Document ID: EPA-HQ-SFUND-1990-0011-0002
Agency: epa
Document Type: Proposed Rule
Title: National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List; Notice of intent for partial deletion of the Ellsworth Air Force Base Site from the National Priorities List
Posted Date: 2006-06-28T11:45:08Z

[Federal Register: June 28, 2006 (Volume 71, Number 124)]
[Proposed Rules]               
[Page 36736-36741]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr28jn06-37]                         

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 300

[EPA-HQ-SFUND-1990-0011; FRL-8188-9]

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

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of intent for partial deletion of the Ellsworth Air 
Force Base Site from the National Priorities List.

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SUMMARY: The Environmental Protection Agency, Region 8 (EPA) announces 
its intent to delete portions of the Ellsworth Air Force Base (AFB) 
Site located in Meade and Pennington Counties, South Dakota, from the 
National Priorities List (NPL) and requests public comment on this 
action. The NPL constitutes Appendix B to the National Oil and 
Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, 
which EPA promulgated pursuant to Section 105 of the Comprehensive 
Environmental Response, Compensation, and Liability Act (CERCLA).
    The EPA has determined, with the concurrence of the State of South 
Dakota through the Department of Environment and Natural Resources 
(SDDENR) that for the parcels proposed for deletion, all appropriate 
actions under CERCLA have been implemented to protect human health, 
welfare and the environment and no further response action by 
responsible parties is appropriate. This partial deletion pertains to 
surface soil, unsaturated subsurface soil, surface water, and sediments 
at Operable Units 2, 3, 4, 5, 6, 7, 8, 9, 10 and 12, and excludes the 
ground water medium at these parcels. The ground water medium at the 
Ellsworth AFB Site (OU-11, Basewide Ground Water), and the soil medium 
(surface and unsaturated subsurface soils) at OU-1, Fire Protection 
Training Area, will remain on the NPL and response activities will 
continue for those OUs. Two additional areas not associated with an 
operable unit, the Gateway Lake Ash Study Area and the Pride Hangar 
Study Area, are currently under investigation and are also not part of 
this partial deletion.

DATES: Comments concerning this proposed partial deletion may be 
submitted on or before July 28, 2006.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
SFUND-1990-0011, by one of the following methods:
     http://www.regulations.gov: Follow the on-line 

instructions for submitting comments.
     E-mail: dalton.john@epamail.epa.gov.
     Fax: 303-312-6961.
     Mail: Mr. John Dalton, Community Involvement Coordinator 
(8OC), U.S. EPA, Region 8, 999 18th Street, Suite 300, Denver, CO 
80202-2466.
     Hand Delivery: 999 18th Street, Suite 300, Denver, CO 
80202-2466.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-SFUND-
1990-0011. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
http://www.regulations.gov, including any personal information 

provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site 

is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through http://www.regulations.gov, your e-mail address will be 

automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses.
    Docket: All documents in the docket are listed in the http://www.regulations.gov
 index. Although listed in the index, some 

information is not publicly available, e.g., CBI or other

[[Page 36737]]

information whose disclosure is restricted by statute. Certain other 
material, such as copyrighted material, will be publicly available only 
in hard copy. Publicly available docket materials are available either 
electronically in http://www.regulations.gov or in hard copy at the 

EAFB Information Repository located at the Rapid City Public Library 
and at the Ellsworth AFB Holbrook Library. The Rapid City Library is 
located at 610 Quincy Street, Rapid City, SD 57701. For hours of 
operation, call (605) 394-4171. Holbrook Library is located at 2650 
Doolittle Dr. Ellsworth AFB, SD 57706, between the Base commissary and 
the Base Theater. For hours of operation, call (605) 385-1686.
    All CERCLA and Environmental Restoration Program (ERP) documents, 
including those not kept at the Information Repositories, and the 
Docket for this proposed partial deletion are kept in the 
Administrative Record. The Administrative Record is available for 
public viewing at the Base Environmental Management Flight, 2103 Scott 
Drive, Ellsworth AFB, SD 57706. To schedule an appointment or for Base 
access call (605) 385-2680.

FOR FURTHER INFORMATION CONTACT: Mr. John Dalton, Community Involvement 
Coordinator (8OC), U.S. EPA, Region 8, 999 18th Street, Suite 300, 
Denver, CO 80202-2466, Phone: (303) 312-6633.

