Records Collections | US Environmental Protection AgencyLIST OF ·ACRONYMS·...

FIRST FIVE-YEAR REVIEW REPORT FOR

OCCIDENTAL CHEMICAL SUPERFUND SITE

MONTGOMERY COUNTY, PENNSYLVANIA

August 2013

· Prepared by

U.S. Environmental Protection Agency

Region III

Philadelphia, Pennsylvania

,

Kathryn A. Hodgkiss, Acti g Hazardous Site Cleanup D U.S. EPA,'Region III

tnate

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Occidental Chemical First Five-Year Review Report August 2013

TABLE OF CONTENTS

LIST OF ·ACRONYMS·.................................. ~.~.......................................................................... iii

EXECUTIVE SUMMARY ...........................................................................................................v

FIVE-YEAR REVIEW SUMMARY FORM .................... · ....................................................... vii

1.0 INTRODUCTION ..............................................~............ ~..................................................!

2.0 SITE CHRONOLOGY ........................................ : ......................... : ........................ ~..........2

3.0 BACKGROUND ·············································-:·······························~···································6

3.1 PHYSICAL CHARACTERISTICS ...........................................................................6

3.2 LAND AND RESOURCE USE .................................................................................8

3.3 HISTORY OF CONTAMINATION ..........................................................................8

3.4 INITIAL RESPONSE AND BASIS FOR TAKING ACTION .................................9

4.0 REMEDIAL ACTIONS ..................................................................................................10

4.1 REMEDY SELECTION ........................................................................................... 10

4.1.1 1993ROD ..................................................................................................... ll

4.1.2 1995 ESD ................................................................................. : .................... 14

4.1.3 2008ESD ...................................................................................................... 14

4.1.4 2013 ESD ........................................... ; .. : ....................................................... 17

4.2 REMEDY IMPLEMENTATION ............................................................................. 18

4.2.l OU-1 Bedrock Groundwater Remedy Implementation ................................ 18

4.2.2 OU-2 Earthen Lagoons Remedy Implementation ...... : .... · ............................. 19

4.2.3 Drainage Swale and Sediment Pond Remedy Implementation ....................22

4.3 INSTITUTIONAL CONTROLS ............................................................................ ,.23

4.4 SYSTEM OPERATION AND MAINTENANCE ...................................................24

5.0 PROGRESS SINCE THE LAST FIVE-YEAR REVIEW...................•........................28

6.0 FIVE-YEAR REVIEW PROCESS ........................................................•.........................28

6.1 · ADMINISTRATIVE COMPONENTS ....................................................................28

6.2 COMMUNITY INVOLVEMENT ···························:···············································29 6.3 DOCUMENT REVIEW .............................................................................................29

6.4 DA TA REVIEW ................................................................................................ : ...... 30

6.5 SITE INSPECTION ..................................................................................................35

6.6 INTERVIEWS ...........................................................................................................36

7.0 TECHNICAL ASSESSMENT .......................................................................................... 36 ·

8.0 ISSUES...............................................................................................................................39

9.0 RECOMMENDATIONS AND FOLLOW-UP ACTIONS ............ ; .....•....................... .40

10.0 PROTECTIVENESS STATEMENTS............................................................................40

11.0 NEXT REVIEW ................................................................................................................40


TABLES

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

Table 2. 1993 ROD COCs and MCLs - Bedrock Groundwater ................................................. 12

Table 3. 1993 ROD COCs and Cleanup Levels - Drainage Swale and Sediment Pond ............ 13

Table 4. Cleanup Levels for the Earthen Lagoons (OU-2), 2008 ESD ........................................ 15

Table 5. 2013 ESD COCs. and MCLs - Bedrock Groundwater·······································:··········· 17

Table 6. NPDES GWRTS Discharge Limits and M01:1thly Sampling Requirements ................... 27

Table 7. Bedrock Wells with Site COCs > MCLs ........................................................................ 32

Table 8. Issues .............................................................................................................................. 39

Table 9. Recommendations and Follow-Up Actions ................................................................... .40

FIGURES

Figure 1. Location Map Figure 2. General Site Plan Figure 3. Site Plan - Groundwater Extraction and Treatment Figure 4. Process Flow Diagram- Groundwater Treatment System Figure 5. Bedrock Groundwater- Cross Section View Looking West Along Bedding Strike Figure 6. August 2012 TCE Concentrations in Bedrock Groundwater - Plan View Figure 7. August 2012 TCE Concentrations in Bedrock Groundwater- Cross Section View

Looking West along Bedding Strike Figure 8. Potentiometric Surface for the RW-ABC Pumped Interval - 11/30/2012 Figure 9. Potentiometric Surface for the RW-08 Pumped Interval - 11/30/2012 Figure 10. Potentiometric Surface forthe RW-06 Pumped Interval-11/30/2012

ATTACHMENTS

Attachment 1. Revised Site Delineation Attachment 2. December 2012 D_ischarge Monitoring Report Attachment 3. Site Inspection Checklist Attachment 4. Site Inspection Photographs

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µg/L ARAR CERCLA cis-1,2 DCE

. C.F.R. COPC CQAP DMR DPC EI.

EPA ESD FS FFS FSP FTR gpm GPRA GWRTS HHRA HRS IC JAEC LTTA MA/RH MCL mg/kg mg/L MSL NCP NPDES NPL O&M OU OxyChem PADEP PAH PCB PCE PCOR .PLC PMP

LIST OF ACRONYMS

Microgram per liter Applicable or Relevant and Appropriate Requirement Comprehensive Environmental Response, Compensation, and Liability Act cis-1, 2 Dichloroethene · Code of Federal Regulations Contaminant of potential concern Construction Quality Assurance Plan Discharge Monitoring Report Defense Plant Corporation Environmental Indicator U.S. Environmental Protection Agency Explanation of Significant Differences Feasibility Study Focused Feasibility Study Field Sampling Plan Firestone Tire and Rubber Gallons per minute , Government Performance and Results Act Groundwater Recovery and Treatment System Human Health Risk Assessment Hazard Ranking System Institutional Control Jacobs Aircraft Engine Company Low-temperature thermal aeration Mechanical aeration and radiant heat Maximum contaminant level Milligram per kilogram Milligram per liter Mean sea level National Contingency Plan National Pollutant Discharge Elimination System National Priorities List Operation and maintenance Operable unit Occidental Chemical Corporation Pennsylvania Department of Environmental Protection Polycyclic aromatic hydrocarbon Polychlorinated biphenyls Tetrachloroethene Preliminary Close Out Report Programmable logic control Performance Monitoring Program

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Occidental Chemical First 'Five-Year Review Report August 2013

POTW. PRP PVC QACR QAPP RA RAO RAP RAU RCRA RD RDWP RI ROD· RPM SCAD A SVE svoc SWCA TBC TCE trans-1,2 DCE U.S.C VCM voe WWTP

Publicly owned treatment works Potentially responsible party Polyvinyl chloride Quality Assurance Completion Report Quality Assurance Project Plan Remedial Action · Remedial action objective Remedial Action Plan Ready for Anticipated Use Resource Conservation and Recovery Act Remedial Design Remedial Design Work Plan Remedial Investigation Record of Decision Remedial Project Manager Supervisory Control and Data Acquisition Soil Vapor Extraction Semi-volatile organic compound Shallow wells liquid-phase carbon absorber To be considered Trichloroethene trans-1,2 Dichloroethene · United States Code . Vinyl chloride monomer Volatile organic compound Wastewater treatment plant

lV


EXECUTIVE SUMMARY

The final remedy selected by the United States Environmental Protection Agency (EPA) for the Occidental Chemical Superfund Site (the Site) included construction of a groundwater recovery and treatment system, operation and maintenance, performance monitoring, removal and off-site disposal of contaminated materials within the site's earthen lagoons, removal and off-site qisposal of contaminated soils and sediments within the site's drainage swale and sediment pond, and institutional controls. This is the first five-year review for the site, which is located in Lower Pottsgrove Township, Montgomery County, Pennsylvania. The action triggering this statutory review was the completion of construction, which is documented with the signing of the Preliminary Closeout Report on September 29, 2008.

The assessment of this five-year review found that the remedy was constructed and is operating in accordance with the Record of Decision, signed on June 30, 1993 as amended by three subsequent Explanations of Significant Differences. A June 29, 1995 Explanation of Significant Differences changed the method selected in the Record of Decision for disposal of certain material generated associated with the earthen lagoons remedy. Cleanup standards and remedy/disposal requirements for the earthen lagoons were further modified in an Explanation of Significant Differences issued by EPA on April 9, 2008. Modifications to the groundwater performance standards, the list of groundwater contaminants of concern and clarifications to the Site institutional controls are documented in an Explanation of Significant Differences issued by EPA on January 29, 2013.

The OU-I groundwater portion of the remedy is expected to be protective of human health and the environment at completion; in the interim, exposure pathways that could result in unacceptable risks are being controlled. The groundwater remedy is effective in reducing contaminant concentrations, and all groundwater with concentrations in excess of MCLs is hydraulically contained. The groundwater remedy is making demonstrable progress towards achieving clean-up objectives; however, contaminants remain in groundwater at concentrations·. which do not allow for unlimited use and unrestricted exposure. The Institutional Controls called for in the 2013 ESD should be implemented to ensure 1ong term protectiveness.

