&EPA
United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPAIRODIROB-921066
September 1992
PB93-964403
~
EPA Report Collection
L~oErmp~tioRn f!esource Center
. ,., ~'on 3
Philadelphia, PA 19107
Superfund
Record of Decision:
Hill Air Force Base, UT
Hazardous Waste Collectfon
lnformotton Resource Center '
US EPA Region 3 ..
PhUade'Phla, PA 19107
u . S. Environmental Protection Agen~
Region III Hazardous Waste
Technical Information Center
84 1 Chestnut Street, 9th Floor
Philadelphia, PA 19107
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NOTICE
The appendices listed In the Index that are not found In this dOcument have been removed at the request of
the issuing agency. They contain materiaJ whictt suwtement. but adds nofutther appIcabIe informatiOn to
the content of the document. All supplementai material is, however. contained In the administrative record
for this site.
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50272.101
REPORT DOCUMENTATION 11. REPORT NO. 1 ~ I. A8cIpIenI'. Acc888I8n No.
PAGE EPA/ROD/R08-92/066
4. 1118......... L A8part D8I8
SUPERFUND RECORD OF DECISION 09/25/92
Hill Air Force Base, UT ..
Second Remedial Action - Interim
7. AuIIor(.) .. P8rfonIIIng Qrg8nII8tIon .... No.
8. f'I8rfonIIq 0rpInIzd0n ..... ... Add!-. 10. PnIJ8dITII8IIIWCIItI UnIt No.
11. ConIr8ct(C)" Qrenl(G) No.
(C)
(Q)
1~ 1poI--. 0rpnIZ8IIan ..... ... Addr-. 11. Typ8" A8porIa PwrIod eo-.d
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. .... _...~ No...
PB93-964403
11. Ab8nc8 (\JIIII1: 2IID wanIe)
The 6,700-acre Hill Air Force Base (AFB) is located in north-central Utah, covering
portions of Davis and Weber Counties. Surrounding land use is predominantly
industrial. Shallow ground water in the area is used only for agricultural purposes,
and there are no wells that currently supply drinking water from the shallow aquifer.
This site is part of OU3 in the southeastern portion of the Base, which also includes
the Industrial Waste Treatment Plant (IWTP), sludge beds, Berman pond, ponds 1 and 3,
Buildings 510 and 514, and a contaminated ground water area. There are several areas
of the Base where past disposal practices and spills contaminated both the soil and
ground water. The Air Force has grouped geographically adjacent contaminated areas
into seven OUs. The Sodium Hydroxide Tank Site is a 29,000-square-foot area that
surrounds two 12,000-gallon underground storage tanks (USTs) constructed in the
1950's. The tanks, approximately 5 feet below the ground surface, are used to store
sodium hydroxide (NaOH) solution, which is used as an additive in wastewater treatment
at the IWTP. In 1980, an estimated 150,000 gallons of NaOH solution leaked from the
inlet cdnnections to the tanks over a l-year period. A second series of leaks
occurred in 1984, releasing approximately 132,000 gallons. Sampling investigations
(See Attached Page)
17. ~ An8Iy8I. L D88cr1pIol'II
Record of Decision - Hill Air Force Base, UT
Second Remedial Action - Interim
Contaminated Medium: gw
Key Contaminants: Organics
b. IcI8ntlft8r8/Op8n-EncI8cI T81'1118
c. COSA 11 Fl8ld/Group
18. Av8l11lbi1ity St8tem8nt 18. Seaaity CI... (ThI. Report) 21. No. of P.gee
None 34
20. Sec:t8'ity Ct... (Thl. Pege) 22. PrIce
None
See ANSl-Z38.18 See InalrUCliona on Reve- (4-77)
(ForrnetIy NTlS-35)
Depertnwnt of COIlllllllt'C8
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EPA/ROD/R08-92/066
Hill Air Force Base, UT
Second Remedial Action - Interim
Abstr.act (Continued)
and copper. In 1985, the state and C&D Recycling arranged for the excavation and offsite
revealed high soil pH and conductivities, indicating that most of the NaOH is probably at
a depth of 25 to 40 feet below surface. The presence of NaOH in ground water is
uncertain and will be investigated in future remedial investigations. A 1991 ROD
addressed the interim remediation of OU2 subsurface soil and ground water. This interim
ROD limits further degradation of ground water quality as a result of NaOH migration
through the unsaturated zone. Future RODs will address a final remedy for contaminated
soil and ground water at OU3 and other OUs at the Base. The primary contaminant of
concern affecting the soil is an organic, NaOH.
The selected interim remedial action for this site includes removing two underground
storage tanks; backfilling the excavated area with the previously excavated soil and
clean fill; and constructing a 29,000 square foot sloped temporary asphalt cap at the
ground surface after removal of the tanks to ensure drainage of precipitation into the
existing stormwater system. The tank removal project will be conducted under a state
permit and administered by the state under its Underground Storage Tank (UST) program,
under a state-issued permit, which will regulate decontamination and proper disposal of
the tanks and their associated piping, as well as testing for contamination of the native
soil underlying the .tanks and piping. The estimated present worth cost for this interim
remedial action is $55,343, which includes an annual O&M cost of $540 for 3 years.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific performance standards for this interim
action will be specified in the final ROD for all of OU3. This ROD invokes an ARAR
waiver on the basis that this is part of an interim remedy; therefore, RCRA closure
requirements will not be attained.
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t-
Hill Air Force Base, Utah
Record of Decision for Interim
Action at Operable Unit 3
Site ST04 .
September 1992
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RECORD OF DECISION FOR
INTERIM ACTION AT
OPERABLE UNIT 3
Site ST04 - Sodium Hydroxide Tank Site
Hill Air Force Base, Utah
. -,
September 1992
Prepared by:
Randal B. Klein, P .E.
w. Robert James, PhD, P.E.
Environmental Restoration Division
Environmental Management Directorate
Hill AFB, Utah 84056
(801 )777-8790
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1.0
1.1
1.2
1.3
'1.4
1.5
1.6
2.0
2.1 .
2.2
2.3
. 2.4
2.5
2.5.1
2.5.2
2.5.3
2.5.4
2.6
2.7
2.8
2.8.1
2.8.2
2.8.3
2.8.4
2.8.5
2.8.6
2.8.7
2.8.8
2.8.9
2.9
2.10
2.10.1
2.10.2
2.10.3 .
2.1 0.4
2.10.5
2.11
3.0
Table of Contents
. Declaration for the Record of Decision
Site Name and Location
Statement and Basis of Purpose
Assessment of the Site
Description of Selected Remedy
Statutory Determination
Signature and Support Agency Acceptance of the.
Remedy'
Decision Summary
Site Name, Location and Description
Site History and Enforcement Activities
Highlights of Community Participation
Scope and Role of Response Action'
Site Characteristics ..
Soils
Ground .Water .
Effect of NaOH on Mobility of Trace Metals
Current Status of Contaminant Migration
Summary of Site Risks .
Description of Alternatives
Summary of Comparative Analysis of Alternatives
Overall Protection of Human Health and the Environment
Compliance With ARARs . .
Long-term Effectiveness and Permanence
Reduction of Toxicity, Mobility or Volume Through
Treatment .
Short-term Effectiveness
Implementability
Cost
State/Support Agency Acceptance
Community Acceptance
Selected Remedy
Statutory Determinations
Protection of Human Health and the Environment
Compliance With ARARs .
