PROPOSED PLAN OF REMEDIAL ACTION

Former Penny Hill Mobil Site Claymont, Delaware

DNREC Project No. DE-1596

October 2016

Delaware Department of Natural Resources and Environmental Control Division of Waste and Hazardous Substances

Site Investigation & Restoration Section 391 Lukens Drive

New Castle, Delaware 19720

CONTENTS

• Figures: 1 & 2 • Glossary of Terms

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PROPOSED PLAN Questions & Answers

Former Penny Hill Mobil Site

What is the Proposed Plan of Remedial Action? The Proposed Plan of Remedial Action (Proposed Plan) summarizes the clean-up (remedial) actions that are being proposed to address contamination found at the Site for public comment. A legal notice is published in the newspaper for a 20-day comment period. DNREC considers and addresses all public comments received and publishes a Final Plan of Remedial Action (Final Plan) for the Site. What is the Former Penny Hill Mobil Site? The Former Penny Hill Mobil Site, located at 2509 Philadelphia Pike, near Claymont, Delaware, is approximately 0.35-acres and is identified as New Castle County Tax Parcel No. 06-095.00-545. The Site’s location is depicted on Figure 1 and the site features are shown on Figure 2. The groundwater, both on and off-site will be addressed under a separate investigation and Proposed Plan. The Site is developed with an approximately 1,521 square foot, single-story building constructed in 1955, which is proposed to be used for commercial use. Historically, the Site was used as a gasoline station at least since 1967 until 1993. Portions of the Site are paved with bituminous concrete. Other areas are stone and/or grass-covered. The Site is bordered to the southeast and northwest by residential sites, and to the northeast and southwest by commercial sites. The Delaware River is located less than 0.5 miles east of the Site. Site topography slopes slightly downward from the northwest to the southeast. What happened at the Former Penny Hill Mobil Site? The Site previously operated as a gasoline station since at least 1967. The Site was developed with two UST fields, two pump islands, and a canopy. When the USTs were removed from the ground in 1993, the Site ceased operating as a gasoline station and was used as an automobile repair facility and other commercial uses. An oil-water separator is present inside the building. The separator is approximately 4 feet by 4 feet in area and 4 feet deep. According to the tenant, the separator was cleaned prior to this BFI. Duffield Associates reviewed the oil-water separator as part of this assessment, no sediment or oily sheens were observed. What is the environmental problem at the Former Penny Hill Mobil Site? Duffield Associates performed a BFI of the Former Penny Hill Mobile Site in 2015. The BFI included collection and analysis of soil, groundwater, soil gas, sub slab vapor, and indoor air samples for regulated organic and inorganic substances. Historic commercial use of the Site was as a commercial gasoline station, and as a result, the Site has been contaminated with petroleum related compounds. Risk calculations indicate that concentrations of regulated substances in shallow and deep soils are unacceptable for future residential use of the Site. Shallow

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groundwater also presents an unacceptable risk for use in residential and commercial exposure scenarios. As mentioned earlier, groundwater, both on-site and off-site, will be addressed under a separate investigation and Proposed Plan. Risk characterization and indoor air sampling has revealed that the vapor intrusion pathway is incomplete; therefore, vapor intrusion at the Site does not appear to be an environmental concern at this time. Petroleum impacted soils are present in the subsurface at the Site. Proper management of these soils under a DNREC-approved Contaminated Materials Management Plan (CMMP) is required in the event they are to be disturbed in the future. What clean-up actions have been taken at the Former Penny Hill Mobil Site? In 1988, petroleum odors were reported in the basements of nearby residences to the southeast of the Site. Vapors were suspected to be migrating to homes along sewer lines and drains into the basements, which were connected to the main sewer along Hillside Road. DNREC investigated the properties and engaged a consultant to conduct a soil vapor assessment of the Site and adjacent properties. At the time of the assessment, the site operated one 10,000‐gallon gasoline, two 4,000‐gallon gasoline, one 3,000‐gallon gasoline, one 3,000‐gallon kerosene, and two 550‐gallon used oil underground storage tanks (USTs). On February 10, 1989, DNREC issued a Secretary’s Order requiring that petroleum be removed from two on-site USTs, due to the failure of tank tightness testing, as well as a hydrogeological investigation to identify and define the extent of off-site impact. Due to the owner’s failure to comply with the Secretary’s Order to resolve off-site impacts, DNREC issued a Cease and Desist Order on February 23, 1989. DNREC assumed control of the incident and applied funds under the Federal LUST Trust Fund Cooperative Agreement between the State of Delaware and the U.S. EPA. On March 3, 1989, DNREC revoked the permit to operate USTs at the Site. The seven USTs were removed from the Site in April 1993. Groundwater monitoring continued quarterly, and later annually, for both on-site and off-site wells from approximately March 1999 through December 2012. Groundwater monitoring, including vapor intrusion into the nearby homes, will be addressed as part of OU-2.