The OU-2 earthen lagoons remedy and the Site drainage swale/sediment pond remedy are protective of human health and the environment. The remedies are complete and were conducted as intended. All materials that exceeded the established cleanup standards have been excavated and disposed of off-Site, and the areas have been properly restored.

Government Performance and Results Act Measure Review

The Government Performance and Results Act holds federal agencies accountable for using resources wisely and achieving program results. As part of this five-year review, two environmental indicators (EI) and one land revitalization measure were reviewed. The status of these measures is presented below:

v


Performance Measure Progress Category/Status

Site-Wide Human Exposure EI Current human exposure is controlled.

Contaminated Groundwater Migration EI Contaminated groundwater migration is controlled.

Site-Wide Ready for Anticipated Use (SWRAU)

Conditions for SWRAU status have not been achieved.

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FIVE-YEAR REVIEW SUMMARY FORM

I SITE IDENTIFICATION

Site Name: Occidental Chemical

EPA ID: PAD980229298

NPL Status: Final

Multiple OUs? Yes (two)

Has the site achieved construction completion? Yes ·

REVIEW STATUS

Lead agency: U.S. EPA

Author name (Federal or. State Project Manager): Tim Gallagher

Author affiliation: U.S. EPA Region 3,

Review period: March 2013 - July 2013

Date of site inspection: April 4, 2013

Type of review: Statutory

Review number: 1

Triggering action date: September 29, 2008

Due date (five years after triggering action date): September 29, 2013

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Occidental Chemical First Five-Year Review Report August 2013 ,

Five-Yee1r Review Summary Form (Continued)

' Issues/Recommendations

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

Site Drainage Swale/Sediment Pond and the OU-2 Earthen Lagoons

Issues and Recommendations Identified in the Five-Year Review:

Issue 1 Issue Category: Institutional Controls (OU-1)

Issue: Institutional controls (IC) required by.the ROD, which protect the remedy components, are in plaee. However, I Cs clarified ,in the 20·13 ESD have yet to be recorded.

Recommendation: Implementation of the institutional controls via an environmental covenant. in accordance with the Commonwealth of Pennsylvania's Uniform Environmental Covenants Act.

Implementing Oversight Milestone Date Protectiveness Affect Current Affect Future

Party

No

Protectiveness Party

EPA 09/30/14PRPYes

- ·:.:~ ---------;-;-, -

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Five-Year Review Summary Form (continued)

I Protectiveness Statements

Operable Unit: Protectiveness Determination: Addendum Due Date: OU-1 Will be protective Not applicable

Protectiveness Statement: The OU-1· groundwater portion of the remedy is expected to be protective of human health and the environment at completion; in the interim, exposure pathways that could result in unacceptable risks are being controlled. The groundwater remedy is effective in reducing contaminant concentrations, and all groundwater with concentrations in excess of MCLs is hydraulically contained. The groundwater remedy is making demonstrable progress towards achieving clean-up objectives; however, contaminants remam m groundwater at concentrations which do not allow for unlimited use and unrestricted exposure. The Institutional Controls called for in the 2013 ESD should be implemented to ensure long term protectiveness.

Operable Unit: OU-2 and Site Drainage Swale/Sediment Pond

Protectiveness Determination: Protective Addendum Due Date:

Not applicable

Protectiveness Statement: The OU-2 earthen lagoons remedy and the Site drainage swale/sediment pond remedy are protective of human health and the environment. The remedies are complete and were conducted as intended. All materials that exceeded the established cleanup standards have been excavated and disposed of off-Site, and the areas have been properly restored.

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1.0 INTRODUCTION

The purpose of the Five-Year Review is to determine whether the remedy at a site is protective of human health and the environment. The methods, findings, and conclusions of reviews are documented in Five-Year Review reports. In addition, Five-Year Review reports identify issues found during the review, _if any, and identify recommendations to address those issues.

The U.S. Environmental Protection Agency (EPA) is preparing this Five-Year Review Report pursuant to Section 121(c) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Contingency Plan (NCP). CERCLA § 121 ( c) provides:

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 5 years after the initiation of such remedial action to assure ·that human health and the environment are being protected by the remedial action being implemented. In addition, if upon 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.

EPA interpreted this requirement further in the NCP at 40 C.F.R. §300.430(f)(4)(ii), which provides:

Ifa remedial action is selected that results in hazardous substances, 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 5 years after initiation ofthe selected remedial.action.

EPA Region 3 has conducted a Five-Year Review of the remedial actions implemented at the Occidental Chemical Superfund site (Site) in Lower Pottsgrove Township, Montgomery County, Pennsylvania. This is the first Five-Year Review for the Site. The action triggering this statutory review was the completion of remedial actions, which is documented as September 29, 2008. This review was conducted from March 2013 through August 2013 by the assigned Remedial Project Manager (RPM). This report documents the results of the review.

The Five-Year Review is statutorily required because the implemented remedy resulted in hazardous substances being left on the Site above levels that allow for unlimited use and unrestricted exposure.

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2.0 SITE CHRONOLOGY

Table 1 below summarizes site events in chronological order.

Table 1. Chronology of Site Events

Event Date

Jacobs Aircraft Engine Company (JAEC) operated on the Site and manufactured aircraft engines.

Prior to World

War II

The Defense Plant Corporation (DPC) purchased the Site from JAEC. 1942

JAEC continued to operate and manufacture aircraft engines for the DPC. 1942 to 1944

The DPC leased the Site to Firestone Tire and Rubber (FTR). 1945 to 1950

FTR purchased the Site from DPC in 1950, manufacturing tires and polyvinyl chloride (PVC) resins.

1950 to 1980

FTR sold the Site in 1980 to Hooker Chemicals and Plastics Corporation, which later became Occidental Chemical Corporation (OxyChem), who manufactured PVC resins at the site until 2005.

1980

FTR and OxyChem performed investigations at the Site and determined that elevated levels of trichloroethene (TCE) had migrated into bedrock groundwater.

' 1980 to 1983

Approximately 898 tons of soil contaminated with TCE was removed from the TCE handling area of the Site and was disposed off-site.

1984

EPA investigated the Site to characterize existing site conditions: Groundwater and sediment samples were collected and analyzed.

1985

EPA evaluated the Site using the Hazard Ranking System (HRS). TCE, trans-1,2-dichloroethene (1,2-DCE), and vinyl chloride monomer were identified as primary chemicals of concern at the Site.

1986-1987

The Site was added to the National Priorities List (NPL) of hazardous waste sites as a result of the presence ofTCE and related volatile organic compounds (VOC) in the bedrock aquifer.

' October 4, 1989

A ConsenfOrder was'-signea:oetweenEPA-and'Oxyehem,requiring OxyChem.~, to perform a Remedial Investigation (RI) and Feasibility Study (FS), sometimes referenced collectively as an RI/FS.

~ De~ember- 28-:-C989

OxyChem conducted an RI/FS to identify the nature and extent of contamination at the Site. The RI/FS was submitted to EPA in March 1993.

1990 to 1993

EPA issued a Record of Decision (ROD) selecting the final remedy. The final remedy required cleanup of three distinct areas of the Site: a contaminated bedrock groundwater plume (Operable Unit 1 [OU-1 ]), four unlined earthen lagoons containing PVC waste (OU-2), and contaminated sediments in an on-site drainage swale and sediment pond.

June 30, 1993

·

2



Event Date

EPA issued a Unilateral Order to OxyChem and Bridgestorie/Firestone, the

successor to FTR, directing OxyChem to implement the remedies detailed in June 23, 1994 the ROD.

·. OxyChem submitted a Remedial Design Work Plan to EPA in April 1995, 1995which was approved by EPA in July 1995.

OxyChem prepared a remedial design for the OU- I groundwater remedy. EPA 1995 to 1997 approved the remedial design in August 1997.

EPA issued an Explanation of Sigfiificant Differences (ESD) changing the

method selected in the ROD for disposal of certain material generated in the June 29, 1995 implementation of the OU-2 earthen lagoon remedy.

OxyChem submitted a remedial action plan to EPA for the OU-2 earthen. lagoons and conducted a pilot study using low-temperature thermal aeration

August 1996 to (L TTA) for drying the earthen lagoon PVC material for potential recycling.

March 1997 After bag house fires and other operating problems, OxyChem terminated the L TT A pilot test.

.. OxyChem submitted an Additional Flood Plain Investigation and Ecological Risk Assessment. Report. Based on sampling results of post-ROD soil, sediment, and sui:-face water samples, the report established background concentrations for ROD contaminants of concern (COC); identified new contaminants of potential concern; and concluded there was no ecological risk February 1997 from surface water and sediments within the site drainage swale and sediment pond, and in flood plain soils located adjacent to the closed site landfills. The report concluded that no further action was required to address the drainage swale, sediment pond, or flood plain.

OxyChem submitted an Alternative Technology Evaluation for OU-2 Earthen Lagoons to EPA and conducted a pilot study using Mechanical Aeration and Radiant Heat (MA/RH) for drying the earthen lagoon PVC material for

May 1997 to potential recycling. OxyChem subsequently submitted a report summarizing

December 1998 the pilot test ("Results of Mechanical Aeration and Radiant Heat Pilot Test for Earthen Lagoons PVC Material"). The report concluded that the use of MA/RH was not feasible.

