fourth five-year review report · delaware city pvc plant

111111111111111111111111111111111111111111111

SDMS DoclD 2184664

FOURTH FIVE-YEAR REVIEW REPORT

· Delaware City PVC Plant Site

New Castle County, Delaware

Prepared by:

U.S. Environmental Protection A~ency

Region III

Philadelphia, Pennsylvania

crfz_[ ~01 .tf Date '

Table of Contents

List of Acronyms ........................................................................................................................ iv

Executive'-Summary ........................................................................ : .................... : ...................... \Ti

Five-Year Review Summary Form ............................................................................................. ix

I. Introduction .................................................... : ...................................... : .................................. 1

II. Site Chronology ........................ : .............................................................................................. 2

Table 1: Chronology of Site Events .................................................................................2

III. Background.............................................................................................................................6

Physical Characteristics ....................................................................................................6 ' '

Land and Resource Use ....................................................................................................7

History of Contamination .................................................................................................7

Initial Response Activities ······································~·························································8

Basis for Taking Action .............................-:. ............................................. .-.......................8

IV. Remedial Actions ...................................................................................................................9

Remedy Selection .............................................................................................................9

Remedy Implementation ................................................................................................. 11

Systems Operations/Operation & Maintenance .............................................................. 12

V. Progress Since the Last Five-Year Review ........................................................................... 13

VI. Five-Year Review Process ........................ ' ........................................................................... 14

Administrative Components ........................................................................................... 14

Community Involvement ................................................................................................ 14

Interviews .......................................................... : ............................................................ 15

Document Review .......................................................................................................... 15

Data Compilation and Review ................................................................. : ...................... 16

Site Inspection ................................................................................................................ 17

VII. Technical Assessment ......................................................................................................... 18

Question A: Is the remedy functioning as intended by the decision documents? .......... 19

Question B: Aie the exposure assumptions, toxicity data, cleanup levels, and remedial

action objectives (RAOs) used at the time of the remedy selection still valid? ............. 19

Question C: Has any other information come to light that could call into question the protectiveness of the remedy? ........................................................................................23

Technical Assessment Summary ....................................................................................23

VIII. Issues..................................................................................................................................25

Table 2 - Issues ...............................................................................................................25

IX. Recommendations and Follow Up Actions ..... : ................................................................... 25 (

Table 3 - Recommendations/Follow-Up Actions ........................... ~..............................25

X. Statement on Protectiveness ................................................................................................26

XI. Next Five-Year Review ......................................................................................................27

EPA Evaluations of Buildings above Contaminated Groundwater Plume at Potential Risk for Vapor Intrusion

Maps Depicting Locations of Contaminant Plume

ATTACHMENT 4 ...................................................................................... ~·······························59

List of Documents Reviewed

APPENDIX A .............................................................................................................................28

ATTACHMENT 1 - Site Location ............................................................................................31

_ATTACHMENT 2 - Generalized Map Showing Areas of Soil Remediation ...........................32

ATTACHMENT 3 ................................~ .....................................................................................33

ATTACHMENT 5 ...................................................................................................................... 61 - '

List of Potential ARARs and To Be Considereds (TBCs)

Ill

List of Acronyms

AOC

ARAR

CERCLA

CFR

CO Cs

DEODW

DNREC

EDC

EPA

FYR

GCS

GMID

GMUC

GMZ

GPRA

HEUC

MCL

NCP

NPDES

NPL

O&M

OU

Administrative Order on Consent

Applicable or Relevant and Appropriate Requirement

Comprehensive Environmental Response, Compensation and Liability Act

Code of Federal Regulations

Contaminants of Concern

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

Five-Year Review

Groundwater Collection System

Insufficient Data to determine contaminated Groundwater Migration Control Status ,

Groundwater Mitigation Under Control

Groundwater Management Zone

Government Performance Review Act

Human Exposure Under Control

Maximum Contaminant Level

National Contingency Plan

National Pollutant Discharge Elimination System

National Priorities List

Operation and Maintenance

OperaOle Unit

IV

VI

ppm

PVC

RA

RAO

RI/FS

ROD

RPM

RV

SARA

SDWA

SWRAU

TCE

ug/L

vc

voe

WWTP

Parts per million

Polyvinyl ~hloride r

Remedial Action

Remedial Action Objective

Remedial Investigation/Feasibility Study

Record of Decision

Remedial Project Manager

Reservoir

Superfund Amendments and Reauthorization Act

Safe Drinking Water Act

Site-Wide Ready for Anticipated Use

'frichloroethylene

Micrograms per Liter (equivalent to parts per billion)

Vinyl Chloride Monomer (Vinyl Chloride; VC)

Vapor Intrusion

Volatile Organic Compound

Waste Water Treatment Plant

v

Executive Summary

The Delaware City PVC Plant Site (PVC Site or Site) is located approximately two miles northwest of Delaware City, New Castle County, Delaware. The Site originated from a polyvinyl chloride (PVC) manufacturing facility that contaminated area soils and groundwater with PVC sludge and volatile organic compounds (VOCs). Historically, the Site consisted of two operable units, OUl, which consists of source material in the soil, and OU2, which consists of groundwater contamination. Site-related groundwater cleanup, to date, has focused primarily on groundwater contamination in the Columbia aquifer west of Schoolhouse Road. Recent investigations of groundwater contamination east of Schoolhouse Road beneath the Delaware City Refinery has documented Site-related groundwater contamination in the Columbia and Potomac aquifers. The area of Site-related groundwater east of Schoolhouse Road appears bounded by Dragon Run Creek and underlays only refinery property.

In May 1984, EPA and the Delaware Department of Natural Resources and Environmental Control (DNREC) entered into a Consent Order with Stauffer Chemical Company and Formosa Plastics Corporation of Delaware to perform a Feasibility Study (FS) aµd to implement an approved Remedial Action (RA). EPA issued a Record of Decision (ROD) for OUl and OU2 in 1986. The remedy described in the ROD included:

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

• lining of the three off-grade batch pits, two aeration basins, storm water retention pond, and two unlined ditches;

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

• collection and treatment contaminated groundwater to prevent further plume migration; and

• operation and maintenance of the caps and groundwater recovery system.

In 1991, EPA issued an Explanation of Significant Differences (ESD). The changes in the ESD included:

• addition of an air stripper to remediate recovered groundwater instead of having water remediated and reused in the existing Formosa plant; and

• replacing several earthen lagoons with an above-ground storage tank.

OUl and OU2 (west of Schoolhouse Road) of the Site achieved construction completion when the Preliminary Closeout Report was signed on September 26, 2001. The trigger for this 5YR was the date of the third 5YR, September 10, 2009.

The assessment of this fourth 5YR Report found the remedy was constructed in accordance with the ROD and ESD.

VI

EPA finds that overall the remedy for Site soils OUl is fully protective. The remedy for OU2, groundwater contamination, is protective in the short-term. Long term protectiveness for groundwater .is deferred. The current groundwater remedy addresses contamination west of Schoolhouse Road and is believed to be protective of human health and the environment. However, Site-related groundwater east o~ Schoolhouse Road has not beeµ fully evaluated. Final determination of the protectiveness of groundwater will be made following the evaluation of Site-related groundwater contamination underneath the Delaware City Refinery.

There are two historic plumes associated with the Site. The western plume was first identified early on and led to the Site being listed on the NPL. A second plume on the eastern side of the facility property was identified during the remedial design. The pumping system for the eastern plume area was designed to capture contamination on the Formosa property west of Schoolhouse Road. Both the western and eastern plumes west of Schoolhouse Road are currently being addressed by the groundwater pump and treat system. The pumping well network for both the eastern and western plumes share a common treatment system. Remedial actions at the plant have continued to reduce the source of groundwater contamination. The groundwater extraction and treatment system continues to operate as designed. The remedial action is expected to achieve the cleanup standards specified in the ROD.

Investigations conducted at the Delaware City Refinery under oversight by the EPA and DNREC RCRA programs identified Site-related contaminants east of Schoolhouse Road within the Columbia and Potomac aquifer. This contamination appears to have migrated from the-PVC Plant pr9perty eastward underneath the refinery~ This plume eventually turns south where the leading edge appears to be bounded by Dragon Run Creek. No Site-refated contaminants have been identified south of Dragon Run Creek in this area. EPA raised concerns about this contamination to Site responsible parties in a November 20, 2013 letter from the Acting Director, Hazardous Site Cleanup Division. A meeting with the responsible parties was held on May 9, 2014 to request the responsible parties investigate and incorporate this part of the plume into the remedial action. The responsible parties have not responded to EPA at this time.

Institutional controls restricting the use of groundwater in the area of Site-related contamination are not part of the ROD. However, a DNREC Memorandum of Agreement between the Division of Air and Waste Management and the Division of Water Resources , created a Groundwater Management Zone (GMZ) for the Delaware City Industrial Area in April 2008 (see Attachment 1). The GMZ generally includes the area between State Highway 1 on the, west and the Delaware River on the east, and Red Lion Creek to the north and Dragon Run Creek to the south. The GMZ includes the area of known and suspected Site-related groundwater contamination. The GMZ prohibits any new public or domestic water supply wells in the unconfined Columbia aquifer and any underlying aquifer unit hydraulically connected to the Columbia aquifer. ,

During this 5YR period, the western plume has decreased in area. Currently, one monitoring well (OW-10) has contaminant concentrations at or just above the clean-up goals. Contaminant concentrations in the eastern plume continue to decline.

Vapor intrusion (VI) into structures above the VOC-contaminated groundwater plume west of Schoolhouse Road had called into question the protectiveness of the remedy, during the third 5YR period. In April 2014, EPA evaluated the potential for vapor intrusion with the owners/occupants of buildings that appear to be located above the eastern groundwater plume, excluding the newly documented contamination under the Delaware City Refinery. This effort

VII

included: the development of individual plume maps for the site contaminants of concern (COCs), development of groundwater screening levels for potential VI, and the evaluation of building overlaying groundwater contamination greater than the screening levels. These findings are detailed in Appendix A of this 5YR Review. EPA evaluated these properties and found little or no potential risk associated with vapor intrusion. EPA conducted a similar evaluation of VI during this 5YR period. These findings concur with the findings of the third 5YR.

