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r PHASE VII SUBSURFACE INVESTIGATION San 7uaqu n County Montgomery Ward Auto Sarvtce Center Public Health Services i)eparcment 540p Pacific Avenue Stockton, CA Stte Code 2163 r The hydropunches were advanced by Transglobal Environmental Geochemistry (TEG) under ' the supervision of an EAI California registered geologist The hydropunches were advanced using subsurface sampling equipment which uses hydraulic pressure to push a probe-drive sampler into the soil Unlike split-spoon samplers used in hollow stem auger drilling, the probe-drive sampler (containing a PVC water sampling screen) remains sealed while it is ' pushed into the soil to the desired water sampling depth The probe-drive sampler is then retracted approximately two feet and the water sampling screen is pushed downward approximately two feet to expose the screen to the ground water After the ground water level in the probe tube equilibrated, a length of sterile plastic tubing equipped with a check valve at the intake end was lowered into the probe A ground water ' sample was then obtained by manually forcing ground water through the check valve into the plastic tube The ground water sample was subsequently transferred from the plastic tubing to a sample container for shipment to the laboratory Clean (virgin) tubing was used at each hydropunch location Ground water samples obtained from each hydropunch were placed ' immediately Into four 40 milliliter volatile organic analysis (VOA) vials Each vial was completely filled so that no head space existed between the sample and the lid I The samples were labeled with the sample point identification, EAI project number, time and date, and immediately placed into an ice chest chilled using ice The samples were kept chilled until delivered to the laboratory for analytical testing All samples were logged on chain-of-custody record forms (see Appendix B) The results of testing water samples collected from the hydropunches are shown on Table 7 No soil samples were obtained or tested as part of the hydropunch work 3.2 DRILLING AND SOIL SAMPLING I On February 1, 1996, EAI drilled and sampled one boring (MW-7) at the Montgomery Ward site (see Figure 2) The well location was determined based on the results of testing ground water samples collected from the hydropunches (see Table 7) and a County request that the well be located in an area of the Montgomery Ward site where no dissolved hydrocarbons were detected in ground water based on the hydropunch results The boring was drilled by V&W Drilling of Rio Vista, California (License No C57-710878 Water Well Driller) under the supervision of an EAI California registered geologist The boring was drilled using 10-inch outside diameter continuous flight hollow stem augers The boring was logged in accordance with the Unified Soil Classification System (see Appendix C) Soil samples from the boring were obtained beginning at approximately five feet bgs and at approximately five-foot intervals thereafter, until termination at approximately 70 feet bgs ■ The cmmnlpe SSfpre Cnllpofi-d iicmn civ 7 S-inch d1?,rneter hit thAree 111Ch 1"nn h,-. +„Ik .,, ,.,.,+o.t Y.- b J AVAlb UXU00 LIALleJ ll�l/1_11Lt %d within'a 2 5-inch inside diameter split-spoon drive sampler employed in advance of the augers After sample recovery, the ends of the lowermost tube were covered with aluminum foil and plastic caps taped over the ends Prior to use, all tubes were washed in a solution of Alconox detergent and tap water, and rinsed with tap water The samples were labeled with the sample point identification, depth interval, EAI project number, time and date, individually sealed in "Ziploc" plastic bags, and immediately placed into an ice chest chilled using frozen blue ice IThe samples were kept chilled until delivered to the laboratory for analytical testing All Project No 1232 - 5 - ENVIRONMENTAL AUDIT, INC