second five year review report

SDMS DocID 2010801

SECOND FIVE-YEAR REVIEW REPORT

Delaware City PVC Plant S te

New Castle County, Delaw, re

Prepared by:

U.S. Environmental Protection Agei y

Region III

Philadelphia, Pennsylvania

Abraham Ferdas, Director DateHazardous Site Cleanup Division

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• Table of Contents\

List of Acronyms , jv

Executive Summary ."! _ vi

Five-Year Review Summary Form „ vii

I. Introduction 1

II. Site Chronology 2Table 1 - Chronology of Site Events 2

III. Background 4Physical Characteristics 4Land and Resource Use '. 5Hi story of Contamination 5Initial Response Activities 6Basis for Taking Action 7

IV. Remedial Actions 7Remedy Selection 8Remedy Implementation 9Systems Operations/Operation and Maintenance (O&M) 11

V. Progress Since the Last Five-Year Review 1 1

VI. Five-Year Review Process 12Administrative Components 12Community Involvement 12Interviews 13Document Review 14Data Compilation Review 14Site Inspections 15

VII. Technical Assessment 16Question A: Is the remedy functioning as intended by the decision documents? 16Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedialaction objectives (RAOs) used at the time of the remedy selection still valid? 16Remedial Action Objectives 16Changes in Standards and To Be Considereds 16Changes in Exposure Pathways, Toxicity, and Other Contaminant Characteristics 17

Delaware City PVC Plant SiteSecond Five-Year ReviewSeptember 2004

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Question C: Has any other information come to light that could call into question theprotectiveness of the remedy? 18Technical Assessment Summary 20

VIII. Issues '. 20

IX. Recommendations and Follow-up Actions 20

X. Statement on Protectiveness 21

XI. Next Review 22

Attachments 22Attachment 1 - Site LocationAttachment 2 - Maps Depicting Locations of Contaminant Plume

1990-2004Attachment 3 - List of Documents ReviewedAttachment 4 - List of Potential ARARs and To Be Considereds


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AOC

ARAR

CERCLA

CFR

DEODW

DNREC

EDC

EPA

GCS

MCL

NCP

NPDES

NPL

O&M

OU

PVC

RA

RAO

RI/FS

ROD

RPM

RV


List of Acronyms

Administrative Order on Consent

Applicable or Relevant and Appropriate Requirement/

Comprehensive Environmental Response, Compensation and Liability Act

Code of Federal Regulations

Office of Drinking Water (State of Delaware)

Department of Natural Resources and Environmental Control(State of Delaware)

Ethylene Dichloride (1,2-Dichloroethane; 1.2DCA)

U.S. Environmental Protection Agency

Ground Water Collection System

Maximum Contaminant Level

National Contingency Plan

National Pollutant Discharge Elimination System

National Priorities List

Operation and Maintenance

Operable Unit

Polyvinyl Chloride

Remedial Action

Remedial Action Objective

Remedial Investigation/Feasibility Study

Record of Deci sion

Remedial Project Manager

Reservoir

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SARA Superfund Amendments and Reauthorization Act

SDWA Safe Drinking Water Act

TCE Trichloroethylenei

VOC Volatile Organic Compound

VCM Vinyl Chloride Monomer (Vinyl Chloride; VC)

WWTP Waste Water Treatment Plant

Delaware City PVC Plant SiteSecond Five-Year Review

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Executive Summary

The Delaware City PVC Plant Site ("PVC Site" or "Site") is located approximately twomiles northwest of Delaware City, New Castle County, Delaware. The Site originated from apolyvinyl chloride ("PVC") manufacturing facility that contaminated area soils and ground water.with PVC sludges and volatile organic compounds ("VOCs"). In May 1984, EPA and theDelaware Department of Natural Resources and Environmental Control ("DNRJEC") entered intoa Consent Order with Stauffer and Formosa to perform a Feasibility Study (FS) and to implementan approved Remedial Action (RA). EPA issued a Record of Decision ("ROD") in 1986. Theremedy described in the ROD included:

• excavation of PVC sludge and contaminated soils from the three off-gradematerial batch pits, two aeration basins, and stormwater retention pond;

• lining of the three off-grade batch pits, two aeration basins, stormwater retentionpond, and two unlined ditches;

• capping of the closed buried sludge pits and the former PVC storage area;

• capture of the ground water and treatment in Formosa's plant; and

• operation and maintenance of the caps and ground water recovery system.

Most of these activities were completed by 1992 with the construction completionmilestone attained in 2001. Overall the Site is protective of human health and the environment inthe short-term but not the long-term because of the issues discussed below.

Remedial actions at the plant have removed the source of ground water contamination,and the ground water extraction and treatment system continues to operate as designed and isexpected to achieve the cleanup standards specified in the ROD in approximately 20 years.However, EPA and the State of Delaware are currently investigating the source of a potentiallysite-related contaminant, ethylene dichloride ("EDC"), found in the drinking water well of agasoline filling station near the Site in February 2004. While there is no one currently drinkingfrom this well, if the EDC is determined to be from the Site, the remedy would not be protectivein the long-term.

Vapor intrusion into structures above the VOC-contaminated ground water plume mayalso call into question the protectiveness of the remedy. EPA plans to further evaluate this issueand discuss this issue with Formosa, Zeneca and other owners/occupants of buildings that may belocated above the contaminated ground water plume where vapor intrusion may pose a potentialrisk.

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Five-Year Review Summary Form

Site name: Delaware City PVC Plant

SITE IDENTIFICATION

EPAID:DED980551667

Region: 3 State: DE City/County: New Castle County

SITE STATUS

NPL status: /Final G Deleted G Other (specify).

Remediation Status (choose all that apply): G Under Construction S Operating G Complete

Multiple OUs?* «/YES Q NO Construction completion date: September 25. 2001

Has site been put into reuse? G YES G NO / NA (On-going active facility)

REVIEW STATUS

Lead agency: S EPA G State Q Tribe G Other Federal Agency.

Author name: Frederick N. Mac Millan

Author title: Remedial Project Manager Author Affiliation: U.S. EPA - Region 3

Review period: December 22,2003 - September, 20O4

Date(s) of site inspection: March 18,2004

Type of review: G Post-SARA / Pre-SARA

G Non-NPL Remedial Action Site

G Regional Discretion

G NPL-Removal only

G NPL State/Tribe-lead

^ Kegionai Discretion

Review number: G 1 (first) «/ 2 (second) G 3 (third) G Other(specify)_

Triggering action:Triggering action:G Actual RA Onsite Construction at Site OU G Actual RA Start at OU#

G Construction Completion v Previous Five-Year Review Report

G Other (specify) Informed public review would be conducted

Triggering action date: March 23,1999

Due date (five years after triggering action date): March 23, 2004

* ("OU" refers to operable unit)

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Five-Year Review Summary Form, cont'd.

Issues:

1) EPA and the State of Delaware are currently investigating the source of a potentially site-related contaminant, ethylene dichloride ("EDC"), found in the drinking water well of agasoline filling station near the Site in February 2004.

2) Ground water contamination by volatile organic compounds (VOCs) may give rise tovapor intrusion into structures above the contaminated ground water plume.

Recommendations and Follow-up Actions:

1) EPA and the State will continue a revised ground water study to determine if the EDC issite-related. If so, further remedial measures will be evaluated. The State has alreadynotified the gasoline station owner regarding the presence of contaminated water in theirdrinking water well and has required the gasoline station to notify potential water users.In the meantime, Zeneca is providing an alternate source of potable water for the gasolinestation.

2) EPA will contact the owners/occupants of buildings that may be located above thecontaminated ground water plume and will evaluate whether or not a detailed study isnecessary.

Protectiveness Statements:

The remedy for OU 1 is fully protective. The remedy has effectively reduced and/oreliminated the sources of site-related contaminants to ground water. These actions included theexcavation and removal of sludges from various surface impoundments, capping of closed areas,the installation of liners and leachate detection in basins used in process operations.

The remedy for OU 2 is currently protective in the short-term but may not be protective inthe long-term. The remedy currently protects human health and the environment by effectivelyreducing the migration of Site-related contaminants in ground water, by capturing and removingthem from ground water, and by eliminating them through treatment. These measures havereduced the risk of exposure to Site contaminants and will continue until ground water cleanupstandards are achieved. Current estimates call for completion of the ground water remedy at theSite to take another 20 years. EPA will continue to monitor these trends following this five-yearreview.

