Pneumatic Fracturing & Injection of Zero-Valent Iron

This project was implemented as part of a commercial brownfields redevelopment in Maryland. The 19-acre shopping center is impacted, primarily with tetrachloroethene (PCE), from former dry cleaning operations at concentrations up to 41,400 µg/L in the source area, with the majority of the mass in the saprolite and overlying partially weathered bedrock at depths from approximately 55 to 80 feet below ground surface (bgs). Due to the tight geologic formation, pneumatic fracturing and slurry injection of micro-scale zero-valent iron (ZVI) was selected as the full-scale remedial strategy. Pneumatic fracturing created an interconnected fracture network for ZVI delivery in a dense formation that would have typically yielded very low conventional injection flow rates. As ZVI corrodes in the subsurface, it creates strongly reducing conditions in the aquifer to promote both abiotic and biological degradation of PCE and its daughter products.