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■ Return pump at Area 4 leachate tank to deliver leachate to a location other than a water truck, if needed. Although not yet needed, this pump would be used to deliver leachate to a Area with a Subtitle D-approved liner. Semi-permanent points of return of leachate to the refuse include three Deep Infusion Points ("dry" wells), all installed over Lined Area 3. The highest elevation of the base of Area 3 in this area is approximately 96 NGVD. The bottom of these Deep Infusion Points (DIPS) are approximately at elevation 140 ft NGVD. Approximately 50 feet of refuse in multiple lifts exists between the point of infusion and the base of the landfill. Construction and alteration of the DIPS was reported in detail in the First Semester 2005 Groundwater and Surface Water Monitoring Report. Leachate was not returned to DIPS in this monitoring period. 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 Lined Area 1 Pump On 45 48 High Level Alarm(2) 50 13 Pump Off 10 83 Lined Area 3 Pump On 75 78 High Level Alarm (2) 80 13 Pump Off 8 32 (3) Lined Area 4 Pump On 18 42 High Level Alarm (2) 24 48 Note 1:"Indicated depth"is the reading of depth from the sensor located on the pump,approximately three inches above the inner surface of the sump pipe at the location of 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 floor of the Lined Area beyond the sump. Note 3:The leachate pump intake of Lined Area 4 is located 24 inches above the floor of the sump to avoid pulling soil from sump into the pump. North County RC&SL Public Works/Solid Waste 2ntl Semester and Annual 2013 Groundwater Monitoring 14 County of San Joaquin—January 25,2014