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Additional infusion areas are constructed in Area 4 as needed to accept leachate. Normal Operation Leachate drains by gravity to the Area sumps from which it is pumped directly to the landfill refuse per the WDRs. The sump pump operates automatically, based on leachate levels within the sump. Operation of any Area sump pumps is conditional upon sufficient water in the sump (indicated by the level sensor on the pump) and available capacity in the associated leachate tank(indicated by the float switch in the tank). Control points for the pumps are: Control Action Indicated Depth Actual Depth inches (1) inches (1) Pump Off 10 53 Area 1 Pump On 45 48 High Level Alarm (2) 50 13 Pump Off 10 83 Area 3 Pump On 75 78 High Level Alarm(2) 80 13 Pump Off 8 32 (3) Area 4 Pum On 18 42 High Level Alarm (2) 24 48 Note 1:"Indicated depth"is the reading of depth from the sensor located on the sump,approximately three inches above the pump (also see Note 3). Note 2:The high-level sump alarm is set to alarm at the upper lip of the leachate sump,thus alerting the operators before the one-foot leachate limit is exceeded at the Area floor beyond the sump. Note 3: The leachate pump intake of Area 4 is located 24 inches above the floor of the sump to avoid pulling soil from sump into the pump. In this semester, leachate from all three Areas was returned directly to the refuse of at approximately 160 ft NGVD, over approximately 120 feet of refuse compacted in multiple lifts. Data indicates that the leachate is being absorbed by the dryer refuse, and is not recirculating. Overwhelming of the LCRS system due to excessive recirculation is not indicated. Such indication would include the inability of a leachate sump pump to empty the sump. This condition was observed once, in 2003,when Area 4 was first installed. At that time, significant areas of that Area was lacking refuse, allowing rain water to quickly reach the LCRS without the opportunity to be absorbed by refuse. This situation was corrected by relocating the infusion of leachate to an area that contained more dry refuse. • Overwhehning the capacity of the refuse to absorb leachate would be indicated by leachate seeps on the side of the fill in the vicinity of the infusion areas. This condition has not been observed. North County RC&SL Public Works/Solid Waste I�'Semester 2013 Groundwater Monitoring 12 County of San Joaquin—July 25,2013