Table of Contents

I. Introduction
II. NPL Deletion Criteria
III. Deletion Procedures
IV. Basis for Intended Partial Site Deletion
V. Deletion Action

I. Introduction

    The EPA announces its intent to delete portions of the Ellsworth 
AFB Site (CERCLIS ID SD2571924644), from the NPL and requests 
comments on this proposed action. The NPL constitutes Appendix B to the 
NCP, 40 CFR part 300, which EPA promulgated pursuant to Section 105 of 
CERCLA as amended, 42 U.S.C. 9605. The NPL is a list of facilities 
which EPA determined may pose a significant threat to public health, 
welfare, or the environment. 40 CFR 300.425(e) authorizes deletion of 
facilities, or portions of facilities, from the NPL provided that 
facility meets certain criteria. Deletion from the NPL does not 
necessarily preclude further remedial action. If a significant release 
occurs at a facility deleted from the NPL, that facility is restored to 
the NPL without application of the Hazard Ranking System. Federal 
facilities are not eligible for Superfund-financed remedial action. 
However, all Federal facilities, whether listed on the NPL or not, have 
a continuing statutory duty to conduct further remediation, if 
required, even after the Federal property is transferred to non-Federal 
owners. When a release attributable to a Federal facility's historical 
activities is discovered after a property transfer, CERCLA section 
120(b)(3)(A)(i) requires the federal entity to conduct further 
remediation if necessary for the protection of human health and the 
environment.
    An environmental assessment was conducted at Ellsworth AFB on the 
parcels proposed for deletion. All media were sampled. Results of the 
sampling were reported in Remedial Investigation (RI) reports which 
were used to conduct Risk Assessments. Feasibility Studies (FS) were 
generated which evaluated potential remedies required to address the 
contamination. The remedies were summarized in a public notice 
soliciting comments on the remedies. All public comments received 
during the public comment periods were considered by the Air Force and 
EPA before the final remedy was selected.
    The parcels proposed for deletion are described in more detail 
later in this document. EPA proposes deleting these parcels from the 
NPL because no further CERCLA response is appropriate. The remaining 
portions of the property comprising the Ellsworth AFB Site will remain 
on the NPL. This notice will be published in the Federal Register to 
solicit public comments on the proposed partial deletion. The public 
comment period is thirty (30) days beginning on the date of 
publication.
    Section II of this action explains the criteria for the partial 
deletion of sites from the NPL. Section III discusses the procedures 
that EPA is using for this action. Section IV discusses the history of 
the Ellsworth AFB Site and explains how the portions of the Site 
proposed for deletion meet deletion criteria. Section V states EPA's 
intention to delete the portions of the Site from the NPL unless 
dissenting comments are received during the comment period.

II. NPL Deletion Criteria

    The NCP establishes the criteria that are used to delete sites from 
the NPL. In accordance with 40 CFR 300.425(e), sites may be deleted 
from the NPL where no further response is appropriate to protect human 
health or the environment. In making such a determination pursuant to 
40 CFR 300.425(e), EPA will consider, in consultation with the State, 
whether any of the following have been met:
    (1) Section 300.425(e)(1)(i). Responsible parties or other persons 
have implemented all appropriate response actions required; or
    (2) Section 300.425(e)(1)(ii). All appropriate Fund-financed 
response under CERCLA has been implemented, and no further response 
action by responsible parties is appropriate; or
    (3) Section 300.425(e)(1)(iii). The remedial investigation has 
shown that the release poses no significant threat to human health or 
the environment and, therefore, taking of remedial measures is not 
appropriate.
    As explained below, portions of the Ellsworth AFB Site meet the 
NCP's deletion criteria listed above. Therefore, partial deletion is 
being proposed.

