epa's guide for industrial waste management: introduction

Guide for

Industrial Waste Management

ProtectingLandGround WaterSurface WaterAir

BuildingPartnerships

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Introduction

In the Guide, you will find:• Considerations for siting industrial waste management units

• Methods for characterizing waste constituents

• Fact sheets and Web sites with information about individual waste constituents

• Tools to assess risks that might be posed by the wastes

• Principles for building stakeholder partnerships

• Opportunities for waste minimization

• Guidelines for safe unit design

• Procedures for monitoring surface water, air, and ground water

• Recommendations for closure and post-closure care

Each year, approximately 7.6 billion tons of industrial solid waste are generated and disposedof at a broad spectrum of American industrial facilities. State, tribal, and some local governmentshave regulatory responsibility for ensuring proper management of these wastes, and their pro-grams vary considerably. In an effort to establish a common set of industrial waste managementguidelines, EPA and state and tribal representatives came together in a partnership and developedthe framework for this voluntary Guide. EPA also convened a focus group of industry and publicinterest stakeholders chartered under the Federal Advisory Committee Act to provide advicethroughout the process. Now complete, we hope the Guide will complement existing regulatoryprograms and provide valuable assistance to anyone interested in industrial waste management.

EPA’s Guide for Industrial Waste ManagementIntroduction

Welcome to EPA’s Guide for Industrial Waste Management. The pur-

pose of the Guide is to provide facility managers, state and tribal

regulators, and the interested public with recommendations and

tools to better address the management of land-disposed, non-haz-

ardous industrial wastes. The Guide can help facility managers make

environmentally responsible decisions while working in partnership

with state and tribal regulators and the public. It can serve as a

handy implementation reference tool for regulators to complement

existing programs and help address any gaps. The Guide can also

help the public become more informed and more knowledgeable in

addressing waste management issues in the community.

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What Are the Underlying Principles of the Guide?When using the Guide for Industrial Waste Management, please keep in mind that it reflects

four underlying principles:

• Protecting human health and the environment. The purpose of the Guide is to pro-mote sound waste management that protects human health and the environment. Ittakes a multi-media approach that emphasizes surface-water, ground-water, and airprotection, and presents a comprehensive framework of technologies and practices thatmake up an effective waste management system.

• Tailoring management practices to risks. There is enormous diversity in the typeand nature of industrial waste and the environmental settings in which it is managed.The Guide provides conservative management recommendations and simple-to-usemodeling tools to tailor management practices to waste- and location-specific risks. Italso identifies in-depth analytic tools to conduct more comprehensive site-specificanalyses.

• Affirming state and tribal leadership. States, tribes, and some local governmentshave primary responsibility for adopting and implementing programs to ensure propermanagement of industrial waste. This Guide can help states, tribes, and local govern-ments in carrying out those programs. Individual states or tribes might have morestringent or extensive regulatory requirements based on local or regional conditions orpolicy considerations. The Guide complements, but does not supersede, those regula-tory programs; it can help you make decisions on meeting applicable regulatoryrequirements and filling potential gaps. Facility managers and the public should con-sult with the appropriate regulatory agency throughout the process to understand regu-latory requirements and how to use this Guide.

• Fostering partnerships. The public, facility managers, state and local governments,and tribes share a common interest in preserving quality neighborhoods, protecting theenvironment and public health, and enhancing the economic well-being of the commu-nity. The Guide can provide a common technical framework to facilitate discussion andhelp stakeholders work together to achieve meaningful environmental results.

What Can I Expect to Find in the Guide?The Guide for Industrial Waste Management is available in both hard-copy and electronic ver-

sions. The hard-copy version consists of five volumes. These include the main volume and foursupporting documents for the ground-water and air fate-and-transport models that were devel-oped by EPA specifically for this Guide. The main volume presents comprehensive informationand recommendations for use in the management of land-disposed, non-hazardous industrialwaste that includes siting the waste management unit, characterizing the wastes that will bedisposed in it, designing and constructing the unit, and safely closing it. The other four vol-umes are the user’s manuals and background documents for the ground-water fate-and-trans-port model—the Industrial Waste Evaluation Model (IWEM)—and the air fate-and-transportmodel—the Industrial Waste Air Model (IWAIR).

Introduction

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The electronic version of the Guide, which can be obtained either on CD-ROM or from EPA’sWeb site <www.epa.gov/epaoswer/non-hw/industd/index.htm>, contains a large collection ofadditional resources. These include an audio-visual tutorial for each main topic of the Guide;the IWEM and IWAIR models developed by EPA for the Guide; other models, including theHELP (Hydrologic Evaluation of Landfill Performance) Model for calculating infiltration rates;and a large collection of reference materials to complement the information provided in each ofthe main chapters, including chemical fact sheets from the Agency for Toxic Substances andDisease Registry, links to Web sites, books on pertinent topics, copies of applicable rules andregulations, and lists of contacts and resources for additional information. The purpose of theaudio-visual tutorials is to familiarize users with the fundamentals of industrial waste manage-ment and potentially expand the audience to include students and international users.

The IWEM and IWAIR models that come with the electronic version of the Guide are criticalto its purpose. These models assess potential risks associated with constituents in wastes andmake recommendations regarding unit design and control of volatile organic compounds tohelp mitigate those risks. To operate, the models must first be downloaded from the Web site orthe CD-ROM to the user’s personal computer.

What Wastes Does the Guide Address?The Guide for Industrial Waste Management addresses non-hazardous industrial waste subject

to Subtitle D of the Resource Conservation and Recovery Act (RCRA). The reader is referred tothe existence of 40 CFR Part 257, Subparts A and B, which provide federal requirements fornon-hazardous industrial waste facilities or practices. Under RCRA, a waste is defined as non-hazardous if it does not meet the definition of hazardous waste and is not subject to RCRASubtitle C regulations. Defining a waste as non-hazardous under RCRA does not mean that themanagement of this waste is without risk.

This Guide is primarily intended for new industrial waste management facilities and units,such as new landfills, new waste piles, new surface impoundments, and new land applicationunits. Chapter 7B–Designing and Installing Liners, and Chapter 4–Considering the Site, areclearly directed toward new units. Other chapters, such as Chapter 8–Operating the WasteManagement System, Chapter 9–Monitoring Performance, Chapter 10–Taking CorrectiveAction, Chapter 11–Performing Closure and Post-Closure Care, while primarily intended fornew units, can provide helpful information for existing units as well.

What Wastes Does the Guide Not Address?The Guide for Industrial Waste Management is not intended to address facilities that primarily

handle the following types of waste: household or municipal solid wastes, which are managedin facilities regulated by 40 CFR Part 258; hazardous wastes, which are regulated by Subtitle Cof RCRA; mining and some mineral processing wastes; and oil and gas production wastes;mixed wastes, which are solid wastes mixed with radioactive wastes; construction and demoli-tion debris; and non-hazardous wastes that are injected into the ground by the use of shallowunderground injection wells (these injection wells fall under the Underground Injection Control(UIC) Program).

Introduction

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Furthermore, while the Guide provides many tools for assessing appropriate industrial wastemanagement, the information provided is not intended for use as a replacement for other exist-ing EPA programs. For example, Tier 1 ground-water risk criteria can be a useful conservativescreening tool for certain industrial wastes that are to be disposed in new landfills, surfaceimpoundments, waste piles, or land application units, as intended by the Guide. Theseground-water risk criteria, however, cannot be used as a replacement for sewage sludge stan-dards, hazardous waste identification exit criteria, hazardous waste treatment standards, MCLdrinking water standards, or toxicity characteristics to identify when a waste is hazardous—allof which are legally binding and enforceable. In a similar manner, the air quality tool in thisGuide does not and cannot replace Clean Air Act Title V permit conditions that may apply toindustrial waste disposal units. The purpose of this Guide is to help industry, state, tribal, andenvironmental representatives by providing a wealth of information that relays and defers toexisting legal requirements.

What is the Relationship Between This Guide and Statutory orRegulatory Provisions?

Please recognize that this is a voluntary guidance document, not a regulation, nor does itchange or substitute for any statutory or regulatory provisions. This document presents techni-cal information and recommendations based on EPA’s current understanding of a range ofissues and circumstances involved in waste management The statutory provisions and EPA reg-ulations contain legally binding requirements, and to the extent any statute or regulatory provi-sion is cited in the Guide, it is that provision, not the Guide, which is legally binding andenforceable. Thus, this Guide does not impose legally binding requirements, nor does it conferlegal rights or impose legal obligations on anyone or implement any statutory or regulatoryprovisions. When a reference is made to a RCRA criteria, for example, EPA does not intend toconvey that any recommended actions, procedures, or steps discussed in connection with thereference are required to be taken. Those using this Guide are free to use and accept othertechnically sound approaches. The Guide contains information and recommendations designedto be useful and helpful to the public, the regulated community, states, tribes, and local gov-ernments. The word “should” as used in the Guide is intended solely to recommend particularaction and does not connote a requirements. Similarly, examples are presented as recommenda-tions or demonstrations, not as requirements. To the extent any products, trade name, or com-pany appears in the Guide, their mention does not constitute or imply endorsement orrecommendation for use by either the U.S. Government or EPA. Interested parties are free toraise questions and objections about the appropriateness of the application of the examplespresented in the Guide to a particular situation.

Introduction

Part IGetting Started

Chapter 1Understanding Risk and Building Partnerships

Contents

I. Understanding Risk Assessment ................................................................................................................1 - 1

A. Introduction to Risk Assessment ..........................................................................................................1 - 1

B. Types of Risk..........................................................................................................................................1 - 2

C. Assessing Risk........................................................................................................................................1 - 3

1. Hazard Identification ........................................................................................................................1 - 5

2. Exposure Assessment: Pathways, Routes, and Estimation ..................................................................1 - 5

3. Risk Characterization ........................................................................................................................1 - 8

4. Tiers for Assessing Risk....................................................................................................................1 - 10

D. Results ................................................................................................................................................1 - 10

II. Information on Environmental Releases................................................................................................1 - 11

III. Building Partnerships............................................................................................................................1 - 11

A. Develop a Partnership Plan ..................................................................................................................1 - 12

B. Inform the State and Public About New Facilities or Significant Changes in Facility Operating Plans ....................................................................................................1 - 13

C. Make Knowledgeable and Responsible People Available for Sharing Information ................................1 - 16

D. Provide Information About Facility Operations....................................................................................1 - 16

Understanding Risk and Building Partnerships Activity List........................................................................1 - 19

Resources ....................................................................................................................................................1 - 20

Appendix ....................................................................................................................................................1 - 22

Tables:

Table 1: Effective Methods for Public Notification ....................................................................................1- 14

Figures:

Figure 1: Multiple Exposure Pathways/Routes............................................................................................1 - 7

Getting Started—Understanding Risk and Building Partnerships

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Residents located near waste man-agement units want to understandthe management activities takingplace in their neighborhoods. Theywant to know that waste is being

managed safely, without danger to publichealth or the environment. This requires anunderstanding of the basic principles of riskassessment and the science behind it.Opportunities for dialogue between facilities,states, tribes, and concerned citizens, includ-ing a discussion of risk factors, should takeplace before decisions are made. Remember,successful partnerships are an ongoing activity.

I. UnderstandingRisk Assessment

Environmental risk communication skillsare critical to successful partnerships betweencompanies, state regulators, the public, andother stakeholders. As more environmentalmanagement decisions are made on the basisof risk, it is increasingly important for all inter-ested parties to understand the science behindrisk assessment. Encouraging public participa-tion in environmental decision-making meansensuring that all interested parties understandthe basic principles of risk assessment and canconverse equally on the development ofassumptions that underlie the analysis.

A. Introduction to RiskAssessment

This Guide provides simple-to-use riskassessment tools that can assist in determiningthe appropriate waste management practicesfor surface impoundments, landfills, wastepiles, and land application units. The toolsestimate potential human health impacts froma waste management unit by modeling twopossible exposure pathways: releases throughvolatile air emissions and contaminant migra-tion into ground water. Although using thetools is simple, it is still essential to under-stand the basic concepts of risk assessment tobe able to interpret the results and understandthe nature of any uncertainties associated withthe analysis. This section provides a generaloverview of the scientific principles underly-ing the methods for quantifying cancer and

Understanding Risk and Building PartnershipsThis chapter will help you:

• Understand the basic principles of risk assessment and the science

behind it.

• Build partnerships between a company that generates and man-

ages waste, the community within which the company lives and

works, and the state agency that regulates the company in order

to build trust and credibility among all parties.

This chapter will help address the fol-lowing questions.

• What is risk and how is it assessed?

• What are the benefits of buildingpartnerships?

• What methods have been successfulin building partnerships?

• What is involved in preparing astakeholder meeting?

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noncancer risk. Ultimately, understanding thescientific principles will lead to more effectiveuse of the provided tools.

B. Types of RiskRisk is a concept used to describe situa-

tions or circumstances that pose a hazard topeople or things they value. People encountera myriad of risks during common everydayactivities, such as driving a car, investingmoney, and undergoing certain medical pro-cedures. By definition, risk is comprised oftwo components: the probability that anadverse event will occur and the magnitudeof the consequences of that adverse event. Incapturing these two components, risk is typi-cally stated in terms of the probability (e.g.,one chance in one million) of a specificharmful “endpoint” (e.g., accident, fatality,cancer).

In the context of environmental manage-ment and this section in the Guide, risk isdefined as the probability or likelihood thatpublic health might be unacceptably impact-ed from exposure to chemicals contained inwaste management units. The risk endpointsresulting from the exposure are typicallygrouped into two major consequence cate-gories: cancer risk and noncancer risk.

The cancer risk category captures risksassociated with exposure to chemicals thatmight initiate cancer. To determine a cancerrisk, one must calculate the probability of anindividual developing any type of cancer dur-ing his or her lifetime from exposure to car-cinogenic hazards. Cancer risk is generallyexpressed in scientific notation; in this nota-tion, the chance of 1 person in 1,000,000 ofdeveloping cancer would be expressed as 1 x10-6 or 1E-6.

The noncancer risk category is essentially acatch-all category for the remaining healtheffects resulting from chemical exposure.

Noncancer risk encompasses a diverse set ofeffects or endpoints, such as weight loss,enzyme changes, reproductive and develop-mental abnormalities, and respiratory reac-tions. Noncancer risk is generally assessed bycomparing the exposure or average intake of achemical with a corresponding reference (ahealth benchmark), thereby creating a ratio.The ratio so generated is referred to as thehazard quotient (HQ). An HQ that is greaterthan 1 indicates that the exposure level isabove the protective level of the health bench-mark, whereas, an HQ less than 1 indicatesthat the exposure is below the protective levelestablished by the health benchmark.

It is important to understand that exposureto a chemical does not necessarily result in anadverse health effect. A chemical’s ability toinitiate a harmful health effect depends onthe toxicity of the chemical as well as theroute (e.g., ingestion, inhalation) and dose(the amount that a human intakes) of theexposure. Health benchmark values are usedto quantify a chemical’s possible toxicity andability to induce a health effect, and arederived from toxicity data. They represent a“dose-response”1 estimate that relates the like-lihood and severity of adverse health effectsto exposure and dose. The health benchmarkis used in combination with an individual’sexposure level to determine if there is a risk.Because individual chemicals generate differ-ent health effects at different doses, bench-marks are chemical specific; additionally,since health effects are related to the route ofexposure and the timing of the exposure,health benchmarks are specific to the routeand the duration (acute, subchronic, orchronic) of the exposure. The definitions ofacute, subchronic, and chronic exposuresvary, but acute typically implies an exposureof less than one day, subchronic generallyindicates an exposure of a few weeks to a fewmonths, and chronic exposure can span peri-ods of several months to several years.

1 Dose-response is the correlative relationship between the dose of a chemical received by a subject and thedegree of response to that exposure.


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The health benchmark for carcinogens iscalled the cancer slope factor. A cancer slopefactor (CSF) is defined as the upper-bound2

estimate of the probability of a response perunit intake of a chemical over a lifetime and isexpressed in units of (mg/kg-d). The slope fac-tor is used to estimate an upper-bound proba-bility of an individual developing cancer as aresult of a lifetime of exposure to a particularconcentration of a carcinogen.

A reference dose (RfD) for oral exposureand reference concentration (RfC) for inhala-tion exposure are used to evaluate noncancereffects. The RfD and RfC are estimates of dailyexposure levels to individuals (including sen-sitive populations) that are likely to be with-out an appreciable risk of deleterious effectsduring a lifetime and are expressed in units ofmg/kg-d (RfD) or mg/m3 (RfC).

Most health benchmarks reflect somedegree of uncertainty because of the lack ofprecise toxicological information on the peo-ple who might be most sensitive (e.g., infants,elderly, nutritionally or immunologically com-promised) to the effects of hazardous sub-stances. There is additional uncertaintybecause most benchmarks must be based onstudies performed on animals, as relevanthuman studies are lacking. From time-to-timebenchmark values are revised to reflect newtoxicology data on a chemical. In addition,because many states have developed their owntoxicology benchmarks, both the ground-water and air tools in this Guide enable a userto input alternative benchmarks to those thatare provided.

There are several sources for obtaininghealth benchmarks, some of which are sum-marized in the text box on the following page.Most of these sources have toxicological pro-files and fact sheets on specific chemicals thatare written in a general manner and summa-rize the potential risks of a chemical and howit is currently regulated. One good Internet

source is the Agency for Toxic Substances andDisease Registry (ATSDR) <www.atsdr.cdc.gov>. ATSDR provides fact sheets for manychemicals. These fact sheets are easy to under-stand and provide general information regard-ing the chemical in question. An example forcadmium is provided in the appendix at theend of this chapter. Additional Internet sitesare also available such as: the Integrated RiskInformation System (IRIS); EPA’s Office of AirQuality Planning and Standards Hazardous AirPollutants Fact Sheets; EPA’s Office of GroundWater and Drinking Water Contaminant FactSheets; New Jersey’s Department of Health,Right to Know Program’s Hazardous SubstanceFact Sheets; Environmental Defense’sChemical Scorecard; EPA’s Office of PollutionPrevention and Toxics (OPPT) Chemical FactSheets, American Chemistry Council (ACC),and several others. Visit the EnvirofactsWarehouse Chemical References CompleteIndex at <www.epa.gov/enviro/html/emci/chemref/complete_index.html> for links tothese Web sites.

C. Assessing RiskSound risk assessment involves the use of

an organized process of evaluating scientificdata. A risk assessment ultimately serves as

2 Upper-bound is a number that is greater than or equal to any number in a set.

Example of Health Benchmarks forAcrylonitrile

Chronic:inhalation CSF: 0.24 (mg/kg-d)oral CSF: 0.54 (mg/kg-d)RfC: 0.002 mg/m3

RfD: 0.001 mg/kg-d

Subchronic:RfC: 0.02 mg/m3

Acute:ATSDR MRL: 0.22 mg/m3

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guidance for making management decisions byproviding one of the inputs to the decisionmaking process. Risk assessment furnishes ben-eficial information for a variety of situations,such as determining the appropriate pollutioncontrol systems for an industrial site, predictingthe appropriateness of different waste manage-ment options or alternative waste managementunit configurations, or identifying exposuresthat might require additional attention.

The risk assessment process involves datacollection activities, such as identifying andcharacterizing the source of the environmentalpollutant, determining the transport of the pol-lutant once it is released into the environment,determining the pathways of human exposure,

and identifying the extent of exposure for indi-viduals or populations at risk.

Performing a risk assessment is complex andrequires knowledge in a number of scientificdisciplines. Experts in several areas, such astoxicology, geochemistry, environmental engi-neering, and meteorology, can be involved inperforming a risk assessment. For the purposeof this section, and for brevity, the basic com-ponents important to consider when assessingrisk are summarized in three main categorieslisted below. A more extensive discussion ofthese components can be found in the refer-ences listed at the end of this section. Thethree main categories are:

Sources for Health BenchmarksIntegrated Risk Information System (IRIS) The

Integrated Risk Information System (IRIS) is theAgency's official repository of Agency-wide, consensus,chronic human health risk information. IRIS containsAgency consensus scientific positions on potentialadverse human health effects that might result fromchronic (or lifetime) exposure to environmental contam-inants. IRIS information includes the reference dose fornoncancer health effects resulting from oral exposure,the reference concentration for noncancer health effectsresulting from inhalation exposure, and the carcinogenassessment for both oral and inhalation exposure. IRIScan be accessed at <www.epa.gov/iris>.

Health Effects Assessment Summary Tables(HEAST) HEAST is a comprehensive listing compiledby EPA consisting of risk assessment information relativeto oral and inhalation routes for chemicals. HEASTbenchmarks are considered secondary to those con-tained in IRIS. Although the entries in HEAST haveundergone review and have the concurrence of individ-ual Agency Program Offices, they have either not beenreviewed as extensively as those in IRIS or they do nothave as complete a data set as is required for a chemicalto be listed in IRIS. HEAST can be ordered from NTIS

by calling 1-800-553-IRIS or accessing their Website at<www.ntis.gov>.

Agency for Toxic Substances and Disease Registry(ATSDR) The Comprehensive Environmental Response,Compensation, and Liability Act (CERCLA), requiresthat the Agency for Toxic Substances and DiseaseRegistry (ATSDR) develop jointly with the EPA, in orderof priority, a list of hazardous substances most common-ly found at facilities on the CERCLA National PrioritiesList; prepare toxicological profiles for each substanceincluded on the priority list of hazardous substances;ascertain significant human exposure levels (SHELs) forhazardous substances in the environment, and the asso-ciated acute, subchronic, and chronic health effects; andassure the initiation of a research program to fill identi-fied data needs associated with the substances. TheATSDR Minimal Risk Levels (MRLs) were developed asan initial response to the mandate. MRLs are based onnoncancer health effects only and are not based on aconsideration of cancer effects. MRLs are derived foracute (1-14 days), intermediate (15-364 days), andchronic (365 days and longer) exposure durations, forthe oral and inhalation routes of exposure. ATSDR's tox-icological profiles can be accessed at <www.atsdr.cdc.gov/toxfaq.html>.


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1. Hazard Identification: identifyingand characterizing the source of thepotential risk (e.g., chemicals man-aged in a waste management unit).

2. Exposure Assessment: determiningthe exposure pathways and exposureroutes from the source to an individual.

3. Risk Characterization: integratingthe results of the exposure assess-ment with information on who ispotentially at risk (e.g., location ofthe person, body weights) and chem-ical toxicity information.

1. Hazard IdentificationFor the purpose of the Guide, the source

of the potential risk has already been identi-fied: waste management units. However,there must be a release of chemicals from awaste management unit for there to be expo-sure and risk. Chemicals can be released fromwaste management units by a variety ofprocesses, including volatilization (wherechemicals in vapor phase are released to theair), leaching to ground water (where chemi-cals travel through the ground to a ground-water aquifer), particulate emission (wherechemicals attached to particulate matter arereleased in the air when the particulate mat-ter becomes airborne), and runoff and ero-sion (where chemicals in soil water orattached to soil particles move to the sur-rounding area).

To consider these releases in a risk assess-ment, information characterizing the wastemanagement unit is needed. Critical parame-ters include the size of the unit and its loca-tion. For example, larger units have thepotential to produce larger releases. Unitslocated close to the water table might pro-duce greater releases to ground water thanunits located further from the water table.Units located in a hot, dry, windy climate can

produce greater volatile releases than units ina cool, wet, non-windy climate.

2. Exposure Assessment:Pathways, Routes, andEstimation

Individuals and populations can come intocontact with environmental pollutants by avariety of exposure mechanisms and process-es. The mere presence of a hazard, such astoxic chemicals in a waste management unit,does not denote the existence of a risk.Exposure is the bridge between what is con-sidered a hazard and what actually presents arisk. Assessing exposure involves evaluatingthe potential or actual pathways for andextent of human contact with toxic chemi-cals. The magnitude, frequency, duration, androute of exposure to a substance must beconsidered when collecting all of the datanecessary to construct a complete exposureassessment.

The steps for performing an exposureassessment include identifying the potentiallyexposed population (receptors); pathways ofexposure; environmental media that transportthe contaminant; contaminant concentrationat a receptor point; and receptor’s exposuretime, frequency, and duration. In a determin-istic exposure assessment, single values areassigned to each exposure variable. For exam-ple, the length of time a person lives in thesame residence adjacent to the facility mightbe assumed to be 30 years. Alternatively, in aprobabilistic analysis, single values can bereplaced with probability distribution func-tions that represent the range in real-worldvariability, as well as uncertainty. Using thetime in residence example, it might be foundthat 10 percent of the people adjacent to thefacility live in their home for less than threeyears, 50 percent less than six years, 90 per-cent less than 20 years, and 99 percent lessthan 27 years.

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A probabilistic risk assessment is per-formed by running the equations thatdescribe each distribution in a program inconjunction with a Monte Carlo program.The Monte Carlo program randomly selects avalue from the designated distribution andmathematically treats it with numbers ran-domly selected from distributions for otherparameters. This process is repeated a num-ber of times (e.g., 10,000 times) to generate adistribution of theoretical values. The personassessing risk then uses his or her judgementto select the risk value (e.g., 50th or 90thpercentile).

The output of the exposure assessment is anumerical estimate of exposure and intake ofa chemical by an individual. The intake infor-mation is then used in concert with chemical-specific health benchmarks to quantify risksto human health.

Before gathering these data, it is importantto understand what information is necessaryfor conducting an adequate exposure assess-ment and what type of work might berequired. Exposures are commonly deter-mined by using mathematical models ofchemical fate and transport to determinechemical movement in the environment inconjunction with models of human activitypatterns. The information required for per-forming the exposure assessment includessite-specific data such as soil type, meteoro-logical conditions, ground-water pH, andlocation of the nearest receptor. Informationmust be gathered for the two components ofexposure assessment: exposurepathways/routes and exposure quantifica-tion/estimation.

a. Exposure Pathways/Routes

An exposure pathway is the course thechemical takes from its source to the individ-ual or population it reaches. Chemicals cyclein the environment by crossing through the

different types of media which are consideredexposure pathways: air, soil, ground water,surface water, and biota (Figure 1). As a resultof this movement, a chemical can be presentin various environmental media, and humanexposure often results from multiple sources.The relative importance of an exposure path-way depends on the concentration of a chemi-cal in the relevant medium and the rate ofintake by the exposed individual. In a com-prehensive risk assessment, the risk assessoridentifies all possible site-specific pathwaysthrough which a chemical could move andreach a receptor. The Guide provides tools tomodel the transport and movement of chemi-cals through two environmental pathways: airand ground water.

The transport of a chemical in the environ-ment is facilitated by natural forces: wind andwater are the primary physical processes fordistributing contaminants. For example,atmospheric transport is frequently caused byambient wind. The direction and speed of thewind determine where a chemical can befound. Similarly, chemicals found in surfacewater and ground water are carried by watercurrents or sediments suspended in the water.

The chemistry of the contaminants and ofthe surrounding environment, often referredto as the “system,” also plays a significant rolein determining the ultimate distribution ofpollutants in the various types of media.Physical-chemical processes, including disso-lution/precipitation, volatilization, photolyticand hydrolytic degradation, sorption, andcomplexation, can influence the distributionof chemicals among the different environ-mental media and the transformation fromone chemical form to another3. An importantcomponent of creating a conceptual modelfor performing a risk assessment is the identi-fication of the relevant processes that occur ina system. These complex processes dependon the conditions at the site and specificchemical properties.

3 Kolluru, Rao (1996).


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Whereas the exposure pathway dictates themeans by which a contaminant can reach anindividual, the exposure route is the way inwhich that chemical comes in contact withthe body. To generate a health effect, thechemical must come in contact with the body.In environmental risk assessment, three expo-sure routes are generally considered: inges-tion, inhalation, and dermal absorption. Asstated earlier, the toxicity of a chemical is spe-cific to the dose received and its means ofentry into the body. For example, a chemicalthat is inhaled might prove to be toxic andresult in a harmful health effect, whereas thesame chemical might cause no reaction ifingested, or vice-versa. This phenomenon isdue to the differences in physiologicalresponse once a chemical enters the body. Achemical that is inhaled reaches the lungs andenters the blood system. A chemical that isingested might be metabolized into a differentchemical that might result in a health effect or

into another chemical that is solu-ble and can be excreted.

Some contaminants can also beabsorbed by the skin. The skin isnot very permeable and usuallyprovides a sufficient barrier againstmost chemicals. Some chemicals,however, can pass through theskin in sufficient quantities toinduce severe health effects. Anexample is carbon tetrachloride,which is readily absorbed throughthe skin and at certain doses cancause severe liver damage. Thedermal route is typically consid-ered in worker scenarios in whichthe worker is actually performingactivities that involve skin contactwith the chemical of concern. Thetools provided in the Guide do not address the dermal route ofexposure.

b. Exposure Quantification/Estimation

Once appropriate fate-and-transport mod-eling has been performed for each pathway,providing an estimate of the concentration ofa chemical at an exposure point, the chemicalintake by a receptor must be quantified.Quantifying the frequency, magnitude, andduration of exposures that result from thetransport of a chemical to an exposure pointis critical to the overall assessment. For thisstep, the risk assessor calculates the chemical-specific exposures for each exposure pathwayidentified. Exposure estimates are expressedin terms of the mass of a substance in contactwith the body per unit body weight per unittime (e.g., milligrams of a chemical per kilo-gram body weight per day, also expressed asmg/kg-day).

The exposure quantification processinvolves gathering information in two mainareas: the activity patterns and the biological

Figure 1. Multiple Exposure Pathways/Routes (National ResearchCouncil, “Frontiers in Assesssing Human Exposure,” 1991)

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characteristics (e.g., body weight, inhalationrate) of receptors. Activity patterns and bio-logical characteristics dictate the amount of aconstituent that a receptor can intake and thedose that is received per kilogram of bodyweight. Chemical intake values are calculatedusing equations that include variables forexposure concentration, contact rate, exposurefrequency, exposure duration, body weight,and exposure averaging time. The values ofsome of these variables depend on the siteconditions and the characteristics of thepotentially exposed population. For example,the rate of oral ingestion of contaminated foodis different for different subgroups of recep-tors, which might include adults, children,area visitors, subsistence farmers, and subsis-tence fishers. Children typically drink greaterquantities of milk each day than adults perunit body weight. A subsistence fisher wouldbe at a greater risk than another area residentfrom the ingestion of contaminated fish.Additionally, a child might have a greater rateof soil ingestion than an adult due to playingoutdoors or hand-to-mouth behavior patterns.The activities of individuals also determine theduration of exposure. A resident might live inthe area for 20 years and be in the area formore than 350 days each year. Conversely, avisitor or a worker will have shorter exposuretimes. After the intake values have been esti-mated, they should be organized by popula-tion as appropriate (e.g., children, adultresidents) so that the results in the risk char-acterization can be reported for each popula-tion group. To the extent feasible, site-specificvalues should be used for estimating the expo-sures; otherwise, default values suggested bythe EPA in The Exposure Factors Handbook(EPA, 1995) can be used.

3. Risk CharacterizationIn the risk-characterization process, the

health benchmark information (i.e., cancerslope factors, reference doses, reference concen-

Key Chemical ProcessesSorption: the partitioning of a chemical between the liq-

uid and solid phase determined by its affinity for adheringto other solids in the system such as soils and sediment.The amount of chemical that “sorbs” to solids and does notmove through the environment is dependent upon thecharacteristics of the chemical, the characteristics of thesurrounding soils and sediments, and the quantity of thechemical. A sorption coefficient is the measure of a chemi-cal’s ability to sorb. If too much of the chemical is present,the available binding sites on soils and sediments will befilled and sorption will not continue.

Dissolution/precipitation: the taking in or coming out ofsolution by a substance. In dissolution a chemical is takeninto solution; precipitation is the formation of an insolublesolid. These processes are a function of the nature of thechemical and its surrounding environment and are depen-dent on properties such as temperature and pH. A chemical’ssolubility is characterized by a solubility product. Chemicalsthat tend to volatilize rapidly are not highly soluble.

Degradation: the break down of a chemical into othersubstances in the environment. Some degradation processesinclude biodegradation, hydrolysis, and photolysis. Not alldegradation products have the same risk as the “parent”compound. Although most degradation products presentless risk than the parent compound, some chemicals canbreak down into “daughter” products that are more harmfulthan the parent compound. In performing a risk assessmentit is important to consider what the daughter products ofdegradation might be.

Bioaccumulation: the take up/ingestion and storage of asubstance into an organism. For substances that bioaccu-mulate, the concentrations of the substance in the organismcan exceed the concentrations in the environment since theorganism will store the substance and not excrete it.

Volatilization: the partitioning of a compound into agaseous state. The volatility of a compound is dependenton its water solubility and vapor pressure. The extent towhich a chemical can partition into air is described by oneof two constants: Henry's Law or Rauolt's Law. Other fac-tors that are important to volatility are atmospheric temper-ature and waste mixing.


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trations) and the results of the exposure assess-ment (estimated intake or dose by potentiallyexposed populations) are integrated to arrive atquantitative estimates of cancer and noncancerrisks. To characterize the potential noncarcino-genic effects, comparisons are made betweenprojected intake levels of substances and refer-ence dose or reference concentration values. Tocharacterize potential carcinogenic effects,probabilities that an individual will developcancer over a lifetime are estimated from pro-jected intake levels and the chemical-specificcancer slope factor value. This procedure is thefinal calculation step. This step determines whois likely to be affected and what the likelyeffects are. Because of all the assumptionsinherent in calculating a risk, a risk characteri-zation cannot be considered complete unlessthe numerical expressions of risk are accompa-nied by explanatory text interpreting and quali-fying the results. As shown in the text box, therisk characterization step is different for car-cinogens and noncarcinogens.

Another consideration during the risk-characterization phase is the cumulativeeffects of multiple exposures. A given popula-tion can be exposed to multiple chemicalsfrom several exposure routes and sources.Multiple constituents might be managed in asingle waste management unit, for example,and by considering one chemical at a time,the risks associated with the waste manage-

ment unit might be underestimated. The EPAhas developed guidance outlined in the RiskAssessment Guidance for Superfund, Volume I(U.S. EPA, 1989b) to assess the overall poten-tial for cancer and noncancer effects posed bymultiple chemicals. The risk assessor, facilitymanager, and other interested parties shoulddetermine the appropriateness of adding therisk contribution of each chemical for eachpathway to calculate a cumulative cancer riskor noncancer risk. The procedures for addingrisks differ for carcinogenic and noncarcino-genic effects.

The cancer-risk equation described in theadjacent box estimates the incremental indi-vidual lifetime cancer risk for simultaneousexposure to several carcinogens and is basedon EPA (1989a) guidance. The equation com-bines risks by summing the risks to a recep-tor from each of the carcinogenic chemicals.

Assessing cumulative effects from noncar-cinogens is more difficult and contains agreater amount of uncertainty than an assess-ment for carcinogens. As discussed earlier,noncarcinogenic risk covers a diverse set ofhealth effects and different chemicals willhave different effects. To assess the overallpotential for noncarcinogenic effects posed bymore than one chemical, EPA developed ahazard index (HI) approach. The approachassumes that the magnitude of an adverse

Calculating RiskCancer Risks:

Incremental risk of cancer = averagedaily dose (mg/kg-day) * slope factor(mg/kg-day)

Non-Cancer Risks:Hazard quotient = exposure or intake

(mg/kg-day) or (mg/m3)/ RfD (mg/kg-day) or RfC (mg/m3)

Cancer Risk Equation forMultiple Substances

RiskT = �Riski

where:

RiskT = the total cancer risk,expressed as a unitless probability.

�Riski = the sum of the risk estimatesfor all of the chemical risks.

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health effect is proportional to the sum of thehazard quotients of each of the chemicalsinvestigated. In keeping with EPA’s RiskAssessment Guidance, hazard quotients shouldonly be added for chemicals that have thesame critical effect (e.g., both chemicals affectthe liver or both initiate respiratory distress).As a result, an extensive knowledge of toxi-cology is needed to sum the hazard quotientsto produce a hazard index. Segregation ofhazard indices by effect and mechanism ofaction can be complex, time-consuming, andwill have some degree of uncertainty associat-ed with it. This analysis is not simple andshould be performed by a toxicologist.

4. Tiers for Assessing RiskAs part of the Guide, EPA has used a 3-

tiered approach for assessing risk associatedwith air and water releases from waste man-agement units. Under this approach, anacceptable level of protection is providedacross all tiers, but with each progressive tierthe level of uncertainty in the risk analysis isreduced. Reducing the level of uncertainty inthe risk analysis might reduce the level ofcontrol required by a waste management unit(if appropriate for the site), while maintainingan acceptable level of protection. The facilityperforming the risk assessment accepts thehigher costs associated with a more complexrisk assessment in return for greater certaintyand potentially reduced construction andoperating costs.

The advantages and relative costs of eachtier are outlined below.

Tier 1 Evaluation

• Allows for a rapid but conservativeassessment.

• Lower cost.

• Requires minimal site data.

• Contaminant fate-and-transport andexposure assumptions are developed

using conservative, non-site specificassumptions provided by EPA. Thevalues are provided in “look-uptables” that serve as a quick andstraightforward means for assessingrisk. These values are calculated to beprotective over a broad range of con-ditions and situations and are bydesign very conservative.

Tier 2 Evaluation

• Represents a higher level of complex-ity.

• Moderate cost.

• Provides the ability to input somesite-specific data into the risk assess-ment and thus provides a more accu-rate representation of site risk.

• Uses relatively simplistic fate andtransport models.

Tier 3 Evaluation

• Provides a sophisticated risk assess-ment.

• Higher cost.

• Provides the maximum use of site-specific data and thus provides themost accurate representation of siterisk.

• Uses more complex fate-and-trans-port models and analyses.

D. ResultsThe results of a risk assessment provide a

basis for making decisions but are only oneelement of input into the process of designinga waste management unit. The risk assess-ment does not constitute the only basis formanagement action. Other factors are alsoimportant, such as technical feasibility ofoptions, public values, and economics.Understanding and interpreting the resultsfor the purpose of making decisions alsorequires a thorough knowledge of the

assumptions that were applied during therisk assessment. Ample documentationshould be assembled to describe the scenariosthat were evaluated for the risk assessmentand any uncertainty associated with the esti-mate. Information that should be consideredfor inclusion in the risk assessment documen-tation include: a description of the contami-nants that were evaluated; a description ofthe risks that are present (i.e., cancer, non-cancer); the level of confidence in the infor-mation used in the assessment; the majorfactors driving the site risks; and the charac-teristics of the exposed population. Theresults of a risk assessment are essentiallymeaningless without the information on howthey were generated.

II. Information onEnvironmentalReleases

There are several available sources of infor-mation that citizens can review to understandchemical risk better and to review potentialenvironmental release from waste manage-ment units in their communities. TheEmergency Planning and Community Right-to-Know Act (EPCRA) of 1986 provides onesuch resource. EPCRA created the ToxicRelease Inventory (TRI) reporting programwhich requires facilities in designatedStandard Industry Codes (see 40 CFR§372.22) with more than 10 employees thatmanufacture or process more than 25,000pounds, or otherwise use more than 10,000pounds, of a TRI- listed chemical to reporttheir environmental releases annually to EPAand state governments. Environmental releas-es include the disposal of wastes in landfills,surface impoundments, land applicationunits, and waste piles. EPA compiles thesedata in the TRI database and release thisinformation to the public annually. Facility

operators might wish to include TRI data inthe facility’s information repository. TRI data,however, are merely raw data. When estimat-ing risk, other considerations need to beexamined and understood too, such as thenature and characteristics of the specific facil-ity and surrounding community.

In 1999, EPA promulgated a final rule thatestablished alternate thresholds for severalpersistent, bioaccumulative, and toxic (PBT)chemicals (see 64 FR 58665; October 29,1999). In this rule, EPA has added sevenchemicals to the EPCRA Section 313 list ofTRI chemicals and lowered the reportingthresholds for another 18 PBT chemicals andchemical categories. For these 18 chemicals,the alternate thresholds are significantly lowerthan the standard reporting thresholds of25,000 pounds manufactured or processed,and 10,000 pounds otherwise used.

EPCRA is based on the belief that citizenshave a right to know about potential environ-mental risks caused by facility operations intheir communities, including those posed as aresult of waste management. TRI data, there-fore, provide yet another way for residents tolearn about the waste management activitiestaking place in their neighborhood and totake a more active role in decisions thatpotentially affect their health and environ-ment. More information on TRI and access toTRI data can be obtained from EPA’s Web site<www.epa.gov/tri>.

III. BuildingPartnerships

Building partnerships between all stake-holders—the community, the facility, and theregulators—can provide benefits to all par-ties, such as:


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• Better understanding of waste man-agement activities at an industrialfacility.

• Better understanding of facility, state,and community issues.

• Greater support of industry proce-dures and state policies.

• Reduced delays and costs associatedwith opposition and litigation.

• A positive image for a company andrelationship with the state and com-munity.

Regardless of the size or type of a facility’swaste management unit, facilities, states, andlocal communities can all follow similar prin-ciples in the process of building partnerships.These principles are described in variousstate public involvement guidance docu-ments, various EPA publications, and staterequirements for waste facilities. These prin-ciples embody sound business practices andcommon sense and can go beyond staterequirements that call for public participationduring the issuance of a permit. The Guiderecommends principles that can be adoptedthroughout the operating life of a facility, notjust during the permitting process. Followingthese principles will help all involved consid-er the full range of activities possible to givepartners an active voice in the decision-mak-ing process, and in so doing, will result in apositive working relationship.

A. Develop a PartnershipPlan

The key to effective involvement is goodplanning. Developing a plan for how andwhen to involve all parties in making deci-sions will help make partnership activities runsmoothly and achieve the best results.Developing a partnership plan also helps iden-tify concerns and determine which involve-

ment activities bestaddress those con-cerns.

The first step indeveloping a part-nership plan is towork with the stateagency to under-stand what involve-ment requirementsexist. Existing staterequirements deal-ing with partnership plans must be followed.(Internet sites for all state environmentalagencies are available from <www.astswmo.org/links.htm>.) After this step, you shouldassess the level of community interest gener-ated by a facility’s waste management activi-ties. Several criteria influence the amount ofpublic interest, including implications forpublic health and welfare, current relation-ships between the facility and communitymembers, and the community’s political andeconomic climate. Even if a facility has notgenerated much public interest in the past,involving the public is a good idea. Interestin a facility can increase suddenly whenchanges to existing activities are proposed orwhen residents’ attitudes and a community’spolitical or economic climate change.

To gauge public interest in a facility’s wastemanagement activities and to identify thecommunity’s major concerns, facility repre-sentatives should conduct interviews withcommunity members. They can first talkwith members of community groups, such ascivic leagues, religious organizations, andbusiness associations. If interest in the facili-ty’s waste management activities seems high,facility representatives can consider conduct-ing a more comprehensive set of communityinterviews. Other individuals to interviewinclude the facility’s immediate neighbors,representatives from other agencies and envi-

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ronmental organizations, and any individualsin the community who have expressed inter-est in the facility’s operations.

Using the information gathered during theinterviews, facility representatives can devel-op a list of the community’s concerns regard-ing the facility’s waste management activities.They can then begin to engage the communi-ty in discussions about how to address thoseconcerns. These discussions can form thebasis of a partnership plan.

B. Inform the State andPublic About NewFacilities or SignificantChanges in FacilityOperating Plans

A facility’s decision to change its opera-tions provides a valuable opportunity forinvolvement. Notifying the state and publicof new units and proposed changes at exist-ing facilities gives these groups the opportu-nity to identify applicable state requirementsand comment on matters that apply to them.

What are examples of effective

methods for notifying the public?

Table 1 presents examples of effectivemethods for public notification and associat-ed advantages and disadvantages. Themethod used at a particular facility, andwithin a particular community, will dependon the type of information or issues thatneed to be communicated and addressed.Public notices usually provide the name andaddress of the facility representative and abrief description of the change being consid-ered. After a public notice is issued, a facilitycan develop informative fact sheets toexplain proposed changes in more detail.Fact sheets and public notices can includethe name and telephone number of a contact

person who is available within the facility toanswer questions.

What is involved in preparing a

meeting with industry, community,

and state representatives?

Meetings can be an effective means of giv-ing and receiving comments and addressingconcerns. To publicize a meeting, the date,time, and location of the meeting should beplaced in a local newspaper and/or advertisedon the radio. To help ensure a successful dia-logue, meetings should be at times conve-nient for members of the community, such asearly in the evenings during the week, or onweekends. An interpreter might need to beobtained if the local community includes resi-dents whose primary language is not English.

Prior to a meeting, the facility representa-tive should develop a waste management planor come to the meeting prepared to describehow the industrial waste from the facility willbe managed. A waste management plan pro-vides a starting point for public comment andinput. Keep data presentations simple andprovide information relevant to the audience.Public speakers should be able to respond toboth general and technical questions. Also,the facility representative should review andbe familiar with the concerns of groups or cit-izens who havepreviouslyexpressed aninterest in thefacility’s opera-tions. In addi-tion, it isimportant toanticipate ques-tions and planhow best torespond to thesequestions at ameeting.


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Methods Features Advantages Disadvantages

Briefings Personal visit or phone call to Provides background information. Requires time.key officials or group leaders to Determines reactions before an issue announce a decision, provide “goes public.” Alerts key people to background information, or issues that might affect them. answer questions.

Mailing of key Mailing technical studies or Provides full and detailed information Costs money to print and technical reports or environmental reports to other to people who are most interested. mail. Some people might not environmental agencies, leaders of organized Often increases the credibility of read the reports.documents groups, or other interested parties. studies because they are fully visible.

News conferences Brief presentation to reporters, Stimulates media interest in a story. Reporters will only come if followed by a question-and- Direct quotations often appear in the announcement or presen-answer period, often television and radio. Might draw tation is newsworthy. Cannot accompanied by handouts of attention to an announcement or control how the story is pre-presenter’s comments. generate interest in public meetings. sented, although some direct

quotations are likely.

Newsletters Brief description of what is going Provides more information than can Requires staff time. Costs on, usually issued at key intervals be presented through the media to money to prepare, print, and for all people who have shown those who are most interested. Often mail. Stories must be objec-interest. used to provide information prior to tive and credible, or people

public meetings or key decision points. will react to the newsletters Helps to maintain visibility during as if they were propaganda. extended technical studies.

Newspaper inserts Much like a newsletter, but Reaches the entire community with Requires staff time to prepare distributed as an insert in a important information. Is one of the the insert, and distribution newspaper. few mechanisms for reaching everyone costs money. Must be pre-

in the community through which you pared to newspaper’s layout can tell the story your way. specifications.

Paid advertisements Advertising space purchased in Effective for announcing meetings or Advertising space can be newspapers or on the radio or key decisions or as background costly. Radio and television television. material for future media stories. can entail expensive produc-

tion costs to prepare the ad.

News releases A short announcement or news Might stimulate interest from the Might be ignored or not story issued to the media to get media. Useful for announcing read. Cannot control how interest in media coverage of the meetings or major decisions or as the information is used. story. background material for future media

stories.

Presentations to civic Deliver presentations, enhanced Stimulates communication with key Few disadvantages, except and technical groups with slides or overheads, to key community groups. Can also provide some groups can be hostile.

community groups. in-depth responses.

Press kits A packet of information Stimulates media interest in the story. Few disadvantages, except distributed to reporters. Provides background information that cannot control how the

reporters can use for future stories. information is used and might not be read.

Advisory groups and A group of representatives of key Promotes communication between Potential for controversy task forces interested parties is established. key constituencies. Anticipates public exists if “advisory” recom-

Possibly a policy, technical, or reaction to publications or decisions. mendations are not followed.citizen advisory group. Provides a forum for reaching Requires substantial commit-

consensus. ment of staff time to provide support to committees.

Table 1Effective Methods for Public Notification

State representatives also should antici-pate and be prepared to answer questionsraised during the meeting. State representa-tives should be prepared to answer ques-tions on specific regulatory or complianceissues, as well as to address how the facilityhas been working in cooperation with thestate agency. The following are some ques-tions that are often asked at meetings.

• What are the risks to me associatedwith the operations?

• Who should I contact at the facility ifI have a question or concern?

• How will having the facility nearbybenefit the area?

• Will there be any noticeable day-to-day effects on the community?

• Which processes generate industrialwaste, and what types of waste aregenerated?

• How will the waste streams be treat-ed or managed?

• What are the construction plans forany proposed containment facilities?

• What are the intended methods formonitoring and detecting emissionsor potential releases?

• What are the plans to address acci-dental releases of chemicals or wastesat the site?

• What are the plans for financialassurance, closure, and post-closurecare?

• What are the applicable state regula-tions?

• How long will it take to issue thepermit?

• How will the permit be issued?

• Who should I contact at the stateagency if I have questions or con-cerns about the facility?

At the meeting, the facility representativeshould invite public and state comments onthe proposed change(s), and tell community


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U.S. EPA 1990. Sites for Our Solid Waste: A Guidebook for Effective Public Involvement.

Methods Features Advantages Disadvantages

Focus groups Small discussion groups Provides in-depth reaction to ideas or Gets reactions, but no established to give “typical” decisions. Good for predicting knowledge of how many reactions of the public. emotional reactions people share those reactions. Conducted by a professional Might be perceived as an facilitator. Several sessions can be effort to manipulate the conducted with different groups. public.

Telephone line Widely advertised phone number Gives people a sense that they know Is only as effective as the that handles questions or provides whom to call. Provides a one-step person answering the tele-centralized source of information. service of information. Can handle phone. Can be expensive.

two-way communication.

Meetings Less formal meetings for people Highly legitimate forum for the public Unless a small-group discus-to present positions, ask to be heard on issues. Can be sion format is used, it permitsquestions, and so forth. structured to permit small group only limited dialogue. Can

interaction— anyone can speak. get exaggerated positions or grandstanding. Requires staff time to prepare for meetings.

Table 1Effective Methods for Public Notification (cont.)

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members where, and to whom, they shouldsend written comments. A facility can chooseto respond to comments in several ways. Forexample, telephone calls, additional factsheets, or additional meetings can all be usedto address comments. Responding promptlyto residents’ comments and concerns demon-strates an honest attempt to address them.

C. Make Knowledgeableand Responsible PeopleAvailable for SharingInformation

Having a facility representative available toanswer the public’s questions and provideinformation helps assure citizens that thefacility is actively listening to their concerns.Having a state contact available to address thepublic’s concerns about the facility can alsomake sure that concerns are being heard andaddressed.

In addition to identifying a contact person,facilities and states should consider setting upa telephone line staffed by employees for citi-zens to call and obtain information promptlyabout the facility. Opportunities for face-to-face interaction between community mem-bers and facility representatives include onsiteinformation offices, open houses, workshops,

or briefings.Informationoffices functionsimilarly to infor-mation reposito-ries, except thatan employee ispresent to answerquestions. Openhouses are infor-mal meetings onsite where resi-dents can talk tocompany officials

one-to-one. Similarly, workshops and briefin-gs enable community members, state officials,and facility representatives to interact, askquestions, and learn about the activities at thefacility. Web sites can also serve as a usefultool for facility, state, and community repre-sentatives to share information and ask ques-tions.

D. Provide InformationAbout FacilityOperations

Providing information about facility opera-tions is an invaluable way to help the publicunderstand waste management activities.Methods of informing communities includeconducting facility tours; maintaining a pub-licly accessible information repository on siteor at a convenient offsite public building suchas a library; developing exhibits to explainoperations; and distributing informationthrough the publications of established orga-nizations. Examples of public involvementactivities are presented in the following pages.

Conduct facility tours. Scheduled facilitytours allow community members and staterepresentatives to visit the facility and askquestions about how it operates. By seeing afacility first-hand, residents learn how wasteis managed and can become more confidentthat it is being managed safely. Individual cit-izens, local officials, interest groups, students,and the media might want to take advantageof facility tours. In planning tours, determinethe maximum number of people that can betaken through the facility safely and think ofways to involve tour participants in what theyare seeing, such as providing hands-ondemonstrations. It is also a good idea to havefacility representatives available to answertechnical questions in an easy-to-understandmanner.

Maintain a publicly accessible informa-tion repository. An information repository issimply a collection of documents describingthe facility and its activities. It can includebackground information on the facility, thepartnership plan (if developed), permits tomanage waste on site, fact sheets, and copiesof relevant guidance and regulations. Therepository should be in a convenient, publiclyaccessible place. Repositories are often main-tained on site in a public “reading room” oroff site at a public library, town hall, or publichealth office. Facilities should publicize theexistence, location, and hours of the reposito-ry and update the information regularly.

Develop exhibits that explain facilityoperations. Exhibits are visual displays, suchas maps, charts, diagrams, or photographs,accompanied by brief text. They can providetechnical information in an easily under-standable way and an opportunity to illus-trate creatively and informatively issues of

concern. When developing exhibits, identifythe target audience, clarify which issue oraspect of the facility’s operations will be theexhibit’s focus, and determine where theexhibit will be displayed. Public libraries,convention halls, community events, andshopping centers are all good, highly visiblelocations for an exhibit.

Use publications and mailing lists ofestablished local organizations. Existinggroups and publications often provide accessto established communication networks. Takeadvantage of these networks to minimize thetime and expense required to develop mailinglists and organize meetings. Civic or environ-mental groups, rotary clubs, religious organi-zations, and local trade associations mighthave regular meetings, newsletters, newspa-pers, magazines, or mailing lists that could beuseful in reaching interested members of thecommunity.


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1-18


American Chemistry Council’sResponsible Care®

To address citizens’ concerns about the manu-facture, transport, use, and disposal of chemicalproducts, the American Chemistry Council (ACC)launched its Responsible Care® program in 1988.To maintain their membership in ACC, companiesmust participate in the Responsible Care® pro-gram. One of the key components of the programis recognizing and responding to community con-cerns about chemicals and facility operations.

ACC member are committed to fostering anopen dialogue with residents of the communities inwhich they are located. To do this, member compa-nies are required to address community concerns intwo ways: (1) by developing and maintaining com-munity outreach programs, and (2) by assuring thateach facility has an emergency response program inplace. For example, member companies provideinformation about their waste minimization andemissions reduction activities, as well as provideconvenient ways for citizens to become familiarwith the facility, such as tours. Many companiesalso set up Community Advisory Panels. Thesepanels provide a mechanism for dialogue on issuesbetween plants and local communities. Companiesmust also develop written emergency responseplans that include information about how to com-municate with members of the public and considertheir needs after an emergency.

Responsible Care® is just one example of howpublic involvement principles can be incorporatedinto everyday business practices. The program alsoshows how involving the public makes good busi-ness sense. For more information aboutResponsible Care®, contact ACC at 703 741-5000.

AF&PA’s Sustainable ForestryInitiative

Public concern about the future of America’sforests coupled with the American Forest & Paper

Association’s (AF&PA’s) belief that “sound environ-mental policy and sound business practice go handin hand” fueled the establishment of theSustainable Forestry Initiative (SFI). Established in1995, the SFI outlines principles and objectives forenvironmental stewardship with which all AF&PAmembers must comply in order to retain member-ship. SFI encourages protecting wildlife habitatand water quality, reforesting harvested land, andconserving ecologically sensitive forest land. SFIrecognizes that continuous public involvement iscrucial to its ultimate goal of “ensuring that futuregenerations of Americans will have the same abun-dant forests that we enjoy today.”

The SFI stresses the importance of reaching outto the public through toll-free information lines,environmental education, private and public sectortechnical assistance programs, workshops, videos,and other means. To help keep the publicinformed of achievements in sustainable forestry,members report annually on their progress, andAF&PA distributes the resulting publication tointerested parties. In addition, AF&PA runs twonational forums a year, which bring together log-gers, landowners, and senior industry representa-tives to review progress toward SFI objectives.

Many AF&PA state chapters have developedadditional activities to inform the public about theSFI. For example, in New Hampshire, AF&PApublished a brochure about sustainable forestryand used it to brief local sawmill officials and themedia. In Vermont, a 2-hour interactive televisionsession allowed representatives from industry, pub-lic agencies, environmental organizations, the aca-demic community, and private citizens to sharetheir views on sustainable forestry. Furthermore, inWest Virginia, AF&PA formed a Woodland OwnerEducation Committee to reach out to nonindustrialprivate landowners.

For more information about the SFI, contactAF&PA at 800 878-8878, or visit the Web site<www.afandpa.org>.


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You should consider the following activities in understanding risk and building partnerships betweenfacilities, states, and community members when addressing potential waste management practices.

■■■■ Understand the definition of risk.

■■■■ Review sources for obtaining health benchmarks.

■■■■ Understand the risk assessment process including the pathways and routes of potential exposureand how to quantify or estimate exposure.

■■■■ Be familiar with the risk assessment process for cancer risks and non-cancer risks.

■■■■ Develop exhibits that provide a better understanding of facility operations.

■■■■ Identify potentially interested/affected people.

■■■■ Notify the state and public about new facilities or significant changes in facility operating plans.

■■■■ Set up a public meeting for input from the community.

■■■■ Provide interpreters for public meetings.

■■■■ Make knowledgeable and responsible people available for sharing information.

■■■■ Develop a partnership plan based on information gathered in previous steps.

■■■■ Provide tours of the facility and information about its operations.

■■■■ Maintain a publicly accessible information repository or onsite reading room.

■■■■ Develop environmental risk communication skills.

Understanding Risk and BuildingPartnerships Activity List

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American Chemistry Council. 2001 Guide to Community Advisory Panels.

American Chemistry Council. Revised 2001. Environmental Justice and Your Community: A PlantManager’s Introduction.

American Chemistry Council. Responsible Care® Overview Brochure.

Council in Health and Environmental Science, ENVIRON Corporation. 1986. Elements of Toxicologyand Chemical Risk Assessment.

Executive Order 12898. 1994. Federal Actions to Address Environmental Justice in MinorityPopulations and Low-income Populations. February.

Holland, C.D., and R.S. Sielken, Jr. 1993. Quantitative Cancer Modeling and Risk Assessment.

Kolluru, Rao, Steven Bartell, et al. 1996. Risk Assessment and Management Handbook: ForEnvironmental, Health, and Safety Professionals.

Louisiana Department of Environmental Quality. 1994. Final Report to the Louisiana Legislature onEnvironmental Justice.

Lu, Frank C. 1996. Basic Toxicology: Fundamentals, Target Organs, and Risk Assessment.

National Research Council. 1983. Risk Assessment in the Federal Government: Managing the Process.

Public Participation and Accountability Subcommittee of the National Environmental Justice AdvisoryCouncil (A Federal Advisory Committee to the U.S. EPA). 1996. The Model Plan for PublicParticipation. November.

Texas Natural Resource Conservation Commission. 1993. Texas Environmental Equity and Justice TaskForce Report: Recommendations to the Texas Natural Resource Conservation Commission.

Travis, C.C. 1988. Carcinogenic Risk Assessment.

U.S. EPA. 1996a. RCRA Public Involvement Manual. EPA530-R-96-007.

Resources


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U.S. EPA. 1996b. 1994 Toxics Release Inventory: Public Data Release, Executive Summary. EPA745-S-96-001.

U.S. EPA. 1995a. Decision-maker’s Guide to Solid Waste Management, Second Edition. EPA530-R-95-023.

U.S. EPA. 1995b. The Exposure Factors Handbook. EPA600-P-95-002A-E.

U.S. EPA. 1995c. OSWER Environmental Justice Action Agenda. EPA540-R-95-023.

U.S. EPA. 1992. Environmental Equity: Reducing Risk for all Communities. EPA230-R-92-008A.

U.S. EPA. 1990. Sites for our Solid Waste: A Guidebook for Effective Public Involvement. EPA530-SW-90-019.

U.S. EPA. 1989a. Chemical Releases and Chemical Risks: A Citizen’s Guide to Risk Screening. EPA560-2-89-003.

U.S. EPA. 1989b. Risk Assessment Guidance for Superfund. EPA540-1-89-002.

U.S. Government Accounting Office. 1995. Hazardous and Nonhazardous Waste: Demographics ofPeople Living Near Waste Facilities. GAO/RCED-95-84.

Ward, R. 1995. Environmental Justice in Louisiana: An Overview of the Louisiana Department ofEnvironmental Quality’s Environmental Justice Program.

Western Center for Environmental Decision-Making. 1996. Public Involvement in Comparative RiskProjects: Principles and Best Practices: A Source Book for Project Managers.

Resources (cont.)

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Appendix


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Chapter 2 Characterizing Waste

Contents

I. Waste Characterization Through Process Knowledge ..............................................................................2 - 2

II. Waste Characterization Through Leachate Testing ..................................................................................2 - 3

A. Sampling and Analysis Plan ..................................................................................................................2 - 4

1. Representative Waste Sampling..........................................................................................................2 - 6

2. Representative Waste Analysis ..........................................................................................................2 - 8

B. Leachate Test Selection ..........................................................................................................................2 - 9

1. Toxicity Characteristic Leaching Procedure (TCLP) ........................................................................2 - 10

2. Synthetic Precipitation Leaching Procedure (SPLP)..........................................................................2 - 11

3. Multiple Extraction Procedure (MEP) ..............................................................................................2 - 12

4. Shake Extraction of Solid Waste with Water or Neutral Leaching Procedure ..................................2 - 13

III. Waste Characterization of Volatile Organic Emissions ..........................................................................2 - 13

Waste Characterization Activity List ............................................................................................................2 - 15

Resources ....................................................................................................................................................2 - 16

Appendix ....................................................................................................................................................2 - 18

Getting Started—Characterizing Waste

2-1

Understanding the physical andchemical properties of a wasteusing sampling and analysistechniques is the cornerstoneupon which subsequent steps in

the Guide are built. It is necessary for gaugingwhat risks a waste might pose to surface water,ground water, and air and drives waste man-agement unit design and operating decisions.Knowing the composition of the waste is alsonecessary when determining the constituentsfor which to test. And, as discussed in Chapter3–Integrating Pollution Prevention, knowledgeof the physical and chemical properties of thewaste is crucial in identifying pollution pre-vention opportunities.

In many instances, you can use knowledgeof waste generation processes, analytical test-

ing, or some combination of the two to esti-mate waste generation rates and waste con-stituent concentrations. To the extent that thewaste is not highly variable, the use of processknowledge can be a sound approach to wastecharacterization and can prove more reason-able and cost effective than frequent samplingof the waste. It is important to note, however,that owners or operators using process knowl-edge to characterize a waste in lieu of testingare still responsible for the accuracy of theirdeterminations. No matter what approach isused in characterizing a waste, the goal is tomaximize the available knowledge that is nec-essary to make the important decisionsdescribed in later chapters of the Guide. Also,as changes are made to the industrial process-es or waste management practices, it might benecessary to recharacterize a waste in order toaccurately make waste management decisionsand evaluate risk.

In considering the use of process knowl-edge or analytical testing, it is important tonote that the ground water and air emissionsmodels that accompany the Guide use con-stituent concentrations to estimate risk. Inputrequires specific concentrations which cannotbe precisely estimated solely by knowledge ofthe processes that generate the waste. Further,when wastes are placed in a waste manage-ment unit, such as a landfill or surface

Characterizing WasteThis chapter will help you:

• Understand the industrial processes that generate a waste.

• Determine the waste’s physical and chemical properties.

• Estimate constituent leaching to facilitate ground-water risk analysis.

• Quantify total constituent concentrations to facilitate air emissions

analysis.

This chapter will help you address thefollowing questions:

• How can process knowledge be usedto characterize a waste?

• Which constituent concentrationsshould be quantified?

• Which type of leachate test should beused?

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impoundment, they are subjected to variousphysical, chemical, and biological processesthat can result in the creation of new com-pounds in the waste, changes in the mass andvolume of the waste, and the creation of dif-ferent phases within the waste and within thelandfill or impoundment. In order to accu-rately predict the concentration of the conta-minants in the leachate, these changes mustbe accounted for.

Accurate waste management unit con-stituent characterization is also necessary forinput to the modeling tools provided in theGuide. Because model input requires specificdata, model output will be based on the accu-racy of the data input. Process knowledgealone (unless based on previous testing) mightnot be sufficiently accurate to yield reliableresults. Leachate testing (discussed later inthis chapter), for example, will likely give youa more precise assessment of waste con-stituent concentrations than process knowl-edge. Also note that whether you are usingprocess knowledge, testing, or a combinationof both, sources of model input data must bewell documented so that an individual evalu-ating the modeling results understands thebackground supporting the assessment.

I. WasteCharacterizationThrough ProcessKnowledge

A waste characterization begins with anunderstanding of the industrial processes thatgenerate a waste. You must obtain enoughinformation about the process to enableproper characterization of the waste, forexample, by reviewing process flow diagramsor plans and determining all inputs and out-puts. You should also be familiar with other

waste characteristics such as the physicalstate of the waste, the volume of waste pro-duced, and the general composition of thewaste. In addition, many industries havethoroughly tested and characterized theirwastes over time, therefore it might be benefi-cial to contact your trade association to deter-mine if waste characterizations have alreadybeen performed and are available for process-es similar to yours. Additional resources canassist in waste characterization by providinginformation on waste constituents and poten-tial concentrations. Some examples include:

• Chemical engineering designs orplans for the process, showingprocess input chemicals, expectedprimary and secondary chemicalreactions, and products.

• Material Safety Data Sheets (MSDSs)for materials involved. (Note that notall MSDSs contain information on allconstituents found in a product.)

• Manufacturer’s literature.

• Previous waste analyses.

• Literature on similar processes.

• Preliminary testing results, if available.

A material balance exercise using processknowledge can be useful in understandingwhere wastes are generated within a processand in estimating concentrations of waste con-stituents particularly where analytical test data


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are limited. In a material balance, all inputstreams, such as raw materials fed into theprocesses, and all output streams, such asproducts produced and waste generated, arecalculated. Flow diagrams can be used to iden-tify important process steps and sources wherewastes are generated. Characterizing wastesusing material balances can require consider-able effort and expense, but can help you todevelop a more complete picture of the wastegeneration process(es) involved.

Note that a thorough assessment of yourproduction processes can also serve as thestarting point for facility-wide waste reduc-tion, recycling, or pollution preventionefforts. Such an assessment will provide theinformation base to explore many opportuni-ties to reduce or recycle the volume or toxici-ty of wastes. Refer to Chapter 3–IntegratingPollution Prevention for ideas, tools, and ref-erences on how to proceed.

While the use of process knowledge isattractive because of the cost savings associat-ed with using existing information, you mustensure that this information accurately char-acterizes your wastes. If using processdescriptions, published data, and document-ed studies to determine waste characteristics,the data should be scrutinized carefully todetermine if there are any differences betweenthe processes in the studies and the wastegenerating process at your facility, that thestudies are acceptable and accurate (i.e.,based on valid sampling and analytical tech-niques), and that the information is current.

If there are discrepancies, or if you begin anew process or change any of the existingprocesses at your facility (so that the docu-mented studies and published data are nolonger applicable), you are encouraged toconsider performing additional sampling andlaboratory analysis to accurately characterizethe waste and ensure proper management.Also, if process knowledge is used in addition

to, or in place of, sampling and analysis, youshould clearly document the informationused in your characterization assessment todemonstrate to regulatory agencies, the pub-lic, and other interested parties that the infor-mation accurately and completelycharacterizes the waste. The source of thisinformation should be clearly documented.

II. WasteCharacterizationThroughLeachate Testing

Although sampling and laboratory analysisis not as economical and might not be asconvenient as using process knowledge, itdoes have advantages. The resulting data usu-ally provide the most accurate informationavailable on constituent concentration levels.

What is processknowledge?Process knowledge refers to detailedinformation on processes that generatewastes. It can be used to partly, or inmany cases completely, characterizewaste to ensure proper management.Process knowledge includes:

• Existing published or documentedwaste analysis data or studies con-ducted on wastes generated byprocesses similar to that which gener-ated the waste.

• Waste analysis data obtained fromother facilities in the same industry.

• Facility’s records of previously per-formed analyses.

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Incomplete or mis-characterization of wastecan lead to improper waste management, inac-curate modeling outputs, or erroneous deci-sions concerning the type of unit to be used,liner selection, or choice of land applicationmethods. Note that process knowledge allowsyou to eliminate unnecessary or redundantwaste testing by helping you focus on whichconstituents to measure in the waste. Again,thorough documentation of both the processknowledge used (e.g., studies, published data),as well as the analytical data is important.

The intent of leachate and extraction testingis to estimate the leaching potential of con-stituents of concern to water sources. It isimportant to estimate leaching potential inorder to accurately estimate the quantity ofchemicals that could potentially reach ground-or surface-water resources (e.g., drinkingwater supply wells, waters used for recre-ation). The Industrial Waste ManagementEvaluation Model (IWEM) developed for theGuide uses expected leachate concentrationsfor the waste management units as the basisfor liner system design recommendations.Leachate tests will allow you to accuratelyquantify the input terms for modeling.

If the total concentration of all the con-stituents in a waste has been estimated usingprocess knowledge (which could include pre-vious testing data on wastes known to be verysimilar), estimates of the maximum possibleconcentration of these constituents in leachatecan be made using the dilution ratio of theleachate test to be performed.

For example, the Toxicity CharacteristicLeachate Procedure (TCLP) allows for a totalconstituent analysis in lieu of performing thetest for some wastes. If a waste is 100 percentsolid, as defined by the TCLP method, then

the results of the total compositional analysismay be divided by twenty to convert the totalresults into the maximum leachable concentra-tion1. This factor is derived from the 20:1 liq-uid to solid ratio employed in the TCLP. Thisis a conservative approach to estimatingleachate concentrations and does not factor inenvironmental influences, such as rainfall. If awaste has filterable liquid, then the concentra-tion of each phase (liquid and solid) must bedetermined. The following equation may beused to calculate this value:2

(V1)(C1) + (V2)(C2)

V1 + 20V2

Where:

V1 = Volume of the first phase (L)

C1 = Concentration of the analyte of con-cern in the first phase (mg/L)

V2 = Volume of the second phase (L)

C2 = Concentration of the analyte of con-cern in the second phase (mg/L)

Because this is only a screening method foridentifying an upper-bound TCLP leachateconcentration, you should consult with yourstate or local regulatory agency to determinewhether process knowledge can be used toaccurately estimate maximum risk in lieu ofleachate testing.

A. Sampling and AnalysisPlan

One of the more critical elements in properwaste characterization is the plan for samplingand analyzing the waste. The sampling plan isusually a written document that describes theobjectives and details of the individual tasks of

1 This method is only appropriate for estimating maximum constituent concentration in leachate for non-liquid wastes (e.g., those wastes not discharged to a surface impoundment). For surface impoundments,the influent concentration of heavy metals can be assumed to be the maximum theoretical concentrationof metals in the leachate for purposes of input to the ground-water modeling tool that accompanies thisdocument. To estimate the leachate concentration of organic constituents in liquid wastes for modelinginput, you will need to account for losses occurring within the surface impoundment before you can esti-mate the concentration in the leachate (i.e., an effluent concentration must be determined for organics).

2 Source: Office of Solid Waste Web site at <www.epa.gov/sw-846/sw846.htm>.


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a sampling effort and how they will be per-formed. This plan should be carefully thoughtout, well in advance of sampling. The moredetailed the sampling plan, the less opportu-nity for error or misunderstanding duringsampling, analysis, and data interpretation.

To ensure that the sampling plan isdesigned properly, a wide range of personnelshould be consulted. It is important that thefollowing individuals are involved in thedevelopment of the sampling plan to ensurethat the results of the sampling effort are pre-cise and accurate enough to properly charac-terize the waste:

• An engineer who understands themanufacturing processes.

• An experienced member of the sam-pling team.

• The end user of the data.

• A senior analytical chemist.

• A statistician.

• A quality assurance representative.

It is also advisable that you consult theanalytical laboratory to be used when devel-oping your sampling plan.

Background information on the processesthat generate the waste and the type andcharacteristics of the waste management unitis essential for developing a sound samplingplan. Knowledge of the unit location and sit-uation (e.g., geology, exposure of the waste tothe elements, local climatic conditions) willassist in determining correct sample size andsampling method. Sampling plan design willdepend on whether you are sampling a wasteprior to disposal in a waste management unitor whether you are sampling waste from anexisting unit. When obtaining samples froman existing unit, care should be taken toavoid endangering the individuals collectingthe samples and to prevent damaging the unit

itself. Reasons for obtaining samples from anexisting unit include, characterizing the wastein the unit to determine if the new wastebeing added is compatible, checking to see ifthe composition of the waste is changing overtime due to various chemical and biologicalbreakdown processes, or characterizing thewaste in the unit or the leachate from theunit to give an indication of expected concen-trations in leachate from a new unit.

The sampling plan must be correctlydefined and organized in order to get anaccurate estimation of the characteristics ofthe waste. Both an appropriate sample sizeand proper sampling techniques are neces-sary. If the sampling process is carried outcorrectly, the sample will be representativeand the estimates it generates will be usefulfor making decisions concerning proper man-agement of the waste and for assessing risk.

In developing a sampling plan, accuracy isof primary concern. The goal of sampling is toget an accurate estimate of the waste’s charac-teristics from measuring the sample’s charac-teristics. The main controlling factor indeciding whether the estimates will be accu-rate is how representative the sample is (dis-cussed in the following section). Using a smallsample increases the possibility that the sam-ple will not be representative, but a samplethat is larger than the minimum calculatedsample size does not necessarily increase theprobability of getting a representative sample.

As you are developing the sampling plan, youshould address the following considerations:

• Data quality objectives.

• Determination of a representativesample.

• Statistical methods to be employed inthe analyses.

• Waste generation and handlingprocesses.

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• Constituents/parameters to be sampled.

• Physical and chemical properties ofthe waste.

• Accessibility of the unit.

• Sampling equipment, methods, andsample containers.

• Quality assurance and quality control(e.g., sample preservation and han-dling requirements).

• Chain-of-custody.

• Health and safety of employees.

Many of these considerations are discussedbelow. Additional information on data qualityobjectives and quality assurance and qualitycontrol can be found in Test Methods forEvaluating Solid Waste, Physical/ChemicalMethods—SW-846 (U.S. EPA, 1996e), Guidancefor the Data Quality Objectives Process (U.S.EPA, 1996b), Guidance on Quality AssuranceProject Plans (U.S. EPA, 1998a), and Guidancefor the Data Quality Assessment: PracticalMethods for Data Analysis (U.S. EPA, 1996a).3

A determination as to the constituents thatwill be measured can be based on processknowledge to narrow the focus and expenseof performing the analyses. Analyses shouldbe performed for those constituents that arereasonably expected to be in the waste atdetectable levels (i.e., test method detectionlevels). Note that the Industrial WasteManagement Evaluation Model (IWEM) thataccompanies this document recommendsliner system designs, if necessary, or theappropriateness of land application based oncalculated protective leachate thresholds(Leachate Concentration Threshold Values orLCTVs) for various constituents that are like-ly to be found in industrial waste and posehazards at certain levels to people and theenvironment. The constituents that are evalu-ated are listed in Table 1.2 of the IndustrialWaste Management Evaluation Model Technical

Background Document (U.S. EPA 2002). TheLCTV tables also are included in the IWEMTechnical Background Document and the modelon the CD-ROM version of this Guide, andcan be used as a starting point to help youdetermine which constituents to measure. Itis not recommended that you sample for allof the organic chemicals and metals listed inthe tables, but rather use these tables as aguide in conjunction with knowledge con-cerning the waste generating practices todetermine which constituents to measure.

1. Representative WasteSampling

The first step in any analytical testingprocess is to obtain a sample that is represen-tative of the physical and chemical composi-tion of a waste. The term “representativesample” is commonly used to denote a samplethat has the same properties and compositionin the same proportions as the populationfrom which it was collected. Finding one sam-ple which is representative of the entire wastecan be difficult unless you are dealing with ahomogenous waste. Because most industrialwastes are not homogeneous, many differentfactors should be considered in obtainingsamples. Examples of some of the factors thatshould be considered include:

• Physical state of the waste. Thephysical state of the waste affectsmost aspects of a sampling effort. Thesampling device will vary accordingto whether the sample is liquid, solid,gas, or multiphasic. It will also varyaccording to whether the liquid isviscous or free-flowing, or whetherthe solid is hard, soft, powdery,monolithic, or clay-like.

• Composition of the waste. Thesamples should represent the averageconcentration and variability of thewaste in time or over space.

3 These and other EPA publications can be found at the National Environmental Publications Internetsite (NEPIS) at <www.epa.gov/ncepihom/nepishom/>.


2-7

• Waste generation and han-dling processes. Processes toconsider include: if the wasteis generated in batches; ifthere is a change in the rawmaterials used in a manufac-turing process; if waste com-position can vary substantiallyas a function of process tem-peratures or pressures; and ifstorage time affects the waste’scharacteristics/composition.

• Transitory events. Start-up,shut-down, slow-down, andmaintenance transients canresult in the generation of awaste that is not representativeof the normal waste stream. Ifa sample was unknowinglycollected at one of these inter-vals, incorrect conclusionscould be drawn.

You should consult with your state orlocal regulatory agency to identify anylegal requirements or preferences beforeinitiating sampling efforts. Refer toChapter 9 of the EPA’s SW-846 testmethods document (see side bar) fordetailed guidance on planning, imple-menting, and assessing sampling events.

To ensure that the chemical infor-mation obtained from waste samplingefforts is accurate, it must be unbiasedand sufficiently precise. Accuracy isusually achieved by incorporatingsome form of randomness into thesample selection process and by select-ing an appropriate number of samples.Since most industrial wastes are het-erogeneous in terms of their chemicalproperties, unbiased samples andappropriate precision can usually beachieved by simple random sampling.In this type of sampling, all units inthe population (essentially all locations

More information on Test Methodsfor Evaluating Solid Waste, Physical/Chemical Methods—SW-846

EPA has begun replacing requirements mandat-ing the use of specific measurement methods ortechnologies with a performance-based measure-ment system (PBMS). The goal of PBMS is toreduce regulatory burden and foster the use ofinnovative and emerging technologies or meth-ods. The PBMS establishes what needs to beaccomplished, but does not prescribe specificallyhow to do it. In a sampling situation, for exam-ple, PBMS would establish the data needs, thelevel of uncertainty acceptable for making deci-sions, and the required supporting documenta-tion; a specific test method would not beprescribed. This approach allows the analyst theflexibility to select the most appropriate and costeffective test methods or technologies to complywith the criteria. Under PBMS, the analyst isrequired to demonstrate the accuracy of the mea-surement method using the specific matrix that isbeing analyzed. SW-846 serves only as a guidancedocument and starting point for determiningwhich test method to use.

SW-846 provides state-of-the-art analytical testmethods for a wide array of inorganic and organicconstituents, as well as procedures for field andlaboratory quality control, sampling, and charac-teristics testing. The methods are intended to pro-mote accuracy, sensitivity, specificity, precision,and comparability of analyses and test results.

For assistance with the methods described in SW-846, call the EPA Method InformationCommunication Exchange (MICE) Hotline at 703676-4690 or send an e-mail to [email protected].

The text of SW-846 is available online at:<www.epa.gov/sw-846/main.htm>. A hard copyor CD-ROM version of SW-846 can be purchasedby calling the National Technical InformationService (NTIS) at 800 553-6847.

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or points in all batches of waste from which asample could be collected) are identified, anda suitable number of samples is randomlyselected from the population.

The appropriate number of samples toemploy in a waste characterization is at leastthe minimum number of samples required togenerate a precise estimate of the true meanconcentration of a chemical contaminant in awaste. A number of mathematical formulasexist for determining the appropriate numberof samples depending on the statistical preci-sion required. Further information on sam-pling designs and methods for calculatingrequired sample sizes and optimal distribu-tion of samples can be found in Gilbert(1987), Winer (1971), and Cochran (1977)and Chapter 9 of EPA SW-846.

The type of sampling plan developed willvary depending on the sampling location.Solid wastes contained in a landfill or wastepile can be best sampled using a three-dimensional random sampling strategy. Thisinvolves establishing an imaginary three-dimensional grid or sampling points in thewaste and then using random-number tablesor random-number generators to select pointsfor sampling. Hollow-stem augers combinedwith split-spoon samplers are frequentlyappropriate for sampling landfills.

If the distribution of waste components isknown or assumed for liquid or semi-solidwastes in surface impoundments, then a two-dimensional simple random sampling strategymight be appropriate. In this strategy, the topsurface of the waste is divided into an imagi-nary grid and grid sections are selected usingrandom-number tables or random-numbergenerators. Each selected grid point is thensampled in a vertical manner along the entirelength from top to bottom using a samplingdevice such as a weighted bottle, a drumthief, or Coliwasa.

If sampling is restricted, the sampling strat-egy should, at a minimum, take sufficientsamples to address the potential vertical varia-tions in the waste in order to be consideredrepresentative. This is because containedwastes tend to display vertical, rather thanhorizontal, non-random heterogeneity due tosettling or the layering of solids and denserliquid phases. Also, care should be takenwhen performing representative sampling of alandfill, waste pile, or surface impoundmentto minimize any potential to create hazardousconditions. (It is possible that the improperuse of intrusive sampling techniques, such asthe use of augers, could accelerate leaching bycreating pathways or tunnels that can acceler-ate leachate movement to ground water.)

To facilitate characterization efforts, consultwith state and local regulatory agencies and aqualified professional to select a sampling planand determine the appropriate number of sam-ples, before beginning sampling efforts. Youshould also consider conducting a detailedwaste-stream specific characterization so thatthe information can be used to conduct wastereduction and waste minimization activities.

Additional information concerning sam-pling plans, strategies, methods, equipment,and sampling quality assurance and qualitycontrol is available in Chapters 9 and 10 of theSW-846 test methods document. Electronicversions of these chapters have been includedon the CD-ROM version of the Guide.

2. Representative Waste AnalysisAfter a representative sample has been col-

lected, it must be properly preserved to main-tain the physical and chemical properties thatit possessed at the time of collection. Sampletypes, sample containers, container prepara-tion, and sample preservation methods arecritical for maintaining the integrity of thesample and obtaining accurate results.Preservation and holding times are also


2-9

4 There are several general categories of phases in which samples can be categorized: solids, aqueous,sludges, multiphase samples, ground water, and oil and organic liquid. You should select a test that isdesigned for the specific sample type.

important factors to consider and will varydepending on the type of constituents beingmeasured (e.g., VOCs, heavy metals, hydro-carbons) and the waste matrix (e.g., solid,liquid, semi-solid).

The analytical chemist then develops ananalytical plan which is appropriate for thesample to be analyzed, the constituents to beanalyzed, and the end use of the informationrequired. The laboratory should have standardoperating procedures available for review forthe various types of analyses to be performedand for all associated methods needed to com-plete each analysis, such as instrument main-tenance procedures, sample handlingprocedures, and sample documentation proce-dures. In addition, the laboratory should havea laboratory quality assurance/quality controlstatement available for review which includesall key personnel qualifications.

The SW-846 document contains informa-tion on analytical plans and methods.Another useful source of information regard-ing the selection of analytical methods andquality assurance/quality control proceduresfor various compounds is the Office of SolidWaste Methods Team home page at<www.epa.gov/sw-846/index.htm>.

B. Leachate Test SelectionLeaching tests are used to estimate poten-

tial concentration or amount of waste con-stituents that can leach from a waste toground water. Typical leaching tests use aspecified leaching fluid mixed with the solidportion of a waste for a specified time. Solidsare then separated from the leaching solutionand the solution is tested for waste con-stituent concentrations. The type of leachingtest performed can vary depending on thechemical, biological, and physical characteris-tics of the waste; the environment in whichthe waste will be placed; as well as the rec-

ommendations or requirements of your stateand local regulatory agencies.

When selecting the most appropriate ana-lytical tests, consider at a minimum the phys-ical state of the sample, the constituents to beanalyzed, detection limits, and the specifiedholding times of the analytical methods.4 Itmight not be cost-effective or useful to con-duct a test with detection limits at or greaterthan the constituent concentrations in awaste. Process knowledge can help you pre-dict whether the concentrations of certainconstituents are likely to fall below the detec-tion limits for anticipated methods.

After assessing the state of the waste, assessthe environment of the waste managementunit in which the waste will be placed. Forexample, an acidic environment mightrequire a different test than a non-acidic envi-ronment in order to best reflect the condi-tions under which the waste will actuallyleach. If the waste management unit is amonofill, then the characteristics of the wastewill determine most of the unit’s conditions.Conversely, if many different wastes are beingco-disposed, then the conditions created by

Which leaching test isappropriate?

Selecting an appropriate leachate testcan be summarized in the following foursteps:

1. Assess the physical state of the wasteusing process knowledge.

2. Assess the environment in which thewaste will be placed.

3. Consult with your state and/or localregulatory agency.

4. Select an appropriate leachate testbased on the above information.

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5 EPA has only reviewed and evaluated those test methods found in SW-846. The EPA has not reviewedor evaluated the other test methods and cannot recommend use of any test methods other than thosefound in SW-846.

6 EPA is undertaking a review of the TCLP test and how it is used to evaluate waste leaching (describedin the Phase IV Land Disposal Restrictions rulemaking, 62 Federal Register 25997; May 26, 1998). EPAanticipates that this review will examine the effects of a number of factors on leaching and onapproaches to estimating the likely leaching of a waste in the environment. These factors include pH,liquid to solid ratios, matrix effects and physical form of the waste, effects of non-hazardous salts onthe leachability of hazardous metal salts, and others. The effects of these factors on leaching might ormight not be well reflected in the leaching tests currently available. At the conclusion of the TCLPreview, EPA is likely to issue revisions to this guidance that reflect a more complete understanding ofwaste constituent leaching under a variety of management conditions.

7 The TCLP was developed to replace the Extraction Procedure Toxicity Test method which is designatedas EPA Method 1310 in SW-846.


the co-disposed wastes must be considered,including the constituents that can be leachedby the subject waste.

A qualified laboratory should always be usedwhen conducting analytical testing. The labora-tory can be in-house or independent. Whenusing independent laboratories, ensure thatthey are qualified and competent to performthe required tests. Some laboratories might beproficient in one test but not another. Youshould consult with the laboratory before final-izing your test selection to make certain thatthe test can be performed. When using analyti-cal tests that are not frequently performed,additional quality assurance and quality controlpractices might need to be implemented toensure that the tests are conducted correctlyand that the results are accurate.

A brief summary of the TCLP and threeother commonly used leachate tests is provid-ed below (procedures for the EPA test meth-ods are included in SW-846 and for theASTM method in the Annual Book of ASTMStandards). These summaries are provided asbackground and are not meant to imply thatthese are the only tests that can be used toaccurately predict leachate potential. Otherleachate tests have been developed and mightbe suitable for testing your waste. The tablein the appendix at the end of this chapterprovides a summary of over 20 leachate teststhat have been designed to estimate thepotential for contaminant release, includingseveral developed by ASTM.5 You should con-

sult with state and local regulatory agenciesand/or a laboratory that is familiar withleachate testing methods to identify the mostappropriate test and test method proceduresfor your waste and sample type.

1. Toxicity Characteristic LeachingProcedure (TCLP)

The TCLP 6 is the test method used to deter-mine whether a waste is hazardous due to itscharacteristics as defined in the ResourceConservation and Recovery Act (RCRA), 40CFR Part 261. The TCLP estimates the leacha-bility of certain toxicity characteristic hazardousconstituents from solid waste under a definedset of laboratory conditions. It evaluates theleaching of metals, volatile and semi-volatileorganic compounds, and pesticides fromwastes. The TCLP was developed to simulatethe leaching of constituents into ground waterunder conditions found in municipal solidwaste (MSW) landfills. The TCLP does not sim-ulate the release of contaminants to non-groundwater pathways. The TCLP is most commonlyused by EPA, state, and local agencies to classifywaste. It is also used to determine compliancewith some land disposal restrictions (LDRs) forhazardous wastes. The TCLP can be found asEPA Method 1311 in SW-846.7 A copy ofMethod 1311 has been included on the CD-ROM version of the Guide.

For liquid wastes, (i.e., those containingless than 0.5 percent dry solid material) thewaste after filtration through a glass fiber fil-

ter is defined as the TCLP extractant. Theconcentrations of constituents in the liquidextract are then determined.

For wastes containing greater than or equalto 0.5 percent solids, the liquid, if any, is sep-arated from the solid phase and stored forlater analysis. The solids must then bereduced to particle size, if necessary. Thesolids are extracted with an acetate buffersolution. A liquid-to-solid ratio of 20:1 byweight is used for an extraction period of 18± 2 hours. After extraction, the solids are fil-tered from the liquid through a glass fiber fil-ter and the liquid extract is combined withany original liquid fraction of the wastes.Analyses are then conducted on the liquid fil-trate/leachate to determine the constituentconcentrations.

To determine if a waste is hazardousbecause it exhibits the toxicity characteristic(TC), the TCLP method is used to generateleachate under controlled conditions as dis-cussed above. If the TCLP liquid extract con-tains any of the constituents listed in Table 1of 40 CFR Part 261 at a concentration equalto or greater than the respective value in thetable, the waste is considered to be a TC haz-ardous waste, unless exempted or excludedunder Part 261. Although the TCLP test wasdesigned to determine if a waste is hazardous,the importance of its use for waste characteri-zation as discussed in this chapter is tounderstand the parameters to be consideredin properly managing the wastes.

You should check with state and local reg-ulatory agencies to determine whether theTCLP is likely to be the best test for evaluat-ing the leaching potential of a waste or ifanother test might better predict leachingunder the anticipated waste managementconditions. Because the test was developed byEPA to determine if a waste is hazardous(according to 40 CFR 261.24) and focusedon simulating leaching of solid wastes placed

in a municipal landfill, this test might not beappropriate for your waste because the leach-ing potential for the same chemical can bequite different depending on a number of fac-tors. These factors include the characteristicsof the leaching fluid, the form of the chemicalin the solids, the waste matrix, and the dis-posal conditions.

Although the TCLP is the most commonlyused leachate test for estimating the actualleaching potential of wastes, you should notautomatically default to it in all situations orconditions and for all types of wastes. Whilethe TCLP test might be conservative undersome conditions (i.e., overestimates leachingpotential), it might underestimate leachingunder other extreme conditions. In a landfillthat has primarily alkaline conditions, theTCLP is not likely to be the optimal methodbecause the TCLP is designed to replicateleaching in an acidic environment. For mate-rials that pose their greatest hazard whenexposed to alkaline conditions (e.g., metalssuch as arsenic and antimony), use of theTCLP might underestimate the leachingpotential. When the conditions of your wastemanagement unit are very different from theconditions that the TCLP test simulates,another test might be more appropriate.Further, the TCLP might not be appropriatefor analyzing oily wastes. Oil phases can bedifficult to separate (e.g., it might be impossi-ble to separate solids from oil), oily materialcan obstruct the filter (often resulting in anunderestimation of constituents in theleachate), and oily materials can yield bothoil and aqueous leachate which must be ana-lyzed separately.8

2. Synthetic PrecipitationLeaching Procedure (SPLP)

The SPLP (designated as EPA Method 1312in SW-846) is currently used by several stateagencies to evaluate the leaching of con-


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8 SW-846 specifies several procedures that should be followed when analyzing oily wastes.

stituents from wastes. The SPLP was designedto estimate the leachability of both organicand inorganic analytes present in liquids, soils,and wastes. The SPLP was originally designedto assess how clean a soil was under EPA’sClean Closure Program. Even though the fed-eral hazardous waste program, did not adoptit for use, the test can still estimate releasesfrom wastes placed in a landfill and subject toacid rain. There might be, however, importantdifferences between soil as a constituentmatrix (for which the SPLP is primarily used)and the matrix of a generated industrial waste.A copy of Method 1312 has been included onthe CD-ROM version of the Guide.

The SPLP is very similar to the TCLPMethod 1311. Waste samples containingsolids and liquids are handled by separatingthe liquids from the solid phase, and thenreducing solids to particle size. The solids arethen extracted with a dilute sulfuricacid/nitric acid solution. A liquid-to-solidratio of 20:1 by weight is used for an extrac-tion period of 18±2 hours. After extraction,the solids are filtered from the liquid extractand the liquid extract is combined with anyoriginal liquid fraction of the wastes.Analyses are then conducted on the liquid fil-trate/leachate to determine the constituentconcentrations.

The sulfuric acid/nitric acid extractionsolution used in the SPLP was selected tosimulate leachate generation, in part, fromacid rain. Also note that in both the SPLP

and TCLP, some paint and oily wastes mightclog the filters used to separate the liquidextract from the solids prior to analysis,resulting in under reporting of the extractableconstituent concentrations.

3. Multiple Extraction Procedure(MEP)

The MEP (designated as EPA Method 1320in SW-846) was designed to simulate theleaching that a waste will undergo from repeti-tive precipitation of acid rain on a landfill todetermine the highest concentration of eachconstituent that is likely to leach in a realworld environment. Currently, the MEP is usedin EPA’s hazardous waste delisting program. Acopy of Method 1320 has been included onthe CD-ROM version of the Guide.

The MEP can be used to evaluate liquid,solid, and multiphase samples. Waste sam-ples are extracted according to the ExtractionProcedure (EP) Toxicity Test (Method 1310of SW-846). The EP test is also very similarto the TCLP Method 1311. A copy of Method1310 has been included on the CD- ROMversion of the Guide.

In the MEP, liquid wastes are filteredthrough a glass fiber filter prior to testing.Waste samples containing both solids and liq-uids are handled by separating the liquidsfrom the solid phase, and then reducing thesolids to particle size. The solids are thenextracted using an acetic acid solution. A liq-uid- to-solid ratio of 16:1 by weight is usedfor an extraction period of 24 hours. Afterextraction, the solids are filtered from the liq-uid extract, and the liquid extract is combinedwith any original liquid fraction of the waste.

The solids portion of the sample thatremains after application of Method 1310 arethen re-extracted using a dilute sulfuricacid/nitric acid solution. As in the SPLP, thisacidic solution was selected to simulate

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leachate generation, in part, from acid rain.This time a liquid-to-solid ratio of 20:1 byweight is used for an extraction period of 24hours. After extraction, the solids are onceagain filtered from the liquid extract, and theliquid extract is combined with any originalliquid fraction of the waste.

These four steps are repeated eight addi-tional times. If the concentration of any con-stituent of concern increases from the 7th or8th extraction to the 9th extraction, the pro-cedure is repeated until these concentrationsdecrease.

The MEP is intended to simulate 1,000years of freeze and thaw cycles and prolongedexposure to a leaching medium. One advan-tage of the MEP over the TCLP is that theMEP gradually removes excess alkalinity inthe waste. Thus, the leaching behavior ofmetal contaminants can be evaluated as afunction of decreasing pH, which increasesthe solubility of most metals.

4. Shake Extraction of SolidWaste with Water or NeutralLeaching Procedure

The Shake Extraction of Solid Waste withWater, or the Neutral Leaching Procedure,was developed by the American Society forTesting and Materials (ASTM) to assess theleaching potential of solid waste and has beendesignated as ASTM D-3987-85. This testmethod provides for the shaking of an extrac-tant (e.g., water) and a known weight ofwaste of specified composition to obtain anaqueous phase for analysis after separation.The intent of this test method is for the finalpH of the extract to reflect the interaction ofthe liquid extractant with the buffering capac-ity of the solid waste.

The shake test is performed by mixing thesolid sample with test water and agitatingcontinuously for 18±0.25 hours. A liquid-to-

solid ratio of 20:1 by weight is used. Afteragitation the solids are filtered from the liquidextract, and the liquid is analyzed.

The water extraction is meant to simulateconditions where the solid waste is the domi-nant factor in determining the pH of theextract. This test, however, has only beenapproved for certain inorganic constituents,and is not applicable to organic substancesand volatile organic compounds (VOCs). Acopy of this procedure can be ordered bycalling ASTM at 610 832-9585 or online at<www.astm.org>.

III. WasteCharacterizationof VolatileOrganicEmissions

To determine whether volatile organicemissions are of concern at a waste manage-ment unit, determine the concentration of theVOCs that are reasonably expected to beemitted. Process knowledge is likely to beless accurate for determining VOCs thanmeasured values. As discussed earlier in thischapter, modeling results for waste manage-ment units will only be as accurate as theinput data. Therefore, sampling and analyticaltesting might be necessary if organic concen-trations cannot be estimated confidentlyusing process knowledge.

Table 2 in Chapter 5–Protecting Air Qualitycan be used as a starting point to help youdetermine which air emissions constituents tomeasure. It is not recommended that yousample for all of the volatile organics listed inTable 2, but rather use Table 2 as a guide inconjunction with process knowledge to nar-row the sampling effort and thereby minimize


2-13

unnecessary sampling costs. A thoroughunderstanding of process knowledge can helpyou determine what is reasonably expected tobe in the waste, so that it is not necessary tosample for unspecified constituents.

Many tests have been developed for quan-titatively extracting volatile and semi-volatileorganic constituents from various samplematrices. These tests tend to be highlydependent upon the physical characteristicsof the sample. You should consult with stateand local regulatory agencies before imple-menting testing. You can refer to SW-846Method 3500B for guidance on the selectionof methods for quantitative extraction ordilution of samples for analysis by one of thevolatile or semi-volatile determinative meth-ods. After performing the appropriate extrac-tion procedure, further cleanup of the sampleextract might be necessary if analysis of theextract is prevented due to interferencescoextracted from the sample. Method 3600of SW-846 provides additional guidance oncleanup procedures.

Following sample preparation, a sample isready for further analysis. Most analyticalmethods use either gas chromatography(GC), high performance liquid chromatogra-phy (HPLC), gas chromatography/mass spec-trometry (GC/MS), or high performanceliquid chromatography/mass spectrometry(HPLC/MS). SW-846 is designed to allow themethods to be mixed and matched, so thatsample preparation, sample cleanup, andanalytical methods can be properlysequenced for the particular analyte andmatrix. Again, you should consult with stateand local regulatory agencies before finalizingthe selected methodology.

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2-15

To determine constituent concentrations in a waste you should:

■■■■ Assess the physical state of the waste using process knowledge.

■■■■ Use process knowledge to identify constituents for further analysis.

■■■■ Assess the environment in which the waste will be placed.

■■■■ Consult with state and local regulatory agencies to determine any specific testing requirements.

■■■■ Select an appropriate leachate test or organic constituent analysis based on the above information.

Waste Characterization Activity List

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ASTM. 1995. Annual Book of ASTM Standards.

ASTM. Standard Methods for Examination of Water and Wastewater.

ASTM. D-3987-85. Standard Test Method for Shake Extraction of Solid Waste with Water

California EPA. Handbook for the Analysis and Classification of Wastes.

California EPA. 1995. Preliminary Proposal to Require the TCLP in Lieu of the Waste ExtractionTest. Memorandum to James Carlisle, Department of Toxics Substances Control, from JonMarshack, California Regional Water Quality Control Board. December 18.

California EPA. 1994. Regulation Guidance: When Extraction Tests are Not Necessary.

California EPA. 1994. Regulation Guidance: TCLP vs. WET.

California EPA. 1993. Regulation Guidance: Lab Methods.

California EPA. 1993. Regulation Guidance: Self-Classification.

Cochran, W.G. 1977. Sampling Techniques. Third Edition. New York: John Wiley and Sons.

Dusing, D.C., Bishop, P.L., and Keener, T.C. 1992. Effect of Redox Potential on Leaching fromStabilized/Solidified Waste Materials. Journal of Air and Waste Management Association. 42:56.January.

Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. New York: VanNostrand Reinhold Company.

Kendall, Douglas. 1996. Impermanence of Iron Treatment of Lead-Contaminated Foundry Sand—NIBCO, Inc., Nacogdoches, Texas. National Enforcement Investigations Center Project PA9. April.

Kosson, D.S., H.A. van der Sloot, F. Sanchez, and A.C. Garrabrants. 2002. An IntegratedFramework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials.Environmental Engineering Science, In-press.

New Jersey Department of Environmental Protection. 1996. Industrial Pollution Prevention Trendsin New Jersey.

Resources


2-17

Northwestern University. 1995. Chapter 4—Evaluation of Procedures for Analysis and Disposal ofLead- Based Paint-Removal Debris. Issues Impacting Bridge Painting: An Overview. InfrastructureTechnology Institute. FHWA/RD/94/098. August.

U.S. EPA 2002. Industrial Waste Managment Evaluation (IWEM) Technical Background Document.EPA530-R-02-012.

U.S. EPA. 1998a. Guidance on Quality Assurance Project Plans: EPA QA/G-5. EPA600-R-98-018.

U.S. EPA. 1998b. Guidance on Sampling Designs to Support QA Project Plans. QA/G-5S

U.S. EPA. 1997. Extraction Tests. Draft.

U.S. EPA. 1996a. Guidance for the Data Quality Assessment: Practical Methods for Data Analysis:EPAQA/G-9. EPA600-R-96-084.

U.S. EPA. 1996b. Guidance for the Data Quality Objectives Process: EPA QA/G-4. EPA600-R-96-055.

U.S. EPA. 1996c. Hazardous Waste Characteristics Scoping Study.

U.S. EPA. 1996d. National Exposure Research Laboratory (NERL)-Las Vegas: Site CharacterizationLibrary, Volume 2.

U.S. EPA. 1996e. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. ThirdEdition.

U.S. EPA. 1995. State Requirements for Non-Hazardous Industrial Waste Management Facilities.

U.S. EPA. 1993. Identifying Higher-Risk Wastestreams in the Industrial D Universe: The StateExperience. Draft.

U.S. EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-088.

U.S. EPA Science Advisory Board. 1991. Leachability Phenomena: Recommendations and Rationale forAnalysis of Contaminant Release by the Environmental Engineering Committee. EPA-SAB-EEC-92-003.

Winer, B.J. 1971. Statistical Principles in Experimental Design. New York: McGraw-Hill.

Resources (cont.)

Test Method Leaching Fluid Liquid:Solid Maximum Number of Time of CommentsRatio Particle Size Extractions Extractions

I. Static Tests

A. Agitated Extraction Tests

Toxicity 0.1 N acetic acid solution, 20:1 9.5 mm 1 18 ±2 hours Co-disposal scenario might Characteristic pH 2.9, for alkaline wastes not be appropriate; no Leaching 0.1 N sodium acetate allowance for structural Procedure (1311) buffer solution, pH 5.0, integrity testing of

for non-alkaline wastes monolithic samples

Extraction 0.5 N acetic acid (pH-5.0) 16:1 during 9.5 mm 1 24 hours High alkalinity samples can Procedure extraction result in variable dataToxicity Test (1310) 20:1 final

dilution

ASTM D3987-85 ASTM IV reagent water 20:1 As in 1 18 hours Not validated for organicsShake Extraction environment of Solid Waste (as received)with Water

California WET 0.2 M sodium citrate 10:1 2.0 mm 1 48 hours Similar to EP, but sodium(pH- 5.0) citrate makes test more

aggressive

Ultrasonic Distilled water 4:1 Ground 1 30 minutes New—little performance Agitation dataMethod for Accelerating Batch Leaching Test9

Alternative TCLP TCLP acetic acid solutions 20:1 <9.5 1 8 hours Uses heat to decrease for Construction, extraction timeDemolition and Lead Paint Abatement Debris10

Extraction Soxhlet with THF and 100g:300mL 9.5 mm 3 24 hours (EP)Procedure for Oily toluene EP on remaining 20:1Waste (1330) solids

Synthetic #1 Reagent water to pH 4.2 20:1 9.5 mm 1 18±2 hours ZHE option for organicsPrecipitation with nitric and sulfuric Leaching Procedure acids (60/40) (1312) #2 Regent water to pH 5.0

with nitric and sulfuric acids (60/40)

Equilibrium Leach Distilled water 4:1 150 mm 1 7 days Determines contaminants Test that have been insolubilized

by solidification

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9 Bisson, D.L.; Jackson D.R.; Williams K.R.; and Grube W.E. J. Air Waste Manage. Assoc., 41: 1348-1354.

10 Olcrest, R. A Representative Sampling and Alternative Analytical Toxic Characteristic Leachate ProcedureMethod for Construction, Demolition, and Lead Paint Abatement Debris Suspected of Containing LeachableLead, Appl. Occup. Environ. Hyg. 11(1), January 1996.

Appendix: Example Extraction Tests (Draft 9/30/97)

B. Non-Agitated Extraction Tests

Static Leach Test Can be site specific, 3 VOL/surface 40 mm2 1 >7 days Series of optional steps Method (material standard leachates: water, 10 cm surface area increasing complexity of characteristic brine, silicate/bicarbonate analysiscentre- 1)

High Temperature Same as MCC-1 (conducted VOL/Surface 40 mm2 1 >7 Days Series of optional steps Static Leach Tests at 100°C) 10 cm Surface Area increasing complexity of Method (material analysischaracterization centre-2)

C. Sequential Chemical Extraction Tests

Sequential 0.04 m acetic acid 50:1 9.5 mm 15 24 hours per Extraction Tests extraction

D. Concentration Build-Up Test

Sequential 5 leaching solutions of Varies from 150 mm 5 Varies 3 or Examines partitioning of Chemical increasing acidity 16.1 to 40.1 14 days metals into different Extraction fractions or chemicals forms

Standard Leach DI water SYN Landfill 10:1, 5:1, As in 3 3 or 14 days Sample discarded after each Test, Procedure C 7.5:1 environment leach, new sample added to (Wisconsin) existing leachate

II. Dynamic Tests (Leaching Fluid Renewed)

A. Serial Batch (Particle)

Multiple Extraction Same as EP TOX, then 20:1 9.5 mm 9 (or more) 24 hours perProcedure (1320) with synthetic acid rain extraction

(sulfuric acid, nitric acid in 60:40% mixture)

Monofill Waste Distilled/deionized water 10:1 per 9.5 mm or 4 18 hours perExtraction or other for specific site extraction monolith extractionProcedures

Graded Serial Batch Distilled water Increases N/A >7 Until steady (U.S. Army) from 2:1 to state

96:1

Sequential Batch Type IV reagent water 20:1 As in 10 18 hoursExt. of Waste with environmentWater ASTM D-4793-93


2-19


Use of Chelating Demineralized water with 50 or 100 <300 µm 1 18, 24, or Experimental test based on Agent to Determine EDTA, sample to a final 48 hours Method 7341the Metal pH of 7±0.5Availability for Leaching Soils and Wastes11

B. Flow Around Tests

IAEA Dynamic DI water/site water N/A One face >19 >6 monthsLeach Test prepared(International Atomic Energy Agency)

Leaching Tests on 0.1N acetic acid 20:1 0.6 µm-70µm 1 24 hours S/S technologies most valid Solidified Products12 (Procedure A) when applied to wastes

2:1 (6 hrs.) contaminated by inorganic & 10:1 pollutants(18 hrs.) (Procedure B)

DLT DI water N/A Surface 18 196 dayswashing

C. Flow Through Tests

ASTM D4874-95 Type IV reagent water One void 10 mm 1 24 hoursColumn Test volume

III. Other Tests

MCC-5s Soxhlet DI/site water 100:1 Out and 1 0.2 ml/minTest (material washedcharacteristic center)

ASTM C1308-95 Only applicable if diffusion Accelerated Leach is dominant leaching Test13 mechanism

Generalized Acid Acetic acid 20:1 Able to pass 1 48 hours Quantifies the alkalinity of Neutralization through an binder and characterizes Capacity Test14 ASTM No. 40 buffering chemistry

sieve

Acid Neutralization HNO3, solutions of 3:1 150 mm 1 48 hours per Capacity increasing strength extraction

2-20

11 Garrabrants, A.C. and Koson, D.S.; Use of Chelating Agent to Determine the Metal Availability for Leachingfrom Soils and Wastes, unpublished.

12 Leaching Tests on Solidified Products; Gavasci, R., Lombardi, F., Polettine, A., and Sirini, P.

13 C1308-95 Accelerated Leach Test for Diffusive Releases from Solidified Waste and a Computer Program toModel Diffusive, Fractional Leaching from Cylindrical Wastes.

14 Generalized Acid Neutralization capacity Test; Isenburg, J. and Moore, M.




Chapter 3Integrating Pollution Prevention

Contents

I. Benefits of Pollution Prevention..................................................................................................................3 - 3

II. Implementing Pollution Prevention ........................................................................................................3 - 5

A. Source Reduction ..................................................................................................................................3 - 5

B. Recycling ..............................................................................................................................................3 - 7

C. Treatment ..............................................................................................................................................3 - 8

III. Where to Find Out More: Technical and Financial Assistance ..............................................................3 - 10

Integrating Pollution Prevention Activity List ..............................................................................................3 - 14

Resources ....................................................................................................................................................3 - 15

Figure 1: Waste Management Hierarchy........................................................................................................3 - 2

Getting Started—Integrating Pollution Prevention

3-1

Pollution prevention describes a vari-ety of practices that go beyond tra-ditional environmental complianceor single media permits for water,air, or land disposal and begin to

address the concept of sustainability in theuse and reuse of natural resources. Adoptingpollution prevention policies and integratingpollution prevention into operations provideopportunities to reduce the volume and toxic-ity of wastes, reduce waste disposal needs,and recycle and reuse materials formerly han-dled as wastes. In addition to potential sav-ings on waste management costs, pollutionprevention can help improve the interactions

among industry, the public, and regulatoryagencies. It can also reduce liabilities and risksassociated with releases from waste manage-ment units and closure and post-closure careof waste management units.

Pollution prevention is comprehensive.It emphasizes a life-cycle approach to assess-ing a facility’s physical plant, productionprocesses, and products to identify the bestopportunities to minimize environmentalimpacts across all media. This approach alsoensures that actions taken in one area will notincrease environmental problems in anotherarea, such as reducing wastewater dischargesbut increasing airborne emissions of volatileorganic compounds. Pollution preventionrequires creative problem solving by a broadcross section of employees to help achieveenvironmental goals. In addition to the envi-ronmental benefits, implementing pollutionprevention can often benefit a company inmany other ways. For example, redesigningproduction processes or finding alternativematerial inputs can also improve productquality, increase efficiency, and conserve rawmaterials. Some common examples of pollu-tion prevention activities include: redesigning

Integrating Pollution Prevention

This chapter will help you:

• Consider pollution prevention options when designing a waste

management system. Pollution prevention will reduce waste dis-

posal needs and can minimize impacts across all environmental

media. Pollution prevention can also reduce the volume and toxi-

city of waste. Lastly, pollution prevention can ease some of the

burdens, risks, and liabilities of waste management.

This chapter will help address the fol-lowing questions.

• What are some of the benefits of pol-lution prevention?

• Where can assistance in identifyingand implementing specific pollutionprevention options be obtained?

3-2

Getting Started—Intregrating Pollution Prevention

processes or products to reduce raw materialneeds and the volume of waste generated;replacing solvent based cleaners with aqueousbased cleaners or mechanical cleaning sys-tems; and instituting a reverse distributionsystem where shipping packaging is returnedto the supplier for reuse rather than discard.

The Pollution Prevention Act of 1990established a national policy to first, preventor reduce waste at the point of generation(source reduction); second, recycle or reusewaste materials; third, treat waste; and finally,dispose of remaining waste in an environ-mentally protective manner (see Figure 1).Some states and many local governmentshave adopted similar policies, often withmore specific and measurable goals.

Source Reduction means any practicewhich (i) reduces the amount of any sub-stance, pollutant, or contaminant enteringany wastestream or otherwise released intothe environment, prior to recycling, treat-ment, or disposal; and (ii) reduces the risksto public health and the environment associ-

ated with the release of such substances, pol-lutants, or contaminants.

Recycling requires an examination ofwaste streams and production processes toidentify opportunities. Recycling and benefi-cially reusing wastes can help reduce disposalcosts, while using or reusing recycled materi-als as substitutes for feedstocks can reduceraw materials costs. Materials exchange pro-grams can assist in finding uses for recycledmaterials and in identifying effective substi-tutes for raw materials. Recycling not onlyhelps reduce the overall amount of waste sentfor disposal, but also helps conserve naturalresources by replacing the need for virginmaterials.

Treatment can reduce the volume andtoxicity of a waste. Reducing a waste’s volumeand toxicity prior to final disposal can resultin long-term cost savings. There are a consid-erable number of levels and types of treat-ment from which to choose. Selecting theright treatment option can help simplify dis-posal options and limit future liability.

Figure 1. Waste Management Hierarchy


3-3

Over the past 10 years, interest in all aspectsof pollution prevention has blossomed, andgovernments, businesses, academic andresearch institutions, and individual citizenshave dedicated greater resources to it. Manyindustries are adapting pollution preventionpractices to fit their individual operations.Pollution prevention can be successful whenflexible problem-solving approaches and solu-tions are implemented. Fitting these steps intoyour operation’s business and environmentalgoals will help ensure your program’s success.

Throughout the Guide several key steps arehighlighted that are ideal points for imple-menting pollution prevention to help reducewaste management costs, increase options, orreduce potential liabilities by reducing risksthat the wastes might pose. For example:

Waste characterization is a key compo-nent of the Guide. It is also a key componentof a pollution prevention opportunity assess-ment. An opportunity assessment, however, ismore comprehensive since it also covers mate-rial inputs, production processes, operatingpractices, and potentially other areas such asinventory control. When characterizing awaste, consider expanding the opportunityassessment to cover these aspects of the busi-ness. An opportunity assessment can helpidentify the most efficient, cost-effective, andenvironmentally friendly combination ofoptions, especially when planning new prod-ucts, new or changed waste management prac-tices, or facility expansions.

Land application of waste might be a pre-ferred waste management option because landapplication units can manage wastes with highliquid content, treat wastes through biodegra-dation, and improve soils due to the organicmaterial in the waste. Concentrations of con-stituents might limit the ability to take fulladvantage of land application. Reducing theconcentrations of constituents in the wastebefore it is generated or treating the waste prior

to land application can provide the flexibility touse land application and ensure that the prac-tice will be protective of human health and theenvironment and limit future liabilities.

I. Benefits ofPollutionPrevention

Pollution prevention activities benefitindustry, states, and the public by protectingthe environment and reducing health risks,and also provide businesses with financial andstrategic benefits.

Protecting human health and the envi-ronment. By reducing the amount of contami-nants released into the environment and thevolume of waste requiring disposal, pollutionprevention activities protect human health andthe environment. Decreasing the volume ortoxicity of process materials and wastes canreduce worker exposure to potentially harmfulconstituents. Preventing the release and dis-posal of waste constituents to the environmentalso reduces human and wildlife exposure andhabitat degradation. Reduced consumption ofraw materials and energy conserves preciousnatural resources. Finally reducing the volumeof waste generated decreases the need for con-struction of new waste management facilities,preserving land for other uses such as recre-ation or wildlife habitat.

Cost savings. Many pollution preventionactivities make industrial processes and equip-ment more resource-efficient. This increasedproduction efficiency saves raw material andlabor costs, lowers maintenance costs due tonewer equipment, and potentially lowers over-sight costs due to process simplification. Whenplanning pollution prevention activities, con-sider the cost of the initial investment foraudits, equipment, and labor. This cost will

3-4


vary depending onthe size and com-plexity of wastereduction activi-ties. In addition,consider the pay-back time for theinvestment.Prioritize pollutionprevention activi-ties to maximizecost savings andhealth and envi-ronmental benefits.

Simpler design and operating conditions.Reducing the risks associated with wastes canallow wastes to be managed under less strin-gent design and operating conditions. Forexample, the ground-water tool in Chapter 7,Section A – Assessing Risk might indicate thata composite liner is recommended for a specif-ic waste stream. A pollution prevention oppor-tunity assessment also might imply that byimplementing a pollution prevention activitythat lowers the concentrations of one or twoproblematic waste constituents in that wastestream, a compacted clay liner can providesufficient protection. When the risks associat-ed with waste disposal are reduced, the long-term costs of closure and post-closure care canalso be reduced.

Improved work-er safety. Processesinvolving less toxicand less physicallydangerous materialscan improve workersafety by reducingwork-related injuriesand illnesses. Inaddition to strength-ening morale,improved workersafety also reduces

health-related costs from lost work days,health insurance, and disability payments.

Lower liability. A well-operated unit mini-mizes releases, accidents, and unsafe waste-handling practices. Reducing the volume andtoxicity of waste decreases the impact of theseevents if they occur. Reducing potential liabili-ties decreases the likelihood of litigation andcleanup costs.

Higher product quality. Many corporationshave found that higher product quality resultsfrom some pollution prevention efforts. A sig-nificant part of the waste in some operationsconsists of products that fail quality inspec-tions, so minimizing waste in those cases isinextricably linked with process changes thatimprove quality. Often, managers do not realizehow easy or technically feasible such changesare until the drive for waste reduction leads toexploration of the possibilities.

Building community relations. Honestyand openness can strengthen credibilitybetween industries, communities, and regula-tory agencies. If you are implementing a pollu-tion prevention program, make people awareof it. Environmental protection and economicgrowth can be compatible objectives.Additionally, dialogue among all parties in thedevelopment of pollution prevention plans canhelp identify and address concerns.

3-5


II. ImplementingPollutionPrevention

When implementing pollution prevention,consider a combination of options that bestfits your facility and its products. There are anumber of steps common to implementingany facility-wide pollution prevention effort.An essential starting point is to make a clearcommitment to identifying and taking advan-tage of pollution prevention opportunities.Seek the participation of interested partners,develop a policy statement committing theindustrial operation to pollution prevention,and organize a team to take responsibility forit. As a next step, conduct a thorough pollu-tion prevention opportunity assessment. Suchan assessment will help set priorities accord-ing to which options are the most promising.Another feature common to many pollutionprevention programs is measuring the pro-gram’s progress.

The actual pollution prevention practicesimplemented are the core of a program. Thefollowing sections give a brief overview ofthese core activities: source reduction, recy-cling, and treatment. To find out more, con-tact some of the organizations listedthroughout this chapter.

A. Source ReductionAs defined in the Pollution Prevention Act

of 1990, source reduction means any practicewhich (i) reduces the amount of any haz-ardous substance, pollutant, or contaminantentering any wastestream or otherwisereleased into the environment, prior to recy-cling, treatment, or disposal; and (ii) reducesthe hazards to public health and the environ-ment associated with the release of such sub-stances, pollutants, or contaminants. Theterm includes equipment or technology mod-

ifications; process or procedure modifica-tions; reformulations or redesign of products;substitution of raw materials; and improve-ments in housekeeping, maintenance, train-ing, or inventory control.

Reformulationor redesign ofproducts. Onesource reductionoption is to refor-mulate or redesignproducts andprocesses to incor-porate materialsmore likely to pro-duce lower-riskwastes. Some of themost commonpractices include eliminating metals frominks, dyes, and paints; reformulating paints,inks, and adhesives to eliminate syntheticorganic solvents; and replacing chemical-based cleaning solvents with water-based orcitrus-based products. Using raw materialsfree from even trace quantities of contami-nants, whenever possible, can also helpreduce waste at the source.

When substituting materials in an industri-al process, it is important to examine theeffect on the entire waste stream to ensurethat the overall risk is being reduced. Somechanges can shift contaminants to anothermedium rather than actually reduce wastegeneration. Switching from solvent-based towater-based cleaners, for example, willreduce solvent volume and disposal cost, butis likely to dramatically increase wastewatervolume. Look at the impact of wastewatergeneration on effluent limits and wastewatertreatment sludge production.

Technological modifications. Newerprocess technologies often include betterwaste reduction features than older ones. Forindustrial processes that predate considera-

3-6


tion of waste and risk reduction, adoptingnew procedures or upgrading equipment canreduce waste volume, toxicity, and manage-ment costs. Some examples include redesign-ing equipment to cut losses during batchchanges or during cleaning and maintenance,changing to mechanical cleaning devices toavoid solvent use, and installing more energy-and material-efficient equipment. State tech-nical assistance centers, trade associations,and other organizations listed in this chaptercan help evaluate the potential advantagesand savings of such improvements.

In-process recycling (reuse). In-processrecycling involves the reuse of materials, suchas cutting scraps, as inputs to the sameprocess from which they came, or uses themin other processes or for other uses in thefacility. This furthers waste reduction goals byreducing the need for treatment or disposaland by conserving energy and resources. Acommon example of in-process recycling isthe reuse of wastewater.

Good housekeeping procedures. Some ofthe easiest, most cost-effective, and most wide-ly used waste reduction techniques are simpleimprovements in housekeeping. Accidents andspills generate avoidable disposal hazards andexpenses. They are less likely to occur inclean, neatly organized facilities.

Good housekeeping techniques that reducethe likelihood of accidents and spills includetraining employees to manage waste andmaterials properly; keeping aisles wide andfree of obstructions; clearly labeling contain-ers with content, handling, storage, expira-tion, and health and safety information;spacing stored materials to allow easy access;surrounding storage areas with containmentberms to control leaks or spills; and segregat-ing stored materials to avoid cross-contami-nation, mixing of incompatible materials, andunwanted reactions. Proper employee train-ing is crucial to implementing a successful

waste reduction program, especially one fea-turing good housekeeping procedures. Casestudy data indicate that effective employeetraining programs can reduce waste disposalvolumes by 10 to 40 percent.1

Regularly scheduled maintenance andplant inspections are also useful. Maintenancehelps avoid the large cleanups and disposaloperations that can result from equipmentfailure. Routine maintenance also ensures thatequipment is operating at peak efficiency, sav-ing energy, time, and materials. Regularlyscheduled or random, unscheduled plantinspections help identify potential problemsbefore they cause waste management prob-lems. They also help identify areas whereimproving the efficiency of materials manage-ment and handling practices is possible. Ifpossible, plant inspections, periodically per-formed by outside inspectors who are lessfamiliar with day-to-day plant operations, canbring attention to areas for improvement thatare overlooked by employees accustomed tothe plant’s routine practices.

Storing large volumes of raw materialsincreases the risk of an accidental spill andthe likelihood that the materials will not beused due to changes in production schedules,new product formulations, or material degra-dation. Companies are sometimes forced todispose of materials whose expiration dateshave passed or that are no longer needed.Efficient inventory control allows a facility toavoid stocking materials in excess of its abili-ty to use them, thereby decreasing disposalvolume and cost. Many companies have suc-cessfully implemented “just-in-time” manu-facturing systems to avoid the costs and risksassociated with maintaining a large onsiteinventory. In a “just-in-time” manufacturingsystem, raw materials arrive as they are need-ed and only minimal inventories are main-tained on site.

1 Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc. p. 13.


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Segregating waste streams is another goodhousekeeping procedure that enables a facili-ty to avoid contaminating lower risk wasteswith hazardous constituents from anothersource. Based on a waste characterizationstudy, it might be more efficient and cost-effective to manage wastes separately by recy-cling some, and treating or disposing ofothers. Waste segregation can also helpreduce the risks associated with handlingwaste. Separating waste streams allows somematerials to be reused, resulting in additionalcost savings. Emerging markets for recoveredindustrial waste materials are creating neweconomic incentives to segregate wastestreams. Recovered materials are more attrac-tive to potential buyers if it can be ensuredthat they are not tainted with other wastematerials. For example, if wastes from metal-finishing facilities are segregated by type,metal-specific-bearing sludge can be recov-ered more economically and the segregatedsolvents and waste oils can be recycled.

B. RecyclingRecycling involves col-

lecting, processing, andreusing materials thatwould otherwise be han-dled as wastes. The fol-lowing discussion highlights a few of theways to begin this process.

Materials exchange programs. Many localgovernments and states have established mate-rials exchange programs to facilitate transac-tions between waste generators and industriesthat can use wastes as raw materials. Materialsexchanges are an effective and inexpensive wayto find new users and uses for a waste. Mostare publicly funded, nonprofit organizations,although some charge a nominal fee to be list-ed with them or to access their online databas-es. Some actively work to promote exchangesbetween generators and users, while others

simply publish lists of generators, materials,and buyers. Some waste exchanges also spon-sor workshops and conferences to discusswaste-related regulations and to exchangeinformation. More than 60 waste and materialsexchanges operate in North America. Beloware four examples of national, state, and localexchange programs. Each program’s Web sitealso provides links to other regional, national,and international materials exchange net-works.

• EPA’s Jobs Through Recycling (JTR)Web site <www.epa.gov/jtr/comm/exchange.htm> provides descriptionsof and links to international, national,and state-specific materials exchangeprograms and organizations.

• Recycler’s World <www.recycle.net/exch/index.html> is a world-widematerials trading site with links todozens of state and regional exchangenetworks.

• CalMAX (California MaterialsExchange) <www.ciwmb.ca.gov/calmax> is maintained by theCalifornia Integrated WasteManagement Board and facilitateswaste exchanges in California andprovides links to other local andnational exchange programs.

• King County, Washington’s IMEX<www.metrokc.gov/hazwaste/imex/exchanges.html/> is a local industri-al materials exchange program thatalso provides an extensive list ofstate, regional, national, and interna-tional exchange programs.

Beneficial use. Beneficial use involvessubstituting a waste material for anothermaterial with similar properties. Utility com-panies, for example, often use coal combus-tion ash as a construction material, road base,or soil stabilizer. The ash replaces other, non-

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recycled materials, such as fill or Portlandcement, not only avoiding disposal costs butalso generating revenue. Other examples ofbeneficial use include using wastewaters andsludges as soil amendments (see Chapter 7,Section C–Designing a Land ApplicationProgram) and using foundry sand in asphalt,concrete, and roadbed construction.

Many regulatory agencies require approvalof planned beneficial use activities and mayrequire testing of the materials to be reused.Others may allow certain wastes to be desig-nated for beneficial use, as long as the requiredanalyses are completed. Pennsylvania, forexample, allows application of a “coproduct”designation to, and exemption from waste reg-ulations for “materials which are essentiallyequivalent to and used in place of an inten-tionally manufactured product or producedraw material and... [which present] no greaterrisk to the public or the environment.”Generally, regulatory agencies want to ensurethat any beneficially used materials are freefrom significantly increased levels of con-stituents that might pose a greater risk thanthe materials they are replacing. Consult withthe state agency for criteria and regulationsgoverning beneficial use.

In a continuing effort to promote the use ofmaterials recovered from solid waste, theEnvironmental Protection Agency (EPA) hasinstituted the Comprehensive ProcurementGuideline (CPG) program. Using recycled-con-tent products ensures that materials collectedin recycling programs will be used again in themanufacture of new products. The CPG pro-gram is authorized by Congress under Section6002 of the Resource Conservation andRecovery Act (RCRA) and Executive Order13101. Under the CPG program, EPA isrequired to designate products that are or canbe made with recovered materials and to rec-ommend practices for buying these products.Once a product is designated, procuring agen-cies are required to purchase it with the high-

est recovered material content level practica-ble. As of January 2001, EPA has designated54 items within eight product categoriesincluding items such as retread tires, cementand concrete containing coal fly ash andground granulated blast furnace slag, trafficbarricades, playground surfaces, landscapingproducts, and nonpaper office products likebinders and toner cartridges. While directedprimarily at federal, state, and local procuringagencies, CPG information is helpful to every-one interested in purchasing recycled-contentproducts. For further information on the CPGprogram, visit: <www.epa.gov/cpg>.

C. TreatmentTreatment of non-hazardous industrial

waste is not a federal requirement, however,it can help to reduce the volume and toxicityof waste prior to disposal. Treatment can alsomake a waste amenable for reuse or recycling.Consequently, a facility managing non-haz-ardous industrial waste might elect to applytreatment. For example, treatment might beincorporated to address volatile organic com-pound (VOC) emissions from a waste manag-ment unit, or a facility might elect to treat awaste so that a less stringent waste manage-ment system design could be used. Treatmentinvolves changing a waste’s physical, chemi-cal, or biological character or compositionthrough designed techniques or processes.There are three primary categories of treat-ment—physical, chemical, and biological.

Physical treatment involves changing thewaste’s physical properties such as its size,shape, density, or state (i.e., gas, liquid, solid).Physical treatment does not change a waste’schemical composition. One form of physicaltreatment, immobilization, involves encapsu-lating waste in other materials, such as plastic,resin, or cement, to prevent constituents fromvolatilizing or leaching. Listed below are a fewexamples of physical treatment.


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• Immobilization:EncapsulationThermoplastic binding

• Carbon absorption:Granular activated carbon (GAC)Powdered activated carbon (PAC)

• Distillation:Batch distillationFractionationThin film extractionSteam strippingThermal drying

• Filtration

• Evaporation/volatilization

• Grinding

• Shredding

• Compacting

• Solidification/addition of absorbentmaterial

Chemical treatment involves altering awaste’s chemical composition, structure, andproperties through chemical reactions.Chemical treatment can consist of mixing thewaste with other materials (reagents), heatingthe waste to high temperatures, or a combi-nation of both. Through chemical treatment,waste constituents can be recovered ordestroyed. Listed below are a few examples ofchemical treatment.

• Neutralization

• Oxidation

• Reduction

• Precipitation

• Acid leaching

• Ion exchange

• Incineration

• Thermal desorption

• Stabilization

• Vitrification

• Extraction:Solvent extractionCritical extraction

• High temperature metal recovery(HTMR)

Biological treatment can be divided into twocategories–aerobic and anaerobic. Aerobic bio-logical treatment uses oxygen-requiringmicroorganisms to decompose organic andnon-metallic constituents into carbon dioxide,water, nitrates, sulfates, simpler organic prod-ucts, and cellular biomass (i.e., cellular growthand reproduction). Anaerobic biological treat-ment uses microorganisms, in the absence ofoxygen, to transform organic constituents andnitrogen-containing compounds into oxygenand methane gas (CH4(g)). Anaerobic biologi-cal treatment typically is performed in anenclosed digestor unit. Listed below are a fewexamples of biological treatment.

• Aerobic:Activated sludgeAerated lagoonTrickling filterRotating biological contactor (RBC)

• Anaerobic digestion

The range of treatment methods fromwhich to choose is as diverse as the range ofwastes to be treated. More advanced treat-ment will generally be more expensive, butby reducing the quantity and risk level of thewaste, costs might be reduced in the longrun. Savings could come from not only lowerdisposal costs, but also lower closure andpost-closure care costs. Treatment and post-treatment waste management methods can beselected to minimize both total cost and envi-ronmental impact, keeping in mind that treat-ment residuals, such as sludges, are wastesthemselves that will need to be managed.

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III. Where to FindOut More:Technical andFinancialAssistance

There is a wealth of information available tohelp integrate pollution prevention into anoperation. As a starting point, a list of refer-ences to technical and financial resources isincluded in this section. The Internet can bean excellent source of background informationon the various resources to help begin thesearch for assistance. Waste reduction informa-tion and technologies are constantly changing.To follow new developments you should main-tain technical and financial contacts and con-tinue to use these resources even afterbeginning waste reduction activities. Eventual-ly, you can build a network of contacts to sup-port all your various technical needs.

Where Can Assistance Be

Obtained?

