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Y �+ 07 February 2006 AGE-NC Project No. 97-0360 Page 2 of 7 22. UNDERGROUND STORAGE TANK REMOVAL On 12 August 1997, one 10.000-gallon diesel UST was removed from the site by Stockton Service Station, Inc. Product line(s) were also removed during excavation of the UST. During the UST removal,two soil samples were collected from the floor ofthe UST excavation,four soil samples from the stockpiled soil, and one grab ground water sample. Total petroleum hydrocarbons quantified as diesel (TPH-d) were reported in each of the soil samples analyzed at concentrations as high as 6,200 milligrams per kilogram (mg/kg). BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) were not detected in the soil samples analyzed. TPH-d and BTEX compounds were detected in the grab ground water sample at concentrations of 31,000 micrograms per liter(µg11) TPH-d, 38 flg/l benzene, 12 pg/I toluene, 53 pg/l ethylbenzene, and 68 µg/l xylenes. 2.3. PREVIOUS SITE ASSESSMENTS On 25 October and 24 November 1999, Lush Geosciences, Inc. excavated trenches TR-1 through TR-9 to maximum depths of approximately 10 feet to 12 feet below surface grade(bsg)to assess the soil and ground water conditions at the site adjacent to J.B. Murphy Trucking. The trenches were located in close proximity to the former UST location on the property of J.B. Murphy Trucking. Soil samples were collected from depths of 8 feet and 10 feet bsg, and ground water was collected from depths of 9 feet and 10 feet bsg. TPH-d was detected in soil samples collected from trenches TR-1 through TR-4 at concentrations as high as 2,140 mg/kg. TPH-d was also reported in the grab ground water sample collected at a concentration of 508 mg/l. Only low to non-detectable concentrations of BTEX compounds were detected. U n?zI 1q�06, On 13 July 2000, eight soil probe borings (P1 through P8) were advanced at the site as part of assessment activities related to the f�rtormer UST/-TPH-g was detected in the 10-foot soil sample collected from P4 at a concentration of 46 mg/kg. The only BTEX compound detected in soil was ethylbenzene, which was detected in the 10-foot soil sample collected from boring P4 at a concentration of 0.009 mg/kg. TPH-d was detected in soil samples collected from probe borings P 1, P4,and P5 at concentrations as high as 3,400 mg/kg(P4-10). Fuel oxygenated compounds were not detected at or above laboratory reporting limits. Grab ground water samples were collected from borings P 1 through P8 and were submitted to a California Department of Health Services (DHS)-certified laboratory for analysis. TPH-g was detected in the ground water samples collected from P1, P2, and P4 at concentrations of 3,100 micrograms per liter (Vtg/l), 1,300 µg11, and 2,100 µg11. respectively. TPH-d was detected in the ground water samples collected from P1 through P8 at concentrations as high as 2,900,000 pL 1 Advanced GeoEnvironmental,Inc.