III. Deletion Procedures

    Upon determination that at least one of the criteria described in 
40 CFR 300.425(e) of the NCP has been met, EPA may formally begin 
deletion procedures. The following procedures were used for the 
proposed partial deletion of portions of Ellsworth AFB:
    (1) All appropriate responses under CERCLA have been implemented 
and no further action is appropriate for the identified areas;
    (2) The State of South Dakota through the Department of Environment 
and Natural Resources concurred with this proposed partial deletion 
decision via a letter dated February 10, 2006;
    (3) Concurrent with this Notice of Intent for Partial Deletion, 
notice has been published in the Rapid City Journal (the newspaper of 
record) and has been distributed to appropriate Federal, State, and 
local officials, and other interested parties. These notices announce a 
thirty (30) day public comment period on the deletion package, which 
commences on the date of publication of this notice in the Federal 
Register and the Rapid City Journal; and
    (4) All relevant documents have been made available for public 
review at the local information repositories listed previously.
    Upon completion of the 30-day comment period, EPA will evaluate all 
comments received before issuing the final decision on partial 
deletion. If appropriate, EPA will prepare and issue a Responsiveness 
Summary for comments received during the public comment period and will 
address concerns presented in the comments. The Responsiveness Summary 
will be made available to the public at the information repositories. 
Members of the public are encouraged to contact EPA to obtain a copy of 
the Responsiveness Summary. If, after review of all public comments, 
EPA determines that the partial deletion from

[[Page 36738]]

the NPL is appropriate, EPA will publish a Final Notice of Partial 
Deletion in the Federal Register. As stated in 40 CFR 300.425, a site, 
or portion of a site, deleted from the NPL, remains eligible for future 
response actions if conditions warrant.

IV. Basis for Intended Partial Site Deletion

    The following site summary provides EPA's rationale for the 
proposed partial deletion. It also includes information demonstrating 
satisfaction of the deletion criteria specified under 40 CFR 
300.425(e).

Background

    Ellsworth AFB is a U.S. Air Force Air Combat Command (ACC) 
installation located 12 miles east of Rapid City, South Dakota, and 
adjacent to the small community of Box Elder. The main Air Base covers 
approximately 4,858 acres within Meade and Pennington counties and 
includes runways, airfield operations, industrial areas, housing, and 
recreational facilities. The site was officially activated in July 1942 
as the Rapid City Army Air Base, a training facility for B-17 bomber 
crews. Ellsworth AFB has been the headquarters of operations for a 
variety of aircraft, the Titan I Intercontinental Ballistic Missile 
system and the Minuteman I and Minuteman II Missile systems. The Base 
has historically provided support, fueling, training, maintenance, and/
or testing facilities. Operations at Ellsworth AFB over the years 
generated a variety of waste materials including municipal solid waste, 
wastewater treatment plant sludge, industrial wastes including waste 
oils, solvents, paints, spilled fuels, waste pesticides, shop waste, 
metal remains from ordnance disposal (shell casings and bomb fragments 
but not unexploded ordnance) and radiological wastes. Contaminants of 
concern at Ellsworth AFB include chlorinated solvents, waste fuels and 
metals.
    Ellsworth AFB is located within the following Sections, Townships, 
and Ranges, in Pennington and Meade Counties, South Dakota:
    Sections 35 and 36, Township 3 North, Range 8 East, Meade County;
    Section 31, Township 3 North, Range 9 East, Meade County;
    Sections 1, 2, 11, 12, 13, Township 2 North, Range 8 East, 
Pennington and Meade Counties; and
    Sections 5, 6, 7, 8, 17, 18, 19, Township 2 North, Range 9 East, 
Pennington and Meade Counties.
    Ellsworth AFB was placed on the NPL August 30, 1990 (55 FR 35509) 
and is therefore subject to the provisions of Section 120 of CERCLA, 42 
U.S.C. 9620. At that time the entire base, approximately 4,858 acres, 
was included in the listing (``fence line to fence line''). The 
Department of Defense, EPA and the State of South Dakota entered into a 
Federal Facilities Agreement (FFA) which formalizes the process for 
environmental response actions and the relative roles of the Air Force, 
the EPA and the State of South Dakota under CERCLA and the Installation 
Restoration Program (IRP). The FFA was signed by the Air Force, the 
EPA, and the State of South Dakota in January, 1992 and became 
effective on April 1, 1992.
    Upon listing, the facility began identifying sites where activities 
involving hazardous substances may have occurred. The sites requiring 
further investigations were grouped into Operable Units (OUs). Twelve 
OUs have been identified at Ellsworth AFB. The OUs include: OU-1, Fire 
Protection Training Area; OU-2, Landfills Nos. 1 and 6; OU-3, Landfill 
No. 2; OU-4, Landfill No. 3; OU-5, Landfill No. 4; OU-6, Landfill No. 
5; OU-7, Weapons Storage Area; OU-8, Explosive Ordnance Disposal Area; 
OU-9, Old Auto Hobby Shop Area; OU-10, North Hangar Complex; OU-11, 
Basewide Ground Water; and OU-12, Hardfill No. 1. Records of Decision 
(RODs) have been finalized for all of these OUs. Appropriate response 
actions for soil media have been completed per ROD decisions at the 10 
OUs proposed for deletion. The RI/FS process did not identify any 
unacceptable risks for surface water and sediment at these OUs. 
Therefore, remedial actions were not required for surface water and 
sediment. Remedial activities for areas where there has been a release 
or disposal of petroleum products have been deferred to action under 
the SDDENR petroleum release program.
    The portions of the Ellsworth AFB Site to be deleted from the NPL 
include surface soil, unsaturated subsurface soil, surface water and 
sediment media at OU-2, OU-3, OU-4, OU-5, OU-6, OU-7, OU-8, OU-9, OU-10 
and OU-12 (approximately 542 acres) and the surface soil, unsaturated 
subsurface soil, surface water and sediment media of an additional 
4,300 acres which are not associated with an operable unit and are not 
identified as posing a risk to human health or the environment.
    Of the approximately 4,858 acres originally included in the 
Ellsworth AFB site NPL listing in 1990, there are four areas that are 
not being deleted. These areas are:
     OU-1 (all media) [generally described by the following 
coordinates: N667749.88/E1242611.11; N667496.84/E1242812.29; 
N667330.75/E1242852.01; N666933.49/E1242558.40; N667158.53/E1242265.75; 
N667787.47/E1242276.80; N667749.88/E1242611.11]
     OU-11 (Basewide Ground Water) [including all ground water 
plumes located within the Base boundary (described earlier) and those 
described as emanating from the Base]
     Gateway Lake Ash Study Area [generally described by the 
following coordinates: N667944.01/E1248056.74; N667694.15/E1248058.87; 
N667695.57/E1247811.84; N667947.55/E1247834.49; N667944.01/E1248056.74]
     Pride Hanger Study Area [generally described by the 
following coordinates: N673538.32/E1243066.96; N673267.45 /E1243270.27; 
N673228.21/E1243223.95; N673113.04/E1243308.87; N673021.04/E1243204.65; 
N673409.00/E1242911.91; N673538.32/E1243066.96]
    Maps identifying all areas are available for review in the partial 
deletion docket.

