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THOMAS M.GAU P.O.BOX 1810-1810 E.HAZELTON AVENUE <br /> DIRECTOR STOCKTON,CALIFORNIA 95201 <br /> 49N% (209)468-3000 FAX(209)468-2999 <br /> mw,sjgov.org/pubworks <br /> FRITZ BUCHMAN <br /> DEPUTY DIRECTOR wp7]dng for You <br /> MICHAEL SELLING <br /> DEPUTY DIRECTOR <br /> JIM STONE <br /> DEPUTY DIRECTOR <br /> ROGER JANES <br /> BUSINESS ADMINISTRATOR <br /> July 31, 2014 <br /> Mr. Todd Del Frate, PG <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> ' 11020 Sun Center Drive, #200 <br /> Rancho Cordova, California 95670-6114 <br /> 1 SUBJECT: FIRST SEMIANNUAL 2014 GROUNDWATER AND SURFACE WATER <br /> MONITORING REPORT; FOOTHILL SANITARY LANDFILL <br /> ' Dear Mr. Del Frate: <br /> Enclosed is the First Semiannual 2014 Groundwater and Surface Water Monitoring Report for <br /> the Foothill Sanitary Landfill, submitted in accordance with Waste Discharge Requirements <br /> R5-2003-0020. <br /> Groundwater monitoring results indicate that concentration limits were slightly exceeded at well <br /> MW-1A where concentrations of sodium (18 ppm), chloride (11 ppm), and sulfate (13 ppm) were <br /> reported. However, since MW-1A represents background conditions these slight exceedances <br /> are due the changes in the regional groundwater conditions and not likely due to landfill <br /> impact. In addition, concentration limits for chloride were also slightly exceeded in MW-3 (8.6 <br /> ppm) and MW-5 (8.8 ppm). However, these low concentrations are within the range of historical <br /> data and would be considered a good source of drinking water. Reporting exceedances at <br /> these low concentrations is a product of the statistical analysis software and not likely due to <br /> landfill impact. <br /> Two (2) VOCs, not exceeding 1.4 ppb, were reported in well MW-3. No VOCs were detected in <br /> MW-3 during the last Semiannual Monitoring Period. VOCs have been sporadically detected in <br /> MW-3 since 2010. The County believes that the impermeable membrane placed over refuse on <br /> IArea "I" in 2006 may be contributing to this effect. <br /> The County continues to be concerned that placing an impermeable membrane over refuse of <br /> an unlined landfill promotes movement of landfill gas (LFG) towards the groundwater, and that <br /> this effect cannot entirely be countered by a LFG collection system. The enclosed report <br /> includes a detailed review of monitoring data at MW-3. <br /> tSurface water and storm water samples were not available this period due to lack of rainfall. <br />