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a . <br /> THOMAS M.GAU P.O.BOX 1810-1810 E.HAZELTON AVENUE <br /> DIRECTOR All STOCKTON,CALIFORNIA 95201 <br /> rib ap (209)468-3000 FAX(209)468-2999 <br /> www.sjgovorgipubworks <br /> t^ <br /> MICHAEL SELLING <br /> DEPUTYDIRECTOf2 <br /> STEVEN WINKLER <br /> DEPUTY DIRECTOR <br /> ROGER JANES <br /> BUSINESS ADMINISTRATOR <br /> July 22, 2011 <br /> Mr. Todd Del Frate <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 11020 Sun Center Drive, #200 <br /> Rancho Cordova, California 95670-6114 <br /> SUBJECT: FIRST SEMESTER 2011 GROUNDWATER AND SURFACE WATER <br /> MONITORING REPORT; FOOTHILL SANITARY LANDFILL <br /> Dear Mr. Del Frate: <br /> Enclosed is the First Semester 2011 Groundwater and Surface Water Monitoring Report for the <br /> Foothill Sanitary Landfill. Groundwater monitoring continues on a semi-annual basis in <br /> accordance with our WDRs. <br /> General parameters, minerals and inorganic results are unremarkable. <br /> The up-gradient Well MW-4 has been sampled eleven times since installation. This is sufficient <br /> for statistical analysis by Sanitas. <br /> Two VOCs (TCE and DCE) are found again at well MW-3 at concentrations below 2 ppb. The <br /> reoccurrence of these compounds after years of non-detection is troublesome, especially when <br /> many of those years were without a LFG collection system. The enclosed report includes a <br /> review of the timeline of events at this site in an attempt to discern the cause. <br /> The County continues to be concerned that placement of an impermeable liner over refuse <br /> restricts venting of LFG from the refuse, and that this restriction forces LFG into the groundwater <br /> in spite of the presence of a LFG collection system under the liner. <br /> Surface water from the creek on the eastern property boundary was sampled this year. Results <br /> were similar between the upstream and downstream samples, indicating no noticeable impact <br /> by surface flow from the landfill property. <br /> Vegetation on the evapotranspirative closure area was thick after the winter rains, and has been <br /> grazed twice this year. We believe that grazing assists the perennial grasses (with their deep <br /> roots) by removing the shade from the dead stalks of the annual plants. Photos are included. <br />