[Federal Register Volume 71, Number 146 (Monday, July 31, 2006)]
[Rules and Regulations]
[Pages 43071-43073]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-6572]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 300

[EPA-HQ-SFUND-1987-0002; FRL-8204-2]


National Oil and Hazardous Substances Pollution Contingency Plan; 
National Priorities List

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of partial deletion of the Rocky Mountain Arsenal 
National Priorities List Site from the National Priorities List.

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SUMMARY: The Environmental Protection Agency (EPA) Region 8 announces 
the deletion of the Internal Parcel of the Rocky Mountain Arsenal 
National Priorities List (RMA/NPL) Site from the National Priorities 
List (NPL). All areas originally proposed for deletion (71 FR 24627), 
except for a three-acre area which encompasses the Rail Yard Treatment 
System, are being deleted (see map). The Rail Yard Treatment System is 
excluded from the Internal Parcel due to a delay in developing the 
Interim Construction Completion Report. With the Rail Yard area 
excluded, the Internal Parcel consists of 7,396 acres (11.5 square 
miles) of the On-Post Operable Unit of RMA. The NPL constitutes 
Appendix B of 40 CFR part 300, which is the National Oil and Hazardous 
Substances Pollution Contingency Plan (NCP), which EPA promulgated 
pursuant to section 105 of the Comprehensive Environmental Response, 
Compensation, and Liability Act (CERCLA), as amended. EPA and the State 
of Colorado, through the Colorado Department of Public Health and 
Environment (CDPHE), have determined that the Internal Parcel of the 
RMA/NPL Site poses no significant threat to public health or the 
environment and, therefore, no further remedial measures pursuant to 
CERCLA are appropriate.
    This partial deletion pertains to the surface media (soil, surface 
water, sediment), structures, and groundwater of the Internal Parcel of 
the On-Post OU of the RMA/NPL Site. The Internal Parcel includes 
groundwater that is east of E Street with the exception of a small area 
in the northwest corner of Section 6. The Rail Yard Treatment System 
and the rest of the On-Post OU, including groundwater below RMA that is 
west of E Street and the small area in the northwest corner of Section 
6, as well as the Off-Post OU will remain on the NPL. This partial 
deletion of the Internal Parcel will not change Appendix B of 40 CFR 
part 300, which was previously amended in January 2003 (68 FR 2699) to 
reflect that a partial deletion of 1.5 square miles from the RMA/NPL 
Site had occurred.

DATES: This partial deletion of the Internal Parcel is effective on 
July 31, 2006.

FOR FURTHER INFORMATION CONTACT: Ms. Jennifer Chergo, Community 
Involvement Coordinator (8OC), U.S. Environmental Protection Agency, 
Region 8, 999 18th Street, Suite 300, Denver, Colorado 80202-2466;

[[Page 43072]]

telephone number: 1-800-227-8917 or (303) 312-6601; fax number: 303-
312-6961; e-mail address: [email protected].

