[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 <5 [micro]g/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