EPA Superfund
Record of Decision:
PB96-964420
EPA/ROD/R08-96/130
March 1997
Hill Air Force Base,
Operable Unit 2, Ogden, UT
9/30/1996
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P7103G02/E1/DRAWINGS/COVER.FH3
Hill Air Force Base, Utah
Final
Record of Decision and
Responsiveness Summary
for Operable Unit 2
Contract F42650-92-D-0006,
Delivery Order 5008
September 1996
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FINAL RECORD OF DECISION
FOR OPERABLE UNIT 2
HILL AIR FORCE BASE, UTAH
This is a primary document for Operable Unit 2 at Hill Air Force Base. It will be available in the
Administrative Record, which will be maintained at the following locations:
Davis County Library
Central Branch
155 North Wasatch Drive
Layton, Utah 84041
Hours: Monday through Thursday 11:00 am - 9:00 pm
Friday through Saturday 11:00 am - 6:00 pm
Environmental Management Directorate
OO-ALC/EMR
Building 5
7274 Wardleigh Road
Hill AFB, Utah 84056-5137
Contact: Ms. Gwen Brewer (801) 777-0359
Submittal Date:
SLORME70158.FO\FINAL\RODFINALDOC
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CONTENTS
DECLARATION FOR THE RECORD OF DECISION.,
1. SITE NAME, LOCATION, AND DESCRIPTION 1-1
2. SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-1
2.1 HISTORY OF SITE ACTIVITIES 2-1
2.2 ENFORCEMENT ACTIVITIES 2-1
2.3 INVESTIGATION HISTORY 2-2
2.4 HIGHLIGHTS OF COMMUNITY PARTICIPATION 2-2
2.5 SCOPE AND ROLE OF OPERABLE UNIT 2 WITHIN SITE STRATEGY 2-3
3. SUMMARY OF SITE CHARACTERISTICS 3-1
3.1 TOPOGRAPHY AND HYDROGEOLOGY 3-1
3.2 NATURE AND EXTENT OF CONTAMINATION 3-2
3.3 CONTAMINANT TRANSPORT 3-11
4. SUMMARY OF SITE RISKS 4-1
4.1 HUMAN HEALTH RISKS 4-1
4. J.I Chemicals of Potential Concern 4-1
4.1.2 Exposure Assessment. 4-4
4.1.3 Toxicity Assessment 4-8
4.2 SUMMARY OF RISK CHARACTERIZATION 4-9
4.3 ENVIRONMENTAL EVALUATION 4-21
4.4 UNCERTAINTY IN THE RISK ASSESSMENT 4-22
4.5 OVERVIEW OF SITE RISKS 4-24
5. DESCRIPTION OF ALTERNATIVES 5-1
5.1 DEVELOPMENT OF ALTERNATIVES 5-1
5.2 DETAILED ANALYSIS OF ALTERNATIVES 5-7
5.2.1 Source Area Alternatives 5-8
5.2.2. Non Source Area Alternatives 5-72
6. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 6-1
6.1 THRESHOLD CRITERIA . 6-2
6.7.7 Overall Protection of Human Health and the Environment 6-2
6.7.2 Compliance with ARARs 6-3
6.2 PRIMARY BALANCING CRITERIA 6-5
6.2.7 Long-Term Effectiveness and Permanence 6-5
6.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment 6-6
6.2.3 Short-Term Effectiveness 6-7
6.2.4 Implementability 6-8
6.2.5 Cost 6-9
6.3 MODIFYING CRITERIA 6-10
6.3.7 State Acceptance 6-70
6.3.2 Community Acceptance 6-70
7. THE SELECTED REMEDY 7-1
7.1 DESCRIPTION OF THE SELECTED REMEDY 7-1
7.7.7 Remediation Goals and Performance Standards 7-4
7.7.2 Restoration Time Frame 7-6
7.7.3 Costs 7-6
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7.2 STATUTORY DETERMINATIONS 7-7
7.2.7 Protection of Human Health and the Environment 7-7
7.2.2 Compliance with Applicable or Relevant and Appropriate Requirements 7-8
7.2.3 Cost-Effectiveness 7-10
7.2.4 Utilization of Permanent Solutions and Alternative Treatment Technologies 7-10
7.2.5 Preference for Treatment as a Principal Element 7-77
7.3 DOCUMENTATION OF SIGNIFICANT CHANGES 7-11
8. REFERENCES 8-1
9. RESPONSIVENESS SUMMARY 9-1
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List of Figures, Tables, and Appendices
Figures
FIGURE l-l LOCATION OF HAFB 1-2
FIGURE 1-2 LOCATION OF OU2 1-3
FIGURE 1-3 EXTENT OF GROUNDWATER SYSTEMS AT OU2 1-5
FIGURE 1-4 GENERALIZED CROSS-SECTION 1-6
FIGURE 3-1 POTENTIOMETRIC SURFACE FOR SHALLOW OU2 WELLS 3-4
FIGURE 3-2 LOCATION OF DNAPL POOLS 3-5
FIGURE 3-3 DELINEATION OFTCE PLUME 3-6
FIGURE 3-4 DELINEATION OF TCA PLUME 3-7
FIGURE 3-5 DELINEATION OF PCE PLUME 3-8
FIGURE 5-1 DELINEATION OF SOURCE AREA AND NON-SOURCE AREA AT OU2 . 5-3
List of Tables
TABLE 3-1 CHEMICAL CONTAMINANTS DETECTED IN SOIL, SURFACE WATER, AND GROUNDWATER 3-4
TABLE 4-1 MEDIA SPECIFIC CHEMICALS OF POTENTIAL CONCERN AND CONCENTRATIONS USED
IN RISK ASSESSMENT ADDENDUM : 4-2
TABLE 4-2 CHEMICALS OF CONCERN 4-4
TABLE 4-3 MATRIX OF POTENTIALLY EXPOSED POPULATIONS AND RELEVANT EXPOSURE PATHWAYS ... 4-5
TABLE 4-4 TOXICITY VALUES FOR CHEMICALS OF POTENTIAL CONCERN 4-10
TABLE 4-5 IDENTIFICATION OF KEY CHEMICALS AND EXPOSURE PATHWAYS IN THE RA ADDENDUM
THAT DRIVE THE CARCINOGENIC RISK ASSESSMENT 4-13
TABLE 4-6 IDENTIFICATION OF KEY CHEMICALS AND EXPOSURE PATHWAYS IN THE RA ADDENDUM
THAT DRIVE THE NONCARCINOGENIC RISK ASSESSMENT 4-15
TABLE 4-7 SUMMARY OF CARCINOGENIC RISKS BY EXPOSURE SCENARIO 4-19
TABLE 4-8 SUMMARY OF NONCARCINOGENIC RISKS FOR CHRONIC AND SUBCHRONIC EXPOSURE
SCENARIOS 4-22
TABLE 4-9 SUMMARY OF UNCERTAINTIES 4-23
TABLE 5-1 SOURCE AREA ALTERNATIVES FOR GROUNDWATER 5-4
TABLE 5-2 SOURCE AREA ALTERNATIVES FOR SOIL 5-5
TABLE 5-3 NON-SOURCE AREA ALTERNATIVES 5-6
TABLE 6-1 SUMMARY OF COSTS FOR OU2 SOURCE AND NON-SOURCE AREA ALTERNATIVES 6-11
TABLE 7-1 CHEMICALS OF CONCERN AND REMEDIATION GOALS FOR HAFB OPERABLE UNIT 2 7-6
TABLE 7-2 SUMMARY OF COSTS FOR THE SELECTED REMEDY AT HAFB OPERABLE UNIT 2 7-7
APPENDIX A
APPENDIX B
APPENDIX C
Appendices
IDENTIFICATION OF ARARS
TRANSCRIPT OF PUBLIC MEETING
WRITTEN COMMENTS
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Glossary of Acronyms
ARAR applicable or relevant and appropriate requirements
BACT Best Available Control Technology
bgs below ground surface
BRA Baseline Risk Assessment
CAMU Corrective Action Management Unit
CDI chronic daily intake
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
COC Chemical of Concern
COPC Chemical of Potential Concern
CPT cone penetrometer testing
DCE 1,2-Dichloroethene
DNAPL dense, non-aqueous phase liquid
EPA U.S. Environmental Protection Agency
FS Feasibility Study
HAFB Hill Air Force Base
HI hazard index
HQ hazard quotient
IRM intermediate remedial measures
IRP Installation Restoration Program
IWTP Industrial Water Treatment Plant
LDR Land Disposal Restriction
MCL maximum contaminant level
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NESHAPS National Emission Standards for Hazardous Air Pollutants
NPL National Priorities List
OU Operable Unit
PA Preliminary Assessment
PCE Tetrachloroethylene
POTW Publicly Owned Treatment Works
PRG proposed remediation goal
RAB Restoration Advisory Board
RCRA Resource Conservation and Recovery Act of 1976
RD remedial design
Rfd reference dose
RI remedial investigation
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act of 1986
SF slope factor
SRS Source Recovery System
SVE soil vapor extraction
SVOC semi-volatile organic compound
TAG technical assistance grant
TCA trichloroethane
TCE trichloroethylene
TDS total dissolved solids
TRC Technical Review Committee
UAC Utah Administrative Code
UCL upper confidence limit
UDEQ Utah Department of Environmental Quality
UST Underground Storage Tanks
VOC volatile organic compound
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
DECLARATION FOR THE RECORD OF DECISION
Site Name and Location
Operable Unit 2
Hill Air Force Base, Utah
Davis County, Utah
Statement of Basis and Purpose
This decision document presents the selected remedy for Operable Unit 2 (OU2) at Hill Air
Force Base (HAFB), Utah. It was selected in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended
by the Superfund Amendments and Reauthorization Act of 1986 (SARA), and to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
This decision is based on the Administrative Record for this site.
The State of Utah and the U.S. Environmental Protection Agency (EPA) concur with the
selected remedy.
Assessment of the Site
Actual or threatened releases of hazardous substances from the site, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may present
an imminent and substantial endangerment to public health, welfare, or the environment.
Description of the Selected Remedy
OU2 (IRP Site WP007) is addressed in two components, the source area and the non-source
area. The source area is on-Base and is the immediate area around the former Chemical
Disposal Pit 3 that is underlain by a dense, non-aqueous phase liquid and affected areas
west of Perimeter Road. This area has the highest concentrations of contaminants, and
occupies approximately 6 acres. The non-source area is north and east of the source area
and Perimeter Road. The non-source area includes shallow groundwater and seep and
spring contamination off-Base. This area generally has lower contaminant concentrations
and occupies approximately 25 acres.
The remedy selected for OU2 addresses contaminated groundwater, contaminated soil, and
contaminated surface water at OU2. This ROD also addresses a dense, non-aqueous phase
liquid (DNAPL) composed mainly of chlorinated solvents which contributes to
contamination of groundwater. The selected remedy for OU2 addresses the principal
threats posed by the site by minimizing or preventing direct contact with contaminated
soils; preventing ingestion of and direct contact with contaminated groundwater and
surface water; and preventing further offsite transport of contaminants.
The selected remedy for the OU2 source area includes:
an encircling vertical barrier
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
shallow groundwater extraction and treatment, and discharge
soil vapor extraction (SVE) to remove volatile organic compounds (VOCs) from
subsurface soils
continued operation of the source recovery system (SRS) to remove dense, non-
aqueous phase liquid (DNAPL) to the maximum extent practicable and for the
treatment of shallow groundwater
a surface cap to prevent further degradation of groundwater
treatability studies planned to address DNAPL contamination include the use of
surfactants and steam injection. If successful, these technologies may be
implemented as part of this remedy. The surface cap will be installed once
treatment is completed or it is established the innovative technologies cannot
meet remedial action objectives.
The selected remedy for the OU2 non-source area includes:
shallow groundwater extraction, treatment, and discharge
continued collection, treatment, and discharge of contaminated water flowing
from springs and seeps
discharge for groundwater treatment systems for the source area and non-source
area is currently planned for the SRS which in turn discharges to the Industrial
Water Treatment Plant (IWTP) on Base. However, as concentrations decrease in
time, it may become more cost-effective to use other on-Site discharge options.
Other options, after necessary treatment, include discharge to the sanitary sewer
where it will be treated further at the Central Weber Sewer Improvement
District, or on-Site discharge to a surface drainage or storm sewer.
The selected remedy for both areas include:
environmental monitoring to evaluate the effectiveness of the remedy
implementing institutional controls to minimize exposure by limiting use and
preventing access to contaminated water and soil
Perimeter Road (IRP Site SS021), investigated as part of OU2, has been found to be free of
contamination except in those areas being addressed as part of existing OUs. No further
action is needed for Perimeter Road as part of OU2.
Statutory Determinations
The selected remedy is protective of human health and the environment; complies with
Federal and State of Utah requirements that are legally applicable or relevant and
appropriate requirements (ARARs) to the remedial action; and is cost-effective. Once the
remedy is complete, ARARs will be met or a waiver will be justified. An ARARs waiver
may be invoked, accompanied by an Explanation of Significant Differences, if it is
SLORME70158.FOFINAL\ROORNALDOC
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
determined on the basis of criteria stated in this ROD that MCLs/MCLGs or other chemical-
specific ARARs cannot be achieved within all portions of the area of attainment or where it
is anticipated that it may be technically impracticable to reach such levels targeted in the
ROD.
This remedy utilizes permanent solutions and alternative treatment technologies to the
maximum extent practicable for this site, and satisfies the statutory preference for remedies
that employ treatment that reduces toxicity, mobility, or volume as a principal element.
Because this remedy will result in hazardous substances on site above health-based levels, a
review will be conducted within 5 years after commencement of remedial actions to ensure
that the remedy continues to provide adequate protection of human health and the
environment.
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Maxwell H. Dodson, DATE
Assistant Regional Administrator
Office of Ecosystems Protection and Remediation
EPA Region V1H
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9/17/96
RECORD OF DECISION FOR OPERABLE UNIT 2
STATE OF UTAH DEPARTMENT OF ENVIRONMENTAL
)UALITY _
Dianne R. Nieison, Ph.D.,
Executive Director
DATE
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
HILL AIR FORCE BASE, UTAH
Thomas W. L. McCall, DATE
Deputy Assistant Secretary of Air Force
(Environment, Safety, and Occupational Health)
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
1. SITE NAME, LOCATION, AND DESCRIPTION
Hill Air Force Base (HAFB) is located in northern Utah, approximately 25 miles north of Salt
Lake City and about 5 miles south of Ogden, Utah (Figure 1-1). HAFB occupies
approximately 6,700 acres in Davis and Weber Counties. The base is bounded on the west
by Interstate 15, on the south by State Route 193, and on the northeast by the Weber River
Valley (Figure 1-2). The base is located on a prominent terrace known as the Weber Delta.
Operable Unit 2 (OU2), one of nine OUs at HAFB, is located along the northern boundary of
the Base (Figure 1-2). Areas investigated as part of OU2 consist of Perimeter Road and two
unlined trenches known together as Chemical Disposal Pit 3. The trenches are now
obscured by facilities of the Source Recovery System (SRS). The SRS was installed as part of
an interim remedial action to extract as much of a dense, non-aqueous phase liquid
(DNAPL) as practicable. Except for the SRS and Perimeter Road, there are no other
buildings or man-made structures in the on-Base portion of OU2. Traffic is sparse and the
area is seldom used by HAFB for military activities.
Separating the on-Base portion of OU2 from the off-Base portion of OU2 is a steep, terraced,
north-facing escarpment that is the south wall of the Weber River Valley. There is about
300 feet of relief between HAFB and the valley below. Parts of this hillside are unstable and
are known as the Weber Landslide Complex. Numerous seeps and springs occur along the
hillside. Depending on groundwater table conditions and the season, the springs and seeps
discharge water from the shallow groundwater system.
Along this hillside escarpment and just outside of the northeastern boundary is the Davis-
Weber Canal, a privately owned concrete-lined irrigation canal. The canal is located
outside the base boundary and parallels the northeast boundary along most of the extent of
the base adjacent to the Weber River Valley. The canal provides water from the Weber
River for irrigation in the surrounding areas.
At the bottom of the hillside, the land is generally level. Land use in the off-Base part of
OU2 is mostly agricultural and rural-residential in the community of South Weber.
Agricultural use is for crops (alfalfa) and livestock grazing (mostly sheep and horses).
There are no hospitals, retirement or nursing homes, schools, nurseries, or day care centers,
currently located in the vicinity of OU2.
Municipal water for South Weber is supplied by the Weber Basin Conservancy District. The
district provides water from wells which tap deep aquifers believed to be unaffected by
contaminants associated with OU2. Shallow groundwater is not currently used as a source
of drinking water in the area, but was used for irrigation and cattle in the past.
The Bambrough irrigation canal is located adjacent to South Weber Drive. Approximately
4,000 feet northeast of South Weber Drive is the Weber River. Land within OU2 is not
located within the 100-year floodplain. There are no jurisdictional wetlands, as regulated
by the U.S. Army Corps of Engineers, within OU2. There are no uses or known occurrences
of commercially valuable natural resources within OU2 area.
SLC\RME70158.FOF1NAL\RODFINALDOC 1 -1
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HILL AIR FORCE BASE
APPROX SCALE IN MILES
To Evanston
To Evanston
Figure 1-1
LOCATION MAP
Oovtttt Urtt 2. H* A* Fore* But. uun
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OPERABLE UNIT 2
STUDY AREA
HILL
AIR FORCE
BASE
Figure 1-2
LOCATION OF OU2
Urtt 2. H« A* Fore* B«M,
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
The hydrogeologic setting is complex. Based on the available information, there are three
shallow, unconfined groundwater systems. The three groundwater systems are
conceptually shown on Figure 1-3 and consist of: a shallow system extending from the
source area to the elevated portion of the north-south trending knoll; a hillside
groundwater flow system located east of the knoll; and the Weber River alluvium to the
north and east. Figure 1-4 presents a topographic cross-section of OU2 and illustrates the
location of the groundwater flow system.
The degree of hydrogeologic continuity between these systems is difficult to define because
of the complex nature of the geology observed in the off-Base area. This is further
complicated because the steep escarpment between HAFB and the Weber River valley is
part of the Weber Delta Landslide Complex. However, the distribution of major ions in
groundwater flowing through each system shows similarities between the three systems.
The major ion data suggests that these systems may differ from the flow system in which
the background test wells are screened.
SLDRME70158.FOFlNAL\flOORNALDOC 1-4
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'''i'ii'MM&r
Mftfc .!'':
it H«R^$43K&-'=h
siv-prMwvwv-1*-"
FORMER CHEMICAL
DISPOSAL TRENCHES
EXTENT OF QROUNDWATER
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HILL AIR FORCE
BASE
ADAPTED FROM "REMEDIAl INVESTIGATION
REPORT EOR OPERABLE UNIT 2,
VOLUME 1, FIGURE 5-3.
HILL AIR FORCE OASE, UTAH JULY 1092.
HILL AFB OOUTJOARY
APPROXIMATE LOCATION
OF FOR ME II TRENCHES
PERIMETER ROAD
SANO AND GRAVEL
SPRING WITH VOCS
GALLERY AND
HILL AFB TREATMENT
TRAILER
DAVIS-WEBER
CANAL
SPRING
WITH VOCS
SPRING
WITH VOCS
SOUTH WEOER
DRIVE
CLAY WITH
INTEROEDDED
SILTS AND SANDS
DRINKING WATER AQUIFER (SUNSET ?)
V/ATCR-TAOIE
APPROXIMATE CONTACT
OF UPPER COARSE GRAINED
MATERIALS WITH UNDERLYING
O.AYS
PnOVO/ALPINE FM
MIXED CLAYS. SILTY
CXAYS. SANO. AND
GRAVEL
EARTHFLOW
MIXED GRAVELS. SANDS.
SILTS. AND CLAYS
0 200 400
I I I
SCALE IN FEET
Fiyufo 1-4
GENERALIZED CROSS SECTION
Ur»t 2. M4 Air fore* fits*. Ul«n
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
2. SITE HISTORY AND ENFORCEMENT
ACTIVITIES
2.1 History of Site Activities
HAFB has been a major center for missile assembly and aircraft maintenance and repair.
The associated industrial processes include metal plating, degreasing, paint stripping, and
painting. These processes required vise of various chemicals, metal plating solutions,
chlorinated and non-chlorinated solvents, degreasers, petroleum hydrocarbons, acids, and
bases. HAFB records indicate that from 1967 to 1975, former Chemical Disposal Pit 3 was
used for disposing unknown quantities of trichloroethylene (TCE) bottoms from solvent
recovery units and sludge from vapor degreasers. In the early 1940s, an unknown volume
of plating tank bottoms were disposed of at this site.
Perimeter Road provides access to most of the waste disposal areas along the northern part
of the Base. Most of these waste disposal areas were active in the 1960s and 1970s.
Investigative activities along Perimeter Road revealed no evidence of spills or dumping
except in areas already being investigated at part of this or other Operable Units on HAFB.
2.2 Enforcement Activities
In 1987, HAFB was placed on the National Priorities List (NPL) under CERCLA by the U.S.
Environmental Protection Agency (EPA). On April 10,1991, HAFB entered into a Federal
Facilities Agreement with the Utah Department of Environmental Quality (UDEQ) and the
EPA to establish a procedural framework and schedule for developing, implementing, and
monitoring appropriate response actions at the site in accordance with existing regulations.
Prior response actions taken by HAFB to prevent exposure to contamination include:
Providing municipal water connections to five homes known to have been
affected by contamination at OU2.
Collecting and treating contaminated water flowing from springs and seeps.
The treated water is discharged to the original spring drainage.
Installing fences around springs and seeps with contaminated water to prevent
livestock access.
Constructing, as an interim remedial action (IRA), the Source Recovery System
(SRS) to remove DNAPL from the area near the former Chemical Disposal Pit 3.
The ROD for this action was signed September 30,1991. Operation of the SRS
has resulted in the recovery of about 30,000 gallons of DNAPL to date.
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
2.3 Investigation History
Investigative work was conducted in phases under the Installation Restoration Program
(IRP). Phase I activities (Engineering Science, 1982) ranked sites according to their potential
for offsite migration of contaminants. As a result, Chemical Disposal Pit 3 was included for
further investigation in the IRP Phase II Field Survey in 1986, along with 12 other sites.
Sampling activities in the Phase II Field Survey confirmed contamination of groundwater
by TCE and other VOCs in the vicinity of Chemical Disposal Pit 3.
Initially, site characterization focused on the area of the pit in which the highest
concentrations of contaminants were observed in groundwater and where the DNAPL was
discovered. Remedial Investigation (RI) activities progressed to further characterize the
extent of contamination in unsaturated and saturated soil zones, the seeps, springs and
canals; and to evaluate potential down gradient receptors, aquifer properties, and transport
pathways. The first phase of RI work is documented in a "Final RI" report completed in July
1992. Additional site characterization was conducted in a second phase of the remedial
investigation to better define the extent of contamination in the off-Base area, possible
inorganic contamination, statistical characterization of background conditions, and
determining the presence or absence of contamination in the Bambrough Canal. This last
phase of RI work also resulted in a better understanding of the hydrogeologic setting. The
results of this additional site characterization field work have been reported in the "Final
Addendum to the RI Report for OU2" (Radian, April 1994).
The Baseline Risk Assessment (BRA) for OU2 was released to the public in March 1992 and
was based on the RI information available at the time. The final addendum to the RI was
released to the public in April 1994. The FS for OU2 was released to the public in April
1993. The Final Addendum to the FS was released to the public in February 1994. The
Proposed Plan, describing remedial alternatives, was released to the public on May 11,1994,
as discussed in Highlights of Community Participation.
2.4 Highlights of Community Participation
The public participation requirements of CERCLA Sections 113(k)(2)(B)(i-iv) and 117 were
met for the remedy selection process. HAFB has a Community Relations Plan which was
finalized in February of 1992. Because there is generally a high degree of interest within the
adjacent communities, HAFB participates in a series of community involvement activities
that pertain to all of HAFB or specifically to OU 2.
Ongoing community relations activities include: (1) a Restoration Advisory Board (RAB)
which includes representatives of the community and city government, and meets at least
quarterly and is open to the public; (2) mailings of announcements, fact sheets, and
newsletters to interested parties in the community; (3) a bi-monthly newsletter called
"EnviroNews;" (4) visits to nearby schools to discuss environmental issues; (5) semi-annual
presentations at town council meetings; (6) opportunities for public comments on remedial
actions; and (7) participation in technical assistance grant (TAG) program activities with the
South Weber Landfill Coalition (SWLC). The RAB replaced the prior Technical Review
Committee (TRC) in January 1995.
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Specific to OU2, meetings were held with the public to discuss response actions such as the
SRS, alternative water supplies for effected residents, and collection, treatment, and
discharge of contaminated water flowing from springs and seeps. In addition, a public
meeting was held on April 28,1993, to explain and discuss risk assessment and risk
management issues for the communities north of HAFB that are affected by OUI, OU2, and
OU4.
The Proposed Plan, describing remedial alternatives, was released to the public on May 11,
1994, for public comment and was mailed to Federal, State, and local agencies; interested
organizations and citizens; and to residents in the vicinity of OU2. All documents of the
remedial investigation/feasibility study (RI/FS), as they were finalized, were placed in the
Administrative Record located at the Directorate of Environmental Management at HAFB
and at the Central Branch of the Davis County Library located in Layton, Utah.
The notice of availability of the Proposed Plan was announced in the Ogden Standard-
Examiner on May 11,1994. A public comment period was held from May 11 to June 10,
1994. A public availability session was held on May 19,1994, at the South Weber City Hall.
All interested parties on the HAFB mailing list, which includes affected residents, were
notified in writing about the session. The purpose of the availability session was to answer
questions about the remedial alternatives presented in the Proposed Plan and other topics
relevant to OU2 in an informal setting.
A public meeting was held on May 25,1994. At this meeting, representatives of HAFB,
EPA, and the UDEQ answered questions and accepted comments about the site and on the
remedial alternatives under consideration. Copies of the transcript and all written
comments received during the comment period are appendices to this ROD. Responses to
comments received during the public comment period are included in the Responsiveness
Summary of this ROD.
2.5 Scope and Role of Operable Unit 2 within Site Strategy
Response actions at HAFB are structured into nine operable units. Most of the operable
units, including Operable Unit 2, are geographically defined and address all contaminated
media within each unit. Remedial actions are addressed separately for each operable unit
and are at different stages of investigation or remediation.
The selected remedy for OU2 incorporates or develops upon prior response actions
described in Section 2.2 that will continue as part of this remedy. The DNAPL and
groundwater with high concentrations of contaminants in the source area originally
addressed with the SRS are further addressed by containment. VOC contamination of soils
in the source area will be reduced by soil vapor extraction (SVE). Extraction and treatment
of groundwater will reduce concentrations of contaminants and prevent further expansion
of the contaminant plume with hydraulic controls. Collection and treatment of
contaminated seeps and springs will continue.
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
3. SUMMARY OF SITE CHARACTERISTICS
3.1 Topography and Hydrogeology
HAFB covers about 6,700 acres and is located on a terrace approximately 300 feet above the
surrounding valley floors in Davis and Weber Counties. OU2 is located near the northern
boundary of HAFB. The topography is relatively flat in the immediate vicinity of the
disposal pits. The topography drops steeply to the north in the direction of the city of South
Weber, forming a steep hillside. Parts of the hillside are unstable and are known as the
Weber Delta Landslide complex.
Western portions of HAFB overlie two deeper confined aquifers. The Sunset and Delta
Aquifers are generally located about 300 and 500 feet below the ground surface,
respectively. Municipal groundwater supplies in the area are obtained from these aquifer
systems. It is unclear if the Sunset and Delta are separate aquifer systems beneath OU2.
Both aquifers would be either Class I - Irreplaceable Source of Drinking Water or Class HA -
Current Source of Drinking Water, under EPA's groundwater classifications. Natural
regional flow directions for these aquifers is westward.
A silty clay unit separates shallow contaminated groundwater from the deeper confined
units and is approximately 200 feet thick. This formation is of low permeability which
impedes the downward migration of contaminants into the deeper aquifers.
Contaminants are found in the shallow unconfined groundwater systems at HAFB.
Interpretation of the hydrogeologic conditions of the off-Base area suggests three shallow
unconfined groundwater systems in the vicinity of OU2. The three groundwater systems
are conceptually shown on Figure 1-3 and consist of: a shallow system extending from the
source area to the elevated portion of the north-south trending knoll; a hillside
groundwater flow system located east of the knoll; and another shallow system contained
in the Weber River alluvium to the east. Figure 1-4 presents a topographic cross-section of
OU2 and illustrates the location of the groundwater flow systems.
The degree of hydrogeologic continuity between these unconfined systems is difficult to
-define because of the complex nature of the geology observed in the off-Base area. This is
further complicated because of landslides along the steep escarpment between HAFB and
the Weber River Valley. However, the distribution of major ions in groundwater flowing
through each system shows similarities between the three systems. The major ion data
suggests that these systems may differ from the flow system in which the background test
wells are screened.
Depth to groundwater in the shallow system is generally less than 10 feet below ground
surface in the off-Base area and 20 feet below ground surface in the on-Base area. The depth
to the hillside groundwater ranges from 35 to 70 feet below ground surface. The depth to
groundwater in the Weber River alluvium ranges from 5 to 15 feet below ground surface.
The saturated thickness of these shallow unconfined groundwater systems is generally less
than 30 feet.
SLC\RME70158.FaflNAL\RODRNALDOC 3-1
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
The highest levels of contamination are in the shallow groundwater flow system.
Contamination has been found historically in the hillside system. However, flow patterns
have changed since the Davis-Weber Canal was relined through the area of OU2.
Monitoring since May 1993 has detected no contaminants in the hillside system. Low level
contamination has been found in the Weber River alluvium groundwater flow system as of
1986.
Based on the State of Utah Groundwater Quality Classifications, the shallow groundwater,
hillside, and Weber River alluvium systems would likely be Class n Drinking Water
Quality Groundwater. The classification is based on ambient total dissolved solids (TDS)
concentrations ranging between 500 and 3,000 milligrams per liter (mg/1). Figure 3-1
presents the potentiometric surface and flow direction of the shallow groundwater
monitoring wells. Groundwater flow in the shallow system is to north and northeast.
Seeps and springs occur along the hillside and are fed by groundwater from the shallow
and hillside systems where the groundwater surface intersects the land surface. Discharge
rates vary seasonally with groundwater levels, some are dry in summer and fall.
3.2 Nature and Extent of Contamination
Environmental samples were taken from soil, sediment, groundwater, surface water, and
air at the site. Table 3-1 lists the chemicals detected in soil, surface water, and groundwater
at OU2. Inorganic chemicals on Table 3-1 include only those that appeared elevated above
background based on statistical comparisons. Based on investigative efforts, the source of
contamination at OU2 is the former disposal trenches (Chemical Disposal Pit 3). Perimeter
Road along the northeastern part of HAFB has been investigated and found to be free of
contamination except in those areas currently being addressed as part of other OUs.
Accumulations of a dense, non-aqueous phase liquid (DNAPL) occur on-Base and in the
shallow groundwater flow system in the vicinity of the former disposal pits. The DNAPL
layer is composed primarily of a mixture of several chlorinated and non-chlorinated
solvents and a lesser amount of co-solved oil and grease. The solvent fraction is
approximately 75 percent TCE with smaller percentages of TCA, PCE, methylene chloride,
toluene, and Freon TF. Two separate accumulations of DNAPL have been identified and
are depicted in Figure 3-2. The accumulations occur within depressions in the surface of a
relatively low permeability clay layer. It is estimated that there are approximately 5,685
gallons of DNAPL as residual in the vadose zone and 110,000 gallons of free-phase DNAPL
saturating sands and clays at the site.
Volatile Organic Compounds (VOCs) predominate among the contaminants found in all of
the media. The principal VOCs include trichloroethylene (TCE), tetrachloroethylene (PCE),
and 1,1,1-trichloroethane (TCA). Less common and widespread VOCs include 1,2
dichloroethene, methylene chloride, and toluene. VOCs are in the highest concentrations in
the vicinity of the former disposal pits and decrease with distance laterally from the pit
area. Soil samples in the immediate vicinity of the pit have concentrations of VOCs in the
parts per million range. Groundwater samples in the source area near the DNAPL exhibit
concentrations in the parts per million range, approaching the solubility limits of the
principal VOCs. Concentrations drop rapidly to the parts per billion range toward the
South Weber Valley.
SLC\RME70158H*nNAL\flODRNALDOC 3-2
-------
4540
U2-W1
.15'11. GO
MOM i ion if jr. WELL LOCAfion
spnino LOCAnon
onounov/AiEn FLOV/ DIRECTION
POTENTIOMETRIC SURFACE FOR
SHALLOW OU2 WELLS. AUG 1905
t> tllJt ?. MM Air forc» Oil*, UltM J
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 3-1
Chemical Contaminants Detected in Soil, Surface Water, and
Groundwater
Volatile Organic Compounds (SW8240 and SW8010)
Acetone Carbon disulfide
2-Butanone (MEK) 1,2-Dichloroethene
Carbon tetrachloride 1,1-Dichloroethene
Chloroform 1,2-Dichloroethane
Chlorobenzene 1,1-Dichlorethane
Ethylbenzene 1,1,2-TricWorotrifluoroethane
2-Hexanone Trichloroethylene
Methylene Chloride Trichlorofluoromethane
4-Methyl-2-pentanone (MIBK) Tetrachloroethene
1,1,2-Trichloroethane Toluene
1,1/1-Trichloroethane Xylenes
Semivolatile Organic Compounds (SW8270, SW8310, and SW8040)
Butylbenzylphthalate N-Nitrosodiphenylamine
1,2-Dichlorobenzene Naphthalene
1,3-Dichlorobenzene Phenanthrene
1,4-Dichlorobenzene Phenol
2-Methylnaphthalene bis(2-ethylhexyl)phthalate
Pyridine Benzo(a)anthracene
2-Methylphenol (o-cresol) Benzo(a)pyrene
4-Methylphenol (p-cresol) Benzo(b)fluoranthene
2-Nitrophenol Benzo(k)fluoranthene
1,2,4-Trichlorobenzene Chrysene
Benzole Acid Dibenzo(a/h)anthracene
Benzyl alcohol Ethyl methacrylate
Dibutylphthalate Indeno(l/2,3-cd)pyrene
Diethylphthalate 2,3/4,6-Tetrachlorophenol
Di-n-ocylphthalate Styrene
Isophorone
SLaRME70158.FO^^NAL^ROOR^4ALOOC 3-4
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9/17/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 3-1 (continued)
Pesticides (SW8080)
4,4-DDD
4,4-DDE
4,4-DDT
Aldrin
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan Sulfate
Endrin
Endrin Aldehyde
Heptachlor
Heptachlor epoxide
alpha-BHC
beta-BHC
delta-BHC
gamma-BHC (Lindane)
Methoxychlor
Inorganic Compounds
Aluminum
Arsenic
Beryllium
Calcium
Chloride
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Nitrate/Nitrite
Potassium
Silicon
Sodium
Strontium
Sulfate
Vanadium
Zinc
SLC\RME70158.R>RNM\RODFtNALDOC
3-5
-------
APPROXIMATE LOCATION
OF FORMER CHEMICAL
DISPOSAL TRENCHES
NOTE:
ADAPTED FROM "REMEDIAL INVESTIGATION
REPORT FOR OPERABLE UNIT 2.
