Ridge Run PFAS Site
Municipality/County: East and West Rockhill Townships, Bucks County
HSCA Site Since: 2016
Primary Contaminants of Concern:
perfluorooctanoic acid (PFOA) & perfluorooctane sulfonate (PFOS)
Updated July 2019
Why is DEP Investigating?
- DEP is investigating groundwater in the area to determine the extent of PFOA and PFOS in the aquifer underlying the area.
We are referring to the Site as the Ridge Run PFAS HSCA Site.
After one public supply well in the area was found to contain combined concentrations of PFOA and PFOS that exceeded EPA's 70 ppt Health Advisory Limit (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.
Private Drinking Water Investigation
- 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/PFOS.
- There are currently 13 properties which have had results above the HAL and are either equipped with effective carbon filtration systems or are receiving bottled water.
- There are 2 properties which have had results above 40 ppt that are being monitored for any fluctuation above the HAL.
- 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.
In March 2019 - DEP conducted soil and surface water sampling at the Site. DEP utilized the results of the sampling to help determine the best locations for the planned monitoring wells.
During the week of July 15, 2019, DEP plans to begin the drilling of 6 monitoring wells throughout the area of concern.
An example of a monitoring well installation
- The monitoring wells will be installed in a way to allow us to monitor the groundwater at 3 different depths in the aquifer: shallow, intermediate, and deep. The monitoring wells will help us determine the vertical and horizontal extent of the groundwater contamination and the direction of groundwater flow in the area. From start to finish, the installation and construction of the monitoring wells will take approximately one month.
What is DEP Doing to Address the Drinking Water Contamination?
- DEP plans to install Ion Exchange (Resin) Treatment Systems to remove PFAS from drinking water. According to available data, Resin Treatment Systems have been proven to be 100 percent effective for PFAS removal. The initial cost which will be covered by DEP is generally higher than other treatment systems; however, the system requires less maintenance than other treatment systems, leading to lower operating costs. The resins are currently certified for use in drinking water under NSF/ANSI-61 standard.
- Prior to the installation of the systems DEP will collect baseline water quality samples from each home to determine if any additional pretreatment is necessary.
- DEP plans to monitor and maintain the systems it installs for the duration of its ongoing investigation.
- DEP will send letters to each homeowner to ask for permission to install the systems.
- DEP considers this type of response to be an interim response as additional actions may be needed to achieve a complete and final cleanup for the site. DEP's responsibility under HSCA is to select a remedy that is protective of human health and the environment and complies with all statutory and regulatory requirements.
- The response of treatment systems was formally selected in DEP's Statement of Decision (SOD) and Response to Public Comments Document, which was issued on April 18, 2019. 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.
- During the comment period, DEP received multiple comments requesting that the duration of DEP's maintenance of the systems be extended beyond 12 months. In response to these comments, DEP indicated that, at the end of this 12-month period, it would evaluate whether any of the circumstances exist that would allow an interim response to exceed 12 months in duration under the HSCA definition of "interim response" and, if so, whether the 12-month period should be extended accordingly.
- 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 plans 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.
- The Administrative Record was open for public comment between June 2, 2018 and August 31, 2018.
- The information DEP used in formulating its decision was incorporated into the Administrative Record.
- 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.
- Statement of Decision and Response to Public Comments (PDF)*
- Response to Public Comments Appendices (PDF)*
- *The documents were subsequently mailed to all individuals who commented on the proposed response.
- Please note, Pennsylvania's Environmental Quality Board has not proposed a State Maximum Contaminant Level (MCL) before issuance of the SOD. If a State or Federal MCL is issued for PFOS or PFOA that is different from the HAL, DEP will reevaluate the Site and take action as necessary and appropriate.
Please direct correspondence or inquiries to one of the following:
Site Information: Colin Wade, Site Project Officer, at 484-250-5722 or
Community and Media Relations: Virginia Cain, Community Relations Coordinator at 484-250-5808 or
Legislative Inquiries: Rob Fogel, 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.
East Rockhill Township: Phone: (215) 257-9156,
West Rockhill Township: Phone: (215) 257-9063,