United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R10-93/064
May 1993
SEPA Superfund
Record of Decision:
Mountain Home Air Force
-------
50272.101
REPORT DOCUMENTATION 11. REPORT NO. l.
PAGE EPA/ROD/R10-93/064
2.
3. Reclplant'. Acc88.lon No.
4.
Tltla and Subtitle
SUPERFUND RECORD OF DECISION
Mountain Home Air Force Base, ID
Second Remedial Action
Author(.)
5.
Raport Deta
OS/24/93
6.
7.
8.
Parformlng Organization Rept. No.
9.
Performing Organlzetlon Neme and Addr-
10
Project Ta.klWork Unit No.
(J
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponeoring Org.nlzetlon Heme and Add,...
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Raport & Period Coverad
Agency
800/800
14.
15. Supplamantary Note.
PB94-964616
16. Abatract (Limit: 200 word.)
The 130-acre B-Street Landfill is part of the Mountain Home Air Force Base located
approximately 10 miles southwest of Mountain Home, Elmore County, Idaho. Land use in
the area is predominantly residential and agricultural with approximately 7,000 people
residing on the Base. Ground water is the source of drinking water and is also a
source of irrigation and drinking water for nearby farm residents. The B-Street
Landfill is located in the northwest corner of the base in an industrial area that is
situated close to the runway and other industrial/occupational facilities. Between 1956
and 1969, the landfill served as the main disposal area for municipal solid waste at
the base. It also served as a disposal site for miscellaneous construction debris,
rubble, empty drums, and coal ash until 1990, when the majority of landfilling activity
ceased. Occasionally asbestos-containing material was disposed in one of the trenches.
The landfill consists of five areas: a trench area, consisting of five trenches that
received general refuse, empty cans and drums, including empty pesticide drums, and
industrial wastes such as petroleum, oil and lubricant (POL) wastes, oils, solvents,
jet fuels, and tank cleaning sludge; a drum disposal area that was used for surface
storage of drums containing solvents, waste fuels, other petroleum products, and
pesticides; an ash disposal area where approximately 924,000 ft3 of ash from the
(See Attached page)
17. Document Analyale a. Dncrlptors
Record of Decision - Mountain
Second Remedial Action
Contaminated Medium: None
Key Contaminants: None
Home Air Force Base, ID
b.
IdantiliarslOpan-Endad Tarma
c.
COSATI Field/Group
18. Av.llablilty Statament
19. Security Class (ThIs Report)
None
20. Security Class (ThIs Page)
None
21. No. of Pages
96
22: Price
(SM ANSI.Z39.18)
SHlnstructlons on RBVBrss
OPTIONAL FORM 272 (4.77)
(Formerty NTI5-35)
-------
EPA/ROD/R10-93/064
Mountain Home Air Force Base, ID
Second Remedial Action
Abstract (Continued)
coal-firing power plant were disposed; a rubble area that comprises more than half of the
landfill and contains surface deposits of debris, such as concrete, asphalt, and ash; and
a burn area that was used to burn trash including roots, wood, and other combustible
items. Additionally, up to 20 drums of DDT may have also been placed in the trenches,
however, this has not been verified by historical records. In 1982, the U.S. Air Force
(USAF) began conducting environmental assessments at the base and identified areas with
the greatest potential for environmental impact, one of which was the B-Street Landfill.
A 1992 ROD addressed onsite soil at the Fire Training Area, as OU4. Future RODs will
address ground water contamination and other Source areas. This ROD provides a final
remedy for the onsite soil, as OU2. Subsequent investigations have determined that
chemical concentrations in the soil at the landfill pose no unacceptable risk to human
health or the environment and that no further remedial action is necessary; therefore,
there are no contaminants of concern at the site.
The selected remedial action for this site is no further action. Based On the results of
the human health risk assessment, the USAF, EPA, and the State have determined that the
chemicals concentrations in the soil pose no unacceptable risks to human health or the
environment. There are no costs associated with this no action remedy.