VOLUME 1. FIGURE 4-11,
HILL AIR FORCE BASE. UTAH JULY 1992.
50 100
SCALE IN FEET
150
LEGEND
DENSE NONAOUEOUS
PHASE LIQUID (DNAPU
HILL AIR FORCE BASE
BOUNDARY
Figure 3-2
LOCATION OF DNAPL POOLS
OCMTKM urtt 2. MJ A* Fact B«M. Utan
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
TCE is used as the primary indicator chemical for the extent of contamination at OU2,
particularly in groundwater, because it is the most widespread. Other chemical
contaminants exist within the extent of the TCE contamination. Groundwater samples
obtained from on-Base monitoring wells installed in the shallow groundwater flow system
were found to contain high levels of TCE, TCA, and PCE. Maximum concentrations of
chemicals dissolved in groundwater include: 890,000 |ig/l of TCE, 33,000 |iig/l of TCA, and
9,800 jig/1 of PCE. Other VOCs found included 460 jig/1 of 1,2-dichloroethene (DCE),
18,000 ng/1 of methylene chloride, 5,500 |ig/l of 1,1,2-trichlorotrifluoroethane (Freon TF),
and 4,400 ^g/1 of toluene. Figures 3-3,3-4, and 3-5 present the extent of TCE, PCE, and
TCA contamination, respectively, in groundwater at OU2.
Groundwater samples from off-Base wells installed in the shallow groundwater flow
system also contained TCE; a maximum concentration of 6,300 ^g/1 was detected. In
addition to TCE, both TCA (380 ^ig/1) and PCE (25 ^ig/1) were detected. Samples from the
hillside groundwater flow system did not contain detectable concentrations of VOCs. Wells
installed in the hillside system are apparently out of the principal migration pathway of
organic contaminants towards the off-Base area. However, groundwater samples from
monitoring wells completed in the Weber River alluvium flow system contained low levels
of the chlorinated solvents known to be present from past waste disposal activities. A
single non-chlorinated VOC (xylene) was found at a concentration below the reporting
limit
A variety of pesticides were detected. Most pesticides occurred in soil media throughout
the area at relatively low concentrations (below health-based levels) and are believed to be
related to agricultural and pest-control application activities rather than waste disposal.
Semi-volatile compounds (SVOCs) were detected, but generally at levels at or below
reporting limits. No PCBs were detected. Some metals concentrations are elevated above
background concentrations in soils near the pits. Some of the data indicate levels of
inorganics slightly above background in groundwater, but the available information
suggests these are artificially elevated due to hydrogeological and well construction issues.
Surface water features in the OU2 area include springs and seeps located on the hillside
between HAFB and the South Weber Valley. Several springs and seeps fed by groundwater
occur along the hillside north of the Source Area. Discharge rates fluctuate with climatic
and seasonal changes. Figures 3-3 through 3-5 present the location of canals, springs, and
seeps. Most of the same contaminants found in groundwater are found in the seeps and
springs.
The Davis-Weber Canal and the Bambrough Canal, two constructed irrigation canals, are
surface water features within OU2. These canals are designated Class 4 waters (water for
agricultural uses) by the Utah Division of Water Quality. The Davis-Weber Canal is
situated above the shallow groundwater flow systems and is lined with concrete. No
springs flow into the canal in the vicinity of OU2. The Davis-Weber Canal appears to be
hydraulically isolated from potential sources of contaminants. No contaminants
attributable to OU2 have been detected.
Ethylbenzene, toluene, and xylene were detected in the Bambrough Canal at concentrations
less than the reporting limit (1 |ig/l) and are not believed to be site related. SVOCs detected
in the Bambrough Canal were below reporting limits and some pesticides were detected
slightly above reporting limits. One sample of unfiltered water from the Bambrough Canal
SLC\RME70158.FO\F1NAL\RODFINALDOC 3-7
-------
P:/«M6a2/E t/DRAWINOS/Fl03-2.DON
FORMER CHEMICAL
DISPOSAL TRENCHES
SCALE IN FEET
Figure 3-3
DELINEATION OF TCE PLUME
/ OpcrrtM* Unit 2. MM A* Forc« B»M. Ui«n
-------
Figure 3-4
DELINEATION OF PCE PLUME
Operabte Urti 2. Hit Air Fore* Base. Uuft
-------
P:/n8602/E Vt>flAWINQS/FlO3»4.OGN
I2-3G 1...
SCALE IN FEET
Figure 3-5
DELINEATION OF TCA PLUME
Unit 2. Mil A* Forc« Btsa. Uitfi
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
contained a maximum of 0.12 mg/1 of chromium, which exceeded the Utah Surface Water
Quality Standard for Class 4 waters of 0.10 mg/1). All other inorganic constituents were
below Utah Class 4 standards. None of these contaminants are believed to be site related.
Air emissions were based on flux chamber measurements in the source area where VOCs in
soil gas exhibited the highest concentrations. The maximum measured flux concentration
was reported for TCE (8.4 |ig/m3); TCA (0.7 ^g/m3); PCE (3.2 Hg/m3), and methylene
chloride (0.48
3.3 Contaminant Transport
Populations and environmental receptors that could be affected, if exposed, include HAFB
personnel, off-Base residents north of OU2, future on-Base residents, and plants and
animals in the vicinity. The VOCs at OU2 are soluble in water and volatilize into air and
the likeliest transport pathways are in water and air. The highest concentrations of
contaminants occur on-Base in the vicinity of the former disposal pits. The DNAPL is a
concentrated source for VOCs. Potential routes of contaminant transport by groundwater
include infiltration through contaminated soils in the source area to the shallow
groundwater, partitioning of VOCs from the DNAPL into groundwater and then transport
of contaminants towards off-Base areas including seeps and springs. There are also
potential volatilization pathways that include volatilization from contaminated soils to air
or soil gas, volatilization from contaminated groundwater to soil gas, and volatilization
from seeps and springs.
Current on-Base land use at OU2 is restricted. The OU2 on-Base area has not been used for
military activity other than the documented waste disposal and is not used for any
recurring HAFB function. The main activity is the Source Recovery System (SRS) used to
recover the DNAPL in the subsurface. Consequently, HAFB personnel are not expected to
encounter site-related contamination on a routine basis. Shallow groundwater in the area is
not used as a domestic water source, edible plants are not cultivated, and the area is not
subject to cattle grazing. Therefore, current exposures to site-related contamination within
the OU2 on-Base area are not anticipated.
Contaminant migration in groundwater is the most significant pathway. The available
information regarding operation of the waste disposal trenches indicates that spent liquid
chlorinated organic solvents were poured into unlined earthen trenches. The liquid
solvents infiltrated through the unsaturated soil to the water table. The solvents continued
migrating downward as a DNAPL plume because their specific gravity is greater than
water. Downward migration was impeded when the DNAPL reached the Alpine
Formation, a low permeability layer composed mostly of silty clay with occasional, thin
silty sand lenses. Continued transport of the contaminants occurred as dissolved
constituents in groundwater. Some of the shallow groundwater at OU2 discharges to
springs and seeps located on the hillside east of Perimeter Road. Several of these springs
and seeps are contaminated with the same compounds found in contaminated shallow
groundwater. Off-Base transport of site-related chemicals in groundwater has occurred as
far as South Weber Drive.
Current land use in off-Base areas is low-density residential development and agriculture.
Agricultural land uses include grazing cattle and sheep, in addition to growing alfalfa. Off-
SLC\RME70158.FOFINAL\ROOFINAL 3-11
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Base residents rely on municipal water for their domestic supply. Shallow groundwater is
not used as a source of drinking water in the area, but has been used for irrigation and cattle
watering. Alternate water supplies have been provided or treatment units installed at
springs to address this pathway to prevent exposures. The Summary of Site Risks
(Section 4) discusses the potential exposures in more detail.
Surface soils at OU2 contain elevated inorganic and pesticide constituents in concentrations
greater than background. These constituents may be carried by wind-borne dust. The air
pathway for VOC contaminant transport at OU2 is through direct volatilization and vapor
migration from the soils to the atmosphere. Contaminants from OU2 have been found in
soil gas outside of the former Chemical Disposal Pit 3 area.
Based on information collected to date regarding OU2, effects of exposures to nearby
ecosystems are expected to be minimal. Details regarding the population and
environmental receptors that could be affected are discussed in Section 4, which
summarizes the findings of the human health and environmental assessments.
SLC\RME70158.FO\FlNAL\RODFiNAL 3-12
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9/17/96 FINAL RECORD CF DECISION FOR OPERABLE UNIT 2
4. SUMMARY OF SITE RISKS
A Baseline Risk Assessment (BRA) was prepared for OU2 to evaluate potential health and
environmental effects caused by actual or potential releases of and exposure to OU2-related
chemicals under current and hypothetical future conditions. The risk assessment identifies
the contaminants of concern (COCs), current and future exposure pathways for humans
and environmental receptors, and the probability of adverse effects resulting from
exposure. Detailed descriptions of the risk assessment are available in the March 1992
Baseline Risk Assessment and April 1994 Final Addendum to the Remedial Investigation Report for
Operable Unit 2, Site WP07, SS21. Assessment of risk to human health is summarized for
each of the four basic components of the risk assessment: identification of chemicals of
concern, exposure assessment, toxicity assessment, and risk characterization.
4.1 Human Health Risks
4.1.1 Chemicals of Potential Concern
Chemicals of potential concern (COPCs) are "chemicals that are potentially site-related and
whose data are of sufficient quality for use in the quantitative risk assessment (EPA, 1989)."
All data of acceptable quality from the Phase I and Phase n IRP investigations and both
phases of the remedial investigation were used to identify COPCs. Detailed description of
the screening and identification process and criteria are described in the risk assessment
documents. Criteria used to select COPCs followed EPA guidance (1989). In addition,
chemicals were screened against conservative risk-based concentrations based on calculated
preliminary remediation goals for a residential exposure scenario. Chemicals contributing
less than 1.0 percent of the relative carcinogenic risk, and less than 1.0 percent of the relative
noncarcinogenic risk were eliminated. The COPCs associated with air were determined
through modeling to identify those most mobile and posing the greatest potential
carcinogenic and noncarcinogenic effects.
Table 4-1 lists the media-specific COPCs and associated exposure concentration data used
for risk characterization.
The COPC list was further refined into a list of chemicals of concern (COC) which are
chemicals that pose the greatest risk or exceed regulatory standards. Table 4-2 lists the
COCs. A detailed description of the process used to identify COCs is presented in the Final
Addendum to the Feasibility Study (February 1994).
SLORME70158.FaflNAL\ROOF1NALDOC 4-1
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9/17/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-1
Media-Specific Chemicals of Potential Concern and
Concentrations Used in Risk Assessment Addendum
Chemical
Maximum
Concentration
95% Upper
Confidence Limit
SURFACE SOILS
Organics mg/kg
Dieldrin
9.4
0.005
Inorganics (mg/kg)
Beryllium
Lead
49
83
8.66
47.57
SUBSURFACE SOILS
Organics (mg/kg)
Tetrachloroethene
Trichloroethene
Aldrin
Dieldrin
bis(2-ethylhexyl)phthalate
200
880
0.0065
0.013
24
7.68
43.6
0.0036
0.0067
12.159
Inorganics (mg/kg)
NONE
SITE-WIDE GROUNDWATER
Organics (mg/L)
Trichloroethene
Tetrachloroethene
Methylene chloride
Dibenzo(a,h)anthracene
Benzo(a)pyrene
Dieldrin
bis(2-ethylhexyl)phthalate
beta-BHC
gamma-BHC
Aldrin
Heptachlor
Heptachlor epoxide
alpha-BHC
11,1,1-Trichloroethane
1,2-Dichloroethene
Toluene
890,000
9,800
18,000
2.65
2.65
0.088
52
0.4
0.48
0.024
0.063
0.026
0.023
33,000
500
4,400
62,270
1310
1,640
2.1
2.1
4.98E-02
16.7
0.3
0.3
1.55E-02
3.62E-02
1.69E-02
1.95E-02
31,950
119.7
445
SLC\RME70158.FO\F1NAL\ROOF1NALDOC
4-2
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9/17/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-1
(Continued)
Chemical
Maximum
Concentration
95 % Upper
Confidence Limit
Inorganics (mg/L)
Nitrate-Nitrite
Nickel
Chromium
38,000
2,700
11,450
2,750
565.4
1,707.4
OFFSITE GROUNDWATER
Organics (mg/L)
1,1/1-Trichloroethane
1,2-Dichloroethene
Aldrin
alpha-BHC
bis(2-ethylhexyl)phthalate
delta-BHC
^ieldrin
gamma-BHC
rleptachlor
fieptachlor epoxide
Vlethylene chloride
Tetrachloroethene
Toluene
Trichloroethene
Nitrate-Nitrite
Nickel
Chromium
3.85
0.12
0.011
0.0017
2.4
0.02
0.02
0.014
0.013
0.014
2.0
1.1
1.4
53
38,000
2,700
11,480
1
0.12
0.013
0.02
3
0.02
0.02
0.015
0.016
0.017
0.7
0.4
0.6
1.9
2,750
565
1.710
AIR -Ambient'
Organics (mg/m5)
1,1/1-Trichloroethene
Methylene chloride
Tetrachloroethene
Trichloroethene
3.00E-08
1.90E-08
5.10E-09
9.67E-07
3.00E-08
1.90E-08
5.10E-09
9.67E-07
'Fugitive dust concentrations in air are presented in Appendix N-2 of the Final RI Addendum.
SLC\RME70158.R>RNAL\RODFINALDOC
4-3
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9/17/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-2
Chemicals of Concern
Ground and Surface Water
1,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
1,1,1-Trichloroethane
Trichloroethene
Toluene
beta-BHC (in source area only)
gamma-BHC (Lindane) (in source area only)
Soil and Sediment
Tetrachloroethene
Trichloroethene
4.1.2 Exposure Assessment
The exposure assessment identifies:
receptors (people) that could potentially be exposed to media containing COPCs
by looking at land use both onsite and offsite (contaminants may have migrated
from the site,) under current and hypothetical future conditions
pathways of exposure (such as ingestion, inhalation, and dermal contact)
how much exposure could occur (exposure point concentrations, frequency, and
duration of exposure, the amount of media contacted)
Table 4-3 presents a matrix of potentially exposed populations and relevant exposure
pathways. The following describes the exposure pathways in more detail.
4.1.2.1 Current Offsite Residential Exposure Scenario
The current land use in the off-Base areas immediately north and east of OU2 consists of
small farms and scattered residential homes. The land area immediately east of the HAFB
boundary is owned by the Davis-Weber Canal Company and private land owners. Portions
of these areas are occasionally used as rangeland for horse, cattle, and sheep grazing.
Farther east, beyond the Davis-Weber Canal, land uses consist of alfalfa fields intermixed
with undeveloped rangeland, and residences (some with vegetable gardens).
Pathways for both child and adult receptors include the following:
inhalation of volatile compounds in ambient air
inhalation of contaminated fugitive dust from the site in ambient air
ingestion of fruits and vegetables irrigated with contaminated groundwater
ingestion of meat and dairy products from animals fed contaminated water or
contaminated feed
SlC\RME70158.raRNAL\RODRNALDOC
4-4
-------
Table 4-3
Matrix of Potentially Exposed Populations and Relevant Exposure Pathways
Potentially Exposed
Populations
Offeite Residents
- Current Exposure
- Future F.xpusiire
Future Omile
Residents
Future Oiisile
Construction Workers
Inhalation of
Ambient Air
V
V
V
V
logestlonof
Drinking
Water
X
V
X
Dermal
Contact with
Residential
Water
X
V
V
X
Inhalation of
Vapor Phase
Chemicals
From
RtildenlUI
Wain
X
v
V
X
Ingestion of
Fruits and
Vegetables
V
V
X
Ingestion of
Meat and
Dairy
;J
v
X
Ingeillon of
Flth
X
V
V
X
Incidental
Ingeillonof
Soil «nd/or
Sediimnl
X
X
>/
V
Dermal
Contact with
Soil and/or
Sediment
X
X
V
V
Inhalation of
Vapors at the
Source Area
X
X
X
V
Note: A "check mark" (V) indicates that the exposure pathway applies.
An "X" indicates that the exposure pathway does not apply.
SLC\RME70158 FCAFINALNROOFINAL DOC
45
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3/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Air emissions containing COPCs were estimated using an emission rate equation applicable
to the volatilization of organic compounds from buried contamination. Soil exposure point
concentrations were used to develop the fugitive dust concentration of inorganic COPCs.
Models to estimate fruit and vegetable uptake used the same groundwater exposure point
concentrations which were used to develop the route-specific contribution of COPCs.
Groundwater exposure point concentrations were also used in a model to estimate beef and
milk uptake.
Exposure parameters used for the current offsite receptors were obtained from EPA risk
assessment guidance and were used when available and applicable. Site-specific and
chemical-specific values were used when available data justified their use. These included,
for the future onsite construction worker scenario, an ambient dust level of 486 |ig/m3. For
soil adherence to skin, a value of 1 mg/cm3 was used versus the value of 2.77 mg/cm3
default value. For the showering pathway, inhalation of VOCs from water was calculated
only for those COPCs with a volatilization factor greater than 0.5 liters per cubic meter, per
EPA guidance.
4.1.2.2 Future Offsite Residential Exposure Scenario
Based on population demographics for Davis County, the population increased by
22 percent from 1980 to 1987 (146,540 to 179,000). Other areas proximate to HAFB saw
population increases; adjacent Weber County population experienced an 8.5 percent
increase. The City of Ogden also experienced slight population growth.
The most likely future changes in land use in the area include increases in residential
housing and decreased agricultural activities. New residents will most likely be connected
to the municipal water supply, but could use shallow wells and drains for lawn and garden
irrigation. New residents may also elect to install shallow groundwater wells even though
higher quality water is readily available from other sources (i.e., municipal sources and
deeper aquifers).
Exposure parameters used for the future offsite receptors were obtained from risk
assessment guidance and were used when available and applicable. Site-specific and
chemical-specific values were used when available data justified their use; otherwise,
conservative default values were substituted.
Pathways for child and adult receptors include the following:
inhalation of volatile compounds in ambient air
inhalation of contaminated fugitive dust from the site in ambient air
ingestion of contaminated drinking water
dermal contact with contaminated water while showering and dish washing
inhalation of volatile compounds while showering, dish washing, clothes
washing, and use of toilets
ingestion of fish in contact with surface water contaminated via groundwater
migration
ingestion of fruits and vegetables irrigated with contaminated groundwater
ingestion of meat and dairy products from animals fed contaminated water or
contaminated feed
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The site-wide list of groundwater COPCs were used as the basis for calculating exposure
point concentrations for the domestic water use scenarios to estimate the risks associated
with future offsite residential exposures. Air emissions containing COPCs were estimated
using an emission rate equation applicable to the volatilization of organic compounds from
buried contamination. Soil exposure point concentrations were used to develop the fugitive
dust concentration of inorganic COPCs.
The 95 percent upper confidence level of the mean concentrations of COPCs were used to
determine exposure point concentrations to estimate the intake of COPCs through direct
ingestion of and dermal contact with groundwater during in-home use (e.g., showering).
Use of contaminated water for bathing, showering, dish washing, clothes washing, and use
of toilets may contribute to concentrations of volatile chemicals in the indoor air. A shower
volatilization model was used to predict the concentration of volatiles released to the indoor
air.
Models to estimate fruit and vegetable uptake used the same groundwater exposure point
concentrations which were used to develop the route-specific contribution of COPCs.
4.1.2.3 Future Onsite Residential Exposure Scenario
Residential development is-not a likelihood in the on-Base areas of OU2. However, to
provide a conservative assessment of the potential risks associated with OU2, health risks
based on a future onsite residential development were evaluated. The future potential
exposure pathways associated with unrestricted, onsite residential land use include the
following:
inhalation of VOCs in ambient air
inhalation of contaminated fugitive dust from the site in ambient air
ingestion of contaminated drinking water
dermal contact with contaminated water while showering and dish washing
inhalation of VOCs while showering, dish washing, clothes washing, and use of
toilets
ingestion of fish in contact with surface water contaminated via groundwater
migration
ingestion of fruits and vegetables irrigated with contaminated groundwater
ingestion of meat and dairy products from animals fed contaminated water or
contaminated feed
skin contact with and incidental ingestion of contaminated sediments
skin contact with and incidental ingestion of contaminated soils
Assumptions and exposure point concentrations associated with all of the above exposure
scenarios, except for the first one and the last two, were identical in evaluation to those
considered for future offsite residents. Exposure point concentrations associated with
inhalation exposures to VOCs were estimated using soil gas survey results and assuming
that the emissions are trapped in the first 2 meters of the atmosphere. Exposure point
concentrations associated with exposure to soil were based on the assumption that
subsurface soil, when brought to the surface, would be available for contact through
SIOAME701S8.FORNAL\ROORNALOOC 4-7
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
incidental ingestion and dermal contact. The concentrations of COPCs were used to derive
the exposure point concentrations for both skin contact and incidental ingestion. In
addition, future onsite residents could face exposure to surface and subsurface soil (brought
to the surface as a result of excavation) through inhalation of fugitive dust.
4.1.2.4 Future Onsite Worker Scenario
If development occurs at OU2 in the absence of remediation, onsite construction workers
could be exposed to site-related chemicals. Exposure pathways effecting workers engaged
in construction activities include:
inhalation of volatile compounds in ambient air
inhalation of contaminated fugitive dust from the site in ambient air
inhalation of VOCs close to the source
skin contact with and incidental ingestion of contaminated sediments
skin contact with and incidental ingestion of contaminated soil
As with the future onsite residential setting, exposure point concentrations associated with
inhalation exposures to VOCs were estimated using soil gas survey results similarly to the
future onsite resident. The concentrations of COPCs were used to derive the exposure point
concentrations for both skin contact and incidental ingestion. The exposure point
concentrations associated with exposure to soil were based on the assumption that
subsurface soil, when brought to the surface, would be available for contact through
incidental ingestion and dermal contact. Measured concentrations of COPCs were used to
derive the exposure point concentrations for both skin contact and incidental ingestion. In
addition, future onsite workers could face exposure to surface and subsurface soil (brought
to the surface as a result of excavation) through inhalation of fugitive dust.
4.1.3 Toxicity Assessment
Contaminants may have carcinogenic (cancer-causing) effects or noncarcinogenic/systemic
effects. Exposure to some of the chemicals detected at OU2 could potentially result in both
types of effects. For carcinogens, it is assumed any amount of exposure to a carcinogenic
chemical poses a potential for generating a carcinogenic response in the exposed organism.
Noncarcinogenic or systemic effects include a variety of toxicological end points and may
include effects on specific organs or systems, such as the kidney, liver, lungs, etc. Threshold
levels generally exist for noncarcinogenic effects, i.e., a dose exceeding a certain level must
be reached before health effects are observed. No adverse effects are assumed for doses
below the threshold.
Cancer potency factors (CPFs), or Slope Factors (SFs) are used to provide conservative
estimates of excess lifetime cancer risks associated with exposure to potentially carcinogenic
chemicals. Slope Factors, which are expressed in units of (mg/kg-day)"1, are multiplied by
the estimated intake of a potential carcinogen, in mg/kg-day, to provide an upper-bound
estimate of the excess lifetime cancer risk associated with exposure at the intake level. The
term "upper bound" reflects the conservative estimate of the risks calculated from the SF.
Use of this approach makes underestimation of the actual cancer risk unlikely. Slope factors
are derived from the results of human epidemiological studies or chronic animal bioassays
SIORME70158.FO\F1NAL\RODFINALDOC 4-8
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to which animal-to-human extrapolation and uncertainty factors have been applied (for
example, to account for the use of animal data to predict effects on humans).
Reference doses (RfDs) are used to indicate the potential for adverse health effects from
exposure to chemicals causing noncarcinogenic effects. RfDs, which are expressed in units
of mg/kg-day, are estimated threshold levels for daily exposure below which exposure is
considered safe for humans, including sensitive individuals. Estimated intakes of COPCs
from environmental media (for example, the amount of a COPC ingested from
contaminated drinking water) can be compared to the RfD. RfDs are derived from human
epidemiological studies or animal studies to which uncertainty factors have been applied
(for example, to account for the use of animal data to predict effects on humans).
Slope Factors and RfDs used in conjunction with chemical intake to estimate the potential
for adverse health effects for the COPCs, are presented in Table 4-4. Slope factors and RfDs
are specific to the route of exposure; for example, oral SFs are used to evaluate risk through
ingestion of a carcinogenic COPC.
Oral SFs and RfDs are not available for all COPCs identified at OU2. When data are
limited, toxicity values are sometimes derived from alternate data. The alternate data
include unverified RfDs for TCE provided in "Drinking Water Regulations and Health
Advisories" published by EPA. RfDs for DCE and nickel have not been verified but are
listed in the EPA's Integrated Risk Information System (IRIS).
4.2 Summary of Risk Characterization
Carcinogenic and noncarcinogenic risks were calculated for each of the exposure pathways
for the potential contaminants of concern and compared to acceptable levels of risk. For
carcinogens, risks are estimated as the incremental probability of an individual developing
cancer over a lifetime as a result of exposure to the carcinogen. Risks are probabilities that
are generally expressed in exponential form. An excess lifetime cancer risk of 1 x 10*6
indicates that an individual has a one-in-1 million additional chance of developing cancer
as a result of site-related exposure to a carcinogen over a 70-year lifetime under specific
exposure conditions at OU2.
To address the range of exposures that may occur at the present time and in the future, both
average and reasonable maximum exposures (RME) were considered. Inclusion of both
average and RME exposures allows risks to be estimated for the upper-bound exposure
situation and the more typical or average exposure. The resulting risk estimates then
present a range of possible risks based on the range of possible exposure conditions.
The National Contingency Plan (NCP) uses 1 x 10"4 to 1 x 10"6 as a range within which the
EPA strives to manage risks as part of a Superfund cleanup. Although waste management
strategies achieving reductions in site risks anywhere within the risk range may be deemed
acceptable by the EPA risk manager, the NCP expresses a preference for cleanups achieving
the more protective end of the risk range (for example, 1 x 10*). Risks in the 10"* to 10* range
may be significant and remedial action may be warranted. Those risks exceeding a 10"4 are
significant and remedial action is required. The use of the terms "significant", "potentially
significant", and "insignificant" are not meant to imply acceptability. They are intended
only to provide perspective. A specific risk estimate less than 1 x Iff4 may be considered
unacceptable based on site-specific conditions, including any remaining uncertainties about
the nature and extent of contamination and associated risks.
SLDRME70158.F(>F1NAL\ROORNALOCX: 4-9
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FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-4
Toxicity Values for Chemicals of Potential Concern
Compound
1,1,1 -Trichloroethane
1,2-Dichloroethene
Aldrin
alpha-BHC
Benzo(a)pyrene
Beryllium
beta-BHC
bis(2-Ethylhexyl)-
phthalate
Chromium
delta-BHC
Dibenzo(a,h)-
anthracene
Dieldrin
gamma-BHC
ieptachlor
Heptachlor epoxide
Lead
Methy lene chloride
Nickel
Nitrate-Nitrite(b)
'henanthrene
Silicon
Sulfate
Tetrachloroethene
Toluene
rrichloroethene
EPA
Class
D
B2
B2
B2
B2
C
B2
-
D
B2
B2
B2/C
B2
B2
B2
B2
A
D
B2/C
D
B2/C
Chronic
OralRfD
mg/kg/day
9.00E-02 (H)
l.OOE-02 (H)
3.00E-05 (I)
5.00E-03 (I)
2.00E-02 (I)
l.OOE+00 (J)
5.00E-05 (I)
3.00E-04 (I)
5.00E-04 (I)
1.30E-05 (I)
6.00E-02 (I)
2.00E-02 (1)
l.OOE-01
l.OOE-02 (I)
2.00E-01 (I)
Chronic
Dermal
RfD(a)
mg/kg/day
4.50E-03
5.00E-04
1.50E-06
250E-04
1.00E-02(a)
5.00E-02
2.50E-05(a)
2.98E-04(a)
3.00E-04(a)
7.80E-06(a)
3.00E-03
l.OOE-03
5.00E-03
9.80E-03(a)
l.OOE-02
Chronic
Inhalation
RfC
mg/m3
l.OOE+03 (H)
3.00E+03 (H)
_
4.00E+02 (I)
OralSF
l/
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9/17/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-4 (Continued)
Compound
,1,1-Trichloroethane
1,2-Dichloroethene
Aldrin
alpha-BHC
3enzo(a)pyrene
Beryllium
beta-BHC
bis(2-Ethylhexyl)-phthalate
Chromium
delta-BHC
}ibenzo(a,h)-anthracene
Dieldrin
gamma-BHC
Heptachlor
ieptachlor epoxide
-ead
Vlethylene chloride
Nickel
Nitrate-Nitrite
Phenanthrene
Silicon
Sulfate
Fetrachloroethene
Toluene
Frichloroethene
EPA
Class
D
B2
B2
B2
B2
C
B2
-
D
B2
B2
B2/C
B2
B2
B2
B2
A
D
B2/C
D
B2/C
Subchronic
OralRfD
mg/kg/day
9.00E-01 (H)
l.OOE-01 (H)
3.00E-05 (H)
_
5.00E-03 (H)
2.00E-02 (H)
l.OOE+01 (H)
5.00E-05 (H)
3.00E-03 (H)
5.00E-04 (H)
1.30E-05 (H)
6.00E-02 (H)
2.00E-02 (H)
_
l.OOE-01
2.00E+00 (H)
Subchronic
Dermal RfD(a)
mg/kg/day
4.50E-02
5.00E-03
1.50E-06
2.50E-04
_
1.40E-02(a)
5.00E-01
_
_
2.50E-05O
2.98E-03C)
3.00E-04(*)
7.80E-06H
_
3.00E-03
l.OOE-03
9.50E-02(*)
l.OOE-01
Subchronic
Inhalation Rf C
mg/m3
l.OOE+00 (H)
_
_
.
_
~_
-.
_
_
3.00E+03 (H)
_
«.
2.00E+00 (H)
(a) Dermal values were derived from oral values according to guidance in Risk Assessment Guidance for Superfund
(EPA, 1989a).
(b) Toxicity values for Nitrate used as surrogate values for Nitrate-Nitrite.
(*) Derived from gastro-intestinal absorption values according to guidance in Risk Assessment Guidance for Superfund
(EPA, 1989a.)
SF Cancer slope factor (risk per milligram pollutant per kilogram body weight per day)
RfD Reference dose chronic (milligrams pollutant per kilogram body weight per day)
RfC Reference concentration
(H) HEAST,FY1993
(I) IRIS on line search (2/25/94) (EPA, 1991a)
(E) Slope Factor obtained from Superfund Health Risk Technical Support Center (EPA, 11/93).
(E)1 EPA 10/93
(S) The RfD for endsulfan was used as a surrogate for endosulfan sulfate (Ito, 1975).
(Q Values calculated using the "Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic
Hydrocarbons," (EPA, 1993).
SLDRME70158.FOF)NAL\ROOF1NALOOC
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over
a specified time period (for example, a lifetime) with a RfD derived for a similar exposure
period. The ratio of a single substance exposure level over a specified time to a reference
dose for that substance derived from a similar exposure period is called a hazard quotient
(HQ). The HQ is the ratio of the chronic daily intake (GDI) to the RfD. The GDI and RfD
are expressed in the same units and represent the same exposure period (that is, chronic,
subchronic, or short-term).
If the GDI (exposure) is greater than the RfD, the HQ will be greater than one. An HQ
greater than one indicates the potential for an adverse noncarcinogenic health effect from
exposure to the chemical.
A Hazard Index (HI) is generated by adding the simultaneous subthreshold exposures of
several chemicals that could result in an adverse health effect. HQs are added for all
COPCs that effect the same target organ or system (for example, the liver or respiratory
system) within a medium or across all media to which a given population may reasonably
be exposed. If the HI for each toxic end point exceeds one, the potential for an adverse
noncarcinogenic health effect from exposure to the medium is indicated.
The following describes the results of the risk characterization for each exposure scenario
discussed above. Table 4-5 identifies key chemicals and exposure pathways associated with
the potential for carcinogenic risks; Table 4-6 identifies key chemicals and exposure
pathways associated with the potential for noncarcinogenic health effects. Tables 4-7 and
4-8 summarize the cumulative average and reasonable maximum carcinogenic and non-
carcinogenic risks, respectively.
The carcinogenic and non-carcinogenic risk characterization for OU2 indicates that under
realistic worst-case and most probable exposure scenarios, risks associated with current
exposure pathways are mostly "insignificant". For the future construction worker, risks are
potentially significant in the low probability range for carcinogens and non-carcinogenic
effects are unlikely.
Potential risks are indicated for the future offsite residential exposure scenario:
For adults, the estimated excess lifetime cancer risks for the average and RME conditions
fall between about 3 x 10"3 to 2 x 10"2. For the RME condition, TCE contributes about 92
percent of the total risk. Pathway-specific contribution to risk indicates inhalation while
showering accounts for 42 percent of the total, followed by ingestion of water (38
percent), and dermal contact with water (20 percent). The HI associated with this
scenario is 9 for the average condition and 20 for the RME condition. TCA (39 percent),
PCE (21 percent), and methylene chloride (20 percent) are the major contributors to non-
cancer risk. Ingestion (43 percent), dermal contact (43 percent), and inhalation (12
percent) account for 98 percent of the pathway-specific contribution to non-cancer risk.
For children, the estimated excess lifetime cancer risks for the average and RME
conditions fall between about 4 x 10"3 to 9 x 10"3. For the RME condition, TCE contributes
approximately 91 percent of the total risk. Pathway-specific contribution to risk includes
ingestion (50 percent), inhalation (30 percent), and dermal contact (20 percent) exposures
to groundwater. The HI associated with this scenario is 20 for the average case and 30 for
the RME estimate. TCA (34 percent), PCE (25 percent), and methylene chloride (18
percent) are the major contributors to the RME HI. Ingestion (51 percent) and dermal
contact (36 percent) account for 87 percent of the total pathway-specific contribution to
non-cancer risk.
