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[Federal Register Volume 77, Number 49 (Tuesday, March 13, 2012)]
[Proposed Rules]
[Pages 14717-14723]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-6031]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 300

[EPA-HQ-SFUND-1990-0011; FRL-9646-1]

National Oil and Hazardous Substances Pollution Contingency Plan; 
National Priorities List: Partial Deletion of the Ellsworth Air Force 
Base Superfund Site

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule; notice of intent.

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SUMMARY: The Environmental Protection Agency (EPA) Region 8 is issuing 
a Notice of Intent to Delete Operable Unit (OU) 1 the former Fire 
Protection Training Area (FPTA), along with two other Areas of Concern 
(AOC): The Gateway Lake Ash Study Area and the Pride Hangar Study Area 
of the Ellsworth Air Force Base (AFB) Superfund Site located in Meade 
and Pennington Counties, South Dakota, from the National Priorities 
List (NPL) and requests public comments on this proposed action. The 
NPL, promulgated pursuant to section 105 of the Comprehensive 
Environmental Response, Compensation, and Liability Act (CERCLA) of 
1980, as amended, is an appendix of the National Oil and Hazardous 
Substances Pollution Contingency Plan (NCP). The EPA and the State of 
South Dakota, through the Department of Environment and Natural 
Resources, have determined that all appropriate response actions at 
these identified parcels under CERCLA other than five year reviews have 
been completed. However, this deletion does not preclude future actions 
under Superfund.
    This partial deletion pertains to the surface soil, unsaturated 
subsurface soil, surface water and sediments of Operable Unit (OU) 1, 
the Gateway Lake Ash Study Area, and the Pride Hangar Study Area. The 
groundwater medium associated with OU-11, Basewide Groundwater, will 
remain on the NPL and is not being considered for deletion as part of 
this action. The other OUs associated with Ellsworth AFB were deleted 
in 2006.

DATES: Comments must be received by April 12, 2012.

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 on-line instructions 
for submitting comments.
     Email: dalton.john@epamail.epa.gov.
     Fax: 303-312-6961.
     Mail: Mr. John Dalton, Community Involvement Coordinator 
(8OC), U.S. EPA, Region 8, 1595 Wynkoop St., Denver, CO 80202.
     Hand delivery: 1595 Wynkoop St., Denver, CO 80202. Such 
deliveries are only accepted during the Docket's normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information.
    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 email. 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 email comment directly to EPA without 
going through http://www.regulations.gov, your email 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

[[Page 14718]]

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 information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in the hard 
copy. Publicly available docket materials are available either 
electronically in http://www.regulations.gov or in hard copy at:
    U.S. EPA Records Center, Region 8, 1595 Wynkoop Street, Denver, CO 
80202-1129, (303) 312-6312, Hours: Mon-Fri, 8:30 a.m. to 5 p.m.
    South Dakota Air & Space Museum, 2890 Davis Drive, Building 5208, 
Ellsworth AFB, SD 57706, (605) 385-5188, Hours: Mon-Fri, 7 a.m. to 4 
p.m.

FOR FURTHER INFORMATION CONTACT: Mark Aguilar, Remedial Project 
Manager, U.S. Environmental Protection Agency, Region 8, 1595 Wynkoop 
Street, Denver, CO 80202-1195, (303) 312-6251, email: 
aguilar.mark@epamail.epa.gov.

SUPPLEMENTARY INFORMATION: 

Table of Contents

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

I. Introduction

    EPA Region 8 announces its intent to delete OU-1, the Gateway Lake 
Ash Study Area, and the Pride Hangar Study Area of the Ellsworth AFB 
Superfund Site, from the National Priorities List (NPL) and requests 
public comment on this proposed action. 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) of 1980, as amended. EPA maintains the NPL 
as the list of sites that appear to present a significant risk to 
public health, welfare, or the environment. Sites on the NPL may be the 
subject of remedial actions financed by the Hazardous Substance 
Superfund (Fund). This partial deletion of the Ellsworth AFB Site is 
proposed in accordance with 40 CFR 300.425(e) and is consistent with 
the Notice of Policy Change: Partial Deletion of Sites Listed on the 
National Priorities List, 60 FR 55466 (Nov. 1, 1995). As described in 
300.425(e)(3) of the NCP, a portion of a site deleted from the NPL 
remains eligible for Fund-financed remedial action if future conditions 
warrant such actions.
    EPA will accept comments on the proposal to partially delete this 
site for thirty (30) days after publication of this document in the 
Federal Register.
    Section II of this document explains the criteria for deleting 
sites from the NPL. Section III discusses procedures that EPA is using 
for this action. Section IV discusses OU-1, the Gateway Lake Ash Study 
Area, and the Pride Hangar Study Area of the Ellsworth AFB Superfund 
Site and demonstrates how they meet the deletion criteria.

