EPA Superfund Record of Decision: Hill Air Force Base EPA ID: UT0571724350 OU 08 Hill AFB, UT


                                    EPA/ROD/R08-97/198
                                    1997
EPA Superfund
     Record of Decision:
     HILL AIR FORCE BASE
     EPA ID: UT0571724350
     OU08
     HILL AFB, UT
     09/30/1997

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EPA/541/R-97/198


                                           Hill Air Force Base,  Utah

                                           Final
                                           Record of Decision for an
                                           Interim Remedial Action at
                                           Operable Unit 8

                                           May 1997

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                          FINAL RECORD OF DECISION
                     FOR AN INTERIM REMEDIAL ACTION AT
                              OPERABLE UNIT 8
                         HILL AIR FORCE BASE, UTAH
   This is a primary document for Operable Unit 8 at Hill Air Force Base. It will be
available in the Administrative Record, which is maintained at the following locations:
                              Davis County Library
                              Central Branch
                              155 N. Wasatch Drive
                              Layton, Utah 84041
                              Hours:   Mon - Thurs:   11:00 am - 9:00 pm
                              Fri -  Sat:     11:00 am - 6:00 pm

                              Environmental Management Directorate
                              00-ALC/EMR
                              Building 5
                              7274 Wardleigh Road
                              Hill AFB,  Utah 84056-5137
                              Contact: Mr. Charles Freeman    (801)  775-6951
                           Submittal Date: May 9,1997

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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 ACTIVITIES                                       2-1

      2.1 Site History                                                            2-1
      2.2 Investigation History                                                   2-1
      2.3 Enforcement Activities                                                  2-2
      2.4 Highlights of Community Participation                                   2-2
      2.5 Scope and Role of Operable Unit 8 Within Site Strategy                  2-3

3.0 SUMMARY OF SITE CHARACTERISTICS                                               3-1

      3.1 Hydrogeologic Setting                                                   3-1
      3.2 OU 8 Source Areas                                                       3-2
      3.3 Nature and Extent of Contamination                                      3-3
      3.4 Conceptual Model of Contaminant Transport                               3-5

4.0 PUBLIC HEALTH AND ENVIRONMENTAL IMPACTS                                       4-1

      4.1 Human Health Risks                                                      4-1
      4.2 Environmental Risk                                                      4-1

5.0 DESCRIPTION OF INTERIM REMEDIAL ACTION ALTERNATIVES                           5-1

      5.1 Development of Alternative                                              5-1
      5.2 Detailed Analysis of Alternatives                                       5-2
             Alternative 1: No Action                                             5-2
             Alternative 2: Ground-Water Extraction,  Treatment with Carbon        5-2
              Adsorption, Discharge to Storm Drain
             Alternative 3: Ground-Water Extraction,  Treatment with Air           5-3
              Stripping, Discharge to Storm Drain
             Alternative 4: Ground-Water Extraction and Discharge to              5-4
              Sanitary Sewer
             Alternative 5: Ground-Water Extraction,  Treatment at IWTP,           5-5
              Discharge to Sanitary Sewer
      5.3 Comparative Analysis of Alternatives                                    5-5
             5.3.1. Evaluation Criteria                                           5-5
             5.3.2. Comparative Analysis of Alternatives                          5-7

6.0 SELECTED REMEDY                                                               6-1

      6.1 Description of the Selected Remedy                                      6-1
             6.1.1. Remediation Objectives and Performance Standards              6-1
             6.1.2. Restoration Time Frame                                        6-2
             6.1.3. Costs                                                         6-2
      6.2 Statutory Determinations                                                6-2
             6.2.1. Protection of Human Health and the Environment                6-3
             6.2.2. Compliance with Applicable or Relevant and Appropriate        6-3
                      Reguirements
             6.2.3. Cost Effectiveness                                            6-4
             6.2.4. Utilization of Permanent Solutions and Treatment Alternative  6-7
                    Technologies or Resource Recovery Technologies to the
                    Maximum Extent Practical
      6.3 Documentation of Significant Changes                                    6-7

RESPONSIVENESS SUMMARY

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REFERENCES
APPENDIX A - PUBLIC MEETING TRANSCRIPT
APPENDIX B - WRITTEN COMMENTS AND RESPONSES
                                       LIST OF TABLES

TABLE
 NO.                                TITLE

3-1  Contaminants Detected on Base in OU 8 Ground Water

5-1  Summary of ARARs for Each Alternative

6-1  Summary of ARARs for the Selected Remedy
6-2  Summary of ARARs for the Optional Remedy
                                                                                 PAGE

                                                                                  3-4

                                                                                  5-8

                                                                                  6-5
                                                                                  6-6
                                   LIST OF FIGURES
                                        TITLE
FIGURE
 NO.

1-1  Vicinity Map
1-2  Location of Operable Units

2-1  Site Map
3-1  Piezometric Surface Contour Map
3-2  TCE Isoconcentrations in Shallow Portion of the Shallow Aquifer
3-3  Ground-Water Contaminant Profile Along Southern Base Boundary
3-4  Conceptual Model of Contaminant Transport

4-1  Preliminary Exposure Pathway Diagram

5-1  Proposed Location of Ground-Water Extraction Wells and Area of
       Attainment
FOLLOWING
 PAGE NO.

      1-1
      1-1

      2-1

      3-1
      3-1
      3-4
      3-5

      4-1

      5-3
6-1  Conceptual Interim Remedial Action Implementation Schedule
                                                                                  6-1

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Site Name and Location

Operable Unit 8
Hill Air Force Base, Utah
Weber and Davis Counties, Utah

Statement of Basis and Purpose

This decision document presents the selected remedy for an interim remedial action (IRA) at Hill Air
Force Base (Hill AFB) Operable Unit 8 (OU 8) in Weber and Davis Counties, Utah. Five different interim
remedial action alternatives were evaluated 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). The selected remedy for the interim remedial action at Hill AFB OU 8 is
Alternative 4: groundwater extraction and discharge to a sanitary sewer. If greater treatment efficiency,
cost effectiveness or ease of implementability can be established at a later date, other discharge
alternatives would be considered, such as the Industrial Wastewater Treatment Plant (IWTP). This decision
is based on the Administrative Record for Hill AFB. This remedial action is only an interim measure and
will be followed by the final remedy for OU 8.

Assessment of the Site

Actual or threatened releases of hazardous substances, if not addressed by implementing the response
action selected in this Record of Decision, 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 8 are below levels considered by the
EPA to be significant. An interim remedial action is warranted based on possible future risks to human
health and the environment, to contain contaminants while further information is gathered to characterize
the site, and to evaluate possible final remedial actions.

Description of the Selected Remedy

Operable Unit 8 is one of nine OUs at Hill AFB and is in the early stages of the CERCLA process. The
remaining OUs are at various stages in the CERCLA process. As OU 8 only includes ground water, this
action will only address contaminated ground water. Contaminated soil in the OU 8 area is being addressed
by other soils-only OUs that include OUs 3 and 7. The selected remedy for an interim action at OU 8
addresses the potential future threat to human health and the environment by preventing the transport of
contaminated ground water to off-Base locations where exposure may occur. This interim action is planned
to be in operation until the final remedy for OU 8 is implemented (anticipated to be within six years).
This area and other areas containing ground-water contamination at OU 8 will be addressed by the final
remedy for OU 8. The major components of this interim remedy for OU 8 include:

• Contain contaminated ground water that is in excess of the Maximum Contaminant Levels (MCLs)
at the southern boundary of Hill AFB using a series of vertical extraction wells located in
the vicinity of the South Gate area

• Discharge ground water to the North Davis County Sanitation District (NDCSD) sanitary sewer.

Statutory Determinations

This interim action is protective of human health and the environment, complies with Federal and State
applicable or relevant and appropriate reguirements for this limited scope action, and is cost-effective.
This action is interim and is not intended to utilize permanent solutions and alternative treatment (or
resource recovery) technologies to the maximum extent practicable for this operable unit. This interim
action does not provide on-site treatment; however extracted ground water will be treated at the NDCSD
sanitary sewer, which is a Publicly Owned Treatment Works (POTW) . Because this action does not constitute
the final remedy for the operable unit, the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element, although partially addressed in this
remedy, will be addressed by the final response action. Subseguent actions are planned to address fully
the threats posed by the conditions at this operable unit. Because this remedy will result in hazardous
substances remaining on site above health-based levels, a review will be conducted to ensure that the
remedy continues to provide adeguate protection of human health and the environment within five years
after commencement of the remedial action.

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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 as illustrated in Figure 1-1. Hill
AFB covers an area of 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 5,000 feet above NGVD. The Great Salt Lake, approximately 12 miles to the west,
is presently at an elevation of approximately 4,200 feet above NGVD.

Most of the southern part of Hill AFB is occupied by industrial facilities, eguipment 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 facilities has
changed in recent years to missile storage, maintenance, and testing, the building and facilities remain.
Off-Base land use in the Operable Unit (OU 8) area includes residential, commercial, and agricultural.
This area has undergone rapid residential and commercial development over the last five years and
agricultural use has declined. Crop production in this area is primarily hay and alfalfa. There is
pasture land and in some limited areas livestock are raised.

In July 1987, Hill AFB was placed on the National Priorities List (NPL) under the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) to address sites where hazardous liquid
and solid wastes generated by installation operations were disposed. These hazardous waste sites have
been divided into nine operable units (OUs) in accordance with a Federal Facility Agreement (FFA)
executed in 1991 between the U.S. Air Force (USAF), State of Utah Department of Health (now the Utah
Department of Environmental Quality [UDEQ]), and the United States Environmental Protection Agency (EPA)
Region VIII.

Operable Unit 8 is one of the newest operable units at Hill AFB following reorganization in December
1993. The reorganization was to address existing and additional potential source areas (contaminated soil
sites within OUs 3, 7, and 9) separately and to consolidate ground-water response actions beneath the
southern industrial complex. Conseguently, OU 8 comprises the ground water within a shallow aguifer
beneath the on-Base industrial area and in the Layton and Clearfield areas south of the Base. This area
is shown on Figure 1-2.

Based on the available data, most of the ground-water contamination occurs in the shallow aguifer beneath
the industrial area and in off-Base locations directly south of Hill AFB. Off-Base contamination
predominantly occurs beneath the Layton area. Although no ground-water contamination has been found in
the Clearfield area, additional investigations will be conducted to confirm that this is the case. For
the purpose of this Record of Decision (ROD) , the Layton and Clearfield areas will be referred to as the
"off-Base areas."

The shallow aguifer beneath the industrial and off-Base areas is the principal hydro-stratigraphic unit
under investigation. It consists of up to approximately 200 feet of sand interbedded with silt and clay
and lies at approximately 65 to 200 feet below the ground surface (bgs) on-Base, and about 1 to 50 feet
bgs in off-Base areas. The shallow aguifer overlies two deeper aguifers (Sunset and Delta aguifers) and
is separated from them by a thick sequence (over 100 feet) of low-permeability silts and clay (Feth et
al, 1966) .

The shallow aquifer could be (but has not been) classified as Class II - Drinking Water Quality based on
the State of Utah classification criteria and the observed quality of ground water from uncontaminated
wells in the vicinity. However, low yield private wells in the shallow aquifer within the plume area are
not used for domestic purposes. This was confirmed by a comprehensive water user survey conducted in the
Layton area of OU 8 by Hill AFB (Montgomery Watson, 1996a).

The Sunset and Delta aquifers are approximately 300 and 600 feet bgs at OU 8, respectively. These
aquifers serve as a source of domestic water supply for Hill AFB and surrounding communities and are
classified as Class I - Irreplaceable Source of Drinking Water or Class IIA - Current Source of Drinking
Water (USGS, 1992).

According to the Environmental Assessment for OU 8 (Montgomery Watson, 1994a) , several wetlands have been
identified, including Ponds 1 and 3 along the southern Base boundary, areas along the Davis-Weber canal,
and several small areas south of the canal in the city of Layton. These wetlands are not known to be
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impacted by contamination at OU 8.

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 II, the Ogden Arsenal manufactured ammunition and
was a distribution center for motorized eguipment, 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 in the OU 8 area 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 Wastewater Treatment Plant (IWTP), in chemical disposal pits and landfills, and
off-Base. Disposal in chemical pits and landfills was discontinued by 1980. All waste products are
currently treated at the IWTP, recycled on-Base, or sent to off-Base treatment or disposal facilities.

