Project Overview
This project consisted of 55 acres of permanent landfill closures and 21 acres of temporary closures to enhance the gas collection, while greatly reducing odors given off by each landfill. Seneca Meadows has a gas-to-energy facility located on -site, which operates on the methane gas collected from the landfill. This methane gas runs the engines within the facility, which produces electricity that is sent to the public grid for use within the local community.
CHALLENGE
76 acres of the project were completed on extremely steep side slopes ranging from 30 – 40% in grade and were approximately 500 to 700 feet in length. The areas were graded and the surface prepared for the installation of the liner. There were over 900 penetrations through the liner, requiring special liner boots on each protrusion to ensure an air tight seal. The temporary closure consisted of site grading and placement of the polyethylene liner, while permanent closures consisted of placing two feet of clay carefully over the geosynthetics, to prevent any damage to them. Drainage was installed in the clay layer and permanent swales were constructed on the surface, to control the water runoff. The project also involved extensive sediment, erosion and dust control measures to maintain the site. Additionally, 6,000 linear feet of gas vent piping and 58 gas vents were installed to allow for increased gas extraction from the site. All the site work was highly weather sensitive, particularly with excess moisture that created unsafe slope conditions.
SOLUTION
To keep any water from entering the landfill, approximately 215,000 cubic yards of clay and 45,000 cubic yards of topsoil were placed over a sensitive geosynthetics. While protecting the liner system during the excavation and installation of the underdrains, more than 17,000 feet of underdrain piping was installed in the soil layer. With hundreds of loads of trash being hauled into the landfill daily, it was a real challenge to complete our work and maintain uninterrupted flow thru the landfill. With the use of flaggers and an experienced staff, the owner was able to operate without any interruptions. Proper safety training, coordination and precise scheduling ensured protection of the workers and maintained uninterrupted traffic flow for the hundreds of waste trucks, landfill traffic and construction related vehicles.
RESULT
As with all landfills, odors are always a big concern. By installing more than 75 acres of liner and cover soils, the odors were greatly suppressed. This product and the installation of additional gas vent piping, enhanced the collection of the methane gas produced by the landfill. The methane gas collected is then used to fuel the on-site power plant, which in turn provides the local community electricity. The methane gas is now better contained and collected for power production.
