PB95-964417
EPA/ROD/R08-95/115
March 1996
EPA Superfund
Record of Decision:
Hill Air Force Base,
Operable Unit 7, UT
9/28//1995
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TABLE OF CONTENTS
PAGE
DECLARATION FOR THE RECORD OF DECISION
DECISION SUMMARY FOR THE RECORD OF DECISION
1.0 SITE NAME, LOCATION, AND DESCRIPTION 1-1 -
2.0 SITE HISTORY AND ENFORCEMENT ACnvmES 2-1
2.1 Site History 2-1
2.2 Investigation History 2-2
2.3 Enforcement Activities 2-4
2.4 Community Relations History 2-5
2.5 Scope and Role of Operable Unit 7 Within Site Strategy 2-5
3.0 SUMMARY OF SITE CHARACTERISTICS 3-1
3.1 Nature and Extent of Contamination 3-1
3.2 Summary of Fate and Transport of Contaminants 3-3
4.0 PUBLIC HEALTH AND ENVIRONMENTAL IMPACTS 4-1
4.1 Human Health 4-1
4.1.1. Contaminant Identification 4-1
4.1.2. Exposure Assessment 4-1
4.1.3. Toxicity Assessment 4-4
4.1.4. Risk Characterization 4-4
4.1.5. Uncertainties 4-7
4.2 Threats to the Environment 4-9
4.2.1. Surface Water, Ground Water, and Wetlands 4-9
4.2.2. Vegetation 4-9
4.2.3. Wildlife 4-9
4.2.4. Air Quality 4-9
4.2.5. Archaeological Resources 4-10
4.3 Summary of Site Risks 4-10
5.0 DESCRIPTION OF ALTERNATIVES 5-1
5.1 Development of Alternatives . 5-1
5.2 Detailed Analysis of Alternatives 5-3
5.3 Comparative Analysis of Alternatives ' 5-8
5.3.1. Evaluation Criteria 5-8
5.3.2. Comparative Analysis 5-9
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Table of Contents
6.0 SELECTED REMEDY 6-1
6.1 Description of the Selected Remedy 6-1
6.1.1. Remediation Goals and Performance Standards 6-2
6.1.2. Restoration Time Frame 6-3
6.1.3. Costs 6-3
6.2 Statutory Determinations 6-4
6.2.1. Protection of Human Health and the Environment 64
6.2.2. Compliance with Applicable or Relevant and Appropriate 6-4
Requirements
6.2.3. Cost Effectiveness 6-7
6.2.4. Utilization of Permanent Solutions 6-7
6.2.5. Preference for Permanent Solutions and Treatment 6-8
Technologies that are Practical
6.3 Documentation of Significant Changes 6-8
RESPONSIVENESS SUMMARY
REFERENCES R-l
APPENDIX A -ARARs PERTAINING TO ACTIVITIES AT OU 7
APPENDIX B -PUBLIC MEETING TRANSCRIPT
APPENDIX C -WRITTEN COMMENTS AND RESPONSES
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Table of Contents
LIST OF TABLES
TABLE
NO. TITLE PAGE
2-1 Summary of Previous Environmental Investigations at OU 7 2-3
3-1 Chemicals Detected in OU 7 Source Areas 3-2
4-1 Hill OU 7 Chemicals of Concern for Soil 4-2
4-2 Summary of Slope Factors for Potential Contaminants of Concern 4-5
4-3 Reference Doses 4-6
4-4 Summary of Cancer Risks and Hazard Indices by Pathway: Future Exposures 4-8
5-1 Preliminary Remedial Goals for Soil at OU 7 5-2
5^2 Development of Remedial Alternatives for OU 7 Soil 5-4
5-3 Summary of Key ARARs for Each Alternative 5-11
6-1 Summary of Key ARARs for the Selected Remedy 6-6
A-l Identification of Federal Chemical-Specific ARARs
A-2 Identification of State Chemical-Specific ARARs
A-3 Identification of Federal Act ion-Specific ARARs
A-4 Identification of State Action-Specific ARARs
LIST OF FIGURES
FIGURE FOLLOWING
NO. TITLE PAGE NO.
1-1 Location of Operable Units 1-1
1-2 Buildings 225 and 220 Facilities Map 1-1
1-3 Base Supply Well 6 Location map 1-1
3-1 Isoconcentration Map for Hexavalent Chromium in Soil 3-2
3-2 Isoconcentration Map for Cadmium in Soil 3-2
3-3 Geologic Cross Section of Former Metal Plating Shop Area Showing 3-2
Vertical Distribution of Hexavalent Chromium Contamination
3-4 Generalized Conceptual Model of Contaminant Transport 3-3
3-5 Conceptual Model of Past Contaminant Transport 3-3
6-1 Conceptual Remedial Action Implementation Schedule 6-2
111
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Hill Air Force Base, Utah
Operable Unit 7
Declaration for the Record of Decision
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Site Name and Location
Operable Unit 7
Hill Air Force Base, Utah
Weber and Davis Counties, Utah
Statement of Basis and Purpose
This decision document presents the selected remedy for Hill Air Force Base (Hill AFB)
Operable Unit 7 (OU 7) in Davis County, Utah. Sites addressed in this document include
the former Metal Plating Shop in Building 225, the PCB Spill Area in Building 225,
Miscellaneous Areas in Building 225, Base Supply Well 6, and Building 220. The
selected remedy was chosen in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA) and, to the extent practicable,
with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
This decision is based on the Administrative Record for Hill AFB.
The State of Utah, the U.S. Environmental Protection Agency (EPA), and Hill AFB
concur on the selected remedy.
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may
present an imminent and substantial endangerment to public health, welfare, or the
environment.
Current risks to human health associated with the contaminants at OU 7 are well below
levels considered by the EPA to be significant. Remedial action for contaminated soils
beneath the former Metal Plating Shop is warranted based on possible future risks to
human health and the environment, and because of future threats to the ground water
beneath OU 7. Based on the findings of the OU 7 Remedial Investigation and Risk
Assessment, Building 220, Base Supply Well 6, the PCB Spill Area and Miscellaneous
Areas in Building 225 do not require remedial actions because risks posed by the
contaminants at these sites are below significant levels.
Description of the Selected Remedy
OU 7 is one of nine operable units at Hill AFB. OU 7 is a soils-only OU and consists of
soil contamination at several source areas in and around Buildings 220 and 225, and some
imported fill (from Building 225) at Base Supply Well 6. The two buildings lie in the
south central portion of the Base, west of the main runway in an industrial area that has
been used to service aircraft since the 1940s. Base Supply Well 6 is located northwest of
the north end of the main runway. Subsurface conditions are dominated by interbedded
silty sands, sandy silts, and clays. Ground water beneath OU 7 is addressed separately in
Operable Unit 8. Therefore, references to contaminated ground water in this document
are only mentioned and further discussion is outside the scope of this ROD. The
remaining operable units are at various stages in the remedial investigation/feasibility
study (RI/FS) process. The selected remedy at OU 7 addresses the threat to human health
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and the environment posed by soils contamination associated with the former Metal
Plating Shop in Building 225, through institutional controls. These controls will maintain
existing structures over the contamination source area, restrict future access to the area
where contaminated soil is present, and monitor the potential for future contaminant
movement.
The major components of the selected remedy for Hill AFB OU 7 include:
Ground-water quality monitoring in areas upgradient, beneath, and
downgradient of the area where contaminant concentrations in soils are above
health-based risk levels.
Soil moisture content monitoring around the perimeter of and within the area
of contaminated soils.
Maintaining and preserving the building and floor slab that overlay the
contaminated soils.
Issuance of a continuing order from the Base commander that will restrict
worker access to the contaminated soils as long as Hill AFB owns the
property.
A notice to the deed will be filed by the Air Force detailing the restrictions of
the continuing order.
A covenant in the deed which incorporates the restrictions of the continuing
order and, upon transfer of the property, establishes the locations and
restrictions of use of the contaminated area, and retains rights of access for
future response actions, if needed. If land use is changed or Building 225 is
removed, the Air Force will reevaluate the protectiveness of the selected
remedy and perform any necessary remedial actions.
Posting warning signs regarding the presence of contaminated soils that could
represent a threat to human health.
Statutory Determinations
The selected remedy is protective of human health and the environment, complies with
Federal and State requirements that are legally applicable or relevant and appropriate to
the remedial action, and is cost-effective. This remedy utilizes permanent solutions and
alternative treatment (or resource recovery) technologies, to the maximum extent
practicable for this site. However, because treatment of the principal threats of the site
was not found to be practicable, this remedy does not satisfy the statutory preference for
treatment as a principal element. Because this remedy will result in hazardous substances
remaining on-site that are above health-based levels, a review will be conducted within
five years after commencement of the remedial action to ensure that the remedy continues
to provide adequate protection of human health and the environment.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Robert L. Duprey,
Director, Hazardous Wagfe^Mana^ement Division
Date
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STATE OF UTAH DEPARTMENT OF ENVIRONMENTAL QUALITY
Dianne R. Nielson, Ph.D., Date
Executive Director
Record of Decision for
Hill Air Force Base Operable Unit 7
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HILL AIR FORCE BASE, UTAH
OPERABLE UNIT 7
DECLARATION FOR THE RECORD OF DECISION
LAWRENCE P. FARRELL, JR.
Lieutenant General, USAF
Vice Commander
11 OCT 1995
Date
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Hill Air Force Base, Utah
Operable Unit 7
Decision Summary for the
Record of Decision
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1.0 SITE NAME, LOCATION, AND DESCRIPTION
Hill Air Force Base, Utah (Hill AFB) is located in northern Utah, about 25 miles north of
Salt Lake City and about five miles south of Ogden, Utah in Weber and Davis counties
(Figure 1-1). Hill AFB covers about 6,700 acres on the Weber River Delta, a terrace that
lies about 300 feet above the surrounding valleys. The delta surface has slight to
moderate relief with elevations varying from approximately 4,600 feet above National
Geodetic Vertical Datum (NGVD) along the western boundary of Hill AFB to
approximately 5,045 feet above NGVD along the eastern boundary. In contrast, the
Wasatch Mountains, about four miles to the east, rise abruptly from the valley floor to an
elevation of over 9,000 feet above NGVD. The Great Salt Lake, approximately 12 miles
to the west, is presently at an elevation of approximately 4,201 feet above NGVD.
Most of the southern part of Hill AFB is occupied by industrial facilities, equipment
storage areas, and administration buildings related to the aircraft maintenance mission of
the Base. By contrast, the northern part of Hill AFB has large open areas with groups of
buildings that were constructed as munition manufacturing plants, assembly plants, or
storage facilities. Although the use of the old plants and storage facilities has changed in
recent years to missile storage, maintenance, and testing, the buildings and facilities
remain. Off-Base land use includes residential, commercial, and agricultural. This area
has undergone rapid residential development over the last 10 to 20 years, and agricultural
use has declined. Crop production in the agricultural areas primarily is the cereal grains
wheat and barley, and alfalfa. There is some pasture land, and in some areas livestock are
raised. In July 1987, the Base was placed on the Comprehensive Environmental
Response, Compensation and Liability Act (CERCLA), National Priorities List (NPL)
because of several sites where hazardous liquid and solid wastes generated by installation
operations were disposed.
Operable Unit 7 (OU 7) is a soils-only OU and consists of soil contamination at several
source areas in and around Buildings 220 and 225, and some imported fill (from Building
225) at Base Supply Well 6. The two buildings lie in the south central portion of the
Base, west of the main runway in an industrial area that has been used to service aircraft
since the 1940s (Figure 1-2). Base Supply Well 6 is located northwest of the north end of
the main runway (Figure 1-3). Subsurface conditions in these areas are dominated by
interbedded silty sand, sandy silt, and clay. Ground water beneath OU 7 is addressed
separately in Operable Unit 8.
The OU 7 area overlies three aquifers, although these aquifers are not included as part of
OU 7. The shallow aquifer consists of approximately 200 feet of relatively low-yielding
materials and lies at about 110 to 140 feet below the ground surface at OU 7. This
shallow aquifer is designated as Class II - Drinking Water Quality based on the State of
Utah classification criteria and the quality of ground water taken from uncontaminated
wells. The deeper Sunset and Delta aquifers are approximately 300 and 600 feet below
OU 7, respectively. They are used by Hill AFB and surrounding communities as
domestic water supplies. The Sunset and Delta Aquifers are classified as Class I -
Irreplaceable Source of Drinking Water or Class IIA - Current Source of Drinking Water
(USGS, 1992). According to the Hill AFB Comprehensive Plan (USAF, 1989), there are
no wetlands located on-Base in OU 7.
1-1
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o
Scale in Miles
f\ OPERABLE
PERABLE UNIT 4
OPERABLE UNIT 4
OPERABLE UNIT 5
OPERABLE UNIT 4
OPERABLE UNIT 7
(Base Supply Well
SOUTH
WEBER
HILL AIR FORCE BASE
OPERABLE UNIT
(Soil beneath
Bldgs 220 and 225)
OPERABLE UNIT 9
(Rest of the base)
OPERABLE UNIT 5
OPERABLE UNIT 1
OPERABLE UNIT 3
MAP AREA I 2000 Nonh
OPERABLE UNIT 8
Source: Current Hill AFB Documentation.
HILL AIR FORCE BASE
OPERABLE UNIT 7
LOCATION OF OPERABLE UNITS
FIGURE 1-1
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PROJECT NO. 2208.0875
0 100 200-
Scale in Feet
100
214
Former
wash rack
Hydraulic room
location
Mop cleaning
room location
Former metal
plating shop
location v
X
225
PCB spill I
location
Former ~
degreaser pit
location
Concrete separator
tanks (removed)
20,000 gal
gasoline tank
(removed)
.LT
EXPLANATION
Industrial waste pipeline
(post-1986 segments)
Industrial waste pipeline
~ (pre-1986 segments)
Shaded areas represent potential
source areas in this investigation.
Unpaved area
Approximate alignment
of industrial sewer line
HILL AIR FORCE BASE
OPERABLE UNIT 7
BUILDINGS 225 AND 220
FACILITIES MAP
FIGURE 1-2
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Trench where backfill soils from
Building 225 were deposited
(5 feet wide by 5 feet deep)
Source: Modified from ENH Mapping Inc.,
1983; Hill CE records.
fc
LU
HILL AIR FORCE BASE
OPERABLE UNIT 7
BASE SUPPLY WELL 6
LOCATION MAP
FIGURE 1-3
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2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.1 SITE HISTORY
Hill AFB has been the site of military activities since 1920, when the western portion of
what is now the Base was activated as the Ogden Arsenal, an Army Reserve depot. In
1940 and 1941, four runways were built and the Ogden Air Depot was activated. During
World War n, the Ogden Arsenal manufactured ammunition and was a distribution center
for motorized equipment, artillery, and general ordnance. The Ogden Air Depot's
primary operation was aircraft rehabilitation. In 1948, the Ogden Air Depot was renamed
Hill AFB, and in 1955, the Ogden Arsenal was transferred from the U.S. Army to the
U.S. Air Force. Since 1955, Hill AFB has been a major center for missile assembly and
aircraft maintenance. Currently, Hill AFB is part of the Air Force Materiel Command.
On-Base industrial processes associated with aircraft, missile, vehicle, and railroad
engine maintenance and repair include metal plating, degreasing, paint stripping, and
painting. These processes use numerous chemicals including chlorinated and non-
chlorinated solvents and degreasers, petroleum hydrocarbons, acids, bases, and metals.
In the past, chemicals and waste products were disposed of at the Industrial Waste
Treatment Plant (IWTP), in chemical disposal pits and landfills, and off-Base. Disposal
in chemical pits and landfills was discontinued by 1980. All wastes currently are treated
at the IWTP, recycled on-Base, or sent to off-Base treatment or disposal facilities.
Operable Unit 7 addresses contaminated soils beneath Buildings 225 and 220, and at a
site where soils originating from Building 225 were used as backfill in a water line trench
at Base Supply Well 6. The areas that compose OU 7 are depicted in Figures 1-2 and 1-3
and described briefly below.
Building 225 Former Metal Plating Shop. A metal plating shop was formerly located
along the east side of Building 225, as shown on Figure 1-2. The plating shop operated
from the 1940s until it was removed from Building 225 in 1972. Contents of the plating
solution tanks containing acids, bases, metal salts, and other chemicals frequently were
discharged into a floor drain system that was connected to the industrial waste pipeline.
Over time, the plating solutions corroded the drains and piping until leakage occurred.
Soil contamination was first identified beneath the former Metal Plating Shop area when
a utility trench was installed there in 1989. Samples revealed that soil beneath the area
was contaminated with several metals and low concentrations (less than 0.1 mg/kg) of
volatile organic compounds (VOCs). The principal metals of concern were hexavalent
chromium, total chromium, and cadmium.
Building 225 PCB Spill Area. Polychlorinated biphenyls (PCBs) were found in soil
beneath Building 225 approximately 100 feet west of the former Metal Plating Shop
(Figure 1-2). During excavation of a utility trench in 1989, unusual odors and discolored
soil were reported. A subsequent investigation revealed that the soil contained PCBs.
This area was the site of a former transformer storage area that was removed in the 1960s.
As part of a cleanup effort, 95 tons of contaminated soil were removed and disposed of at
a facility permitted by the Toxic Substances Control Act. Following the soil removal,
additional soil samples revealed that only insignificant concentrations (less than 0.23
mg/kg) of residual PCBs remained in localized areas.
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Miscellaneous Areas in Building 225. Soil beneath four other areas inside Building 225
was investigated during the Remedial Investigation at OU 7. These areas include: the
former Wash Rack and Degreaser Pit, the Hydraulic Room, and the Mop Cleaning Room.
At each of these areas, only low concentrations of several VOCs and metals were
detected.
Base Supply Well 6. This water well is one of several production wells that supply
water to Hill AFB. The well lies just west of the north end of the main runway
(Figures 1-1 and 1-3). Some soil excavated in the vicinity of the former Metal Plating
Shop in Building 225 was placed as fill along the discharge pipeline from Base Supply
Well 6. Analytical results of subsequent soil samples from the fill indicated low
concentrations of metals and cyanide.
Building 220. Building 220 is located east of Building 225 and adjacent to the main
runway (Figure 1-2). This building was constructed in 1957 and has been used as an
aircraft painting and paint stripping facility. Painting and paint stripping activities have
used many types of paints, paint strippers, solvents, acids, and other chemicals. Before
1986, three underground concrete separator tanks were located on the northwest side of
the building. These tanks were used to separate paint chips and sludge from the
wastewater solutions generated during paint stripping operations. Wastewater from the
tanks in turn was discharged to the industrial wastewater pipeline and the IWTP. In
1986, Building 220 was renovated and an addition was constructed over the area where
the separator tanks had been located. As part of the construction, the separator tanks and
attached piping system were redesigned and replaced. Sampling around the separator
tanks indicated that the soil beneath the tanks was contaminated with low concentrations
of VOCs, semi-volatile organic compounds (SVOCs), and metals. Some of the
contaminated soil was removed and taken to an off-Base hazardous waste disposal
facility before the building addition was constructed, and additional soil sampling results
indicated that only low concentrations of organic chemicals and metals are present in the
vicinity of the former separator tanks, pipeline locations, and around the perimeter of
Building 220.
2.2 INVESTIGATION HISTORY
As shown in Table 2-1, several environmental investigations of the OU 7 sites have been
performed. An initial environmental investigation at Building 220 characterized the
industrial wastewater generated by the paint stripping and painting activities (Radian,
1984). When the industrial wastewater system was suspected of being a potential source
of environmental contamination, soil and ground-water sampling around the perimeter of
Building 220 was conducted under the Installation Restoration Program (IRP; Radian,
1988). Additional soil sampling was conducted in 1986 at the north end of the building
when the three underground oil/water separator tanks were removed during an expansion
of the building (Hill AFB, 1987). The results of these investigations identified VOCs,
BNAEs, and metals contamination in the wastewater, and several VOCs and metals in the
soils beneath the north end of Building 220 where the Oil/Water Separator Tanks had
been located.
