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24 November 1997 <br /> AGE-NC Project No 95-0104 <br /> Page 2 of 4 <br /> 2 2 GROUND WATER SAMPLING <br /> Following purging, the monitoring wells were allowed to recover for a minimum of one hour prior <br /> to sample collection Ground water samples were collected utilizing new, disposable polyethylene <br /> bailers and new nylon rope Sufficient sample was collected from each well to fill three 40-m1 EPA- <br /> approved VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative Care was <br /> taken to ensure that visible air bubbles were not present in the vials after filling and capping Ground <br /> water sample containers were labeled with the well designation, date, time, and sampler's initials <br />' 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br />' Following collection, each sample was logged on a chain-of-custody form, placed in a chilled <br /> container and transported to Alpha Analytical Laboratories (AAL), a California state-certified <br /> laboratory 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) with methyl-tertiary butyl ether (MTBE), and by EPA Method 8260 for tertiary <br /> butanol(TBA), di-isopropyl ether (DIPE), ethyl tert butyl ether (ETBE) and tert amyl methyl ether <br /> (TAME), and to confirm and quantify any MTBE detected by EPA Method 8020 <br />' 3.0. FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The depth to ground water in wells MW-1 through MW-6 and VW-1 ranged between 69 88 feet and <br /> I 70 86 feet below tops of well casings Between June and September 1997, ground water elevation <br /> at the site decreased an average of approximately 5 69 feet Furthermore, the top of the screen <br /> intervals in wells MW-2, MW-3 and MW-4 are submerged between 9 63 feet and 10 12 below the <br />' ground water surface <br /> The relative ground water elevation, as measured on 26 September 1997, is depicted in Figure 3 The <br />' maximum September gradient was calculated to be 0 006 ft/ft (approximately 32 feet per mile) and <br /> directed north-northeast and south-southwest <br /> 1 <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br />' During the September 1997 sampling event, TPH-g was detected in samples collected from MW-1, <br /> • MW-5, MW-6 and VW-1 at concentrations as high as 10,000 parts per billion (ppb, reported as <br /> I <br /> 4dvanced C,eaFnvirnnmenf,il Int <br /> r <br />