SIORME70158.FORNAURODF1NALDOC 4-12
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Table 4-5
Identification of Key Chemicals and Exposure Pathways in the RA
Addendum That Drive the Carcinogenic Risk Assessment
Scenarios
Current Offsite Residential
- Adult. Average
- Adult. Reasonable
Maximum
- Child. Average
- Child. Reasonable
Maximum
Future Offsite Residential
- Adult. Average
Total Scenario
Risk
6 in 10.000.000 ,
8 in 10.000.000
1 in 1,000.000
3 in 1,000.000
3 in 1000
Chemicals That
Contribute
Chemical-Specific Risk £
1 in 1,000,000
(% Contribution to Total)
None
None
None
Heptachlor epoxlde (45%)
Dieldrin (29%)
alpha-BHC (6.9%)
Aldrin (6.4%)
Beryllium (5.6%)
Heptachlor (3.9%)
Bis (2-Ethylhexyl)phthalate (1.6%)
gamma-BHC (1%)
Trichloroethene (9 1 %)
Tetrachloroethene (6%)
Methylene chloride (3%)
Dieldrin (<1%)
Heptachlor epoxlde (< 1 %)
gamma-BHC (<1%)
Aldrin (<1%)
Exposure Pathways
That Contribute
Pathway-Specific Risk £
1 In 1.000,000
(% Contribution to Total)
None
None
Ingestlon of vegetables (57%)
Ingestion of fruits (32%)
Ingestlon of vegetables (55%)
Ingestion of fruits (29%)
Ingestion of drinking water (63%)
Dermal contact with water (23%)
Inhalation while showering (14%)
Ingestion of fruits (< 1%)
Ingestion of vegetables (< 1 %)
SLORME70158 FOFINAL\RODFINAL.DOC
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FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-5 (Continued)
Scenarios
Total Scenario
Risk
Chemicals That
Contribute
Chemical-Specific Risk £
1 in 1,000,000
(% Contribution to Total)
Exposure Pathways
That Contribute
Pathway-Specific Risk £
1 in 1,000,000
(% Contribution to Total)
Adult, Reasonable
Maximum
2 in 100
Trichloroethene (92%)
Methylene chloride (4%)
Tetrachloroethene (3%)
Dieldrin (<1%)
Heptachlor epoxide (< 1 %)
gamma-BHC (<1%)
Aldrin (<1%)
Bis(2-Ethylhexyl)phthalate (< 1%)
Heptachlor (<1%)
alpha-BHC (<1%)
Inhalation while showering (42%)
Ingestion of drinking water (38%)
Dermal contact with water (20%)
Ingestion of meat (< 1%)
Ingestion of dairy products (<1%)
Ingestion of fruits (< 1 %)
Ingestion of vegetables (< 1 %)
Child, Average
4 in 1,000
Trichloroethene (90%)
Tetrachloroethene (6%)
Methylene chloride (3%)
Dieldrin (<1%)
Heptachlor epoxide (< 1 %)
gamma-BHC (<1%)
Aldrin (<1%)
Bis(2-Ethylhexyl)phthalate (< 1%)
HIeptachlor (<1%)
Ingestion of drinking water (72%)
Dermal contact with water (19%)
Inhalation while showering (8%)
Ingestion of fruits (< 1 %)
[ngestion of vegetables (<]
Child, Reasonable
Maximum
9 in 1,000
Trichloroethene (91 %)
Tetrachloroethene (5%)
Methylene chloride (4%)
Dieldrin (<1%)
-leptachlor epoxide (< 1 %)
gamma BHC (<1%)
Aldrin (<1%)
Bis(2-Ethylhexyl)phthalate (< 1%)
Heptachlor (<1%)
alpha-BHC (<1%)
ngestion of drinking water (50%)
nhalation while showering (30%)
Dermal contact with water (20%)
[ngestion of vegetables (< 1 %)
ngestion of fruits (< 1%)
ngestion of meat (< 1 %)
SLDRME70158 FOfiNALNRODFINAl DOC
4 14
-------
Scenarios
Total Scenario
Risk
Chemicals That
Contribute
Chemical-Specific Risk £
1 in 1,000.000
(% Contribution to Total)
Exposure Pathways
That Contribute
Pathway-Specific Risk >
1 in 1,000,000
(% Contribution to Total)
Future Onsite Residential
- Adult, Average
- Adult, Reasonable
Maximum
- Child, Average
3 in 1,000
3 in 100
5 in 1000
Trichloroethene (79%)
Benzo(a)pyrene (11%)
Tetrachloroethene (5%)
Methylene chloride (3%)
Dibenzo(a,h)anthracene ( 1 %)
Beryllium (<1%)
Heptachlor epoxide (< 1 %)
betaBHC (<1%)
Dieldrin (<1%)
gamma-BIIC (<1%)
Aldrin (<1%)
Trichloroethene (83%)
Benzo(a)pyrene (9%)
Methylene chloride (4%)
Tetrachloroethene (3%)
Dtbenzo(a,h)anthracene (< 1 %)
Beryllium (<1%)
Dieldrin (<1%)
Aldrin (<1%)
alpha BHC (<1%)
betaBHC (<1%)
bis(2-ethy Ihexy Dphthalate (< 1 %)
gamma BHC (<1%)
rleptachlor (<1%)
Heptachlor epoxide (< 1 %)
Trichloroethene (80%)
Benzo(a)pyrene (9%)
Tetrachloroethene (6%)
Methylene chloride (3%)
3ibenzo(a,h)anthracene ( 1 %)
Ingestion of drinking water (57%)
Dermal contact with water (30%)
Inhalation while showering (12%)
Ingestion of soil (< 1%)
Dermal contact with soil (< 1%)
Inhalation of ambient air (< 1 %)
Ingestion of soil (< 1 %)
Ingestion of fruits (< 1%)
Ingestion of vegetables (< 1 %)
Inhalation while showering (37%)
Ingestion of drinking water (35%)
Dermal contact with water (27%)
Inhalation of ambient air (< 1 %)
Ingestion of soil (< 1 %)
Dermal contact with soil (<1%)
I nhala t ion of soil (< 1 %)
[ngestion of vegetables (< 1 %)
Ingestion of fruits (< 1%)
[ngestion of meat (< 1 %)
[ngestion of dairy products (<1%)
Ingestion of drinking water (66%)
Dermal contact with water (25%)
Inhalation while showering (7%)
Inhalation of ambient air (< 1%)
ngestion of soil (< 1 %)
SIC\RME70158FOWNAL\RODFINAL.DOC
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FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Scenarios
Child. Reasonable
Maximum
Total Scenario
Risk
1 in 100
Chemicals That
Contribute
Chemical-Specific Risk £
1 in 1,000,000
(% Contribution to Total)
Dieldrin (<1%)
Heptachlor epoxide (< 1 %)
Aldrin (<1%)
Beryllium (<1%)
betaBHC (<1%)
bis(2-ethylhexyl)phthalate (< 1 %)
gamma BHC (<1%)
Heptachlor (<1%)
Trichloroethene (82%)
Benzo(a)pyrene (5%)
Tetrachloroethene (4%)
Methylene chloride (3%)
Dibenzo(a,h)anthracene ( 1 %)
Dieldrin (<1%)
Aldrin (<1%)
alpha BHC (<1%)
Beryllium (<1%)
betaBHC (<1%)
bis(2-ethylhexyl)phthalate (< 1 %)
gamma BHC (<1%)
leptachlor (<1%)
Heptachlor epoxide (< 1 %)
Exposure Pathways
That Contribute
Pathway-Specific Risk >
1 in 1,000,000
(% Contribution to Total)
Dermal contact with soil (<1%)
Ingestion of fruits (< 1%)
Ingestion of vegetables (< 1 %)
Ingestion of drinking water (47%)
Inhalation while showering (27%)
Dermal contact with water (26%)
Inhalation of ambient air (< 1 %)
Ingestion of soil (< 1 %)
Dermal contact with soil (< 1%)
Ingestion of vegetables (< 1 %)
Ingestion of fruit (< 1 %)
ngestion of meat (< 1%)
Future Onsite Construction Worker
- Adult, Average
- Adult, Reasonable
Maximum
Sin 1.000.000
5 in 1,000,000
Beryllium (75%)
Beryllium (75%)
Ingestion of soil (54%)
Dermal contact with soil (29%)
I ngestion of soil (54%)
Dermal contact with soil (29%)
StC\RME70158 FO\FINAL\ROOF1NAL DOC
4-16
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Table 4-6
Identification of Key Chemicals and Exposure Pathways in the RA
Addendum That Drive the Noncarcinogenic Risk Assessment
Scenarios
Total
Scenario
Hazard Index
Chemicals That
Contribute
Chemical-Specific Hazard
Index3!
(% Contribution to Total)
Exposure Pathways
That Contribute
Pathway-Specific Hazard
Index3!
(% Contribution to Total)
Current Of fsite Residential (Subchronic)
- Adult, Average
Adult, Reasonable
Maximum
- Child, Average
Child, Reasonable
Maximum
0.06
0.1
0.2
0.5
None
None
None
None
None
None
None
None
Future Offsite Residential (Chronic)
- Adult, Average
- Adult, Reasonable
Maximum
- Child, Average
- Child, Reasonable
Maximum
9
r 20
20
30
1,1,1-Trichloroethene (33%)
Tetrachloroethene (28%)
Methylene chloride (17%)
l,U-Trichloroethane (39%)
Tetrachloroethene (21%)
Methylene chloride (20%)
Nickel (6%)
Tetrachloroethene (31%)
l,U-Trichloroethane (29%)
Methylene chloride (15%)
Nickel (8%)
Nitrate-Nitrite (7%)
1,1,1-Trichloroethane (34%)
Tetrachloroethene (25%)
Methylene chloride (18%)
Nickel (8%)
Ingestion of drinking water (56%)
Dermal contact with water (38%)
Ingestion of drinking water (43%)
Dermal contact with water (43%)
Inhalation while showering (12%)
Ingestion of drinking water (64%)
Dermal contact with water (31%)
Ingestion of drinking water (51%)
Dermal contact with water (36%)
Inhalation while showering (8%)
SLORME70158FOFINAL\nOOFINALDOC
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FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Scenarios
Total
Scenario
Hazard Index
Chemicals That
Contribute
Chemical-Specific Hazard
Index 3 1
(% Contribution to Total)
Nitrate-Nitrite (5%)
Toluene (3%)
Exposure Pathways
That Contribute
Pathway-Specific Hazard
Index * 1
(% Contribution to Total)
Ingestion of vegetables (3%)
Future Onsite Residential (Chronic)
- Adult, Average
- Adult, Reasonable
Maximum
- Child, Average
Child, Reasonable
Maximum
9
20
20
30
1,1,1-Trichloroethane (33%)
Tetrachloroethene (27%)
Methylene chloride (17%)
1,1,1-Trichloroethane (40%)
Tetrachloroethene (21%)
Methylene chloride (20%)
Nickel (6%)
Tetrachloroethene (31%)
1,1,1-Trichloroethane (29%)
Methylene chloride (16%)
Nickel (8%)
Nitrate-Nitrite (7%)
1,1,1-Trichloroethane (34%)
Tetrachloroethene (25%)
Methylene chloride (18%)
Nickel (8%)
Nitrate-Nitrite (5%)
Toluene (1%)
Ingestion of drinking water (56%)
Dermal contact with water (38%)
Ingestion of drinking water (43%)
Dermal contact with water (42%)
Inhalation while showering (12%)
Ingestion of drinking water (64%)
Dermal contact with water (31%)
Ingestion of drinking water (51%)
Dermal contact with water (36%)
Inhalation while showering (8%)
Ingestion of vegetables (3%)
Future Onsite Construction Worker (Subchronic)
- Adult, Average
Adult, Reasonable
Maximum
0.03
0.03
None
None
None
None
SLCARME70158.FOF INAURODFINAL DOC
4-18
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Table 4-7
. Summary of Carcinogenic Risks by Exposure Scenario
Scenario
Current Offsite
Residential
Future Offsite
Residential
Future Onsite Residential
Future Onsite
Construction Worker
Carcinogenic Risk
Birth to 7 years
Average
1 x NT6
4x10*
3xlOJ
NA
Reasonable
Maximum
3x10"
9 x 103
3 x 102
NA
Adult
Average
6xl07
3 x 103
5 x 103
5x10"
Reasonable
Maximum
8 x 107
2 x 10 '
IxlO2
5x10"
SlC\RME70t58FaflNAL\ROOf»NALDOC
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FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-8
Summary of Noncarcinogenic Risks for Chronic and Subchronic
Exposure Scenarios
Scenario
Future Off site Residential
Future Onsite Residential
Scenario
Current Offsite Residential
Future Onsite
Construction Worker
Chronic Hazard Index
Children
Average
20
20
Reasonable
Maximum
30
30
Adult
Average
10
10
Reasonable
Maximum
20
20
Subchronic Hazard Index
Children
Average
0.3
NA
Reasonable
Maximum
0.8
NA
Adult
Average
0.1
0.1
Reasonable
Maximum
0.2
0.1
SIC\RME70158 FOFINALVRODFINAL DOC
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917/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Similar magnitudes of potential risk are indicated for the future onsite residential exposure
scenario:
For adults, the estimated excess lifetime cancer risks for the average and RME
conditions fall between about 3 x 10'3 to 3 x 10"2. For the RME estimate, TCE
contributes about 83 percent of the total risk, followed by benzo(a)pyrene at
about 9 percent. Inhalation while showering (37 percent), ingestion of
groundwater (35 percent), and dermal contact with groundwater (27 percent)
account for 99 percent of the total pathway-specific risk contribution. The HI
associated with this scenario is approximately 9 for the average condition and
about 20 for the RME condition. TCA (40 percent), PCE (21 percent), and
methylene chloride (20 percent) are the major contributors to the HI. Ingestion
of groundwater (43 percent), dermal contact (42 percent), and inhalation (12
percent) while showering account for about 97 percent of the total pathway-
specific contribution to non-cancer risk.
For children, the estimated excess lifetime cancer risks for the average and RME
conditions fall between about 5 x 10"3 to 1 x 10'2. For the RME estimate, TCE
contributes approximately 82 percent of the total risk followed by
benzo(a)pyrene at 5 percent. The most significant contribution on a pathway-
specific basis is groundwater ingestion (47 percent) followed by inhalation of
compounds while showering (27 percent), and dermal contact with groundwater
(26 percent). The HI associated with this scenario is 20 for the average condition
and 30 for the RME condition. For the RME condition, TCA, PCE, and
methylene chloride are the major contributors at 34 percent, 25 percent, and
18 percent, respectively. Ingestion of groundwater (51 percent) and dermal
contact exposure with groundwater (36 percent) are the major pathway-specific
non-cancer risk contributors.
4.3 Environmental Evaluation
Qualitative evaluation of risk to ecological receptors indicates insignificant risks from
contamination present at OU2. Critical habitat for a threatened or endangered species, as
defined by the U.S. Fish and Wildlife Service, is not present at OU2. No threatened or
endangered species that are full-time residents of HAFB have been identified at OU2.
Two endangered species reside near the Base: bald eagles and peregrine falcons. Bald
eagles and peregrine falcons are not expected to receive significant exposure based on the
following:
Bald eagles feed primarily on fish. Fish resources in the vicinity of HAFB are
restricted to Weber River, and evidence suggests that fish in the river have not
been impacted by offsite migration of contaminants from OU2.
Other routes of exposure for both bald eagles and peregrine falcons (for example,
inhalation and direct ingestion of groundwater from springs and seeps are
insignificant. Ambient air concentrations are estimated to be very low and
drinking water sources are likely to be larger water bodies in the area.
Bald eagles are part-year residents and spend only the winter months in the
vicinity.
SLORME70158.FanNAL\ROORNALOOC 4-21
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917/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Potential impacts to alfalfa and cattle based on exposure to COPCs were evaluated. The
uptake of organic COPCs detected in groundwater was calculated for alfalfa and cattle.
Information on the toxic effects of the organic COPCs on alfalfa was not found in the
literature. In addition, no information was found on the maximum tolerable dietary levels
for cattle for the organic COPCs. Therefore, the toxicity of these compounds to alfalfa and
cattle could not be evaluated. Also, based on the concentrations detected, combined with
literature information on possible toxic effects, none of the inorganic COPCs are expected to
cause phytotoxicity in alfalfa or toxic effects in cattle.
Evidence does not suggest that fish and other ecological receptors inhabiting the Weber
River have been effected by offsite migration of groundwater from OU2. The TCE plume
terminates more than 4,000 feet southwest of the Weber River. However, should the
contaminant plume reach the Weber River sometime in the future, it is possible that fish
could bioconcentrate site-related chemicals. The estimated concentration of a chemical in
fish was estimated by the product of the concentration measured in groundwater and the
chemical-specific bioconcentration factor.
4.4 Uncertainty in the Risk Assessment
The risk assessment methodology is based on a variety of assumptions, conditions, and
factors. The purpose of the uncertainty analysis is to present key information that provides
a level of confidence that may be placed on the quantitative risk assessment. In general, the
risk assessment attempts to err on the side of safety by using conservative assumptions
regarding exposure and risk. Table 4-9 presents a qualitative discussion of each of the
above uncertainties and the potential impact on the BRA.
Major sources of uncertainty and their effects on the risk assessment include:
The prediction of human activities that lead to contact with media and exposure
to chemicals is highly uncertain. Assumptions used to estimate RME conditions
are conservative. The assumptions used in estimating risk include on-Base
residential land use, residential use of shallow groundwater, and individual risk
threshold criteria are the same as used for the population as a whole. Removal
of land use and use of shallow groundwater would make the risk negligible.
Removal of the risk threshold would reduce the significance of inhalation risk
estimates.
Some data from earlier investigations are uncertain due to the limited number of
chemicals analyzed and in some cases the analytical methods. The resulting
data base lacked analysis of groundwater samples for several chemicals detected
in soils at the site. In addition, nondetects or qualified values were used
quantitatively as appropriate. This adds uncertainty to the selection of COPCs
and could overestimate or underestimate exposure point concentrations.
Large numbers of assumptions are made to estimate release rates, model
environmental transport and fate, and quantify exposure. Food chain modeling
introduces considerable uncertainty to exposure point concentration estimation.
This adds uncertainty which could result in overestimation of risk.
SLORME70158.FOFINAL\ROORNALOOC 4-22
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FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 4-9
Summary of Uncertainties
Condition/
Assumption
Source of
Uncertainty
Quantitative
Effect
Impact of Risk
Characterization
Physical Setting
Onsite residential land
use
Residential use of
shallow groundwater
Individual risk threshold
criteria same as
population
Use of default
assumption
Use of default
assumption
Use of default
assumption
Overestimates risk
Overestimates risk
Overestimates risk
Very high; removal of
condition would make
risk from onsite surface
soils negligible.
Very high; removal of
condition would make
shallow groundwater
negligible contributor to
risk for most scenarios
Medium; would reduce
significance of offsite
inhalation risk estimates
Contaminant of Potential Concern
Pesticide presence
Polyaromatic
Hydrocarbons (PAH)
presence
Background
concentrations
characterization
Use of filtered
groundwater sample
results vs. unfiltered
sample results
Assumed to be due to
waste disposal
Single groundwater
sample
Data adequacy
Professional judgment
Overestimates risks;
condition is probably
due to area-wide
agricultural activities
Overestimates risks;
PAHs not widely found
Unknown
Filtered samples more
repeatable. Turbidity
may effect total
concentration
Medium; major risk
contributors for certain
exposure scenarios
Low; PAHs not a major
risk
Low; data considered
reasonably complete and
representative
Low to medium; some
filtered samples show
lower values
Exposure Assessment
Pathways combine
maximally in single
individual
100% bioavailability for
absorption upon contact
with media
Use of default
assumption
Use of default
assumption
Possible overestimation
of risk
Overestimation of risk
Toxicity Assessment
Toxicity factors missing
forSi,Co,delta-BHC,
etc.
Use of unverified values
for trichloroethene
Possible synergistic or
antagonistic effects of
multichemical exposure
Factors lacking
Verified factors lacking
Data inadequacy
Low underestimation .
Moderate
overestimation
Unknown
Possibly large; unlikely
that significant population
will be maximally
exposed by all pathways
Moderate;
inhaiation/ingestion
adsorption of contaminant
varies
Unknown; could result in
an underestimation of
overall site risks
Unknown; trichloroethene
RfD under review
Unknown; could lead to
an over- or
underestimation of risks
SLDRME70tS8.FORNAL\ROORNALOOC
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917/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
The prediction of risks associated with the dermal exposure pathway is difficult
because mechanisms to quantify the contribution of dermal absorption are not
well established and considerable uncertainty surrounds estimates of dermal
exposure and risk.
Uncertainties associated with the toxicity assessment include use of alternate
RfDs, use of oral RfDs as dermal RfDs, and lack of toxicity data. Risk and doses
within an exposure route are assumed to be additive when, in fact synergisms
and antagonisms occur. This could act to overestimate or underestimate risk.
4.5 Overview of Site Risks
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and
substantial endangerment to public health, welfare, or the environment.
Remedial action at OU2 is warranted based on potential future risks to human health and
the environment, i.e., to prevent a significant risk to residents. Also, remedial action is
generally warranted when MCLs are exceeded. VOCs associated with domestic
groundwater use account for the majority of the risk by ingestion and inhalation pathways.
SLORME70l58FOflNAL^OOFlNALDOC 4-24
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917/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
5. DESCRIPTION OF ALTERNATIVES
As part of the FS for OU2 (Radian, 1993, and CH2M HILL, 1994), media-specific remedial
alternatives were developed for groundwater, springs and seeps, and soil. OU2 is
addressed as source area and non-source area components (Figure 5-1), because it is
technically more feasible to address different parts of the OU to best meet the media-
specific remedial action objectives for protectiveness of human health and the environment.
In the development of the source area alternatives, the following media were considered to
address chemicals of concern: groundwater, unsaturated soil (vadose zone), and saturated
soil. No surface water exists within the source area. In the non-source area, the following
media were considered to address chemicals of concern: groundwater and water flowing
from springs and seeps. The FS distinguished between unsaturated soil (vadose zone) and
saturated soil (saturated zone) to better identify the use and feasibility of media-specific
technologies.
Alternatives developed for both source and non-source areas incorporate and build upon
prior response actions. These actions were implemented to address potential exposures or
to achieve significant risk reductions quickly. The source area alternatives include the
interim remedial action consisting of extraction and treatment of free-phase DNAPL in the
source area by the Source Recovery System (SRS). DNAPL is further addressed in the
source area alternatives. The non-source area alternatives include two prior removal
actions: collection and treatment of water flowing from contaminated springs and seeps in
the non-source area; and providing a permanent alternate water supply for residences in
the OU2 non-source area.
5.1 Development Of Alternatives
Remedial alternatives are developed by assembling technologies into combinations
appropriate to each medium. Steps used to develop remedial alternatives for OU2 include
development of general response actions and remedial action objectives for each medium,
followed by a preliminary screening and evaluation of technologies and process options.
General response actions for each medium identify basic actions that might be undertaken
as part of a remedial action and include: prevention of human exposure to contaminated
media, protection of uncontaminated groundwater for current and future use, restoration of
contaminated media for future use, and prevention of cross-contamination of media.
Several technologies may exist for each general response action. The preliminary screening
of technologies for each general response action involves evaluation of technical
implementability. In the process option evaluation, technically implementable technologies
are evaluated with respect to effectiveness, implementability, and cost.
SLDRME701S8.FORNAL\ROORNALOOC 5-1
-------
LIMITS Of
GROUNDWATER
APPROX. LIMITS
OF SOURCE AREA
FORMER CHEMICAL
DISPOSAL TRENCHES
NON-SOURCE AREA INCLUDES
AREA OF GROUNDWATER
CONTAMINATION EAST OF
HILL AIR FORCE BASE BOUNDARY
Figure 5-1
DELINEATION OF SOURCE
AREA AND NON-SOURCE
AREA AT OU2
OcMTMtt unit 2. MM AT Force Base. Ufa"
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917/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Remedial action objectives (RAOs) are medium-specific goals for protecting human health
and the environment. These include preliminary cleanup goals, areas of attainment and
estimated restoration time frames. The RAOs for OU2 include:
Meet chemical-specific ARARs such as drinking water Maximum Contaminant
Levels (MCLs) under the Safe Drinking Water Act. Meeting MCLs will also meet
Utah Groundwater Quality Standards for the chemicals of concern.
Limit cancer risk to less than 10-* with a target of 10*6 due to incidental ingestion,
dermal contact, or inhalation of vapors.
Reduce contaminant concentrations low enough to avoid chronic health effects
(as indicated by a hazard index of less than one).
Remove as much of the DNAPL as practicable.
Eliminate the sources of groundwater contamination either through source
control or removal in accordance with the Utah Corrective Action Cleanup
Standards Policy - UST and CERCLA Sites.
Prevent further degradation of groundwater quality in accordance with the Utah
Corrective Action Cleanup Standards Policy - UST and CERCLA Sites.
The COCs consist of chlorinated solvents in the form of DNAPL, VOCs in the dissolved
phase, and pesticides (source area). Inorganic compounds do not contribute significantly to
cumulative risks. The major components of the DNAPL are: TCE (approximately 75
percent), TCA (18 percent), PCE (6 percent), toluene (1 percent), and smaller amounts of
methylene chloride and Freon TF. The area of attainment for soils includes the original
disposal pits, the known extent of DNAPL, and where groundwater concentrations are
highest and may indicate the presence of residual DNAPL. For chemicals of concern
(COCs) dissolved in groundwater, the area of attainment is defined by maximum
contaminant levels (MCLs). TCE is used as the indicator chemical because it is the most
frequently found and most widespread. All other chemicals dissolved in groundwater
which exceed RAOs are located within the TCE area of contamination. Where chemical-
specific ARARs are not available, risk-based concentrations corresponding to the 10*
residential exposure scenario have been established as preliminary remedial goals (PRGs).
Risk-based PRGs were established for VOCs found in soils in the source area and Beta BHC
in the source area groundwater.
Twelve alternatives addressing source area contaminants and seven alternatives addressing
non-source area contaminants were developed. The alternatives assembled for each
medium begin with the No Further Action Alternative, which is required by the NCP to be
included in the comparison process. The alternatives for each medium were initially
screened for effectiveness, implementability, and cost. Alternatives which did not meet the
criteria of protectiveness, compliance with ARARs, or performed poorly under the
screening criteria were eliminated from further consideration. Tables 5-1 and 5-2
summarize the source area alternatives. Table 5-3 summarizes alternatives for the non-
source area.
SLORME70158.FOf1NAL\ROOflNALOOC 5-3
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917/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 5-1
Source Area Alternatives for Groundwater
4$a^ ^y^^^^^ >
rocess Options
8|9 10M1 12
Groundwater
Access Restrictions
Deed/Water Rights
Restrictions
Source
Monitoring
Groundwater
Source
Capping
lay
Source
Vertical Barrier
Slurry Wall
Downgradient
Source Perimeter
Extraction
Extraction Wells
Source
Physical/Chemical treatment
Gravity Separation
Extracted Water
Steam Stripping
queous Phase
Air Stripping
queous Phase
ffsite Treatment
Liquid injection incinerator
rganic Phase
nsite treatment
WTP
queous phase
ffsite discharge
OTW
queous phase
n-situ thermal treatment
Steam stripping
ource
V Indicates that the remedial technology Is an element of the alternative.
SLORME70158 FOFINALNRODFINAL DOC
5-4
-------
Table 5-2
: Source Area Alternatives for Soil
MedlUHi
'$?#' .'$*
Soil
Remedial TecHHojB§y;g
Access Restrictions
Monitoring
Capping
Vertical Barrier
Shallow excavation
Deep excavation
Ex-situ dewatering
Ex-situ chemical treatment
Offsite Disposal
In-situ physical treatment
In-situ dewatering
* '« l?fe?Fll **» ^'.* »> i
^^'F#Proce&
? £*£lt** *^iM$vfE
f Options <**;??**
Deed Restrictions and
Fencing
Borings
Clay
Slurry Wall
Backhoe
Clam Shell
Pressure Filtration
Fixation/Solidification
Hazardous waste landfill
Vacuum extraction/soil
venting
Soil flushing
Steam stripping
Extraction wells
m^^m^
'-: or volume
Source
Source
Vadose Zone
Saturated Zone
Staturated Zone
Vadose Zone
Saturated Zone
Vadose Zone
Saturated Zone
Vadose Zone
Saturated Zone
Saturated Zone
Alternative
ijp
V
<:.-
V
V
5,1
V
V
7;i
V
V
8
V
V
.9V
V
V
10
V
V
11
y
V
12
V
V
See "Capping" in Table 5-1
See "Vertical Barrier" in Table 5-1
V
V
V
V
V
V
V
V
V
J
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
See "Extraction" in Table 5-1
V Indicates that the remedial technology Is an element of the alternative.
SLC\RME70I58.FOFINAL\ROOFINAL DOC
55
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917/96
FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
Table 5-3 |
Non-Source Area Alternatives
.-";-- £!?;>. :
Medium
" . , ^*V
Groundwater
Surface Water
SoH
. . ;".'... /xir'j^»»T
i Remedial Technology
*' " . <*::,' :---.- ' -4
"?- ',''"'.«, . -t
Access Restrictions
Alternate Water Supply
Monitoring
Vertical Barrier
Extraction
Subsurface Drain
Physical/Chemical Treatment
Onsite treatment
Offsite discharge
In-situ Treatment
Access Restrictions
Alternate Water Supply
Monitoring
Interceptors
Physical/Chemical Treatment
Onsite Treatment
Offsite discharge
Onsite Discharge
Access Restrictions
Monitoring
In-situ Physical Treatment
£.Ji%^vvv:,..;;.; J,::, ;;;B;-
. Representative . ;
. , Process Options '
Deed/Water Rights Restrictions
Domestic
Qroundwater
Hydraulic Barrier
Extraction Wells
nterceptor Trench
Air Stripping
IWTP
POTW
Air Stripping
Deed/Water Rights Restrictions
Agricultural
Surface Water
French Drain
Carbon Absorption
IWTP
POTW
Stream
Deed Restrictions
Soil Gas
Vacuum extraction/soil venting
Air Stripping
. .-. . "': . t
?" f^S«^- ."'-:.:
V '" Awe .
f; or Volume
lume > MCL
Residential
lume > MCL
Plume > MCL
Plume > MCL
Plume > MCL
Extracted Water
Extracted Water
Extracted Water
Plume > MCL
Plume > MCL
Current Users
Existing Seeps
Plume > MCL
Collected Water
Collected Water
Collected Water
Collected Water
Equipment
Residences
Vadose Zone
Saturated Zone
Alternative
" -^^mm^ I
jir "-:3-3K&&*'3,r-
'-' '"i;;-^^^^'----
V
V
V
V
^
^
V
^
V
V
V
^
V
V
V
^
V
V
V
V
V
V
V
T/
^
^
V
^
>/
^
^
V
V
V
^
V
^
V
V
^ I
^
>/
vl
>J
* I
V
^ tl
V H
Jl
>/ I
V
V I
V
V
v I!
V
V
V .
V I
V Indicates that the remedial technology is an element of the alternative.
SLaRME70l58.FO\FINAL\RODFlNALDOC
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
5.2 Detailed Analysis of Alternatives
To reduce the number of alternatives for detailed analysis, the original assembled
alternatives were further screened against the criteria of: long-term effectiveness and
permanence; reduction in toxicity, mobility, and volume through treatment; short-term
effectiveness; implementability; and cost. Five source area alternatives and four non-source
area alternatives were the most promising and were carried forward for the detailed
analysis.
There are three common elements to all of the alternatives carried forward into the detailed
analysis of alternatives which are discussed here for conciseness. These include:
Monitoring for contaminants in groundwater and treatment system
performance. Groundwater monitoring will assess contaminant concentrations,
location, and transport and will comply with RCRA requirements specified in 40
CFR, Part 264, Subpart F and Utah Administrative Code (UAC) R315-8-6.
Because these alternatives will result in hazardous substances onsite above
health-based levels, a review will be conducted within five years after
commencement of the remedial action to ensure that the remedy continues to
provide adequate protection of human health and the environment.
Institutional controls to prevent completion of potential exposure pathways or to
protect facilities installed as part of the remedy.
Institutional Controls for properties not fee-owned by the Air Force will include: water
rights and well drilling restrictions and advisories to prevent exposure to contaminated
groundwater; and fencing with warning signs to restrict access to exposure areas,
construction areas, and treatment facilities. Leases or easements may be needed to enact
some of the institutional controls.
The Utah Department of Natural Resources, Division of Water Rights has developed a
groundwater management plan for the Weber Delta sub-area of the East Shore area, which
includes HAFB. Areas of groundwater contamination surrounding HAFB are identified as
restricted. No new wells will be permitted in the restricted areas nor will change
applications which propose to transfer water into these areas be granted. When the
contamination is successfully cleaned up and no longer poses a threat to groundwater
aquifers, the State Engineer will consider allowing the construction of wells in these areas.
Institutional controls for Air Force fee-owned property will include: (1) issuing a continuing
order (which remains in effect as long as the property is owned by the Air Force) which
restricts access to or disturbance of contaminated soil or groundwater, such as construction
activities or installation of water supply wells in zones of contaminated groundwater,
(2) filing a notice to the deed detailing the restrictions of the continuing order, and (3) a
covenant to the deed in the event of property transfer.
In the case of sale or transfer of property within OU2 by the United States to any other
person or entity, the Air Force will place covenants in the deed restricting access and
prohibiting disturbance of contaminated soils or the remedial action without approval of
the United States. These covenants will be in effect until removed upon agreement of the
SLDRME70158.FORNAL\ROOFINALDOC 5-7
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9/17/96 FINAL RECORD OF DECISION FOR OPERABLE UNIT 2
State of Utah, the U.S. Environmental Protection Agency, and the U.S. Air Force or their
successors in interest. The Air Force will also include in the deed the covenants required by
section 120(h)(3) of the Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA), which include a warranty that the United States will conduct any
remedial action found to be necessary after the date of the transfer; and a right of access in
behalf of the U.S. Environmental Protection Agency and the Air Force or their successors in
interest to the property to participate in any response or corrective action that might be
required after the date of transfer. The right of access referenced in the preceding sentence
shall include the State of Utah for purposes of conducting or participating in any response
or corrective action that might be required after the date of transfer.
In the event that the land use is changed or structures are removed, the Air Force will
reevaluate the protectiveness of the remedy selected for OU 2, and will take any
appropriate remedial action.
5.2.1 Source Area Alternatives
As a result of screening, Source Area Alternatives 1,4,5,11, and 12 were carried forward in
the FS for detailed evaluation.
In addition to the common elements for all alternatives, all of the source area alternatives
include common elements. These are:
Continued operation of the SRS. The SRS was installed to recover as much
DNAPL as practicable and treat VOC-contaminated groundwater for discharge
to the IWTP. Depending on the alternative, treatment systems within the SRS
will be upgraded to handle the additional load and treatment needs. The IWTP
currently operates in compliance with a pre-treatment permit from the North
Davis County Sewer District (NDCSD).
Uncertainty in the amount of DNAPL which can be effectively removed from the
subsurface by conventional technologies, such as the pump and treat system at
the SRS. The application of innovative technologies to residual DNAPL is
expected to enhance this recovery, but it is uncertain to what degree. While a
waiver to groundwater remediation standards in the source area is not included
in this ROD, it will be considered in the future if application of planned
innovative technologies demonstrate the standards cannot be achieved.
5.2.1.1 Source Area Alternative 1
Alternative I, the No Further Action Alternative for the source area, involves continued
operation of the SRS and implementation of the groundwater monitoring program. The
SRS will continue operation as long as DNAPL can be practicably recovered. The SRS uses
wells to pump DNAPL and the associated contaminated groundwater to the treatment
system; gravity separation of the organic and water phases; offsite liquid injection
incineration of the organic phase; onsite steam stripping of the aqueous phase; and transfer
to the IWTP for further treatment and discharge to the POTW. When no more DNAPL can
be practicably recovered, operation of the SRS would discontinue. No other containment
collection, treatment, discharge process options, or active treatment are included in this
alternative.
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The No Further Action Alternative in the source area relies on natural attenuation by
physical chemical and biological processes to reduce contaminant concentrations. Under
the No Further Action Alternative, the time frame for natural attenuation of contaminants
to acceptable remediation levels has been estimated to be greater than 25,000 years.
