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Hazardous Materials and Waste Management Division
Rocky Mountain Arsenal
This site is one of the "Superfund" hazardous
waste sites in Colorado. A site qualifies for the National Priorities List
(NPL or Superfund list) when the
U.S. Environmental Protection Agency (EPA) determines there is a release or threatened
release of hazardous substances that may endanger public health, welfare or the
environment. The US Army is the lead agency for the Rocky Mountain
Arsenal remediation because the site is a federally-owned
facility.
For questions or comments on the Rocky
Mountain Arsenal Site, contact:
Susan Newton
State Project Manager
(303) 692-3321
(888) 569-1831 ext 3321 toll-free
Warren Smith
State Community Involvement Coordinator
(303) 692-3373
(888) 569-1831 ext 3373 toll-free
or
Jennifer Chirgo, EPA
Community Involvement
(303) 312-6601
Site Summary
Location
The Rocky Mountain Arsenal (the
Arsenal) is located north of the former Stapleton
Airport and west of Denver International Airport. Residential and
commercial property are located to the south and west, with
residential, commercial and agricultural land to the north.
Henderson is 4 miles to the northwest, Brighton is 6 miles north, and
Barr Lake State Park is about 5 miles northeast.
History
The U.S government acquired the Arsenal
land in 1942
to manufacture chemical warfare agents and incendiary munitions for
use in World War II. Following the war and through the early 1980s,
the facilities continued to be used by the Army. During the 1950s and
into the 1960s, obsolete and deteriorating munitions were destroyed
onsite. From 1950 to 1952, the Army constructed the North Plants
complex to manufacture the nerve agent GB, also called Sarin. Rocket
fuel was blended onsite for the Titan and Delta missile operations.
In an effort to foster economic growth in the area and maintain the
facilities for national security, private companies were encouraged to lease facilities
beginning in the mid-1940s. Shell Oil Company manufactured agricultural pesticides in the
South Plants complex from 1952 through 1982.
Manufacturing and waste disposal practices used during these years
resulted in soil, surface water, sediment, ground water and structures contamination.
Solid and liquid wastes were disposed of in trenches, burn pits and unlined basins.
Contaminated ground water was first discovered north of the Arsenal in the mid-1950s, when
crop damage was noted on farms. New liquid waste disposal methods were employed to try to
prevent further contamination, including a lined basin called Basin F and deep well
injection, but these were unsuccessful. The Army and Shell Oil Company began conducting
detailed site investigations in the 1970s to define the extent of contamination. All
manufacturing activities ended in 1982.
Fourteen interim response actions were undertaken to solve immediate
environmental problems while the final cleanup solutions were being determined. They
included systems to capture and treat contaminated ground water before it flows off the
site. Another system north of the Arsenal treats contaminated water that has already moved
offsite. Other interim response actions included removal and treatment of 10.5 million
gallons of Basin F liquids, closure of a well more than two miles deep, and removal of
76,000 drums of hazardous salts.
Environmental laws and regulations govern the
Arsenal cleanup
activities. A federal law called the Comprehensive Environmental Response and Liability
Act, commonly known as Superfund, establishes procedures that must be followed during
environmental cleanup programs. The Rocky Mountain Arsenal was placed on the National
Priorities List of Superfund sites in July 1987. Some Arsenal cleanup activities are
governed by another federal environmental law called the Resource Conservation and
Recovery Act (RCRA). The Colorado Department of Public Health and Environment
(the Department) has been
delegated authority to oversee compliance with this law in Colorado.
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Chemicals
More than 600 chemicals have been used
or manufactured at the Arsenal, including volatile organic compounds (VOCs), heavy metals, pesticides, and
diisopropyl methylphosphonate (DIMP), a chemical unique to the Army's manufacture of nerve
gas. Four chemicals (aldrin, dieldrin, dibromochloropropane and arsenic) cause most of the
potential human health risks.
Exposure
The potential human exposure pathways
include ingestion, skin absorption and inhalation from contaminated soils, ground water
and air. Current potential exposure is greatly reduced through site access and
institutional controls, an alternate drinking water supply for neighboring residents whose
wells have been affected by Arsenal contaminants, and careful planning of the cleanup project.
Public access to the site is strictly controlled and workers follow prudent health and
safety procedures. Colorado State University and the Colorado Department of Public Health and Environment have conducted health
investigations in the communities around the Arsenal.
Contamination was detected in soil, ditches, stream and lakebed
sediments, sewers, ground water, surface water, wildlife and structures.
The contaminated areas onsite included approximately 3000 acres of soil,
15 groundwater plumes and 798 structures. The most highly contaminated sites are concentrated in the central six
sections, or square miles, of the Arsenal where the former manufacturing and disposal areas
are located. The primary contaminants found in soil and groundwater in
these areas are organochlorine pesticides, solvents, metals, and
chemical warfare agent by-products. In addition, contamination has been detected in some wildlife.
The portion of the Rocky Mountain Arsenal cleanup that will require
the movement and disturbance of contaminated material is nearly
complete. The contaminated soils cleanup phase of the process is
expected to be complete by early 2008.
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The U.S. Army has the
lead role in remediation of the two Arsenal Operable Units, off-post and
on-post. Shell Oil
Company shares in the costs and implementation of the cleanup actions. The EPA, Colorado Department of Public Health and Environment and
Tri-County Health Department provide regulatory oversight. Two Records of Decision
(RODs)
were signed and describe the required cleanup actions. The Off-post Record
of Decision was finalized in
December 1995 and its requirements consist of actions for off site groundwater and soil. A
Record of Decision for the on-post operable unit cleanup was signed in June 1996 and
describes the cleanup plan for soils, groundwater and structures within
the approximately 27-square mile on-post Operable Unit. These field activities
began in the fall of 1997 and significant portions of the cleanup have already been
accomplished.
