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09 December 2003 <br /> • AGE-NC Project No 98-0452 <br /> Page 2 of <br /> 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES <br /> Water samples were collected from each monitoring well using new disposable bailers after allowing <br /> I the wells to achieve a minimum 80% recovery of the pre-purge water volume Each water sample <br /> was transferred into laboratory-supplied 40-m1 volatile organic analysis(VOA)vials containing 0 5 <br /> ml 18% hydrochloric acid as a sample preservative After collection, the samples were properly <br />' labeled, placed in a chilled container and transported under chain-of-custody to Cal Tech <br /> Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified <br /> analytical laboratory, and analyzed for <br /> I • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 8015 Modified, and <br /> • Benzene,toluene, ethylbenzene and xylenes(BTEX), and the fuel additives methyl-tertiary- <br /> butyl-ether (MTBE), tertiary butyl alcohol (TBA), dl-isopropyl ether (DIPE), ethyl tertiary <br /> butyl ether(ETBE), and tertiary amyl methyl ether(TAME), 1,2-dibromo ethane(EDB) and <br /> 1,2-dichloroethane (1,2-DCA) In accordance with EPA Method 8260B <br /> I • <br /> 3.0. FINDINGS <br /> Ground water elevation and flow direction were calculated from field data The impact to ground <br /> water was assessed by laboratory analysis of the ground water samples <br /> I <br /> 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION <br /> IThe elevation of ground water In each well was calculated by subtracting the depth to ground water <br /> from the surveyed well head elevations(Table 1) Depths to ground water ranged from 3 99 feet to <br /> 5 44 feet below the tops of the well casings Ground water elevations at the site ranged from <br /> 0 61 feet(MW-3)to 1 23 feet(MW-1)below mean sea level(MSL) The ground water gradient was <br /> calculated to be approximately 0 007 feet/feet with a flow direction toward the southwest(Figure 3) <br /> I Average ground water elevation was 1 01 feet below MSL and increased an average of 0 18 feet <br /> between the June 2003 and September 2003 monitoring event <br /> 3 2 ANALYTICAL RESULTS OF WATER SAMPLES <br /> ITPH-g was detected at a concentration of 200 micrograms per liter(µg/1) In monitoring well MW-2 <br /> which is cross gradient of the former UST area <br /> IAdvanced C eoEnviron mental,inc <br /> I <br />