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' Lodi Ready Mix Page 4 Site Closure Report Project No.93.1 May 12, 1995 i ' In summary, Y Y laboratory analyses of soil samples tested from SB-1 (27, 32', 37', & 42') indicate that diesel and gasoline range petroleum hydrocarbons are not present in concentrations above detection limits. The following sections describe the procedures of the subsurface investigation. ' 2.1 Soil Boring Installation On July 6, 1993, Geological Technics Inc. and well drillers Osterberg and ' Stewart Inc. mobilized hollow stem auger and wire line coring equipment to the site. A single soil boring, SB-1, was advanced to a depth of 42 feet below ' ground surface directly south of the former UST excavation (Figure 2). Mr. Mike Collins of the PHS/EHD was on site to observe the drilling activity. During drilling, soil samples were collected for geological and analytical ' 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 ionization detector that uses a 10.2 eV lamp to detect compounds with ionization potential below 10.2 eV (hydrocarbon ' 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 27, 32; 37, and 42 foot intervals were ' submitted to GeoAnalytical Laboratories of Modesto for analyses. These samples were tested for benzene, toluene, total xylenes and ethylbenzene ' (BTEX) by EPA method 8020, Total Petroleum Hydrocarbons as Gasoline (TPH-G) and Total Extractable Petroleum Hydrocarbons (TEPH) by EPA method 8015 modified. 1