The OU 2 remedy may not be protective in the long-term depending on the outcome ofthe investigation to determine the source and the nature of the contamination in the Getty gasstation well. The drinking water well, installed there in 1987 as part of the remedial action underOU 2 as specified in the 1986 ROD, was found to be contaminated with EDC, one of thecontaminants of concern at the Site. This and other area wells were sampled under EPA

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oversight on May 12, 2004. In the meantime, an alternate potable water source has beenprovided and plans are being made to tie-in the gasoline station to the municipal water supply ifnecessary. If the EDC is site-related, additional remedial measures will be evaluated.

Vapor intrusion into structures above the VOC-contaminated ground water plume mayalso call into question the protectiveness of the OU 2 remedy. EPA plans to further evaluate thisissue and discuss this issue with Formosa, Zeneca and other owners/occupants of buildings thatmay be located above the contaminated ground water plume where vapor intrusion may pose apotential risk.

Overall the Site is protective of human health and the environment in the short-term butmay not be in the long-term because of the issues discussed above for OU 2.


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Delaware City PVC Plant Superfund SiteNew Castle County, Delaware

Second Five-Year Review Report

I. Introduction

The purpose of five-year reviews is to determine whether the remedy at a site is protectweof human health and the environment. The methods, findings, and conclusions of reviews aredocumented in Five-Year Review ("FYR") reports. In addition, Five-Year Review reportsidentify issues found during the review, if any, and recommendations to address them.

EPA guidance on conducting five-year reviews is provided by OSWER Directive 9355.7-03B-P, Comprehensive Five-Year Review Guidance (EPA, 2001). EPA personnel followed theguidance provided in this OSWER directive in conducting the five-year review for the Site.

Five-year reviews are conducted either to meet the statutory mandate under theComprehensive Environmental Response, Compensation, and Liability Act (CERCLA) § 121, oras a matter of EPA policy. The statutory requirement to conduct a five-year review was added toCERCLA as part of the Superfund Amendments and Reauthorization Act of 1986 (SARA).CERCLA §121 states:

If the President selects a remedial action that results in any hazardoussubstances, pollutants, or contaminants remaining at the site, the President shallreview such remedial action no less often than each five years after the initiationof such remedial action to assure that human health and the environment arebeing protected by the remedial action being implemented. In addition, if uponsuch review it is the judgement of the President that action is appropriate at suchsite in accordance with section [104] or [106], the President shall take or requiresuch action. The President shall report to the Congress a list of facilities forwhich such review is required, the results of all such reviews, and any actionstaken as a result of such reviews.

The Agency interpreted this requirement further in the NCP; 40 CFR §300.430(f)(4Xh)states:

If a remedial action is selected that results in hazardous substances, pollutants, orcontaminants remaining at the site above levels that allow for unlimited use andunrestricted exposure, the lead agency shall review such action no less often thanevery five years after the initiation of the selected remedial action.

The statutory requirement to conduct a five-year review applies to CERCLA §121remedial actions selected after the effective date of SARA (October 17, 1986). For sites where astatutory review is not specifically required, reviews may be conducted as a matter of policy forany of the following type actions:


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1.

2.

3.

A pre-SARA remedial action that leaves hazardous substances, pollutants, orcontaminants above levels that allow for unlimited use or unrestricted exposure.

A pre- or post-SARA remedial action that, upon completion, will not leave hazardoussubstances, pollutants'or contaminants above levels that allow for unlimited use orunrestricted exposure, but will take longer than five years to complete, i.e., achieve thecleanup levels that allow for unlimited use and unrestricted exposure.

A removal action for a site on the NPL that leaves hazardous substances, pollutants, orcontaminants above levels that allow for unlimited use or unrestricted exposure, andwhere no remedial action has or will take place.

The pre-SARA remedial action described above (item 1) corresponds to the remedyspecified for the Delaware City PVC Plant Site; therefore, EPA Region ID has conducted thisfive-year review of the remedy implemented at the Site in New Castle County, Delaware as amatter of policy due to the fact that hazardous substances, pollutants, or contaminants remain atthe Site above levels that allow for unlimited use and unrestricted exposure.

This is the second five-year review for the Delaware City PVC Site. The triggeringaction for this policy review is the first five year review completed on March 23, 1999. Thisreview was conducted for the entire site by the Remedial Project Manager (RPM) from March2003 through September 2004. This report documents the results of the review.

II. Site Chronology

Table 1 lists the chronology of events for the PVC Site.

Table 1: Chronology of Site Events

Date

1966

Late 1960s and1970s

May 1981

October 23, 1981

Event

Stauffer Chemical Company ("Stauffer," now AstraZenecaPharmaceuticals LP ("Zeneca")) begins manufacture of polyvinylchloride ("PVC") resin from vinyl chloride monomer ("VCM") at theSite.

Off-grade PVC resins, sludges from wastewater treatment system andresidues from plant processes are disposed in buried sludge pits, whichare closed and covered.

Stauffer sells the PVC plant to Formosa Plastics Corporation ofDelaware ("Formosa") but keeps the area outside of the PVC plant.Formosa continues operations of the PVC plant to present.

PVC Plant placed on Interim National Priorities List ("NPL").

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Date

October 18, 1982

December 20,1983

May 23, 1984

September 30,1986

April 28, 1987

March 3 1,1988

September 29,1989

September 1 8,1991

April 6, 1992

April 30, 1992

June 30, 1992

June 30, 1995

December 12,1995

March 23, 1999

October 25, 2000

Event

PRP-led investigation confirms ground water contaminated with vinylchloride monomer ("VCM"), ethylene dichloride ("EDC") andtrichloroethene ("TCE").

Delaware City PVC Plant Site is placed on the final NPL.

Stauffer and Formosa agree under an Administrative Order on Consent("AOC") to complete remedial investigation and perform all necessaryremediation under EPA oversight.

EPA issues Record of Decision ("ROD"). Formosa and Stauffer dividethe work. Formosa was responsible for the remedial actions on the PVCplant property ("OU 1"), Stauffer was responsible for remedial actionsoff of the PVC Plant property ("OU 2"). RA onsite construction (PVCsludge removal) at OU 1 begins.

AOC amended, Remedial Design Starts for OU 1 and OU 2.

Remedial Design completed, Remedial Action begins - OU 1 .

Remedial Design completed, Remedial Action starts - OU 2.

EPA issues Explanation of Significant Differences (ESD) for OU 1 andOU 2 for installation of above ground storage tank to replace 3 ponds(OU 1) and air stripper to treat ground water instead of using the existingWaste Water Treatment Plant (OU 2).

Interim Remedial Action Report, OU 2.

Workplan completed for revised RI/FS to address additional groundwater contamination migrating offsite from eastern portion of the Siteand additional soil contamination from buried PVC resins.

Remedial Action Report, OU 1 .

Begin investigation of additional ground water contamination migratingfrom eastern portion of the Site.

Begin investigation to address additional soil contamination from buriedPVC resins.

First five-year review completed

Additional capture wells under OU 2 installed.


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Date

February 29, 2000

March 8, 2001

July 26, 2001

September 25,2001

June 14, 2002

June 14, 2002

August 30, 2002

August 22, 2003

Event

Investigation completed for additional ground water contaminationmigrating from eastern portion of the Site.

Remedial Design for additional ground water contamination begins,activities combined into OU 2.

OU 2 Interim Remedial Action construction starts.

OU 2 Interim Remedial Action construction completed.

Investigation for additional soil contamination from buried PVC resinscompleted; any future related activities to be part of OU 1 .

OU 2 Interim Remedial Action report completed.

2002 PRP Ground Water Interceptor System Performance MonitoringReport submitted to EPA.

2003 PRP Ground Water Interceptor System Performance MonitoringReport submitted to EPA.

III. Background

Physical Characteristics

The Delaware City PVC Plant Site ("PVC" Site) is located approximately two milesnorthwest of Delaware City, Delaware ("DE") at latitude 39°35'16" North and longitude75°39'50" West in New Castle County, DE. It is situated east of State Route 13 and just west ofthe VPI Mirrex Corporation (formerly American Mirrex Co.) and the Motiva Enterprises(formerly Star Enterprise Oil Refinery), between Red Lion Creek to the north, and Dragon Creekto the south (See Attachment 1). The Site, according to the ROD, is approximately 260 acres insize. However, during remedial action the contaminated ground water plume beneath thewestern portion of the Site ("western plume") was discovered to extend further north and souththen expected. This increased the Site to .approximately 400 acres in size. Since the last five-year review in 1999, the area of the plume of contaminated ground water beneath the westernportion of the Site has diminished significantly.

