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EVAX Project B239-02 April 7, 1992 M� Groundwater Flow & Gradient Depth to water measurements were used with wellhead elevation data to calculate the elevation of the groundwater level at each of the monitoring wells. The data is presented in the attached Table 3. A graphical interpretation of the groundwater surface for March 1992 is presented in the attached Groundwater Surface Elevation Map, Figure 3. Groundwater flow direction at the site is inferred to be to the northwest with a gradient of approximately 0.003 vertical per horizontal feet. 1 A review of public files at Environmental Health Divis:on, San Joaquin County Public Health Services indicates groundwater monitoring wells exist on several properties near the subject site. Estimated -from monitoring-well data, groundwater flow directions at these properties are generally consistent with the flow direction inferred for the w subject site. Groundwater flow direction was reported to be north to northwest at the Tracy Public School Bus Facility, 315 East 11th Street, approximately 1,200 feet northwest of the subject site; northwest at Beacon Station 698, 153 East 11th Street, approximately 1,800 feet west of the subject site; and north-northwest at the Genstar Western Stone Facility, 8181 11th Street, approximately 2,800 feet east 1* of the subject site. Laboratory Analyses - Groundwater Laboratory analyses results of water samples (Table 2) indicate the presence of dissolved hydrocarbon products in groundwater. Maximum R hydrocarbon concentrations were found in water sampled from MW-2: 14.1 ppm TPHg, 0.239 ppm benzene, 0.053 ppm toluene, 0.514 ppm ethylbenzene, 5.14 ppm total xylenes, and 0.16 ppm total lead. No floating product or sheen were noted in water sampled from the wells. /A,,sl, ft hydrocarbon odor was noted in water sampled from MW-3. / /V a f ti -7-