Before the contaminants would naturally attenuate, the future carcinogenic risk under this
alternative for off-Base residents would increase to levels comparable to hypothetical future
on-Base residents and would range from a low of 1.6 x 10* to a high of 9.9 x 10*2. This risk
scenario and restoration time frame is not reasonable given the circumstances of the site,
and thus would not comply with chemical-specific ARARs. The time to implement this
alternative is estimated to be less than 3 months.
The total capital cost of this alternative is estimated at $28,000. The estimated operation and
maintenance cost is $27,000 per year. The total 30-year present worth cost of this alternative
is estimated at $450,000.
5.2.1.2 Source Area Alternative 4
This alternative consists of the elements described in Source Area Alternative 1, with the
addition of the following: continued operation of the SRS with additional groundwater
extraction wells to address dissolved phase contaminants; onsite treatment of the aqueous
phase before discharge; and in situ treatment of the source area soils.
Installation of additional groundwater extraction wells would require about 2 months. An
estimated 90 gallons per minute of extracted groundwater would be treated by the SRS,
pumped to the Base IWTP, and eventually discharged to a POTW. The SRS would be
modified to add air-stripping or other treatment processes as needed to comply with pre-
treatment requirements.
In situ Soil Vapor Extraction (SVE) or technology with similar or improved performance
expectations would be applied to the vadose zone source area volume of "soils. SVE is an in-
situ presumptive remedy for VOC-contaminated soils, dean air is injected or passively
flows into the unsaturated contaminated subsurface soils. VOCs are then removed as
vapors by extraction wells. The vapors would be collected and treated at the surface using
activated carbon filtering, catalytic oxidation, or other technologies. Construction of the
SVE system is expected to take approximately 2 months. It is anticipated that the SVE
system will be in operation for a minimum of 5 years.
Several planned innovative technologies offer enhanced recovery of DNAPL. One is an
innovative application of SVE in which the saturated deep soils in the vicinity of former
Chemical Disposal Pit 3 would be dewatered using the network of groundwater extraction
wells and applying SVE to this zone. Other technologies include steam injection and the
use of surfactants. Steam injected into the contaminated soils will physically move DNAPL
and vaporize contaminants. Injecting a surfactant solution into the contaminated soils
would increase the mobility and/or solubility of hydrophobic liquids such as DNAPL. The
extracted fluids will be treated at the SRS with further treatment at the IWTP prior to
discharge. Treatability studies will be conducted prior to full-scale use to verify any
innovative technology will fulfill its performance expectations at OU2.
Additional ARARs with which Source Area Alternative 4 would comply pertain to air
emissions and the injection of fluids into the subsurface. Best Available Control
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Technologies (BACT) would be used to control air emissions. The SVE system would be
designed to satisfy treatment ARARs associated with RCRA as well as standards for the
control of air emissions (40 CFR Part 60; UAC R307-1-3). If soil surfactant flushing is used,
it would be conducted in conformance with the State Underground Injection Control
Regulations. Once the remedy is complete, it is expected that ARARs will be met.
Source Area Alternative 4 will remediate to chemical-specific remediation goals for
chlorinated VOCs. The remediation time frame may substantially exceed 30 years. The
residual carcinogenic risk for on-Base residents following remediation would range from a
low of 3.7 x 10* to a high of 1.12 x Iff4. Features of this alternative would require 6 to 12
months to construct. In situ treatment processes would be implemented in phases. The
first phase would involve completion of the SRS DNAPL removal. The next stage would be
dewatering of the source area and implementation of SVE treatment.
Steam injection is used as the representative process option for cost estimates, i.e., cobts for
Source Area Alternatives 5,11, and 12 also include use of steam injection. The total capital
cost of this alternative is $2,738,000. The annual operation and maintenance cost is
estimated to be 52,329,000. The 30-year present worth cost is estimated at $19,137,000.
5.2.1.3 Source Area Alternative 5
This alternative is the same as Source Area Alternative 4, with the addition of a vertical
barrier constructed along the downgradient edge of the DNAPL. The entire length of the
500-foot-long vertical barrier will be keyed into the low permeability clays and silty clays of
the Alpine Formation with an average depth of approximately 70 feet. Instead of relying on
the steep drawdown to direct water away from the eastern side of the source area, a vertical
barrier will be constructed for added hydraulic control of groundwater. This would hinder
contamination from migrating into the non-source area, but would not prevent the influx of
uncontaminated groundwater or rain water into the source area.
The ARARs for Source Area Alternative 5 are the same as for Source Area Alternative 4,
with the additional requirement of compliance with the Land Disposal Restrictions (LDRs)
[40 CFR Part 268; UAC R315-13]. Soil excavated from construction of the barrier may
contain VOCs. The Source Area and area immediately adjacent needed for construction
will be 'defined as a Corrective Action Management Unit (CAMU). Soils from construction
will be kept within the CAMU and will not trigger the LDRs. The excess soils will be
replaced onsite to serve as the grading layer to establish proper slopes for the surface cap.
The LDRs would otherwise be applicable to excavated soils which contain TCE or other
spent solvents.
Source Area Alternative 5 will remediate to chemical-specific remediation goals for
chlorinated VOCs. The remediation time frame may exceed 30 years. The residual
carcinogenic risk for on-Base residents after remediation would range from a low of 3.7 x
10 "* to a high of 1.12 x 10^. The estimated time to construct all elements of this alternative is
12 to 15 months, including about 3 months for construction of the barrier.
The total capital cost of this alternative is $4,994,000. The annual operating and
maintenance cost is estimated to be $2376,000. The 30-year present worth cost of this
alternative is estimated at $22,118,000.
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5.2.1.4 Source Area Alternative 11
Source Area Alternative 11 is the same as Source Area Alternative 4, except an encircling
barrier will be installed around the DNAPL zone and a surface cap will be constructed. The
purpose of the encircling vertical barrier will be to prevent the down gradient migration of
groundwater contaminants and the inflow of uncontaminated groundwater from the
upgradient direction. The encircling vertical barrier and surface cap will provide
containment of the DNAPL area and will be keyed into the Alpine Formation which lies at
depths up to 70 feet below the ground surface. The type of vertical barrier will be
determined during design. Options such as deep soil mixing and sheet piles will be
considered in addition to a slurry wall. The estimated length of the barrier is 1,300 linear
feet, encircling an area of about 1.4 acres. The surface cap will be designed to prevent
erosion and decrease the inflow of surface water through contaminated soils to reduce
transport of contaminants to groundwater. Construction of the surface cap over the former
chemical waste disposal pits will be delayed until after source control and treatment
systems are constructed and their effectiveness evaluated. This is to minimize disturbance
to the cap from in situ treatment.
ARARs for Source Area Alternative 11 are the same as for Source Area Alternative 5, with
the addition of landfill closure requirements under RCRA Subpart G [40 CFR Part 264; UAC
R315-8-14]. Because no waste was placed in former Chemical Disposal Pit 3 after 1980, the
RCRA closure requirements are relevant and appropriate for wastes left in place and
applicable for the wastes generated by excavation.
Source Area Alternative 11 will remediate to chemical-specific remediation goals for
chlorinated VOCs. The residual carcinogenic risk for on-Base residents after remediation
would range from a low of 7.2 x 10"* to a high of 2.4 x 10*. The encircling barrier will allow
the isolation of the DNAPL zone providing the opportunity to reduce the restoration time
from more than 30 years to a 15 to 30-year period. Containment of the DNAPL and highly
contaminated groundwater will be achieved once the vertical barrier wall is constructed.
This alternative will require 12 to 18 months to construct all of the elements, including
about 4 months for the cap.
The capital cost of this alternative is estimated to be $6,897,000. The annual operation
maintenance costs is estimated to be $2,012,000. The 30-year present worth cost of this
alternative is estimated at $20,910,000.
5.2.1.5 Source Area Alternative 12
This alternative is similar to Source Area Alternative 11 in that an encircling vertical barrier
around the DNAPL and a surface cap will be constructed. There are two added elements:
excavation of shallow soils and soil flushing to treat deeper soils beneath the water table.
In the immediate area of the fonner trenches, the shallow soils will be excavated. Standard
backhoe excavation methods will be used to remove the upper 25 feet of overburden in the
immediate vicinity of the fonner Chemical Disposal Pit 3. Approximately 6,400 cubic yards
of contaminated soil will be removed, treated as necessary, and disposed either onsite or
offsite in compliance with the land disposal restrictions.
This excavation would remove shallow soils contaminated with VOCs. Clean material will
be backfilled into the excavation. Shallow soils that are not excavated and treated will be
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treated using a network of SVE wells. The construction of the cap over the former disposal
trenches will be delayed until after the source control treatment system is constructed. Soil
flushing injects a surfactant solution into the contaminated soils to increase the mobility or
solubility of hydrophobic chemicals such as those comprising the DNAPL. The surfactant
solution, mobilized DNAPL, and dissolved VOCs will be recovered by extraction wells and
routed to the SRS as in the other alternatives.
ARARs for Source Area Alternative 12 are the same as for Source Area Alternative 11. Once
the remedy is complete it is expected that ARARs will be met.
Source Area Alternative 12 will remediate to chemical-specific remediation goals for
chlorinated VOCs in soil. The residual carcinogenic risk for on-Base residents after
remediation would range from a low of 7.2 x 10"* to a high of 2.4 x 10*. It is estimated that
the time to excavate the shallow soils is approximately 6 months. Containment of the
DNAPL and highly contaminated groundwater will be achieved with construction of the
vertical barrier. This alternative will require 18 to 24 months to construct all elements.
The estimated capital cost of this alternatives is $14,234,000. The annual operation and
maintenance cost is estimated to be $740,000. The estimated 30-year present worth cost of
this alternative is $24,070,000.
5.2.2. Non-Source Area Alternatives
Non-source area alternatives address contamination transported from the source area and
focus on remediating the off-Base shallow contaminated groundwater and the
contaminated springs and seeps. Of the seven non-source alternatives evaluated,
Alternatives 1,3,5, and 7 were carried forward for detailed evaluation in the FS. In
addition to the common elements for all alternatives/ all of the non-source area alternatives
include common elements. These are:
Continued operation of systems to treat seeps and springs. The water is
collected, treated onsite, and discharged. However, the flow rate of the seeps
and springs have varied historically with seasonal and climatic changes. Also,
implementing a pump and treat system may cause some of the seeps or springs
to dry up. Operation of the seep and spring treatment system is required while
there is sufficient flow for effective treatment. Discharge limits are subject to
UPDES requirements for direct discharge to surface waters, subject to the pre-
treatment requirements for the receiving POTW, or subject to limits set by the
IWTP when discharging through the SRS.
Alternate water supplies have been provided to effected property owners for
agricultural use.
All of the non-source area alternatives, with the exception of Non-Source Area Alternative
1, would meet ARARs, including the chemical-specific groundwater standards as
restoration goals. The residual carcinogenic risk after remediation for all non-source area
alternatives, except Non-Source Area Alternative 1, would be in the lower part of the 10* to
10"6 cumulative risk range. In undeveloped areas, neither volatilization of organic
compounds nor wind entrainment of contaminated dust are expected to pose a significant
exposure pathway.
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5.2.11 Non-Source Area Alternative 1
Alternative I, the No Further Action Alternative for the non-source area, involves
continued implementation of the alternate water supplies and systems to intercept and treat
contaminated seep and spring discharge. No additional containment, collection, treatment
or discharge process options are included in this alternative. This alternative relies on
natural physical, chemical, and biological processes to lower contaminant concentrations
until cleanup levels are met. Concentrations in the source area are high, including separate
phase liquids. These processes act slowly. The estimated remediation time will be
hundreds to thousands of years before groundwater remediation standards would be met.
This is an unacceptable time frame given the circumstances of the site, and would not
comply with chemical-specific ARARs. This alternative includes periodic monitoring of
groundwater as well as spring/seep locations.
MCLs are relevant and appropriate as ARARs for restoration of groundwater and
seeps/springs. MCLs are identical performance standards to those under the Utah
Groundwater Protection Rule, except for lead and copper which are not COCs for OU2. If
onsite treatment satisfies all surface water discharge requirements, the treated water may be
discharged to an onsite stream in compliance with water quality discharge standards of the
Clean Water Act (40 CFR Part 122; UAC R317-8) instead of pumping the water to the IWTP
prior to discharge to a POTW. Treated water discharged to the POTW will meet the
requirements of the POTW to comply with pre-treatment permit conditions.
All current and future risks will remain under this alternative. The time to construct the
additional groundwater monitoring wells is less than 6 months.
Non-Source Area Alternative 1 has an estimated capital cost of $130,000. The estimated
annual operation and maintenance cost is $172,000. The estimated 30-year present worth
cost of this alternative is $2,778,000. The duration of monitoring would exceed 30 years.
5.2.2.2 Non-Source Area Alternative 3
This alternative will include the elements of Non-Source Area Alternative 1* with the
addition of the following innovative technology: in situ air sparging of groundwater with
SVE in vadose zone soils to collect contaminated soil gas from air sparging. Air sparging
operates by injecting air through wells which are below the water table. The air bubbles
move upward through the groundwater into the vadose (unsaturated) zone. As the air
passes through the contaminated groundwater, contaminants volatilize from the water and
enter the air. The air is then collected by the SVE system, treated if required, and vented to
the atmosphere.
Additional ARARs which will be met include compliance with air quality regulations [e.g.,
40 CFR Part 60; UAC R307-1-3J.
An estimated 3,050 pounds of contaminants would be removed from the subsurface.
Construction of the system would take approximately 2 months. Estimates for restoration
time frame is 15 years in the FS. Due to uncertainties in the hydrogeology, a longer time
frame was considered likely, so present worth costs were estimated for 30 years. The time
to construct the features of this alternative is 12 to 24 months.
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The capital cost of this alternative is estimated to be $9300,000. The annual operation and
maintenance cost is estimated to be $1,160,000. The estimated 30-year total present worth
cost of this alternative is $17,900,000.
5.12.3 Non-Source Area Alternative 5
This alternative is similar to Non-Source Area Alternative 3, except shallow groundwater
will be extracted and treated, rather than being treated in situ. This extraction system will
utilize one or more shallow groundwater extraction trenches and/or extraction wells to
capture the groundwater. The initial phase will intercept the outer portion of the plume
and additional monitoring will be used to estimate a remedial time frame. Onsite air
stripping of the groundwater will be employed, if needed, to meet pretreatment
requirements for discharge.
ARARs which will be met are the same as for Non-Source Area Alternative 3, except the air
quality requirements would pertain to the air stripper.
An estimated 3,100 pounds of contaminants would be extracted from contaminated shallow
groundwater. Complex hydrogeology makes accurate modeling difficult; time frames
range from 15 to 70 years. Additional extraction systems will be installed in the plume if
the monitoring results indicate an excessive remediation time frame, such as more than 30
years.
This alternative will require 12 to 18 months to construct. The installation of the
groundwater collection system would be phased.
The capital cost is estimated to be $5,100,000. The annual operation and maintenance cost is
estimated at $610,000. The estimated 30-year total present worth cost is estimated at
$11,000,000.
5.2.2.4 Non-Source Area Alternative 7
This alternative combines the elements of Non-Source Area Alternatives 3 and 5. In situ air
sparging with SVE will treat the interior of the shallow groundwater plume. A shallow
groundwater extraction and treatment system (air stripping) will be used along the
northern edge of the TCE plume.
ARARs are the same as for Non-Source Area Alternatives 3 and 5 and will be met.
An estimated 3,100 pounds of contaminants would be extracted from contaminated shallow
groundwater. This alternative will require 12 to 24 months to construct. The installation of
the groundwater collection system would be phased. Initially, the perimeter interception
system would be installed along the north edge of the TCE plume to intercept the full width
of the plume. Additional extraction systems will be installed in the plume if the monitoring
results indicate an excessive remediation time frame, such as more than 30 years.
The capital cost is estimated at $8,700,000. The annual operation and maintenance costs is
estimated at $950,000. The 30-year total present worth cost is estimated to be $17,000,000.
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6. SUMMARY OF COMPARATIVE ANALYSIS
OF ALTERNATIVES
The comparative analysis evaluates the relative performance of the alternatives within the
nine evaluation criteria established in the National Oil and Hazardous Substances
Contingency Plan (NCP) listed below. The first two evaluation criteria are threshold
criteria which must be met by the selected remedial action. The five balancing criteria are
balanced to achieve the best overall solution. The final two modifying criteria that are
considered in the remedy selection are state acceptance and community acceptance.
Threshold Criteria
Threshold criteria include overall protection of human health and the environment and
compliance with ARARs. These threshold criteria must be met by an alternative before it
can be evaluated under the five balancing criteria.
1. Overall Protection of Human Health and the Environment addresses whether a
remedy provides adequate protection and describes how risks posed through
each pathway are eliminated, reduced, or controlled.
2. Compliance with Applicable or Relevant and Appropriate Requirements
addresses whether a remedy will meet all federal and state environmental laws
and/or provide grounds for a waiver.
Primary Balancing Criteria
The five balancing criteria form the basis of the comparative analysis because they allow
tradeoffs among the alternatives requiring different degrees of performance.
3. Long-Term Effectiveness and Permanence refers to the ability of a remedy to
provide reliable protection of human health and the environment over time.
4. Reduction of Toxicity, Mobility, or Volume Through Treatment refers to the
preference for a remedy that reduces health hazards of contaminants, the
movement of contaminants, or the quantity of contaminants at OU2 through
treatment at the site.
5. Short-Term Effectiveness addresses the period of time needed until protection is
achieved, and any adverse effects to human health and the environment that
may be caused during the construction and implementation of the remedy.
6. Implementability refers to the technical and administrative feasibility of an
alternative or a remedy and the availability of goods and services needed to
implement the alternative.
7. Cost evaluates the estimated capital, operation, and maintenance costs of each
alternative.
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Modifying Criteria
The modifying criteria 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.
6.1 Threshold Criteria
6.1.1 Overall Protection of Human Health and the Environment
The NCP requires that all alternatives be assessed to determine whether they can
adequately protect human health and the environment, in both the short- and long-term,
from unacceptable risks posed by hazardous substances, pollutants, or contaminants
present at the site by eliminating, reducing, or controlling exposures to such substances,
pollutants, or contaminants. Overall protection of human health and the environment
draws on* the assessments of other evaluation criteria, especially long-term effectiveness and
permanence, short-term effectiveness, and compliance with ARARs.
6.1.1.1 Source Area Alternatives
Source Area Alternative 1 (No Further Action) will not be protective because contamination
above ARARs and other performance standards will allow contaminants to migrate offsite
and downward into shallow aquifers, increasing the risks for offsite receptors. All other
source area alternatives will be protective because they prevent migration of contaminants
above performance standards beyond the source area boundary through containment and
collection, and treatment; meet ARARs; prevent exposure to contaminants within the source
area through institutional controls; and monitor the effectiveness of remedial measures.
Source Area Alternative 12 removes soil contamination from depths to which direct
exposure is likely. The inclusion of a surface cap and the encircling vertical barrier of
Source Area Alternatives 11 and 12 will be protective of public health and the environment
by preventing exposure to contaminants, preventing continued leaching of soil
contaminants to groundwater, and preventing further migration of contaminants in excess
of drinking water standards to the non-source area. Source Area Alternative 5 will reduce
the rate at which contaminants would be transported to the non-source area in
groundwater, but may not fully contain the contaminants.
6.1.1.2 Non-Source Area Alternatives
Non-Source Area Alternative 1 will not be protective because contamination will continue
to migrate resulting in enlargement of the non-source area contaminant plume. All other
non-source area alternatives will be protective, because they will prevent further migration
of contaminants above performance standards beyond the boundary of the non-source area
through hydraulic containment and collection and treatment; meet ARARs; prevent
exposure of contaminants within the non-source area boundary through use of institutional
controls; monitor for vertical and horizontal migration of contaminants; and monitor the
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effectiveness of remedial measures. Non-source area Alternative 5, consisting of
conventional pump and treat, provides the greatest degree of certainty for hydraulically
capturing contaminants and treating to protective levels before discharge. Air sparging
(Non-Source Area Alternatives 3 and 7] is not a proven technology at the field scale and the
hydrogeology at OU2 is complex. Contaminated water flowing from springs and seeps
will be captured and treated by all non-source area alternatives.
6.1.2 Compliance with ARARs
Applicable requirements are those cleanup standards, standards for control, and other
substantive requirements, criteria, or limitations promulgated under Federal or State law
that specifically address a hazardous substance, pollutant, contaminant, remedial action, or
location at a CERCLA site. Relevant and appropriate requirements are similar
requirements, that, while not applicable, clearly address problems or situations sufficiently
similar to those encountered at a CERCLA site such that their use is well suited to the
particular site. Compliance with ARARs for the source and non-source area alternatives are
discussed in the following subsections.
Each alternative is assessed to determine whether they would attain applicable or relevant
and appropriate requirements under federal environmental laws and state environmental
or facility siting laws or provide grounds for invoking an ARARs waiver. The ARARs for
alternatives at OU2 are presented in Appendix A. Compliance with some key ARARs is
discussed in the description of alternatives and will not be repeated here.
6.1.2.1 Source Area Alternatives
Source Area Alternative 1 will not meet ARARs, which are groundwater restoration goals,
within a reasonable time frame, given the circumstances of the site. Source Area
Alternative 1 will be considered no further in this Record of Decision. All of the other
alternatives are currently expected to meet chemical-specific ARARs for organic compounds
in groundwater by the time the remedial action is completed. However, it is uncertain that
the treatment technologies proposed can meet the clean up standards in the source area,
particularly for TCE.
Other technologies may be used to extract greater amounts of DNAPL and/or enhance in
situ treatment. Treatability studies will be conducted prior to full-scale use to verify the
technology will fulfill its performance expectations at OU2. While a waiver to chemical-
specific ARARs, specifically TCE and other VOCs within the DNAPL, is not contemplated
at this time, it may be needed in the future to address restoration goals for groundwater in
the OU2 source area.
All Source Area Alternatives would meet action-specific ARARs. Action-specific Federal
and State ARARs are similar for the source area alternatives because the site activities are
similar (monitoring, well drilling, groundwater pumping, offsite incineration of DNAPL,
groundwater treatment, and discharge of water treated at the SRS to the IWTP). Monitoring
will meet the requirements of 40 CFR Part 264 Subpart F [UAC R315-8-6]. Discharges from
the IWTP meet ARARs through compliance with the IWTP pre-treatment permit issued by
the North Davis County Sewer District. Air emissions from the steam stripper in the SRS
are treated by vapor phase carbon and comply with substantive requirements under
national primary and secondary air quality standards [40 CFR Part 50; UAC R307-1-3] and
NESHAPs standards [40 CFR Part 61; UAC R307-10] which regulate specific volatile organic
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compounds, including TCE. The requirement to treat vapors from the air stripper is based
on a Best Available Control Technology (BACT) analysis under UAC R307-1-3.
Source Area Alternatives 5,11, and 12 include excavation of soils. The Source Area and area
immediately adjacent needed for construction will be defined as CAMU. Soils from
construction will be kept within the CAMU and will not trigger the LDRs. The excess soils
will be replaced onsite to serve as the grading layer to establish proper slopes for the
surface cap. The LDRs would otherwise be applicable to excavated soils which contain TCE
or other spent solvents.
All alternatives will meet location-specific ARARs. All proposed siting of waste
management units will be outside of the 100-year floodplain and will comply with the
siting ARAR in 40 CFR Section 264.18 (UAC R315-8-2.9). No jurisdictional wetlands occur
within OU2.
6.1.2.2 Non-Source Area Alternatives
Non-Source Area Alternative 1 will not meet the ARARs which are ground water restoration
goals within a reasonable time frame. Non-Source Area Alternative 1 will be considered no
further in this Record of Decision. All of the other Non-Source Area Alternatives will meet
chemical-specific ARARs, including groundwater restoration goals, within restoration time
frames which are reasonable given the circumstances of the site.
All of the Non-Source Area Alternatives will comply with action-specific ARARs. Action-
specific Federal and State ARARs are similar for the non-source area alternatives because
the site activities are similar (monitoring, well drilling, groundwater pumping, treatment of
groundwater or seeps and springs by air stripping or granular activated carbon, and
discharge of treated water). Emissions from the air stripper must comply with substantive
requirements set under national primary and secondary air quality standards [40 CFR Part
50; UAC R307-1-3] and NESHAPs standards [40 CFR Part 61; UAC R307-10] which regulate
specific volatile organic compounds, including TCE. The requirement to treat vapors from
the air stripper will also be based on a Best Available Control Technology (BACT) analysis
under UAC R307-1-3.
Discharge options, after necessary treatment, include piping water to the IWTP, discharge
to the sanitary sewer where it will be treated further at the Central Weber Sewer
Improvement District, or onsite discharge to a surface drainage or storm sewer.
Compliance with ARARs for SRS discharge is as described for the Source Area Alternatives.
The other two discharge options are onsite actions regulated under the NPDES/UPDES [40
CFR Part 122; UAC R317-8] requirements of the Clean Water Act. Discharge to the sanitary
sewer must meet the substantive pre-treatment requirements set by the POTW. Discharge
to an onsite surface drainage will meet the substantive UPDES requirements.
The Non-Source Area complies with location-specific requirements which are applicable or
relevant and appropriate. None of the Non-Source Area Alternatives would require siting
of hazardous waste management units within the 100-year floodplain and will comply with
the siting ARARs [40 CFR Part 264.18 and UAC R315-8-2.9]. The OU2 site is not located
within an area that contains jurisdictional wetlands.
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6.2 Primary Balancing Criteria
6.2.1 Long-Term Effectiveness and Permanence
The alternatives were assessed for the long-term effectiveness and permanence they afford,
along with the degree of certainty that the alternative would prove successful. Factors that
were considered include the following:
The magnitude of residual risk from untreated waste or treatment residuals
remaining at the conclusion of the remedial activities.
The adequacy and reliability of controls such as containment systems and
institutional controls that are necessary to manage untreated waste and
treatment residuals.
6.2.1.1 Source Area Alternatives
Source Area Alternatives 11 and 12 are comparable and offer the highest degree of long-
term effectiveness and permanence. They would remove as much or more contamination
than Source Area Alternatives 4 and 5. The shallow excavation proposed for Source Area 12
would also remove contamination to a depth where exposure to contaminants would be
unlikely if land use changes in the future. The encircling vertical barrier and cap element
will reliably prevent further contamination in excess of the drinking water standards from
migrating into the non-source area. Exposure to any surfitial contaminants will be
mitigated by a surface cap in both Source Area Alternatives 11 and 12. The residual risk
after remediation for these alternatives ranges from a low of 7.2 x 10* to a high of 2.4 x 10*.
Source Area Alternatives 4 and 5 will reduce contaminant concentrations. However, these
alternatives do not have an encircling vertical barrier and could allow contaminant
migration to the Non-Source Area. Source Area Alternative 5 provides, a vertical wall on
only the down gradient side and would need to be supplemented with pumping wells to
assure effective containment. Source Area Alternative 4 would rely strictly.on hydraulic
containment and is the least certain. Source Area Alternatives 4 and 5 will have a residual
risk, after remediation, that ranges from a low of 3.7 x 10* to a high of 1.1 x 10"*.
All of the alternatives will require long-term management. Institutional controls consisting
of deed and water rights restrictions, as well as access restrictions consisting of fencing and
signs will be implemented to prevent uncontrolled construction in the contaminated media,
use of shallow contaminated groundwater, and unauthorized access to remedial
equipment. These controls will result in limiting future potential exposure pathways and
prevent the area from being used for residential purposes. The long-term effectiveness of
institutional controls in the source area depends on cooperation of other governmental
entities.
6.2.1.2 Non-Source Area Alternatives
Non-Source Area Alternative 5 offers the greatest degree of long-term effectiveness and
permanence, because it will result in the least residual TCE contamination, as compared to
the other non-source area alternatives and is an established technology. Non-Source Area
Alternatives 3 and 7 will be expected to leave residual contamination. Air Sparging is not a
proven technology at the field scale. Non-Source Area Alternative 3, unlike Non-Source
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Area Alternatives 5 and 7, will not have a hydraulic barrier to prevent untreated
groundwater from leaving the non-source area and migrating towards residences. All of
the non-source area alternatives, with the exception of Non-Source Area Alternative 1, will
result in residual risks within the 1 x 10"* to 1 x 10** range.
Institutional controls consisting of restricting new water rights, as well as access restrictions
consisting of fencing and signs have been implemented to prevent uncontrolled access to
the contaminated media, use of shallow contaminated groundwater, and unauthorized
access to remedial equipment. These controls will result in limiting potential exposure.
The long-term effectiveness of institutional controls in the non-source area depends on
cooperation of property owners and municipalities as well as other governmental entities.
6.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
The degree to which alternatives employ treatment to reduce toxicity, mobility or volume at
the site is assessed and considers the following factors:
the treatment processes the alternatives employ and materials they would treat
the amount of hazardous substances, pollutants, or contaminants that would be
destroyed, or treated
the degree of expected reduction in toxitity, mobility, or volume of the waste
from treatment and the specification of which reduction(s) would be occurring
the degree to which the treatment would be irreversible
the type and quantity of residuals that would remain following treatment,
considering the persistence, toxicity, mobility, and propensity to bioaccumulate
of such hazardous substances and their constituents
the degree to which treatment would reduce the inherent hazards posed by
principal threats at the site
6.2.2.1 Source Area Alternatives
All Source Area Alternatives reduce the volume of contaminants at the site. Source Area
Alternatives 11 and 12 are comparable and provide the best overall reduction in toxicity,
mobility, and volume through treatment at the site. Source Area Alternative 12 removes
contaminated shallow soils, providing a greater reduction in the volume of contaminants
than Source Area Alternative 11. Installation of an encircling vertical barrier and surface
cap such as in Source Area Alternative 11 provides greater reduction in the mobility of the
contaminants. Contaminants in shallow soils will not be treated in Source Area
Alternative 11. However, the installation of a surface cap will reduce the mobility of these
contaminants and prevent exposure at the surface.
DNAPL and dissolved contaminants removed from the subsurface will be permanently
destroyed or treated. Use of SVE technology to treat contaminated soil has been successful
at sites contaminated with VOCs. Possible enhancements to SVE to increase its
effectiveness will require treatability studies. The contamination in the top portion of the
Alpine Formation in the immediate area of the current location of the DNAPL could include
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localized pools and pockets or low-permeability lenses of sand and silt that could escape
treatment because of preferential flow paths in the subsurface. These areas will receive
minor reductions in toxicity.
Source Area Alternative 5 provides greater control over contaminant mobility than Source
Area Alternative 4. However, Source Area Alternatives 4 and 5 will not fully address the
mobility of contaminants because an encircling vertical barrier and surface cap are not
proposed.
6.2.2.2 Non-Source Area Alternatives
Non-Source Area Alternative 5 provides the greatest reduction in toxicity, mobility, and
volume. The principal threats to human health and the environment will be addressed by
extracting contaminants from the groundwater and water flowing from springs and seeps.
Groundwater extraction and treatment is a reliable, extensively used technology. It is
expected that this alternative will meet remedial action objectives.
Non-Source Area Alternatives 3 and 7 are ranked as less effective than Non-Source Area
Alternative 5 in removing contaminants from groundwater because they rely on in situ
technologies for treatment. Air sparging is not a proven technology in the field. Additional
process units may be required to treat extracted water and air emissions, adding to the
complexity and potentially lowering the reliability of the system.
6.2.3 Short-Term Effectiveness
Factors that were considered include the following four features as components of short-
term effectiveness:
short-term risks to the community during implementation
potential impacts to worker during implementation
potential environmental impacts during implementation
time until protection is achieved
6.2.3.1 Source Area Alternatives
Source area alternatives will result in minimal additional exposure risks to the community,
workers, or the environment. Shallow groundwater will be extracted and treated in closed
vessels. Source Area Alternative 4 will afford the highest degree of short-term effectiveness
because no soil excavation will be required; hence less dust and traffic will be generated.
Source Area Alternatives 5 ranks next and then Source Area Alternatives 11 and 12 on the
basis of the degree of excavation required. Increased excavation increases the amounts of
dust and traffic and provides greater potential for impacting site workers. However, the
actual increased risk from excavation is expected to be low. Source Area Alternative 12 may
require workers to be in an excavation that is approximately 20 feet deep.
Activities will not generally require workers to be in confined spaces or in deep trenches or
excavations. A plan detailing health and safety procedures will be implemented and will
meet the requirements of the Occupational Safety and Health Administration under 29 CFR
1910.120. Construction will also require dust suppression, if needed. Because activities are
on HAFB, little or no adverse effects are expected for the adjacent community.
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None of the source area alternatives will have adverse environmental impacts. There are no
environmentally sensitive areas such as critical habitats located in OU2. No threatened or
endangered species reside on HAFB. Source area alternatives 4,5,11 and 12 have
comparable construction periods (12 to 24-months) and operations testing before initial
protectiveness is achieved.
6.2.3.2 Non-Source Area Alternatives
The least amount of construction is associated with Non-Source Area Alternative 5, so it
performs best in offering the least potential short-term risks to the community and site
workers because the traffic and dust generation is the least. Non-Source Area
Alternatives 3,5, and 7 are comparable due to the similarity of activities. Potential risks to
the community are expected to be minimal for all Non-Source Area Alternatives because
the contamination is in mostly agricultural areas with very little residential development.
The initial phase of installation of groundwater extraction wells or trenches will be installed
near the leading edge of the TCE plume. This area is several hundred feet away from the
nearest residence.
Implementation of Non-Source Area Alternatives 3,5, and 7 will have minimal potential
impacts to workers since most activities will be limited to installation of extraction wells or
trenches and installation of pipelines to carry contaminated groundwater to a treatment
facility arid/or IWTP. Health and safety procedures will be implemented and will meet the
requirements of the Occupational Safety and Health Administration under 29 CFR 1910.120.
There is a minimal potential to create environmental impacts during implementation.
Non-Source Area Alternatives 3,5, and 7 offer comparable and acceptable time frames until
initial protectiveness is achieved. Groundwater extraction and treatment will begin
operation within 12 to 18 months after the commencement of construction.
6.2.4 Implementability
The ease or difficulty of implementing the alternatives was assessed by considering the
following types of factors:
technical feasibility, including technical difficulties and unknowns associated
with the construction and operation of a technology, the reliability of the
technology, ease of undertaking additional remedial actions, and the ability to
monitor the effectiveness of the remedy
administrative feasibility, including activities needed to coordinate with other
offices and agencies and the ability and time required to obtain any necessary
approvals and permits from other agencies
the availability of services and materials, including the availability of adequate
offsite treatment, storage capacity, and disposal capacity and services; the
availability of necessary equipment and specialists, and provisions to provide
any additional resources; the availability of services and materials; and the
availability of prospective technologies
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6.2.4.1 Source Area Alternatives
All of the Source Area Alternatives share the technical uncertainty of remediating DNAPL
to the extent groundwater is permanently restored and protected against future
contamination through leaching. While a waiver to chemical-specific ARARs or risk-based
concentrations is not contemplated at this time, it may be considered for the future.
Uncertainties exist in limitations to potential technologies, complex hydrogeology, and
contaminant-specific factors.
All Source Area Alternatives are comparable in administrative implementability. The key
treatment facility is the SRS which is already functional and operating within discharge
limits set by ARARs and the pre-treatment permit conditions upon the IWTP. No
additional permits would be required. Because the Source Area is exclusively on-Base,
access issues are minimal.
