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Mr. Sheldon Heckman, c/o Ms. Kama E. Herrigfeld - 2 - 15 September 2003 <br />Herurn Crabtree Brown, Stockton <br />periodically updated with new information from future investigations and groundwater monitoring. Please <br />provide a draft SCM by 15 November 2003. <br />The RCP Workplan proposes soil excavation in the USTs source area. I agree that the USTs source area should <br />to be remediated, but believe the soil vapor extraction (SVE) proposed in the Connell CAP by AGE for the <br />TPHss spill would, if expanded across the entire site, provide a more comprehensive approach for soil <br />remediation, without risking damage to the existing warehouse building. The proposed soil removal action is not <br />feasible, due to the proximity of the USTs area to the building, and the depth (over 50 feet bgs) of contamination <br />in the unsaturated zone. By 15 November 2003, provide a revised Interim Remedial Workplan based on the <br />Connell CAP, which uses SVE as an Interim Remedial Action for the entire site. <br />I believe that dual phase extraction could provide adequate dewatering to enhance the effect of the Interim SVE <br />proposed by AGE in the CAP, but caution that other technologies need to be evaluated to remediate the deeper <br />1,2-DCA groundwater plume. I recommend that AGE and FE coordinate their input into a comprehensive CAP <br />which will evaluate the feasibility of the following options and provide a Final Remediation Plan for one or more <br />technologies, including: additional soil removal based on an soils engineering study, dual-phase extraction for <br />enhanced SVE and shallow groundwater contamination, and air sparging (AS) or other technologies for deeper <br />groundwater contamination. I suggest that you evaluate at least two methods of disposal for treated groundwater: <br />discharge under local permit to the City of Stockton sewers, or discharge of treated groundwater to an infiltration <br />trench constructed onsite and downgradient of the groundwater plume. The infiltration trench discharge option <br />will require a completed application and Report of Waste Discharge (ROWD) for Waste Discharge Requirements <br />(WDRs) for land disposal from the Regional Board. Therefore, a revised CAP, which targets comprehensive <br />remediation for the entire site, soil and groundwater, is necessary and required by 15 December 2003. <br />The 1,2-DCA investigation needs to be expanded to characterize the lateral extent of the 1,2-DCA groundwater <br />plume to the north and west of the USTs source area and the vertical extent across the site. A new workplan <br />needs to identify data gaps in the initial investigation, and propose additional CPT sampling points and <br />monitoring well locations. Provide an Additional 1,2-DCA Investigation Workplan by 15 November 2003. You <br />may combine this investigative worlcplan with the revised Interim Remedial Workplan and the SCM. <br />Please continue to copy all correspondence and documents to Mr. Mike Infurna, SJCEHD, and provide me with <br />at least 72 hours of notice prior to commencing fieldwork. If you have any questions please contact me at (916) <br />255-3050 or bartonj (rb5s swrcb . ca. gov. <br />James L. Barton, R.G. <br />Engineering Geologist <br />cc: Mr. Michael Infurna, San Joaquin County Environmental Health Services, Stockton <br />Mr. Richard Calone, Esq., Stockton <br />Mr. William Little, Advanced GeoEnvironmental, Stockton <br />Mr. Erv Riffenburg, Foothills Engineering, Lodi