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27 July 1998 AGE-NC Project No 95-0121 Page 2 of 4 2 2 GROUND WATER SAMPLE COLLECTION The ground water level in monitoring well MW-3 achieved a minimum of 80 percent recharge prior to sample collection A ground water sample was collected utilizing a disposable polyethylene bailer and new nylon rope Sufficient ground water sample was collected from well MW-3 to fill three EPA-approved 40-m1 VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative Care was taken to ensure that visible air bubbles were not present in the VOAs after filling and ' capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 23 LABORATORY ANALYSTS OF GROUND WATER SAMPLES ' The ground water sample was logged on a chain-o#-custody form, placed in a chilled container and transported to a California state-certified laboratory for analysis in accordance with I • EPA Method 8015M for total petroleum hydrocarbons quantified as gasoline (TPH-g), • EPA Method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylene BTE&X)with methyl-tertiary butyl ether(MTBE), and • EPA Method 8260 for tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyl Iether (ETBE) and tert amyl methyl ether (TAME), and to confirm and quantify MTBE if detected by EPA Method 8020 I 24 SURVEYING On 15 July 1998,a California state-licensed survey engineer from Baumbach&Piazza Inc surveyed the elevation of a reference point on the top of each ground water monitoring well at the site to the ' nearest 0 01-foot relative to the City of Stockton Bench Mark Datum # 4491 The results of the monitoring well survey are contained in Table 2 The surveying report(Baumbach & Piazza Job No 9797) is presented in Appendix C I3.0. FINDINGS 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT IThe depths to ground water in monitoring wells MW-1 through MW-5 were measured at 16 78 to Advanced GeoEnvironmcntal,Inc