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The investigation did not include collection of groundwater samples, as originally proposed in the April 21, 1997 Workplan, based on field observations and guidance from the onsite ' representative from the San Joaquin County PHS/EHD These observations are discussed in Section 5 0 3.2.1 Collection of Soil Samples ' IT collected 14 soil samples from four locations on July 10, 1997 using the Geoprobe DPT rig These Geoprobe sample locations are shown on Figure 2 and described below ' Two of the Geoprobe sample Iocations(SDC-2 and SDC-3) were in closeroximi to the P tY ' former location of the fourth UST (second from the east) which previously exhibited the highest soil concentration of TPH-as diesel (7600 ppm) Soil samples were collected from each of these locations at 15-, 20-, and 25-feet bgs One Geoprobe boring (SDC-1) was located approximately ' 15 feet northeast of location SDC-2 and samples were obtained at 5 foot intervals to a depth of 35 feet at this location The fourth Geoprobe boring (SDC-4) was performed at the second AOC ' (the western-most UST) Samples were obtained at 5 foot intervals to a depth of 25 feet at this location Geoprobe sampling logs are provided in Appendix B From each of the Geoprobe sample locations, soil sample collection was performed using a ' pneumatically driven stainless steel sampling tool To collect the soil samples, the sampler was driven to the target depth, the piston tip retracted into a sample tube and the sample tube ' displaced by approximately 2 feet of soil The sample was then extracted from the borehole to the surface using the DPT ng The sample liner containing the sample was removed from the ' sampler, logged for hydrogeologic and lithologic characteristics by a geologist and screened using a photoionization detector All soil samples were labeled,packaged and stored in an iced cooler for transport under chain of custody manifest to a State of California certified analytical ' laboratory ' 3.2.2 Soil Sample Analyses All soil samples were submitted to Sparger Technology, Inc of Sacramento, California, a state of ' California certifier analytical laboratory (#1614) Soil samples were analyzed for TPH-diesel and benzene,toluene, ethylbenzene and xylenes (BTEX) by EPA Methods 8015/8020 on a standard turn-around time of five working days The analyses were performed in accordance with ' SAC/08-29-97/ENG/7717" 5