Operable Unit 2

    The OU-2 study area consists of Landfill No. 1, Landfill No. 6, the 
drainage channel in the western portion of Landfill No. 1, and the 
drainage channel near Landfill No. 6, which includes Pond 002.
    Landfill No. 1 is approximately 21.5 acres in size and is located 
at the southern boundary of Ellsworth AFB. The landfill was active from 
the early 1940s to 1964 and was used to dispose of a variety of wastes 
including Base refuse, incinerator ash, sludge, oil, and possibly 
liquid industrial wastes. Hardfill debris was also disposed of at 
Landfill No. 1.
    Landfill No. 6 is approximately 0.5 acres in size and is located 
northeast of Landfill No. 1 on the north side of Kenney Road. Landfill 
No. 6 was used from 1962 to 1965 and primarily received general Base 
refuse. Waste oil, fuel, and solvents may also have been disposed of at 
this location. However, no direct physical evidence of these chemicals 
was found at Landfill No. 6 during the 1993/1994 remedial investigation 
field activities.
    Within OU-2, soils contained chlorinated volatile organic compounds 
(VOCs), benzene, toluene, ethyl benzene, xylenes (BTEX), pesticides, 
inorganic compounds, and polynuclear aromatic hydrocarbons (PAHs). The 
concentrations of several inorganic compounds exceed background 
concentrations. This is believed to be a combination of landfill 
activities and variations in the concentrations of

