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n from November 1 ], 1995, a groundwater contour map was developed The contour map is presented as Figure 1 The contour map suggests that the potentiometric surface of the shallow groundwater is flowing flat across the site with an eastward trend The hydi aulic gradient is about 0 0008 This data is consistent with previous quarterly interpretations Groundwater samples were collected from wells MW'), MW4, MW5, MW6, MW7 and MW9 by EMC personnel on November 11, 1995 Prior to sample collection, at least three well volumes of groundwater were removed from each well by a poi table 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 40 mi VOA vials pending analyses The cham-of-custody documentation is presented in Appendix B ANALYTICAL DATA Each groundwater sample was transported on ice in a light-proof chest to Arnerican Analytics The samples were analyzed for total hydrocarbons (TPIig) and volatile aromatic compounds (BTEX) by EPA methods 8015 and 8020, respectively Table 1 presents a summary of the TPHg and BTEX data The complete laboratory i epos is foe the cut i ent samples ai e included in Appendix B .) Results of analysts indicate well MW3, which has consistently had high concentrations of dissolved hydrocarbon, contained 16,000 ppb dissolved TPH and 1, 100 dissolved benzene Well MW4 did not contain detectable levels of dissolved TPH and benzene A benzene iso-con map is presented on Figure 2 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 hydrocai bons The monitot ing events accomplished to date suggest the flow direction of groundwatei across the site is generally to the east-southeast Thrifty will continue to monitor the on-site wells on a quarterly basis if you have any questions, please contact Raymond C Fi iedi ichsen at (310) 923-9876 ext 376 I Very truly yours, Peter D'Amico Manager Environmental Affairs cc CVRWQCB, Elizabeth Thayer •