2.2 INVESTIGATION HISTORY

Investigations conducted in the OU 8 area include early investigations of OU 3, OU 7, and the UST sites.
Further details can be found in the Final Data Summary and Recommendation Report for OU 8 (DSRR;
Montgomery Watson, 1995A). As investigation data became available, the apparent extent of ground-water
contamination in on- and off-Base areas was greater than originally expected. Because of this, Hill
AFB, EPA, and UDEQ agreed that further ground-water investigation and/or potential remediation efforts in
the general area would be best facilitated by forming a separate operable unit (OU8).

Operable Unit 8 (Figure 1-2) is comprised of ground water underlying the southern industrial area of the
Base and areas immediately south of the Base. Contaminated ground water occurs in on-Base and in off-Base
areas. Some of the sources which likely contributed to ground-water contamination within the Base have
been identified, such as the soils at Operable Units 3 and 7, as well as several underground storage tank
(UST) sites (Figure 2-1). Other facilities in the southern industrial complex are in the early stages of
investigation as part of Operable Unit 9. The contribution of the Operable Unit 9 sites are not fully
understood at this time.

Hill AFB is presently conducting ground-water monitoring at OU 8. The results of the first and second
round of ground-water monitoring are presented in the Final First and Second Monitoring Rounds Data
Evaluation Report for OU 8 (Montgomery Watson, 1995d) . More recent efforts have focused on delineating
the contaminant plume and defining aquifer characteristics along the southern Base boundary.
Investigations have included cone penetrometer testing (CPT) and hydropunch sampling in which water
samples are collected directly through CPT rods (this sampling technique is similar to the Hydropunch
procedure and will be referred to as "hydropunch" for consistency with other OU 8 documentation);
installing and sampling monitoring wells; installing extraction wells and piezometers; and conducting
three constant pumping rate aquifer tests. The results of these activities are summarized in the Interim
Remedial Action Field Work Data Summary and Remedial Design Technical Memorandum for OU 8 (IRA Tech Memo;
Montgomery Watson, 1996b). Additional work associated with the OU 8 Remedial Investigation (RI) is
ongoing.

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 Agreements (FFA) between the U.S. Air Force (USAF), the State of
Utah Department of Health (now the UDEQ) , and the EPA. The purpose of the agreement was to establish a
procedural framework and schedule for developing, implementing, and monitoring appropriate response
actions at Hill AFB in accordance with existing regulations. Seven operable units were initially defined
under the FFA and two more operable units (OUs 8 and 9) have since been added. This Record of Decision
(ROD) is for an interim remedial action for OU 8 that will be performed along the southern boundary of
the Base in the vicinity of the South Gate. There have been no removal actions, notices of violation, or
other enforcement actions taken at OU 8 prior to this ROD.
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2.4 HIGHLIGHTS OF COMMUNITY PARTICIPATION

The public participation requirements of CERCLA Section 113(k) (2) (B) (i-v) and Section 117 have been met
for OU 8. Hill AFB has a Community Relations Plan that was completed in February 1992. The community
relations activities include: (1) a Restoration Advisory Board (RAB) which meets at least quarterly and
includes community representatives from adjacent counties and towns, (2) a mailinq list for interested
parties in the community, (3) a quarterly newsletter called "EnviroNews," (4) visits to nearby schools to
discuss environmental issues, (5) community involvement in a noise abatement proqram, (6) semi-annual
town council meetinqs, (7) opportunities for public comment on remedial actions, (8) community
interviews, and (9) support for the community for obtaininq technical assistance qrants (TAGs).

The Interim Remedial Action (IRA) Focused Feasibility Study (FS) for the Base Boundary, Operable Unit 8
(Focused FS; Montqomery Watson, 1995b) and the Proposed Plan for an Interim Action at Operable Unit 8
(Montqomery Watson, 1995c) were released to the public and are available in the Administrative Record
maintained in the Davis County Library and at the Environmental Manaqement Directorate at Hill AFB.
The notices of availability for these documents were published in the Salt Lake Tribune, Oqden Standard
Examiner, and Hilltop Times. A public comment period was held from Auqust 8, 1995, throuqh September 7,
1995, and a public Open House was held on Auqust 17, 1995. At this meetinq, representatives from Hill
AFB, EPA, and the UDEQ answered questions about the site and the selected remedy. Copies of all written
transcripts and verbal public comments received at that Open House are presented in the Responsiveness
Summary of this document for inclusion in the Administrative Record (also see Appendices A and B). The
decision for this site is based on the Administrative Record.

2.5 SCOPE AND ROLE OF OPERABLE UNIT 8 WITHIN SITE STRATEGY

Operable Unit 8 is one of nine operable units at Hill AFB and is in the early staqes of the RI/FS
process. The remaininq operable units are at various staqes in the CERCLA process. The remedial actions
planned for the various operable units are independent of one another. This interim remedial action
addresses contaminated qround water alonq the southern boundary of Hill AFB. The interim remedy selected
for OU 8 addresses future threats to human health and the environment by preventinq qround-water
transport of contaminants to off-Base areas, thereby controllinq the volume and areal extent of
contamination and reducinq future potential off-Base risk and cleanup costs. The interim remedy selected
for OU 8 would contain the miqration of contaminants at the southern boundary of Hill AFB by removinq
qround water with a series of vertical extraction wells.

3.0 SUMMARY OF SITE CHARACTERISTICS

3.1 HYDROGEOLOGIC SETTING

The shallow aquifer at OU 8 qenerally, consists of sand interbedded with silt and clay. Because of
lateral discontinuities and the interbedded nature of the sand, silt, and clay layers, qround water
occurrinq in the deeper units of the shallow aquifer is hydraulically connected to the shallower qround
water in the overlyinq units. The interbedded sand units, which have a hiqher hydraulic conductivity than
the surroundinq clay and silt units, may provide preferential flow paths for qround-water and contaminant
transport. Because the sediments underlyinq OU 8 were deposited in a deltaic environment, these
interbedded sand units probably represent distributary channels of the main ancestral Weber River. If so,
they may extend for fairly lonq distances as discrete units within the finer-qrained sediments.
Consequently, they may provide preferential pathways for transport of qround-water contaminants to
off-Base areas. The heteroqeneous nature of the aquifer results in tortuous qround-water flow and
contaminant transport paths, leadinq to irreqularly shaped contaminant plumes.

The interbedded nature of the aquifer may also result in the development of locally confined (i.e.,
artesian) conditions or perched qround water. Localized zones of perched qround water underlie the IWTP
Sludqe Dryinq Beds (based on the results of the OU 3 Phase I and II RI studies).

Ground-water recharqe of the shallow aquifer at OU 8 is probably from infiltration of precipitation at OU
8 and from qround-water throuqh flow from the east. The qroundwater throuqh flow probably oriqinates from
infiltration of precipitation in the topoqraphically hiqh areas east of OU 8. Based on qround-water
elevation contours (shown on Fiqure 3-1), Ponds 1 and 3 appear to be siqnificant local sources of
recharqe to the shallow aquifer beneath OU 8. Discharqe of qround water from the shallow aquifer at OU 8
probably occurs via seeps, sprinqs, field drains, streams, low yield private wells (not used for domestic
purposes), and evapotranspiration to the south in the cities of Layton and Clearfield.

As of February 1997, qround water beneath OU 8 occurred at depths ranqinq from 3 feet below qround
surface (bqs) in several wells in the off-Base area to 173 feet bqs north of the west ramp area of the
388th Fiqhter Winq (i.e. northern most portions of the OU 8 contaminant plume, as illustrated in Fiqure
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3-2). Based on ground-water elevation contours illustrated in Figure 3-1, shallow ground water underlying
the industrial area is flowing to the west and northwest. Shallow ground water underlying the Herman Pond
and Pond 1 areas flows to the northwest, west, and southwest. Shallow ground water beneath Pond 3 flows
away from the pond, particularly to the southwest. Based on the configuration of the ground-water
surface, both Pond 1 and Pond 3 appear to recharge the shallow aguifer, influencing the shallow
ground-water flow system, by creating ground-water divides near both ponds. Ground water on one side of
the divide created by Pond 1 flows northwest, while ground water on the other side flows to the
southwest. Near Pond 3, ground water east and north of Pond 3 flows northeast, eventually changing to a
north-northwesterly flow near the OU 7 sites in the industrial area. Ground water south of Pond 3 flows
essentially to the southwest. The ground-water surface in the Layton area reflects the ground surface
topography, with the horizontal hydraulic gradient essentially to the southwest.

Horizontal Hydraulic Conductivity. Horizontal hydraulic conductivity values for the shallow aguifer were
calculated based on constant rate aguifer tests conducted in 3 extraction wells along the southern Base
boundary. These 3 wells will be included as part of the IRA system. The hydraulic conductivity ranged
from 3 feet/day (1 x 10 -3 cm/sec) to 38 feet/day (1.3 x 10 -2 cm/sec) in these wells. These values of
the hydraulic conductivity for the shallow aguifer are typical of published values for clean sands, silty
sands, and silts.

Vertical Hydraulic Conductivity. Vertical hydraulic conductivity values were calculated using
falling-head permeameter tests for 69 undisturbed soil samples. These data are summarized in the DSRR
(Montgomery Watson, 1995a). The vertical hydraulic conductivity values range from 26 feet/day (9 x 10 -3
cm/sec) to 1.1 x 10 -4 feet/day (4 x 10 -8 cm/sec). The permeability tests show that the vertical
hydraulic conductivity values are generally directly proportional with grain size. For example, the
maximum vertical hydraulic conductivity was measured in a clean sand (SP), while the minimum vertical
hydraulic conductivity was measured in a silty clay (CL) and clayey silt (ML). Vertical hydraulic
conductivities are generally one to two orders of magnitude less than the horizontal hydraulic
conductivities.

Vertical Hydraulic Gradients. Estimates of vertical hydraulic gradients for ground water in the shallow
aguifer were calculated using ground-water piezometric surface elevations from monitoring well pairs that
were close to each other and that were screened at different depths. The vertical hydraulic gradients
were calculated for each well pair by dividing the difference in hydraulic head measured in the two wells
by the vertical distance in feet between the centers of the screened intervals of the wells. The
calculated values of the vertical hydraulic gradient for the five well pairs in the vicinity of South
Gate ranged from 0.3 to -0.1 (negative sign indicates upward vertical gradient). Downward gradients exist
at four of the five locations in the shallow aguifer at OU 8.

3.2 OU 8 SOURCE AREAS

The results of the studies associated with OU 3, OU 7, OU 9 and USTs have led to the identification and
investigation of potential contaminant source areas within OU 8. Based on these investigations, several
historical waste management areas have been identified as sources for volatile organic contaminants
(VOCs) and inorganic compounds within OU 8 ground water, and other potential VOC sources may exist that
have not yet been identified. The following source areas have likely impacted ground water at OU 8:
Buildings 200 and 225 (OU 7); Berman Pond, the IWTP Sludge Drying Beds, the RVMF and Pond 1 (OU 3); and
the UST Sites 260 and 280. Pond 2, which is located off Base (Figure 3-2), may also have impacted OU 8
ground water. The DSRR (Montgomery Watson, 1995a) discusses these sites in detail.

3.3 NATURE AND EXTENT OF CONTAMINATION

The following discussion of ground-water contaminants at OU 8 focuses on the contaminants detected
beneath the southern boundary of Hill AFB which is in the vicinity of where this interim action will be
implemented. Table 3-1 presents a summary of the concentration ranges of volatile organic compounds
(VOCs) detected in samples collected from ground-water monitoring wells near the Base boundary. As
indicated on Table 3-1, several types of VOCs were detected in ground water at OU 8. The most common and
widespread of these compounds is trichloroethene (TCE). For comparison, Federal and State of Utah
drinking water standards are presented in the right column of Table 3-1. The area within OU 8 where
contaminants in ground water exceed Federal and the State of Utah drinking water standards is shown on
Figure 3-2. The area of known contamination in excess of these standards extends from the north end of
the industrial complex south to the southern Base boundary. In off-Base areas, several areas with VOC
contaminants have been identified. Based on data presented in the IRA Tech Memo (Montgomery Watson,
1996b), VOC contamination above the MCL at the Base boundary is limited to a maximum depth of 140 feet
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bgs. No metals contamination has been detected at the Base boundary. Maximum contaminant concentrations
occurring in on-Base ground water at OU 8 are also presented on Table 3-1. Contaminant concentrations are
generally lower in off-Base areas. The source or sources of the off-Base contamination are being
investigated. Refer to the DSRR (Montgomery Watson, 1995a) for a detailed description of VOC
contamination in OU 8 ground water.

