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' Site Background Information R.M.B. GARAGE (ERARDI VENTURES) ' 715 North Hunter Street, Stockton, California TPH-g and TPH-d were detected in the ground water samples collected from bonngs B 1 through B4 ' at concentrations as high as 5,400,000 micrograms per liter (µg/1) and 390,000 µg/1, respectively TPH-mo was detected in the ground water sample collected from boring B2 at a concentration of 12,000 µg/1 BTEX compounds were detected in the same samples at concentrations as high as 210,000 µg/1 benzene, 540,000 µg/1 toluene, 630,000 pg/l ethylbenzene and 3,820,000 µg/1 total xylenes (B3) Oil and grease was detected in the samples collected from B1, B2 and 133 at concentrations as high as 1,500,000 gg/l(133) BTEX compounds were detected in the ground water samples at concentrations as high as 8 5 µg/i benzene, 150 µg/l toluene, 120 µg/1 ethylbenzene and 1,300 µg/1 total xylenes Seven additional volatile organic compounds were detected in the ground ' water samples at concentrations ranging from 2,100 µg/l to 2,000,000µg/l Fuel additives were not detected at or above laboratory reporting limits in the ground water samples ' On 04,05 and 25 September 2003, soil borings MW 1 through MW4 and 135-60 feet were advanced at the site Pilot borings MW1 through MW3 and B5 were advanced using a CME-75HT drill ng, equipped with 8 25-inch diameter hollow-stem augers, the drill rig and three-man crew were ' supplied by Mitchell Drilling Environmental Pilot boring MW4 was advanced using a limited- access drill ng(LAR)equipped with 8 25-inch diameter hollow stem-augers,the LAR and three-man crew were supplied by Cascade Drilling Bonngs MWI through MW4 were dnlled to a depth of 40 feet below surface grade (bsg) for completion as ground water monitoring wells Boring B5 was drilled deeper in order to define the ' vertical extent of soil and ground water contamination The planned total depth of boring 135 was 70 feet bsg, as requested by the EHD in their approval letter, however a maximum depth of only 60 feet bsg could be achieved due to the presence of heaving sands I Pilot bona s MW 1 through MW4 were completed g g as ground water monitoring wells using two-inch diameter schedule 40 PVC casing with 0 020-inch slotted screen installed from approximately 20 feet to 40 feet bsg in all four borings,with blank casing extended to the surface The filter pack (No 3 Lonestar sand) was installed from approximately 22 feet to 40 feet bsg A nominal 2-foot bentonite chip plug was then installed above the filter pack and hydrated The wells were then grouted to near the surface with portland cement, and water-tight, traffic-rated well boxes were installed over the wells ' TPH-g was detected in twelve of the soil samples collected from borings MW 1 through MW4 and B5 at concentrations ranging between 13 milligrams per kilogram(mg/kg)in sample MW4-30 and 2,200 mg/kg in sample MW3-30, TPH-d was detected in four samples at concentrations ranging from 20 mg/kg (B5-24) to 200 mg/kg (MW4-40), and TPH-mo was detected in one sample at a concentration of 870 mg/kg(MW3-30) One or more BTEX compounds were detected in samples collected from borings MW 1 through MW4 and B5, the maximum concentrations were detected from sample MW3-30 at 11 mg/kg benzene, 79 mg/kg toluene, 33 mg/kg ethylbenzene and 128 mg/kg total xylenes Advanced GeoEnvironmental,Inc I