Government Performance Review Act (GPRA) Measure Review As part of this 5YR the GPRA Measures have also been reviewed. The GPRA Measures and their status are provided as follows:

Environmental Indicators Human Health: Current Human Exposure Controlled (HEUC) Groundwater Migration: Insufficient Data to determine contaminated Groundwater Migration Control Status (GMID)

Site-Wide RAU Site-Wide Ready for Anticipated Use (SWRAU) is currently projected for September 30, 2018; however, the completion of the groundwater evaluation east of Schoolhouse Road needs to be completed in order to make a final SWRAU determination.

VIII

v Five-Year Review Summary Form

SITE IDENTIFICATION

Site Name: Delaware City PVC

EPA ID: DED980551667

NPL Status: Final

Multiple OUs? Has the site achieved construction completion? Yes Yes

REVIEW STATUS

Lead agency: EPA -If "Other Federal Agency" was selected ~bove, enter Agency name:

Author name (Federal or State Project Manager): Bruce Rundell

Author affiliation: US EPA Region 3

Review period:, January 6, 2014 - August 15, 2014

Date of site inspection: April 8 & 14, 2014

Type of review: Polley ' /

Review number: 4

Triggering action date: September 10, 2009

Due date (five years a'fter triggering action date): September 10, 2014

IX

Issues/Recommendations

OU(s) without Issues/Recommendations Identified in the Five-Year Review:

OU 1 Soils: No issues or recommendations

Issues and Recommendations Identified in the Five-Year Review:

OU(s): OU 2 Issue Category: Monitoring Groundwater Issue: Site-related groundwater contamination east of Schoolhouse

Road has not been evaluated and incorporated into Site remedy

Recommendation: 1) Fully evaluate areal extent of contamination and potential impacts to receptors 2) Develop remedial alternatives for this contamination.

Affect Current Affect Future Implementing Oversight Milestone Protectiveness Protectiveness Party Party Date

No Yes PRP EPA September 10, 2019

OU(s): OU 2 Issue Category: Monitoring Groundwater Issue: Potential vapor intrusion into structures above contaminated

groundwater plume.

Recommendation: PRP will collect add1t1onal data and information to assist this evaluation '

Affect Current Affect Future Implementing Oversight Milestone Protectiveness Protectiveness Party Party Date

No Yes PRP EPA Septemb_er 10, 2015

x

Operable Unit: Protectiveness Determination. Addendum Due Date OU1 Protective (1f applicable)·

Protectiveness Statement· The remedy for OU 1 is fully protective The remedy has effectively reduced and/or eliminated the sources of' Site-related contaminants to groundwater. These actions included the _excavation and removal of sludge from various surface impoundments, capping of closed areas, the installation of liners and leachate detection in basins used in process operations.

J[DSl]

Operable Unit: Protectiveness Determmation: Addendum Due Date OU2 Protectiveness Deferred (1f applicable):

September 10, 2019

Protectiveness Statement: The remedy for OU 2 groundwater 1s protective in the short term Final determination of the long-term protectiveness will be made following the evaluation of Site-related groundwater contamination underneath the Delaware City Refinery The remedy currently protects human health and the environment by effectively capturing and removing Site-related contaminants from groundwater on the facility property, stopping the migration of Site-related contaminants in groundwater east of Schoolhouse Road These measures have reduced the risk of exposure to Site contaminants and will continue until groundwater cleanup standards are achieved Site-related contamination east of Schoolhouse Road downgrad1ent of ,the capture zone of the pump and treat system have not been completely evaluated Site-related contaminants in the groundwater comingle with contaminants resulting from refinery operations No human receptors appear to be currently exposed to Site-related contaminants beneath the refinery Contamination appears to discharge to Dragon Run Creek and does not migrate further south No environmental evaluation of Site-related contamination impacts to Dragon Run Creek have been done. EPA will continue to monitor contaminant trends and develop a plan to address Site related contamination east of Schoolhouse Road Vapor intrusion into structures above the VOC-contaminated groundwater plume had called into question the protectiveness of the OU 2 remedy In May and June 2009, EPA evaluated the potential for vapor intrusion with the owners/occupants of buildings that are located above the contaminated groundwater plume, primarily on the eastern portion of the Site, and found httle or no potential risk associated with vapor intrusion This area was re-evaluated in April 2014. No changes in the buildings or operations have been 1dent1f1ed to change these conclusions of protectiveness However, no sampling has been done to confirm these findings The collection of and additional data and 1nformat1on· 1s recommended to confirm these findings Additional details can be found in Section VII Technical Assessment, Question B, and in Appendix A.

XI

[[DS2]

Sitewide Protectiveness Statement (if applicable)

Protectiveness Determination: Addendum Due Date (if Short-term Protective applicable):

September 10, 2019

Protectiveness Statement. Overall the Site 1s protective of human health and the environment in the short-term. Long-term protectiveness will be made following the evaluation of Site-related groundwater contamination east of Schoolhouse Road and the completion of the vapor intrusion evaluation.

XII

Delaware City PVC Plant Superfund Site New Castle County, Delaware

Fourth Five-Year Review Report

I. Introduction /

The purpose of 5YR is to determine whether the remedy at a site is protective ofhuman health and the environment. The methods, findings, and conclusions of reviews are documented in 5YR reports. In addition, FYR reports identify issues found during the review, if any, and recommendations to address them.

The Agency is preparing this Five-Year Review report pursuant to CERCLA § 121 and the National Contingency Plan (NCP). CERCLA §121 states:

Ifthe President selects a remedial action that results in any hazardous substances, pollutants, or contaminants remaining at the site, the President shall review' such remedial action no less often than each five years after the initiation ofsuch remedial action to assure that human health and the environment are being protected by the remedial action being implemented In addition, ifupon such review it is the judgment ofthe President that action is appropriate at such site in accordance with section [104] or [106], the President shall take or require such action. The President shall report to the Congress a list offacilities for which such review is required, the results ofall such reviews, and any actions taken as a result ofs~ch reviews

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

Ifa remedial action is selected that results in hazardous substance's, pollutants, or contaminants remaining at the site above levels that allow for unlimited use and unrestricted exposure, the lead agency shall review such action no less often than every five years after the initiation ofthe selected remedial action.

The statutory requirement to conduct a five-year review applies to CERCLA §121 remedial actions selected after the effective date of the Superfund Amendments and Reauthorization Act (SARA) (October 17, 1986). In accordance with EPA's "Comprehensive Five-Year Review Guidance" (OSWER No. 9355.7-0313) (June 2001), for sites where a statutory review is not specifically required, reviews may be conducted as a matter of policy for any of the following type actions:

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

Delaware City PVC Plant Site

Fourth Five-Year Review

September 2014

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

3. A removal action for a site on the NPL that leaves hazardous substances, pollutants, or contaminants above levels that allow for unlifi1:ited use or unrestricted exposure, and where no remedial action has or will take place.

EPA selected the remedial actions for the Site prior to the effective date of SARA and, therefore, conducts this five-year review as a matter of policy, due to the fact that hazardous substances, pollutants, or contaminants remain at the Site a1;>0ve levels that allow for unlimited use and unrestricted exposure.

This is the fourth 5YR for the Delaware City PVC Site. The triggering action for this policy review is the third 5YR completed on September 10, 2009. This fourth review was conducted for the Site by the Remedial Project Manager (RPM) from January 6, 2014 through August 10, 2014. 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 -- Event

1966 Stauffer Chemical Company (Stauffer) begins manufacture of polyvinyl chloride (PVC) resin from vinyl chloride monomer (VC) at the Site.

Late 1960s Off-grade PVC resins, sludge from wastewater treatment system and residues and 1970s from plant processes are disposed in buried sludge pits, which are closed and

covered.

May 1981 Stauffer sells the PVC plant to Formosa Plastics Corporation of Delaware (Formosa) but keeps the area outside of the PVC plant. Formosa continues operations of the PVC plant to present.

October 23, PVC Plant placed on Interim National Priorities List. 1981



September 2014 2

Date Event

December 20, 1983

Delaware City PVC Plant Site is placed on the final National Priorities List (NPL).

May 23, Stauffer and Formosa agree under an Administrative Order on Consent (AOC) 1984 to complete remedial investigatio~ and perform remediation under EPA

oversight.

September EPA issues Record of Decision (ROD). Formosa and Stauffer divide the 30, 1986 work. Formosa is responsible for the soil remedial actions on the PVC plant

pr()perty (OU 1 ). Stauffer is responsible for soil remedial actions off of the PVC Plant property and all groundwater remediation (OU 2). RA onsite

' construction (PVC sludge removal) at OU 1 begins.

April 28, , AOC amended, Remedial Design Starts for OU 1 and OU 2. 1987 -

March 31, Remedial Design completed, Remedial Action b~gins - OU 1. 1988

September Remedial Design completed, Remedial Action starts - OU 2. 29, 1989 ,/

September EPA issues Explanation of Significant Differences (ESD) for OU 1 and OU 2 18, 1991 for installation of above ground storage tank to-replace 3 ponds (OU 1) and air

stripper to treat groundwater instead of using the existing Waste Water Treatment Plant (OU 2).

' ''

April 6, Interim Remedial Action Report, OU 2. 1992

April 30, Work plan completed for revised RI/FS to address additional groundwater 1992 contamination migrating offsite from eastern portion of the Site and additional

soil contamination from buried PVC resins. Evaluation does not include Delaware City Refinery property east of Schoolhouse Road.

June 30, Remedial Action Report, OU 1. 1QQ? ,

June 30, Investigation of additional groundwater contamination migrating from eastern 1995 portion of the Site begins.

December Investigation to address additional soil contamination from buried PVC resins 12, 1995 begins.

March 23, First 5YR completed at the Site. 1999

Delawar!l City PVC Plant Site


September 2014 3

Date Event

October 25, Additional extraction wells installed under OU 2 in the western plume area. 2000

February 29, Investigation completed on plant property of additional groundwater 2000 ' contamination migrating from eastern portion of the Site.

March 8, Remedial Design for eastern groundwater contamination begins, activities 2001 combined into OU 2.

' July 26, OU 2 construction to address the eastern plume starts. 2001 \

September QU 2 construction for eastern plume completed. 25,2001

)

June 14, Investigation of additional soil contamination from buried PVC resins 2002 completed; any future related activities to be part of OU 1.

June i4, OU 2 Interim Remedial Action report completed. 2002 . August 30, 2002 PRP Groundwater Interceptor System Performance Monitoring Report 2002 - submitted to EPA.

' August22, 2003 PRP Groundwater Interceptor System Performance Monitoring Report 2003 submitted to EPA. (

February 19, Delaware Department of Health and Social Services, Office of Drinking Water 2004 (DE ODW) finds 1 ~2 DCA in drinking water well of 9etty Gas station at 24

ug/L (MCL=5 ug/L), confirmed later that month at 31 ug/L. Getty Gas station contamination located near western plume area.