Figure 3-3 illustrates the horizontal and vertical distribution of contaminants at the Base boundary. The
analytical results from hydropunch samples may not be guantitatively comparable to results from
monitoring/extraction well samples. However, hydropunch samples are considered screening samples, and are
distinguished from monitoring/extraction well samples on Figure 3-3.

Figure 3-3 shows that contaminants were detected along the southern Base boundary above MCLs in
Monitoring Well U3-031 east of South Gate Drive, near Extraction Well U8-201, and in Monitoring Wells
U8-024, U3-043 and U8-051 west of South Gate Drive near Extraction Wells U8-202 and U8-203. Contaminants
were detected above MCLs from the water table to a maximum depth of 140 feet bgs (in Monitoring Well
U8-024). The vertical contaminant distribution along the southern Base boundary appears to be
lithologically controlled and largely is restricted to the sand unit. Except for the Monitoring Well
U8-024, contaminants have not been detected in greater than trace concentrations in the clay unit.

The compound detected most commonly at the highest concentrations in the ground water at the Base
boundary is trichloroethene (TCE) , which was detected at a maximum concentration of 88 micrograms per
liter (Ig/1) in the Monitoring Well U8-024 sample. Figure 3-3 depicts the zones in the ground water along
the Base boundary where any contaminant was detected at a concentration greater than its MCL.

Contaminants detected at levels above MCLs are restricted to a zone approximately 200 feet wide near
Extraction Well U8-201 and a zone approximately 600 feet wide near Extraction Wells U8-202 and U8-203.
Contaminant concentrations are generally higher west of South Gate Drive and extend to approximately 140
feet bgs.

The historical source of contamination in the shallow aguifer near the Base boundary at OU 8 is Berman
Pond. However, due to changes in the hydraulic regime at OU 8, this contamination is likely residual. In
the past, while Berman Pond was in use as an industrial wastewater and stormwater retention pond, it
caused mounding in the water table beneath the pond and drove contaminated ground water to the south and
southwest toward the Base boundary. After the use of Berman Pond was discontinued in 1956 and the pond
was subseguently capped in the 1970s, the ground-water flow regime assumed the current configuration
shown in Figure 3-1. Ground-water mounding associated with Ponds 1 and 3 began to have a stronger
influence on ground-water flow near the Base boundary. It now appears that ground-water flow in the
general area may at least partially divert residual Berman Pond contaminants north away from the Base
boundary toward the interior of the Base. A portion of the contaminants from Berman Pond immediately
along the southern Base boundary may also be migrating to the west and ultimately to the south-southwest
(off-Base).

3.4 CONCEPTUAL MODEL OF CONTAMINANT TRANSPORT

A conceptual model of contaminant migration, shown in Figure 3-4, has been developed for OU 8. The model
was based on the site physical characteristics and on the nature and extent of contamination observed at
OU 8 to date. The conceptual model is summarized below. Section 4.0 of the DSRR (Montgomery Watson,
1995a) details the development of this model.

In the area designated for the interim remedial action, the migration route of contaminants is
principally through the zones of higher permeability within the shallow aguifer. At the southern Base
boundary, the water table occurs at depths of approximately 65 to 80 feet bgs and the aguifer consists of
layers of sand and silty sand, interbedded with silt and clay. At approximately 100 to 110 feet bgs a
fine-grained unit of silt and clay is present. At locations to the west of South Gate Drive this
fine-grained unit does not occur until 180 to 190 feet bgs.
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TABIiE 3-1
CONTAMINANTS DETECTED ON BASE IN OU 8 GROUND WATER
Compound

Trichloroethene (TCE)

1,1,1-Trichloroethane (1,1,1-TCA)

Tetrachloroethene (PCE)

1,2-Dichloroethane (1,2-DCA)

1,1-Dichloroethene (1,1-DCE)

Benzene

Chlorobenzene

Arsenic

Total Chromium

Hexavalent Chromium
Max. Chemical
Concentrations in
OU 8 Ground
Water (On-Base)
(Ig/D
Max. Chemical
Concentrations in
Ground Water
Beneath Southern
Base Boundary a
(Ig/D
Utah and Federal
Standards for
Drinking Water
(Ig/1)
2,000
1,200
130
480
190
23.9
370
147
3,460
2,130
88
3
6
480 (b)
1
1
14
ND
ND
ND
5
200
5
5
7
5
100
50
50
50
Ig/L Micrograms per liter
ND Not detected

Only those contaminants that exceed Utah or Federal standards for drinking water are shown on this table.

(a) Analytical results included in this column are from monitoring wells U8-024, U8-047, U8-048,
U8-051, U3-031, and U3-043, (see Figure 2-1 for the locations of these wells).

(b) 1,2-DCA has not consistently been detected. 1,2-DCA was detected in Monitoring Well U8-024
at concentrations of 480 Ig/L and 270 Ig/L in February 1995 and July 1996, respectively, but was
not detected (<5 Ig/L) in July 1995.

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Past waste handling practices at Herman Pond allowed contaminants to enter soil and surface water which
eventually migrated downward to the shallow ground water. After entering the shallow ground-water system,
contaminants (principally TCE) were transported downward into the aguifer and to the southwest toward the
Base boundary. Recent sampling results indicate that VOC contaminants (above MCLs) have migrated downward
to a depth of approximately 140 feet bgs on the west side of South Gate Drive at the southern Base
boundary. Several hundred feet of low permeability sediments separate the shallow aguifer from the
deeper, drinking water aguifers (i.e., the Sunset and Delta aguifers). These low permeability sediments
have and should continue to significantly impede deeper transport of contaminants from OU 8 to the
drinking water aguifers. Ground-water flow directions in the shallow aguifer indicate that dissolved
contaminants are moving from the southern Base boundary toward off-Base areas in a south-southwest
direction. These contaminants are transported by shallow ground water in this direction. Some of this
water is intercepted by one or more of the numerous field drains south of the Base (see Figure 2-1). Once
the contaminants enter the field drain system, the transport rate is greatly accelerated.

4.0 PUBLIC HEALTH AND ENVIRONMENTAL IMPACTS

This section presents a brief and gualitative description of the potential risks associated with ground
water at OU 8, particularly contaminated ground water at the southern Base boundary. A gualitative risk
assessment was performed because the OU 8 investigation is in the early RI stage and information is not
currently available for a full baseline risk assessment. A baseline risk assessment for the entire
Operable Unit will be conducted as part of the upcoming RI for OU 8.

4.1 HUMAN HEALTH RISKS

Based on the conceptual model of contaminant transport, the potentially significant pathways of human or
environmental exposure to contaminants at OU 8 under current and future conditions include exposure to
shallow off-Base ground water. Figure 4-1 depicts the potential exposure pathways to VOC contaminants
that are present at OU 8, both on and off-Base. As shown in Figure 4-1, there is no current potential for
exposure and only low to negligible future potential for exposure (based on the combination of the
likelihood of pathway completion and the magnitude of exposure if a pathway is completed) associated with
contaminated ground water on Base, including ground water at the southern Base boundary. While there is a
low potential for pathway completion, there could be significant risks if people were to use the shallow
aguifer as their drinking water supply. If contaminated ground water is transported to the off-Base area,
current and future (i.e., the near future where contaminated ground water could be used as drinking
water) off-Base ground-water users could be exposed to contaminants present in the ground water. As shown
in Figure 4-1, off-Base receptors include farmers or landowners who may use or drink contaminated ground
water collected in off-Base field drains. Based on a ground-water users survey, all of these potential
receptors are connected to municipal water, but some still use ground water collected from field drains
for livestock watering and irrigation (Montgomery Watson, 1996b). The potential for use of the water as
tap water is considered higher off-Base than on-Base because Hill AFB controls its on-Base water usage.
Current and future ecological receptors also may be exposed to contaminated ground water discharging from
field drains.

4.2 ENVIRONMENTAL RISK

Air Quality. The VOC emissions from shallow on-Base ground water to the air are not expected to be
significant due to the depth of this ground water. VOC emissions from field drains are also not expected
to have a significant impact due to their low concentrations.

Surface Water, Ground Water, and Wetlands. No streams, rivers, or lakes exist on Hill AFB. The shallow
aguifer is about 65 to 200 feet bgs on-Base and 10 to 50 feet bgs off-Base. This aguifer has been
impacted, and is the subject of the proposed interim action. The shallow aguifer is separated by several
hundred feet of silts and clays from deeper aguifers. There is no evidence that the deeper aguifers have
been affected by VOCs. Numerous wetlands have been identified on Hill AFB and in the surrounding
communities. Several of these are within the boundaries of OU 8. Water guality of some of these wetlands
in the Layton area may have been impacted. However, by implementing this proposed interim action, the
spread of contamination into this area will be reduced and the net effect will be an improvement of the
existing water guality.

Vegetation. All areas of OU 8 are highly modified and do not contain any threatened or endangered plant
species. No adverse effects on the local ecosystem are anticipated.

-------
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 or the off-Base area. Operable Unit 8 and
the surrounding areas are developed, and the proposed interim remedial activities and additional human
presence will add no significant impact to wildlife.

Archaeological Resources. There are no known cultural or archaeological resources on Hill AFB or in the
off-Base area in the vicinity of OU 8.

5.0 DESCRIPTION OF INTERIM REMEDIAL ACTION ALTERNATIVES

As part of the Focused FS for OU 8 (Montgomery Watson, 1995b) , five specific interim remedial action
alternatives were developed for ground-water containment to meet the interim remedial action objectives
(RAOs). Under Section 121 of CERCLA, a selected interim remedial action must be protective of human
health and the environment, and must comply with (or waive) applicable or relevant and appropriate
reguirements (ARARs). This interim action is to prevent further environmental degradation. ARARs within
that scope have been evaluated. ARARs pertaining to restoration alternatives will be evaluated for the
final remedy or remedies. The alternatives were then 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. Then the alternatives were compared against
these criteria for selecting the recommended remedial measure alternative. Additionally, State and
community acceptance must be considered before a remedy is selected. This section summarizes how the
remedy selection process for OU 8 addressed these reguirements.

5.1 DEVELOPMENT OF ALTERNATIVES

Interim remedial alternatives were developed by assembling technologies into combinations that are
applicable for the medium of concern at OU 8 (ground water). The steps that were used to develop remedial
alternatives for OU 8 included development of response objectives, remedial action objectives, and
general response actions for contaminated ground water, followed by a preliminary screening and
evaluation of technologies and process options. Response objectives include prevention of human exposure
to contaminated ground water through direct contact or ingestion, and enabling long-term attainment of
shallow ground-water remedial action objectives. Remedial action objectives (RAOs) were developed to
define the extent of the interim remedial action. Based on the current understanding of the nature and
extent of contamination, exposure pathways, and potential risks associated with OU 8, the following RAOs
were established for an interim remedial action at OU 8:

• Contain ground water at the southern boundary of Hill AFB to prevent off-Base transport of
contaminants in excess of MCLs in the shallow ground water and reduce future potential
off-Base risks

• Reduce the spread of contaminants, thereby controlling the volume and areal extent of
contaminated ground water at OU 8

• Reduce future cleanup costs by controlling the spread of contamination.

General response actions identify basic actions that might be undertaken as part of an interim 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 Focused FS (Montgomery Watson, 1995b).

The technologies and process options that passed the screening criteria were assembled into four
alternatives. As reguired by the NCP process, the "No Action" alternative was retained for the purpose of
comparison.

5.2 DETAILED ANALYSIS OF ALTERNATIVES

Each alternative for this interim action uses hydraulic containment as the primary element with different
processes for ground-water treatment and disposal.

During the detailed analysis of alternatives for OU 8, each alternative was assessed against nine
evaluation criteria defined in the NCP 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 adeguately compare the alternatives, select an appropriate interim remedial action, and
satisfy CERCLA remedy selection reguirements. The detailed analysis of alternatives included developing
-------
and further defining the volumes or areas of contaminated ground water to he addressed, the technologies
to be used, and the performance reguirements associated with those technologies. Also included in the
Focused FS is an assessment and summary profile of each alternative and a comparative analysis among the
alternatives.