Several types of organizations offer assis-tance. These include offices in regulatoryagencies, university departments, nonprofitfoundations, and trade associations.Additionally, the National Institute ofStandards and Technology (NIST) Manu-facturing Extension Partnerships (MEPs)

<www.mep.nist.gov> also provide wastereduction information. Look for waste reduc-tion staff within the media programs (air,water, solid/hazardous waste) of regulatoryagencies or in the state commissioner’s office,special projects division, or pollution preven-tion division. Some states also provide techni-cal assistance for waste reduction activities,such as recycling, through a business advo-cate or small business technical assistanceprogram. EPA’s U.S. State & Local GatewayWeb site <www.epa.gov/epapages/statelocal/envrolst.htm> is a helpful tool forlocating your state environmental agency.

The listings below identify some primarysources for technical assistance that mightprove helpful. This list serves as a startingpoint only and is by no means exhaustive.There are many additional organizations thatoffer pollution prevention assistance onregional, state, and local levels.

• American Forest and PaperAssociation (AF&PA) is the nation-al trade association of the forest,paper, and wood products industries.It offers documents that might helpyou find buyers for wood and paperwastes. <www.afandpa.org> Phone:800 878-8878 e-mail: [email protected]

• California Integrated WasteManagement Board. This Web sitecontains general waste preventionbackground and business wastereduction program overviews, factsheets, and information about marketdevelopment for recycled materialsand waste reduction training.<www.ciwmb.ca.gov/WPW>

• Center for Environmental ResearchInformation (CERI) provides techni-cal guides and manuals on wastereduction, summaries of pollutionprevention opportunity assessments,

and waste reduction alternatives forspecific industry sectors.<www.epa.gov/ttbnrmrl/ttmat.htm>Phone: 513-569-7562 e-mail:[email protected]

• Enviro$en$e, part of the U.S. EPA’sWeb site, provides a single repositoryfor pollution prevention, complianceassurance, and enforcement informa-tion and data bases. Its search enginesearches multiple Web sites (insideand outside the EPA), and offersassistance in preparing a search.<es.epa.gov>

• National Pollution PreventionRoundtable (NPPR) promotes thedevelopment, implementation, andevaluation of pollution prevention.NPPR’s Web site provides an abridgedonline version of The PollutionPrevention Yellow Pages <www.p2.org/inforesources/nppr_yps.html>,a listing of local, state, regional andnational organizations, includingstate and local government programs,federal agencies, EPA pollution pre-vention coordinators, and non-profitgroups that work on pollution pre-vention. <www.p2.org> Phone: 202466-P2P2

• P2 GEMS. This site, an Internetsearch tool operated by theMassachusetts Toxics Use ReductionInstitute, can help facility planners,engineers, and managers locateprocess and materials managementinformation over the Web. It includesinformation on over 550 sites valu-able for toxics use reduction planningand pollution prevention.<www.edu/p2gems.org>

• Pollution Prevention InformationClearinghouse (PPIC). PPIC main-

tains a collection of EPA non-regula-tory documents related to wastereduction. <www.epa.gov/opptintr/library/libppic.htm> Phone: 202260-1023 e-mail: [email protected]

• U.S. Department of Energy (DOE)Industrial Assessment Centers(IACs). DOE’s Office of IndustrialTechnologies sponsors free industrialassessments for small and medium-sized manufacturers. Teams of engi-neering students from the centersconduct energy audits or industrialassessments and provide recommen-dations to manufacturers to helpthem identify opportunities toimprove productivity, reduce waste,and save energy. <www.oit.doe.gov/iac>

What Types of Technical

Assistance Are Available?

Many state and local governments havetechnical assistance programs that are distinctfrom regulatory offices. In addition, non-governmental organizations conduct a widerange of activities to educate businesses aboutthe value of pollution prevention. Theseefforts range from providing onsite technicalassistance and sharing industry-specific expe-riences to conducting research and develop-ing education and outreach materials onwaste reduction topics. The following exam-ples illustrate what services are available:

• NIST technical centers. There areNIST-sponsored ManufacturingTechnology Centers throughout thecountry as part of the grassrootsManufacturing Extension Partnership(MEP) program. The MEP programhelps small and medium-sized com-panies adopt new waste reduction


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technologies by providing technicalinformation, financing, training, andother services. The NIST Web site<www.nist.gov> has a locator thatcan help you find the nearest center.

• Trade associations. Trade associa-tions provide industry-specific assis-tance through publications,workshops, field research, and con-sulting services. EPA’s WasteWiseprogram <www.ergweb.com/wwta/intro.asp> provides an onlineresources directory which can helpyou locate specific trade associations.The National Trade and ProfessionalAssociations of the Unites States’Directory of Trade Associations(Washington, DC: Columbia Books,Inc., 2000) is another useful resource.

• Onsite technical assistance audits.These audits are for small (and some-times larger) businesses. The assess-ments, which take place outside ofthe regulatory environment and on astrictly voluntary basis, provide busi-nesses with information on how tosave money, increase efficiency, andimprove community relations. DOE’sOffice of Industrial Technologies<www.oit.doe.gov/iac> providessuch assessments for small and medium-sized manufacturers.

• Information clearinghouses. Manyorganizations maintain repositories ofwaste reduction information andserve as starting points to help busi-nesses access this information. EPA’sPollution Prevention InformationCenter (PPIC) <www.epa.gov/oppt-intr/library/libppic.htm> is oneexample.

• Facility planning assistance. A num-ber of organizations can help busi-

nesses develop, review, or evaluatefacility waste reduction plans. Statewaste reduction programs frequentlyprepare model plans designed todemonstrate activities a business canimplement to minimize waste.

• Research and collaborative pro-jects. Academic institutions, stateagencies and other organizations fre-quently participate in research andcollaborative projects with industryto foster development of wastereduction technologies and manage-ment strategies. Laboratory and fieldresearch activities include studies,surveys, database development, datacollection, and analysis.

• Hotlines. Some states operate tele-phone assistance services to providetechnical waste reduction informationto industry and the general public.Hotline staff typically answer ques-tions, provide referrals, and distributeprinted technical materials on request.

• Computer searches and theInternet. The Internet brings manypollution prevention resources to auser’s fingertips. The wide range ofresources available electronically canprovide information about innovativewaste-reducing technologies, efficientindustrial processes, current stateand federal regulations, and manyother pertinent topics. Independentsearches can be done on the Internet,and some states perform computersearches to provide industry withinformation about waste reduction.EPA and many state agencies haveWeb sites dedicated to these topics,with case studies, technical explana-tions, legal information, and links toother sites for more information.

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• Workshops, seminars, and training.State agencies, trade associations, andother organizations conduct work-shops, seminars, and technical train-ing on waste reduction. These eventsprovide information, identifyresources, and facilitate networking.

• Grants and loans. A number ofstates distribute funds to independentgroups that conduct waste reductionactivities. These groups often usesuch support to fund research and torun demonstration and pilot projects.


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To address pollution prevention you should:

■■■■ Make waste management decisions by considering the priorities set by the full range of pollutionprevention options—first, source reduction; second, reuse and recycling; third, treatment; last, dis-posal.

■■■■ Explore the cost savings and other benefits available through activities that integrate pollution pre-vention.

■■■■ Develop a waste reduction policy.

■■■■ Conduct a pollution prevention opportunity assessment of facility processes.

■■■■ Research potential pollution prevention activities.

■■■■ Consult with public and private agencies and organizations providing technical and financial assis-tance for pollution prevention activities.

■■■■ Plan and implement activities that integrate pollution prevention.

Integrating PollutionPrevention Activity List

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3-15

Erickson, S. and King, B. 1999. Fundamentals of Environmental Management. John Wiley and Sons,Inc.

Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc.

“Green Consumerism: Commitment Remains Strong Despite Economic Pessimism.” 1992. CambridgeReports. Research International. (October).

Habicht, F. Henry. 1992. U.S. EPA Memorandum on EPA Definition of Pollution Prevention (May).

Higgins, Thomas E., ed. 1995. Pollution Prevention Handbook. CRC-Lewis Publishers.

“Moving from Industrial Waste to Coproducts.” 1997. Biocycle. (January)

National Pollution Prevention Roundtable. 1995. The Pollution Prevention Yellow Pages.

Pollution Prevention Act of 1990. (42 U.S.C. 13101 et seq., Pub.L. 101-508, November 5, 1990).

Rossiter, Alan P., ed. 1995. Waste Minimization Through Process Design. McGraw-Hill, Inc.

U.S. EPA. 2001. Pollution Prevention Clearinghouse: Quarterly List of Pollution PreventionPublications, Winter 2001. EPA742-F-01-004.

U.S. EPA. 1998. Project XL: Good for the Environment, Good for Business, Good for Communities.EPA100–F-98-008.

U.S. EPA. 1997. Developing and Using Production Adjusted Measurements of Pollution Prevention.EPA600-R-97-048.

U.S. EPA. 1997. Guide to Accessing Pollution Prevention Information Electronically. EPA742-B-97-003

U.S. EPA. 1997. Pollution Prevention 1997: A National Progress Report. EPA742-R-97-001.

U.S. EPA. 1997. Technical Support Document for Best Management Practices Programs—SpentPulping Liquor Management, Spill Prevention, and Control.

U.S. EPA. 1996. Environmental Accounting Project: Quick Reference Fact Sheet. EPA742-F-96-001.

Resources

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U.S. EPA. 1996. Profiting from Waste Reduction in Your Small Business. EPA742-B-88-100.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofPaints and Coatings. EPA600-S-95-009.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofBourbon Whiskey. EPA600-S-95-010.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofAutomotive Battery Separators. EPA600-S-95-011.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofAutomotive Lighting Equipment and Accessories. EPA600-S-95-012.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofLocking Devices. EPA600-S-95-013.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofCombustion Engine Piston Rings. EPA600-S-95-015.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofMetal Fasteners.EPA600-S-95-016.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofStainless Steel Pipes and Fittings. EPA600-S-95-017.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofOutboard Motors. EPA600-S-95-018.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofElectroplated Truck Bumpers. EPA600-S-95-019.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Printed CircuitBoard Plant.EPA600-S-95-020.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofFolding Paperboard Cartons. EPA600-S-95-021.

Resources (cont.)


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U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofRebuilt Industrial Crankshafts. EPA600-S-95-022.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofPressure-sensitive Adhesive Tape. EPA600-S-95-023.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofWooden Cabinets. EPA600-S-95-024.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofPower Supplies. EPA600-S-95-025.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofFood Service Equipment. EPA600-S-95-026.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Metal PartsCoater. EPA600-S-95-027.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofGear Cases for Outboard Motors. EPA600-S-95-028.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofElectrical Load Centers. EPA600-S-95-029.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofPharmaceuticals. EPA600-S-95-030.

U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer ofAircraft Landing Gear. EPA600-S-95-032.

U.S. EPA. 1995. EPA Standards Network Fact Sheet: Role of Voluntary Standards. EPA741-F-95-005.

U.S. EPA. 1995. Introduction to Pollution Prevention: Training Manual. EPA742-B-95-003.

U.S. EPA. 1995. Recent Experience in Encouraging the Use of Pollution Prevention in EnforcementSettlements: Final Report. EPA300-R-95-006.

U.S. EPA. 1995. Recycling Means Business. EPA530-K-95-005.

Resources (cont.)

U.S. EPA. 1994. Final Best Demonstrated Available Technology (BDAT) Background Document forUniversal Standards, Volume B: Universal Standards for Wastewater forms of Listed Hazardous Wastes,Section 5, Treatment Performance Database. EPA530-R-95-033.

U.S. EPA. 1994. Review of Industrial Waste Exchanges. EPA530-K-94-003.

U.S. EPA. 1993. Guidance Manual for Developing Best Management Practices. EPA833-B-93-004.

U.S. EPA. 1993. Primer for Financial Analysis of Pollution Prevention Projects. EPA600-R-93-059.

U.S. EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-008.

U.S. EPA. 1992. Practical Guide to Pollution Prevention Planning for the Iron and Steel Industries.EPA742-B-92-100

U.S. EPA. 1991. Pollution Prevention Strategy. EPA741-R-92-001.

U.S. EPA. 1991. Treatment Technology Background Document; Third Third; Final. EPA530-SW-90-059Z.

U.S. EPA. 1990. Guide to Pollution Prevention: Printed Circuit Board Manufacturing Industry. EPA625-7-90-007

U.S. EPA. 1990. Waste Minimization: Environmental Quality with Economic Benefits. EPA530-SW-90-044.

U.S. EPA. 1989. Treatment Technology Background Document; Second Third; Final. EPA530-SW-89-048A.

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Resources (cont.)


Chapter 4Considering the Site

Contents

I. General Siting Considerations ....................................................................................................................4 - 3

A. Floodplains ............................................................................................................................................4 - 3

B. Wetlands................................................................................................................................................4 - 6

C. Active Fault Areas ................................................................................................................................4 - 10

D. Seismic Impact Zones ..........................................................................................................................4 - 12

E. Unstable Areas ....................................................................................................................................4 - 14

F. Airport Vicinities..................................................................................................................................4 - 18

G. Wellhead Protection Areas ..................................................................................................................4 - 19

II. Buffer Zone Considerations ..................................................................................................................4 - 20

A. Recommended Buffer Zones ................................................................................................................4 - 21

B. Additional Buffer Zones ......................................................................................................................4 - 22

III. Local Land Use and Zoning Considerations ..........................................................................................4 - 23

IV. Environmental Justice Considerations ..................................................................................................4 - 23

Considering the Site Activity List ................................................................................................................4 - 25

Resources ....................................................................................................................................................4 - 27

Appendix: State Buffer Zone Considerations ..............................................................................................4 - 30

Tables:

Table 1: Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions ..................4 - 12

Getting Started—Considering the Site

4-1

Many hydrologic and geologicsettings can be effectively uti-lized for protective wastemanagement. There are,however, some hydrologic

and geologic conditions that are best avoidedall together if possible. If they cannot beavoided, special design and construction pre-cautions can minimize risks. Floodplains,

earthquake zones, unstable soils, and areas atrisk for subsurface movement need to betaken into account just as they would bewhen siting and constructing a manufactur-ing plant or home. Catastrophic events asso-ciated with these locations could seriouslydamage or destroy a waste management unit,release contaminants into the environment,and add substantial expenses for cleanup,repair, or reconstruction. If problematic siteconditions cannot be avoided, engineeringdesign and construction techniques canaddress some of the concerns raised by locat-ing a unit in these areas.

Many state, local, and tribal governmentsrequire buffer zones between waste manage-ment units and other nearby land uses. Evenif buffer zones are not required, they can stillprovide benefits now and in the future. Bufferzones provide time and space to contain andremediate accidental releases before theyreach sensitive environments or sensitivepopulations. Buffer zones also help maintaingood community relations by reducing dis-ruptions associated with noise, traffic, and

Considering the SiteThis chapter will help you:

• Become familiar with environmental, geological, and manmade fea-

tures that influence siting decisions.

• Identify nearby areas or land uses that merit buffer zones and place

your unit an appropriate distance from them.

• Comply with local land use and zoning restrictions, including any

amendments occurring during consideration of potential sites.

• Understand existing environmental justice issues as you consider a

new site.

• Avoid siting a unit in hydrologic or geologic problem areas, without

first designing the unit to address conditions in those areas.

This chapter will help address the follow-ing questions:

• What types of sites need special consid-eration?

• How will I know whether my wastemanagement unit is in an area requir-ing special consideration?

• Why should I be concerned about sit-ing a waste management unit in suchareas?

• What actions can I take if I plan to sitea unit in these areas?

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wind-blown dust, often the source of seriousneighborhood concerns.

In considering impacts on the surroundingcommunity, it is important to understandwhether the community, especially one with alarge minority and low income population,already faces significant environmentalimpacts from existing industrial activities. Youshould develop an understanding of the com-munity’s current environmental problems andwork together to develop plans that canimprove and benefit the environment, thecommunity, the state, and the company.

How should a wastemanagement unit siteassessment begin?

In considering whether to site a new wastemanagement unit or laterally expand an exist-ing unit, certain factors will influence the sit-ing process. These factors include landavailability, distance from waste generationpoints, ease of access, local climatic condi-tions, economics, environmental considera-tions, local zoning requirements, and potentialimpacts on the community. As prospectivesites are identified, you should become famil-iar with the siting considerations raised in thischapter. Determine how to address concerns ateach site to minimize a unit’s adverse impactson the environment in addition to the environ-ment’s adverse impacts on the unit. You shouldchoose the site that best balances protection ofhuman health and the environment with oper-ational goals. In addition to considering theissues raised in this chapter, you should checkwith state and local regulatory agencies earlyin the siting process to identify other issuesand applicable restrictions.

Another factor to consider is whether thereare any previous or current contaminationproblems at the site. It is recommended thatpotential sites for new waste managementunits be free of any contamination problems.An environmental site assessment (ESA) may

be required prior to the disturbance of anyland area or before property titles are trans-ferred. An ESA is the process of determiningwhether contamination is present on a parcelof property. You should check with the EPAregional office and state or local authorities todetermine if there are any ESA requirementsprior to siting a new unit or expanding anexisting unit. If there are no requirements,you might want to consider performing anESA in order to ensure that there are no cont-amination problems at the site.

Many companies specialize in site screening,characterization, and sampling of differentenvironmental media (i.e., air, water, soil) forpotential contamination. A basic ESA (oftenreferred to as the Phase I Environmental SiteAssessment process) typically involvesresearching prior land use, deciding if sam-pling of environmental media is necessarybased on the prior activities, and determiningcontaminate fate and transport if contamina-tion has occurred. Liability issues can arise ifthe site had contamination problems prior toconstruction or expansion of the waste man-agement unit. Information on the extent ofcontamination is needed to quantify cleanupcosts and determine the cleanup approach.Cleanup costs can represent an additional,possibly significant, project cost when siting awaste management unit.

As discussed later in this chapter, you willalso need to consider other federal laws andregulations that could affect siting. For exam-ple, the Endangered Species Act (16 USCSections 1531 et seq.) provides for the desig-nation and protection of threatened or endan-gered wildlife, fish, and plant species, andensures the conservation of the ecosystems onwhich such species depend. It is the responsi-bility of the facility manager to check withand obtain a Section 10 permit from theSecretary of the Interior if the construction oroperation of a waste management unit mightpotentially impact any endangered or threat-


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1 This agency of the U.S. Department of Agriculture was formerly known as the Soil ConservationService (SCS).

ened species or its critical habitat. Thus, youmight not be able to site a new waste man-agement unit in an area where endangered orthreatened species live, or expand an existingunit into such an area. As another example,the National Historic Preservation Act (16USC Sections 470 et seq.) protects historicsites and archaeological resources. The facilitymanager of a waste management unit shouldbe aware of the properties listed on theNational Register of Historic Properties. Thefacility manager should consult with the statehistoric preservation office to ensure that theproperty to be used for a new unit or lateralexpansion of an existing unit will not impactlisted historic properties, or sites with archeo-logical significance. Other federal laws orstatutes might also require consideration. It isthe ultimate responsibility of the facilityowner or manager to comply with therequirements of all applicable federal andstate statutes when siting a waste manage-ment unit.

Additional factors, such as proximity toother activities or sites that affect the environ-ment, also might influence siting decisions.To determine your unit’s proximity to otherfacilities or industrial sites, you can utilizeEPA’s Envirofacts Warehouse. The EnvirofactsWeb site at <www.epa.gov/enviro/index_java.html> provides users with access to sev-eral EPA databases that will provide you withinformation about various environmentalactivities including toxic chemical releases,water discharges, hazardous waste handlingprocesses, Superfund status, and air releases.The Web site allows you to search one data-base or several databases at a time about aspecific location or facility. You can also cre-ate maps that display environmental informa-tion using the “Enviromapper” applicationlocated at <www.epa.gov/enviro/html/mod/index.html>. Enviromapper allows users tomap different types of environmental infor-mation, including the location of drinking

water supplies, toxic and air releases, haz-ardous waste sites, water discharge permits,and Superfund sites at the national, state, andcounty levels.

EPA’s Waste Management—Facility SitingApplication is a powerful new Web-basedtool that provides assistance in locating wastemanagement facilities. The tool allows theuser to enter a ZIP code; city and state; or lat-itude and longitude to identify the location offault lines, flood planes, wetlands, and karstterrain in the selected area. The user also canuse the tool to display other EPA regulatedfacilities, monitoring sites, water bodies, andcommunity demographics. The Facility SitingApplication can be found at <www.epa.gov/epaoswer/non-hw/industd/index.htm>.

I. General SitingConsiderations

Examining the topography of a site is thefirst step in siting a unit. Topographic infor-mation is available from the U.S. GeologicalSurvey (USGS), the Natural ResourcesConservation Service (NRCS)1, the state’s geo-logical survey office or environmental regula-tory agency, or local colleges and universities.Remote sensing data or maps from these orga-nizations can help you determine whetheryour prospective site is located in any of theareas of concern discussed in this section.USGS maps can be downloaded or orderedfrom their Web site at <mapping.usgs.gov>.Also, the University of Missouri-Rolla main-tains a current list of state geological surveyoffices on its library’s Web site at<www.umr.edu/~library/geol/geoloff.html>.

A. FloodplainsA floodplain is a relatively flat, lowland

area adjoining inland and coastal waters. The

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100-year floodplain—the area susceptible toinundation during a large magnitude floodwith a 1 percent chance of recurring in anygiven year—is usually the floodplain of con-cern for waste management units. You shoulddetermine whether a candidate site is in a100-year floodplain. Siting a waste manage-ment unit in a 100-year floodplain increasesthe likelihood of floods inundating the unit,increases the potential for damage to liner sys-tems and support components (e.g., leachatecollection and removal systems or other unitstructures), and presents operational concerns.This, in turn, creates environmental andhuman health and safety concerns, as well aslegal liabilities. It can also be very costly tobuild a unit to withstand a 100-year floodwithout washout of waste or damage to theunit, or to reconstruct a unit after such aflood. Further, locating your unit in a flood-plain can exacerbate the damaging effects of aflood, both upstream and downstream, byreducing the temporary water storage capacityof the floodplain. As such, it is preferable tolocate potential sites outside the 100-yearfloodplain.

How is it determined if aprospective site is in a 100-yearfloodplain?

The first step in determining whether aprospective site is located in a 100-year flood-plain is to consult with the Federal EmergencyManagement Agency (FEMA). FEMA has pre-pared flood hazard boundary maps for mostregions. If a prospective site does not appearto be located in a floodplain, further explo-ration is not necessary. If uncertainty exists asto whether the prospective site might be in afloodplain, several sources of information areavailable to help make this determination.More detailed flood insurance rate maps(FIRMs) can be obtained from FEMA. FIRMsdivide floodplain areas into three zones: A, B,and C. Class A zones are the most susceptibleto flooding while class C zones are the leastsusceptible. FIRMs can be obtained fromFEMA’s Web site at <msc.fema.gov/MSC/hardcopy.htm>.

Additional information can be found onflood insurance rate maps in FEMA’s publica-tion How to Read a Flood Insurance Rate Map(visit: <www.fema.gov/nfip/ readmap.htm>).FEMA also publishes The National FloodInsurance Program Community Status Bookwhich lists communities with flood insurancerate maps or floodway maps. Floodplain mapscan also be obtained through the USGeological Survey (USGS); National ResourcesConservation Service (NRCS); the Bureau ofLand Management; the Tennessee ValleyAuthority; and state, local, and tribal agencies.2

Note that river channels shown in flood-plain maps can change due to hydropower orflood control projects. As a result, some flood-plain boundaries might be inaccurate. If yoususpect this to be the case, consult recent aeri-al photographs to determine how river chan-nels have been modified.

2 Copies of flood maps from FEMA are available at Map Service Center, P.O. Box 1038, Jessup, MD 20794-1038, by phone 800 358-9616, or the Internet at <www.fema.gov/nfip/readmap.htm>.

Flood waters overflowed from theMississippi River (center) into its floodplain(foreground) at Quincy, Illinois in the 1993

floods that exceeded 100-year levels in partsof the Midwest.


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If maps cannot be obtained, anda potential site is suspected to belocated in a floodplain, you canconduct a field study to delineatethe floodplain and determine thefloodplain’s properties. To performa delineation, you can draw onmeteorological records and physio-graphic information, such as exist-ing and planned watershed landuse, topography, soils and geo-graphic mapping, and aerial photo-graphic interpretation of landforms. Additionally, you can usethe U.S. Water Resources Council’smethods of determining floodpotential based on stream gaugerecords, or you can estimate thepeak discharge to approximate theprobability of exceeding the 100-year flood. Contact the USGS,Office of Surface Water, for addi-tional information concerningthese methods.3

What can be done if aprospective site is in afloodplain?

If a new waste management unitor lateral expansion will be sited ina floodplain, design the unit to pre-vent the washout of waste, avoid sig-nificant alteration of flood flow, and maintainthe temporary storage capacity of the flood-plain. Engineering models can be used toestimate a floodplain’s storage capacity andfloodwater flow velocity. The U.S. ArmyCorps of Engineers (USACE) HydrologicEngineering Center has developed severalcomputer models for simulating flood prop-erties.4 The models can predict how a wastemanagement unit sited in a floodplain canaffect its storage capacity and can also simu-late flood control structures and sediment

transport. If a computer model predicts thatplacement of the waste management unit inthe floodplain raises the base flood level bymore than 1 foot, the unit might alter thestorage capacity of the floodplain. If design-ing a new unit, you should site it to minimizethese effects. The impact of your unit’s loca-tion on the speed and flow of flood watersdetermines the likelihood of waste washout.To quantify this, estimate the shear stress onthe unit’s support components caused by theimpinging flood waters at the depth, velocity,

3 Information on stream gaging and flood forecasting can be obtained from the USGS, Office of SurfaceWater, at 413 National Center, Reston, VA 22092, by phone 703 648-5977, or the Internet at<water.usgs.gov>.

4 The HEC-1, HEC-2, HEC-5, and HEC-6 software packages are available free of charge through theUSACE Web site at <http://www.hec.usace.army.mil/software/software_distrib/>.

FEMA provides flood maps like this one for most floodplainsSource: FEMA, Q3 Flood Data Users Guide <www.fema.gov/msc>.

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and duration associated with the peak (i.e.,highest) flow period of the flood.

While these methods can help protectyour unit from flood damage and washout,be aware that they can further contribute to adecrease in the water storage and flow capac-ity of the floodplain. This, in turn, can raisethe level of flood waters not only in your areabut in upstream and downstream locations,increasing the danger of flood damage andadding to the cost of flood control programs.Thus, serious consideration should be givento siting a waste management unit outside a100-year floodplain.

B. WetlandsWetlands, which include swamps, marshes,

and bogs, are vital and delicate ecosystems.They are among the most productive biologi-cal communities on earth and provide habitatfor many plants and animals. The U.S. Fishand Wildlife Service estimates that up to 43percent of all endangered or threatenedspecies rely on wetlands for their survival.5

5 From EPA’s Wetlands Web site, Values and Functions of Wetlands factsheet, <www.epa.gov/owow/wetlands/facts/fact2.html>.

Riprap (rock cover) reduces stream channel erosion (left) and gabions (crushed rock encasedin wire mesh) help stabilize erodible slopes (right).

Sources: U.S. Department of the Interior, Office of Surface Mining (left); The ConstructionSite—A Directory To The Construction Industry (right).

Knowing the behavior of waters at theirpeak flood level is important for determin-

ing whether waste will wash out.


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6 For the full text of the Clean Water Act, including Section 404, visit the U.S. House of RepresentativesInternet Law Library Web site at <uscode.house.gov/download.htm>, under Title 33, Chapter 26.

Wetlands protect water quality by assimilatingwater pollutants, removing sediments contain-ing heavy metals, and recharging ground-water supplies. Wetlands also preventpotentially extensive and costly floods by tem-porarily storing flood waters and reducingtheir velocity. These areas also offer numerousrecreational opportunities.

Potential adverse impacts associated withlocating your unit in a wetland include dewa-tering the wetland (i.e., causing removal ordrainage of water), contaminating the wet-land, and causing loss of wetland acreage.Damage could also be done to important wet-land ecosystems by destroying their aestheticqualities and diminishing wildlife breedingand feeding opportunities. Siting in a wetlandincreases the potential for damage to yourunit, especially your liner system and struc-tural components, as a result of ground set-

tlement, action of the high water table, andflooding. Alternatives to siting a waste man-agement unit in a wetland area should begiven serious consideration based uponSection 404 requirements in the Clean WaterAct (CWA) as discussed below.

If a waste management unit is to be sited ina wetland area, the unit will be subject toadditional regulations. In particular, Section404 of the Clean Water Act (CWA) authorizesthe Secretary of the Army, acting through theChief of Engineers, to issue permits for thedischarge of dredged or fill material into wet-lands and other waters of the United States.6

Activities in waters of the United States regu-lated under this permitting program include“placement of fill material for construction ormaintenance of any liner, berm, or otherinfrastructure associated with solid wastelandfills,” as well as fills for development,water resource projects, infrastructureimprovements, and conversion of wetlands touplands for farming and forestry (40 CFRSection 232.2—definition of “discharge of fillmaterial”). EPA regulations under Section 404(33 United States Code Section 1344) stipu-lates that no discharge of dredged or fill mate-rial can be permitted if a practicablealternative exists that is less damaging to theaquatic environment or if the nation’s waterswould be significantly degraded. Therefore, in

Different types of wetlands: spruce bog (left) and eco pond in the Florida Everglades (right).

For regulatory purposes under the CleanWater Act, wetlands are defined as areas“that are inundated or saturated by sur-face or ground water at a frequency andduration sufficient to support, and thatunder normal circumstances do support,a prevalence of vegetation typically adapt-ed for life in saturated soil conditions.”

40 Code of Federal Regulations (CFR) 232.2(r)

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7 To contact NWI, write to National Wetlands Inventory Center, 9720 Executive Center Drive, Suite 101,Monroe Building, St. Petersburg, FL 33702, call 727 570-5400, or fax 727 570-5420. For additionalinformation online or to search for maps of your area, visit: <www.nwi.fws.gov>.

compliance with the guidelines establishedunder Section 404, all permit applicants must:

• Take steps to avoid wetland impactswhere practicable.

• Minimize impacts to wetlands wherethey are unavoidable.

• Compensate for any remaining,unavoidable impacts by restoring orcreating wetlands.

The EPA and USACE jointly administer areview process to issue permits for regulatedactivities. For projects with potentially signifi-cant impacts, an individual permit is usuallyrequired. For most discharges with only mini-mal adverse effects, USACE may allow appli-cants to comply with existing generalpermits, which are issued on a nationwide,regional, or statewide basis for particularactivity categories as a means to expedite thepermitting process. In making permittingdecisions, the agencies will consider otherfederal laws that might restrict placement ofwaste management units in wetlands. Theseinclude the Endangered Species Act; theMigratory Bird Conservation Act; the CoastalZone Management Act; the Wild and ScenicRivers Act; the Marine Protection, Researchand Sanctuaries Act; and the NationalHistoric Preservation Act.

How is it determined if aprospective site is in a wetland?

As a first step, determine if the prospectivesite meets the definition of a wetland. If theprospective site does not appear to be a wet-land, then no further exploration is necessary.If it is uncertain whether the prospective siteis a wetland, then several sources are avail-able to help you make this determination anddefine the boundaries of the wetland.Although this can be a challenging process, itwill help you avoid future liability since fill-ing a wetland without the appropriate federal,

state, or local permits would be a violation ofmany laws. It might be possible to learn theextent of wetlands without performing a newdelineation, since many wetlands have previ-ously been mapped. The first step, therefore,should be to determine whether wetlandsinformation is available for your area.

At the federal level, four agencies are prin-cipally involved with wetlands identificationand delineation: USACE, EPA, the U.S. Fishand Wildlife Service (FWS), and NationalResource Conservation Service (NRCS). EPAalso has a Wetlands Information Hotline (800832-7828) and a wetlands Web site at <www.epa.gov/owow/wetlands> which providesinformation about EPA’s wetlands program;facts about wetlands; the laws, regulations,and guidance affecting wetlands; and science,education, and information resources for wet-lands. The local offices of NRCS (in agricul-tural areas) or regional USACE EngineerDivisions and Districts <www.usace.army.mil/divdistmap.html> might know whetherwetlands in the vicinity of the potential sitehave already been delineated.

Additionally, FWS maintains the NationalWetlands Inventory (NWI) Center,7 fromwhich you can obtain wetlands mapping formuch of the United States. This mapping,however, is based on aerial photography,which is not reliable for specific field deter-minations. If you have recently purchasedyour site, you also might be able to find outfrom the previous property owner whetherany delineation has been completed thatmight not be on file with these agencies. Evenif existing delineation information for the siteis found, it might still be prudent to contact aqualified wetlands consultant to verify thewetland boundaries, especially if the delin-eation is not a field determination or is morethan a few years old.

If the existence of a wetland is uncertain,you should obtain a wetlands delineation.


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8 Currently, there is no federal certification program. In March 1995, USACE proposed standards for aWetlands Delineator Certification Program (WDCP), but the standards have not been finalized. If theWDCP standards are finalized and implemented, you should use WDCP-certified wetland consultants.

9 The 1987 manual can be ordered from the National Technical Information Service (NTIS) at 703 605-6000 or obtained online at <www.wes.army.mil/el/wetlands/wlpubs.html>.

This procedure should be performed only byan individual with experience in performing awetlands delineation8 using standard delin-eation procedures or applicable state or localdelineation standards. The delineation proce-dure, with which you should become familiarbefore hiring a delineator, involves collectingmaps, aerial photographs, plant data, soil sur-veys, stream gauge data, land use data, andother information. Note that it is mandatorythat wetlands delineation for CWA Section404 permitting purposes be conducted inaccordance with the 1987 U.S. Army Corps ofEngineers Wetlands Delineation Manual9

(USACE, 1991). The manual provides guide-lines and methods for determining whetheran area is a wetland for purposes of Section404. A three-parameter approach for assess-

ing the presence and location of hydrophyticvegetation (i.e., plants that are adapted for lifein saturated soils), wetland hydrology, andhydric soils is discussed.

What can be done if aprospective site is in a wetland?

Before constructing a waste managementunit in a wetland area, consider whether youcan locate the unit elsewhere. If an alternativelocation can be identified, strongly considerpursuing such an option, as required bySection 404 of the CWA. Because wetlandsare important ecosystems that should be pro-tected, identification of practicable locationalternatives is a necessary first step in the sit-ing process. Even if no viable alternative loca-

NWI wetland resource maps like this one show the locations of various different types of wetlands and are available for many areas.

Source: NWI web site, sample GIS Think Tank maps page, <wetlands.fws.gov/>.

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10 Information about ordering these maps is available by calling 888 ASK-USGS or 703 648-6045.

11 The National Aerial Photographic Program (NAPP) and the National High Altitude Program (NHAP),both administered by USGS, are sources of aerial photographs. To order from USGS, call 605 594-6151. For more information, see <edc.usgs.gov/nappmap.html>. Local aerial photography firms andsurveyors are also good sources of information.


tions are identified, it might be beneficial tokeep a record of the alternatives investigated,noting why they were not acceptable. Suchrecords might be useful during the interac-tion between facilities, states, and members ofthe community.

If no alternatives are available, you shouldconsult with state and local regulatory agen-cies concerning wetland permits. Most statesoperate permitting programs under the CWA,and state authorities can guide you throughthe permitting process. To obtain a permit,the state might require that the unit facilitymanager assess wetland impacts and then:

• Prevent contamination from leachateand runoff.

• Minimize dewatering effects.

• Reduce the loss of wetland acreage.

• Protect the waste management unitagainst settling.

C. Active Fault AreasFaults occur when stresses in a geologic

material exceed its ability to withstand theseforces. Areas surrounding faults are subject toearthquakes and ground failures, such aslandslides or soil liquefaction. Fault move-ment can directly weaken or destroy struc-tures, or seismic activity associated withfaulting can cause damage to structuresthrough vibrations. Structural damage to thewaste management unit could result in therelease of contaminants. In addition, faultmovement might create avenues to ground-water supplies, increasing the risk of ground-water contamination.

Liquefaction is another common problemencountered in areas of seismic activity. Thevibrating motions caused by an earthquaketend to rearrange the sand grains in soils. If

the grains are saturated, the saturated granu-lar material turns into a viscous fluid, aprocess referred to as liquefaction. Thisdiminishes the bearing capacity of the soilsand can lead to foundation and slope failures.

To avoid these hazards, do not build orexpand a unit within 200 feet of an activefault. If it is not possible to site a unit morethan 200 feet from an active fault, you shoulddesign the unit to withstand the potentialground movement associated with the faultarea. A fault is considered active if there hasbeen movement along it within the last 10,000to 12,000 years.

How is it determined if aprospective site is in a fault area?

A series of USGS maps, Preliminary YoungFault Maps, Miscellaneous Field Investigation916, identifies active faults.10 These maps,however, might not be completely accuratedue to recent shifts in fault lines. If a prospec-tive site is well outside the 200 foot area ofconcern, no fault area considerations exist. Ifit is unclear how close a prospective site is toan active fault, further evaluation will be nec-essary. A geologic reconnaissance of the siteand surrounding areas can be useful in verify-ing that active faults do not exist at the site.

If a prospective site is in an area known orsuspected to be prone to faulting, you shouldconduct a fault characterization to determineif the site is near a fault. A characterizationincludes identifying linear features that sug-gest the presence of faults within a 3,000-footradius of the site. Such features might beshown or described on maps, aerial pho-tographs,11 logs, reports, scientific literature,or insurance claim reports, or identified by adetailed field reconnaissance of the area.

If the characterization study reveals faultswithin 3,000 feet of the proposed unit or lat-


4-11

eral expansion, you should conduct furtherinvestigations to determine whether any ofthe faults are active within 200 feet of theunit. These investigations can involve drillingand trenching the subsurface to locate faultzones and evidence of faulting. Perpendiculartrenching should be used on any fault within200 feet of the proposed unit to examine theseismic epicenter for indications of recentmovement.

What can be done if a prospectivesite is in a fault area?

If an active fault exists on the site wherethe unit is planned, consider placing the unit200 feet back from the fault area. Even withsuch setbacks, only place a unit in a fault areaif it is possible to ensure that no damage to

the unit’s structural integrity would result. Asetback of less than 200 feet might be ade-quate if ground movement would not damagethe unit.

If a lateral expansion or a new unit will belocated in an area susceptible to seismic activ-ity, there are two particularly important issuesto consider: horizontal acceleration andmovement affecting side slopes. Horizontalacceleration becomes a concern when a loca-tion analysis reveals that the site is in a zonewith a risk of horizontal acceleration in therange of 0.1 g to 0.75 g (g = acceleration ofgravity). In these zones, the unit designshould incorporate measures to protect theunit from potential ground shifts. To addressside slope concerns, you should conduct aseismic stability analysis to determine themost effective materials and gradients for pro-tecting the unit’s slopes from any seismicinstabilities. Also, design the unit to with-stand the impact of vertical accelerations.

If the unit is in an area susceptible to liq-uefaction, you should consider groundimprovement measures. These measuresinclude grouting, dewatering, heavy tamping,and excavation. See Table 1 for examples oftechniques that are currently used.

Additional engineering options for faultareas include the use of flexible pipes forrunoff and leachate collection, and redundantcontainment systems. In the event of founda-tion soil collapse or heavy shifting, flexiblerunoff and leachate collection pipes—alongwith a bedding of gravel or permeable materi-al—can absorb some of the shifting-relatedstress to which the pipes are subjected. Alsoconsider a secondary containment measure,such as an additional liner system. In earth-quake-like conditions, a redundancy of thisnature might be necessary to prevent contam-ination of the surrounding area if the primaryliner system fails.

In this aerial view, the infamous San Andreasfault slices through the Carrizo Plain east of

San Luis Obispo, California.

Source: USGS.

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D. Seismic Impact ZonesA seismic impact zone is an area having a

2 percent or greater probability that the maxi-mum horizontal acceleration caused by anearthquake at the site will exceed 0.1 g in 50years. This seismic activity can damageleachate collection and removal systems, leakdetection systems, or other unit structuresthrough excessive bending, shearing, tension,and compression. If a unit’s structural compo-nents fail, leachate can contaminate sur-rounding areas. Therefore, for safety reasons,it is recommended that a unit not be located

in a seismic impact zone. If a unit must besited in a seismic impact zone, the unitshould be designed to withstand earthquake-related hazards, such as landslides, slope fail-ures, soil compaction, ground subsidence,and soil liquefaction.

Additionally, if you build a unit in a seis-mic impact zone, avoid rock and soil typesthat are especially vulnerable to earthquakeshocks. These include very steep slopes ofweak, fractured, and brittle rock or unsaturat-ed loess,12 which are vulnerable to transientshocks caused by tensional faulting. Avoid

Source: RCRA Subtitle D (258) Seismic Design Guidance for Municipal Solid Waste Landfill Facilities. (EPA, 1995c).

Method Principle Most Suitable Soil ApplicationsConditions/Types

Blasting Shock waves and vibrations cause Saturated, clean sands; partly Induce liquefaction in controlled and limited liquefaction, displacement, saturated sands and silts after limited stages and increase relative density remolding, and settlement to higher flooding. to potentially nonliquefiable range. density.

Vibrocompaction Densification by vibration and Cohesionless soils with less Induce liquefaction in controlled and compaction of backfill material of sand than 20 percent fines. limited stages and increase relative density or gravel. to nonliquefiable condition. The dense

column of backfill provides (a) vertical support, (b) drainage to relieve pore water pressure, and (c) shear resistance in hori-zontal and inclined directions. Used to stabilize slopes and strengthen potential failure surfaces.

Compaction piles Densification by displacement of pile Loose sandy soils; partly Useful in soils with fines. Increases relative volume and by vibration during driving; saturated clayey soils; loess. density to nonliquefiable condition. increase in lateral effective earth Provides shear resistance in horizontal and pressure. inclined directions. Used to stabilize

slopes and strengthen potential failure surfaces.

Displacement and Highly viscous grout acts as radial All soils. Increase in soil relative density and compaction grout hydraulic jack when pumped in under horizontal effective stress. Reduce

high pressure. liquefaction potential. Stabilize the ground against movement.

Mix-in-place piles Lime, cement, or asphalt introduced Sand, silts, and clays; all soft Slope stabilization by providing shear and walls through rotating auger or special in- or loose inorganic soils. resistance in horizontal and inclined

place mixer. directions, which strengthens potential failure surfaces or slip circles. A wall could be used to confine an area of liquefiable soil.

Heavy tamping Repeated application of high- intensity Cohesionless soils best; other Suitable for some soils with fines; usable (dynamic impacts at surface. types can also be improved. above and below water. In cohesionless compaction) soils, induces liquefaction in controlled

and limited stages and increases relative density to potentially nonliquefiable range.

Table 1Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions

12 Loess is a wind-deposited, moisture-deficient silt that tends to compact when wet.

13 For information on ordering these maps, call 888 ASK-USGS, write to USGS Information Services, Box25286, Denver, CO 80225, or fax 303 202-4693. Online information is available at<ask.usgs.gov/products.html>.

14 To contact NEIC, call 303 273-8500, write to United States Geological Survey, National EarthquakeInformation Center, Box 25046, DFC, MS 967, Denver, CO 80225, fax 303 273-8450, or [email protected]. For online information, visit: <neic.usgs.gov>.


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loess and saturated sand as well, because seis-mic shocks can liquefy them, causing suddencollapse of structures. Similar effects are possi-ble in sensitive cohesive soils when naturalmoisture exceeds the soil’s liquid limit. For adiscussion of liquid limits, refer to the “SoilProperties” discussion in Chapter 7, Section B– Designing and Installing Liners. Earthquake-induced ground vibrations can also compactloose granular soils. This could result in largeuniform or differential settlements at theground surface.

How is it determined if aprospective site is in a seismicimpact zone?

If a prospective site is in an area with nohistory of earthquakes, then seismic impactzone considerations might not exist. If it isunclear whether the area has a history of seis-mic activity, then further evaluation will benecessary. As a first step, consult the USGSfield study map series MF-2120, ProbabilisticEarthquake Acceleration and Velocity Maps forthe United States and Puerto Rico.13 These mapsprovide state- and county-specific informationabout seismic impact zones. Additional infor-mation is available from the USGS NationalEarthquake Information Center (NEIC),14

which maintains a database of known earth-quake and fault zones. Further informationconcerning the USGS National Seismic HazardMapping Project can be accessed at <geohaz-ards.cr.usgs.gov/eq>. USGS’s Web site alsoallows you to find ground motion hazardparameters (including peak ground accelera-tion and spectra acceleration) for your site byentering a 5 digit ZIP code<eqint.cr.usgs.gov/eq/html/zipcode.shtml>, or a latitude-longitude coordinatepair <eqint.cr.usgs.gov/eq/html/lookup.shtml>. The USGS Web site explains howthese values can be used to determine theprobability of excedance for a particular level

of ground motion at your site. This can helpyou determine if the structural integrity of theunit is susceptible to damage from groundmotion.

For waste management unit siting purpos-es, use USGS’ recently revised PeakAcceleration (%g) with 2 % Probability ofExceedance in 50 Years maps available at <geohazards.cr.usgs.gov/eq/hazmapsdoc/junecover.html>. It is important to note thatground motion values having a 2 percentprobability of exceedance in 50 years areapproximately the same as those having 10percent probability of being exceeded in 250years. According to USGS calculations, theannual exceedance probabilities of these twodiffer by about 4 percent (for a more completediscussion visit: <geohazards.cr.usgs.gov/eq/faq/parm08.html>).

If a site is or might be in a seismic impactzone, it is useful to analyze the effects of seis-mic activity on soils in and under the unit.Computer software programs are available thatcan evaluate soil liquefaction potential(defined in Section C of this chapter). LIQ-UFAC, a software program developed by theNaval Facilities Engineering Command inWashington, DC, can calculate safety factorsfor each soil layer in a given soil profile andthe corresponding one dimensional settle-ments due to earthquake loading.

What can be done if aprospective site is in a seismicimpact zone?

If a waste management unit cannot be sitedoutside a seismic impact zone, structural com-ponents of the unit—including liners, leachatecollection and removal systems, and surface-water control systems—should be designed toresist the earthquake-related stresses expectedin the local soil. You should consult profes-sionals experienced in seismic analysis and

design to ensure that your unit is designedappropriately. To determine the potentialeffects of seismic activity on a structure, theseismic design specialist should evaluate soilbehavior with respect to earthquake intensity.This evaluation should account for soilstrength, degree of compaction, sorting (orga-nization of the soil particles), saturation, andpeak acceleration of the potential earthquake.

After conducting an evaluation of soilbehavior, choose appropriate earthquake pro-tection measures. These might include shal-lower slopes, dike and runoff control designsusing conservative safety factors, and contin-gency plans or backup systems for leachatecollection if primary systems are disrupted.Unit components should be able to withstandthe additional forces imposed by an earth-quake within acceptable margins of safety.

Additionally, well-compacted, cohesionlessembankments or reasonably flat slopes ininsensitive clay (clay that maintains its com-pression strength when remolded) are lesslikely to fail under moderate seismic shocks(up to 0.15 g - 0.20 g). Embankments madeof insensitive, cohesive soils founded oncohesive soils or rock can withstand evengreater seismic shocks. For earthen embank-ments in seismic regions, consider designingthe unit with internal drainage and corematerials resistant to fracturing. Also, prior toor during unit construction in a seismicimpact zone, you should evaluate excavationslope stability to determine the appropriategrade of slopes to minimize potential slip.

For landfills and waste piles, using shal-lower waste side slopes is recommended, assteep slopes are more vulnerable to slidesand collapse during earthquakes. Use fillsequencing techniques that avoid concentrat-ing waste in one area of the unit for anextended period of time. This prevents wastepile side slopes from becoming too steep andunstable and alleviates differential loading of

the foundation components. Placing toomuch waste in one area of the unit can leadto catastrophic shifting during an earthquakeor heavy seismic activity. Shifting of thisnature can cause failure of crucial systemcomponents or of the unit in general.

In addition, seismic impact zones havedesign issues in common with fault areas,especially concerning soil liquefaction andearthquake-related stresses. To address lique-faction, consider employing the soil improve-ment techniques described in Table 1.Treating liquefiable soils in the vicinity of theunit will improve foundation stability andhelp prevent uneven settling or possible col-lapse of heavily saturated soils underneath ornear the unit.

To protect against earthquake-relatedstresses, consider installing redundant linersand special leachate collection and removalsystem components, such as secondary linersystems, composite liners, and leak detectionsystems combined with a low permeabilitysoil layer. These measures function as back-ups to the primary containment and collec-tion systems and provide a greater margin ofsafety for units during possible seismic stress-es. Examples of special leachate systemsinclude high-strength, flexible materials forleachate containment systems; geomembraneliner systems underlying leachate contain-ment systems; and perforated polyvinyl chlo-ride or high-density polyethylene piping in abed of gravel or other permeable material.

E. Unstable AreasSiting in unstable areas should be avoided

because these locations are susceptible to nat-urally occurring or human-induced events orforces capable of impairing the integrity of awaste management unit. Naturally occurringunstable areas include regions with poor soilfoundations, regions susceptible to massmovement, or regions containing karst ter-

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rain, which can include hidden sinkholes.Unstable areas caused by human activity caninclude areas near cut or fill slopes, areaswith excessive drawdown of ground water,and areas where significant quantities of oilor natural gas have been extracted. If it isnecessary to site a waste management unit inan unstable area, technical and constructiontechniques should be considered to mitigateagainst potential damage.

The three primary types of failure that canoccur in an unstable area are settlement, lossof bearing strength, and sinkhole collapse.Settlement can result from soil compression ifyour unit is, or will be located in, an unstablearea over a thick, extensive clay layer. Theunit’s weight can force water from the com-pressible clay, compacting it and allowing theunit to settle. Settlement can increase aswaste volume increases and can result instructural failure of the unit if it was notproperly engineered. Settlement beneath awaste management unit should be assessedand compared to the elongation strength andflexibility properties of the liner and leachatecollection pipe system. Even small amountsof settlement can seriously damage leachatecollection piping and sumps. A unit shouldbe engineered to minimize the impacts of set-tlement if it is, or will be in an unstable area.

Loss of bearing strength is a failure modethat occurs in soils that tend to expand andrapidly settle or liquefy. Soil contractions andexpansions can increase the risk of leachate orwaste release. Another example of loss of bear-ing strength occurs when excavation near theunit reduces the mass of soil at the toe of theslope, thereby reducing the overall strength(resisting force) of the foundation soil.

Catastrophic collapse in the form of sink-holes can occur in karst terrain. As water,especially acidic water, percolates throughlimestone, the soluble carbonate material dis-solves, leaving cavities and caverns. Land

overlying caverns can collapse suddenly,resulting in sinkholes that can be more than100 feet deep and 300 feet wide.

How is it determined if aprospective site is in an unstable area?

If a stability assessment has not been per-formed on a potential site, you should have aqualified professional conduct one beforedesigning a waste management unit on theprospective site. The qualified professionalshould assess natural conditions, such as soilgeology and geomorphology, as well ashuman-induced surface and subsurface fea-tures or events that could cause differentialground settlement. Naturally unstable condi-tions can become more unpredictable anddestructive if amplified by human-inducedchanges to the environment. If a unit is to bebuilt at an assessed site that exhibits stabilityproblems, tailor the design to account for anyinstability detected. A stability assessmenttypically includes the following steps:

Screen for expansive soils. Expansivesoils can lose their ability to support a foun-dation when subjected to certain natural orhuman-induced events, such as heavy rain orexplosions. Expansive soils usually are clay-rich and, because of their molecular struc-ture, tend to swell and shrink by taking upand releasing water. Such soils include smec-tite (montmorillonite group) and vermiculiteclays. In addition, soils rich in white alkali(sodium sulfate), anhydrite (calcium sulfate),or pyrite (iron sulfide) can also swell as watercontent increases. These soils are more com-mon in the arid western states.

Check for soil subsidence. Soils subjectto rapid subsidence include loesses, uncon-solidated clays, and wetland soils. Unconsol-idated clays can undergo considerablecompaction when oil or water is removed.Similarly, wetland soils, which by their


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15 For information on ordering this map, call 888 ASK-USGS, write USGS Information Services, Box 25286, Denver, CO 80255, or fax 303 202-4693. Online information is available at <www-atlas.usgs.gov/atlasmap.html>.

nature are water-bearing, are also subject tosubsidence when water is withdrawn.

Look for areas subject to mass move-ment or slippage. Such areas are often situ-ated on slopes and tend to have rock or soilconditions conducive to downhill sliding.Examples of mass movements includeavalanches, landslides, and rock slides. Somesites might require cutting or filling slopesduring construction. Such activities can causeexisting soil or rock to slip.

Search for karst terrain. Karst featuresare areas containing soluble bedrock, such aslimestone or dolomite, that have been dis-solved and eroded by water, leaving charac-teristic physiographic features includingsinkholes, sinking streams, caves, largesprings, and blind valleys. The principal con-cern with karst terrains is progressive or cata-strophic subsurface failure due to thepresence of sinkholes, solution cavities, andsubterranean caverns. Karst features can alsohamper detection and control of leachate,which can move rapidly through hidden con-duits beneath the unit. Karst maps, such asEngineering Aspects of Karst, Scale 1:7,500,000,Map No. 38077-AW-NA-07M-00, produced by

the USGS15 and state specific geological mapscan be reviewed to identify karst areas.

Scan for evidence of excessive ground-water drawdown or oil and gas extraction.Removing underground water can increasethe effective overburden on the foundationsoils underneath the unit. Excessive draw-down of water might cause settlement orbearing capacityfailure on thefoundation soils.Extraction of oilor natural gascan have similareffects.

Investigatethe geotechnicaland geologicalcharacteristicsof the site. It isimportant toestablish soilstrengths andother engineer-ing properties. Ageotechnicalengineering con-

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Subsidence, slippage, andother kinds of slope failure

can damage structures.

Sinkholes, like this one that occurred just north of Orlando, Florida in 1981, are a risk ofdevelopment in Karst terrain. Left: aerial view (note baseball diamond for scale); right:

ground-level view. Photos courtesy of City of Winter Park, Florida public relations office.

sultant can accomplish this by performingstandard penetration tests, field vane sheartests, and laboratory tests. This informationwill determine how large a unit you can safelyplace on the site. Other soil properties toexamine include water content, shearstrength, plasticity, and grain size distribution.

Examine the liquefaction potential. It isextremely important to ascertain the liquefactionpotential of embankments, slopes, and founda-tion soils. Refer to Section C of this chapter formore information about liquefiable soils.

What can be done if aprospective site is in an unstable area?

It is advisable not to locate or expand yourwaste management unit in an unstable area. Ifyour unit is or will be located in such an area,you should safeguard the structural integrityof the unit by incorporating appropriate mea-sures into the design. The integrity of the unitmight be jeopardized if this is not done.

For example, to safeguard the structuralintegrity of side slopes in an unstable area,reduce slope height, flatten slope angle, exca-vate a bench in the upper portion of the slope,or buttress slopes with compacted earth or rockfill. Alternatively, build retaining structures,such as retaining walls or slabs and piles. Otherapproaches include the use of geotextiles andgeogrids to provide additional strength, wickand toe drains to relieve excess pore pressures,grouting, and vacuum and wellpoint pumpingto lower ground- water levels. In addition, sur-face drainage can be controlled to decreaseinfiltration, thereby reducing the potential formud and debris slides.

Additional engineering concerns arise inthe case of waste management units in areascontaining karst terrain. The principal con-cern with karst terrains is progressive or cata-strophic subsurface failure due to thepresence of sinkholes, solution cavities, and

subterranean caverns. Extensive subsurfacecharacterization studies should be completedbefore designing and building in these areas.Subsurface drilling, sinkhole monitoring, andgeophysical testing are direct means that canbe used to characterize a site. Geophysicaltechniques include electromagnetic conduc-tivity, seismic refraction, ground-penetratingradar, and electrical resistivity (see the boxbelow for more information). More than onetechnique should be used to confirm and cor-relate findings and anomalies, and a qualifiedgeophysicist should interpret the results ofthese investigations.

Remote sensing techniques, such as aerialphotograph interpretation, can also provideadditional information on karst terrains.Surface mapping can help provide an under-standing of structural patterns and relation-ships in karst terrains. An understanding oflocal carbonate geology and stratigraphy canhelp with the interpretation of both remotesensing and geophysical data.

You should incorporate adequate engineer-ing controls into any waste management unitlocated in a karst terrain. In areas where karstdevelopment is minor, loose soils overlyingthe limestone can be excavated or heavilycompacted to achieve the needed stability.Similarly, in areas where the karst voids arerelatively small, the voids can be filled withslurry cement grout or other material.

Engineering solutions can compensate forthe weak geologic structures by providingground supports. For example, ground modi-fications, such as grouting or reinforced raftfoundations, could compensate for a lack ofground strength in some karst areas. Raftconstructions, which are floating foundationsconsisting of a concrete footing extendingover a very large area, reduce and evenly dis-tribute waste loads where soils have a lowbearing capacity or where soil conditions arevariable and erratic. Note, however, that raftfoundations might not always prevent the


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extreme collapse and settlement that canoccur in karst areas. In addition, due to theunpredictable and catastrophic nature ofground failure in unstable areas, the con-struction of raft foundations and otherground modifications tends to be complexand can be costly, depending on the size ofthe area.

F. Airport VicinitiesThe vicinity of an airport includes not only

the facility itself, but also large reserved openareas beyond the ends of runways. If a unit isintended to be sited near an airport, there areparticular issues that take on added impor-tance in such areas. You should familiarizeyourself with Federal Aviation Administration(FAA) regulations and guidelines. The prima-ry concern associated with waste managementunits near airports is the hazard posed to air-craft by birds, which often feed at units man-aging putrescible waste. Planes can losepropulsion when birds are sucked into jetengines, and can sustain other damage in col-lisions with birds. Industrial waste manage-ment units that do not receive putresciblewastes should not have a problem with birds.Another area of concern for landfills andwaste piles near airports is the height of theaccumulated waste. If you own or operatesuch a unit, you should exercise cautionwhen managing waste above ground level.

How is it determined if aprospective site will be locatedtoo close to an airport?

If the prospective site is not located nearany airports, additional evaluation is not nec-essary. If there is uncertainty whether theprospective site is located near an airport,obtain local maps of the area using the variousInternet resources previously discussed orfrom state and local regulatory agencies toidentify any nearby public-use airports.

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Geophysical TechniquesElectromagnetic Conductivity or

Electromagnetic Induction (EMI). A transmittercoil generates an electromagnetic field whichinduces eddy currents in the earth located belowthe transmitter. These eddy currents create sec-ondary electromagnetic fields which are measuredby a receiver coil. The receiver coil produces an out-put voltage that can be related to subsurface con-ductivity variations. Analysis of these variationsallows users to map subsurface features, stratigraph-ic profiles, and the existence of buried objects.

Seismic Refraction. An artificial seismic source(e.g., hammer, explosives) creates compressionwaves that are refracted as they travel along geologicboundaries. These refracted waves are detected byelectromechanical transducers (geophones) whichare attached to a seismograph that records the timeof arrival of all waves (refracted and non-refracted).These travel times are compared and analyzed toidentify the number of stratigraphic layers and thedepth of each layer.

Ground-Penetrating Radar. A transmittingantenna dragged along the surface of the groundradiates short pulses of high-frequency radiowaves into the ground. Subsurface structuresreflect these waves which are recorded by areceiving antenna. The variations in reflectedreturn signals are used to generate an image ormap of the subsurface structure.

Electrical Resistivity. An electrical current isinjected into the ground by a pair of surface elec-trodes (called the current electrodes). By measuringthe resulting voltage (potential field) between a sec-ond pair of electrodes (called the potential elec-trodes), the resistivity of subsurface materials ismeasured. The measured resistivity is then com-pared to known values for different soil and rocktypes. Increasing the distance between the two pairsof electrodes increases the depth of measurement.

Topographic maps available from USGS arealso suitable for determining airport locations.If necessary, FAA can provide information onthe location of all public-use airports. In accor-dance with FAA guidance, if a new unit or anexpansion of an existing unit will be within 5miles of the end of a public-use airport run-way, the affected airport and the regional FAAoffice should be notified to provide them anopportunity for review and comment.

What can be done if aprospective site is in an airport vicinity?

If a proposed waste management unit or alateral expansion is to be located within10,000 feet of an airport used by jet aircraftor within 5,000 feet of an airport used onlyby piston-type aircraft, design and operateyour unit so it does not pose a bird hazard toaircraft. For above-ground units, design andoperate your unit so it does not interferewith flight patterns. If it appears that heightis a potential concern, consider entrenchingthe unit or choosing a site outside the air-port’s flight patterns. Most nonhazardousindustrial waste management units do notusually manage wastes that are attractivefood sources for birds, but if your unit han-dles waste that potentially attracts birds, takeprecautions to prevent birds from becomingan aircraft hazard. Discourage congregationof birds near your unit by preventing waterfrom collecting on site; eliminating or cover-ing wastes that might serve as a source offood; using visual deterrents, including real-istic models of the expected scavenger birds’natural predators; employing sound deter-rents, such as cannon sounds, distress callsof scavenger birds, or the sounds of thebirds’ natural predators; removing nestingand roosting areas (unless such removal isprohibited by the Endangered Species Act);or constructing physical barriers, such as acanopy of fine wires or nets strung around

the disposal and storage areas when practicalor technically feasible.

G. Wellhead ProtectionAreas

Wellhead protection involves protectingthe ground-water resources that supply pub-lic drinking water systems. A wellhead pro-tection area (WHPA) is the area mostsusceptible to contamination surrounding awellhead. WHPAs are designated and oftenregulated to prevent public drinking watersources from becoming contaminated. Thetechnical definition, delineation, and regula-tion of WHPAs vary from state to state. Youshould contact your state or local regulatoryagency to determine what wellhead protec-tion measures are in place near prospectivesites. Section II of this chapter providesexamples of how some states specify mini-mum allowable distances between wastemanagement units and public water supplies,as well as drinking water wells. Locating awaste management unit in a WHPA can cre-ate a potential avenue for drinking water con-tamination through accidental release ofleachate, contaminated runoff, or waste. Inaddition, some states might have additionalrestrictions for areas in designated “solesource aquifier” systems.

How is it determined if aprospective site is in a wellheadprotection area?

A list of state wellhead protection programcontacts is available on EPA’s Web site at<www.epa.gov/ogwdw/safewater/source/contacts.html>. Also, USGS, NRCS, localwater authorities, and universities can pro-vide maps and further expertise that can helpyou to identify WHPAs. If there is uncertaintyregarding the proximity of the prospectivesite to a WHPA, contact the appropriate stateor local regulatory agency.


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What can be done if aprospective site is in a wellheadprotection area?

If a new waste management unit or lateralexpansion will be located in a WHPA or sus-pected WHPA, consider design modificationsto help prevent any ground-water contami-nation. For waste management units placedin these areas, work with state regulatoryagencies to ensure that appropriate ground-water barriers are installed between the unitand the ground-water table. These barriersshould be designed using materials ofextremely low permeability, such asgeomembrane liners or low permeability soilliners. The purpose of such barriers is toprevent any waste, or leachate that has per-colated through the waste, from reaching theground water and possibly affecting the pub-lic drinking water source.

In addition to ground-water barriers, theuse of leachate collection, leak detection, andrunoff control systems should also be consid-ered. Leachate contamination is possibly thegreatest threat to a public ground-water sup-ply posed by a waste management unit.Incorporation of leachate collection, leakdetection, and runoff control systems shouldfurther prevent any leachate from escapinginto the ground water. Further discussionconcerning liner systems, leachate collectionand removal systems, and leak detection sys-tems is included in Chapter 7, SectionB–Designing and Installing Liners.

Control systems that separate storm-waterrun-on from any water that has contactedwaste should also be considered. Proper con-trol measures that redirect storm water to thesupply source area should help alleviate thistendency. For additional information con-cerning storm water run-on and runoff con-trol systems, refer to Chapter 6–ProtectingSurface Water.

II. Buffer ZoneConsiderations

Many states require buffer zones betweenwaste management units and other nearbyland uses, such as schools. The size of abuffer zone often depends on the type ofwaste management unit and the land use ofthe surrounding areas. You should consultwith state regulatory agencies and local advi-sory boards about buffer zone requirementsbefore constructing a new unit or expandingan existing unit. A summary of state bufferzone requirements is included in the appen-dix at the end of this chapter.

Buffer zones provide you with time andspace to mitigate situations where accidentalreleases might cause adverse human health orenvironmental impacts. The size of the bufferzone will be directly related to the intendedbenefit. These zones provide four primarybenefits:

• Maintenance of quality of the sur-rounding ground water.

• Prevention of contaminant migrationoff site.

• Protection of drinking water sup-plies.

• Minimization of nuisance conditionsperceived in surrounding areas.

Protection of ground water will likely bethe primary concern for all involved parties.You should ensure that materials processedand disposed at your unit are isolated fromground-water resources. Placing your unitfurther from the water table and potentialreceptors, and increasing the number ofphysical barriers between your unit and thewater table and potential receptors, providesfor ground-water protection. It is thereforeadvised that, in addition to incorporating aliner system, where necessary, into a waste

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management unit’s design, you select a sitewhere an adequate distance separates the bot-tom of a unit from the ground-water table.(See the appendix for a summary of theseminimum separation distances.)16 In the eventof a release, this separation distance willallow for corrective action and natural attenu-ation to protect ground water.17

Additionally, in the event of an unplannedrelease, an adequate buffer zone will allowtime for remediation activities to control con-taminants before they reach sensitive areas.Buffer zones also provide additional protec-tion for drinking water supplies. Drinkingwater supplies include ground water, individ-ual and community wells, lakes, reservoirs,and municipal water treatment facilities.

Finally, buffer zones help maintain goodrelations with the surrounding community by

protecting surrounding areas from any noise,particulate emissions, and odor associatedwith your unit. Buffer zones also help to pre-vent access by unauthorized people. For unitslocated near property boundaries, houses, orhistoric areas, trees or earthen berms can pro-vide a buffer to reduce noise and odors.Planting trees around a unit can also improvethe aesthetics of a unit, obstruct any view ofunsightly waste, and help protect propertyvalues in the surrounding community. Whenplanting trees as a buffer, place them so thattheir roots will not damage the unit’s liner orfinal cover.

A. Recommended BufferZones

You should check with state and local offi-cials to determine what buffer zones mightapply to your waste management unit. Areasfor which buffer zones are recommendedinclude property boundaries, drinking waterwells, other sources of water, and adjacenthouses or buildings.

Property boundaries. To minimizeadverse effects on adjacent properties, consid-er incorporating a buffer zone or separationdistance into unit design. You should consid-er planting trees or bushes to provide a nat-ural buffer between your unit and adjacentproperties.

Drinking water wells, surface-waterbodies, and public water supplies. Locatinga unit near or within the recharge area forsole source aquifers and major aquifers,coastal areas, surface-water bodies, or publicwater supplies, such as a community well orwater treatment facility, also raises concerns.Releases from a waste management unit canpose serious threats to human health not onlywhere water is used for drinking, but alsowhere surface waters are used for recreation.


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16 A detailed discussion of technical considerations concerning the design and installation of liner sys-tems, both in situ soil liners and synthetic liners, is included in Chapter 7, Section B – Designing andInstalling Liners.

17 Natural attenuation can be defined as chemical and biological processes that reduce contaminant con-centrations.

Many nearby areas and land uses, such asschools, call for consideration of buffer zones.

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18 For the full text of the Endangered Species Act, visit the U.S. House of Representatives Internet LawLibrary Web site at <uscode.house.gov/download.htm>, under Title 16, Chapter 35.


Houses or buildings. Waste managementunits can present noise, odor, and dust prob-lems for residents or businesses located onadjacent property, thereby diminishing prop-erty values. Additionally, proximity to proper-ty boundaries can invite increasedtrespassing, vandalism, and scavenging.

B. Additional Buffer ZonesThere are several other areas for which to

consider establishing buffer zones, includingcritical habitats, park lands, public roads, andhistoric or archaeological sites.

Critical habitats. These are geographicalareas occupied by endangered or threatenedspecies. These areas contain physical or bio-logical features essential to the proliferation ofthe species. When designing a unit near acritical habitat, it is imperative that the criti-cal habitat be conserved. A buffer zone canhelp prevent the destruction or adverse modi-fication of a critical habitat and minimizeharm to endangered or threatened species.18

Park lands. A buffer between your unitand park boundaries helps maintain the aes-thetics of the park land. Park lands providerecreational opportunities and a naturalrefuge for wildlife. Locating a unit too closeto these areas can disrupt recreational quali-ties and natural wildlife patterns.

Public roads. A buffer zone will helpreduce unauthorized access to the unit,reduce potential odor concerns, and improveaesthetics for travelers on the nearby road.

Historic or archaeological sites. A wastemanagement unit located in close proximityto one of these sites can adversely impact theaesthetic quality of the site. These areasinclude historic settlements, battlegrounds,cemeteries, and Indian burial grounds. Alsocheck whether a prospective site itself hashistorical or archaeological significance.

In summary, it is important to check withlocal authorities to ensure that placement ofa new waste management unit or lateralexpansion of an existing unit will not conflictwith any local buffer zone criteria. Youshould also review any relevant state or tribal

Buffer zones can help protect endangeredspecies and their habitats.

Historic sites call for careful considerationof buffer zones.

regulations that specify buffer zones for yourunit. For units located near any sensitiveareas as described in this section, considermeasures to minimize any possible health,environmental, and nuisance impacts.

III. Local Land Useand ZoningConsiderations

In addition to location and buffer zoneconsiderations, become familiar with anylocal land use and zoning requirements. Localgovernments often classify the land withintheir communities into areas, districts, orzones. These zones can represent differentuse categories, such as residential, commer-cial, industrial, or agricultural. You shouldconsider the compatibility of a planned newunit or a planned lateral expansion with near-by existing and future land use, and contactlocal authorities early in the siting process.Local planning, zoning, or public works offi-cials can discuss with you the development ofa unit, compliance with local regulations, andavailable options. Local authorities mightimpose conditions for protecting adjacentproperties from potential adverse impactsfrom the unit.

Addressing local land use and zoningissues during the siting process can preventthese issues from becoming prominent con-cerns later. Land use and zoning restrictionsoften address impacts on community andrecreational areas, historical areas, and othercritical areas. You should consider the prox-imity of a new unit or lateral expansion tosuch areas and evaluate any potential adverseeffects it might have on these areas. Forexample, noise, dust, fumes, and odors fromconstruction and operation of a unit could beconsidered a nuisance and legal action could

be brought by local authorities or nearbyproperty owners.

In situations where land use and zoningrestrictions might cause difficulties in expand-ing or siting a unit, work closely with localauthorities to learn about local land use andzoning restrictions and minimize potentialproblems. Misinterpreting or ignoring suchrestrictions can cause complications withintended development schedules or designs.In many cases, the use of vegetation, fences,or walls to screen your activities can reduceimpacts on nearby properties. In addition, itmight be possible to request amendments,rezonings, special exceptions, or variances torestrictions. These administrative mechanismsallow for flexibility in use and development ofland. Learning about local requirements asearly as possible in the process will maximizethe time available to apply for variances orrezoning permits, or to incorporate screeninginto the plans for your unit.

IV. EnvironmentalJusticeConsiderations

In the past several years, there has beengrowing recognition from communities andfederal and state governments that somesocioeconomic and racial groups might bear adisproportionate burden of adverse environ-mental effects from waste management activi-ties. President Clinton issued Executive Order12898, Federal Actions to AddressEnvironmental Justice in MinorityPopulations and Low-Income Populations, onFebruary 11, 1994.19 To be consistent withthe definition of environmental justice in thisexecutive order, you should identify andaddress, as appropriate, disproportionatelyhigh and adverse human health or environ-mental effects of waste management pro-


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19 For the full text of Presidential Executive Order No. 12898 and additional information concerningenvironmental justice issues go to EPA’s Web site at <es.epa.gov/program/iniative/justice/justice.html>.

grams, policies, and activities on minorityand low-income populations.

One of the criticisms made by advocates ofenvironmental justice is that local communi-ties endure the potential health and safetyrisks associated with waste managementunits without enjoying any of the economicbenefits. During unit siting or expansion,address environmental justice concerns in amanner that is most appropriate for the oper-ations, the community, and the state or tribalgovernment.

You should look for opportunities to mini-mize environmental impacts, improve thesurrounding environment, and pursueopportunities to make the waste management

facility an asset to the community. Whenplanning these opportunities, it is beneficialto maintain a relationship with all involvedparties based on honesty and integrity, utilizecross-cultural formats and exchanges, andrecognize industry, state, and local knowl-edge of the issues. It is also important to takeadvantage of all potential opportunities fordeveloping partnerships.

Examples of activities that incorporateenvironmental justice issues include tailoringactivities to specific needs; providing inter-preters, if appropriate; providing multilingualmaterials; and promoting the formation of acommunity/state advisory panel.

Tailor the public involvement activitiesto the specific needs. Good public involve-ment programs are site-specific—they takeinto account the needs of the facility, neigh-borhood, and state. There is no such thingas a “one-size-fits-all” public involvementprogram. Listening to each other carefullywill identify the specific environmental jus-tice concerns and determine the involve-ment activities most appropriate to addressthose needs.

Provide interpreters for public meetings.Interpreters can be used to ensure the infor-mation is exchanged. Provide interpreters, asneeded, for the hearing impaired and for anylanguages, other than English, spoken by asignificant percentage of the audience.

Provide multilingual fact sheets andother information. Public notices and factsheets should be distributed in as many lan-guages as necessary to ensure that all inter-ested parties receive necessary information.Fact sheets should be available for the visual-ly impaired in the community on tape, inlarge print, or braille.

Promote the formation of a community/state advisory panel to serve as the voice ofthe community. The Louisiana Departmentof Environmental Quality, for example,encourages the creation of environmental jus-tice panels comprised of community mem-bers, industry, and state representatives. Thepanels meet monthly to discuss environmen-tal justice issues and find solutions to anyconcerns identified by the group.

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General Siting Considerations■■■■ Check to see if the proposed unit site is:

— In a 100-year floodplain.

— In or near a wetland area.

— Within 200 feet of an active fault.

— In a seismic impact zone.

— In an unstable area.

— Close to an airport.

— Within a wellhead protection area.

■■■■ If the proposed unit site is in any of these areas:

— Design the unit to account for the area’s characteristics and minimize the unit’s impacts onsuch areas.

— Consider siting the unit elsewhere.

Buffer Zone Considerations(Note that many states require buffer zones between waste management units and other nearby land

uses.)

■■■■ Check to see if the proposed unit site is near:

— The ground-water table.

— A property boundary.

— A drinking water well.

— A public water supply, such as a community well, reservoir, or water treatment facility.

— A surface-water body, such as a lake, stream, river, or pond.

— Houses or other buildings.

— Critical habitats for endangered or threatened species.

— Park lands.

— A public road.

— Historic or archaeological sites.

■■■■ If the proposed unit site is near any of these areas or land uses, determine how large a buffer zone,if any, is appropriate between the unit and the area or land use.

Considering the Site Activity List

4-26


Local Land Use and Zoning Considerations■■■■ Contact local planning, zoning, and public works agencies to discuss restrictions that apply to the

unit.

■■■■ Comply with any applicable restrictions, or obtain the necessary variances or special exceptions.

Environmental Justice Considerations■■■■ Determine whether minority or low-income populations would bear a disproportionate burden of

any environmental effects of the unit’s waste management activities.

■■■■ Work with the local community to devise strategies to minimize any potentially disproportionateburdens.

Considering the Site Activity List (cont.)


4-27

Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills. John Wiley & Sons Inc.

Das, B. M. 1990. Principles of Geotechnical Engineering. 2nd ed. Boston: PWS-Kent Publishing Co.

Federal Emergency Management Agency. How to Read a Flood Insurance Map. Web Site:<www.fema.gov/nfip/readmap.htm>

Federal Emergency Management Agency. The National Flood Insurance Program Community Status Book.Web Site: <www.fema.gov/nfip/>

Federal Emergency Management Agency. 1995. The Zone A Manual: Managing Floodplain Development inApproximate Zone A Areas. FEMA 265.

Illinois Department of Energy and Natural Resources. 1990. Municipal Solid Waste Management Options:Volume II: Landfills.

Law, J., C. Leung, P. Mandeville, and A. H. Wu. 1996. A Case Study of Determining Liquefaction Potential ofa New Landfill Site in Virginia by Using Computer Modeling. Presented at WasteTech ’95, New Orleans, LA(January).

Noble, George. 1992. Siting Landfills and Other LULUs. Technomic Publications.

Oregon Department of Environmental Quality. 1996. Wellhead Protection Facts. Web Site:<www.deq.state.or.us/wq/groundwa/gwwell.htm>.

Terrene Institute.1996. American Wetlands: A Reason to Celebrate.

Texas Natural Resource Conservation Commission. 1983. Industrial Solid Waste Landfill Site Selection.

U.S. Army Corps of Engineers. 1995. Engineering and Design: Design and Construction of ConventionallyReinforced Ribbed Mat Slabs (RRMS). ETL 1110-3-471.

U.S. Army Corps of Engineers. 1995. Engineering and Design: Geomembranes for Waste ContainmentApplications. ETL 1110-1-172.

U.S. Army Corps of Engineers. 1992. Engineering and Design: Bearing Capacity of Soils. EM 1110-1-1905.

U.S. Army Corps of Engineers. 1992. Engineering and Design: Design and Construction of Grouted Riprap.ETL 1110-2-334.

Resources

4-28


U.S. Army Corps of Engineers. 1991. 1987 U.S. Army Corps of Engineers Wetlands Delineation Manual.HQUSACE.

U.S. Army Corps of Engineers. 1984. Engineering and Design: Use of Geotextiles Under Riprap. ETL1110-2-286.

U.S. EPA. 2000a. Social Aspects of Siting RCRA Hazardous Waste Facilities. EPA530-K-00-005.

U.S. EPA. 2000b. Siting of Hazardous Waste Management Facilities and Public Opposition. EPAOSW-0-00-809.

U.S. EPA. 1997. Sensitive Environments and the Siting of Hazardous Waste Management Facilities.EPA530-K-97-003.

U.S. EPA. 1995a. OSWER Environmental Justice Action Agenda. EPA540-R-95-023.

U.S. EPA. 1995b. Decision-Maker’s Guide to Solid Waste Management, 2nd Ed. EPA530-R-95-023.

U.S. EPA. 1995c. RCRA Subtitle D (258) Seismic Design Guidance for Municipal Solid Waste LandfillFacilities. EPA600-R-95-051.

U.S. EPA. 1995d. Why Do Wellhead Protection? Issues and Answers in Protecting Public Drinking WaterSupply Systems. EPA813-K-95-001.

U. S. EPA. 1994. Handbook: Ground Water and Wellhead Protection. EPA625-R-94-001.

U. S. EPA. 1993a. Guidelines for Delineation of Wellhead Protection Areas. EPA440-5-93-001.

U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.

U. S. EPA. 1992. Final Comprehensive State Ground-Water Protection Program Guidance. EPA100-R-93-001.

U. S. EPA. 1991. Protecting Local Ground-Water Supplies Through Wellhead Protection. EPA570-09-91-007.

U. S. EPA. 1988. Developing a State Wellhead Protection Program: A User’s Guide to Assist State AgenciesUnder the Safe Drinking Water Act. EPA440-6-88-003.

U.S. Geological Survey. Preliminary Young Fault Maps, Miscellaneous Field Investigation 916.

Resources (cont.)


4-29

U.S. Geological Survey. Probabilistic Acceleration and Velocity Maps for the United States and Puerto Rico.Map Series MF-2120.

U.S. House of Representatives. 1996. Endangered Species Act. Internet Law Library. Web Site:<uscode.house.gov/title_16.htm>.

University of Illinois Center for Solid Waste Management and Research, Office of Technology Transfer. 1990.Municipal solid waste landfills: Volume II: Technical issues.

University of Illinois Center for Solid Waste Management and Research, Office of Technology Transfer. 1989.Municipal Solid Waste Landfills: Vol. I: General Issues.

White House. Executive Order 12898 Federal Actions to Address Environmental Justice in MinorityPopulations and Low-Income Populations.

Resources (cont.)

The universe of industrial wastes and unit types is broad and diverse. States have establishedvarious approaches to address location considerations for the variety of wastes and units intheir states. The tables below summarize the range of buffer zone restrictions and most com-mon buffer zone values specified for each unit type by some states to address their local con-cerns. The numbers in the tables are not meant to advocate the adoption of a buffer zone ofany particular distance; rather, they serve only as examples of restrictions states have individu-ally developed.

• Surface impoundments. Restrictions with respect to buffer zones vary among states.In addition, states allow exemptions or variances to these buffer zone restrictions on acase-by-case basis. Table 1 presents the range of values and the most common valueused by states for each buffer zone category.

Table 1State Buffer Zone Restrictions for Surface Impoundments

Buffer Zone Category Range of Values—minimum Most Common Value (number of distance (number of states states with this common value)with this common value)

Groundwater Table 1 to 15 feet (4) 5 feet (2)

Property Boundaries 100 to 200 feet (4) 100 feet (2)

Drinking Water Wells 1,200 to 1,320 feet (2) 1,200 feet (1)1,320 feet (1)

Public Water Supply 500 to 1,320 feet (4) 1,320 feet (2)

Surface Water Body 100 to 1,320 feet (4) 100 feet (2)

Houses or Buildings 300 to 1,320 feet (4) 1,320 feet (2)

Roads 1,000 feet (1) 1,000 feet (1)

4-30


Appendix: State Buffer Zone Considerations


4-31

• Landfills. Table 2 presents the range of values and the most common state buffer zonerestrictions for landfills.

Table 2State Buffer Zone Restrictions for Landfills

Buffer Zone Category Range of Values—minimum Most Common Value (number of distance (number of states with states with this common value)this common value)

Groundwater Table 1 to 15 feet (12) 5 feet (4)


Drinking Water Wells 500 to 1,320 feet (9) 500 feet (2)600 feet (2)1,200 feet (2)

Public Water Supply 400 to 5,280 feet (13) 1,200 feet (3)

Surface Water Body 100 to 2,000 feet (20) 100 feet (5)1,000 feet (5)

Houses or Buildings 200 to 1,320 feet (14) 500 feet (7)

Roads 50 to 1,000 feet (8) 1,000 feet (5)

Park Land 1,000 to 5,280 feet (7) 1,000 feet (4)

Fault Areas 200 feet (2) 200 feet (2)

• Waste Piles. Table 3 presents the state buffer zone restrictions for waste piles. Of thefour states with buffer zone restrictions, only two states specified minimum distances.

Table 3State Buffer Zone Restrictions for Waste Piles

Buffer Zone Category Range of Values-minimum Most Common Value (number of distance (number of states states with this common value)with this common value)

Groundwater Table 4 feet* (1) 4 feet* (1)

Property Boundaries 50 feet (1) 50 feet (1)

Surface Water Body 50 feet (1) 50 feet (1)

Houses or Buildings or 200 feet (1) 200 feet (1)Recreational Area

Historic Archeological Site Minimum distance (1) Minimum distance (1)or Critical Habitat not specified not specified

* If no liner or storage pad is used, then this state requires four feet between the waste andthe seasonal high water table.

4-32



4-33

• Land Application.20 Table 4 presents the range of values and the most common statebuffer zone restrictions for land application.

Table 4State Buffer Zone Restrictions for Land Application

Buffer Zone Category Range of Values-minimum Most Common Value (number of distance (number of states with states with this common value)this common value)

Groundwater Table 4 to 5 feet (3) 4 feet (1)5 feet (1)


Drinking Water Wells 200 to 500 feet (2) 200 feet (1)500 feet (1)

Public Water Supply 300 to 5,280 feet (3) 300 feet (1)1,000 feet (1)5,280 feet (1)

Surface Water Body 100 to 1,000 feet (5) 100 feet (2)

Houses or Buildings 200 to 3,000 feet (6) 300 feet (2)500 feet (2)

Park Land 2,640 feet (1) 2,640 feet (1)

Fault Areas 200 feet (1) 200 feet (1)

Max. Depth of Treatment 5 feet (1) 5 feet (1)

Pipelines 25 feet (1) 25 feet (1)

Critical Habitat No minimum distance set (2) No minimum distance set (2)

Soil Conditions Not on frozen, ice or snow (1) Not on frozen, ice or snow (1)covered, or water saturated soils covered, or water saturated soils

20 In the review of state regulations performed to develop Table 5, it was not possible to distinguishbetween units used for treatment and units where wastes are added as a soil amendment. It is recom-mended that you consult applicable state agencies to determine which buffer zone restrictions are rele-vant to your land application unit.

Based on the review of state requirements, Table 5 presents the most common buffer zonesrestrictions across all four unit types.

Table 5Common Buffer Zone Restrictions Across All Four Unit Types

Buffer Zone Category Most Common Values(total number of states for all unit types) (number of states with this common value)

Groundwater Table (20) 4 feet (4)5 feet (4)

Property Boundaries (23) 50 feet (8)100 feet (5)

Drinking Water Wells (13) 500 feet (3)

Public Water Supply (20) 1,000 feet (3)1,200 feet (3)5,280 feet (3)

Surface Water Body (30) 100 feet (5)200 feet (5)1,000 feet (7)

Houses or Buildings (25) 500 feet (9)

4-34


Part II Protecting Air Quality

Chapter 5Protecting Air Quality

Contents

I. Federal Airborne Emission Control Programs ..........................................................................................5-3

A. National Ambient Air Quality Standards ..................................................................................................5-3

B. New Source Performance Standards ........................................................................................................5-3

C. National Emission Standards for Hazardous Air Pollutants ......................................................................5-4

D. Title V Operating Permits ......................................................................................................................5-10

E. Federal Airborne Emission Regulations for Solid Waste Management Activities ....................................5-10

1. Hazardous Waste Management Unit Airborne Emission Regulations ................................................5-10

2. Municipal Solid Waste Landfill Airborne Emission Regulations ........................................................5-10

3. Offsite Waste and Recovery Operations NESHAP ..............................................................................5-11

F. A Decision Guide to Applicable CAA Requirements ..............................................................................5-12

1. Determine Emissions from the Unit ..................................................................................................5-12

2. Is the Waste Management Unit Part of an Industrial Facility Which Is Subject to a CAATitle V Opening Permit? ....................................................................................................................5-14

3. Conduct a Risk Evaluation Using One of the Following Options:......................................................5-17

II. Assessing Risk ........................................................................................................................................5-17

A. Assessing Risks Associated with Inhalation of Ambient Air ..................................................................5-17

B. IWAIR Model ........................................................................................................................................5-21

1. Emissions Model................................................................................................................................5-21

2. Dispersion Model ..............................................................................................................................5-21

3. Risk Model ........................................................................................................................................5-23

4. Estimation Process ............................................................................................................................5-23

5. Capabilities and Limitations of the Model..........................................................................................5-27

C. Site-specific Risk Analysis ......................................................................................................................5-28

III. Emission Control Techniques..................................................................................................................5-32

A. Controlling Particulate Matter ................................................................................................................5-32

1. Vehicular Operations ........................................................................................................................5-32

2. Waste Placement and Handling ........................................................................................................5-33

3. Wind Erosion ....................................................................................................................................5-35

B. VOC Emission Control Techniques ........................................................................................................5-36

1. Choosing a Site to Minimize Airborne Emission Problems ................................................................5-36

2. Pretreatment of Waste ........................................................................................................................5-36

3. Enclosure of Units ............................................................................................................................5-36

4. Treatment of Captured VOCs ............................................................................................................5-37

5. Special Considerations for Land Application Units ............................................................................5-38

Protecting Air Activity List ............................................................................................................................5-39

Contents

Resources ......................................................................................................................................................5-40

Figures:

Figure 1. Evaluating VOC Emission Risk ..................................................................................................5-13

Figure 2. Conceptual Site Diagram ............................................................................................................5-18

Figure 3. Emissions from WMU ................................................................................................................5-19

Figure 4. Forces That Affect Contaminant Plumes......................................................................................5-20

Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations ................................5-24

Figure 6. Screen 1, Method, Met Station, WMU ........................................................................................5-25

Figure 7. Screen 2, Wastes Managed ..........................................................................................................5-25

Tables:

Table 1. Industries for Which NSPSs Have Been Established ......................................................................5-5

Table 2. HAPs Defined in Section 112 of the CAA Amendments of 1990 ....................................................5-6

Table 3. Source Categories With MACT Standards ......................................................................................5-8

Table 4. Major Source Determination in Nonattainment Areas ..................................................................5-15

Table 5. Constituents Included in IWAIR ..................................................................................................5-22

Table 6. Source Characterization Models....................................................................................................5-29

Table 7. Example List of Chemical Suppressants ........................................................................................5-34

Protecting Air Quality—Protecting Air Quality

5-1

Health effects from airborne pol-lutants can be minor andreversible (such as eye irrita-tion), debilitating (such asasthma), or chronic and poten-

tially fatal (such as cancer). Potential healthimpacts depend on many factors, includingthe quantity of air pollution to which peopleare exposed, the duration of exposures, andthe toxicity associated with specific pollu-tants. An air risk assessment takes these fac-tors into account to predict the risk orhazards posed at a particular site or facility.

Air releases from waste management unitsinclude particulates or wind-blown dust andgaseous emissions from volatile compounds

It is recommended that every facilityimplement controls to address emissions ofairborne particulates. Particulates have imme-diate and highly visible impacts on surround-ing neighborhoods. They can affect humanhealth and can carry constituents off site aswell. Generally, controls are achieved throughgood operating practices.

For air releases from industrial waste man-agement units, you need to know what regula-tory requirements under the Clean Air Act(CAA) apply to your facility, and whether thoserequirements address waste management units.The followup question for facilities whosewaste management units are not addressed byCAA requirements, is “are there risks from airreleases that should be controlled?”

This Guide provides two tools to help youanswer these questions. First, this chapterincludes an overview of the major emissioncontrol requirements under the CAA and adecision guide to evaluate which of these

Protecting Air QualityThis chapter will help you address:

• Airborne particulates and air emissions that can cause human health

risks and damage the environment by adopting controls to minimize

particulate emissions.

• Assessing risks associated with air emissions and implementing pol-

lution prevention, treatment, or controls as needed to reduce risks

for a facility’s waste management units not addressed by require-

ments under the Clean Air Act.

• Using a Clean Air Act Title V permit, at facilities that must obtain

one, as a vehicle for addressing air emissions from certain waste

management units.

This chapter will help you address the fol-lowing questions.

• Is a particular facility subject to CAArequirements?

• What is an air risk assessment?

• Do waste management units pose risksfrom volatile air emissions?

• What controls will reduce particulateand volatile emissions from a facility?

5-2


might apply to a facility. The steps of the deci-sion guide are summarized in Figure 1. Eachfacility subject to any of these requirementswill most likely be required to obtain a CAATitle V operating permit. The decision guidewill help you clarify some of the key facilityinformation you need to identify applicableCAA requirements.

If your answers in the decision guide indi-cate that the facility is or might be subject tospecific regulatory obligations, the next step isto consult with EPA, state, or local air qualityprogram staff. Some CAA regulations areindustry-specific and operation-specific withinan industry, while others are pollutant specificor specific to a geographic area. EPA, state, orlocal air quality managers can help you pre-cisely determine applicable requirements andwhether waste management units areaddressed by those requirements.

You might find that waste managementunits are not addressed or that a specific facili-ty clearly does not fit into any regulatory cate-gory under the CAA. It is then prudent tolook beyond immediate permit requirementsto assess risks associated with volatile organiccompounds (VOCs) released from the unit. A

two-tiered approach to this assessment is rec-ommended, depending on the complexity andamount of site specific data you have.

Limited Site-Specific Air Assessment:The CD-ROM version of the Guide containsthe Industrial Waste Air Model (IWAIR). If awaste contains any of the 95 constituentsincluded in the model, you can use this riskmodel to assess whether VOC emissions posea risk that warrants additional emission con-trols or that could be addressed more effec-tively with pollution prevention or wastetreatment before placement in the waste man-agement unit. The IWAIR model allows usersto supply inputs for an emission estimate andfor a dispersion factor for the unit.

Comprehensive Risk Assessment: Thisassessment relies on a comprehensive analysisof waste and site-specific data and use of mod-els designed to assess multi-pathway exposuresto airborne contaminants. There are a numberof modeling tools available for this analysis.You should consult closely with your air quali-ty management agency as you proceed.

Airborne emissions are responsible for the loss of visibility between the left and right pho-

tographs of the Grand Canyon. Source: National Park Service, Air Resources Division.


5-3

1 42 U.S.C. § 7409

2 For a discussion of the history of the litigation over the revised ozone standard and EPA’s plan forimplementing it, including possible revisions to 40 CFR 50.9(b), see 67 FR 48896 (July 26, 2002).

I. Federal AirborneEmission ControlPrograms

Four major federal programs address air-borne emissions that can degrade air quality.For more information about the CAA andEPA’s implementation of it, visit theTechnology Transfer Network, EPA’s premiertechnical Web site for information transferand sharing related to air pollution topics, at<www.epa.gov/ttn>.

If the facility is a major source or other-wise subject to Title V of the CAA, the ownermust obtain a Title V operating permit. Thesepermits are typically issued by the state airpermitting authority. As part of the permittingprocess, you will be required to develop anemissions inventory for the facility. Somestates have additional permitting require-ments. Whether or not emissions from awaste management unit will be specificallyaddressed through the permit processdepends on a number of factors, includingthe type of facility and state permittingresources and priorities. It is prudent, howev-er, where there are no applicable air permitrequirements to assess whether there mightbe risks associated with waste managementunits and to address these risks.

A. National Ambient AirQuality Standards

The CAA authorizes EPA to establish emis-sion limits to achieve National Ambient AirQuality Standards (NAAQS).1 EPA has desig-nated NAAQS for the following criteria pollu-tants: ozone, sulfur dioxide, nitrogen dioxide,lead, particulate matter (PM), and carbonmonoxide. The NAAQS establish individualpollutant concentration ceilings that should

be rarely exceeded in a predetermined geo-graphical area (National Ambient Air QualityDistrict). NAAQS are not enforced directly byEPA. Instead, each state must submit a StateImplementation Plan (SIP) describing how itwill achieve or maintain NAAQS. Many SIPscall for airborne emission limits on industrialfacilities.

If a waste emits VOCs, some of which areprecursors to ozone, the waste managementunit could be affected by EPA’s NAAQS forground-level ozone. Currently, states areimplementing an ozone standard of 0.12parts per million (ppm) as measured over a1-hour period. In 1997, EPA promulgated arevised standard of 0.08 ppm with an 8-houraveraging time to protect public health andthe environment over longer exposure peri-ods2 (see 62 FR 38856, July 18, 1997). EPA iscurrently developing regulations and guid-ance for implementing the 8-hour ozonestandard. EPA expects to designate areas asattaining or not attaining the standard in2004. At that time, areas not attaining thestandard will need to develop plans to controlemissions and to demonstrate how they willreach attainment. Consult with your state todetermine whether efforts to comply with theozone NAAQS involve VOC emission limitsthat apply to a specific facility. General ques-tions about the 8-hour standard should bedirected to EPA’s Office of Air QualityPlanning and Standards, Air QualityStrategies and Standards Division, OzonePolicy and Strategies Group, MD-15,Research Triangle Park, NC 27711, telephone919 541-5244.

B. New SourcePerformance Standards

New Source Performance Standards(NSPSs) are issued for categories of sourcesthat cause or contribute significant air pollu-

5-4


tion that can reasonably be anticipated toendanger public health or welfare. For indus-try categories, NSPSs establish national tech-nology-based emission limits for air pollutants,such as particulate matter (PM) or VOCs.States have primary responsibility for assuringthat the NSPSs are followed. These standardsare distinct from NAAQS because they estab-lish direct national emission limits for speci-fied sources, while NAAQS establish airquality targets that states meet using a varietyof measures that include emission limits. Table1 lists industries for which NSPSs have beenestablished and locations of the NSPSs in theCode of Federal Regulations. You shouldcheck to see if any of the 74 New SourcePerformance Standards (NSPSs)3 apply to thefacility.4 Any facility subject to a NSPS mustobtain a Title V permit (see Section D below.).

C. National EmissionStandards for HazardousAir Pollutants

Section 112 of the CAA Amendments of19905 requires EPA to establish national stan-dards to reduce emissions from a set of certainpollutants called hazardous air pollutants(HAPs). Section 112(b) contains a list of 188HAPs (see Table 2) to be regulated by NationalEmission Standards for Hazardous AirPollutants (NESHAPs) referred to as MaximumAchievable Control Technology (MACT) stan-dards, that are generally set on an industry-by-industry basis.

MACT standards typically apply to majorsources in specified industries; however, insome instances, non-major sources also can besubject to MACT standards. A major source isdefined as any stationary source or group ofstationary sources that (1) is located within acontiguous area and under common control,and (2) emits or has the potential to emit at

least 10 tons per year (tpy) of any single HAPor at least 25 tpy of any combination of HAPs.All fugitive emissions of HAPs, including emis-sions from waste management units, are to betaken into account in determining whether astationary source is a major source. EachMACT standard might limit specific opera-tions, processes, or wastes that are covered.Some MACT standards specifically cover wastemanagement units, while others do not. If afacility is covered by a MACT standard, itmust be permitted under Title V (see below).

EPA has identified approximately 170 indus-trial categories and subcategories that are or willbe subject to MACT standards. Table 3 lists thecategories for which standards have been final-ized, proposed, or are expected. The CAA callsfor EPA to promulgate the standards in fourphases. EPA is currently in the fourth and finalphase of developing proposed regulations.

CAA also requires EPA to assess the risk topublic health remaining after the implementa-tion of NESHAPs and MACT standards. EPAmust determine if more stringent standards arenecessary to protect public health with anample margin of safety or to prevent anadverse environmental effect. As a first step inthis process the CAA requires EPA to submit aReport to Congress on its methods for makingthe health risks from residual emissions deter-mination. The final report, Residual RiskReport to Congress (U.S. EPA, 1997b), wassigned on March 3, 1999 and is available fromEPA’s Web site at <www.epa.gov/ttn/oarpg/t3/reports/risk_rep.pdf>. If significant resid-ual risk exists after application of a MACT,EPA must promulgate health-based standardsfor that source category to further reduce HAPemissions. EPA must set residual risk stan-dards within 8 years after promulgation ofeach NESHAP.

3 40 CFR Part 60.

4 While NSPSs apply to new facilities, EPA also established emission guidelines for existing facilities.

5 42 U.S.C. § 7412.


5-5

Facility 40 CFR Part60 subpart

Ammonium Sulfate Manufacture PP

Asphalt Processing & Asphalt Roofing Manufacture UU

Auto/ld Truck Surface Coating Operations MM

Basic Oxygen Process Furnaces after 6/11/73 N

Beverage Can Surface Coating Industry WW

Bulk Gasoline Terminals XX

Calciners and Dryers in Mineral Industry UUU

Coal Preparation Plants Y

Commercial & Industrial SW Incinerator Units CCCC

Electric Utility Steam Generating Units after 9/18/78 DA

Equipment Leaks of VOC in Petroleum Refineries GGG

Equipment Leaks of VOC in SOCMI VV

Ferroalloy Production Facilities Z

Flexible Vinyl & Urethane Coating & Printing FFF

Fossil-fuel Fired Steam Generators after 8/17/71 D

Glass Manufacturing Plants CC

Grain Elevators DD

Graphic Arts: Publication Rotogravure Printing QQ

Hot Mix Asphalt Facilities I

Incinerators E

Industrial Surface Coating, Plastic Parts TTT

Industrial Surface Coating-Large Appliances SS

Industrial-Commercial-Institutional Steam Generation Unit DB

Kraft Pulp Mills BB

Large Municipal Waste Combustors after 9/20/94 EB

Lead-Acid Battery Manufacturing Plants KK

Lime Manufacturing HH

Magnetic Tape Coating Facilities SSS

Medical Waste Incinerators (MWI) after 6/20/96 EC

Metal Coil Surface Coating TT

Metallic Mineral Processing Plants LL

Municipal Solid Waste Landfills after 5/30/91 WWW

Municipal Waste Combustors (MWC) EA

New Residential Wood Heaters AAA

Nitric Acid Plants G

Nonmetallic Mineral Processing Plants OOO

Onshore Natural Gas Processing Plants, VOC Leaks KKK

Onshore Natural Gas Processing: SO2 Emissions LLL

Facility 40 CFR Part60 subpart

Petroleum Dry Cleaners, Rated Capacity 84 Lb JJJ

Petroleum Refineries J

Petroleum Refinery Wastewater Systems QQQ

Phosphate Fertilizer-Wet Process Phosphoric Acid T

Phosphate Fertilizer-Superphosphoric Acid U

Phosphate Fertilizer-Diammonium Phosphate V

Phosphate Fertilizer-Triple Superphosphate W

Phosphate Fertilizers: GTSP Storage Facilities X

Phosphate Rock Plants NN

Polymer Manufacturing Industry DDD

Polymeric Coating of Supporting Substrates Fac. VVV

Portland Cement Plants F

Pressure Sensitive Tape & Label Surface Coating RR

Primary Aluminum Reduction Plants S

Primary Copper Smelters P

Primary Lead Smelters R

Primary Zinc Smelters Q

Rubber Tire Manufacturing Industry BBB

Secondary Brass and Bronze Production Plants M

Secondary Lead Smelters L

Sewage Treatment Plants O

Small Indust./Comm./Institut. Steam Generating Units DC

Small Municipal Waste Combustion Units AAAA

SOCMI - Air Oxidation Processes III

SOCMI - Distillation Operations NNN

SOCMI Reactors RRR

SOCMI Wastewater YYY

Stationary Gas Turbines GG

Steel Plants: Elec. Arc Furnaces after 08/17/83 AAA

Steel Plants: Electric Arc Furnaces AA

Storage Vessels for Petroleum Liquids (6/73–5/78) K

Storage Vessels for Petroleum Liquids (5/78–6/84) KA

Sulfuric Acid Plants H

Surface Coating of Metal Furniture EE

Synthetic Fiber Production Facilities HHH

Volatile Storage Vessel (Incl. Petroleum) after 7/23/84 KB

Wool Fiberglass Insulation Manufacturing Plants PPP

Table 1. Industries for Which NSPSs Have Been Established

For electronic versions of the 40 CFR Part 60 subparts referenced below, visit

<www.access.gpo.gov/nara/cfr>. Be sure to check the Federal Register for updates that have

been published since publication of this Guide.

CAS# CHEMICAL NAME CAS# CHEMICAL NAME CAS# CHEMICAL NAME

75-07-0 Acetaldehyde

60-35-5 Acetamide

75-05-8 Acetonitrile

98-86-2 Acetophenone

53-96-3 2-Acetylaminofluorene

107-02-8 Acrolein

79-06-1 Acrylamide

79-10-7 Acrylic acid

107-13-1 Acrylonitrile

107-05-1 Allyl chloride

92-67-1 4-Aminobiphenyl

62-53-3 Aniline

90-04-0 o-Anisidine

1332-21-4 Asbestos

71-43-2 Benzene (including benzenefrom gasoline)

92-87-5 Benzidine

98-07-7 Benzotrichloride

100-44-7 Benzyl chloride

92-52-4 Biphenyl

117-81-7 Bis(2-ethylhexyl) phthalate(DEHP)

542-88-1 Bis(chloromethyl)ether

75-25-2 Bromoform

106-99-0 1,3-Butadiene

156-62-7 Calcium cyanamide

133-06-2 Captan

63-25-2 Carbaryl

75-15-0 Carbon disulfide

56-23-5 Carbon tetrachloride

463-58-1 Carbonyl sulfide

120-80-9 Catechol

133-90-4 Chloramben

57-74-9 Chlordane

7782-50-5 Chlorine

79-11-8 Chloroacetic acid

532-27-4 2-Chloroacetophenone

108-90-7 Chlorobenzene

510-15-6 Chlorobenzilate

67-66-3 Chloroform

107-30-2 Chloromethyl methyl ether

126-99-8 Chloroprene

1319-77-3 Cresols/Cresylic acid (isomersand mixture)

95-48-7 o-Cresol

108-39-4 m-Cresol

106-44-5 p-Cresol

98-82-8 Cumene

94-75-7 2,4-D, salts and esters

72-55-9 DDE

334-88-3 Diazomethane

132-64-9 Dibenzofurans

96-12-8 1,2-Dibromo-3-chloropropane

84-74-2 Dibutylphthalate

106-46-7 1,4-Dichlorobenzene(p)

91-94-1 3,3-Dichlorobenzidene

111-44-4 Dichloroethyl ether (Bis(2-chloroethyl)ether)

542-75-6 1,3-Dichloropropene

62-73-7 Dichlorvos

111-42-2 Diethanolamine

121-69-7 N,N-Diethyl aniline (N,N-Dimethylaniline)

64-67-5 Diethyl sulfate

119-90-4 3,3-Dimethoxybenzidine

60-11-7 Dimethyl aminoazobenzene

119-93-7 3,3’-Dimethyl benzidine

79-44-7 Dimethyl carbamoyl chloride

68-12-2 Dimethyl formamide

57-14-7 1,1-Dimethyl hydrazine

131-11-3 Dimethyl phthalate

77-78-1 Dimethyl sulfate

534-52-1 4,6-Dinitro-o-cresol, and salts

51-28-5 2,4-Dinitrophenol

121-14-2 2,4-Dinitrotoluene

123-91-1 1,4-Dioxane (1,4-Diethyleneoxide)

122-66-7 1,2-Diphenylhydrazine

106-89-8 Epichlorohydrin (l-Chloro- 2,3-epoxypropane)

106-88-7 1,2-Epoxybutane

140-88-5 Ethyl acrylate

100-41-4 Ethyl benzene

51-79-6 Ethyl carbamate (Urethane)

75-00-3 Ethyl chloride (Chloroethane)

106-93-4 Ethylene dibromide(Dibromoethane)

107-06-2 Ethylene dichloride (1,2-Dichloroethane)

107-21-1 Ethylene glycol

151-56-4 Ethylene imine (Aziridine)

75-21-8 Ethylene oxide

96-45-7 Ethylene thiourea

75-34-3 Ethylidene dichloride (1,1-Dichloroethane)

50-00-0 Formaldehyde

76-44-8 Heptachlor

118-74-1 Hexachlorobenzene

87-68-3 Hexachlorobutadiene

77-47-4 Hexachlorocyclopenta-diene

67-72-1 Hexachloroethane

822-06-0 Hexamethylene-1,6-diisocyanate

680-31-9 Hexamethylphosphor-amide

110-54-3 Hexane

302-01-2 Hydrazine

7647-01-0 Hydrochloric acid

7664-39-3 Hydrogen fluoride(Hydrofluoric acid)

123-31-9 Hydroquinone

78-59-1 Isophorone

58-89-9 Lindane (all isomers)

108-31-6 Maleic anhydride

67-56-1 Methanol

72-43-5 Methoxychlor

74-83-9 Methyl bromide(Bromomethane)

74-87-3 Methyl chloride(Chloromethane)

71-55-6 Methyl chloroform (1,1,1-Trichloroethane)

78-93-3 Methyl ethyl ketone (2-Butanone)

60-34-4 Methyl hydrazine

74-88-4 Methyl iodide (Iodomethane)

108-10-1 Methyl isobutyl ketone(Hexone)

624-83-9 Methyl isocyanate

80-62-6 Methyl methacrylate

1634-04-4 Methyl tert butyl ether

101-14-4 4,4-Methylene bis(2-chloroani-line)

75-09-2 Methylene chloride(Dichloromethane)

101-68-8 Methylene diphenyl diiso-cyanate (MDI)

101779 4,4’-Methylenedianiline

91-20-3 Naphthalene

98-95-3 Nitrobenzene

92-93-3 4-Nitrobiphenyl

100-02-7 4-Nitrophenol

79-46-9 2-Nitropropane

684-93-5 N-Nitroso-N-methylurea

62-75-9 N-Nitrosodimethylamine

59-89-2 N-Nitrosomorpholine

56-38-2 Parathion

82-68-8 Pentachloronitrobenzene(Quintobenzene)

87-86-5 Pentachlorophenol

108-95-2 Phenol

106-50-3 p-Phenylenediamine

75-44-5 Phosgene

7803-51-2 Phosphine


5-6

Table 2

HAPs Defined in Section 112 of the CAA Amendments of 1990


5-7

CAS# CHEMICAL NAME CAS# CHEMICAL NAME CAS# CHEMICAL NAME

Table 2

HAPs Defined in Section 112 of the CAA Amendments of 1990 (cont)

7723-14-0 Phosphorus

85-44-9 Phthalic anhydride

1336-36-3 Polychlorinated biphenyls(Aroclors)

1120-71-4 1,3-Propane sultone

57-57-8 beta-Propiolactone

123-38-6 Propionaldehyde

114-26-1 Propoxur (Baygon)

78-87-5 Propylene dichloride (1,2-Dichloropropane)

75-56-9 Propylene oxide

75-55-8 1,2-Propylenimine (2-Methylaziridine)

91-22-5 Quinoline

106-51-4 Quinone (p-Benzoquinone)

100-42-5 Styrene

96-09-3 Styrene oxide

1746-01-6 2,3,7,8-Tetrachlorodi-benzo-p-dioxin

79-34-5 1,1,2,2-Tetrachloroethane

127-18-4 Tetrachloroethylene(Perchloroethylene)

7550-45-0 Titanium tetrachloride

108-88-3 Toluene

95-80-7 2,4-Toluene diamine

584-84-9 2,4-Toluene diisocyanate

95-53-4 o-Toluidine

8001-35-2 Toxaphene (chlorinated cam-phene)

120-82-1 1,2,4-Trichlorobenzene

79-00-5 1,1,2-Trichloroethane

79-01-6 Trichloroethylene

95-95-4 2,4,5-Trichlorophenol

88-06-2 2,4,6-Trichlorophenol

121-44-8 Triethylamine

1582-09-8 Trifluralin

540-84-1 2,2,4-Trimethylpentane

108-05-4 Vinyl acetate

593-60-2 Vinyl bromide

75-01-4 Vinyl chloride

75-35-4 Vinylidene chloride (1,1-Dichloroethylene)

1330-20-7 Xylenes (mixed isomers)

95-47-6 o-Xylenes

108-38-3 m-Xylenes

106-42-3 p-Xylenes

[none] Antimony Compounds

[none] Arsenic Compounds (inorganicincluding arsine)

[none] Beryllium Compounds

[none] Cadmium Compounds

[none] Chromium Compounds

[none] Cobalt Compounds

[none] Coke Oven Emissions

[none] Cyanide Compoundsa

[none] Glycol ethersb

[none] Lead Compounds

[none] Manganese Compounds

[none] Mercury Compounds

[none] Fine mineral fibersc

[none] Nickel Compounds

[none] Polycylic Organic Matterd

[none] Radionuclides (includingradon)e

[none] Selenium Compounds

NOTE: For all listings above which contain the word “compounds” and for glycol ethers, the following applies: Unless otherwise specified,these listings are defined as including any unique chemical substance that contains the named chemical (i.e., antimony, arsenic, etc.) as partof that chemical’s infrastructure.

a X’CN where X = H’ or any other group where a formal dissociation can occur. For example KCN or Ca(CN)2.

b On January 12, 1999 (64 FR 1780), EPA proposed to modify the definition of glycol ethers to exclude surfactant alcohol ethoxylates andtheir derivatives (SAED). On August 2, 2000 (65 FR 47342), EPA published the final action. This action deletes each individual com-pound in a group called the surfactant alcohol ethoxylates and their derivatives (SAED) from the glycol ethers category in the list of haz-ardous air pollutants (HAP) established by section 112(b)(1) of the Clean Air Act (CAA). EPA also made conforming changes in thedefinition of glycol ethers with respect to the designation of hazardous substances under the Comprehensive Environmental Response,Compensation, and Liability Act (CERCLA).“The following definition of the glycol ethers category of hazardous air pollutants applies instead of the definition set forth in 42 U.S.C.7412(b)(1), footnote 2: Glycol ethers include mono- and di-ethers of ethylene glycol, diethylene glycol, and triethylene glycol R-(OCH2CH2)n-OR’Where:n= 1, 2, or 3R= alkyl C7 or less, or phenyl or alkyl substituted phenylR’= H, or alkyl C7 or less, or carboxylic acid ester, sulfate, phosphate, nitrate, or sulfonate.

c Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or slag fibers (or other mineral derived fibers) ofaverage diameter 1 micrometer or less. (Currently under review.)

d Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100°C.(Currently under review.)

e A type of atom which spontaneously undergoes radioactive decay.


5-8

Source Category Federal Register Citation

Fuel Combustion

Coal- and Oil-fired Electric Utility Steam Generating Units 65 FR 79825(N) 12/20/00

Combustion Turbines *

Engine Test Facilities *

Industrial Boilers *

Institutional/Commercial Boilers *

Process Heaters *

Reciprocating Internal Combustion Engines*

Rocket Testing Facilities *

Non-Ferrous Metals Processing

Primary Aluminum Production 62 FR 52383(F) 10/7/97

Primary Copper Smelting 63 FR 19582(P) 4/20/98

Primary Lead Smelting 64 FR 30194(F) 6/4/99

Primary Magnesium Refining *

Secondary Aluminum Production 65 FR 15689(F) 3/23/00

Secondary Lead Smelting 60 FR 32587(F) 6/23/95

Ferrous Metals Processing

Coke Ovens: Charging, Top Side, and Door Leaks 58 FR 57898(F) 10/27/93

Coke Ovens: Pushing, Quenching and Battery Stacks 66 FR 35327(P) 7/3/01

Ferroalloys Production

Silicomanganese and Ferromanganese 64 FR 27450(F) 5/20/00

Integrated Iron and Steel Manufacturing 66 FR 36835(P) 7/13/01

Iron Foundries *

Steel Foundries *

Steel Pickling–HCl Process Facilities and Hydrochloric Acid Regeneration Plants 64 FR 33202(F) 6/22/99

Mineral Products Processing

Asphalt Processing *

Asphalt Roofing Manufacturing *

Asphalt/Coal Tar Application–Metal Pipes *

Clay Products Manufacturing *

Lime Manufacturing *

Mineral Wool Production. 64 FR 29490(F) 6/1/99

Portland Cement Manufacturing 64 FR 31897(F) 6/14/99

Refractories Manufacturing *

Taconite Iron Ore Processing *

Wool Fiberglass Manufacturing 64 FR 31695(F) 6/14/99

Petroleum and Natural Gas Production and Refining

Oil and Natural Gas Production 64 FR 32610(F) 6/17/99

Natural Gas Transmission and Storage 64 FR 32610(F) 6/17/99

Petroleum Refineries–Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units 63 FR 48890(P) 9/11/98

Petroleum Refineries–Other Sources Not Distinctly Listed 60 FR 43244(F) 8/18/95

Liquids Distribution

Gasoline Distribution (Stage 1) 59 FR 64303(F) 12/14/94


Marine Vessel Loading Operations 60 FR 48399(F) 9/19/95

Organic Liquids Distribution (Non-Gasoline) *

Surface Coating Processes

Aerospace Industries 60 FR 45956(F) 9/1/15

Auto and Light Duty Truck *

Flat Wood Paneling 64 FR 63025(N) 11/18/99

Large Appliance 65 FR 81134(P) 12/22/00

Magnetic Tapes 59 FR 64580(F) 12/15/94

Manufacture of Paints, Coatings, and Adhesives *

Metal Can *

Metal Coil 65 FR 44616(P) 7/18/00

Metal Furniture *

Miscellaneous Metal Parts and Products *

Paper and Other Webs 65 FR 55332(P) 9/13/00

Plastic Parts and Products *

Printing, Coating, and Dyeing of Fabrics *

Printing/Publishing 61 FR 27132(F) 5/30/96

Shipbuilding and Ship Repair 60 FR 64330(F) 12/16/96

Wood Building Products *

Wood Furniture 60 FR 62930(F) 12/7/95

Waste Treatment and Disposal

Hazardous Waste Incineration 64 FR 52828(F) 9/30/99

Municipal Solid Waste Landfills 65 FR 66672(P) 11/7/00

Off-Site Waste and Recovery Operations 61 FR 34140(F) 7/1/96

Publicly Owned Treatment Works 64 FR 57572(F) 10/26/99

Site Remediation *

Agricultural Chemicals Production

Pesticide Active Ingredient Production 64 FR 33549(F) 6/23/99

Fibers Production Processes

Acrylic Fibers/Modacrylic Fibers 64 FR 34853(F) 6/30/99

Spandex Production 65 FR 76408(P) 12/6/00

Food and Agriculture Processes

Manufacturing of Nutritional Yeast 66 FR 27876(F) 5/21/01

Solvent Extraction for Vegetable Oil Production 66 FR 19006(F) 4/12/01

Vegetable Oil Production 66 FR 8220(N) 1/30/01

Pharmaceutical Production Processes

Pharmaceuticals Production 66 FR 40121(F) 6/1/99

Polymers and Resins Production

Acetal Resins Production 64 FR 34853(F) 6/30/99

Acrylonitrile-Butadiene-Styrene Production 61 FR 48208(F) 9/12/96

Alkyd Resins Production *

Amino Resins Production 65 FR 3275(F) 1/20/00

Boat Manufacturing 66 FR 44218(F) 8/22/01

Butyl Rubber Production 61 FR 46906(F) 9/5/96

Cellulose Ethers Production 65 FR 52166(P) 8/28/00

Epichlorohydrin Elastomers Production 61 FR 46906(F) 9/5/96

Table 3

Source Categories With MACT Standards


5-9

This table contains final rules (F), proposed rules (P), and notices (N) promulgated as of February 2002. It doesnot identify corrections or clarifications to rules. An * denotes sources required by Section 112 of the CAA to haveMACT standards by 11/15/00 for which proposed rules are being prepared but have not yet been published.

Table 3

Source Categories With MACT Standards (cont.)


Epoxy Resins Production 60 FR 12670(F) 3/8/95

Ethylene-Propylene Rubber Production 61 FR 46906(F) 9/5/96

Flexible Polyurethane Foam Production 63 FR 53980(F) 10/7/98

Hypalon (tm) Production 61 FR 46906(F) 9/5/96

Maleic Anhydride Copolymers Production *

Methyl Methacrylate-Acrylonitrile Butadiene-Styrene Production 61 FR 48208(F) 9/12/96

Methyl Methacrylate-Butadiene-Styrene Terpolymers Production 61 FR 48208(F) 9/12/96

Neoprene Production 61 FR 46906(F) 9/5/96

Nitrile Butadiene Rubber Production 61 FR 46906(F) 9/5/96

Nitrile Resins Production 61 FR 48208(F) 9/12/96

Non-Nylon Polyamides Production 60 FR 12670(F) 3/8/95

Phenolic Resins Production 65 FR 3275(F) 1/20/00

Polybutadiene Rubber Production 61 FR 46906(F) 9/5/96

Polycarbonates Production 64 FR 34853(F) 6/30/99

Polyester Resins Production *

Polyether Polyols Production 64 FR 29420(F) 6/1/99

Polyethylene Terephthalate Production 61 FR 48208(F) 9/12/96

Polymerized Vinylidene Chloride Production *

Polymethyl Methacrylate Resins Production*

Polystyrene Production 61 FR 48208(F) 9/12/96

Polysulfide Rubber Production 61 FR 46906(F) 9/5/96

Polyvinyl Acetate Emulsions Production *

Polyvinyl Alcohol Production *

Polyvinyl Butyral Production *

Polyvinyl Chloride and Copolymers Production 65 FR 76958(P) 12/8/00

Reinforced Plastic Composites Production 66 FR 40324(P) 8/2/01

Styrene-Acrylonitrile Production 61 FR 48208(F) 9/12/96

Styrene-Butadiene Rubber and Latex Production 61 FR 46906(F) 9/5/96

Production of Inorganic Chemicals

Ammonium Sulfate Production–Caprolactam By-Product Plants *

Carbon Black Production 65 FR 76408(P) 12/6/00

Chlorine Production *

Cyanide Chemicals Manufacturing 65 FR 76408(P) 12/6/00

Fumed Silica Production 64 FR 63025(N) 11/18/99

Hydrochloric Acid Production *

Hydrogen Fluoride Production 64 FR 34853(F) 6/30/99

Phosphate Fertilizers Production 64 FR 31358(F) 6/10/99

Phosphoric Acid Manufacturing 64 FR 31358(F) 6/10/99

Production of Organic Chemicals

Ethylene Processes 65 FR 76408(P) 12/6/00


Quaternary Ammonium Compounds Production *

Synthetic Organic Chemical Manufacturing 59 FR 19402(F) 4/22/94

Miscellaneous Processes

Benzyltrimethylammonium Chloride Production *

Carbonyl Sulfide Production *

Chelating Agents Production *

Chlorinated Paraffins Production *

Chromic Acid Anodizing 60 FR 04948(F) 1/25/95

Combustion Sources at Kraft, Soda, and Sulfite Pulp and Paper Mills 66 FR 3180(F) 1/12/01

Commercial Dry Cleaning (Perchloroethylene)–Transfer Machines 58 FR 49354(F) 9/22/93

Commercial Sterilization Facilities 59 FR 62585(F) 12/6/94

Decorative Chromium Electroplating 60 FR 04948(F) 1/25/95

Ethylidene Norbornene Production *

Explosives Production *

Flexible Polyurethane Foam Fabrication Operations 66 FR 41718(P) 8/8/01

Halogenated Solvent Cleaners 59 FR 61801(F) 12/2/94

Hard Chromium Electroplating 60 FR 04948(F) 1/25/95

Hydrazine Production *

Industrial Cleaning (Perchloroethylene)–Dry-to-Dry machines 58 FR 49354(F) 9/22/93

Industrial Dry Cleaning (Perchloroethylene)–Transfer Machines 58 FR 49354(F) 9/22/93

Industrial Process Cooling Towers 59 FR 46339(F) 9/8/94

Leather Finishing Operations 67 FR 9155(F) 2/27/02

Miscellaneous Viscose Processes 65 FR 52166(F) 8/28/00

OBPA/1,3-Diisocyanate Production *

Paint Stripping Operations *

Photographic Chemicals Production *

Phthalate Plasticizers Production *

Plywood and Composite Wood Products *

Pulp and Paper Production 65 FR 80755(F) 12/22/00

Rubber Chemicals Manufacturing *

Rubber Tire Manufacturing 63 FR 62414(P) 10/18/00

Semiconductor Manufacturing *

Symmetrical Tetrachloropyridine Production *

Tetrahydrobenzaldehyde Manufacture 63 FR 26078(F) 5/21/98

Wet-Formed Fiberglass Mat Production 65 FR 34277(P) 5/26/00


D. Title V OperatingPermits

For many facilities, the new federal oper-ating permit program established under TitleV of the CAA will cover all sources of air-borne emissions.6 Generally, it requires a per-mit for any facility emitting or having thepotential to emit more than 100 tpy of anyair pollutants though lower thresholds applyin non-attainment areas.7 Permits are alsorequired for all sources subject to MACT orNSPS standards, the Title IV acid rain pro-gram, and new source review permits underParts C and D of Title V. All airborne emis-sion requirements that apply to an industrialfacility, including emission limitations, oper-ational requirements, monitoring require-ments, and reporting requirements, will beincorporated in its operating permit. A TitleV permit provides a vehicle for ensuring thatexisting air quality control requirements areappropriately applied to facility emissionunits.

Under the new program, operating permitsthat meet federal requirements will generallybe issued by state agencies. In developingindividual permits, states can determinewhether to explicitly apply emission limita-tions and controls to waste managementunits. See Section F of this chapter (ADecision Guide to Applicable CAARequirements), and consult with federal,state, and local air program staff to determineif your waste management unit is subject toairborne emission limits and controls underCAA regulations. Listings of EPA regional andstate air pollution control agencies can beobtained from the States and Territorial AirPollution Program Administrators (STAPPA)

& Association of Local Air Pollution ControlOfficials (ALAPCO). STAPPA/ALAPCO’s Website is <www.cleanairworld.org/scripts/us_temp.asp?id=307>.

E. Federal AirborneEmission Regulations forSolid WasteManagement Activities

While EPA has not established airborneemission regulations for industrial waste man-agement units under RCRA, standards devel-oped for hazardous waste management unitsand municipal solid waste landfills (MSWLFs)can serve as a guide in evaluating the need forcontrols at specific units.

1. Hazardous WasteManagement Unit AirborneEmission Regulations

Under Section 3004(n) of RCRA, EPAestablished standards for the monitoring andcontrol of airborne emissions from hazardouswaste treatment, storage, and disposal facili-ties. Subparts AA, BB, and CC of 40 CFR Part264 address VOC releases from process vents,equipment leaks, tanks, surface impound-ments, and containers. Summaries ofSubparts AA, BB, and CC are provided in thetext box on the next page.

2. Municipal Solid Waste LandfillAirborne Emission Regulations

On March 12, 1996, EPA promulgated air-borne emission regulations for large new andexisting MSWLFs.8 These regulations apply toall new MSWLFs constructed or modified on

6 Federal Operating Permit Regulations were promulgated as 40 CFR Part 71 on July 1, 1996 andamended on February 19, 1999 to cover permits in Indian Country and states without fully approvedTitle V programs.

7 Under CAA Section 302(g), “air pollutant” is defined as any pollutant agent or combination of agents,including any physical, chemical, biological, or radioactive substance or matter which is emitted intoor otherwise enters the ambient air.

8 61 FR 9905; March 12, 1996, codified at 40 CFR Subpart WWW and CC (amended 63 FR 32750,June 16, 1998).5-10


5-11

or after May 30, 1991, and toexisting landfills that haveaccepted waste on or afterNovember 8, 1987. In additionto methane, MSWLFs potentiallyemit non-methane organic com-pounds (NMOCs) in the gasesgenerated during waste decom-position, as well as in combus-tion of the gases in controldevices, and from other sources,such as dust from vehicle trafficand emissions from leachatetreatment facilities or mainte-nance shops. Under the regula-tions, any affected MSWLF thatemits more than 50 Mg/yr (55tpy) of NMOCs is required toinstall controls.

Best demonstrated technologyrequirements for both new andexisting municipal landfills pre-scribe installation of a well-designed and well-operated gascollection system and a controldevice. The collection systemshould be designed to allowexpansion for new cells thatrequire controls. The controldevice (presumed to be a com-bustor) must demonstrate eitheran NMOC reduction of 98 per-cent by weight in the collectedgas or an outlet NMOC concen-tration of no more than 20 partsper million by volume (ppmv).

3. Offsite Waste andRecoveryOperations NESHAP

On July 1, 1996, EPA estab-lished standards for offsite wasteand recovery operations

Summary of Airborne EmissionRegulations for Hazardous WasteManagement Units

Subpart AA regulates organic emissions fromprocess vents associated with distillation, fractionation,thin film evaporation, solvent extraction, and air orstream stripping operations (40 CFR §§264.1030-1036). Subpart AA only applies to these types of unitsmanaging hazardous waste streams with organic con-centration levels of at least 10 parts per million byweight (ppmw). Subpart AA regulations require facili-ties with covered process vents to either reduce totalorganic emissions from all affected process vents at thefacility to below 3 lb/h and 3.1 tons/yr, or reduce emis-sions from all process vents by 95 percent through theuse of a control device, such as a closed-vent system,vapor recovery unit, flare, or other combustion unit.

Subpart BB sets inspection and maintenancerequirements for equipment, such as valves, pumps,compressors, pressure relief devices, sampling connec-tion systems, open-ended valves or lines, flanges, orcontrol devices that contain or contact hazardouswastes with organic concentrations of at least 10 per-cent by weight (40 CFR §§264.1050-1065). SubpartBB does not establish numeric criteria for reducingemissions, it simply establishes monitoring, leak detec-tion, and repair requirements.

Subpart CC establishes controls on tanks, surfaceimpoundments, and containers in which hazardouswaste has been placed ( 40 CFR §§264.1080-1091). Itapplies only to units containing hazardous waste withan average organic concentration greater than 500ppmw. Units managing hazardous waste that has beentreated to reduce the concentrations of organics by 95percent are exempt. Non-exempt surface impound-ments must have either a rigid cover or, if wastes arenot agitated or heated, a floating membrane cover.Closed vent systems are required to control the emis-sions from covered surface impoundments. These con-trol systems must achieve the same 95 percent emissionreductions described above under Subpart AA.

(OSWRO) that emit HAPs.9 To be covered byOSWRO, a facility must emit or have thepotential to emit at least 10 tpy of any singleHAP or at least 25 tpy of any combination ofHAPs. It must receive waste, used oil, or usedsolvents from off site that contain one ormore HAPs.10 In addition, the facility mustoperate one of the following: a hazardouswaste treatment, storage, or disposal facility;RCRA-exempt hazardous wastewater treat-ment operation; nonhazardous wastewatertreatment facility other than a publicly ownedtreatment facility; or a RCRA-exempt haz-ardous waste recycling or reprocessing opera-tion, used solvent recovery operation, or usedoil recovery operation.

OSWRO contains MACT standards toreduce HAP emissions from tanks, surfaceimpoundments, containers, oil-water separa-tors, individual drain systems, other materialconveyance systems, process vents, andequipment leaks. For example, OSWROestablishes two levels of air emission controlsfor tanks depending on tank design capacityand the maximum organic HAP vapor pres-sure of the offsite material in the tank. Forprocess vents, control devices must achieve aminimum of 95 percent organic HAP emis-sion control. To control HAP emissions fromequipment leaks, the facility must implementleak detection and repair work practices andequipment modifications for those equipmentcomponents containing or contacting offsitewaste having a total organic HAP concentra-tion greater than 10 percent by weight (see40 CFR 63.683(d) cross ref. to 40 CFR63.680 (c) (3)).

F. A Decision Guide toApplicable CAARequirements

The following series of questions, summa-rized in Figure 1, is designed to help you iden-tify CAA requirements that might apply to afacility. This will not give you definitiveanswers, but can provide a useful starting pointfor consultation with federal, state, or local per-mitting authorities to determine which require-ments apply to a specific facility and whethersuch requirements address waste managementunits at the facility. If a facility is clearly notsubject to CAA requirements, assessing poten-tial risks from VOC emissions at a waste man-agement unit using the IWAIR or a site-specificrisk assessment is recommended.

The following steps provide a walkthrough of this evaluation process:

1. Determining Emissions Fromthe Unit

a) Determining VOC’s present in thewaste (waste characterization). Thenassume all the VOC’s are emittedfrom the unit, or

b) Estimating emissions using an emis-sions model. This also requires wastecharacterization. The CHEMDAT8model is a logical model for thesetypes of waste units. You can use theEPA version on the Internet or theone contained in the IWAIR model-ing tool for the Guide, or

c) Measuring emissions from the unit.While this is the most resource inten-sive alternative, measured data willprovide the most accurate information.

9 61 FR 34139; July 1, 1996, as amended, 64 FR 38970 (July 20, 1999) and 66 FR 1266 (January 8,2001).