OxyChem conducted the following activities: (I) prepared a Groundwater Remedial Action Plan and a Construction Quality Assurance Project Plan (approved by EPA in June 1997); (2) constructed the OU-I groundwater

June 1997 to treatment plant and groundwater recovery wells; and (3) established start-up

January 1999 and optimization measures for the treatment plant and recovery wells. EPA conducted a preliminary site inspection and the treatment system was considered ready to permanently go on-line in January 1999.

EPA issued a letter to OxyChem requesting additional information pertaining to

the February 1997 Flood Plain Investigation and Ecological Risk Assessment June 17, 1998 Report.

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Event Date

OxyChem provided additional information requested by EPA pertaining to the February 1997 Flood Plain Investigation and Ecological Risk Assessment November 6, 1998 Report.

OxyChem completed OU-1 groundwater remediation construction punch list January 1999 to

items. EPA and Pennsylvania Department of Environmental Protection May 1999 (PADEP) performed final inspections.

OxyChem requested that EPA issue an ESD for OU-2 to revise the clean-up criteria that were selected in the ROD for the soil underlying the earthen February 5, 1999 lagoons.

Based on results of the OxyChem Flood Plain Investigation And Ecological Risk Assessment Report and internal evaluations, EPA issued a letter to OxyChem requiring remediation of near surface soil and sediment in a portion June 30, 2000 of the site drainage swale where total polycyclic aromatic hydrocarbons (PAH) exceeded 5 milligrams per kilogram (mg/kg).

OxyChem submitted a Remedial Action Plan for Removal of Soil/Sediment August 7, 2000 . ..from the Site Drainage Swale.

Based on comments by EPA, OxyChem submitted a revised Remedial Action December I, 2000

Plan for Removal of Soil/Sediment from the Site Drainage Swale.

Based on OxyChem's pre-remedial action sampling data for the site drainage swale, EPA issued a letter to OxyChem recommending excavation of 2 feet of

May 29, 2001. soil/sediment within the area of the swale where sampling indicted results exceeding the clean-up criteria of 5 mg/kg fot PAHs.

OxyChem conducted additional sampling in the OU-2 earthen lagoons to better August 2001

characterize the PVC material and the underlying coal fines and soils.

EPA performed a Human Health Risk Assessment (HHRA) for the OU-2 earthen lagoons using the OxyChem August 2011 sampling results. Results of

August 2001 to the HHRA showed unacceptable risk to human health. In addition, results of a

April 2004 soil-to-groundwater analysis showed that contaminants in the lagoons could potentially-migrate tocthe.groundwatef. ___ . - - ~-.------· -·:--::--::-..-- - - ~ -·---. ·----· -OxyChem performed a remedial action within the site drainage swale. Approximately 200 tons of soil/sediment were removed and disposed of off-

November 2001 site. Excavation areas were restored with clean soil backfill and rip-rap stabilization.

OxyChem issued a Remedial Action Report for the Removal of Soil/Sediment December 2001

from the Site Drainage Swale.

OxyChem issued a Quality Assurance and Certification Report for the Groundwater Extraction and Treatment System. This report certified that the construction of the OU- I groundwater remedy extraction and treatment system May 2003 was performed in accordance with the requirements of the remedial design and approved changes.

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Event . Date

Dioxin sampling of earthen lagoon sludges that were involved in the thermal treatment pilot study.

December 2003

EPA conducted a review of the performance of the groundwater remedy and issued an Interim Report of Findings.

2004

EPA conducted a residential well survey and conducted residential well sampling for select private residential wells located on the other side of the Schuylkill River, within a 1-mile radius of the Site. EPA concluded that the residential wells were not impacted by Site groundwater COCs.

2004 to 2005

OxyChem performed a bedrock groundwater hydraulic testing program and other field activities at the site. OxyChem issued a 2005/2006 Summary of Findings Report to EPA on April 21, 2006, indicating that modifications to the groundwater treatment system pumping program could reduce potential vertical and horizontal migration of COCs from khown source areas and improve mass removal.

2005 to 2006

OxyChem entered into an Administrative Agreement and Order on Consent with EPA to conduct a Focused Feasibility Study (FFS) to re-evaluate the remedial action previously selected for the OU-2 earthen lagoons.

September 29, 2005

OxyChem submitted a Recovery Well Optimization Work Plan, which included a six-step phased approach to shut down select OU-1 recovery wells to optimize the treatment system pumping program. EPA approved the Work · Plan, and OxyChem subsequently implemented the optimization program with oversight by EPA.

2007 to 2012

Discharge of effluent from the OU-I groundwater treatment system was changed from conveyance to a local, publically owned treatment works to direct discharge on-site under a NOPES permit.

April 2007

OxyChem submitted a FFS for earthen lagoons that evaluated various clean-up options for OU-2 earthen lagoons. EPA subsequently approves the FFS Report.

March 2008

EPA issued an ESD (second ESD) changing the ROD in three ways pertaining to the OU-2 earthen lagoons. The ESD ( 1) selected a remedial alternative of excavation and off-site disposal of PVC wastes; (2) modified the clean-up levels for the lagoon soils; and (3) eliminated the required institutional control for the earthen lagoons because all PVC waste and soils not meeting the performance standards in the ESD will be disposed of off-site.

April 9, 2008

OxyChem submitted a Remedial Design/Remedial Action Work Plan to EPA for remediation of the OU-2 earthen lagoons.

June 2008

OxyChem performed remediation activities related to the OU-2 earthen lagoon. Remediation activities included excavation of PVC material, excavation of lagoon soils above clean-up levels, off-site disposal of PVC and soil materials, and site restoration. A total of44,135 tons of PVC and contaminated soil material were disposed of off-site in a permitted landfill (Horizon Environment Landfill in Grandes Piles, Quebec).

June 2008 to September 2008

5



Event Date

EPA issued a Preliminary Close-out Report indicating that the construction phase of the OU-1 and OU-2 remedy had been completed.

September 29, 2008

EPA conducted a final inspection for the construction phase of the 0Uc2 earthen lagoon remedy. \

November 24, 2008

OxyChem issued a Post-Construction Report for Earthen Lagoons to EPA. This report certified that construction of the OU-2 earthen lagoon remedy was

· performed in accordance with the project plans and specifications. February 13, 2009

EPA issued an ESD (third ESD) changing the ROD in three ways. The ESD ( 1) clarified the description of the Site and institutional controls that are still required for the Site; (2) changed the groundwater performance standards; and (3) added tetrachloroethene (PCE) and cis-1,2-dichloroethene (cis-1,2 DCE) as additional COCs for grou.ndwater at the Site.

January 29, 2013

3.0 BACKGROUND

This section describes the physical characteristics, land and resource use, history of

contamination, and initial response and basis for taking action for the Occidental site.

3.1 PHYSICAL CHARACTERISTICS

The Site is located on Armand Hammer Boulevard in Lower Pottsgrove Township, Montgomery County, Pennsylvania, within a meander of the Schuylkill River approximately 0.5

·mile southeast of the Borough of Pottstown (Figure 1). The site is bordered by the Schuylkill River to the south, eastand west. Site surroundings are both agricultural and urban.

The ROD describes the Site geographically by reference to the property owned by Occidental Chemical ("It consists of approximately 250 acres ...."), as well as by reference to a "disposal area" within that property. This "disposal area" consisted of: (i) a closed seventeenacre solid waste landfill, (ii) a seven-acre active industrial waste landfill, (iii) four inactive

. unlined earthen lagoons, (iv) two active lined lagoons, and (v) the TCE handling area. 1 EPA's remediai'act!on was limited to a narrow poftionof this-" disposal area;" namely~the-fourcunlined---.· -- ·-==:--·-~ earthen lagoons. The remedial action also addressed the contaminated groundwater plume and the drainage swale. Other portions of the "disposal area" were addressed by the Commonwealth of Pennsylvania's authorized program for hazardous waste management. The 17-acre solid waste landfill and 7-acre residual waste landfill were closed pursuant to Commonwealth of Pennsylvania regulations in 1985 and 1998, respectively. PADEP is the regulatory agency responsible for issues pertaining to the landfills; they are not being addressed under the

I Early Site investigations by Firestone and Occidental Chemical showed that the highest concentrations ofTCE in

groundwater were in the vicinity of the former "TCE handling area," which was where TCE was unloaded at the site

from railroad tank cars into a holding tank. During the unloading process, there was occasional spillage that caused

releases ofTCE into soils. In 1984, Occidental Chemical removed 898 tons of contaminated soils from the "TCE

handling area." According to the ROD, this removal reduced the releases ofTCE from the soil to the groundwater.

6


Superfund program. The permit for the solid waste landfill requires that OxyChem continuously pump groundwater beneath the landfills to prevent any contaminants from the landfills from moving off-site. The lined lagoons were closed under P ADEP authority in 1995-96.

