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Superfund Program
Rocky Mountain Arsenal
Click here for an interactive map |
Site Type: Federal Facility City: Commerce City County: Adams Zip Code: 80022 EPA ID#: CO5210020769 |
The Army established the Rocky Mountain Arsenal (RMA) in 1942 to manufacture chemical weapons. After World War II, the Army leased parts of the Arsenal to private industry. The Army and private chemical manufacturers disposed of liquid wastes in basins and trenches, which leaked and contaminated ground water. Since 1982, the Army, Shell Oil, the State of Colorado and the Environmental Protection Agency (EPA) have been involved in enforcement and legal actions to ensure the cleanup of the Arsenal.
Site Description
RMA is located 10 miles northeast of downtown Denver, Colorado, adjacent to Commerce City and Brighton to the north, Montbello to the south, Denver International Airport to the east, and Commerce City to the west. Residential homes border the site to the north, south and west and residential and business development is rapidly growing in these areas.
RMA was created in 1942, at the height of World War II, when the Army purchased
17,000 acres of land to manufacture chemical weapons such as mustard gas and
white phosphorus. Private industry was encouraged to lease facilities at RMA
after the war to foster economic growth in the area, offset operational costs,
and maintain facilities for national security. Under the lease program, Julius
Hyman and Company began producing pesticides in 1946. In 1952, Shell Chemical
Company acquired Julius Hyman and Company and continued to produce agricultural
pesticides on-site until 1982. Common industrial and waste disposal practices
used by the Army and Shell during these years resulted in the contamination
of structures, soil, surface water, sediment, and groundwater.
In 1984, the Army began a systematic investigation of site contamination in
accordance with the Comprehensive Environmental Response Compensation and Liability
Act (CERCLA) of 1980 and as a result, the site was placed on the National Priorities
List (NPL) in 1987. The NPL is a list of the nation's most hazardous sites,
commonly referred to as Superfund Sites. As required by CERCLA, the Army conducted
a Remedial Investigation/Feasibility Study (RI/FS) to determine the nature and
extent of contamination and to develop and evaluate remedial alternatives.
In the late 1980's, the Army, EPA, and Shell signed the Federal Facility Agreement (FFA) that specified the process by which decisions will be made for the cleanup of RMA, and established certain cleanup goals. The FFA provided a framework under which the parties agreed to conduct Interim Response Actions (IRA) on specific contamination problems in advance of the final cleanup plan.
The FFA ultimately led to the signing of two Records of Decision (ROD). The Off-Post ROD was signed December 19, 1995 and the On-Post ROD was signed June 11, 1996. The RODs provide the framework, purpose, and overall rationale for the remediation actions that must be accomplished at the site. The Army, EPA, and the Colorado Department of Public Health and Environment (CDPHE) signed both RODs. The U.S. Fish and Wildlife Service (USFWS) and Shell concurred with the on-post ROD.
The Army, serving as the lead agency, and Shell are implementing the remedy selected in tlhe RODs that includes 31 projects for soils, structures, and the treatment of groundwater contaminants. The EPA, CDPHE, and Tri-County Health Department (TCHD) are conducting regulatory oversight. The Army selected Foster Wheeler Environmental Corporation (FWEC), now TetraTech ECI, in 1997 to serve as the Program Management Contractor. FWEC selects and manages the subcontractors needed to perform the remediation work.
In January 1989, the USFWS established a field office at RMA to manage wildlife, particularly bald eagles and ferruginous hawks. An existing partnership between the two entities enables the Army and the USFWS to manage the wildlife resources and public use on RMA, while the Army continues its cleanup program. In October 1992, the U.S. Congress enacted a bill designating approximately 16,000 acres of RMA as one of the nation's largest urban wildlife refuges. The bill allows the transfer of responsibility from the Army to the USFWS once the cleanup process is complete. To date, EPA has deleted nearly 14,000 acres of land at the Rocky Mountain Arsenal because all required cleanup activities have been completed. Of that, more than 12,000 acres have been transferred from the Department of Defense to the U.S. Fish & Wildlife Service to become part of the National Wildlife Refuge System.
Following the signing of the ROD, the site has been actively undergoing 31
cleanup projects involving soil, structure, and groundwater contamination. All
remediation activities are expected to be finished by 2011, depending upon funding
from Congress.
Site Risk
Studies have identified contamination in buildings, soil, sediments, sewers, surface water, and groundwater at RMA. Contaminants have also been detected in wildlife living in some of the more contaminated areas of the Arsenal.