10 OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAASection 112 list.


5-12


5-13

Characterize waste for potential air emissions

Conduct a risk evaluation using either:

a. Industrial Waste AirModel (IWAIR)

b. Site-specific riskassessment

You should conduct a more site-specific risk assessment

You should operate the unit in accordance with the recommendations of this guidance.

You should reduce risk to accept-able levels using treatment, con-

trols, or waste minimization

Does the waste

contain any of the 95 listed contaminants

in IWAIR?

Is the total

risk for the unitacceptable?

No further evaluation is

indicated

Facility is subjectto an air permit.

Consult withstate/local permitting authority

Is the unit part of an industrial facility

which is subject to a CAA Title V operating permit by virtue of being:

a. considered a major source; or

b. subject to NSPSs; or

c. considered a major source of HAPs and subject toNESHAP or MACT standards; or

d. subject to the acid rain program; or e. a unit subject to the

OSWRO NESHAP?

NO

NO

NO

YES

YES

OR

YES

Figure 1. Evaluating VOC Emission Risk

11 EPA can designate additional source categories subject to Title V operating permit requirements.

12 Implementation of air emission controls can generate new residual waste. Ensure that these wastes aremanaged appropriately, in compliance with state requirements and consistent with the Guide.

2. Is the Waste ManagementUnit Part of an IndustrialFacility That Is Subject to aCAA Title V OperatingPermit?

A facility is subject to a Title V operatingpermit if it is considered a major source of airpollutants, or is subject to a NSPS, NESHAP,or Title IV acid rain provision.11 As part of thepermitting process, the facility should developan emissions inventory. Some states haveadditional permitting requirements. If a facili-ty is subject to a Title V operating permit, allairborne emission requirements that apply toan industrial facility, including emission limi-tations as well as operational, monitoring, andreporting requirements, will be incorporatedin its operating permit. You should consultwith appropriate federal, state, and local airprogram staff to determine whether yourwaste management unit is subject to air emis-sion limits and controls.12

If you answer yes to any of the questionsin items a. through e. below, the facility issubject to a Title V operating permit. Consultwith the appropriate federal, state, and/orlocal permitting authority.

Whether or not emissions from wastemanagement unit(s) will be specificallyaddressed through the permit processdepends on a number of factors, includingthe type of facility and CAA requirementsand state permitting resources and priorities.It is prudent, when there are no applicableair permit requirements, to assess whetherthere might be risks associated with wastemanagement units and to address thesepotential risks.

If you answer no to all the questionsbelow, continue to Step 3.

a. Is the facility considered a majorsource?

If the facility meets any of the followingthree definitions, it is considered a majorsource (under 40 CFR § 70.2) and subject toTitle V operating permit requirements.

i. Any stationary source or group ofstationary sources that emits or hasthe potential to emit at least 100 tpyof any air pollutant.

ii. Any stationary source or group ofstationary sources that emits or hasthe potential to emit at least 10 tpyof any single HAP or at least 25 tpyof any combination of HAPs.

iii. A stationary source or group of sta-tionary sources subject to the nonat-tainment area provisions of CAA TitleI that emits, or has the potential toemit, above the threshold values forits nonattainment area category. Thenonattainment area category and thesource’s emission levels for VOCs andNOx, particulate matter (PM-10), andcarbon monoxide (CO) determinewhether the stationary source meetsthe definition of a “major source.”For nonattainment areas, stationarysources are considered “major

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Stationary source is defined as anybuilding, structure, facility, or installationthat emits or may emit any regulated airpollutant or any hazardous air pollutantlisted under Section 112 (b) of the Act.

An air pollutant is defined as any air pol-lution agent or combination of agents,including a physical, chemical, biological,radioactive substance or matter which isemitted into or otherwise enters the ambi-ent air.

sources” if they emit or have thepotential to emit at least the levelsfound in Table 4 below.

If yes, the facility is subject to a Title Voperating permit. Consult with the appropri-ate federal, state, and/or local permittingauthority.

If no, continue to determine whether thefacility is subject to a Title V operating permit.

b. Is the facility subject to NSPSs?

Any stationary source subject to a standardof performance under 40 CFR Part 60 is sub-ject to NSPS. (A list of NSPSs can be found inTable 1 above.)

If yes, the facility is subject to a Title Voperating permit. Consult with the appropri-ate federal, state, and/or local permittingauthority.

If no, continue to determine if the facilityis subject to a Title V operating permit.

c. Is the facility a major source ofHAPs as defined by Section 112 ofCAA and subject to a NESHAP orMACT standard?

Under Title V of CAA, an operating permitis required for all facilities subject to a MACTstandard. NESHAPs or MACT standards arenational standards to reduce HAP emissions.Each MACT standard specifies particularoperations, processes, and/or wastes that arecovered. EPA has identified approximately170 source categories and subcategories thatare or will be subject to MACT standards.(Table 3 above lists the source categories forwhich EPA is required to promulgate MACTstandards.) MACT standards have been orwill be promulgated for all major source cate-gories of HAPs and for certain area sources.

If yes, the facility should be permittedunder CAA Title V. Consult with the appro-priate federal, state, and/or local permittingauthority.

If no, continue to determine if the facilitymust obtain a Title V operating permit.

d. Is the facility subject to the acid rainprogram under Title IV of CAA?

If a facility, such as afossil-fuel fired powerplant, is subject toemission reductionrequirements or limita-tions under the acidrain program, it mustobtain a Title V operat-ing permit (40 CFR §72.6). The acid rainprogram focuses on thereduction of annual sul-fur dioxide and nitro-gen oxides emissions.


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13 The nonattainment categories are based upon the severity of the area’s pollution problems. The four cate-gories for VOCs and NOx range from Moderate to Extreme. Moderate areas are the closest to meeting theattainment standard, and require the least amount of action. Nonattainment areas with more serious airquality problems must implement various control measures. The worse the air quality, the more controlsareas will have to implement. PM-10 and CO have only two categories, Moderate and Serious.

Nonattainment VOCs or NOx PM-10 COArea Category13

Marginal or 100 tpy 100 tpy 100 tpyModerate

Serious 50 tpy 70 tpy 50 tpy

Severe 25 tpy — —

Extreme 10 tpy — —

Table 4.

Major Source Determination in Nonattainment Areas

If yes, the facility must obtain a Title Vpermit. Consult with the appropriate federal,state, and/or local permitting authority.

When you consult with the appropriatepermitting authority, it is important to clarifywhether waste management units at the facil-ity are addressed by the requirements. Ifwaste management units will not beaddressed through the permit process, youshould evaluate VOC emission risks.

If no, continue to determine if the facilitymust obtain a Title V operating permit.

e. Is the waste management unitsubject to the OSWRO NESHAP?This is just an example of the typesof questions you will need toanswer to determine whether aNESHAP or MACT standard coversyour facility.

To be covered by the OSWRO standards,your facility must meet all these conditions:

i. Be identified as a major source ofHAP emissions.

ii. Receive waste, used oil, or used sol-vents (subject to certain exclusions,40 CFR 63.680 (b) (2)) from off sitethat contain one or more HAPs.14

iii. Operate one of the following sixtypes of waste management or recov-ery operations (see 40 CFR 63.680(a) (2)):

• Hazardous waste treatment, storage,or disposal facility.

• RCRA-exempt hazardous wastewatertreatment operation.

• Nonhazardous wastewater treatmentfacility other than a publicly ownedtreatment facility.

• RCRA-exempt hazardous waste recy-cling or reprocessing operation.

• Used solvent recovery operations.

• Used oil recovery operations.

If yes, the unit should be covered by theOSWRO standards and Title V permitting.Consult with the appropriate federal, state,and/or local permitting authority.

If no, it is highly recommended that youconduct an air risk evaluation as set out instep 3.

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A major source under Title III isdefined as any stationary source orgroup of stationary sources that emits orhas the potential to emit at least 10 tpyof any single hazardous air pollutant(HAP) or at least 25 tpy of any combina-tion of HAPs.

An area source is any stationarysource which is not a major source butwhich might be subject to controls. Areasources represent a collection of facilitiesand emission points for a specific geo-graphic area. Most area sources aresmall, but the collective volume of largenumbers of facilities can be a concern indensely developed areas, such as urbanneighborhoods and industrial areas.Examples of areas sources subject toMACT standards include chromic acidanodizing, commercial sterilization facil-ities, decorative chromium electroplat-ing, hard chromium electroplating,secondary lead smelting, and halogenat-ed solvent cleaners.

HAPs are any of the 188 pollutantslisted in Section 112(b) of CAA. (Table 2above identifies the 188 HAPs.)

14 OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAASection 112 list.

3. Conducting a Risk EvaluationUsing One of the FollowingOptions:

a. Using IWAIR included with theGuide if your unit contains any of the95 contaminants that are covered inthe model.

b. Initiating a site-specific risk assess-ment for individual units. Total alltarget constituents from all applicableunits and consider emissions fromother sources at the facility as well.

II. Assessing RiskAir acts as a medium for the transport of

airborne contamination and, therefore, con-stitutes an exposure pathway of potentialconcern. Models that can predict the fate andtransport of chemical emissions in the atmos-phere can provide an important tool for eval-uating and protecting air quality. TheIndustrial Waste Air Model (IWAIR) includedin the Guide was developed to assist facilitymanagers, regulatory agency staff, and thepublic in evaluating inhalation risks fromwaste management unit emissions. AlthoughIWAIR is simple to use, it is still essential tounderstand the basic concepts of atmosphericmodeling to be able to interpret the resultsand understand the nature of any uncertain-ties. The purpose of this section is to providegeneral information on the atmosphere,chemical transport in the atmosphere, andthe risks associated with inhalation of chemi-cals so you can understand important factorsto consider when performing a risk assess-ment for the air pathway.

From a risk perspective, because humansare continuously exposed to air, the presenceof chemicals in air is important to consider inany type of assessment. If chemicals build upto high concentrations in a localized area,

human health can be compromised. The con-centration of chemicals in a localized area andthe resulting air pollution that can occur in theatmosphere is dependent upon the quantityand the rate of the emissions from a sourceand the ability of the atmosphere to dispersethe chemicals. Both meteorological and geo-graphic conditions in a local area will influ-ence the emission rate and subsequentdispersion of a chemical. For example, themeteorologic stability of the atmosphere, a fac-tor dependent on air temperature, influenceswhether the emission stream will rise and mixwith a larger volume of air (resulting in thedilution of pollutants) or if the emissionsstream will remain close to the ground. Figure2 is a conceptual diagram of a waste site illus-trating potential paths of human exposurethrough air.

A. Assessing Risks Associatedwith Inhalation ofAmbient Air

In any type of risk assessment, there arebasic steps that are necessary for gatheringand evaluating data. An overview of some ofthese steps is presented in this section toassist you in understanding conceptually theinformation discussed in the IWAIR section(Section B). The components of a risk assess-ment that are discussed in this section are:identification of chemicals of concern, sourcecharacterization, exposure assessment, andrisk characterization. Each of these steps isdescribed below as it applies specifically torisk resulting from the inhalation of organicchemicals emitted from waste managementunits to the ambient air.

Identification of Chemicals of Concern

A preliminary step in any risk assessmentis the identification of chemicals of concern.These are the chemicals present that areanticipated to have potential health effects as


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a result of their concentrations or toxicityfactors. An assessment is performed for agiven source, to evaluate chemical concentra-tions and toxicity of different chemicals.Based on these factors along with potentialmechanisms of transport and exposure path-ways, the decision is made to include orexclude chemicals in the risk assessment.

Source Characterization

In this step, the critical aspects of thesource (e.g., type of WMU, size, chemicalconcentrations, location) are necessary toobtain. When modeling an area source, suchas those included in the Guide, the amountof a given chemical that volatilizes and dis-perses from a source is critically dependenton the total surface area exposed. The sourcecharacterization should include informationon the surface area and elevation of the unit.The volatilization is also dependent on otherspecific attributes related to the waste man-agement practices. Waste management prac-tices of importance include applicationfrequency in land application units and thedegree of aeration that occurs in a surfaceimpoundment. Knowledge of the overall con-tent of the waste being deposited in the

WMU is also needed to estimate chemicalvolatilization. Depending on its chemicalcharacteristics, a chemical can bind with theother constituents in a waste, decreasing itsemissions to the ambient air. Source charac-terization involves defining each of these keyparameters for the WMU being modeled. Theaccuracy of projections concerning volatiliza-tion of chemicals from WMUs into ambientair is improved if more site-specific informa-tion is used in characterizing the source.

Exposure Assessment

The goal of an exposure assessment is toestimate the amount of a chemical that isavailable and is taken in by an individual,typically referred to as a receptor. An expo-sure assessment is performed in two steps: 1)the first step uses fate and transport model-ing to determine the chemical concentrationin air at a specified receptor location and, 2)the second step estimates the amount of thechemical the receptor will intake by identify-ing life-style activity patterns. The first step,the fate and transport modeling, uses a com-bination of an emission and dispersion modelto estimate the amount of chemical that indi-viduals residing or working within the vicini-

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Figure 2. Conceptual Site Diagram

ty of the source are exposed to throughinhalation of ambient air. When a chemicalvolatilizes from a WMU into the ambient air,it is subjected to a number of forces thatresult in its diffusion and transport away fromthe point of release.

In modeling the movement of the volatilechemical away from the WMU, it is oftenassumed that the chemical behaves as aplume (i.e., the chemical is continuouslyemitted into the environment) whose move-ment is modeled to produce estimated airconcentrations at points of interest. Thisprocess is illustrated in Figure 3.

The pattern of diffusion and movement ofchemicals that volatilize from WMUs dependson a number of interrelated factors. The ulti-mate concentration and fate of emissions tothe air are most significantly impacted bythree meteorologic conditions: atmosphericstability, wind speed, and wind direction.These meteorologic factors interact to deter-mine the ultimate concentration of a pollu-tant in a localized area.

• Atmospheric stability: The stabilityof the atmosphere is influenced bythe vertical temperature structure ofthe air above the emission source. Ina stable environment, there is little orno movement of air parcels, and,

consequently, little or no movementand mixing of contaminants. In sucha stable air environment, chemicalsbecome “trapped” and unable tomove. Conversely, in an unstableenvironment there is significant mix-ing and therefore greater dispersionand dilution of the plume.15

• Prevailing wind patterns and theirinteraction with land features: Thenature of the wind patterns immedi-ately surrounding the WMU can sig-nificantly impact the local airconcentrations of airborne chemicals.Prevailing wind patterns combinewith topographic features such ashills and buildings to affect themovement of the plume. Uponrelease, the initial direction that emis-sions will travel is the direction of thewind. The strength of the wind willdetermine how dilute the concentra-tion of the pollutant will be in thatdirection. For example, if a strongwind is present at the time the pollu-tants are released, it is likely the pol-lutants will rapidly leave the sourceand become dispersed quickly into alarge volume of air.


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15 An example of an unstable air environment is one in which the sun shining on the earth’s surface hasresulted in warmer air at the earth’s surface. This warmer air will tend to rise, displacing any cooler airthat is on top of it. As these air parcels essentially switch places, significant mixing occurs.

Figure 3. Emissions from a WMU

In addition to these factors affecting thediffusion and transport of a plume away fromits point of release, the concentration of spe-cific chemicals in a plume can also be affect-ed by depletion. As volatile chemicals aretransported away from the WMU, they canbe removed from the ambient air through anumber of depletion mechanisms includingwet deposition (the removal of chemicals dueto precipitation) and dry deposition (theremoval of chemicals due to the forces ofgravity and impacts of the plume on featuressuch as vegetation). Chemicals can also betransformed chemically as they come in con-tact with the sun’s rays (i.e., photochemicaldegradation). Figure 4 illustrates the forcesacting to transport and deplete the contami-nant plume.

Because the chemicals being considered inIWAIR are volatiles and semi-volatiles and the

distances of transport being considered arerelatively short, the removal mechanismsshown in the figure are likely to have a rela-tively minor effect on plume concentration(both wet and dry deposition have significant-ly greater effects on airborne particulates).

Once the constituent’s ambient outdoorconcentration is determined, the receptor’sextent of contact with the pollutant must becharacterized. This step involves determiningthe location and activity patterns relevant tothe receptor being considered. In IWAIR, thereceptors are defined as residents and work-ers located at fixed distances from the WMU,and the only route of exposure consideredfor these receptors is the inhalation ofvolatiles. Typical activity patterns and bodyphysiology of workers and residents are usedto determine the intake of the constituent.Intake estimates quantify the extent to which

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Figure 4. Forces That Affect Contaminant Plumes.

the individual is exposed to the contaminantand are a function of the breathing rate,exposure concentration, exposure duration,exposure frequency, exposure averaging time(for carcinogens), and body weight.Estimated exposures are presented in terms ofthe mass of the chemical per kilogram ofreceptor body weight per day.

Risk Characterization

The concentrations that an individual takesinto his or her body that were determined dur-ing the exposure assessment phase are com-bined with toxicity values to generate riskestimates. Toxicity values used in IWAIRinclude inhalation-specific cancer slope factors(CSFs) for carcinogenic effects and referenceconcentrations (RfCs) for noncancer effects.These are explained in the General RiskSection in Chapter 1—Understanding Riskand Building Partnerships. Using these toxicityvalues, risk estimates are generated for carcino-genic effects and noncancer effects. Risk esti-mates for carcinogens are summed by IWAIR.

B. IWAIR ModelIWAIR is an interactive computer program

with three main components: an emissionsmodel; a dispersion model to estimate fateand transport of constituents through theatmosphere and determine ambient air con-centrations at specified receptor locations;and a risk model to calculate either the riskto exposed individuals or the waste con-stituent concentrations that can be protective-ly managed in the unit. To operate, theprogram requires only a limited amount ofsite-specific information, including facilitylocation, WMU characteristics, waste charac-teristics, and receptor information. A briefdescription of each component follows. TheIWAIR Technical Background Document (U.S.EPA, 2002a)contains a more detailed explana-tion of each.

1. Emissions ModelThe emissions model uses waste character-

ization, WMU, and facility information toestimate emissions for 95 constituents thatare identified in Table 5. The emission modelselected for incorporation into IWAIR is EPA’sCHEMDAT8 model. The entire CHEMDAT8model is run as the emission component ofthe IWAIR model. CHEMDAT8 has under-gone extensive review by both EPA andindustry representatives and is publicly avail-able from EPA’s Web page, <www.epa.gov/ttnchie1/software/water/water8.html>.

To facilitate emission modeling withCHEMDAT8, IWAIR prompts the user to pro-vide the required waste- and unit-specificdata. Once these data are entered, the modelcalculates and displays chemical-specificemission rates. If users decide not to developor use the CHEMDAT8 rates, they can entertheir own site-specific emission rates (g/m2-s).

2. Dispersion ModelIWAIR’s second modeling component esti-

mates dispersion of volatilized contaminantsand determines air concentrations at specifiedreceptor locations, using default dispersionfactors developed with EPA’s IndustrialSource Complex, Short-Term Model, version3 (ISCST3). ISCST3 was run to calculate dis-persion for a standardized unit emission rate(1 µg/m2 - s) to obtain a unitized air concen-tration (UAC), also called a dispersion factor,which is measured in µ/m3 per µg/m2-s. Thetotal air concentration estimates are thendeveloped by multiplying the constituent-specific emission rates derived from CHEM-DAT8 (or from another source) with asite-specific dispersion factor. RunningISCST3 to develop a new dispersion factorfor each location/WMU is very time consum-ing and requires extensive meteorologicaldata and technical expertise. ThereforeIWAIR incorporates default dispersion factors


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5-22


75-07-0

67-64-1

75-05-8

107-02-8

79-06-1

79-10-7

107-13-1

107-05-1

62-53-3

71-43-2

92-87-5

50-32-8

75-27-4

106-99-0

75-15-0

56-23-5

108-90-7

124-48-1

67-66-3

95-57-8

126-99-8

1006-10-15

1319-77-3

98-82-8

108-93-0

96-12-8

75-71-8

107-06-2

75-35-4

78-87-5

57-97-6

95-65-8

121-14-2

123-91-1

122-66-7

106-89-8

106-88-7

11-11-59

110-80-5

100-41-4

106-93-4

107-21-1

75-21-8

50-00-0

98-01-1

87-68-3

118-74-1

Table 5. Constituents Included in IWAIR

Chemical Compound Name Chemical Compound NameAbstracts Abstracts(CAS) (CAS)Number Number

Acetaldehyde

Acetone

Acetonitrile

Acrolein

Acrylamide

Acrylic acid

Acrylonitrile

Allyl chloide

Aniline

Benzene

Benzidine

Benzo(a)pyrene

Bromodichloromethane

Butadine, 1,3-

Carbon disulfide

Carbon tetrachloride

Chlorobenzene

Chlorodibromomethane

Chloroform

Chloropphenol, 2-

Chloroprene

cis-1,3-Dichloropropylene

Cresols (total)

Cumene

Cyclohexanol

Dibromo-3-chloropropane, 1,2-

Dichlorodifluoromethane

Dichloroethane, 1,2-

Dichloroethylene, 1,1-

Dichloropropane, 1,2-

Dimethylbenz[a]anthracene , 7,12-

Dimethylphenol, 3,4-

Dinitrotoluene, 2,4-

Dioxane, 1,4-

Diphenylhydrazine, 1,2-

Epichlorohydrin

Epoxybutane, 1,2-

Ethoxyethanol acetate, 2-

Ethoxyethanol, 2-

Ethylbenzene

Ethylene dibromide

Ethylene glycol

Ethylene oxide

Formaldehyde

Furfural

Hexachloro-1,3-butadiene

Hexchlorobenzene

77-47-4

67-72-1

78-59-1

7439-97-6

67-56-1

110-49-6

109-86-4

74-83-9

74-87-3

78-93-3

108-10-1

80-62-6

1634-04-4

56-49-5

75-09-2

68-12-2

91-20-3

110-54-3

98-95-3

79-46-9

55-18-5

924-16-3

930-55-2

95-50-1

95-53-4

106-46-7

108-95-2

85-44-9

75-56-9

110-86-1

100-42-5

1746-01-6

630-20-6

79-34-5

127-18-4

108-88-3

10061-02-6

75-25-2

76-13-1

120-82-1

71-55-6

79-00-5

79-01-6

75-69-4

121-44-8

108-05-4

75-01-4

1330-20-7

Hexachlorocyclopentadine

Hexachloroethane

Isophorone

Mercury

Methanol

Methoxyethanol acetate, 2-

Methoxyethanol, 2-

Methyl bromide

Methyl chloride

Methyl ethyl ketone

Methyl isobutyl ketone

Methyl methacrylate

Methyl tert-butyl ether

Methylcholanthrene, 3-

Methylene chloride

N-N-Dimethyl formamide

Naphthalene

n-Hexane

Nitrobenzene

Nitropropane, 2-

NiNitrosodiethylamine

N-Nitrosodi-n-butylamine

N-Nitrosoyrrolidine

o-Dichlorobenzene

o-Toluidine

p-Dichlorobenzene

Phenol

Phthalic anhydride

Propylene oxide

Pyridine

Stryene

TCDD-2,3,7,8-

Tetrachloroethane, 1,1,1,2-

Tetrachloroethane, 1,1,2,2-

Tetrachloroethylene

Toluene

trans-1,3-Dichloropropylene

Tribromomethane

Freon 113 (Trichloro-1,2,2- 1,1,2- trifluoroethane)

Trichlorobenzene, 1,2,4-

Trichloroethane, 1,1,1-

Trichloroethane, 1,1,2-

Trichloroethylene

Trichlorofluoromethane

Triethylamine

Vinyl acetate

Vinyl chloride

Xylenes

developed by ISCST3 for many separate sce-narios designed to cover a broad range ofunit characteristics, including:

• 60 meteorological stations, chosen torepresent the 9 general climateregions of the continental U.S.

• 4 unit types.

• 17 surface area sizes for landfills,land application units and surfaceimpoundments, and 11 surface areasizes and 7 heights for waste piles.

• 6 receptor distances from the unit(25, 50, 75, 150, 500, 1000 meters).

• 16 directions in relation to the edgeof the unit.

The default dispersion factors were derivedby modeling many scenarios with variouscombinations of parameters, then choosing asthe default the maximum dispersion factorfor each waste management unit/surfacearea/meteorological station/receptor distancecombination.

Based on the size and location of a unit, asspecified by a user, IWAIR selects an appro-priate dispersion factor from the default dis-persion factors in the model. If the userspecifies a unit surface area that falls betweentwo of the sizes already modeled, a linearinterpolation method will estimate dispersionin relation to the two closest unit sizes.

Alternatively, a user can enter a site-specif-ic dispersion factor developed by conductingindependent modeling with ISCST3 or with adifferent model and proceed to the next step,the risk calculation.

3. Risk ModelThe third component to the model com-

bines the constituent’s air concentration withreceptor exposure factors and toxicity bench-marks to calculate either the risk from con-

centrations managed in the unit or the wasteconcentration (Cw) in the unit that shouldnot be exceeded to protect human health. Incalculating either estimate, the model appliesdefault values for exposure factors, includinginhalation rate, body weight, exposure dura-tion, and exposure frequency. These defaultvalues are based on data presented in theExposure Factors Handbook (U.S. EPA, 1995a)and represent average exposure conditions.IWAIR maintains standard health benchmarks(CSFs for carcinogens and RfCs for noncar-cinogens) for 95 constituents. These healthbenchmarks are from the Integrated RiskInformation System (IRIS) and the HealthEffects Assessment Summary Tables (HEAST).IWAIR uses these data to perform either a for-ward calculation to obtain risk estimates or abackward calculation to obtain protectivewaste concentration estimates.

4. Estimation ProcessFigure 5 provides an overview of the step-

wise approach the user follows to calculaterisk or protective waste concentration esti-mates with IWAIR. The seven steps of theestimation process are shown down the rightside of the figure, and the user specifiedinputs are listed to the left of each step. Asthe user provides input data, the programproceeds to the next step. Each step of theestimation process is discussed below.

a. Select Calculation Method. The userselects one of two calculation meth-ods. Use the forward calculation toarrive at chemical-specific and cumu-lative risk estimates if the user knowsthe concentrations of constituents inthe waste. Use the backward calcula-tion method to estimate protectivewaste concentrations not to beexceeded in new units. The screenwhere this step is performed is shownin Figure 6.


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5-24


Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations:

This figure shows the steps in the tool to assist the user in developing risk or

protective waste concentration estimates.

User Specifies:Calculation option

User Specifies:WMU typeWMU information (e.g.,operating parameters)

User Specifies:Emission rate optionFacility location for meteorological input

User Specifies:Dispersion factor optionReceptor information (e.g., distance and type)

Risk calculationor

Allowable waste concentrationcalculation

Select Calculation Method

Identify WMU

Add/modify properties data, asdesired

Define the Waste Managed

Determine Emission Rates

Interpolated from ISCST3 defaultdispersion factors

orUser-specified dispersion factors

Determine Dispersion Factors

Calculates ambient air concentrations foreach receptor based on emission anddispersion data

Calculate Ambient Air Concentrations

Risk Calculation1. Chemical-specific carcinogenic risk2. Chemical-specific noncarcinogenic risk3. Total cancer risk

or

Allowable Waste Concentration (Cwaste) Calculation

Cwaste for wastewaters (mg/L)Cwaste for solid wastes (mg/kg)

Calculate Results

CHEMDAT8or

User-specified emission rates

User Specifies:Constituents (choose up to 6)Concentration for risk calculation

User Specifies:Risk level for allowable concentrationcalculation

Land application unitWaste pileSurface impoundment, aeratedand quiescentLandfill


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Figure 6. Screen 1, Method, Met Station, WMU.

A. Select calculation method

C. Select met station search option

Enter zip code and search for met station

Enter latitude and longitude and search for met station

D. View selected met station

B. Select WMU type

E. Select emission and dispersion option

Figure 7. Screen 2, Wastes Managed.

B. Select sorting option for identifying chemicals

C. Identify chemicals in waste

D. View selected chemicals

E. Enter waste concentrations

A. Add/ modify chemicals

b. Identify Waste Management Unit.Four WMU types can be modeled:surface impoundments (SIs), landapplication units (LAUs), active land-fills (LFs), and wastepiles (WPs). Foreach WMU, you will be asked tospecify some design and operatingparameters such as surface area,depth for surface impoundments andlandfills, height for wastepiles, andtilling depth for LAUs. The amountof unit specific data needed as inputwill vary depending on whether theuser elects to develop CHEMDAT8emission rates. IWAIR providesdefault values for several of the oper-ating parameters that the user canchoose, if appropriate.

c. Define Waste Managed. Specifyconstituents and concentrations inthe waste if you choose a forwardcalculation to arrive at chemical spe-cific risk estimates. If you choose abackward calculation to estimate pro-tective waste concentrations, thenspecify constituents of concern. Thescreen where this step is performedis shown in Figure 7.

d. Determine Emission Rates. You canelect to develop CHEMDAT8 emis-sion rates or provide your own site-specific emission rates for use incalculations. IWAIR will also ask forfacility location information to linkthe facility’s location to one of the 60IWAIR meteorological stations. Datafrom the meteorological stations pro-vide wind speed and temperatureinformation needed to develop emis-sion estimates. In some circum-stances the user might already haveemissions information from monitor-ing or a previous modeling exercise.As an alternative to using the CHEM-

DAT8 rates, a user can provide theirown site-specific emission ratesdeveloped with a different model orbased on emission measurements.

e. Determine Dispersion. The user canprovide site-specific unitized disper-sion factors (µg/m3 per µg/m2-s) orhave the model develop dispersionfactors based on user-specified WMUinformation and the IWAIR defaultdispersion data. Because a number ofassumptions were made in develop-ing the IWAIR default dispersiondata you can elect to provide site-specific dispersion factors which canbe developed by conducting inde-pendent modeling with ISCST3 orwith a different model. Whether youuse IWAIR or provide dispersion fac-tors from another source, specify dis-tance to the receptor from the edgeof the WMU and the receptor type(i.e., resident or worker). These dataare used to define points of exposure.

f. Calculate Ambient AirConcentration. For each receptor,the model combines emission ratesand dispersion data to estimate ambi-ent air concentrations for all wasteconstituents of concern.

g. Calculate Results. The model calcu-lates results by combining estimatedambient air concentrations at a speci-fied exposure point with receptorexposure factors and toxicity bench-marks. Presentation of resultsdepends on whether you chose a for-ward or backward calculation:

Forward calculation: Results are estimates ofcancer and non-cancer risks from inhalationexposure to volatilized constituents in thewaste. If risks are too high, options are: 1)implement unit controls to reduce volatile airemissions, 2) implement pollution preven-

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tion or treatment to reduce volatile organiccompound (VOC) concentrations before thewaste enters the unit, or 3) conduct a fullsite-specific risk assessment to more preciselycharacterize risks from the unit.

Backward calculation: Results are estimates ofconstituent concentrations in waste that can beprotectively managed in the unit so as not toexceed a defined risk level (e.g., 1 x 10-6 orhazard quotient of 1) for specified receptors. Atarget risk level for your site can be calculatedbased on a number of site-specific factorsincluding, proximity to potential receptors,waste characteristics, and waste managementpractices. This information should be used todetermine preferred characteristics for wastesentering the unit. There are several options if itappears that planned waste concentrationsmight be too high: 1) implement pollutionprevention or treatment to reduce VOC con-centrations in the waste, 2) modify waste man-agement practices to better control VOCs (forexample, use closed tanks rather than surfaceimpoundments), or 3) conduct a full site-spe-cific risk assessment to more precisely charac-terize risks from the unit.

5. Capabilities and Limitations ofthe Model

In many cases, IWAIR will provide a rea-sonable alternative to conducting a full-scalesite-specific risk analysis to determine if aWMU poses unacceptable risk to humanhealth. Because the model can accommodateonly a limited amount of site-specific infor-mation, however, it is important to under-stand its capabilities and recognize situationswhen it might not be appropriate to use.

Capabilities

• The model provides a reasonable rep-resentation of VOC inhalation risks

associated with waste managementunits.

• The model is easy-to-use andrequires a minimal amount of dataand expertise.

• The model is flexible and providesfeatures to meet a variety of userneeds.

• A user can enter emission and/or dis-persion factors derived from anothermodel (perhaps to avoid some of thelimitations below) and still useIWAIR to conduct a risk evaluation.

• The model can run a forward calcula-tion from the unit or a backward cal-culation from the receptor point.

• A user can modify health bench-marks (HBNs) and target risk level,when appropriate and in consultationwith other stakeholders.

Limitations

• Release Mechanisms and ExposureRoutes. The model considers expo-sures from breathing ambient air. Itdoes not address potential risksattributable to particulate releases nordoes it address risks associated withindirect routes of exposure (i.e, non-inhalation routes of exposure).Additionally, in the absence of user-specified emission rates, volatileemission estimates are developedwith CHEMDAT8 based on unit- andwaste-specific data. The CHEMDAT8model was developed to address onlyvolatile emissions from waste man-agement units. Competing mecha-nisms that can generate additionalexposures to the constituents in thewaste such as runoff, erosion, and


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particulate emissions are notaccounted for in the model.

• Waste Management Practices. Theuser specifies a number of unit-spe-cific parameters that significantlyimpact the inhalation pathway (e.g.,size, type, and location of WMU,which is important in identifyingmeteorological conditions). However,the model cannot accommodateinformation concerning control tech-nologies such as covers that mightinfluence the degree of volatilization(e.g., whether a wastepile is coveredimmediately after application of newwaste). In this case, it might be advis-able to generate site-specific emissionrates and enter those into IWAIR.

• Terrain and MeteorologicalConditions. If a facility is located inan area of intermediate or complexterrain or with unusual meteorologi-cal conditions, it might be advisableto either 1) generate site-specific airdispersion modeling results for thesite and enter those results into theprogram, or 2) use a site-specific riskmodeling approach different fromIWAIR. The model will inform theuser which of the 60 meteorologicalstations is used for a facility. If thelocal meteorological conditions arevery different from the site chosen bythe model, it would be more accurateto choose a different model.

The terrain type surrounding a facili-ty can impact air dispersion model-ing results and ultimately riskestimates. In performing air disper-sion modeling to develop the IWAIRdefault dispersion factors, the modelISCST3 assumes the area around theWMU is of simple or flat terrain. TheGuideline on Air Quality Models (U.S.

EPA, 1993) can assist users in deter-mining whether a facility is in anarea of simple, intermediate, or com-plex terrain.

• Receptor Type and Location.IWAIR has predetermined adultworker and resident receptors, sixreceptor locations, and predeter-mined exposure factors. The programcannot be used to characterize riskfor other possible exposure scenarios.For example, the model can not eval-uate receptors that are closer to theunit than 25 meters or those that arefurther from the unit than 1,000meters. If the population of concernfor your facility is located beyond thelimits used in IWAIR, consider usinga model that is more appropriate forthe risks posed from your facility.

C. Site-specific RiskAnalysis

IWAIR is not the only model that can beapplicable to a site. In some cases, a site-spe-cific risk assessment might be more advanta-geous. A site-specific approach can betailored to accommodate the individual needsof a particular WMU. Such an approachwould rely on site-specific data and on theapplication of existing fate and transportmodels. Table 6 summarizes available emis-sions and/or dispersion models that can beapplied in a site-specific analysis. Practicalconsiderations include the source of themodel(s), the ease in obtaining the model(s),and the nature of the model(s) (i.e., is it pro-prietary), and the availability of site-specificdata required for use of the model. Finally,the model selection process should determinewhether or not the model has been verifiedagainst analytical solutions, other models,and/or field data. Proper models can beselected based on the physical and chemical

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Model Name Summary

Table 6

Source Characterization Models

AP-42 The EPA’s Compilation of Air Pollutant Emission Factors, Volume I: StationaryPoint and Area Sources (AP-42), is a compilation of emission factors for a widevariety of air emission sources, including fugitive dust sources (Section 13.2).Emission factors are included for paved roads, unpaved roads, heavy construc-tion operations, aggregate handling and storage piles, industrial wind erosion(this is the 1988 Cowherd model), and abrasive blasting. These are simple emis-sion factors or equations that relate emissions to inputs (e.g., silt loading or con-tent, moisture content, mean vehicle weight, area, activity level, and windspeed). Guidance is provided for most inputs, but the more site-specific theinput data used, the more accurate the results.

The entire AP-42 documentation is available at <www.epa.gov/ttn/chief/efinformation.html>.

CHEMDAT8 The CHEMDAT8 model allows the user to conduct source and chemical specificemissions modeling. CHEMDAT8 is a Lotus 1-2-3 spreadsheet that includes ana-lytical models to estimate volatile organic compound emissions from treatment,storage, and disposal facility processes under user-specified input parameters.CHEMDAT8 calculates the fractions of waste constituents of interest that are dis-tributed among pathways (partition fractions) applicable to the facility underanalysis.

Emissions modeling using CHEMDAT8 is conducted using data entered by theuser for unit-specific parameters. The user can choose to override the defaultdata and enter their estimates for these unit-specific parameters. Thus, modelingemissions using CHEMDAT8 can be done with a limited amount of site-specificinformation.

Available at <www.epa.gov/ttnchie1/software/water/water8.html>, hotline at919 541-5610 for more information.

Cowherd The Cowherd model, Rapid Assessment of Exposure to Particulate Emissionsfrom Surface Contamination Sites, allows the user to calculate particulate emis-sion rates for wind erosion using data on wind speed and various parametersthat describe the surface being eroded. The latest (1988) version of this model isevent-based (i.e., erosion is modeled as occurring in response to specific eventsin which the wind speed exceeds levels needed to cause wind erosion). An older(1985) version of the model is not event-based (i.e., erosion is modeled as along-term average, without regard to specific wind speed patterns over time).The older version is less complicated and requires fewer inputs, but producesmore conservative results (i.e., higher emissions). The documentation on bothmodels provides guidance on developing all inputs. Both require data on windspeed (fastest mile for the 1988 version and annual average for the 1985 ver-sion), anemometer height, roughness height, and threshold friction velocity. The1985 version also requires input on vegetative cover. The 1988 version requiresdata on number of disturbances per year and, if the source is not a flat surface,pile shape and orientation to the fastest mile.

The 1985 version of the model is presented in Rapid Assessment of Exposures toParticulate Emissions from Surface Contamination Sites (U.S. EPA, 1985). Officeof Health and Environmental Assessment, Washington DC.

The 1988 version of the model is available as part of AP-42, Section 13.2.5 (seeabove).

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Model Name Summary

Table 6


ISCLT3 The Industrial Source Complex Model-Long Term, ISCLT3, is a steady stateGaussian plume dispersion model that can be used to model dispersion of con-tinuous emissions from point or area sources over transport distances of lessthan 50km. It can estimate air concentration for vapors and particles, and drydeposition rates for particles (but not vapors), and can produce these outputsaveraged over seasonal, annual, or longer time frames. ISCLT3 inputs includereadily available meteorological data known as STAR (STability ARray) sum-maries (these are joint frequency distributions of wind speed class by winddirection sector and stability class, and are available from the National ClimateData Center in Asheville, North Carolina), and information on source character-istics (such as height, area, emission rate), receptor locations, and a variety ofmodeling options (such as rural or urban). Limitations of ISCLT3 include inabili-ty to model wet deposition, deposition of vapors, complex terrain, or shorteraveraging times than seasonal, all of which can be modeled by ISCST3. In addi-tion, the area source algorithm used in ISCLT3 is less accurate than the one usedin ISCST3. The runtime for area sources, however, is significantly shorter forISCLT3 than for ISCST3.

ISCLT3 is available at <www.epa.gov/scram001/tt22.htm>.

ISCST3 A steady-state Gaussian plume dispersion model that can estimate concentration,dry deposition rates (particles only), and wet deposition rates. Is applicable forcontinuous emissions, industrial source complexes, rural or urban areas, simpleor complex terrain, transport distances of less than 50 km, and averaging timesfrom hourly to annual.

Available at <www.epa.gov/scram001/tt22.htm>.

Landfill Air Emissions Estimation Used to estimate emission rates for methane, carbon dioxide, nonmethane Model (LAEEM) volatile organic compounds, and other hazardous air pollutants from municipal

solid waste landfills. The mathematical model is based on a first order decayequation that can be run using site-specific data supplied by the user for theparameters needed to estimate emissions or, if data are not available, usingdefault value sets included in the model.

Developed by the Clean Air Technology Center (CATC). Can be used to estimateemission rates for methane, carbon dioxide, nonmethane organic compounds,and individual air pollutants from landfills. Can also be used by landfill ownersand operators to determine if a landfill is subject to the control requirements ofthe federal New Source Performance Standard (NSPS) for new municipal solidwaste (MSW) landfills (40 CFR 60 Subpart WWW) or the emission guidelinesfor existing MSW landfills (40 CFR 60 Subpart CC).

Developed for municipal solid waste landfills; might not be appropriate for allindustrial waste management units.

Available at <www.epa.gov/ttn/chief/software/index.html>.


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Model Name Summary

Table 6


Wastewater Treatment Compound WATER9 is a Windows based computer program and consists of analytical Property Processor and Air Emissions expressions for estimating air emissions of individual waste constituents in Estimator Program (WATER9) wastewater collection, storage, treatment, and disposal facilities; a database list-

ing many of the organic compounds; and procedures for obtaining reports ofconstituent fates, including air emissions and treatment effectiveness.

WATER9 is a significant upgrade of features previously obtained in the computerprograms WATER8, Chem9, and Chemdat8. WATER9 contains a set of modelunits that can be used together in a project to provide a model for an entire facil-ity. WATER9 is able to evaluate a full facility that contains multiple wastewaterinlet streams, multiple collection systems, and complex treatment configurations.It also provides separate emission estimates for each individual compound that isidentified as a constituent of the wastes.

WATER9 has the ability to use site-specific compound property information, andthe ability to estimate missing compound property values. Estimates of the total airemissions from the wastes are obtained by summing the estimates for the individ-ual compounds. The EPA document Air Emissions Models for Waste and Wastewater(U.S. EPA, 1994a) includes the equations used in the WATER9 model.

Available at <www.epa.gov/ttnchie1/software/water/water9/index.html>.Contact the Air Emissions Model Hotline at 919 541-5610 for support or moreinformation.

Toxic Modeling System Short Term An interactive PC-based system to analyze intermittent emissions from toxic (TOXST) sources. Estimates the dispersion of toxic air pollutants from point, area, and

volume sources at a complex industrial site. This system uses a Monte Carlo sim-ulation to allow the estimation of ambient concentration impacts for single andmultiple pollutants from continuous and intermittent sources. In addition, themodel estimates the average annual frequency with which user-specified concen-tration thresholds are expected to be exceeded at receptor sites around the mod-eled facility. TOXST requires the use of ISCT3 model input files for physicalsource parameters.

Available at <www.epa.gov/rgytgrnj/programs/artd/toxics/arpp/etools.htm>.

Toxic Screening Model (TSCREEN) TSCREEN, a Model for Screening Toxic Air Pollutant Concentrations, should beused in conjunction with the “Workbook of Screening Techniques for AssessingImpacts of Toxic Air Pollutants.” The air toxics dispersion screening modelsimbedded in TSCREEN that are used for the various scenarios are SCREEN2,RVD, PUFF, and the Britter-McQuaid model. Using TSCREEN, a particularrelease scenario is selected via input parameters, and TSCREEN model to simu-late that scenario. The model to be used and the worst case meteorological con-ditions are automatically selected based on criteria given in the workbook.TSCREEN has a front-end control program to the models that also provides, byuse of interactive menus and data entry screen, the same steps as the workbook.

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attributes of the site in question. As with allmodeling, however, you should consult withyour state prior to investing significantresources in a site-specific analysis. The statemight have preferred models or might be ableto help plan the analysis.

III. Emission ControlTechniques

A. Controlling ParticulateMatter

Particulate matter (PM) consists of air-borne solid and liquid particles. PM is easilyinhaled and can cause various health prob-lems. PM also impacts the environment bydecreasing visibility and harming plants aswell as transporting constituents off site.Constituents can sorb to particulate matterand, therefore, wind blown dust is a potentialpathway for constituents to leave the site. It isrecommended that facilities adopt controls toaddress emissions of airborne particulates.

Solid PM that becomes airborne directly orindirectly as a result of human activity, isreferred to as fugitive dust16 and it can begenerated from a number of different sources.The most common sources of fugitive dust atwaste management units include vehiculartraffic on unpaved roads and land-basedunits, wind erosion from land-based units,and waste handling procedures. Developing afugitive dust control plan is an efficient wayto tackle these problems. The plan shouldinclude a description of all operations con-ducted at the unit, a map, a list of all fugitivedust sources at the unit, and a description ofthe control measures that will be used tominimize fugitive dust emissions. OSHA hasestablished standards for occupational expo-sure to dust (see 29 CFR § 1910.1000). You

should check to see if your state also has reg-ulations or guidance concerning dust or fugi-tive emission control.

PM emissions at waste management unitsvary with the physical and chemical charac-teristics of waste streams; the volume of wastehandled; the size of the unit, its location, andassociated climate; and waste transportationand placement practices. The subsectionsbelow discuss the main PM-generating opera-tions and identify emission control tech-niques. The waste management units of mainconcern for PM emissions include landfills,waste piles, land application units, and closedsurface impoundments.

1. Vehicular Operations Waste and cover material are often trans-

ported to units using trucks. If the waste hasthe potential for PM to escape to the atmos-phere during transport, you should cover thewaste with tarps or place wastes in containerssuch as double bags or drums.17

A unit can also use vehicles to constructlifts in landfills, apply liquids to land applica-tion units, or dredge surface impoundments.Consider using “dedicated” equipment—vehi-cles that operate only within the unit and arenot routinely removed from the unit to per-form other activities. This practice reducesthe likelihood that equipment movement willspread contaminated PM outside the unit. Tocontrol PM emissions when equipment mustbe removed from the landfill unit, such as formaintenance, a wash station can remove anycontaminated material from the equipmentbefore it leaves the unit. You should ensurethat this is done in a curbed wash area wherewash water is captured and properly handled.

To minimize PM emissions from all vehi-cles, it is recommended that you constructtemporary roadways with gravel or other

16 Fugitive emissions are defined as emissions not caught by a capture system and therefore exclude PMemitted from exhaust stacks with control devices.

17 Containerizing wastes provides highly effective control of PM emissions, but, due to the large volume ofmany industrial waste streams, containerizing waste might not always be feasible.

coarse aggregate material to reduce silt con-tent and thus, dust generation. In addition,consider regularly cleaning paved roads andother travel surfaces of dust, mud, and conta-minated material.

In land application units, the entire appli-cation surface is often covered with a soil-waste mix. The most critical preventivecontrol measure, therefore, involves minimiz-ing contact between the application surfaceand waste delivery vehicles. If possible, allowonly dedicated application vehicles on thesurface, restricting delivery vehicles to a stag-ing or loading area where they deposit wasteinto application vehicles or holding tanks. Ifdelivery vehicles must enter the applicationarea, ensure that mud and waste are nottracked out and deposited on roadways,where they can dry and then be dispersed bywind or passing vehicles.

2. Waste Placement andHandling

PM emissions from waste placement andhandling activities are less likely if exposedmaterial has a high moisture content.Therefore, consider wetting the waste prior toloadout. Increasing the moisture content,however, might not be suitable for all wastestreams and can result in an unacceptableincrease in leachate production. To reducethe need for water or suppressants, cover orconfine freshly exposed material. In addition,consider increasing the moisture content ofthe cover material.

It can also be useful to apply water to unitsurfaces after waste placement. Water is gen-erally applied using a truck with a gravity orpressure feed. Watering might or might notbe advisable depending on application inten-sity and frequency, the potential for trackingof contaminated material off site, and climac-tic conditions. PM control efficiency generally

increases with application intensity and fre-quency but also depends on activity levels,climate, and initial surface conditions.Infrequent or low-intensity water applicationtypically will not provide effective control,while too frequent or high-intensity applica-tion can increase leachate volume, which canstrain leachate collection systems and threat-en ground water and surface water. Additionof excess water to bulk waste material or tounit surfaces also can reduce the structuralintegrity of the landfill lifts, increase trackingof contaminated mud off site, and increaseodor. These undesirable possibilities can havelong-term implications for the proper man-agement of a unit. Before instituting a water-ing program, therefore, ensure that additionof water does not produce undesirableimpacts on ground- and surface-water quality.You should consult with your state agencywith respect to these problems.

Chemical dust suppressants are an alterna-tive to water application. The suppressants aredetergent-like surfactants that increase thetotal number of droplets and allow particles tomore easily penetrate the droplets, increasingthe total surface area and contact potential.Adding a surfactant to a relatively small quan-tity of water and mixing vigorously producessmall-bubble, high-energy foam in the 100 to200 µm size range. The foam occupies verylittle liquid volume, and when applied to thesurface of the bulk material, wets the fines


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more effectively than water. When applied toa unit, suppressants cement loose materialinto a more impervious surface or form a sur-face which attracts and retains moisture.Examples of chemical dust suppressants areprovided in Table 7. The degree of controlachieved is a function of the applicationintensity and frequency and the dilution ratio.Chemical dust suppressants tend to requireless frequent application than water, reducingthe potential for leachate generation. Their

efficiency varies, depending on the same fac-tors as water application, as well as spraynozzle parameters, but generally fallsbetween 60 and 90 percent reduction in fugi-tive dust emissions. Suppressant costs, how-ever, can be high.

At land application units, if wastes containconsiderable moisture, PM can be suppressedthrough application of more waste ratherthan water or chemical suppressants. Thismethod, however, is only viable if it would

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* Mention of trade names or commercial products is not intended to constitute endorsement or recom-mendation for use.

Source: U.S. EPA, 1989.


Type Product Manufacturer

Bitumens AMS 2200, 2300® Arco Mine SciencesCoherex® Witco ChemicalDocal 1002® Douglas Oil CompanyPeneprime® Utah EmulsionsPetro Tac P® Syntech Products CorporationResinex® Neyra Industries, Inc.Retain® Dubois Chemical Company

Salts Calcium chloride Allied Chemical CorporationDowflake, Liquid Dow® Dow ChemicalDP-10® Wen-Don CorporationDust Ban 8806® Nalco Chemical CompanyDustgard® G.S.L. Minerals and Chemical CorporationSodium silicate The PQ Corporation

Adhesives Acrylic DLR-MS® Rohm and Haas CompanyBio Cat 300-1® Applied Natural Systems, Inc.CPB-12® Wen-Don CorporationCurasol AK® American Hoechst CorporationDCL-40A, 1801, 1803® Calgon CorporationDC-859, 875® Betz Laboratories, Inc.Dust Ban® Nalco Chemical CompanyFlambinder® Flambeau Paper CompanyLignosite® Georgia Pacific CorporationNorlig A, 12® Reed Lignin, Inc.Orzan Series® Crown Zellerbach CorporationSoil Gard® Walsh Chemical

Table 7. Example List of Chemical Suppressants*

not cause an exceedence of a design wasteapplication rate or exceed the capacity of soiland plants to assimilate waste.

At surface impoundments, the liquidnature of the waste means PM is not a majorconcern while the unit is operational. Inactiveor closed surface impoundments, however,can emit PM during scraping or bulldozingoperations to remove residual materials. Theuppermost layer of the low permeability soils,such as compacted clay, which can be used toline a surface impoundment, contains thehighest contaminant concentrations.Particulate emissions from this uppermostlayer, therefore, are the chief contributor tocontaminant emissions. When removingresiduals from active units, you should ensurethat equipment scrapes only the residuals,avoiding the liner below.

3. Wind ErosionWind erosion occurs when a dry surface is

exposed to the atmosphere. The effect is mostpronounced with bare surfaces of small parti-cles, such as silty soil; heavier or betteranchored material, such as stones or clumpsof vegetation, has limited erosion potentialand requires higher wind speeds before ero-sion can begin.

Compacted clay and in-situ soil liners tendto form crusts as their surfaces dry. Crustedsurfaces usually have little or no erosionpotential. Examine the crust thickness andstrength during site inspections. If the crustdoes not crumble easily the erosion potentialmight be minimal.

Wind fences or barriers are effective meansby which to control fugitive dust emissionsfrom open dust sources. The wind fence orbarrier reduces wind velocity and turbulencein an area whose length is many times theheight of the fence. This allows settling oflarge particles and reduces emissions from

the exposed surface. It can also shelter mate-rials handling operations to reduce entrain-ment during load-in and loadout. Windfences or barriers can be portable and eitherman-made structures or vegetative barriers,such as trees. A number of studies haveattempted to determine the effectiveness ofwind fences or barriers for the control ofwindblown dust under field conditions.Several of these studies have shown adecrease in wind velocity, however, thedegree of emissions reduction varies signifi-cantly from study to study depending on testconditions.

Other wind erosion control measuresinclude passive enclosures such as three-sided bunkers for the storage of bulk materi-als, storage silos for various types of aggregatematerial, and open-ended buildings. Suchenclosures are most easily used with small,temporary waste piles. At land applicationunits that use spray application, further winderosion control can be achieved simply bynot spraying waste on windy days.

Windblown PM emissions from a wastepile depend on how frequently the pile is dis-turbed, the moisture content of the waste, theproportion of aggregate fines, and the heightof the pile. When small-particle wastes areloaded onto a waste pile, the potential fordust emissions is at a maximum, as smallparticles are easily disaggregated and pickedup by wind. This tends to occur when mater-ial is either added to or removed from thepile or when the pile is otherwise reshaped.On the other hand, when the waste remainsundisturbed for long periods and is weath-ered, its potential for dust emissions can begreatly reduced. This occurs when moisturefrom precipitation and condensation causesaggregation and cementation of fine particlesto the surface of larger particles, and whenvegetation grows on the pile, shielding thesurface and strengthening it with roots.


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Finally, limiting the height of the pile canreduce PM emissions, as wind velocities gen-erally increase with distance from theground.

B. VOC Emission ControlTechniques

If air modeling indicates that VOC emis-sions are a concern, you should consider pol-lution prevention and treatment options toreduce risk. There are several control tech-niques you can use. Some are applied beforethe waste is placed in the unit, reducingemissions; others contain emissions thatoccur after waste placement; still othersprocess the captured emissions.

1. Choosing a Site to MinimizeAirborne Emission Problems

Careful site choice can reduce VOC emis-sions. Locations that are sheltered from windby trees or other natural features are prefer-able. Knowing the direction of prevailingwinds and determining whether the unitwould be upwind from existing and expectedfuture residences, businesses, or other popu-lation centers can result in better siting ofunits. After a unit is sited, observe winddirection during waste placement, and planor move work areas accordingly to reduceairborne emission impacts on neighbors.

2. Pretreatment of WastePretreating waste can remove organic com-

pounds and possibly eliminate the need forfurther air emission controls. Organicremoval or pretreatment is feasible for a vari-ety of wastes. These processes, which includesteam or air stripping, thin-film evaporation,solvent extraction, and distillation, can some-times remove essentially all of the highlyvolatile compounds from your waste.

Removal of the volatiles near the point ofgeneration can obviate the need for controlson your subsequent process units and canfacilitate recycling the recovered organicsback to the process.

The control efficiency of organic removaldepends on many factors, such as emissionsfrom the removal system, and the uncon-trolled emissions from management unitsbefore the removal device was installed.Generally, overall organic removal efficienciesof 98 to over 99 percent can be achieved.

3. Enclosure of UnitsYou might be able to control VOC emis-

sions from your landfill or waste pile byinstalling a flexible membrane cover, enclos-ing the unit in a rigid structure, or using anair-supported structure. Fans maintain posi-tive pressure to inflate an air-supported struc-ture. Some of the air-supported covers thathave been used consist of PVC-coated poly-ester with a polyvinyl fluoride film backing.The efficiency of air-supported structuresdepends primarily on how well the structureprevents leaks and how quickly any leaksthat do occur are detected. For effective con-trol, the air vented from the structure shouldbe sent to a control device, such as a carbonadsorber. Worker safety issues related toaccess to the interior of any flexible mem-brane cover or other pollutant concentrationsystem should also be considered.

Wind fences or barriers can also aid inreducing organic emissions by reducing airmixing on the leeward side of the screen. Inaddition, wind fences reduce soil moistureloss due to wind, which can in turn result indecreased VOC emissions.

Floating membrane covers provide controlon various types of surface impoundments,including water reservoirs in the westernUnited States. For successful control of

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organic compounds, the membrane mustprovide a seal at the edge of the impound-ment and rainwater must be removed. If gasis generated under the cover, vents and acontrol device might also be needed.Emission control depends primarily on thetype of membrane, its thickness, and thenature of the organic compounds in thewaste. Again, we recommend that you con-sult with your state or local air quality agencyto identify the most appropriate emissioncontrol for your impoundment.

4. Treatment of Captured VOCsIn some cases, waste will still emit some

VOCs despite waste reduction or pretreat-ment efforts. Enclosing the unit serves to pre-vent the immediate escape of these VOCs tothe atmosphere. To avoid eventually releasingVOCs through an enclosure’s ventilation sys-tem, a treatment system is necessary. Some ofthe better-known treatment methods are dis-cussed below; others also are be available.

a. Adsorption

Adsorption is the adherence of particles ofone substance, in this case VOCs, to the sur-face of another substance, in this case a filtra-tion or treatment matrix. The matrix can bereplaced or flushed when its surface becomessaturated with the collected VOCs.

Carbon Adsorption. In carbon adsorp-tion, organics are selectively collected on thesurface of a porous solid. Activated carbon isa common adsorbent because of its highinternal surface area: 1 gram of carbon canhave a surface area equal to that of a footballfield and can typically adsorb up to half itsweight in organics. For adsorption to beeffective, replace, regenerate, or recharge thecarbon when treatment efficiency begins todecline. In addition, any emissions from thedisposal or regeneration of the carbon should

be controlled. Control efficiencies of 97 to 99percent have been demonstrated for carbonadsorbers in many applications.

Biofiltration. While covering odorousmaterials with soil is a longstanding odorcontrol practice, the commercial use of biofil-tration is a relatively recent development.Biofilters reproduce and improve upon thesoil cover concept used in landfills. In abiofilter, gas emissions containing biodegrad-able VOCs pass through a bed packed withdamp, porous organic particles. The biologi-cally active filter bed then adsorbs the VOCs.Microorganisms attached to the wetted filtermaterial aerobically degrade the adsorbedchemical compounds. Biofiltration can be ahighly effective and low-cost alternative toother, more conventional, air pollution con-trol technologies such as thermal oxidation,catalytic incineration, condensation, carbonadsorption, and absorption. Successful com-mercial biofilter applications include treat-ment of gas emissions from compostingoperations, rendering plants, food and tobac-co processing, chemical manufacturing,foundries, and other industrial facilities.18

b. Condensation

Condensers work by cooling the ventedvapors to their dew point and removing theorganics as liquids. The efficiency of a con-denser is determined by the vapor phase con-centration of the specific organics and thecondenser temperature. Two common typesof condensers are contact condensers andsurface condensers.

c. Absorption

In absorption, the organics in the vent gasdissolve in a liquid. The contact between theabsorbing liquid and the vent gas is accom-plished in spray towers, scrubbers, or packedor plate columns. Some common solventsthat might be useful for volatile organics


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18 Mycock, J.C., J.D. McKenna, and L. Theodore. 1995. Handbook of Air Pollution Control Engineeringand Technology.

include water, mineral oils, or other non-volatile petroleum oils. Absorption efficien-cies of 60 to 96 percent have been reportedfor organics. The material removed from theabsorber can present a disposal or separationproblem. For example, organics must beremoved from the water or nonvolatile oilwithout losing them as emissions during thesolvent recovery or treatment process.

d. Vapor Combustion

Vapor combustion is another control tech-nique for vented vapors. The destruction oforganics can be accomplished in flares; ther-mal oxidizers, such as incinerators, boilers,or process heaters; and in catalytic oxidizers.Flares are an open combustion process inwhich oxygen is supplied by the air sur-rounding the flame. Flares are either operatedat ground level or elevated. Properly operatedflares can achieve destruction efficiencies ofat least 98 percent. Thermal vapor incinera-tors can also achieve destruction efficienciesof at least 98 percent with adequately hightemperature, good mixing, sufficient oxygen,and an adequate residence time. Catalytic

incinerators provide oxidation at tempera-tures lower than those required by thermalincinerators. Design considerations areimportant because the catalyst can beadversely affected by high temperatures, highconcentrations of organics, fouling from par-ticulate matter or polymers, and deactivationby halogens or certain metals.

5. Special Considerations forLand Application Units

Since spraying wastes increases contactbetween waste and air and promotes VOCemissions, if the waste contains volatileorganics you might want to choose anotherapplication method, such as subsurface injec-tion. During subsurface injection, waste issupplied to the injection unit directly from aremote holding tank and injected approxi-mately 6 inches into the soil; hence, thewaste is not exposed to the atmosphere. Inaddition, you should consider pretreating thewaste to remove the organics before placingit in the land application unit.

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We recommend that you consider the following issues when evaluating and controlling airemissions from industrial waste management units:

■■■■ Understand air pollution laws and regulations, and determine whether and how theyapply to a unit.

■■■■ Evaluate waste management units to identify possible sources of volatile organicemissions.

■■■■ Work with your state agency to evaluate and implement appropriate emission controltechniques, as necessary.

Protecting Air Activity List

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American Conference of Governmental Industrial Hygienists. 1997. Threshold Limit Values for ChemicalSubstances and Physical Agents and Biological Exposure Indices.

Christensen, T.H., R. Cossu, and R. Stegmann. 1995. Siting, Lining Drainage & Landfill Mechanics,Proceeding from Sardinia 95 Fifth International Landfill Symposium, Volume II.

Finn, L., and R. Spencer. 1987. Managing Biofilters for Consistent Odor and VOC Treatment. BioCycle.January.

Hazardous Waste Treatment, Storage and Disposal Facilities and Hazardous Waste Generators; Organic AirEmission Standards for Tanks, Surface Impoundments, and Containers; Final Rule. Federal Register. Volume59, Number 233, December 6, 1994. pp. 62896 - 62953.

Mycock, J.C., J.D. McKenna, and L. Theodore. 1995. Handbook of Air Pollution Control Engineering andTechnology.

National Ambient Air Quality Standards for Particulate Matter. Federal Register. Volume 62, Number 138, July18, 1997. pp. 38651 - 38701.

Orlemann, J.A., T.J. Kalman, J.A. Cummings, E.Y. Lin. 1983. Fugitive Dust Control Technology.

Robinson, W. 1986. The Solid Waste Handbook: A Practical Guide.

Texas Center for Policy Studies. 1995. Texas Environmental Almanac, Chapter 6, Air Quality. <www.tec.org>

U.S. EPA. 2002a. Industrial Waste Air Model Technical Background Document. EPA530-R-02-010.

U.S. EPA. 2002b. Industrial Waste Air Model (IWAIR) User’s Guide. EPA530-R-02-011.

U.S. EPA. 1998. Taking Toxics out of the Air: Progress in Setting “Maximum Achievable Control Technology”Standards Under the Clean Air Act. EPA451-K-98-001.

U.S. EPA. 1997a. Best Management Practices (BMPs) for Soil Treatment Technologies: Suggested OperationalGuidelines to Prevent Cross-Media Transfer of Contaminants During Clean-Up Activities. EPA530-R-97-007.

U.S. EPA. 1997b. Residual Risk Report to Congress. EPA453-R-97-001.

U.S. EPA. 1996. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. ThirdEdition.

Resources


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U.S. EPA. 1995a. Exposure Factors Handbook: Volumes 1-3. EPA600-P-95-002FA-C.

U.S. EPA. 1995b. Survey of Control Technologies for Low Concentration Organic Vapor Gas Streams.EPA456-R-95-003.

U.S. EPA. 1995c. User’s Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume I.EPA454-B-95-003a.

U.S. EPA. 1995d. User’s Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume II-Description of Model Algorithms. EPA454-B-95-003b.

U.S. EPA. 1994a. Air Emissions Models for Waste and Wastewater. EPA453-R-94-080A.

U.S. EPA. 1994b. Handbook: Control Techniques for Fugitive VOC Emissions from Chemical ProcessFacilities. EPA625-R-93-005.

U.S. EPA. 1994c. Toxic Modeling System Short-Term (TOXST) User’s Guide: Volume I. EPA454-R-94-058A.

U.S. EPA. 1993. Guideline on Air Quality Models. EPA450-2-78-027R-C

U.S. EPA. 1992a. Control of Air Emissions from Superfund Sites. EPA625-R-92-012.

U.S. EPA. 1992b. Protocol for Determining the Best Performing Model. EPA454-R-92-025.

U.S. EPA. 1992c. Seminar Publication: Organic Air Emissions from Waste Management Facilities. EPA625-R-92-003.

U.S. EPA. 1991. Control Technologies for Hazardous Air Pollutants. EPA625-6-91-014.

U.S. EPA. 1989. Hazardous Waste TSDF—Fugitive Particulate Matter Air Emissions Guidance Document.EPA450-3-89-019.

U.S. EPA. 1988. Compilation of Air Pollution Emission Factors. AP-42.

U.S. EPA. 1985. Rapid Assessment of Exposures to Particulate Emissions form Surface ContaminationSites.

Viessman, W., and M. Hammer. 1985. Water Supply and Pollution Control.

Resources (cont.)

Part IIIProtecting Surface Water

Chapter 6Protecting Surface Water

Contents

I. Determining the Quality and Health of Surface Waters ..........................................................................6 - 1

A. Water Quality Criteria............................................................................................................................6 - 2

B. Water Quality Standards ........................................................................................................................6 - 2

C. Total Maximum Daily Load (TMDL) Program........................................................................................6 - 3

II. Surface-Water Protection Programs Applicable to Waste Management Units ..........................................6 - 4

A. National Pollutant Discharge Elimination System (NPDES) Permit Program..........................................6 - 4

1. Storm-Water Discharges ....................................................................................................................6 - 5

2. Discharges to Surface Waters ............................................................................................................6 - 6

B. National Pretreatment Program..............................................................................................................6 - 6

1. Description of the National Pretreatment Program ............................................................................6 - 6

2. Treatment of Waste at POTW Plants..................................................................................................6 - 8

III. Understanding Fate and Transport of Pollutants ..................................................................................6 - 10

A. How Do Pollutants Move From Waste Management Units To Surface Water?......................................6 - 10

1. Overland Flow ................................................................................................................................6 - 10

2. Ground Water to Surface Water ......................................................................................................6 - 11

3. Air to Surface Water ........................................................................................................................6 - 11

B. What Happens When Pollutants Enter Surface Water? ........................................................................6 - 12

C. Pollutants Of Concern ........................................................................................................................6 - 13

IV. Protecting Surface Waters ....................................................................................................................6 - 13

A. Controls to Address Surface-Water Contamination from Overland Flow ............................................6 - 13

1. Baseline BMPs..................................................................................................................................6 - 18

2. Activity-Specific BMPs ....................................................................................................................6 - 18

3. Site-Specific BMPs ..........................................................................................................................6 - 19

B. Controls to Address Surface-water Contamination from Ground Water to Surface Water ....................6 - 29

C. Controls to Address Surface-water Contamination from Air to Surface Water......................................6 - 29

V. Methods of Calculating Run-on and Runoff Rates ................................................................................6 - 30

Protecting Surface Water Activity List..........................................................................................................6 - 33

Resources ....................................................................................................................................................6 - 34

Figures:

Figure 1. BMP Identification and Selection Flow Chart............................................................................6 - 17

Figure 2. Coverings..................................................................................................................................6 - 22

Figure 3. Silt Fence ..................................................................................................................................6 - 24

Contents (cont.)

Figure 4. Straw Bale ................................................................................................................................6 - 24

Figure 5. Storm Drain Inlet Protection ....................................................................................................6 - 25

Figure 6. Collection and Sedimentation Basin..........................................................................................6 - 26

Figure 7. Outlet Protection ......................................................................................................................6 - 27

Figure 8. Infiltration Trench ....................................................................................................................6 - 28

Figure 9. Typical Intensity-Duration-Frequency Curves ..........................................................................6 - 31

Tables:

Table 1. Biological and Chemical Processes Occurring in Surface Water Bodies ......................................6 - 14

Table 2. Priority Pollutants ......................................................................................................................6 - 15

Protecting Surface Water—Protecting Surface Water

6-1

Over 70 percent of the Earth’ssurface is water. Of all theEarth’s water, 97 percent isfound in the oceans and seas,while 3 percent is fresh water.

This fresh water is found in glaciers, lakes,ground water, wetlands, and rivers. Because

water is such a valuable commodity, the pro-tection of our surface waters should be every-one’s goal. Pollutants1 associated with wastemanagement units and storm-water dis-charges must be controlled.

This chapter summarizes how EPA andstates determine the quality of surface watersand subsequently describes the existing sur-face-water protection programs for ensuringthe health and integrity of waterbodies. Thefate and transport of pollutants in the surface-water environment is also discussed. Finally,various methods that are used to control pollu-tant discharges to surface waters are described.

I. Determining theQuality andHealth ofSurface Waters

The protection of aquatic resources is gov-erned by the Clean Water Act (CWA). Theobjective of the CWA is to “restore and main-tain the chemical, physical, and biological

1 To be consistent with the terminology used in the Clean Water Act, the term pollutant is used in thischapter in place of the term constituent. In this chapter, pollutant means an effluent or condition intro-duced to surface waters that results in degradation. Water pollutants include human and animal wastes,nutrients, soil and sediments, toxics, sewage, garbage, chemical wastes, and heat.

Protecting Surface Water


• Protect surface waters by limiting the discharge of pollutants into

the waters of the United States.

• Guard against inappropriate discharges of pollutants associated

with process wastewaters and storm water to ensure the safety of

the nation’s surface waters.

• Reduce storm-water discharges by complying with applicable regula-

tions, implementing available storm-water controls, and identifying

best management practices (BMPs) to control storm water.

This chapter will help you address thefollowing questions:

• What surface-water protection pro-grams are applicable to my wastemanagement unit?

• What are the objectives of run-on andrunoff control systems?

• What should be considered in design-ing surface-water protection systems?

• What BMPs should be implementedto protect surface waters from pollu-tants associated with waste manage-ment units?

• What are some of the engineering andphysical mechanisms available to con-trol storm water?

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integrity of the nation’s waters” (Section101(a)). Section 304(a) of the CWA authorizesEPA to publish recommended water qualitycriteria that provide guidance for states to usein adopting water quality standards underSection 303(c). Section 303 of the CWA alsoestablishes the Total Maximum Daily Load(TMDL) Program which requires EPA and thestates to identify waters not meeting waterquality standards and to establish TMDLs forthose waters.

A. Water Quality CriteriaUnder authority of Section 304 of the

CWA, EPA publishes water quality “criteria”that reflect available scientific information onthe maximum acceptable concentration levelsof specific chemicals in water that will protectaquatic life, human health, and drinkingwater. EPA has also established nutrient crite-ria (e.g., phosphorus and nitrogen) and bio-

logical criteria (i.e., biointegrity values). Thesecriteria are used by the states for developingenforceable water quality standards and iden-tifying problem areas.

Water quality criteria are developed fromtoxicity studies conducted on different organ-isms and from studies of the effects of toxiccompounds on humans. Federal water qualitycriteria specify the maximum exposure con-centrations that will provide protection ofaquatic life and human health. Generally,however, the water quality criteria describethe quality of water that will support a partic-ular use of the water body. For the protectionof aquatic life a two-value criterion has beenestablished to account for acute and chronictoxicity of pollutants. The human health crite-rion specifies the risk incurred with exposureto the toxic compounds at a specified concen-tration. The human health criterion is associ-ated with the increased risk of contracting adebilitating disease, such as cancer.

B. Water Quality StandardsWater quality standards are laws or regula-

tions that states (and authorized tribes) adoptto enhance and maintain the quality of waterand protect public health. States have the pri-mary responsibility for developing and imple-menting these standards. Water qualitystandards consist of three elements: 1) the“designated beneficial use” or “uses” of awaterbody or segment of a waterbody, 2) thewater quality “criteria” necessary to protectthe uses of that particular waterbody, and 3)an antidegradation policy. “Designated use” isa term that is specified in water quality stan-dards for a body of water or a segment of abody of water (e.g., a particular branch of ariver). Typical uses include public water sup-ply, propagation of fish and wildlife, andrecreational, agricultural, industrial, and navi-gational purposes. Each state develops its ownuse classification system based on the generic

What is water quality?Water quality reflects the composition ofwater as affected by natural causes andhuman activities, expressed in terms ofmeasurable quantities and related tointended water use. Water quality is deter-mined by comparing physical, chemical,biological, microbiological, and radiologi-cal quantities and parameters to a set ofstandards and criteria. Water quality isperceived differently by different people.For example, a public health official mightbe concerned with the bacterial and viralsafety of water used for drinking andbathing, while fishermen might be con-cerned that the quality of water be suffi-cient to provide the best habitat for fish.For each intended use and water qualitybenefit, different parameters can be usedto express water quality.


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uses cited in the CWA. The states may differ-entiate and subcategorize the types of usesthat are to be protected, such as cold-water orwarm-water fisheries, or specific species thatare to be protected (e.g., trout, salmon, bass).States may also designate special uses to pro-tect sensitive or valuable aquatic life or habi-tat. In addition, the water quality criteriaadopted into a state water quality standardmay or may not be the same number pub-lished by EPA under section 304. States havethe discretion to adjust the EPA’s criteria toreflect local environmental conditions andhuman exposure patterns.

The CWA requires that the states reviewtheir standards at least once every three yearsand submit the results to EPA for review. EPAis required to either approve or disapprovethe standards, depending on whether theymeet the requirements of the CWA. WhenEPA disapproves a standard, and the statedoes not revise the standard to meet EPA’sobjection, the CWA requires the Agency topropose substitute federal standards.

C. Total Maximum DailyLoad (TMDL) Program

Lasting solutions to water quality problemsand pollution control can be best achieved bylooking at the fate of all pollutants in a water-shed. The CWA requires EPA to administer

the total maximum daily load (TMDL) pro-gram, under which the states establish theallowable pollutant loadings for impairedwaterbodies (i.e., waterbodies not meetingstate water quality standards) based on their“waste assimilative capacity.” EPA mustapprove or disapprove TMDLs established bythe states. If EPA disapproves a state TMDL,EPA must establish a federal TMDL.

A TMDL is a calculation of the maximumamount of a pollutant that a waterbody canreceive and still meet water quality standards.The calculation must include a margin ofsafety to ensure that the waterbody can beused for the purposes the state has designat-ed. The calculation must also account for sea-sonal variation in water quality.

The quantity of pollutants that can be dis-charged into a surface-water body withoutuse impairment (also taking into account nat-ural inputs such as erosion) is known as the“assimilative capacity.” The assimilative capac-ity is the range of concentrations of a sub-stance or a mixture of substances that willnot impair attainment of water quality stan-dards. Typically, the assimilative capacity ofsurface-water bodies might be higher forbiodegradable organic matter, but it can bevery low for some toxic chemicals that accu-mulative in the tissues of aquatic organismsand become injurious to animals and peopleusing them as food.

U.S. EPA Selected Water Quality Criteria in Micrograms per Liter

Aquatic Life Human Health 10-6 RiskFreshwater Marine Water and Fish Fish Ingestion

Chemical Acute Chronic Acute Chronic Ingestion Only

Benzene 5300 — 5100 700 0.66 40

Cadmium — — 43 9.3 10 —

DDT 1.1 0.001 0.13 0.001 0.000024 0.000024

PCBs 2 0.014 10 0.03 0.000079 0.000079

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II. Surface-WaterProtectionProgramsApplicable toWasteManagementUnits

To ensure that a state’s water quality stan-dards and TMDLs are being met, discharges ofpollutants are regulated through the NationalPollutant Discharge Elimination System(NPDES) Permit Program and the NationalPretreatment Program. These permitting pro-grams are implemented and enforced at thestate or local level.

A. National PollutantDischarge EliminationSystem (NPDES) PermitProgram

The CWA requires most “point sources”(i.e., entities that discharge pollutants of anykind into waters of the United States) to havea permit establishing pollution limits, andspecifying monitoring and reporting require-ments. This permitting process is known asthe National Pollutant Discharge EliminationSystem (NPDES). Permits are issued for threetypes of wastes that are collected in sewersand treated at municipal wastewater treat-ment plants or that discharge directly intoreceiving waters: process wastewater, non-process wastewater, and storm water. Mostdischarges of municipal and industrial stormwater require NPDES permits, but someother storm water discharges do not requirepermits. To protect public health and aquaticlife and assure that every facility treats waste-water, NPDES permits include the followingterms and conditions.

• Site-specific effluent (or discharge)limitations.

• Standard and site-specific compliancemonitoring and reporting require-ments.

• Monitoring, reporting, and complianceschedules that must be met.

There are various methods used to monitorNPDES permit conditions. The permit willrequire the facility to sample its discharges andnotify EPA and the state regulatory agency ofthese results. In addition, the permit willrequire the facility to notify EPA and the stateregulatory agency when the facility determinesit is not in compliance with the requirementsof a permit. EPA and state regulatory agenciesalso send inspectors to facilities in order to

What is a watershed?Watersheds are areas of land that drain tosurface-waterbodies. A watershed general-ly includes lakes, rivers, estuaries, wet-lands, streams, and the surroundinglandscape. Ground-water recharge areasare also considered part of a watershed.Because watersheds are defined by natur-al hydrology, they represent the most log-ical basis for managing surface-waterresources. Managing the watershed as awhole allows state and local authorities togain a more complete understanding ofoverall conditions in an area and thecumulative stressors which affect the sur-face-water body. Information on EPA’sstrategy to protect and restore water qual-ity and aquatic ecosystems at the water-shed level can be found at <www.epa.gov/owow/watershed/index2.html>


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2 Initially, a group application option was available for facilities with similar activities to jointly submit asingle application for permit coverage. A multi-sector general permit was then issued based upon infor-mation provided in the group applications. The group application option was only used during the ini-tial stages of the program and is no longer available.

determine if they are in compliance with theconditions imposed under their permits.

NPDES permits typically establish specific“effluent limitations” relating to the type ofdischarge. For process wastewaters, the per-mit incorporates the more stringent of tech-nology-based limitations (either at 40 CFRParts 405 through 471 or developed on acase-by-case basis according to the permitwriter’s best professional judgement) or waterquality-based effluent limits (WQBELs).Some waste management units, such as sur-face impoundments, might have an NPDESpermit to discharge wastewaters directly tosurface waters. Other units might need anNPDES permit for storm-water discharges.

NPDES permits are issued by EPA or stateswith NPDES permitting authority. If you arelocated in a state with NPDES authority, youshould contact the state directly to determinethe requirements for your discharges. EPA’sOffice of Wastewater Management’s Web pagecontains a complete, updated list of the stateswith approved NPDES permit programs, aswell as a fact sheet and frequently askedquestions about the NPDES permit programat <cfpub.epa.gov/npdes>. If a state does nothave NPDES permitting authority, you shouldfollow any state requirements for dischargesand contact EPA to determine the applicablefederal requirements for discharges.

1. Storm-Water DischargesEPA has defined 11 categories of “storm-

water discharges associated with industrialactivity” that require a permit to discharge tonavigable waters (40 CFR Part 122.26 (b)(14)). These 11 categories are: 1) facilitiessubject to storm-water effluent limitationsguidelines, new source performance stan-dards (NSPS), or toxic pollutant effluent stan-dards under 40 CFR Part 129 (specifiesmanufacturers of 6 specific pesticides), 2)

“heavy” manufacturing facilities, 3) miningand oil and gas operations with “contaminat-ed” storm-water discharges, 4) hazardouswaste treatment, storage, or disposal facilities,5) landfills, land application sites, and opendumps, 6) recycling facilities, 7) steam elec-tric generating facilities, 8) transportationfacilities, 9) sewage treatment plants, 10)construction operations disturbing five ormore acres, and 11) other industrial facilitieswhere materials are exposed to storm water.Nonhazardous waste landfills, waste piles,and land application units are included incategory 5. Under a new Section 122.26(b)(15), storm water discharges from construc-tion operations disturbing between one andfive acres will be required to obtain a NPDESpermit effective in March 2003. There willbe, however, some waivers from permitrequirements available.

To provide flexibility for the regulatedcommunity in acquiring NPDES storm-waterdischarge permits, EPA has two NPDES per-mit application options: individual permitsand general permits.2 Applications for indi-

When is an NPDES permitneeded?To answer questions about whether ornot a facility needs to seek NPDES per-mit coverage, or to determine whether aparticular program is administered byEPA or a state agency, contact your stateor EPA regional storm-water office.Currently, 44 states and the U.S. VirginIslands have federally-approved stateNPDES permit programs. The following6 states do not have final EPA approval:Alaska, Arizona, Idaho, Massachusetts,New Hampshire, and New Mexico.

(As of March 2001)


vidual permits require the submission of asite drainage map, a narrative description ofthe site that identifies potential pollutantsources, and quantitative testing data for spe-cific parameters. General permits usuallyinvolve the submission of a Notice of Intent(NOI) that includes only general information,which is neither industry-specific or pollu-tant-specific and typically do not require thecollection of monitoring data. NPDES generalstorm-water permits typically require thedevelopment and implementation of storm-water pollution prevention plans and BMPsto limit pollutants in storm-water discharges.

The EPA has also issued the Multi-SectorGeneral Permit (60 FR 50803; September 29,1995) which covers 29 different industry sec-tors. The Agency reviewed, on a sector-by-

sector basis, information concerning industri-al activities, BMPs, materials stored outdoors,and end-of-pipe storm-water sampling data.Based on this review, EPA identified pollu-tants of concern in each industry sector, thesources of these pollutants, and the BMPsused to control them. The Multi-SectorGeneral Permit requires the submission of anNOI, as well as development and implemen-tation of a site-specific pollution preventionplan, as the basic storm-water control strategyfor each industry sector.

2. Discharges to Surface WatersMost surface impoundments that are

addressed by the Guide are part of a facility’swastewater treatment process that results inan NPDES-permitted discharge to surfacewaters. The NPDES permit only sets pollu-tion limits for the final discharge of treatedwastewater. Generally, the NPDES permitwould not establish any regulatory require-ments regarding the design or operation ofthe surface impoundments that are part ofthe treatment process except that, oncedesigned and constructed, a provisionrequires use of those treatment processesexcept in limited circumstances. Individualstate environmental agencies, under theirown statutory authorities, can imposerequirements on surface impoundmentdesign and operation.

B. National PretreatmentProgram

1. Description of the NationalPretreatment Program

For industrial facilities that dischargewastewaters to publicly owned treatmentworks (POTW) through domestic sewer lines,pretreatment of the wastewater may berequired (40 CFR Part 403). Under the

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What types of pollutantsare regulated by NPDES?

Conventional pollutants are containedin the sanitary wastes of households,businesses, and industries. These pollu-tants include human wastes, ground-upfood from sink disposals, and laundryand bath waters. Conventional pollutantsinclude fecal coliform, oil and grease,total suspended solids (TSS), biochemicaloxygen demand (BOD), and pH.

Toxic pollutants are particularly harm-ful to animal or plant life. They are pri-marily grouped into organics (includingpesticides, solvents, polychlorinatedbiphenyls (PCBs), and dioxins) and metals(including lead, silver, mercury, copper,chromium, zinc, nickel, and cadmium).

Nonconventional pollutants are anyadditional substances that are not con-sidered conventional or toxic that mayrequire regulation. These include nutri-ents such as nitrogen and phosphorus.


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National Pretreatment Program, EPA, states,and local regulatory agencies establish dis-charge limits to reduce the level of pollutantsdischarged by industry into municipal sewersystems. These limits control the pollutantlevels reaching a POTW, improve the qualityof the effluent and sludges produced by thePOTW, and increase the opportunity for ben-eficial use of the end products (e.g., effluents,sludges, etc). Further information aboutindustrial pretreatment and the NationalPretreatment Program is available on theOffice of Wastewater Management’s Web pageat <cfpub.epa.gov/npdes/home.cfm?program_id=3>.

POTWs are designed to treat domesticwastes and biodegradable commercial andindustrial wastes. The CWA and EPA definethe pollutants from these sources as “conven-tional pollutants” which includes those spe-cific pollutants that are expected to bepresent in domestic discharges to POTWs.Commercial and industrial facilities can,however, discharge toxic pollutants that atreatment plant is neither designed nor ableto remove. Such discharges, from both indus-trial and commercial sources, can cause seri-ous problems at POTWs. The undesirableoutcome of these discharges can be preventedby using treatment techniques or manage-ment practices to reduce or eliminate the dis-charge of these pollutants.

The act of treating wastewater prior to dis-charge to a POTW is commonly referred to as“pretreatment.” The National PretreatmentProgram provides the statutory and regulatorybasis to require non-domestic dischargers tocomply with pretreatment standards to ensurethat the goals of the CWA are attained. Theobjectives of the National PretreatmentProgram are to:

• Prevent the introduction of pollutantsinto POTWs which will interfere withthe operation of a POTW, including

interference with the disposal ofmunicipal sludge.

• Prevent the introduction of pollutantsinto POTWs which will pass throughthe treatment works or otherwise beincompatible with such works.

• Improve opportunities to recycle andreclaim municipal and industrialwastewaters and sludges.

To help accomplish these objectives, theNational Pretreatment Program is chargedwith controlling 126 priority pollutants fromindustries that discharge into sewer systemsas described in the CWA, Section 307(a), andlisted in 40 CFR Part 423 Appendix A. Thesepriority pollutants fall into two categories,metals and toxic organics.

• The metals include lead, mercury,chromium, and cadmium. Such toxicmetals cannot be destroyed or brokendown through treatment or environ-mental degradation. They can causevarious human health problems suchas lead poisoning and cancer.

• The toxic organics include solvents,pesticides, dioxins, and polychlorinat-ed biphenyls (PCBs). These can becancer-causing and lead to other seri-ous ailments, such as kidney and liverdamage, anemia, and heart failure.

The objectives of the NationalPretreatment Program are achieved by apply-ing and enforcing three types of dischargestandards: 1) prohibited discharge standards(provide for overall protection of POTWs), 2)categorical standards applicable to specificpoint source categories (provide for generalprotection of POTWs), and 3) local limits(address the water quality and other concernsat specific POTWs).

Prohibited Discharge Standards. Allindustrials users (IUs), whether or not subjectto any other federal, state, or local pretreat-


ment requirements, are subject to the generaland specific prohibitions identified in 40 CFRPart 403.5 (a) and (b), respectively. Generalprohibitions forbid the discharge of any pol-lutant to a POTW that can pass through orcause interference. Specific prohibitions for-bid the discharge of pollutants that pose fireor explosion hazards; corrosives; solid or vis-cous pollutants in amounts that will obstructsystem flows; quantities of pollutants that willinterfere with POTW operations; heat thatinhibits biological activity; specific oils; pollu-tants that can cause the release of toxic gases;and pollutants that are hauled to the POTW(except as authorized by the POTW).

Categorical Standards. Categorical pre-treatment standards are national, uniform,technology-based standards that apply to dis-charges to POTWs from specific industrialcategories (e.g., battery manufacturing, coilcoating, grain mills, metal finishing, petrole-um refining, rubber manufacturing) and limitthe discharge of specific pollutants. Thesestandards are described in 40 CFR Parts 405through 471.

Categorical pretreatment standards can beconcentration-based or mass-based.Concentration- based standards are expressedas milligrams of pollutant allowed per liter ofwastewater discharged (mg/l) and are issuedwhere production rates for the particularindustrial category do not necessarily corre-late with pollutant discharges. Mass-basedstandards are generally expressed as a massper unit of production (e.g., milligrams ofpollutant per kilogram of product produced)and are issued where production rates docorrelate with pollutant discharges. Thus,limiting the amount of water discharge (i.e.,water conservation) is important to reducingthe pollutant load to the POTW. For a fewcategories where reducing a facility’s flow vol-ume does not provide a significant differencein the pollutant load discharged, EPA has

established both mass- and concentration-based standards. Generally, both a daily maxi-mum limitation and a long-term averagelimitation (e.g., average daily values in a cal-endar month) are established for each regu-lated pollutant.

Local Limits. Federal regulations locatedat 40 CFR Parts 403.8 (f) (4) and 122.21 (j)(4) require authorities to evaluate the needfor local limits and, if necessary, implementand enforce specific limits protective of thatPOTW. Local limits might be developed forpollutants such as metals, cyanide, BOD, TSS,oil & grease, and organics that can interferewith or pass through the treatment works,cause sludge contamination, or cause workerhealth and safety problems if discharged atexcess levels.

All POTWs designed to accommodateflows of more than 5 million gallons per dayand smaller POTWs with significant industri-al discharges are required to establish pre-treatment programs. The EPA Regions andstates with approved pretreatment programsserve as approval authorities for the NationalPretreatment Program. In that capacity, theyreview and approve requests for POTW pre-treatment program approval or modification,oversee POTW program implementation,review requested modifications to categoricalpretreatment standards, provide technicalguidance to POTWs and IUs, and initiateenforcement actions against noncompliantPOTWs and IUs.

2. Treatment of Waste at POTWPlants

A waste treatment works’ basic function isto speed up the natural processes by whichwater is purified and returned to receivinglakes and streams. There are two basic stagesin the treatment of wastes, primary and sec-ondary. In the primary stage, solids are

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allowed to settle and are removed fromwastewater. The secondary stage uses biologi-cal processes to further purify wastewater.Sometimes, these stages are combined intoone operation. POTWs can also performother “advanced treatment” operations toremove ammonia, phosphorus, pathogensand other pollutants in order to meet effluentdischarge requirements.

Primary treatment. As sewage enters aplant for treatment, it flows through a screen,which removes large floating objects such asrags and sticks that can clog pipes or damageequipment. After sewage has been screened, itpasses into a grit chamber, where cinders,sand, and small stones settle to the bottom. Atthis point, the sewage still contains organicand inorganic matter along with other sus-pended solids. These solids are minute parti-cles that can be removed from sewage bytreatment in a sedimentation tank. When thespeed of the flow of sewage through one ofthese tanks is reduced, the suspended solidswill gradually sink to the bottom, where theyform a mass of solids called raw primarysludge. Sludge is usually removed from tanksby pumping, after which it can be furthertreated for use as fertilizer, or disposed ofthrough incineration if necessary. To completeprimary treatment, effluent from the sedimen-tation tank is usually disinfected with chlorinebefore being discharged into receiving waters.Sometimes chlorine is fed into the water tokill pathogenic bacteria and to reduceunpleasant odors.

Secondary treatment. The secondary stageof treatment removes about 85 percent of theorganic matter in sewage by making use of thebacteria in it. The two principal techniquesused in secondary treatment are trickling fil-ters and the activated sludge process.

Trickling filters. A trickling filter is a bed ofstones from three to six feet deep through

which the sewage passes. More recently, inter-locking pieces of corrugated plastic or othersynthetic media have also been used in trick-ling beds. Bacteria gather and multiply onthese stones until they can consume most ofthe organic matter in the sewage. The cleanerwater trickles out through pipes for furthertreatment. From a trickling filter, the sewageflows to another sedimentation tank toremove excess bacteria. Disinfection of theeffluent with chlorine is generally used tocomplete the secondary stage. Ultravioletlight or ozone are also sometimes used in sit-uations where residual chlorine would beharmful to fish and other aquatic life.

Activated sludge. The activated sludge treat-ment process speeds up the work of the bac-teria by bringing air and sludge, heavily ladenwith bacteria, into close contact with sewage.After the sewage leaves the settling tank inthe primary stage, it is pumped into an aera-tion tank, where it is mixed with air andsludge loaded with bacteria and allowed toremain for several hours. During this time,the bacteria break down the organic matterinto harmless by-products. The sludge, nowactivated with additional millions of bacteriaand other tiny organisms, can be used againby returning it to the aeration tank for mixingwith new sewage and ample amounts of air.From the aeration tank, the sewage flows toanother sedimentation tank to remove excessbacteria. The final step is generally the addi-tion of chlorine to the effluent.

Advanced treatment. New pollutionproblems have created additional treatmentneeds on wastewater treatment systems. Somepollutants can be more difficult to removefrom water. Increased demands on the watersupply only aggravate the problem. Thesechallenges are being met through better andmore complete methods of removing pollu-tants at treatment plants, or through preven-tion of pollution at the source (refer to


Chapter 3 – Integrating Pollution Preventionfor more information). Advanced waste treat-ment techniques in use or under develop-ment range from biological treatment capableof removing nitrogen and phosphorus tophysical-chemical separation techniques suchas filtration, carbon adsorption, distillation,and reverse osmosis. These wastewater treat-ment processes, alone or in combination, canachieve almost any degree of pollution con-trol desired. As waste effluents are purified tohigher degrees by such treatment, the effluentwater can be used for industrial, agricultural,or recreational purposes, or even as drinkingwater supplies.

III. UnderstandingFate andTransport ofPollutants

A. How Do PollutantsMove From WasteManagement Units ToSurface Water?

1. Overland FlowThe primary means by which pollutants

are transported to surface-water bodies is viaoverland flow or “runoff.” Runoff to surfacewater is the amount of precipitation after all“losses” have been subtracted. Losses includeinfiltration into soils, interception by vegeta-tion, depression storage and ponding, andevapotranspiration (i.e., evaporation from thesoil and transpiration by plants).

There is a correlation between the pollu-tant loadings to surface water and the amountof precipitation (rainfall, snow, etc.) that fallson the watershed in which a waste manage-ment unit is located. In addition, the charac-teristics of the soil at a facility also influencepollutant loading to surface water. If, forexample, the overland flow is diminished dueto high soil infiltration, so is the transport ofparticulate pollutants to surface water. Also, ifwastes are land applied and surface overlandflow is generated by a rainfall event, a signifi-cant portion of pollutants can be moved overland into adjacent surface water.

A diagram representing rainfall transforma-tion into runoff and other components of thehydrologic cycle is shown in Chapter 7:Section A–Assessing Risk. The first stage ofrunoff formation is condensation of atmos-pheric moisture into rain droplets orsnowflakes. During this process, water comesin contact with atmospheric pollutants. Thepollution content of rainwater can thereforereach high levels. In addition, rain water dis-

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What is “runoff?”

Runoff is water or leachate that drainsor flows over the land from any part of awaste management unit.

What is “run-on?”

Run-on is water from outside a wastemanagement unit that flows into theunit. Run-on includes storm water fromrainfall or the melting of snow or icethat falls directly on the unit, as well asthe water that drains from adjoiningareas.

solves atmospheric carbon dioxide and sulfurand nitrogen oxides, and acts as a weak acidafter it hits the ground, reacting with soil andlimestone formations. Overland flow beginsafter rain particles reach the earth’s surface(note that during winter months runoff for-mation can be delayed by snowpack forma-tion and subsequent melting). Rain hitting anexposed waste management unit will liberateand pick up particulates and pollutants fromthe unit and can also dissolve other chemicalsit comes in contact with. Precipitation thatflows into a waste management unit, called“run-on,” can also free-up and subsequentlytransport pollutants out of the unit. Runoffcarries the pollutants from the waste manage-ment unit as it flows downgradient followingthe natural contours of the watershed tonearby lakes, rivers, or wetland areas.

2. Ground Water to SurfaceWater

Ground water and surface water are funda-mentally interconnected. In fact, it is oftendifficult to separate the two because they“feed” each other. As a result, pollutants canmove from one media to another. Shallowwater table aquifers interact closely withstreams, sometimes discharging water into astream or lake and sometimes receiving waterfrom the stream or lake. Many rivers, lakes,and wetlands rely heavily on ground-waterdischarge as a source of water. During timesof low precipitation, some bodies of waterwould not contain any water at all if it werenot for ground-water discharge.

An unconfined aquifer that feeds a streamis said to provide the stream’s “baseflow.”Gravity is the dominant driving force inground-water movement in unconfinedaquifers. As such, under natural conditions,ground water moves “downhill” until it

reaches the land surface at a spring orthrough a seep in the side or bottom of ariver bed, lake, wetland, or other surface-water body. Ground water can also leave theaquifer via the pumping of a well. Theprocess of ground water outflowing into asurface-water body or leaving the aquiferthrough pumping is called discharge.

Discharge from confined aquifers occurs inmuch the same way except that pressure,rather than gravity, is the driving force inmoving ground water to the surface. Whenthe intersection between the aquifer and theland’s surface is natural, the pathway is calleda spring. If discharge occurs through a well,that well is a “flowing artesian well.”

3. Air to Surface WaterPollutants released into the air are carried

by wind patterns away from their place oforigin. Depending on weather conditions andthe chemical and physical properties of thepollutants, pollutants can be carried signifi-cant distances from their source and canundergo physical and chemical changes asthey travel. Some of these chemical changesinclude the formation of new pollutants suchas ozone, which is formed from nitrogenoxides (NOx) and hydrocarbons.

Atmospheric deposition occurs when pol-lutants in the air fall on the land or surfacewaters. When pollutants are deposited insnow, fog, or rain, the process is called wetdeposition, while the deposition of pollutantsas dry particles or gases is called dry deposi-tion. Pollutants can be deposited into waterbodies either directly from the air onto thesurface of the water, or through indirectdeposition, where the pollutants settle on theland and are then carried into a water bodyby runoff.


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Any pollutant that is emitted into the aircan become a surface-water problem due todeposition. Some of the common pollutantsthat can be transported to surface-water bod-ies via air include different forms of nitrogen,mercury, copper, polychlorinated biphenols(PCBs), polycyclic aromatic hydrocarbons(PAHs), chlordane, dieldrin, lead, lindane,polycyclic organic matter (POM), dioxins,and furans.

B. What Happens WhenPollutants Enter SurfaceWater?

All pollutants entering surface water viarunoff, ground-water infiltration, or air trans-port have an effect on the aquatic ecosystem.Additive and synergistic effects are also fac-tors because many different pollutants canenter a surface-water body from diversesources and activities. As such, solutions towater quality problems are best achieved bylooking at all activities and inputs to surfacewater in a watershed.

Surface-water ecosystems (i.e., rivers,lakes, wetlands, estuaries) are considered tobe in a dynamic equilibrium with their inputsand surroundings. These ecosystems can bedivided into two components, the biotic (liv-ing) and abiotic (nonliving). Pollutants arecontinually moving between the two. Forexample, pollutants can move from the abiot-ic environment (i.e., the water column) intoaquatic organisms, such as fish. The intake ofthe pollutant can occur as water moves acrossthe gills or directly through the skin. Toxicpollutants can accumulate in fish (known asbioaccumulation), as the fish uptakes more ofthe pollutant than it can metabolize orexcrete. Pollutants can eventually concentratein an organism to a level where death results.At that point, the pollutants will be released

back into the abiotic environment as theorganism decays.

Pollutants can also move within the abioticenvironment, as for example, between waterand its bottom sediments. Pollutants that areattached to soil particles being carried down-

The Dissolved OxygenProblem

The dissolved oxygen balance is animportant water quality considerationfor streams and estuaries. Dissolved oxy-gen is the most important parameter forprotecting fish and other aquatic organ-isms. Runoff with a high concentrationof biodegradable organics (organic mat-ter) can have a serious effect on theamount of dissolved oxygen in thewater. Low dissolved oxygen levels canbe very detrimental to fish. The contentof organic matter in waste discharges iscommonly expressed as the biochemicaloxygen demand (BOD) load. Organicmatter can come from a variety ofsources, including waste managementunits. When runoff containing organicmatter is introduced into receivingwaters, decomposers immediately beginto breakdown the organic matter usingdissolved oxygen to do so. Further, ifthere are numerous inputs of organicmatter into a single water body, forexample a stream, the effects will beadditive (i.e., more and more dissolvedoxygen will be removed from the streamas organic matter is added along thestream reach and decomposes). This isalso an example of how an input thatmight not be considered a pollutant(i.e., organic matter) can lead to harmfuleffects due to the naturally occurringprocess within a surface-water body.

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stream will be deposited on the bottom of thestreambed as the particles fall out of thewater column. In this manner, pollutants canaccumulate in areas of low flow. Thus, it isobvious that the hydrodynamical, biological,and chemical processes in aquatic systemscannot be separated and must be addressedsimultaneously when considering pollutantloads and impacts to surface water. Table 1presents some additional information on thebiological and chemical processes that occurin water bodies.

C. Pollutants Of ConcernAs you assess the different types of best

management practices (BMPs) that can beused at waste management units to protectsurface waters (discussed in Section IV of thischapter), you should also identify the pollu-tants in the unit that pose the greatest threatsto surface water. Factors to consider includethe solubility of the constituents in the wastemanagement unit, how easily these potentialpollutants can be mobilized, degradationrates, vapor pressures, and biochemical decaycoefficients of the pollutants and any otherfactors that could encourage their release intothe environment.

While all pollutants can become toxic athigh enough levels, there are a number ofcompounds that are toxic at relatively lowlevels. These pollutants have been designatedby the EPA as priority pollutants. The list ofpriority pollutants is included in Table 2. Thelist of priority pollutants is continuouslyunder review by EPA and is periodicallyupdated. The majority of pollutants on thelist are classified as organic chemicals. Othersare heavy metals which are being mobilizedinto the environment by human activities atrates greatly exceeding those of natural geo-logical processes. Several of the priority pol-lutants are also considered carcinogenic (i.e.,they can increase the risk of cancer to the

human population or to aquatic organisms,such as fish). Priority pollutants of particularconcern for surface-water bodies include:

• Metals, such as cadmium, copper,chromium, lead, mercury, nickel, andzinc, that arise from industrial opera-tions, mining, transportation, andagricultural use.

• Organic compounds, such as pesti-cides, PCBs, solvents, petroleumhydrocarbons, organometallic com-pounds, phenols, formaldehyde, andbiochemical methylation of metals inaquatic sediments.

• Dissolved gases, such as chlorine andammonium.

• Anions, such as cyanides, fluorides,sulfides, and sulphates.

• Acids and alkalis.

IV. ProtectingSurface Waters

A. Controls to AddressSurface-WaterContamination fromOverland Flow

Protecting surface water entails preventingstorm-water contamination during both theconstruction of a waste management unit andthe operational life of the unit. During con-struction the primary concern is sedimenteroding from exposed soil surfaces.Temporary sediment and erosion controlmeasures, such as silt fences around con-struction perimeters, straw bales aroundstorm-water inlets, and seeding or straw cov-ering of exposed slopes, are typically used tolimit and manage erosion. States or local


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Table 1. Biological and Chemical Processes Occurring in Surface-Water Bodies

After pollutants are transported to lakes, rivers, and other water bodies, they can be subject to avariety of biological and chemical processes that affect how they will interact and impact the aquat-ic ecosystem. These processes determine how pollutants are mobilized, degraded, or released intothe biotic and abiotic environments.

Metabolism of a toxicant consists of a series of chemical transformations that take place withinan organism. A wide range of enzymes act on toxicants, that can increase water solubility, and facil-itate elimination from the organism. In some cases, however, metabolites can be more toxic thantheir parent compound. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. GovernmentInstitutes.

Bioaccumulation is the uptake and sequestration of pollutants by organisms from their ambientenvironment. Typically, the concentration of the substance in the organism exceeds the concentra-tion in the environment since the organism will store the substance and not excrete it. Phillips.1993. In: Calow (ed), Handbook of Ecotoxicology, Volume One. Blackwell Scientific Publications.

Biomagnification is the concentration of certain substances up a food chain. It is a very impor-tant mechanism in concentrating pesticides and heavy metals in organisms such as fish. Certainsubstances such as pesticides and heavy metals move up the food chain, work their way into a riveror lake and are eaten by large birds, other animals, or humans. The substances become concentrat-ed in tissues or internal organs as they move up the chain. Sullivan. 1993. Environmental RegulatoryGlossary, 6th Ed. Government Institutes.

Biological degradation is the decomposition of a substance into more elementary compoundsby action of microorganisms such as bacteria. Sullivan. 1993. Environmental Regulatory Glossary, 6thEd. Government Institutes.

Hydrolysis is a chemical process of decomposition in which the elements of water react withanother substance to yield one or more new substances. This transformation process changes thechemical structure of the substance. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed.Government Institutes.

Precipitation is a chemical or physical change whereby a pollutant moves from a dissolved formin a solution to a solid or insoluble form and subsequently drops out of the solution. Precipitationreduces the mobility of constituents, such as metals and is not generally reversible. Boulding. 1995.Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and Remediation.

Oxidation/Reduction (Redox) process is a complex of biochemical reactions in sediment thatinfluences the valence state of elements (and their ions) found in sediments. Under anaerobic con-ditions the overall process shifts to a reducing condition. The chemical properties for elements canchange substantially with changes in the oxidation state. Sullivan. 1993. Environmental RegulatoryGlossary, 6th Ed. Government Institutes.

Photochemical process is the chemical changes brought about by the radiant energy of the sunacting upon various polluting substances. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed.Government Institutes.

001 Acenaphthene

002 Acrolein

003 Acrylonitrile

004 Benzene

005 Benzidine

006 Carbon tetrachloride

007 Chlorobenzene

008 1,2,4-trichlorobenzene

009 Hexachlorobenzene

010 1,2-dichloroethane

011 1,1,1-trichloreothane

012 Hexachloroethane

013 1,1-dichloroethane

014 1,1,2-trichloroethane

015 1,1,2,2-tetrachloroethane

016 Chloroethane

017 Bis(2-chloroethyl) ether

018 2-chloroethyl vinyl ethers

019 2-chloronaphthalene

020 2,4,6-trichlorophenol

021 Parachlorometa cresol

022 Chloroform

023 2-chlorophenol

024 1,2-dichlorobenzene



027 3,3-dichlorobenzidine

028 1,1-dichloroethylene

029 1,2-trans-dichloroethylene

030 2,4-dichlorophenol

031 1,2-dichloropropane

032 1,2-dichloropropylene

033 2,4-dimethylphenol

034 2,4-dinitrotoluene

035 2,6-dinitrotoluene

036 1,2-diphenylhydrazine

037 Ethylbenzene

038 Fluoranthene

039 4-chlorophenyl phenyl ether

040 4-bromophenyl phenyl ether

041 Bis(2-chloroisopropyl) ether

042 Bis(2-chloroethoxy) methane

043 Methylene chloride

044 Methyl chloride

045 Methyl bromide

046 Bromoform

047 Dichlorobromomethane

048 Chlorodibromomethane

049 Hexachlorobutadiene

050 Hexachlorocyclopentadiene

051 Isophorone

052 Naphthalene

053 Nitrobenzene

054 2-nitrophenol

055 4-nitrophenol

056 2,4-dinitrophenol

057 4,6-dinitro-o-cresol

058 N-nitrosodimethylamine

059 N-nitrosodiphenylamine

060 N-nitrosodi-n-propylamine

061 Pentachlorophenol

062 Phenol

063 Bis(2-ethylhexyl) phthalate

064 Butyl benzyl phthalate

065 Di-N-Butyl Phthalate

066 Di-n-octyl phthalate

067 Diethyl Phthalate

068 Dimethyl phthalate

069 Benzo(a) anthracene

070 Benzo(a)pyrene

071 Benzo(b) fluoranthene

072 Benzo(b) fluoranthene

073 Chrysene

074 Acenaphthylene

075 Anthracene

076 Benzo(ghi) perylene

077 Fluorene

078 Phenanthrene

079 Dibenzo(,h) anthracene

080 Indeno (1,2,3-cd) pyrene

081 Pyrene

082 Tetrachloroethylene

083 Toluene

084 Trichloroethylene

085 Vinyl chloride

086 Aldrin

087 Dieldrin

088 Chlordane

089 4,4-DDT

090 4,4-DDE

091 4,4-DDD

092 Alpha-endosulfan

093 Beta-endosulfan

094 Endosulfan sulfate

095 Endrin

096 Endrin aldehyde

097 Heptachlor

098 Heptachlor epoxide

099 Alpha-BHC

100 Beta-BHC

101 Gamma-BHC

102 Delta-BHC

103 PCB–1242

104 PCB–1254

105 PCB–1221

106 PCB–1232

107 PCB–1248

108 PCB–1260

109 PCB–1016

110 Toxaphene

111 Antimony

112 Arsenic

113 Asbestos

114 Beryllium

115 Cadmium

116 Chromium

117 Copper

118 Cyanide, Total

119 Lead

120 Mercury

121 Nickel

122 Selenium

123 Silver

124 Thallium

125 Zinc

126 2,3,7,8-TCDD


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3 The list of pollutants is current as of the Federal Register dated April 2, 2001.

Table 2. Priority Pollutants3

municipalities often require the use of sedi-ment and erosion controls at any construc-tion site disturbing greater than a certainnumber of acres, and can have additionalrequirements in especially sensitive water-sheds. You should consult with the state andlocal regulatory agencies to determine thesediment and erosion control requirementsfor construction.

Once a waste management unit has beenconstructed, permanent run-on and runoffcontrols are necessary to protect surfacewater. Run-on controls are designed to pre-vent storm water from entering the activeareas of units. If run-on is not preventedfrom entering active areas, it can seep intothe waste and increase the amount ofleachate that must be managed. It can alsodeposit pollutants from nearby sites, such aspesticides from adjoining farms, further bur-dening treatment systems. Excessive run-oncan also damage earthen containment sys-tems, such as dikes and berms. Run-on thatcontacts the waste can carry pollutants intoreceiving waters through overland runoff orinto ground water through infiltration. Youcan divert run-on to the waste managementunit by taking advantage of natural contoursin the land or by constructing ditches orberms designed to intercept and drain stormwater away from the unit. Run-on diversionsystems should be designed to handle thepeak discharge of a design storm event (e.g.,a 24-hour, 25-year storm4). Also note thatsurface impoundments should be designedwith sufficient freeboard and adequate capac-ity to accommodate not only waste, but alsoprecipitation and run-on.

Runoff controls can channel, divert, andconvey storm water to treatment facilities or,if appropriate, to other intended dischargepoints. Runoff from landfills, land treatmentunits, or waste piles should be managed as apotentially contaminated material. The runoff

from active areas of a landfill or waste pileshould be managed as leachate. You shoulddesign a leachate collection and removal sys-tem to handle the potentially contaminatedrunoff, in addition to the leachate that mightbe generated by the unit. You should segre-gate noncontact runoff to reduce the volumethat will need to be treated as leachate. TheMulti-Sector General Permit does not autho-rize discharges of leachate which includesstorm water that comes in contact withwaste. The discharge of leachate would beregulated under either an individually draftedNPDES permit with site- specific dischargelimitations, or an alternative NPDES generalpermit if one is available. Note that for landapplication sites, runoff from the site can alsoadversely affect nearby surface water if pollu-tants are picked up and carried overland.

BMPs are measures used to reduce oreliminate pollutant releases to surface watersvia overland flow. They fall into three cate-gories, baseline, activity-specific, and site-specific, and can take the form of a process,activity, or physical structure. The use of

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4 This discharge is the amount of water resulting from a 24-hour rainfall event of a magnitude with a 4percent statistical likelihood of occurring in any given year (i.e, once every 25 years). Such an eventmight not occur in a given 25-year period, or might occur more than once during a single year.


Why are “run-on” controls necessary?

Run-on controls are designed to pre-vent: 1) contamination of storm water,2) erosion that can damage the physicalstructure of units, 3) surface dischargeof waste constituents, 4) creation ofleachate, and 5) already contaminatedsurface water from entering the unit.

What is the purpose of a “runoff”control system?

Runoff control systems are designedto collect and control at a minimum thewater flow resulting from a storm eventof a specified duration, such as a 24-hour, 25-year storm event.

BMPs to protect surface water should be con-sidered in both the design and operation of awaste management unit. Before identifyingand implementing BMPs, you should assessthe potential sources of storm-water contami-nation including possible erosion and sedi-ment discharges caused by storm events. Athorough assessment of a waste managementunit involves several steps including creatinga map of the waste managementunit area; considering the designof the unit; identifying areaswhere spills, leaks, or dischargescould or do occur; inventoryingthe types of wastes contained inthe unit; and reviewing currentoperating practices (refer toChapter 8–Operating the WasteManagement System for moreinformation). Figure 1 illustratesthe process of identifying andselecting the most appropriateBMPs.

Designing a storm-watermanagement system to protectsurface water involves knowl-edge of local precipitation pat-terns, surrounding topographicfeatures, and geologic condi-tions. You should consider sam-pling runoff to ascertain thequantity and concentration ofpollutants being discharged.(Refer to the Chapter 9–Monitoring Performance formore information). Collectingand evaluating this type of infor-mation can help you to selectthe most appropriate BMPs toprevent or control pollutant dis-charges. The same considera-tions (e.g., types of wastes to becontained in the unit, precipita-tion patterns, local topographyand geology) should be made

while designing and constructing a new wastemanagement unit to ensure that the properbaseline, activity-specific, and site-specificBMPs are implemented and installed from thestart of operations. After assessing the poten-tial and existing sources of storm-water conta-mination, the next step is to select appropriateBMPs to address these contamination sources.


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Figure 1. BMP Identification and Selection Flow Chart

Recommended Steps

Adapted from U.S. EPA, 1992e.

Assessment Phase Develop a site mapInventory and describe exposed materials List significant spills and leaks Identify areas associated with industrial activity Test for nonstorm-water dischargesEvaluate monitoring/sampling data if appropriate

(see Chapter 9–Monitoring Performance)

BMP Identification Phase Operational BMPsSource control BMPsErosion and sediment control BMPsTreatment BMPsInnovative BMPs

Implementation Phase Implement BMPsTrain employees

Evaluation/Monitoring Phase Conduct semiannual inspection/BMP evaluation (see

Chapter 8–Operating the Waste Management System)Conduct recordkeeping Monitor surface water if appropriate Review and revise plan

1. Baseline BMPsThese practices are, for the most part,

inexpensive and relatively simple. They focuson preventing circumstances that could leadto surface-water contamination before it canoccur. Many industrial facilities already havethese measures in place for product loss pre-vention, accident and fire prevention, workerhealth and safety, or compliance with otherregulations (refer to Chapter 8–Operating theWaste Management System for more informa-tion). Baseline BMPs include the measuressummarized below.

Good housekeeping. A clean and orderlywork environment is an effective first steptoward preventing contamination of run-onand runoff. You should conduct an inventoryof all materials and store them so as to pre-vent leaks and spills and, if appropriate,maintain them in areas protected from pre-cipitation and other elements.

Preventive maintenance. A maintenanceprogram should be in place and shouldinclude inspection, upkeep, and repair of thewaste management unit and any measuresspecifically designed to protect surface water.

Visual inspections. Inspections of sur-face-water protection measures and wastemanagement unit areas should be conductedto uncover potential problems and identifynecessary changes. Areas deserving closeattention include previous spill locations;material storage, handling, and transfer areas;and waste storage, treatment, and disposalareas. Any problems such as leaks or spillsthat could lead to surface-water contamina-tion should be corrected as soon as practical.

Spill prevention and response. Generaloperating practices for safety and spill pre-vention should be established to reduce acci-dental releases that could contaminaterun-on and runoff. Spill response plans

should be developed to prevent any acciden-tal releases from reaching surface water.

Mitigation practices. These practices con-tain, clean-up, or recover spilled, leaked, orloose material before it can reach surfacewater and cause contamination. Other BMPsshould be considered and implemented toavoid releases, but procedures for mitigationshould be devised so that unit personnel canreact quickly and effectively to any releasesthat do occur. Mitigation practices includesweeping or shoveling loose waste intoappropriate areas of the unit; vacuuming orpumping spilled materials into appropriatetreatment or handling systems; cleaning upliquid waste or leachate using sorbents suchas sawdust; and applying gelling agents toprevent spilled liquid from flowing towardssurface water.

Training employees to operate, inspect,and maintain surface-water protection mea-sures is itself considered a BMP, as is keepingrecords of installation, inspection, mainte-nance, and performance of surface-water pro-tection measures. For more information onemployee training and record keeping, referto Chapter 8–Operating the WasteManagement System.

2. Activity-Specific BMPsAfter assessment and implementation of

baseline BMPs, you should also considerplanning for activity-specific BMPs. Likebaseline BMPs, they are often proceduralrather than structural or physical measures,and they are often inexpensive and easy toimplement. In the BMP manual for industrialfacilities, Storm Water Management forIndustrial Activities: Developing PollutionPrevention Plans and Best Management Practices(U.S. EPA, 1992f), EPA developed activity-specific BMPs for nine industrial activities,including waste management. The BMPs that

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are relevant to waste management are sum-marized below.

Preventing waste leaks and dust emis-sions due to vehicular travel. To preventleaks, you should ensure that trucks movingwaste into and around a waste managementunit have baffles (if they carry liquid waste)or sealed gates, spill guards, or tarpaulin cov-ers (if the waste is solid or semisolid). Tominimize tracking dust off site where it canbe picked up by storm water, wash trucks ina curbed truck wash area where wash wateris captured and properly handled. For moreinformation on these topics, consult Chapter8–Operating the Waste Management System .You should be aware that washwater fromvehicle and equipment cleaning is consideredto be “process wastewater,” and is not eligiblefor discharge under the Multi-Sector GeneralPermit program for industrial storm-waterdischarges. Such discharges would requirecoverage under either a site-specific individ-ual NPDES permit or an NPDES generalstorm-water permit.

For land application, choosing appropri-ate slopes. You should minimize runoff bydesigning a waste management unit site withslopes less than six percent. Moderate slopeshelp reduce storm-water runoff velocitywhich encourages infiltration and reduceserosion and sedimentation. Note that storm-water discharges from land application unitsare regulated under the Multi-Sector GeneralPermit program.

3. Site-Specific BMPsIn addition to baseline and activity-specific

BMPs, you should also consider site-specificBMPs, which are more advanced measurestailored to specific pollutant sources at a par-ticular waste management unit and usuallyconsist of the installation of structural orphysical measures. These site-specific BMPscan be grouped into five areas: flow diver-

sion, exposure minimization, erosion andsedimentation prevention, infiltration, andother prevention practices. For many of thesurface-water protection measures describedin this section, it is important to design for anappropriate storm event (i.e., structures thatcontrol run-on and runoff should be designedfor the discharge of a 24-hour, 25-year stormevent).

When selecting and designing surface-water protection measures or systems, youshould consult state, regional, and localwatershed management organizations. Someof these organizations maintain managementplans devised at the overall watershed levelthat address storm-water control. Thus, theseagencies might be able to offer guidance indeveloping surface-water protection systemsfor optimal coordination with other dis-charges in the watershed. Again, after site-specific BMPs have been installed, you shouldevaluate the effectiveness of the selectedBMPs on a regular basis to ensure that theyare functioning properly .


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BMP Maintenance

BMPs must be maintained on a regu-lar basis to ensure adequate surface-water protection. Maintenance isimportant because storms can damagesurface-water protection measures suchas storage basin embankments or spill-ways. Runoff can also cause sedimentsto settle in storage basins or ditches andcan carry floatables (i.e., tree branches,lumber, leaves, litter) to the basin.Facilities might need to repair storm-water controls and periodically removesediment and floatables.

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a. Flow Diversion

Flow diversion can be used to protect sur-face water in two ways. First, it can channelstorm water away from waste managementunits to minimize contact of storm waterwith waste. Second, it can carry polluted orpotentially polluted materials to treatmentfacilities. Flow diversion mechanisms includestorm-water conveyances and diversiondikes.

Storm-Water Conveyances (Channels, Gutters,Drains, and Sewers)

Storm-water conveyances, such as chan-nels, gutters, drains, and sewers, can preventstorm-water run-on from entering a wastemanagement unit or runoff from leaving aunit untreated. Some conveyances collectstorm water and route it around waste man-agement units or other waste containmentareas to prevent contact with the waste,which might otherwise contaminate stormwater with pollutants. Other conveyancescollect water that potentially came into con-tact with the waste management unit andcarry it to a treatment plant (or possibly backto the unit for reapplication in the case ofland application units, some surfaceimpoundments, and leachate-recirculatinglandfills). Conveyances should not mix thestream of storm water diverted around theunit with that of water that might have con-tacted waste. Remember, storm water thatcontacts waste is considered leachate and canonly be discharged in accordance with anNPDES permit other than the Multi-SectorGeneral Permit.

Storm-water conveyances can be con-structed of or lined with materials such asconcrete, clay tile, asphalt, plastic, metal,riprap, compacted soil, and vegetation. Thematerial used will vary depending on the useof the conveyance and the expected intensityof storm-water flow. Storm-water con-

veyances should be designed with a capacityto accept the estimated storm-water flowassociated with the selected design stormevent. Section V of this chapter discussesmethods for determining storm water flow.

Diversion Dikes

Diversion dikes, often made with compact-ed soil, direct run-on away from a waste man-agement unit. Dikes are built uphill from aunit and usually work with storm-water con-veyances to divert storm water from the unit.To minimize the potential for erosion, diver-sion dikes are often constructed to redirectrunoff at a shallow slope to minimize itsvelocity. A similar means of flow diversion isgrading the area around the waste manage-ment unit to keep storm water away from thearea, instead of or in addition to using diver-sion dikes to redirect water that would other-wise flow into these areas. In planning for theinstallation of dikes, you should consider theslope of the drainage area, the height of thedike, the size of the flow it will need to divert,

What are some advantages ofconveyances?

Conveyances direct storm-water flowsaround industrial areas, waste manage-ment units, or other waste containmentareas to prevent temporary flooding;require little maintenance; and providelong-term control of storm-water flows.

What are some disadvantages ofconveyances?

Conveyances require routing throughstabilized structures to minimize erosion.They also can increase flow rates, mightbe impractical if there are space limita-tions, and might not be economical.

and the type of conveyance that will be usedwith the dike.

b. Exposure Minimization

Like flow diversion, exposure minimiza-tion practices, such as curbing, diking, andcovering can reduce contact of storm waterwith waste. They often are small structuresimmediately covering or surrounding a high-er risk area, while flow diversion practicesoperate on the scale of an entire waste man-agement unit.

Curbing and Diking

These are raised borders enclosing areaswhere liquid spills can occur. Such areascould include waste transfer points in landapplication, truck washes, and leachate man-agement areas at landfills and waste piles.The raised dikes or curbs prevent spilled liq-uids from flowing to surface waters, enablingprompt cleanup of only a small area.

Covering

Erecting a roof, tarpaulin, or other perma-nent or temporary covering (see Figure 2)over the active area of a landfill or wastetransfer location can keep precipitation fromfalling directly on waste materials and pre-vent run-on from occurring. If temporarycoverings are used, you should ensure thatsufficient weight is attached to prevent windfrom moving the cover, and to repair orreplace the cover material if holes or leaksdevelop.

c. Erosion and SedimentationPrevention

Erosion and sedimentation practices serve tolimit erosion (the weathering of soil or rockparticles from the ground by wind, water, orhuman activity) and to prevent particles thatare eroded from reaching surface waters as sed-

iment. Erosion and sedimentation can threatenaquatic life, increase treatment costs for down-stream water treatment plants, and impederecreational and navigational uses of water-ways. Erosion and sedimentation are of particu-lar concern at waste management units becausethe sediment can be contaminated with wasteconstituents and because erosion can undercutor otherwise weaken waste containment struc-tures. Practices such as vegetation, interceptordikes, pipe slope drains, silt fences, storm draininlet protection, collection and sedimentationbasins, check dams, terraces and benches, andoutlet protection can help limit erosion andsedimentation.

Vegetation

Erosion and sedimentation can be reducedby ensuring that areas where storm water islikely to flow are vegetated. Vegetation slowserosion and sedimentation by shielding soilsurfaces from rainfall, improving the soil’swater storage capacity, holding soil in place,slowing runoff, and filtering out sediment.One method of providing vegetation is to pre-serve natural growth. This is achieved by


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What are some advantages ofdiversion dikes?

Diversion dikes limit storm-waterflows over industrial site areas; can beeconomical, temporary structures whenbuilt from soil onsite; and can be con-verted from temporary to permanent atany time.

What are some disadvantages ofdiversion dikes?

Diversion dikes are not suitable forlarge drainage areas unless there is agentle slope and might require mainte-nance after heavy rains.

managing the construction of the waste man-agement unit to minimize disturbance of sur-rounding grass and plants. If it is not possibleto leave all areas surrounding a unit undis-turbed, preserve strips of existing vegetationas buffer zones in strategically chosen areas ofthe site where erosion and sediment control ismost needed, such as on steep slopes uphillof the unit and along stream banks downhillfrom the unit. If it is not possible to leave suf-ficient buffer zones of existing vegetation, youshould create buffer zones by planting suchareas with new vegetation.

Temporary or permanent seeding of erodi-ble areas is another means of controlling ero-sion and sedimentation using vegetation.Permanent seeding, often of grass, is appro-priate for establishing long-term groundcover after construction and other land-dis-turbing activities are complete. Temporaryseeding can help prevent erosion and sedi-

mentation in areas that are exposed but willnot be disturbed again for a considerabletime. These areas include soil stockpiles,temporary roadbanks, and dikes. Local regu-lations might require temporary seeding ofareas that would otherwise remain exposedbeyond a certain period of time. You shouldconsult local officials to determine whethersuch requirements apply. Seeding might notbe feasible for quickly establishing cover inarid climates or during nongrowing seasonsin other climates. Sod, although more expen-sive, can be more tolerant of these conditionsthan seed and establish a denser grass covermore quickly. Compost used in combinationwith seeding can also be used effectively toestablish vegetation on slopes.

Physical and chemical stabilization, andvarious methods of providing cover are alsooften considered in conjunction with vegeta-tive measures or when vegetative measurescannot be used. Physical stabilization isappropriate where stream flow might beincreased due to construction or other activi-ties associated with the waste managementunit and where vegetative measures are notpractical. Stream-bank stabilization mightinvolve the reinforcement of stream bankswith stones, concrete or asphalt, logs, orgabions (i.e., structures formed from crushedrock encased in wire mesh). Methods of pro-viding cover such as mulching, compost, mat-ting, and netting can be used to coversurfaces that are steep, arid, or otherwiseunsuitable for planting. These methods alsocan work in conjunction with planting to sta-bilize and protect seeds. (Mattings are sheetsof mulch that are more stable than loosemulch chips. Netting is a mesh of jute, woodfiber, plastic, paper, or cotton that can holdmulch on the ground or stabilize soils. Thesemeasures are sometimes used with seeding toprovide insulation, protect against birds, andhold seeds and soil in place.) Chemical stabi-lization (also known as chemical mulch, soil

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Figure 2. Coverings

Roof, overhang, or other permanent structure

Tarp or other covering

From U.S. EPA, 1992e.

binder, or soil palliative) can hold the soil inplace and protect against erosion by sprayingvinyl, asphalt, or rubber onto soil surfaces.Erosion and sediment control is immediateupon spraying and does not depend on cli-mate or season. Stabilizer should be appliedaccording to manufacturer’s instructions toensure that water quality is not affected.Coating large areas with thick layers of stabi-lizer, however, can create an impervious sur-face and speed runoff to downgradient areasand should be avoided.

Interceptor Dikes and Swales

Dikes (ridges of compacted soil) andswales (excavated depressions in which stormwater flows) work together to prevent entryof run-on into erodible areas. A dike is builtacross a slope upgradient of an area to beprotected, such as a waste management unit,with a swale just above the dike. Water flowsdown the slope, accumulates in the swale,and is blocked from exiting it by the dike.The swale is graded to direct water slowlydownhill across the slope to a stabilized out-let structure. Since flows are concentrated inthe swale, it is important to vegetate theswale to prevent erosion of its channel and tograde it so that predicted flows will not dam-age the vegetation.

Pipe Slope Drains

Pipe slope drains are flexible pipes orhoses used to traverse a slope that is alreadydamaged or at high risk of erosion. They areoften used in conjunction with some meansof blocking water flow on the slope, such as adike. Water collects against the dike and isthen channeled to one point along the dikewhere it enters the pipe, which conveys itdownhill to a stabilized (usually riprap-lined)outlet area at the bottom of the slope. Youshould ensure that pipes are of adequate size

to accommodate the design storm event andare kept clear of clogs.

Silt Fences, Straw Bales, and Brush Barriers

Silt fences and straw bales (see Figures 3and 4) are temporary measures designed tocapture sediment that has already eroded andreduce the velocity of storm water. Silt fencesand straw bales should not be consideredpermanent measures unless fences are main-tained on a routine basis and straw bales arereplaced regularly. They could be used, forexample, during construction of a waste man-agement unit or on a final cover before per-manent grass growth is established.

Silt fences consist of geotextile fabric sup-ported by wooden posts. These fences slowthe flow of storm water and retain sediment asthe water filters through the fabric. If properlyinstalled, straw bales perform a similar func-tion. Straw bales should be placed end to end(with no gaps in between) in a shallow, exca-vated trench and staked into place. Silt fencesand straw bales limit sediment from enteringreceiving waters if properly maintained. Bothmeasures require frequent inspection andmaintenance, including checking for channelseroded beneath the fence or bales, removing


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What are some advantages of siltfences, straw bales, and brush barriers?

They prevent eroded materials fromreaching surface waters and preventdownstream damage from sedimentdeposits at minimal cost.

What are some disadvantages of siltfences, straw bales, and brush barriers?

These measures are not appropriatefor streams or large swales and pose arisk of washouts if improperly installed.

accumulated sediment, and replacing dam-aged or deteriorated sections.

Brush barriers work like silt fences andstraw bales but are constructed of readilyavailable materials. They consist of brush andother vegetative debris piled in a row and areoften covered with filter fabric to hold themin place and increase sediment interception.Brush barriers are inexpensive due to theirreuse of material that is likely available fromclearing the site. New vegetation often growsin the organic material of a brush barrier,helping anchor the barrier with roots.Depending on the material used, it might bepossible to leave a former brush barrier inplace and allow it to biodegrade, rather thanremove it.

Storm Drain Inlet Protection

Filtering measures placed around inlets ordrains to trap sediment are known as inletprotection (see Figure 5). These measuresprevent sediment from entering inlets ordrains and possibly making their way to thereceiving waters into which the stormdrainage system discharges. Keeping sedimentout of storm-water drainage systems alsoserves to prevent clogging, loss of capacity,and other problems associated with siltationof drainage structures. Inlet protection meth-ods include sod, excavated areas for settle-ment of sediment, straw bales or filter fences,and gravel or stone with wire mesh. Thesemeasures are appropriate for inlets drainingsmall areas where soil will be disturbed. Somestate or local jurisdictions require installationof these measures before disturbance of morethan a certain acreage of land begins. Regularmaintenance to remove accumulated sedi-ment is important for proper operation.

Collection and Sedimentation Basins

A collection or sedimentation basin (seeFigure 6) is an area that retains runoff long

enough to allow most of the sediment to set-tle out and accumulate on the bottom of thebasin. Since many pollutants are attached tosuspended solids, they will also settle out inthe basin with the sediment. The quantity ofsediment removed will depend on basin vol-ume, inlet and outlet configuration, basindepth and shape, and retention time. Regularmaintenance and dredging to remove accu-

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Figure 3. Silt Fence

Bottom: Perspective of silt fence. Top: Cross-

section detail of base of silt fence.


Figure 4. Straw Bale


mulated sediment and to minimize growth ofaquatic plants that can reduce effectiveness iscritical to the operation of basins. All dredgedmaterials, whether they are disposed orreused, should be managed appropriately.

