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11798 Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990 /,Rules and Regulations

ENVIRONMENTAL PROTECTIONAGENCY

40 CFR Parts 261, 264, 265, 268, 271,and 302[SWH-FRL-3601-1; EPA/OSW-FR-89-0261

RIN 2050-AA78

Hazardous Waste ManagementSystem; Identification and Listing ofHazardous Waste; ToxicityCharacteristics Revisions

AGENCY: Environmental ProtectionAgency.ACTION: Final rule.

SUMMARY: On June 13, 1986, theEnvironmental Protection Agency (EPA)proposed to revise the existing toxicitycharacteristics, which are used toidentify those wastes defined ashazardous and which are subject toregulation under subtitle C of theResource Conservation and RecoveryAct (RCRA) due to their potential toleach significant concentrations ofspecific toxic constituents. The proposedrule was designed to refine and broadenthe scope of the hazardous wasteregulatory program and to fulfill specificstatutory mandates under theHazardous and Solid WasteAmendments of 1984 (HSWA).

EPA is today promulgating theToxicity Characteristics (TC]. Today'srule retains many of the features of theoriginal proposal: It replaces theExtraction Procedure (EP) leach testwith the Toxicity CharacteristicLeaching Procedure (TCLP); it adds 25organic chemicals to the list of toxicconstituents of concern; and itestablishes regulatory levels.for theseorganic chemicals based on health-based concentration thresholds and adilution/attenuation factor that wasdeveloped using a subsurface fate andtransport model. In response tocomments received on the proposed ruleand related notices, the final ruleincorporates a number of modificationsin the leaching procedure, the list oftoxicants, the chronic toxicity referencelevels, and the fate and transport model.

The overall effect of today's actionwill be to subject additional wastes toregulatory control under subtitle C ofRCRA, thereby providing for furtherprotection of human health and theenvironment.DATES: Effective Date: September 25,1990.

Compliance Dates: Large quantitygenerators: September 25, 1990. Smallquantity generators (SQGs): March 29,1991. Any person that would like to usethe Toxicity Characteristic Leaching

Procedure (TCLP} before the effectivedate may do so in order to determinewhether the eight heavy metals and sixpesticides that are currently regulatedunder the Extraction Procedure (EP)Toxicity Characteristic leach at levels ofregulatory concern.

ADDRESSES: The official record for thisrulemaking (Docket Number F---TCF-FFFFF) is located in the EPA RCRADocket (Second Floor, Rm 2427). U.S.Environmental Protection Agency, 401 MStreet SW., Washington, DC 20460. Thedocket is open from 9:00 a.m. to 4:00p.m., Monday through Friday, excludingfederal holidays. The public must makean appointment to review docketmaterials by calling (202) 475-9327. Thepublic may copy material at a cost of$0.15 per page.

FOR FURTHER INFORMATION CONTACT:.For general information about thisrulemaking, contact the RCRA/Superfund Hotline at (800) 424-9348 (tollfree) or (202) 382-3000 in theWashington, DC metropolitan area. Forinformation on specific aspects of thisrule, contact Steve Cochran, Office ofSolid Waste (OS-332), U.S.Environmental Protection Agency, 401 MStreet SW., Washington, DC 20460, (202)475-8551.

SUPPLEMENTARY INFORMATION

Preamble Outline1. AuthorityU. Background

A. Definition of Hazardous WasteB. Existing Extraction Procedure Toxicity

CharacteristicC. The Hazardous and Solid Waste

Amendments of 1984D. Previous Federal Register NoticesE. Other Notices Relating to the ProposalF. Pollution PreventionC. Summary of Final Rule

ill. Response to Major Comments andAnalysis of Issues

A. General Approach1. Expanded Use of Hazardous Waste

Characteristics2. Mismanagement Scenarioa. Extent to Which Scenario is Reasonableb. Worst-Case Scenario Selectionc. Extent to Which the Mismanagement

Scenario for Wastes Managed in SurfaceImpoundments is Appropriate

3. Targeted Risks4. Accuracy5. Solvent OverrideB. Constituents of Concern1. Final List of Constituents2. Toxicants Versus Indicator Parameters3. Method for Selecting Constituents4. Specific Organic Constituentsa. Vinyl Chlorideb. Bis(2-chloroethyl) Etherc. Toxaphened. Phenole. Pentachlorophenol

5. Specific Inorganic Constituentsa. Silverb. Chromiumc. Nickel and ThalliumC. Chronic Toxicity Reference Levels1. Maximum Contaminant Levels2. Risk-Specific Doses for Carcinogenic

Constituents3. Apportionment of Health LimitsD. Use of Generic Dilution/Attenuation

Factors (DAFs). Application of a Subsurface Fate andTransport Model

1. Introductiona. June 13. 1986, Proposed Rule (51 FR

21648)b. August 1, 1988, Notice of Data

Availability and Request for Comments;Supplement to Proposed Rule (52 FR28892)

2. Modifications of the Subsurface Fate andTransport Model (EPASMOD) inResponse to Comments

a. General Modificationsi. Unsaturated Zoneii. Source Characterizationiii. Treatment of Dilution from Rechargeiv. Location of the Receptor Wellv. Dispersivity Valuesvi. Hydraulic Conductivityvii. Hydrolysisviii. Steady-State Assumptionix. Biodegradationx. Summary of General Modificationsb. Use of the EPACML for Surface

Impoundments3. Newly Acquired Dataa. Landfill Datab. Chemical-Specific Parameters4. DAF Evaluationa. Selection of an Appropriate Percentileb. Resulting DAFs for Landfillsc. Resulting DAFs for Surface

Impoundmentsd. Final DAF SelectionF. Toxicity Characteristic Leaching

Procedure ITCLP) (Method 1311)1. Introduction2. Adoption in the LDR Rulemaking and

Modification from the Proposed Rule3. Applicability of TCLP to Solidified

Waste4. Analytical MethodsG. Testing and Recordkeeping

Requirements1. Existing Requirements for Generators2. Changes ConsideredH. Applicability to Wastes Managed in

Surface Impoundments1. Sampling Point2. Multiple Surface ImpoundmentsI. Relationship to Other RCRA Regulations1. Hazardous Waste Identification

Regulationsa. Hazardous Waste Listingsb. "Mixture" and "Derived From" Rulesc. Mixture Rule Exemptiond. Delisting2. Land Disposal Restrictionsa. Risk Levels and Frequency Intervalb. Treatment Standards for TC Wastesc. Schedule for LDR Determinations3. RCRA Corrective Action and Closure

Requirements'4. Minimum Technology Requirements

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Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

a. Applicabilityb. Scope of Minimum Technology

Requirements1. Permitted Facilities2. Interim Status Facilitiesc. Compliance with Minimum Technology

Requirements5. RCRA Subtitle D (Solid Wastes)a. Municipal Waste Combustion Ashb. Impact on Wastes Excluded from

Subtitle C Regulation6. RCRA Subtitle I (Underground Storage

Tanks)a. Scope of the Underground Storage TankProgram

b. Deferral for Petroleum-ContaminatedMedia and Debris Subject to Part 280Corrective Action Requirements

7. RCRA Section 3004(n) Air RegulationsJ. Relationship to Other Regulatory

Authorities1. Comprehensive Environmental

Response, Compensation, and LiabilityAct (CERCLA).

2. Clean Water Acta. Conflict with NPDES Effluent Guidelines

and Pretreatment Standardsb. Permit Requirements for Wastewater

Treatment Facilitiesc. Sludges from Publicly Owned Treatment

Works (POTW)3. Safe Drinking Water Act4. Federal Insecticide, Fungicide, and

Rodenticide Act (FIFRA)a. Pesticide Wastesb. Treated Wood Wastes5. Food. Drug, and Cosmetic Act (FDCA)a. Food Wastesb. Pharmaceutical and Cosmetic Wastes6. Used Oil Recycling Act7. Toxic Substances Control Act (TSCA)K. Implementation Issues1. Notification2. Effective Date3. Permitting

IV. Regulatory LevelsA. List of Constituents1. Proposed List2. Constituents for Which Final Regulatory

Levels Are Not Now Being Promulgated3. Final List of Constituentsa. Organic Constituentsb. Inorganic ConstituentsB. Selection of DAFsC. Analytical ConstraintsD. Final Regulatory Levels

V. ImplementationA. State Authority1. Applicability of Final Rule in Authorized

States2. Effect on State AuthorizationB. Integration of Today's Final Rule with

Existing EPTC1. Facilities Located in Authorized States2. Facilities Located in Unauthorized StatesC. NotificationD. PermittingE. Compliance Date

VI. Regulatory RequirementsA. IntroductionB. Regulatory Impact Analysis1. Executive Order No. 122912. Basic Approach3. Methodologya. Determination of Affected Wastes and

Facilities

b. Cost Methodology1. Social Costs2. Compliance Costsc. Economic Impact Methodologyd. Benefits Methodology1. Human Health Risk Reduction2. Resource Damage Avoided3. Cleanup Costs Avoidede. Used Oil Methodology4. Resultsa. Affected Wastes and Facilities1. Affected Wastes2. Affected Facilities3. Sensitivity Analysis of Affected Wastes

and Facilitiesb. Cost Results1. Social Costs and Compliance Costs2. Sensitivity Analysis of Costsc. Economic Impact Results1. Significantly Affected Facilities2. Effects on Product and Capital Markets3. Sensitivity Analysis of Economic

Impactsd. Benefits Results1. MEI Risk2. Population Risk3. Resource Damage4. Cleanup Costs Avoided5. Sensitivity Analysis of Benefitse. Cost Effectivenessf. Used Oil ResultsC. Regulatory Flexibility Analysis1. Approach2. ResultsD. Response to Comments on RIA for June

13, 1986, Proposal1. Industries Included in the Analysis2. Estimation of Costs and Economic

Impacts3. Estimation of Benefits4. Cost-Benefit Comparisons5. Small Business AnalysisE. Paperwork Reduction Act

VII. References

I. Authority

The amendments to the hazardouswaste regulations in 40 CFR parts 261and 271 are being promulgated under theauthority of sections 1006, 2002(a), 3001,3002, and 3006 of the Solid WasteDisposal Act of 1970, as amended by theResource Conservation and RecoveryAct of 1976, as amended (42 U.S.C. 6905,6912(a), 6921, 6922, and 6926). Theamendments to the list of hazardoussubstances and reportable quantities in40 CFR part 302 are being promulgatedunder the authority of section 102 of theComprehensive EnvironmentalResponse, Compensation, and LiabilityAct of 1980 (42 U.S.C. 9602), asamended, and sections 311 and 501(a) ofthe Federal Water Pollution Control Act(33 U.S.C. 1321 and 1361).

II. Background

A. Definition of Hazardous Waste

Subtitle C of the ResourceConservation and Recovery Act(RCRA), as amended, establishes afederal program for the comprehensiveregulation of hazardous waste Section

1004(5) of RCRA defines hazardouswaste, among other things, as solidwaste that may ". . . pose a substantialpresent or potential hazard to humanhealth and the environment whenimproperly treated, stored, transported,disposed, or otherwise managed." UnderRCRA Section 3001, EPA is charged withdefining which solid wastes arehazardous by either identifying thecharacteristics of hazardous waste orlisting particular hazardous wastes.Identifying characteristics of hazardouswaste and listing hazardous wastes aredistinct and fundamentally differentmechanisms for defining hazardouswastes.

The hazardous waste characteristicspromulgated by EPA designate broadclasses of wastes which are clearlyhazardous by virtue of an inherentproperty. In the May 19, 1980 final rule(45 FR 33084) that instituted EPA'sgeneral framework for identifyinghazardous waste,'the Agencyestablished two basic criteria foridentifying hazardous wastecharacteristics: (1) The characteristicshould be capable of being defined interms of physical, chemical, or otherproperties which cause the waste tomeet the statutory definition ofhazardous waste; and (2) the propertiesdefining the characteristic must bemeasurable by standardized andavailable testing protocols orreasonably detected by generatorsthrough their knowledge of the waste (40CFR 261.10). In the May 19, 1980 finalrule, EPA stated that it adopted thesecond criterion in recognition that theprimary responsibility for determiningwhether wastes exhibit hazardouscharacteristics rests with generators, forwhom standardization and availabilityof testing protocols are essential.

The approach EPA uses to establishhazardous waste characteristics is todetermine which properties of a wastewould result in harm to human health orthe enviromnent if a waste ismismanaged. The Agency thenestablishes test methods and regulatorylevels for each characteristic property;solid waste that exceeds the regulatorylevel for any characteristic property is ahazardous waste.

The regulatory levels forcharacteristics that have beenestablished provide a high degree ofcertainty that wastes exceeding thoseregulatory levels would pose hazards tohuman health and the environment ifimproperly managed and thereforerequire regulation under subtitle C.Wastes that do not exhibit hazardouswaste characteristics are not necessarilynonhazardous. The Agency may

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11800 Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

evaluate wastes from either specific ornonspecific sources and decide to listthem as hazardous wastes based oncriteria defined in 40 CFR 261.11.

To list a waste as hazardous, EPAconducts a detailed industry or processstudy involving literature reviews,engineering analyses, surveys andquestionnaires, site visits, and wastesampling. For listing, the Agency placesparticular emphasis on hazardousconstituents contained in specificwastes generated by the industry orprocess being studied (See 40 CFR261.11(a)(3)). However, EPA uses acomparatively flexible approach whendeciding to list wastes as hazardous; theapproach includes consideration offactors such as type of threat posed,plausible ways that the waste might bemismanaged, migration potential andpersistence in the environment, wastequantity, and actions of other regulatoryprograms. The Agency also promulgatedtwo other rules for identifying solidwastes as hazardous wastes-themixture and derived-from rules. Themixture rule says that any mixture of alisted hazardous waste and a solidwaste is the listed hazardous waste (40CFR 261.3(a)(2)(iii)-(iv)); the derived-from rule says that any solid wastederived from the treatment, storage, ordisposal of a listed hazardous waste isconsidered the listed hazardous waste(40 CFR 261.3(c)-(d)).

B. Existing Extraction ProcedureToxicity Characteristic

The Extraction Procedure (EP) toxicitycharacteristic is one of four existinghazardous waste characteristics (alongwith ignitability, corrosivity, andreactivity) that EPA has identified andpromulgated (40 CFR 261.24). TheExtraction Procedure ToxicityCharacteristic (EPTC) defines thetoxicity of a waste by measuring thepotential for the toxic constituents in thewaste not subject to subtitle C controlsto leach out and contaminate groundwater at levels of health orenvironmental concern. To determine ifa waste exhibits the EPTC, constituentsare extracted in a procedure thatsimulates the leaching action that occursin municipal landfills. Because a"hazardous waste" is defined as a wastethat may pose a substantial hazard"when mismanaged," the EP wasdesigned based on the assumption thatwastes not subject to subtitle C controlswould be co-disposed with municipalwaste in an actively decomposinglandfill that overlies an aquifer. Thus,the EP identifies wastes that are likelyto leach hazardous concentrations ofparticular toxic constituents to ground

water under conditions of impropermanagement.

The Agency recognized that not allwastes are managed according to themismanagement scenario postulated forthe EP. However, it is necessary to makeassumptions about managementpractices for unregulated wastes inorder to determine whether a wasteposes a threat to human health and theenvironment and thus meets thestatutory definition of hazardous waste.In addition, the Agency believed that areasonably conservativemismanagement scenario waswarranted in light of the statutorymandate to protect human health andthe environment.

Under the existing EPTC, the liquidwaste extract obtained from the EP isanalyzed to determine whether itpossesses any of 14 toxic contaminantsthat were identified in the NationalInterim Primary Drinking WaterStandards (NIPDWS): eight metals(arsenic, barium, cadmium, chromium,lead, mercury, selenium, and silver), fourinsecticides (endrin, lindane,methoxychlor, and toxaphene), and twoherbicides (2,4-D and 2,4,5-TP).NIPDWS levels are used as health-based concentration limits. At the timeof promulgation of the EPTC, theNIPDWS were the only availablebenchmarks for toxicity that werescientifically recognized and that alsoaddressed chronic exposure.

The regulatory levels established forthe EPTC were 100 times the NIPDWS.The 100-fold factor is a dilution andattenuation factor (DAF) that estimatesthe dilution and attenuation of the toxicconstituents in a waste as they travelthrough the subsurface from the point ofleachate generation (i.e., the landfill) tothe point of human or environmentalexposure (i.e., at a drinking-water well).The Agency had originally proposed aDAF of 10 for use in the EP. In light ofthe fact that there were few empiricaldata on which to base the DAF andother considerations, the Agencyadopted a DAF of 100 in the final rule(45 FR 33084, May 19, 1980). EPA wasconfident that any waste whichexhibited the EPTC using the 100-foldfactor would have the potential topresent a substantial hazard regardlessof the actual site-specific attenuationmechanisms. The Agency also notedthat it would adjust the DAF if futurestudies indicated that another DAF wasmore appropriate.C. The Hazardous and Solid WasteAmendments of 1984

On November 8, 1984, the Hazardousand Solid Waste Amendments of 1984(HSWA) were enacted: these

amendments have had far-reachingramifications for EPA's hazardous wasteregulatory program. RCRA sections 3001(g) and (h), which were among the manyprovisions added by HSWA, direct EPAto examine and revise the EP ToxicityCharacteristic and to identify additionalhazardous waste characteristics,including measures of toxicity. Today'srule fulfills these mandates bypromulgating an improved leachingprocedure that better predicts leachingand an expansion of the ToxicityCharacteristics {TC) list to includeadditional toxicants.

RCRA section 3001(g) specificallydirects EPA to examine the EP leachprocedure as a predictor of the leachingpotential of waste and to make changesnecessary to ensure that it accuratelypredicts the leaching potential of wastesthat may pose a threat to human healthand the environment when mismanaged.The legislative history for this provisionindicates that Congress was specificallyconcerned about the EP's ability toaccurately represent the mobility oftoxicants under a wide variety ofconditions. The legislative history alsosuggests that Congress intended for EPAto develop a more aggressive leachingmedium for the test and noted that theEP only evaluated the mobility ofelemental toxicants and not the mobilityof organic toxicants.

Concerned that some wastes posing athreat to human health and theenvironment were not being brought intothe hazardous waste system, Congressadopted RCRA section 3001(h), whichdirects EPA to promulgate additionalcharacteristics. Of specific concern toCongress was the fact that the existingcharacteristics did not identify wastesthat were hazardous due to toxic levelsof organic constituents. AlthoughCongress recognized that thedevelopment of such a characteristicwould entail technical problems,Congress urged the Agency to makereasonable assumptions for purposes ofregulation, rather than await definitivetechnical answers. In response to the3001(g) and 3001(h) mandates, EPAissued a proposed rule to revise andexpand the TC (51 FR 21648, June 13,1986) which is discussed below inSection II.D.

D. Previous Federal Register Notices

As indicated above, EPA published aFederal Register notice (June 13, 1986)proposing to expand the existing TC.The proposal specifically identified 52compounds that could cause a waste tobe hazardous via toxicity, including theexisting 14 EPTC compounds and 38additional organic compounds. In


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addition, it described the ToxicityCharacteristic Leaching Procedure(TCLP), a new version of the EP. TheTCLP is designed to more accuratelyaddress the leaching of organiccompounds and to improve upontechnical aspects of the testing protocol.

The June 13 proposal used asubsurface fate and transport model todetermine compound-specific dilutionand attenuation factors (DAFs) as abasis for establishing the regulatorylevels. (As mentioned above, theexisting TC used a generic DAF of 100which was not derived from modeling,but rather was an estimated factorindicating the potential for substantialhazard.) The extract from the second-generation extraction procedure, theTCLP, was analyzed for the presence ofthe 52 constituents at the proposedregulatory levels. In choosing the 38 newtoxicants, the Agency identified thoseAppendix VIII constituents for whichappropriate chronic toxicity referencelevels were available and for whichthere existed adequate fate andtransport data to establish a compound-specific DAF. (Appendix VIII of 40 CFRpart 261 is the list of hazardousconstituents that the Agency considersin evaluating the potential hazard posedby wastes; these constituents have beenshown to have toxic, carcinogenic,mutagenic, or teratogenic effects.)

Chronic toxicity reference levels arethose levels below which chronicexposure for individual toxicants indrinking water is considered safe orconsidered to pose minimal risk (in thecase of carcinogens). The Agencydecided to use, when possible, humanhealth criteria and standards that havebeen proposed or promulgated forsubstances in particular media, becausethese have already received Agency andpublic review and evaluation. EPAproposed the continued use of the

Drinking Water Standards (DWS) forthe 14 existing EP toxicants and use ofRecommended Maximum ContaminantLevels (RMCLs) for eight of theconstituents being added to the TC list.For the remaining newly addedconstituents, EPA proposed to establishchronic toxicity reference levels usingReference Doses (RfDs) for non-carcinogens and Risk-Specific Doses(RSDs) for carcinogens.

The RfD is an estimate of the dailydose of a substance that will result in noadverse effect even after a lifetime ofexposure to the substance at that dose.In order to account for toxicantexposure from sources other than water(i.e., air and food), the Agency proposedto apportion the RfD based onproportionate compound-specificexposure routes, as is done indeveloping drinking water standards.

The RSD is the daily dose of acarcinogen over a lifetime that willresult in an incidence of cancer equal toa specific risk level. EPA proposed aweight-of-evidence approach, whichinvolves categorizing carcinogensaccording to the quality and adequacyof the supporting toxicological studies,to establish the risk levels mostappropriate for setting chronic toxicityreference levels for carcinogens.

The Agency proposed using asubsurface fate and transport model tocalculate constituent-specific DAFs.This model incorporated compound-specific hydrolysis and soil adsorptiondata, coupled with parametersdescribing an underground environment(e.g., ground water flow rate, soilporosity, ground water pH). Values forparameters were selected based onreview of geological conditions atexisting landfills. Since the model wasspecifically developed to simulatetransport of organics and a model forinorganics could not be completed in

time for the June 13 proposal, EPAproposed to retain the existing EP levelsfor the eight inorganic toxicants.

The proposed rule introduced theTCLP as a second-generation leachingprocedure to replace the existing EP.The main impetus behind thedevelopment of the TCLP was the needto address the leaching of organiccompounds. However, the Agency alsorecognized that the EP protocol could beimproved in certain ways. The TCLPwas described in detail as a proposedrevision to Appendix I of part 261.Further supporting information on theTCLP was provided through notices ofavailability of reports on July 9, 1986 (51FR 24856) and September 19, 1986 (51 FR33297). After the TC proposal, the LandDisposal Restrictions final rule (51 FR40572, November 7, 1986) promulgatedthe TCLP for monitoring compliancewith treatment standards for certainspent solvent wastes and dioxin-contaminated wastes. See Section IL.Ebelow for further discussion of thesenotices.

E. Other Notices Relating to theProposal

Today's rule is based on threefundamental analytic components thatwere set forth in the original June 13proposal: a set of chronic toxicityreference levels, a subsurface fate andtransport model, and the TCLP. Inaddition to the June 13,1986 proposedrule described in the preceding sectionof this preamble, EPA has publishedseveral other notices in the FederalRegister dealing with these threecomponents. These notices are listed inTable I1.1 and are summarized in thissection. A more detailed discussion ispresented on several of these notices inother sections of this preamble, asidentified in Table 11.1.

TABLE 11.--RELATED FEDERAL REGISTER NOTICES DISCUSSING ONE OR MORE OF THE ANALYTICAL COMPONENTS OF THE REVISEDTC

Federal Register Analytic Component Relevant preambleCTRLs Model TCLP 3 section of today's rute

Jan. 14. 1986. 51 FR 1602 (Proposed LDR framework) ............................ ............. X X IIlE, I1.1Nov. 7, 1986,51 FR 40572 (Final LOR approach) .................................................................................................... X ItI.FMay 18, 1987, 52 FR 18583 (Consideration of separate wastewater TC) ......................... X X Il.A, III.HMay 19, 1988. 53 FR 18024 (CTRLs updated, two-tiered DAF alternative X X ........................ . .. IlIC. 11.1

proposed).May 24. 1988, 53 FR 18792 (Proposal to replace particle reduction) ........................... X IIFAug. 1, 1988, 53 FR 28892 (Proposed modifications to ground water ...... . ...... ........... X ................................... III.E

-model).

Cronic Toxcity Reference Levels.2 Ground water fate and transport model.8Toxiciy Characteristic Leaching Procedure.

11801This information is reproduced with permission from HeinOnline, under contract to EPA. By including this material, EPA does not endorse HeinOnline.


. EPA's first discussion of thedevelopment of regulatory levelsthrough the use of chronic toxicityreference levels in combination with asubsurface fate and transport modelwas-in the proposed rule governing landdisposal restrictions for solvents anddioxins (51 FR 1602, January 14,1986).This proposal introduced the conceptinvolved in "back-calculating"regulatory levels (i.e., multiplyingchronic toxicity reference levels bydilution/ attenuation factors) and alsodiscussed the Agency's plan for revisingthe EP. In the final rule on land disposalrestrictions for solvents and dioxins (51FR 40572, November 7, 1986), EPAdecided not to use the "back-calculationapproach" for the LDR program in favorof an engineering determination basedon the best demonstrated availabletechnology (BDAT). However, theAgency did promulgate the revisedTCLP as the leaching procedure to beused in the land disposal restrictionsprogram. Specifically, the TCLP is usedto demonstrate that certain wastes meetthe best demonstrated availabletechnology standards.

On May 18, 1987, EPA published aSupplemental Notice of ProposedRulemaking (52 FR 18583) in response tonumerous comments on the June 1986proposal concerning the application ofthe revised TC to wastewaters. Thecommenters' main concern was that itmay be inappropriate to apply the TCmismanagement scenario (co-disposal ofwastes with municipal wastes in anunlined landfill) to wastewatersmanaged in surface impoundments. Thecommenters believe that such anapproach would result ininappropriately low regulatory levels.The Supplemental Notice outlinedseveral alternatives for the applicationof the TC to wastewaters that wouldresult in a separate set of regulatorylevels for these wastes. The alternativescenario for wastewaters assumed thatsubject wastes are managed in anunlined impoundment instead of beingco-disposed in a municipal landfill.Sections III.A.2, IMl.E., and III.H providefurther discussion of the SupplementalNotice for wastewaters and relatedissues.

The Agency then published a Noticeof Data Availability and Request forComments on May 19, 1988 (53 FR18024), as a result of its concern aboutuncertainties and technical difficultiesinvolved with developing sufficientlyrepresentative dilution/attenuationfactors (DAFs) for specific constituents.In that notice, the Agency proposed analternative to the constituent-specificDAFs in the proposed TC. The Agency

presented a two-phased approach toimplementing DAFs for the TC. In thefirst phase, the Agency would usegeneric DAFs for all 38 new TC organicconstituents while the development ofconstituent-specific DAFs proceeded;once the development of the constituent-specific DAFs was completed, theseDAFs would be implemented in thesecond phase. The Agency specificallyrequested comment on the use of ageneric DAF that would initially bringinto the hazardous waste regulatorysystem the most toxic of the wastessubject to the June 1986 proposal. TheAgency also updated the chronictoxicity reference levels for a number ofconstituents based on newly availableinformation. Section III.C discusses theincorporation of the new informationinto the chronic toxicity reference levelsfor specific constituents and SectionII.D describes in more detail the two-tiered DAF approach.

In response to numerous commentsexpressing concern as to whether theparticle reduction requirement in theTCLP wa's appropriate. EPA published aproposal (53 FR 18792, May 24, 1988)requesting comment on modifications tothe TCLP as promulgated on November7, 1986. Based on further experimentalevaluation of the original testingmethodology, the Agency proposed tomodify the TCLP to include a cage insertrequirement in place of the particlereduction step for certain materials. Thespecific revisions discussed in theproposal are presented in detail insection 1M.F of this preamble, and theTCLP protocol is presented in SectionVIII of today's final rule. Today's ruledoes not include a cage requirement, butrather retains the particle reduction stepfor monolithic or fixated wastes.

In addition to the above-mentionedmodifications, on August 1, 1988, theAgency published a SupplementalNotice (53 FR 28892) introducingpotential modifications to thesubsurface fate and transport modelused to calculate constituent-specificDAFs in the proposed TC. In addition,the Agency presented currentlyavailable hydrogeological data onmunicipal waste landfills and proposedto modify the subsurface fate andtransport model to more accuratelyreflect conditions in the universe ofmunicipal waste landfills. Section III.Epresents a more detailed description ofthe subsurface fate and transport modeland the modifications made during itsdevelopment.

F. Pollution Prevention

In section 1003(b) of RCRA, Congressdeclared waste minimization to be anational policy. Similarly, EPA has

made pollution prevention an Agencyobjective, in both regulatory andnonregulatory programs. (See EPA'spolicy statement emphasizing theimportance of pollution prevention (54FR 3845, January 26,1989).) This policyplaces highest priority on sourcereduction (i.e., reducing the volume ortoxicity of wastes generated) and use ofall pollutants for all sectors of society. Areduction in the amount of waste whichmust be managed (i.e., by sourcereduction and recycling) provides directbenefits related to protecting humanhealth and the environment from themismanagement of hazardous wastes.Pollution prevention measures can alsoreduce waste treatment and disposalcosts, decrease costs for raw materials,minimize liability and regulatoryburdens for waste generators, and mayenhance efficiency, product quality, andpublic image. The Agency encouragesindustries affected by this rule toconsider achieving compliance throughpollution prevention.

The Agency has taken several steps tocreate pollution prevention incentives.First, EPA is developing institutionalstructures within each of its offices toensure that the pollution preventionphilosophy is incorporated into everyfeasible aspect of internal EPA planningand decision-making. Second, EPA ismaking tecinical information availableto help firms reduce waste generation.EPA is developing the PollutionPrevention Information Clearinghouse(PPIC), a network of people andresources throughout the United Statesthat have direct experience in manyindustries. PPIC includes the ElectronicInformation Exchange System (EIES),and a database of bulletins, programs,contacts, and reports related to pollutionprevention. Third, the Agency issupporting the development of stateprograms to assist generators in theirwaste reduction efforts. Many states arealready providing such help. Forexample, the Alaska Health Project haspublished technical assistance packetsfor specific industries; North Carolinahas a pollution prevention bibliography;and Oregon conducts a hazardous wastereduction program. Finally, EPA hasinitiated specific regulatoryiequirements addressing wasteminimization. Under the ResourceConservation and Recovery Act (RCRA)regulations, hazardous waste generatorsare required to certify on theirhazardous waste manifests and annualpermit reports that they have a programin place to reduce the volume orquantity and toxicity of their hazardouswastes as much as economicallypractical. RCRA regulations also require


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generators to describe on their RCRAbiennial reports the efforts they haveundertaken during the year to reduce thevolume and toxicity of their hazardouswaste and to compare these efforts toprevious years.

As important as the efforts just "described is the Agency's commitmentto ensuring that regulations underdevelopment encourage pollutionprevention, whenever possible. The TC(TC), we believe, provides significantincentives for pollution prevention.Curiently, there is little incentive forindustries to implement pollutionprevention efforts for unregulated solidwastes. In particular, there are fewcontrols on units handling solid wastesthat have the potential for releases ofhazardous constituents to groundwater.Large quantities of solid wastescontaining TC constituents currently aremanaged in unregulated land-basedunits, such as surface impoundmentsand landfills. Many of these units are instates that are either highly dependenton groundwater for public water supplyor where groundwater is hydraulicallyconnected to surface water, or both. Bysubjecting management of TC wastes tosubtitle C regulation, EPA is in effectrequiring that waste managers rethinktheir practices for solid wastes thatcontain hazardous constituents. EPA'sexperience has been that hazardouswaste regulations provide significantincentives for pollution prevention. Forexample, some listed wastestreams (e.g.,bottoms from tetrachloroethyleneproduction) are now completelyrecycled.

The characteristic mechanism used byEPA to identify hazardous waste isespecially effective in encouragingpollution prevention because it sets aconcentration level or criteria (e.g. test]that determines the point at which thewaste is no longer regulated ascharacteristically hazardous. Because ofthe high cost of compliance with RCRAsubtitle C requirements, members of theregulated community will havesignificant new incentives to reduce TCwaste generation as a xesult of today'srule. Industries will consider substitutesfor the specific chemicals on the TC listof toxicants of concern. Wheresubstitutes are not used, there will beincentive to reduce the use of hazardoussubstances or otherwise limit theirconcentrations in wastes, in order tokeep concentrations of hazardouschemicals below regulatory levels.

Pollution prevention options rangefrom simple good housekeepingpractices, e.g., keeping solvents and oilsseparate to facilitate recycling of each,to more extensive process

reconfigurations and/or raw material -substitutions. Even in cases wherepollution prevention can not eliminatethe need for treatment or disposal ofhazardous wastes, it may reduce thegeneration of waste. For example, tankcapacity is constrained by land area,engineering considerations, and cost.Managers of TC wastewaters thatswitch from surface impoundments toexempt tanks will almost certainly haveto reduce volumes of hazardous wastegenerated, or segregate hazardousportions of their wastestreams.

In order to enhance the pollutionpreventions effects of this rule, EPA isincorporating pollution prevention intothe communication strategy for the TCregulation. EPA will provide informationtargeted to small businesses specifically.and industry in general throughpamphlets, industry publications andconferences, on the mechanismsdescribed above. We have found'thatmany small businesses are turning topollution prevention as a result ofimplementation of the small quantitygenerator regulations (see 51 FR 10146,March 24, 1986). For example, PPICdocuments relate how one drycleaningoperation reduced its solvent wastes toa level well below national industrystandards by regularly checking for andsealing any system leaks, and installinga conditioning system and a carbonadsorption unit to recover additionalsolvent. With the new setup, the plantcan clean four times as many clothes perdrum of solvent. The Agency believesthat other industries may have thepotential to substitute less toxic sourcematerials in their processes. EPA willconsider whether any technicalassistance could aid industry in theseefforts. EPA would also be interested insuggestions from industries affected bythe TC in ways that the Agency mightfacilitate these efforts. Inquiries shouldbe directed to the Pollution PreventionOffice, U.S. EPA, Washington, DC 20460.

In summary, the TC will alter themanagement of wastes that containtoxicant at hazardous levels by endingmanagement in unregulated land-basedunits. As industries reassess their wastegeneration and management practices,many are likely to seriously considerpollution prevention options, and EPAwill take steps to facilitate such efforts.G. Summary of Final Rule

Today's rule retains many of thefeatures of the June 1986 proposal: itreplaces the EP with the TCLP; it adds25 new organic constituents to the list oftoxic constituents of concern; and itestablishes regulatory levels for theorganic constituents based on health-based concentration limits and a DAF

developed using the subsurface fate-andtransport model. In response tocomments received on the proposed ruleand related notices, the final ruleincorporates a number of modificationsto the list of constituents, the leachingprocedure, the chronic toxicity referencelevels, the subsurface fate and transportmodel, and the schedule for compliancewith the TC rule.

With respect to the list ofconstituents, the final rule includes 25 ofthe 38 constituents proposed in 1986.One group that has been excluded in thefinal rule are constituents thatappreciably hydrolyze. EPA has beenable to develop scientifically valid DAFsfor nondegrading constituents but is stillimproving its approach for developingDAFs for constituents that are expectedto hydrolyze appreciably duringtransport. In particular, the Agency doesnot yet have a procedure to addresstoxic hydrolysis byproducts that may beformed.

Second, in response to comments, theAgency has also evaluated theapplicability of the steady-statecondition assumed in the subsurfacefate and transport model, and hasdetermined that the assumption is validfor most of the originally proposedconstituents. However, several of theoriginal proposed constituents havebeen deferred from the final rule whilethe Agency continues to evaluate theextent to which the steady-state solutionis appropriate in determining their fateand transport.

As a result, all the constituents newlyregulated under today's rule arenonhydrolyzing or minimallyhydrolyzing constituents, and all areconstituents for which the steady-statesolution is appropriate. For all theseconstituents, EPA has determined,based on the results of its subsurfacefate and transport model, that use of aDAF of 100 is appropriate for settingregulatory levels. This DAF is sufficientto capture only those wastes that areclearly hazardous. As a result of theAgency's decision to regulate onlynonhydrolyzing or minimallyhydrolyzing constituents and those forwhich the steady-state solution is.appropriate, 25 additional constituentsare being regulated rather than theoriginally proposed 38. Regulatory levelsfor hydrolyzing constituents, as well asthose constituents for which thereremain questions as to whether thesteady-state solution is appropriate, willbe discussed in future notices.

The list of constituents regulated intoday's rule and their respectiveregulatory levels are presented in Table11.2. As in the proposed rule, where the



calculated regulatory level (i.e., the quantitation limit is the final regulatory EPTC. As specifiedin today's rule, thesechronic toxicity reference level level. Note that the list of constituents in constituents will continue to bemultiplied by the DAF) is below the Table 11.2 contains the 14 constituents regulated at their current levels.analytical quantitation limit, the currently regulated under the existing

TABLE 11.2.-TOXiCiTY CHARACTERISTIC CONSTITUENTS AND REGULATORY LEVELS

Chronic toxicity reference RegulatoryEPA HW No.' Constituent (rg/L) GAS No.' level (mg/L) level (mg/L)

D004 Arsenic .............................................................................................................. . ..... 7440-38-2 0.05 5.0D005 Barium ...................................................................................................................... 7440-39-3 1.0 100.0D018 Benzene ................................................................................................................. 71-43-2 0.005 0.5D006 Cadmium ................................................................................................................ 7440-43-9 0.01 1.0D019 Carbon tetrachloride ........................................................ ............................... 56-23-5 0.005 0.5D020 Chlordane ................................................................................................................ 57-74-9 0.0003 0.03D021 Chlorobenzene ......................................................................................................... 108-90-7 1 100.0D022 Chloroform ............................................................................................................. 67-66-3 0.06 6.0D007 Chromium ................................................................................................................ 7440-47-3 0.05 5.0D023 o-Cresol .................................................................................................................... 95-48-7 2 4200.0D024 m-Cresol ............................................................................................................... 108-39-4 2 4 200.0D025 p-Cresol ................................................................................................................. 106-44-5 2 4 200.0D026 Cresol .................................................................................. ..................................... ...............................i............ 2 200.0

D016 2,4-D ........... ......... ....................................... 94-75-7 0.1 10.0D027 1,4-Dichlorobenzene ......................................... .106-46-7 0.075 7.5D028 1,2-Dichloroethane .................................................................................................. 107-06-2 0.005 0.5D029 1,1-Dichloroethylene ............................................................................................... 75-35-4 0.007 0.7D030 2,4-Dinitrotoluene .................................................................................................... 121-14-2 0.0005 30.13D012 Endrin ........................................................................................................................ 72-20-8 0.0002 0.02D031 Heptachlor (and its hydroxide) ........................................................................... 76-44-8 0.00008 0.008D032 Hexachlorobenzn e .............................................................................................. 118-74-1 0.0002 3 0.13D033 Hexachloro-1,3-butadiene ..................................................................................... 87-68-3 0.005 0.5D034 Hexachloroethane .................................................................................................. 67-72-1 0.03 3.0D008 Lead ........................................................................................................................ 7439-92-1 0.05 5.0D013 Lindane .................................................................................................................... 58-89-9 0.004 0.4

D009 Mercury .................................................................................................................... 7439-97-6 0.002 0.2D014 Methoxychlor ............................................................................................................ 72-43-5 0.1 10.00035 Methyl ethyl ketone ................................................................................................ 78-93-3 2 200.00036 Nitrobenzene ............................................................................................................ 98-95-3 0.02 2.0D037 Pentachlorophenol ................................................................................................ 87-86-5 1 100.0D038 Pyridine .................................................................................................................. 110-86-1 0.04 3 5.0D010 Selenium .................................................................................................................. 7782-49 2 0.01 1.0D011 - Silver ........................................................................................................................ 7440-22-4 0.05 5.0D039 Tetrachloroethylene ................................................................................................ 127-18-4 0.007 0.7D015 Toxaphene .............................................................................................................. 8001-35-2 0.005 0.5D040 Trichloroethylene ..................................................................................................... 79-01-6 0.005 0.5D041 2,4,5-Trichlorophenol .............................................................................................. 95-95-4 4 400.0D042 2,4,6-Trichlorophenol ................................... 88-06-2 0.02 2.0D017 2,4,5-TP (Silvex) ....................................................................... ................. 93-72-1 0.01 1.0D043 Vinyl chloride ........................................................................................................ 75-01-4 0.002 0.2

'Hazardous waste number.2 Chemical abstracts service number.3 Quantitation limit is greater than the calculated regulatory level. The quantitation limit therefore becomes the regulatory level.4 If o-, m-, and p-cresol concentrations cannot be differentiated, the total cresol (D026) concentration is used. The regulatory level for total cresol is 200 mg/I.

The regulatory levels reflectmodifications to some chronic toxicityreference levels since the originalproposal. EPA has revised some of theMaximum Contaminant Levels, Risk-Specific Doses, and Reference Doses toreflect new data and better methods. Inresponse to comments received, EPAhas decided not to apportion referencedoses of noncarcinogens to account formultiple routes of exposure, as wasoriginally proposed (51 FR 21648). Seesection III.C for further discussion ofcomments on apportionment and theAgency's reasons for not includingapportionment of reference doses in thefinal rule. Today's rule also promulgatesthe TCLP to replace the EP. The TCLPrepresents an improvement over the EPin that it more accurately addresses

leaching potential for use in evaluatingwastes containing organic constituents,and also corrects several minortechnical deficiencies in the original EP.The version of the TCLP promulgatedtoday reflects additional improvementsand modifications made to the TCLPsince the original proposal. The TCLPpromulgated today will also replace theearlier version of the TCLP promulgatedas part of the land disposal restrictionsprogram.

Today's rule incorporates a schedulefor compliance that classifies theuniverse of potentially affected TCwaste handlers into two groups: (1) Allgenerators of greater than 100 kg/monthand less than 1,000 kg/month ofhazardous waste (small-quantitygenerators) must come into compliance

with the subtitle C requirements formanagement of their TC waste within 1year, and (2) all generators of 1,000 kg/month or more of hazardous waste arerequired to comply with all subtitle Crequirements for TC wastes within 6months. The phased schedule forcompliance is further discussed insection V.

Wastes identified as hazardous underthe Toxicity Characteristic will alsobecome hazardous substances undersection 101(14) of the ComprehensiveEnvironmental Response,Compensation, and Liability Act of 1980(CERCLA), as amended. Today's ruleamends the list of reportable quantities(RQs) in 40 CFR part 302 by addingappropriate values for each of the new25 TC toxicants. All of the newly-



designated TC toxicants are alreadylisted as CERCLA hazardoussubstances. The RQs being promulgatedare the same as those that already applyto all materials containing thesehazardous substances.

Today's rule defers applicability ofthe TC to one type of waste andexempts another. First, the Agency isdeferring the applicability of the TC topetroleum-contaminated media anddebris at sites subject to the RCRAUnderground Storage Tank (UST)cleanup regulations under part 280. (Seesection 111.1.6.) Second, EPA has decidedto exempt from today's rule certainpolychlorinated biphenyl (PCB) wastesthat are fully regulated under the ToxicSubstances and Control Act (TSCA) andwould be identified as hazardousbecause of today's rule (See sectionIII.J.7.).

In portions of the existing codifiedwaste regulation of title 40, chapter I,parts 261 through 265, the EPTC isnamed. Today's action of promulgatingthe TC necessitates amendment of thesereferences to the EPTC. This amendmentwhich replaces references to the EPTCwith the words "ToxicityCharacteristic" applies to the followingsections of 40 CFR: 261.4(b)(6)(i) not(A)(B)(C); 261.4(b)(9),-264.301(e)(1),265.221(d)(1) and 265.273(a).

In §§ 264.301(e)(1) and 265.221(d)(1), inaddition to amending reference to theEPTC, the universe of constituentsremains the same as the EPTC. Toaccomplish this, the constituents D004-D017, the EPTC constituents, arespecifically named as those constituentswhich would not render the wastehazardous by the TC.

As discussed below, the Agency willcontinue to refine the TC in order toprovide greater accuracy andcomprehensiveness in identifyinghazardous waste based on the waste'stoxic constituents. However, the Agencybelieves that today's rule fulfills thestatutory mandates under sections3001(g) and 3001(h).

II. Response to Major Comments andAnalysis of Issues

The Agency received many commentson the June 13, 1986 proposed rule and inresponse to subsequent notices. TheAgency has carefully considered allcomments in the preparation of this finalrule. To facilitate the evaluation andresponse to comments, the Agencygrouped the comments into tencategories. The categories are asfollows:A. General ApproachB. Constituents of ConcernC. Chronic Toxicity Reference LevelsD. Use of Generic DAFs

E. Application of a Subsurface Fate andTransport Model

F. The TCLPG. Testing and Recordkeeping

RequirementsH. Applicability to Wastes Managed in

Surface ImpoundmentsI. Relationship to Other RCRA

RegulationsJ. Relationship to Other Regulatory

AuthoritiesIn this preamble, the Agency provides

summaries of and responses to majorcomments. Readers are invited to referto background documents (Refs. 1, 2, 3,and 4) for complete summaries andresponses to all comments.

A. General Approach

1. Expanded Use of Hazardous WasteCharacteristics.

The TC revisions specified in today'srule refine and expand the EPTC. Mostcommenters stated that increasedreliance on hazardous wastecharacteristics is a reasonable approachto defining hazardous waste. Somecommenters stated a preference for thehazardous waste characteristicmechanism over the alternative listingmechanism for identifying hazardouswastes. They noted that thecharacteristics are designed to measuredirectly the risks that subtitle Cregulations are meant to control.Another advantage mentioned bycommenters is that hazardous wastecharacteristics apply uniformly to allwastes, regardless of source.

A few commenters, however, objectedto the expanded use of hazardous wastecharacteristics. Some of thesecommenters questioned the Agency'sauthority to develop the TC. Onecommenter asserted that RCRA section3001(h) does not authorize EPA to takethe action of adding the proposedorganic constituents to the list of TCconstituents. Another argued that thelegislative history of HSWA indicatesthat changes in the leaching procedureshould address the leaching of toxicmetals only. This commenter claimedthat the Agency had exceeded itsstatutory mandate by modifying the TCto include organics.

EPA strongly disagrees with thosecommenters who argued that theAgency lacks authority to expand theTC. The Agency's approach toidentifying hazardous wastes through aself-implementing characteristicsprocedure was well established in 1984,when Congress passed HSWA. HISWAnot only confirmed the validity of EPA'sapproach to identifying hazardouswastes by characteristics, but alsodirected the Agency to expand the scope

of the TC. RCRA section 3001(h) states".* * the Administrator shall

promulgate regulations under thissection identifying additionalcharacteristics of hazardous waste,including measures or indicators oftoxicity." Thus, the plain language of thestatute authorizes EPA to broaden theTC.

Other commenters acknowledgedEPA's authority to expand the TC, butoffered policy arguments against the useof this mechanism for identifyinghazardous wastes. Most commenterswho argued against expanded use ofcharacteristics favored use of the listingmechanism instead of an expanded TC.Some of these commenters noted thatlistings do not present the sametechnical problems of precision andaccuracy as the characteristics. Othersstated that listings are more easilyenforced since they are not dependentupon use of a leaching procedure.Finally, some commenters claimed thatby expanding the toxicity characteristicinstead of listing additional wastes, EPAis unfairly shifting the burden foridentifying hazardous wastes onto theshoulders of the regulated community.

The Agency maintains that theexpanded use of characteristics, inaddition to being consistent with thestatutory mandate, offers advantagesover listing for identifying broadcategories of clearly hazardous waste.Establishing a characteristic allows theAgency to identify through one rulethose wastes which are reasonablycertain to pose a threat to human healthand the environment by virtue of aninherent characteristic withoutexpending vast Federal resources tostudy, characterize, and list numerousindividual wastestreams. Since theAgency sets regulatory levels highenough to assure that wastes exhibitingthe characteristic are hazardous, thecharacteristic approach does not bringwastes into the subtitle C system whichdo not present a substantial present orpotential hazard to human health andthe environment. By contrast, a listing,since it applies to all wastes that meet alisting description, may capture someindividual wastestreams that do notactually pose a threat to human healthand the environment. Generators maypetition for delisting if this occurs;however, the delisting process can beburdensome to the petitioner and toEPA.

The Agency believes that thecharacteristic approach has thefollowing advantages. First, it is lessburdensome for the regulatedcommunity because the characteristicapproach limits over-inclusiveness,



Second, reducing the potential ofincluding wastes that do not, in fact,present-a threat conserves hazardouswaste management capacity andAgency administrative and enforcementresources for waste managementactivities that warrant priority attention.Finally, if necessary, a characteristiccan be adapted quickly to possiblefuture changes in science or technology,such as lower quantitation limits.

EPA acknowledges that there are alsosome advantages in using the listingmechanism for identifying hazardouswastes, particularly with respect to easeof implementation; the Agency thus willretain the listing approach as analternative mechanism for identifyinghazardous wastes. The Agencycontinues to believe that both thecharacteristic and listing approaches arevalid and useful tools in identifyinghazardous wastes that are subject tosubtitle C regulation.

Finally, the Agency disagrees withcommenters who contend thatcharacteristics impose an unfair burdenon the regulated community. Since theestablishment of the hazardous wasteidentification framework in 1980, EPAhas recognized that the primaryresponsibility for determining whetherwastes exhibit hazardous wastecharacteristics rests with generators. Inaccordance with this, one of two criteriafor establishing new characteristics isthat they must be measurable bystandardized and available testingprotocols or reasonably detected bygenerators through their knowledge ofthe waste (see 40 CFR 261.10). Further,the regulations do not require testing; agenerator may apply knowledge of thewaste to determine if it is hazardous (40CFR 262.11).

2. Mismanagement Scenario

Hazardous waste characteristics aredesigned to identify solid wastes thatpose a threat to human health and theenvironment when improperly managed(RCRA section 1004(5)). Therefore, indeveloping the TC, EPA's first task wasto determine how wastes mightplausibly be mismanaged. Themismanagement scenario that both wasreasonably realistic and presented thegreatest environmental risks could thenbe chosen as the reasonable worst-casescenario and used as the basis for therevised characteristic. Specifically, thecharacteristic would be designed toidentify any wastes from which toxicconstituents would be likelyto pose athreat to human health and theenvironment when managed inaccordance with the selected scenario.In this way, EPA ensured that wasteswould be adequately controlled,

regardless of the manner in which theyare actually managed.

In the June 13, 1986 proposal, EPAconsidered several alternativemismanagement scenarios for use in thedevelopment of the TC rule, includingsegregated management, co-disposalwith municipal solid waste (themismanagement scenario evaluated inthe existing Toxicity Characteristic), co-disposal with industrial waste in alandfill subject to subtitle Drequirements, and co-disposal withindustrial waste in a landfill subject tosubtitle C requirements that sufferssome form of containment-systemfailure. The Agency rejected the subtitleC scenario as unrealistic because it isunlikely that waste generators woulddispose of their wastes in the moreexpensive subtitle C landfills unlessrequired to do so. Thus, it would not bea realistic scenario.

EPA determined that each of theremaining options was a plausiblemismanagement scenario since mostwastes are or may be managed in thesetypes of land disposal facilities. TheAgency rejected the segregatedmanagement or "monofill" scenario onthe grounds that it did not represent arealistic worst-case practice. Facilitiesdedicated to the management of onlyone waste or the wastes of only onegenerator (i.e., a "monofill") are likely topose less of a hazard than generalmunicipal or industrial landfills becausethe design and operation problems for amonofill are simpler and the operatorsgenerally have considerably moreinformation on the properties of thewastes that are managed. Also,industrial monofills generally do notgenerate organic acids that result in anaggressive leaching medium, as is thecase for municipal landfills. Thus,industrial monofills pose less of apotential hazard than municipal solidwaste (MSW) landfills. EPA alsorejected the general (as opposed to"monofill") industrial landfill scenarioon similar grounds (i.e., the generatedleaching medium may not, in somecases, be as aggressive as in a municipallandfill). The Agency therefore retainedthe municipal landfill scenario as thereasonable worst-case mismanagementscenario for the revised TC.

a. Extent to Which Scenario isReasonable. Several commenterschallenged the municipal landfillscenario, claiming that it is based on anunreasonable assumption about the wayin which industrial solid wastes aremanaged. These commenters claimedthat industrial wastes are rarelydisposed in MSW landfills. If landfilledat all, these wastes are more likely to be

disposed in industrial landfills. Inaddition, industrial wastes arefrequently managed in ways other thanlandfill disposal (e.g., incineration,recycling, treatment on the land, ortreatment in surface impoundments).Thus, commenters argued, it isinappropriate to base the TC on themunicipal landfill scenario.

EPA fully recognizes that not allindustrial wastes are managed in MSWlandfills. Nevertheless, the Agencycontinues to believe that the MSWlandfill scenario is reasonable becausesuch landfills have traditionallyaccepted unregulated industrial wastes.It is for this reason that the MSWlandfill scenario was originallyestablished as the basis for the EPTC(see 45 FR 33112, May 19, 1980).Although fewer types of industrialwastes are being disposed in municipallandfills now as compared to a fewyears ago, EPA's information confirmsthe continued appropriateness of thisscenario. The "State Subtitle DRegulations on Solid Waste Landfills"(Ref. 5), and the "National Survey ofSolid Waste (Municipal) LandfillFacilities" (Ref. 6) indicate that moststates impose few restrictions, if any, onthe types of nonhazardous wastesaccepted at these facilities; moreover, asubstantial quantity of the wastesreceived (typically five to eight percent)are industrial wastes. Thus, EPAcontinues to believe that the municipalsolid waste landfill scenario representsthe most appropriate reasonable worst-case mismanagement scenario.

Many commenters suggested that EPAgrant exceptions or variances for wastesthat are not co-disposed with MSW. Inthis way, the TC would apply only tothose wastes that are actually managedin accordance with the underlyingmismanagement scenario. Thecommenters noted that EPA couldseparately develop alternativecharacteristics for wastes managed inother ways to ensure adequateprotection of human health and theenvironment.

After careful consideration, EPA hasdecided not to adopt this suggestion forvarious reasons. Applying the TC onlyto wastes actually managed assuggested in the mismanagementscenario would involve the creation of amanagement-based approach toidentifying hazardous wastes. EPA'scurrent approach to establishingcharacteristics which identify certainwastes as hazardous is not contingentupon the way individual wastes areactually managed. Rather, consistentwith the RCRA Section 1004(5)definition of hazardous waste, EPA is


Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990 /Rules and Regulations

identifying waste " * * that mayposea substantial present or potential hazardto human health and the environmentwhen improperly * * managed"(emphasis added].

EPA has considered the possibility ofdeveloping management-basedcharacteristics, i.e., differentcharacteristics for categories of wastedepending on how they are typicallymanaged. However, the Agency believesthat such an approach would present anumber of difficulties. For instance, amanagement-based approach tohazardous waste identification couldsubstantially complicate effectiveimplementation of the RCRAregulations. In particular, it is notalways possible to determine-at thepoint of generation, during transport, oreven as a waste enters a treatment,storage, or disposal facility-how asolid waste will ultimately be managed.EPA believes that the most effective andappropriate approach is to identifyhazardous waste characteristics, notaccording to the ways in whichindividual wastes are managed, but byidentifying properties of wastes thatwould pose a threat to human healthand the environment if improperlymanaged. The Agency maintains thatco-disposal with MSW is a 'mismanagement scenario that isreasonably realistic for most industrialsolid wastes.