Topography at the Site slopes gently downward from northwest to southeast toward the Schuylkill River. The highest elevation is approximately 190 feet above mean sea level (MSL) in the northwest comer of the property. The lowest site elevation is approximately 120 feet above MSL along the banks of the Schuylkill River. Surface drainage is generally outward in three directions from the center of the site towards the Schuylkill River. The southern portion of the Occidental property consists of a low-lying wooded area situated within the 100-year flood plain. Several drainage swales exist within the flood plain and receive general stormwater runoff from the Site. One of the swales had historically received discharge from a sediment pond located at the base of the residual waste.landfill. The landfill was closed in 1998 and, as part of the closure, the sediment pond was decommissioned. The drainage swale flows southeast until it discharges into the Schuylkill River. The drainage swale currently receives stormwater as well , as effluent discharge from the Site groundwater recovery and treatment system (GWRTS) under a NPDES permit.

A bedrock groundwater contaminant plume is present and is currently being remediated as part of the OU-1 bedrock groundwater remedy. The overburden soils at the Site consist of alluvium, fill, and weathered bedrock. The Site is underlain by sedimentary rocks of the Brunswick Group and the


approach to shut down select OU-1 recovery wells in order to optimize the treatment system pumping program. The Site currently contains a network of bedrock groundwater recovery and monitoring wells that are routinely monitored as part of the OU-1 operation and maintenance program.

3.2 LAND AND RESOURCE USE

Prior to the second World War, the Site was operated by JAEC, who manufactured aircraft engines. The DPC purchased the Site from JAEC in 1942. JAEC continued to operate and manufacture aircraft engines for DPC until late 1944. In 1945, DPC leased the Site to FTR, which subsequently purchased the Site in 1950. FTR manufactured tires and PVC resins at the Site. In 1980, FTR sold the Site to Hooker Chemicals and Plastics Corporation, which later became Occidental Chemical Corporation. OxyChem manufactured PVC resins at the Site until January 2005, at which time manufacturing operations ceased. Since 2005, the Site has undergone building and process demolition activities and decommissioning.

The Site property has been used for two purposes: commercial warehousing (northern portion of the property), and activities associated with implementation of the OU-1 groundwater remedy (southern portion of the property). Land use surrounding the Site property is agricultural, residential, and commercial. Land use across the Schuylkill River includes lowdensity residential -and commercial, agricultural to the southeast, and a nature preserve to the northeast. The Borough of Pottstown, Pennsylvania, is the closest major town located approximately 0.5 mile northwest of the Site. Approximately 31,000 people live within a 2:-mile radius of the site. The Schuylkill River, which bounds the Site property to the east, south, and west, is used both for water supply and for recreational activities.

EPA conducted a residential well survey in 2004 and identified numerous residential groundwater wells located within a I-mile radius of the site. EPA conducted groundwater sampling of select private residential wells located on the other side of the Schuylkill River and concluded that the residential wells were not impacted by the Site groundwater COCs.

3.3 HISTORY OF CONTAMINATION

~------The_w;;~_gfJ~CE at the Site began in the 1940s and continued when FTR produced PVC resins. TCE was phased-out o-f tlie-PVC production processin _1987~TGE-was-brought~toAhe~~--=-=- ~ Site in railroad tank cars and unloaded to a holding tank. The holding tank wa~ located aboveground and situated in a bermed retention basin where TCE was stored before its use in the PVC manufacturing process. TCE was added to the plant process water used in the PVC reactors. The spent reactor waste waters _were sent to an on-site industrial pre-treatment system before being pumped to the Pottstown publicly owned treatment works (POTW). Over the years of operation, the TCE transfer process from tank car to holding tank resulted in the release of TCE into the soils (through spills).

From 1979 to 1983, FTR and OxyChem sampled and analyzed process water wells to determine whether TCE had migrated from the unloading area through the overburden soils and into the groundwater via fractures in the underlying bedrock. Analytical results revealed the

8

Occidental Chemical First Five-Year Review Report August 2013 ·

presence of TCE in these wells at concentrations that exceeded the maximum allowed by the Safe Drinking Water Act (5 micrograms per liter [µg/L] TCE). The highest concentrations were detected in the TCE handling area of the Site where concentrations ranged from lO to 295 µg/L. In early 1984, approximately 898 tons of soil contaminated with TCE was removed from the TCE handling area and disposed of off-site. The removal of the contaminated soil reduced the movement of TCE from the soil to the groundwater.

A total of four unlined earthen lagoons (covering approximately 3 acres, total) present on the Site were used for storage of PVC sludge waste generated from the PVC manufacturing process. Throughout the operation of the earthen lagoons, sludge was first allowed to settle in the concrete holding basins located behind the wastewater treatment plant prior to being sent to the lagoons.- Un-polymerized PVC solids settled to the bottom of the basins. The supernatant water was skimmed off and sent directly to the Pottstown POTW. When a basin neared capacity, the PVC sludge was diverted to another lagoon. Sludge from the earthen lagoons was periodically removed and placed in the 1 7-acre solid waste landfill. FTR discontinued the use of the earthen lagoons in 1974 when two lined lagoons were constructed to handle the wastes. The earthen

· lagoons and their PVC contents were left in place. The lined lagoons were closed under P ADEP authority in 1995-1996.

Until 1990, the PVC sludge held in the earthen lagoons was not listed as a hazardous substance. On September 25, 1990, EPA expanded its list of hazardous waste to include some organic compounds. This list included vinyl chloride monomer; therefore, because of the change in waste classification, the PVC sludge earthen lagoons required closure.

A sediment pond, situated at the base of the residual waste landfill, collected stormwater runoff from the landfill during its operation. The sediment pond discharged to a drainage swale .. located in the Site flood plain, flowing southeast and discharging to the Schuylkill River. The residual waste landfill was closed in 1998 and, as part of that closure, the sediment pond was decommissioned.

In 1985, EPA Region 3 investigated the Site to characterize existing site conditions~ Groundwater and sediment samples were collected and analyzed. EPA evaluated the Site in 1988 using the Hazard Ranking System (HRS). The Site was assigned an HRS score of 45.91 and was placed on the NPL on October 4, 1989. EPA's evaluation identified the primary concern at the Site as t~e presence of several VOCs in the groundwater. The EPA investigation identified TCE, 1,2-DCE, and vinyl chloride monomer as primary chemicals of concern.

3.4 INITIAL RESPONSE AND BASIS FOR TAKING ACTION

On December 28, 1989, an Administration Order on Consent (Consent Order) was signed between EPA and OxyChem (Docket No. III-89-20-DC) for performance of a Rl/FS at the Site. OxyChem conducted the site-wide Rl/FS between 1990 and 1993; the Final Rl/FS report was issued in March 1993.

Data obtained during the RI were used to evaluate chemical migration routes and risks to public health and environment.· The primary focus of the RI was to determine the extent and fate


of contaminants at the Site, particularly TCE, in the bedrock groundwater. The RI involved site characterization sampling of alluvial soils and groundwater, Schuylkill River surface water and sediment, stormwater sewer outfall surface water and sediment, surface water and sediment from the Site sediment pond drainage swale, soil and sediment from the earthen and lined lagoons, and background soil. The RI also included plant community delineation, wildlife and habitat surveys, and a receptor evaluation. ·

During the RI, a human health risk assessment and an ecological risk assessment were performed for the Site. Results of the risk assessment indicated an unacceptable risk from bedrock groundwater and the earthen lagoon soil and sediments. In addition, concentrations of five principal chemical_s found in the groundwater exceeded the allowable levels under the Safe Drinking Water Act; that is, concentrations were greater than established maximum contaminant levels (MCL). An unacceptable risk was also determined from the Site sediment pond and drainage swale sediments to avian species. The sediment pond and the drainage swale were constructed features at the Site that were maintained for the purpose of capturing sediment and stormwater runoff from the active portions of the operating plant. The drainage swale directs stormwater runoff from the plant to the Schuylkill River. Based on the conclusions of the RI, EPA determined that potential risks to the environment from the sediment pond and drainage swale were unacceptable and warranted additional remedial action.

On September 29, 2005, OxyChem entered into a Settlement Agreement with EPA to conduct an FFS to evaluate clean.,up options for the earthen lagoons. The alternatives evaluated in the FFS included (1) on-Site disposal in-place, (2) on-Site disposal in a corrective action management unit, (3) international export and off-Site disposal, (4) off-Site disposal and incineration in the United States, and (5) off-Site recycling. The FFS included sampling of the lagoons· as well as areas outside of, and adjacent to, the lagoons. The FFS was approved by EPA in March 2008 leading to the 2008 ESD, discussed below.

4.0 REMEDIAL ACTIONS This section describes the selected remedies, remedy implementation, institutional

controls, and system operation and maintenance related to remedial actions at the Site.

The following decision documents have been issued for the Site, and are discussed hi -the· sections below: ·

• 1993 ROD

• 1995ESD

• 2008 ESD

• 2013 ESD

The 1993 ROD did not identify separate operable units (O_U) for the Site remedies.

10


·However, during post-ROD actions, the site groundwater remedy and the earthen lagoon remedy have commonly and informally been referred to as OU-1 and OU-2, respectively; therefore, these OU designations are also used in this Five-Year Report for consistency.

