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r 30 October 1996 AGE-NC Project No 95-0111 ' Page 2 of 4 McCampbell Analytical, Inc (MAI) in Pacheco, California Each sample was analyzed for total ' petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d), volatile aromatics (benzene,toluene, ethyl benzene and total xylenes BTE&X) with methyl-tert-butyl ether (MTBE) in accordance; with EPA methods 5030/8015m, 5030/8015m, and 602, respectiyely 23 MONITORING WELL COVER REPAIRS At the request of the q PHS-EHD, a new eight inch well cover was installed over monitoring well , ' MW-1 During the improvements to Giant Line Road, the well cover box had been disrupted and then improperly replaced The damaged well cover box for monitoring well MW-3 was also' replaced Monitoring well locking caps were also replaced on each well to comply with the PHS- EHD requests U ' 30 FINDINGS 3 1 GROUND WATER FLOW DIRECTION AND GRADIENT The relative elevation of ground Nvatei in each well was calculated by subtracting the ground water depth from the surveyed casing elevation (Table 1) All wells were surveyed relative to casing of monitoring well MW I, which had,been assigned an arbitrary casing elevation of 20 feet The relative hound water elevation ianged from 8 70 feet in MW-6 to 9 69 feet in MW-3 Ground ' water clevation decreased an average of 0 75 feet at the site between June and September 1996 A a sheen and drops of free product weie observed in MW-4 and MW-5,but flee product thickness was not measurable - Ground water flow direction at the site was toward the north-northeast, a slight shift more northward since the June monitoring event Ground water gradient at the south end of the site was approximately 0 003 ft/ft The gradient steepens towards the north end of the site to 0 006 ft/ft Ground water surface elevation is depicted in Figur e 3 - Relative Ground Water Elevation 4 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in samples collected from MW-1, MW-2, MW-4 and MNAT-5 at concentrations of 85 micrograms per,literug/l (approximately equivalent to parts per billion ppb), 67 ppb, 110 ppb and 1,200 ppb,respectively TPH-d was detected in samples from MW-1,MW-2, MW-4,MW-5 and �} MW-6 at concentrations of 79 ppb, 94 ppb, 29,000 ppb 43,000 ppb and 96 ppb, respectively