The On-post Record of Decision includes provisions for a permanent water supply for
off-post residents affected by Arsenal groundwater contamination, replacement water for South
Adams County Water and Sanitation District and a medical monitoring program to
monitor the success of exposure prevention efforts during the
environmental cleanup. Other cleanup actions include:
Soil:
-
Construct double and triple lined on-post hazardous waste landfills.
-
Excavate, solidify and dispose of 26,000 cubic yards
of buried
M-1 Pit waste in the landfill.
-
Excavate and dispose of 600,000
cubic yards Basin F waste pile contaminated
soil in the triple-lined landfill.
-
Excavate and dispose of more than one million cubic yards of
contaminated soil from various locations on the Arsenal into the landfill.
-
Excavate and dispose of 165,000
cubic yards of former Basin F Principal Threat waste in the
triple-lined landfill.
-
Excavate and dispose of 8000
cubic yards of Hex Pit waste in the triple-lined landfill.
-
Destroy offsite (or detonate onsite if unstable) any identified
unexploded ordnance. Excavate and dispose of unexploded ordnance debris and associated
soil in the landfill.
-
Install slurry walls and RCRA-equivalent soil covers for the Army
Complex and Shell disposal trenches and the Lime Basins where contamination will be left in place.
-
Construct a RCRA-equivalent soil cover over the former Basin F site.
Construct soil covers over Basin A, South Plants Central Processing Area, Secondary
Basins, North Plants, South Plants Balance of Areas and Section 36 Balance of Areas.
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Excavate 1.5 million cubic yards of soil that may pose a risk to
wildlife for use as fill under the covers or in the Basin A Consolidation Area.
-
Monitor excavated soil associated with chemical agent manufacturing
and treat, if necessary.
Water:
-
Continue operation of existing on-post
Arsenal groundwater treatment
systems until water quality goals are achieved. The off-post groundwater treatment system
will continue to operate under Off-post Record of Decision requirements.
-
Install a new groundwater treatment system in the northeast corner of
Section 36.
-
Treat NDMA (N-nitrosodimethylamine) contamination in groundwater at
the North Boundary Containment system to achieve water quality goals.
Structures:
-
Demolish approximately 530 structures and 250 electrical substations
and salvage metals where appropriate.
-
Dispose of demolition debris with significant contamination,
polychlorinated biphenyls, or from chemical agent production areas in the
on-post hazardous
waste landfill.
-
Dispose of some less contaminated structural debris in the Basin A
Consolidation Area.
Additional:
-
Restrict Arsenal land use and access. The 1992 Rocky Mountain Arsenal
National Wildlife Refuge Act and the Federal Facility Agreement restrict future land use
and prohibit certain activities such as agriculture, residential development, use of
on-post groundwater as a drinking source, and consumption of fish and game taken at the
Arsenal. Long-term management will include access restriction for soil covers and landfills to
ensure integrity of the containment systems.
-
Refine areas of soil and lake sediments requiring cleanup action for
protection of wildlife.
As portions of the cleanup are
completed, this property becomes part of the National Wildlife Refuge system and
is transferred to the US Department of
Interior. In 2004, 5000 acres along the perimeter of the site were
deleted from the National Priorities List of Superfund sites to
establish the National Wildlife Refuge. In 2006, 7,126 additional
acres were transferred. Eventually, most of the land area will
belong to the US Fish and Wildlife Service and the Army will retain
areas where hazardous wastes are managed, such as the
landfill and soil covers. Site reviews will be conducted every five years to make sure the
cleanup remedy is still effective. The US Fish and Wildlife Service is responsible for
managing Arsenal wildlife and habitat.
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The Rocky Mountain Arsenal On-post Record of Decision directed that a medical
monitoring program be instituted that would respond effectively to Arsenal-related health
concerns of the surrounding communities during the soil cleanup. The Colorado Department
of Public Health and Environment has the lead role in the administration of this program.
The medical monitoring program serves the communities of Commerce City,
Montbello,
Henderson and Green Valley Ranch.
The Record of Decision also directed that a
Medical Monitoring Advisory Group (the Advisory Group) be formed to recommend appropriate program components. The
Advisory Group, formed in 1995,
consisted of a diverse panel of community members, physicians, nurses, scientists, state
and local health officials and representatives from the EPA, Army, Shell and the US Fish
and Wildlife Service. The Advisory Group focused program recommendations on four key performance areas:
baseline health assessment and human health monitoring, environmental monitoring,
emergency preparedness and public involvement and education.
The Advisory Group completed its work in October 1998 and submitted a final
report to the Colorado Department of Public Health and Environment consisting of twelve recommendations.
The Department formally accepted all twelve
recommendations developed by the Advisory Group and began program implementation. These
recommendations include systematic evaluation of air quality data and its public health
significance, a process for selecting appropriate public health actions, systems to track
birth defects and cancer rates in the neighborhoods around the Arsenal, improvements to the
Arsenal air and odor monitoring programs, improvements to emergency response programs, health
professional education and public involvement and education.
The Advisory Group recommended that citizen involvement continue during
program implementation. A Citizen Advisory Board (the Advisory Board) was formed in 1999. The
Advisory Board meets annually and is responsible for making recommendations to improve the program.
If you would like more information about the Rocky Mountain Arsenal
or the medical monitoring program, contact
Warren Smith at (303) 692-3373.
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EPA Rocky Mountain
Arsenal Web Site - exit to EPA
Rocky Mountain Arsenal - Medical
Monitoring Program
Agency
for Toxic Substances and Disease Registry (ATSDR) Public Health
Assessment - exit to ATSDR
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