Alternative 1: No Action

The No Action Alternative involves taking no action until the final remedy for OU 8 is implemented. This
alternative is included as a basis of comparison with other alternatives. As is common to all the
alternatives, periodic monitoring of ground water is included. Ground-water monitoring would include
testing the ground-water guality both upgradient and downgradient of the Base boundary in 10 monitoring
wells. There are no capital cost reguirements for Alternative 1, but the annual operating and maintenance
cost is $74,000. The estimated six-year present-worth cost is $330,000.

Alternative 2: Ground-Water Extraction, Treatment with Carbon Adsorption, Discharge to Storm Drain

Alternative 2 includes the following technologies:

• Ground-water extraction with vertical wells

• Ground-water treatment using carbon adsorption technology to reduce contaminants in the
water to acceptable levels

• Discharge of treated water to a storm drain

• Transport the used carbon containing potential hazardous waste to an off-Base facility.

Under this alternative, vertical extraction wells drilled along a 1,200-foot wide area along the southern
Base boundary (see Figure 5-1) would supply contaminated ground water to an above-ground carbon
adsorption system for treatment. Treated ground water would then be discharged to the storm drain. A
ground-water monitoring program like that described for Alternative 1 would be conducted as part of this
alternative. In addition, the monitoring program would be used to monitor system performance. Performance
would be evaluated with respect to current concentrations as a baseline. If contaminant concentrations
downgradient of the extraction system decrease with time, the system would be considered to be performing
as designed. However, if contaminant concentrations increase downgradient during system operation, the
system would need to be reevaluated.

This alternative would contain ground water along a 1,200-foot long section at the southern Base boundary
to depths of approximately 140 feet bgs. This alternative would also meet the objectives of the IRA by
containing ground water on Base and preventing it from migrating to off-Base areas and further impacting
human health and the environment. No treatability studies are planned for any of the alternatives in this
interim action. Operational information gathered during the duration of this IRA would be evaluated with
regard to effectiveness as to its potential to be used as part of the final remedy. Alternative 2 would
be easy to implement from a technical and administrative standpoint. However, installation of the
extraction system and conveyance piping would traverse beneath the south entrance to Hill AFB, which
would reguire coordination with Base Civil Engineering. Off-Base transportation of spent carbon for
regeneration and reuse would reguire manifesting and possibly a modification of the existing State-issued
permit for Hill AFB under RCRA.

Capital cost reguirements for Alternative 2 are $1,041,000, and the annual operating and maintenance cost
is $114,000. The estimated six-year present-worth cost is $1,552,000.

Alternative 3: Ground-Water Extraction, Treatment with Air Stripping, Discharge to Storm Drain

Alternative 3 includes the following technologies:

• Ground-water extraction with vertical wells

• Ground-water treatment using an air stripper to reduce contaminants in the water to
acceptable levels

• Discharge of treated water to a storm drain.

-------
Under this alternative, the extraction wells (as described in Alternative 2) would discharge contaminated
ground water to an above-ground air stripping system for treatment. Treated ground water would then be
discharged to the storm drain. A ground-water monitoring and compliance program like that described for
Alternative 2 would be conducted as part of this alternative.

The SCREEN2 Model was used to estimate air emissions from the treatment system at the Base boundary. In
accordance with the UDEQ toxicity screening procedure, the contaminant concentrations in air at the
nearest receptor were evaluated. Due to the proximity of the OU 8 interim action to the Base boundary,
the nearest receptor point was assumed to be at that boundary. Potential receptors that were considered
included: on-Base personnel, residential neighborhoods, and commercial developments. Preliminary modeling
results suggest that emissions from the air stripper would be well below the UDEQ requirements, and that
no air pollution control device would be necessary for the air stripper off-gas. However, the UDEQ would
need to be notified before operating the air stripper.

This alternative would have similar containment and implementability requirements as described for
Alternative 2. Capital cost requirements for Alternative 3 are $989,000, and the annual operation and
maintenance cost is $110,000. The estimated six-year present-worth cost is $1,481,000.

Alternative 4: Ground-Water Extraction and Discharge to Sanitary Sewer

Alternative 4 includes the following technologies:

• Ground-water extraction with vertical wells

• Discharge of extracted ground water to sanitary sewer.

Under this alternative, extracted ground water would be discharged directly to a sanitary sewer. Previous
monitoring results indicate that the volatile organic contaminants are present primarily around Berman
Pond and monitoring well U3-025 (Figure 3-1). Since the proposed extraction system would be located at
the southern edge of the plume, the extracted ground water would contain dilute concentrations of VOCs.
No ex-situ treatment would be required to meet the discharge limits (primarily the total toxic organics
limit of 2.04 mg/1) established by the North Davis County Sanitation District (NDCSD). This alternative
would also include the ground-water monitoring and performance program described for Alternative 2.

As with Alternative 3, this alternative would have similar containment and implementability requirements
as described for Alternative 2. Capital cost requirements for Alternative 4 are $775,000, and the annual
operating and maintenance cost is $136,000. The estimated six-year present-worth cost is $1,385,000.

Alternative 5: Ground-Water Extraction, Treatment at IWTP, Discharge to Sanitary Sewer

Alternative 5 includes:

• Ground-water extraction with vertical wells

• Conveyance of extracted ground water to the IWTP for treatment

• Discharge of treated ground water to the sanitary sewer.

Under this alternative, contaminated ground water would be extracted and discharged to an on-Base
industrial wastewater pipeline and transported to the IWTP. At the IWTP, extracted ground water would be
treated through an existing, above-ground air stripper. Treated water would be discharged to a sanitary
sewer through an existing connection. Air quality and local discharge limits would be met under existing
permits for the IWTP. This alternative would also include the same ground-water monitoring and
performance program described for Alternative 2. The treatment components presented as part of this
alternative have been slightly modified from what was reported in the Focused FS (Montgomery Watson,
1995b). The modification includes eliminating carbon treatment of air emissions, which is consistent with
the current permitted operation at the IWPT.

This alternative would have similar containment and implementability requirements as described for
Alternative 2. Capital cost requirements for Alternative 5 are $776,000, and the annual operating and
maintenance cost is $223,000. The estimated six-year present-worth cost is $1,764,000.

5.3 COMPARATIVE ANALYSIS OF ALTERNATIVES

Each of the five alternatives described above was evaluated against nine evaluation criteria to assess
their relative advantages and disadvantages, and to identify key tradeoffs that were balanced in
-------
selecting an interim action alternative for ground-water containment. Based on this comparison, a
preferred alternative was selected for an interim action at OU 8.

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
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 adeguate protection of human health and the environment.

2. Compliance with ARARs describes whether the alternative complies with ARARs or, if a waiver is
reguired, how it is justified. Other information from advisories, criteria, and the guidance "to be
considered" is also addressed.

Only those ARARs within the scope of this interim action are evaluated in this ROD. Compliance with
ARARs for the entire site will be discussed in the feasibility study (FS) for OU 8. Additionally,
the final action for OU 8 also will be developed during the FS process.

Balancing Criteria

The five balancing criteria form the basis of the comparative analysis because they allow tradeoffs among
the alternatives reguiring different degrees of performance.

3. 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.

4. 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.

5. Reduction of Toxicity, Mobility, and Volume (TMV) Through Treatment refers to the preference for
treatment technologies that meet this criterion at the site.

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 are expected to provide accuracy of plus 50 percent to minus 30 percent for a
six-year period. The six-year period is used as a common point of comparison for evaluating the
interim action alternatives (i.e., the time until a final OU 8 remedy is implemented). Cost can only
be a deciding factor for alternatives that are egually protective of human health and the
environment.

Modifying Criteria

The modifying criteria described below are generally addressed in response to comments from the State and
the public after 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 of Alternatives

In this section, the alternatives are compared to evaluate their relative performance according to each
of the evaluation criteria. The objective of the comparison is to assess the relative advantages and
-------
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 briefly discussed in the
following paragraphs.

Overall Protection of Human Health and the Environment. Implementation of ground-water containment
alternatives (i.e., Alternatives 2, 3, 4, and 5) would represent a preliminary step in achieving
long-term protection of human health and the environment. Each of these alternatives would prevent
transport of contaminants to off-Base areas. The no action alternative does not minimize transport of
contaminated ground water to off-Base areas or mitigate potential threats to human health and the
environment.

Compliance with ARARs. MCLs and State of Utah water quality standards are not ARARs because Alternatives
2 through 5 are designed as interim containment actions (not aguifer restoration actions). However, the
area of containment that will be established for each alternative will be defined by the area where
contaminant concentrations are in excess of MCLs and State of Utah water guality standards. These ARARs
will be addressed as part of the final remedy or remedies selected for OU 8. Because Alternative 1
involves no action except ground-water monitoring, the only ARARs for this alternative are ground-water
monitoring ARARs.

The potential ARARs that will be met during implementation of Alternatives 2 through 5 include chemical-
and action-specific ARARs. All ARARs that must be met for each alternative are listed in Table 5-1.

All of the alternatives are administratively feasible, but each must comply with ARARs or obtain or
revise permits pertaining to discharge of the extracted water and waste handling. In terms of discharge,
the treated water would be discharged to a storm drain (Alternatives 2 and 3) , sanitary sewer
(Alternative 4), or to an industrial sewer (which discharges to the sanitary sewer) that goes to the
publicly owned wastewater treatment plant (Alternative 5). For Alternatives 2 and 3, Hill AFB's
stormwater discharge permit would need to be revised to include the discharge from the treatment systems
for these alternatives. For Alternatives 4 and 5, Hill AFB would need to contact the North Davis County
Sanitary District (NDCSD) and obtain a permit or permit modification to discharge to the sanitary sewer.

In terms of waste handling, off-site regeneration of used carbon (Alternative 2) would reguire compliance
with hazardous waste manifesting regulations and the Federal and State Department of Transportation
hazardous materials regulations and hazardous waste generator storage requirements.

One location-specific ARAR (R315-8-2.9) is applicable to implementing the OU8 interim action. In order to
comply with this rule, it will be necessary to locate any new treatment facilities outside areas
considered to be a 100-year flood plain.

Short-Term Effectiveness. Alternatives 2 through 5 would be designed to protect workers and the community
during implementation of the remedial action. Worker protection would be consistent with OSHA
requirements in 29 CFR 1910.120, the OU 8 Health and Safety Plan, and the Contingency Plan (to be
developed) during construction and operation. The process tanks and pipelines would have secondary
containment systems with leak detection to identify and collect accidental spills or leakage. Emissions
from the air stripper (Alternatives 3 and 5) would be well below the health-risk based standards and are
not expected to pose a threat to the surrounding community or the environment. Since no action would be
taken at OU 8, Alternative 1 does not provide any short-term effectiveness.

Long-Term Effectiveness. Alternatives 2 through 5 would prevent transport of contaminants to off-Base
areas and reduce potential impact to human health and the environment. Operational information from these
interim remedial systems would be useful in evaluating the long-term effectiveness and permanence of a
final remedy. Alternative 1 delays any action until the final remedy is selected, so this alternative
would provide no long-term effectiveness nor permanence. Ground-water contamination would migrate further
off-Base, increasing the volume of contaminated ground water and the subsequent cost of the final remedy.

