SDMS DocID 2093850

Five-Year Review Report

Second Five-Year Review Report for

Chem-Solv Inc. Site Cheswold, Kent County, Delaware

September 2008

PREPARED BY:

United States Environmental Protection Agency Region 3

Piiiiadelpiiia, Pennsylvania

Approved by; Date:

James Burke, Director Hazardous Site Cleanup Division U.S. EPA, Region 3

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 111

1650 Arch Street Philadelphia, Pennsylvania 19103-2029

SUBJECT:

FROM:

TO:

Five-Year Review Report, Chem-Solv Superfund Site, Cheswold, Delaware

'James W ih^A^^djAims''W¥eCXor )ffice eu Superfund Site Remediation (3HS20)

James J. Burke, Director Hazardous Site Cleanup Division (3HS00)

Enclosed for your signature is the second Five-Year Review report for the Chem-Solv Inc. Superfund Site ("Site") located in Cheswold, Delaware. The remedy for the Site included the collection and onsite treatment of contaminated groundwater until cleanup levels are achieved and the enforcement of groundwater use restrictions within the Groundwater Management Zone (GWMZ) established at the Site until cleanup levels are met.

The first five-year review for this Site was completed in September 2003.

The overall assessment of this five-year review found that the remedy was implemented in accordance with the requirements of the Record ofDecision. The remedy is functioning as designed and currently protects human health and the environment.

I recommend that you sign the attached Five-Year Review for the Chem-Solv, Inc. Superfund Site.

if J Printed on 100% recycled/recyclable paper with 100% post-consumer fiber and process chlorine free. Customer Service Hotline: 1-800-438-2474

Table of Contents

List of Acronyms iv Executive Summary v Five-Year Review Summary Form vi I. Introduction 1 II. Site Chronology 2 III. Background f. .4

Physical Characteristics , ...4 Land and Resource Use 4 History of Contamination 4 Initial Response 5 Basis for Taking Action 1....5

IV. Remedial Actions 6 Remedy Selection 6 Remedy Implementation 7 System Operation/Operation and Maintenance 9

V. Progress Since the Last Five-Year Review 10 VI. Five-Year Review Process 12

Administrative Components 12 Community Involvement 12 Document Review 12 Data Review 12 Site Inspection 19 Interviews 20

VII. Technical Assessment 20 Question A: Is the remedy functioning as intended by the decision documents? 20 Question B: Are the exposure assumptions, toxicity data . cleanup levels and remedial

action obiectives (RAOs) used at the time of the remedy selection still valid?... 21 Question C: Has any other information come to light that could call into question the

protectiveness of the remedy? 22 Technical Assessment Summary..-. 22 VIM. Issues 23 IX. Recommendations and Follow-Up Actions 23 X. Protectiveness Statement 25 XI. Next Review 26

Tables

Table 1 - Chronology of Site Events 2 Table 2 - Annual System Operations/O&M Costs 10 Table 3a - Quarterly TCE Concentrations in Groundwater 17 Table 3b - Quarterly Benzene Concentrations in Groundwater 18 Table 3c - Manganese Concentrations in Shallow Groundwater 19 Table 4 - Issues 23 Table 5 - Recommendations and Follow-Up Actions..... 23

Attachments

Attachment 1 - Maps Site Location Map Potable Supply Well Location Map Quarterly Groundwater Well Location Map'

Attachment 2 - Monitoring Well Contaminant Concentration Graphs Monitoring Well 9B Concentration Graph Monitoring Well 45B Concentration Graph Monitoring Well 8B Concentration Graph Monitoring Well 96-3-45 Concentration Graph Monitoring Well 96-4-45 Concentration Graph Monitoring Well 97-8-48 Concentration Graph

Attachment 3 - List of Documents Reviewed Attachment 4 - Applicable or Relevant and Appropriate Requirements (ARARs)

List of Acronyms

ARAR Applicable or Relevant and Appropriate Requirement

BTEX Benzene, toluene, ethylbenzene and xylene CERCLA Comprehensive Environmental Response, Compensation, and

Liability Act EPA United States Environmental Protection Agency CFR Code of Federal Regulations DNREC Department of Natural Resources and Environmental Control

ESD Explanation of Significant Difference GWMZ Groundwater Management Zone MCL Maximum Contaminant Level MCLG Maximum Contaminant Level Goal

NCP National Contingency Plan NPL National Priorities List \ O&M Operation and Maintenance PCOR Preliminary Close-Out Report POTW Publicly Owned Treatment Works PRP Potentially Responsible Party RA Remedial Action RAO Remedial Action Objective RBC Risk-Based Concentration

RD Remedial Design

RI/FS Remedial Investigation/Feasibility Study r

RPM Remedial Project Manager ROD Record of Decision SDWA Safe Drinking Water Act / TCE Trichloroethene UAO Unilateral Administrative Order VOC Volatile Organic Compound

IV

Executive Summary

The remedy for the Chem-Solv, Inc. Superfund Site (Site) in Cheswold, Delaware includes the collection and onsite treatment of contaminated groundwater until cleanup levels are achieved and the enforcement of groundwater use restrictions within the Groundwater Management Zone (GWMZ) established at the Site until cleanup levels are met. The trigger for this Five Year Review was the date of the first Five Year Review, September 26, 2008.

The assessment of this Five-Year Review found that the remedy was constructed in accordance with the requirements of the Record of Decision (ROD). One Explanation of Significant Difference (ESD) was issued in order to eliminate the requirement specified in the ROD that a notice be placed in the property records of properties located within the GWMZ at the Site. The remedy is functioning as designed. The immediate threats have been addressed and the remedy is expected to be protective when the groundwater cleanup standards have been achieved.

The remedy currently protects human health and the environment because exposure pathways that could result in unacceptable risks are being controlled. Institutional controls are preventing exposure to contaminated groundwater.

In order for the remedy to be protective in the long term, EPA will determine if an ESD should be issued to establish a cleanup standard for manganese which is protective of human health. In addition, a determination will be made regarding the need to provide additional treatment to remove metals from recovered groundwater in order to meet standards for discharge to surface water. Finally, the material in the on-site drum will be analyzed to determine the appropriate waste management option.

A vapor intrusion assessment was conducted in 2003, as a component of the first Five-Year Review for this Site; potential risks were determined to be unremarkable. Since 2003, the manner in which this pathway is evaluated has changed significantly but the conclusion reached for this Site remains unchanged. The State of Delaware Department of Natural Resources and Environmental Control (DNREC) is performing a Brownfield Site Investigation as part of the State redevelopment initiative. The findings will be presented in a final report due to be finalized by October 2008 and will be reviewed for potential changes to the screening assessment. As of the date of this report, there is no risk expected due to vapor intrusion at this Site.

As part of this Five Year Review the GPRA Measures have also been reviewed. The GPRA measures and their status are provided as follows:

Environmental Indicators Human Health: Human Exposure Under Control Groundwater Migration: Groundwater Migration Under Control Sitewide RAU: The Site was determined Site-Wide Ready for Anticipated Use (SWRAU) on June 26, 2006. ,

Five-Year Review Summary Form

SITE IDENTIFICATION

Site name: Chem-Solv, Inc.

EPA ID: DED980714141

Region: 3 State: DE City/County: Cheswold/Kent

SITE STATUS

NPL status: H Final D Deleted n Other (specify)

Remediation status (choose all that apply): D Under Construction Operating ^ Complete

Multiple OUs?* D YES la NO Construction completion date: 06/30/98

Has site been put into reuse? D YES a NO

REVIEW STATUS

Lead agency: H EPA D State D Tribe n Other Federal Agency

Author name: Christian W. Matta

Author title: Remedial Project Manager

Author affiliation: U.S. EPA, Region 3

Review period: 03/20/2008 to 09/25/08

Date(s) of site inspection: July 1, 2008

Type of review: El Post-SARA D Pre-SARA n NPL-Removal only D Non-NPL Remedial Action Site D NPL State/Tribe-lead D Regional Discretion

Review number: n 1 (first) El 2 (second) n 3 (third) n Other (specify)

Triggering action: D Actual RA On-site Construction at OU #_ • Construction Completion

• Other (specify)

• Actual RA Start at 0U# la Previous Five-Year Review Report

Triggering action date: 09/26/2003

Due date: 09/26/2008

VI

Five-Year Review Summary Form (continued)

Issues:

Several monitoring wells continue to have access problems due to being covered over by soil/gravel or by cars parked overtop.

Monitoring wells are not adequately secured.

The current health-based standard (Region 3 risk-based concentration or RBC) for manganese in drinking water is 780 ug/L. The 3,000 ug/L standard that was determined to be protective at the time the ROD was issued is no longer considered to be protective.

Compliance with surface water discharge standards for metals has not been verified.

' Assess the need to conduct periodic monitoring of air emissions from groundwater treatment system.

Unmarked abandoned drum found on site.

Confirm manganese not found in all wells.

Groundwater monitoring data indicative of source area unrelated to the Chem-Solv facility.

Recommendations and Follow-up Actions:

Reassess monitoring well network and develop a plan for maintaining access and ensuring wells are protected from damage. Establish.a point of contact with property owners on which monitoring wells are located.

Secure (bolt or lock) all monitoring wells.

Determine if an ESD is warranted in order to establish a protective cleanup standard for manganese in groundwater. ^

Determine if treatment to remove metals from recovered groundwater is necessary in order to meet discharge standards.

Determine if periodic monitoring of air emissions is warranted to ensure hazardous concentrations are not being emitted from groundwater treatment system.

VII

Review the findings of the Supplemental Brownfield investigation report to determine if the current assessment that there is no risk due to vapor intrusion is still valid

Determine if the unmarked, abandoned drum located on the Chem-Solv, Inc. property contains hazardous materials and, if so, dispose of the drum at an > appropriate hazardous waste disposal facility.

All wells monitored should have samples analyzed to identify manganese levels.

Review information and assess the potential for a source area not related to the Chem-Solv facility.

Protectiveness Statement(s):

The remedy currently protects human health and the environment because exposure pathways that could result in unacceptable risks are being controlled and institutional controls are preventing exposure to contaminated groundwater.

