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• Draft Supplemental Environmental Impact Report Page III-30 • Forward Inc.Landfill 2018 Expansion Project the pipes. The drainage layer is separated from the operations layer above by a nonwoven • geotextile to prevent migration of fine-grained material into the LCRS. • The LCRS design for slopes greater than 15 percent consists of a geocomposite drainage net (GDN). GDN is used due to construction and stability concerns associated with placement of • granular materials on steep slopes. No collection pipes are required on the side slopes because any . leachate occurring on the slope would naturally flow down slope. Leachate collected in the LCRS would flow through the drainage layer to the pipes and subsequently into leachate collection sumps. Submersible pumps located in each sump would ' pump leachate from the LCRS to lined surface ponds, from which the leachate evaporates. • Three leachate evaporation impoundments are permitted at the site, of which two are constructed and are currently in use. WMU F North is located in the southwest region of the existing Forward • Landfill,just north of the South Fork. It was constructed in 1999 and provides containment for . leachate from the active portions of the southern WMUs. The leachate impoundment was sized based on actual leachate generation records from 1991 to 1997 and has a design capacity of approximately 3.5 million gallons. WMU F West is located in the northern portion of the site, directly west of WMU FU-03. It was constructed in 2003 with a design capacity of 3.4 million • gallons and receives leachate from the northern waste management units. A third impoundment, WMU F South,has not yet been constructed as no waste has yet been landfilled south of the South Fork. WMU F South would replace the existing WMU F North leachate impoundment. If, during the service life of the landfill,the demand on the leachate impoundment exceeds capacity,Forward would implement an alternative leachate management plan. Leachate in excess of the impoundment's capacity would either be pumped to temporary onsite tanks,trucked for off- site disposal at the City of Stockton Municipal Utility Department wastewater treatment plant located at 2500 North Navy Drive in Stockton,or trucked to another off-site licensed Treatment • and Disposal Facility. Leachate stored in the temporary on-site tanks may be released back into the • impoundment at a later date. Leachate Monitoring • To monitor the LCRSs,Forward,Inc.conducts a leachate monitoring and sampling program in compliance with WDR Order No. R5-2014-0006. Quarterly and annual reports of the monitoring results are submitted to the DTSC,RWQCB,and the San Joaquin County Environmental Health • Department, which is the Local Enforcement Agency(LEA). • A leak detection system is also located under the sumps in the WMUs and the leachate impoundments. The leak detection system currently consists of suction cup lysimeters and pan lysimeters installed in all the Subtitle D lined WMUs with permanent sumps(i.e.WMU D-93,D-01, i D-02,FU-03,FU-04, FU-05, and FU-06). A suction lysimeter is a device that measures the soil pore • water in the unsaturated zone, while a pan lysimeter measures the water that percolates down from below the sump. The lysimeters are sampled and tested in accordance with the site's WDRs. The former Austin Road Landfill unit has no leachate collection system and therefore no lysimeters. .