Basins can also present a safety hazard.Fences or other measures to prevent unwant-ed public access to the basins and their associ-ated inlet and outlet structures are prudentsafety precautions. In designing collection orsedimentation basins (a form of surfaceimpoundment), consider storm- water flow,sediment and pollutant loadings, and thecharacteristics of expected pollutants. In thecase of certain pollutants, it might be appro-priate to line the basins to protect the groundwater below. Lining a basin with concrete alsofacilitates maintenance by allowing dredgingvehicles to drive into a drained basin andremove accumulated sediment. Poor imple-mentation of baseline and activity-specificBMPs can result in high sediment and pollu-tant loads, leading to unusually frequent

dredging of settled materials. For this reason,when operating sedimentation basins, it isimportant that baseline and activity-specificBMPs are being implemented properly. Werecommend that construction of these basinsbe supervised by a qualified engineer familiarwith state and local storm-water requirements.

Check Dams

Small rock or logdams erected across aditch, swale, or channelcan reduce the speed ofwater flow in the con-veyance. This reduceserosion and also allowssediment to settle outalong the channel. Checkdams are especially use-ful in steep, fast-flowingswales where vegetationcannot be established.For best results, it is rec-ommended that youplace check dams alongthe swale so that the crestof each check dam is atthe same elevation as thetoe (lowest point) of the


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Figure 5. Storm Drain Inlet Protection


What are some advantages ofsedimentation basins?

They protect downstream areas againstclogging or damage and contain smallersediment particles than sediment trapscan due to their longer retention time.

What are some disadvantages?

Sedimentation basins are generallynot suitable for large areas, require regu-lar maintenance and cleaning, and willnot remove very fine silts and claysunless used with other measures.

previous (upstream) check dam. Check damswork best in conveyances draining smallareas and should be installed only in man-made conveyances. Placement of check damsin streams is not recommended and mightrequire a permit.

Terraces and Benches

Terraces and benches are earthen embank-ments with flat tops or ridge-and-channels.Terraces and benches hold moisture andminimize sediment loading in runoff. Theycan be used on land with no vegetation orwhere it is anticipated that erosion will be aproblem. Terraces and benches reduce ero-sion damage by capturing storm-water runoffand directing it to an area where the runoffwill not cause erosion or damage. For bestresults, this area should be a grassy waterway,vegetated area, or tiled outlet. Terraces andbenches might not be appropriate for use onsandy or rocky slopes.

Outlet Protection

Stone, riprap, pavement, or other stabi-lized surfaces placed at a storm-water con-veyance outlet are known as outlet protection(see Figure 7). Outlet protection reduces thespeed of concentrated storm-water flows exit-ing the outlet, lessening erosion and scouringof channels downstream. It also removes sed-iment by acting as a filter medium. It is rec-ommended that you consider installing outletprotection wherever predicted outflow veloci-ties might cause erosion.

d. Infiltration

Infiltration measures such as vegetated fil-ter strips, grassed swales, and infiltrationtrenches encourage quick infiltration ofstorm water into the ground rather thanallowing it to remain as overland flow.Infiltration not only reduces runoff velocity,but can also provide some treatment ofrunoff, preserve natural stream flow, andrecharge ground water. Infiltration measurescan be inappropriate on unstable slopes or incases where runoff might be contaminated,

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Figure 6. Collection and Sedimentation Basin


What are some advantages of terracesand benches?

Terraces and benches reduce runoffspeed and increase the distance of over-land runoff flow. In addition, they holdmoisture better than do smooth slopesand minimize sediment loading in runoff.

What are some disadvantages ofterraces and benches?

Terraces and benches can significantlyincrease cut and fill costs and causesloughing if excess water infiltrates thesoil. They are not practical for sandy,steep, or shallow soils.

or where wells, foundations, or septic fieldsare nearby.

Vegetated Filter Strips and Grassed Swales

Vegetated filter strips are gently slopedareas of natural or planted vegetation. Theyallow water to pass over them in sheetflow(runoff that flows in a thin, even layer), infil-trate the soil, and drop sediment. Vegetatedfilter strips are appropriate where soils arewell draining and the ground-water table isdeep below the surface. They will not workeffectively on slopes of 15 percent or moredue to high runoff velocity. Strips should beat least 20 feet wide and 50 to 75 feet long ingeneral, and longer on steeper slopes. If pos-sible, it is best to leave existing natural vege-tation in place as filter strips, rather thanplanting new vegetation, which will not func-tion to capture eroded particles until itbecomes established.

Grassed swales function similarly to non-vegetated swales (discussed earlier in thischapter) except that grass planted along theswale bottom and sides will slow water flowand filter out sediment. Permeable soil inwhich the swale is cut encourages reductionof water volume through infiltration. Checkdams (discussed earlier in this chapter) aresometimes provided in grassed swales to fur-ther slow runoff velocity, increasing the rateof infiltration.

To optimize swale performance, it is bestto use a soil which is permeable but notexcessively so; very sandy soils will not holdvegetation well and will not form a stablechannel structure. It is also recommendedthat you grade the swale to a very gentleslope to maximize infiltration.

Infiltration Trenches

An infiltration trench (see Figure 8) is along, narrow excavation ranging from 3 to 12

feet deep. It is filled with stone to allow fortemporary storage of storm water in the openspaces between the stones. The water eventu-ally infiltrates the surrounding soil or is col-lected by perforated pipes in the bottom ofthe trench and conveyed to an outflow point.Such trenches can remove fine sediments and


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Figure 7. Outlet Protection


soluble pollutants. They should not be builtin relatively impervious soils, such as clay,that would prevent water from draining fromthe bottom of the trench; less than 3 feetabove the water table; in soil that is subjectto deep frost penetration; or at the foot ofslopes steeper than 5 percent. Infiltrationtrenches should not be used to handle conta-minated runoff. Runoff can be pretreatedusing a grass buffer/filter strip or treated inthe trench with filter fabric.

e. Other Practices

Additional practices exist that can helpprevent contamination of surface water suchas preventive monitoring, dust control, vehi-cle washing, and discharge to wetlands.Many of these practices are simple and inex-pensive to implement while others, such asmonitoring, can require more resources.

Preventive Monitoring

Preventive monitoring includes automaticand control systems, monitoring of opera-tions by waste management unit personnel,and testing of equipment. These processescan help to ensure that equipment functionsas designed and is in good repair so thatspills and leaks, which could contaminateadjacent surface waters, are minimized anddo not go undetected when they do occur.Some automatic monitoring equipment, suchas pressure gauges coupled with pressurerelief devices, can correct problems withouthuman intervention, preventing leaks orspills that could contaminate surface water ifallowed to occur. Other monitoring equip-ment can provide early warning of problemsso that personnel can intervene before leaksor spills occur. Systems that could contami-nate surface water if they failed and thatcould benefit from automatic monitoring orearly warning devices include leachatepumping and treatment systems, liquid waste

distribution and storage systems at landapplication units, and contaminated runoffconveyances.

Dust Control

In addition to being an airborne pollutant,dust can settle in areas where it can bepicked up by runoff or can be transported byair and deposited directly into surface waters.Dust particles can carry pollutants and canalso result in sedimentation of waterbodies.Several methods of dust control are availableto prevent this. These include irrigation,chemical treatments, minimization ofexposed soil areas, wind breaks, tillage, andsweeping. For further information on dustcontrol, consult Chapter 8–Operating theWaste Management System.

Vehicle Washing

Materials that accumulate on tires and othervehicle surfaces and then disperse across afacility are an important source of surface-water contamination. Vehicle washing removesmaterials such as dust and waste. Washing sta-tions can be located near waste transfer areasor near the waste management site exit.Pressurized water spray is usually sufficient toremove dust. Waste water from vehicle wash-ing operations should be contained and han-

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Figure 8. Infiltration Trench


dled appropriately. Discharge of such wastewater requires an NPDES permit other thanthe Multi-Sector General Permit.

Discharges to Wetlands

Discharge to constructed wetlands is amethod less frequently used and can involvecomplicated designs. The discharge of stormwater into natural wetlands, or the modifica-tion of wetlands to improve their treatmentcapacity, can damage a wetland ecosystemand, therefore, is subject to federal, state, andlocal regulations.

Constructed wetlands provide an alterna-tive to natural wetlands. A specially designedpond or basin, which is lined in some cases,is stocked with wetland plants that can con-trol sedimentation and manage pollutantsthrough biological uptake, microbial action,and other mechanisms. Together, theseprocesses often result in better pollutantremoval than would be expected from sedi-mentation alone. When designing construct-ed wetlands, you should consider 1) thatmaintenance might include dredging, similarto that required for sedimentation basins, 2)

provisions for a dry-weather flow to maintainthe wetlands, 3) measures to limit mosquitobreeding, 4) structures to prevent escape offloating wetland plants (such as waterhyacinths) into downstream areas where theyare undesirable, and 5) a program of harvest-ing and replacing plants.

B. Controls to AddressSurface-waterContamination fromGround Water toSurface Water

Generally, the use of liners and ground-water monitoring systems will reduce poten-tial contamination from ground water tosurface water. For more information on pro-tecting ground water, refer to Chapter 7:Sections A–Assessing Risk, SectionB–Designing and Installing Liners, andSection C–Designing a Land ApplicationProgram.

C. Controls to AddressSurface-waterContamination from Airto Surface Water

Emission control techniques for volatileorganic compounds (VOC) and particulatescan assist in reducing potential contaminationof surface water from air. Refer to Chapter5–Protecting Air Quality, for more informa-tion on air emission control techniques.


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What are some advantages ofconstructed wetlands?

Provide aesthetic as well as water qual-ity benefits and areas for wildlife habitat.

What are some disadvantages ofconstructed wetlands?

Discharges to wetlands might be sub-ject to multiple federal, state, and localregulations. In addition, constructedwetlands might not be feasible if land isnot available and might not be effectiveas a storm-water control measure untiltime has been allowed for substantialplant growth.

V. Methods ofCalculating Run-on andRunoff Rates

The design and operation of surface-waterprotection systems will be driven by antici-pated storm-water flow. Run-on and runoffflow rates for the chosen design storm eventshould be calculated in order to: 1) choosethe proper type of storm-water controls toinstall, and 2) properly design the controlsand size the chosen control measures to min-imize impacts to surface water. Controlsbased on too small a design storm event, orsized without calculating flows will not func-tion properly and can result in releases ofcontaminated storm water. Similarly, systemscan also be designed for too large a flow,resulting in unnecessary control and exces-sive costs.

The usual approach for sizing surface-water protection systems relies on the use ofstandardized “design storms.” A design stormis, in theory, representative of many recordedstorms and reflects the intensity, volume, andduration of a storm predicted to occur oncein a given number of years. In general, sur-face-water protection structures should bedesigned to handle the discharge from a 24-hour, 25-year storm event (i.e., a rainfallevent of 24 hours duration and of such amagnitude that it has a 4 percent statisticallikelihood of occurring in any given year).Figure 9 presents a typical intensity-duration-frequency curve for rainfall events.

The Hydrometeorological Design StudiesCenter (HDSC) at the National WeatherService has prepared Technical Paper 40,Rainfall Frequency Atlas of the United States forDurations From 30 Minutes to 24 Hours andReturn Periods From 1 to 100 Years (published

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Rational Method forCalculating Storm-WaterRunoff FlowQ = cia

where,

Q = peak flow rate (runoff), expressed incubic feet per second (cfs)*

c = runoff coefficient, unitless. The coeffi-cient c is not directly calculable, soaverage values based on experienceare used. Values of c range from 0 (allinfiltration, no runoff) to 1 (allrunoff, no infiltration). For example,flat lawns with sandy soil have a cvalue of 0.05 to 0.10, while concretestreets have a c value of 0.80 to 0.95.

i = average rainfall intensity, expressedin inches per hour, for the time ofconcentration, tc, which is a calcula-ble flow time from the most distantpoint in the drainage area to thepoint at which Q is being calculated.Once tc is calculated and a designstorm event frequency is selected, ican be obtained from rainfall inten-sity-duration-frequency graphs (seeFigure 9).

a = drainage area, expressed in acres.The drainage area is the expanse inwhich all runoff flows to the pointat which Q is being calculated.

* Examining the units of i and a wouldindicate that Q should be in units ofac-in/hr. However, since 1 ac-in/hr =1.008 cfs, the units are interchangeablewith a negligible loss of accuracy. Unitsof cfs are usually desired for subse-quent calculations.

in 1961). This document contains rainfallintensity information for the entire UnitedStates. Another HDSC document, NOAA Atlas2, Precipitation Frequency Atlas of the WesternUnited States (published in 1973) comes in 11volumes, one for each of the 11 westernmostof the contiguous 48 states. Precipitation fre-quency maps for the eleven western moststates are available on the Western RegionalClimate Center’s Web page at <www.wrcc.sage.dri.edu/ pcpnfreq.html>. HDSC is cur-rently assembling more recent data for someareas. Your state or local regulatory agencymight be able to provide data for your area.

Several methods are available to help youcalculate storm-water flows. The RationalMethod can be used for calculating runoff forareas of less than 200 acres. Another usefultool for estimating storm-water flows is theNatural Resource Conservation Service’s TR-55 software.5 TR-55 estimates runoff volumefrom accumulated rainfall and then appliesthe runoff volume to a simplified hydrographfor peak discharge total runoff estimations.

Computer models are also available to aidin the design of storm-water control systems.For example, EPA’s Storm WaterManagement Model (SWMM) is a compre-hensive model capable of simulating themovement of precipitation and pollutantsfrom the ground surface through pipe andchannel networks, storage treatment units,and finally to receiving water bodies. UsingSWMM, it might be possible to perform bothsingle-event and continuous simulation on

catchments having storm sewers and naturaldrainage, for prediction of flows, stages, andpollutant concentrations.

Some models, including SWMM, weredeveloped for purposes of urban storm-watercontrol system design, so it is important toensure that their methodology is applicable tothe design of industrial waste managementunits. As with all computer models, theseshould be used as part of the array of designtools, rather than as a substitute for carefulconsideration of the unit’s design by qualifiedprofessionals.


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5 TR-55, Urban Hydrology for Small Watersheds Technical Release 55, presents simplified procedures tocalculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required forfloodwater reservoirs. This software is suited for use in small and especially urbanizing watersheds. TR-55 can be downloaded from the National Resource Conservation Service at<www.wcc.nrcs.usda.gov/water/quality/common/tr55/tr55.html>.

Figure 9. Typical Intensity-Duration-

Frequency Curves

From WATER SUPPLY AND POLLUTION CON-TROL, 5th Edition, by Warren Viessman, Jr. andMark J. Hammer; Copyright (©) 1993 by HarperCollins College Publishers. Reprinted by permis-sion of Addison-Wesley Educational Publishers.

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Storm Water Management Model (SWMM). Simulates the movement of precipitationand pollutants from the ground surface through pipe and channel networks, storage treat-ment units, and receiving waters.

BASINS: A Powerful Tool for Managing Watersheds. A multi-purpose environmen-tal analysis system that integrates a geographical information system (GIS), national water-shed data, and state-of-the-art environmental assessment and modeling tools into onepackage.

Source Loading and Management Model (SLAMM). Explores relationships betweensources of urban runoff pollutants and runoff quality. It includes a wide variety of sourcearea and outfall control practices. SLAMM is strongly based on actual field observations,with minimal reliance on theoretical processes that have not been adequately documentedor confirmed in the field. SLAMM is mostly used as a planning tool, to better understandsources of urban runoff pollutants and their control.

Simulation for Water Resources in Rural Basins (SWRRB). Simulates hydrologic,sedimentation, and nutrient and pesticide transport in large, complex rural watersheds. Itcan predict the effect of management decisions on water, sediment, and pesticide yieldwith seasonable accuracy for ungauged rural basins throughout the United States.

Pollutant Routing Model (P-ROUTE). Estimates aqueous pollutant concentrations ona stream reach by stream reach flow basis, using 7Q10 or mean flow.

Enhanced Stream Water Quality Model (QUAL2E). Simulates the major reactions ofnutrient cycles, algal production, benthic and carbonaceous demand, atmospheric reaera-tion and their effects on the dissolved oxygen balance. It is intended as a water qualityplanning tool for developing total maximum daily loads (TMDLs) and can also be used inconjunction with field sampling for identifying the magnitude and quality characteristicsof nonpoint sources.


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You should conduct the following activities when designing or operating surface-waterprotection measures or systems in conjunction with waste management units.

■■■■ Comply with applicable National Pollutant Discharge Elimination System (NPDES),state, and local permitting requirements.

■■■■ Assess operating practices, identify potential pollutant sources, determine what con-stituents in the unit pose the greatest threats to surface water, and calculate storm-water runoff flows to determine the need for and type of storm-water controls.

■■■■ Choose a design storm event (e.g., a 24-hour, 25-year event) and obtain precipita-tion intensity data for that event to determine the most appropriate storm-water con-trol devices.

■■■■ Select and implement baseline and activity-specific BMPs, such as good housekeep-ing practices and spill prevention and response plans as appropriate for your wastemanagement unit.

■■■■ Select and establish site-specific BMPs, such as diversion dikes, collection and sedi-mentation basins, and infiltration trenches as appropriate for your waste manage-ment unit.

■■■■ Develop a plan for inspecting and maintaining the chosen storm-water controls; ifpossible, include these measures as part of the operating plan for the waste manage-ment unit.

Protecting Surface Water Activity List

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Dingman, S. 1994. Physical Hydrology. Prentice Hall.

Florida Department of Environmental Regulation. Storm Water Management: A Guide for Floridians.

Novotny, V., and H. Olem. 1994. Water Quality: Prevention, Identification, and Management of DiffusePollution. Van Nostrand Reinhold.

Pitt, R. 1988. Source Loading and Management Model: An Urban Nonpoint Source Water Quality Model(SLAMM). University of Alabama at Birmingham.

McGhee, T. 1991. McGraw-Hill Series in Water Resources and Environmental Engineering. 6th Ed.

Urbonas, B., and P. Stahre. 1993. Storm Water: Best Management Practices and Detention for Water Quality,Drainage, and CSO Management. PTR Prentice Hall.

U.S. EPA. 1999. Introduction to the National Pretreatment Program. EPA833-B-98-002.

U.S. EPA. 1998. Water Quality Criteria and Standards Plan–Priorities for the Future. EPA822-R-98-003.

U.S. EPA. 1995a. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage. EPA625-R-95-001.

U.S. EPA. 1995b. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage. EPA625-R-95-002.

U.S. EPA. 1995c. NPDES Storm Water Multi-Sector General Permit Information Package.

U.S. EPA. 1995d. Storm Water Discharges Potentially Addressed by Phase II of the National PollutantDischarge Elimination System Storm Water Program. Report to Congress. EPA833-K-94-002.

U.S. EPA. 1994a. Introduction to Water Quality Standards. EPA823-B-95-004.

U.S. EPA. 1994b. Project Summary: Potential Groundwater Contamination from Intentional and Non-Intentional Storm Water Infiltration. EPA600-SR-94-061.

U.S. EPA. 1994c. Storm Water Pollution Abatement Technologies. EPA 600-R-94-129.

Resources


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U.S. EPA. 1993a. Overview of the Storm Water Program. EPA833-F-93-001.

U.S. EPA. 1993b. NPDES Storm Water Program: Question and Answer Document, Volume 2. EPA833-F093-002B.

U.S. EPA. 1992a. An Approach to Improving Decision Making in Wetland Restoration and Creation.EPA600-R-92-150.

U.S. EPA. 1992b. NPDES Storm Water Program: Question and Answer Document, Volume 1. EPA833-F-93-002.

U.S. EPA. 1992c. NPDES Storm Water Sampling Guidance Document. EPA833-B-92-001.

U.S. EPA. 1992d. Storm Water General Permits Briefing. EPA833-E-93-001.

U.S. EPA. 1992e. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plansand Best Management Practices. EPA832-R-92-006.

U.S. EPA. 1992f. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plansand Best Management Practices. Summary Guidance. EPA833-R-92-002.

Viessman Jr., W., and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th Ed.

Washington State Department of Ecology. 1993. Storm Water Pollution Prevention Planning for IndustrialFacilities: Guidance for Developing Pollution Prevention Plans and Best Management Practices. WaterQuality Report. WQ-R-93-015. September.

Resources (cont.)

Part IVProtecting Ground-Water Quality

Chapter 7: Section AAssessing Risk

Contents

I. Assessing Risk ............................................................................................................................................7A-3

A. General Overview of the Risk Assessment Process ................................................................................7A-3

1. Problem Formulation ........................................................................................................................7A-3

2. Exposure Assessment ........................................................................................................................7A-4

3. Toxicity Assessment ..........................................................................................................................7A-5

4. Risk Characterization ........................................................................................................................7A-5

B. Ground-Water Risk................................................................................................................................7A-6

1. Problem Formulation ........................................................................................................................7A-6

2. Exposure Assessment ........................................................................................................................7A-7

3. Toxicity Assessment ........................................................................................................................7A-11

4.Risk Characterization........................................................................................................................7A-12

II. The IWEM Ground-Water Risk Evaluation ..........................................................................................7A-14

A. The Industrial Waste Management Evaluation Model (IWEM) ............................................................7A-15

1. Leachate Concentrations..................................................................................................................7A-16

2. Models Associated with IWEM........................................................................................................7A-16

3. Important Concepts for Use of IWEM ............................................................................................7A-18

B. Tier 1 Evaluations................................................................................................................................7A-22

1. How Are the Tier 1 Lookup Tables Used? ......................................................................................7A-23

2. What Do the Results Mean and How Do I Interpret Them? ............................................................7A-25

C. Tier 2 Evaluations................................................................................................................................7A-27

1. How is a Tier 2 Analysis Performed? ..............................................................................................7A-27

2. What Do the Results Mean and How Do I Interpret Them? ............................................................7A-32

D. Strengths and Limitations ....................................................................................................................7A-34

1. Strengths ........................................................................................................................................7A-34

2. Limitations ......................................................................................................................................7A-34

E. Tier 3: A Comprehensive Site-Specific Evaluation ..............................................................................7A-35

1. How is a Tier 3 Evaluation Performed?............................................................................................7A-35

Assessing Risk Activity List ........................................................................................................................7A-40

Resources ....................................................................................................................................................7A-41

Tables:

Table 1. Earth’s Water Resources ................................................................................................................7A-1

Table 2. Examples of Attenuation Processes ............................................................................................7A-10

Table 3. List of Constituents in IWEM with Maximum Contaminant Levels (MCLs) ..............................7A-13

Contents

Table 4. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - No Liner/In situ Soils ..7A-24

Table 5. Example of Tier 1 Summary Table for HBN-based LCTVs for Landfill - No Liner/In situ Soils 7A-25

Table 6. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - Single Clay Liner ...... 7A-25

Table 7. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - Composite Liner ........ 7A-25

Table 8. Input Parameters for Tier 2 ........................................................................................................7A-29

Table 9. A Sample Set of Site-Specific Data for Input to Tier 2 ................................................................7A-31

Table 10. Example of Tier 2 Detailed Summary Table - No Liner/In situ Soils ........................................7A-31

Table 11. Example of Tier 2 Detailed Summary Table - Single Clay Liner................................................7A-32

Table 12. Example Site-Specific Ground-water Fate and Transport Models..............................................7A-38

Table 13. ASTM Ground-Water Modeling Standards ..............................................................................7A-39

Figures:

Figure 1: Representation of Contaminant Plume Movement ......................................................................7A-5

Figure 2: Three Liner Scenarios Considered in the Tiered Modeling Approach for Industrial Waste Guidelines ......................................................................................................................7A-22

Figure 3: Using Tier 1 Lookup Tables ......................................................................................................7A-27

PPrrootteeccttiinngg GGrroouunndd WWaatteerr——Assessing Risk

7A-1

1 Surface water, in the form of lakes and rivers, is the other major drinking water source. Speidel, D., L.Ruedisili, and A. Agnew. 1988. Perspectives on Water: Uses and Abuses.

2 Excludes cooling water for steam-electric power plants. U.S. Geological Survey. 1998. Estimated Use ofWater in the United States in 1995.

Ground water isthe water foundin the soil androck that makeup the Earth’s

surface. Although it com-prises only about 0.69 per-cent of the Earth’s waterresources, ground water is ofgreat importance. It repre-sents about 25 percent offresh water resources, andwhen the largely inaccessiblefresh water in ice caps andglaciers is discounted,ground water is the Earth’slargest fresh waterresource—easily surpassinglakes and rivers, as shown in Table 1.Statistics about the use of ground water as adrinking water source underscore the impor-tance of this resource. Ground water is asource of drinking water for more than half ofthe people in the United States.1 In ruralareas, 97 percent of households rely onground water as their primary source ofdrinking water.

In addition to its importance as a domesticwater supply, ground water is heavily used byindustry and agriculture. It provides approxi-mately 37 percent of the irrigation water and 18

percent of the total water used by industry.2

Ground water also has other important environ-mental functions, such as providing recharge tolakes, rivers, wetlands, and estuaries.

Water beneath the ground surface occurs inan upper unsaturated (vadose) zone and adeeper saturated zone. The unsaturated zoneis the area above the water table where thesoil pores are not filled with water, althoughsome water might be present. The subsurfacearea below the water table where the poresand cracks are filled with water is called thesaturated zone. This chapter focuses on

Assessing RiskThis chapter will help you:

• Protect ground water by assessing risks associated with new waste

management units and tailoring management controls accordingly.

• Understand the three-tiered evaluation discussed in this chapter

that can be used to determine whether a liner system is necessary,

and if so, which liner system is recommended, or whether land

application is appropriate.

• Follow guidance on liner design and land application practices.

RReessoouurrccee PPeerrcceenntt ooff PPeerrcceenntt ooff TToottaall NNoonnoocceeaanniicc

Oceans 97.25 —

Ice caps and glaciers 2.05 74.65

Ground water and soil moisture 0.685 24.94

Lakes and rivers 0.0101 0.37

Atmosphere 0.001 0.036

Biosphere 0.00004 0.0015

Table 1.Earth’s Water Resources

Adapted from Berner, E.K. and R. Berner. 1987. The Global

Water Cycle: Geochemistry and Environment

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ground water in the saturat-ed zone, where mostground-water withdrawalsare made.

Because ground water is amajor source of water fordrinking, irrigation, andprocess water, many differentparties are concerned aboutground-water contamination,including the public; indus-try; and federal, state, andlocal governments. Manypotential threats to the quali-ty of ground water exist,such as the leaching of fertil-izers and pesticides, contam-ination from faulty oroverloaded septic fields, andreleases from industrial facil-ities, including waste man-agement units.

If a source of groundwater becomes contaminat-ed, remedial action andmonitoring can be costly.Remediation can requireyears of effort, or in somecircumstances, might betechnically infeasible. Forthese reasons, preventingground-water contaminationis important, or at least min-imizing impacts to groundwater by implementing con-trols tailored to the risksassociated with the waste.

This chapter addresses how ground-waterresources can be protected through the use ofa systematic approach of assessing potentialrisk to ground water from a proposed wastemanagement unit (WMU). It discusses assess-ing risk and the three-tiered ground-water riskassessment approach implemented in the

Industrial Waste Management EvaluationModel (IWEM), which was developed as partof this Guide. Additionally, the chapter dis-cusses the use of this tool and how to applyits results and recommendations. It is highlyrecommended that you also consult with yourstate regulatory agency, as appropriate. Morespecific information on the issues described in

GGrroouunndd WWaatteerr iinn tthhee HHyyddrroollooggiicc CCyyccllee

The hydrologic cycle involves the continuous movement ofwater between the atmosphere, surface water, and theground. Ground water must be understood in relation toboth surface water and atmospheric moisture. Most addi-tions (recharge) to ground water come from the atmospherein the form of precipitation, but surface water in streams,rivers, and lakes will move into the ground-water systemwherever the hydraulic head of the water surface is higherthan the water table. Most water entering the ground as pre-cipitation returns to the atmosphere by evapotranspiration.Most water that reaches the saturated zone eventuallyreturns to the surface by flowing to points of discharge,such as rivers, lakes, or springs. Soil, geology, and climatewill determine the amounts and rates of flow among theatmospheric, surface, and ground-water systems.

Lake

Runoff

Groundwater flow

Evaporation

Precipitation

Infiltration

Percolation

Runoff

UnsaturatedWell

Groundwater

Groundwater

Saturated

Water Table

Transpiration

Flow

Zone

Zone

to lakes and streams

this chapter is available in the companiondocuments to the IWEM software: User’sGuide for the Industrial Waste ManagementEvaluation Model (U.S. EPA, 2002b), andIndustrial Waste Management Evaluation Model(IWEM) Technical Background Document (U.S.EPA, 2002a).

I. Assessing Risk

A. General Overview of theRisk Assessment Process

Our ground-water resources are essentialfor biotic life on the planet. They also act as amedium for the transport of contaminantsand, therefore, constitute an exposure path-way of concern. Leachate from WMUs can bea source of ground-water contamination.Residents who live close to a WMU and whouse wells for water supply can be directlyexposed to waste constituents by drinking orbathing in contaminated ground water.Residents also can be exposed by inhalingvolatile organic compounds (VOCs) andsemi-volatile organic compounds (SVOCs)that are released indoors while using groundwater for showering or via soil gas migrationfrom subsurface plumes.

The purpose of this section is to providegeneral information on the risk assessmentprocess and a specific description of howeach of the areas of risk assessment is appliedin performing ground-water risk analyses.Greater detail on each of the steps in theprocess as they relate to assessing ground-water risk is provided in later sections of thischapter.

In any risk assessment, there are basicsteps that are necessary for gathering andevaluating data. This Guide uses a four-partprocess to estimate the likelihood of chemi-cals coming into contact with people now or

in the future, and the likelihood that suchcontact will harm these people. This processshows how great (or small) the risks mightbe. It also points to who is at risk, what iscausing the risk, and how certain one can beabout the risks. A general overview of thesesteps is presented below to help explain howthe process is used in performing the assess-ments associated with IWEM. The compo-nents of a risk assessment that are discussedin this section are: problem formulation,exposure assessment, toxicity assessment, andrisk characterization. Each of these steps isdescribed as it specifically applies to riskresulting from the release of chemical con-stituents from WMUs to ground water.

1. Problem FormulationThe first step in the risk assessment

process is problem formulation. The purposeof this step is to clearly define the risk ques-tion to be answered and identify the objec-tives, scope, and boundaries of theassessment. This phase can be viewed asdeveloping the overall risk assessment studydesign for a specific problem. Activities thatmight occur during this phase include:

• Articulating a clear understanding ofthe purpose and intended use of therisk assessment.

• Identifying the constituents of concern.

• Identifying potential release scenarios.

• Identifying potential exposure path-ways.

• Collecting and reviewing availabledata.

• Identifying data gaps.

• Recommending data collectionefforts.

• Developing a conceptual model ofwhat is occurring at the site.


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Although this step can be formal or infor-mal, it is critical to the development of a suc-cessful assessment that fully addresses theproblem at hand. In addition, the develop-ment of a conceptual model helps direct thenext phases of the assessment and provides aclear understanding of the scope and designof the assessment.

2. Exposure AssessmentThe goals of an exposure assessment are

to: 1) characterize the source, 2) characterizethe physical setting of the area that containsthe WMU, 3) identify potential exposurepathways, 4) understand the fate and trans-port of constituents of concern, and 5) calcu-late constituent doses.

Source characterization involves definingcertain key parameters for the WMU. Theaccuracy of predicting risks improves as moresite-specific information is used in the char-acterization. In general, critical aspects of thesource (e.g., type of WMU, size, location,potential for leachate generation, and expect-ed constituent concentrations in leachate)should be obtained. Knowledge of the overallcomposition of the waste deposited in theWMU and of any treatment processes occur-ring in the WMU is important to determinethe overall characteristics of the leachate thatwill be generated.

The second step in evaluating exposure isto characterize the site with respect to itsphysical characteristics, as well as those ofthe human populations near the site.Important site characteristics include climate,meteorology, geologic setting, and hydrogeol-ogy. Consultation with appropriate technicalexperts (e.g., hydrogeologists, modelers)might be needed to characterize the site.Characterizing the populations near the sitewith respect to proximity to the site, activitypatterns, and the presence of sensitive sub-groups might also be appropriate. This group

of data will be useful in determining thepotential for exposure to and intake of con-stituents.

The next step in this process includesidentifying exposure pathways throughground water and estimating exposure con-centrations at the well3. In modeling themovement of the constituents away from theWMU, the Guide generally assumes that theconstituents behave as a plume (see Figure1), and the plume’s movement is modeled toproduce estimated concentrations of con-stituents at points of interest. As shown inFigure 1, the unsaturated zone receivesleachate from the WMU. In general, the flowin the unsaturated zone tends to be gravity-driven, although other factors (e.g., soilporosity, capillarity, moisture potential) canalso influence downward flow.

Transport through the unsaturated zonedelivers constituents to the saturated zone, oraquifer. Once the contaminant arrives at thewater table, it will be transported downgradi-ent toward wells by the predominant flowfield in the saturated zone. The flow field isgoverned by a number of hydrogeologic andclimate-driven factors, including regionalhydraulic gradient, hydraulic conductivity ofthe saturated zone, saturated zone thickness,local recharge rate (which might already beaccounted for in the regional hydraulic gradi-ent), and infiltration rate through the WMU.

The next step in the process is to estimatethe exposure concentrations at a well. Manyprocesses can occur in the unsaturated zoneand in the saturated zone that can influencethe concentrations of constituents in leachatein a downgradient well. These processesinclude dilution and attenuation, partitioningto solid, hydrolysis, and degradation.Typically, these factors should be consideredwhen estimating the expected constituentconcentrations at a receptor.

3 In this discussion and in IWEM, the term “well” is used to represent an actual or hypothetical ground-water monitoring well or drinking water well, located downgradient from a WMU.


7A-5

The final step in this process is estimatingthe dose. The dose is determined based onthe concentration of a constituent in a medi-um and the intake rate of that medium forthe receptor. For example, the dose is depen-dent on the concentration of a constituent ina well and the ingestion rate of ground waterfrom that well by the receptor. The intakerate is dependent on many behavior patterns,including ingestion rate, exposure duration,and exposure frequency. In addition, a riskassessor should consider the various routes ofexposure (e.g., ingestion, inhalation) to deter-mine a dose.

After all of this information has been col-lected, the exposure pathways at the site canbe characterized by identifying the potentiallyexposed populations, exposure media, expo-sure points, and relevant exposure routes andthen calculating potential doses.

3. Toxicity AssessmentThe purpose of a toxicity assessment is to

weigh available evidence regarding the poten-tial for constituents to cause adverse effects in

exposed individuals. It is also meant to pro-vide, where possible, an estimate of the rela-tionship between the extent of exposure to aconstituent and the increased likelihoodand/or severity of adverse effects. The intentis to establish a dose-response relationshipbetween a constituent concentration and theincidence of an adverse effect. It is usually afive-step process that includes: 1) gatheringtoxicity information for the substances beingevaluated, 2) identifying the exposure periodsfor which toxicity values are necessary, 3)determining the toxicity values for noncar-cinogenic effects, 4) determining the toxicityvalues for carcinogenic effects, and 5) sum-marizing the toxicity information. The deriva-tion and interpretation of toxicity valuesrequires toxicological expertise and shouldnot be undertaken by those without trainingand experience. It is recommended that youcontact your state regulatory agency for morespecific guidance.

4. Risk CharacterizationThis step involves summarizing and inte-

grating the toxicity and exposure assessments

Figure 1: Representation of Contaminant Plume Movement

Waste Management Unit

C

UnsaturatedZone

SaturatedZone Leachate Plume

DAF

Leachate

Well

Land Surface

Water Table

7A-6


and developing qualitative and quantitativeexpressions of risk. To characterize noncar-cinogenic effects, comparisons are madebetween projected intakes of substances andtoxicity values to predict the likelihood thatexposure would result in a non-cancer healthproblem, such as neurological effects. To char-acterize potential carcinogenic effects, theprobability that an individual will developcancer over a lifetime of exposure is estimatedfrom projected intake and chemical-specificdose-response information. The dose of a par-ticular contaminant to which an individualwas exposed—determined during the expo-sure assessment phase—is combined with thetoxicity value to generate a risk estimate.Major assumptions, scientific judgements,and, to the extent possible, estimates of theuncertainties embodied in the assessment arealso presented. Risk characterization is a keystep in the ultimate decision-making process.

B. Ground-Water RiskThe previous section provided an overview

of risk assessment; this section provides moredetailed information on conducting a riskassessment specific to ground water. In partic-ular, this section characterizes the phases of arisk assessment—problem formulation, expo-sure assessment, toxicity assessment, and riskcharacterization—in the context of a ground-water risk assessment.

1. Problem FormulationThe intent of the problem formulation

phase is to define the risk question to beanswered. For ground-water risk assessments,the question often relates to whether releasesof constituents to the ground water are pro-tective of human health, surface water, orground-water resources. This section discuss-es characterizing the waste and developing aconceptual model of a site.

a. Waste Characterization

A critical component in a ground-waterrisk assessment is the characterization of theleachate released from a WMU. Leachate isthe liquid formed when rain or other watercomes into contact with waste. The character-istics of the leachate are a function of thecomposition of the waste and other factors(e.g., volume of infiltration, exposure to dif-fering redox conditions, management of theWMU). Waste characterization includes bothidentification of the potential constituents inthe leachate and understanding the physicaland chemical properties of the waste.

Identification of the potential constituentsin leachate requires a thorough understandingof the waste that will be placed in a WMU.Potential constituents include those used intypical facility processes, as well as degrada-tion products from these constituents. Forground-water risk analyses, it is important tonot only identify the potential constituents ofconcern in the leachate, but also the likelyconcentration of these constituents in leachate.To assist in the identification of constituentspresent in leachate, EPA has developed severalleachate tests including the ToxicityCharacteristic Leaching Procedure (TCLP), theSynthetic Precipitation Leaching Procedure(SPLP), and the Multiple Extraction Procedure(MEP). These and other tests that can be usedto characterize leachate are discussed morefully in Chapter 2—Characterizing Waste andare described in EPA’s SW-846 Test Methods forEvaluating Solid Wastes (U.S. EPA, 1996 and asupdated).

In addition to identifying the constituentspresent, waste characterization includesunderstanding the physical, biological, andchemical properties of the waste. The physicaland chemical properties of the waste streamaffect the likelihood and rate that constituentswill move through the WMU. For example,the waste properties influence the partitioning


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4 Generally, the model considers a high ratio of solids to leachate, and therefore, the user should considerthis before applying a 20 to 1 solids to leachate ratio.

of constituents among the aqueous, vapor,and solid phases. Temperature, pH, pressure,chemical composition,4 and the presence ofmicroorganisms within WMUs may have sig-nificant effects on the concentration of con-stituents available for release in the leachate.Another waste characteristic that can influ-ence leachate production is the presence oforganic wastes as free liquids, also callednon-aqueous phase liquids (NAPLs). Thepresence of NAPLs may affect the mobility ofconstituents based on saturation and viscosi-ty. Finally, characteristics such as acidity andalkalinity can influence leachate generationby affecting the permeability of underlyingsoil or clay.

b. Development of a ConceptualModel

The development of a conceptual model isimportant for defining what is needed for theexposure assessment and the toxicity assess-ment. The conceptual model identifies themajor routes of exposure to be evaluated andpresents the current understanding of thetoxicity of the constituents of concern.

For the ground-water pathway, the concep-tual model identifies those pathways onwhich the risk assessor should focus.Potential pathways of interest include groundwater used as drinking water, ground waterused for other domestic purposes that mightrelease volatile organics, ground-water releas-es to surface water, vapor intrusion fromground-water gases to indoor air, and groundwater used as irrigation water. The conceptu-al model should address the likelihood ofvarious ground-water pathways under presentor future circumstances, provide insight tothe likelihood of contact with receptorsthrough the various pathways, and identifyareas requiring further information.

The conceptual model should also addressthe toxicity of the constituents of concern.

Information about constituent toxicity can becollected from publicly available resourcessuch as the Integrated Risk InformationSystem (IRIS) <www.epa.gov/iris> or fromdetailed, chemical-specific literature searches.The conceptual model should attempt toidentify the toxicity data that are most rele-vant to likely routes of ground-water expo-sure and identify areas requiring additionalresearch. The conceptual model should pro-vide a draft plan of action for the next phasesof the risk assessment.

2. Exposure AssessmentExposure assessment is generally com-

prised of two components: characterization ofthe exposure setting and identification of theexposure pathways. Characterization of theexposure setting includes describing thesource characteristics and the site characteris-tics. Identification of the exposure pathwayinvolves understanding the process by whicha constituent is released from a source, travelsto a receptor, and is taken up by the receptor.This section discusses the concepts of charac-terizing the source, characterizing the site set-ting, understanding the general dynamics ofcontaminant fate and transport (or movementof harmful chemicals to a receptor), identify-ing exposure pathways, and calculating thedose to (or uptake by) a receptor.

a. Source Characterization

The characteristics of a source greatlyinfluence the release of leachate to groundwater. Some factors to consider include thetype of WMU, the size of the unit, and thedesign and management of the unit. The typeof WMU is important because each unit hasdistinct characteristics that affect release.Landfills, for example, tend to be permanentin nature, which provides a long time periodfor leachate generation. Waste piles, on theother hand, are temporary in design and

allow the user to remove the source of conta-minated leachate at a future date. Surfaceimpoundments, which are generally managedwith standing water, provide a constantsource of liquid for leachate generation andpotentially result in greater volumes ofleachate.

The size of the unit is important becauseunits with larger areas have the potential togenerate greater volumes of contaminatedleachate than units with smaller areas. Also,units such as landfills that are designed with agreater depth below the ground’s surface canresult in decreased travel time from the bot-tom of the unit to the water table, resulting inless sorption of constituents. In some cases, aunit might be hydraulically connected withthe water table resulting in no attenuation inthe unsaturated zone.

The design of the unit is important becauseit might include an engineered liner systemthat can reduce the amount of infiltrationthrough the WMU, or a cover that can reducethe amount of water entering the WMU.Typical designs might include compacted clayliners or geosynthetic liners. For surfaceimpoundments, sludge layers from compactedsediments might also help reduce the amountof leachate released. The compacted sedi-ments can have a lower hydraulic conductivi-ty than the natural soils resulting in slowermovement of leachate from the bottom of theunit. Covers also affect the rate of leachategeneration by limiting the amount of liquidthat reaches the waste, thereby limiting theamount of liquid available to form leachate.Co-disposal of different wastes can result inincreased or decreased rates of leachate gener-ation. Generally, WMUs with appropriatedesign specifications can result in reducedleachate generation.

b. Site Characterization

Site characterization addresses the physicalcharacteristics of the site as well as the popu-lations at or near the site. Important physicalcharacteristics include the climate, geology,hydrology, and hydrogeology. These physicalcharacteristics help define the likelihood thatwater might enter the unit and the likelihoodthat leachate might travel from the bottom ofthe unit to the ground water. For example,areas of high rainfall are more likely to gener-ate leachate than arid regions. The geology ofthe site also can affect the rate of infiltrationthrough the unsaturated zone. For example,areas with fractured bedrock can allowleachate through more quickly than a packedclay material with a low hydraulic conductivi-ty. Hydrology should also be consideredbecause ground water typically discharges tosurface water. The presence of surface waterscan restrict flow to wells or might requireanalysis of the impact of contaminated groundwater on receptors present in the surfacewater. Finally, factors related to the hydrogeol-ogy, such as the depth to the water table, alsoinfluence the rate at which leachate reachesthe water table.

The characterization of the site also includesidentifying and characterizing populations ator near the site. When characterizing popula-tions, it is important to identify the relativelocation of the populations to the site. Forexample, it is important to determine whetherreceptors are downgradient from the unit andthe likely distance from the unit to wells. It isalso important to determine typical activitypatterns, such as whether ground water isused for drinking water or agricultural purpos-es. The presence of potential receptors is criti-cal for determining a complete exposurepathway. People might not live there now, butthey might live there in 50 years, based onfuture use assumptions. State or local agencieshave relevant information to help you identify

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areas that are designated as potential sourcesof underground drinking water.

c. Understanding Fate and Transport

In general, the flow in the unsaturated zonetends to be gravity-driven. As shown in Figure1, the unsaturated zone receives leachate infil-tration from the WMU. Therefore, the verticalflow component accounts for most of the fluidflux between the base of the WMU and thewater table. Water-borne constituents are car-ried vertically downward toward the watertable by the advection process. Mixing andspreading occur as a result of hydrodynamicdispersion and diffusion. Transport processesin the saturated zone include advection,hydrodynamic dispersion, and sorption.Advection is the process by which con-stituents are transported by the motion of theflowing ground water. Hydrodynamic disper-sion is the tendency for some constituents tospread out from the path that they would beexpected to flow. Sorption is the process bywhich leachate molecules adhere to the sur-face of individual clay, soil, or sediment parti-cles. Attenuation of some chemicals in theunsaturated zone is attributable to variousbiochemical or physicochemical processes,such as degradation and sorption.

The type of geological material below theunit affects the rate of movement because ofdifferences in hydraulic and transport proper-ties. One of the key parameters controllingcontaminant migration rates is hydraulic con-ductivity. The larger the hydraulic conductivi-ty, the greater the potential migration rate dueto lower hydraulic resistance of the formation.Hydraulic conductivity values of some hydro-geologic environments, such as bedded sedi-mentary rock aquifers, might not be as largeas those of other hydrogeologic environments,such as sand and gravel or fractured lime-stone. As a general principle, more rapid

movement of waste constituents can beexpected through coarse-textured materials,such as sand and gravel, than through fine-textured materials, such as silt and clay. Otherkey flow and transport parameters includedispersivity (which determines how far aplume will spread horizontally and verticallyas it moves away from the source) and porosi-ty (which determines the amount of porespace in the geologic materials in the unsatu-rated and saturated zone used for flow andtransport and can affect transport velocity).

As waste constituents migrate through theunsaturated and saturated zones, they canundergo a number of biochemical andphysicochemical processes that can lead to areduction in concentration of potentialground-water contaminants. These processesare collectively referred to as attenuationprocesses. Attenuation processes can removeor degrade waste constituents through filtra-tion, sorption, precipitation, hydrolysis, bio-logical degradation, bio-uptake, and redoxreactions. Some of these processes (e.g.,hydrolysis, biological degradation) can actual-ly result in the formation of different chemi-cals and greater toxicity. Attenuationprocesses are dependent upon several factors,including ground-water pH, ground-watertemperature, and the presence of other com-pounds in the subsurface environment. Table2 provides additional information on attenua-tion processes.

d. Exposure Pathways

A complete exposure pathway usually con-sists of four elements: 1) a source and mecha-nism of chemical release, 2) a retention ortransport medium (in this case, groundwater), 3) a point of potential human contactwith the contaminated medium (often referredto as the exposure point), and 4) an exposureroute (e.g., ingestion). Residents who live near

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a site might use ground water for their watersupply, and thus, the exposure point would bea well. Exposure routes typical of residentialuse of contaminated ground water includedirect ingestion through drinking water, der-mal contact while bathing, and inhalation ofVOCs during showering or from other house-hold water uses (e.g., dishwashers).

Another potential pathway of concern isexposure to ground-water constituents fromthe intrusion of vapors of VOCs and SVOCsthrough the basements and concrete slabs

beneath houses. This pathway is character-ized by the vapors seeping into householdsthrough the cracks and holes in basementsand concrete slabs. In some cases, concentra-tions of constituents can reach levels that pre-sent chronic health hazards. Factors that cancontribute to the potential for vapor intrusioninclude the types of constituents present inthe ground water, the presence of pavementor frozen surface soils (which result in highersubsurface pressure gradients and greatertransport), and the presence of subsurface

Biological degradation: Decomposition of a substance into more elementary compounds by actionof microorganisms such as bacteria. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed.Government Institutes.

Bio-uptake: The uptake and (at least temporary) storage of a chemical by an exposed organism. Thechemical can be retained in its original form and/or modified by enzymatic and non-enzymatic reac-tions in the body. Typically, the concentrations of the substance in the organism exceed the concentra-tions in the environment since the organism will store the substance and not excrete it. Sullivan. 1993.Environmental Regulatory Glossary, 6th Ed. Government Institutes.

Filtration: Physical process whereby solid particles and large dissolved molecules suspended in afluid are entrapped or removed by the pore spaces of the soil and aquifer media. Boulding, R. 1995.Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and Remediation.

Hydrolysis: A chemical process of decomposition in which the elements of water react with anothersubstance to yield one or more entirely new substances. This transformation process changes the chem-ical structure of the substance. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. GovernmentInstitutes.

Oxidation/Reduction (Redox) reactions: Involve a transfer of electrons and, therefore, a change inthe oxidation state of elements. The chemical properties for elements can change substantially withchanges in the oxidation state. U.S. EPA. 1991. Site Characterization for Subsurface Remediation.

Precipitation: Chemical or physical change whereby a contaminant moves from a dissolved form ina solution to a solid or insoluble form. It reduces the mobility of constituents, such as metals. Unlikesorption, precipitation is not generally reversible. Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and Remediation.

Sorption: The ability of a chemical to partition between the liquid and solid phase by determiningits affinity for adhering to other solids in the system such as soils or sediments. The amount of chemi-cal that "sorbs" to solids is dependent upon the characteristics of the chemical, the characteristics of thesurrounding soils and sediments, and the quantity of the chemical. Sorption generally is reversible.Sorption often includes both adsorption and ion exchange.

Table 2:

Examples of Attenuation Processes

gases such as methane that affect the rate oftransport of other constituents. Because of thecomplexity of this pathway and the evolvingscience regarding this pathway, IWEM focuseson the risks and pathways associated withresidential exposures to contaminated groundwater. If exposure through this route is likely,the user might consider Tier 3 modeling toassess this pathway. EPA is planning to issue areference document regarding the vaporintrusion pathway in the near future.

e. Dose Calculation

The final element of the exposure assess-ment is the dose calculation. The dose to areceptor is a function of the concentration atthe exposure point (i.e, the well) and theintake rate by the receptor. The concentrationat the exposure point is based on the releasefrom the source and the fate and transport ofthe constituent. The intake rate is dependenton the exposure route, the frequency of expo-sure, and the duration of exposure.

EPA produced the Exposure FactorsHandbook (U.S. EPA, 1997a) as a reference forproviding a consistent set of exposure factorsto calculate the dose. This reference is avail-able from EPA’s National Center forEnvironmental Assessment Web site<www.epa.gov/ncea>. The purpose of thehandbook is to summarize data on humanbehaviors and physical characteristics (e.g.,body weight) that affect exposure to environ-mental contaminants and recommend valuesto use for these factors. The result of a dosecalculation is expressed as a contaminant con-centration per unit body weight per unit timethat can then be used as the output of theexposure assessment for the risk characteriza-tion phase of the analysis.

3. Toxicity AssessmentA toxicity assessment weighs available evi-

dence regarding the potential for particular

contaminants to cause adverse effects inexposed individuals, and where possible, pro-vides an estimate of the increased likelihoodand severity of adverse effects as a result ofexposure to a contaminant. IWEM uses twodifferent toxicity measures—maximum conta-minant levels (MCLs) and health-based num-bers (HBNs). Each of these measures is basedon toxicity values reflecting a cancer or non-cancer effect. Toxicity data are based onhuman epidemiologic data, animal data, orother supporting studies (e.g., laboratorystudies). In general, data can be used to char-acterize the potential adverse effect of a con-stituent as either carcinogenic ornon-carcinogenic. For the carcinogenic effect,EPA generally assumes there is a non-thresh-old effect and estimates a risk per unit dose.For the noncarcinogenic effect, EPA generallyassumes there is a threshold below which noadverse effects occur. The toxicity values usedin IWEM include:

• Oral cancer slope factors (CSFo) fororal exposure to carcinogenic conta-minants.

• Reference doses (RfD) for oral expo-sure to contaminants that cause non-cancer health effects.

• Inhalation cancer slope factors (CSFi)derived from Unit Risk Factors(URFs) for inhalation exposure to car-cinogenic contaminants.

• Reference concentrations (RfC) forinhalation exposure to contaminantsthat cause noncancer health effects.

EPA defines the cancer slope factor (CSF)as, “an upper bound, approximating a 95 per-cent confidence limit, on the increased cancerrisk from a lifetime exposure to an agent [con-taminant].” Because the CSF is an upperbound estimate of increased risk, EPA is rea-sonably confident that the “true risk” will notexceed the risk estimate derived using the CSFand that the “true risk” is likely to be less than


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predicted. CSFs are expressed in units of pro-portion (of a population) affected per mil-ligram/kilogram-day (mg/kg-day). Fornoncancer health effects, the RfD and the RfCare used as health benchmarks for ingestionand inhalation exposures, respectively. RfDsand RfCs are estimates of daily oral exposureor of continuous inhalation exposure, respec-tively, that are likely to be without an appre-ciable risk of adverse effects in the generalpopulation, including sensitive individuals,over a lifetime. The methodology used todevelop RfDs and RfCs is expected to have anuncertainty spanning an order of magnitude.

a. Maximum Contaminant Levels(MCLs)

MCLs are maximum permissible contami-nant concentrations allowed in public drink-ing water and are established under the SafeDrinking Water Act. For each constituent tobe regulated, EPA first sets a MaximumContaminant Level Goal (MCLG) as a levelthat protects against health risks. The MCLfor each contaminant is then set as close toits MCLG as possible. In developing MCLs,EPA considers not only the health effects ofthe constituents, but also additional factors,such as the cost of treatment, available ana-lytical and treatment technologies. Table 3lists the 57 constituents that have MCLs thatare incorporated in IWEM.

b. Health-based Numbers (HBNs).

The parameters that describe a chemical’stoxicity and a receptor’s exposure to the chem-ical are considered in calculation of theHBN(s) of that chemical. HBNs are the maxi-mum contaminant concentrations in groundwater that are not expected to cause adversenoncancer health effects in the general popula-tion (including sensitive subgroups) or thatwill not result in an additional incidence ofcancer in more than approximately one in one

million individuals exposed to the contami-nant. Lower concentrations of the contami-nant are not likely to cause adverse healtheffects. Exceptions might occur, however, inindividuals exposed to multiple contaminantsthat produce the same health effect. Similarly,a higher incidence of cancer among sensitivesubgroups, highly exposed subpopulations, orpopulations exposed to more than one cancer-causing contaminant might be expected. Asnoted previously, the exposure factors used tocalculate HBNs are described in the ExposureFactors Handbook (U.S. EPA, 1997a).

4. Risk CharacterizationRisk characterization is the integration of

the exposure assessment and the toxicityassessment to generate qualitative and quan-titative expressions of risk. For carcinogens,the target risk level used in IWEM to calcu-late the HBNs is 1 x 10-6. A risk of 1 x 10-6

describes an increased chance of one in amillion of a person developing cancer over alifetime, due to chronic exposure to a specificchemical. The target hazard quotient used tocalculate the HBNs for noncarcinogens is 1.A hazard quotient of 1 indicates that the esti-mated dose is equal to the RfD (the levelbelow which no adverse effect is expected).An HQ of 1, therefore, is frequently EPA’sthreshold of concern for noncancer effects.These targets are used to calculate uniqueHBNs for each constituent of concern andeach exposure route of concern (i.e., inges-tion or inhalation).

Usually, doses less than the RfD (HQ = 1)are not likely to be associated with adversehealth effects and, therefore, are less likely tobe of regulatory concern. As the frequency ormagnitude of the exposures exceeding theRfD increase (HQ > 1), the probability ofadverse effects in a human populationincreases. However, it should not be categori-cally concluded that all doses below the RfD

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7A-13

For list of current MCLs, visit: <www.epa.gov/safewater/mcl.html>

* Listed as Total Trihalomethanes (TTHMs), constituents do not have individually listed MCLs

** Arsenic standard will be lowered to 0.01 mg/L by 2006.

*** Value is drinking water “action level” as specified by 40 CFR 141.32(e) (13) and (14).

Organics with an MCL mg/l mg/l

Benzene 0.005 HCH (Lindane) gamma- 0.0002

Benzo[a]pyrene 0.0002 Heptachlor 0.0004

Bis(2-ethylhexyl)phthalate 0.006 Heptachlor epoxide 0.0002

Bromodichloromethane* 0.10 Hexachlorobenzene 0.001

Butyl-4,6-dinitrophenol,2-sec-(Dinoseb) 0.007 Hexachlorocyclopentadiene 0.05

Carbon tetrachloride 0.005 Methoxychlor 0.04

Chlordane 0.002 Methylene chloride (Dichloromethane) 0.005

Chlorobenzene 0.1 Pentachlorophenol 0.001

Chlorodibromomethane* 0.10 Polychlorinated biphenyls (PCBs) 0.0005

Chloroform* 0.10 Styrene 0.1

Dibromo-3-chloropropane 1,2-(DBCP) 0.0002 TCD Dioxin 2,3,7,8- 0.00000003

Dichlorobenzene 1,2- 0.6 Tetrachloroethylene 0.005

Dichlorobenzene 1,4- 0.075 Toluene 1

Dichloroethane 1,2- 0.005 Toxaphene (chlorinated camphenes) 0.003

Dichloroethylene cis-1,2- 0.07 Tribromomethane (Bromoform)* 0.10

Dichloroethylene trans-1,2- 0.1 Trichlorobenzene 1,2,4- 0.07

Dichloroethylene 1,1-(Vinylidene chloride) 0.007 Trichloroethane 1,1,1- 0.2

Dichlorophenoxyacetic acid 2,4- (2,4-D) 0.07 Trichloroethane 1,1,2- 0.005

Dichloropropane 1,2- 0.005 Trichloroethylene (1,1,2- Trichloroethylene) 0.005

Endrin 0.002 2,4,5-TP (Silvex) 0.05

Ethylbenzene 0.7 Vinyl chloride 0.002

Ethylene dibromide (1,2- Dibromoethane) 0.00005 Xylenes 10

Inorganics with an MCL

Antimony 0.006 Copper*** 1.3

Arsenic** 0.05 Fluoride 4.0

Barium 2.0 Lead*** 0.015

Beryllium 0.004 Mercury (inorganic) 0.002

Cadmium 0.005 Selenium 0.05

Chromium 0.1 Thallium 0.002

(total used for Cr III and Cr VI)

Table 3.

List of Constituents in IWEM with Maximum Contaminant Levels (MCLs)

(States can have more stringent standards than federal MCLs.)

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are “acceptable’’ (or will be risk-free) and thatall doses in excess of the RfD are “unaccept-able’’ (or will result in adverse effects). ForIWEM, the output from the risk characteriza-tion helps determine with 90 percent proba-bility (i.e., with a confidence that for 90percent of the realizations) whether or not adesign system is protective (i.e., has a cancerrisk of < 1 x 10-6, non-cancer hazard quotientof < 1.0). IWEM does not address the cumu-lative risk due to simultaneous exposure tomultiple constituents. The results of the riskassessment might encourage the user to con-duct a more site-specific analysis, or consideropportunities for waste minimization or pol-lution prevention.

II. The IWEMGround-WaterRisk Evaluation

This section takes the principles of riskassessment described in Part I and appliesthem to evaluating industrial waste manage-ment unit liner designs. This is accomplishedusing IWEM and a three-tiered ground-watermodeling approach to make recommenda-tions regarding the liner design systems thatshould be considered for a potential unit, if aliner design system is considered necessary.The tiered approach was chosen to providefacility managers, the public, and state regu-lators flexibility in assessing the appropriate-ness of particular WMU designs as the usermoves from a national assessment to anassessment using site-specific parameters.

The three tiers allow for three possibleapproaches. The first approach is a quickscreening tool, a set of lookup tables, whichprovides conservative national criteria. Whilethis approach, labeled Tier 1, does not takeinto account site- (or even state-) specific con-ditions, it does provide a rapid and easy

screening. If the use of Tier 1 provides anagreeable assessment, the conservative natureof the model can be relied upon, and theadditional resources required for furtheranalysis can be avoided. Of course, wherethere is concern with the results from Tier 1,a more precise assessment of risk at theplanned unit location should be conducted.The second approach is to try and accommo-date many of the most important site-specificfactors in a simplified form, useable by indus-try, state, and environmental representatives.This model, labeled Tier 2, is available as partof this Guide, and is a major new step inmoving EPA guidance away from national,“one size fits all” approaches. Third, a site-specific risk analysis can be conducted. Thisapproach should provide the most preciseassessment of the risks posed by the plannedunit. Such an analysis, labeled Tier 3, shouldbe conducted by experts in ground-watermodeling, and can require significantresources. This Guide identifies the benefitsand sources for selecting site-specific models,but does not provide such models as part ofthis Guide. In many cases, corporations willgo directly to conducting the more exactingTier 3 analysis, which EPA believes is accept-able under the Guide. There is, however, stilla need for the Tier 2 tool. State and environ-mental representatives might have limitedresources to conduct or examine a Tier 3assessment; Tier 2 can provide a point ofcomparison with the results of the Tier 3analysis, narrow the technical discussion tothose factors which are different in the mod-els, and form a basis for a more informed dia-logue on the reasonableness of the differences.

IWEM is designed to address Tier 1 andTier 2 evaluations. Both tiers of the tool con-sider all portions of the risk assessmentprocess (i.e., problem formulation, exposureassessment, toxicity assessment, and riskcharacterization) to generate results that varyfrom a national-level screening evaluation to

a site-specific assessment. The Tier 3 evalua-tion is a complex, site-specific hydrogeologicinvestigation that would be performed withother models such as those listed at the endof this chapter. Those models could be usedto evaluate hydrogeological complexities thatare not addressed by IWEM. Brief outlines ofthe three tiers follow.

A Tier 1 evaluation involves comparing theexpected leachate concentrations of wastesbeing assessed against a set of pre-calculatedmaximum recommended leachate concentra-tions (or Leachate Concentration ThresholdValues—LCTVs). The Tier 1 LCTVs arenationwide, ground-water fate and transportmodeling results from EPA’s Composite Modelfor Leachate Migration with TransformationProducts (EPACMTP). EPACMTP simulatesthe fate and transport of leachate infiltratingfrom the bottom of a WMU and predicts con-centrations of those contaminants in a well. Inmaking these predictions, the model quantita-tively accounts for many complex processesthat dilute and attenuate the concentrations ofwaste constituents as they move through thesubsurface to the well. The results that aregenerated show whether a liner system is con-sidered necessary, and if so which liner sys-tems will be protective for the constituents ofconcern. Tier 1 results are designed to be pro-tective with 90 percent certainty at a 1x10-6

risk level for carcinogens or a noncancer haz-ard quotient of < 1.0.

The Tier 2 evaluation incorporates a limit-ed number of site-specific parameters to helpprovide recommendations about which linersystem (if any is considered necessary) is pro-tective for constituents of concern in settingsthat are more reflective of your site. IWEM isdesigned to facilitate site-specific simulationswithout requiring the user to have any previ-ous ground-water modeling experience. Aswith any ground-water risk evaluation, how-ever, the user is advised to discuss the results

of the Tier 2 evaluation with the appropriatestate regulatory agency before selecting a linerdesign for a new WMU.

If the Tier 1 and Tier 2 modeling do notadequately simulate conditions at a proposedsite because the hydrogeology of the site iscomplex, or because the user believes Tier 2does not adequately address a particular site-specific parameter, the user is advised to con-sider a more in-depth, site-specific riskassessment. This Tier 3 assessment involves amore detailed, site-specific ground-water fateand transport analysis. The user should con-sult with state officials and appropriate tradeassociations to solicit recommendations forapproaches for the analysis.

The remainder of this section discusses ingreater detail how to use IWEM to perform aTier 1 or Tier 2 evaluation. In addition, thissection presents information concerning theuse of Tier 3 models.

A. The Industrial WasteManagement EvaluationModel (IWEM)

The IWEM is the ground-water modelingcomponent of the Guide for Industrial WasteManagement, used for recommending appro-priate liner system designs, where they areconsidered necessary, for the management ofRCRA Subtitle D industrial waste. IWEMcompares the expected leachate concentration(entered by the user) for each waste con-stituent with a protective level calculated by aground-water fate and transport model todetermine whether a liner system is needed.When IWEM determines a liner system isnecessary, it then evaluates two standard linertypes (i.e., single clay-liner and compositeliner). This section discusses components ofthe tool and important concepts whose under-standing is necessary for its effective use. Theuser can refer to the User’s Guide for the


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Industrial Waste Management Evaluation Model(U.S. EPA, 2002b) for information necessaryto perform Tier 1 and Tier 2 analyses, and theIndustrial Waste Management Evaluation ModelTechnical Background Document (U.S. EPA,2002a), for more information on the use anddevelopment of IWEM.

1. Leachate ConcentrationsThe first step in determining a protective

waste management unit design is to identifythe expected constituents in the waste andexpected leachate concentrations from thewaste. In order to assess ground-water risksusing either the Tier 1 or Tier 2 evaluationsprovided in IWEM, the expected leachateconcentration for each individual constituentof interest must be entered into the model.See Chapter 2—Characterizing Wastes, for adetailed discussion of the various approachesavailable to use in evaluating expectedleachate concentrations.

2. Models Associated with IWEMOne of the highlights of IWEM is its abili-

ty to simulate the fate and transport of wasteconstituents at a WMU with a small numberof site-specific inputs. To accomplish thistask, IWEM incorporates the outputs of threeother models, specifically EPACMTP, MINTE-QA2, and HELP. This section discusses thesethree models.

a. EPACMTP

EPA’s Composite Model for LeachateMigration with Transformation Products(EPACMTP) is the backbone of IWEM.EPACMTP is designed to simulate subsurfacefate and transport of contaminants leachingfrom the bottom of a WMU and predict con-centrations of those contaminants in a down-gradient well. In making these predictions,the model accounts for many complex

processes that occur as waste constituentsand their transformation products move toand through ground water. As leachate carry-ing waste constituents migrates through theunsaturated zone to the water table, attenua-tion processes, such as adsorption and degra-dation, reduce constituent concentrations.Ground-water transport in the saturated zonefurther reduces leachate concentrationsthrough dilution and attenuation. The con-centration of constituents arriving at a well,therefore, is lower than that in the leachatereleased from a WMU.

In the unsaturated zone, the model simu-lates one-dimensional vertical migration withsteady infiltration of constituents from theWMU. In the saturated zone, EPACMTP sim-ulates three-dimensional plume-movement(i.e., horizontal as well as transverse and ver-tical spreading of a contaminant plume). Themodel considers not only the subsurface fateand transport of constituents, but also theformation and the fate and transport of trans-formation (daughter and granddaughter)products. The model also can simulate thefate and transport of metals, taking intoaccount geochemical influences on themobility of metals.

b. MINTEQA2

In the subsurface, metal contaminants canundergo reactions with other substances inthe ground water and with the solid aquiferor soil matrix material. Reactions in whichthe metal is bound to the solid matrix arereferred to as sorption reactions, and themetal bound to the solid is said to be sorbed.During contaminant transport, sorption tothe solid matrix results in retardation (slowermovement) of the contaminant front.Transport models such as EPACMTP incorpo-rate a retardation factor to account for sorp-tion processes.

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The actual geochemical processes that con-trol the sorption of metals can be quite com-plex, and are influenced by factors such aspH, the type and concentration of the metalin the leachate plume, the presence and con-centrations of other constituents in theleachate plume, and other factors. TheEPACMTP model is not capable of simulatingall these processes in detail. Another model,MINTEQA25, is used to determine a sorptioncoefficient for each of the metals species. ForIWEM, distributions of variables (e.g., leach-able organic matter, pH) were used to gener-ate a distribution of isotherms for each metalspecies. EPACMTP, in turn, samples fromthese calculated sorption coefficients and usesthe selected isotherm as a modeling input toaccount for the effects of nationwide oraquifer-specific ground-water and leachategeochemistry on the sorption and mobility ofmetals constituents.

c. HELP

The Hydrologic Evaluation of LandfillPerformance (HELP) model is a quasi-two-dimensional hydrologic model for computingwater balances of landfills, cover systems, andother solid waste management facilities. Theprimary purpose of the model is to assist inthe comparison of design alternatives. HELPuses weather, soil, and design data to com-pute a water balance for landfill systemsaccounting for the effects of surface storage;snowmelt; runoff; infiltration; evapotranspira-tion; vegetative growth; soil moisture storage;lateral subsurface drainage; leachate recircula-tion; unsaturated vertical drainage; and leak-age through soil, geomembrane, or compositeliners. The HELP model can simulate landfillsystems consisting of various combinations ofvegetation, cover soils, waste cells, lateraldrain layers, low permeability barrier soils,and synthetic geomembrane liners. For fur-ther information on the HELP model, visit:<wes.army.mil/el/elmodels/helpinfo.html>.

For the application of HELP to IWEM, anexisting database of infiltration and rechargerates was used for 97 climate stations in thelower 48 contiguous states. Five climate sta-tions (located in Alaska, Hawaii, and PuertoRico) were added to ensure coveragethroughout all of the United States. These cli-matic data were then used along with data onthe soil type and WMU design characteristics,to calculate a water balance for each applica-ble liner design as a function of the amountof precipitation that reaches the surface of theunit, minus the amount of runoff and evapo-transpiration. The HELP model then comput-ed the net amount of water that infiltratesthrough the surface of the unit (accountingfor recharge), the waste, and the unit’s bottomlayer (for unsaturated soil and clay liner sce-narios only), based on the initial moisturecontent and the hydraulic conductivity ofeach layer.

Although data were collected for all 102sites, these data were only used for theunlined landfills, waste piles, and land appli-cation units. For the clay liner scenarios(landfills and waste piles only), EPA groupedsites and ran the HELP model only for a sub-set of the facilities that were representative ofthe ranges of precipitation, evaporation, andsoil type. The grouping is discussed further inthe IWEM Technical Background Document(U.S. EPA, 2002a).

In addition to climate factors and the par-ticular unit design, the infiltration rates calcu-lated by HELP are affected by the landfillcover design, the permeability of the wastematerial in waste piles, and the soil type ofthe land application unit. For every climatestation and WMU design, multiple HELPinfiltration rates are calculated. In Tier 1, fora selected WMU type and design, theEPACMTP Monte Carlo modeling processwas used to randomly select from among theHELP-derived infiltration and recharge data.


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5 MINTEQA2 is a geochemical equilibrium speciation model for computing equilibria among the dis-solved, absorbed, solid, and gas phases in dilute aqueous solution.

This process captured both the nationwidevariation in climate conditions and variationsin soil type. In Tier 2, the WMU location is arequired user input, and the climate factorsused in HELP are fixed. However, in Tier 2,the Monte Carlo process is still used toaccount for local variability in the soil type,landfill cover design, and permeability ofwaste placed in waste piles.

3. Important Concepts for Useof IWEM

Several important concepts are critical tounderstanding how IWEM functions. Theseconcepts include 90th percentile exposureconcentration, dilution and attenuations fac-tors (DAFs), reference ground-water concen-trations (RGCs), leachate concentrationthreshold values (LCTVs), and units designs.

a. 90th Percentile ExposureConcentration

The 90th percentile exposure concentra-tion was chosen to represent the estimatedconstituent concentration at a well for agiven leachate concentration. The 90th per-centile exposure concentration was selectedbecause this concentration is protective for90 percent of the model simulations con-ducted for a Tier 1 or Tier 2 analysis. In Tier1, the 90th percentile concentration is usedto calculate a DAF, which is then used to gen-erate a leachate concentration threshold value(LCTV). In Tier 2, the 90th percentile con-centration is directly compared with a refer-ence ground-water concentration todetermine whether a liner system is neces-sary, and if so whether the particular linerdesign is protective for a site.

The 90th percentile exposure concentra-tion is determined by running EPACMTP in aMonte Carlo mode for 10,000 realizations.For each realization, EPACMTP calculates amaximum average concentration at a well,

depending on the exposure duration of thereference ground-water concentration (RGC)of interest. For example, IWEM assumes a30-year exposure duration for carcinogens,and therefore, the maximum average concen-tration is the highest 30-year average acrossthe modeling horizon. After calculating themaximum average concentrations across the10,000 realizations, the concentrations arearrayed from lowest to highest and the 90thpercentile of this distribution is selected asthe constituent concentration for IWEM.

Once the 90th percentile exposure con-centration is determined, it is used in one oftwo ways. For both the Tier 1 analysis andthe Tier 2 analysis, the 90th percentile expo-sure concentration is compared with theexpected waste leachate concentration togenerate a DAF. This calculation is discussedfurther in the following section. For Tier 2,the 90th percentile exposure concentration isthe concentration of interest for the analysis.The 90th percentile exposure concentrationcan be directly compared with the referenceground-water concentration to assist in wastemanagement decision-making.

b. Dilution and Attenuation Factors

DAFs represent the expected reduction inwaste constituent concentration resultingfrom fate and transport in the subsurface. ADAF is defined as the ratio of the constituentconcentration in the waste leachate to theconcentration at the well, or:

CL

DAF = ———

CW

where: DAF is the dilution and attenua-tion factor;

CL is the leachate concentration(mg/L); and

CW is the ground-water well con-centration (mg/L).

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The magnitude of a DAF reflects the com-bined effect of all dilution and attenuationprocesses that occur in the unsaturated andsaturated zones. The lowest possible value ofa DAF is one. A DAF of 1 means that there isno dilution or attenuation at all; the concen-tration at a well is the same as that in thewaste leachate. High DAF values, on theother hand, correspond to a high degree ofdilution and attenuation. This means that theexpected concentration at the well will bemuch lower than the concentration in theleachate. For any specific site, the DAFdepends on the interaction of waste con-stituent characteristics (e.g., whether or notthe constituent degrades or sorbs), site-specif-ic factors (e.g., depth to ground water, hydro-geology), and physical and chemicalprocesses in the subsurface environment. Inaddition, the DAF calculation does not takeinto account when the exposure occurs, aslong as it is within a 10,000-year time-framefollowing the initial release of leachate. Thus,if two constituents have different mobility, thefirst might reach the well in 10 years, whilethe second constituent might not reach thewell for several hundred years. EPACMTP,however, can calculate the same or very simi-lar DAF values for both constituents.

For the Tier 1 analysis in IWEM, DAFs arebased on the 90th percentile exposure con-centration. EPACMTP was implemented byrandomly selecting one of the settings fromthe WMU database and assigning a unitleachate concentration to each site until10,000 runs had been conducted for a WMU.The resulting 10,000 maximum well concen-trations based on the averaging period associ-ated with the exposure duration of interest(i.e., 1-year, 7-years, 30-years) were thenarrayed from lowest to highest. The 90th per-centile concentration of this distribution isthen used as the concentration in the ground-water well (Cw) for calculating the DAF. TheDAF is similarly calculated for the Tier 2, but

because the site-specific leachate concentra-tion is used in the EPACMTP model runs, the90th percentile exposure concentration canbe compared directly to the RGC.

c. Reference Ground-WaterConcentration (RGC)

As used in this Guide and by IWEM, a ref-erence ground-water concentration (RGC) isdefined as a constituent concentration thresh-old in a well that is protective of humanhealth. RGCs have been developed based onmaximum contaminant levels (MCLs) andhealth-based-numbers (HBN). Each con-stituent can have up to five RGCs: 1) basedon an MCL, 2) based on carcinogenic effectsfrom ingestion, 3) based on carcinogeniceffects from inhalation while showering, 4)based on non-carcinogenic effects from inges-tion, and 5) based on non-carcinogeniceffects from inhalation while showering.

The IWEM’s database includes 226 con-stituents with at least one RGC. Of the 226constituents, 57 have MCLs (see Table 3),212 have ground-water ingestion HBNs, 139have inhalation HBNs, and 57 have both anMCL and HBN. The HBNs were developedusing standard EPA exposure assumptions forresidential receptors. For carcinogens, IWEMused a target risk level equal to the probabili-ty that there might be one increased cancercase per one million exposed people (com-monly referred to as a 1x10-6 cancer risk).The target hazard quotient used to calculatethe HBNs for noncarcinogens was 1 (unit-less). A hazard quotient of 1 indicates thatthe estimated dose is equal to the oral refer-ence dose (RfD) or inhalation reference con-centration (RfC). These targets were used tocalculate unique HBNs for each constituent ofconcern and each exposure route of concern(ingestion or inhalation). For further informa-tion on the derivation of the IWEM RGCs,see the Industrial Waste ManagementEvaluation Model Technical Background


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Document (U.S. EPA, 2002a). Users also canadd new constituents and RGCs can varydepending on the protective goal. For exam-ple, states can impose more stringent drink-ing water standards than federal MCLs.6 Tokeep the software developed for this Guideup-to-date, and to accommodate concerns atlevels different from the current RGCs, theRGC values in the IWEM software tool canbe modified by the user of the software.

d. Leachate Concentration ThresholdValues (LCTVs)

The purpose of the Tier 1 analysis inIWEM is to determine whether a liner systemis needed, and if so, to recommend liner sys-tem designs or determine the appropriatenessof land application with minimal site-specificdata. These recommendations are based onLCTVs that were calculated to be protectivefor each waste constituent in a unit. TheseLCTVs are the maximum leachate concentra-tions for which water in a well is not likely toexceed the corresponding RGC. The LCTVfor each constituent accounts for dilution andattenuation in the unsaturated and saturatedzones prior to reaching a well. An LCTV hasbeen generated for a no liner/in situ soils sce-nario and for two standard liner types (i.e.,single clay liner and composite liner) andeach RGC developed for a constituent.

The LCTV for a specific constituent is theproduct of the RGC and the DAF:

LCTV = DAF * MCL

or LCTV = DAF * HBN

Where: LCTV is the leachate concentra-tion threshold value

DAF is the dilution and attenua-tion factor

MCL is the maximum concentra-tion level

HBN is the health-based number

The evaluation of whether a liner system isneeded and subsequent liner system designrecommendations is determined by compar-ing the expected waste constituent leachateconcentrations to the corresponding calculat-ed LCTVs. LCTVs are calculated for all unittypes (i.e., landfills, waste piles, surfaceimpoundments, land application units) bytype of design (i.e., no liner/in situ soils, sin-gle liner, or composite liner).7 The Tier 1evaluation is generally the most protectiveand calculates LCTVs using data collected onWMUs throughout the United States.8 LCTVsused in Tier 1 are designed to be protectiveto a level of 1x10-6 for carcinogens or a non-cancer hazard quotient of < 1.0 with a 90percent certainty considering the range ofvariability associated with the waste sitesacross the United States. LCTVs from the Tier1 analysis are generally applicable to sitesacross the country; users can determinewhether a specific liner design for a WMU isprotective by comparing expected leachateconcentrations for constituents in their wastewith the LCTVs for each liner design.

The Tier 2 analysis differs from the Tier 1analysis in that IWEM calculates a site-specif-ic DAF in Tier 2. This allows the model tocalculate a site-specific 90th percentile expo-sure concentration that can be comparedwith an RGC to determine if a liner system isneeded and to recommend the appropriateliner system if necessary. The additional cal-culation of an LCTV is not necessary. IWEMcontinues to perform the calculation, howev-er, to help users determine whether wasteminimization might be appropriate to meet aspecific design. For example, a facility might

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6 For example, a state can make secondary MCLs mandatory, which are not federally enforceable stan-dards, or a state might use different exposure assumptions, which can result in a different HBN. Inaddition, states can choose to use a different risk target than is used in this Guidance.

7 LCTVs are influenced by liner designs because of different infiltration rates.

8 For additional information on the nationwide data used in the modeling, see the IWEM TechnicalBackground Document (U.S. EPA, 2002a).


find it more cost effective to reduce the con-centration of constituents in its waste anddesign a clay-lined landfill than to dispose ofthe current waste in a composite landfill. TheLCTV calculated for the Tier 2 analysis isbased on the expected leachate concentrationfor a specific site and site-specific data forseveral sensitive parameters. Because the Tier2 analysis includes site-specific considera-tions, LCTVs from this analysis are notapplicable to other sites.

e. Determination of Liner Designs

The primary method of controlling therelease of waste constituents to the subsurfaceis to install a low permeability liner at thebase of a WMU. A liner generally consists of alayer of clay or other material with a lowhydraulic conductivity that is used to preventor mitigate the flow of liquids from a WMU.The type of liner that is appropriate for a spe-cific WMU, however, is highly dependentupon a number of location-specific character-istics, such as climate and hydrogeology.These characteristics are critical in determin-ing the amount of liquid that migrates intothe subsurface from a WMU and in predictingthe release of contaminants to ground water.

The IWEM software is intended to assistthe user in determining if a new industrialwaste management unit can rely on a noliner/in situ soils design, or whether one ofthe two recommended liners designs, singleclay liner or composite liner, should be used.The no liner/in situ soils design (Figure 2a)represents a WMU that relies upon location-specific conditions, such as low permeabilitynative soils beneath the unit or low annualprecipitation rates to mitigate the release ofcontaminants to groundwater. The single clayliner (Figure 2b) design represents a 3-footthick clay liner with a low hydraulic conduc-tivity (1x10-7 cm/sec) beneath a WMU. Acomposite liner design (Figure 2c) consists of

a flexible membrane liner in contact with aclay liner. In Tier 2, users also can evaluateother liner designs by providing a site-specificinfiltration rate based on the liner design. Forland applications units, only the no liner/insitu soils scenario is evaluated because linersare not typically used at this type of facility.

To determine an appropriate design in Tier1, IWEM compares expected leachate con-centrations for all of the constituents in theleachate to constituent-specific LCTVs andthen reports the minimum design system thatis protective for all constituents. If the expect-ed leachate concentrations of all waste con-stituents are lower than their respective noliner/in situ soils LCTVs, the proposed WMUdoes not need a liner to contain the waste.On the other hand, if the Tier 1 screeningevaluation indicates a liner is recommended,a user can verify this recommendation with afollow-up Tier 2 (or possibly Tier 3) analysisfor at least those constituents whose expectedleachate concentrations exceed the Tier 1LCTV values.

If the user proceeds to a Tier 2 analysis,IWEM will evaluate the three standarddesigns or it can evaluate a user-suppliedliner design. The user can supply a linerdesign by providing a site-specific infiltrationrate that reflects the expected infiltration ratethrough the user’s liner system. In the Tier 2analysis, IWEM conducts a location-adjustedMonte Carlo analysis based on user inputs togenerate a 90th percentile exposure concen-tration for the site. The 90th percentile expo-sure concentration is then compared with theRGC to determine whether a liner is consid-ered necessary, and where appropriate, rec-ommend the design that is protective for eachconstituent expected in the leachate. If theTier 2 analysis indicates that the no liner/insitu soils scenario or the user-defined liner isnot protective, the user can proceed to a fullsite-specific Tier 3 analysis.


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B. Tier 1 EvaluationsIn a Tier 1 evaluation, IWEM compares

the expected leachate concentration for eachconstituent with the LCTVs calculated forthese constituents and determines a mini-mum recommended design that is protectivefor all waste constituents. The requiredinputs are: the type of WMU the user wishesto evaluate, the constituents of concern, andthe expected leachate concentrations of con-stituents of concern. The results for eachconstituent have been compiled for each unittype and design and are available in theIWEM Technical Background Document (U.S.EPA, 2002a) and in the model on the CD-ROM version of this Guide.

The tabulated results for Tier 1 of IWEMhave been generated by running theEPACMTP for a wide range of conditions thatreflect the varying site conditions that can beexpected to occur at waste sites across theUnited States. The process, which was usedto simulate varying site conditions, is knownas a Monte Carlo analysis. A Monte Carloanalysis determines the statistical probabilityor certainty that the release of leachate mightresult in a ground-water concentrationexceeding regulatory or risk-based standards.

For the Tier 1 analysis, 10,000 realizationsof EPACMTP were run for each constituent,WMU, and design combination to generatedistributions of maximum average exposure

concentrations for each constituent by WMUand design. These distributions reflect the vari-ability among industrial waste managementunits across the United States. The 90th per-centile concentration from this distribution wasthen used to calculate a DAF for each con-stituent by WMU and design. Each of theseDAFs was then combined with constituent-specific RGCs to generate the LCTVs presented

Figure 2. Three Liner Scenarios Considered in the Tiered Modeling Approach for Industrial

Waste Guidelines

��yyyyyy

Waste

Native Soil

Waste

Clay Liner

Waste

Clay Liner

FlexibleMembraneLiner

a) No Liner/In Situ Soils Scenario b) Single Liner Scenario c) Composite Liner Scenario

About Monte Carlo AnalysisMonte Carlo analysis is a computer-

based method of analysis developed inthe 1940s that uses statistical samplingtechniques in obtaining a probabilisticapproximation to the solution of a math-ematical equation or model. The namerefers to the city on the French Riviera,which is known for its gambling andother games of chance. Monte Carloanalysis is increasingly used in riskassessments because it allows the riskmanager to make decisions based on astatistical level of protection that reflectsthe variability and/or uncertainty in riskparameters or processes, rather thanmaking decisions based on a single pointestimate of risk. For further informationon Monte Carlo analysis in risk assess-ment, see EPA’s Guiding Principles forMonte Carlo Analysis. (U.S. EPA, 1997b).

in the IWEM software and in the tables includ-ed in the technical background document.

The advantages of a Tier 1 screening evalu-ation are that it is fast, and it does not requiresite-specific information. The disadvantage ofthe Tier 1 screening evaluation is that theanalysis does not use site-specific informationand might result in a design recommendationthat is more stringent than is needed for aparticular site. For instance, site-specific con-ditions, such as low precipitation and a deepunsaturated zone, might warrant a less strin-gent design. Before implementing a Tier 1recommendation, it is recommended that youalso perform a Tier 2 assessment for at leastthose waste constituents for which Tier 1indicates that a no liner design is not protec-tive. The following sections provide addition-al information on how to use the Tier 1lookup tables.

1. How Are the Tier 1 LookupTables Used?

The Tier 1 tables provide an easy-to-usetool to assist waste management decision-making. Important benefits of the Tier 1approach are that it requires minimum datafrom the user and provides immediate guid-ance on protective design scenarios. There areonly three data requirements for the Tier 1analysis: WMU type, constituents expected inthe waste leachate, and the expected leachateconcentration for each constituent in thewaste. The Tier 1 tables are able to provideimmediate guidance because EPACMTP simu-lations for each constituent, WMU, anddesign combinations were run previously fora national-scale assessment to generate appro-priate LCTVs for each combination. Becausethe simulations represent a national-scaleassessment, the LCTVs in the Tier 1 tablesrepresent levels in leachate that are protectiveat most sites.

As noted previously in this chapter, one ofthe first steps in a ground-water risk assess-ment is to characterize the waste going into aunit. Characterization of the waste includesidentifying the constituents expected in theleachate and estimating leachate concentra-tions for each of these constituents.Identification of constituents expected inleachate can be based on process knowledgeor chemical analysis of the waste. Leachateconcentrations can be estimated usingprocess knowledge or an analytical leachingtest appropriate to the circumstances, such asthe Toxicity Characteristic LeachingProcedure (TCLP). For more information onidentifying waste constituents, estimatingwaste constituent leachate concentrations,and selecting appropriate leaching tests, referto Chapter 2 — Characterizing Waste.

The following example illustrates the Tier1 process for evaluating a proposed designfor an industrial landfill. The exampleassumes the expected leachate concentrationfor toluene is 1.6 mg/L and styrene is 1.0


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Information Needed toUse Tier 1 Lookup TablesWaste management Landfill, surfaceunit types: impoundment,

waste pile, or landapplication unit.

Constituents Constituent namesexpected and/or CAS numbers.in the leachate:

Leachate Expected leachateconcentrations: concentration of

each constituent orconcentration insurface impound-ments or waste to beapplied.

mg/L. Both toluene and styrene have threeLCTVs: one based on an MCL, one based onnon-cancer ingestion, and one based on non-cancer inhalation. Tables 4 and 5 providedetailed summary information for the noliner/in situ soils scenario for MCL-basedLCTVs and the HBN-based LCTVs, respec-tively, that is similar to the information thatcan be found in the actual look-up tables.

For the Tier 1 MCL-based analysis pre-sented in Table 4, the results provide thefollowing information: constituent CASnumber, constituent name, constituent-spe-cific MCL, user-provided leachate concen-tration, constituent-specific DAF, theconstituent-specific LCTV, and whether thespecified design is protective at the targetrisk level. To provide a recommendation asto whether a specific design is protective ornot, IWEM compares the LCTV with theleachate concentration to determinewhether the design is protective. In theexample presented in Table 4, the noliner/in situ soils scenario is not protectivefor styrene because the leachate concentra-tion provided by the user (1.0 mg/L) isgreater than the Tier 1 LCTV (0.22 mg/L).For toluene, the no liner/in situ soils sce-nario is protective because the leachate con-centration (1.6 mg/L) is less than the Tier 1LCTV (2.2 mg/L).

For the health-based number (HBN)-basedresults presented in Table 5, the detailedresults present similar information to thatpresented for the MCL-based results. The dif-

ferences are that the HBN-results present theconstituent-specific HBN rather than theMCL and include an additional column thatidentifies the pathway and effect that supportthe development of the LCTV. For the con-trolling pathway and effect column, IWEMwould indicate whether the most protectivepathway is ingestion of drinking water (indi-cated by ingestion) or inhalation duringshowering (indicated by inhalation) andwhether the adverse effect is a cancer or non-cancer effect. In this example, both styreneand toluene have two HBN-based LCTVS:one for ingestion non-cancer and one forinhalation non-cancer. Only the results forthe controlling HBN exposure pathway andeffect are shown. In Table 5, only the resultsfor the inhalation-during-showering pathwayfor non-cancer effects are shown because thisis the most protective pathway (that is, theLCTV for the inhalation-during-showingpathway is lower than the LCTV for ingestionof drinking water) for both of these con-stituents. As shown in Table 5, comparison ofthe leachate concentration of styrene (1.0mg/L) and toluene (1.6 mg/L) to their respec-tive LCTVs (8.0 mg/L and 2.9 mg/L) indi-cates that the no liner/in situ soils design isprotective for the Tier 1 HBN-based LCTVs.

Based on the results for the no liner/in situsoils scenario, the user could proceed to thecomparison of the expected leachate concen-tration for styrene with the MCL-based LCTVfor a single clay liner to determine whetherthe single clay liner design is protective. The

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CAS # Constituent MCL (mg/L) Leachate Concentration (mg/L) DAF LCTV (mg/L) Protective?

100-42-5 Styrene 0.1 1.0 2.2 0.22 No

108-88-3 Toluene 1.0 1.6 2.2 2.2 Yes

Table 4:

Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - No Liner/In situ Soils

user also can proceed to a Tier 2 or Tier 3analysis to determine whether a more site-specific approach might indicate that the noliner/in situ soils design is protective for thesite. Table 6 presents the Tier 1 results for thesingle clay liner. As shown, the single clayliner would not be protective for the MCL-based analysis because the expected leachateconcentration for styrene (1.0 mg/L) exceedsthe LCTV for styrene (0.61 mg/L). Based onthese results, the user could continue on toevaluate whether a composite liner is protec-tive for styrene.

Table 7 presents the results of the Tier 1MCL-based analysis for a composite liner.9 Acomparison of the leachate concentration forstyrene (1.0 mg/L) to the MCL-based LCTV(1000 mg/L) indicates that the compositeliner is the recommended liner based on aTier 1 analysis that will be protective for bothstyrene and toluene.

2. What Do the Results Meanand How Do I Interpret Them?

For the Tier 1 analysis, IWEM evaluatesthe no liner/in situ soils, single clay liner, and


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9 Table 7 also indicates the effect of the 1000 mg/L cap on the results. The LCTV results from multiply-ing the RGC with the DAF. In this example, the MCL for styrene (0.1 mg/L) multiplied by the unitlessDAF (5.4 x 104) would result in an LCTV of 5,400 mg/L, but because LCTVs are capped, the LCTV forstyrene in a composite liner is capped at 1,000 mg/L. See Chapter 6 of the Industrial Waste ManagementEvaluation Model Technical Background Document (U.S. EPA, 2002a) for further information.

CAS # Constituent HBN (mg/L) Leachate DAF LCTV (mg/L) Protective? Controlling Concentration Pathway &

(mg/L) Effect

100-42-5 Styrene 3.6 1.0 2.2 8.0 Yes Inhalation Non-cancer

108-88-3 Toluene 1.3 1.6 2.2 2.9 Yes Inhalation Non-cancer

Table 5:

Example of Tier 1 Summary Table for HBN-based LCTVs for Landfills - No Liner/In situ Soils


100-42-5 Styrene 0.1 1.0 5.4x104 1000 Yes

108-88-3 Toluene 1.0 1.6 2.9x104 1000 Yes

Table 7:

Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - Composite Liner


100-42-5 Styrene 0.1 1.0 6.1 0.61 No

108-88-3 Toluene 1.0 1.6 6.1 6.1 Yes

Table 6:

Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - Single Clay Liner

composite liner design scenarios, in thatorder. Generally, if the expected leachate con-centrations for all constituents are lower thanthe no liner LCTVs, the proposed unit doesnot need a liner to contain this waste. If anyexpected constituent concentration is higherthan the no liner/in situ soils LCTV, a singlecompacted clay liner or composite linerwould be recommended for containment ofthe waste using the Tier 1 analysis. If anyexpected concentration is higher than thesingle clay liner LCTV, the recommendationis at least a composite liner. If any expectedconcentration is higher than the compositeliner LCTV, pollution prevention, treatment,or additional controls should be considered,or a Tier 2 or Tier 3 analysis can be conduct-ed to consider site-specific factors beforemaking a final judgment. For waste streamswith multiple constituents, the most protec-tive design that is recommended for any oneconstituent is the overall recommendation. Inthe example illustrated in Tables 4, 5, 6, and7, the recommended design is a compositeliner because the expected leachate concen-tration for styrene exceeds the no liner/in situsoils and clay liner LCTVs in the MCL-basedanalysis, but is lower than the compositeliner LCTV. For the HBN-based analysis, a noliner/in situ soils design would provide ade-quate protection for the site because, asshown in Table 5, the leachate concentrationsfor styrene and toluene are lower than theirrespective HBN-based LCTVs.

The interpretation for land application issimilar to the interpretation for landfills.However, only the no liner/in situ soils sce-nario is evaluated for land applicationbecause these types of units generally do notuse liner systems. Thus, if all the wasteleachate concentrations are below the noliner/in situ soils MCL-based and HBN-basedLCTVs in the Tier 1 lookup tables, land-applying waste might be appropriate for thesite. If the waste has one or more con-

stituents whose concentrations exceed a landapplication threshold, the recommendation isthat land application might not be appropri-ate. The model does not consider the otherdesign scenarios.

After conducting the Tier 1 evaluation,users should consider the following steps:

• Perform additional evaluations.The Tier 1 evaluation provides a con-servative screening assessment whosevalues are calculated to be protectiveover a range of conditions and situa-tions. Although a user could elect toinstall a liner based on the Tier 1results, it is appropriate that a userconsider Tier 2 or Tier 3 evaluationsto confirm these recommendations.

• Consider pollution prevention,recycling, or treatment. If you donot want to conduct a Tier 2 or Tier3 analysis, and the waste has one ormore “problem” constituents that callfor a more stringent and costly designsystem (or which make land applica-tion inappropriate), you could con-sider pollution prevention, recycling,and treatment options for those con-stituents. Options that previouslymight have appeared economicallyinfeasible, might be worthwhile ifthey can reduce the problem con-stituent concentration to a level thatresults in a different design recom-mendation or would make landapplication appropriate. Then, afterimplementing these measures, repeatthe Tier 1 evaluation. Based on theresults presented in Table 6, pollutionprevention, recycling, or treatmentmeasures could be used to reduce theexpected leachate concentration forstyrene below 0.61 mg/L so that asingle liner is recommended for theunit. Consult Chapter 3—Integrating

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Pollution Prevention, for ideas andtools.

• Implement recommendations. Youcan design the unit based on thedesign recommendations of the Tier1 lookup tables without performingfurther analysis or considering pollu-tion prevention or recycling activities.In the case of land application, a landapplication system might be devel-oped (after evaluating other factors) ifthe lookup tables found no liner nec-essary for all constituents. In eithercase, it is recommended that youconsult the appropri-ate agency to ensurecompliance withstate regulations.

Figure 3 illustrates thebasic steps using the Tier 1lookup tables to determinean appropriate design for aproposed waste manage-ment unit or whether landapplication is appropriate.

C. Tier 2Evaluations

The Tier 2 evaluation isdesigned to provide amore accurate evaluationthan Tier 1 by allowingthe user to provide site-specific data. In manycases, a Tier 2 evaluationmight suggest a less strin-gent and less costly designthan a Tier 1 evaluationwould recommend. Thissection describes theinputs for the analysis andthe process for determin-ing a protective recom-mendation.

1. How is a Tier 2 AnalysisPerformed?

Under Tier 2, the user can provide site-specific information to refine the design rec-ommendations. The Tier 2 analysis leads theuser through a series of data entry screensand then runs EPACMTP to generate a designrecommendation based on the site-specificinformation provided by the user. The usercan provide data related to the WMU, thesubsurface environment, infiltration rates,physicochemical properties, and toxicity. Theuser can evaluate the three designs discussedabove or provide data reflecting a site-specific


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Consider implement-ing liner and/or landapplication recom-

mendation, or obtain-ing additional data for

a Tier 2 or Tier 3analysis.

Consider a Tier 2 evaluation orperforming a comprehensive Tier3 site-specific ground-water fate

and transport analysis.

Identify proposed WMU type.

Will pollution preven-tion, recycling, or treat-ment be implemented toreduce concentrations of

problem constituents?

Do you have site-specific

data?

YES

NO

YES

Estimate waste leachate concentration forall potential constituents expected to be

present in the waste.

Compare expected leachate concentrationsto calculated LCTVs for all potential

constituents.

Figure 3. Using Tier 1 Lookup Tables

NO

liner design. As a result, a Tier 2 analysisprovides a protective design recommendationintended only for use at the user’s site, and isnot intended to be applied to other sites.This section discusses the inputs that a usercan provide and the results from the analysis.

a. Tier 2 Inputs

In addition to the inputs required for theTier 1 analysis, a Tier 2 analysis allows usersto provide additional inputs that account forattributes that are specific to the user’s site.The Tier 2 inputs that are common to theTier 1 evaluation are:

• WMU type—waste pile, surfaceimpoundment, or land applicationunit.

• Chemical constituents of concernpresent in the WMU.

• Leachate concentration (in mg/L) ofeach constituent.

If the user has already performed a Tier 1analysis and continues to a Tier 2 analysis,the Tier 1 inputs are carried forward to theTier 2 analysis. In the Tier 2 analysis, howev-er, the user can change these data withoutchanging the Tier 1 data.

In addition to the Tier 1 inputs, the useralso provides values for additional parametersincluding WMU area, WMU depth for land-fills, ponding depth for surface impound-ments, and the climate center in the IWEMdatabase that is nearest to the site. Theseparameters can have a significant influenceon the LCTVs generated by the model andalso are relatively easy to determine. The useralso has the option to provide values for sev-eral more parameters. Table 8 presents thelist of “required” and “optional” parameters.

Because site-specific data for all of theEPACMTP parameters might not be available,the model contains default values for the

“optional” parameters that are used unlessthe user provides site-specific data. Thedefault values are derived from a number ofsources, including a survey of industrialwaste management units, a hydrogeologicdatabase, water-balance modeling, and valuesreported in the scientific literature. The selec-tion of default values is explained in theIWEM Technical Background Document (U.S.EPA, 2002a). If site-specific data are avail-able, they should be used to derive the mostappropriate design scenario for a particularsite.10

In addition to the above parameters, userscan also enter certain constituent specificproperties, as follows:

• Organic carbon distribution coeffi-cient (KOC). A function of the natureof a sorbent (the soil and its organiccarbon content) and the properties ofa chemical (the leachate constituent).It is equal to the ratio of the solidand dissolved phase concentrations,measured in milliliters per gram(mL/g). The higher the value of thedistribution coefficient, the higherthe adsorbed-phase concentration,meaning the constituent would beless mobile. For metals, IWEM pro-vides an option to enter a site-specif-ic soil-water partition coefficient (Kd),which overrides the MINTEQA2default sorption isotherms.

• DDeeggrraaddaattiioonn ccooeeffffiicciieenntt.. The rate atwhich constituents degrade or decaywithin an aquifer due to biochemicalprocesses, such as hydrolysis orbiodegradation (measured in units of1/year). The default decay rate inIWEM represents degradation fromchemical hydrolysis only, sincebiodegradation rates are stronglyinfluenced by site-specific factors. InTier 2, a user can enter an overall

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10 A Tier 2 evaluation is not always less conservative than a Tier 1. For example, if a site has a very largearea, a very shallow water table, and/or the aquifer thickness is well below the national average, thenthe Tier 2 evaluation results can be more stringent than the Tier 1 analysis results.


Parameter Description Use in Model Units Applicable Required or WMU Optional

WMU area Area covered by the WMU To determine the area for Square meters (m2) All Requiredinfiltration of leachate

WMU location Geographic location of WMU in terms of To determine local climatic Unitless All Requiredthe nearest of 102 climate stations conditions that affect infiltration

and aquifer recharge

Total waste Depth of the unit for landfills (average For landfills, used to determine Meters (m) LF Required for management unit thickness of waste in the landfill, not the landfill depletion rate. For SI landfills and depth counting the thickness of a liner below the surface impoundments, used surface

waste or the thickness of a final cover on as the hydraulic head to derive impoundmentstop of the waste) and surface leakageimpoundments (depth of the free-standing liquid in the impoundment, not counting the thickness of any accumulated sediment layer at the base of the impoundment)

Depth of waste Depth of the base of the unit below the Used together with depth of the Meters (m) LF Optionalmanagement unit ground surface water table to determine SI below ground distance leachate has to travel WPsurface through unsaturated zone to

reach ground water

Surface Thickness of sediment at the base of Limits infiltration from unit. Meters (m) SI OptionalImpoundment surface impoundment (discounting sediment layer thickness of engineered liner, if present)thickness

WMU operational Period of time WMU is in operation. IWEM assumes leachate Years WP Optionallife generation occurs over the same SI

period of time. LAU

WMU infiltration Rate at which leachate flows from the Affected by area’s rainfall Meters per year All Optionalrate bottom of a WMU (including any liner) intensity and design (m/yr)

into unsaturated zone performance. Users either input infiltration rates directly or allow IWEM to estimate values based on the unit’s geographic location,11 liner design, cover design and WMU type.

Soil type Predominant soil type in the vicinity of Uses site-specific soil data to sandy loam All Optionalthe WMU model leachate migration silt loam

through unsaturated zone and silty clay loamdetermine regional recharge rate

Distance to a well The distance from a WMU to a To determine the horizontal Meters (m) All Optionaldowngradient well. distance over which dilution

and attenuation occur.

Hydrogeological Information on the hydrogeological setting Determines certain aquifer Varies All Optionalsetting of the WMU characteristics (depth to water

table, saturated zone thickness, saturated zone hydraulic conductivity, ground-water hydraulic gradient) when complete information not available

Table 8.Input Parameters for Tier 2


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11 For surface impoundments IWEM can use either the unit’s geographic location or impoundment characteristics(such as ponding depth, and thickness of sediment layer) to estimate the infiltration rates.

degradation rate which overrides theIWEM default. A user can choose toinclude degradation due to hydroly-sis and biodegradation in the overalldegradation rate.

b. Tier 2 Results

After providing site-specific inputs, theuser generates design recommendations foreach constituent by launching EPACMTPfrom within IWEM. EPACMTP will then sim-ulate the site and determine the 90th per-centile exposure concentration for eachdesign scenario. IWEM determines the mini-mum recommended design at a 90th per-centile exposure concentration by performing10,000 Monte Carlo simulations ofEPACMTP for each waste constituent anddesign. Upon completion of the modelinganalyses, IWEM will display the minimumdesign recommendation and the calculated,location-specific LCTVs based on the 90thpercentile exposure concentration.

The overall result of a Tier 2 analysis is adesign recommendation similar to the Tier 1analysis. However, the basis for the recom-mendation differs slightly. To illustrate thesimilarities and differences between theresults from the two tiers, the remainder ofthis section continues the example Tier 1evaluation through a Tier 2 evaluation. In theTier 1 example, the disposal of toluene andstyrene in a proposed landfill is evaluated.The expected leachate concentration fortoluene is 1.6 mg/L and the expectedleachate concentration for styrene is 1.0mg/L. In Tier 2, after inputting the site-spe-cific data summarized in Table 9 and usingdefault data for the remaining parameters,the user can then launch the EPACMTPmodel simulations.

After completing the EPACMTP modelsimulations, IWEM produces the results onscreen. Table 10 presents the detailed resultsof a Tier 2 analysis for the no liner/in situsoils scenario. The data presented in thistable are similar to the data presented in theTier 1 results, but the Tier 2 analysis expands

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Parameter Description Use in Model Units Applicable Required or WMU Optional

Depth to the water The depth of the zone between the land Used to predict travel time. Meters (m) All Optionaltable surface and the water table

Saturated zone Thickness of the saturated zone of the Delineates the depth over Meters (m) All Optionalthickness aquifer which leachates can mix with

ground waters.

Saturated zone Hydraulic conductivity of the saturated With hydraulic gradient, used Meters per year All Optionalhydraulic zone, or the permeability of the saturated to calculate ground-water flow (m/yr)conductivity zone in the horizontal direction. rates.

Ground-water Regional horizontal ground-water gradient With hydraulic conductivity, Meters per meter All Optionalhydraulic gradient used to calculate the ground- (m/m)

water flow rate.

Distance to nearest The distance from the unit to the nearest Affects the calculation of Meters (m) SI Optionalsurface water body water body ground-water mounding at a site.

Table 8.Input Parameters for Tier 2 (con’t)

the information provided tothe user. It includes additionalinformation regarding the tox-icity standard, the referenceground-water concentration(RGC), and the 90th per-centile exposure concentra-tion. The toxicity standard isincluded because the user canselect specific standards, pro-vide a user-defined standard,or compare to all standards. Inthis example, all standardswere selected; the user canidentify the result for eachstandard from a single table.The LCTV continues to repre-sent the maximum leachate


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Parameters Site-Specific Data

Infiltration rate* Local climate: Madison, WISoil type: fine-grained soil

Waste management unit area 15,000 m2

Waste management unit depth 2 m

Depth to the water table 10 m

Aquifer thickness 25 m

Toxicity standards Compare to all

Distance to a well 150 m

Table 9.

A Sample Set of Site-Specific Data for Input to Tier 2

* The Tier 2 model uses an infiltration rate for the liner scenarios

based on local climate and soil data.

CAS # Constituent Leachate DAF LCTV Toxicity Ref. 90th Percentile Protective?Concentration (mg/L) Standard Ground- Exposure

(mg/L) water ConcentrationConc. (mg/L) (mg/L)

100-42-5 Styrene 1.0 8.3 0.83 MCL 0.1 0.1201 No

100-42-5 Styrene 1.0 8.3 29.88 HBN - 3.6 0.1201 YesIngestion

Non- Cancer

100-42-5 Styrene 1.0 8.3 40.67 HBN - 4.9 0.1201 YesInhalation

Non- cancer

108-88-3 Toluene 1.6 8.3 8.3 MCL 1 0.1922 Yes

108-88-3 Toluene 1.6 8.4 10.92 HBN - 1.3 0.1894 YesIngestion

Non- cancer

108-88-3 Toluene 1.6 8.4 41.16 HBN - 4.9 0.1894 YesInhalation

Non- cancer

Table 10:

Example of Tier 2 Detailed Summary Table - No Liner/In situ Soils

concentration for a design scenario that isstill protective for a reference ground-waterconcentration, but the LCTV is not the basisfor the design recommendation.

The RGC and 90th percentile exposureconcentration are provided because they arethe point of comparison for the Tier 2 analy-sis. (The LCTV, however, continues to provideinformation about a threshold that might beuseful for pollution prevention or waste mini-mization efforts.) As shown in Table 10, theno liner/in situ soils scenario is protective fortoluene because all of the 90th percentileexposure concentrations are less than thethree RGCs for toluene, while the no liner/insitu soils scenario is not protective for styrenefor the MCL comparison. For that standard,the 90th percentile exposure concentration(0.1201 mg/L) exceeds the RGC (0.1 mg/L).In this case, IWEM would launch EPACMTPto evaluate a clay liner to determine whetherthat liner design would be protective.

Table 11 provides the single clay linerresults for a Tier 2 analysis. As shown in thetable, the single clay liner is protectivebecause the 90th percentile exposure concen-tration (0.0723 mg/L) is less than the refer-

ence ground-water concentration (0.1 mg/L).In addition, under the “Protective?” column,IWEM refers the user to the appropriate linerresult if a less stringent design is recom-mended. In Table 11, the user is referred tothe no liner/in situ soils results for the HBN-based ingestion and inhalation resultsbecause, as shown in Table 10, the noliner/in situ soils scenario is protective. If aTier 2 analysis determines that a single clayliner is protective for all constituents, thenIWEM would not continue to an evaluationof a composite liner. For this example ofstyrene and toluene disposed of in a landfill,the recommended minimum design is a sin-gle clay liner, because the 90th percentileexposure concentration (0.0723) is less thanthe MCL-based RGC (0.1).

2. What Do the Results Meanand How Do I Interpret Them?

The Tier 2 analysis provides LCTVs andrecommendations for a minimum protectivedesign. In the Tier 1 analysis, that recommen-dation is based on a comparison of expectedleachate concentrations to LCTVs to determinewhether a design scenario is protective. In the

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CAS # Constituent Leachate DAF LCTV Toxicity Ref. 90th Percentile Protective?Concentration (mg/L) Standard Ground- Exposure

(mg/L) water ConcentrationConc. (mg/L) (mg/L)

100-42-5 Styrene 1.0 14 1.4 MCL 0.1 0.0723 Yes

100-42-5 Styrene 1.0 14 50.4 HBN - 3.6 0.0722 See No liner Ingestion Results

Non- Cancer

100-42-5 Styrene 1.0 14 68.6 HBN - 4.9 0.0722 See No liner Inhalation Results

Non- cancer

Table 11:

Example of Tier 2 Detailed Summary Table - Single Clay Liner

Tier 2 analysis, LCTVs can be used to helpwaste managers determine whether waste min-imization techniques might lower leachateconcentrations and enable them to use lesscostly unit designs, but IWEM does not needto calculate an LCTV to make a design recom-mendation. If the 90th percentile ground-water concentration does not exceed thespecified RGC, then the evaluated design sce-nario is protective for that constituent. If the90th percentile ground-water concentrationsfor all constituents under the no liner/in situsoils scenario are below their respective RGCs ,then IWEM will recommend that no liner/insitu soils is needed to protect the groundwater. If the 90th percentile ground-water con-centration of any constituent exceeds its RGC,then a single clay liner is recommended (or, inthe case of land application units, land appli-cation is not recommended). Similarly, if the90th percentile ground-water concentration ofany constituent under the single clay liner sce-nario exceeds its RGC, then a composite lineris recommended. As previously noted, howev-er, you may decide to conduct a Tier 3 site-specific analysis to determine which designscenario is most appropriate. See the ensuingsection on Tier 3 analyses for further informa-tion. For waste streams with multiple con-stituents, the most protective liner design thatis recommended for any one constituent is theoverall recommendation. As in the Tier 1 eval-uation, pollution prevention, recycling, andtreatment practices could be considered whenthe protective standard of a composite liner isexceeded if you decide not to undertake a Tier3 assessment to reflect site-specific conditions.

If the Tier 2 analysis found land applica-tion to be appropriate for the constituents ofconcern, then a new land application systemmay be considered (after evaluating other fac-tors). Alternatively, if the waste has one ormore “problem” constituents that make landapplication inappropriate, the user mightconsider pollution prevention, recycling, and

treatment options for those constituents. If,after conducting the Tier 2 evaluation, theuser is not satisfied with the resulting recom-mendations, or if site-specific conditionsseem likely to suggest a different conclusionregarding the appropriateness of land applica-tion of a waste, then the user can conduct amore in-depth, site-specific, ground-waterrisk analysis (Tier 3).

In addition to the Tier 2 evaluation, otherfate and transport models have been devel-oped that incorporate location-specific consid-erations, such as the American PetroleumInstitute’s (API’s) Graphical Approach forDetermining Site-Specific Dilution-AttenuationFactors.12 API developed its approach to calcu-late facility-specific DAFs quickly usinggraphs rather than computer models. Graphsvisually indicate the sensitivity to variousparameters. This approach can be used forimpacted soils located above or within anaquifer. This approach accounts for attenua-tion with distance and time due toadvective/dispersive processes. API’s approachhas a preliminary level of analysis that uses asmall data set containing only measures of theconstituent plume’s geometry. The user canread other necessary factors off graphs provid-ed as part of the approach. This approach alsohas a second level of analysis in which theuser can expand the data set to include site-specific measures, such as duration of con-stituent leaching, biodegradation ofconstituents, or site-specific dispersivity val-ues. At either level of analysis, the calculationresults in a DAF. This approach is not appro-priate for all situations; for example, it shouldnot be used to estimate constituent concentra-tions in active ground-water supply wells orto model very complex hydrogeologic set-tings, such as fractured rock. It is recom-mended that you consult with the appropriatestate agency to discuss the applicability of theAPI approach or any other location-adjustedmodel prior to use.


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12 A copy of API’s user manual, The Technical Background Document and User Manual (API Publication 4659),can be obtained from the American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005,202 682-8375.

D. Strengths andLimitations

Listed below are some of IWEM’s strengthsand limitations that the user should be aware of:

1. Strengths• The tool is relatively easy to use and

requires a minimal amount of dataand modeling expertise.

• The tool can perform rapid Tier 1screening evaluations. Tier 2 evalua-tions allow for many site-specificadjustments.

• The tool is designed to be flexiblewith respect to the availability of site-specific data for a Tier 2 evaluation.The user needs to provide only asmall number of inputs, but if moredata are available, the tool canaccommodate their input.

• Users can enter their own infiltrationrates to evaluate additional designscenarios and still use IWEM to con-duct a risk evaluation.

• The user can modify RGC values,when appropriate, and in consulta-tion with other stakeholders.

• The user can modify properties ofthe 226 constituents (e.g., addingbiodegradation), and can add addi-tional constituents for evaluation.

• The tool provides recommendationsfor protective design systems. It canalso be used to evaluate whetherwaste leachate reduction measureswould be appropriate.

2. Limitations• IWEM considers only exposures

from contact with contaminated

ground water via ingestion of drink-ing water and inhalation while show-ering. IWEM does not considervapor intrusion into buildings. It alsodoes not address potential risksthrough environmental pathwaysother than ground water, such asvolatile emissions from a WMU, sur-face runoff and erosion, and indirectexposures through the food chainpathway. Other chapters in thisGuide, however, address ways toassess or control potential risks viasuch other pathways.

• The use of a waste concentration toleachate concentration ratio of10,000 in IWEM Tier 2 may overesti-mate the amount of contaminantmass in the WMU, allowing themodeling results to approach non-depleting source steady-state valuesfor WMUs without engineered liners.This may result in an underestima-tion of the Tier 2 LCTVs.

• IWEM considers only human healthrisks. Exposure and risk to ecologicalreceptors are not included.

• The conceptual flow model used inEPACMTP in conjunction withIWEM Tier 2 data input constraintsmight produce ground-water veloci-ties that might be greater than can beassumed based on the site-specifichydraulic conductivity and hydraulicgradient values. The maximum val-ues that the velocities can reach arelimited by a model constraint thatappropriately prevents the modeledwater level from rising above theground surface. Despite this con-straint, modeled velocities might begreater than expected velocities basedon site-specific hydraulic conductivi-ty and hydraulic gradient.

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• The risk evaluation in IWEM is basedon the ground-water concentration ofindividual waste constituents. IWEMdoes not address the cumulative riskdue to simultaneous exposure to mul-tiple constituents (although it doesuse a carcinogenic risk level at theconservative end of EPA’s risk range).

• IWEM is not designed for sites withcomplex hydrogeology, such as frac-tured (karst) aquifers.

• The tool is inappropriate for siteswhere non-aqueous phase liquid(NAPL) contaminants are present.

• IWEM does not account for all possi-ble fate and transport processes. Forexample, colloid transport might beimportant at some sites but is notconsidered in IWEM. While the usercan enter a constituent-specificdegradation rate constant to accountfor biodegradation, IWEM simulatesbiodegradation in a relatively simpleway by assuming the rate is the samein both the unsaturated and the satu-rated zones.

E. Tier 3: A ComprehensiveSite-Specific Evaluation

If the Tier 1 and Tier 2 evaluations do notadequately simulate conditions at a proposedsite, or if you decide that sufficient data areavailable to skip a Tier 1 or Tier 2 analysis, asite-specific risk assessment could be consid-ered.13 In situations involving a complexhydrogeologic setting or other site-specificfactors that are not accounted for in IWEM, adetailed site-specific ground-water fate andtransport analysis might be appropriate fordetermining risk to ground water and evalu-ating alternative designs or application rates.It is recommended that you consult with theappropriate state agency and use a qualified

professional experienced in ground-watermodeling. State officials and appropriatetrade associations might be able to suggest agood consultant to perform the analysis.

1. How is a Tier 3 EvaluationPerformed?

A Tier 3 evaluation will generally involve amore detailed site-specific analysis than Tier2. Sites for which a Tier 3 evaluation mightbe performed typically involve complex andheterogeneous hydrogeology. Selection andapplication of appropriate ground-watermodels require a thorough understanding ofthe waste and the physical, chemical, andhydrogeologic characteristics of the site.

A Tier 3 evaluation should involve the fol-lowing steps:

• Developing a conceptual hydrogeo-logical model of the site.

• Selecting a flow and transport simu-lation model.

• Applying the model to the site.


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13 For example, if ground-water flow is subject to seasonal variations, use of the Tier 2 evaluation toolmight not be appropriate because the model is based on steady-state flow conditions.

Why is it important to usea qualified professional?• Fate and transport modeling can be

very complex; appropriate trainingand experience are required to cor-rectly use and interpret models.

• Incorrect fate and transport modelingcan result in a liner system that is notsufficiently protective or an inappro-priate land application rate.

• To avoid incorrect analyses, check tosee if the professional has sufficienttraining and experience at analyzingground-water flow and contaminantfate and transport.

As with all modeling, you should consultwith the state before investing significantresources in a site-specific analysis. The statemight have a list of preferred models andmight be able to help plan the fate and trans-port analysis.

a. Developing a ConceptualHydrogeological Model

The first step in the site-specific Tier 3evaluation is to develop a conceptual hydro-geological model of the site. The conceptualmodel should describe the key features andcharacteristics to be captured in the fate andtransport modeling. A complete conceptualhydrogeological model is important to ensurethat the fate and transport model can simu-late the important features of the site. Theconceptual hydrogeological model shouldaddress questions such as:

• Does a confined aquifer, an uncon-fined aquifer, or both need to be sim-ulated?

• Does the ground water flow throughporous media, fractures, or a combi-nation of both?

• Is there single, or are there multiple,hydrogeologic layers to be simulated?

• Is the hydrogeology constant or vari-able in layer thickness?

• Are there other hydraulic sources orsinks (e.g., extraction or injectionwells, lakes, streams, ponds)?

• What is the location of natural no-flow boundaries and/or constanthead boundaries?

• How significant is temporal (season-al) variation in ground-water flowconditions? Does it require a tran-sient flow model?

• What other contaminant sources arepresent?

• What fate processes are likely to besignificant (e.g. sorption andbiodegradation)?

• Are plume concentrations highenough to make density effects sig-nificant?

b. Selecting a Fate and TransportSimulation Model

Numerous computer models exist to simu-late ground-water fate and transport.Relatively simple models are often based onanalytical solutions of the mathematicalequations governing ground-water flow andsolute transport equations. However, suchmodels generally cannot simulate the com-plexities of real world sites, and for a rigor-ous Tier 3 evaluation, numerical modelsbased on finite-difference or finite-elementtechniques are recommended. The primarycriteria for selecting a particular modelshould be that it is consistent with the char-acteristics of the site, as described in the con-ceptual site hydrogeological model, and thatit is able to simulate the significant processesthat control contaminant fate and transport.

In addition to evaluating whether a modelwill adequately address site characteristics,the following questions should be answeredto ensure that the model will provide accu-rate, verifiable results:

• What is the source of the model?How easy is it to obtain and is themodel well documented?

• Are documentation and user’s manu-als available for the model? If yes, arethey clearly written and do they pro-vide sufficient technical backgroundon the mathematical formulation andsolution techniques?

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• Has the model been verified againstanalytical solutions and other mod-els? If yes, are the test cases availableso that a professional consultant cantest the model on his/her computersystem?

• Has the model been validated usingfield data?

Table 12 provides a brief description of anumber of commonly used ground-water fateand transport models.

c. Applying the Model to the Site

For proper application of a ground-waterflow and transport model, expertise in hydro-

geology and the principles of flow and trans-port, as well as experience in using modelsand interpreting model results are essential.The American Society for Testing and Materials(ASTM) has developed guidance that might beuseful for conducting modeling. A listing ofguidance material can be found in Table 13.

The first step in applying the model to asite is to calibrate it. Model calibration is theprocess of matching model predictions toobserved data by adjusting the values ofinput parameters. In the case of ground-watermodeling, the calibration is usually done bymatching predicted and observed hydraulichead values. Calibration is important even forwell-characterized sites, because the values ofmeasured or estimated model parameters arealways subject to uncertainty. Calibrating theflow model is usually achieved by adjustingthe value(s) of hydraulic conductivity andrecharge rates. In addition, if plume monitor-ing data or tracer test data are available,transport parameters such as dispersivity, andsorption and degradation parameters can alsobe calibrated. A properly calibrated model isa powerful tool for predicting contaminantfate and transport. Conversely, if no calibra-tion is performed due to lack of suitable sitedata, any Tier 3 model predictions willremain subject to considerable uncertainty.

At a minimum, a site-specific analysisshould provide estimated leachate concentra-tions at specified downgradient points for aproposed design. For landfills, surfaceimpoundments and waste piles, you shouldcompare these concentrations to appropriateMCLs, health-based standards, or state stan-dards. For land application units, if a wasteleachate concentration is below the valuesspecified by the state, land application mightbe appropriate. Conversely, if a leachate con-centration is above state-specified values,land application might not be protective ofthe ground water.


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What are some useful resources forselecting a ground-water fate andtransport model?

The following resources can helpselect appropriate modeling software:

• Ground Water Modeling Compendium,Second Edition (U.S. EPA, 1994c)

• Assessment Framework for Ground-Water Modeling Applications (U.S. EPA,1994b)

• Technical Guide to Ground-water ModelSelection at Sites Contaminated withRadioactive Substances (U.S. EPA,1994a)

• EPA’s Center for Subsurface ModelingSupport (CSMoS—RSKERL; Ada,Oklahoma)

• Anderson, Mary P. and William W.Woessner. Applied GroundwaterModeling: Simulation of Flow andAdvective Transport (Academic Press,1992)

• EPA regional offices

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Model Name Description

MODFLOW MODFLOW is a 3-D, ground-water flow model for steady state and transient simulation ofsaturated flow problems in confined and unconfined aquifers. It calculates flow rates andwater balances. The model includes flow towards wells, through riverbeds, and into drains.MODFLOW is the industry standard for ground-water modeling that was developed andstill maintained by the United States Geological Survey (USGS). MODFLOW-2000 is thecurrent version. MODFLOW is a public domain model; numerous pre- and post-processingsoftware packages are available commercially. MODFLOW can simulate ground-water flowonly. In order to simulate contaminant transport, MODFLOW must be used in conjunctionwith a compatible solute transport model (MT3DMS, see below).

MODFLOW and other USGS models can be obtained from the USGS Web site at<water.usgs.gov/nrp/gwsoftware/modflow.html>.

MT3DMS Modular 3-D Transport model (MT3D) is commonly used in contaminant transport model-ing and remediation assessment studies. Originally developed for EPA, the current version isknown as MT3DMS. MT3DMS has a comprehensive set of options and capabilities for sim-ulating advection, dispersion/diffusion, and chemical reactions of contaminants in ground-water flow systems under general hydrogeologic conditions. MT3DMS retains the samemodular structure of the original MT3D code, similar to that implemented in MODFLOW.The modular structure of the transport model makes it possible to simulate advection, dis-persion/diffusion, source/sink mixing, and chemical reactions separately without reservingcomputer memory space for unused options. New packages involving other transportprocesses and reactions can be added to the model readily without having to modify theexisting code.

NOTE: The original version of this model known as MT3D, released in 1991, was based ona mathematical formulation which could result in mass-balance errors. This version shouldbe avoided.

MT3DMS is maintained at the University of Alabama, and can be obtained at:<hydro.geo.ua.edu/mt3d>. MT3DMS is also included, along with MODFLOW, in severalcommercial ground-water modeling software packages.

BIOPLUME-III BIOPLUME-III is a 2-D, finite difference model for simulating the natural attenuation oforganic contaminants in ground water due to the processes of advection, dispersion, sorp-tion, and biodegradation. Biotransformation processes are potentially important in therestoration of aquifers contaminated with organic pollutants. As a result, these processesrequire valuation in remedial action planning studies associated with hydrocarbon contami-nants. The model is based on the USGS solute transport code MOC. It solves the solutetransport equation six times to determine the fate and transport of the hydrocarbons, theelectron acceptors (O2, NO3-, Fe3+, SO4

2-, and CO2), and the reaction byproducts (Fe2+). Anumber of aerobic and anaerobic electron acceptors (e.g., oxygen, nitrate, sulfate, iron (III),and carbon dioxide) have been considered in this model to simulate the biodegradation oforganic contaminants. Three different kinetic expressions can be used to simulate the aero-bic and anaerobic biodegradation reactions.

BIOPLUME-III and other EPA supported ground-water modeling software can be obtainedvia the EPA Center for Subsurface Modeling Support at the RS Kerr Environmental ResearchLab in Ada, Oklahoma: <www.epa.gov/ada/csmos/models.html>.

Table 12.

Example Site-Specific Ground-Water Fate and Transport Models

A well-executed site-specific analysis can bea useful instrument to anticipate and avoidpotential risks. A poorly executed site-specificanalysis, however, could over- or under-emphasize risks, possibly leading to adversehuman health and environmental effects, orcostly cleanup liability, or it could overempha-size risks, possibly leading to the unnecessary

expenditure of limited resources. If possible,the model and the results of the final analyses,including input and output parameters andkey assumptions, should be shared withstakeholders. Chapter 1—Understanding Riskand Building Partnerships provides a moredetailed description of activities to keep thepublic informed and involved.


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The American Society for Testing and Materials (ASTM), Section D-18.21.10 concernssubsurface fluid-flow (ground-water) modeling. The ASTM ground-water modeling sectionis one of several task groups funded under a cooperative agreement between USGS and EPAto develop consensus standards for the environmental industry and keep the modelingcommunity informed as to the progress being made in development of modeling standards.

The standards being developed by D-18.21.10 are “guides” in ASTM terminology, whichmeans that the content is analogous to that of EPA guidance documents. The ASTM mod-eling guides are intended to document the state-of-the-science related to various topics insubsurface modeling.

The following standards have been developed by D-18.21.10 and passed by ASTM.They can be purchased from ASTM by calling 610 832-9585. To order or browse for pub-lications, visit ASTM’s Web site <www.astm.org> .

D-5447 Guide for Application of a Ground-Water Flow Model to a Site-Specific Problem

D-5490 Guide for Comparing Ground-Water Flow Model Simulations to Site-SpecificInformation

D-5609 Guide for Defining Boundary Conditions in Ground-Water Flow Modeling

D-5610 Guide for Defining Initial Conditions in Ground-Water Flow Modeling

D-5611 Guide for Conducting a Sensitivity Analysis for a Ground-Water Flow ModelApplication

D-5718 Guide for Documenting a Ground-Water Flow Model Application

D-5719 Guide to Simulation of Subsurface Air Flow Using Ground-Water FlowModeling Codes

D-5880 Guide for Subsurface Flow and Transport Modeling

D-5981 Guide for Calibrating a Ground-Water Flow Model Application

A compilation of most of the current modeling and aquifer testing standards also can bepurchased. The title of the publication is ASTM Standards on Analysis of HydrologicParameters and Ground Water Modeling, publication number 03-418096-38.

For more information by e-mail, contact [email protected].

Table 13. ASTM Ground-Water Modeling Standards


■■■■ Review the risk characterization tools recommended by this chapter.

■■■■ Characterize the waste in accordance with the recommendations of Chapter 2 — CharacterizingWaste.

■■■■ Obtain expected leachate concentrations for all relevant waste constituents.

■■■■ If a Tier 1 evaluation is conducted, understand and use the Tier 1 Evaluation to obtain recommen-dations for the design of your waste management unit (as noted previously, you can skip the Tier 1analysis and proceed directly to a Tier 2 or Tier 3 analysis).

■■■■ If a design system or other measures are recommended in a Tier 1 analysis, perform a Tier 2 analy-sis if you believe the recommendations are overly protective. Also, if data are available, you canconduct a Tier 2 or Tier 3 analysis without conducting a Tier 1 evaluation.

■■■■ If your site characteristics or your waste management needs are particularly complex, or do notadequately simulate conditions reflected in a Tier 1 or Tier 2 analysis, consult with your state and aqualified professional and consider a more detailed, site-specific Tier 3 analysis.

Assessing Risk Activity List

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7A-41

ASTM. 1996. ASTM Standards on Analysis of Hydrologic Parameters and Ground Water Modeling,Publication Number 03-418096-38.

ASTM. 1993. D-5447 Guide for Application of a Ground-Water Flow Model to a Site-SpecificProblem.

ASTM. 1993. D-5490 Guide for Comparing Ground-Water Flow Model Simulations to Site-specificInformation.

ASTM. 1994. D-5609 Guide for Defining Boundary Conditions in Ground-Water Flow Modeling.

ASTM. 1994. D-5610 Guide for Defining Initial Conditions in Ground-Water Flow Modeling.

ASTM. 1994. D-5611 Guide for Conducting a Sensitivity Analysis for a Ground-Water Flow ModelApplication.

ASTM. 1994. D-5718 Guide for Documenting a Ground-Water Flow Model Application.

ASTM. 1994. D-5719 Guide to Simulation of Subsurface Air Flow Using Ground-Water FlowModeling Codes.

ASTM. 1995. D-5880 Guide for Subsurface Flow and Transport Modeling.

ASTM. 1996. D-5981 Guide for Calibrating a Ground-Water Flow Model Application.

Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills.

Berner, E. K. and R. Berner. 1987. The Global Water Cycle: Geochemistry and Environment.

Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention,and Remediation.

Lee, C. 1992. Environmental Engineering Dictionary, 2d. Ed.

Sharma, H., and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and Landfills.

Speidel, D., L. Ruedisili, and A. Agnew. 1988. Perspectives on Water: Uses and Abuses.

Resources


Resources (cont.)


U.S. EPA. 2002a. Industrial Waste Management Evaluation Model (IWEM) TechnicalBackground Document. EPA530-R-02-012.