Another group of commenterssuggested that EPA exempt broadclasses of wastes that, because of theirvolume or physical properties, cannotreasonably be placed in a municipallandfill. Commenters specificallymentioned wastewaters, mining wastes,and municipal waste combustion ash.They noted that separate characteristicscould be developed for each class ofwastes that is excluded from the TC,based on the most appropriatemismanagement scenario for eachindividual category of waste.

After careful consideration of thesecomments, the Agency agreed that onecategory of wastes, wastewaters, mightwarrant special consideration based onthe fact that the mismanagementscenario may not be reasonablyapplicable. Thus, EPA published aSupplemental Notice of ProposedRulemaking on May 18, 1987 (52 FR18583), which asked for comment on thedevelopment of separate regulatory-levels for wastewaters. EPA receivedconsiderable information in response tothis notice, and reviewed additionalinformation on management ofwastewaters in surface impoundments.After analysis of the waste managementtechniques, attenuative mechanisms,

and hydrogeologic processes that governconstituent transport from surfaceimpoundments, the Agency concludedthat the DAFs for nondegradingconstituents managed in surfaceimpoundments were similar to those forthe same constituents managed inlandfills. Thus, for today's rule, theAgency determined that there is notechnical basis for setting separateregulatory levels for wastewaters. Thisissue is discussed in more detail insubsection C, and further in sectionsII.E (Application of a Subsurface Fateand Transport Model] and III.H(Applicability to Wastes Managed inSurface Impoundments).

The Agency also does not agree thatthe mismanagement scenario isunreasonable for either non-exemptmineral processing wastes or municipal-combustion ash. Although large volumewastes from the extraction,beneficiation and processing of ores andminerals are currently exempt fromsubtitle C regulation and will not beaffected by the TC rule, small volumemineral processing wastes which maybe subject to subtitle C regulation (see54 FR 36592) can plausibly be disposedin municipal landfills. Municipal wastecombustion ash can also be disposed inmunicipal landfills; in fact, the Agencyestimates that only about 30 percent ofmunicipal waste combustion facilitiesutilize ash monofills, and rely.principally on municipal landfills for ashdisposal. Issues related to the regulationof municipal waste combustion ash arediscussed further in section 111.1.5.

b. Worst-Case Scenario Selection. Afew commenters agreed with EPA thatthe municipal landfill scenario isreasonable, but, they claimed that thescenario does not represent areasonable worst case. Most of thesecommenters asserted that co-disposal ina subtitle D industrial landfill posesmore of a threat to human health andthe environment than disposal in anMSW landfill. They pointed out, forexample, that the regulatory standardsfor subtitle D industrial waste landfillsare generally no more stringent thanthose for municipal landfills. Thecommenters further claimed that theleaching media in industrial landfills arefrequently more aggressive than those inmunicipal landfills, especially whenacids, bases, and solvents are present.Finally, the commenters noted thatwastes placed in industrial landfills arenot diluted with domestic wastes, asthey are in a municipal landfill. Thecommenters concluded that because theTC proposal was based on a scenariothat was less than worst-case, it would

not adequately protect human healthand the environment.

The Agency believes that the leachingmedia in a subtitle-D municipal landfillis typically more aggressive thanleaching media generated in industriallandfills due to the formation of acidsduring decomposition of putresciblewastes. "State Subtitle D Regulations onSolid Waste Landfills" (Ref. 5) showsthat putrescible wastes are accepted atmost subtitle D municipal landfills,while "Summary of Data on IndustrialNon-Hazardous Waste DisposalPractices" (Ref. 7) shows solvents, acids,and bases (which can also increase theaggressiveness of leachate) aregenerally not disposed of in subtitle Dindustrial landfills. The potential for theformation of 'cids from decompositionof putrescibles in a subtitle D municipallandfill is greater than the potential ofacids, bases, or solvents being presentin a subtitle D industrial landfill,therefore supporting the municipallandfill scenario as a reasonable worst-case.

EPA acknowledges that, in certaincircumstances, industrial wastes maypose more of a threat when placed in asubtitle D industrial landfill than whenplaced in a subtitle D municipal landfill.However, EPA believes that thissituation will only occur in certaincircumstances and thus represents aworst case rather than a reasonableworst case. Should the occurrence ofthis situation increase in frequency, theAgency will reconsider its approach forregulating these wastes in the future.

c. Extent to Which theMismanagement Scenario for WastesManaged in Surface Impoundments isAppropriate. In the May 18, 1987 notice,the Agency stated that it is consideringdeveloping a separate mismanagementscenario applicable to wastes that aremanaged in unlined surfaceimpoundments. Developing a surfaceimpoundment scenario, in addition tothe landfill scenario, would mean thatthe TC would have two different sets ofregulatory levels. Waste generatorswould first have to determine whichscenario is appropriate and then wouldbe responsible for evaluating whethertheir waste exceeded the applicableregulatory levels.

In the notice, the Agency requestedcomments on the appropriate criteria tobe used in determining whether thecharacteristic should apply to aparticular waste. The Notice suggestedthree possible approaches:

1. The ':management-based" approach.which would apply only to those wastesactually managed in impoundments

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2. The "physical property-based" approach,which would apply to those wastes having acertain physical property indicating that theyare likely to be managed in surfaceimpoundments (e.g., percent solids less than 5percent); and

3. The "definition-based" approach, whichwould apply to those discharged wastewatersthat are subject to regulation under eithersection 402 or section 307(b) of the CleanWater Act.

Commenters from various industriesgenerally supported a separatemismanagement scenario because theydo not believe that the landfillmismanagement scenario is appropriatefor aqueous wastes managed in surfaceimpoundments. Most of thesecommenters requested that EPA adopteither the management-based approachor the definition-based appioach.

Other commenters, however, opposeda separate mismanagement scenario forwastes managed in surfaceimpoundments. These commenterscontended that the surfaceimpoundment mismanagement scenariowould not be a reasonable worst-casescenario, particularly if the scenariomodeled biodegradation, becausesignificant biodegradation does not-occur in all impoundments. In addition,the commenters stated that if thedevelopment of a surface impoundmentmismanagement scenario results in twosets of regulatory levels, requirementsfor storage, handling, and transportationof a waste would be based on themanagement practice that the generatorassumes or expects will actually occur.These commenters were opposed to thisresult and noted that wastes may notalways be ultimately disposed in themanner originally intended by thegenerator.

After receiving these comments, theAgency decided to revisit the issue ofwhether or not a separatemismanagement scenario is necessaryfor surface impoundments due toinappropriately low regulatory levels.As described in section III.E.2, theAgency believes that evaluation of thephysical phenomena that affect dilution/attenuation factors (DAFs) indicatesthat the DAFs generated for landfills aresimilar, if not greater than, DAFs forsurface impoundments (i.e., theregulatory levels for surfaceimpoundments would be equal to ormore stringent than those for landfills).To confirm this conclusion, EPA theninvestigated whether results frommodeling a surface impoundmentscenario would in fact be significantlydifferent from modeling a landfillscenario. As described later in thispreamble, for nondegradingconstituents, EPA calculated the 85th

and 90th percentile DAFs for landfills(which ranged from 134 to 47) and the85th and 90th percentile DAFs forsurface impoundments (which rangedfrom 111 to 51). The surfaceimpoundment results were obtained byusing the updated model (EPACML) forthe landfill scenario with leachategeneration and environmentalparameters (e.g., well distances, facilityareas) derived from surfaceimpoundment data.

As a result of this analysis, EPA isconfident that the results from modelingof the landfill mismanagement scenarioare also appropriate for wastesmanaged in surface impoundments (i.e.,the DAFs are of the same order ofmagnitude). The Agency therefore doesnot plan to develop a separate surfaceimpoundment mismanagement scenarioat this time. Since the modeling resultsindicate that the dilution/attenuationfactors for non- and minimallydegrading constituents are all on theorder of 100, the Agency has concludedthat a single value of 100 is anappropriate choice for use inestablishing the regulatory levels for allof the constituents addressed in today'srule. (See section III.E. of this preamblefor an additional explanation of EPA'smodeling efforts and choice of DAFs.)3. Targeted Risks

Several commenters argued that, evenif the co-disposal mismanagementscenario was appropriate, EPAimproperly focused on a few selected'risks from this scenario. Specifically,they claimed that the Agency restrictedits consideration to human health risksresulting from ground watercontamination. A number ofcommenters stated that the Agencyshould consider additional routes ofhuman exposure, such as airvolatilization, surface runoff, and directcontact. One commenter questionedwhy EPA was not employing the samemultimedia risk and exposure modelsthat were originally proposed for use inthe land disposal restrictions program(see 51 FR 1602, January 14, 1986).

A few commenters further suggestedthat EPA take environmental risks (e.g.,aquatic toxicity) into account, ratherthan concentrating exclusively onhuman health risks. They noted thatRCRA section 3001(g), on which the TCrule is based, directs EPA to makechanges in the EPTC so that it"accurately predicts the leachingpotential of wastes which pose a threatto human health and the environmentwhen mismanaged" (emphasis added).

EPA acknowledges that thecharacteristic being promulgated todayfocuses on human health risks from

ground water contamination. However,the Agency does not believe that asingle characteristic is capable ofidentifying all wastes that present athreat to human health and theenvironment. The present TC revisionsare only the first step in a long-termstrategy to refine and expand thehazardous waste identification program.Future characteristics may addresshazards other than human health risksresulting from ground watercontamination. EPA continues tobelieve, however, that ground watercontamination, as a route of humanexposure, is a priority concern.

4. Accuracy

Several commenters asserted that theproposed TC revisions failed to fulfillthe statutory mandate to improve the*'accuracy" of the characteristic as apredictor of the leaching potential ofsolid wastes. Specifically, thesecommenters argued that, even if EPAselected the proper mismanagementscenario, the Agency failed to model thetargeted risks in a reasonable orappropriate manner. (Many of thecommenters addressing this issue alsofocused on the accuracy of individualelements of the characteristic, such asthe TCLP, the subsurface fate andtransport model, or the chronic toxicityreference levels. These specific concernsare considered in sections III.B throughIII.F of today's preamble.)

A number of the commenters on theissue of accuracy concentrated on theinterrelationship between the variouselements of the TC. These commenterspointed out that EPA had employedconservative assumptions at each stepin the development of the revisedcharacteristic. They argued that even ifthese assumptions were reasonable inisolation, they would not be reasonablein combination. According to thesecommenters, the effect of compoundingmultiple conservative assumptionswould be a characteristic that is.unreasonably conservative, therebyresulting in costly overregulation.

Other commenters maintained theopposite position and stated that EPAhad employed non-conservativeassumptions for many elements of thecharacteristic. These commentersbelieve that these assumptions result ina characteristic that is not conservativeenough and, thus, not sufficientlyprotective of human health and theenvironment.

The Agency disagrees withcommenters' assertions that theelements of the TC are either tooconservative or not conservativeenough. The TC, in particular the fate,



and transport model used to establishthe dilution/attenuation factors (DAFs),requires the selection of numericalvalues for many parameters. Ratherthan selecting values for each parameterbased upon isolated judgments as towhat constitutes a "reasonable worstcase" value, the Agency used the fullrange and distribution of values for' allparameters for which such data wasavailable. By implementing these datasets through a monte carlo simulation,the model output (i.e., the frequencydistribution of DAFs) is as realistic aspossible and spans the range of allpossible outcomes rather thanrepresenting only the "best case,""reasonable worst-case," etc. That is,the model output represents all cases,arrayed according to their frequency ofoccurrence, and does not reflect anyqualitative judgement as to whatconstitutes a "reasonable worst case" orany other "case." Accordingly, thedetermination as to which DAF valuerepresents any particular "case" issolely dependent upon the selection ofthe cumulative frequency level. TheAgency's selection of the cumulativefrequency level is discussed in sectionlII.E.4.d.

EPA does agree with commenters whorecommended that the originallyproposed subsurface fate and transportmodel could be revised to morerealistically represent land disposalsettings. Accordingly, EPA has modifiedthe original model (EPASMOD) and hascollected and incorporated new datainto the model. These modifications anddata are described in greater detailbelow (section lIl.E). The reader isreferred to the Response-to-CommentsBackground Document for theSubsurface Fate and Transport Module(Ref. 1), which presents in detail each ofthe technical issues raised by publiccomments on the model and theAgency's responses to these issues. EPAbelieves that with these changes, thefinal TC rule represents a reasonableapproach to the identification ofhazardous wastes.

5. Solvent OverrideIn the June 13, 1986 TC proposal, the

Agency discussed the possibility ofincorporating a solvent "override"criterion into the TC because thepresence of large amounts of solvents ina waste may result in leachate from thewaste mobilizing hazardous constituentsfrom co-disposed nonhazardous waste.The Agency considered settingregulatory levels for solvents based onthe total concentration of solvent foundin the TCLP extract.

Many commenters claimed thatmobilization of toxicants in municipal

landfills by industrial solvents isimprobable. Commenters argued thatthere are no data to support thehypothesis that industrial solventswould alter the solubility of hazardousconstituents in municipal waste. Thesecommenters asserted that, at levelsbelow their solubility in water, organicsolvents exert very little influence onthe solubility of other organics. Giventhe low concentrations of solventwastes permitted for land disposal, thecommenters contended that there islittle probability that mobilization willoccur. Commenters emphasized that, ingeneral, subtitle D landfills do notaccept organic solvents or liquids. Mostindustrial solvents already are listedhazardous wastes under 40 CFR 261.32and 261.33 and will be managed insubtitle C hazardous waste facilities.Also, commenters contended that thecontribution that industrial solvents willhave on the solvent power of a solid-waste-landfill leachate is smallcompared to the contribution fromsolvents in household and smallquantity generator waste.

Other commenters, however,expressed their support for EPA'sproposal to characterize a waste by itsability to leach hazardous constituentsfrom co-disposed wastes. They urgedthat a method be devised to monitor theinfluence that solvents have on thesolubility of other waste constituents.One commenter suggested that the TCLPleachate could be tested for its ability todissolve hazardous waste.

After careful consideration of thecomments on this Issue, EPA hasdecided not to include a solventoverride in today's revision of the TC.EPA is not convinced by commenterswho stated conclusively thatmobilization of toxicants In municipallandfills by industrial solvents isimprobable. EPA also is not convincedthat the solvent contribution ofindustrial wastes at municipal landfillsis small compared to that of houselholdwaste and small quantity generatorwaste. Moreover, the comparison tohousehold waste and small quantitygenerator waste is not relevant to theissue of whether industrial wastesshould be regulated based on solventproperties. However, the Agency doesagree that there is insufficient dataconcerning the degree to whichindustrial solvents would mobilize otherhazardous constituents and the amountof solvent wastes that are actually landdisposed. Given this lack of data, asolvent override has not been includedin today's rule. However, an overridemay be considered in future rulemakingsif information becomes available that

indicates a characteristic based onsolvent properties is warranted.

One commenter claimed that RCRAdoes not authorize the imposition ofrestrictions based on toxicity simplybecause a substance can mobilize otherconstituents. The commenter assertedthat the authority may reside elsewherein RCRA, but in that case, a separaterulemaking, not involving the TC, shouldtake place.

EPA does not agree; RCRA clearlyauthorizes EPA to regulate a waste ashazardous on the basis of its ability tomobilize other constituents. Further,regulating a waste as hazardous basedon its ability to mobilize otherconstituents could be appropriatelyachieved through the characteristicmechanism. A solid waste is defined ashazardous if its "physical" or"chemical" characteristics "may pose asubstantial present or potential hazardto human health or the environmentwhen improperly treated, stored,transported, disposed of, or otherwisemanaged" (RCRA section 1004(5)). Thecapacity to mobilize toxic constituentsfalls within the definition of a physicalor chemical characteristic of a wastewhich may pose a substantialenvironmental or health hazard. Thus,EPA may incorporate this approach intoits characteristic waste identificationscheme in the future.

Related to the Issue of solubilization,another commenter asserted that if achemical's capacity for mobilization isconsidered, treatment implemented toprevent mobilization (e.g., stabilization,containment, and chemical conversion)should be given equalconsideration.

The TCLP does considerimmobilization in the context of the co-disposal mismanagement scenario. TheTCLP was developed to simulateleaching in a municipal landfill,addressing the degree of mobility (or,conversely, immobility) of both organicand inorganic compounds. Wastes thathave been treated to preventmobilization are less likely to leachtoxic constituents. Such wastes maycease to exhibit the TC and wouldtherefore no longer be consideredhazardous wastes. Thus, the TCLPalready accounts for immobilization oftoxic constituents in a waste. However,if wastes that have been treated toprevent mobilization fail the TC, EPAbelieves that the wastes in questionshould be managed as hazardouswastes.

B. Constituents of Conce."n

As noted above, the proposed TC ruleidentified 52 constituents that, if presentat specified levels in a waste extract,

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would render the waste "hazardous"under RCRA subtitle C. Fourteen of theconstituents were already encompassedby the existing EPTC. The selection ofthe remaining 38 constituents was basedon the availability of adequate andverified data necessary for establishing(1) a chronic toxicity reference level and(2) a constituent-specific DAF. Thus, theAgency focused on those constituentsfor which there existed a promulgated orproposed Maximum Contaminant Level(MCL), a Reference Dose (RfD), or aRisk-Specific Dose (RSD), and for whichthere were sufficient data onenvironmental fate and transportprocesses to support modeling of aconstituent-specific DAF. The June 13,1986 proposal also announced EPA'sintention to expand the list of TCconstituents as additional data becameavailable.

1. Final List of ConstituentsThe Agency is finalizing the

regulatory levels for 25 of the proposedorganic constituents (see Table B-1) thatdo not readily hydrolyze and for which asteady-state subsurface fate andtransport model is appropriate. EPAmay promulgate or repropose (aswarranted) regulatory levels for theother organic constituents at a futuredate.

TABLE B-1 .- LIST OF ORGANIC CONSTITU-ENTS INCLUDED IN THE EXPANDED TCRULE

Benzene ............ Hexachloro-1,3-butadiene

Carbon tetrachloride . HexachlorobenzeneChlordane ............................ HexachloroethaneChlorobenzene .................... Methyl ethyl ketoneChloroform ........................... Nitrobenzenem-Cresol .............................. Pentachlorophenolo-Cresol ............................... Pyridinep-Cresol .............................. Tetrachloroethytene1,4-Dichlorobenzene .......... Trichloroethylene1,2-Dichloroethane ............. 2,4,5-Trichlorophenol1,1-Dichloroethylene .......... 2,4,6-Trichlorophenol2,4-Dinitrotoluene ............... Vinyl chlorideHeptachlor (and its

hydroxide).

Constituents with regulatory levelsestablished under the EPTC willcontinue to be regulated at previouslyestablished levels, but will requireapplication of the new TCLP instead ofthe EP.

2. Toxicants Versus IndicatorParameters

A few commenters recommended thatEPA abandon its current focus onindividual toxicants and rely instead onsuch indicator parameters as totalorganic carbon or total organichalogens. The commenters argued thatsuch an approach would broaden the

effective scope of the rule and reducethe burdens associated with makinghazardous waste determinations.

The Agency does not believe it wouldbe appropriate to use indicators as partof the TC. Indicators generally are usedas screening levels or to set priorities forfurther investigations. They do notachieve sufficient specificity for theregulatory purposes of the TC. Forinstance, the two indicators suggestedby the commenters do not in any wayreflect differences in toxicities amongorganic constituents. Consequently, useof these indicators could lead to bothnonhazardous wastes registering ashazardous and wastes that are clearlyhazardous registering as nonhazardous.

3. Method for Selecting ConstituentsSeveral commenters questioned the

manner in which EPA selected toxicantsfor inclusion in the TC proposal. Someof these commenters charged that theAgency's choice of toxicants wasentirely arbitrary. Others claimed thatEPA had based its selections solely onthe availability of toxicologic andhydrogeologic data, without consideringthe magnitude of the hazards presentedby the constituents.

The commenters, in general,encouraged EPA to develop specificprocedures and criteria for decidingwhich constituents should be includedin the TC. A few commenters offeredparticular suggestions for the types offactors that might be considered inevaluating toxicants. The recommendedfactors included (1) the mobility andpersistence of the constituents, (2) thefrequency with which particularconstituents have been found inindustrial wastes or leachates from suchwastes, and (3) the extent to whichvarious constituents have been detectedin ground water supplies inconcentrations capable of posing athreat to human health and theenvironment.

EPA believes that its method forselecting TC constituents is bothrational and consistent with thestatutory mandate. While selection ofconstituents in today's rule is in partbased on available toxicological data, itshould be noted that both the fate andtransport of constituents and themagnitude of hazards posed were alsogiven consideration. The toxicants forwhich regulatory levels are beingpromulgated today are persistent andcan represent a substantial threat tohuman health and the environment.Because of the lack of reliable data onthe frequency with which certain toxicpollutants are found in leachates orground water, an approach relying onsuch information would not provide an

accurate and valid basis for selectingconstituents. Further, where data doexist concerning the frequency at whichcertain constituents are found in theenvironment, accompanying informationabout risk posed in the environment isoften absent.

Although the Agency proposed levelsonly for toxicants for which it hasadequate and verified data, generallythese data are available because thesetoxicants do represent a substantialthreat to human health and theenvironment. The Agency will consideradding constituents as additionaltoxicological data and other supportingdata become available; in making suchdecisions, the Agency will consider thefactors identified by the commenters.Until such data are available, there is notechnical basis to determine at whatlevel a waste is hazardous under the TC.

A number of commenters argued thatEPA was needlessly "cluttering" thecharacteristic with low-priorityconstituents that are either not beingproduced in the United States or areprimarily found in wastes that arealready subject to regulation.

The Agency does not agree that asubstance no longer manufactured in theU.S. will not pose a threat from wastedisposal. Some such substances may becontained in products imported into theU.S. Also, wastes generated duringcleanup at Superfund sites or RCRAcorrective action sites may exhibit theTC due to the presence of theseconstituents in wastes disposed at sometime in the past. Further, theconstituents could be manufacturedagain in the future.

Several of the toxicants listed intoday's rule also appear among the listof discarded commercial chemicalproducts, off-specification products, andcontainer and spill residues, as listed in40 CFR 261.33. A group of commentersargued that it would be redundant toestablish regulatory levels for thesetoxicants because they are alreadyregulated as listed hazardous wastes.Similarly, several commenters arguedthat some other listed wastes areregulated as hazardous wastes primarilybecause they contain constituents thatwill be regulated under the new TC.

EPA does not agree that setting levelsfor the selected toxicants would beredundant. While it is true that many ofthe newly designated TC constituentsare constituents in wastes that arespecifically listed as RCRA hazardouswastes, the current listings do not coverall of the wastestreams that may containthe TC constituents. For example, thecommercial chemical product listings in40 CFR 261.33 primarily encompass



unused products and off-specificationvariants of products that are genericallyidentified using the name of a singletoxic constituent; however, the listingswould not cover other wastestreamscontaining the same constituent. Thelistings in 40 CFR 261.32 specify only alimited number of wastestreams thatcontain TC constituents. As anotherexample, the spent solvent listings in 40CFR 261.31 cover only those solventsthat are used for their "solvent"properties (i.e., to solubilize or mobilizeother constituents). The current listingsdo not encompass process wastes wheresolvent constituents are used asreactants or ingredients in theformulation of commercial chemicalproducts. The Agency has previouslystated that it is expanding the TC tobring these wastestreams into thehazardous waste management system(see 50 FR 53317, December 31, 1985).Thus, the Agency is appropriatelypromulgating TC regulatory levels forsome constituents that have been usedas the basis for listings.

One commenter argued that EPA'sapproach in selecting TC constituentswas too restrictive, ensuring that manytoxic constituents may never beregulated. The commenter emphasizedthat reliance on MCLs, RfDs, and RSDsdoes not provide a comprehensive list ofconstituents for which reliabletoxicological data exist. In addition, thecommenter noted that reliance onhuman health data does not necessarilyaddress hazards to the environment.

EPA disagrees with the commenter'sfirst point. Reliance on MCLs, RfDs, andRSDs uses the most sound toxicologicdata base available to the Agency. Atpresent, there are more than 365constituents with verified toxicity levelsavailable for EPA use. In regard to the'second point, the Agency recognizesthat factors other than human healtheffects are also important to the overallpiotection of the environment, butpoints out that the purpose of thischaracteristic is to identify wastes thatpose hazards to human health via aground water contamination route. Inregard to the other factors, the Agency issupporting a research effort focusing onthe determination of action levels forecological effects and evaluatingappropriate exposure assessment tools.When sufficient information concerningthese ecological risks is available, theAgency will compare the ecological-risk-based levels to the TC regulatory levelsto determine whether further revisionsto these levels, based on ecological risk,are necessary.

4. Specific Organic Constituents

Many commenters expressed concernover several of the specific organicconstituents that EPA proposed toinclude in the TC. The commentsfocusing on specific toxicants arediscussed below.

a. Vinyl Chloride. A few commentersobjected to the inclusion of vinylchloride in the TC. They suggested thatthe constituent is already adequatelyregulated under the Clean Air Act, theSafe Drinking Water Act, the ToxicSubstances Control Act, and the Food,Drug, and Cosmetic Act (for foodcontact applications.

The commenters are correct in statingthat vinyl chloride and polyvinylchloride are already regulated underother environmental health and safetystatutes. However, none of these otherregulatory authorities address thespecific problem of ensuring againstreleases of vinyl chloride caused by theimproper management of solid wastescontaining this constituent. Mostimportantly, none of the authoritiesdirectly protect ground water suppliesfrom vinyl chloride contamination.Because vinyl chloride is known to betoxic to humans and has been detectedin ground water supplies, EPA believesthat regulating the constituent underRCRA will add significantly to theprotection of human health and theenvironment. An analysis completed aspart of the Regulatory Impact Analysis(Ref. 8) of this regulation indicates thatlarge quantities of wastes currently notregulated as hazardous containconcentrations of vinyl chloride abovethe regulatory levels. Therefore, theAgency believes that RCRA regulationunder the TC is an important expansionof the overall regulatory coverage of thisconstituent which poses a threat tohuman health and the environment.

b. Bis(2-chloroethyl) Ether. Onecommenter questioned whetherincorporating bis(2-chloroethyl) etherinto the TC is appropriate, since only anextremely limited quantity of theconstituent could potentially be releasedinto the environment. The commenternoted that the constituent is used almostexclusively as an intermediate in theproduction of ionene polymers.Moreover, it is handled primarily by asingle facility, which either recycles thematerial or destroys it bybiodegradation prior to discharge undera National Pollutant DischargeElimination System (NPDES permit.

The Agency is not promulgatingstandards for bis(2-chloroethyl) ethertoday. As discussed in section III.E.2.a.7,bis(2-chloroethyl ether) is expected tohydrolyze significantly during transport.

EPA does not have sufficient data toaddress the formation and toxicity ofhydrolysis products. Thus, the Agencyexpects to address appropriateregulatory action for this constituent,along with the other hydrolyzingconstituents, in a future Federal Registernotice.

c. Toxaphene. One commenterquestioned the need to includetoxaphene in the list of TC analytes. Thecommenter argued that toxaphene hasnot been produced in the United Statesfor several years and that generatorsshould not be required to test theirwastes for "phantom" constituents thatare unlikely to be present.

EPA recognizes that toxaphene is nolonger produced domestically. However,because previously generated toxaphenewastes are still being managed intreatment, storage, and disposalfacilities there is still a potential threatto human health and the environmentfrom improper management of wastescontaining this constituent. Thus, wastescontaining toxaphene above theregulatory level should be managed ashazardous wastes.

Moreover, toxaphene has beenregulated as an EP constituent since1980 and today's rule retains the existingregulatory level. Thus, today's rule doesnot alter any regulatory requirementswith respect to toxaphene. The Agencydoes not believe that maintainingtoxaphene as a TC constituent isunnecessarily burdensome to theregulated community. The final TC ruledoes not requite solid waste generatorsto test their wastes. Instead, generatorsmay continue to determine whether theirwastes exhibit the hazardous wastecharacteristics by relying on theirknowledge of the materials andprocesses that they employ (see 40 CFR262.11(c)(2)). Accordingly, generatorswho have reason to believe that theirwastes contain no toxaphene are notspecifically required to test for thatconstituent.

d. Phenol. One commenter urged EPAto delete phenol from the list of TCconstituents of concern because phenolbiodegrades under both aerobic andanaerobic conditions.

The Agency is not including phenol intoday's rule because the steady-stateassumption used in the model tocalculate DAFs in this final rule may notbe appropriate for phenol. The Agencywill promulgate a TC regulatory level forphenol at a later date.

The issue of biodegradation isdiscussed in section III.E.2.a.9 as itpertains to phenol and otherconstituents.

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e. Pentachlorophenol. The Agency isconsidering revisions to the regulatorylevel for pentachlorophenol [PCP)because new health data indicate thatPCP is more toxic than originallyassumed. Two studies of differentgrades of PCP material were conductedby the National Toxicology Program,and the new data indicate that PCP iscarcinogenic in male and female miceunder the conditions of the bioassay..These studies were used to support theproposal to list additional wastes fromthe wood preserving industry (53 FR53282, December 30,1988).

The Agency is today finalizing thehigher regulatory level for PCP althoughthe Agency expects that the regulatorylevel will decrease in the future. EPAhas determined that it is more prudentto effect control at a higher level duringthe period necessary to take commenton the appropriateness of modifying theTC level.

5. Specific Inorganic Constituents

As noted earlier, EPA did not proposeto add any new inorganic TCconstituents in the June 13, 1986proposal. Nevertheless, the Agencyreceived a large number of commentsaddressing the eight metallic speciesthat were already covered by the EPTC.The Agency also received manycomments on the possibility ofproposing TC regulatory levels for nickeland thallium (mentioned in the June 13proposal). The principal comments arediscussed below.

a. Silver. A number of commentersurged EPA to delete silver from the listof TC constituents of concern. Theypointed out that a variety of studieshave demonstrated that the chief effectof silver on humans is argyria, a blue-gray discoloration of the skin andinternal organs. The commenters alsostated that argyria is generallyconsidered a cosmetic effect, rather thana health effect, because it does notimpair the functioning of the body.While the commenters acknowledgedthat free silver ions may be toxic toaquatic life, they claimed that such ionsare rarely discharged into theenvironment. Moreover, they arguedthat even if such ions were discharged,they would quickly be converted intoinsoluble salts, such as chlorides,sulfides, and phosphates. Finally, thecommenters asserted that deleting silverfrom the TC list would be consistentwith current EPA policy. They pointedout that the Agency has not proposed aRecommended Maximum ContaminantLevel (RMCL) for silver in drinkingwater, on the grounds that silver doesnot cause adverse health effects.

EPA acknowledges that an RMCL(now referred to as a MaximumContaminant Level Goal, or MCLG) hasnot been proposed for silver because theonly known adverse effect fromexposure to silver is argyria. However,the Agency has specifically requestedcomments on whether it is appropriateto consider argyria a cosmetic effect asopposed to a health effect (see 50 FR40979, November 13,1985). EPA believesit would be inappropriate to removesilver from the list of TC constituentsuntil this issue is resolved. If EPAdetermines, within the scope of the SafeDrinking Water Act rulemaking, thatsilver does not pose a threat to humanhealth and the environment, the Agencywill consider proposing the deletion ofsilver from the list of TC constituents.

b. Chromium. Several commentersobjected to the inclusion of totalchromium as a TC constituent ofconcern. They argued that onlyhexavalent chromium (Cr(VI)) has beendemonstrated to pose a threat to humanhealth and the environment. Althoughthey acknowledged that triv'alentchromium [Cr[Ill)) can be oxidized tohexavalent chromium under certainconditions, they contend that suchconversion is unlikely to occur in groundwater environments. The commenters,in fact, claimed that iron-bearing soilsare likely to effect the oppositetransformation, from Cr(VI) to Cr(lII).Finally, they stated that even if theoxidation reaction did occur, theresulting Cr(VI) concentrations wouldbe so low as not to present a significantdanger to human health and theenvironment.

EPA continues to believe that totalchromium concentrations should beconsidered in determining whether solidwastes qualify as characteristichazardous wastes. The Agency has longbeen aware of the fact that trivalentchromium is less toxic than hexavalentchromium. Nevertheless, the Agencyalso has been concerned that trivalentchromium could be converted to thehexavalent form under certain plausiblemismanagement conditions. It is for thisreason as well as the fact that theNIPDWS was developed for totalchromium that the regulatory level forchromium in the EPTC was originallyestablished on the basis of totalchromium concentrations (see 45 FR33084, May 19, 1980).

The Agency later proposed to amendthe EPTC so that it would apply tohexavalent chromium rather than totalchromium (45 FR 72029, October 30,1980; see also 48 FR 22170, May 17,1983). This proposal was based on thefact that trivalent chromium has

significantly lower migratory potentialthan hexavalent chromium and is lessmobile if it does migrate from a wastematrix. At that time, the Agency alsobelieved that there was little likelihoodthat Cr(III) could oxidize to Cr[VI) undermost plausible types of improper wastemanagement.

More recent evidence, however,suggests that the conversion fromtrivalent to hexavalent chromium mayoccur in a number of environmentalsituations (see 51 FR 26420, July 23, 1986,fn. 6). For example, Cr{III) has beenfound to oxidize readily to Cr(VI] underconditions found in many field soils.This reaction is catalyzed by manganesedioxide, which is commonly present inboth soils and sediments. Moreover, ithas been shown that water treatmentinvolving chlorination will effectivelytransform Cr(IIl) to Cr(VI). The normalpresence of residual oxidizing capacityin treated water is capable ofmaintaining dissolved chromium in thehigher valence state (50 FR 46966,November 13, 1985). Thus, if trivalentchromium is present in highconcentrations in well water,chlorination can result incorrespondingly high concentrations ofhexavalent chromium at the point ofexposure (i.e., at the tap).

For these reasons, EPA's originalconcerns regarding the potential fortrivalent chromium to be converted tohexavalent chromium remain. Thus, theAgency believes that the prudent courseis to regulate total chromiumconcentrations under the TC. It shouldbe noted that because of this, theAgency is considering proposing thedeletion of the exclusion for specificchromium wastes that contain virtuallyno hexavalent chromium [see 40 CFR261.4(b)(6)[i)]. Such a change wouldaffect certain wastes from the leathertanning and finishing industry (as wellas certain sludges from the productionof TiO2 pigment using chromium-bearingores by the chloride process).

c. Nickel and Thallium. Severalcommenters expressed support forincorporating nickel and thallium intothe list of TC analytes. One commenteremphasized that unless such a step istaken, a major inequity will continue toexist in the regulation of listed andunlisted wastes that contain comparablelevels of nickel. Many othercommenters, however, objected to theinclusion of nickel and thallium in theTC. Most of these commenters doubtedwhether either element poses a threat tohuman health and the environment,noting that neither one is on the Primaryor Secondary Drinking Water Standardslist.



EPA has decided not to add moremetals to the TC constituent list at thistime because technical issues remain asto their subsurface fate and transport.The regulatory levels for the toxicitycharacteristic metals are not changed inthis rule (i.e., EPA is retaining theregulatory levels set under the previousEP) pending further Agency validationand study of the fate and transport ofmetals. These validation and studyefforts are focusing on the developmentof the metal speciation model(MINTEQ).

The Agency is developing MINTEQfor the evaluation of the mobility ofarsenic, barium, cadmium, chromium,lead, mercury, nickel, selenium, silver,and thallium in ground water. Amodified version of MINTEQ will beused in combination with a set ofgeneric ground water specifications andsubsurface conditions to determinemetal solubility limitations. EPA willthen use these results, in conjunctionwith the subsurface fate and transportmodel, to estimate dilution duringtransport to the down-gradient exposurepoint. (See discussion of thedevelopment of the subsurface fate andtransport of metals at 51 FR 1653,January 14, 1986.) The Agency is notspecifically proposing an approach forevaluating the fate and transport ofmetals in today's rule, but does expectto propose, at a later time, DAFs specificto metals, including nickel and thallium,and will address comments relating tothe toxicity of nickel and thallium atthat time.

C. Chronic Toxicity Reference Levels.The Agency proposed to use chronictoxicity reference levels (combined withDAFs) to calculate leachateconcentration limits for individualconstituents; a waste containingconstituents equal to or above thoselevels would be a hazardous wasteunder the TC. Specifically, EPAproposed to use the MCLs promulgatedas part of the National Interim PrimaryDrinking Water Standard (NIPDWS),where available, as the starting point forestablishing the regulatory levels foreach of the constituents. For thoseconstituents for which no MCLs hadbeen promulgated, the Agency proposedto use oral Reference Doses (RfDs) andRisk-Specific Doses (RSDs) to developchronic toxicity reference levels for thenoncarcinogens and carcinogens,respectively. Because exposure to toxicconstituents can occur by multiplepathways, the Agency also proposed toapportion the acceptable health risklevel of each noncarcinogenicconstituent among the various possibleroutes of exposure. The Agency solicited

public comment on: (1) Whether RfDsand RSDs are appropriate to use whenMCLs are available; (2) the health levelsproposed for RfDs and RSDs; (3) theassociated risk levels; and (4) theassumptions used to apportion exposureto the different possible routes. TheAgency's decisions regarding the health-related issues for which it solicitedcomments are presented below.

1. Maximum Contaminant Levels

The original toxicity characteristic-the EPTC (40 CFR 261.24)-used theNIPDWS developed under the SafeDrinking Water Act as the toxicitylevels to derive the regulatory levels forthe eight metals, four insecticides, andtwo herbicides then regulated. (For easeof discussion, the acronym "MCLs" willbe used in subsequent sections to refercollectively to both MCLs and theexisting NIPDWS.) EPA plans tocontinue this approach in the expandedTC for those constituents for whichMCLs are available.

A number of commenters expressedsupport for the use of MCLs, when theyexist, as the starting point forcalculating regulatory levels for the TC.Most of these commenters argued thatthe MCLs provide adequate protectionof human health. These commentersstated that MCLs are reliable,scientifically defensible, and recognizedand understood by the general public.

Several commenters supported the useof MCLs because factors relating to costand available treatment technology maybe considered along with health effectsin the development of the standards.These commenters asserted that MCLsrepresent a reasonable balance amongthe factors EPA must consider, whileRfDs and RSDs are more limited. Anumber of commenters also felt that theuse of MCLs provides a level ofprotection consistent with otherregulatory programs.

In contrast, other commenterssupported the use of RfDs and RSDs asthe basis for the chronic toxicityreference levels even when MCLs areavailable for those constituents. Thesecommenters stated that health-basedlevels are an appropriate starting pointfor the regulation. Because the MCLsconsider other factors relating totechnical and economic feasibility inaddition to toxicity, they contend thatthe RfDs and RSDs are preferable. Manyof these commenters also supported aconsistent approach for all constituentsregulated by the TC, rather than usingMCLs for some and RfDs and RSDs forothers.

Several commenters asserted thatbecause the MCLs were developed forthe purpose of regulating the

concentrations of constituents in treatedwater "at the tap," it is not appropriateto use the same standards for defininghazardous wastes. Several commentersalso expressed concern that the MCLsdeveloped under the Safe DrinkingWaterAct are potentially more stringentthan RfDs and RSDs. This concern wasmost strongly expressed regardingcarcinogens, for which MaximumContaminant Level Goals (MCLGs),previously referred to as RecommendedMaximum Contaminant Levels (RMCLs),are set at zero, and MCLs are set attechnically achievable levels that mostclosely approach this zero goal.

EPA maintains that the MCLs, whenthey exist, are the most appropriatehealth criterion to use as the startingpoint for developing the regulatorylevels. The exposure scenario developedfor the TC is based on ingestingcontaminated drinking water, andbecause MCLs are developed forregulation of drinking water, theyclearly are relevant. In addition, thedevelopment of the MCLs follows arigorous methodology in which allavailable health information isevaluated in establishing the MCLGs.The MCLs are set as close to the MCLGsas is feasible, and the Agency believesthat MCLs are protective of humanhealth.

It should be noted that EPA evaluatesthe health risks that are associated withvarious contaminant levels in order toinsure that the MCL adequately protectsthe public health. For drinking watercontaminants, EPA sets a reference riskrange for carcinogens at 10-4 to 10-6excess individual risk from lifetimeexposure. Most regulatory actions in avariety of EPA programs have generallytargeted this range using conservativemodels which are not likely tounderestimate the risk. Since theunderlying goal of the Safe DrinkingWater Act is to protect the public fromadverse effects due to drinking watercontaminants, EPA seeks to insure thatthe health risks associated with MCLsfor carcinogenic contaminants are in thegeneral range of 10-4 to 10- .

EPA acknowledges that use of MCLswill, in some cases, result in chronictoxicity reference levels that are lowerthan those that would be calculatedusing the RfD methodology. Forexample, many of the non-carcinogeniccompounds have MCLs which areapproximately 10 to 20 percent of theirrespective RfDs because exposuresources other than contaminateddrinking water are considered in settingthe MCLs. On the other hand, the MCLsfor some of the constituents addressedin the proposal are higher than the

11813



levels that would be calculated using theRSD methodology. An example of thissituation arises when the health criteriaare at such low levels that analyticalmethods are not available to measurethese levels. In cases where the MCL ishigher than a purely health-based level,the Agency notes that use of the MCL isnot inconsistent with today's rule sincethe purpose of the rule is to identifywastes that clearly pose hazards, not toidentify the lowest level of hazard.However, regardless of whether they arehigher or lower than the levelscalculated using the RfD or RSDmethodologies, EPA believes that MCLsare the appropriate starting point fordeveloping regulatory levels for the TC.

For the constituents lacking MCLs,EPA must rely on the availablemethodologies to provide chronictoxicity reference levels that arescientifically defensible and protectiveof human health. EPA believes that theRfD and RSD methodologies meet thesetwo criteria. EPA also realizes thatinconsistencies will exist when differentmethodologies are employed fordeveloping regulatory levels. TheAgency intends to evaluate newlypromulgated MCLs to determine on acase-by-case basis whether the TCregulatory level will change significantlyif the new MCL is used, and to revise theregulatory levels, as appropriate. In thelong run, this should provide internalconsistency for the TC, as well asconsistency with other regulatoryprograms.

Some commenters supported the useof MCLGs as the basis for chronictoxicity reference levels under the TCbecause the MCLGs are based on healtheffects alone, whereas the MCLsconsider other factors as well, such aseconomic and technical feasibility.

EPA disagrees with the commenterswho stated that MCLGs are moreappropriate than MCLs for use in theTC. MCLGs are nonenforceable healthgoals for drinking water, which are to beset at levels that would result in noknown or anticipated adverse healtheffects with an adequate margin ofsafety. The Agency has adopted thepolicy of setting the MCLGs for probablehuman carcinogens (Group A and Bcarcinogens) at zero. If the Agency wereto use MCLGs rather than MCLs in theTC, the regulatory levels for defining awaste as hazardous would be based onhealth criteria that, at least forcarcinogens, are more stringent than thecriteria used to set concentrationsacceptable' for direct human ingestion ofdrinking water. In addition, theregulatory levels would be virtuallyimpossible to detect analytically. This

would mean that any waste thatcontains detectable levels ofcarcinogens would be hazardousregardless of the potency of thecarcinogen or the risk presented by thatwaste. EPA believes that this is aninappropriate approach for the TCbecause it would result in the regulationof wastes which are not necessarilyhazardous.

2. Risk-Specific Doses for CarcinogenicConstituents

For constituents for which no MCLshave been established, EPA uses oralRSDs to develop chronic toxicityreference levels for carcinogens. TheRSD is an upper-bound estimate of theaverage daily dose of a carcinogenicsubstance that corresponds to aspecified excess cancer risk for lifetimeexposure. A predetermined risk leveland the oral carcinogenic, slope factorestimated by EPA's Carcinogen RiskAssessment Verification Endeavor(CRAVE) Workgroup or CarcinogenAssessment Group (CAG) are used tocalculate the RSD.

The Agency proposed a risk level ofconcern based on the weight of evidenceregarding carcinogenicity of eachconstituent. Constituents classified asknown or probable human carcinogens(Group A or B) were assigned a risklevel of 1 in 100,000 (i.e., 10-), whileconstituents classified as possiblehuman carcinogens (Group C) wereassigned a risk level of 1 in 10,000 (i.e.,10-4).

The Agency received commentsregarding both the weight-of-evidenceapproach for establishing risk levels andthe risk levels selected. In particular,one commenter supported the Agency'sproposal, stating that a single risk levelis not appropriate for all constituents,and that use of the weight-of-evidenceapproach avoids making regulatorydecisions based on insufficient data.Another commenter also supported theuse of weight-of-evidence to assign risklevels, but stated that it is inappropriateto regulate both known and probablehuman carcinogens at the same level ofrisk. Alternatively, a third commenterasserted that the weight-of-evidenceapproach is inappropriate because (1)new information is constantly beingdeveloped on the health effects of toxicconstituents, so the weight of evidenceis constantly changing, and (2) theclassification scheme does not take intoaccount the potency of the carcinogenicrisk

The Agency also received specificcomments regarding both the weight-of-evidence approach and the selection ofspecific risk levels. Several commentersaddressed the risk level at which the

Agency proposed to regulatecarcinogens. Some commentersspecifically expressed support for EPA'sproposal to regulate Class A and Bconstituents at a 10-S risk level andClass C constituents at a 10 - 4 risk level.One commenter stated that because theprocedure for developing risk estimatesis extremely conservative, the proposedrisk levels would not adversely affecthuman health and the environment.Another commenter noted that thestated risk levels are estimates of theupper confidence bound of risk and notthe maximum likelihood estimate; thus,the actual risk to the public would beless than the stated level.

Other commenters supported the useof a 10 - 6 risk level for all carcinogens.These commenters argued that the useof the proposed risk levels represents aserious weakening in EPA's regulationof carcinogens and is inconsistent withother policies in effect in other EPAprograms.

With respect to the weight-of-evidence approach, the Agency hasdecided to establish a single risk level ofconcern for all potential carcinogens(i.e., the Agency will not assign aspecific risk level to a specific weight-of-evidence carcinogenicity classificationfor this rulemaking). The weight-of-evidence approach for classifying aconstituent as carcinogenic is basedprimarily on the amount and quality ofdata that are available rather than thestrength of the toxic response in animalsor humans. In effect, it is a qualitativeassessment that takes into account theuncertainty in the data for determiningwhether an agent is carcinogenic tohumans. This means that the actualquantitative difference in risk betweenan "A" and "B" carcinogen as classifiedby the weight of evidence may either bezero or may be orders of magnitude.Thus, EPA believes that both the weight-of-evidence and the strength of the toxicresponse (i.e., potency) should beconsidered in making regulatorydecisions within the context of the TC.

With regard to the specific risk levelchosen, the Agency has decided to setthe level for carcinogens (Groups A, B,and C) at 1 in 100,000 (i.e., 10- 5) for thefinal rulemaking. Characteristics areestablished at levels at which theAgency hs a very. high level ofcertainty that a waste which exhibitsthese properties needs to be managed ina controlled manner (i.e., as a hazardouswaste). The Agency realizes that not allwastes which exhibit properties atconcentrations below the regulatorylevels are necessarily safe for disposalas nonhazardous wastes. Rather, thosewastes having properties lower than the



regulatory levels and which aredemonstrated to pose a hazard tohuman health or the environment stillremain subject to waste-specificevaluations under the hazardous wastelisting program. Wastes which aredetermined to require controlledmanagement after consideration of thefactors identified in 40 CFR 261.11(a)(3)(e.g.i the nature of the toxic constituents,toxicant mobility under variousenvironmental management scenarios,volume of waste generated and potentialmethod of management) are thenspecifically listed as hazardous wastesand subjected to the appropriate RCRAmanagement controls. This reflectsEPA's philosophy, first articulated inMay of 1980, that the characteristicdefines broad classes of wastes that areclearly hazardous, while the listingprocess defines some wastes that maynot exhibit the characteristics but arenonetheless hazardous wastes (45 FR33111, May 19,1980).

The chosen risk level of 10- is at themidpoint of the reference risk range forcarcinogens (10-4 to 10- 9 targeted insetting MCLs. This risk level also lieswithin the reference risk range (10-4 to10-9 generally used to evaluateCERCLA actions. Furthermore, bysetting the risk level at 10- 5 for TCcarcinogens, EPA believes that this isthe highest risk level that is likely to beexperienced, and most if not all risk willbe below this level due to the generallyconservative nature of the exposurescenario and the underlying healthcriteria. For these reasons, the Agencyregards a 10 - 5 risk level for Group A, B,and C carcinogens as adequate todelineate, under the TC, wastes thatclearly pose a hazard whenmismanaged.

3. Apportionment of Health Limits

EPA proposed to account for potentialexposure from sources other than the TCscenario by apportioning the RfD-basedchronic toxicity reference levels. Theapportionment scheme effectivelyreduced each such chronic toxicityreference level to 50 percent of itsoriginal value, (i.e., 50 percent of theRfD). The Agency also proposed toestimate environmental partitioning ofthe apportioned health limits in air andwater according to a simplifiedfractionation scheme using Henry's LawConstants (-IH) and octanol-watercoefficients (K..] for individualconstituents. The Agency did notpropose to apportion the chronic toxicityreference levels based on RSDs orMCLs.

Several commenters addressed theAgency's proposal to apportion theRIDs. Commenters that criticized the

Agency's proposed apportionmentscheme argued that it was arbitrary,overly conservative, and unnecessary.Several commenters recommended thatEPA either use more realistic estimatesof exposure based on the availableconstituent-specific data or notapportion at all.

After a review of comments on theproposed regulation and considerationof the available data, the Agency hasdecided not to apportion in thisrulemaking. Although the concept ofapportionment has some scientific basisin that individuals are exposed to manyof the chemicals of concern throughmore than one route of exposure andfrom more than one source, theimplementation of the concept is verydifficult when adequate data on theamount of exposure and/or healtheffects from all routes of exposure donot exist. Thus, due to the lack ofsufficient data to determine anappropriate apportionment factor for thevarious constituents, the Agency nowconcludes that its proposedapportionment scheme cannot besupported at the present time. Of course,the proposed apportionment would d~alwith uncertainty by erring on the side ofsafety; nevertheless the Agency believesthat the conservative approach used todeal with uncertainty in thedevelopment of the RfD is sufficientlystringent to define those wastes thatclearly pose hazards. This approach isin accordance with the Agency'streatment of noncarcinogens. TheAgency therefore will not apportion theRfDs for this rulemaking.

A few commenters criticized theAgency's proposed method forfractionating the apportioned RIDbetween air and water. Thesecommenters questioned the technicalbasis of the Agency's approach and/orrecommended alternative schemes. TheAgency agrees with commenters that thetechnical basis for supportingfractionation as proposed is inadequateto predict media-specific concentrations.The Agency is exploring thedevelopment of an appropriate model.Thus, EPA has decided not to apportionthe RID and not to fractionate the RIDbetween air and water in thisrulemaking.

Other commenters addressed theapportionment of RSDs for carcinogenicconstituents. Several of thesecommenters agreed with EPA's decisionnot to apportion RSDs, stating that doingso would result in very low regulatorythresholds for some constituents. Thecommenters also pointed out that manyconservative assumptions are alreadyincorporated into the development of the

RSDs for carcinogens. Otherscommented that RSDs should beapportioned because humans areexposed to these constituents bymultiple routes.

The Agency continues to believe thatit is not appropriate to apportion theRSDs for carcinogenic constituents.RSDs are estimated by a procedure thatmust deal with unavoidableuncertainties and is thereforeintentionally conservative. The Agencystated in the preamble to the proposedrule that a difference in dose of a factorof 2 is still well within the margin ofuncertainty of the estimated RSD (51 FR21667, June 13, 1986).

Table C-1 presents chronic toxicityreference levels for the constituents intoday's rule. The Agency received anumber of comments on specific chronictoxicity reference levels. In some cases,EPA responded to these comments inthe notice of proposed changes to thehealth levels on May 19, 1988 (53 FR18024). Other chemical specificcomments are addressed in thebackground document (Ref. 3).

TABLE C-1.-CHRONIC ToxICITYREFERENCE LEVELS

Chronictoxicity

Constituent reference Basislevel (mg/ I

)

Arsenic ........................................Barium .........................................Benzene . ......................Cadm ium ..................... ...........Carbon tetrachloride .............Chiordane ...................................Chlorobenzene ...........................Chloroform .................................Chrom ium .................................o-Cresol ................................m -Cresol ......................... ...........p-Cresol .......................................2,4-D ............................................1,4-Dichlorobenzene ..............1,2-Dichloroethane .................1,1-Dichloroethylene ..................2,4-Dinitrotoluene .......................Endrin ..........................................Heptachlor (and its hydrox-

ide).Hexachlorobenzene ...................Hexachloro-1,3-butadiene.Hexachloroethane ......................Lead .............................................Lindane .......................................M ercury .......................................M ethoxychlor ..............................M ethyl ethyl ketone ...................Nitrobenzene ..............................Pentachlorophenol ...............Pyridine .......................................Selenium .....................................Silver ...........................................Tetrachloroethylene ..................Toxaphene ..................................Trichloroethytene ......................2,4,5-Trichloropheno .................2,4,6-Thchlorophenol .................2,4,5-TP acid JSilvex) ................

0.051.00.0050.010.0050.00031

0.060.052220.10.0750.0050.0070.00050.00020.00008

0.00020.0050.030.050.0040.0020.120.021

0.040.010.050.0070.0050.00540.020.01



TABLE C-1 .- CHRONIC TOXICITYREFERENCE LEVELS-Continued

Chronic Itoxicity I

Constituent reference Basislevel (mg/

___________________ L) ___

Vinyl chloride .............................. 0.002 MCL

All RSDs are calculated at the 10- 3 risk level.

D. Use of Generic Dilution/AttenuationFactors (DAFs)

In the May 19, 1988 supplementalproposal, EPA requested comment on analternative strategy for setting DAFs inthe TC. The alternative involved settingDAFs for these constituents in twophases. The first phase would use ageneric DAF in a manner similar to theexisting EPTC, which uses a DAF of 100for all EP constituents. In the secondphase, the Agency would furtheraddress the manner in which the DAFsare calculated and would either: (1)Continue to use generic DAFs, (2)employ a subsurface fate and transportmodel to develop constituent-specificDAFs, or (3) use some combination ofthe two approaches. The Agency alsospecifically solicited comment on theuse of a generic DAF of 100 or 500 in thefirst phase.

Many commenters recognized theneed to expeditiously promulgate theTC; however, most opposed the two-phased approach, arguing that it wouldcause undue economic burden by: (1)Forcing industries to design newtreatment programs for one group ofwastes at certain regulatory levels, anda few years later to redesign in order toaccommodate new levels and wastes,and (2) over-regulating certain chemicalsubstances under the first generic-DAFphase that may then not be regulatedunder the second phase. Somecommenters were concerned, on theother hand, that EPA would set thegeneric DAFs so high (to avoid

overregulation) that some substanceswould be under-regulated.

Most commenters opposed the use ofgeneric DAFs and urged EPA to retainthe constituent-specific modelingapproach. These commenters arguedthat a generic DAF would be arbitraryand not scientifically defensible; thatuse of the generic DAFs would violatethe statutory requirements to develop aprocess that accurately assessesleaching ability and differentiatesbetween hazardous and nonhazardouswastes; and that the diversity in dilutionand attenuation attributes across theconstituents would cause any genericDAF to either severely under-regulate orseverely overregulate a large number ofthe constituents. Even those fewcommenters who supported the two-phased approach recommended that theAgency move rapidly to the secondphase and employ the modelingapproach to set DAFs.

