The landfill site is bounded to the west and north by railroad tracks and to the south and east by a creek, which eventually discharges to the Delaware River. The landfill has been studied extensively over the past 30 years. A pump-and-treat groundwater remediation system operated from 1992 until approximately 2008. Based on post-remedial groundwater monitoring results, in 2017 USEPA requested the PRP Group further investigate downgradient areas of the landfill site and develop an updated Conceptual Site Model (CSM). EHS Support was retained by the PRP Group to complete a scope of work that included four quarterly groundwater sampling events, vertical groundwater flow analysis in long screen monitoring wells, and development of an updated CSM.
Based on a detailed review of groundwater sampling results and a preliminary CSM, the following data gaps were recognized:
- Configuration of the groundwater flow system downgradient of the landfill
- How, and to what extent are metals being removed by precipitation between the landfill and a residential drinking water wellfield.
To address these data gaps, EHS Support developed a Sampling and Analysis Plan (SAP) for USEPA review that included the following key tasks aimed at collecting additional groundwater geochemistry information:
- Oxygen/hydrogen stable isotope analysis in sitewide groundwater, the creek, and the Delaware River
- Organic acid analysis in sitewide groundwater
- Methane and carbon dioxide gas analysis in sitewide groundwater
USEPA approved the data gap SAP in 2023. A Final Field Investigation Report and Conceptual Site Model update was submitted to USEPA in April 2025 and approved. Future scope of work tasks include a PFAS source area investigation report planned for submittal in late 2025, along with semi-annual groundwater sampling reporting for the foreseeable future.