PERFORMANCE STANDARDS OR GOALS:
-------
MOUNTAIN HOME AIR FORCE BASE, MOUNTAIN HOME, IDAHO
DECLARATION FOR THE RECORD OF DECISION
LANDFILL NO.2, OPERABLE UNIT 2
SITE NAME AND LOCATION
~
Mountain Home Air Force Base, LF-02
Landfill No.2 (B Street Landfill), Operable Unit 2
Mountain Home, Elmore County, Idaho
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected final remedial
action for Landfill No.2 (B Street Landfill, LF-02) at Mountain
Home Air Force Base in Mountain Home, Idaho. The selected remedy
was chosen in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA or
Superfund), 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 lead agency for this decision is the U.S. Air Force (USAF).
The U.S. Environmental Protection Agency (EPA) approves of this
decision and, along with the state of Idaho Department of Health
and Welfare (IDHW), has participated in the scoping of the site
investigation and evaluation of remedial investigation report.
The State of Idaho concurs with the selected remedy.
DESCRIPTION OF THE SELECTED REMEDY
USAF, EPA, and IDHW have determined that no remedial action is
necessary under CERCLA at the B Street Landfill to ensure
protection of human health and the environment. This decision is
based on the results of the Remedial Investigation (RI) and
baseline human health risk assessment and ecological evaluation.
The risk assessment determined that hazardous substances
remaining in the soil pose no unacceptable risks to human health
or the environment under current and probable future use
scenarios. Because there are uncertainties associated with the
assumptions used in the groundwater model, the Operable Unit 3
(OU 3) base-wide groundwater investigation and verification will
address whether monitoring is needed at B Street Landfill.
DECLARATION STATEMENT
The no action remedy is protective of human health and the
environment. However, there are uncertainties associated with
-------
the number of samples collected and the heterogeneous nature of
the wastes. Additionally, there is the possibility of trench
disposal in the Rubble Area. For these reasons, the no action
remedy may result in hazardous substances remaining on-site that
do not allow for unlimited use and unrestricted exposure.
Therefore, a statutory 5 year review will apply to this site.
-0
II
-------
Signature sheet for the foregoing Landfill No.2
Decision between the u.S. Air Force and the u.S.
Protection Agency, with concurrence by the Idaho
Health and Welfare.
Record of
Environmental
Department of
,F?
~~
~/2}i(q5
Date
Dana A. Rasmussen
Regional Administrator, Region 10
U.S. Environmental Protection Agency
ill
-------
signature sheet for the foregoing Landfill No.2
Decision between the U.S. Air Force and the U.S.
Protection Agency, with concurrence by the Idaho
Health and Welfare.
~~~
WILLIAM S. HINTON, JR .
Brigadier General, USAF
Commander, 366th Wing
~
\~ \. ~
~ ~ ~ ~ \O:JO:J~ t<\rv\
-a... ~. ~\;,'\. ~~~ ~
~ ~ ~~
~~
~....~
iv
Record of
Environmental
Department of
2&~'3
-------
Signature sheet for the foregoing Landfill No.2
Decision between the U.S. Air Force and the U.S.
Protection Agency, with concurrence by the Idaho
Health and Welfare.
(/'
~/~
Jerry L. H~
Director
Idaho Department of Health and Welfare
v
..
- ~;' ...
Record of
Environmental
Department of
~~s/Y 3"
/' Date
~ EA~G~! 1~3E aJJ .
; IDAHO O~E~ATlONS Or'F/Cr
,
-------
MOUNTAIN HOME AIR FORCE BASE
B STREET LANDFILL
MOUNTAIN HOME, ELMORE COUNTY, IDAHO
INTRODUCTION
Mountain Home Air Force Base (the Base), near Mountain Home,
Idaho, was listed on the National Priorities List (NPL) in August
1990, under the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA, or Superfund),
as amended by the Superfund Amendments and Reauthorization Act of
1986 (SARA).
