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r <br /> PURPOSE <br /> The purpose of this Section is to document the progress of the corrective action measures at <br /> Harney Lane Sanitary Landfill. The success of corrective action is indicated by no further <br /> rdegradation of groundwater by VOCs. <br /> CORRECTIVE ACTION MEASURES <br /> Final Landfill Cover and Cover Maintenance <br /> The final landfill cover was proposed as a corrective action measure based on the understanding <br /> that precipitation was creating leachate that was possibly reaching the groundwater, as indicated <br /> by increasing trends in inorganic constituents and previous site investigations. <br /> 1 <br /> The effectiveness of the final landfill cover would be indicated by the lack of statistically <br /> increasing trends in all inorganic constituents, which would indicate that leachate is no longer <br /> migrating to groundwater. <br /> A subsurface investigation performed in 1991 revealed no evidence of standing leachate beneath <br /> the landfill (Solid Waste Water Quality Assessment Test, Kleinfelder, June 1991). However,moist <br /> soils were encountered within 10 feet of the landfill bottom. Soil samples were analyzed for <br /> VOCs, surrogates of metallic constituents,metals, and pH. No VOCs were detected in any of <br /> these samples. <br /> The closure of the landfill included placing a clay barrier layer as a component of the landfill <br /> cover. This is understood to be an effective measure to prevent water infiltration into the landfill <br /> and the resulting production of leachate. The integrity of the landfill cover is monitored by visual <br /> inspections for ponding and erosion and by surface emission scans of the landfill's top cover. <br /> rIn accordance with Rule 4642 of the San Joaquin Valley Unified Air Pollution Control District <br /> (APCD), the County regularly scans the top surface of the landfill for surface emissions. Surface <br /> scans are a means of checking the integrity of both the LFG collection system and the landfill <br /> cover. The most recent surface emissions scan (October 2005) did not find any locations with <br /> emissions in excess of the regulatory limit. <br /> 1 <br /> Harney Lane Sanitary Landfill 1_1 Department of Public Works/Solid Waste <br /> 1"Quarter 2007 Groundwater Monitoring Report County of San Joaquin—April 15,2007 <br />