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6 <br />November 21, 2011 <br />Cardno ERI 2789C.R02 Former Mobil Service Station 99CAS, Stockton, California <br />Site Survey <br />Cardno ERI measured the northings and eastings for wells AS1 through AS5, AS6S, AS6D, SVE1, SVE2, <br />SVE4, and SVE5 while on site for well installation activities. The wells will be surveyed in accordance with <br />Assembly Bill 2886 once the wells have been connected to the remediation system. <br />Waste Manasaement Plan <br />The drill cuttings and rinsate water generated during field activities were temporarily stored on site in DOT - <br />approved, sealed 55 -gallon drums. On October 18, 2011, the soil, sludge, and water were removed from the <br />site. The rinsate water was transported to InStrat, Inc. for recycling. The soil was transported to TPST Soil <br />Recyclers of California for recycling. The sludge was transported to Demenno Kerdoon for recycling. Disposal <br />documentation is included in Appendix F. <br />RESULTS OF INVESTIGATION <br />Site Geolocay <br />During this investigation, the majority of native soil observed beneath the site consisted of clayey silt and silty <br />clay with lenses of poorly graded sand and clayey sand to 80 feet bgs, the maximum depth investigated. <br />Groundwater was not observed during drilling in borings AS6S, SVE1, SVE2, or SVE4, but was first observed <br />between 35 and 45 feet bgs in the other borings. Boring logs are included in Appendix D. <br />Hydrocarbons in Soil <br />Petroleum hydrocarbon concentrations were not reported in soil samples collected from borings AS1 and SVE5, <br />located in the vicinity of the northern former dispenser. Petroleum hydrocarbon concentrations were reported in <br />soil samples collected in the vicinity of the former USTs with maximum TPHd, TPHg, and benzene <br />concentrations reported at 1,300 mg/kg in boring AS3 at 20 feet bgs, 8,400 mg/kg in boring AS4 at 34.25 feet <br />bgs, and 2.2 mg/kg in boring AS4 at 34.25 feet bgs, respectively. Concentrations of MTBE, EDB, 1,2 -DCA, TBA, <br />TAME, DIPE, ETBE, and ethanol were not reported in soil samples collected during this investigation. Select <br />soil analytical results are illustrated on Plate 3. <br />