In 1992, the United States Air Force (USAF) performed a Remedial
Investigation (RI) and baseline human health risk assessment for
Landfill 2 (LF-02), also known as the B Street Landfill, which is
included in Operable Unit 2 (OU2). The RI was performed in
accordance with Executive Order 12580 (Superfund Implementation)
and the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). The RI characterized the nature and
extent of contamination in soils for the B Street Landfill and
evaluated potential effects on groundwater, using a computer
model. The USAF also conducted a baseline human health risk
assessment for the B Street Landfill to evaluate potential
effects of the landfill contaminants on human health. Potential
environmental risks were also evaluated in the risk assessment.
This document is a Record of Decision (ROD) that presents the
selected no action remedy for the B Street Landfill and provides
the rationale for that selection, in accordance with the NCP.
I.
SITE NAME, LOCATION, AND DESCRIPTION
Mountain Home AFB is located in a rural agricultural area about
10 miles southwest of Mountain Home in Elmore County, Idaho
(Figure 1). The Base occupies an area of 9 square miles. The
total resident population of Mountain Home AFB is about 7,000
people.
22835A/89MCl14H/R17 08-09-93(3:24pm)/RPT III
-------
The Snake River is about 2.5 miles south of the Base, but no
permanent streams exist on or near the Base. Groundwater is
found at approximately 350 feet below ground surface (bgs).
,?
Groundwater is the source of drinking water at the Base and is a
source of irrigation and drinking water for nearby farm
residents. The Base has nine Base Production Wells (BPWs); the
closest production well to the B Street Landfill is BPW No.2,
which is located approximately two-thirds mile southeast of the B
Street Landfill (Figure 4).
B Street Landfill is located in the northwest corner of the Base
in an industrial area within close proximity to the runway and
other industrial and occupational facilities. The nearest
residence to the B Street Landfill is on the Base, approximately
one mile to the southeast of the landfill. Off the Base, land
use adjacent to the B Street Landfill is agricultural.
The B street Landfill encompasses approximately 130 acres and
consists of a Trench Area, Drum Disposal Area, Ash Disposal Area,
Rubble Area, and Burn Area (Figure 2). All areas of the B Street
Landfill have been closed since 1990, with the exception of
Trench 3. Trench 3 continues to receive asbestos waste on a
periodic basis and is regulated by the Toxic Substance Control
Act (TSCA).
The Trench Area contains five trenches. Four of the trenches are
located in the southwest part of B Street Landfill. The fifth
trench is located approximately 1,000 feet to the north. Trench
3, the asbestos waste trench, was not included as part of the OU2
investigation because it is regulated under TSCA rules. The Drum
Disposal Area, once used to store drums, is a small site (80 feet
to 100 feet diameter) located in the north part of B Street
Landfill. Although the volume of material in the drums stored at
the Drum Disposal Area is not known, sample results indicate low
levels of contamination in the soil. The Ash Disposal Area is
approximately 1,000 feet by 1,000 feet, where discrete piles of
coal ash from the coal-firing power plant were disposed. The
Rubble Area comprises more than 50 percent of the landfill and
primarily consists of runway debris and other concrete rubble
2283SA/89MCl14H/RI7 08-09-93(3:24pm)/RPT III
-------
placed on the land surface. An interview with a former employee
indicated that additional trenches may be present underneath a
portion of the Rubble Area, although this has not been verified
in available records. In addition, a subsequent interview with
the same former employee did not corroborate the existence of the
trenches. The Burn Area consists of a site about 20 feet by 20
feet where trash such as wood, roots, and other miscellaneous
items were burned.-
II.
SITE HISTORY. RESPONSE HISTORY. AND ENFORCEMENT ACTIVITIES
A.
