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i 07 January 1998 AGE-NC Project No 95-0130 Page 2 of 5 2 2 GROUND WATER SAMPLING The ground water levels in monitoring wells MW-1 through MW-5,VW-IC, VW-2A and VW-3A, were allowed to recover for a minimum of one hour prior to sample collection Ground water samples were collected utilizing disposable polyethylene bailers and new nylon rope Sufficient ground water sample was collected from each well to fill three 40-m1 EPA-approved VOA vials containing 0 5 ml 18%hydrochloric acid as a preservative for the samples Care was taken to ensure that visible air bubbles were not present in the VOA vials after filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each round water sample was logged on a chain-of-custody form laced in a chilled container and g p gg y �p transported to a California state-certified laboratory for analysis in accordance with EPA method 8015M for total petroleum hydrocarbons quantified as gasoline (TPH-g), and in accordance with EPA method 8020 for volatile aromatics(benzene,toluene,ethyl benzene and xylene BTE&X)with methyl-tertiary butyl ether(MTBE) The laboratory report(Castle Analytical Laboratory Reference No 1268 and McCampbell Analytical Inc Lab I D 81300 to 81307) and chain-of-custody forms are presented in Appendix B 24 MONITORING WELL SURVEY On 18 December 1997, a California-licensed survey engineer from Baumbach & Piazza Inc surveyed a reference point on the top of each ground water monitoring wells at the site to the nearest 0 01 foot relative to the City of Stockton Bench Mark Datum#92 The results of the monitoring well survey are contained in Table 1 The surveying report (Baumbach & Piazza Job No 9797) is presented in Appendix C 3 0. FINDINGS 3 1 RELA FIVE GROUND WATER ELEVATION AND GRADIENT The depths to ground water from wells MW-1 through MW-5, VW-1C, VW-2A and VW-3A were measured between 47 20 and 48 31 feet below the top of well casings Between June 1997 and September 1997, depth to ground water increased an average 183 feet at the site The ground water elevation data for MW-1 though MW-5 during September's ground water monitoring event is depicted in Figure 3 - Relative Ground Water Elevation Map Advanced GeoEnvironmental,Inc