Phase IV Liner and Phase V Cap

Clearing and grubbing vegetative material, debris, and deleterious materials from the area affected by closure cap construction. All cleared and grubbed materials are to be properly disposed of. Materials removed during clearing and grubbing shall not be mixed with clean soils to be used as fill and subgrade materials. Exposing and cleaning the edge of existing closure lining systems adjacent to Stage C Closure for proper tie-ins to be completed. Remove and salvage existing plywood protective layer along adjacent edges of existing closure lining systems. Uncover the existing northwest storm drainage pipe and remove the pipe from the lower bench area of the closure cap so that closure cap construction can be completed. Uncover and expose the existing gas header pipe on the lower bench of the Stage C Closure area. Uncover and disconnect the existing horizontal and vertical gas collector pipes within the Stage C Closure area from the existing header pipe and gas collection system. Cap, valve, or use some other method to close the ends of the existing horizontal collectors and the connection locations along the header pipe (such that the header pipe maintains vacuum without leakage). Keep the ends of the horizontal collectors exposed throughout construction. Save all wellheads, fittings, valves, etc. for later reinstallation and reconnection of the horizontal collectors and vertical risers to the header pipe and gas collection system. Remove the existing gas header pipe from the north lower bench (to the slope below the lower bench) so the header pipe is clear of the area needed to complete the Stage C Closure. The header pipe shall remain operational for gas collection from other areas of the landfill facility. Remove soil around the vertical riser to the 6” header pipe on the lower south bench and grade the area around the vertical riser to receive geosynthetics for tie-in to the existing liner system and for installation of the geomembrane pipe boot. Moisture conditioning and compaction of all areas to receive fill. Cuts, fill borrow and placement, and final grading of the soil layer above the waste to prepare the subgrade for geosynthetics placement. Providing grade controls and checks required to achieve final grade to within specified grading tolerances. Unload and stage all geosynthetic materials in the designated area and in accordance with manufacture and specified requirements. Geosynthetics anchor trench excavation and backfill. Furnish and installation of the 60-mil HDPE textured geomembrane including the extrusion weld tie-in seam with the existing closure liner systems. Provide all measurements and information to the manufacturer of the boots around the horizontal collectors and vertical risers for proper fabrication of the boots. Furnish and install all fabricated boots around horizontal and vertical gas collectors and around the header pipe risers associated with the vertical gas collectors during placement of the geosynthetic materials. Install a geomembrane boot around the 6” header riser to the 6” header on the south bench. Coordinate and schedule all geosynthetics installation activities (GCL, HDPE geomembrane, and drainage geocomposite) with the Geosynthetics Installer (Sub-Contractor). Extend all horizontal collectors as needed for connection with the gas header pipes. Raise all vertical gas collectors to a height of 3 feet above the final closure surface grade. Raise all vertical header risers associated with the vertical gas collectors to a height of 3 feet above the final closure surface grade. Furnish and install 4” HDPE DR-17 perforated sub-drainage pipe along the interior toe of the lower drainage bench and at the southwest downspout on the upper bench. Furnish and install geocomposite. Install salvaged (and new as needed) 3/4 –inch exterior grade plywood at the anchor trenches along all edges of the new geosynthetics material associated with Stage C Closure. Protective soil cover placement and grading to within the specified grading tolerances of the final closure cap grade. Protective soil cover materials shall be clean of debris that may potentially damage geosynthetic materials during placement. Install the gas collection header pipe back on the lower closure area branch, reinstall all horizontal well heads and manholes with end plugs, and reconnect all horizontal and vertical collectors to the header pipe and gas collection system to allow for gas collection to resume from the Stage C Closure area. Reinstall the northwest downspout onto the lower drainage bench. Furnish and install the southwest storm drainage downspout pipe. Furnish and install the HDPE manhole inlets with frames and grates at the northwest, southwest, and southeast downspout pipes (including connecting the downspouts and the 4” perforated sub-drainage pipe to the inlets). Furnish and install geocell with gravel fill along the drainage ditch at the inside toe of the lower drainage bench and at the southwest downspout on the upper drainage bench. Furnish and install 6” road base. Seeding of the closure area

Division 02 -	Existing Conditions, Landfill Construction and Storage.
Division 31 -	Earthwork, Site Clearing, Earth Moving, Grading.
Division 32 -	Exterior Improvements, Bases, Ballasts, and Paving, Fences and Gates.