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t <br /> 11 June 1999 <br /> AGE-NC Project No 97-0312 <br /> Page 2 of 4 <br /> analyses <br /> For the large domestic well a drain valve was opened on the water storage tank The pump was <br /> r allowed to cycle on and off several tunes For the small domestic well,a faucet between the well and <br /> 11 the water holding tank was opened to allow the pump to cycle several times <br /> f2 2 COLLECTION OF GROUND WATER SAMPLES <br /> The depth to water was re-measured following purging to assure a minimum of 80% recharge prior <br /> to sampling Water samples were then retrieved from each purged well using new disposable bailers <br /> For the domestic wells, a sampling port was opened at the well head Samples were collected from <br /> the sampling port only while the pump was operating, to assure fresh water was sampled Each <br /> I sample was transferred into 40-m1 EPA-approved VOA vials contamXng 0 5 ml of 18%hydrochloric <br /> acid as a sample preservative and into one 1-later amber bottle without preservative The samples <br /> were labeled,placed in a chilled container and transported to McCampbell Analytical, Inc (MAI), <br /> a California Department of Health Services(DHS)-certified Iaboratory in Pacheco, California The <br /> r samples were analyzed for <br /> o Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in <br /> accordance with EPA Methods 5030 and 8015m, <br /> • Volatile aromatic compounds (benzene, toluene, ethylbenzene and xylenes BTE&X) and <br /> methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 60218020, and <br /> G Volatile organic compounds with oxygenated compounds (methyl tertiary-butyl ether <br /> [MTBE], da-isopropyl ether [DIPE], ethyl tert-butyl ether [ETBE], tert-amyl methyl ether <br /> [TAME] and tert-butanol [TBA]) in accordance with EPA Method 8260 modified <br /> 30. FINDINGS <br /> The casing elevation of each well was previously surveyed relative to a City of Stockton bench mark <br /> Ground water elevations were determined by subtracting the measured depths-to-water from the <br /> casing elevations (Table 1) Ground water flow direction was determined by contouring the water <br /> elevations on a scaled site plan(Figure 3) Hydrocarbon impact to ground water was evaluated from <br /> data included in the laboratory report <br /> AdvaxcedGeoEn,tronmentel,Inc <br />