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TABLE 2-1
SUMMARY OF PREVIOUS ENVIRONMENTAL
INVESTIGATIONS AT OPERABLE UNIT 7
Date of
Document
Investigation
May 1988
November 1989
December 1991
February 1993
February 1995
Installation Restoration Program Phase II-Confirmation/Quantification
Stage I Building 220, Paint Hangar
Hill AFB PCB Spill Sampling and Cleanup in Building 225
Site Characterization Report for a Portion of Building 225 and Site
Investigation of Fill at Base Supply Well 6
Remedial Investigation/Feasibility Study Planning Documents: Work
Plan, Sampling and Analysis Plan, and Health and Safety Plan
Remedial Investigation/Feasibility Study Report for Operable Unit 7
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Environmental investigations in Building 225 focused initially on the utility trench
excavations that identified metals and PCB contamination in the soils beneath the hangar
floor. Following removal of PCB-contaminated soils, confirmation soil samples were
collected from the walls of the excavation. Analysis of the samples indicated that only
insignificant concentrations (less than 0.23 mg/kg) of residual PCBs remained around the
excavation following the removal action (Hill AFB, 1989).
To evaluate the nature and extent of metals contamination beneath the former Metal
Plating Shop and in fill talcen to Base Supply Well 6, a site characterization soil sampling
program was conducted (JMM, 1991). At the former Metal Plating Shop, 20 shallow soil
borings were drilled and soil samples were collected. At Base Supply Well 6, soil
samples were collected from backfill in the pipeline trench. The results of this program
indicated that elevated levels of total chromium, hexavalent chromium, and cadmium
were present beneath the former Metal Plating Shop. During the 1991 investigation, the
soil placed as backfill at Base Supply Well 6 was determined not to be a characteristic
hazardous waste through leachability testing.
A Remedial Investigation/Feasibility Study (RI/FS) of OU 7 began in the latter part of
1992 and continued until early 1995 (Montgomery Watson, 1995). The Remedial
Investigation (RI) confirmed the presence of contaminants inside of Building 220, at Base
Supply Well 6, in Building 225, at the PCB spill area, and in the former Metal Plating
Shop area. In addition, four other possible source areas were investigated inside of
Building 225, including the Mop Cleaning Room, a former TCE Degreaser Pit, the
former Wash Rack, and the Hydraulic Room. As part of the RI/FS, an assessment of
risks to human health and the environment from chemicals at OU 7 was conducted. The
results of this evaluation are presented in the baseline risk assessment (BRA) that is
included as Section 6.0 in the RI/FS for OU 7. The results of the RI, BRA, and FS are
summarized in Sections 3.0, 4.0, and 5.0 of this ROD respectively. Section 6.0 contains
details about the selected remedial alternative. In the Feasibility Study (FS) for OU 7,
remedial technologies with potential applications at OU 7 were assembled into five
alternatives. Each alternative then was evaluated according to requirements of the
National Oil and Hazardous Substances Contingency Plan (NCP). Following the RI/FS,
a preferred alternative for remediation of OU 7 was identified by the Air Force, EPA, and
the State of Utah in the Proposed Plan for OU 7, (Montgomery Watson, 1995a). The plan
was distributed to members of the community for review, comment, and to evaluate their
acceptance.
2.3 ENFORCEMENT ACTIVITIES
In July 1987, Hill AFB was placed on the CERCLA National Priorities List (NPL) by the
EPA. In 1991, Hill AFB entered into a Federal Facilities Agreement (FFA) between the
U.S. Air Force (USAF), the State of Utah Department of Health (now the Utah
Department of Environmental Quality [UDEQ]) and the U.S. Environmental Protection
Agency (EPA). The purpose of the agreement was to establish a procedural framework
and schedule for developing, implementing, and monitoring appropriate response actions
2-4
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at Hill AFB in accordance with existing regulations. Seven operable units initially were
defined under the FFA. Two more operable units have since been added. This Record of
Decision (ROD) concludes all of the remedial investigation/feasibility study requirements
for OU 7. There have been no removal actions, remedial actions, Notices of Violation, or
other enforcement actions taken at OU 7 prior to this ROD.
2.4 COMMUNITY RELATIONS HISTORY
The public participation requirements of CERCLA Section 113(k)(2)(B)(i-v) and
Section 117 were met. Hill AFB has a Community Relations Plan that was finalized in
February 1992. The community relations activities include: (1) a Remedial Advisory
Board (RAB) which meets at least quarterly and includes community representatives
from adjacent counties and towns, (2) a mailing list for interested parties in the
community, (3) a bimonthly newsletter called "EnviroNews," (4) visits to nearby schools
to discuss environmental issues, (5) community involvement in a noise abatement
program, (6) semi-annual town council meetings, (7) opportunities for public comment
on remedial actions, (8) community interviews, and (9) support for the community for
obtaining technical assistance grants (TAGs).
The RI/FS Report for Operable Unit 7 (Montgomery Watson, 1995) and the Proposed
Plan for Operable Unit 7 (Montgomery Watson, 1995a) were released to the public, and
are available in the Administrative Record maintained in the Davis County Library and at
the Environmental Management Directorate at Hill AFB. The notices of availability for
these documents were published in the Salt Lake Tribune. A public comment period was
held from February 20, 1995, through March 21, 1995. In addition, a public meeting was
held on March 1, 1995. At this meeting, representatives from Hill AFB, EPA, and the
State of Utah answered questions about the site and the selected remedy. A court reporter
prepared a transcript of the meeting. Copies of the transcript and all verbal public
comments received at that meeting are presented in the Responsiveness Summary of this
document for inclusionjn the Administrative Record. In addition, copies of the transcript
were sent to all meeting attendees who requested them. The decision for this site is based
on the Administrative Record.
2.5 SCOPE AND ROLE OF OPERABLE UNIT 7 WITHIN SITE STRATEGY
OU 7 is one of nine operable units at Hill AFB. The remaining operable units are at
various stages in the RI/FS process. The remedial actions planned for the various
operable units are independent of one another. This action addresses contaminated soil at
OU 7. Ground water beneath OU 7 will be addressed as part of OU 8. The remedy
selected for OU 7 will address threats to human health and the environment by requiring
that the existing floor remain intact so it will prevent direct exposure to contaminated
soil, and prevent further transport of metals to ground water. Institutional controls will
provide for maintenance of the floor and land use restrictions. Through restrictions to the
deed for the property, the restrictions will apply to both the present land use by the Air
Force, and in the future should property ownership change.
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3.0 SUMMARY OF SITE CHARACTERISTICS
3.1 NATURE AND EXTENT OF CONTAMINATION
Data summarized in this section were collected during the OU 7 RI and the preceding
Building 225 site characterization effort. Table 3-1 shows the maximum concentrations
of chemicals detected during these investigations at the various OU 7 sites including
Buildings 225 and 220, and Base Supply Well 6.
Beneath the former Metal Plating Shop, which is currently covered by the concrete floor
inside of Building 225, hexavalent chromium and cadmium were detected. Figures 3-1
and 3-2 show the lateral distribution of these metals in the subsurface soils, and
Figure 3-3 shows the vertical distribution of hexavalent chromium. The highest
concentrations generally occurred in the uppermost layer, found at approximately 10 feet
below the ground surface, as shown in Figure 3-3. Hexavalent chromium was detected as
deep as 90 feet below the ground surface. Cadmium was detected only in the upper 10
feet of soil.
Mercury was detected sporadically as deep as 90 feet below the ground surface, having
been detected in five of 30 samples. It was never detected in background samples. Other
metals were detected at concentrations elevated relative to background, but only by a
small amount (as indicated by the fact that the average site concentration was less than
twice the average background concentration). Cyanide was detected in two of 35
samples at a maximum depth of 6 feet below ground surface.
Low concentrations of several VOCs also were detected in soil beneath the former Metal
Plating Shop. These chemicals generally were found in the clay layer at 10 feet, although
trace concentrations of one VOC were detected as deep as 80 feet below the ground
surface.
In the PCB spill area, detections of PCBs and alpha and gamma chlordane were sporadic.
Only two of 36 samples contained detectable concentrations of PCBs. Both PCB
detections were in soil samples collected from 0.8 to 2 feet below ground surface, and
were at the perimeter of the soil removal performed in 1989. Three of the 36 soil samples
contained low but detectable concentrations of chlordane. These three samples ranged in
depth from 0.8 to 12 feet below ground surface.
At the Miscellaneous Areas inside of Building 225, only trace concentrations of several
VOCs, fuel hydrocarbons, and metals were detected in soil samples. The fuel
hydrocarbons were detected in only two samples and were tentatively identified as a
hydraulic fluid. Aluminum, arsenic, barium, cobalt, nickel, and tin were present in most
or all samples, with average concentrations at least twice those observed in background
samples. The highest concentrations of these metals all were in the upper 12 feet of soil.
All detections of contaminants in the Miscellaneous Areas were in soil samples collected
from less than 12 feet below ground surface.
3-1
-------
TABLE 3-1
CHEMICALS DETECTED IN OU 7 SOURCE AREAS
Maximum Source Area Concentrations (mg/kg)
Former Metal PCB Spill
Chemicals
Inorganic Chemicals
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium (total)
Chromium (VI)
Cobalt
Copper
Cyanide
Lead
Mercury
Nickel
Silver
Tin
Vanadium
Zinc
Volatile Organic Compounds (VOCs)
Chloroform
1,1 -Dichloroethane
1,1-Dichloroethene
Methyl ethyl ketone
Tetrachloroethene
Toluene
1,1,1 -Trichloroethane
Trichloroethene
Trichlorofluoromethane
Xylenes
Plating Shop
3,390
6.8
78.4
0.33
220
2,900
1,600
2.6
149
1.4
43.5
0.43
6.5
3.8
ND
7.7 -
172
ND
ND
ND
0.0067
ND
ND
0.0048
0.069
0.0027
ND
Area
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Building 225
Misc. Areas
4,610
8.9
68.6
0.59
ND
8.2
0.72
17.8
46.3
ND
16.6
ND
9.3
1.3
27.6
13.8
28.0
ND
ND
ND
ND
ND
0.0072
0.0063
0.0089
ND
ND
Base Supply
Well 6
3,250
2.9
39.1
0.29
0.54
7.6
ND
2.0
6.7
6.3
52.9
0.24
6.7
2.0
ND
8.2
23.2
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Building 220
-
6,890
9.7
149
0.67
8.3
41.7
0.094
5.0
74.8
ND
25.7
0.068
637
ND
47.1
16.3
83.3
0.0017
0.021
0.018
0.02
0.0032
17
0.91
0.0039
0.002
2.4
Semivolatile Organic Compounds, Pesticides,
PCBs, and Furans
Chlbrdane
Chlorinated dibenzofurans
Di-n-butylphthalate
Di-n-octyphthalate
PCBs
Phenol
1 ,2,4-Trichlorobenzene
ND
ND
ND
ND
ND
ND
ND
ND Chemical not detected at or above the method
NA Chemical not analyzed for this o
ompound
0.0047
NA
NA
NA
0.23
NA
NA
detection limit
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.0000054
0.53
2.1
0.14
0.83
0.57
3-2
-------
1
CM
6
DC
Q.
A t 10
A U7-707
Chromium Plating
\ Silver Plating
(Central Area)
...I II
EXPLANATION
Chromium Plating
(South Area)
U7-OW
Boring location and
U7-728 number
Background boring
U7-703 location and number
Monitoring well location
U7-008 a"11 number
n Boundary of old metal
nlatina areas
/ Existing aircraft
/ maintenance stalls
(60) Stall number
,.- Isoconcentration contour
- (mg/kg)
(dashed where inferred)
Cross section A-A'
HILL AIR FORCE BASE
OPERABLE UNIT 7
BUILDING 225
ISOCONCENTRATION MAP FOR
HEXAVALENT CHROMIUM IN SOIL
FIGURE 3-1
0 10 20 30 40 50
*=
Scale in Feet
-------
pQmerT Kin 2208.0875
fs
EXPLANATION
Boring
U7-728 numb*
ฎ Backg
U7-703 locatic
-^- Monitc
U7-008 and ni
n Bound
plating
/ Existin
/ mainte
(60) Stall n
v ^ Isocon
-"1- (mg/kc
(dashe
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
N
location and
x
round boring
n and number
>ring well location
jmber
any of old metal
areas
g aircraft
>nance stalls
umber
centration contour
))
id where inferred)
(60)
/
(59)
f
U7-704
(58)
/
U7-701
ฉ
.^ ! -* ^/l "- U7-707
/U7-706/ jj- U7_728
>. 11 "^Chromium/Cadmium P
;' (North Area)
/
/
f"
f
U7-718 ^
Cadmium
U7-720
V /
"*"'-^-*.
ฎ U7-703
(Central Ar
\
V
U7-717
U7-719
U7
Plating
ฎ U7-705
.
71
\
\
\
\ U7-702
\ ฉ
lating \
\
(61)
\
U7-708
V- :-; ..-;:
Chromium PEatin
^117-729 1
U7-710
; ~ ^ -
' *-;: :'""' . $
ea) ' / " '*' -.
^^ ;U7-712
U7-713
Silver Plating
(63)
\
\
\
U7-714 ซ\
U7-730
Chromium Plati
\ (South Area)
\. U7-008
rปy\U7^716ซ
\
\ c :
c .
B ' "'
C.
\ c .
V
\
:r -v.
"""^x.
\
ng \
V t
)^/
i"ift\
\r
L
P
M
i
., ...i
i
i
HILL AIR FORCE BASE
/ - \ OPERABLE UNIT 7
9 10 20 30 40 50 A/CM BUILDING 225
=t^=^=i=i ri^ry ISOCONCENTRATION MAP
ScaIeinFeet ^~S FOR CADMIUM IN SOIL
FIGURE 3-2 /
-------
PROJECT NO. 2208.0875 9/6MS
Area of former metal plating operations
U7-710 U7-711 U7-712 U7-714
EXPLANATION
n Coarse-grained sediments
(sand and silty sand)
- ...I.
I I Fine-grained sediments
{clay, silt, and sandy silt)
Area of attainment
Ground-water level
, Area of former metal plating
operations
Cr6' 1-10 ppm
Cr6* 10-100 ppm
Cr^lOOppm
Groundwater contaminated with
Cr6* (addressed by OU 8)
HILL AIR FORCE BASE
OPERABLE UNIT 7
GEOLOGIC CROSS SECTION
kDnnen MJICTAI ni ATIKI/^ ourt
* 140
GEOLOGIC CROSS SECTION
OF FORMER METAL PLATING SHOP AREA
SHOWING VERTICAL DISTRIBUTION OF
HEXAVALENT CHROMIUM CONTAMINATION
FIGURE 3-3
-------
Soil samples from the backfill placed at Base Supply Well 6 contained average
concentrations of lead, mercury, nickel, and cyanide that were at least twice their average
background concentrations. Lead, mercury, and nickel were detected in all three samples
from this site; cyanide was detected in two of three samples.
Samples of soil from beneath Building 220 contained several organic compounds and
metals above natural background conditions, although all of the contaminants were
detected in low concentrations. The organic compounds included VOCs, fuel
hydrocarbons, semivolatile organic compounds (SVOCs), PCBs, and chlorinated
dibenzofurans. The VOCs were found at low concentrations in soil samples from several
locations inside and outside of Building 220, and to depths up to 62 feet below ground
surface. The fuel hydrocarbons were tentatively identified as gasoline and other
unknown, degraded fuel hydrocarbon components. The fuel hydrocarbons were only
detected in the upper 12 feet of soil. In one sample from beneath the former separator
tank locations (12 to 14 feet below ground surface), several SVOCs, PCBs, and
chlorinated dibenzofurans were detected in low concentrations. A soil boring and
monitoring well installed through the Building 220 Source Area, found that soil
contamination was limited in depth and had not reached the ground water.
Metals present above background with an average site concentration at least twice the
average background concentration included chromium, hexavalent chromium, and
mercury. Chromium was present in all soil samples. Its maximum detected
concentration was in the same sample where SVOCs, PCBs, and chlorinated
dibenzofurans were detected. Hexavalent chromium was detected in 3 of 86 samples.
All three of these samples were within 12 feet of the ground surface. Mercury was
detected in eight out of 86 samples to a maximum depth of 82 feet below ground surface.
3.2 SUMMARY OF FATE AND TRANSPORT OF CONTAMINANTS
A conceptual site model, depicting the OU 7 source areas and the contaminants and
routes of contamination migration associated with each area, is shown in Figures 3-4 and
3-5. Metals and other chemicals seeped into the soil beneath OU 7 in wastewater
solutions. These discharges have been stopped because of building renovations and the
soils subsequently have dried out. The metals and other chemicals remain in the soils
mainly as precipitates and are not expected to become mobile again without percolating
water to act as a transport medium. Figure 3-4 illustrates the spatial relationship in the
conceptual model using a block diagram of the site, and Figure 3-5 illustrates the
transport pathways and contaminants in each area. Specific characteristics and processes
that affect the fate and transport of OU 7 contaminants in soil, water, and air are
summarized in the RI/FS for OU 7 (Montgomery Watson, 1995).
Fate. Numerous types of environmental contaminants were detected in the OU 7 soil.
These include VOCs, BNAEs, pesticides/PCBs, furans, elevated metals, and cyanide. Of
these, natural degradation of non-chlorinated VOCs, some BNAEs, and cyanide is
expected to occur fairly rapidly. By contrast, some BNAEs, chlorinated VOCs,
pesticides/PCBs, furans, and metals tend to persist in the soil.
3-3
-------
PROJECT NO. 2208.0875
PATHWAY
Building 225 subsurface soil contamination
Building 225 shallow ground-water contamination
Building 220 subsurface soil contamination
Building 220 shallow ground-water contamination
CONTAMINANTS
Metals, VOCs, Cyanide. TPH. Pesticides, PCBs
Metals. VOCs, TPH
VOCs, BNAEs. Metals, PCBs, Furans
None
Base supply Well 6 shallow surface soil contamination Metals, Cyanide
Predominent pathway
Minor pathway
Unlikely pathway
Soil Gas
Zone of contamination
HILL AIR FORCE BASE
OPERABLE UNIT 7
GENERALIZED CONCEPTUAL
MODEL OF CONTAMINANT TRANSPORT
FIGURE 3-4
-------
PROJECT NO. 2208.0875
fit
AIR
Building 225 Metal
Plating Shop and
Transformer Vault
Chlorinated
Solvents, Metals,
Cyanide, PCBs,
Pesticides
Soil Gas
Building 225
Miscellaneous
Areas
Chlorinated
Solvents,
Hydraulic Fluid,
Metals
Soil Gas
Building 220
Paint Stripping
Operation
Chlorinated Solvents,
Fuels, High Boiling
Point Organic
Compounds, Oils
Base Supply
Well 6
Metals, Cyanide,
(from Bldg. 225)
SOIL/UNSATURATED ZONE
Chromium, Cadmium, Arsenic,
Beryllium, Lead. Cyanide, TCE. TCA,
MEK. TCFM, PCBs, Chlordane
TCA, TCE. Toluene, Arsenic,
Beryllium, Chromium, Hydraulic Fluid
TCE, DCA, DCE, TCE, PCE. Xylene,
Toluene, MEK, Hydraulic Fluid.
Phenol, Trichlorobenzene, Phthalates,
PCB-1260, Furans, Chromium.
Arsenic, Beryllium, Nickel
Cyanide, Arsenic, Beryllium, Lead
i
i
y
SHALLOW GROUND WATER (ON BASE)
TCE, DCE, TCA, PCE, Chloroform, Oichlorobenzene,
Arsenic, Chromium, Lead, Petroleum Hydrocarbons
Not Evaluated
I I
I
I
Predominant Minor Unlikely Pathway
Pathway Pathway (not thought to occur
based on available data)
Soil Gas
NOTE: All metals that trigger a health risk, cyanide, and all organic
contaminants detected in source areas are listed.
HILL AIR FORCE BASE
OPERABLE UNIT 7
CONCEPTUAL MODEL OF PAST
CONTAMINANT TRANSPORT
FIGURE 3-5
-------
Transport The least mobile compounds detected at OU 7 are pesticides/PCBs, BNAEs,
furans, and most metals due to their relatively strong sorptive nature. There is no
evidence that the soil currently is high in moisture or that other fluids are present.
Consequently, those more soluble and less sorptive compounds such as VOCs, cyanide,
and hexavalent chromium that could mobilize under water-saturated conditions are not
expected to be transported further under current conditions. If conditions change and
fluids are introduced, these chemicals could be transported through the subsurface soil to
ground water. To quantitatively determine if these chemicals could be transported to
ground water, an equilibrium partitioning model was used. The results of this model
showed that only hexavalent chromium was in sufficient concentrations to be transported
to ground water. See Section 5.0 of this ROD and Section 7.0 of the OU 7 RI/FS
(Montgomery Watson, 1995) for more details of how the equilibrium partitioning model
was used.