Cost Effectiveness
Utilizaton of Permanent Solutions or Alternative
Treatment Technologies to the Maximum Extent
Practicable
Preference for Treatment as a Principal Element
Documentation of Significant Changes
Responsiveness Summary
1
1
1
1
1
3
4
5
5
5
7
8
8
9
9
16
16
17
18
19
19
20
22
22
22
23
23
24
24
24
25
25
26
26
26
27
27
27
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List of Figures
1 Operable Unit 3 Location Map 2
2 Sodium Hydroxide Tank Site 6
3 Cross Section A-A' Through the Sodium Hydroxide 1 1
Tank Site
4 Ground Water Countour Map, Sodium Hydroxide 12
Tank Site
List of Tables
1 Soil Sample and Initial Ground Water Analyses, 10
Sodium Hydroxide Tank Area
2 Summary of Ground Water Analyses, Sodium 14
Hydroxide Tank Site, Operable Unit 3
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1.0
DECLARATION FOR THE RECORD OF DECISION
, . ,
Site Name and Location
Operable Unit 3, ~'Sodium Hydroxide (NaOH) Tank Site, Hill Air Force Base
'(AFB), Davis and Weber Counties, Utah.
1.2
Statement of Basis and Purpose
This decision document presents the selected interim remedial action
for Operable Unit 3 (OU 3), developed by Hill AFB (the Base) 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 upon the contents of the Administrative Record
. for OU 3, Hill AFB. The US Environmental Protection Agency (EPA) and
the Utah Division of Environmental Response and Remediation (UDERR)
concur with the selected interim remedial action.
1.3
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if
not addressed by implementing the response action selected in this
Record of Decision (ROD), may present an imminent and substantial
endangerment to public health, welfare, or the environment.
1.4
Description of Selected Remedy
The Sodium Hydroxide Tank Site is located within au 3. OU 3 is located
in the southeastern portion of Hill AFB (Figure') and consists of the
Sodium Hydroxide Tank Site, the Industrial Waste Treatment Plant
(lWTP) Sludge Beds, Berman Pond, Pond " Pond 3, Buildings 510 and 514
(Refueling Vehicle Maintenance Facility), and a contaminated ground
water area in Layton. OU 3 is one of seven operable units defined for
response actions under. CERCLA. On-base areas surrounding au 3 are
dedicated to industrial uses related to servicing and. maintaining
aircraft. At this time, work is in progress to select final remedies for
the remainder of OU 3 and for the other operable units at Hill AFB.
The selected interim remedial action for the Sodium Hydroxide Tank Site
is a source control alternative for NaOH that consists of constructing a
temporary asphalt cap. The scope of this action is limited to
1
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...., .
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.... James M. Montgomery
ROY
SU~SET
CLINTON
CLEARFIELD
.
IIIR~ERD'LE/
~ OPE~.LE ". .
Ii- UNIT 6 \ -
k " (Bldg. 1915) .
84 If (Asphalt Pad)
It. 1\ Hill AFB Boundarv
~\ -
r /\ OPERABLE UNIT 4
.,~ (LandfiU #1)
I , (Landfill #2)
. . (North Gate Dump)
/
..
s
..
"'
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~
..
@
o
.s
OPERABLE UNIT 5
I (:ooele Army Rail Depot) f
H OPERABLE UNIT 4
W (Munitions Dump)
OPERABLE UNIT 2 .
(Chem Pit #3)
(Perimeter Road)
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.
I
.
\
.,OPERABLE UNIT 5
. (Bamberger Pond)
~
~
HILL .
AIR FORCE
BASE
" SOUTH
~ WEBER
"
. ,~OPERABLE UNIT 1
, . (Landfill #4)
(Chern Pit #1.2)
(Landfill #3)
(FI/'e Training Area)
o
0_.
PERABLE UNIT 7
(Bldgs. 220 and 225)
'J8 - .
1--\-'
. OPERABLE UNIT 1
I (Golf Course)
.
I
.
I
.
I
OPERABLE UNIT 3
(NaOH Spill) **
(Berman Pond)
(IWTP Sludge Beds)
(Layton Area)
(Pond 1)
(Bldg. 510.514)
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S~I'tU:"'1
,\YTO:-;
'\
\
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.RIHUi
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If
HILL AIR FORCE BASE
OPERABLE UNIT 3 LOCATION MAP
FIGURE 1
2
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contaminated soils. This action is expected to reduce the downward
migration of contaminants froin the soils to the underlying ground water,
which is the principal threat at this site. Remediation of t~e ground
water and final remediation of contaminated soils will be addressed in
the final ROD for OU 3.
This interim action does not affect the removal, testing and disposal of
the tan.ks themselves, or testing of soils directly beneath the tanks and
associated piping. The tank removal project will be regulated by UDERR
. pursuant to a permit issued by that agency. The final remedial action for
the Sodium Hydroxide Tank Site and any ground water contamination
from that site will be addressed as part of the cleanup plan for all of OU
3. .
1.5
Statutory Determination
The interim action is protective of human health and the environment and
. is cost effective. A waiver can be justified for whatever Federal and
State applicable or relevant and appropriate requirements (ARARs) that
will not be met. This action is interim and is not intended to utilize.
permanent solutions and alternative treatment (or resource recovery)
technologies to the maximum extent practicable for .this operable unit.
Because this action does not constitute the final remedy for the oper~ble
unit, the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element will be
. addressed by the final response action. Subsequent actions are planned
to address fully the principal threats posed by this operable unit.
Because this remedy will result. in hazardous substances remaining on
site above health-based levels, a review will be conducted to ensure that
the remedy continues to provide adequate protection of human health and
. the environment. within five years after commencement of the remedial
action. Because this is an interim action ROD, review of this site and of
this remedy will be continuing as the Air Force continues to develop
final remedial alternatives for the operable unit.
3
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Signature ~nd Support Agency Acceptance of the.
Remedy
Lef!:!!i6 ~
Brigadier General, USAF
Vice Commander
, .6
. J SEP 1992
Date
ck W" McGraw
cting .Regional Administrator
US vionmenal Protection Agency Region VIII
~0'L
ate
_0.
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Date
. Kenneth L. Alkema.
. Executive Director
Utah Department of Environmental Quality
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2.0
DECISION SUMMARY
2.1
Site Name, Location and Description
Hill AFB is located in north-central Utah, covering portions of Davis and
Weber Counties. The Base is topographically situated on a plateau
formed by the ancient Weber Delta and is approximately 300 feet above
. the adjacent Great Salt Lake Basin. Land surrounding..the Base slopes
westward toward the basin. .
The Sodium Hydroxide Tank Site is located in the southeastern quadrant
of Hill AFB, and its location is shown in Figure 1 (as the NaOH spill).
This portion of Hill AFB is an industrial area and is used for servicing
and maintaining aircraft. The area surround.ing the Sodium Hydroxide
Tank Site is generally flat, well-drained, and covered by industrial'
facilities, parking lots, and roadways. The closest off base land uses are
commercial and residential, at a distance.. of approximately 2000-3000
feet from the Sodium Hydroxide Tank Site. The closest use of natural
resources is agriculture, at a distance of approximately 2000-3000 feet
from the Sodium Hydroxide Tank Site. The estimated population of the.
two square miles of the Layton area that lies to the south of Hill AFB
(closest to the site) is 2500 residents. .
The Sodium Hydroxide Tank Site consists of an approximate 29,000
square foot area that surrounds two 12,000-galion underground storage
tanks constructed in the 1950s (Figure 2). The tanks are estimated to be
approximately five feet below the ground surface and have a diameter of
about 10 feet. The tanks are used to store a 25 percent by weight
sodium hydroxide NaOH solution, which 'is used as an additive in the
treatment of wastewaters .at the IWTP.
The near surface soils beneath the Sodium Hydroxide Tank Site are
mainly sands and gravels. The water table is at an approximate depth of
78 feet below the ground surface. Shallow ground water in the area is
used for agricultural purposes, mainly irrigation and stock watering.
Ground water in this area is also intercepted by field drains to lower the
water table for off-Base residential and industrial development. Based
on a water rights survey, there are no wells that currently supply
drinking water from the shallow aquifer. The drinking water for local
residents is taken from aquifers that lie several hundred feet beneath
the ground surface at OU 3. .
