Central County Solid Waste Disposal Complex – Phase I
This project is a 60-acre Class I Landfill Closure consisting of earthwork, Geosynthetic liner, gas extraction wells and piping, storm water piping and conveyance systems, and material stockpiling.
Earthwork – The earthwork is broken into two major items. The intermediate layer is graded prior to liner installation. This involves roughly regrading material in place as well as roughly 130K CY of material import from an onsite borrow. The material is graded to plan grades, adhering to minimum and maximum slope requirements. Once the liner system is in place, two feet of cover material (also from onsite borrow) is placed on the top, north and east slopes (180K CY). The west slope is covered with an imported sand layer (14K CY).
Geosynthetics- The portions of the landfill that are to be closed are the top, north, and east sides. These areas receive a 40 mil LLDPE liner with a geocomposite (2 million SF). The west side will be covered by the waste being placed in phase II. Because of this it is treated similarly to the bottom liner and will receive a 60 mil HDPE liner with a geocomposite (175K SF). Finally, the south side is covered temporarily using an exposed TPO liner from Firestone (570K SF). This face requires no cover material.
Gas Extraction- The gas collection work consists of drilling and installing 44 gas wells and associated force main, air, header and lateral piping. Along with the piping was the installation of three valve boxes and a sump. All existing gas wells were also raised to meat final grades.
Storm water- The storm water systems includes the installation of corrugated plastic pipe, RCP, one inlet, filter point fabric line pipe outlets and riprap ditches.
Material Stockpile- This work involves moving 250K CY of material from the borrow are to a stockpile next to the active landfill to be used in the future by the county as cover material. The borrow area is about 1 mile from the active face.