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r r , l 04 November 1996 F AGE-NC Project No 95-0142 Page 2 of 4 22 COLLECTION OF GROUND WATER SAMPLES { I f Water samples were collected from each of the three purged wells using new, clean disposable { fl plastic bailers Immediately upon retrieval, the samples were transferred into 40'ml VOA vials "I containing 0 5 milliliters of 18% hydrochloric acid as a preservative, and were transported iii a , chilled container to McCampbell Analytical, Inc (MAI) in Pacheco, California All samples were analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g) and for volatile aromatics y (benzene, toluene, ethyl benzene and xylenes BTE&X) with methyl-tert-butyl ether (MTBE) in accordance with EPA methods 8015/5030 and 602,respectively ' ,1 J 2 3 COLLECTION OF PURGED WATER SAMPLES One drum of purged ground water was present on-site At the request of Stockton Plating, one water sample was collected from the drum for disposal characterization The sample was collected using ' a' disposable plastic bailer Two 40-m1 VOA vials of water were collected from the drum The sample was labeled and tiansported in a-chilled container under chain-of-custody to MAI 'for analysis The sample was analyzed for TPH-g-and for BTE&X with MTBE in accordance with EPA methods 5030/8015 and 602, respectively r , 3.4 FINDINGS " } I 3 1 AGROUND WATER GRADIENT AND DIRECTION ' The depth to ground water at the site ranged from 35 30 feet to 35,99 feet below the tops of the well casings The average ground water elevation decreased from 64 32 feet in June 1996 to 63 36 feet ' in September 1996,a decrease of approximately one foot Ground water flow direction was northeast f in the wes'te'rn portion of the site and rotated toward the east in'the vicinity of vapor extraction wells VW-1, V,W-2'and VW-3 During the September-1996 monitoring, the hydraulic gradient was approximately 0 014 ft/ft at the west,end of the site and,became more shallow (0 007 ft/ft) toward the east end of the site The relative elevation of ground water is illustrated on Figure 3 - Relative Ground Water Elevation 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES I TPH-g was detected in monitoring well MW-3�at a concentration of 700 per billion (ppb, reported as micrograms per liter) TPH g was also detected in the samples collected from MW-3 and VW-2 at concentrations as high as 560 ppb (V W-2) BTE&X compounds were detected in the samples ,