In order for the remedy to be protective in the long term, EPA will determine if an ESD should be issued to establish a cleanup standard for manganese which is protective of human health. In addition, a determination will be made regarding the need to provide additional treatment to remove metals from recovered groundwater in order to meet standards for discharge to surface water. Finally, the material in the abandoned drum will be analyzed to determine the appropriate waste management option.

A vapor intrusion assessment was conducted in 2003, as a component of the first Five-Year Review for this Site; potential risks were determined to be unremarkable. Since 2003, the manner in which this pathway is evaluated has changed significantly but the conclusion reached for this Site remains unchanged. There is currently no risk due to vapor intrusion. The State of Delaware Department of Natural Resources and Environmental Control (DNREC) is performing a Brownfield Site Investigation as part of the State redevelopment initiative. The findings will be presented in a final report due to be finalized by October 2008 and will be reviewed for potential changes to the screening assessment. As of the date of this report there is no risk expected due to vapor intrusion at this Site.

VIM

Chem-Solv, Inc. Superfund Site Cheswold, Delaware

First Five-Year Review Report

I. 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 them.

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

If the 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 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 Judgement of the 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 of facilities for which such review is required, the results of all such reviews, and any actions taken as a result of such reviews.

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

If a 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 five years after the initiation of the selected remedial action.

The United States Environmental Protection Agency (EPA), Region 3, conducted the five-year review of the remedy implemented at the Chem-Solv, Inc. Superfund site (Site) in Cheswold, Delaware. This review was conducted by the Remedial Project Manager (RPM) for the Site, from March 2008 through September 2008. This report documents the results of the review.

This is the second five-year review for the Chem-Solv, Inc. site (Site). The triggering action for this review is the signing of the first five-year review report indicating the review was completed on September 26, 2003. The five-year review is required due to the fact that hazardous substances, pollutants, or contaminants remain at the Site above levels that allow for unlimited use and unrestricted exposure.

II. Site Chronology

Table 1 - Chronology of Site Events

Event Date

Chem-Solv, Inc. conducted solvent recovery activities at Site 1981-1984

Explosion and fire occurred at the facility which resulted in a release of hazardous substances; Delaware Department of Natural Resources and Environmental Control (DNREC) issued Cessation of Operation Order 9/1984

DNREC conducted on-site treatment of soil contaminated with volatile organic compound (VOCs) 9-11/1985

DNREC conducted groundwater recovery and treatment operations 12/1985-11/1998

Final listing on EPA National Priorities List 8/30/1990

Remedial Investigation/Feasibility Study (RI/FS) and proposed remedial action plan made available to public 1/1992

Record of Decision (ROD) documenting selection of cleanup plan signed 3/31/1992

Unilateral Administrative Order (UAO) governing potentially responsible party (PRP) implementation of response activities issued 12/29/1992

Remedial Design initiated 2/22/1993

DNREC established a Groundwater Management Zone (GWMZ) in vicinity of the Site 3/1/1994

Remedial Design suspended pending evaluation of extent of trichloroethene (TCE) in basal portion of Columbia aquifer 2/8/1995

Remedial Design resumed (EPA notified PRPs of need for additional response actions) 10/18/1995

PRPs replaced two contaminated private water supply wells with wells in 10/1996 and deeper, uncontaminated aquifer. 1/1998

PRPs replaced remaining (uncontaminated) down gradient private water supply wells within GWMZ with wells in deeper, uncontaminated aquifer. 1/1998

Remedial Design approved by EPA (EPA approves PRPs' plans to carry out interim remedial measures) 5/28/1997

Remedial Action start 5/28/1997

Event

Construction start

Construction complete

Final inspection conducted by U.S. Army Corps of Engineers on behalf of EPA

O & M Plan approved by EPA

Remedial Action complete (EPA determined that PRP's interim remedial measures were sufficient to meet Remedial Action objectives specified in ROD)

Preliminary Close Out Report signed

EPA issued Explanation of Significant Differences (ESD) eliminating requirement for certain institutional controls

EPA approved PRPs' proposal to terminate groundwater collection and treatment at Site on condition that PRPs resume these activities in the event of increasing trends in groundwater contaminant concentrations

EPA directed PRPs to resume groundwater recovery and treatment operations

EPA directed PRPs to resume groundwater recovery and treatment operations

PRPs resume groundwater recovery and treatment operations

EPA signs first Five-Year Review

Date

7/31/1997

9/17/1997

9/18/1997

6/8/1998

6/10/1998

6/30/1998

6/18/1999

10/12/1999 .

3/4/2003

3/4/2003

11/5/2003

9/26/2003

III. Background

Physical Characteristics

The Chem-Solv, Inc. site (Site) includes a 1 Vi-acxe property that was formerly the site of a solvent recovery facility. The Site property is located in Cheswold, Delaware on the west side of U.S. Route 13 (Dupont Highway) just south of Delaware Route 42 (Attachment 1—Site Location Map). Cheswold is a community of approximately 300 residents, located in Kent County. In addition to the facility, the Site includes areas to the north and east where groundwater has become contaminated due to releases of hazardous substances from the facility. ;

Land and Resource Use

From 1981 until 1984, Chem-Solv, Inc. conducted solvent Tecoyery activities at the 1 Vz-acre property. Several structures are located on the property, including a residential building on the north-west portion of the property consisting of two or three occupied rental units, a small barn, a shed and the former Chem-Solv, Inc. office building which is abandoned and in poor condition.

The current land use for the surrounding area is residential and commercial. Private homes are located along Route 42 proceeding east from Route 13. Property to the west and south of the Chem-Solv property, formerly the site of a drive-in theater, has been developed within the last three years into an offiCe/light-industrial park and a baked goods outlet (Hostess). A vacant truck stop containing one building, now a home goods store called Green Seasons, is located on the parcel immediately north of the Site property. The Chem-Solv, Inc. property and the vacant truck stop property are currently being offered for sale. Several truck and automobile repair garages are located across Route 13, opposite the Chem-Solv property. It is anticipated that a mix of land uses similar to that described will continue into the future.

The aquifers underlying the Site serve as a water supply for local residences and businesses. In 1994, the Delaware Department of Natural Resources and Environmental Control (DNREC) established a Groundwater Management Zone (GWMZ) in the vicinity of the Site to prevent the installation of new water supply wells within the contaminated portion of the water table aquifer. The groundwater flow direction in the water table aquifer is to the northeast.

History of Contamination

The Chem-Solv, Inc. property is the location of a former solvent recovery facility. An explosion and fire at the facility in 1984 resulted in a solvent spill and contamination of soil and groundwater. Site investigations revealed that soils were contaminated with volatile organic compounds (VOCs) and the shallow Columbia aquifer was contaminated with VOCs, primarily trichloroethene (TCE), and localized elevated levels of manganese.

Underground storage tanks have been removed from several properties near the Chem-Solv, Inc. Site, including the former truck stop located immediately north of the Chem-Solv

property. Benzene, toluene, ethylbenzene and xylenes (BTEX) have been found in soil. BTEX and manganese have been found in groundwater at the former truck stop.

r •

Initial Response

In 1985, DNREC excavated and aerated 1,300 cubic yards of contaminated soil in order to remove the VOCs. This process addressed the soil contamination by reducing contaminant concentrations to levels that permitted the soil to be returned to the excavated area. To address groundwater contamination, DNREC also installed a groundwater collection and treatment system in 1985 and operated the system until 1988. The extraction of contaminated groundwater reduced TCE concentrations in the Columbia aquifer beneath the Site from the 250 milligrams per liter (mg/l) range to the 1 mg/l range.

The Site was initially proposed for the National Priorities List (NPL) on January 22, 1987, and finalized on the NPL on August 30, 1990. In January 1992, the Remedial Investigation/Feasibility Study (RI/FS) and the Proposed Plan identifying EPA's preferred remedy were made available to the public, starting the period for public comment.

Basis for Taking Action

Hazardous substances that have been released or detected at the Site in each medium include:

Soil Groundwater Benzoic acid Acetone

I Bis(2-ethylhexyl)phthalate Benzene Butylbenzylphthalate 1,1 - Dichloroethane 1 - Chioroethane 1 ,2 - Dichloroethane Chloroform cis -1^2 - dichloroethene 1, 2 - Dichloroethane Manganese DDD Methylene chloride DDE Tetrachloroethene -, DDT Toluene Ethylbenzene 1, 1, 1-Trichlorethane Isophorone Trichloroethene Methylene chloride Xylenes Toluene 1,1,1 -Trichlorethane r Trichloroethene Xylenes

The baseline human health risk assessment conducted during the Remedial Investigation (RI) indicated that long-term exposure to contaminated groundwater at the Site would result in unacceptable human health risks. Cancer risk was attributed mainly to the presence of benzene and TCE. Noncancer risk was due to the presence of manganese.

The presence of dissolved manganese in groundwater is believed to be the result of the contaminants being in the aquifer.

Based on the RI, EPA concluded that exposure to on-site soils would not present an unacceptable risk to human health or the environment.

IV. Remedial Actions

Remedy Selection

The Record of Decision (ROD) for the Chem-Solv, Inc. site was signed on March 31, 1992. Remedial Action Objectives (RAOs) were developed as a result of data collected during the RI to

aid in the development and screening of remedial alternatives to be considered for the ROD. the RAOs for the Chem-Solv, Inc. site are to:

1. Restore groundwater to its beneficial use as a potential drinking water source by reducing contaminant levels to Maximum Contaminant Levels (MCLs) and non-zero Maximum Contaminant Level Goals (MCLGs) established under the federal Safe Drinking Water Act and, where MCLs and MCLGs are not available, to levels determined by EPA to be protective of human health; and

2. Prevent exposure to the contaminated groundwater until the restoration is complete.

The major components of the remedy selected in the ROD include:

1. Collection of contaminated groundwater using recovery wells located in the contaminated portion of the Columbia aquifer until cleanup levels are achieved;

2. Discharge of extracted groundwater to the local publicly owned treatment works (POTW) via the Kent County sewer system or, if an agreement with the POTW cannot be reached, on-site treatment of extracted groundwater and discharge of treated groundwater to local surface water;

3. Continued groundwater monitoring at domestic, recovery and monitoring wells until cleanup , levels are achieved;

4. Provision of an alternate water supply for users of private water supply wells should any become contaminated before the groundwater restoration is complete;

5. Establishment and enforcement of a State Groundwater Management Zone (GWMZ) to prevent the installation of water supply wells within the contaminated portion of the Columbia aquifer until cleanup levels are achieved;

6. Placement of a notice of the GWMZ in the property record of all properties located within the GWMZ until the cleanup levels are achieved; and >

7. Removal of existing recovery wells and establishment of new recovery wells.

6

An ESD was issued on June 18, 1999 in order to eliminate the requirement that a notice be placed in the property records of the properties located within the GWMZ. EPA determined that such notices were no longer necessary to alert prospective purchasers of property within the GWMZ to the potential for contamination of the property dnnking water supply well.

