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. it Chemical Monitoring Chemical monitoring for this site consists of <br /> quarterly groundwater sampling of all monitoring wells to delineate plume <br /> movement, monthly groundwater sampling of specific wells related to <br /> intrinsic biodegradation, and quarterly sampling of the vapor extraction <br /> wells Groundwater samples are analyzed for total petroleum <br /> hydrocarbons as gasoline (TPHg) by EPA Method 8015 Modified, and <br /> volatile organic compounds (VOCs) by EPA Method 82608 <br /> iii Well Performance Air sparge wells are checked monthly to venfiy that <br /> air is flowing through each sparge point <br /> d Record the nameplate information from the blower, pumps, and other <br /> mechanical equipment for future reference Compressor information - <br /> Ingersoll-Rand Model SSREP25, Serial Number KE70044 <br /> e Sketch a process flow diagram (PFD), including valves and instrument <br /> locations See attached figure <br /> f If modeling was performed, obtain a copy of the original ISAS modeling <br /> done as part of the system design No information was found to indicate that <br /> modeling was performed as part of original system design <br /> g Are appropriate parameters measured that adequately describe the airflow <br /> paths' (e g , neutron probe response, time-domain reflectometry, electrical <br /> resisstivity tomography, dissolved oxygen concentrations, air bubbling, air <br /> pressure measurements) Air pressure measurements have been collected for <br /> ISAS wells Additionally, ENSR collects concentrations of dissolved oxygen <br /> during quarterly monitoring events <br /> h Are monitoring points distributed adequately in cross section to determine <br /> if sufficient air contact is achieved in all three dimensions? Yes Air contact <br /> appears to sufficient in the current target areas Additional sparge wells <br /> screened beneath unit B in the vicinity of MW-3 and MW-11 would provide more <br /> coverage where dissolved concentrations of petroleum hydrocarbons are the <br /> highest <br /> i Are measurements of water table fluctuations made to determine the <br /> possible effects on the ISAS system performance9 Are these <br /> measurements made with adequate frequency? Yes Depth to groundwater <br /> measurements are collected from all wells on a quarterly basis ISAS wells are <br /> screened within each unit (A through D) beneath the site <br /> Have tracer tests been conducted to verify air flow paths and adequate <br /> travel timeslvelocitiesl No <br /> 5 Performance Analysis Calculations <br /> a Prepare hydrogeologic cross sections using available well/boring logs, <br /> including the sparging wells, if no cross sections of the area of concern are <br /> available Evaluate the potential for preferential flow paths or hydrogelogic <br /> boundaries not considered in design and which may affect system <br /> performance Cross sections for this site are available which ENSR has <br /> modified to include data from selected sparge wells <br />