### 14717 Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Proposed Rules

NAEMS began in the summer of 2007 and consisted of 24 monitoring sites located in nine states. In addition, Tyson Foods, Inc. collected data from two broiler sites, which are also
included in the NAEMS dataset.
Academic researchers from various
universities conducted the NAEMS study with EPA oversight. At the animal confinement sites, the study was designed to collect process and emissions data for ammonia (NH 3 ), hydrogen sulfide (H 2 S), total suspended particulate matter (TSP), particulate matter with aerodynamic diameters less than 10 micrometers (PM 10 ), PM with aerodynamic diameters less than 2.5 micrometers (PM 2.5 ), and volatile organic compounds (VOCs). For lagoons and basins, the study was designed to
collect NH 3 , H 2 S and VOCs.

In accordance with the Agreement’s monitoring protocol, the EPA developed draft EEMs for animal housing structures and manure storage and treatment units using the emissions and process data collected under the
NAEMS and other relevant information. Once the draft EEMs are final, the EPA expects that the AFO industry will use the EEMs to estimate daily and annual emissions for use in determining AFOs’ regulatory responsibilities under the Clean Air Act, the Comprehensive Environmental Response, Compensation and Liability Act, and the EmergencyPlanning and Community Right-toKnow Act.

The draft documents describe the sites monitored, the statistical methodology used to analyze the data,
and the EEMs.

The agency is requesting comment on the draft documents with particular emphasis on the statistical methodology used to develop the emissions estimating methodologies. Please submit comments within 90 days of the date of this notice. Electronic copies of the
documents are available at www.epa.gov/airquality/agmonitoring

.

On February 17, 2012, EPA’s Office of Air Quality Planning and Standards sent
a memorandum to the EPA Science Advisory Board Staff Office titled, ‘‘Animal Feeding Operations Air Emissions Estimating Methodologies
from the National Air Emissions Monitoring Study’’ asking the Science Advisory Board to review and provide
comments on these documents.

In response to EPA’s memorandum, the EPA’s Science Advisory Board has formed an expert panel to review and provide comments on these documents. The Science Advisory Board review process is an independent process. Information on submitting comments to the Science Advisory Board can be found at www.epa.gov/sab . Additional information about the Science Advisory Board process can be found at: http:// yosemite.epa.gov/sab/sabproduct.nsf/0/
ae6639dd6b79360e852579a4004e5529 !OpenDocument. The Science Advisory Board anticipates multiple meetings of the expert panel to cover the documents
in this notice.

The EPA will consider public comments received in response to this notice, public comments submitted to the Science Advisory Board, and the Science Advisory Board panel
recommendations as the final emissions estimating methodologies are developed.

Dated: February 29, 2012.
Janet McCabe, Acting Assistant Administrator.

[FR Doc. 2012–5550 Filed 3–12–12; 8:45 am]

**BILLING CODE 6560–50–P**

**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.

**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


### 14718 Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Proposed Rules

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


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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


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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 ( m 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 mg/kg in vadose zone soils, and thousands to tens
of thousands of m g/kg in capillary fringe
soils. Total chlorinated VOCs contamination was in a range of ND to
tens of mg/kg in vadose zone soils, and
ND to hundreds of mg/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 movementof contaminants to shallow groundwater. 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 beingimplemented; and providing for longterm 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 mg/kg), 1,2- dichloroethylene (DCE) (41 mg/kg), tetrachloroethylene (PCE) (10 mg/kg), and trichloroethylene (TCE) (10 mg/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 mg/kg), toluene (15,000 m g/kg), ethylbenzene (10,000 mg/ kg), xylene (300,000 mg/kg), and naphthalene (25,000 m 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


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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 mg/kg maximum) and below cleanup goals based on State Regulations for each compound (ethylbenzene 10,000 m g/kg, naphthalene 25,000 m g/kg, toluene

15,000 mg/kg, and xylene 300,000 m g/ kg). The maximum DRO result from the vadose zone soil samples was 210,000

m g/kg and the maximum GRO result from the vadose zone soil samples was

1,700 m g/kg, both below the cleanup goal of 500,000 mg/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, Nnitrosodi-N-propylamine, and 1,2,4- trichlorbenzene) exceeded DAF 20standards and one SVOC (N-nitrosodiN-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 mg/kg, that
was below the DAF 20 value of

2,889,000 mg/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


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(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 m g/L, chloroform at 1,580 m g/L, TCE at 6,800

m g/L and JP–4 at 270 m 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 <5 mg/ kg to 120 m g/kg and cis-1,2–DCE was detected in only one sample at 40 m 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 invadose zone samples were all nondetect except for three detections at concentrations of 0.58, 0.52 and 0.52 m 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 m 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 mg/ 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


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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]

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