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r <br /> 21 October 1997 <br /> AGE-NC Project No 95-0121 <br />! Page'2 of 5 <br /> t <br /> 2 2 GROUND WATER SAMPLE COLLECTION ' <br /> Monitoring wells MW-1 through MW-9 were allowed to recover for a minimum of one hour prior <br /> to sample collection Water samples were collected from wells MW-1 through MW-9 utilizing <br /> dedicated, disposable polyethylene bailers and new nylon rope Samples were collected in one-liter <br /> amber bottles and 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a ` <br /> preservative Care was taken,to ensure that visible air bubbles were not present in the VOAs after <br /> 1 filling and capping Ground water sample containers were labeled with the well designation, date, <br /> time, and the sampler's initials <br /> r _ <br /> 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES ry <br />' Each ground water sample was togged on a chani-of- <br /> custody form,placed in a chilled container and <br />' transported to a California state-certified laboratory for analysis of total petroleum hydrocarbons <br /> quantified as gasoline and diesel (TPH-g and TPH-d), volatile aromatics (benzene, toluene, ethyl <br /> benzene and xylenes BTE&X) and methyl tert-butyl ether (MTBE) in accordance with EPA <br /> methods 8015M, 8020 and 8260, respectively The laboratory report (Castle Analytical Laboratory <br /> Reference No 1228) and chain-of-custody forms are presented in Appendix B <br /> r30. FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> In August 1997, the depths to ground water in wells MW-1 through MW-9 ranged between 18 36 <br /> and 20 23 feet below the tops of the well casings Between May and August 1997, ground water <br /> elevation decreased an average of 1 14 feet at the site <br /> IDuring the August 1997 monitoring event, ground water was approximately 3 5 to 12 5 feet above <br /> the screened intervals in monitoring wells MW-1-through MW-9 <br /> In August 1997, the gradient was calculated at 0 006 ft/ft (approximately 32 feet per mile) Ground <br /> water elevation contours suggest a depression-like configuration existed in the area of MW-1 <br /> through MW-9' Furthermore, ground water monitoring data collected in the area of MW-I through <br /> MW-9 suggested that ground water flow on the site was toward the area of MW-1 (Figure 3 - <br /> Relative Ground Water Elevations Map) The cause for this flow character on the site at this time <br /> Iis not presently understood <br /> Advanced CeoEn%ironmental,Inc <br />