Distinctions between the Source Area Alternatives are mainly in the context of technical
feasibility. Source Area Alternative 4 is the most implementable because pumping well
systems are easily installed and modified. The necessary materials, equipment, and
expertise are readily available and no vertical barrier would be constructed. The large
amounts of groundwater are within the capacities of the SRS and the IWTP, but pipeline
modifications may be needed. Alternatives 5,11, and 12 follow respectively in the ranking.
The goods and services are available, but the degrees of construction, trenching, and
amounts of materials handled increase progressively. Because Source Area Alternatives 11
and 12 propose encapsulation, substantially less shallow groundwater would need to be
extracted and treated. Prospective innovative technologies are considered comparable in
terms of materials, equipment, and expertise needed.
6.2.4.2 Non-Source Area Alternatives
No significant implementability problems are foreseen for the non-source area alternatives.
All are comparable in terms of: (1) availability of goods and services; (2), similar access
issues to private property; (3) constraints of topography on the steep hillside just off-Base;
and (4) administrative feasibility in terms of complying with ARARs and/or permit
requirements for discharges of treated water. Non-Source Area Alternative 5 is considered
the most implementable because pump and treat is an established, reliable technology
which can be readily modified if needed. Air sparging is considered less reliable and less
easily modified because the technologies are not proven at the field scale. Because of this,
Non-Source Area Alternative 7 would rank next, followed by Non-Source Area
Alternatives.
6.2.5 Cost
The types of costs that were evaluated include the following:
capital costs, including both direct and indirect costs
annual operation and maintenance cost
net present value of capital and operation and maintenance ( a 30-year period is
used to calculate the present worth costs)
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6.15.1 Source Area Alternatives
Source Area Alternatives 4,5,11,12 all have comparable total present worth costs; however,
the distribution of capital and operation and maintenance costs varies considerably. Source
Area Alternative 12, because of the proposed soil excavation, has a capital cost over twice as
high as the nearest alternative, but also a substantially lower operation and maintenance
cost because soil flushing is less expensive to operate than in-situ steam stripping or other
technologies. Source Area Alternative 11 has a significantly lower operation and
maintenance cost compared to Source Area Alternatives 4 and 5 because it does not require
the nearly continuous operation of a shallow groundwater extraction and treatment system.
Table 6-1 summarizes the costs associated with each source area alternative.
6.2.5.2 Non-Source Area Alternatives
Non-Source Area Alternatives 3 and 7 have the highest estimated costs; Non-Source Area
Alternative 5 is substantially less expensive than these alternatives, with Non-Source Area
Alternative 1 having the least cost. The primary difference in costs between Non-Source
Area Alternatives 3 and 7 versus 5 is the capital costs. The lower capital cost is a direct
result of Non-Source Area Alternative 5 not requiring the lengthy trench or extraction wells
for the air stripping system. Onsite discharge to a surface stream in Non-Source Area
Alternatives 5 and 7 may lower costs. For the purpose of evaluation, this option is applied
uniformly to all of the Non-Source Area Alternatives (except Non-Source Area
Alternative 1) and does not make any alternative more cost effective than another.
Table 6-1 summarizes the cost of each non-source area alternative.
6.3 Modifying Criteria
6.3.1 State Acceptance
The State of Utah agrees with the selected remedy. No change to the selected remedy is
necessary.
6.3.2 Community Acceptance
A public meeting on the Proposed Plan was held on May 25,1994. No comments were
received from the public specifically agreeing with or opposing components of the
preferred alternative. The concerns expressed related to location of residents relative to
OU2 and contaminated springs and seeps, property values, risk assessment factors,
potential health effects of site contaminants, and the schedule of the remedial action. These
are further discussed in the Responsiveness Summary, which is part of this ROD.
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Table 6-1
Summary of Costs for OU2 Source and Non-Source Area Alternatives
Source Area Alternatives
1
4
5
11
12
Non-Source Area
Alternatives
1
3
5
7
Capital Cost
$28,000
$2,738,000
$4,994,000
$6,897,000
$14,234,000
$130,000
$9,300,000
$5,100,000
$8,700,000
Annual Operation and
Maintenance Cost
$27,000
$2,329,000
$2,376,000
$2,012,000
$740,000
$172,000
$1,160,000
$610,000
$950,000
Total Present
Worth Cost
$450,000 1
$19,137,000 j
$22,118,000 1
$20,910,000 |
$24,070,000 1
52,778,000
517,900,000
511,000,000 j
517,000,000
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7. THE SELECTED REMEDY
7.1 Description of the Selected Remedy
The selected remedy at HAFB OU2 is the combination of Source Area Alternative 11 and
Non-Source Area Alternative 5. Under the selected remedy for OU2, contamination in
groundwater, springs and seeps, and soil will be addressed. This remedy includes the
interim action implemented in 1993 in the Source Area with the objective of extracting as
much DNAPL as practicable. In the Non-Source Area, the remedy includes the prior
response actions consisting of providing alternate water supplies and collection, and
treatment of contaminated seeps and springs.
Elements of the remedy common to both the Source Area and Non-Source Area include:
Groundwater from the Non-Source Area and Source Area will be pumped to the
SRS for any necessary treatment. However, as concentrations change in time, it
, may become more cost effective to use other onsite discharge options. Other
options, after necessary treatment, include discharge to the sanitary sewer where
it will be treated further at the Central Weber Sewer Improvement District, or
onsite discharge to a surface drainage or storm sewer. Water collected from
seeps and springs may be added to the groundwater stream for treatment or
may continue to be treated and discharged to the surface immediately at the site.
Long-term monitoring for contaminants and treatment system performance. A
performance and compliance sampling program (PCSP) will be implemented
during the remedial action to monitor performance and compliance with
remediation goals. This program will include locations of performance
monitoring points, monitoring frequency, analytical parameters, sampling and
analytical methods, and statistical methods for evaluating data.
Institutional controls to prevent completion of potential exposure pathways or to
protect facilities installed as part of the remedy. The institutional controls are
described in Section 5.2 of this ROD. Institutional controls have already been
applied to the future use of groundwater.
Residuals management: Granular activated carbon filters may be used to
remove contamination from groundwater and water from springs and seeps
(when flowing) or organic vapors from air or steam stripping operations. After a
granular activated carbon filter is used for the last time, it will be regenerated or
disposed at an offsite permitted facility.
Because the selected remedy will result in hazardous substances remaining
onsite above health-based levels, a review will be conducted within 5 years after
commencement of the remedial action to ensure the remedy continues to
provide adequate protection of human health and the environment.
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Elements specific to the Source Area (Alternative 11) include:
A vertical barrier to encircle the DNAPL and associated highly contaminated
groundwater in the Source Area. The vertical barrier will hinder contamination
from moving into the non-source area, as well as decrease the inflow of
uncontaminated groundwater into the contained area. This barrier will be keyed
into the low-permeability clays and silts underlying the shallow aquifer in the
source area.
A surface cap will be constructed to decrease the inflow of precipitation and
prevent erosion of surface soils by wind and water. The surface cap will also
prevent human contact with surface soil contamination which may result from
remedial activities.
DNAPL and contaminated groundwater will continue to be pumped from
extraction wells to the SRS for treatment. DNAPL will be separated by gravity
and the organic phase incinerated at a permitted facility off-Base. The water
. phase will be treated by steam stripping. Air stripping will be added to the
treatment process to increase the capacity to address the load of contaminants
and to maintain compliance with IWTP pretreatment requirements.
Soils in the source area will be treated by SVE. The source area will be de-
watered to operate SVE in what is currently the saturated zone.
Planned treatability studies include in-situ steam stripping and surfactant
flushing in the DNAPL zone.
The Source Area and area immediately adjacent needed for construction will be defined as a
Corrective Action Management Unit. Soils from construction will be kept within the
CAMU and will not trigger the Land Disposal Restrictions. It is expecte4 that most soils
excavated would comply with the LDRs regardless because they will be consolidated
within the Area of Contamination. The excess soils will be replaced onsite to serve as the
grading layer to establish proper slopes for the surface cap.
Changes in groundwater levels due to the installation of the vertical barrier may present
concerns for slope stability or the integrity of the vertical barrier wall. Additional
groundwater level controls may be needed.
The goal of this remedial action is to restore the shallow groundwater to its beneficial use.
At this site, the shallow groundwater is a potential drinking water source. However, there
is no current use of the shallow groundwater in the Source Area. Groundwater
contamination may be especially persistent in the Source Area, where free phase and
residual DNAPL exist and concentrations are high. The ability to achieve cleanup levels at
all points throughout the area of attainment, or plume, cannot be determined until the
extraction system has been implemented, modified as necessary, enhanced by any
promising innovative technologies, and contaminant levels monitored over time. If the
selected remedy cannot meet the specified remediation levels at any or all of the monitoring
points during implementation, the contingency measures and objectives described in this
section may modify the selected remedy and remediation levels for these portions of the
plume. Such contingency measures will at a minimum prevent exposure with a
combination of containment technologies and institutional controls. These contingency
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measures are considered to protect human health and the environment, and are technically
practicable under the corresponding circumstances.
The selected remedy will include groundwater extraction for an estimated period of 30
years, during which time the system's performance will be carefully monitored on a regular
basis and adjusted as warranted by the performance data collected during operation.
Modifications may include any or all of the following:
Discontinuing pumping at individual wells where cleanup goals have been
attained, but monitoring will continue for up to 5 years to assure cleanup goals
have been attained
Alternating pumping at wells to eliminate stagnation points
Pulse pumping to allow aquifer equilibration and encourage adsorbed
contaminants to partition into groundwater
Installing additional extraction wells to facilitate or accelerate cleanup of the
contaminant plume
If it is determined, on the basis of the preceding criteria and the system performance data,
that certain portions of the aquifer cannot be restored to their beneficial use, all of the
following measures involving long-term management may occur, for an indefinite period of
time, as a modification of the existing system:
Engineering controls such as physical barriers or long-term gradient control
provided by low-level pumping, will be maintained as containment measures
Chemical-specific ARARs will be waived for the restoration goals of those
portions of the aquifer based on the technical impracticability of achieving
further contaminant reduction
Institutional controls will be provided and maintained to restrict access to those
portions of the aquifer that remain above remediation levels
Monitoring of specified wells will continue
Remedial technologies for groundwater restoration will be periodically re-
evaluated
The decision to invoke any or all of these measures may be made during a periodic review
of the remedial action, which will occur at least every five years in accordance with
CERCLA Section 121 (c).
Elements specific to the Non-Source Area (Alternative 5) include:
Contaminated shallow groundwater will be pumped from a trench and/or
extraction wells to the SRS for treatment. The initial phase will intercept the
outer portion of the plume and additional monitoring will be used to estimate a
remedial time frame. Complex hydrogeology makes accurate modeling difficult;
time frames range from 15 to over 30 years. Additional extraction systems will
be installed in the plume if the monitoring results indicate an excessive
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remediation time frame, such as more than 30 years. To provide a more accurate
restoration time frame modeling and/or empirical estimates will be presented
no later than five years from the commencement of remedial action.
Water flowing from each contaminated spring and seep location will be
collected, treated, and discharged. The seeps and springs at OU2 are fed by
groundwater and flow rates vary with climatological conditions. Extracting
groundwater may also influence the flow rates. The treatment system for the
seeps and springs will be operated whenever there is sufficient flow to operate
the system.
The goal of this remedial action for the Non-Source Area is to restore shallow groundwater,
and the hydrologically connected seeps and springs, to beneficial use. Shallow
groundwater and water from the seeps and springs is a potential drinking water source.
However, there is no current domestic use of the shallow groundwater in the vicinity of the
OU2 Non-Source Area plume. There is limited agricultural use currently addressed by
alternate water supplies. Based on information in the Remedial Investigation and
Feasibility Studies, the selected remedy will achieve this goal.
The selected remedy for the Non-Source Area will include groundwater extraction for an
estimated period of 30 years, during which the systems performance will be carefully
monitored on a regular basis and adjusted as warranted by the performance data collected
during operation. Modifications may include any or all of the following:
discontinuing pumping at individual wells where cleanup goals have been
attained, but monitoring will continue for up to 5 years to assure cleanup goals
have been attained
alternating pumping at wells to eliminate stagnation points
pulse pumping to allow aquifer equilibration and encourage adsorbed
contaminants to partition into groundwater *
installing additional extraction wells to facilitate or accelerate cleanup of the
contaminant plume
It may become apparent, during implementation or operation of the groundwater extraction
system and its modifications, that contaminant levels have ceased to decline and are
remaining constant at levels higher than the remediation goal over some portion of the
contaminated plume. In such a case, the system performance standards and/or the remedy
may be re-evaluated.
7.1.1 Remediation Goals and Performance Standards
The goals of this remedial action are described for each of the three media of concern in the
following section. The performance of the remediation system, with respect to meeting the
remediation goals, will be monitored according to the performance monitoring plan to be
developed during the remedial design. The remedial action includes the ongoing response
actions that have been implemented at OU2.
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The remedial action goals for OU2 groundwater, soil and springs and seeps are:
Meet chemical-specific ARARs. Restoration goals are drinking water MCLs.
Meeting MCLs will satisfy restoration goals of the State Groundwater Quality
Protection Rule.
Limit cancer risk to less than ICT* with a target of 10"6 due to incidental ingestion,
dermal contact, or inhalation of vapors.
Maintain contaminant concentrations low enough to avoid chronic health effects
(as indicated by a hazard index of less than one).
Prevent further degradation of groundwater quality in accordance with the Utah
Corrective Action Cleanup Policy for CERCLA and UST Sites.
Remediate groundwater, water flowing from springs and seeps, source
contaminants, and soil in a timely manner in compliance with the selected
remedy to achieve remedial action goals.
The long-term remediation objective for the DNAPL-contaminated zone is to remove the
free-phase, residual, and vapor phase DNAPL to the extent practicable and contain DNAPL
sources that cannot be removed. It may be difficult to locate and remove all of the
subsurface DNAPL. Additionally, there is uncertainty in the ability of the technology to
meet MCLs. If successful in remediation goals, the selected remedy would result in a
residual risk that ranges from a low of 7.2 x 10"8 to a high of 2.4 x 10*.
The area of attainment over which these cleanup goals are to be achieved is defined as that
portion of the groundwater and locations of springs and seeps where MCLs are exceeded.
The area of attainment for groundwater is the area where TCE exceeds its MCL (5 ^g/1).
The area of attainment for soil is the area where contaminated soils exceed the risk-based
cleanup level. Other chemicals in groundwater that may exceed their MCLs are within this
defined area.
Table 7-1 presents the list of COCs and remediation goals. In summary, PCE and TCE were
retained as COCs requiring remediation in soils. PCE, DCE, methylene chloride, TCA, and
TCE were retained as COCs requiring remediation in shallow groundwater in the Source
Area and Non-Source Area. Toluene and the pesticides beta-BHC and gamma-BHC were
retained as contaminants requiring remediation in groundwater in the source area only.
Other chemicals present were not considered COCs because of the low-risks posed, the data
was questionable, or the detections were not believed to be site-related. The questionable
data included detections by analytical methods suited for water but modified to detect
contaminants in soils. Some metals in groundwater in older wells appeared to be elevated
due to well construction or high turbidity. The distribution and concentration of most
pesticides do not suggest they are site related and risks presented by these are within the
acceptable risk range.
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Table 7-1
Chemicals of Concern
and
Remediation Goals for HAFB Operable Unit 2
Chemical of Concern
Ground and Surface Water
1,2-Dichloroethene
Methylene Chloride (a)
Tetrachloroethene
1,1,1-Trichloroethane
Trichloroethene
Toluene
Beta-BHCa)(in source area only)
Gamma-BHC (Lindane) (in source area only)
Soil and Sediment
Tetrachloroethenela>
Trichloroethenela>
Cleanup Standards6'
Concentration
70 us/1
6 HR/1
5 UK/1
200 ws/1
5 UK/1
1,000 UK/1
0.010 jig/1
0.2 UK/1
1231mK/kK
58.21 mK/kK
(a) Remediation goals for these chemicals are risk-based levels
(b) Unless otherwise specified, the concentrations for ground and surface water are maximum
contaminant levels (MCLs) established under the Safe Drinking Water Act and /or Utah Primary
Drinking Water Standards
7.1.2 Restoration Time Frame
The restoration time for groundwater is estimated to be greater than 30 years in the Source
Area and may range from 15 to 30 years in the Non-Source Area. The restoration time for
springs and seeps is estimated to be 15 years. Complex hydrogeology precludes accurate
modeling with the information available. Installation of the pumping systems will provide
more hydrogeological and empirical information by which better estimates may be
accomplished. The SVE treatment of contaminants in the source area is estimated to be
greater than 30 years, although other technologies such as steam injection, surface flooding,
or other technologies could substantially reduce this time. Treatability studies will be
required to determine the effectiveness of other technologies.
7.1.3 Costs
The estimated capital cost for remediating OU2 using the selected remedy (Source Area
Alternative 11 and Non-Source Area Alternative 5) is presented in Table 7-2. The total
capital cost for the selected remedy is estimated at $11,997,000. The selected remedy
includes the following capital costs items: an encircling vertical barrier and surfactant cap,
a shallow groundwater extraction and treatment system, for the source area, an SVE system
for the source area, a shallow groundwater extraction system for the non-source area with
onsite treatment and discharge to the IWTP and/or POTW, and collection, treatment, and
onsite discharge of springs and seeps.
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Operation and maintenance costs have been calculated for a 30-year period and do not
reflect costs that may be incurred if the remediation period lasts longer than 30 years.
Annual operation and maintenance for the selected remedy is estimated to be $2,622,000.
The total 30-year present worth cost of the selected remedy, using an interest rate of 5
percent, was estimated at $31,910,000. The present worth cost is estimated with a +50/-
30 percent accuracy for the 30-year period.
Table 7-2
Summary of Costs for the Selected Remedy at HAFB Operable Unit 2
Alternative
Source Area Alternative 11
Non-Source Area Alternative 5
Total Cost
Capital Cost
56,897,000
55,100,000
511,997,000
Annual
Operation and
Maintenance
$2,012,000
5610,000
$2,622,000
Total Present
Worth Cost
$20,910,000
511,000,000
$31,910,000
7.2 Statutory Determinations
The selected remedy for HAFB OU2 meets the statutory requirements of Section 121 of
CERCLA as amended by SARA. These statutory requirements include protectiveness of
human health and the environment, compliance with ARARs, cost effectiveness, utilization
of permanent solutions and alternative treatment technologies to the maximum extent
practicable, and preference for treatment as a principal element. The manner in which the
selected remedy for OU2 meets each of the requirements is presented in the following
discussion.
7.2.1 Protection of Human Health and the Environment
The selected remedy for OU2 protects human health and the environment through the
following treatments with engineering and institutional controls:
Groundwater will be collected and treated onsite until contaminant
concentrations meet drinking water MCLs and to reduce carcinogenic and
noncarcinogenic risks to within acceptable ranges. The residual risk after
remediation is estimated to range from a low of 7.2 x 10"1 to a high of 2.4 x 10*.
Institutional controls, including well advisories and water rights and well
drilling restrictions, and easements and leases as necessary for monitoring and
installation of equipment, will be enacted.
Water flowing from contaminated springs and seeps will be collected and
treated onsite until contaminant concentrations meet drinking water MCLs and
are within an acceptable range for both carcinogenic and noncarcinogenic risks.
The source of contaminants, former Chemical Disposal Pit 3, will be
encapsulated by an encircling vertical barrier and a surface cap to prevent
further migration to shallow groundwater. The contaminated groundwater in
the encapsulated area will be treated by groundwater collection and treatment.
SLORME70158.FORNAL\ROORNALDOC
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Soil in the encapsulated area will be treated by in-situ soil vapor extraction.
Institutional controls will help prevent exposure by restricting groundwater and
land use.
Ongoing monitoring of groundwater, water flowing from springs and seeps, and
soil will provide the basis of determining the effectiveness of the remedial
action. It will also allow for the evaluation of whether the goal of meeting the
estimated residual risks will be met.
The selected remedy will not pose any unacceptable short-term risks. Institutional controls
and proper health and safety procedures will be implemented during construction and
monitoring to minimize short-term risks to site workers and off-Base residents. The
selected remedy will minimize cross-media impacts. For example, contamination of
groundwater will be reduced by remediating the area near former Chemical Disposal Pit 3,
thus reducing impacts on springs and seeps fed by shallow groundwater.
Because this remedy will result in hazardous substances remaining onsite above health-
based levels, a review will be conducted within 5 years after commencement of remedial
action to ensure that the remedy continues to provide adequate protection of human health
and the environment.
7.2.2 Compliance with Applicable or Relevant and Appropriate Requirements
Section 121(d)(l) of CERCLA, as amended by SARA, requires that the remedial actions for
OU2 must attain a degree of cleanup that assures protection of human health and the
environment. In addition, remedial actions that leave any hazardous substances,
pollutants, or contaminants onsite must, upon completion, meet a level or standard that at
least attains ARARs under the circumstances of the release. All ARARs will be met upon
completion of the selected remedy or a waiver will be available. Federal and State ARARs
for the selected remedy are presented in Appendix A.
Chemical-Specific ARARs. The selected remedy will comply with chemical-specific ARARs
related to groundwater, seeps and springs, air quality, and discharge limits from water
treatment.
MCLs based on the Safe Drinking Water Act (Utah Primary Drinking Water Regulations)
are relevant and appropriate as cleanup standards for contaminated groundwater and
springs and seeps at OU2. The Utah Groundwater Quality Protection Rule provides
identical standards for the chemicals of concern. While a waiver of MCLs as restoration
goals for groundwater in the Source Area is not contemplated at this time, it may be
contemplated in the future.
Water discharged from the SRS currently complies with chemical-specific pre-treatment
conditions of the HAFBIWTP which is regulated under a UPDES/NPDES pre-treatment
permit. Under 40 CFR Part 261.4(a)(2), discharges subject to regulation under Section 402 of
the Clean Water Act are exempt from RCRA. Air stripping will be added to the SRS
treatment train to adjust for the increased contaminant load in the water stream. Air
emissions from the SRS are treated by carbon to comply with levels set by air quality
ARARs (NESHAPS, Clean Air Act, Utah Air Quality Rules, Utah Air Conservation Act).
The system is readily modifiable if needed to comply with the added contaminant load on
the carbon. The SVE system will also comply with the same air quality ARARs.
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Location-Specific ARARs. Few location-specific ARARs were identified for this site. The
location standards for hazardous wastes management units are applicable (40 CFR Part
264.18; UAC R315-8-2.9), but no remediation units will be located on a fault or in a 100 year
floodplain.
Action-Specific ARARs. The selected remedy will comply with all action-specific ARARs,
as identified in Tables A-5 and A-6. Federal and State action-specific ARARs include those
for air and water discharges as described under chemical-specific ARARs. Additional
action-specific applicable ARARs include: the Solid Waste Disposal Act (SWDA), RCRA
requirements for treatment, storage, and disposal of wastes generated from construction,
Underground Injection Control, and State ARARs which are more stringent or for which
there are no federal counterparts.
SWDA and RCRA requirements pertain to disposal of the DNAPL and the disposal of
wastes generated from construction of the containment and treatment systems. The
DNAPL is incinerated at an offsite permitted facility in compliance with RCRA.
The Source Area and area immediately adjacent needed for construction will be defined as a
CAMU. Soils from construction will be kept within the CAMU and will not trigger the
LDRs. The excess soils will be replaced onsite to serve as the grading layer to establish
proper slopes for the surface cap. The LDRs would otherwise be applicable to excavated
soils which contain TCE or other spent solvents.
Because the wastes originally disposed in Chemical Disposal Pit 3 were placed before
November, 1980 the RCRA Subpart G landfill closure regulations are relevant and
appropriate to the wastes closed in place and applicable to wastes generated by excavation.
The cap design will comply with the relevant and appropriate requirements for landfills.
Treatability Studies and remedy(ies) which inject substances into the subsurface will
comply with the substantive requirements of the Underground Injection Control
Regulations (40 CFR Section 144-147; UAC R 317-7). The remedy incorporates DNAPL
removal through continued pump and treat, SVE, and the encapsulation of the source area.
The remedy will meet the action-specific requirements of the Utah Groundwater Quality
Protection Rule.
Compliance with the Utah Cleanup Action and Risk Based Closure Standard [UAC R315-
101] will be met with the treatment plus the long-term management provided by
monitoring and institutional controls. Compliance with the Utah Corrective Action
Cleanup Policy for CERCLA and UST Sites [UAC R311-211] will be met through source
control. Other State of Utah action-specific ARARs are identified in Table A-6. These
include standards for which there is no federal counterpart or are more stringent than
federal requirements.
The alternative discharge options are onsite actions regulated under the NPDES/UPDES
(40 CFR Part 122; UAC R317-8) requirements of the Clean Water Act. Discharge to the
sanitary sewer must meet the substantive pre-treatment requirements set by the POTW. If
the onsite treatment satisfies all surface water discharge requirements, the treated water
may be discharged to an onsite stream in compliance with water quality standards (40 CFR
Part 122; UAC R317-8) instead of pumping to the IWTP.
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7.2.3 Cost-Effectiveness
The selected remedy is cost-effective in addressing the principal risks posed by the DNAPL,
soils, ground water, and seeps and springs within a reasonable period of time. Section
300.430(f)(ii)(D) of the NCP requires evaluating cost-effectiveness by comparing all of the
alternatives which meet the threshold criteria against three additional balancing criteria
which describe the alternatives overall effectiveness: long-term effectiveness and
permanence; reduction of toxicity, mobility or volume through treatment; and short-term
effectiveness.
The selected remedy for the Source Area (Alternative 11) provides the best overall
effectiveness of all alternatives considered proportional to its cost. The engineering controls
to contain the highest concentrations of contaminants reduces the scope of long-term
management which would be needed due to the presence of the DNAPL. Transport of
contaminants to the Non-Source Area off-Base is controlled without continually pumping
high quantities of water which would be required by the non-encapsulating alternatives.
Extraction of DNAPL and treatment of soils and groundwater will greatly reduce the
toxicity, mobility, and volume of contaminants at the site. Alternative 12 would provide
greater long-term effectiveness in addressing surface soils. However, risks posed from
direct surface soil exposures are low in both residential and industrial construction
scenarios. The cost increase of 20 percent for Alternative 12 over Alternative 11 is not
justified, particularly since surface exposures will also be controlled in Alternative 11 by the
cap. Also, Alternative 12 offers less short-term effectiveness in terms of worker and
community protection.
The selected remedy for the Non-Source Area (Alternative 5) provides the best overall
effectiveness of all alternatives considered proportionate to its cost. It is the least costly for
capital and operations and maintenance costs of all of the alternatives which meet the
threshold criteria. All alternatives which met the threshold criteria would reduce toxicity,
mobility, and volume. The risks to the community and site worker concerns of short-term
effectiveness are readily addressed. All are implementable. However, the innovative
technologies are not proven at the field scale in terms of contaminant reduction efficiency or
operations and maintenance for groundwater restoration.
7.2.4 Utilization of Permanent Solutions and Alternative Treatment Technologies
The selected remedy meets the statutory requirement to utilize permanent solutions and
treatment technologies to the maximum extent practicable. The selected remedy provides
the best balance of tradeoffs among all the alternatives with respect to the five balancing
criteria which include:
long-term effectiveness
reduction of toxicity, mobility, or volume reduction through treatment
short-term effectiveness
implementability
cost
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The criteria most critical in the selection decision for the Source Area were long-term
effectiveness; implementability; and cost. All alternatives which met the threshold criteria
would reduce toxicity, mobility, and volume. Potential risks to the community and site
worker concerns of short-term effectiveness are readily addressed. Continual pumping of
the large volumes of water needed for Source Area Alternatives 4 and 5 present a costly
long-term management concern which is lessened with the construction of the vertical
barrier. Cost becomes a greater concern considering it may take longer than 30 years to
restore the source area, with corresponding increases in operations and maintenance costs.
Construction of such a barrier is implementable and would contain the highest
concentrations of contaminants.
The criteria most critical in the selection decision for the Non-Source Area were long-term
effectiveness and cost. Conventional pump and treat offers fewer long-term effectiveness
concerns and well and pump systems are readily modified. The selected alternative for the
Non-Source area provides comparable performance at about half the cost estimated for the
air sparging alternatives.
7.2.5 Preference for Treatment as a Principal Element
The selected remedy for OU2 utilizes permanent solutions and treatment technologies to
the maximum extent practicable. The use of SVE (with possible enhancements such an in
situ steam stripping or soil flushing) to remediate contaminated shallow groundwater,
carbon adsorption to treat (or pretreat) extracted groundwater, and treatment of vapors
from the SVE system satisfies the statutory preference for treatment that permanently and
significantly reduces the volume, toxicity, and mobility of hazardous substances. These
treatment processes are expected to permanently reduce the concentrations of
contaminants. The vertical barrier and encapsulation provide permanent solutions in the
event treatment is unable to meet restoration goals.
7.3 Documentation of Significant Changes
The Proposed Plan for HAFB OU2 was released for public comment on May 11,1994. A
public meeting on the Proposed Plan was held on May 25,1994. The Proposed Plan
identified Source Area Alternative 11 and Non-Source Area Alternative 5 as the preferred
combination of alternatives. This remedy included: an encircling vertical barrier and
surface cap; shallow groundwater extraction and treatment; soil vapor extraction; shallow
groundwater extraction and onsite treatment and discharge to the IWTP and POTW;
collection, treatment, and onsite discharge of springs and seeps; and monitoring of shallow
groundwater. The public was informed of the low likelihood of restoring the groundwater
in the on-Base Source Area to drinking water standards. All written and verbal comments
received during the public comment period were reviewed. No changes to the preferred
alternative, as originally presented in the Proposed Plan, were required based on review of
written and verbal comments.
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8. References
CH2M HILL Inc., 1993. Draft Final Addendum to the Feasibility Study for Operable Unit 2.
Hill Air Force Base. Utah, November 1993.
CH2M HILL, Inc., 1994. Final Addendum to the Feasibility Study for Operable Unit 2. Hill
Air Force Base. Utah, February 1994.
National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300.
OSWER Directive 1990. A Guide to Developing Superfund Records of Decision. OSWER
Directive: 9335.B-Q2FS-1, May 1990.
OSWER Directive 1993. Guidance for Evaluating the Technical Impracticability of Ground-
Water Restoration. Interim Final OSWER Directive 9234.2-25, September 1993.
Radian Corporation, 1990. Draft Site Characterization Summary for Operable Unit 2. August
1990.
Radian Corporation, 1991. Draft Memorandum on Remedial Action Objectives for Operable
Unit 2. Hill Air Force Base. Utah. December 1991.
Radian Corporation, 1992a. Draft Assembled Alternatives Screening Memorandum for
Operable Unit 2. Hill Air Force Base. Utah. March 1992.
Radian Corporation, 1992b. Final Baseline Risk Assessment for Operable Unit 2, Hill Air
Force Base. Utah. March 1992.
Radian Corporation, 1992c. Final Remedial Investigation Report for Operable Unit 2. Hill Air
Force Base, Utah. July 1992.
Radian Corporation, 1992d. Draft Detailed Analysis of Alternatives Memorandum for
Operable Unit 2. Hill Air Force Base, Utah. May 1992.
Radian Corporation, 1993a. Draft Addendum to the Feasibility Study Report for Operable
Unit 2. Hill Air Force Base. Utah. February 1993.
Radian Corporation, 1993b. Draft Final Addendum to the Remedial Investigation Report for
Operable Unit 2. Site WP07, SS21. Hill Air Force Base. Utah, December 1993.
Radian Corp., 1994. Final Addendum to the Remedial Investigation for Operable Unit 2. Site
WP07, SS21, Hill Air Force Base. Utah. April 1994.
US. EPA, 1988a. Technology Screening Guide for Treatment of CERCLA Soils and Sludges.
EPA Report No. EPA/540/2-88/004, September 1988.
SLDRME70158.FOF1NAL\ROORNALOOC 8-1
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U.S. EPA, 1988b. Guidance for Conducting Remedial Investigations and Feasibility Studies
Under CERCLA. Interim Final. EPA Report No. EPA/540/G-89/004, October 1988.
U.S. EPA, 1989. Guidance on Preparing Superfund Decision Documents: The Proposed Plan.
the Record of Decision. Explanation of Significant Differences, the Record of Decision
Amendment. Interim Final. EPA Report No. EPA/540/G-89/007, July 1989.
U.S. EPA, 1989. Risk Assessment Guidance for Superfund. Volume I: Human Health
Evaluation Manual (Part A). Interim Final. U.S. EPA Office of Emergency and Remedial
Response. EPA/540/1-89/002, December 1989.
U.S. EPA, 1990. A Guide to Developing Superfund Records of Decision, OSWER Directive:
93353-02FS1, May 1990.
U.S. EPA, 1991a. Superfund Records of Decision Update. EPA Office of Solid Waste and
Emergency Response. Publication 9200.5-2161, May 1991.
U.S. EPA, 1991b. Stabilization Technologies for RCRA Corrective Actions, EPA Report No.
EPA/625/6-91/026, August 1991.
US. EPA,' 1991c. Record of Decision Checklist for Final Remedial Actions. EPA Office of
Emergency and Remedial Response, undated (circa 1991).
US. EPA, 1991d. Record of Decision Checklist for Final Groundwater Action EPA Office of
Emergency and Remedial Response, updated (circa 1991).
U.S. EPA, 1991e. Record of Decision Checklist for Summary of Site Risks in FY91 ROD
Analysis: Final Action, EPA Office of Emergency and Remedial Response, undated (circa
1991).
U.S. EPA, 1993. Compendium of ROD Language for FY93 Focus Areas. EPA Office of Solid
Waste and Emergency Response, EPA/540-R-059 (PB93 963328), April 1993.
U.S. EPA, 1993A. Guidance for Evaluating the Technical Impracticability of Groundwater
Restoration, Interim Final. OSWER Directive 9234.2-25, September 1993.
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9. Responsiveness Summary
Overview
This responsiveness summary provides information about the views of the community with
regard to the proposed remedial action (RA) for Hill Air Force Base (HAFB) Operating
Unit 2 (OU2), documents how public comments have been considered during the decision
making process, and provides responses to concerns.
The public was informed of the selected RA in the following ways:
established USAF, EPA, and State contacts for citizens
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 effected and interested parties prior
to the public comment period
a public comment period was held from May 11,1994, through June 10,1994
a public availability session was held on May 19,1994
a public meeting was held on May 25,1994, at South Weber Elementary School
in South Weber, Utah
written comments by the public were encouraged
The public meeting was well attended and residents voiced numerous concerns about the
nature, extent, and risks associated with the contamination. A transcript of the public
meeting is attached as Appendix B. No comments were made that would effect the
proposed RA for OU2. One written comment and two written requests were received
during the public meeting. The comment and requests are included in Appendix B.
Background on Community Involvement
The public participation requirements of CERCLA Sections 113(k)(2)(B)(i-v) and 117 were
met. HAFB has a Community Relations Plan that is based on community interviews which
was finalized February 1992. The community relations activities include:
a Restoration Advisory Board (RAB) that meets at least quarterly and includes
community representatives from adjacent counties and towns
a mailing list for interested parties in the community
a bi-monthly newsletter called "EnviroNews"
visits to nearby schools to discuss environmental issues
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9/17/96 HILL AIR FORCE BASE. UTAH OPERABLE UNIT 2 RECORD OF DECISION
community involvement in a noise abatement program
semi-annual town council meetings
opportunities for public comment on remedial actions
support for the community for obtaining technical assistance grants (TAGs)
administrative record and information repository
In addition, a public meeting was held on April 28,1993, to explain the risk assessment
process at site-specific risk issues for the communities north of HAFB that are effected by
OUl,OU2,andOU4.