U.S. EPA. 2002b. The User’s Guide for the Industrial Waste Management Evaluation Model.EPA530-R- 02-013.

U.S. EPA. 2002c. EPACMTP Data/Parameters Background Document.

U.S. EPA. 2002d. EPACMTP Technical Background Document.

U.S. EPA. 1997a. Exposure Factors Handbook. EPA600-P-95-002F.

U.S. EPA. 1997b. Guiding Principles for Monte Carlo Analyses. EPA630-R-97-001.

U.S. EPA. 1994a. A Technical Guide to Ground-Water Model Selection at Sites Contaminatedwith Radioactive Substance. EPA 4-2-R-94-012.

U.S. EPA. 1994b. Assessment Framework for Ground-Water Modeling Applications. EPA500-B-94-003.

U.S. EPA. 1994c. Ground-Water Modeling Compendium, Second Edition. EPA500-B-94-003.

U.S. EPA. 1991. Seminar Publication: Site Characterization for Subsurface Remediation.EPA625-4-91-026.

U.S. EPA. 1989. Exposure Assessment Methods Handbook.

U.S. EPA. 1988. Selection Criteria For Mathematical Models Used In Exposure Assessments:Ground-water Models. EPA600-8-88-075.

U.S. EPA. 1988. Superfund Exposure Assessment Manual.

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Part IVProtecting Ground Water

Chapter 7: Section BDesigning and Installing Liners

Technical Considerations for New SurfaceImpoundments, Landfills, and Waste Piles

Contents

I. In-Situ Soil Liners ..................................................................................................................................7B-1

II. Single Liners ..........................................................................................................................................7B-2

A. Compacted Clay Liners ........................................................................................................................7B-2

B. Geomembranes or Flexible Membrane Liners ....................................................................................7B-10

C. Geosynthetic Clay Liners ....................................................................................................................7B-17

III. Composite Liners ..................................................................................................................................7B-22

IV. Double Liners (Primary and Secondary Lined Systems) ........................................................................7B-23

V. Leachate Collection and Leak Detection Systems ..................................................................................7B-24

A. Leachate Collection System..................................................................................................................7B-24

B. Leak Detection System ........................................................................................................................7B-28

C. Leachate Treatment System ..................................................................................................................7B-29

VI. Construction Quality Assurance and Quality Control ..........................................................................7B-29

A. Compacted Clay Liner Quality Assurance and Quality Control ..........................................................7B-32

B. Geomembrane Liner Quality Assurance and Quality Control ..............................................................7B-32

C. Geosynthetic Clay Liner Quality Assurance and Quality Control ........................................................7B-33

D. Leachate Collection System Quality Assurance and Quality Control ....................................................7B-34

Designing and Installing Liners Activity List................................................................................................7B-36

Resources ....................................................................................................................................................7B-37

Appendix ....................................................................................................................................................7B-43

Figures:

Figure 1. Water Content for Achieving a Specific Density ..........................................................................7B-6

Figure 2: Two Types of Footed Rollers........................................................................................................7B-8

Figure 3: Four Variations of GCL Bonding Methods ................................................................................7B-19

Figure 4: Typical Leachate Collection System ..........................................................................................7B-25

Figure 5: Typical Geonet Configuration....................................................................................................7B-27

Protecting Ground Water—Designing and Installing Liners

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Once risk has been characterizedand the most appropriatedesign system is chosen, thenext step is unit design. TheIndustrial Waste Management

Evaluation Model (IWEM), discussed inChapter 7, Section A—Assessing Risk can beused to determine appropriate design systemrecommendations. A critical part of thisdesign for new landfills, waste piles, and sur-face impoundments is the liner system. Theliner system recommendations in the Guidedo not apply to land application units, sincesuch operations generally do not include aliner system as part of their design. (Fordesign of land application units, refer toChapter 7, Section C—Designing a LandApplication Program.) You should work withyour state agency to ensure consideration ofany applicable design system requirements,recommendations, or standard practices thestate might have. In this chapter, sections Ithough IV discuss four design options—noliner/in-situ soils, single liner, composite liner,and double liner. Section V covers leachatecollection and leak detection systems, andsection VI discusses construction qualityassurance and quality control.

I. In-Situ SoilLiners

For the purpose of the Guide, in-situ soilrefers to simple, excavated areas or impound-ments, without any additional engineeringcontrols. The ability of natural soils to hindertransport and reduce the concentration ofconstituent levels through dilution and atten-uation can provide sufficient protection whenthe initial constituent levels in the wastestream are very low, when the wastes areinert, or when the hydrogeologic settingaffords sufficient protection.

What are the recommendations

for in-situ soils?

The soil below and adjacent to a wastemanagement unit should be suitable for con-struction. It should provide a firm foundationfor the waste. Due to the low risk associatedwith wastes being managed in these units, aliner might not be necessary; however, it isstill helpful to review the recommended loca-tion considerations and operating practices forthe unit.

Designing and Installing Liners—TechnicalConsiderations for New Surface

Impoundments, Landfills, and Waste PilesThis chapter will help you:

• Employ liner systems where needed to protect ground water from

contamination.

• Select from clay liners, synthetic liners, composite liners, leachate

collection systems, and leak detection systems as appropriate.

• Consider technical issues carefully to ensure that the liner system

will function as designed.

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1 Many industry and trade periodicals, such as Waste Age, MSW Management, Solid Waste Technologies,and World Wastes, have articles on liner types and their corresponding costs, as well as advertisementsand lists of vendors.

What technical issues should be

considered with the use of in-situ

soils?

In units using in-situ natural soils, con-struction and design of an engineered linerwill not be necessary; however, there are stilltechnical concerns to consider. These includethe following:

• The stability of foundation soils.

• The compatibility of the waste withnative soils.

• The location where the unit will besited.

• The potential to recompact existingsoils.

Potential instability can occur in the foun-dation soil, if its load-bearing capacity andresistance to movement or consolidation areinsufficient to support the waste. The ground-water table or a weak soil layer also can influ-ence the stability of the unit. You should takemeasures, such as designing maximum slopes,to avoid slope failure during construction andoperation of the waste management unit. Mostsoil slopes are stable at a 3:1 horizontal to ver-tical inclination. There are common senseoperating practices to ensure that any wastesto be managed on in-situ soils will not inap-propriately interact with the soils. When usingin-situ soils, refer to Chapter 4—Consideringthe Site. Selecting an appropriate location willbe of increased importance, since the addedbarrier of an engineered liner will not be pre-sent. Because in-situ soil can have non-homo-geneous material, root holes, and cracks, itsperformance can be improved by scarifyingand compacting the top portion of the in-situnatural soils.

II. Single LinersIf the risk evaluation recommended the use

of a single liner, the next step is to determinethe type of single liner system most appropri-ate for the site. The discussion below address-es three types of single liner systems:compacted clay liners, geomembrane liners,and geosynthetic clay liners. Determiningwhich material, or combination of materials, isimportant for protecting human health andthe environment.1

A. Compacted Clay Liners A compacted clay liner can serve as a single

liner or as part of a composite or double linersystem. Compacted clay liners are composedof natural mineral materials (natural soils),bentonite-soil blends, and other materialsplaced and compacted in layers called lifts. Ifnatural soils at the site contain a significantquantity of clay, then liner materials can beexcavated from onsite locations known as bor-row pits. Alternatively, if onsite soils do notcontain sufficient clay, clay materials can behauled from offsite sources, often referred toas commercial pits.

Compacted clay liners can be designed towork effectively as hydraulic barriers. Toensure that compacted clay liners are wellconstructed and perform as they are designed,it is important to implement effective qualitycontrol methods emphasizing soil investiga-tions and construction practices. Three objec-tives of quality assurance and quality controlfor compacted soil liners are to ensure that 1)selected liner materials are suitable, 2) linermaterials are properly placed and compacted,and 3) the completed liner is properly protect-ed before, during, and after construction.Quality assurance and quality control are dis-cussed in greater detail in section VI.

What are the thickness and

hydraulic conductivity recommen-

dations for compacted clay liners?

Compacted clay liners should be at least 2feet thick and have a maximum hydraulicconductivity of 1 x 10-7 cm/sec (4 x 10-8

in/sec). Hydraulic conductivity refers to thedegree of ease with which a fluid can flowthrough a material. A low hydraulic conduc-tivity will help minimize leachate migrationout of a unit. Designing a compacted clayliner with a thickness ranging from 2 to 5 feetwill help ensure that the liner meets desiredhydraulic conductivity standards and willalso minimize leachate migration as a resultof any cracks or imperfections present in theliner. Thicker compacted clay liners provideadditional time to minimize leachate migra-tion prior to the clay becoming saturated.

What issues should be considered

in the design of a compacted clay

liner?

The first step in designing a compactedclay liner is selecting the clay material. Thequality and properties of the material willinfluence the performance of the liner. Themost common type of compacted soil is onethat is constructed from naturally occurringsoils that contain a significant quantity ofclay. Such soils are usually classified as CL,CH, or SC in the Unified Soil ClassificationSystem (USCS). Some of the factors to con-sider in choosing a soil include soil proper-ties, interaction with wastes, and test resultsfor potentially available materials.

Soil PropertiesMinimizing hydraulic conductivity is the

primary goal in constructing a soil liner.Factors to consider are water content, plasticitycharacteristics, percent fines, and percent grav-el, as these properties affect the soil’s ability toachieve a specified hydraulic conductivity.

Hydraulic conductivity. It is important toselect compacted clay liner materials so thatremolding and compacting of the materialswill produce a low hydraulic conductivity.Factors influencing the hydraulic conductivi-ty at a particular site include: the degree ofcompaction, compaction method, type of claymaterial used, soil moisture content, anddensity of the soil during liner construction.The hydraulic conductivity of a soil alsodepends on the viscosity and density of thefluid flowing through it. Consider measuringhydraulic conductivity using methods such asAmerican Society of Testing and Materials(ASTM) D-5084.2

Water content. Water content refers to theamount of liquid, or free water, contained in agiven amount of material. Measuring watercontent can help determine whether a claymaterial needs preprocessing, such as moistureadjustment or soil amendments, to yield aspecified density or hydraulic conductivity.Compaction curves can be used to depictmoisture and density relationships, usingeither ASTM D-698 or ASTM D-1557, thestandard or modified Proctor test methods,depending on the compaction equipment usedand the degree of firmness in the foundationmaterials.3 The critical relationship betweenclay soil moisture content and density isexplained thoroughly in Chapter 2 of EPA’s1993 technical guidance document Quality


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2 ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated PorousMaterials Using a Flexible Wall Permeameter.

3 ASTM D-698, Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort(12,400 ft-lbf/ft3 (600 kN-m/m3)).ASTM D-1557, Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort(56,000 ft-lbf/ft3 (2,700 kN-m/m3)).

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Assurance and Quality Control for WasteContainment Facilities (U.S. EPA, 1993c).

Plasticity characteristics. Plasticity char-acteristics describe a material’s ability tobehave as a plastic or moldable material.Soils containing clay are generally categorizedas plastic. Soils that do not contain clay arenon-plastic and typically considered unsuit-able materials for compacted clay liners,unless soil amendments such as bentoniteclay are introduced.

Plasticity characteristics are quantified bythree parameters: liquid limit, plastic limit,and plasticity index. The liquid limit isdefined as the minimum moisture content (inpercent of oven-dried weight) at which a soil-water mixture can flow. The plastic limit isthe minimum moisture content at which asoil can be molded. The plasticity index isdefined as the liquid limit minus the plasticlimit and defines the range of moisture con-tent over which a soil exhibits plastic behav-ior. When soils with high plastic limits aretoo dry during placement, they tend to formclods, or hardened clumps, that are difficultto break down during compaction. As aresult, preferential pathways can form aroundthese clumps allowing leachate to flowthrough the material at a higher rate. Soilplasticity indices typically range from 10 per-cent to 30 percent. Soils with a plasticityindex greater than 30 percent are cohesive,sticky, and difficult to work with in the field.Common testing methods for plasticity char-acteristics include the methods specified inASTM D-4318, also known as Atterberg lim-its tests.4

Percent fines and percent gravel. Typicalsoil liner materials contain at least 30 percentfines and can contain up to 50 percent gravel,by weight. Common testing methods for per-cent fines and percent gravel are specified inASTM D-422, also referred to as grain sizedistribution tests.5 Fines refer to silt and clay-

sized particles. Soils with less than 30 percentfines can be worked to obtain hydraulic con-ductivities below 1 x 10-7 cm/sec (4 x 10-8

in./sec), but use of these soils requires morecareful construction practices.

Gravel is defined as particles unable topass through the openings of a Number 4sieve, which has an opening size equal to4.76 mm (0.2 in.). Although gravel itself hasa high hydraulic conductivity, relatively largeamounts of gravel, up to 50 percent byweight, can be uniformly mixed with claymaterials without significantly increasing thehydraulic conductivity of the material. Claymaterials fill voids created between gravelparticles, thereby creating a gravel-clay mix-ture with a low hydraulic conductivity. Aslong as the percent gravel in a compactedclay mixture remains below 50 percent, cre-ating a uniform mixture of clay and gravel,where clay can fill in gaps, is more criticalthan the actual gravel content of the mixture.

You should pay close attention to the per-cent gravel in cases where a compacted clayliner functions as a bottom layer to a geosyn-thetic, as gravel can cause puncturing ingeosynthetic materials. Controlling the maxi-mum particle size and angularity of the grav-el should help prevent puncturing, as well asprevent gravel from creating preferential flowpaths. Similar to gravel, soil particles or rockfragments also can create preferential flowpaths. To help prevent the development ofpreferential pathways and an increasedhydraulic conductivity, it is best to use soilliner materials where the soil particles androck fragments are typically small (e.g., 3/4inch in diameter).

Interactions With WasteWaste placed in a unit can interact with

compacted clay liner materials, thereby influ-encing soil properties such as hydraulic con-

4 ASTM D-4318, Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.

5 ASTM D-422, Standard Test Method for Particle-Size Analysis of Soils.


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6 SW-846, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods.

ductivity and permeability. Two ways thatwaste materials can influence the hydraulicconductivity of the liner materials arethrough dissolution of soil minerals andchanges in clay structure. Soil minerals canbe dissolved, or reduced to liquid form, as aresult of interaction with acids and bases. Forexample, aluminum and iron in the soil canbe dissolved by acids, and silica can be dis-solved by bases. While some plugging of soilpores by dissolved minerals can lowerhydraulic conductivity in the short term, thecreation of piping and channels over time canlead to an increased hydraulic conductivity inthe long term. The interaction of waste andclay materials can also cause the creation ofpositive ions, or cations. The presence ofcations such as sodium, potassium, calcium,and magnesium can change the clay struc-ture, thereby influencing the hydraulic con-ductivity of the liner. Depending on thecation type and the clay mineral, an increasedpresence of such cations can cause the clayminerals to form clusters and increase thepermeability of the clay. Therefore, beforeselecting a compacted clay liner material, it isimportant to develop a good understandingof the composition of the waste that will beplaced in the waste management unit. EPA’sMethod 9100, in publication SW-846, mea-sures the hydraulic conductivity of soil sam-ples before and after exposure to permeants.6

Locating and Testing MaterialAlthough the selection process for com-

pacted clay liner construction materials canvary from project to project, some commonmaterial selection steps include locating andtesting materials at a potential borrow orcommercial pit before construction, andobserving and testing material performancethroughout construction. First, investigate apotential borrow or commercial pit to deter-mine the volume of materials available. The

next step is to test a representative sample ofsoil to determine material properties such asplasticity characteristics, percent gravel, andpercent fines. To confirm the suitability of thematerials once construction begins, youshould consider requesting that representa-tive samples from the materials in the borrowor commercial pit be tested periodically afterwork has started.

Material selection steps will vary, depend-ing on the origin of the materials for the pro-ject. For example, if a commercial pit providesthe materials, locating an appropriate onsiteborrow pit is not necessary. In addition to thetests performed on the material, it is recom-mended that a qualified inspector make visualobservations throughout the constructionprocess to ensure that harmful materials, suchas stones or other large matter, are not presentin the liner material.


in the construction of a liner and

the operation of a unit?

You should develop test pads to demon-strate construction techniques and materialperformance on a small scale. During unit con-struction and operation, some additional fac-tors influencing the performance of the linerinclude: preprocessing, subgrade preparation,method of compaction, and protection againstdesiccation and cracking. Each of these steps,from preprocessing through protection againstdesiccation and cracking, should be repeatedfor each lift or layer of soil.

Test PadsPreparing a test pad for the compacted

clay liner helps verify that the materials andmethods proposed will yield a liner thatmeets the desired hydraulic conductivity. Atest pad also provides an opportunity to

7B-6


demonstrate the performance of alternativematerials or methods of construction. A testpad should be constructed with the soil linermaterials proposed for a particular project,using the same preprocessing procedures,compaction equipment, and constructionpractices proposed for the actual liner. Acomplete discussion of test pads (coveringdimensions, materials, and construction) canbe found in Chapter 2 of EPA’s 1993 techni-cal guidance document Quality Assurance andQuality Control for Waste Containment Facilities(U.S. EPA, 1993c). A discussion of commonlyused methods to measure in-situ hydraulicconductivity is also contained in that chapter.

PreprocessingAlthough some liner

materials can be readyfor use in constructionimmediately after theyare excavated, manymaterials will requiresome degree of prepro-cessing. Preprocessingmethods include: watercontent adjustment,removal of oversizedparticles, pulverizationof any clumps, homoge-nization of the soils, andintroduction of addi-tives, such as bentonite.

Water contentadjustment. For naturalsoils, the degree of satu-ration of the soil liner atthe time of compaction,known as molding watercontent, influences theengineering properties ofthe compacted material.Soils compacted at watercontents less than opti-

mum tend to have a relatively high hydraulicconductivity. Soils compacted at water con-tents greater than optimum tend to have lowhydraulic conductivity and low strength.

Proper soil water content revolves aroundachieving a minimum dry density, which isexpressed as a percentage of the soil’s maxi-mum dry density. The minimum dry densitytypically falls in the range of 90 to 95 percentof the soil’s maximum dry density value. Fromthe minimum dry density range, the requiredwater content range can be calculated, asshown in Figure 1. In this example the soilhas a maximum dry density of 115 lb/cu ft.Based upon a required minimum dry densityvalue of 90 percent of maximum dry density,

Figure 1.

Water Content for Achieving a Specific Density



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which is equal to 103.5 lb/cu ft, the requiredwater content ranges from 10 to 28 percent.

It is less problematic to compact clay soilat the lower end of the required water con-tent range because it is easier to add water tothe clay soil than to remove it. Thus, if pre-cipitation occurs during construction of a sitewhich is being placed at the lower end of therequired water content range, the additionalwater might not result in a soil water contentgreater than the required range. Conversely, ifthe site is being placed at the upper end ofthe range, for example at 25 percent, anyadditional moisture will be excessive, result-ing in water content over 28 percent andmaking the 90 percent maximum dry densityunattainable. Under such conditions con-struction should halt while the soil is aeratedand excess moisture is allowed to evaporate.

Removal of oversized particles.Preprocessing clay materials, to remove cob-bles or large stones that exceed the maximumallowable particle size, can improve the soil’scompactibility and protect any adjacentgeomembrane from puncture. Particle sizeshould be small (e.g., 3/4 inch in diameter)for compaction purposes. If a geomembranewill be placed over the compacted clay, onlythe upper lift of clay needs to address con-cerns regarding puncture resistance.Observation by quality assurance and qualitycontrol personnel is the most effectivemethod to identify areas where oversized par-ticles need to be removed. Cobbles andstones are not the only materials that caninterfere with compactive efforts. Chunks ofdry, hard clay, also known as clods, oftenneed to be broken into smaller pieces to beproperly hydrated, remolded, and compact-ed. In wet clay, clods are less of a concernsince wet clods can often be remolded with areasonable compactive effort.

Soil amendments. If the soils at a unit donot have a sufficient percentage of clay, a com-

mon practice is to blend bentonite with themto reduce the hydraulic conductivity. Bentoniteis a clay mineral that expands when it comesinto contact with water. Relatively smallamounts of bentonite, on the order of 5 to 10percent, can be added to sand or other nonco-hesive soils to increase the cohesion of thematerial and reduce hydraulic conductivity.

Sodium bentonite is a common additiveused to amend soils. However, this additive isvulnerable to degradation as a result of con-tact with certain chemicals and wasteleachates. Calcium bentonite, a more perme-able material than sodium bentonite, is anoth-er common additive used to amend soils.Approximately twice as much calcium ben-tonite is needed to achieve a hydraulic con-ductivity comparable to that of sodiumbentonite. Amended soil mixtures generallyrequire mixing in a pug mill, cement mixer, orother mixing equipment that allows water tobe added during the mixing process.Throughout the mixing and placementprocesses, water content, bentonite content,and particle distribution should be controlled.Other materials that can be used as soil addi-tives include lime cement and other clay min-erals, such as atapulgite. It can be difficult tomix additives thoroughly with cohesive soils,or clays; the resultant mixture might notachieve the desired level of hydraulic conduc-tivity throughout the entire liner.

Subgrade PreparationIt is important to ensure that the subgrade

on which a compacted clay liner will be con-structed is properly prepared. When a com-pacted clay liner is the lowest component of aliner system, the subgrade consists of nativesoil or rock. Subgrade preparation for thesesystems involves compacting the native soilto remove any soft spots and adding water toor removing water from the native soil toobtain a specified firmness. Alternatively, in

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some cases, the compacted clay liner can beplaced on top of a geosynthetic material, suchas a geotextile. In such cases, subgrade prepa-ration involves ensuring the smoothness ofthe geosynthetic on which the clay liner willbe placed and the conformity of the geosyn-thetic material to the underlying material.

CompactionThe main purpose of compaction is to

densify the clay materials by breaking andremolding clods of material into a uniformmass. Since amended soils usually do notdevelop clumps, the primary objective ofcompaction for such materials is to increasethe material’s density. Proper compaction ofliner materials is essential to ensure that acompacted clay liner meets specifiedhydraulic conductivity standards. Factorsinfluencing the effectiveness of compactionefforts include: the type of equipment select-ed, the number of passes made over thematerials by such equipment, the lift thick-

ness, and the bonding between the lifts.Molding water content, described earlierunder preprocessing, is another factor influ-encing the effectiveness of compaction.

Type of equipment. Factors to considerwhen selecting compaction equipmentinclude: the type and weight of the com-pactor, the characteristics of any feet on thedrum, and the weight of the roller per unitlength of drummed surface. Heavy com-pactors, weighing more than 50,000 pounds,with feet long enough to penetrate a loose liftof soil, are often the best types of compactorfor clay liners. For bentonite-soil mixtures, afooted roller might not be appropriate. Forthese mixtures, where densification of thematerial is more important than kneading orremolding it to meet low hydraulic conduc-tivity specifications, a smooth-drum roller ora rubber- tired roller might produce betterresults. Figure 2 depicts two types of footedrollers, a fully penetrating footed roller and apartially-penetrating footed roller.

Source: U.S. EPA, 1993c.

Figure 2 Two Types of Footed Rollers


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For placement of liners on side slopes,consider the angle and length of the slope.Placing continuous lifts on a graduallyinclined slope will provide better continuitybetween the bottom and sidewalls of theliner. Since continuous lifts might be impossi-ble to construct on steeper slopes due to thedifficulties of operating heavy compactionequipment on these slopes, materials mightneed to be placed and compacted in horizon-tal lifts. When sidewalls are compacted hori-zontally, it is important to avoid creatingseepage planes, by securely connecting theedges of the horizontal lift with the bottom ofthe liner. Because the lift needs to be wideenough to accommodate compaction equip-ment, the thickness of the horizontal lift isoften greater than the thickness specified inthe design. In such cases, you should consid-er trimming soil material from the construct-ed side slopes and sealing the trimmedsurface using a sealed drum roller.

It is common for contractors to use severaldifferent types of compaction equipment dur-ing liner construction. Initial lifts might needthe use of a footed roller to fully penetrate aloose lift. Final lifts also might need the useof a footed roller for compaction, however,they might be formed better by using asmooth roller after the lift has been compact-ed to smooth the surface of the lift in prepa-ration for placement of an overlyinggeomembrane.

Number of passes. The number of passesmade by a compactor over clay materials caninfluence the overall hydraulic conductivityof the liner. The minimum number of passesthat is reasonable depends on a variety ofsite-specific factors and cannot be general-ized. In some cases, where a minimum cover-age is specified, it might be possible tocalculate the minimum number of passes tomeet such a specification. At least 5 to 15passes with a compactor over a given point

are usually necessary to remold and compactclay liner materials thoroughly.

An equipment pass can be defined as onepass of the compaction equipment or as onepass of a drum over a given area of soil. It isimportant to clearly define what is meant bya pass in any quality assurance or qualitycontrol plans. It does not matter which defin-ition is agreed upon, as long as the definitionis used consistently throughout the project.

Lift thickness. You should determine theappropriate thickness (as measured beforecompaction) of each of the several lifts thatwill make up the clay liner. The initial thick-ness of a loose lift will affect the compactiveeffort needed to reach the lower portions ofthe lift. Thinner lifts allow compactive effortsto reach the bottom of a lift and providegreater assurance that compaction will be suf-ficient to allow homogenous bondingbetween subsequent lifts. Loose lift thickness-es typically range between 13 and 25 cm (5and 10 in.). Factors influencing lift thicknessare: soil characteristics, compaction equip-ment, firmness of the foundation materials,and the anticipated compaction necessary tomeet hydraulic conductivity requirements.

Bonding between lifts. Since it isinevitable that some zones of higher andlower hydraulic conductivity, also known aspreferential pathways, will be present withineach lift, lifts should be joined or bonded in away that minimizes extending these zones orpathways between lifts. If good bonding isachieved, the preferential pathways will betruncated by the bonded zone between thelifts. At least two recommended methodsexist for preparing proper bonds. The firstmethod involves kneading, or blending thenew lift with the previously compacted liftusing a footed roller. Using a roller with feetlong enough to fully penetrate through thetop lift and knead the previous lift improvesthe quality of the bond. A second method

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involves using a disc harrow or similar equip-ment to scarify, or roughen, and wet the topinch of the recently placed lift, prior to plac-ing the next lift.

Protection Against Desiccation andCracking

You should consider how to protect com-pacted clay liners against desiccation andfreezing during and after construction.Protection against desiccation is important,because clay soil shrinks as it dries. Depend-ing on the extent of shrinkage, it can crack.Deep cracks, extending through more thanone lift, can cause problems. You shouldmeasure water content to determine whetherdesiccation is occurring.

There are several ways to protect compact-ed clay liners from desiccation. One preven-tive measure is to smooth roll the surface witha steel drummed roller to produce a thin,dense skin of soil; this layer can help mini-mize the movement of water into or out of thecompacted material. Another option is to wetthe clay periodically in a uniform manner;however, it is important to make sure to avoidcreating areas of excessive wetness. A thirdmeasure involves covering compacted clayliner materials with a sheet of white or clearplastic or tarp to help prevent against desicca-tion and cracking. The cover should beweighted down with sandbags or other mater-ial to minimize exposure of the underlyingmaterials to air. Using a light-colored plasticwill help prevent overheating, which can dryout the clay materials. If the clay liner is notbeing covered with a geosynthetic, anothermethod to prevent desiccation involves cover-ing the clay with a layer of protective coversoil or intentionally overbuilding the clay linerand shaving it down to liner grade.

Protection against freezing is anotherimportant consideration, because freezing can

increase the hydraulic conductivity of a liner.It is important to avoid construction duringfreezing weather. If freezing does occur andthe damage affects only a shallow depth, theliner can be repaired by rerolling the surface.If deeper freezing occurs, the repairs mightbe more complicated. For a general guide tofrost depths, see Figure 1 of Chapter 11—Performing Closure and Post-Closure Care.

B. Geomembranes orFlexible Membrane Liners

Geomembranes or flexible membrane lin-ers are used to contain or prevent waste con-stituents and leachate from escaping a wastemanagement unit. Geomembranes are madeby combining one or more plastic polymerswith ingredients such as carbon black, pig-ments, fillers, plasticizers, processing aids,crosslinking chemicals, anti-degradants, andbiocides. A wide range of plastic resins areused for geomembranes, including high den-sity polyethylene (HDPE), linear low densitypolyethylene (LLDPE), low density linearpolyethlene (LDLPE), very low density poly-ethlene (VLDPE), polyvinyl chloride (PVC),flexible polypropylene (fPP), chlorosulfonatedpolyethylene (CSPE or Hypalon), and ethyl-ene propylene diene termonomer (EPDM).Most manufacturers produce geomembranesthrough extrusion or calendering. In theextrusion process, a molten polymer isstretched into a nonreinforced sheet; extrud-ed geomembranes are usually made of HDPEand LLDPE. During the calendering process,a heated polymeric compound is passedthrough a series of rollers. In this process, ageomembrane can be reinforced with awoven fabric or fibers. Calendered geomem-branes are usually made of PVC and CSPE.

What are the thickness recommen-

dations for geomembrane liners?

Geomembranes range in thicknesses from 20to 120 mil (1 mil = 0.001 in.). A good designshould include a minimum thickness of 30 mil,except for HDPE liners, which should have aminimum thickness of 60 mil. These recom-mended minimum thicknesses ensure that theliner material will withstand the stress of con-struction and the weight load of the waste, andallow adequate seaming to bind separategeomembrane panels. Reducing the potentialfor tearing or puncture, through proper con-struction and quality control, is essential for ageomembrane to perform effectively.


in the design of a geomembrane

liner?

Several factors to address in the designinclude: determining appropriate materialproperties and testing to ensure these proper-ties are met, understanding how the liner willinteract with the intended waste stream,accounting for all stresses imposed by thedesign, and ensuring adequate friction.

Material Properties and Selection When designing a geomembrane liner, you

should examine several properties of thegeomembrane material in addition to thick-ness, including: tensile behavior, tear resis-tance, puncture resistance, susceptibility toenvironmental stress cracks, ultraviolet resis-tance, and carbon black content.

Tensile behavior. Tensile behavior refers tothe tensile strength of a material and its abilityto elongate under strain. Tensile strength is theability of a material to resist pulling stresseswithout tearing. The tensile properties of ageomembrane must be sufficient to satisfy thestresses anticipated during its service life.

These stresses include the self-weight of thegeomembrane and any down drag caused bywaste settlement on side slope liners.

Puncture and tear resistance.Geomembrane liners can be subject to tearingduring installation due to high winds or han-dling. Puncture resistance is also important toconsider since geomembranes are oftenplaced above or below materials that mighthave jagged or angular edges. For example,geomembranes might be installed above agranular drainage system that includes gravel.

Susceptibility to environmental stresscracks. Environmental factors can causecracks or failures before a liner is stressed toits manufactured strength. These imperfec-tions, referred to as environmental stresscracks, often occur in areas where a liner hasbeen scratched or stressed by fatigue. Thesecracks can also result in areas where excesssurface wetting agents have been applied. Insurface impoundments, where the geomem-brane liner has greater exposure to the atmos-phere and temperature changes, suchexposure can increase the potential for envi-ronmental stress cracking.

Ultraviolet resistance. Ultraviolet resis-tance is another factor to consider in thedesign of geomembrane liners, especially incases where the liner might be exposed toultraviolet radiation for prolonged periods oftime. In such cases, which often occur in sur-face impoundments, ultraviolet radiation cancause degradation and cracking in thegeomembrane. Adding carbon black or otheradditives during the manufacturing processcan increase a geomembrane’s ultravioletresistance. Backfilling over the exposedgeomembrane also works to prevent degrada-tion due to ultraviolet radiation.

Interactions With WasteSince the main purpose of a geomembrane

is to provide a barrier and prevent contami-


7B-11

nants from penetrating through the geomem-brane, chemical resistance is a critical consid-eration. Testing for chemical resistance mightbe warranted depending on the type, vol-umes, and characteristics of waste managedat a particular unit and the type of geomem-brane to be used. An established method fortesting the chemical resistance of geomem-branes, EPA Method 9090, can be found inSW-846. ASTM has also adopted standardsfor testing the chemical compatibility of vari-ous geosynthetics, including geomembranes,with leachates from waste management units.ASTM D-5747 provides a standard for testingthe chemical compatibility ofgeomembranes.7

Stresses Imposed by Liner DesignA liner design should take into account the

stresses imposed on the liner by the designconfiguration. These stresses include: the dif-ferential settlement in foundation soil, strainrequirements at the anchor trench, strainrequirements over long, steep side slopes,stresses resulting from compaction, and seis-mic stresses. Often an anchor trench designedto secure the geomembrane during construc-tion is prepared along the perimeter of a unitcell. This action can help prevent thegeomembrane from slipping down the interi-or side slopes. Trench designs should includea depth of burial sufficient to hold the speci-fied length of liner. If forces larger than thetensile strength of the liner are inadvertentlydeveloped, then the liner could tear. For thisreason, the geomembrane liner should beallowed to slip or give in the trench after con-struction to prevent such tearing. To helpreduce unnecessary stresses in the liner de-sign, it is advisable to avoid using horizontalseams. For more information on design stress-es, consult Geosynthetic Guidance forHazardous Waste Landfill Cells and SurfaceImpoundments (U.S. EPA, 1987).

Designing for Adequate FrictionAdequate friction between the geomem-

brane liner and the soil subgrade, as well asbetween any geosynthetic components, isnecessary to prevent extensive slippage orsloughing on the slopes of a unit. Designequations for such components should evalu-ate: 1) the ability of a liner to support its ownweight on side slopes, 2) the ability of a linerto withstand down-dragging during and afterwaste placement, 3) the best anchorage con-figuration for the liner, 4) the stability of soilcover on top of a liner, and 5) the stability ofother geosynthetic components, such as geot-extiles or geonets, on top of a liner. An evalu-ation of these issues can affect the choice ofgeomembrane material, polymer type, fabricreinforcement, thickness, and texture neces-sary to achieve the design requirements.Interface strengths can be significantlyimproved by using textured geomembranes.

What issues should be consid-

ered in the construction of a

geomembrane liner?

When preparing to construct a geomem-brane liner, you should plan appropriateshipment and handling procedures, performtesting prior to construction, prepare thesubgrade, consider temperature effects, andaccount for wind effects. In addition, youshould select a seaming process, determine amaterial for and method of backfilling, andplan for testing during construction.

Shipment, Handling, and Site Storage You should follow quality assurance and

quality control procedures to ensure properhandling of geomembranes. Different types ofgeomembrane liners require different types ofpackaging for shipment and storage.Typically a geomembrane manufacturer willprovide specific instructions outlining the

7B-12

7 ASTM D-5747, Practice for Tests to Evaluate the Chemical Resistance of Geomembranes to Liquids.


handling, storage, and construction specifica-tions for a product. In general, HDPE andLLDPE geomembrane liners are packaged in aroll form, while PVC and CSPE-R liners(CSPE-R refers to a CSPE geomembrane linerreinforced with a fabric layer) are packaged inpanels, accordion-folded in two directions,and placed onto pallets. Whether the liner isshipped in rolls or panels, you should pro-vide for proper storage. The rolls and panelsshould be packaged so that fork lifts or otherequipment can safely transport them. Forrolls, this involves preparing the roll to have asufficient inside diameter so that a fork liftwith a long rod, known as a stinger, can beused for lifting and moving. For accordionpanels, proper packaging involves using astructurally-sound pallet, wrapping panels intreated cardboard or plastic wrapping to pro-tect against ultraviolet exposure, and usingbanding straps with appropriate cushioning.Once the liners have been transported to thesite, the rolls or panels can be stored until thesubgrade or subbase (either natural soils oranother geosynthetic) is prepared.

Subgrade Preparation Before a geomembrane liner is installed,

you should prepare the subgrade or subbase.The subgrade material should meet specifiedgrading, moisture content, and densityrequirements. In the case of a soil subgrade,it is important to prevent construction equip-ment used to place the liner from deformingthe underlying materials. If the underlyingmaterials are geosynthetics, such as geonetsor geotextiles, you should remove all foldsand wrinkles before the liner is placed. Forfurther information on geomembrane place-ment, see Chapter 3 of EPA’s Technical

Guidance Document: Quality Assurance andQuality Control for Waste Containment Facilities(U.S. EPA, 1993c).

Testing Prior to Construction Before any construction begins, is it recom-

mended that you test both the geomembranematerials from the manufacturer and theinstallation procedures. Acceptance and con-formance testing is used to evaluate the per-formance of the manufactured geomembranes.Constructing test strips can help evaluate howwell the intended construction process andquality control procedures will work.

Acceptance and conformance testing.You should perform acceptance and confor-mance testing on the geomembrane linerreceived from the manufacturer to determinewhether the materials meet the specificationsrequested. While the specific ASTM testmethods vary depending on geomembranetype, recommended acceptance and confor-mance testing for geomembranes includesevaluations of thickness, tensile strength andelongation, and puncture and tear resistancetesting, as appropriate. For most geomem-brane liner types, the recommended ASTMmethod for testing thickness is ASTM D-5199.8 For measuring the thickness of tex-tured geomembranes, you should use ASTMD-5994.9 For tensile strength and elongation,ASTM D-638 is recommended for the HDPEand LLDPE sheets, while ASTM D-882 andASTM D-751 are recommended for PVC andCSPE geomembranes, respectively.10 Punctureresistance testing is typically recommendedfor HDPE and LLDPE geomembranes usingASTM D-4833.11 To evaluate tear resistancefor HDPE, LLDPE, and PVC geomembrane


7B-13

8 ASTM D-5199, Standard Test Method for Measuring Nominal Thickness of Geotextiles andGeomembranes.

9 ASTM D-5994, Measuring Core Thickness of Textured Geomembranes.

10 ASTM D-638, Standard Test Method for Tensile Properties of Plastics.ASTM D-882, Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.ASTM D-751, Standard Test Methods for Coated Fabrics.

11 ASTM D-4833, Standard Test Method for Index Puncture Resistance of Geotextiles, Geomembranes,and Related Products.

liners, the recommended testing method isASTM D-1004, Die C.12 For CSPE-Rgeomembranes, ply adhesion is more of aconcern than tear or puncture resistance andcan be evaluated using ASTM D-413,Machine Method, Type A.13

Test strips. In preparation for liner place-ment and field seaming, you should developtest strips and trial seams as part of the con-struction process. Construction of such sam-ples should be performed in a manner thatreproduces all aspects of field production.Providing an opportunity to test seamingmethods and workmanship helps ensure thatthe quality of the seams remains constantand meets specifications throughout theentire seaming process.

Temperature Effects Liner material properties can be altered by

extreme temperatures. High temperatures cancause geomembrane liner surfaces to sticktogether, a process commonly referred to asblocking. On the other hand, low tempera-ture can cause the liner to crack whenunrolled or unfolded. Recommended maxi-mum and minimum allowable sheet tempera-tures for unrolling or unfolding geomembraneliners are 50°C (122°F) and 0°C (32°F),respectively. In addition to sticking and crack-ing, extreme temperatures can cause geomem-branes to contract or expand. Polyethylenegeomembranes expand when heated and con-tract when cooled. Other geomembranes cancontract slightly when heated. Those respon-sible for placing the liner should take temper-ature effects into account as they place, seam,and backfill in the field.

Wind EffectsIt is recommended that you take measures

to protect geomembrane liners from winddamage. Windy conditions can increase the

potential for tearing as a result of uplift. Ifwind uplift is a potential problem, panels canbe weighted down with sand bags.

Seaming ProcessesOnce panels or rolls have been placed,

another critical step involves field-seamingthe separate panels or rolls together. Theselected seaming process, such as thermal orchemical seaming, will depend on the chemi-cal composition of the liner. To ensure theintegrity of the seam, you should use theseaming method recommended by the manu-facturer. Thermal seaming uses heat to bondtogether the geomembrane panels. Examplesof thermal seaming processes include extru-sion welding and thermal fusion (or meltbonding). Chemical seaming involves the useof solvents, cement, or an adhesive. Chemicalseaming processes include chemical fusionand adhesive seaming. For more informationon seaming methods, Technical GuidanceDocument: Inspection Techniques for theFabrication of Geomembrane Field Seams (U.S.EPA, 1991c), contains a full chapter on eachof the traditional seaming methods and addi-tional discussion of emerging techniques,such as ultrasonic, electrical conduction, andmagnetic energy source methods.

Consistent quality in fabricating fieldseams is paramount to liner performance.Conditions that could affect seaming shouldbe monitored and controlled during installa-tion. Factors influencing seam constructionand performance include: ambient tempera-ture, relative humidity, wind uplift, changesin geomembrane temperature, subsurfacewater content, type of supporting surfaceused, skill of the seaming crew, quality andconsistency of chemical or welding materials,preparation of liner surfaces to be joined,moisture at the seam interface, and cleanli-ness of the seam interface.

7B-14

12 ASTM D-1004, Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting.

13 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.


To help control some of these factors, nomore than the amount of sheeting that can beused during a shift or a work day should bedeployed at one time. To prevent erosion ofthe underlying soil surface or washout of thegeomembrane, proper storm water controlmeasures should be employed. Ambient tem-perature can become a concern, if thegeomembrane liner has a high percentage ofcarbon black. Although the carbon black willhelp to prevent damage resulting from ultra-violet radiation, because its dark colorabsorbs heat, it can increase the ambient tem-perature of the geomembrane, making instal-lation more complicated. To avoid surfacemoisture or high subsurface water content,geomembranes should not be deployed whenthe subgrade is wet.

Regardless of how well a geomembraneliner is designed, its ability to meet perfor-mance standards depends on proper qualityassurance and quality control during installa-tion. Geomembrane sheets and seams aresubject to tearing and puncture during instal-lation; punctures or tears can result from con-tact with jagged edges or underlying materialsor by applying stresses greater than thegeomembrane sheet can handle. Proper quali-ty assurance and quality control can helpminimize the occurrence of pinhole or seamleaks. For example, properly preparing theunderlying layer and ensuring that the gravelis of an acceptable size reduces the potentialfor punctures.

Protection and BackfillingGeomembrane liners that can be damaged

by exposure to weather or work activitiesshould be covered with a layer of soil or ageosynthetic as soon as possible after qualityassurance activities associated with geomem-brane testing are completed. If the backfilllayer is a soil material, it will typically be adrainage material like sand or gravel. If the

cover layer is a geosynthetic, it will typicallybe a geonet or geocomposite drain placeddirectly over the geomembrane. Carefulplacement of backfill materials is critical toavoid puncturing or tearing the geomem-brane material.

For soil covers, three considerations deter-mine the amount of slack to be placed in theunderlying geomembrane. These considera-tions include selecting the appropriate type ofsoil, using the proper type of equipment, andestablishing a placement procedure for thesoil. When selecting a soil for backfilling,characteristics to consider include particlesize, hardness, and angularity, as each of thesecan affect the potential for tearing or punctur-ing the liner. To prevent wrinkling, soil coversshould be placed over the geomembrane insuch a way that construction vehicles do notdrive directly on the liner. Care should betaken not to push heavy loads of soil over thegeomembrane in a continuous manner.Forward pushing can cause localized wrinklesto develop and overturn in the direction ofmovement. Overturned wrinkles create sharpcreases and localized stress in the liner andcan lead to premature failure. A recommend-ed method for placing soil involves continual-ly placing small amounts of soil or drainagematerial and working outward over the toe ofthe previously placed material.

Another recommended method involvesplacing soil over the liner with a large back-hoe and spreading it with a bulldozer or sim-ilar equipment. If a predetermined amount ofslack is to be placed in the geomembrane, thetemperature of the liner becomes an impor-tant factor, as it will effect the ability of theliner to contract and expand. Although therecommended methods for coveringgeomembrane liners with soil can take moretime than backfilling with larger amounts ofsoil, these methods are designed to preventdamage caused by covering the liner with too


7B-15

much soil too quickly. In the long run, pre-venting premature liner failure can be fasterand more cost-effective than having to repaira damaged liner.

The types of geosynthetics that are oftenused as protective covering include geotex-tiles and geonets. Geogrids and drainage geo-composites can be used for cover soilreinforcement on slopes. The appendix at theend of this chapter provides additional infor-mation on geosynthetic materials. Forgeosynthetic protective covers, as with soilbackfilling, to prevent tearing or puncturing,most construction vehicles should not bepermitted to move directly on the geomem-brane. Some possible exceptions includesmall, 4-wheel, all terrain vehicles or othertypes of low ground pressure equipment.Even with these types of vehicles, driversshould take extreme care to avoid move-ments, such as sudden starts, stops, andturns, which can damage the geomembrane.Seaming-related equipment should beallowed on the geomembrane liner, as long asit does not damage the liner. Geosyntheticmaterials are placed directly on the liner andare not bonded to it.

Testing During ConstructionTesting during construction enables assess-

ment of the integrity of the seams connectingthe geomembrane panels. Tests performed onthe geomembrane seams are categorized aseither destructive or nondestructive.

Destructive testing. Destructive testingrefers to removing a sample from the linerseam or sheet and performing tests on thesample. For liner seams, destructive testingincludes shear testing and peel testing; forliner sheets, it involves tensile testing. Whilequality control procedures often requiredestructive testing prior to construction, inorder to ensure that the installed seams andsheets meet performance standards, destruc-

tive testing should be performed during con-struction also. For increased quality assur-ance, it is recommended that peel and sheartests on samples from the installed geomem-brane be performed by an independent labo-ratory. Testing methods for shear testing, peeltesting, and tensile testing vary for differentgeomembrane liner types.

Determining the number of samples totake is a difficult step. Taking too few sam-ples results in a poor statistical representationof the geomembrane quality. On the otherhand, taking too many samples requiresadditional costs and increases the potentialfor defects. Defects can result from the repairpatches used to cover the areas from whichsamples were taken.

A common sampling strategy is “fixedincrement sampling” where samples aretaken at a fixed increment along the length ofthe geomembrane. Increments range from 80to 300 m (250 to 1,000 ft). The type ofwelding, such as extrusion or fusion welding,used to connect the seams and the type ofgeomembrane liner can also help determinethe appropriate sampling interval. For exam-ple, extrusion seams on HDPE require grind-ing prior to welding and if extensive grindingoccurs, the strength of the HDPE mightdecrease. In such cases, sampling at closerintervals, such as 90 to 120 m (300 to 400ft), might provide a more accurate descrip-tion of material properties. If the seam is adual hot edge seam, both the inner and outerseams might need to be sampled and tested.

If test results for the seam or sheet samplesdo not meet the acceptance criteria for thedestructive tests, you should continue testingthe area surrounding the rejected sample todetermine the limits of the low quality seam.Once the area of low quality has been identi-fied, then corrective measures, such as seaminga cap over the length of the seam or reseamingthe affected area, might be necessary.

7B-16


Nondestructive testing. Unlike destruc-tive tests, which examine samples taken fromthe geomembrane liner in the containmentarea, nondestructive tests are designed toevaluate the integrity of larger portions ofgeomembrane seams without removing piecesof the geomembrane for testing. Commonnondestructive testing methods include: theprobe test, air lance, vacuum box, ultrasonicmethods (pulse echo, shadow, and impedanceplanes), electrical spark test, pressurized dualseam, and electrical resistivity. You shouldselect the test method most appropriate forthe material and seaming method. If sectionsof a seam fail to meet the acceptable criteriaof the appropriate nondestructive test, thenthose sections need to be delineated andpatched, reseamed, or retested. If repairingsuch sections results in large patches or areasof reseaming, then destructive test methodsare recommended to verify the integrity ofsuch pieces.

C. Geosynthetic Clay LinersIf a risk evaluation recommended the use

of a single liner, another option to consider isa geosynthetic clay liner (GCL). GCLs are fac-tory-manufactured, hydraulic barriers typical-ly consisting of bentonite clay (or other verylow permeability materials), supported bygeotextiles or geomembranes held together byneedling, stitching, or chemical adhesives.GCLs can be used to augment or replacecompacted clay liners or geomembranes, orthey can be used in a composite manner toaugment the more traditional compacted clayor geomembrane materials. GCLs are typical-ly used in areas where clay is not readilyavailable or where conserving air space is animportant factor. As GCLs do not have thelevel of long-term field performance data thatgeomembranes or compacted clay liners do,states might request a demonstration thatperformance of the GCL design will be com-

parable to that of compacted clay orgeomembrane liners.

What are the mass per unit area

and hydraulic conductivity recom-

mendations for geosynthetic clay

liners?

Geosynthetic clay liners are often designedto perform the same function as compactedclay and geomembrane liner components. Forgeosynthetic clay liners, you should designfor a minimum of 3.7 kg/m2 (0.75 lb/ft2) dryweight (oven dried at 105°C) of bentoniteclay with a hydrated hydraulic conductivityof no more than 5 x 10-9 cm/sec (2 x 10-9

in/sec). It is important to follow manufacturerspecifications for proper GCL installation.


ered in the design of a geosyn-

thetic clay liner?

Factors to consider in GCL design are thespecific material properties needed for theliner and the chemical interaction or compat-ibility of the waste with the GCL. When con-sidering material properties, it is important tokeep in mind that bentonite has a low shearstrength when it is hydrated. Manufacturershave developed products designed to increaseshear strength.

Materials Selection and PropertiesFor an effective GCL design, material

properties should be clearly defined in thespecifications used during both manufactureand construction. The properties that shouldbe specified include: type of bonds, thick-ness, moisture content, mass per unit area,shear strength, and tensile strength. Each ofthese properties is described below.


7B-17

Type of bonds. Geosynthetic clay linersare available with a variety of bondingdesigns, which include a combination of clay,adhesives, and geomembranes or geotextiles.The type of adhesives, geotextiles, andgeomembranes used as components of GCLsvaries widely. One type of available GCLdesign uses a bentonite clay mixed with anadhesive bound on each side by geotextiles.A variation on this design involves stitchingthe upper and lower geotextiles togetherthrough the clay layer. Alternatively, anotheroption is to use a GCL where geotextiles oneach side of adhesive or nonadhesive ben-tonite clay are connected by needle punch-ing. A fourth variation uses a clay mixed withan adhesive bound to a geomembrane on oneside; the geomembrane can be either thelower or the upper surface. Figure 3 displayscross section sketches of the four variationsof GCL bonds. While these options describeGCLs available at the time of this Guide,emerging technologies in GCL designsshould also be reviewed and considered.

Thickness. The thickness of the variousavailable GCL products ranges from 4 to 6mm (160 to 320 mil). Thickness measure-ments are product dependent. Some GCLscan be quality controlled for thickness whileothers cannot.

Moisture content. GCLs are delivered tothe job site at moisture contents ranging from5 to 23 percent, referred to as the “dry” state.GCLs are delivered dry to prevent prematurehydration, which can cause unwanted varia-tions in the thickness of the clay componentas a result of uneven swelling.

Stability and shear strength. GCLsshould be manufactured and selected to meetthe shear strength requirements specified indesign plans. In this context, shear strengthis the ability of two layers to resist forcesmoving them in opposite directions. Sincehydrated bentonite clay has low shear

strength, bentonite clay can be placedbetween geotextiles and stitch bonded orneedle- punched to provide additional stabil-ity. For example, a GCL with geotextiles sup-ported by stitch bonding has greater internalresistance to shear in the clay layer than aGCL without any stitching. Needle-punchedGCLs tend to provide greater resistance thanstitch-bonded GCLs and can also provideincreased friction resistance against anadjoining layer, because they require the useof nonwoven geotextiles. Increased friction isan important consideration on side slopes.

Mass per unit area. Mass per unit arearefers to the bentonite content of a GCL. It isimportant to distribute bentonite evenlythroughout the GCL in order to meet desiredhydraulic conductivity specifications. AllGCL products available in North America usea sodium bentonite clay with a mass per unitarea ranging from 3.2 to 6.0 kg/m2 (0.66 to1.2 lb/ft2), as manufactured.

Interaction With WasteDuring the selection process for a GCL

liner, you should evaluate the chemical com-patibility of the liner materials with the typesof waste that are expected to be placed in theunit. Certain chemicals, such as calcium, canhave an adverse effect on GCLs, resulting in aloss of liner integrity. Specific information onGCL compatibilities should be available fromthe manufacturer.



geosynthetic clay liner?

Prior to and during construction, it is rec-ommended that a qualified professionalshould prepare construction specifications forthe GCL. In these specifications, proceduresfor shipping and storing materials, as well asperforming acceptance testing on delivered

7B-18



7B-19

Figure 3

Four Variations of GCL Bonding Methods

Source: U.S. EPA, 1993c.

materials, should be identified. The specifica-tions should also address methods for sub-grade preparation, joining panels, repairingsections, and protective backfilling.

Shipment, Handling, and SiteStorage

GCLs are manufactured in widths ofapproximately 2 to 5 m (7 to 17 ft) andlengths of 30 to 60 m (100 to 200 ft).Directly after manufacturing, GCLs are rolledaround a core and covered with a thin plasticprotective covering. This waterproof coveringserves to protect the material from prematurehydration. GCLs should be stored at the fac-tory with these protective coverings. Typicalstorage lengths range from a few days to 6months. To ensure protection of the plasticcovering and the rolls themselves duringloading and unloading, it is recommendedthat qualified professionals specify the equip-ment needed at the site to lift and deploy therolls properly.

To reduce the potential for accidentaldamage or for GCLs to absorb moisture atthe site, you should try to arrange for “just-in-time-delivery” for GCLs transported fromthe factory to the field. Even with “just-in-time-delivery,” it might be necessary to storeGCLs for short periods of time at the site.Often the rolls can be delivered in trailers,which can then serve as temporary storage.To help protect the GCLs prior to deploy-ment, you should use wooden pallets to keepthe rolls off the ground, placing heavy, water-proof tarps over the GCL rolls to protectthem from precipitation, and using sandbagsto help keep the tarps in place.

Manufacturer specifications should alsoindicate how high rolls of GCLs can bestacked horizontally during storage. Over-stacking can cause compression of the corearound which the GCL is wrapped. A dam-

aged core makes deployment more difficultand can lead to other problems. For example,rolls are sometimes handled by a fork liftwith a stinger attached. The stinger is a longtapered rod that fits inside the core. If thecore is crushed, the stinger can damage theliner during deployment.

Acceptance and ConformanceTesting

Acceptance and conformance testing is rec-ommended either upon delivery of the GCLrolls or at the manufacturer’s facility prior todelivery. Conformance test samples are usedto ensure that the GCL meets the projectplans and specifications. GCLs should berewrapped and replaced in dry storage areasimmediately after test samples are removed.Liner specifications should prescribe samplingfrequencies based on either total area or onnumber of rolls. Since variability in GCLs canexist between individual rolls, it is importantfor acceptance and conformance testing toaccount for this. Conformance testing caninclude the following.

Mass per unit area test. The purpose ofevaluating mass per unit area is to ensure aneven distribution of bentonite throughout theGCL panel. Although mass per unit areavaries from manufacturer to manufacturer, atypical minimum value for oven dry weightis 3.7 kg/m2 (0.75 lb/ft2). Mass per unit areashould be tested using ASTM D-5993.14 Thistest measures the mass of bentonite per unitarea of GCL. Sampling frequencies should bedetermined using ASTM D- 4354.15

Free swell test. Free swell refers to theability of the clay to absorb liquid. EitherASTM D-5890 or GRI-GCL1, a test methoddeveloped by the Geosynthetic ResearchInstitute, can be used to evaluate the freeswell of the material.16

7B-20

14 ASTM D-5993, Standard Test Method for Measuring Mass per Unit Area of Geosynthetic Clay Liners.

15 ASTM D-4354, Standard Practice for Sampling of Geosynthetics for Testing.

16 ASTM D-5890, Test Method for Swell Index of Clay Mineral Components of Geosynthetic Clay Liners.GRI-GCL1, Swell Measurement of the Clay Component of Geosynthetic Clay Liners.


Direct shear test. Shear strength of theGCLs can be evaluated using ASTM D-5321.17

The sampling frequency for this performance-oriented test is often based on area, such asone test per 10,000 m2 (100,000 ft2).

Hydraulic conductivity test. Either ASTMD-5084 (modified) or GRI-GCL2 will mea-sure the ease with which liquids can movethrough the GCL.18

Other tests. Testing of any geotextiles orgeomembranes should be made on the origi-nal rolls of the geotextiles or geomembranesand before they are fabricated into the GCLproduct. Once these materials have beenmade part of the GCL product, their proper-ties can change as a result of any needling,stitching, or gluing. Additionally, any peeltests performed on needle punched or stitchbonded GCLs should use the modified ASTMD-413 with a recommended sampling fre-quency of one test per 2,000 m2 (20,000 ft2).19

Subgrade PreparationBecause the GCL layer is relatively thin,

the first foot of soil underlying the GCLshould have a hydraulic conductivity of 1 x10-5 cm/sec or less. Proper subgrade prepara-tion is essential to prevent damage to theGCL layer as it is installed. This includesclearing away any roots or large particles thatcould potentially puncture the GCL and itsgeotextile or geomembrane components. Thesoil subgrade should be of the specified grad-ing, moisture content, and density requiredby the installer and approved by a construc-tion quality assurance engineer for placementof the GCL. Construction equipment deploy-ing the rolls should not deform or rut the soilsubgrade excessively. To help ensure this, thesoil subgrade should be smooth rolled with a

smooth-wheel roller and maintained in asmooth condition prior to deployment.

Joining PanelsGCLs are typically joined by overlapping

panels, without sewing or mechanically con-necting pieces together. To ensure properjoints, you should specify minimum andmaximum overlap distances. Typical overlapdistances range from 150 to 300 mm (6 to 12in.). For some GCLs, such as needle punchedGCLs with nonwoven geotextiles, it might benecessary to place bentonite on the area ofoverlap. If this is necessary, you should takesteps to prevent fugitive bentonite particlesfrom coming into contact with the leachatecollection system, as they can cause physicalclogging.

Repair of Sections Damaged DuringLiner Placement

During installation, GCLs might incursome damage to either the clay component orto any geotextiles or geomembranes. Fordamage to geotextile or geomembrane com-ponents, repairs include patching using geot-extile or geomembrane materials. If the claycomponent is disturbed, a patch made fromthe same GCL product should be used to per-form any repairs.

Protective BackfillingAs soon as possible after completion of

quality assurance and quality control activi-ties, you should cover GCLs with either a soillayer or a geosynthetic layer to preventhydration. The soil layer can be a compactedclay liner or a layer of coarse drainage materi-al. The geosynthetic layer is typically a


7B-21

17 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic orGeosynthetic and Geosynthetic Friction by the Direct Shear Method.

18 ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated PorousMaterials Using a Flexible Wall Permeameter.GRI-GCL2, Permeability of Geosynthetic Clay Liners (GCLs).

19 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.

geomembrane; however, depending on site-specific designs, it can be a geotextile. Asnoted earlier, premature hydration beforecovering can lead to uneven swelling, result-ing in a GCL with varied thickness.Therefore, a GCL should be covered with itssubsequent soil or geosynthetic layer before arainfall or snowfall occurs. Premature hydra-tion is less of a concern for GCLs, where thegeosynthetic components are needle punchedor stitch bonded, because these types of con-nections can better limit clay expansion.

III. CompositeLiners

A composite liner consists of both ageomembrane liner and natural soil. Thegeomembrane forms the upper componentwith the natural soil being the lower compo-nent. The ususal variations are:

• Geomembrane over compacted clayliner (GM/CCL).

• Geomembrane over geosynthetic clayliner (GM/GCL).

• Geomembrane over geosynthetic clayliner over compacted clay liner(GM/GCL/CCL).

A composite liner provides an effectivehydraulic barrier by combining the comple-mentary properties of the two different linersinto one system. The geomembrane provides ahighly impermeable layer to maximize leachatecollection and removal. The natural soil linerserves as a backup in the event of any leakagefrom the geomembrane. With a compositeliner design, you should construct a leachatecollection and removal system above thegeomembrane. Information on design and con-struction of leachate collection and removalsystems is provided in Section V below.


hydraulic conductivity recom-

mendations for composite liners?

Each component of the composite linershould follow the recommendations forgeomembranes, geosynthetic clay liners, andcompacted clay liners described earlier.Geomembrane liners should have a mini-mum thickness of 30 mil, except for HDPEliners, which should have a minimum thick-ness of 60 mil. Similarly, compacted clay lin-ers should be at least 2 feet thick and aretypically 2 to 5 feet thick. For compactedclay liners and geosynthetic clay liners, youshould use materials with maximumhydraulic conductivities of 1 x 10-7 cm/sec (4x 10-8 in/sec) and 5 x 10-9 cm/sec (2 x 10-9

in/sec), respectively.


ered in the design of a compos-

ite liner?

As a starting point, you should follow thedesign considerations discussed previously forsingle liners. In addition, to achieve the bene-fits of a combined liner system, you shouldinstall the geomembrane to ensure good con-tact with the compacted clay layer. The uni-formity of contact between the geomembraneand the compacted clay layer helps controlthe flow of leachate. Porous material, such asdrainage sand or a geonet, should not beplaced between the geomembrane and theclay layer. Porous materials will create a layerof higher hydraulic conductivity, which willincrease the amount of leakage below anygeomembrane imperfection.

You should consider the friction or shearstrength between a compacted clay layer anda geomembrane. The friction or shear stressat this surface is often low and can form aweak plane on which sliding can occur.

7B-22


ASTM D-5321 provides a test method fordetermining the friction coefficient of soil andgeomembranes.20 When using bentonite-amended soils, it is important to account forhow the percentage of bentonite added andthe degree of saturation affect interface fric-tion. To provide for stable slopes, it is impor-tant to control both the bentonite andmoisture contents. A textured geomembranecan increase the friction with the clay layerand improve stability.



composite liner?

To achieve good composite bonding, thegeomembrane and the compacted clay layershould have good hydraulic contact. Toimprove good contact, you should smooth-roll the surface of the compacted clay layerusing a smooth, steel-drummed roller andremove any stones. In addition, you shouldplace and backfill the geomembrane so as tominimize wrinkles.

The placement of geomembranes onto acompacted clay layer poses a challenge,because workers cannot drive heavymachines over the clay surface withoutpotentially damaging the compacted claycomponent. Even inappropriate footwear canleave imprints in the clay layer. It might bepossible to drive some types of low groundpressure equipment or small, 4-wheel, all ter-rain vehicles over the clay surface, but driversshould take extreme care to avoid move-ments, such as sudden starts, stops, andturns, that could damage the surface. Toavoid damaging the clay layer, it is recom-mended that you unroll geomembranes bylifting the rolls onto jacks at a cell side andpulling down on the geomembrane manually.Also, the entire roll with its core can beunrolled onto the cell (with auxiliary supportusing ropes on embankments).

To minimize desiccation of the compactedclay layer, you should place the geomem-brane over the clay layer as soon as possible.Additional cover materials should also beplaced over the geomembrane. Exposedgeomembranes absorb heat, and high temper-atures can dry out and crack an underlyingcompacted clay layer. Daily cyclic changes intemperature can draw water from the claylayer and cause this water to condense on theunderside of the geomembrane. This with-drawal of water can lead to desiccation crack-ing and potential interface stability concerns.

IV. Double Liners(Primary andSecondary LinedSystems)

In a double-lined waste management unit,there are two distinct liners—one primary(top) liner and one secondary (bottom) liner.Each liner might consist of compacted clay, ageomembrane, or a composite (consisting of ageomembrane and a compacted clay layer orGCL). Above the primary liner, it is recom-mended that you construct a leachate collec-tion and removal system to collect and conveyliquids out of the waste management unit andto control the depth of liquids above the pri-mary liner. In addition, you should place aleak detection, collection, and removal systembetween the primary and secondary liner.This leak detection system will provide leakwarning, as well as collect and remove anyliquid or leachate that has escaped the prima-ry liner. See section V below for informationon the design of leachate collection andremoval systems and leak detection, collec-tion, and removal systems.


7B-23

20 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic orGeosynthetic and Geosynthetic Friction by the Direct Shear Method.


hydraulic conductivity recom-

mendations for double liners?

Each component of the double linershould follow the recommendations forgeomembranes, compacted clay liners, orcomposite liners described earlier.Geomembrane liners should have a minimumthickness of 30 mil, except for HDPE liners,which should have a minimum thickness of60 mil. Similarly, compacted clay linersshould be at least 2 feet thick and are typical-ly 2 to 5 feet thick. For compacted clay linersand geosynthetic clay liners, use materialswith maximum hydraulic conductivities of 1x 10-7 cm/sec (4 x 10-8 in/sec) and 5 x 10-9

cm/sec (2 x 10-9 in/sec), respectively.


ered in the design and construc-

tion of a double liner?

Like composite liners, double liners arecomposed of a combination of single liners.When planning to design and construct adouble liner, you should consult the sectionson composite and single liners first. In addi-tion, you should consult the sections onleachate collection and removal systems andleak detection systems.

V. LeachateCollection andLeak DetectionSystems

One of the most important functions of awaste management unit is controllingleachate and preventing contamination of theunderlying ground water. Both leachate col-lection and removal systems and leak detec-

tion systems serve this purpose. You shouldconsult with the state agency too determine ifsuch systems are required. The primary func-tion of a leachate collection and removal sys-tem is to collect and convey leachate out of aunit and to control the depth of leachateabove a liner. The primary function of a leakdetection system is to detect leachate that hasescaped the primary liner. A leak detectionsystem refers to drainage material locatedbelow the primary liner and above a sec-ondary liner (if there is one); it acts as a sec-ondary leachate collection and removalsystem. After the leachate has been removedand collected, a leachate treatment systemmight be incorporated to process the leachateand remove harmful constituents.

The information in this section on leachatecollection and leak detection systems isapplicable if the unit is a landfill or a wastepile. Surface impoundments, which manageliquid wastes, usually will not have leachatecollection and removal systems unless theywill be closed in-place as landfills; they mighthave leak detection systems to detect liquidwastes that have escaped the primary liner.Leachate collection or leak detection systemsgenerally are not used with land application.

A. Leachate CollectionSystem

A typical leachate collection systemincludes a drainage layer, collection pipes, aremoval system, and a protective filter layer.Leachate collection systems are designed tocollect leachate for treatment or alternate dis-posal and to reduce the buildup of leachateabove the liner system. Figure 4 shows across section of a typical leachate collectionsystem showing access to pipes for cleaning.

7B-24



for leachate collection and

removal systems?

You should design a leachate collection andremoval system to maintain less than 30 cm(12 in.) depth of leachate, or “head,” abovethe liner if granular soil or a geosyntheticmaterial is used. The reason for maintainingthis level is to prevent excessive leachate frombuilding up above the liner, which couldjeopardize the liner’s performance. Thisshould be the underlying factor guiding thedesign, construction, and operation of theleachate collection and removal system.

You should design a leachate collectionand removal system capable of controlling theestimated volume of leachate. To determine

potential leachate generation, you should usewater balance equations or models. The mostcommonly used method to estimate leachategeneration is EPA’s Hydrogeologic Evaluationof Landfill Performance (HELP) model.21 Thismodel uses weather, soil, and waste manage-ment unit design data to determine leachategeneration rates.


ered in the design of a leachate

collection and removal system?

You should design a leachate collectionand removal system to include the followingelements: a low-permeability base, a high-permeability drainage layer, perforatedleachate collection pipes, a protective filterlayer, and a leachate removal system. During


7B-25

21 Available on the CD-ROM version of the Guide, as well as from the U.S. Army Corps of Engineers Website <www.wes.army.mil/el/elmodels/index.html#landfill>

Source: U.S. EPA, 1995b

Figure 4

Typical Leachate Collection System

design, you should consider the stability ofthe base, the transmissivity of the drainagelayers, and the strength of the collectionpipes. It is also prudent to consider methodsto minimize physical, biological, and chemi-cal clogging within the system.

Low-Permeability BaseA leachate collection system is placed over

the unit’s liner system. The bottom linershould have a minimum slope of 2 percent toallow the leachate collection system to gravityflow to a collection sump. This grade is nec-essary to provide proper leachate drainagethroughout the operation, closure, and post-closure of the unit. Estimates of foundationsoil settlement should include this 2 percentgrade as a post-settlement design.

High-Permeability Drainage LayerA high-permeability drainage layer consists

of drainage materials placed directly over thelow-permeability base, at the same minimum2 percent grade. The drainage materials canbe either granular soil or geosynthetic materi-als. For soil drainage materials, a maximum of12 inches of materials with a hydraulic con-ductivity of at least 1 x 10-2 cm/sec (4 x 10-3

in/sec) is recommended. For this reason, sandand gravel are the most common soil materi-als used. If the drainage layer is going toincorporate sand or gravel, it should bedemonstrated that the layer will have suffi-cient bearing capacity to withstand the wasteload of the full unit. Additionally, if the wastemanagement unit is designed on grades of 15percent or higher, it should be demonstratedthat the soil drainage materials will be stableon the steepest slope in the design.

Geosynthetic drainage materials such asgeonets can be used in addition to, or in placeof, soil materials. Geonets promote rapidtransmission of liquids and are most effective

when used in conjunction with a filter layeror geotextile to prevent clogging. Geonetsconsist of integrally connected parallel sets ofplastic ribs overlying similar sets at variousangles. Geonets are often used on the sidewalls of waste management units because oftheir ease of installation. Figure 5 depicts atypical geonet material configuration.

The most critical factor involved with usinggeonets in a high-permeability drainage layeris the material’s ability to transmit fluidsunder load. The flow rate of a geonet can beevaluated by ASTM D-4716.22 Several addi-tional measures for determining the transmis-sivity of geonets are discussed in the SolidWaste Disposal Facility Criteria: TechnicalManual (U.S. EPA, 1993b).

Perforated Leachate Collection PipesWhenever the leachate collection system is

a natural soil, a perforated piping systemshould be located within it to rapidly trans-mit the leachate to a sump and removal sys-tem. Through the piping system, leachateflows gravitationally to a low point where thesump and removal system is located. Thedesign of perforated leachate collection pipes,therefore, should consider necessary flowrates, pipe sizing, and pipe structuralstrength. After estimating the amount ofleachate using the HELP model or a similarwater balance model, it is possible to calcu-late the appropriate pipe diameter and spac-ing. For the leachate collection systemdesign, you should select piping material thatcan withstand the anticipated weight of thewaste, construction and operating equipmentstresses, and foundation settling. Mostleachate collection pipes used in modernwaste management units are constructed ofHDPE. HDPE pipes provide great structuralstrength, while allowing significant chemicalresistance to the many constituents found inleachate. PVC pipes are also used in waste

7B-26

22 ASTM D-4716, Standard Test Method for Constant Head Hydraulic Transmissivity (In-Plane Flow) ofGeotextiles and Geotextile Related Products.


management units, but they are not as chemi-cally resistant as HDPE pipes.

Protective Filter LayerTo protect the drainage layer and perforat-

ed leachate collection piping from clogging,you should place a filter layer over the high-permeability drainage layer. To prevent wastematerial from moving into the drainage layer,the filter layer should consist of a materialwith smaller pore space than the drainagelayer materials or the perforation openings inthe collection pipes. Sand and geotextiles arethe two most common materials used for fil-tration. You should select sand that allowsadequate flow of liquids, prevents migrationof overlying solids or soils into the drainagelayer, and minimizes clogging during the ser-vice life. In designing the sand filter, youshould consider particle size and hydraulicconductivity. The advantages of using sandmaterials include common usage, traditionaldesign, and durability.

Any evaluation of geotextile materialsshould address the same concerns but with afew differences. To begin with, the averagepore size of the geotextile should be largeenough to allow the finer soil particles to pass

but small enough toretain larger soil parti-cles. The number ofopenings in the geotex-tile should be largeenough that, even ifsome of the openingsclog, the remainingopenings will be suffi-cient to pass the designflow rate. In addition topore size, geotextile fil-ter specifications shouldinclude durabilityrequirements. Theadvantages of geotextile

materials include vertical space savings andeasy placement. Chapter 5 of TechnicalGuidance Document: Quality Assurance andQuality Control for Waste Containment Facilities(U.S. EPA, 1993c) offers guidance on protec-tion of drainage layers.

Leachate Removal SystemLeachate removal often involves housing a

sump within the leachate collection drainagelayer. A sump is a low point in the liner con-structed to collect leachate. Modern wastemanagement unit sumps often consist of pre-fabricated polyethylene structures supportedon a steel plate above the liner. Especiallywith geomembrane liners, the steel plateserves to support the weight of the sump andprotect the liner from puncture. Gravel filledearthen depressions can serve as the sump.Reinforced concrete pipe and concrete floor-ing also can be used in place of the polyethyl-ene structure but are considerably heavier.

To remove leachate that has collected inthe sump, you should use a submersiblepump. Ideally, the sump should be placed ata depth of 1 to 1.5 m (3 to 5 ft) to allowenough leachate collection to prevent thepump from running dry. You should consider


7B-27

Figure 5

Typical Geonet Configuration

installing a level control, backup pump, andwarning system to ensure proper sump oper-ation. Also consider using a backup pump asan alternate to the primary pump and toassist it during high flow periods. A warningsystem should be used to indicate pump mal-function.

Standpipes, vertical pipes extendingthrough the waste and cover system, offerone method of removing leachate from asump without puncturing the liner.Alternatively, you can remove leachate from asump using pipes that are designed to pene-trate the liner. When installing pipe penetra-tions through the liner, you should proceedwith extreme caution to prevent any linerdamage that could result in uncontainedleachate. Both of these options rely on gravityto direct leachate to a leachate collectionpond or to an external pumping station.

Minimizing CloggingLeachate collection and removal systems

are susceptible to physical, biological, andchemical clogging. Physical clogging canoccur through the migration of finer-grainedmaterials into coarser-grained materials, thusreducing the hydraulic conductivity of thecoarser-grained material. Biological cloggingcan occur through bacterial growth in thesystem due to the organic and nutrient mate-rials in leachate. Chemical clogging can becaused by chemical precipitates, such as cal-cium carbonates, causing blockage or cemen-tation of granular drainage material.

Proper selection of drainage and filter mate-rials is essential to minimize clogging in thehigh-permeability drainage layer. Soil and geo-textile filters can be used to minimize physicalclogging of both granular drainage materialand leachate collection pipes. When placedabove granular drainage material, these filterscan also double as an operations layer to pre-vent sharp waste from damaging the liner or

leachate collection and removal systems. Tominimize chemical and biological clogging forgranular drainage material, the best procedureis to keep the interstices of the granulardrainage material as open as possible.

The leachate collection pipes are also sus-ceptible to similar clogging. To prevent this,you should incorporate measures into thedesign to allow for routine pipe cleaning,using either mechanical or hydraulic meth-ods. The cleaning components can includepipes with a 15 cm (6 in) minimum diameterto facilitate cleaning; access located at majorpipe intersections or bends to allow forinspections and cleaning; and valves, ports,or other appurtenances to introduce biocidesand cleaning solutions. Also, you shouldcheck that the design does not include wrap-ping perforated leachate collection pipesdirectly with geotextile filters. If the geotex-tile becomes clogged, it can block flow intothe pipe.

B. Leak Detection SystemThe leak detection system (LDS) is also

known as the secondary leachate collectionand removal system. It uses the samedrainage and collection components as theprimary leachate collection and removal sys-tem and identifies, collects, and removes anyleakage from the primary system. The LDSshould be located directly below the primaryliner and above the secondary liner.


for leak detection systems?

The LDS should be designed to assess theadequacy of the primary liner againstleachate leakage; it should cover both thebottom and side walls of a waste manage-ment unit. The LDS should be designed tocollect leakage through the primary layer andtransport it to a sump within 24 hours.

7B-28


The LDS should allow for monitoring andcollection of leachate escaping the primaryliner system. You should monitor the LDS ona regular basis. If the volume of leachatedetected by the LDS appears to be increasingor is significant, you should consider a closerexamination to determine possible remedia-tion measures. A good rule of thumb is that ifthe LDS indicates a seepage level greater than20 gallons per acre per day, the system mightneed closer monitoring or remediation.

C. Leachate TreatmentSystem

Once the leachate has been removed fromthe unit and collected, you should considertaking measures to characterize the leachatein order to ensure proper management. Thereare several methods of disposal for leachate,and the treatment strategy will vary accordingto the disposal method chosen. Leachate dis-posal options include discharging to orpumping and hauling to a publicly ownedtreatment works or to an onsite treatmentsystem; treating and discharging to the envi-ronment; land application; and natural ormechanical evaporation.

When discharging to or pumping andhauling leachate to a publicly owned treat-ment works, a typical treatment strategyincludes pretreatment. Pretreatment couldinvolve equalization, aeration, sedimentation,pH adjustment, or metals removal.23 If theplan for leachate disposal does not involve aremote treatment facility, pretreatment aloneusually is not sufficient.

There are two categories of leachate treat-ment, biological and physical/chemical. Themost common method of biological treatmentis activated sludge. Activated sludge is a “sus-pended-growth process that uses aerobicmicroorganisms to biodegrade organic contam-inants in leachate.”24 Among physical/chemical

treatment techniques, the carbon absorptionprocess and reverse osmosis are the two mostcommon methods. Carbon absorption usescarbon to remove dissolved organics fromleachate and is very expensive. Reverse osmo-sis involves feeding leachate into a tubularchamber whose wall acts as a synthetic mem-brane, allowing water molecules to passthrough but not pollutant molecules, therebyseparating clean water from waste constituents.


for leachate treatment systems?

You should review all applicable federaland state regulations and discharge standardsto determine which treatment system willensure long-term compliance and flexibilityfor the unit. Site-specific factors will also playa fundamental role in determining the properleachate treatment system. For some facilities,onsite storage and treatment might not be anoption due to space constraints. For otherfacilities, having a nearby, publicly ownedtreatment works might make pretreatmentand discharge to the treatment works anattractive alternative.

VI. ConstructionQualityAssurance andQuality Control

Even the best unit design will not translateinto a structure that is protective of humanhealth and the environment, if the unit is notproperly constructed. Manufacturing qualityassurance and manufacturing quality control(MQA and MQC) are also important issuesfor the overall project; however, they are dis-cussed only briefly here since they are pri-marily the responsibility of a manufacturer.Nonetheless, it is best to select a manufactur-


7B-29

23 Arts, Tom. “Alternative Approaches For Leachate Treatment.” World Wastes.

24 Ibid.

er who incorporates appropriate qualityassurance and quality control (QA and QC)mechanisms as part of the manufacturingprocess. The remainder of this section pro-vides a general description of the compo-nents of a construction quality assurance andconstruction quality control (CQA and CQC)program for a project. CQA and CQC arecritical factors for waste management units.They are not interchangeable, and the dis-tinction between them should be kept inmind when preparing plans. CQA is thirdparty verification of quality, while CQC con-sists of in-process measures taken by the con-tractor or installer to maintain quality. Youshould establish clear protocols for identify-ing and addressing issues of concernthroughout every stage of construction.

What is manufacturing quality

assurance?

The desired characteristics of liner materi-als should be specified in the unit’s contractwith the manufacturer. The manufacturershould be responsible for certifying that mate-rials delivered conform to those specifications.MQC implemented to ensure such confor-mance might take the form of process qualitycontrol or computer-aided quality control. Ifrequested, the manufacturer should provideinformation on the MQC measures used,allow unit personnel or engineers to visit themanufacturing facility, and provide liner sam-ples for testing. It is good practice for themanufacturer to have a dedicated individualin charge of MQC who would work with unitpersonnel in these areas.

What is construction quality

assurance?

CQA is a verification tool employed by thefacility manager or regulatory agency, consist-ing of a planned series of observations andtests designed to ensure that the final prod-

uct meets project specifications. CQA testing,often referred to as acceptance inspection,provides a measure of the final product quali-ty and its conformance with project plansand specifications. Performing acceptanceinspections routinely, as portions of the pro-ject become complete, allows early detectionand correction of deficiencies, before theybecome large and costly.

On routine construction projects, CQA isnormally the concern of the facility managerand is usually performed by an independent,third-party testing firm. The independence ofthe testing firm is important, particularlywhen a facility manager has the capacity toperform the CQA activities. Although the

7B-30


MQC, MQA, CQC, and CQAManufacturing quality control

(MQC) is measures taken by the manu-facturer to ensure compliance with thematerial and workmanship specificationsof the facility manager.

Manufacturer quality assurance(MQA) is measures taken by facility per-sonnel, or by an impartial party broughtin expressly for the purpose, to deter-mine if the manufacturer is in compli-ance with the specifications of the facilitymanager.

Construction quality control (CQC)is measures taken by the installer or con-tractor to ensure compliance with theinstallation specifications of the facilitymanager.

Construction quality assurance(CQA) is measures taken by facility per-sonnel, or by an impartial party broughtin expressly for the purpose, to deter-mine if the installer or contractor is incompliance with the installation specifi-cations of the facility manager.

facility’s in-house CQA personnel might beregistered professional engineers, a perceptionof misrepresentation might arise if CQA is notperformed by an independent third party.

The independent party should designate aCQA officer and fully disclose any activitiesor relationships that the officer has with thefacility manager that might impact his or herimpartiality or objectivity. If such activities orrelationships exist, the CQA officer shoulddescribe actions that have been or can betaken to avoid, mitigate, or neutralize thepossibility they might affect the CQA officer’sobjectivity. State regulatory representativescan help evaluate whether these mechanismsare sufficient to ensure acceptable CQA.

What is construction quality

control?

CQC is an ongoing process of measuringand controlling the characteristics of the prod-uct in order to meet manufacturer’s or projectspecifications. CQC inspections are typicallyperformed by the contractor to provide an in-process measure of construction quality andconformance with the project plans and speci-fications, thereby allowing the contractor tocorrect the construction process if the qualityof the product is not meeting the specifica-tions and plans. Since CQC is a productiontool employed by the manufacturer of materi-als and by the contractor installing the materi-als at the site, the Guide does not cover CQCin detail. CQC is performed independently ofCQA. For example, while a geomembraneliner installer will perform CQC testing offield seams, the CQA program should requireindependent testing of those same seams by athird-party inspector.

How can implementation of CQA

and CQC plans be ensured?

When preparing to design and construct awaste management unit, regardless of design,you should develop CQA and CQC planscustomized to the project. To help the projectrun smoothly, the CQA plan should be easyto follow. You should organize the CQA planto reflect the sequence of construction andwrite it in language that will be familiar to anaverage field technician. For a more detaileddiscussion of specific CQA and CQC activi-ties recommended for each type of wastemanagement unit, you should consultTechnical Guidance Document: QualityAssurance and Quality Control for WasteManagement Containment Facilities (U.S. EPA,1993c). This document provides informationto develop comprehensive QA plans and tocarry out QC procedures at waste manage-ment units.

CQA and CQC plans can be implementedthrough a series of meetings and inspections,which should be documented thoroughly.Communication among all parties involved indesign and construction of a waste manage-ment unit is essential to ensuring a qualityproduct. You should define responsibility andauthority in written QA and QC plans andensure that each party involved understandsits role. Pre-construction meetings are oneway to help clarify roles and responsibilities.During construction, meetings can continueto be useful to help resolve misunderstandingsand to identify solutions to unanticipatedproblems that might develop. Some examplesof typical meetings during the course of anyconstruction project include pre-bid meetings,resolution meetings, pre-construction meet-ings, and progress meetings.


7B-31

A. Compacted Clay LinerQuality Assurance andQuality Control

Although manufacturing quality controland quality assurance are often the responsi-bility of the materials manufacturer, in thecase of soil components, manufacturing andconstruction quality control testing can bethe responsibility of the facility manager. TheCQA and CQC plans should specify proce-dures for quality assurance and quality con-trol during construction of the compactedclay liners.

How can implementation of QA

and QC be ensured for a com-

pacted clay liner?

QC testing is typically performed by thecontractor on materials used in constructionof the liner. This testing examines materialproperties such as moisture content, soil den-sity, Atterberg limits, grain size, and laborato-ry hydraulic conductivity. Additional testingof soil moisture content, density, lift thick-ness, and hydraulic conductivity helps ensurethat the waste management unit has beenconstructed in accordance with the plans andtechnical specifications.

CQA testing for soil liners includes thesame tests described for QC testing in theparagraph above. Generally, the tests are per-formed less frequently. CQA testing is per-formed by an individual or an entityindependent of the contractor. Activities ofthe CQA officer are essential to documentquality of construction. The responsibilitiesof the CQA officer and his or her staff mightinclude communicating with the contractor;interpreting and clarifying project drawingsand specifications with the designer, facilitymanager, and contractor; recommendingacceptance or rejection by the facility manag-er of work completed by the construction

contractor; and submitting blind samples,such as duplicates and blanks, for analysis bythe contractor’s testing staff or independentlaboratories.

You should also consider constructing atest pad prior to full-scale construction as aCQA tool. As described earlier in the sectionon compacted clay liners, pilot constructionor test fill of a small-scale test pad can beused to verify that the soil, equipment, andconstruction procedures can produce a linerthat performs according to the constructiondrawings and specifications.

Specific factors to examine or test duringconstruction of a test fill include: preparationand compaction of foundation material to therequired bearing strength; methods of con-trolling uniformity of the soil material; com-pactive effort, such as type of equipment andnumber of passes needed to achieve requiredsoil density and hydraulic conductivity; andlift thickness and placement proceduresneeded to achieve uniformity of densitythroughout a lift and prevent boundaryeffects between lifts or between placements inthe same lift. Test pads can also provide ameans to evaluate the ability of differenttypes of soil to meet hydraulic conductivityrequirements in the field. In addition toallowing an opportunity to evaluate materialperformance, test pads also allow evaluationof the skill and competence of the construc-tion team, including equipment operatorsand QC specialists.

B. Geomembrane LinerQuality Assurance andQuality Control

As with the construction of soil liners,installation of geomembrane liners should bein conformance with a CQA and CQC plan.The responsibilities of the CQA personnel forthe installation of the geomembrane are gen-

7B-32


erally the same as the responsibilities for theconstruction of a compacted clay liner, withthe addition of certain activities includingobservations of the liner storage area and lin-ers in storage, and handling of the liner as thepanels are positioned in the cell.Geomembrane CQA staff should also observeseam preparation, seam overlap, and materi-als underlying the liner.


and QC be ensured for a

geomembrane liner?

Prior to installation, you should work withthe geomembrane manufacturer to ensure thelabeling system for the geomembrane rolls isclear and logical, allowing easy tracking of theplacement of the rolls within the unit. It isimportant to examine the subgrade surfacewith both the subgrade contractor and the linerinstaller to ensure it conforms to specifications.

Once liner installation is underway, CQAstaff might be responsible for observations ofdestructive testing conducted on scrap testwelds prior to seaming. Geomembrane CQAstaff might also be responsible for sendingdestructive seam sampling to an independenttesting laboratory and reviewing the results forconformance to specifications. Other observa-tions for which the CQA staff are typicallyresponsible include observations of all seamsand panels for defects due to manufacturingand handling, and placement and observationsof all pipe penetrations through a liner.

Test methods, test parameters, and testingfrequencies should be specified in the CQAplan to provide context for any data collect-ed. It is prudent to allow for testing frequen-cy to change, based on the performance ofthe geomembrane installer. If test results indi-cate poor workmanship, you should increasetesting. If test results indicate high qualityinstallation work, you can consider reducing

testing frequencies. When varying testing fre-quency, you should establish well-definedprocedures for modifying testing frequency. Itis also important to evaluate testing methods,understand the differences among testingmethods, and request those methods appro-priate for the material and seaming methodbe used. Nondestructive testing methods arepreferrable when possible to help reduce thenumber of holes cut into the geomembrane.

Geomembrane CQA staff also should docu-ment the results of their observations and pre-pare reports indicating the types of samplingconducted and sampling results, locations ofdestructive samples, locations of patches,locations of seams constructed, and any prob-lems encountered. In some cases, they mightneed to prepare drawings of the liner installa-tion. Record drawing preparation is frequentlyassigned to the contractor, to a representativeof the facility manager, or to the engineer. Youshould request complete reports from anyCQA staff and the installers. To ensure com-plete CQA documentation, it is important tomaintain daily CQA reports and prepareweekly summaries.

C. Geosynthetic Clay LinerQuality Assurance andQuality Control

Construction quality assurance for geosyn-thetic clay liners is still a developing area; theGCL industry is continuing to establish stan-dardized quality assurance and quality con-trol procedures. The CQA recommendationfor GCLs can serve as a starting point. Youshould check with the GCL manufacturer andinstaller for more specific information.


7B-33


and QC be ensured for a geosyn-

thetic clay liner?

It is recommended that you develop adetailed CQA plan, including product speci-fications; shipping, handling, and storageprocedures; seaming methods; and placementof overlying material. It is important to workwith the manufacturer to verify that theproduct meets specifications. Upon receipt ofthe GCL product, you should also verify thatit has arrived in good condition.

During construction, CQA staff shouldensure that seams are overlapped properlyand conform to specifications. CQA staffshould also check that panels, not deployedwithin a short period of time, are storedproperly. In addition, as overlying material isplaced on the GCL, it is important to restrictvehicle traffic directly on the GCL. Youshould prohibit direct vehicle traffic, with theexception of small, 4-wheel, all terrain vehi-cles. Even with the small all-terrain vehicles,drivers should take extreme care to avoidmovements, such as sudden starts, stops, andturns, which can damage the GCL.

As part of the CQA documentation, it isimportant to maintain records of weatherconditions, subgrade conditions, and GCLpanel locations. Also, you should documentany repairs that were necessary or otherproblems identified and addressed.

D. Leachate CollectionSystem QualityAssurance and QualityControl

Leachate collection system CQC should beperformed by the contractor. Similar activi-ties should be performed for CQA by anindependent party acting on behalf of the

facility manager. The purpose of leachate col-lection system CQA is to document that thesystem is constructed in accordance withdesign specifications.


and QC be ensured for a

leachate collection system?

Prior to construction, CQA staff shouldinspect all materials to confirm that they meetthe construction plans and specifications.These materials include: geonets; geotextiles;pipes; granular material; mechanical, electri-cal, and monitoring equipment; concreteforms and reinforcements; and prefabricatedstructures such as sumps and manholes. Theleachate collection system foundation, either ageomembrane or compacted clay liner, shouldalso be inspected, upon its completion, toensure that it has proper grading and is freeof debris and liquids.

During construction, CQA staff shouldobserve and document, as appropriate, theplacement and installation of pipes, filter lay-ers, drainage layers, geonets and geotextiles,sumps, and mechanical and electrical equip-ment. For pipes, observations might includedescriptions of pipe bedding material, qualityand thickness, as well as the total area cov-ered by the bedding material. Observationsof pipe installations should focus on the loca-tion, configuration, and grading of the pipes,as well as the quality of connections at joints.

For granular filter layers, CQA activitiesmight include observing and documentingmaterial thickness and quality during place-ment. For granular drainage layers, CQAmight focus on the protection of underlyingliners, material thickness, proper overlapwith filter fabrics and geonets (if applicable),and documentation of any weather condi-tions that might affect the overall perfor-mance of the drainage layer. For geonets and

7B-34


other geosynthetics, CQA observationsshould focus on the area of coverage and lay-out pattern, as well as the overlap betweenpanels. For geonets, CQA staff might want tomake sure that the materials do not becomeclogged by granular material that can be car-ried over, as a result of either wind or runoffduring construction.

Upon completion of construction, eachcomponent should be inspected to identifyany damage that might have occurred duringits installation or during construction ofanother component. For example, a leachatecollection pipe can be crushed during place-ment of a granular drainage layer. Any dam-age that does occur should be repaired, andthe repairs should be documented in theCQA records.


7B-35

7B-36


■■■■ Review the recommended location considerations and operating practices for the unit.

■■■■ Select appropriate liner type—single, composite, or double liner—or in-situ soils, based on riskcharacterization.

■■■■ Evaluate liner material properties and select appropriate clay, geosynthetic, or combination of mate-rials; consider interactions of liner and soil material with waste.

■■■■ Develop a construction quality assurance (CQA) plan defining staff roles and responsibilities andspecifying test methods, storage procedures, and construction protocols.

■■■■ Ensure a stable in-situ soil foundation, for nonengineered liners.

■■■■ Prepare and inspect subgrade for engineered liners.

■■■■ Work with manufacturer to ensure protective shipping, handling, and storage of all materials.

■■■■ Construct a test pad for compacted clay liners.

■■■■ Test compacted clay liner material before and during construction.

■■■■ Preprocess clay material to ensure proper water content, remove oversized particles, and add soilamendments, as applicable.

■■■■ Use proper lift thickness and number of equipment passes to achieve adequate compaction.

■■■■ Protect clay material from drying and cracking.

■■■■ Develop test strips and trial seams to evaluate geomembrane seaming method.

■■■■ Verify integrity of factory and field seams for geomembrane materials before and during construction.

■■■■ Backfill with soil or geosynthetics to protect geomembranes and geosynthetic clay liners duringconstruction.

■■■■ Place backfill materials carefully to avoid damaging the underlying materials.

■■■■ Install geosynthetic clay liner with proper overlap.

■■■■ Patch any damage that occurs during geomembrane or geosynthetic clay liner installation.

■■■■ Design leachate collection and removal system to allow adequate flow and to minimize clogging;include leachate treatment and leak detection systems, as appropriate.

■■■■ Document all CQA activities, including meetings, inspections, and repairs.

Designing and Installing Liners Activity List


7B-37

ASTM D-413. 1993. Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.

ASTM D-422. 1990. Standard Test Method for Particle-Size Analysis of Soils.

ASTM D-638. 1991. Standard Test Method for Tensile Properties of Plastics.

ASTM D-698. 1991. Test Method for Laboratory Compaction Characteristics of Soil Using StandardEffort (12,400 ft-lbf/ft3 (600 kN-m/m3)).

ASTM D-751. 1989. Standard Test Methods for Coated Fabrics.

ASTM D-882. 1991. Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.

ASTM D-1004. 1990. Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting.

ASTM D-1557. 1991. Test Method for Laboratory Compaction Characteristics of Soil Using ModifiedEffort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)).

ASTM D-4318. 1993. Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index ofSoils.

ASTM D-4354. 1989. Standard Practice for Sampling of Geosynthetics for Testing.

ASTM D-4716. 1987. Standard Test Method for Constant Head Hydraulic Transmissivity (In-PlaneFlow) of Geotextiles and Geotextile Related Products.

ASTM D-5084. 1990. Standard Test Method for Measurement of Hydraulic Conductivity of SaturatedPorous Materials Using a Flexible Wall Permeameter.

ASTM D-5199. 1991. Standard Test Method for Measuring Nominal Thickness of Geotextiles andGeomembranes.

ASTM D-5261. 1992. Standard Test Method for Measuring Mass per Unit Area of Geotextiles.

ASTM D-5321. 1992. Standard Test Method for Determining the Coefficient of Soil and Geosyntheticor Geosynthetic and Geosynthetic Friction by the Direct Shear Method.

Resources

7B-38


Resources (cont.)

Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills.

Berg, R., and L. Well. 1996. A Position Paper on: The Use of Geosynthetic Barriers in NonhazardousIndustrial Waste Containment.

Berger, E. K. and R. Berger. 1997. The Global Water Cycle.

Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields. <hermes.ecn.purdue.edu/cgi/con-vwqtest?/b-803.wy.ascii>

Boulding, J.R. 1995. Practical Handbook of Soil, Vadose Zone, and Ground Water Contamination:Assessment, Prevention and Remediation. Lewis Publishers.

Brandt, R.C. and K.S. Martin. 1996. The Food Processing Residual Management Manual. September.

Daniel, D.E., and R.M. Koerner. 1991. Landfill Liners from Top to Bottom. Civil Engineering. December.

Daniel, D.E., and R.M. Koerner. 1993. Technical Guidance Document: Quality Assurance and QualityControl for Waste Containment Facilities. Prepared for U.S. EPA. EPA600-R-93-182.

Daniel, D.E., and R.M. Koerner. 1995. Waste Containment Facilities: Guidance for Construction, QualityAssurance and Quality Control of Liner and Cover Systems.

Evanylo, G.K. and W. L. Daniels. 1996. The Value and Suitability of Papermill Sludge and SludgeCompost as a Soil Amendment and Soilless Media Substitute. Final Report. The Virginia Department ofAgriculture and Consumer Services, P.O. Box 1163, Room 402, Richmond, VA. April.

Federal Test Method Standard 101C. 1980. Puncture Resistance and Elongation Test (1/8 Inch RadiusProbe Method).

Fipps, G. 1995. Managing Irrigation Water Salinity in the Lower Rio Grande Valley. <hermes.ecn.pur-due.edu/sgml/water_quality/texas/b1667.ascii>

Geosynthetic Research Institute. 1993. GRI-GCL1, Swell Measurement of the Clay Component of GCLs.

Geosynthetic Research Institute. 1993. GRI-GCL2, Permeability of Geosynthetic Clay Liners (GCLs).


7B-39

Resources (cont.)

Idaho Department of Health and Welfare. 1988. Guidelines for Land Application of Municipal andIndustrial Wastewater. March.

Koerner, R.M. 1994. Designing with Geosynthetics, Third Edition.

McGrath, L., and P. Creamer. 1995. Geosynthetic Clay Liner Applications in Waste DisposalFacilities.

McGrath, L., and P. Creamer. 1995. Geosynthetic Clay Liner Applications. Waste Age. May.

Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guidance for LandApplication of Wastewater Sludge in Michigan. March.

Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guide to Preparinga Residuals Management Plan. March.

Minnesota Pollution Control Agency. 1993. Land Treatment of Landfill Leachate. February.

Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Nutrient ManagementSoftware: Proceedings from the Nutrient Management Software Workshop. NRAES-100. December.

Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Animal Agriculture andthe Environment: Nutrients, Pathogens, and Community Relations. NRAES-96. December.

Northeast Regional Agricultural Engineering Cooperative Extension. 1993. Utilization of FoodProcessing Residuals. Selected Papers Representing University, Industry, and RegulatoryApplications. NRAES-69. March.

North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling - The Key toReliable Soil Test Information. AG-439-30.

Oklahoma Department of Environmental Quality. Title 252. Oklahoma Administrative Code,Chapter 647. Sludge and Land Application of Wastewater.

Sharma, H., and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and Landfills:Design and Evaluation.

Smith, M.E., S. Purdy, and M. Hlinko. 1996. Some Do’s and Don’ts of Construction QualityAssurance. Geotechnical Fabrics Report. January/February.

7B-40


Resources (cont.)Spellman, F. R. 1997. Wastewater Biosolids to Compost.

Texas Water Commission. 1983. Industrial Solid Waste Management Technical Guideline No. 5: LandApplication. December.

Tsinger, L. 1996. Chemical Compatibility Testing: The State of Practice. Geotechnical Fabrics Report.October/November.

University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991.Guidelines for Soil Sampling. G91-1000-A. February.

U.S. EPA. 2001. Technical Resource Document: Assessment and recommendations for Improving thePerformance of Waste Containment Systems. Draft.

U.S. EPA. 1996a. Issue Paper on Geosynthetic Clay Liners (GCLs).

U.S. EPA. 1996b. Report of 1995 Workshop on Geosynthetic Clay Liners. EPA600-R-96-149. June.

U.S. EPA. 1995a. A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule. EPA832-B-93-005. September.

U.S. EPA. 1995b. Decision Maker’s Guide to Solid Waste Management. Volume II. EPA530-R-95-023.

U.S. EPA. 1995c. Laboratory Methods for Soil and Foliar Analysis in Long-Term EnvironmentalMonitoring Programs. EPA600-R-95-077.

U.S. EPA. 1995d. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage.EPA625-R-95-001. September.

U.S. EPA. 1995e. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage.EPA625-R-95-002. September.

U.S. EPA. 1994a. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA832-R-93-003.September.

U.S. EPA. 1994b. Biosolids Recycling: Beneficial Technology for a Better Environment. EPA832-R-94-009. June.

U.S. EPA. 1994c. Guide to Septage Treatment and Disposal. EPA625-R-94-002. September.


7B-41

Resources (cont.)U.S. EPA. 1994d. Land Application of Sewage Sludge: A Guide for Land Appliers on the Requirementsof the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503. EPA831-B-93-002b. December.

U.S. EPA. 1994e. Seminar Publication: Design, Operation, and Closure of Municipal Solid WasteLandfills. EPA625-R-94-008.

U.S. EPA. 1993a. Domestic Septage Regulatory Guidance: A Guide to the EPA 503 Rule. EPA832-B-92-005. September.

U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.

U.S. EPA. 1993c. Technical Guidance Document: Quality Assurance and Quality Control for WasteContainment Facilities. EPA600-R-93-182.

U.S. EPA. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge. EPA625-R-92-013.December.

U.S. EPA. 1991a. Seminar Publication: Design and Construction of RCRA/CERCLA Final Covers.EPA625-4-91-025.

U.S. EPA. 1991b. Seminar Publication: Site Characterization for Subsurface Remediation. EPA625-4-91-026.

U.S. EPA. 1991c. Technical Guidance Document: Inspection Techniques for the Fabrication ofGeomembrane Field Seams. EPA530-SW-91-051.

U.S. EPA. 1990. State Sludge Management Program Guidance Manual. October.

U.S. EPA. 1989a. Seminar Publication: Requirements for Hazardous Waste Landfill Design,Construction, and Closure. EPA625-4-89-022.

U.S. EPA. 1989b. Seminar Publication: Corrective Action: Technologies and Applications. EPA625-4-89-020.

U.S. EPA. 1988. Lining of Waste Containment and Other Impoundment Facilities. EPA600-2-88-052.

U.S. EPA. 1987. Geosynthetic Guidance for Hazardous Waste Landfill Cells and Surface Impoundments.EPA600-2-87-097.

7B-42


Resources (cont.)U.S. EPA. 1986a. Project Summary: Avoiding Failure of Leachate Collection and Cap Drainage Systems.EPA600-S2-86-058.

U.S. EPA. 1986b. Test Methods for Evaluating Solid Waste: Physical/Chemical Methods. EPASW-846.

U.S. EPA. 1983. Process Design Manual for Land Application of Municipal Sludge. EPA625-1-83-016.October.

U.S. EPA, U.S. Army Corps of Engineers, U.S. Department of Interior, and U.S. Department ofAgriculture. 1981. Process Design Manual for Land Treatment of Municipal Wastewater. EPA625-1-81-013. October.

U.S. EPA. 1979. Methods for Chemical Analysis of Water and Wastes. EPA600-4-79-020.

Viessman Jr., W. and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th ed.

Washington State Department of Ecology. 1993. Guidelines for Preparation of Engineering Reports forIndustrial Wastewater Land Application Systems. Publication #93-36. May.

Webber, M.D. and S.S. Sing. 1995. Contamination of Agricultural Soils. In Action, D.F. and L.J.Gregorich, eds. The Health of Our Soils.

Wisconsin Department of Natural Resources. 1996. Chapter NR 518: Landspreading of Solid Waste. April.


7B-43

Geosynthetic Materials25

GeotextilesGeotextiles form one of the two largest

group of geosynthetics. Their rise in growthduring the past fifteen years has been nothingshort of awesome. They are indeed textiles inthe traditional sense, but consist of syntheticfibers rather than natural ones such as cotton,wool, or silk. Thus biodegradation is not aproblem. These synthetic fibers are made intoa flexible, porous fabric by standard weavingmachinery or are matted together in a ran-dom, or nonwoven, manner. Some are alsoknit. The major point is that they are porousto water flow across their manufactured planeand also within their plane, but to a widelyvarying degree. There are at least 80 specificapplication areas for geotextiles that have beendeveloped; however, the fabric always per-forms at least one of five discrete functions:

1. Separation

2. Reinforcement

3. Filtration

4. Drainage

5. Moisture barrier (when impregnated)

GeogridsGeogrids represent a rapidly growing seg-

ment within the geosynthetics area. Ratherthan being a woven, nonwoven or knit textile(or even a textile-like) fabric, geogrids areplastics formed into a very open, gridlikeconfiguration (i.e., they have large apertures).Geogrids are either stretched in one or twodirections for improved physical properties ormade on weaving machinery by uniquemethods. By themselves, there are at least 25

application areas, however, they functionalmost exclusively as reinforcement materials.

GeonetsGeonets, called geospacers by some, con-

stitute another specialized segment within thegeosynthetic area. They are usually formed bya continuous extrusion of parallel sets ofpolymeric ribs at acute angles to one another.When the ribs are opened, relatively largeapertures are formed into a netlike configura-tion. Their design function is completelywithin the drainage area where they havebeen used to convey fluids of all types.

GeomembranesGeomembranes represent the other largest

group of geosynthetics and in dollar volumetheir sales are probably larger than that ofgeotextiles. Their growth has been stimulatedby governmental regulations originally enact-ed in 1982. The materials themselves are“impervious” thin sheets of rubber or plasticmaterial used primarily for linings and coversof liquid- or solid-storage facilities. Thus theprimary function is always as a liquid orvapor barrier. The range of applications, how-ever, is very great, and at least 30 individualapplications in civil engineering have beendeveloped.

Geosynthetic Clay LinersGeosynthetic clay liners (or GCLs) are the

newest subset within geosynthetic materials.They are rolls of factory fabricated thin layersof bentonite clay sandwiched between twogeotextiles or bonded to a geomembrane.Structural integrity is maintained by needlepunching, stitching or physical bonding.They are seeing use as a composite compo-

25 Created by Geosynthetic Research Institute. Accessed from the Internet on October 16, 2001 at<www.drexel.edu/gri/gmat.html>.

Appendix

7B-44


nent beneath a geomembrane or by them-selves as primary or secondary liners.

Geopipe (aka Buried Plastic Pipe)Perhaps the original geosynthetic material

still available today is buried plastic pipe. This“orphan” of the Civil Engineering curriculumwas included due to an awareness that plasticpipe is being used in all aspects of geotechni-cal, transportation, and environmental engi-neering with little design and testingawareness. This is felt to be due to a generallack of formalized training. The critical natureof leachate collection pipes coupled with highcompressive loads makes geopipe a bona-fidemember of the geosynthetics family. The func-tion is clearly drainage.

GeocompositesA geocomposite consists of a combination

of geotextile and geogrid; or geogrid andgeomembrane; or geotextile, geogrid, and

geomembrane; or any one of these threematerials with another material (e.g.,deformed plastic sheets, steel cables, or steelanchors). This exciting area brings out thebest creative efforts of the engineer, manufac-turer, and contractor. The application areasare numerous and growing steadily. Themajor functions encompass the entire rangeof functions listed for geosynthetics discussedpreviously: separation, reinforcement, filtra-tion, drainage, and liquid barrier.

“Geo-Others”The general area of geosynthetics has

exhibited such innovation that many systemsdefy categorization. For want of a betterphrase, geo-others, describes items such asthreaded soil masses, polymeric anchors, andencapsulated soil cells. As with geocompos-ites their primary function is product-depen-dent and can be any of the five majorfunctions of geosynthetics.

Part IVProtecting Ground Water

Chapter 7: Section CDesigning A Land Application Program

ContentsI. Identifying Waste Constituents for Land Application..............................................................................7C-2

II. Evaluating Waste Parameters ..................................................................................................................7C-4

A. Total Solids Content ..............................................................................................................................7C-4

B. pH ........................................................................................................................................................7C-5

C. Biodegradable Organic Matter ..............................................................................................................7C-6

D. Nutrients ..............................................................................................................................................7C-6

E. Metals....................................................................................................................................................7C-8

F. Carbon-to-Nitrogen Ratio ......................................................................................................................7C-8

G. Soluble Salts ..........................................................................................................................................7C-9

H.Calcium Carbonate Equivalent ............................................................................................................7C-11

I. Pathogens ............................................................................................................................................7C-11

III. Measuring Soil Properties ....................................................................................................................7C-12

IV. Studying the Interaction of Plants and Microbes with Waste ................................................................7C-14

A. Greenhouse and Field Studies ............................................................................................................7C-15

B. Assessing Plant and Microbial Uptake Rates ........................................................................................7C-16

C. Effects of Waste on Plant and Microbe Growth....................................................................................7C-17

D. Grazing and Harvesting Restrictions....................................................................................................7C-18

V. Considering Direct Exposure, Ecosystem Impacts, & Bioaccumulation of Waste..................................7C-18

VI. Accounting for Climate ........................................................................................................................7C-19

VII. Calculating An Agronomic Application Rate ........................................................................................7C-19

VIII.Monitoring ..........................................................................................................................................7C-21

IX. Odor Controls ......................................................................................................................................7C-22

Designing a Land Application Program Activity List ..................................................................................7C-23

Resources ....................................................................................................................................................7C-24

Tables:

Table 1: Summary of Important Waste Parameters ....................................................................................7C-4

Table 2: Salinity Tolerance of Selected Crops ..........................................................................................7C-10

Table 3: EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils ......................................7C-11

Figures:

Figure 1: A Recommended Framework for Evaluating Land Application ..................................................7C-3

Figure 2: The Nitrogen Cycle ....................................................................................................................7C-7

Protecting Ground Water—Designing A Land Application Program

7C-1

Land application can be a beneficialand practical method for treating anddisposing of some wastes. Becauseland application does not rely on lin-ers to contain waste, however, there

are some associated risks. With proper planningand design, a land application program canmeet waste management and land preservationgoals, and avoid negative impacts such as nox-ious odors, long-term damage to soil, andreleases of contaminants to ground water, sur-face water, or the air. This chapter describes andrecommends a framework for addressing a vari-ety of waste parameters, in addition to the con-stituents outlined in Chapter 7, SectionA—Assessing Risk,1 and other factors such assoil properties and plant and microbial nutrientuse2 that can affect the ability of the land tosafely assimilate directly applied waste.Successful land application programs addressthe interactions among all these factors.

Some of the benefits of land applicationinclude:

• Biodegradation of waste. If a wastestream contains sufficient organicmaterial, plants and microorganismscan significantly biodegrade thewaste, assimilating its organic compo-nents into the soil. After allowing suf-ficient time for assimilation of thewaste, more waste can be applied to agiven site without significantlyincreasing the total volume of waste atthe site. This is in contrast to landfillsand waste piles, in which waste accu-mulates continually and generallydoes not biodegrade quickly enoughto reduce its volume significantly.

• Inclusion of liquids. Land applica-tion units can accept bulk, non-con-tainerized liquid waste. The water

1 The constituents incorporated in IWEM, including the heavy metals and synthetic organic chemicals,typically have little or no agricultural value and can threaten human health and the environment evenin small quantities. The term “waste parameters” as used in this section refers to some additional con-stituents such as nitrogen and biodegradable organic matter and other site-specific properties such aspH, that can have considerable agricultural significance and that can significantly impact human healthand the environment.

2 40 CFR Part 503 specifies requirements for land application of sludge from municipal sewage treatmentplants. The Part 503 regulations apply to sewage sludge (now generally referred to as “biosolids”) ormixtures of sewage sludge and industrial process wastes, not to industrial wastes alone. Some of thespecifications in Part 503, for example those concerning pathogens, might be helpful in evaluating landapplication of industrial wastes. For mixtures of sewage sludge and industrial waste, the ground-waterand air risk assessments and the framework laid out in the Guide can help address constituents that arenot covered under the Part 503 regulations.

Designing A Land Application ProgramThis chapter will help you:

• Assess the risks associated with waste constituents when consider-

ing application directly to the land as a soil amendment, or for

treatment, or disposal.

• Account for the designated ground-water constituents identified in

Chapter 7, Section A—Assessing Risk, as well as other waste para-

meters such as soil properties and plant and microbial interactions.

• Evaluate the capacity of the soil, vegetation, and microbial life to

safely assimilate the waste when developing an application rate.

7C-2


3 EPA has signed agreements with states, industries, and individual sites concerning land application. Oneexample is EPA’s Memorandum of Understanding (MOU) between the American Forest and PaperAssociation (AFPA) and the U.S. EPA Regarding the Implementation of the Land Application AgreementsAmong AF&PA Member Pulp and Paper Mills and the U.S. EPA, January 1994. For more information onthis MOU contact either AFPA’s Director of Industrial Waste Programs at 111 19th Street, N.W.,Washington, D.C. 20036 or EPA’s Director of the Office of Pollution Prevention and Toxics.

content of some liquid wastes makethem desirable at land applicationsites in arid climates. When managingliquid waste, land application canreduce the need for expensive dewa-tering processes.

• Improvement of soil. Applying wastedirectly to land can improve soil qual-ity if the waste contains appropriatelevels of biodegradable organic matterand nutrients. Nutrients can improvethe chemical composition of the soilto the extent that it can better supportvegetation, while biodegradable organ-ic matter can improve its physicalproperties and increase its waterretention capacity. This potential forchemical and physical improvementsthrough land application have led toits use in conditioning soil for agricul-tural use.

Figure 1 outlines a framework for evaluat-ing land application. This framework incorpo-rates both the ground-water risk assessmentmethodology recommended in Chapter 7,Section A–Assessing Risk, as well as the otherwaste parameters and factors important toland application.

I. IdentifyingWasteConstituents forLand Application

If a waste leachate contains any of the con-stituents covered in the IWEM ground-watermodel, you should first check with a federal,state, or other regulatory agency to see if thewaste constituents identified in the waste are

covered by any permits, MOUs, or other agree-ments concerning land application. The Guidedoes not supersede or modify conditions estab-lished in regulatory or other binding mecha-nisms, such as MOUs or agreements.3

Some wastes might be designated by stateor local regulators as essentially equivalent toa manufactured product or raw material. Suchdesignations usually are granted only whenuse of the designated waste would not presenta greater environmental and health risk thanwould use of the manufactured or raw materi-al it replaces. Equivalence designations areincluded in the category of “other agreements”above. If there are no designated ground-waterconstituents other than those on which thedesignation is based, then the guidelinesdescribed in this chapter can help you todetermine an appropriate application rate.

If the constituent(s) identified in the wasteis not currently covered under an agreement,IWEM or another site-specific model can helpyou determine whether land application of theconstituent(s) will be protective of groundwater. In some cases, pollution prevention ortreatment can lower constituents levels so thata waste can be land applied. In other cases,land application might not be feasible. In thisevent, you should pursue other waste manage-ment options. If your modeling results indi-cate that the constituents can be land applied,then the guidelines described in this chaptercan once again help you to determine anappropriate application rate.

Your modeling efforts should consider boththe direct exposure and ecosystem pathways.These pathways are extremely important inland application since waste is placed on theland and attenuated by the natural environ-ment rather than contained by an engineeredstructure.


7C-3

Figure 1. A Recommended Framework for Evaluating Land Application

Evaluate applicationrate. If waste streamexceeds rate, consider

additional managementmeasures

Identify waste constituents

Evaluate waste parameters

Follow terms ofpermit, MOU,or agreement

Yes

No

Evaluate IWEM constituents identified inthe waste to determine whether land appli-cation is protective of ground water using

IWEM or other risk assessment tool

No

Constituents should not be land appliedand you should treat wastes and

reassess land application potential oridentify other disposal options

Yes

Perform waste characterization• Ground-water constituents• Other waste parameters

Are all IWEM constituents identified in the wastecovered by permit, MOU, or other agreement?*

Measure soil parameters

Study interaction of plants and microbes

with waste

Consider direct expo-sure, ecosystem

impacts, and bioaccu-mulation of waste

Account for climate

Calculate agronomicapplication rate

* All constituents should have beenassessed and shown not to be a risk, or areaddressed by constituents directly covered

by MOU, permit, or other agreement.

7C-4


II. EvaluatingWasteParameters

In addition to the ground-water con-stituents designated in Chapter 7, SectionA–Assessing Risk, you should evaluate thewaste’s total solids content, pH, biodegradablematter, pathogens, nutrients, metals, carbonto nitrogen ratio, soluble salts, and calciumcarbonate equivalent when considering landapplication. These parameters provide thebasis for determining an initial waste applica-

tion rate and are summarized in Table 1. Afterthe initial evaluation, you should sample andcharacterize the waste on a regular basis andafter process changes that might affect wastecharacteristics to help determine whether youshould change application practices or con-sider other waste management options.

A. Total Solids ContentTotal solids content indicates the ratio of

solids to water in a waste. It includes bothsuspended and dissolved solids, and is usual-ly expressed as a percentage of the waste.

Waste Parameter Significance

Total solids content Indicates ratio of solids to water in waste and influences applicationmethod.

pH Controls metals solubility (and therefore mobility of metals towardground water) and affects biological processes.

Biodegradable organic matter Influences soil’s water holding capacity, cation exchange, and otherphysical and chemical properties, including odor.

Nutrients (nitrogen, phosphorus, Affect plant growth; nitrogen is a major determinant of application rate; and potassium) can contaminate ground water or cause phytotoxicity if applied in

excess.

Carbon to nitrogen ratio Influences availability of nitrogen to plants.

Soluble salts Can inhibit plant growth, reduce soil permeability, and contaminateground water.

Calcium carbonate equivalent Measures a waste’s ability to neutralize soil acidity.

Pathogens Can threaten public health by migrating to ground water or being car-ried by surface water, wind, or other vectors.

Ground-water constituents Can present public health risk through ground-water contamination, designated in Chapter 7, Section A– direct contact with waste-soil mix, transport by surface water, and Risk Assessment including metals accumulation in plants. Metals inhibit plant growth and can be and organic chemicals phytotoxic at elevated concentrations. Zinc, copper, and nickel are

micronutrients essential to plant growth, but can inhibit growth at highlevels.

Table 1Summary of Important Waste Parameters


7C-5

Total solids content depends on the type ofwaste, as well as whether the waste has beentreated prior to land application. If waste isdried, composted, dewatered, thickened, orconditioned prior to land application, watercontent is decreased, thereby increasing thetotal solids content (for some dry, fine, partic-ulate wastes, such as cement kiln dust, condi-tioning might involve adding water).4

Understanding the total solids content willhelp you develop appropriate storage andhandling procedures and establish an applica-tion rate. Total solids content also can affectyour choice of application method and equip-ment. Some methods, such as spray irriga-tion, might not work effectively if the solidscontent is too high. If it is low, meaning liq-uid content is correspondingly high, wastetransportation costs could increase. If thetotal solids content of the waste is expectedto vary, you can select equipment to accom-modate materials with a range of solids con-tent. For example, selecting spreaders thatwill not clog if the waste is slightly drier thanusual will help operations run more efficient-ly and reduce equipment problems.

B. pHA waste’s pH is a measure of its acidic or

alkaline quality. Most grasses and legumes, aswell as many shrubs and deciduous trees,grow best in soils with a pH range from 5.5to 7.5. If a waste is sufficiently acidic or alka-line5 to move soil pH out of that range, it canhamper plant growth. Acidic waste promotesleaching of metals, because most metals aremore soluble under acidic conditions thanneutral or alkaline conditions. Once in solu-tion, the metals would be available for plantuptake or could migrate to ground water.Alkaline conditions inhibit movement ofmost metals. Extreme alkalinity, where pH isgreater than 11, impairs growth of most soil

microorganisms and can increase the mobilityof zinc, cadmium, and lead.

Aqueous waste with a pH of 2 or less or apH of 12.5 or more meets the definition ofhazardous waste under federal regulations (40CFR 261.22(a)). If the pH of a waste makes ittoo acidic for land application, you can con-sider adjusting waste pH before application.Lime is often used to raise pH, but othermaterials are also available. The pH is alsoimportant to consider when developing wastehandling and storage procedures.

4 Some states consider composted materials to no longer be wastes. Consult with the regulatory agencyfor applicable definitions.

5 A pH of 7 is neutral. Materials with pH less than 7 are acidic, while those with pH greater than 7 arealkaline.

Source: Ag-Chem Equipment Co., Inc.Reprinted with permission

Source: Ag-Chem Equipment Co., Inc.

Reprinted with permission

Source: Ag-Chem Equipment Co., Inc.Reprinted with permission

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C. Biodegradable OrganicMatter

Wastes containing a relatively high percent-age of biodegradable organic matter havegreater potential as conditioners to improvethe physical properties of soil. The percentageof biodegradable organic matter in soil isimportant to soil fertility, as organic mattercan add nutrients; serve as an absorption andretention site for nutrients; and provide chem-ical compounds, such as chelating agents, thathelp change nutrients into more plant-avail-able forms. The content of biodegradableorganic matter is typically expressed as a per-centage of sample dry weight.

Biodegradable organic matter also influ-ences soil characteristics. Soils with highorganic matter content often have a darkercolor (ranging from brown to black), increasedcation exchange capacity—capacity to take upand give off positively charged ions—andgreater water holding capacity. Biodegradableorganic matter also can help stabilize andimprove the soil structure, decrease the densityof the material, and improve aeration in thesoil. In addition, organic nutrients are less like-ly than inorganic nutrients to leach.

How can biodegradable organic

matter affect the waste applica-tion rate?

While organic materials provide a signifi-cant source of nutrients for plant growth,decomposition rates can vary significantlyamong materials. Food processing residues, forexample, generally decompose faster thandenser organic materials, such as wood chips.It is important to account for the decomposi-tion rate when determining the volume, rateand frequency of waste application. Loadingthe soil with too much decomposing organicmatter (such as by applying new waste beforea previous application of slowly decomposing

waste has broken down) can induce nitrogendeficiency (see section D. below) or lead toanaerobic conditions.

D. NutrientsNitrogen, phosphorus, and potassium are

often referred to as primary or macro-nutri-ents and plants use them in large amounts.Plants use secondary nutrients, including sul-fur, magnesium, and calcium, in intermediatequantities. They use micronutrients, includ-ing iron, manganese, boron, chlorine, zinc,copper, and molybdenum, in very smallquantities. Land application is often used toincrease the supply of these nutrients, espe-cially the primary nutrients, in an effort toimprove plant growth.

Nutrient levels are key determinants ofapplication rates. Excessive soil nutrient lev-els, caused by high waste application rates,can be phytotoxic or result in contaminationof ground water, soil, and surface water.Nutrient loading is dependent on nutrientlevels in both the waste and the soil, makingcharacterization of the soil, as well as of thewaste, important.

Nitrogen. Nitrogen content is often theprimary factor determining whether a wasteis agriculturally suitable for land application,and, if so, at what rate to apply it. Nitrogendeficiency is detrimental to the most basicplant processes, as nitrogen is an essentialelement for photosynthesis. Sufficient nitro-gen promotes healthy growth and imparts adark green color in vegetation. Lack of nitro-gen can be identified by stunted plant growthand pale green or yellowish colored vegeta-tion. Extreme nitrogen deficiency can causeplants to turn brown and die. On the otherextreme, excessive nitrogen levels can resultin nitrate leaching, which can contaminateground-water supplies.


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6 U.S. Department of Agriculture, Agricultural Research Service. Agricultural Phosphorus andEutrophication, 1999. Washington, DC.

Although nitrate poses the greatest threatto ground water, nitrogen occurs in a varietyof forms including ammonium, nitrate,nitrite, and organic nitrogen. These formstaken together are measured as total nitrogen.You should account for the ever-occurringnitrogen transformations that take place inthe soil before and after waste is applied.These transformations are commonlydescribed as the nitrogen cycle and are illus-trated below in Figure 2.

Phosphorus. Phosphorus plays a role inthe metabolic processes and reproduction ofplants. When soil contains sufficient quanti-ties of phosphorus, root growth and plantmaturation improve. Conversely, phospho-rus-deficient soils can cause stunted plantgrowth. Excessive phosphorus can lead toinefficient use of other nutrients and, atextreme levels, zinc deficiency. High phos-phorus usage on crops and its associatedrunoff into surface water bodies has increasedthe biological productivity of surface watersby accelerating eutrophication, which is thenatural aging of lakes or streams brought onby nutrient enrichment.6 Eutrophication hasbeen identified as the main cause of impairedsurface water quality in the United States.

Potassium. Potassium is an essentialnutrient for protein synthesis and plays animportant role in plant hardiness and diseasetolerance. In its ionic form (K+), potassiumhelps to regulate the hydration of plants. Italso works in the ion transport system acrosscell membranes and activates many plantenzymes. Like other nutrients, symptoms ofdeficiencies include yellowing, burnt ordying leaves, as well as stunted plant growth.Symptoms of potassium deficiency also, in

certain plants, can includereduced disease resistance andwinter hardiness.

How can I take nutrient

levels into account?

You should develop a nutri-ent management plan thataccounts for the amount ofnitrogen, phosphorus, andpotassium being supplied by allsources at a site. The U.S.Department of Agriculture,Natural Resources ConservationService has developed a conser-vation practice standard

“Nutrient Management” Code 590 that canbe used as the basis for your nutrient man-agement plan. The purpose of this standardis to budget and supply nutrients for plantproduction, to properly utilize manure ororganic by-products as a plant nutrientsource, to minimize agricultural nonpointsource pollution of surface and ground-waterresources, and to maintain or improve thephysical, chemical, and biological conditionof the soil. Updated versions of this standardcan be obtained from the Internet at<www.nrcs.usda.gov/technical/ECS/nutrient/documents.html>.

Nitrogen is generally the most limitingnutrient in crop production systems and isadded to the soil environment in the greatest

Figure 2. The Nitrogen Cycle

GaseousLosses (N2, NOx)

Denitrification

Nitrates(NO3)

Leaching

Nitrification

PlantConsumption

Precipitation

Nitrites (NO2)

ClayMinerals

MicelleFixation

Ammonium (NH4)Nitrification

Mineralization

Organic Matter(R-NH2)

Organic Residues

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7 Nutrient Management Software: Proceedings from the Nutrient Management Software Workshop. Toorder, call NRAES at 607 255-7654 and request publication number NRAES-100.


amount of any of the plant nutrients. If, how-ever, waste application rates are based solelyon nitrogen levels, resulting levels of othernutrients such as phosphorus and potassiumcan exceed crop needs or threaten groundwater or surface water bodies. You shouldavoid excessive nutrient levels by monitoringwaste concentrations and soil buildup ofnutrients and reducing the application rate asnecessary, or by spacing applications to allowplant uptake between applications. Yourlocal, state, or regional agricultural extensionservice might have already developed materi-als on or identified software for nutrientmanagement planning. Consult with themabout the availability of such information.Northeast Regional Agricultural EngineeringServices (NRAES) Cooperative Extension, forexample, has compiled information on nutri-ent management software programs.7

E. MetalsA number of metals are included in IWEM

for evaluating ground-water risk. Some metals,such as zinc, copper, and manganese, areessential soil micronutrients for plant growth.These are often added to inorganic commercialfertilizers. At excessive concentrations, howev-er, some of these metals can be toxic tohumans, animals, and plants. High concentra-tions of copper, nickel, and zinc, for example,can cause phytotoxicity or inhibit plantgrowth. Also, the uptake and accumulation ofmetals in plants depends on a variety of plantand soil factors, including pH, biodegradableorganic matter content, and cation exchangecapacity. Therefore, it is important to evaluatelevels of these metals in waste, soil, and plantsfrom the standpoint of agricultural significanceas well as health and environmental risk.

How can I determine acceptable

metal concentrations?

The Tier I and II ground-water models canhelp you identify acceptable metals concentra-tions for land application. Also it is importantto consult with your local, state, or regionalagriculture extension center on appropriatenutrient concentrations for plant growth. If therisk evaluation indicates that a waste is appro-priate for land application, but subsequent soilor plant tissue testing finds excessive levels ofmetals, you can consider pretreating the wastewith a physical or chemical process, such aschemical precipitation to remove some metalsbefore application.

F. Carbon-to-Nitrogen RatioThe carbon-to-nitrogen ratio refers to the

relative quantities of these two elements in awaste or soil. Carbon is associated withorganic matter, and the carbon-to-nitrogenratio reflects the level of inorganic nitrogenavailable. Plants cannot use organic nitrogen,but they can absorb inorganic nitrogen suchas ammonium. For many wastes, the carbon-to-nitrogen ratio is computed as the dryweight content of organic carbon divided bythe total nitrogen content of waste.

Some wastes rich in organic materials (car-bon) can actually induce nitrogen deficien-cies. This occurs when wastes provide carbonin quantities that microbes cannot processwithout depleting available nitrogen. Soilmicrobes use carbon to build cells and nitro-gen to synthesize proteins. Any excess organ-ic nitrogen is then converted to inorganicnitrogen, which plants can use. The carbon-to-nitrogen ratio tells whether excess organicnitrogen will be available for this conversion.

When the carbon-to-nitrogen ratio is lessthan 20 to 1—indicating a high nitrogen con-tent—organic nitrogen is mineralized, or con-


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verted from organic nitrogen to inorganicammonium, and becomes available for plantgrowth. For maximal plant growth, the litera-ture recommends maintaining a ratio below20 to 1. When the carbon-to-nitrogen ratio isin the range of 20 to 1 to 30 to 1—a lownitrogen content—soil micro-organisms usemuch of the organic nitrogen to synthesizeproteins, leaving only small excess amountsto be mineralized. This phenomenon, knownas immobilization, leaves little inorganicnitrogen available for plant uptake. When thecarbon-to-nitrogen ratio is greater than 30 to1, immobilization is the dominant process,causing stunted plant growth. The period ofimmobilization, also known as nitrogen ornitrate depression, will vary in lengthdepending on the decay rate of the organicmatter in the waste. As a result, plant growthwithin that range might not be stunted, but isnot likely to be maximized.

How can I manage changing

carbon-to-nitrogen ratios?

The cycle of nitrogen conversions withinthe soil is a complex, continually changingprocess (see Figure 2). As a result, if applyingwaste based only on assumed nitrogen miner-alization rates, it is often difficult to ensurethat the soil contains sufficient inorganicnitrogen for plants at appropriate times. Ifyou are concerned about reductions in cropyield, you should monitor the soil’s carbon-to-nitrogen ratio and, when it exceeds 20 to1, reduce organic waste application and/orsupplement the naturally mineralized nitro-gen with an inorganic nitrogen fertilizer, suchas ammonium nitrate. Methods to measuresoil carbon include EPA Method 9060 in TestMethods for Evaluating Solid Waste,Physical/Chemical Methods—SW-846. Nitrogencontent can be measured with simple labora-tory titrations.

G. Soluble SaltsThe term soluble salts refers to the inorganic

soil constituents (ions) that are dissolved in thesoil water. Major soluble salt ions include calci-um (Ca2+), magnesium (Mg2+), sodium (Na+),potassium (K+), chloride (Cl-), sulfate (SO4

2-),bicarbonate (HCO3

-), and nitrate (NO3-). Total

dissolved solids (TDS) refers to the totalamount of all minerals, organic matter, andnutrients that are dissolved in water. The solu-ble salt content of a material can be determinedby analyzing the concentration of the individ-ual constituent ions and summing them, butthis is a lengthy procedure. TDS of soil orwaste can reasonably be estimated by measur-ing the electrical conductivity (EC) of a mixtureof the material and water. EC can be measureddirectly on liquid samples. TDS is found bymultiplying the electrical conductivity readingin millimhos/cm (mmhos/cm) by 700 to giveTDS in parts per million (ppm) or mg/l.