The Site consists of a polyvinyl chloride (PVC) production facility owned and operatedby Formosa Plastics Corporation (Formosa) and adjacent land owned by others under whichcontaminated ground water flows. The land to the east of the Site is primarily industrial; the landto the west of the site is farmland with some housing developments as is land south of the Site.Land to the north of the Site has some industry and rail lines, but is largely undeveloped.Originally the plant contained a number of unlined earthen lagoons, ditches and sludge pits

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where off-grade PVC production resins and process wastes were collected. Wastewater and PVCsolids were treated in concrete-lined, aerated lagoons that were found to be cracked and potentialsources of contamination. The storm water reservoir pond was an unlined, earthen basin thatalso received process wastewater and PVC solids from the production area.

Land and Resource Use

The Site is bordered by several industrial facilities, Akzo Nobel and VPI MirrexCorporation to the north and east respectively. Further east and southeast of the Site is theMotiva Refinery (formerly Star Enterprise Oil Refinery). The Site is generally bordered on thesouth by Wrangle Hill Road and on the west by U.S. Route 13 (South Dupont Highway) andfurther south and west by Delaware State Route 1. The Site terrain is generally flat. The Plantarea itself sits atop a ground water divide that causes ground water (and subsequently groundwater contaminants) to flow in all directions from beneath the PVC Plant. The western portion ofthe contaminant plume moves north and south likely under the influence of a buried streamchannel.

There is some business but little residential development in the immediate Site area.Additional residential development is present on the outskirts of the Site, primarily along Route13 and west. Several of these residences are downgradient (south) from the direction of flow ofthe western portion of the contaminated ground water plume and use ground water as theirprimary source of drinking water.

History of Contamination

Stauffer Chemical Company built a carbon disulfide ("CS2") production plant aroundI960, followed by a PVC production plant in 1966. Several impoundments were constructed aspart of the PVC plant. Two of the impoundments were concrete-lined aeration basins, three wereearthen lagoons (off-grade batch pits) used to dump off-grade PVC. One was used to collectstormwater and any chemical or oil spills from the PVC plant. This same pond also occasionallycollected process wastewater. The Site had two earthen ditches which carried water and awater/PVC suspension to the off-grade batch pits and the stormwater reservoir. When necessary,PVC sludge was removed from all of the impoundments and buried on the north side of theaeration basins. In 1978 this burial area was capped with a PVC membrane and earthen cap. Inan area west of the CS2 plant and north of the PVC plant, PVC resin was stored in a mound. By1972, storage was discontinued in this area, but PVC resin remained in the soil. Resin from thispile spread to a wetlands area to the north of resin storage area. The resin also extended to anarea of stressed vegetation northeast of the wetlands that also contains waste sulfur from the CS2

plant. North of the wetlands and the stressed vegetation area is a burial area for the CS2 plantthat had previously been capped with a plastic liner and soil.

From 1966 until May 1981, Stauffer Chemical Company (Stauffer) operated the PVCresin production plant and the CS2 production plant at the Site. Stauffer manufactured polyvinylchloride ("PVC") resin from vinyl chloride monomer ("VCM") at the Site. In May 1981,Stauffer Chemical Company conveyed to Formosa the PVC production plant but retained


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ownership of the CS2 plant and kept the area outside of the PVC plant. Formosa has continued tooperate the PVC plant to the present day. In April 1982, one of the domestic supply wells onStauffer's property was found to be contaminated with 1,2-dichloroethane (or ethylenedichloride, "EDC"), VCM, and trichloroethylene ("TCE"). This prompted Formosa and Staufferto perform a hydrogeologic investigation which identified a plume of EDC, VCM, and TCE inthe lower portion of the Columbia aquifer, underneath and west of the PVC plant. Furtherinvestigation determined that the sources of the ground water contamination from the PVC plantwere two unlined ditches, three off-grade batch pits, two aeration basins, and a stormwaterreservoir ("RV") pond. The sources outside of the PVC plant were closed buried sludge pits anda former PVC storage area. Ground water sampling conducted in March 1982 and April 1983confirmed that high concentrations of site-related contaminants had impacted nearby residentialwells. Concentrations of VCM ranging from 19 parts per billion ("ppb") to 220 ppb and EDCranging from 490 ppb to 2,900 ppb were found in private well water supplies. See Attachment 2for various depictions of the ground water plume.

Initial Response Activities

The Site was included on the Interim Priorities List in October 1981, proposed forinclusion on the National Priorities List in December 1982, and finalized on September 8, 1983,as published in the Federal Register, 48 Fed. Reg. 40658.

In March 1982, samples from monitoring wells located in the vicinity of the off-gradebatch pits and the PVC burial area documented the presence of VCM, EDC, and TCE in theground water (Sampling Inspection Report, Ecology & Environment, Inc.). Monitoring Well 8had EDC at 13,000 ppb and TCE at 15 ppb and Monitoring Well 9 had VCM at 370 ppb.Sampling in April 1982 showed that the contaminants had polluted a residential ground waterwell adjacent to the Site with VCM at 605 ppb, EDC at 4,500 ppb and TCE at 12 ppb.Subsequent samples obtained in March 1983 showed that the contaminants had migrated in theground water and impacted two additional private well water supplies. Concentrations of VCMranging from 19 ppb to 220 ppb and EDC ranging from 490 ppb to 2,900 ppb were found inthose private well water supplies.

In 1984 EPA, DNREC, Stauffer Chemical and Formosa Plastics Corporation signed anAdministrative Order on Consent (Docket No. m-84-6-DC) in which it was agreed that Staufferand Formosa would perform a feasibility study and carry out any remedial action as determinedby EPA. Stauffer Chemical Company submitted a Feasibility Study to EPA which was approvedon July 15,1986. This study outlined alternatives for remediating this Site.


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Basis for Taking Action

Contaminants

Hazardous-substances that nave been released at the Site in each media include:

Ground Water Soils1,2-Dichloroethane (EDC) 1,2-Dichloroethane (EDC)Trichloroethylene (TCE) Trichloroethylene (TCE)Vinyl Chloride Monomer (VCM) Vinyl Chloride Monomer (VCM)

Potential human exposure pathways for Site contaminants evaluated in the riskassessment included inhalation of volatilized contaminants from unlined ditches, pits, ponds andlagoons. This was determined to be an insignificant pathway at the time of the ROD. Direct andindirect contact with soils, especially PVC sludges contaminated with EDC, VCM and TCE wereconsidered the most significant direct dermal pathway, but also the least likely due to workerprotective controls and robust plant controls. Direct contact with onsite PVC sludges, resultingin dermal contact, inhalation and ingestion of ground water contaminated with EDC, VCM andTCE constituted the greatest potential human health threat. A hydraulic connection betweenground water and the Red Lion Creek and Dragon Run, both used for recreation and drinkingwater represented a potential surface water exposure pathway.

Future potential environmental receptors of Site contaminants included aquatic andterrestrial bioreceptors, but there was little information on the actual communities present in thisprimarily industrial/rural area. The primary pathway would be the contamination of surfacewater via ground water. The persistence of Site contaminants in surface waters would be limitedby volatilization and none of these compounds has a high potential for bioaccumulation orbiomagnification in aquatic or terrestrial biota. The risk associated cleanup standards for groundwater in the 1986 ROD were as follows:

EDC - 0.94 Micrograms per liter ("ug/L")*VCM - 1 ug/LTCE-2.7 ug/L

*(NB: ug/L is equivalent to parts per billion ("ppb"))

IV. Remedial Actions

The Remedial Action Objectives for the Site, though not precisely stated in the ROD,included the abatement of sources of contamination and the mitigation of the existing plume ofcontaminated ground water. This would involve a) preventing or reducing infiltration ofcontaminants through their sources, b) preventing or reducing migration of Site-relatedcontaminants in ground water (contaminant plumes), c) preventing direct contact of the soil with


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PVC resins, d) preventing future degradation of ground water and/or surface waters by sitecontaminants, and e) preventing exposure to contaminated ground water via residential wells.

Remedy Selection

EPA approved an initiative by Formosa and Stauffer to divide the work at the Site andperform the remedial action activities as operable units ("OUs") under EPA oversight. TheDelaware City PVC Plant Site was originally divided into operable units as follows:

September 30. 1986 ROD

-OU 1 (Actions on PVC Plant Property)-OU 2 (Actions off PVC Plant Property)

Formosa was responsible for the remedial actions on the PVC plant property (i.e."OU 1")which included:

Off-grade Batch Pits, Storm Water Reservoir and Unlined Ditches-Excavate and remove existing PVC sludges and contaminated soils; install a double syntheticliner, monitoring wells and perform quarterly sample analysis for TCE, EDC and VCM.

