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31 January 1997 <br /> AGE-NC Project No 95-0142 <br /> Page 2 of 4 <br /> VOA vials containing 0 5 milliliters of 18% hydrochloric acid as a preservative and placed in a <br /> chilled container The samples were transported in under chain-of-custody to McCampbell <br /> Analytical, Inc (MAI) in Pacheco, California for analysis <br /> All samples were analyzed for total petroleum hydrocarbons quantified as gasoline(TPH-g),volatile <br /> aromatics (benzene, toluene, ethylbenzene and xylenes BTE&X) with methyl-tert-butyl ether <br /> (MTBE) in accordance with EPA methods 8015/5030 and 602 <br /> 23 COLLECTION OF PURGED WATER SAMPLES <br /> Two drums of purged water from previous monitoring events were on present on-site At the request <br /> of Stockton Plating, a water sample was collected from each drum for disposal characterization The <br /> sample was collected using a disposable plastic bailer Two 40-m1 VOA vials of water were <br /> collected from each drum, labeled, placed in a chilled container and transported under chain-of- <br /> custody to MAI for analysis The samples were composrted at the laboratory and analyzed for TPH-g <br /> and for BTE&X with MTBE in accordance with EPA methods 5030/8015 and 602 <br /> i <br /> 3.0. FINDINGS <br /> 3 1 GROUND WATER GRADIENT AND DIRECTION <br /> Ground water at the site ranged from 34 20 feet to 35 99 feet below the tops of the well casings The <br /> average ground water elevation decreased approximately 0 78 feet, from 63 36 feet in September <br /> 1996 to 64 14 feet in December 1996 <br /> Ground water flow direction was northeast in the western portion of the site and rotated toward the <br /> southeast in a trough initiating near monitoring well MW-3 and extending to well MW-2 During <br /> the December 1996 monitoring, the hydraulic gradient was approximately 0 014 ft/ft The relative <br /> ground water elevation data is depicted in Table 1 - Relative Ground Water Elevation The relative <br /> elevation of ground water surface at the site is illustrated on Figure 3 - Relative Ground Water <br /> Elevation <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in samples collected from wells VW-1 through VW-4 at concentrations ranging <br /> from 3,100 to 190,000 parts per billion(ppb, reported as micrograms per liter) BTE&X compounds <br /> .} were detected in samples from each vapor well at concentrations as high as 40,000 ppb (toluene, <br />