Soluble salts are important for several rea-sons. First, saline soil, or soil with excessivesalt concentrations, can reduce plant growthand seed germination. As salt concentrationin soil increases, osmotic pressure effectsmake it increasingly difficult for plant roots toextract water from the soil. Through a certainrange, this will result in reduced crop yield,up to a maximum beyond which crops willbe unable to grow. The range and maximumfor a few representative crops are shown inTable 2. For this reason, the salt content ofthe waste, rather than its nitrogen content,can be the primary determinant of its agricul-tural suitability for land application, especial-ly on irrigated soils in arid regions.

The second reason soluble salts are impor-tant is that sodic soil, or soil with excessivelevels of sodium ions (Na+) relative to diva-lent ions (Ca2+, Mg2+), can alter soil structureand reduce soil permeability. The sodiumabsorption rate (SAR) of a waste is an indica-tor of its sodicity. To calculate the SAR of a

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waste or soil, determine the Na+, Ca2+, andMg2+ concentrations in milliequivalents perliter8 for use in the following equation:9

Soils characterized by both high salts(excessive TDS as indicated by EC) andexcessive sodium ions (excessive Na+ as indi-cated by SAR) are called saline-sodic soils,and can be expected to have the negativecharacteristics of both saline soils and sodicsoils described above. Table 3 displays ECand SAR levels indicative of saline, sodic, andsaline-sodic soils.

The third reason soluble salts are impor-tant is that specific ions can induce plant tox-icities or contaminate ground water. Sodiumand chloride ions, for example, can becomephytotoxic at high concentrations. To assesssodic- or toxic-inducing characteristics, youshould conduct an analysis of specific ions inaddition to measuring EC.

What can I do if a waste is either

saline or sodic?

Saline waste. If a waste is saline, carefulattention to soil texture, plant selection, andapplication rate and timing can help. Coarsesoils often have a lower clay content and areless subject to sodium-induced soil structure

8 The term milliequivalents per liter (meq/l) expresses the concentration of a dissolved substance interms of its combining weight. Milliequivalents are calculated for elemental ions such as Na+, Ca2+, andMg2+ by multiplying the concentration in mg/l by the valence number (1 for Na+, 2 for Ca2+ or Mg2+)and dividing by the atomic weight (22.99 for Na+, 40.08 for Ca2+, or 24.31 for Mg2+).

9 If the proper equipment to measure these concentrations is not available, consider sending soil andwaste samples to a soil testing laboratory, such as that of the local extension service (visit <www.reeus-da.gov/statepartners/usa.htm> for contact information) or nearby university. Such a laboratory will beable to perform the necessary tests and calculate the SAR.

Source: Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.

a A rule of thumb from the irrigation industry holds that soil salinity will be 1½ times the salinity of applied

irrigation water. The effect that waste salinity will have on soil salinity, however, is not as easily predicted

and depends on the waste’s water content and other properties and on the application rate.

b Reductions are stated as a percentage of maximum expected yield.

Soi l Sal ini ty (mmhos/cm) a that wi l l result in :

Crop 0% yield 50% yield 100% yieldreductionb reductionb reductionb

Alfalfa 2.0 8.8 16

Bermuda grass 6.9 14.7 23

Clover 1.5 10.3 19

Perennial rye 5.6 12.1 19

Tall fescue 3.9 13.3 32

Table 2:

Salinity Tolerance of Selected Crops

SAR =Na+

½(Ca2+ + Mg2+)

problems. While coarse soils help minimizesoil structural problems associated with salin-ity, they also have higher infiltration and per-meability rates, which allow for more rapidpercolation or flushing of the root zone. Thiscan increase the risk of waste constituentsbeing transported to ground water.

Since plants vary in their tolerance tosaline environments, plant selection also isimportant. Some plant species, such as ryegrass, canary grass, and bromegrass, are onlymoderately tolerant and exhibit decreasedgrowth and yields as salinity increases. Otherplants, such as barley and bermuda grass, aremore saline-tolerant species.

You should avoid applying high salt con-tent waste as much as possible. For salinewastes, a lower application rate, and thor-ough tilling or plowing can help dilute theoverall salt content of the waste by mixing itwith a greater soil volume. To avoid theinhibited germination associated with salinesoils, it also can help to time applications ofhigh-salt wastes well in advance of seedings.

Sodic waste. SAR alone will not tell howsodium in a waste will affect soil permeability;it is important to investigate the EC of a wasteas well. Even if a waste has a high SAR, plantsmight be able to tolerate this level if the wastealso has an elevated EC. As with saline waste,for sodic waste select a coarser-textured soil tohelp address sodium concerns. Adding gyp-

sum (CaSO4) to irrigation water can also helpto reduce the SAR, by increasing soil calciumlevels. Although this might help address sodi-um-induced soil structure problems, if choos-ing to add constituents to alter the SAR, theEC should also be monitored to ensure salini-ty levels are not increased too much.

H. Calcium CarbonateEquivalent

Calcium carbonate equivalent (CCE) isused to measure a waste’s ability to neutralizesoil acidity—its buffering capacity—as com-pared with pure calcium carbonate. Bufferingcapacity refers to how much the pH changeswhen a strong acid or base is added to a solu-tion. A highly buffered solution will showonly a slight change in pH when strong acidsor bases are added. Conversely, if a solutionhas a low buffering capacity, its pH willchange rapidly when a base or acid is addedto it. If a waste has a 50 percent CCE, itwould need to be applied at twice the rate ofpure calcium carbonate to achieve the samebuffering effect.

I. PathogensPotential disease-causing microorganisms

or pathogens, such as bacteria, viruses, proto-zoa, and the eggs of parasitic worms, mightbe present in certain wastes. Standardized


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Source: Fipps, G. Managing Irrigation Water Salinity In the Lower Rio Grande Valley.aIn units of mmhos/cm bdimensionless

Soi l Character izat ion

Normal Saline Sodic Saline-Sodic

ECa < 4 and EC > 4 SAR> 13 EC > 4 and

SARb < 13 SAR > 13

Table 3EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils

testing procedures are available to help deter-mine whether a waste contains pathogens.You should consider using such tests espe-cially if your process knowledge indicatesthat a waste might contain pathogens. Fecalcoliform bacteria can be quantified, for exam-ple, by using a membrane filtering technique,which involves passing liquid waste througha filter, incubating the filtrate (which containsthe bacteria) on a culture medium for 24hours, and then counting the number of bac-terial colonies formed.

How can I reduce pathogenic

risks?

Methods to reduce pathogenic risk includedisinfecting or stabilizing a waste prior toland application. Examples of treatmentmethods recognized for sewage sludgestabilization are included in the sidebar.Pathogens present a public health hazard ifthey are transferred to food or feed crops,contained in runoff to surface waters, ortransported away from a land application siteby vectors. If pathogen-carrying vectors are aconcern at a site, it is important to establishmeasures to control them. For examples ofmethods to control vectors, refer to Chapter8–Operating the Waste Management System.Additional information on pathogen reduc-tion and methods to control vectors can beobtained from 40 CFR 503.15 and 40 CFR503.32 (EPA’s Sewage Sludge Rule.) A dis-cussion of these alternatives is available inEPA’s guidance document Land Application ofSewage Sludge: A Guide for Land Appliers onthe Requirements of the Federal Standards forthe Use or Disposal of Sewage Sludge, 40 CFRPart 503 (U.S. EPA, 1994a).

The services of a qualified engineer mightbe necessary to design an appropriate processfor reducing pathogens in a waste. Youshould consult with the state to determinewhether there are any state-specific require-

ments for pathogen reductions for specificwaste types.

III. Measuring SoilProperties

Physical, biological, and chemical charac-teristics of the soil are key factors in deter-mining its capacity for waste attenuation. Ifthe soil is overloaded, rapid oxygen deple-tion, extended anaerobic conditions, and theaccumulation of odorous and phytotoxicend-products can impair soil productivityand negatively impact adjacent properties.With proper design and operation, waste canbe successfully applied to almost any soil;however, sites with highly permeable soil(e.g., sand), highly impermeable soil (e.g.,clay), poorly drained soils, or steep slopescan present special design issues. Therefore,it is advisable to give such sites lower priorityduring the site selection process.

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What are methods for stabilizingwaste prior to land application?

The following methods, recommendedfor stabilizing sewage sludge, can also beuseful for reducing pathogens in waste:

• Aerobic digestion

• Air drying

• Anaerobic digestion

• Composting

• Lime stabilization

More detailed information on each ofthese and other methods can be foundin EPA’s Control of Pathogens and VectorAttraction in Sewage Sludge (U.S. EPA,1992).

How can I evaluate the soil at a

site?

To help evaluate the soil properties of asite, you should consult the U.S. Departmentof Agriculture (USDA) soil survey for theprospective area. These surveys provide infor-mation on properties such as soil type andpermeability. USDA has prepared soil surveysfor most counties in each state. To obtain acopy of the survey for an area, contact theNatural Resource Conservation Service offices,the county conservation district, the state agri-cultural cooperative extension service, or localhealth authorities/planning agency. These soilssurveys will help during site selection; howev-er, conditions they describe can differ fromthe actual soil conditions.

Several guidance documents on soil sur-veys are also available from USDA. Thesedocuments include the National Soil SurveyHandbook and the guide Soil Taxonomy: ABasic System of Soil Classification for Makingand Interpreting Soil Surveys. The National SoilSurvey Handbook provides an abundance ofinformation including help on interpretingsoil surveys, a primer on soil properties andsoil quality, and guides for predicting the per-meability of your soil. Both of these docu-ments are available over the Internet and canbe obtained from <www.ftw.nrcs.usda.gov/tech_ref.html>.

For more site-specific data on actual soilconditions, you can sample and characterizethe soil. It might be desirable to have a quali-fied soil scientist perform this characteriza-tion, which often includes soil texture,percentage of organic matter, depth to watertable, soil pH, and cation exchange capacity.At a minimum, you should characterize sam-ples from an upper soil layer, 0 to 6 inches,and a deeper soil layer, 18 to 30 inches, andfollow established soil sampling procedures toobtain meaningful results. If a detailed charac-terization is desired, or if it is suspected soil

types vary considerably, further subdivision ofsoil horizons or collection of samples over agreater variety of depths might be appropriate.For more information about how to obtainrepresentative soil samples and to submitthem for analysis, you can consult EPA’sLaboratory Methods for Soil and Foliar Analysisin Long-Term Environmental MonitoringPrograms (U.S. EPA, 1995d), or state guides,such as Nebraska’s Guidelines for Soil Sampling,G91-1000.

Why are chemical and biological

properties of soil important?

Chemical and biological properties of thesoil, like those of the waste, influence theattenuation of waste constituents. Theseproperties include pH, percentage of organicmatter, and cation exchange capacity. Affectedattenuation processes in the soil includeabsorption, adsorption, microbial degrada-tion, biological uptake, and chemical precipi-tation. For example, adsorption—the processby which molecules adhere to the surface ofother particles, such as clay—increases as thecation exchange capacity and pH of the soilincrease. Cation exchange capacity, in turn, isdependent on soil composition, increasing asthe clay content of the soil increases.Adsorption through cation exchange is animportant means of immobilizing metals inthe soil. Organic chemicals, on the otherhand, are negatively charged and can beadsorbed through anion exchange, or theexchange of negative ions. A soil’s capacity foranion exchange increases as its pH decreases.

Why are physical properties of

soil important?

Physical properties of the soil such as tex-ture, structure, and pore-size distribution affectinfiltration rates and the ability of soil to filteror entrap waste constituents. Infiltration andpermeability rates decrease as clay content


7C-13

increases. Sites with soils with permeabilitiesthat are too high or too low have lower landapplication potential. Soils with high perme-ability can allow wastes to move through with-out adequate attenuation. Soils with lowpermeability can cause pooling or excessivesurface runoff during intense rainstorms.Excessive runoff conditions can be compensat-ed for somewhat by minimizing surface slopeduring site selection. Soils with low perme-ability are also prone to hydraulic overloading.

The amount of liquid that can be assimi-lated by a soil system is referred to as itshydraulic loading capacity. In addition to asoil’s permeability, hydraulic loading capacityis dependent on other factors such as cli-mate, vegetation, site characteristics, andother site-specific soil properties such as soiltype, depth to seasonally high water table,slope and erodibility, water intake rate, andunderlying geology and hydrogeology.Exceeding the hydraulic loading capacity of asite, can lead to rapid leaching of waste con-stituents into ground water, reduction in bio-logical activity, sustained anaerobicconditions, soil erosion, and possible conta-mination of surface waters. It can also resultin excessive evaporation, which can causeexcessive odor and unwanted airborne emis-sions. In order to avoid hydraulic overload-ing at a site, application of liquid orsemi-liquid waste or wastewater should bemanaged so uncontrolled runoff or prolongedsaturation of the soil does not occur.

An important indicator of soil properties isits topography, which affects the potential forsoil erosion and contaminated surface-waterrunoff. Soils on ridge tops and steep slopesare typically well drained, well aerated, andshallow. Steep slopes, however, increase thelikelihood of surface runoff of waste and ofsoil erosion into surface waters. State guide-lines, therefore, often specify the maximumslopes allowable for land application sites forvarious waste characteristics, application

techniques, and application rates. The agen-cies that regulate land application in a statecan provide specific guidance concerningslopes. Soils on concave land and broad flatlands, on the other hand, frequently arepoorly drained and can be waterlogged dur-ing part of the year. Soils in relatively flatareas can have intermediate properties withrespect to drainage and runoff and could bemore suitable for land application.

IV. Studying theInteraction ofPlants andMicrobes withWaste

The next step in the design of a landapplication unit is to consider the plants andmicrobes at the site and how they will inter-act with the waste. This interaction includesthe uptake and degradation of waste con-stituents, the effects of the wastes on plantand microbial growth, and changes that canoccur in plants or crops affecting their use asfood or feed. The uptake of nutrients byplants and microbes on plant roots or in soilaffects the rate of waste assimilation andbiodegradation, usually increasing it.

It might be necessary to conduct green-house or field studies or other tests of plants,soil, and microbes to understand and quanti-fy these interactions. You should consult withthe state agricultural department, the localhealth department, and other appropriateagencies if considering land application ofwastes containing designated ground-waterconstituents or other properties that arepotentially harmful to food or feed crops.Industry groups might also be able to pro-vide information about plants with whichthey have land application experience.

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A. Greenhouse and FieldStudies

State agricultural extension services, depart-ments of environmental protection, or publicuniversities might have previous studies aboutplant uptake of nutrients, especially nitrogen,phosphorus, and potassium, but it is impor-tant to recognize that the results of studiesconducted under different conditions (such asdifferent waste type, application rate, planttype, or climate) are only partially relevant to aspecific situation. Furthermore, most studies todate have focused on relatively few plantspecies, such as corn, and only a handful ofconstituents, typically metals. Greenhousestudies or pilot-scale field studies attempt tomodel site-specific conditions by growing theintended crops in soil from the prospectiveapplication site. These studies are usefulbecause individual parameters can be varied,such as plant type and waste application rate,to determine the effects of each factor.Additionally, greenhouse or field studies mightbe required by some states to certify that awaste has agricultural benefits. Generally, thefirst point of contact for assistance with studiesis the state agricultural extension service. Manystate extensions can conduct these studies;others might be able to provide guidance orexpertise but will recommend engaging a pri-vate consultant to conduct the studies.

How do I conduct greenhouse or

field studies?

Currently, no national guidelines exist forconducting greenhouse or field studies,10 butcheck to see if the state has guidance onaccepted practices. Working with a state agri-cultural extension service or a local universitywill provide the benefit of their expertise andexperience with local conditions, such aswhich plants are suitable for local soils andclimate. If a particular industry sector has alarge presence in a state, the state agricultural

extension service might have previous experi-ence with that specific type of waste.

Greenhouse studies. Aside from theirsmaller scale, greenhouse studies differ fromfield studies primarily in that they are con-ducted indoors under controlled conditions,while field studies are conducted under nat-ural environmental conditions. A greenhousestudy typically involves distributing represen-tative soil samples from the site into severalpots to test different application rates, appli-cation methods, and crops. Using severalduplicate pots for each rate, method, or cropallows averaging and statistical aggregating ofresults. It is also important to establish con-trol pots, some with no waste and no plants,others with waste but no plants (to observethe extent to which waste assimilation effectsare due to soil and pre-existing microbes) andstill others with plants but without waste (asa baseline for comparison with waste-amend-ed plant growth).

To theextentfeasible,tempera-ture,mois-ture, andotherparame-ters should simulate actual site conditions.There should be a series of several duplicatepots grown with each combination of planttype, application rate, and other parameters.Pots should be arranged to avoid environ-mental conditions disproportionately affectingone series of pots. For example, you shouldavoid placing a whole series of pots in a rowclosest to a light source; instead, it is better toplace one pot from each of several series inthat row or randomize placement of pots.

The controlled greenhouse environmentallows the study of a wide range of waste-soil


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10 Based on conversations with Dr. Rufus L. Chaney and Patricia Milner, U.S. Department of Agriculture.

interactions without risking the loss of plantsdue to weather, animal hazards, and otherenvironmental influences. At the same time,this can introduce differences from actualconditions. Root confinement, elevated soiltemperature, and rapidly changing moisturelevels, for example, can increase the uptakeof pollutants by potted plants compared touptake under field conditions.11

Field studies. Field studies, on the otherhand, can test application rates and crops onplots at the actual proposed site. As withgreenhouse studies, duplicate plots are usefulfor statistical purposes, and controls areneeded. Field study data can be more usefulbecause it more closely reflects real-worldconditions, but it also can be more difficultto obtain because of uncontrollable circum-stances such as flooding or unusual pestdamage that can occur at the time of thestudy. Field studies also can be subject to sit-ing, health and safety, and permittingrequirements.

Field studies also help determine the actu-al land area required for land application andthe quality of runoff generated. Soil andground-water monitoring help to confirmthat waste constituents are being taken up byplants and not leaching into the groundwater. Results from field studies, however,might not be duplicated on actual workingplots after multiple waste applications, due tolong-term soil changes. Crop yields also canvary by as much as 15 to 25 percent under

field conditions, even with good fertility andmanagement.

Both greenhouse and field studies typicallyinclude extensive sampling of waste, soilbefore application, plants or representativeparts of plants, soil after application, growthof plants, and, to the extent feasible, water.You should sample soil at the surface and inlower horizons using core sampling. Somesoil tests require mixing samples with waterto form a paste or slurry. Plant tissue testsoften require dry-weight samples, made bydrying cut plants at about 65°C. Water canbe collected in lysimeters (buried chambersmade from wide perforated pipe) andremoved using hand pumps.

The effects of waste on organisms in thesoil can also be monitored during greenhouseand field studies. The literature suggests, thatthe effects of waste on earthworms are a goodindicator of effects on soil organisms in gen-eral. It might be worthwhile, therefore, tostock greenhouse pots or field study plotswith earthworms at the beginning of a studyand monitor the waste constituent levels andthe effects on the worms during and at theend of the study. Although these brief studieswill not effectively model long-term exposureto waste constituents, it is possible to gaugeshort-term and acute effects.

B. Assessing Plant andMicrobial Uptake Rates

Plants. After performing studies, youshould measure the amounts of variousnutrients, metals, and other constituents intissue samples from plants grown in thegreenhouses or on test plots. This tellsapproximately how much of these con-stituents the plants extracted from the soil-waste mix. By measuring plant-extractedquantities under these various conditions,you can determine a relationship between

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11 If a waste contains VOCs, ensure the possibility of VOCs accumulating within the enclosed greenhouseis addressed.


plant type, application rate, and nutrientextraction. From this, you can choose theconditions which result in the desired uptakerate while avoiding uptake of designatedground-water constituents at undesirableconcentrations. Plant uptake is often mea-sured as a ratio of the pollutant load found inthe plants to the pollutant load applied to theland as illustrated below:

This ratio serves to place pollutant uptakein the context of the original amount of pol-lutant applied.

In choosing plants for a land applicationunit, you should also consider growing seasonsin relation to periods of waste application rate.Specific waste application rates associated withcorresponding uptakes of nutrients by plants,as indicated in greenhouse or field studies, areapplicable only during the growing phases cov-ered by the study. At other times, waste appli-cation might be infeasible because plants arenot present to help assimilate waste, or becauseplants are too large to permit passage of appli-cation equipment without sustaining damage.

Microbes. Certain microbes can biode-grade organic chemicals and other waste con-stituents. Some accomplish this by directlyusing the constituents as a source of carbonand energy, while others co-metabolize con-

stituents in the process of using other com-pounds as an energy source. Aerobic microor-ganisms require oxygen to metabolize wasteand produce carbon dioxide and water as endproducts. Anaerobic microbes function with-out oxygen but produce methane and hydro-gen sulfide as end products. These gases canpresent a safety risk as well as environmentalthreats, and hydrogen sulfide is malodorous.For these reasons, it is recommended thatyou maintain conditions that favor aerobicmicrobes.

For many microorganisms, these condi-tions include a pH of 6 to 8 and temperaturesof 10°C to 30°C. In addition, microbes mightbe unable to transfer oxygen from soil effi-ciently if the moisture content is near satura-tion, or they might be unable to obtainsufficient water if the soil is too dry. A watercontent of 25 to 85 percent of the soil’s waterholding capacity is recommended in the liter-ature. Oxygen generally is available throughdiffusion from the atmosphere, but thismechanism might provide insufficient oxygenif there is too little pore space (less than 10percent of soil volume) or if so much organicmatter is applied that oxygen is consumedfaster than it is replaced.

C. Effects of Waste onPlant and MicrobeGrowth

Greenhouse and field studies can tell whateffect the waste will have on plant growth pat-terns. A typical method of quantifying plantgrowth is to state it in terms of biomass pro-duction, which is the dry weight of the cutplants (or representative parts of the plants). Ifthe plants grown with waste applicationsshow greater mass than the control plants,12

the waste might be providing useful nutrientsor otherwise improving the soil. If the plantsgrown with waste applied at a certain rate


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12 Trends detected in studies assume that results have been subjected to tests of statistical validity beforefinding a trend significant.

µg pollutantper

g dry plant tissue

kg pollutant

hectare

weigh less than the controls, some con-stituent(s) in the waste might be excessive atthe studied application rate. Comparing theresults from several different application ratescan help find the rate that maximizes growthand avoids detrimental and phytotoxic effects.

Analyzing soil and water after plant growthallows for a comparison between the plantedpots or plots against the control to discern thedifferences due to plant action. If water sam-ples show excessive nutrient (especially nitro-gen) levels at a certain application rate, thismight indicate that the plants were unable touse all the nutrients in the waste applied atthat rate, suggesting that the application wasexcessive. If soil and water tests show thatconstituents are consumed, and if other possi-ble causes can be ruled out, microbes mightbe responsible. Further investigation ofmicrobial action might involve sampling ofmicrobes in soil, counting their population,and direct measurement of waste constituentsand degradation byproducts.

D. Grazing and HarvestingRestrictions

If a waste might contain pathogens or des-ignated ground-water constituents, and theestablished vegetative cover on the landapplication site is intended for animal con-sumption, it is important to take precautionsto minimize exposure of animals to thesecontaminants. This is important because ani-mals can transport pathogens and ground-water constituents from one site to another,and can be a point of entry for waste con-stituents and pathogens into the food chain.

If harvesting crops from a unit for use asanimal fodder, you should test plants for thepresence of undesirable levels of the desig-nated ground-water constituents before feed-ing. Grazing animals directly on a unit isdiscouraged by some states.13 If consideringdirect grazing, you should consult with the

state to see if there are any restrictions onthis practice. Growing crops for human con-sumption on soil amended with waste callsfor even greater caution. In some states, thispractice is prohibited or regulated, and instates where it is allowed, finding foodprocessors or distributors willing to purchasesuch crops can be difficult.

When testing crops before feeding themto animals, local agricultural extension ser-vices might be able to help determine whatlevels are appropriate for animal consump-tion. If plant tissue samples or findings of afate and transport model indicate waste con-stituent levels inappropriate for animal con-sumption, it is important that you not useharvested plants as fodder or allow grazingon the site. Additionally, plants with highconstituent levels will probably be inappro-priate for other agricultural use, and thuswould likely necessitate disposal of suchcrops as a waste after harvest.

V. ConsideringDirect Exposure,EcosystemImpacts, &Bioaccumulationof Waste

You should evaluate the impacts that yourland application unit will have on directexposure and ecological pathways as well asthe potential for bioaccumulation of land-applied waste. During the land applicationunit’s active life, direct human exposure towaste or waste-amended soil is primarily arisk to personnel involved in the operation.You should follow OSHA standards andensure that personnel are properly trainedand use proper protective clothing and equip-

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13 Grazing can also be unwise due to potential effects on soil physical structure. The weight of heavy ani-mals can compact soil, decreasing pore space, which can reduce the soil’s waste attenuation capacity.


ment when working onsite. You should limitdirect exposure to others through steps suchas access control and vehicle washing to pre-vent tracking waste and waste amended soiloff site.

Access control will also limit exposure ofsome animals. If crops will be used for animalfodder or grazing, you should test harvestedfodder for the designated ground-water con-stituents before use and restrict grazing times.After a site is closed, there might be long-termaccess risks to future land uses and the gener-al public. To minimize these risks, long-termaccess controls or deed restrictions might beappropriate. Consult Chapter 11—PerformingClosure and Post-Closure Care for furtherinformation.

Direct exposure of native animals is oftenimpossible to control and might be an entrypoint for the ground-water constituents intothe food chain. Worms, for example, mightbe present in the soil and take in these con-stituents. Birds or other animals could thenconsume the worms, bioaccumulate, or betransported off site. Furthermore, animals caningest plants grown on waste-amended soil.Therefore, you should also consider pathwayssuch as these in evaluating your plans forland application.

VI. Accounting forClimate

Local climate considerations should alsoenter into your land application planningprocess. For example, wastes that are high insoluble salts are less appropriate and can havedeleterious effects in arid climates due to theosmotic pressure from the salts inhibiting rootuptake of water. On the other hand, the down-ward movement of water in the soil is minimalin arid climates, making the migration of wasteconstituents to ground water less likely.

Climate also determines which plants cangrow in a region and the length of the grow-ing season. If the local climate cannot sup-port the plants that might be most helpful inassimilating the particular constituents in agiven waste, the use of land application mightbe limited to other crops at a lower applica-tion rate. If the climate dictates that the partof the growing cycle during which land appli-cation is appropriate is short, a larger area forland application might be necessary.

There are also operating considerationsassociated with climate. Since waste shouldnot be applied to frozen or very wet soil, theapplication times can be limited in cold orrainy climates. In climates where the groundcan freeze, winter application poses particularproblems even when the ground is not frozen,because if the ground freezes soon after appli-cation, the waste that remained near the soilsurface can run off into surface waters duringsubsequent thaw periods. Waste nutrients arealso more likely to leach through the soil andinto the ground water following spring thaw,prior to crop growth and nutrient uptake.These problems can be partially solved byproviding sufficient waste storage capacity forperiods of freezing or rainy weather.

VII. Calculating AnAgronomicApplication Rate

The purpose of a land application unit(i.e., waste disposal versus beneficial use)helps determine the waste application ratebest suited for that unit. When agriculturalbenefits are to be maximized, the applicationrate is governed by the agronomic rate. Theobjective for determining an agronomic appli-cation rate is to match, as closely as possible,the amount of available nutrients in the wastewith the amount required by the crop. One


7C-19

example of an equation for calculating agro-nomic application rates is:

Agronomic application rate = (Crop nutri-ent uptake × Crop yield)-Nutrient credits

Where:

Crop nutrient uptake = Amount of nutri-ents absorbed by a particular crop. Theserequirements are readily available fromyour state and local Cooperative ExtensionOffices

Crop yield = Amount of plant available forharvest. Methods for calculating expectedyields include past crop yields for thatunit, county yield records, soil productivi-ty tables, or local research.

Nutrient credits = Nitrogen residual frompast waste applications, irrigation waternitrate nitrogen, nutrients from commer-cial fertilizer, and other nitrogen creditsfrom atmospheric deposition from dustand ammonia in rainwater.

In addition, many states and universitieshave developed their own worksheets or cal-culations for developing an agronomic appli-cation rate. You should check with your stateagency to see if you are subject to an existingregulation. In setting a preliminary applica-tion rate the crop’s nitrogen requirementsoften serve as a ceiling, but in some cases,phosphorus, potassium, or salt content, ratherthan nitrogen, will be the limiting factor.

How do I determine the agro-

nomic rate?

Computer models can help determine site-specific agronomic rates. Modeling nitrogenlevels in waste and soil-plant systems can helpprovide information about physical andhydrologic conditions and about climaticinfluences on nitrogen transformations.Models recommended for use with sewagesludge include Nitrogen Leaching andEconomic Analysis Package (NLEAP);DECOMPOSITION; Chemicals, Run-Off, andErosion from Agricultural ManagementSystems (CREAMS); and Ground-WaterLoading Effects of Agricultural ManagementSystems (GLEAMS).14 NLEAP is a moderatelycomplex, field scale model that assesses thepotential for nitrate leaching under agricultur-al fields. NLEAP can be used to comparenitrate leaching potential under different soilsand climates, different cropping systems, anddifferent management scenarios. The comput-er model DECOMPOSITION is specificallydesigned to help predict sewage sludge nitro-gen transformations based on sludge charac-teristics, as well as climate and soil properties(organic matter content, mean soil tempera-ture, and water potential). Finally, theCREAMS and GLEAMS models, developed bythe USDA, are other potentially useful modelsto assist with site-specific management of landapplication operations. Additional computermodels include Cornell Nutrient ManagementPlanning System (NMPS), Fertrec Plus v 2.1,and Michigan State University Nutrient

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14 All of these models are referenced in EPA’s Process Design Manual: Land Application of Sewage Sludge andDomestic Septage (U.S. EPA, 1995b). According to that source, the NLEAP software, developed byShaffer et al., is included in the purchase of Managing Nitrogen for Groundwater Quality and FarmProfitability by Follet, et al., which also serves as reference for information on parameters required fornitrogen calculations. Four regional soil and climatic databases (Upper Midwest, Southern,Northeastern, and Western) also are available on disk for use with NLEAP. These materials can beobtained from: Soil Science Society of America Attn: Book Order Department, 677 S. Segoe Road,Madison, WI 53711, 608/273-2021; Book $36.00; Regional Databases $10.00 each. Current updates ofthe NLEAP program can be obtained by sending original diskettes to: Mary Brodahl, USDA-ARS-GPSR,Box E, Fort Collins, CO 80522. Additional information on the DECOMPOSITION model, developedby Gilmour and Clark, can be obtained from: Mark D. Clark, Predictive Modeling, P.O. Box 610,Fayetteville, AR 72702. The CREAMS and GLEAMS models were developed by USDA.


Management v1.1.15 If assistance is required indetermining an appropriate agronomic rate fora waste, you should contact the regional, state,or county agricultural cooperative extensions,or a similar organization.

VIII. MonitoringMonitoring ground water can be helpful to

verify whether waste constituents have migrat-ed to ground water. Some state, tribal, orother regulatory authorities require ground-water monitoring at certain types of landapplication units; you should consult with theappropriate regulatory agency to determinewhether such a requirement applies to theunit. Even if the unit is not required to moni-tor ground water, instituting a ground-watermonitoring program is recommended forlong-term, multiple application units wherewastes contain the designated ground-waterconstituents. Such units are more likely topose a threat to ground water than are single-application units or units receiving wastewithout these constituents.

In most cases, lysimeters should be suffi-cient to monitor ground water. A lysimeter isa contained unit of soil, often a box or cylin-der in the ground which is filled with soil,open on the top, and closed at the bottom, sothat the water that runs through it can be col-lected. It is usually more simple and econom-ical to construct and operate than amonitoring well. You can consult with a qual-ified professional to develop an appropriateground-water monitoring program for yourland application unit.

If ground-water results indicate unaccept-able constituent levels, you should suspendland application until the cause is identified.You should then correct the situation that ledto the high readings. If a long-term change inthe industrial process, rather than a one-timeincident, caused the elevated levels, you

should reevaluate your use of land applica-tion. Adjusting the application rate, addingpretreatment, or switching to another meansof waste management might be necessary.After reevaluation, you should examinewhether corrective action might be necessaryto remediate the contaminated ground water.You should pay particular attention to ensurethat applications are not exceeding the soil’sassimilative capacity.

You should also consider testing soil sam-ples periodically during the active life of aland application unit. For this testing to bemeaningful, it is important that you firstdetermine baseline conditions by samplingthe soil before waste application begins. Thismight already have been done in preparationfor greenhouse/field studies or for site charac-terization. Later, when applying waste to theunit, you should collect and analyze samplesat regular intervals (such as annually or aftera certain number of applications). Consideranalyzing samples for macronutrients,micronutrients, and any of the designatedground-water constituents reasonably expect-ed to be present in the waste. The locationand number of sampling points, frequency ofsampling, and constituents to be analyzedwill depend on site-specific soil, water, plant,and waste characteristics. Local agriculturalextension services, which have experiencewith monitoring, especially when coupledwith ground-water monitoring, can detectcontamination problems. Early detectionallows time to change processes to remedythe problems, and to conduct correctiveaction if necessary before contaminationbecomes widespread.

Testing soils after the active life of a unitends might also be appropriate, especially ifthe waste is likely to have left residues in thesoil. The duration of monitoring after closure,like the location and frequency of monitoringduring active life, is site-specific and dependson similar factors. For further information


7C-21

15 These models are referenced in the Northeast Regional Agricultural Engineering CooperativeExtension’s Nutrient Management Software: Proceedings from the Nutrient Management SoftwareWorkshop from December 11, 1996.

about testing soil after the active life of a unitends, refer to Chapte 11—PerformingClosure and Post-Closure Care.

IX. Odor ControlsOdors are sometimes a common problem

at land application facilities and an odormanagement plan can allow facility managersto respond quickly and effectively to dealwith odor complaints. A plan should involveworking to prevent odors from occurring,working with neighbors to resolve odor com-plaints, and making changes if odors becomean unacceptable condition. The plan shouldalso identify the chemical odor constituents,determine the best method for monitoringodor, and develop acceptable odor thresh-olds. These odor management plans can bestand-alone plans or part of your company’senvironmental management system.

To effectively deal with odor complaints, itis important to consider creating an odordetection and response team to identify thesource of, and quickly respond to, potentialnuisance odor conditions. Document theproblem as well as how it was or was notresolved, and notify facility managers as soonas possible. Odor complaints should be doc-umented immediately in terms of the odor’s

location, characteristics, the time and date,existing meteorological conditions, suspectedspecific source, information that indicates rel-ative strength compared to other events, andwhen during the day the odors are noticed.

Measuring odors can be accomplished intwo manners: olfactometry and analytical.The olfactometry method uses trained indi-viduals who determine the strength of anodor. Both of these methods have advantagesand disadvantages. Some of the advantages ofthe olfactometry method are that it is accu-rately correlated with human response, it isfast at providing a general chemical classifica-tion, and it is usually cost effective as a fieldscreening method. Disadvantages include therequirement of highly trained individuals,and it does not address the chemistry of theodor problem. Analytical methods use gaschromatographs and mass spectrophotome-ters to analyze vapor concentrations capturedfrom a sample. Some of the advantages of theanalytical method are that it allows detectionof odorants at levels near human detection, itis precise and repetitive, and it provideschemical specificity. Disadvantages include avery high capital cost which might not accu-rately correlate with human responses. Youshould contact your state for more informa-tion on odor management plans and measur-ing odors.

7C-22



7C-23

■■■■ Use the framework to design and evaluate a land application program and to help determine a pre-liminary waste application rate.

■■■■ Be familiar with waste parameters, such as total solids content, pH, organic matter, nutrients, car-bon and nitrogen levels, salts, soil buffering capacity, and pathogens.

■■■■ When examining potential application sites, give special consideration to physical and chemicalproperties of soil, topography, and any site characteristics that might encourage runoff or odor.

■■■■ Choose crops for the unit considering plant uptake of nutrients and constituents.

■■■■ Account for climate and its effects.

■■■■ Determine an agronomic application rate.

■■■■ Evaluate ground-water and air risks from land application units and consider potential exposurepathways.

■■■■ Consider implementing a ground-water monitoring program and periodic sampling of unit soils.

Designing a Land ApplicationProgram Activity List

7C-24


Brandt, R.C. and K.S. Martin. 1996. The Food Processing Residual Management Manual. September.

Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.

Evanylo, G.K. and W. L. Daniels. 1996. The Value and Suitability of Papermill Sludge and SludgeCompost as a Soil Amendment and Soilless Media Substitute. Final Report. Virginia Department ofAgriculture and Consumer Services. April.

Fipps, G. 1995. Managing Irrigation Water Salinity in the Lower Rio Grande Valley. <hermes.ecn.pur-due.edu/sgml/water_quality/texas/b1667.ascii>.

Gage, J. 2000. Operating by Progressive Odor Management Plan. Biocycle Journal of Composting &Recycling. Vol. 41 No. 6. June.

Idaho Department of Health and Welfare. 1988. Guidelines for Land Application of Municipal andIndustrial Wastewater. March.

Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guidance for LandApplication of Wastewater Sludge in Michigan. March.

Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guide to Preparing aResiduals Management Plan. March.

Minnesota Pollution Control Agency. 1993. Land Treatment of Landfill Leachate. February.

Nagle, S., G. Evanylo, W.L. Daniels, D. Beegle, and V. Groover. Chesapeake Bay Regional NutrientManagement Training Manual. Virginia Cooperative Extension Service. Crop & Soil EnvironmentalSciences. Virginia Polytechnic Institute and State University. Blacksburg, VA. 1997.

Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Nutrient ManagementSoftware: Proceedings from the Nutrient Management Software Workshop. NRAES-100. December.

Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Animal Agriculture and theEnvironment: Nutrients, Pathogens, and Community Relations. NRAES-96. December.

Northeast Regional Agricultural Engineering Cooperative Extension. 1993. Utilization of FoodProcessing Residuals. Selected Papers Representing University, Industry, and Regulatory Applications.NRAES-69. March.

North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling—The Key toReliable Soil Test Information. AG-439-30.

Resources


7C-25

Oklahoma Department of Environmental Quality. Title 252. Oklahoma Administrative Code, Chapter647. Sludge and Land Application of Wastewater.

Rowell, D.L. 1994. Soil Science: Methods and Applications.

Striebig, B. and R. Giani. 2000. Briefing: The Odor Index and Its Use as a Management Tool for BiosolidsLand Application. Penn State University and Pennsylvania Department of Environmental Protection.

Texas Water Commission. 1983. Industrial Solid Waste Management Technical Guideline No. 5: LandApplication. December.

University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991.Guidelines for Soil Sampling. G91-1000-A. February.

U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. AgriculturalPhosphorus and Eutrophication. July.

U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Conservation PracticesStandard: Nutrient Management, Code 590. April.

U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Core ConservationPractices, Part 2: Nutrient Management. August.

U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. National Soil SurveyHandbook. September.

U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Soil Taxonomy: A BasicSystem of Soil Classification for Making and Interpreting Soil Surveys. September.

U.S. EPA. 1995a. A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule. EPA832-B-93-005. September.

U.S. EPA. 1995b. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage.EPA625-R-95-001. September.

U.S. EPA. 1995c. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage.EPA625-R-95-002. September.

U.S. EPA. 1995d. Laboratory Methods for Soil and Foliar Analysis in Long-term EnvironmentalMonitoring Programs. EPA600-R-95-077.

Resources (cont.)

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Resources (cont.)U.S. EPA. 1994a. Land Application of Sewage Sludge: A Guide for Land Appliers on the Requirementsof the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503. EPA831-B-93-002b. December.

U.S. EPA. 1994b. Guide to Septage Treatment and Disposal. EPA625-R-94-002. September.

U.S. EPA. 1994c. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA832-R-93-003.September.

U.S. EPA. 1994d. Biosolids Recycling: Beneficial Technology for a Better Environment. EPA832-R-94-009. June.

U.S. EPA. 1993. Domestic Septage Regulatory Guidance: A Guide to the EPA 503 Rule. EPA832-B-92-005. September.

U.S. EPA. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge. EPA625-R-92-013.December.

U.S. EPA. 1990. State Sludge Management Program Guidance Manual. October.

U.S. EPA. 1983. Process Design Manual for Land Application of Municipal Sludge. EPA625-1-83-016.October.

U.S. EPA, U.S. Army Corps of Engineers, U.S. Department of Interior, and U.S. Department ofAgriculture. 1981. Process Design Manual for Land Treatment of Municipal Wastewater. EPA625-1-81-013. October.

U.S. EPA. 1979. Methods for Chemical Analysis of Water and Wastes. EPA600-4-79-020.

Viessman Jr., W. and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th ed.

Washington State Department of Ecology. 1993. Guidelines for Preparation of Engineering Reports forIndustrial Wastewater Land Application Systems. Publication #93-36. May.

Webber, M.D. and S.S. Sing. 1995. Contamination of Agricultural Soils. In Action, D.F. and L.J.Gregorich, eds. The Health of Our Soils.

Wisconsin Department of Natural Resources. 1996. Chapter NR 518: Landspreading of Solid Waste.April.

Part VEnsuring Long-Term Protection

Chapter 8Operating The Waste Management System

Contents

I. An Effective Waste Management System ..................................................................................................8-1

II. Maintenance and Operation of Waste Management System Components ................................................8-2

A. Ground-Water Controls ..........................................................................................................................8-4

B. Surface-Water Controls ............................................................................................................................8-5

C. Air Controls ............................................................................................................................................8-5

III. Operational Aspects of a Waste Management System................................................................................8-7

A. Operating Plan ........................................................................................................................................8-7

B. Waste Analysis ........................................................................................................................................8-8

C. Waste Inspections ....................................................................................................................................8-8

D. Daily Cover ..............................................................................................................................................8-9

E. Placing Wastes ......................................................................................................................................8-10

F. Sludge Removal......................................................................................................................................8-10

G. Climate Considerations ..........................................................................................................................8-11

H.Security Measures, Access Control, and Traffic Management..................................................................8-11

I. Providing Employee Training ................................................................................................................8-12

J. Emergency Response Plan and Procedures ............................................................................................8-14

K. Record Keeping ....................................................................................................................................8-16

L. Addressing Nuisance Concerns ..............................................................................................................8-17

Operating the Waste Management System Activity List ................................................................................8-20

Resources ......................................................................................................................................................8-21

Ensuring Long-Term Protection—Operating the Waste Management System

8-1

Implementing a waste management sys-tem that achieves protective environmen-tal operations requires incorporatingperformance monitoring and measure-ment of progress towards environmental

goals. An effective waste management systemcan help ensure proper operation of the manyinterrelated systems on which a unit dependsfor waste containment, leachate management,and other important functions. If the elementsof an overall waste management system are notregularly inspected, maintained, improved,and evaluated for efficiency, even the best-designed unit might not operate efficiently.Implementing an effective waste managementsystem can also reduce long- and short-termcosts, protect workers and local communities,and maintain good community relations.

I. An EffectiveWasteManagementSystem

Having an effective waste management sys-tem requires an understanding of environ-mental laws and an understanding of how tocomply with these laws. An effective wastemanagement system also requires that proce-dures be in place to monitor performance andmeasure progress towards clearly articulatedand well understood environmental goals.Lastly, an effective waste management systeminvolves operational procedures that integratecontinual improvements in waste managementoperations to ensure continued compliancewith environmental laws. In addition to whatis discussed in this chapter, you can considerreviewing and implementing, as appropriate,the draft voluntary standards for good envi-ronmental practices developed by theInternational Standards Organization (ISO).The ISO 14000 series of standards identifymanagement system elements that are intend-ed to lead to improved performance. Theseinclude: a method to identify significant envi-ronmental aspects; a policy that includes a

Operating the Waste Management System


• Develop a waste management system that includes procedures

for monitoring performance and measuring progress towards

environmental goals. The waste management system should

identify operational procedures that are necessary to achieve

those environmental goals and to make continual improve-

ments in waste management operations.

This chapter will address the followingquestions.

• What is an effective waste managementsystem?

• What maintenance and operationalaspects should be developed as part ofa waste management system?

8-2


commitment to regulatory compliance, theprevention of pollution, and continualimprovement; environmental objectives andtargets for all relevant levels and functions inthe organization; procedures to ensure perfor-mance, as well as compliance procedures tomonitor and measure performance; and a sys-tematic management review process.

The ISO 14000 series of standards includea “specification” standard, ISO 14001. The

rest are standards that provide optional guid-ance for companies developing and imple-menting management systems and productstandards. The ISO 14001 specification stan-dard contains only those requirements thatcan be objectively audited for certification,registration, and self-declaration purposes. Formore information about EPA’s involvement inthe ISO 14000 and 14001 standards, refer tothe ISO 14000 Resource Directory, October1997, (U.S. EPA, 1997). Information onobtaining the ISO 14000 series of standards isprovided in the text box above. An example ofan integrated EMS can be found at<www.epa.gov/dfe/tools/iems.htm>.

II. Maintenanceand Operation ofWasteManagementSystemComponents

All of the time and money invested in plan-ning, designing, and developing a unit will bejeopardized if proper operational proceduresare not carried out. Effective operation isimportant for environmental protection, andfor reasons of economy, efficiency, and aes-thetics. Operating control systems, therefore,should be developed and maintained by thefacility operator to ensure efficient and protec-tive operation of a waste management system.These controls consist of the operator con-ducting frequent inspections, performing rou-tine maintenance, reporting inspection results,and making necessary improvements to keepthe system functioning.

Unit inspections can help identify deterio-ration of or malfunction in control systems.Surface impoundments should be inspected

Additional Information onISO 14000

The ISO 14000 series of standards arecopyrighted and can be obtained by con-tacting any of the following organizations:

American National StandardsInstitute (ANSI)1819 L Street, NW, 6th FloorWashington, DC 20026202 293-8020<www.ansi.org>

American Society of Testing andMaterials (ASTM)100 Bar Harbor DriveWest Conshohocken, PA 19428-2959610 832-9585<www.astm.org>

American Society for QualityControl (ASQC)611 East Wisconsin AvenueP.O. Box 3005Milwaukee, WI 53201800 248-1946<www.asqc.org>

NSF InternationalP.O. Box 130140789 N. Dixboro RoadAnn Arbor, MI 48113-0140800 NSF-MARK or 734 769-8010<www.nsf.org>


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for evidence of overtopping, sudden drops inliquid levels, ice formation, and deteriorationof dikes or other containment devices.Overtopping, or the flowing of waste over thetop of the walls of an impoundment, canoccur as a result of insufficient freeboard,wind or wave action, or other unusual condi-tions including the formation and movementof ice within a surface impoundment whichcan also puncture or tear synthetic liners.

One method of protecting liners from icedamage is to install a liner cover consisting ofsand and rip rap along the edge of the liner.Another option is the use of a double linersystem. The higher cost of a double liner isoffset by reducing the need for rip rap andoffers enhanced ground-water protection.Regardless of which method is implemented,liner systems should be inspected for damageand be repaired if necessary after periods ofice formation. Also, make visual inspectionsperiodically to check waste levels, weatherconditions, or draining during periods ofheavy precipitation. In addition, it is impor-tant to consider devising a contingency planto reinforce dikes when failure is imminent.

Waste piles and landfills should beinspected for adequate surface-water protec-tion systems, leachate seeps, dust suppressionmethods, and daily covers, where applicable.Land application sites should be inspected foradequate surface-water protection systemsand dust suppression methods, as applicable.Inspections of pipes, monitoring of mechani-cal equipment, and safety, emergency, andsecurity devices will help to ensure that aunit operates in a safe manner. In addition,inspections often prevent small problemsfrom growing into more costly ones.

How should effective inspections

be conducted?

To help ensure that routine inspections areperformed regularly and consistently, considerdeveloping a written inspection schedule andensure that staff follow the schedule. Theschedule could state the type of inspections tobe conducted, the inspection methods to beused, the frequency of the inspections, and aplan of action highlighting preventative mea-sures to address potential problems. Considerconducting additional inspections after extra-ordinary site-specific circumstances, such asstorms or other extreme weather conditions.

Staff conducting the inspections shouldlook for malfunctioning or deterioratingequipment, such as broken sump pumps,leaking fittings, eroding dikes, or corrodedpipes or tanks; discharges or leaks fromvalves or pipes; and operator errors. A writ-ten schedule for inspections should be main-tained at the facility, and inspections shouldbe recorded in a log containing informationsuch as date of inspection, name of inspector,conditions found, and recommended correc-tive action. Inspection personnel should befamiliar with the inspection log to identifyany malfunctions or deficiencies that remainuncorrected from previous inspections.

When designing an inspection form for aunit, add appropriate items for the unit type.You can check with the appropriate state reg-ulatory agency to see if it has an inspectionform that can be used. For example, a landfillform would include a section about wasteplacement and a surface impoundment formmight have an entry for sufficient freeboard.If ground water is monitored, you can makeground-water monitoring part of the unitinspection, and add check boxes for eachmonitoring point to ensure that inspectorscollect samples from all monitoring pointsaccording to the specified schedule. After an

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inspection, it is important that all inspectionreports are reviewed in a timely manner sothat any necessary repairs and improvementscan quickly be identified and implemented.You should consult with your state agency tohelp determine if improvements are necessary.

A. Ground-Water ControlsGround-water protection controls, such as

ground-water monitoring systems, unit covers,leachate collection and removal systems, andleak detection systems should be incorporatedinto the design and construction of a unit.

Ground-water monitoring wells requirecontinued maintenance. A major reason formaintenance is plugging of the gravel pack orscreen. (See Chapter 9–MonitoringPerformance for a discussion on the construc-tion of ground-water monitoring wells.) Themost common plugging problems are causedby precipitation of calcium or magnesium car-bonates and iron compounds. Acid is mostcommonly used to clean screens clogged withcalcium carbonate. In many instances, howev-er, the cost of attempted restoration of a moni-toring well can be more than the installation ofa new well. Because many wells are installedin unconsolidated sand formations, silt andclay can be pumped through the system andcause it to fail. Silt and sand grains are abra-sive and can damage well screens, pumps (ifpresent), flow meters, and other components.

In some cases, the well can fill with sedi-ment and must be cleaned out. The most fre-quent method of cleaning is to pull the pumpfrom the well, circulate clean water down thewell bore through a drop, and flush the sedi-ment out. If large amounts of sediments areexpected to enter a monitoring well, considerincorporating a sediment sump (also called asilt trap or sediment trap) into the monitoringwell construction. The sump consists of ablank section of pipe placed below the base ofthe screen. Its purpose is to provide a catch-

trap for fine sand and silt which bypasses thefilter pack and screen and settles out withinthe well. This sediment collects within thesump rather than within the screen, and there-fore, does not reduce the functional screenedlength of the well and minimizes the need forperiodic cleanouts of the screen. Regardless ofthe type of ground-water monitoring wellinstalled, the well should be protected with acap or plug at the upper end to prevent con-densation, rust, and dirt from entering into themanhole or protective casing. In addition, it isimportant to inspect the outer portion of thewells to ensure that they have not been dam-aged by trucks or other unit operations, and toensure that the cap or plug is intact.

You also should inspect and maintain unitcovers to ensure that they are intact. For opti-mal performance, covers should be designedto minimize permeability, surface ponding,and the erosion of cover material. The covershould also prevent the buildup of liquidswithin the unit. Consult Chapter11–Performing Closure and Post-Closure Carefor a more detailed discussion on maintainingcover systems.

It is essential that all components of aleachate collection and removal system and aleak detection system be maintained properly.The main components include the leachatecollection pipes, manholes, leachate collectiontanks and accessories, and pumps. You shouldconsider cleaning the leachate pipes once ayear to remove any organic growth and visual-ly inspecting the manholes, tanks, and pumpsonce a year as leachate can corrode metallicparts. Annual inspections and necessaryrepairs will prevent many future emergencyproblems such as leachate overflow from thetank due to pump failure. Maintain a record ofall repair activities as necessary to assess (orclaim) long-term warranties on pumps andother equipment.


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In surface impoundments, monitor wasteliquid levels. An unexpected decrease in liq-uid levels can be an indication of a releasefrom the impoundment. If a surfaceimpoundment fails, it is important to discon-tinue adding waste to the impoundment andcontain any discharge that has occurred or isoccurring. Repair leaks as soon as possible. Ifleaks cannot be stopped, empty theimpoundment if possible. If the size of theunit or amount of waste present prohibitsemptying, see Chapter 9–MonitoringPerformance and consult with state officialsabout beginning an assessment monitoringprogram. Clean up any released waste (seeChapter 10–Taking Corrective Action) andnotify the appropriate state authorities of thefailure and the remedial actions taken.

B. Surface-Water ControlsIf a unit has a point source discharge, the

unit must have a National PollutantDischarge Elimination System (NPDES) per-mit (or equivalent) and, in some states, mightrequire a state discharge permit. Point sourcedischarges include the release of leachatefrom a leachate collection or onsite treatmentsystem into surface waters, disposal of indus-trial waste into surface waters, or release ofsurface-water runoff (e.g., storm water) that isdirected by a runoff control system into sur-face waters. Even if there are no point sourcedischarges, surface-water controls might benecessary to prevent pollutants from beingdischarged or leached into surface waters,such as lakes and rivers. If a facility is dis-charging wastewater to a local publiclyowned treatment works (POTW), check withthe POTW and local regulatory authorities todetermine whether pretreatment standardsexist for the facility.

Soil erosion and sedimentation controls,such as ditches, berms, dikes, drains, and siltfences, should be incorporated into the

design and construction of a unit. Berms ordikes are often constructed from earthenmaterials, concrete, or other materialsdesigned to be safely traversed during inspec-tion or monitoring activities. Vegetation alsois often used for erosion control. Trees orother deep rooted vegetation, however,should not be used near liners or other struc-tures that could be damaged by roots. Grassis often used for soil stabilization around sur-face impoundments. For a more detailed dis-cussion of storm-water issues, consultChapter 6–Protecting Surface Water.

Most if not all of these surface-water con-trols should be inspected by the operator reg-ularly, especially after large storm events.Structures should be maintained as installedand any structural damage should be repairedas soon as possible to prevent further damageor erosion. Any trapped sediments should beremoved and disposed of properly. Vegetativecontrols frequently need watering after planti-ng and during periods of intense heat or lackof rain.

C. Air ControlsGases, including methane, carbon dioxide,

and hydrogen, are often produced at wastemanagement units as byproducts of themicrobial decomposition of wastes containingorganic material. Additionally, volatile organiccompounds (VOCs) can be present in thewaste, and particulate emissions and dust canbe generated during unit operations. It isimportant to analyze wastes carefully prior todesigning a waste management unit to deter-mine what airborne emissions are likely tocome from these wastes. If airborne emissioncontrols are needed in the design of a unit,maintenance of these controls should be con-sidered as part of a waste management sys-tem. For further information on airborneemission controls, consult Chapter 5–Protecting Air Quality.

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Methane is a particular concern at somewaste management units. Methane is odorlessand can cause fires or explosions that canendanger employees and damage structuresboth on and off site. Hydrogen gas can alsoform, and is also explosive, but it readilyreacts with carbon or sulfur to form methaneor hydrogen sulfide. Hydrogen sulfide can beeasily identified by its sulfur or “rotten egg”smell. Methane, if not captured, will eitherescape to the atmosphere or migrate under-ground. Underground methane can enterstructures, where it can reach explosive con-centrations or displace oxygen, creating thedanger of asphyxiation. Methane in the soilprofile can damage the vegetation on the sur-face of the landfill or on the land surroundingthe landfill, thereby exposing the unit toincreased erosion. Finally, methane is apotent “greenhouse” gas that contributes toglobal warming.

Methane is explosive when present in theranges of 5 to 15 percent by volume in theair. The 5 percent level is known as the lowerexplosive limit (LEL) and 15 percent as theupper explosive limit (UEL). At levels above15 percent by volume, methane will notexplode when exposed to a source of igni-tion. Levels above the UEL remain a concern,however, as methane will burn at these con-centrations and can still cause asphyxiation.

In the event that methane gas levels exceed25 percent of the LEL in facility structures orother closed spaces, initiate safety measures,such as evacuating the site and structures. Insuch cases, or when the methane levelexceeds 25 percent of the LEL in the soil at amonitoring point, implement a remediationplan to decrease gas levels and prevent futurebuildup of gases.

Gas control systems generally includemechanisms designed to control gas migra-tion and to minimize the venting of gas emis-sions into the atmosphere. Passive gas controlsystems use natural pressure and convectionmechanisms to remove gas from the wastemanagement unit. Examples of passive gascontrol system elements include ditches,trenches, vent walls, perforated pipes sur-rounded by coarse soil, synthetic membranes,and high moisture, fine-grained soil. Activegas control systems use mechanical means toremove gas from the unit. Gas extractionwells are an example of an active gas controlsystem.

Gas monitoring and extraction systemsrequire regular maintenance to operate effi-ciently. As wastes settle over time, pipes canfail and condensate outlets can becomeblocked. Extracted gas is saturated, whichcauses moisture to collect within the pipes.Therefore, the condensate within the pipesmust be dealt with, otherwise it will affect thepumping suction pressure. Since the plumb-ing on the top of the unit is quite involved,develop and adhere to a gas maintenanceschedule to ensure the efficient operation ofgas systems.

If generated gas is not removed from aunit, uplift pressure can cause bubbles withinthe unit that displace the cover soil at thesurface. Gas bubbles also can decrease thenormal stress between the geomembrane andits underlying material leading to slippage ofthe geomembrane and all overlying materials.This creates high tensile stresses evidenced byfolding at the toe of the slope and tensioncracks near the top.


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III. OperationalAspects of aWasteManagementSystem

This section identifies and briefly discussessome of the important operational aspects ofa waste management system, including devel-oping an operating plan, performing wasteanalyses and inspections, installing daily cov-ers, placing wastes in a unit, removingsludge, considering climate, implementingsecurity and access control measures, provid-ing employee training, addressing nuisanceconcerns, developing emergency responseplans and procedures, and maintainingimportant records. Consider developing prac-tices to ensure compliance with applicablelaws and regulations, to train workers how tohandle potential problems, and to ensure thatall necessary improvements or changes aremade to a waste management system. Properplanning and implementation of these operat-ing practices are important elements in theefficient and protective operation of a unit.

A. Operating PlanAn operating plan should serve as the pri-

mary resource document for operating awaste management unit. It should include thetechnical details necessary for a unit to oper-ate as designed throughout its intendedworking life. At a landfill, for example, theoperating plan should illustrate the chrono-logical sequence for filling the unit, and itshould be detailed enough to allow the facili-ty manager to know what to do at any pointin the active life of the unit.

An operating plan should include:

• A daily procedures component.

• Lists of current equipment holdingsand of future equipment needs.

• Procedures to inspect for inappropri-ate wastes and to respond when theirpresence is suspected.

• Procedures for addressing extremeweather conditions.

• Personnel needs and equipment uti-lization, including backup.

• Procedures to address emergencies,such as medical crises, fires, and spills.

• Quality control standards.

• Record keeping protocols.

• Means of compliance with local,state, and federal regulations.

The daily procedures component of the planoutlines the day-to-day activities necessary toplace waste, operate environmental controls,and inspect and maintain the waste manage-ment unit in accordance with its design. Dailyprocedures should be concise enough to be cir-culated among all employees at the unit andflexible enough to allow for any adjustmentsnecessary to accommodate weather variability,changing waste volume, and other contingen-cies. You should revise and update daily proce-dures as needed to ensure the unit’s continuedsafe operation within the parameters of theoverall operating plan.

Since a unit will likely operate for severalyears, it is important that staff periodicallyreview the operating plan to refresh theirmemories and to ensure long-term conformi-ty with the plan. If modifications to the oper-ating plan are necessary, the changes and thedate they were made should be noted withinthe plan itself. Documented operating proce-dures can be crucial, especially if questionsarise in the future regarding the adequacy ofsite construction and management.

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B. Waste AnalysisTo effectively manage waste and ensure

proper handling (e.g., preventing the mixingof incompatible wastes, use of incompatibleliners or containers), knowledge of the chem-ical and physical composition of the wastes isimperative. Determining waste characteristicscan be done by performing a comprehensivewaste analysis or through process knowledge.To ensure that this information remains accu-rate, it might be necessary to repeat theanalysis whenever there is a change in theindustrial process generating the waste. Forfurther information, consult Chapter2–Characterizing Waste.

C. Waste InspectionsThe purpose of performing waste inspec-

tions is to identify waste that might be inap-propriate for the waste management unit, andto prevent problems and accidents beforethey happen. Hazardous wastes, PCBs, liq-uids (in landfills and waste piles), and state-designated wastes are prohibited fromdisposal in units designated solely for indus-trial nonhazardous waste. Some states havedeveloped more stringent screening require-ments that require a spotter to be present at aunit to detect unauthorized wastes and toweigh and record incoming wastes.

As part of a waste management system,screening procedures should be implementedto prevent inappropriate wastes from enteringa unit. For units receiving waste exclusivelyfrom on site, only limited waste screeningmight be necessary. For facilities receivingwaste from off site, screening procedures typi-cally call for screening waste as it enters aunit. Ideally, all wastes entering a unit shouldbe screened, but this is not always practical ornecessary. A decision might be made, there-fore, to screen a percentage of incomingwaste. It might be practical to use spot inspec-

tions, such as checking random loads of wasteon a random day each week or every incom-ing load on one random day each month.Base the frequency of random inspections onthe type and quantity of wastes expected to bereceived, the accuracy and confidence desired,and any state inspection requirements.Inspections need to be performed prior toplacement of wastes in a unit.

Training employees to recognize inappro-priate wastes during routine operationsincreases the chances that inappropriatewaste arriving on non-inspection days will bedetected. Some indications of inappropriatewastes are color, texture, or odor differentfrom those of the waste a unit normallyreceives. Also, laboratory testing can be per-formed to identify different wastes.

A waste management system shouldinclude procedures to address suspectedinappropriate waste. The procedures toimplement, when inappropriate wastes arefound, should include the following:

• Segregate the suspicious wastes.

• Use appropriate personal protectiveequipment.

• Contact the part of the industrialfacility that generated the waste tofind out more about it.

An effective waste management system

relies on accurate knowledge of the waste

being handled.


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1 EPA is investigating the potential of bioreactor landfills as the concept applies to the operation of amunicipal landfill. The idea of a bioreactor landfill might be considered appropriate in select cases foran industrial landfill at some time in the future.

2 In Pennsylvania a coproduct is defined as “materials which are essentially equivalent to and used inplace of an intentionally manufactured product or produced raw material and...[which present] nogreater risk to the public or the environment.”

• Contact laboratory support to analyzethe waste, if required.

• Call the appropriate state, tribal orfederal agencies in accordance withthe opertaing plan.

• Notify a response agency, if necessary.

Should liquids be restricted from

being placed in some units?

Bulk or containerized liquids should notbe placed in landfills or waste piles, as liquidsincrease the potential for leachate generation.Liquid waste includes any waste materialdetermined to contain free liquids as definedby Method 9095 (also known as the paint fil-ter test) in EPA’s Test Methods for EvaluatingSolid Waste, Physical/Chemical Methods (SW-846). Sludges are a common waste that cancontain significant quantities of liquids. Youshould consider methods such as drying bedsto dewater sludges prior to placement inlandfills and waste piles.1

D. Daily CoverIt might be necessary to apply a daily

cover to operating landfills and waste piles.Covering the waste helps control nuisancefactors, such as the escape of odors, dust, andairborne emissions, and can control the pop-ulation of disease vectors where necessary.Some cover materials, due to their ability tohold moisture, can reduce the infiltration ofrain water, decreasing the generation ofleachate and the potential for surface-waterand ground-water contamination.

How is daily cover applied?

Covers most often consist of earthen mate-rial, although there are several alternativedaily covers being used in the industry today,

including coproducts,2 foam, geotextiles, andplastic sheets or tarps. Examples of coprod-ucts that have been used as daily coverinclude granular wastes, automobile shredderfluff, foundry sand, dewatered sludges, andsynthetic soils. When using coproduct coversthat can themselves contain contaminants,ensure that run-on is either diverted before itcontacts the cover material or captured andhandled appropriately after contacting it.Granular wastes used as daily cover shouldbe low in fine-grained particles to avoid wastebeing transported by wind. Before using alter-native covers, especially coproducts, youshould consult the state to determine what, ifany, regulations apply.

Daily cover should be applied after thewaste has been placed, spread, and compact-ed. Cover frequency is most often determinedby the type of industrial waste disposed of atthe landfill or waste pile. Frequent applica-tion of earthen material might be required ifundesirable conditions persist. A typical dailysoil cover thickness is 6 inches, but differentthicknesses might be sufficient. When usingearthen cover, it is important to avoid soilswith high clay content. Clay, due to its lowpermeability, can block vertical movement ofwater and channel it horizontally through thelandfill or waste pile.

Inspect waste to ensure that hazardous

waste is not placed in a unit.

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Using alternative daily cover materials cansave valuable space in a waste managementunit. Some types of commercially availabledaily cover materials include foam that usual-ly is sprayed on the working face at the endof the day, and geosynthetic products, such asa tarp or fabric panel that is applied at theend of the working day and removed at thebeginning of the following working day.Some of these materials require speciallydesigned application equipment, while othersuse equipment generally available at mostunits. Criteria to consider when selecting analternative daily cover material include avail-ability and suitability of the material, precipi-tation, chemical compatibility with waste,equipment requirements, and cost.

E. Placing WastesTo protect the integrity of liner systems,

the waste management system should pre-scribe proper waste placement practices. Theprimary physical compatibility issue is punc-ture of the liner by sharp objects in the waste.Ensure that the liner is protected from itemsangular and sharp enough to puncture it.Similarly, facility employees should beinstructed to keep heavy equipment off theliner. Another physical compatibility issue iskeeping fine-grained waste materials awayfrom drainage layers that could be clogged bysuch materials.

Differential settlement of wastes is anotherproblem that can be associated with wasteplacement. To avoid differential settlement,focus on how the waste is placed on the linermaterial or on the protective layer above theliner. Uneven placement of waste, or unevencompaction can result in differential settle-ment of succeeding waste layers or of finalcover. Differential settlement, in turn, can leadto ponding and infiltration of water and dam-age to liners or leachate collection systems. Inextreme cases, failure of waste slopes can

occur. To avoid these problems, it is impor-tant to ensure that waste is properly placedand, if possible, compacted to ensure stabilityof the final cover.

To protect liner integrity in lined surfaceimpoundments, consider placing an erosionguard or a concrete pad on the liner at thepoint where waste discharges into the unit.Otherwise, pressure from the waste hittingthe liner can accelerate liner deterioration inthat area. Inlet pipes can also be arranged sothat liquid waste being discharged into theunit is diffused upward or to the side.Although inlet pipes can enter the surfaceimpoundment above the water level, thepoint of discharge should be submerged toavoid generating odor and disturbing the cir-culation of stratified ponds. Discharging liq-uid waste straight into the unit withoutdiffusion is not recommended as this can dis-rupt the intended treatment.

F. Sludge RemovalIf significant amounts of sludge accumu-

late on the bottom of an impoundment, itmight be necessary to remove the sludge anddispose of it periodically. There are two waysto remove the sludge: dewater the cell andremove the sludge after it has dried, ordredge the impoundment. Many differentmethods exist for dredging an impoundment.Examples include a tanker truck outfittedwith a vacuum hose, manned and remotedredges, and submersible pumps on steelpontoons used as a floating dredge ordragged on the pond bottom. You shouldwork with your state and sludge removal pro-fessionals to choose or create a method thatworks best at your facility.

There are two main concerns regardingsludge management: protecting the linerwhile cleaning out sludge from the impound-ment (if a liner is used) and properly dispos-ing of any removed sludge. During dredging,

heavy equipment can damage the liner. Youcan avoid this by selecting equipment andmethods that protect the liner during sludgeremoval. Further, any sludge removed shouldbe evaluated and managed in an appropriatemanner, based on its chemical properties.

G. Climate ConsiderationsWaste management operations can be

affected by weather conditions, especiallyrain, snow, or wind. Rainy or snowy weathercan create a variety of problems, such as hin-dered vehicle access and difficulty in spread-ing and compacting waste. To combat thesedifficulties, consider altering drainage pat-terns, maintaining storm-water controls,maintaining all-weather access roads (ifappropriate), or designating a wet-weatherdisposal area.

Extremely cold conditions can prevent effi-cient excavation of soil from a borrow pit andcan also inhibit the spreading and com-paction of soil cover on the waste. Freezingtemperatures can also inflict excessive wearon equipment. To combat these problems,you can use coarse-textured soil during win-ter operations, stockpile cover soil for winteruse, and protect cover soil with leaves, plas-tics, or other insulating materials.

Consider using special inclement weatherdisposal areas during extreme wet and windyweather. In wet weather, placing waste in apart of the unit near the entrance reduces thelikelihood of trucks causing ruts on site road-ways or being stranded in mud. Under windyconditions, waste might need to be wetted orplaced in downwind areas of a unit to reduceblowing waste or particulates.

H. Security Measures,Access Control, andTraffic Management

To prevent injury to members of the pub-lic, consider implementing security andaccess control measures to block unautho-rized entry to a unit. These measures can alsohelp to prevent scavenging, vandalism, andillegal dumping of unauthorized wastes.Providing access controls for the facility with-in which the unit is located is an example ofproviding such measures for the unit.

Examples of access control measuresinclude fences, locked gates, security guards,and surveillance systems; and natural barrierssuch as, berms, trees, hedges, ditches, andembankments. The site perimeter should beclearly marked or fenced. Additionally, consid-er posting signs that warn of restricted accessand alert the public to the potential for harmassociated with heavy equipment operations.

How can onsite traffic best be

managed?

Even though access to the unit is limited,it is important to provide clear transportationroutes for emergency response equipment toaccess the waste management unit. Trafficmanagement is often overlooked as part ofwaste management unit operations. Propertraffic routing can help a unit operate moresmoothly and prevent injuries and deterintruders. Access roads should be designedand built to be safe and efficient, and blindspots or unmarked intersections should beminimized. They should also be located toprovide long-term service without requiringrelocation. Posting clear directional signs canhelp direct traffic and reduce the potential forvehicle accidents. Providing all-weatheraccess roads (if appropriate) and temporarystorage areas can improve waste transport toand from a unit and allow equipment to


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8-12


move about more freely. In addition, you canconsider imposing onsite speed limits or con-structing speed bumps.

Access roads should be maintained proper-ly at all times. Adequate drainage of roadbeds is essential for proper operation of aunit. Heavy, loaded vehicles traveling to andfrom a unit deteriorate the roads on whichthey travel. Equipment without rubber tiresshould be restricted from the paved stretchesof roads as they can damage the roads.Sufficient funds should be allocated up frontfor the maintenance of access roads.

What are some other prudent

safety measures?

There are a number of safety considera-tions associated with ground-water monitor-ing wells. The tops of monitoring wellsshould be clearly marked and accessible. Intraffic areas, posts and bumper guards aroundmonitoring wells can help protect above-ground installations from damage. Posts andbumper guards come in various sizes andstrengths and are typically constructed forhigh visibility and trimmed with reflectivetape or highly visible paint containing reflec-tive material.

Proper labeling of monitoring wells is alsoimportant for several reasons. Monitoringwells should be distinguished from under-ground storage tank fill lines, for example.Also, different monitoring wells should bedistinguished from each other. Monitoringwells, therefore, should be labeled on immov-able parts of the well.

I. Providing EmployeeTraining

One of the most important aspects of awaste management system is employee train-ing. Employees should be trained before theirinitial assignment, upon changing assign-

ments, and any time a new health or safetyhazard is introduced into the work area. Agood training program uses concrete exam-ples to improve and maintain employee skill,safety, and teamwork. Training can be provid-ed by in-house trainers, trade associations,computer programs, or specialized consul-tants. In some states, proactive safety andtraining programs are required by law.

What types of training can be

provided for employees?

Safety is a primary concern because wastemanagement operations can present a varietyof risks to workers. In addition, employeeright-to-know laws require employers to pro-vide training and information about safetyissues pertinent to a given occupation.Furthermore, accidents can be expensive,with hidden costs often amounting to severaltimes the apparent costs. Accidents at wastemanagement units can include injury fromexplosions or fire, inhalation of contaminantsand dust, asphyxiation from poorly ventedleachate collection system manholes or tanks,falls from vehicles, injury associated withoperating heavy earth-moving equipment,exposure to extreme cold or heat, and onsitetraffic accidents.

To minimize risks to workers, it is rec-ommended that you provide an ongoingsafety training program to ensure all staff

Classroom training helps familiarize employeeswith operating procedures.

are properly and regularly trained on safetyissues. A safety training program should beconsistent with the requirements specifiedby the U.S. Occupational Safety and HealthAdministration (OSHA) and include initialtraining and frequent refresher sessions onat least the following topics:

• Waste management operations.

• Hazardous waste identification.

• Monitoring equipment operations.

• Emergency shut-off procedures.

• Overview of safety, health, and otherhazards present at the site.

• Symptoms and signs of overexposureto hazards.

• Proper lifting methods, material han-dling procedures, equipment opera-tion, and safe driving practices.

• Emergency response topics, such asspill response, fire suppression, haz-ard analysis, and location and op-eration of emergency equipment.

• Requirements for personal protectivegear, such as hard hats, gloves, gog-gles, safety shoes, and high-visibilityvests.

Weave a common thread of teamwork intoevery training program. Breaks in communica-tion between site engineers and field opera-tions personnel can occur. Bridging this gap isan important step toward building an effectiveunit team that can work together. Considerperiodic special training to update employeeson new equipment and technologies, toimprove and broaden their range of job-relatedskills, and to keep them fresh on the basics.Training can also include such peripheral top-ics as liability concerns, first aid, avoidance ofsubstance abuse, and stress management.


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Sample Manager andSupervisor Training Agenda• Introduction

• Unit basics:

—Siting

—Waste containment

—Daily operations

• Owning and operating costs

• Machine types

• Equipment maintenance

• Maximizing airspace

• Labor management

• Production analysis

• Application of production rate data

• Budgets and data tracking:

—Operating budget

—Cover soil budget

—Airspace budget

• Waste handling techniques

• Waste management techniques

• Cover soil placement

• Safety issues and safety meetings

• Record keeping

• Emergency response plan

• State requirements for operation

Bolton, N. 1995. The Handbook of LandfillOperations: a Practical Guide for LandfillEngineers, Owners, and Operators. (ISBN 0-9646956-0-X). Reprinted by permission.

How should training programs

be conducted?

You should keep records of the type andamount of training provided to employees,and obtain documentation (employee signa-tures) whenever training is given. Consider

establishing regular (at least monthly) safetymeetings, during which specific topics can beaddressed and employees can voice concerns,ask questions, and present ideas. Keep meet-ings short and to the point, and steer discus-sion toward topics that are applicable tothose employees present. In addition, do notwaste time talking about issues not applica-ble to a site. If a site experiences extremeweather conditions, develop safety meetingtopics that address weather-related safety.Many safety-related videos are available andcan add variety to meetings.

Closely monitor worker accident andinjury reports to try to identify conditionsthat warrant corrective or preventive mea-sures. In addition, it is wise to document allsafety meetings. Assistance in establishing asafety program is available from insurancecompanies with worker’s compensation pro-grams, the National Safety Council, safetyconsultants, and federal and state governmentsafety organizations. The overall cost of anaggressive, preventive safety program isalmost certain to be offset by the savings froma decrease in lost work time and injuries.

J. Emergency ResponsePlan and Procedures

There are three major types of waste man-agement emergencies: accidents, spills, andfires/explosions. A waste management systemshould include emergency response plans foreach of these scenarios that considers notonly the waste management unit but also allsurrounding facility areas. The plans shouldbe reviewed and revised periodically to keepthe procedures fresh in employees’ minds andto reflect any changes in such items as theunit operating procedures, facility operations,physical and chemical changes in the wastes,generated volumes, addition or replacementof emergency equipment, and personnelchanges. If an emergency does arise, or if haz-

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Equipment OperatorTraining Agenda• Introduction

• Unit basics:

—Siting


—Daily operations

• Heavy equipment types and applications:

—Scraper, dozer, and compactoroperations

—Support equipment

—Fluids

—Fueling, maintenance and itshazards, and fuel spill prevention

• Cover operations:

—Types of cover soil

—Placement of cover soil

• Drainage control

• Surveying and staking

• Unit safety:

—Emergency response plans

—Safe operating techniques

• Owning and operating costs


ardous waste is inadvertently disposed of in aunit, notify appropriate agencies, adjacentland owners, and emergency response person-nel, if needed. After emergency conditionshave been cleared, review the waste manage-ment system and revise it, if necessary, to pre-vent similar mishaps in the future.

A facility might be required to prepare sim-ilar emergency response or contingency plansunder other regulatory programs [e.g., SpillPrevention Control and Countermeasures andResponse Plan requirements (40 CFR Part112.7(d) and 112.20-21); Risk ManagementProgram regulations (40 CFR Part 68); andHAZWOPER regulations (29 CFR 1910.120)].EPA encourages facilities to consolidate emer-gency response plans whenever possible toelimante redundancy and confusion. TheNational Response Team, chaired by EPA, hasprepared its Integrated Contingency PlanGuidance (61 FR 28642; June 5, 1996) as amodel for integrating such plans.

How should an appropriate

emergency response plan be

developed?

An emergency response plan should con-sider the following:

• Description of types of emergencies thatwould necessitate a response action.

• Names, roles, and duties of primaryand alternate emergency coordinators.

• Spill notification procedures.

• Who should be notified.

• Fire department or emergencyresponse telephone number.

• Hospital telephone number.

• Primary and secondary emergencystaging areas.

• Location of first aid supplies.

• Designation and training of severalfirst aid administrators.

• Location of and operating proceduresfor all fire control, spill control, anddecontamination equipment.

• Location of hoses, sprinklers, orwater spray systems and adequatewater supplies.

• Description and listing of emergencyresponse equipment.


8-15

Sample Laborer TrainingAgenda• Introduction

• Unit basics:

—Siting


—Daily operations

• Traffic management and safety

• Interacting with the public

• Load segregation and placement

• Hazardous material identification pro-cedure

• Unit equipment types and applications

• Cover operations

• Equipment maintenance

• Unit safety:

—Heavy equipment safety

—Traffic safety

—Personal protective equipment

• Emergency response plans


• Maintenance and testing log of emer-gency equipment.

• Plans to familiarize local authorities,local emergency response organiza-tions, and neighbors with the charac-teristics of the unit and appropriateand inappropriate responses to vari-ous emergency situations.

• Information on state emergencyresponse teams, response contractors,and equipment suppliers.

• Properties of the waste being handledat the unit, and types of injuries thatcould result from fires, explosions,releases, or other mishaps.

• An evacuation plan for unit person-nel (if applicable).

• Prominent posting of the aboveinformation.

The emergency plan should instruct allemployees what to do if an emergency arises,and all employees should be familiar with theplan and their responsibilities under it. Inorder to ensure that everyone knows what todo in an emergency, EPA recommends con-ducting periodic drills. These practice re-sponses could be planned ahead of time orthey could be unannounced. Either way, thedrills are treated as real emergencies andserve to hone the skills of the employees whomight have to respond to actual emergencies.The key to responding effectively to an emer-gency is knowing in advance what to do.

Communication is vital during an emer-gency and should be an inherent componentof any emergency response plan. Two-wayradios and bullhorns can prove invaluable inthe event of an emergency, and an alarm sys-tem can let employees know that an emer-gency situation is at hand. It is recommendedthat you designate one or more employeeswho will not be essential to the emergency

response to handle public affairs during amajor emergency. These employees shouldwork with the press to ensure that the publicreceives an accurate account of the emergency.

K. Record Keeping Record keeping is a vital part of cost-effec-

tive, efficient waste management unit opera-tions. Records should be maintained for anappropriate period of time, but it is a goodidea to keep a set of core records indefinitely.Some facilities have instituted policies thatrecords are to be maintained for up to 30years while other facilities maintain recordsfor only 3 years. Some states have recordkeeping requirements for certain waste man-agement units and associated practices. Youshould check with state authorities to deter-mine what, if any, record keeping is requiredby law and to determine how long recordsshould be kept.

Besides being required by some states,records help evaluate and optimize unit per-formance. Over time, these records can serveas a valuable almanac of activities, as well asa source of cost information to help fine tunefuture expenditures and operating budgets.Data on waste volume, for example, canallow a prediction of remaining site life, anyspecial equipment that might be needed, andpersonnel requirements. Furthermore, if a

8-16

Keeping accurate records is an essential part

of unit operations.


facility is ever involved in litigation, accurate,dated records can be invaluable in establish-ing a case.

What type of records should be

kept?

Operational records that should be main-tained include the following, as appropriate:

• Waste analysis results.

• Liner compatibility testing (where aliner system is considered appropriate).

• Waste volume.

• Location of waste placement, includ-ing a map.

• Depth of waste below the final coversurface.

• Inventory of daily cover materialused and stockpile.

• Frequency of waste application.

• Equipment operation and mainte-nance statistics.

• Environmental monitoring data andresults.

• Inspection reports, including pho-tographs.

• Design documents, including draw-ings and certifications.

• Cost estimates and other financialdata.

• Plans for unit closure and post-clo-sure care.

• Information on financial assurancemechanisms.

• Daily log of activities.

• Calendar of events.

Health and safety records that should bemaintained include the following:

• Personal information and work historyfor each employee, including healthinformation such as illness reports.

• Accident records.

• Work environmental records.

• Occupational safety records, includ-ing safety training and safety surveys.

L. Addressing NuisanceConcerns

Minimizing nuisances, such as noise, odor,and disease vectors, is of great importance forthe health of personnel working in the indus-trial facility and of neighbors that live or worknear a unit. This section describes many ofthe nuisance concerns typical of waste man-agement units and offers measures to addressthem. Measures besides those listed can alsobe used to achieve the same objective.

How can noises be minimized?

Noise resulting from the operation ofheavy equipment can be a concern for wastemanagement units located near residentialareas. Noise can also disrupt animal habitatsand behavior. In addition, workers’ hearingand stress levels can be adversely affected bylong-term exposure to noise. At waste man-agement units where noise is a concern, lim-iting hours of operation can reduce potentialproblems. Design access routes to minimizethe impact of site traffic noise on nearbyneighborhoods. Equipment should also bemaintained to minimize unnecessary noise,and affected workers should wear ear protec-tion (plugs or muffs). Berms, wind breaks, orother barriers can be erected to help mutesounds. OSHA has established standards foroccupational exposure to noise (see 29 CFR§1910.95).


8-17

How can odor be minimized?

Increased urbanization has led to industri-al facilities being situated in close proximityto residential areas and commercial develop-ments. This has resulted in numerous com-plaints about odors from industrial wastemanagement units and industrial processessuch as poultry processing, slaughtering andrendering, tanning, and manufacture ofvolatile organics. Some of the major sourcesof odors are hydrogen sulfide and organiccompounds generated by anaerobic decom-position. The latter can include mercaptans,indole, skatole, amines, and fatty acids. Odormight be a concern at a unit, depending onproximity to neighbors and the nature of thewastes being managed. In addition to causingcomplaints, odors can be a sign of toxic orirritating gases or anaerobic conditions in aunit that could have adverse health effects orenvironmental impacts. Plan to be proactivein minimizing odors, and establish proce-dures to respond to citizen complaints aboutodor problems and to correct the problems.

Odors can be seasonal in nature and,therefore, can often be anticipated. Someodors at landfills, waste piles, and land appli-cation units arise either from waste beingunloaded or from improperly covered in-place waste. If odor from waste beingunloaded becomes a problem, it might benecessary to place these loads in a portion ofthe unit where they can be immediately cov-ered with soil. At land application units,quick incorporation or injection of waste canhelp prevent odor. It also might be prudent toestablish a system whereby unit personnel arenotified when odorous wastes are coming tothe unit to allow them to prepare accordingly.Odors from in-place waste can effectively beminimized by maintaining the integrity ofcover material over everything but the cur-rently active face. Proper waste compactionalso helps to control odors. Consider imple-

menting gas controls if odors are associatedwith gases generated from a unit.

If odors emanate from surface impound-ments, there are several options available forcontrol, including biological and chemicaltreatment. The type of treatment for animpoundment should be determined on asite-specific basis, taking into account thechemistry of the waste.

Practices to control odor are especiallyimportant at land application units. If landapplication is used, it is important to applywaste at appropriate rates for site conditions,and design and locate waste storage facilitiesto minimize odor problems. Make it a priorityto minimize potential odors by applyingwastes as soon as possible after delivery andincorporating wastes into the soil as soon aspossible after application. Cleaning trucks,tanks, and other equipment daily (or more fre-quently, if necessary) can also help reduceodor. Avoid applying waste when soils are wetor frozen or when other soil or slope condi-tions would cause ponding or poor drainage.Chapter 7 Section C– Designing a LandApplication Program presents informationconcerning an odor management plan for landapplication facilities.

Other methods of controlling odorsinclude:

• Covering or enclosing the unit.

• Adding chemicals such as chlorine,lime, and ferric chloride to reducebacterial activity and oxidize manyproducts of anaerobic decomposition.

• Using biofilters.

• Applying a deep soil cover, whoseupper layers consist of silty soils orsoils containing a large percentage ofcarbon or humic material.

• Applying a layer of relatively imper-meable soil, so as to reduce gas gen-

8-18


eration rates by reducing the amountof rainfall water percolating into thewaste.

• Restoring landfill surface covers whensubsidence and cracks occur.

Choosing a method for controlling odorsinvolves a comprehensive understanding ofwastes and how they react under certain cir-cumstances. Consult with state agencies todetermine the most effective odor controlmethod for the wastes in question.

In addition to these steps to control odorgeneration, consider steps to manage thoseodors that are generated. When designing awaste management unit, consider installingbarriers such as walls, berms, embankments,and dense plantings of trees set at rightangles to the flow of cold, odorous night-time air. These measures can help to impedethe odor and dilute it through mixture withhigher layers of fresh air. Alternatively, con-sider placing an impermeable fence or wallon top of a berm or embankment, on itsdownwind side. This will increase odorplume height, and odors will be diluted onthe steep downslope side of the barrier as aresult of turbulent mixing of air layers as thecold air flows over it. Try to locate such barri-ers as close to the unit as possible.

Another design suggestion is to plant fast-growing evergreen trees which have goodwindbreak properties in buffer-zones around aunit. In addition to dispersing odors, denseplantings of evergreen trees will also help toprotect the unit itself from strong winds, reduc-ing the possibility of windblown soil erosion.

How can disease vectors be

controlled?

Disease vectors are animals or insects, suchas rodents, birds, flies, and mosquitos, thatcan transmit disease to humans. Burrowinganimals, such as gophers, moles, and ground-hogs, can also damage vital unit structures,such as liners, final cover materials, drainageditches, and sedimentation ponds. As a result,these animals can create costly problems.

Consider the following methods to controldisease vectors:

• Apply adequate daily cover. This sim-ple action is often all that is neededto control many disease vectors.

• Make sure the unit is properlydrained, reducing the amount ofstanding water that acts as a breedingmedium for insects.

• As a last resort, or when the applica-tion of cover material is impractical,consider using repellents, insecticides,rodenticides, or pest reproductive con-trol. Care must be taken to make surethat pesticides are used only in accor-dance with specified uses and applica-tion methods. Follow the instructionscarefully when using these products.Trapping animals might also be con-sidered, but trapping alone rarelyeliminates the problem.

If land applying wastes, subsurface injectionand prompt incorporation of waste can helpcontrol vectors. Both of these methods workby using the soil as a barrier between thewaste and the vectors. If a waste storage facili-ty exists, these can attract vectors as well andshould not be overlooked in the implementa-tion of vector control. If vector problems arise


8-19

■■■■ Develop a waste management system identifying the standard procedures necessaryfor a unit to operate according to its design throughout the intended working life.

■■■■ Provide proper maintenance and operation of ground-water, surface-water, and aircontrols.

■■■■ Develop daily procedures to place waste, operate environmental controls, and inspectand maintain the unit.

■■■■ Review at a regular interval, such as annually, whether the waste management systemneeds to be updated.

■■■■ Develop a waste analysis procedure to ensure an understanding of the physical andchemical composition of the waste to be managed.

■■■■ Develop regular schedules for waste screening and for unit inspections.

■■■■ If daily cover is recommended, select an appropriate daily cover and establishprocesses for placing and covering waste.

■■■■ Consider how operations can be affected by climate conditions.

■■■■ Implement security measures to prevent unauthorized entry.

■■■■ Provide personnel with proper training.

■■■■ Establish emergency response procedures and familiarize employees with emergencyequipment.

■■■■ Develop procedures for maintaining records.

■■■■ Establish nuisance controls to minimize dust, noise, odor, and disease vectors.

Operating the Waste ManagementSystem Activity List

8-20



8-21

ASTM. 1993. Standard Practice for Maintaining Health and Safety Records at Solid Waste Processing Facilities.E 1076-85.


Bolton, N. 1995. The Handbook of Landfill Operations: A Practical Guide for Landfill Engineers, Owners, andOperators. Blue Ridge Solid Waste Consulting.

Robinson, W. 1986. The Solid Waste Handbook: A Practical Guide. John Wiley & Sons Inc.

U.S. EPA. 1997. ISO 14000 Resource Directory. EPA625-R-97-003.

U.S. EPA/National Response Team. 1996. The National Response Teams Integrated Contingency PlanGuidance; Notice. (61 FR 28642; June 5, 1996).

U.S. EPA. 1998. CAMEO: Computer-Aided Management of Emergency Operations. EPA550-F-98-003.

U.S. EPA. 1995. Decision-Maker’s Guide to Solid Waste Management, Second Edition. EPA530-R-95-023.

U.S. EPA. 1995. State Requirements for Industrial Nonhazardous Waste Management Facilities.

U.S. EPA. 1994. Seminar Publication: Design, Operation, and Closure of Municipal Solid Waste Landfills.EPA625-R-94-008.

U.S. EPA. 1993. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.

U.S. EPA. 1991. Technical Resource Document: Design, Construction, and Operation of Hazardous andNonhazardous Waste Surface Impoundments. EPA530-SW-91-054.

U.S. EPA. 1989. Test Methods for Evaluating Solid Waste, Physical/Chemical Methods. SW-846.

U.S. EPA. 1988. RCRA Inspection Manual. OSWER Directive 9938.2A.

U.S. EPA. 1988. Subtitle D of RCRA, “Criteria for Municipal Solid Waste Landfills” (40 CFR Part 258),Operating Criteria (Subpart C). Draft/Background Document.

Resources


Chapter 9Monitoring Performance

Contents

I. Ground-Water Monitoring ......................................................................................................................9 - 2

A. Hydrogeological Characterization ..........................................................................................................9 - 2

B. Monitoring Methods ..............................................................................................................................9 - 4

1. Conventional Monitoring Wells ........................................................................................................9 - 4

2. Direct-Push Ground-Water Sampling ................................................................................................9 - 4

3. Geophysical Methods ........................................................................................................................9 - 5

C. Number of Wells....................................................................................................................................9 - 6

D. Lateral and Vertical Placement of Wells..................................................................................................9 - 7

1. Lateral Placement ..............................................................................................................................9 - 7

2. Vertical Placement and Screen Lengths ..............................................................................................9 - 8

E. Monitoring Well Design, Installation, and Development ........................................................................9 - 9

1. Well Design ......................................................................................................................................9 - 9

2. Well Installation ..............................................................................................................................9 - 12

3. Well Development ..........................................................................................................................9 - 12

F. Duration and Frequency of Monitoring ..............................................................................................9 - 13

G. Sampling Parameters............................................................................................................................9 - 13

H.Potential Modifications to a Basic Ground-Water Monitoring Program ................................................9 - 14

1. Duration and Frequency of Monitoring ..........................................................................................9 - 14

2. Sampling Parameters ......................................................................................................................9 - 16

3. Vadose-Zone Monitoring..................................................................................................................9 - 16

II. Surface-Water Monitoring ....................................................................................................................9 - 21

A. Monitoring Storm-Water Discharges ....................................................................................................9 - 22

B. Monitoring Discharges to POTWs........................................................................................................9 - 25

C. Monitoring Surface Water Conditions..................................................................................................9 - 26

III. Soil Monitoring ....................................................................................................................................9 - 28

A. Determining the Quality of Soil ..........................................................................................................9 - 29

B. Sampling Location and Frequency ......................................................................................................9 - 30

C. Sampling Equipment ..........................................................................................................................9 - 31

D. Sample Collection................................................................................................................................9 - 31

IV. Air Monitoring ......................................................................................................................................9 - 32

A. Types of Air Emissions Monitoring ......................................................................................................9 - 33

1. Emissions Monitoring......................................................................................................................9 - 33

2. Ambient Monitoring ........................................................................................................................9 - 33

3. Fugitive Monitoring ........................................................................................................................9 - 34

4. Meteorological Monitoring ..............................................................................................................9 - 34

B. Air Monitoring and Sampling Equipment ............................................................................................9 - 36

1. Ambient Air Monitoring ..................................................................................................................9 - 36

2. Source Emissions Monitoring ..........................................................................................................9 - 37

C. Test Method Selection..........................................................................................................................9 - 38

D. Sampling Site Selection........................................................................................................................9 - 38

V. Sampling and Analytical Protocols and Quality Assurance and Quality Control ..................................9 - 39

A. Data Quality Objectives ......................................................................................................................9 - 41

B. Sample Collection................................................................................................................................9 - 41

C. Sample Preservation and Handling ......................................................................................................9 - 42

D. Quality Assurance and Quality Control ..............................................................................................9 - 42

E. Analytical Protocols ............................................................................................................................9 - 44

VI. Analysis of Monitoring Data, Contingency Planning, and Assessment Monitoring................................9 - 45

A. Statistical Approaches ..........................................................................................................................9 - 45

B. Contingency Planning..........................................................................................................................9 - 46

C. Assessment Monitoring ........................................................................................................................9 - 46

Monitoring Performance Activity List ..........................................................................................................9 - 48

Resources ..................................................................................................................................................9 - 50

Tables:

Table 1: Factors Affecting Number of Wells Per Location ..........................................................................9 - 9

Table 2: Potential Parameters for Basic Groundwater Monitoring ............................................................9 - 15

Table 3: Recommended Components of a Basic Ground-Water Monitoring Program ..............................9 - 16

Table 4: Comparison of Manual and Automatic Sampling Techniques ....................................................9 - 24

Table 5: Types of QA/QC Samples............................................................................................................9 - 43

Figures:

Figure 1: Cross-Section of a Generic Monitoring Well................................................................................9 - 5

Figure 2: Major Methods for In Situ Monitoring of Soil Moisture or Matrix Potential ..............................9 - 18

Figure 3: Example Methods for Collecting Soil-Pore Samples ..................................................................9 - 19

Figure 4: Soil Gas Sampling Systems........................................................................................................9 - 20

Figure 5: Schematic Diagram of various Types of Sampling Systems ........................................................9 - 36

Figure 6: Sampling Train..........................................................................................................................9 - 38

Contents

Ensuring Long-Term Protection—Monitoring Performance

9-1

Monitoring the performance ofa waste management unit isan integral part of a compre-hensive waste managementsystem. A properly imple-

mented monitoring program provides anindication of whether a waste managementunit is functioning in accordance with itsdesign, and detects any changes in the quality

of the environment caused by the unit. Thedetection information obtained from a moni-toring program can be used to ensure that theproper types of wastes are being managed inthe unit, discover and repair any damagedarea(s) of the unit, and determine if an alter-native management approach might beappropriate. By implementing a monitoringprogram, facility managers can identify prob-lems or releases in a timely fashion and takethe appropriate measures to limit contamina-tion. Continued detection of contaminationin the environment could result in the imple-mentation of more aggressive correctiveaction measures to remediate releases.

This chapter highlights issues associatedwith establishing a ground-water monitoringprogram because most industrial waste man-agement units need to have such a program.The chapter also provides a discussion of air,surface water, and soil monitoring that mightbe applicable to some units managing industri-al waste. You should consult with qualifiedprofessionals, such as engineers and ground-water specialists,1 for technical assistance inmaking decisions about the design and opera-tion of a ground-water monitoring program. In

1 For the purpose of this chapter, a qualified “ground-water specialist” refers to a scientist or engineerwho has received a baccalaureate or post-graduate degree in the natural sciences or engineering and hassufficient training and experience in ground-water hydrology and related fields as demonstrated bystate registration, professional certifications, or completion of accredited university programs thatenable that individual to make sound professional judgements regarding ground-water monitoring,contaminant fate and transport, and corrective action.

Monitoring PerformanceThis chapter will help you:

• Carefully design and implement a monitoring program that is essen-

tial to evaluating whether a unit meets performance objectives and

whether there are releases to, and impacts on, the surrounding

environment that need to be corrected.

• Design effective monitoring programs that protect the environment,

improve unit performance, and help reduce long-term costs and lia-

bilities associated with industrial waste management.

This chapter will address the followingquestions.

• What site characterizations are needed todevelop an effective monitoring program?

• What are the basic elements of a moni-toring program?

• How should sampling and analytical pro-tocols be used in a monitoring program?

• What procedures should be used toevaluate monitoring data?

• What elements of the basic monitoringprogram can be modified to addresssite conditions?

9-2


addition when questions arise concerning soil,air, or surface-water monitoring, you shouldalso consult specialists in these areas as eachmedia requires different expertise.

I. Ground-WaterMonitoring

The basic elements of a ground-watermonitoring program include:

• The monitoring method.

• The number of wells.

• Location and screened intervals ofwells.

• Well design, installation, and devel-opment.

• The duration and frequency of moni-toring.

• Sampling parameters to be monitored.

The remainder of this section provides abrief overview of the six basic elements of aground-water monitoring program, alongwith a discussion of the importance of ahydrogeological characterization.

A. HydrogeologicalCharacterization

An accurate hydrogeological characteriza-tion is the foundation of an effective ground-water monitoring system. The goal of ahydrogeological characterization is to acquiresite-specific data to enable the developmentof an appropriate ground-water monitoringprogram for a site. In some instances, a com-plete hydrogeological characterization mightnot be necessary due to the type of unitbeing considered, the type of waste beingmanaged, or the climate. The design of theground-water monitoring program should bebased upon the following site-specific data:

• The lateral and vertical extent of theuppermost aquifer.

• The lateral and vertical extent of theupper and lower confining units/layers.

• The geology at the waste manage-ment unit’s site, such as stratigraphy,lithology, and structural setting.

• The chemical properties of the upper-most aquifer and its confining layers

Why is it important to usea qualified professional?• Site characterizations can be extremely

complex.

• Incorrect or incomplete characteriza-tions could result in inaccurate detec-tion of contamination in the groundwater due to improper placement ofground-water monitoring wells and cancost a significant amount of money.Incorrect or incomplete characteriza-tions could also result in the installationof unnecessary monitoring wells at sig-nificant cost.

• You should always use a qualified pro-fessional to conduct site characteriza-tions. Check to see if the professionalhas sufficient training and experience inground-water hydrology and relatedfields, as demonstrated by state registra-tion, professional certification, or com-pletion of accredited universityprograms. These professionals shouldbe experienced at analyzing ground-water flow and contaminant fate andtransport and at designing ground-water monitoring systems. Ensure thatthese professionals are familiar with thecontaminants in the waste and thor-oughly check their references.

relative to local ground-water chem-istry and wastes managed at the unit.

• Ground-water flow, including:

- The vertical and horizontal direc-tions of ground-water flow in theuppermost aquifer.

- The vertical and horizontal compo-nents of the hydraulic gradient inthe uppermost aquifer and anyhydraulically connected aquifer.

- The hydraulic conductivities of thematerials that comprise the uppermostaquifer and its confining units/layers.

- The average linear horizontal veloci-ty of ground-water flow in theuppermost aquifer.

To perform a hydrogeological characteriza-tion and develop an understanding of a site’shydrogeology, a variety of sources and kindsof information should be considered.

• Existing information. This caninclude the history of the site, includ-ing documented records describingwastes managed on site and releases.This information can help you char-acterize the area of the waste manage-ment unit and better understandbackground conditions. Some hydro-geological information might alsohave been developed in the past, forexample during the siting process(see Chapter 4–Considering the Site).It might be useful to conduct litera-ture reviews for research performedin the area of the unit and examinefederal and state geological and envi-ronmental reports related to the siteor to the region where the site is tobe located. This review can oftenassist in better understanding theoverall site geology and ground-waterflow beneath the unit.

• Site geology. A geologic unit is typi-cally considered to be any distinct ordefinable native rock or soil stratum.Characterize thickness, stratigraphy,lithology, and hydraulic characteris-tics of saturated and unsaturated geo-logic units and fill materials overlyingthe uppermost aquifer, in the upper-most aquifer, and in the lower con-fining unit of the uppermost aquiferusing soil borings, drilling, or geo-physical methods. Conventional soilborings are typically used to charac-terize onsite soils through direct sam-pling. Geophysical equipment, suchas ground-penetrating radar, electro-magnetic detection equipment, andelectrical resistivity arrays, can pro-vide non-invasive measurements ofphysical, electrical, or geochemicalproperties of the site. Understandingthe different strata can help identifythe appropriate ground-water moni-toring well locations and screendepths.

• Ground-water flow beneath thesite. Across the United States,ground-water flow velocities rangefrom several feet to over 2,000 feetper year. To determine hydraulic gra-dient and flow rate, you shouldimplement a water-level monitoringprogram and estimate hydraulic con-ductivity. This program shouldinclude measurements of seasonaland temporal fluctuations in flow, theeffect of site construction and opera-tions on ground-water flow direction,and variations in ground-water eleva-tion. Information on water-levelmonitoring programs and proceduresfor obtaining accurate water levelmeasurements can be found in EPA’sMunicipal Solid Waste Landfill TechnicalGuidance Document (U.S. EPA, 1988).


9-3

9-4


The level of effort one employs to character-ize a site sufficiently to design an adequateground-water monitoring system depends onthe geologic and hydrogeologic complexity ofthe site. The complexity of a site should not beassumed; a soil boring program can helpdetermine the complexity of a site’s hydrogeol-ogy. The American Society for Testing andMaterials’ (ASTM) Annual Book of ASTMStandards2 provides more than 80 guides andpractices related to waste and site characteriza-tion and sampling. For additional informationon ground-water monitoring, see EPA’sGround-Water Monitoring: Draft TechnicalGuidance (U.S. EPA, 1993a) and Solid WasteDisposal Facility Criteria: Technical Manual (U.S.EPA, 1993b).

B. Monitoring MethodsGround-water monitoring usually involves

the installation of permanent monitoring wellsfor periodic collection of ground-water sam-ples. Waste constituent migration can be mon-itored by sampling ground water for eithercontaminants or geophysical parameters.Ground water also can be sampled throughsemi-permanent conventional monitoringwells or by temporary direct-push sampling.Conventional monitoring wells, direct-pushsampling, and geophysical methods aredescribed below.

1. Conventional Monitoring WellsThe conventional monitoring well is the

most common type used to target a singlescreened interval. Figure 1 presents an illustra-tion of a single screened interval. Specific con-struction features are described in more detailbelow. The conventional monitoring well issemi-permanent, meaning it can be used forsampling over an extended period of time andshould be located by professionally surveyedreference points. To monitor more than one

depth at a single location, you should installconventional monitoring wells in clusters orwith multilevel sampling devices.

2. Direct-Push Ground-WaterSampling

Using the direct-push technique, groundwater is sampled by hydraulically pressingand/or vibrating a probe to the desired depthand retrieving a ground-water sample throughthe probe. The probe is removed for reuseelsewhere after the desired volume of groundwater is extracted. It is important to clean theprobe with an appropriate decontaminationprotocol after each use to avoid potentialcross-contamination.

What are the benefits of direct-

push sampling?

Given favorable geology, the direct-pushmethod of ground-water sampling can be asimpler and less expensive alternative to con-ventional wells. Conventional monitoringwells, because they are semi-permanent, gen-erally cost more and take longer to install.Direct-push technology, however, does notprovide a semi-permanent structure fromwhich to sample the ground water over anextended period of time, as do conventionalwells. Also, some states only allow the use ofdirect-push technology as an initial screeningtechnique or as a complement to conventionalmonitoring wells.

In sandy aquifers, however, the direct-pushtechnology can be used to install a well similarto a conventional monitoring well. Relativelyrecent advances in direct-push technology usepre-packed screens with grouts and sealsattached to a metal pipe that are driven intothe ground, forming an assembly similar to aconventional well. The appropriate stateagency will be able to tell you whether direct-push well installations are acceptable.

2 ASTM’s Annual Book of ASTM Standards is available in hard copy or on CD-ROM through ASTM’s onlinebookstore at <www.astm.org>.


9-5

3. Geophysical MethodsGeophysical methods measure potential

changes in ground-water quality by measur-ing changes in the geophysical characteristicsof the sub-surface soils, and in some cases, inthe ground water itself. For example, increas-

es in the levels of certain soluble metals inground water can change the resistive proper-ties of the ground water, which can be mea-sured using surface resistive technologies.Similarly, changes in the resistive propertiesof the vadose zone might indicate the migra-tion of leachate toward ground water.

Figure 1. Cross-Section of a Generic Monitoring Well

Source: U.S. EPA, 1993a

9-6


Geophysical characteristics, such as DC-resis-tivity, electromagnetic induction, pH, andtemperature, can provide important prelimi-nary indications of the performance of theliner system design. You should consult withthe appropriate state agency regarding theuse of a geophysical method. (See SubsurfaceCharacterization and Monitoring Techniques(U.S. EPA, 1993) for additional informationon the use of geophysical methods).

How useful is geophysical

method data?

Geophysical methods are more commonlyused to map the initial extent of contaminationat waste management units than for ongoingmonitoring. Initial monitoring data can guidethe placement of permanent monitoring wellsfor ongoing monitoring. As discussed later,geophysical methods, used in conjunction withground-water monitoring, can reduce the fre-quency of well sampling, which could reducemonitoring costs. The usefulness of geophysi-cal methods, however, will depend on the localhydrogeology, the contaminant concentrationlevels, and type of contaminants.

C. Number of WellsIt is recommended that a ground-water

monitoring system have a minimum of oneupgradient (or background) monitoring well,and three downgradient monitoring wells tomake statistically meaningful comparisons ofground-water quality. The upgradient orbackground well(s) permit the assessment ofthe background quality of onsite groundwater. The downgradient wells permit detec-tion of any contaminant plumes from a wastemanagement unit. The actual number ofupgradient and downgradient wells will varyfrom unit to unit depending on the actualsite-specific conditions. The actual number ofupgradient and downgradient monitoringwells and their distribution will influence the

selection of appropriate statistical method. Ifan insufficient number of background wellsare used, the use of an inter-well evaluationmight not be possible. Site-specific condi-tions that influence the number of upgradientand downgradient wells include:

• Geology of the waste managementunit site.

• Ground-water flow direction andvelocity, including seasonal and tem-poral fluctuations.

• Permeability or hydraulic conductivi-ty of any water-bearing formations.

• Physical and chemical characteristicsof contaminants.

• Area of waste management unit.

The number of wells is dependent on thelateral and vertical placement of monitoringwells, which is determined by the geologyand hydrogeology of the site. Other factorsinfluencing the number of wells include thenumber of potential contaminant migrationpathways; the spatial distribution of potentialcontaminant migration pathways; and thedepth and thickness of stratigraphic horizonsthat can serve as contaminant migrationpathways. The number of wells needed willalso vary according to the need for samplesfrom different depths in the aquifer. This is afunction of hydrogeologic factors and thechemical and physical characteristics of cont-aminants. The next section provides adetailed discussion of the lateral and verticalplacement of monitoring wells.

A larger number of monitoring wells mightbe needed at sites with complex hydrogeology.If a site has multiple waste management units,use of a multi-unit ground-water monitoringsystem can reduce the necessary number ofwells. You should consult with the appropriatestate agency when determining a site’s ground-water monitoring well requirements.


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D. Lateral and VerticalPlacement of Wells

The lateral and vertical placement of moni-toring wells is very site-specific. (Monitoringwells should yield ground-water samplesfrom the targeted aquifer(s) that are represen-tative of both the quality of backgroundground water and the quality of ground waterat a downgradient monitoring point.) Locatemonitoring wells at the closest practicabledistance from the waste management unitboundary to detect contaminants before theymigrate away from the unit. Early detectionprovides a warning of potential waste man-agement unit design failure and allows timeto implement appropriate abatement mea-sures and potentially eliminate the need formore extensive corrective action. It alsoreduces the area exposed and can limit over-all liability.

1. Lateral PlacementMonitoring wells should be placed laterally

along the down-gradient edge of the wastemanagement unit to intercept potential conta-minant migration pathways. Ground-waterflow direction and hydraulic gradient are twomajor determining factors in monitoring wellplacement. Placement of monitoring wellsshould also take into account the numberand spatial distribution of potential contami-nant migration pathways and the depths andthickness of stratigraphic horizons that canserve as contaminant migration pathways. Inhomogeneous, isotropic hydrogeologic sites,ground-water flow direction and hydraulicgradient, along with the potential contami-nant’s chemical and physical characteristics,will primarily determine lateral well place-ment. In a more complex site where hydroge-ology and geology are variable andpreferential pathways exist, (a heterogeneous,anisotropic hydrogeologic site, for example)the well placement determination becomes

more complex. Potential migration pathwaysare influenced by site geology includingchanges in hydraulic conductivity, fracturedor faulted zones, and soil chemistry. Human-made features that influence ground-waterflow should also be considered. These fea-tures include ditches, filled areas, buried pip-ing, buildings, leachate collection systems,and other adjacent disposal units.

Another point of consideration is seasonalchange in ground-water flow. Seasonalchanges in ground-water flow can result fromseasonal changes in precipitation patterns,tidal influences, lake or river stage fluctua-tions, well pumping, or land use patternchanges. At some sites it might even be possi-ble that ground water flows in all directionsfrom a waste management unit. These contin-gencies might call for placement of monitor-ing wells in a circular pattern to monitor onall sides of the waste management unit.Seasonal fluctuations might cause certainwells to be downgradient only part of thetime, but such configurations ensure thatreleases will be detected.

Lateral placement of monitoring wells alsodepends upon the chemical and physicalcharacteristics of a waste management unit’sconstituents. Consider potential contaminantcharacteristics such as solubility, Henry’s lawconstant, partition coefficients, specific gravity(density), potential for natural attenuation andthe resulting reaction or degradation products,and the potential for contaminants to degradeconfining layers. A dense non-aqueous phaseliquid (DNAPL), for instance, because of itsdensity might not necessarily migrate only inthe direction of the ground-water flow. Thepresence of DNAPLs, therefore, can result inplacing wells in more locations than just thenormal downgradient sites.

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2. Vertical Placement and ScreenLengths

Similar to lateral placement, vertical wellplacement in the ground water around awaste management unit is determined bygeologic and hydrogeologic factors, as well asthe chemical and physical characteristics ofthe potential contaminants. The verticalplacement of each well and its screen lengthswill be determined by the number and spatialdistribution of potential contaminant migra-tion pathways and the depth and thickness ofpotential migration pathways. Site-specificgeology, hydrogeology, and constituent char-acteristics influence the location, size, andgeometry of potential contaminant plumes,which in turn determine monitoring welldepths and screen lengths.

The chemical and physical characteristicsof potential contaminants from a waste man-agement unit play a significant role in deter-mining vertical placement. The specificproperties of a particular contaminant willdetermine what potential migration pathwayit might take in an aquifer. The specific char-acteristics of a contaminant, such as its solu-bility, Henry’s law constant, partitioncoefficients, specific gravity (density), poten-tial for natural attenuation and the resultingreaction or degradation products, and thepotential for contaminants to degrade confin-ing layers, will all influence the vertical place-ment and screen lengths of a unit’smonitoring wells. A DNAPL, for instance, willsink to the bottom of an aquifer and migratealong geologic gradients (rather than hydro-geologic gradients), thus a monitoring well’svertical placement should correspond withthe depth of the appropriate geologic feature.LNAPLs (light non-aqueous phase liquids),on the other hand, would move along the topof an aquifer, and result in placement of wellsand wells screens at the surface of the aquifer.

Well screen lengths are also determined bysite- and constituent-specific parameters.These parameters and the importance of tak-ing vertically discrete ground-water samples,factor into the determination of well screensize. Highly heterogeneous (complex) geolog-ic sites require shorter well screen lengths toallow for the sampling of discrete migrationpathway. Screens that span more than a singlecontaminant migration pathway can causecross contamination, possibly increasing theextent of contamination. Shorter screenlengths allow for more precise monitoring ofthe aquifer or the portion of the aquifer ofconcern. Excessively large well screens canlead to the dilution of samples making conta-minant detection more difficult.

The depth or thickness of an aquifer alsoinfluences the length of the well screen. Siteswith highly complex geology or relativelythick aquifers might require multiple screensat varying depths. Conversely, a relativelythin and homogenous aquifer might allow forfewer wells with longer screen lengths. Table1 below summarizes the recommended fac-tors to consider when determining the num-ber of wells needed per sampling location.

You should consult with state officials onthe lateral and vertical placement of monitor-ing wells including well screening lengths. Inthe absence of specific state requirements, itis recommended that the monitoring pointsbe no more than 150 meters downgradientfrom a waste management unit boundary, onfacility property, and placed in potential cont-amination migration pathways. This maxi-mum distance is consistent with the approachtaken in many states in order to protectwaters of the state.


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E. Monitoring Well Design,Installation, andDevelopment

Ground-water monitoring wells are tai-lored to suit the hydrogeologic setting, thetype of constituents to be monitored, theoverall purpose of the monitoring program,and other site-specific variables. You shouldconsult with the appropriate state agency andqualified professionals to discuss the designspecifications for ground-water monitoringwells before beginning construction. Figure 1illustrates the design components that are dis-cussed in this section. The Annual Book ofASTM Standards includes guides and practicesrelated to monitoring well design, construc-tion, development, maintenance, and decom-missioning. EPA’s Handbook of SuggestedPractices for the Design and Installation of

Ground-Water Monitoring Wells (U.S. EPA,1989) also contains this information.

1. Well DesignThe typical

components of amonitoring wellinclude a wellcasing, a wellintake, a filterpack, an annularand surface seal,and surface com-pletion. Each ofthese compo-nents is brieflydescribed below.

One Well per Sampling Location More Than One Well Per Sampling Location

No light non-aqueous phase liquids Presence of LNAPLs or DNAPLs(LNAPLs) or dense non-aqueous phaseliquids (DNAPLs) (immiscible liquidphases)

Thin flow zone (relative to screen Thick flow zoneslength) Vertical gradients present

Horizontal flow predominates

Homogeneous isotropic uppermost Heterogeneous anisotropic uppermost aquifier, aquifier, simple geology complicated geology

- multiple, interconnected aquifiers- variable lithology- perched water zones- discontinuous structures

Discrete fracture zones in bedrock Solution conduits, such as caves, in karst terrains Cavernous basalts

Table 1Factors Affecting Number of Wells Per Location (CLUSTER)

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3 A piezometer is a non-pumping well, generally of small diameter, used to measure the elevation of thewater table.


Well Casing

The well casing is a pipe which is installedtemporarily or permanently to counteractcaving and to isolate the zone being moni-tored. The well casing provides access fromthe surface of the ground to some point inthe subsurface. The casing, associated seals,and grout prevent borehole collapse andinterzonal hydraulic communication. Accessto the monitored zone is through the casingand either the screened intake or the openborehole. (Note: some states do not allow theuse of open borehole monitoring wells.Check with the state agency to determinewhether this type of monitoring well designis acceptable.) The casing thus permits piezo-metric head measurements and ground-waterquality sampling.

A well casing can be made of an appropri-ate rigid tubular material. The most frequentlyevaluated characteristics that directly influencethe performance of casing material in ground-water monitoring applications are strength,chemical resistance, and interference. Themonitoring well casing should be strongenough to resist the forces exerted on it by thesurrounding geologic materials and the forcesimposed on it during installation. Casingsshould exhibit structural integrity for theexpected duration of the monitoring programunder natural and man-induced subsurfaceconditions. Well casing materials should alsobe durable enough to withstand galvanic orelectrochemical corrosion and chemical degra-dation. Metallic casing materials are most sub-ject to corrosion and thermoplastic casingmaterials are most subject to chemical degra-dation. In addition, casing materials shouldnot exhibit a tendency to either sorb chemicalconstituents from (i.e., take constituents outof solution by either adsorption or absorption)or leach chemical constituents into the waterthat is sampled from the well. If casing mate-rials sorb selected constituents, the water-quality sample will not be representative.

The three most common types of casingmaterials are fluoropolymer materials, includ-ing polytetrafluoroethylene (PTFE) and tetra-fluoroethylene (TFE); metallic materials,including carbon steel, galvanized steel, andstainless steel; and thermoplastic materials,including polyvinyl chloride (PVC) and acry-lonitrile butadiene styrene (ABS). Threaded,flush casing joints that do not require glueshould be used. Another option is the use ofPTFE tape or o-rings at the threaded joints.

Well Screen

A well screen is a filtering device used toretain the primary or natural filter pack; it isusually a cylindrical pipe with openings of auniform width, orientation, and spacing. It isoften important to design the monitoring wellwith a well intake (well screen) placed oppo-site the zone to be monitored. The intakeshould be surrounded by materials that arecoarser, have a uniform grain size, and have ahigher permeability than natural formationmaterial. This allows ground water to flowfreely into the well from the adjacent forma-tion material while minimizing or eliminatingthe entrance of fine-grained materials, such asclay or sand, into the well.

A well screen design should consider:intake opening (slot) size, intake length,intake type, and corrosion and chemical-degradation resistance. Proper sizing of moni-toring well intake openings is one of the mostimportant aspects of monitoring well design.The selection of the length of a monitoringwell intake depends on the purpose of thewell. Most monitoring wells function as bothground-water sampling points and piezome-ters3 for a discrete interval. To accomplishthese objectives, well intakes are typically 2to 10 feet in length and only rarely equal orexceed 20 feet in length. The hydraulic effi-ciency of a well intake depends primarily onthe amount of open area available per unitlength of intake. The amount of open area in

a well intake is controlled by the type of wellintake it is and its opening size. Many typesof well intakes have been used in monitoringwells, including: the louvered (shutter-type)intake, the bridge-slot intake, the machine-slotted well casing, and the continuous-slotwire-wound intake.

Filter Pack

Filter pack is the material placed betweenthe well screen and the borehole wall thatallows ground water to flow freely into thewell while filtering out fine-grained materials.It is important to minimize the distortion ofthe natural stratigraphic setting during con-struction of a monitoring well. Hence, itmight be necessary to filter-pack boreholesthat are over-sized with regard to the casingand well intake diameter. The filter pack pre-vents formation material from entering thewell intake and helps stabilize the adjacentformation. The filter-pack materials should bechemically inert to avoid the potential foralteration of ground-water sample quality.Commonly used filter-pack materials includeclean quartz sand, gravel, and glass beads.You should check with the state regulatoryagency to determine if state regulations speci-fy filter pack grain size, either in absoluteterms or relative to the grain size of the waterbearing zone, or a uniformity coefficient.

The filter pack should generally extendfrom the bottom of the well intake to approx-imately two to five feet above the top of thewell intake, provided the interval above thewell intake does not result in a hydraulicconnection with an overlying zone. To ensurethat filter pack material completely surroundsthe screen and casing without bridging, thefilter pack can be placed with a tremie pipe (asmall diameter pipe that carries the filterpack material directly to the filter screenwithout creating air pockets within the filterpack). A layer of fine sand can also be placed

on top of the filter pack to minimize migra-tion of annular seal material (see below) intothe filter pack.

Annular Seal

Annular space is the space between thecasing and the borehole wall. Any annularspace that is produced as a result of theinstallation of well casing in a borehole pro-vides a channel for vertical movement ofwater and/or contaminants unless the space issealed. The annular seal in a monitoring wellis placed above the filter pack in the annulusbetween the borehole and the well casing.The seal serves several purposes: to provideprotection against infiltration of surface waterand potential contaminants from the groundsurface down the casing/borehole annulus; toseal off discrete sampling zones, bothhydraulically and chemically; and to prohibitvertical migration of water. Such verticalmovement can cause “cross contamination”which can influence the representativeness ofground-water samples. The annular seal canbe comprised of several different types of per-manent, stable, low-permeability materialsincluding pelletized, granular, or powderedbentonite; neat cement grout; and combina-tions of both. The most effective seals areobtained by using expanding materials thatwill not shrink away from either the casing orthe borehole wall after curing or setting.

Surface Seal

A surface seal is an above-ground seal thatprotects a monitoring well from surface waterand contaminant infiltration. Monitoring wellsshould have a surface seal of neat cement orconcrete surrounding the well casing and fill-ing the annular space between the casing andthe borehole at the surface. The surface sealcan be an extension of the annular sealinstalled above the filter pack, or it can be aseparate seal placed on top of the annular


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seal. The surface seal will generally extend toat least three feet away from the well casing atthe surface and taper down to the size of theborehole within a few feet of the surface. Inclimates with alternating freezing and thawingconditions, the cement surface should extendbelow the frost depth to prevent potential welldamage caused by frost heaving.

Surface Completions

Surface completions are protective casingsinstalled around the well casing. Two types ofsurface completions are common for ground-water monitoring wells: above-ground com-pletion, and flush-toground completion.The primary purposes of either type of com-pletion are to prevent surface runoff fromentering and infiltrating down the annulus ofthe well and to protect the well from acciden-tal damage or vandalism.

In an above-ground completion, which isthe preferred alternative, a protective casing isgenerally installed around the well casing byplacing the protective casing into the cementsurface seal while it is still wet and uncured.The protective casing discourages unautho-rized entry into the well, prevents damage bycontact with vehicles, and reduces degrada-tion caused by direct exposure to sunlight.The protective casing should be fitted with alocking cap and installed so that there are atleast one to two inches clearance between thetop of the in-place, inner well, casing cap andthe bottom of the protective casing lockingcap when in the locked position.

Like the inner well casing, the outer pro-tective casing should be vented near the topto prevent the accumulation and entrapmentof potentially explosive gases and to allowwater levels in the well to respond naturallyto barometric pressure changes. Additionally,the outer protective casing should have adrain hole installed just above the top of thecement level in the space between the protec-

tive casing and the well casing. This drainallows trapped water to drain away from thecasing. In high-traffic areas or in areas whereheavy equipment might be working, considerthe installation of additional protection suchas “bumper guards.” Bumper guards arebrightly-painted posts of wood, steel, or someother durable material set in cement andlocated within three or four feet of the well.

2. Well InstallationTo ensure collection of representative

ground-water samples, the well intake, filterpack, and annular seal need to be properlyinstalled. In cohesive unconsolidated materialor consolidated formations, well intakesshould be installed as an integral part of thecasing string by lowering the entire unit intothe open borehole and placing the well intakeopposite the interval to be monitored.Centralizing devices are typically used to cen-ter the casing and intake in the borehole toallow uniform installation of the filter packmaterial around the well intake. In non-cohe-sive, unconsolidated materials there are otherstandardized techniques to ensure the properinstallation of wells, such as the use of a cas-ing hammer, a cable tool technique, the dual-wall reverse-circulation method, orinstallation through the hollow stem of a hol-low-stem auger.

3. Well DevelopmentMonitoring well development is the

removal of fine particulate matter, commonlyclay and silt, from the geologic formationnear the well intake. If particulate matter isnot removed, as water moves through the for-mation into the well, the water sampled willbe turbid, and the viability of the water quali-ty analyses will be impaired. When pumpingduring well development, the movement ofwater is unidirectional toward the well.Therefore, there is a tendency for the particu-

lates moving toward the well to “bridge”together or form blockages that restrict subse-quent particulate movement. These blockagescan prevent the complete development of thewell capacity. This effect potentially impactsthe quality of the water entering the well.Development techniques should remove suchbridges and encourage the movement of par-ticulates into the well. These particulates canthen be removed from the well by bailer orpump and, in most cases, the water producedwill subsequently be clear and non-turbid.

In most instances, monitoring wellsinstalled in consolidated formations can bedeveloped without great difficulty. Monitoringwells also can usually be developed rapidlyand without great difficulty in sand and grav-el deposits. However, many installations aremade in thin, silty, and/or clayey zones. It isnot uncommon for these zones to be difficultto develop sufficiently for adequate samplesto be collected.

F. Duration and Frequencyof Monitoring

The duration of ground-water monitoringwill depend on the length of the active life ofthe waste management unit and its post-clo-sure care period. Continued monitoring aftera waste management unit has closed isimportant because the potential for contami-nant releases remains even after a unit hasstopped receiving waste. Monitoring frequen-cy should be sufficient to allow detection ofground-water contamination. This frequencyusually ranges from quarterly to annually.

What site characteristics should

be evaluated to determine the

frequency of monitoring?

Ground-water flow velocity is important inestablishing an appropriate ground-water

monitoring frequency to ensure that samplescollected are physically and statistically inde-pendent. For example, in areas with highground-water flow velocity, more frequentmonitoring might be necessary to detect arelease before it migrates and contaminateslarge areas. In areas with low flow velocity,less frequent monitoring might be appropri-ate. It is important to analyze backgroundground-water conditions, such as flow direc-tion, velocity, and seasonal fluctuations tohelp determine a suitable monitoring fre-quency for a site. You should consult with theappropriate state agency to determine anappropriate monitoring frequency. In theabsence of state requirements, it is recom-mended that semi-annual monitoring be con-ducted to detect contamination as part of abasic monitoring program.

G. Sampling ParametersSelection of parameters to be monitored in a

ground-water monitoring program should bebased on the characteristics of waste in themanagement unit. Additional sampling andanalysis information can be found in EPA SW-846 Test Methods for Evaluating Solid Waste (U.S.EPA, 1986) and in ASTM’s standards. TheAnnual Book of ASTM Standards also identifies18 ASTM guides and practices for performingwaste characterization and sampling.

What are sampling parameters?

Analyzing a large number of ground-waterquality parameters in each sampling episodecan be costly. To minimize expense, selectonly contaminants and geochemical indicatorsthat can be reasonably expected to migrate tothe ground water. These are called samplingparameters. Sampling parameters should pro-vide an early indication of a release from awaste management unit. Once contaminationis detected, consider expanding the original


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sampling parameters and monitor for addi-tional constituents to fully characterize thechemical makeup of the release.

What sampling parameters

should be used?

Due to the broad universe of industrialsolid waste, it is not possible to recommend alist of indicator papameters that are capableof identifying every possible release. It is rec-ommended to begin by analyzing for a broadrange of parameters to establish backgroundground-water quality, and then use the resultsto select the sampling parameters to be moni-tored subsequently at a site. Table 2 listspotential parameters for a basic ground-watermonitoring program, by different categories.Modify these parameters, as appropriate, toaddress site-specific circumstances. Yourknowledge of the actual waste streams orexisting analytical data is a preliminary guidefor what should be monitored, and leachatesampling data is also useful to select or adjustsampling parameters. Where there is uncer-tainty concerning the chemistry of the waste,you should perform metal and organic scansat a minimum. You should consult with theappropriate state agency to ensure that appro-priate sampling parameters are selected.

What are the minimum

components of a basic

monitoring program?

Table 3 summarizes the recommendedminimum components of a basic ground-water monitoring program described above.Potential modifications to the basic monitor-ing program that might be appropriate basedon site-specific waste management unit con-ditions are discussed later in this chapter.

H. Potential Modificationsto a Basic Ground-WaterMonitoring Program

It might be appropriate to modify certainelements of the basic ground-water monitoringprogram described above to accommodate site-specific circumstances. When using the IWEMsoftware to evaluate the need for a liner system,if the recommendation is to use a compositeliner, then the basic ground-water monitoringprogram should probably be enhanced. If therecommendation using the software is that noliner is appropriate, then it might be possible toscale back some aspects of the basic ground-water monitoring program.

Components that might be subject to mod-ification include the duration and frequencyof monitoring, sampling parameters, and theuse of vadose zone monitoring. Possible mod-ifications of these elements are discussed fur-ther below. You should consult with theappropriate state officials on their require-ments for ground-water monitoring programs.In some states, a unit might be eligible for ano-migration exemption from the state’sground-water monitoring requirements.

1. Duration and Frequency ofMonitoring

The duration of monitoring (active lifeplus post-closure care) is not likely to bemodified in either a reduced or an enhancedground-water monitoring program.Adjustments to the frequency of monitoring,however, might be appropriate, based primar-ily on the mobility of contaminants andground- water velocity. For example, if thesampling parameters are slow moving metals,annual rather than semi-annual monitoringmight be appropriate. Conversely, quarterlymonitoring might be considered at a unitwith a rapid ground-water flow rate or a

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Category Specific Parameters

Field-Measured Parameters TemperaturepHSpecific electrical conductanceDissolved oxygenEh oxidation-reduction potentialTurbidity

Leachate Indicators Total organic carbon (TOC-filtered)pHSpecific conductanceManganese (Mn)Iron (Fe)Ammonium (NH4)Chloride (Cl)Sodium (Na)Biochemical oxygen demand (BOD)Chemical oxygen demand (COD)Volatile organic compounds (VOCs)Total Halogenated Compounds (TOX)Total Petroleum Hydrocarbons (TPH)Total dissolved solids (TDS)

Additional Major Water Quality Parameters Bicarbonate (HCO3)Boron (Bo)Carbonate (CO3)Calcium (Ca)Fluoride (Fl)Magnesium (Mg)Nitrate (NO3)Nitrogen (disolved N2)Potassium (K)Sulfate (SO4)Silicon (H2SiO4)Strontium (Sr)Total dissolved solids (TDS)

Minor and Trace Inorganics Initial background sampling of inorganics for which drink-ing water standards exist (arsenic, barium, cadmium,chromium, lead, mercury, selenium, silver); ongoing moni-toring of any constituents showing background near orabove drinking water standards.

Waste-Specific Constituents Selected based on knowledge of waste characteristics (ini-tial metals and organic scans at a minimum).

Table 2Potential Parameters for Basic Ground-Water Monitoring

(Potential Parameters Should be Selected Based on Site-Specific Circumstances)

mobile contaminant such as cyanide over apermeable sand and gravel aquifer.

2. Sampling ParametersThe basic recommended ground-water

monitoring program already recommends theuse of a parameter list that is tailored to thewaste characteristics and site hydrogeology.Where the use of the IWEM software indi-cates no liner is appropriate, it might be pos-sible to reduce the list of parametersroutinely analyzed in downgradient wells toonly a few indicator parameters. More com-plete analysis would only be initiated if a sig-nificant change in the concentration of anindicator parameter had occurred.

3. Vadose-Zone MonitoringThe vadose zone is the region between the

ground surface and the saturated zone.Depending on climate, soils, and geology, it

can range in thickness from several feet tohundreds of feet. Vadose-zone monitoringcan detect migration of contaminants beforethey reach ground water, serving as an earlywarning system if a waste management unitis not functioning as designed. It can alsoreduce the time and cost of remediation, andthe extent of subsequent ground-water moni-toring efforts.

