ARCHIVED REPORTS_2008_26 - Laserfiche WebLink

Home Browse Search

2.3.2 SURFACE WATER MONITORING Surface water monitoring is completed quarterly at both the existing Austin Road and Forward Landfills in accordance with each site's WDR's. Monitoring is performed for the North Branch and South Branch of Little Johns Creek for the existing Austin Road and Forward Landfills, respectively (see Figure 2). Table 7 lists the surface water monitoring stations at the site together with their current and expected future use. 2.4 LEACHATE COLLECTION AND REMOVAL SYSTEM/MONITORING The majority of the existing WMUs at the Forward Landfill contain blanket leachate collection and removal system (LCRS) systems. There is no LCRS on the base of the existing Austin Road Landfill. The following paragraphs describe the LCRS that was constructed in many of the WMUs at the existing Forward Landfill and will be constructed for future WMUs in the future Forward Landfill. The LCRS design utilizes two configurations to account for the two types of slope configurations encountered; base grades and side slopes. On the base of the WMUs, the LCRS will consist of a 1-foot thick layer of granular material sloped at 2 percent towards a perforated high density polyethylene (HDPE) leachate collection header pipe. The header pipe is placed in a "V" trench filled with compacted gravel material. The LCRS collection header pipe slopes at a minimum of 1 percent at 200-foot centers to ensure adequate leachate removal from the base. The piping and drainage layer will be directly underlain by the composite lining system. A geotextile will be used as a rub sheet under all pipes to protect the HDPE geomembrane liner from potential abrasion caused by the pipes. The drainage layer will be 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 will consist of a geocomposite drainage net (GDN). GDN will be used due to construction and stability concerns associated with placement of granular materials on the slope. The transmissivity of the GDN will be specified to accommodate a minimum of twice the maximum anticipated leachate flow. No collection pipes are required on the side slopes. Leachate collected in the LCRS will flow through the drainage layer to the pipes and subsequently into leachate collection sumps. Submersible pumps located in Forward Landfill PCPCMP 2-5 L:\Allied\2000.193\Reports\FinaIPCPCMP:FL-sec2.doc:5/21/02 BRYAN A.STIRRAT s ASSOCIATES