4.1.1 1993 ROD

Based on the findings of the site-wide 1990-1993 Rl/FS, the EPA issued and signed the ROD on June 30, 1993. The ROD identified the selected remedial action for the Site's bedrock groundwater (OU-1), the four earthen lagoons (OU-2), and the Site's drainage swale and sediment pond, which are described in the sections belO\v.

OU-1 Bedrock Groundwater Remedy

· The ROD stated that the principal threat posed by the Site is the groundwater contamination that resulted from former disposal practices and TCE handling operations. The specific remedial action objectives (RAO) listed below were developed to eliminate or reduce the potential for hazardous materials associated with the Site to impact human health and the environment:

• Restore groundwater in the bedrock aquifer to federal and state-applicable or relevant and appropriate requirements, including drinking water standards, to a level that is protective of human health and the environment.

• Protect non-impacted groundwater and surface water for current and future use.

Principal components of the remedy selected to achieve the RA Os were:

• Installation and operation and maintenance (O&M) of groundwater extraction wells to remove contaminated groundwater from beneath the Site and to prevent contaminants from migrating further.

• Installation and O&M of an air stripper to treat groundwater to the required levels.

• Installation and O&M of a vapor phase carbon unit on the air stripper.

• Periodic sampling of groundwater and treated water to ~nsure that treatment components were effective and that groundwater remediation was progressing towards the cleanup goals.

The ROD required numerous performance standards pertammg to the groundwater remedy, including standards for the groundwater extraction system, groundwater cleanup levels, air stripper and vapor phase carbon units, discharge of treated water, and periodic monitoring. The performance standard for groundwater cleanup levels for each COC was the MCL for that contaminant under the Safe Water Drinking Act (42 USC §§ 300f-300j-26), or the background concentration of that contaminant (in accordance with 25 Pa. Code §§ 264.90 to 264.100), whichever was lower. The background concentration for each COC was to be determined during the Site remedial design. The site groundwater COCs and their MCLs, as outlined in the ROD,

11


are listed on Table 2.

Table 2. 1993 ROD COCs and MCLs Bedrock Groundwater

Contaminant of Concern Cleanup Level a

Vinyl Chloride 2 µg/L

Ethyl benzene 700 µg/L

Styrene 100 µg/L

Trans-1,2,-Dichloroethene 100 µg/L

Trichloroethene 5 µg/L

Notes: a Equivalentto federal MCLs as promulgated under the Safe Drinking Wate.r Act at 40 CFR §§

141.61, and 141.62.

µg/L Micrograms per liter

The ROD required that the well system for extracting groundwater be operated until the performance standard for each COC is met and maintained through the entire area of the plume of contamination for a period of 12 consecutive quarters.

OU-2 Earthen Lagoons Remedy

The ROD indicated that the Site's four earthen lagoons present an unacceptable level of non-carcinogenic risk. The RI c~:mducted by OxyChem showed that the earthen lagoons . . contained VOCs and semivolatile organic compounds (SVOC) as a result of past disposal practices resulting from the PVC-manufacturing operations at the Site. Some of the .chemicals detected in the earthen lagoons include TCE; 1, 2-DCE; vinyl chloride; benzoic acid; and bis(2ethylhexyl) phthalate. These chemicals are all associated with the manufacture o'f PVC and are hazardous substances, as defined by Section 10 I (14) of CERCLA, and are listed at 40 CFR Part 302 in accordance with Section 102(a) of CERCLA. Arsenic was also considered a contributor to risk, according to the RI.

· The-specjfic RAO developed to eliminate or reduce the potential for hazardous materials associated with thesiUno-imp~ human health and the environment was to prevent migration of chemicals from the earthen lagoons-toc-grourid~ater or to surface water and to prevent direct contact with lagoon material. The ROD selectedaremedy for the OU-2 earthen lagoons that included (1) on-site drying and recycling of the PVC material; (2fland-filling of residual PVC material, coal fines, and contaminated soils from the earthen lagoons; and (3) ~esloration-.Qf the earthen lagoon area to original grade. · ~~ ·'0.

Principal components of the remedy selected to achievethe RAOs were:

• Construction of an access road to the earthen lagoons

• Excavation of PVC material (which includes all PVC sludge), coal fine layers,

12

http:esloration-.Qf


and contaminated soil

• Storage hopper for excavated materials

• On-site drying of PVC-material with air pollution controls I

• Dried PVC material shall be bagged, stored, and recycled

• Sampling and analysis as approved by EPA for transportation and disposal of

bottom coal fines layer oflagoons, including PVC residuals

• Sampling and analysis of underlying soils as approved by EPA to document

removal of chemicals of concern to backgrounq concentrations

• · Restoration of the area to original grade, which includes backfilling excavations

with clean fill

• Institutional controls

The ROD required numerous performance standards for the earthen lagoon remedy, including standards for drying and recycling of the PVC material contained by the lagoons; drying of PVC materials so that it is appropriate for recycling and no longer exhibits Resource Conservation and Recovery Act (RCRA) characteristics, air emission standards during drying, testing and off-site disposal of coal fines underlying the PVC material, testing and landfilling of PVC residuals that cannot be recycled, confirmatory sampling, and site restoration.

Drainage Swale and Sedimentation Pond Remedy

The remedy selected by the ROD required additional sampling during the remedial design to define the extent of cleanup required for the contaminated sediment found in the· sediment pond and drainage swale. The sediment was to be remediated to levels equivalent to the maximum Schuylkill River sediment background concentration detected during the RI, as outlined in Table 3.

Table 3. 1993 ROD COCs and Cleanup Levels Drainage Swale and Sediment Pond

Contaminant of Concern Cleanup Level

Total PAHs 5 mg/kg

Dibenzofurans 0 mg/kg

PCBs 0 mg/kg.

Mercury I 0.4 mg/kg

Notes: mg/kg Milligrams per kilogram PAH Polycyclic aromatic hydrocarbon PCB Polychlorinated biphenyls

In addition, further sampling of the flood plain to the south of the 17-acre solid waste

13


landfill and sediment pond/drainage swale was required to determine whether migration of contaminants had occurred during flooding events. Upon completion of the additional sampling, a full assessment of environmental risk and development of remedial objectives was to be completed. · ·

4.1.2 1995 ESD

On June 29, 1995, EPA issued an ESD changing the method selected in the ROP for disposal of certain material generated in the implementation of the remedy for the OU-2 earthen lagoons. Originally, the ROD provided that such material would be disposed of in an off-site landfill. Pursuant to the 1995 ESD, EPA allowed OxyChem to dispose of this material in an onsite 7-acre residual waste landfill. The material slated for such disposal included (1) recycling residuals that did not exhibit RCRA hazardous characteristics, (2) treated materials that no longer exhibited RCRA hazardous characteristics and met all applicable land disposal restrictions, (3) non-hazardous coal fines underlying the PVC material, and (4) treated coal fines that no longer exhibited RCRA hazardous characteristic and met all applicable land disposal restrictions. The 1995· ESD methods for disposal of the earthen lagoon materials were not implemented. The earthen lagoon materials were eventually disposed of off-site as required by the 2008 ESD.

4.1.3 2008 ESD

On April 9, 2008, EPA issued an ESD that made three significant changes to the 1993 ROD and the 1995 ESD. The first change modified the remedial action for OU-2 by selecting one of the remedial alternatives described in a FFS report prepared by OxyChem and approved by EPA on March 21, 2008. The second change modified the cleanup levels for OU-2 from background levels to standards established pursuant to the Commonwealth of Pennsylvania's Land Recycling and Environmental Remediation Standards Act, 35 P.S. § 6026.303. Both of these changes are described in the sections below. The third change eliminated the need for the required institutional control for the earthen lagoons because all PVC waste and soils not meeting the performance standards in the ESD were disposed of off-site.

Modification of Remedial Action for OU-2 After an evaluation of the alternatives proposed in the OU-2 FFS report, EPA determined that the remedy selected for OU-2 in the 1993.JlOD and the 1995 ESD needed to be modified. The modified remedy involved excavation of the PVC-matefiahmd-cany-mat~ria_~ssociated with the earthen lagoons and disposal in an offsite landfill. The modification involved the following-activities;-. --·=-c--___,~---

- ~ -~~-~~~~~·-

• The PVC material was to be excavated, solidified (as needed), and exported to Canada for disposal in an off-site landfill. The export of the PVC material and any other waste from the Site was to be in accordance with Section 3017 of the Solid Waste Disposal Act, 42 U.S.C. § 6938, and 40 C.F.R. Part 262, Subpart E.

• The cleanup standards in the earthen lagoon area are the standards established pursuant to Pennsylvania's Land Recycling and Environmental Remediation Standards Act, 35 P.S. § 6026.303, and promulgated in 25 Pa. Code Part 250. A list of the cleanup levels is provided in Table 4.

14


• Soils underneath or surrounding the PVC material and the coal fine layer were to be sampled after the removal of the PVC material. Any soils underneath or surrounding the PVC material, as well as any coal fines, that contain chemicals of cone.em in excess of the cleanup standards were to be excavated and disposed of off-site in a landfill. This material was to be disposed of in an off-site landfill in the United States in accordance with Section 121(d)(3) of CERCLA and Section 300.440 of the NCP. Otherwise, this material was to be disposed of in an

. approved Canadian landfill in the same manner as the PVC material, as described above.