Aerated Lagoons-Excavate and remove PVC sludges, clean and repair lagoons as necessary, install a doublesynthetic liner and monitoring wells, and perform quarterly sampling analysis for TCE, EDCand VCM

Stauffer was responsible for remedial actions off of the PVC Plant property ("OU 2") whichincluded:

Closed Buried Sludge Pits-Place a drainage layer on top of the existing synthetic cap and cover with a 2nd synthetic cap;cover with topsoil and revegetate

Former PVC Resin Storage Area-Cover the entire area with a double synthetic cap, then cover with topsoil and revegetate

Ground Water-Install a line of ground water recovery wells at the northern and southern edges of thecontaminant plume, collect and reuse the ground water in Formosa's plant operations. Installtwo monitoring wells at the southern edge of the plume and provide alternate water supplyfor existing contaminated wells. Initially several residences were supplied alternative potablewater via tanker truck by Stauffer Chemical. Several properties including three businesses(Stapleford Chevrolet, Diamond State Telephone and Foraker Getty) had their drinking waterwells replaced by Stauffer in 1987 as part of the remedial action.


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Both Stauffer and Formosa were responsible to conduct Operations and Maintenance("O&M") activities to insure the effectiveness of their respective remedial actions. Theseactivities include conducting regular inspections, making repairs to liners and caps as necessary,and routinely monitoring the ground water recovery system to assure that it is capturing thecontaminant plume.

On December 18, 1991, EPA issued an Explanation of Significant Differences ("ESD") forthe Delaware City PVC Plant Site. This ESD described two significant changes to the remedyselected in the ROD. The first one involved the addition of an air stripper to remediate therecovered ground water instead of having the water remediated and reused in Formosa's plant.Although at the time of the FS reuse of the ground water was the preferred alternative, it wasdetermined in the ROD that not all of the recovered ground water could be consumed inFormosa's operations. Since this may have required the installation of an air stripper at somefuture date, it was decided that a dedicated air stripper was the most reliable alternative. Thesecond change to the remedy involved replacing several existing earthen lagoons (viz. the threeoff-grade batch lagoons and the storm water reservoir pond) with one above-ground storage tank.The tank was designed with a capacity of about 2.3 million gallons to replace these facilities.

Remedy Implementation

On April 28, 1987, EPA, Formosa and Stauffer agreed to amend the May 14, 1984Administrative Order on Consent for the purposes of carrying out the remedial actions specifiedin the ROD dated September 30, 1986. Both Formosa and Stauffer then began work on remedialdesigns to address their respective portions of the remedy.

Formosa began the remedial design and initiated its remedial action ("RA") under OU 1(sludge removal) shortly after the ROD was issued. The OU 1 RA included excavation of thePVC sludge and contaminated soils from the three earthen off-grade batch pits, two aerationbasins, and RV #1 (a former stormwater reservoir); lining of the concrete aeration basins and twoearthen ditches; and backfilling of the three off-grade batch pits. Additionally, Formosaconstructed an above-ground tank to contain stormwater runoff instead of rebuilding RV #1 andthe off-grade batch pits and constructing an additional stormwater reservoir. Formosa alsoconstructed RV #2, a new impoundment used to store stormwater from the northern section ofthe plant. The water from the tank and RV #2 are pumped to the aeration lagoons for treatmentprior to discharge to the Delaware River.

Stauffer completed its remedial design and initiated remedial action ("RA") under OU 2 onSeptember 29,1989. The ROD called for a recovery system, initially a line of six ground waterrecovery wells at the northern edge of the plume and another six wells at the southern edge, plustwo monitoring wells at the southern edge of the plume, to collect the contaminants and to


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prevent the plume from migrating further. The ground water recovery system is operational andthe effluent from the air stripper is discharged to the Delaware River.1

Formosa completed its R£ activities under OU 1 on June 30, 1992 and Stauffer likewisecompleted its RA activities under OU 2 on April 6, 1992. Remedial Action Reports were signedto document both completions.

Additional Contaminants Investigations -1992-2002

At the time that Stauffer was nearing completion of the construction activities originallyenvisioned under OU 2 another contaminated ground water plume was discovered east of thePVC plant. In 1992 the Star Enterprises Refinery, east of and adjacent to the plant, discovered aground water plume on their property contaminated with chlorinated organic compounds. Atapproximately the same time, PVC resins were also found in vicinity of the Akzo NobelChemical and the VPI Mirrex facilities north and east of the Formosa plant where they were notexpected. In 1993 Stauffer, now AstraZeneca Pharmaceuticals, LP ("Zeneca") began a Pre-Design Investigation, designated as "Phase n," to determine to what extent the PVC Site was thesource of the contaminant plume beneath Star. Formosa also began in 1993 an investigation ofsoil contamination associated with the newly discovered buried PVC resins.

During the Phase n Ground Water study, EPA suspected that EDC contamination hadpenetrated the Columbia aquifer and reached the Potomac aquifer beneath. Furtherinvestigations were initiated in 1996. Stauffer's investigation found no EDC in the Potomacaquifer but did find a very localized area of ground water contamination flowing east of the Sitein the Columbia aquifer.2

After Stauffer discovered the eastern plume in 1996, further investigation was done in 1999to verify the finding. In 2000, a Pre-Design investigation was conducted, which consisted of:monitoring well installation, water level measurements, ground water sampling, installation oftest borings, pumping well installations, pumping well specific capacity tests, and ground watercapture zone modeling. These tasks provided the data needed to design a pump and treat system

1 A dedicated air stripper was installed to remediate contaminated ground water instead of having Formosarecover and reuse the ground water in their plant cooling system (where it would have been remediated via air-stripping in the plant's cooling towers). Stauffer volunteered to install the air stripper because Formosa was reluctantto use contaminated ground water in its cooling system. Additionally, Formosa may not have been able to utilize allof the contaminated ground water for cooling, which would have necessitated directing some of it to Formosa'swaste water treatment plant ("WWTP"). Formosa was concerned that its WWTP may not have been able to handlethe types and levels of contamination present in the ground water. The decision to install the dedicated air stripperwas documented by EPA in an Explanation of Significant Differences dated September 18, 1991.

2 At one point, EPA separately designated the newly-discovered contaminant plume in the eastern portionof the Site as Operable Unit 3 ("OU 3") and the additional soil contamination associated with the buried PVC resinsas Operable Unit 4 ("OU 4"). As both investigations progressed, it was decided that these separate actions could behandled more efficiently under the two pre-existing operable units. By the time both studies were completed in2002, the additional ground water contamination in the eastern portion of the Site had been made part of OU 2 andthe soil contamination associated with the buried PVC resins had been made part of OU 1.

Delaware City PVC Plant SiteSecond Five-Year ReviewSeptemb.2004 10 A R 3 0 0 7 5 8

to address the eastern plume. Stauffer submitted the pump and treat system design to EPA onMay 1, 2001, and construction of the pump and treat system started on July 9, 2001.

The pump and treat system consists of five pumping wells with their associated valves,pumps, piping, related electrical equipment (i.e., digital flow meter, power and telemetry wiring),and a pipeline for conveying the extracted ground water to the existing air stripper for treatment.On September 26,2001, a Preliminary Close Out Report was signed which signified constructioncompletion of the pump and treat system and construction completion for the Delaware CityPVC Plant Site. These recovery wells are continuing to withdraw a significant amount ofcontamination from area ground water and are mitigating the continued migration ofcontaminants eastward. The capture zone of the pump and treat system is managed so as to no,extend beyond the eastern property line. Significant withdrawals of contaminants from thesource area will also reduce contaminants in the downgradient direction.

Formosa's soil investigation associated with buried PVC resins was completed in 2002 anofound no additional contaminated soil.

Systems Operations/Operation & Maintenance

Operation and Maintenance ("O&M"), as stated in the ROD, includes conducting regularinspections and, as necessary, repairs to the liners and caps, and annual monitoring of the grou-idwater recovery system to insure that it is capturing the plume. Annual ground water monitoringat the Site started in 1993 and is ongoing. The pump and treat system is now part of the groundwater recovery system constructed in 1992 and the eastern plume will be monitored insubsequent annual ground water monitoring until the cleanup goals stated in the ROD areachieved. Zeneca and its contractor, Roux Associates, conduct O&M for the off-plant propertyportion of the remedy, including the landfills and ground water remediation and Formosaconducts the O&M activities on plant property (aeration basins, ditches, and tank).

