In the mid-1980s, the Army, the U.S. Environmental Protection Agency (EPA), the Colorado Department of Public Health and Environment (CDPHE) and Shell Oil Company agreed that certain interim response actions (IRAs) should be undertaken in accordance with the FFA. These actions, reported to the U.S. District Court for the District of Colorado on June 5, 1987, were designed to remove threats to the environment while remaining consistent with any long-term, comprehensive cleanup at the Arsenal. The following is a list of the IRAs, which are in various stages of operation or completion:
 Offpost Intercept and Treatment System (North Plume Group) Construction of this facility, located beyond the Arsenal's northern
boundary at Peoria Street and 96th Avenue, began in November 1991 where
full-scale operations began in June 1993. The major components of this
action are the removal of contaminated groundwater north of the RMA boundary,
followed by treatment of the extracted groundwater, and finally recharging
the treated groundwater using a series of reinjection wells. The reinjected
groundwater meets or exceeds applicable state and federal standards for
groundwater. The Offpost Record of Decision, which was finalized December
19, 1995, determined that this facility would be improved and monitored
as needed. |
 Improvement of the North and Northwest Boundary Groundwater Intercept and Treatment Systems The scope of this project was twofold: to implement process improvements
to the North Boundary Groundwater Intercept and Treatment System and to
construct groundwater recharge trenches to increase the reinjection rate
of treated groundwater. This system treated and recharged 135 million gallons
during 1995. Assessment of the Northwest Boundary Groundwater Intercept
and Treatment System and implementation of extensions to the northeast
and southwest have been completed. This was accomplished to prevent any
alluvial groundwater from bypassing the system. In 1995, the Northwest
Boundary System treated and reinjected approximately 545 million gallons
of water. |
 Basin F Neck Groundwater Intercept and Treatment System This IRA consists of a one-well pretreatment system and has been fully
operational since 1990. The water flowing north of Basin F is caught and
pretreated prior to being integrated with the water processed at the Basin
A Neck for recharge into that system. This process makes the boundary treatment
systems more efficient by treating the groundwater closer to the source. |
 Basin A Neck Groundwater Intercept and Treatment System This project called for the design and construction of an alluvial (or
shallow) groundwater intercept and treatment system in the Basin A Neck
area. As with the Basin F Neck IRA, this system treats groundwater more
efficiently by capturing it closer to the source. Site preparation for
Basin A Neck began in November 1989 and became fully operational in July
1990. The system treated approximately 7.3 million gallons in 1995. |
 Closure of Abandoned Wells on the Arsenal This action consisted of sampling, plugging and closing over 350 wells
that were not part of the ongoing groundwater monitoring program or were
not suitable for inclusion in the future monitoring program. |
 Basin F Liquid, Sludges and Soils Remediation This IRA called for the cleanup of contaminated liquids, sludges, and
soils from and under Basin F. The Basin F liquid was removed to temporary
storage in three steel tanks and a holding pond, known as Pond A. The Submerged
Quench Incinerator (SQI) was built to efficiently process the Basin F liquid
and became fully operational in July 1993. By July 1995, the SQI had destroyed
all 11 million gallons of Basin F liquid. The soils and sludges from the
basin were placed in an approved wastepile which was equipped with a series
of sumps to drain the leachate (or percolated liquid) and move it through
pipelines to the holding pond. The Onpost Proposed Plan for the Cleanup
of Rocky Mountain Arsenal, released in October 1995, calls for the removal
of the Basin F wastepile to another onsite landfill. |
 Building 1727 Sump Liquid This action provided for containment and treatment of contaminated liquid in the Building 1727 sump to mitigate any remaining threat of release of liquids from this sump. This liquid is now treated at the CERCLA Wastewater Treatment System (see #13) |
 Closure of the Hydrazine Facility This 10-acre production site was constructed in 1959 as a rocket fuel
blending facility. The scope of this IRA was completed in two phases. The
primary phase focused on the treatment and disposal of pretreated liquids
in tanks used for storage of production waste. The pretreated liquids were
transferred to Pond A in January 1992 to await proper disposal. The secondary
phase focused on dismantling and disposal of all above ground and below
ground structures associated with the hydrazine facility. The demolition
and disposal of all remaining structures was completed in September 1992. |
 Fugitive Dust Control This IRA is sometimes referred to as Dust Abatement. It pertains to
the regular application of a spray to unvegetated areas of Basin A to keep
the soils in place and mitigate the release of wind-blown, contaminated
dust. |
 Sanitary Sewer Remediation This action consisted of plugging certain portions of the sewer line
to ensure safety at the Arsenal and eliminate the sanitary sewers as a
potential conduit for contaminant flow. This action was completed in September
1992. |
 Asbestos Removal This IRA sets up the Army's ongoing survey of friable (i.e., flaking)
asbestos and the prompt removal/disposal of it (if the survey indicates
a potential for human exposure). As of November 1995 more than 3,127 tons
of asbestos had been removed from pipelines, tanks, and buildings since
1987. |
 Remediation of Other Contamination Sources This action consisted of assessment, selection, and implementation of
IRAs for the Section 36 Trenches, the Section 36 Lime Pits, the M-1 Settling
Basins, the Motorpool Area, and the Railroad Holding Track in the Rail
Classification Yard, as well as the South Tank Farm Plume area which was
added later by the Parties and the state. Actions at all of these sites
have been completed. |
 Pre-treatment of CERCLA Liquid Wastes CERCLA Wastewater Treatment Facility
This project involved selecting and implementing a new treatment system using seven different technologies to treat wastewater. This IRA was later expanded to include the management and coordination of waste storage and disposal, and PCB removal. |
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