II. NPL Deletion Criteria

    The NCP establishes the criteria that EPA uses 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. 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 criteria have 
been met:
    i. Responsible parties or other persons have implemented all 
appropriate response actions required;
    ii. All appropriate Fund-financed response under CERCLA has been 
implemented, and no further response action by responsible parties is 
appropriate; or
    iii. The remedial investigation has shown that the release poses no 
significant threat to public health or the environment and, therefore, 
the taking of remedial measures is not appropriate.
    Pursuant to CERCLA section 121(c) and the NCP, EPA conducts five-
year reviews to ensure the continued protectiveness of remedial actions 
where hazardous substances, pollutants, or contaminants remain at a 
site above levels that allow for unlimited use and unrestricted 
exposure. EPA conducts such five-year reviews even if a site is deleted 
from the NPL. EPA may initiate further action to ensure continued 
protectiveness at a deleted site if new information becomes available 
that indicates it is appropriate. Whenever there is a significant 
release from a site deleted from the NPL, the deleted site may be 
restored to the NPL without application of the hazard ranking system.

III. Deletion Procedures

    The following procedures apply to deletion of OU-1, the Gateway 
Lake Ash Study Area, and the Pride Hangar Study Area of the Site:
    (1) EPA consulted with the State before developing this Notice of 
Intent for Partial Deletion.
    (2) EPA has provided the state 30 working days for review of this 
notice prior to publication of it today.
    (3) In accordance with the criteria discussed above, EPA has 
determined that no further response is appropriate.
    (4) The State of South Dakota, through the Department of 
Environment and Natural Resources, has concurred with the deletion of 
OU-1, the Gateway Lake Ash Study Area, and the Pride Hangar Study Area 
of the Ellsworth AFB Superfund Site, from the NPL.
    (5) Concurrently, with the publication of this Notice of Intent for 
Partial Deletion in the Federal Register, a notice is being published 
in a major local newspaper, the Rapid City Journal. The newspaper 
announces the 30-day public comment period concerning the Notice of 
Intent for Partial Deletion of the Site from the NPL.
    (6) The EPA placed copies of documents supporting the proposed 
partial deletion in the deletion docket and made these items available 
for public inspection and copying at the Site information repositories 
identified above.
    If comments are received within the 30-day comment period on this 
document, EPA will evaluate and respond accordingly to the comments 
before making a final decision to delete OU-1, the Gateway Lake Ash 
Study Area, and the Pride Hangar Study Area. If necessary, EPA will 
prepare a Responsiveness Summary to address any significant public 
comments received. After the public comment period, if EPA determines 
it is still appropriate to delete OU-1, the Gateway Lake Ash Study 
Area, and the Pride Hangar Study Area of the Ellsworth AFB Superfund 
Site, the Regional Administrator will publish a final Notice of Partial 
Deletion in the Federal Register. Public notices, public submissions 
and copies of the Responsiveness Summary, if prepared, will be made 
available to interested parties and included in the site information 
repositories listed above.
    Deletion of a portion of a site from the NPL does not itself 
create, alter, or revoke any individual's rights or obligations. 
Deletion of a portion of a site from the NPL does not in any way alter 
EPA's right to take enforcement actions, as appropriate. The NPL is

[[Page 14719]]

designed primarily for informational purposes and to assist EPA 
management. Section 300.425(e)(3) of the NCP states that the deletion 
of a site from the NPL does not preclude eligibility for future 
response actions, should future conditions warrant such actions.

