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Draft Environmental p Impact Report Page IV.F-14 Forward Inc. Landfill Expansion F A corrective action program (CAP)was proposed in 1991 to address the impact of chlorinated hydrocarbons to groundwater. The plan was approved by the RWQCB in June 1991 and involves the following actions: Reduction of leaching of chlorinated hydrocarbons into the groundwater by F checking incoming loads into the landfill for hazardous materials and implementing measures to reduce storm-water.infiltration into the refuse; F4 • Extraction of groundwater from two wells to reduce the off-site migration of chlorinated hydrocarbons; • Installation of an above-ground treatment system to remove VOCs from the F.; extracted groundwater prior to discharge; and • Monitoring the effectiveness of the c6rrective action and determination of the need F for modifications. i j This initial CAP has been followed with augmentation in 2001,when the Austin Landfill unit was added. In order to better understand the dimensions and impacts of the plume,the RWQCB ordered further investigations to be conducted. In January 1999,Camp Dresser&McKee(CDM) prepared the"Austin Road Landfill Contaminant Plume Report" and the "Groundwater Corrective Action Feasibility Study Report". Following the implementation of the report recommendations,various investigations,evaluations and quarterly and annual reporting to the a RWQCB has occurred (summarized in the JTD,2007) up through the most recent report on the downgradient well monitoring plan(HA,2009). A draft new CAP is currently under review by the RWQCB(D.Hershfield, verbal communication,2009) The VOC contaminant plume was estimated to extend approximately 5,500 feet from the northern F border,based on the detections at the downgradient Northern California Youth Correctional Center (NCYCC)well CYA-1. The NCYCC uses one well(CYA-4)for its water supply and has two additional wells for standby emergency (CYA-2) and backup water supply(CYA-1).The plume appears to have migrated to a lower depth at the leading edge of the plume,which is fairly typical in such subsurface materials. The primary contaminants of concern are PCE and TCE with the highest VOC concentrations present within a sand layer that extends over an interval of approximately 80 to 104 feet below ground surface(bgs). The investigation results indicate that contaminant concentrations decrease at distances from the source, with the plume migrating in deeper lithologic units at a distance from the site. The plume shape reflects the north to northeast groundwater flow direction,with the leading edge of the plume extending east of Austin Road. The contaminant plume is moving at a relatively rapid rate,approximately 4 feet per day, (1,460 feet per year). This suggests that VOC migration rates are not affected significantly by sorption of contaminants to aquifer materials. The trend of reduced contaminant concentrations away from the landfill is attributed primarily to dilution occurring through mixing with unimpacted groundwater and with surface water recharge. FIn 2008 detections of VOCs above drinking water MCLS at the Northern California Youth Correctional Center(NCYCC)wells were reported. This resulted in the RWQCB Order(2008-0712) requesting Forward landfill to complete a Water Supply contingency plan(WSCC)for the NCYCC. F This WSCC was completed (HA,2008)and suggested that the problem would be solved in about 6 months by piping municipal water to the NCYCC,which Forward would facilitate. Prior to bringing in municipal water the short-term solution recommended was to either blend the water F.