At the site of a former petroleum retail facility, GRI was contracted to remove two 4,000-gallon gasoline Underground Storage Tanks (USTs), one 4,000-gallon diesel UST, and associated dispensers and product piping. They also excavated and transported a total of 168.82 tons of overburden soil and 21.52 tons of petroleum contaminated soil to a permitted disposal facility, then conducted a Limited Site Assessment in order to confirm safe soil contaminant levels.
The site was a former petroleum retail facility and was vacant and in the process of being sold. Geological Resources, Inc. (GRI) was contracted to remove two 4,000-gallon gasoline Underground Storage Tanks (USTs), one 4,000-gallon diesel UST, and associated dispensers and product piping. Over-excavation activities were conducted in the vicinity of the dispenser island following UST removal based on observations by GRI field personnel. Neither ground water nor free product was observed during excavation activities. A total of 168.82 tons of overburden soil and 21.52 tons of petroleum contaminated soil was excavated and transported to a permitted disposal facility.
During UST removal, soil samples were collected from beneath the three 4,000-gallon gasoline and kerosene USTs, dispenser islands, product piping, soil stockpile and each truckload. Concentrations of benzene, toluene, ethylbenzene and/or xylenes that exceeded the soil-to-water MCCs were reported in ten (10) soil samples. Concentrations of TPH-GRO and/or TPH-DRO that exceeded the RALs were reported in (4) four soil samples.
Following over-excavation, a confirmation soil sample collected from below the dispenser island did not exceed the soil-to-water MCCs, indicating the release was remediated as part of the initial abatement activities. Based on those results, GRI recommended a Limited Site Assessment (LSA) be conducted.
GRI conducted Phase I LSA activities and the receptor survey identified no receptors within any radius of the site. One monitoring well was installed and sampled in the vicinity of the former dispenser island.
Reported in the ground water sample were concentrations of benzene, xylenes, MTBE, naphthalene, 1,2-dichloroethane, n-propylbenzene, 1,2,4-trimethylbenzene, EDB, C5-C8 aliphatics and C9-C10 aromatics that exceeded the Maximum Allowable Concentrations (MACs), however, none of the reported contaminant concentrations exceeded the Gross Contamination Levels (GCLs).
Reported in the two soil samples collected during the installation of the monitoring well were concentrations of one or more individual BTEX constituents, naphthalene, n-butylbenzene, isopropylbenzene, methylene chloride, n-propylbenzene, styrene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 1-methylnaphthalene, 2- methylnaphthalene, C5-C8 aliphatics, C9-C10 aromatics, C9-C18 aliphatics and/or C11-C22 aromatics that exceeded the soil-to-water MCCs. Concentrations of 1-methylnaphthalene, 2-methylnaphthalene, C9-C10 aromatics, C9-C18 aliphatics and/or C11-C22 aromatics exceeded the residential soil cleanup levels.
Based on these results, the site was risk classified as low. NCDEQ granted a status of No Further Action (NFA) after GRI completed the Notice of Residual Petroleum (NRP).