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California 10gional Water Quality Co4pol Board 6!u �ahP Q Central Valley Region Katherine Hart, Chair F PP 11020 Sun Center Drive,#200, Rancho Cordova,California 95670-6114 Linda S.Adams (916)464-3291 - FAX(916)464-4645 Edmund G.Brown Jr. Acting Secretary for http://www.waterboards.ca.gov/centralvalley Governor Environmental Protection EC 21 June 2011 JUN 11 W. Michael Carroll ENVIRONMENTAL HEALTH San Joaquin County Dept. of Public Works PERMIT(SERVICES Solid Waste Division P.O. Box 1810 Stockton, CA 95201 INCREASE IN CORRECTIVE ACTION FOR FOOTHILL SANITARY LANDFILL, SAN JOAQUIN COUNTY Staff of the Central Valley Water Board has reviewed the letter dated 3 June 2011 proposing to increase corrective action as a response to detections of volatile organic compounds (VOCs) in groundwater collected from well MW-3 at the Foothill Sanitary Landfill. VOC detections were last reported in well MW-3 during 2002 and were eliminated after previous corrective action was performed. The current VOCs detected in well MW-3 were detected in 2002 and are thought to be originating from landfill gas. All other groundwater wells are free of VOCs. To address the impacts at well MW-3, the Discharger proposes to increase corrective action in accordance with Title 27 20430 (i). The proposed corrective action includes increasing the effectiveness of the LFG collection system. Specifically, the Discharger will replace well GX-2 with a new LFG extraction well to be located outside of the lined side slope of Module 1. GX-2 is being replaced because the lateral piping to the well is blocked with LFG condensate, which is not accessible for repair since it is located underneath the side slope liner. This will reestablish LFG collection in this area. The Discharger will also replace existing three inch diameter piping with four and six inch piping that will enhance collection from wells GX-7 and GX-9, which are closest to well MW-3. The Discharger also reports that it is recovering liquid in the secondary sump beneath the primary liner of Module 1. Liquid has been continuously pumped at low volumes from the secondary sump since April 2009 when the landfill operator discovered that LFG condensate was plumbed into this sump. The Discharger has determined that a hydraulic connection exists between the primary and secondary sumps. However, the liner over this portion of the landfill is buried approximately 30 feet below refuse and is not accessible for repair. To keep liquid from collecting in the secondary sump the Discharger proposes to install a permanent, automated pump in the secondary sump. The pump will be adjusted to keep the liquid in the sump from exceeding 12 inches. The liquid withdrawn will be plumbed into the primary sump. California Environmental Protection Agency �aRecycled Paper I