Reduction of Toxicitv, Mobility, and Volume Through Treatment at the Site. Alternatives 2, 3 and 5 are
expected to be equally effective in reducing the toxicity, mobility, and volume of ground-water
contaminants. The mobility of contaminants would be reduced with Alternatives 2, 3, and 5 as the ground
water is extracted; on-site treatment would reduce the volume and toxicity of contaminants. These
alternatives would be designed to minimize further migration of contaminated ground water to off-Base
areas. For Alternative 4, the ground water is discharged directly to the sanitary sewer without on-site
treatment. The mobility of contaminants would be reduced using an on-site extraction system. The toxicity
and volume of contaminants would be reduced off site as the ground water is treated at a POTW. Since
Alternative 1 does not include any treatment, this alternative would not reduce the toxicity, mobility,
or volume of contaminants at OU 8.
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TABLE 5-1
SUMMARY OF ARARs FOR EACH ALTERNATIVE
(1 of 4)
Alternative
Ap
ARARs With Which the Alternatives Comply

• R315-8-6 UAC
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
• R655-4 UAC
(Standards for drilling ard abandonment of wells)
• 40 CFR Part 264, Subpart F
(Requirements for defection and containment of releases)
• R307-1-2 UAC
(Utah Air Conservation Rules - general requirements)
• R307-1-3 UAC
(Emission standards for control of installations)
• R307-1-4 UAC
(Emission standards)
• R307-10 UAC
(Utah NESHAPs Standards)
• R307-12 UAC
(Fugitive Dst Emission Standards)
• R307-14 UAC
Emission Standards for Ozone Non-Attainment Areas, Davis and Salt
Lake Counties)
• R315-2 UAC
(General requirements - identification and listing of hazardous waste)
• R315-5 UAC Ap
(Hazardous waste generator reguirements)
• R315-8-2.9 Ap
(Standards for Owners and Operators of Hazardous Waste Treatment
Storage and Disposal Facilities; General Facility Standards; Location
Standards)
R315-8-6 UAC
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
• R317-1 UAC
(Definitions for water pollution rules and general reguirements)
• R317-2 UAC
(Standards for guality of waters of the State)
• R317-6 UAC
(Ground-water guality protection rule)
R317-8 UAC
(Utah pollution discharge elimination system)
R655-4 UAC
(Standards for drilling and abandonment of wells)
40 CFR Parts 122-125
(National pollution discharge elimination System)
40 CFR Part 261
(Identification and listing of hazardous waste)
40 CFR Part 264, Subpart F
(Reguirements for detection and containment of releases)
ARAR
Ap
Ap
R
Ap
Ap
Ap
Ap
Ap
Ap
Type
A
A
A
A
A,C
A,C
C
A
A
R
Will Alternative Meet ARAR? How Will It Comply?

Yes - Complies by providing ground-water monitoring.

Yes - Design of all monitoring wells will be in accordance to this standard.

Yes - Complies by providing ground-water monitoring.

Yes -Prohibits emission of air contaminants in sufficient guantities to cause air pollution.

Yes - Air emissions during remediation will be controlled to comply with air emissions
reguirements.
Yes - Air emissions during drilling would be controlled to comply with air emissions reguirements.
Yes -Fugitive dust emissions generated during the IRA construction activites would be controlled
to meet the established fugitive dust emission standards.
Yes -Air emissions would be controlled to comply with this rule.
Yes - Determines potential waste classification and applicability of land disposal restrictions and
other solid and hazardous waste rules.
Yes - Alternative will meet all reguirements involving off-site disposal of hazardous waste.
ARAR Applicable or relevant and appropriate reguirement
RCRA Resource Conservation and Recovery Act
Ap Applicable
TSDF Treatment, Storage, and Disposal Facility
UAC Utah Administrative Code

A
L
R
C
Ap
Ap
Ap

Ap
Ap
Action-S
Location
Relevant
Chemical
A,C
A
A,C

C
A
pecific ARAR
-Specific ARAR
Y'
Y.
Y.
i,
Y'
Y'

and Appropriate
-Specific ARAR

Yes - Aternative will be design to comply with all rules and general reguirements for storm drain
discharge.
Yes - Complies by treating ground water to water guality standards before discharge.

Yes -The Utah Ground Water Protection Rule establishes numerical clean-up levels and other
performance standards for contaminated ground water. Although no determination has been made
concerning whether this Rule is an applicable or relevant and appropriate standard at OU 8, the
standards reguired by the Ground Water Quality Protection Rule will be met by complying with
drinking water MCLs.
Yes - Complies by treating ground water to water guality standards before discharge.
Yes - Alternative will be designed so that all discharge effluent will comply with discharge permits
issued to Hill AFB.
Yes - All hazardous waste will be classified according to this ARAR.
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TABLE 5-1
SUMMARY OF ARARs FOR EACH ALTERNATIVE
(2 of 4)

Alternative ARARs With Which the Alternatives Comply ARAR Type Will Alternative Meet ARAR? How Will It Comply?

Ap A Yes -Prohibits emission of air contaminants in sufficient quantities to cause air pollution.
Storm Drain) • R3 07-1-3 UAC Ap A,C Yes - Air emissions during remediation will be controlled to comply with air emissions
(Emission standards for control of installations) requirements.
• R307-1-4 UAC Ap A,C Yes - Air emissions durinq drilling would be controlled to comply with air emissions requirements.
(Emission standards)
• R3 07-10 UAC Ap C Yes - Air emissions would be controlled to comply with this rule.
(Utah NESHAPs Standards)
• R3 07-12 UAC Ap A Yes -Fuqitive dust emissions qenerated durinq the IRA construction activities would be controlled
(Fuqitive Dust Emission Standards) to meet the established fuqitive dust emission standards.
• R3 07-14 UAC Ap A Yes -Air emissions would be controlled to comply with this rule.
Emission Standards for Ozone Non-Attainment Areas, Davis and Salt
Lake Counties)
• R315-2 UAC Ap A Yes - Determines potential waste classification and applicability of land disposal restrictions and
(General requirements - identification and listinq of hazardous waste) other solid and hazardous waste rules.
• R315-5 UAC Ap A Yes - Alternative will meet all requirements involvinq off-site handlinq and disposal of hazardous
(Hazardous waste qenerator requirements) waste.

• R315-8-2.9 Ap L
(Standards for Owners and Operators of Hazardous Waste Treatment
Storaqe and Disposal Facilities; General Facility Standards; Location
Standards)
• R315-8-6 UAC R A,C
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
• R317-1 UAC Ap C Yes - Alternative will be desiqn to comply with all rules and qeneral requirements for storm drain
(Definitions for water pollution rules and qeneral requirements) discharqe.
• R317-2 UAC Ap C Yes - Complies by treatinq qround water to water quality standards before discharqe.
(Standards for quality of waters of the State)
• R317-6 UAC A,C Yes-The Utah Ground Water Protection Rule establishes numerical clean-up levels and other
(Ground-water quality protection rule) performance standards for contaminated qround water. Althouqh no determination has been made
concerninq whether this Rule is an applicable or relevant and appropriate standard at OU 8, the
standards required by the Ground Water Quality Protection Rule will be met by complyinq with
drinkinq water MCLs.
• R317-8 UAC Ap A,C Yes - Complies by treatinq qround water to water quality standards before discharqe.
(Utah pollution discharqe elimination system)
• R655-4 UAC Ap A Yes - Desiqn of all extraction and monitorinq wells will be in accordance to this standard.
(Standards for drillinq and abandonment of wells)
• 40 CFR Part 50 Ap C Yes - Air emissions are expected to be wel below established standards.
(Primary and secondary air quality standards)
• 40 CFR Part 61 subpart A Ap C Yes - Complies because air emissions of hazardous pollutants will be below the established
(NESHAPs Standards) standards.
• 40 CFR Parts 122-125 Ap A,C Yes - Alternative will be desiqned so that all discharqe effluent will comply with discharqe permits
(National pollution discharqe elimination System) issued to Hill AFB.
• 40 CFR Part 261 Ap C Yes - All hazardous waste will be classified accordinq to this ARAR.
(Identification and listinq of hazardous waste)
• 40 CFR Part 264, Subpart F Ap A
(Requirements for detection and containment of releases)

ARAR Applicable or relevant and appropriate requirement A Action-Specific ARAR
RCRA Resource Conservation and Recovery Act L Location-Specific ARAR
Ap Applicable R Relevant and Appropriate
TSDF Treatment, Storaqe, and Disposal Facility C Chemical-Specific ARAR
UAC Utah Administrative Code
-------
TABLE 5-1
SUMMARY OF ARARs FOR EACH ALTERNATIVE
(3 of 4)
Alternative
ARARs With Which the Alternatives Comply
ARAR

R307-1-2 UAC Ap
(Utah Air Conservation Rules - general requirements)
R307-1-3 UAC Ap
(Emission standards for control of installations)
R307-1-4 UAC Ap
(Emission standards)
R307-1-4 UAC Ap
(Emission standards)
R307-10 UAC Ap
(Utah NESHAPs Standards)
R307-12 UAC Ap
(Fugitive Dust Emission Standards)
R307-14 UAC Ap
Emission Standards for Ozone Non-Attainment Areas, Davis and Salt
Lake Counties)
R315-2 UAC Ap
R315-5 UAC Ap
(Hazardous waste generator requirements)
R315-8-6 UAC R
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
R317-1 UAC Ap
(Definitions for water pollution rules and general requirements)
R317-2 UAC R
(Standards for quality of waters of the State)
R317-6 UAC Ap
(Ground-water quality protection rule)
R317-8 UAC R
(Utah pollution discharqe elimination system)
R655-4 UAC Ap
(Standards for drillinq and abandonment of wells)

40 CFR Parts 122-125 Ap
(National pollution discharqe elimination System)
40 CFR Part 264, Subpart F Ap
(Requirements for detection and containment of release)
40-CFR Part 270 Ap
(Hazardous waste permit proqram)
40 CFR Part 403 Ap
(National pretreatment standards)
Will Alternative Meet ARAR? How Will It Comply?

Yes -Prohibits emission of air contaminants in sufficient quantities to cause air pollution.

Yes - Air emissions during remediation will be controlled to comply with air emissions
requirements.
Yes - Air emissions durinq drilling would be controlled to comply with air emissions requirements.

Yes - Air emissions would be controlled to comply with this rule.

Yes -Fuqitive dust emissions qenerated durinq the IRA construction activities would be controlled
to meet the established fuqitive dust emission standards.
Yes -Air emissions would be controlled to comply with this rule.

Yes - Determines potential waste classification and applicabiility of land disposal restrictions and
other solid and hazardous waste rules.
Yes - Alternative will meet all requirements involvinq off-site disposal of hazardous waste.
Yes - Alternative will be desiqn to comply with all rules and qeneral requirements for sanitary
sewer discharqe.
Yes - Ground water will be treated at the POTW

Yes -The Utah Ground Water Protection Rule establishes numerical clean-up levels and other
performance standards for contaminated qround water. Althouqh no determination has been made
concerninq whether this Rule is an applicable or relevant and appropriate standard at OU 8, the
standards required by the Ground Water Quality Protection Rule will be met by complyinq with
drinkinq water MCLs.
Yes - Ground water will be treated at the POTW
Yes - Alternative will be desiqned so that all discharqe effluent will comply with discharqe permits
issued to Hill AFB.
Yes - Complies by providinq qround-water monitorinq.

Yes - All discharqed water contaminants will be within the standards established by this ARAR.

Yes - All remedial technoloqy units will be manaqed in accordance with this ARAR.
ARAR Applicable or relevant and appropriate requirement
RCRA Resource Conservation and Recovery Act
Ap Applicable
TSDF Treatment, Storaqe, and Disposal Facility
UAC Utah Administrative Code
A Action-Specific ARAR
L Location-Specific ARAR
R Relevant and Appropriate
C Chemical-Specific ARAR
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TABLE 5-1
SUMMARY OF ARARs FOR EACH ALTERNATIVE
(4 of 4)
Alternative

Alternative 5
(Treatment at IWTP and
Discharge to Sanitary
Sewer)
ARARs With Which the Alternatives Comply
R307-1-2 UAC
(Utah Air Conservation Rules-general reguirements)
R307-1-3 UAC
(Emission standards for control of installations)
R307-1-4 UAC
(Emission standards)
R307-10 UAC
(Utah NESHAPs Standards)
R307-12 UAC
(Fugitive Dust Emission Standards)
R307-14 UAC
Emission Standards for Ozone Non-Attainment Areas, Davis and Salt
Lake Counties)
R315-2 UAC
(General reguirements - identification and listing of hazardous
R315-5 UAC
(Hazardous waste generator reguirements)
R315-8-6 UAC
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
R317-1 UAC
(Definition of water pollution rules and general reguirements)
R317-2 UAC
(Standards for guality of waters of the State)
R317-8 UAC
(Utah pollution discharge elimination system)
R655-4 UAC
(Standards for drilling and abandonment of wells)
40 CFR Part 50
(Primary and secondary air guality standards)
40 CFR Part 61, Subpart A
(NESHAPs Standards)
40 CFR Part 261
(Identification and listing of hazardous waste)
40 CFR Part 264, Subpart F
(Reguirements for detection and containment of releases)
ARAR Applicable or relevant and appropriate reguirement
RCRA Resource Conservation and Recovery Act
Ap Applicable
TSDF Treatment, Storage, and Disposal Facility
UAC Utah Administrative Code

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R
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ARAR
Ap
Ap

Ap
Ap

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Ap

Ap
Ap
Ap
Ap
Ap

Ap
Ap
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A,C

A,C

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A

C
A,C
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C
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C
A

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Ye
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Ye
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Ye
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Action-Specific ARAR
Location
Relevant
-Specific ARAR

and Appropriate
Chemical-Specific ARAR
Will Alternative Meet ARAR? How Will It Comply?

