Lowry Landfill

Overview

Lowry Landfill sits in unincorporated Arapahoe County, Colorado. From the mid-1960s until 1980, it accepted about 138 million gallons of industrial waste alongside municipal refuse and sewage sludge in 78 unlined trenches. The site was added to the federal Superfund list in September 1984 and has been under active cleanup ever since. Remedial construction wrapped up in September 2006, and the site is now in the long-term maintenance phase.

More than 250 chemical contaminants have been identified across groundwater, surface water, soil, sediment, and solid and liquid waste. These include volatile organic compounds (VOCs) such as trichloroethene, tetrachloroethene, benzene, vinyl chloride, and chloroform. Heavy metals and metalloids found include arsenic, lead, cadmium, chromium, and mercury. The site also contains pesticides like DDT, dieldrin, and chlordane, polychlorinated biphenyls (PCBs), semivolatile organic compounds, radioactive materials, and 1,4-dioxane. EPA determined all of these pose an unacceptable risk to human health or the environment.

Cleanup is organized into six operable units covering shallow groundwater and waste, landfill solids, landfill gas, soils, and deep groundwater. The remedy uses containment, collection, and treatment. Key components include a landfill cover, a perimeter slurry wall, groundwater extraction and treatment systems, a subsurface barrier wall, landfill gas extraction, waste pit excavation, and a network of over 460 monitoring wells. A landfill gas-to-energy plant opened in September 2008 and converts 630 million cubic feet of methane annually into 3.2 megawatts of electrical power for roughly 3,000 households. The Work Settling Defendants carry out ongoing groundwater monitoring and maintenance under EPA and Colorado state oversight.

EPA's January 2022 five-year review confirmed the remedy currently protects public health and the environment. Human exposure and groundwater migration are both under control. A 1,4-dioxane plume north of the site, identified in 2003, showed trace concentrations that EPA determined do not pose risk to the public or environment. Two nearby private wells are sampled annually and have never detected site-related contaminants. The site has not yet been deleted from the National Priorities List, and the next five-year review is estimated between January and March 2027.

Institutional controls limit on-site land use to landfilling, monitoring, remediation, and compatible activities. Restrictive covenants, zoning restrictions, and an executive order from Denver's mayor are all in place and enforceable by EPA and the Colorado Department of Public Health and Environment (CDPHE). Community members with questions can contact EPA or CDPHE, or request administrative records by calling 303-312-7273 or 800-227-8917 extension 312-7273.