2.2
Site History and Enforcement Activities'
In 1987, Hill AFB was listed on EPA's National Priorities List for
5
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ESE-P1
....... James M. Mon\gomery
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EX\'LANATION
o
Monitoring woll
. Soil Boring
A A' Location 01 cross secllon
.l-j shown In Figure 2.3
DBT-1 .
5'::-1 5HA-2
.
II
JIM.'~ )J
SODIUM
HYDROXIDE
TANKS
@DBT-2
. DE-3
@ DE-2
@ DE-1
u
ESE-B14 ...
@JMM-1
5HA-3
.
5HA-1
a
.'
«::» Industrial Waste
O Treatment Plant
o Cblplex
o
o ~ DE..
@JMM-2
;.
.100 .'
. . .. I
Scale In Fect
HILL AIR FORCE BASE
SODIUM HYDROXIDE
TANK SITE
FIGURE'. 2'
. .0
I
WEST SLUDGE
. BEDS
EAST SLUDGE @ DE-S
BEDS
DBA-1.
@
DE-6
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environmental cleanup. au 3 is one of seven operable units for which
remediation will occur at Hill AFB. The Sodium Hydroxide Tank Site was
originally included in au 3 as a result of concern arising from historic
releases of NaOH from the tanks.
Investigations of the Sodium Hydroxide Tank Site included a site
characterization investigation (1988 and prior) and a remedial
investigation (begun in 1989). During these efforts, ;,four soil borings
were constructed, sampled, and analyzed for alkalinity, hydroxide,
carbonate, and bicarbonate. Three wells were installed and analyzed for
Volatile Organic Compounds (VOCs), metals, and major ions. .
In April, 1991, Hill AFB entered into a Federal Facility Agreement (FFA)
with EPA and UDERR according to CERCLA Section 120. The interim
remedial action at the Sodium Hydroxide Tank Site is being selected,
designed .and implemented according to the requirements of the FFA,
under which the US Air Force is the lead agency.
2.3
Highlights of Community Participation
Community participation requirements in CERCLA Sections 113 (k) (2)
. (B) (i-v) and 117 have been met for this interim action. An
Administrative Record has been established that contains all of the
information that forms the basis of this response action. Hill AFB has an
approved Community Relations Plan that is updated every six months.
The Proposed Plan for Interim Action and companion documents were
released to the public in January, 1992. All of these documents were
made available in both the Administrative Record at Hill AFB and the
Davis County Library-Central Branch in Layton. Newsletter articles and
the final proposed plan were mailed to approximately 300 individuals
and organizations on the Hill AFB mailing list. Full public participation
and comment were requested as part of issuance of the proposed plan.
Display advertisements announcing the public comment period and public
meeting were published in the Ogden Standard Examiner and the Salt Lake
Tribune on January 30 and 31, 1992. News releases announcing the same
were sent to these newspapers, and to local radio stations and television
stations on January 30, 1992.
A public comment period was held from 30 January 1992 through 2 March
1992. A public meeting was held on 13 February 1992 to present the
results of and to solicit public comments on the Focused Remedial
InvestigationfFeasiblity Study (RifFS) and the alternatives as presented.
in the Proposed Plan for the operable unit. The meeting was held at the
Davis County Library-Central Branch in Layton. Additional copies of the
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Proposed Plan and fact sheets describing the Installation Restoration
Program (IRP), its history and the history of the base were made
available to the public at the public meeting. .
2.4
Scope and Role of Response Action
Hill AFB covers 6,700 acres, and has several areas where. past disposal
practices and spills have contaminated- soil and ground,-water. Because
the Base covers a large area, the Air Force decided to group
geographically adjacent contaminated areas into operable units, each to
be addressed under separate but concurrent investigations. au 3, part of
which is the subject of this Record of Decision for Interim Action, is one
of seven operable units under investigation at Hill AFB.
The primary interim action objective for the Sodium Hydroxide Tank Site
is to reduce the potential for degradation of ground water quality as a
result of migration of NaOH through the uQsaturated zone. If the interim
action is not accomplished, no action would be taken at the site for an
additional two or more years, and ground water quality could be
degraded. Remediation of ground water contamination is not an
- objective of this interim action. Subsequent actions to be taken in the-
vicinity of the Sodium Hydroxide Tank Site will address ground water
contamination. for this site, as well as for the remainder of au 3.
When the ROD is finalized for all of au 3, additional remedies may be
required for the unsaturated soils at the Sodium Hydroxide Tank Site.
The interim action will be consistent with any planned future actions to
the extent possible. .
2.5
Site
Characteristics
It is believed that around 1980, during an upgrading of the IWTP, an
estimated 150,000 gallons of NaOH solution leaked from the inlet
connections to the tanks over a one-year period. Because the plant
continued transitional operation during the upgrade, the leak was not
immediately detected. A second series of leaks totaling approximately
132,000 gallons was reported to have occurred from about April to June,
1984. The concentration of the NaOH solution was 25 percent by weight.
These are the only .known sources of contamination at the Sodium
Hydroxide Tank Site.
The NaOH solution is relatively mobile in the subsurface and moves
through the unsaturated soil by gravity drainage. NaOH is not a known or
suspected human carcinogen. Direct dermal or inhalation exposure to
concentrated sodium hydroxide may cause temporary irritant effects.
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Any effect to drinking water would be .in the form of increased pH and
increased sodium concentrations. Sodium and hydroxide are not
bioaccumulated or biomagnified, and sodium is a normal dietary mineral
that is excreted rapidly from the body.
As stated in section. 2.1, the estimated population of the two square
miles of the Layton area that lies to the south of Hill AFB (closest to the
site) is 2500 residents, and shallow ground water in th~. area is used for
agricultural purposes, mainly irrigation and stock watering.
2.5.1
Soils
Data for pH, alkalinity, and conductivity from soil borings (Table 1)
indicates that some NaOH has migrated through the soils to a depth of
approximately 75 feet beneath the site and spread out to a width of
. about 170 feet as depicted in Figure 3. However, high soil pH and
conductivities indicate that most of the N.aOH is probably at a depth of.
25 to 40 feet below ground surface.
2.5.2
Ground Water
The near surface soils beneath the Sodium Hydroxide Tank Site are
formed from the sands and gravels of the Provo Formation. These
sediments are lacustrine in origin and were deposited in the ancient Lake
Bonneville. A schematic east to west cross section drawn through the
site is depicted in Figure 3. Logs from borings drilled near the tank site
indicate that the sediments are primarily interbedded sands and silty
sands with some clayey sands in discontinuous layers. Laboratory
measurements of permeability for samples JMM- 1 and JMM-4 indicated
vertical permeabilities from about 10-3 to 10-7 centimeters per second
(em/see). The log from soil boring ESE-P1, located approximately 450
feet west of. the site, indicates the presence. of a silt and clay layer at a
depth of about 135 feet. As shown in Figure 3, the lateral continuity of
the layer is uncertain, so it is difficult to predict whether the layer
extends eastward beneath the Sodium Hydroxide Tank Site.
