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California Regional Water Quality C�trol Board <br /> Central Valley Region <br /> Robert Schneider Chair Arnold Schwarzenegger <br /> Terry Tamminen Sacramento Main office Governor <br /> Secretary forhttp <br /> Environmental Internet Address: #200/w Rancho <br /> Cordova, <br /> CA 95b <br /> Protection 11020 sun Center Drive Phone(916)464-329dova,CA 95670-6114 <br /> July 27, 2004 /� <br /> .9,? <br /> �vD <br /> pFq�T�F�'T �Oq <br /> Mr. Mark Adams <br /> Lincoln Center Environmental Remediation Trust <br /> Point Environmental <br /> 137 Park Place <br /> Richmond, CA 94801 <br /> DUAL PHASE EXTRA CTION PILOT STUDY WORK PLAN;LINCOLN CENTER;SAN <br /> JOAQUIN COUNTY <br /> Regional Water Quality Control Board (Regional Board) staff has reviewed the Lincoln Center <br /> Environmental Remediation Trust's (LCERT) submittal entitled "Pilot Study Work Plan for Dual Phase <br /> Extraction, Historical Source Area, Lincoln Center"prepared by LFR Levine-Fricke and dated June 25, <br /> 2004. <br /> Dual phase extraction(DPE) is a remedial method whereby groundwater is extracted at a rate high <br /> enough to lower the groundwater levels so that soil vapor extraction(SVE)may be applied to the <br /> dewatered sediments. To investigate the feasibility of applying DPE to the historical source area at the <br /> site, LCERT proposes to install two 6-inch diameter DPE wells. New conveyance pipelines will be <br /> installed to connect the DPE wells to the current groundwater and vapor treatment systems. Existing <br /> groundwater and soil vapor monitoring wells will be used for observation(see attached proposed system <br /> layout). Following the well installations, aquifer-pumping tests will be performed to determine their <br /> optimum pumping rates. After optimum pumping rates have been established and implemented, vacuum <br /> will be applied to the wells in a step-wise fashion starting at 50 inches of water and increased in <br /> increments of 25 inches of water until the blower capacity is maximized or a vacuum of 150 inches of <br /> water reached. <br /> Regional Board staff concurs with the plan, subject to the following comment. The plan states that the <br /> radius of influence (R01) of the DPE wells is"defined as the distance from the well at whick a vacuum <br /> of 0.1 inch is observed in a well screened in the resaturated zone". Vacuum response in MR observation <br /> well is not, by itself an indication of the appropriate ROI to be used for the design of an SVE system. <br /> Designs for SVE systems should be based upon soil permeability estimates so that vapor travel time and <br /> pore volume removal estimates over time and distance can be evaluated. This comment does not <br /> necessitate revision of the work plan but should be considered when preparing the pilot study report. <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />