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across the site with an eastward trend. The hydraulic gradient is about 0 0013 This data is <br /> consistent with previous quarterly interpretations <br /> Groundwater samples were collected from wells MW3, MW4, and MW7 by EMC personnel on <br /> August 8, 1995 Prior to sample collection, at least three well volumes of groundwater were <br /> removed from each well by a portable submersible pump or bailer During the purging of <br /> groundwater, pH, conductivity, temperature and turbidity were monitored at selected intervals <br /> This data is included in Appendix A along with the gauging data for the reporting period All <br /> equipment was cleaned using a solution of Alconox and water followed by two tap water rinses <br /> The actual groundwater samples were collected with a teflon bailer equipped with a bottom <br /> emptying device before being transferred into the laboratory supplied 40 ml VOA vials pending <br /> analyses The chain-of-custody documentation is presented in Appendix B <br /> ANALYTICAL DATA <br /> Each groundwater sample was transported on ice in a light-proof chest to American Analytics <br /> The samples were analyzed for total hydrocarbons (TPHg) and volatile aromatic compounds <br /> (BTEX) by EPA methods 8015 and 8020, respectively Table 1 presents a summary of the <br /> TPHg and BTEX data The complete laboratory reports for the current samples are included <br /> in Appendix B <br /> Results of analysis indicate well MW3, which has consistently had high concentrations of <br />• dissolved hydrocarbon, contained 4,600 ppb dissolved benzene Wells MW4 and MW7 did not <br /> contain detectable levels of dissolved benzene A benzene iso-con map is presented on Figure <br /> 2 <br /> CLOSING <br /> Based on the site investigation and monitoring program, it appears that the shallow water zone <br /> found beneath the site exhibits the presence of dissolved hydrocarbons The monitoring events <br /> accomplished to date suggest the flow direction of groundwater across the site is generally to the <br /> east-southeast Thrifty will continue to monitor the on-site wells on a quarterly basis If you <br /> have any questions, please contact Raymond C Fnedrichsen at (310) 923-9876 ext 376 <br /> Very truly yours, <br /> Peter D'Amico <br /> Manager Environmental Affairs <br /> cc CVRWQCB, Elizabeth Thayer <br />