Begin Main Content Area

Ridge Run PFAS Site

For more information on PFAS contaminants, what Pennsylvania is doing on a state level, and more, please visit:

Site Facts

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

Updated April 2024

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 the Environmental Protection Agency’s (EPA) 70 parts per trillion (ppt) Health Advisory Level (2016 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.
  • In January 2023, the Pennsylvania Environmental Quality Board amended the Pennsylvania Safe Drinking Water Act setting Maximum Contaminant Levels (PA MCLs) for PFOA (14 ppt) and PFOS (18 ppt). At that time, DEP expanded ongoing efforts regarding its investigation of the surrounding area and offered bottled water to residences known to be above the new PA MCLs.
  • On April 10, 2024, EPA announced the National Primary Drinking Water Regulation (NPDWR) establishing new MCLs for six Per- and Polyfluoroalkyl Substances (PFAS) in drinking water, including PFOA and PFOS. EPA's PFAS site.
  • 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.

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 2016 HAL.
  • The Administrative Record was open for public comment between June 2, 2018 and August 31, 2018. DEP held a public hearing on July 11, 2018.
  • 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) to address the threats posed by exposure to PFOA and PFOS contamination above the 2016 HAL in residential privately-owned potable wells within 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 planned 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 had installed systems at 13 of the 15 homes with PFOA and PFOS levels above the 2016 HAL.
  • In January 2023, DEP began to resample homes in the investigation area with prior detections below the 2016 HAL to determine whether they would exceed the lower PA MCLs of 14 ppt for PFOA and 18 ppt for PFOS.
  • In February 2023, the Perkasie Regional Authority was awarded a $3.5M PENNVEST grant to extend a public waterline to the Site and connect homes at the Site, including those that were above the 2016 HAL.
  • As of March 2024, 51 homes were connected to the waterline. DEP subsequently removed the treatment systems it installed from the homes.
  • DEP is currently evaluating the data from residential well sampling to propose a response action to provide impacted homes located within the area of concern that weren’t connected to the public waterline with an alternative source of potable 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, and
    • the installation of monitoring wells at multiple depths.
  • A September 2022 Technical Summary Report (PDF) and its Appendices (PDF), prepared by Tetra Tech, on behalf of DEP, documents Site activities conducted between 2019 and November 2021. Activities included:
    • potable water treatment and monitoring,
    • monitoring well installation,
    • surface water / shallow groundwater sampling, and
    • the in-situ remediation pilot study (described below).
  • DEP performs routine sampling of the monitoring wells across the Site i. The latest results can be found here:
  • DEP is evaluating performing additional groundwater delineation activities to understand the plume as it relates to the MCLs.

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.

Timeline (April 2024)

= Completed Steps,  = Current Step,  = Next Steps

Public Water Supply Well detected PFOA and PFOS above HAL9/2016
Drinking water sampling11/2016-Ongoing
Drinking Water Interim Response 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
Technical Summary Report9/2022
Expansion of the Monitoring Well NetworkEst. Summer 2024

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 or
  • Legislative Inquiries: Lisa Strobridge P.G., 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,