Once the site was graded to specifications, Adam’s European put down a geocomposite gas venting layer, which allows the methane gas trapped beneath the surface to transmit to the gas vents. Next, the contractor installed a polyethylene geomembrane liner that would waterproof the gas venting layer and allow drainage without erosion. Another layer consisting of drainage geocomposite that acts like a flat pipe to collect water from the top of the polyethylene geomembrane liner and direct it to the new drainage system was also be installed. A 1.5-foot layer of silty soil, was to be placed on top of the drainage geocomposite followed by a 6-inch layer of topsoil to be used on top of the cap. This top layer will be hydroseeded to prevent erosion.
In addition, Adam’s European was contracted to cut some areas of the landfill and use the material as fill elsewhere in the process of reshaping the site to the specified grades. However, it was not a typical excavation project in which dozer operators make long passes and keep their machines moving almost constantly. The process was more painstaking for two reasons.
- Trash compacts more but is less homogeneous than most types of dirt.
- The landfill contains many tons of broken concrete. That material cannot be pushed with a dozer but must be picked out piece by piece with excavators and moved to fill areas with dump trucks.
There was nothing that Adam’s European could do about the relatively slow process of moving material around the site, but its use of the 3D-MC2 system allowed the company to recoup significant efficiency in terms of staking - or the lack thereof.
Mesh Consulting, Limerick, Penn., had built a two-dimensional CAD file from the official survey and a second file indicating the trash in the landfill. For both files, Mesh converted the lines in the digital file into three-dimensional lines and then added contour lines. Mesh then converted the files from CAD to Topcon-3D Office, saving linework as an LN.3 file and the 3-D surface as a TN.3 file. The files were then loaded into the 3D-MC2 systems in Adam’s European’s two dozers. By using two separate files for finished grade and trash, the contractor eliminated the need to drive stakes in the ground.
Don Talend, Write Results Inc., West Dundee, Ill., is a print and e-communications content developer specializing in covering construction, technology and innovation.