IV. Basis for Partial Site Deletion

    The following information provides EPA's rationale for deleting OU-
1, the Gateway Lake Ash Study Area, and the Pride Hangar Study Area of 
the Ellsworth AFB Superfund Site from the NPL.

Site Background and History

    The Ellsworth AFB Superfund Site (CERCLIS ID 
SD2571924644), is a United States Air Force Air Combat Command 
installation located 12 miles east of Rapid City, South Dakota, and 
adjacent to the small community of Box Elder. 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.
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. Ellsworth AFB 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 was proposed for listing on the NPL October 26, 1989 
(54 FR 43779), 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, 
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 were 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 Hobby Shop Area; OU-10, North Hangar Complex; OU-11, Basewide 
Groundwater; and OU-12, Hardfill No. 1. Records of Decision (RODs) were 
finalized for all of these OUs between October 1995 and April 1997.
    Surface soil, unsaturated subsurface soil, surface water, and 
sediments 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 not associated with an operable unit were deleted from the 
NPL December 4, 2006 (71 FR 70318).
    Four areas not deleted in 2006 were OU-1 (all media), OU-11 
(Basewide Groundwater) [including all groundwater plumes located within 
the Base boundary and those described as emanating from the Base], and 
two Areas of Concern: the Gateway Lake Ash Study Area and the Pride 
Hangar Study Area. Appropriate response actions for soil media have 
since been completed at OU-1, the Pride Hangar Study Area and the 
Gateway Lake Ash Study Area. The remedial investigation/feasibility 
study (RI/FS) process did not identify any unacceptable risks for 
surface water and sediment at these areas. Therefore, remedial actions 
were not required for surface water and sediment.
    The portions of the Ellsworth AFB Site to be deleted from the NPL 
are:
     Surface soil, unsaturated subsurface soil, surface water 
and sediment media at OU-1 [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]
     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 Hangar 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].
    OU-1 consists of the former Fire Protection Training Area (FPTA), 
Pond 001, and a portion of the drainage channel that leads into Pond 
001. The former FPTA is approximately 10 acres in size and is located 
in the southwestern portion of Ellsworth AFB. The FPTA was operated by 
the Ellsworth AFB at this location from 1942 to 1990. The location of 
the burn area within the former FPTA has changed several times over the 
years. Aerial photographs of Ellsworth AFB show numerous areas of 
staining presumed to be a result of the fire training activities within 
the former FPTA. The training exercises conducted at the FPTA involved 
simulation of aircraft fires and spills and consisted of dispersing 
various fuels, oils and solvents within the burn pit area and 
subsequently igniting and extinguishing the fire. Extinguishing 
chemicals used during the fire-training exercises have included 
aqueous-film-forming-foam, halon, protein-foams, carbon dioxide, dry 
chemicals and chlorobromomethane.
    The Gateway Lake Ash Study Area is located in the southeast portion 
of Ellsworth AFB. The site is located in a low area approximately 400 
feet south of Gateway Lake and north of the Ellsworth AFB wastewater 
treatment facility. The area is generally level open terrain that is 
grass covered and bounded on the north by trees and on the east by an 
unnamed creek. To the west is the entrance road to the Base's 
wastewater treatment plant and to the south is the wastewater plant.
    The open land that contains the Gateway Lake Ash Study Area had 
come

[[Page 14720]]

under consideration for construction of a new building when soils at 
the proposed building site were assessed. Two exploratory geotechnical 
borings were drilled in August 2002 that encountered ash debris and 
glass material. Further evaluation provided information that the area 
was once an open ravine which had been filled with ash and debris. An 
incinerator to the south was identified as a potential source of the 
fill debris. Over time, the area had been graded and a portion within 
the fenced boundary of the wastewater treatment facility had been 
seeded with grass. Except for the planted trees to the north, the 
remaining area has since grown over with natural grass and shrubs.
    The Pride Hangar Study Area is located at the northwest corner of 
the Pride Hangar within OU-11 and covers approximately 1.7 acres. Two 
former side-by-side waste solvent underground storage tanks located on 
the northwest corner of the Pride Hangar were the primary source of a 
TCE plume known as the Pride Hangar plume. These tanks were removed in 
1992.
    A map identifying the areas to be deleted is available in the 
partial deletion docket. The groundwater medium at the Ellsworth AFB 
Site (OU-11, Basewide Groundwater) will remain on the NPL and response 
activities will continue for that OU.

