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22 June 2004 <br /> . AGE-NC Project No. 98-0520 <br /> ' Page 2 of 4 <br /> After collection, the samples were properly labeled, placed in a chilled container and transported <br /> ' under'chain-of-custody to Cal Tech Environmental Laboratories (CTEL), a California Department <br /> of Health Services (DHS)-certified analytical laboratory, for analysis. The samples were analyzed <br /> for: <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 8015M; and <br /> •, Benzene, toluene, ethyl benzene and xylene (BTEX),and fuel additives; including methyl <br /> tertiary- butyl ether (MTBE), tertiary butanol (TBA), di-isopropyl ether(DIPE), ethyl tert- <br /> ' butyl ether (ETBE), tert-amyl methyFether (TAME), 1,2-dichloroethane (1,2-DCA) and <br /> 1,2-dibromoethane (EDB) in accordance with EPA Method 8260B. <br /> 3.0. FINDINGS <br /> ' . Ground water elevation and, flow direction were determined from field data collected'on <br /> 11 December2003.Hydrocarbon-impact to ground water was quantified from laboratory analysis of <br /> the ground water samples. <br /> ' 3.1. GROUND WATER ELEVATION AND GRADIENT <br /> The elevation of ground water in each well was calculated by subtracting the depth to ground water <br /> ' from the surveyed casing elevations (Table 1). Depths to ground water ranged from 23.24 feet <br /> (MW-7)to 24.03 feet (MW-2) below the tops of the well casings (btoc). Ground water elevations <br /> at the site (not including MW-6) averaged approximately.12.91 feet above mean sea level (MSL) <br /> ' showing an elevation increase of approximately 0.70 feet since the last monitoring event.. <br /> The ground water flow direction was determined using ground water elevation data from water table <br /> ' wells MW-1 through MW-5 and MW-7 through MW-10; elevation data from well MW-6 was not <br /> utilized because well MW-6 is a deep-screen well. During Fourth Quarter 2003, net ground water <br /> flow is toward the northwest under an average gradient of 0.004 foot/foot. Figure 3 illustrates the <br /> ' contoured ground water elevations as measured on 11 December 2003. <br /> 12. ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> ' TPH-g was detected in the water samples collected from wells MW-2 through MW-5, at <br /> concentrations ranging from 100 micrograms per liter•(µg/l)(MW-4)to 490 gg/l(MW-5). Figure 4 <br /> • illustrates the approximate distribution of dissolved TPH-g. , <br /> ' Advanced Geo Environmental,Inc. <br />