Shallow unconfined ground water exists in the Provo Formation
sediments beneath the site. The water table is at an approximate depth
of 78 feet below the ground surface (Figure 3). Sediments in this unit
are presumably saturated .down to the level of the silt and clay layer at a
depth of about 135 feet below the ground surface. Figure 4 illustrates
the shallow ground water surface (water table) and indicates. that
shallow ground water generally flows toward the northwest in the
immediate vicinity of the Sodium Hydroxide Tank Site. At greater
. distances from the site, flow directions appear to change. The likeliest
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1'AUU:; I
SOli. SAMPlE AND INITIAl. anOUNDWATEIl ANALYSES
SODIUM IIYDROXIDE TANK AREA
811A.l 811A.2 BIIA.a 8111'-1'
f){ph Total Tolol Total 1'0141
(tuft bdow Alkalinity Conductivity Alkalinity Conductivity Alkallnlly ec.,cJuctlvlly AlltalIn Ily Cc..ulucUvlty
JrOUnd lonl) (milL) 1>11 (JllDh08lcm) (mi'l.) "1 (JUDh08lcm) (milL) .... (lUDhoelcm) (milL) ...1 (Iunhoalcm)
6.6.6 NA 7.8 S40 NA 8.2 fm NA NA NA NA 6.7 610'.
la-n.6 NA 9.'1 4~ NA NA NA NA 6.2 400 NA 6.7 &10
16-16.6 1,000 9.6 88} NA 1.9 610 NA NA NA NA '1.0 650
2()'21.6 l,Im 10.7 U)} 1,100 8.S 1m c.O .1.0 em 1,160 '1.4 600
26-26.6 62,000 >12 >10,000 Z!,OOO 11.0 > 10,000 NA '1.0 fiX) tro 8.9 1,000
28-28.6 NA NA NA 110,000 NA NA NA NA NA NA NA NA
3().9U 11,000 11.0 >1,000 43,000 11.6 >10,000 9,100 10.8 >10,000 '13,000 10.2. > 10,000. .
36-96.6 '1,:01 8.'1 4~ 13,000 10.9 >10,000 9:0 7.9 8X) NA 10.0 >10,000
4().41.6 NA 8.0 IiOO 2,000 >12 > 1 0,000 NA 1.4 1m fi,f.so 10.0 >10,000
46-46.6 . NA 8.2 8If) NA NA NA NA NA NA NA 8.6 1.600
6()'61.6 8.600 8.2 &JO NA NA NA l8,nOO 7.3 80 NA NA NA
66-66.6 NA '1.8 4'10 NA 9.8 610 NA NA NA :l.b'10 8.9 1,0011 ..
6().61.6 NA '1.9 400 NA NA NA NA 7.9 '1'10 8,490 NA NA
66.66.6 NA '1.8 &JO NA 8.3 6:D NA '1.0 rm NA 8.1 mo
'10. '1U 2. 600- '1.'1- 7~- 14,1100 10.2 4,600 I. II)()- '1.1- 640. NA 8.8 I,:nl
'16.'16.6 NA NA NA 6:100- 8.6- 280- NA NA NA NA- 8.1. 610.
f-' 8().81.6 NA NA NA NA NA NA NA NA NA NA '1.8 tnO
o
Groundwal.cr NA !t." Tn NA 9.0 1,000 NA '1.8 1.000 NA 8.3 910
Simple
- First uturoted 80ilumple
.-
NA & Not InllYlcd
Nolc: "II and cllnductivily mcasurementl were laken In the field
Source: Rodlln (1988)
-------
PRO"LCT NO,
..:.c::UU,UIVI
WEST
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:2
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o
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E
o
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b
CD
'C
CD
4700 ~
-'
tu
w
LL
~
Z
o
4600 ~
>
W
..J
W
o 50 100
I . I
Se81eln Feet
4500
4800
~
:t
V)
t-'
t-'
o
>
~ 4700
I-
w
w
~
~.
Z
o
~ 4600
>
w
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W
4500
EXPLANATION
" ,"; I Sand and silly sand with some
,..,.'. clayoy sand .
~ Clay and sHt
Water level
. NaOH contamlnatod 50115 ~ (measured 5/91)
NGVD Nallonal Geodellc Verllcal Datum (1929)
HILL AIR FORCE BASE.
CROSS SECTION A-A' THROUGH
SODIUM HYDROXIDE TANK SITE
FIGURE 3
JMI James M. Monlgomery
.
-------
.@~\
..
o
1000
EXPLANATION
"-
c
c
cO
c
~
ci
z
~
<.)
I.U
-,
o
a:
a..
ESE.2 <:) Monitoring well installed lor au 3 and Layton Remedial
Investigations .
APT.7. Monitoring well installed lor other investigations
"
- 4690 Groundwater Elevation (Ieet) contour interval. 10 leet
JMiI James M. Montgomery
Water level elevation. leet above MSL (measured
.(<4696) May 1991): < indicates dry well. water level elevauon
is lower than that 01 the bottom of the well screen
~ Former pond site: presently capped or filled
HILL AIR FORCE BASE
GROUNDWATER CONTOUR MAP
SODIUM HYDROXIDE TANK SITE
FIGURE 4
.
12
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flow direction would be westerly with northern or southern flow
components to conform to regional flow directions. Figure 4 also shows
a ground water divide in the vicinity of au 3, south of the Sodium
Hydroxide Tank Site. Ground water south of this divide flows to the
southwest and off-Base. Seeps and springs occur locally in thjs area,
probably where the tops of clay layers intersect the ground surface.
,Some of these springs are used for agricultural purposes, mainly
irrigation and stock watering. Ground water in this area is also
intercepted by field drains to lower the water table for off-Base
. residential and industrial development. .
Based on a water rights survey, there are no wells that currently supply
drinking water from the shallow aquifer. The ambient water quality is
marginally suited for domestic use, and the yield from the aquifer is
usually low. .
The Sunset and Delta aquifers lie several hundred feet beneath the,
ground surface at OU 3. The Sunset Aquifer is composed of sands and
gravels and silty, clayey sands and gravels, and ranges in thickness from
50 to 250 feet. The nature and thickness of the Sunset varies laterally
, and it' thins out considerably in the central portion of Hill AFB. A'
200-foot thick aquitard composed of fine-grained silty sand and clay
separates the Sunset from the underlying Delta Aquifer. The Delta is the
more productive of the two aquifers. It is composed of coarse sands,
gravels, and boulders and its thickness ranges from 200 to over 300 feet
. thick. Both the Sunset and Delta aquifers are used' as water supply
sources in the vicinity of Hill AFB.
Analyses of ground water samples eollected from soil borings SHA-1,
SHA-2, SHA-3, and SHT -1 indicate that the shallow ground water has
elevated pH values of greater that 9 in borings SHA-1 and SHA-2, and
slightly elevated conductivities of greater that 1,000 micro mhos per
centimeter (J.lmhos/cm) in borings SHA-2 and SHA-3 at the time the soil
borings were drilled (Table 1). However, ground water samples collected
from the monitoring well' constructed in boring SHT -1 did not yield
elevated pH or conductivity (Table 2). The reason for this difference is
unclear, although it is possible that the ground water samples collected
from soil borings SHA-l, SHA-2 and SHA-3 were contaminated from
. above by NaOH contaminated soils. It should be noted that these samples
were taken while drilling the soil borings and were not from a developed
monitoring well. Three ground water samples collected from JMM-1 and
four collected from JMM-4 do not contain elevated pH or sodium values,
nor do the data show any increasing trends (Table 2).
Although no elevated sodium concentrations or pH levels were observed
13
-------
SUMMARY OF GROUNDWATER ANALYSES.