EPA acknowledges that the problemsnoted by the commenters are importantones. The Agency requested commenton the generic DAF approach because ofthe likelihood that the issues,surrounding the proposed fate andtransport model for establishingconstituent-specific DAFs would not beresolved in a timely manner. Since theAgency has been able to address theconcerns regarding the subsurface fateand transport model for the constituentsidentified in today's regulation, theAgency has decided to use the model todevelop DAFs. Consequently, the DAFsset in today's rule for nonhydrolyzingconstituents for which the steady-statesolution is appropriate are not viewedby EPA as interim and are supported bythe subsurface fate and transport model.The Agency intends to establish DAFsfor constituents not addressed in today'srule on a constituent-specific basis, andregulatory levels for those constituentswill be proposed or promulgated (aswarranted) at a later date.

E. Application of a Subsurface Fate andTransport Model

1. Introduction

On June 13, 1986, EPA proposed anapproach (see 51 FR 21648) forestimating regulatory concentrationlevels in a waste leachate using chronictoxicity reference levels, combined withconstituent-specific dilution/attenuationfactors (DAFs) derived from theapplication of a subsurface fate andtransport model. The model(EPASMOD) was first described forpublic comment on January 14, 1986 (51FR 1602).

A DAF represents a reduction in theconcentration of a constituent expectedto occur during transport through groundwater from the bottom of a disposal unitto a drinking-water source. In responseto the proposal and supplementalnotices (see Section II, Table 11.1), theAgency received numerous commentson the subsurface fate and transportmodel used for the calculation of DAFs.This section describes the differentproposals related to the use of thesubsurface fate and transport model, themodifications to the model in responseto public comments, and the resultsobtained with the use of the modifiedmodel.

a. June 13, 1986 Proposed Rule (51 FR21648). The Agency's June 13, 1986proposal used a subsurface fate andtransport model (EPASMOD) tocalculate specific DAFs for each of the44 organic hazardous constituents (seeTable E-1). The DAFs for eachconstituent were calculated using themodel, incorporating compound-specifichydrolysis and soil adsorption datacoupled with parameters describing thesubsurface environment (e.g., groundwater flow rate, hydraulic conductivityof the aquifer, ground water pH, etc.).The Agency proposed modeling ascenario of waste mismanagement at asubtitle D municipal landfill. Data wereincorporated in the model using a montecarlo simulation.

TABLE E-1.-DILUTION ATTENUATION FACTORS FOR TOXICITY CHARACTERISTIC ORGANIC CONSTITUENTS

Constituent LOG f Ka 2 Kb

2 Kn 2 D/A

Kow [ I I factor 3

Acrylonitrile .....................................................................................................................Benzene ..................................................................................................................Bis(2-chloroethyl)ether ..................................................................................................Carbon disulfide ............................................................................................................Carbon tetrachloride .....................................................................................................Chlordane .......................................................................................................................Chlorobenzene .......................................................................................................Chloroform ...............................................................................................................o-Cresol .................................................................................................................m -Cresol ..................................................................................................................p-Cresol .........................................................................................................................2,4-D .... .............................................1,2-Dichlorobenzene .......................................................................................... .

0.072.131.042.162.965.482.871.962.152.152.152.703.56

> 1/yr .......................NHYF 4 ...............

......NH 5 ..........................NH .............................NH .............................NH .............................NH .............................NH .............................NHYF ........................NHYF ........................NHYF ........................NHYF ........................NH .............................

> 1/yr .......................NHYF ........................NH ....... ..............> 10/yr .....................NH .............................> 10/yr .....................1E-6/hr .. : .....0.23/hr ......................NHYF ........................NHYF........................NHYF ........................NHYF ........................1E-5/hr ....................

> 1/yr ......................NHYF ........................8E-5/hr ....................NH .............................NH .............................NH .............................NH .............................3E-9/hr ....................NHYF ........................NHYF ........................NHYF........................NHYF ......................N H . . .............


Federal Register / Vol. 55, No. 61 / Thursday. March 29, 1990 / Rules and Regulations 11817

TABLE E-1 .- DILUTION ATTENUATION FACTORS FOR TOXICITY CHARACTERISTIC ORGANIC CONSTITUENTS-Continued

LOG K. Kb2 Kn 2 D/AConstituent Kow K factor 3

1,4-Dichlorobenzene ................................................................................................... 3.56 NLFG 6 .................... NLFG ....................... NLFG ........................ 14.41,2-Dichloroethane ................................................. ? ............................................. . 1.40 NH ............................ NH ............................. 7.2E-5/hr ................. 75.01, 1 -Dichloroethylene .... . ........... ..... .... ... ................................................. . . ......... 2.13 NLFG ............. :........... NLFG ............ . ......... N LFG ........................ 14.4

2,4 - in itro to lu en e. ...... . . ................................. .... ... 2.30 NLFG ........................ NLFG ....................... NLFG ........................ 14.4

Endrin ...................................................................................................................... 73.54 >1/yr ....................... >1 /yr ..................... >/yr ...................... 14.4

Heptachlor (and its hydroxide) .................................................................... 74.61 NLFG ........................ NLFG ...................... N LFG ....................... 14.4Hexachlorobenzene .................................................................................................... 6.42 <1/yr ....................... <i/yr ....................... <1 /yr ....................... 14.4Hexachlorobuta diene ................ ................................................................................ 4.24 NLFG ........................ NLFG ........................ NLFG ........................ 14.4

Hexachloroethane ..................................................................................................... 4.22 >1/yr ....................... >1 /yr ..................... > 1/yr ....................... 14.4Isobutanol .... ................................................................................................................ 0.74 > 1/yr ....................... > l/yr ....................... > llyr ....................... 14.4

Undane .......................................................................................................................... 3.40 >1/yr ....................... > 1/yr ....................... > 1/yr ...................... 14.4Methoxychlor ................................................................................................................. . 74.30 NH ............................. 1.4/hr ....................... 7.5E-5/hr ................. 14.4Methylene chloride ......................................................................... ........................ 1.26 NH ............................. NH ............................. 1.18E-8/hr ............... 14.4M ethyl ethyl ketone ............................................. . ............................................... 0.30 N LFG .......... NLFG ...................... NLFG ....................... 14.4

Nitrobenzene ............. ........................................................................... ........ ....... 1.90 NLFG ........................ N LFG ....................... NLFG ...................... 14.4Pentachloro phenol .... .................................................................................... . ............ 5.06 NH ............................. > 1E-4/hr ................ NH ........ .................... 14.4

Phenol ................................ . .. 1.49 N HYF ........................ NHYF ....................... NHYF ........................ 14.4Pyridine ........ . . ... . . . ....................... ..... .. 0.68 NLFG ........................ NLFG ........................ NLFG ........................ 14.4

1,1, 2-Tetrachloroethane .................................................................................... 2.81 NH ............................ 1.3/hr ........................ 2.2E-7/hr ................. 14.41,1,2,2-Tetrachloroe thane ............................................................................. .............. 2.42 NH ............................. 2.6E+ 3/hr ............. . NH ........ .................... 65.0

Tetrachloroethylene ..................................................................................................... 3.03 NLFG ........................ NLFG ........................ NLFG ........................ 14.42,3,4,6-Te . h orophenoI .......................................................................................... 4.33 N H ............................. 1E-5/hr .................... NH ............................ 14.4

Toluene .................................................................................................................... .2.82 NHYF ........................ NHYF ........................ NHYF ........................ 14.4Toxaphene ......... . .. . .. ... . .. ... ........................................................................ ......... 7 5.30. NH ............................. > 10/yr ..................... NH .............................. 14.4

1,1,1-Tdchloroethane .................................................................................................... 2.50 NH ............................. N H .................. 1.1E-4/hr ................. 150.01,1,2-Trichloroethane ................................................................................................... 1.91 NH ............................. 13/hr ......................... 4.3E-7/hr ................. 20.0Trichloroethylene .......................................................................................................... 2.28 NLFG ........................ NLFG ....................... N LFG ........................ 14.4

2,4,5-Trichlorophenol ............................................................................................... 3.86 NH ............................. 1E-5/hr .................... NH ............................. 14.4

2,4,6-Trichlorophenol ....................... . ....................................................................... 3.58 NH ............................ 1E-5/hr .................... N H ....................... .. 14.42,4,5-TP (Silvex) .......................................................................................................... 3.45 N LFG ........................ M FG ........................ NLFG ....................... 14.4

Vinyl chloride ................................................................................................................. 1.38 NH ............................. 1E-5/hr .................... IE-7/hr ................... . 14.4

Ln arithm of the octanol/water partition coefficient.2 Acid, base and neutral hydrolysis rate constants.2 Dilution/attenuation factor derived from ground water transport system.0 NHYF = No Hydrolyzable Functional Group.5 NH = Negligible Hydrolysis.• NLFG = No Liable Functional Group.'Estimated value.

In the monte carlo simulation, valuesfor each parameter-are based upon thefrequency distribution for eachparameter (where such data exists)rather than the selection of a singlevalue for each parameter. The model isthen run a sufficient number of times(typically several thousand) to producethe frequency distribution of the model'soutput. This overall frequencydistribution is, effectively, acombination of the frequencydistributions for each individualparameter. This approach avoids thecompounding effects of conservatisminherent in choosing single, reasonable-worst-case values for each parameter.Monte carlo simulation was chosen asthe preferred method to analyze the fullrange of possible environmentalconditions for the land disposalscenario. The wide range ofenvironmental conditions (e.g., groundwater velocities, pH, temperatures,exposure point locations) that can existin locations across the nation where thewastes in question may be disposedprecludes a priori specification of areasonable worst case for theseparameters. Another important reasonto use the mor te carlo method is the

very complex manner in which the manymodel variables and parametersinteract. Unless many (hundreds tothousands) combinations of variablesare investigated, it is simply not possibleto anticipate those physical settings thatlead to unacceptably high exposurelevels. Accordingly, the monte carlomethod was chosen to ensure that aconservative but not physicallyunrealistic or impossible analysis wascompleted.

The EPASMOD, as described in theproposed rule, was based on a numberof key assumptions pertaining to thefeatures of ground water flow,properties of the porous medium, andthe behavior of hazardous wastes inground water. These assumptionsincluded the following:

• Saturated soil conditions (noattenuation of chemicals in theunsaturated zone);

* Flow regions of infinite extent in thelongitudinal direction, semi-infiniteextent in the lateral direction, and finitein the vertical direction;

* Aquifer can be characterized byhomogeneous and isotropic propertiesand the aquifer thickness is constant;

9 Ground water flow is uniform andcontinuous in direction and velocity;

• Degradation is limited to hydrolysisand the by-products of hydrolysis areassumed to be nonhazardous;

* Contaminants follow a linearequilibrium adsorption isotherm;

e An infinite source supplies aconstant mass flux of chemical into theaquifer;

* Recharge due to precipitationsupplies water to the disposal unit andthe aquifer;

• The ground water upstream of thedisposal site is initially free ofcontamination;

• The receptor well is directly in linewith the source and the ground waterflow direction;

0 The receptor well is located 500 feetfrom the unit- and

* Hydraulic conductivity does notvary with temperature.

In the June proposed rule, the Agencyalso proposed using the 85th cumulativepercentile level of the back-calculateddilution attenuation factors obtainedusing the monte carlo simulationtechnique as an appropriate regulatorylevel for the TC. Selection of this levelmeans that downgradient



concentrations will not exceed theallowable health-based concentrationsin more, than 15 percent of all possibleanalyzed settings of subtitle D disposalunits. (This proposal referenced otherproposals dealing with the ground watertransport model, such as the January 14,1986 Land Disposal Restrictions notice,and notices published by the delistingprogram; relevant comments received inresponse to those notices are alsodiscussed in this rulemaking.)

b. August 1, 1988 Notice of DataAvailability and Request for Comments;Supplement to Proposed Rule (52 FR28892). On August 1, 1988, the Agencypresented new data related to subtitle Dmunicipal landfills, soil characteristics,and chemical-specific hydrolysis ratesto be used with the subsurface fate andtransport model to calculate DAFs foreach of the organic constituents in theTC. These new data became availableto the Agency after the June 13, 1986proposal. The August 1, 1988 Notice alsorequested comments on several majorrevisions to EPASMOD that were beingconsidered by the Agency, subsequentlyreferred to as EPA's Composite Modelfor Landfills (EPACML). As a result ofcomments received on the January 14,1986, and June 13, 1986 proposals, aswell as the August 1, 1988 Notice, theAgency has used EPACML to supportthe choice of appropriate DAFs for thisrulemaking.

These modifications and data aredescribed in greater detail below(section III.E.2). The reader is referred tothe Response-to-Comments BackgroundDocument for the Subsurface Fate andTransport Module (Ref. 1), whichpresents, in detail, each of the technicalissues addressed in the public commentson the model and the Agency's responseto these issues.

2. Modifications of the Subsurface Fateand Transport Model (EPASMOD) inResponse to Comments

In today's rule, the Agency has usedEPACML to estimate the attenuationand dilution of specific constituentsduring their migration through theunsaturated zone beneath a municipallandfill and their transport through thesaturated zone to a potential drinkingwvater source (exposure point). EPACML:iccounts for dispersion in theongitudinal, lateral, and verticallirections; one-dimensional steady and:iniform advective flow; sorption; and:hemical degradation from hydrolysis.fhe major enhancements that were:nade to EPASMOD to produce

PACML, the substantive comments'hat led to these changes, and importantassumptions made to develop analytical

solutions are described in subsection (a)below.

In addition, the Agency used theEPACML model to corroborate itsconclusions on dilution/attenuationfactors for surface impoundments. Forthis exercise, data inputs typical ofsurface impoundments rather thanlandfills were used. These proceduresare described in subsection (b) below.

a. General Modifications-i.Unsaturated Zone. The EPASMODmodel discussed in the June 13, 1986proposal assumed that there was nounsaturated zone (i.e., the bottom of thelandfill is directly connected to the topof the aquifer). Several commentersstated that the assumption that thefacility is located directly at the top ofthe saturated zone is unrealistic becausean unsaturated zone usually existsabove the aquifer and that retardation,dilution, and degradation effects in theunsaturated zone should be considered.The commenters also suggested that,when incorporating the unsaturatedzone, the depth to the water tableshould be incorporated as part of themonte carlo analysis.

The Agency is in agreement with thecommenters and has now included anunsaturated zone as part of thesubsurface model. The Agency believesthat this modification to the model isreasonable, based in part on a survey ofexisting municipal landfills thatindicated that an unsaturated zoneexists beneath 95 percent of thesurveyed landfills. Incorporating anunsaturated zone into the modelaccounts for any retardation anddegradation of chemicals in theunsaturated zone and provides-a morerealistic scenario.

To account for the unsaturated zone,the Agency developed unsaturated zoneflow and transport modules andimplemented them using the monte carlo(probabilistic) framework that hasalready been used in conjunction withthe saturated zone modeling approach inEPASMOD; these unsaturated zonemodules are incorporated into EPACML.The input concentration to theunsaturated zone transport module ofEPACML corresponds to the leachateconcentration at the bottom of thelandfill.

The unsaturated zone model wasreviewed by EPA's Science AdvisoryBoard (SAB). The SAB endorsed the useof the model for applications for thedevelopment of regulations; however,the SAB recommended that it not beused for site-specific applicationsbecause the model has limitationsimposed by the simplifying assumptions(those necessary for regulatory use), and

the limitations of the use of site-specificdata. The unsaturated zone modelconsists of two modules: a flowcomponent and solute transportcomponent. These two components weredeveloped in a form to allow for theirincorporation in the monte carlosimulation. The major assumptions andconsequences of the flow module are:

* Flow is steady in the verticaldirection, and lateral and transversemovement of the leachate is negligible.Because there is little or no lateral flowin the unsaturated zone, theseassumptions are appropriate. In anycase, this procedure will tend tomaximize the concentration of leachateleaving the unsaturated zone andtherefore represents a conservativeassumption,

* No vapor phase or immiscibleliquid flow occurs, and the water phaseis the only flowing material. EPAacknowledges that some constituents insome situations may undergo phaseshifts and be emitted in vapors. Becausethis rule is essentially directed to risksfrom drinking water and because of theuncertainties in accurately computingemissions and their relationship to thecurrently available leaching tests, thisconservative assumption was adopted.Under certain conditions, particularlyvery high constituent concentrations,immiscible liquid flow can occur. Forsuch situations, the model's inability toaccount for the immiscible flowcondition may lead to higherdowngradient concentrations (i.e., themodel would underestimate the receptorwell concentrations).

- Flow is isothermal (not affected bytemperature variations). In reality,temperature variations at any given siteare not dramatic because the source ofinfiltrating liquid is precipitation. Thus,this assumption is not expected toinfluence the results to any appreciabledegree.

9 Effects of variations in theunsaturated zone hydraulic propertiescaused by alternating moistureconditions are negligible (i.e., hysteresiseffects). Many soils, especially the moreporous ones for which infiltration ratesare high, do not present importanthysteresis effects. In other cases, littleand often no data are available tocharacterize the effects. Failure toinclude hysteresis is not expected toaffect the results to any appreciableextent.

- The flow field is uniform andcontinuous in direction and velocity.Precipitation-driven infiltration can be adynamic process where much of thevertical movement'occurs duringrelatively short periods of time. Time-



averaged values of infiltration derivedfrom dynamic water balancecalculations (as described in theBackground Technical SupportDocument) are often used to enablesolution of analytical, steady-flowmodels. The unsteady-flow conditionscould lead to higher downgradientconcentrations than predicted byEPACML. However, the effect isexpected to be significant only forrapidly degrading constituents. For theconstituents regulated in this rule, noappreciable impact is expected becausenone of the constituents are expected tohydrolyze to any significant extentduring transport.

- The unsaturated zone ishomogeneous and isotropic. Thisassumption is typically required toenable mathematical solutionsamenable to exhaustive sensitivityanalyses and monte carloimplementation. In any one application(one model run) of this assumption, theresult can either under- or over-predictdowngradient concentrations. Themonte carlo implementation, however,results in a very wide range of possibleconditions, and thus the total analysis,when taken together, accounts for awide variety of unsaturated zoneconditions.

The major assumptions andconsequences of the unsaturated zonetransport module are:

* Chemical transport is vertical;lateral and transverse movement of thechemical is negligible. This follows fromthe first assumption for the flow moduledescribed above.

• Chemical sorption is modeled as areversible, linear equilibrium process.This is a standard modeling assumptionwhich is accurate for systems havingrelatively low solute concentrations, andconservative at higher concentrations.

* Degradation is limited tohydrolysis. This assumption was madeto be consistent with the similarapproach adopted for the saturatedzone. Thus, the model includes onlythose degradation mechanisms that canbe reliably characterized in laboratorystudies of each individual constituent.This assumption remains a majorconservative component of the overallmodel.

e Chemical transport in the vaporphase has been assumed to benegligible. This follows from the secondassumption for the flow moduledescribed above.

* The unsaturated zone transportmodel is solved for the steady-statecondition. This is a conservativeassumption that has been investigatedfor its impact on all the originallyproposed constituents. The extent to

which this assumption is appropriate isdiscussed in section III.E.4(b)(iii).

The details of the unsaturated zonemodule are provided in the backgrounddocuments (Ref. 1, 9), which alsodescribe the data sources and analysesthat were performed to obtain the datadistributions.,

i. Source Characterization. InEPASMOD, the input leachate to thesaturated zone was assumed to beinstantaneously mixed in the verticaldirection over a pre-specified depth ofsource penetration, and theconcentration in the leachate was equalto the maximum source contaminantconcentration in the saturated zonebelow the facility. Mass balanceconsiderations required that the lateralextent of the leachate directlyunderneath the facility be adjusted toensure that leachate was neither gainednor lost in the transition from the facility(or unsaturated zone) to the aquifer. Anumber of commenters criticized thetreatment of the source. A majorconcern was that the method wasinadequate because of an overlyconservative assumption, which equatedthe concentration of the contaminant inthe saturated zone to the landfillleachate concentration. Thus,commenters argued that EPA had notgiven adequate consideration to mixingand dispersion under the landfill. Thecommenters also pointed out that thistreatment of the source could result inmodeling physically unrealisticboundary conditions (e.g., by modeling asource of small cross-sectional area witha very large width of the Gaussiansource, and vice versa).

The Agency agrees with thecommenters that the method used tocharacterize the source-boundaryconditions for the saturated zonetransport needed to be improved. Thus,the method has been revised to considerthe mass balance requirements,geometrical configurations, and physicalprocesses that are occurring in themixing zone below the facility andwithin the saturated zone. An importantcharacteristic of the revised method isthe plume restriction in the lateralextent. That is, the method no longerpermits physically unrealistic situationswhere the plume source width exceedsthe facility width. In addition, thecurrent method of computing the source-boundary conditions represents themixing and dilution effect on theleachate below the source and ensuresthat the concentration of thecontaminant in the saturated zone willbe less than or equal to the landfillleachate concentration.

iii. Treatment of Dilution fromRecharge. In EPASMOD, the dilution

effect of ground water recharge oncontaminant transport in the saturatedzone was taken into account byincluding recharge as a dilution term inthe governing equation. Dilution ofleachate concentrations from rechargewas calculated by dividing theinfiltration (recharge) rate by the source.enetration depth. A number ofcommenters were concerned that theinfluence of recharge on the groundwater flow field had not been properlyaccounted for in the model. In addition,several commenters alerted the Agencyto an error in the equation used toevaluate the recharge dilutionparameter.

In response to these comments, theAgency has modified the model tocalculate dilution from recharge bydividing the recharge rate by the totalsaturated thickness of the aquifer, theaquifer porosity, and the effectiveretardation factor in this zone. Thisrevision represents a more realisticassessment of the dilution potential ofrecharge by considering changes in theentire volume of water in thecontaminated aquifer and theeffectiveness of contaminant andrecharge flow and mixing in the aquifer.

The Agency recognizes that rechargeeffects on ground water flow fields arenot rigorously considered in the modeland that the assumption of uniform,constant, horizontal ground watervelocity neglects the possible effects oflocal mounding of the water tableunderneath the land disposal unit.However, the constant velocityassumption can be interpreted as anaveraging of the velocity field over thespatial area affected by recharge; inaddition, the uniform, horizontal flowassumption was necessary to make thethree-dimensional transport equationanalytically solvable. The effect ofrecharge on ground water velocity isdifficult to account for directly in themodel. To assist in the analysis, EPAhas conducted a sensitivity analysiscomparing EPACML results withrecharge effects as predicted by a two-dimensional numerical model thatrigorously accounts for recharge. Theresults (which can be found in Ref. 9)indicated that as long as recharge valuesare significantly less than the naturalflow velocity, there was no major effecton the ground water flow fields. Basedon this analysis, and on evidence oftypically low rates of ground waterrecharge, the Agency believes that therevised treatment of the dilution effectfrom recharge is reasonable. In addition,the error, as pointed out by severalcommenters, in the equation used toevaluate the recharge dilution


11820 Federal Register /'Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

parameters was corrected, and thecorrection is included in EPACML.

iv. Location of the Receptor Well. InEPASMOD, the receptor well wasassumed to be located downgradientfrom the landfill along the centerline ofthe plume (direction of ground water-flow) at a fixed distance of 500 feet[152.4 in). In addition, the receptor wellwas assumed to be tapping water fromthe top of the aquifer, and no mixing ofwater in the well or effects of drawdownin the well were considered inEPASMOD.

Many commenters argued that theassumptions concerning the location ofthe receptor well were too conservativeand suggested that well locations should

be considered in a probabilistic manneras part of the monte carlo simulation inthe model. These commenters noted thatwell locations other than on thecenterline should be considered. Severalcommenters also stated that the welllocations should not be restricted tolying within the areal extent of theplume and suggested that wells locatedoutside of the plume should beconsidered in the calculation of thedilution/attenuation factors.

The Agency agrees that the proposedlocation of the well was unrealistic andthat affected wells located at pointsother than on the centerline should beconsidered. Therefore, the model nowconsiders well locations anywhere

within the areal extent of thecontaminant plume. In order toincorporate these locations, adistribution of distances todowngradient wells was developedbased upon a subtitle D municipallandfill survey (Ref. 6). These distanceswere used as part of the monte carloanalysis. Also, to incorporate locationsother than on the centerline, the Yvalues (see Figure 1) were selectedrandomly over a 180* domain but the X-Y pairs were constrained to values thatwere located within the areal extent ofthe plume.BILLING CODE 65W)-6"-.


Federal Register I Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations 11821

FIGURE 1

A SCHEMATIC OF THE WASTE FACILITY SOURCE BOUNDARYCONDITION AND LEACHATE MIGRATION THROUGH THE

UNSATURATED AND SATURATED ZONE

PLANLVIEW

": "Monitoring Well r:-.

WasteT X~l: T7: : : :...F a cility w l :i : .. . : .

L____________L. contminant Plume!..::;

SECTION VIEWMonitoring

Unsaturated Zone

BILLING CODE 6560-50-C



The Agency disagrees with thosecommenters who stated that welllocations outside of the areal extent ofthe plume should be considered. Thepurpose of the Toxicity Characteristic isto answer the question "if themanagement of this waste continues tobe uncontrolled, what are theconsequences in terms of humanexposure via ingestion of contaminateddrinking water?" In performing theexposure assessment to answer thisquestion, the Agency believes itappropriate to consider only wells thatcould be affected by the disposal of thewaste. Wells that could not be affectedby the migration of constituents from thewastes are obviously irrelevant to theexposure assessment and, thus, notconsidered.

C6mmenters also stated that it wasunrealistic to assume that the welltapped water from only the uppermostpoint of the aquifer. These commentersstated that, in practice, the intakeportion of a well is located below thetop of the water table and that mixingand drawdown will occur.

The Agency agrees that the proposedwell intake location was unrealistic andthat it ignored the effects of verticalmixing and the possibility that the wellintake would likely be at some pointother than the top of the aquifer. Inresponse, the assumption has beenmodified to consider well intake at anypoint throughout the depth of theaquifer. This modification largely takesinto account the above-described mixingand drawdown effects.

In determining how to account forwell drawdown more realistically in themodel, the Agency considered themechanics of well construction.Generally, wells are screened from nearthe top of the aquifer to a sufficientdepth (into the aquifer) to allow deliveryof the needed water supply. Thus, theranges of values for the length of thescreens and their locations relative tothe top of the aquifer are very large. Inrecognition of this variability, especiallyin screen length, the Agency hasemployed a simplifying assumption thatthe concentrations of constituents atvarious depths of the aquifer representthe concentrations at the exposurepoint. That is, the concentration ofconstituents in the water drawn fromthe well is assumed to be equal to theconcentration of the constituents at thedepth which is selected in the montecarlo simulation. (The well depth israndomly selected from all points withinthe vertical range of the aquifer'sthickness.)

To evaluate the model's sensitivity tothis assumption, the Agency evaluatedthe case in which wells were assumed to

be screened from the top of the aquiferto the monte-carlo-selected depth. Theexposure point concentration was thencalculated as the average concentrationover the screened depth. This case isconsidered to be more representative ofthe most likely well design, although inmany cases the well will not extend tothe bottom of the aquifer nor will italways be constrained to intersect theplume as is implemented in the montecarlo simulation. This scenario isconsidered to be more conservative (i.e.,resulting in lower DAFs) than theEPACML-as-implemented scenario.When one considers other possibilitieslike well location factors up gradientand outside the plume, the range ofDAFs from the two scenarios can beexpected to bound the actual exposures.

In evaluating the model predictionsover the range of cumulative frequencyvalues. considered in interpreting themodel's results in today's rule (seeSection III.E.4--DAF Evaluation), thedilution/attenuation factors for the twoscenarios are not sufficiently different towarrant separate conclusions regardingthe appropriate value for use in today'srule. (Model results for the twoscenarios are compared in thebackground document for the model-Ref. 9.)

v. Dispersivity Values. Dispersivitycontrols the degree of spreading ofdissolved contaminants in thesubsurface. The saturated-zone fate andtransport model includes dispersion inthe longitudinal, transverse (horizontal),and vertical directions. The model thusrequires values of the longitudinal,transverse, and vertical dispersivities inthe saturated zone. In EPASMOD, thedistance x from the downgradient edgeof the landfill to the receptor well wasassumed to be fixed at 152 m (500 feet).Consequently, fixed values of thelongitudinal and transversedispersivities were used in the model.The values of vertical dispersivity wereassumed to vary uniformly.

Several commenters criticized theassumption that dispersivity values didnot vary and reflected only the fixeddistance selected in the model. Theyalso suggested that the ratio oflongitudinal to transverse dispersivityused in the model was too low. Thebasis of their comments is that fieldvalues of dispersivities have beenshown to depend on, and usuallyincrease with, the travel distance.

The Agency agrees with thecommenters and now calculates thethree components of dispersivity basedon a detailed analysis of data gatheredfrom field tests (the model backgrounddocument [Ref. 91 presents a detaileddiscussion on dispersivity values and

provides references to the field data).The Agency believes that the revisedapproach, reflecting the distance-dependent nature of the dispersivityvalues and different relationshipsbetween the dimensional dispersivities,is more realistic and consistent with theavailable data.

EPACML also requires thespecification of a dispersivity parameterfor transport in the unsaturated zone.Since the transport equation in theunsaturated zone is one-dimensional,only the longitudinal (vertical)dispersivity value is required and iscalculated as a function of the distance(i.e., the depth to water table) traveledin the unsaturated zone.

vi. Hydraulic Conductivity. InEPASMOD, the value of hydraulicconductivity in the saturated zone wasestimated using the Kozeny-Carmen(Ref. 9) expression, which relateshydraulic conductivity to porosity, themean particle diameter of the aquifermaterial, and the fluid properties(density and viscosity). This relationshipwas based on an assumed ground watertemperature of 15 degrees C and did notreflect changes in the fluid propertieswith temperature.

Commenters expressed concern withthis assumption because ground watertemperature is known to typically rangein temperature from 4 degrees C to 30degrees C. A few commenters alsoexpressed concern regarding the validityof using this empirical relationship.

In response to these comments, theAgency generalized the expression toinclude the effects of changes intemperature on fluid viscosity and fluiddensity. That is, the fluid viscosity anddensity are now considered as functionsof temperature rather than as constants.The Agency realizes that the hydraulicconductivity also depends on physicalproperties, such as grain shape, grainsize distribution, packing, and tortuosityof the porous media. Porositymeasurements reflect the compositeresult of these textural characteristicson the structural arrangement of theporous media. The range of porosityvalues derived in EPACML indirectlyreflect the impact of these properties.Therefore, in view of the Agency'sobjective to represent the widevariations expected from site to site, theAgency decided to retain the Kozeny-Carmen equation, except for themodification described above.

vii. Hydrolysis. As already discussedin section fI.E.2., the EPACML modelaccounts for reduction in constituentconcentrations due to hydrolysis. Thisresults in higher DAFs for constituentsthat hydrolyze during transport than for



constituents that do not. The DAFpredicted by the model for some of theseconstituents ranges up to one million.Thus, in some cases, wastes would notbe considered hazardous unless theycontain large amounts of thesetoxicants; still, in other cases, noamount of toxicant in the waste woulddefine it as hazardous under thisscenario. Therefore, the Agency did notbelieve it appropriate to include theseconstituents in the TC (see Table E-2 forlist of constituents that appreciablyhydrolyze). Furthermore, the model doesnot account for the degradation productsthat are produced as the originalconstituents hydrolyze. That is, whilethe decrease in the concentration of theoriginal constituent is accounted for, theresultant increase in concentration ofthe hydrolysis products is not. Severalcommenters stated that the toxicity andtransport of the potential hydrolysisproducts should be considered to fullyassess the hazards posed by theconstituents that hydrolyze.

The Agency agrees with thecommenters and is (1) determiningwhich byproducts result from hydrolysisand (2) developing an appropriateprotocol for predicting the concentrationof hydrolysis byproducts (see Table E-2). Once this protocol is developed, theAgency will determine whether any ofthese toxicants should be added to thelist of constituents. While the Agencyconsidered including these constituentsat a higher dilution and attenuationfactor until this work was completed,the Agency does not have sufficientinformation at this time to determinewhich of the constituents listed in TableE-2 will eventually be added to the TCand at what level.

TABLE E-2-HYDROLYZING CONSTITU-ENTS LISTED IN THE JUNE 13, 1986PROPOSED RULE

AcrylonitrileBis(2-chloroethyl) etherMethytene chloride1,1,1 ,.2-Tetrachloroethane1,1,2,2-Tetrachloroethane1,1.1-Tdchtloroethane1,1,2-Trichloroethane

viii. Steady-State Assumption. Asimplemented for today's rule, EPACMLwas solved for the steady-statecondition. Thus, the solution representsthe case where leaching has occurredfor a period of time that is sufficientlylong to allow the concentration at thereceptor well to become constant.Several commenters noted that, incertain circumstances, use of the steady-state solution would lead tounreasonably low DAFs. In particular, in

situations where the mass of aconstituent is relatively low in thesource facility (i.e., the landfill has avery limited quantity of the constituentavailable to contaminate leachate), thesteady-state model will continue toassume the existence of a very largequantity of the constituent and, hence,over-predict the resulting concentrationat the downgradient ivell. Under suchcircumstances, the commenters argue,the Agency should accommodate thisphenomenon by using a transientsolution in deriving appropriate DAFs.

The Agency agrees with thecommenters and has initiated a study tothoroughly investigate the problemdescribed above. Based uponpreliminary investigations alreadycomplete, however, the Agencycontinues to believe that application ofthe steady-state model to manyconstituents is appropriate and ispromulgating regulatory levels for thoseconstituents based upon the results ofthe steady-state model. The preliminaryinvestigations have also led to adecision to postpone the promulgation ofregulatory levels for constituents thatare believed to be more appropriatelyevaluated with a transient solution. TheAgency is continuing to refine theapproach required to implement thetransient solution but results to datesuggest that this latter group ofconstituents require unreasonably largequantities in the source facility to insurethat the steady-state solution isappropriate. For example, under someconditions even when the constituentsexist at concentrations in excess of 1000ppm of the solid waste within the entirevolume of the landfill, the steady-statecondition is not realized. Therefore,based upon the preliminary analysis,regulation of these constituents basedupon the DAFs predicted by the steady-state model may not be appropriate.

Preliminary investigation of thiscondition was completed for all of theoriginally proposed constituents. Allconstituents were assumed to exist inthe "tested" waste at 1000 ppm.Furthermore, the "tested" waste wasassumed to occupy 100% of the availablefacility capacity (i.e., the "tested" wasteis the only solid waste in the facility).As a reasonable worst case scenario,the DAF was derived by the transientmodel for each constituent under theseconditions. Because the aboveassumptions are very conservative, mostof the DAFs derived for the constituentswere found to coincide with the steady-state values. That is, sufficient masswas available to insure that steady-stateconditions were reached. Accordingly,regulatory levels for these constituents

are being promulgated in this rule. Forthe following constituents, however, thesteady-state condition was not achievedunder this scenario:

phenol1,2-dichlorobenzenecarbon disulfideisobutanol2,3,4,6-tetrachlorophenoltoluene

Accordingly, the Agency is postponingthe promulgation of regulatory levels forthese six constituents until such time asthe investigations are complete. Oncethese investigations are completed, theAgency will take the appropriate action.

ix. Biodegradation. The subsurfacefate and transport model does notaccount for biodegradation processes inthe subsurface environment. EPArecognizes, however, thatbiodegradation is an important process

- that can reduce concentrations undereither aerobic or anaerobic conditions.-Accordingly, the EPA has constructedthe model so that it can theoretically bemodified to include these processes forexperimentally derived biodegradationrates. Biodegradation processes havenot been included because the data.bases to support this portion of themodel are currently insufficient.

The first major data deficiency is thatthe model incorporates many diversesubsurface environmental conditionswhere as constituent-specificbiodegradation rate data typically existfor only a few (if any] subsurfaceenvironments. EPA also recognizes thatalthough the kinetic equationsdescribing the degradation of hazardousorganic chemicals in manyenvironments are available, theseequations have not been sufficientlyevaluated in the subsurface environment(Ref. 10, 11, 12). Second, the Agencyconsiders data on the formation oftransformation products to beinsufficient. Third, the key processesthat can affect the subsurfacebiodegradation rate are not wellunderstood. These processes includesorption, pH, temperature, nutrientavailability, toxicity, and others. Forexample, while nutrient levels in theenvironment are generally consideredsufficient for low populations ofmicroorganisms, the microorganicpopulation at which the nutrientavailability in the environment becomesa limiting factor is not known.Additionally, while sorption is wellunderstood for hydrophobic compoundsat low concentrations (Ref. 13). atconcentrations where the compoundscan form small droplets or becomeentrained in the micropores of the

11823 .This information is reproduced with permission from HeinOnline, under contract to EPA. By including this material, EPA does not endorse HeinOnline.


subsurface matrix, sorption effects arenot well understood. The effects oftemperature have been characterized ininnumerable studies of isolatedmicroorganisms, but the kinetics ofthese effects have only recently beeninvestigated in environmental samples(Ref. 14). Finally, the toxicity ofhazardous chemicals to themicroorganisms themselves is only nowbeing investigated (Ref. 15).

Accordingly, the Agency is continuingto gather data to refine the modeling ofbiodegradation,, but has not been able toinclude biodegradation in the groundwater transport model at this time. Inthis regard, EPA has publishedguidelines for developing anaerobicmicrobiological biodegradation ratedata for chemicals in the subsurfaceenvironment (see 40 CFR 795.54). Resultsdeveloped under these guidelines willprovide data on kinetic rates ofdegradation, and to a lesser extent, onthe effects of pH and temperature onthese rates. Similar guidelines have notbeen developed for aerobic systems atthis time. Data developed under 40 CFR795.54 may be considered for use in themodel at some future time.

x. Summary of General Modifications.The Technical Background Document(Ref. 9] describes in detail the modelrevisions, including options developedbut not implemented for the purposes ofestablishing the regulatory levels fortoday's rule. A summary of the majormodel options and proceduresimplemented for the rule follows:* The model was run for the steady-state case. The initial condition was aconstant concentration. The equationswere solved for infinite time.

* The unsaturated zone module wasincluded in the analysis.

* Concentrations can be predicted atwells placed at any position. The wellscan be allowed to draw from anyselected depth.

* The updated method of computingdispersivities as a function of randomlongitudinal well locations was used(designated in the model as the "Gelharprocedure").

* The option implemented for settingthe boundary conditions between theunsaturated zone and the aquifer wasthe one that limits the lateral extent ofthe plume to the downgradient facilitywidth, computes vertical mixing anddispersion underneath the facility, andestimates the maximum sourceconcentration within the plume basedon mass balance requirements. Anycombination of conditions that violatedthese requirements and, thus is notphysically realistic, was rejected.

The above options and additionaloptions are listed in the background

document for the model (Ref. 9).Specifically, the model input and controlvariables, as required and accepted bythe computer code, are listed for eachcomputer run used to set regulatorylevels in today's rule.

By incorporating these modifications,the EPACML, as applied to landfills,models the following basic features:

* The landfills are filled to capacityand covered with native soil.

* Caps are characterized as being in afailed or deteriorated state. Thus,permeabilities are set to be higher thanwould be typical of landfills with anundamaged cap. It is assumed that linersare not present.

• All wells (exposure points) areconsidered to be downgradient in everymodel run. The longitudinal distanceparallel to the direction of ground waterflow is determined from data describedlater in section III.E.3.

* Lateral well location is determinedby allowing the position to uniformlyvary at random within the plume widthand with the additional constraint thatthe location also must be within an areadefined by lines at 90-degree anglesfrom the direction of ground water flowat the midpoint of the downgradientboundary of the facility.

• Vertical well location is determinedby allowing the position of the wellintake point to uniformly vary atrandom over the entire aquifer depth.

* The landfill storage capacity isassumed to be sufficient toaccommodate sufficient mass of eachconstituent to allow a steady-statecondition to exist. This produces aninfinite source initial condition.

* Conitituents contained within thelandfill do not degrade.

• Infiltration rates are represented asannually averaged flows based on 20-year climatic records and concomitantwater balance calculations.

b. Use of the EPA CML for SurfaceImpoundments. Because some wastesare managed in surface impoundmentsrather than landfills, severalcommenters indicated the need toanalyze and include the results obtainedby considering a surface impoundmentmismanagement scenario. They arguedthat dilution/attenuation factors (DAFs]generated by modeling a landfillscenario would be too stringent forwastes managed in surfaceimpoundments. Based upon thesecomments, the Agency decided toinvestigate whether surfaceimpoundment DAFs would besignificantly different from landfillDAFs. EPA requested comment on theuse of this data in the August 1, 1988notice.

Based upon this investigation, theAgency has concluded that the use ofDAFs based on a landfill scenario isappropriate in establishing theregulatory levels for wastes managed insurface impoundments. EPA used theEPACML model to confirm this analysisby modeling a surface impoundmentmismanagement scenario.

This conclusion is based on theAgency's evaluation of the physicalparameters that would lead to differentDAFs for surface impoundments thanfor landfills. A key factor that could leadto differences in the DAFs from thesetwo types of management units (surfaceimpoundments and landfills) is thedifference in total leachate infiltrationrates. The infiltration rate is equal to theproduct of the leachate mass flux (massper unit area per unit time) and the areaof the management unit. For surfaceimpoundments, the mass flux can beconsiderably greater than for landfills.However, to the extent that the area ofsurface impoundments is typicallysmaller than the area of landfills(although some atypical surfaceimpoundments can be as large, if notlarger than landfills), the effects of thegreater leachate flux are somewhatoffset. That is, while the flux is greater,the area is smaller, resulting inrelatively similar leachate infiltrationrates.

A second factor that affects the DAFsis the situation in which the leachateflux is large and the ground watervelocity is relatively small. In thesesituations, a ground water mound mayform below the management unit. Thiseffect is more typically associated withsurface impoundments because of theirhigher leachate fluxes; this effect shouldresult in smaller DAFs (and, thus, morestringent regulatory levels] than wouldbe predicted if the mounding did notoccur. As a result of these factors, theAgency concluded that DAFs from asurface impoundment scenario would beequivalent to or less than DAFs from alandfill scenario.

To confirm this conclusion, EPA usedEPACML to evaluate a surfaceimpoundment scenario. The mainfeatures of the surface impoundmentscenario, as simulated using EPACML,are as follows:

* The surface impoundments arefilled to their fluid capacity and areassumed to operate on a continuousbasis.

* Bottom layers are characterized asbeing in a more permeable state(typically ten times greater) than thosefound in field studies.

e Location rules for downgradientwell positions and lateral and vertica'



locations are identical to landfills. Thedata base for longitudinal distances isdifferent, however..

* The operating life of the surfaceimpoundment is assumed to besufficient to accommodate a sufficientmass of constituent to allow a steady-state condition to exist. This assumptionproduces an infinite source initialcondition.

* The leaching rate from a surfaceimpoundment depends on, among otherfactors, the ponding depth in theimpoundment and the characteristics ofthe bottom materials. The HydrologicEvaluation of Landfill Performance(HELP) model used in evaluating thelandfill data is inadequate to determinethe leaching rates from surfaceimpoundments. Therefore, the leachingrates from subtitle D surfaceimpoundments were estimated byconsidering the relationship between thevelocity in the vertical direction and thesubstrate's porosity and permeabilityand the solution of the nonlinear steadystate flow problem. To be conservative,the Agency used a permeability valueten times higher than the value typicallyreported in field studies as an input forcalculating leaching rates (the source ofthese data are discussed below).

* The Agency has not yet conducted adetailed survey for subtitle D surfaceimpoundments, but the Agencyconducted a review and analysis of dataon subtitle D units in RCRA FacilityAssessment (RFA) Reports (Ref 16). Aset of data on subtitle D surface'impoundments was obtained from thisanalysis and used as inputs to theEPACML. Additional data werecompiled from aerial photographs byEPA's Environmental PhotographicInterpretation Center (EPIC).

* The data extracted from RFSsincluded the area of the surfaceimpoundments and the distance todowngradient drinking water wells asdetermined by EPIC.

e The ponding depth data for thesubtitle D surface impoundments werereported by E. C. Jordan (Ref. 9). Thehydraulic conductivity of the bottommaterials was chosen as 1.0 E-6 cm/sec.This value reflects the effect of gradualsettlement and compaction of sedimentsat the bottom, because surfaceimpoundments tend to fill up withsediments over a period of about 20years or so. The Agency believes thatthe hydraulic conductivity value of 1.0E-6 cm/sec represents a reasonableworst-case value. These values wereused in conjunction with EPACML toestimate DAFs for the surfaceimpoundment data.

As expected, DAFs predicted forqurface impoundments are somewhat

smaller than the corresponding valuesfor landfills (see section III.E.4).However, because the EPACML doesnot incorporate the mounding effect, thesurface impoundment evaluation wasrestricted to include only those caseswhere mounding would be minimal and,thus, reasonably ignored. As aconsequence of limiting the evaluationto these cases, the modeling results tendto omit some worst case scenarios. Thatis, if all possible cases were included,rather than just the "no mounding"cases, the DAFs for surfaceimpoundments could be somewhatlower and, thus, the downgradientconcentrations may be higher than thoseestimated by the EPACML model. TheAgency thus believes that the omittedsurface impoundment conditions shouldbe further investigated and may result inmore stringent regulatory levels. TheAgency believes, however, that theDAFs produced by the EPACMLanalysis properly delineate wastes thatare clearly hazardous wastes.

3. Newly Acquired DataAs previously described, the DAFs

proposed on June 13, 1986, werecalculated based on the subtitle Dlandfill scenario. However, subtitle Dlandfill data were not available to theAgency at that time, and instead,subtitle C landfill data were used.

Several commenters criticized the useof subtitle C (hazardous waste) landfilldata. The Agency agreed with thecommenters and has based the final ruleon data from a survey of solid wastesubtitle D landfills.

a. Landfill Data. The Agencyconducted a survey of municipal solidwaste landfills in the U.S. (Ref. 6). Thesurvey used a stratified design based onfacility size. The results were tabulatedbased on 1,102 completedquestionnaires. The survey yielded dataon area of landfills, distance to thenearest downgradient drinking waterwells, and thickness of the unsaturatedzone. These data are site-specific,corresponding to individual solid wastelandfills located throughout the UnitedStates. The survey data were analyzedto develop distributions of these site-specific parameters and used as inputsto EPACML, as described in the modelbackground document (Ref. 9). The inputfrequency distributions are alsopresented in the background document.

EPA also collected additional data onleachate generation at municipallandfills. EPASMOD requires, as input,the leachate distribution from thebottom of the landfill. The leaching ratedistributions for the June 13, 1986,proposal were based on the use of asingle soil type, loam, as the cover soil

for the landfill. These distributions wereestimated using climatologic data for atotal of 30 cities nationwide,representing the median range for eachof 18 climatological conditions or zonesidentified in the 48 contiguous states.

The assumptions of a single soil typeand 18 climatic zones were criticized asnot being realistic and resulting in anoverly optimistic cap performance. Thecommenters suggested enhancing thedata base by including simulation ofdifferent soil covers.

In response to these comments, theAgency has implemented a number ofchanges. The Agency believes that thesemodifications significantly improve thevalidity of the leachate flux distributionand make it more realistic.

Soil Type

The Soil Conservation Service (SCS)has a county-by-county soil mappingprogram underway. More than 90percent of the land area in the U.S. hasbeen mapped, and soil data representingapproximately 51 percent of the totalland area in the U.S. have been enteredinto a computer data base. Using thisdata base, the soil classifications weregrouped according to the U.S.Department of Agriculture's definitionsof coarse, medium, and fine textures.These three categories are representedin EPACML by soils equivalent inproperties to sandy loam, silt loam, andsilty clay loam for the landfill covermaterials. The latest results show thatcoarse grained soils, medium grainedsoils, and fine grained soils represent15.4, 56.6, and 28.0 percent, respectively,of the soils that have been mapped thusfar.

Climatic Zones

The number of cities representingclimatic variations that were used todevelop frequency distributions for theleachate generation has been increasedfrom 30 to 100. The reason for thischange was to reduce the chance thatany one city would provide anunrepresentative percolation rate in itsclimatic range.

The climatic data base used inEPACML was enhanced to include sixprecipitation ranges and five ranges ofpan evaporation rates, thereby resultingin 30 climatic ranges as opposed to the18 described in the earlier proposal. Forthe climatic ranges so defined, thepercentage of the area of the 48 statesrepresented by each range wascalculated, and the percent arealaverage was used to weight thepercolation (recharge and/orinfiltration) rate estimated for theselected cities in each range according


11826 Federal Register /. Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

to probable relative occurrence in the.U.S. The effect of these changes is toprovide more representative values ofthe overall national distribution of theleachate flux.

After the percolation data for thelandfill were calculated using the HELPmodel (Ref. 9), the climatic ranges werefurther subdivided to account for widevariations in percolation within a range.This resulted in separate subrangesbeing established for some Californiacities (Los Angeles, Sacramento, SanDiego, and Santa Maria), and twoOregon cities (Medford and Astoria).

Percolation rates for each of theselected cities in the 48 contiguousstates were determined using silt loam,sandy loam, and silty clay loam coversoils. These soils, based on dataobtained from the SCS, appear torepresent the most common soil types inthe U.S., and thus the most common soilto be used as covers for landfills. Theyalso span the range of likely cover soils,from fine-grained to coarse-grained, orfrom low to high percolation rates.Simulations were performed for each ofthese soil types, and the resultsweighted according to the frequency ofoccurrence for each type.

The leaching rate flux was determinedby using the average, weightedpercolation rate from the cities in eachclimatic range. The model backgrounddocument (Ref. 9) presents the data usedand the accompanying changes to theJune 13, 1986 proposal runs.

b Chemical-Specific Parameters. Inthe EPASMOD proposal, chemicalparameters, such as hydrolysis rates,were used to calculate the relativeretaidation factors and degradationrates for selected compounds. Some ofthe chemical-specific parameters used inthat model were estimated based on abrief review of the existing chemicaldata. Some commenters criticized someof the parameter values selected andused for that proposal as beingnonrepresentative of the range ofparameter values.

The Agency has an ongoing programfor the measurement of constituent-specific parameters and for the reviewof new constituent-specific data asreported in the current scientificliterature. Some hydrolysis rateconstants and octanol-water partitioncoefficients used in the proposal havebeen revised to reflect the most recentlaboratory measurements and recentvalues reported in the literature. Theupdated parameter values are given inthe background document (Ref. 9) andrepresent either measured or bestavailable values.

4. DAF Evaluation

a. Selection of an AppropriatePercentile. As described earlier, theEPACML was used to investigate theexpected range of DAFs associated withmismanagement of solid wastes. Asgenerated by EPACML, the DAFrepresents the expected reduction in theconcentration of a constituent duringtransport through soil and ground waterfrom the leachate release point (bottomof the waste management unit) to anexposure point (a well serving as adrinking-water supply). The wide rangeof possible environmental settings (e.g.,ground water velocities, pH,temperatures, etc.) and the multitude ofpossible scenario configurations (e.g.,facility area, distance to downgradientwells, etc.) result in an extremely widerange of DAFs. Monte carlo simulationwas used to implement EPACML, andthe resulting cumulative frequencydistribution can be viewed as a rankedorder of increasingly higherdowngradient concentrations expectedfrom the "best-case" situations (largeDAFs) to the "worst-case" situations(small DAFs) for the scenario beinginvestigated.

The Agency's proposed approach wasto define DAFs representative ofreasonable worst-case conditions asthose corresponding to the 85thpercentile of the cumulative frequencydistribution. The Agency receivednumerous comments on the selection ofthe 85th percentile, which are addressedin Section d, following.

b. Resulting DAFs for Landfills. TheDAF values corresponding to variouscumulative frequency levels for landfillsare as follows:

Percentile 80 85 90 95

All nondegrading constitu-ents ....................................... 328 134 47 12

Chloroform' .............................. 385 152 52 14

'The DAFs for chloroform are slightly higher thanfor the other nondegrading constituents becausechloroform is expected to hydrolyze slightly duringtransport.

The similar DAF values fornondegrading constituents andchloroform arises because all theseconstituents either do not degrade at allor only degrade slightly.c. Resulting DAFs for Surface

Impoundments. The DAF valuescorresponding to various cumulativefrequency levels for the surfaceimpoundment investigations describedin E.2.b of this section are as follows:

Percentile 80 85 90 95

All nondegradng constitu-ents...; ..................... 226 111 51 19

Chloroform .............................. 227 111 52 19

As with the landfills, the constantDAF for all constituents reflects the factthat nondegraders and very slowdegraders have virtually identicalenvironmental fate for the scenarioinvestigated. As the resulting numbersindicate, within a reasonable degree ofaccuracy, the DAFs for waste managedin surface impoundments are equivalentto the corresponding landfill DAFs.

d. Final DAF Selection. The Agency'spurpose in developing dilution/attenuation factors (DAFs) is to identifywastes whose leaching behaviorindicates that they may pose a hazard tohuman health unless they are controlledunder subtitle C management standards.Thus, the Agency developed asubsurface fate and transport model thatsimulates a subtitle D management unit(i.e., a municipal landfill) and thesubsurface environment that would beencountered by toxic constituents asthey migrate from the management unitto a drinking-water well. In order tomake the model's output (DAFs) asrealistic as possible, the Agencyimplemented the model using real-worlddistributions for parameter values (e.g.,areas of landfills, properties of thesubsurface environment, etc.) wheneverpossible. The monte carlo structure ofthe simulation allowed the modelingresults to be presented as a cumulativefrequency distribution or probability.That is, the model expresses theprobability that a toxic constituentdisposed of in a municipal solid wastelandfill will undergo certain dilution/attenuation as it moves through asubsurface environment to an exposurepoint. Thus, there is a different DAF foreach selected probability.

In its June 13, 1986 proposal notice, theAgency proposed the use of the DAFcorresponding to the 85th percentilecumulative frequency level andrequested comment on the use of otherpercentile levels. Comments werereceived urging the use of both higherand lower levels. Recommendations forusing the 80th percentile cumulativefrequency were justified by assertionsthat the assumptions used in the modelwere already unduly conservative. Onecommenter noted that EPA could stillrely on the listing program to regulatewastes whose leachate concentrationswould not exceed the regulatory levelsderived from the lower percentile DAFbut that are still considered hazardous.



Other commenters argued that the 85thpercentile was not adequately protectiveof human health and the environment.One commenter, claiming thatassumptions in the model were notconservative enough, recommended thatthe 95th percentile be used.

In selecting the appropriate level, theAgency recognizes that there is noconsensus "correct" level forinterpreting modeling results. This hasresulted in a particular challenge indeveloping today's rule, wherein aquantitative approach is being used forguidance in answering what is a partlyqualitative question-namely, "what isthe human health impact of unregulatedmanagement of certain types of wastesin a 'reasonable worst-case' disposalscenario?" While the Agency believesthat the 85th percentile is an appropriatechoice to represent a reasonable worst-case result, consideration of therelationship of the 85th percentile DAFto other percentile DAFs is alsoappropriate. That is, the Agencybelieves that the behavior, or shape, ofthe upper portion of the cumulativefrequency distribution curve should alsobe evaluated in order to determine howcritical the selection of a particularfrequency level is to the DAF.

