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' 08 May 1997 <br /> . AGE-NC Project No 95-0104 <br />' Page 2 of 4 <br />' sample collection Ground water samples were collected utilizing new, disposable polyethylene bailers <br /> and new nylon rope Sufficient sample was collected from each well to fill three 40-m1 EPA-approved <br /> VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative Care was taken to <br />' ensure that visible air bubbles were not present in the vials after filling and capping Ground water <br /> sample containers were labeled with the well designation, date, time, and sampler's initials <br />' 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br />' Following collection, each sample was logged on a cham-of-custody form, placed in a chilled <br /> container and transported to Alpha Analytical Laboratories (AAL), a California State-certified <br /> Iaboratory for analysis by EPA Method 8015-m for total petroleum hydrocarbons quantified as <br />' gasoline(TPH-g), by EPA Method 8020 for volatile aromatics (benzene, toluene, ethylbenzene and <br /> xylenes BTE&X) and methyl-tertiary butyl ether(MTBE), and by EPA Method 601 for halogenated <br /> volatile organic compounds (HVOCs) <br />' 3.0. FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The depth to ground water in wells MW-I through MW-6 and VW-1 ranged between 60 6.5 and <br /> 6192 feet below surface grade Between December 1996 and March 1997, ground water elevation <br />' at the site increased an average of about 9 00 feet Furthermore, the top of the screen intervals in <br /> wells MW-2 through MW-6 are submerged between 149 feet and 19 35 feet below the ground water <br /> surface <br /> IThe relative ground water surface elevation, as measured on 14 March 1997, is depicted in Figure <br /> 3 In March 1997, the gradient was calculated to be 0 009 ft/ft (approximately 48 feet per mile) and <br /> directed northeastward <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> During the March 1997 sampling event, TPH-g was detected in samples collected from MW-1, MW- <br /> 5, MW-6 and VW-1 at concentrations as high as 5,600 parts per billion (ppb, reported as micrograms <br /> per liter) <br />' BTEX were detected in ground water samples collected from well MW-1, MW-6 and VW-1 <br /> • Benzene was detected in these wells at concentrations as high as 40 ppb, toluene was detected at <br /> concentrations as high as 190 ppb, ethylbenzene was detected at concentrations up to 120 ppb, <br />