Operable Unit 1

    An extensive RI was conducted to characterize site conditions at 
OU-1 in 1993 and 1994. The program included completion of boreholes, 
installation of monitoring wells, geotechnical analysis of soil 
samples, ecological investigations, assessment of human health risks, 
and review and compilation of previous IRP investigations. Collection 
and laboratory analysis of soil, groundwater, surface water, and 
sediment samples were included in the RI field program.
    Soil impacted by past activities at OU-1 extends from the surface 
to the capillary fringe beneath the former FPTA. The nature of the soil 
contamination at OU-1 soils included JP-4 (jet fuel), benzene, toluene, 
ethylbenzene and xylene (BTEX), and chlorinated volatile organic 
compounds (VOCs). JP-4 contamination was in a range of hundreds of 
thousands to millions of micrograms per kilogram ([micro]g/kg) in 
vadose zone and capillary fringe soils. Total BTEX contamination was in 
a range of non-detect (ND) to hundreds of thousands of [micro]g/kg in 
vadose zone soils, and thousands to tens of thousands of [micro]g/kg in 
capillary fringe soils. Total chlorinated VOCs contamination was in a 
range of ND to tens of [micro]g/kg in vadose zone soils, and ND to 
hundreds of [micro]g/kg in capillary fringe soils.
    A baseline risk assessment indicated that the soils of the burn-pit 
area posed an unacceptable risk, primarily from the potential for 
contaminating the underlying groundwater. Risks from exposure to 
pesticides and dioxins/furans in surface and subsurface soils at OU-1 
were well below the acceptable range and did not warrant remediation. 
Contaminants in surface water and sediment included VOCs, semi-volatile 
organic compounds (SVOC), pesticides, one phthalate, one polynuclear 
aromatic hydrocarbon and inorganics including cyanide, thallium, 
mercury, arsenic, manganese and nickel. However, it was determined in 
the risk assessment that the levels of these contaminants fell within 
the acceptable risk range, and therefore, no remedial action was 
warranted for surface water or sediment.
    A Final ROD for an Interim Remedial Action (IRA) for OU-1 was 
signed in May 1995. The objective of the IRA at OU-1 is to reduce the 
immediate risks posed by the contaminants in the deeper subsurface 
soils of the burn-pit areas of the FPTA and to prevent the movement of 
contaminants to shallow ground-water. The interim remedy included soil 
vapor extraction (SVE), groundwater removal using wells and an existing 
interceptor trench, treatment of groundwater, condensate, and soil gas, 
and surface water discharge of treatment effluent. Only the SVE system 
pertains the media being proposed for deletion. The SVE system 
consisted of four dual phase extraction wells and eight soil vapor 
extraction wells, and a soil vapor blower with soil gas treated by 
thermal oxidation before discharge.
    The OU-1 SVE system began operation in March 1996 and operated 
until the final remedy was implemented. The thermal oxidizer was 
operated from March 1996 to November 1996 when blower discharge 
contaminant levels were low enough to discharge to the atmosphere.
    The 1995 Feasibility Study for OU-1 recommended expanding the IRA 
SVE system to remove volatile organic chemicals from source area soils. 
A Final ROD for Remedial Action at OU-1 was signed in May 1996. The 
remedial action objectives (RAOs) are: (1) The cleanup of ground water 
to regulatory levels and, for contaminants where regulatory levels are 
not available, to levels considered safe for public drinking water, and 
(2) the cleanup of source area soils to levels that would not pose a 
threat of contaminating ground water. The selected remedial action 
included: continued operation of the IRA SVE system to remediate a 
portion of the source area soils; use of groundwater wells and an 
existing collection trench to remove contaminated groundwater in the 
source area; installation and use of additional SVE wells, groundwater 
wells and/or collection trenches; treatment of soil gas and 
contaminated groundwater at the IRA treatment plant; implementing 
institutional controls (deed and land use restrictions) to restrict the 
future use of the area while the remedy is being implemented; and 
providing for long-term monitoring and maintenance. Only the SVE system 
and the institutional controls apply to the media being proposed for 
deletion.
    The Final ROD set cleanup goals for four VOCs identified for 
remediation in soil: benzene (10 [micro]g/kg), 1,2-dichloroethylene 
(DCE) (41 [micro]g/kg), tetrachloroethylene (PCE) (10 [micro]g/kg), and 
trichloroethylene (TCE) (10 [micro]g/kg). Cleanup goals for these four 
VOCs were based on model estimates for the protection of groundwater. 
Where model estimates were less than standard detection limits, 
remediation cleanup goals were based on standard detection limits. 
Remediation of jet fuel in the soil at OU-1 was also required because 
concentrations of jet fuel and related components exceeded State of 
South Dakota regulations. Cleanup goals for petroleum related 
contamination were set at: JP-4 (500,000 [micro]g/kg), toluene (15,000 
[micro]g/kg), ethylbenzene (10,000 [micro]g/kg), xylene (300,000 
[micro]g/kg), and naphthalene (25,000 [micro]g/kg).
    An additional SVE blower, seven dual phase extraction wells, a dual 
phase extraction trench and four soil vapor extraction wells were 
installed as part of the Final Remedial Action. The IRA system was 
incorporated into the final remedy. Construction of the remedial action 
was completed in June 1997.
    This alternative included institutional controls, implemented 
August 27, 1997, to prevent human exposure to contaminated soil and 
groundwater. These controls include: (1) Issuing a continuing order to 
restrict on-site worker access to contaminated soil, and to restrict or 
control temporary construction activities unless proper protective 
equipment is worn; (2) filing a notice with the State to recommend 
denial of water appropriation permit applications to install 
groundwater wells within the area of contamination and any area which 
may be effected by potential contaminants; (3) filing a notice to the 
deed detailing the restrictions of the continuing order and groundwater 
well restrictions; and (4) a covenant to the deed in the event of

