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VVATC <br /> A S S O C I A T E S I N C <br /> ANALYTICAL RESULTS <br /> The groundwater samples collected from wells MW1 through MW4, MW6b, and EW I contained <br /> detectable concentrations of TPHg and BTEX constituents. Groundwater samples collected from <br /> wells MW5 and MW6a contained detectable concentrations of TPHg. Groundwater samples <br /> collected from wells MW6b, MW7a, and MW7b contained no detectable concentrations of TPHg <br /> or BTEX constituents. Groundwater samples collected from MW1, MW2, MW4, MW6b, and <br /> EWI contained detectable concentrations of MTBE and groundwater samples from well MW4 <br /> contained detectable concentrations of TBA. Groundwater samples collected from wells MW4, <br /> MW6b, and MW7a contained detectable concentrations of 1,2-DCA. Groundwater samples from <br /> wells MW I through MW7b did not contain detectable concentrations of TPI-Id. Analytical <br /> results of groundwater samples are summarized in Table 2. Laboratory data sheets and chain-of- <br /> custody documentation are contained in Attachment 2. <br /> CONCLUSIONS <br /> Concentrations of TPHg and 1,2-DCA detected in the groundwater samples collected from <br /> MW6a and MW7a, respectively, indicate the hydrocarbon plume extends offsite in the shallow <br /> aquifer. Concentrations of MTBE and 1,2-DCA detected in the groundwater sample collected <br /> from MW6b indicate the hydrocarbon plume extends offsite to the east and in deeper <br /> groundwater. <br /> RECOMMENDATIONS <br /> Based on the results of the fourth quarter 2003 monitoring episode, we recommend the <br /> following: <br /> • Conduct the first quarter 2004 groundwater monitoring and sampling of wells MW 1 <br /> through MW7b and EWI, and analyze the samples for TPHg, TPHd, BTEX MTBE, <br /> ETBE, DIPS, TBA, TAME, 1,2-DCA, and EDB. <br /> • Additional subsurface investigations activities, including the installation of off-site <br /> groundwater monitoring wells, are ongoing and will be detailed in an upcoming report. <br /> • Interim remediation system installation activities are ongoing and will be detailed in a <br /> separate report. <br /> SAEnviromenta11268231QM reports12003 4QR.doc 3 <br />