Another consideration in determiningthe appropriate DAF value, independentof the selected cumulative frequencylevel, is the accuracy inherent in thedata set used. Given that there is someuncertainty associated with any data setused to represent possible values forany parameter, and that the modelrequires values for many parameters,the Agency believes that the selectedDAF value should not imply an unduedegree of accuracy.

After considering the above factors,the Agency has concluded that a DAFvalue of 100 is appropriate forestablishing the regulatory levels for theconstituents included in today's rule. 1

First, the Agency believes that,considering the number of parametersfor which distributions of values wereestablished (in order to represent a"generalized" scenario), a DAF with anorder-of-magnitude precision is

As explained previously, the Agency is not intoday's rule, promulgating regulatory levels forseveral of the constituents for which regulatorylevels were proposed. These constituents includethose that are expected to hydrolyze appreciablyand those for which it has not yet been determinedwhether the steady-state solution to the subsurfacefate and transport model is appropriate. Once theissues associated with these constituents areresolved, the Agency will promulgate or repropose(as warranted) regulatory levels for theseconstituents. For cases where regulatory levels arereproposed, they may incorporate dilution/attenuation factors other than 100.

appropriate.2 Second, in selecting thisDAF value of 100, the Agency noted thatthe 80th and 90th percentile DAFs, aswell as the 85th percentile DAFs,indicate that constituents migrating inthe modeled disposal scenario will bediluted by approximately two orders ofmagnitude. This is also true of thepredicted DAFs from the data used forsurface impoundments. Thus, EPAbelieves that a DAF data used forindicating dilution by two orders ofmagnitude (i.e. 100) is appropriate.Moreover, as the data indicate, on anorder-of-magnitude scale, the predictedDAF is not extremely sensitive to theexact cumulative frequency value thatwas selected.

The Agency points out that theconsiderations leading to the use of 100to represent the model-predicteddilution/attenuation factors are uniqueto today's promulgation. In other cases,different conclusions may be moreappropriate. For example, whenparameter values can be more narrowlydefined (as in site-specific evaluations),the higher degree of precision may beappropriately ascribed to the model-predicted DAFs. Likewise, where theprogram goals are different (i.e. otherthan to identify levels that are indicativeof wastes that clearly are hazardous),the selection of a value that represents acumulative frequency value other thanthe 85th percentile may be warranted.

F. Toxicity Characteristic LeachingProcedure (TCLP) (Method 1311)

1. Introduction

The development of the TCLP and therole of the test in identifying a waste ashazardous were discussed at length inthe June 1986 proposal (51 FR 21648).Today, EPA is promulgating the TCLP,with some improvements andmodifications, as a replacement to theEP for use in the identification ofhazardous waste. (The revised TCLP ispromulgated in Appendix II to 40 CFRpart 261 and has been designated asEPA Method 1311 and will beincorporated in "Test Methods forEvaluating Solid Waste Physical/Chemical Methods-SW-846".)

The Agency received numerouscomments in response to the FederalRegister notices (51 FR 1602, 51 FR21648, 51 FR 24856, 51 FR 33297, 51 FR40593, 51 FR 40643 and 53 FR 18792)related to the TCLP procedure. Inparticular, EPA received close to 140comments on the application of theTCLP in response to the June 1986

2 The health data is only valid to one order of

magnitude precision and thus may control the totalnumber of significant figures.

proposal. The comments coveredgeneral issues such as the relationshipto the EP, the adequacy of researchsupporting TCLP development andspecifically, the statistical treatment ofdata. Commenters also addressedtechnical issues including the suitabilityof the zero head space extraction (ZHE)vessel; the types of filters, reagents, andleaching media; the quality assurancerequirements; and the multipleextraction and oily waste extractionprocedures. In addition, comments werereceived on the use of quantitationlimits for establishing regulatory levels.All the comments were categorized andsummarized by issue and are presentedin the technical background documentalong with the Agency's response tothese comments (Ref. 4).

In this preamble, only certaincomments are discussed, which include(a) the applicability of the TCLP tospecific types of waste (i.e., solidifiedwastes); (b) the analytical difficultiesencountered during the analysis of theTCLP extract for phenolic compoundsand phenoxy acid herbicides; and (c) theuse of quantitation limits. The first twocomment issues are presented belowwhile the last comment and theAgency's response is given in sectionIV.C. of this preamble.

2. Adoption in the LDR Rulemaking andModification from the Proposed Rule

The TCLP was promulgated inAppendix I to 40 CFR part 268 onNovember 7, 1986 (51 FR 40593), as partof the Land Disposal Restrictions Rulefor Solvents and Dioxins. The TCLP isused in the Land Disposal Restrictions(LDR) program to determine whethercertain wastes require treatment prior toland disposal and to determine whethercertain treated wastes meet theapplicable treatment standards. Intoday's rule, the Agency hasincorporated two other clarifications tothe TCLP as proposed on May 24, 1988(53 FR 18792) for use in both the LDRand the TC programs.

The Agency modified the proposedTCLP as a result of the Agency's ownresearch and comments received on theJanuary 14,1986 (51 FR 1602) proposalfor the LDR program and the June 13,1986 (51 FR 21648) proposal for the TC.These modifications to the TCLP werepromulgated on November 7, 1986 forthe LDR program. On May 24, 1988, theAgency proposed additionalmodifications to the TCLP for both theLDR and the TC. In today's rule, theAgency has adopted two of theseproposed changes, and is promulgatingthe revised TCLP for use in both theLDR and TC programs.



The first change is the insertion of amore detailed method flow chart toexplain how analysts are to perform thetest. Comments expressed confusionregarding the original flow chart (e.g.,that it was difficult to follow), so theAgency has added this new chart toeliminate confusion. The second changeis the addition of new equipmentsuppliers to provide more informationon the availability of suitable testingequipment. The new equipmentsuppliers include two manufacturers ofrotary agitation devices, EnvironmentalMachine and Design, Inc., of Lynchburg,VA, and Millipore Corporation ofBedford, MA; two manufacturers of azero-headspace extractor (ZHE) vessel,Lars Lande of Whitmore Lake, MI andEnvironmental Machine and Design,Inc., of Lynchburg, VA; and threemanufacturers of filter media, MilliporeCorporation of Bedford, MA; NucleoporeCorporation of Pleasanton, CA; and.Micro Filtration Systems of Dublin, CA.These manufacturers are listed inTables 2, 3, and 5, respectively, of themethod (i.e., Appendix II of 40 CFR 261),along with company telephone numbersand equipment model numbers.

Another more substantial proposedmodification, the addition of a stainlesssteel cage insert to the bottle extractor,will not be added by the Agency at thistime for the reasons discussed below.The Agency had proposed thismodification to eliminate therequirement for particle size reductionfor certain types of wastes (e.g.,solidified materials).

3. Applicability of TCLP to SolidifiedWastes

Some commenters expressedreservations regarding the applicabilityof the TCLP to specific types of wastes.The wastes of concern were solidifiedwastes. Numerous commenterssupported the reinstatement of thestructural integrity procedure (SIP) orsome other stability criterion forsolidified wastes. They argued thatparticle size reduction (i.e., "grinding")would be inappropriate in thoseinstances where solidification of thewaste is needed to meet the bestdemonstrated available technology(BDAT) provisions of the law and thatgrinding may not adequately representthe weathering process or the effect ofvehicular traffic. Commentersrecommended that the Agency retain theSIP. Others agreed that particle sizereduction is inappropriate for stabilizedmonolithic wastes and producesunrepresentative results. Specifically,commenters stated that particle sizereduction alters the physical characterof many solidified wastes by destroying

the cementitious property of thesewastes in such a way that the leachingrate increases unrealistically. Byincreasing the surface area that isavailable to attack by a leachingmedium, the amount and rate at whichsubstances may be leached increases.Inasmuch as waste grinding is notnormally employed in municipallandfills, particle size reduction rendersthe TCLP a less accurate model ofleaching in a municipal landfillenvironment.

Since the June 13, 1986, proposal, theAgency has reviewed the use of the SIP,which uses a drop-hammer to test theintegrity of the waste and to reduce itssize if it fractures. The Agency foundthat although the SIP may simulate thepotential of a monolithic waste to bedegraded by vehicular traffic on alandfill, it cannot address certain otherstresses acting on the waste (e.g., wet-dry and freeze-thaw cycles). In addition,the SIP can only be used for wastes thatcan be prepared in a sample of specifieddimensions.

While evaluating the use of the SIP,the Agency found that dense, hardmaterials would occasionally break theglass extractor bottle. To preventbreakage of the bottles, the Agencydeveloped a cage insert for the extractorbottle. The cage, which is designed toprevent contact between the hardsample and the sides of the bottle, isconstructed of 0.25-inch stainless steelwoven mesh. Experiments have shownthat the use of the cage prevents bottlebreakage.

While evaluating the utility of thecage, the Agency noticed that wastesthat were believed to be well-solidifiedretained their monolithic nature in thecage during extraction, whereas wastesthat were believed to be less well-stabilized (even though some of themhad passed the SIP) were broken intosmall pieces during the extraction. Thus,these experiments led to the proposeduse of the stainless steel wire cage in theextraction apparatus (53 FR 28792 May24, 1988). The use of this device, theAgency believed, tested the physicalintegrity of the sample and reducesparticle size appropriately.

Commenters expressed support forthe cage modification-that it is a stepin the appropriate direction toward amore realistic assessment of theenvironmental leaching potential of asolidified waste. However, commentersalso had concerns that the cage wasproposed prematurely-that not enoughevaluation of waste samples using thecage had been done. Specifically,commenters argued that the cage couldpossibly leach significant quantities of

nickel and chromium to contaminatemetals analysis; that it would bedifficult to collect representativesamples in some cases; that there wereproblems with the configuration of thecage so that it could not beaccommodated to fit a large array ofbottles; that the cage's constructionprovided numerous crevices and asignificant amount of surface area forwaste residue to collect, makingeffective cage cleaning difficult; and thatsolidified samples could be molded intoa shape that would cause less materialto be sloughed off during extraction,leading to a less aggressive test. TheAgency agrees with these commentersand has decided not to go forward withthe cage modification at this time. TheAgency currently has work underway toevaluate all these concerns, and willcontinue to evaluate modifications ofthe TCLP and will propose furtherimprovements as they are developed.

4. Analytical Methods

Several comments addressed theanalytical difficulties of analyzing theTCLP extract for phenolic compoundsand phenoxy acid herbicides by gaschromatography/mass spectroscopy,SW-846 Method 8250 (GC/MS). Theseanalytical difficulties include theinterference of the acetate ion in theTCLP leach fluid with the columnpacking material of Method 8250.Removal of the acetate ion is oftendifficult, and equipment damage mayresult if the acetate is not removed (i.e.,the acetate Ion can destroy the columnpacking material).

The Agency agrees that analysis foracidic compounds by GC methods maybe difficult, but not impossible. TheAgency suggests the use of a bonded-phase capillary column (Method 8270) toreduce the interference from acetate. Inaddition, the Agency is investigatingother methods for removal of the acetateion from the extract before analysis forthe phenolics and herbicide andwelcomes alternative suggestions,especially when accompanied bysupporting data.

The Agency had suggested the use ofHPLC as an alternative to GC/MSanalysis of phenolics and phenoxy acidherbicides. However, severalcommenters believed that an HPLCmethod is generally regarded as moreexpensive and not as readily availableas GC/MS. In addition, somecommenters indicated that GC/MZ Is abetter method analytically than HPLC,and that HPLC would be more difficultto implement. The commentersexpressed that, at the very least, alengthy verification process would be



required to determine an HPLC method'sruggedness and reproducibility and todetermine the most effective cleanupsteps. The commenters further suggestedthat even if an effective HPLC cleanupprocedure is developed and approved bythe Agency, it is bound to increase theanalytical costs and slow down theanalytical throughput. Even withoutconsidering this restriction, theprocedure of leaching the organics intoan aqueous medium, followed byextraction, recovery, and concentration,is bound to require more manpower andthus more money than a more directsolvent extraction of the solid itself. Thecommenters indicated that methods foranalyzing solid waste for semi-volatileorganics and phenoxyacid herbicidesare already described in SW--846 andshould be the preferred methods, bothfor practicality and as a way ofproviding a reliable test.

The Agency agrers that theGC/MS orGC/electron capture (GC/EC) analysisis more advantageous for the analysis ofphenolics and phenoxy acid herbicidesbecause the equipment is more readilyand widely available than HPLC,despite the associated difficulties. HPLCmethods for phenolic compounds are notincluded in the third edition of SW-846because of a lack of validation data. TheAgency will allow only the use of theGC/MS method until such time that theAgency proposes an HPLC method.G. Testing and RecordkeepingRequirements

1. Existing Requirements for GeneratorsUnder existing regulations, persons

who generate solid waste are notspecifically required to test their wastesto determine whether they exhibit thecharacteristic of EP toxicity or any othercharacteristic. Instead, solid wastegenerators are required to make adetermination as to whether or not theirwastes are hazardous (40 CFR 262.11).

If a waste is found to be excludedfrom regulation under § 261.4, or if it isfound to be a listed hazardous wasteunder subpart D of 40 CFR part 261, nofurther determination of hazardousnessis necessary. On the other hand, if awaste is neither excluded nor listed, thesolid waste generator must determinewhether it exhibits any of the hazardouswaste characteristics in subpart C'of 40CFR part 261. This determination may'be made by either testing the waste orapplying knowledge of the waste, theraw materials, and the processes used inits generation.

If a waste is determined to behazardous, the generator must keeprecords establishing the basis for thatdetermination (40 CFR 262.40(c)). These

records must be maintained for at least3 years after the generator no longerhandles the waste in question. Neitherof these recordkeeping requirements,however, applies to solid wastegenerators who do not generatehazardous wastes.- Other provisions in the hazardouswaste regulations make generatorsresponsible for knowing the propertiesof their wastes and for documenting thatknowledge. For example, generatorswho declare that their wastes arehazardous must nevertheless havesufficient knowledge of their wastes tocomplete the Uniform Hazardous WasteManifest, to use proper labels,containers, and placards, and to satisfyall applicable reporting andrecordkeeping requirements (see 45 FR12728, February 26,'1980). In addition, allgenerators of hazardous waste arerequired under 40 CFR part 268 todetermine whether their wastes arerestricted from land disposal.

2. Changes ConsideredIn the June 13, 1986 proposal, EPA

expressed concern that the currentsystem for determining whether a solidwaste is hazardous may be inadequateto ensure that wastes are characterizedproperly as hazardous or nonhazardous.Because of the importance of accuratehazard determinations to the RCRAsubtitle C program, the Agencydiscussed the possibility of requiringsolid waste generators to test theirwastes periodically.

In the proposed rule, EPA identifiedthree general approaches that might beadopted in the TC final rule. In the firstapproach, the Agency would retain thecurrent approach, allowing generators torely on their knowledge of materials andprocesses used in generating wastes asa basis for their determination. In thesecond approach, EPA would require thetesting of wastes, at a frequencyspecified by regulation. Finally, in thethird approach, the Agency wouldrequire testing but without specifying aparticular testing frequency. Under thisthird approach, generators would berequired to develop an appropriatetesting frequency, based on Agencyguidance, and to document the basis fortheir choice.

Commenters were heavily divided onthe issue of testing and recordkeepingrequirements. Many commenters,including waste management firms anda few generators, favored mandatorytesting of solid wastes. Most of thesecommenters argued that generatorstypically lack sufficient information todetermine accurately the composition oftheir wastes without testing. Indeed, onecommenter claimed that with 52

constituents regulated at the part-per-million level or lower, a generator couldnever be sure whether a waste exhibitsthe TC without performing the TCLPtest. The commenters concluded thattesting is the only reliable method forensuring that potentially hazardouswastes are properly identified andmanaged.

A few commenters offered somewhatdifferent reasons for supporting testingrequirements. For example, somecommenters pointed out that mandatorytesting would facilitate EPAenforcement efforts. Others claimed thatmandatory testing would reduceuncertainty by making it clear togenerators precisely what EPA expectsof them with respect -to performinghazardous waste determinations.

Another group of commenters,however,, opposed the imposition of aformal testing requirement. Thesecommenters argued that mandatorytesting would place an inordinateburden on the regulated communitywithout providing significant benefit forhuman health and the environment. Inparticular, the commenters claimed thatmandatory testing is -ilikely to identifywastes that were improperlycharacterized as nonhazardous whengenerators relied exclusively on theirknowledge. According to thesecommenters, generators rely on theirknowledge only when the wastes theyproduce are clearly hazardous or clearlynonhazardous. Whenever uncertaintyexists, these commenters stated,generators either declare their wasteshazardous or perform appropriate tests.The commenters emphasized that thiscautioned response results fromgenerators' liability for making incorrectdeterminations, regardless of whetherthey test their wastes. The commentersconcluded that requiring testing of allwastes would deplete resources andplace a strain on limited laboratorycapacity.

The Agency recognizes that there aremany difficult issues related to theimposition of a testing requirement, bothfor the Toxicity Characteristic and theother hazardous waste characteristics.While the Agency believes that a testingrequirement could improve the Agency'senforcement tools, the Agency believesthat the current requirements forhazardous waste determinations are notineffective because many generators dohave sufficient knowledge to make adetermination without a test. TheAgency further believes that liability forincorrect determinations provides astrong incentive for not misclassifyinghazardous wastes as non-hazardous.Although EPA thinks that the current

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system set forth in 40 CFR 262.11 iseffective, the Agency believes thatimposing a testing requirement doeshave some merit, in that it couldincrease the accuracy of determinations,could clarify the responsibilities ofgenerators, and could facilitatecompliance monitoring.

The Agency will continue to evaluatethe comments on this issue as well asexplore other options for a testingrequirement. At present, however, theAgency is not yet ready to go forwardwith a testing requirement based on anyof the options it has evaluated thus far.Should the Agency decide that anappropriate approach is available, it willpropose and solicit comment upon thedetails of that approach in a separate -rulemaking. In the meantime, theAgency believes that the existingdetermination requirement (as specifiedat 40 CFR 262.11), as well as the liabilityfor incorrect determinations, is effectiveand practical.

H. Applicability to Wastes Managed inSurface Impoundments

As discussed above, in response tothe proposed TC, EPA received manycomments questioning the validity ofapplying the TC to wastes, includingwastewaters, likely to be managed insurface impoundments. In response tocommenters' concerns, on May 18.1987,EPA published a Supplemental Notice ofProposed Rulemaking in the FederalRegister, which requested commentsand data on several issues related to theregulation of wastes managed in surfaceimpoundments under the TC rule. TheAgency also requested comment(assuming such an approach) on: (1) Thecriteria to be used to determine whetherthe surface impoundment scenarioshould apply to a particular waste, (2)the point at which concentrationmeasurements should be made (e.g., atthe point of generation or within theimpoundment), and (3) how multiplesurface impoundments should behandled under the TC rule.

Comments received in response to thenotice concerning the surfaceimpoundment management scenario aresummarized and addressed in sectionII.A.2.c. Comments received in responseto the notice, which addressed samplingpoint and multiple impoundment issues,are discussed below.

1. Sampling Point

In the May 18, 1987 notice, EPArequested comments on whetherevaluations of wastes managed insurface impoundments should be basedon measurements of the concentration inthe impoundment or at the inlet to theimpoundment. In response, some

commenters supported sampling at theinlet to the impoundment and stated thatsampling the waste within theimpoundment is not only contrary toCongressional intent, but conflicts withEPA's own regulations that require thedetermination of hazard to be made atthe point of generation.

Other commenters, however, arguedthat wastes should be sampled withinthe impoundment or that theimpoundment effluent should besampled. Many of these commentersargued that measuring theconcentrations in the impoundmentmore accurately represents theconcentrations of hazardousconstituents that pose a threat to groundwater. Some commenters argued thatevaluation of hazard should be based onimpoundment effluent becauseconcentrations of the wastewaterswithin the impoundment areapproximately the same as theconcentrations in the impoundmenteffluent.

If the Agency were to allow personsto make their determinations on thewaste in the impoundment, it wouldraise questions that the Agency has notyet evaluated completely nor takencomment on. For example, in thissituation, should the Agency actuallyrequire testing; if so, how often andwhat should be tested? Would such aresult allow persons to land dispose ofwastes that (but for the point of hazarddetermination) would be hazardous,contrary to Congressional intent? Wouldsuch a result allow persons to treatwastes without a permit and thus beinconsistent with Congressional intent?EPA concedes that, for some activities(e.g., closure), leachate quality may bemore appropriately assessed bymeasuring concentrations at multiplesites within the impoundment.

The current rules require that thedetermination of whether a waste Ishazardous be made at the point ofgeneration (i.e., when the wastebecomes a solid waste). (A waste mustbe a solid waste before it can beclassified as a hazardous waste underRCRA.) EPA believes that determinationof the regulatory status of a waste at thepoint of generation continues to beappropriate, especially since the Agencyis not developing a separatemismanagement scenario or set ofregulatory levels for wastewaters. To beconsistent with other hazardous wasteregulations and until the Agencyaddresses the above questions, EPA isretaining the existing approach ofrequiring sampling at the point ofgeneration.

2. Multiple Surface Impoundments

In the May 18, 1987 notice, EPArequested comment on how multiplesurface impoundments or "treatmenttrains" should be handled under the TCrule. Some commenters favoredregulating all surface impoundments in atreatment train as a single unit-if thefirst impoundment treats a hazardouswaste, all impoundments would berequired to comply with the RCRAregulations for hazardous wastetreatment facilities. Other commenters,however, suggested that eachimpoundment should be regulatedindividually. Still other commentersstated that owners and operators shouldbe required to determine whether themost upstream surface impoundment istreating wastes that exhibit the TC, butthey should only be required to evaluatedownstream impoundments If anupstream impoundment exhibits the TC.

As discussed above, the Agency hasdecided not to develop a separateregulatory scheme for surfaceimpoundments. Thus, the Agency willcontinue toregulate all surfaceimpoundments as individual units andwill not pursue any of the other optionsdiscussed by commenters. Currently,under 40 CFR part 261, each surfaceimpoundment in a series of multiplesurface impoundments is regulatedseparately. If a surface impoundmentreceives or generates a hazardouswaste, the owner or operator of theimpoundment is required to comply withthe RCRA regulations governinghazardous waste treatment, storage, anddisposal facilities. On the other hand, ifa downstream impoundment is nottreating or generating acharacteristically hazardous waste andupstream units have not managed, listedwastes, then the downstream unit is notsubject to RCRA subtitle Crequirements.

I. Relationship to Other RCRARegulations

1. Hazardous Waste IdentificationRegulations

a. Hazardous Waste Listings. Underthe June 13. 198, proposal, thehazardous waste listings in subpart D of40 CFR part 261 would not be affected.All the listings would remain in effect,including those listings that were basedon the presence of TC constituents. It isEPA's intention that the hazardouswaste listings would continue tocomplement the revised TC as they hadthe EPTC.

A number of commenters, however,argued that the TC should supersedecertain hazardous waste listings. In


Federal Register / Vol. 55, No. 61 / Thursday. March 29,. 1990 / Rules and Regulations

particular,. they suggested that the TCshould be the only basis for regulatingwastes, that have been identified ashazardous solely because of thepresence of a TC constituent. Such anapproach, according to the commenters,would establish a more rational basisfor identifying hazardous wastes.Wastes failing the TC test would beregulated as hazardous. wastes, whetheror not they have previously been listed,because they have demonstrated thepotential to pose a threat to humanhealth and the environment. Wastespassing the TC test. in contrast, wouldnot be subject to subtitle C regulation.The commenters claimed' that, bydefinition, if the extract from a wastethat was listed because of the presenceof a TC constituent does not contain theconstituent in a concentration greaterthan or equal to the regulatory level thewaste can safely be managed at asubtitle D facility.

EPA does not agree that the TCrevisions justify elimination of any ofthe hazardous waste listings. TheAgency has consistently maintained thatindividual waste streams may be listedregardless of whether the waste. isdefined as hazardous, by the TC.Exhibiting a characteristic canconstitute the basis for listing a waste.In fact, prior to today's action,approximately 25 listings were based onthe presence of metals or pesticidescovered by the EPTC.

There are a number of reasons forcontinuing this approach. First, listedwastes frequently contain hazardousconstituents other than the ones cited inAppendix VII of 40 CFR part 261 as thebasis for the listings. It is for this reasonthat Congress directed EPA, inevaluating delisting petitions, to,consider constituents other than thosefor which the. wastes were Iisted'assuming that there is a reasonablebasis to believe that such constituentsmight render the wastes hazardous (seeRCRA section 3001(f)). In many cases,.the additional hazardous constituentsthat are present in a waste may not beon the list of TC constituents. Thelistings may therefore serve to identifywastes that pass the TC test but arenevertheless hazardous. Removingwastes from a hazardous, waste listingwithout an evaluation of additionalconstituents would appear to beinconsistent with the intent of section3001(f.

Another reason for retaining thehazardous waste listings i& that TCconstituents may continue to pose athreat to human health and theenvironment even when they arepresent in concentrations lower than the

regulatory levels. The re2gulatory levelshave not been designed to address theproblems of phytotoxiclty, aquatictoxicity, or bioaccumulation potentiaLMoreover, they have not been designedto identify the full range of wastes thatmay be toxic to human beings. Instead,,the characteristic levels have beenestablished at concentrations wherethere is a high degree of certainty thatany wastes with constituents at levelsequal to, or exceeding the regulatorylevels pose a potential threat to humanhealth. Individual wastes may continueto be hazardous, despite the fact thatthey may contain TC constituents inconcentrations below the regulatorylevels. This is particularly true forwastes that have the potential to beexposed to more aggressive leachingconditions than those modeled in theTCLP. As a result,. EPA believes thatwastes previ'ously listed as hazardousshould continue to be consideredhazardous, whether or not they exhibitthe characteristic.

b. "Mixture" and "Derived From"Rules. Because the TC will notsupersede the listings for hazardous-wastes, it also will not affect theregulatory status of wastes that arehazardous by virtue of the "mixture"rule of 40 CFR 262.3(a)(2)(ivl or the"derived from" rule of 40 CFR 261.3(c).The "mixture" rule provides that anymixture of a listed hazardous waste anda solid waste is itself a RCRA hazardouswaste.8 The "derived from" rule statesthat any waste derived from thetreatment, storage, or disposal of a listedhazardous waste is hazardous.

Several commenters contended thatthe current regulatory schemeencompasses wastes that contain deminimis quantities of leachable organic:chemicals. The commentersacknowledged that mixtures andtreatment residues posing insignificantthreats to human health and theenvironment may be excluded fromregulation through the delisting process.However, they claimed that delisting isunduly expensive, time-consuming,. and,in some cases, impractical. Thecommenters suggested as anl alternativethat mixtures and treatment residuesfrom listed wastes containing TCLPconstituents not be consideredhazardous unless they fail the TC test.They contended that this approachwould adequately protect human healthand the environment. Moreover, it

3 The exception, to this rule' is, a mixture of solidwaste and a waste that is listed solely because itexhibits a characteristic of hazardous waste. if sucha mixture does not exhibit any characteristic ofhazardous waste, the mixture is not defined, ashazardous 140 CFR 26%.3(a)(2)(iiill.

would be "self-implementing," in thesense that it would eliminate the needfor the current process of petitions andAgency review for delisting.

EPA recognizes that the "mixture"and "derived from" rules may createsome inequities by including wastes thatcontain very small amounts ofhazardous wastes that have been mixedso as. to render them nonhazardous.However, the Agency has consistentlymaintained that the mixture and: derivedfrom rules are an appropriate regulatoryapproach for dealing with. wastemixtures and treatment residues.

When the rules were promulgated in1980, EPA stated that it was essential toregulate waste mixtures to preventgenerators from evading subtitle Crequirements by simply, co-minglinglisted wastes with nonhazardouswastes. The Agency also determinedthat because of the infinite potentialcombinations of listed wastes and otherwastes, it was unable at that time todevise any workable, broadly applicableformula that was capable ofdistinguishing between hazardous andnonhazardous mixtures. The Agencyacknowledged that the "mixture"' rulemight be overly broad, but noted thatgenerators could! avoid any inequitieseither by segregating their wastes or byobtaining a waste-specific exclusionunder the delisting program (see 45 FR33095, May 19, 1980).

EPA also believed that it wasimportant to regulate wastes from thetreatment, storage, or disposal of listedhazardous wastes on the basis thatthese "derived from" wastes mightthemselves be hazardous. Once again,however, the Agency found that becauseof the large number of listed wastes, andtreatment processes (some of whichintroduce, new hazardous constituentsinto the treatment residues), it wasunable to prescribe standards that couldproperly distinguish between hazardousand nonhazardous residues. (It shouldbe noted that the definition of treatmentis not confined to rendering a wastenon-hazardous', but also includes anymethod designed to change the nature ofa waste to render the waste (1) lesshazardous; (2) safer to transport, store,or dispose; (3) amenable for recovery: or(4) reduced in volume (see 40 CFR260.10).) Therefore, the Agencyconcluded that wastes generated duringthe treatment of listed, wastes should bepresumed to be hazardous. Delistingwas provided as the mechanism forexcluding these wastes from subtitle Cregulation (45 FR 33096, May 19, 19810.

EPA is sympathetic to thecommenters concerns regarding use ofdelisting to exclude wastes, that are

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hazardous under the "mixture" and"derived from" rules. The Agency doesnot believe, however, that thealternative suggested by thecommenters (i.e., relying on the TC toregulate mixtures and treatmentresidues) would adequately protecthuman health and the environment. Asnoted above, wastes that pass thecharacteristic test may nevertheless behazardous, either because they containlisted constituents at concentrationsbelow the TC regulatory levels but atlevels and under circumstances thatnevertheless render the wastehazardous or because they containhazardous constituents that are notcovered by the TC rule. As noted above,the TC regulatory levels are notthreshold levels defining all hazardouswaste, but are levels that are set toclearly define hazardous waste. Wastescontaining constituents falling belowthese levels may still present a hazard inmore limited situations.

Nevertheless, the Agency recognizesthat some inequities may result by theapplication of the "mixture" and"derived from" rules to certain dilutelisted wastes. The Agency therefore is.considering proposing an amendment tothe definition of hazardous waste whichwould establish self-implementing deminimis exemption levels for hazardousconstituents found in listed wastes.Listed wastes that meet these exemptionlevels would no longer be listedhazardous wastes and thus would notneed to be managed as hazardouswastes unless they'exhibit a hazardouswaste characteristic.

c. Mixture Rule Exemption. Themixture rule under 40 CFR 261.3(a)(2)(iv)provides an exemption from RCRAsubtitle C regulation for mixtures ofwastewaters and certain listed spentsolvents. The mixture rule exemption isapplicable only if the maximum weeklyusage of the solvents (other thansolvents that can be demonstrated notto be discharged to wastewater) dividedby the average weekly flow ofwastewater does not exceed specifiedvalues. The mixture rule exemption doesnot apply to wastewaters that exhibit acharacteristic of hazardous waste or towastewaters that contain listedhazardous wastes not specified in themixture rule exemption.

A number of commenters claimed thatthe proposed TC conflicts with themixture rule exemption. Thecommenters noted that the mixture ruleexemption levels are higher than thecorresponding TC regulatory levels forsolvent constituents. Because of thisdifference in regulatory levels, thecommenters stated that the proposed TC

rule will bring large quantities ofcurrently exempted wastewaters intothe hazardous waste managementsystem. In effect, the commenters arguedthat the TC rule will revoke the mixturerule exemption. Commentersdisapproved of this result, stating thatthe mixture rule exemption waspromulgated in recognition that smallamounts of certain spent solvents areoften most efficiently managed by beingdischarged to a plant's wastewatertreatment system and that this methodof management does not pose risks tohuman health and the environment.

EPA acknowledges that the TC rulemay bring some currently exemptedwastewaters into the subtitle Cregulatory system; however, the mixturerule exemption is an exemption from thehazardous waste listings, not thecharacteristics. Thus, there is noinconsistency between this rule and themixture rule exemption. In addition, itshould be noted that the TC regulatorylevels are based on state-of-the-arttoxicological data and risk assessmentmethodologies. Consequently, EPAbelieves that the TC regulatory levelsare the best measures available toidentify wastewater mixtures that posea threat to human health and theenvironment. In contrast, the mixturerule exemption levels are based uponless current risk information.

Even though some wastewaterspresently covered by the mixture ruleexemption will become hazardouswastes as a result of the TC rule, EPAbelieves that the exemption willcontinue to serve an important purposeby, ensuring that mixtures ofwastewaters and certain listed spentsolvents will not be consideredhazardous unless they exhibit acharacteristic of hazardous waste. Toclarify the mixture rule exemption andmake it more consistent with currentrisk information, EPA is consideringproposing in the future that-the mixturerule exemption levels be reduced so thatthey are equivalent to the TC regulatorylevels.

d. Delisting. While the June 13, 1986proposal did hot specifically address theeffect that the TC might have on thehazardous waste delisting programunder 40 CFR 260.22, a number ofcomments were received claiming thatthe TC rule would be inconsistent withexisting EPA policies regarding case-by-case exclusions. In the August 1, 1988proposal, however, the Agency solicitedcomment on the use of the EPACMLmodel in the delisting program.

The commenters noted that eachmajor element of the delisting programis different from the corresponding

element in the original TC proposal. Forexample, the chronic toxicity referencelevels that are used to establish "nohazard" levels under the delistingprogram appear to differ from the levelsthat were used to establish the proposedTC regulatory standards. In addition, thedelisting program uses (as appropriate)a different ground water transportmodel (i.e., the Vertical and HorizontalSpread (VHS) Model), which generatesgeneric DAFs rather than compound-specific factors. Finally, the delistingprogram employs (as appropriate) theOrganic Leachate Model (OLM) ratherthan the EP or the TCLP to determinethe degree to which various organicconstituents are likely to leach fromsolid wastes. The commenters urged theAgency to use the same reference levels,DAFs, and leaching procedures in boththe characteristic and delistingprograms. A few commenters expresseda particular preference for adopting thedelisting elements as part of the revisedTC.

There were a number of differencesbetween the various elements of theproposed TC and the correspondingelements in the delisting program.However, regarding Chronic ToxicityReference Levels, the only differencebetween the levels used in the delistingprogram and those in the TC final rule isthe use of different risk levels for thecarcinogens (i.e., delisting uses a moreconservative risk factor of 10 - 6 forcarcinogens, compared to the use of a10- 5 risk factor in the TC rule). Many ofthe differences between the chronictoxicity reference levels used in the TCrule and those in the delisting programhave been eliminated as a result ofdecisions concerning risk levels andapportionment. Furthermore, the health-based levels used in the delistingprogram and in the TC rule have beenupdated to incorporate recent Agencyevaluations (see 53 FR 18024).

EPA believes -that the risk factorsbeing used for each program areappropriate, and does not think that risklevels used to set regulatory levelsshould necessarily be the same in thetwo programs because each serves aseparate purpose. Delisting evaluatesthe hazard posed by specific individualwastestreams that have been listed ashazardous. Characteristics identifybroad classes of clearly hazardouswastes; specific wastes that may pose asubstantial identified hazard in a lowerrisk range may be listed as hazardous.As discussed below, EPA believes it isappropriate that the delisting program is,in certain cases, more stringent than thecharacteristic program.



A number of commenters focused, onthe overall stringency of thecharacteristic and delisting programs. Inparticular, the commenters stated thatthe proposed TC regulatory levels weresometimes greater than and sometimesless than the concentration standardsused by the Agency's delisting programin determining when listed wastes mayproperly be managed in subtitle Dfacilities. Most of the commentersargued that EPA, in. the interest ofconsistency, should adopt the sameconcentration standards under thecharacteristic and delisting programs.Other commenters. however, urged theAgency to establish higherconcentration standards under the'revised characteristic. The latter groupof commenters noted that characteristicsare designed to identify broad classes ofsolid wastes that are "clearly"'hazardous, while listings are designed toidentify wastes that may not exhibit acharacteristic, yet are neverthelesshazardous. The commenters concludedthat, in light of the different functions oflistings and characteristics, it should be,more difficult for a waste to pass thedelisting standards (Le., to be. eligible! fordelisting) than for the same, waste topass the characteristic test.

EPA does not agree with thosecommenters who argued that theAgency must use the sameconcentration standards in thecharacteri3tic and delisting programs or,that the concentration standards forcharacteristics must be higher thanthose for delisting., These programs havevery different purposes. Whilehazardous waste, characteristic levels;are those: equal to. or above which awaste is clearly hazardous: due to a,particular property, delisting levels are:those below which a waste, is nothazardous. Thus, it is reasonable thatthese two levels may or may notcoincide. Delisting decisions are basedon an extensive evaluation of aparticular waste which requires specificinformation on the waste. Thecharacteristics approach to defining ahazardous waste is much more broad.Only one mismanagement scenario. isused and it is based on "reasonableworse-case" assumptions resulting, in a"generic" regulatory level to, be applied,to all solid waste. And,. of course,section 260.22 of the RCRA regulations'specifies that a waste may not bedelisted if it exhibits a characteristic ofhazardous waste (e.g., the characteristicof EP toxicity . Thus, the delistingprogram could never be less stringentthan the characteristic program.

In regard to the use. of differentmodeis in the 'delisting and

characteristic programs, in the August 1,1988 Federal Register notice, the Agency.specifically solicited comment on theuse of the Toxicity Characteristicsmodel (EPACML) in place of the modelcurrently used in the delisting program(the VHS model). All of the commenterssupported the use of EPACML instead ofthe VHS model in the delisting program,although one commenter supported thisonly if it would not add complexity and,thereby increase the time required fordelisting petition evaluation. Anothercommenter stated that the EPACMLmodel should be used in the delistingprogram but that petition evaluationsshould not be restricted to the use of anysingle specific model. Finally, several ofthe commenters stated that the Agencyshould present details as to how theEPACML model would be used fordeli'sting in a separate Federal Registernotice.

In response to these comments, theAgency will use the EPACML model andthe TCLP in the delisting program. Also,as. suggested, the Agency will explainhow the model and the TCLP will beused in a future Federal Register notice.

A few commenters expressed concernabout the applicability of the TC towastes that have previously beendelisted. The commenters argued thatonce EPA has ruled (through the waste-specific delisting process) that aparticular waste stream poses no threatto human health and the environment,the Agency should be barred from usinga generic rule to declare the same wasteas being "clearly" hazardous. One!commenter claimed: that it would beespecially unfair to alter the regulatorystatus of a waste stream after the personmanaging it has been granted anexclusion and has acted in reliance onthat exclusion (e.g., by changing the ,

production process or wastemanagement practices).

EPA has consistently maintained thatwastes "excluded" from subtitle Cregulation under the delisting programmay nevertheless be hazardous if theyexhibit a characteristic of hazardouswaste (see 40 CFR 260.22). While the TCrule will apply to previously delistedwaste, EPA does not, in general, expectthat such wastes will become hazardousbecause of application of the revisedTC. The Agency believes that, becausedelisting levels are more stringent thanthe final TC levels, the. impact of the TCrule on previously delisted wastes willbe minimal. Nevertheless, if a previouslydelisted waste exhibits the, TC, it willagain be subject to subtitle, Crequirements (i.e., delisted wastes aretreated no differently than any othersolid waste).

2. Land Disposal Restrictions

a. Risk Levels and Frequency Interval.The approach used to developregulatory levels in the proposed TCrule was similar to the original approach.suggested for developing treatmentstandards in the proposed LandDisposal Restrictions: (LDR1 rule (51 FR1602, January 14, 1986). Both proposalsbegan with health-based concentration;thresholds at the point of exposure andused subsurface fate and transportmodels to back-calculate allowableconstituent concentrations in theleachate. In the June 13, 1986 TCproposal, the Agency- requestedcomments on whether the risk levelsand cumulative, frequency level used inthe TC should be the same as those usedto develop the treatment standards inthe proposed LDR rule.

Several commenters supported the useof different risk levels and cumulativefrequency levels in the two proposals.These commenters stressed thatdifferent statutory mandates for the tworules and the entirely different functionsof the TC regulatory levels and the LDRtreatment standards warranted differentapproaches. However, othercommenters contended that thefrequency level and risk levels in the TGrule should be the same as or morestringent than those used in the LDR.proposal. Some of these commentersargued that the more stringent risklevels and frequency level in the LDRproposal provided a more appropriatedegree of protection for human healthand the environment than thecorresponding levels and frequencyinterval in the TC proposal.

The issue of consistency of risk levelsand frequency level for the TC and theLDR program, is now moot. The LDRfinal rule (51 FR 40572, November 7,1986) abandoned the use of screeninglevels based on risk methodology andsubsurface fate and transport modeling,and promulgated an approach, toestablishing treatment standards basedentirely on technology-based standardsexpressed as Best DemonstratedAvailable Technology {BDAT). Today'srule continues to be based upon health-based concentration levels and dilution./attenuation factors, the values for whichare based upon the predictions of asubsurface fate and transport model.

b. Treatment Standards for TCWastes. Under RCRA section 3004(g)(4',EPA is required to make an LDRdetermination for all TC wastes within 6months of today's action, as discussedin the following section. Severalcommenters were concerned' that theLDR treatment standards that will

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eventually be established for the TCwastes may be inconsistent with TCregulatory levels. Some of thesecommenters noted that the proposedLDR treatment standards for listed spentsolvents were in many cases lower thanthe proposed TC regulatory levels forthe identical constituents in unlistedcharacteristic wastes. The commentersfeared that if LDR treatment standardsare applied to unlisted TC wastes in thesame manner as they are applied tosimilar listed wastes, the characteristicwastes may require treatment to belowthe TC level before subtitle C landdisposal is permissible. This means thatunlisted wastes no longer exhibiting theTC must continue to be managed ashazardous wastes: Some commenterswho voiced concerns over potentialdifferences between TC regulatorylevels and LDR treatment standardssuggested that there should be a clearcontinuum of regulatory levels, with thehigher standards being those that deema waste hazardous in the first place (i.e.,the TC regulatory levels).

Wastes deemed hazardous under theTC will not immediately become subjectto the LDR program on the effective dateof the TC rule, except perhaps byoperation of the California Listrestrictions (i.e., halogenated organiccompounds are subject to the LDR ifthey exhibit a characteristic, see 52 FR25770, July 8, 1987). However, theAgency has not yet determined whetherthe existing LDR California Listrestrictions should be applicable tonewly identified TC wastes. The Agencyspecifically requested comment on theappropriateness of applying theCalifornia List prohibitions to newlyidentified hazardous wastes in theNovember 22, 1989 proposed rule for the"Third Third" of scheduled wastes (54FR 48499). The Agency will fully addressthis issue as part of the "Third Third"final rule.

Since the Agency is not todayproposing LDR treatment standards forthe TC wastes, the Agency believes thatit is more appropriate to address thesecomments when the LDR treatmentstandards are proposed. However, inresponse to comments that proposedtreatment standards for listed solventswere lower than proposed TC levels, theAgency would like to point out that thetreatment standards for TC wastes willnot necessarily be the same as thecorresponding LDR treatment standardsfor spent.solvents. Indeed, if the TCwastes belong to a different treatabilitygroup, one can expect that the treatmentstandards will be different.

c. Schedule for LDR Determinations.For wastes already listed or identified at

the time of enactment of HSWA, theAgency must make LDR determinationsaccording to the schedule set forth inRCRA section 3004(g)(4). If EPA fails tomake the determinations by theestablished schedule, the wastes areautomatically subject to the landdisposal restrictions on the scheduleddate. EPA must also make LDRdeterminations for all wastes that areidentified or listed as hazardous afterNovember 1984 (when HSWA wasenacted) within six months after thewastes are identified or listed.

On November 22, 1989 (54 FR 48372),EPA proposed treatment standards forthose wastes that exhibit the EPTC, aswell as any of the other characteristics.Upon the effective date of today's rule,the TC will include the 14 EPTCconstituents in addition to the 25organics, and the TCLP will replace theEP. EPA proposed that the BDAT levelsfor wastes that exhibit the EPTC for the14 constituents remain the same whenthe TC becomes effective. By May 8,1990 the Agency will establish the finalBDAT levels for the 14 constituentcurrently identified by the EPTC. Newlyidentified TC wastes are subject to thesix-month listing deadline. However,wastes are not automatically prohibitedfrom land disposal if EPA fails to makethis required determination within sixmonths.

Some commenters argued that the six-month-deadline would accelerate theLDR determinations for listed wastesthat contain TC constituents. Forexample, some commercial chemicalproducts are currently scheduled to bereviewed by May 8, 1990 (51 FR 19300,May 28, 1986). However, these wastesalso may exhibit the TC. Commenterswere concerned that these wastes maybe subject to the six-month deadline andclaimed that this would effectivelyaccelerate the determinations in amanner that would be contrary toCongressional intent.

Wastes that are newly identified ashazardous by today's rule will besubject to the six-month deadline forLDR determinations. However, even ifEPA were to complete LDRdeterminations for TC wastes beforeMay, 1990, the Agency disagrees withcommenters that this has the potentialto accelerate the determinatios in amanner that would be contrary toCongressional intent. The dates set forthin RCRA section 3004(g)(4) are deadlinesby which EPA must make LDRdeterminations or the wastes areautomatically restricted from landdisposal. EPA is in no way prevented ordiscouraged by the statute from makingLDR determinations before any of its

deadlines (RCRA section 3004(g)(5),"Not later than * *"'). Indeed, otherdeterminations are being made ahead ofschedule; the final rule for restricting"second third" wastes includestreatment standards and prohibitions forsome "third third" wastes (54 FR 26594).

3. RCRA Corrective Action and ClosureRequirements

Today's rule will have no direct effecton either the action levels of RCRAcorrective action or the cleanupstandards of RCRA closurerequirements. However, to the extentthat the TC brings more facilities underthe RCRA program as hazardous wastemanagement facilities, additionalfacilities will be. newly subject to thesubtitle C corrective action and closurerequirements.

Although the corrective actionprogram under subtitle C addressesremediation of releases of hazardousconstituents from waste at facilitiessubject to RCRA permitting, the TClevels will be neither action levels (i.e.,concentrations that, if exceeded, signalthe need for corrective action) norcleanup standards. Rather, correctiveaction, as a process, encompassestrigger levels and cleanup standards thatare developed from site-specificinformation gathered during theinvestigatory and evaluative phases ofthe process (i.e., the RCRA FacilityInvestigation and the CorrectiveMeasures Study).

Thus, the levels or concentrationsassociated with today's TC rule arelargely independent from levelsassociated with corrective action.Similarly, the closure requirements areunaffected by today's rule. The TC is notused to determine whether a facility hasmet the requirements for clean closure.However, it must be noted that solidwastes generated as a result Ofremediation of releases or in pursuanceof closure requirements that exhibit theTC must be handled as a hazardouswaste.

4. Minimum Technology Requirements

a. Applicability. HSWA added section3004(o) to RCRA which imposesminimum technology requirements onowners and operators of certain landfillsand surface impoundments seekingpermits. HSWA also added a newsection 3015 imposing similarrequirements on certain interim statuswaste piles, landfills, and surfaceimpoundments. Finally, HSWA section3005(j) requires surface impoundmentsto be retrofitted to meet minimumtechnology requirements. EPA codifiedthe statutory language in the Agency's



Codification Rule promulgated on July25, 1985 (50 FR 28705). Facilities that willface new RCRA regulation following thepromulgation of the TC will need tocomply with the minimum technologyrequirements in order to remain inoperation.

b. Scope of Minimum TechnologyRequirements-1. Permitted Facilities.Section 3004(o)(1)(A) requires that afterNovember 8, 1984, certain landfills and ,,surface impoundments must meetminimum technology requirements. Theminimum technology requirements forlandfills and surface impoundmentsappear in 40 CFR 264.301(c) and264.221(c), respectively. They require theowner or operator of each new unit andeach replacement unit or lateralexpansion of an existing unit to installtwo or more liners and a leachatecollection system between and, forlandfills, above.the liners.

2. Interim Status Facilities. Section3015 of RCRA requires that certainwaste piles, landfills, and surfaceimpoundments meet minimumtechnology requirements. The minimumtechnology requirements for interimstatus waste piles, landfills, and surface,impoundments appear in 40 CFR 265.254,265.301, and 265.221, respectively. Theyrequire that the owner or operator ofeach new unit, replacement of anexisting unit, or lateral expansion of anexisting unit that is within the areaidentified in the part A permit,application install liners and a leachatecollection system or equivalentprotection. Existing surfaceimpoundments (i.e., surfaceimpoundments regulated under subtitleC prior to November 8, 1984) had to beretrofitted to meet the minimumtechnology requirements by November8, 1988.

c. Compliance with MinimumTechnology Requirements. Facilities orunits newly regulated as a result of theTC will have to meet the minimumtechnol6gy requirements of sections3004(o) and 3015 if and when they add anew unit, replace an existing unit, orlaterally expand an existing unit.Surface impoundments must complywith the retrofitting requirement insection 3005(j)(6)(A), which requires the -owner or operator of a newly-regulatedsurface impoundment to retrofit thatimpoundment 4 years from the date ofpromulgation of the additional listings orcharacteristics, that made it subject toregulation. Thus, surface impoundmentsthat becomre regulated under subtitle Cbecause of the TC will need to meet theminimum technology requirements onMarch 29, 1994. (However, retrofittingmay be expedited due to the minimum

technology requirements imposed underthe capacity variance for land disposalunder section 3004.) This extensionapplies only to those impoundments thatcontain solely the newly listed/characteristic wastes. Anyimpoundments that already containedlisted/characteristic wastes currentlyare subject to RCRA regulations,including the minimum technologyrequirements. Other existing landdisposal units (besides surfaceimpoundments) that already containedwastes that exhibit the TC will notrequire retrofitting unless they areexpanded or are replacement units.

5. RCRA Subtitle D (Solid Wastes)

a. Municipal Waste Combustion Ash.Several commenters requested that ashfrom municipal waste combustion(MWC) units be exempt from regulationunder the TC. Many of thesecommenters argued that the regulationof MWC ash would be in direct conflictwith RCRA section 3001(i), whichprovides that resource recoveryfacilities engaging in MWC "shall not bedeemed to be treating, storing, disposingof, or otherwise managing hazardouswastes." Other commenters indicatedthat the high costs associated withsubtitle C regulation would discourage

"the recovery of energy values fromMSW. They claimed that this resultwould run counter to the clearCongressional intent to encourageresource recovery as a beneficialalternative to the landfilling of MSW.

EPA articulated its position on thescope of section 3001(i) when theAgency codified the 1984 HSWA (see 50FR 28725, July 15, 1985). However, tworecent Court decisions have rejectedEPA's 1985 interpretation. EDF v. City ofChicago, No. 88C769 (N.D. Ill.) (slip op.Nov. 29, 1989) and EDF v. WhgelabratorTechnologies Inc., No. 88Civ.0560 (S.D.N.Y.) (slip op. Nov. 21, 1989). TheAgency is considering the appropriateresponse to these two decisions.

b. Impact on Wastes Excluded fromSubtitle C Regulation. Another group ofcommenters asked for assurances thatthe TC rule would not affect the existingexclusions for specific wastes under 40CFR 261.4(b). One commenter expressedparticular concern about the exclusionfor mixtures of household and othernonhazardous solid wastes. Anothercommenter raised questions aboutapplying the TC to wastes that areusually considered to be non-hazardoussolid wastes. Other commenters focusedon the exemptions for "special wastes,"primarily mining and mineral processingwastes and oil and gas productionwastes. A utility company consortiumaddressed the exemption for wood

treated with arsenic, commonly used asa fungicide for utility poles. Thecommenter noted that cresols andpentachlorophenol, also used asfungicides for wood, are proposed as TCconstituents; the commenter assertedthat the exemption for arsenic-treatedwood should be extended to creosote-and pentachlorophenol-treated wood aswell.

The TC rule will not apply to wastesthat are already excluded from subtitleC regulation under § 261.4(b). Thesewastes will continue to be exempt fromregulation as hazardous wastes, even ifthey would exhibit the TC. Likewise, theTC rule does not add any exclusions tothe applicability of previouslypromulgated hazardous wastecharacteristics. With respect to the issueof creosote- and pentachlorophenol-treated wood, EPA does not at this timeintend to expand the list of exemptionsunder § 261.4(b) to include these wastes.This is discussed further in sectionIII.J.4.b.

It should be noted, however, that thespecial waste exclusions are currentlybeing reevaluated in accordance withthe criteria and procedures mandated byCongress. After completing the studiesrequired by RCRA section 8002, EPAmay determine that one or more specialwastes should be regulated under RCRAsubtitle C (see RCRA section 3001(b)).Such wastes would then be listed or thegenerators required to determinewhether the wastes exhibit a hazardouswaste characteristic.

A few commenters argued that even ifspecial wastes are brought into thesubtitle C system, they should not besubject to the TC. These commentersclaimed that codisposal of specialwastes with MSW is implausiblebecause special wastes, by definition,are generated in very large quantities.The commenters recommended that EPAdevelop a separate mismanagementscenario and leaching procedure forspecial wastes.

At this time, the Agency cannot agreethat the TC should not be applicable tospecial wastes; rather, the applicabilityto these wastes will be determined on acase-by-case basis. If EPA makes adetermination that any special wastesshould be regulated under RCRAsubtitle C, the Agency will at that timemake a separate determinationconcerning the applicability of the TC tosuch wastes.

6. RCRA Subtitle I (UndergroundStorage Tanks)

a. Scope of the Underground StorageTank Program. Subtitle I of RCRAprovides for the establishment of a

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regulatory program for undergroundstorage tanks containing "regulatedsubstances." Regulated substances aredefined under RCRA section 9001(2) as(1) petroleum and (2) hazardoussubstances listed under section 101(14)of the Comprehensive EnvironmentalResponse, Compensationl, and LiabilityAct (CERCLA or Superfund), excludinghazardous wastes regulated undersubtitle C of RCRA.

Except as discussed below, today'saction will change the regulatory statusof TC wastes that were previously.subject to RCRA subtitle I. Becausethese wastes will be RCRA hazardouswastes, they are excluded fromregulation under subtitle I (see 40 CFRpart 280.10(b)(1)). For this reason,underground storage tanks that containTC wastes will be subject to the subtitleC tank requirements rather than thosepromulgated under subtitle I.

b. Deferral for Petroleum-Contaminated Media and DebrisSubject to Part 280 Corrective ActionRequirements. As part of itsunderground storage tank (UST)program, the Agency has recentlypromulgated regulations which addressreleases from USTs containingpetroleum (see 53 FR 37082, September23, 1988 and 53 FR 43322, October 26,1988). Among other requirements, theserules require petroleum UST owners andoperators to install leak detection, toreport leaks from their tanks and piping,to undertake corrective action toaddress such releases, and todemonstrate financial assurance forcorrective action and third partyliability resulting from such releases.These requirements started going intoeffect in December, 1988, and theAgency estimates that over the next fewyears more than 300,000 petroleum USTreleases will be discovered and besubject to the subtitle I corrective actionrequirements. In addition, the Agencyhas, through cooperative agreements,provided funding to states from theLeaking Underground Storage Tank(LUST) Trust Fund under RCRA to -undertake the necessary responseactions where petroleum UST ownersand operators are unable or unwilling todo so. Hundreds of petroleum USTcleanups have been initiated to dateunder this program.. As noted in the preamble to the finalUST rules, due to the large regulatedcommunity affected by the USTregulations, the UST program is basedon self-implementing requirements andis highly dependent upon voluntarycompliance to attain the environmentalperformance objectives of the program.However, because petroleum contains

several of the hazardous constituents forwhich regulatory levels are beingestablished today (e.g., benzene) someof the petroleum-contaminated mediaand debris may exhibit the ToxicityCharacteristic under today's rule. Whilethe amount and type of media anddebris that may exhibit thecharacteristic at any particular UST sitewill depend upon the petroleum product,soil type, and the size of the release, it islikely that many sites where petroleumUST releases have occurred will containsome media that exhibits the ToxicityCharacteristic. The management of anysuch media and debris would be subjectto subtitle C requirements for hazardouswaste management.