[[Page 36739]]

naturally-occurring compounds in the soil. Jet fuel contamination 
caused by a leak in a fuel line was identified along the southern 
boundary of OU-2. This jet fuel contamination has been remediated under 
the SDDENR petroleum release program. Sediment samples collected at OU-
2 contained semi-volatile organic compounds (SVOCs), primarily PAHs, 
pesticides and inorganic compounds. Low concentrations of three SVOCs 
were detected in surface water samples at OU-2, as well as numerous 
inorganic compounds. The concentrations of several inorganic compounds 
exceeded State and Federal water quality standards. However, the 
results of the risk assessment indicated that risk due to exposure to 
contaminants in sediments at OU-2 was within the acceptable risk range, 
and that surface water was not a media of current concern. Therefore, 
it was determined that remedial action was not warranted for surface 
water or sediment.
    Two removal actions were completed at this OU. A site in the 
southwest corner of Landfill 1 identified during RI geophysical 
investigations was excavated in 1997. This location contained low-level 
radioactive waste material. A second removal action was completed for 
remnants of chemical weapons training materials located in the same 
general area. The identified materials were excavated and moved off 
Site for disposal at a licensed waste disposal facility.
    The ROD was signed in May of 1996. The selected alternative for 
Landfill No. 1 was a vegetated soil cover and institutional controls. 
This alternative includes institutional controls, storm-water channel 
realignment and lining, in conjunction with physical modification of 
the OU to reduce potential risk. The selected alternative for Landfill 
No. 6 was institutional controls. This alternative uses access 
restriction, monitoring, and other controls to reduce potential risk. 
Construction for the storm-water channel was completed in October 1996. 
The landfill cover was completed in May 1997. Ground water remediation 
and monitoring are part of OU-11.

Operable Unit 3

    OU-3, located in the northeast portion of Ellsworth AFB, consists 
of Landfill 2, (approximately one acre), the four identified trenches 
to the north and two disturbed soil areas in the southeast and 
southwest corners. The landfill was active for approximately one year 
(1964-1965). Combustible trash, described as shop wastes, was burned 
daily in a burn pit. Four trenches located north of the fill area were 
used for the disposal of metal and industrial and household refuse. A 
sign located within the boundary of OU-3 indicates a missile disposal/
burial site. The missile disposal site contains scrap metal salvaged 
from a test flight. Contaminants identified in soil at this OU include, 
VOCs, jet fuel, numerous SVOCs, pesticides and inorganic compounds. The 
concentrations of several inorganic compounds exceed background 
concentrations.
    The ROD was signed in June of 1996. The selected remedial action 
was a vegetated soil cover. This alternative includes institutional 
controls in conjunction with physical modification of the OU to reduce 
potential risk. The landfill cover was completed in May 1997. Ground 
water monitoring is part of OU-11.

Operable Unit 4

    OU-4 (Landfill No. 3) is approximately 40 acres in size and is 
located in the southwestern corner of Ellsworth AFB. The landfill was 
active between 1965 and 1976 as a trench and fill operation. The 
landfill was also used for disposal of construction demolition debris 
during the mid-1980s, digested wastewater treatment plant biomass, shop 
wastes (liquids and paints), industrial sewer sludge and oils, soil 
containing Pramitol and sodium chromate, and miscellaneous refuse. The 
contents of approximately 100 55-gallon drums containing waste oil and 
fuel were placed in a waste-oil pit on site. OU-4 was also used as a 
staging area for 55-gallon drums containing waste oil and fuel. In 
addition, the southwest corner of OU-4 was used to stage asphalt 
rubble. Contaminants in soil at the OU include VOCs, PAHs, jet fuel, 
pesticides, polychlorinated biphenyls (PCBs), inorganic compounds, 
dioxins and furans. The concentrations of several inorganic compounds 
exceed background concentrations. Contaminants in sediment include 
acetone, PAHs, pesticides, and inorganic compounds. However, it was 
determined in the risk assessment that those levels of contaminants 
fell within the acceptable risk range and therefore, no remedial action 
was warranted for sediment.
    The ROD was signed in May of 1996. The selected remedial action was 
a vegetated soil cover for the landfill, and extraction and treatment 
for ground water. This alternative includes institutional controls in 
conjunction with physical modification of the OU to reduce potential 
risk. The landfill cover was completed in December 1996. Ground water 
remediation and monitoring are part of OU-11.

Operable Unit 5

    OU-5 (Landfill No. 4) is a 10-acre site located adjacent to the 
north perimeter of Ellsworth AFB. From the 1940s through 1990, the 
landfill was used primarily for the disposal of construction demolition 
and hardfill materials, general refuse and drums. Contaminants in soil 
at OU-5 include PAHs, pesticides, inorganic compounds, and jet fuel. 
The concentrations of several inorganic compounds exceed background 
concentrations. One surface water and one sediment sample were 
collected at OU-5 from an ephemeral surface water source. These samples 
contained VOCs, SVOCs, and inorganic compounds. However, it was 
determined in the risk assessment that those levels of contaminants 
fell within the acceptable risk range and therefore, no remedial action 
was warranted for surface water or sediment.
    The ROD was signed in June of 1996. The selected remedial action 
was a vegetated soil cover. This alternative includes institutional 
controls in conjunction with physical modification of the OU to reduce 
potential risk. The landfill cover was completed in May 1997. Ground 
water monitoring is part of OU-11.

