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r 1117 Lone Palm Ave,Suite 201 Modesto,CA 95351 (YV Phone:209-579-2221 J%TC Fax: 209-579-2225 with eastward and northward components, but generally trends northeasterly. The magnitude of groundwater flow in the shallow zone has been calculated to range between 0.0002 ft/ft to 0.003 ft/ft, or approximately 1.2 to 15.8 ft/mile. A summary of groundwater monitoring data is presented in Table 1 and laboratory analytical results of groundwater samples are summarized in Table 2. 3. According to technical reports previously prepared by ATC, petroleum hydrocarbon- affected soils are generally present in the vicinity of the former USTs and the locations of MW2, MW3, MWS, and MW6. Petroleum hydrocarbon-affected soils (low " concentrations) are present at locations away from the former USTs primarily in the vicinity of the capillary fringe at approximately 35 to 40 feet bgs, based on water table conditions in July 2008. The horizontal extent of petroleum hydrocarbons and the presence of these contaminants in the capillary fringe are indicative of groundwater impact, dispersion, and advection. A summary of laboratory analytical results of soil samples collected by ATC is presented in Table 3. y 4. Laboratory analytical results of groundwater samples collected at the site on July 1, 2008, indicate petroleum hydrocarbons were detected in the groundwater samples collected from all of the monitoring wells, with the exception of MW 11. BTEX constituents were detected in the groundwater samples collected from MW2, MW5, and MW6. The highest concentrations of benzene, 2.0 micrograms per liter (µg/L) and 0.64 µg/L, were detected in the groundwater samples collected from MW2 and MW6, respectively. GRO were detected in the groundwater samples collected from MWl, MW2, MW3, MW5, MW6, MW7, MW9, and MW10. The highest concentrations of GRO, 1,800 gg/L and 1,200 µg/L, were detected in the groundwater samples collected from MW2 and MW5, respectively. DRO were detected in all the groundwater samples, with the exceptions of the groundwater collected from MW8 and MW11. The highest concentrations of DRO, 1,800 pg/L and 840 µg/L, were detected in the groundwater samples collected from MW2 and MW9, respectively. MTBE was detected in the groundwater samples collected from MW1, MW2, MW3, MW4, and MW7. The highest concentrations of MTBE, 46 gg/L and 24 gg/L, were detected in the groundwater samples collected from MW3 and MW2, respectively. 1,2-DCA and/or TBA were detected in the groundwater samples collected from MW 1 through MW7 and MW 10. The highest concentrations of 1,2-DCA and TBA were detected in the groundwater samples collected from MW7 and MW3, respectively. Analytical data for groundwater samples collected at the site are summarized in Table 2. The estimated extent of petroleum impacted groundwater is shown on Figures 4 through 8. The locations of the monitoring wells are shown on Figure 3. s:\environmental\22493\reports\feasibility.doc 5 V V