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ISite Background Information AGE-NC Project No 99-0657 IPage 2 of 3 a Department of Health Services (DHS)-certified laboratory and analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g), total petroleum hydrocarbons quantified as diesel (TPH-d), volatile aromatics (benzene, toluene, ethyl benzene, and total xylenes BTEX), fuel I oxygenating compounds including methyl tertiary-butyl ether(MTBE)and total lead in accordance with the appropriate EPA Methods On 16 May 1999, the excavation was re-sampled due to inconsistencies between the field observations noted during the tank removal and the analysis ' results TPH-g and the fuel oxygenate MTBE were detected in soil samples collected beneath the former ' USTs at concentrations as high as 260 milligrams per kilogram(mg/kg)and 46 mg/kg,respectively Low levels of BTEX compounds were also detected in the samples collected beneath the former USTs In addition, TPH-d was present at 48 mg/kg in the sample collected from beneath the former ' dispenser area and TPH-g, TPH-d, and MTBE were detected in samples collected from the excavated(stockpiled) soil The stockpiled soil was transported off-site with approval from the EHD and accepted by Mr Dennis Alexander, a local farmer who intended to use the soil to shore up ' levees around his farm 1 • SITE ASSESSMENT ACTIVITIES ' On 04 June 1997,RAH Environmental,Inc over-excavated the original tank excavation to a depth of 22 feet bsg in the area of the previous soil sample locations Subsequently, three soil samples were collected at 22 feet bsg or 6 feet below the original samples and analyzed for TPH-g and BTEX ' with MTBE in accordance with EPA Methods 8015m and 8020, respectively TPH-g and BTEX were not detected in any of the analyzed samples MTBE was detected at 22 feet bsg in all three of the soil samples analyzed, at a maximum concentration of 4 0 mg/kg ' In March 2000, four ground water monitoring wells (MW-I through MW-4) were installed at the site by Advanced GeoEnvironmental, Inc (AGE) A total of 13 soil samples were analyzed for ' TPH-g, TPH-d, BTEX, and the suite of five fuel additives by EPA Method 8260 Modified TPH-g was detected in soil samples analyzed from borings MW-1 and MW-2 at concentrations as high as 2,300 mg/kg and TPH-d was detected at concentrations as high as 590 mg/kg BTEX compounds ' were detected,with the exception of benzene,at concentrations as high as 11 mg/kg, 8 3 mg/kg,and 50 mg/kg, respectively Petroleum hydrocarbons were not detected in soil samples collected from MW-3 and MW-4 MTBE was detected in a sample collected from monitoring well MW-2 at a ' concentration of 0 87 mg/kg(MW2-25)by EPA Method 8260 No other oxygenates were detected in the soil sample analysis ' On 27 and 28 February and 01 March 2002, three soil boring (CPT-1, CPT-2, and CPT-3) were • advanced on- and off-site to total depths of 128 feet bsg utilizing cone penetrometer (CPT) technology Seven hydrologic units(HUs)were identified Significant concentrations of petroleum 1 Advanced Geo Environmental,inc 1