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OAC.0(N C <br /> OP.O.BOX 1810-1810 E.HAZELTON AVENUE <br /> THOMAS M.GAU STOCKTON,CALIFORNIA 95201 <br /> DIRECTOR <br /> (209)468-3000 FAX(209)468-2999 <br /> •��C,foR ;P, www.sjgov.org/pubworks <br /> MICHAEL SELLING _ - s <br /> DEPUTY DIRECTOR �'�i•1 P - -� - _. __ <br /> STEVEN WINKLER <br /> DEPUTY DIRECTOR <br /> ROGER JANES <br /> BUSINESS ADMINISTRATOR <br /> June 3, 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- INCREASE IN CORRECTIVE ACTION AND OTHER ISSUES, <br /> FOOTHILL SANITARY LANDFILL <br /> Dear Mr. Del Frate: <br /> This letter is follow-up to our conversation last week regarding two recent developments at the <br /> Foothill Sanitary Landfill. <br /> The first development is the reoccurrence of low concentrations of two compounds at <br /> groundwater monitoring well MW-3 (Figure 1). These compounds are dichloroethene at 0.6 ppb <br /> and trichloroethene at 1.2 ppb in our most recent analysis. These compounds were last found <br /> at this well in 2002, and are presumed to originate in landfill gas (LFG). All other groundwater <br /> monitoring wells are impact-free. <br /> To address this issue, we intend to increase corrective action in accordance with Title 27 <br /> Section 20430 (i). This increase in corrective action includes increasing the effectiveness of the <br /> LFG collection system in that portion of the landfill. Specifically, we would: <br /> • Replace LFG extraction well GX-2. The lateral to the existing well is apparently blocked <br /> with LFG condensate, but is not accessible because it is beneath the <br /> Module "I"/Module 1 liner. Therefore we will drill a replacement well GX-2A near the <br /> existing well, but outside the liner, and re-establish LFG collection from that area. <br /> • Increase LFG collection from wells GX-7 and -9 by replacing the 3" laterals now in place <br /> with 6" and 4" pipe. These two wells are closest to MW-3. <br /> We are evaluating the timeline to assess what might have caused this re-emergence. After we <br /> corrected our ponding problem in the winter of 1997/98, and after the resulting impact subsided <br /> in February 2002, we were impact-free without a LFG system. We remained without impact <br /> through the installation of a LFG system and installation of liner over Module "I" refuse in 2006 <br /> and until the first quarter 2011. <br />