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S ' 31 October 2001 • AGE-NC Project No 95-0144 Page 2 of 4 ' intervals using a Hydac water analyzer The recorded field data and logs are included in Appendix A All purged water was stored in 55-gallon DOT-approved drums on-site ' 22 COLLECTION OF GROUND WATER SAMPLES ' The depth to water was remeasured mmediately following purging each well to gauge the recharge rate and to assure a minimum of 80 percent recharge prior to sampling although three wells ' (MW-19A, MW-20B and MW-2I B)were bailed dry and were sampled prior to 80 percent recharge Water samples were collected from each purged well using new disposable bailers Samples were transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acrd as a ' sample preservative and Into 1-liter amber bottles without preservative The samples were labeled, stored on ice and transported under chain-of-custody to McCampbell Analytical, Inc (MAI), a California Department of Health Services (DHS)-certified analytical laboratory Each sample was ' analyzed for • Total petroleum hydrocarbons quantified as gasoline(TPH-g),total petroleum hydrocarbons '. quantified as diesel (TPH-d) and total petroleum hydrocarbons quantified as motor oil (TPH-mo) in accordance with EPA Methods 5030/8015 and 3550/8015, respectively, • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether ' (MTBE) in accordance with EPA Method 8020/602, and • Fuel oxygenated compounds - tertiary butanol (TBA), ch-isopropyl ether (DIPE), ethyl tert ' butyl ether(ETBE), tert amyl methyl ether (TAME) and MTBE by EPA Method 8260M 3.0. FINDINGS ' Ground water elevation and flow direction were inferred from field data, hydrocarbon-impact to ground water was quantified from laboratory analysis of the ground water samples 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT ' The elevation of ground water in each well was calculated by subtracting the depth to water from the surveyed casing elevation(Table 1) Between May 2001 and August 2001, ground water elevation decreased between 0 57 feet and 0 92 feet in the monitored wells The approxirxiate hydraulic ' gradient for,the August 2001 monitoring event was inferred to be 0 003 ft/ft with a flow direction toward the north Ground water elevation contours derived from data collected on 16 August 2001 are depicted in Figure 3 Ground water was between approximately 0 29 feet and 5 57 feet above the 1 Advanced GeoEnvironmentai,Inc 1