Laserfiche WebLink
II. Project Description <br /> operation/drainage layer,60 mil high density polyethylene(HDPE)liner,and a 24-inch <br /> compacted clay layer having permeability of 1 x 10-7 cm/sec. The base liner for the vertical <br /> expansion would be constructed approximately 30 years after the existing landfill is capped. The <br /> specific design for the vertical expansion would depend on the settlement of the existing landfill. <br /> The HDPE liner would serve both as an added barrier to protect groundwater and as a flow <br /> surface for leachate. The protective layer would serve as protection for the other liner <br /> components during the initial stages of landfilling activities. Other materials may be used in <br /> later phase developments,if the materials meet applicable regulations and.performs equal to or <br /> better thazi HDPE. <br /> Groundwater varies between-48 feet to-12 feet mean sea level (MSL),with an average of <br /> -35 feet MSL in the expansion area(Kleinfelder, 1988). The maximum depth of the liner,not <br /> including the leachate collection trenches and sumps,is 20 feet MSL. This results in a minimum <br /> separation of 32 feet between the waste and groundwater. <br /> j,,�Arhate Go11_ection <br /> The proposed landfill's leachate collection plan includes a drainage system,a leachate collection <br /> system,and a leak detection system. For purposes of this project,leachate is any liquid that has <br /> come in contact with or percolated through refuse. Any surface water run-off that could have <br /> contacted solid waste or include leachate would be handled by the leachate collection system. <br /> Drainage System <br /> The drainage system consists of a drainage and operation layer. The drainage layer would <br /> provide drainage from the expansion area to the leachate collection trenches,described later in <br /> this section. The operation layer is above and protects the drainage layer. The drainage layer <br /> would consist of either a minimum 12-inch thick layer of sand or gravel with a minimum <br /> permeability of I x 10'1 cm/sec or a geonet drainage layer providing similar performance. A <br /> geotextile filter would separate the drainage and operation layers and prevent soil fines from <br /> entering the drainage layer. The operation layer would be a minimum of 12 inches to protect the <br /> liner,if the drainage layer is sand or gravel. If a geonet drainage layer is used,the operation <br /> layer would be a minimum of 18 inches,to protect the geonet and liner. <br /> II.11 <br />