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Hoff VC

Site Facts

Municipality/County: New Hanover Township, Montgomery
HSCA Site Since: 2011
Primary Contaminants of Concern: chlorinated solvents, oil and gasoline components, pesticides, and PAHs

Updated January 2024

Why is DEP Investigating

Drinking Water Sampling and DEP’s Response

  • Between 2011 & 2013, DEP sampled over 40 nearby homes, business, and schools.
  • Sampling by DEP identified nine residential properties with private wells that had contaminants exceeding DEP’s standards.
  • DEP's responsibility under the Hazardous Sites Cleanup Act (HSCA) is to select a remedy that is protective of human health and the environment and complies with all statutory and regulatory requirements.
  • On March 1, 2013, DEP issued a Statement of Decision (PDF) for the Site, selecting the extension of a public waterline as the remedy for contaminated drinking water at the Site.
  • In 2014, 27 total properties, including the nine residential properties with exceedances, were connected to the extended waterline.

Source Investigation and DEP’s Response

  • In the early 1970s, the Swann Oil company, which operated at the Site, was cited several times by DEP’s predecessor, the Pennsylvania Department of Environmental Resources, as well as the Pennsylvania Department of Health for illegal discharges of hazardous substances, including a chlorinated solvent, from a truck-wash to an unnamed tributary of Swamp Creek. Swann Oil also had several oil and kerosene spills during its operation.
  • In the early 1990s, the Site was purchased by its current owner, the Good Oil Company. The Good Oil Company removed many of the Aboveground Storage Tanks and Underground Storage Tanks (UST) improperly and punctured an UST while drilling a monitoring well. DEP’s Storage Tanks Corrective Program has filed orders and liens against Good Oil. Whitetail Disposal Company currently leases property from Good Oil as a truck staging area. In the early 2000’s, Gibraltar Rock Inc. (GRI) purchased several parcels of land less than ½ mile from the Site for a future quarrying operation.
  • Between 2011 & 2014 DEP’s investigation activities included the installation of monitoring wells, surface water sampling, and a vapor intrusion investigation. Details of these activities can be found in the 2014 Project Investigation Report prepared by Leidos on behalf of DEP.
  • August 2016 Groundwater Modeling and Fate and Transport Analysis (PDF) prepared by Tetra Tech, Inc on behalf of DEP.

Concrete Pit Prompt Interim Response

  • In 2016, DEP located a concrete pit on the source property which contained hazardous waste. DEP subsequently removed 8000 gallons of hazardous waste from the concrete pit and 217 tons of contaminated soil surrounding the pit as part of a Prompt Interim Response. The Statement of Decision (PDF) was finalized in June 2017.

Groundwater Remediation Pilot Study

  • In 2018, DEP initiated an in-situ remediation pilot study to address remaining groundwater contamination.
  • Pilot Study Activities conducted between January 2020 and December 2021 are summarized in the September 2022 Hoff VC – Technical Summary Report (PDF). These activities included:
    • Injecting sodium and potassium persulfate and iron into the shallow groundwater to degrade the contaminants near the concrete pit; and
    • Installing in-situ chemical reduction socks in several injection/monitoring wells to further degrade the contaminants.
  • DEP conducted another injection event in May 2022 and reinstalled in-situ chemical reduction socks in several monitoring wells in December 2022.
  • DEP will continue to monitor groundwater quality at the Site on a routine basis as part of its pilot study. The figures below show the latest groundwater results.


= Completed Steps,  = Current Step,  = Next Steps

VOCs detected in Private Drinking Water Well above MCLs7/2011
Drinking water sampling07/2011- 9/2014
Drinking Water Interim Response Statement of Decision (SOD) and Response to Public Comments 3/1/2013
Completion of Drinking Water Interim Response9/2014
Installation of Site Monitoring Wells04/2012-Ongoing
Sampling of Monitoring Wells05/2012-Ongoing
Project Investigation Report8/2014
Discovery of Concrete Pit7/2016
Concrete Pit Prompt Interim Response SOD and Response to Public Comments 6/9/2017
Completion of Concrete Pit Prompt Interim Response6/2018
Initiation of Pilot Study1/2019
ISCO injections (Phase I)11/2020
In-Situ Sleeves Deployment (Phase 2)9/2021
Additional ISCO injections (Phase 3)5/2023
Additional In-situ Sleeves Deployment (Phase 4)12/2022-Ongoing

Contacting DEP

Please direct correspondence or inquiries to one of the following:

  • Site Information: Colin R. Wade, Project Officer, at 484-250-5722 or
  • Community and Media Relations: Stephanie Berardi, Regional Communications Manager at 484-250-5808 or
  • Legislative Inquiries: Lisa Strobridge, Local Government Liaison, at 484-250-5817 or

To schedule an appointment to review files associated with this Site and project, please call the Norristown Office at 484-250-5910.

Municipality Information

New Hanover Twp: Phone: (610) 323-1008,

Information regarding the proposed Gibraltar Rock quarry in New Hanover Township.