National Priorities List (NPL) History
Site Type: Final NPL
Street Address: 1600 S. 66th Street
ZIP Code: 80303
EPA ID: COD980499255
Site Aliases: Landfill Inc.
Congressional District: 2
Updated February 2013
In February 2013, solar developer Clean Energy Collective began construction of a 500-kilowatt solar project on property adjacent to the Marshall Landfill. The EPA helped facilitate the location of the solar garden while ensuring that onsite groundwater monitoring remains active. The project is the first to be completed under Xcel Energy’s community solar program, as required by State of Colorado legislation enacted in 2010. For more information, see the story and photo on our Facebook page.
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, The 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.
The 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.
|Media Affected||Contaminants||Source of Contamination|
|surface water, groundwater, soil, liquid waste||benzene, trichloroethylene (TCE), tetrachloroethylene, barium, iron, manganese, zinc||landfill operations|
These cleanup activities were completed in 1993 by the potentially responsible parties:
- Constructed a groundwater collection and treatment system.
- Regraded and revegetated the landfill soil cover.
- Drained and treated leachate from lagoons.
- Installed a pipeline to convey water from the Community Ditch through the landfill to prevent further contamination of the groundwater.
Cleanup construction was completed in August 1993.
Community involvement plays an important role in the Superfund process. The EPA uses a number of different tools and resources to promote effective, on-going, meaningful community involvement. The goals of the Superfund community involvement program are to:
- Keep communities affected by sites informed throughout the cleanup process.
- Provide opportunities for communities to comment and offer their input about site cleanup plans.
- Facilitate the resolution of community issues tied to a site.
Community comment was solicited for the five-year review completed in August 2011. The five-year review report is posted in the Site Documents section below.
The EPA places a high priority on land reuse as part of its Superfund response program mission. The agency tries to select cleanup options that encourage and support future use of a site. The EPA uses two fundamental methods to facilitate reuse of Superfund sites:
- Exploring future uses before the cleanup remedy is implemented, an approach that gives the Agency the best chance of designing cleanup remedies to support the likely future use of a site.
- Working with landowners and communities to remove barriers not considered necessary for the protection of human health or the environment at those sites where remedies are already in place.
One option for reuse is the siting of clean and renewable energy projects on contaminated (or formerly contaminated) lands. As part of this effort, the EPA is evaluating the potential for energy projects on these properties and working with landowners and communities to identify ways to remove barriers to such projects.
Sites made ready for use are deemed "Site-wide Ready for Anticipated Use," which means that all cleanup goals have been achieved for both current and reasonably anticipated future land use.
While the EPA has determined that this site meets the criteria for Site-wide Ready for Anticipated Use, no future uses of this site are currently planned. The site is located in a rural land use designation area that the prohibits the development of the Superfund site.
Land Use Controls and Other Institutional Controls
Land use controls are the most common type of institutional control (IC). ICs are administrative or legal controls that help reduce the likelihood for human exposure to contamination. ICs can also help protect the integrity of the remedy. Examples of ICs are:
- Zoning ordinances.
- Environmental covenants.
- Deed notices.
- Well-drilling restrictions.
- Building permits.
- Informational advisories.
The 2003 ESD identified that institutional controls (ICs) were necessary to ensure long-term protection of the engineered remedy and to prevent future release of contamination. The site has implemented ICs containing two components, informational and enforcement. Map showing where land use controls apply (PDF, 1 pg, 2.6MB, about PDF )
- Informational—an electronic map in the Boulder County Planning Department outlines the landfill boundary and identifies the property as a Superfund site. All applications related to development or changes in land use are submitted to the county.
- Enforcement—a rural Preservation Planning Area land use designation prohibits the development of the Superfund site. The land use restriction is enforceable by Boulder county and all surrounding municipalities through the Intergovernmental Agreement US 36 Corridor Comprehensive Development Plan (PDF, 12 pp, 715K, about PDF ) effective June 20, 2000. Specifically, the agreement states that the municipalities "shall not grant a permit for development" for all areas within the Rural Preservation Planning Area including the Superfund site.
The EPA or the lead agency conducts five-year reviews following the start of a Superfund cleanup when contamination is left on the site. These reviews are repeated every five years. We use these reviews to determine:
- How the remedy is working.
- If the remedy remains protective of human health and the environment.
The EPA completed the fourth five-year review of the Marshall Landfill Superfund Site on August 4, 2011. You may view the report in the Site Documents section below or at one of the document repositories. The fifth five-year review will be completed by August 2016.
You will need Adobe Acrobat Reader to view some of the files on this page. See the EPA's PDF page to learn more.
Fourth Five-Year Review Report, August 4, 2011 (PDF, 45 pp, 1.5MB)
Explanation of Significant Differences, September 8, 2003 (PDF, 14 pp, 63K)
Explanation of Significant Differences, November 1, 1992 (PDF, 9 pp, 23K)
Record of Decision, September 26, 1986 (PDF, 25 pp, 54K)
Remedial Project Manager
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (EPR-SR)
Denver, Colorado 80202-1129
800-227-8917 ext. 312-7122 (toll free Region 8 only)
Community Involvement Coordinator
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (8OC)
Denver, Colorado 80202-1129
800-227-8917 ext. 312-6633 (toll free Region 8 only)
State Project Officer
Colorado Department of Public Health and Environment
4300 Cherry Creek Drive South
Denver, CO 80246-1530
888-569-1831 ext. 3411 (toll free)
View Documents at:
Boulder Public Library (Main)
1001 Arapahoe Avenue
Boulder, CO 80302
EPA Superfund Records Center
1595 Wynkoop Street
Denver, CO 80202-1129
800-227-8917 ext. 312-6473 (toll free Region 8 only)