SODIUM IIYDJtOXIDE TANK bTI'E, OPERABLE UNrf:J
PntenUnJ Sample Names: SlIT. 1 SIIT.l SlIT. 1 JMM.l ' JMM-l JMM.I JMM~ JMM~ JMM-4. JMM~
ARAR note: IOn/a8 11112/80 t.'28f88 9I3~8tI 014100 10120100 eJ23I88 2/18/89 5130100 1000MMI
Jon Analvsls ImlflL)
Sodium NE NA NA. 23.4 12.6 12.1 11.9 14.5 22.2 17.0 16.9
PoLaulum NE NA NA 2.1 3.1 3.5 3.9 4.9 42.15 9.0 8.5
Calcium NE NA NA 92.6 106 83.9 107 137 l300 153 11)4
Magnesium NE NA NA 19.4 21.5 21.2 22.6 . 30.6 244 38.2 3U
BlcarbonaLe NE 370 ZD 353 40'2 33-. :m 679 NA (DI 511
Csrbonale NE NO ND 0.61 0.44 0.58 0.66 0.5 NA O.M 0.56
Chloride NE NA NA 17 15 9.8 8.71 12 NA 5.9 5.81
Sulfate 4001500 PMCL, NA NA 3S 15 16.2 18.6 17 NA 18.6 17.46
l000UMCL
Nitrale 10 MCL NA NA . 3.4 6.3 0.51 7.11 6.1 NA 7.3 7.71
lIydrolldo Nt,; ND ND 0 0 () 0 0 NA 0 0
pH 6.5.85 GWQS NA NA 7.6 7.4 7.0 7.6 7.3 NA 7.5 7.4
Conductivity NE NA NA 675 735 610 ?DO roo NA !m 1~
Alkalinity (totol) NE 370 ZO 200 :m 275 310' 475 NA fm 4m
I-' TDS 2IJOO UMCL NA NA 3«11 :m 3R4 414 rm NA 674 001
l>o Hard non NE NA NA 313 3.')5 2)9 362 470 NA 6-12 411
Yol111lln Onrnnlc Comnounda h.ltJU
1,1- Dichloroclhane NE NA NA 2.1 <0.10 <11.511 <0.50 0.5 0.4li7 <1.25 <12.5. ~
l,l-Dlchloroethene 7.0 MCL NA HI. a <0.10 <0.50 <0.60 0.4 1.02 4.1 ill
Tetrachloroethene 5.0 MCL NA HI. d.O <0.10 <0.00 <0.50 1.0 1.48 <1.25 <12.5
.1,I,I-Trichloroethane 200 MCL NA HI. &I 0.7 0.8 <0.60 3.6 7.53 11 100
Trichloroethene 5.0 MCL NA HI. .18 4.4 5.1 1.3 1.0 1.27 11 a1
1rnco MollllH hnlflL)
Aluminum NE NA NA NA NA NA NA NA' 221 NA NA
Anllmony 0.01 PMCt. NA NA NA NA NA NA NA Q.Da:i NA HI.
Anenlc n.05 MCt. NA NA NA NA NA NA NA o.ama.NA NA
Barium 2 PMCL, NA NA 0.2 0.75 O.7ti 0.73 0.83 U6 O.li6 0.80
UMC1.
lIurylllum o.nO) I'Mel. NA NA NA NA NA NA NA U.Dl NA NA
Dornn NE NA NA NA NA NA NA NA NA NA NA
/'
Nolo: Seo loal pogo of whle for nbhreviallon definlliona.
-------
1.. ~E 2
SUMMARY OF GROUNDWATER ANALYSES
SODIUM IIYDIlOXIDE TANK srrE, OPEnAnLE UNIT 3
(CONTINUED)
Potentia] Sample Names: SIlT-I 811T.1 8HT-l JMM.l JMM.l JMM.l JMM-4 JMM-4 JMM-4 JMM-4
ARAR Dnte: 10n/88 11/12/88 DI28I88 0130.'88 0/4/00 10/21)J00 9123188 2/10/89 5fJOJOO 10130100
Tract Metnls lmldL) lcon'U
Cadmium 0.005 PMCL, NA NA <0.003 <0.003 <0.005 <0.005 <0.003 <0.003 <0.005 <0.005
0.01 MCL
Chromium 0.1 PMCL, NA NA D.11 <0.014 <0.10 .<0.10 0.015' o.m <0.10 <0.10
0.05 MCL
Cobalt NE NA NA NA NA NA NA NA 0.145 NA NA
Copper 1.0 UMCL .NA . NA NA NA NA NA NA 0.269 NA NA
Cyanide 0.2 PMCL NA NA NA NA <0.005 <0.005 NA NA <0.005 <0.016
Iron NE NA NA <0.020 <0.020 NA NA <0.020 278 NA NA
Lead 0.05 MCL NA NA <0.002 <0.002 0.003 <0.002 <0.002 2.lSf1 <0.002 . <0.002..
Manganese NE NA NA NA NA NA NA NA 7.45 NA NA
Mercury 0.002 MC). NA NA <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 0.001 <0.0002 <0.0002
Nickel 0.1 PMCL NA NA NA NA NA NA NA Q.288 NA NA
Selenium 0.05 PMCL, NA NA NA NA NA NA NA <0.005 NA NA
...... 0.01 MCL
VI
Silver 0.05 MCL NA NA NA NA NA NA NA <0.010 NA NA
Thallium 0.002 PMCL NA NA NA NA NA NA 'NA <0.005 NA NA
Vanadium NE NA NA NA NA NA NA NA 0.53 NA NA
Zinc NE NA NA NA NA NA NA NA 0.974 NA NA
Notes:
Concentrations that exceed a standard ore underlined
NA Not analyzed
ND Not detected
NE Not eatablished
MCL Maximum contamin/lnt level
PMCL Propo/led mnlimum contaminant level
UMCL Utah maximum contaminant level
GWQS Groundwater Quality Stand/lrds listed in the Utah Groundwater Quality Protection RcgulaUons (R448-6-2)
< Not detected (below detection limit shown)
-------
in wells SHT -', JMM-', and JMM-4, several VOCs and metals were
detected at concentrations exceeding maximum contaminant levels
(MCLs). For example, as listed in Table 2, 1,1 -dichloroethene (30
micrograms per liter Wg/ID and trichloroethene (20~gll) were measured
in the samples collected in October 1990 from JMM-4. The MCLs for
these chemicals are 7 pg/I and 5 ~g/I, respectively. Concentrations
.exceeding MCLs of several metals including antimony, arsenic, barium,
chromium, lead, and nickel were measured in sample.s collected from
JMM-4 in February 1989 (Table 2).
The presence of NaOH in ground water is uncertain because 1) initial
ground water samples taken from saturated sOils during the soil boring
process may have been contaminated from overlying materials, and 2)
nearby wells have not shown the presence of NaOH contamination.
VOCs and metals are not contaminants of. concern for this interim action.
Other contaminated sites in the immedi;ite vicinity could explain the
: detection of VOCs and metals in the ground water near the tanks. The
presence of these compounds is not believed to be related to the NaOH
leaks. The NaOH tanks have never contained VOCs or soluble metals.
. Although some of the metals could have leached from soils impacted by
the NaOH release, the source of the VOCS is probably. not this site. This
apparent ground water contamination by VOCs and metals does not
influence the selection of the interim alternatives considered in this
document; it will be evaluated fully in the RI/FS for all of OU 3.
2.5.3
Effect 0., NaOH on Mobility of Trace Metals
The introduction of a strong base such as NaOH to the soil column could
lead to the mobilization of base-soluble trace metals of major cations,
such as arsenic and selenium. Therefore, it is possible that the release
of NaOH to soils at this site could lead to increases in other cations
besides sodium,. such as calcium and potassium, as well as trace
metalloids (eg., arsenic and selenium) in the shallow ground water.
2.5.4
Current Status of Contaminant Migration
As the NaOH was released from the tanks, it migrated horizontally and
vertically through the soil along paths of least resistance dictated by
lithologic variations of the subsurface sediments. The migration through
the soil probably occurred under saturated conditions until the bulk of
. the release was bound up by capillary forces in the pore space of the
soils. Analytical data indicate that the NaOH migrated vertically until
finer-grained clayey sands were encountered at a depth of approximately
30 feet. At that point, the NaOH apparently spread laterally for a radial
16
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distance of approximately 85 feet (Figure 4). In some areas, the NaOH
may hav.e followed preferential flow pathways where clay lenses are.
discontinuous or non-existent in the subsurface. This condition is'
suggested based on analytical data, which indicate the NaOH 'may have
reached the water table in localized areas. At the time of the sampling,
the. majority of'the contaminant mass was at a depth of 25-40 feet.