3-4
-------
4.0 PUBLIC HEALTH AND ENVIRONMENTAL IMPACTS
4.1 HUMAN HEALTH
A baseline risk assessment (BRA) was prepared for OU 7 as part of the RI/FS
(Montgomery Watson, 1995). The purpose of the risk assessment was to identify the
contaminants of concern present at OU 7, the current and future exposure pathways for
humans and environmental receptors, and the probability of the occurrence of harmful
effects resulting from current and future exposures. Based on the data collected and the
risk assessment results, the medium of concern at OU 7 is the shallow soil (0 to 12 feet
below ground surface). The primary contaminants of concern for this medium are
hexavalent chromium and cadmium. These compounds are the primary contaminants of
concern because they are the most prevalent contaminants at the site and contribute most
to the risks. The current risks to human health due to OU 7 contamination are well below
levels considered significant by EPA. The areas of contamination are beneath concrete
floor slabs under existing buildings, which prevent exposure to humans and the
environment. Also, the buildings and surrounding asphalt- and concrete-covered areas
act as a barrier to precipitation and other fluids that could carry the contaminants from the
soil to the ground water below. It is anticipated that Hill AFB will remain an active
facility under Air Force control for the foreseeable future. As long as the buildings
remain at OU 7, future cancer and noncancer health risks are insignificant through direct
exposure routes. However, it is also possible that the Base could be closed and the
current facilities and buildings removed. In that case, future residential housing could be
built on the site, which could expose construction workers and residents to unhealthy
levels of heavy metals through inhalation and ingestion of contaminated soil.
4.1.1. Contaminant Identification
The initial step of the risk assessment was to select the contaminants of concern, which
are toxic substances that have the potential to come in contact with environmental
receptors. Contaminants of concern were chosen for each of the source areas at OU 7 and
were based upon frequencies of detection, concentrations, and toxicities for the relevant
exposure pathways. The data used to select contaminants of concern for shallow soil
were from soil samples collected within 12 feet of the ground surface. The data used to
select contaminants of concern for surface soil were from soil samples collected within
2 feet of the ground surface. A summary of the contaminants of concern for soil in the
OU 7 source areas is presented in Table 4-1. A detailed breakdown of the contaminants
of concern according to specific OU 7 source areas is included in the RI/FS for OU 7
(Montgomery Watson, 1995).
4.1.2. Exposure Assessment
An exposure assessment was performed to identify current and potential future exposure
pathways through which contaminants of concern could travel to environmental
receptors. The ground-water exposure pathway was not assessed in the OU 7 BRA;
however, it will be addressed as part of the OU 8 BRA. A summary of this assessment is
provided below. A more detailed discussion is included in the BRA, which is Section 6.0
of the RI/FS for OU 7 (Montgomery Watson, 1995).
4-1
-------
TABLE 4-1
HILL OU 7 CHEMICALS OF CONCERN FOR SOIL
Type of Chemical
Metals
Poly Chlorinated Biphenols
Pesticides
Volatile Organic Compounds
Compound
Arsenic
Barium
Beryllium
Cadmium
Chromium VI
Chromium HI
Mercury
Nickel
Silver
Vanadium
PCB-1254
PCB-1260
alpha-Chlordane
gamma-Chlordane
Toluene
NC
-------
Current. Potential current exposures at OU 7 are associated with two media: surface
soil (0 to 2 feet below ground surface) in uncovered areas, and air. Possible exposures by
current maintenance personnel, who could inhale or ingest contaminated dust or have
dermal contact with contaminated soil would only occur if excavating into soil. This is
considered unlikely because no excavation into soils is needed because the utilities in
Building 225 are located within concrete-lined trenches and the utilities within Building
220 are located above ground.
The degree of exposure to surface soils in uncovered areas of OU 7 depends on the
amount of vegetation (that may prevent or limit exposure) present at each of the areas.
The open areas east of Building 220 and around Base Supply Well 6 are located near the
flight line, where access is limited, and generally are covered with vegetation. The only
possible exposure to soil in these areas would be to maintenance workers that cut the
grass. However, the exposure would be limited because these areas are small and the
grass is cut only twice each year. Because of the vegetative cover over the open areas of
OU 7 and the limited potential for exposure of current workers through incidental contact
with contaminated soil, inhalation of fugitive dust, and ingestion and dermal contact with
contaminated soil were not evaluated under current conditions.
No known sources of contaminant emissions to the air currently exist at OU 7.
Volatilization from the soil into the air is considered to be very minor at OU 7, especially
in areas that are covered with concrete or asphalt. The exposure assessment concluded
that no current exposure pathways are complete because areas with contaminant
concentrations in soil considered significant by EPA are located beneath existing concrete
floor slabs.
Future. For future land use scenarios, it was assumed that residential, commercial, and
industrial development could take place within the current boundaries of Hill AFB. If
Hill AFB is closed, residential, commercial, and industrial operations would most likely
replace the existing uses, although there are no current plans to close the Base. Complete
removal of the heavy industrial infrastructure in the OU 7 area, followed by returning the
land to farming, is considered highly unlikely. If Hill AFB is closed, potential future land
use in the OU 7 area may be similar to the current residential land use in the area of
Layton, next to the Base. Potential future exposures at Hill AFB would be associated
with two media: soil (within 12 feet of the surface), and air.
Under potential future land use, residential, commercial, and industrial operations may be
developed within the present boundaries of Hill AFB. Where construction does occur,
shallow soil near the surface (to a depth of 12 feet) might.be considered as a potential
exposure route because foundation and basement construction could penetrate to this
depth (i.e., construction workers building homes and industrial or commercial buildings
may become exposed to shallow soil during construction activities). Three exposure
routes were considered for construction workers: incidental ingestion, inhalation of
fugitive dust, and dermal contact with soil and fugitive dust. However, employees of
future commercial or industrial operations were assumed to have no exposure to soil for
two reasons: most employees were assumed to spend their working time indoors, and
4-3
-------
paved land surfaces at these operations will prevent exposure to soil among those
employees who do work outdoors. Like construction workers, persons living in
residential developments could be exposed to chemicals in surface soil (to a depth of
2 feet) via three exposure routes: (1) incidental ingestion of soil (where food may be
ingested with unwashed hands or unwashed hands may be placed in the mouth),
(2) inhalation of fugitive dust from areas of exposed surface soil such as gardens, and
(3) dermal absorption as a result of dermal contact with surface soil or fugitive dust on
exposed skin.
There are no known current emissions to the air at OU 7. Soil gas surveys were used to
qualitatively identify potential soil contamination by VOCs in order to select locations for
soil borings. Samples from those borings showed low to no detectable concentrations of
volatiles in soil. Under the current exposure scenario, volatilization from the soil into
outdoor air is considered to be minor relative to other exposures. The concentrations at
points of potential human exposure are expected to be extremely low. No evidence
suggests that the potential for volatile emissions will change in the future.
For more details regarding the assumptions, models, and parameters used to estimate the
concentrations at the receptors and the chronic daily doses for each exposure pathway,
reference is made to the BRA, Section 6.0 of the RI/FS for OU 7 (Montgomery Watson,
1995).
4.1.3. Toxicity Assessment
Slope factors (SFs), are used to provide conservative estimates of excess lifetime cancer
risks associated with exposure to potentially carcinogenic chemicals. Slope factors are
derived from the results of human epidemiological studies and chronic animal bioassays
to which animal-to-human extrapolation and uncertainty factors have been applied.
Reference doses (RfDs) are used to indicate the potential for adverse effects from
exposure to chemicals exhibiting non-carcinogenic effects. RfDs are estimates of
lifetime daily exposure levels for humans, including sensitive individuals, which are
compared to estimated intakes of chemicals from environmental media. RfDs are derived
from human epidemiological studies and animal studies to which uncertainties have been
applied. SFs and RfDs for the contaminants of concern at OU 7 are presented in
Tables 4-2 and 4-3. The most toxic compounds present at OU 7 are hexavalent
chromium and cadmium. These compounds are the most prevalent contaminants of
concern, and they pose both carcinogenic and noncarcinogenic health risks. Contaminant
toxicity is discussed in detail in the BRA (Montgomery Watson, 1995).
4.1.4. Risk Characterization
Cancer and noncancer risks were calculated for each of the exposure pathways using
reasonable maximum exposure estimates for the potential contaminants of concern. The
results of these calculations were compared to acceptable levels of risk. For carcinogenic
exposures, an excess lifetime cancer risk of 1 x 10~6 indicates a one in a million chance
that an individual will develop cancer after being exposed to a carcinogen under the site-
4-4
-------
TABLE 4-2
SUMMARY OF SLOPE FACTORS FOR POTENTIAL CONTAMINANTS OF CONCERN
VOCs
Compound
2-Butanone (MEK)
1,1-Dichloroethene
Perchloroethylene
Toluene
1,1,1-Trichloroethane
Trichloroethene
Trichlorofluoromethane
Xylenes, Total
Ingestion
Slope Factor
(mg/kg/day)'1
0.6
5.1x10 =
'
1.1x10 =
Ingestion
Weight of
Evidence
D
C
B2
D
D
B2
D
Source
I
I
STSC
I
I
STSC
I
Inhalation
Slope Factor
(mg/kg/day)-1
--
1.20
2xlOs
6xlOJ
-
Inhalation
Weight of
Evidence
D
C
B2
D
D
B2
D
Source
-
I
H
STSC
I
I
STSC
I
Pesticides and PCBs
Inorganic
(a)
VOCs
PCBs
I
H
STSC
alpha-Chlordane
gamma-Chlordane
PCB-1254
PCB-1260
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium VI
Chromium III
Cobalt
Copper
Lead
Manganese
Mercury
Nickel Ca)
Silver
Tin
Vanadium
Zinc
Cyanide
Values are for nickel refinery
Volatile organic compounds
Polychlorinated biphenyls
1.3
1.3
7.7
7.7
1.8
4.3
-
-
~
.
-
~
dust.
B2
B2
B2
B2
A
B2
D
D
~
D
B2
D
D
D
---
D
I
I
I
I
I
I
H
1
I
I
I
I
1
I
1.3
1.3
15.0
8.4
6.3
41.0
-
-
0.84
B2
B2
B2
B2
A
B2
Bl
A
D
B2
D
D
A
D
D
I
I
I
I
1
1
I
I
0
I
IRIS database searched in March 1994
Health Effects Assessment Summary Tables (HEAST. 1993)
Superfund Technical Support
Center
Not available on IRIS, HEAST, or from the Superfund Technical Support Center
mg/kg/day milligrams per kilogram per day
A Human carcinogen
B1 Probable human carcinogen, based on limited human data
B2 Probable human carcinogen, based on animal data
C Possible human carcinogen
D Not classified
4-5
-------
TABLE 4-3
ซ
REFERENCE DOSES
ON
Compound
Benzene
Chloroform
1,1-Dichloroethene
1 ,2-Dichloroethane
1,2-Dichloroethene (trans)
1,2-Dichloroethene (cis)
Methyl Ethyl Ketone
Tetrachloroethene
Toluene
Trichloroethene
Xylenes
Arsenic
Barium
Boron
Cobalt
Nickel
Selenium
Chronic Oral
Reference Dose Uncertainty
(mg/kg/day) Factor Source
NA
1 x 10-2
9x 10-3
NA
2x10-2
1 x 10-2
6x 10-'
1 x 10-2
2x 10-'
7x 10-3
2x 100
3x lO'4
7x 10-2
9x 10-2
NA
2x 10-2
0.005
NA No information or data were available
LHA Lifetime Health Advisory
IRIS Integrated Risk Information System,
searched March and July 1993
NA
1,000
1,000
NA
1,000
1,000
3,000
1,000
1,000
NA
100
3
3
100
NA
300
3
HEAST
P
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS
IRIS
IRIS
LHA
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Chronic
Inhalation
Reference Dose Uncertainty
(mg/kg/day) Factor
1 x lO-3
2x 10-3
5x 10-3
NA
NA
NA
2.9 x 10-'
NA
1.1 x lO-1
NA
9x lO-2
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1000
NA
100
NA
100
NA
NA
NA
NA
NA
NA
Source
P
P
P
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
NA
IRIS
IRIS
IRIS
IRIS
~
IRIS
IRIS
Health Effects Assessment Summary Tables, 1993
Proposed RfD, Hazardous Pollutant Assessment Branch,
Environmental Criteria and Assessment Office, EPA
Not Listed in HEAST or IRIS
-------
specific conditions for a 70-year lifetime. The target excess lifetime cancer risk is
1 x 10~6 (one in one million) and the maximum limit for excess lifetime cancer risk is
1 x lO"4 (one in ten thousand). For exposures to noncarcinogenic compounds, a total
hazard index greater than one is considered to be an unacceptable risk.
For potential future exposure scenarios, risks were calculated for the construction worker
scenario and the residential scenario. The construction worker scenario assumes
exposure to shallow soil (from the surface to 12 feet bgs) while the residential scenario
assumes exposure to the top two feet of soil only. Current surface soil exposure was not
quantified because the potential for, and possible duration of, exposure are minor
compared to other pathways evaluated in the BRA (e.g., future residential). The risk
estimates for future exposure pathways for soil contaminants at all of the OU 7 source
areas are presented in Table 4-4. The following discussion focuses on the cancer risks;
the hazard indices at all sites were below the benchmark of 1.
The former Metal Plating Shop site was divided into three distinct areas for risk
characterization. These areas included the North Area, South Area, and Central Area.
The estimated excess cancer risk for future construction workers is 8 x 10"^ (8 in one
hundred thousand), 3 x 10"^ (three in ten thousand), and 2 x 10~6 (two in one million) for
these three areas, respectively. These risk values are due to inhalation exposure to
hexavalent chromium. For future residents, the risk estimates were 2 x 10"^ (two in one
hundred thousand) for the North and South Areas, and 1 x 10*6 (one in one million) for
the Central Area.
The other sites evaluated for construction risk characterization at OU 7 include the PCB
Spill Area, Base Supply Well 6, Miscellaneous Areas inside Building 225, and the
Building 220 area. For construction workers, the only one of these areas with a
potentially significant cancer risk is the Building 225 Miscellaneous Areas, where the
estimated risk was 3x10"^ (three in one million) from arsenic and nickel. Cancer risks
for the construction worker for all other sites were less than the 1 x 10~6 benchmark (see
Table 4-4).
All of the results for the residential risk characterization at these other OU 7 sites were
above the 1x10"" benchmark. For the PCB Spill area, the estimated excess cancer risk
is 3 x 10~6 (three in one million); for the Base Supply Well 6 area, the estimated excess
cancer risk is 4 x 10"6 (four in one million); for the Building 225 Miscellaneous Areas,
the estimated excess cancer risk is 3 x 10'5 (three in one hundred thousand), and for the
Building 220 area, the estimated excess cancer risk is 2 x 10'6 (two in one million).
4.1.5. Uncertainties
The risk estimates cited have uncertainties associated with them. There are uncertainties
in the risk factors (i.e., the slope factors and reference doses), in the risk summation, the
exposure parameters, the projected land use, and the chemicals present. Most risk factors
are based on animal data. To extrapolate to humans, uncertainty or safety factors are
4-7
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TABLE 4-4
SUMMARY OF CANCER RISKS AND HAZARD INDICES
BY PATHWAY: FUTURE EXPOSURES
oo
Cancer Risk
Scenario
FUTURE - Reasonable Maximum Exposure
Soil On Base, Construction Workers
Former Building 225 Metal Plating Shop - North Area
Former Building 225 Metal Plating Shop - South Area
Former Building 225 Metal Plating Shop - Central Area
Building 225 PCB Spill
Base Supply Well 6
Building 225 Miscellaneous Areas
Building 220
Soil On Base, Residents
Former Building 225 Metal Plating Shop - North Area
Former Building 225 Metal Plating Shop - South Area
Former Building 225 Metal Plating Shop - Central Area
Building 225 PCB Spill
Base Supply Wejl 6
Building 225 Miscellaneous Areas
Building 220
Ingestion
NC
NC
NC
3x10"
8x10"
7x10'
NC
NC
NC
NC
1x10"
2xl06
2x10'
2x10"
Inhalation
8x10'
3x10"
2x10"
6x10"
5x10"
2x10"
IxlO'
2x10'
2x10"
1x10"
3x10"
2x10"
8x10'
1x10'
Dermal
NC
NC
NC
2x10'
IxlO'
8x10'
NC
NC
NC
NC
2x10"
2x10"
1x10'
5x10"
Total
8x10'
3x10"
2x10"
5x10"
1x10'
3x10"
1x10'
2x10'
2x10'
1x10"
3x10"
4xlOซ
3x10'
2x10"
Ingestion
IxlO'
2x1 0'1
6x10'
9x10'
3x10'
5xl02
8x10"
4xl02
6xl02
7x10'
2x10"
5x1'
7x10'
4x10'
Hazard
Inhalation
NC
2x10'
NC
NC
3x10'
4x10'
2x10"
NC
IxlO4
NC
NC
8x10'
IxlO'
9x10' '
Index
Dermal
2x10"
2x10'
7x10"
3x10'
4x10'
6x10'
IxlO'
IxlO3
IxlO3
2x10"
1x10"
2xl03
6x10'
IxlO"
Total
1x10'
2x10'
6xl03
IxlO"
3x10'
9x10'
IxlO3
4xlO!
6x10'
7xl03
3x10"
2x10"
IxlO'
IxlO2
alculated
-------
included in the reference doses, and the slope factors are based on a conservative
interpretation of the dose-response curve obtained from the animal data. The risks were
assumed to be additive; any antagonistic or synergistic effects were not quantitatively
accounted for. Exposure parameters, such as the frequency, duration, and the amount of
intake or contact, were selected so that the potential for underestimating exposure was
small. The risk estimates were based on two projected land uses (i.e., construction and/or
residential). If these land uses do not occur, the risk estimates will not reflect the actual
potential risks at OU 7. The chemicals present on site have been assumed to be the ones
detected during the field sampling program. If there are continuing sources of
contamination or if chemicals such as TCE or PCE degrade in the environment, risks
could be underestimated.
In general, the methodology used in the risk assessment tends to overestimate the
potential risks. Conservative health-protective assumptions were made for exposure
duration, dosage, toxicity, and absorption. The exposure scenarios were conservative and
represented activities that might occur in the future. Overall, the methodology used for
this risk assessment makes it unlikely that the true risks are higher than the calculated
risks.
4.2 THREATS TO THE ENVIRONMENT
4.2.1. Surface Water, Ground Water, and Wetlands
No streams, rivers, or lakes exist on Hill AFB. Numerous wetlands have been identified
on Hill AFB, but none occur within 400 feet of OU 7. No impacts to surface waters or
wetlands are known as a result of contaminants at OU 7.
4.2.2. Vegetation
Vegetation in the vicinity of Operable Unit 7 primarily consists of small strips of grass.
Contaminants at Operable Unit 7 primarily are beneath buildings where they cannot
affect vegetation; therefore, no adverse effects on the local ecosystem are anticipated.
There are no endangered or threatened plant species on Base; therefore, no adverse
effects on these species in the local ecosystem will occur.
4.2.3. Wildlife
Hill AFB does not provide critical or important habitat for any wildlife species, and no
threatened or endangered species are known to inhabit the Base. Operable Unit 7 and the
surrounding areas are already developed, and the remedial activities and additional
human presence will add no significant impact to wildlife.
4.2.4. Air Quality
The contaminants at OU 7 are in subsurface soil (primarily beneath buildings) and do not
have a substantive effect on air quality.
4-9
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4.23. Archaeological Resources
There are no known cultural or archeological resources on Hill AFB in the vicinity of
OU 7.
4.3 SUMMARY OF SITE RISKS
Exposure to chemicals at OU 7 has the potential to arise if the concrete slab is removed
from Building 225. A cancer risk above 1 x 10"4 was estimated for future construction
workers for the Building 225 South Area. All other areas of Building 225 have estimated
cancer risks between 1 x 10~4 and 1 x 10~6 for future construction workers and residents.
These risks are primarily from hexavalent chromium and (to a lesser extent) cadmium.
