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Mr. Joel Weiss <br /> April 22, 1996 <br /> Page 2 <br /> presently stockpiled on site (estimated at 25,000 tons or 15,600 cubic yards [cy]) will be <br /> treated to immobilize the lead. Treatment will be by a proprietary process offered by <br /> Cunningham Davis Environmental, Inc. Treated soil will be sampled and analyzed for <br /> soluble lead using the WET with both a citrate and a deionized water leach. Approximately <br /> 25 samples of treated soil will be collected and analyzed by both methods (one sample per <br /> 1,000 tons or 625 cy). Remediation goals for treated soil are 5.0 mg/L or less of lead by <br /> WET with citrate leach (California soluble threshold limit concentration [STLC] for lead) and <br /> 0.1 mg/L or less of lead by WET with deionized water leach (Regional Board criteria based <br /> on Designated Level Methodology). <br /> All treated soil that meets the above criteria will be placed in the bottom portion of the <br /> excavated areas on site and compacted. Clean and geotechnically suitable soil will be <br /> imported, placed and compacted over the treated soil. It is estimated that from 1 to 2 feet of <br /> clean, imported soil will overlay the treated soil in all areas. <br /> Following completion of remediation field activities, four temporary monitoring wells will be <br /> installed at the approximate locations indicated on the attachment to the February 15, 1996 <br /> letter. The elevation of the new monitoring wells and the two existing monitoring wells will <br /> be surveyed. Quarterly monitoring of all six wells will begin as soon as surveying is <br /> complete. Monitoring will consist of measurement of depth to water and collection of <br /> ground water samples which will be analyzed for dissolved lead. A minimum of three <br /> quarters of monitoring will be conducted. Quarterly monitoring reports in letter form will be <br /> submitted to the Regional Board. <br /> Schedule <br /> Based on equipment availability and status of permitting, it is anticipated that the treatment <br /> unit will be on site by May 1, 1996. Approximately one week will be required for site <br /> preparation including debris removal. Approximately 30 working days or six weeks will be <br /> required for screening and treating of all stockpiled soil and sampling/analysis of the treated <br /> soil. Backfilling will begin as soon as analytical results are received for the initial treated <br /> soil. Demobilization of the treatment unit and completion of backfilling and compaction <br /> (treated and imported soil) will require an additional five working days. The total estimated <br /> duration of site activities is eight weeks. Assuming a May 1, 1996 starting date, site <br /> activities should be completed by the end of June 1996. An additional six weeks will be <br /> required for preparation and SPTCo review of a final remediation report. The projected date <br /> for submittal of the final remediation report to the Regional Board is August 9, 1996. <br /> 4h9-024.1tr 04-"-96 u kevdataloldtracyl letters <br /> TerraNext <br />