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• 7.0 DISPOSAL SITE CONTROLS <br /> 7.1 LEACHATE MANAGEMENT PLAN <br /> 7.1.1 LEACHATE COLLECTION AND REMOVAL SYSTEM <br /> The majority of the existing WMUs at the Forward Landfill contain blanket LCRS <br /> systems. There is no LCRS at the base of the existing Austin Road Landfill. The <br /> following paragraphs describe the LCRS that was constructed in many of the <br /> WMUs at the existing Forward Landfill and will be constructed for future WMUs at <br /> the Forward Landfill. <br /> The LCRS design utilizes two configurations to account for the two types of liner <br /> gradients that will be constructed; base grades and side slopes. On the base of the <br /> WMUs, the LCRS will consist of a one-foot thick layer of granular material sloped <br /> at two percent towards a perforated HDPE leachate collection header pipe. The <br /> header pipe is placed in a "V" trench filled with compacted gravel material. The <br /> • LCRS collection header pipe slopes at a minimum of one percent at 200-foot <br /> centers to ensure adequate leachate removal from the base. The piping and <br /> drainage layer will be directly underlain by the composite liner system. A <br /> geotextile will be used as a rub sheet under all pipes to protect the HDPE <br /> geomembrane liner from potential abrasion caused by the pipes. The drainage <br /> layer will be separated from the operations layer above by a non-woven geotextile <br /> to prevent migration of fine-grained material into the LCRS. <br /> The LCRS design for slopes greater than 15 percent will consist of a geocomposite <br /> drainage net (GDN). GDN will be used due to construction and stability concerns <br /> associated with placement of granular materials on the slope. The transmissivity of <br /> the GDN will be specified to accommodate a minimum of twice the maximum <br /> anticipated leachate flow. No collection pipes are required on the side slopes. <br /> Leachate collected in the LCRS will flow through the drainage layer to the pipes <br /> and subsequently into leachate collection sumps. Submersible pumps located in <br /> each sump will pump leachate into a force main located outside the lined landfill <br /> area. The force main will discharge to lined surface impoundments in which the <br /> • leachate will evaporate. <br /> Forward Landfill JTD 7-1 <br /> L:\Allied\2000.193\Reports\td:Sec-7.0:05/24/02 <br /> BRYAN A.STIRRAT S ASSOCIATES <br />