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l <br /> 1 <br /> 03 October 2000 <br /> AGE-NC Project No '95-0144 <br /> Page 2 of 5 <br /> April 1998 meeting with the PHS-EHD The purge pumps were decontaminated prior to purging <br /> each well by pumping an Alconox solution followed by pumping tap water Approximately three <br /> casing-water volumes (five to twenty gallons) were removed from each of the purged wells <br /> ' Temperature,pH and conductivity ofpurged water were measured at regular purge-volume intervals <br /> using a Hydac water analyzer The recorded field data and logs are included in Appendix A All <br /> purged water was stored in 55-gallon DOT-approved drums on-site <br /> 2 2 COLLECTION OF GROUND WATER SAMPLES <br /> ' The depth to water was remeasured immediatelyfollowing purging in each well to gauge the <br /> recharge rate and to assure a minimum of 80 percent recharge prior to sampling Water samples were <br /> collected from MW-1,MW-2,MW-4,MW-12,MW-13,MW-19A,MW 19B,MW-20A,MW-20B, <br /> MW-21A and MW-21B using new disposable bailers Samples were transferred into 40-m1 EPA- <br /> approved VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative and into 1- <br /> liter amber bottles without preservative The samples were labeled, stored on ace and transported <br /> under chain-of custody to McCampbell Analytical, Inc (MAI), a California Department of Health <br /> Services (DHS)-certified analytical laboratory Each sample was analyzed for <br /> 1 <br /> • TPH-g, TPH-d and TPH-mo in accordance with EPA Methods 5030/8015 Modified, <br /> • BTEX and methyl tertiary-butyl ether(MTBE) in accordance with EPA Method 8020/602, <br /> f <br /> • MTBE, TBA, DIPE, ETBE and TAME, methanol and ethanol by EPA Method 8260 <br /> 1 Modified, and <br /> • Ethylene Dibromide (EDB) and 1,2-Dichloroethane (1,2-DCA) in accordance with EPA <br /> ' Method 8260 Modified <br /> 3.0. FINDINGS <br /> Ground water elevation and flow direction were inferred from field data, hydrocarbon-impact to <br /> ground water was assessed by laboratory analysis of the ground water samples <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> ' The elevation of ground water in each well was calculated by subtracting the depth tq water from the <br /> surveyed casing elevation(Table 1) Between May 2000 and August 2000, ground water elevation <br /> • decreased 1 10 feet in MW-20B and 1 11 in MW-19B Ground water elevation decreased between <br /> Advanced GeoEnviranmcntal,Inc i <br />