Operable Unit 6

    OU-6 (Landfill No. 5) is a 7-acre site located in the southeastern 
corner of Ellsworth AFB. From 1960 to 1980, demolition debris and 
hardfill materials were placed in the landfill along with miscellaneous 
refuse, dried sewage sludge, and possibly shop wastes. Construction and 
demolition debris was initially placed along the rail line to stabilize 
erosion, and was later expanded to the east. OU-6 was used for 
stockpiling wastewater treatment plant sludge. Contaminants in soil at 
OU-6 include PAHs, pesticides, and inorganic compounds. The 
concentrations of several inorganic compounds exceed background 
concentrations. Contaminants in surface water and sediment include 
VOCs, SVOCs, pesticides and inorganic compounds. However, it was 
determined in the risk assessment that those levels of contaminants 
fell within the acceptable risk range and therefore, no remedial action 
was warranted for surface water or sediment.
    The ROD was signed in October of 1995. The selected remedial action 
was a vegetated soil cover, and long-term surface water and sediment 
sampling. This alternative includes institutional controls in 
conjunction with physical modification of the OU to reduce potential 
risk. The landfill cover was

[[Page 36740]]

completed in July 1996. Ground water monitoring is part of OU-11.

Operable Unit 7

    OU-7 (Low-Level Radioactive Waste Burial Site) is located in the 
Munitions Storage Area (MSA), formerly identified as the Weapons 
Storage Area (WSA), at the northernmost end of Ellsworth AFB. The MSA 
covers approximately 65 acres. Radioactive wastes were generated at 
Ellsworth AFB between 1952 and 1962. During that time the WSA was under 
the control of the Atomic Energy Commission (AEC). After 1962, control 
of the WSA was transferred to the Air Force. Contaminants in soil at 
OU-7 include VOCs and inorganic compounds. Contaminants in surface 
water and sediment include VOCs and inorganic compounds. The 
concentrations of several inorganic compounds in soil and sediment 
exceed background concentrations. Radionuclides detected in all media 
were within the normal background range due to natural variations in 
soil types and geological characteristics. The results of the risk 
assessment indicated that risk due to exposure to contaminants in 
surface water and sediments at OU-7 was within the acceptable risk 
range. Therefore, it was determined that remedial action was not 
warranted for surface water or sediment.
    The ROD was signed in June of 1996. The selected remedial action 
was application of institutional controls for soil and ground water, 
completion of detailed records searches and long term ground water 
monitoring. Ground water monitoring is part of OU-11.

Operable Unit 8

    OU-8 (Explosive Ordnance Disposal Area) is located in the 
northeastern portion of Ellsworth AFB. OU-8 consists of two distinct 
areas, the Explosive Ordnance Disposal (EOD) Area and the Debris Burial 
Area. The EOD Area is approximately 600 feet by 1,350 feet, and the 
Debris Burial Area is approximately 300 feet by 150 feet. The EOD Area 
includes: A Pramitol (an herbicide) spill area, a burn pit area, a burn 
furnace area, and a detonation site. This detonation area was formerly 
used for the detonation of active explosives. The Debris Burial Area 
was used for the burial of debris generated from detonation of 
explosives at the demolition area. Contamination in soil at this OU 
includes VOCs, SVOCs (primarily PAHs), jet fuel, pesticides, dioxins/
furans, and inorganic compounds. The concentrations of several 
inorganic compounds in soil and sediment exceed background 
concentrations. One pesticide was detected in sediment samples. 
However, it was determined in the risk assessment that those levels of 
contaminants fell within the acceptable risk range and therefore, no 
remedial action was warranted for sediment.
    The ROD was signed in June of 1996. The selected remedial action 
was installation of vegetated soil covers, application of institutional 
controls and long term sediment sampling. The soil covers over the EOD 
Area and the Debris Burial Area were completed in June 1997. Ground 
water monitoring is part of OU-11.

