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GeoCoguaf?ec�inus Srrc Page 2 Soil Groundwater Investigation Report George s Service Project No 425 2 August 5 1997 boring to 50 feet below grade The borings were subsequently converted into 2 inch diameter monitor wells 2.1 Soil Boring Installation In an effort to define the lateral extent of petroleum hydrocarbons, five (5) soil borings, MW- 4 through MW-8 were advanced They were drilled to 22' below grade and converted into monitoring wells The soil borings were drilled using a 8 inch outside diameter (o d ), continuous flight, hollow stem auger owned and operated by V&W Drilling (C57# 720904) Based on hydrologic data from the three existing monitoring wells on site, well placement was based on a northerly groundwater flow direction To define the vertical extent of petroleum hydrocarbons, one (1) soil boring, MW-102, was advanced to 50 feet and then converted to a monitoring well screened from 45 to 47 5 feet below ground surface The boring was drilled in three stages as described below 1 The first stage was drilled with an 8" hollow stem auger down to 39 feet Soil samples were collected at five foot intervals 2 In stage two the 8 inch augers were then pulled from the hole and the borehole was ' drilled out with a 12 inch hollow stem auger to 39 feet This auger then was temporally left in the ground to function as a conductor casing during the installation of the deep well 3 In stage three the 8 inch augers, which had been decontaminated, were lowered down the inside of the 12 inch augers The borehole was there advanced to 50 feet Samples were collected at five foot intervals This method of drilling reduced the possibility of dragging contamination from the shallow contaminated zone into the deeper soil and groundwater A monitoring well permit was secured from San Joaquin County and the agency was notified 48 hours prior to commencing work The subsurface was cleared of underground utilities by notifying Underground Service Alert and by consulting with the property owner Soil cuttings and drilling decontamination water were placed in DOT-17 55 gallon drums and placed alongside the building until there disposal could be arranged 2.1.1 Soil Sampling Procedure Soil samples were collected for geological and analytical evaluation at five foot intervals A boring log providing sediment description using the U S C S and field observations was maintained by a professional geologist working under the supervision of a registered geologist Soil samples were collected in 6 0 inch brass liners using a 2 0 inch modified California split spoon sampler All soil samples were sealed with Teflon sheets, capped with plastic end caps, labeled, and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol Because every soil sample collected was not submitted for laboratory analysis, a screening process was 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 0 eV lamp to detect compounds with ionization potential below 10 0 eV (hydrocarbon range)