[[Page 14721]]

property transfer. The continuing order is reissued with 5-year reviews 
and the most recent is dated August 5, 2010.
    Operation and maintenance of the SVE system included collecting 
samples at the blower stacks and calculating mass removals, 
measurements of individual well vacuums and contaminant levels, and 
blower vacuum. Based on these measurements, operation of the SVE wells 
and the SVE component of dual phase wells were optimized by applying 
vacuum to the points of highest contaminant concentration. Based on 
system monitoring, one SVE blower was shut off in March 2000 and 
operation of one SVE blower was focused on wells with the highest 
contaminant concentration. Two additional dual phase extraction wells 
were installed in June 2003 and began operation in October 2003 to 
address free product and improve groundwater plume containment.
    SVE operation continued until July 2007. SVE operation was 
suspended in 2007 because monitoring data showed that SVE contaminant 
mass removal rates had diminished significantly and the removal rates 
remained low.
    A high vacuum extraction system (HVE) was operated from May to 
November 2007 and from May to November 2008. The HVE system operated at 
15 wells (nine monitoring wells and six dual extraction wells) with the 
primary purpose of removing residual free product. Operation and 
maintenance of the HVE system included measuring hydrocarbon 
concentrations in the vapor discharge, measurement of vacuum at 
individual wells and at the vacuum blower, and drawdown at individual 
wells. Operation of the HVE system was suspended in November 2008 after 
free product was no longer observed at any of the wells on site.
    A bioventing system was operated at OU-1 from November 2008 through 
August 2010 to enhance the biological degradation of fuel-related 
contaminants BTEX; naphthalene; and total petroleum hydrocarbons as 
gasoline-range organics [GRO] and diesel-range organic [DRO]) in the 
vadose zone soils. Bioventing was designed to replace the SVE system 
and utilized existing SVE wells, dual extraction wells, and associated 
piping. Fifteen SVE and dual extraction wells were used in the 
bioventing system. Operation and maintenance of the bioventing system 
included measuring oxygen and carbon dioxide levels in bioventing 
wells, and recording pressure, temperature and flow from the blower.
    Post one year bioventing soil samples were collected in January 
2010 at six boring locations where soil samples collected in 1989 or 
1993 had exceeded OU-1 soil cleanup goals. Analytical results from 
vadose zone soils for ethylbenzene, naphthalene, toluene and xylene at 
the six borings were all below reporting limits (6.9 [micro]g/kg 
maximum) and below cleanup goals based on State Regulations for each 
compound (ethylbenzene 10,000 [micro]g/kg, naphthalene 25,000 [micro]g/
kg, toluene 15,000 [micro]g/kg, and xylene 300,000 [micro]g/kg). The 
maximum DRO result from the vadose zone soil samples was 210,000 
[micro]g/kg and the maximum GRO result from the vadose zone soil 
samples was 1,700 [micro]g/kg, both below the cleanup goal of 500,000 
[micro]g/kg for JP-4 in soil based on State Regulation.
    With respect to the contaminants of concern cis-1,2-DCE, benzene, 
PCE, and TCE, the analytical results in the vadose zone showed the 
concentrations were all below reporting limits, which were below the 
cleanup goals established in the Final ROD. These data demonstrate the 
cleanup goals have been met.
    The 2010 5-year review recommend evaluating existing data to 
determine if partial deletion of surface soil, unsaturated subsurface 
soil, surface water and sediment from OU-1 is appropriate. Subsequent 
data evaluation indicated that unsaturated soils met the cleanup levels 
documented in the ROD and is protective of groundwater. The next five 
year review is scheduled for the year 2015.