The Agency has insufficientinformation concerning the full impact ofthis rule on UST cleanups, but theinformation available to date suggeststhat the impact may be severe in termsof the administrative feasibility of boththe subtitle C and subtitle I programs.Thus, the Agency has decided to defer afinal decision on the application of theTC to media and debris contaminatedwith petroleum from USTs subject to thepart 280 requirements. The applicationof today's rule to these cleanups will bedelayed while the Agency evaluates theextent and nature of this impact andalternative administrative 'mechanismsfor implementing the UST cleanups inaccordance with subtitle Crequirements. The Agency. believes thatthe UST regulations governing cleanupsat these sites will be adequate in theinterim to protect human health and theenvironment.

The deferral of a final decisionconcerning application of this rule toUST cleanups is necessary for severalreasons. First, while the actual numberof sites and amount of media and debrisat each site'that would exhibit thetoxicity characteristic under today's ruleis unclear, based on a preliminaryassessment, the number and amountcould be extremely high. As notedabove, EPA expects hundreds ofthousands of UST releases to beuncovered in the next few years.Subjecting each of these sites to subtitleC requirements could overwhelm thehazardous waste permitting programand the capacity of existing hazardouswaste treatment, storage, and disposalfacilities. Imposition of the subtitle Crequirements is also likely to delaycleanups significantly and severelydiscourage the self-monitoring andvoluntary reporting essential toimplementation of the UST program.Moreover, the UST cleanup activitiesinvolving the most contaminated mediaand debris are also likely to involve free

product recovery. Free product recoverywould not be subject to subtitle Crequirements because the material beingrecovered is not a waste.

Because of the uncertainties of theimpacts on the UST cleanups as a resultof this rule, including the amount ofcontaminated media that would becomehazardous waste and the type ofmanagement feasible and appropriatefor such waste (i.e., on-site treatment,off-site disposal), EPA cannot determinewhether the application of this rule tothese cleanups will have the severeconsequences on implementation ofthese RCRA programs that preliminaryinformation suggests. Also, because thisissue did not come to the Agency's "attention until late in the developmentof this rulemaking, the Agency has nothad an opportunity to obtain publicinput on this issue, the implications ofthe subtitle C requirements whenapplied to UST cleanups, or anyalternative regulatory mechanisms tomake feasible the implementation ofUST cleanups while meeting subtitle Chazardous waste requirements. Thus,the Agency believes that furtherevaluation of the impacts of applying theTC to soils and ground watercontaminated by petroleum from USTsand subject to the subtitle I program isnecessary in order to determine whetheran exemption for such materials iswarranted or whether additionalregulatory pr administrative changescan or should be made in order to makethe application of the TC to USTcleanups feasible.

In order to make a final decisionconcerning the applicability of this ruleto UST sites, the Agency intends toundertake several activities. First, theAgency will attempt to more specificallydefine the impact of the TC throughstudies of petroleum UST sites, focusingupon the potential hazard from thesesites. More specifically, the Agency willstudy the characteristics of UST sites(number of UST sites by media type,volumes of media and debris typicallyremoved, fraction of this media anddebris that exhibits the TC, if any, etc.),current practices and requirements formanagement of these media and debris,and how contaminated media anddebris from these sites are managedunder the new subtitle I state programs.As currently envisioned, these studieswill include: (1) A survey of tankvendors, contractors, and othersknowledgeable about UST sitecharacteristics and contaminated mediaand debris management practices; (2) asurvey of current state and localprograms; and (3) a sampling programconducted in conjunc.tion with one or


Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regula.ions

more selected states. The Agency alsoplans to evaluate the impact thatsubtitle C management of petroleum-contaminated media and debris fromUSTs would have on the Agency's andstates' hazardous waste managementprograms. In addition, the inclusion ofthese media and debris in the subtitle Cmanagement system will be evaluated incomparison to the available capacity forcommercial hazardous waste treatment,storage, and disposal.

Second, the Agency will evaluatewhether and how the subtitle Crequirements can be feasiblyimplemented for UST cleanups. Thisevaluation will include an investigationof regulatory streamlining, phasedcompliance, or other administrativechanges to increase the feasibility ofimplementing UST cleanups inaccordance with subtitle Crequirements. As part of this effort andthe larger issue of the application ofsubtitle C requirements to contaminatedmedia, EPA intends to convene a publicforum to discuss the relationshipbetween subtitle C and subtitle Irequirements, the impacts of the subtitleC program on UST cleanups, and howthe subtitle C requirements can feasiblybe applied to the UST cleanups.

EPA requests data and comment fromthe public on these issues. Uponcompletion of the evaluations describedabove, EPA will determine whether toretain the temporary exemption for USTcleanups provided in this rule or toremove the exemption and make the TCfully applicable to corrective actionsunder subtitle I.

7. RCRA Section 3004(n) Air Regulations

In HSWA, Congress directed EPA to* * promulgate such regulations for

the monitoring and control of airemissions at hazardous waste treatment,storage, and disposal facilities, includingbut not limited to open tanks, surfaceimpoundments, and landfills, as may benecessary to protect human health and,the environment." This provision wasadded as section 3004(n) of RCRA. Inresponse, the Agency proposed the firstof a multi-phased set of air regulationsfor TSDFs on February 5, 1987 (53 FR3748). This first phase is intended toapply to equipment that would be usedto treat wastes that would first besubject to the Land DisposalRestrictions (LDR) standards to ensurethat the LDR treatment did not result incross-media transfer of hazardousconstituents to the air (see 111.1.2., above,for a discussion of the LDR program).This first phase is to be followed byproposals for more comprehensive airregulations for TSDFs. Once these airstandards are promulgated, they are

expected to apply to many of the wastesnewly regulated by today's rule.

The February 5, 1987 proposal wouldlimit air emissions of organics as a classfrom certain treatment units. Theproposed rule would apply to specifiedequipment that contains or is in contactwith certain hazardous wastes, whichare identified based upon their potentialto emit organics. The proposedstandards contain two major features.First, a 95% reduction in processemissions from units distilling orstripping (air or steam) organic wasteswould be required. Second, leakdetection and repair programs would berequired for certain valves, pumps,compressors, pressure relief devices,and closed-vent systems. If wastes that

.exhibit the TC also have concentrationsof organic constituents exceeding theregulatory threshold, they will besubject to this first phase of regulationfor air emissions.

j..Relationship to Other RegulatoryAuthorities

1. Comprehensive EnvironmentalResponse, Compensation, and LiabilityAct (CERCLA)

Although promulgated in fulfillment ofa RCRA mandate, today's rule mayaffect, to varying degrees, remediationsperformed under CERCLA authority.Such effects or interactions, when theyarise, will be associated with section121(d) of CERCLA, which requiresCERCLA remedial actions to complywith all applicable or relevant andappropriate requirements (ARARs) ofother federal and state laws, includingRCRA.

Several commenters questioned theapplicability of the TC to CERCLA sitesand argued that the TC would constrainthe discretion of Remedial ProjectManagers and On-Scene Coordinators..However, CERCLA section 121(d) isclear that CERCLA remediations mustcomply with. Federal and State ARARs.Accordingly, RCRA regulations,including today's TC, are incorporatedinto the CERCLA decision-making andremediation process to augment controlsalready in place under the CERCLAprogram.

In addition, a few commenters arguedthat as a result of today's rule, a greaternumber of hazardous wastedeterminations would be made duringCERCLA remediations. Consequently,"thousands of additional Superfundsites" would be created, attributable inlarge part, one commenter notes, topetroleum and petrochemical waste thatwill exceed TC levels. The Agencydisagrees with the commenters. While itis clear that CERCLA remediations must

-comply with Federal and State ARARs,the TC is not used by CERCLA todetermine whether or not to undertake aclean-up action. Rather, the TC will.apply to decisions concerning themanagement of solid wastes (e.g., soiland debris) generated during cleanupactivities.

2. Clean Water Act

a. Conflict with NPDES EffluentGuidelines and Pretreatment Standards.Many commenters argued that theregulatory levels in the proposed TCconflict with NPDES effluent guidelinesand pretreatment standards under theClean Water Act (CWA). Severalcommenters stated that in many cases,the proposed TC regulatory levels arelower than the concentrations allowedin wastewaters directly discharged tosurface waters in compliance withNPDES effluent guidelines. Commentersalso stated that many wastewaters thatare indirectly discharged to publiclyowned treatment works in compliancewith pretreatment standards will exhibitthe TC.

.Most of the commenters argued that itwould be difficult to justify labeling awastewater as "hazardous" underRCRA, but "safe" under the CWA. Onecommenter claimed that differentialtreatment of identical wastewaters isparticularly difficult to justify becauseleaks from on-site wastewatermanagement operations normallymigrate to the same bodies of Water thatreceive NPDES-permitted discharges.

EPA acknowledges the possibility thatsome wastewaters that meet NPDESeffluent guidelines or pretreatmentstandards may exhibit the TC. However,because the statutory bases for settingregulatory levels are different under theCWA ard RCRA, the treatmentstandards and effluent limitationsestablished under the CWA are notinconsistent with the TC rule. The CWArequires EPA to set effluent limitationsto control discharges of toxic pollutants.* .* which shall require applicationof the best available technologyeconomically achievable .* " and toset more stringent effluent limitationswhere necessary to meet applicablewater quality standards (see CWAsection 301(b)). RCRA, however,mandates that EPA identify wasteswhich may be a threat to human healthor the environment. The criteria for theidentification and listing of hazardouswaste requires EPA to take into account".* * toxicity, persistence, anddegradability in nature, potential foraccumulation in tissue, and other relatedfactors such as flammability,corrosiveness, and other hazardous

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characteristics" (see RCRA section3001(a)). These criteria are differentfrom those used under the CWA.

Accordingly, the two statutoryprograms have different goals. EPAbelieves that the TC regulatory levelsrepresent concentrations above which awastewater poses a potential hazard tohuman health and the environment, ifmismanaged, even if it has been treatedto some degree. Therefore, owners andoperators of wastewater treatmentfacilities that treat wastewatersexhibiting the TC will be required tocomply with all applicable regulationsunder RCRA and the CWA.

b. Permit Requirements forWastewater Treatment Facilities. Manycommenters stated that under theproposed TC, many wastewatertreatment facilities will becomehazardous waste treatment facilitiessubject to full RCRA permittingrequirements. These commenters wereconcerned that the costs to industry ofpreparing permit applications andcomplying with RCRA regulations forhazardous waste treatment facilitieswill be prohibitive. Some commentersargued that EPA has insufficientresources to process permit applicationsfrom all of the wastewater treatmentfacilities that will require permits.

Although owners and operators ofsome wastewater treatment facilitiesthat use newly-regulated surfaceimpoundments could be subject toRCRA permitting requirements, EPAbelieves that the actual number offacilities requiring permits will not btslarge. The Regulatory Impact Analysisfor this rule indicates that other optionsavailable to wastewater treatmentfacilities treating wastewatersexhibiting the TC are likely to be morecost-effective than obtaining an RCRApermit (see section VI. B for a moredetailed discussion). In particular, analternative that the Agency expects maybe attractive to many owners andoperators is the replacement of surfaceimpoundments with tanks. Retrofittingexisting surface impoundments to meetRCRA requirements for hazardouswaste management facilities will oftenbe more expensive than building tanksthat are subject to CWA requirements in

-lieu of RCRA permitting requirements.("Wastewater treatment units" areexempt from the hazardous wastemanagement standards under 40 CFR264.1(g)(6) and 265.1(c)(10). Similarly,"totally enclosed treatment facilities"are exempt under 40 CFR 264.1(g)(5) and265.1(c)(9).) Thus, there are optionsavailable to owners/operators for whomRCRA standards may be too costly.

There may be some wastewatertreatment facilities that opt to continue

using surface impoundments tomanagewastewaters exhibiting the TC, andthese facilities will enter the RCRApermitting system. However, the Agencydoes not believe that there will be sucha large number of facilities that it willoverwhelm the Agency's permittingcapabilities.

c. Sludges from Publicly OwnedTreatment Works (POTW. Thepreamble to the June 13, 1988 proposedrule requested comments on theregulation of sewage sludge underRCRA and under-the CWA. Thepreamble stated that EPA wasconsidering an exemption from RCRAregulation for sludges from publiclyowned treatment works (POTW sludges)upon the promulgation of sewage sludgemanagement standards pursuant tosection 405(d) of the CWA.

A number of commenters, includingmany municipalities, responded to thisrequest for comments.Although a fewcommenters opposed an exemption fromRCRA for POTW sludges, the.commenting municipalities supported anexemption from RCRA. Thesemunicipalities stated that sewage sludgemanagement regulations, in addition topretreatment standards, are sufficient toprotect human health and theenvironment without additionalregulation under RCRA. Commentersstated that regulating POTW sludgeunder RCRA will place a significanteconomic burden on municipalities andwill cause municipalities and EPA toface duplicative administrative costsand regulatory confusion.

EPA does not agree with commentersthat regulation of POTW sludge underRCRA will place a significant economicburden on municipalities or increase theburden of implementation. EPA's officeof Water tested 18 POTW sludgesamples using the TCLP; none of thesamples tested exhibited the TC at theproposed regulatory levels (Ref. 18).Because the final TC regulatory levelsare higher than the proposed regulatorylevels, the Agency believes that few, ifany, POTW sludges will exhibit the TC.Thus, most POTW sludges will not beclassified as hazardous waste underRCRA.

Although EPA does not believe it isnecessary to exempt POTW.sludgesfrom RCRA'at this time, the Agency mayreconsider this decision after thesewage sludge management regulationsare promulgated. In the unlikely eventthat a particular POTW sludge doesexhibit the TC, the municipality may usethe pretreatment program under theCWA to eliminate the iridirectdischarges of the pollutants that arecausing the sludge to exhibit the TC.

3. Safe Drinking Water Act

Several commenters noted that theproposed regulatory level for chloroformis lower than the primary drinking waterstandard for trihalomethanes (a class oforganic chemicals that includeschloroform] established under the SafeDrinking Water Act (SDWA). Most ofthese commenters consequentlydeclared that the regulatory level hadbeen set too low, and they argued that itwould be unreasonable to regulateordinary drinking water as a hazardouswaste. Some commenters asserted thatan industrial facility taking water from apublic water supplier-(a facilitysupplying drinking water in compliancewith the SDWA rules) could find that itsnoncontact cooling water becomes ahazardous waste after it is passedthrough the plant and is disposed.

In today's final rule, the regulatorylevel for chloroform has been raisedfrom that proposed in the June 13. 1986,notice of proposed rulemaking. Thechange is because of two modificationsto the data originally used to set theregulatory level: first, the chronictoxicity reference level for chloroform isroughly 12 times higher than whenoriginally proposed (see 53 FR 18024)and, second, due to the changes in themodel, the DAF is about 7 times higherthan the one originally proposed.Together, these two changes result in aregulatory level that is higher than boththe original regulatory level and theSDWA standard for trihalomethanes.Non-contact cooling water or otherwastewaters derived from public watersupplies complying with the SDWA thusshould not exhibit the TC for chloroformunless these wastewaters arecontaminated by other sources.

4. Federal Insecticide, Fungicide, andRodenticide Act (FIFRA)

a. Pesticide Wastes. The FederalInsecticide, Fungicide, and RodenticideAct [FIFRA) authorizes EPA regulationof pesticide sale, distribution, use, anddisposal. Since RCRA regulations coversolid wastes which include pesticideproduct wastes, these wastes may beregulated under both FIFRA and RCRA.

Until recently, pesticide disposalunder FIFRA was primarily controlledby mandating that product labelinginclude instructions for the properdisposal of the pesticide and itscontainer. Recent amendments toFIFRA, effective October 25, 1988,authorize the Administrator to imposeadditional requirements relating tostorage, transportation, and disposal ofcertain pesticides. For example, EPAunder FIFRA may issue requirements



and procedures for the storage,transportation, and disposal ofsuspended or cancelled pesticides andof rinsates or containers associated withthe pesticides. Also, EPA may requirethat applicants for registration of apesticide submit information regardingmethods for safe storage and disposal ofthe pesticide, and that applicants forregistration provide evidence ofsufficient financial resources to providefor disposal in the event of suspensionor cancellation.

A number of pesticide-related wastesare listed as hazardous under 40 CFRpart 261. The listings include fourgroups: The first, at § 261.31, includescertain discarded unused pesticideformulations containing tri-, tetra-, andpentachlorophenols (F027) or certaincompounds derived from thechlorophenols; these are listed as acutehazardous waste. This listing includesapproximately 20 phenoxy pesticidesand their salts and esters. Today's rulewill add the constituent 2,4,6-trichlorophenol, which is used as anactive ingredient in'pesticide products,to the TC list. Because productscontaining this constituent areseparately listed under F027, thepromulgation of specific toxicity limitswill not affect their regulation underRCRA (i.e., they will continue to beregulated as acute hazardous wastes atall concentrations, both above andbelow the TC level).

The second group, at § 262.32. consistsof "K" wastes from the production ofspecific pesticides, such as wastewatertreatment sludges from the production ofthe pesticide chlordane (K032); these arelisted as toxic wastes. Again, however,because these wastes are listed, theywill not be affected by the regulatorylevels of the TC, but will continue to besubject to regulation regardless ofconcentration levels.

The third grouping, at § 261.33 (e) and(f), consists of "P" and "U" wastes.Section 261.33 lists certain commercialchemical products as hazardous whendiscarded or intended for discard.Approximately 50 pesticide activeingredients are listed as acutehazardous wastes under § 261.33(e),while 83 pesticide active ingredients arelisted under § 261.33(f) as toxichazardous wastes. Pesticide productscontaining these chemicals as soleactive ingredients or the pure ortechnical grade of these chemicals areregulated under both RCRA and FIFRAwhen they become wastes. Generally,pruducts containing these ingredients asone of multiple active ingredients arenot regulated (at this time) as hazardouswastes under subtitle C of RCRA unless

they meet one of the characteristics;their disposal is still subject to anyapplicable FIFRA and RCRA subtitle Drequirements. For the majority of the 133listed pesticides, today's rule will notchange their status under RCRA; wastepesticides that are either pure, technicalgrade, or sole active ingredient productswill continue to be subject to regulationas hazardous at all concentrations underRCRA subtitle C. Wastes from multipleactive ingredient products that do notexhibit a characteristic will still beregulated under any applicable FIFRAand RCRA subtitle D requirements.

Six pesticide wastes that are currentlyregulated on a concentration basisunder the existing EPTC at § 261.24,form the fourth group. These sixpesticides (endrin, lindane,methoxychlor, toxaphene, 2,4-D, andsilvex) will be retained in the new rulewith their current concentration limits,which are based on a DAF of 100. Thesignificant difference between thelistings and the TC is that, whilemultiple active ingredient products arenot covered by the listings, they arecovered under the characteristic. Thus,increasing the number of pesticidalconstituefits encompassed by the TC(whether or not they are also listed),brings more multiple active ingredientformulations into the subtitle C system.Consequently, today's rule is expandingregulation of pesticide wastes underRCRA.

Although EPA is adding pesticides tothe TC list of constituents, today's rulewill not have a significant effect onmany pesticide users who generatewastes. RCRA regulations containspecial requirements that affect theextent to which pesticide users willbecome subject to additional RCRAregulation:

* Household pesticide wastes are,like other household wastes, exemptfrom RCRA.

* Farmers who triple rinse theircontainers and dispose of the rinsate ontheir own farm in a manner consistentwith 40 CFR 262.51 and labelinstructions are exempt from RCRArequirements.

• Other small quantity generatorsunder § 261.5 need comply only withreduced requirements. Many pesticideusers are small quantity generators.

* Under § 261.7, properly emptiedcontainers may be exempted fromfurther RCRA requirements. Thus, manypesticide containers may not be subjectto regulation as hazardous wastes.

As a result, -the principal effects oftoday's final rule will be felt bycommercial applicators, such as aerialapplicators and pest control operators,

who are not eligible for the specialrequirements applicable to farmers andwho may use sufficiently large volumesof pesticides that they exceed the smallquantity generator limitations.. If theyuse large quantities of multiple activeingredient pesticide products that havenot previously been regulated, suchcommercial applicators may be newlysubject to the RCRA hazardous wastemanagement requirements.

b. Treated Wood Wastes. The Agencyis promulgating TC regulatory levels forcertain chemicals-for example, cresolsand pentachlorophenol-that arecommonly used as wood preservatives.In its review of wood preservativechemicals under FIFRA, EPA concludedthat these wood preservatives maycontinue to be used under certaincircumstances, and the Agency decidedto allow disposal of treated wood bymeans of ordinary trash collection,burial, or incineration (49 FR 28666, July13, 1984, and 51 FR 1334, January 10,1986). However, the mandates of FIFRAand RCRA are different. EPA haspreviously stated that even if it weredetermined that certain ground uses oftreated wood did not pose unreaponablerisks, wood wastes might still beregulated under RCRA subtitle C (45 FR78531, November 25, 1980). UnderFIFRA, the Agency may determine thatthe economic benefits of continued useof a pesticide outweigh any potentialrisks posed by the pesticide. This doesnot mean, however, that materialstreated with pesticides should not bemanaged in a controlled manner underRCRA'at the end of their useful lives, toensure that long-term risks areminimized.

Some treated wood that is hazardoussolely because it fails the EP toxicitytest for arsenic which is not a hazardouswaste for any other reason or reasons isexempt from regulation as hazardous (40CFR 261.4[b)(9)). The exemption islimited to wood wastes generated bypersons who use wood products for theirintended end use. Several commentersclaimed that large quantities of treatedwood wastes will be newly regulated ashazardous under the TC, and theyargued that this result is inconsistentwith other EPA policies and regulations.Most of these commentersrecommended that EPA expand theexisting exemption for arsenic-treatedwood waste to encompass all treatedwood that exhibits the TC.

EPA has decided not to expand theexisting exemption for arsenic-treatedwood. If t wood waste does exhibit theTC for a constituent other than arsenic,or if the waste is hazardous waste forany other reasons or reasons, the

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Agency believes that the waste shouldbe regulated as hazardous, in order toprotect human health and theenvironment. The arsenic-treated woodexemption is not being revoked'at thistime, but it may be reevaluated in thefuture.

5. Food, Drug, and Cosmetic Act (FDCA)a. Food Wastes. Several commenters

noted that allowable levels set by theFood and Drug Administration (FDA)under the Food, Drug, and CosmeticsAct (FDCA) are, in some cases, higherthan the proposed TC regulatory levelsfor the same chemicals. Most of thesecommenters then asserted that if it issafe to consume substances containingpesticides or additives, it must also besafe to place such substances inmunicipal landfills. Some commentersexpressed concern that food wastes thatcomply with FDCA pesticide toleranceor action levels may nevertheless haveto be handled as hazardous wastes as aresult of the TC. One food processingindustry trade association requestedthat the final TC rule state that anywaste from food already in compliancewith a tolerance or action level set byEPA or FDA is nonhazardous.

The Agency acknowledges that forcertain chemicals in waste, it proposedTC regulatory levels lower than FDCAtolerances or action levels in food.However, it is inappropriate to make adirect comparison of these two sets oflevels. FDCA levels are set forconcentrations in food products, whileTC levels apply to concentrations in theleachate from waste materials. Becausenot all toxic constituents leach from thewaste, levels in the leachate are lowerthan in the waste material itself.Accordingly, for a food waste to behazardous, the waste would have tohave constituent concentrations higherthan the TC levels. The Agency isunaware of any food-related wastes thatwill be regulated as hazardous under theTC rule. (In addition, unlike the FDCA,RCRA does not allow consideration ofeconomic factors in establishingregulatory levels of concern.)

If any food waste does exhibit the TC,it may be subject to lesser requirementsas household waste (40 CFR 261.4(b)(1))or under the small quantity generatorprovisions (40 CFR 261.5). For non-household food wastes that fail the TC(i.e., leachate from the waste containscontaminants in levels equal to or abovethe regulatory levels promulgated intoday's rule) and that are generated inlarge quantities, it is appropriate thatthey be managed in a controlled mannerto protect human health and theenvironment. Because EPA sees noconflirt between the TC rule and

tolerance or action levels under FDCA,this rule contains no exemption forwastes that meet the FDCA standards.

b. Pharmaceutical and CosmeticWastes. Several commenters, arguingthat the proposed TC levels were toolow, pointed out that the proposedregulatory levels are lower than FDCA-allowed levels for the same chemicals indrugs or cosmetics.

Although the proposed TC regulatorylevels for certain chemicals were lowerthan the FDCA levels for the same.chemicals in drug and cosmeticproducts, the levels are higher in thefinal rule. Moreover, it is clear thatdifferent factors must be taken intoaccount when regulating theseconstituents in drugs and cosmeticsrather than in solid wastes, as confirmedby different statutory mandates. Theconstituents in drugs and cosmeticsproducts, often used in very small.

.quantities, serve a useful function andmay be therapeutic in certain quantitiesand under proper circumstances.However, this does not mean that thesesame constituents should not becontrolled where found at TC levels inwaste materials.

Of course, drug and cosmetic wastesgenerated in households are not subjectto subtitle C regulation (40 CFR261.4(b)(1)) nor are wastes generated bysmall quantity generators (less than 100kg/mo of non-acute hazardous waste-see 40 CFR 261.5). However, drug andcosmetic products when discarded maypresent risks to human health and theenvironment if disposed in largevolumes. Thus, EPA maintains thatregulation of large quantities of drug orcosmetic wastes exhibiting the.TC is

-appropriate and not in conflict with theexisting FDCA program.

6. Used Oil Recycling Act

The Used Oil Recycling Act of 1980(UORA), which amended RCRA, wasintended to increase safe recycling andreuse of used oil. It established that it isin the national interest to recycle usedoil in a manner that both protects publichealth and the environment andconserves energy and materials. TheUORA has been incorporated in section3014 of RCRA.

Section 3014 of RCRA, as amended byHSWA, requires EPA to make adetermination of whether to list oridentify used oil as a hazardous waste(see RCRA section 3014(b)). In responseto this statutory directive, EPA proposedto list most types of used oil, includingrecycled used oil, as a hazardous wasteon November 29, 1985 (see 50 FR 49258).EPA subsequently decided in November,1986 not to list used oil because theAgency believed that the listing would

discourage recycling of used oil andcould result in an increase in the amountof used oil that is disposed of or illegallydumped. The Agency decided tocontinue to study whether used oil thatis disposed should be listed as ahazardous waste under RCRA orregulated under different statutes (see 5:1FR 41900 (November 19, 1986)). EPA'sdecision to withdraw the proposedlisting of used dils was invalidated bythe D.C. Circuit Court of Appeals in1988. The Agency was directed by theCourt to reconsider the listing of used oilas a hazardous waste based on thetechnical criteria contained in RCRAsection 3001.

Some commenters claimed that usedoil would be brought into the subtitle Csystem under the TC proposal. Theystated that used oil is likely to fail theTC test for both aromatic hydrocarbons(e.g., benzene) and chlorinated solvents(e.g., trichloroethylene andtetrachloroethylene). The commentersargued that regulating used oil as ahazardous waste would be inconsistentwith the intent of the UORA, as well aswith current Agency policies regardingused oil.

Under today's rule, used oil will beregulated as a hazardous waste only: (1)If it exhibits one or more of thehazardous waste characteristics definedin subpart C of 40 CFR part 261(including the TC as finalized today)and (2) if it is disposed of (rather thatrecycled). On the other hand, used oilthat exhibits one or more of thehazardous waste characteristics and isrecycled is exempt from regulation (see40 CFR 261.6(a)(3)(iii)) except asprovided in subpart E of 40 CFR part266. In addition, RCRA prohibits the useof used oil as a dust suppressant or forroad treatment if it is contaminated withdioxin or mixed with a hazardouswaste. Thus, used oil that exhibits oneor more of the characteristics (except forignitability) cannot be used as a dustsuppressant. In particular, theregulations have the following effect:

e Solid waste that is hazardous wastebecause it fails a characteristic and thatis recycled (except by burning or use asa dust suppressant) is exempt fromregulation.

• Characteristically hazardous usedoil that is disposed of (or incineratedwithout recovery of energy value) issubject to full RCRA subtitle Cregulation.

- Characteristically hazardous usedoil that is being burned for energyrecovery is subject to subpart E of part266-i.e., off-specification used oil issubject to certain administrativerequirements, while specification used



oil is subject only to the analysis and-recordkeeping requirements of 40 CFR266.43(b) (1) and (6).

* Characteristically hazardous used,oil is prohibited from being used as adust suppressant, unless it is hazardoussolely for exhibiting the ignitabilitycharacteristic (see 40 CFR 266.23(b)).

0 Characteristically hazardous usedoil that is recycled in any manner otherthan being burned for energy recovery(e.g., by being rerefined) is exempt fromsubtitle C regulation.Therefore, today's rule will not affectthe regulatory status of most recycledused oil. In fact, today's rule shouldencourage the recycling of used oil, andnot discourage its recycling as suggestedby some commenters. It should also benoted that some percentage of used oilalready is defined as hazardous (i.e.,exhibits one or more of the hazardouswaste characteristics and is disposed).Consequently, the amount of used oilthat is affected by this rule and is eitherdisposed of or recycled by being burnedfor energy recovery or used as a dustsuppressant will be even less.

The Agency is currently determininghow best to deal with used oil listingand management issues. Section 3014 ofRCRA also requires EPA to promulgatemanagement standards for used oil thatis recycled. Standards for controllingused oil which is recycled wereproposed on November 29, 1985 (50 FR49212), but have not been finalized. TheAgency will be addressing these issuesas well as addressing the listingdetermination in the near future.

7. Toxic Substances Control Act (TSCA)EPA has decided to exempt from the

application of this rule certainpolychlorinated biphenyl [PCB) wastesthat are regulated under the ToxicSubstances Control Act (TSCA) andwould be identified as hazardousbecause of today's rule. Specifically,PCB-containing dielectric fluidsremoved from electrical transformers,capacitors, and associated PCB-contaminated electrical equipment mayexhibit the TC, and thus becomehazardous wastes when disposed, notbecause they contain PCBs (which arenot among the constituents regulatedunder the TC) but because they maycontain other TC constituents, such aschlorinated benzenes. The Agency hasdecided to exempt such wastes from thesubtitle C management standardsbecause new regulation of these wastesunder RCRA may be disruptive to themandatory phaseout of PCBs in certainelectrical transformers and capacitors.In addition, the Agency believes that theregulation of these wastes under TSCAis adequate to protect human health and

the environment. However, theexemption applies only to thosedielectric fluids (as described above)that are fully regulated under TSCA.Other PCB-containing wastes that arehazardous (i.e., listed or exhibit ahazardous waste characteristicincluding the existing EPTC wastes-waste codes D004 through D017) aresubject to all applicable subtitle Cstandards. Furthermore, these non-TChazardous wastes that are (1) liquidscontaining PCBs at concentrationgreater than 50 ppm, or (2) solidscontaining PCBs listed in Appendix III ofpart 268 at concentrations greater than1000 mg/Kg, are prohibited from landdisposal under 40 CFR part 268.

The disposal and storage of PCBwastes is regulated under TSCA section6(e)(1) authority rather than undersubtitle C of RCRA. Since the enactmentof TSCA, the manufacture, processing,and distribution in commerce of PCBs(without an exemption) has beenbanned and the use of PCB withoutauthorization has been banned. Inaddition, EPA has developedcomprehensive PCB disposal regulationsunder TSCA. This regulatory frameworkincludes specific disposal requirementsfor defined classes of PCB wastes,specific marking requirements for PCBitems, facility recordkeepingrequirements, approval requirements fordisposers, and a proposed notificationand manifesting system modeled on thesubtitle C "cradle to grave" trackingsystem.

One commenter stated that utilitytransformer dielectric fluids are likely toexhibit the revised TC and urged theAgency.to exempt PCB-containing utilitytransformer dielectric fluids from therule. The commenter noted that theregulation of PCBs is unique because themanufacture of PCBs (without anexemption) has been banned. Thus, thecritical regulatory concern with respectto these PCB wastes is the need toexpedite safe disposal of the chemical.The commenter stressed that if PCBwastes were to be regulated now underRCRA as well as under TSCA, seriouslegal, practical and administrativecomplications could result.

The Agency agrees with thecommenter. The most significantpotential negative impact of dualregulation of these wastes under bothRCRA subtitle C and TSCA results fromthe unique scope and timing orPCBdisposal. The Agency estimates thatapproximately 312 million pounds ofPCBs are dispersed among nearly 30million discrete units of electricalequipment. The TSCA regulationsrequire the phaseout of certain PCB-containing electrical transformers, and

EPA expects that the TSCA mandatoryphaseout requirements and restrictionswill render the next three years a peakperiod for PCB disposal. Under theauthority of the TSCA mandatoryphaseout, by October 1, 1990, owners ofsecondary network higher voltagetransformers located in or nearcommercial buildings are required toeither remove or reclassify thesetransformers. (Reclassificationnecessitates draining of all PCB fluidsfrom the unit, and replacing them withnon-PCB fluids or low concentrationPCB fluids, and keeping the transformerin full service, under loaded conditions,for a minimum of three months.) Inaddition, the phaseout restrictions affectlower secondary voltage network unitsof PCB-containing electricaltransformers located in or nearcommercial buildings; by October 1,1993, such transformers must either beremoved or be reclassified, or analternative option for lower voltageunits allows for providing enhancedelectrical protection on such units byOctober 1, 1990. Radial PCB-containingelectrical transformers must either haveenhanced electrical protection or beremoved.

The TSCA program, with which theregulated community is familiar, isspecifically tailored to deal with theproblem of widely dispersed wastegeneration and the timely disposal of achemical that is no longer commerciallyproduced. The confusion that couldresult from the addition of requirementsunder a separate regulatory disposalsystem, and the RCRA disincentives towaste production, would causesignificant disruption to the expeditiousdisposal of large quantities of these PCBwastes if these wastes were to becomesubject to the RCRA hazardous wasteregulations.

In addition, the Agency believes thatthe existing system for PCB disposal,including the existing TSCA disposalregulations and recent additions to theprogram (e.g., the proposed notificationand manifesting rule, published at 53 FR37436), are adequate to protect humanhealth and the environment with respectto the disposal of these wastes. Thus,further regulation under RCRA for PCB-containing dielectric fluids andassociated PCB-contaminated electricalequipment does not appear to benecessary at this time. The Agency willalso evaluate the integration of theTSCA PCB regulations with the RCRAhazardous waste regulations for otherPCB-containing wastes which areidentified or listed as hazardous.

11841



K. Implementation Issues

EPA received many commentsconcerning implementation of the TCrule. The comments addressed issuesincluding the schedule for companiesand municipalities to come intocompliance with subtitle Crequirements, exemptions andapplicability, implications for permitmodifications, and administrativerequirements. Major comments onimplementation are summarized andaddressed below. Section V of thispreamble further discusses how theAgency will implement today's rule.

1. Notification

In the June 13, 1986 Federal Registernotice, EPA proposed to waive theRCRA section 3010 notificationrequirement for persons who manage TCwastes and have already: (1) Notifiedthe Agency that they manage otherhazardous wastes and (2) received anEPA identification number. Virtually allcommenters Wvho addressed thenotification requirement supportedEPA's proposal. However, one stateagency opposed the proposal, on thegrounds that a waiver would hinderefforts to develop a more accurate andcomplete understanding of hazaidouswaste management practices within theUnited States.

EPA has decided, as proposed, towaive the notification requirement forTC waste handlers that have alreadynotified the Agency that they managehazardous wastes and have received anEPA identification number. The Agencybelieves that, given the vast scope of theTC rule, a notification requirement forpersons already identified within thehazardous waste management universewould present an administrative burdenwithout providing any significantbenefits to human health and theenvironment.

2. Effective Date

Several commenters claimed that the6-month effective date of the TC rulewould not provide them with sufficienttime to come into compliance with thefull array of hazardous wasteregulations. Some commenters arguedthat it would be impossible forgenerators of TC wastes to test theirwastes, obtain EPA identificationnumbers, arrange for transport and off-site management of their wastes, modifytheir short-term storage (i.e.,accumulation) practices, and institutethe necessary recordkeeping andreporting procedures within a 6-monthtime frame. The commenters stated thatthe time constraints are especiallyunreasonable in light of the shortages of

laboratory and TSDF capacity that canbe expected to result from the TCrevisions. Other commenters claimedthat TSDFs will require more than.6months to come into compliance withthe interim status standards of 40 CFRpart 265 (e.g., personnel training,contingency planning, and financialresponsibility).

EPA appreciates the concerns of thecommenters, and the Agency is awarethat all of the commenters addressingthe effective date for the TC ruleencouraged EPA to adopt a delayedeffective date for most, if not all,requirements. However, RCRA section3010(b) requires that hazardous wasteregulations become effective 6 monthsafter the date of promulgation unlessEPA has good cause to establish anearlier effective date. Thus, the effectivedate for the final TC rule will be 6months from the date of promulgation.

However, EPA is promulgatingdifferent compliance dates for twodifferent categories of waste generators:(1) All generators of more than 100 andless than 1,000 kg/month of hazardouswaste (small-quantity generators) mustcome into compliance with subtitle Crequirements for management of theirTC waste within one year of today; and(2) all generators of 1,000 kg/month ormore of hazardous waste are required tocomply with all subtitle C requirementsfor TC wastes within six months oftoday, on the effective date of the rule.

All generators of over 1,000 kg/monthof hazardous waste are required tocomply with all applicable RCRAregulations for their TC wastes on theeffective date of this rule. (The generatorquantity refers to all of a generator'shazardous waste, not just newlyhazardous TC waste.) The Agencyrecognizes that this compliance categorywill include two groups of generators:current hazardous waste generators,including small quantity hazardouswaste generators who will be generatingadditional hazardous wastes andgenerators of large quantities of solidwastes who will be regulated ashazardous waste generators for the firsttime. EPA believes that both of thesegroups of generators shouldpredominantly be large businesses andeither be familiar with the wastemanagement regulations or be in aposition to come into compliance withthe requirements within the six monthperiod. These persons should have beenaware of the Agency's statutorycommitment and have had ample noticeof the impending TC rule through theproposed rule and supplemental notices.

On the other hand, the Agency isallowing an additional six months from

the effective date (i.e., one year fromtoday) for generators of greater than 100but less than 1,000 kg/month ofhazardous waste (small quantitygenerators) to comply with allapplicable subtitle C regulations. (Aswith the over 1,000 kg/month category,this quantity refers to the total quantityof a generator's hazardous waste, notjust newly hazardous TC waste.) TheTC has the potential to affect anextremely large number of handlers thatnever before have been subject to thehazardous" waste regulations; many ofthese firms are small businesses.Handlers that will assume smallquantity generator status as a result ofthe TC rule are most likely not regulatedunder subtitle C at the present time.Thus, these handlers are less likely to befamiliar with the waste managementregulations, or because of their smallbusiness status, will need more than sixmonths to come into compliance withthe regulations.

As already indicated, these handlersare likely to be small entities and maybe unaware that their practices, whichwere not regulated in the past, will nowbe regulated as a result of today's rule.The Agency recognizes that these newhandlers of small quantities of TCwastes (over 100 but less than 1,000 kg/month) may have to test their wastes,obtain EPA identification numbers,arrange for transport and off-sitemanagement of.their wastes, modifytheir short-term storage (i.e.,accumulation) practices, and institutethe necessary recordkeeping andreporting procedures. As recognized bythe Agency in establishing specialrequirements for small quantitygenerators, the burden of initialcompliance may fall relatively harder onthese generators (see 51 FR 10146,March 24, 1986). Thus, to lessen theburden on the handlers of smallquantities of TC wastes, the Agency hasdeveloped an outreach program targetedfor the small quantity generators whichwill inform new generators of thereqpired steps necessary to enter thehazardous waste management system.Effective program outreach, however,will take more than 6 months.

In amending RCRA in 1984, Congress,in requiring EPA to promulgateregulations for small quantitygenerators, indicated that the Agencyshould consider the impacts on smallbusinesses, while still providingprotection to human health and theenvironment. While this rule is notpromulgated pursuant to this provision,we believe the intent of.Congress is forthe Agency (in promulgating any rulesubstantially affecting small quantity



generators) to consider such impactsand to provide procedural adjustmentswhere appropriate. EPA believes thatextending the compliance date for thisgroup of generators will allow theAgency time to provide necessaryassistance and outreach to thesegenerators and will allow sufficient timefor small quantity generators to complywith the full range of applicable subtitleC requirements. Finally, by delaying theeffective date of the TC for smallquantity generators, the Agency will beable to concentrate its initialimplementation efforts on large quantitygenerators, who will generate the vastmajority of waste brought into theRCRA subtitle C system under this rule.Thus, because the delayed compliancedate for small quantity generatorsenables the Agency to focus its attentionon the waste generators expected toproduce the largest volumes of waste, itmaximizes protection of human healthand the environment.

In summary, the Agency believes thatallowing an additional six months forsmall quantity generators to come intofull compliance with the TC will servetwo purposes. First, it will allow theAgency time to educate small quantity'generators on the RCRA rules, while atthe same time, allowing the Agency tofocus immediate implementation effortson large generators of hazardous waste.Second, it will provide the necessarytime for small quantity generators tocomply with subtitle C requirements asa result of the TC.

3. Permitting

Several commenters expressedconcern that they would not be able tosubmit required permit modificationsbefore the effective date of the rule.Some commenters also expressedconcern that the TC revisions could

place a significant burden on the systemfor permitting hazardous wastetreatment, storage, and disposalfacilities.

The commenters recommended anumber of different mechanisms forreducing the prospective burdens on thepermitting system, such as (1) Allowingpermitted facilities to operate underinterim status with respect to newlyregulated wastes; (2) handling requestsfrom permitted facilities to manage TCwastes as minor permit modifications,rather than as major permitmodifications (especially in the case offacilities that are already permitted tomanage listed wastes containing TCconstituents); (3) requiring permittedfacilities to apply for major permitmodifications by the effective date ofthe TC rule, but not requiring them toactually obtain the modification until alater date; or (4) delaying the effectivedate of the final rule.

EPA has promulgated amendments tothe procedures for permit modificationsfor treatment, storage, and disposalfacilities on September 28, 1988 (53 FR37934). These changes to the regulationsshould generally allay the concernsexpressed by the commenters. Althoughthe new permit modifications rule willnot automatically be effective inauthorized states, EPA expects thatmany authorized states will adopt theprovisions and EPA plans to use thenew permit modification procedures toimplement the TC. The new permitmodification procedures are furtherexplained in section V.

IV. Regulatory Levels

The regulatory levels established intoday's rule are based on twoelements-the toxicity of eachconstituent and the expected fate of theconstituent when released into the

environment. The latter element isexpressed as a dilution/attenuationfactor (DAF), which, when multiplied bythe toxicity value, results in theregulatory level. It is this level that,when compared to the results of theTCLP, defines a waste as hazardous. Ifthe waste leachate generated throughthe TCLP contains constituents equal toor above the regulatory levels in today'srule, the waste is a hazardous waste.

This section summarizes the Agency'sbasis for selecting the final list ofconstituents and the regulatory levelsthat are being promulgated in today'srule.

A. List of Constituents

1. Proposed List

The Agency initially proposedregulatory levels for 38 new organicconstituents, proposed to modify theregulatory levels for the six organicconstituents that are regulated under theexisting EPTC, and proposed to retainthe existing levels for the eight inorganicconstituents regulated in the existingEPTC (see Table IV-1).

2. Constituents for Which FinalRegulatory Levels Are Not Now BeingPromulgated

The model used to predict DAFs fortoday's rule accounts for hydrolysis,which may occur during the transport ofa constituent through the environment. Ifa constituent hydrolyzes duringtransport, its concentration willdecrease more rapidly than it would if itwere influenced by dispersion alone.Therefore, the DAF for a constituent thathydrolyzes during transport will behigher than that for a constituent thatdoes not hydrolyze. However, theproducts that are formed because ofhydrolysis of the constituent also maybe toxic.

TABLE IV-1.-TC CONSTITUENTS AND REGULATORY LEVELS PROPOSED JUNE 13, 1986

Constituents

D016 .................................................................................................... IAcrylonitrile .............. ............................................................................................UU4 ................................................................................................... Arsenk. ................................................................................................................

D019 .................D020 ...................D006 ..................I-~o0022...................................................... .........................................0023 ............................................................................................

D024 .......................... .................................................................D025 .................... ........................................................................D007 .............................................................................................D026 .....................................................................................................

Barium ............... . ................. . .......... . . . . . . . . . .Benzene ...............................................................................................................Bis(2-chloroethyl) ether .......................................................................................Cadm ium ..............................................................................................................Carbon disulfide ......................................................................... .......Carbon tetrachloride ...........................................................................................Chlordane ............................................................................................................Chlorobenzene ................................................................................................Chloroform ...........................................................................................................Chrom ium ............................................................................................................

m-Cresol .............................................................................................................

028 ........................................ Cresol....... .. .............................................................................n . 4. .......................................................................................................

1,2-Dichlorobenzene ........................................... ..........................................1,4-Dichlorobenzene ........................... .....................................1,2-Dichloroethane .............................................................................................

CASNO 2

107-13-17440-38-27440-39-3

71-43-2111-44-4

7440-43-975-15-058-23-557-74-9

108-90-767-66-3

1333-82-095-46-7

106-39-4106-44-594-75-796-50-1

106-46-7107-08-2

Regulatorylevel (mg/L)

5.05.0

100.00.070.051.0

14.40.070.031.40.075.0

1C.010.010.01.44.3

10.80.40

HWNO I

v v....................................................................................................0029 ....................................................................................................D030 ....................................................................................................D031 .... ..................................... ..........................................

11843

................................................................................ ............................................................................

L J/I .......................................................................................

IA ....



TABLE IV-1.-TC CONSTITUENTS AND REGULATORY LEVELS PROPOSED JUNE 13, 1986--Continued

HWNO I Constituents CASNO 2 Regulatory

1,1-Dichloroethylene...= ...................................... : ....................D033 ..................................................................................................... i Q,4-UinltrlUvilti .....................................................................D012 ................................................................................................... Endrin ........................D034 .................................................................................................... Heptachlor (and its ID035 .............. ; ...................................... .............................................. Hexachlorobenzene.D036 ................................................................................................... HexachlorobutadienD037 .................................................................................................... HexachloroethaneD038 .................................................................................................... Isobutanol .................D008................................................................................................... Lead ................D013 .................................................................................................... Lindane ..............D009 .................................................................................................... M ercury .....................D014 ................................................................................................... M ethoxychlor ............D039 .................................................................................................... M ethylene chloride..D040 ........................................................................... ............... M ethyl ethyl ketone.D041 .................................................................................................... Nitrobenzene ............D042 ...................................................................................... PentachlorophenoL..0043 .. ....................................... ....................................... Phendl ..............D044 ....................................................................................................D010 ...................................................................................................D0 1 ....................................................................................................D045 ..................................................................................................D046 ....................................................................................................D047 ....................................................................................................D048 ....................................................................................................D049 ....................................................................................................D015 ....................................................................................................D050 ....................................................................................................D051 ...................................................................................................D052 ...................................................................................................D053 ..................................................................................................D054 ..............................................................................................D0 17 ........................................................................................D066 ........................................................................... .....................

'EPA Hazardous Waste Code Number.'Chemical Abstracts Service number.

nyoruxluue .................................................

Pyridine ...............................................................................................................Selenium ..............................................................................................................Silver ...................................................................................................................1,1,2,2-Tetrachloroethane ................................................................................1,1 ,2,2-Tetrachloroethane ................................................................................Tetrachloroethylene ...........................................................................................2,3,4,6-Tetrachlorophenol .................................................................................Toluene ...............................................................................................................Toxaphene ......................................................................... ; ................................1.1 ,1-Trichloroethane ..................................................................................1,1 ,2-Trichloroethane ........................................................................................Trichloroethylene ...............................................................................................2,4.5-Trichlorophenol .......................................................................................2.4,6-Thchlorophenol ........................................................................................2,4,5-TP (Silvex) ....................................... ...................................................Vinyl chloride ......................................................................................................

D032. 75-35-4121-14-2

72-20-876-44-2

118-74-187-68-367-72-178-83-1

7439-92-158-89-9

7439-97-672-43-575-09-278-93-396-95-387-86-5

106-95-2110-86-1

7782-49-27440-22-4

630-20-679-34-5

127-18-458-90-2

o 106-8-38001-35-2

71-55-679-00-579-01-695-95-488-06-293-76-575-01-4

As explained in section III.E.2.a.vii,the Agency does not have sufficient datato address the formation and toxicity ofhydrolysis products. Therefore, intoday's rule, the Agency is notestablishing regulatory levels for thosenew organic constituents that areexpected to appreciably hydrolyze andthereby form potentially toxic by-products. Rather, the Agency expects toaddress these constituents in a futureFederal Register notice.

Three of the organic constituentscurrently regulated by the EPTC mayhydrolyze to a significant extent.However, due to uncertaintiesassociated with this mechanism, theAgency believes that it would not beprudent to remove these constituentsfrom regulation on a temporary basis(i.e., until their hydrolysis products canbe assessed). Therefore, theseconstituents (endrin, methoxychlor, andtoxaphene) will continue to be regulatedat the existing EPTC levels in theinterim.

Also, as explained in section III.E.2.a,the Agency has concluded that thesteady-state assumption used in theground water transport model may notbe appropriate for all constituents. Theconstituents for which a steady-statesolution may not be appropriate are

being deferred from the list of proposedconstituents. EPA will promulgate orrepropose (as warranted] regulatorylevels for these constituents in a futureFederal Register notice.

3. Final List of Constituents

a. Organic Constituents. The organicconstituents for which the Agency istoday establishing regulatory levels (i.e.,those that are on the current EP list, andthose that do not appreciably hydrolyzeand for which a steady-state assumptionis appropriate) are presented in TableIV-2.

TABLE IV-2.-ORGANIC CONSTITUENTS

EPA HWnumber I

D018. ; ...........D0 19 ............D020 .................D021 ..................D022 ..................D023 ..................D024 ..................D025 ..................0016 ..................0027 ..................D028 ..................D029 ..................D030 ..................D012 ..................

Contaminant nCAS

Benzene .....................Carbon tetrachloride...Chlordane ....................Chlorobenzene ...........Chloroform ...................o-Cresol ........................m-Cresol .......................P-Cresol ........................2,4-D .............................1,4-Dichlorobenzene..1,2-Dichloroethane.1, 1 -Dichloroethylene...2,4-Dinitrotoluene.Endrin ........................

71-43-256-23-557-74-9

106-90-767-66-395-46-7

106-39-4106-44-5

94-75-7106-46-7107-06-2

75-35-4121-14-2

72-20-8

TABLE IV-2.-ORGANIC CONSTITUENTS-

Continued

EPA HW Contaminant CASnumber C inumber'

D031 .................. Heptachlor (and its 76-44-2hydroxide).

D032 .................. Hexachlorobenzene 118-74-1D033 .................. Hexachloro-1,3- 87-68-3

butadiene.D034 .................. Hexachloroethane 67-72-1D013 .................. .indane ........................ 58-89-9D014 .................. Methoxychlor.............. 72-43-5D035 .................. Methyl ethyl ketone .... 78-93-3D036 ................ Nitrobenzene ............... 96-95-3D037 ................ * Pentachlorophenol ...... 87-86-5D038 .................. Pyridine ........................ 110-86-1D039 ........ Tetrachloroethylene 127-18-4D015 .................. Toxaphene ................... 8001-35-2D040 .................. Trichloroethylene ........ 79-01-6D041 .................. 2,4,5-Trichlorophenol. 95-95-4D042 .................. 2,4,6-Trichlorophenol.. 88-06-2D017 .................. 2,4.5.TP (Silvex) .......... 93-76-5D043 ........ Vinyl chloride ............... 75-01-4

'Hazardous waste number.2 Chemical abstracts service number.

b. Inorganic Constituents. Among theconstituents that were proposed forinclusion in the TC were eight inorganicconstituents that are currently regulatedin the EPTC. Because EPACML does notcurrently accommodate metallic species,it cannot be used to predict DAFs for.these constituents. Therefore, theAgency is today retaining the regulatory

.........................................................................

0.10.130.0030.0010.130.724.3

36.05.00.060.21.48.67.20.133.6

14.45.01.05.0

10.01.30.11.5

14.40.07

30.01.20.075.80.300.140.05



levels for these constituents at theircurrent levels. When the MINTEQmodel (see IlI.B.5.c) is available toaccommodate these constituents, theAgency will reconsider their regulatorylevels and propose new ones, if sowarranted.

B. Selection of DAFsThe selection of the appropriate DAF

for the constituents addressed in today'srule is based on the municipal landfillscenario, as proposed. However, basedon comments on fate processes thatwere not appropriately considered in themodel, several constituents have beenomitted from the proposed list ofconstituents-specifically, those thatmay hydrolyze to more than a negligibleextent and those for which the steady-state assumption may not beappropriate.

For the remaining constituents, theAgency believes that a DAF of 100 isappropriate for establishing regulatorylevels in today's rule. The basis for thisconclusion is explained in SectionIII.E.4.d.

C. Analytical ConstraintsThe regulatory levels for the

compounds proposed for inclusion in theTC span approximately five orders ofmagnitude (i.e., from the low parts perbillion to 100 parts per million). Thecalculated regulatory levels for three ofthese compounds (2,4-dinitrotoluene,hexachlorobenzene, and pyridine) arebelow the concentrations measurableusing currently available methods.

EPA believes that the appropriateway to deal with a calculated regulatorylevel that is below the analyticaldetection limit is to use (for theregulatory level) the lowest level ofdetection that can be attained. Thelowest level of a particular chemicalthat can be reliably measured withinacceptable limits of precision andaccuracy under routine laboratoryoperating conditions is that chemical's"quantitation limit." A quantitation limitis determined through such studies asmethod performance evaluations:

If data from interlaboratory studiesare unavailable, quantitation limits areestimated based on the detection limitsand an estimated multiplier thatrepresents a practical and routinelyachievable level with relatively highcertainty that the reported value isreliable. EPA proposed to use a value offive times the analytical detection limitas the quantitation limit and to set theregulatory level at the quantitation limitfor those compounds for which the -calculated regulatory level is below thequantitation limit, and interlaboratorystudies were not available.

Because TCLP extracts are aqueous innature, the quantitation limits used inthis rule are based on the presence ofthese compounds in a water matrix. TheAgency received many comments on theuse of the quantitation limit as theregulatory level for the three compoundswith health-based thresholds below thatlevel. Most comnienters expressedconcern that quantitation limits basedon analysis of the constituent in awatermatrix may not be achievable in morecomplex samples. The commentsdiscussed potential complications thatcould hamper analysis of various kindsof wastes and recommended that EPAwork toward determining actualquantitation limits on real wastes.