• Soil from the berms surrounding the PVC material that contain chemicals of concern at levels below the cleanup standards were to be used to regrade the lagoons after all PVC material, and contaminated coal fines and soils are removed.

• Sampling of the area in the flood plain, outside of the earthen lagoons, showed no levels of contamination above the cleanup standards. However, OxyChem was to remove any PVC material from the flood plain and export it to Canada in the same manner as the PVC sludge in the earthen lagoons. Upon removal of the PVC material, the area was to be replanted utilizing a shade-tolerant wet meadow

. seed mix and appropriate tree and shrub species.

• After excavation and removal of any contaminated soils underneath and surrounding the PVC material and any contaminated coal fines, sampling and analysis of the remaining soils in the earthen lagoons was to be conducted to determine whether the cleanup standards have been achieved.

• Because all material from OU-2 that exceeds the cleanup standards was to be removed and disposed of off-site, no institutional controls were required for OU-2.

The earthen lagoon COCs and cleanup levels were established based on a human health risk assessment performed by EPA using data obtained during sampling of the earthen lagoon materials by OxyChem in August 2001. The earthen lagoon COCs and cleanup levels are provided in Table 4 ..

Table 4. Cleanup Levels for the Earthen Lagoons (OU-2), 2008 ESD

COCs Cleanup Level

(m2fk!!) Basis

Vinyl Chloride (a) 1.10 PA Site-Specific Standard (t)

Trichloroethene (a) 0.534 PA Site-Specific Standard (t)

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Occidental Chemical First Five-Year Review Report _ August 2013

Table 4. Cleanup Levels for the Earthen Lagoons (OU-2), 2008 ESD

COCs Cleanup Level

(me/k!!) Basis

Ethylbenzene (b) 10,000 PA Statewide Hea\th Standards (g)

Trans- 1, 2-Dichloroetherie (b) 292 PA Site-Specific Standard (f)

1-1 Dichloroethene (b) 6.4 PA Statewide Health Standards (g)

1-2 Dichloroethane (b) - 12 PA Statewide Health ·Standards (g)

Acetone (b) 10,000 PA Statewide Health Standards (g)

Benzene (b) 41 PA Statewide Health Standards (g)

Carbon Disulfide (b) 10,000 PA Statewide Health Standards (g)

Cis, 1-2 Dichloroethene (b) 43.9 PA Site-Specific Standard (f)

Methylene Chloride (b) (Dichloromethane)

4.97 PA Site-Specific Standard (f)

Tetrachloroethene (b) 89.1 PA Site-Specific Standard (t)

Toluene (b) 7,600 PA Statewide Health Standards (g)

Chloromethane (Methyl Chloride) (b)

180 PA Statewide Health Standards· (g)

Naphthalene (b) 4,400 PA Statewide Health Standards (g)

2,4 Dimethylphenol (b) 4,400 PA Statewide Health Standards (g)

2-Methylnaphtalene (b) 4,400 PA Statewide Health Standards (g)

4-Methyl 2-pentano11e (Methyl isobutyl ketone) (b)

19 PA Statewide Health Standards (h)

Bis 2-ethylhexyl phthalate (e) 130 PA Statewide Health Standards (i)

Phenanthrene (b) 10,000 PA Statewide Health Standards (i)

Thallium (e) 14 PA Statewide Health Standards U)

Cadmium (d) 38 PA Statewide Health Standards U)

- -~----,---Chromium (d)·.--..---.

94 PA Statewide Health Standards (k) - -:· ·~

Lead (c) -

------~50"=-- -c--, ,-,-;_PA Statewide Health Standards U)- --~ -~ -Nickel (b) 650 PA Statewide Health-Standards U).,..,...,,,_

Barium (b) 8,200 PA Statewide Health Standards U)

-

Notes: (a) Risk driver due to: Carcinogenic risk by soil ingestion for Future Resident (child and adult); Non-carcinogenic

Risk by soil ingestion for Future Resident (child); and potential groundwater contamination Soil-to-Groundwater pathway. ·

(b) Risk driver due to: Potential groundwater contamination Soil-to-Groundwater pathway. (c) Risk driver due to: Non-carcinogenic risk by soil ingestion for Future Resident (child and adult); and Potential

groundwater contamination/ Soil-to-Groundwater pathway. (d) Risk driver due to: Non-carcinogenic risk by soil ingestion for Future Resident (child); and Potential

groundwater contamination Soil-to-Groundwater pathway.

16


(e) Risk driver due to: Carcinogenic risk by soil ingestion for future Resident (child and adult); and Non

carcinogenic risk by soil ingestion for Future Resident (child).

(t) 25 Pa. Code Chapter 250, Subchapter F (250.601-606), Using EPA Soil Screening and Remediation Goals

Tool, Version l, 2006.

(g) 25 Pa. Code Chapter 250, Appendix A, Table 3A, Medium Specific Concentrations for Organic Regulated

Substances in Soil, Direct Contact Numeric Values, Residential. ·

(h) 25 Pa. Code Chapter 250, Appendix A, Table 38, IOOXGW Medium Specific Concentrations for Organics in

Soil, Soil to Groundwater Numeric Values, TDS < 2500, Residential.

(i) 25 Pa. Code Chapter 250, Appendix A, Table 38, Generic Value, Medium Specific Concentrations for

Organics in Soil, Soil to Groundwater Numeric Values, TDS < 2500, Residential.

G) 25 Pa. Code Chapter 250, Appendix A, Table 48, Generic Value, Medium Specific Concentrations for

Inorganic Regulated Substances in Soil, Soil to Groundwater Numeric Values, TDS < 2500, Residential.

(k) 25 Pa. Code Chapter 250, Appendix A, Table 4A, Medium Specific Concentrations for Inorganic Regulated

Substances in Soil, Direct Contact Numeric Values, Residential.

4.1.4 2013 ESD

On January 29, 2013, EPA issued an ESD that made three significant changes to the 1993 ROD. The first change was to clarify the description of the Site and the institutional controls required by EPA at the Site. The second change was to change the groundwater performance standards from the lesser of background levels or MCLs for each COC, to only the MCLs, anµ to require a cumulative risk evaluation once all MCLs have been met. The cumulative risk presented by all remaining Site-related compounds in the groundwater must be at or below EPA's level of unacceptable risk of lE-04 (1 in i0,000) cancer risk level; and the non-cancer HI, which .is the sum of the chemical-specific,· target-organ-specific, hazard quotients for these compounds, must be equal to or less than 1.

The third change was to add tetrachloroethene (PCE) and cis-1,2 DCE to the list of COCs in the groundwater. Routine groundwater sampling has demonstrated the presence of both of these contaminants above their MCLs. The final list of Site groundwater COCs and their MCLs are provided in Table 5.

Table 5. 2013 ESD COCs and MCLs - Bedrock Groundwater

Contaminant of Concern MCL 3

Vinyl Chloride 2 µg/L

Ethyl benzene 700 µg/L

cis-1,2 Dichloroethene 70 ug/L

trans-1,2 Dichloroethene 100 µg/L

Trichloroethene 5 µg/L

Styrene 100 µg/L

Tetrachloroethene 5 µg/L

Notes: 8 40 C.F .R. § 141.61 (July 30, 1992 ed. including amendments set forth therein).

17


4.2 REMEDY IMPLEMENTATION .

The Site remedy is being implemented by OxyChem. OxyChem submitted a Remedial Design Work Plan (RDWP) to EPA in April 1995. The RDWP was prepared pursuant to a Unilateral Administrative. Order (Docket No. III-94-26-DC) which was signed on June 23, 1994, and directed OxyChem to implement a remedial design and remedial action. The RDWP was approved by EPA in July 1995.

This section describes the elements of the selected remedy of the 1993 ROD, 2008 ESD, and 2013 ESD that have been implemented by OxyChem. Figure 2 shows a general site layout, depicting the locations of various Site remedy features.

4.2.1 OU-1 Bedrock Groundwater Remedy Implementation

In accordance with the RDWI>, OxyChem developed a remedial design for bedrock groundwater. The final remedial design set forth design drawings and technical specifications to govern equipment and. ·Construction procedures for the bedrock groundwater recovery and treatment system. EPA approved the final design in September 1997 and the Remedial Action Plan (RAP) on January 21, 1998. Construction of the bedrock remediation system commenced on March 17, 1998. OxyChem installed the groundwater recovery and treatment system in accordance with the requirements set forth within the Construction Quality Assurance Plan (CQAP) for Bedrock Groundwater Remedial Action, which was approved by EPA in June 1997. Periodic construction oversight was performed by EPA and EPA's oversight contractor.

