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THOMAS R. FLINN P.O.BOX 1810-1810 E.HAZELTON AVENUE <br /> DIRECTOR <br /> STOCKTON,CALIFORNIA 95201 <br /> I C&r (209)468-3000 FAX(209)468-2999 <br /> www.sjgov.org/pubworks <br /> 6*i' <br /> THOMAS M.GAU <br /> CHIEF DEPUTY DIRECTOR <br /> MANUEL SOLORIO Wcrldmg for YOU MC) FF- <br /> DEPUTY DIRECTOR H <br /> STEVEN WINKLER9 <br /> DEPUTY DIRECTOR JAN 1 5 Mi <br /> ROGER JANES January 12, 2009 <br /> BUSINESS ADMINISTRATOR ENVIRONMEIN I I'EALTH <br /> PERMIT/SERVICES <br /> Mr. Todd Del Frate <br /> California Regional Water Quality Control Board <br /> 11020 Sun Center Drive, # 200 <br /> Rancho Cordova, California 95670-6114 <br /> SUBJECT: INSTALLATION OF NEW LANDFILL GAS EXTRACTION WELLS <br /> AT CORRAL HOLLOW SANITARY LANDFILL <br /> Dear Mr. Del Frate: <br /> The County is pleased to inform you that the installation of additional Landfill Gas (LFG) <br /> extraction wells at the northeastern side of Corral Hollow Sanitary Landfill (CHSL) was <br /> completed on December 12, 2008. The purpose of the new LFG extraction wells is to help <br /> mitigate LFG's impact to the shallow aquifer by increasing LFG collection in the area. The <br /> project was completed in accordance with the design submitted to all regulating agencies. <br /> The County believes the installation of new LFG extraction wells will improve the quality of <br /> shallow aquifer groundwater. We hope to see this improvement in the third quarter of 2009. <br /> Five new LFG extraction wells were installed and connected to the existing LFG collection <br /> system (Figure 1 and 2). Of the five new LFG extraction wells, three wells, EW-40, EW-41 <br /> and EW-42, were installed near recently discovered pockets of refuse on CalTrans property <br /> (Figure 2). The other two new LFG extraction wells, EW-43 and EW-44, were installed within <br /> the footprint of the landfill near shallow aquifer ground water monitoring wells MW-4 and <br /> SBA (Figure 2). <br /> Installation of the new LFG extraction wells required disturbance to the closure cap barrier, <br /> layer at certain locations. The closure cap was fully restored. <br /> Barrier Layer Restoration <br /> 1. Well Boring Penetration of EW-43 and EW-44 LFG Extraction Wells <br /> Borings of LFG extraction wells EW-43 and EW-44 penetrated the closure cap barrier <br /> layer. The barrier layer disturbed by the well borings was restored by placing a <br /> Geosynthetic Clay Liner (GCL) surrounding the well's casing in an excavated six-foot <br /> wide square by eighteen inches deep pad. The edges of the GCL abutting the pad <br /> and the well casing were sealed with bentonite (Photo 1). The pad was then <br /> backfilled with moistened soil and compacted to the surrounding grade. <br />