With one exception, all drinking water wells located in the contaminated portion of the Columbia aquifer were replaced with water supply wells in a deeper, confined aquifer which has not been affected by releases from the Site. Review of the records found that the June 18, 1999, ESD documents that a shallow drinking water well still supplies residence on the former Chem-Solv, Inc. property, which is located within the GWMZ. In February 1993, a copy of the Administrative Order, Docket No. III-93-11-DC, for performance of the RD/RA along with a copy of the ROD was recorded by the Recorder of Deeds for Kent County, Delaware. This will ensure conditions at the Site are brought to the attention of any person examining the title to the property where the former Chem-Solv, Inc. facility was located. During the 2008 Five-Year Review Site visit a potable supply well was identified as still being in use at the small residential building located on the rear of the property formerly used for the Chem-Solv Inc., operations. This well was not included in the annual sampling because it is hydraulically upgradient from the groundwater plume. The well is scheduled to be sampled and then removed as part of the redevelopment initiative being overseen by DNREC.

Remedy Implementation

On December 29, 1992, EPA issued a Unilateral Administrative Order (UAO) to 33 Respondents, requiring them to design, construct, operate and maintain the selected remedy. Respondents abandoned existing monitoring and recovery wells which were not needed for monitoring purposes in November 1993 and April 1999. EPA approved the design for the new groundwater extraction and on-site treatment system on May 28, 1997. Respondents awarded the Remedial Action (RA) contract to Rare Earth Envirosciences, Inc. (Rare Earth) on May 28, 1997.

Construction of the groundwater recovery and treatment system began on July 31, 1997, when an air stripper was delivered to the Site, and was completed on September 17, 1997. No construction deficiencies were noted during the final inspection conducted by Rare Earth, the U.S. Army Corps of Engineers on behalf of EPA, and DNREC on September 18, 1997.

Continuous operation of the groundwater recovery and treatment system began on October 10, 1997 after EPA and DNREC confirmed the efficiency of the air stripper in removing VOCs from influent groundwater. Rare Earth submitted an Interim Remedial Action Report to EPA and DNREC on December 2, 1997 in order to document completion of physical construction of the groundwater,recovery and treatment system. On May 19, 1998, following review of Rare Earth's April 24, 1998 Interim Report documenting system performance, EPA and DNREC jointly determined that the RA was operational and functional. With the signing of the Preliminary Close Out Report (PCOR) on June 30, 1998, construction completion was achieved.

By 1999, groundwater quality at the Site had substantially improved. In July 1999, only one well monitoring well had TCE concentrations exceeding the cleanup standards. The well was

located on the Chem-Solv, Inc. property and had a TCE concentration of 41 ug/L. Manganese concentrations in groundwater exceeded the cleanup standard only in isolated areas beneath the former Chem-Solv, Inc. property and immediately down gradient from the former truck stop.^

On August 20, 1999, Respondents proposed the termination of groundwater collection and treatment operations with continued groundwater monitoring in order to document anticipated continuing declines in TCE concentrations. EPA approved the proposal on October 12, 1999 with the stipulation that the Respondents resume operation of the groundwater collection and treathient system should an increasing trend in TCE concentrations be identified.

On March 4, 2003, EPA determined that TCE concentrations had not declined and based on results of monitoring well samples collected since the treatment system was shut off; determined that TCE concentrations were exhibiting a statistically significant increasing trend in two Site monitonng wells. As a result, EPA requested that the Respondents resume treatment of groundwater. The EPA also requested that the Respondents analyze groundwater samples for 1,4-dioxane (Dioxane).^ >

In June 2003, the PRPs proposed certain modifications to the groundwater collection system in order to more efficiently remediate the Site. These modifications consisted primarily of collecting groundwater from the location exhibiting the highest TCE concentrations, and increasing the withdrawal rate by using two recovery wells. The proposed recovery wells (MW-96-5-48 and an adjacent unused private well (Old Williams well)) are located approximately 200 feet upgradient of the original recovery well (See Attachment 1 - Quarterly Groundwater Well Location Map). The proposed collection system modifications also included a contingency to allow collection of groundwater from the original recovery well, should such collection be deemed appropriate. No modifications to the groundwater treatment system were needed because flow rates were all within the originafdesign parameters. The Agency approved the collection system modification in August 2003 and groundwater recovery operations resumed in November 2003.

Groundwater samples were collected and analyzed for 1,4-dioxane per EPA's request. In July 2003 the Respondents submitted the results of the analysis which indicated that 1,4-dioxane

In some cases insoluble manganese (III) and manganese (IV) within the aquifer matrix is used as an electron acceptor during anaerobic biodegradation of organic carbon. During this process the manganese is reduced to water soluble manganese (M). It is believed that releases of organic compounds at the Chem-Solv, Inc. site and the adjacent former truck stop are responsible for

the reduction and solubilization of manganese. Once the organic groundwater contaminants are remediated, and oxygen is reintroduced into the aquifer, it is expected that dissolved manganese levels will decline to acceptable background levels.

^Historically, the presence of 1,4-dioxane has not been routinely evaluated during hazardous site investigations. It is only within the past few years that improvements to analytical methods at the commercial level have made it possible to reliably detect and quantify 1,4-dioxane. Because 1,4-dioxane was once commonly used as a stabilizer for chlorinated solvents such as TCE, which is present at the Chem-Solv, Inc. site, EPA requested that the PRPs evaluate the presence of 1,4-dioxane in groundwater at the Site. EPA Region 3's risk-based concentration (RBC) for 1,4-dioxane in tap water is 6.1 ug/L. Residential exposure to this concentration in tap water is associated with an excess lifetime cancer risk of a 1 X 10'*.

was not present in any of the samples.^ As a result no changes to the treatment system were needed to address 1,4-dioxane contamination.

EPA and the State have determined that all RA construction activities performed to date, as well as the implementation of institutional controls, were performed according to specifications. It is expected that cleanup levels for all organic groundwater contaminants will be reached within approximately ten years. EPA expects dissolved manganese concentrations to decline as organic carbon is depleted from the aquifer and aerobic conditions are restored. '

The time frame for attaining levels of manganese that are protective of human health cannot be estimated based on the existing data base. Additional data will be collected as a result of this Five-Year Review to assess the status of the manganese concentrations in the groundwater plume and the need to modify the treatment system and or establish a site specific cleanup level for manganese. " ^

Once the groundwater cleanup levels have been met and no further groundwater treatment is necessary, EPA will issue a Final Close Out Report.

System Operation/Operation and Maintenance

The Respondents are conducting long-term monitoring and maintenance activities according to the operation and maintenance (O&M) plan that was approved by EPA on June 8, 1998. The primary activities associated with O&M have included the following:

• Collection of contaminated groundwater from well MW-96-6-48 (from September 1997 to October 1999);

• Treatment of recovered groundwater in a shallow tray air stripper;

• Discharge of treated groundwater to the local storm sewer;

• Monthly inspection of treatment system and appurtenances;

• Quarterly monitoring of the effluent from the air stripper; and

• Quarterly monitoring of groundwater.

Prior to 2003, the highest TCE concentrations in the Columbia aquifer occurred upgradient of the pumping well MW-96-6-48. As a result the collection system modifications were implemented and beginning in November 2003, the Respondents began collecting groundwater from two wells (MW-96-5-48 and a nearby former water supply well) located hydraulically upgradient of MW-96-6-48. Well MW-96-6-48 remains connected to the groundwater collection

The laboratory quantitation limit for these analyses was 11 ug/L, i.e., well below the concentration in tap water that would present an unacceptable risk, i.e., an excess lifetime cancer risk greater than 1X10 . - • t

system so that it may be used for recovery of contaminated groundwater in the future, if necessary.

O&M costs include operation of the groundwater recovery and treatment system as well as the sampling and monitoring efforts except for the period of October 1999 through July 2003. During that period of time the EPA had conditionally approved the PRPs request to discontinue pumping and treating groundwater based on declining TCE concentrations.

The average annual O&M costs from September 1997 through September 1999 are shown in Table 2 and include the costs of groundwater recovery, treatment, monitoring and reporting. The O&M costs from October 1999 through July 2003 are attributable to monitoring and reporting activities only. The O&M costs for the last five years are also included in Table 2, below, and include groundwater recovery, treatment, monitoring and reporting since the treatment system was restarted in 2003. The reported costs for the groundwater recovery, treatment, sampling and monitoring are consistent with the cost estimate for the remedy provided in the ROD of $57,000 to $148,000 per year. As can be seen from Table 2, the annual costs associated with, monitoring and reporting, alone, are substantially lower.

Table^2 - Annual System Operations/O&M Costs:

Dates

From

9/1997

10/1999

10/2003

To

9/1999

7/03

3/2008

Total Annual Cost rounded to nearest $1,000

$128,000

$42,000

$134,380

V. Progress Since the Last Five-Year Review

The first Five-Year Review for the Site was signed in September 2003. At that time the PRPs or Respondents were in the process of modifying the collection system so that water would be recovered from two recovery wells instead of one. Groundwater recovery operations and treatment of the groundwater started in November 2003, following completion of the recovery system modifications. The treatment of groundwater has been taking place since the second start up and continues with quarterly groundwater and treatment system effluent monitoring taking place. The results of the monitoring are discussed further in the data review section below.