Potential future risks between 1 x 10~4 and 1 x 10~6 also were calculated for construction
workers and residents for the Building 225 Miscellaneous Areas. At all other sites, the
cancer risk was between 1 x 10~4 and 1 x 10"^ for potential future residents but less than
1 x 10 "6 for the construction worker. It should be emphasized that these all are potential
future risks. There are no current health risks at OU 7 because the areas of contamination
are beneath concrete floor slabs under existing buildings which prevents exposure from
occurring.
Contamination at OU 7 does not pose an ecological risk to plants or wildlife. This is due
to the fact that OU 7 primarily is covered by buildings, concrete, and asphalt, and
contaminants are only in subsurface soil. A qualitative evaluation did not indicate a
significant potential for ecological threats to exist.
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and
substantial endangerment to public health, welfare, or the environment.
4-10
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5.0 DESCRIPTION OF ALTERNATIVES
As part of the feasibility study (FS) for OU 7 (Montgomery Watson, 1995), five specific
remedial alternatives were developed for soil cleanup to meet the remedial action
objectives (RAOs) for contaminated soils beneath the former Metal Plating Shop in
Building 225. Under Section 121 of CERCLA, a selected remedial action must be
protective of human health and the environment, and it must comply with applicable or
relevant and appropriate requirements (ARARs). The alternatives for soil cleanup were
evaluated for short-term effectiveness; long-term effectiveness and permanence,
reduction of toxicity, mobility or volume through treatment; technical and administrative
implementability; and cost effectiveness. Alternatives were then compared against these
criteria for selecting the recommended remediation measures. Additionally, State and
community acceptance were also required before selection of the remedy. This section
summarizes how the remedy selection process for OU 7 addressed these requirements.
5.1 DEVELOPMENT OF ALTERNATIVES
Remedial alternatives were developed by assembling technologies into combinations that
are applicable for the medium of concern at OU 7 (soil). The steps that were used to
develop remedial alternatives for OU 7 included development of response objectives,
remedial action objectives, and general response actions for contaminated soil, followed
by a preliminary screening and evaluation of technologies and process options. Response
objectives include prevention of human exposure to contaminated soil through direct
contact, ingestion, or inhalation, and long-term attainment of shallow ground-water
remedial action objectives. RAOs were developed to define the extent of the remedial
action. The RAOs for OU 7 include:
Reduce contaminant transport within source areas and reduce chemical
transport from soil to ground water by minimizing surface water infiltration.
Prevent human exposure to contaminated soil through ingestion, inhalation,
and dermal contact, such that the additional risk to an individual for cancer is
below 1 x 10~6 and the threshold non-cancer hazard index is less than 1.0.
Reduce contaminant concentrations to meet risk levels and/or reduce
contaminant transport to rates that will not impact ground-water quality above
Maximum Contaminant Levels.
Included within the RAOs are preliminary remedial goals, areas of attainment, and
estimated restoration time frames. The preliminary remedial cleanup goals are shown in
Table 5-1 and are based on health risks and on the contaminants potential to leach to
ground water. The remedial cleanup goals for shallow soils (i.e., the upper 12 feet) were
determined using risk-based concentrations from calculated risk factors (see the BRA,
Section 6.0, of the OU 7 RI/FS; Montgomery Watson, 1995). Cadmium and hexavalent
chromium, in the vicinity of the former Metal Plating Shop in Building 225, were
determined to exceed these risk-based concentrations (RBCs) in the shallow soils. For
soils deeper than 12 feet and to determine if ground-water quality standards could be
5-1
-------
TABLE 5-1
PRELIMINARY REMEDIAL GOALS FOR SOIL AT OU 7
Contaminants
Risk-Based
Preliminary
Remedial Goals )
(mg/kg)
Cadmium
Hexavalent chromium
7.57
1.16
NM
13 to 1017
53.9
348
Only compounds requiring cleanup are listed.
NM Cadmium not expected to be mobile in soil under normal pH conditions.
(a) Risk-based preliminary remediation goals were calculated from health-based risk
levels from Tables 6-29 through 6-30 of the BRA (Section 6.0 of the OU 7 RI/FS;
Montgomery Watson, 1995).
(b) Values obtained from Table 7-1 of the FS (Section 7.0 of the OU 7 RI/FS;
Montgomery Watson, 1995).
5-2
-------
exceeded if the contaminants in the soil were transported to ground water, a chemical
equilibrium and partitioning model was used to calculate the maximum concentrations of
chemicals that could remain in soil while allowing Utah and Federal ground-water quality
standards to be met. The results of this equilibrium modeling indicated that only
hexavalent chromium was in sufficient concentrations to impact ground-water quality.
Based on the hexavalent chromium concentration that corresponds to the concentration
that would trigger a lxl(H> cancer risk (1.16 mg/kg), an area of attainment of 11,000
cubic yards was determined within the former Metal Plating Shop.
General response actions for the soil identify basic actions that might be undertaken as
part of a remedial action. Several technologies may exist for each general response
action. The preliminary screening of technologies for each general response action
involved evaluation of technical implementability. In the process option evaluation,
technically implementable technologies were evaluated with respect to effectiveness,
implementability, and cost. Details of the technologies evaluated and the evaluation
process used are presented in the FS portion of the RI/FS report (Montgomery Watson,
1995).
The alternatives assembled for the cleanup of contaminated soil begin with the no action
alternative, which is required by the NCP to be included in the comparison process.
Subsequent alternatives represent an increasing degree of technical complexity. Each
alternative contains different processes and degrees of remediation for contaminated soil.
The assembled alternatives are presented in Table 5-2.
5.2 DETAILED ANALYSIS OF ALTERNATIVES
During the detailed analysis in the OU 7 FS, each alternative was assessed against nine
evaluation criteria developed by the EPA to compare the relative performance of the
alternatives and to identify the advantages and disadvantages of each. This approach was
designed to provide sufficient information to adequately compare the alternatives, select
an appropriate site remedy, and satisfy CERCLA remedy selection requirements. The
detailed analysis of alternatives included further definition of the volumes or areas of
conta'minated soil to be addressed, the technologies to be used, and the performance
requirements associated with those technologies. Also included in the FS was an
assessment and summary profile of each alternative, and a comparative analysis among
the alternatives.
Alternative 1: No Action
As Alternative 1 implies, no remedial action would be taken. This alternative is included
as a basis for comparison with other alternatives, and consists of ground-water and soil
moisture monitoring in addition to the statutory requirement for site reviews that are
required at least every five years when hazardous substances are left in place above
health-based levels. Ground-water monitoring would include testing the ground-water
quality upgradient, beneath, and downgradient of the former Metal Plating Shop. Soil
moisture monitoring would occur within the plating shop boundaries and would reveal
5-3
-------
TABLE 5-2
DEVELOPMENT OF REMEDIAL ALTERNATIVES FOR OU 7 SOIL
V
Remedial Alternatives
General
Response
Actions
Institutional
Controls
Treatment
Extraction/
Disposal
Technology
Type
Long-term Monitoring
Program
Notice to Deed
Continuing Order from
Base Commander
Warning Signs
Soil Washing
Solidification
Excavation
(backhoc/front loader/
clamshell)
Landfill Disposal
Backfill
Alternative
1
No Action
Alternative
2
Institutional
Controls
Alternative
3
Excavation/
OIT-Site
Disposal
(off-site)
Alternative
4
Excavation/Soil
Washing/
Disposal
(ex-situ)
'
(off-site)
Alternative
5
In-Situ
Solidification
(in-silu)
-------
the potential for contaminants to leach downward, where they could eventually affect
ground-water quality.
The building and concrete slab currently act as a barrier over the contaminated soil that
limits infiltration and prevents exposure. However, removal of the building and floor
slab would allow accidental human exposures and may allow fluids to infiltrate and
threaten ground water. Removal of the building and floor slab would require a re-
evaluation of the remedial alternative because Alternative 1 would no longer be
protective of human health and the environment. Also, this alternative does not include-
provisions to limit future access to the soil beneath the former Metal Plating Shop and
development of the contaminated area. Under Alternative 1, construction workers could
be exposed to contaminated soil if they were to excavate beneath the building floor. In
addition, there are no provisions to maintain the building and floor slab.
Capital cost requirements for Alternative 1 are $108,000, and the annual operation and
maintenance for years 1 through 10 is $36,600 per year and for years 11 through 30 is
$30,900. The estimated 30-year present-value cost is $468,000.
Alternative 2: Institutional Controls
Alternative 2 includes the same elements as Alternative 1 but adds controls that will limit
access to contaminated soils that could pose significant health risks. Additional elements
of Alternative 2 include: having the Base Commander issue a continuing order that
restricts access by Air Force employees and personnel, posting warning signs, filing a
notice to the deed for Hill AFB, and in the event that ownership of the property is
transferred, specific covenants in the deed to continue restrictions and allow future
response actions, if needed. Each of these additional elements is described in further
detail below.
The continuing order would:
Restrict the installation of any new underground utilities or other construction
activities beneath the floor in the former Metal Plating Shop Area, thus
preventing accidental exposures to the construction worker.
Provide for the use of proper protective equipment if for any reason the
concrete floor slab in the former Metal Plating Shop area is to be removed.
Require that the integrity of the concrete floor slab be maintained (i.e., repair
cracks that may develop) so that fluids cannot infiltrate to the subsurface.
Maintenance of the floor slab would require development of standard
operating procedures (SOPs) to provide for inspections, floor repairs, and
responses to spills in critical areas. The continuing order would be in effect as
long as the property is owned by Hill AFB.
5-5
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Warning signs would be posted stating that hazardous chemicals are present beneath the
floor slab in the former Metal Plating Shop area and that no excavation is permitted
without proper authorization.
A notice to the deed would be filed by the Air Force in the real property records of Davis
County detailing the restrictions in the continuing order. In addition, the Air Force would
include a restrictive covenant to the deed for affected property that allows access for
maintenance and monitoring following property transfer and notifies the transferee of the
locations and restrictions on use of the affected areas.
The capital cost associated with the institutional control alternative is $184,000. The
annual operating and maintenance cost for Alternative 2 is $39,500 per year for years
1 through 10 and $33,800 per year for years 11 through 30. In addition, five-year site
reviews are anticipated to cost $25,000 every five years. The total 30-year present worth
cost of the institutional control alternative is $627,000.
Alternative 3: Excavation/Off-Site Disposal
Alternative 3 consists of excavation and off-site disposal of contaminated soil. Soil
would be excavated from areas with hexavalent chromium concentrations greater than
1.2 mg/kg, which would be protective of a construction worker and potential future
resident, as well as prevent leaching to ground water in concentrations above MCLs.
Affected soil would be removed to a depth of approximately 15 feet at the northern
chromium plating area, to 15 feet in the cadmium plating area, to 12 feet in the central
chromium plating area, and to a depth of 50 feet at the southern end of the plating shop
for a total of approximately 11,000 cubic yards of soil. Removal of the soil also would
reduce concentrations of other chemicals at OU 7 to health-protective levels. Because of
the large percentage of fine sand in the soil, the excavation walls would need to be sloped
to prevent cave-in and eliminate the need for shoring. The total volume of excavated soil,
including the 1:1 sloped walls and a small contingency for additional soil contamination,
is estimated to be approximately 30,000 cubic yards. Clean soil from either an on-Base
or off-Base source would be placed into the excavated area as backfill to replace the
removed soil.
Long-term environmental monitoring is not needed in this alternative, and no future land-
use restrictions apply because contamination would be removed from the site. The only
costs associated with this alternative are capital costs of $7,332,000.
Alternative 4: Excavation/Soil Washing/Disposal
Alternative 4, Soil Washing, would significantly reduce the volume of contaminated soil
that must be disposed off-site. The soil washing process includes excavating the
contaminated soil, treating the soil with water and chemicals, and returning the clean
portion of the soil to the excavation pit. The soil volume requiring treatment would be
the same as for Alternative 3, including sloped walls and a small volume contingency.
5-6
-------
Soil washing would involve both chemical and physical treatment. In the chemical
treatment process, the soil is suspended in an aqueous solution and the contaminants are
leached from the soil using reagents, which react with and solubilized the contaminants.
The chemical process results in transformation of the contaminants into less toxic forms.
The physical treatment process consists of separating and screening the soils to
concentrate and reduce the volume of contaminated soil/sludge that must be disposed off
site. A typical soil washing system will treat both coarse and medium-grained particles,
but is less effective in treating fine-grained soil. A separate component of the soil
washing process is necessary to treat the fine particles. Because of uncertainties
associated with this alternative, a treatability study would be needed to confirm the
effectiveness of this technology and to provide data necessary to design the treatment
system.
The concentrated sludge resulting from the fine-particle soil washing process would be
dewatered to produce a sludge cake. The sludge cake, which would be disposed off-site
at a permitted hazardous waste landfill, would have substantially less volume than the
original contaminated soil. The treated soil then would be placed back in the excavation
and compacted. Additional clean soil from either an on-Base or off-Base source would
be backfilled into the excavation and compacted, as necessary. The leachate from the soil
washing process would be discharged to the IWTP for treatment.
Because contaminants would be removed from the soil and disposed off-site, there would
be no long-term monitoring needed with this alternative. The only costs associated with
this alternative are capital costs totaling $5,221,000.
Alternative 5: In-Situ Solidification
Alternative 5 consists of in-situ solidification of the contaminated soil, environmental
monitoring, and the five-year site reviews required when hazardous substances are left in
place in concentrations above health-based levels. In this alternative, soil would be
mixed in-place with treatment agents using a specialized auger equipped with nozzles
capable of injecting the treatment agents into the soils as the auger mixes them. This
method of mixing results in a cylinder of treated soil with a diameter equal to that of the
auger, which typically ranges from 6 to 10 feet. Alternative configurations use multiple
augers that affect a rectangular footprint, approximately 4 to 6 feet across. The process is
repeated across the treatment area with each new cylinder or rectangle overlapping the
previously treated soil until the entire area of concern has been treated. A large dome
would be placed over the auger system during the mixing process to capture excess
VOCs that may escape during mixing and channel them through a granulated activated
carbon (GAC) bed before they are discharged to the atmosphere. The low levels of
VOCs detected in the subsurface soils are not expected to effect the actual solidification
process.
Typical treatment agents used for solidification include cement kiln dust, Portland
cement, hydrated lime, and fly ash. Bench tests would be necessary to determine the
most appropriate solidifying agent for the chemicals in affected soil at OU 7. A pilot test
also may be necessary to determine the most effective mix of solidifying agent, water,
5-7
-------
and contaminated soil. Pretreatment and post-treatment representative samples of the soil
cylinder would be collected and analyzed to verify that contaminants are immobilized
and that acceptable transport rates had been achieved. A limited clay cap may be placed
over the area to limit infiltration of water into the stabilized soil.
Because contaminants are left in the soil and the soil matrix is disturbed with this
alternative, institutional controls would be required after solidification to ensure that
contaminants are not transported to ground water. Land use restrictions would be
implemented to prohibit subsurface development in the vicinity of the treated area.
The capital cost for this alternative is $1,887,000. The annual operating cost of
Alternative 5 would be $36,600 for years 1 through 10 and $30,900 for years 11 through
30. The total 30-year present worth cost for Alternative 5 is $2,247,000.
5.3 COMPARATIVE ANALYSIS OF ALTERNATIVES
The five alternatives were compared to assess the relative advantages and disadvantages
of each and to identify key tradeoffs that were balanced in selecting an alternative for soil
cleanup. The preferred alternative was developed based upon the following comparisons,
considering the expected results of the combination of alternatives from each set.
5.3.1. Evaluation Criteria
The alternatives were compared with respect to nine evaluation criteria that have been
developed under CERCLA to address the technical and policy considerations associated
with selecting among the remedial alternatives. The nine evaluation criteria are
described below.
Threshold Criteria
Threshold criteria include overall protection of human health and the environment and
compliance with Applicable or Relevant and Appropriate Requirements (ARARs). These
threshold criteria must be met by any given alternative before it can be evaluated under
the five balancing criteria.
1. Overall Protection of Human Health and the Environment describes whether
the alternative as a whole achieves and maintains adequate protection of human
health and the environment.
2. Compliance with ARARs describes whether the alternative complies with
ARARs or, if a waiver is required, how it is justified. Other information from
advisories, criteria, and the guidance "to be considered" is also addressed.
Balancing Criteria
The five balancing criteria form the basis of the comparative analysis because they allow
tradeoffs among the alternatives offering different degrees of performance.
5-8
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3. Long-Term Effectiveness and Permanence refers to the ability of an alternative
to provide reliable protection of human health and the environment over the long
term.
4. Reduction of Mobility, Toxicity, and Volume Through Treatment refers to the
preference for treatment technologies that meet this criteria.
5. Short-Term Effectiveness examines the effectiveness of alternatives in
protecting human health and the environment during the construction and
implementation of a remedy and until the response objectives have been met. The
length of time to achieve remedial action objectives also is a part, of short-term
effectiveness.
6. Implementability evaluates the technical and administrative feasibility of the
alternatives and the availability of the goods and services needed to implement
them.
7. Cost refers to the capital, indirect, and operation and maintenance costs of each
alternative. Costs are estimated and expected to provide an accuracy of plus 50
percent to minus 30 percent for a 30-year period. The 30-year period is used as a
common point of comparison. Cost can only be a deciding factor for alternatives
equally protective of human health and the environment.
Modifying Criteria
The modifying criteria described below generally are addressed in response to comments
from the State and the public, after the issuance of the Proposed Plan.
8. State Acceptance indicates whether the State agrees with, opposes, or has no
comment on the preferred alternative.
9. Community Acceptance indicates whether the community agrees with, opposes,
or has no comment on the preferred alternative.
5.3.2. Comparative Analysis
In this section, the alternatives are compared to evaluate their relative performances
according to each of the evaluating criteria. The objective of the comparison is to assess
the relative advantages arid disadvantages of the alternatives and to identify the key
tradeoffs that must be balanced in selecting a preferred alternative. A comparison
between alternatives for each criterion is discussed briefly in the following paragraphs.
Protection of Human Health and the Environment. Every alternative except the no
action alternative provides long-term protection of human health and the environment.
Although the no action alternative currently provides protection against exposure risks,
the absence of access restrictions or warning signs may allow future accidental exposure
5-9
-------
to contaminants. Institutional controls are protective because leaving the building in
place and maintaining the slab will act as an extensive barrier over the contaminated soil
without having to construct anything or disturb the soil. The institutional controls restrict
access, require potentially exposed workers to use personal protective equipment, and
provide administrative controls for future changes. Alternative 2 and the three treatment
alternatives (3, 4 and 5) all are protective because all exposure pathways are addressed.
The in-situ solidification (Alternative 5) is additionally protective because it limits health
risks to construction workers during remediation.
Compliance with ARARs. All alternatives, except Alternative 1 would comply with
ARARs. ARARs for storage and treatment of contaminated soil are necessary for
Alternatives 3, 4, and 5. Alternatives 3,4, and 5 must also meet air quality requirements
for VOC emissions and dust emissions.
Table 5-3 lists the key ARARs with which each alternative must comply and how
compliance would be achieved. This table also indicates whether the ARARs are
applicable or relevant and appropriate, and whether they are location, action, or chemical
specific.
Long-Term Effectiveness and Permanence. Because the chemicals detected at OU 7
are primarily metals, the alternatives (except no action) all are effective at isolating the
metals from further transport. The excavation and soil washing alternatives (Alternatives
3 and 4) are very effective in the long term because they remove the metals from the soil,
dispose of them in proper disposal facilities, and do not limit future development at the
site. In-situ solidification (Alternative 5) also is effective but is rated below the
excavation alternatives. This alternative stabilizes the metals to prevent further transport,
but because the contaminants will remain on-site, it is possible that the solidification
agent could break down with time. The institutional controls alternative is rated below
the treatment and excavation alternatives because management controls must be used to
maintain the effectiveness of the cover, and because contaminants remain in the soil.
However, as long as the institutional controls are in place, this alternative is a permanent
solution.
Reduction of Toxicity, Mobility, and Volume. Reduction of toxicity, mobility, and
volume (TMV) refers to reduction of TMV through treatment at the site. The. soil
washing alternative (Alternative 4) has the highest rating as this alternative removes
COCs from soil by on-site treatment, with a large reduction in toxicity. The excavation
and off-site disposal alternative (Alternative 3) and soil solidification (Alternative 5) rate
the next highest due to their reduction in contaminant mobility. Alternative 2 reduces
mobility for the long term, but does not utilize treatment. Alternative 1 is similar to
Alternative 2, but without the long-term controls.
