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Y California. eional Water Quality Col Board <br /> ® Central Valley Regions <br /> Karl E.Longley,ScD,P.E.,Chair M` <br /> Linda S.Adams Arnold <br /> Secreraryfor 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Schwarzenegger <br /> F e rronmenral Phone(916)464-3291 •FAX(916)464-4645 Governor <br /> Prronme n http://www.waterboards.ca.gov/centraivalIcy <br /> NrRgSVED <br /> 12 October 2009 T 14 2009 <br /> ENVIRONMENT HEALTH <br /> W. Michael Carroll PERMIT/SERVICES <br /> San Joaquin County Dept. of Public Works <br /> Solid Waste Division <br /> P.O. Box 1810 <br /> Stockton, CA 95201 <br /> REVIEW OF FIRST AND SECOND QUARTER 2009 GROUNDWATER AND SURFACE <br /> WATER MONITORING REPORT, CORRAL HOLLOW SANITARY LANDFILL, SAN <br /> JOAQUIN COUNTY <br /> The Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br /> has reviewed the 1St and 2nd Quarter 2009 Groundwater and Surface Water Monitoring Report <br /> for the Corral Hollow Sanitary Landfill. The reports were prepared in accordance with <br /> Monitoring and Reporting Program No. 5-01-0176. Based on the past groundwater data from <br /> wells MW-5 and MW-8, it is evident that landfill gas (LFG) has impacted shallow groundwater. <br /> In a letter dated 11 April 2007, Board staff approved an Evaluation Monitoring Program (EMP) <br /> work plan to delineate the migrating LFG plume. In a letter dated 4 February 2008, staff <br /> agreed to delay the EMP investigation if the County installed additional corrective action LFG <br /> extraction wells in the vicinity of well MW-5 and the northeastern facility boundary. It is the <br /> understanding of staff that these corrective action extraction wells were installed during <br /> December 2008. <br /> Upon review of the 1St and 2nd Quarter 2009 groundwater sample results, volatile organic <br /> compounds (VOCs) continue to be detected in well MW-5 and newly installed well MW-8. <br /> Several constituents of concern including tetrachloroethene (PCE), trichloroethene (TCE), and <br /> vinyl chloride exceed not only the Public Health Goal limit but also the maximum contaminant <br /> level (MCL) established for drinking water. <br /> The 1s' and 2nd Quarter 2009 report indicates that concentrations of PCE, TCE, and <br /> cis-1,2-DCE are increasing within groundwater collected from well MW-5. This biodegradation <br /> series is also found in well MW-8, but chemical trends have not been established. Since the <br /> installation of the five additional LFG extraction wells in December 2008, groundwater in the <br /> vicinity of wells MW-5 and MW-8 is not showing any improvement in water quality, in fact, the <br /> increasing trends of PCE, TCE, and cis-1,2-DCE suggest otherwise. <br /> At this juncture, progress of corrective action measures taken do not appear to be effective in <br /> reducing concentrations of constituents of concern reported in groundwater. Staff <br /> CIWQS VID#841407 <br /> California Environmental Protection Agency <br /> ��Recycled Paper <br />