On September 3, 2003, the USEPA, DNREC and representatives of the PRPs conducted a Site inspection for the first five-year review. The following recommendations and follow-up actions were taken as a result of that inspection:

10

Actions Taken Since Last Five-Year Review

Issues from Previous Review

Unsecured monitoring wells.

Unauthorized destruction of monitoring wells

The current health-based standard (Region 3 risk-based concentration or RBC ) for manganese in drinking water Is 780 ug/L. The 3,000 ug/L standard that was determined to be protective at the time the ROD was issued is no longer considered to be protective.

Compliance with surface water discharge standards for metals has not been verified

Contents of two 55-gallon drums on the Chem-Solv, Inc. property have not been established.

Recommendations/ Follow-Up Actions

Install bolts or locks on wells to prevent tampering. Reassess monitoring well network, develop a plan for abandoning unnecessary wells, and replace destroyed wells integral to the groundwater monitoring program. Install posts around

selected monitoring wells to prevent damage.

Issue an ESD in order to establish a protective cleanup standard for manganese in ground water.

Determine if treatment to remove metals from recovered ground water is necessary to meet discharge standards. Assess contents of drums and dispose appropriately.

Party Responsible

PRP

PRP

EPA

EPA

•

PRP

Action Taken and Outcome

RPs secured all site wells with either a bolt or lock as appropriate.

The destruction of several groundwater monitoring wells was inadvertent and the result of site improvement activities. Since the observation of the loss of several wells, a groundwater monitoring well network inventory was developed for the site by EPA and the PRPs. Existing groundwater monitoring wells which might be considered obscure were more clearly delineated. Those ground water monitoring wells identified as being at hjgh risk of damage were protected by metal-shrouded cement bollards. A review of the annual groundwater quality data for manganese Indicates that manganese exceeded the ARAR for the Site on only one occasion. However, that sample was a non filtered groundwater sample analyzed as part of the quarterly monitoring. In addition, the presence of dissolved manganese in groundwater Is believed to be the result of the utilization of the naturally occurring manganese (III) and manganese (IV) in the aquifer formation as an electron acceptor during anaerobic biodegradation of organic carbon. Further evaluation will be conducted over the next 5 years. Review of effluent samples demonstrated compliance with discharge limits.

An inspection of the contents of the two 55-gallon drums staged on site was made and the drum(s) and their contents disposed of in accordance with all applicable regulations.

Date(s) of Action

8/2008

8/2008

8/2008

8/2008

6/2004

11

VI. Five-Year Review Process

Administrative Components

The Respondents and DNREC were notified of the initiation of the five-year review in June 2008. The Chem-Solv, Inc. Five-Year Review team was led by Christian Matta of EPA, Remedial Project Manager (RPM) for the Site, and included members from the Regional Technical Advisory staff with expertise in hydrogeology, air pathway analysis, risk assessment and statistics. State Project Manager Robert Asreen assisted in the review as the representative for the support agency. Douglas Beaver of Rare Earth Envirosciences, Inc. acted on behalf of the PRPs to provide information and address issues relating to the Site.

^ EPA began the five-year review for the Site in March of 2008. The components of the five-year review include:

community involvement; document review; data review; Site inspection; and Five-Year Review Report development and review.

Community Involvement

An advertisement appeared on May 26, 2008 in the Delaware State News. The advertisement explained the five-year review process, provided point of contact information, and identified the location of the information repositories for the Site. No comments were received from the community as a result of the advertisement.

Another notice will be sent to the same newspaper to announce that^the Five-Year Review Report for the Chem-Solv, Inc. site has been completed. Information on the results of the review and the report availability will be part of the announcement.

Document Review

This five-year review consisted of a review of relevant documents including semi-annual residential well test results, quarterly groundwater monitoring data, and monthly effluent monitoring reports (See Attachment 3). The groundwater cleanup standards and Delaware Water Quality Standard listed in the 1992 Record of Decision were also reviewed (See Attachment 4).

Data Review

Groundwater Recovery and Treatment Monitoring

In general, groundwater contaminants were detected at their highest levels early in the remediation history of the Site (1985 through 1988). During this period, soil and groundwater

12

cleanup activities implemented by the State eliminated a significant mass of source material and resulted in a 250-fold reduction in groundwater contaminant concentrations. Following the implementation in 1997 of the remedy selected by EPA, further reductions in the TCE concentrations in the groundwater were observed, leading to EPA's approval of the conditional termination of groundwater collection and treatment in 1999.

On March 4, 2003, EPA determined that TCE concentrations had not declined and based on results of monitoring well samples collected since the treatment system was shut off; determined that TCE concentrations were exhibiting a statistically significant increasing trend in two Site monitonng wells. As a result the Respondents modified the groundwater recovery system and subsequent treatment by aeration commenced in November 2003.

Groundwater is, and has been, withdrawn from the basal portion of the Columbia Formation at a rate of approximately 60 gallons per minute, on average, since November 2003. The resultant total ground water recovered and treated by aeration for discharge to surface water is 202,336,318 gallons (November 1997 through June 2008).

In order to confirm that the quality of the treated effluent was within acceptable limits, samples of both the raw influent and treated effluent were collected on a weekly basis for the first two months of system operation and then monthly. Data obtained through laboratory analyses of the treated effluent samples indicate that the treated effluent has never contained a Site related contaminant of concern at levels exceeding site-specific cleanup standard or Maximum Contaminant Level ("MCL"). Moreover, no site-specific volatile organic chemical of concern has ever been detected in the treated effluent above the laboratory analytical method detection limit.

Monitoring of the air stripper's emissions are conducted on a quarterly basis in accordance with' DNREC's authorization to discharge. Volatile'organic compounds have never been detected in the waste stream.

These data demonstrate that this method of groundwater treatment has been and is successful in meeting regulatory-mandated discharge limitations and is protective of human health and the environment.

Laboratory analytical data of samples of the raw influent to the treatment system similarly collected yield estimations of the cumulative mass removed from ground water (in grams) of the site-specific volatile organic chemicals of concern. These data are summarized below:

Volatile Organic Compound

Mass Removed (grams)

1,1,1-TCA

41.77

TCE

3073.74

Xylenes

27.57

Toluene

12.14

1,2-DCA

193.90

' 1 Benzene

3356.69

13

Private Well Test Results

Potable supply well sampling and laboratory analysis of both residential and commercial properties is conducted on a semi-annual basis. Specifically, potable supply wells identified as Green Seasons, Williams, Harris, American Roofing, Durham, Curley, Killen, Lynch, George and White are sampled and analyzed for volatile organic compounds. (Attachment 1 -Potable Supply Well Location Map)

No site-specific volatile organic chemical of concern has been detected in any of these potable supply wells in any semi-annual sampling event. However, sampling should be conducted to confirm that manganese concentrations in these wells remain at acceptable levels.

Groundwater Monitoring

Groundwater monitoring has been conducted at the Site since the mid 1980s. Since the recovery of contaminated groundwater was discontinued in October 1999, concentrations of six'' of the nine contaminants for which groundwater cleanup levels were established at the Site have remained below their respective cleanup levels. Levels of TCE and benzene have not been found to be exceeding the cleanup levels (5 lug/L, and 5Aig/L, respectively) established in the ROD (see Tables 3a, 3b ) since January of 2008. As of February 2008, manganese concentrations are also below the revised cleanup level which is EPA Region 3's current risk-based concentration(RBC) of 780 ug/L for residential tap water (see Table 3c).

In accordance with the ROD, ground water sampling and laboratory analysis of select groundwater monitoring wells is conducted on a quarterly basis. Specifically, ground water monitoring wells 8B, 9B, 45B, MW-l-2-40, MW-96-1-55, MW-96-3-45, MW-96-4-45, MW-97-7-48, MW-97-8-48, MW-97-9-47 and MW-97-10-45 (Attachment 1 - Site Location Map) are sampled and analyzed for volatile organic compounds.

During the five years since resuming groundwater recovery and treatment, four of the eight volatile organic contaminants of concern for which cleanup levels were established at the site have not been detected in groundwater at levels above the analytical method detection limit (MDL). Those contaminants are acetone, 1,2-dichloroethane, tetrachlorethene, and 1,1,1-trichloroethane.

Two other volatile organic chemicals of concern for which cleanup levels were established at the Site, toluene and xylene, have been detected below their respective MCLs and at concentrations only slightly above their respective analytical MDL. The low detections of these compounds were temporally sporadic and spatially limited so as to have no environmental significance.

''Concentrations of acetone, 1,2-dichloroethane, tetrachloroethene, toluene, 1,1,1-trichloroethane and xylene have remained below cleanup levels since at least 1998.

14

Only two chemicals of concern, TCE and benzene, were detected a levels that exceed the Site specific cleanup level, or MCL of 5 pg/l during the quarterly groundwater sampling events that have taken place since November 2003. ' r

TCE has been detected in ten of the eleven ground water monitoring wells sampled, of which only three wells (9B, 45B, and 8B Attachment A - Site Location Map, have had concentrations exceeding the MCL, 5 pg/l (See Table 3a). Graphs of concentration over time in these wells are set forth at Attachment 2.

It is important to note that just prior to November 2003 the wells with concentrations of TCE exceeding the MCL were the two wells physically located on the Chem-Solv, Inc. Site, 9B and 45B, and the groundwater monitoring well 8B, which is located nearest these wells in a hydraulically downgradient direction. ,

Since resuming treatment of groundwater in November 2003, only groundwater monitoring well 9B, located on the Chem-Solv, Inc. Site, has exceeded the MCL for TCE.

TCE has also not been detected hydraulically downgradient of the recovery well network above its MCL and TCE has never been detected in the downgradient monitoring well locations above the MDL since January 2006.

During the period 2003-2008, benzene has been detected in five of the eleven ground water monitoring wells sampled. However, since resuming groundwater treatment operations in November 2003 using the modified recovery well network, three of the wells, MW-96-3-45, MW-96-4-45 and MW-97-8-48 (Attachment 1 - Site Location Map), have contained benzene at concentrations at or above^the MDL or at concentrations exceeding the MCL for benzene of 5 pg/l (See Table 3b below). Graphs of concentration over time in these wells are set forth at Attachment 2.