The RI Report (Radian, 1992), RI Addendum (Radian, 1994), Feasibility Study Report
(Radian 1993), FS Addendum (CH2M HILL, 1994), and the Proposed Plan for OU2 (CH2M
HILL 1994) were released to the public, and are available in the Administrative Record
maintained in the Davis County Library and at the Environmental Management Directorate
at HAFB. The notices of availability for these documents were published in the Salt Lake
Tribune. A public comment period was held from May 11,1994, through June 10,1994. In
addition, a public meeting was held on May 25,1994. At this meeting, representatives from
HAFB, EPA, and the State of Utah answered questions about the site and the preferred
alternative. A court reporter prepared a transcript of the meeting. Copies of the transcript
and all written public comments received during the comment period have been placed in
the Administrative Record. In addition, copies of the transcript were sent to all meeting
attendees who requested them. Responses to the comments received during the public
comment period are included in the Responsiveness Summary, which is part of this ROD.
The decision process for this site is based on the Administrative Record.
The HAFB Community Relations Plan and the history of community relations for OU2 are
described in Section 2.4 of the Decision Summary for the ROD.
Summary of Public Comments and Agency Responses
The major community concerns are discussed in the following sections.
Extent and Area of Contamination
Comment
Members of the community were interested in the current location, rate of migration, and
origin of the contaminant plume. A general misunderstanding of what defines an
"operable unit" was apparent from the public comments, as well as the terms "onsite" and
"offsite."
Response
In response to those comments, a review of where all eight OUs are located and the type of
pollutants present were conveyed at the meeting. Many operable units are adjacent to
disposal areas; some are adjacent to places where operations were conducted, such as where
solvents were spilled on the ground. The boundaries of the OU2 area were clarified and a
description of the associated trenches (used for the disposal of solvents), described.
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Definitions of "onsite" and "offsite" were given as "on-the-base," and "everything-outside-
the-base," respectively.
Comment
Numerous questions were raised about the location of the contaminant plume and the
associated hydrogeology. The public expressed concern about the rate of plume migration
and the past, present, and future areas of contamination.
Response
Using visual aids, the plume boundaries and associated pollutant concentrations were
pointed out by Mr. Kirchner (HAFB). In response, scenarios of how the plume may have
been defined 5 years ago were given, as well as a general estimate of the rate of migration of
the contaminant plume: feet per year.
Comment
It was also brought to the panels' attention that the state has piped the groundwater (from
OU4) so that it runs into our agricultural drain across the road. The question was asked "is
the piped groundwater causing additional exposure?"
Response
The investigation team would be interested in knowing where all the groundwater is going
and control of the groundwater flow is paramount. It was requested that the person who
asked the question write his name and address and HAFB will take care of the piping of
groundwater from OU4 across agricultural drains. The HAFB OU4 project manager has
responded to this citizen's request
Hydrogeology and Lithology
Comment
An explanation was requested by the citizens concerning the general hydrogeology of the
OU2 area, the driving force moving the plume, depth of the confining clay layer, and what
effect hill slides may have on the area of concern.
Response
In response, the citizens were informed that OU2 lays on top of the Weber Delta; therefore
in elevation, it is a high point in the vicinity. Precipitation that lands in the vicinity of OU2
infiltrates down through the ground and stops vertically at the impermeable layer, thus
forming the water table. Rain falling on the east side of the runway also creates shallow
groundwater. The impermeable clay layer, which starts 40 to 50 feet below ground surface
(bgs), is several hundred feet thick. This clay layer apparently has held the contamination
(vertical migration) for 20 years.
Comment
A citizen expressed concern about CH2M HILL's December 21,1993, report which stated
that both upper and lower hill sliding has occurred; moreover, inspection on the surface of
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the hill reveals yellow and green sludge, in addition to obnoxious odors. The citizen asked,
what effect does this hill movement and sliding have on the 40- or 50-foot aquifer
underneath; namely, is it possible that the aquifer is leaching some of it (contamination)
above and below the canals (as the result of hill movement).
Although the area in question is outside OU2, Mr. Kirchner did relate to the citizens that
several 100-foot borings were drilled into the clay layers near OU2. Inclinometers were
installed at this site. Mr. Kirchner further explained that inclinometers are used to measure
ground movement.
Types and Concentration of Contaminants
Comment
The amount and extent of groundwater sampling was raised by several members of the
community; specifically, the number of sampling locations located offsite. The number of
sampling events were also of interest to a number of citizens.
Response
In respon3e to these questions, the citizens were informed that there are 19 wells and 10
springs sampled 4 times a year for the OU2 area. The contamination from the Weber-Davis
Canal was also of concern. The citizens were informed the contamination does not go into
the canal. However, the canal (as all concrete canals of that age and construction) leaks.
The leakage has the potential to spread contamination further, but the OU2 contamination
does not impact the canal area. At this time, there are plans to line the Weber-Davis canal.
A description of the pollutant source area (where did the contamination come from?) was
requested by the citizens. The disposal site and type of pollutants were described as
follows: the trenches were unlined, dug into the ground, probably 10 feet deep; the solvents
were collected, after they degreased and cleaned the landing gear parts, in drums and
dumped into these two trendies.
Comment
An inquiry concerning the "wide-scale'' estimate of the spill size was verbally submitted.
Response
In reply, it was stated that nobody kept logs of the amount of solvents dumped into the
trendies 20 years ago, so high and low estimates were calculated taking into consideration:
reuse, evaporation rates, and standard practices at HAFB in the 1960s and 1970s and
calculations based on known occurrence in the subsurface. Currently, the range has been
refined to a value between 30,000 and 100,000 gallons. This estimate is a result of the
amount that has already been pumped from the site. The citizens were informed that the
Risk Assessment is concerned with DNAPL contamination. DNAPLs are very difficult to
extract using currently available technologies and sometimes containment is the only
feasible alternative. However, HAFB will continue to review emerging technologies and
assess their applicability to OU2. In addition, measures to enhance the recovery of DNAPL
will be addressed during remedial design.
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Risk Assessment Methods
Comment
Questions were raised by those in attendance about risk assessment factors, the meaning of
a Hazard Quotient of I, potential pathways, and how the risk numbers are brought about.
Response
It was explained that all pathway exposure times and the type of chemicals are factored into
the risk assessment analyses. The citizens were referred to the Baseline Risk Assessment
document found in the Administrative Record that describes the process and equations for
risk assessment analyses. Also conveyed was that these factors are nationwide standards
approved by the EPA. The Hazard Quotient of 1 is the ratio of the concentrations that an
individual would be exposed to over the number that represents the lowest observed effect
level. Some explanation on "lowest observed first effect" with laboratory animals was
expanded on, as well as adequate protection, balancing criteria, and safety factors.
Potential Health Risks
Comment
Additional questions were raised by the citizens concerning the health, or risk of the
contaminants on vegetation, livestock, and food consumption.
Response
It was stated that since current practice does not include spraying potentially contaminated
groundwater onto the crops, there is no reason for concern. Agricultural, engineering and
scientific communities have studied the entire process and there is no reason for concern.
The type of contamination is not likely to be taken up by vegetation. Because they are
volatile, the pollutants would likely evaporate very quickly if exposed to the atmosphere.
Comment
The other concern about potential health risks included a question about the health risk
now, compared to 5 years ago.
Response
The extent or spread of the contamination is greater now, but the contaminant
concentrations are somewhat less. A definition of non
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9/17/96 HILL AIR FORCE BASE. UTAH OPERABLE UNIT 2 RECORD OF DECISION
Remedial Action Schedule
Comment
A question was asked about the actual time required to implement the RA.
Response
In response, Mr. Kirchner indicated 15 months was allotted by law to implement the RA.
The panel expounded that the construction of the remedial systems would start in the
middle of winter; weather conditions could delay the construction activities and this
remedial cleanup time schedule.
Comment
If HAFB was to close, one citizen inquired, what effect would that have on the RA
schedule?
Response
If a closure occurs, Mr. Kirchner responded, before the property can be turned over to
private industry or the public, each site would have to be remediated before the property
could be purchased. Mr. Elliott interjected that the money associated with this program is
no different than Superfund, which provides money for private section sites. The funding
will continue to be there as long as Congress continues to pay for the program. It was
stated that the clean-up will take 30+ years in the source areas and 15 years for clean-up in
non-source area.
Current Treatabiiity Studies
Comment
One question was raised concerning the amount of, or fraction of, contaminants that will be
removed from the groundwater in the long term.
Response
In response, there was a discussion by panel members about the properties of the
contaminant: TCE. There is a lack of any proven technology to meet the MCL for TCE in
drinking water. The MCL for TCE is 5 parts per billion (ppb). There is no technology that
can remediate DNAPLs in groundwater to that level in a short period of time. The best
knowledge that we have today is being applied to the OU2 site. To date, a total of 30,000
gallons of DNAPL have been pumped out of the OU2 area.
Proposed or Suggested Remediation Technology
Comment
The preferred Source Area Alternative 11, which consisted of a vertical barrier and a surface
cap, was questioned by Louis Cooper of the Davis County Department of Heath. He stated
that the vertical barrier at OU1 was not effective.
SlORME7015B.FaRNAUROORNALDOC 9-6
-------
9/17/96 HILL AIR FORCE BASE. UTAH OPERABLE UNIT 2 RECORD OF DECISION
Response
An explanation of why pollutants migrated out of the OU1 area after placing vertical
barriers followed. Migration of contaminants from OU1 did occur after this type of
technology was used and an inquiry concerning the integrity of the barriers was conducted.
The vertical barrier at OU1 was incorrectly constructed which allowed contaminants to
migrate. The alternatives for installing vertical barriers at OU2 were discussed. The
citizens were informed that the underlying clay layer is 100-feet thick; the vertical barriers
such as Z-channel steel sheet piles could be used and would extend into the underlying
day layer several feet.
PART II-
Comprehensive Response to Specific Legal and Technical
Questions
Specific legal and technical questions raised by the community are described below.
Property Values
Comment
The issue of property devaluation and the adversarial process of being compensated for
land loss was submitted in writing by Brent Poll, who represents the South Weber Landfill
Coalition. Mr. Poll's letter was received on May 25,1994. He expressed concern that the
burden of proof is thrust on those who claim injury (citizens), the HAFB legal office denies
negligence and hides behind the Federal Torts Claims Act. The letter strongly suggests that
the environmental and legal offices of HAFB must find a way to genuinely safeguard its
neighbors against the negligent dumping of toxic wastes on the steep bluffs above South
Weber.
Response
Although no response was presented during the meeting, the response will be presented in
this document. Compensation paid by the Air Force to date has been in the form of lease
payments made for access to property to conduct remedial investigations and to
compensate land owners for losses they suffer as a result of that investigation. The formal
claims process will be handled on a case-by-case basis in regard to compensation for
damages.
Remaining Concerns
Comment
L. Richard Peek requests testing of the springs and groundwater by his and his father's
house, 174 and 120 W. South Weber Drive, phone number is 479-5055.
Response
HAFB responded by directing Mr. Peek's request to the Program Manager at OU4.
SLC\RME70158.FOnNAL\ROORNALDOC 9-7
-------
9/17/96 Hill AIR FORCE BASE. UTAH OPERABLE UNIT 2 RECORD OF DECISION
Comment
Peggy Bon of 2485 East 7800 South, South Weber, Utah 84405 wrote that she would like to
know which OU she and her daughter are located in. Her daughter resides at 1271 East
7600 South, South Weber, Utah.
Response
HAFB responded to Ms. Bon in writing that neither she nor her daughter live within the
boundary of an OU. HAFB stated that both Ms. Bon and her daughter would be placed on
the mailing list so that they will receive information about work being done in the South
Weber area.
SLC\RUE701S8.FORNAL\ROORNALOOC 9-8
-------
Table A-l
Identification of Federal Chemical-Specific ARARs for Operable Unit 2
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/Relevant
and Appropriate
pocumentation
Safe Drinking Water Act -42 USC §300
National Primary Drinking Water
Standards
National Secondary Drinking Water
Standards
Maximum Contaminant Level Goals
40 CFR Part 141
40 CFR Part 143
40 CFR Part 141
Establishes health-based standards for
public water systems and specifies
maximum contaminant levels (MCLs).
Establishes welfare-based standards for
public water systems and specifies
secondary maximum contaminant levels
(SMCLs).
Establishes drinking water quality goals
set at levels of no known or anticipated
adverse health effects, with an adequate
margin of safety.
No/Yes
No/Yes
No/Yes
Clean-up standards will be
based on MCLs since
groundwater is a potential
future source of drinking
water
Clean-up standards may be
based on SMCLs since
groundivater is a potential
future source of drinking
water.
Hie groundwater clean-up
standards may be based on
non-zero MCLCs since
ground water is a potential
future source of drinking
water.
Clean Water Act 33 USC §§ 1251-1376
Water Quality Criteria
40 CFR Part 131
Establishes criteria for water quality based
on toxicity to human health.
No/Yes
The groundwater clean-up
standards will be based on
water quality criteria since
ground water is a potential
water supply if other standards
for drinking water clean up are
not .waihhlc
A-1
-------
Table A-l (Continued)
Standard, Requirement
Criteria, or Limitation
Ambient Water Quality Criteria
Toxic Pollutant Effluent Standards
Citation
40 CFR Part 131
40 CFR Part 129
Description
Establishes criteria for water quality-based
on toxicity to aquatic organisms.
Establishes effluent standards or
prohibition for certain toxic pollutants:
aldrin/ dieldrin, DDT, endrin, toxaphene,
benzidine, and PCDs.
Applicable/Relevant
and Appropriate
No/Yes
No/Yes
Documentation
The grouiulwnter cloan-up
standards will be based on
ambient water quality criteria if
no other drinking water
standards or water quality
criteria are available.
Aldrin, dieldrin and endrin
have been detected in low
concentrations at OU2.
Solid Waste Disposal Act - 42 USC §§ 6901-6987
Criteria for the Identification and
Listing of Hazardous Waste
Requirements for Releases from
Solid Waste Management Units
Land Disposal Restrictions
40 CFR Part 261
40 CFR Part 264,
Subpart F
40 CFR Part 268
Establishes solid wastes which are subject
to regulation as hazardous waste under 40
CFR Parts 124, 262-265, 268, and 270.
Establishes maximum concentrations for
hazardous constituents in the ground water
Establishes maximum concentrations for
hazardous constituents prior to land
disposal.
Yes/~
No/Yes
Yes/-
Wastes generated during the
remediation phase have been
determined to contain RCRA
hazardous constituents and
will be subject to identification
and listing as hazardous
wastes.
The groundwater clean-up
standards may be based on
these maximum concentrations
if they are more stringent than
MCLs or non-zero MCLGs, or
if no standards exist. *
Hazardous wastes generated
during the remediation phase
will be subject to land disposal
restrictions and ni.iy be
required to meet DDAT
technologies and /or
constituent concentrations
A2
-------
Table A-l (Continued)
- . - -^^^^ - '-
Standard, Requirement,
Criteria, or Limitation
Nation.il Ambient Air Quality
Stand .iMs
National Emissions Standards for
Hazardous Air Pollutants
(NESHAP)
New Source Performance Standards
Citation
40CFRPart50
40CFRPart61
40CFRPart60
Description
Establishes primary and secondary
standards for six pollutants: PMllt/ SO,,
CO, ozone, NO,, and load.
Establishes regulatory standards for
specific air pollutants: arsenic, asbestos,
benzene, beryllium, mercury,
radionuclides, and vinyl chloride.
Establishes performance standards for
certain types of new stationary sources.
Applicable/Relevant
and Appropriate
Yes/~
No/Yes
No/No
Documentation
Emissions from the
remediation process will be
subject to the National Ambient
Air Quality Standards unless
state standards are more
stringent.
Beryllium in source area soils
has been identified as a
chemical of concern.
No new major sources (for
example incinerators) are
proposed as part of remedial
activities.
A3
-------
Table A-2
Identification of State Chemical-Specific ARARs for Operable Unit 2
Standard, Requirement,
Criteria, or Limitation
Citation
«r
Description
Applicable/Relevant
and Appropriate
Documentation
Utah Safe Drinking Water Act - Title 19 UCA Chapter 4
Utah Primary Drinking Water
Standards
Utah Secondary Drinking Water
Standards
R39-103-1 UAC
R309-103-2 UAC
Establishes maximum contaminant levels
for inorganic and organic chemicals as
primary drinking water standards.
Establishes maximum contaminant levels
for inorganic and organic chemicals as
secondary drinking water standards.
No /Yes
No/Yes
Requirements are relevant and
appropriate for OU2. Some
MCLs established for
contaminants are not Federally
regulated (e.g., total dissolved
solids).
Requirements are relevant and
appropriate for OU2.
Utah Solid and Hazardous Waste Act - Title 19 UCA Chapter 6 Part 1
Land Disposal Restrictions
Criteria for the Identification and
Listing of Hazardous Waste
R315-13 UAC
R315-2-1 UAC
Outlines land disposal restrictions for
hazardous waste. Utah incorporates
Federal LDRs by reference.
Establishes solid wastes that are regulated
as hazardous wastes under the Utah Solid
and Hazardous Waste Act. Definition of
hazardous waste mirrors federal
definition.
Yes/-
Yes/-
Hazardous wastes generated
during remediation will be
subject to land disposal
restrictions and may be
required to meet BDAT
technologies and /or
constituent concent ral ions.
Wastes generated during the
remediation phase have been
determined to contain
hazardous constituents and
will be subject to identification
and listing as hazardous
wastes.
A-4
-------
Table A-2 (Continued)
Standard, Requirement
Criteria, or Limitation
Ground Water Protection Standards
for Owners and Operators of
Hazardous Waste Treatment,
Storage, and Disposal Facilities
Citation
R315-8-6.5 UAC
Description
Establishes maximum concentrations for
hazardous constituents in ground water.
Applicable/Relevant
and Appropriate
No/Yes
pocumentation
The ground water clean-up
standards may be based on
these maximum concentrations
if they are more stringent than
MCLs or non-zero MCLGs, or
if no standards exist.
Utah Water Quality Act - Title 19 UCA Chapter 5
Ground Water Quality Protection
Rule
Underground Injection Control
(U1C) Standards
R317-6 UAC
R317-7 UAC
Establishes ground water quality
standards for different aquifer classes.
Establishes general requirements,
definitions, permitting procedures, and
opiT.il inj; standard. UIC standards adopt
by rHrrfiu-r the tfdcral UIC regulations
with the .exception of a 2-mile radius from
the boreliole instead of a one quarter-mile
radius from the borehole to an
underground source of drinking water.
(See Documentation
column for explanation)
Yes/-
The Utah Ground Water
Quality Protection Rule
establishes numerical clean up
levels and other performance
standards for contaminated
ground water. Although no 1
determination has been made 1
concerning whether this Rule is
an applicable or relevant and
appropriate standard at OU2,
the standards required by the
Ground Water Quality
Protection Rule will be met by
complying with drinking water
MCLs.
Hie UIC regulations would be
applicable for remedial
activities that involve ni|«vhon
of surfactants, strain injection,
or soil flooding. St.ite
counterpart to 40 CPR Paris
144-147.
A-5
-------
Table A-2 (Continued)
Standard, Requirement,
Criteria, or Limitation
Water Quality Standards
Citation
R317-2UAC
Description
Establishes standards for the quality of
surface waters in the State.
Applicable/Relevant
and Appropriate
No/Yes
Documentation
These rules are specific to Utah,
ajthough they are derived, in part,
from federal criteria. May be
relevant and appropriate since
ground water is a potential water
supply if other standards are not
available.
- Utah Air Conservation Act -Title 19 UCA Chapter 2
State Adoption of the National
Ambient Air Quality Standards
(NAAQSs)
Standards for Visible Emissions,
PM10 Attainment Areas, Emissions
from Internal Combustion Engines,
and New Source Performance
Standards
National Emission Standards for
Hazardous Air Pollutants
(NESMAPs) as Implemented by
Utah
Fugitive Dust Emission Standards
Ozone Non Attainment Area
Standards for Davis County, Utah
R307-1-3 UAC
R307-M UAC
R307-10 UAC
R307-12UAC
R307-14 UAC
Specifies NAAQSs for PM,., SO,, CO,
ozone, NO,, and lead. State adoption of
Federal NAAQS and Best Available
Control Technology (DACT).
Establishes air quality standards for visible
emissions, PMIO attainment areas,
emissions from internal combustion
engines, and new source performance
standards (NSPS).
Specifies emission standards for hazardous
air pollutants from various source
categories
Establishes fugitive dust emission
standards."
Establishes area standards for sources th.1t
emit air pollutants that are precursors for
the formation of ozone.
Yes/NA
Yes/NA
Yes/NA
Yes/NA
Yes/NA
Emissions from remedial activities
cannot result in exceedance of
NAAQS.
This rule is applicable for emissions
generated from remedial activities.
Davis County is a non attainment
area for PMlu. Remedial system that
require electrical backup systems
powered by diesel internal
combustion engines must meet
emission standards.
Emissions from remediation systems
subject to NESHAPs.
Fugitive dust emissions generated
during remedial action construction
activities will he subject to these
standards.
Emissions from the remediation
process will be subject to emission
standards for area sources.
A6
-------
Table A-3
Identification of Federal Location-Specific ARARs for Operable Unit 2
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/Relevant
and Appropriate
Documentation
Solid Waste Disposal Act - 42 VSC §§ 6902-6987
Location Standards for Hazardous
Waste Management Units
40 CFR§ 264.18
Establishes site characteristics which are
unsuitable for location of hazardous waste
management units.
Yes/~
Standard is an ARAR for
hazardous waste remediation
units at OIJ2 Remediation
units will not be located on a
fault or in a 100-year
flood plain.
A-7
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Table A-4
Identification of State Location-Specific ARARs for Operable Unit 2
Standard, Requirement
Criteria, or Limitation
Citation
Description
Applicable/Relevant
and Appropriate
Documentation
Utah Solid and Hazardous Waste Act - Title 19 UCA Chapter 6 Part 1
Location Standards for Hazardous
Waste Management Units
R315-8-2.9 UAC
Establishes site characteristics which are
unsuitable for location of hazardous waste
management units.
Yes/-
Standard is an ARAR for
hazardous waste remediation
units at OU2. Remediation units
will not be located on a fault or
in a 100-year floodplain.
A8
-------
Table A-5
Identification of Federal Action-Specific ARARs for Operable Unit 2
Standard, Requirement,
Criteria, or Limitation
Citation
Description
Applicable/Relevant
and Appropriate
Documentation
Clean Water Act - 33 USC §§ 1251-1376
National Pollutant Discharge
Elimination System Requirements
National Pretreatment Standards
Underground Injection Control
Program under the Safe Drinking
Water Act
40 CFR Part 122
40 CFR Part 403
40 CFR Parts 144-
147
Establishes requirements for permits to
authorize (he point source discharge of
pollutants into waters of the Unites States.
Also, regulates discharges of storm water.
Establishes standards for controlling
pollutants which pass through or interfere
with treatment processes in publicly
owned treatment works or which may
contaminate sewage sludge.
Establishes regulations for the subsurface
emplacement of fluids through an injection
well
Yes/-
Yes/-
Yes/-
Discharge of treated surface water
into waters of the United St.ites and
stonnwater discharges may be
associated with the remediation
strategy.
Remediation strategy will include
pretreatment at the existing HAFD
industrial wastewater treatment
plant prior to treatment in puhlii ly
owned treatment works.
The UIC regulations would be
applicable for remedial activities that
involve injection of surfactants,
steam injection, or soil flooding.
Solid Waste Disposal Act - 42 USC §§ 6901-6987
Criteria for Classification of Solid
Waste Disposal Facilities and
Practices
40 CFR Part 257
Establishes criteria for use in determining
when solid waste disposal facilities pose a
reasonable probability of adverse effects on
health or the environment.
Yes/-
Land disposal of solid nonhazardous
waste may be part of the
remediation strategy.
A-9
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Table A-5 (Continued)
Standard, Requirement
Criteria, or Limitation
Criteria for Municipal Solul Waste
Landfills
Standards Applicable to Generators
of Hazardous Waste
Standards Applicable to
Transporters of Hazardous Waste
General Facility Standards
Security Standards for TSDFs
General Inspection Standards
Personnel Training Standards
Citation
40 CFR Part 258
40 CFR Part 262
40 CFR Part 263
40 CFR Part 264,
Subpart D
40 CFR Part 264 14
40 CFR Part 264.15
40 CFR Part 264.16
Description
Establishes minimum national criteria
under RCRA for all municipal solid waste
landfill units.
Establishes requirements for generators of
hazardous waste.
Establishes requirements for transporters
of hazardous waste.
Establishes general facility management
standards for hazardous waste treatment,
storage, and /or disposal facilities.
Establishes security requirements to
prevent unauthorized access to TSDFs.
Establishes inspection standards for
TSDFs.
Establishes training requirements for
personnel that manage TSDFs.
Applicable/Relevant
and Appropriate
Yes/-
Yes/--
Yes/--
Yes/--
Yes/--
Yes/~
Yes/-
Documentation
Site does no! include any municipal
solid waste landfills. Would be
applicable for disposal of non-
hazardous solid waste, (/.round
water monitoring requirements
could become relevant and
appropriate for a no action
alternative.
Remediation strategy includes
generation of hazardous waste.
Remediation strategy may include
the transportation of hazardous
waste (e.g., soil).
Certain general facility standards
are applicable and facility
management plans may be
developed, as needt»d, to
implement other 40 CPR Part 264
requirements.
Remedial activities will require
security measures to prevent access
to TSDFs by unauthorized persons.
Remedial activities that involve
onsite TSDFs will require the
preparation and implementation of
an inspection plan.
Remedial activities that involve
msile TSDFs will require the
^reparation and implementation of
a personnel training program.
A-10
-------
Table A-5 (Continued)
Standard, Requirement,
Criteria, or Limitation
Gener.il Requirements for Ignitahle,
Reactive, or Incompatible Wastes
Construction Quality Assurance
Standards of Preparedness and
Prevention
Contingency Plan and Emergency
Procedures
Manifest System, Record keeping,
and Reporting Requirements
Requirements for Releases Prom
Solid VV.iste Management Units
Citation
40 CFR Part 264.17
40 CFR Part 264.19
40 CFR Part 264,
Subpart C
40 CFR Part 264,
Subpart D
40 CFR Part 264,
Subpart E
40 CFR Part 264,
Subpart F
Description
Establishes requirements to prevent
storage, treatment, and management of
incompatible hazardous wastes.
Establishes the requirement to prepare and
implement a construction quality
assurance plan.
Establishes requirements for preparedness
and prevention at hazardous waste
treatment, storage, and/or disposal
facilities.
Establishes requirements for a contingency
plan and emergency procedures at
hazardous waste treatment, storage,
and /or disposal facilities.
Establishes requirements for the manifest
system as well as recordkeeping and
reporting at hazardous waste treatment,
storage, and /or disposal facilities.
slahlishes requirements for detection and
containment of releases from waste
management units at hazardous waste
treatment storage, and/or disposal
facilities.
Applicable/Relevant
and Appropriate
Yes/-
Yes/-
Yes/-
Yes/-
Yes/--
Yes/--
Documentation
Procedures are applicable to
prevent storage, management, and
treatment of incompatible
hazardous waste that may be
generated during remedial
activities.
Remedial activities will involve
construction activities. Preparation
and implementation of a
construction quality assurance plan
is applicable. 1
Preparedness and prevention 1
measures may be developed, as
needed, to implement other 40 CFR
Part 264 requirements.
A contingency plan and emergency
procedures may be developed, as
needed, to implement other 40 CFR
Part 264 requirements.
Requirements for the manifest
system, recordkeeping, and
reporting will be developed, .is
needed.
Solid waste management units
associated with the remediation
strategy will have secondary
containment to preclude releases. If
the selected alternative involves
capping/ containment and /or
continued ground water 1
monitoring, ground water I
monitoring requirements will be 1
applicable. 1
A-11
-------
Table A-5 (Continued)
1
Standard, Requirement,
Criteria, or Limitation
Closure and Post-Closure Standards
Standards for the Use and
Management of Containers
Standards for Tank Systems
Standards for Landfills
Standards for Incinerators
Corrective Action Management Unit
(CAMU)
Citation
40 CFR Part 264,
Subpart G
40 CFR Part 264,
Sub part I
40 CFR Part 264,
Subpart j
40 CFR Part 264,
Stibpart N
40 CFR Part 264,
Subpart O
40 CFR Part 264
Subpart S
Description
Establishes general standards for closure
and, if required, post-closure at hazardous
waste treatment, storage, and /or disposal
facilities.
Established design and operational
standards for the use and management of
containers storing hazardous waste at
TSDFs.
Establishes design and operational
requirements for the storage and /or
treatment of hazardous wastes in tanks at
hazardous waste treatment, storage,
and /or disposal facilities.
Establishes design and operational
requirements for hazardous waste landfills.
Establishes design and operational require-
ments for hazardous waste incinerators.
Establishes requirements for designation of
a CAMU and defines management
> radices.
Applicable/Relevant
and Appropriate
Yes/Yes
Yi's/«
Yes/--
No/Yes
No/Yes
Yes/-
Documentation
Closure and, if required, post-
closure will be needed for any
hazardous waste management units.
Use of containers storing hazardous
waste will not be part of the
remediation strategy. 1 lowcvor, all
temporary storage and management
of containers containing hazardous
waste will be in accordance with the
requirements of this subpart.
Tank systems for the storage and /or
treatment of hazardous waste will be
in accordance with the requirements
of this subpart.
Standards for a surface cap will be
relevant and appropriate. The
standards for closure and post-
closure are relevant and appropriate.
Remediation strategy does not
include onsite operation ot an
incinerator. Incinerator standards
may be relevant and appropriate tor
low temperature thermal treatment
alternative.
Applicable to remedial activities in
which treated soil is returned to the
site of removal. Allows exemption
o LDRs if clean-up goals are
achieved.
A 12
-------
Table A-5 (Continued)
Standard, Requirement
Criteria, or Limitation
Air Emissions Standards
Standards for Thermal Treatment
Standards for Chemical, Physical,
and Biological Treatment
Land Disposal Restrictions
Citation
40 CFR Part 264,
Subparts A A and DB
40 CFR Part 265
Suhpart P
40 CFR Part 265
Suhpart Q
40 CFR Part 268
Description
Establishes monitoring and recordkeeping
requirements for process vents and equip-
ment leaks.
Establishes standards for other thermal
treatment of hazardous wastes.
Establishes standards for chemical,
physical, or biological treatment of
hazardous wastes that do not occur in
tanks, surface impoundments, or waste
piles.
Establishes hazardous wastes that are
restricted from land disposal and
describes those circumstances where
treated waste may be land disposed.
Applicable/Relevant
and Appropriate
Yes/-
To- He-Considered
To-Be-Considered
Yes/-
Documentation
Equipment meeting the applicability
requirements will be monitored in
accordance with the requirements of
these subparts.
If other thermal treatment is
performed as part of the
remediation, this unit will he
designed and operated in
accordance with the requirements of
Ihissubparl.
This regulation is to be considered
for remedial activities including soil
vapor extraction (SVE) and the
Source Recovery System.
Hazardous wastes generated during
remediation will be managed in
accordance with the requirements as
specified in this rule.
Clean Air Act - 42 USC § 7401
Standards of Performance for
Incinerators
Standards of Performance for
Volatile Organic Liquid Storage
Vessels (Post 7/23/84)
40 CFR Part 60,
Suhpart E
40 CFR Part 60,
Suhpart K»
Establishes standards of performance for
solid waste incinerators.
Establishes standards of performance for
storage tanks containing volatile organic
liquids.
Yes/-
Yes/No
Hazardous waste that is treated by
low temperature thermal treatment
will be in accordance with the
requirements of this subpart.
Hazardous wastes that are defined
as volatile organic liquids will be
stored in accordance with the
requirements of this subpart.
A-13
-------
Table A-5 (Continued)
Standard, Requirement/
Criteria, or Limitation
Citation
Description
Applicable/Relevant
and Appropriate
Documentation
Occupational Safety and Health Act - 29 USC §§ 651-678
Worker Safety Standards
29 CFR Part 1910
Establishes standards for worker safety at
hazardous waste facilities.
Yes/-
Worker safety requirements will be
in accordance with the requirements
of this part.
Hazardous Materials TranspoHation Act - 49 USC §§ 1801-1813
Hazardous Materials Transportation
Requirements
49 CFR Parts 107
and 171-177
Establishes requirements for
transportation of hazardous materials.
Yes/-
Transportation of hazardous
materials off-site will be in
accordance with the requirements of
these parts.
A-14
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Table A-6
Identification of State Action-Specific ARARs for Operable Unit 2
Standard, Requirement
Criteria, or Limitation
Citation
Pescription
Applicable/Relevant
and Appropriate
Pocumentation
UCA 73-3-25
Well Drilling Standards
R655-4 UAC
Establishes standards for drilling and
abandonment of wells
Yes/-
The selected remedy includes ground
water monitoring and extraction wells.
£. Utah Occupational Safety and Health Act - Title 35, UCA Chapter 9
Worker Safety Standards
1
R574 UAC
Establishes occupational safety and health
standards. Rules mirror Federal OS HA
regulations.
Yes/»
All remediation standards will require
worker safety procedures and practices.
Utah Air Conservation Act - Title 19 UCA Chapter 2
Definitions and General Requirements
for Air Conservation
Standards for the Control of
Installations
National Emission Standards for
1 lazardoits Air Pollutants (NI-SH APs)
R307-1-1 and
R307-1-2 UAC
R307-1-3 UAC
R307-10 UAC
Outlines general requirements and
provides definitions for Utah Air
Conservation rules.
Establishes notification requirements,
details operating limitations, requires
implementation of Best Available Control
Technology (BACT), and specifies criteria
for NAAQS violations and Prevention of
Significant Deterioration (PSD) review.
Establishes NESHAPs for specific source
categories.
Yes/~
Yes/~
Yes/-
General requirements and definitions will
be applicable for remediation strategies
which include pollutant emissions.
Notification and reviews for NAAQS
violations and PSD will be required for
remediation strategies which include
pollutant emissions. NAAQS violations
and PSD review are not expected due to
the low emission rates.
Remediation systems that generate 1 1 AP
emissions may be subject to these
regulations.
A 15
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Table A-6 (Continued)
Standard, Requirement,
Criteria, or Limitation
Fugitive Dust Emissions
Continuous Emission Monitoring
System Requirements
Ozone Attainment Area Standards for
Davis County, Utah
Citation
R307-12 UAC
R307-13UAC
R307-14 UAC
Description
Establishes limits of the amount of
fugitive dust emissions.
Establishes continuous emission
monitoring system requirements for those
air emission sources subject to this rule.
Establishes limits on emission that are
precursors for the formation of ozone in
Davis County, Utah. Davis County is a
non attainment area for ozone and these
regulations have been issued as part of
the State Implementation Plan.
Applicable/Relevant
and Appropriate
Yes/-
Yes/-
Yes/--
Documentation
Remedial action construction activities
may result in the generation of fugitive
dust emissions. These emissions are
regulated by this rule.