Gateway Lake Ash Study Area

    Electromagnetic survey data from the August 2003 Draft Preliminary 
Assessment/Site Investigation (PA/SI) Report indicated the areal extent 
of the ash and debris was approximately \1/3\ acre. Field observations 
and soil borings indicated the ash and debris were 6 to 7.5 feet in 
thickness and typically encountered within one foot of the surface.
    The PA/SI reported contaminants in the ash and debris and soils 
including VOCs, SVOCs, metals and dioxins/furans. Detected results were 
compared to the USEPA Region 3 Risk Based Concentrations (RBCs). The 
industrial soil screening value at a 1x 10-6 risk level was used for 
dermal and inhalation risk and the dilution attenuation factor (DAF) of 
20 was used for evaluating the soil to groundwater migration pathway. 
Detected metal concentrations were compared to regional concentration 
ranges as established in the RI Report for nearby OU-6.
    Three VOCs were detected in the ash and debris but concentrations 
did not exceed industrial or DAF 20 values. Five SVOCs (1,4-
dichlorobenzene, 2,4-dintrotoluene, 4-nitrophenol, N-nitrosodi-N-
propylamine, and 1,2,4-trichlorbenzene) exceeded DAF 20 standards and 
one SVOC (N-nitrosodi-N-propylamine) exceeded industrial soil standards 
in the ash and debris. Four VOCs and one SVOC were detected in the soil 
beneath the ash and debris but concentrations did not exceed industrial 
or DAF 20 screening levels. Low concentrations of VOCs and SVOCs in the 
underlying soils indicated the contaminants in the buried ash and 
debris did not greatly impact the underlying soils.
    Metals were detected in the ash and debris with arsenic exceeding 
RBCs but within the range of background concentration in surrounding 
soils. Arsenic and mercury exceeded both industrial and DAF 20 
screening levels. Manganese exceeded the DAF 20 screening level in the 
underlying soil but was considered to be within background ranges. 
Toxicity Characteristic Leaching Potential metals and pH analysis 
indicated the ash and debris material was non-hazardous. Results for 
dioxins/furans indicated the maximum concentration in the ash and 
debris was below screening criteria and similar to background 
concentrations. Based on the characterization of the ash and debris and 
no evidence of contaminant migration under the debris or outside the 
buried debris limits, no further actions were recommended. No RI or FS 
was completed for the Gateway Lake Ash Study Area soils.
    The Air Force, independent of CERCLA, determined that the ash 
material should be removed from the site and disposed properly at a 
licensed land disposal facility (the Rapid City Landfill). In January 
2007, 4,310 cubic yards of ash material was hauled to the Rapid City 
Landfill and used as daily cover material. Confirmation sampling of 
underlying soils for SVOCs detected one SVOC compound, bis(2-
ethylhexyl)phthalate, at 74 [micro]g/kg, that was below the DAF 20 
value of 2,889,000 [micro]g/kg for that compound. The excavated area 
was restored by backfilling with clean soil from stockpiles and 
excavations on Base, and reseeding the site. The characterization of 
the ash and debris, removal of the ash debris from the site, and 
results from confirmation sampling in the underlying soil demonstrate 
that the site is clean.
    The Gateway Lake Ash Study Area overlies OU-11, Basewide 
Groundwater. As a result, the institutional controls for OU11 apply to 
this area. The ICs selected in the 1997 OU11 ROD included (1) issuing a 
continuing order