Since resuming treatment of groundwater at the Site, benzene has been detected in two groundwater monitoring wells, MW-96-3-45 and MW-97-8-48, at levels exceeding the MCL. MW-96-3-45 is located hydraulically upgradient of the recovery well network and MW-97-8-48 is located hydraulically downgradient of the recovery well network. Benzene has been detected in MW-97-8-48 on four occasions (October 2003, July and September 2005 and January 2006). During two of those occasions, July and September 2005, benzene was found in excess of the MCL.

Review of the data indicates that benzene has never been detected in well 9B or 45B, which monitor the groundwater directly below the Chem-Slov, Inc. Site or in monitoring well 8B which is immediately downgradient of the Site. Review of the data also indicates that benzene has never been detected in groundwater within the basal portion of the Columbia Formation aquifer beneath the Chem-Solv, Inc property since the sampling and analysis of groundwater has been taking place at the Site. As a result the data suggests a source of benzene unrelated to the Chem-Solv Inc. Site or facility and warrants further review over the course of the next five years.

15

Review of the data provides sufficient information to demonstrate that the selected remedy has and continues to be effective. The remedy as implemented is protective of human health and the environment. The effectiveness of the remedy is demonstrated by 1)benzene and TCE have not been detected at levels exceeding their respective MCLs since January 2008, 2) for five of the ten last quarterly sampling events benzene and TCE have been within their respective cleanup goals and 3) groundwater concentrations for all volatile organic chemicals of concern were within the respective Site-specific cleanup goals during the most recent quarterly groundwater monitoring event, April 2008.

16

Table 3a - Quarterly Trichloroethene (TCE) Concentrations (jug/L) in Groundwater

WellfD

9B

45B

MW96-I-55 .

8B

MW96-3-45

MW97-10^5

MW96-5-48

MW96-6-48

MW96^-45

MW97-7-48

MW97-9-47

MW-I-2-40"

MW97-8^8

Oct. 03

1.9

7.1

ND

18.0

0.9

ND

UAV

UAV

2.5

0.5

ND

0.4

2.4

Jan. 04

1.5

2.0

mj

3.6

0.6

ND

UAV

UAV

4.1

2.1

0.6

ND

0.7

Apr. 04

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

Jul. 04

1.6

0.9

ND

3.3

0.5

ND

UAV

UAV

1.0

,2.0

ND

0.6

ND

Oct. 04

2.0

0.6

ND

2.0

0.4

ND

UAV

UAV

0.8

10

ND

0.4

ND

Jan. 05

1.0

ND

ND

2.0

0.7

ND

UAV

UAV

2.0

0.5

ND

ND

ND

Apr. 05

12.0

0.4

ND

0.7

2.0

ND

UAV

UAV

3.0

ND

ND

0.7

ND

Jul. 05

5.0

0.8

ND

0.7

1.0

ND

UAV

UAV

1.0

0.6

ND .

2.0

?vro

Sep. 05

27.0

2.0

ND

0.5

1.0

ND

UAV

UAV

1.0

1.0

ND

0.9

ND

Jan. 06

4.0

ND

ND

3.0

1.0

ND

UAV

UAV

4.0

0.7

ND

ND

ND

Apr. 06

6.0

ND

ND

2.0

1.0

ND

UAV

UAV

3.0

0.8

ND

ND

ND

Jul. 06

2.0

ND

ND

1.0

0.6

ND

UAV

,UAV

2.0

0.7

ND

ND

ND

Oct. 06

4.0

ND

ND

2.0

ND

ND

UAV

UAV

0.8

0.5

ND

ND

ND

Jan. 07

2.0

ND

ND

-0.8

0.4

ND

UAV

UAV

0.7

0.5

ND

ND

ND

Apr. 07

5.0

ND

ND

0.7

0.6

ND

UAV

UAV

0.7

ND

ND

ND

ND

Jul. 07

6.0

ND

ND

2.0

0.6

ND

UAV

UAV

3.0

0.4

ND

ND

ND

Oct. 07

7.0

0.4

ND

ND

0.9

ND

UAV

UAV

2.0

ND

ND

ND

ND

Jan. 08

40

ND

ND

ND

ND

ND

UAV

UAV

1.0

ND

ND

ND

ND

Apr. 08

5.0

ND

ND

ND

2.0

ND

UAV

UAV

1.0

ND

ND

ND

ND

Note: Values given in bold text exceed 5 jug/L cleanup standard. ND - means analyte not detected. UAV ~ means sample not collected or not analyzed.

Table 3b - Quarterly. Benzene Concentrations {fj.glL) In Groundwater

- . Well ID

9BB

45B

MW96-1-55

83

MW96-3-45

MW97-10-45

MW96-5-48

MW96-6-48

MW96-4-45

MW97-7-48

MW97-9-47

MW-l-2-40

MW97-8-48

Oct. 03 :

ND

ND

ND

ND

36.0

ND

UAV

UAV

ND

0.5

0.8

ND

1.1

Jan. 04

ND

ND

ND

ND

8.5

ND

UAV

UAV

27.0

ND

ND

ND

ND

Apr. 04

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

UAV

Jul. 04

ND

ND

ND

ND

14.0

ND

UAV

UAV

1.8

ND

ND

ND

ND

Oct. 04

ND

ND

ND

ND

8.0

ND

UAV

UAV

1.0

ND

ND

ND

ND

Jan. 05

ND

ND

ND

ND

4.0

ND

UAV

UAV

3.0

ND

ND

ND

ND

Apr. 05

ND

ND

ND

ND

1.0

ND

UAV

UAV

2.0

ND

ND

ND

ND

Jul. 05

ND

ND

ND

ND

ND

ND

UAV

UAV r. •

4.0

ND

ND

ND

9.0

Sep. 05

ND

ND

ND

ND

ND

ND

UAV

UAV

4.0

ND

ND

ND

38.0

Jan. 06

ND

ND

ND

ND

2.0

ND

UAV

UAV

4.0

ND

ND

ND

4.0

Apr. 06

ND

ND

ND

ND

9.0

ND

UAV

UAV

1.0

ND

ND

ND

ND

Jul. 06

ND

ND

ND

ND

6.0

ND

UAV

UAV

ND

ND

ND

ND

ND

Oct. 06

ND

ND

ND

ND

ND

ND

UAV

UAV

ND

ND

ND

ND

ND

Jan. 07

ND

ND

ND

ND

ND

ND'

UAV

UAV

ND

ND

ND

ND

ND

1

Apr. 07

ND

ND

ND

ND

4.0

ND

UAV

UAV

ND

ND

ND

ND

ND

1

Jul. 07

ND

ND

ND

ND

9.0

ND

UAV-

UAV

ND

ND

ND

ND

ND

Oct. 07

ND

ND

ND

ND

19

ND

UAV

UAV

ND

, ND

ND

ND

ND

Jan. 08

ND

ND

ND

ND

7.0

ND

UAV

UAV

ND

ND

ND

ND

ND

Apr. 08

ND

ND

ND

ND

3.0

ND

UAV

UAV

ND

ND

ND

ND

ND

oo

Note: Values given in bold text exceed 5 //g/L cleanup standard. ND means analyte not detected. UAV ~ means sample not collected or not analyzed.

Table 3c - Manganese Concentrations (iu.glL) in Shallow Groundwater

Well ID

34AR

CPW-1S

Feb.03

543

67.2

Feb. 04

97.8

422

Feb. 05

76.4

2330

Feb. 06

402

95.5

Feb.07

55

10

Feb. 08

67.8

37.1

Note: Concentrations in Bold exceed Region III RBC of 780 ug/L

Site Inspection '

An inspection at the Site was conducted on July 1, 2008 by the RPM, State Project Manager and PRP representative. The purpose of the inspection was to assess the protectiveness of the remedy by ensuring actions were taken to address issues identified in the 2003 Five-Year Review, reviewing the local land use patterns and evaluating the integrity of Groundwater monitoring and recovery wells, and Groundwater treatment and discharge facilities.

No significant issues were identified regarding the Groundwater recovery, treatment and discharge facilities. However, Site monitoring wells were not adequately secured. This continues to be a problem at this Site which will require inspection of the monitoring wells during each sampling event. Simple steps (e.g., locking or bolting well caps, installing posts to prevent structural damage to wells) are recommended in order to ensure the security and integrity of the Site monitoring wells. Following each sampling event, all monitoring wells should be checked and appropriate measures taken to secure wells.

The groundwater pump and treat system and the groundwater recovery wells were observed. The system remains in the original location. However, due to modifications in 2003, the recovery well locations have been changed.

During the Site inspection several monitoring wells were inaccessible due to the property owner/occupant or other party covering the wells with gravel/dirt or parking vehicles over the wells. Steps need to be taken to prevent this from happening in the future and to prevent further ~ destruction/loss of monitoring wells which may occur if wells-'are damaged by vehicular traffic or lost due to burial.

In addition, one rusting drums was,observed immediately adjacent to the former Chem-Solv, Inc office building. The drum was partially crushed, missing the cap and had been pierced on the side. The contents, if any, of the drum have not been determined.

Some land use changes have occurred in the vicinity of the Site during the past several years, including the construction of a cement company in the new business park south of the Chem-Solv, Inc. property and changes in the businesses utilizing adjacent properties.

19

EPA will conduct a follow-up Site visit to confirm the security of Site monitoring wells and observe general Site conditions over the next five years.

Interviews

No specific interviews were conducted as part of the 2003 Five-Year Review. However, for this five-year review residents and/or local business owners were contacted via telephone in order to evaluate the need for one on one interviews between EPA, the State and residents or property owners surrounding the Site.

Very little activity has taken place at the Site and all residential wells have been replaced by deeper new wells. Those residents and local business persons contacted reported that they did not feel the need for one on one interviews. However, telephone interviews were conducted with affected resident and one affected business/property owner. Both interviewees indicated that they did not have any concerns with the Site or what was taking place and that they felt well informed. They noted that the PRP representative who collects groundwater samples from their wells during various time throughout the year conveyed information to them and took the time to answer any questions that they might have.