The Agency agrees that the ability toachieve the quantitation levels listed inthe proposed rule is strongly influencedby the type of waste that is beinganalyzed. However, determination of amatrix-dependent quantitation limitwould require analysis of a wide varietyof wastes. EPA believes that it would beimpractical to perform such waste-specific analyses at this time. Therefore,EPA has chosen to use the proposeddefinition (i.e., five times the methoddetection limit) for the quantitationlimit.

A number of commenters addressedthe issue of the generic multiplier usedto derive the quantitation limit. Severalcommenters recommended using 10 to25 times the detection limit as theregulatory level, while a few •commenters supported setting the

regulatory level at the detection limit-itself, to provide what they believewould be greater environmentalprotection.

The Agency is working to improve thesensitivity of analytical methods toprovide increased protection of humanhealth and the environment. Analyticaldetection limits are, by definition, notroutinely achievable under averagelaboratory conditions. Thus, aregulatory level set at the detection limitwould be difficult for the Agency toenforce and would make it difficult forthe regulated community to demonstratecompliance. To provide a consistentlyenforceable regulatory limit whileproviding assurance that those wastesthat clearly pose hazards are subject tosubtitle C requirements, the Agency willset the regulatory level at five times thedetection limit. The Agency has a highdegree of confidence in setting theregula'tory level at the quantitation limit(i.e., five times the detection limit)because other programswithin theAgency have successfully used thismethod in the past to set regulatorylevels (e.g., the Contract LaboratoryProgram under the Superfund Program).

Comments on the use of thequantitation limit are addressed moreextensively in the testing methodsbackground document.

D. Final Regulatory Levels

The regulatory levels beingpromulgated today are equal to theproduct of each constituent's toxicitythreshold and the DAF or thequantitation limit. These regulatorylevels are presented in Table IV-3.These levels are designed to identifywastes that clearly pose a hazard anddefine those wastes as hazardous.However, it should be noted that wastesthat do not exhibit-this characteristic(e.g., result in TCLP levels that are lessthan the regulatory levels) are notnecessarily nonhazardous and may belisted as a hazardous waste or becomehazardous under other hazardous wasteijharacteristics.

TABLE IV-3.-ToxICITY CHARACTERISTIC CONSTITUENTS AND REGULATORY LEVELS

CAS Re gulatoryEPA HW number Constituent Number 2 lee rgL

D004 ...........................................................................................D005 .................................................................................................DO18 .................................................................................................D006 ............................................................................................D019 ................................................................................................D020 .................................................................................................D021 .................................................................................................D022: .............................................. a .........................................0007 ................................................................................................0023 .................................................................................................

Arsenic ............... ............... : . ...................Barium ...............................................................................................................Benzene ..................................................................................................................Cadm ium ..................................................................................................................Carbon tetrachloride ...............................................................................................Chlordane ...............................................................................................................Chlorobenzene ............................ ...................................................................Chloroform ...............................................................................................................Chrom ium ......................................................................... 1 .......................................0-Cresol ....................................................................................................................

7440-38-27440-39-3

71-43-27440-43-9

56-23-557-74-9

108-90-767-66-3

7440-47-395-48-7

5.0100.0

0.51.00.50.03

100.06.05.0

4200.0

11845


11846 Federal Register / Vol. 55, No, 61 / Thursday, March 29, 1990 / Rules and Regulations

TABLE IV-3.-ToxICITY CHARACTERISTIC CONSTITUENTS AND REGULATORY LEVELS-Continued

EPA HW number Constituent CAS ReulatoryNumber 2 level (mg/L)

D024 ............................. .........................................................D025 ................................................................................................D026 .................................................................................................D016 ........................................................................ ........................D027 ................................................................................................D028 ................................................................................................D029 ........................................................................................D030 .................................................................................... : ............D012 ................................................................................................D031...... ....................................................................................D032 .................................................................................................D033 ................................................................................................D034 ................................................................................................D008 ...........................................................................................D013 ...........................................................................................D009 ...........................................................................................D014 ................................................................................ .D035 ........................................................................................D036 .................................................................................................D037 .................................................................................................D038 .................................................................................................I ..

ii- .. . . ..................................................................................................................

p-Cresol ..................................................................................................................Cresol .....................................................................................................................2,4-D ......................................................................................................................1.4-Dichlorobenzene ..............................................................................................

18 ...........................................................................................I,?-

2.4-

Methyl ethyl INitrobenzenePentachloropPyridine .........

................................................... I lu nl ................................ ........................................ ............ . . .Silver .................................................................................................................Tetrachloroethylene ..........................................................................................Toxaphene ...................................................................Trichloroethylene ..................................................................................................2,4,5-Trichlorophenol ...........................................................2,4,6-Trichlorophenol .............................................................................................2,4,5-TP (Sitvex) ...............................................................................................Vinyl chloride ....................... ............................................................................

108-39-4106-44-5

94-75-7106-46-7107-06-275-35-4

121-14-272-20-876-44-8

118-74-187-68-367-72-1

7439-92-158-89-9

7439-97-672-43-578-93-398-95-387-86-5

110-86-17782-49-27440-22-4

127-18-48001-35-2

79-01-895-95-488-06-293-72-175-01-4

4200.04200.04200.0

10.07.50.50.7

30.130.020.008

'0.130.53.05.00.40.2

10.0200.0

2.0100.035.0

1.05.00.70.50.5

400.02.01.00.2

' Hazardous waste number.2 Chemical abstracts service number.3 Quantitation limit is greater than the calculated regulatory level. The quantitation limit therefore becomes the regulatory level.4If o-m-, and p-cresol concentrations cannot be differentiated, the total cresol (D026) concentration is used. The regulatory level for total cresol is 200 mg/L.

V. Implementation

This section is intended to assist theregulated community in understandingtheir regulatory obligations for managingTC wastes. Responses to comments andan analysis of issues related toimplementation were presented insection III.K.

The first step in a solid waste.generator's decision making processmust be to determine whether or notparticular wastes are hazardous (40 CFR262.11). If a waste is excluded fromregulation under 40 CFR 261.4, or if it isa listed hazardous waste under subpartD of 40 CFR part 261, then no furtherdetermination is necessary. If a waste isneither excluded nor listed, a generatormust determine whether the wasteexhibits any of the characteristics ofhazardous waste; the ToxicityCharacteristic is one such characteristicof hazardous waste. A generator maydetermine if a waste exhibits acharacteristic either by testing the wasteor applying knowledge of the waste, theraw materials, and the processes used inits generation. 1

When a waste is determined to behazardous, handlers of that waste must

comply with any applicable standards inparts 262, 263, 264, 265, 266, 267, 268 and270 of chapter 40. Table V-1 presents animplementation timeline for the TC. Theremainder of this section illuminatesfive implementation concerns: stateauthority, integration of today's TC withthe existing EPTC, notification,

'permitting, and compliance date.

TABLE V-1.-IMPLEMENTATION TIMELINEFOR THE TOXICITY CHARACTERISTIC

0 Months: Publication in the FederalRegister.

3 Months:Generators of 1000 kg/mo or more andTSDFs who have not previously notifiedsubmit 3010 Notification to EPA.

6 Months:" Facilities wishing to avoid entering the

RCRA program cease managing newlyregulated TC hazardous wastes. Unitsthat were receiving TC -hazardouswastes must cease further receipt inorder to avoid regulation under SubtitleC.

" Large quantity generators begin tocomply with all applicable Subtitle Cregulations for newly regulated TCwastes.

" Newly regulated facilities.-Submit Part A permit application.

" Already regulated facilities.-Interim Status Facilities: submit

amended Part A permit application.-Permitted TSDFs: submit Class 1

permit modification.12 Months:

" Small quantity generators begin' tocomply with all applicable Subtitle Cregulations for newly regulated TCwastes.

" Already regulated facilities.-Permitted TSDFs: submit Class 2 or

Class 3 permit modifications.18 Months:

* Newly regulated land disposal units:-submit Part B permit application andcertifications to EPA-Interim Status ter-minates for those land disposal units*that did not submit their Part B permitapplication and certifications by thisdate.

A. State Authority

1. Applicability of Final Rule inAuthorized States

Under section 3006 of RCRA, EPAmay authorize qualified states to

S15 ............

D040 ............D041 ............D042 ............D017 ............flflAq

.......................................................................................- I

.................................................



administer and enforce the RCRAprogram within the state (see 40 CFRpart 271 for the standards andrequirements for authorization).Following authorization, EPA retainsenforcement authority under sections3008, 7003 and 3013 of RCRA, althoughauthorized states have primaryenforcement responsibility. Prior toHSWA, a state with final authorizationadministered its hazardous wasteprogram entirely in lieu of the federalprogram. The federal requirements nolonger applied in the authorized state,and EPA could not issue permits for anyfacilities in a state that was authorizedto issue permits. When new, morestringent federal requirements werepromulgated or enacted, the state wasobligated to enact equivalent authoritywithin specified time frames. Newfederal requirements did not take effectin an authorized state until the stateadopted the requirements as state law.

In contrast, under section 3006(g) ofRCRA, 42 U.S.C. 6926(g), newrequirements and prohibitions imposedby HSWA take effect in authorizedstates at the same time that they takeeffect in nonauthorized states. EPA isdirected to carry out those requirementsand prohibitions in authorized states,including the issuance of permits, untilthe state is granted authorization to doso. While states must still adopt HSWA-related provisions as state law to retainfinal authorization, the HSWArequirements are implemented by EPAin authorized states in the interim.

Today's rule is promulgated pursuantto RCRA section 3001(g) and (h). Theseprovisions were added by HSWA.Therefore, the Agency is adding therequirement to Table 1 in § 271.1(j),which identifies the federal programrequirements that are promulgatedpursuant to HSWA and that take effectin all states, regardless of theirauthorization status. States may applyfor either interim of final authorizationfor the HSWA provisions identified inTable 1, as discussed in the followingsection of this preamble.

2. Effect on State AuthorizationAs noted above, EPA will implement

today's rule in authorized states untilthey modify their programs to adoptthese rules and the modifications areapproved by EPA. Because the rule ispromulgated pursuant to HSWA, a state

submitting a program modification mayapply to receive either interim or finalauthorization under section 3006(g)(2) or.3006(b), respectively, on the basis ofrequirements that are substantiallyequivalent or equivalent to EPA's. Theprocedures and schedule for stateprogram modifications for either interimor final authorization are described jn 40CFR 271.21. It should be noted that allHSWA interim authorizations willexpire January 1, 1993 (see 40 CFR271.24(c)).

40 CFR 271.21(e)(2) requires thatstates with final authorization mustmodify their programs to reflect federalprogram changes, and they mustsubsequently submit the modificationsto EPA for approval. The deadline forstate program modifications for this ruleis July 1, 1991 (or July 1, 1992, if a statestatutory change is needed). Thesedeadlines can be extended in certaincases (40 CFR 271.2i(e)(3)). Once EPAapproves the modification, the staterequirements become subtitle C RCRArequirements. States with authorizedRCRA programs may already haverequirements similar to those in today'srule. These state regulations have notbeen assessed against the federalregulations being promulgated today todetermine whether they meet the testsfor authorization. Thus, a state is notauthorized to implement theserequirements in lieu of EPA until thestate program modification is approved.Of course, states with existing standardsmay continue to administer and enforcetheir standards as a matter of state law.In implementing the federal program,EPA will work with states undercooperative agreements to minimizeduplication of efforts. In many cases,EPA will be able to defer to the states intheir program implementation efforts,rather than take separate actions underfederal authority.

States'that submit their officialapplications for final authorization lessthan 12 months after the effectie dateof these standards are not required toinclude standards equivalent to thesestandards in their application. However,the state must modify its program by thedeadline set forth in § 271.21(e). Statesthat submit official applications for finalauthorization 12 months after theeffective date of these standards mustinclude standards equivalent to thesestandards in their application. The

process and schedule for final stateauthorization applications is describedin 40 CFR 271.3.

B, Integration of Today's Final Rulewith Existing EPTC

As explained above, because this ruleis promulgated pursuant to HSWA, itwill be effective six months from todayin both authorized and unauthorizedstates and will be implemented by EPAuntil states receive authorization for thisrule. Thus, beginning on the effectivedate, large quantity generators thatgenerate TC waste in all states areresponsible for complying with theappropriate requirements. However, therule promulgated today also revises anexisting RCRA rule defining hazardouswastes that authorized states have beenimplementing for some time. The twoprincipal changes in the rule are therevision to the leaching procedure, byreplacing the EP-with the TCLP, and theaddition of constituents for which theleachate will be analyzed. Thediscussion below and Table V-2describe how state implementation ofthe existing EPTC will be integratedwith EPA implementation of the TC aspromulgated today...

1. Facilities Located in AuthorizedStates

There are three types of facilitieslocated in authorized states which areaffected by today's rule: facilities whichare already operating under a RCRApermit, facilities which are alreadyoperating under interim status, andfacilities which are subject to RCRApermit requirements for the first time asa result of today's rule. Permitted andinterim status facilities can also beaffected by today's rule in three distinctways: (1) The facility may already bemanaging wastes that are hazardousunder the existing EPTC, (2) the facilitymay already be managing wastes thatare hazardous under the existing EPTCbut which also exhibit the toxicitycharacteristic for a new constituent(s)under today's rule (and thus the wastewould have a new waste code), or (3)the facility may be managing a solidwaste which is newly subject toregulation as a result of today's revisionof the TC. Table V-2 summarizes theinitial filing requirements and applicablestandards for each category of facility.

11847



TABLE V-2.-INTEGRATION OF TC WITH EXISTING EPTC .

7 'I-~ r1 1 Applicable permittingStatus of State authorization Facility status Type of waste What to file Where to file Apstandards

1. Authorized State ............. I A. Permitted ...............

11. No;iauthoized State ................

B. Interim Status.

C. Newly-regulated....

A. Permitted ..............

B. Interim Status.

1. Regulated EPAwaste w/no newconstituents underrevised TC.

2. Regulated EP wastew/new constituents.

3. Previouslyunregulated waste in:

-Already reaulatedunit..

-Previouslyunregulated unit.

1. Regulated EP wastew/no newconstituents underrevised TC.

2. Regulated EP wastew/new constituentsunder revised TC.

3. Previouslyunregulated waste.


2. Regulate EP wastew/new constituentsunder revised TC.

3. Previouslyunregulated waste in:

-Already regulatedunit.

-Previouslyunregulated unit


2. Regulated EP wastew/new constituentsunder revised TC.

3. Previouslyunregulated waste.

C. Newly-regulated .... ........................ .................

NA ....... .............................. NA...............I State permit standards.

Class 1 permitmodification under 40CFR 270.42.

Class I permitmodification under 40CFR 270.42.'

EPA Regional Officeand State.

EPA Regional Qfficeand State.

State permit standards.

......... .......................... .................... I ......... .............................. State permit standards.

............................................. . .... ................................ 40 CFR Part 265.,

NA ................NA................ State interim statusstandards.

Revised Part A under40 CFR 270.72.

Revised Part A under40 CFR 270.72V

Part A and 3010 under40 CFR 270.70.3

N A ......................................

Class 1 permitmodification under 40CFR 270.42.

Class 1 permitmodification under 40CFR 270.42.'



EPA Regional Office .......

State interim statusstandards.

40 CFR Part 265.

40 CFR Part 265.

NA ...................................... 40 CFR Part 264.

EPA Regional Office. 40 CFR Part 265.

EPA Regional Office.

NA ......................................NA....................

Revised Part A under40 CFR 270.72.

Revised Part A under40 CFR 270.72.2

Part A and 3010 under40 CFR 270.70.3

EPA Regional Office.......

EPA Regional Office .......

EPA Regional Office.

40 CFR Part 264.

40 CFR Part 265.

40 CFR Part 265.

40 CFR Part 265.

40 CFR Part 265.

40 CFR Part 265.

I Facility may also need to receive a Class 2 or Class 3 modification under CFR 270.42.I If newly regulated waste is being managed in a land disposal unit, facility may need to submit certification of compliance within one year under 40 CFR 270.73.

If facility is a land disposal facility, Part B permit application and certfication of compliance must be submitted within one year under RCRA Section 3005(e)(3)and 40 CFR 270.73.

For facilities which have beenmanaging EPTC wastes under anauthorized state program and theconstituents exhibited by the wastes areunchanged under today's rule, (i.e., nowaste code change is necessary), suchinterim status and permitted facilitieshave no changes to file with permittingauthorities. Similarly, since theregulatory status of the waste isunchanged, management of that wastewill continue to be regulated under theauthorized state standards. The onlyeffect of today's rule on such facilities isthat the facility must use the TCLP whentesting for toxic constituents. However,use of the EP in addition to the TCLP

may continue to be required as a matterof state law.

For facilities which have beenmanaging E1ITC wastes under anauthorized state program and theconstituents exhibited by the wasteshave changed as a result of today's rule,the facility will need to change thewaste code assigned to its TC wastes.Permitted facilities must submit permitmodifications to EPA reflecting the newwastes codes. Because EPA mustimplement this rule until the state isauthorized to do so, the permittee mustcomply with federal permit modificationprocedures under 40 CFR 270.42 ratherthan state permit modificationprocedures. However, because the

permit undergoing modification is mostlikely a joint EPA-state RCRA permit, acopy of the modification request shouldalso be submitted to the authorizedstate. Similarly, interim status facilitiesmust submit a revised part A permitapplication to EPA pursuant to 40 CFR270.72, with a copy to state permittingauthorities. Although these facilitiesmust make appropriate waste codemodifications to reflect the new TCconstituents, the wastes are alreadyregulated as EP wastes under theauthorized state program. Accordingly,such wastes are not subject to any newmanagement requirements as a result ofthis rule and must continue to complywith appropriate authorized state



requirements for management of thesewastes.

Some permitted and interim statusfacilities in authorized states will bemanaging wastes which will becomehazardous as a result of today's rule.These facilities must also submit permitmodifications or part A permitapplication revisions to EPA. However,because these wastes were previouslyunregulated under RCRA, they alsowere not regulated under the authorizedstate program. As a result, if thesewastes are in a previously unregulatedunit, they will be subject to the self-implementing Federal standards forhazardous wastes management at 40CFR part 265 until permit issuance (forinterim status facilities) or modification(for permitted facilities). After permitissuance or modification, the Federalpermitting standards at 40 CFR part 264will apply to these wastes (or the statepermitting standards if the permit isultimately issued or modified by a stateauthorized for the TC). However, if thewastes are at a permitted facility in aunit that is already regulated, that unitwill continue to comply with theapplicable 40 CFR part 264 (or stateequivalent) standards.

Facilities in authorized states whichare newly subject to RCRA permitrequirements as a result of today's rulemust obtain an EPA identificationnumber and submit their part A permitapplication and section 3010 notificationto EPA in order to obtain interim status(see 40 CFR 270.70). Such facilities aresubject to regulation under 40 CFR part265 until a permit is issued by EPA or astate authorized for the TC.

2. Facilities Located in UnauthorizedStates

There are also three types of facilitieslocated in unauthorized states which areaffected by today's rule: alreadypermitted facilities, facilities operatingunder interim status, and facilitiesnewly subject to RCRA permitrequirements under today's rule. As inauthorized states, some of the permittedand interim status facilities have beenmanaging EPTC Wastes.

For interim status and permittedfacilities which have been managingEPTC wastes that will exhibit no newconstituents as a result of thereplacement of the EP with the TCLPand the addition of constituenti to theTC, there' willbe no waste codechanges. Accordingly, such facilities donot need to submit permit modificationsor revised permit applications to EPAand will continue to be subject to theapplicable federal standards forhazardous wastp management.

Facilities which have been managingEPTC wastes which exhibit the toxicitycharacteristic for new constituents as aresult of today's changes to the TC mustnotify EPA of the waste code changesfor its TC wastes. Permitted facilitiesmust submit permit modifications toEPA as required under 40 CFR 270.42that reflect the new wastes codes.Interim status facilities must submitrevised part A permit applications inaccordance with 40 CFR 270.72. Thesefacilities must continue to comply withthe applicable federal standards forhazardous waste management.

Permitted and interim status facilitieswhich manage waste that is newlydefined as hazardous waste as a resultof today's rule must also submit permitmodification requests or part A permitapplication revisions to EPA. Facilitiesmust manage these wastes -inaccordance with 40 CFR part 265 or 40CFR part 264 until permit modificationor issuance, depending on whether thewaste is managed in a newly regulatedor previously regulated unit.

Facilities which are newly subject toRCRA permit requirements as a result oftoday's rule must get an EPAidentification number and a part Apermit application to EPA in order toobtain interim status. Such facilities aresubject to regulation under 40 CFR part265 until a permit is issued.

C. Notification

Pursuant to RCRA section 3010, theAdministrator may require all personswho handle hazardous wastes to notifyEPA of their hazardous wastemanagement activities within 90 daysafter the wastes are identified or listedas hazardous. This requirement may beapplied even to those generators,transporters, and TSDFs who havepreviously notified EPA with respect tothe management of other hazardouswastes.

In the June 13, 1986, Federal Registernotice, EPA proposed to waive thenotification requirement for personswho manage TC wastes and havealready (1) notified the Agency that theymanage other hazardous wastes and (2)received an EPA identification number.EPA has decided to waive thenotification requirement as proposed.The Agency believes that, given the vastscope of the TC rule, a notificationrequirement for persons alreadyidentified within the hazardous wastemanagement universe is unnecessary.

EPA is not waiving the notificationrequirement for TC Waste handlers thathave neither notified the Agency thatthey manage hazardous wastes norreceived an EPA identification number.Those persons must notify EPA no later

than June 27, 1990 of these activitiespursuant to section 3010 of RCRA.Notification instructions are set forth in45 FR 12746, February 26, 1980.

D. Permitting

Currently permitted facilities thatmanage TC wastes must submit Class 1permit modifications if they are tocontinue managing the newly regulatedwastes in units that require a permit.The facilities must obtain the necessarymodification by the effective date of therule, or they will be prohibited fromaccepting'additional TC wastes.

Interim status facilities that manageTC wastes in units that require a permitmust file an amended part A permitapplication under 40 CFR 270.10(g) ifthey are to continue managing newlyregulated wastes. The facilities must filethe necessary amendments by theeffective d~ite of the rule, or they will notreceive interim status-with respect to theTC wastes (i.e., they will be prohibitedfrom accepting additional TC wastesuntil permitted).

Newly regulated facilities (i.e.,facilities at which the only hazardouswastes that are managed are newlyregulated TC wastes) must qualify forinterim status by the compliance date ofthe rule in order to continue managingTC wastes prior to receiving a permit.Under 40 CFR 270.70, an existing facilitymay obtain interim status by getting anEPA identification number andsubmitting a part A permit application.To retain interim status, a newly-regulated land disposal facility mustsubmit a part B permit applicationwithin one year after the effective date,of the rule and certify that the facility isin compliance with all applicable groundwater monitoring and financialresponsibility requirements (see RCRAsection 3005(e)(3)).

EPA recently promulgatedamendments to the procedures forpermit modifications for treatment.storage, and disposal facilities (see 53FR 37934. September 28, 1988). Thefollowing discussion assumesimplementation in accordance with thenew rule. EPA will implement the TC byusing the new permit modificationprocedures, consistent with EPA policy(see 53 FR 37933, September 28, 1988).

Under the new regulation in § 270.42,there are now three classes of permitmodifications with different submittaland public participation requirementsfor each class. In § 270.42(g), whichconcerns newly listed or identifiedwastes, a permitted facility that is "inexistence" as a hazardous waste facilityfor the newly listed or identified wasteon the effective date of the notice must

11849


11850 Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990- / Rules and Regulations

submit a Class 1 modification by thatdate. Essentially, this modification is anotification to the Agency that thefacility is handling the waste. As part ofthe procedure, the permittee must alsonotify the public within 90 days ofsubmittal to the Agency.

Next, within 180 days of the effectivedate, the permittee must submit a Class2 or 3 modification to the Agency. Apermittee may submit a Class 2modification if the newly regulatedwaste will be disposed in existing TSDunits and will not require additional ordifferent management practices fromthose authorized in the permit. A Class 2modification requires public notice bythe facility owner of the modification-request, a 60 day public commentperiod, and an informal meetingbetween the owner and the publicwithin the 60 day period. The ruleincludes a "default provision," so thatfor Class 2 modifications, if the Agencydoes not make a decision within 120days, the modification is automaticallyauthorized for 180 days. If the Agencydoes not reach a decision by the end ofthat period, the modification ispermanently authorized. If the newlyregulated waste requires additional ordifferent management practices, a Class3 modification is required. The initialpublic notification and public meetingrequirements are the same as for Class2. However, after the end of the publiccomment period, the Agency willdevelop a draft permit modification,open a public comment period of 45days and hold a public hearing.

E. Compliance Date

The Agency is promulgating twodifferent compliance dates for twodifferent categories of TC wastegenerators: (1) All generators of greaterthan 100 and less than 1,000 kg/month ofhazardous waste (small-quantitygenerators) must come into compliancewith subtitle C requirements formanagement of their TC waste withinone year from today; and (2) allgenerators of 1,000 kg/month or more ofhazardous waste and TSDFs arerequired to comply with all subtitle Crequirements for TC wastes within sixmonths from-today, on the effective dateof the rule. Thus the EPTC remains ineffect until six months after today's datefor large quantity generators and TSDFs,and remains in effect for 12 months aftertoday's date for small quantitygenerators. The generator quantityrefers to all of a generator's hazardouswaste, not just newly hazardous TCwaste.

Further discussion of the Agency'sreasons for promulgating an extendedcompliance date for small-quantity

generators is provided in section III.K ofthis preamble. In summary, the Agencybelieves that allowing an additional sixmonths for small quantity generators tocome into full compliance with the.TCwill serve two purposes. First, it willallow the Agency time to educate smallquantity generators on the RCRA ruleswhile, at the same time, allowing theAgency, to focus immediateimplementation efforts on large volumesof hazardous waste. Second, it willprovide the necessary time for smallquantity generators to comply withsubtitle C requirements as a result of theTC.

VI. Regulatory Requirements

A. Introduction

This portion of the preamble discussesthe analyses required by ExecutiveOrder No. 12291 and the RegulatoryFlexibility Act. The Agency is requiredunder the Executive Order to estimatethe costs, economic impacts, andbenefits of "major" rules by conductinga regulatory impact analysis (RIA).Recognizing the potential of the ToxicityCharacteristic (TC) rule to affect a broadspectrum of American industry, EPAprepared an RIA comparing severalregulatory alternatives. Based'on theresults of this analysis, the Agencyconcluded that this final regulation is amajor rule. Section VI.B presents themethodology and results of the RIA.

The Regulatory Flexibility Actrequires the Agency to assess smallbusiness impacts resulting fromregulations. The analysis of smallbusiness impacts indicated that the TCrule would not have a significant impacton small businesses, and therefore aformal regulatory flexibility analysiswas not prepared. Section VI.Caddresses potential effects on smallbusinesses.

The Agency received'many commentson the RIA for the June 13, 1986proposal. A summary of comments,along with Agency responses, isincluded as section VI.D. Section VI.Ediscusses requirements under thePaperwork Reduction Act.

Details of the regulatory impactanalysis and small business analysis areavailable in the RIA document for thefinal rule (Ref. 8). This final rule wassubmitted to the Office of Managementand Budget for review as required byE.O. No. 12291.

B. Regulatory Impact Analysis

1. Executive Order No. 12291

Executive Order No. 12291 requiresEPA to assess the effect of Agencyactions during the development ofregulations. Such an assessment

consists of a quantification of thepotential costs, economic impacts, andbenefits of a rule, as well as adescription of any beneficial or adverseeffects that cannot be quantified inmonetary terms. In addition, ExecutiveOrder No. 12291 requires that regulatoryagencies prepare a regulatory impactanalysis (RIA) for major rules. Majorrules are defined as those likely to resultin (1) an annual cost to the economy of$100 million or more; (2) a majorincrease in costs or prices for consumersor individual industries; or (3) significantadverse effects on competition,employment, investment, innovation, orinternational trade.

EPA prepared an RIA comparing thefinal TC rule with several regulatoryalternatives. Based on the RIA, EPAestimates that the final TC rule is amajor rule with annual compliance costsof between $130 million and $400million. The analysis was conductedbased on the Office of Management andBudget's "Interim Regulatory ImpactAnalysis Guidance" and EPA's"Guidelines for Performing RegulatoryImpact Analyses."

2. Basic Approach

In the final rule, EPA is amending itshazardous waste identificationregulations under Subtitle C of theResource Conservation and RecoveryAct (RCRA) by refining and expandingthe existing Extraction ProcedureToxicity Characteristic (EPTC). Theresulting TC includes a new extractionprocedure (the Toxicity CharacteristicLeaching Procedure or TCLP) and 25new organic constituents in addition tothe 14 existing EPTC constituents.Wastes exhibiting the TC, based onconcentrations of constituents in theTCLP extract, are designated ashazardous wastes and are brought undersubtitle C regulation.

EPA estimated the costs, economicimpacts, and benefits of the final rule.and of a number of major regulatoryalternatives to the rule. Only theanticipated effects of the final rule arepresented in this preamble-, results forthe regulatory alternatives are discussedin the RIA. In presenting the results ofthe analysis, the Agency has presentedrange estimates for costs, economicimpacts, and benefits to express theuncertainty associated with certainanalytical assumptions.

In order to gauge the effects of thefinal rule, EPA first identified wastesand industries which would be affectedby the rule. Incremental costs foraffected facilities were estimated basedon the change in waste managementpractices which would be required once



the wastes became hazardous. Theseincremental costs were aggregated toestimate national costs of the rule.

Economic impacts on facilities werebased on a comparison of facilitycompliance costs with costs ofpfoduction and cash from operations.The potential for facility closures wasalso examined.

Benefits, like costs, were based onrequired changes in waste management.practices. Benefit measures includedhuman health risk reduction, resourcedamage reduction, and cleanup costsavoided. Facility-level benefit estimateswere aggregated to obtain nationalbenefits.

Section VI.B.3, below, presents themethodology used to estimate costs,economic impacts, and benefits. It alsobriefly describes the sensitivity analysesthat were conducted to determine thesignificance of key analyticalassumptions; these sensitivity analysesare discussed in more detail in the RIA.Limitations of the analytical approach(e.g., assumptions which are likely tooverstate, understate, or createuncertainty in results) are discussed inthe RIA. Results of the analysis of costs,economic impacts, and benefits areprovided in section VI.B.4.

3. MethodologyThe methodology for the RIA is

presented'in several parts. First, theprocedure for identifying wastes andfacilities affected by the TC isdiscussed. Next, the development ofnational cost estimates is presented. Thesection on economic impactmethodology describes the criteria usedin gauging impacts on the regulatedcommunity. Following that is a sectionthat presents several alternativemeasures of benefits of the rule. The lastsection describes the methodology foranalysis of used oil.

a. Determination of Affected Wastesand Facilities. The first step inestimating the impacts of the rule was todetermine which wastes and facilitieswould be affected by the rule, based onwaste characteristics, quantities, andmanagement practices. No single datasource contained all of this information,and none of the data were facility-specific. Therefore, the Agencyassembled aggregated data (e.g., byindustrial sector) from separate sourcesand used it to draw inferences onfacility-level impacts.

Data on waste characterization andvolume came primarily from a series ofTC industry studies. (Ref. 19 through 29)These studies were conducted for majorindustrial categories identified as likelyto generate significant quantities of TCwastes; other sectors, generating smaller

quantities of potentially affected waste,were not addressed. Standard IndustrialClassifications (SICs) for the industrialsectors studied range between the two-digit and four-digit levels. The industriesprofiled are shown in Table VI-1.

TABLE VI-I.-POTENTIALLY AFFECTED IN-DUSTRIES CONSIDERED IN RIAS FORTHE PROPOSED AND FINAL TC RULES

Industry SIC' Pro-posed Final

Textile Mills 2 ........... 22 .................. XLumber and Wood 2421, 2499 ..................... X

Products.2

Pulp and Paper 2 .... 261,262, 263 .......... X266.

Printing and 27 ................. xPublishing.

Plastics Materials 2821 ................. X Xand Resins.

2

Synthetic 2822 ................. X XRubber.2.

Synthetic Fibers.2 .. , 2823, 2824................... X

Pharmaceuticals.'... 283 ................... X XSoaps and Other 2841 .................. X

Detergents.Surface Active 2843 .................. X

Agents.Paints and Allied 2851 ................. X

Products.Organic 2865, 2869 X X

Chemicals.2Agricultural 2879 .................. X

Chemicals.Petroleum 2911 ................. X X

Refining.2Miscellaneous 2992 ............... . X

Petroleum andCoal Products.'

Rubber and 30 ................. XMiscellaneousPlasticsProducts.2

Non-Ferrous Wire 3357 .................. XDrawing andInsulation.

Machinery and 34 through 39 ................ XMechanicalProducts.

Pipelines, except 461 ................ .XNatural Gas.'

Electrical Services.. 4911 ................ XWholesale 517 ................ .X

PetroleumMarketing.'

ISICs listed are those defining the group consid-ered in this analysis. SICs given at the two-digit orthree-digit SIC level indicate that the analysis appliesto all four-digit SICs contained within the broadercategory

2 Included in detailed quantitative analysis for thefinal RIA.

The industry studies provided dataincluding waste type (wastewater,sludge, solid process residual, or organicliquid), waste quantity, constituentconcentration ranges and distributions,and number of generating facilities. Thedata in the studies were based primarilyon EPA's effluent guidelines reports,supplemented by best engineeringjudgement and data received incomments on the proposed rule or infollow-up correspondence (Refs. 30 and31). Most of the wastes which were

included were related to wastewatertreatment; there was relatively littledata on process residuals. Wastes whichwere already hazardous by virtue of alisting or characteristic (e.g., the EFl'C).were not included. Due to lack of data,certain types of wastes were notincluded in the analysis (e.g.,contaminated soil, off-spec products,contaminated debris).

It is particularly difficult to predict thebehavior of oily wastes in the TCLP test.For the purpose of deriving upper boundestimates of costs, economic impacts,and benefits, one assumption that EPAadopted was that oily non-liquid wasteswould not present filtration problems inthe TCLP (i.e., that the oily phase passesthrough the filter and hazardousconstituents in the oil phase leach to thetest extract) and that if extractconcentrations exceeded regulatorylevels, these wastes would fail the TC.As a basis for lower bound estimates forcosts, economic impacts and benefits,the Agency assumed that no oily wasteswill be caught by TC regulation becausethe oily phase (and corresponding highlevels of toxic constituents) would notfilter through to the extract in the TCLP.

Due to the lack of facility-specificwaste generation data, certainassumptions had to be made to derivethe quantity of each wastestream perfacility. First, potentially affectedfacilities within each industrial sectorwere split between small (with less than50 employees) and large (with 50employees or more) facility sizecategories based on 1982 Census ofManufacturers data on the number offacilities by size category. (The 1982Census data were the most recentavailable.) Second, the total quantity'ofpotentially affected waste wasdistributed between small and largefacilities based on Census ofManufacturers data on the value ofshipments for the small and large sizecategories. Using the distribution offacilities and of total waste quantitybetween small and large size categories,EPA estimated wastestream quantityper facility for small and large facilities.

EPA conducted a sensitivity analysisin order to test the sensitivity of resultsto the assumed distribution of wastesbased on value of shipments. Since thedivision of waste quantities based onvalue of shipments resulted in mostwaste being generated by largefacilities EPA tested the alternativeassumption that waste quantities weresplit evenly between the large and smallfacility size categories in each industry.(Results of sensitivity analyses arepresented in section VI.B.4.)

11851.



Baseline management practices (i.e.,management practices in the absence ofthe regulation] were derived primarilyfrom the Screening Survey of Industrialsubtitle D Establishments. (Ref. 16.) Thissurvey provided information on thepercent of facilities, by industrial sector,which manage non-hazardous wasteson-site in landfills, surfaceimpoundments, waste piles, and landapplication units. Other baselinemanagement practices were notspecifically identified in the survey;therefore, EPA had to use knowledge ofpotentially affected TC wastes toidentify these other practices andestimate the percentage of facilitiesusing them.

In the case of non-wastewaters, theother practices considered includedmanagement in off-site landfills andland application units. For wastewaters,the other baseline practices includedmanagement in tanks as part of awastewater treatment system, directdischarge under a NPDES permit, orindirect discharge to a Publicly OwnedTreatment Works. These otherwastewater management practices wereassumed to be permissible undersubtitle C; therefore it was assumed thatfacilities using these practices forwastes which were identified ashazardous by the TC would not beaffected by the TC rule. EPA examinedthe sensitivity of results to thisassumption by assuming, alternatively,that all wastewaters were managed onsite in subtitle D surface impoundments.

For organic liquids, EPA determined,based on the Office of Solid Waste'sIndustry Studies Database, that the mostlikely baseline management practiceswere recycling and burning. EPAassumed that incremental managementcosts for these wastes would not besignificant and therefore did not includethe wastes in the analysis.

By combining the wastecharacterization and volume data withthe management practice data, it waspossible to estimate, by industrialsector, the amount of waste and thenumber of facilities potentially affectedby the TC.

In order to determine the quantity ofeach wastestream which would beaffected by the TC, the regulatory levelsfor constituents in the waste werecompared with the estimatedconcentration distributions, derivedfrom the TC industry studies, forconstituents in the waste leachate. Theconstituent which caused the largestpercentage of the wastestream to fail theTC was designated as the "cost-driving"constituent, and the quantity exhibitingthe TC due to the presence of thatconstituent was used as the affected

quantity. EPA tested the sensitivity ofresults to the assumption that wastewould fail for a single drivingconstituent by adding the percentagesfailing for all constituents (up to 100percent).

Due to the lack of facility-specificdata, it was assumed that thepercentage of facilities affected by the

*TC for a particular wastestream wouldequal the percentage of the total wastefailing the TC. (For example, if 25percent of a wastestream failed, it wasassumed that 25 percent of the facilitiesgenerating the waste would be affectedand that all of the wastestream at each,affected facility would fail.] In order totest the importance of this assumption,EPA adopted two alternativeassumptions as sensitivity analyses: forany percentage of waste failing (exceptfor 0 and 100 percent, where clearly nofacilities or all facilities would beaffected), the percentage of facilitiesaffected would be 10 percent or,alternatively, 90 percent.

The effects of potential productionprocess changes in response to the rulewere not addressed.

b. Cost Methodology; EPA estimatedboth the social costs and the compliancecosts of the final rule. Social costs donot include transfer payments betweendifferent parties within society (i.e., theydo not include tax payments or above-average profits); the social coststherefore represent the real resourcecosts imposed by the rule on society asa whole. Compliance costs, whichinclude the'effects of taxes and above-average profits, more accurately reflectthe effect of the rule on particularentities within society.

1. Social CostsEPA estimated the national social

costs of the final rule by calculatingbefore-tax incremental managementcosts for affected wastes at modelfacilities and then summing the facilitycosts across industrial sectors.

Before-tax incremental costs werecalculated by subtracting baselinemanagement costs from post-regulatorycosts. Baseline management practiceswere determined as discussedpreviously. Post-regulatory managementpractices were developed based onwaste types and quantities; the least-cost practice among those feasible for awaste was chosen as discussed below.The post-regulatory practices did notinclude potential waste treatmentpractices under the land disposalrestrictions program since land disposalrestrictions requirements for TC Wasteswill not come into effect until after theTC rule is promulgated..Possible post-regulatory management practices, as

well as baseline practices, for TCwastes are shown in Table VI-2.

TABLE VI-2.-BASEUNE AND POST-REGULATORY MANAGEMENT PRACTtCES

Waste type Baseline Post-reguLatorypractice practice

Wastewater ...... On-site Subtitle On-site tankD surface exempt fromImpoundment Subtitle C,

Subtitle Csurfaceimpound-mert.1

orPractice Same as

permiss1ile baseine.3underSubtitle.'.

Non- On-site Subtitle On-site or off-wastewater. D landfill or site Subtitle

land C landfi orapplication landunit or off-site applicationSubtitle D unit.landfill.

Organic liquid . Burning, Same asrecycling, baseline. 3

Dilution and deep-well injection were also con-sidered as post-re ulatory practices but were foundto be more expensive than tank mana.ement

'lnclude management in Subtitle C-exempttanks, direct discharge under a NPDES permit, orindirect discharge to a Publicly Owned TreatmentWorks.

a Since the post-regulatory practice was the sameas the baseline practice, the rule would not affectmanagement of these wastes.

To estimate before-tax baseline andpost-regulatory costs for wastes, EPAfirst estimated the cost per metric tonfor the different on-site and off-sitewaste management practices. Before-taxcosts for on-site management unitsinclude operation and maintenance(O&M) and capital costs. O&M costs areincurred annually for operation andmaintenance of waste treatment ordisposal units. Capital costs includecosts for construction of the unit and fordepreciable assets; these costs, whichassumed an average operating life of 20years, were restated as annual valuesby using a capital recovery factor basedon a discount rate of three percent.RCRA-related costs such as personneltraining, financial assurance, andliability insurance were included asindirect capital costs.

For the subset of subtitle D facilitieswhich could potentially become subtitleC TSDFs in order to manage TC wasteson-site, post-regulatory costs for on-sitemanagement also included correctiveaction costs. Corrective action costs forunits were based on data from the to-be-proposed corrective action subpart Srule RIA, which indicated theprobability of a unit requiring a RCRAfacility assessment, RCRA facilityinvestigation, and corrective actioncleanup. Corrective action costs were



not assigned to facilities which weredetermined to already be subtitle Ctreatment, storage, and disposalfacilities, since units at these facilitieswould already be subject to correctiveaction requirements under subparts Sand F. Like capital costs, correctiveaction costs were converted to annualvalues.

The annualized capital and (asappropriate) corrective action costswere added to yearly O&M costs toderive overall annualized costs for on-site units of various sizes. Theseannualized costs were then divided bythe waste management capacities of theunits to obtain the costs per metric tonfor on-site management in differentunits.

Off-site management costs werebased on commercial hazardous wastemanagement prices, adjusted for theeffects of above-average profits.Shipping costs were included for wastessent off-site. Neither the on-site nor off-site costs included the cost of wastetesting.

Since no data were available on thecombinations of wastestreamsgenerated at particular facilities, EPAused an algorithm to create modelfacilities. In estimating costs for themodel facilities, wastes that wereamenable to co-management weregrouped to identify economies of scale.

Once the costs per metric ton fordifferent types of on-site and off-sitemanagement had been developed andwaste quantities for the model facilitieshad been determined, EPA estimatedeach facility's baseline cost based onthe quantities of waste and the cost permetric ton for the baseline managementpractices identified for the wastes. Thepost-regulatory cost for each facilitywas estimated in a similar way. Thepost-regulatory management practicesfor facilities were selected by comparingthe cost per metric ton for differentfeasible post-regulatory practices forwastes and selecting the least expensivealternative. (This comparison was madebased on compliance costs, rather thansocial costs, as discussed below). EPAthen subtracted baseline costs frompost-regulatory costs to obtain thebefore-tax incremental cost for eachfacility. These before-tax incrementalcosts were then added across industrialsectors to obtain the total (national)social costs of the rule.

EPA examined the possibility thatsome facilities managing wastewaterswould incur costs over and above thecost of switching from management inunlined surface impoundments tomanagement in wastewater treatmenttanks that are exempt from subtitle C.To calculate upper bound costs, the

Agency assumed that facilitiesgenerating large quantities of TCwastewater (over 400,000 metric tonsper year) would not be able to convertexisting non-hazardous surfaceimpoundments to tanks by the effectivedate of the rule (i.e., October 1, 1990)and therefore would become interimstatus facilities under RCRA and subjectto subtitle C closure of anyimpoundments. The upper bound costestimates included costs for subtitle C"landfill closure" of the surfaceimpoundments currently used to manageTC waste. Costs for surfaceimpoundment subtitle C closureincluded pumping of free liquid,solidification of sludges, construction ofa cover system, installation ofupgradient and downgradient groundwater monitoring wells, closurecertification, and potential correctiveaction costs triggered by bringingfacilities with TC surface impoundmentsinto the subtitle C system.

2. Compliance Costs.EPA used the same basic approach to

estimate compliance costs that was usedto estimate social costs except that the-after-tax costs (or revenuerequirements) of management practiceswere used rather than the before-taxcosts, and the price of off-sitemanagement was used rather than thecost of off-site management (to addressabove-average profits). Since thecompliance costs reflect the cost of therule for particular entities within societymore accurately than the social costs do,compliance costs were used indetermining whether it would be lessexpensive for facilities to use on-site oroff-site post-regulatory managementpractices.

Based on the cost analysis discussedabove, EPA estimated the number ofexisting subtitle C treatment, storage,and disposal facilities (TSDFs) electingto manage TC non-wastewaters on siteand the number of subtitle D facilitieswhich would be likely to becomesubtitle C TSDFs in order to managetheir non-wastewaters on-site. (Thefocus was on on-site management ofnon-wastewaters, since it was assumedthat most facilities would be able tomanage wastewaters on site withoutbecoming subtitle C TSDFs.) This wasdone by first determining the number offacilities that would be likely to chooseon-site management as the least-cost

'management practice for non-wastewaters and then estimating howmany of these would be likely to alreadybe subtitle C TSDFs. EPA also estimatedthe number of new subtitle C generators,by determining how many facilitiesWould generate in excess of 100

kilograms per month of TC waste andthen calculating how many of thesefacilities would be likely to already besubtitle C generators.

c. Economic Impact Methodology. Togauge impacts, EPA comparedcompliance costs (discussed previously]with average facility costs of productionand with cash from operations.Financial data were obtained primarilyfrom the Census and Annual Survey ofManufacturers (U.S. Department ofCommerce, Bureau of Census) and wereorganized by Standard IndustrialClassification (SIC) code and facilitysize. Impacts were estimated at thefacility level rather than the firm level,due to lack of data on specific facilitiesand the firms owning them.

Two ratios were used to identifyfa ilities likely to experience adverseeconomic effects: compliance costdivided by cost of production (the COPiatio) and cash from operations dividedby compliance cost (the CFO ratio).These ratios bound possible effects onindividual facilities by examiningimpacts assuming complete pass-through of compliance costs tocustomers, on the one hand, andassuming no pass-through of costs, on.the other. The COP ratio represents thepercentage product price increase forfacility output that would be necessaryif the entire compliance cost,accompanied by facility profit, were tobe passed through to customers in theform of higher prices. A changeexceeding five percent is considered anindication of a significant adverseeconomic impact on a facility. The CFOratio represents the number of times thata facility's gross margin (profil) wouldcover the compliance cost if the facilitywere to fully absorb the cost. For thisratio, a value of less than 20 isconsidered to represent a significantadverse impact.

EPA then performed an analysis onthe.facilities experiencing significanteconomic impacts to identify thepotential for facility closures. Thosefacilities for which the CFO ratio wasless than two were considered likely toclose.

Impacts on significantly affectedproduct markets were addressedqualitatively by examining marketstructure and the ability of facilities topass compliance costs on to customers.

d. Benefits Methodology. The benefitsof the final rule were evaluated by.considering the reduction in humanhealth risk, the reduction in resourcedamage, and future cleanup costsavoided that would result from requiredchanges in management practices foraffected wastes. These benefits

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measures centered primarily on theexposure to contaminants via theground water medium, since this wasthe route of exposure addressed by theTC rule; however, a screening analysisof risks via air, due to emissions fromsurface impoundments, was alsoconducted to gauge the significance ofthese risks.

It is important to point out that thebenefits measures should not be added.The measures provide alternative waysof evaluating benefits of the rule, andsignificant overlap between measuresdoes occur.

EPA estimated benefits on awastestream-by-wastestream basis. Tosimplify the analysis of benefits, EPAemployed a screening analysis toidentify two "risk-driving" constituentsin each wastestream, one a carcinogenand one a non-carcinogen. Theseconstituents were then used indeveloping benefit estimates.

A Monte Carlo modeling approachwas used to simulate fate and transportof the constituents and subsequentexposure to them under a variety ofwaste characterizations, hydrogeologicsettings, and exposure scenarios. Basedon data from EPA's National Survey ofSolid Waste Municipal LandfillFacilities (the "Municipal LandfillSurvey"), it was assumed that only 46percent of facilities had down-gradientwells. EPA examined the sensitivity ofresults to this assumption by assuming,alternatively, that all facilities haddown-gradient wells.

Due to the way in which fate andtransport of constituents was modeled(using an infinite source, steady-statemodel), benefits estimates wereprimarily a function of the number offacilities estimated to manage eachwastestream and constituentconcentrations in the waste;wastestream volumes did not affectbenefits estimates. In contrast, costanalysis results were a function of thenumber of facilities, waste constituentconcentrations, and wastestreamvolumes.

Worst-case estimates of baseline risk,resource damage, and cleanup costswere developed by assuming that thebaseline management practice for bothwastewaters and non-wastewaters wasan unlined, non-hazardous wastelandfill. This is the same assumptionthat was employed by the Agency indetermining regulatory levels for TCconstituents. Post-regulatory risk,resource damage, and cleanup costswere estimated by assuming that thewastes managed as hazardous under theTC would be effectively prevented fromcontaminating ground water and wouldtherefore result in no risk, resource

damage, or cleanup costs; only thosewastes continuing to be managed asnon-hazardous would pose a threat tohuman health or the environment.

For wastewaters, the baseline risk,resource damage, and cleanup cost dueto ground water contamination werebased on concentrations of constituentsin the influents to waste managementunits. Consequently, since volatilizationof constituents from waste managementunits was not accounted for, benefitsdue to reduction in ground watercontamination may be overstated.

The three benefits measures used inthis analysis are discussed separatelybelow.

1. Human Health Risk Reduction

EPA estimated two types of humanhealth risk: risk to the most exposedindividual (MEI) and population risk.Human health risk is defined herein asthe probability of injury, disease, or,death over a given time (70 years) due toresponses to doses of disease-causingagents. The human health risk posed bya waste management practice is afunction of the toxicity of the chemicalconstituents in the wastestream and theextent of human exposure to theconstituents. The likelihood of exposureis dictated by hydrogeologic andclimatic settings at land disposal unitsand by the fate and transport ofchemical constituents in environmentalmedia.

a. ME Risk Reduction. MEI risk wasbased on exposure to the risk-drivingconstituents. Concentrations of the risk-driving constituents in the wasteleachate were selected randomly fromthe constituents' concentrationdistributions. A dilution-attenuationfactor (DAF), derived from EPA'ssubsurface fate and transport model(EPACML), was then randomly selectedand used to model the fate and transportof the constituents in ground water. (TheDAFs were developed using data fromthe Municipal Landfill Survey on landfillsize, hydrogeology, and distance fromthe unit to the closest drinking waterwell; see section III.E for furtherdiscussion of the model.) By dividing theinitial leachate concentrations of theisk-driving constituents by the DAF,exposure concentrations at a down-gradient well were estimated. Risksfrom ingestion of contaminated groundwater were then calculated. Thecarcinogenic MEI risk was expressed asthe probability of the ME1 contractingcancer over a 70-year lifetime, and thenon-carcinogenic MEl risk wasexpressed as an exceedance of thehealth-effects threshold.

Risk estimates were developed in thisway for baseline conditions and for the

final rule. The difference between thefinal rule and baseline risk estimatpyielded the MEI risk reduction (orbenefit).

EPA conducted a separate screeninganalysis of baseline MEI risks due to airemissions from surface impoundmentsin order to assess whether potential airrisks were significant. This was done byassuming that constituents inwastewaters would potentiallyvolatilize to the air rather than leach toground water. EPA's Liner LocationModel (Ref. 32) was used to estimateconcentrations of constituents at anexposure point 200 meters from the edgeof the surface impoundment. Bothcarcinogenic and non-carcinogenic riskswere estimated.

b. Population Risk Reduction.Population risk was estimated in muchthe same way as MEI risk, with theexception that ground water plumeareas for risk-driving constituents wereused to model the exposure bfpopulations located downgradient fromunits. The plume areas were developedfor a representative hydrogeologicenvironment, based on data from theMunicipal Landfill Survey.

Each plume area contained a gradientof exposure concentrations, with thehighest concentration near the unitboundary and the lowest concentrationnear the outside edge of the plume. Byassuming a uniform population densityof 1.6 persons per acre, based on theMunicipal Landfill Survey, it waspossible to estimate the number ofpersons exposed to each of theconcentration levels within each plume.

The population risk for thecarcinogenic constituent, based on theconstituent's risk-specific dose (RSD),was expressed as the number of cancercases over a 70-year lifetime. Thepopulation risk for the non-carcinogenicconstituent, based on the constituent'sreference dose (RfD), was expressed asthe number of persons exposed toaverage daily concentrations exceedingthe RfD over a 70-year period.

2. Resource Damage Avoided

Resource damage measures the costassociated with replacing contaminatedground water that had been used as asource of drinking water. Resourcedamage was assumed to result from anycontamination of ground water whichwould render it unsuitable for humanconsumption; other potential foregoneuses, such as industrial or agriculturaluses, were not addressed.

If the concentration of a constituent inground water exceeded a maximumcontaminant level (MCL}, the groundwater was assumed to be damaged. If


Federal Register I Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

the contaminant did not have an MCLbut the concentration exceeded a tasteand odor threshold or a health effectsthreshold, the ground water was alsoassumed to, be damaged. Areas ofdamaged ground water were derivedbased on a comparison of theconstituent's concentration within theplume with the constituent's MCL, tasteand odor threshold, or health-basednumber, in an approach similar to thatused to estimate plume areas forpopulation risk.

To place a value on the damagedresource, EPA assumed that analternative water supply system wouldhave to be built to provide water topersons living above. the area of thedamaged ground water. The costs ofconstructing the water supply systemincluded capital and O&M costs; thesecosts were discounted to the present ata rate of three percent to obtain theresource damage per facility. Additionof resource damage across facilitiesprovided a national estimate.

3. Cleanup Costs AvoidedAs an alternative measure of benefits,

EPA estimated the cleanup costsavoided as a result of the TC rule. Costsof cleanup of contaminated groundwater were estimated by assuming thatsites with resource damage in thebaseline would eventually requirecleanups. To develop an upper boundestimate, it was assumed that sites with.resource damage greater than $1,000,000(present valuel would require cleanup.

Cleanup costs were based on anaverage cost of $15 million per site, withcleanups beginning in 15 years. EPAestimated the average cost of cleanupby examining recent Superfund recordsof decision (RODs) for sitescontaminated with TC constituents thatrequired substantial ground watercleanup efforts. Costs were discountedto present values using a discount rateof three percent.

e. Used OffMethodology. EPAaddressed the impacts of the TG on usedoil separately from other wastes forseveral reasons. First, used oil isgenerated across a wide variety ofindustrial sectors. Second. unlike otherwastes, it has economic value and canbe sold in intermediate or end-usemarkets;. this complicates any analysisof the costs of regulating it as- ahazardous waste. Also. data on used oilare quite limited. Finally it is difficult toaccurately estimate quantities of usedoil that may exhibit the TC because inpractice TCLP filtration is sample-specific and difficult to predict.

