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' 3.2 Well Borehole Drilling and Soil Sample Collection ' V&W Drilling (C-57 Lic. # 720904) advanced the monitoring well borehole, MW-5, using hollow stem augers. The borehole was drilled on September 3, 1999, at a location approximately seven feet west of MW-2 (see Figure 2). ' Prior to drilling, V&W decontaminated the auger flights in their yard to minimize the possibility of downhole contamination. V&W drummed the soil cuttings and placed this drum against the ' northern building wall. V&W collected soil samples at approximately 5-foot vertical intervals using a California- modified, split spoon sampler equipped with three, 6-inch long clean brass sleeves. The t borehole was logged based on the 5-foot samples, as well as soil cuttings. First water was encountered at approximately 9 feet below ground surface (bgs). A detailed description of the subsurface lithology can be found in the Boring Log included in Appendix A. JJW retrieved soil samples from the sampler at each 5-foot interval, and sealed one of the three brass sleeves with Teflon sheets, plastic end caps, and duct tape. The samples were labeled, placed on ice in a cooler, and delivered to the analytical laboratory. Chain of custody documentation was maintained. The four collected soil samples were transported under chain- of-custody to TEG-Northern California, Inc. (TEG), a State of California certified analytical laboratory (Certification No. 1671). TEG analyzed for the following parameters per the San Joaquin County directive: ' Total petroleum hydrocarbons as gasoline (TPH-g) (EPA method 8015 modified),- The odified);The aromatic volatile fuel components benzene, toluene, ethylbenzene, and xylenes (BTEX) (EPA method 8020). ' Soil sample analytical results are summarized in Table III. The analytical laboratory data sheets can be found in Appendix B. 3.3 Soil Sample Laboratory Analytical Results Laboratory analyses of the four soil samples revealed increasing levels of gasoline and aromatic volatile hydrocarbon compounds (BTEX) with depth, peaking at 15 feet below the surface. The 15 foot sample value for total petroleum hydrocarbons as gasoline (TPH-g) is 1300 mg/kg and for benzene, 4.1 mg/kg. The last soil sample, collected at 20 feet, revealed a ' significant reduction in petroleum contaminates. TPH-g was not detected (<1.0 mg/kg). benzene was detected just above the detection limit at 0.010 mg/kg. The analytical laboratory data sheets can be found in Appendix B. 3.4 Monitoring Well Construction The monitoring well was constructed using 2-inch diameter, schedule 40 PVC well casing. The screens portion of the wells consisted of factory-perforated PVC casing with 0.020-inch wide slots. The monitoring well was screened from depths of approximately 5 feet to 20 feet. No tchemical cements, glues, or solvents were used in the well construction. The annular space of the well was backfilled with No. 3 Colorado sand to approximately 1-foot ' above the top of the perforated casing. A bentonite seal approximately 2 feet thick was placed ' 2 JJW GEOSCIENCES Inc.