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Ridge Run PFAS Site

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Site Facts

Municipality/County: East and West Rockhill Townships, Bucks County
HSCA Site Since: 2016
Primary Contaminants of Concern: perfluorooctanoic acid (PFOA) & perfluorooctane sulfonate (PFOS) 

Updated December 2022

Why is DEP Investigating?

  • In September 2016, after a public supply well in the area was found to contain combined concentrations of PFOA and PFOS that exceeded Environmental Protection Agency’s (EPA) 70 parts per trillion (ppt) Health Advisory Level (HAL), and another public supply well was found to contain combined concentrations slightly below the HAL, DEP immediately took steps to begin a thorough investigation of the surrounding area.
  • DEP’s responsibility under the Hazardous Sites Cleanup Act (“HSCA”) (35 P.S. §§ 6020.102-6020.1303) is to select a remedy that is protective of human health and the environment and complies with all statutory and regulatory requirements.

Drinking Water Sampling and DEP's Response

  • Since November 2016, DEP has collected samples from more than 170 private wells within the area of interest surrounding the original contaminated public supply wells.
  • Results of this sampling ranged from non-detect (ND) to 16,360 ppt combined for PFOA and PFOS.
  • 15 homes were identified as having PFOA and PFOS levels above the HAL.
  • The Administrative Record was open for public comment between June 2, 2018 and August 31, 2018.
    • Ridge Run Administrative Record (PDF)
      *Copies of the Administrative Record are available for public review at the DEP office in Norristown, and the East and West Rockhill Township Offices.
  • DEP held a public hearing on July 11, 2018 at the West Rockhill Township Building.
  • On April 18, 2019 DEP issued its Statement of Decision (SOD) and Response to Public Comments Document. In the SOD, DEP selected the Installation and Maintenance of Whole-House Filtration Systems (systems) combined with Restrictions on the Use of Groundwater to address the threats posed by exposure to PFAS contamination above the EPA's HAL in residential privately-owned potable wells within the Site.
  • DEP considers this response to be an interim response as it was expected to cost less than $2 million and less than one year to implement. Additional actions may be needed to achieve a complete and final cleanup for the Site.
  • Since the issuance of the SOD, DEP determined that the necessary circumstances already exist to allow its interim response to exceed 12 months in duration. Based on that determination, DEP no longer planned to transfer maintenance of the filtration systems to the residents after the 12-month period. Instead, DEP plans to monitor and maintain the systems to ensure that they are working properly for the duration of its investigation of the Site.
  • As of March 2022, DEP has installed systems at 13 of the 15 homes with PFOA and PFOS levels above the HAL.
  • Post treatment samples collected to date have indicated that the DEP-installed treatment systems are removing PFOA and PFOS contamination from the drinking water supplies to below the HAL.
  • In February 2022, the DEP published notice of a proposed rule to set drinking water standards for PFOA and PFOS, known as Maximum Contaminant Levels, under the Pennsylvania Safe Drinking Water Act.
  • In anticipation of the finalization of the MCLs in early 2023, DEP expanded the eligibility criteria of the provision of alternative drinking water to homes that were previously sampled by DEP and found to have detections of greater than the proposed MCLs of 14 ppt for PFOA or 18 ppt for PFOS.
  • As of November 2022, DEP has determined that 2 additional homes were eligible to receive bottled water.

Site Investigation

  • DEP is investigating groundwater, soil, and surface water in the area to determine the nature and extent of PFAS in the environment.
  • A March 2020 Site Inspection Report (PDF) prepared by EnviroTrac, Ltd on behalf of DEP, documents Site Investigation activities conducted between 2016 and 2020. Activities included:
    • soil sampling,
    • surface water sampling
    • sediment sampling,
    • the installation of monitoring wells at multiple depths, and
    • one round of groundwater sampling from the monitoring wells.
  • DEP performed sampling of the monitoring wells across the Site in November 2021. Those results can be found here:
  • DEP is looking into all potentially responsible parties. If you have any information related to any potential sources of PFAS contamination, please feel free to provide that information to DEP using the contact information provided below.

Pilot Study

In an attempt to prevent the further spread of PFOA and PFOS from the source area into nearby residential wells, DEP and its contractors are conducting a pilot study consisting of the use of a Regenesis product known as PlumeStop® to create a permeable, underground barrier, which will allow groundwater to flow through it, but not PFOA and PFOS.

  • In January 2021, four injection wells and an additional monitoring well were drilled at the source area and sampled.
  • Injections of PlumeStop® were successfully conducted in April 2021.
  • The results of the post-injection sampling events show sustained and substantial reductions of PFOA and PFOS in monitoring wells within the study area.
  • DEP and its contractors will continue to perform groundwater sampling to determine the success of the pilot study. Updates on the pilot study will continue to be posted on this website in the future.

Timeline (December 2022)

= Completed Steps,  = Current Step,  = Next Steps

Public Water Supply Well detected PFOA and PFOS above HAL9/2016
Drinking water sampling11/2016-Ongoing
Interim Response Proposal6/2/2018
Public Hearing7/11/2018
Issuance of the Statement of Decision (SOD) and Response to Public Comments4/18/2019
Initiated a Suspected Source Property Investigation5/2019
Installation of Site Monitoring Wells10/2019
Sampling of Monitoring Wells12/2019-Ongoing
Installation and maintenance of Whole-House Filtration Systems12/2019-Ongoing
Completion of the Site Inspection Report3/2020
Expansion of the Monitoring Well Network10/2020
Initiation of a Pilot Study 1/2021
PlumeStop® injections4/2021
Additional soil sampling3/2022
Updated Site Investigation ReportEst. Fall 2022

Community Updates

To subscribe to updates, please send an email to: Please indicate in the subject line or text of the email that you’d like to receive updates related to the Ridge Run PFAS HSCA Site.

Contacting DEP

Please direct correspondence or inquiries to one of the following:

  • Site Information: Colin R. Wade, Site Project Officer, at 484-250-5722 or
  • Community and Media Relations: Stephanie Berardi, Regional Communications Manager, at 484-250-5808
  • 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

East Rockhill Township: Phone: (215) 257-9156,

West Rockhill Township: Phone: (215) 257-9063,