Remediation systems that have air
emissions may be required to install
continuous monitoring systems in
accordance with this rule.
Remediation systems may have emissions
that are subject to this regulation.
Utah Solid and Hazardous Waste Act - Title 19 UCA Chapter 6 Part 1
Definitions and General Requirements
for Solid and Hazardous Waste
Hazardous Waste Manifest
Requirements
Hazardous Waste Generator
Requirements
Hazardous Waste Transporter
Requirements
R315-1 and
R315-2 UAC
R3I5-4 UAC
R315-5 UAC
R315-6 UAC
Outlines general requirements and
provides definitions for Utah Solid and
Hazardous Waste Regulations.
Details requirements for manifesting
shipments of hazardous waste in the
State.
Outlines requirements for generators of
hazardous waste.
Outlines requirements for the
transportation of hazardous waste.
Yes/-
Yes/~
Yes/-
Yes/-
General requirements and definitions will
be applicable for the management of solid
and /or hazardous waste.
All offsite shipments of hazardous waste
will require manifests meeting State
requirements.
Generator requirements will be applicable
for all hazardous waste generated during
remediation.
Requirements will be applicable to
remediation strategies which include
offsite transportation of hazardous waste.
A-16
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Table A-6 (Continued)
Standard, Requirement,
Criteria, or Limitation
St.init.irds for 11uTin.il Treatment
Standards for Chemical, Physical, and
Biological Treatment
Security Standards for Hazardous
Waste Treatment, Storage, and
Disposal Facilities (TSDFs)
General Inspection Requirements
Personnel Training
General Requirements for Ignitable,
Reactive, or Incompatible Waste
Citation
R315-7 23 UAC
R315-7-24 UAC
R315-8-2.5 UAC
R315-8-2.6 UAC
R315-8-2.7UAC
R315-8-2.8 UAC
Description
Establishes standards for other thermal
treatment of hazardous wastes.
Establishes standards for chemical,
physical, or biological treatment of
hazardous wastes that do not occur in
tanks, surface impoundments, or waste
piles.
Outlines security requirements at active
portions of a TSDF.
Outlines inspection requirements at
TSDFs.
Describes training requirements for TSDF
staff.
Outlines requirements to prevent
accidental ignition or reaction of ignitable
>r reactive wastes.
Applicable/Relevant
and Appropriate
To-Be-Considered
To-Be-Considered
Yes/-
Yes/-
Yes/-
Yes/-
Documentation
If other therm.il treatment is performed as
part of the remediation, this unit will be
designed and operated n accordance with
the requirements of this subpart.
This regulation is to be considered for
remedial activities including soil vapor
extraction (SVE) and the Source Recovery
System.
Establishes minimum requirements to
prevent unauthorized access by persons or
livestock into an active portion of a TSDF
and describes other security procedures.
Establishes the requirements that
owners /operators of a TSDF inspect their
facilities to minimize potential unplanned
releases of hazardous waste constituents to
the environment. This rule requires that an
inspection schedule be developed.
Establishes facility personnel training
requirements
Establishes requirements for TSDFs to
prevent storage, treatment, or disposal of
incompatible hazardous waste that could
result in accidental ignition or reaction of
\vaste. Requires the TSDF to document
compliance with this regulation.
A-17
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Table A-6 (Continued)
Standard, Requirement,
Criteria, or Limitation
Construction Quality Assurance
Program
Preparedness and Prevention
i
i
Contingency Plan and Emergency
Procedures
Manifest System, Recordkeeping, and
Reporting
Groundwater Protection
Closure and Post Closure
Standards for Use and Management of
Containers
Citation
R315-8-2.IOUAC
R315-8-3 UAC
R31 5-8-4 UAC
R31 5-8-5 UAC
R315-8-6 UAC
R3I5-8-7 UAC
R315-8-9 UAC
Description
Establishes the requirement for a
Construction Quality Assurance Program
for all landfill units including liners and
final cover systems.
Outlines facility design requirements,
required equipment, testing and
maintenance of equipment,
communication and alarm systems, aisle
space requirements, and arrangements
with local authorities in the event of an
accidental release.
Outlines the requirements for
development of contingency plans and
establishment of emergency procedures.
Outlines procedures for manifesting,
record keeping, and reporting at TSDFs.
Describes groundwater monitoring
requirements for TSDFs.
Establishes closure and post-closure
performance standards and plan
requirements for TSDFs
Establishes standards for use and
management of containers
Applicable/Relevant
and Appropriate
Yes/»
Yes/~
Yes/~
Yes/--
Yes/-
Yes/~
Yes/~
Documentation
Remedial construction activities will
require the preparation and
implementation of a Construction Quality
Assurance Program.
This rule will be applicable as hazardous
waste storage and treatment will be part of
remedial activities.
This rule is applicable to remedial
activities.
This rule is applicable as hazardous waste
will lie generated during remedial
activities. State counterpart of 40 CFR Part
264 Subpart E.
Applicable to remedial activities involving
storage, treatment, and disposal at on-site
facilities. State counterpart of 40 CFR Part
264 Subpart F.
Applicable to remedial activities that
involve on-site TSDFs. State counterpart to
40 CFR Part 264 Subpart G.
Applicable to use and management of
containers holding hazardous waste. State
counterpart of 40 CFR Part 264 Subpart 1.
A-18
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Table A-6 (Continued)
Standard, Requirement,
Criteria, or Limitation
Standards for Use and Management of
Tanks
Landfills
Incinerators
Air Emissions Standards for Process
Vents
Air Emission Standards for Equipment
.oaks
Corrective Action Management Unit
(CAM LI)
Chemical, Physical, and Biological
Treatment
Citation
R315-8-10UAC
R315-H-14 UAC
R315-8-15 UAC
R315-8-17 UAC
R315-8-18 UAC
R315-8-21 UAC
R315-7-24 UAC
Description
Establishes standards for use and
management of tanks containing
hazardous waste.
Establishes design, operation, and
management requirements for disposal of
hazardous materials in landfills.
Establishes design, operation, and
management requirements for
incinerators.
This regulation incorporates the
requirements as found in 40 CFR Sub part
AA Sections 264.1030 through 264.1036,
1990 ed.
This regulation incorporates the
requirements as found in 40 CFR Sub part
DU Sections 264.1050 through 264.1065,
1990 ed.,
Establishes requirements for designation
of A CAMU and defines management
iraclices.
Establishes design, operation, and
maintenance requirements for chemical,
physical, and biological treatment units.
Applicable/Relevant
and Appropriate
Yes/--
No/Yus
No/Yes
Yes/-
Yes/-
Yes/-
To- De-Considered
Documentation
This regulation will be applicable if
remediation system require the use of tanks
to treat or store hazardous waste. Slate
counterpart of 40 CFR Part 264 Subpart J
Applicable to remedial activities that will
involve capping of portions of the source
area. Slate counterpart of 40 CFR Part 264
Subpart N.
Remediation strategy does not include
onsite operation of an incinerator.
Incinerator standards may be relevant and
appropriate if low temperature thermal
treatment of excavated soil is employed.
State counterpart of 40 CFR Part 264
Subpart O.
This regulation is applicable for Source 1
Recovery System and other treatment 1
process that are part of remedial activities. 1
This regulation is applicable for Source
Recovery System and other treatment
process that are part of remedial activities.
Applicable to remedial activities in which
treated soil is returned to the site of
removal. Allows exemption to LDRs if
clean-up goals are achieved. State
counterpart of 40 CFR Part 2
-------
Table A-6 (Continued)
Standard, Requirement,
Criteria, or Limitation
Land Disposal Restrictions
Clean-up Action and Risk- Based
Closure Standards
Underground Injection Control
Standards
Corrective Action Clean-up Policy (or
CERCLA and Underground Storage
Tank (UST) Sites
Citation
R315-13UAC
R315-101 UAC
R317-7UAC
R311-211UAC
Description
Outlines land disposal restrictions for
hazardous waste. Utah incorporates
Federal LDRs by reference
This rule establishes risk-based closure and
corrective action requirements.
Establishes regulations for the subsurface
implement of fluids through an injection
well
This rule addresses clean-up requirements
at CERCLA and UST sites.
Applicable/Relevant
and Appropriate
Yes/~
Yes/»
Yes/»
Yes/~
Documentation
This regulation is applicable as hazardous
waste will be generated during remediation
activities
This rule is applicable for remedial activities
including site management, corrective
action, and closure.
The UIC regulations would be applicable for
remedial activities that involve injection of
surfactants, steam injection, or soil flooding.
State counterpart to 40 CFR Parts 144-147.
Remediation strategy must achieve
compliance with the policy. The policy sets
forth criteria for establishing clean-up
standards and requires source control or
removal, and prevention of further
degradation.
IUtah Water Quality Act - Title 19 UCA Chapter 5
Definitions and General Requirements
Design Requirements for Waste water
Collection. Treatment, and Disposal
Systems
Ground Water Quality Protection Rule
R317-1 UAC
R317-3UAC
R317-6UAC
Details definitions and general
requirements for water quality in Utah.
Outlines design requirements for the
collection, treatment, and disposal of
domestic waslewater.
Details standards, classes, protection
levels, and implementation criteria for
ground water protection. Also, outlines
certain activities permitted by rule.
Yes/~
No/Yes
*
(See Documentation
Column for explanation)
General requirements and definitions will be
applicable for remediation strategies
including point source discharges.
Treatment of domestic wastewater will not
be part of remediation strategies. 1 lydraulic
design requirements may be relevant and
appropriate.
'The Utah Ground Water Quality 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 OU2, the
remedy \vill meet the action-specific
requirements of the rule.
A 20
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Table A-6 (Continued)
Standard, Requirement,
Criteria, or Limitation
Underground Injection Control
Standards
Utah Pollutant Discharge Elimination
System Requirements
Citation
R317-7 UAC
R317-8 UAC
Description
Establishes general requirements,
definitions, permitting procedures, and
operating standards. UIC standards adopt
by reference the federal UIC regulations
with the exception of a two-mile radius
from the borehole instead of a one-quarter-
mile radius from the borehole to an
underground source of drinking water.
Establishes general requirements,
definitions, permitting procedures, and
criteria /standards for technology-based
treatment for point source discharges of
wastewater. Also establishes p retreat men t
standards for discharge to a POTW.
Applicable/Relevant
and Appropriate
Yes/-
Yes/--
Documentation
If soil flushing involves injection of treated
ground water, UIC standards would be
applicable
If selected alternative involves a point
source discharge of wastewater, UPDES
requirements would be applicable.
Pretrealment standards would be applicable
if selected alternative involved discharge to
a POTW.
A 21
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OUR FILE NO.
44048-145
Copy \
PUBLIC MEETING
OPERABLE UNIT 2 PROPOSED PLAN
SOUTH WEBER ELEMENTARY SCHOOL
7:00 P.M.
MAY 25, 1994
Rsccr.sd cy SHIRLVN SHARPS. CSR. RPR. CM
Utah C3R License 57
lU(f 5l$C(!(l?6$ Certified Shorthand Reporters
One Utah Center. Suite 900
201 South Main Street
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Public Meeting of Residents of South Weber
regarding Operable Unit 2, held on Wednesday,
May 25r 1994, 7:00 p.m., at South Weber
Elementary School, South Weber, Utah.
*****
IN ATTENDANCE:
Colonel Steven Emory
Ms. Gwen Brewer
Mr. Rob Stites
Mr. Bob Elliott
Mr. Howard Saxion
Mr. Marc Aurelius
Ms. Diane Simmons
Mr. John Peterson
Mr. Chris Mikell
Mr. Chuck Neeley
Mr. Steve Godard
Mr. L. Richard Peek
Mr. Steve Brown
Other members of the public
KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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PROCEEDINGS
* * * ** *
MS. BREWER: I think we'll get started. You can
4 all hear me can't you? My name is Gwen Brewer, Coordinator
5 for Environmental Public Affairs at Hill Air Force Base. We
6|| welcome all of you to the public meeting this evening.
During the meeting, we will be discussing some
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things that to some of you may sound technical. If they go
over your heads, let us know. We try to adjust our language
so that everybody can understand, but sometimes I don't
understand. Don't be afraid to say anything.
This meeting is for the record. You will notice
that we do have a recorder. She will take down all of the
proceedings for this meeting. That will be entered into our
Administrative Record. Any comments or questions you have
this evening will be addressed in a follow-up'document.
Once an alternative is decided upon, based on your input,
we'll do a follow-up document and then you will know what
alternative was selected.
We have a few rules this evening. Because of the
way it is structured, we ask you to hold your questions or
comments until, after the presentations. In all of your
packets, there is a sheet that you can write the comments
on. You can either ask them this evening, or if you are
bashful and don't want to ask anything this evening, you can
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KINGSBt*Y^*ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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l|| leave it at the table in the back or you can mail it to us.
Sometimes you don't think of anything until the meeting is
over. It isn't over until the llth of June. We'll be
19:09:00 4 taking comments until then. So, if you think of something
5 afterwards, please let us know by a phone call or even send
6 in that comment sheet.
The most important part of this meeting is to get
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feedback from you as to what method or how you would like
the situation handled here. We'll give you several
alternatives. We'll tell you the one that we prefer. We'll
also tell you why it is the one that we prefer.
We have several things on the agenda this
evening. First, we're going to start with Colonel Emory who
will go through some other things with you.
COLONEL EMORY: First of all, I would like to
introduce a few people. Myself, for starters.- I'm the Air
Base Group Commander at Hill Air Force Base. That is kind
of like mayor of a small town we have out there.
I might as well introduce Pam Jones back there,
Councilwoman in South Weber, my counterpart in South Weber.
We have a lot of people that are working on this
project with us. From the Environmental Protection Agency,
we have Rob Stites. John Peterson from the Utah Department
of Air Quality. Hal Dunning, an expert with the EPA that
is part of the Gwen Brewer and Bob Elliot combination where
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we translate all of the vernacular that we have got and tell
you what we're doing and why we are how we are going to
get our sites cleaned up, what it looks liker what sort of a
threat it is to you.
That is part of our purpose here this evening, to
give you the current status of what we've got out there, how
it got there, what the potential threat is to you, the
community, and then what we're doing, what we're planning to
do to clean that up, all of the official policy and
procedures that go along with how we got there, show you
some of the logic that we used that you helped us with,
by the way some of the logic in determining the options
that we kind of zeroed in, on and our primary plan that
we'll recommend for cleaning up the problem.
This is a formal meeting, an official part of the
process. You know, in the past, we came and talked to you
to get interaction with you to see what is going on. Parr
of the unofficial is to keep you informed. This is for the
record, as Gwen explained.
Bob Elliot runs the whole remediation program, if
you would, for Hill Air Force Base. Operable Unit 2 and
South Weber is one part of that operation. Our engineer for
the site, Kyle Kirchner, will be the one that will spend
most of the evening with you, speaking with you about what
the recommendations are for the site.
KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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ill Let me echo what Gwen talked to you about; that
2|| is, our primary purpose for laying this out is for all our
experts out there that are in this business to review our
process, get a head nod, make sure we have all our ducks in
a row as far as pressing on further in this process, and to
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get your inputs on any sort of questions that you have,
recommendations that you've got, problems, all that sort of
business, so that we can make sure we have got the community
totally wrapped up in our game plan.
Without further ado, I think, Bob, you are kicking
it off next.
MR. ELLIOT: I am Bob Elliot. Can everyone hear
13| me okay? I want to take a couple of minutes to explain the
II »*"*«
19:13:00 14 process. It looks like we will have enough light. We were
15 a little concerned about that.
16 I wanted to explain the Superfund process, which
17 is the process under which this particular project is being
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worked on. This process is called the or is regulated
under the Comprehensive Environmental Response Compensation
Liability Act. That is a huge acronym for Superfund, and
this is the process.
As many of you know, the process is a very long
process. There has been a lot of frustration across the
country about the length of this process and the amount of
review. Let me just point out some of the key milestones
KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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here.
Initially/ Hill Air Force Base was as we went
19:14:00 3|j down through this process and looked at and evaluated the
site Hill Air Force Base being the site. We were listed
on the National Priorities list, which is the Superfund
listf if you will. That sort of kicked in the rest of this
road to the Record of Decision, which is what we are working
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towards and asking for public comment on that decision.
We've been through extensive work here to look at
investigating this site, trying to understand what
contamination exists there, looking at the feasible
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and finally reaching a Proposed Plan. This Proposed Plan is
the Air Force's proposal on how we would like to proceed in
cleaning up the site. The Proposed Plan is where your
public comment is so important, because we want to know what
your feelings are and if there are any concerns about our
proposal from your perspective.
From here, we will finalize the remedy in what is
called the Record of Decision, which is a legal document
requiring the Air Force to enact the proposal. And then, we
go through a design phase, a remedial action phase or a
construction phase. Then we'll operate that for a period of
time until such time as we clean up the site. Then it will
25 be delisted from the Superfund list.
KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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It is important to recognize that this process
will take a number of years to do the design work associated
with the project. It is important to understand that the
construction will take a number of yearsf and there will be
a number of phases associated with the project that will be
implemented.
I think people, in my discussions with them, have
felt like we would come to a decision and we would go out
and clean up the site and, in a year or two, the site would
be cleaned up. These sites are very complex. It is
important for you to understand that it is going to take a
long time to clean up these sites. We want to be
straightforward and make sure that you understand that this
isn't a simple one or two year fix. It will take many years
to clean up these sites.
The other thing I wanted to make sure you
understand is that we feel we have gathered together a group
of some of the finest engineers and scientists in the
country, including our counterparts with the EPA and State
Department of Environmental Quality, to review and evaluate
the proposal and to work through this long process. But we
are at a point in time where we we are wanting to make a
decision.
We can't say that, in twenty years, that decision
will be the best decision. It is important to understand
KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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19:17:30 2
that this process does not end right here with the Record of
Decision. In five years, there will be a review done
associated with this site to evaluate its progress, and
maybe open it up to a new set of alternatives.
51 So, it is important to realize that the process is
6 going to go on and there will be additional opportunities
for changes and moving and flexing as we learn more about
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how well these cleanup alternatives are going to work.
We have not drilled any holes and, you know, put
in any ground water treatment systems yet. When we do that,
we'll probably learn some new things and may need to make
12I some additional changes.
1311 Again, as I mentioned, we are very interested in
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your comments. It is important. We have- been through a lot
of preparation for this meeting and it is hard for our
engineers, sometimes, to not talk engineering talk. So, if
you hear that, please raise your hand and ask a question so
that we can get the issues clarified. Thank you.
MR. KIRCHNER: My name is Kyle Kirchner and I have
been working on Operable Unit 2, what we are here to
discuss, for approximately the last year. Operable Unit 2
is located on the eastern part of the boundary, right here,
The Base boundary runs up to here, Davis-Weber Canal is
there, South Weber Drive is along here, 475 East is right
25 there, and we're now over at the school in this area.
KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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19:19:30 1|| Operable Unit 2 consists of two former disposal
21| trenches. They were known as Chemical Pit 3, and they were
unlined trenches that were dug in the soil and the waste
solvents, which was a chemical used to degrease the landing
gear on the aircraft, they were brought out here and
61 disposed of in these trenches, the way solvent was disposed
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of and from 1967 to 1975. And the solvents consisted of
trichloroethylene, or TCE as it might be referred to,
tetrachloroethylene, PCE, trichloroethane, TCA, and some
other solvents. It was estimated that between approximately
111! ten and a hundred thousand gallons of waste solvents were
121 disposed of in those trenches during that time period.
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The waste solvents have now migrated down through
the soils and pooled on a clay layer about 50 feet below the
ground surface. The shallow groundwater in this area flows
across the site and flows down to the out-Base 'area to the
east. As it passes over the pools, it dissolves 'into the
ground water, and that is why it gets carried over to the
off-Base area.
There was a treatment plant that was built,
constructed up here in this area. Its primary purpose was
to extract the waste solvent. That started up in October
!93 and, to date, we have pulled out about 30,000 gallons of
waste solvent.
At Operable Unit 2, which consists of areas
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19:21:30 3
off-Base that was included in the investigation, as well as
the trenches on base, we have identified three different
ground water zones. One zoner the yellow, is called the
41 shallow system. It carries those contaminants off in this
direction, into this shallow system. There is another
system over here that is separated by this knoll that we
have called the hillside system. We haven't found any
contamination in that system. Then the blue out here, the
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light blue is identified as the Weber River alluvial
system. That is the upper portion of that deposit out
there.
Then the next slide Ifm going to show is a
13 cross-section view, vertical view through the ground surface
14 that basically runs in this direction. It gives you a look
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inside the ground as to how these systems are positioned.
The shallow system right here, the trenches are located up
here, and that has now settled down and pooled in what is
represented here as a little triangle trough. Then the
ground water flows off this way and carries that
contamination in this shallow system about 30, 40 feet below
the ground surface, off Base and down toward South Weber
Drive.
The Davis-Weber Canal is located there and that is
above the shallow ground water approximately 5 to 7 feet.
So, the contamination from Hill Air Force Base does not
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KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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migrate into the Davis-Weber Canal. Then again, the
hillside system that we have shown is separated by that
31! knollf and any rainfall that falls, part goes this
4 direction, the other part goes in that direction, for those
5 three systems that we have. And then this is the shallow
19:23:30 7
alluvial material of the Weber River.
Then, for clarification purposes of municipal
8|| water for South Weber, where they might be getting their
9 drinking water, the wells the contamination that we are
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talking about with Operable Unit 2 is limited to the shallow
grouhd water that flows right up along here. There is a
12 couple* hundred feet of clay that separates this water system
13 from the deeper water, the Delta aquifer, which the city
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drills their wells in. So, down here in South Weber, that
is approximately 400 feet below the ground surface that this
source of water comes from.
With this slide, I would like to show the extent
of contamination we did find during the remedial
19 investigations. This is the TCE, trichloroethylene,
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constituent of waste solvent. It makes up 68% of that
solvent. We have mapped that from the source area, where
the pools of the solvent were, into the off-Base area that
goes beneath the Davis-Weber Canal. This is a pond that is
naturally occurring.
Then the contamination to the lighter colors is
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19:25:00 2
lower and lower concentrations. This light green here would
be between 1 and 10 parts per billion and increases in
3 increments of or order of magnitude, this is 1 to 10 and
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41 10 to a hundred.
As I mentioned, there were some other compounds
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with the waste solvent. This is tetrachloroethylene, PCE,
that has migrated off Base but to a lesser extent. This is
basically down heref the canalf and South Weber Drive.
This is another compound that was found there.
Again, it shows that it is in less extent than the
trichloroethene, TCE. The TCE is what we use to identify
the full extent of the area that needs remediation.
Once we have identified the extent of the
contamination, you look at what risk that poses to us as
humans and people who live within that area. We found that,
under the current residential scenario which means that
the way we developed that was that we said the spring water
or shallow ground water was used to irrigate crops. Nobody
was drinking that. So, when you have one excess cancer risk
in a million people, that would be one in a million, I
guess, chance to get cancer or have excess risk. That's
considered less than that is nonsignificant.
As you can see the current conditions, we are
in the average, everyday situation, we are at that level for
a child of 7, and then 3 in a million, slightly more. One
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l|| in 10,000 is where it is considered a significant risk that
2 needs to be looked at. Then for the adults, they are below
the one in one million.
However, what is driving the cleanup of the site
19:27:30 6
is the future residential scenario. That would be, if
somebody built a house in that pool area and drilled a well
into the shallow ground water and used that well in their
house for drinking, showers, cleaning the vegetables,
everything, and you are exposed up to 70 years. Then you
101! start adding risks that would be above the level here.
11 That's what is driving us to do the cleanup is to restore
12 that ground water so that it could be used for that
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situation.
UNIDENTIFIED VOICE: I have a question. Can you
put the last one back up? People that are living in that
area now, right in that section, what area are they? Are
they current on the site?
MR. KIRCHNER: Current off site.
UNIDENTIFIED VOICE: Are they considered off site?
MR. KIRCHNER: I should clarify that. "On site"
is on the Base and "off site" is everything outside of the
Base. It is off site, meaning it is on Operable Unit 2 but
off site. I guess the better thing would have been off-Base
residential.
COLONEL EMORY: Did that answer your question?
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UNIDENTIFIED VOICE: It did.
MR. KIRCHNER: Sof this overhead shows the long-
term noncancer-causing effects, such as skin rashes or liver
problems, et cetera. Againf we look at the current
off-site, off-Base residential scenario. For the children
and in adults, that is below the indicated level of one.
Looking at the future, to again use the shallow
water for drinking purposes, plunk it into your house, that
would be above that and that is what we
MR. PEEK: Richard Peek. How are these figures
brought about? Is this some formula, some idea that
ratchets this all together? What is the chances of getting
hit crossing the road? It is.not a big deal unless you are
the one that gets hit.
MR. KIRCHNER: There is a spreadsheet that puts it
all together. You look at the contamination you have. A
pathway, that would be ground water that you are drinking or
spring that you come in contact with. All those things are
put together.
MR. STITES: Type of chemical.
MR. KIRCHNER: All these things are looked at and
how you are exposed and the length of time. It is a pretty
complicated spreadsheet that takes into account breathing
it, ingesting it, putting it on the vegetables. It is a
complicated process.
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We do have some people that could expand on that
if you want that. But it is not this is what we think.
There is a formula or a format to follow.
UNIDENTIFIED VOICE: (Inaudible)...exposure time
and how you were exposed?
MR. STITES: There is a doctor in the
Administrative Record that describes how this is arrived atf
this assessment. It is about that thick. You know, if you
want to see all of the actual equations and what we know
about the toxicity or cancer-causing potential of some of
these chemicals, you can look at this. This is literally a
brief summary of all of that analysis that went into this.
COLONEL EMORY: This is the nationwide standard,
the standard equations used to direct risk assessment.
MR. STITES: These are EPA methods of
COLONEL EMORY: They are from the samplings that
have been taken at the site. It is from the EPA'approved
process for sampling the amount of this material that is on
site, and then applied to these equations so we have the
standard processes for determining the site-specific risk
associated with it.
MR. KIRCHNER: Did you have a question?
MS. ODEKIRK: Jenny Odekirk. I had a question on
the hazard index where is says "0.10 regulates potential for
human health." My question on that was, what kind of
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potential is that? Is that one in a million, one in two
thousand, or is it determined by what type of chemical
you're talking about?
MR. STITES: We are talking about a different kind
of effect when we are talking about noncancer-causing
effects. Like a skin rash or liver disease or potential for
mutation, something like that. And this 1.0, what this
number is is the ratio of the concentrations which you would
be exposed to over the number that represents the lowest
observed effect level.
In other words, if we had a set of test animals
that we increased dose onf found the level on which that
first effect occurred, that would be that number, that
lowest. Below that, we say we have never seen any effect.
Then there is a factor of safety put in there, and then it
is extrapolated to humans.
Have I answered it or muddled it?
MS. ODEKIRK: I.111 think on it.
MR. KIRCHNER: Okay. Again, the future scenario
is what is driving us towards the cleanup. We have
developed a number of alternatives that address the source
area, the on-Base area and the non-source area and the
off-Base area.
Each alternative was evaluated against the nine
criteria identified by EPA. The first one addresses whether
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1 the remedy provides adequate protection and how risks posed
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19:34:30 2J| through each pathway are eliminated, reduced or controlled.
The second addresses whether the remedy will meet all
federal and state environmental laws. These two criteria
must be met before you can move on and be considered by the
primary balancing criteria.
The balancing criteria, they form the basis for
comparison, allowing trade-offs among the alternatives. You
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know, require different degrees of performance. You can do
something that maybe assures a slight more margin of
reduction in massive contaminant, yet it costs a hundred
times more. So then you run that through and look at how
that affects the protection of human health.
The third one referred to ability of a remedy to
provide reliable protection of human health over time.
The fourth one refers to a preference for a remedy
that reduces health hazards and contaminants, movement of
the contaminant, or the quantity of contaminant through
treatment processes.
The fifth one addresses the period of time to
complete a remedy and any adverse effects on the human
health or environment during the construction or
implementation of the remedy.
"Implementability" refers to the technical and
administrative feasibility of an alternative remedy. This
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1 includes the availability of materials and services needed
2 to carry out that remedy. It also includes coordination of
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federal, state and local government efforts.
And "Cost" evaluates the estimated capital,
operation and maintenance costs, and each alternative in
comparison to the other equally protected alternatives.
Then the modifying criteria, what we're hoping
from the community, is whether they support the technical
effort to restore the site, and also the state's
acceptance.
So then, for the source area and the on-Base area,
there were twelve alternatives that were compiled that would
address the contamination in that area. Going through the
nine criteria, five of them were selected for detailed
evaluation.
The first alternative of "No Action," that is just
monitoring of the site. That is included in the process by
law. We have to consider that one. So essentially, we have
four active alternatives to restore the ground water and the
soil in that area; that is, 4, 5, 11 and 12.
Then in the non-source area, the off-Base area,
there were seven alternatives developed. They were screened
through the same nine criteria. Four of them passed the
screening. And again, there is a "No Action" alternative
that is carried through, and that is by law. So then, we
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l|| have alternatives 3, 7 and 5. I will be addressing the
211 source area ones first.
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Source area alternatives would include a number of
ground water extraction wells. That would be to lower the
ground water in this area down towards that clay layer that
is 50 feet below the ground surface. We would have
extraction wells placed around here that would vent vapor,
and we would have injection wells that would inject steam
down into the former pools, contamination of waste
solvents. That steam would migrate and volitilize these
11 compounds and move them to the extraction wells which would
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pull that vapor out of the ground. It would also include
monitoring of the ground water that was described in the
earlier alternative, or No Action.
No Action would have ground water monitoring to
see what the extent of that contamination wasf what it was
drawing or producing. That would be taken to the treatment
plan that is there, the Source Recovery System. That would
be treated and then it would be pumped over to the
industrial treatment plant on Base and it gets further
treatment and is taken off to the North Davis sewer.
Alternative 5 consists of everything that was in
Alternative 4, the steam injection, steam cleaning wells
with the vapor extraction wells, the dewatering wells here.
However, it would also include a trench, or another method
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is to construct a vertical wall that is tied down into that
clay layer. Sof if we have these pools here, we would
3|| install a wall to the material down into this ground water
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to prevent any migration down over the hillside from the
Base. That's what this wall would do. It would limit that
migration.
Alternative 12 again consists of I'm sorry.
Alternative 12 consists of a completely encircling wall. We
would put that wall completely around those waste solvent
pools. They would be tied down into the clay layer. It
would prevent any ground water from entering this area and
also prevent any contamination from leaving the area.
Where the former trenches were, this area would be
excavated down to 20 feet below the ground surface. It
15 would be treated on site and backfilled. There is potential
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for some minerals associated with those pits and they would
be solidified and placed back in place.
Instead of injecting steam into these areas where
the pools used to be and extracting them as vapors as it
swept toward the extraction wells, we would have injection
wells of water and we would flush water through here and
extract them out at these other wells. So, it would be like
a washing aggressive washing type of process.
Finally, for the source area, Alternative 11, this
is the one that is preferred by Hill Air Force Base. It
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consists of a completely encircling wall. That would be the
trench that is dug down into that clay layer and a mixture
of clay would be installed, or we could use steel sheet
19:42:00 4JJ piles that could be driven from the land surface down into
that clay. In this alternative, it would again consider the
steam injection or steam cleaning-type process to get at
those waste solvents that remain behind. It would also
dewater that area through the wells that we have in place.
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But in addition, we would place a cap across the area that
is completely encircled. It would be a clay cap or a
texture fiber texture-type of cap, geomembrane cap. That
would limit any human exposure to these soils that are in
13 those areas of the trenches.
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The reasons for selection of the Alternative 11 or
why we would prefer that, it totally encircles, while
alternatives 4 and 5, the ones I showed earlier, do not
completely contain the waste in a passive manner/ That
would mean, power failure of the pumps or anything like that
that would happen, we would lose control of that site. The
ground water would migrate. Where, if you have a completely
encircled area, we eliminate that type of contamination. It
eliminates more TCE than the other alternatives. It does
not include any excavation of the soil with the potential of
releases into the air, dust generation from that
alternative, which would be carried elsewhere.
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And as far as the cost, all alternatives were
comparable.
In summary, we feel it is most effective for human
health and environment; that isf the source area and on-Base
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area.
In the off-Base area, the non-source area, we have
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three alternatives that were carried through that are
considered active or aggressive in cleaning this up. The
blue that I've outlined is that extent of the contamination
I showed you with the one side of the TCE. The
Alternative 3 would involve installing a number of what is
known as air sparging wells, which would inject or blow air
down into the ground water. This would be constructed into
the ground water. Then you would have a row of soil vapor
extraction wells, wells that you draw vacuum on and suck the
vapor out of the soil material. As the air is bubbled into
the ground water, contaminants are in those air bubbles and
brought to the surface and extracted through the vapor
removal wells. It consists of a number of rows with quite a
few wells that are located along each row.
Then, Alternative 7 for the non-source area, it
includes the air sparging wells that I described, in the
center portion of the plume. However, at the north end,
over toward the east, we would install a normal well that
pumps the ground water out. That would capture the
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1 contamination in these areas and limit any further migration
2 of that contamination. We also have a trench that we would
3 install up near here that is at a spring that has some high
II
41 concentrations. We currently have a shed there where we're
treating it now.
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Then lastly for the non-source area, this is the
alternative that is preferred by Hill Air Force Base. It
would involve using only wells.to capture the contamination
in the off-Base area. At this time, they are shown on the
map, nine wells that later will be defined during the design
phase, the exact number of wells and the positioning of
these wells.
We felt that this technology, extracting the
ground water through the wells, is most reliable. The air
sparging, there is some debate about its effectiveness.
This has a slightly less impact on the land surface or on
the land that those would be installed in.
Then, the reasons that we do prefer that, I
touched on a few of them, but as far as it removes and
destroys the most contaminants, the air sparging does not
include treatment of that air for air emissions. I guess,
22 by "remove and destroy," we mean remove from the ground
23 water and actually destroy it at some point. That air, by
241 the air sparging, would be captured and taken off site or
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off the non-source area, the off-Base area. But those would
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be vented to the atmosphere. Much less intrusive to the
property owners, the equipment that would need to be
31 installed. Then; there is some question about the
technology of air sparging.
The costs were relatively the same. And again, we
feel like this is the most protective of human health and
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environment than the alternatives.
So, in summary, of all the alternatives that were
considered, the costs that are shown here represent the
amount of money that you would have to put in the bank today
or the day we begin to construct these alternatives. The
ones highlighted in green are the ones that we prefer. You
can see the cost range in the source area is between 19 and
24 million dollars, and in the non-source areaf it is
between 11 and 17 18 million dollars.
So, with that, I would open it up for questions.
MS. PETERSEN: Iris Petersen. I!m wondering, we
are in that area where it is leaking down into our area.
How much worse is it going to get as you are doing this? Is
it going to continue to migrate down and be worse as you are
fixing it, for years to come?
MR. KIRCHNER: I guess, to address the first
question, I think this is the field that we1 re talking
about?
MS. PETERSEN: Yes, right across the road.
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MR. KIRCHNER: This is, I think, the other part of
the property?
MS. PETERSEN: That's in our field.
19:49:30 4|| MR. KIRCHNER: Right. Once we begin
5|| implementation of these actions, we'll actually be drawing
this contamination back towards the heart or towards the
higher level of contamination, back towards the source.
