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Leachate System Monitoring and Maintenance The flow rate provided by the sump pump is tested at least monthly. If no other causes are apparent, a decrease in pumping rate will indicate the need to clean a filter or to investigate pump wear. Leachate production rate is greater in the late winter and spring, compared to summer and autumn,because little or no rain falls on the site from April to November of each year. The secondary leachate sump is monitored monthly for the presence of LFG condensate. If possible,this condensate is removed, and if removed,the volume is recorded. Landfill Gas Condensate Removal from Module 1 Secondary Sump Investigations by the County indicated that the landfill gas condensate accidentally delivered to the secondary sump of Module 1 was forced into the anchor trench a few feet below the ground surface along the edge of the secondary sump liner. Removal of LFG condensate remaining in the secondary sump began in April 2009, and now continues monthly concurrent with landfill inspection. Monitoring of condensate removal includes measuring the depth of condensate in the secondary sump before and after pumping, and measuring the volume of condensate withdrawn during pumping. The depth of condensate in the secondary sump is measured by a bubbler tube installed into the sump. Condensate is removed from the secondary sump by a centrifugal pump installed in the sump. The volume of condensate removed is measured by measuring the time of pumping,having establishing that the pumping rate is 10 gallons per minute. The pump is allowed to run until lack of liquid causes the pump safety features to stop the pump. Liquid removed from the secondary sump is delivered to the landfill surface over the lined area of Module 1. After the initial removal event of mid April,withdrawal of condensate continues to decrease from an initial 27 gallons per day in late April to approximately 0.3 gallons per day. However,this collection rate remained constant, rather than decreasing as expected. This observation,together with observations during a high- level event in the primary sump in March 2011 indicates a hydraulic connection between the primary and secondary sump. The County has proposed to install permanent pumping capability in the secondary sump to ensure that the hydraulic head in the secondary sump does not exceed 12 inches. HISTORICAL TIME SERIES PLOTS Constituents not detected are plotted at a value of half their respective detection limits in the Historical Time Series Plots (Appendix F). Outliers were included in the plots as directed by RWQCB staff. PROGRESS OF EVAPOTRANSPIRATION COVER The purpose of the evapotranspiration cover is to capture rain water during the wet months, allowing the vegetation growing on that cover to remove the water from the soil during the dry months,restoring the storage capacity of the soil for the next rainy season. Providing storage for rainwater each year prevents the percolation of water into the refuse. The intention of this closure method is to minimize water percolating into the refuse at least as effectively as the prescriptive barrier layer(one foot thick with permeability of 10-6 cm/sec or less). Foothill Sanitary Landfill 12 Department of Public Works/Solid Waste I"Semester 2011 Groundwater Monitoring County of San Joaquin—July 31,2011