VII. Technical Assessment

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

EPA's review of documents, ARARs and risk assumptions, as well as the results of the Site inspection, indicate that the remedy is functioning as intended by the ROD. The extent of the groundwater plume has been well defined and progress is being made, through the capture of contaminated groundwater, toward achieving the remedial objective to restore groundwater to its beneficial use as a potential drinking water source. VOC concentrations in treated Groundwater discharged to surface water from 2003 to 2008 met the Delaware Water Quality Standards for protection of human health and aquatic life; however, metals concentrations in the air stripper influent and effluent were not determined. Effective groundwater monitoring and implementation of the GWMZ, together with the replacement of shallow water supply wells with deeper wells, have prevented exposure to contaminated groundwater.

O&M annual costs are consistent with original estimates and there are no indications of any difficulties with the remedy.

The PRPs have recommended, and are in the process of completing, modifications of the groundwater recovery well network in order to optimize the efficiency of the removal of TCE from the groundwater. The nionitoring well network, when properly maintained, provides sufficient data to assess progress toward the attainment of the groundwater cleanup standards. No additional opportunities for system optimization were observed during this review.

'• The institutional controls that are in place include State implementation of a GWMZ in order to prevent the installation of water supply wells within the contaminated portion of the Columbia

20

aquifer and in order to ensure that any well installed in the underlying Kirkwood Formation is double cased. No violations of these groundwater use restrictions and well construction requirements were observed.

A vapor intrusion assessment was conducted in 2003, as a component of the first Five-Year Review for this site; potential risks were determined to be unremarkable. Since 2003, the manner in which this pathway is evaluated has changed significantly but the conclusion of no risk due to vapor intrusion remains unchanged. New information or changes in the evaluation process will be considered in the next five year review.

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

Changes in Exposure Pathways or Assumptions:

The baseline human health risk assessment conducted during the RI evaluated the risks associated with residential exposure to contaminated groundwater and identified unacceptable carcinogenic and nbncarcinogenic risks for this exposure pathway.

In addition, during 2003 Five-Year Review, EPA performed a screening level assessment of the risks associated with exposure to TCE, assuming that TCE present in groundwater is migrating into indoor air. The calculated excess lifetime cancer risk for this exposure scenario was 2.6 X 10" ^ and falls within EPA's acceptable risk range of 1 X 10" to 1 X lO""*. Based on the evaluation of this additional exposure pathway, no changes in the RAOs given in Section IV of this report are required. DNREC is performing a Brownfield Site Investigation as part of the State redevelopment initiative. Sampling on the former Chem-Solve Inc. property has been done in order to assess site soils and the vapor intrusion pathway. The findings will be presented in a final report due to be finalized by October 2008. This report should be reviewed for potential changes to the screening assessment. As of the date of this report there is no risk expected due to vapor intrusion at this Site.

Some land use changes have occurred in the vicinity of the Site during the past several years, including the construction of a cement company in the new business park south of the Chem-Solv; Inc. property. Although groundwater flow patterns do not appear to have been significantly affected by this development, hydraulic gradients should continue to be monitored and evaluated in order to maintain an accurate understanding of potential contaminant migration pathways.

Changes in Toxicity Data and Cleanup Standards:

The cleanup levels listed in the ROD are still protective with the following exceptions:

For manganese, the Region 3 risk-based concentration (RBC) for residential tap water is currently 780 ug/L. This implies that the cleanup standard of 3,000 ug/L (No Observed Adverse Effect Level) given in the ROD would not be protective under residential exposure conditions.

21

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

No other information has come to light that calls into question the protectiveness of the remedy as constructed in conformance with the ROD.

Technical Assessment Summary

According to the data and documents reviewed and the Site inspection, the remedy is functioning as intended by the ROD, although compliance with.surface water discharge standards could not be fully evaluated due to the absence of effluent monitoring data for inorganics. There have been no changes in the physical conditions of the Site that would affect the protectiveness of the remedy. On the other hand, there have been changes in the toxicity factors for one of the contaminants of concern identified in the ROD: manganese. EPA will assess the need for an additional ESD during the next five-years. If appropriate, and ESD will be implemented in order to revise the cleanup standard for manganese. Institutional controls required by the ROD, as modified by the ESD, are in place and remain in effect. There is no other information that calls into question the protectiveness of the remedy.

/

22

VIM. Issues

Table 4 - Issues

Issue

Unsecured monitoring wells

Restricted access to monitoring wells

New toxicity value for manganese

Unverified compliance with surface water discharge standards for inorganics ^

Drum with unidentified contents on-site.

Currently Affects Protectiveness

(Y/N)

f

N

N

N

N

N

Affects Future Protectiveness

(Y/N)

N

N

Y

Y

Y

IX. Recommendations and Follow-Up Actions

Table 5 - Recommendations and Follow-Up Actions

Issue

Unsecured monitoring wells

Restricted access to monitoring wells

(

Recommendations/ Follow-up Actions

Install bolts or locks on wells to prevent tampering.

Reassess monitoring well network and develop a plan for abandoning unnecessary wells and replacing those wells which are integral to the groundwater monitoring program but were destroyed. Install posts around selected monitoring wells to prevent damage.

Party Responsible

PRP

PRP

Oversight Agency

EPA/State

EPA/State .

Milestone Date

12/30/08

12/30/08

Affects Protectiveness?

(Y/N)

Current

. N

N 5

Future

N

N

23

Issue

New toxicity value for manganese

Unverified compliance with surface water discharge standards for inorganics

Drum with unidentified contents on-site.

Recommendations/ Follow-up Actions

Assess the need for and if appropriate issue an ESD to establish a protective cleanup standard for manganese in groundwater. EPA will continue to monitor the groundwater over the next five years to determine if an ESD is needed to establish a site specific cleanup level for manganese. The ESD will also identify any .changes that need to be made to the sampling plan as well as treatment system to ensure magnesium is treated and will establish the inorganic surface water discharge standards for treated groundwater.

Determine if treatment to remove metals from recovered groundwater is necessary in order to meet discharge standards.

Determine if drum contains hazardous materials and select waste management option.

Party Responsible

EPA

PRP

PRP

Oversight Agency

EPA/State

1

EPA/State

EPA/State

Milestone Date

9/30/10.

9/30/2009

6/30/2009

Affects Protectiveness?

(Y/N)

Current

N

•

N

N

Future

Y

)

Y

Y

24

Issue

Vapor Intrusion

Need to confirm manganese not found in all wells

Groundwater monitoring data indicative of source area unrelated to Chem-Solv facility.

Recommendations/ Follow-up Actions

Review of the findings of the Supplemental Brownfield Investigation vapor intrusion report being developed as part of a state redevelopment initiative.

All wells monitored as partof this remedy should have samples analyzed to identify the manganese levels.

Review information and assess potential for a source area not related to Chem-Solv facility.

Party Responsible

EPA

PRP

EPA

Oversight Agency

EPA/State

EPA/State

EPA/State

Milestone Date

6/30/2009 .

9/30/2009

9/1/2013

Affects Protectiveness?

(Y/N)

Current

N

N

N

Future

Y

Y

Y

1

X. Protectiveness Statement

The remedy currently protects human health and the environment because exposure pathways that could result in unacceptable risks are being controlled and institutional controls are preventing exposure contaminated groundwater.

In order for the remedy to be protective in the long term, EPA will determine if an ESD should be issued to establish a cleanup standard for manganese which is protective of human health. In addition, a determination will be made regarding the need to provide additional treatment to remove metals from recovered groundwater in order to meet standards for discharge to surface water. Finally, the material in the on-site drum will be analyzed to determine the appropriate waste management option.

A vapor intrusion assessment was conducted in 2003, as a component of the first Five-Year Review for this Site; potential risks were determined to be unremarkable. Since 2003, the manner in which this pathway is evaluated has changed significantly but the conclusion reached for this Site remains unchanged. There is currently no risk due to vapor intrusion. DNREC is performing a Brownfield Site Investigation as part of the State redevelopment initiative. The findings will be presented in a final report due to be finalized by October 2008 and will be reviewed for potential

25

changes to the screening assessment. As of the date of this report there is no risk expected due to vapor intrusion at this Site.

XI. Next Review

Since site conditions do not allow for unlimited use and unrestricted exposure, EPA will need to conduct another five year review of the Chem-Solv, Inc. Superfund site by September 2013, five years from the date of this review:

26

ATTACHMENTS

ATTACHMENT 1 Maps

N k Scale (feet)

0 75 150

CHEM-SOLV, INC. SUPERFUND SITE Cheswold, Kent County, Delaware

e Project No. CSI91001

FIGURE 2 5 Year Review Summary - August 2006

POTABLE SUPPLY WELL . LOCATION MAP

ATTACHMENT 2 Monitoring Well Contaminant Concentration Graphs

Chem-Solv, Inc. Superfund Site: Monitoring Well 9B Chemical of Concern Concentration vs. Time

30.0

25.0

20.0

c o ^ 15.0

c s c o o

10.0

5.0 -

0.0

—•—TOE —A— Benzene

MCL

Oct-03 Apr-04 Oct-04 Apr-05 Oct-05 Apr-06 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08

Sampling Date

Chem-Solv, Inc. Superfund Site: Monitoring Well 45B Chemical of Concern Concentration vs. Time

8.0

0.0

h ^ - * ft * * * ft—--^ ft ft

—•—TCE —ft— Benzene

MCL

Oct-03 Apr-04 Oct-04 Apr-05 Oct-05 Apr-06 Oct-06 Apr-07 Oct-07 Apr-08 Oct-0.8

Sampling Date

Chem-Solv, Inc. Superfund Site: Monitoring WeU 8B Chemical of Concern Concentration vs. Time

20.0

18.0

16.0

14.0

B 3

C O

'8 ^ C tt o c 0

u

12.0

10.0

80

6.0

4.0

2.0

0.0

- •—TCE -ft— Benzene

MCL

Oct-03 Apr-04 Oct-04 Apr-05 Oct-05 Apr-06 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08

Sampling Date

Chem-Solv, Inc. Superfund Site: Monitoring Well 96-3-45 Chemical of Concern Concentration vs. Time

40.0

—^—TCE —ft— Benzene

MCL

Oct-03 Apr-04 Oct-04 Apr-05 Oct-05 Apr-06 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08