Formosa continues to complete repairs on the liner of one of the aeration lagoons (nowdesignated by Formosa as the "eastern aeration basin") on Plant property. Formosa staff andcontractors continue to search for the source of a small leak of approximately nine gallons perday (~9 gallons per day) in the primary liner of the eastern aeration lagoon, which is beingcontained by the secondary liner. Formosa reports on its O&M activities to EPA monthly.

Zeneca performs weekly maintenance inspections of the pump and treat system and makesrepairs as needed. Zeneca reports on its activities quarterly to EPA and DNREC.

V. Progress Since the Last Five-Year Review

Since the last five-year review dated March 23, 1999, the source area investigationconcerning additional contamination found on the eastern portion of the Site was completed(1999) along with the installation of additional ground water recovery wells to address this plume(2001). Annual monitoring and evaluation of the ground water remedial action has continued. A


A R 3 0 0 7 5 9

Preliminary Close-Out Report was signed on September 26, 2001 documenting constructioncompletion at the Site.

Ground water monitoring results during 2003 led to EPA and Zeneca agreeing on theabandonment of 15 ground wlter wells in the western portion of the Site. Information detailed inthe 2003 Ground Water Interceptor System Monitoring Performance Results report showed thatthe ground water plume in the western area of the Site (western plume) was shrinkingdemonstrably along the north/south axis of ground water flow west of the ground water divide. Inaddition, contamination levels in the eastern portion of the Site, some two orders of magnitudehigher than levels in the western plume, are likewise being contained and reduced. EPA willcontinue to monitor these trends following this five-year review.

VI. Five-Year Review Process

Administrative Components

The five-year review included the following administrative components:

-Community Involvement-Interviews -'-Document Review-Data Compilation and Review ;

-Site Inspections-Five-Year Review Report Development and Review

Community Involvement

Activities to involve the community in the five-year review were initiated by publishing an adin the Delaware News Journal on November 25, 2003 informing residents in the local area thatEPA was conducting a five-year review at the Delaware City PVC Plant Superfund Site. Inaddition, a meeting was conducted with two New Castle County officials on January 7, 2004.EPA's Community Involvement Coordinator for the Site (Mr. William Hudson) and the EPARemedial Project Manager (RPM) for the Site (Frederick Mac Millan) also conducted severalinterviews with local residents who live near to the Site.

During the interviews, representatives of EPA summarized the requirements of the five-yearreview inspection for the Delaware City PVC Plant Site and asked for any input or concerns onthe protectiveness of the remedy.

Following issuance of this Five-Year Review document, a notice will be sent to a localnewspaper announcing that the Five-Year Review report for the Delaware City PVC PlantSuperfund Site is complete, and that the results of the review and the report are available to thepublic in the information repository located at the Delaware City Public Library at 250 5th Street,Delaware City, DE 19706.

Delaware City PVC Plant SiteSecond Five-Year ReviewSeptember 2004 12 A R 3 0 0 7 6 0

Interviews

On January 7, 2004, EPA conducted two separate meetings with Delaware City officials, theGeneral Manager for the Land Use Department and a planner with the Office of EmergencyPreparedness. These two offitials had somewhat differing views about the Site.

The General Manager for the Land Use Department was not fully aware of the status of theDelaware City PVC Plant as a Superfund Site. He did not feel very well informed about the Sueactivities, nor was he aware of any incidents at the Site requiring a local government response.EPA's November 2003 public notice regarding the five-year review was the first time the Sitehad come to the General Manager's attention that he could recall. He did feel that Siteoperations had raised the community's concerns about area drinking water, since ground water isa major source of drinking water for Delaware.

The planner for the Office of Emergency Preparedness was somewhat more cognizant of thepresence of the Site, along with other Superfund sites, as a possible emergency planning concern.He knew that the local fire department had responded to the Site during past building demolitionoperations. The planner also understood that people in the surrounding community were veryaware of the large number of hazardous waste sites in that area of Delaware (New CastleCounty). He also believed that citizens were obtaining information about the PVC Site locally,but did not specify those sources. The official was interested in receiving a final copy of EPA'sfive-year review and possibly arranging a meeting with EPA and other area officials onemergency response planning regarding the Site.

EPA updated both officials about progress at the Site, especially regarding the on-goingground water remediation.

EPA interviewed three local citizens about the Delaware City PVC Plant Site on January 28,2004. Area citizens were likewise not very aware of the Site's existence, nor did they feel theyhad been kept informed about activities concerning the Site. One resident reported that his wellwas sampled annually (for the performance monitoring of the Site's ground water interceptorsystem), yet had not been told anything about the results for his well. There were also someconcerns about odors coming from the vicinity of the Site. One resident was also concerned andbelieved that area cancer rates were high.

EPA shared information with these residents about the Site, one of the oldest in Region 3dating back to 1982. EPA informed these residents that health risks from Site contaminants werelow and that the remedies intended to control these contaminants, primarily in ground water,were functioning properly3. EPA also assured them that this five year review report and otherinformation about the Site would be made available to the public and that any future informationregarding sampling of their wells would be forwarded to them once completed.

3 EPA did not know about a ground water well contamination issue in the western portion of the Site at thetime of these interviews. See Section VII, Technical Assessment, Question C for details.

Delaware City PVC Plant SiteSecond Five-Year ReviewSeptember 2004 13

A R 3 0 0 7 6 I

Document Review

This five-year review consisted of a review of relevant documents including the ROD, ESD,administrative orders on consent, O&M records, monitoring data and applicable or relevant andappropriate requirements (AKARs). See Attachment 3 for a list of these documents.

Data Compilation and Review

Air Stripper

On December 18,2003, EPA Region 3 completed a risk assessment associated with theperformance of the air stripper to determine whether the air stripper currently operating at theDelaware City PVC Plant Site yields air emissions of acceptable concentrations in terms ofhuman health risk for all three volatile contaminants of concern, trichloroethylene (TCE), 1,2-dichloroethane (EDC), and vinyl chloride monomer (VCM). Overall, based on the availableinformation, the air stripper emissions do not pose an unacceptable risk.

EPA estimated the maximum annual average ambient air concentration at the closest possibleresidential exposure setting to the air stripper, approximately 286 meters away. The parametersconsidered in this analysis were the physical characteristics of the air stripper itself (stack height,air flow, etc.) and the emission rate for a given compound from the air stripper (contaminantconcentration in ground water being treated, concentration of the contaminant influent to thestripper, influent flowrate, stripping efficiency, etc.). Because the O&M data provides thechemical concentrations as the total of all three contaminants, it was not possible to determinethe exact proportions of the contaminants. Therefore, bounding-type risk estimates wereperformed, where the contamination was conservatively assumed to be either 100% TCE, or100% EDC, or 100% VCM.

Based on the concentrations of contaminants in the ground water and the continuingperformance of the air stripper, the estimated concentration of TCE, EDC and/or VCM in air atthe closest possible residential exposure setting to the air stripper was 0.28184 ug/m3. At thisconcentration, none of these contaminants pose an unacceptable human health risk. Residents inother locations beyond this distance would be expected to have even lower risks.

Ground Water Monitoring

Information detailed in the 2003 Ground Water Interceptor System Monitoring PerformanceResults report showed that the ground water plume in the western area of the Site (westernplume) was shrinking demonstrably along the north/south axis of ground water flow west of theground water divide (see Attachment 3). In addition, contamination levels in the eastern portionof the Site, some two orders of magnitude higher than level in the western plume, are likewisebeing contained and reduced. Sampling for the 2004 Ground Water Interceptor SystemMonitoring Performance Results report was completed in May 2004 and EPA expects to receivethis report in August 2004. EPA will continue to monitor these trends following this five-yearreview.


A R 3 0 0 7 6 2

Site Inspections

On March 19, 2003, a site visit was conducted by EPA accompanied by representatives fromDNREC, Formosa and Zeneca. The Formosa property and relevant portions of the VPI Mirrexproperty, the ground water tefemetry station, and the air stripper were inspected. The DelawareCity PVC Site review team consisted of Mr. Steve Johnson, Environmental Engineer, DNREC.Mr. Qazi Salahuddin, DNREC Project Manager, Ms. Kim Bennett, Environmental AffairsManager, Formosa Plastics Corporation of Delaware, Mr. Robert Shay, Environmental ProgramManager, AstraZeneca Pharmaceuticals LP, and Mr. Paul Ekoniak, also employed by Zeneca.Weather was overcast and windy, with temperatures in the low 40s.