SITE HISTORY
The B-Street Landfill served as the main Base sanitary landfill
between 1956 and 1969. It also served as a disposal site for
construction debris, rubble, empty drums and coal ash until 1990,
when all landfilling activity ceased except for occasional
disposal of asbestos waste in Trench 3, which is regulated by
TSCA. B street Landfill consists of a Trench Area, Drum Disposal
Area, Ash Disposal Area, Rubble Area, and Burn Area. Each area
is described below.
1.
Trench Area
The Trench Area served as the main Base sanitary landfill between
1956 and 1969. A total of five trenches were excavated.
Excavation of the first trench began in 1955. By 1969, five
trenches had been excavated and one trench was filled.
Photographs taken in 1977 and 1988 show little or no change from
photographs taken in 1969. Locations of the trenches are shown
on Figure 2.
Trenches 1, 2, and 4 are about 50 feet in width by 400 feet in
length; Trench 5 is about 40 feet by 100 feet. The depths of the
trenches, as shown by the field investigation, ranged from 6 to
17 feet for Trench 1, from 6 to 9 feet for Trench 2, and from
zero to 4 feet for Trench 4. Trench 5 is a surface scrape with
bedrock at a depth of less than 1 foot. The trenches are covered
by native soil with thicknesses ranging between 1 to 5 feet. As
22835A/89MCl14H/R17 08-09-93(3:24pm)/RPT 111
-------
stated earlier, Trench 3 is not included in this investigation of
the B street Landfill.
/'
The following materials are believed to have been disposed of in
the trenches (excluding Trench No.3, the asbestos trench):
general refuse; garbage; empty cans and drums, including empty
pesticide drums; and industrial wastes such as petroleum, oil,
and lubricant (POL) wastes, oils, solvents, jet fuels, and tank
cleaning sludge (oil/water separator sludge). Up to 20 drums of
DDT may have been placed in the trenches. However, this has not
been verified by historical records, interviews, or field
investigations.
Wastes were reportedly routinely burned and covered with native
soils on a weekly basis after disposal in the trenches. General
refuse and industrial wastes appear to have been randomly
disposed together in the trenches.
2.
Drum Disposal Area
The Drum Disposal Area was once used to store drums on the soil
surface. No burial of drums occurred. Drums once stored at the
site may have contained solvents, waste fuels, other petroleum
products, pesticides, or herbicides. Although the volume of
material in the drums stored at the Drum Disposal Area is not
known, sample results indicate low levels of contamination in the
soil. The soil layer above the bedrock is shallow (0.5 to 1 foot
thick), although thicker piles of soil, ash, and other debris are
present.
The Drum Disposal Area is roughly round and about 80 to 100 feet
in diameter, with an oval-shaped depression about 20 feet across
and 2 to 3 feet deep within the round area. various debris,
scrap metal, and several 5-gallon buckets of pavement crack
sealer were observed during the field investigation. Fifty-five
gallon drums were not observed during the field investigation.
22835A/89MClI4H/RI7 08-09-93(3:24pm)/RPT /11
-------
3.
Ash Disposal Area
Ash from the coal-firing power plant was placed in the Ash
Disposal Area. The total volume of ash disposed of in this area
is estimated to be approximately 924,000 cubic feet. There is no
evidence of other potentially hazardous materials being placed in
this area. The Ash Disposal Area is approximately 1,000 feet by
1,000 feet and lies between the Trench and Drum Disposal Areas
(Figure 7).
4.
Rubble Area
The Rubble Area comprises more than half of B street Landfill.
This area contains surface deposits of debris, such as concrete
from runway renovation, asphalt, and ash from the coal-fired
power plant. No known or suspected hazardous material disposal
activities occurred on the ground surface at the Rubble Area. A
former Mountain Home AFB employee has indicated that refuse
trenches may underlie the Rubble Area. However, this has not
been verified by aerial photographs, other historical records, or
other interviews with employees.
Aerial photographs and interviews indicate that borrow pits
dug in the north and northeast areas of the landfill and on
south side of B street road near monitoring well 5 and that
areas were not used for landfilling wastes (see Figure 4).
were
the
these
5.
