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Lodi Ready Mix Report-Soil Boring Install , Project No. 93.1 August 2, 1993 Page 3 2.1 Soil Boring Installation On July b, 1993, GTI and well drillers Osterberg and Stewart Inc. mobilized drilling equipment to the site. Hollow stem auger drilling methods with wire line coring equipment were utilized fo;r this investigation. One soil boring, SB-1, was drilled to a depth of 42 feet below ground surface directly south of the former UST excavation (Figure 2). : Mr. Mike Collins of the SJCPHS was i on site to observe the driiling activity. Duringdrilling, soil samples were collected for geological and anal tical evaluation at 5 foot intervals starting at ten feet below ground surface to the total depth of 42 feet. Soil samples for laboratory analyses were collected in brass liners using a 2.5 inch modified California split spoon sampler. All soil samples were sealed with aluminum foil, capped, labeled and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. 2.2 Field Screening Methods Because every soil sample collected was not submitted for laboratory analysis, a screening process was used to gather additional information through field observation noting sediment type, especially grain size and clay content, moisture content, visible evidence of contamination, i.e., color change due to reduction of iron or discoloration from hydrocarbons and other pollutants, and the readings above background on a organic vapor meter (OVM)_ The OVM is a field portable photo ioa}ization detector that uses a 10.2 eV lamp to detect compounds with ionization poteintial below 10.2 eV (hvdrocarbon range). No reading above background (background = 1-2 -ppm) was observed for the screened samples. 2.3 Soil Sample Analyses Soil samples collected from the 25, ; 30, 35, and 40 foot intervals were C submitted to GeoAnaiytical Laboratories of Modesto for analyses. These samples were tested for benzene, toluene, total xylenes and ethY lbenzene p , (BTEX) by EPA method 8020 and Total Extractable Petroleum Hydrocarbons (TEPH) by EPA method 8015 modified. The detection limit for benzene, toluene, e.thvlbenzene and total xylenes is 5.0 �tg/kg (ppb) and 5.0/50 mg/kg for TEPH: r