The containment efforts at the Site are highly regulated.
Maintenance activities at the Site are regulated and overseen by the Environmental Protection Agency (EPA). The Colorado Department of Public Health and Environment (CDPHE) and the Tri-County Health Department (TCHD) also monitor the Site closely in partnership with the EPA.
The key components of Lowry Landfill’s containment and treatment plan are:
Underground Barrier Walls:
A system of subterranean walls constructed to bedrock protects fresh groundwater from entering the Site and prevents contaminated groundwater from leaving the Site.
North Boundary Barrier Wall and Sump:
A subterranean clay wall with a gravel blanket in front of it collects all of the contaminated groundwater that naturally flows to it. The extracted groundwater is then treated at the onsite water treatment plant. The North Boundary Barrier Wall area has an extensive monitoring network around it to assure continued containment. Groundwater is extracted 24/7/365.
Onsite Water Treatment Plant:
A treatment plant onsite removes all Site chemicals to safe standards and leaves a minimal environmental footprint by using a natural biological process. It treats approximately 1.5 million gallons of contaminated groundwater every year.
North Toe Extraction Systems:
Trenches and wells around the perimeter of the landfill, and at two location north of the landfill, collect contaminated groundwater. The extracted water is pumped to the Site’s water treatment plant.
Gas-to-Energy System:
Landfill gases—mostly methane and carbon dioxide—are the natural byproduct of decomposing waste that was buried underground at the landfill. The Site’s gas-to-energy system extracts the gases, burns them, and converts them into electricity for a local utility company.
Landfill Cover:
The former landfill area is covered by 4 to 12 feet of compacted clay and soil. The “cap” reduces infiltration of rain and snow into the soil, which minimizes further groundwater contamination.
Groundwater Monitoring Wells and Compliance Program:
More than 500 monitoring wells within and outside the Site are routinely monitored to ensure the community is protected.
Surface Water Removal Action:
An unnamed creek flows through the Site. Contaminated groundwater is kept separate from clean surface water within the creek stream bed by a channel of impermeable material installed beneath the stream bed and covered by a clay barrier. This provides a pathway for groundwater to flow north without contacting surface water. Clean surface water flows above the permeable channel without coming into contact with contaminated groundwater flowing underneath the clay barrier.
Waste Pits:
Three waste pits located north of the landfill, but south of the NBBW were remediated. Solvents were extracted from the northern pit and an impermeable cover placed over it, the middle pit was excavated, treated and disposed of, and the southern pit was thermally treated and an impermeable cover placed over it.
Institutional Controls:
Permanent land and groundwater restrictions that run with the land were placed on and offsite. These controls prevent groundwater uses, and land uses that are incompatible with the EPA selected remedy.
Extra Measures:
Although not part of the EPA’s formal cleanup plan, property was purchased around the former landfill as a precautionary measure. These properties are deed restricted to permanently prohibit groundwater use and to control future development around the Site, so land uses are compatible with cleanup and containment objectives and are in the public interest. The properties are one-quarter mile on the east. The properties one-half mile west of the site and to the south were sold to E-470 and a local park district and Xcel respectively. No such zone was purchased to the north because the active Denver Arapahoe Disposal Site facility adjoins the Lowry Landfill Site at the north end. To see what is happening with buffer areas in the public interest go here.