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10 <br /> Figure 6 shows the anticipated capture zone achieved by pumping from TEX-1 at 10 gpm <br /> and ATR-2 4, and 5 at 1 gpm These results were obtained using the analytical groundwater <br /> flow model "Quickflow" (by Geraghty & Miller, Inc ) The model input parameters used in the <br /> analysis are as follows <br /> Hydraulic conductivity = 60 ft/day <br /> Hydraulic gradient = 0 002 <br /> Aquifer thickness = 23 feet <br /> Average flow direction = N45E <br /> These parameters have been previously reported in quarterly reports and in the <br /> "Supplemental Site Investigation Report," dated March 5 1991, (BCC) for this site <br /> The extraction system is not expected to have a significant impact on the regional hydraulic <br /> gradient <br /> Groundwater Treatment <br /> All extraction wells will be plumbed to the treatment area by PVC piping placed below <br /> ground Extracted groundwater will be treated by three 1,000-pound GAC units connected in <br /> series, located in the treatment area as shown on Figure 2 <br /> Discharge and Permits <br /> Treated groundwater is proposed to be discharged into the City of Tracy (City) storm drain <br /> system Piping from the treatment area to this storm dram located on Tracy Boulevard will be <br /> installed underground, as shown on Figure 2 <br /> Discharge will be regulated under a NPDES permit The NPDES permit application was <br /> submitted to the California Regional Water Quality Control Board (Regional Board) in <br /> February 1992 Permits for discharge will be obtained from the City of Tracy prior to any <br /> discharge If groundwater extraction is not needed, these permits will not be obtained <br /> Remediation Monitoring <br /> The efficiency of vapor extraction and treatment will be determined by periodic sampling <br /> of vapor from the wells, and at the mlet and outlets to the catalytic oxidizer Sampling times and <br /> intervals will be specified in the San Joaquin County Valley Unified Air Pollution Control <br /> District permit issued for this site <br /> The efficiency of the spargmg and groundwater extraction and treatment system, if needed, <br /> will be determined from groundwater samples collected quarterly from monitoring wells ATR-1, <br /> ATR-2, ATR-3, ATR-4, ATR-5, ATR-7, and ATR-8, and depth to groundwater data collected <br /> quarterly from all monitoring wells <br /> 7403,REPORTS%RENfHDATN PLN <br />