Short-Term Effectiveness. The no action and institutional controls alternatives
(Alternatives 1 and 2) rated the highest for this criterion because, with no construction,
there are no risks to on-site workers. In-situ treatment (Alternative 5) rates lower than no
action and institutional controls because some COCs on dust particles would be generated
during the treatment. Proper shrouding, ventilation, and personal protective equipment
5-10
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TABLE 5-3
SUMMARY OF KEY ARARs FOR EACH ALTERNATIVE
Alternative
Key ARARs With Which the Alternatives Must Comply (a) ARAR Type
Would Alternative Meet ARAR?
Alternative 1
(No Action)
Alternative 2
(Insiiiulional Controls)
Alternative 3
(Excavation and Off-Site
Disposal)
R3II-2II UAC
(Slate of Utah corrective action standards for CF.RCLA and UST
sites)
R315-8-6 UAC
(Slate of Utah ground-water protection rule)
R315-8-7 UAC
(Closure and post closure standards)
R3I5-IOI UAC
(Slate of Utah cleanup action and risk-bated closure standards)
R3 17-6 UAC
(Slate of Ulah ground-water quality protection standards)
40 CFR Part 264. Subparl F
(Requirements for detection and containment of releases)
40 CKR Part 264. Subpart G
(Closure and post closure standards)
R.1II-2II UAC
(Stale of Ulah rnrrccti\e action slaml.trds for CKRCLA and UST
sites)
R315-8-6 UAC
(Stale of Ulah ground waii-r protection rule)
R.I 15 8-7 UAC
(Closure ami post cliwurr standards)
R315-101 UAC
(Stale of Ulah cleanup action and risk-based closure standards)
R.I 17-6 UAC
(State of Utah ground-waler quality protection standards)
40 CFR Part 264. Subparl F
(Requirements Tor detection and containment of releases)
40 CFR Part 264, Subpart G
(Closure and post closure standards)
R307-I-3UAR
(Emission standards for control of installations)
R307-I-4UAC
(Establishes emission standards)
R307-IOUAC
(NESHAPs Standards)
R3II-2IIUAC
(Slate of Utah corrective action standards for CERCLA and UST
sites)
R315-8-6 UAC
(State of Ulah ground-water protection rule)
R315-8-7 UAC
(Closure and post-closure standards)
R3I5-IOI UAC
(State of Ulah cleanup action and risk-based closure standards)
R3I7-6UAC
(State of Utah ground-water quality protection standards)
Ap A, C No - Meets this ARAR with environmental monitoring, but does not meet the ARAR due to lack of
source control.
Ap A Yes - Complies with this ARAR by providing ground-waler monitoring.
R A No - Does not comply with this ARAR because no provisions ore made to control and minimize
access to hazardous constituents.
Ap A. C No - Partially meets ARAR with environmental monitoring, but does not meet closure
requirements.
Ap A. C No - Does not meet this ARAR because it does not maintain the concrete slab or prevent leachate
from reaching ground water.
R A Yes - Complies with this ARAR by providing ground-water monitoring.
R A No - This alternative does not make provisions for landfill closure regulations.
Ap A. C Yes - Meets this ARAR with environmental monitoring and source control (leaving and maintaining
the concrete slab).
Ap A Yes - Complies with this ARAR by providing ground-water monitoring.
R A Yes -Complies with relevant and appropriate portions of hybrid landfill closure regulations. The
soil cover requirement is relevant, but not appropriate in this case.
Ap A. C Yes - Meets this ARAR with environmental monitoring, source control (leaving and maintaining
the concrete slab), and post-closure requirements.
Ap A, C Yes - Complies with ground-water quality protection standards because it prevents leachate from
reaching ground water by leaving and maintaining the concrete slab.
R A Yes - Complies with this ARAR by providing ground-water monitoring.
R A Yes-Complies with relevant and appropriate portions of hybrid landfill closure regulations. The
soil cover requirement is relevant, but not appropriate in this cose.
Ap A. C Yes - Air emissions during remediation will be controlled to comply with air emissions
requirements.
Ap A. C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
Ap A, C Yes - Meets this ARAR with environmental monitoring and source removal.
Ap A Yes - Complies with this ARAR by providing ground-water monitoring.
R A Yes - Complies with clean closure.
Ap A, C Yes - Meets this ARAR with environmental monitoring, source removal, and post-closure
requirements. '
Ap A, C Yes - Complies with ground-water quality protection standards because it removes the
contaminated soil in the source area.
-------
TABLE 5-3
SUMMARY OF KEY ARARs FOR EACH ALTERNATIVE
(CONTINUED)
Alternative
Key ARARs With Which the Alternatives Must Comply (8) ARAR Type
Would Alternative Meet ARAR?
Alternative 3 (ron't)
(Excavation and
Off-Site Disposal)
Alternatjve 4
(Excavation, On-Sile. Soil
Washing, and Backfill)
V
40 CFR 50 (Primary and secondary air quality standards)
40CFR6I (NESHAPs standards)
40 CFR Part 264, Subparl F
(Requirements Tor detection and containment of releases)
40 CFR Part 264, Subparl G
(Closure and post closure standards)
R307-I-3UAR
(Emission standards Tor control or installation!:)
R307-I-4UAC
(Establishes emission standards)
R307-IOUAC
(NKSHAPs standards)
R3II.-2IIUAC
(Slate of Ulan corrective action standards for CKRCLA and UST
sites)
R.I 15 8-6 U AC
(Slate of Utah ground-water protection rule)
R.I 15 8-7 UAC
(Slate of Utah closure and post-closure standards)
R3I5-8-I6UAC
(Design and operation requirements for miscellaneous units)
R315-8-21 UAC
(Corrective action management units and temporary units)
R315-13 UAC
(State of Utah land disposal restrictions)
R3I5-IOIUAC
(State of Utah cleanup action and risk-based closure standards)
R317-6 UAC
(State of Utah ground-water quality protection standards)
R317-8 UAC
(Stale of Utah pollutant discharge elimination systems)
40 CFR SO (Primary and secondary air quality standards)
40 CFR 61 (NESHAPs standards)
40 CFR Part 264 Subpart B, 264.18
(Characteristics for location of hazardous waste management units)
40 CFR Part 264 Subpart F
(Requirements for detection and containment of releases)
40 CFR Part 264 Subpart G
(Closure and post closure standards)
40 CFR Part 264 Subpart X
(Design and operational requirements for miscellaneous units)
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirement!!.
R A Yes - Complies by monitoring ground water.
R A Yes - Complies with clean closure.
Ap A, C Yes - Air emissions during remediation will be controlled to comply with air emissions
requirements.
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
Ap A, C Yes - Meets this ARAR with environmental monitoring and source control.
Ap A Yes - Complies with this ARAR by providing ground-water monitoring.
Ap A Yes - Complies with clean closure.
Ap A Yes - Any on-sile treatment will be designed and operated in accordance with this requirement.
Ap A Yes - All remedial technology units will be managed in accordance with this ARAR.
Ap A, C Yes - All residual sludge generated during soil washing will be required to meet BOAT
technologies and/or constituent concentrations.
Ap A, C Yes - Meets this ARAR with environmental monitoring, source control, and post-closure
requirements.
Ap A. C Yes - Complies with ground-water quality protection standards because it controls the source area
by reducing the toxicity of the contaminants.
Ap A Yes - Complies by discharging all waste fluids to the IWTP (a permitted facility).
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
Ap C Yes - Air emissions during excavation would be controlled to comply with air emissions
requirements.
A Yes - Soil washing units will be sited in accordance with this ARAR.
Ap
Ap
Ap
Ap
A Yes - Complies by monitoring ground water.
A Yes - Complies with clean closure.
A Yes - Any on-site treatment will be designed and operated in accordance with this requirement.
-------
TABLE 5-3
SUMMARY OF KKY ARARs FOR EACH ALTERNATIVE
(CONTINUED)
Alternative
Key ARARs With Which the Alternatives Must Comply (a)
ARAR Type
Would Alternative Meet ARAR?
Alternative 4 (con'l)
(Excavation. On-Sile. Soil
Washing, and Backfill)
Alternative 5
(In-Silu Solidification)
40 CrU Part 268 Ap
(Land disposal restrictions)
40 CFR Part 40.1 Ap
(Standards to control discharge through POTWs)
R307-I-3UAR Ap
(Emission standards Tor control of installations)
R307-I-4UAC Ap
(Establishes emission standards)
R307-IOUAC Ap
(NESHAPs standards)
R3II-2IIUAC Ap
(Stale nf Utah corrective action standards for CKRCLA and UST
sites)
R.I 15-8-6 UAC Ap
(Slate of Utah pround-wairr protection rule)
R.I 15 8-7 LI AC R
(Closure and post closure standards)
R.I 15-101 UAC Ap
(Stale of Iliah cleanup action and risk-hased closure standards)
R.I 17-6 U AC Ap
(Slate of Utah ground water quality protection standards)
40 O-'R SO (Primary and secondary air quality standards) Ap
40 CFR 61 (NESHAPs standards) Ap
40 CFR Part 264 Suhpart F R
(Requirements Tor detection and containment of releases)
40 CFR Part 264 Subpart G R
(Closure and post closure standards)
40 CFR Part 264 Subpart X Ap
(Design and operational requirements for miscellaneous units)
A. C Yes - All residual sludge generated during soil washing will be managed according to this
requirement.
A Yes - Discharge from soil washing alternative will comply with this ARAR.
A. C Yes - Air emissions during remediation will be controlled to comply with air emissions
requirements.
A, C Yes - Complies with this ARAR by collecting all emissions and discharging them through a vapor
phase activated carbon canister.
C Yes - Air emissions during solidification would be controlled to comply with air emissions
requirements.
A. C Yes - Meets this ARAR with environmental monitoring and source control (immobilization of
contaminants).
A Yes - Complies with this ARAR by providing ground-water monitoring.
A Yes - Complies wilh landfill closure.
A. C Yes - Meets this ARAR wilh environmental monitoring, source control (immobilization of
contaminants), and post-closure requirements.
A, C Yes - Complies wilh ground-water quality protection standards because it controls the source area
by immobilizing the contaminants using solidification.
C Yes - Air emissions during solidification would be controlled to comply with air emissions
requirements.
C Yes - Air emissions during solidification would be controlled to comply with air emissions
requirements.
A Yes - Complies with this ARAR by providing for ground-water monitoring.
A Yes - Complies wilh landfill closure.
A Yes - Any on-site treatment will be designed and operated in accordance with this requirement.
ARAR Applicable or relevant and appropriate requirement BDAT
RCRA Resource Conservation and Recovery Act UAC
Ap Applicable R
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act UST
(a) A more complete list of the ARARs pertaining to OU 7 appears in Appendix A.
Best demonstrated available technology A
Utah Administrative Code C
Relevant and Appropriate L
Underground Storage Tank POTW
Action-Specific ARAR
Chemical-Specific ARAR
Location-Specific ARAR
Publicly-Owned Treatment Works
-------
for on-site workers could effectively mitigate any adverse impacts. Excavation/soil
washing and disposal (Alternative 4) and excavation and off-site disposal (Alternative 3)
rate lower than in-situ treatment because excavation of the area of attainment could
generate greater amounts of dust. Potential health effects from contaminated dust on
workers could be mitigated by restricting excavation on windy days, covering excavated
soils, and requiring dust-protective personal protective equipment.
Implementability. All the remedial alternatives are considered implementable. No
action (Alternative 1) and institutional controls (Alternative 2) are most easily
implemented technically and administratively.
In-situ treatment (Alternative 5) rates lower because, although it is technically feasible,
there would be administrative difficulties. Implementation of this alternative would
require demolition of much of the eastern portion of Building 225 to allow access to the
area of attainment. Because Hill AFB and the U.S. Air Force rely on the maintenance
operation in Building 225, implementation of this remedy would disrupt Air Force
operations.
Excavation and off-site disposal and excavation, soil washing, and disposal
(Alternatives 3 and 4) rate below in-situ treatment. These alternatives, while technically
feasible, would have the same impacts on Air Force operations as in-situ treatment. In
addition, because contaminants would be transported off-site, land disposal restrictions
(LDRs) may require treatment of wastes prior to disposal.
Costs. The no action followed by institutional controls alternatives have the lowest
overall costs ($460,000 and $627,000 respectively). In-situ solidification has the next
lowest cost ($2,247,000), followed by excavation/soil washing/disposal ($5,221,000).
The excavation and off-site disposal alternative has the highest cost ($7,332,000).
State and Community Acceptance. The State of Utah agrees with the preferred
alternative. Although a member of the community raised minor concerns at the public
meeting, these concerns were addressed and resulted in no change to the preferred
alternative (see Part One of the Responsiveness Summary). On this basis, the preferred
alternative is acceptable to the State and community and is thereby selected for
implementation at OU 7.
5-14
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6.0 SELECTED REMEDY
6.1 DESCRIPTION OF THE SELECTED REMEDY
The selected remedy at Hill AFB Operable Unit 7 is Alternative 2-Institutional Controls.
Alternative 2 consists of limiting access to the area of attainment beneath Building 225
by having the Base Commander issue a continuing order, posting warning signs, and
providing for restrictions on future land use in the deed for Hill AFB. Also, because
contaminants above risk-based levels will remain on site, long-term environmental
monitoring and five-year site review are required.
Continuing Order. The continuing order will restrict access to or disturbance of
contaminated soils as long as Hill AFB owns the property. Specifically it will:
Restrict the installation of any new underground utilities or other construction
activities beneath the floor in the area of attainment, thus preventing
accidental exposures to the construction worker.
Provide for the use of proper protective equipment if, for any reason, the
concrete floor slab in the former Metal Plating Shop Area is to be removed.
Require that the integrity of the concrete floor slab be maintained (i.e., repair
cracks that may develop) so that fluids cannot infiltrate to the subsurface.
Maintenance of the floor slab will require development of SOPs to provide for
inspections, floor repairs, and responses to spills in critical areas.
Warning Signs. Warning signs would be posted around the area of attainment stating
that hazardous chemicals are present beneath the floor slab, and that no excavation is
permitted without proper authorization.
Deed Restrictions. A notice to the deed would be filed by the Air Force in the real
property records of Davis County incorporating the restrictions in the continuing order.
In the case of the sale or transfer of property within OU 7 by the United States to any
other person or entity, the Air Force will place covenants in the deed that will restrict
access and prohibit disturbance of contaminated soils or the remedial action without
approval of the United States. These covenants will be in effect until removed upon
agreement of the State of Utah, the U.S. Environmental Protection Agency, and the U.S.
Air Force or their successors in interests. The Air Force also will include in the deed the
covenants required by section 120(h)(3) of the Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA). which include (1) a warranty that the United
States will conduct any remedial action found to be necessary after the date of the
transfer; (2) a right of access in behalf of the U.S. Environmental Protection Agency and
the Air Force or their successors in interest to the property to participate in any response
or corrective action that might be required after the date of transfer. The right of access
referenced in the preceding sentence shall include the State of Utah for purposes of
conducting or participating in any response iOr corrective action that might be required
after the date of transfer.
6-1
-------
Long-term environmental monitoring will include ground-water sampling and soil
moisture measurements so that the potential for contaminant transport can be monitored.
Building 225 and the surrounding pavement currently act as a barrier over the
contaminated soil, limiting infiltration and preventing exposure to the soils. If the current
land use changes or structures over the area of attainment are removed, the Air Force will
conduct an immediate site review and re-evaluate the protectiveness of the remedy
selected for OU 7. Also, the Air Force will take any appropriate remedial action.
Figure 6-1 shows a conceptual schedule for the order of implementation of the
components of the selected remedy. The actual schedule will be negotiated according to
the terms of the Federal Facility Agreement (FFA) for Hill AFB. The first activities will
include issuance of the continuing order and installation of the ground-water and soil
moisture monitoring network. The continuing order will limit access to contaminated soil
and the ground-water and soil moisture monitoring network will monitor the potential for
contaminant movement in the saturated and unsaturated zones beneath the former Metal
Plating Shop Area. Ground-water and soil moisture monitoring are scheduled on a semi-
annual basis and will continue as long as the remedy is in place. Following the initial
activities, Hill AFB will file a notice to the deed for its on-Base property and post
warning signs in the former Metal Plating Shop area.
6.1.1. Remediation Goals and Performance Standards
The goals of this remedial action are described in the following section. The performance
of this alternative with respect to meeting the remediation goals will be monitored
according to the Performance Monitoring Plan to be developed during implementation of
the institutional controls.
As stated in Section 5.1, the remedial action objectives (goals) for OU 7 are to:
Reduce contaminant transport within source areas and reduce chemical
transport from soil to ground water by minimizing surface water infiltration.
Prevent human exposure to contaminated soil through ingestion, inhalation,
and dermal contact, such that the additional risk to an individual for cancer is
below 1 x 10~6 and the non-cancer threshold is less than 1.0.
Reduce contaminant concentrations to meet risk levels and/or reduce
contaminant transport to rates that will not impact ground-water quality above
Maximum Contaminant Levels.
Chemical-specific cleanup goals were developed for alternatives that involve treatment
and/or excavation. These goals were based on chemical partitioning models to prevent
ground-water contamination above maximum contaminant levels or correspond to a
1 x 10'6 (one in a million) additional cancer risk. Although the selected remedy will not
meet these chemical-specific goals, implementation of institutional controls will meet
each of the remediation goals. Maintaining the floor above the areas of attainment will
6-2
-------
PROJECT NO. 2208.0875
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NOTES: "Time zero' Is defined as the beginning of substantial, continuous physical Improvement.
which will begin IS months after this ROD Is signed.
Schedule Is schematic and does not Include remedial design. Actual schedule will be
negotiated under the Federal Facility agreement for Hill AFB.
Hill AFB OU 7 ROD
HILL AIR FORCE BASE
OPERABLE UNIT 7
CONCEPTUAL REMEDIAL ACTION
IMPLEMENTATION SCHEDULE
FIGURE 6-1
-------
reduce contaminant transport within the area of attainment and movement from soil to
ground water by eliminating surface water infiltration. Keeping the floor intact and
restricting excavations will prevent human exposures to contaminated soil, both for
current exposure scenarios (through signs and a continuing order) and for future scenarios
(through restrictions to the deed for Hill AFB). Finally, by reducing the contaminant
transport rates, ground-water quality will not be impacted above Maximum Contaminant
Levels.
To evaluate whether water that could initiate chemical transport is moving into the area
of attainment, or whether contaminants have moved into the ground water, a performance
and compliance sampling program (PCSP) will be implemented during the remedial
action to monitor performance and compliance with remediation goals. This program
will be developed during the implementation of the selected remedy and will include
locations of soil moisture and ground-water monitoring points, monitoring frequency,
analytical parameters for ground-water samples, sampling and analytical methods, and
statistical methods for evaluating data. The PCSP will be designed to provide
information to evaluate the effectiveness of the remedial action with respect to levels of
contamination in ground water and the potential for contaminant transport, and provide
for site evaluations. The PCSP may be modified during the remedial action to take into
consideration changing site conditions.
6.1.2. Restoration Time Frame
Institutional controls for long-term management will be in place within approximately
one year of commencement of the remedial action. The restoration time frame for the
preferred alternative will extend indefinitely. For as long as the floor remains intact over
the areas of attainment, unacceptable exposure and chemical transport are controlled.
However, because there is no reduction in toxicity, mobility, or volume, restoration is
not expected in any foreseeable time frame. This alternative cannot rely on natural
attenuation as means to remediate this site because the contaminants (cadmium and
hexavalent chromium) that .are in the soil beneath the former Metal Plating Shop are
persistent and are not expected to attenuate to any great extent.
6.1.3. Costs
The estimated costs for remediating OU 7 using the selected remedy are as follows. The
total capital cost of the project is estimated at $285,000. The total capital cost includes:
installation of the ground-water and soil moisture monitoring network, administrative and
legal cost of initiating the institutional controls, filing a notice to the deed for Hill AFB,
and posting warning signs in the contaminated areas of Building 225. The indirect capital
cost for the project is estimated at S34.300. Indirect capital costs are included in the
estimated total capital costs above, and include engineering, contingency, and contract
administration.
Operation and maintenance (O&M) costs change over the duration of the remedial action.