Yes -Prohibits emission of air contaminants in sufficient guantities to cause air pollution.

Yes - Air emissions during remediation will be controlled to comply with air emissions
reguirements; emission handled under existing IWTP permit.
Yes - Air emissions during excavation would be controlled to comply with air emissions
reguirements; emission handled under exsiting IWTP permit.
Yes - Air emissions would be controlled to comply with this rule.
Yes - Determines potential waste classification and applicability of land disposal restrictions and
other solid and hazardous waste rules.
Yes - Alternative will meet all reguirements involving off-site handling and disposal of hazardous
waste.
Yes - Complies with ground-water monitoring provisions.
Yes - Ground water will be treated at the IWTP under the permit.

Yes - Ground water will be treated under the existing IWTP permit.

Yes- Ground water will be treated under the existing IWTP permit.

Yes - Design of all extraction and monitoring wells will be in accordance to this standard.

Yes - Air emissions are expected to be well below established standards; emission handled under
existing IWTP permit.
Yes - Ground water will be treated under the existing IWTP permit; emission handled under
existing IWTP permit.
Yes - All hazardous waste will be classified according to this ARAR.
-------
Implementabilitv. Alternative 1 would be the easiest to implement from a technical and administrative
standpoint as it only involves ground-water monitoring. Alternatives 2 through 5 would also be relatively
easy to implement from a technical standpoint. The necessary facilities for the ground-water extraction,
treatment, and discharge systems are commercially available, simple to construct, or already exist at
Hill AFB. However, Alternatives 4 and 5 would be simplest to construct, as only extraction wells and
discharge piping would need to be installed because the sanitary sewer (Alternative 4) and the IWTP
(Alternative 5) already exist. For Alternatives 2 and 3, new treatment systems (Carbon Adsorption-
Alternative 2; Air Stripper-Alternative 3) would need to be installed in addition to extraction wells and
discharge piping. For Alternatives 2 through 5, the ground-water extraction system and piping would have
to traverse beneath the south entrance to Hill AFB. These activities would reguire coordination with
traffic and minimizing any impact to underground utilities.

In terms of operation Alternatives 4 and 5 would be simplest to operate because both the IWTP and NDCSD
already exist, both operate under existing permits, both can easily treat the contaminant concentrations
present in OU 8 ground water, and preliminary arrangements for the discharge of treated water via a
permit modification have already been made. The treatment systems under Alternatives 2 and 3 would be
simple to operate, but would reguire more direct oversight and sampling (i.e., increased operation and
management costs) to ensure that the systems are operating properly and that contaminant concentrations
are in compliance with the discharge standards.

Alternatives 4 and 5 have an implementability advantage over Alternatives 2 and 3, because: (1) the
treatment facilities (IWTP and NDCSD) already exist and a new treatment system would not need to be
constructed; (2) Hill AFB has an existing agreement with the NDCSD for discharge to the sewer (which
would need to be modified to accept the discharge from this action); and (3) the IWTP is currently
operating and could easily treat the expected and potential contaminant concentrations in the extracted
water. Alternatives 2 and 3 are relatively low on the implementability scale as these alternatives
reguire installation of new treatment technologies and obtaining a permit for discharge to a storm drain.

Costs. Alternative 1 is the least expensive of the five alternatives with a projected present worth cost
of $330,000. Among Alternatives 2 through 5, Alternative 4 has the lowest present worth (approximately
$1,385,000) and involves the least amount of capital expenditure. Alternative 3 has the next lowest
present worth (approximately $1,481,000). The operational costs associated with Alternative 3 are less
dependent on changes in contaminant concentrations, but the capital costs are higher than for
Alternatives 4 and 5. The cost of Alternative 3 also could significantly increase if air emissions
controls are reguired in the future. Alternative 2 has slightly higher costs than Alternative 3 and has a
present worth cost of $1,552,000. However, the treatment cost for this Alternative Is directly
proportional to the mass of contaminants removed. Therefore, an increase in contaminant concentrations
could have a significant impact on treatment costs. Alternative 5 has the highest present worth of all
the alternatives ($1,764,000). However, if contaminant concentrations increased, the increase in costs
for Alternative 5 would be insignificant compared to the increase in costs associated with Alternatives
2, 3, and 4 because the IWTP is designed to treat concentrated wastes. Additionally, Hill AFB believes
that the costs associated with Alternative 5 are more certain and that Hill AFB can more easily control
these costs than for Alternatives 2. 3, and 4.

State Acceptance. The State of Utah agrees with the preferred alternative (Alternative 4).

Community Acceptance. All guestions and concerns raised by the public were received during an Open House
on August 17, 1995. Alternative 5, with discharge to the IWTP was presented as the preferred alternative.
The primary concerns were related to health effects of TCE and possible exposures, such as through wells,
water in basement sumps, and standing "wet areas" in Layton. Hill AFB's responses are summarized in the
Responsiveness Summary.

The public, in general, offered no opposition to the preferred alternative. However, one community member
expressed concerns over the cost-effectiveness of using the IWTP. He expressed a preference for direct
discharge to the sanitary sewer if it was available (Alternative 4). Based on this, and additional
information discussed in Section 6.3, Hill AFB has reconsidered alternatives and is selecting Alternative
4 for the remedy for interim action at OU 8.

6.0 SELECTED REMEDY

6.1 DESCRIPTION OF THE SELECTED REMEDY

The selected remedy for an interim remedial action at Hill AFB OU 8 is Alternative 4 - ground-water
extraction and discharge to the sanitary sewer. Alternative 4 consists of ground-water extraction using 8
vertical wells, and conveyance of extracted ground water to the sanitary sewer and treatment at the POTW.
If greater treatment efficiency, or ease of implementability and cost effectiveness can be established at
-------
a later date, discharge of extracted groundwater to the IWTP (Alternative 5) may again be considered.

Figure 6-1 shows the schedule for implementing the selected remedy. The first activities will include
design of the extraction wells and ground-water conveyance systems. The design activities will be
followed by the system construction and installation. Once the system installation is complete, the
individual components of the system and then the entire system will be tested to ensure that the intent
of the design was met during the construction, and that the installed system is capable of meeting the
performance objectives. System testing will be followed by a start-up and prove-out period. The entire
system will then be operated and maintained until the final remedy is implemented. Ground-water guality
monitoring is scheduled on a guarterly basis during the initial stage of the interim remedial action
system. Ground-water monitoring will continue for the duration of the interim remedial action, but the
freguency of monitoring may be reduced based on the observed trends in contaminant concentrations or
migration. During this interim action, the system performance will be reviewed to evaluate the
effectiveness of the system and to determine if it will be used as part of the final remedy at OU 8.

6.1.1. Remediation Objectives and Performance Standards

The interim action goals and objectives for OU 8 are to:

• Contain ground water at the southern boundary of Hill AFB to prevent off-Base transport of
contaminants above MCLs in the shallow ground water and to reduce future potential off-Base
risks

• Reduce the spread of contaminants, thereby controlling the volume and a real extent of
contaminated ground water at OU 8

• Reduce future cleanup costs by controlling the spread of contamination.

The area of attainment over which these cleanup goals are to be achieved is defined as the area where
ground-water contaminants exceed MCLs in a 600-foot wide section on the west side of Hill Field Road and
a 200-foot wide section on the east side of Hill Field Road in the shallow aguifer along the southern
boundary of the Base, as shown in Figure 5-1. The extraction well design for the interim remedial action
will be such that the full horizontal and vertical extent of contamination exceeding MCLs (estimated to
be approximately 140 feet bgs) would be contained.

A performance and compliance sampling program (PCSP) will be implemented during the remedial action to
monitor performance and compliance with the RAOs. This program will be developed during the
implementation of the selected interim remedy and will include locations of performance monitoring
points, monitoring freguency, analytical parameters, sampling and analytical methods, and statistical
methods for evaluating data. The PCSP will be designed to provide information to evaluate the
effectiveness of the interim remedial action. The PCSP will be included as part of the work plans
developed for this interim action, and will be reviewed and approved by Hill AFB, UDEQ, and EPA
regulators. The PCSP may be modified during the interim remedial action if site conditions change.

6.1.2. Restoration Time Frame

Because this action is an interim solution designed only to contain the ground-water contamination plume,
a restoration time frame for cleaning up the ground water is not applicable to this interim action. This
interim system will operate until the final remedy is implemented (expected to be within six years) and
if it proves to be an effective measure, it may be included as a component of the final remedy.

6.1.3. Costs

The total capital cost of the project is estimated at $750,000. The total capital cost includes:
installation of the extraction well network (approximately 8 wells), pumps, conveyance piping to the
sanitary sewer, and electrical and instrumentation components. The indirect capital cost for the project
is estimated at $220,000 and is included in the estimated total capital cost cited above. Indirect costs
include engineering, contingency, and contract administration.

Operation and maintenance (O&M) costs over the duration of the interim remedial action are calculated for
a six-year period. Annual O&M is estimated at $135,000 per year. O&M costs include power consumption,
labor, well rehabilitation, regular maintenance, sanitary sewer treatment charges, guarterly ground-water
monitoring program, and discharge water to the sanitary sewer. It was assumed that rehabilitation of each
well will occur once during the duration of this interim remedial action at an estimated cost of $8,000
-------
for 8 extraction wells. The total present worth cost of the selected interim remedy over a six-year
period, using an interest rate of ten percent, was estimated at $1,305,000. These cost estimates should
be accurate to within +50% to -30% of the actual cost. During the implementation process for the selected
alternative, modifications resulting from the engineering design process could change the estimated costs
for this alternative.

6.2 STATUTORY DETERMINATIONS

The selected interim action for Hill AFB OU 8 meets the statutory requirements of CERCLA. These statutory
requirements include protection of human health and the environment, compliance with ARARs (within the
scope of the IRA), cost effectiveness, and utilization of permanent solutions and alternative treatment
technologies to the maximum extent practicable. Contaminant treatment is provided at the POTW. The manner
in which the selected interim action for OU 8 meets each of the requirements is presented in the
following discussion.

6.2.1. Protection of Human Health and the Environment

The selected interim remedy for OU 8 is protective of human health and the environment. The contaminated
ground water currently migrating to off-Base areas contributes to a future threat to human health and the
environment. Implementation of the selected interim remedy represents a preliminary step in achieving
long-term protection by preventing or minimizing transport of contaminants to off-Base areas.

6.2.2. Compliance with Applicable or Relevant and Appropriate Requirements

Section 121(d) (1) of CERCLA, as amended by SARA, requires that the interim remedial action proposed for
OU 8 must attain, to the extent practical under the selected interim remedial action, 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,
the State of Utah ARARs include all promulgated standards and rules associated with delegated State
environmental programs, and those State regulations with no corresponding Federal regulations.

"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 action,
location, or other circumstance at the OU 8 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 action, location, or other circumstance 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, action-specific, or location-specific.
According to the NCP, chemical-specific ARARs are usually 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. Action-specific ARARs are usually 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. Location-specific ARARs generally are restrictions
placed upon the concentration of 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.

The interim action selected for OU 8 will meet the ARARs that are applicable or relevant and appropriate
to this interim remedial action. Chemical- and action-specific ARARs for the selected interim action are
identified in Table 6-1. Federal and State location-specific ARARs are not applicable nor relevant and
appropriate to the OU 8 selected interim remedy. A summary of ARARs to be met with alternate discharge
options (Alternative 5-IWTP) is presented in Table 6-2. The ARARs listed in Table 6-2 will be applicable
only if the IWTP discharge option is selected at a later date and if greater treatment efficiency, cost
effectiveness, or ease of implementation can be established for an interim action at Operable Unit 8.
Because the principal goal of this interim action is hydraulic containment of ground water at the Base
boundary, restoration of the contaminated aquifer to drinking water standards is outside the scope of
-------
this interim action. Aquifer restoration will be addressed during the selection of the final remedy for
all of OU 8. For this reason, regulations that address restoration of contaminated ground water are not
ARARs for this interim action. These ARARs include MCLs, the Utah ground water quality standards, and the
Safe Drinking Water Act.

