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In 2017, four orphan underground storage tanks (USTs) were discovered at a former gas station site slated for redevelopment in a Southern Indiana town. Upon discovery, the USTs were promptly removed. However, during removal, petroleum hydrocarbon (PHC)-impacted soil was observed in the process of excavation. Approximately 100 tons of impacted soil were removed, and subsequent excavation confirmation sampling revealed PHC concentrations above the Indiana Department of Environmental Management (IDEM) soil screening levels. Site investigations were conducted in June 2017 and August 2018 to define the extent of the impacts. EnviroForensics, an Indianapolis-based environmental consulting firm expert in developing site closure strategies, was contracted by the town to pursue regulatory closure. EnviroForensics first delineated the PHC plume in February 2019, identifying the PHC contaminants to be confined in the northern quarter of the site. In the most impacted well-MW-3 total volatile organic compounds (VOCs) concentrations were greater than 3,000 micrograms per liter (μg/L), exceeding IDEM’s Groundwater Screening Levels (i.e., the most conservative action levels) for benzene, 1,2,4- and 1,3,5-trimethylbenzene (TMBs), and naphthalene.

PetroFix case study

No Further Action Granted, Allowing Site Redevelopment to Move Forward