In general, Site conditions appeared to be good. The VPI Mirrex and Formosa propertieshousing the aeration basins and reservoirs were enclosed by fencing that appeared to be in gooclcondition. The air stripper on Zeneca's or Akzo's property was likewise secured and wellmaintained. The remote telemetry building on Zeneca's property is locked and is visitedregularly. There is active security at the Formosa property.

The eastern aeration basin on Formosa property had been taken out of service to locate andrepair a leak in October of 2002. It had been drained and was awaiting evaluation and repair inthe Spring. During that time, process water was redirected to the western aeration basin througha Crossover pipe and storm water is stored in the onsite tank and is metered to the westernaeration basin for treatment. The western aeration basin is in good repair and has adequatecapacity to handle the extra load resulting from the eastern aeration basin being taken out ofservice.

Extensive repairs to the eastern aeration basin liners were needed. Formosa removed theaerator (aerating mixer) and finished cleaning out the basin in preparation for repairs in August2003, and solicited bids for major repair work. The repairs included replacing the topgeomembrane layer, adding an additional geotextile layer beneath the top geomembrane and thenewly replaced wear pad geomembrane which had been damaged by the feet of the aerator andreplacing the clogged leak detection geonet layer. Also needed were repairs to torn membranesections, especially side portions of the membranes about 1.5 feet up the sides of the basin fromthe bottom. Following the completion of these repairs in November 2003, the eastern aerationbasin was refilled but additional leaks were discovered in the repaired sections of the liners. Twoof three leaks were found and repaired, but the third leak (~9 gallons per day) has yet to beisolated. Current plans call for a specialist company to be engaged by Formosa to find and repairthe remaining leak in the newly refurbished eastern aeration basin, but those efforts are beinghampered by cold weather at this time. Since temperatures above 40 degrees F in excess of oneweek are required prior to leak detection, these latest repairs began in March 2004 and arecontinuing. EPA remains in regular contact with Formosa regarding this continuing O&M issue.

An additional Site visit focusing primarily on ground water issues was conducted by EPA onOctober 1, 2003. The review team for that site visit included Mr. Hermineo Concepcion,Hydrogeologist, EPA Region 3, Mr. Qazi Salahuddin, DNREC Project Manager, Ms. KimBennett, Environmental Affairs Manager, Formosa Plastics Corporation of Delaware, Mr. Robert


Shay, Environmental Program Manager, AstraZeneca Pharmaceuticals LP, and Dr. Nathan Epler.Hydrogeologist, Roux Associates, Inc., representing AstraZeneca. Ground water wells areinspected annually and most were in good condition at the time of the inspection. Locating somewells was difficult since the well locations had become overgrown. Two wells were found to bedamaged and were slated for replacement by Zeneca.

VII. Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

Yes. The ground water extraction and treatment system continues to operate effectively andis expected to achieve the cleanup standards specified in the ROD in approximately 20 years.

The ROD addressed contamination in the Columbia or uppermost aquifer. As mentionedpreviously, a 1997 ground water study found no contamination in the next lower aquifer, thePotomac. As described below, contamination was recently found in a well in the Potomacaquifer. It is unknown at this time whether or not the contamination is site-related.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial actionobjectives (RAOs) used at the time of the remedy selection still valid?

Yes.

Since the last five-year review in 1999, there have been no changes in the physical conditionsof the Site that would affect the protectiveness of the remedy.

Remedial Action Objectives (RAOs)

The Remedial Action Objectives (RAOs) were to prevent exposure to VOC-contaminatedsludges and soils associated with PVC production, to prevent soil-to-ground water contaminationfrom VOC-contaminated sludges and soils, and to prevent exposure to ground water contaminatedwith VOCs via drinking the water. These RAOs remain valid.

Changes in Standards and To Be Considereds

Applicable or Relevant and Appropriate Requirements (ARARs) were not identified in theROD for this Site since the ROD was issued prior to SARA. However, as part of the first Five-Year Review, a list of potential ARARs was developed to help evaluate the protectiveness of theremedy. There have been no changes in these potential ARARs and to be considereds at the Site.All potential ARARs associated with the discharge of treated effluent from the air stripper and theaeration basins are being met by the remedy. The ground water cleanup standards for the Sitehave yet to be met. A list of ARARs is included in Attachment 5.


A R 3 0 0 7 6 4

Changes In Exposure Pathways. Toxicitv and Other Contaminant Characteristics

Toxicity factors for TCE have changed since the 1986 ROD and the 1991 ESD. To determinewhether the ROD ground water cleanup standards for VCM (1 ug/L), EDC (0.94 ug/L), and TCE(2.7 ug/L) are still protective, the concentrations of these chemicals underwent an updated riskassessment using current exposure and toxicity characteristics.

These same ground water cleanup goals were retained for the ESD in 1991 and reevaluatedduring a risk assessment for the first Five-Year Review in 1998. The cancer risk associated withthe 1986 ROD target ground water concentrations was approximately 3x 10s and the non-cancerrisk "Hazard Index" ("HI") was less than 1; both within EPA's acceptable risk range for cleanupgoals (cancer risk between IxlO"4 and IxlO'6 and a non-cancer risk HI of less than 1) for adult andchild residents.

The updated risk assessment for exposure to ground water conducted for this Five-YearReview continued to find that the ground water performance standards in the ROD for the Sitecontaminants EDC, TCE and VCM are protective.

Potential risks posed by the air stripper emissions were also reevaluated. Because thechemical concentrations were reported as a total TCE, EDC and vinyl chloride (monomer, VCMor VC), it was not possible to determine the exact proportions of the contaminants. Therefore, amore conservative approach was used. Bounding-type risk estimates were performed, where thecontamination was assumed to be, variously, 100% TCE, 100% EDC, or 100% VC.

The following toxicity factors were used:

TCE-former

TCE-new lo

TCE-new hi

EDC

VC

ReferenceConcentrationmg/m3

—0.04

0.04

0.005

0.1

InhalationReference Dosemg/kg/day

—

0.01

0.01

0.0014

0.028

Inhalation UnitRiskm3/ug

0.0000017

0.0000057

0.0001 1

0.000026

0.0000043

InhalationCancer SlopeFactor1 /mg/kg/day

0.006

0.02

0.4

0.091

0.015

Multiple risk factors are shown for TCE, because the TCE risk factor is currently under reviewby EPA. The "former" value is from 1987, and is still being recommended by at least one EPAregion because of concerns over the "new" value from 2001. The "new" cancer slope factor("CSF") is given as a range, so "new-lo" represents the low end of the new CSF, and "new-hi"represents the high end of the new CSF. Default residential exposure assumptions were used.


Using this approach and under the worst case, the cancer risks would not be expected toexceed 2E-5, and may be orders of magnitude lower. The worst case situation would be if all ofthe contamination were TCE, and if the highest proposed cancer slope factor for TCE were used.Even under this scenario, the cancer risk is within the EPA's acceptable range.

• -I

This same conservative approach was used to determine the non-cancer Hazard Index for theair stripper emissions. Under the worst case, the Hazard Index would not be expected to exceed0.2, and may be much lower. The worst case scenario for non-cancer risks would be if all thecontamination were EDC, and if a child resided at the location of the highest annual averageambient concentration (estimated at 286 meters from the air stripper). Even under this scenario,the Hazard Index does not exceed 1, and therefore no adverse effects would be expected.

No changes to the exposure pathways used in the ROD are warranted. No other changes inexposure pathways (except a potential indoor air pathway which is discussed below), toxicity orother contaminant characteristics have been observed since the last five-year review in 1999. Nochange to the ground water cleanup standards is warranted. Current estimates call forachievement of ground water cleanup standards in approximately 20 years.

Question C: Has any other information come to light that could call into question theprotectiveness of the remedy?

Yes.

Over the past several years, EPA has gained a greater understanding that ground watercontamination by volatile organic compounds (VOCs) may give rise to the possibility of vaporintrusion into structures above a VOC-contaminated ground water plume. This is influenced bythe variety of factors, including the concentration and characteristics of VOCs in ground water,the depth of the contaminated plume, the characteristics of the structures above the plume(basements, etc.), seasonal and other circumstances. Exposures may also vary based upon setting(i.e., residential v. industrial) and by the type(s) of activities going on under these scenarios.

