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I <br /> O'ARR ASSOCIATES <br /> Environmental Engineering and Geohydrology <br /> August 8, 2006 2006 AUG 21 AM 11= 42 <br /> SAN joAQUIN <br /> ENVIRONMENTATY <br /> L <br /> HEALTH DEPARTMENT <br /> Mr. Mark Adams, Trustee <br /> Lincoln Center Environmental Remediation Trust <br /> 137 Park Place <br /> Richmond, CA 94801 <br /> Subject: LPL Comments on LFR's Proposed Phase IV Interim Remedial Action Detailed <br /> Plan for the Lincoln Center Site, Stockton, California <br /> Dear Mr. Adams: <br /> On behalf of Lincoln Properties Ltd. (LPL), Farr Associates submits this comment letter on the <br /> Phase IV Interim Remedial Action Detailed Plan (Phase IV IRA Plan) for Lincoln Center, <br /> Stockton (the Site), which was prepared by LFR on behalf of the Lincoln Center Environmental <br /> Remediation Trust (LCERT). Some of the comments discussed in this letter were verbally <br /> conveyed to you during our meeting at Lincoln Center on July 12, 2006. The Phase IV IRA Plan <br /> is well written, and presents the results of the recent Membrane Interface Probe (MIP) <br /> investigation and the plans for the Phase IV IRA clearly and concisely. LPL appreciates <br /> LCERT's work, and we look forward to implementation of the Phase IV IRA. LPL concurs <br /> generally with LCERT's plans for the Phase IV IRA, and the comments we present here are <br /> aimed toward increasing the effectiveness and efficiency of the Phase IV IRA. The increased <br /> effectiveness and efficiency will reduce long-term costs and speed the completion of Site <br /> remediation. <br /> The recently collected MIP data, along with the previously collected CPT sample data, are very <br /> useful in defining the volume of subsurface sediments to be targeted for remediation with the <br /> proposed air/ozone sparging system. We applaud LFR for extending the previous boundaries of <br /> the "Historical Source Area" eastward and to the north of Benjamin Holt Drive to reflect a larger <br /> source area, as indicated directly by the MIP and CPT data. However, the MIP and CPT data, <br /> and the other data from previous Site investigations indicate that the Historical Source Area is <br /> still larger than the area encompassed by LFR's new extended boundaries. The expanded target <br /> source area for air/ozone sparging should also include the area beneath Benjamin Holt Drive, in <br /> the gap between the three currently defined source areas where air/ozone sparging points are <br /> proposed in the Phase IV IRA Plan. LPL therefore requests that LCERT install and operate <br /> additional air-sparging points, to be located beneath Benjamin Holt Drive to the east of the <br /> sparging points already proposed for the treatment of saturated-zone sediments beneath Benjamin <br /> Holt Drive. The presence of extremely thick asphalt paving on Benjamin Holt Drive should <br /> provide adequate lateral soil-gas containment and allow the air/ozone injected beneath the <br /> roadway to be effectively captured using the existing soil-vapor extraction (SVE) wells north and <br /> south of the roadway. <br /> 6016 Princeton Reach Way • Granite Bay,California 95746 Tel. (916) 781-9327 • Fax (916) 781-9357 <br />