What does the owner want to do at the Former Penny Hill Mobil Site? The owner would like to use the site for commercial purposes. What additional clean-up actions are needed at the Former Penny Hill Mobil Site? DNREC proposes the following remedial actions for the Site, which need to be completed before a Certificate of Completion of Remedy (COCR) can be issued.

1. A proposed Environmental Covenant must be submitted to DNREC for approval within 60 days of the issuance of the Final Plan of Remedial Action.

2. An Environmental Covenant, consistent with Delaware’s Uniform Environmental Covenants Act (7 Del.C. Chapter 79, Subchapter II) must be recorded in the Office of the [County] Recorder of Deeds within 60 days of the issuance of the Final Plan of Remedial

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Action. The Environmental Covenant must include the following activity and/or use restrictions:

[a.] Use Restriction. Use of the Site shall be restricted solely to those non-residential type uses permitted within Commercial, Manufacturing, or Industrial Districts; [b.] Limitation of Groundwater Withdrawal. No groundwater wells shall be installed and no groundwater shall be withdrawn from any well on the Site without the prior written approval of DNREC-SIRS and DNREC Division of Water;

[c.] Compliance with Contaminated Materials Management Plan. All work required by the Contaminated Materials Management Plan must be performed to DNREC’s satisfaction in accordance with the Plan.

3. A Contaminated Materials Management Plan (CMMP) must be submitted to DNREC within 60 days of the issuance of the Final Plan of Remedial Action. The CMMP will provide guidance to enable construction workers to safely handle any potential contaminated groundwater at the Site. DNREC will require the maintenance of the existing monitoring wells and vapor points as part of the CMMP.

4. The CMMP will be implemented upon its approval by DNREC.

5. A request for a Certification of Completion of Remedy (COCR) must be submitted to DNREC within 60 days of the approval of the CMMP.

What are the long term plans for the Site after the cleanup? The Site use will be restricted to non-residential (commercial/industrial) purposes by recording the environmental covenant. The CMMP will be completed and available for the Site. How can I find additional information or comment on the Proposed Plan? The complete file on the Site including the Brownfield Investigation and the various reports are available at the DNREC office, 391 Lukens Drive in New Castle, 19720. Most documents are also found on: http://www.nav.dnrec.delaware.gov/DEN3/ The 20-day public comment period begins on October 23, 2016 and ends at close of business (4:30 pm) on November 14, 2016. Please send written comments to the DNREC office at 391 Lukens Drive, New Castle, DE 19720 to Kristen Thornton, Project Officer or contact 302-395-2600.

Figure 1: Site Location Figure 2: BFI Sampling Plan KLT:tlw; KLT16028.doc; DE 1596 II B-8

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Figure 1

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Figure 2

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Glossary of Terms Used in this Proposed Plan

Brownfield Development Agreement (BDA)

This legal agreement is between a potential developer of a Delaware-certified Brownfields Site and the DNREC. The developer agrees to investigate and cleanup a Brownfields Site under the oversight of the Department in exchange for liability protection.

Brownfield Investigation (BFI) Thorough environmental study of a site which includes 1) sampling of site environmental media and/or wastes on the Site and 2) conducting a preliminary risk assessment using the data collected to determine the risk posed to human health and the environment.

Certified Brownfield

A Brownfield that DNREC has determined is eligible for partial funding through the Delaware Brownfields Program

Certification of Completion of Remedy (COCR)

A formal determination by the Secretary of DNREC that remedial activities required by the Final Plan of Remedial Action have been completed.

Contaminated Materials Management Plan

A written plan specifying how potentially contaminated material at a Site will be sampled, evaluated, staged, transported and disposed of properly.

Final Plan of Remedial Action DNREC’s adopted plan for cleaning up a hazardous site. Hazardous Substance Cleanup Act (HSCA)

Delaware Code Title 7, Chapter 91. The law that enables DNREC to identify parties responsible for hazardous substances releases and requires cleanup with oversight of the Department.

Human Health Risk Assessment (HHRA)

An assessment done to characterize the potential human health risk associated with exposure* to site related chemicals.

Preliminary Risk Assessment A quantitative evaluation of only the most obvious and likely risks at a site

Risk Likelihood or probability of injury, disease, or death. Restricted Use Commercial or Industrial setting SIRS Site Investigation Restoration Section of DNREC, which

oversees cleanup of sites that were contaminated as a result of past use, from dry cleaners to chemical companies