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16 March 1998 i AGE-NC Project No 95-0137 ' Page 2 of 4 were collected from each well using new, clean, disposable plastic bailers The samples were ' transferred into 40-m1 EPA-approved VOA vials and into 1-liter amber bottles Samples were stored in a chilled container and transported under chain-of-custody to McCampbell Analytical ' Laboratories (MAI) in Pacheco, California Each sample was analyzed in accordance with EPA Method 8015-m modified for total petroleum hydrocarbons quantified as gasoline (TPH-g), in accordance with EPA Method 8015-M modified for total petroleum hydrocarbons quantified as ' diesel (TPH-d), in accordance with EPA Method 8020 for benzene, toluene, ethylbenzene and xylenes (BTE&X) with methyl-tert butyl ether (MTBE), and in accordance with EPA Method 8260m for and MTBE and other oxygenated fuel additives, including tertiary butyl alcohol (TBA), di-isopropyl ether(DIPS), ethyl tertiary butyl ether(ETBE)and tertiary amyl methyl ether(TAME) 3.4. FINDINGS ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION Depth to ground water at the site ranged from 18 40 to 19 25 feet below surface grade(t)sg) The data indicates an average decrease of ground water elevation at the site of 0 6 feet since October 1997 The range of measured ground water depths,between May 1994 and January 1998 are 16 00 to 2105 feet bsg ' The relative ground water elevation ranged from 80 20 to 80 03 feet The gradient for January was calculated to be 0 0064 ft/ft, with an approximate flow direction of N 72 ° W Historically, ground ' water flow direction at the site has varied from northwest to south, consistently at a low gradient Figure 3 -Relative Ground Water Elevation illustrates the contoured relative ground water elevations as measured on 22 January 1998 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES ' TPH- was detected in wells MW-1 u - g though MW 5 at concentrations as high as 9,100 parts per ' billion(ppb,reported as micrograms per liter) TPH-d was detected in wells M W-1 through MW-5 at concentrations up to 2,500 ppb (MW-2) Benzene was detected in the sample from MW-2 at 1,400 ppb, toluene was detected in MW-2 at a concentration of 57 ppb Ethylbenzene and xylenes were detected in samples collected from MW-2 at concentrations of 460 ppb and 830 ppb, respectively MTBE was detected only in the sample from well MW-3 at 6 3 ppb TBA was detected in the samples from wells MW-1, MW-2, MW-3 and MW-4 at concentrations of 23 ppb, 63 ppb, 20 ppb