Operable Unit 9

    OU-9 encompasses 90 acres surrounding the Old Auto Hobby Shop. The 
types of potential contaminant source areas at OU-9 include: Building 
Operations, underground storage tanks, the former Quartermaster 
Gasoline Dispensing Area, the former fuel transfer line, industrial 
waste lines, jet engine test facilities and upgradient source areas. 
There is no known documentation of major spills or releases at OU-9. 
Small volumes of fuels, oils, and solvents may have been released to 
the environment over time through incidental spills, leaks, and/or poor 
waste handling and disposal practices. Contaminants in soil at this OU 
include VOCs (primarily BTEX), SVOCs (primarily PAHs), jet fuel, and 
inorganic compounds. Several inorganic compounds were detected in 
surface water and sediment samples. PAHs were also reported in sediment 
samples.
    It was determined that OU-9 did not pose a threat to human health 
or the environment. In May 1996, a ROD was signed for no further 
action. Remediation of soils contaminated by petroleum will be 
performed under the SDDENR petroleum release program. Ground water 
remediation was deferred to OU-11.

Operable Unit 10

    OU-10 is the North Hangar Complex, a 75-acre site located in the 
central portion of Ellsworth AFB, northeast of the primary instrument 
runway. The North Hangar complex was constructed in the 1950s and is 
composed of five rows of aircraft repair and maintenance hangars. Most 
of OU-10 is paved with concrete with some grassy areas between the 
hanger rows. OU-10 contains a system of underground jet fuel hydrant 
lines that deliver fuel to docked aircraft, and underground industrial 
waste lines associated with aircraft maintenance. It was reported that 
waste products used for aircraft maintenance may have been washed down 
floor drains in the maintenance buildings. Contaminants at this OU 
included VOCs, SVOCs and jet fuel. The predominant VOCs were BTEX 
compounds.
    It was determined that OU-10 did not pose a threat to human health 
or the environment. In May 1996, a ROD was signed for no further 
action. Remediation of soils contaminated by petroleum will be 
performed under the SDDENR petroleum release program. Ground water 
remediation was deferred to OU-11.

Operable Unit 12

    OU-12 (Hardfill No. 1) is located in the southern half of Ellsworth 
AFB and is approximately 14 acres in size. OU-12 was identified as a 
hardfill, rather than a landfill, because disposal records indicated 
that it only received construction debris such as wood, metal, 
concrete, and asphalt. The remedial investigation identified the 
presence of VOCs, SVOCs, jet fuel and pesticides, but through site 
characterization it was found that these contaminants were related to 
flightline runoff rather than landfill disposal practices.
    The ROD was signed in May of 1996. The selected remedial action was 
a vegetated soil cover. This alternative includes institutional 
controls in conjunction with physical modification of the OU to reduce 
potential risk. The soil cover was completed in May 1997. Ground water 
monitoring is part of OU-11.

Five-Year Review

    The initial five-year review for Ellsworth AFB base was completed 
in September 2000. The second five-year review was completed in 
September 2005. The reviews focused on the final remedial activities at 
each OU. Discussions and recommendations were included for the long-
term ground water actions at the OUs and for Operation and Maintenance 
issues with landfill covers.

V. Deletion Action

    EPA, with the State of South Dakota's concurrence, has determined 
that no additional response is necessary at Ellsworth AFB for surface 
soil, unsaturated subsurface soil, surface water and sediment media at 
OU-2, OU-3, OU-4, OU-5, OU-6, OU-7, OU-8, OU-9, OU-10 and OU-12 
(approximately 542 acres) and the surface soil, unsaturated subsurface 
soil, surface water and sediment media of an additional 4,300 acres 
which are not associated with an operable unit and are

[[Page 36741]]

not identified as posing a risk to human health or the environment.
    No further CERCLA response is appropriate or necessary to provide 
protection of human health and the environment other than the ongoing 
inspection, maintenance and monitoring activities. Therefore EPA is 
deleting these portions of the Ellsworth AFB Site. OU-1, OU-11, the 
Pride Hanger Study Area and the Gateway Lake Ash Study Area will remain 
on the NPL.

    Dated: June 8, 2006.
Kerrigan G. Clough,
Acting Regional Administrator, U.S. Environmental Protection Agency, 
Region 8.
 [FR Doc. E6-10105 Filed 6-27-06; 8:45 am]

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