marshall landfill

1600 S 66TH STREET

The 160-acre Marshall Landfill site is located at the foothills of the Rocky Mountains, about three miles southeast of Boulder. The Marshall Reservoir is immediately west of the site. In 1981, water that collected contaminants as it leached down through the landfill was discovered seeping into the open Community Ditch. The ditch carries drinking water from the reservoir to the city of Louisville and irrigation water to downstream ranchers. The inactive landfill had high levels of contaminants in both surface water and groundwater. Identified contaminants were benzene, trichloroethylene (TCE), tetrachloroethylene, barium, iron, manganese and zinc. Benzene and TCE are known to cause cancer; the others are toxic to fish and other aquatic life. Because significant levels of contamination from the landfill were found in surface and groundwater on and next to the landfill, EPA added the site to its Superfund National Priorities List in 1983. Current operation and maintenance activities include operating a groundwater treatment system, maintaining the landfill cover and groundwater monitoring. A five-year review was completed in September 2006. The review found that the remedy, as designed, constructed and operated is protective of human health and the environment. EPA issued an Explanation of Significant Differences (ESD) in September 2003 that documents amendments made to the 1986 Record of Decision for Marshall Landfill. The ESD describes new or changed standards for groundwater and surface water at the site. At the time of the Record of Decision, groundwater standards did not exist for several volatile organic compounds. In addition, many of the state of Colorado's surface water quality standards have been updated. The ESD determines that standards be brought up to date in order to be protective of human health and the environment and to assure that the original remedy is protective.

Hazardous Ranking Score

0 / 100

A score of 28.5 or higher qualifies a site for the Superfund National Priority List.

Regional Contact

Region 8
Phone: (303) 312-6312

Contact Region



Site Inspection
Preliminary Assessment
Final Listing On NPL

Contaminants & Health Effects

      Endocrine Disrupter
      Reproductive Toxin
      Persistent, bioaccumulative and toxic


        African American
        American Indian and Alaska Native
        Native Hawaiian


        People living
        within a 1 mile radius


        Average Income


        Occupied homes

        Potentially Responsible Parties

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