Discharge to the POTW will comply with the national pretreatment standards and limits established by the
POTW pretreatment program. Air emission requirements are met by complying with the fugitive dust
regulations and the air emissions requirements for the Base air emissions permit. Hazardous waste
generator and listing of hazardous waste will comply with all requirements involving off-Base disposal of
soils. The ground-water protection rule will be met by complying with the ground-water monitoring
provisions. In addition, the design of all monitoring and extraction wells will be completed in
accordance to the appropriate drilling and completion standards.

Hill AFB obtained approval at a September 15, 1995, board meeting from the NDCSD to increase the
discharge to the sanitary sewer. Hill AFB also will complete amendments to the "CERCLA Wastewater
Discharge" clause to the existing utility contract before initiating additional discharge to the sewer.
All air quality and local discharge limits are expected to be met with this alternative.

6.2.3. Cost Effectiveness

Overall cost effectiveness can be defined as the overall effectiveness proportionate to cost, such that
an action represents a reasonable value. The selected remedy for OU 8 will contain ground water at the
Base boundary at a reasonable cost, thus providing protection to human health and the environment. The
selected interim action also has a cost that is within the same range as the other action alternatives.
If greater treatment efficiency, cost effectiveness or ease of implementability can be established at a
later date, other discharge alternatives would be considered, such as the IWTP.

6.2.4. Utilization of Permanent Solutions and Treatment Alternative Technologies or Resource Recovery
Technologies to the Maximum Extent Practical

The selected remedy for OU 8 does not provide on-site treatment; however, extracted ground water will be
treated at the POTW. Hence, the selected remedy for OU 8 utilizes permanent solutions to the maximum
extent practical. The statutory preference for treatment as a principal element for ground water as a
whole will be addressed in the final Record of Decision for OU 8. However, this remedy is only an interim
measure and its effectiveness will be evaluated in the final decision document for OU 8. If greater
treatment efficiency or cost effectiveness can be established at a later date, discharge of extracted
groundwater to the IWTP (Alternative 5) may again be considered.

The selected interim action 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 most critical in the selection of this remedy was implementability. Alternative 4 will be
easy to implement because it will utilize direct discharge to a sanitary sewer, which eliminates the need
for constructing an additional treatment facility. To an extent, this Alternative Is not affected by the
changing site conditions (e.g., a decrease in contaminant concentrations). The modifying criteria, which
are State and community acceptance, have had an effect on selection of the remedy. The State agrees with
the selected remedy. However, one of the community members had expressed cost concerns over selection of
Alternative 5 as the preferred remedy. Given additional information suggesting the zone to be contained
is smaller with lower concentrations, Hill AFB now concurs with the community member. Hill AFB has,
therefore, selected Alternative 4 as the remedy for an interim action at OU 8.

6.3 DOCUMENTATION OF SIGNIFICANT CHANGES

The Proposed Plan for an interim action at Hill AFB OU 8 (Montgomery Watson, 1995c) was released for
public comment in July 1995. The Proposed Plan identified Alternative 5 - ground-water extraction,
treatment at IWTP, and discharge to a sanitary sewer as the preferred alternative; one modification to
the Proposed Plan was made and included eliminating carbon treatment of air emissions. This change was
necessary to make this alternative consistent with the current operations at the IWTP.
-------
TABIiE 6-1
SUMMARY OF ARARs FOR THE SEIiECTED REMEDY
Alternative

Alternative 4
(Discharge to Sanitary
Sewer)
ARARs With Which the Alternatives Must Comply

• R307-1-2 UAC
(Utah Air Conservation Rules - general requirements)
• R307-1-3 UAC
(Emission standards for control of installations)
• R307-1-4 UAC
(Emission standards)
• R307-1-4 UAC
(Emission standards)
• R307-10 UAC
(Utah NESHAPs Standards)
• R307-12 UAC
(Fugitive Dust Emission Standards)
• R307-14 UAC
Emission Standards for Ozone Non-Attainment Areas, Davis and Salt Lake
Counties)
• R315-2 UAC
(General requirements - identification and listing of hazardous waste)
• R315-5 UAC
(Hazardous waste generator requirements)
• R315-8-6 UAC
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
• R317-1 UAC
(Definitions for water pollution rules and general requirements)
• R317-2 UAC
(Standards for quality of waters of the State)
• R317-6 UAC
(Ground-water quality protection rule)
• R317-8 UAC
(Utah pollution discharge elimination system)
• R655-4 UAC
(Standards for drilling and abandonment of wells)
• 40 CFR Parts 122-125
(National pollution discharge elimination System)
• 40 CFR. Part 264, Subpart F
(Requirements for detection and containment of releases)
• 40-CFR Part 270
(Hazardous waste permit program)
• 40 CFR Part 403
(National pretreatment standards)
ARAR Applicable or relevant and appropriate requirement
CFR Code of Federal Regulations
RCRA Resource Conservation and Recovery Act
TSDF Treatment, storage, and disposal facility
UAC Utah Administrative Code
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TABLE 6-2
SUMMARY OF ARARs FOR THE OPTIONAL REMEDY
Alternative

Alternative 5
(Treatment at IWTP and
Discharge to Sanitary Sewer)
ARARs With Which the Alternatives Must Comply

• R307-1-2 UAC
(Utah Air Conservation Rules-general reguirements)
• R307-1-3 UAC
(Emission standards for control of installations)
• R307-1-4 UAC
(Emission standards)
• R307-10 UAC
(Utah NESHAPs Standards)
• R307-12 UAC
(Fugitive Dust Emission Standards)
• R307-14 UAC
Emission Standards for Ozone Non-Attainment Areas, Davis and Salt Lake
Counties)
• R315-2 UAC
(General reguirements - identification and listing of hazardous waste)
• R315-5 UAC
(Hazardous waste generator reguirements)
• R315-8-6 UAC
(Ground Water Protection Standards for Owners and Operators of
Hazardous Waste TSDFs)
• R317-1 UAC
(Definition of water pollution rules and general reguirements)
• R317-2 UAC
(Standards for guality of waters of the State)
• R317-8 UAC
(Utah pollution discharge elimination system)
• R655-4 UAC
(Standards for drilling and abandonment of wells)
• 40 CFR Part 50
(Primary and secondary air guality standards)
• 40 CFR Part 61, Subpart A
(NESHAPs Standards)
• 40 CFR Part 261
(Identification and listing of hazardous waste)
• 40 CFR. Part 264, Subpart F
(Reguirements for detection and containment of releases)
ARAR Applicable or relevant and appropriate reguirement
CFR Code of Federal Regulations
RCRA Resource Conservation and Recovery Act
TSDF Treatment, storage, and disposal facility
UAC Utah Administrative Code
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Further investigation work has been conducted since the Proposed Plan for OU 8 IRA was released. The
recent fieldwork focused on further delineation of the contaminant plume and definition of aquifer
characteristics along the southern Base boundary. This investigation included CPT (13 locations, 130 to
200 feet bgs) and hydropunch sampling (13 locations at 3 to 5 depths at each location) , installation and
sampling of monitoring wells (5 wells), installation of three ground-water extraction wells and
piezometers, and the performance of three constant pump rate aguifer tests.

The results of this field investigation indicate that the extent of the contaminant plume is not as
extensive as suggested by previous investigations. This has resulted in a much smaller area of
attainment. The horizontal extent of the contaminant plume is now believed to extend approximately 800
feet along the Southern Base Boundary, compared to approximately 2,000 feet as indicated in the previous
documents. Further, the concentrations of contaminants detected in the OU 8 area are lower than
previously understood.

Results of the recent investigation have made Alternative 4 more feasible, both technically and
economically. The chances of discharge from the IRA system exceeding the NDCSD discharge permit levels
have been reduced significantly. Reduced contaminant loading from the IRA discharge would lower the
discharge fee to be levied by the NDCSD. In addition, the smaller horizontal extent of contamination
means fewer extraction wells and, thus, less volume of extracted ground water. This will further reduce
the cost associated with direct discharge to a POTW.

Written and verbal comments received during the public comment period expressed concerns over the cost
effectiveness of Alternative 5 and discharge to the IWTP. Hill AFB agrees with the comment. Changing the
preferred remedy for the OU 8 IRA to Alternative 4 addresses those concerns. A copy of the proceedings of
the Proposed Plan open house, as well as the comments received, are included as Appendices A and B,
respectively.

Selection of Alternative 4 as the preferred remedy does not change the principal element of remedy for
the IRA--containment of ground water at the Base boundary of Hill AFB to prevent off-Base transport of
contaminants above MCLs. However, Alternative 4 relies on off-site treatment (POTW) to reduce the volume
and toxicity of the ground-water contaminants.

The selected remedy for an interim action for Operable Unit 8 is Alternative 4--Ground-Water Extraction
and Discharge to Sanitary Sewer. The EPA and UDEQ concur with the selected remedy. If greater treatment
efficiency, cost effectiveness or ease of implementability can be established at a later date, discharge
of extracted groundwater to the IWTP (Alternative 5) may again be considered.
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Hill Air Force Base, Utah
Operable Unit 8

Responsiveness Summary
Overview

This responsiveness summary provides information about the views of the community with regard to the
proposed interim remedial action for Hill AFB OU 8, documents how public comments have been considered
during the decision making process, and provides responses to concerns.

The public was informed of the selected remedial action 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 August 8, 1995, through September 7, 1995.

• Three thousand flyers were sent to area residences announcing the public Open House.

• A public Open House was held on August 17, 1995, at Northridge High School, Layton, Utah.

• Written comments by the public were encouraged.

The public Open House was well attended, and residents provided written concerns about the proposed
action. A copy of the written comments received at the public meeting is attached as Appendix B. As
indicated in the Record of Decision, one community member expressed cost concerns over selection of
Alternative 5 as the preferred remedy. After further consideration, Hill AFB agrees with the community
member and has selected Alternative 4 as the preferred remedy. No verbal comments were received by the
court reporter during the Open House. The transcript of the Open House is presented in Appendix A.

Background on Community Involvement

The public participation reguirements of CERCLA Sections 113(k)(2)(B)(i-v) and 117 were met. Hill AFB has
a Community Relations Plan (Hill AFB, 1992) that is revised as necessary. The community relations
activities include: (1) a Restoration Advisory Board (RAB), which meets regularly 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) presentations and
updates are given at semi-annual town council meetings, (7) opportunities for public comment on remedial
actions, (8) community interviews, and (9) support for the community in obtaining technical assistance
grants (TAGs).

The Focused FS Report for OU 8 (Montgomery Watson, 1995b), and the Proposed Plan for OU 8 (Montgomery
Watson, 1995c) 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, Ogden Standard Examiner, and
Hilltop Times. A public comment period was held from August 8, 1995, through September 7, 1995. In
addition, a public Open House was held on August 17, 1995. At this meeting, representatives from Hill
AFB, EPA, and the State of Utah answered guestions about the site and the selected remedy. A court
reporter was present to record formal verbal comments or guestions, but none were received. Copies of the
transcript and all written public comments received during the comment period have been placed in the
Administrative Record. Responses to the comments received during the public comment period are included
in this Responsiveness Summary, which is part 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 sections.
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Economics of Treatment Method

One community member expressed his concern that he was not sure that using the existing treatment
facility at the IWTP was the most economical method for treating the extracted ground water. The
community member was told that the use of the existing facility provides some advantages in terms of
implementing the alternative because:

• Hill AFB would not need to construct a new treatment system

• Hill AFB has an existing agreement with the NDCSD for discharge to the sewer

• Hill AFB currently operates the IWTP, and the facility can easily treat the expected and
potential contaminant concentrations.

The community member was also told that the costs associated with using the IWTP are relatively close to
the estimated costs for other treatment methods, but can be more easily controlled than for other
alternatives.

However, recent investigations indicate that the areal extent of the contaminant plume at the southern
Base boundary is not as extensive as previously suggested. Further, the concentration of contaminants are
lower than previously understood. These factors make Alternative 4 more feasible, both technically and
economically. Conseguently, Hill AFB concurs with the concern expressed by the community member and
proposes to select Alternative 4 as the preferred remedy for an interim action at Operable Unit 8.