[[Page 14722]]

(by the Installation Commander) to restrict or place limitations on the 
installation of any new groundwater wells; (2) filing a notice in 
environmental and real estate records at the Base or Installation, 
detailing the restrictions of the continuing order and groundwater well 
restrictions; and (3) compliance with the provisions of CERCLA Section 
120(h)(3) or other applicable statutory requirements in the event of 
property transfer. These ICs were implemented August 27, 1997.
    The Gateway Lake Ash Study Area was addressed in the 2010 Five Year 
Review as an area not deleted during the previous partial deletion. No 
recommendations were made regarding the Gateway Lake Ash Study Area in 
the 2010 Five Year Review. The next five year review is scheduled for 
the year 2015.

Pride Hangar Study Area

    The Pride Hangar Study Area is located at the northwest corner of 
the Pride Hangar within OU-11 Area 1 and covers approximately 1.7 
acres. Two former side-by-side waste solvent underground storage tanks 
located on the northwest corner of the Pride Hangar were the primary 
source of a TCE plume known as the Pride Hangar plume. These tanks were 
removed in 1992. A soil sample was collected from near the floor of the 
tank excavation (10 feet below ground surface) in1993 and analyzed for 
VOC. TCE was reported at 0.09 mg/kg.
    During the 1994 RI for OU-11 Basewide Groundwater, a groundwater 
sample collected near the tank site contained total 1,2-DCE at 11 
[micro]g/L, chloroform at 1,580 [micro]g/L, TCE at 6,800 [micro]g/L and 
JP-4 at 270 [micro]g/L. A soil boring at that same location was non-
detect for VOCs and SVOCs in the capillary fringe. The FS for OU-11 
Basewide Groundwater Area 1 recommended, and the OU-11 ROD specified 
groundwater extraction and treatment in OU-11 Area 1. A vacuum 
extraction system was installed to extract contaminated groundwater and 
operated southeast (downgradient) of the Pride Hangar from 1997 to 
2006. No RI or FS was completed for soils at the Pride Hangar Study 
Area.
    Additional soil sampling was completed at the Pride Hangar Study 
Area in 2002. In eleven vadose zone soil samples, TCE results ranged 
from kg to 120 [micro]g/kg and cis-1,2-DCE was detected in 
only one sample at 40 [micro]g/kg. The September 3, 2003 Serial Letter 
1-54-RA-301, Pride Hangar Source Remediation Recommendation, 
recommended SVE to remove chlorinated VOCs in the vadose zone at the 
Pride Hangar Study Area. This action was implemented and consisted of 
SVE pilot testing in May 2004 and intermittent operation of the SVE 
system from July to November 2004. The SVE system consisted of an SVE 
blower, eight SVE wells, and temporary above-ground piping. Operation 
and maintenance of the SVE system included monitoring vacuum at the 
wells and blower, and vapor flow rate at the blower. The SVE system was 
shut down due to the potential aeration of groundwater and its 
detrimental effect on anaerobic groundwater treatment implemented in 
2004. A 2007 Explanation of Significant Differences allowed for 
continued use of the SVE system at the Pride Hangar Study Area even but 
the SVE system was not operated again.
    Vadose zone soil samples were collected from direct push borings in 
the Pride Hangar Study Area in 2010. Soil samples included samples 
collected in the vadose zone at the depths where chlorinated VOC 
concentrations were highest in 2002. TCE concentrations in vadose zone 
samples were all non-detect except for three detections at 
concentrations of 0.58, 0.52 and 0.52 [micro]g/kg. These TCE 
contaminant concentrations are above the most conservative EPA Regional 
Screening Level for protection of groundwater for TCE but are within 
the acceptable risk range given the change in the TCE toxicity value. 
Cis-1,2-DCE concentrations in vadose zone samples were all non-detect 
except for one detection of 0.81 [micro]g/kg. This cis-1,2-DCE 
concentration is below the EPA Regional Screening Level for protection 
of groundwater for cis-1,2-DCE of 21 [micro]g/kg for a DAF of one. 
These vadose zone soil sample results, reported in the August 2011 
Pride Hangar Vadose Zone Soil Sample Results technical memorandum, 
indicated a significant source of contaminated soil no longer existed.
    The Pride Hangar Study Area overlies OU-11, Basewide Groundwater. 
As a result, the institutional controls for OU11 apply to this area. 
The ICs selected in the 1997 OU11 ROD included (1) issuing a continuing 
order (by the Installation Commander) to restrict or place limitations 
on the installation of any new groundwater wells; (2) filing a notice 
in environmental and real estate records at the Base or Installation, 
detailing the restrictions of the continuing order and groundwater well 
restrictions; and (3) compliance with the provisions of CERCLA Section 
120(h)(3) or other applicable statutory requirements in the event of 
property transfer. These ICs were implemented 27 August 1997.
    The Pride Hangar Study Area was addressed in the 2010 Five Year 
Review as an area not deleted during the previous partial deletion. No 
recommendations were made regarding the Pride Hangar Study Area in the 
2010 Five Year Review. The next five year review is scheduled for the 
year 2015.