The analysis of costs, economicimpacts, and benefits associated withused oi was qualitative in nature;, no

attempt was made to develop nationalestimates. In determining the quantity ofused oil potentially affected, EPAexcluded used oil that was: (1) Alreadyhazardous because it exhibits ahazardous waste characteristic (e.g.,ignitability); (2) recycled; or (3)generated by' "do-it-yourselfers" (i.e.,auto owners disposing of crankcase oil).In order to develop worst-case estimatesof impacts on used oil, it was assumedthat used oilwould filter in the TCLP. Itwas also assumed. that the facilitiesmanaging, used oil were subtitle Dfacilities. Finally, estimated impacts onused oil did. not account for the possiblestigma associated with management ofused oil as a hazardous waste.

4. Results

Results of the RIA are presentedbelow. These results are approximationsthat are intended to identify the mostsignificant impacts of the TC rule. Asdiscussed previously, there were. nodata on- the waste types and quantitiesgenerated by specific facilities in the,different industrial sectors. Therefore,EPA used more aggregated data andfocused on those, industrial sectorswhich were most likely to generatesignificant quantities of TC wastes.

a. Affected Wastes and Facilities.EPA estimated the amount of waste and,the number of facilities that would be"affected" by the rule, i.e., that wouldincur any incremental costs due torequired changes in managementpractices, for newly hazardous wastes.

1. Affected Wastes

The overall quantity of waste affectedby the TC was driven by wastewaters.EPA estimated the quantity of affectedwastewaters to be approximately 730million metric, tons (MMT1 per year andthe quantity of affected non-wastewaters (sludges and solids)i wouldrange from approximately 0.85 MMT[year to, 1.8 MMT/year. It should benoted that the affected wastewaters,which would be hazardous wastes, areassumed to be exempt from subtitle Cregulation in the post-regulatoryscenario due to their management inexempt tanks. However they would. beaffected wastes because a change inmanagement practice (from surfaceimpoundments to tanks)'would berequired.

The industrial sectors with the largestquantities of affected wastewaters werePetroleum Refining (SIC 2911), OrganicChemicals (SIC 286). Synthetic Rubber(SIC 2822), and Cellulosic and Non-Cellulosic Synthetic Fibers (SICs 2823and 2824). For the lower bound estimateof 0.85 MMT[year of non-wastewatermaffected, the sectors with the largest

quantities of affected non-wastewaterswere Pulp and Paper (SIC 26), SyntheticFiberi, Organic Chemicals, andPharmaceuticals (SIC 283). For the upperbound estimate of 1.8 MMT/year,industry sectors generating the largestquantities of affected non-wastewaterswere Petroleum Refining, Pulp andPaper, Synthetic Fibers, OrganicChemicals, and Wholesale PetroleumMarketing (SIC 517). Certain sectorsgenerate significant quantities of bothwastewaters and non-wastewaters dueto the wastewater treatment sludgesassociated with wastewater streams.Most of the affected wastewaters andnon-wastewaters are believed to begenerated by large facilities.

A total of twelve constituents.appeared as "cost-driving" constituentsin the analysis'. H-owever, benzene wasthe driving constituent for over 60percent of the affected waste quantity.Other volume-driving constituentsinclude chloroform (25%),. vinyl chloride(17%), and trichloroethylene (15%),.

2. Affected' Facilities

EPA estimated that between 15,000and 17.000 generators would be affectedby the rule. Costs and additionalrequirements: among these affectedfacilities will vary (e.g., some mayalready be RCRA generators or TSDFs,,others may need. to apply for RCRApermits or send wastes off-site). Over 90percent of these were small facilities(with fewer than 50 employees).. Theindustries with the most affected largefacilities were Hosiery arid Knit FabricFinishing (SIC 225). WholesalePetroleum, Marketing; OrganicChemicals, Petroleum Refining, andPlastics Materials and Resins (SIC 2821).The industries: with the most affectedsmall facilities were WholesalePetroleum Marketing, Hosiery' and KnitFabric Finishing MiscellaneousPetroleum and Coal Products (SIC 2992,Organic Chemicals, and PlasticsMaterials and Resins.

3. Sensitivity Analysis of AffectedWastes and Facilities

Changes in certain analyticalassumptions had significant effects onthe quantity of waste and number of'facilities affected by the TC final. rule.(Refer to section VI.B.3.a for discussionof the sensitivity analyses which wereconducted.) Some of the changes alsoaffected, cost and benefit results, asdiscussed below under cost results, andbenefit results.

Assuming that oily wastes would notfilter in the TCLP rather than assumingthat they would, would have a verysignificant effect on the quantity of non-

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wastewaters affected by the TC. Thiseffect can be seen in the differencebetween lower bound (assuming oilywastes do not filter) and upper bound(assuming oily wastes filter withoutcomplications) estimates of affectedquantities of non-wastewaters. Nearlyall of the non-wastewaters fromPetroleum Refining (including a verylarge-volume primary treatment sludge),Wholesale Petroleum Marketing, andPetroleum Pipelines are oily wastes.

Assuming that all wastewaters weremanaged in surface impoundments,rather than some portion being managedby practices exempt under subtitle C,increased affected wastewater quantitysignificantly to approximately 1,900MMT/year. It also increased the numberof facilities affected in certain sectors.

Finally, assuming that only 10 percentof the facilities would be affected for awaste failing the TC, rather than usingthe percent of the waste failing,significantly reduced the number offacilities affected by the TC in mostindustrial sectors.

b. Cost Results--1. Social Costs andCompliance Costs. EPA estimated thetotal social costs of the TC rule(excluding taxes and above-averageprofits) to be approximately $90 millionto $310 million per year (present value$1.3 billion to $5.7 billion); this does notinclude costs associated with used oil.Compliance costs (which include taxesand above-average profits) ranged from$130 million to $400 million per year(present value $1.9 billion to $6.0billion). While affected waste quantitieswere driven by wastewaters,compliance costs (for the scenariowhere oily wastes fail the TC and nosurface impoundment closure costs areincurred) were driven by non- "wastewaters due to the significantlyhigher incremental costs of managingnon-wastewaters. Non-wastewatersaccounted for over 95 percent ofcompliance costs.

For the lower bound cost estimate, theindustrial sectors with the largestcompliance costs were Pulp and Paper,Synthetic Fibers, Organic Chemicals,and Synthetic Rubber. For the upperbound cost estimate, the industrialsectors with the largest compliancecosts were Petroleum Refining, Pulp andPaper, Synthetic Fibers, Wholesale

-Petroleum Marketing, and OrganicChemicals. Constituents driving the costresults were: benzene, chloroform,trichloroethylene, vinyl chloride, andcarbon tetrachloride.

Approximately 90 percent of thecompliance costs (for the scenariowhere oily wastes fail the TC and nosurface impoundment closure costs areincurred) were incurred by large

facilities and 10 percent by smallfacilities across industrial sectors. Arelatively small number of largefacilities incurs the majority ofcompliance costs because large facilitiesare believed to have much greater wastegeneration rates than'small facilities.

The estimated number of subtitle Dfacilities seeking permits to become non-commercial subtitle C TSDFs was 40 to250; this does not include facilitiesseeking permits for storage or treatmentonly. Most of the expected permitapplicants were in the Pulp and PaperIndustry in the lower bound estimate.Most of these new TSDFs in, the upperbound estimate were in PetroleumRefining.

The number of existing subtitle C non-commercial TSDFs expected to seekpermit modifications to handle TCwastes was between 45 and 220,depending on Whether permits areconsidered for only disposal or fortreatment, storage, and disposal. Most ofthese facilities in the upper boundestimate were in the WholesalePetioleum Marketing and PetroleumRefining industries.

The number of subtitle C commercialTSDFs (SIC 4953) seeking permitmodifications or changes to interimstatus could be as high as 360, theestimated number of existingcommercial TSDFs. Many of thesecommercial TSDFs are primarily storagefacilities.

In addition, the TC rule would resultin as many as 15,000 new subtitle Cgenerators. Most of the new generatorswould be in Wholesale PetroleumMarketing and Hosiery and Knit FabricFinishing.

2. Sensitivity Analysis of Costs.Changes in certain analyticalassumptions had significant effects onthe social costs and compliance costs ofthe TC final rule. (Refer to sectionVI.B.3.a for discussion of the sensitivityanalyses which were conducted.) Someof the changes also affected benefitresults, as discussed below underbenefits results.

Assuming that oily wastes would notfilter in the TCLP, rather than assumingthat they would, would have asignificant effect on both social costsand compliance costs. The Agencyestimated, as a lower bound assumingthat no oily wastes will fail the TC test,social costs of about $90 million per yearand compliance costs of about $130million per year. By comparison, if itwere assumed for the purpose ofpredicting TCLP results that oily wastesbehave like other non-liquid wastes,social costs would be $190 million peryear and compliance costs would be$250 million per year.

Assuming that not all facilities wouldbe able to convert within six monthsfrom surface impoundments to tanks formanagement of their TC wastewatersrather than assuming that all facilitieswould be able to convert, significantlyincreased the cost of the rule. Based onlandfill closure of impoundments, thisassumption added approximately $120million to annual social costs and $140million to annual compliance costs.

Splitting wastestream quantity evenlybetween small and large facility sizecategories, rather than based on value ofshipments, shifted wastes from large tosmall facilities. While this did not affectthe overall costs greatly, it significantlydecreased compliance costs for largefacilities and increased them for smallfacilities.

Finally, assuming that only.10 percentof the facilities would be affected for awaste failing the TC, rather than usingthe percent of the waste failing,significantly reduced social costs andcompliance costs due to the largerquantities of waste being managed at asmaller number of facilities and theresultant economies of scale. Theestimated number of new subtitle CTSDFs, existing TSDFs seeking permitmodifications, and new subtitle Cgenerators also decreased significantly.

c. Economic Impact Results-.Significantly Affected Facilities. Basedon the economic impact criteriadiscussed previously the estimated totalnumber of significantly affectedfacilities was 65 to 81, of which most (51to 66) are large. The fact that most of thesignificantly affected facilities are largecan be partially explained by the factthat data indicate there are no smallfacilities in certain sectors (e.g.,Cellulosic Synthetic Fibers). Anotherreason for the preponderance ofsignificantly affected large facilities isthat for some Wastes, total compliancecosts are less for small facilities than forlarge facilities because large facilitiesare believed to generate significantlymore waste.

In the lower bound estimates,significantly affected facilities wereexpected in four industrial sectors: Pulpand Paper, Synthetic Rubber, SyntheticFibers, and Organic Chemicals. In thelower bound estimates the Pulp andPaper industry was predicted to havethe greatest number of significantlyaffected facilities (35), of which 30 arelarge facilities. The synthetic rubberindustry had the highest number ofsignificantly affected small facilities (8),out of a total of 14 significantly affectedsmall facilities. None of the industriesexamined were expected to sufferfacility closures as a result of the TC.



In the upper bound estimates,significantly affected facilities wereexpected in seven industries: Puhn andPaper, Synthetic Rubber, SyntheticFibers, Organic Chemicals, Textiles,Pharmaceuticals, and Plastics andResins. Pulp and paper had the largestnumber of significantly affectedfacilities-36 out of 80 for all facilities.

2. Effects on Product and CapitalMarkets

The industries with significantlyaffected facilities have very littlepotential to pass compliance costs on toconsumers in the form of higher prices.These industries produce primarilyintermediate goods (e.g., rubber, paper,fibers, and chemicals}'which are used ina number of subsequent processes (e.g.,manufacturing and fabrication) beforethey reach consumer markets. The usersof these intermediate products haveaccess to similar or identical productsfrom U.S. suppliers that are notsignificantly affected by the TC andfrom foreign suppliers; becausesubstitutes are available, these userswould not be forced to pay higher pricesfor the intermediate products.

While results suggest that prices inproduct markets will not be affected, atleast some impact is likely on capitalmarkets. Because affected facilities willnot be able to. pass compliance coststhrough to buyers in the form of higherprices, they will experience lowerprofits. Lower profits will reduce thevalue of capital tied up in thesefacilities. However, as most of theaffected facilities are part of integratedproduction systems and are owned bylarge firms with significant assetholdings, the effect on capital markets(i.e., stock prices and bond ratings),should be relatively small.

3. Sensitivity Analysis of EconomicImpacts.

A change in one of the analyticalassumptions had significant effects oneconomic impacts due to the TC finalrule. Refer to sectiod VI.B.3.a fordiscussion of the sensitivity analyseswhich were conducted.

Splitting wastestream quantity evenlybetween small and large facility sizecategories, rather than based on value ofshipments, shifted' wastes from large tosmall facilities. Under the scenariowhere oily wastes fail the TC and nosurface impoundment closure costs areincurred, this resulted in nearly 40additional small facilities withsignificant economic impacts and 10small facility closures.

d. Benefits Results. EPA estimated thebenefits of regulating, TC wastes on awastestream by wastestream basis;

results of this analysis are presented inTable VI-3. As discussed in the benefitsmethodology section, results foidifferent benefit measures (humanhealth risk, resource damage, andcleanup costs avoided) are likely tooverlap and should not be added.

TABLE VI-3.-BENEFRTS OF THE TC RULE

Reduction in ME Risk:" Reduction in' Carcinogenic 370 to 780.

Risk (number of facilities withrisk greater than 1 x10E-5 atdown-gradient well).

" Reduction in Non-Carcinogenic 8.Risk (number of facilities withexposure above a health-basedthreshold at downgradient well).

Reduction in Population Risk:" Reduction in Carcinogenic 6.

Risk (number of cancer casesover 70 years);

" Reduction in Non-Carcinogenic 320.Risk (number of persons withexposure above a health-basedthreshold at downgradientwells).

Reduction in Resource Damage 3,800.(present value; millions of 1988dollars).

Cleanup Costs Avoided (present Up to 15,000.value, millions of 1988 dollars).

1. MEI Risk

As can be seen from the table, there isa potentially significant reduction underthe final rule in the carcinogenic risk tothe most exposed individual (MET).There are from 370-780 fewer facilitiesmanaging wastes that present risks tothe most exposed individual. (MEt)greater than, 1X 10E- 5 under the finalrule than there were under baselineconditions. The industrial sectorsdriving these benefits include WholesalePetroleum Marketing (SIC 517) andMiscellaneous Plastics Products (SIC3079). The constituent driving most of.these benefits is benzene. The differencebetween the. lower and upper boundsresults from certain oily wastes that areunregulated in the lower bound.

For non-carcinogenic MEI risk, thereare 8 fewer facilities managing.wastewaters where the exposure to anon-carcinogenic constituent exceedsthe reference dose (RfD)- under the finalrule than under baseline conditions.Wastes from Wholesale PetroleufMarketing drive these benefits results.Cresols are the risk-driving constituents.

The Wholesale Petroleum Marketingsector presents significant risks due tothe large number of facilities managingwastewaters and non-wastewaters. Thenumber of facilities in this sectorestimated to manage wastewaters andnon-wastewaters are 1,290 and 1,050facilities, respectively; this compareswith 1,900 and 8,600 facilities,respectively, managing affected

wastewaters and non-wastewatersacross all industrial sectors.

A screening analysis of MEl.risks dueto air emissions from surfaceimpoundments was conducted to gaugethe potential risk via the air medium.This analysis indicated that in sectorsother than Wholesale PetroleumMarketing approximately 20 percent ofmodeled facilities had carcinogenic risksgreater than 1x 10E - , and 5 percent hadnon-carcinogenic doses greater than theRfD; MEI air'risks from WholesalePetroleum Marketing, were less than1 x10E- . Benzene contribtted most ofthe carcinogenic risks while phenol wasresponsible for most of the non-carcinogenic risks.

The industries generating wastes withhigh MEl air risks differ to some extent.from those generating wastes with highMEl ground water risks. The industriesgenerating wastes with high MEI airrisks include Pulp and Paper, PlasticsMaterials and Resins,. Synthetic Rubber,Cellulosic and Non-Cellulosic SyntheticFibers (SICs 2823 and 2824],. and OrganicChemicals.

There is some potential overlap inestimates of air and ground water risk.The wastewater MEl risks via groundwater were based on the assumptionthat all the constituent mass wasavailable for leaching to ground water;in contrast, the air risks assumed somepercentage of constituent mass wouldvolatilize from impoundments. As aresult, the wastewater MEl risks viaground water are likely to be overstated.

2. Population Risk

Based on a very limited analysis ofpopulation risk, EPA estimates thatthere would be six fewer cancer casesover the 70-year modeling period due tothe final rule. Wholesale PetroleumMarketing (constituent: benzene) andPlastics. and Resins (SIC 2821)1(constituent: vinyl chloride) drive thesebenefits. The reduction in number ofpersons exposed to non-carcinogens atconcentrations greater than the RfDswas estimated to be 320 over a 70-yearperiod. Sawmills and Planing Mills (SIC2421) and Organic Chemicals(pentachlorophenol and methyl ethylkeytone) drive these, results.

3. Resource. Damage

The total reduction in- resourcedamage would be approximately $3.8billion (present value). WholesalePetroleum Marketing- and MiscellaneousPlastics Products are the industrialsectors- driving resource damagebenefits. Benzene is the drivingconstituent,

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4. Cleanup Costs Avoided

Estimated cleanup costs avoided dueto the final rule ranged up to $15 billion(present value). Under the assumptionthat all sites with significant resourcedamage (i.e., resource damagegreaterthan $1,000,000 (present value)) wouldrequire cleanup, approximately 1,600facilities would require cleanup.

5. Sensitivity Analysis of Benefits

Changes in certain analyticalassumptions had significant effects onthe benefits of the TC final rule. (Referto sections VI.B.3. a and d for discussionof the sensitivity analyses which wereconducted.) Some of the changes alsoaffected cost results, as discussed undercost results.

Assuming that oily wastes would notfilter in the TCLP, rather than assumingthat they would, would reduce thebenefits associated with non-wastewaters, as can be seen in thelower bound estimates indicated in theresults above. This would resultprimarily from the significant reductionin the number of facilities managingnon-wastewaters in WholesalePetroleum Marketing.

Assuming that all wastewaters weremanaged in surface impoundments,rather than some portion being managedby practices exempt under subtitle C,would increase the number of facilitiesaffected in many sectors and increasebenefits significantly. Benefits forwastewaters could increase byapproximately 10 times since therewould be 10 times as many facilitieswith surface impoundments.

Assuming that only 10 percent of thefacilities would be affected for a wastefailing the TC, rather than using thepercent of the waste failing, significantlyreduced the number of facilities affectedby the TC in all industrial sectors. Thiswould significantly reduce benefits as aresult, since fewer facilities would bemanaging wastes.

Assuming that all facilities havedown-gradient wells, rather thanassuming only 46% have down-gradientwells, would increase benefit results bya factor of approximately two.

e. Cost-Effectiveness. The Agencyestimated the cost-effectiveness of thefinalrule and of several regulatoryalternatives. This discussion ispresented in the regulatory impactanalysis document, which is part of thepublic docket for the rule.

f Used Oil Results. Used oil isgenerated across a wide variety ofindustrial sectors. Some generatorsmanage or dispose of their used oildirectly while others provide their usedoil to the used oil management system

(UOMS), a system of intermediatecollectors and processors (Ref. 33).Firms in the UOMS then re-refine orprocess the used oil and/or sell it forvarious end uses.

. Under the worst-case assumption thatused oil would not create TCLP filtrationproblems, EPA found based onconstituent concentration data (see Ref.8), that virtually all used oil would failthe TC. EPA determined that three end-use management practices for used oilwould be affected: landfilling/incineration, dumping, and road oiling.

Once used oil became TC hazardous,it would have to be shifted to other end-use management practices. Much of theused oil that is currently dumped orapplied directly to roads by generatorswould probably be collected and sold tothe UOMS. Firms in the UOMS thatcurrently sell used oil for road oilingwould generally shift this oil to othermanagement practices, such as re-refining or burning as a fuel. Used oilthat is managed by landfilling orincineration in subtitle D units wouldlikely be shifted to management insubtitle C units.

The shift in management practiceswould impose costs on used oilgenerators, the UOMS, and end-users ofused oil. Used oil generators currentlyproviding used oil to the UOMS wouldbe likely to pay somewhat highercollection costs due to pass-through ofcompliance costs by firms in the UOMS.Generators that currently manage theirwastes by road oiling would incurstorage and collection costs for theirused oil as well as costs for a road-oilingsubstitute. Generators directly managingtheir wastes by dumping would incurcosts for storage and collection. Firms inthe UOMS that sell used oil for roadoiling would be forced to sell the oil inless profitable markets, and some firmscould close if unable to enter anothermarket. Firms in the UOMS could alsoincur costs for disposal of low qualityused oil and related wastes in subtitle C(rather than subtitle D) units if thesewastes were TC hazardous; asdiscussed above, some of these costscould be passed on to used oilgenerators. Firms that re-refine used oilcould benefit from the TC rule, since agreater volume of used oil wouldpotentially be available at a lower price.Finally, end-users that purchase used oilfor road oiling would Incur costs for analternative dust suppressant.

The shift in management practicescould also result in certain benefits. Aprevious study of carcinogenic risksfrom used oil management practices(Ref. 34) indicates that dumping of usedoil may present significant risks relativeto other management practices (with the

possible exception of burning in boilers,where risks are more comparable). Roddoiling appears to present moresignificant risks than recycling andcomparable or fewer risks relative toburning in boilers or landfill disposal. Itis difficult to draw definitiveconclusions concerning benefits due tothe different constituent profiles andpopulation densities associated witheach of the management practices in therisk analysis.

C. Regulatory Flexibility Analysis

1. Approach

The Regulatory Flexibility Act (5U.S.C. 601 et seq.) requires thatwhenever an agency publishes a noticeof rulemaking, it must prepare aRegulatory Flexibility Analysis (RFA)that describes the effect of the rule onsmall entities (i.e., small businesses,small organizations, and smallgovernmental jurisdictions). An RFA isunnecessary, however, if the Agency'sadministrator certifies that the rule willnot have a significant economic effecton a substantial number of smallentities.

EPA examined the final rule'spotential effects on small entities asrequired by the Regulatory FlexibilityAct. Three measures, based on EPAguidelines for conducting an RFA, wereused to determine whether the rulewould have a "significant economiceffect" on small entities: the ratio ofcompliance cost to cost of production,the ratio of compliance cost to value ofsales, and the ratio of cash fromoperations to compliance cost (the lastratio being used to assess potentialclosures). Two of the three criteria, theratio of compliance cost to cost ofproduction and the ratio of cash fromoperations to compliance cost, arediscussed in section VI.B.3.c. The third,the ratio of compliance cost to value ofsales, was estimated for small and largefacilities; if the difference between theseratios was greater than ten percent, thisindicated a significant impact.

The guidelines for conducting RFAsare somewhat ambiguous with respectto evaluating impacts based on the thirdcriterion. Determining whether thedifference between ratios exceeds tenpercent can be done by subtracting thelarge facility ratio from the small facilityratio or by dividing the small facilityratio by the large facility ratio. Dividingthe small facility ratio by the largefacility ratio may incorrectly indicatesiqnificant impacts on small facilitieswhen both ratios are very small but thesmall facility ratio is larger than thelarge facility ratio. (For example. a small



facility ratio of 0.00002 divided by a,large facility ratio of 0.00001 wouldindicate a significant impact on smallbusinesses based on the divisionF pproach, despite the fact that the verylow ratio of compliance cost to value of.sales for small facilities indicates littleimpact on small facilities.) Therefore,the division approach must beinterpreted with caution.

A "substantial number" of smallentities was assumed to be 20 percent ormore of the population of smallbusinesses, small organizations, or smallgovernment jurisdictions within theuniverse of facilities affected by therule.

The Agency defined a small businessas a business employing 50 employeesor less. (Standard Small BusinessAdministration criterion is 500employees.) EPA decided to use the 50.employee definition of a small businessbecause the RIA estimates facility-levelimpacts, and the SBA definition appliesto entire firms. The SBA definitionwould designate most of the facilities inthe examined industries as smallbusinesses, which would obscuredifferential impacts on smaller facilities.

Impacts on small businesses related tocosts of compliance for used oil andcontaminated soils were not examineddue to lack of data on the facilitiesexperiencing those costs.

2. ResultsThe only entities found to be affected

by the final rule were small businesses,defined here as businesses employingfewer than 50 persons. No smallorganizations or small governmentjurisdictions were identified as potentialTC waste generators in the TC industrystudies which form the foundation forthis analysis.

The Agency did ftot identify anyindustries in which 20 percent or moreof the small businesses weresignificantly affected based on the ratioof compliance cost to cost of production,the ratio of cash from operations tocompliance cost, or the ratio ofcompliance cost to value of sales (usingthe subtraction approach). Using thedivision approach for the ratio ofcompliance cost to value of salesindicated that small businesses in foursectors (including Pulp and Paper,Synthetic Rubber, Organic Chemicals,and Wholesale Petroleum Marketing)would be significantly affected.However, since the small facility andlarge facility ratios were both quitesmall (small facility ratios were lessthan 0.03), the Agency does not expectsignificant small business impacts inthese sectors. Based on these results,EPA has concluded that today's final

rule will not have a significant effect ona substantial number of small entities.As a result of this finding, EPA has notprepared a formal RFA in support of therule. More detailed information on smallbusiness impacts is available in the RIAfor this rule.

D. Response to Comments on RIA forJune 13, 1986 Proposal

-EPA received many comments on theRIA for the proposed TC rule. Thissection presents a general summary andanalysis of the public commentsconcerning the original RIA; all of thecomments are addressed in thebackground document for this final rule.Major issues addressed by commentersincluded consideration of particularindustries, specific aspects of cost andbenefit methodologies, cost and benefitestimates, and the assessment of smallbusiness impacts.

1. Industries Included in the Analysis

The majority of comments on the RIAfor the proposed rule concerned theabsence of specific industrial sectorsfrom the group examined for potentialimpacts. Other commenters criticizedthe RIA for not considering the effects ofthe TC on end users of products and onfacilities such as Publicly OwnedTreatment Works and MunicipalLandfills.

Industries that commenters suggestedshould have been evaluated includednatural gas production, manufacturing ofa variety of products, including forestproducts, pharmaceuticals, automobiles,plastics, metals, polyvinyl chloride,semi-conductors, wire and cables, andwaste management. The Agency agreeswith commenters that a number ofindustrial sectors were not addressed inthe RIA for the proposed rule. TheAgency notes, however, that several ofthe wastestreams that commentersbelieved should have been included inthe RIA (based upon the proposedregulatory levels) are not expected to bedefined as hazardous based upon thefinal regulatory levels beingpromulgated today. One of thefundamental problems with determiningwhich industries would potentially beaffected by the TC is lack of data oncurrently non-hazardous wastes. Sincethese wastes are currently outside thesubtitle C system, requirements forinformation gathering related to themare minimal.

The Agency made extensive efforts, inpreparing the RIA for the TC final rule,to obtain data on the industrial sectorspotentially affected by the TC. Thesedata were derived from a variety ofsources. The Agency contactednumerous trade associations and

individual facilities and collectedpertinent EPA and other governmentpublications. In addition, EPA prepareda series of TC industry study reports onthose sectors most likely to generatesignificant quantities of TC wastes.

In preparing its TC industry studies,EPA first conducted preliminary studieswhich examined a large number ofindustries, with emphasis on identifyingwhether or not TC constituents wouldbe likely to be present in industrywastes. Based on the preliminarystudies, EPA completed detailed profilesof potentially affected industries for usein the final RIA. The Agency examinedthe potential for impacts on a number ofindustries that were not considered inthe RIA for the proposed rule, as well asreconsidering some that were addressedin that RIA. Table VI-1 in section VI.Bcompares the coverage of industries forboth the proposed rule RIA and the finalrule RIA and indicates the industries forwhich detailed quantitative analysiswas conducted.

Commenters also criticized theproposed rule RIA for not consideringeffects on end-users of productscontaining TC constituents. Examples ofsuch end-user industries includeagricultural chemical users, transporters,automotive maintenance facilities,petroleum retailers, medical facilities,and research laboratories. The Agencyrecognizes that TC toxicants exist in avariety of substances, and that end-users as well as producers of productscontaining TC constituents could beaffected by the rule. Some end-users notidentified in the RIA may be affected,but there is no information to quantifythese potential impacts. The Agencybelieves that some of the impacts onaffected end users may be mitigated bysmall quantity generator regulationsunder 40 CFR 261.5.

Finally, several commentersquestioned EPA's assessment of impactson Publicly Owned Treatment Works(POTWs), resourbe recovery facilities,public water suppliers, municipallandfills, the electrical services industry,and currently regulated RCRA facilities.As discussed previously in sectionlII.K.2, the Agency has tested a numberof POTW sludges to determine whetheror not these sludges would beconsidered hazardous under the TC; thedata generally indicate that thesewastes would not be affected by the TC(Ref. 8). Because the final regulatorylevel for chloroform is significantlyhigher than originally proposed, EPAbelieves that public water suppliers alsoare unlikely to generate TC wastes. TheAgency analyzed wastestreamsgenerated by the Electrical Services

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industry. These wastes were excludedfrom the RIA because they are fossil fuelcombustion wastes, which are exemptfrom subtitle C regulation until adetermination is made as to whetherthey should be regulated as hazardous.The Agency acknowledges that somewaste generated by waste managementfacilities may exhibit the TC; however,most of these wastestreams thatcommenters believed should be includedare not expected to exhibit the TC underthe final regulatory levels. Finally,impacts on currently regulated RCRAfacilities (in the industries included inthe RIA) were addressed in the RIA.

2. Estimation of Costs and EconomicImpacts

Many commenters expressed concernthat the compliance cost estimates forfacilities included in the economicimpact analysis did not capture many ofthe expenditures faced by handlers ofhazardous waste. The most commoncriticism was directed at the omission ofthe cost for actually performing theTCLP. Other commenters mentionedinsurance costs and costs associatedwith RCRA permit applications. Anotherlarge group of comments concerned thecosts for permitting and retrofitting thelarge universe of surface impoundmentscontaining wastewaters which wouldexhibit the TC. In addition, a number ofcommenters contended that the RIAsignificantly underestimated potentialeconomic impacts of the TC.

Other commenters claimed that theexpense of the highly sophisticatedequipment and specially trainedpersonnel necessary for the testing ofwastes would pose a significant. burdenon many firms, especially those withouton-site laboratory facilities. The Agencyrecognizes that testing of wastes couldpose a significant expense for firms thatchoose to test their wastes. On the otherhand, there is currently no RCRArequirement for generators to test theirwastes; the determination ofhazardousness may be made based oneither laboratory analysis of the wasteor on knowledge of the waste, rawmaterials, and production processes.The Agency expects that manygenerators will rely on the lattermethod, and elect not to perform theTCLP. The Agency is still consideringpromulgating a testing requirement at afuture date. If a testing requirement isproposed, potential costs of testing willbe analyzed in detail.'

Recognizing that administrative andinsbrance costs can constitute asignificant portion of waste managementcosts, the Agency considered these incost estimates in the final RIA. Inaddition, the !ost of preparing RCRA

permit applications is considered in thecost of subtitle C waste management, asare items such as liability insurance,personnel training, and contingencyplanning.

In response to comments that surfaceimpoundment impacts were understated,the Agency examined the effect of theTC rule on wastewaters andestimatedthe costs of compliance with subtitle Crequirements. The Agency assumed inthe final RIA that, based on least-costmanagement practices, surfaceimpoundments would not have to be'retrofitted. Instead, it was assumed thataffected wastewaters would besegregated and treated in a separatetank system, while remaining non-hazardous wastewaters could continueto be managed in the impoundments. Inderiving an upper bound estimate ofcosts, it was assumed that someimpoundments would have to undergosubtitle C clean closure.

Given the broad scope of the TC ruleand the general lack of data onindustries and facilities managingcurrently non-hazardous wastes, theAgency agrees that economic impactson certain sectors may have beenunderestimated in the RIA for theproposed rule. As discussed above, theAgency has made significant efforts inthe final RIA to more accuratelycharacterize the sectors potentiallyaffected by the TC and to estimate theactual impacts on affected facilities.

3. Estimation of Benefits

Several commenters remarked on theoriginal methodology used for theestimation of benefits. The mostfrequent target of criticism was theassumption that all contaminatedaquifers would be cleaned up as a resultof the TC. Commenters also questionedthe validity of assuming that groundwater resource conditions in NorthCarolina were representative ofconditions across the entire UnitedStates.

Commenters on the use of aquifercleanup as the basis for estimatingbenefits of the proposed rule asked forjustification of the assumption that allaquifers would be cleaned up and anexplanation of the benefits to humanhealthand the environment whichwould result from the cleanup. TheAgency used a different methodology toestimate benefits for the finalRIA thanwas used for the original RIA. For thefinal RIA, EPA examined three potentialtypes of benefits: human health riskreduction, resource damage avoided,and cleanup costs avoided. Theassumption that all aquifers would becleaned up was not used in the finalRIA. In estimating benefits based on

cleanup costs avoided throughcontrolled subtitle C management of TCwastes, EPA assumed in the RIA for thefinal rule that, for the near term, thesubtitle D facilities with-down-gradientwells and with at least some resourcedamage (as predicted by the resourcedamage analysis) would be the mostlikely candidates for cleanup.

The Agency agrees with the commentsthat ground water resource conditions inNorth Carolina may not berepresentative of conditions across theentire United States. As a result, in thefinal RIA EPA used distributions ofhydrogeologic parameters which wererepresentative of nationwide conditions,rather than relying on hydrogeologicinformation from one state.

4. Cost-Benefit Comparisons

In general, commenters argued thatthe RIA overestimated likely benefits ofthe proposed rule while underestimatingthe potential impacts. Commentersbelieved that the TC would bring largequantities of waste into the subtitle Csystem with little or no attendantenvironmental or health benefit. One.commenter claimed that, after all-indirect impacts are considered, the netbenefits of the rule could be negative.Another commenter, however, statedthat benefits were actuallyunderestimated because of assumptionsin the baseline scenario.

The Agency has used an improvedmethodology and additional data.in thefinal RIA. EPA believes that the finalRIA provides reasonable estimates ofthe potential costs and benefits of therule. As presented in this section, thefinal RIA does indicate that the TC willbring relatively large quantities of wasteinto the subtitle C system, and alsoindicates that there will be attendantbenefits. The Agency.used cost andbenefit estimates to compare relativecosts and benefits of the variousregulatory options. The analyses wereconducted separately using approachesconstructed to make the best possibleuse of available data. The separateanalyses were not meant to be used toproduce absolute measures of costeffectiveness. The RIA containsdiscussion of the Agency's evaluationand comparison of cost and benefitresults.

5. Small Business Analysis

The Agency received many commentson its assessment of the effects of theproposed TC on small businesses. Onegroup of comments focused on thedefinition chosen by EPA for smallbusinesses. The Agency was alsocriticized for its threshold for



determining if a "substantial number" ofsmall businesses would suffersignificant economic impacts, andtherefore necessitate the preparation ofa full Regulatory Flexibility Analysis.Finally, many commenters felt that theanalysis severely underestimated theimpact of the rule on small businesses.

Commenters asked why the Agencydid not use the standard Small BusinessAdministration (SBA) criterion of 500employees to define a small business.The Agency decided to use the 50employee definition of a small businessbecause the RIA estimates facility-levelimpacts, and the SBA definition appliesto entire firms. In the absence of data toestimate firm-level impacts, the Agencychose the 50 employee cutoff as anappropriate small facility definition forthe RIA. The SBA definition woulddesignate most of the establishments inmost of the examined industries assmall facilities, which would obscuredifferential impacts on smaller facilities.

The Agency was criticized for using a20 percent threshold for determining if a"substantial number" of smallbusinesses would be significantlyaffected. Commenters claimed that itwas arbitrary to consider the smallbusiness impact negligible if "only 19.9percent" of small business weresignificantly affected. The Agencyrecognizes that, for an individualfacility, the magnitude of impacts is not'altered by the number of other facilitieswhich are significantly affected.Nevertheless, the Agency believes that20 percent is a reasonable benchmarkfor defining a "substantial number" ofsmall businesses. The 20 percentthreshold is commonly applied in RIAsconducted by EPA.

A large number of commenterscriticized the overall conclusions of thesmall business analysis, declaring thatthe analysis severely underestimatedthe economic effects of the TC on smallbusinesses. Commenters maintainedthat the universe of small businesseswas inadequately addressed. Examplesof small businesses not included in theanalyiis which commenters felt shouldhave been considered included servicestations and vehicle maintenancefacilities. Commenters also mentionedthe expense of performing the TCLP,claiming that it was an especiallysignificant hardship for smallbusinesses.

As explained in the general discussionof the industrial sectors included in theRIA, the Agency made extensive effortsto identify and include sectorspotentially affected by the TC rule,including end users of products. And, asdiscussed under the comments onincorporating testing costs, these costs

were not included since generators arenot currently required to test theirwastes. Although EPA maintains that afull RFA is not necessary for the TCrule, it realizes that the impact of therule could be significant for individualsmall enterprises.

E. Paperwork Reduction Act

The information collectionrequirements in this rule have beenapproved by the Office of Managementand Budget (OMB) under the PaperReduction Act, 44 U.S.C. 3501 et seq.,and have been assigned the followingOMB control numbers: 2050-0007, LandDisposal Permitting Standards; 2050-0008, RCRA Closure/Post-Closure; 2050-0009, Hazardous Waste Storage andTreatment Facilities; 2050-0011,Contingency Plans for Hazardous WasteFacilitiis; 2050-0012, General FacilityOperating Requirements; 2050-0013,Operating Record for Hazardous WasteFacilities; 2050-0028, Notification of aHazardous Waste Activity; 2050-0033,Reporting, Recordkeeping, and Planningfor Ground-Water Monitoring; 2050-0034, RCRA Hazardous Waste PermitApplication Part A; 2050-0036, RCRAFinancial Assurance Requirements;2050-0037, Recordkeeping and Reportingfor RCRA Permitees; and 2050-0039,Uniform Hazardous Waste Manifest forGenerators and Transporters.

VII. References1. U.S. EPA, "Response to Public Comments

Background Document for the SubsurfaceFate and Transport Model Used in theToxicity Characteristic Rule", 1990.

2. U.S. EPA, "Response to CommentsBackground Document for the ToxicityCharacteristic", 1989.

3. U.S. EPA, "Technical and Response toComments Background Document forChronic Toxicity Reference Levels",1990.

4. U.S. EPA, "Technical and Response toComments Background Document for theTCLP (Method 1311)", 1989.

5. U.S. EPA, "State Subtitle D Regulations onSolid Waste Landfills", Final Volume I,1986.

6. U.S. EPA, "National Survey of Solid Waste(Municipal) Landfill Facilities", FinalReport, EPA/530-SW-88-034, 1988.

7. U.S. EPA, "Summary of Data on IndustrialNon-hazardous Waste DisposalPractices", Final Report, December 1985.

8. U.S. EPA, "Toxicity CharacteristicRegulatory Impact Analysis", 1989.

9. U.S. EPA, "Background Document forEPA's Composite Landfill Model(EPACML)", 1990.

10. Simkins, S. and M. Alexander, "Modelsfor Mineralization Kinetics with theVariables of Substrate Concentrationand Population Density", "Applied andEnvironmental Microbiology", 1984, Vol.47, No. 6. pp. 1299-1306.

11. Lewis, D. L. and D. K. Gattie. "Predictionof Substrate Removal Rates of AttachedMicroorganisms and of relativeContributions of Attached andSuspended Communities at Field Sites","Applied and EnvironmentalMicrobiology", 1988, Vol. 54, No. 2, pp.434-440.

12. Robinson, J. A. and W. C. Characklis."Simultaneous Estimation of Vmax, Kma,and the Rate of Endogenous SubstrateProduction (R) from Substrate DepletionData", "Microbial Ecology, 1984, Vol. 10,pp. 165-178.

13. Karickhoff, S. W. "Chapter 11: SorptionKinetics of Hydrophobic Pollutants inNatural Sediments", "Contamina'nts andSediments, Vol. 2: Fate and Transport,Case Studies, Modeling, Toxicity, AnnArbor Science Publishers, Inc. AnnArbor, Michigan, 1980. pp. 193-205.

14. Kohring, C., 1. E. Rogers and J. Wiegel."Anaerobic Biodegradation of 2,4-Dichlorophenol in Freshwater LakeSediments at Different Temperatures"."Applied and EnvironmentalMicrobiology", 1989, Vol. 55, No. 2, pp.348-353.

15. Hwang, H., R. E. Hodson, and D. L. Lewis."Assessing Interactions of OrganicCompounds During Biodegradation ofComplex Waste Mixtures by NaturallyOccurring Bacterial Assemblages","Environmental Toxicology andChemistry", 1989, Vol. 8, pp. 209-214.

16. U.S. EPA, "Screening Survey of IndustrialSubtitle D Establishments", Draft FinalReport, December 1987.

17. U.S. EPA, "Analysis of U.S. MunicipalWaste Combustion Operating Practices",May 1989.

18. U.S. EPA, "Cooperative Testing ofMunicipal Sewage Sludges by theToxicity Characteristic LeachingProcedure and Compositional Analysis",Draft Final, 1988.

19. U.S. EPA, "Estimates of Waste Generationby Cellulosic'Manmade Fibers, SyntheticOrganic Fibers, Petroleum Refining,Rubber and Miscellaneous PlasticProducts, Leather Tanning and Finishing,Oil and Gas Transportation Industries,and the Laundry, Cleaning and GarmentServices", May 27, 1987.

20. U.S. EPA, "Estimates of Waste Generationby the Lumber and Wood ProductsIndustry", December 9, 1987.

21. U.S. EPA, "Estimates of Waste Generationby-the Organic Chemical Industry",December 1987.

22. U.S. EPA, "Estimates of Waste Generationby Petroleum Crude Oil and PetroleumProducts Distribution and WholesaleSystems", November 13, 1987.

23. U.S. EPA, "Estimates of Waste Generationby Plastic Materials and Resins",November 1987.

24. U.S. EPA, "Estimates of Waste Generationby the Petroleum Refining Industry",November 13, 1987.

25. U.S. EPA, "Estimates of Waste Generationby the Pharmaceutical Industry",November 16, 1987.

11861



26. U.S. EPA, "Estimates of Waste Generationby the Pulp and Paper Industry". August12, 1987.

27. U.S. EPA, "Estimates of Waste Generationby the Synthetic Fibers Industry",November 18, 1987.

28. U.S. EPA, "Estimates of Waste Generationby Textile Mills", December 15, 1987.

29. U.S. EPA, "Synthetic Rubber Industry",November 1987.

30. U.S. EPA, "Wastewater TreatmentProfiles for Industrial Sectors Impactedby Proposed Toxicity Characteristic",August 19, 1988.

31. U.S. EPA, "Wastewater TreatmentProfiles for Industrial Sectors Impactedby Proposed Toxicity Characteristic",August 24, 1988.

32. U.S. EPA, "Liner Location Risk and CostAnalysis Model, Phase II", Draft Report,1986.

33. U.S. EPA, "Composition and Managementof Used Oil Generated in the UnitedStates", September 1984.

34. U.S. EPA, "Risk Assessment of ProposedWaste Oil Standards for theManagement of Used Oil", August 1985.

List of Subjects in 40 CFR Parts 261, 264,265, 268, 271, and 302

Administrative practice andprocedure, Air pollution control,Chemicals, Confidential businessinformation, Hazardous materialstransportation, Hazardous substances,Hazardous waste, Indian lands,Intergovernmental relations, Naturalresources, Nuclear materials, Penalties,Pesticides and pests, Radioactivematerials, Recycling, Reporting andrecordkeeping requirements, Superfund,Water pollution control, Water supply,Waste treatment and disposal.

Dated: March 5,1990.William K. Reilly,Administrotor.

For the reasons set out in thepreamble, Chapter I of Title 40 of theCode of Federal Regulations is amendedas follows:

PART 261-IDENTIFICATION ANDLISTING OF HAZARDOUS WASTE

1. The authority citation for part 261continues to read as follows:

Authority: 42 U.S.C. 6905, 6912(a), 6921, and6922.

2. Section 261.4 is-amended byrevising paragraphs (b)(6](i)introductory text, and (b)(9) and byadding paragraph (b)(10) to read asfollows:

§ 261.4 Exclusions.

(b) * * *

(6)(i) Wastes which fail the test for theToxicity Characteristic becausechromium is present or are listed in

subpart D due to the presence ofchromium, which do not fail the test forthe Toxicity Characteristic for any otherconstituent or are not listed due to thepresence of any other constituent, andwhich do not fail the test for any othercharacteristic, if it is shown by a wastegenerator or by waste generators that:

(9) Solid waste which consists ofdiscarded wood or wood productswhich fails the test for the ToxicityCharacteristic solely for arsenic andwhich is not a hazardous waste for anyother reason or reasons, if the waste isgenerated by persons who utilize thearsenical-treated wood and woodproducts for these materials' intendedend use.

(10) Petroleum-contaminated mediaand debris that fail the test for theToxicity Characteristic of § 261.24 andare subject to the corrective actionregulations under part 280 of thischapter.

3. Section 261.8 is added to subpart Ato read as follows:

§ 261.8 PCB Wastes Regulated UnderToxic Substance Control Act

The disposal of PCB-containingdielectric fluid and electric equipmentcontaining such fluid authorized for useand regulated under part 761 of thischapter and that are hazardous onlybecause they fail the test for theToxicity Characteristic (HazardousWaste Codes D018 through D043 only)are exempt from regulation under parts261 through 265, and parts 268, 270, and124 of this chapter;and the notificationrequirements of section 3010 of RCRA.

4. Section 261.24 is revised to read asfollows:

§ 261.24 Toxicity characteristic.(a) A solid waste exhibits the

characteristic of toxicity if, using the test'methods described in Appendix II orequivalent methods approved by theAdministrator under the procedures setforth in § § 260.20 and 260.21, the extractfrom a representative sample of thewaste contains any of the contaminantslisted in Table I at the concentrationequal. to or greater than the respectivevalue given in that Table. Where the,waste contains less than 0.5 percentfilterable solids, the waste itself, after -filtering using the methodology outlinedin Appendix II, is considered to be theextract for the purpose of this section.

(b) A solid waste that exhibits thecharacteristic of toxicity, but is notlisted as a hazardous waste in subpartD, has the EPA Hazardous WasteNumber specified in Table 1 which

corresponds to the toxic contaminantcausing it to be hazardous.

TABLE 1.-MAXIMUM CONCENTRATION OF

CONTAMINANTS FOR THE TOXICITYCHARACTERISTIC

EPA Regula-

HW Contaminant CAS No.* toevN° (aLevel

No.' (mg/I)

D0040005D018008DO069D019

D020D021D0220007D023D024D025D026D016D027

0028

D029

0030

D0120031

D032

D033

D034

D008D0130009D014D035

D036D037

D0380010D011D039

001515040

D041

D042

D017D043

Arsenic ..................Barium ...................Benzene ................Cadmium ...............

Carbontetrachloride.

Chlordane .............Chlorobenzene.Chloroform ............Chromium .............o-Cresol ................m-Cresol ...............p-Cresol .................Cresol ....................2.4-D ......................

1,4-Dichloroben-zene.

1,2-Dichloroeth-ane.

1,1-Dichloroethy-lene.

2,4-Dinitrotoluene.

Endrin ....................Heptachlor (and

its hydroxide).Hexachloroben-

ZOne.Hexachlorobuta-

diene.Hexachloroeth-

ane.Lead ......................Undane .................Mercury .................Methoxychlor ........Methyl ethyl

ketone.Nitrobenzene ........Pentrachloro-

phenol.Pyridine .................Selenium ...............Silver .....................Tetrachloroethyl-

ene.Toxaphene ............Trichloroethyl-

ene.2,4,5-

Trichloro-phenol

2,4,6-Trichloro-phenol.

2,4,5-TP (Silvex)...Vinyl chloride ........

7440-38-27440-39-3

71-43-27440-43-9

56-23-5

57-74-9108-90-7

67-66-37440-47-3

95-48-7108-39-4106-44-5

94-75-7106-46-7

107-06-2

75-35-4

121-14-2

72-20-876-44-8

118-74-1

87-6-3

67-72-1

7439-92-158-89-9

7439-97-672-43-578-93-3

98-95-387-86-5

110-86-17782-49-27440-22-4

127-18-4

8001-35-279-01-6

95-95-4

88-06-2

93-72-175-01-4

5.0100.0

0.51.00.5

0.03100.0

6.05.0.

4200.04 200.04200.0'200.0

10.07.5

0.5

0.7

- 30.13

0.02

0.008

30.13

0.5

3.0

5.00.40.2

10.0200.0

2.0100.0

35.01.05.00.7

0.50.5

400.0

2.0

1.00.2

I Hazardous waste number.2 Chemical abstracts service number.3 Ouantitation limit is greater than the calculated

regulatory level. The quantitation limit therefore be-comes the regulatory level.• If o-, m-, and p-Cresol concentrations cannot be

differentiated, the total cresol (026) concentrationis used. The regulatory level of total cresol is 200mg/L.


Federal Register / Vol. 55, No. 61 / Thursday,, March 29,, 1990 / Rules and Regulations 11863'

5. Section 261.30 is amended byrevising paragraph (b) to read asfollows:§ 261.30 General.

(b) The Administrator will indicate hisbasis for listing the classes or types ofwastes listed in this subpart byemploying one or more of the followingHazard Codes:

Ignitable W aste ...................................... (l)Corrosive W aste ........................................ (C)Reactive W aste .......................................... (R)Toxicity Characteristic Waste ............ (E)Acute Hazardous W aste .......................... (H)Toxic W aste ................................................ (T)

Appendix VII identifies the constituentwhich caused the Administrator to listthe waste as a Toxicity CharacteristicWaste (E) or Toxic Waste (T) in§ § 261.31 and 261.32.

6. Appendix II of part 261 is revised toread as follows:

Appendix Il---Method 1311 ToxicityCharacteristic Leaching Procedure(TCLP)1.0 Scope and Application

1.1 The TCLP is designed to determine themobility of both organic and inorganic:contaminants'present in liquid, solid, andmultiphasic wastes.

1.2 If a total analysis of the wastedemonstrates that individual contaminantsare not present in the waste, or that they arepresent but at such low concentrations thatthe appropriate regulatory thresholds couldnot possibly be exceeded, the TCLP need nothe run.

1.3 If an analysis of any one of the liquidfractions of the TCLP extract indicates that aregulated compound is present at such highlevels that even after accounting for dilutionfrom the other fractions of the extract theconcentration would be above the regulatorythreshold for that compound, then the-waste,is hazardous and it is not-necessary toanalyze the remaining fractions of theextract.

1.4 If an analysis of extract obtainedusing a bottle extractor shows that theconcentration of any regulated volatilecontaminant exceeds the regulatory threshold

for that compound, then the waste ishazardous and extraction using the ZHE isnot necessary. However, extract from a bottleextractor cannot be used to demonstrate thatthe.concentration of volatile compounds isbelow the regulatory threshold.

2.0 Summary of Method (see Figure 1)'2.11 For liquid wastes (i.e, those,

containing less than 0.5 percent dry solidmaterial), the waste, after filtration through at0.6 to 0.8-um glass fiber filter, is defined asthe TCLP extract.

2.2 For wastes containing greater than orequal'to 0.5 percent solids, the liquid ifany,is separated from the solid phase and'storedfor later anaLysis; the solid phase, if'necessary, is reduced in particle size. Thesolid phase is extracted with an amount ofextraction fluid equal to.20 times the weightof' the solid phase. The extraction fluidemployedis a function of the alkalinity of thesolid phase of the waste. A special extractorvessel is used when testing for volatilecontaminants (see Table I for a list of volatilecompounds). Following extraction, the liquidextract is separated from the solid phase byfiltration through a 0.6 to 0.8-um glass fiberfilter.BILLING. CODE 6560-50-M



Figure 1 Method 1311 Flowchart

Use a sub-sample of waste

BILUNG CODE 6560-50-C


Federal Register / Vol. 55,, No.. 61 /' Thursday,. March .29, 1990, / Rules and Regulations 11865

TABLE 1.-VOLATILE CONTAMINANTS '

Compound CAS no.

Acetone .....................................................Benzene ....................................................n-Butyl alcohol .......................Carbon. disulfide .......................................Carbon tetrachloride .................................Chlorobenzene .........................................Chloroform .. .............. ...... .................1,2-Dichloroethane ..................................1,1 -Dichloroethylene ................................Ethyl acetate .............................................Ethyl benzene ....................... ...............Ethyl ether .................................................Isobutanol ..................................................M ethanol ....................................................M ethylene chloride ...................................M ethyl ethyl ketone ..................................M ethyl isobutyl ketone .............................Tetrachloroethylene .................................Toluene .................................................. *..1,1.1 -Trichloroethane ..............................Trichloroethylene ............. ..............Trichlorofluorom ethane ...........................1,1,2-Tichloro-1,2,2-tfluoroethane.Vinyl chlonde ...... ..... .............

67-64-171-43-271-36-3'75-15-056-23;-5

108-90-767-66-3,

107-06-2.75-35-4141-78-6100-41-460-29-778-83-167-56-175-09-278-93-3

108-10-1127-18-4108-88-371-55-679-01-675-69-476-13-175-01-4

TABLE 1.-VOLATILE CONTAMINANTS I-Continued

Compound

Xylene . ......................

'When, testing for, any or. all! ofnant, the zero-headspace, extractor,used instead of the bottle extractor.

2.3 If compatible (i.e., multipnot form on combination). the irphase of the waste is added to Iextract, and these are analyzedincompatible, the liquids are anseparately and the results are ncombined to yield a volume-weaverage concentration.

3.0 Interferences

3.1 Potential interferences thencountered during analysis arethe individual analytical metho

4.0 Apparatus and Materials

4.1, Agitation apparatus: The agitationapparatus must be capable of rotating the

CAS no. extraction vessel'in an' endover-end fashion(see Figure 2) at 30 +2 rpm. Suitable devices,

.130-20-7 known to EPA are identified in Table 2.4.2 Extraction Vessel:

these contami- 4.2.1 Zero-Headspace Extraction Vesselvessel shall be (ZHE]. This device is for use only'when the

waste is being tested for the mobility/ofvolatile constituents (i.e., those listedin

le phases will Table 1.). The ZHE (depicted in Figure 3)nitial liquid allows fbr liquid/solid separation within thehe liquid device, and effectively precludes headspace.together. If This type of vessel allows for initial liquid/alyzed solid separation, extraction, and final extract

nathematically filtration without opening the vessel (see-stepighted 4.3.1). The vessels shall have an internalvolume of 500-600 mL and be equipped to

accommodate a 90-110 mm filter. The devicescontain VITON R I 0-rings which should bereplaced frequently:. Suitable ZHE devices

hat may be known to EPA are identifiedlin Table 3.discussed in

ds.BILUNG CODE 6560-50-M

VITON I is a trademark of Dii Pont.



Figure 2. Rotary Agitation ApparatusBiLLING CODE 6560-50-C


Federal Register / Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations 11867

TABLE 2.-SUITABLE ROTARY AGITATION APPARATUS 1

Company Location Model no.

Analytical Testing and Consulting Services, Inc ................................................................ Warrington, PA (215) 343-4490.. 2-ZHE or 4-bottle extractor (DC20S); 4-ZHE or8-bottle extractor (DC20); 6-ZHE or 12-bottleextractor (DC208).

Associated Design and Manufacturing Company .............................................................. Alexandria, VA (703) 549-5999.. 2-vessel (3740-2). 4-vessel (3740-4). 6-vessel(3740-6). 8-vessel (3740-8). 12-vessel(3740-12). 24-vessel (3740-24).