2.6
Summary of Site Risks
Hill AFB analyzed samples from the soils and ground water in the
vicinity of the Sodium Hydroxide Tank Site. Population statistics and
social practices were also examined to evaluate the likelihood that
people would be exposed to contamination. This interim' ROD will
address risks from the Sodium Hydroxide Tank Site in a qualitative
fashion. The forthcoming Baseline Risk Assessment for OU 3 will fully
evaluate the effects of contamination (for the Sodium Hydroxide Tank
Site and for all of OU 3) on Hill AFB employees, residents, and off-base
residents.
One threat from conditions at the tank site is inhalation of and direct
dermal' (skin) exposure to NaOH when the tanks are removed. Inhalation
of NaOH from contaminated dust or powdered chemical may cause
irritation to the lungs and vascular pathways with prolonged exposure.
Dermal exposure could result in the development of a skin rash or a mild
chemical burn. These are both short-term effects. It is unlikely that
any long-term effects would result from these exposures. Personal
protective equipment will be provided as necessary during construction
activities to protect workers. Strict engineering controls will also be
used to protect workers and the public. During construction activities,
access to the site will be restricted. .
Currently, shallow ground water in the vicinity of Hill AFB is used for
stock watering and irrigation. Municipal water is used to supply
residences in this area. Consequently, there are no current ground water
pathways for human exposure. As stated in section 2.5, sodium and
hydroxide are not bioaccumulated or biomagnified, and sodium is a
normal di.etary mineral that is excreted rapidly from the body. In the
long-term, ground water containing NaOH could be consumed by nearby
residents in the future. Water quality in the shallow aquifer may be
degraded as a result of an increase in pH (from hydroxide ions), total
dissolved solids (TDS), and sodium concentrations. It is unknown
whether water quality in the shallow aquifer would be degraded below
drinking water standards.
,Environmental risks from the tank site are minimal.
There are no
17
-------
critical habitats or endangered species in the area affected by the
Sodium Hydroxide Tank Site. No biota are known to have been affected by
the Sodium Hydroxide Tank Site to this point in time.
Actual or threatened releas!s of hazardous substances' from the tank
. site, if not addressed by the selected alternative, may present a current
'or potential threat to public health, welfare, or the environment. The
. interim action is expected to stabilize the site and;" prevent further
environmental degradation by reducing the downward migration of
contaminants to the ground water~ If no action is taken to address the
threat of ground water contamination until final remedial alternatives
are evaulated, ground water quality may be degraded.
2.7
. Description of Alternatives
The R! 'FS report and Proposed Plan evaluated two alternatives for an
interirr, action to address' human health. and environmental problems
caused by NaOH. Both of these alternatives are summarized in this
section. Neither alternative is necessarily expected to be a final remedy
for conditions at the tank site. The final remedial alternative, . which
will be developed in accordance with the results of the Baseline Risk
Assessment and remedies of all of OU 3, will require additional data
collection and/or remedial actions to be undertaken at the Sodium
Hydroxide Tank Site.
The first. alternative for interim action consisted of maintaining
existing tank site conditions after removal of the two tanks, and
backfilling the excavations with the excavated soil and additional clean
fill. No effort would be made to remediate the soil until a final remedial
action is selected in the ROD for all of OU 3. This alternative would not
incur any costs in the short term (tank removal will occur regardless of
the chosen alternative). However, final cleanup costs might be increased
if the contaminants have in the interim migrated further into the soils
below the currently contaminated zone. The capital cost to implement
the first alternative is $0. Annual operation and maintenance cost is $0.
The 3 year present worth cost is $0. The time to implement the first
alternative is 0 months. .
For the selected interim action alternative, in addition to the details
mentioned for the first alternative, a temporary cap will be constructed
at the ground surface after removal of the tanks and backfilling the
excavation. An area of approximately 29,000 square feet (170 feet by
170 feet) will be capped to cover the apparent lateral extent of the NaOH
plume in the soil beneath the tanks. Constructed from asphalt overlying
a granular base, the temporary cap will be sloped to ensure drainage of
18
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precipitation into the existing stormwater system. The capital cost. to
implement the selected interim alternative is estimated to be $54,000.
Annual operation and maintenance cost is estimated to be $540. The 3
year present worth cost is $55,343. The time to implement the selected
interim alternative is estimated to be 1-4 months.
'Neither alternative VJiII involve excavation or treatment of contmainated
materials. Since the site is currently in an industrial.. area, threre will
be no adverse physical effect to the environment from either alternative.
Information on compliance with ARARs is contained in section 2.8.2.
The tank removal project will be, administered by UDERR via its
Underground Storage Tank (UST) rules. All related UST activities will be
conducted pursuant to a permit issued by UDERR. The permit issued by
UDERR will regulate decontamination and proper disposal of the NaOH
tanks and their associated piping, as well as. testing (for contamination)
of the native soils underlying the tanks. and their associated piping..
Personal protective equipment will be provided as necessary during
construction activities to protect workers. Strict engineering controls
will also be used to protect workers and the public. During construction.
activities, access to the site will be restricted.
2.8
Summary of Comparative Analysis of Alternatives
Provisions of the NCP require alternatives to be evaluated against nine
criteria in the Code of Federal Regulations (CFR) (40 CFR Part 300). Each
interim action alternative is evaluated against each of these nine
criteria and then against each other to identify a selected alternative.
The extent of the evaluation against these criteria is limited to the
intended scope of the interim action. These criteria are described in the
following subsections:
2.8.1
Criterion 1: Overall Protection of Human Health
and the Environment
Protectiveness is the primary requirement that remedial actions must
meet. A remedy is protective if it adequately eliminates, reduces, or
controls all current and. potential risks' posed through each pathway by
the site. The assessment against this criterion describes how. the
alternative, as a whole,. achieves and maintains protection of human
health and the environment.
The first alternative limits human dermal and inhalation exposures to
potentially contaminated soil removed in the UST action by placing it
into the bottom of the excavation and then covering it with clean soil.
19
,
-------
This alternative is not considered protective of human health and the
. environment overall because the mobility of contaminants is not reduced.
As stated in section 2.6, it is unknown whether water quality in the
shallow aquifer would be degraded below drinking water standards~
. Capping of the' site also limits human dermal and inhalation exposures to
.potentially contaminated soil. In addition, capping will provide an
impermeable surface preventing precipitation from ~oving downward,
thereby leaching NaOH from contaminated soils. The rate at which NaOH
migrates downward to the water table will be minimized and the volume
of leachate generated will be reduced. It is. unknown whether water
quality in the shallow aquifer would be degraded below drinking water
standards under the selected alternative. However, protection against
significant degradation of water quality in the' shallow aquifer is
greater under the selected alternative.
2.8.2
Criterion 2: Compliance with., ARARs
ARARs are applicable or relevant ,and appropriate requirements.
Applicable requirements are cleanup standards, standards of control, and
. other substantive environmental protection requirements, criteria, or
limitations promulgated under Federal or State law that specifically
address a hazardous substance, pollutant, contaminant, remedial action,
location or other circumstance at a CERCLA site. Relevant and
. appropriate requirements address problems or situations sufficiently
similar to those encountered at the CERCLA site that their use is well
suited to the environmental and technical factors at a particular site.
ARARs are grouped into three categories: .
.
Contaminant-specific ARARs are health or risk based numerical
values or methodologies that, when applied to site-specific
conditions, result in the establishment of the amount or
concentration of a chemical that may be found in, or discharged to
the environment (soil, water, or air). .
.
Location-specific ARARs restrict the concentration of hazardous
substances or the conduct of activities solely because they are in
specific . locations, . such as flood plains, wetlands, historic places,
and sensitive ecosystems or habitats. .
.
Action-specific ARARs are usually technology or activity-based
requirements or limitations on actions taken with respect to
hazardous wastes. The largest number of action-specific
requirements are generally provided by the Resource Conservation
and Recovery Act (RCRA) and its amendments.