Most contaminated soils are located in the central six square miles of the Arsenal. Most of the health risks posed by the site are from: aldrin, dieldrin, dibromochloro-propane (DBCP), and arsenic. Aldrin is a pesticide that breaks down to dieldrin. Both chemicals are stored in the body and affect the central nervous system and liver. DBCP is also a pesticide, but it is not stored in the body. DBCP can affect the testes, kidneys, liver, respiratory system, central nervous system and blood cells. Arsenic is a naturally occurring element. It can cause cancer in humans.
| Media Affected | Contaminants | Source of Contamination |
| Soil, surface water and groundwater | Aldrin, dieldrin, dibromochloro-propane (DBCP), arsenic | GB nerve agent and pesticide manufacturing |
Cleanup Progress
Current Cleanup Projects
Basin F Principal Threat Soils: The Basin F Principal Threat Soils are comprised of highly contaminated soils that pose a significant risk to human health and the environment. The 100 percent design of the former Basin F soils excavation project was finalized in February 2007 and construction work began in June 2007. The project is expected to last through the Spring of 2008.
Shell Disposal Trenches Cover: The Shell Disposal Trenches Cover is currently being constructed and is the first of six Resource Conservation & Recovery Act (RCRA) equivalent covers to being construction at the Arsenal. RCRA-equivalent covers are designed to ensure that no precipitation migrates through the contaminated waste below.
Upcoming Cleanup Projects
Integrated Cover System: The Integrated Cover System Design will provide for Resource Conservation and Recovery Act (RCRA) - equivalent covers at Basin A, Complex Army Trenches, Lime Basins, and South Plants Central Processing Area. These RCRA-equivalent covers are designed to ensure that no precipitation migrates through the contaminated waste consolidated below. The design will also provide for the construction of a 3-foot cover over South Plants, 1-foot backfill at South Plants, and a 2-foot cover at Shell Disposal Trenches. Construction materials will include crushed concrete currently stockpiled on the former Stapleton Airport property. Construction began in June 2007 and is expected to finish in Sept. 2010.
Section 36 Lime Basins Slurry Wall Installation: The Slurry Wall is meant to isolate the underground contaminated waste from the surrounding groundwater and to prevent future migration of contaminants. Slurry Wall installation is scheduled to start September 2007 and be completed in January 2008.
Recently Completed Projects
Basin F Wastepile: The Basin F Wastepile consisted of contaminated soil dredged from and beneath the Basin F disposal basin. The Wastepile is being excavated and taken to the Enhanced Triple-Lined Landfill. This project began in April 2006 and was completed in summer 2007.
Construction of the Hazardous Waste Double-Lined Landfill (HWL): The HWL, located in the central area of the site, encompasses approximately 24 acres and has the capacity to hold 1.8 million compacted cubic yards of waste. Phase I of the HWL was constructed in 1998, and it began accepting waste in 1999. Phase II of the HWL was constructed in November 2000 and began accepting waste in January 2001. Both phases are comprised of multiple layers of soil, clay and plastic liners. It also includes a leachate management system, a wastewater treatment system, a surface water management system, and a future soil cover to isolate waste from groundwater and other environmental pathways. The HWL was filled to capacity in 2006. The cover installation began in fall 2006 and is expected to be completed in November 2008.
Existing Sanitary Landfills: The Sanitary Landfill remediation project consists of seven sites that include sanitary landfills, trenches and surface disposal areas previously used by the Army and its contractors as trash disposal sites. These sites are located in various areas on RMA and primarily contain trash, construction debris, wood, paper, asbestos and metal piping. Excavated material was taken to the HWL and the Basin A consolidation area. This project was completed in 2005.
2005 Lime Basins and Basin F Principal Threat Soil Remediation ROD Amendment: This provided for a fundamental change at lime basins from excavation/disposal to isolation-in-place with a slurry wall and RCRA-equivalent cover. At former Basin F, this provided for a change from solidification of principal threat soils to excavation of those soils and disposal in the Enhanced Hazardous Waste Landfill. For the Basin F exterior, this provides for the reduction in the size of Basin F, removal of some Biota and Human Health Exceedence soils, and other related activities.
Constructing the Enhanced Hazardous Waste Triple-Lined Landfill: An enhanced or triple-lined landfill was constructed south of the existing double-lined landfill and will be comprised of two waste containment cells. Both cells are being constructed similar to the double-lined cells with multiple layers of clay and plastic liners, but with an additional layer for enhancement. The landfill began accepting waste in 2006.
Miscellaneous Structures Phase I and II: Administrative buildings, old bunkers and warehouses no longer needed to support the cleanup effort were demolished. Phase I demolished 102 structures; and Phase II demolished 22 structures. The debris was taken to the HWL and the Basin A consolidation area. Both phases were completed by February 2004.
Hex Pit: Contaminated materials and associated soil in the Hex Pit were excavated and taken to the HWL. This project was completed in February 2004.
