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22 November 1996 <br /> AGE-NC Project No 95-0130 <br />' Page 2 of 4 <br />' polyethylene bailers and new nylon rope Sufficient ground water sample was collected from each <br /> well to fill three 40-m1 EPA vials containing 0 5 ml 18% hydrochloric acid as a preservative for the <br /> samples Care was taken to ensure that visible air bubbles were not present in the VOAs after filling <br /> and capping Ground water sample contamers were labeled with the well designation, date, time, and <br /> sampler's initials <br /> 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> Each ground water sample was logged on a chain-of-custody form, placed in a chilled container and <br /> transported to Castle Analytical Laboratories (CAL), a California state-certified laboratory for <br /> analysis of hazardous materials Each sample was analyzed for total petroleum hydrocarbons <br /> quantified as gasoline (TPH-g), and volatile aromatics (benzene, toluene, ethyl benzene and xylene <br /> BTE&X), with methyl-tertiary butyl ether (MTBE) in accordance with EPA methods 5030 and 602, <br /> respectively The laboratory report (CAL Laboratory No 915) and chain-of-cu stody forms are <br /> presented in Appendix B <br /> 3 0. FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> Ground water depths at the site ranged from 50 48 to 51 60 feet Ground water at the site declined <br /> an average 0 44 feet between July 1996 and October 1996 Ground water is approximately 3 48 to <br /> 9 52 feet above the tops of the screen intervals of monitoring wells MW-1 through MW-4, and is <br /> approximately 0 79 feet below the top of the screen interval of MW-5 <br /> In July 1996, the gradient was calculated at 0 005 ft/ft (approximately 28 feet per mile) with a ground <br /> water flow direction generally S 8°E In October 1996, the gradient was calculated at 0 006 ft/ft <br /> (approximately 31 7 feet per mile) with a ground water flow direction generally S 20°E (Figure 3 - <br /> Relam,e Ground Water Elevations Map) Between July and October 1996, ground water flow <br /> direction beneath the site rotated approximately 12° eastward <br /> I3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in ground water samples from wells MW-2, MW-3, MW-5 and VW-1C at <br /> concentrations ranging between 250 µg/l and 140,000 µg/1 (microgram per liter or parts per billion <br /> Ppb) <br /> Benzene was detected in ground water samples from wells MW-1 through MW-5 and VW-IC at <br />