Operation and maintenance costs are calculated for a 30-year period and do not reflect
costs that may be incurred if the remediation period lasts longer than 30 years. Annual
O&M is estimated at $165,000 for years 1 through 5, $102,000 for years 6 through 10,
and $281,000 for years 11 through 29. An additional $25,000 will be required for O&M
6-3
-------
every fifth year for the five-year site reviews, and $3,000 will be required every tenth
year for well rehabilitation. O&M costs include monitoring program costs as well as
maintenance of equipment and the concrete floor. The total present worth cost of the
selected remedy over a 30-year period, using an interest rate of ten percent, was estimated
at $729,000. The costs discussed here are estimated with +50/-30 percent accuracy for a
30-year period. During the implementation process for the selected alternative, some
changes could occur as a result of the remedial design process. These changes reflect
modifications resulting from the engineering design process and could result in changes
to the estimated costs for this alternative.
6.2 STATUTORY DETERMINATIONS
The selected remedy for Hill AFB OU 7 meets the statutory requirements of Section 121
of CERCLA as amended by SARA. These statutory requirements include protection of
human health and the environment, compliance with ARARs, cost effectiveness,
utilization of permanent solutions and alternative treatment technologies to the maximum
extent practicable, and preference for treatment as a principal element. The manner in
which the selected remedy for OU 7 meets each of the requirements is presented in the
following discussion.
6.2.1. Protection of Human Health and the Environment
The selected remedy for OU 7 protects human health and the environment by restricting
direct contact with contaminants through issuing a continuing order, posting warning
signs, and filing a notice to the deed to Hill AFB. The continuing order from the Base
Commander will include maintaining the concrete slab, restricting concrete cutting, and
limiting excavations unless proper protective equipment is used. Upon transfer of the
property, the Air Force would provide a deed covenant notifying the transferee of the
locations and the restrictions on use of the contaminated areas. As part of this alternative,
a provision will be made to re-evaluate the effectiveness of this alternative every five
years and again at the time the building and slab are removed.
6.2.2. Compliance with Applicable or Relevant and Appropriate Requirements
Section 121(d)(l) of CERCLA, as amended by SARA, requires that the remedial actions
at OU 7 must attain a degree of cleanup that assures protection of human health and the
environment. In addition, remedial actions that leave any hazardous substances,
pollutants, or contaminants on the site must, upon completion, meet a level or standard
that at least attains legally applicable or relevant and appropriate standards, requirements,
limitations, or criteria that are applicable or relevant and appropriate requirements
(ARARs) under the circumstances of the release. ARARs include Federal standards,
requirements, criteria, and limitations and any promulgated standards, requirements,
criteria, or limitations under the State of Utah environmental or facility siting regulations
that are more stringent than Federal standards. In addition, State of Utah ARARs include
all promulgated standards and rules associated with delegated State environmental
programs.
6-4
-------
"Applicable" requirements are those cleanup standards, standards of control, and other
substantive environmental protection requirements, criteria, or limitations promulgated
under Federal or State law that specifically address the hazardous substances, pollutants,
or contaminants, remedial actions, locations, or other circumstances at the OU 7 site.
"Relevant and appropriate" requirements are cleanup standards, standards of control, and
other substantive environmental protection requirements, criteria, or limitations
promulgated under Federal or State law that, while not "applicable" to the hazardous
substance, pollutant or contaminant, remedial actions, locations, or other circumstances at
a remedial action site, address problems or situations sufficiently similar to those
encountered at the site that their use is well suited to the particular site.
In evaluating which requirements are applicable or relevant and appropriate, the criteria
differ depending on whether the type of requirement is chemical-specific, location-
specific, or action-specific. According to the NCP, chemical-specific ARARs usually are
health or risk-based numerical values that establish the acceptable amount or
concentration of a chemical that may remain in, or be discharged to, the ambient
environment. Location-specific ARARs generally are restrictions placed upon the
hazardous substances or activities solely because they are in special locations. Some
examples of special locations include floodplains, wetlands, historic places, and sensitive
ecosystems or habitats. Action-specific ARARs usually are technology or activity-based
requirements or limitations on actions taken with respect to hazardous wastes, or
requirements to conduct certain actions to address particular circumstances at the site.
Utah Groundwater Quality Protection Standards and the Federal Safe Drinking Water Act
Maximum Contaminant Levels (MCLs) were used as a basis for calculating soil
contaminant levels that are protective of ground water beneath the OU 7 area. Ground-
water protection standards and MCLs also will be used to evaluate ground-water
monitoring results. Chemical-specific relevant and appropriate standards for OU 7
include portions of the Solid Waste Disposal Act and the Utah Solid and Hazardous
Waste Act. Federal and State chemical-specific ARARs are presented in Appendix A,
Tables A-l and A-2, respectively.
Federal and State location-specific ARARs are not applicable or relevant to.the OU 7
selected remedy.
Action-specific ARARs that pertain to the selected remedy at OU 7 include: the State of
Utah standards for drilling and abandoning wells, Corrective Action Cleanup Policy for
UST and CERCLA Sites, Cleanup and Risk-Based Closure Standards, and air
conservation regulations. Federal and State action-specific ARARs are identified in
Appendix A, Tables A-3 and A-4, respectively.
Table 6-1 summarizes the ARARs for the selected remedy for OU 7. The remedy
selected for OU 7 will meet ARARs. However, because contaminants are left in place
the remedial action time frame likely will exceed 30 years. As long as the institutional
controls are in place, this selected remedy will be a permanent solution that will be
protective of human health and the environment.
6-5
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TABLE 6-1
SUMMARY OF ARARs FOR THE SELECTED REMEDY
Alternative
ARARs With Which the Selected Remedy Must Comply
Alternative 2 (Institutional Controls)
ON
R311-211 UAC
(State of Utah corrective action standards for CERCLA and UST sites)
R315-8-6 UAC
(State of Utah ground water protection rule)
R315-8-7 UAC
(Closure and post closure standards)
R315-IOI UAC
(State of Utah corrective action standards for RCRA sites)
R317-6 UAC
(State of Utah ground-water quality protection standards)
R655-4 UAC
(Standards for drilling and abandonment of wells)
40 CFR Part 264, Subpart F
(Requirements for detection and containment of releases)
40 CFR Part 264, Subpart G
(Closure and post closure standards)
ARAR Applicable or relevant and appropriate requirement
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
RCRA Resource Conservation and Recovery Act
UAC Utah Administrative Code
UST Underground Storage Tank
-------
A decision to invoke any changes to this selected remedy may be made during a periodic
review of the remedial action, which will occur at least every five years in accordance
with CERCLA Section 121(c).
6.23. Cost Effectiveness
Overall cost effectiveness can be defined as the reduction of the threat to human health
and the environment per dollar expended on a remedy. The selected remedy for OU 7
was chosen to provide the necessary protection to human health and the environment.
When two alternatives had an equal measure of protection, the alternative with the lower
cost was selected. An example of this is solidification of contaminants versus
institutional controls. Both of these remedies would provide protection by limiting access
to contaminated soils and potential for contaminant transport to ground water. However,
the solidification alternative would cost approximately three times more than the selected
remedy not including the cost of tearing down the building to gain access to the
contaminated soils and relocating the current work missions in Building 225. When this
is taken into consideration the cost of Alternative 5 would possibly be more than 20 times
that of the selected remedy.
6.2.4. Utilization of Permanent Solutions
The selected remedy provides the best balance of tradeoffs among all the alternatives
with respect to the five summary balancing criteria which include:
Long-term effectiveness and permanence
Reduction of toxicity, mobility, or volume through treatment
. Short-term effectiveness
Implementability
Cost.
The criterion that was critical in the selection decision was implementability. While all
the alternatives are technically feasible and the needed goods and services are available,
removing part of Building 225 to implement the treatment and/or excavation alternatives
would have a large impact on the Air Force's operations at Hill AFB. Only no action or
the selected alternative could be implemented without demolishing a portion of Building
225. The modifying criteria, which are State and community acceptance have had no
effect on selection of the remedy since the State agrees with the alternative selected, and
the community concerns related to the proposed alternative have been addressed. The
selected remedy meets the statutory requirement to utilize permanent solutions to the
maximum extent practicable.
6-7
-------
6.2.5. Preference for Permanent Solutions and Treatment Technologies or Resource
Recovery Technologies to the Maximum Extent Practicable
The selected remedy for OU 7 utilizes permanent solutions and treatment technologies to
the maximum extent practicable. The institutional controls alternative was the most
practicable alternative for OU 7. The selected remedy is expected to permanently contain
and isolate the contaminants. The potential future risks are exposure to contaminated soil
for construction workers and future residents. Because of the current industrial use of
this part of the Base it is highly unlikely that this area will be used for residential
neighborhoods. To ensure the effectiveness of the selected treatment remedy, Hill AFB
will conduct a review within five years after initiating the selected remedy and the
remedy will be reevaluated if there is a change in land use for Building 225.
6.3 DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for Hill AFB OU 7 was released for public comment in February
1995. The Proposed Plan identified Alternative 2-Institutional Controls as the preferred
alternative. This remedy includes: issuing a continuing order by the Base Commander,
filing a notice to the deed for Hill AFB, posting warning signs, and ground-water and soil
moisture monitoring. All written and verbal comments received during the public
comment period were reviewed, and it was determined that no significant changes were
necessary to the remedy identified in the Proposed Plan. A copy of the proceedings of
the Proposed Plan public meeting as well as the comments received are included as
Appendices B and C, respectively.
6-8
-------
Hill Air Force Base, Utah
Operable Unit 7
Responsiveness Summary
-------
Overview
This responsiveness summary provides information about the views of the community
with regard to the proposed remedial action for Hill Air Force Base (AFB) Operable
Unit 7 (OU 7), documents how public comments have been considered during the
decisionmaking process, and provides responses to concerns.
The public was informed of the preferred alternative in the following ways:
All items contained within the Administrative Record have been on file at the
subject repositories since the final version of each document was issued
A copy of the Proposed Plan was sent to all affected and interested parties
prior to the public comment period
A public comment period was held from February 20, 1995, through
March 21, 1995
A public meeting was held on March 1, 1995, at the Base Theater,
Building 441, Hill AFB, Utah
Written comments by the public were encouraged.
The public meeting was poorly attended and residents voiced few concerns about the
nature and extent of contamination. A transcript of the public meeting is attached as
Appendix B. No comments were made that affect the proposed remedial action for OU 7.
No written comments were received during the public comment period.
Background on Community Involvement
The public participation requirements of CERCLA Sections 113(k)(2)(B)(i-v) and 117
were met. Hill AFB has a Community Relations Plan that was finalized in January 1993.
The community relations activities include: (1) a Remedial Advisory Board (RAB),
which meets at least quarterly and includes community representatives from adjacent
counties and towns, (2) a mailing list for interested parties in the community, (3) a bi-
monthly newsletter called "EnviroNews," (4) visits to nearby schools to discuss
environmental issues, (5) community involvement in a noise abatement program, (6)
semi-annual town council meetings, (7) opportunities for public comment on remedial
actions, and (8) support for the community in obtaining technical assistance grants
(TAGs).
The Remedial Investigation/Feasibility Study (RI/FS) Report for OU 7 (Montgomery
Watson, 1995), and the Proposed Plan for Operable Unit 7 (Montgomery Watson, 1995a)
were released to the public, and are available in the Administrative Record maintained at
the Davis County Library and at the Environmental Management Directorate at Hill AFB.
The notices of availability for these documents were published in the Salt Lake Tribune.
A public comment period was held from February 20, 1995 through March 21, 1995. In
-1-
-------
addition, a public meeting was held on March 1, 1995. At this meeting, representatives
from Hill AFB, EPA, and the State of Utah answered questions about the site and the
selected remedy. A court reporter prepared a transcript of the meeting. Copies of the
transcript and all written public comments received during the comment period have been
placed in the Administrative Record. In addition, copies of the transcript were sent to all
meeting attendees who requested them. Responses to the comments received during the
public comment period are included in this Responsiveness Summary, which is pan of
the ROD. The decision process for this site is based on the Administrative Record.
Summary of Public Comments and Agency Responses
Part I - Summary and Response to Local Community Concerns. The community
comments and concerns are discussed in the following section.
Expected Lifetime of Building 225. A member of the community was interested in
knowing how long the Air Force was planning to keep Building 225 as an operating
facility because this is a measure of how long the institutional controls would be in effect.
In response to this comment, an Air Force representative stated that there is every
indication that the building will stay in operation for the foreseeable future. Any exact
time frame of how long the building will be in operation is impossible to estimate.
Ground-Water and Soil Moisture Monitoring System. Several questions were
directed towards the ground-water and soil moisture monitoring system by a member of
the community. These questions included;
(1) How many monitoring points are currently in the ground?
(2) Are the monitoring wells sufficient to indicate the potential for contaminant
migration?
(3) Are you looking at one monitoring point?
(4) Is there going to be monitoring around the edge of the slab?
(5) Is soil moisture monitoring adequate to show there is no further migration?
In response to the first question, the citizen was told that there is currently one monitoring
well located within the area of contamination and one upgradient well. Hill AFB will
need to install an additional well or two downgradient of the contaminated area. At this
time there are no available borings for the soil moisture monitoring systems. These
borings will need to be installed.
In response to question 2, it was indicated that using just the monitoring wells alone
could make contaminant migration difficult to detect. The response to question 3 was
also a continuation of the response to question 2. In this response it was stated that
upgradient and downgradient wells are used. There are also other monitoring wells in the
area that receive standard monitoring. If contaminant concentrations increase in the
-2-
-------
ground water it would be an indication that contamination from the soil is entering the
ground water. However, without soil moisture monitoring it would not be certain
whether the contamination was coming from the former Metal Plating Shop source or if
there was another source that had not yet been identified. The soil moisture data will
provide a second piece of information that will determine if there has been contaminant
transport or not. For example, if there was a significant increase in soil moisture six or
seven months before the contaminant concentrations in ground water are seen to increase,
it would be likely that contaminant transport from the former Metal Plating Shop was
occurring. However, if there was a rise in ground-water contaminant concentrations and *
there is no change to the dry conditions within the plating shop area, then it would be
likely that the contaminants are coming from another source.
In response to the last question, the community member was told that while the soil is
dry, there is no potential for contaminant transport. However, if soil moisture increases
and the potential for contaminant transport increases, the selected remedy would be
revisited. In addition, the Air Force feels that with the ground-water and soil moisture
monitoring programs, they will have a good feel for contaminant transport potential.
Monitoring for Chromium. A community member asked if there was going to be
chromium monitoring as part of the selected remedy. In response, he was told that a
significant number of samples were analyzed for chromium during the investigation, and
that the results were sufficient to make decisions regarding remedial action. Additional
characterization would be done in the future, when and if the building is removed.
However, soil moisture will be monitored, and if it increases to a level where transport of
chromium may take place, then the remedial action will be re-evaluated and appropriate
action taken. This action would include collection of additional soil samples.
Costs of Treatment Alternatives. In a comment to the public, a statement was made by
a representative of the Utah Department of Environmental Quality to the effect that the
costs of Alternatives 3 through 5 do not include removal of the building for those types of
remediation. The cost would significantly increase for those alternatives if the existing
building was to be removed and a new facility built to take care of the existing Building
225 operations.
Part II - Comprehensive Response to Specific Legal and Technical Questions
No specific legal and technical questions were raised by the community.
Remaining Concerns
There are no remaining public concerns that were not addressed directly during the RI/FS
process.
-3-
-------
Hill Air Force Base, Utah
Operable Unit 7
References
-------
REFERENCES
Alloway, 1990. Heavy Metals in Soils. Halsted Press, N.Y., John Wiley and Sons, Inc.
Hem, 1985. Study and Interpretation of Chemical Characteristics of Natural Water, Third
Edition. U.S. Geological Survey Water Supply Paper 2254,263 p.
Hill AFB, 1987. Paint Chip Settling Tanks at Building 220. Hill AFB, Utah. May 1987.
Hill AFB, 1989. PCB Spill Sampling and Cleanup in Building 225, Hill AFB, Utah. Hill
AFB, Environmental Management Directorate Restoration Division, November
.1989.
Howard, 1990. Handbook of Environmental Fate and Transport Data, Volumes I through
ffl. Lewis Publishers, Chelsea, Michigan.
JMM, 1991. Final Site Characterization Report for a Portion of Building 225 and Site
Investigation of Fill Soils at Base Supply Well 6, Hill AFB, Utah. Prepared for Hill
AFB/EMR, December, 1991.
JMM, 1993. Remedial Investigation/Feasibility Study Work Plans for Operable Unit 7
(Including: Sampling and Analysis Plan; Health and Safety Plan; and Work Plan).
Prepared for U.S. Air Force Logistics Command, January 1995.
Montgomery Watson, 1995. Final RI/FS for OU 7. Prepared for U.S. Air Force Logistics
Command, February, 1995.
Montgomery Watson, 1995a. Final Proposed Plan for OU 7. Prepared for U.S. Air Force
Logistics Command, March 1995.
National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part
300.
Owen, 1994. Personal Communication with John Owen, Hill AFB Employee, to Mark
Loucks (Montgomery Watson). September 1994.
Radian, 1984. Final Treatment System or Toxic Organics Removal from Aircraft
Paint/Strip Facility Wastewaters; Prepared for Hill AFB, Utah. June 1984.
Radian, 1988. Installation Restoration Program Phase II - Confirmation/Quantification
Stage I Building 220, Paint Hangar; Prepared for Hill AFB, Utah. May 1988. .
USAF, 1989. Hill Air Force Comprehensive Plan.
USGS, 1992. Final RI Report of Operable Unit 4. Prepared for U.S. Air Force Logistics
Command. September 1992.
R-l
-------
FEDERAL AND STATE ARARs
Appendix A
-------
APPENDIX A
ARARs PERTAINING TO ACTIVITIES AT OU 7
A.0.0.1. This appendix presents the ARARs applicable or relevant and appropriate to the
five alternatives evaluated in the OU 7 Feasibility Study. The ARARs are organized into.
tables that identify them as Federal or State requirements and according to whether they
are chemical- or location-specific. The tables report the Standard, Requirement, Criterion
or Limitation applicable to the chosen remedy for OU 7, the citation, a description, and a
discussion of whether the ARAR is applicable and/or relevant and appropriate, and
comments on how the ARAR may be applied.
A.0.0.2. Tables A-1 and A-2 identify Federal and State chemical-specific ARARs for the
chosen remedy for OU 7 and Tables A-3 and A-4 identify Federal and State action-
specific ARARs for OU 7. There are no location-specific ARARs that pertain to the
alternatives evaluated for OU 7.
A-l
-------
TABLE A-l
IDENTIFICATION OF FEDERAL CHEMICAL-SPECIFIC ARARs
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/
Relevant
and
Appropriate
Comment
Solid Waste Disposal Act -42 USC งง690 1-6987 ; -
Criteria for the Identification
and Listing of Hazardous
Waste
Requirements for Releases
from Solid Waste
Management Units
Land Disposal Restrictions
40 CFR Part 261
40 CFR Part 264,
Suhpart F
40 CFR Part 268
Establishes solid wastes that are
subject to regulation as hazardous
waste under 40 CFR Parts 124, 262-
265, 268, and 270.
Establishes maximum
concentrations for hazardous
constituents in the groundwater.
Establishes maximum
concentrations for hazardous
constituents prior to land disposal.
Yes/~
No/Yes
Yes/~
Wastes generated during the remediation
phase which are determined to contain RCRA
hazardous constituents, will be subject to
these requirements.
The groundwater cleanup standards may be
based on these maximum concentrations if
they are more stringent than MCLs or non-
zero MCLGs, or if no standards exist.
Hazardous wastes generated during the
remediation phase will be subject to land
disposal restrictions and may be required to
meet BOAT technologies and/or constituent
concentrations.
Clean Air Act - 42 USC งง 7401-7642
NESHAPs Standards
National Primary and
Secondary Ambient Air
Quality Standards
40 CFR Part 61
40 CFR Part 50
Establishes air emission standards
for hazardous pollutants.
Establishes standards for ambient
air quality to protect public health
and welfare (including standards for
paniculate matter and lead).
Yes/ป
Yes/ป
Applicable to alternatives that will generate
hazardous emissions, and must meet these
requirements.
Applicable to activities that result in air
emissions during remedial activity.