20
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The analysis of ARARs has been limited to the scope of the interim
action. Other ARARs. may be involved in implementing. the final.
remedy(ies).
No contaminant-specific ARARs exist for NaOH in. soils. Potential ground
'water chemical-specific ARARs will. be addressed in evaluating final
remedial alternatives for OU 3. No location-specific ARARs have been.
identified. The site is not located within a 100-year flood plain,
wetland, historical site, or sensitive ecosystem or habitat. .
The no-action alternative postpones meeting ARARs until the final
remedy(ies) are implemented. Containment by capping represents. a
preliminary step in achieving action-specific ARARs for the soils.
Federal (40 CFR Part 264 Subpart J and 40 CFR Part 280) and State (Rule
R450-8- 10) requirements related to the re.moval and disposal of the tank
system will be complied with by meeting conditions of the permit for
.removal of the underground storage tank$ used to store NaOH.
Action-specific ARARs that will be met include:
.
. Dusty conditions during cap construction will . require fugitive dust
and fugitive emissions to be controlled through the best available
technology under Utah Administrative Code (U.A.C.) R31 7- 1 -4 and
the Clean Air Act (40 CFR Part SO).
.
U.A.C. 450-101.3 requires removal or control of the source. This
action provides source control until final remedies are
implemented.
The selected remedy does not attain the RCRA closure requirements of
Rule R450-8- 14, U.A.C. (40 CFR Part 264, Subpart G). This ROD invokes a
waiver of those ARARs under CERCLA Section 121 (d) (4) (A) on the basis
that this remedy is part of an interim remedial action. Compliance with
the closure requirements is inappropriate at this time because the
purpose of the temporary cap is only to stabilize the site until final
remedial alternatives for. OU 3 can be evaluated.
ARARs will be evaluated and re-evaluated throughout the RifFS process
for OU 3. The final remedial action for OU 3 will attain ARARs (unless
use of other waivers is justified). Closure requirements witl be
addressed for all of OU 3 in the final ROD.
21
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2.8.3
Criterion 3: Long-term Effectiveness and Permanence
This criterion reflects an emphasis on implementing remedies that will
ensure protection of human health and the environment in the long-term
as well as in the near term. The assessment of alternatives against this -
criterion evaluates the residual risks at the site after completion of the
. interim remedial actions.
Neither alternative is considered permanent because ~ource material is
left in place, which could result in future human exposures to
contal'!'inated soil or ground water. Under the first alternative, removal
of the tanks will not prevent the percolation of surface water through
the excavated area; hence NaOH may continue to migrate down to the
shallow ground water. However, as long as the cap is intact, the
selected alternative provides long-term effectiveness by reducing the
percolation of surface water through the contaminated soil. This
-reduction in percolation slows the rate ot migration of the NaOH which
in turn -reduces the rate of contaminant release to ground water. To .
maintain long-term effectiveness, - the operations plan - for this
. alternative should include regular maintenance of the cap until the final.
remedies for OU 3 are enacted. Therefore, the selected alternative is
more favorable than the first alternative under this criterion.
2.8.4
- .
Criterion 4: Reduction of Toxicity, Mobility, or
Volume through Treatment
This criterion addresses the statutory preference for - remedies that
employ treatment as a principal element. The assessment against - this
criterion evaluates the anticipated performance of the specific
treatment technologies an alternative may employ.
Neither alternative employs treatment (or resource - recovery
technologies) as a principal element. Containment by capping - is an
interim action and treatment is not within the limited scope - of the
action. As described previously, the intended scope of the containment
alternative is to reduce the mobility of NaOH.
2.8.5
Criterion 5: Short-term Effectiveness
This criterion addresses- short-term impacts of the alternatives. The
assessment against this criterion examines the effectiveness of
alternatives in protecting human health and the environment during the
construction and implentation of a remedy until the response objectives
have been met.
7.2
-------
When implementing either alternative, there may be some short-term
risks for workers at or near the NaOH tank excavation site as a result of
the caustic nature' of the contaminant. These potential risks would'
result from inhalation of dust due to disturbance of the contaminated
soil and direct dermal contact. These risks can be easily controlled with". .
reasonable caution in excavation procedures, designation. of' exclusion:" .
and limited access zones, wearing appropriate respiratory protection
equipment, or implementing engineering controls;" such'. as . dust
suppression. There should be no significant adverse environmental
. impacts as a result of this action. The removal can be complettd, and
the site can be regraded in a matter of a f~w weeks. Both alteittatives
rate evenly under this criterion. '
2.8.6
Criterion 6: Implementability
. The assessment against thiS criterion evaluates the' technical and
administrative fe.asibility of the alternativ.es and the availability of the
goods and services needed to implement th.em.
. .
No implementation problems are anticipated for either alternative. The.
equipment required for construction is readily available and reliable.
Hill AFB has funding mechanisms and contractors aVf;lilable to provide
financial and logistical support. Administrative coordination for. Hill
AFB, EPA, and UDERR will include permitting requirements (digging
permit, tank removal, etc.); site access; and administrative requirements
for only the storage of any hazardous wastes, because there will be no
transportation of hazardous waste. The. first alternative is more
implementable, although the selected alternative will still be easy to
implement.
. 2.8.7
Criterion 7: Cost
This criterion encompasses all engineering, construction, and operation
and maintenance costs incurred over the life of the project. The
assessment against this criterion is based on the present worth of these
costs for each alternative. Present worth is a method of evaluating
expenditures that occur over different lengths of time. This allows the
costs for different remedial alternatives to be compared on the basis of
a single figure for each alternative by discounting all costs to the year
that the alternative is implemented. The present worth of a project
represents the amount of money which, if invested in the initial year of
the remedy and disbursed as needed, would be sufficient to cover all the
costs associated with the remedial action. Legal, permitting, and costs
associated with administering the alternatives have not been included in
the analyses but will not result in cost figures exceeding EP A
23
-------
recommended accuracy guidelines of" -30 percent to +50 percent (U.S.
EPA, 1 988)..
There are no costs associated with the first alternative over and' above
those associated with removal of tanks and backfilling. The direct
capital cost of the selected alternative is estimated to be $54,000, in
- addition to UST removal. No indirect operational expenses are expected
to be incurred, and annual maintenance is estimated" ;at 1 percent, or
$540 per year, until the final remedies for au 3 a~e enacted. The total
three-year present worth cost for the selected alternative is $55,343
and it will take from one to four months to impl~ment the action.
2.8.8
Criterion 8: State/Support Agency Acceptance
This criterion, which is an" ongoing concern throughout the remedial
process, reflects the agreement with, opposition to, or comments on the
selected alternative by state/support age.ncies. " In this case, EPA and
UDERR concur with the selected interim remedial action.
" 2.8.9" Criterion 9: Community Acceptance
This criterion reflects the community's apparent preferences among or
concerns about alternatives. As a result of the public comment process,
no comments were received that either agreed with or opposed either of
the interim remedial alternatives. Additional detail on the public
comment process is given in section 3.0. "
2.9
Selected Remedy
The selected interim action (temporary cap) provides the best balance of
trade-offs among the nine criteria for evaluation compared to the first
alternative (no action). The first alternative is more easily implemented
and" less costly than the selected alternative. Both alternatives rate
" evenly "for short-term effectiveness. The State of Utah accepts the
preferred alternative. No oral or written comments were received to
evaluate community acceptance. Both alternatives are presumed to rate
equally under community acceptance. In all of the other criteria, the
selected alternative provides greater overall protection of human health
and the environment, is- in furtherance of compliance with ARARs,
provides greater long-term effectiveness, and will reduce contaminant
"mobility in the subsurface.
The asphalt cap of the selected interim action is a containment
technology, and capping is the process option. No performance standards
are being addressed at this time. Performance standards for
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contaminants of concern and specific points of compliance will be
addressed in the ROD for all of OU 3. The basis for setting remediation
. goals is the' reduction of mobility of the sodium hydroxide in the
unsaturated zone and minimizing degradation of shallow ground water
quality. State of Utah requirements are not more stringent than Federal
standards. No residuals will be generated during the interim remedial
o'action. .
