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12 August 1996 <br /> AGE-NC Project No 95-0120 <br /> Page 2 of 4 <br /> ' 2 2 GROUND WATER SAMPLING k <br /> Monitoring wells MW-1 through MW-3 were allowed to recover for a minimum of one hour prior <br /> to sample collection Ground water samples were collected utilizing dedicated, disposable <br /> polyethylene bailer's and new nylon rope Sufficient sample was collected from each well to fill <br /> three 40-m1 EPA vials containing hydrochloric acid and a one-liter amber bottle Care was taken to <br /> ensure that no air bubbles were present in the VOAs after filling and capping Ground-water sample <br /> containers were labeled with the well designation, date, time, and samplers initials <br /> 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> ' After collection, each sample was logged on a chain-of-custody form, placed in a chilled container <br /> and transported to a Alpha Analytical Laboratories (AAL), a California state-certified laboratory for <br /> ' analysis Each sample was analyzed for total petroleum hydrocarbons quantified as gasoline and <br /> diesel (TPH-g and TPH-d), volatile aromatics (benzene, toluene, ethylbenzene and xylenes <br /> BTE&X),and methyl-tertiary butyl ether(MTBE) in accordance with EPA methods 5030, 8015M, <br /> M and 602, respectively The laboratory report (AAL Laboratory Batch No 96-0613-010-01 through <br /> 03) and chains-of-custody are presented in Appendix B <br /> ' 3.0. INDI <br /> F NGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The relative surface groundwater elevation on 12 June 1996 is depicted in Figure 3 The depths to <br /> ' ground water in wells MW-1 through MW-3 ranged between 66 56 and 67 20 feet below the top of <br /> the well casings, and on the average, the water table rose approximately 2 6 feet between February <br /> and June 1996 <br /> In February 1996, the ground water gradient at the site was calculated to be 0 001 ft/ft or <br /> ' approximately 5 feet per mile, directed to S 69° E In June 1996, the gradient was calculated to be <br /> 0 0015 ft/ft:(approximately 8 feet per mile),directed S 78°E(Figure 3) Between February and June <br /> 1996, ground water flow direction beneath the site rotated approximately 9' towards the east <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> ' In June 1995 TPH- was detected in round water samples collected from MW-1 and MW-3 at <br /> g g p <br /> concentrations of 72 pg/1 (parts per billion ppb)and 140 pg/l, respectively, TPH-d was detected in <br />