Installation: Rocky Mountain Arsenal
County: Adams County
State: CO
Size: 17,228 acres
Point of Contact: U.S. Army Environmental Center Public Affairs Office
Public Affairs Office Phone Number: 410-436-2556
Servicing Installation Management Agency Office: Northwest Region Office
National Priorities List: Yes
EPA Region: 8
Restoration Advisory Board Available: Yes
Funding to Date: $1,266.0 million
Cost to Complete: $719.5 million
Estimated Date for Remedy in Place/Response Complete: FY2010
Military Munitions Response Program Actions Identified: No
Mission: Manufactured and stored chemical munitions
Contaminants: Pesticides, chemical agents, volatile organic compounds, chlorinated organics, polychlorinated biphenyls, unexploded ordnance, heavy metals, solvents
Media Affected: Groundwater and soil

Rocky Mountain Arsenal (RMA) operated as a chemical munitions production facility from 1942 until 1982. It has been the focus of an aggressive soil and groundwater contamination cleanup program since the 1980s. Contaminated sites included liquid waste in unlined and lined lagoons and basins, open burning and detonation areas, and landfills that received both liquid and solid wastes. Primary contaminants of concern are compounds used for chemical weapons material production and pesticides. In 1987, the U.S. Environmental Protection Agency (EPA) placed the installation on the National Priorities List (NPL). The Army and EPA signed an interagency agreement and a federal facility agreement in Fiscal Year 1989 (FY89). The installation was divided into two operable units (OUs), one containing all on-post sites and another for off-post sites. In 1994, the Army converted its technical review committee into a Restoration Advisory Board (RAB). In 1996, the Army, EPA and Shell Oil Company (a potentially responsible party) formed an oversight partnership that developed a remedial design (RD) implementation schedule for the On-Post OU in FY97. The initial 5-year review report covering both OUs was competed in FY01. Environmental studies have identified 209 sites at this installation. During FY96, the Army and regulators signed Records of Decision (RODs) for both OUs at the installation. Prior to the signing of the ROD, the Army completed 14 interim responses at 17 sites at the arsenal. The Army installed five groundwater extraction and treatment systems on-post and one off-post. Contaminated soil responses have included excavations and treatment of soil, disposing of contaminated soil in landfills, and capping contaminated soil sites.

Progress to Date:
In FY99, the Basin A consolidation area, Phase I of the hazardous waste landfill (HWL) construction, and the landfill wastewater treatment system reached construction complete status and became operational. A remedial action (RA) was completed for the off-post well closure. The Army completed the RD for seven RAs and began four RDs for Phase II RAs.

In FY00, the Army completed the RA for the post-ROD removal actions for structures. The Army also completed RAs for four Phase I projects and the confined flow system well closure project. RDs were also completed for the four remaining Phase I projects and one of the Phase II projects. The Army completed treatability studies for two Phase II projects.

In FY01, the Army completed RAs for two Phase I projects. RDs for three Phase II projects and one Phase III project also were completed. As part of RA activities for one of the Phase I projects, ten M139 bomblets containing the chemical agent Sarin (GB) were discovered. The Army destroyed the bomblets using the Explosive Destruction System. The Army completed the first Comprehensive Environmental Response, Compensation, and Liability Act 5-year review report, which covered both OUs.

In FY02, the installation completed the RD of the last disposal facility landfill and one Phase III project. The Army awarded RA contracts for one Phase II and one Phase III project. The RAs for one Phase II project and one Phase I project were completed. The Army continued implementation of all installation-wide programs and the operation and maintenance of groundwater treatment systems. The EPA published the notice of intent to delist approximately 940 acres from the NPL in the Federal Register. The RAB continued to focus on providing input and comments to remediation designs, as well as sharing information with other interested stakeholders.

FY03 IRP Progress:
The Army completed the RD for the Section 36 Balance of Areas and the Basin F Wastepile projects. The installation completed the RA for one Phase I project (Burial Trenches) and three Phase III projects (Secondary Basins Soil Remediation, Section 35 Soil Remediation, and North Plants Structures Demolition). The Army awarded RA contracts for two Phase I projects, one Phase II project, three Phase III projects and one Phase IV project. One Phase III RA contract was not awarded due to additional design work required. The Army continued to implement installation-wide programs and operate groundwater treatment systems. Of the 940 acres scheduled for deletion from the NPL, 929 have been transferred to the General Services Administration for disposal. The innovative treatment technology for a Phase II project (Hex Pit remediation) failed, causing a delay in the remedy.

FY03 MMRP Progress:
RMA completed an inventory of closed, transferred, and transferring ranges and placed the inventory in the on-site library. The inventory identified 25 closed unexploded ordnance, discarded military munitions, or munitions constituents sites and 3 closed military ranges totaling 459 acres. None of the sites were found to be eligible for inclusion in the MMRP.

Plan of Action:
Plan of action items are grouped below according to program category.


  • Begin construction of the South Plants cover and the Enhanced HWL in FY04.
  • Continue operation of the Resource Conservation and Recovery Act HWL and the Basin A Consolidation area in FY04.
  • Complete two Phase I RAs, two Phase II RAs, and one Phase III RA in FY04.
  • Transfer approximately 4929 acres to the U.S. Department of the Interior and 126 acres to local governments in FY04-FY05.
  • Complete one Phase IV RD in FY05.

There are no MMRP actions scheduled for FY04 or FY05.

Active Installation Cleanup

BRAC | BTAG | Guidance | Oversight
PBC | Program Management | Technical Assistance