SUPPLEMENTARY INFORMATION: The Rocky Mountain Arsenal National 
Priorities List (RMA/NPL) Site is located in southern Adams County, 
Colorado and is comprised of two operable units (OU), the On-Post and 
Off-Post. The On-Post OU of the RMA/NPL Site encompasses 17.2 square 
miles (11,007 acres) approximately eight miles northeast of downtown 
Denver, Colorado. The Off-Post OU addresses contamination north and 
northwest of the RMA proper boundaries. The Internal Parcel consists of 
approximately 11.5 square miles (7,396 acres) of the On-Post OU of RMA 
in Commerce City, Colorado.
    This partial deletion pertains to the surface media (soil, surface 
water, sediment), structures, and groundwater of the Internal Parcel of 
the On-Post OU of the RMA/NPL Site. The Internal Parcel includes 
groundwater that is east of E Street with the exception of a small area 
in the northwest corner of Section 6. The rest of the On-Post OU, 
including groundwater below RMA that is west of E Street and the small 
area in the northwest corner of Section 6, and the Off-Post OU will 
remain on the NPL.
    On April 26, 2006, EPA published a Notice of Intent for Partial 
Deletion (NOIDp) in the Federal Register (71 FR 24627) and local 
newspapers which proposed to delete the Internal Parcel from the RMA/
NPL Site. EPA received comment letters from ninety-four organizations/
entities and individuals. Authors of six letters were opposed to the 
proposed partial deletion of the Internal Parcel. One of these letters 
requested postponement of the deletion stating that the 60-day review 
time was insufficient to review and resolve questions regarding 
characterization of the eastern portion of the Internal Parcel and 
their perception of unnecessary risk posed by deletion of the western 
portion of the Internal Parcel. Several commenters also questioned the 
``piece-meal'' approach to the Internal Parcel deletion.
    In our Responsiveness Summary, EPA described the CERCLA 
investigation process and how various areas of the Internal Parcel, 
including the eastern portion which includes the groundwater aquifer 
below a demolition range, were characterized. This process included 
file searches, ``desktop'' information (e.g., aerial photographs) 
searches, site reconnaissance, and collection of both soil and 
groundwater samples during the Remedial Investigation (RI). Soil 
samples were collected from burn pits and ordnance disposal areas, 
specific areas of concern to the commenters, during the RI. Explosive 
residue and Toxicity Characteristic Leaching Procedure (TCLP)-metals 
were addressed during pre-design studies for the Burial Trenches and 
Munitions (Testing) Soil Remediation Project. These studies showed that 
explosive residue and TCLP-metal concentrations were below risk-based 
regulatory levels. Considering these studies, the geology of the area, 
as well as the history of the disposal areas, there is no evidence of 
explosive or TCLP-metal soil contamination that could act as a source 
of groundwater contamination. The discovery of limited additional 
contamination at one area subsequent to the original excavation being 
completed demonstrates the multiple, sometimes overlapping, elements of 
the selected remedy that protect human health and the environment. 
These elements include excavation of known contaminated soil, further 
evaluation of ecological risks, and collection of confirmatory samples.
    EPA ensures that human health is protected from on-going remedial 
activities on the remaining NPL areas through effective control of 
project emissions, restricting visitor access, and implementation of 
the Site-Wide Air Quality Monitoring Program Plan, including monitoring 
of air emissions. There are two major project areas that involve 
disturbance of contaminated soil remaining in the NPL area. Visitors to 
the Refuge are restricted to areas located approximately one mile from 
the Lime Basin slurry wall project and approximately two miles from the 
Basin F projects. Air emissions are measured at the current fenceline 
and near the Visitor Center to verify that potential risks to visitors 
and the nearby communities are minimized. These requirements to protect 
human health will remain in place irrespective of the deletion of the 
Internal Parcel.
    EPA's responsiveness summary further explained how only areas which 
met the criteria of ``Responsible parties or other persons have 
implemented all appropriate response actions required'' (40 CFR 
300.425(e)(1)(i)) were considered for deletion. EPA's Partial Deletions 
Rule, published November 1, 1995, was intended to allow portions of a 
site or an OU that have been cleaned up to be available for productive 
use, especially where total site cleanup may take many years. This 
description accurately reflects the ongoing cleanup at the RMA/NPL 
Site, which is over 50 percent complete, i.e., ten years of the 
fifteen-year schedule have passed and 16 of the 31 remedy projects have 
been completed. Partial deletion of the Internal Parcel communicates to 
the public the successful implementation of the remedy and progress 
toward final cleanup. In addition, it helps the Army achieve its goal 
of transferring property and furthers the purposes of the RMA National 
Wildlife Refuge Act (1992). The Internal Parcel deletion, though 
described as ``piece-meal'' by the commenters, is consistent with other 
partial deletions that leave islands of an NPL site surrounded or 
abutted by deleted lands, e.g., Cecil Field, (68 FR 27746).
    The remaining eighty-eight letters supported proceeding with the 
Internal Parcel deletion based upon their confidence in the 
thoroughness of the cleanup activities conducted by the Department of 
the Army (Army) and Shell Oil Company (Shell). EPA agrees that 
completion of the remedy requirements as well as recent, site-wide 
studies adequately demonstrate that the Internal Parcel does not 
present a threat to the environment or human health and deletion of the 
Internal Parcel from the RMA/NPL Site is appropriate.
    EPA identifies sites that appear to present a significant risk to 
public health, welfare, or the environment and maintains the NPL as the 
list of those sites. Any site deleted from the NPL remains eligible for 
Fund-financed actions in the unlikely event that conditions at the site 
warrant such action. Section 300.425(e)(3) of the NCP states that Fund-
financed actions may be taken at sites deleted from the NPL. Deletion 
of a site from the NPL does not affect responsible party liability or 
impede Agency efforts to recover costs associated with response 
efforts.

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[GRAPHIC] [TIFF OMITTED] TR31JY06.000

List of Subjects in 40 CFR Part 300

    Environmental protection, Air pollution control, Chemicals, 
Hazardous substances, Hazardous waste, Intergovernmental relations, 
Penalties, Reporting and recordkeeping requirements, Superfund, Water 
pollution control, Water supply.

    Dated: July 24, 2006.
Robert E. Roberts,
Regional Administrator, Region 8.
[FR Doc. 06-6572 Filed 7-28-06; 8:45 am]
BILLING CODE 6560-50-C