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groundwater contour map was developed The contour map is presented as Figure 2. The contour map suggests that the potentiometric surface of the shallow groundwater is generally flat across the site with a slight eastward trend. The site specific gradient is about 0 0014 ft./ft This data is consistent with last quarters interpretation. Groundwater samples were collected from the on-site wells by EMC personnel. Prior to sample collection, at least three well volumes of groundwater were removed from each well by a portable submersible pump or bailer During the purging of groundwater, pH, conductivity, temperature and turbidity were monitored at selected intervals This data is included in Appendix A along with the gauging data for the reporting period All equipment was cleaned using a solution of Alconox and water followed by two tap water rinses The actual groundwater samples were collected with a teflon bailer equipped with a bottom emptying device before being transferred into the laboratory supplied 40ml VOA vials pending analyses. The chain-of-custody documentation is presented in Appendix B. ANALYTICAL DATA Each groundwater sample was transported on ice in a light proof chest to Smith-Emery Laboratory The samples were analyzed for total hydrocarbons (TPHg) and volatile aromatic compounds (BTEX) by EPA methods 8015 and 8020, respectively Table I presents a summary of the TPHg and BTEX data The complete laboratory reports for the current samples are included in Appendix B The results indicate the presence of TPHg in three of the four wells on-site Detectable TPHg ranged from 0 3 mg/L to 20 0 mg/L Detectable benzene concentrations ranged from 3,200 ug/L to 4,100 ug/L with the highest concentration noted in well MW-2. No detectable TPHg or BTEX were noted in sample MW-4 A benzene iso-con map is presented on Figure 3. A decrease in the dissolved hydrocarbons concentrations was noted this quarter CLOSING Based on the site investigation and monitoring program, it appears that the shallow water zone found beneath the site exhibits the presence of dissolved hydrocarbons The monitoring events accomplished to data suggest the flow direction of groundwater across the site is generally to the south and east-southeast Thrifty will continue to monitor the on-site wells on a quarterly basis If you have any questions, please contact me at (310) 923-9876 Very truly yours, r-� er D'Amico Manager Environmental Affairs cc CVRWQCB, Elizabeth Thayer