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' SUBSURFACE INVESTIGATION RESULTS AND CLOSURE REPORT <br /> 909 Hammer Lane Stockton Cahfornia <br /> 1.0 INTRODUCTION <br /> This report documents subsurface investigation and well abandonment activities <br /> ' conducted by Fugro West, Inc (Fugro) at the former Exxon Company U S A (Exxon) <br /> RAS No 7-1050, located at 909 Hammer Lane, Stockton, California (Figure 1 ) This <br /> report is based, in part, on information provided to Fugro by Exxon <br /> 11 Purpose <br />' The purpose of the work was to obtain site closure by 1) verifying soil conditions by <br /> collecting soil samples from borings drilled in locations recommended by the San Joaquin <br /> County Environmental Health Department (County), and 2) locating and abandoning the <br /> existing groundwater monitoring wells <br /> 1 2 Scope <br /> 1 The following scope of work was conducted accordingto Fu ro's Standard <br /> g Operating <br /> Procedures (SOP), included in Appendix A <br /> 1 Soil boringSB-A was drilled five feet west of the estimated mated location of product <br /> piping sample S-3-TR5 (Figure 2) The latter sample was collected by Applied <br /> b, Geosystems when the piping was removed in August 1990 It contained 3 3 parts- <br /> per-million (ppm) total petroleum hydrocarbon as gasoline (TPH-g) at a depth of <br /> 5 feet below surface (bs) The boring was drilled to a depth of 40 feet bs and <br /> sampled at five-foot intervals starting at a depth of 10 feet bs The purpose of <br /> these boring samples was to assess the presence and vertical extent of soil <br /> containing hyarocarbons beneath the former piping and to verify the effectiveness <br /> of the vapor extraction system west of the former underground storage tank (UST) <br /> basin <br /> 2 Soil boring SE-B was drilled five feet east of MW-1 (Figure 2) The soil boring was <br /> drilled to a depth of 55 feet bs and sampled at five-foot intervals starting at a depth <br /> of 35 feet bs The purpose of these samples was to determine if groundwater <br /> sample results from 6126187 in MW-1, which indicated concentrations of TPH-g at <br /> 2,750 parts-cer-billion (ppb), benzene at 62 2 ppb, toluene at 141 4 ppb, <br />' ethylbenzene at 155 4 ppb, and total xylenes at 772 4 ppb, became non-detectable <br /> after that date as a result of the static water level in MW-1 dropping below <br /> impacted soii <br />' 3 On September 27, 1994, wells MW-1 through MW-8 were abandoned bYpressure- <br /> grouting the entire length of the wells with a neat cement/bentonite slurry <br />' (Figure 2) <br /> 93473605 ARP z <br /> 1 <br />