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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0219 -10- FOR COUNTY OF SAN JOAQUIN FOR CONSTRUCTION AND OPERATION OF NORTH COUNTY RECYCLING CENTER AND SANITARY LANDFILL FACILITY, SAN JOAQUIN COUNTY 54. The Discharger adequately demonstrated that construction of a Subtitle D prescriptive standard liner would be unreasonable and unnecessarily burdensome when compared to the proposed engineered alternative design. There is no clay source on-site and the cost of importing clay from off-site or mixing on-site soils with bentonite would cost substantially more than the alternative design. The Discharger has demonstrated that the proposed engineered alternative is consistent with the performance goals of the prescriptive standard and affords equivalent protection against water quality impairment. 55. The leachate collection and removal system collection components consist of(from top to bottom): • 2-foot-thick soil operations layer a 8-oz/sy nonwoven geotextile separator/filter a 0.75-foot-thick gravel drainage layer on base areas, and a geocomposite drain on the side slopes a Leachate collection troughs with 4- and 6-inch-diameter lateral and header piping surrounded with drainage gravel Each lateral leachate pipe is equipped with a pipe riser at each end for annual inspection, and cleaning if necessary. A wire rope will be installed in each leachate lateral pipe to enable pull through a video camera annually for LCRS inspection. All lateral and header leachate pipes are sized for flow capacities at least twice peak design flows from modeled"worst case"peak leachate production. The peak monthly leachate production,based on leachate removal records at the site;is less than 200,000 gallons per month. A 4-foot deep leachate removal sump allows for a 3-foot depth of leachate over a 2-foot deep monitoring trench,without leachate backup into the LCRS collection troughs. Leachate pipe riser is provided for the leachate monitoring and removal system. The leachate pump removal system includes leachate level monitoring sensors,pump, automatic pump controls, and a flow system to record leachate volumes removed. An existing above ground leachate storage tank will be used to receive leachate pumped from the sump, in advance of leachate handling for disposal. 56. The sump area is underlain with a secondary composite liner system, equipped with a monitoring and removal system to provide additional protection against the higher leachate head necessary within the leachate sump area. The system is designed to remove, far in excess of estimated leachate flows,to preclude leachate head build-up on the baseliner beyond the limits of the sump. A monitoring riser 12 inches in diameter is provided to enable monitoring for leachate, and its removal, if present.