Sampling Date

Chem-Solv, Inc. Superfund Site: Monitoring Well 96-4-45 Chemical of Concern Concentration vs. Time

30.0

—•—TCE —ft— Benzene

MCL

Oct-03 Apr-04 Oct-04 Apr-05 Oct-05 Apr-06 Oct-06

Sampling Date

Apr-07 Oct-07 Apr-08 Oct-08

Chem-Solv, Inc. Superfund Site: Monitoring Well 97-8-48 Chemical of Concern Concentration vs. Time

40.0

—•—TCE —ft— Benzene

MCL

Oct-03 Apr-04 Oct-04 Apr-05 Oct-05 Apr-06 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08

Sampling Date

ATTACHMENTS

List of Documents Reviewed

Remedial Investigation Report, Chem-Solv, Inc. Site, November 1991

Record of Decision for the Chem-Solv, Inc. Site, March 1992

Administrative Order for Implementation of Response Activities at the Chem-Solv,' Inc. Superfund Site, Docket No. III-93-11-DC, December 29, 1992

Work Plan for Remedial Design Services at the Chem-Solv Site, August 26, 1993

Operations & Maintenance Manual for Interim Remedial Action Groundwater Treatment System, Chem-Solv Superfund Site, December 1997

Preliminary Close Out Report, Chem-Solv, \nQ.. Superfund Site, June 30, 1998

Explanation of Significant Differences, Chem-Solv, Inc. Superfund Site, June 18, 1999

Quarterly Groundwater Monitoring Reports, May 1994 through July 2003

Semi-Annual Well Testing Results, 1996 through April 2003

Quarterly Effluent Monitoring Reports, September 1997 through October 1999

Quarterly Groundwater Monitoring Reports, July 2003 through April 2008

Semi-Annual Well Testing Results, April 2003 through February 2008

Quarterly Effluent monitoring Reports, January 2004 through April 2008'

Remedial Action Implementation Summary: 2003 - 2008 Chem-Solv, Inc. Superfund Site, Cheswold, Kent County, Delavvare

ATTACHMENT 4

Applicable or Relevant and Appropriate Requirements (ARARs)

TABLE 11

APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS) AND TO BE CONSIDERED MATERIAL (TBCs)

CHEM-SOLV, INC. SITE

ARARorTBC ""

LCSIEMiCALSPEaFIC

Legal Citadan aanificadon

A. Water

1. Safe Drinking Water Act

a. Marimum Contaminant l£veb(MCU)

42U.S.C§300fets^ .

40 CPJUI 141.11-12

b. Maximum Contaminant Level

Xsfioals (MCLGs)

3 0 CD CD • O CTi cr> CO

Relevant and Appropriate

Requirement Synopsis

40 C F J l i 14130-51

2. EPA Health Advisories

Relevant and Appropiiate

Enforoeable standaids for pubUc drinking vrater supply systems (with at least fifteen servloe connectioas of used by at least 25 peruns). MCLs apply to public water systems diat provide piped water fior human oonsumption. These requirements are not directly applicable since groundwater at the site is used as a private drinking water supply. MCLs are; under the dicumstaaces of this sii^ relevant and appropriate requimnents.

Applicability to Selected Ranedy

£PAOfBceof Drinking Water

To be Considered

Non-enforceable health goab for public water supplies. The NCP requires diat MCLGs shall be attained by remedial actions for ground water that is a current or potential louroe of drinking %vater, where du MCLGs are relevant and approptiate under the dmimsianoes <^ the release. Analogous to ilie discusskm ibr MCLs, MCLGs are relevant and appropriate requiremaits.

Remedial action must meet MCLs for oontaminaaa of concern for which they exist and for which the MCLG is set at a level of zero. The NCP requires that where the MCLG for a contaminant has been set at a level of zero, the MCL promulgated for that contaminant shall be attained by remedial actions for ground water that is a cunent or potential source of drinking water, where the MCL b relevant and appropriate trnder ttie dmimnances (tf tbe release.

Remedial action must meet non-zero MCLGs for contaminants of oonoera for which diey exist

Non-enforoeable guklelines for public water supply systems

To be considered for remedial actions involving groundwater monitoring, recoveiy and treatment.

ARARorTBC

3. Hcaltli Effects Assessment

\

4. State of Delaware Reguladons Goweniing PubUc Drinking Water, Revised May 19.1989

5. Ddaware Surface Water Quality Standard of Feb. 1990

B.Air

OeanAirAct

l.NadonalAmUentAIr Quality Standards

2. Naoonal Emissions Standardsfbr Hazardous Air Pcdlutants

l£gal Citation

Tide 16 § 122

J

§S9.3(a)(0 afld9.3(b)(0

42 U 5 £ 57401

40CFJa.Pait50

40CFJll>art61

Oassificadon

To be Considered

Relevantsnd Appropriate

AppikaUe

Rdevantand Appropriate

Relevantand Appropiiate

Requirement Synopsis

Non-enforoeabie toxicity data for specific chemicals for use in public healdi assenmena. Abo to be considered are Carcinogenic Potency Facton and Refarenoe Doses provided in die Supetfiind Public Healdi Evaluadon Manual.

Sets criteria for public

lequirementi are not direcdy apfdicable since groundwater at the site b used as a private drinking water s u p ^ . However, under the dicufflstanoes of thb site, diese requirements are relevant and appropriate.

Qiterla are provided to maintain

reocatioaal puiposes; the propagation iind pXMBCticn Of fish «nH flqiiarff liCt

and Other bftiWM"! uses of water.

Natkxial Hni<t»rif»i« oo ambient oonoentiadons of pollutants bitended to protect public beakfa and wdCare. Applies to for potential releases reiuliing (too groundwater treatment.

Standards promulgated for air embsions bom specific source categories. Not appUcable but may be relevant and aniropiiate for cmbdons bom air stiippen at Superfund sites.

Applicability to Selected Remedy

To be considered where remedial alternatives address lisk-based criteria or standard setting for cleanup.

which are more stringent then Federal MCU and non-zero MCLGs

Any sutfooe water dischaige must 1 meet diese leveb if more stringent H dian federal regulations.

Relevant and appropriate shouU

stripper.

Air emissions from die air stripper must meet dw standard for benzene |

C5

CD

en p

ARARorTBC |

nuxxnoHSPBanc

A. The Endangered SpedesActofl978

B. The Archaecdogical and Historical Preservation Act of 1974

Act of 1973

D. Procedures for Implementing the Requirements of the Council on Environmental Quality on the National Environ­mental Policy Act

E. Ground Water H Protection U Strategy of 1984

1 F. National Historic U Preservation Act of

1 - 1 ^ O

" CD -

Legal Citation |

16U.S.C§1S31 I SO CFA Part 402

16U5.C§469

Tide 7, Delaware Code, (3i 66, §6607

1 40CJ'.RPait6 Appendix A

EPA44a^6«M)02

16 U.S.C. §§470 et sea- "" 36 C F J t Pan 800

Classification |

AppUcable >

Applicable

Applicable

To be Considei«d

Requiremoit Synopsis |

Requires federal agencies to easure that any action authorized by an agency b not likely to jeopardize the continued existence of any endangered 1 or threatened species or advenely affect its critical habitat

Requirements relating to potential loss or destruction of significant scientific, hbtoikal, or archaeokigical data

Revised June 29,1984- Requires activities diat may advenely affect wedands hi Delaware to be pennitted. Permits must be approved by die county n: munidpality having Jurisdiction.

EPA's policy for carrying out die provisions of Executive Order 11990 (Piotemon of Wedands). No activity diat advetsdy aCEects a wedand shall be permitted if a practicable alternative that has less effect b available. Ifdierebnoodier practical alteniative; hnpacts must be mitigated.

Identifies ground water quality to be achieved during remedial actions

' based on aquifer characterbtics and 1 use.

Requhes remedial action to take into account effects on propetties included in or eligible for die National Regbter of Hbtoric Places and to minimize hann to National Hbtotic Landmarks.

Applicability to Selected Remedy

Potentially aCTected endangered species have not been identified. The

resources should any be identified in thefiinire. |

Archaeological and hbtorical rescHiroes will be identified and actions taken to mitigate any adverse effects on diose resources diat wouM result from implementation of die remedial action (e.g., construction of an onsite trBannent system). |

Applies shouU discharge to surface water affect wetlands.

Applicable shouU remediation involve discharge to surface water.

Ilie EPA aquifer classification vrill be taken into consideration during design and implementation of die treatment remedy.

If die property b eligible for or included on the National Regbter of Hbtoric Places, actions will be lakpn to mitigate any adveise effects diat 1 would result from bnplementation of die remedial action (e.g., construction 1 of an onsite treatment system). |

CD

ARARorTBC

DLACnONSFBCaFK:

A. Occupational Healdi and Safety Act

B. Water

1. dean Water Act \ (CWA): National PoUutam Uschaige Elimination System Requirements

2. General Pretreatment Regulatkms

3. Delaware Environmental Pio-tfytic"

4. Delaware Water Quality Standards

5. EPA Policy for Ground Water Remediation at Supetfiind Sites

6. Deiafvare River Basin Gommissfcn Water

iQuality =D O CD O

Legal Citation

29 CFJl Parts 1904,1910, and 1926

33U.S.C§1251: 40CFJ t .Pan l22

40 CFJl Part 403

l U e 7, Delaware Code; Chapter 60 Section 6010

Stream Quality Standard Section 10

OSWER Directive 9355.4-03

Memorandum of Agreement between the Delaware River Basin Commission and die U.S. Environmental Protection Agency Regbn ID S VIS and V.8)

Classification

Applicable

Applicable

Applicable

AppUcable

To be Considered

Applicable

Requirement Synopsb

Provides occupationa] safety and healdi requiremenci for workers engaged hi onsite ficU actnities

Enforoeable standards for all dbcharges to wraters of die United States.

Standaids for dbchaige to POTW.

Regulations Governing die Ccostiucrioo of Water WeUs

Standards are esuhlbhed hi order to regulate die dbcbarge hito state wateiB In order to mahitain die bitegiity of die water.

lUs policy recommends approaches to ground water remediaition using a pump and treat system.

