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fl 'R 26 July 1999 • AGE-NC Project No. 95-0106 Page 2 of 4 of sampling and the sampler's initials. The samples were transported in a chilled container under chain of custody to McCampbell Analytical, Inc. (MAI),a California Department of Health Services (DHS)-certified analytical laboratory for analysis. The samples were analyzed for: • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015-Modified, • Volatile aromatic compounds, specifically benzene,toluene, ethylbenzene, and total xylenes (BTEX)with methyl tertiary butyl ether(MTBE)in accordance with EPA Method 8020, and • Oxygenated fuel additives: MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE), ethyl tertiary butyl ether(ETBE) and tertiary amyl methyl ether(TAME) in accordance with EPA Method 8260-Modified. 3.0. FINDINGS Ground water elevation and flow direction were calculated from field data; hydrocarbon-impact to ground water was inferred from laboratory analysis of the ground water samples. 3.1. GROUNDWATER ELEVATION AND FLOW DIRECTION The average relative ground water elevation, not counting MW6, declined an average 0.64 feet since the last monitoring event and the average flow direction was radially northward. The average ground water flow direction in the area enclosed by monitoring wells MW2, MW 1, MW4, MW6, and MW3 was toward the northeast at a gradient of approximately 0.004 ft/ft, and was toward the northwest in the area bounded by MW1, MWS, and MW4 at a gradient of approximately 0.006 ft/ft. Ground water elevation data is presented in Table 1;the contoured ground water elevation data is shown on Figure 3, 3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES Petroleum hydrocarbons were detected in the ground water samples collected from monitoring wells MW-1 and MW-4; MW-1 is located slightly cross- and down-gradient from the former UST excavation and MW-4 is located further north in the generally down-gradient direction. TPH-g was detected at concentrations of 1,000 micrograms per liter (µg/1) and 1,200 µg/l, respectively, in samples from the two wells. Benzene was detected at 190 µg/l and 61 µg11 in samples from MW-I and MW-4, respectively. Other volatile aromatic compounds were detected at concentrations of 80 Advanced GeoEnvironmenial,Inc.