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Geolog&Ot7CChXtcslac. Pa-e 2 Soil Investigation Work Plan Project No. 1117.2 November 12,2003 2.1 Tank Location Search GTI has researched the EHD and County Accessor files to determine the actual site of the former UST. Included in these files are Aerial photos, Tentative Subdivision Map of Little John Creek, and previous facility maps. The location of the former tank has been plotted on Figure 3A & 3B — Sample Points for this work plan. Using wooden stakes the location of the boreholes will be mark on the ground. 2.2 Borehole Drilling& Soil Sample Collection Two boreholes will be drilled in the area described above as the location of the former UST. These boreholes will be drilled using a GeoProbe rig owned and operated by V&W Drilling of Isleton, CA (C574 720904). The GeoProbe advances a coring tool with a pneumatic hammer to a selected depth. Upon reaching that depth, a coring tool is opened and advanced further to fill the core barrel. The soil sample enters an acetate cylinder contained in the coring tool. Upon filling, the coring tool is pulled from the hole and the cylinder is removed. The cylinder is then cut and the selected interval is capped with plastic end caps and placed on ice for shipment to the laboratory. The remainder is used for geologic logging. A boring log providing sediment description using the USCS and other field observations as described below will be maintained by a professional geologist working under the supervision of a registered geologist. Two soil samples from each borehole will be submitted to the laboratory for analysis. One of these soil samples will be collected from fifteen feet and one from twenty feet below existing grade. Since only selected soil samples collected will be submitted for laboratory analysis, a screening process will be used to gather additional information through field observation. These observations will include: • 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 • Readings above background on an organic vapor meter(OVM) The OVM is a portable photo ionization detector that uses a 10.6 eV lamp to detect compounds with ionization potential below 10.6 eV (hydrocarbon range). 2.3 Soil Laboratory Analyses Two soil samples from each GeoProbe borehole will be submitted to Sherwood Laboratories of Hilmar(State Certified Laboratory#1400) for the following analysis: • Oxygenates (5)by EPA method 8260 A Chain of Custody will be completed for all samples collected and tracked to ensure sample integrity. The detection limits for these compounds are listed below. DetectionLimits: Oxygenates Soil (Ag/Kg)