The groundwater treatment plant is a metal-braced frame building that sits atop a concrete floor slab with secondary containment. The building houses the treatment system equipment, including equalization tanks, pre-treatment filters, air stripper, carbon adsorption tanks (aqueous and vapor), and all associated piping and mechanical and electrical equipment. The location of the treatment buildings is shown on Figure 2. The groundwater extraction system consisted of 11 recovery wells connected by force mains to the treatment system. Construction of the recovery wells included converting four existing groundwater monitoring wells to recovery wells, modifying two existing pumping·wells, and installing six new recovery wells. The original system included 12 recovery wells; however, well RW-2A was eliminated from the system due to high solids in the well. Well R W-8 wa~ redesigned to have an increased flow and.....,to 0"'remove-chemicals from the vicinity of R W-2A. High-density polyethylene underground piping was inst~liecf ~ithin utility trenches·to~transfer-:--flow_Jr~Qm Jhe recovery wells in two streams to the groundwater treatment plant. .Pump houses were constructed~for-tl:le"'-~.....,...--,...,-=recovery wells.

The major construction associated with the extraction and treatment system was completed by November 20, 1998. Initial treatment of groundwater began in March 1999, however, a system shakedown and optimization period continued through the duration of 1999, while assessment of treatment options for groundwater from three shallow recovery wells (R WA, RW-B and RW-8A) continued. OxyChem determined that these shallow recovery wells could not meet the influent requirements of the operating facility's reverse osmosis unit. Therefore, the flow from the wells was kept separate, filtered and carbon treated (for styrene adsorption), and then sent to OxyChem's facility wastewater treatment plant (WWTP).

18


Following treatment at the plant's WWTP, the water was discharged directly to the Publicly Owned Treatment Works (POTW). These shallow wells were brought online in February 2000, completing the construction of the extraction and treatment system. Discharge to the POTW ceased in April 2007 when direct discharge of effluent water on site was allowed under a NDPES permit by PADEP.

EPA conducted a site walkthrough inspection of the GWRTS on January 27, 1999. OxyChem completed construction punch-list items between January and May 1999, followed by a pre-final inspection by EPA on May 27, 1999. OxyChem prepared a Quality Assurance and Certification Report (QACR) for the GWRTS and submitted it to EPA in May 2003. The QACR certified that construction of the OU-1. groundwater remedy was performed in accordance with the requirements of the remedial design.

The GWRTS has been in full operation since January 1999. Because the operating PVC manufacturing facility used high-volume groundwater pumping for its processes, the GWRTS was configured to achieve the goals of the ROD and to supply water to meet the plant's high water demands. The volume of water required for manufacturing was greater than the groundwater remedy pumping requirements. Operations at the PVC manufacturing facility closed in January 2005; therefore, the high volume of groundwater withdrawal was no longer needed. Based on a review of the performance of the groundwater remedy by EPA in 2004, and closure of the manufacturing facility in 2005, OxyChem conducted a hydraulic testing program and concluded that modification to the GWRTS pumping program could reduce potential vertical and horizontal migration of COCs from known source areas and improve mass removal. OxyChem implemented a groundwater recovery optimization program from May 2007 to March 2012 that included a six-step phased approach to shut down select OU-1 recovery wells (RW-04, RW-05, RW-06 and RW-lOA) in order to optimize the treatment system pumping program. Recovery well R W-04 was restarted during the optimization program as a result of elevated levels (exceeding the MCL) of PCE within this well. The site currently contains a network of bedrock groundwater recovery and monitoring wells that are routinely monitored as part of the OU-1 operation and maintenance program.

The only permits that are required and that are in place for the OU-1 groundwater remedy is a NPDES permit for the discharge of the GWRTS effluent on-site to the site drainage swale. It was determined that an air permit for the discharge of vapor from the treatment system air stripper/vapor phase carbon absorbers was not required. This determination was made via a Request for Determination by OxyChem to PADEP on February 22, 2005, and approved by PADEP on October 21, 2005.

4.2.2 OU~2 Earthen Lagoons Remedy Implementation

The remedy selected by the ROD for OU-2 was not implemented for the following reasons: (1) difficulties encountered by OxyChem during remedial design pilot studies of the technology to be used for drying the potentially recyclable PVC material, (2) the feasibility of ultimately drying the PVC material in a cost-effective manner, and (3) market fluctuations for recycled PVC material.

19


In addition to the difficulties encountered in the remedial design for OU-2, on February 5, 1999, OxyChem requested that EPA issue an ESD to revise the clean-up criteria that were selected in the ROD for the soil underlying the earthen lagoons. OxyChem raised the issue that· arsenic in the earthen lagoons was not related to the PVC sludge in the lagoons, but to natural background conditions at the Site. Because arsenic was a contributor to risk, according to a risk assessment developed during the RI, EPA determined that it was necessary to conduct additional sampling of the earthen lagoons and prepare a HHRA:

OxyChem conducted additional sampling in the lagoons in August 2001 to better characterize the PVC material in the lagoons and to determine risks. Sampling was conducted at the surface of the lagoons and at varying depth intervals to bedrock. The EPA subsequently performed a HHRA for each of the lagoons .

. In December 2003, dioxin sampling was conducted on lagoon sludges that were involved in three separate baghouse fire incidents. The fires occurred during earlier pilot studies involving thermal treatment of the lagoon sludges. The sample analyses revealed that none of the samples exhibited levels greater than EPA's cleanup standard and a risk assessment was performed by an EPA toxicologist. To summarize the results, the risk calculation showed that the risk from dioxin was below EPA' s then-current industrial and residential cleanup levels. As explained below, all of the material in the lagoons was ultimately excavated and disposed of in ·a permitted Canadian landfill.

EPA then determined that it was necessary to conduct a FFS to re-evaluate the remediation options for the earthen lagoons. On September 29, 2005, EPA and OxyChem entered into an administrative agreement and order on consent, (Docket No. CERC-03-20050090DC) for performance of the FFS. On March 21, 2008, EPA approved Occidental's FFS Final Report, which evaluated various clean-up options for OU-2. The FFS also included sampling of an area outside of the lagoons, where PVC sludge was discovered in 2006. After an evaluation of the alternatives proposed in the FFS report, EPA determined that the remedy selected for OU-2 in the 1993 ROD and the 1995 ESD would be modified ..

In an April 2008 ESD, EPA selected three significant changes to the 1993 ROD and the 1995 ESD. The first change modified the remedial action for OU-2 by selecting excavation and disposal,-il).A_Canadian landfill, of the PVC sludge and any material associated with the earthen lagoons. The seconcfchange-riiodifiedthe clean:..up_l~yels for OU-2 from background levels to standards established pursuant to the Commonwealth ofPennsylvania's~band-Rec}'c;ling~-~1.gg Remediation Standards Act, 35 Pa. Con. Stat. § 6026.303. The third change eliminated the nee_d__-~~-~=-for the required institutional control for the earthen lagoons because all PVC waste and soils not meeting the performance standards in the ESD were disposed of off-site. The final earthen lagoons remedy, as required by the April 2008 ESD, is described in Section 4.1.3 of this Five-Year Review Report.

OxyChem submitted a Remedial Design/Remedial Action (RD/RA) Work Plan for remediation of the earthen lagoons in June 2008. The RD/RA Work Plan included the Construction Quality Assurance Plan (CQAP) and an Erosion and Sedimentation Control Plan. Another document that governed the earthen lagoon remediation was a Wetland Restoration Plan, issued in April 2008. EPA approved all of these documents. The specific steps of the

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remedial action consisted of the following:

• Mobilization

• Construction of an area to support the temporary office trailers

• Site preparation, constructing a working decontamination pad for equipment and

personnel, minor clearing and grubbing, and erosion and sediment controls

• Dewatering of the lagoons as required

. • Excavation, direct loading, and/or stockpiling of the PVC material in the four

earthen lagoons and from tlw layer of PVC in the adjacent flood plain to the

southeast side of the lagoons

• Excavation, direct loading, and/or stockpiling of contaminated soils from all four lagoons and from below the layer of PVC in the adjacent flood plain to the southeast side of the lagoons

• Retaining, scheduling, and coordinating trucks for transport of the PVC material and contaminated soils. Loading of trucks and transport. of PVC material and contaminated soils to the Horizon Environmental Landfill located in Grandes Piles, Quebec

• Stormwater management during all construction activities

• - Grading the site to satisfactory elevations

• Placement of topsoil, hydro-seeding, and placement of erosion control blankets

• Planting of trees and shrubs surrounded by a deer fence in the wetland area in accordance with the Wetlands Restoration Plan

• Demobilization

The locations of the earthen lagoons are shown on Figure 2. OnJune 11, 2008, the OU-2 Earthen Lagoon remedial action was initiated with the mobilization of the remedial action contractor to the Site. Excavation of the earthen lagoons commenced on June 25, 2008. Excavation began in the southeast lagoon and proceeded to the southwest and northwest lagoons, finishing with the northeast lagoon. ·Upon removal of the PVC material during excavation activities, confirmation (grab) soil samples were collected from the lagoon bottoms and sidewalls from locations within 50-foot by 50-foot grids, assembled within each individual lagoon. If any sampling results did not meet the Site clean-up criteria, the individual (non-compliant) grid was re-excavated to a depth of 6 to 12 inches and resampled. This process was repeated until compliance was met. The final truck of excavated materials was loaded on September 15, 2008. In total, 44, 135 tons of PVC and contaminated soils were loaded into 1,929 trucks and disposed of at the Horizon Environment Landfill in Grandes Piles, Quebec. Periodic construction oversight was performed by EPA and EPA's oversight contractor during RA implementation.