If site conditions permit, it might be desir-able to include vadose-zone monitoring aspart of the overall ground-water program. Ifvadose-zone monitoring is incorporated, therecommended number of ground-water mon-itoring wells would be determined by thebasic ground-water monitoring program, andbackground quality would still need to becharacterized with ground-water monitoring.The ground-water monitoring programbecomes a backup, however, with full useonly being initiated if contaminant migrationis detected in the vadose zone. The sections

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Monitoring Component Recommended Minimum

Number of Wells Minimum 1 upgradient and 3 downgradient.4

Point of Monitoring Waste management unit boundary or out to 150 metersdown gradient of the waste management unit area.5

Duration of Monitoring Active life plus post-closure care.

Frequency of Monitoring Semi-annual during active life.6

Sampling Parameters Metal and organic scans, use of indicators, leachate analysis,and/or knowledge of the waste. See the categories listed inTable 2.

Table 3 Recommended Components of a Basic Ground-Water Monitoring Program

4 The actual number of both upgradient and downgradient wells will vary from unit-to-unit and willdepend on the actual site-specific conditions.

5 Discussion of EPA’s rationale for the point of monitoring being out to 150 meters from a unit’s bound-ary can be found in 40 CFR Part 258 criteria.

6 Ground-water flow rate might dictate that more or less frequent monitoring might be appropriate. Morefrequent monitoring might be appropriate at the start of a monitoring program to establish background.Less frequent and/or reduced in scope monitoring might also be appropriate during the post-closurecare period.

below describe some of the commonly usedmethods for vadose zone monitoring, vadosezone characterization, and elements to con-sider in the design of a vadose zone monitor-ing system.

Vadose-Zone Monitoring Methods

There are dozens of specific techniques forindirect measurement and direct sampling ofthe vadose zone. The more commonly usedmethods with potential value for waste man-agement units are described briefly below.

Soil-Water and Tension Monitoring

Measuring changes over time in soil-watercontent or soil-water tension is a relativelysimple and inexpensive method for leakdetection. Periodic measurements of soil watercontent or soil moisture tension beneath alined waste management unit, for example,should show only small changes. Significantincreases in water content or decreases inmoisture tension would indicate a leak.

What method should be used to

measure soil moisture?

Soil-moisture characteristics can be mea-sured in two main ways: 1) water content,usually expressed as weight percentage, and2) soil-moisture tension, or suction, whichmeasures how strongly water is held by soilparticles due to capillary effects. As soil-watercontent increases, soil-moisture tensiondecreases. Measurements will not indicate,however, whether contaminants are present.

Figure 2 shows three major methods thatare available for insitu monitoring of soil-moisture changes. Porous-cup tensiometers(Figure 2a) measure soil-moisture tension,with the pressure measurements indicated byusing either a mercury manometer, a vacuumgauge, or pressure transducers. Soil-moistureresistivity sensors (Figure 2b) measure either

water content or soil-moisture tension,depending on how they are calibrated. Time-domain reflectometry probes (Figure 2c)measure water content using induced electro-magnetic currents. For vadose-zone monitor-ing applications, the devices are usuallyplaced during construction of a waste man-agement unit and electrical cables run to oneor more central locations for periodic mea-surement. The other commonly used methodfor monitoring soil-water content is to useneutron or dielectric probes. These requireplacement of access tubes, through whichprobes are lowered or pulled, and allow con-tinuous measurement of changes in watercontent along the length of the tubes.

Soil-Pore Liquid Sampling

Sampling and analysis of soil-pore liquidscan determine the type and concentration ofcontaminants that might be moving through thevadose zone. Soil-pore liquids can be collectedby applying either a vacuum that exceeds thesoil moisture tension, commonly done usingvacuum or pressure-vacuum lysimeters, or byburying collectors that intercept drain water.Figures 3a and 3b illustrate different methodsfor collecting soil-pore liquids.

Soil-Gas Sampling

Soil-gas sampling is a relatively easy andinexpensive way to detect the presence ormovement of volatile contaminants and gasesassociated with degradation of waste within a


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waste management unit, such as carbondioxide and methane. Of particular concernare gases associated with the breakdown oforganic materials and toxic organic com-pounds. Permanent soil-gas monitoringinstallations consist of a probe point placedabove the water table, a vacuum pump which

draws soil-gas to the surface, and a syringeused to extract the gas sample, as shown inFigure 4a. Installing soil-gas probes at multi-ple levels, as shown in Figure 4b, allowsdetection of downward or upward migrationof soil gases. It is important to note, however,that the performance of soil-gas sampling can

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Figure 2. Major Methods for In Situ Monitoring of Soil Moisture or Matrix Potential

(a) Three Types of Porous Cup Tensiometers, (b) Resistance Sensors, and (c) Time Domain ReflectometryProbes Sources: (a) Morrison, 1983. (b) U.S. EPA, 1993. (c) Topp and Davis, 1985, by permission.

be limited by some types of soil, such as tightclays or tight, saturated clays.

Vadose Zone Characterization

Just as the design of ground-water moni-toring systems requires an understanding ofthe ground-water flow system, the design ofvadose zone monitoring systems requires anunderstanding of the vadose zone flow sys-tem. For example, in ground water systems,hydraulic conductivity does not change overtime at a particular-location, whereas in thevadose zone, hydraulic conductivity changeswith soil-water content and soil-moisture ten-sion. To estimate the speed with which waterwill move through the vadose zone, the rela-tionship between soil-water content, soil-

moisture tension, and hydraulic conductivityshould be measured or estimated.Unsaturated zone numerical modeling pro-grams, such as HYDRUS 2-D or Seep (2-D)are designed to characterize the vadose zone.

Vadose-Zone Monitoring System Design

A vadose zone monitoring system com-bined with a ground-water monitoring sys-tem can reduce the cost of correctivemeasures in the event of a release. Remedialaction is usually easier and less expensive ifemployed before contaminants reach theground-water flow system.

The design and installation of a vadose-zonemonitoring system are easiest with new waste


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Figure 3. Example Methods for Collecting Soil-Pore Samples

(a) Vacuum Lysimeter, (b) Pressure-Vacuum LysimeterSource: ASTM, 1994. Copyright ASTM. Reprinted with permission.

management facilities, where soil-water moni-toring and sampling devices can be placedbelow the site. Relatively recent improvementsin horizontal drilling technology, however, nowallow installation of access tubes for soil-mois-ture monitoring beneath existing facilities.Important factors in choosing the location anddepth of monitoring points in a leak-detection

network include: 1) consideration of thepotential area of downward leakage, and 2)determination of the effective detection area ofthe monitoring device.

Cullen et al. (1995) suggest an approachto vadose zone monitoring that includes thefollowing:

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Figure 4. Soil Gas Sampling Systems

(a) Gas Sampling Probe and Sample Collection Systems, (b) Typical Installation of Nested Soil Gas Probes Source: Reprinted with permission from Wilson, et al., Handbook of Vadose Zone Characterization andMonitoring, 1995. Copyright CRC Press, Boca Raton, Florida.

• Identification and prioritization ofcritical areas most vulnerable to cont-aminant migration.

• Selection of indirect monitoringmethods that provide reasonablycomprehensive coverage and cost-effective, early warning of contami-nant migration.

• Selection of direct monitoring meth-ods that provide diagnostic confirma-tion of the presence and migration ofcontaminants.

• Identification of background moni-toring points that will provide hydro-geologic monitoring datarepresentative of preexisting site con-ditions.

• Identification of a cost-efficient, tem-poral monitoring plan that will pro-vide early warning of contaminantmigration in the vadose zone.

This approach is very similar to what isdescribed for the basic ground-water moni-toring program.

II. Surface-WaterMonitoring

Controlling constituent discharges to sur-face water from industrial waste managementunits is another component of responsiblewaste management. Monitoring can be con-ducted for many purposes, such as:

• Characterizing surface-water condi-tions and identifying changes ortrends in water quality over time.

• Identifying existing or emergingwater quality problems.

• Identifying the types and amounts ofconstituents present in the water body.

• Designing a pollution prevention pro-gram or establishing best manage-ment practices (BMPs).

• Determining whether surface-waterregulations and permit conditions arebeing satisfied.

• Responding to emergencies, such asaccidental discharges or spills.

Some types of monitoring activities meetseveral of these purposes simultaneously,while others are specifically designed for onepurpose, such as to determine compliancewith permit conditions.

If your facility is subject to a federal, state,or local permit that requires monitoring andsampling, you must collect and analyze sam-ples according to the permit requirements.Otherwise, you should consider implement-ing a sampling program to monitor the quali-ty of runoff, the performance of BMPs, andany impacts on surface waters. For furtherinformation on BMPs relating to surface-water quality, refer to Chapter 6–ProtectingSurface Water. Implementation of BMPs,along with regular maintenance inspectionsand upkeep, will greatly reduce the potentialfor surface-water contamination.

When establishing any type of samplingand monitoring program, there are certaincommon sense guidelines to follow.Inadequate frequency of data collection andincomplete monitoring might be uselesswhile high-frequency monitoring and sam-pling for numerous constituents can be costlyand could create a backlog of unusable data.The following discussion summarizes whatyou should consider when establishing sam-pling programs to effectively perform surfacewater monitoring.


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A. Monitoring Storm-WaterDischarges

As discussed in Chapter 6–ProtectingSurface Water, NPDES permits establish lim-its on what constituents (and at whatamounts or concentrations) facilities may dis-charge to receiving surface waters. Somewaste management units, such as surfaceimpoundments, might have an NPDES per-mit to discharge wastewaters directly to sur-face waters. Other units might need anNPDES permit for storm-water discharges.An NPDES permit will also contain limits onwhat can be discharged, monitoring andreporting requirements, and other provisionsto ensure that the discharge does not impairsurface-water quality or human health. Dueto the variable nature of storm-water flowsduring a rainfall event and the different ana-lytical considerations for certain constituents,the sampling requirements for different wastemanagement unit types and sampling loca-tions will vary as well. The guidelines andgeneral sampling procedures outlined belowshould be considered when developing astorm-water sampling program to complywith permit requirements or to monitor thequality of runoff and determine the effective-ness of BMPs.

Sampling a representative storm. Usingclimatic data, you can determine the averagerainfall depth and duration of rainfall eventsat the waste management unit site. Youshould sample during a representative stormevent. The representative storm should bepreceded by at least 72 hours of dry weatherand, when possible, should be between 50and 150 percent of the average depth andduration. The time to collect individual grabsamples is during the first flush (i.e., the first30 minutes of the event), and compositesamples should then be collected over thefirst 3 hours, or the entire event if less than 3hours. These guidelines help ensure that con-

stituents in the sampled runoff will not be soconcentrated or so dilute as to be unrepre-sentative of the overall runoff.

Determining the sample type. A grabsample is a discrete, individual sample takenwithin a short period of time, usually lessthan 15 minutes. Analysis of a grab samplecharacterizes the quality of a storm water-dis-charge at the time the sample was taken.These types of samples can be used to char-acterize the maximum concentration of aconstituent in the discharge.

A composite sample is a mixed or com-bined sample that is formed by combining aseries of individual and discrete samples ofspecific volumes at specified intervals. Theseintervals can be either time-weighted or flow-weighted. Time-weighted composite samplesare collected and combined in proportion totime, while flow-weighted composite samplesare combined in proportion to flow.Composite samples characterize the qualityof a storm-water discharge over a specificperiod of time, such as the duration of astorm event.

Determining the sample techniques.Grab and composite samples can be collectedby either manual or automatic sampling tech-niques. Manual samples are simply collectedby hand, while automatic samples are collect-ed by powered devices according to prepro-grammed criteria. Both techniques haveadvantages and disadvantages that need to beweighed when choosing a sampling tech-nique for a specific site. The advantages ofmanual sampling include its appropriatenessfor all constituents and its lower cost com-pared to automatic sampling. Manual sam-pling, however, can be labor intensive, canexpose personnel to potentially hazardousconditions, and is subject to human error.

The advantages of automatic sampling arethe convenience it offers, its minimum laborrequirements, its reduction of personnel

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exposure to hazardous conditions, and itslow risk of human error. Unfortunately, auto-matic sampling is not suitable for all con-stituent types. Volatile organic compounds(VOC), for example, can not be sampledautomatically due to the agitation duringsample collection. This agitation can causethe VOC constituents to completely volatilizefrom the sample. Other constituents such asfecal streptococcus, fecal coliform, and chlo-rine might also not be amenable to automaticsampling due to their short holding times.Since sample temperature and pH need to bemeasured immediately, the option for usingautomatic sampling for these parameters islimited as well. Automatic sampling can alsobe expensive, and does require a certainamount of training. Table 4 presents a com-parison of manual and automatic samplingtechniques.

Sampling at the outfall point. Storm-water samples should be taken at a storm-water point source. A “point source” isdefined as any discernible, confined, and dis-crete conveyance. The ideal sampling loca-tion is often the lowest point in a drainagearea where a conveyance discharges, such asthe discharge at the end of a pipe or ditch.The sample point should be easily accessibleon foot and in a location that will not causehazardous sampling conditions. You shouldnot sample during dangerous wind, light-ning, flooding, or other unsafe conditions. Ifthese conditions are unavoidable during anevent, then the sampling should be delayeduntil a less hazardous event occurs.Preferably, the sampling location will belocated onsite, but if it is not, obtain permis-sion from the owner of the property wherethe discharge is located. Inaccessible dis-charge points, numerous small point dis-charges, run-on from other properties, andinfinite other scenarios can cause logisticalproblems with sampling locations. If the dis-charge is inaccessible or not likely to be rep-

resentative of the runoff, samples might needto be taken at a point further upstream of thedischarge pipe or at several locations to bestcharacterize site runoff.

Coordinating with the laboratory. It isimportant to collect adequate sample vol-umes to complete all necessary analyses.When testing for certain constituents, sam-ples might need to be cooled or otherwisepreserved until analyzed to yield meaningfulresults. Section 3.5 of EPA’s NPDES StormWater Sampling Guidance Document (U.S. EPA,1992) contains information on proper samplehandling and preservation procedures.Submitting the proper information to the lab-oratory is important in ensuring proper sam-ple handling by the laboratory. Proper sampledocumentation guidelines are outlined inSection 3.7 of the NPDES Storm WaterSampling Guidance Document. Coordinationwith the laboratory that will be performingthe analysis will help ensure that these issuesare adequately addressed.

You are required to follow all samplingand monitoring requirements in an NPDESpermit. If there are no sampling require-ments, analyze runoff for basic constituents,such as oil and grease, pH, biochemical oxy-gen demand (BOD), chemical oxygendemand (COD), total suspended solids(TSS), phosphorus, and nitrogen, as well asany other constituents known or suspected tobe present in the waste, such as heavy metalsor other toxic constituents.

Additional sampling guidance can beobtained from EPA’s NPDES Storm WaterSampling Guidance Document (U.S. EPA,1992) and Interim Final RCRA FacilityInvestigation (RFI) Guidance: Volume III (U.S.EPA, 1989). In addition, state and local envi-ronmental agencies also have guidance onappropriate sampling methods.

There is a national system that providespermitting information for facilities holding

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Sample Method Advantages Disadvantages

Manual Grabs • Generally appropriate for all •Labor-intensiveconstituents •Environment possibly dangerous to field personnel

• Minimum equipment required • Might be difficult to get personnel and equipmentto the storm water outfall within the first 30 minutes of the event

• Possible human error

Manual Flow- • Generally appropriate for all •Labor-intensiveWeighted constituents • Environment possibly dangerous to field personnelComposites • Minimum equipment required •Human error can have significant impact on (multiple grabs) sample representativeness

•Requires that flow measurements be taken duringsampling

Automatic Grabs • Minimizes labor requirements •Samples not collected for oil and grease, might • Low risk of human error not be representative• Reduced personnel exposure to •Automatic samplers generally cannot properly

unsafe conditions collect samples for VOC analysis• Sampling can be triggered •Costly if numerous sampling sites require the

remotely or initiated according to purchase of equipmentpresent conditions • Can require equipment installation and

maintenance; can malfunction• Can require operator training• Might not be appropriate for pH and temperature• Might not be appropriate for parameters with

short holding times (e.g., fecal streptococcus,fecal coliform, chlorine)

• Cross-contamination of aliquot if tubing/bottles not washed

Automatic Flow- • Minimizes labor requirements •Generally not acceptable for VOC samplingWeighted • Low risk of human error •Costly if numerous sampling sites require the Composites • Reduced personnel exposure to purchase of equipment

unsafe conditions •Can require equipment installation and • Can eliminate the need for maintenance; can malfunction

manual compositing of aliquots •Can require operator training• Sampling can be triggered remotely •Can require that flow measures be taken during

or initiated according to onsite samplingconditions •Cross-contamination of aliquot if tubing/bottles

not washed

Table 4Comparison of Manual and Automatic Sampling Techniques

NPDES permits. This system is called thePermits Compliance System (PCS) and itallows users to retrieve information regardingfacilities holding NPDES permits, includingpermit limits and actual monitoring data. Youcan specify the desired information by usingany combination of facility name, geographiclocation, standard industrial classification(SIC) code, and chemical names. The PCSdatabase can be accessed at <www.epa.gov/enviro/html/water.html#PCS>.

B. Monitoring Dischargesto POTWs

As discussed in the Chapter 6–ProtectingSurface Water, industrial facilities dischargingto a POTW might have to meet “pretreatmentstandards.” If so,, they will be subject to cer-tain requirements under a local pretreatmentprogram. The National Pretreatment Programrequires certain POTWs in defined circum-stances to develop a local pretreatment pro-gram (see 40 CFR Section 403.8(a)). Theactual requirement for a POTW to developand implement a local program is a conditionof the POTW’s NPDES permit.

Sampling is the most common method forverifying compliance with pretreatment stan-dards. Monitoring locations are usually desig-nated by the local municipality administeringthe pretreatment program and will be suchthat compliance with permitted dischargelimits can be determined. Monitoring loca-tions should be appropriate for waste streamconditions, be representative of the discharge,have no bypass capabilities, and allow forunrestricted access at all times (see 40 CFRSection 403.12).

EPA’s General Pretreatment Regulationsrequire POTWs to monitor each significantindustrial user (SIU) at least annually (see 40CFR Section 403.8 (f)(2)(v)) and each SIU toself-monitor semi-annually, although permits

issued by the local control authority mightrequire more frequent monitoring (see 40CFR Section 403.12 (g) and (h)). The localmunicipality will develop and implementstandard operating procedures and policiesthat specify the sample collection and han-dling protocols in accordance with 40 CFRPart 136.

Sampling for constituents such as pH,cyanide, oil and grease, flashpoint, and VOCswill require manual collection of grab sam-ples (see 40 CFR Section 403.12 (b)(5)).Similar to composite samples, grab samplesmust be representative (see 40 CFR Section403.12 (g)(4)) of the discharge and must becollected from actively flowing waste streams.Fluctuations in flow or the nature of the dis-charge might require collection and hand-compositing of more than one grab sample toaccurately access compliance. Flow-weightedcomposite samples are preferred over time-weighted composite samples, particularlywhere the monitored discharge is intermittentor variable. The local authorities can waiveflow-weighted composite sampling if anindustrial user demonstrates that flow-weighted sampling is not feasible. In thesecases, time-weighted composite samples canbe collected (see 40 CFR Section 403.12(b)(5)(iii)). Refer to EPA’s Industrial UserInspection and Sampling Manual for POTWs(U.S. EPA, 1994a) for additional informationon sample collection and analysis proceduresfor the pretreatment program.

If you are subject to pretreatment require-ments and must conduct sampling to demon-strate compliance, the requirementsestablished for your site by the local controlauthority apply. These include following theproper sample collection and handling proto-cols and being able to prove that you did so(i.e., by keeping sampling records; notinglocation, date, and time of sample collection;maintaining chain of custody forms showingthe link between field personnel and the lab-


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oratory) (see 40 CFR Section 403.12(o)).Consult EPA’s Introduction to the NationalPretreatment Program document (U.S. EPA,1999) for further information on monitoringrequirements under the NationalPretreatment Program.

C. Monitoring SurfaceWater Conditions

In order to determine if runoff from yourwaste management unit is impacting adjacentsurface waters you might want to considerestablishing a surface-water quality monitor-ing program. Chemical, physical, and biolog-ical data can provide information about theeffectiveness of BMPs. The data collected willhelp you to characterize any overall waterquality at the selected monitoring sites, iden-tify problem areas, and document anychanges in water quality.

In designing your program, one of themost important things to consider is whattypes of parameters to monitor (chemical,physical, and/or biological) that will enableyou to determine how your waste manage-ment unit might be impacting the aquaticecosystem. Determining where you shouldset-up a monitoring station is also veryimportant and will depend on relevanthydrologic, geologic, and meteorologic fac-tors. For assistance and more information onestablishing water quality sampling stationsand a sampling program you should consultwith state and local water quality planningagencies. Additional guidance on establishingsampling and monitoring programs can beobtained from EPA’s Volunteer StreamMonitoring Document (U.S. EPA, 1997) andVolunteer Lake Monitoring Document (U.S.EPA, 1991). Monitoring can be conducted atregular sites on a continuous basis (“fixedstation” monitoring); at selected sites on anas needed basis or to answer specific ques-tions (“intensive surveys”); on a temporary or

seasonal basis (e.g., during periods of intenserainfall); or on an emergency basis (i.e., anaccidental spill or discharge).

Why is the monitoring taking

place?

You should first determine the purpose ofestablishing a surface-water monitoring pro-gram. Reasons for monitoring surface watercan include developing baseline characteriza-tion data prior to a waste management unitbeing constructed, documenting water quali-ty changes over time, screening for potentialwater quality problems, determining theeffectiveness of BMPs, or determining theimpact of the waste management unit on sur-face waters.

How will the data be used?

The data collected will help you to identifyconstituents of concern, the impacts of pollu-tion and pollution control activities (i.e.,BMPs), and trends in water quality. Note thatthe data you collect might also be useful toregional or local water quality planningoffices that might already be collecting simi-lar data in other parts of the watershed.

What parameters or conditions

will be monitored?

The basic parameters that are indicators ofgeneral water quality health, include dissolvedoxygen (DO), pH, total suspended solids(TSS), nitrogen, hardness, temperature, andphosphorous. In addition, you might chooseto monitor parameters that would indicatewhether the designated use (e.g., fisheries,recreation) of the water body is being met (asdiscussed in Chapter 6–Protecting SurfaceWater). Further, based on the types of con-stituents associated with the waste manage-ment unit, you should also sample forcontaminants that would indicate whetheryour surface-water protection measures are

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functioning properly (e.g., heavy metals,organics, or other materials associated with theunit). In many cases, a few surrogate con-stituents can be selected instead of analyzing acomplete spectrum of constituents. For exam-ple, lead, zinc, or cadmium are often selectedto indicate pollution by toxic metals. Insteadof analyzing for every possible pathogenicmicroorganism, total and fecal coliform bacte-ria analyses are commonly used to indicatebacterial and viral contamination. Chemicaloxygen demand (COD) and total organic car-bon (TOC) are used in high-frequency grabsampling programs as indicators of pollutionby organics.

Where should the monitoring

sites/stations be located?

In order to determine if the waste manage-ment unit is having an impact on surfacewater it is important to determine the qualityof the water upstream from the unit as well asdownstream. You should also consider thenumber of sites to establish how accessible,safe, and convenient potential sites are. Inaddition, it is important to determine if poten-tial sites are near tributary inflows, dams,bridges, or other structures that might affectthe sampling results. You should also deter-mine if you will establish permanent samplingstations (i.e., structures or buildings) or if thestations will simply be designated points with-in the watershed.

What sampling methods should

be used?

You must decide how the samples will becollected, what sampling equipment will beused (e.g., automatic samplers or by hand),what equipment preparation methods arenecessary (e.g., container sterilization, metercalibration), and what protocols will be fol-lowed. Refer to Part II, Section A of thischapter for a discussion of determining sam-

pling methods. EPA’s SW-846 also providesguidance on selecting the appropriate sam-pling methods.

When will the monitoring occur?

You need to establish how frequently mon-itoring will take place, what time of year isbest for sampling, and what time of day isbest for sampling. Monitoring at the sametime of day and at regular intervals helpsensure comparability of data over time. Ingeneral, monthly chemical sampling andtwice yearly biological sampling are consid-ered adequate to identify water qualitychanges over time. If you are conducting bio-logical sampling, it should be conducted atthe same time each year because of naturalseasonal variations in the aquatic ecosystem.Note that the frequency of sampling shouldbe increased during the rainy season as this iswhen contamination from waste managementunits is expected to increase due to storm-water runoff.

How can the quality of the data

collected be ensured?

You should develop a quality assuranceplan to ensure that quality assurance andquality control procedures are implementedat all times. In addition, the personnel con-ducting the sampling should be properlytrained and consider how to manage the dataafter the data have been collected.

Hydrologic and water quality informationis also collected and published regularly byEPA and the U.S. Geological Survey (USGS).Both agencies have computerized systems forstoring and retrieving information on waterquality that are available on the Internet.Water quantity and flow data in streams isalso available from USGS which has offices inevery state. USGS also operates two nationalstream water quality networks, theHydrologic Benchmark Network (HBN) and


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the National Stream Quality AccountingNetwork (NASQAN). These networks wereestablished to provide national and regionaldescriptions of stream water quality condi-tions and trends, based on uniform monitor-ing of selected watersheds throughout theUnited States, and to improve our under-standing of the effects of the natural environ-ment and human activities on water quality.Stream water quality measurements are avail-able for the approximate periods 1973 to1995 for NASQAN and 1962 to 1995 forHBN. For more information on how toobtain this water quality information, visitthe USGS Web site at <water.usgs.gov/pubs/FS/fs-014-00/index.html>.

III. Soil MonitoringThis section focuses primarily on estab-

lishing a soil monitoring program for landapplication purposes. Much of the followingdiscussion concerning sampling methods,protocols, and quality assurance and qualitycontrol, however, also is applicable to soilmonitoring for corrective action site assess-ments. Part I of Chapter 10–TakingCorrective Action outlines which parametersto consider when performing soil investiga-tions for corrective action purposes. Formore information on corrective action unitassessments, refer to the North CarolinaCooperative Extension Service’s Soil facts:Careful Soil Sampling - The Key to Reliable SoilTest Information (AG-439-30), the Universityof Nebraska Cooperative Extension Instituteof Agriculture and Natural Resources’Guidelines for Soil Sampling (G91-1000-A),and EPA’s RCRA Facility InvestigationGuidance: Volume II: Soil, Ground Water andSubsurface Gas Releases (U.S. EPA, 1989). Asdiscussed in Part I of this chapter, soil moni-toring can be used to detect the presence ofwaste constituents in the soil and track their

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EPA’s Water Quality DataManagement Systems

EPA maintains two data management sys-tems containing water quality information:the Legacy Data Center (LDC) and STORET.The LDC contains historical water qualitydata dating back to the early part of the 20thcentury and collected up to the end of 1998.STORET (short for STOrage and RETrieval)contains data collected beginning in 1999,along with older data that has been properlydocumented and migrated from the LDC.

Both systems contain biological, chemi-cal, and physical data on surface andground water collected by federal, state andlocal agencies, Indian Tribes, volunteergroups, academics, and others. All 50 states,territories, and jurisdictions of the U.S. arerepresented.

Each sampling result in these databases isaccompanied by information on where thesample was taken (e.g., latitude, longitude,state, county, Hydrologic Unit Code), whenthe sample was gathered, the medium sam-pled (e.g., water, sediment, fish tissue), andthe name of the organization that sponsoredthe monitoring. In addition, STORET con-tains information on why the data weregathered; the sampling and analytical meth-ods used; and the quality control checksused when sampling, handling, and analyz-ing the data.

The LDC and STORET databases areWeb-enabled. With a standard Web brows-er, you can browse both systems interactive-ly or create files to be downloaded to yourcomputer. For more information on theLDC and STORET data management sys-tems and how the water quality data can beobtained visit EPA’s STORET Web site at<www.epa.gov/storet>.

migration before they reach ground water.Characterizing the soil properties at a landapplication site can also help you determinethe application rates that will maximize wasteassimilation.

To obtain site-specific data on actual soilconditions, the soil should be sampled andcharacterized. The number and location ofsamples necessary for adequate soil character-ization is primarily a function of the variabili-ty of the soils at a site. If the soil types occurin simple patterns, a composite sample ofeach major soil type can provide an accuratepicture of the soil characteristics. The depthto which the soil profile is sampled, and theextent to which each horizon is verticallysubdivided, will depend on the parameters tobe analyzed, the vertical variations in soilcharacter, and the objectives of the soil sam-pling program. You should rely on a qualifiedsoil scientist to perform this characterization.Poorly conducted soil sampling can result in

an inaccurate soil characterization whichcould lead to improper application of wasteand failure of the unit to properly assimilatethe applied waste.

A. Determining the Qualityof Soil

Soil quality is an assessment of how wellsoil performs all of its functions, not just howwell it assimilates waste. Measuring crop yield,nutrient levels, water quality, or any other sin-gle outcome alone will not give you a com-plete assessment of a soil’s quality. Theminerals and microbes in soil are responsiblefor filtering, buffering, degrading, immobiliz-ing, and detoxifying organic and inorganicmaterials, including those applied to the landand deposited by the atmosphere. Determiningthe quality of a soil is an assessment of how itperforms all of these functions in addition towaste assimilation. For assessing soil quality inrelation to land application units, it will be


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Examples of Indicators of Soil Quality

Indicator Relationship to Soil Health

Soil organic matter (SOM). Soil fertility, structure, stability, nutrient retention,soil erosion.

PHYSICAL: soil structure, Retention and transport of waterdepth of soil, infiltration and bulk and nutrients, habitat for density, water holding capacity. microbes, estimate of crop productivity potential,

compaction, water movement, porosity, workability.

CHEMICAL: pH, electrical Biological and chemical activityconductivity, extractable nitrogen- thresholds, plant and microbialphosphorous-potassium. activity thresholds, plant available nutrients and

potential for nitrogen and phosphorous loss.

BIOLOGICAL: microbial biomass, Microbial catalytic potential and carbon and nitrogen, potentially repository for carbon andmineralizable nitrogen, soil nitrogen, soil productivity andsupplying potential, microbial respiration.activity measure.

important for the soil to be able to filter thewaste constituents and cycle nutrients such ascarbon, nitrogen, and phosphorus.

Measuring soil quality requires the use ofphysical, chemical, and biological indicators,which can be assessed by qualitative or quan-titative techniques. After measurements arecollected, they can be evaluated by lookingfor patterns and comparing results to mea-surements taken at a different time or field.For more information, consult the Guidelinesfor Soil Quality Assessment prepared by theSoil Quality Institute of the NaturalResources Conservation Service (formerly theU.S. Soil Conservation Service).

B. Sampling Location andFrequency

Prior to sampling, divide the land applica-tion unit into uniform areas, then collect rep-resentative samples from each area. Thesedivisions should be based upon soil type,slope, degree of erosion, cropping history,known crop growth differences, and anyother factors that might influence nutrientlevels in the soil. One recommendedapproach is to divide the unit into areas nolarger than 20 acres and to collect at leastone sample from each of these areas.

Each sample for a designated area consistsof a predetermined number of soil cores. Asoil core is an individual boring at one spotin the field. The recommended number ofcores per sample are 15-20 cores for a sur-face soil sample and 6-8 cores for a subsur-face sample. If using a soil probe, a singlecore can be separated into its horizontal lay-ers to provide samples for each layer beinganalyzed. For example, a single core could bedivided into four predefined layers such assurface soil, subsurface soil, and two deepsubsurface soil. For a designated area, all theindividual cores are combined according to

soil level and mixed to provide a compositesample for the area. From the mixed cores acomposite subsample should be taken andanalyzed. Each grab sample can be analyzedindividually, rather than combined, as part ofa composite sample (discussed below), butcomposite samples generally provide reliabledata for soil characterization.

Soil core grab samples can be collected atrandom or in a grid pattern. Random collec-tion generally requires the least amount oftime, but cores must be collected from theentire area to ensure reliable site characteriza-tion. When performed properly, randomsampling will provide an accurate assessmentof average soil nutrient and constituent lev-els. While the preparation required for col-lecting core samples in a grid pattern can bemore costly and time consuming, it doesensure that the entire area is sampled. Anadvantage of grid sampling is the ability togenerate detailed nutrient level maps for aland application unit. This requires analysisof each individual grab sample from an area,rather than compositing samples. Analyzingeach individual grab sample is time consum-ing and expensive, but software and comput-erized applicators are becoming available thatcan use these data to tailor nutrient applica-tion to soil needs.

You should determine baseline conditionsby sampling the soil before waste applicationbegins. Subsequent sampling will depend onland use and any state or local soil monitor-ing requirements. After waste is applied tothe land application unit, you should collectand analyze samples at regular intervals, orafter a certain number of applications. Youshould sample annually, at a minimum, ormore frequently, if appropriate.

The frequency of sampling, the micronu-trients, the macronutrients, and the con-stituents to be analyzed will depend onsite-specific soil, water, plant, and waste

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characteristics. Local agricultural extensionservices, which have experience with design-ing soil-sampling programs, can assist in thisarea. Soil monitoring, especially when cou-pled with ground-water monitoring, candetect contamination problems. Early detec-tion allows changes to be made to the landapplication process to remedy the problemsand to conduct corrective action if necessary.Finally, soil testing after the active life of theunit has ended is recommended to determineif any residues remain in the soil.

C. Sampling EquipmentThere are a number of soil sampling

devices available. A soil probe or tube is themost desirable, as it provides a continuouscore with minimal disturbance of the soil.Sample cores from a soil probe can be divid-ed by depth and provide surface, subsurface,and deep subsurface samples from a singleboring. When the soil is too wet, too dry, orfrozen, however, soil probes are not veryeffective. The presence of gravel in the soilwill also prevent the use of a soil probe.

When sampling excessively wet, dry, orfrozen soils, or soils with gravel, a soil augercan be used in place of a soil probe. Becauseof their tendency to mix soils from differentdepths during sample collection, a soil augershould only be used when the use of a soilprobe is not possible. A spade can also beused for surface samples, but it is not effec-tive for subsurface sampling. Post-hole dig-gers can be used for collecting deepersubsurface samples, but they present thesame mixing problem as soil augers. EPA’sDescription and Sampling of Contaminated Soils:A Field Pocket Guide (U.S. EPA, 1991) con-tains a description of various hand-held andpower-driven tube samplers. The guide alsooutlines the recommended applications andlimitations for each sampling device.

D. Sample CollectionInitial soil characterization samples are

typically taken from each distinct soil horizondown to a depth of 4-5 feet (120-150 cm).For example, a single core sample might pro-vide the following four horizon samples: sur-face (0-6 inches), subsurface (6-18 inches),and two deep subsurface (18-30 inches and30-42 inches). For subsequent evaluations, itis important to sample more than just thesurface layer to determine if the land applica-tion rate is appropriate and that the quality ofsoil is not being detrimentally affected.Sampling subsurface layers will indicatewhether waste constituents are beingremoved and assimilated as expected and arenot leaching into subsurface layers or thegroundwater. As a minimum practice, sampleat least the upper soil layer (0-6 inches) andat least one deeper soil layer (e.g., 18-30inches). You should consult the local agricul-tural extension service, the county agricultur-al agent, or other soil professionals forrecommended soil sampling depths for thespecific area in which your land applicationunit is located.

Once the samples have been obtained,they must be prepared for chemical analysis.This typically is done by having the sampleair dried, ground, and mixed, and thenpassed through a 2 millimeter sieve as soonas possible after collection. If the samples areto be analyzed for nitrate, ammonia, orpathogens, then they should be refrigeratedunder moist field conditions and analyzed assoon as possible. For more information onhandling and preparing soil samples, refer tothe “General Protocol for Soil SampleHandling and Preparation” section in EPA’sDescription and Sampling of Contaminated Soils:A Field Pocket Guide (U.S. EPA,1991). ASTMmethod D-4220 Practices for Preserving andTransporting Soil Samples also addresses prop-er soil sample handling protocols.


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The exact procedure for drying is not criti-cal as long as contamination is minimizedand excessive temperatures are avoided. Therecommended drying procedure for routinesoil analysis is to dry the samples overnight,using forced air at ambient temperatures.Supplemental heating can be used, but it isrecommended that soil samples to be usedfor routine analyses not be dried at greaterthan 36°C. Microwave drying can alter theanalytical results and should be avoided.

Because soil is defined as having a particlesize of less than 2 millimeters, this sieve size(# 10 mesh) is recommended for routine soiltesting. Commercial soil grinders and crush-ers, such as mortar and pestles, hammer-mills, or roller-crushers, are typically longand motorized. The amount of coarse frag-ments common in some samples limits theuse of some of these. In general, it is desir-able to get most of the sample to less than 2mm with the least amount of grinding. If thesample is to be analyzed for micronutrients,all contact with metal surfaces should beavoided during crushing and sieving unless ithas been clearly demonstrated that the metalis not a source of contamination. Cross-cont-amination between samples can be avoidedby minimizing soil-particle carry over on thecrushing and sieving apparatus. Formacronutrient analysis, removal of particlesby brushing or jarring should be adequate. Ifmicronutrient or trace element analysis is tobe performed, a more thorough cleaning ofthe apparatus by brushing or wiping betweensamples might be required.

The bulk soil sample should be thorough-ly homogenized by mixing with a spatula,stirring rod, or other implement. As much ofthe sample as possible should be loosenedand mixed together. No segregation of thesample by aggregate size should be apparentafter mixing. You should dip into the centerof the mixed sample to obtain a subsamplefor analysis.

Prior to sampling, all containers andequipment that are to be used for soil collec-tion (i.e., those that will come in contactwith the soil being sampled) should berinsed in warm tap water to remove anyresidual soil particles from previous samplingruns. They should then be rinsed with analuminum chloride solution. Avoid usinganhydrous aluminum chloride due to its vio-lent reaction with water. A four percenthydrogen chloride solution can also be usedif the soil is not to be analyzed for chlorine.The containers and equipment should berinsed twice in distilled or deionized waterand allowed to dry prior to use.

You should obtain professional assistancefrom qualified soil scientists and laboratoriesto properly interpret the soil-sample results.For more information about how to obtainrepresentative soil samples and submit themfor analysis, you can consult various federalmanuals, such as EPA’s Laboratory Methodsfor Soil and Foliar Analysis in Long-TermEnvironmental Monitoring Programs (U.S. EPA,1995b), or state guides, such as Nebraska’sGuidelines for Soil Sampling (G91-1000-A).The following ASTM methods might alsoprove useful when conducting soil sampling:D-1452 Practice for Soil Investigation andSampling by Auger Borings; D-1586 TestMethod for Penetration Test and Split-BarrelSampling of Soils; D-1587 Practice for Thin-Walled Tube Sampling of Soils; and D-3550Practice for Ring-Lined Barrel Sampling of Soils.

IV. Air MonitoringThe development of appropriate air-moni-

toring data can be technically complex andresource intensive. The Industrial Waste Air(IWAIR) Model on the CD ROM version ofthis Guide provides a simple tool that relieson waste characterization information, ratherthan actual air monitoring data, to evaluate

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risks from VOC emissions at a unit. The air-modeling tool uses an emissions model toestimate emissions from a waste managementunit based on the waste characterization. Youshould review Chapter 5–Protecting AirQuality, and the supporting background doc-ument developed for the IWAIR model tounderstand the limitations of the model anddetermine whether it is applicable to a specif-ic unit. If the model is not appropriate for aspecific site or if it indicates that there is aproblem with VOC emissions, use an alterna-tive (emissions) model that is more appropri-ate for the site or consider air monitoring togather more site-specific data.

A. Types of Air EmissionsMonitoring

There are generally four different types ofair emissions monitoring: source, ambient,fugitive, and indoor. Source, ambient, andfugitive monitoring can provide data for usein emission and dispersion modeling. Inaddition, the monitoring of meteorologicalconditions at sites is generally conductedwhenever source emissions or ambient moni-toring is performed, as discussed below. Asthe vast majority of industrial waste manage-ment units are located outdoors, indoor airquality and monitoring issues typically willnot apply. Consequently, this guide does notaddress this issue. For more information onindoor air quality and monitoring visit theOccupational Safety and HealthAdministration’s (OSHA) Web site at<www.osha-slc.gov/SLTC/indoorairquality/index.html>.

1. Emissions MonitoringStationary-source emissions monitoring

involves the direct sampling of an air streamin a duct, stack, or pipe that is the end sourceof an emission release point. A stationary

source is an immobile unit from which airpollutants are released. Examples includeincinerators, boilers, industrial furnaces,landfills, waste piles, surface impoundments,and other waste management units. The pur-pose of source sampling is to obtain as accu-rate a sample as possible of the materialentering the atmosphere. The major reasonsfor which source testing is required are todemonstrate compliance with regulations orpermit conditions, to collect engineering data(e.g., to evaluate the performance of air pol-lution control equipment), to support perfor-mance guarantees (e.g., checking to confirmthat the air pollution control equipment ismeeting the guaranteed degree of perfor-mance), and to provide data for air modeling.

2. Ambient MonitoringThe second type of air monitoring involves

ambient air monitoring at selected locationsaround the waste management unit or site.The data are used to monitor dispersion ofairborne contaminants to the surroundingareas. Ambient testing usually involves“fenceline” testing. Typically, the air is moni-tored at the four fenceline compass points. Atleast one additional measuring station isplaced either in the predominant upwind (ordownwind) location or in a direct linebetween your site and a neighboring facilityor property. The resulting data should yieldinformation concerning the concentration ofambient emissions leaving your property(minus the emissions from adjacent facilities).

In many areas of the country, several facili-ties share property boundaries delineated by afenceline. Since each facility is regulatedaccording to total emissions, it is critical that aneighboring facility’s “drifting” emissions bequalified and quantified. Depending on theneighboring facility’s production rate, theatmospheric conditions, and the seasonal cli-mate, the neighboring facility’s emissions could


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impact the operation of your facility. Forexample, many facilities are required to con-tinuously monitor downwind fenceline emis-sion of hydrocarbons. If a neighboring facility’semissions of hydrocarbons or adjacent freewayhydrocarbon emissions drift across your fence-line and combine with your own hydrocarbonemissions, your total facility hydrocarbonemission limit could be violated.

3. Fugitive MonitoringFugitive testing is a hybrid of ambient and

source testing and generally involves themonitoring of either particulate or gaseousemissions from sources open to the atmos-phere. It can involve testing sources such asvalves, flanges, pumps, and similar equipmentand hardware for leaks, and it can includequantifying emissions from open drums, openvats, landfills, waste piles, and surfaceimpoundments such as lagoons, pits, and set-tling ponds. It is typically conducted usingone or more of the following techniques: useof a handheld organic analyzer; “bagging” sus-pect sources for subsequent analysis; captur-ing and scrubbing fugitive emissions using afloating flux chamber/summa canister; ormeasuring particulate matter greater than orless than 10 microns in diameter (PM10) fol-lowing promulgated EPA test methods.

Selection of the test method depends onfactors such as the type of emissions, sourcetype, temperature, pressure, constituent con-centration, etc. (test methods are discussedlater in this chapter). For example, a plantoperator who suspects that a valve is leakingmight use a handheld organic analyzer to ver-ify the presence of a leak. If the analyzer isnot able to quantify the concentration of theleaking gas, then the bagging technique canbe employed. To determine the amount andtype of organic emissions escaping from a set-tling pond or wastewater treatment tank, afloating flux chamber/summa canister might

be preferred. This is a box that isolates a por-tion of the pond to determine volumetricflow. The box acts as a floating stack in whichemissions are captured into a canister foranalysis. For material transfer operations orvehicular traffic from unpaved roads, it isobviously not practical to use a handheld ana-lyzer or to “bag” the source (especially some-thing as large as a waste pile). In such cases ofparticulate matter fugitive emissions, a high-volume ambient PM10 sampling system isused, or the emissions are ducted through atemporary stack for direct measurement usinga sampling train (see Figure 6).

4. Meteorological MonitoringAnother form of air monitoring measures

meteorological conditions at a site. Site-spe-cific meteorological information can be col-lected for use in air emission and dispersionmodeling. This type of monitoring involvesmeasurement of wind speed, wind direction,temperature, etc., and can be performedwhen other offsite meteorological informa-tion might not adequately characterize theweather conditions at the site. Local windsystems are usually quite significant in termsof the transport and dispersion of air con-stituents. Therefore, local meteorologicalmonitoring will most likely be important formountainous or hilly terrain (where solarheating and radiational cooling influencehow wind moves) or for a site near a largebody of water (where the differential heatingof land and water can result in thermals andsubsidence over water). Also, the initialdirection of transport of constituents fromtheir source is determined by the winddirection at the source.

To make meteorological measurements,three components are typically needed: adetector or sensor, an encoder or digitizer,and a data logger. Most detectors are analog,providing a continuous output as a function

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of varying meteorological conditions. Theoutput signal must then be sampled to pro-duce a discrete digital record, using some sortof encoder or analog-to-digital converter. Theresulting discrete series of data must berecorded, often on magnetic tape, magneticdisks, or optical disks. “Instrument system”or “instrument package” is the name given tothe set of all three components listed above.

Additional components might also be nec-essary including: an instrument platform, ameans of calibration, and display devices.Platforms, such as a tower, can often holdmany instrument systems. Calibration againstknown standards should be performed peri-odically during the measuring program, orshould be accomplished continuously as afunction of the sensor or instrument package.All data must be calibrated. Finally, the mea-sured values should be displayed on printers,plotters, or video displays in order to confirmthe proper operation of the instrument.

A large variety of sensors have been devel-oped to measure various meteorologic para-meters. Direct sensors are ones that areplaced on an instrument platform to make insitu measurements of the air at the location ofthe sensor. Remote sensors measure wavesthat are generated by, or modified by, theatmosphere at locations distant from the sen-sor. These waves propagate from the genera-tion or modification point back to the sensor.Disadvantages of direct sensors include modi-fication of the flow by the sensor or its plat-form and the requirement to physicallyposition the sensor where the measurement isto be made. Disadvantages of remote sensorsinclude their size, cost, and complexity.Advantages of direct sensors include sensitivi-ty, accuracy, and simplicity. Advantages ofremote sensors include the fact that they canquickly scan a large area while remaining sta-tionary on the ground.


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Sensors Used To MeasureMeteorologic Parameters

The following types of sensors can be used tomonitor meteorological conditions at a site (notethat this list is not meant to be exhaustive):

Temperature—thermometers.Direct sensors: Remote sensors:wax thermostat microwave soundersthermistor sodarbimetallic strip thermistorthermocoupleliquid (mercury or alcohol) in glassradiometers

Humidity—hygrometers.Direct sensors: Remote sensors:psychrometers lidarhair hygrometer radarchilled mirror (dew pointer)hygristor

Wind—velocity (anemometers) anddirection (vanes).Direct senors: Remote sensors:cup Doppler radarpropellarwind vanebivane

Pressure—barometers and microbarographs.Direct sensors:aneroid elementscapacitive elementsmercury in glass

Remote sensors:None that use wave propagation directly, butsome that measure temperature and velocityfluctuations as mentioned above, and inferpressure perturbations as residual from govern-ing equations.

Radiation—radiometers.Radiometers can be designed to measure radia-tion in specific frequency bands coming fromspecific directions: radiometer, net radiometer,pyranometer, and net pyranometer.

B. Air Monitoring andSampling Equipment

1. Ambient Air MonitoringFor ambient air monitoring, the principal

requirement of a sampling system is to obtaina sample that is representative of the atmos-phere at a particular place and time. Themajor components of most sampling systemsare an inlet manifold, an air mover, a collec-tion medium, and a flow measurementdevice. The inlet manifold transports materialfrom the ambient atmosphere to the collec-tion medium, or analytical device, preferablyin an unaltered condition. The inlet openingcan be designed for a specific purpose. Allinlets for ambient sampling must be rain-proof. Inlet manifolds are made out of glass,Teflon, stainless steel, or other inert materialsand permit the remaining components of thesystem to be located at a distance from thesample manifold inlet. The air mover (i.e.,pump) provides the force to create a vacuumor lower pressure at the end of the samplingsystem. The collection medium for a sam-pling system can be a liquid or solid sorbent

for dissolving gases, a filter surface for col-lecting particles, or a chamber to contain analiquot of air for analysis. The flow devicemeasures the volume of air associated withthe sampling system. Examples of flowdevices include mass flow meters androtameters.

Gaseous Constituents

Sampling systems for gaseous constituentscan take several forms and might not neces-sarily have all four components as shown inFigure 5. The sampling manifold’s only func-tion is to transport the gas from the manifoldinlet to the collection medium. The manifoldmust be made of nonreactive material and nocondensation should be allowed to occur inthe sampling manifold. The volume of themanifold and the sampling flow rate deter-mine the time required for the gas to movefrom the inlet to the collection medium. Thisresidence time can be minimized to decreasethe loss of reactive species in the manifold bykeeping the manifold as short as possible.

The collection medium for gases can beliquid or solid sorbents, and evacuated flask,

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Figure 5. Schematic Diagram of Various Types of Sampling Systems

Source: Fundamentals of Air Pollution.

or a cryogenic trap. Each design is an attemptto optimize gas flow rate and collection effi-ciency. Higher flow rates permit shorter sam-pling times. Liquid collection systems takethe form of bubblers which are designed tomaximize the gas-liquid interface. However,excessive flow rates can result in lower collec-tion efficiency.

Diagram A is typical of many extractivesampling techniques (e.g., SO2 in liquid sor-bents and polynuclear aromatic hydrocarbonson solid sorbents). Diagram B is used for“open-face” filter collection, in which the fil-ter is directly exposed to the atmospherebeing sampled. Diagram C is an evacuatedcontainer used to collect an aliquot of air orgas to be transported to the laboratory forchemical analysis, (e.g., polished stainlesssteel canisters are used to collect ambienthydrocarbons for air toxic analysis). DiagramD is the basis for many of the automated con-tinuous analyzers, which combine the sam-pling and analytical processes in one piece ofequipment (e.g., continuous ambient airmonitors for SO2, O3, and NOx).

Particulate Constituents

Sampling for particulate constituents in theatmosphere involves a different set of parame-ters from those used for gases. Particles areinherently larger than the molecules of N2 andO2 in the surrounding air and behave differ-ently with increasing diameter. When sam-pling for particulate matter in the atmosphere,three pieces of information are of particularinterest: the concentration, the size, and thechemical composition of the particles. Particlesize is important in determining adverseeffects and atmospheric removal processes.

The primary approach is to separate theparticles from a known volume of air andsubject them to weight determination andchemical analysis. The principle methods for

extracting particles from an airstream are fil-tration and impaction.7 All sampling tech-niques must be concerned with the behaviorof particles in a moving airstream. Care mustbe taken to move the particles through themanifold to the collection medium in anunaltered form. Potential problems arise ifmanifold systems are too long or too twisted.Gravitational settling in the manifold willremove a fraction of the very large particles.Larger particles are also subject to loss byimpaction on walls at bends in a manifold.Particles can also be subject to electrostaticforces which will cause them to migrate tothe walls of nonconducting manifolds. Otherpotential problems include condensation oragglomeration during transit time in the man-ifold. These constraints require particulatesampling manifolds to be as short as possibleand to have as few bends as possible.

2. Source Emissions MonitoringFor source emissions monitoring, the sam-

pling system is tailored to the unique proper-ties of the emissions from a particularprocess. It is necessary to take into accountthe specific process, the nature of the controldevices, the peculiarities of the source, andthe use of the data obtained. In source moni-toring, the sample is obtained from a stackthat is discharging to the atmosphere using a“sampling train”. A typical sample train isshown in Figure 6. The figure shows the min-imum number of components, but in somesystems the components can be combined.Extreme care must be exercised to assure thatno leaks occur in the train and that the com-ponents of the train are identical for both cal-ibration and sampling. Standard samplingtrains are specified for some tests.Continuous emission monitors (CEMs) arealso available to monitor opacity and certaingaseous emissions.


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7 Filtration consists of collecting particles on a filter surface by three processes: direct interception, iner-tial impaction, and diffusion. Filtration attempts to remove a very high percentage of the mass andnumber of particles by these processes. Any size classification is done by a preclassifier, such as animpactor, before the particle stream reaches the surface of the filter

C. Test Method SelectionCorrect method selection is both scientific

and subjective. Knowing when to utilize theappropriate method for a given circumstanceis very important, since incorrect or inaccu-rate measurement can lead to incorrectresults. The test methods to be used for airemission monitoring are typically specifiedby applicable regulations; and the type offacility will often determine the regulations orstandards which are applicable. In general,most EPA test methods applicable to a facilitywill be contained in the Code of FederalRegulations (40 CFR Parts 60, 61, 63, and51). Other test methods might be specifiedby the EPA Office of Solid Waste or theNational Institute for Occupational Safetyand Health (primarily for indoor air monitor-ing). Additionally, some states and local airpollution control agencies have their own testmethods that differ from EPA methods, theuse of which might be required in lieu ofEPA methods. The CFR specifies test meth-ods for testing for numerous compounds andvarious parameters necessary for determiningconstituent concentrations and emissionrates. New regulations, however, are beingdeveloped for many compounds that, as yet,

have no promulgated test methods. Air emis-sion testing specialists or consultants canoften determine appropriate test methods formost of these compounds. Usually, the test-ing involves adapting an existing method tothe constituent of interest. It is best to use anexisting method whenever possible. If usingan existing method is impractical, you candevelop a test method particular to that con-stituent to monitor for it. You should seekthe advice or assistance of a professional ifthis is the case and consult your state andlocal air quality offices.

D. Sampling Site SelectionSampling activities are typically undertaken

to determine the ambient air quality for com-pliance with air quality standards, to evaluatethe effectiveness of air pollution control tech-niques being implemented at the site, to eval-uate hazards associated with accidental spills,and to collect data for air emissions and dis-persion modeling. The purpose or use of theresults of the monitoring program determinesthe sampling site selection. The fundamentalreason for controlling air pollution sources isto limit the concentration of contaminants in

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Figure 6. Sampling Train

Source: Fundamentals of Air Pollution.

the atmosphere so that adverse effects do notoccur. Sampling sites should therefore beselected to measure constituent levels close toor representative of exposed populations ofpeople, plants, trees, materials, or structures.As a result, ambient air monitoring sites aretypically located near ground level, about 3

meters above ground (Boubel, p. 192.), in aplace where the results are not influenced by anearby source such as a roadway. Samplingsites might require electrical power and ade-quate protection (which can be as simple as afence). A shelter, such as a small building,might be necessary. Permanent sampling sites(when necessary) will require adequate heat-ing and air conditioning to provide a stableenvironment for the sampling and monitoringequipment.

V. Sampling andAnalyticalProtocols andQualityAssurance andQuality Control

The best designed monitoring programwill not provide useful data in the absence ofsound sampling and analytical protocols.Sampling and analytical protocols are gener-ally contaminant specific. A correctlydesigned and implemented sampling andanalysis protocol helps ensure that samplingresults accurately represent media quality andcan be compared over time. The accuraterepresentation is demonstrated through statis-tical analysis.

Whether or not an established qualityassurance and quality control (QA/QC) pro-gram is required on a federal, state, or locallevel, it is a good management practice todevelop and strictly implement such a plan.The sampling protocol should incorporatefederal, state, and local QA/QC requirements.Sampling QA/QC procedures detail steps forcollection and handling of samples. Samplecollection, preservation, shipment, storage,


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EPA Test Methods EPA test methods are available for a

variety of compounds and parameters,including but not limited to the follow-ing examples:

• Particulate Matter

• Volatile Organic Compounds (VOC)

• Sulfur Dioxide

• Nitrogen Oxide

• Visible Emissions

• Carbon Monoxide

• Hydrogen Sulfide

• Inorganic Lead

• Total Fluoride

• Landfill Gas (gas production flowrate)

• Nonmethane Organic Compounds(NMOC) (in landfill gases)

• Hydrogen Chloride

• Gaseous Organic Compounds

• Polychlorinated Dibenzo-p-dioxinsand Polychlorinated Dibenzofurans

• Stack Gas Velocity and VolumetricFlow Rate

• Gas Analysis for Carbon Dioxide,Excess Air, and Dry Molecular Weight

• Moisture Content in Stack Gases

and analysis should be performed in accor-dance with an approved QA/QC program toensure data of known quality are generated.

You should rely on qualified professionalswho are properly trained to conduct sam-pling. Poorly-conducted sampling can givefalse evidence of a contamination problem orcan miss early warnings of contaminantleaching. Erring in either direction is anavoidable and costly mistake.

At a minimum, you should include thefollowing in your sampling protocol:

• Data quality objectives including listsof important tracking parameters,such as the date and name of sam-ples.

• Sample collection procedures,including description of sample col-lection methods, and lists of neces-sary field analyses.

• Instructions for sample preservationand handling.

• Other QA/QC procedures such aschain-of-custody.

• The name of the person who con-ducted the sampling.

Quality control operations are defined byoperational procedures and might contain thefollowing components for an air monitoringprogram:

• Description of the methods used forsampling and analysis.

• Sampling manifold and instrumentconfiguration.

• Appropriate multipoint calibrationprocedures.

• Zero/span checks and record ofadjustments.

• Control specification checks andtheir frequency.

• Control limits for zero, span, andother control limits.

• The corrective actions to be takenwhen control limits are exceeded.

• Preventative maintenance.

• Recording and validation of data.

• Documentation of quality assuranceactivities.

States have developed guidance docu-ments addressing sampling plans, protocols,and reports. You should work with the stateto develop an effective sampling protocol.

• You should consult with soil special-ists at the state and local environ-mental/planning offices, your localcooperative extension service office,or the county conservation districtoffice before implementing a soilmonitoring program for your unit.(For more information, visit theUSDA Cooperative State Research,Education, and Extension ServiceWeb site at: <www.reeusda.gov/1700/statepartners/usa.htm>).These agencies likely will be able toprovide you with maps showing thelocation and extent of soils, dataabout the physical and chemicalproperties of soils, and informationderived from the soil data about

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potentialities and problems of use forthe soils in your area. You can alsoconsult the Natural ResourcesConservation Service (NRCS) Website at <www.wv.nrcs.usda.gov>.The NRCS manages the nationalcooperative soil survey programwhich is a partnership of federal landmanagement agencies, state agricul-tural experiment stations, and stateand local agencies that provide soilsurvey information necessary forunderstanding, managing, conserv-ing, and sustaining soil resources.The NRCS maintains various on-linedatabases that can help you to char-acterize local soil.

• You should consult with air modelingprofessionals, state and local air qual-ity offices, EPA Regional air programoffices, or EPA’s Office of Air QualityPlanning and Standards (OAQPS) inResearch Triangle Park, NorthCarolina, before implementing an airmonitoring program for your unit orchoosing alternative emission anddispersion models to evaluate risksassociated with air emissions. Forinformation concerning emission testmethods, you can contact theEmission Measurement Center (EMC)within the Office of Air QualityPlanning and Standards. The EMC isEPA’s point of contact for providingexpert technical assistance for EPA,state, and local officials and industrialrepresentatives involved in emissiontesting. The Center has producednumerous methods of measuring airconstituents emitted from a multitudeof industries. A 24-hour automatedtelephone information hotline knownas the “SOURCE” at 919 541-0200,provides callers with a variety oftechnical emission testing informa-

tion. The SOURCE also includes con-nections to technical materialthrough an automatic facsimile linkand with technical staff during work-ing hours. For more information con-cerning the EMC, visit EPA’s Web siteat: <www.epa.gov/ttn/emc>.

OAQPS also maintains the SupportCenter for Regulatory Air Models(SCRAM). The SCRAM Web site<www.epa.gov/scram001> is a sourceof information on various atmospher-ic dispersion (air quality) models thatsupport regulatory programs requiredby the Clean Air Act. The computercode, data, and technical documentsprovided by SCRAM deal with math-ematical modeling for the dispersionof air constituents. Documentationand guidance for these computerizedmodels are a major feature of theWeb site.

A. Data Quality ObjectivesIn any sampling and analysis plan, it is

important to understand the data needs for amonitoring program. Tailoring sampling proto-col and analytical work to data needs ensurescost-efficient sampling. A sampling and analy-sis plan should specify: 1) clear objective, suchas what data are needed and how the data areto be used, 2) target contaminants, and 3)level of accuracy requirements for data to beconclusive. Chapter 1 of EPA SW-846 TestMethods for Evaluating Solid Waste (U.S. EPA,1986) and ASTM Guide D5792 provide guid-ance on developing data quality objectives forwaste management activities.

B. Sample CollectionSample collection techniques should be

carefully designed to ensure sampling qualityand avoid cross-contamination or background


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contamination of samples. (As an example ofsome of the sample collection guidance avail-able, Section A.4 of the Annual Book of ASTMStandards lists guides for ground-water sam-pling.) You should consider the following fac-tors when preparing for sample collection.

• Sample collection. The equipmentused to collect samples should beappropriate for the monitoring para-meters. Sampling equipment shouldcause minimal agitation of the sam-ple and reduce or eliminate contactbetween the sample and environmen-tal contaminants during transfer toensure it is representative.

• Field analysis. Some constituents orparameters can be physically or chem-ically unstable and should be tested inthe field rather than waiting for ship-ment to a laboratory. Examples ofunstable parameters include pH,redox (oxidation-reduction) potential,dissolved oxygen, temperature, andspecific conductance.

C. Sample Preservationand Handling

Sample preservation and handling proto-cols are designed to minimize alterations ofthe chemistry of samples between the timethe sample is collected and when it is ana-lyzed. You should consider the following.

• Sample containers. To avoid alteringsample quality, transfer samples fromthe sampling equipment directly intoa contaminant free container. SW-846, identifies proper sample con-tainers for different constituents andmedia. Samples should not be com-bined in a common sample containerand then split later in the field.

• Sample preservation. The timebetween sampling and sample analy-sis can range from several hours toseveral weeks. Immediate samplepreservation and storage assists inmaintaining the natural chemistry ofthe samples. The latest edition ofSW-846 provides specific preserva-tion methods and holding times foreach constituent analyzed. SW- 846recommends preservation methods,such as pH adjustment, chemicaladdition, and refrigeration.

• Sample transport. To documentsample possession from the time ofcollection to the laboratory, include achain-of-custody record in every sam-ple shipment. A chain-of- custodyrecord generally includes the dateand time of collection, signatures ofthose involved in the chain of posses-sion, time and dates of possession,and other notations to trace samples.

D. Quality Assurance andQuality Control

To verify the accuracy of field samplingprocedures, you should collect field qualitycontrol samples, such as trip blanks, fieldblank, equipment blanks, spilt samples,blinds, and duplicates. Table 5 below sum-marizes these common types of QA/QC sam-ples. Analyze quality control samples for therequired monitoring parameters. OtherQA/QC practices include sampling equip-ment calibration, equipment decontamina-tion, and use of chain-of-custody forms.ASTM Guide D-5283 Standard Practice forGeneration of Environmental Data Related toWaste Management Activities: Quality Assuranceand Quality Control Planning andImplementation provides guidance on QA/QC

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Type of Sample Purpose Frequency


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Table 5 Types of QA/QC Samples

Trip BlankUsed for volatile organic com-pounds (VOCs) only. Trip blanksare prepared at the analyzing labo-ratory and transported to the fieldwith the empty vials to be used inthe VOC field sampling. They con-sist of a sealed vial filled with ana-lyte-free water (i.e., de-ionizedwater). The water should be thesame as the water the laboratorywill use in analyzing the actualsamples collected in the field, andinclude any preservatives or addi-tives that will be used. They arehandled, stored, and transportedin the exact same manner as thefield samples. Trip blanks shouldnever be opened in the field.

Field BlankA sample collected in the field byfilling a vial with analyte-free waterand all preservatives or additivesthat will be added to actual sam-ples. Field blanks should be pre-pared under the exact sameconditions in the same location asactual samples either in the middleor at the end of each samplingepisode. They also should be han-dled, stored, and transported inthe exact same manner as the actu-al samples.

Equipment BlankA sample prepared by pouringanalyte-free water through or overa decontaminated piece of sam-pling equipment. The blankshould be prepared on site.Equipment blanks should be han-dled, stored, and transported inthe exact same manner as the actu-al samples.

Trip blanks provide a quality assur-ance test for detecting contaminationfrom improper sample container(vial) cleaning prior to shipping tothe field, the use of contaminatedwater in analyzing the samples inthe laboratory, VOC contaminationoccurring during sample storage ortransport, and any other environ-mental conditions that could resultin VOC contamination of samplesduring the sampling event.

Field blanks are used to evaluate theeffects of onsite environmental conta-minants, the purity of the preserva-tives and additives used, and generalsample collecting and container filling.

Equipment blanks are used to deter-mine the effectiveness of the fieldcleaning of sampling equipment.Generally, they are necessary whensampling equipment must becleaned in the field and reused forsubsequent sampling.

One trip blank for each coolerused during a sampling episodeshould be prepared for eachvolatile organic method to be usedin the field. For example, if 2volatile organic methods are to beused over 2 days with samplesbeing sent to the lab at the end ofeach day, then a total of 4 tripblanks would be needed (i.e., Day1: 1 cooler with samples from 2methods = 2 trip blanks; Day 2: 1cooler with samples from 2methods = 2 trip blanks; total tripblanks = 4).

One field blank should beprepared for each parameter beingsampled and analyzed per day, orat a rate of 5 percent of thesamples in a parameter group perday, whichever is larger. Forexample if 3 parameter groupswere to be sampled over 2 daysthen 6 field blanks would berequired (i.e., 3 parameter groupsx 2 days = 6 field blanks).

At least one equipment blankshould be prepared for each pieceof equipment used in samplingthat must be field cleaned. Eachtime an equipment blank isrequired, a sample should beprepared for each parameter groupbeing assessed. For example, ifsamples are taken for 3 parametergroups, and a piece of samplingequipment requires cleaning then atotal of 3 equipment blanks will berequired for each required cleaning(i.e., 1 piece of equipment x 3parameter groups = 3 equipmentblanks per cleaning).

planning and implementation for waste man-agement activities. Chapter 1 of SW-846 alsoprovides guidance on QA/QC practices.

E. Analytical ProtocolsMonitoring programs should employ ana-

lytical methods that accurately measure theconstituents being monitored. SW-846 rec-ommends specific analytical methods to testfor various constituents. Similarly, individualstates might recommend other analyticalmethods for analysis.

Ensure the reliability and validity of analyt-ical laboratory data as part of the monitoring

program. Most facility managers use commer-cial laboratories to conduct analyses of sam-ples; others might use their own internallaboratories if they are equipped and qualifiedto perform such analyses. In selecting an ana-lytical laboratory, check for the following: lab-oratory certification by a state or professionalassociation for the type of analyses needed;qualified lab personnel; good quality analyti-cal equipment with back-up instrumentation;a laboratory QA/QC program; proper lab doc-umentation; and adherence to standard proce-dures for data handling, reporting, and recordkeeping. Laboratory QA/QC programs shoulddescribe chain-of-custody procedures, calibra-tion procedures and frequency, analytical

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Type of Sample Purpose Frequency

Table 5 Types of QA/QC Samples (cont.)

Split (Replicate) SampleA sample that is divided into 2 ormore containers and sent foranalysis by separate laboratories.

DuplicatesSamples collected simultaneouslyfrom the same source under identi-cal conditions (e.g., same type ofsampling techniques and equip-ment).

BlindsA sample prepared prior to a sam-pling episode by the laboratory oran independent source. The blindcontains a specific amount of ana-lyte known by the preparer, butthat is unknown to the analyst atthe time of analysis.

Split samples are used to assess sam-pling and analytical techniques.Samples can be divided into por-tions (split) at different points in thesampling and analysis process toassess the precision of various com-ponents of the sampling and analysissystem. For example, a sample splitin the field (field replicate) is used toassess sample storage, shipment,preparation, analysis, and datareduction. A sample split just priorto laboratory analysis (analysis repli-cate) is used to assess the precisionof analytical instrumentation.

Duplicate samples are used to assessthe precision of sampling techniquesand laboratory equipment.

Blinds are used to validate the accu-racy and precision of the analyzinglaboratories sample analyses.

(No guidance on frequencyprovided)



standard operating procedures, and data vali-dation and reporting procedures. A goodQA/QC program helps ensure the accuracy oflaboratory data.

VI. Analysis ofMonitoring Data,ContingencyPlanning, andAssessmentMonitoring

Once monitoring data have been collected,the data are analyzed to determine whethercontaminants are migrating from a waste man-agement unit. You should develop a contin-gency plan to address the situations wherecontamination is detected.

A. Statistical ApproachesStatistical procedures should be used to

evaluate monitoring data and determine ifthere is evidence of a release from a wastemanagement unit. Anomalous data can resultfrom sampling uncertainty, laboratory error, orseasonal changes in natural site conditions.Qualified statistical professionals can deter-mine if statistically significant changes haveoccurred or whether the quantified differencescould have arisen solely because of one of theabove-listed factors. Selecting the appropriatestatistical method is very important to avoidgenerating false positive or false negatives. Inmonitoring groundwater, for example, theselection of the appropriate statistical methodwill be contingent upon an adequate reviewand evaluation of the background groundwa-ter data. These data should be evaluated forproperties such as independence, trends,detection frequency and distribution (e.g.,

normal or lognormal). Examples of two statis-tical approaches include inter-well (upgradientvs. downgradient) or intra-well comparisons.After consulting with the state agency and sta-tistical professional and selecting a statisticalapproach, continue to use the selectedmethod in all statistical analyses. Do notswitch to a different test when the firstmethod generates unfavorable results.

What is important in selecting a

statistical approach?

An appropriate statistical approach willminimize false positives or negatives in termsof potential releases. The approach shouldaccount for historical data, site conditions,site operating practices, and seasonal varia-tions. While there are numerous statisticalapproaches used to evaluate monitoring data,check with the state to determine if a specificstatistical approach is recommended.

Common methods for evaluating monitoringdata include the following statistical approaches:

• Tolerance intervals. Tolerance inter-vals are statistical intervals construct-ed from data designed to contain aportion of a population, such as 95percent of all sample measurements.

• Prediction intervals. These intervalsapproximate future sample valuesfrom a population or distributionwith a specific probability. Prediction


9-45

intervals can be used both for com-parison of current monitoring data toprevious data for the same site.

• Control charts. These charts use his-torical data for comparison purposesand are, therefore, only appropriatefor initially uncontaminated sites.

There are many different ways to select anappropriate statistical method. For moredetailed guidance on statistical methods forground-water contaminant detection moni-toring, consult Addendum to Interim FinalGuidance Document on Statistical Analysis ofGround-Water Monitoring Data at RCRAFacilities (U.S. EPA, 1993); GuidanceDocument on Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities-Interim Final Guidance (U.S. EPA, 1989); andASTM provisional guide PS 64- 96 in theAnnual Book of ASTM Standards.

B. Contingency PlanningContingency plans identify the procedures

to follow if a statistically significant change inone or more constituents has been detected.A contingency plan should include proce-dures to determine whether a change in sam-ple concentrations was caused by the wastemanagement unit or by unrelated factors;procedures for developing and conducting anassessment monitoring program; proceduresfor remediating the waste management unitto stop the release of contaminants; and adetermination of the magnitude of contami-nation that would require initiation of correc-tive action, such as a statistical exceedance ofan HBN, an MCL for surface or groundwater, or a site-specific risk-based number.

C. Assessment MonitoringThe purpose of assessment monitoring is

to evaluate the rate, extent, and concentra-

tions of contamination. Once a statisticallysignificant change has been confirmed forone or more of the sampling parameters, youshould determine whether the change wascaused by factors unrelated to the unit.Factors unrelated to the unit that might causea change in the detected concentration(s) are:

• Contaminant sources other than thewaste management unit being moni-tored.

• Natural variations in the quality ofthe media being monitored.

• Analytical errors.

• Statistical errors.

• Sampling errors.

If the change was caused by a factor unre-lated to the unit, then additional measuresmight not be necessary and the original mon-itoring program can be resumed. If, however,these factors have been ruled out, you shouldbegin an assessment monitoring program.You should consult with the state agency todetermine the type of assessment monitoringto conduct at the unit. Assessment monitor-ing typically involves resampling at all sites,and analyzing the samples for a larger list ofparameters than used during the basic moni-toring program. More than one samplingevent might be necessary and additionalmonitoring might need to be performed toadequately determine the scope or extent ofany contamination. It is recommended thatyou work with state officials to establishbackground concentrations and protectionstandards for all additional constituents thatwere detected during assessment monitoring.

If assessment monitoring results indicatethere is not a statistically significant changein the concentrations of one or more of theconstituents over the established protectionstandards, then you can resume the originalmonitoring program. If, however, there is a

9-46


statistically significant change in any of theseconstituents, consult with state officials toidentify the next steps. It might be necessaryto perform additional monitoring to charac-terize the nature and extent of the contamina-tion and to notify persons who own or resideon any land directly impacted by the contam-ination if it has migrated beyond the facilityboundary.

Detection of contamination can be an indi-cator that the waste management unit’s con-tainment system is not working properly.During this assessment phase, component(s)of the unit (cover, liner, or leachate collectionsystem) that are not working properly shouldbe identified and, if possible, remediated. Forexample, sometimes sealing a hole in theliner of a small surface impoundment can besufficient to stop the source of contamination.Other times, more extensive response mightbe required. One example could be theextensive subsidence of a unit’s final covercreating the need for repair. In some cases,liner and leachate collection system repairsmight not be possible, such as in a large sur-face impoundment or a landfill with severaltons of waste already in place. If remediationis not possible, consult with state officialsabout beginning assessment monitoring andconsult Chapter 10–Taking Corrective Action.


9-47

You should consider the following for each media when developing a monitoring program for industrialwaste management units:

Ground Water

■■■■ Perform a site characterization, including investigation of the site’s geology, hydrology, and subsur-face hydrogeology to determine areas for ground-water monitoring; select parameters to be moni-tored based on the characteristics of the waste managed.

■■■■ Identify qualified engineers and ground-water specialists to assist in designing and operating theground-water monitoring program.

■■■■ Consult with qualified professionals to identify necessary program components including the mon-itoring well design, the number of monitoring wells, the lateral and vertical placement of the wells,the duration and frequency of monitoring, and the appropriate sampling parameters.

■■■■ Determine the appropriate method(s) of ground-water monitoring, including conventional wellmonitoring, direct push sampling, geophysical monitoring, and vadose zone monitoring as possi-bilities.

■■■■ Use qualified laboratories to analyze samples.

Surface Water

■■■■ Collect and analyze samples according to the requirements of a site’s federal or state storm-waterpermit.

■■■■ If not subject to permit requirements, implement a storm-water sampling program to monitor thequality of runoff and determine the effectiveness of BMPs.

■■■■ If applicable, collect and analyze discharges to POTWs according to any requirements of a localpretreatment program.

■■■■ Implement a surface-water sampling program to monitor water quality and determine the effec-tiveness of BMPs.

■■■■ Perform regular inspections and maintenance of surface-water protection measures and BMPs toreduce the potential for surface-water contamination.


Soil Monitoring

■■■■ Determine the number and location of samples needed to adequately characterize soil according tothe variability of the soil at a site.

■■■■ Follow established soil-sampling procedures to obtain meaningful results.


Monitoring Performance Activity List

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9-49

■■■■ Determine baseline soil conditions by sampling prior to waste application.

■■■■ Collect and analyze samples at regular intervals to detect contaminant problems.

Air Monitoring

■■■■ Use the Industrial Waste Air (IWAIR) Model to evaluate risks from VOC emissions.

■■■■ Use an alternative emissions model if the IWAIR Model indicates a problem with VOC emission oris not appropriate for your site.

■■■■ If collecting air monitoring data, determine the type of monitoring necessary to evaluate the effec-tiveness of air pollution control techniques employed on site or for input into air emissions anddispersion models.

■■■■ Select the proper test methods.

■■■■ Establish guidelines to ensure the quality of the data collected prior to implementing an air moni-toring program.

■■■■ Consult with air modeling professionals, state and local air quality offices, EPA regional air pro-gram offices, or EPA’s Office of Air Quality Planning and Standards before implementing an airmonitoring program or choosing an alternative emission model to evaluate risks.


Sampling and Analytical Protocols QA/QC

■■■■ Develop sample collection, preservation, storage, transport, and handling protocols tailored to dataneeds, and establish quality assurance and quality control procedures to check the accuracy of themonitoring samples.

■■■■ Eliminate cross-contamination or background contamination of any samples by purging the wells,using appropriate sampling equipment, and ensuring that any unstable parameters, such as pH,dissolved oxygen, and temperature, have been tested at the site.

■■■■ Identify the appropriate analytical methods and statistical approach for the sampling data includ-ing parametric analysis of variance (ANOVA), tolerance intervals, prediction intervals, and controlcharts as possibilities.

■■■■ Evaluate the need for assessment monitoring and abatement.

Monitoring Performance Activity List (cont.)

Site Characterization

American Society for Testing and Materials. 2001. Annual Book of ASTM Standards. ASTM.

American Society for Testing and Materials. 1994. ASTM Standards on Ground Water and Vadose ZoneInvestigations, 2nd Edition. ASTM.

ASTM D-1452. 1980. Practice for Soil Investigation and Sampling by Auger Borings.

ASTM D-1586. 1984. Test Method for Penetration Test and Split-Barrel Sampling of Soils

ASTM D-1587. 1983. Practice for Thin-Walled Tube Sampling of Soils.

ASTM D-3550. 1988. Practice for Ring-Lined Barrel Sampling of Soils..

ASTM D-4220. 1989. Practices for Preserving and Transporting Soil Samples.

ASTM D-5792. 1995. Standard Practice for Generation of Environmental Data Related to Waste ManagementActivities: Development of Data Quality Objectives.

Boulding, J.R. 1995. Practical Handbook of Soil, Vadose Zone, and Ground Water Contamination:Assessment, Prevention and Remediation. Lewis Publishers.

CCME. 1994. Subsurface Assessment Handbook for Contaminated Sites, CCME EPC-NCSRP-48E, CanadianCouncil of Ministers of the Environment.

Morrison, R.D. 1983. Groundwater Monitoring Technology. Timco Mfg. Inc.

Sara, M.N. 1994. Standard Handbook for Solid and Hazardous Waste Facility Assessments. Lewis Publishers.

Topp, G.C. and J.L. Davis. 1985. “Measurement of Soil Water Using Time-Domain Reflectometry (TDR): AField Evaluation,” Soil Science Society of America Journal. 49:19-24.

U.S. EPA. 1993. Subsurface Characterization and Monitoring Techniques: A Desk Reference Guide. Volume I:Solids and Ground Water, Appendices A and B. EPA625-R-93-003a.

U.S. EPA. 1993. Subsurface Characterization and Monitoring Techniques: A Desk Reference Guide. Volume II:The Vadose Zone, Field Screening and Analytical Methods, Appendices C and D. EPA625- R-93-003b.

Resources

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9-51

U.S. EPA. 1988. Criteria for Municipal Solid Waste Landfills: Draft background Document. EPA530- SW-88-042.

U.S. EPA. 1987. DRASTIC: A Standardized System for Evaluating Ground Water Pollution Potential UsingHydrogeologic Settings. EPA600-2-87-035.

Wilson, L.G., L.G. Everett, and S.J. Cullen (eds.). 1995. Handbook of Vadose Zone Characterization andMonitoring. Lewis Publishers.

Ground-Water Monitoring Well Design, Installation, and Development

Cullen, S.J. 1995. Vadose Zone Monitoring: Experiences and Trends in the United States. Ground WaterMonitoring Review 15(3):136-143.

Cullen, S.J., J.K. Kramer, and J.R. Luellen. 1995. A Systematic Approach to Designing a MultiphaseUnsaturated Zone Monitoring Network. Ground Water Monitoring Review 15(3):124-135.

Geoprobe Systems. 1996. Geoprobe Prepacked Screen Monitoring Well: Standard Operating Procedure.Technical Bulletin No. 96-2000.

Hayes, J.P. and D.C. Tight. 1995. Applying Electrical Resistance Blocks for Unsaturated Zone Monitoring atArid Sites. Handbook of Vadose Zone Characterization and Monitoring. L.G. Wilson, L.G. Everett, and S.J.Cullen (eds.). Lewis Publishers. pp. 387-399.

Kramer, J.H., S.J. Cullen, and L.G. Everett. 1992. Vadose Zone Monitoring with the Neutron MoistureProbe. Ground Water Monitoring Review 12(3):177-187.

Ohio Environmental Protection Agency. 1995. Technical Guidance Manual for HydrogeologicInvestigations and Ground Water Monitoring.

Robbins, G.A. and M.M. Gemmell. 1985. Factors Requiring Resolution in Installing Vadose ZoneMonitoring Systems. Ground Water Monitoring Review 5:76-80.

U.S. EPA. 1993a. Ground-Water Monitoring: Draft Technical Guidance. EPA530-R-93-001.

U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. Chapter 5. EPA530-R-93- 017.

U.S. EPA. 1991. Handbook: Ground Water. Volume II: Methodology. EPA625-6-90-016b.

Resources (cont.)

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U.S. EPA. 1990. Handbook: Ground Water. Volume I: Ground Water and Contamination.EPA625-6-90- 016a.

U.S. EPA. 1989. Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells. EPA600-4-89-034.

Sample Procedures

ASTM. D-5283. 1997. Standard Practice for Generation of Environmental Data Related to WasteManagement Activities: Quality Assurance and Quality Control Planning and Implementation.

Benson, R.C., R.A. Glaccum, and M.R. Noel. 1984. Geophysical Techniques for Sensing BuriedWastes and Waste Migration. EPA600-7-84-064.

Bond, W.R. 1995. Case Studies of Vadose Zone Monitoring and Sampling Using Porous SuctionCup Samplers. Handbook of Vadose Zone Characterization and Monitoring. L.G. Wilson, L.G.Everett, and S.J. Cullen (eds.). Lewis Publishers. pp. 523-532.

Federal Remediation Technologies Roundtable. 2001. Field Sampling and Analysis TechnologiesMatrix. Version 1.0. <www.frtr.gov/site>

Gibbons, R.D. 1990. Estimating the Precision of Ground-Water Elevation Data. Ground Water,28, 357- 360.

Minnesota Pollution Control Agency. 1995. Ground Water Sampling Guidance: Development ofSampling Plans, Protocols and Reports.

Texas Natural Resource Conservation Commission. 1994. TNRCC Technical Guidance:Guidelines for Preparing a Ground-Water Sampling and Analysis Plan (GWSAP).

Thomson, K.A. 1995. Case Studies of Soil Gas Sampling. Handbook of Vadose ZoneCharacterization and Monitoring. L.G. Wilson, L.G. Everett, and S.J. Cullen (eds.). LewisPublishers. pp. 569-588.

U.S. EPA. 1995a. Ground Water Sampling—A Workshop Summary. EPA600-R-94-205.

U.S. EPA. 1995b. Laboratory Methods for Soil and Foliar Analysis in Long-term EnvironmentalMonitoring Program. EPA600-R-95-077

Resources (cont.)


9-53

U.S. EPA. 1995c. Low Flow Ground-Water Sampling. EPA540-S-95-504.

U.S. EPA. 1994a. Industrial User Inspection and Sampling Manual for POTWs.

U.S. EPA. 1994b. Region VIII Guidance, Standard Operating Procedures for Field Sampling Activities.

U.S. EPA. 1992. NPDES Storm Water Sampling Guidance Document. EPA833-B-92-001.

U.S. EPA. 1991. Description and Sampling of Contaminated Soils: A Field Pocket Guide. EPA625-12-91-002

U.S. EPA. 1989. Interim Final RCRA Facility Investigation (RFI) Guidance: Volumes I-III. EPA530- SW-89-031.

U.S. EPA. 1986. Test Methods for Evaluating Solid Waste—Physical/Chemical Methods. EPA SW-846,3rd edition. PB88-239-233.

Surface Water Monitoring

Novotny, V., and H. Olem. 1994. Water Quality: Prevention, Identification, and Management of DiffusePollution. Van Nostrand Reinhold.

U.S. EPA. 1999. Introduction to the National Pretreatment Program. EPA833-B-98-002.

U.S. EPA. 1997. Volunteer Stream Monitoring Document. EPA841-B-97-003.

U.S. EPA. 1991. Volunteer Lake Monitoring Document. EPA440-4-91-002.

Soil Monitoring

Delaware Cooperative Extension Service. 1995. Recommended Soil Testing Procedures for theNortheastern United States. 2nd Edition. Northeastern Regional Publication No. 493.

North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling - The Key toReliable Soil Test Information. AG-439-30.

Rowell, D.L. 1994. Soil Science: Methods and Applications.

Soil Quality Institute of the National Resources Conservation Service, USDA. 2001. Guidelines for SoilQuality Assessment in Conservation Planning. <www.statlab.iastate.edu/survey/SQI/>

Resources (cont.)

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University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991.Guidelines for Soil Sampling. G91-1000-A. February. <www.ianr.unl.edu/pubs/soil/g1000.htm>

U.S. EPA. 1995d. Laboratory Methods for Soil and Foliar Analysis in Long-Term EnvironmentalMonitoring Programs. EPA600-R-95-077.

U.S. EPA. 1989. RCRA Facility Investigation Guidance: Volume II: Soil, Ground Water and SubsurfaceGas Releases. EPA530-SW-89-031

Air Monitoring

Boubel, R. W., D. L. Fox, D. B. Turner, and A. C. Stern. 1994. Fundamentals of Air Pollution. 3rdEdition. Academic Press.

Stull, Roland B. 1988. An Introduction to Boundary Layer Meteorology. Kluwer Academic Publishers.

Yoest, H. and R. W. Fitzgerald. February 1996. Chemical Engineering Progress. Stationary SourceTesting: The Fundamentals.

U.S. EPA. 1993. Air/Superfund National Technical Guidance Study Series: Compilation of Informationon Real-time Air Monitoring for Use at Superfund Sites. EPA451-R-93-008.

U.S. EPA. 1993. Air/Superfund National Technical Guidance Study Series: Volume 4: Guidance forAmbient Air Monitoring at Superfund Sites, Revised. EPA451-R-93-007.

U.S. EPA. 1990. Guidance on Applying the Data Quality Objectives Process for Ambient Air MonitoringAround Superfund Sites (Stages 1 and 2). EPA450-4-90-005.

U.S. EPA. 1990. Air/Superfund National Technical Guidance Study Series: Contingency Plans atSuperfund Sites Using Air Monitoring. EPA450-1-90-005.

U.S. EPA. 1989. Air/Superfund National Technical Guidance Study Series, Volume 4: Procedures forDispersion Modeling and Air Monitoring for Superfund Air Pathway Analysis, Interim Report, Final.EPA450-1-89-004.

U.S. EPA. 1986. Test methods for Evaluating Solid Waste. 3rd Edition. Office of Solid Waste andEmergency Response. SW-846.

Statistical References

Davis, C.B. and McNichols, R.J. 1987. One-Sided Intervals for at Least p of m Observations from aNormal Population on Each of r Future Occasions. Technometrics, 29, 359-370.

Resources (cont.)


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Gibbons, R.D. 1994. Statistical Methods for Ground-Water Monitoring. John Wiley & Sons.

Gibbons, R.D. 1992. An Overview of Statistical Methods for Ground-Water Detection Monitoring atWaste Disposal Facilities. In Ground-Water Contamination at Hazardous Waste Sites: Chemical Analysis.S. Lesge and R.E. Jackson (eds.), New York: Marcel Dekker, Inc.

Gibbons, R.D., Dolan, D., Keough, H., O’Leary, K., and O’Hara, R. 1992. A Comparison of ChemicalConstituents in Leachate from Industrial Hazardous Waste and Municipal Solid Waste Landfills.Proceedings of the Fifteenth Annual Madison Waste Conference, University of Wisconsin, Madison.

Gibbons, R.D., Gams, N.E., Jarke, F.H., and Stoub, K.P. 1992. Practical Quantitation Limits.Chemometrics and Intelligent Laboratory Systems, 12, 225-235.

Gibbons, R.D. 1991. Some Additional Nonparametric Prediction Limits for Ground-Water Monitoring atWaste Disposal Facilities. Ground Water, 29, 729-736.

Gibbons, R.D., Jarke, F.H., and Stoub, K.P. 1991. Detection Limits: For Linear Calibration Curves withIncreasing Variance and Multiple Future Detection Decisions. Waste Testing and Quality Assurance. 3,ASTM, SPT 1075, 377-390.

Gibbons, R.D. and Baker, J. 1991. The Properties of Various Statistical Prediction Limits. Journal ofEnvironmental Science and Health. A26-4, 535-553.

Gibbons, R.D. 1991. Statistical Tolerance Limits for Ground-Water Monitoring. Ground Water 29.

Gibbons, R.D. 1990. A General Statistical Procedure for Ground-Water Detection Monitoring at WasteDisposal Facilities. Ground Water, 28, 235-243.

Gibbons, R.D., Grams, N.E., Jarke, F.H., and Stoub, K.P. 1990. Practical Quantitation Limits.Proceedings of Sixth Annual U.S. EPA Waste Testing and Quality Assurance Symposium. Vol. 1, 126-142.

Gibbons, R.D., Jarke, F.H., and Stoub, K.P. 1989. Methods Detection Limits. Proceedings of Fifth AnnualU.S. EPA Waste Testing and Quality Assurance Symposium. Vol. 2, 292-319.

Gibbons, R.D. 1987. Statistical Prediction Intervals for the Evaluation of Ground-Water Quality. GroundWater, 25, 455-465.

Resources (cont.)

Gibbons, R.D. 1987. Statistical Models for the Analysis of Volatile Organic Compounds in WasteDisposal Facilities. Ground Water 25, 572-580.

Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. Van Nostrand Reinhold,New York.

Starks, T.H. 1988. Evaluation of Control Chart Methodologies for RCRA Waste Sites. U.S. EPA TechnicalReport CR814342-01-3.

Patil, G.P. and Rao, C.R. eds, Elsevier. 1993. Handbook of Statistics, Vol 12: Environmental Statistics.

U.S. EPA. 1993. Addendum to Interim Final Guidance Document Statistical Analysis of Ground-WaterMonitoring Data at RCRA facilities. EPA530-R-93-003.

U.S. EPA. 1989. Guidance Document on Statistical Analysis of Ground-Water Monitoring Data at RCRAFacilities–Interim Final Guidance.

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Resources (cont.)


Chapter 10Taking Corrective Action

Contents

I. Corrective Action Process........................................................................................................................10-1

A. Unit Assessment ....................................................................................................................................10-2

B. Unit Investigation ..................................................................................................................................10-4

1. Specific Considerations for Ground-Water Investigations ..................................................................10-5

2. Specific Considerations for Soil Investigations ..................................................................................10-6

3. Specific Considerations for Surface-Water Investigations ..................................................................10-6

4. Specific Consideration for Air-Release Investigations ........................................................................10-7

C. Interim Measures ..................................................................................................................................10-8

D. Evaluating Potential Corrective Measures ............................................................................................10-10

1. Meeting Cleanup Standards ............................................................................................................10-11

2. Evaluating Treatment Technologies ..................................................................................................10-12

3. Evaluating the Long- and Short-Term Effectiveness of the Remedy..................................................10-18

4. Evaluating the Effectiveness of Reducing or Eliminating the Source of Contamination ....................10-19

5. Evaluating the Ease of Implementation ............................................................................................10-19

6. Measuring the Degree to Which Community Concerns are Met ......................................................10-20

E. Implementing Corrective Measures ......................................................................................................10-20

1. Institutional Controls ......................................................................................................................10-20

2. Monitoring and Site Maintenance ....................................................................................................10-22

3. No Further Action and Site Closure ................................................................................................10-22

Taking Corrective Action Activity List ........................................................................................................10-23

Resources ....................................................................................................................................................10-24

Figures:

Figure 1. Corrective Action Process............................................................................................................10-2

Figure 2. Screening Process for Selecting Appropriate Treatment Technologies ........................................10-17

Tables:

Table 1 Factors To Consider in Conducting a Unit Assessment ..................................................................10-3

Table 2 Chemical Characteristics................................................................................................................10-3

Table 3 Site Characteristics ........................................................................................................................10-4

Table 4 Potential Release Mechanisms for Various Unit Types ....................................................................10-7

Table 5 Examples of Interim Corrective Measures ......................................................................................10-8

Ensuring Long-Term Protection—Taking Corrective Action

10-1

Effective operation of a waste man-agement unit involves checkingthe performance of the waste man-agement system components.When components are not operat-

ing effectively or when a problem develops,corrective action might be needed to protecthuman health and the environment.Corrective action involves identifying expo-sure pathways of concern, selecting the bestcorrective measure to achieve the appropriatecleanup standard, and consulting with stateand community representatives.

I. CorrectiveAction Process

The purpose of a corrective action programis to assess the nature and extent of the releas-es of waste or constituents from the wastemanagement unit(s); to evaluate unit charac-teristics; and to identify, evaluate, and imple-ment appropriate corrective measures toprotect human health and the environment.The overall goal of any corrective actionshould be to achieve a technically and eco-nomically feasible cleanup standard at a speci-fied point on the facility property. For newfacilities this point should be on facility prop-erty, no more than 150 meters from the wastemanagement unit boundary (as established inChapter 9–Monitoring Performance). Existingfacilities can either use this same 150 metermonitoring point standard or work with theirstate agencies to determine an alternate set ofacceptable monitoring and cleanup criteria.Using the ground-water pathway as an exam-ple, the corrective action goal should be toreduce constituent concentration levels to theapplicable maximum contaminant levels(MCLs) or health based numbers at the moni-

Taking Corrective ActionThis chapter will help you:

• Monitor the performance of a waste management unit and take

appropriate steps to remediate any contamination associated

with its operation.

• Locate and characterize the source of any contamination.

• Identify and evaluate potential corrective measures.

• Select and implement corrective measures to achieve attainment

of the established cleanup standard.

• Work closely with the state and community representatives.

This chapter will help address the follow-ing questions.

• What steps are associated with correc-tive action?

• What information should be collectedduring investigations?

• What factors should be considered inselecting an appropriate corrective mea-sure?

• What is involved in implementing theselected remedy?

10-2


toring point (i.e., for new units, no more than150 meters from the waste management unit).

A corrective action program generally hasthe components outlined here and in Figure1 (and explained in greater detail below). Thedetail required in each of these componentsvaries depending on the unit and its com-plexity and only those tasks appropriate foryour site should be conducted. We recom-mend that you coordinate with the state dur-ing all phases of corrective action.

• Perform a unit assessment to locatethe actual or potential source(s) ofthe release(s) of contaminants basedon waste management unit monitor-ing information and the use of otherexisting information.

• Perform a unit investigation to char-acterize the nature and extent of con-tamination from the unit and anycontamination that might be migrat-ing beyond the facility boundary,identify areas and populations threat-ened by releases from the unit, anddetermine short- and long-termthreats of releases from the unit tohuman health and the environment.

• Identify, evaluate, and implementinterim measures, if needed. Interimmeasures are short-term actionstaken to protect human health andthe environment while a unit assess-ment or a unit investigation is beingperformed or before a correctivemeasure is selected.

• Identify, evaluate, and implementcorrective measures to abate the fur-ther spread of contaminants, controlthe source of contamination, and toremediate releases from the unit.

• Design a program to monitor themaintenance and performance of anyinterim or final corrective measures

to ensure that human health and theenvironment are being protected.

A. Unit AssessmentOften the first activity in the corrective

action process is the unit assessment. A unitassessment identifies potential and actualreleases from the unit and makes preliminarydeterminations about release pathways, theneed for corrective action, and interim mea-sures. If appropriate, evaluate the possibilityof addressing mul-tiple units as thecorrective actionprocess proceeds.Table 1 identifies anumber of factorsto consider duringa unit assessment.Tables 2 and 3 pre-sent some usefulproperties andparameters thatdefine chemical

Unit Assessment

Unit Investigation

Interim Measures

Corrective MeasuresEvaluation

Corrective MeasuresImplementation

Figure 1 Corrective Action Process


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Unit/Site Chemical Migration Evidence of Release ExposureCharacteristics Characteristics Pathways Potential

Table 1Factors To Consider in Conducting a Unit Assessment

ContaminationParameters– Concentrations– Depth and location of

contamination

Physical Parameters– Geology– Depth to ground water– Flow characteristics– Climate

Historical Information– History of unit– Knowledge of waste

generation practices

Type of wasteplaced in the unit

Volatilizationparameters

Toxicologicalcharacteristics

Physical andchemical properties

Chemical class

Soil sorption/degradationparameters

Facility’sgeologicalsetting

Facility’shydrogeologicalsetting

Atmosphericconditions

Topographiccharacteristics

Manmadefeatures (e.g.,pipelines,undergroundutility lines)

Prior inspection reports

Citizen complaints

Monitoring data

Visual evidence, such asdiscolored soil, seepage,discolored surface wateror runoff

Other physical evidencesuch as fish kills,worker illness, or odors

Sampling data

Offsite water wells

Proximity toaffectedpopulation

Proximity tosensitiveenvironments

Likelihood ofmigration topotentialreceptors

Property/Parameter Characteristics

Chemical properties Density, viscosity

Chemical class Acid, base, polar neutral, nonpolar neutral, inorganic

Chemical reactivity Oxidation, reduction, hydrolysis, polymerization, precipitation,biotic/abiotic

Soil sorption parameters Cation exchange capacity, anion exchange capacity, soil/waterpartition coefficient (Kd), octanol/water partition coefficient(Kow)

Soil degradation parameters Half-life, intermediate products of degradation

Volatilization parameters Henry’s law constant, vapor pressure

Table 2Chemical Characteristics

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and site characteristics that you should consid-er when characterizing your site and environ-mental setting.

A beginning step is to review available siteinformation regarding unit characteristics,waste characteristics, contaminant migrationpathways, evidence of release, and exposurepotential. Much of this information shouldhave been gathered in the site assessment (seeChapter 4–Considering the Site) and wastecharacterization phases (see Chapter2–Characterizing Waste). Conducting a visualsite inspection of the unit will re-affirm avail-able information and enable you to note anyvisual evidence of releases. If necessary, per-form sampling to confirm or disprove suspect-ed releases before performing an extensive unitinvestigation.

B. Unit InvestigationA unit investigation is conducted after a

release from the operating unit has been con-firmed. The purpose of the investigation is togather enough data to fully characterize thenature, extent, and rate of migration of conta-minants to determine and support the selec-

tion of the appropriate response action. It isimportant to tailor unit investigations to spe-cific conditions and circumstances at the unitand focus on releases and potential pathways.Although each medium will require specificdata and methodologies to investigate arelease, a general strategy for this investigation,consisting of two elements, can be describedas follows.

• Collect and review monitoring data,data which can be gathered from out-side information sources on parame-ters affecting the release, or newinformation such as aerial photogra-phy or waste characterization.

• Formulate and implement field inves-tigations and sampling and analysis ormonitoring procedures designed toverify suspected releases. Evaluate thenature, extent, and rate of migration ofverified releases. Refer to Chapter9–Monitoring Performance to helpdesign a monitoring program.

Detailed knowledge of source characteristicsis valuable in identifying constituents forwhich to monitor, indicator parameters, and

Parameter/Information Characteristics

Contamination parameters Concentration in soil, water, and subsurface gas; depth andlocation of contamination

Physical parameters Permeability, particle size distribution, organic matter, geology,moisture content, flow characteristics, depth to ground water,pH, wind directions, climate

Historical information History of the waste management unit, knowledge of wastegeneration processes, waste quantity

Table 3Site Characteristics

Additional information on performing unit assessments can be found in RCRA Facility AssessmentGuidance (U.S. EPA, 1986).


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possible release pathways. It is also helpful inlinking releases to a particular unit.Monitoring information collected by a pro-gram described in Chapter 9–MonitoringPerformance can be helpful. Waste and unitcharacteristics can also provide informationfor determining release rates and for deter-mining the nature and scope of any correctivemeasures which might be applied. Refer toChapter 2–Characterizing Waste for informa-tion on how to characterize a waste.

Unit investigations can result in significantamounts of data, including the results ofchemical, physical, or biological analyses. Thiscan involve analyses of many constituents, indifferent media, at various sampling locations,and at different times. Data management pro-cedures should be established to effectivelyprocess these data such that relevant datadescriptions, such as sample numbers, loca-tions, procedures, and methods, are readilyaccessible and accurately maintained.

1. Specific Considerations forGround-Water Investigations

To facilitate ground-water investigationsconsider the following parameters:

• Ability of the waste to be dissolved orto appear as a distinct phase.

• Degradability of the waste and itsdecomposition products.

• Geologicandhydrolog-ic factorswhichaffect thereleasepathway.

• Regionaland site-specificground-waterflowregimesthat might affect the potential magni-tude of the release pathways and possi-ble exposure routes.

Exposure routes of concern include inges-tion of ground water as drinking water andnear-surface flow of contaminated groundwater into basements of residences or other

Guidance on PerformingUnit Investigations

Additional guidance on performingunit inspections can be found in the fol-lowing EPA documents:

• RCRA Facility Investigation GuidanceVolume I: Development of an RFI WorkPlan and General Considerations forRCRA Facility Investigations (U.S. EPA,1989a)

• RCRA Facility Investigation GuidanceVolume II: Soil, Ground Water, andSubsurface Gas Releases (U.S. EPA,1989b)

• RCRA Facility Investigation GuidanceVolume III: Air and Surface WaterReleases (U.S. EPA, 1989c)

• RCRA Facility Investigation GuidanceVolume IV: Case Study Examples (U.S.EPA, 1989d)

• Guidance for Conducting RemedialInvestigations and Feasibility StudiesUnder CERCLA (U.S. EPA, 1988a)

• Draft Practical Guide for Assessing andRemediating Contaminated Sites (U.S.EPA, 1989f)

• Site Characterization for SubsurfaceRemediation (U.S. EPA, 1991c)

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structures. It is important to also address thepotential for the transfer of contaminants inground water to other environmental mediathrough processes such as discharge to surfacewater and volatilization to the atmosphere.

Use existing ground-water monitoring infor-mation, where it exists, to determine thenature, extent, and rate of contaminant releasefrom the unit(s) to the ground water.Investigation of a suspected release might beterminated based on results from an initialmonitoring phase if these results show that anactual release has not, in fact, occurred. If,however, contamination is found, you shouldcharacterize the release through subsequentmonitoring to help determine the detailed con-stituent composition and concentrations, thehorizontal and vertical extent of the contami-nant release, as well as its rate of migration asappropriate to assess the risk. This should beaccomplished through direct sampling andanalysis and, when appropriate, can be supple-mented by indirect means such as geophysicalassessment and fate and transport modeling.

2. Specific Considerations for SoilInvestigations

When performing soil investigations, con-sider the following parameters:

• Ability of the waste to be dissolved byinfiltrating precipitation.

• The waste’s affinity for soil particles.

• The waste’s degradability and itsdecomposition products.

• Surface features such as topography,erosion potential, land-use potential,and vegetation.

• Stratigraphic/hydrologic features suchas soil profile, particle-size distribution,hydraulic conductivity, pH, porosity,and cation exchange capacity.

• Meteorological factors such as temper-ature, precipitation, runoff, and evap-otranspiration.

Relevant physical and chemical properties ofthe soil should be assessed to help determinepotential mobility of any contaminants in thesoil. Also, consider the potential for transfer ofcontaminants in the soil to other environmentalmedia such as overland runoff to surface water,leaching to ground water, and volatilization tothe atmosphere. In addition, you should estab-lish whether a potential release involved apoint source (localized) or a non-point source.Point sources might include container handlingand storage areas, tanks, waste piles, and bulkchemical transfer areas. Non-point sourcesmight include airborne particulate contamina-tion originating from a land application unitand widespread leachate seeps from a landfill.Table 4 presents important mechanisms of con-taminant release to soils for various unit types.This information can be used to identify areasfor initial soil monitoring.

3. Specific Considerations forSurface-Water Investigations

When conducting surface-water investiga-tions, the following factors should be consid-ered:

• The release mechanism, such as over-topping of an impoundment.


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• The nature of the source area, such aspoint or non-point.

• Waste type and degradability.

• Local climate.

• Hydrologic factors such as streamflow conditions.

• The ability for a contaminant to accu-mulate in stream bottom sediments.

Also, address the potential for the transferof contaminants in surface water to other

environmental media such as soil contamina-tion as a result of flooding of a contaminatedcreek on the facility property.

During the initial investigation, particularattention should be given to sampling runofffrom contaminated areas, leachate seeps, andother similar sources of surface-water contami-nation, as these are the primary overland releasepathways for surface water. Releases to surfacewater via ground-water discharge should beaddressed as part of the ground-water investiga-tion for greater efficiency. See Chapter9–Monitoring Performance, Section II: Surface-Water Monitoring for information on propersurface-water monitoring techniques.

4. Specific Consideration for Air-Release Investigations

The intent of an air-release investigation isto determine any actual or potential effects ata nearby receptor. This might involve emis-

Unit Type Release Mechanism

Surface impoundment Releases from overtopping

Leakage through dikes or unlined portions to surrounding soils

Landfill Migration of releases outside the unit’s runoff collection and containmentsystem

Seepage through underlying soils

Waste pile Migration of releases outside the unit’s runoff collection and containmentsystem

Seepage through underlying soils

Land application unit Migration of runoff outside the application area

Passage of leachate into the soil horizon

Table 4Potential Release Mechanisms for Various Unit Types

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sion modeling to estimate unit-specific emis-sion rates, air monitoring to determine con-centrations at a nearby receptor, emissionmonitoring at the source to determine emis-sion rates, and dispersion modeling to esti-mate concentrations at a nearby receptor. SeeChapter 9–Monitoring Performance, SectionIV: Air Monitoring for more information onair monitoring and Chapter 5–Protecting Airfor more information on air modeling.

As in other media-specific investigations,the first step is to collect, review, and evaluateavailable waste, unit, environmental setting,and release data. Evaluation of these data canindicate the need for corrective measures orthat no further action is required. For exam-ple, the source might involve a large, activestorage surface impoundment containingvolatile constituents adjacent to residentialhousing. Action, therefore, instead of furtherstudies, might be appropriate. Another case

might involve a unit in an isolated location,where an acceptable modeling or monitoringdatabase indicates that the air release can beconsidered insignificant and, therefore, fur-ther studies are not warranted. In manycases, however, further release characteriza-tion might be necessary.

C. Interim MeasuresMany cleanup programs recognize the

need for interim measures while site charac-terization is underway or before a final reme-dy is selected. Typically, interim measures areused to control or abate ongoing risks beforefinal remedy selection. Examples of interimmeasures for various types of waste manage-ment units and various release types are list-ed in Table 5. More information is availablethrough the RCRA Corrective Action InterimMeasures Guidance—Interim Final (U.S. EPA,

Unit/Release Interim Measure

Containers Overpack or redrumConstruct storage areaMove to new storage areaSegregationSampling and analysisTreatment or storageTemporary cover

Tanks Construct overflow/secondary containmentLeak detection or repairPartial or complete removal

Surface Impoundments Reduce headRemove free liquids and highly mobile wastesStabilize or repair side walls, dikes, or liner(s)Temporary coverRun-on or runoff control (diversion or collection devices)Sample and analyze to document the concentration of constituentsInterim ground-water measures

Table 5Examples of Interim Corrective Measures


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Unit/Release Interim Measure

Landfills Run-on or runoff control (diversion or collection devices)Reduce head on liner or leachate collection and removal systemInspect leachate collection and removal system, or french drainRepair leachate collection and removal system, or french drainTemporary capWaste removalInterim ground-water measures

Waste Piles Run-on or runoff control (diversion or collection devices)Temporary coverWaste removalInterim ground-water measures

Soils Sampling or analysisRemoval and disposalRun-on or runoff control (diversion or collection devices)Temporary cap or cover

Ground Water Delineation or verification of gross contaminationSampling and analysisInterceptor trench, sump, or subsurface drainPump-and-treatIn situ treatmentTemporary cap or cover

Surface-Water Releases Overflow or underflow dams(Point and Non-Point) Filter fences

Run-on or runoff control (diversion or collection devices)Regrading or revegetationSample and analyze surface waters and sediments or point source discharges

Gas Mitigation Control BarriersCollectionTreatmentMonitoring

Particulate Emissions Truck wash (decontamination unit)RevegetationApplication of dust suppressant

Other Actions Fencing to prevent direct contactSampling offsite areasAlternate water supply to replace contaminated drinking waterTemporary relocation of exposed populationTemporary or permanent injunction

Table 5Examples of Interim Corrective Measures (cont.)

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1988b) and RCRA Corrective ActionStabilization Technologies (U.S. EPA, 1992b).Interim measures can be separate from thecomprehensive corrective action plan, butshould be consistent with and integrated intoany longer term corrective measure. To theextent possible, interim measures should notseriously complicate the ultimate physicalmanagement of wastes or constituents, norshould they present or exacerbate a health orenvironmental threat.

D. Evaluating PotentialCorrective Measures

The corrective measure or measures select-ed should meet the corrective action goals,such as a state or local cleanup standard, andcontrol or remove the source of contamina-tion to reduce or eliminate further releases.Most corrective measures fall into one ofthree technology categories—containmenttechnologies, extraction or removal technolo-gies, or treatment technologies. The perfor-mance objectives of the corrective measuresrelate to source reduction, cleanup goals, andcleanup timeframe. These measures mightinclude the repair or upgrade of existing unitcomponents, such as liner systems, leachatecollection systems, or covers.

You should base selection of correctivemeasures on the following considerations andcontact the state and community representa-tives before finalizing the selection:

• The ability to meet appropriatecleanup standards.

• The appropriateness and effectivenessof the treatment technology in rela-tion to waste and site characteristics.

• The long- and short-term effectivenessincluding economic, technical feasibil-ity, and protectiveness of the remedy.

• The effectiveness of the remedy inreducing further releases.

• The ease of implementing the remedy.

• The degree to which local communi-ty concerns have been addressed.

Potential CorrectiveMeasures

Additional guidance on potential cor-rective measures is available from thefollowing documents:

• Corrective Action: Technologies andApplications (U.S. EPA, 1989c)

• Handbook: Stabilization Technologies forRCRA Corrective Actions (U.S. EPA,1991b)

• RCRA Corrective Action StabilizationTechnologies (U.S. EPA, 1992b)

• Pump-and-Treat Ground-WaterRemediation: A Guide for DecisionMakers and Practitioners (U.S. EPA,1996c)

• Handbook: Remediation ofContaminated Sediments (U.S. EPA,1991a)

• Abstracts of Remediation Case Studies(U.S. EPA, 1995)

• Bioremediation Resource Guide (U.S.EPA, 1993)

• Groundwater Treatment TechnologyResource Guide (U.S. EPA, 1994a)

• Physical/Chemical Treatment TechnologyResource Guide (U.S. EPA, 1994b)

• Soil Vapor Extraction TreatmentTechnology Resource Guide (U.S. EPA,1994d)

1. Meeting Cleanup StandardsWork with your state and community rep-

resentatives to establish risk-based cleanupstandards for the media of concern beforeidentifying potential corrective measures. Forexample, if there is a statistically significantincrease of constituent concentrations overbackground in the ground water, cleanupstandards would include reducing contami-nant concentrations to the MCL or health-based level at the point of monitoring.

Several approaches have been developed toidentify appropriate cleanup standards. One ofthe more recent approaches is the Risk-BasedCorrective Action (RBCA) standard developedby some states and the American Society forTesting and Materials (ASTM) Committee. TheRBCA standard provides guidance on how tointegrate ecological and human-health, risk-based, decision-making into the traditionalcorrective action process described above.RBCA is a decision-making process for theassessment and response to chemical releases.This standard is applicable to all types ofchemical-release sites, which can vary greatlyin terms of their complexity, physical andchemical characteristics, and the risk they poseto human health and the environment. RBCAuses a tiered approach that begins with simpleanalyses and moves to more complex evalua-tions when necessary. The foundation of theRBCA process is that technical policy decisionsare identified in the front-end of the process toensure that data collected are of sufficientquantity and quality to answer questionsposed at each tier of the investigation. TheRBCA standard is not intended to replaceexisting regulatory programs, but rather toprovide an enhancement to these programs.The RBCA process allows for a three-tieredapproach as described below.

In recent years, many states have adoptedsimilar risk-based guidance or rules. TheLouisiana Department of Environmental

Quality, for instance, promulgated its RiskEvaluation/Corrective Action Program(RECAP) final rule, on June 20, 2000.Likewise, the Texas Natural ResourceConservation Commission (TNRCC) finalizedthe Texas Risk Reduction Program in 1999(Title 30 Texas Administrative Code (TAC)Chapter 350). Your state and community rep-resentatives can tell you whether similar RBCAstandards exist in your state and the appropri-ateness of such an approach. ASTM also offerstwo training courses on RBCA: Risk-BasedCorrective Action for Chemical Releases, andRisk Based Corrective Action Applied atPetroleum Release Sites. These courses areopen to all individuals from federal, state, trib-al, and local regulatory agencies as well as pro-fessionals from the private sector.

RBCA Tier 1 Evaluation

A Tier 1 evaluation classifies a site accord-ing to the urgency for corrective action usingbroad measures of release and exposure. Thistier is used to identify the source(s) of thechemical release, obvious environmentalimpacts, potential receptors, and significantexposure pathways. During a Tier 1 evalua-tion, site-specific contaminant concentrationsare compared against a standard table of risk-based screening levels (RBSLs) that have beendeveloped using conservative, nonsite-specif-ic exposure assumptions. If a site’s contami-nant concentrations are found to be abovethe RBSLs, then corrective action or furtherevaluation would be considered. Continuedmonitoring might be the only requirement ifsite-specific contaminant concentrations arebelow the RBSLs.

At the end of the Tier 1 evaluation, initialcorrective action responses are selected whileadditional analysis is conducted to determinefinal remedial action, if necessary. The stan-dard includes an exposure scenario evalua-tion flowchart to help identify appropriate


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receptors and exposure scenarios based oncurrent and projected reasonable land usescenarios, and appropriate response actions.Site conditions should also be compared torelevant ecological screening criteria (RESC)applicable to the site which might includequalitative or quantitative benchmarks, com-parison of site conditions to local biologicaland environmental conditions, or considera-tions related to the exposed habitat areas.


The user might decide to conduct a Tier 2evaluation after selecting and implementingthe appropriate initial response action to theTier 1 evaluation. The purpose of this tier isto determine site-specific target levels (SSTLs)and appropriate points of compliance when itis determined that Tier 1 RBSLs have beenexceeded. While a Tier 2 evaluation is basedon similar screening levels as those used inthe Tier 1 evaluation, some of the genericassumptions used in the earlier evaluation arereplaced with site-specific measurements todevelop the SSTLs. The intent of Tier 2 is toincorporate the concept that measured levelsof contamination can decline over the dis-tance from source to receptor. Thus, simpleenvironmental fate and transport modeling isused to predict attenuation over that distance.If site-specific contaminant concentrations areabove the SSTLs, corrective action is neededand further analysis might be required.


A Tier 3 evaluation involves the same stepsas those taken during the Tier 1 and Tier 2evaluations, except that a significant increasein effort is employed to better define thescope of the contamination. Actual levels ofcontamination are compared to SSTLs thatare developed for this Tier. The Tier 3 SSTLsdiffer from Tier 2 SSTLs in the level ofsophistication used to develop site-specific

measures of the fate and transport of contam-inants. Where simplified, site-specific mea-sures of the fate and transport are used in theTier 2 evaluation, much more sophisticatedmodels and data will be used in this Tier.These models might rely on probabilisticapproaches and on alternative toxicity andbiodegradability data.

2. Evaluating TreatmentTechnologies

In nearly every phase of the correctiveaction process, some information about treat-ment technologies is important. Many docu-ments exist that describe candidatetechnologies in detail and give their respec-tive applicability and limitations. Below aredescriptions and examples of the three majortechnology categories: containment, extrac-tion, and treatment.

Containment technologies are used to stopthe further spread or migration of contami-nants. Some examples of common contain-ment techniques for constituents inland-based units include waste stabilization,solidification, and capping. Capping andother surface-water diversion techniques, forinstance, can control infiltration of rainwaterto the contaminated medium. Typical ways tocontain contaminated ground-water plumesinclude ground-water pumping, subsurfacedrains, and barrier or slurry walls. Theseground-water containment technologies con-trol the migration of contaminants in theground-water plume and prevent further dis-solution of contaminants by water enteringthe unit.

• Ground-water pumping. Ground-water pumping can be used tomanipulate and manage groundwater for the purpose of removing,diverting, and containing a contami-nated plume or for adjusting ground-

water levels to prevent plume move-ment. For example, pumping systemsconsisting of a series of extractionwells located directly downgradientfrom a contaminated source can beused to collect the contaminatedplume. The success of any contami-nant capture system based uponpumping wells is dependent uponthe rate of ground-water flow and therate at which the well is pumped.Thus, the zone of capture for thepumping system must be established.

• Subsurface drains. Subsurfacedrains are essentially permeable bar-riers designed to intercept theground-water flow. The water is col-lected at a low point and pumped ordrained by gravity to the treatmentsystem. Subsurface drains can also beused to isolate a waste disposal areaby intercepting the flow of unconta-minated ground water before it entersinto a contaminated site. Subsurfacedrains are most useful in preliminarycontainment applications for control-ling pollutant migration, while a finaltreatment design is developed andimplemented. They also provide ameasure of long-term protectionagainst residual contaminants follow-ing conclusion of treatment and siteclosure.

• Barrier walls. Low permeability bar-riers are used to direct the uncontam-inated ground-water flow around aparticular site or to prevent the cont-aminated material from migratingfrom the site. Barrier walls can bemade of a wide variety of materials,as long as they have a lower perme-ability than the aquifer. Typical mate-rials include mixtures of soil andbentonite, mixtures of cement and

bentonite, or barriers of engineeredmaterials (sheet piling). A chemicalanalysis of wall/contaminant compati-bility is necessary for the final selec-tion of materials. The installation of alow permeability barrier usuallyentails a great deal of earth moving,requires a significant amount of landarea, and is expensive. Once in place,however, it represents a long-term,low maintenance system.

Extraction or removal technologies physi-cally remove constituents from a site.Extraction techniques might remove the con-stituent of concern only, or the contaminatedmedia itself. For example, vapor extractionmight just remove the constituent vapors fromthe soil, while excavation could remove all ofthe contaminated soil. Extraction technologies

include excavation, pumping, product recov-ery, vapor extraction or recovery, and soilwashing.

Treatment or destruction technologies ren-der constituents less harmful through physi-cal, biological, chemical, and thermalprocesses including ground-water treatment,pH adjustment, oxidation and reduction,bioremediation, and incineration.

• Ground-water pump-and-treat isone of the most widely used ground-water treatment technologies.Conventional methods involve


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pumping contaminated water to thesurface for treatment. Pump-and-treat systems are used primarily forhydraulic containment and treatmentto reduce the dissolved contaminantconcentrations in ground water sothat the aquifer complies with clean-up standards or the treated waterwithdrawn from the aquifer can beput to beneficial use. A thorough,three-dimensional characterization ofsubsurface soils and hydrogeology,including particle-size distribution,sorption characteristics, andhydraulic conductivity, provides afirm basis for appropriate placementof pump-and-treat wells. The follow-ing techniques can be useful in effec-tively designing and operating thepump-and-treat system:

- Using capture zone analysis, opti-mization modeling, and dataobtained from monitoring theeffects of initial extraction wells toidentify the best locations for wells.

- Phasing the construction of extrac-tion and monitoring wells so thatinformation obtained from theoperation of the initial wellsinforms decisions about siting sub-sequent wells.

- Phasing pumping rates and theoperation of individual wells toenhance containment, avoid stagna-tion zones, and ensure removal ofthe most contaminated groundwater first.

• Chemical treatment is a class ofprocesses in which specific chemicalsare added to wastes or to contami-nated media in order to achievedetoxification. Depending on thenature of the contaminants, the

chemical processes required mightinclude pH adjustment, lysis, oxida-tion, reduction, or a combination ofthese. In addition, chemical treat-ment is often used to prepare for orfacilitate the treatment of wastes byother technologies.

- The function of pH adjustment is toneutralize acids and bases and topromote the formation of precipi-tates, which can subsequently beremoved by conventional settlingtechniques. Typically, pH adjust-ment is effective in treating inor-ganic or corrosive wastes.

- Oxidation and reduction reactionsare utilized to change the chemicalform of a hazardous material, inorder to render it less toxic or tochange its solubility, stability, sepa-rability, or otherwise change it forhandling or disposal purposes. Inany oxidation reaction, the oxida-tion state of one compound israised (i.e., oxidized) while the oxi-dation state of another compoundis lowered (i.e., reduced). In thereaction, the compound supplyingthe oxygen (or chlorine or othernegative ion) is called the oxidizeror oxidizing agent, while the com-pound accepting the oxygen (i.e.,supplying the positive ion) is calledthe reducing agent. The reactioncan be enhanced by catalysis, elec-trolysis, or photolysis.

- The basic function of lysis process-es is to split molecules to permitfurther treatment. Hydrolysis is achemical reaction in which waterreacts with another substance. Inthe reaction, the water molecule isionized while the other compound

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is split into ionic groups. Photolysis,another lysis process, breaks chemi-cal bonds by irradiating a chemicalwith ultraviolet light. Catalysis usesa catalyst to achieve bond cleavage.

• Biological treatment is a destructionprocess relying primarily on oxidativeor reductive mechanisms. The twotypes of biological treatment process-es are aerobic and anaerobic. Aerobicprocesses are oxidative processes andare the most widely used. Theseprocesses require a supply of molecu-lar oxygen and include suspendedgrowth systems, fixed-film systems,hybrid reactors, and in situ applica-tion. Anaerobic processes achieve thereduction of organic matter tomethane and carbon dioxide in anoxygen-free environment. The use ofbiological treatment processes isdirected toward accomplishingdestruction of organic contaminants,oxidation of organic chemicalswhereby the organic chemicals arebroken down into smaller con-stituents, and dehalogenation oforganic chemicals by cleaving a chlo-rine atom(s) or other halogens from acompound.

Biological processes can be used on abroad class of biodegradable organiccontaminants. It should be noted,however, that very high concentra-tions as well as very low concentra-tions of organic contaminants aredifficult to treat via biologicalprocesses. Since microorganisms needappropriate conditions in which tofunction, you must provide an opti-mum environment, whether above-ground in a reactor or belowgroundfor an in situ application. The prima-ry conditions which can affect the

growth of the microbial community,in addition to providing them suffi-cient food (organic material), are pH,temperature, oxygen concentration,nutrients, and toxicity.

- Typically, a biological treatment sys-tem operates best when a wastestream is at a pH near 7. However,waste treatment systems can operate(with some exceptions) between pHvalues of 4 and 10. The exceptionsare aerobic systems in whichammonia is oxidized to NOx as wellas anaerobic methane fermentingsystems. For these, the pH shouldbe between 6 and 8; outside thisrange, efficiency will suffer.

- Waste treatment systems can func-tion over a temperature range of 5°to 60°C. Most waste treatment sys-tems operate between 15° to 45°Cand use mesophilic organisms.

- Microorganisms need a certainamount of oxygen not only to sur-vive but also to control their reac-tions. Therefore, the residualdissolved oxygen concentrationsshould be maintained at approxi-mately 2 mg/l or greater within atypical liquid biotreatment system.

- The quantity of nutrients neededdepends on the biochemical oxygendemand (BOD) of the waste. Thehigher the BOD, the higher the num-ber of cells produced and the greaterthe quantity of nutrients required.

- The presence of toxic substanceswill obviously produce adverse con-ditions in a biological system.Unfortunately, it is difficult to citespecific toxic materials because toxi-city depends on concentration.Nutrients can be toxic in higher


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concentrations and all types oforganic compounds which can beused as food by bacteria can betoxic if their concentrations arehigh enough. Frequently, toxicityconcerns can be avoided by wastedilution and microbe acclimation.

• Thermal treatment, or incineration,is a treatment technology applicableto the treatment of wastes containinga wide range of organic concentra-tions and low concentrations ofwater, metals, and other inorganics.Incineration is the thermal decompo-sition of organic constituents viacracking and oxidation reactions athigh temperatures that can be usedfor detoxification, sterilization, vol-ume reduction, energy recovery, andby-product chemical recovery. Awell-designed and properly operatedincinerator will destroy all but a tinyfraction of the organic compoundscontained in the waste. Incineratoremission gases are composed primar-ily of carbon dioxide and water. Thetype and quantity of other com-pounds emitted depends on the com-position of the wastes, thecompleteness of the combustionprocess, and the air pollution controlequipment with which the incinera-tor is equipped. Incinerators aredesigned to accept wastes of varyingphysical forms, including gasses, liq-uids, sludges, and solids.

• Stabilization/solidification process-es immobilize toxic or hazardousconstituents in a waste by changingthe constituent into immobile forms,binding them in an immobile matrix,or binding them in a matrix whichminimizes the waste material surfaceexposed to solvent. Often, the immo-

bilized product has a structuralstrength sufficient to prevent fractur-ing over time. Solidification accom-plishes the intended objective bychanging a non-solid waste materialinto a solid, monolithic structure thatideally will not permit liquids to per-colate into or leach materials out ofthe mass. Stabilization, on the otherhand, binds the hazardous con-stituents into an insoluble matrix orchanges the hazardous constituent toan insoluble form. Other objectivesof solidification/stabilization process-es are to improve handling of thewaste and produce a stable solid (nofree liquid) for subsequent use as aconstruction material or for landfill-ing. Major categories of industrialwaste solidification/stabilization sys-tems are cement-based processes.Waste characteristics such as organiccontent, inorganic content, viscosity,and particle size distribution canaffect the quality of the final solidi-fied product. These characteristicsinhibit the solidification process byaffecting the compatibility of thebinder and the waste, the complete-ness of encapsulation, and the devel-opment of preferential paths forleaching due to spurious debris inthe waste matrix.

In selecting a treatment technology or setof technologies, it is important to consider theinformation obtained from the waste and sitecharacterizations, see Chapter2–Characterizing Waste and Chapter4–Considering the Site. For example, thewaste characterization should tell the locationof the waste and in what phase(s) the wasteshould be expected to be found, (e.g., sorbedto soil particles). Waste characterization infor-mation also allows for the assessment of theleaching characteristics of the waste, its ability

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1 U.S. EPA, 1991. Site Characterization for Subsurface Remediations.


to be degraded, and its tendency to react withchemicals. The site characterization informa-tion should reveal important informationabout subsurface flow conditions and otherphysical characteristics, such as organic car-bon content. You should use the informationfrom the waste and site characterizations toselect the appropriate treatment technology.

A screening process for selecting an appro-priate technology is presented in Figure 2. Insome cases, a treatment train, a series of tech-nologies combined together, might be appro-priate.1 This step-by-step approach helpsensure that technologies that might be applic-able at a site are not overlooked. In addition,the rationale for the elimination of specifictechnologies will be available to justify deci-sions to interested parties.

Additional information regarding the useand development of innovative treatmenttechnologies is available from EPA’sHazardous Waste Clean-up Information(CLU-IN) Web site <clu-in.org>. This Website describes programs, organizations, publi-cations, and other tools for all waste remedia-tion stakeholders. Of particular interest is theRemediation Technologies Screening Matrixwhich is a user-friendly tool to screen fortechnologies for a remediation project. Thematrix allows you to screen through 64 insitu and ex situ technologies for either soil orground-water remediation. Variables used inscreening include contaminants, developmentstatus, overall cost, and cleanup time. Thematrix can be accessed through CLU-IN ordirectly from the Federal RemediationTechnologies Roundtable’s Web site<www.frtr.gov/matrix2/top_page.html>.

Another source of information is the FieldAnalytic Technologies Encyclopedia (FATE)developed by EPA’s Technology InnovationOffice (TIO), in collaboration with the U.S.Army Corps of Engineers. FATE is an onlineencyclopedia of information about technolo-

gies that can be used in the field to character-ize contaminated soil and ground water,monitor the progress of remedial efforts, andin some cases, confirm sampling and analysisfor site closure. To access FATE visit:<www.epa.gov/tio/chartext_tech.htm>.


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Figure 2

Recommended Screening Process forSelecting Appropriate Treatment Technologies

Evaluate waste and site-specific information andidentify potential treatment technologies

Develop a conceptual design for each technolo-gy including:• Process description• Process flow diagram• Layout drawing • Preliminary sizing of equipment, utility, and

land requirements• Chemical requirements• Expected residuals

Compare technologies using:• Effectiveness and reliability of technology

meeting cleanup goals• Beneficial and adverse effects on the environ-

ment• Beneficial and adverse effects on human

health• Ability to meet federal, state, and local govern-

ment standards and gain public acceptance• Capital, operating, and maintenance costs

Select most appropriate technology in consulta-tion with state and community representatives

Obtain state approval

3. Evaluating the Long- andShort-Term Effectiveness ofthe Remedy

Evaluating the long- and short-term effec-tiveness of the remedy, involves analyzing therisks associated with potential exposure path-ways, estimates of potential exposure levels,and the duration of potential exposure asso-ciated with the construction and implemen-

tation of the corrective measure. Becausewaste characteristics vary from site to site,the effect of a treatment technology with aparticular waste might be unknown. It isimportant, therefore, to consider performinga treatability study to evaluate the effective-ness of one or more potential remedies.Spending the time and money up-front tobetter assess the effectiveness of a technologyon a waste can save significant time andmoney later in the process. To judge thetechnical certainty that the remedy will attainthe corrective action goal, also considerreviewing case studies where similar tech-nologies have been applied.

It is also important to analyze the time tocomplete the corrective measure, because itdirectly impacts the cost of the remedy. It istherefore important to carefully evaluate thelong-term costs of the remedial alternativesand the long-term financial condition of thefacility. Consider including quality controlmeasures in the implementation schedule toassess the progress of the corrective measure.It is also important to determine the degreeto which the remedy complies with allapplicable state laws.

The Federal Remediation TechnologiesRoundtable <www.frtr.gov> is at the fore-front of the federal government’s efforts topromote interagency cooperation to advancethe use of innovative remediation technolo-gies. Roundtable member agencies includeEPA, the U.S. Department of Defense, theU.S. Department of Energy, and the U.S.Department of Interior. This group has pre-pared over 209 cost and performance reportsthat can be accessed through CLU-IN <clu-in.org/remed1.cfm>. These reportscontained in the “Federal RemediationTechnologies Roundtable Case Studies” docu-ment results from completed full-scale haz-ardous waste site remediation projects andseveral large-scale demonstration projects.

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Treatability StudiesThe four general types of treatability

studies are laboratory-scale, bench-scale,pilot-scale, and field-scale.

• Laboratory-scale studies are smallscale screening studies that generatequalitative information concerningthe general validity of a treatmentapproach.

• Bench-scale studies are intermediatestudies conducted in the laboratory.Bench scale studies are intended toanswer specific design, operation, andcost questions, and are more detailedthan laboratory studies.

• Pilot-scale studies are large scaleexperiments intended to providequantitative cost and design data.They simulate anticipated full-scaleoperational configurations as closelyas possible.

• Field-scale studies are large scalestudies intended to monitor the per-formance of treatment systems underreal world conditions at close to fullscale operations.

