A former petroleum retail facility was confirmed for polluted soil and classified as an intermediate risk. Geological Resources Inc. worked onsite to remedy the impacted area and successfully reduced the risk classification. After removing all storage tanks, including two that were previously unreported, GRI was able to finalize a Notice of Residual Petroleum (NRP) for the site and the incident was closed.
This site is a former petroleum retail facility and vehicle service garage that had a confirmed release. Soil and ground water assessment activities were ongoing at the site. Although municipal water was available to the site and surrounding properties, the incident was classified by the North Carolina Department of Environmental Quality (NCDEQ) as intermediate risk because of the presence of free product and/or contaminant concentrations that exceeded the Gross Contamination Levels (GCLs).
Geological Resources, Inc. (GRI) was contracted to remove one (1) 10,000-gallon gasoline UST, two (2) 4,000-gallon gasoline USTs, one (1) 1,000-gallon diesel UST, one (1) 2,000-gallon diesel UST and one (1) 2,500-gallon diesel UST, as well as the associated dispensers and product piping from the site. Soil excavation activities were preapproved and scheduled to occur during the Underground Storage Tank (UST) closure in order to remove the petroleum saturated soils contributing to the free product measured in site wells.
The goal of this remediation was to reduce the site’s risk classification.
During tank removal activities, two orphan tanks (one (1) 2,500-gallon UST and one (1) 550-gallon UST) were discovered and removed.
Approximately 829.5 tons of petroleum impacted soils were removed from the UST basin and approximately 8,400 gallons of water and free product were removed using a vacuum truck during the excavation. Confirmation soil samples collected from the sidewalls of the excavation indicated concentrations of requested method constituents that exceeded the soil-to-water Moisture Characteristic Curves (MCCs), however, none of the reported contaminant concentrations exceeded the residential soil cleanup levels.
To evaluate the effect the soil remedial activities had on reducing free product at the site, two monitoring wells, abandoned prior to excavation activities, were replaced and a comprehensive ground water sampling event was conducted. The newly installed wells were gauged and sampled for Volatile Organic Compounds (VOCs) by EPA Method 6200B.
No free product was detected and ground water concentrations did not exceed GCLs. GRI was able to finalize a Notice of Residual Petroleum (NRP) for the site and the incident was closed.