Section 36 Soil Remediation: Contaminated soil, chemical sewers, and munition debris are being excavated and taken to the HWL and the Basin A consolidation area. Munitions from the munitions test area were removed and destroyed on-site. This project was completed in 2004. Hex Pit Soil Remediation Project ROD Amendment: This provided for a fundamental technology change from thermal treatment to excavation and disposal.
Basin F and Basin F Exterior Soil Remediation Project - Part I: Contaminated soil was excavated and taken to the HWL and the Basin A consolidation area. This project was completed in 2003.
Burial Trenches Part I and II: Contaminated soil, asbestos, burned debris and non-explosive munition debris were removed and taken to the HWL and the Basin A consolidation area. Munitions were removed and destroyed on-site. Both phases were completed by May 2003.
North Plants and South Plants Structures Demolition: Approximately 260 buildings once used to manufacture chemical agent, fill munitions and blend rocket fuel were demolished. Efforts involved demolishing buildings and their foundations, removing contaminated soil, decontaminating and destroying equipment once used to manufacture and fill chemical weapons, bringing in clean fill soil, and site grading to return the land to its original character. Contaminated material was taken to the HWL and the Basin A consolidation area. South Plants demolition was completed in 2001. North Plants demolition was completed in 2003.
Secondary Basins Part I and II: Contaminated soil was excavated and taken to the Basin A consolidation area. This project was completed in 2003.
Section 35 Soil Remediation: Contaminated surface soil and removal of two small sections of sewer lines left from a previous chemical sewer project were excavated and taken to the HWL and the Basin A consolidation area. This project was completed in 2003.
South Plants Balance of Areas and Central Processing Area Soil Remediation Project: Contaminated soil and chemical sewers from previous manufacturing, storage and spills of chemicals in the South Plants area was excavated and taken to the HWL and the Basin A consolidation area. This project was completed in 2003.
Community Involvement
In the 1950s, residents living north and northwest of the site began to take interest in RMA when crop damage was noticed on nearby farms. The Army began to study the groundwater flowing off the site and detected contamination. In the 1960s, the Army disposed of liquid chemical waste from the Basin F project into a 12,045-foot deep injection well after the Basin F liner began to leak. Some community members and geoscientists believed that the Army's deep injection well might have caused earthquakes in the Denver area. Although this was never proven, the Army stopped using the well in 1966 and sealed it in 1985.In the mid 1980s, community interest peaked again with the Army's initiation of 14 Interim Remedial Actions (IRAs) for air, soil, water and structures. These response actions focused on immediate cleanup needs while the site was undergoing extensive study.
In the late 1980s, one of the site's 14 IRAs generated strong community interest, concern and involvement. The Basin F IRA involved the transfer of four million gallons of Basin F liquid to three 1.3 million gallon holding tanks and approximately 6.5 million gallons to a double-lined holding pond. The project also removed 600,000 cubic yards of sludge, soil, and liner material from in and under Basin F and placed it in the Basin F Wastepile. The project encountered several obstacles including heavy rainfall. The excess rainfall increased the volume of the Basin F liquid and raised the need for a second double-lined holding pond. Once the liquid was drained from the holding basin, the method used to dry the sludge so that it could be placed into the Wastepile created strong odors resulting in community concern and frustration. Several public meetings were held. Air purifiers were distributed to affected residents to alleviate odors. Local and federal government agencies studied the odors and determined there were no acute health impacts to residents.
In the early to mid 1990s, RMA had to decide how best to destroy the Basin F liquid waste being stored in holding tanks. After community outreach and input including a series of public meetings and weekend workshops, the Army, Shell and the Service along with EPA, CDPHE and the Tri-County Health Department decided to incinerate the liquid waste by means of the submerged quench incinerator. The incinerator began processing the Basin F liquid in 1993.
Community involvement continued throughout the 1990s. Through public meetings, publications, videos, and other communication tools, the community was encouraged to be involved in the decision making process that would ultimately lead to the ROD. The ROD outlines RMA's final environmental cleanup plans. The RMA Restoration Advisory Board (RAB) and Site Specific Advisory Board (SSAB) were comprised of community members and were formed with the purpose of informing and answering community questions about the ROD as well as listening to concerns and receiving input from the community. The Department of Defense recognizes the RAB as the official RMA citizen advisory group. The RAB is comprised of community members from the affected neighboring areas, RVO, and regulatory agencies. The board meeting is held at RMA on the fourth Thursday of the month or as needed. The SSAB is comprised of community members interested in RMA. The advisory boards are still in place today but have changed focus from pre-ROD to post-ROD activities such as engineering designs and implementation of the 31 cleanup projects.
