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t <br /> Groundwater samples were collected from the on-site wells by EMC personnel. Prior to sample <br /> collection, at least three well volumes of groundwater were removed from each well by a <br /> portable submersible pump or bailer During the purging of groundwater, pH, conductivity, <br /> temperature and turbidity were monitored at selected intervals. This data is included in <br /> Appendix A along with the gauging data for the reporting period All equipment was cleaned <br /> using a solution of Alconox and water followed by two tap water rinses. The actual <br /> groundwater samples were collected with disposable PVC bailers equipped with bottom emptying <br /> devices. A new bailer was used for each sample collected Samples were transferred into the <br /> laboratory supplied 40ml VOA vials pending analyses. The chain-of-custody documentation is <br /> presented in Appendix B. <br /> ANALYTICAL DATA <br /> Each groundwater sample was transported on ice in a light proof chest to American Analytics <br /> Laboratory The samples were analyzed for total hydrocarbons (TPHg) and volatile aromatic <br /> compounds (BTEX) by EPA methods 8015 and 8020, respectively. Table 1 presents a summary <br /> of the TPHg and BTEX data. The complete laboratory reports for the current samples are <br /> included in Appendix B. <br /> The results indicate the presence of TPHg in all four wells on-site (ranging from 2.8 mg/L to <br /> 44 mg/L). Benzene concentrations ranged from 100 ug/L to 2,000 ug/L with the highest <br /> concentrations noted in wells MW-3R and MW-4. An interpretation of the dissolved <br /> hydrocarbon plume was not established this quarter as all site well exhibited detectable <br /> concentrations. However, benzene concentrations are plotted on Figure 3 for reference <br /> -CLOSING <br /> Based on the resent site investigation and monitoring program, it appears that the groundwater <br /> 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 /> north-northeast. Thrifty will continue to monitor the on-site wells on a quarterly basis. If you <br /> have any questions, please contact me at (310) 923-9876. <br /> Very truly yours, <br /> Peter D'Amico <br /> Manager <br /> Environmental Affairs <br />