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_ Geological Technics Inc Page 7 <br /> 35500 Welty Road,Vernalis,CA <br /> Report-Preliminary Environmental Site Assessment <br /> Protect No 248 2 <br /> February 6, 1995 <br /> • <br /> 3.1 Soil Boring Installation <br /> On January 20, 1995 Geological Technics Inc and well drillers Osterberg and <br /> Stewart Inc mobilized drilling equipment to the site Only two boring <br /> locations were able to be accessed due to very wet field conditions caused by <br /> the recent and heavy rains Hollow stem auger drilling methods with wire <br /> line coring equipment were utilized for this investigation Two soil borings, <br /> SBA and SB-2, were advanced to an approximate depth of 35 feet below <br /> ground surface (Figure 2) <br /> i <br /> During drilling, soil samples were collected for geological and analytical <br /> evaluation at 5 foot intervals starting at five feet below ground surface to the <br /> total depth of 35 feet Soil samples for laboratory analyses were collected in <br /> brass liners using a 2 5 inch modified California split spoon sampler All soil <br /> samples were sealed with aluminum foil, capped, labeled and placed in a <br /> cooler at 4° Celsius for transport to the laboratory following Chain of Custody <br /> protocol An attempt was made to obtain a grab water sample from SB-2 by <br /> inserting a disposable bailer into the hollow stem of the auger The bailer was <br /> unable to recover any fluid, however it came back coated with a dark oily <br /> substance A wipe sample of this substance was collected from the bailer <br /> 31 Field Screening Methods <br /> Because every soil sample collected was not submitted for laboratory analysis, <br /> a screening process was used to gather additional information through field <br /> observation The brass sleeve containing soil next to the sample recovered <br /> for possible laboratory analyses was screened This screening process <br /> particularly observed sediment type, especially grain size and clay content, <br /> moisture content, visible evidence of contamination, I e , color change due to <br /> reduction of Iron or discoloration from hydrocarbons and other pollutants, <br /> and the readings above background on a organic vapor meter (OVM) The <br /> OVM is a field portable photo ionization detector that uses a 10 2 eV lamp to <br /> detect compounds with ionization potential below 10 2 eV (hydrocarbon <br /> range) <br /> In SBA no reading above background (background = 0-1 ppm) was observed <br /> in the screened samples However, in SB-2 elevated readings were observed <br /> that ranged from 0 to 172 parts per million (volume to volume concentration <br /> of compounds ionizable at 10 2 eV) <br /> i <br />