Environmental Machine and Design, Inc ............................................................................ Lynchburg, VA (804) 845-6424.. 8-vessel (08-00-00). 4-vessel (04-00-00).IRA Machine Shop and Laboratory ..................................................................................... Santurce, PR (809) 752-4004 . 8-vessel (011001).Lars Lande Manufacturing ............................................................................................ Whitmore Lake, MI (313) 449- 10-vessel (10VRE). 5-vessel (5 VRE).

4116.Millipore Corp .......................................................................................................................... Bedford, MA (800) 225-3384 . 4-ZHE or 4 -liter bottle extractor

(YT300RAHW).

'Any device that rotates the extraction vessel in an end-over-end fashion at 30 +2 rpm is acceptable.

BILLING CODE 6560-50-M


11868 Federal Register / Vol. 55, No. 6i / Thursday, March 29, 1990 / Rules and Regulations

Liquid Inlet/Outlet Valve

Support

Viton c

Gas

Bottom Flange -,

Pressurized Gas--rInletOutlet Valve Gauge

Figure 3. Zero-Headspace Extractor (ZHE)BILLING CODE 6560-50-C



TABLE 3.-SUITABLE ZERO-HEADSPACE EXTRACTOR VESSELS

Company Location Model no.

Analytical Testing & Consulting Services. Inc .................................................................... Warrington, PA (215) 343-4490.. C102, Mechanical Pressure Device.Associated Design and Manufacturing Company .............................................................. Alexandria, VA (703) 549-5999.. 3745-ZHE, Gas Pressure Device.Lars Lands Manufacturing 2 ................................................................................................. Whitmore Lake, MI (313) 449- ZHE-1 1, Gas Pressure Device.

4116.Millipore Corporation .......................................................................................... Bedford, MA (800) 225-3384 . YT3009OHW, Gas Pressure Device.Environmental Machine and Design, Inc ............................................................................ Lynchburg, VA (804) 845-6424. VOLA-TOXi, Gas Gas Pressure Device.

Any device that meets the specifications listed in Section 4.2.1 of the method is suitable.2 This device uses a 110 mm filter.

For the ZHE to be acceptable for use, the extraction fluid is needed. Headspace is. fiber filter and able to withstand the pressurepiston within the ZHE should be able to be allowed in this vessel. needed to accomplish separation may bemoved with approximately 15 psi or less. If it The extraction bottles may be constructed used. Suitable filter holders range fromtakes more pressure to'move the piston, the from various materials, depending on the simple vacuum units to relatively complex0-rings in the device should be replaced. If contaminants to be analyzed and the nature systems capable of exerting pressures of upthis does not solve the problem, the ZHE is of the waste (see Step 4.3.3). It is to 50 psi or more. The type of filter holderunacceptable for TCLP analyses and the recommended that borosilicate glass bottles used depends on the properties of themanufacturer should be contacted. be used instead of other types of glass, material to be filtered (see Step 4.3.3). These

The ZHE should be checked for leaks after especially when inorganics are of concern, devices shall have a minimum internalevery extraction. If the device contains a Plastic bottles, other than polytetrafluoro- volume of 300 mL and be equipped tobuilt-in pressure gauge, pressurize the device ethylene, shall not be used if organics are to accommodate a minimum filter size of 47 mmto 50 psi, allow it to stand unattended for I be investigated. Bottles are available from a (filter holders having an internal capacity ofhour, and recheck the pressure. If the device number of laboratory suppliers. When this 1.5 L or greater and equipped todoes not have a built-in pressure gauge, type of extraction vessel is used, the filtration accommodate a 142 mm diameter filter are

pressurize the device to 50 psi, submerge it in device discussed in Step 4.3.2 is used for recommended). Vacuum filtration can only be

water, and check for the presence of air initial liquid/solid separation and final used for wastes with low solids content (< 10

bubbles escaping from any of the fittings. if extract filtration. percent) and for highly granular liquid-4.3 Filtration Devices: It is recommended containing wastes. All other types of wastes

pressure is lost, check all fittings and inspect that all filtrations be performed in a hood. should be filtered using positive pressureand replace 0-rings, if necessary. Retest the 4.3.1 Zero-Headspace Extractor Vessel filtration. Suitable filter holders known todevice. If leakage problems cannot be solved, (ZHE): When the waste is evaluated for EPA are shown in Table 4.the manufacturer should be contacted. volatiles, the zero-headspace extraction 4.3.3 Materials of Construction:

Some ZHEs use gas pressure to actuate the vessel described in section 4.2.1 is used for Extraction vessels and filtration devices shallZHE piston, while others use mechanical filtration. The device shall be capable of be made of inert materials which will notpressure (see Table 3). Whereas the volatiles supporting and keeping in place the glass leach or absorb waste components. Glass,procedure (see section 9.0) refers to pounds- fiber filter and be able to withstand the polytetrafluoroethylene (PTFE), or type 316per-square-inch (psi), for the mechanically pressure needed to accomplish separation (50 stainless steel equipment may be used whenactuated piston, the pressure applied is psi). evaluating the mobility of both organic andmeasured in torque-inch-pounds. Refer to the . Note: When it is suspected that the glass inorganic components. Devices made of high-manufacturer's instructions as to the proper fiber filter has been ruptured, an in-line glass density polyethylene (HDPE), polypropylene,conversion. fiber.filter may be used to filter the material or polyvinyl chloride may be used only when

4:2.2 Bottle Extraction Vessel. When the within the ZHE. evaluating the mobility of metals. Borosilicatewaste is being evaluated using the 4.3.2 Filter Holder- When the waste is glass bottles are recommended for use overnonvolatile extraction, a jar with sufficient evaluated for other than volatile compounds, other types of glass bottles, especially whencapacity to hold the sample and the any filter holder capable of supporting a glass inorganics are constituents of concern.

TABLE 4.-SUITABLE FILTER HOLDERS 1

Company Location Model/Catalogue no. Size (um)

Nucleopore Corporation ........................................................ Pleasanton, CA (800) 882-7711 ................... 425910 410400 ..................................................... 142 mm47 mm

Micro Filtration Systems ...................................................... Dublin, CA (800) 334-7132 (415) 828-6010 ........ 302400 311400 ................................ ........ 142 mm47 mm

Millipore Corporation ...................... Bedford, MA (800) 225-3384 ............ YT30142HW XX1004700 ............................ 142 mm47 mm

Any device capable of separating the liquid from the solid phase of the waste is suitable, providing that it is chemically compatible with the waste and theconstituents to be analyzed. Plastic devices (not listed above) may be used when only inorganic contaminants are of concern. The 142 mm size filter holder isrecommended.

4.4 Filters: Filters shall be made ofborosilicate glass fiber, shall contain nobinder materials, and shall have an effectivepore size of 0.6 to 0.8-urn or equivalent. Filtersknown to EPA which meet thesespecifications are identified in Table 5. Pre-

filters must not be used. When evaluating themobility of metals, filters shall be acid-washed prior to use by rinsing with 1N nitricacid followed by three consecutive rinseswith deionized distilledwater (a minimum of1-L per rinse is recommended). Glass fiber

filters are fragile and should be handled withcare.

4.5 pI meters: The meter should beaccurate to +0.05 units at 25 *C.

11869


11870 Federal Register / VoL 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

TABLE 5.-SUITABLE FILTER MEDIA 1

Company Location Model Pore size

Millipor Corporation ............................................................ Bedford, MA (800) 225-3384, ................................ AP40 ......................... ............................................. I01Nucleopore Corporation ....................................................... Pleasanton, CA (415) 463-2530 ....................... 211625 .. . . .................... 07,Whatman Laboratory. Products, Ic.................................... Clifton, NJ (201) 773-5800 ..................................... GFF ..................................... 0.7'Micro Filtration Systems ....................................................... Dublin, CA (800) 334-7132 (415) 828-6010 .. GF75 ........................................................................ 0.7

Any filter that meets the specifications in Section 44 of the Method is suitable.

4.6 ZHE extract collection devices:TEDLARR2 bags or glass, stainless steel orPTFE gas-tight syringe& are used to collectthe initial liquid'phase.and thefinal extract ofthe waste when.using the ZHE device. Thedevices listed are recommended for useunder the following conditions:

4.6.1 If a waste contains an aqueousliquid phase or if. a waste does not contain asignificant amount of'nonaqueous liquid (i.e.,<1 percent of total waste), the TEDLAR ' bag.or a 600 mL syringe should be used to collectand combine the initial liquid and solidextract.

4.6.2 If a waste contains a significantamount of nonaqueous liquid in the initialliquid phase [i.e., >1 percent oftotal waste)the syringe or the TEDLARR bag may be usedfor both the Initial solid/liquid separationand the final extract filtration. Howeveranalysts should use one or the other, notboth.

4.6.3 If the waste contains no initial liquidphase (is 100 percent solid) or has nosignificant solid phase (is 100 percent liquid).either the TEDLARR bag or'the syringe maybe used If the syringe is used discard the-first 5 mL of liquid expressed from the device.The remaining aliquots are used for analysis.

4.7 ZHE'extraction fluid transfer devices:Any device capable of transferring theextraction fluid into the ZHE withoutchanging the-nature of-the extraction fluid-isacceptable-(e.g-, a positive displacement orperistaltic pump, a gas tight syringe, pressurefiltration unit (See Step 4.3.2), or other ZHEdevice).

4.8 Laboratory balance: Any laboratorybalance accurate to within +0.01 grams maybe used (all weight measurements are to bewithin +0.1 grams).

5.0 Reagents5.1 Reagent water. Reagent water is

defined as water in which an interferant isnot observed at or above the methodsdetection limit, of the analyte(s) of interest.For nonvolatile extractions, ASTM Type Iwater or equivalent meets the definition ofreagent water. For volatile extractions, it isrecommended that reagent water begenerated by any of-the following methods..Reagent water should be monitoredperiodically for impurities.

5.1.1 Reagent water for volatileextractions may be generated by passing tapwater through a carbon filter bed containingabout 500'grams.of activated carbon (CalgonCorp., Filtrasorb-300 or equivalent).

5.1.2 A water purification system(Millipore Super-Q or equivalent) may also beused to generate reagent water for volatileextractions.

2 TEDLARa is a registered trademark of Du Pont.

5.1.3 Reagent water for volatileextractions may also be prepared by boilingwater for 15 minutes. Subsequently, whilemaintaining the water temperature at 90:+5*C. bubble a contaminant-free Inert gas. (e.g.,nitrogen)-through the water for 1 hour. Whilestill hot transfer the water to a narrow mouthscrew-cap bottle under zero-headspace:andseal with a Teflon-lined septum and cap.

.5.2 Hydrochloric acid[1N). HCI, madefrom ACSreagent grade;

5.3 Nitric acid (1N), HN03. made fromACS reagent grade.

5.4 Sodium-hydroxide (IN), NaOQ- madefrom ACS reagent grade.

5.5 Glacial acetic acid. HOAc, ACSreagent; grade.

5.6 Extraction fluid.5.6.1 Extraction fluid #1: Add 5.7 ML

glacial. HOAc to 500 mL ofthe appropriatewater (See Step 5.1),,add:64;3 mL of 1NNaQH, and dilute to a volume of 1 liter.When correctly prepared; the pH of this fluidwill be 4.93 +0.05.

5.6.2 Extraction fluid #2: Dilute!5.7 mL.glacial HOAc-with ASTM Type H water (SeeStep 5.1)'to a-volume of 1 liter. Whencorrectly prepared, the pH of: this fluid will be2.88+0,05.

Note: These extraction fluids should bemonitored frequently-for impurities The pHshould be checked prior to use, to ensure thatthese fluids are made up accurately. Ifimpurities are found or the pH is not withinthe above specifications; the fluid shall bediscarded and fresh extraction fluidprepared.

5.7 Analytical standards preparedaccording to the appropriate analyticalmethod.

6.0 Sample Collection; Preservation, andHandling

6.1 All samples shall be collected using,an appropriate sampling plan.

6.2 The TCLP may place requirements onthe minimal size of the field sample-depending upon the physical state or states ofthe waste.and the contaminants of concern.An aliquot is needed for preliminaryevaluation of which extraction fluid is to beused for the nonvolatile contaminantextraction procedure. Another aliquot may beneeded to actually conduct the nonvolatileextraction (see section 1.4 concerning the useof this extract for volatile organics). Ifvolatile organics are of concern,, anotheraliquot may be needed. Quality controlmeasures may require additional aliquots.Further, it is always wise to collect moresample just in case something goes wrongwith the initial attempt to conduct the test.

6.3 Preservatives shall not be added tosamples.

6.4 Samples may be refrigerated unlessrefrigeration results in irreversible physicalchange to the waste- If precipitation occurs.the entire-sample (including precipitate)should be extracted.

6.5 When the waste is to be evaluated forvolatile contaminants, care shall-be taken tominimize the loss of:volatiles. Samples shallbe taken and. stored in a- manner to preventthe loss of volatile contaminants (e.g,,samples should be collected in Teflon-inedseptum capped vials and stored at 4, °C, until,ready to be opened prior to extraction).

6.6 TCLP extracts. should be prepared for-analysis and analyzed as soon.as possiblefollowing extraction. Extracts or portions of,extracts for metallic contaminantdeterminations.must be acidified with nitricacid to a pH <2, unless precipitation.occurs(see section 8.14 if precipitation. occurs).Extracts or portions of. extracts for-organic.contaminant determinations, shall not beallowed to come into contact with theatmosphere (i.e.. no headspace) to preventlosses. See section 10.0 (QA requirements) foracceptable sample and extract holding times.

7.0 Preliminary Evaluations

Perform. preliminary TCLP evaluations on aminimum 100 gram. aliqout of. waste. Thisaliquot may not actually undergo TCLPextraction. These preliminary evaluations.include: (1) determination.of the percentsolids; (2) determination of whether the waste.contains insignificant solids.and is. therefore.its own extract after filtration; (3)determination of whether the solid portion ofthe waste requires particle size reduction;and (4) determination of which of the twoextraction, fluids are to be-used for thenonvolatile TCLP extraction of the waste.

7.1 Preliminary determination of percentsolids: Percent. solids. is defined as thatfraction of a waste sample (as.a percentageof the total sample) from which no liquid maybe forced out by an applied pressure, asdescribed below.

7.1.1 If the waste will obviously yield nofree-liquid when subjected to pressurefiltration (i.e., is 100% solids) proceed to Step7.3.

7.1.2 If the sample is liquid or multiphasic,liquid/solid separation to make a preliminary,determination of percent solids is required.This involves the filtration devicedescribed-in Step 4.3.2 and is outlinedJin Steps 7.1.3.through 7.1.9.

7.1.3 Pre-weigh, the filter-and thecontainer that will receive the filtrate.

7.1.4 Assemble the filter holder and filterfollowing the manufacturer's instructions.Place the filter on the support screen andsecure.



7.1.5 Weigh out a subsample of the waste(100 gram minimum) and record the weight.

7.1.6 Allow slurries to stand to permit thesolid phase to settle. Wastes that settleslowly may be centrifuged prior to filtration.Centrifugation is to be used only as an aid tofiltration. If used, the liquid should bedecanted and filtered followed by filtration ofthe solid portion of the waste through thesame filtration system.

7.1.7 Quantitatively transfer the wastesample to the filter holder (liquid and solidphases). Spread the waste sample evenlyover the surface of the filter. If filtration ofthe waste at 4 °C reduces the amount ofexpressed liquid over what would beexpressed at room temperature then allowthe sample to warm up to room temperaturein the device before filtering.Note: if waste material (>1 percent oforiginal sample weight) has obviouslyadhered to the container used to transfer thesample to the filtration apparatus, determinethe weight of this residue and subtract it fromthe sample weight determined in Step 7.1.5 to

determine the weight of the waste samplethat will be filtered.

Gradually apply vacuum or gentle pressureof 1-10 psi, until air or pressurizing gas movesthrough the filter. If this point is not reachedunder 10 psi, and if no additional liquid haspassed through the filter in any 2-minuteinterval, slowly increase the pressure in 10-psi increments to a maximum of 50 psi. Aftereach incremental increase of 10-psi, if thepressurizing gas has not moved through thefilter, and if no additional liquid has passedthrough the filter in any 2-minute interval,proceed to the next 10-psi increment. Whenthe pressurizing gas begins to move throughthe filter, or when liquid flow has ceased at50 psi (i.e . filtration does not result in anyadditional filtrate within any 2-minuteperiod), stop the filtration.. Note: Instantaneous application of highpressure can degrade the glass fiber filter andmay cause premature plugging.

7.1.8 The material in the filter holder isdefined as the solid phase of the waste, andthe filtrate is defined as the liquid phase.

Note: Some wastes, such as oily wastesand some paint wastes, will obviouslycontain some material that appears to be aliquid. Even after applying vacuum orpressure filtration, as outlined in Step 7..7,this material may not filter. If this is the case.the material within the filtration device isdefined as a solid. Do not replace the originalfilter with a fresh filter under anycircumstances. Use only one filter.

7.1.9 Determine the weight of the liquidphase by subtracting the weight of the filtratecontainer (see Step 7.1.3) from the totalweight of the filtrate-filled container.Determine the weight of the solid phase ofthe waste sample by subtracting the weightof the liquid phase from the weight of thetotal waste sample, as determined in Step7.1.5 or 7.1.7.

Record the weight of the liquid and solidphases. Calculate the percent solids asfollows:

Percent solids =Weight of solid (Step 7.1-9)-

Total weight of waste (Step 7.1.5 or 7.1.7]

7.2 If the percent solids determined inStep 7.1.9 is equal to or greater than 0.5%,then proceed either to Step 7.3 to determinewhether the solid material requires particlesize reduction or to Step 7.2-1 if it is noticedthat a small amount of the filtrate isentrained in wetting of the filter. If thepercent solids determined in Step 7.1.9 is lessthan 0.5%, then proceed to Step 8.9 if the

nonvolatile TCLP is to be performed and tosection 9.0 with a fresh portion of the waste ifthe volatile TCLP is to be performed.

7.2.1 Remove the solid phase and filterfrom the filtration apparatus.

7.2.2 Dry the filter and solid phase at 100+20 "C until two successive weighing yieldthe same value within + 1 percent. Recordthe final weight.

Note: Caution should be taken to ensurethat the subject solid will not flash uponheating. It is recommended that the dryingoven be vented to a hood or otherappropriate device.

7.2.3 Calculate the percent dry solids as,follows:

Percent dry solids =(Weight of dry waste+flter)-tared weight of filter

Initial weight of waste (Step 7.1.5 or 7.1.7)

7.2.4 If the percent dry solids is less than0.5 percent, then proceed to Step 8.9 if thenonvolatile TCLP is to be performed, and toSection 9.0 if the volatile TCLP is to beperformed. If the percent dry solids is greaterthan or equal to 0.5%, and if the nonvolatileTCLP is to be performed, return to thebeginning of this Section (7.0) and, with afresh portion of waste, determine whetherparticle size reduction is necessary (Step 7.3)and determine the appropriate extraction"fluid (Step 7.4). If only the volatile TCLP is tobe performed, see the note in Step 7.4.

7.3 Determination of whether the wasterequires particle-size reduction (particle-sizeis reduced during this step): Using the solidportion of the waste, evaluate the solid forparticle size. Particle-size reduction isrequired, unless the solid has a surface areaper gram of material equal to or greater than3.1 cm 2 , or is smaller than I cm in itsnarrowest dimension (i.e. is capable ofpassing through a 9.5 mm (0.375 inch)standard sieve). If the surface area is smalleror the particle size larger than describedabove, prepare the solid portion of the wastefor extraction by crushing, cutting, or grinding

the waste to a surface area or particle-size asdescribed above. If the solids are preparedfor organic volatiles extraction, specialprecautions must be taken, see Step g.0.

Note Surface area criteria are meant forfilamentous (e.g., paper, cloth, and similarlwaste materials. Actual measurement ofsurface area is not required, nor is itrecommended. For materials that do notobviously meet the criteria, sample-specificmethods would need to be developed andemployed to measure the surface area. Suchmethodology is currently not available.

7.4 Determination of appropriateextraction fluid: If the solid content of thewaste is greater than or equal to 05 percentand if TCLP extraction for nonvolatileconstituents will take place (Section 8.0).perform the determination of the appropriatefluid (Step 5.6) to use for the nonvolatilesextraction as follows:

Note: TCLP extraction for volatileconstituents uses only extraction fluid #1(Step 5.6.1). Therefore, if TCLP extraction fornonvolatiles is not required, proceed toSection 9.0.

7.4.1 Weigh out a small subsample of thesolid phase of the waste, reduce the solid (ifnecessary) to a particle-size of approximately1 mm in diameter or less, and transfer 5.0grams of the solid phase of the waste to a500-mL beaker or Erlenmeyer flask.

7.4.2 Add 96.5 mL of reagent water(ASTM Type I) to the beaker, cover with awatchglass, and stir vigorously for 5 minutesusing a magnetic stirrer. Measure and recordthe pH. If the pH is <5.0, use extraction fluid#1. Proceed to Section 8.0.

7.4.3 If the pH from Step 7.4.2 is >5.0, add3.5 mL 1N HCI. slurry briefly, cover with awatchglass, heat to 50 °C, and hold at 50 °Cfor 10 minutes.

7.4.4 Let the solution cool to roomtemperature and record the pH. If the pH is<5.0, use extraction fluid #1. If the pH is>5.0, use extraction fluid #2. Proceed toSection 8.0.

7.5 If the aliquot of the waste used for thepreliminary evaluation (Steps 7.1-7.4) wasdetermined to be 100% solid at Step 7.1.1,then it can be used for the Section 8.0extraction (assuming at least 100 grams

X 100

X 100

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remain), and the section 9.0 extraction(assuming at least 25 grams remain). If thealiquot was subjected to the procedure inStep 7.1.7, then another aliquot shall be usedfor the volatile extraction procedure inSection 9.0. The aliquot of the wastesubjected to the procedure in Step 7.1.7 mightbe appropriate for use for the section 8.0extraction if an adequate amount of solid (asdetermined by Step 7.1.9) was obtained. Theamount of solid necessary is dependent uponwhether a sufficient amount of extract will beproduced to support the analyses. If anadequate amount of solid remains, proceed toStep 8.10 of the nonvolatile TCLP extraction.

8.0 Procedure When Volotiles Are NotInvolved

A minimum sample size of 100 grams (solidand liquid phases) is required. In some cases,a larger sample size may be appropriate,depending on the solids content of the wastesample (percent solids, See Step 7.1), whetherthe initial liquid phase of the waste will bemiscible with the aqueous extract of thesolid, and whether inorganics, semivolatileorganics, pesticides, and herbicides are allanalytes of concern. Enough solids should begenerated for extraction such that the volumeof TCLP extract will be sufficient to support-all of the analyses required. If the amount ofextract generated by a single TCLP extractionwill not be sufficient to perform all of theanalyses, more than one extraction may beperformed and the extracts from eachcombined and aliquoted for analysis.

8.1 If the waste will obviously yield noliquid when subjected to pressure filtration(i.e.,- is 100 percent solid, see Step 7.1), weighout a subsample of the waste (100 gramminimum) and proceed to Step 8.9.

8.2 If the sample is liquid or multiphasic,liquid/solid separation is required. Thisinvolves the filtration device described inStep 4.3.2 and is outlined in Steps 8.3 to 8.8.

8.3 Pre-weigh the container that willreceive the filtrate.

8.4 Assemble the filter holder and filterfollowing the manufacturer's instructions.Place the filter on the support screen andsecure. Acid wash the filter if evaluating themobility of metals (see Step 4.4).

Note: Acid washed filters may be used forall nonvolatile extractions even when metalsare not of concern.

8.5 Weigh out a subsample of the waste(100 gram minimum) and record the weight. Ifthe waste contains <0.5 percent dry solids(Step 7.2), the liquid portion of the waste,after filtration, is defined as the TCLPextract. Therefore, enough of the sampleshould be filtered so that the amount offiltered liquid will support all of the analysesrequired of the TCLP extract. For wastescontaining >0.5 percent dry solids (Step 7.1or 7.2), use the percent solids informationobtained in Step 7.1 to determine theoptimum sample size (100 gram minimum) forfiltration. Enough solids should be generatedby filtration to support the analyses to beperformed on the TCLP extract.

8.8 Allow slurries to stand to permit thesolid phase to settle. Wastes that settleslowly may be centrifuged prior to filtration.Use centrifugation only as an aid to filtration.If the waste is centrifuged, the liquid shouldbe decanted and filtered followed byfiltration of the solid portion of the wastethrough the same filtration system.

8.7 Quantitatively transfer the wastesample (liquid and solid phases) to the filterholder (see Step 4.3.2). Spread the wastesample evenly over the surface of the filter. Iffiltration of the waste at 4 °C reduces theamount of expressed liquid over what wouldbe expressed at room temperature, thenallow the sample to warm up to roomtemperature in the device before filtering.

Note: If waste material (>1 percent of theoriginal sample weight) has obviouslyadhered to the container used to transfer thesample to the filtration apparatus, determinethe weight of this residue and subtract it fromthe sample weight determined in Step 8.5, todetermine the weight of the waste samplethat will be filtered.

Gradually apply vacuum or gentle pressureof 1-10 psi, until air or pressurizing gas movesthrough the filter. If this point is not reachedunder 10 psi, and if no additional liquid haspassed through the filter in any 2-minuteinterval, slowly increase the pressure in 10-psi increments to a maximum of 50 psi. Aftereach incremental increase of 10 psi, if thepressurizing gas has not moved through thefilter, and if no additional liquid has passedthrough the filter in any 2-minute interval,proceed to the next 10-psi increment. Whenthe pressurizing gas beginsto move throughthe filter, or when the liquid flow has ceased

at 50 psi (i.e., filtration does not result in anyadditional filtrate within a 2-minute period),stop the filtration.

Note: Instantaneous application of highpressure can degrade the glass fiber filter andmay cause premature plugging.

8.8 The material in the filter holder isdefined as the solid phase of the waste, andthe filtrate is defined as the liquid phase.Weigh the filtrate. The liquid phase may nowbe either analyzed (See Step 8.12) or stored at4 °C until time of analysis.

Note: Some wastes, such as oily wastesand some paint wastes, will obviouslycontain some material that appears to be aliquid. Even after applying vacuum orpressure filtration, as outlined in Step 8.7, thismaterial may not filter. If this is the case, thematerial within the filtration device isdefined as a solid and is carried through theextraction as a solid. Do not replace theoriginal filter with a fresh filter under anycircumstances. Use only one filter.

8.9 If the waste contains <0.5 percent drysolids (see Step 7.2), proceed to Step 8.13. Ifthe waste contains >0.5 percent dry solids(see Step 7.1 or 7.2), and if particle-sizereduction of the solid was needed in Step 7.3,proceed to Step 8.10. If the waste as receivedpasses a 9.5 mm sieve, quantitatively transferthe solid material into the extractor bottlealong with the filter used to separate theinitial liquid from the solid phase, andproceed to Step 8.11.

8.10 Prepare the solid portion of the wastefor extraction by crushing, cutting, or grindingthe waste to a surface area or particle-size asdescribed in Step 7.3. When the surface areaor particle-size has been appropriatelyaltered, quantitatively transfer the solidmaterial into an extractor bottle. Include thefilter used to separate the initial liquid fromthe solid phase.

Note: Sieving of the waste is not normallyrequired. Surface area requirements aremeant for filamentous (e.g., paper, cloth) andsimilar waste materials. Actual measurementof surface area is not recommended. Ifsieving is necessary, a Teflon-coated sieveshould be used to avoid contamination of thesample.

8.11 Determine the amount of extractionfluid to add to the extractor vessel as follows:

Weight of extraction fluid -20 Xpercent solids (Step 7.1) X weight of waste filtered (Step 8.5 or 8.7)

Slowly add this amount of appropriateextraction fluid (see Step 7.4) to the extractorvessel. Close the extractor bottle tightly (it isrecommended that Teflon tape be used toensure a tight seal), secure in rotary agitationdevice, and rotate at 30+2 rpm for 18+2hours. Ambient temperature (i.e., temperatureof room in which extraction takes place) shallbe maintained at 22 +3 °C during theextraction period.

Note: As agitation continues, pressure maybuild up within the extractor bottle for sometypes of wastes (e.g., limed or calciumcarbonate containing waste may evolvegases such as carbon dioxide). To relieveexcess pressure, the extractor bottle may beperiodically opened (e.g., after 15 minutes, 30minutes, and I hour) and vented into a hood.

8.12 Following the 18+2 hour extraction,separate the material in the extractor vesselinto its component liquid and solid phases by

filtering through a new glass fiber filter, asoutlined in Step 8.7. For final filtration of theTCLP extract, the glass fiber filter may bechanged, if necessary, to facilitate filtration.Filter(s) shall be acid-washed (see Step 4.4) ifevaluating the mobility of metals.

8.13 Prepare the TCLP extract as follows:8.13.1 If the waste contained no initial

liquid phase, the filtered liquid materialobtained from Step 8.12 is defined as theTCLP extract. Proceed to Step 8.14.



8.13.2 If compatible (e.g., multiple phaseswill not result on combination), combine thefiltered liquid resulting from Step 8.12 withthe initial liquid phase of the waste obtainedin Step 8.7. This combined liquid is defined asthe TCLP extract. Proceed to Step 8.14.

8.13.3 If the initial liquid phas6 of thewaste, as obtained from Step 8.7, is not ormay not be compatible with the filtered liquidresulting from Step 8.12, do not combine theseliquids. Analyze these liquids, collectivelydefined as the TCLP extract, and combine theresults mathematically, as described in Step8.14.

&14 Following collection of the TCLPextract, the pH of the extract should be

recorded. Immediately aliquot and preservethe extract for analysis. Metals aliquots mustbe acidified with nitric acid to pH< 2. Ifprecipitation is observed upon addition ofnitric acid to a small aliquot of the extract.then the remaining portion of the extract formetals analyses shall not be acidified and theextract shall be analyzed as soon as possible.All other aliquots must be stored underrefrigeration (4 °C) until analyzed. The TCLPextract shall be prepared and analyzedaccording to appropriate analytical methods.TCLP extracts to be analyzed for metals shallbe acid digested except in those instanceswhere digestion causes loss of metalliccontaminants. If an analysis of the

undigested extract shows that theconcentration of any regulated metalliccontaminant exceeds the regulatory level.then the waste is hazardous and digestion ofthe extract is not necessary. However, dataon undigested extracts alone cannot be usedto demonstrate that the waste is nothazardous. If the individual phases are to beanalyzed separately, determine the volume ofthe individual phases (to +0.5 percent).conduct the appropriate analyses, andcombine the results mathematically by usinga simple volume-weghted average:

Final analyte concentration =(Vd(CJ+ (v111(C2)

VI+V 2

where:V, =The volume of the first phase (L).C, =The concentration of the contaminant of

concern in the first phase (mg/LI.V 2 =The volume of the second phase (L).C=The concentration of the contaminant of

concern in the second phase (mg/L).8.15 Compare the contaminant

concentrations in the TCLP extract with thethresholds identified in the appropriateregulations. Refer to J. 10. for qualityassurance requirements.

9.0 Procedure When Volatifes Are InvolvedUse the ZHE device to obtain TCLP extract

for analysis of volatile compounds only.Extract resulting from the use of the ZHEshall not be used to evaluate the mobility ofnonvolatile analytes (e.g., metals, pesticides,etc.).

The ZHE device has approximately a 500-mL internal capacity. The ZHE can thusaccommodate a maximum of 25 grams of'solid (defined as that fraction of a samplefrom which no additional liquid may beforced out by an applied pressure of 5 psi),due to the need to add an amount ofextraction fluid equal to 20 times the weightof the solid phase.

Charge the ZHE with sample only once anddo not open the device until the final extract(of the solid) has been collected. Repeatedfilling of the ZHE to obtain 25 grams of solidis not permitted.

Do not allow the waste, the initial liquidphase, or the extract to be exposed to theatmosphere for any more time than isabsolutely necessary. Any manipulation ofthese materials should be done when cold (4°C) to minimize loss of volatiles.

9.1 Pre-weigh the (evacuated) filtratecollection container (See Step 4.6) and setaside. If using a TEDLAR bag. express allliquid from the ZHE device into the bag.whether for the initial or final liquid/solidseparation. and take an aliquot from theliquid in the bag for analysis. The containerslisted in Step 4.6 are recommended for useunder the conditions stated in 4.8.1-4.6.&

9.2 Place the ZHE piston within the bodyof the ZHE (it may be helpful first to moistenthe piston O-rings slightly with extractionfluid). Adjust the piston within the ZHE bodyto a height that will minimize the distance thepiston will have to move once the ZHE ischarged with sample (based upon sample sizerequirements determined from Section 9.0.Step 7.1 and/or 7.2). Secure the gas inlet/

* outlet flange (bottom flange) onto the ZHEbody in accordance with the manufacturer'sinstructions. Secure the glass fiber filterbetween the support screens and set aside.Set liquid inlet/outlet flange (top flange)aside.

9.3 If the waste is 100 percent solid (seeStep 7.1), weigh out a subsample (25 grammaximum) of the waste, record weight, andproceed to Step 9.5.

9.4 If the waste contains <0.5 percent drysolids (Step 7.2, the liquid portion of waste,after filtration, is defined as the TCLPextract. Filter enough of the sample so thatthe amount of filtered liquid will.support all-of the volatile analyses required. For wastescontaining >0.5 percent dry solids (Steps 7-1and/or 7.2), use the percent solidsinformation obtained in Step 7.1 to determinethe optimum sample size to charge into theZHE. The recommended sample size is asfollows:

9.4.1 For wastes containing <0.5 percentsolids (see Step 7.1)', weigh out a 500-gramsubsample of waste and record the weight.

9.4,2 For wastes containing >0.5 percentsolids (see Step 7.1), determine the amount ofwaste to charge into the ZHE as follows:

25Weight of waste to change ZHE Percent solids (Step 7.1 I

Weigh out a subsample of the waste of theappropriate size and record the weight.

9.5 If particle-size reduction of the solidportion of the waste was required in Step 7.3,proceed to Step 9.6. If particle-size reductionwas not required in Step 7.3, proceed to Step9.7.

9.6 Prepare the waste for extraction bycrushing, cutting, or grinding the solid portionof the waste to a surface area or particle-sizeas described in Step 7.3.1. Wastes andappropriate reduction equipment should berefrigerated, if possible, to 4 'C prior toparticle-size reduction. The means used to

effect particle-size reduction must nutgenerate heat in and of itself. If reduction ofthe solid phase of the waste is necessary,exposure of the waste to the atmosphereshould be avoided to the extent possible.

Note: Sieving of the waste is notrecommended due to the possibility thatvolatiles may be lost. The use of anappropriately graduated ruler isrecommended as an acceptable alternative.Surface area requirements are meant forfilamentous (e.g., paper, cloth) and similarwaste materials. Actual measurement ofsurface area is not recommended.

When the surface area or particle-size hasbeen appropriately altered, proceed to Step9.7.

9.7 Waste slurries need not be allowed tostand to permit the solid phase to settle. Donot centrifuge wastes prior to filtration.

9.8 Quantitatively transfer the entiresample (liquid and solid phases) quickly tothe ZHE. Secure the filter and supportscreens onto the top flange of the device andsecure the top flange to the ZHE body inaccordance with the manufacturer'sinstructions. Tighten all ZHE fittings andplace the device in the vertical position (gas

11873



inlet/outlet flange on the bottom). Do notattach the extract collection device to the topplate.

Note; If waste material (>1% of originalsample weight) has-obviously adhered to thecontainer used to transfer the sample to theZHE, determine the weight of this residueand subtract it from the sample weightdetermined in Step 9.4 to determine theweight of the waste sample that will befiltered.

Attach a gas line to the gas inlet/outletvalve (bottom flange) and, with the liquidinlet/outlet valve (top flange) open, beginapplying gentle pressure of 1-10 psi (or moreif necessary) to force all headspace slowlyout of the ZHE device into a hood. At the firstappearance of liquid from the liquid inlet/outlet valve, quickly close the valve anddiscontinue pressure. If filtration of the wasteat 4 °C reduces the amount of expressedliquid over what would be expressed at roomtemperature, then allow the sample to warmup to room temperature in the device before

filtering. If the waste is 100 percent solid (seeStep 7.1), slowly increase the pressure to amaximum of 50 psi to force most of theheadspace out of the device and proceed toStep 9.12.

9.9 Attach the evacuated pre-weighedfiltrate collection container to the liquidinlet/outlet valvq and open the valve. Beginapplying gentle pressure of 1-10 psi to forcethe liquid phase of the sample into the filtratecollection container. If no additional liquidhas passed through the filter in any 2-minuteinterval, slowly increase the pressure in 10-psi increments to a maximum of 50 psi. Aftereach incremental increase of 10 psi, if noadditional liquid has passed through the filterin any 2-minute interval, proceed to the next10-psi increment. When liquid flow hasceased such that continued pressure filtrationat 50 psi does not result in any additionalfiltrate within a 2-minute period, stop thefiltration. Close the liquid inlet/outlet valve,discontinue pressure to the piston, anddisconnect and weigh the filtrate collectioncontainer.

Note: Instantaneous application of highpressure can degrade the glass fiber filter andmay cause premature plugging.

9.10 The material in the ZHE is defined asthe solid phase of the waste and the filtrate isdefined as the liquid phase.

Note: Some wastes, such as oily wastesand some paint wastes' will obviouslycontain some material that appears to be aliquid. Even after applying pressure filtration,this material will not filter. If this is the case,the material within the filtration device isdefined as a solid and is carried through theTCLP extraction as a solid.

If the original waste contained <0.5percent dry solids (see Step 7.2), this filtrateis defined as the TCLP extract and isanalyzed directly. Proceed to Step 9.15.

9.11 The liquid phase may now be eitheranalyzed immediately (See Steps 9.13 through9.15) or stored at 4 °C under minimalheadspace conditions until time of analysis.Determine the weight of extraction fluid #1 toadd to the ZHE as follows:

Weight of extraction fluid =20x percent solids (Step 7.1) Xweight of waste filtered (Step 9.4 or 9.8)

9.12 The following steps detail how toadd the appropriate amount of extractionfluid to the solid material within the ZHE andagitation of the ZHE vessel. Extraction fluid#1 is used inall cases (See Step 5.6).

9.12.1 With the ZHE in the verticalposition, attach a line from the extractionfluid reservoir to the liquid inlet/outlet valve.The line used shall contain fresh extractionfluid and should be preflushed with fluid toeliminate any air pockets in the line. Releasegas pressure on the ZHE piston (from the gasinlet/outlet valve), open the liquid inlet/outlet valve, and begin transferring extractionfluid (by pumping or similar means) into theZHE. Continue pumping extraction fluid intothe ZHE until the appropriate amount of fluidhas been introduced into the device.

9.12.2 After the extraction fluid has beenadded, immediately close the liquid inlet/outlet valve and disconnect the extractionfluid line. Check the ZHE to ensure that allvalves are in their closed positions. Manuallyrotate the device in an end-over-end fashion2 or 3 times. Reposition the ZHE in thevertical position with the liquid inlet/outletvalve on top. Pressurize the ZHE to 5-10 psi(if necessary) and slowly open the liquidinlet/outlet valve to bleed out any headspace(into a hood) that may have been introduceddue to the addition of extraction fluid. This

bleeding shall be done quickly and shall bestopped at the first appearance of liquid fromthe valve. Re-pressurize the ZHE with 5-10psi and check all ZHE fittings to ensure thatthey are closed.

9.12.3 Place the ZHE in the rotaryagitation apparatus (if it is not already there)and rotate at 30+2 rpm for 18+2 hours.Ambient temperature (i.e., temperature ofroom in which extraction occurs) shall bemaintained at 22+3 °C during agitation.

9.13 Following the 18 +2 hour agitationperiod, check the pressure behind the ZHEpiston by quickly opening and closing the gasinlet/outlet valve and noting the escape ofgas. If the pressure has not been maintained(i.e., no gas release observed), the device isleaking. Check the ZHE for leaking asspecified in Step 4.2.1, and perform theextraction again with a new sample of waste.If the pressure within the device has beenmaintained, the material in the extractorvessel is once again separated into itscomponent liquid and solid phases. If thewaste contained an initial liquid phase, theliquid may be filtered directly into the samefiltrate collection container (i.e., TEDLAR5

bag) holding the initial liquid phase of thewaste. A separate filtrate collection containermust be used if combining would createmultiple phases, or there is not enough

volume left within the filtrate collectioncontainer. Filter through the glass fiber filter,using the ZHE device as discussed in Step9.9. All extract shall be filtered and collectedif the TEDLARR bag is used, if the extract ismultiphasic, or if the waste contained aninitial liquid phase (gee Steps 4.6 and 9.1).

Note: An in-line glass fiber filter may beused to filter the material within the ZHE if itis suspected that the glass fiber filter hasbeen ruptured.

9.14 If the original waste contained noinitial liquid phase, the filtered liquidmaterial obtained from step 9.13 is defined asthe TCLP extract. If the waste contained aninitial liquid phase, the filtered liquidmaterial obtained from Step 9.13 and theinitial liquid phase (Step 9.9) are collectivelydefined as the TCLP extract.

9.15 Following collection of the TCLPextract, immediately prepare the extract foranalysis and store with minimal headspace at4 °C until analyzed. Analyze the TCLP extractaccording to the appropriate analyticalmethods. If the individual phases are to beanalyzed separately (i.e., are not miscible),determine the volume of the individualphases (to 0.5%), conduct the appropriateanalyses, and combine the resultsmathematically by using a simple volume-weighted average:

(V,) (CO}+ (V) (C)Final analyte concentration

VI +V2



where:V, =The volume of the first phases (1).Ct =The concentration of the contaminant of

concern in the first phase (mg/i).V2 =The volume of the second phase (1).C2=The concentration of the contaminant of

concern in the second phase (mg/I).9.16 Compare the contaminant

concentrations in the TCLP extract with thethresholds identified in the appropriateregulations. Refer to section 10.0 for qualityassurance requirements.

10.0 Quality Assurance Requirements10.1 Maintain all data, including quality

assurance data, and keep it available forreference or inspection.

10.2 A minimum of one blatik (extractionfluid #1) for every 10 extractions that havebeen conducted in an extraction vessel shallbe employed as a check to determine if anymemory effects from the extractionequipment are occurring.

10.3 A matrix spike shall be performed foreach waste unless the result exceeds theregulatory level and the data is being usedsolely to demonstrate that the waste propertyexceeds the regulatory level. If more than onesample of the same waste is being tested, amatrix spike needs to be performed for everytwenty samples and the average percentrecovery applied to the wastecharacterization.

10.3.1 Matrix spikes are to be added afterfiltration of the TCLP extract and beforepreservation. Matrix spikes should not beadded prior to TCLP extraction of the sample.

10.3.2 Matrix spike levels should be madeat the appropriate regulatory threshold limits.However, if the extract contaminantconcentration is less than one half thethreshold limit, the spike level may be onehalf the contaminant concentration but notless than the quantitation limit or a fifth ofthe threshold limit.

10.3.3 The purpose of the matrix spike isto monitor the adequacy of the analytical

methods used on the TCLP extract and todetermine whether matrix interferences existin analyte detection. If the matrix spikerecoveries are less than 50%, then theanalytical methods are not performingadequately or use of the methods isinadequate. Use of internal calibrationquantitation methods, modification of theanalytical methods, or use of alternateanalytical methods may be needed toaccurately measure the contaminantconcentration in the TCLP extract.

10.3.4 Use of internal quantitationmethods is also required when thecontaminant concentration is within 20% ofthe regulatory level. (See section 10.5concerning the use of internal calibrationmethods.)

10.3.5 Matrix spike recoveries arecalculated by the following formula:

A-BPercent recovery = x 100%

C

where A= the concentration of the spikedsample,

B =the concentration of the unspikedsample, and

C=the spike level10.4 All quality control measures

described in the appropriate analyticalmethods shall be followed.

10.5 The use of internal calibrationquantitation methods shall be employed for acontaminant if: (1) Rec~very of thecontaminant from the TCLP extract is not atleast 50% and the concentration does notexceed the regulatory level, and (2) Theconcentration of the contaminant measuredin the extract is within 20% of the appropriateregulatory level.

10.5.1 The method of standard additionsshall be employed as the internal calibration

quantitation method for each metalliccontaminant. -

10.5.1.1 The method of standard additionsrequires preparing calibration standards inthe sample matrix rather than reagent wateror blank solution. It requires taking fouridentical aliquots of the solution and addingknown amounts of standard to three of thesealiquots. The fourth aliquot is the unknown.Preferably, the first addition should beprepared so that the resulting concentrationis approximately 50% of the expectedconcentration of the sample. The second andthird additions should be prepared so that theconcentrations are approximately 100% and150% of the expected concentration of thesample. All four aliquots are maintained atthe same final volume by adding reagentwater or a blank solution, and may needdilution adjustment to maintain the signals inthe linear range of the instrumentaltechnique. All four aliquots are analyzed.

.10.5.1.2 Prepare a plot, or subject data tolinear regression, of instrumental signals orexternal-calibration-derived concentrationsas the dependent variable (y-axis) versusconcentrations of the additions of standardas the independent variable (x-axis). Solvefor the intercept of the abscissa (theindependent variable, x-axis) which is theconcentration in the unknown.

10.5.1.3 Alternately, subtract theinstrumental signal or external-calibration-derived concentration of the unknown(unspiked) sample from the instrumentalsignals or external-calibration-derivedconcentrations of the standard additions. Plotor subject data to linear regression of thecorrected instrumental signals or external-calibration-derived concentrations as thedependent variable versus the independentvariable. Derive concentrations for unknownsusing the internal calibration curve as if itwere an external calibration curve.

10.6 Samples must undergo TCLPextraction within the following time periods:

SAMPLE MAXIMUM HOLDING TIMES

[Days]

From: From: From:

Field collection TCLP extraction Preparative extraction Total elapsed timeTo: To: To:

TCLP extraction Preparative extraction Determinative analysis

Volatiles .............................................................................. 14 NA 14 28Semi-volatiles .................................................................... 7 7 40 54Mercury ............................................................................... 28 NA 28 56Metals, except mercury .................................. 180 NA 180 360

NA = Not applicable.

If sample holding times are exceeded, thevalues obtained will be considered minimalconcentrations. Exceeding the holding time isnot acceptable in establishing that a wastedoes not exceed the regulatory level.Exceeding the holding time will notinvalidate characterization if the wasteexceeds the regulatory level.

PART 264-STANDARDS FOROWNERS AND OPERATORS OFHAZARDOUS WASTE TREATMENT,STORAGE, AND DISPOSALFACILITIES


Authority: 42 U.S.C. 6905, 6912, 6924, and6925.

8. Section 264.301 is amended byrevising paragraph (e)(1] to read asfollows:

§ 264.301 Design and operatingrequirements.

1187511875


11876 Federal Register/ Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations

(e) * * *

(1) The monofill contains onlyhazardous wastes from foundry furnaceemission controls or metal castingmolding sand. and such wastes do notcontain constituents which wouldrender the wastes hazardous for reasonsother than the Toxicity Characteristic in§ 261.24 of this chapter, with EPAHazardous Waste Numbers D004through D017; and* * • a *

PART 265-INTERIM STATUSSTANDARDS FOR OWNERS ANDOPERATORS OF HAZARDOUS WASTETREATMENT STORAGE, ANDDISPOSAL FACILITIES

9. The authority citation of part 265continues to read as follows:

Authority: 42 U.S.C. 6905. 6912(a). 6924.6925, and 6935.

10. Section 265.221 is amended byrevising paragraph (d)(1 to read asfollows:

§ 265.221 Design requirements.(* ) a a

(d] * a *

- (1) The monofill contains onlyhazardous wastes from foundry furnaceemission controls or metal castingmolding sand, and such wastes do notcontain constituents which wouldrender the wastes hazardous for reasonsother than the Toxicity Characteristic in§ 261.24 of this chapter, with EPAHazardous Waste Numbers D004through D017; and• • * * *

11. Section 265.273 is amended byrevising paragraph (a) to read asfollows:

§ 265.273 Waste analysis.• * * * •

(a) Determine the concentrations inthe waste of any substances whichequal or exceed the maximumconcentrations contained in Table 1 of§ 261.24 of this chapter that cause awaste to exhibit the ToxicityCharacteristic;* • * * *

PART 268--LAND DISPOSALRESTRICTIONS


Authority: 42 U.S.C. 6905, 6912(a), 6921, and6924.

13. -Appendix I of part 268 is revised toread as follows:

Appendix I-Toxicity CharacteristicLeaching Procedure (TCLP)

Note: The TCLP is published in Appendix 11of part 261.

PART 271-REQUIREMENTS FORAUTHORIZATION OF STATEHAZARDOUS WASTE PROGRAMS

14. The authority 6itation for part 271continues to read as follows:

Authority: 42 U.S.C. 6905, 6912(a), and 6926.

15. Section 271.1, paragraph {j), theheading of Table 1 is republished, andTable I is amended by adding thefollowing entry in chronological orderby date of promulgation to read asfollows:

§ 271.1 Purpose and scope.

(j) *

TABLE 1.-REGULATIONS IMPLEMENTING THE HAZARDOUS AND SOLID WASTE AMENDMENTS OF 1984

Promulgation date Title of regulation Federal Register reference Effective date

March 29, 1990 . .................... Toxicity characteristic ............................... [Insert FR reference on date of publi- September 25, 1990cation].

PART 302-DESIGNATION, Authority- 42 U.S.C. 9602; 33 U.S.C. 1321 Wastes Characteristics:" and byREPORTABLE QUANTITIES, AND and 1361. revising the entry "Characteristic of EPNOTIFICATION 17. Section 302.4 is amended by Toxicity" and its sub entries to read as

17. ectin 32.4 s aende byfollows:16. The authority citation for part 302 revising under the column Hazardous

continues to read as follows: Substance the entry "Unlisted § 302.4 Designation of hazardousHazardous Wastes Characteristic of EP substances.Toxicity" to read "Unlisted Hazardous * * • * •

TABLE 302.4.-LIST OF HAZARDOUS SUBSTANCES AND REPORTABLE QUANTITIES

Statutory Final RO

Hazardous substance CASRN Regulatory synonyms RCRARQ Codet waste Category Pounds (Kg)

number

Characteristic of Toxicity.Arsenic (D004) ..........................................Barium (D005) .......................Benzene (D018).... ......................Cadmium (006) ...................................Carbon tetrachloride (D019) .................Chlordane (D020) .....................................Chlorobenzene (D021) .............................Chloroform (022)Chromium (0007) ...............................o-Cresol (D023) ........................................m-Cresol (D024) .......................................

.1 4

.1 41000 1,2,3,4

.1 45,000 1,2,4

1 1,2,4100 1,2,4

5,000 1,2,4.1 4

1,000 1,41,000 1,4

1 (0.454)1,000 (454)

10 (4.54)10 (4.54)10 (4.54)1 (0.454)

100 (45.4)10 (4.54)10 (4.54)

1,000 (454)1,000 (454)

.....................

........................... I ..............................................

................................. .... .................................

.................................................... ...... .......

........................... I ..............................................

......................................................................

.......................... ............... ...............................

........................... I .... ............. ....... ..

.........................................................................

................................................................ I .........


Federal Register I Vol. 55, No. 61 / Thursday, March 29, 1990 / Rules and Regulations 11877

TABLE 302.4.-LIST OF HAZARDOUS SUBSTANCES AND REPORTABLE QUANTITIES-Continued

Statutory Final RO

Hazardous substance CASRN Regulatory synonyms RCRARO Codet waste Category Pounds (Kg)

number

p-Cresol (D025) ................ N.A.. .................... a .................................................... 1,000 1, 4 1025 C 1,000 (454)Cresol (D026) .................. N.A.. ........................................................................ 1,000 1. 4 D026 C 1,000 (454)2,4-D (Dols) .............................................. N.A. . ................................................. 100 1, 4 D016 B 100 (45.4)1,4-Dichlorobenzene (D027) ................... N.A . .......................................................................... 100 1, 2,4 D027 B 100 (45.4)1.2-Dichloroethane (D028) ...................... N.A . .......................................................................... 5,000 1, 2,4 D028 B 100 (45.4)1,1-Dichloroethylene (DO29) .................... N.A .......................................................................... 5,000 1, 2, 4 D029 B 100 (45.4)2,4-Dinitrotoluene (D030) ......................... N.A .......................................................................... 1,000 1, 2, 4 D030 A 10 (4.54)Endrin (D012) .................. N.A.. ..................................................................... 1 1,4 D012 X 1 (0.454)Heptachlor (and hydroxide) (D031) . N.A . .......................................................................... 1 1, 2, 4 D031 X 1 (0.454)Hexachlorobertzene (D032) ..................... N.A. . . ........................................................................ . 1 2,4 D032 A 10 (4.54)Hexachlorobutadiene (D033) .................. N.A . ......................................................................... . 1 2, 4 D033 X 1 (0.454)Hexachloroethane (D034) ....................... N.A . ......................................................................... .1 2, 4 D034 6 100 (45.4)Lead (D008) ................... N.A. . ........................... ................................... . .. 1 4 D008 (#)Lindane (D013) ................. N.A.. .......................................................................... 1 1,4 D013 X 1 (0.454)Mercury (D009) ......................................... N.A . ......................................................................... .1 4 D009 X 1 (0.454)Methoxychlor (D014) ....... ...... NA........................................ 1 .1, 4 D014 X 1 (0.454)Methyl ethyl ketone (D035) ..................... N.A . ......................................................................... . 1 4 D035 D 5,000 (2270)Nitrobenzene (D036) ............. N.A.. ....................................................................... .1.000 1, 2, 4 D036 C 1,000 (454)Pentachlorophenol (D037) ....................... N.A .......................................................................... 10 1, 2, 4 D037 A 10 (4.54)Pyridine (D038) ......................................... N.A .......................................................................... .1 4 D038 C 1,000 (454)Selenium (D010) ................ N.A. . ......................................................................... .1 4 D010 A 10 (4.54)Silver (D011) ............................................. N.A. . .. ................................... .1 4 D011 X 1 (0.454)Tetrachloroethylene (D039) ..................... N.A . ......................................................................... .1 2, 4 1039 B 100 (45.4)Toxaphene (D015) .............. N.A. . ......................................................................... 1 1, 4 D015 X 1 (0.454)Thrichloroethylene (D040) ....................... N.A .......................................................................... 1000 1, 2. 4 D040 B '100 (45.4)2,4,5-Trichloroethylene (D041) ................ N.A.. ........................................................................ 10 1, 4 041, A 10 (4.54)2.4,6-Trichlorophenol (D042) .................. N.A .......................................................................... 10 1, 2,4 D042 A 10 (4.54)2,4,5-TP (D017) ......................................... NA.. .. ................................... 100 1, 4 D017 B 100 (45.4)Vinyl chloride (12043) ................ N.A. . .................................................................. ...... . 1 2, 3. 4 D043 X 1 (0.454)

f-indicates the statutory source as defined by 1, 2, 3, or 4 below.* 1-indicates that the 1-pound RO is a CERCLA statutory RQ.#-indicates that the RQ is subject to change when the assessment of potential carcinogenicity is completed.

[FR Doc. 90-6104 Filed 3-28-90; 8:45 am]

BILLING CODE 6560-50-M


29, 1990 environmental protection 5. 1.€¦ · a. definition of hazardous waste subtitle c of the...

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