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1krCrAVORC ' 2.2 Delta Environmental Investigation On October 24 1990, Delta Environmental collected three soil samples (HB-1, HB-2, and HB-3) from the UST excavation by advancing a hand auger to a depth of 5 5 feet below the concrete slab along its northern edge Analytical results identified no detectable concentrations of TPH-D, TPH as het fuel, or BTEX from samples HB-1 and HB-2 Analytical results from sample HB-3 identified I 1 mg/kg TPH-D 14 mg/kg TPH as het fuel, and no detectable concentrations of BTEX above laboratory detection limits 23 Golden West Environmental Investigation In April 1992, Golden West Environmental supervised the drilling and sampling of three soil borings (PI, P2, and P3) at the site Borings PI and P3 Dere drilled to depths of 25 and 40 feet bgs, respectively Boring P2 (an angled boring) was drilled to a calculated depth of 40 feet A total of 21 soil samples were collected and analyzed from the three borings Analytical results identified trace concentrations of TPH-G, TPH-D, TPH as het fuel (<0 1 mg/kg), and BTEX (<0 1 mg/kg) in soil samples from borings P I and P3 Elevated concentrations of TPH-D (up to 3,100 mg/kg), TPH-G (up to 5,800 mg/kg), TPH asset fuel (up to 3,500 mg/k-), and BTEX (up to 280 mg/kg) were detected in the soil samples from boring P2 The highest concentration of contaminants in boring P2 were Identified in the soil samples collected between 20 feet bas and 40 feet bgs The vertical extent of contamination detected in soil samples from boring P2 was not fully defined Groundwater was not encountered during this phase of the investigation 2.4 Wallace-Kuhl & Associates, Inc Investigation In February 1993, Wallace-Kuhl & Associates, Inc , drilled eight soil borings (MW-I through MW-3, and B I through 135) Borings B I through B5 were drilled around the perimeter of the former UST excavation to 45-50 feet bgs, borings MW-1 through MW-3 were drilled to depths of 60 feet bgs and constructed as four-Inch diameter groundwater monitoring wells In addition to these borings, three hand augered samples (DI-1 DI-2, and DI-3) were collected at a depth of five feet bgs beneath the former fuel dispensers A total of 60 soil boring samples and three groundwater samples were collected from the borings and wells The samples were analyzed for TPH as JP4 het fuel (TPH-JP4), TPH-G, TPH-D, and TPH-motor oil using modified EPA Method 8015, and BTEX using EPA Method 8020 Analytical results Identified no detectable concentrations of TPH-G, TPH-D, TPH-motor oil or benzene above laboratory detection limits in the soil samples TPH asjet fuel was identified in the 15 20, 25, and 30 foot bgs samples from boring 133 Concentrations of aromatic hydrocarbons in these samples ranged from 3 mg/kg of ethylbenzene in the five-foot sample P IDSAISTOCKTOM337200111 STQTR RPT 4