The ROD stipulated a Medical Monitoring Advisory Group (MMAG) be formed to evaluate information concerning exposure pathways from the cleanup, to identify and recommend appropriate public health actions and to communicate this information to the community. CDPHE formed the MMAG in December 1995 according to the ROD's provision and in response to citizen concerns that public health protections play a key role in RMA's cleanup program. The MMAG, comprised of community members from the affected neighboring areas, Shell, USFWS and regulatory agencies, focused on human health monitoring, environmental monitoring, emergency preparedness, and public involvement and education. The MMAG developed recommendations to monitor for any impact on community health during the environmental cleanup, and ensure information about the cleanup and the program is available to the communities. As part of the MMAG's recommendations, the group called for the creation of a Medical Monitoring Program Citizen Advisory Board (CAB). The CAB serves as a communication link to the communities, ensures the MMAG's recommendations are carried forward and makes recommendations to the State Health Department on program implementation. The CAB meets two times per year or as needed.
Telephone surveys were conducted in 1998 to evaluate cleanup information and wildlife-related activities with 400 residents living in Brighton/Henderson, Commerce City and Montbello. The survey included questions about community issues among RMA neighbors, sources for local community news, knowledge of RMA's environmental cleanup and wildlife-related activities, preferences for RMA information and participation, and interest and preferences for RMA public meetings.
In 2000, another surge of public interest occurred with the recovery of 10 sarin-filled (nerve gas) bomblets. The bomblets were recovered in an old scrap yard area located in the central portion of the site. Because of RMA's proximity to neighboring communities and downtown Denver, there was high media and public interest about the bomblets and the disposal option selected. Over the course of several months, experts from the federal and state governments, including high-ranking Army officials, Colorado Governor Bill Owens, Senator Wayne Allard and Representative Diana DeGette, worked together to determine the best destruction method for the bomblets that would be protective of the community, RMA workers and the environment. A variety of community outreach tools were implemented including:
- Communicating with elected officials and the media (at times, on a daily basis);
- Distributing door-to-door information bulletins (in English and Spanish);
- Providing 5,000 flyers to local businesses for distribution;
- Recording seven automated pre-recorded phone messages with critical updates that reached more than 31,000 neighbors;
- Providing email updates to nearly 300 residents;
- Updating RMA's web site daily;
- Hosting five off-site public meetings (with a Spanish interpreter available for the Spanish-speaking community) to explain the destruction options and to provide a forum for community input; and
- Establishing a community information hotline for residents to receive more
information or to talk to an RMA representative.
Site Documents
Site Fact Sheet (PDF, 735K)
Five-Year Review, 2007 (PDF, 490 pp, 55MB)
Draft - Final Five-Year Review 2005
Five-Year Review, 1992 (PDF, 68 pp, 266K)
Five-Year Review, 2001 (PDF, 152 pp, 1.92M)
Western Tier Parcel Decision
Selected Perimeter Area & Surface Area DeletionInternal Parcel Proposed Partial Deletion
- Federal Register Notice of Intent to Delete, July 2006
- Proposed partial deletion fact sheet PDF (PDF, 8 pages, 426 kB)
- Internal partial map (PDF, 100 kB)
Record of Decision (ROD) Changes:
Recent Fact Sheets:
- RCRA-Equivalent Covers Fact Sheet
- LWTS Fact Sheet
Land Deletions from the National Priorities List (Superfund Sites)
- Selected Perimeter and Surface Area Deletion: In 2004, EPA deleted
approximately 5,000 acres of Rocky Mountain Arsenal land from the National
Priorities List because all required cleanup activities in this area were
complete. This land was then transferred from the U.S. Army to the U.S.
Fish and Wildlife Service to create the Rocky Mountain Arsenal Wildlife
Refuge.
- Western Tier Parcel Deletion: In 2004, EPA also deleted nearly
1,000 acres of Rocky Mountain Arsenal land from the National Priorities
List because all required cleanup activities were complete in this area.
This land was then transferred from the U.S. Army to Commerce City to become
the Prairie Gateway development.
- Internal Parcel Deletion: In 2006, EPA deleted more than 7,000
acres of Rocky Mountain Arsenal land from the National Priorities List because
all required cleanup activities were complete in this area. This land was
then transferred from the U.S. Army to the U.S. Fish and Wildlife Service
to augment the Rocky Mountain Arsenal National Wildlife Refuge.
Contacts
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EPA Jennifer Chergo |
Colorado Warren Smith
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| View Documents at: Joint Administrative Records Document Facility Building 129, Room 2024 Commerce City, Colorado 80022-1748 |
U.S. Army Rocky Mountain Arsenal Web site |
