Petroleum Cleanup: Carlisle, Pennsylvania

Groundwater Sciences Corporation (GSC) was retained by a national petroleum company to evaluate multiple sites in anticipation of the company's withdrawal from retail petroleum distribution. One of these sites, in Cumberland County, had historical petroleum impacts from a former underground storage tank (UST) system, a former above-ground tank farm and an associated loading rack. None of these impacts had been addressed. In addition, impacts to soil and groundwater were discovered during the closure of the then-existing retail USTs and associated dispenser islands. The soil at the site is clay-rich limestone residuum and the groundwater is located in the limestone bedrock at depths of 20 to 30 feet below ground surface.

GSC completed the characterization of site soil and groundwater, collecting dozens of soil samples and the installing of 16 bedrock groundwater monitoring wells, including six off-site wells. The groundwater plume had impacted the downgradient federal facility as well as the site. GSC was able to show that the contaminant plume was stable or shrinking by sampling groundwater and performing fate-and-transport analysis. The Pennsylvania Department of Environmental Protection (PaDEP) granted Relief from Liability for the owner using the Site-Specific Standard with institutional controls, thus avoiding the need for active remediation beyond the modest soil excavation activities conducted during the UST closure and loading rack upgrade. The Environmental Covenant addressed both PaDEP and U.S. Department of Defense concerns.