In this particular setting, the issue is complicated by the ongoing industrial operation (i.e.polyvinyl chloride production) that may be an additional airborne source of contaminants likethose in the ground water. EPA plans to further evaluate this issue and discuss this issue with theFormosa and Zeneca and the owners/occupants of buildings that may be located above thecontaminated ground water plume where vapor intrusion may pose a potential risk within sixty(60) days of the date of this Five-Year Review.

On February 19, 2004, the Delaware Department of Health and Social Services, Office ofDrinking Water ("DE ODW") took a routine sample of a drinking water well in the vicinity of theDelaware City PVC Site and found EDC at a level of 24.1 ug/L. This level exceeds the federalSafe Drinking Water Act ("SDWA") maximum contaminant level ("MCL") of 5 ug/L. This resultwas confirmed later that month, showing a level of 31 ppb, likewise above the MCL.


September 2004 & R 3 0 0 7 6 6

In March 2004 DE ODW issued a drinking water violation to the Getty gasolinestation/convenience store at the intersection of Route 13 and Route 72 in Bear, Delaware ("GettyStation") where the samples were taken in February, and notified DNREC, who in turn notifiedEPA. Separate sets of samples were taken by DNREC, DE ODW and Zeneca.

j

EDC is one of the contaminants of concern at the Delaware City PVC Plant Site. The GettyStation is located near the southern end of the western contaminated ground water plume at thvSite. The original Getty Station drinking water well and four other wells in this area werereplaced by Stauffer in 1987 as part of the remedial action for OU 2 due to contaminationassociated with the Site. The new wells were constructed to obtain water from a greater deptLbeyond the Site contamination. This most recent contamination was found in this newer, dec:;: rwell at the Getty Station.

EPA, DNREC, DE ODW and Zeneca (formerly Stauffer) are investigating the contaminal tnin the Getty Station well to determine the source of contamination (site-related or not), and thmost appropriate course of action. DE ODW has placed the Getty Station well in violation o:drinking water regulations and has issued orders that the well not be used as a supply of drink; ngwater. DNREC, DE ODW and Zeneca sampled the Getty Station well and all the other drinkingwater wells replaced by Stauffer in 1987 for EDC and other site-related contaminants under EPAoversight on May 12, 2004. During that sampling event, the levels of EDC found at the Gett,Station well were generally about 50% lower than the levels discovered in February 2004 thoughstill significantly above the MCL, ranging from 11 ug/L to a high of 15 ug/L. No EDC was foundin any of the other wells replaced by Stauffer in 19874. DNREC also arranged for a series ofinspections of the Getty Station to uncover other possible sources of EDC that could havecontaminated area ground water and the drinking water well. So far no other sources have beenidentified. The investigation is continuing to confirm the source and nature of this exceedamx Atthis time, no other potential source except the contaminated ground water plume beneath thewestern portion of the Site has been identified.

A revised sampling plan for this area of the Site (western plume) is being developed by Zenrcaat the direction of EPA to better characterize the plume in this area. DNREC and DE ODW willcontinue to participate in this effort. In the meantime, Zeneca has begun and will continue toprovide a alternate potable water source in the near term, (a bottled water dispenser) for employeeconsumption and for the coffee business associated with the Getty Station. Zeneca is alsoplanning to "tie-in" the Getty Station to the municipal water supply should that become necessary.If EPA determines that the EDC is from the Site, additional remedial measures will be evaluated.

There is no other information that calls into question the protectiveness of the remedy.

4 One of the three laboratories reported a qualified (J) detection at a level well below the method detectionlimit and far below the MCL. That result is considered questionable.


September 2004 19 - A R 3 0 0 7 6 7

Technical Assessment Summary

According to the data reviewed and the site inspection, the remedy is functioning as intendedby the 1986 ROD and the 1991 ESD. The air stripper continues to function acceptably withinSuperfund risk parameters and the pump and treat system continues to address the plume ofcontaminated ground water on the east and especially the west side of the ground water dividerunning north/south beneath the Site.,. EPA is currently investigating the source and nature ofground water contamination recently found in the Getty gas station well and also plans to evaluatethe potential for vapor intrusion into structures above the VOC-contaminated ground water plume.There is no other information that calls into question the protectiveness of the remedy.

VIII. Issues

Table 2 - Issues

- ' , " . - ' ' . ' . ' ..'issuer"":- : > i v ' r

" "' rffj.'-^ - ,

Potential Site-related Contaminant of Concern indrinking water well in vicinity of the Site

Possible vapor intrusion into structures abovecontaminated ground water plume

Currently AffectsProtectiveness

(Y/NF)

N

N

Affects FutureProtectiveness

(Y/N) " *

Y

Y

IX. Recommendations and Follow Up Actions

Table 3

Issue<• "

- v» . - -*;-,.srv^r*

Potentially Site-related Contaminantof Concern indrinking water wellin vicinity of the Site

Recommendations/FoUow-Up Actions

^J :tift^.

* ' "'.-i V;<<S*-U V '

Revisedsampling planfor ongoingground waterinvestigation todetermine ifSite-related

PartyResponsible

Zeneca

OversightAgency

EPA/DNREC/DEODW

MilestoneDate

10/30/04

AffectsProtectiveness?

(Y/N)

Current

N

Future

Y


A R 3 0 0 7 6 8

Issue

Possible vaporintrusion intostructures abovecontaminated groundwater plume

Recommendations/Follow-Up Actions

tf

1) Discussissuesw/Formosa,Zeneca & otherowners/occupants2) Developaction plan ifnecessary

PartyResponsible

ZenecaFormosaEPA

OversightAgency

EPA/DNREC

MilestoneDate

11/30/04

AffectsProtectiveness?

(Y/N)

Current

N

Future

Y

X.< Statement on Protectiveness

The remedy for OU 1 is fully protective. The remedy has effectively reduced and/or elimiru.tedthe sources of site-related contaminants to ground water. These actions included the excavationand removal of sludges from various surface impoundments, capping of closed areas, theinstallation of liners and leachate detection in basins used in process operations.

The remedy for OU 2 is currently protective in the short-term but may not be protective in ' r,elong-term. The remedy currently protects human health and the environment by effectivelyreducing the migration of Site-related contaminants in ground water, by capturing and removingthem from ground water, and by eliminating them through treatment. These measures havereduced the risk of exposure to Site contaminants and will continue until ground water cleanupstandards are achieved. Current estimates call for completion of the ground water remedy at theSite to take another 20 years. EPA will continue to monitor these trends following this five-ye^ •review.

The OU 2 remedy may not be protective in the long-term depending on the outcome of theinvestigation to determine the source and the nature of the contamination in the Getty gas stationwell. The drinking water well, installed there in 1987 as part of the remedial action under OU 2as specified in the 1986 ROD, was found to be contaminated with EDC, one of the contaminantsof concern at the Site. This and other area wells were sampled under EPA oversight on May 12,2004. In the meantime, an alternate potable water source has been provided and plans are beingmade to tie-in the gasoline station to the municipal water supply if necessary. If the EDC is site-related, additional remedial measures will be evaluated.

Vapor intrusion into structures above the VOC-contaminated ground water plume may alsocall into question the protectiveness of the OU 2 remedy. EPA plans to further evaluate this issueand discuss this issue with Formosa, Zeneca and other owners/occupants of buildings that may be


A R 3 0 0 7 6 9

located above the contaminated ground water plume where vapor intrusion may pose a potentialrisk.

Overall the Site is protective of human health and the environment in the short-term but maynot be in the long-term because of the issues discussed above for OU 2.

XL Next Five-Year Review

The next five-year review will be completed no later than September 2009, five years from thesignature date of this review.

Attachments

Attachments 1, 2, 3 and 4 follow this page.


September 2004 A R 3 0 0 7 7 Q

DELAWAREPVC SITE

m^m

FORMOSA PLASTICSCORPORATION

DRAGON CREEK

-•••&,-v.v-^r

:?i*^;:^-i_^%^̂ ,;f >^

EXPLANATION

OURCE: USGS SAINT GEORGES ANDDELAWARE CITY, DELAWAREQUADRANGLES, 7.5 MINUTE SERIESTOPOGRAPHIC

ATTACHMENT 1

SITE LOCATION

DEUM/AJRE CITY PVC SITEPERFORMANCE MONTTORWG

STAUFFER MANAGEMENT CCXv^ANY U.C

ROUXROUX ASSOCIATES I

EntHronmenlli Consi/Tir*

CompttO! tr>- NE

by N£

INC PfoieO

FJe NO ICH14705 V

ATTACHMENT 2 c\J

Maps Depicting Locations of Contaminant Plume1990-2004

1990 Conditions 1996 Conditions

CDCDCOor•ct

" ATTACHMENT 2 (Con't)

Maps Depicting Locations of Contaminant Plume1990-2004

2001 Conditions

CO

CDCDCO

2004 Conditions

ATTACHMENTS

List of Documents Reviewed

-Superfund Record of Decision: Delaware City PVC. DE. dated September 30, 1986

-Explanation of Significant Differences. Delaware City PVC Superfttnd Site. New Castle County.DE. dated September 18, 1991

-Superfund Remedial Action Report. Operable Unit 1. Delaware City PVC Site. Delaware City.DE. dated June 30.1992.