,

March 11, DE ODW and DNREC notify EPA of 1,2 DCA issue; EPA notifies PRPs. 2004 Later that month, Getty Gas Station directed by DE ODW to cease use of 1,2

' DCA-contaminated well for drinking water; Stauffer provides bottled water.

-May 12, DE ODW, DNREC, EPA and PRP begin year of quarterly sampling regimen 2004 at Getty Station and thfee other affected properties to discern any trends in

contamination after 50% 1,2 DCA drop in Getty well observed.

October 30, Revised sampling plan to include residential wells in the vicinity of the Getty -2004 well.

~



September 2014 4

Date

June 14, 2005

September 21,2005

August 23, 2006

September 19,2006

December 12,2006

November 1, 2007

April 03, 2008

April 10, 2008

September 24,2008

May 27, 2009

June 3, 2009

June 10, 2009

June 11, 2009

August 19, 2009

August 9, 2009

September 10,2009

Event

Reports of last quarterly sampling made available to affected property owners; no trends identified. Except for Getty well, 1,2 DCA exceeds MCL minimally and only sporadically.

2005 Stauffer Groundwater Interceptor System Performance Monitoring Report submitted to EPA.

2006 Stauffer Groundwater Interceptor System Performance Monitoring Report submitted to EPA. '

Following exploratory discussions with EPA and DNREC, Stauffer offers to connect properties affected by 2004 1,2 DCA levels above MCL to public water.

EPA accepts Stauffer's offer to conhect property o_wners to public water under DNREC and DE ODW oversight.

\

2007 Stauffer Groundwater Interceptor System Performance Monitoring Report submitted to EPA. \ -

-DE ODW reports to DNREC and EPA that Getty Gas Station originally affected by 2004 1,2 DCA exceedance is now below MCL of 5ug/L.

DNREC institutes GMZ prohibiting potable groundwater in Delaware City Industrial Area

2008 Stauffer Groundwater Interceptor System Performance Monitoring Report submitted to EPA.

EPA inspects and ·evaluates IENOS Films (currently Bilcare Research) for vapor intrusion issues.

EPA 'inspects and evaluates Formosa Plastics for vapor intrusion issues.

EPA and DNREC conduct FYR Site Inspection w/representatives of Stauffer and Formosa.

EPA conducts community interviews in conjunction with 2009 FYR.

DNREC confirms Getty Gas Station and remaining properties originally affected by 2004 1,2 DCA exceedance connected to public water supply.

-2009 Stauffer Ground~ater Interceptor System Performance Monitoring Report submitted to EPA. '

Third 5YR completed at the Site.



September 2014 5

Date Event

October 8, Groundwater analyzed for the presence of 1,4-dioxane. No 1,4-dioxane 2010 present.

' January 10, 2010 Stauffer Groundwater Interceptor System Performance Monitoring 2011 Report submitted to EPA.

October 11, 2011 Stauffer Groundwater Interceptor System Performance Monitoring 2011 Report submitted to EPA.

August 8, 2012 Stauffer Groundwater Interceptor System Performance Monitoring 2012 Report submitted to EPA.

September 2013 Stauffer Groundwater Inte~ceptor System Performance Monitoring 19, 2013 Report submitted to EPA.

November EPA sends letter from Kathy Hodgkiss, Acting Director, Hazardous Site 20, 2013 Cleanup Division to Stauffer and Formosa concerning likely Site related

contamination from the eastern plume area migrating beneath the Delaware City Refinery, impacting both the Columbia and Potomac aquifers.

April 8, EPA and DNREC conduct FYR Site Inspection w/representatives of Stauffer 2014 and Formosa, and conducts VI evaluation of Formosa

April 14, EPA conducts VI evaluation ofBilcare Research (formerly IENOS Film) 2014

~

May 9, 2014 EPA, DNREC, and DOJ hold meeting with Stauffer and Formosa to discuss Site related contamination under Delaware City Refinery.

May 14, EPA conducts community interviews in conjunction with 2014 FYR. 2014

·Ill. Background

Phy~1cal Characteristics

The Delaware City PVC Plant Site (Site) is located approximately two miles northwest of Delaware City, Delaware (DE) at latitude 39°35'16" N,orth and longitude 75°39'50" West in New Castle County, DE. It is situated east of State Route 13 and just west of Bilcare Research Inc. (formerly IENOS J;ilms Co., VPI Mirrex Corporation; American Mirrex Co.) and the Delaware City Refinery Co. (formerly owned by Valero, Motiva Enterprises, and prior to that Star Enterprise Oil), between Red Lion Creek to the north, and Dragon Run Creek to the south (see Attachment 1 ).

The Site consists of a polyvinyl chloride (PVC) production facility owned and operated by formosa Plastics Corporation (Formosa) and adjacent land owned by others under which contaminated groundwater flows. The land to the east of the Site is primarily industrial; the land to the west of the site is farmland with some housing developments. Housing developments are also located south of Dragon Run Creek. Land to the north of the Site has some industry and rail lines, but is largely undeveloped. Most of the land surrounding the Site is owned by the

(



September 2014 6

Delaware City Refinery. Originally the PVC plant contained a number of unlined earthen lagoons, ditches and sludge pits where off-grade PVC production resins and process wastes were collected. Wastewater and PVC solias were treated in concrete-lined, aerated lagoons that were found to be cracked and potential sources of contamination. The storm water reservoir pond was an unlined, earthen basin that also received process wastewater and PVC solids from the production area (see Attachment 2).

Land and Resource Use

The Site terrain is generally flat. The Plant area itself sits atop a groundwater divide that causes groundwater and groundwater contaminants to flow towards both the west and east. The western-most portion of the contaminant plume moves primarily n~rth and south likely under the influence of a- buried stream channel. The eastern plume migrates toward the east underneath the Delaware City Refinery.

There are some businesses but little residential development in the immediate Site area. Residential developments are present west of Route 13 and south of Dragon Run Creek. Several residences are located downgradient (south) of the western portion of the contaminated groundwater plume. These properties are connected to public water supply.

History of Contamination 1

Stauffer Chemical Company built a carbon disulfide (CS2) production plant around 1960, followed by a PVC production plant in 1966. Several impoundments were constructed as part of the PVC plant. Two of the impoundments were concrete-lined aeration basins, three were earthen lagoons (off-grade batch pits) used to dump off-grade PVC. One was used to collect stormwater and any chemical or oil spills from the PVC plant. This same pond occasionally collected process wastewater.

The Site had two earthen ditches which carried water and a water/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 the aeration basins. In 1978 this burial area was capped with a PVC membrane and earthen cap. PVC resin was stored in a mound west of the CS2 plant and north of the PVC plant. By 1972, storage was discontinued in this area, however, PVC resin remained in the soil. Resin from this pile spread to a wetlands area to the north of the resin storage m;ea. The resin also extended to an area of stressed vegetation northeast of the wetlands that also contained waste sulfur from the CS2 planf. North of the wetlands and the stressed vegetation area is a burial area for the CS2 plant that had previously been capped wit~ a plastic liner and soil From 1966 until May 1981, Stauffer operated the PVC resin production plant and the CS2 production plant at the Site.

Stauffer manufactured polyvinyl chloride (PVC) resin from vinyl chloride monomer (VCM), more commonly known as vinyl chloride (VC), at the Site. In May 1981, Stauffer conveyed to Formosa the PVC production plant but retained ownership of the CS2 plant and kept the area outside of the PVC plant. Formosa has continued to operate the PVC plant to the



September 2014 7

present day. The CS2 is currently owned and operated by Akzo Nobel Chemicals Inc. In April 1982, one of the domestic supply wells on Stauffer's property was found to be contaminated with 1,2-dichloroethane (a.k.a. ethylene dichloride, EDC or 1,2 DCA), VC, and trichloroethylene (TCE). This prompted Formosa and Stauffer to perform a ,hydrogeologic investigation which identified a plume of 1,2 DCA, VC, and TCE in the lower portion of the Columbia aquifer. This contamination was located underneath and west of the PVC plant. Further investigation determined tliat the sources of the groundwater contamination from the PVC plant area were the two unlined ditches, three off-grade batch pits, two aeration basins, and a stormwater reservoir (RV) pond. The sources outside of the PVC plant area were the closed buried sludge pits and a former PVC storage area. Groundwater sampling conducted in March 1982 and April 1983 confirmed that high concentrations of Site-related contaminants had impacted nearby residential wells. Concentrations of VC ranging from 19 parts per billion (ppb) to 220 ppb and 1,2 DCA ranging from 490 ppb to 2,900 ppb were found in private well waters. See Attachment 3 for various depictions of the groundwater plume.

Initial Response Act1v1t1es

The Site was included on the Interim Priorities List in October 1981, proposed for inclusion 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, monitoring wells located in the vicinity of the off-grade batch pits and the PVC burial area documented the presence ofVC, 1,2 DCA, and TCE in the groundwater (Sampling Inspection Report, Ecology & Environment, Inc.). Monitoring Well 8 had 1,2 DCA " at 13,000 ppb and TCE at 15 ppb and Monitoring Well 9 had VC at 370 ppb. Sampling in April 1982 showed that the contaminants had impacted a residential well southwest of the Site with VC at 605 ppb, 1,2 DCA at 4,'500 ppb, and TCE at 12 ppb. Subsequent samples obtained in March 1983 showed that the contaminants had migrated in the groundwater and impacted two additional private wells. Concentrations ofVC ranging from 19 ppb to 220 ppb and 1,2 DCA ranging from 490 ppb to 2,900 ppb were found in these private well water supplies.

In 1984 EPA, DNREC, Stauffer and Formosa signed an Admi~istrative Order on Consent (Docket No. III-84-6-DC) under which Stauffer and Formosa would perform a feasibility study (FS) and carry out remedial actions at the Site as determined by EPA. Stauffer submitted an FS to EPA which was approved on July 15, 1986. This study outlined alternatives for remediating this Site.