Modified from Montgomery Watson 1993
AQS National Ambient Air Quality Standards UST
PSD Prevention of significant deterioration CERCLA
RCRA Resource Conservation and Recovery Act NESHAPs
POTW Publicly Owned Treatment Works
Underground storage tanks
Comprehensive Environmental Response, Compensation, and Liability Act
National Emission Standards for Hazardous Air Pollutants i
-------
TABLE A-2
IDENTIFICATION OF STATE CHEMICAL-SPECIFIC ARARs
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/
Relevant
and
Appropriate
Comment
Utah Solid and Hazardous Waste Act - Title 19 UCA Chapter 6*
Corrective Action Cleanup
Standards - CERCLA, UST
Sites
Land Disposal Restrictions
(LDRs)
Criteria for the Identification
and Listing of Hazardous
Waste
Cleanup Action and Risk-
Based Closure
Groundwater Quality
Protection Standards
R3II-2II
UAC
R3I5-I3
UAC
R3 15-2-1
UAC
R3I5-IOI
UAC
R3I7-6
UAC
Corrective action cleanup standards policy for
CERCLA and UST sites.
Outlines land disposal restrictions for hazardous
waste. Utah incorporates federal LDRs by
reference.
Establishes solid wastes that are regulated as
hazardous wastes under the Utah Solid and
Hazardous Waste Act. Definition of hazardous
waste mirrors federal definition.
Corrective action clean-up standards policy.
Details, standards, classes, protection levels, and
implementation criteria for groundwater
protection. Also, outlines certain activities
permitted by rule.
Yes/ป
YesA-
Yes/~
YesA-
YesA-
Lists general criteria to be considered in
establishing cleanup standards at CERCLA and
UST sites. Refer to Site Drinking Water Act
and Clean Air Act. Requires removal or control
of the source.
Hazardous wastes generated during remediation
will be subject to land disposal restrictions and
may be required to meet BOAT technologies
and/or constituent concentrations.
If wastes generated during the remediation phase
are determined to contain hazardous constituents,
they will be subject to these requirements.
Lists general criteria to be considered in
establishing clean-up standards. Refer to Safe
Drinking Water Act and Clean Air Act.
Requires removal or control of the source.
Groundwater quality protection standards will be
applicable for all remediation alternatives.
Utah Air Conservation Act - Title 26 UCA Chapter 1 3
State Emission Standards Tor
Control of Installations .
R307-1-3
UAC
Specifies standards for six pollutants PM|0' SO2,
CO, ozone, NO2, and lead. State adoption of
federal-AQS and BACT.
YesA-
Emissions from the remediation process will be
subject to the standards for the six pollutants.
-------
TABLE A-2
IDENTIFICATION OF STATE CHEMICAL-SPECIFIC ARARs
(CONTINUED)
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/
Relevant
and
Appropriate
Comment
Emission Standards
R307-I-4
UAC
Establishes standards for participate matter and
opacity as well as fugitive emissions and VOCs in
non-attainment areas. Rule also details unavoidable
breakdown criteria, fugitive dust requirements.
Yes/--
Remediation strategies that include pollutant
emissions must meet partkulate matter and
opacity standards. Since Davis County is a non-
attainment area for ozone, VOC standards must
be met. Davis County is not non-attainment for
participate matter. Fugitive dust requirements
must also be met.
State NESHAP Siandards
R307-IO
UAC
Establishes air emission standards for hazardous
pollutants.
Yes/-
Applicable to alternatives that will generate
hazardous emission; these emissions must meet
these requirements.
Modified from Montgomery Waison 19V3
AQS National Ambient Air Quality Standards UST
PS D Prevention of sign! (leant deterioration CERCLA
RCRA Resource Conservation and Recovery Act NESH APs
POTW Publicly Owned Treatment Works BACT
NSPS New Source Performance Standards
Underground storage tanks
Comprehensive Environmental Response, Compensation, and Liability Act
National Emission Standards for Hazardous Air Pollutants
Best Available Control Technology
-------
TABLE A-3
IDENTIFICATION OF FEDERAL ACTION-SPECIFIC ARARs
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/
Relevant
and
Appropriate
Comment
Solid Waste Disposal Act -42 USC งง6901-6987 '
General Facility Standards
Standards of Preparedness
and Prevention
Contingency Plan and
Emergency Procedures
Manifest System,
Recordkeeping, and
Reporting Requirements
Requirements for Releases
From Solid Waste
Management Units
Closure and Post-Closure
Standards
Standards for Corrective
Action Management Units
and Temporary Units
40 CFR Part 264,
Subpart B
40 CFR Part 264,
Subpart C
40 CTR Part 264,
Subpart D
40 CFR Part 264,
Subpart E
40 CFR Part 264,
Subpart F
40 CFR Part 264,
Subpart G
40 CFR Part 264,
Subpart S
(264.552 and 264.553)
Establishes general facility management
standards for hazardous waste treatment,
storage, and/or disposal facilities. .
Establishes requirements for preparedness
and prevention at hazardous waste
treatment, storage, and/or disposal
facilities.
Establishes requirements fora
contingency plan and emergency
procedures at hazardous waste treatment,
storage, and/or disposal facilities.
Establishes requirements for the manifest
system as well as for recordkeeping and
reporting at hazardous waste treatment,
storage, and/or disposal facilities.
1 Mishes requirements for detection
in; i containment of releases from waste
management units at hazardous waste
treatment, storage, and/or disposal
facilities.
Establishes general standards for closure
and, if required, post-closure at hazardous
waste treatment, storage, and/or disposal
facilities.
Establishes operational requirements for
corrective action
No/Yes
No/Yes
No/Yes
No/Yes
No/Yes
No/Yes
No/Yes
Facility management plans may be developed,
as needed, to implement other 40 CFR Part
264 requirements.
Preparedness and prevention measures may be
developed, as needed, to implement other 40
CFR Part 264 requirements.
A contingency plan and emergency procedures
may be developed, as needed, to implement
other 40 CFR Part 264 requirements.
Not a substantive requirement. Requirements
for the manifest system, recordkeeping, and
reporting may be developed, as needed, to
implement other 40 CFR Part 264
requirements.
Groundwater monitoring and source control
requirements are relevant and appropriate.
Closure and, if required, post-closure will be
needed for any remedial action.
Relevant and appropriate for alternatives in
which a temporary onjsitc treatment unit is
established.
-------
TABLE A-3
IDENTIFICATION OF FEDERAL ACTION-SPECIFIC ARARs
(CONTINUED)
Standard, Requirement,
Criteria, or Limitation
Miscellaneous Units
Air Emissions Standards
Land Disposal Restrictions
Standards to Control
Discharge through POTWs
Citation
40 CFR Part 264,
Subpart X
40 CFR Part 264,
Suhparts AA and BB
40 CFR Part 268
40 CFR Part 403
Description
Establishes design and operational
requirements for miscellaneous hazardous
waste management units
Establishes monitoring and recordkeeping
requirements for process vents and
equipment leaks.
Establishes ha/ardous wastes that are
restricted from land disposal and
describes those circumstances where
trcalcd waste may be land disposed.
Establishes standards application
requirements and permit conditions, and
provisions for discharge to a POTW.
Applicable/
Relevant
and
Appropriate
Yes/--
No/Yes
Yes/--
Yes/-
Comment
Applicable for on-site treatment units.
Equipment will be monitored in accordance
with the requirements of these subparts.
Hazardous wastes generated during
remediation will be managed in accordance
with the requirements of this part.
Applicable to generated wastes that are
discharged to the IWTP (a permitted facility).
Modified from Montgomery Watson 1993
AQS National Ambient Air Quality Standards
PSD Prevention of significant deterioration
RCRA Resource Conservation and Recovery Act
POTW Publicly Owned Treatment Works
UST Underground storage tanks
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
NESHAPs National Emission Standards for Hazardous Air Pollutants
-------
TABLE A-4
IDENTIFICATION OF STATE ACTION-SPECIFIC ARARs
Department, Division
or Commission
Statute
Subject
Applicable/
Relevant and
Appropriate
Comment
UCA 73-3-25
State Engineer,
Department of Natural
Resources
R655-4
UAC
Establishes standards for
drilling and abandonment
of wells.
Yes/~
Remediation strategies may include
ground-water and soil moisture
monitoring.
Utah Air Conservation Act - Title 26 UCA Chapter 13
State Emission Standards
for Control of Installations
Emission Standards
R.107-1-3
UAC
R 307- 1-4
UAC
Specifies standards for six
pollutants PM i(r SO2, CO,
ozone, NO2, and lead. State
adoption of federal-AQS and
BACT.
Establishes standards for
paniculate matter and
opacity as well as fugitive
emissions and VOCs in
non-attainment areas. Rule
also details unavoidable
breakdown criteria, fugitive
dust requirements, and
State NESHAPs.
Yes/-
Yes/~
Emissions from the remediation process
will be subject to the standards for the six
pollutants.
Remediation strategies that include
pollutant emissions must meet particulate
matter and opacity standards. Since
Davis County is a non-attainment area for
ozone, VOC standards must be met.
Davis County is not non-attainment for
particulate matter. Fugitive dust
requirements must also be met.
Utah Solid and Hazardous Waste Act - Title 19 UCA Chapter 6
Definitions and General
Requirements for Solid
and Hazardous Waste
Hazardous Waste
Generator Requirements
R315-1
R315-2
UAC
R315-5
UAC
Outlines general
requirements and provides
definitions for Utah Solid
and Hazardous Waste
Regulations.
Outlines requirements for
generators of hazardous
waste.
Yes/ป
Yes/~
General requirements and definitions will
be applicable for the management of solid
and/or hazardous waste.
Generator requirements will be applicable
for all hazardous wasfe generated during
remediation.
-------
TABLE A-4
IDENTIFICATION OF STATE ACTION-SPECIFIC ARARs
(CONTINUED)
Department, Division
or Commission
Requirements for
Hazardous Waste Facilities
Ground Water Protection
Rule
Miscellaneous Units
Requirements for
Corrective Action
Management Units
Land Disposal Restrictions
Clean-up action and risk-
based closure standards
Statute
R3I5-8
UAC
R3 15-8-6
UAC
R3 15-8- 16
UAC
R3I5-8-2I
UAC
R3I5-I3
UAC
R315-101
UAC
Subject
Establishes general
requirements for facility
management and specific
requirements for hazardous
waste management units.
Provides for the protection
of ground water at
hazardous waste sites.
Establishes design and
operational requirements
for miscellaneous
hazardous waste
management units.
Establishes requirements
for operations of Corrective
Action Management Units
and Temporary Units
Outlines land disposal
restrictions for hazardous
waste. Utah incorporates
federal LDRs by reference.
Provides a framework for
using risk-based standards
in remediating RCRA sites
Applicable/
Relevant and
Appropriate
Yes/~
Yes/--
Yes/--
Yes/~
Yes/~
Yes/~
Comment
General facility management plans
(R3 15-8-2 through R3 1 5-8-4) may be
developed, as needed, to implement other
requirements of R315. Standards for
ground water protection (R3 15-8-6);
closure and post closure (R3 15-8-7); use
and management of containers (R3I5-8-
9); tanks (R3 15-8- 10); and miscellaneous
units (R3 15-8- 16) may be applicable
depending on the remediation strategy.
Remediation strategy must be protective
of ground water and provide a monitoring
program.
Applicable for on-site treatment units.
Requirements applicable to corrective
actions where generated waste are stored
or temporarily stored and managed
Hazardous wastes generated during
remediation will be managed in
accordance with the requirements of this
rule. ,
Remediation strategy must achieve
compliance with risk-based closure
standards.
-------
TABLE A-4
IDENTIFICATION OF STATE ACTION-SPECIFIC ARARs
(CONTINUED)
Department, Division
or Commission
Statute
Subject
Applicable/
Relevant and
Appropriate
Comment
Corrective action clean-up
standards policy UST
and CERCLA sites
R311-211
UAC
Specifies the State of
Utah's policy for cleanup at
UST and CERCLA sites.
Yes/--
Remediation strategy must achieve
compliance with risk-based closure
standards.
Utah Water Pollution Control Act - Title 26 UCA Chapter 11
Groundwater Quality
Protection Standards
R3I7-6
UAC
Details, standards, classes,
protection levels, and
implementation criteria for
groundwater protection.
Also, outlines certain
activities permitted by rule.
Yes/--
Groundwater quality protection standards
will be applicable for all remediation
alternatives.
Utah Pollutant Discharge
Elimination System
(UPDES)
R3I7-8
UAC
Details, standards,
application requirements,
and permit conditions and
provisions for discharge of
any pollutants from a point
source into any water
system in the state.
Yes/-
All liquid waste will be required to be
discharged to a permitted treatment
facility.
Modified from Montgomery Watson 1993
AQS National Ambient Air Quality Standards
PSD Prevention of significant deterioration
RCRA Resource Conservation and Recovery Act
POTW Publicly Owned Treatment Works
UST Underground storage tanks
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
NESHAPs National Emission Standards for Hazardous Air Pollutants
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PUBLIC MEETING TRANSCRIPT
Appendix B
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OUR FILE NO. 54298-060
COMMUNITY MEETING
HILL AIR FORCE BASE
OPERABLE UNIT 7
V
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1 *****
2 Community Meeting of Hill Air Force Base regarding
3 Operable Unit 7, held on Wednesday, March 1, 1995,
4 7:15 p.m., at the Base Theater, Hill Air Force
5 Base, Ogden, Utah.
6
7 *****
8
9 IN ATTENDANCE: Colonel Larry Wheeler
10 Ms. Gwen Brewer
11 Mr. Steven Hicken
12 Mr. Rob Stites
13 Capt. Gary Chesley
14 Mr. Greg Steven
15 Mr. Jerry Mansfield
16 Ms. Nan Tate
I"7 Mr. Albert BadeaO
18 Ms. Vickie L. Wheeler
19 Ms. Diane Simmons
20 Mr. Harold Dunning
21 Mr. Andrew Gemperline
22 Mr. George Srader
23 Mr. Dave Fulton
24 Ms. Traci Thomas
25 Other members of the public
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,1 OGDEN, UTAH, WEDNESDAY, MARCH 1, 1995 - 7:15 P.M.
2 *****
3 MS. BREWER: We appreciate that you
4 have...(inaudible).
5 THE REPORTER: I can't hear you.
6 MS. BREWER: I think we'd better start go ahead
7 and get started, just to go through the meeting so we can
8 have it recorded there come some people.
9 (Laughter)
10 This is really one of the larger groups that we've
11 had. We're really happy to see all of you. We'll give you
12 a good opportunity to meet our new Wing Commander, Colonel
13 Larry Wheeler. I hope you will all get behind him, and if
14 you have any questions, he will answer them for you.
15 So, Commander Wheeler.
16 CMDR. WHEELER: Since it is such a large mass of
17 public folks that... (inaudible)...things of that nature, I
18 don't think it will
19 THE REPORTER: I can't hear you.
20 CMDR. WHEELER: come to this Air Force base.
21 On behalf of General Condon, we are pleased we had the
22 opportunity to get everybody here'to our Air Force base,
23 give you an opportunity for public comment. We have a
24 ...(inaudible)
25 THE REPORTER: I can't hear you. Please use the
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 raic.
2 CMDR. WHEELER: on hand that is going to
3 comment about our plan for the Operating Unit No.7 and our
4 proposed plan, what we're going to do to clean up this
5 particular area.
6 This area that we're interested in is exclusively
7 on the base. It is under if you're familiar with the
8 base, under Hangar 225 or Building 225. It will be his
9 proposal and the proposal at Hill Air Force Base on how to
10 do the cleanup. !
11 So, Steve Hicken, come up here and tell us how you
12 are going to do that. After you talk awhile, we'll have it
13 available for questions and answers and any additional
14 information.
15 You want to start, Steve?
16 MR. HICKEN: Thank you, Colonel Wheeler.
17 Most of you are already fairly familiar with
18 Operable Unit 7. For others of you, this will be an
19 education in process. So actually, I think it is a good
20 exercise to go through this.
21 Before I begin tonight, just for those of you who
22 may not know, we do have representatives without getting
23 into individuals, we do have representatives of the EPA,
24 State Department of Environmental Quality, representatives
25 to Hill Air Force Base...(inaudible)
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 THE REPORTER: I can't hear you.
2 MR. HICKEN: and so we're well represented here
3 tonight.
4 We also have quite a crew here from Montgomery
5 Watson, who was the prime contractor for Operable Unit 7 and
6 had done the majority of the work for us here on the base.
7 I'm going to try to avoid using acronyms tonight.
8 It has become so ingrained for us, sometimes we slip. If I
9 use them, the first time I will try to define them. If I
10 don't, you can call me on that. And if I could ask that we
11 please defer questions until the end. It is not a very long
12 presentation, but if we could just hold the questions to the
13 end, we can then go back to any of the overheads you might
14 like to see again.
15 For the past four years, we have been carrying out
16 an investigation at Operable Unit 7, and under the auspices
17 of EPA and the State department of Environmental Quality.
18 This has been carried out in phases. We have just closed
19 the remedial investigation and feasibility study, RI/FS.
20 Can we have the first slide, please.
21 MS. BREWER: If any of you don't have the
22 material, you can have a. copy of this if you would like to.
23 MR. HICKEN: This first slide shows the objectives
24 we have tried to accomplish during the RI/FS process on
25 Opperable Unit 7. collect data to characterize site
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
conditions. And second was to determine the nature and
extent of soil contamination. Third was to evaluate risks
to human health and environment.
From those objectives, determine cleanup
alternatives and take those cleanup alternatives and select
a preferred alternative based on EPA requirements.
Part of the reason for this meeting tonight is
81 to partially, is to obtain community acceptance.
Let's go to the next slide. This next slide shows
10 Hill Air Force Base in relation to Operable Unit 7. As you
11 can see, there are a number of operable units. We've shown
12 them all on the slide. There are eight currently.
13 As you can also see, most of them are around the
14 perimeter of the base. Operable Unit 7 is different in this
15 regard. It is in the heart of the industrial complex area.
16 It consists of Buildings 225, 220 and Base Supply Well 6.
17 Base Supply Well 6 is off to the northwest of the main
18 runway at the top.
19 I should say at this point, OU 7 is the soils only
20 under the operable unit. The groundwater you can see
21 beneath the box that represents the heart of Operable Unit
22 7, that groundwater is being treated under Operable Unit 8.
23 So, this will only deal with soil remediation.
24 This next slide shows Buildings 225 and 220 in
25 more detail. As you're probably aware, Building 225 is the
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
primary maintenance hangar for the base. It has been in
operation since the 1940's. Areas we have investigated in
Building 225 include the former metal plating shop. This
shop was used from the 1940's until about the 1970's, and
plating solutions composed of a variety of chemicals, acids,
base metals, solvents that were discharged through a floor
grate system that eventually developed some leakage.
8 We also investigated a PCB area, the location of a
former transformer. You can see it immediately to the west
10 of the plating shop area. That was moved in the 1960's.
11 Here again, we got some leakage from that transformer that
12 discharged some PCB-containing liguids into the soils
13 beneath the building.
14 We also investigated some miscellaneous areas of
15 Building 220. These included a wash rack, a hydraulic room,
16 a mop cleaning room and former degreaser pit. These were
17 particular, areas that former workers within 225 record that
18 chemicals had been used in the area or discharged in the
19 grates, or we expected might have been. They were likely
20 areas that some contamination might have been.
21 On the same slide, up to the northeast is Building
22 220. And Building 220 has been the primary stripping and
23 cleaning facility for the base from 1957, and still is
24 today. Paints, paint thinners, strippers, solvents and
25 other chemical wastes are discharged through a floor drain
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
system that then connects to the industrial waste pipeline.
Historically, much larger volumes of liquid waste were
discharged in that system.
-As many of you are aware today, we do the majority
of our heavy stripping by using a bead blast operation which
is completely dry.
There was an investigation in 220, including three
8 paint chip settling tanks on the northwest of the building.
These were the tanks that received the discharge from those
10 industrial lines.
11 We also investigated a 20,000 gallon diesel tank
12 just immediately to the other end of the discharge tanks,
13 the settling tanks. We also investigated the industrial
14 discharge lines that go underneath the building and flow
15 into those tanks.
16 in 1986, those three tanks and the diesel storage
17 tanks were all removed. We are now connected directly to
18 the industrial waste line. At the time of the removal of
19 those tanks, we found some contamination of the soil at that
20 time.
21 The next slide shows a picture of the Base Supply
22 Well 6. What happened at Base Supply Well 6 is that, during
23 construction of the subsurface of the building, trench 225,
24 that trench happened to cut through a portion of the old
25 plating shop. In fact, this is how the contamination was
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
originally discovered there. Some of those soils from that
trench were taken out to Base Supply Well 6 and used as
backfill over the trench. So, we did some investigation to
determine if there was contamination present.