Alternative Implementation

One community member expressed concern that the current regulatory environment will eventually lead to
cleanup of the site even if this proposed action does not happen, which will then end up costing more.
The community member then stated that the proposed interim action should take place, even if the risks
are minimal, because it will save money over the long term. The community member was told that Hill AFB
plans to implement the interim action as presented in the Proposed Plan and that the community did not
raise any objections to the proposed action. Conseguently, there currently are no obstacles to
implementing this alternative.

General Concerns

One community member indicated that she knew of, within a one-block radius of her house, six cases of
Type II diabetes. The community member was told that diabetes is not a symptom of exposure to the
chemicals of concern for OU 8 and was sent information regarding TCE exposure.

Two community members expressed their satisfaction with the Open House and Proposed Plan and with Hill
AFB's response to their concerns. No response was necessary.

Part II - Comprehensive Response to Specific Legal and Technical Questions

No specific legal and technical guestions were raised by the community.

Remaining Concerns

Several concerns, guestions, and reguests were raised by community members to Hill AFB personnel
informally during the Open House and by telephone during the public comment period. These concerns, and
Hill AFB's responses, are summarized below:

One community member reguested a copy of a report that provides contamination levels of ground water
beneath his property in Layton. Hill AFB provided these results to the community member.

A community member indicated that he knew of a well north of his property that is being used, and he
provided his address to Hill AFB. This community member also reguested information regarding the
long-term effects of TCE exposure at high concentrations because he had worked in a shop area for many
years; he also indicated that he has some health problems. The community member was contacted to obtain
more information about the well, which was found to be used for irrigation and stock watering. The
community member was told that the use of the well would be investigated further during the RI for OU 8.
Regarding TCE exposure, the community member was referred to the Occupational Health Office at Hill AFB
to obtain more information regarding his concern.
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One community member requested a copy of the Proposed Plan as well as drinking water MCLs for
contaminants. These materials were mailed to the community member.

A community member indicated that he smelled a strong, mold-like odor between Hill Field Road and Fort
Lane and requested that Hill AFB investigate the smell. Hill AFB contacted the Davis County Health
Department, who then visited the site to check out the odor. The Davis County Health Department personnel
did not smell the odor at the indicated location. The community member was contacted and told that the
smell was likely due to an agricultural or irrigation source and that he should notify the Health
Department if he smells the odor again.

Three community members reported standing water near their homes, of which one member indicated that he
had a wet basement. Hill AFB personnel visited the site and observed wet areas near some of the property
owners. One soil and two ground-water samples were taken and analyzed for volatile organic compounds. The
soil sample was clean, but both water samples contained low levels of TCE (<10 Ig/1). Hill AFB personnel
contacted the landowners and explained these results and indicated that the concentrations observed did
not represent a health concern. Hill AFB personnel also visited the site with personnel from the city of
Layton and the U.S. Army Corps of Engineers to evaluate the potential for wetlands. While on site, this
group met with landowners and discussed the contamination at the site, indicating that the contamination
does not represent a health threat and will be investigated further during the RI.

A Layton resident called Hill AFB and reported that she has a wet spot in her yard and has had drainage
problems since the Mitchell Plaza was developed several years ago. She indicated that she just wanted to
call to let us know about this. No response was necessary. She will be contacted during the RI.

Another resident called Hill AFB, indicating that her children eat a lot of soil. She was told that no
current risk from soil exists as far as contaminants from Hill AFB and that ground water is the medium of
concern for OU 8. Hill AFB also confirmed with the resident that there are no wet spots in her yard.
A community member called Hill AFB to request information regarding the health effects of TCE exposure.
She indicated that she grew up near the present location of Layton Hills Mall and that she is currently
suffering from a list of health problems ranging from an enlarged liver to dizziness. She indicated that
the neighborhood obtained its water from a local well near the present location of the Sizzler
restaurant. She further stated that the well was tested by the city and found to contain oil and other
unidentified constituents that she says were from Hill AFB. She was told that Hill AFB was planning
additional investigative work in the area, but it was unlikely the well contained contaminant
concentrations that would produce the reported health effects. None of the surrounding wells show signs
of contamination. Other health problems like she described have not been reported to the Health
Department. Neither Hill AFB, the City of Layton, nor Davis County Health Department were aware of the
well, nor the sampling results she referenced.

One community resident telephoned Hill AFB and reported that she was concerned about contamination,
particularly with respect to her garden. The community member was told that, based on the available data,
there shouldn't be any health effects from the contamination. She was also told that the area where she
lives is drained by field drains that transport the water away from her housing development. Hill AFB
also sent her the Proposed Plan for the interim action.
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REFERENCES

Battelle, 1994. UST Site 280 Final Report on Bioremediation of Hazardous Wastes at CERCLA and RCRA Sites:
Hill AFB 280 Site Low Intensity Bioreclarnation.

Chen-Northern 1989. Pond 3 Site Evaluation Report, Hill Air Force Base, Ogden, Utah. Prepared for Hill Air
Force Base, September 1989.

Environmental Science and Engineering (ESE) 1989a. Data Compilation Report RI/FS Berman Pond and Building
514 Area, March 1989.

Environmental Science and Engineers, Inc., (ESE) 1989b. Layton Groundwater Investigation, March 1989.

Feth, J.H., D.A. Barker, L.G. Moore, R.J. Brown, and C.E. Veirs, 1966. Lake Bonneville: Geology and
Hydrology of the Weber Delta District including Ogden, Utah. U.S. Geological Survey Professional
Paper 518.

Hill Air Force Base, 1992. Installation Restoration Program Environmental Community Relations Plan,
February, 1992.

Hill Air Force Base, 1984. Hill Air Force Base Civil Engineers Sodium Hydroxide Tank Site Investigation,
(Unpublished data).

James M. Montgomery, Consulting Engineers, Inc. (JMM), 1989a. Summary of Site Characterization Data
Collected During 1988 in the IWTP Area, Hill AFB, Utah, March 1989.

James M. Montgomery, Consulting Engineers, Inc. (JMM) , 1989b. Internal Draft Remedial Investigation
Report for Operable Unit 3 at Hill Air Force Base, Utah, July 1989.

James M. Montgomery, Consulting Engineers, Inc. (JMM), 1992a. Draft Final Remedial Investigation Report
for Operable Unit 3 at Hill Air Force Base, Utah, April 1992.

James M. Montgomery, Consulting Engineers, Inc. (JMM), 1992b. Final Subsurface Report for UST Site 204.
1, Hill Air Force Base, Utah, December 1992.

James M. Montgomery, Consulting Engineers, Inc. (JMM), 1992c. Draft Final Corrective Action Plan for UST
Site 22, Hill Air Force Base, Utah, November. 1992.

James M. Montgomery, Consulting Engineers, Inc. (JMM), 1992d. Final Abatement and Initial Site
Characterization Report for UST Site 236, Hill Air Force Base, Utah, July 1992.

Montgomery Watson, 1994a. Draft Final Environmental Assessment for Operable Unit 8, Hill Air Force Base,
Utah, December 1994.

Montgomery Watson, 1994b. Draft Final Remedial Investigation Report Addendum for Operable Unit 3, Hill
Air Force Base, Utah.

Montgomery Watson, 1994c. Draft Subsurface Characterization Report, Corrective Action Plan, and Free
Product Removal Report for UST Site 260, Hill Air Force Base, Utah, June 1994.

Montgomery Watson, 1995a. Final Data Summary and Recommendations Report for Operable Unit 8, Hill Air
Force Base, Utah, January 1995.

Montgomery Watson, 1995b. Final Interim Remedial Action Focused Feasibility Study for Base Boundary,
Operable Unit 8, Hill Air Force Base, Utah, August 1995.

Montgomery Watson, 1995c. Final Proposed Plan for Operable Unit 8, Hill Air Force Base, Utah, August
1995.

Montgomery Watson, 1995d. Final First and Second Monitoring Rounds Data Evaluation for Operable Unit 8,
Hill Air Force Base, Utah, March 1995.

Montgomery Watson, 1995e. Final RI/FS Report for OU 7, Hill Air Force Base Utah, February 1995.

Montgomery Watson, 1995f. Final RI/Fs Work Plans for OU 8, Hill Air Force Base, Utah, June 1995.
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Montgomery Watson, 1996a. OU 8 Off-Base Drainage Survey, Water User Survey, and Residential Survey Letter
Report, Hill Air Force Base, Utah, December 1996.

Montgomery Watson, 1996b. Interim Remedial Action Field Work Data Summary and Remedial Design Technical
Memorandum for Operable Unit 8, Hill Air Force Base, Utah, March 1996.

Radian Corporation, 1988a. Installation Restoration Program Phase II, Stage 2, Hill Air Force Base, Utah,
July 1988.

Radian Corporation, 1988b. Installation Restoration Program Phase II - Confirmation/Quantification Stage
I Building 220, Paint Hangar, Prepared for Hill Air Force Base, Utah, May 1988.

Radian, 1989. Pond 2 Investigation, (Unpublished data).

Sergeant, Hauskins and Beckwith (SHE), 1985. Field Soil Boring Logs and Sketch Maps for a Site
Investigation at the IWTP Sludge Drying Beds, Hill Air Force Base, Utah.

UBTL, Inc., 1984, Hill AFB, Utah. Installation Restoration Program Phase IB Survey, Final Report,
September 1984.

United States Geological Survey (USGS) , 1992. Final RI Report for Operable Unit 4. Prepared for U.S. Air
Force Logistics Command, September 1992.
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APPENDIX A

PUBLIC MEETING TRANSCRIPT

The public meeting transcript is attached as Appendix A.

1 REPORTER'S STATEMENT

3 I, Shirlyn Sharpe, Certified Shorthand Reporter and

4 Notary Public for the State of Utah, do hereby state;

5 That I attended the public meeting for the Public Open

6 House for Operable Unit 8 at Hill Air Force Base held at

7 Northridge High School, Hill Air Force Base Road, Layton,

8 Utah on August 17, 1995, from 4:00 p.m. to 9:00 p.m.;

9 That I was available to record any comments from the

10 attendees there present;

11 That no one appeared before me to make any such public

12 comment or statement.

25
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APPENDIX B

WRITTEN COMMENTS AND RESPONSES

The submittal of written comments from community members was requested at the public Open House and
during the public comment period. Forms asking specific guestions regarding the Open House format, the
RI/FS process, and the preferred alternatives were available at the public Open House, and attendees were
encouraged to respond. The following comments were received; where appropriate, Hill AFB's responses are
also included.

COMMENTS RECEIVED FROM ANONYMOUS COMMUNITY MEMBER
(See pages following this cover page)

HILL AFB RESPONSE

1. Economics of Treatment Method. Hill AFB screened all available technologies for treating the ground
water removed by the proposed hydraulic containment system. Alternative 5, although having the highest
cost of the five alternatives, is still within the cost ranges estimated for the other three
alternatives involving ground water extraction and treatment. Further, use of the existing system
provides advantages for the following reasons:

• Hill AFB would not need to construct a new treatment system

• Hill AFB has an existing agreement with the NDCSD for discharge to the sewer

• Hill AFB currently operates the IWTP, and the facility can easily treat the expected and
potential contaminant concentrations.

Additionally, if contaminant concentrations in the extracted ground water increase, the costs
associated with Alternatives 2, 3, and 4 would increase significantly, while costs for Alternative 5
would remain essentially the same because the IWTP at Hill AFB is designed to treat highly
concentrated wastes.

2. Alternative Implementation. Hill AFB intends to implement the proposed action and agrees that no
action now will result in increased costs later due to spread of the contamination. Based on public
comments, community members were not against implementing the proposed action. Conseguently, there
currently are no obstacles to implementing this action as planned.

COMMENT'S RECEIVED FROM MS. JENE W. SMITH
(See pages following this cover page)

BELL AFB'S RESPONSE

1. Health Concerns (Diabetes). Diabetes is not a symptom of exposure to the chemicals found in OU 8
ground water.

COMMENTS RECEIVED FROM MS. MYRLE CROWN
(See pages following this cover page)

HILL AFB'S RESPONSE

None Required.

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COMMENTS RECEIVED FROM MR. SCOTT PAXMAN
(See pages following this cover page)
HILL AFB'S RESPONSE

None Reguired.
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