ARCHIVED REPORTS_2008_19 - Laserfiche WebLink

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• WMU FU-08 will be designed to withstand the Maximum Credible Earthquake (NICE)without damaging the lining, leachate, or surface drainage control systems. • Leak location testing will be performed on the geomembrane on the base of the cell following placement of the operations layer The southern portion of WMU FU-08 will be constructed in the former Austin Road Landfill Borrow Pit and Expansion Area,directly south of the Former Austin Road Landfill and east of WMU FU-06 (see Design and Construction Documents, Waste Management Unit FU-08,Forward Landfall,Lewis Engineering, 2008). The base liner will encompass approximately 7.5-acres and will extend approximately 900 feet in the north-south dimension and 400 feet in the east-west dimension. The base of WMU FU-08 at the top of clay liner will range from approximately elevation 15-feet to 22- feet,which is about 18 to 25 feet below the surrounding ground surface.A composite lining system consisting of a 2-foot-thick clay liner overlain by a 60-mil, high-density polyethylene (HDPE) geomembrane, and LCRS consisting of 1 foot of granular drainage material will be constructed on the WMU FU-08 base. HDPE leachate tanks will be placed at the eastern edge of the WMU FU-08 base, from which leachate will be pumped and removed. Side slope liners will be constructed on the northern slope. The side slope liner on the north slope consists of a geosynthetic clay liner (GCL) overlain by a 60-mil, single-sided textured, HDPE geomembrane, and a single-sided geocomposite drainage net (GDN). A portion of the northern WMU FU-08 slope is at an approximately 5:1 (horizontal to vertical)slope and is underlain by the former Austin Road Landfill. To provide support for the side slope liner,an approximately 4 to 5-ft thickness of subgrade fill(1-ft of subgrade fill was previously placed as intermediate cover over the former Austin Road Landfill) will be placed and compacted over the portion of the former Austin Road Landfill that underlies WMU FU-08. The northern portion of WMU FU-08 encompasses a portion of the interim final cover that was constructed over the former Austin Road Landfill in the fall of 2002. The 2-ft foundation, 1-ft thick clay liner, and 1-ft vegetative layer of the interim final cover serve as the base components of the WMU FU-08 cell in this area. The interim final cover generally grades at a 3 percent slope from north to south. Construction of the remainder of the northern portion of WMU FU-08 consists of placement of a 6- inch thick blanket LCRS composed of granular drainage material with perforated piping spaced at approximately 200-ft centers. The blanket LCRS is both underlain and overlain by an 8-ounce nonwoven geotextile. A 1-ft protective operations layer overlies the blanket LCRS. Leachate in the northern portion of WMU FU-08 is routed through 3-inch perforated pipes and collected along the southern top deck boundary of the former Austin Road Landfill. The cell is bounded by lined perimeter berms on the north,south,and east sides to maintain leachate within the cell. The western side of the northern portion of WMU FU-08 will be connected to WMU FU-06. Leachate exits the cell in 3-inch diameter leachate header pipes that route leachate to leachate tanks. Class III Refuse placed in the northern portion of WMU FU-08 will be separated from the Class H Page 2