SITE INFORMATION AND CORRESPONDENCE

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Ceological Technics Inc. Page 7 35SQOelty Road, Vernalis,CA Report-Preliminary Environmental Site Assessment Project No. 248? February 6, 1995 3.1 Soil Boring Installation On f anuary 20, 1995 Geological Technics Inc. and well drillers Osterberg and Stewart Inc. mobilized drilling equipment to the site. Only two boring locations were able to be accessed due to very wet field conditions caused by the recent and heavy rains. Hollow stem auger drilling methods with wire line coring equipment were utilized for this investigation. Two soil borings, SB-1 and SB-2, were advanced to an approximate depth of 35 feet below ground surface (Figure 2). During drilling, soil samples were collected for geological and analytical evaluation at 5 foot intervals starting at five feet: below ground surface to the total depth of 35 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. An attempt was made to obtain a grab water sample from SB-2 by inserting a disposable bailer into the hollow stem of the auger. The bailer was unable to recover any fluid, however it came back coated with a dark oily substance. A wipe sample of this substance was collected from the bailer. 3.2 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. The brass sleeve containing soil next to the sample recovered for possible laboratory analyses was screened. This screening process particularly observed 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 alcove background on a organic vapor meter (OW). 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). In SB-1 no reading above background (background = 0-1 ppm) was observed in the screened samples. However, in SB-2 elevated readings were observed that ranged from 0 to 172 parts per million (volume to volume concentration of compounds ionizable at 10.2 eV).