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04 June 1997 <br /> AGE-NC Project No 95-0130 <br /> Page 2 of 4 <br /> utilizing disposable polyethylene bailers and new nylon rope Sufficient ground water sample was <br /> collected from each well to fill three 40-m1 EPA-approved VOA vials containing 0 5 ml 18% <br /> hydrochloric acid as a preservative for the samples Care was taken to ensure that visible air bubbles <br /> were not present in the VOAs after filling and capping Ground water sample containers were labeled <br /> with the well designation, date, time, and sampler's initials <br /> I2 3 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 a California state-certified laboratory for analysis in accordance with EPA Method <br /> 8015M for total petroleum hydrocarbons quantified as gasoline (TPH-g), and in accordance with <br />' EPA Method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylene BTE&X) with <br /> methyl-tertiary butyl ether(MTBE) The laboratory report (Castle Analytical Laboratories Reference <br /> No 1049) and chain-of-custody forms are presented in Appendix B <br /> 1 <br /> 3.0. FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br />' The depths to ground water from MW-1 through MW-5 and VW-1C were measured between 46 32 <br /> and 47 52 feet below the top of well casings Between January 1997 and March 1997, depth to <br />' ground water depth decreased an average 2 62 feet at the site The ground water elevation data for <br /> MW-1 though 5 are in Figure 3 -Relative Ground Water Elevation Map <br />' During the March 1997 monitoring event, ground water was between 3 34 and 13 68 feet above the <br /> screened intervals in monitoring wells MW-1 through MW-5 Therefore, the wells are "drowned", <br /> and may not be fully representative of ground water conditions near the top of the saturated zone, <br />' where fuel hydrocarbons would be expected to have the greatest impact <br /> In January 1997, the gradient was calculated at 0 008 ft/ft (approximately 44 feet per mile) with a <br />' ground water flow direction generally toward the southeast In March 1997, the gradient was <br /> calculated to be approximately 0 005 ft/ft or approximately 28 feet per mile, directed approximately <br /> southeast <br /> 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> TPH- r water samples from wells MW-2 MW-3 MW-5 and VW-I C at <br /> g was detected n and� ground p > <br /> concentrations ranging between 79 and 280,000 pg/1 (microgram per liter or parts per billion ppb) <br />