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I <br /> to ?1 <br /> Mr Harlin Knoll <br /> Page 2 of 3 <br /> Monitoring wells MW1, MW4, MW5, and MW8 were sampled on May 22, 2001 A mmimum of <br /> three well casing volumes of water was purged from each well prior to sampling The <br /> temperature, specific conductance, and pH of the water were measured and recorded while each <br /> well was purged of the required volume Purged groundwater was placed in labeled drums <br /> approved for storage of liquid waste by the Department of Transportation (DOT) pending <br /> disposal Copies of field purge logs and water level measurements are included in Attachment A <br /> Groundwater samples were submitted to Argon Laboratories (FLAP #2359) for analysis of TPHg <br /> and BTEX utilizing EPA methods 8015M and 8020, respectively <br /> Groundwater Analytical Results <br /> Elevated levels of dissolved gasoline constituents were detected in the groundwater sample <br /> collected from well MW5 and low levels were detected in the samples collected from wells MW <br /> and MW8 No gasoline constituents were detected in the sample collected from well MW4 <br /> Well MW5 contained TPHg. at 66,000 parts per billion (ppb) and benzene at 6,300 ppb, well <br /> MW1 contained TPHg at 290 ppb and benzene at 2 1 ppb, and well MW8 contained TPHg at 210 <br /> ppb and benzene at 4 0 ppb Figure 3 presents a benzene isoconcentration map from the second <br /> quarter analytical results Analytical results are summarized in Table 3 Laboratory data sheets <br /> and chain of custody documentation are included in Attachment B Attachment C contains <br /> • graphical representations of TPHg and benzene concentrations over time in site wells <br /> CONCLUSIONS AND RECOMMENIDATIONS <br /> o Concentrations of dissolved TPHg and BTEX in wells MW 1 and MW5 have been gradually <br /> declining since their recorded highs <br /> 0 Petroleum hydrocarbons periodically detected in well MW8 may represent the approximate <br /> eastern extent of the dissolved contaminant plume <br /> Based upon the histonc non-detect results of constituents of concern in Ground Zero <br /> recommends the following <br /> • Destroy wells MW6 and MW7 under permit from PHS/EHD <br /> e Implement interim groundwater remediation by introducing oxygen releasing compounds <br /> (ORC) in wells MW 1, MW3 and MW5, and reduce sampling frequency of site wells from <br /> quarterly to semi-annually in accordance with recommendations in the June 28, 2001 <br /> Feasibthty Study Report <br /> Knowles ham/reporw2gm2001 doe <br />