More information on treatability stud-ies can be found in A Guide forConducting Treatability Studies UnderCERCLA (U.S. EPA, 1992a).

They are meant to serve as primary referencesources, and they contain information on sitebackground and setting, contaminants andmedia treated, technology, cost and perfor-mance, and points of contact for the technol-ogy application.

EPA has also prepared an overview ofground-water cleanup at 28 sites entitledGroundwater Cleanup: Overview of OperatingExperience at 28 Sites (U.S. EPA, 1999a) that isalso available from CLU-IN. This overviewpresents a range of the types of cleanups typi-cally performed at sites with contaminatedground water and summarizes informationabout the remediation systems at the 28 sites.Summarized information includes design,operation, and performance of the systems;capital, operating, and unit costs of the sys-tems; and factors that potentially affect the costand performance of the systems.

EPA’s TIO Web site <www.epa.gov/tio>provides additional information about sitecharacterization and treatment technologiesfor remediation. This Web site offers technol-ogy selection tools and describes programs,organizations, and available publications.Some of the available publications includeAbstracts of Remediation Case Studies, Volumes1-4 (U.S. EPA, 2000a) which summarize 218case studies of site remediation prepared byfederal agencies. Many of these publicationsand links are also available through CLU-IN.

4. Evaluating the Effectiveness ofReducing or Eliminating theSource of Contamination

There are two major components of sourcecontrol that should be evaluated. First, ifsource control consists of the removal, redis-posal, or treatment of wastes, the volume ofwastes and residual materials should bequantified and the potential to cause furthercontamination evaluated. Second, engineeringcontrols intended to upgrade or repair defi-

cient conditions at a waste management unitshould be quantified in terms of anticipatedeffectiveness according to current and futureconditions. This evaluation should determinewhat is technically and financially practicable.Health considerations and the potential forunacceptable exposure(s) to both workersand the public can affect an evaluation.

5. Evaluating the Ease ofImplementation

The ease of implementing the proposedcorrective measure will affect its schedule. Toevaluate the ease of implementation of a spe-cific corrective measure, it is important to


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Selecting a CorrectiveAction Specialist

Once it has been determined that cor-rective measures are necessary, you shoulddetermine if in-house expertise is adequateor if an outside consultant is necessary.

If a consultant is needed, determine ifthe prospective consultant has the tech-nical competence to do the work need-ed. A poor design for a recovery system,unacceptable field procedures, lack offamiliarity with state requirements, or aninadequate investigation might unneces-sarily cost thousands of dollars and stillnot complete the cleanup.

Some of the most important informa-tion to consider in selecting a consultantis whether the consultant has experienceperforming site investigations and reme-diations at similar sites, is familiar withstate regulations, has staff trained in theuse of field screening instruments, hasexperience in monitoring well designand installations, has established qualityassurance and quality control proce-dures, and can provide references.

consider the availability of technical expertiseand equipment, the ability to properly man-age, dispose, or treat wastes generated by thecorrective measure, and the likelihood ofobtaining local permits and public accep-tance for the remedy. Consider also thepotential for contamination to transfer fromone media to another as part of the overallfeasibility of the remedy. Cross-mediaimpacts should be addressed as part of theimplementation phase. Develop a corrective-measure schedule identifying the beginningand end periods of the permitting, construc-tion, treatment, and source control measures.

6. Measuring the Degree toWhich Community Concernsare Met

Prior to selecting the corrective measure(s),you should hold a public meeting to discussthe results of the corrective action assessmentand to identify proposed remedies. Considernotifying adjacent property owners via mail of

any identified contamination and proposedremedies. You also should identify any publicconcerns that have been expressed, via writ-ten public comments or from public meet-ings, about the facility’s contamination andshould address these concerns by the correc-tive measures being evaluated. The best reme-dy selected and implemented will be the onethat is agreed upon by the state or local regu-latory agency, the public, and the facilityowner. Review Chapter 1–Understanding Riskand Building Partnerships before selecting anyfinal remedies.

E. ImplementingCorrective Measures

The implementation of corrective mea-sures encompasses all activities necessary toinitiate and continue remediation. During theevaluation and assessment of the nature andextent of the contamination, you shoulddecide whether no further assessment is nec-essary, whether institutional controls are nec-essary to protect human health and theenvironment, whether monitoring and sitemaintenance are necessary, and whether nofurther action and closure are appropriate forthe unit.

1. Institutional ControlsInstitutional controls are those controls

that can be utilized by responsible partiesand regulatory agencies in remedial programswhere, as part of the program, certain levelsof contamination will remain on site in thesoil or ground water. Institutional controlscan also be considered in situations wherethere is an immediate threat to humanhealth. Institutional controls can vary in bothform and content. Agencies and landownerscan invoke various authorities and enforce-ment mechanisms, both public and private,to implement one or more of the controls. A

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Citizen Guides toTreatment Technologies

EPA’s Technology Innovation Officehas developed a series of fact sheets thatexplain, in basic terms, the operationand application of innovative treatmenttechnologies for remediating sites. Thefact sheets address issues associated withinnovative treatment technologies as awhole, bioremediation, chemical dehalo-genation, in situ soil flushing, naturalattenuation, phytoremediation, soilvapor extraction and air sparging, soilwashing, solvent extraction, thermal des-orption, and the use of treatment walls.English and Spanish versions of thesefact sheets can be downloaded fromCLU-IN <clu-in.org/remed1.cfm>.

state could adopt a statutory mandate, forexample, requiring the use of deed restric-tions as a way of enforcing use restrictionsand posting signs. Commonly used institu-tional controls include deed restrictions, userestrictions, access controls, notices, registryact requirements, transfer act requirements,and contractual obligations. Additional infor-mation on institutional controls is available atEPA’s Office of Solid Waste and EmergencyResponse Web site at <www.epa.gov/oerrpage/superfund/action/postconstruction/ic.htm>.

• Deed restrictions. These restrictions,also called restrictive covenants, placelimits on the use and conveyance ofland. They inform prospectiveowners/tenants of the environmentalstatus of the property and ensure long-term compliance with the institutionalcontrols. Typically, there are fourrequirements for a promise in a deedrestriction: the conveyance of land mustbe documented in writing; it shouldprecisely reflect the parties’ intentionswith respect to the scope and durationof the restrictions; there should be“privity of estate” so that it can beenforced by states; and the promise“touches and concerns the land.”

• Use restrictions. Use restrictions areusually the heart of what is in a deedrestriction. Use restrictions describeappropriate and inappropriate uses ofthe property, in an effort to perpetu-ate the benefits of the remedial actionand ensure property use that is con-sistent with the applicable cleanupstandard. Such techniques also pro-hibit any person from making use ofthe site in a manner that creates anunacceptable risk of human or envi-ronmental exposure to the residualcontamination. Use restrictions

address uses that might disturb acontainment cap or any unremediat-ed soils under the surface or below abuilding. A prohibition on drinkingonsite or offsite ground water mightalso be appropriate. Well restrictionareas can be a form of institutionalcontrol by providing notice of theexistence of contaminants in groundwater and by prohibiting or condi-tioning the placement and use of anyor all wells within an area.

• Access controls. Access to any par-ticular site can be controlled by eitherfencing and gates, security, or postingor warnings. A state might use thefollowing criteria to determine theappropriate level and means of accesscontrol: whether the site is located ina residential or mixed-use neighbor-hood; proximity to sensitive land-useareas including day care centers,playgrounds, and schools; andwhether the site is frequently tra-versed by neighbors.

• Notices. Controls of this type gener-ally provide notice of specific locationof contamination on site and discloseany restrictions on access, use, anddevelopment of part or all of the con-taminated site to preserve the integri-ty of the remedial action. Types ofnotices include record notice (noticeson land records), actual notice (directnotice of environmental informationto other parties to a land transaction),and notice to government authorities.

• Registry act requirements. Somestates have registry act programs thatprovide for the maintenance of a reg-istry of hazardous waste disposal sitesand the restriction of the use andtransfer of listed sites. When a siteappears on the registry, the owner


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must comply with regulatory require-ments in regard to use and transfer ofthe site. The use of a site listed onthe registry can not be changed with-out permission from the state agency.

• Transfer act requirements. Somestates have transfer act programs thatrequire full evaluation of all environ-mental issues before or after thetransfer occurs. It might be that,within such a program, institutionalcontrols can be established by way ofconsent order, administrative order,or some other technique that estab-lishes implementation and continuedresponsibility for institutional con-trols. A typical transfer act imposesobligations and confers rights on par-ties to a land transaction arising outof the environmental status of theproperty to be conveyed. Transferacts impose information obligationson the seller or lessor of a property.That party must disclose generalinformation about strict liability forclean-up costs as well as property-specific information, such as thepresence of hazardous substances,permitting requirements and status,releases, and enforcement actionsand variances.

• Contractual obligations. One sys-tem for ensuring future restrictionson the use of a site, or the obligationto remediate a site, is to require pri-vate parties to restrict use by con-tract. While this method is oftennegotiated among private parties, it isdifficult, if not impossible, to institu-tionalize control over the processwithout interfering with the abilities

and rights of private parties to freelynegotiate these liabilities. Anotheravenue is for the landowner orresponsible party to obligate itself tothe state by contract. The state mightrequire a contractual commitmentfrom the party to provide long-termmonitoring of the site, use restric-tions, and the means of continuedfunding for remediation.

2. Monitoring and SiteMaintenance

In many cases, monitoring might need tobe conducted to demonstrate the effective-ness of the implemented corrective measures.Consult with your state to determine theamount of time that monitoring should beconducted. Some corrective measures, suchas capping, hydraulic control, and otherphysical barriers, can require long-termmaintenance to ensure integrity and contin-ued performance. Upon completion and veri-fication of cleanup goals, reinstitute youroriginal or modified ground-water monitor-ing program if the unit is still in active use.

3. No Further Action and SiteClosure

When the corrective action goals havebeen achieved, and monitoring and sitemaintenance are no longer necessary toensure that this condition persists, reinstituteyour original or modified ground-water mon-itoring program if the unit is still in activeuse. It might be necessary, however, to ensurethat any selected institutional controls remainin place. Refer to Chapter 11–PerformingClosure and Post-Closure Care for additionalinformation on site closures.

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10-23

Consider the following when developing a corrective action program for industrial waste managementunits:

■■■■ Locate the source(s) of the release(s) of contaminants and determine the extent of the contamina-tion.

■■■■ Consult with the state, community representatives, and qualified remedial experts when develop-ing a corrective action program.

■■■■ Identify and evaluate all potential corrective measures including interim measures.

■■■■ Select and implement corrective measures based on the effectiveness and protectiveness of theremedy, the ease of implementing the remedy, and the degree that the remedy meets local commu-nity concerns and all applicable state laws.

■■■■ Design a program to monitor the maintenance and performance of corrective measures to ensurethat human health and the environment are being protected.

Taking Corrective Action Activity List

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ASTM. 1997. Standard Provisional Guide for Risk-Based Corrective Action (PS104). February.

ASTM. 1994. Emergency Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites.May.

Louisiana Department of Environmental Quality. 2000. Risk Evaluation/Corrective Action Program (RECAP)June.

Texas Natural Resource Conservation Commission (TNRCC). 1999. Texas Risk Reduction Program, Title 30Texas Administrative Code (TAC) Chapter 350.

Texas Natural Resource Conservation Commission (TNRCC). 1995. TNRCC Technical Guidance: Selecting anEnvironmental Consultant/Corrective Action Specialist. February.

U.S. EPA. 2002. Draft Superfund Lead-Contaminated Residential Sites Handbook. OSWER 9285.7-50.

U.S. EPA. 2001a. Development of a Data Evaluation: Decision Support System for Remediation of SubsurfaceContamination. EPA600-R-01-044.

U.S. EPA. 2001b. Development of Recommendations and Methods to Support Assessment of Soil VentingPerformance and Closure. EPA600-R-01-070.

U.S. EPA. 2001c. Evaluation of the Protocol for Natural Attenuation of Chlorinated Solvents: Case Study atthe Twin Cities Army Ammunition Plant. EPA600-R-01-025.

U.S. EPA. 2001d.Handbook of Groundwater Protection and Cleanup Policies for RCRA Corrective Action.EPA530-R-01-015.

U.S. EPA. 2001e. Multispecies Reactive Tracer Test in a Sand and Gravel Aquifer, Cape Cod, Massachusetts.Parts I-II. EPA600-R-01-007a-b.

U.S. EPA. 2001f. Summary of the Phytoremediation State of the Science Conference, Boston Massachusetts,May 1-2, 2000. EPA625-R-01-001a.

U.S. EPA. 2000a. Abstracts of Remediation Case Studies. Volume 4. EPA542-R-00-006.

U.S. EPA. 2000b. Statistical Estimation and Visualization of Ground-Water Contamination Data. EPA600-R-00-034.

Resources


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U.S. EPA. 1999a. Groundwater Cleanup: Overview of Operating Experience at 28 Sites. EPA542-R-99-006.

U.S. EPA. 1999b. In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium andTrichloroethylene in Ground Water: Volume 1 Design and Installation. EPA600-R-99-095a.

U.S. EPA. 1999c. In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium andTrichloroethylene in Ground Water: Volume 2 Performance Monitoring. EPA600-R-99-095b.

U.S. EPA. 1999d. In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium andTrichloroethylene in Ground Water: Volume 3 Multicomponent Reactive Transport Modeling. EPA600-R-99-095c.

U.S. EPA. 1999e. Laser Fluorescence EEM Probe for Cone Penetrometer Pollution Analysis. EPA600-R-99-041.

U.S. EPA. 1998a. Application of the Electromagnetic Borehole Flowmeter. EPA600-R-98-058.

U.S. EPA. 1998b. Permeable Reactive Barrier Technologies for Contaminant Remediation. EPA600-R-98-125.

U.S. EPA. 1998c. Technical Protocol for Evaluating natural Attenuation of Chlorinated Solvents in GroundWater, EPA600-R-98-128.

U.S. EPA. 1996a. A Citizen’s Guide to Innovative Treatment Technologies. EPA542-F-96-001.

U.S. EPA. 1996b. Corrective Action for Releases from Solid Waste Management Units at Hazardous WasteManagement Facilities: Advance Notice of Proposed Rulemaking. Fed. Reg. 61(85): 19,431- 19,464. May 1.

U.S. EPA. 1996c. Pump-and-Treat Ground-Water Remediation: A Guide for Decision-Makers andPractitioners. EPA625-R-95-005.

U.S. EPA. 1995. Abstracts of Remediation Case Studies. EPA542-R-95-001.

U.S. EPA. 1994a. Groundwater Treatment Technology Resource Guide. EPA542-B-94-009.

U.S. EPA. 1994b. Physical/chemical Treatment Technology Resource Guide. EPA542-B-94-008.

Resources (cont.)

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Resources (cont.)U.S. EPA. 1994c. RCRA Corrective Action Plan. EPA520-R-94-004.

U.S. EPA. 1994d. Soil Vapor Extraction Treatment Technology Resource Guide. EPA542-B-94-007.

U.S. EPA. 1993. Bioremediation Resource Guide. EPA542-B-93-004.

U.S. EPA. 1992a. A Guide for Conducting Treatability Studies under CERCLA. EPA540-R-92-071.

U.S. EPA. 1992b. RCRA Corrective Action Stabilization Technologies Proceedings. EPA625-R-92-014.

U.S. EPA. 1991a. Handbook: Remediation of Contaminated Sediments. EPA625-6-91-028.

U.S. EPA. 1991b. Handbook: Stabilization Technologies for RCRA Corrective Action. EPA625-6-91- 026.

U.S. EPA. 1991c. Site Characterization for Subsurface Remediation. EPA625-4-91-026.

U.S. EPA. 1989a. RCRA Facility Investigation Guidance: Volume I: Development of an RFI Work Plan andGeneral Considerations for RCRA Facility Investigations. PB89-200-299.

U.S. EPA. 1989b. RCRA Facility Investigation Guidance: Volume II: Soil, Ground Water, and Subsurface GasReleases. PB89-200-299.

U.S. EPA. 1989c. RCRA Facility Investigation Guidance: Volume III: Air and Surface Water Releases. PB89-200-299.

U.S. EPA. 1989d. RCRA Facility Investigation Guidance: Volume IV: Case Study Examples. PB89-200-299.

U.S. EPA. 1989e. Seminar Publication: Corrective Action: Technologies and Applications. EPA625-4-89-020.

U.S. EPA. 1989f. Practical Guide for Assessing and Remediating Contaminated Sites: Draft.

U.S. EPA. 1988a. Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA.Interim Final. EPA540-G-89-004.

U.S. EPA. 1988b. RCRA Corrective Action Interim Measures Guidance - Interim Final. EPA530-SW-88-029.

U.S. EPA. 1986. RCRA Facility Assessment Guidance. PB87-107769.


Chapter 11Performing Closure and Post-Closure Care

Contents

I. Closure Plans ........................................................................................................................................11- 1

II. Selecting a Closure Method....................................................................................................................11- 3

III. Closure by Use of Final Cover Systems..................................................................................................11- 4

A. Purpose and Goal of Final Cover Systems ............................................................................................11- 4

B. Technical Considerations for Selecting Cover Materials ........................................................................11- 5

C. Components of a Final Cover ..............................................................................................................11- 8

D. Capillary-Break Final Covers ............................................................................................................11- 16

E. The Hydrologic Evaluation of Landfill Performance (HELP) Model ....................................................11- 17

F. Recommended Cover Systems ............................................................................................................11- 18

IV. Closure by Waste Removal ..................................................................................................................11- 21

A. Establishing Baseline Conditions ........................................................................................................11- 22

B. Removal Procedures............................................................................................................................11- 22

C. Disposal of Removed Wastes ..............................................................................................................11- 23

D. Final Sampling and Analysis ..............................................................................................................11- 23

V. Post-Closure Care Considerations When Final Cover Is Used..............................................................11- 24

A. Maintenance........................................................................................................................................11- 24

B. Monitoring During Post-Closure Care ................................................................................................11- 25

C. Recommended Length of the Post-Closure Care Period ......................................................................11- 25

D. Closure and Post-Closure Cost Considerations ..................................................................................11- 26

Performing Closure and Post-Closure Care Activity List ............................................................................11- 34

Resources ..................................................................................................................................................11- 35

Tables:

Table 1: Types of Layers in Final Cover Systems........................................................................................11- 9

Table 2: Types of Recommended Final Cover Systems ............................................................................11- 18

Table 3: Example Closure/Post-Closure Cost Estimate Form ..................................................................11- 27

Table 4: Sample Summary Cost Estimating Worksheet ..........................................................................11- 29

Table 5: Estimated Closure and Post-Closure Care Costs ........................................................................11- 31

Figures:

Figure 1: Regional Depth of Frost Penetration in Inches ..........................................................................11 - 6

Figure 2: Drainage Layer Configuration ................................................................................................11 - 11

Contents (cont.)

Figure 3: Geonet with Geotextile Filter Design for Drainage Layer ........................................................11 - 12

Figure 4: Passive Gas Venting System ....................................................................................................11 - 15

Figure 5: Active Gas Venting System......................................................................................................11 - 15

Figure 6: Example of a Capillary-Break Final Cover System ..................................................................11 - 17

Figure 7: Recommended Final Cover System For a Unit With a Double Liner or a Composite Liner ....11 - 19

Figure 8: Recommended Final Cover System For a Unit With a Single Clay Liner ................................11 - 19

Figure 9: Recommended Final Cover System For a Unit With a Single Clay Liner in an Arid Area ......11 - 20

Figure 10: Recommended Final Cover System For a Unit With a Single Synthetic Liner ......................11 - 20

Figure 11: Recommended Final Cover System For a Unit With a Natural Soil Liner ............................11 - 21

Ensuring Long-Term Protection—Performing Closure and Post-Closure Care

11-1

The overall goal of closure is tominimize or eliminate potentialthreats to human health and theenvironment and the need forfuture corrective action at the site.

If removing the wastes, containment devices,and any contaminated subsoils from a unit,the unit should be returned to an acceptablerisk level so that it is not a current or futurethreat. If wastes will be left in place at clo-sure, the unit should be closed in a mannerthat also reduces and controls current orfuture threats. Steps should also be taken toavoid future disruptions to final cover sys-tems and monitoring devices.

For post-closure care, the overall goal is tominimize the infiltration of water into a unitby providing maintenance of the final cover.Maintenance should be continued until suchtime as it is determined that care is no longernecessary. Also, during post-closure care,closed units should be monitored to verifyand document that no unacceptable releasesare occurring.

I. Closure PlansA well-conceived closure plan is the pri-

mary resource document for the final stage inthe life of a waste management unit. The pur-pose of a closure plan is to consider allaspects of the closure scenario. It should becomprehensive so that staff who will imple-ment it years after its writing will clearlyunderstand the activities it specifies. It alsoneeds to provide enough detail to allow cal-culation of closure and post-closure care costsfor determining how much funding needs tobe set aside for those activities.

Performing Closure and Post-Closure CareThis chapter will help you:

• Provide closure and post-closure care as an integral part of a

unit’s overall design and operation.

• Provide long-term environmental protection by reducing or elimi-

nating potential threats and the need for potential corrective

action at the site.

• Plan and accomplish the goals of closure and post-closure care by

requiring that adequate funding be set aside to cover the

planned costs of closure and post-closure care.

This chapter will help address the follow-ing questions.

• How do I develop a closure plan?

• What factors should I consider whenchoosing a closure method?

• What are the components of a finalcover?

• What costs are associated with post-closure care?

11-2


What should be considered when

developing a closure plan?

You should tailor a closure plan to accountfor the unique characteristics of the unit, thewaste managed in the unit, and anticipatedfuture land use. Each unit will have differentclosure activities. Closing a surface impound-ment, for example, involves removal ofremaining liquids and solidifying sludgesprior to placing a final cover on the unit.

The following information is important toconsider when developing a closure plan:

• Overall goals and objectives of closure.

• Future land use.

• Type of waste management unit.

• Types, amount, and physical state ofwaste in the unit.

• Constituents associated with the wastes.

• Whether wastes will be removed orleft in place at closure.

• Schedule (overall and interim).

• Costs to implement closure.

• Steps to monitor progress of closureactions, including inspections, mainte-nance, and monitoring (e.g., ground-water and leachate monitoring).

• Health and safety plans, as necessary.

• Contingency plans.

• Description of waste treatment or sta-bilization (if applicable).

• Final cover information (if applicable).

• Vegetation management.

• Run-on and runoff controls.

• Closure operations and maintenance.

• Erosion prevention and repair.

• Waste removal information (if applica-ble).

• Parameters to assess performance ofthe unit throughout the post-closureperiod.

The plan should address the types of wastethat have been or are expected to be depositedin the management unit and the constituentsthat can reasonably be associated with thosewastes. The types of expected wastes willaffect both the design of the final cover andthe types of activities that should be undertak-en during the post-closure care period.Biodegradable waste, for example, can cause afinal cover to subside due to decompositionand can also require gas management.

The closure plan should provide otherinformation that will address the closure strat-egy. If, for instance, a final cover is planned,then the closure plan should consider season-al precipitation that could influence the per-formance of both the cover and themonitoring system. Information concerningfreeze cycles and the depth of frost perme-ation will provide supporting informationwith which to assess the adequacy of thecover design. Similarly, arid conditions shouldbe addressed to support a decision to use aparticular cover material, such as cobbles.

The closure plan should address the closureschedule, stating when closure is expected tobegin, and when closure is expected to be com-pleted. You should consider starting closurewhen the unit has reached capacity or hasreceived the last expected waste for disposal.For units containing inorganic wastes, youshould complete closure as soon as possibleafter the last expected waste has been received.A period of 180 days is a good general guidefor completing closure, but the actual timeframe will be dictated by site-specific condi-tions. For units receiving organic wastes, moretime might be needed for the wastes to stabilize


11-3

prior to completing closure. Similarly, othersite-specific conditions, such as precipitationor winter weather, can also cause delay incompleting closure. For these situations, youshould complete closure as soon as feasible.You should also consult with the state agencyto determine if any requirements exist for clo-sure schedules.

Even within a waste management unit,some areas will be closed on different sched-ules, with certain areas in partial closure,while other areas continue to operate. Theschedules and partial closure activities (suchas intermediate cover) should be consideredin the closure plan. Although the processesfor closing such areas might not be differentthan those for closing the unit as a whole, itis still more efficient to integrate partial clo-sure activities into the closure plan.

If the closure plan calls for the stabiliza-tion, solidification, or other treatment ofwastes in the unit before the installation of afinal cover, the plan should describe thoseactivities in detail. Waste stabilization, solidi-fication, or other treatment has four goals:

• Removing liquids, which are ill-suit-ed to supporting the final cover.

• Decreasing the surface area overwhich the transfer or escape of conta-minants can occur.

• Limiting the solubility of leachableconstituents in the waste.

• Reducing toxicity of the waste.

For closure strategies that will use engi-neering controls, such as final covers, the planshould provide detailed specifications. Thisincludes descriptions of the cover materials ineach layer and their permeability as well asany drainage and/or gas migration controlmeasures included in the operation of thefinal cover. Also the plan should identify mea-sures to verify the continued integrity of the

final cover and the proper operation of the gasmigration and/or drainage control strategies.

If wastes will be removed at closure, the clo-sure plan should estimate volumes of waste andcontaminated subsoil and the extent of contam-inated devices to be removed during closure. Itshould further state waste removal procedures,establish performance goals, and address anystate or local requirements for closure by wasteremoval. The plan should identify numericclean-up standards and existing backgroundconcentrations of constituents. It also shoulddiscuss the sampling plan for determining theeffectiveness of closure activities. Finally, itshould describe the provisions made for the dis-posal of removed wastes and other materials.

The closure plan should also provide adetailed description of the monitoring thatwill be conducted to assess the unit’s perfor-mance throughout the post-closure period.These measurements include monitoringleachate volume and characteristics to ensurethat a cover is minimizing infiltration. It isimportant to include appropriate ground-water quality standards with which to com-pare ground-water monitoring reports. Youshould develop the performance measuressection of the plan prior to completing clo-sure. This section establishes the parametersthat will describe successful closure of theunit. If limits on these parameters are exceed-ed, it will provide an early warning that thefinal cover system is not functioning asdesigned and that measures should be under-taken to identify and correct problems.

II. Selecting aClosure Method

Factors to consider in deciding whether toperform closure by means of waste removalor through the use of a final cover include thefollowing:

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• Feasibility. Is closure by wasteremoval feasible? For example, if thewaste volumes are large and underlyingsoil and ground water are contaminat-ed, closure by total waste removalmight not be possible. If the unit iscontaminated, consult Chapter10–Taking Corrective Action to identifyactivities to address the contamination.In some cases partial removal of thewaste might be useful to remove thesource of ground-water contamination.

• Cost-effectiveness. Compare the costof removing waste, containmentdevices, and contaminated soils, plussubsequent disposal costs at anotherfacility, to the cost of installing a finalcover and providing post-closure care.

• Long-term protection. Will the finalcover control, minimize, or eliminatepost-closure escape of waste con-stituents or contaminated runoff toground or surface waters to the extentnecessary to protect human health andthe environment?

• Availability of alternate site. Is analternate site available for final dispos-al or treatment of removed waste? Youshould consult with the state agencyto determine whether alternate dispos-al sites are appropriate.

Sections III and V address closure by use offinal cover systems and associated post-closurecare considerations. Alternatively, Section IVaddresses closure by waste removal.

III. Closure by Useof Final CoverSystems

You might elect to close a waste manage-ment unit by means of a final cover system.

This approach is common for landfill units andsome surface impoundment units where somewaste is left in place. The choice of final covermaterials and design should be the result of acareful review and consideration of all site-spe-cific conditions that will affect the performanceof the cover system. If you are not knowledge-able about the engineering properties of covermaterials, you should seek the advice of profes-sionals or representatives of state and localenvironmental protection agencies.

This section addresses the more importanttechnical issues that should be consideredwhen selecting cover materials and designing acover system. It discusses the various potentialcomponents of final cover systems, includingthe types of materials that can be used in theirdesign and some of the advantages and disad-vantages of each. This section also examinesthe interaction between the various compo-nents as they function within the system.

A. Purpose and Goal ofFinal Cover Systems

The principal goals of final cover systemsare to:

• Provide long-term environmental pro-tection of human health and the envi-ronment by reducing or eliminatingpotential risk of contaminant release.

• Minimize infiltration of precipitationinto the waste management unit tominimize generation of leachates with-in the unit by promoting surfacedrainage and maximizing runoff.

• Minimize risk by controlling gas migra-tion (as applicable), and by providingphysical separation between waste andhumans, plants, and animals.

• Minimize long-term maintenance needs.

The final cover should be designed to pro-vide long-term protection and minimization of


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leachate formation. Final cover systems canbe inspected, managed, and repaired to main-tain long-term protection. For optimal perfor-mance, the final cover system should bedesigned to minimize infiltration, surfaceponding, and the erosion of cover material.To avoid the accumulation of leachate withina unit, the cover system should be no morepermeable than the liner system. For exam-ple, if a unit’s bottom liner system is com-posed of a low-permeability material, such ascompacted clay or a geomembrane, then thecover should also be composed of a low-per-meability material unless an evaluation ofsite-specific conditions shows an equivalentreduction in infiltration. If the cover system ismore permeable than the liner, leachate willaccumulate in the unit. This buildup of liq-uids within a unit is often referred to as the“bathtub effect.” In addition, since manyunits can potentially generate gas, cover sys-tems should be designed to control gasmigration. Proper quality assurance and qual-ity control during construction and installa-tion of the final cover are essential in order toensure that the final cover performs in accor-dance with its design. For general informa-tion on quality assurance during constructionof the final cover, refer back to the construc-tion quality assurance section of Chapter 7,Section B–Designing and Installing Liners.Recommendations for the type of final coversystem to use will depend on the type of linerand the gas and liquids management strategyemployed in a unit.

B. Technical Considerationsfor Selecting CoverMaterials

Several environmental and engineering con-cerns can affect cover materials and should beconsidered in the choice of those materials.

How can climate affect a final

cover?

Freeze and thaw effects can lead to thedevelopment of microfractures in low perme-ability soil layers. These effects also can causethe realignment of interstitial fines (silts andclays), thereby increasing the hydraulic con-ductivity of the final cover. As a result, youshould determine the maximum depth offrost penetration at a site and design coversaccordingly. In other words, barrier layersshould be below the maximum frost penetra-tion depth. Information regarding the maxi-mum frost penetration depth for a particulararea can be obtained from the NaturalResource Conservation Service with the U.S.Department of Agriculture, local utilities,construction companies, local universities, orstate agencies. Figure 1 illustrates the regionaldepth of frost penetration. You should ensurethat vegetation layers are thick enough thatlow permeability soil layers in the final coverare placed below the maximum frost penetra-tion depth.

How can settlement and subsi-

dence affect a final cover?

When waste decomposes and consolidates,settlement and subsidence can result.Excessive settlement and subsidence can sig-nificantly impair the integrity of the finalcover system by causing ponding of water onthe surface, fracturing of low permeabilityinfiltration layers, and failure of geomem-branes. The degree and rate of waste settle-ment are difficult to estimate, but they shouldbe considered during design and developmentof closure plans. Waste settlement should alsobe considered when determining the timing ofclosure. Steps should be taken to minimizethe degree of settlement that will occur afterthe final cover system has been installed.

1 USDA Universal Soil Loss Equation: X = RKLSCP where: X = Soil loss (tons/acre/year); R = Rainfall ero-sion index; K = Soil erodibility index; L = Slope length factor; S = Slope gradient factor; C = Crop man-agement factor; P = Erosion control practice. For minimal long-term care X < 2.0 tons/acre/year.


How can erosion affect the per-

formance of a final cover?

Erosion can adversely affect the perfor-mance of the final cover of a unit by causingrills that require maintenance and repair.Extreme erosion can lead to the exposure ofthe infiltration layer, initiate or contribute tosliding failures, or expose the waste.Anticipated erosion due to surface-waterrunoff for a given design criteria can beapproximated using the USDA Universal SoilLoss Equation1 (U.S. EPA, 1989a). By evaluat-ing erosion loss, you might be able to opti-mize the final cover design to reducemaintenance through selection of the bestavailable soil materials. A vegetative cover notonly improves the appearance of a unit, but italso controls erosion of the final cover.

The vegetation components of the erosionlayer should have the following characteristics:

• Locally adapted perennial plants thatare resistant to various climaticchanges reasonably expected to occurat the site.

• Roots that will not disrupt the low-permeability layer.

• The ability to thrive in low-nutrientsoil with minimum nutrient addition.

• The ability to survive and functionwith little or no maintenance.

Why are interfacial and internal

friction properties for cover com-

ponents important?

Adequate friction between cover compo-nents, such as geomembrane barrier layersand soil drainage layers, as well as betweenany geosynthetic components, is needed toprevent extensive slippage or interfacial shear.Water and ice can affect the potential for

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Figure 1. Regional Depth of Frost Penetration in Inches

Source: U.S. EPA, 1989a.


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cover components to slip. Sudden sliding cantear geomembranes or cause sloughing ofearthen materials. Internal shear can also be aconcern for composite or geosynthetic clayliner materials. Measures to improve stabilityinclude using flatter slopes or texturedgeosynthetic membranes, geogrids designedto resist slipping forces, otherwise reinforcingthe cover soil, and providing drainage.

Can dry soil materials affect a

final cover?

Desiccation, the natural drying of soilmaterials, can have an adverse affect on thesoil layers compromising the final cover.Although this process is most commonlyassociated with layers of low permeabilitysoil, such as clay, it can cause problems withother soil types as well. Desiccation causescracks in the soil surface extending down-ward. Cover layers are not very thick, andtherefore these cracks can extend through anentire layer, radically changing its hydraulicconductivity or permeability. Care should betaken to detect desiccation at an early stage intime to mitigate its damage. Also, the tenden-cy for final covers to become dry makes rootpenetration even more of a problem in thatplants respond to drought by extending theirroot systems downward.

Can plants and animals have an

effect on a final cover?

When selecting the plant species toinclude in the vegetative cover of a wastemanagement unit, you should consider thepotential for root systems to grow throughsurface cover layers and penetrate underlyingdrainage and barrier layers. Such penetrationwill form preferential pathways for waterinfiltration and compromise the integrity ofthe final cover system. Similarly, the presenceof burrowing animals should be foreseenwhen designing the final cover system. Suchanimals can burrow in the surface layers and

can potentially breach the underlying barrierlayer. Strategies for mitigating the effectsdescribed here are discussed below in thecontext of protection layers composed ofgravel or cobbles.

Is it necessary to stabilize wastes?

Before installing a final cover, liquid orsemi-liquid wastes might need to be stabi-lized or solidified. Stabilization or solidifica-tion might be necessary to allow equipmenton the unit to install the final cover or toensure adequate support, or bearing capacity,for the final cover. With proper bulk covertechnique, it might be feasible to place thecover over a homogeneous, gel-like, semi-liq-uid waste. When selecting a stabilization orsolidification process, it is important to con-sider the effectiveness of the process and itscompatibility with the wastes. Performancespecifications for stabilization or solidificationprocesses include leachability, free-liquid con-tent, physical stability, bearing capacity, reac-tivity, ignitability, biodegradability, strength,permeability, and durability of the stabilizedand solidified waste. You should considerseeking professional assistance to properlystabilize or solidify waste prior to closure.

Where solidification is not practical, youshould consider reinforcement and construc-tion of a specialized lighter weight cover sys-tem over unstable wastes. This involves usingcombinations of geogrids, geotextiles,geonets, geosynthetic clay liners, andgeomembranes. For more detail on this prac-tice, consult references such as the paper byRobert P. Grefe, Closure of Papermill SludgeLagoons Using Geosynthetics and SubsequentPerformance, and the Geosynthetic ResearchInstitute proceedings, Landfill Closures:Geosynthetics Interface Friction and NewDevelopments, cited in the Resources section.


How can wastes be stabilized?

Many stabilization and solidificationprocesses require the mixing of waste withother materials, such as clay, lime, and ash.These processes include either sorbents orencapsulating agents. Sorbents are nonreac-tive and nonbiodegradable materials that soakup free liquids to form a solid or near-solidmass. Encapsulating agents enclose wastes toform an impermeable mass. The following areexamples of some commonly used types ofwaste stabilization and solidification methods.

• Cement-based techniques. Portlandcement can use moisture from thewaste (sludge) for cement hydration.The end product has high strength,good durability, and retains wasteeffectively.

• Fly ash or lime techniques. A com-bination of pozzolanic fly ash, lime,and moisture can form compoundsthat have cement-like properties.

• Thermoplastic techniques. Asphalt,tar, polyolefins, and epoxies can bemixed with waste, forming a semi-rigid solid after cooling.

• Organic polymer processes. Thistechnique involves adding and mixingmonomer with a sludge, followed byadding a polymerizing catalyst. Thistechnique entraps the solid particles.

After evaluating and selecting a stabilizationor solidification process, you should conductpilot-scale tests to address issues such as safe-ty, mix ratios, mix times, and pumping prob-lems. Testing will help assess the potential foran increase in waste volume. It will also helpto plan the production phase, train operators,and devise construction specifications.

When conducting full-scale treatmentoperations, options exist for adding and mix-ing materials. These options might include in

situ mixing and mobile plant mixing. In situmixing is the simplest technique, using com-mon construction equipment, such as back-hoes, excavators, and dump trucks. In situmixing is most suitable where large amountsof materials are added to stabilize or solidifythe waste. The existing waste managementarea, such as a surface impoundment, can beused as the mixing area. The in situ mixingprocess is open to the atmosphere, so envi-ronmental and safety issues, such as odor,dust, and vapor generation, should be takeninto consideration. For mobile plant mixing,wastes are removed from the unit, mechani-cally mixed with treatment materials in aportable processing vessel, and depositedback into the unit. Mobile plant mixing isgenerally used for treating sludges and otherwastes with a high liquid content.

C. Components of a FinalCover

Cover systems can be designed in a varietyof ways to accomplish closure goals. Thisflexibility allows a final cover design systemto integrate site-specific technical considera-tions that can affect performance. This sectiondiscusses the potential components or layersof a final cover system, their functions, andappropriate materials for each layer. Since thematerials used in cover systems are the sameas those used in liner systems, refer toChapter 7, Section B–Designing andInstalling Liners for a more detailed discus-sion of the engineering properties of the vari-ous materials.

Table 1 presents the types of layers andtypical materials that might exist in a finalcover. The minimum appropriate thicknessesof each of the five types of layers dependsupon many factors including site drainage,erosion potential, slopes, types of vegetativecover, type of soil, and climate.

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What function does the surface

layer serve?

The role of the surface layer in the final coversystem is to promote the growth of native, non-woody plant species, minimize erosion, restorethe aesthetics of the site, and protect the barrierlayer. The surface layer should be thick enoughso that the root systems of the plants do notpenetrate the underlying barrier layer. The vege-tation on the surface layer should be resistant todrought and temperature extremes, able to sur-vive and function with little maintenance, andalso be able to maximize evapotranspiration,which will limit water infiltration to the barrierlayer. It is recommended that you consult withagriculture or soil conservation experts concern-ing appropriate cover vegetation. Finally, thesurface layer should be thick enough to with-stand long-term erosion and to prevent desicca-tion and freeze/thaw effects of the barrier layer.The recommended minimum thickness for thesurface layer is at least 12 inches. The stateagency can help to determine the appropriateminimum thickness in cold climates to protectagainst freeze-thaw effects.

What types of materials can be

used in the surface layer?

Topsoil has been by far the most common-ly used material for surface layers. The princi-pal advantages of using topsoil in the surfacelayer include its general availability and itssuitability for sustaining vegetation. When top-soil is used as a surface layer, the roots ofplants will reinforce the soil, reduce the rate oferosion, decrease runoff, and remove waterfrom the soil through evapotranspiration. Toachieve these benefits, however, the soilshould have sufficient water-holding capacityto sustain plant growth. There are some con-cerns with regard to using topsoil. For exam-ple, topsoil requires ongoing maintenance,especially during periods of drought or heavyrainfall. Prolonged drought can lead to crack-ing in the soil, creating preferential pathwaysfor water infiltration. Heavy rainfall can lead toerosion causing rills or gullies, especially onnewly-seeded or steeply sloping covers. If thetopsoil does not have sufficient water holdingcapacity, it can not adequately support surfaceplant growth, and evapotranspiration can

Layer Type of Layer Typical Materials

1 Surface (Erosion, Vegetative Cover) Topsoil, Geosynthetic Erosion Control Layer, Layer Cobbles

2 Protection Layer Soil, Recycled or Reused Waste Materials, Cobbles

3 Drainage Layer Sand and/or Gravel, Geonet or Geocomposite,Chipped or Shredded Tires

4 Barrier (Infiltration) Layer Compacted Clay, Geomembrane, Geosynthetic ClayLiner

5 Foundation/Gas Collection Layer Sand or Gravel, Soil, Geonet or Geotextile,Recycled or Reused Waste Material

Table 1Types of Layers in Final Cover Systems

Source: Jesionek et al., 1995


excessively dry the soils. In this case, irrigationwill be required to restore the water balancewithin the soil structure. Topsoil is also vulner-able to penetration by burrowing animals.

Geosynthetic erosion control material canbe used as a cover above the topsoil to limiterosion prior to the establishment of a maturevegetative cover. The geosynthetic material caninclude embedded seeds to promote plantgrowth, and can be anchored or reinforced toadd stability on steeply sloped areas.Geosynthetic material, however, does notenhance the water-holding capacity of the soil.In arid or semi-arid areas, therefore, the soilmight still be prone to wind and water erosionif its water-holding capacity is insufficient.

Cobbles can be a suitable material for thesurface layer in arid areas or on steep slopeswhich might hinder the establishment of veg-etation. If they are large enough they willprovide protection from wind and water ero-sion without washout. Cobbles can also pro-tect the underlying barrier layer fromintrusion by burrowing animals, but cobblesmight not be available locally, and their usedoes not protect the underlying barrier layerfrom water infiltration. Because cobbles createa porous surface through which water canpercolate, they do not ordinarily support veg-etation. Wind-blown soil material can fillvoids between cobbles, and plants can estab-lish themselves in these materials. This plantmaterial should be removed, as its roots arelikely to extend into the underlying barrierlayer in search of water.

What function does the protec-

tion or biotic barrier layer serve?

A protection or biotic barrier layer can beadded below the surface layer, but above thedrainage layer, to protect the latter from

intrusion by plant roots or burrowing ani-mals. This layer adds depth to the surfacelayer, increasing its water storage capacityand protecting underlying layers from freez-ing and erosion. In many cases, the protec-tion layer and the surface layer are combinedto form a single cover layer.


used in the protection layer?

Soil will generally be the most suitablematerial for this layer, except in cases wherespecial design requirements exist for the pro-tection layer. The advantages and disadvan-tages of using soil in the protection layer arethe same as those stated above in the discus-sion of the surface layer topsoil. Factorsimpacting the thickness and type of soil to useas a protection layer include freeze and thawproperties and the interaction between the soiland drainage layers. Other types of materialsthat can be used in the protection layerinclude cobbles with a geotextile filter, graveland rock, and recycled or reused waste.

Cobbles with a geotextile filter can forma good barrier against penetration by plantroots and burrowing animals in arid sites.The primary disadvantage is that cobbleshave no water storage capacity and allowwater percolation into underlying layers.

Gravel and rock are similar to cobblessince they can form a good barrier againstpenetration by plant roots and burrowing ani-mals. Again, this use is usually only consid-ered for arid sites, because gravel and rockshave no water storage capacity and allowwater percolation into underlying layers.

Recycled or reused waste materials suchas fly ash and bottom ash can be used in theprotection layer, when available. Check withthe state agency to verify that use of these

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materials is allowable. The advantages ofusing these materials in the protection layerare that they store water that has infiltratedpast the surface layer, which can then bereturned to the surface through evapotrans-piration, and that they offer protectionagainst burrowing animals and penetration byroots. If planning to use waste material in theprotection layer, consider its impact on sur-face runoff at the unit’s perimeter. Designcontrols to ensure runoff does not contributeto surface-water contamination. ConsultChapter 6–Protecting Surface Water for moredetails on designing runoff controls.

What function does the drainage

layer serve?

A drainage layer can be placed below thesurface layer, but above the barrier layer, todirect infiltrating water to drainage systems atthe toe of the cover (see Figure 2) or to inter-mittent benches on long steep slopes. For

drainage layers, the thickness will depend onthe level of performance being designed andthe properties of available materials. Forexample, some geonet composites, with athickness of less than 1 inch, have a transmis-sivity equal to a much thicker layer of aggre-gate or sand. The recommended thickness ofthe high permeability soil drainage layer is 12inches with at least a 3 percent slope at thebottom of the layer. Based on standard prac-tice, the drainage layer should have ahydraulic conductivity in the range of 10-2 to10-3 cm/sec. Water infiltration control througha drainage layer improves slope stability byreducing the duration of surface and protec-tion layer saturation. In this role, the drainagelayer works with vegetation to remove infil-trating water from the cover and protect theunderlying barrier layer. If this layer drainsthe overlying soils too well, it could lead tothe need for irrigation of the surface layer toavoid desiccation.


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Figure 2. Drainage Layer Configuration



Another consideration for design ofdrainage layers is that the water should dis-charge freely from the toe of the cover or inter-mittent benches. If outlets become plugged orare not of adequate capacity, the toe of theslope can become saturated and potentiallyunstable. In addition, when designing thedrainage layer, you should consider using flex-ible corrugated piping in conjunction witheither the sand and gravel or the gravel withgeotextile filter material to facilitate the move-ment of water to the unit perimeter.

What materials can be used in

the drainage layer?

Sand and gravel are a common set ofmaterials used in the drainage layer. Theprincipal consideration in their use is thehydraulic conductivity required by the overalldesign. There can be cases in which thedesign requires the drainage of a largeamount of water from the surface layer, andthe hydraulic properties of the sand and grav-el layer might be insufficient to meet theserequirements. The advantages of using sandand gravel in the drainage layer include theability to protect the underlying barrier layerfrom intrusion, puncture, and temperatureextremes. The principal disadvantage to thesematerials is that they are subject to intrusionsfrom the overlying protective layer that canalter their hydraulic conductivity. Similarly,fines in the sand and gravel can migratedownslope, undermining the stability of thecover slope. A graded filter or a geotextile fil-ter can be used to separate and protect thesand and gravel from intrusions by the over-lying protection layer.

Gravel with a geotextile filter is also awidely-used design, whose applicability canbe limited by the local availability of materi-als. The gravel promotes drainage of waterfrom the overlying layers, while the geotextilefilter prevents the clogging of granular

drainage layers. Again, be aware of the possi-bility that a gravel drainage layer might drainoverlying soils so well that irrigation of thesurface layer might become necessary. Theprincipal advantage to a gravel/geotextiledrainage layer is the engineering community’sconsiderable body of knowledge regardingtheir use as drainage materials. Other advan-tages include their ability to protect underly-ing layers from intrusion, puncture,temperature extremes, and their commonavailability. The geotextile filter provides acushion layer between the gravel and theoverlying protection layer.

Geonet and geotextile filter materials canbe used to form an effective drainage layerdirectly above a compacted clay or geomem-brane liner (see Figure 3). They are a suitablealternative especially in cases where othermaterials, such as sand and gravel, are notlocally available. The principal advantage isthat lightweight equipment can be used during installation, reducing the risk of dam-aging the underlying barrier layer.

The disadvantages associated with geonetand geotextile materials are that they providelittle protection for the barrier layer againstextreme temperature changes, and there canbe slippage between the interfaces betweenthe geomembrane, geotextile, and low perme-

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Figure 3. Geonet with Geotextile Filter Design

for Drainage Layer


ability soil barrier materials. The use of tex-tured materials can be considered to addressslippage. Furthermore, problems can arise inthe horizontal seaming of the geotextiledrainage layer on long slopes.

Chipped or shredded tires are an addi-tional option for drainage layer materials.Chipped or shredded tires have been used forbottom drainage layers in the past and mightbe suitable for cover drainage layers as well.One caution concerning the use of chippedor shredded tires is possible metal contami-nants, or pieces of metal that could damage ageomembrane liner. You should consult withthe state agency to determine whether thisoption is an acceptable practice.

What function does the barrier

layer serve?

The barrier layer is the most critical com-ponent of the cover system because it pre-vents water infiltration into the waste. It alsoindirectly promotes the storage and drainageof water from the overlying protection andsurface layers, and it prevents the upwardmovement of gases. This layer will be the leastpermeable component of the final cover sys-tem. Typically, the hydraulic conductivity of abarrier layer is between 10-9 to 10-7 cm/sec.


used in the barrier layer?

Single compacted clay liners (CCLs) arethe most common material used as barrierlayers in final cover systems. CCL popularityarises largely because of the local availabilityof materials and the engineering community’sextensive experience with their use. Dryingand subsidence are the primary difficultiesposed by CCLs. When the clay dries, cracksappear and provide preferential pathwaysalong which water can enter the waste, pro-moting leachate formation, waste decomposi-tion, and gas formation (when methane

producing waste is present). Dry waste mater-ial and gas formation within the unit con-tribute to drying from below, while a range ofclimatological conditions, including drought,can affect CCLs from above. Even withextremely thick surface and protection layers,CCLs can still undergo some desiccation.

Clay liners are also vulnerable to subsi-dence within the waste unit. This problemcan first manifest itself during liner construc-tion. As the clay is compacted with machin-ery, the waste might not provide a stable,even foundation for the compaction process.This will make it difficult to create the evenlymeasured lifts comprising the liner. As wastesettles over time, depressions can form alongthe top of the CCL. These depressions putdifferential stresses on the liner, causingcracks which compromise its integrity. Forinstance, a depression of only 5 to 11 inchesacross a 6-foot area can be sufficient to crackthe liner materials.

Single geomembrane liners are sheets ofa plastic polymer combined with other ingre-dients to form an effective barrier to waterinfiltration. Such liners are simple andstraightforward to install, but they are rela-tively fragile and can be easily puncturedduring installation or by movement in surfacelayer materials. The principal advantage of ageomembrane is that it provides a relativelyimpermeable barrier with materials that aregenerally available. It is not damaged by tem-perature extremes and therefore does notrequire a thick surface layer. The geomem-brane is more flexible than clay and not asvulnerable to cracking as a result of subsi-dence within the unit. The principal disad-vantage is that it provides a point of potentialslippage at the interface with the cover soils.Such slippage can tear the geomembrane,even if it is anchored.

Single geosynthetic clay liners (GCLs)are composed of bentonite clay supported by


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geotextiles or geomembranes held togetherwith stitching or adhesives. These liners arerelatively easy to install and have some self-healing capacity for minor punctures. Theyare easily repaired by patching. The main dis-advantages include low shear strength, lowbearing capacity, vulnerability to puncturedue to relative thinness, and potential forslippage at interfaces with under- and overly-ing soil materials. When dry, their permeabil-ity to gas makes GCLs unsuitable as a barrierlayer for wastes that produce gas, unless theclay will be maintained in a wet state for theentire post-closure period.

Geomembrane with compacted clay lin-ers (CCLs) can be used to mitigate the short-comings of each material when used alone. Inthis composite liner, the geomembrane acts toprotect the clay from desiccation, while pro-viding increased tolerance to differential set-tlement within the waste. The clay acts toprotect the geomembrane from punctures andtearing. Both components act as an effectivebarrier to water infiltration. The principal dis-advantage is slippage between the geomem-brane and surface layer materials.

Geomembrane with geosynthetic clay lin-ers (GCLs) can also be used as a barrier layer.As with geomembrane and CCL combinations,each component serves to mitigate the weak-ness of the other. The geosynthetic material isless vulnerable than its clay counterpart tocracking and has a moderate capacity to self-heal. The geomembrane combined with theGCL is a more flexible cover and is less vulner-able to differential stresses from waste settle-ment. Neither component is readily affected byextreme temperature changes, and both worktogether to form an effective barrier layer. Formore information on the properties of geosyn-thetic clay liners, including their hydrationafter installation, refer to Chapter 7, SectionB–Designing and Installing Liners. The poten-tial disadvantage is slippage between the upperand lower surfaces of the geomembrane and

some types of GCL and other surface layermaterials. The geomembrane is still vulnerableto puncture, so placement of cover soils isimportant to minimize such damage.

Textured geomembranes can be used toincrease the stability of cap side slopes.Textured geomembranes are nearly identicalto standard “smooth” geomembranes differingonly in the rough or textured surface that hasbeen added. This textured surface increasesthe friction between the liner and soils andother geosynthetics used in the cap, and canhelp prevent sliding failures. In general, tex-tured geomembranes are more expensive thancomparable “smooth” geomembranes.

Using textured geomembranes allows capdesigners to employ steeper slopes which canincrease the available airspace in a wastemanagement unit, and therefore increase itscapacity. Textured geomembranes also helpkeep cover soil in place improving overallliner stability on steep slopes. The degree towhich textured geomembranes will improvefrictional resistance (friction coefficients/fric-tion angles) will vary from site-to-sitedepending upon the type of soil at the siteand its condition (e.g., moisture content).

Textured geomembranes are manufacturedby two primary methods. Some texturedgeomembranes have a friction coating layeradded to standard “smooth” geomembranesthrough a secondary process. Others are tex-tured during the initial production process,meaning textured layers are coextruded aspart of the liner itself. Textured geomem-branes can be textured on one or both sides.

Textured geomembranes are seam-weldedby the same technologies as standardgeomembranes. Due to their textured surface,however, seam welds can be less uniformwith textured liners than with normal liners.Some textured geomembranes have smoothedges on the top and bottom of the sheet toallow for more uniform seam welding.

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What function does the gas col-

lection layer serve?

The role of the gas collection layer is tocontrol the migration of gases to collectionvents. This collection layer is a permeablelayer that is placed above the foundationlayer. It is often used in cases where the foun-dation layer itself is not the gas collectionlayer. For more information on Clean Air Actrequirements for managing gas from landfillsand other waste management units, refer toChapter 5–ProtectingAir Quality.

Gas control systemsgenerally include mech-anisms designed to con-trol gas migration andto help vent gas emis-sions into the atmo-sphere. Systems usingnatural pressure andconvection mechanismsare referred to as passivegas control systems (seeFigure 4). Examples ofpassive gas control sys-tem elements includeditches, trenches, ventwalls, perforated pipessurrounded by coarsesoil, synthetic mem-branes, and high mois-ture, fine-grained soil.Systems using mechani-cal means to remove gasfrom the unit arereferred to as active gascontrol systems. Figure5 illustrates an activegas system. Gas controlsystems can also beused as part of correc-tive action measuresshould the concentra-

tion of methane rise to dangerous levels. Aswith all aspects of a waste containment sys-tem, construction quality assurance plays acritical role in the success of a gas manage-ment system.

Gas extraction wells are an example ofactive gas control systems. For deep wells,the number, location, and extent of the pipeperforations are important. Also, the depth ofthe well must be kept safely above the linersystem beneath the waste. For continuous gas


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Figure 4. Passive Gas Venting System

Source: Robinson, W., ed. 1986. The Solid Waste Handbook: A PracticalGuide. Reprinted by permission of John Wiley & Sons, Inc.

Figure 5. Active Gas Venting System

Source: Robinson, W., ed. 1986. The Solid Waste Handbook: A PracticalGuide. Reprinted by permission of John Wiley & Sons, Inc.

collection layers beneath the barrier layer,continuity is important for both soils andgeosynthetics.

Knowing the rate of gas generation isessential to determining the quantity of gasthat can be extracted from the site. Pumpingan individual well at a greater vacuum willgive it a wider zone of influence, which isacceptable, but obviously there are points ofdiminishing marginal returns. Larger suctionpressures influence a larger region butinvolve more energy expended in the pump-ing. Pumping at greater vacuum also increas-es the potential for drawing in atmosphericair if the pumping rate is set too high.Significant air intrusion into the unit canresult in elevated temperatures and evenunderground fires. You should perform rou-tine checks of gas generation rates to betterensure that optimal pumping rates are used.

The performance of gas extraction systemsis affected by the following parameters,which should be considered when designingand operating gas systems:

• Daily cover, which inhibits freemovement of gas.

• Sludge or liquid wastes, which affectthe ease at which gas will move.

• Shallow depth of unit, which makesit difficult to extract the gas, becauseatmospheric air will be drawn induring the pumping.

• Permeability of the final cover, whichaffects the ability of atmospheric airto permeate the wastes in the unit.


used in the gas collection layer?

Sand and gravel are the most commonmaterials used for gas collection layers. Withthese materials, a filter might be needed toprevent infiltration of materials from the bar-

rier layer. Geotextile and geosyntheticdrainage composites also can make suitablegas collection layers. In many cases, these canbe the most cost-effective alternatives. Thesame disadvantages exist with these materialsin the gas collection layer as in other layers,such as slippage and continuity of flow.

With a geomembrane in the final coverbarrier system, uplift pressures will be exert-ed unless the gas is quickly and efficientlyconveyed to the wells, vents, or collectiontrenches. If this is not properly managed,uplift pressure will either cause bubbles tooccur, displacing the cover soil and appear-ing at the surface, or decrease the normalstress between the geomembrane and itsunderlying material. This problem has led toslippage of the geomembrane and all overly-ing materials creating high tensile stressesevidenced by folding at the toe of the slopeand tension cracks near the top.

D. Capillary-Break FinalCovers

The capillary-break (CB) approach is analternative design for a final cover system(see Figure 6). This system relies on the factthat for adjacent layers of fine- and coarse-textured material to be in water-potentialequilibrium, the coarse-grained material(such as crushed stone) will tend to have amuch lower water content than the fine-grained material (such as sand). Because theconductivity of water through a soil decreasesexponentially with its water content, as a soilbecomes more dry, its tendency to stay dryincreases. Therefore, as long as the strata in acapillary break remain unsaturated (remainabove the water table), the overlying fine-tex-tured soil will retain nearly all the water andthe coarse soil will behave as a barrier towater percolation due to its dryness. Sincethis phenomenon breaks down if the coarselayer becomes saturated, this alternative

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cover system is most appropriate for semiaridand desert environments.

What types of materials are used

in capillary-break covers?

The CB cover system typically consists offive layers: surface, storage, capillary-break,barrier, and foundation. The surface, barrier,and foundation layers play the same role inthe cover system as described above. Thestorage layer consists of fine material, such assilty sand. The capillary-break, or coarse,layer consists of granular materials, such asgravel and coarse sand. A fabric filter is oftenplaced between the coarse and fine layers.

E. The HydrologicEvaluation of LandfillPerformance (HELP)Model

The relative performance of various coverdesigns can be evaluated with the HydrologicEvaluation of Landfill Performance (HELP)model, developed by the U.S. Army Corps ofEngineers Waterway Experiment Station forEPA. The HELP model was designed specifi-cally to support permit writers and engineersin evaluating alternative landfill designs, butit can also be used to evaluate various finalcover designs.

The HELP model integrates runoff, perco-lation, and subsurface-water flow actions intoone model. The model can be used to esti-mate the flow of water across and through afinal cover. To achieve this, the HELP modeluses precipitation and other climatologicalinformation to partition rainfall and snowmelt into surface runoff, evaporation, anddownward infiltration through the barrierlayer to the waste.

The HELP model essentially divides awaste management unit into layers, each

defined in terms of soil type, which is relatedto the hydraulic conductivity of each. Usersfill in data collection sheets that request spe-cific information on the layers and climate,and this information is input to the model. Inperforming its calculations, the model willtake into account the reported engineeringproperties of each layer, such as slope,hydraulic conductivity, and rates of evapo-transpiration, to estimate the amount of pre-cipitation that can enter the waste unitthrough the final cover. To use the HELPmodel properly, refer to the HELP ModelUser’s Guide and documentation (U.S. EPA,1994b; U.S. EPA, 1994c). The model itself,the User’s Guide, and supporting documenta-tion can be obtained from the U.S. ArmyCorps of Engineers Web site at<www.wes.army.mil/el/elmodels>.


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Figure 6. Example of a Capillary-Break Final

Cover System

Adapted from <www.hanford.gov/eis/hraeis/eisdoc/graphics/fige-1.gif>

F. Recommended CoverSystems

The recommended final cover systems cor-respond to a waste management unit’s bot-tom liner system. A unit with a single

geomembrane bottom liner system, for exam-ple, should include, at a minimum, a singlegeomembrane in its final cover system unlessan evaluation of site-specific conditions canshow an equivalent reduction in infiltration.Table 2 summarizes the minium recommend-

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* Please consult with your state regulatory agency prior to constructing a final cover.

a The final selection of geomembrane type, thickness, and drainage layer requirements for a final covershould be design-based and consultation with your state agency is recommended.

b This recommended thickness is for high permeability soil material with at least a 3 percent slope at thebottom of the layer. Some geonet composites, with a minimal thickness of less than 1 inch, have atransmissivity equal to a much thicker layer of aggregate or sand.

c Thickness might need to be increased to address freeze/thaw conditions.

Type of Bottom Liner Recommended Cover System Thickness Hydraulic ConductivityLayers (From top layer down)a (In inches) (In cm/sec)

Double Liner Surface Layer 12 not applicableDrainage Layer 12b 1×10-2 to 1x10-3

Geomembrane 30mil(PVC)60mil (HDPE) —

Clay Layer 18 less than 1×10-5

Composite Liner Surface Layer 12 not applicableDrainage Layer 12b 1×10-2 to 1x10-3

Geomembrane 30 mil (PVC)60 mil (HDPE) —


Single Clay Liner Surface Layer 12 not applicableDrainage Layer 12b 1×10-2 to 1x10-3


Single Clay Liner in Cobble Layer 2-4 not applicablean Arid Area Drainage Layer 12b 1×10-2 to 1x10-3


Single Synthetic Liner Surface Layer 12 not applicableDrainage Layer 12b 1×10-2 to 1x10-3

Geomembrane 30 mil (PVC)60 mil (HDPE) —


Natural Soil Liner Earthen Material 24c No more permeable thanbase soil

Table 2: Minimum Recommended Final Cover Systems*

ed final cover systems based on the unit’s bot-tom liner system. While the recommendedminimum final cover systems include closurelayer component thicknesses and hydraulicconductivity, the cover systems can be modi-fied to address site-specific conditions. In

addition, you should consider whether toinclude a protection layer or a gas collectionlayer. Figures 7 through 11 display recom-mended minimum final cover systems.


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Figure 7. Recommended Final Cover System for a Unit With a Double or Composite Liner

Figure 8. Recommended Final Cover System for a Unit With a Single Clay Liner

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Figure 9. Recommended Final Cover System for a Unit With a Single Clay Liner in an Arid Area

Figure 10. Recommended Final Cover System for a Unit With a Single Synthetic Liner

While these recommendations include theuse of compacted clay, a facility managermight want to consider the use of a geomem-brane barrier layer in addition to, or in placeof, a compacted clay barrier layer. Subsidenceof a final cover constructed with a compactedclay barrier layer can allow precipitation toenter the closed unit and increase leachateproduction. The use of a geomembrane inplace of compacted clay might be more costeffective. Due to cracking or channeling orcontinued subsidence, post-closure care of acompacted clay barrier layer can be moreexpensive to maintain than a geomembranebarrier layer. A geomembrane barrier layercan also accommodate more subsidence with-out losing its effectiveness.

IV. Closure byWaste Removal

Closure by waste removal is a term thatdescribes the removal and decontaminationof all waste, waste residues, contaminatedground water, soils, and containment devices.This approach is common for waste piles andsome surface impoundments. Removal and

decontamination are complete when the con-stituent concentrations throughout the unitand any areas affected by releases from theunit do not exceed numeric cleanup levels.You should check with the state agency to seeif it has established any numeric cleanup lev-els or methods for establishing site-specificlevels. In the absence of state cleanup levels,metals and organics should be removed toeither statistically equivalent background lev-els or to maximum contaminant levels(MCLs) or health-based numbers (HBNs)2.Metals and organics might have differentcleanup levels, but they both should be basedon either local background levels or onhealth-based guidelines.

Future land use considerations can also beimportant in determining the appropriatelevel of cleanup. One tool that can be used tohelp evaluate whether waste removal isappropriate at the site is the risk-based cor-rective action (RBCA) process described inChapter 10–Taking Corrective Action. TheRBCA process provides guidance on integrat-ing ecological and human health risk-baseddecision-making into the traditional correc-tive action process.


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2 To learn about the regulatory and technical basis for MCLs, access the Integrated Risk Information System(IRIS), a database of human health effects that can result from exposure to environmental contaminants,at <www.epa.gov/iris>. Call the EPA Risk Information Hotline at 513 569-7254 for more information.

Figure 11. Recommended Final Cover System for a Unit With a Natural Soil Liner

A. Establishing BaselineConditions

A good management practice is to establishthe baseline conditions for a waste manage-ment unit. Baseline conditions include thebackground constituent concentrations at asite prior to waste placement operations.Identifying the types of contaminants thatmight be present can provide an indication ofthe potential contamination resulting from theoperation of a unit and the level of effort andresources that can be required to reach clo-sure. Naturally-occurring elevated backgroundlevels that are higher than targeted closure lev-els might be encountered. In such cases, con-sult with the state agency to determinewhether these elevated background levels are amore appropriate targeted cleanup level. Theidentification of potential contaminants willalso provide a guideline for selecting samplingparameters. If constituents other than thoseinitially identified are discovered through sub-sequent soil and water sampling, this mightindicate that contaminants are migrating fromanother source.

In some cases, waste contaminants mighthave been present at a site before a wastemanagement unit was constructed, or theymight have migrated to the site from anotherunrelated source. In these situations, closureby waste removal can still proceed, providedthat any contamination originating from theclosing unit is removed to appropriatecleanup levels. You should determine whetheradditional remediation is required underother federal or state laws, such as theResource Conservation and Recovery Act(RCRA), the Comprehensive EnvironmentalResponse, Compensation, and Liability Act(CERCLA), or state cleanup laws.

How are baseline conditions

established?

Initial soil and ground-water samplingaround, within, and below a unit will serveto identify baseline conditions. Sampling candetect contaminant levels that exceed back-ground levels or federal, state, or localhealth-based benchmarks. Contact local envi-ronmental protection officials for guidance onthe number and type of samples that shouldbe taken. If the initial round of samplingdoes not reveal any contaminant levels thatexceed benchmarks, you should proceedwith the removal of waste and the restorationof the unit. If the sampling does reveal conta-mination that exceeds the benchmarks, youshould consider ways to remediate the site incompliance with federal, state, or localrequirements.

B. Removal ProceduresProper removal procedures are vital to the

long-term, post-closure care of a unit andsurrounding land. Properly removing wastecan minimize the need for further mainte-nance, thereby saving time and money andfacilitating reuse of the land. You should per-form closure by waste removal in a mannerthat prevents the escape of waste constituentsto the soil, surface water, ground water, andatmosphere. After removing the waste, youshould remove all equipment, liners, soils,and any other materials containing waste orwaste residues. Removal verification shouldinclude specifics as to how it will be deter-mined that residues, equipment, liners, andsoils have been removed to baseline condi-tions. Finally, the land should be returned tothe appearance and condition of surroundingland areas to the extent possible consistentwith the closure and post-closure plans.

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Should a plan for waste removal

procedures be prepared?

The waste removal process should be fullydescribed in a closure plan. The removalprocess description should address estimatesof the volumes and types of waste and conta-minated equipment or structures to beremoved during closure. It should alsoinclude the types of equipment to be used,the removal pattern, and the management ofloading areas. The closure plan should alsodetail steps to be taken to minimize and pre-vent emissions of waste during closure activi-ties. For example, if activities during closureinclude loading and transporting waste intrucks, the closure plan should describe thesteps that will be taken to minimize air emis-sions from windblown dust. Proper qualityassurance and quality control during thewaste removal process will help ensure thatthe removal proceeds in accordance with thewaste removal plan. A key component of thewaste removal procedure is the considerationof proper disposal or treatment methods forany wastes or contaminated materials.

C. Disposal of RemovedWastes

When a unit is closed by removing waste,waste residues, contaminated ground water,soils, and containment devices, you shouldensure that disposal of these materials is incompliance with state law. If the compositionof the waste can not be determined usingprocess knowledge, you should test it usingprocedures such as those described in Chapter2–Characterizing Waste. Then consult with thestate agency to determine which requirementsmight apply to the waste.

D. Final Sampling andAnalysis

The purpose of final sampling and analysisis to ensure that target cleanup levels havebeen achieved. While initial sampling isintended to establish baseline levels of conta-minants, final sampling is used more as asafeguard to make sure levels have notchanged. It is important to conduct a finalsampling, in addition to the initial sampling,because removal actions can increase the con-taminant levels at the site, and sometimescontamination is overlooked in the initialbaseline sampling event. Refer to Chapter9–Monitoring Performance for a detailed dis-cussion of sampling and analysis procedures.

How should the sampling data

be used?

The results of this sampling event shouldbe compared to the results of the baselineevent, and any discrepancies should benoted. The results can be compared to per-formance measures established at the begin-ning of the closure process with state or localregulators. Closure plans incorporating wasteremoval should include a sampling andanalysis plan for the initial and final samplingand analysis efforts. The plan should specifyprocedures to ensure that sample collection,handling, and analysis will result in data ofsufficient quality to plan and evaluate closureactivities. The sampling and analysis planshould be designed to define the nature andextent of contamination at, or released from,the closing unit. The level of detail in thesampling and analysis plan should be com-mensurate with the complexity of conditionsat the closing unit.


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V. Post-Closure CareConsiderationsWhen FinalCover Is Used

For units that will close with a final cover,the following factors should be considered:

• Routine maintenance of the unit’s sys-tems, including the final cover,leachate collection and removal sys-tems, run-on and runoff controls, gasand ground-water monitoring sys-tems, and surface-water and gas qual-ity monitoring where appropriate.

• The names and telephone numbersof facility personnel for emergencies.

• Mechanisms to ensure the integrity ofthe final cover system, such as postedsigns or notifications on deeds.

• The anticipated uses of the propertyduring the post-closure period.

• The length of the post-closure careperiod.

• Costs to implement and conductpost-closure care.

• Conditions that will cause post-clo-sure care to be extended or shortened.

A. MaintenanceAfter the final cover is installed, some

maintenance and repair likely will be neces-sary to keep the cover in good working con-dition. Maintenance can include mowing thevegetative cover periodically and reseeding, ifnecessary. Repair the cover when erosion orsubsidence occurs. Maintaining healthy vege-tation will ensure the stability of slopes,reduce surface erosion, and reduce leachateproduction by increasing evapotranspiration.

A regular schedule for site inspections ofmaintenance activities during the post-closureperiod, as well as prompt repair of any prob-lems found at inspection, can help ensure theproper performance of the cover system.Maintenance of the proper thickness of sur-face and drainage layers can ensure long-termminimization of leachate production and pro-tection of geomembranes, if present.

What maintenance and repair

activities should be conducted

after the final cover has been

installed?

In the case of damage to the final cover,you should determine the cause of damage sothat proper repair measures can be taken toprevent recurrence. For example, if the dam-age is due to erosion, potential causes mightinclude the length and steepness of slopes,insufficient vegetation growth due to poorplanting, or uneven settlement of the waste.Sedimentation basins and drainage swalesshould be inspected after major storms andrepaired or cleaned, as necessary.

Components of the leachate collection andremoval system, such as leachate collectionpipes, manholes, tanks, and pumps shouldalso receive regular inspection and mainte-nance. If possible, flush and pressure-cleanthe collection systems on a regular basis toreduce sediment accumulation and to pre-vent clogging caused by biological growth.The manholes, tanks, and pumps should bevisually inspected at least annually, andvalves and manual controls should be exer-cised even more frequently, because leachatecan corrode metallic parts. Repairs will helpprevent future problems, such as leachateoverflow from a tank due to pump failure.

You should inspect and repair gas andground-water monitoring wells during thepost-closure period. Proper operation of

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monitoring wells is essential to determinewhether releases from a closed waste manage-ment unit are occurring. For example,ground-water monitoring wells should beinspected to ensure that they have not beendamaged by vehicular traffic or vandalism.Physical scraping or swabbing might be nec-essary to remove biological clogging orencrustation from calcium carbonate depositson well screens.

B. Monitoring During Post-Closure Care

Post-closure care monitoring shouldinclude the leachate collection system, sur-face-water controls, the ground-water moni-toring system where appropriate, and gascontrols where appropriate. Post-closuremonitoring will serve as your main source ofinformation about the integrity of the finalcover and liners. A reduction in the intensity(i.e., frequency) and scope of monitoringmight be warranted after some period of timeduring post-closure care. Conversely, anincrease in intensity and scope might becomenecessary due to unanticipated problems.

What should be considered when

monitoring post-closure leachate,

ground water, and gas?

The quantity of leachate generated shouldbe monitored, as this is a good indicator ofthe performance of the closure system. If theclosure system is effective, the amount ofleachate generated should decrease over time.In addition, the concentration of contami-nants in leachate should, in time, reach anequilibrium. An abrupt decline in the conta-minant concentration could mean that thecover has failed, and surface water hasentered the waste and diluted the leachate.

To ensure leachate has not contaminatedground-water supplies, you should sampleground water regularly. Regular ground-watermonitoring detects changes, or the lack there-of, in the quality of ground water. For a moredetailed discussion, consult Chapter 9–Monitoring Performance.

As no cover system is impermeable to gasmigration, and if gas production is a concernat the unit, you should install gas monitoringwells around the perimeter of the unit todetect laterally moving gas. If geomembranesare used in a cover, more gas can escape lat-erally than vertically. Gas collection systemscan also become clogged and stop performingproperly. Therefore, you should periodicallycheck gas vents and flush and pressure-cleanthose vents not working properly.

C. Recommended Lengthof the Post-Closure CarePeriod

The overall goal of post-closure care is toprovide care until wastes no longer present athreat to the environment. Threats to the envi-ronment during the post-closure care periodcan be evaluated using leachate and ground-water monitoring data to determine whetherthere is a potential for migration of waste con-stituents at levels that might threaten humanhealth and the environment. Ground-watermonitoring data can be compared to drinkingwater standards or health-based criteria todetermine whether a threat exists.

Leachate volumes and constituent concen-trations can also be used to show that theunit does not pose a threat to human healthand the environment. The threats posed bywaste constituents in leachate should be eval-uated based on the potential release ofleachate to ground and surface waters.Consequently, you should consider doingpost-closure care maintenance for as long as


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that potential exists. Individual post-closurecare periods can be long or short dependingon the type of waste being managed, thewaste management unit, and a variety of site-specific characteristics. You should contactthe appropriate state agency to determinewhat post-closure period it recommends. Inthe absence of any state guidance on theappropriate length of the post-closure period,consider a minimum of 30 years.

D. Closure and Post-ClosureCost Considerations

The facility manager of a closed industrialunit is responsible for that unit. To ensurelong-term protection of the environment, youshould account for the costs of closure andpost-closure care when making initial plans.There are guidance documents available tohelp plan for the costs associated with closinga unit. For example, guides produced by theR.S. Means Co. provide up-to-date cost esti-mates for most construction-related work,such as moving soil, and material and laborfor installing piping. Table 3 also presents anexample of a closure/post-closure cost esti-mate form. Table 4 presents a sample summa-ry cost estimating worksheet to assist indetermining the cost of closure. Also youshould consider obtaining financial assurancemechanisms so that the necessary funds willbe available to complete closure and post-clo-sure care activities if necessary. Financialassurance planning encourages internalizationof the future costs associated with waste man-agement units and promotes proper designand operating practices, because the costs forclosure and post-closure care are often lessfor units operated in an environmentally pro-tective manner. You should check with thestate agency to determine whether financialassurance is required and what types offinancial assurance mechanisms might beacceptable.

The amount of financial assurance thatmight be necessary is based on site-specificestimates of the costs of closure and post-clo-sure care. The estimates should reflect thecosts that a third party would incur in con-ducting closure and post-closure activities.This recommendation ensures adequate fundswill be available to hire a third party to carryout necessary activities. You should considerupdating the cost estimates annually toaccount for inflation and whenever changesare made to the closure and post-closureplans. For financial assurance purposes, if astate does not have a regulation or guidanceregarding the length of the post-closure careperiod, 30 years could be used as a planningtool for developing closure and post-closurecost estimates.

Financial assurance mechanisms do notforce anyone to immediately provide fullfunding for closure and post-closure care.Rather, they help to ensure the future avail-ability of such funds. For example, trustfunds can be built up gradually during theoperating life of a waste management unit. Byhaving an extended “pay-in” period for trustfunds, the burden of funding closure andpost-closure care will be spread out over theeconomic life of the unit. Alternatively, con-sider the use of a corporate financial test orthird-party alternative, such as surety bonds,letters of credit, insurance, or guarantees.

What costs can be expected to

be associated with the closure of

a unit?

The cost of constructing a final cover orachieving closure by waste removal willdepend on site-specific activities. You shouldconsider developing written cost estimatesbefore closure procedures begin. For closureby means of a final cover, the cost of con-structing the final cover will depend on thecomplexity of the cover profile, final slope


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* Developed from New Jersey Department of Environmental Protection, Bureau of Landfill EngineeringLandfill Permits.

Provisions Total Closure Total Post- Total Closure/Costs Yrs. ( - ) Closure Costs Post-Closure

Yrs. ( - ) Costs Yrs. ( - )

i Soil Erosion and Sediment Control Plan NA

ii Final Cover NA

iii Final Cover Vegetation NA

iv Maintenance Program for Final Cover and NAFinal Cover Vegetation

v Maintenance Program for Side Slopes NA

vi Run-On and Runoff Control Program NA

vii Maintenance Program for Run-On and Runoff NAControl System

viii Ground-water Monitoring Wells NA

ix Maintenance Program for Ground-water NAMonitoring Wells

x Ground-water Monitoring NA

xi Methane Gas Venting or Evacuation System NA

xii Maintenance Program for Methane Gas NAVenting or Evacuation System

xiii Leachate Collection and/or Control System NA

xiv Maintenance Program for Leachate Collection NAand/or Control System

xv Facility Access Control System NA

xvi Maintenance Program for Facility Access NAControl System

xvii Measures to Conform the Site to NASurrounding Area

xviii Maintenance Program for Site Conformance NAMeasures

xix Construction Quality Assurance and NAQuality Control

TOTAL COSTS

Table 3: Example Closure/Post-Closure Cost Estimate Form* (All Costs Shown in ($000)

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Provisions Total Post- Year Year Year Year Year Year Year Closure Costs #1 #2 #3 #4 #5 #6 #7

i Soil Erosion and Sediment Control Plan NA

ii Final Cover NA

iii Final Cover Vegetation NA

iv Maintenance Program for Final Cover and Final Cover Vegetation

v Maintenance Program for Side Slopes

vi Run-On and Runoff Control Program NA

vii Maintenance Program for Run-On and Runoff Control System

viii Ground-water Monitoring Wells NA

ix Maintenance Program for Ground-water Monitoring Wells

x Ground-water Monitoring

xi Methane Gas Venting or Evacuation NASystem

xii Maintenance Program for Methane Gas Venting or Evacuation System

xiii Leachate Collection and/or Control NASystem

xiv Maintenance Program for Leachate Collection and/or Control System

xv Facility Access Control System NA

xvi Maintenance Program for Facility Access Control System

xvii Measures to Conform the Site to NASurrounding Area

xviii Maintenance Program for Site Conformance Measures

xix Construction Quality Assurance and NAQuality Control

TOTAL COSTS

Table 3: Example Closure/Post-Closure Cost Estimate Form (Cont’d)


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Worksheet generated from CostPro©: Closure and Post-Closure Cost Estimating Software. Available fromSteve Jeffords of Tetra Tech EM Inc., 404 225-5514, or 285 Peach Tree Center Avenue, Suite 900,Atlanta, GA, 30303.

Table 4: Sample Summary Cost Estimating Worksheet

Summary Worksheet for Landfills

ActivitySome of the activities listed below are routine. The owner or operator Worksheet Costmight elect or be required to conduct additional activities. Italic type Number denotes worksheets for estimating the costs of those additional activities

1 Installation of Clay Layer LF-3 $

2 Installation of Geomembrane LF-4 $

3 Installation of Drainage Layer LF-5 $

4 Installation of Topsoil LF-6 $

5 Establishment of Vegetative Cover LF-7 $

6 Installation of Colloid Clay Liner LF-8 $

7 Installation of Asphalt Cover LF-9 $

8 Decontamination DC-1 $

9 Sampling and Analysis SA-2 $

10 Monitoring Well Installation MW-1 $

11 Transportation TR-1 $

12 Treatment and Disposal TD-1 $

13 Subtotal of Closure Costs (Add lines 1 through 12)

14 Engineering Expenses (Engineering expenses are typically 10% of closure $costs, excluding survey plat, certification of closure, and post-closure care.)

15 Survey Plat LF-10 $

16 Certification of Closure LF-11 $

17 Subtotal (Add engineering expenses and cost of the survey plat, certification of $closure, and post-closure care to closure costs [Add lines 12 through 16])

18 Contingency Allowance (Contingency allowances are typically 20% of closure costs, engineering expenses, cost of survey plat, cost of certification of closure, and post- closure care.) $

19 Post-Closure Care PC-1 $

TOTAL COST OF CLOSURE (Add lines 17, 18, and 19) $

contours of the cover, whether the entire unitwill be closed (or partial closures), and othersite-specific factors. For example, the compo-nents of the final cover system, such as a gas-vent layer or a biotic layer, will affect costs. Inaddition, closure-cost estimates would alsoinclude final-cover vegetation, run-on andrunoff control systems, leachate collectionand removal systems, ground-water monitor-ing wells, gas-monitoring systems and con-trols, and access controls, such as fences orsigns. Closure costs might also include con-struction quality assurance costs, engineeringfees, accounting and banking fees, insurance,permit fees, legal fees, and, where appropri-ate, contingencies for cost overruns, reworks,emergencies, and unforeseen expenses.

For closure by means of waste removal,closure costs would include the costs ofremoval procedures, decontamination proce-dures, and sampling and analysis. Closurecost estimates should also consider the costsfor equipment to remove all waste, transportit to another waste management unit, andproperly treat or dispose of it. In addition,fugitive dust emission controls, such as dustsuppression practices, might need to beincluded as a closure cost. Table 5 presentsexample estimates of average closure costs fortypical closure activities. It also presents esti-mates of typical post-closure care costs dis-cussed in more detail below.

What costs can be expected to be

associated with post-closure care?

After a waste management unit is closed,you should conduct monitoring and mainte-nance to ensure that the closed unit remainssecure and stable. Consider the costs to con-duct post-closure care and monitoring forsome period of time, such as 30 years (in theabsence of a state regulation or guidance). If aunit is successfully closed by means of wasteremoval, no post-closure care costs would be

expected. Post-closure care costs shouldinclude both annual costs, such as monitor-ing, and periodic costs, such as cap or moni-toring well replacement.

For units closed by means of a final cover,you should consider the costs for a mainte-nance program for the final cover and associ-ated vegetation. The more frequent the timingof the maintenance activities, the greater yourpost-closure care costs will be. This programmight include repair of damaged or stressedvegetation, and maintenance of side slopes.Costs to maintain the run-on and runoff con-trol systems, leachate collection and removalsystems, and ground-water and gas monitor-ing wells should also be expected. In addi-tion, sampling, analysis, and reporting costsshould be factored into the post-closure costestimates. See Table 5 above for estimates ofpost-closure care costs.

Post-closure costs should be updatedannually as a record of actual unit costs isdeveloped. Some costs, such as erosion con-trol and ground-water sampling, might bereduced over time as the vegetation on thecover matures and a meaningful amount ofmonitoring data is accumulated. Due to site-specific conditions, a shorter or longer post-closure period might be determined to beappropriate.

How can long-term financial

assurance for a unit be obtained?

Different examples of financial assurancemechanisms include trust funds, surety bond,insurance, guarantee, corporate guarantees,and financial tests. Trust funds are a methodwhereby cash, liquid assets, certificates ofdeposit, or government securities are deposit-ed into a fund controlled by a trustee, or stateagency. The trust fund amount should be suchthat the principal plus accumulated earningsover the projected life of the waste manage-ment unit would be sufficient to pay closure

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Closure Activity Cost Estimate

Estimated average total landfill closure cost $4,000,000 1

Complete site grading $1,222/acre 2

Landfill capping

Total (all capping materials & activities) $80,000 – $100,000/ acre 3

Compacted clay cap $5.17/cubic yard of clay 2

Geosynthetic clay liner cap $16,553/acre 2

Leachate collection and treatment $0.05 – $0.15/gallon 3

$0.25/gallon 2

Reclamation of area (applying 2.5 feet of top soil and seeding) $10,200/acre 3

Install ground-water monitoring wells $2,400/well 4

Install methane monitoring wells (if applicable) $1,300/well 4

Install perimeter fence $13/linear foot 4

Repair/replace perimeter fence $2.20/linear foot 2

Construct surface-water structures $1/linear foot 4

Table 5. Example Estimated Closure and Post-Closure Care Costs

Post-Closure Activity Cost Estimate(based on 30 year post-closure care period)

Estimated average total landfill post-closure care cost $1,000,000 1

Conduct annual inspections $22,000/facility/year 4

$15,000/facility/year 2

Maintain leachate collection systems $60,000 2

Conduct Post-closure ground-water monitoring $15,000 – $25,000/year 3

(sampling and analysis) $12,000/well 4

Conduct methane monitoring $7,200/well 4

Maintain perimeter fence $12/linear foot 4

Maintain surface-water structures $1/linear foot 4

Remove perimeter fence (at end of post-closure care period) $2/linear foot 4

1 ICF Incorporated. Memo to Dale Ruhter, September 11, 1996

ICF’s data show that total closure and post-closure care costs are dependent upon the size of the landfill.The size ranges and corresponding cost estimates were used to calculate the estimated average total costs.

and post-closure care costs. Surety bond,insurance, and guarantee are methods toarrange for a third party to guarantee pay-ment for closure and post-closure activities ifnecessary. A financial test is a standard, suchas an accounting ratio, net worth, bond rat-ing, or a combination of these standards, thatmeasures the financial strength of a firm. Bypassing a financial test, it is determined thatone has the financial strength to pay for clo-sure and post-closure costs.

A more detailed explanation of theseexamples and other potential financial assur-ance mechanisms is provided below. Thesemechanisms can be used individually or incombination. This Guide, however, does notrecommend specific, acceptable, financialassurance mechanisms.

• Trust funds. A trust fund is anarrangement in which one party, thegrantor, transfers cash, liquid assets,certificates of deposit, or governmentsecurities into a fund controlled by aspecial “custodian,” the trustee, whomanages the money for the benefit of

one or more beneficiaries. The trustfund should be dedicated to closureand post-closure care activities.Payments are made annually into thefund so that the full amount for clo-sure and post-closure care accumu-lates before closure and post-closurecare activities start. A copy of thetrust agreement, which describeshow the funds will be used to pay forclosure and post-closure care activi-ties, should be placed in the wastemanagement unit’s operating record.

• Surety bond. A surety bond guaran-tees performance of an obligation,such as closure and post-closurecare. A surety company is an entitythat agrees to answer for the debt ordefault of another. Payment or per-formance surety bonds are acceptablein the event an owner or operatorfails to conduct closure and post-clo-sure care activities. If you use a sure-ty bond or letter of credit, youshould establish a standby trust fund(essentially the same as a trust fund).

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2 Oklahoma Department of Environmental Quality. Table 5.2 Closure Cost Estimate and Table 5.3 PostClosure Estimate from Chapter 5 of Solid Waste Financial Assurance Program Report. December 2000.

3 Jeffrey H. Heath “Landfill Closures: Balancing Environmental Protection with Cost,” MSW Management.January/February 1996. pp. 66-70.

4 Wyoming Department of Environmental Quality, Solid and Hazardous Waste Division. Solid WasteGuideline #12: Participation in the State Trust Account. May 1994.

Size Range Cost (tons per day) (in 2000 dollars)

50 – 125 $2,700,000

126 – 275 $5,100,000

276 – 563 $8,300,000

564 – 1125 $11,800,000

Subtitle D Landfill Closure Costs

Size Range Cost (tons per day) (in 2000 dollars)

50 – 125 $820,000

126 – 275 $980,000

276 – 563 $1,400,000

564 – 1125 $1,700,000

Subtitle D Landfill Post-Closure Care Costs

Notes for Table 5

In most cases, a standby trust fund isestablished with an initial nominalfee agreed to by the owner or theoperator and the trustee. Furtherpayments into this fund are notrequired until the standby trust isfunded by a surety company. Thesurety company should be listed asan acceptable surety in Circular 570of the U.S. Department of Treasury.

• Letters of credit. A letter of credit isa formalized line of credit from abank or another institution on behalfof an owner or operator. This agree-ment states that it will make availableto a beneficiary, such as a state, a spe-cific sum of money during a specifictime period. The letter of creditshould be irrevocable and issued for1 year. The letter of credit shouldalso establish a standby trust fund.

• Insurance. An insurance policy isbasically a contract through whichone party guarantees another partymonies, usually a prescribed amount,to perform the closure or post-clo-sure care in return for premiumspaid. The policy should be issued fora face amount at least equal to thecurrent cost estimate for closure andpost-closure care. The face amountrefers to the total amount the insureris obligated to pay; actual paymentsdo not change the face amount.

• Corporate financial test. Corporatefinancial tests are a method for anowner and operator to self-guarantee

that they have the financial resourcesto pay for closure and post-closurecosts. These tests might require that acompany meet a specified net worth,a specified ratio of total liabilities tonet worth, and a specified net work-ing capital in the United States.Implicit in using a financial test is areliance on Generally AcceptedAccounting Principles (GAAP) to pro-vide fairly represented accountingdata. Your financial statements shouldbe audited by an independent certi-fied public accountant. If the accoun-tant gives an adverse opinion or adisclaimer of opinion of the financialstatements, you should use a differentfinancial assurance mechanism.

• Corporate guarantee. Under a cor-porate guarantee, a parent companyguarantees to pay for closure andpost-closure care, if necessary. Theparent company should pass a finan-cial test to show that it has adequatefinancial strength to provide theguarantee. A financial test is a wayfor guarantors to use financial data toshow that their resources are ade-quate to meet closure and post-clo-sure care costs. The guarantee shouldonly be used by firms with adequatefinancial strength.

• Other financial assurance mecha-nisms. If you consider other financialassurance mechanisms, you shouldtalk to your state to see if the mecha-nism is acceptable.


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11-34


You should consider the following while developing closure and post-closure care activities for industrialwaste management units.

■■■■ Develop a closure and post-closure plan, specifying the activities, unit type, waste type, and scheduleof the closure.

■■■■ If using a final cover to accomplish closure:

— Include the specifications for the final cover in the closure plan.

— Determine whether the waste will need stabilization or solidification prior to constructing the finalcover.

— Address site-specific factors that can affect cover performance.

— Select the appropriate materials to use for each layer of the final cover.

— Evaluate the effectiveness of the final cover design using an appropriate methodology or modelingprogram.

— Establish a maintenance plan for the cover system.

— Establish a program for monitoring the leachate collection system, ground-water quality, and gasgeneration during the post-closure period.

— Ensure proper quality assurance and quality control during final cover installation and post-clo-sure monitoring.

■■■■ If accomplishing closure by waste removal:

— Include estimates of the waste volume, contaminated soils and containment structures to beremoved during closure.

— Establish baseline conditions and check to see if the state requires numeric cleanup levels.

— Develop removal procedures.

— Develop a sampling and analysis plan.

— Ensure proper quality assurance and quality control during sampling.

■■■■ Determine what post-closure activities will be appropriate at the site.

■■■■ Estimate the costs of closure and post-closure care activities and consider financial assurance mecha-nisms to help plan for these future costs.

Performing Closure and Post-Closure Care Activity List


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ASTM. D-3987-85. Standard Test Method for Shake Extraction of Solid Waste with Water.

ASTM. Standard Methods for Examination of Water and Wastewater.

ASTM, APHA, AWWA, & WPCF. Standard Test Methods for Examination of Water and Wastewater.


Florida Department of Environmental Protection. Solid Waste Section. 1995. Municipal Solid Waste LandfillAlternate Design Closure Guidance.

Geosynthetic Research Institute. 1990. Landfill Closures: Geosynthetics Interface Friction and NewDevelopments. GRI Proceedings.

Grefe, R. P. 1989. Closure of Papermill Sludge Lagoons Using Geosynthetics and Subsequent Performance.Presented at the Twelfth Annual Madison Waste Conference. September.

Heath, Jeffrey H. 1996. “Landfill Closures: Balancing Environmental Protection with Cost,” MSWManagement. January/February. pp. 66-70.

ICF Incorporated. 1996. Memorandum to U.S. EPA: Updated Closure and Post-Closure Cost Estimates forSubtitle C. (Nevin and Brawn to Ruhter, September 11, 1996).

Jesionek, K.S., R.J. Dunn, and D.E. Daniel. 1995. Evaluation of Landfill Final Covers. Proceedings Sardinia95, Fifth International Landfill Symposium. October.

Koerner, R.M. and D.E. Daniel. 1997. Final Covers for Solid Waste Landfills and Abandoned Dumps.

Oklahoma Department of Environmental Quality. 2000. Chapter 5 of Solid Waste Financial AssuranceProgram Report.

New Jersey Department of Environmental Protection and Energy. 1994. Technical Manual for Division of SolidWaste Management Bureau of Landfill Engineering Landfill Permits.

Texas Natural Resource Conservation Commission. Industrial & Hazardous Waste Division. 1993. ClosureGuidance Documents (Draft). September.

Texas Natural Resource Conservation Commission. Industrial Solid Waste Management. 1984. “Closure andPost-Closure Estimates.” <ftp://ftp.tnrcc.state.tx.us/pub/bbs1/ihwpslib/tg10.doc>. October.

Resources

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U.S. EPA. 1996. Test Methods for Evaluating Solid Waste Physical/Chemical Methods. SW-846.

U.S. EPA. 1995. Decision-Maker’s Guide to Solid Waste Management, Second Edition. EPA530-R-95-023.

U.S. EPA. 1994a. Design, Operation, and Closure of Municipal Solid Waste Landfills. EPA625-R-94-008.

U.S. EPA. 1994b. The Hydrologic Evaluation of Landfill Performance (HELP) Model: Users Guide forVersion 3. EPA600-R-94-168a.

U.S. EPA. 1994c. The Hydrologic Evaluation of Landfill Performance (HELP) Model: EngineeringDocumentation for Version 3. EPA600-R-94-168b.

U.S. EPA. 1993. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.

U.S. EPA. 1991. Seminar Publication: Design and Construction of RCRA/CERCLA Final Covers. EPA625-4-91-025.

U.S. EPA. 1990. Sites for Our Solid Waste: a Guidebook for Effective Public Involvement. EPA530-SW-90-019.

U.S. EPA. 1989a. Seminar Publication: Requirements for Hazardous Waste Landfill Design, Construction,and Closure. EPA625-4-89-022.

U.S. EPA. 1989b. Technical Guidance Document: Final Covers on Hazardous Waste Landfills and SurfaceImpoundments. EPA530-SW-89-047.

U.S. EPA. 1988. Guide to Technical Resources for the Design of Land Disposal Facilities. EPA625-6-88-018.

U.S. EPA. 1979. Method for Chemical Analysis of Water and Wastes. EPA600-4-79-020.

Washington Department of Ecology, Hazardous Waste and Toxics Reduction Program. 1994. Guidance forClean Closure of Dangerous Waste Facilities.

Wyoming Department of Environmental Quality, Solid and Hazardous Waste Division. 1994. Solid WasteGuideline #12: Participation in the State Trust Account.

Resources (cont.)

GGlloossssaarryy

G-1

24-hour, 25-year a rainfall event of 24 hours duration and of such a magnitude that it storm event has a 4 percent statistical likelihood of occurring in any given year.

acceptance and methods used to evaluate the performance of geomembranes. While theconformance testing specific ASTM test methods vary depending on geomembrane type, rec-

ommended acceptance and conformance testing for geomembranesincludes evaluation of thickness, tensile strength and elongation, andpuncture and tear resistance testing, as appropriate.

access controls measures, such as fences or security guards, used to restrict entry to a site.

active gas control mechanical means, such as a vacuum or pump, to forcibly remove gas systems from a waste management unit.

adsorption the process by which molecules of gas, liquid, or dissolved solids adhereto the surface of other particles, such as activated carbon or clay.

aerobic processes a biochemical process or condition occurring in the presence of oxygen.

agronomic rate in land application, a waste application rate designed to provide theamount of nitrogen needed by a crop or vegetation to attain a desiredyield, while minimizing the amount of nitrogen that will pass below theroot zone of the crop or vegetation to ground water.

anaerobic processes a biological process that reduces organic matter to compounds such asmethane and carbon dioxide in an oxygen-free environment.

anchor trench a long, narrow ditch along the perimeter of a unit cell in which the edgesof a geomembrane are buried or secured.

annular seal impermeable material used to prevent infiltration of surface water andcontaminants into the space between the borehole wall and the ground-water well casing.

attenuation the process by which a compound is reduced in concentration over timethrough chemical, physical, and biological processes such as adsorption,degradation, dilution, and transformation.

Atterberg limits a soil’s plastic limit (percent moisture at which soil transitions from solidto plastic) and its liquid limit (percent moisture at which soil transitionsfrom plastic to liquid); useful in characterizing soil plasticity when design-ing liners with clay soils.

Glossary

GGlloossssaarryy

G-2

barrier (infiltration) in a final cover system, a layer preventing water infiltration into thewaste, indirectly promoting the storage and drainage of water from theoverlying protection and surface layers, and preventing the upwardmovement of gases.

barrier walls low permeability partitions used to direct uncontaminated ground-waterflow around a disposal site or to prevent contaminated material frommigrating from a site.

bathtub effect the buildup of leachate within a unit that occurs when the cover systemis more permeable than the liner. Leachate accumulates due to the infil-tration rate through the cover system exceeding the exfiltration ratethrough the liner system.

bench-scale a study used to evaluate the effectiveness of one or more potentialtreatability study treatment remedies. It establishes the validity of a technology and gener-

ates data indicating the remedy’s potential to meet performance goals.

berm a raised flow diversion structure made from compacted earth or rock filland used to buttress a slope and prevent run-on from entering a wastemanagement unit.

best management measures used to reduce or eliminate contaminant releases to the practices (BMPs) environment. BMPs can take the form of a process, activity, or physical

structure.

bioaccumulation the uptake and concentration of substances, such as waste constituents,by exposed organisms. This phenomenon has the potential to cause highconcentrations especially in the tissues of higher predators.

biochemical oxygen the amount of oxygen consumed in the biological processes that break demand (BOD) down organic matter (typically measured in mg oxygen per L waste or

leachate).

biodegradable significant component of waste used in land application. Carbon-basedorganic matter material derived from biological organisms; eventually decomposed by

microbes into nontoxic products often useful as plant nutrients.(Compare to synthetic organic compounds.)

biological treatment a process relying primarily on oxidative or reductive mechanisms initiat-ed by microorganisms to stabilize or de-toxify a waste or leachate.Biological treatment can rely either on aerobic or anaerobic processes.

Glossary (cont.)

GGlloossssaarryy

Glossary (cont.)

G-3

blanks samples of ground water, air, or other media, collected to determinebackground contaminants in the field; used for comparison purposeswhen analyzing monitoring data.

borrow pit a location where soils are excavated for use as fill or for compactioninto liners.

buffer zone an area between waste management units and other nearby properties,such as schools. Buffer zones provide time and space to shield sur-rounding properties from ongoing activities and disruptions associatedwith waste management activities.

calcium carbonate a measure of a waste’s ability to neutralize soil acidity—its buffering equivalent (CCE) capacity—compared to pure calcium carbonate.

capillary-break (CB) an alternative design for a final cover system that exploits the relative approach differences in porosity between soil types to inhibit water infiltration.

carbon to nitrogen in land application, the ratio of the relative quantities of these two ratio elements in a waste. Carbon is associated with the biodegradable

organic matter in a waste, and the carbon to nitrogen ratio reflects thelevel of inorganic nitrogen available in the soil for plant growth.

cation exchange the ability of a soil to take up and give off positively charged ions—a capacity process which affects the movement of metals in soil.

chain-of-custody a document tracking possession of samples from the time of collection record through laboratory analysis. A chain-of-custody record generally

includes the date and time of collection, signatures of those involvedin the chain of possession, time and dates of possession, and othernotations to allow tracking of samples.

chemical oxygen a measure of the oxygen equivalent of the organic matter in a waste demand (COD) or leachate that is susceptible to oxidation by a strong chemical oxi-

dant such as chromate. COD is used to determine the degree of conta-mination of a waste or leachate that is not readily biodegradable (seebiochemical oxygen demand.)

chemical seaming the use of solvents, cement, or an adhesive to join panels or rolls of aliner. Chemical seaming processes include chemical fusion and adhe-sive seaming.

chemical treatment a class of processes in which chemicals are added to wastes or to cont-aminated media to reduce toxicity, mobility, or volume.

GGlloossssaarryy

Glossary (cont.)

G-4

closure termination of the active life of a waste management accompanied byone of the following measures: 1) use of engineered controls, such as afinal cover, and post-closure care activities to maintain and monitorthe controls, or 2) removal of waste and contaminated containmentdevices and soils.

closure plan a document describing the procedure envisioned for the termination ofa waste management unit’s active life. Topics addressed often includefuture land use, whether wastes will be removed or left in place at clo-sure, closure schedule, steps to monitor progress of closure actions,contingency plans, and final cover information.

collection and an area that retains runoff long enough to allow solids/particles that sedimentation basin are suspended in and being transported by surface water to settle out

by gravity.

compacted clay a hydraulic barrier layer composed of natural mineral materials liner (CCL) (natural soils), bentonite-soil blends, and other materials placed and

compressed in layers called lifts.

construction quality a planned series of observations and tests of unit components, such as assurance (CQA) liners, as they are being built. CQA is designed to ensure that the com-

ponents meet specifications. CQA testing, often referred to as accep-tance inspection, provides a measure of final product quality and itsconformance with project plans and specifications.

construction quality an ongoing process of measuring and controlling the characteristics of control (CQC) unit components, such as liners, in order to meet manufacturer’s or

project specifications. CQC inspections are typically performed by thecontractor to provide an in-process measure of construction qualityand conformance with the project plans and specifications, therebyallowing the contractor to correct the construction process if the quali-ty of the product is not meeting the specifications and plans.

control charts a statistical method of evaluating ground-water monitoring data usinghistorical data for comparison purposes. Appropriate only for initiallyuncontaminated wells.

corrective action the process of taking appropriate steps to remediate any contamination.

critical habitat areas which are occupied by endangered or threatened species andwhich contain physical or biological features essential to the prolifera-tion of the species.

GGlloossssaarryy

Glossary (cont.)

G-5

daily cover a level of soil and/or other materials applied at the end of a day afterwaste has been placed, spread, and compacted. Covering the wastehelps control nuisance factors, such as the escape of odors, dust, andairborne emissions, and can limit disease vectors.

deed restriction a notation on a property’s deed or title placing limits and conditionson the use and conveyance of the property.

design storm event a storm of an intensity, volume, and duration predicted to recur oncein a given number of years, whose effects you are designing a systemor structure to withstand. (See 24-hour, 25-year storm event.)

destructive testing the removal of a sample from a liner seam or sheet to perform tests toassess quality.

dilution/attenuation DAFs are used to measure the difference in the concentration of waste factor (DAF) constituents found in the leachate released from a waste management

unit at the source and the same leachate subsequently arriving at areceptor well. DAF is defined as the ratio of the leachate concentrationat the source to the receptor well concentration.

direct-push sampling a method of sampling ground water by hydraulically pressing and/orvibrating a probe to the desired depth and retrieving a ground-watersample through the probe. The probe is removed for reuse after thedesired volume of ground water is extracted.

diversion dike a raised land feature built to channel or control the flow of run-on andrunoff water around and within a waste management unit.

downgradient well a ground-water monitoring installation built to detect contaminantplumes from a waste management unit. In the absence of specific staterequirements, monitoring points should be no more than 150 metersdowngradient from your waste management unit boundary and placedin potential contamination migration pathways.

drainage layer in a final cover system, a stratum that directs infiltrating water todrainage systems at the toe of the cover. The drainage layer can beplaced below the surface or protection layer, but above the barrierlayer.

electrical conductivity the ability of a sample to carry an electrical charge. Used in land (EC) application to estimate the total dissolved solids content of a soil or waste.

emergency response procedures to address major types of waste management unit plan emergencies: accidents, spills, and fires/explosions.

GGlloossssaarryy

Glossary (cont.)

G-6

environmental justice the practice of identifying and addressing, as appropriate, dispropor-tionately high and adverse human health or environmental effects ofwaste manage ment programs, policies, and activities on minority andlow-income populations.

environmental stress imperfections or failures in a liner caused by environmental factors cracks before the liner is stressed to its stated maximum strength.

EPA’s Composite EPACMTP is a ground-water fate and transport model. It simulates Model for Leachate subsurface fate and transport of contaminants leaching from the Migration with bottom of a waste management unit and predicts concentrations of Transformation those contaminants in a downstream receptor as well.Products (EPACMTP)

erosion layer (see surface layer.)

expansive soils soils that lose their ability to support a foundation when subjected tocertain natural events, such as heavy rain, or human-caused events,such as explosions.

fate and transport a methodology which examines numerous waste and site characteris-modeling tics to determine how waste constituents move through the environ-

ment, how they are degraded or changed, and where they end up.

fault a failure that occurs in a geologic material, such as rock, when tectonic,volcanic, or other stresses exceed the material’s ability to withstand them.

field study in land application, a scientific investigation of waste, soil, and plantinteraction conducted under natural environmental conditions.(Compare to greenhouse study.)

filter pack in a ground-water monitoring well, a quantity of chemically inertmaterial such as quartz sand, that prevents material from surroundinggeological formations from entering the well intake and helps stabilizethe adjacent formation. Might be necessary in boreholes that are over-sized with regard to the casing and well intake diameter.

final cover a system of multiple layers of soil; engineered controls, such as liners; and/or other materials placed atop a closed waste management unit. Typicallyimproves aesthetics, prevents erosion, blocks roots and burrowing animals,collects and drains incoming water, provides a barrier between waste andthe environment, and collects gas generated within the unit.

financial assurance a funding instrument, such as a bond or trust, that provides or mechanism guarantees sufficient financial resources for the closure and post-clo-

sure care of a unit in the event the owner or operator is unable to pay.

GGlloossssaarryy

Glossary (cont.)

G-7

fines silt and clay-sized particles.

100-year floodplain a relatively flat, lowland area adjoining inland and coastal waters thatis susceptible to inundation during a 100-year flood. A 100-year floodis a large magnitude occurrence with a 1 percent chance of recurringin any given year.

foundation/gas in a final cover system, a stratum of permeable material such as sand collection layer or gravel that controls the migration of gases to collection vents and

supports overlying strata.

freeboard depth (capacity) intended to remain unused above the expected highestliquid level in a liquid storage facility, such as a surface impoundment.

freeze-thaw cycles climatic changes in which water enters a small crack in a material,expands upon freezing, and thereby expands the crack; the processthen repeats itself and the crack progressively grows. It can increasethe hydraulic conductivity of low permeability soil layers or damagegeomembranes in final covers.

fugitive dust solid particulate matter, excluding particulate matter emitted fromexhaust stacks, that become airborne directly or indirectly as a resultof human activity.

fugitive emission dust suppression at a waste management unit through measures such control as watering or chemical dust suppression.

gabion a structure formed from crushed rock encased in wire mesh and usedto check erosion and sediment transport.

gas migration the lateral and/or vertical movement of gas through a waste managementunit or its cover systems; can convey methane or other dangerous gasesto other sites or buildings if gas monitoring is not implemented.

geogrid plastic material manufactured into an open, lattice-like sheet configu-ration and typically used as reinforcement; designed with apertures oropenings sized to allow strike through of surrounding rock and soil.

geomembrane a synthetic sheet composed of one or more plastic polymers with ingre-dients such as carbon black, pigments, fillers, plasticizers, processingaids, crosslinking chemicals, anti-degradants, and biocides.Geomembranes are used as hydraulic barriers in liner and cover systems.

geophysical measurement of changes in the geophysical characteristics of monitoring subsurface soils, and in some cases, in the ground water itself, to

determine potential changes in ground-water quality.

GGlloossssaarryy

Glossary (cont.)

G-8

geosynthetic clay a factory-manufactured, hydraulic barrier typically consisting of liner (GCLs) bentonite clay (or other very low permeability materials), supported by

geotextiles and/or geomembranes held together by needling, stitching,or chemical adhesives.

geotextile a woven, nonwoven, or knitted synthetic fabric used as a filter to pre-vent the passing of fine-grained material such as silt or clay. A geotex-tile can be placed on top of a drainage layer to prevent the layer frombecoming clogged with fine material.

gravel soil particles unable to pass through the openings of a U.S. Number 4sieve, which has 4.76 mm (0.2 in.) openings.

greenhouse study in land application, a scientific investigation of waste, soil, and plantinteraction conducted under controlled indoor conditions. (Compareto field study.)

ground-water a borehole in soil outfitted with components typically including a monitoring well casing, an intake, a filter pack, and annular and surface seals; used to

collect ground water from one or more soil layers for sampling andanalysis.

ground-water The objectives of a ground-water monitoring program are to measure monitoring program the effectiveness of a waste management unit’s design; to detect changes,

or the lack thereof, in the quality of ground water caused by the pres-ence of a waste management unit; and to provide data to accuratelydetermine the nature and extent of any contamination that might occur.

ground-water a ground-water remediation technology in which contaminated water pump-and-treat is pumped to the surface for treatment.

ground-water a scientist or engineer who has received a baccalaureate or post-specialist graduate degree in the natural sciences or engineering and has suffi-

cient training and experience in ground-water hydrology and relatedfields as demonstrated by state registration, professional certifications,or completion of accredited university programs that enable that indi-vidual to make sound professional judgements regarding ground-watermonitoring, contaminant fate and transport, and corrective action.

health-based number a concentration limit for a waste constituent. The HBN is derived from(HBN) reference doses or reference concentrations that estimate the maximum

daily exposure to a waste constituent through a specific pathway (i.e.,ingestion) that would be without appreciable risk of deleterious effectsduring a lifetime.

hydraulic the velocity at which a fluid, such as leachate, flows through a material, conductivity such as a compacted clay liner.

GGlloossssaarryy

Glossary (cont.)

G-9

hydraulic loading in land application, the quantity of liquid or aqueous waste that can becapacity assimilated per unit area by the soil system.

hydraulic in land application, the application of waste in excess of the liquid or overloading water handling capacity of a soil; can result in ponding, anaerobic

waste degradation, and odors.

hydrogeologic study and quantification of a site’s subsurface features to determinecharacterization ground-water flow rate and direction; necessary for an effective

ground-water monitoring program.

Hydrologic an EPA model that evaluates the relative performance of various finalEvaluation of Landfill cover designs, estimates the flow of water across and through a final Performance (HELP) cover, and determines leachate generation rates.

infiltration the entry of precipitation, ground water, waste, or other liquid into asoil layer or other stratum.

in-situ soil geological material already present at a site; known as an in-situ linerwhen used as a barrier layer in place of imported soil or syntheticmaterials.

institutional control a measure that can be used by responsible parties and regulatory agen-cies to prevent use of or access to a site in a remedial program where,as part of the program, certain levels of contamination will remain onsite in the soil or ground water. Can also be considered in situationswhere there is an immediate threat to human health; can include deedrestrictions, restrictive covenants, use restrictions, access controls,notices, registry act requirements, transfer act requirements, and con-tractual obligations.

interfacial shear the friction or stress between components, such as a compacted clayliner and a geomembrane, that occurs on side slopes of waste manage-ment units. When the interfacial shear is inadequate, a weak plane canform on which sliding can occur. The shift in components can com-promise liner and cover performance, negatively affecting unit stability.

interim measure in corrective action, a step taken to control or abate ongoing risksbefore final remedy selection.

internal shear a stress that can lead to tearing of liner or cover components whenoverlying or underlying pressure upon a liner or cover exceeds its abil-ity to withstand this stress.

ISO 14000 voluntary set of standards for good environmental practices developed procedures by the International Standards Organization (ISO), also known as

Environmental Management Standards (EMS).

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karst terrain areas containing soluble bedrock, such as limestone or dolomite, thathave been dissolved and eroded by water, leaving characteristic phys-iographic features including sinkholes, sinking streams, caves, largesprings, and blind valleys.

land application (see land application unit.)

land application unit a waste management unit in which waste (such as sludge or waste-water) is spread onto or incorporated into the land to amend the soiland/or treat or dispose of the waste.

landfills a waste management unit in which waste is compacted in engineeredcells for permanent disposal, usually covered daily.

leachate liquid (usually water) that has percolated through waste and takensome of the waste or its constituents into solution.

leachate the concentration (usually in mg/L) of a particular waste constituent in concentration the leachate.

leachate collection a system of porous media, pipes, and pumps that collect and convey and removal system leachate out of a unit and/or control the depth of leachate above a liner.

leachate testing used to characterize waste constituents and their concentrations, andto estimate the potential amount and/or rate of the release of wasteconstituents under worst case environmental conditions.

leak detection also known as a secondary leachate collection and removal system; asystem (LDS) redundant leachate collection and removal system to detect and cap-

ture leachate that escapes or bypasses the primary system. Suddenincreases in leachate captured by an LDS can indicate failure of a pri-mary leachate collection and removal system.

lifts layers of compacted natural mineral materials (natural soils), ben-tonite-soil blends, and other materials that compose a liner or othercompacted stratum.

liner a hydraulic barrier, such as compacted clay or a geomembrane, used torestrict the downward or lateral escape of waste, waste constituents,and leachate. Liners accomplish this by physically impeding the flowof leachate and/or by adsorbing or attenuating pollutants.

in-situ soil geological material already present at a site; known as an in-situ linerwhen used as a barrier layer in place of imported soil or syntheticmaterials.

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single liner a hydraulic barrier consisting of one soil layer, one geomembrane, orany other individual barrier without a second barrier to impede conta-minants that might breach it.

composite liner a liner consisting of both a geomembrane and a compacted clay layer(or a geosynthetic clay liner).

double liner a hydraulic barrier between a waste management unit and the naturalenvironment, consisting of primary (top) and secondary (bottom) lev-els. Each level can consist of compacted clay, a geomembrane, or acomposite (consisting of a geomembrane and a compacted clay layeror GCL).

liquefaction occurs when vibrating motions caused by an earthquake turn saturatedsand grains in the soil into a viscous fluid, diminishing the bearingcapacity of the soil and possibly leading to foundation and slope fail-ures.

lithology the description of geological materials on the basis of their physicaland chemical characteristics.

lower explosive the minimum percentage of a gas by volume in the air that is necessary limit (LEL) for an explosion. This level is 5 percent for methane.

lysimeter a device used to measure the quantity or rate of water movementthrough or from a block of soil or other material. It collects soil-poreliquids by applying a vacuum that exceeds the soil moisture tension;usually a buried chamber made from wide perforated pipe.

material balances used to calculate all input and output streams, such as the annualquantities of chemicals transported to a facility and stored, used, orproduced at a facility, and released or transported from a facility as acommercial product or by-product or a waste. Material balances canassist in determining concentrations of waste constituents where ana-lytical test data are limited.

Maximum Achievable national standards that regulate major sources of hazardous air Control Technology pollutants. Each MACT standard specifies particular operations, (MACT) standards processes, and/or wastes that are covered. If a facility is covered by a

MACT standard, it must be permitted under Title V.

maximum the maximum permissible level of a contaminant in water delivered to contaminant level any user of a public water system.(MCL)

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molding water for natural soils, the degree of saturation of the soil liner at the time of content compaction; influences the engineering properties, such as hydraulic

conductivity, of the compacted material.

Monte Carlo analysis an iterative process involving the random selection of model parametervalues from specified frequency distributions, followed by simulationof the system and output of predicted values. The distribution of theoutput values can be used to determine the probability of occurrenceof any particular value given the uncertainty in the parameters. In thisguidance, used to predict a statistical distribution of exposures andrisks for a given site.

National Ambient Air airborne emission limits set by EPA as authorized by the Clean Air Act.Quality Standards EPA has designated NAAQS for the following criteria pollutants: (NAAQS) ozone, sulfur dioxide, nitrogen dioxide, lead, particulate matter, and

carbon monoxide.

National Emission national standards regulating 188 hazardous air pollutants listed inStandards for Section 112(b) of the Clean Air Act Amendments of 1990.Hazardous Air Pollutants (NESHAP)

numeric clean-up a state corrective action requirement mandating that a site be cleaned standard up such that concentrations of a waste constituent do not exceed a set

level.

operating plan a document that specifies methods of running a waste managementunit, such as standard waste-handling practices, management andmaintenance activities, employee training, and emergency plans; basedon comprehensive knowledge of the chemical and physical composi-tion of the waste managed, unit type, operational schedules, and mon-itoring performed at the unit.

overland flow land application of liquid waste by irrigation methods; can lead to (“flood”) application increased surface runoff of waste if not properly managed and, there-

fore, is regulated by some states and localities.

parametric analysis a method of statistical analysis that attempts to determine whether of variance (ANOVA) different monitoring wells have significantly different average con-

stituent concentrations.

particulate matter a mixture of solid particles and liquid droplets suspended in the (PM) atmosphere that can cause a variety of respiratory problems, carry

adsorbed pollutants far from their source, impair visibility, and stain ordamage surfaces, such as buildings or clothes, on which it settles.

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passive gas control a gas control system using natural pressure and convection system mechanisms to control gas migration and to help vent gas emissions

into the atmosphere; can include ditches; trenches; vent walls; perfo-rated pipes surrounded by coarse soil; synthetic membranes; and highmoisture, fine-grained soil.

pathogens potentially disease-causing microorganisms, such as bacteria, viruses,protozoa, and the eggs of parasitic worms.

peak flow period the phase of a storm event when flood waters are at their highest level.

pH A measure of acidity or alkalinity equal to the logarithm of the recipro-cal of hydrogen ion (H+) concentration in a medium. pH is represent-ed on a scale of 0 to 14; 7 represents a neutral state, 0 represents themost acid, and 14 the most alkaline.

pH adjustment the neutralization of acids and bases (alkaline substances) and promo-tion of the formation of precipitates, which can subsequently beremoved by conventional settling techniques.

piezometer a well installed to monitor hydraulic head of ground water or to moni-tor ground-water quality.

pilot-scale a small study to evaluate the effectiveness of and determine the treatability study potential for continued development of one or more potential reme-

dies; typically conducted to generate information on quantitative per-formance, cost, and design issues.

plasticity parameters describing a material’s ability to behave as a moldable characteristics material.

plume an elongated and mobile column or band of a contaminant movingthrough the subsurface.

point of monitoring the location(s) where ground-water is sampled; should be appropriatefor site conditions and located at waste management boundary or outto 150 meters downgradient of the waste management unit area.

post-closure care monitoring of a closed waste management unit to verify and documentthat unacceptable releases from the unit are not occurring. The overallgoal is to ensure that waste constituents are contained until such timeas containment is no longer necessary.

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prediction intervals a statistical method of approximating future sample values from a pop-ulation or distribution with a specific probability; used with ground-water monitoring data, both for comparison of downgradient wells toupgradient wells (interwell comparison) and for comparison of currentwell data to previous data for the same well (intrawell comparison).

process knowledge an understanding of industrial processes used to predict the types ofwaste generated and to determine the mechanism by which they aregenerated.

protection layer a stratum in a final cover system that protects the drainage layer fromintrusion by plant roots or burrowing animals; located below the sur-face layer and above the drainage layer.

public involvement dialogue between facility owners and operators and public to shareinformation, identify and address issues and concerns, and provideinput into the decision-making process.

public notice a document, announcement, or information release that publicizes ameeting, decision, operational change, or other information of interestto the public; usually provides the name and address of the facilityowner and operator and information about the issue being publicized.

puncture resistance the degree to which a material, such a liner, will resist rupture byjagged or angular materials which might be placed above or below it.

quality assurance in ground-water sampling, steps for collection and handling of and quality control ground-water samples to ensure accurate results. In liner construction, (QA/QC) procedures steps to ensure that liners are installed according to design and will

perform specifications.

rational method a method for calculating the volume of storm water runoff. The ratio-nal method approximates the surface water discharge from a watershedusing a runoff coefficient, the rainfall intensity, and the drainage area.

receptor a person or other organism that might be exposed to waste con-stituents, especially an organism whose exposure is addressed by a fateand transport analysis; or, a downgradient ground-water monitoringwell that receives ground water which has passed near a waste man-agement unit.

recycling the process of collecting, processing, and reusing waste materials.

redox (oxidation- the capacity of a medium to raise the valence state of molecules (such reduction) potential as metals), add oxygen, or remove hydrogen (oxidation); or to lower the

valence state of molecules, remove oxygen, or add hydrogen (reduction).

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riprap rock cover used to protect soil in dikes or channels from erosion.

risk-based corrective an approach to corrective action that integrates the components ofaction (RBCA) traditional corrective action with alternative risk and exposure assess-

ment practices. States and ASTM have developed RBCA as a threestage process.

runoff storm water that flows from a waste management unit to surface waters.

run-on storm water that falls directly on a waste management unit or flowstoward the unit from adjoining areas.

saline soil soil with excessive salt concentrations.

sampling parameters for monitoring, those items for which ground water samples will be tested,such as waste constituents reasonably expected to migrate to the groundwater and other geochemical indicators of contaminant migration.

seaming process the joining of panels or rolls of a liner using thermal, chemical, orother methods compatible with the properties of the liner material.

seismic impact zone an area having a 10 percent or greater probability that the maximumhorizontal acceleration caused by an earthquake at the site will exceed0.1g in 250 years. g is a unit of force equal to the force exerted bygravity on a body at rest and used to indicate the force to which abody is subjected when accelerated.

setback the placing of a waste management unit or one of its componentssome distance from an adjoining property, a geologic feature, or otherfeature that could affect the unit or be affected by the unit. (Compareto buffer zone.)

shear strength for soils, the internal resistance per unit area that a soil mass can offerto resist failure and sliding along any plane inside it; in liner design,indicates the degree to which stability problems and desiccation cracksare likely to occur in liner material (such as clay).

silt fence a barrier consisting of geotextile fabric supported by wooden posts;slows the flow of water and retains sediment as water filters throughthe geotextile.

slip for soils, to slide downhill in mass movements such as avalanches,land slides, and rock slides; can be caused by inherent properties ofthe soil or by cutting or filling of slopes during construction.

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slippage movement of a geomembrane liner due to a lack of adequate frictionbetween the liner and the soil subgrade or between any geosyntheticcomponents.

sodic soil soil with excessive levels of sodium ions (Na+) relative to divalent ions,such as calcium (Ca2+) and magnesium (Mg2+).

soil gas sampling collection of gas from soil pores to detect the presence or movement ofvolatile contaminants and gases, such as carbon dioxide and methane,that are associated with waste degradation.

soil-pore liquids fluids present in spaces between soil particles in the vadose zone; canbe collected to determine the type and concentration of contaminantsthat might be moving within the vadose zone.

soil water content the ratio of the weight of water to the weight of solids in a given vol-ume of soil; usually stated as a percentage and can be greater than 100percent for very soft clays.

soil water tension a measure of the strength of capillary effects holding water betweensoil particles; decreases as soil water content increases, so decreases insoil water tension beneath a lined waste management unit might indi-cate the presence of leachate due to a leaking liner.

solidification the conversion of a non-solid waste into a solid, monolithic structure processes that ideally will not permit liquids to percolate into or leach materials

out of the mass; used to immobilize waste constituents.

soluble salts materials that could dissolve in or are already in solution in yourwaste. Major soluble salts include calcium, magnesium, sodium, potas-sium, chloride, sulfate, bicarbonate, and nitrate.

Source Loading and an urban nonpoint source water quality model developed by the Management Model University of Alabama at Birmingham; useful for designing run-on and (SLAMM) runoff controls.

source reduction the prevention or reduction of waste at the point of generation.

spill prevention and procedures for avoiding accidental releases of waste or other response contaminants and promptly addressing any releases that occur.

stabilization process a means of immobilizing waste constituents by binding them into aninsoluble matrix or by changing them to insoluble forms.

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standard operating established, defined practices for the operation of a waste management procedures unit; useful in maintaining unit safety and protection of human health

and the environment; should be recorded in an operating plan to facil-itate employees’ familiarity.

storm water pipes, ditches, swales, and other structures or landforms that carry, conveyances divert, or direct run-on and/or runoff.

Storm Water EPA computer model capable of simulating the movement of Management Model precipitation and pollutants from the surface through pipe and (SWMM) channel networks, storage treatment units, and finally to surface water;

used in the design of run-on and runoff controls.

stratigraphy characterization of the origin, distribution, and succession of geologicstrata, such as soil and rock layers.

subsidence lowering of the land surface due to factors such as excessive soil load-ing, compaction of soil owing to high moisture content, or reductionin waste volume due to degradation; can significantly impair theintegrity of the final cover system by causing ponding of water on thesurface, fracturing of low permeability infiltration layers, and failure ofgeomembranes.

sump a low point in a liner system constructed to gravitationally collectleachate from either the primary or secondary leachate collection system.

surface completion the part of a ground-water monitoring well constructed at or justabove ground level, often consisting of a protective outer casingaround the inner well casing, fitted with a locking cap; discouragesvandalism and unauthorized entry into the well, prevents damage bycontact with vehicles, reduces degradation caused by direct exposureto sunlight, and prevents surface runoff from entering and infiltratingthe well.

surface a natural or manmade topographic depression, excavation, or diked impoundment area designed to hold liquid waste.

surface layer in a final cover system, a stratum that promotes the growth of native,nonwoody plant species, minimizes erosion, restores the aesthetics ofthe site, and protects the barrier layer.

surface seal neat cement or concrete surrounding a ground-water monitoring wellcasing and filling the space between the casing and the borehole at thesurface; protects against infiltration of surface water and potential con-taminants from the ground surface.

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synthetic organic man-made carbon compounds used in a variety of industrial and molecules agricultural processes, sometimes hazardous, and unlike biodegradable

organic matter, not necessarily biodegradable, or if biodegradable, notnecessarily broken down into nonhazardous byproducts.

Synthetic The SPLP is currently used by several state agencies to evaluate the Precipitation leaching of TC hazardous constituents from wastes and can be used to Leaching Procedure assess the risks posed by wastes placed in a landfill and subject to acid (SPLP) rain. The SPLP is designed to determine the mobility of both organic

and inorganic analytes present in liquids, soils, and wastes.

tear resistance the ability of a material, such as a geomembrane, to resist being splitdue to stresses at installation, high winds, or handling.

tensile behavior the tendency of a material to elongate under strain.

tensiometer an instrument that measures soil water tension.

terraces and benches earthen embankments with flat tops or ridges and channels; used tohold moisture and minimize sediment loadings in runoff.

test pad in liner design, a small-scale replica of a liner system used to verifythat the materials and methods tested will yield a liner that providesthe desired hydraulic conductivity.

thermal seaming the use of heat to join panels or rolls of a liner.

Title V operating established by the Clean Air Act, these permits are required for any permits facility emitting or having the potential to emit more than 100 tons per

year of any air pollutants, as defined by Section 302(g) of the CleanAir Act. Permits are also required for all sources subject to MACT orNSPS standards.

toe the lower endpoint of a slope.

tolerance interval a statistical interval constructed from data designed to contain a por-tion of a population, such as 95 percent of all sample measurements;used to compare data from a downgradient well to data from anupgradient well.

topography the physical features (configuration) of a surface area including relativeelevations and the position of natural and constructed features.

total dissolved solids the sum of all ions in solution.(TDS)

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total solids content the sum of suspended and dissolved solids in a liquid waste, usuallyexpressed as a percentage.

Toxicity The TCLP is most commonly used by EPA and state agencies to Characteristic evaluate the leaching potential of wastes, and to determine toxicity. Leaching Procedure The TCLP quantifies the extractability of certain hazardous (TCLP) constituents from solid waste under a defined set of laboratory condi-

tions. It evaluates the leaching of metals, volatile and semi-volatileorganic compounds, and pesticides from wastes.

ultraviolet resistance the degree to which a material, such as a geomembrane, can resist degra-dation and cracking from prolonged exposure to ultraviolet radiation.

unstable area a location susceptible to human-caused or natural events or forces,such as earthquakes, capable of impairing the integrity of a waste man-agement unit.

upgradient well a ground-water monitoring installation built to measure backgroundlevels of contamination in ground water at an elevation before itencounters a waste management unit.

upper explosive the maximum percentage of a gas by volume in the air that will permit limit an explosion. This level is 15 percent for methane; at higher percent-

ages, non- explosive burning is still possible.

use restrictions stipulations describing appropriate and inappropriate future uses of aclosed site, in an effort to perpetuate the benefits of the remedialaction and ensure property use that is consistent with the appliedclean-up standard.

vadose zone the soil (or other strata) between the ground surface and the saturatedzone; depending on climate, soils, and geology, can be very shallow oras deep as several hundred feet.

vegetative cover layer (see surface layer.)

volatile organic carbon compounds which tend to evaporate at low to moderate compounds (VOCs) temperatures due to their low vapor pressure.

waste pile a noncontainerized accumulation of solid, nonflowing waste that isused for treatment or storage.

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waste reduction waste reduction practices include source reduction, recycling and reuse,and treatment of waste constituents. Waste reduction minimizes theamount of waste that needs to be disposed of in the first place, and lim-its the environmental impact of those wastes that actually are disposed.

water content (see soil water content.)

well casing in a ground-water monitoring well, the pipe or tube lowered into theborehole as the outer wall of the well; supports the sides of the holeand prevents water from entering or leaving the well other than bynormal ground-water flow.

well intake a perforated segment of a ground-water monitoring well designed to (well screen) allow ground water to flow freely into the well from an adjacent geo-

logical formation while minimizing or eliminating the entrance of fine-grained materials such as clay or sand.

well purging procedures for removing stagnant water from a ground-water monitoring methods well and its filter pack before collecting a sample; employed to ensure

collection of samples that accurately represent current ground-waterquality.

wellhead protection the most easily contaminated zone surrounding a wellhead; officially area (WHPA) designated for protection in many jurisdictions to prevent public

drinking water sources from becoming contaminated.

wetlands areas, such as tidal zones, marshes, and bottomland forests, that areinundated or saturated by surface or ground water at a frequency orduration sufficient to support, and that under normal circumstancesdo support, a prevalence of vegetation typically adapted for life in sat-urated soil conditions.

working face the area of a waste management unit, especially a landfill, where wasteis currently being placed and compacted.

zoning local government classification of land into areas designated for differ-ent use categories, such as residential, commercial, industrial, or agri-cultural; used to protect public health and safety, maintain propertyvalues, and manage development.

Glossary (cont.)

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