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Operation of the pump is conditional upon sufficient water in the sump and available capacity in the leachate ® tank. A high level alarm is activated if the leachate exceeds the alarm level. The alarm level is chosen to maintain the hydraulic head on the Area base below the maximum allowed 12 inches. The leachate storage tank facility includes secondary containment(consisting of a concrete vault surrounding the tank) and a truck loading area. Controls for the leachate storage tank include a high level sensor that will sound an alarm and disable the leachate sump pump if the level in the tank nears the top of the tank. This prevents overtopping of the tank. However,the secondary containment will retain any leachate in case of failure of those controls. Leachate System Monitoring and Maintenance The flow rate provided by the sump pump is tested at least monthly. If no other causes are apparent, then 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 removal of LFG condensate Landfill Gas Condensate Removal from Area 1 Secondary Sump The pump permanently installed in the secondary sump under Area 1 operates once three days per week, pumping liquid, if any, from the secondary sump into the primary sump. Once started, the pump operates until pump protection circuits stop pumping due to insufficient liquid. A meter is provided to monitor the liquid removed. The depth of liquid in the secondary sump is also monitored monthly using by a bubbler tube installed into the sump. Measurements indicate that the pump is maintaining the liquid level at the minimum level that allows the pump to remove liquid. HISTORICAL TIME SERIES PLOTS Historical Time Series Plots are included with this report on CD. Note that constituents that are not detected are plotted at a value of half their respective detection limits. Outliers were included in all 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). A key component of this method is the vegetation on the cover. Perennial plants, such as purple needle grass and California Brome, send roots deep within the soil to gather moisture, providing storage capacity during Foothill Sanitary Landfill 11 Department of Public Works/Solid Waste 1 s'Semester 2013 Groundwater Monitoring County of San Joaquin—July 25,2013