Basis for Taking Action

Contaminants

Hazardous substances that have been released at the SiJe in each media include:



September 2014 8

Groundwater Soils 1,2-Dichloroethane (1,2 DCA) 1,2-Dichloroethane (1,2.DCA) Trichloroethylene (TCE) Trichloroethylene (TCE) Vinyl Chloride Monomer (VC) Vinyl Chloride Monomer (VC)

Potential human exposure pathways for Site contaminants evaluated in the risk assessment included a number of scenarios. Direct dermal contact and inhalation of onsite PVC sludge, and the ingestion of groundwater contaminated with 1,2 DCA, VC and TCE constituted the greatest potential human health threat. Direct dermal contact with soils, especially PVC sludge contaminated with 1,2 DCA, VC and TCE were considered the most significant pathway, but also the least likely due to worker protective controls and robust plant ,controls. Inhalation of volatilized contaminants from unlined ditches, pits, ponds and lagoons was determined to be an insignificant pathway at the time of the ROD.

A hydraulic connection between groundwater and Red Lion Creek and Dragon Run, both used for recreation and drinking water, represented a potential surface water exposure pathway.

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

1,2 DCA - 0.94 Micrograms per liter (ug/L)* VC - 1 ug/L TCE - 2.7 ug/L

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

IV. Remedial Actions

The intent of the Remedial Action at the Site was "to abate of sources of contamination and the mitigation of the existing plume of contaminated groundwater. This would involve preventing or reducing: a) infiltration of contaminants through the sources; b) further migration of existing contaminated shallow groundwater; c) direct contact of the soil with PVC resins; d) futu!e contamination of the Potomac Formation, and e) the degradation of surface waters".

Remedy Selection

Under the 1984 AOC, Formosa and Stauffer divided the work at the Site and performed the remedial action activities as operable units (OUs) under EPA oversight. The Delaware City PVC Plant Site was originally divided into operable units as follows:

~ Delaware City PVC Plant Site (


September 2014 9

-OU 1 (Surface actions on PVC Plant Property) -OU 2 (Surface actions off PVC Plant Property, and site-wide groundwater actions)

Formosa was responsible for the remedial actions on the P\;'C plant property (i.e.OUl) which included:

Off-grade Batch Pits, Storm Water Reservoir and Unlined 'nitches-Excavate and remove existing PVC sludge and contaminated soils; install a double synthetic liner, monitoring wells and perform quarterly sample analysis for TCE, 1,2 DCA and VC.

Aerated Lagoons-Excavate and remove PVC sludge, clean and repair lagoons as necessary, install a double synthetic liner and monitoring wells, and perform quarterly sampling analysis for TCE, 1,2 DCAand VC.

Stauffer took responsibility for remedial actions off of the PVC Plant property (OU 2) which included:

Closed Buried Sludge Pits-Placement of a drainage layer on top of the existing synthetic cap and cover with a 2nd synthetic cap; cover with topsoil and re-vegetate.

Former PVC Resin Stprage Area-Cover the entire area with a double synthetic cap, then cover with topsoil and re-vegetate.

Groundwater-Install a line of groundwater recovery wells at the northern and southern edges of the contaminant plume (later referred to as the western plume), collect and reuse the groundwater in Formosa's plant operations. Install two monitoring wells at the southern edge of the we~tern plume and provide alternate water supply for existing contaminated wells. Initially several residences were supplied alternative potable water by Stauffer Chemical via tanker truck. Several properties including three businesses (Stapleford Chevrolet, Diamond State Telephone and Foraker Getty) had their drinking water wells replaced by Stauffer by deeper Potomac aquifer wells in 1987 as part of the remedial action.

Both Stauffer and Formosa, under the 1984 AOC, were required to conduct Operation and Maintenance (O&M) activities to insure the effectiveness of their respective remedial actions. These activities include conducting regular inspections, making repairs to liners and caps as necessary, and routinely monitoring the groundwater recovery system to assure that the contaminant plume does not migrate further.

On December 18, 1991, EPA issued an Explanation of Significant Differences (ESD) for the Delaware City PVC Plant Site. This included modification of the treatment system and closure of the earthen lagoons. Reuse of the groundwater was the preferred alternative at the time of the FS. It was determined, however, that not all of the recovered groundwater could be



September 2014 10

consumed in Formosa's operations and that some water needed to be discharged. A dedicated air stripper was determined to be the most reliable treatment alternative. The ESD added an air ' stripper to treat the recovered groundwater instead of having the water remediated by the Formosa plant. Treated water could then be either reused by the Formosa plant or discharged to the Delaware River. A second change to the remedy involved replacing several existing earthen lagoons (the three off-grade batch lagoons and the storm water reservoir pond) with one aboveground storage tank. The tank was designed with a capacity of about 2.3 million gallons to replace these facilities.

Remedy Implementation

In April 1987, EPA, Formosa and Stauffer agreed to amend the 1984 AOC for the purposes of carrying out the remedial actions specified in the ROD. Both Formosa and Stauffer then began work on remedial designs to address their respective portions of the remedy.

"

Formosa began the remedial design and initiated remedial action (RA) under OU 1 (sludge removal) shortly after the ROD was issued. The OU 1 RA included excavation of the PVC sludge and contaminated soils from the three earthen off-grade batch pits, two aeration basins, and RV #1 (a former stormwater reservoir); lining o~the concrete aeration basins and two earthen ditches; and backfilling of the three off-grade batch pits. Additionally, Formosa constructed an above-ground tank to contain stormwater runoff instead of rebuilding RV #1 and the off-grade batch pits and constructing an additional stormwater reservoir. Formosa also

- constructed RV #2, a new impoundment used to store stormwater from the northern section of the plant. The water from the tank and RV #2 are pumped to the aeration lagoons for treatment prior to discharge to the Delaware Riv~r.

Stauffer completed remedial design and initiated remedial action under OU 2 on Sept~mber 29, 1989. The ROD c·alled for a recovery system, initially a line of six gr,oundwater recovery wells at the northern edge of the plume and another six wells at the southern edge, plus two monitoring wells at the southern edge of the plume, to collect the contaminants and to prevent the plume from migrating further. The groundwater recovery system is operational and the effluent from the air stripper is discharged to the Delaware River.

Formosa completed RA activities under OU 1 on June 30, 1992 and Stauffer likewise completed RA activities under OU 2 on April 6, 1992. Remedial Action Reports were signed to document both completions.

Additional Contaminants Investigations - 1992-2002

In 1992 the Star Enterprises Refinery (currently Delaware City Refinery), east of and adjacent to the plant, discovered a groundwater plume on their property contaminated with chlorinated organic compounds. At approximately the same time, PVC resins were also found in vicinity of the Akzo Nobel Chemical and the VPI Mirrex facilities north and east of the Formosa plant where they were not expected. At that time Stauffer was nearing completion of the construction activities originally envisioned under OU 2. In 1993 Stauffer began a Pre-Design Investigation, designated as "Phase II," to determine to what degree the PVC Site was the source Delaware City PVC Plant Site


September 2014 11

of the contaminant plume beneath Star. Formosa also began an investigation of soil contamination associated with the newly discovered buried PVC resins in 1993.

- During the Phase II Groundwater Study, EPA suspected that 1,2 DCA contamination had penetrated the Columbia aquifer and reached the Potomac aquifer beneath. Further investigations were initiated in 1996. Stauffer's investigation found no 1,2 DCA in the Potomac aquifer but did find a very localized area of groundwater contamination flowing east of the Site in the Columbia aquifer.

After Stauffer discovered the eastern plume in-1996, a further investigation was done in 1999 to verify the findings. In 2000, a Pre-Design investigation was conducted-; which consisted

- I

of monitoring well installation, water level measurements, groundwater sampling, installation of test borings, pumping well installations, pumping well specific capacity tests, and groundwater capture zone modeling. These tasks provided the data needed to design a pump and treat system to address the eastern plume underneath the Formosa Property. Stauffer submitted the pump and treat system design to EPA on May 1, 2001. Construction of the pump and treat system started on July 9, 2001.

The pump and treat system for the eastern plume 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 groundwater to the existing air stripper for treatment. On September 26, 2001, a Preliminary Close Out Report was signed which signified construction completion of the pump and treat system and construction completion for the Delaware City PVC Plant Site. These recovery wells continue to withdraw contaminated groundwater and limit migration of contaminants eastward. The capture zone of the pump and treat system is managed so as to not extend beyond the eastern property l_ine. Significant withdrawals of contaminants from the source area will also reduce contaminants in the downgradient direction by cutting off the contaminant source.

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

Although not part of the Site remedy, a Groundwater Management Zone (GMZ) for the Delaware City Industrial Area was created by DNREC in April 2008. The GMZ generally includes the area between State Highway 1 on the west and the Delaware River on the east, and Red Lion Creek to the north and Dragon Run Creek to the south. The GMZ prohibits any new public or domestic water supply wells in the unconfined Columbia aquifer and any underlying aquifer unite hydraulically connected to the Columbia aquifer.

\

Systems Operat1ons/Operat1on & Maintenance

Operation and Maintenance, as stated in the ROD, includes annual monitoring of the groundwater recovery system to ensure that it is capturing the plume on the facility property, and -- - conducting regular inspections and repairs, as necessary, to the liners and caps. Annual groundwater monitoring at the Site started in 1993 and is ongoing. The pump and treat system constructed in 2001 to address contamination associated with the eastern plume is now part of

I



September 2014 12

the groundwater recovery system constructed in 1992. The eastern plume, west of Schoolhouse Road, has also been examined in subsequent annual groundwater monitoring events. This will continue until the cleanup goals stated in the ROD are achieved. Stauffer contractor, Roux Associates, conducts O&M for the off-plant property portion of the remedy, including the landfills and groundwater remediation and Formosa conducts the O&M activities on plant property (aeration basins, ditches, and tank).

Formosa reports on its O&M activities to EPA monthly. Stauffer performs weekly , maintenance inspections of the pump and treat system and makes repairs as needed. Stauffer

' reports on its activities quarterly to EPA. Information on the condition of Formosa's and Stauffer's respective systems are described under Site Inspections in Section VI below.

V. Progress Since the Last Five-Year Review

Actions Taken Since Last Five-Year Review -

Issues from Recommendations/ Party Milestone Action Date(s) of Previous Follow-Up Actions Responsible Date Taken and Action Review Outcome Potential Site- Complete Stauffer 8/19/09 ' Affected 12/12/06 to related connection of I properties 8/19/09 contamination affected properties connected to in drinking to public water line public water water wells in line vicinity of site Possible 1) Monitor Formosa 9/10/14 Conducted 4/8/14 vapor chemical use, EPA site visit and Formosa, intrusion into 2) Insure heath interviews of 4/14114 structures and safely programs Formosa Bilcare above in place for areas Plastics Research groundwater overlying plume, Corp. and contamination 3) Monitor land Bilcare plume use and facility Research,

operations ' Inc.

