ARCHIVED REPORTS_2012_4 - Laserfiche WebLink

Home Browse Search

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. ANNUAL SUMMARY Groundwater General Water Quality Parameters MW-4 was located directly up-gradient of the landfill based on groundwater elevations from the previously- installed wells. This well has been sampled fourteen times since installation. Concentration limits have been established based on Sanitas software calculations using data for MW-4. The following annual compliance review was prepared for each well: • Well MW-1:No General water quality parameters were exceeded during the 1St semester 2012 sampling event. EC was recorded at 764.3 uS/cm which slightly exceeded the tolerance limit of 710 uS/cm during the 2nd Semester 2012 sampling event. However, MW-1 is not downgradient from the landfill and this level of detection of EC at this time in this well is not an indication of landfill impact to groundwater. • Well MW-2R: No General water quality parameters were exceeded during the 1st and 2nd semester 2012 sampling events. Foothill Sanitary Landfill 11 Department of Public Works/Solid Waste 2nd Semester and Annual 2012 Groundwater Monitoring County of San Joaquin—January 15,2013