Soil and groundwater contamination was identified at this active municipal refueling station when a 6,000-gallon gasoline underground storage tank (UST) was removed in 1995 by others. Our project team became involved during the Remedial Investigation phase when we took over the project from another consultant. The station, necessary to refuel police and other municipal vehicles, had to remain continuously accessible and operational throughout the investigation, remediation, and monitoring phases. (A new aboveground storage tank system had been installed onsite by others prior to our involvement.)
Remedial investigations confirmed the presence of gasoline-impacted soils and groundwater. A phased remedial approach included several methodologies. First, approximately 2,100 tons of benzene-impacted soils were excavated, and groundwater within the excavation areas was treated with a bio-remediation product (Petrox®). This area was backfilled with compacted clean fill, and monitoring wells were re-installed to continue groundwater monitoring. Eighteen months later, additional remedial actions on-Site included “hot-spot” excavation of 191 tons of benzene-impacted soils, and groundwater within the smaller excavation area was treated with an alternate bio-remediation product (ProvectOx®). This area was backfilled with compacted clean fill, monitoring wells were re-installed to continue groundwater monitoring, and injections were completed in the areas surrounding two monitoring wells downgradient. Quarterly groundwater monitoring and analysis continues.
GZA’s phased remedial approach continues to focus on the remaining, waning area of contamination in compliance with regulatory requirements. Refueling station operations continue undisturbed.
This project was begun by Equity Environmental Engineering prior to its acquisition and continues as a GZA project.