Since the third 5YR dated September 10, 2009, concentration levels in both the western and eastern plume have decreased. Currently, only one well in the western plume has contamjnate concentrations above the clean-up level.

EPA will continue to monitor these trends following this fourth 5YR. In addition, EPA and the responsible parties will conduct a vapor intrusion study to confirm the findings of the 3rd

and 4th Five Year Review that there are little or no risks posed by vapor intrusion. See Appendix A for further details.



September 2014 13

VI. Five-Year Review Process

Admin1strat1ve Components

The 5YR 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

A notice informing the public that EPA is performing a 5YR of the Site was placed in the Delaware State News on May 16, 2014. EPA conducted community interviews on May 14, 2014. EPA Remedial Project Manager (RPM) for the Site (Mr. Bruce Rundell) met with the current Directors of Public Safety for, Delaware City, President of Delaware City Fire Co.I, and with local residents who live near to the Site.

During the interviews, EPA representatives summarized the requirements of the 5YR inspection for the Delaware City PVC Plant Site and asked for any input or concerns on the protectiveness of the remedy.



September 2014 14

Interviews

On May 14, 2014 EPA conducted separate meetings with the Director of Public Safety for Delaware City, and the President of Delaware City Fire Co.1. Both officials had similar views about the Site. Each knew of the Site but had experienced no issues that required their involvement or response during their respective tenures. Neither felt very well informed about the Site or knew of any particular community concerns. EPA reviewed the Site history and the progress of the remedial actions. Both officials were pleased with the progress. The President of the Fire Company expressed concerns for the safety of fire crews if a response was necessary. EPA informed him that current risks due to remedial activities would not pose a risk to his crews and that the facility operators would be the best source of information on the plant operations and safety.

EPA also spoke to several local residents and shared information about the Site. EPA informed these residents that health risks from Site contaminants were low and that the remedies intended to control these contaminants, primarily in groundwater, were functioning properly. EPA also reviewed the progress of groundwater remediation with the residence, and informed

\

them that this 5YR report and other information about the Site would be made available to the public once completed.

In general, the public interviewed is very satisfied with the project and thinks EPA has done and continues to do a "good job" with issues regarding the Site itself. The respondents do not feel threatened by the Site work or the management or operation of the Site. As to the issues that received the most attention during these interviews, respondents primarily cited the economy. Sensitivity in the local area to environmental issues ran high and community interest or concern about the Site was also elevated, more so among local citizens. Overall, people felt less than well informed about the Delaware City PVC Plant Site. As to effects on the surrounding community from the Site, respondents most often cited odors from the neighboring Delaware City Refinery, although they were made aware that the Site did not include that facility.

Document Review

This 5YR consisted of a review of relevant documents including the ROD, ESD, administrative order on consent, O&M records, monitoring data and a collection of potentially applicable or relevant and appropriate requirements (ARARs) developed for the Site for the first 5YR. (It should be noted that the ROD for this Site pre-dated the 1986 amendments to the Superfund statue which among other things, established the requirement for remedial actions to comply with ARARs unless a waiver is obtained.) See Attachment 4 for a list of these documents.



September 2014 15

Data Compilat1on and Review

Air Stripper

Air emissions from the stripper were evaluated for this 5YR. During the year, the groundwater pumping rate varies from 60 to 70 gal/min. The air stripper tower is 72 feet in height and has an air flow rate of 4,200 CFM. The closest building is approximately 200 feet away, so no downwash calculations were made for the air stripper tower.

OSWER Directive 9355.0-28, "Control of Air Emissions from Superfund Air Strippers at Superfund Groundwater Sites", states that emissions in most need of control are those that exceed three pounds per hour (lbs/hr) during any one hour, or fifteen pounds per day (lbs/day) during any twenty-four hour period, or a potential rate of 10 tons per year (ions/yr) of total voes.

This air quality analysis for the Delaware City PVC air stripper system satisfies two requirements of the 5-Yr Review:

1) To evaluate whether or not the air stripper system is still complying with the emission limits set forth in the OSWER Directive, and

2) To estimate the maximum annual average ambient air concentrations ofVOCs due to the operation of the air stripper system.

There are three COCs in the groundwater pumped to the ai~ stripper system: 1,2 DCA, VC and TCE. The combined concentration of these VOCs in the groundwater influent is 26.1 ug/L. The maximum rate of groundwater extraction is 70 gal/min. In this analysis, it was assumed that 100% of the voes are §tripped out of the groundwater into the air.

Using the maximum groundwater flow rate of70 gal/min and the maximum recorded total VOC concentration in the influent in the study period (26.1 ug/L), the total amount of VOCs released to the atmosphere are 9.13E-04 lbs/hr, 2.19E-02 lbs/day, and 8.0 lbs/yr. These are below the emission limits of 3 lbs/hr, 15 lbs/day, and 10 tons/yr stipulated in the OSWER Directive, so the air stripper system is in compliance. It should be noted that when the groundwater remedial system began operation approximately 8 lbs/day ofVOCs were being removed.

To facilitate the calculation~of annual ambient air concentrations of VOCs due to the air stripper system, it was assumed that 100% of these three voes were stripped from the groundwater. The VOCs again are 1,2 DCA, VC, and TCE.

The EPA screening air dispersion model SCREEN3 was used to calculate the 1-hr average and the annual average ambient air concentrations downwind of the air stripper. The maximum concentrations were estimated to occur at 390 meters (1279.5 feet) away from the air stripper exhaust point. The results are the following:



September 2014 16

Volatile Groundwater Air Maximum Maximum RSL RSL Compound Concentration Stripper 1-hour Annual Residential Residential

Emission Ambient Ambient Carcinogenic Noncancer Rate@ Air Air Target Risk Hazard 70gpm Average Average (TR)= lE- Index (HI)

06 = 0.1 µg/L g/s µg/m3 µg/m3 µg/m3 µg/m3

1,2 DCA 13 5.74E-05 5.36E-03 4.29E-04 0.094 0.73 vc 2.1 9.27E-06 8.66E-04 6.92E-05 0.16 10

TCE 11 4.86E-05 4.53E-03 3.63E-04 0.43 0.21

The maximum annual ambient air average concentrations of the COCs were compared to the corresponding VOC concentrations from the November 2013 Residential Inhalation Risk Screening Level (RSL) Tables. The values from the RSL tables are calculated at a cancer risk of lE-06 and a non-cancer Health Index ofO.l. All of the annual ambient air concentrations are below the RSLs. For TCE, the maximum 1-hr concentration is also below the not-to-exceed Residential value of 2 µg/m3.

Groundwater Monitoring

Information detailed in the Groundwater Remedial System Performance Monitoring For 2013 (most recent) report showed that the groundwater contamination in the western plume area has continued to shrink. Only one monitoring well, OW-10, has COC detection at or above the cleanup value. 1,2 DCA was detected at 9.2 ug/l, which is above the clean-up level of 0.94 ug/l. VC was detected at the cleanup level of 1 ug/l (see Attachment 3). Currently only Well Dis pumping on the west side of the divide. This is being done to maintain sufficient flow to the air stripper. Contamination levels in the eastern portion of the Site (eastern plume, west of Schoolhouse Road) are still significantly higher than the cleanup levels. Annual evaluations do show signs that the plume concentrations are being reduced. The highest level of 1,2 DCA and VC were found in MW-14 at 4,140 ug/l and 456 ug/l, respectively. Maximum TCE concentrations were found in OW-56 at 355 ug/l. EPA will continue to monitor these trends following this 5YR.

Site Inspection

On April 8, 2014, a Site visit was conducted by EPA accompanied by representatives from DNREC, Formosa and Stauffer. A number of areas on the Formosa property were inspected inclt~ding the pumping and monitoring wells for the eastern contaminated groundwater plume, the treatment building and air stripper, the two former earthen ditches, the two capped sludge pits, the additional storm water reservoir (RV#2), and process building above the groundwater plume. The Delaware City PVC Site review team consisted of: Mr. Bruce Rundell, RPM, EPA; Ms. Morgan Price, Project Manager, DNREC; Ms. Kirn-Bennett, Eilviromhental Affairs Manager, Formosa Plastics Corporation of Delaware; Mr. Dan Piersimoni, Environmental Technician also with Formosa Plastics; Mr. John-Paul Rossi, Project Manager, Stauffer, ~fr. Charles Elmen~orf, Environmental Remediation Senior Director, Stauffer; Mr. Nathan Epler, Ph.D. Principal Delaware City PVC Plant Site


September 2014 17

Hydrogeologist, Roux Associates, Inc. (Roux), consultant to Stauffer, and Mr. Jade Borowski, Project Engineer, also employed by Roux. The weather was sunny and clear with temperatures in the low 60s. Heavy rains had passed through the area the previous night and morning of the Site visit.

There is active security at the Formosa property and all area perimeters are fenced with locked gates at access points. In general, the property appears to be in good condition. The two former earthen ditches were previously lined with synthetic material and cement during the remedial action. They are now used to route storm water and wastewater to the above-ground storage tank and were in use and functioning. The northern ditch appeared to be in good condition. The additional storm water reservoir (RV#2) was in good condition. The two capped sludge pits were in good condition. The cap is checked weekly and the grass mowed as needed.

The five pumping wells for the eastern plume, designate<l~Wells Q, R, P, 0, and Sare located in a north/south line on Formosa property adjacent to the Bilcare Research property line (see Attachment 3, 2002 Conditions Map). All of the wells are installed in concrete chambers that extend about two feet above ground and about six feet below ground. All five wells were inspected. Each had a locked steel access door, a ladder and a confined space warning on the inside surface of the access door. The bunker for all wells were in good condition. Some standing water was still present in some vaults. This was due to the heavy rain earlier in the day that had not had time to drain out the vault floor drains. The well head, pipes and access ports are all located above the floor of the chamber. The pressure gauges were functioning. The pump and treat system is checked weekly. Iron fowling is a problem with the pumping wells. The pumping wells are chlorinated monthly to reduce iron fowling Pumping wells are redeveloped as needed. The treatment building, air-stripper, and all the electronic equipment appears to be maintained and in operating order. The air stripper tower is fed by two pumps in parallel. One of these pumps was down for repair at the time of the visit. This would not affect the operation of the system. The air stripper tower is over 20 years old and oversized for the current contaminant loading. Stauffer is considering modification to the air-stripper system to increase the efficiency of the treatment system.