The selected action is interim. The cap will be modified, removed, or
retained as necessary to be consistent with final remedial actions. With
the exception of the minor inconvenience of drilling through the asphalt,
this activity will not limit additional efforts to investigate and
characterize this site. . .
Performance standards for contaminants of. concern for this interim
action have not been addressed in this document. Performance standards
for the Sodium. Hydroxide Tank Site will b~. addressed in the final ROD for
all of OU 3. Similarly, specific points of compliance for the soils
addressed by this interim action. have ~ot been defined, but will instead
be designated in the final ROD for all of OU 3 and in the final response
o action. In general, the area of attainment is the volume of soil from
which NaOH would continue to leach if the cap were. not constructed.
2.10
. Statutory Determinations
The selected remedy meets the statutory requirements of CERCLA as
amended by SARA. Thes~ requirements include protection of human
health and the environment, compliance with ARARs, cost effectiveness,
utilization of permanent solutions. and alternative treatment
technologies to the maximum extent practicable, and preference for
treatment as a principal element. The manner in which the selected
remedy for this interim action meets each of these requirements is
presented in the following discussion. The statutory determinations for
the selected remedy for soils, ground water, surface water, and air will
be discussed in the ROD for all of OU 3, which will be prepared following
the initiation of this interim action and the collection and analysis of
additional monitoring data.
2.10.1 Protection of Human Health and the' Environment
This interim action protects human health and the environment through
management of a hazardous substance (NaOH) to avoid the threat of a
release. The interim action will prevent exposure of receptors to
contaminated, near-surface soils. Temporary capping will reduce the pH
and concentration of NaOH in the mixture of ground water and leachate.
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2.10.2 Complianc;e With ARARs
The no-action alternative postpones meeting ARARs until the final
remedy(ies) are implemented. Containment by capping represents a
preliminary step in achieving action-specific ARARs for" the". soils.
. Federal and State requirements related to the removal and disposal of
the tank system will be complied with by meeting ~onditions of the
permit "for removal of the underground storage tanks used to store NaOH.
No contaminant-specific ARARs exist for NaOH in soils. Potential ground
water chemical-specific ARARs will be addressed in evaluating final
remedial alternatives for OU 3. No location-specific ARARs have been
identified. The site is not located within a 100-year flood plain,
wetland, historical site, or sensitive ecosystem or habitat.
Action-specific ARARs that" will be met pertain to dusty conditions
during cap construction and temporary con.~rol of the source.
The selected remedy invokes a waiver of RCRA closure requirements on.
the basis that this remedy is part of an interim remedial action..
" Compliance with the closure requirements will occur through the final
remedial action for OU 3 (unless use of other waivers is justified).
2.10.3 Cost Effectiveness
" The no action alternative initially appears to be the most cost effective
alternative. However, that alternative may require a greater expenditure
after the ROD for all of OU 3. If the interim action is not undertaken,
contamination will continue to migrate into soil and/or ground water,
probably increasing ultimate remediation costs for OU 3. Therefore, the
selected remedy is cost effective in terms of reduction in threat to
public health and the environment per dollars expended when remediation
for all of OU 3 is" considered.
2.10.4 Utilization
Treatment
Practicable
of Permanent
Tech no log ies
Solutions or Alternative
to the Maximum Extent
As this is an interim action, the selected remedy is not designed or
expected to be final. However, the selected remedy represents the best
balance of tradeoffs with respect to pertinent criteria given the limited
scope of the action. The interim action will reduce mobility of
contaminants due to construction of the temporary cap, for as long as
the cap remains in place.
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2.10.5 Preference. for Treatment as a Principal Element
As explained in section 2.8.4, the temporary cap will be in furt~erance of
the statutory preference for reducing toxicity, mobility, or volume
through treatment. The mobility of NaOH will be substantially reduced
under the selected alternative (temporary asphalt cap) as compared to
. the first alternative. No treatment will be utilized as part of this
interim action. The preference for treatment will be ~ddressed in the
ROD for all of OU 3.
2.11
Documentation of Significant Chan.ges
The selected interim action is the same as the preferred alternative
presented in the proposed plan for interim action at the Sodium
Hydroxide Tank Site. There have been no changes relative to the proposed
plan. ",
3.0
Responsiveness Summary
Section 2.3 explains in greater detail the community involvement
process for this interim action. In summary, a public comment period
was held from 30 January 1992 through 2 March 1992. A public meeting
was held on 13 February 1992 to present the results of and to solicit
public comments on the focused RI/FS and the alternatives as presented
in the Proposed Plan for the operable unit.
No comments were received by Hill AFB pertaining to the interim action
at the Sodium Hydroxide Tank Site, either at the public meeting or in
writing. Therefore, there is no response to. comments.
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List of References
Code of Federal Regulations (CFR), U.S. Government Printing Office,
. various sections and parts.
.James M. Montgomery, Consulting Engineers, Inc. (JMM). Draft Final
Baseline Risk Assessment for Operable Unit 3 at Hill Air Force
Base, Utah, December, 1 991.
James M. Montgomery, Consulting Engineers, Inc. (JMM). Draft Final
Focused RifFS for the Sodium Hydroxide Tank Site at Operable Unit
3 at Hill Air Force Base, Utah, January, 1992. .
James M. Montgomery, Consulting Engineers, Inc. (JMM). Draft Final
Remedial Investigation Report for Operable Unit 3 at Hill Air Force
Base, Utah,. April, 1992.
..
James M. Montgomery, Consulting Engineers, Inc. (JMM). Final Addendum
to the Remedial Investigation Work Plans for Operable Unit 3 at
Hill AFB, Utah, December, 1989.
James M. Montgomery, Consulting Engineers, Inc. (JMM). Installation
Restoration Program Final Remedial Investigation Work Plans for
the Remedial Investigation Feasibility Study (RifFS) of the Sodium
Hydroxide Tank Site and the IWTP Sludge Drying Beds, Hill AFB,
Utah, June, 1988. .
James M. Montgomery, Consulting Engineers, Inc. (JMM). Installation
Restoration Program Site Inspection Report for the Remedial
Investigation and Feasibility Study (RifFS) of the Sodium Hyd . xide
Tank Site and the IWTP Sludge Drying Beds, Hill AFB, utah,
February, 1988.
Radian Corporation (Radian). Phase II Stage 2 Investigation Completed
Under the Installation Restoration Program (IRP).
U.S. Air Force (USAF). Installation Restoration Program Environmental
Community Relations Plan, Hill AFB, Utah, February, 1992.
u.S. Air Force (USAf). Proposed Plan for a CERCLA/IRP Interim Action at
the Sodium Hydroxide Tank Site, January, 1992.
U.S. Environmental Protection Agency (U.S. EPA). Guidance for Conducting
Remedial Investigations and Feasibility Studies Under CERCLA,
Interim Final, 1988.
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U.S. Environmental Protection Agency (U.S. EPA). Superfund LDR Guide #5
- Determining When Land Disposal Restrictions (LPRs) Are.
Applicable to. CERCLA Response Actions, D.irective 9347.3-0SFS,
Office of Solid Waste and Emergency Response, July, 1989.
-U.S. Environmental Protection Agency (U.S. EPA) Region VIII, Utah
Department of Health (UDOH) and United States ,Air Force (USAF),.
Federal Facility Agreement (FFA) Under CERCLA Section 120, April,
,.991 (The State of Utah now administers the FFA through the Utah
Division of Environmental Response and - Remediation (UDERR), a
divison of the Utah Department of Environmental Quality (UDEQ».
Utah Administrative Code (UAC). Utah Division of Administrative Rules,
Department of Administrative Services, January, 1990.
..
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