-Five-Year Review Report. Delaware City PVC Superfund Site. Delaware City. DE. datedMarch 23, 1999

-Potential Applicable or Relevant and Appropriate Requirements (ARARs) table, from Five-YearReview Report, Delaware City PVC Superfund Site, Delaware City, DE, dated March 23, 1999

-Interim Remedial Action Report, Operable Unit 2, Delaware City PVC Superfund Site, DelawareCity, New Castle County, Delaware dated June 14,2002

-Annual Ground Water Interceptor System Performance Monitoring Results for 2003, 2002, 2001by Roux Associates, AstraZeneca remediation contractor

-Delaware City PVC: Estimated Risks from Air Stripper Emissions: Memorandum from JenniferHubbard, Toxicologist, Technical Support Section, EPA Region 3 to Frederick Mac Millan,Remedial Project Manager, EPA Region 3, dated December 18, 2003

-Risk Assessment Issues for 2003 Five-Year Review. Delaware City PVC: Jennifer Hubbard,Toxicologist, Technical Support Section, EPA Region 3 to Frederick Mac Millan, RemedialProject Manager, EPA Region 3, dated June 15, 2004

-Formosa Plastics Corporation monthly reports

-Quarterly reports submitted by A.C. Shultes, Inc., AstraZeneca's O&M contractor

Delaware City PVC Plant SiteSecond Five-Year ReviewSeptember 2004 26 A R 3 0 0 7 7 ^

ATTACHMENT 4

List of Potential ARARs and To Be Considereds (TBCs)

As part of the Five-Year Review Report for the Delaware City PVC Superfund Site,Delaware City, DE, dated March 23, 1999, EPA evaluated the following potential ARARsand TBCs:

-Safe Drinking Water Standard, Maximum Contamination Level Goals (MCLGs)-Safe Drinking Water Standard, Maximum Contaminant Levels (MCLs)-Delaware Surface Water Quality Criteria Standards as amended, February 26, 1993-Delaware Regulations Governing the Control of Air Pollution-Delaware River Control Board (DRCB) Standards

Environmental standards identified or promulgated after the ROD is signed becomeARARs only if they bring into question the protectiveness of the remedy. Based on thisevaluation, EPA believes that the clean-up standards identified in the ROD remain protective

Delaware City PVC Plant SiteSecond Five-Year Review A D *sSeptember 2004 * ' ft I X O

Potential ARARs and To Be Considereds from First Five-Year Review (March 23, 1999)

ARAR or TBC

I. CHEMICAL SPECIFIC

Safe Drinking WaterStandard, MaximumContaminant Level Goals(MCLGs)

Safe Drinking WaterStandard,Maximum ContaminantLevels (MCLs)

Delaware Surface WaterQuality Criteria Standards asamended, February 26, 1993

Legal Citation

40CFR§ 141.50-51

40CFR§ 141.61-62

Delaware Surface WaterQuality Standards asamended, February 26,1993 Sections 3, 4, 5, 6, 8,9, 10, 11.1, 11.2, 11.3,11.4, 11. 6, and 12

ARARClass

RelevantandAppropriate

RelevantandAppropriate

Applicable

Requirement Synopsis

Non-enforceable health goals for public watersupplies. The NCP requires that non-zero MCLGsshall be attained by remedial actions for groundwater that is a current or potential source ofdrinking water, where the MCLGs are relevant andappropriate under the circumstances of the release.

Enforceable standards for public drinking watersupply systems (with at least fifteen serviceconnections or used by at least 25 persons). TheNCP requires that MCLs, for those contaminantswhose MCLG is zero, shall be attained by remedialactions for ground water that is a current orruMential source of dnnkirsg water, where theMCLs are relevant and appropriate under thecircumstances of the release. MCLs for VCM,EDC and TCE are 2.0 ppb, 5 ppb, and 5 ppb,respectively

Criteria are provided to maintain surface water forstreams, lakes, rivers, and standing water inwetlands of satisfactory quality consistent withpublic health and recreational purposes, thepropagation and protection of fish and aquatic life,and other beneficial uses of water, water effluent

Applicability toSelected Remedy

The Site-specific clean-upcriteria are at or below non-zero MCLGs.

The Site-specific clean-upcriteria are at or belowMCLs. ROD cleanup levelfor VCM, EDC, and TCE are.1.0, 0.94, and 2 . 7 ppb,respectively

Any surface water dischargemust not cause exceedancesof these criteria, if morestringent than federal waterquality criteria, in theDelaware River.

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ARAR or TBC

II. LOCATION SPECIFIC

Ground Water ProtectionStrategy of 1984 EPA 440/6-84-002

III. ACTION SPECIFIC

A. Air

Control of Air Emissionsfrom Air Strippers atSuperfund Ground WaterSites, June 15, 1989 EPAOSWER Directive 9355.0-28

Delaware RegulationsGoverning the Control of AirPollution

Clean Air Act

Legal Citation

No Legal Citation

No Legal Citation

DNREC Air PollutionControl RegulationsNumber 2, 19, and 24

Listed as hazardous airpollutants

ARARClass

To BeConsidered

To beConsidered

Applicable

Requirement Synopsis

. . . . . . .

Identifies ground water quality to be achievedduring remedial actions based on aquifercharacteristics and use.

Policy to guide the selection of controls for airstrippers at ground water sites according to the airquality status of the site's location (i.e., ozoneattainment or nonattainment area)

Sets forth the requirement that a permit isnecessary to operate an air stripper if emissionswill exceed 2.5 Ibs/day. Section 2 describesgeneral conditions. Section 19 deals with odor.Section 24 deals with volatile organic compounds.

Emission less than 10 tpy for individual HAP andless than 25 tpy for combination HAPs.

Applicability toSelected Remedy

i

The classification of theaquifers at this Site as ClassII i

i

To be considered indetermining if air emissionscontrols are necessary for anair stripper because KentCounty is an ozone non-attainment area. Sourcesmost in need of controls arethose with emissions rates inexcess of 3 Ibs./hr or 15Ibs/day or a potential rate of10 tons/yr of total VOC's.

If emissions exceed 2.5ibs/day then the substantiverequirements of theregulations must be met.Permit are not ARARs

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IVI;iw:irr Cnv PVP l'l:im ^li,-

Second Five-Year KcvicwSeptember 2004 2 9

ARAR or TBC Legal Citation ARARClass

Requirement Synopsis Applicability toSelected Remedy

B. Water

Clean Water Act (CWA);National Pollutant DischargeElimination SystemRequirements

40CFR§ 122.41(e),122.44, 122.45, 125.61-63, 125.73

Applicable Enforceable standards for all discharges to watersof the United States.

Discharge limits shall be metfor all on-site dischargesfrom the ground watertreatment facility. Onlysubstantive requirementsshall be met since thetreatment facility is on Site.

Delaware River ControlBoard (DRCB) Standards

DRCB Ground WaterProtected Area Regulation4; Water Code of theBasin, Section 2.20.4

The operation of a water withdrawal project shallnot cause long-term progressive lowering ofground water levels, permanent loss of storagecapacity or substantial impact on low flows ofperennial streams.

Delaware RegulationsGoverning Control of WaterPollution, amended 6/23/83

Delaware RegulationsGoverning Control ofWater Pollution, amended6/23/83 Sections7,8,9,10,11,12, and 13

Applicable Contain water quality regulations for dischargesinto surface and ground water.

Applicable for discharge oftreated ground water intosurface water.

Delaware RCRA Delaware RCRA264.il 7,264.228

Landfilling of waste. [30 year post closure care(including prevent migration of liquids throughlandfill, promoting drainage and minimize erosionof cover, accommodate settling, restrict postclosure use of property as necessary, landfillclosure and post-closure.

Delaware RCRA 264.221,264.227,264.228 operation of plant wastewater treatment system[prevent overtopping, monitoring for leaks, etc.

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Delasvare City PVC Plum SiteSecond I- ' ive-Ycar ReviewSeptember 2 < M ) 4

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