Groundwater wells are inspected annually although all wells are not sampled during each Annual Performance Monitoring event. Roux Associates has reported no damaged wells to EPA.

VII. Technical Assessment

Note that this Technical Assessment pertains to OUI and that portion of OU2 of the Site west of Schoolhouse Road. This assessment does not address Site-related groundwater contamination east of Schoolhouse Road. Site-related groundwater contamination east of Schoolhouse Road will be investigated and addressed as part of the Sites next 5YR. '



September 2014 18

Question A. Is the remedy functioning as intended by the dec1s1on documents'?

Yes. The groundwater extraction and treatment system continues to operate effectively. Cleanup in the western plume area of the Site is nearly complete.

The ROD addressed contamination in the shallow Columbia aquifer. As mentioned previously, a 1997 groundwater study found no contamination in the deeper Potomac aquifer. In 2004, 1,2 D~A contamination was found in a well in the Potomac aquifer belonging to a Getty Gas Station. The Getty Gas Station well is located on US Route 13 in the vicinity of the western plume area. While it could not be confirmed that the contamination was Site-related, bottled water was provided by Stauffer to prevent exposure to persons using this well. EPA, DNREC and DE ODW sampled several Potomac drinking water wells in the area for the presence of 1,2 DCA. In 2006, EPA and DNREC approved of a proposal by Stauffer to place four properties whose wells had been impacted by 1,2 DCA on public water to prevent any further potential exposure. This work was done by Stauffer under DNREC oversight. The waterline extension was completed in August 2009. Detections of 1,2 DCA above the maximum contaminant level for 1,2 DCA (5 ug/L) decreased in these wells with no detections of 1,2 DCA by 2008.

Question B Are the exposure assumptions, tox1c1ty data, cleanup levels, and remedial

action obwct1ves (RAOs) used at the time of the remedy selection still valid?

Individual questions responsive to this topic are answered below.

Have standards identified in the ROD been revised, and does this call into question the protectiveness of the remedy?

The performance standards identified in the ROD are:

Vinyl chloride (monomer or VC) - 1 ug/L; 1, 2-dichloroethane (12DCA or 1,2 DCA) - 0.94 ug/L; TCE - 2. 7 ug/L.

Using the most current guidance and toxicity values, an updated risk assessment was performed on the current ROD groundwater standards. The following are the risk results:

GW Risk-based Adult HI Child HI Lifetime Cancer Performance Risk Goal (ug/L)

1,2-DCA 0.94 1.4E-02 1.0E-02 1.9E-06 TCE 2.7 2.4E-01 3.7E-01 3.0E-06 vc 1.0 1.0E-02 2.2E-02 l.lE-05

Total Risk 2.7E-01 4.0E-01 l.6E-05

Non-cancer human health index (HI) are below EPAs acceptable criteria of 1. Cancer risk are



September 2014 19

below or within EPA's acceptable criteria of lE-04 to lE-06. These findings indicate that the performance standards are protective.

MCLs were not mentioned in the ROD, since the remedy was selected before the statutory requirement the ARARs. Current federal MCLs are 2 ug/L, 5 ug/L, and 5 ug/L, respectively. Therefore, achievement of the ROD standards would still meet Federal MCLs. The State of Delaware has lowered the MCL for TCE to 1 ug/l. This change does not affect the protectiveness of the remedy, because the standard selected by the ROD are protective ..

Do newly promulgated standards call into question the protectiveness of the remedy?

No.

Have TBCs changed, and could this affect the protectiveness of the remedy?

No. EPA Regional Tap Water Screening Levels) for 1,2-DCA, TCE and VC are 0.015 ug/L,

0.26 ug/L and 0.015 ug/L. While these are lower than the ROD standards, the RSLs are screening, not cleanup, levels. The ROD standards were confirmed to be protective (see Attachment 5).

Has land use or expected land use on or near the Site changed?

On-site land use is still industrial. There are residential developments about one mile or more west and south of the Site. It appears that there may be some agricultural land use in the area also. Significant changes from previous years have not been reported.

Have human health or ecological routes of exposure or receptors been newly identified or changed in a way that could affect the protectiveness of the remedy?

Air emissions from the stripper were evaluated for this 5YR. The OSWER Directive 9355.0-28, "Control of Air Emissions from Superfund Air Strippers at Superfund Groundwater Sites", stipulates that emissions in most need of control are those that exceed three pounds per hour (lbs/hr.) during any one hour, or fifteen pounds per day (lbs/day) during any twenty-four hour period, or a potential rate of 10 tons per year (tons/yr.) of total VOCs. Site VOC emissions were calculated at 9.13E-04 lbs/hr., 2.19E-02 lbs/day, and 8.0 lbs/yr. are below the emission limits stipulated in the OSWER Directive. The air stripper system is, therefore, in compliance.

In addition, EP As screening air dispersion model SCREEN3 was used to calculate the 1hr average and the annual average ambient air concentrations downwind of the air stripper. The maximu~ concentrations were estimated to occur at 390 meters (1279.5 feet) away from the air stripper exhaust point. The maximum annual ambient air average concentrations of the COCs were compared to the corresponding VOC concentrations from the November 2013 Residential Inhalation Risk Screening Level (RSL) Tables. The values from the RSL tables are calculated at a cancer risk of lE-06 and a non-cancer Health Index ofO.l. All of the annual ambient air concentrations are below the RSLs. For TCE, the maximum 1-hr concentration is also below the not-to-exceed Residential value of 2 µg/m3.


(


September 2014 20

The EPA RPM, Site toxicologist and Air/Superfund Coordinator performed a second vapor intrusion evaluation at the Site. The first evaluation was performed as part of the 2009 5YR. There are two industrial facilities (Bilcare Research, formerly IENOS Films, Inc. and Formosa Plastics, Inc.) above the eastern plume where vapor intrusion could potentially be a concern. No residential properties are present within the vicinity of either the western or eastern plumes. Formosa Plastics uses the same or similar volatile organic solvents or compounds as the contaminants of concern at the Site. Bilcare Research does not. The EPA RPM inspected both of these facilities to evaluate the potential for vapor intrusion. Formosa was inspected on April 8, 2014 as part of the Site inspection. Bilcare Research was inspected on April14, 2014. The evaluation and inspections are detailed in Appendix A.

Based on the characteristics of the buildings observed by the EPA, facility operations, and reviewed by the Site team, it was concluded that the vapor intrusion potential at the Formosa and Bilcare facilities was low to due to the following:

-Buildings at both facilities are built on intact thick concrete slabs which present very little potential for sub-slab vapors to migrate into the buildings.

-Buildings near the groundwater contamination on the Formosa property are naturally ventilated and not occupied except for limited time periods.

-The Bilcare office space has high-volume ventilation systems that has an air exchange rate of 6 times per hour. This systems ensure a safe working environment for the workers. These controls will also mitigate any potential accumulation of sub-surface vapors.

-Bilcare manufacturing area are very large with many natural ventilation points (such as windows and large bay doors) in addition to the high-volume ventilation systems to reduce heat. Bay doors are open year round.

However, these findings have not been confirmed by sampling. EPA, therefore, recommends that a vapor intrusion investigation be conducted to collect more data and information to support these findings.

Given the amount ofVOCs in the subsurface environment, vapor intrusion may also be a concern for any future buildings. Ifnew buildings are constructed in the plume area, they would need to consider this exposure pathway and plan accordingly. Conversely, as the remedial action continues to reduce the concentration of Site-related contaminants in groundwater beneath current and any future structures, the concern for exposure via vapor intrusion should be reduced as well.

Are there newly identified contaminants or contaminant sources?

No.

Currently only the three COCs are analyzed for during the annual performance



September 2014 21

monitoring. The last time the full suite ofVOCs were analyzed for all wells was in 1999. At that time Chloroform, Cis-1,2 DCE, Tetrachloroethane and 1,1,2-trichloroethane were detected at levels above current risk screening levels (RS Ls). All these detections in 1999 were in wells associated with the eastern plume. Concentrations of the VOCs in this area of active remediation are expected to decrease along with those of the COC chemicals.

( '

Are there unanticipated toxic byproducts of the remedy not previously addressed by the decision ' documents?

No.

Have physical site conditions or the understanding of these conditions changed in a way that could affect the protectiveness of the remedy?

During this 5YR period EPA became aware of investigations that were being conducted east of Schoolhouse Road at the Delaware City Refinery. Data from these investigations documented Delaware City PVC groundwater contamination beneath the refinery. EPA believes that these contaminants are part of the eastern plume documented at the Delaware City PVC Site.

EPA expressed these concerns in a November 20, 2013 letter to both Stauffer (now Bayer CropScience) and Formosa Plastics. A meeting to discuss this issue was held on May 9, 2014.

Have toxicity factors for contaminants of concern at the site changed in a way that could affect the protectiveness of the remedy? ·

Toxicity factors have changed since the 1986 ROD and the 1991 ESD. To determine whether the ROD performance standards for vinyl chloride (1 ug/L), 1,2 DCA (0.94 ug/L), and TCE (2.7 ug/L) are still protective a risk assessment was performed using current guidance and toxicity values. The non-cancer HI for adults and children were 0.3 and 0.4, respectively. These are below EPAs non-cancer threshold of 1.0(HI>1.0). The cancer risk is 2E-05. Cancer risk is primarily driven by vinyl chloride. EPAs acceptable cancer risk range is between lE-04 to lE-06. While other voes present in the groundwater could contribute some additional risk, their contribution is expected to be minimal. Therefore, the ROD goals for these three chemicals are still protective.

Air emissions from the stripper do not pose an unacceptable risk, based on estimates from current information.

Have other contaminant characteristics changed in a way that could affect the protectiveness of the remedy?

No.

Have standardized risk assessment methodologies changed in a way that could affect the protectiveness of the remedy?



September 2014 22

There have been significant changes in EP As risk assessment guidance since the 1986 ROD. These include changes in dermal guidance, inhalation methodologies, vapor intrusion, exposure factors, identification and assessment of mutagenic mode of action (MOA) contaminants and a change in the way early-life exposure is assessed for vinyl chloride. However, if one incorporates these new practices into an updated risk assessment, as discussed above, the ROD standards are still protective. Similarly, air emissions from the stripper do not pose an unacceptable risk, based on estimates from current information.