Community Involvement

    Community involvement activities that have taken place include 
publishing the FFA and RODs for public comment, establishing and 
maintaining an Administrative Record, and formation of a Restoration 
Advisory Board (RAB) to facilitate input in the cleanup process. The 
RAB includes Ellsworth AFB, EPA and SDDENR oversight personnel as well 
as community leaders and local representatives from the surrounding 
area. RAB meetings are held twice each year, normally in May and 
November.

Determination That the Criteria for Deletion Have Been Met

    EPA, with concurrence from the State of South Dakota, through the 
Department of the Environment and Natural Resources, by a letter dated 
November 22, 2011, has determined that no additional response is 
necessary at Ellsworth AFB for surface soil, unsaturated subsurface 
soil, and surface water and sediment media at OU-1, the Gateway Lake 
Ash Study Area and the Pride Hangar Study Area. Responsible parties 
have completed all appropriate response actions required and the 
unsaturated subsurface soil is cleaned up at OU-1 and the Pride Hangar 
Study Area. Investigation of the Gateway Lake Ash Study Area showed 
that it posed no significant threat to public health or the environment 
and removal of the debris eliminated any potential threat, therefore, 
the taking of remedial measures is not appropriate. Therefore, EPA is 
proposing to delete these portions of the Ellsworth AFB Site.
    EPA Region 8 has followed the procedures required by 40 CFR 
300.425(e). The EPA has consulted with the State of South Dakota and 
provided the state 30 working days for review of this notice prior to 
publication. The State, through the Department of Environment and 
Natural Resources has concurred with the deletion of surface soil, 
unsaturated subsurface soil, and surface water and sediment media at 
OU-1, the Gateway Lake Ash Study Area and the Pride Hangar Study Area 
from the Ellsworth AFB Superfund Site. Concurrent with the publication 
of the Notice of Intent for Partial Deletion in

[[Page 14723]]

the Federal Register, a notice is being published in The Rapid City 
Journal. The EPA placed copies of documents supporting the proposed 
partial deletion in the deletion docket, and made these items available 
for public inspection and copying at the Site information repositories.

List of Subjects in 40 CFR Part 300

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

    Authority:  33 U.S.C. 1321(c)(2); 42 U.S.C. 9601-9657; E.O. 
12777, 56 FR 54757, 3 CFR, 1991 Comp., p. 351; E.O. 12580, 52 FR 
2923, 3 CFR, 1987 Comp., p. 193.

    Dated: February 8, 2012.
James B. Martin,
Regional Administrator, Region 8.
[FR Doc. 2012-6031 Filed 3-12-12; 8:45 am]
BILLING CODE 6560-50-P
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