EPA conducted a pre-final inspection on September 26, 2008. A list of outstanding construction issues was prepared at the conclusion of the inspection. Outstanding issues

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included final preparation of topsoil, seeding, planting of trees and shrubs in the wetland area, mulching and other erosion control measures, and demobilization. Upon completion of all work, EPA conducted a final inspection on November 24, 2008.

OxyChem submitted a Post-Construction Report for Earthen Lagoons to EPA on February 13, 2009. This report demonstrated that construction of the OU-2. Earthen Lagoon remedy was performed in accordance with the design criteria, plans, and specifications presented in the RD/RA Work Plan, and performed in accordance with the Record of Decision:, as modified by the 2008 ESD.

4.2.3 Drainage Swale and Sediment Pond Remedy Implementation

The ~OD required additional investigation of the Site drainage swale, sediment pond; and other flood plain areas, followed by a full assessment of environmental risk and development · of remedial objectives. OxyChem prepared and submitted to EPA in April 1995 a RDWP, which included a discussion of the planned additional flood plain investigation and ecological risk assessment, and a field sampling plan (FSP) and quality assurance project plan (QAPP) to support the field sampling program. The plans were amended through correspondence with EPA and were approved by EPA on November 3, 1995. Final revisions to a Flood Plain Investigation and Ecological Risk Assessment Work Plan were provided to EPA on N overriber 8, 1995.

OxyChem collected soil, sediment, and surface water samples in Site flood plain areas. from locations selected in the field with EPA that represented areas of probable maximum deposition of transported sediment and soil. The specific areas investigated included the sediment pond, drainage swale, and the flood plain area adjacent to the closed landfill. Background samples were also collected. The sample analytical results were used to perform an ecological risk assessment. OxyChem submitted a Results of. Additional Flood Plain Investigation and Ecological Risk Assessment report in February 1997. The report established background concentrations for ROD COCs, identified contaminants of potential concern, and concluded there was no ecological risk from surface water and sediments within the Site drainage swale and. sediment pond, and flood plain soils located adjacent to the closed site landfills. The report concluded that no further action was required to address the drainage swale, sediment pond, or flood plain.

-~=-----·

Based on. results of the--OxyCnem--:--Flood.,...,Plain-,.Investigatio11__and Ecological Risk Assessment report and internal evaluations, EPA issued a letter to OxyChe~-on June-30, 2000'"'",~~requiring remediation of nearby surface soil and sediment in a portion of the Site drainage swale where total P AHs exceeded 5 mg/kg. As a result, OxyChem submitted a RAP for removal of soil/sediment from the Site drainage swale. The final report was submitted to EPA on December 1, 2000. In accordance with the RAP, OxyChem conducted pre-remedial action sampling of soil and sediment within the drainage swale to determine the final locations and total excavation depth that would be required within the swale. Based on OxyChem's pre-remedial action sampling data, EPA issued a letter to OxyChem on May 29, 2001, requiring excavation of 2 feet of soil/sediment within the area of the swale exceeding clean-up criteria of 5 mg/kg for PAHs, and stating post-excavation confirmatory sampling was not required. EPA further recommended that the excavation be backfilled with 1 foot of clean soil and then 1 foot of rip-rap to stabilize

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the swale.

Prior to excavation activities, OxyChem delineated the areas within the drainage swale to be excavated. On August 8, 2001, EPA conducted a site visit to review and approve the proposed excavation area. On November 12, 2001, OxyChem's remedial action contractor excavated the soil and sediment in the swale to. a depth of 2 feet below grade. Approximately 200 tons of soil/sediment were removed and disposed of off-site. Excavation areas were restored with clean soil backfill and rip-rap stabilization. The excavated soils and sediments were directloaded into dump trucks, transported, and disposed of at the BFI Conestoga Landfill in Morgantown, PA. The location of the segment of the drainage swale that was remediated is shown on Figure 2. OxyChem prepared the Remedial Action Report for Removal of Soil/Sediment from Drainage Swale and submitted it to EPA in December 2001.

4.3 INSTITUTIONAL CONTROLS

Institutional controls (IC) are administrative or legal controls that help protect the integrity of the remedy and help minimize the potential for human exposure to contamination by limiting land or resource use. They are generally used in conjunction with engineering measures such as groundwater remediation. Examples of ICs include easements, use restrictions on real property, and prohibitions on the use of groundwater or other resources. In Pennsylvania, ICs are now often implemented by the recording ·of an environmental covenant by the owner of an affected property in accordance with · the Commonwealth of . Pennsylvania's Uniform Environmental Covenants Act, 27 Pa. C.S. §§ 6501-6517.

The 1993 ROD called for two use restrictions. First, groundwater use at the Site for drinking purposes was prohibited. Second, the Site's. future use was limited to "industrial use only." These ICs were implemented in 1994 when OxyChem attached a copy of the June 23, 1994 Unilateral Administrative Order ·and a copy of the 1993 ROD to the property deed document and filed it with the Montgomery ~aunty recorder of deeds.

The 2013 ESD included clarification of the Site description and the ICs that are still required at the Site. The I Cs still required by EPA at the Site, as delineated on an aerial of the Site (Attachment 1 ), are a restriction of the Site to industrial use only and a prohibition on the use of groundwater for drinking purposes. The IC prohibiting the use of groundwater for drinking purposes applies to the portions of the property that are delineated by the shaded yellow . area on the Attachment 1 aerial; which approximates the boundary of contaminated groundwater plume above MCLs. The IC limiting the use of the Site to industrial purposes applies to the portions of the property that are delineated by the bold, green-lined shape on the Attachment 1 aerial (with the exception of the earthen lagoons area, represented on the Attachment 1 aerial as a blue-hatched area). ICs are not required for the earthen lagoon remedy or the drainage swale/sediment pond remedy because all materials associated with these remedies that exceed the established cleanup standards have been excavated and disposed of off-site. The ICs as clarified in the 2013 ESD have yet to be recorded with the Montgomery County Recorder of Deeds.

Since OxyChem recorded its deed notice with the Recorder of Deeds for Montgomery

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County in 1994, the Commonwealth of Pennsylvania has enacted a Uniform Environmental Covenants Act, 27 Pa. C.S. §§ 6501-6517, which may provide a clearer means of ensuring that use restrictions required at the Site run with ownership of the property. OxyChem has not recorded an environmental covenant · for the Site under the Commonwealth's Uniform Environmental Covenants Act at the time of this Five-Year Review.

4.4 SYSTEM OPERATION AND MAINTENANCE

OxyChem is conducting O&M activities for the GWRTS anq long-term groundwater monitoring activities at the Site in accordance with the Groundwater Extraction and Treatment System O&M Manual, which was updated on April 11, 2013. O&M activities are not required for the earthen lagoon remedy or the drainage swale/sediment pond remedy because all materials associated with these remedies that exceed the established cleanup standards have been excavated and disposed of off-site, and the areas have been properly restored. . Activities associated with O&M and performance monitoring are described in the sections below.

Operation and Maintenance

The primary activities associated with the ongoing O&M of the GWRTS include the following:

• Operation of the groundwater recovery and treatment system

• Inspections of the groundwater extraction system, including recovery wells and well houses

• Inspections of the groundwater treatment systems, including air stripper, shallow . well and raw water tanks and sand filters, liquid and vapor-phase carbon adsorbers, pumps, storage, and backwash tanks

• Monitoring of the GWRTS via the facility Supervisory Control and Data Acquisition (SCADA) system

• Influent and effluent testing of groundwater

• Effluent. testing of vapor from air stripper

• Influent and inter-bed testing of ground;~te~carbo.nbecfs-:--~_,~

• Discharge Monitoring Report preparation

• Maintenance of the GWRTS in accordance with manufacturer requirements in O&Mmanual

• Routine groundwater monitoring of site monitoring wells and recovery wells, and preparation of monthly and annual reports

OxyChem has been performing O&M activities for the GWRTS since 1999. Several GWRTS modifications have been made since its startup; the more substantial changes include:

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• Several changes to the GWRTS flow scheme were made after the PVC plant

operations ceased in 2005. The shallow groundwater treatment stream flow was

redirected from discharging to the plant's wastewater treatment plant to

discharging to the shallow well water tank. From this tank, the carbon-treated

shallow groundwater is pumped to the raw well water tank (which receives flow

from the remaining deep groundwater recovery wells) for subsequent air

stripping.

• Discharge of the GWRTS effluent to the POTW ceased in April 2007 when

discharge of the effluent to the Site drainage· swale was allowed under a NPDES

permit by PADEP. Liquid-phase carbon adsorbers were added to the treatment

stream by OxyChem as an air stripper effluent polishing step prior to on-site

discharge. ·

• Recovery wells RW-05, RW-06, and RW-lOA are no longer being pumped, as a

result of the groundwater recovery well optimization program that was conducted

by OxyChem from 2007 to 2012.

• The shallow well network (RW-A, RW-B, and RW-8A) was modified in 2009 to· provide separate lines from each well to the shallow well water tank.

• Because of the lack of styrene in pumped groundwater from R W-8A, the piping

for R W-8A was modified in 2011 to allow flow to either the shallow well water

tank (original design) or the raw well water tank. When recovery from RW-A

and RW-B exceeds the recommended minimum flow rate f

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