Changes in Standards and To Be Considered

Applicable or Relevant and Appropriate Requirements (ARARs) were not identified in the ROD for this Site since the ROD was issued prior to amendments to the Superfund statute requiring remedial actions attain ARARs unless a waiver is obtained. However, as part of the first 5YR, a list of potential ARARs was developed to help evaluate the protectiveness of the remedy. The State of Delaware has changed the MCL for TCE to 1 ug/l. With this exception, there have been no changes in these potential ARARs and to-be-considered at the Site. All potential ARARs associated with the discharge of treated effluent from the air stripper and the aeration basins are being met by the remedy. The groundwater cleanup standards for the Site have yet to be met. The list of potential ARARs is included in Attachment 5.

Question C: Has any other information com~ to light that could call into question the protectiveness of the remedy?

The remedy is protective in the short term for OUI and OU2 groundwater. However, complete characterization of the Site plume underneath the Delaware City Refinery has not been completed. Final determination of the long-term protectiveness of Site-related groundwater will be made in the next 5YR, following the evaluation of Site-related groundwater contamination underneath the Delaware City Refinery, and a determination ofhow this contamination will be incorporated into the remedy

Site area topographic maps were also compared to the State of Delaware's projected ranges of potential sea level rise. Projected potential sea level rise by the year 2100 of between 1.6 and 4.9 ft. are estimated by the State. The Site facility is mapped at greater than 50 feet above mean sea level. No negative impacts due to potential changes in sea level are expected.

Technical Assessment Summary

According to the data reviewed and the Site inspection, the remedy is functioning as intended by the 1986 ROD and the 1991 ESD. The air stripper continues to function within Superfund risk parameters and the pump and treat system continues to address the source area of the eastern plm:ne. Plans to fully evaluate the Site-related contaminants underneath the Delaware City Refinery will be developed. Only one monitoring well in the western plume (OW-10) has COC detection at or above the cleanup value in 2013. 1,2 DCA in this well was detected at 9.2



September 2014 23

ug/l, which is above the clean-up level of 0.94 ug/l. VC was detected at the cleanup level of 1 ug/ 1.

EPA also re-evaluated the potential for vapor intrusion to affect workers in structures above the plume ofVOC-contaminated groundwater in the eastern plume area. EPA has determined that there is little or no risk at this time. A more complete discussion of that process can be found in Section VII. Technical Assessment, Question B, and in Appendix A. However, these findings have not been confirmed by sampling. EPA, therefore, recommends that a vapor intrusion investigation be conducted to collect more data and information to support these findings.

Site-related contamination east of Schoolhouse Road has not been completely evaluated. Site groundwater contaminants comingle with contaminants resulting from refinery operations. No human receptors appear to be currently exposed· to Site-related contaminants beneath the refinery. Data collected at the refinery suggest that groundwater contamination discharges to Dragon Run Creek and does not migrate further south. No environmental evaluation of the impact of Site-related contamination to Dragon Run Creek has been completed. EPA will continue to monitor contaminant trends and develop a plan to address Site-related contamination east of Schoolhouse Road.

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


Forth Five-Year Review

September 2014 24

VI 11. Issues

Table 2 - Issues

Issue Currently Affects Affects Future Protectiveness Protectiveness (YIN) (YIN)

ySite-related contamination east of Schoolhouse N Road has not been completely evaluated.

yPotential for vapor intrusion into structures above N contaminated groundwater plume

IX. Recommendations and Follow Up Actions

Table 3 - Recommendat1ons/Follow-Up Actions

Issue Recommendations Party Oversight Target Affects I Follow-Up Responsible Agency Date -Protectiveness? Actions (YIN)

Current Future -

Site-related Fully evaluate the EPA will EPA September N y

contamination areal extent of pursue PRPs 10, 2019 in the contamination and for Columbia and potential impacts performance Upper to receptors of this work Potomac aquifer underlying Delaware City Refinery property

Develop remedial alternatives for this contamination

EPA will pursue PRPs for performance of this work

N y



September 2014 25 \

Issue Recommendations Party Oversight Target Affects I Follow-Up Responsible Agency Date Protectiveness? Actions (YIN)

Current Future

Potential vapor intrusion into structures above contaminated

PRP will collect additional data and information to assist this evaluation

Responsible Parties

EPA September 10,2016

N

N

y

y

groundwater plume

X. Statement on Protectiveness

The remedy for OU 1 is fully protective. The remedy has effectively reduced and/or eliminated the sources of Site-r~lated contaminants to groundwater. These actions included the excavation and removal of sludge 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 groundwater is protective in the short. Final determination of the long-term protectiveness will be made following the evaluation of Site-related groundwater contamination underneath the Delaware City Refinery. The remedy currently protects human health and the environment by effectively capturing and removing Site-related contamination from groundwater on the facility property, stopping the migration of Site-related contaminants in groundwater east of Schoolhouse Road. These measures have reduced the risk of exposure to Site contaminants and will continue until groundwater cleanup standards are achieved. Siterelated contamination east of Schoolhouse Road downgradient of the capture zone of the pump and treat system have not been completely evaluated. Site contaminants in the groundwater comingle with contaminants resulting from refinery operations. No human receptors appear to be currently exposed to Site-related contaminants beneath the refinery. Contamination appears to discharge to Dragon Run Creek and does not migrate further south. No environmental evaluation of Site-related contamination impacts to Dragon Run Creek have been done. EPA will fully evaluate and develop a plan to-address Site related contamination east of Schoolhouse Road.

Vapor intrusion into structures above the VOC-contaminated groundwater plume had called into question the protectiveness of the OU 2 remedy. In May and June 2009, EPA evaluated the potential for vapor intrusion with the owners/occupants of buildings that are located above the contaminated groundwater plume on the Formosa property and the current



September 2014 26

Bil care property. Both of these properties are west of Schoolhouse Road. These evaluations found little or no potential risk associated with vapor intrusion. This area was re-evaluated in April 2014. No changes in the buildings or operations have been identified to change these conclusions of protectiveness. Additional details can be found in Section VII. Technical Assessment, Question B, and in Appendix A. However, these findings have not been confirmed by sampling. EPA, therefore, recommends that a vapor intrusion investigation be conducted to collect more data and information to support these findings.

Overall, the Site is protective of human health and the environment in the short-term. Long-term protectiveness will be made following the evaluation of Site-related groundwater contamination east of Schoolhouse Road.

XI. Next Five-Year Review

The next 5YR for the Delaware City PVC Plant Site is required by September 2019, five years from the signature date of this review.

Appendix A and Attachments

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

'



September 2014 27

Appendix A

EPA Evaluations of Buildings above Contaminated Groundwater Plume

at Potential Risk for Vapor Intrusion

On April 8, 2014, the RPM and the DNREC Project Manager for the Delaware City PVC Site visited Formosa Plastics Corporation Delaware City facility at 780 School House Road, New Castle, Delaware to conduct an evaluation of the potential impact of possible for vapor intrusion due to the presence of the contaminated groundwater plume in the subsurface near and beneath sQme facility structures. The Delaware City facility is a subsidiary of Formosa Plastics Corporation, U.S.A. which is affiliated with Formosa Plastics Group in Taiwan. The Formosa Plastics facility in Delaware City is a leading producer of Specialty (Dispersion) PVC resins used by other plastics products manufacturers in a variety of products- including extruded films, sealants, inks, foams, liners, tiles, protective coatings.

The RPM reviewed a map of groundwater contamination at the Site and explained the potential for vapor intrusion associated with the Site to Formosa senior staff members Ms. Kimberly Bennett, Environmental Affairs Manager and Mr. Dan Piersimoni, Environmental Technician. The RPM and DNREC Project Manager toured the plant in the vicinity of the known contaminated groundwater plume with Ms. Bennett, including offices, production, storage and maintenance facilities and power equipment (e.g. chillers) buildings. Since the facility is quite extensive and construction and building functions were of uniform design and construction according to Ms. Bennett, EPA and DNREC toured representative buildings in this area. The three buildings closest to the plume are the service building, containing reverse osmosis equipment and compressors, the labor shop were workers take their breaks, and the S2 dryer building. Workers spend only limited time in these buildings.

There are no basements or below-ground crawl spaces anywhere in the plant according to Ms. Bennett. Furthermore, all buildings have poured concrete floors and any floor drains are piped to a wastewater collection and treatment area. During the inspection, all floors appeared to be structurally competent and well maintained and drains appeared to be in good condition. Typical production areas were on the second floor. All office/laboratory spaces are served by a year-round climate control system. All other structures feature abundant natural and/or powered ventilation of high-volume interiors. Formosa maintains solvents and other volatile organic compounds in quantity onsite. Some of these compounds are the same or similar to those associated with potential vapor intrusion at the Site.

On April 14, 2014, the RPM visited the Bilcare Research Inc. (Bilcare, formerly IENOS Film co., formerly VPI Mirrex Co.) to conduct an evaluation of the potential impact of vapor



September 2014

28

intrusion due to the presence of the contaminated groundwater plume beneath facility structures. Bilcare is located just east of the Delaware City PVC Plant Site at 1389 School House Road, New Castle, DE. Bilcare purchased the facility from IENOS in 2010, who took over the former VPI Mirrex Corporation facility in 2007. The facility still produces plastic pharmaceutical blister packs, plastic credit card stock, shrink wrap and various other plastic films used in the packaging industry Bilcare uses PVC powder extensively in their products. Bilcare describes their production approach in general as using some plasticizing compounds to render bulk PVC powder to a taffy-like texture, then extruding their products under the influence of heat and pressure. They report that none of their processes utilize volatile organic solvents or compounds including or similar to the contaminants of concern (viz. TCE, 1,2 DCA and VC) at the Site.

The RPM explained the potential for vapor intrusion assotiated with the Delaware City PVC Site to Mr. Scott Cudmore, Bilcare Safety, Health and Environmental. The RPM then toured the Bilcare facility with Mr. Cudmore.

The ground-level facilities (office space and production areas) are built on concrete slabs. The large production areas include powered ventilation fans near the interior roof line that are used primarily during hot weather. There are two exhaust over some of the production lines. Numerous large bay doors are also present in the production area. The offices and production areas are well-ventilated. Noticeable air movement was observed in both the production and office areas. No manufacturing was taking place during the time of this visit. A 2009 inspection noted that "heat produced by the production equipment was discemable but the temperature, humidity and ventilation control seemed quite adequate and the spaces were comfortable". Due to process heat, the bay doors are open year round.