Regulate restoratkm, enhancement and pteservation of state waters.

Applicability to Selected Remedy

Applicable to onsite work performed during fanplementation of remedial activities

Applicable should remedial action invohie discharge to surface vrater.

Applicable for discharge of extracted || groundwater to POTW. ||

All weUs will be installed and maintained according to state procedures for permitting, construction, and abandonment.

discharge to surface water.

Ihb policy will be considered during die ongoing implementation of the

Applicable if remedial action hivolves dbcfaaige of >50.000 gallona/'day average over any mondi or a U wididrawal of ground water of fl 100,000 gaUont/day or more average | over any mondi. |

ARARorTBC

CAir

1. Delaware Regulations Governing die Control ofAirPoUution

\

2. Qontrbl of Air Emissions froin Air Strippers at Supeifiind Groundwater Sites, June 15, 1989

D. Hazardous Waste

1. United States Department of Tyanspoitation Rules for Ttansportation of Hazardous Materiab

1 2. Dela%vare Regulations

1 Waste

1 Cnie Solid Waste y Dbposal Act (RCRA))

1 a. Standards Applicable 1 to Generaton of 1 Hazardous Waste

JCfe. bijgandaids Applicable

11 fOo l^ansporters of 1 Z^zaidous Waste

BCD IU«

Legal Citation

7 Delaware Code, Chapter 60, Section 6003, Regulation 2, Section 2.4

USWER Directive 93S5.0-28

49 CFJl Parts 107, and 171.1-172.604

Delaware Regulations

Waste

(42 U.S.C § 6901 SI seq.)

r)elaware Regulations Goveniiiig Hazardous Waste, Part 262.10-58 (40 CFJl Pair 262.10-58)

Delaware Regulations Governing Hazardous Waste, Part 263 (40 CFJl Pait 263)

Classification

Applicable

To be Considered

ApplicaUe

Applicable

AppUcable

AppUcable

Requirement Synopsb

Sets fordi die requirement diat a pennit b necessary to operate an air stripper if embsions will exceed Z5 Ibsyday.

Policy to guide die selection of controb for air strippen at

quaUty status of die sitc^ kxation Cue., attainment or non-attainment area).

Regulations for transport of hazardous materiab

Delaware Regubdons Covetning ^ Hazardous Waste Pan 261 (40 CSA. Part 261) define "hazardous waste!*. Ihe regulations Usted bdow apply b> the handling of such hazardous waste.

EstabUshes standaids for generaoois of hazardous wastes including waste determination manifests and pre-iranspon requirements.

Sets forth regubtions for off-tite transporten of hazardous waste in the handling, tianspoitation, and management of die waste.

ApplicabiUty to Selected Remedy

If emissioas exceed ZS Ibsyday then the substantive lequiremenls of die regulation must be met In addition, die emissions from die air stripper must meet die Ambient Air QuaUty tl Standaids set forth hi Regulation 3 of 1 7 Ddawrare Code; C3iapter 60, Section R 6003. 1

To be considered in determining if air H emissions controb are necessary for n an air stripper. Sources most in need jl of controb are those with emissions || rates in excess of 3 Ibsyhour or 15 1 Ibsyday or a potential rate of 10 { tons/year of total VOCs.

'

AppUcable to offsite shipment of || process wastes. U

The collBctfd ground water, || treatment systenu, and hazaidous N wastes generated by die treatment 11 systems shall be handled in || accoidance with regulations Usted 11 below

AppUes to wastes generated by the groundwater treatment systems. . 1]

Apply to any company contracted to transpon hazardous material firom the site.

ro

ARARorTBC

c. Standards forOwnenand Operatoisof Hazardous Waste TVeatment, Storage, and Disposal ' FadUties(TSDF>.

d. RCRA Requirements for Use and Management of Gontainea

e. RCRA Requirements for Tanks Systems

f. RCRA Manifest System, Reootd-keepuig,and Repofling

g. RCRA Land Dbposal Restiictions

Legal au t ion

Delaware Regulations Governing Hazardous Waste, Pan 264 (40 CFJl Pan 264)

Delaware Regulations Govembig Hazardous Waste, Pan 264.170-178 (40 CFJl Pan 264.170-178)

Delaware Regulatkms Governing Hazardous Waste, Pan 264.190-199 (40 CFJl Pan 264.190-199)

Governing Hazardous Waste, Pan 264.70, 264.73-75, and 264.77 (40CFJlPan264.70i 264.73-75, and 264.77)

40 CFJl Pan 268

Classification

AppUcable

AppUcable -(

AppUcable

AppUcable

AppUcable

Requirement Synopsb

Regulations for ownen and operaton of TSDFs which define accqitaUe management of hazardous vrastes.

RequhvmenB for ittnage of hazardous waste hi storage containers.

Requhements for storage or treatment of hazardous waste in tank systems.

Requirements for manifesting for oCbite dbposal of hazardous wastes.

hazardous wastes.

Applicability to Selected Remedy

AppUes to onsite recoveiy and treatment systems and any fodUties to which wastes generated at die site may be taken. ||

AppUcable for onsite treatment systems and temporaiy storage containers.

AppUcable for onsite treatment (yitems and temporaiy storage tanks.

AppUcable for ofibite dbposal of hazardous waste generated by treatment systems.

AppUcable fa: land dbposal of treatment procea wastes. |

o CD CD

cn CO

TABLE 10

f ; • • • ; • . . - •

I"-- /

GROUNDWATER CLEANUP LEVELS

Contaminant

Acetone

Benzene

1,2-Dichloroethane

Manganese

Tetrachloroethene

Toluene

1,1,1 -Trichloroethane

Trichloroethene

Xylene

MCL (ug/1)

-

5

5

50 (SMCg

5

1.000

200

5

10.000

MCLG (ug/i)

-

0

0

-

0

1.000

200

0

10,000

CLEANUP Level (ug/1)

3,500 (DWEL)

5

5

3.000 (NOAEL)

5

1,000

200

5

10.000

MCLG - Maximum Contaminant Level Goal MCL - Maximum Contaminant Level SMCL - Secondary MCL OWEL - Drinking Water Equivalent Level calculated using the

RfD following the procedure in EPA/540/G088-003 NOAEL - No Observed Adverse Effect Level calculated based

on a 70 kg adult consuming 2 liters of water per day

^R000567

RECEIVED AUG 2 6 1993

HNAL

WORK PLAN FOR

REMEDIAL DESIGK SERVICES AT THE

CIIEM-SOLV SITE CHESWOLD, DELAWARE

Prepared fi}r:

Cooperating Pofentially Responsible Parties Ghem-Solv Site

Prepared by:

EA Engineering, Science, and Tectinology, iitc. Berkeley Heights, New Jersey

2& Augu^i:1993 EAa rqjoct;N^>; l^^l^:Ol

TABLE 2-2 ACTION SPECIFIC ARARs FOR DISGKARGE OF TREATED GROUNDWATER CHEM-SOLy, INC, SITE

Pollutant

Arsenic (As)

Ciulmium (Gil)

Copper (Cu)

Cliromium-total (Cr)

Iroji (Fe)

l^ad (Pb)

Nickel CNi)

Mercur>' Olg).

.Silver (Ag) /

Zinc(Zny

Cyanide (Gn)

Anthraccpc

L,2-dichlptot]eo2ene

. Nitroph<aiols

Aceliane

KENT COUNTY POTW LOCAL LIMITS'

Gt;i\i;T£l lAmlifig!?).

. l.Ofl

30

1,000

500

- '000

i.ooo

500

10

•2(xi:

3.000

L,500

3-X 10*

3 x W

3 x 1 0 ^

SURFACB W A r ^ R QUALITY STANDARDS-

Ptish A.c\iie-i:y,i{!)

360

(1.128rin(;hardness)l-3; 828

(0.9422[ln(haKii«;ss)J-i.46'^

16

— • •

Ci ,273[iii(hardQeis)l-l .^60V e

(()-g460IliHban3ncss^rf-3i3612)

2:4,

|l.72[in{liai:dness)l-(;.52)

(g.^473tln(hitr!dnes!OJ^-|.a,860^^ c ' ' '

22

. -.•

• ^

230;

^ . . • •

Fresh Ghronic{>g,'t)

190

{0.7852tliiChanlness)l-3,4W), c

{0;8545Llnthanlnc5s)l-1.465 e

11

ipoo

(i.2?3iln(hnrdness)]-i.705) e

(t). fi46(}tMhardrcss}l+ !; 1645)

0.012

0.12-.

(0.8473lli!{har^ln«»s)]+0,7.^i4) c

5.2

. : - . •

"

150'

--

HUMAN HEALTH STANDARDS"'

Fish Ccnsumpikon (;»g/i')

--

"

•-

" •

-

- . •

5,7()U.

7..1.

40/000

....

270,600 " X

21.800

r^.

- • •

PpUutani

Beiizfine

1,2-Dich]f»roetha]ie

TetrachlyrocLhcne

ToKwne

PGD

Pesticides

1,1,1-TridilorociJiuiie

Trichlorotilhcnc

Maniiiinc.'iC

Nbies: i) The 2) Tiii:

ACL

KENT COUNTY POTW LOC^LLMTS '

General Liinit (ft&'t)

SURFACE ^^^^TER QUALITY STANDARDS-

Ftc^\i Aiimifi^i-i) Fresh Clironic;;:(>g/<);

5,300

:i;i 8,000; :^Q,ooo

5,2^0 ;84Q

;i7i50q:;

0 a :0;014-

0

....

45,000- 21,900;

_ ~ - • „ •

1 HUMAN HEALTH ST.\NDARDS^

Fish;Cpnsuiiipuon (iigi't')

0 ' 123

•4,300

370,000,

36"

- '

500,OD0;

.115

LOO

HCtJim S[>cc:ific ARARs-for the Kent CounQ'POTW .irc^TO^ Kent GouniyljOcalLiinits for TOTW: aciion speqific ARARs for discharge t(VSurJacc;Waicr art compiled from: Siaieof Delawai-e Surface Water Qualitv-Standards and Glea/i Wa:er Surface Water Qudily Siandards,