Once these actions are in place, it is not going to spread
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any farther. We'll be monitoring that to evaluate that.
That's our primary objective, is to limit the spread of this
11 contamination and get this out of the soil to reduce any
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more exposure to what is already there.
MS. PETERSEN: And how many years do you think it
will be before you actually implement?
MR. KIRCHNER: To actually implement this, we are
looking for the on the alternatives tonight, we are
looking for the approval and to move forward. Then we will
prepare what is called a Record of Decision. That is where
Hill Air Force Base signs a contract, basically, with the
EPA and the state on which method is acceptable, the chosen
alternative. We have 15 months, by law, that we have to be
out implementing a remedial action, the technology to clean
that up. So, that would be December '95 we would be in the
field. Then we have a couple of months well, more than a
couple of months. Probably six months to two years to
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19:51:00 4
construct the alternatives, depending on what they are, to
drill the wells f connect the piping and ran it up to Hill
Air Force Base.
MR. ELLIOTT: Well, it is important to realize
that December is in the middle of the winter, and we'll
6 start what we can, but heavy construction really wouldn't be
7 able to start until the following spring because of the snow
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and weather conditions. We will have some limitations on
when we get started.
MS. PETERSEN: You know, we're talking about the
11 future. What about back when we were using water to water
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our lawns and different things? Is the danger there higher
than it was than it is now?
MR. KIRCHNER: Well, the danger, I guess, so to
speak, is growing each day. I mean, every day that we don't
do something, that ground water carries the contamination
farther. So, if we go back in time, this would get smaller
and smaller.
So, you know, Ifm just taking a guess here, but
five years ago or whatever, this darker green may have been
where this lighter green is now. Or ten years ago, I don't
know exactly what that would be. You know, it is getting
worse by the day, so to speak, but it is not what I would
say, you know, is it is not going to migrate and be under
your house and be six miles away and you will be in the
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19:52:30 l|| worst part of it. This is moving very, very slow. It is
not posing any health hazards to people living there.
MR. ELLIOT: Bob Elliot again. How many feet a
year or a day would you estimate this is moving?
MR. KIRCHNER: We have limited data to get a
19:53:00 6|j precise number on that. We have a year's worth of sampling
7II data that shows, in this area at one point, we do have some
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contamination by this well here, and then it moves back.
With grade fall patterns and absorption of these chemicals
into the soils, the outer trenches of this plume is maybe,
if wfe want to put a number on it, five feet in a year or
something like that.
MR. ELLIOTT: That was the point I was trying to
make. It is moving in feet per year, feet per month. It is
not moving in miles per day or anything. It is moving
fairly slowly. I think that can be represented' by the fact
of how long those solvents have been there and the amount of
time it has taken for them to move as far as they have. So,
that gives you some framework to understand how fast that
might be moving.
MR. KIRCHNER: 'it has taken 1967 to 1967 to
221 1975 is when those chemicals were disposed of. So, we have
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twenty years to get to this condition.
MS. JONES: Pam Jones. I'm not sure I
understand. Are you saying it was worse five years ago or
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worse now?
MR. KIRCHNER: It was it is worse now than it
19:54:30 3JI was five years ago.
41 COLONEL EMORY: The reason for that is that it has
51 moved from on Base to off Base in the last twenty years.
When we say it is worsef what we're talking about is that
the concentration we have is gradually creeping along. From
that standpoint, it is worse.
10
MR. JONES: What this lady was saying before, when
she was watering and using that for her vegetable gardens.
11 five or ten years ago, she is at more risk now than she was
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four years ago?
MR. RAY: Ivan Ray. How many off-Base operable
sampling units do you have at this present time,
approximately?
MR. KIRCHNER: Off-Base areas that have
contamination?
MR. RAY: That you are doing the sampling.
UNIDENTIFIED VOICE: Wells.
MR. KIRCHNER: We have a number of Operable Units,
we are calling them. We have this is No. 2. We have 1
through 3.
MR. RAY: You have eight sites?
COLONEL EMORY: You are talking about in this
particular
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MR. RAY: No, totally, along the whole spectrum of
the cleanup process, not just those two.
MR. STITES: We have eight defined to date.
MR. KIRCHNER: The number of wells that that
involves, I don't know. I know that we currently sample
19 wells associated with this, and ten springs, if they are
flowing or wet or if they have water there. So, we have 29
sampling points associated with this operable unit that we
sample four times a year and take water level measurements
out of the wells on a monthly basis.
MR. RAY: Ivan Ray again. Is there has there
12 been any determination to detect where the water sources in
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the aquifer 40 feet under that you are talking about, 40 to
50 feet, where those sources are that is moving the
15 contaminants? If so, has it been determined, can anything
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MR. KIRCHNER: I can address Operable Unit 2.
That is what I'm managing and what I know. The Base this
here is the Air Force Base property. As we know, it is all
on top of the Delta River formation, so it is kind of a high
point in the area. In this area, you get precipitation that
lands in the vicinity of that Operable Unit 2. So, any
precipitation that falls in this area infiltrates down
through the ground and pools or, you know, hits an
9:57:30 25 impermeable layer and forms the water table.
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So, in this area, there is a topography that
controls, and so it takes the rain that has fallen on the
east side of the runway, and that's what creates that
shallow ground water. Then it moves off-Base.
MR. STITES: Were you asking about the source of
the ground water or the source of the contaminants?
MR. RAY: No, the source of the water that is
moving the contaminants. And about how much volume of water
are we looking at? Is there any determination of that?
MR. KIRCHNER: No, I don't know.
MR. SMITH: Phil Smith. You estimated the flow
rate that we would need to extract out, which is roughly the
same amount of water that would be pushing this, 200 gallons
a minute for the whole extraction system?
MR. KIRCHNER: For the whole site?
MR. SMITH: For the whole site.
MR. COOPER: Louis Cooper, Davis County Department
of Health. What is the level of competence on that clay
layer that you discussed, on your slurry wall and cap? It
has been a long time ago, and maybe Bob remembers, but
Operable Unit 1, where they put a slurry wall and cap in,
initially that was thought it would control most of the
off-Base migration. Due to the resistivity testing, they
were relatively confident that they had a clay layer in the
same level that you are talking about. To my knowledge,
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they had some upward migration that continued to move it off
site. They picked up galleries (sp) to collect it and take
3II it and treat it. Is this site different? What is your
19:59:30 5
level of confidence on that clay layer and your upward
migration of the deeper water under that shallow pool?
MR. KIRCHNER: That clay layer is several hundred
feet thick. We have sort of different contaminations. Bob
can probably address what happened at Operable Unit 1. He
is more familiar with that than I am.
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At this site, though, we're not looking this
clay layer has held. We have actually held that waste
solvent there for 20 years or more. So, as far as that
going down any farther, we are pretty confident there.
Looking at the horizontal movement, that moving off-Base,
we're looking at a number of different technologies.
What was used at Operable Unit 1 was where they
dug the trench and backfilled that with a clay mixture to
form a less permeable wall. We are also looking at steel
19 sheet piles. That's where you have like a 60-foot long
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piece of metal that is Z-chained and has interlocking
grooves on it. You would connect those one-by-one, drive
that down, connect the next one, and you would seal that
joint where those interlock.
There is ways to construct that containment wall
that is a little different than digging the trench and using
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a mixture of clay and native material. There is other
methods where there is big augers that can drill down, and
20:01:00 31| as you drill and move those augers back and forth through
the soil material, you can inject clay or soil mixture and
get a good consistent integrity wall. There are things at
Operable Unit 1 that are unique and different from this.
8
MR. ELLIOT: Bob Elliot. Let me explain. In the
1985 and !86 time frame when we constructed that wall, we
9 constructed that in a response action, recognizing that
20:01:30 10 there was contamination coming out of coming out into
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some springs along the hillside. When the wall was
constructed, we had somewhat limited geologic data at the
time that was constructed.
But the primary thing we think that caused
problems associated with that wall was, the contractor who
20:02:00 16 was constructing that wall, we had a hundred percent
17 inspection of that wall for the entire period of the project
18 except for one week when the inspector was on vacation. As
19 we went back and looked at the boring log or the logging of
20 that wall, the depth, his logs, what we call "straight
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lined." There was no more we no longer saw him following
the contour of the clays to tie into those clays. So, we
feel that the primary reason that wall isn't as effective as
it could have been was because the contractor didn't
25 actually dig it down into the clays.
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Kyle is talking about, with Operable Unit 2, going
into the clays a number of feet to insure that it is tied
down into the clay. There are some sand lenses that exist
41! in those clays. We have much stronger geologic information,
20:03:00 5
8
bore holes that have been drilled down into the clays to
understand what they look like and what the potential is-for
water to go around and short-circuit underneath those
walls.
Even if it didf that's okay. There is nothing
10II wrong with that, because with this proposal, the water would
11 simply be extracted from inside of that wall and treated.
12 MR. RAY: Ivan Ray. Approximately, on Base,
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through the years, how many disposal sites were there? Do
we know about how many there were?
MR. KIRCHNER: There are a number of disposal
sites. Operable Unit 2 just happens to have one set,
Chemical Pit 3, that consisted of two trenches. Operable
Unit 1
MR. ELLIOT: Six sites.
MR. KIRCHNER: Two or three landfills, a fire
training area, a waste phenol-type of oil.
MR. ELLIOTT: Operable Unit 1, there are two
landfills, two chemical disposal pits, two fire training
areas and one waste phenol oil pit.
MR. KIRCHNER: Then here we have Operable Unit 4
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that is a landfill. Operable Unit 3, I think is some
stormwater ponds that have been backfilled. So, I don't
MR. RAY: It would be around 10?
MR. STITES: More than that. As a rough order of
magnitude, I would say dozens
MR. KIRCHNER: Those are individual
THE REPORTER: One at a time, please.
MR. RAY: Sorry about all these questions, but in
effect, if there is a base closure, what effect would this
have on the program as it is thus in place now, or would it
be dissolved, or has the government provided something to
finish taking care of the situation if that takes place?
MR. KIRCHNER: If the Base closure happens, before
that property can be turned over to private industry or the
public, each site would have to be remediated before that
property can be turned over. So then, I guess we're talking
about a matter of how quickly or how aggressive do you want
to do it to meet that criteria, based on the committee that
evaluates that. I think that would
MR. ELLIOTT: Bob Elliot again. The money
associated with this program is no different than the
Superfund which provides money for private sector sites.
This funding, however, was set aside by Congress for defense
sites. The funding will continue to be there as long as
Congress continues to pay for the program.
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MS. ODEKIRK: How deep were these trenches, and
were they just earthen trenches or were they lined?
3II MR. KIRCHNER: They were unlined, just dug into
4II the ground, probably about ten feet deep, just in the
20:06:30 5|| shallow soils. The solvent that was collected, after they
degreased and cleaned the landing gear parts, was collected
8
in drums and taken out there and disposed of in those
trenches. Those trenches were above this clay layer we are
9 talking about. They were 10, 15 feet at the most.
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deep'?
barrels?
MS. ODEKIRK: The trenches were 10 or 15 feet
MR. KIRCHNER: Right.
MS. ODEKIRK: The contaminants were stored in
MR. KIRCHNER: They were actually emptied into
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those trenches, transported in barrels. That was at the
time, that was the.accepted disposal practice. It wasn't
midnight dumping.
COLONEL EMORY: Just like people used to drain
their oil pumps in the cars, drain them in the back yard in
the grass. That wasn't the mentality where people get
interested in the ground water.
MS. ODEKIRK: It was stated there was between ten
and a hundred thousand gallons of contamination?
MR. KIRCHNER: Yes.
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1 MS. ODEKIRK: How come that is such a wide scale?
2 MR. KIRCHNER: Because there was nobody at these
3 trenches to keep a log to say so-and-so brought a 50-gallon
4 drum and disposed of it this day. What we had to do was go
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back and go through the use of that solvent and say, if they
cleaned this many airplanes over this period of time we
tried to estimate how much did they recycle, catch and try
to reuse. The hundred thousand would be if they sprayed the
parts and ran it into the collection drum, and the ten
thousand is if they sprayed the part down, and it wasn't
that dirty, so the solvent could be reused. We don't really
have any record of what was taken to these trenches to be
emptied.
You know, based on earlier comments I said, from
the system we had on site that started operating in October,
we pulled out 30,000 gallons. We have learned'a lot. We
know it is more than ten thousand. It has to be more than
30,000. We are probably in the upper range of fifty to a
hundred thousand gallons. What we pull out is only going to
be a fraction of what remains there. The chemical absorbs
in the soil. So, when you pump, it doesn't come out
immediately. So, you know, 30,000 is a percentage of what's
there.
MS. ODEKIRK: You are saying, what you pull out is
only going to be a fraction. What you pull out in long-
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term?
MR. KIRCHNER: With the system we have today.
3| These actions address the whole part of the contamination.
You.know, at this sitef remediating TCE out of the soils,
there is no proven technology to meet what is considered the
maximum contaminant level for drinking water, the MCL of
20:09:30 7 five parts per billion. There is no technology out there
8
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that can do that in a short period of time. We are putting
forth the best knowledge that we have today. And you know,
five years from now, we may come up with a better technology
that can go in and get that stuff like that, in a year's
time.
13 For the source area, we are looking at thirty
14 years to clean that up. That level is probably thirty-plus
151 years. In the nonsource area down in the fields, we are
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talking about we have developed those alternatives, but a
15-year period for remediation.
MR. STITES: I would like to interject something
here along the same lines. EPA's experience with this kind
of contamination, that we refer to as a DNAPL, is that it is
very difficult to extract or remediate. In fact, in many
cases, it cannot be fully cleaned up. In.those cases,
sometimes the best we can do is some sort of containment
around it and to try to prevent exposure, minimize the
ability of the contaminants to move and affect anybody
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else.
If that does turn out to be the case here I
mean, the Air Force is proposing technologies to go after
this as aggressively as possible with what we know now. But
20:11:00 5JI I also think it is only fair to get it out there that, even
II
with all of that, the aggressive attempts, we may not be
that fully successful. If that's the case, we may not be
able to clean up to the ground water drinking water
standards in that immediate source area. That would not
101 apply to anything off Base, but strictly in that source area
11
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on Base.
MS. BON: Peggy Bon. I'm a relatively new
resident of South Weber, so Ifve got a lot to learn.
141 Operable Unit 2, that implies there are others. We have
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heard about Operable Unit 1. Where are the other units?
How many are there and where are they and what problems do
they have?
MR. KIRCHNER: This identifies all of the Operable
Units that we have. I'm the project manager of Operable
Unit 2, so I don't know all of the specifics of every other
one. But at least this will give you an idea where they are
located. I guess Operable Unit 4 let's see. Davis-Weber
County line, I think runs right in this area. Bob, is
MR. ELLIOTT: Let me help you out here. We have
had him focus so much on Operable Unit 2, he hasn't had a
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,20:13:00 8
1|| chance to be involved in the others.
21 Operable Unit 4, the Riverdale City/South Weber
City line runs right through that area. So, it is
essentially split into two cities, if you will, city
boundaries.
Operable Unit 1 up here is in the City of South
Weber. Operable Unit 2 is in South Weber. Operable Unit 6
is also in the city of Riverdale. Operable Unit 5 is in the
city of Sunset. Operable Unit 3 excuse me, Operable
10 Unit 8 moves off Base into the city of Layton. The rest of
11 the Operable Units, 7 and 3, are on-Base areas. The soil
12 contamination
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MS. BON: What does that mean? Does that mean
they found problems in those places?
MR. ELLIOTT: We have found ground water
contamination in the shallow drinking water excuse me,
shallow nondrinking water aquifer that is maybe 10 to 40
feet deep in areas surrounding the Base. Many of those are
adjacent to disposal areas. Some are adjacent to places
where operations were conducted, where solvents were spilled
on the ground associated with those.
MS. BON: Were those part of this cleanup?
MR. ELLIOTT: Yes, we have an extensive schedule
with the EPA. We have an agreement with EPA and the State
Department of Environmental Quality to address each one of
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1 these sites. They are all tracking on a different schedule
20:14:30 3
than Operable Unit 2. Operable Unit 4 has already is
currently they are currently signing the Record of
Decision for that. It is at EPA. That public meeting was
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5|| held last year.
Operable Unit 2 is next on the list. So, there is
all of these sites tracking on a different schedule. That
has been a function of how much or when we found the
sites or found the contamination, I should say, and how fast
we have been able to investigate it.
MS. BON: Thank you.
COLONEL EMORY: We have meetings on a regular
basis out at Hill Air Force Base with people throughout the
community, but primarily all of the agencies involved in
this remediation effort EPA, Water Conservancy Districts,
all that sort of business on a quarterly basis where we
brief all of these simultaneously, current status and so
20:15:30 21
forth.
MR. ELLIOTT: We also meet with each of the city
councils on a semiannual basis and brief them on our
progress and what we are doing. You could contact your City
22 Council, or if you are interested in meeting with us
2311 MS. BON: I only knew about this meeting because I
24II happened to buy a paper one day when it happened to be in
251 the newspaper. How do you know these things are happening?
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MR. STITES: Rob Stites. You can get placed on
the mailing list and you would have been mailed a copy of
the Proposed Plan. Also, you would be getting copies of our
fact sheets and news updates that Hill puts out as it comes
20:16:00 5II out.
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MR. ELLIOTT: If they have signed up back here,
won't they automatically be put on the mailing list?
MS. BREWER: Right.
MR. ELLIOTT: If you sign up and put your name on
the list at the back, you will be put on the mailing list.
MR. KIRCHNER: What we did for this Operable Unit
is, we tried to identify the people that lived in the
vicinity the best we could.
MS. JONES: It is on our agenda. It is posted at
20:16:30 15 our meetings in the City Office.
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MR. ELLIOTT: Let me also make sure that we we
have answered a lot of questions, and that is terrific that
the people have these questions. I think it is important
that this is also a forum where you can voice concerns or
make a public comment, and then it will go into the record.
If you don't want to write a written comment, this is a
forum where it goes into the permanent record associated
with this site.
I want to make sure I don't want to get lost in
answering questions. I want to make sure that, if you have
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20:17:30
l|| concerns associated with this project, that you realize that
2 this will, if you do make a statement here, go into the
public record.
MR. PEEK: Question for Mr. Elliot. Last year
5II when we had this other meet ing, I gave you my name and
address to have some ground water that was coming off the
hill tested, and I have not been contacted at any point.
You mentioned that you would get with us and test this
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water, because and that brings up another question about
the Weber-Davis Canal. How can they say that this does not
contribute to the ground water problem unless you have gone
12 up and inspected that canal when it is empty? This spring
13 runs very well when that canal is full. When it is down, it
14 tends to dry up.
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MR. KIRCHNER: When I mentioned earlier that it
didn't contribute to the problem, the contamination does not
go into the canal. However, the canal, as all concrete
canals that age and the type of construction, they leak.
The canal, by leaking, actually spreads that contamination
farther.
MR. PEEK: That makes better
MR. KIRCHNER: The canal doesn't impact our
contamination.
MR. PEEK: The other way around.
MR. ELLIOTT: Let me address the first question.
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II apologize for that, if we haven't taken care of that. If
21 you get together with me, we will take care of that sampling
3II you want.
MR. PEEK: They mentioned the plume was going more
westward toward Darren Cutler's home. I'm from Operable
20:19:00 7
Unit 4. They mentioned that it was going more that way.
But just to be safe, because the state has piped that ground
water and it runs over into our agricultural drain across
the road. So now, we are being exposed to that. If there
lOJI is not a problem, great.
II
11 ' MR. ELLIOTT: We would very much like to do that,
12 because that is our goal is to make sure we understand where
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all this ground water is going. We want to control that.
We'll get out there and take care of it.
MR. PEEK: Thank "you.
COLONEL EMORY: Make sure you put that on the
sheet that you have, your name, number, location and your
18 concern, so we can get this to hang onto to track.
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MR. RAY: Ivan Ray. One more question and I'll
shut up. According to the study I read, CHM Hill, 21
December 93 I know many of the people here are affiliated
with that. It cited that there were both upper and lower
hill sliding, and that there were wet spots on the hill.
And in lieu of the fact that there has been on-site
inspections on the surface of the hill movements, yellow
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green sludge and odors andf I'm sure, chemicals, both above
the Davis-Weber Canal and below the Davis-Weber Canal above
the Bamberg Irrigation Company canal, what effect is this
4II hill movement and sliding having on the 40 or 50 foot
20:20:30 5|| aquifer underneath? Is it possible that aquifer is leaching
some of it out both above and below the canals as the result
of the hill movement? Is there any studies? I know, in the
report, there is going to be some testing, drilling of, I
guess, test holes 150 feet into the hillside. I don't
101| know. That was proposed, but I don't know where it went.
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MR. KIRCHNER: I think the area that we're talking
about is outside Operable Unit 2. I think that is more to
the southeast, closer to the hill cut, probably down in this
area here. So, I don't know all the answers to that.
At Operable Unit 2, we did drill a
several-hundred-foot boring down into the clays. We
installed what is called an inclinometer. That is a pipe
with grooves on it. It is almost like a compass, a
gyroscope, so you can tell if that hillside is moving. This
summer, this spring, we installed one of those inclinometers
at Operable Unit 2. I think that is outside of the area
that you're talking about. I don't know.
that?
MR. RAY: There is no updated information on
COLONEL EMORY: How about going ahead and putting
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that question down as a matter of record on there and then
our experts working in the other Operable Unit can give you
the detailed answer.
MR. RAY: I appreciate that.
MR. ELLIOTT: I might just mention, because it was
mentioned about the Davis-Weber Canal, the goal is to reline
the canal. They are putting drains underneath that to catch
and collect, and divert the water to central areas. However,
in the winter months, water comes in off the hillside, off
UDOT state road, goes into the canal, breaks under the
concrete in the bottom. There is a problem of surface water
coming into the canal that has broken the floor of the
canal. There is they are all working on that and there
is cooperation with Hill Air Force Base on some stretches
that we have been working on.
MR. KIRCHNER: Yeah, we'll work on in the areas
that have contamination, we will be glad to work jointly
with collecting that. That helps everybody. If we can
contribute this to collect contaminated ground water for our
purposes and meet your purposes, it is all the better.
I thank you for participating in the public
meeting. Again, the comment period is open until June
llth. So, if you can think of anything else, please submit
those. You can call me, write me. I think my name is on
the Proposed Plan. Also, Rob Stites, EPA, and
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20:23:30 1|| MR. COY: My name is Lynn Coy. What effect does
21! this have on vegetation or livestock and food consumption in
3 those areas? Has testing been done to see if that is safe
4jj for consumption, or is it something we should discontinue,
and can it continue to be used for agricultural purposes?
MR. KIRCHNER: When I showed that risk table that
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shows the current use, vegetative uptake was considered in
those scenarios or pathways for that. Under the current
situation at Operable Unit 2, since we are not spraying any
shallow ground water up on those crops at this point, there
is no reason to be concerned.
MR. COY: What system do those crops or food
sources bring those contaminants to the surface in the
vegetation?
MR. ELLIOTT: Bob Elliot. The agricultural
community, in conjunction with the environmental engineering
community and environmental science community, has looked a
lot at that whole process. Because the chemicals that Kyle
is talking about are volatile, they tend to evaporate very
easily. They are kind of like gasoline. If you were to put
them in a pan and came back in the afternoon, it would be
gone. They evaporate very quickly. If you were to spray
that water on something, those chemicals just evaporate into
the air. So, that's not a problem.
From pulling the ground water out of the ground,
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the scientific community, because of the type and nature of
the chemical, does not see that as being a concern. These
31! are not the types of chemicals that the plants take up into
20:25:30 4|j their system and then are accumulated in the plants.
MR. COY: So, you are saying that it is safe to
continue to use that for agricultural use for both human
consumption and animal consumption?
MR. ELLIOTT: I think the key would be I guess
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I'm not sure that there would be a problem with you growing
alfalfa and feeding it to a cow. There is no indication
that'there would be uptake. In vegetables, we don't think
there is any uptake either. The problem is, there is no
real good data out there to say, look, we've looked at this
and it doesn't occur. But the scientific theories say that
it won't occur. We can't say, here is a study and it says
it won't happen. We are currently working on doing a study
like that to demonstrate that.
I guess I was hedging because I think, if we wait
for six to nine months, we'll have some information and we
can definitively come out and say this isn't a problem. But
the scientific community has sort of said it is not a
problem because of the type of chemical. But that doesn't
help you, because there is no real data out there to say it
doesn't happen.
COLONEL EMORY: I think we've actually done tests
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20:27:00
on fruits and vegetables at one or more of our Operable
Units, right? And it essentially revealed only trace
levels, if in fact, I don't even know if those showed
41 up,
5
6
MR. ELLIOTT: We didn't even see trace levels.
COLONEL EMORY: It isn't just all out of a book.
We have actually analyzed the vegetation stuff. We have
been in actual Operable Units like that. I don't know if we
have done it on Operable Unit 2, but we have conducted some
20:27:30 10II tests and we haven't found anything, yet, in fruits and
11 vegetables.
12 MR. COY: Are you recommending I can continue to
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use it for agricultural use, or discontinue that? Ifra
currently doing that. If I am creating a potential health
hazard for someone, I would like to discontinue that. I am
currently using that for some of the produce for human
consumption.
COLONEL EMORY: Why don't we take a hard look at
the official Environmental Risk Assessment on that.
MR. KIRCHNER: I will look at that. There is an
exposure scenario that had some vegetative conditions.
There is a big spreadsheet on those pathways, that you may
have alfalfa growing and feed that to a cow and you eat that
cow directly, or if you are growing a vegetable and you are
eating that directly. So, without looking at that table and
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KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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20:28:30 1
20:29:00 8
knowing which ones they have specifically identified I do
know, I saw a summary of that and there was a vegetable
pathway in there that was considered the current scenario.
It showed it as the levels that were below. So, there is no
risk, no worry right now. If conditions are changing, I
think that is an important point that we be aware of. I
think we are talking about asparagus.
COLONEL EMORY: We need to get with the
9 Environmental Protection Agency folks and make sure we have
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the right standards and the right words to clearly tell you
what the level of risk is, or the lack of.
MR. KIRCHNER: We can take a sample and
specifically address this issue for that concern, if that is
what you would like to see happen.
MR. STITES: At present, we have got nothing to
suggest that you are causing anybody a problem or that you
should stop. Is that specific enough for you?
MR. COY: Yes.
MR. STITES: We came from one segment and another,
and I don't think we hit the question you were asking.
MS. JONES: Pam Jones. Can they take a sample of
his harvest now and do a test to let him know if he is
endangering his family? Instead of waiting nine months, can
they do that now?
MR. KIRCHNER: We can collect that sample now.
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COLONEL EMORY: Any idea, rough order of time
span, for what it takes to do a test and get it back?
MR. ELLIOTT: I understand your it is not just
as simple as going out and taking pulling a carrot out of
51| the ground and grinding it up, because these are volatile
6 chemicals. If they are in this carrot and you grind it up
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in a blender so you can analyze it, you can imagine what
happens to that. It goes into the air. So, there are some
limitations on how much we can do.
We can certainly test that vegetable or type of
vegetable and look at it and see if we see any
contaminants. The study that I referred to is a very
detailed study that will really track a chemical, track TCE,
which is the chemical we are primarily talking about here.
It will track that through radio labeling and follow it and
see where it ends up, see if it actually goes into the soil,
17 into the system and into the vegetable. We can quantify
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exactly where that ends up.
So, it is not just as simple as just going out
tomorrow and getting a vegetable, to understand that
process. It is a very, very difficult scientific problem.
That is why we are looking at this detailed study. But we
can look at what is there now and see whatever level, if
there is any contaminants there. Did I help answer that
question?
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Ill MR. STITES: I would like to add one brief
2 elaboration. Rob Stites. At some of the other Operable
3 Units, we do have situations where gardens are being watered
11
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fruits and vegetables from those gardens and have not
detected anything. Those were higher concentrations than
are existing on the outer fringe of the unit.
MR. KIRCHNER: We can still address that issue, if
you want to. The test that he is talking about is very
exact. We can do it more gross scale than trying to grind
up a carrot and address it that way.
MS. BREWER: Does anybody else have any more
questions or comments. Rob, John?
MR. STITES: I wanted to toss out one last time,
does anybody have anything for or against specifically what
we are proposing here as the preferred alternative?
MS. BREWER: Think about it. You have your
comment sheets. You have all of our names and numbers.
There is a contact sheet in each package. If you think of
something after, don't hesitate to call or write or contact
us in some way. Colonel Emory?
COLONEL EMORY: I would like to say thanks for
coming out this evening and helping us with this process.
We111 try to, over the long haul, get this site cleaned up.
You are all part of the team that we are on, including all
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KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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of the federal agencies involved, especially the
Environmental Protection Agency.
3|| And Hill Air Force Base is recognized nationwide
20:33:30 4|| as kind of on the leading edge of applying technologies in
the environmental cleanup business. In factf Hill Air Force
Base, as you saw in the local news, won the D.O.D.
Environmental Management Award for installations and program
management. I think that's because of the great team
10
relationship we have with the community and with the EPA and
the state and local agencies involved in this. Because, as
20:34:00 11 opposed, unfortunately, to a number of other places in the
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nation, we have gotten great support from all of our higher
headquarters and agencies to bite off the biggest problems
we have got and focus our resources and get on with the
cleanup process.
Part of the agony of this thing, as we started
this presentation with, it takes a tremendously long time to
go through this process, even to really get started on
really spading the ground and putting in equipment to
initiate the cleanup.
One of those things is, as you saw in this thing,
the dollar cost on these things is really high. That comes
right out of the federal budget, right out of your wallet.
24 So, we want to as best as the technology is today, all of
25j| the experts we have out there, we want to make sure, when we
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KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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spend your dollars to try to clean up your area out here,
that we are really right on target on that when we start.
20:35:00 3II Like I said, there is very little in the environmental
II
41 business that is cheap nowadays that gives you a fast
cleanup. We are trying to use our resources wisely to clean
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up what we have done to you in the past.
Thank you very much for your time and effort.
(Whereupon proceedings were adjourned at 8:35 p.m)
* * * * *
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l| REPORTER'S CERTIFICATE
2
3 (I STATE OF UTAH
) ss.
COUNTY OF SALT LAKE )
6
7 I, SHIRLYN SHARPE, R.P.R., C.M. and Notary Public
in and for the State of Utah, do hereby certify;
That the foregoing transcript of the Public for
10 Proposed Plan for Operable Unit 2 was prepared by me from my
11 stenographic notes taken at the time of the proceedings
12 therein reflected;
13 That the foregoing transcript represents all
14 proceedings had of record at the time of the meeting;
15 And I hereby further certify that the foregoing
16 typewritten transcriptf as typed by mer is a full, true and
17 correct record of my stenographic notes so taken;
18 IN WITNESS WHEREOF, I have subscribed my name and
19 affixed my seal this 7th day of June, 1994.
20
21
22
SHIRLW SHARPE, RPR, CM
«**M k
I*UISJT rMOi& m
->A /V SHIRLYN SHARPE I
24 I /^pSafrA 824Scutfi853E2St I
BOUHBM, utsh c.:oio I
'-V Ccmmissicn Expires
25
February 1. 1CCJ I
I ^**Hf^^ oauv oi U(M*» i
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KINGSBURY & ASSOCIATES, CERTIFIED SHORTHAND REPORTERS
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I I
rvj
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X
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j SEP-06-1994 10:01 DO-fiLC/EM HILL flFB UT 801 777 4306 P.002/602
OO-ALC/PAE June 2, 1994
7274 Wardleigh Road
Hill AFB UT 85056-5137
Ms. Peggy Bon
2485 East 7800 South
South Weber U84405
Dear Ms. Bon
As promised at the meeting last week, included is information on the groundwater contamination
that is migrating from Hill AFB into the South Weber valley.
Your home is not within the Operable Units at Hill. Although your daughter lives near Mr.
Brent Poll, her home is not in an Operable Unit or area of contamination. Mr. Poll owns some
land that Is over the plume, however, nothing was found at his home near your daughter.
We have added you and your daughter to our mailing list, so you will get information about work
being done in the South Weber area, also notices, newsletters, and other information.
Please let me know if you have questions or need more information. I hope you get involved in
the cleanup process. We need to hear from you.
Sincerely
GWEN BREWER
Environmental Public Affairs Coordinator
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JUN-01-1994 11:26 QQ-PLC/EM HILL fiFE UT 601 777 4306 P.003/e04
/" "S *
HILL AIR FORCE BASE
PUBLIC MEETING FOR PROPOSED PLAN
FOR OPERABLE UNIT 2
SOUTH WEBER ELEMENTARY SCHOOL
7:00 P.M., WEDNESDAY, 25 MAY, 1994
IF YOU WANT TO MAKE A COMMENT AND PREFER NOT TO SPEAK DURING
THE OPEN FORUM OR IF YOU THINK OF SOMETHING LATER, PLEASE COMPLETE
THIS FORM AND LEAVE IT TONIGHT OR MAIL IT BEFORE JUNE 1 1 , 1994, TO
OO-ALC/PAE, ATTN: GWEN BREWER, 7274 WARDLEiGH ROAD, HILL AFB UT
84056-5137.
YOUR NAME YOUR ADDRESS YOUR PHONE #
COMMENTS/QUESTIONS:
/MV FM.»r ^ A.^v^«». f& rry Ai-5^.^ .7.3
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JLN-01-1994 11:26
00-flLC/EM HILL flFB UT
E01 777 4306 P. 004/034
Comments Concerning Remedial Action OU2
Newspaper articles often cite the awards the HAFB Environmental
Directorate has earned concerning its programs to minimize the
production of new hazardous wastes, and for resolving problems
created before the Base became so responsible in this regard. Our
family has worked with these people for almost 30 years as we were
apparently the first to notice the off-base migration of pollution
from their toxic dump sites. We too agree that the professionals
in this Environmental office are now always approachable and seem
very capable.
Such expertise suggests that those with property polluted by the
Base should have the ideal advocate through which to have their
problems remedied. Hcwever, this is not the case. Although
budgets project that hundreds of millions of dollars are probably
needed to treat the problems created by the Base, not one dime has
been allocated to alleviate the property devaluations and related
problems of the residents hurt by the off-base migration of
contaminants, when questioned about this obvious disparity, the
highly acclaimed Environmentalists meekly say to file a claim with
the HAFB legal office.
No doubt the HAFB legal office is also staffed with able people;
but when confronted with such a claim, its role is adversarial.
They cite the Federal Torts Claim Act which precludes citizens from
obtaining damages except where negligence can be proven on the
government's part. Of course, they deny negligence and shift all
the burdens of proof onto those who claim injury. Federal legal
offices also infer that, as potential claimants, people are unwise
to place any trust or share any confidences with the Base's renown
Environmentalists. All involvement with them (including sign-in
rosters at their meetings) can potentially be used to refute claims
or disallow them entirely on a statute-of-1 imitation technicality.
In summary, we have found that the Base's efforts as a whole in
addressing its pollution problems are clearly more self-serving
than community oriented. Contrary to its claim, it was negligent
in placing most of its toxic wastes on the steep bluffs above South'
Weber where they could only migrate downward and off-base into
communities below. HAFB should appreciate that to ever deserve
credibility for its remedial plans, its Environmental and legal
offices must work together to find a way to genuinely safeguard its
neighbors and rectify the damages it has caused.
Brent Poll
South Weber
Landfill Coalition
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