Branch Highways of Roanoke, VA, has begun work on a $1.42-million project expanding the Smith Gap Regional Landfill (Phase III/ IV, liner system and sediment basin No. 3) located in Roanoke County in southwestern Virginia. Branch Highways is adding seven additional cells that will cover a total of 2.8 hectares (7 acres). The first cell will be ready for use by May 31; remaining cells will be operational by June 30. An additional 1.6 hectares (4 acres) is being prepared as a sediment basin that will catch storm water run-off for future cells and includes a 10.7-meter (35 ft.) berm, a dam-like structure that prevents leachate, a toxic by-product of the landfill, from escaping into the soil.
Branch Highways began earthmoving in mid-December, but had to suspend work from mid-January to mid-February because conditions were simply too wet. Nevertheless, Andrew Bach, project engineer, is confident they will complete the job on schedule. Coordination with the railroad has also been somewhat challenging. The No. 8 fill being used on the project is delivered via rail, which is also how the refuse for the landfill arrives. Typically, Branch Highways receives 400 to 500 tons of No. 8 per delivery.
Equipment used on the project includes: a Caterpillar D5H XL II bulldozer, a John Deere 750C bulldozer, a Caterpillar 963GP loader, a Mich/Volvo L90B loader, a John Deere 892 excavator, three Volvo A25C articulated trucks, and a Dynapac Ca251 PD compact sheep’s foot roller. All of the equipment is part of Branch Highways’ fleet, mostly purchased from Roanoke area dealers such as Carter Caterpillars, Mitchell Distributing, J.W. Burress, and Shelton-Witt Equipment. Bach explained that Branch Highways typically retires all rental equipment from projects between December and March, due to weather considerations. He said the company will rent a Frialen fusion machine for the perforated leachate pipe. The machine trims pipe ends, preheats them and then welds them together once they’re hot. The fusion welded pipe is cheap, strong, and easy to work with; Bach said 30.5-meter (100 ft.) sections can be maneuvered without breaking.
The liner system for Smith Gap will consist of seven layers, and Branch Highways is now working on the bottom level, the basegrade, and the construction of two riprap ditches, which will catch storm water. Because the landfill is located on a hill, gravity works to drain off storm water. Approximately 3,600 metric tons (4, 000 tons) of riprap will be required for the ditches, which will span 609.6 lineal meters (2, 000 lineal ft.). Above the basegrade will be select structural fill, then a geosynthetic liner, then a geomembrane. The next layer will be the perforated leachate pipe, designed to collect leachate, and above that will be a 22.9-centimeter (9 in.) drainage blanket composed of No. 8 fill. No. 57 aggregate fill will be used around the leachate pipes. The project will require 10,800 metric tons (12,000 tons) of No. 8 and 4,500 metric tons (5,000 tons) of No. 57. The top layer will be an operational cover of dirt with a plastic rain barrier over it.
Bach said the basegrade was accomplished with the John Deere 750C bulldozer, the Caterpillar D5H XL II bulldozer and a Caterpillar D8 bulldozer using a semi-automated grade control to ensure the grade was plus or minus one inch. Additional construction will include a sump, a 9.1-meter (30 ft.) type A berm, and a leachate manhole to be located at the base of the hill where the leachate pipes will meet. Ten people are employed on the project, and Bach said they will use subcontractors from a Wisconsin-based company, Geo Synthetic Inc. (GSI) to install the geomembrane liner for the landfill.
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