Malvern TCE Superfund Site
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Project Objective

A site in East Whiteland Township, Chester County, Pennsylvania operated as a solvent reclamation facility from 1952 to 1992.

A wooded area surrounded by residential and undeveloped areas bordering the property, the project site consists of a main plant area (MPA) connected to a former disposal area (FDA) by a narrow meadow corridor. Chemclene used a distillation process to remove impurities from the previously used solvents; prior to 1976, sludge from the distillation process was disposed in the FDA. The former processing, chemical storage, and waste management practices at the property have led to solvent contamination in the soil and groundwater. Site remedies included an Accelerated In-Situ Bioremediation (AISB) system in the MPA, and soil vapor extraction (SVE) at the FDA. In its Five-Year Review, the United States Environmental Protection Agency (USEPA) questioned the long-term effectiveness of the SVE system and requested additional investigaton to support revisions to the Conceptual Site Model (CSM) in the FDA.

Geosyntec’s Scope of Services

In the wake of the Five-Year Review, Geosyntec started working with the Chemclene Site Defense Group (CSDG) and conducted the necessary investigation and CSM updates in the FDA, ultimately leading to evaluation of additional remedial actions. Based on observations that dense non-aqueous phase liquid (DNAPL) was present in soil borings and shallow monitoring wells, the investigation was expanded to include the bedrock aquifer (previously not investigated) leading to additional observations of potential DNAPL. The CSDG also asked Geosyntec to provide operation and maintenance (O&M), monitoring, and reporting for the on-going AISB groundwater remedy in fractured rock at the MPA. Geosyntec retained a subcontractor to perform daily O&M under Geosyntec’s supervision.

Notable Accomplishments

Our team of practitioners employed advanced site characterization tools to quickly and accurately assess conditions in soil, overburden groundwater, and bedrock groundwater in the FDA. The results have indicated the presence of several source areas that were not addressed by the former SVE system. Along with new data on site geology and hydrogeology, the new source information was used to update the CSM. Geosyntec is also evaluating several remedial alternatives to complete the cleanup and obtain closure in the FDA. Geosyntec has also provided expert evaluation of biofouling-related conditions associated with the AISB system, and prepared and implemented a well rehabilitation program. We performed a treatability study focused on the evaluation of an alternative electron donor amendment with the goal of reducing the formation of biofouling mass, thus improving system reliability and effectiveness. The results of this study led to the use of a better electron donor material that will reduce the need for well rehabilitation. We also upgraded the AISB system electronics resulting in immediate reduction in O&M labor by reducing the frequency of site visits by at least 50 percent.