Comprised of compacted clay and soil, a landfill cover, or “cap,” minimizes the amount of rainwater that can seep into the ground beneath the site, thus reducing the amount of groundwater that could become contaminated by contact with buried wastes in the landfill.
North Face Landfill Cover
When it was completed in 1994, Lowry Landfill’s cleanup plan required that an additional 2 feet of compacted clay cover be placed over a 2-foot soil cover that was placed on the north face of the landfill mass in 1990. Completed in 1999, the new cover involved placing approximately 100,000 cubic yards of soil and clay over 29 acres. The placement increased the total thickness of the North Face Landfill Cover to 4 feet, equal in thickness to the covers on other surface areas of the landfill mass. The cover is designed to reduce the potential for infiltration of rain and surface water into the landfill mass, prevent erosion, further reduce the potential for landfill gas release and better contain landfill waste.
New Landfill Cover
Although closed depressions in the landfill cover were filled and re-graded in 2002, the top surface of the landfill remained relatively flat. This prompted an evaluation of long-term maintenance alternatives that would continuously promote positive drainage of precipitation off the cover. In 2005, the Colorado Department of Public Health and Environment approved an Engineering Design and Operations Plan that would entail construction of a cover with a 5 percent slope that, over time, might reduce to a 2 to 4 percent slope as the landfill mass settled. The plan allowed for placing construction and demolition debris and other inert waste over the top of the current landfill, followed by construction of another top cover.
- Reduces contamination of new groundwater
- Prevents erosion
- Reduces landfill gas release
- More effectively contains landfill waste
- Prevents exposure to humans and the environment of contaminated groundwater
- Protects human health by preventing inhalation of landfill gas
- Protects human health by preventing direct contact with landfill waste
- Protects clean surface water
- Prevents migration of landfill waste