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Ij '.•s EDMUND G. BROWN JR. <br /> 2i _' GOVERNOR <br /> op <br /> G®L I F O W W I® MATTHEW RODRIQUEZ <br /> SECRETARY FOP <br /> ENVIRONMENTAL PROTECTION <br /> Water Boards <br /> Central Valley Regional Water Quality Control Board <br /> RECEIVED <br /> 16 January 2015 <br /> JAN 2 2 2015 <br /> ENVIRONMENTAL H LT <br /> Mr. Taj M. Bahadori, PE <br /> IT/SE VIrES <br /> Senior Civil Engineer <br /> San Joaquin County Public Works, Solid Waste Division <br /> 1810 E. Hazelton Avenue <br /> Stockton, CA 95201 <br /> REVISED WORK PLAN FOR INSTALLATION OF GROUNDWATER WELL MW-6, FOOTHILL <br /> SANITARY LANDFILL, SAN JOAQUIN COUNTY <br /> The Foothill Sanitary Landfill is owned by San Joaquin County Department of Public Works and <br /> operated by Foothill Landfill Inc. (hereinafter jointly known as Discharger) and is regulated by <br /> Waste Discharge Requirements Order R5-2003-0020 and Cleanup and Abatement Order <br /> R5-2004-0706. Central Valley Water Board staff issued a Notice of Violation (NOV) to submit a <br /> work plan to install an additional groundwater monitoring well south of future Module 2. A work <br /> plan was submitted describing the new well to be installed in similar fashion as well MW-5; <br /> located approximately 1,000 feet west of the proposed MW-6 location. <br /> In a letter dated 30September 2014 staff provided approval of the well location and well design. <br /> However, in an email dated 20 November 2014, the Discharger submitted a revised well design <br /> based on a concern that groundwater levels beneath the Foothill site are decreasing. In an <br /> email dated 25 November 2014 staff requested a revised work plan and additional groundwater <br /> information including expected decrease of groundwater levels annually. In an email dated 24 <br /> December 2014, the Discharger submitted a revised work plan as requested. <br /> Staff has reviewed the revised work plan and the rational supporting the request to construct <br /> well MW-6 with an upper and lower screen interval. This well will be located at the southern <br /> boundary of proposed Module 2 and will serve as a down gradient point of compliance well for <br /> the detection monitoring program. The Discharger agrees with this location and the intended <br /> use of the proposed well. The Discharger's rational for proposing a multi-screened well <br /> separated by an inflatable packer is to prolong the life of the well and the likelihood of having to <br /> re-drill wells as groundwater levels decrease. <br /> Staff's review of the historical groundwater data presented in the work plan for site wells <br /> MW-1/1A, MW-2/2R, MW-3, MW-4, and MW-5 indicates that groundwater levels are decreasing <br /> at a rate ranging between 0.35 feet/year (MW-3) to 0.70 feet/year (MW-4). Staff has reviewed <br /> the well details for the site wells and wells MW-1A and MW-3 were constructed with 20 feet of <br /> screen. Well MW-2R was constructed with 40 feet of well screen. Construction details for wells <br /> MW-4 and MW-5 were not available on Geotracker, but staff will assume 20 feet of well screen. <br /> The calculated groundwater decrease in each well per year and expected length of service of <br /> each well is projected below. <br /> KARL E. LONGLEY SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OEPICER <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 85670 1 www.waterboards.ca.gov/centraivalley <br /> `?RECYCLED PAPER <br />