Laserfiche WebLink
Draft Supplemental Environmental Impact Report Page lIl-30 ' <br /> Forward Inc.Landfill 2018 Expansion Project <br /> RRF area. A third sedimentation/detention basin,located on the northwest side of the existing <br /> landfill,directly west of WMU FU-03,collects runoff from the northern portion of the landfill. <br /> For purposes of the 2018 Expansion Project,the sedimentation basins currently located in the <br /> southern portion of the site would be relocated. Closure and relocation of the sedimentation <br /> basin would be conducted in accordance with applicable regulations and as approved by the <br /> regulatory agencies.An additional sedimentation pond and leachate collection pond may be <br /> added in the area of the existing administrative offices,if necessary. <br /> The erosion control measures incorporated in the site design include the following: <br /> • Collection and control of runoff,diverting it away from highly erodible areas <br /> • Construction of intermediate and final landfill slopes with drainage benches at <br /> intervals designed to control slope runoff velocities and volumes <br /> • Hydroseeding with fast germinating drought-tolerant grass seed on intermediate <br /> surfaces that would be exposed for more than 180 days and all surfaces once they reach <br /> final grade. Seeded surfaces would be watered until growth is well established. <br /> Soil erosion from the proposed landfill slopes was calculated to be less than the maximum allowed <br /> by the EPA for landfill final covers. The vegetative layer of the final soil cover would be seeded <br /> with native grasses to protect the upper layer of soil,and to minimize erosion. <br /> Surface Water and Erosion Maintenance and Monitoring <br /> Water collected in the three sedimentation basins(on the northwest side of the existing landfill, <br /> and in the southwest corner of the site,on either side of the South Fork)is sampled qua#efl)­when <br /> there is discharge,in accordance with the site's Storm Water Pollution Prevention Plan <br /> (SWPPP) s,and Mitigation Monitoring and Reporting Program(MMRP). <br /> Leachate Control and Recovery Systems <br /> As discussed in Existing Permitted Waste Management Units and Facilities,above,the majority of <br /> the existing WMUs at the existing Forward Landfill contain blanket Leachate Collection and <br /> Recovery Systems(LCRSs). There is no LCRS underlying the northern portion of the landfill(the <br /> former Austin Road Sanitary Landfill),and portions of the eastern part of the site(original <br /> Forward Landfill). However,there is a LCRS located above the top of the former Austin Road <br /> Landfill to drain leachate from WMUs FU-03 to FU-08 that overlie the former Austin Road Landfill <br /> top deck. <br /> The LCRS design utilizes two configurations to account for the two types of slopes encountered; <br /> base grades and side slopes. On the base of the WMUs the LCRS consists of a 1-foot thick layer of <br /> granular material sloped towards a system of perforated HDPE leachate collection header pipes. <br /> The LCRS collection header pipes slope at a minimum of one percent toward the sumps. The <br /> piping and drainage layer is directly underlain by the composite lining system. A geotextile is <br /> used under all pipes to protect the HDPE geomembrane liner from potential abrasion caused by <br /> the pipes. The drainage layer is separated from the operations layer above by a nonwoven <br /> geotextile to prevent migration of fine-grained material into the LCRS. <br /> r <br /> r <br />