This next figure shows a conceptualized model for
Operable Unit 7. As I mentioned, in Building 225, the
plating shop did discharge some of those wastes into the
soils beneath. Some of those contaminants actually made it
to groundwater, and that is really the bulk of the
10 contamination that is present in Building 225, and the one
11 we're most concerned with.
12 The PCB area that I mentioned, at the time that
13 PCB contamination was discovered, it was actually during the
14 installation of another utility trench. At the time it was
15 discovered, a significant quantity of the soil was removed.
16 Approximately 95 tons were removed and disposed of in a
17 proper facility. We believed from that, that the bulk of
18 the contaminations were removed, because our borings in that
19 area discovered only minor amounts of contamination
20 remaining. Also, in the miscellaneous areas, we were only
21 able to detect minor amounts of VOC organic compounds. I
22 mean, solvents like TCE, TCA, things we used as degreasers
23 or solvents.
24 At Building 225, we also found a very low level of
25 contaminants were detected in the soils beneath the
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
building. And Base Supply Well 6, we found very minor
amounts of contamination.
Although we did identify soil contamination at
every site at Operable Unit 7, comparison of the types and
concentrations of these compounds with health-based
standards provided by the EPA show that the former metal
plating shop was the only area that poses any risks to human
8 health or the environment.
Although we do have detailed information on the
10 sites, these other sites where the compounds were detected
11 there, we're going to kind of leave that and focus on the
12 plating shop area right now.
13 Let's go to the next slide. Before we do that,
14 though, one thing I want to make sure is clear. This is a
15 model showing the groundwater beneath Hill Air Force Base.
16 This is kind of generalized, but it is to scale, showing the
17 approximate depths of the aquifers that exist below Hill Air
IS Force Base.
19 I mentioned that the contamination from the
20 plating shop had reached groundwater and that is true. The
21 groundwater we are referring to is the shallow aquifer right
22 there at the very top. Between that and the next aquifer
23 down is a clay layer, and then you hit the Sunset aquifer,
24 and then another clay layer and...(inaudible)... aquifer.
25 Those are hundreds of feet deep, and since it is the Sunset
10
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
and Delta aquifers that are tapped for drinking water, right
now, we are not contaminating any aquifers that are used for
drinking water. It is only that shallow, upper aquifer that
has been contaminated.
This figure summarizes the types of chemicals
detected and the frequency of detection and maximum
concentrations observed in Building 225. And as you can
see, hexavalent chromium and cadmium are highlighted in
yellow. These are the only compounds that were detected in
10 concentrations that would cause a risk to on-site workers or
11 future residents if they were exposed to these soils.
12 Other compounds were detected, but they were not
13 in high enough concentrations to pose a risk. Total
14 chromium, lead, cyanide, and those last four are organic
15 compounds or V-o-C's. Based on that, we would like to focus
16 in on hexavalent chromium and cadmium.
17 This is what we call an isoconcentration map.
18 All this is doing is looking down, kind of a plan view,
19 looking at the aerial here, hexavalent chromium. As you can
20 see, there are two specific zones of contamination, one in
21 the north and one in the south. These just happen to
22 coincide with the area where chromium plating took place.
23 Next slide, please. This shows the cadmium
24 concentration. Very similar looking in the south area. We
25 again have two distinct areas, but the north area is very,
11
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 very slight contamination with the highest concentrations in
2 that south area.
3 Next slide. This shows a cross-section, north to
4 south, cut through the plating shop area so that you can now
5 see the vertical distribution of these contaminants. The
6 majority of the contamination is confined in the upper 50
7 feet. The cadmium is not shown here. This shows the
8 hexavalent chromium. But if you can remember from the
9 previous slide, the majority of it is focused on the plume
10 area to the right. It would have a similar vertical
11 distribution but of lower concentrations. Hexavalent
12 chromium is the highest of the concentrations of the metals.
13 This also shows the soils condition beneath the
14 building. It is very fine sands with intermittent levels of
15 fine silts and clays. Those silts and clays are the darker
16 streamers that you see going across. That has had a
17 significant impact on what's happened here because that...
18 (inaudible)...precipitated that movement downwards. The
19 bulk of the contamination is trapped right above those clay
20 layers in those upper areas.
21 So, although we know the contamination has reached
22 the groundwater, the majority of the mass is still captured
23 above the clay layers. Since the plating shop was removed
24 in 1972, the discharges to that line have stopped. We no
25 longer have any solutions flowing underneath that building.
12
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
As a result, the conditions there have become very dry. We
verified this during our early program. Knowing what these
dry conditions are, we don't believe any further migration
of contaminants is taking place right now.
Let's move on to the risk assessment summary.
This is part of the remedial investigation and feasibility
study that takes place. To give you a little background,
8 this shows the three components of a human health risk
assessment.
10 First is to identify, chemicals of concern that we
11 have at the site. The second is to do an assessment of how
12 exposure to either humans or animals can take place from
13 these chemicals. Exposure, like ingesting the soil that's
14 contaminated or drinking water that is contaminated, that is
15 an exposure scenario. At the same time, looking at toxicity
16 assessment toxicity is how toxic these are. When you
17 put these three steps together, you end up with a complete
18 risk characterization for the site and the compounds there.
19
20 This next slide shows the summary for Operable
21 Unit 7. As you can see, we looked at current health risk to
22 workers in the building, and also future risk to
23 construction workers or "residents who might be living there.
24 The findings of this study show that no current health risk
25 exists on that site. I should say, under current health
13
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 risk, there is a little different rationale why there is no
2 current health risk.
3 In the case of PCB in the Base Supply Well 6 and
4 Building 220, the reason there is no health risk is just on
5 low concentration. They are not high enough concentrations
6 to form a risk.
7 in the case of the former metal plating shop,, the
8 reason we have no current risks in there, we have 12 to 18
9 inches of concrete separating that contamination from our
10 workers who are maintaining airplanes above that.
11 When we go to the future, we will show where the
12 former metal shop does pose a risk. If the construction
13 workers come in, break through the floor, they can become
14 exposed to the soils. Dermal contact or dust or ingestion,
15 that's a possibility. That's a substantial threat. If the
16 property were ever to be sold and that building removed and
17 turned over to residential use, you have the possibility
18 then of people who are constructing a house to be exposed.
19 The homes would be exposed and also the residents who work
20 around their homes in their gardens or on their homes. That
21 is what poses the future health risk at Operable Unit 7.
22 Let's go to the next one. Let's talk for just a
23 few minutes about selection of our cleanup alternatives.
24 These are determined by considering technologies, cleanup
25 technologies that may be applicable. Once they have been
14.
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
identified, they are assembled into alternatives that will
address the needs we have at Operable Unit 7. We do a
comparative analysis of the alternatives based on nine
alternatives established by EPA.
This next slide shows those nine criteria. The
first criteria, and the most important, is overall
protection of human health and environment. That is the
number one thing.
The second is compliance with applicable or
10 relevant or appropriate requirements. That is called ARARS,
11 and that is kind of a mouthful and not easy to understand.
12 But these are laws, like groundwater or drinking water
13 protection laws. Those first two requirements, two criteria
14 are called threshold criteria. Any alternatives that we
15 look at have to meet at least those two criteria.
16 The next five are what is called balancing
i
17 criteria. In Operable Unit 7, we will see implementability j
i
18 is the most important of the balancing criteria. And i
19 finally, we have state acceptance and community acceptance. !
20 Let's go through the alternatives. Alternative j
i
21 No. 1 is No Action, and inclusion of a "no action" !
22 alternative is required by the EPA. What it is, it sets a |
23 basis for the comparison with the other alternatives.
24 The component that is first, there will be no
25 cleanup action taken. However, there will be groundwater
15
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 monitoring and soil moisture monitoring. Groundwater
2 monitoring will take place from standard monitoring wells,
3 upgradient of the contamination right in the midst of this,
4 and downgradient soil monitoring will be done with neutron
5 probes that'll be, again, in the zone of contamination, to
6 make sure we have those dry conditions that we talked about
7 maintained. We don't have a significant amount of water
8 precipitation coming down through there. The building and
9 floor are acting as a deterrent for that kind of thing
10 happening.
11 It also includes a five-year review standard for
12 SERCLA, for SuperFund sites for cleanup. Every five years,
13 we want to come back in and take a look again at the
14 alternatives that we've selected. See if it is still
15 viable. See if it is still protecting and doing the things
16 we want to do. The cost of this alternative, over a 30-year
17 period, is approximately $500,000.
18 Right now, this alternative can be implemented and
19 it would cause virtually no interruption to the operations
20 in Building 225. But it is not protective of human health
21 and does not meet ARARS for groundwater. It is not
22 protective of the groundwater.
23 Let's go to the next alternative. This is
24 Alternative No.2, and this is Institutional Controls. This
25 contains the same components as for Alternative No.l, except
16 .
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
for the first three bullets there. That is issuing a
continuing order by the Base Commander. What this will do
is, it will restrict development and access to contaminated
areas.
We essentially have this in place right now.
Anytime construction takes place in Building 225, an order
is put through, or a request, and it goes through our
office. In that way, if they are going to be breaking
through the floor, we will know about it and we can then
10 warn them if they are in an area of contamination so that
11 they can be properly protected. Both the construction
12 workers and also the workers...(inaudible)...them.
13 It also entails maintaining the concrete floor in
14 the building. That is the key to that alternative, is
15 keeping that floor in good shape and in place.
16 Also, filing a notice to the Deed by Hill Air
17 Force Base, if the property ever changes hands. That way,
18 the new owner will be aware that there is contamination
19 present.
20 And also, warning signs in the area. These will
21 be similar like warnings for electrical lines or things
22 like that. Just a warning that there is contamination
23 beneath the floor, should that floor seal be broken or if
24 they break through the soil beneath.
25 Cost for this alternative, over a 30-year period,
17
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
was $627,000, and this can be implemented under the current
site conditions.
Alternative 3 is the first of the active
alternatives where we're actually taking action to actually
remove the contamination. And this alternative includes
excavation and removal of all contaminated soils and...
(inaudible)...helps. The excavated soils would be placed in
8 the hazardous waste landfill. And this alternative is not
currently viable as implementation would require removal of
1.0 a large portion of Building 225, and probably a disruption
11 of the work that went on in the rest of the building. It is
12 not implementable right now in the current conditions.
13 The cost for this one is very high, over $7 million
14 over a 30-year cost.
15 This is alternative 4, Excavation and Soil
16 Washing. This involves removal of contaminated soils; that
17 is, soils that pose a risk to human health. Only, in this
18 case, those soils will be treated on site by washing. The
19 soils will be put back into the original hole.
20 As Alternative 3, it is not currently
21 implementable while Building 225 is in place because of the
22 size of the excavation that would be required to go down
23 that 50 feet to get those soils that pose a risk. And
24 again, this is a fairly expensive alternative at over
25 $5 million.
18
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
Our last alternative is Alternative 5. This is
In-Situ Solidification. Essentially, what in-situ
solidification involves is taking the soils that pose a risk
and mixing them with a solidifying agentr such as concrete
or fly ash. This creates a solid block that's thoroughly
impermeable to leaching those metals out. That block is
placed right back there in the original place that it is
now, but it would require continued monitoring to make sure
that we don't have leaching out from that block.
10 This alternative would cost approximately
11 $2 million to implement. But there again, we're looking at
12 an alternative that would require the removal of a good
13 portion of Building 225 to see this alternative
14 accomplished.
15 Based on these site conditions and the need to
16 keep the facility in Building 225 working and operational,
17 and considering the current lack of risk to on-site workers,
18 Hill Air Force Base proposes that Alternative No. 2 be the
19 preferred alternative. This alternative can be implemented
20 under the current conditions. It can still meet the
21 requirements of those threshold criteria. It is protective
22 of both human health and also the groundwater aquifer
23 conditions, and also meets the state and federal
24 regulations. If site conditions ever change, if the
25 building should be removed, then other alternatives will
19.
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 have to be looked at and other actions taken at that time.
2 This next figure just shows some of the components
3 of Alternative No.2. As I said, we would have monitoring
4 wells upgradient, in the midst of the contamination plume,
5 and then downgradient. What we would be looking for is
6 significant increases in the concentrations of the metals in
7 the groundwater. This would be an indication that we
8 actually had some continuing transport of groundwater. Soil
9 moisture monitoring would give us the second checkup on
10 that. What it would do is merely to examine the soil
11 moisture within that zone to make sure we are not seeing the
12 radical increases that would be indicative of things like
13 rain water or infiltration coming through that could then
14 dissolve those metals and mobilize them and carry them to
15 the groundwater. It is kind of the double-check to make
16 sure we're keeping those dry conditions in place.
17 AS I stated earlier, this alternative is currently
18 implementable, does meet the requirements. In the event
19 that conditions ever do change, then we would obviously have
20 to look at other actions if the building were removed.
21 Are there any questions that I can answer?
22 George?
23 MR. SRADER: Do you have any idea or any estimate
24 of the relation of time that the...(inaudible)...building
25 would be used .to last, or when this might be reviewed?
20 .
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
MR. HICKEN: Reviewed again? Is there anyone
here who knows how?
CMDR. WHEELER: I don't think we do. Much of that
just depends on probably what happens on even the global
scale. You know, with the cold war going away, we've
obviously seen some changes as far as what our national
level of defense is, and we were even anticipating that
there was the possibility that Hill would come out on the
Base Realignment and Closure list, but it was released today
10 and it was not on the list. There is every indication that
11 the building would stay in operation for the future that we
12 know of.
13 MR. .HICKEN: Any other questions?
14 MR. . SRADER: On your monitor points, those are
15 wells that are in the ground now, and usable?
16 MR. HICKEN: We have the well right now that is in
17 the midst of that contamination that was put in during the
18 investigation. We have an upgradient well. We would have
19 to put another downgradient well closer'to the site. So, we
20 would probably have one or two more wells that we would need
21 to put in right now. Right now, we don't have any available
22 borings for the soil moisture monitoring. That would have
23 to be done.
24 We've done...(inaudible) ...the building before.
25 Obviously, we were doing remedial investigation. It takes
21
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
some coordination, but it has been able to be done and there
has been a lot of cooperation with those who supervise
Building 225 work. There is work to be done, but part of it
is in place and part of it yet has to be put in.
MR. MANSFIELD: Jerry Mansfield. Steve, I think
it is important that you make it clear that the costs of
Alternatives 3 through 5 do not include removal of the
building for that remediation.
MR. HICKEN: That's correct. As high as those
10 costs are, they do not include the cost that would be
11 incurred by the Air Force to remove that operation. I
12 really don't have an estimate of what that would be, but
13 that would be very high, to build another facility like that
14 to take care of that operation. Thanks.
15 MR. SRADER: Are these monitoring wells, or the
16 ones that you have, sufficient to indicate or to show there
17 is no migration or show what migration might be in the
18 future, as you are monitoring those places?
19 MR. HICKEN: We've discussed that and I think,
20 alone, you might have a difficult time. If you only had the
21 monitoring wells, you would be
22 MR. SRADER: You are looking at one point that is
23 fixed.
24 MR. HICKEN: That is why we have an upgradient and
25 a downgradient well. We do have other wells around the
22
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
area, and those receive standard monitoring, on the base.
So, we really do have a feel.
If we see those concentrations rise in the
groundwater, yeah, we can say: Okay, it must be coming from
water contamination. However, without that soil moisture
monitoring, we wouldn't be certain. Maybe there is another
source that we have not found. But that soil moisture
monitoring gives us a second opinion, a second piece of data
to say: Hey, we had significant increase in soil moisture
10 here six or seven months ago and now we are seeing a
11 subsequent rise in groundwater concentrations. It makes
12 sense, we're getting transport. If we see a rise of
13 groundwater and we have dry conditions up here, we will be
14 suspicious that perhaps there is another source somewhere.
15 So, is it sufficient? I think so. I think it is.
16 MR. SRADER: Are you going to be monitoring around
17 the edges of the slab, to get some idea where to find if
18 there is, at some later date, a migration out from beneath
19 the slab?
20 , MR. HICKEN: Migrating?
21 MR. SRADER: Just to check that you are not
22 getting any migration out from under the slab. Are you
23 monitoring the edges of the slab?
24 MR. HICKEN:: We will have soil moisture probes
25 out there, yes. So, those probes will kind of act as our
23
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 guide for the soils, to make sure that they are still
2 maintaining the dry condition. Yes, there will be
3 monitoring done, yes.
4 MR. SRADER: How about, are you monitoring the
5 chromium concentration?
6 MR. HICKEN:: We won't be pulling soil samples.
7 We already accomplished that in the remediation, quite a
8 significant number. We feel we have a good handle on the
9 zone of contamination, enough to make the decisions we are
10 making now. If that building is removed, we will probably
11 have to do some additional characterization work, because we
12 will now have that wide open station. Then we will go
13 anywhere we want to poke holes in it. At that time, there
14 would be more characterization work done.
15 MR. SRADER: You are presuming that the monitoring
16 of the soil moisture is adequate to show there is no further
17 migration?
18 CMDR. WHEELER: I think that is the whole premise
19 here, while that soil is dry, that there is no migration.
20 Hence, we have the moisture monitors that show that they
21 continue to stay dry, then.there would be no migration. If
22 all of a sudden there is some type of indication of
23 moisture, then that would allow some type of migration. At
24 which time, they would, you know, raise the level of local
25 investigation or go back in and see what would be causing
24
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 that.
2 MR. HICKEN:: We would have to revisit it. If
3 site conditions change, obviously, that's something that
4 will have to be discussed. And we are having continuing
5 checks. Those two checks, we feel, will give us a good view
6 of what is going on.
7 MS. BREWER: What I was recommending, that you
8 might want to mention the groundwater is being studied under
9 a different operable unit. That would be the only way they
10 would know is if it were included in the groundwater. So,
11 right now, he is only talking about the soil, not the
12 groundwater.
13 MR. HICKEN:: The groundwater, as I said, is
14 being treated in another operable unit study.
15 Any more questions?
16 MS. BREWER: No questions? Jerry, would you like
17 to say something?
18 MR. STITES: Generally, we support the action.
19 CMDR. WHEELER: Any comments from any of the folks
20 in support of the conditional things that you want to bring
21 forth? We will just note it in the public record. You're
22 the expertise out here. Now is the time to say it. Right
23 back here.
24 MR. FULTON: David Fulton. You mentioned the fact
25 that the OU 7 lies within the larger groundwork and you have
25
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
1 constant monitoring?
2 MR. STITES: That was in there.
3 CMDR. WHEELER: Anything else? Well then, all I
4 would say.is, thank you very much for coming out tonight.
5 We were hoping that we might have a few more interested
6 public, but in light of the release of information on the
7 BRAC closure, maybe everybody is home celebrating tonight.
8 Who knows. Thank you for coming out. Thank you for
9 demonstrating your interest. Thank you for the questions.
10 That allows us, as far as showing on our record, that some
11 folks were interested in having an opportunity to address
12 some of their questions.
13 So, if there are no other questions, we would
14 bring this to a close this evening. Thank you.
15 MS. BREWER: We do have some materials up here and
16 if any of you haven't signed in, please sign in to make that
17 a part of the record.
18 *****
19 (Whereupon the meeting was concluded.)
20
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PUBLIC MEETING RE OPERABLE UNIT 7 AT HILL AFB, 3-1-95
REPORTER'S CERTIFICATE
STATE OF UTAH )
) ss.
COUNTY OF SALT LAKE }
I, SHIRLYN SHARPE, R.P.R., C.M. and Notary Public
in and for the State of Utah, do hereby certify;
That the foregoing transcript of the Public
10 Meeting for Operable Unit 7 at Hill Air Force Base
11 was prepared by me from my stenographic notes taken at the
12 time of the proceedings therein reflected;
13 That the foregoing transcript represents all
14 proceedings had of record at the time of the meeting, with
15 the exception of the portions which were inaudible to me,
16 which portions are so noted in the transcript;
17 And I hereby further certify that the foregoing
18 typewritten transcript, as typed by me, is a correct record
19 of my stenographic notes so taken;
20 IN WITNESS WHEREOF, I have subscribed my name and
211 affixed my seal this 7th day of March, 1995.
22
23
24
SHIRLYfl SHARPE, RPR, CM
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WRITTEN COMMENTS AND RESPONSES
Appendix C
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APPENDIX C
No written comments were received.
C-l
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