A basement is present beneath part of the ground-level production area. The basement is large, but only occurs under approximately 15% of the production area. The basement areas extends down two-levels in some areas. Most of the basement area appears to be further that 100 feet away from the groundwater plume. Basement equipment consisted primarily of power, heating and chilling equipment and extensive pipe-runs. No production takes place in these areas. The entire space appears to be constructed of substantial concrete in good condition without obvious cracks or floor openings. There are large (~20 ft. x 40 ft.) openings between the first floor and basement. Large fans are used to reduce the heat and provide ventilation in the basement. There are numerous current and former liquid collection sumps in floors for condensate and waste collection. These are reportedly concrete-lined with no drainage below. Waste is drawn up from each floor sump by siphon pipes into collection tanks, and then pumped to treatment/collection out of the basement area. No sumps or basement areas are open to the subsoil. Only limited maintenance work lasting up to a few hours at a time is done in the basement.

The Bilcare office space is located within 100 feet of the groundwater plume. The HVAC ventilation in this area replaces the air within the office space six times per hour (air exchange rate = 6/hr). The HV AC system also controls ventilation in the break room, electrical control room, and pharmaceutical grade blister pack production area.



September 2014

29

Based on this inspection, the potential for entry of VOes from the subsurface groundwater contaminant plume and the potential for any significant human exposure appear minimal. Furthermore with the large amount of ventilation in the building, there is very little potential for vapor accumulation and thus for any significant human exposure. ·

In summary, the vapor intrusion potential at both the Formosa Plastics and Bilcare Research facilities is low to due to the following:

1. Both facility buildings have been built on intact, thick concrete slabs which present very little potential for sub-slab vapors to migrate into the buildings.

2. Both facility office buildings have high-volume ventilation systems. The Formosa facility uses these systems to control vinyl chloride and other voes from their production areas to ensure a safe working environment for the workers. The control ofvinyl chloride vapors and other voes will also mitigate any accumulation of sub-surface vapors.

3. The Bilcare production buildings are very large with many natural ventilation points (windows, large bay doors, etc.) in addition to the high-volume ventilation systems.

4. The industrial/office workers in both buildings are exposed for 8-ho~r work shifts per day, not the 24 hours that a resident may spend inside his/her home.

However, these findings have not been confirmed by sampling. EPA, therefore, recommends that a vapor intrusion investigation be conducted to collect more data and information to support these findings.



September 2014

30

Attachment 1- Site Location

s te Location Map Oellware City P'VC - Site Boundary

0 025 OS,,.Oeltw.,e City OE



September 2014

31

Attachment 2 - Generalized Map Showing Areas of Soil Remediation

Generalized Map Showing Areas of Soil Remediation

Soll Remediation Areas

A. PVC Resin Storage Area

B. Buried Sludge Pit

C. Aeration Lagoons

D. Off-grade Batch Pits

E. Unlined Ditches

F. Stormwater Reservoir

0 0.05 0.1

Mies



September 2014

32

------------------------------------------------------- -----

ATIACHMENT 3



September 2014

33

ATTACHMENT 3 (Cont.) Maps Depicting Locations of Contaminant Plume

1990-2013 Pa e 2of26



September 2014

34


1990-2013 Pa e 3 of 26



September 2014

35


1990-2013 Pa e 4 of 26



September 2014

36

ATTACHMENT 3 (Cont.) Locations of Contaminant Plume 1990-2013



September 2014

37


1990-2013 Pa e 6of26



September 2014

38


1990-2013 Pa e 7 of 26



September 2014

39

ATTACHMENT 3 (Cont.) icting Locations of Contaminant Plume 1990-2013



September 2014

40


1990-2013 (Pa e 9 of 26



September 2014

41



September 2014

42

ATTACHMENT 3 (Cont.) s Depicting Locations of Contaminant Plume 1990-2013 (Page 11 of 26)



September 2014

43


1990-2013 a e 12 of 26



September 2014

44

--------------------------------------------------



September 2014

45



September 2014

46


1990-2013 a e 15of26



September 2014

47



September 2014

48


1990-2013 Pa e 17 of 26



September 2014

49



September 2014

50

- -- - --------------------------------------------


1990-2013 a e 19 of 26



September 2014

51



September 2014

52

--------------------------------------------------------



September 2014

53



September 2014

54



September 2014

55



September 2014

56



September 2014

57



September 2014

58

ATIACHMENT 4

List of Documents Reviewed

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

-Explanation of Significant Differences, Delaware City PVC Superfund 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.

-Third 5YR Report, Delaware City PVC Superfund Site, Delaware City, DE, dated September 10,2009

-Potential Applicable or Relevant and Appropriate Requirements (ARARs) table, from 5YR Report, Delaware City PVC Superfund Site, Delaware City, DE, dated September 10, 2009

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

-Annual Groundwater Interceptor System Performance Monitoring Results for 2010, 2011, 2012, 2013 by Roux Associates, Stauffer remediation contractor

-Delaware City PVC Air Stripper Emissions Evaluation (for 5 Year Review): Email from Patricia Flores, Air Specialist, Air/Superfund Liaison, EPA Region 3 to Bruce Rundell, Remedial Project Manager, EPA Region 3, dated April15, 2014

-Risk Assessment Issues for Forth Five-Year Review, Delaware City PVC: Linda Watson, Toxicologist, Technical Support Section, EPA Region 3 to Bruce Rundell, Remedial Project Manager, EPA Region 3, dated April 29, 2014

-Preparing for Tomorrow's High Tide, Sea Level Rise Vulnerability Assessment for the State of Delaware, July 2012,

-Formosa Plastics Corporation monthly reports

-Quarterly reports submitted by A.C. Shultes, Inc., Stauffer O&M contractor



September 2014

59

-Memorandum of Agreement Department of Natural Resources and Environmental Control between Division ofAir and Waste Management and Division of Water Resources For: Delaware City Industrial Area, New Castle Co., Delaware, April 2008

(

--_--- ------------ --~ - ~-- ---::-=--------- - :::~-- --



September 2014

60

ATIACHMENT 5

List of Potential ARARs and To Be Cons1dereds (TBCs)

The ROD for this Site pre-dates the statutory requirement that remedial actions attain ARARs unless a wavier is obtained. Therefore 'there are no official ARARS for this site. As part of the first 5YR Report for the Delaware City PVC Superfund Site, Delaware City, DE, dated March 23, 1999, EPA evaluated the following potential ARARs and 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 Basin Commission (DRBC) Standards

These standards are listed as guide posts to help evaluate Site protectiveness and are not ARARs for the Site.

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

ARARorTBC Legal Citation Requirement Synopsis \

I. CHEMICAL SPECIFIC

Safe Drinking Water 40 CFR § Non-enforceable health goals Standard, Maximum 141.50-51 for public water supplies. Contaminant Level ,, The NCP requires that non-Goals (MCLGs) zero MCLGs shall be attained

by remedial actions for groundwater that is a current or potential source of drinking water, where the MCLGs are relevant and appropriate under the

' circumstances of the release.

Safe Drinking Water 40 CFR § Enforceable standards for ' ' Standard, 141.61-62 public drinking water supply

Maximum systems (with at least fifteen Contaminant Levels service connections or used (MCLs) ,by at least 25 persons). The



September 2014

61

ARARorTBC Legal Citation Requirement Synopsis

NCP ~equires that MCLs, for those contaminants whose MCLG is 'zero, shall be

J attained by remedial actions for groundwater that is a current or potential source of drinking water, where the MCLs are relevant and appropriate under the circumstances of the release. MCLs for VC, 1,2 DCA and TCE are 2.0 ppb, 5 ppb, and 5 ppb, respectively

)

Delaware Surface Delaware ' Criteria are provided to Water Quality Surface Water maintain surface water for '

Criteria Standards as Quality streams, lakes, rivers, and amended, February Standard~ as standing water in wetlands of 26, J993 amended, satisfactory quality consistent

February 26, with public health and ,

1993 Sections 3, recreational purposes, the 4, 5, 6, 8, 9, 10, propagation and protection of 11.1, 11.2, 11.3, fish and aquatic life, and 11.4, 11.6, and other beneficial uses of water. 12 water effluent

II. LOCATION SPECIFIC

Groundwater No Legal Citation Identifies groundwater quality to Protection Strategy of . be achieved during remedial 1984 EPA 440/6-84 actions based on aquifer 002

(

characteristics and use.

III.AGTION SPECIFIC

A. Air -

Control of Air No Legal Citation Policy to guide the selection of Emissions from Air controls for air strippers at Strippers at Superfund groundwater sites according to Groundwater Sites, the air qualify status of the site..,, June 15, 1989 EPA

~

--

- - -· l.Q~J!!!9l! Ji~~;-.:9~Q!!~ attainm~11t-=- -=-~--= or nonatta1nment area) - - - - -



September 2014

62

ARARorTBC OSWER Directive 9355.0-28

Delaware Regulations Governing the Control of Air Pollution

Clean Air Act

B. Water

Clean Water Act (CW A); National Pollutant Discharge Eliminat10n System

I Requirements

Delaware River Basin Commission (DRBC) Standards

'

Delaware Regulations Governing Control of Water Pollution, amended 6/23/83

Delaware RCRA

Legal Citation

DNRECAir Pollution Control Regulations Number 2, 19, and 24

Listed as hazardous air pollutants

40 CFR § 122.4l(e), 122.44, 122.45, 125.6163, 125 73

DRBC Groundwater Protected Area Regulation 4, Water Code of the Basin, Section 2.20.4

Delaware Regulations Governing Control of Water Pollution, amended 6/23/83 Sections 7,8,9,10,l l,12, and 13

Delaware Regulations Governing Hazardous Wastes 264.117, 264 228

Requirement Synopsis

Sets forth the requirement that a permit is necessary to operate an air stripper if emissions will exceed 2 5 lbs/day. Section 2 describes general conditions. Section 19 deals with odor. Sect10n 24 deals with volatile organic compounds.

Emission less ·than 10 tpy for individual HAP'and less than 25 tpy for combination HAPs.

Enforceable standards for all discharges to waters of the United States.

-

The operation1of a water withdrawal project shall not cause long-term progressive lowering of groundwater levels, permanent loss of storage capacity or substantial impact on low flows of perennial streams.

Contain water quality regulations for discharges into surface and groundwater.

Landfilling of waste. [30 year post closure care (mcluding prevent migration of liquids through landfill, promoting drainage and mmimize erosion



September 2014

63

ARARorTBC Legal Citation

Delaware RCRA 264.221, 264.227, 264.228

Requirement Synopsis of cover, accommodate settling, restrict post closure use of property as necessary, landfill closure and post-closure.

Operation of plant wastewater treatment system [prevent overtoppmg, monitoring for leaks, etc.]



September 2014

64