Burn Area
The Burn Area consists of a site about 20 feet by 20 feet. The
area was used to burn trash, such as roots, wood, and other
miscellaneous combustible items. No known or suspected hazardous
material disposal activities occurred. Therefore, no sampling
was conducted for the RI. In 1991, the area was observed to
contain some miscellaneous debris, such as wood.
B.
RESPONSE HISTORY
In 1982, the USAF began conducting environmental assessments at
Mountain Home AFB under the Department of Defense (DOD)
2283SA/89MCl14H/R17 08-09-93(3:24pm)/RPT /11
-------
Installation Restoration Program (IRP). The purpose of the
program is to evaluate past and current use of toxic and
hazardous materials and to assess the potential for off-site
migration of such materials.
A Phase I Records Search was conducted that identified three
sites at the Base with the greatest potential for environmental
impact, one of which was the B Street Landfill. A monitoring
well was installed at the B Street Landfill as part of the Phase.
II Stage 1 site Investigation. During a Phase II Remedial
Investigation conducted in 1987 and 1988, three additional
groundwater monitoring wells were installed at the Trench Area.
Soil samples were collected at the Trench Area and Drum Disposal
Area. The sampling and analytical program detected little
evidence of contamination in soil, except for elevated
concentrations of a few semivolatile organic compounds
(phthalates) and petroleum hydrocarbons in several soil samples.
No evidence of groundwater contamination was detected in the
monitoring wells. However, it has not been confirmed that
existing wells are downgradient, and therefore, representative of
possible groundwater contamination from the site.
In August 1990, Mountain Home AFB was listed on the
CERCLA because of detection of halogenated methanes
organic compounds in Base drinking water wells.
NPL under
and other
Following listing on the NPL, additional remedial investigation
was undertaken at the B Street Landfill. This investigation was
necessary to characterize the nature and extent of contamination
at the B Street Landfill and to assess the potential for adverse
effects on human health and the environment.
C.
ENFORCEMENT ACTIVITIES
On January 29, 1991, USAF, EPA, and IDHW entered into a Federal
Facilities Agreement (FFA). The FFA established a procedural
framework and schedule for developing, implementing, and
monitoring appropriate response actions conducted at Mountain
Home. Under the terms of the FFA, EPA and IDHW provided
22835A/89MCI14H/R17 08-09-93(3:24pm)/RPT /11
-------
oversight of subsequent RI activities and agreed on the final
remedy set forth in this ROD.
I:IJ:.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
Public participation requirements under Sections 113(k) (2) (B) (i-v)
and 117(a) of CERCLA, 42 U.S.C. SS 9613(k) (2) (B) (i-v) and 9617,
were satisfied during the RI process. The Mountain Home AFB
Public Affairs Office has primary responsibility for conducting
the community relations program. The following community
relations activities were conducted during this RI:
.
Creation of a Community Relations Plan as part of the
overall management plan for OU2. The Community
Relations Plan was designed to promote public awareness
of the investigations and public involvement in the
decision-making process.
.
Establishment of an Administrative Record to provide"
the basis for the selected remedy. The Administrative
Record is available for public review in the
information repository at the following locations:
Mountain Home Public Library
790 North 10 East
Mountain Home, Idaho 83647
Phone: (208) 587-4716
Mountain Home Air Force Base
1100 Liberator
Mountain Home, Idaho 83648-5426
Phone: (208) 828-2750
.
Creation and distribution of a Proposed Plan for the no
action alternative at the B Street Landfill. The
purpose of the Proposed Plan was to provide the public
and other interested parties with the information that
was used to come to the no action determination and to
announce the public comment period and public meeting
dates.
..
22835A/89MCl14H/R17 08-09-93(3:24pm)/RPT /11
-7-
-------
!>
.
Distribution of periodic news releases and fact sheets
announcing various on-site activities, results of
investigations, and explanations of the investigative
process. These included:
1.
A news release on January 22, 1993, to the list of
contacts and interested parties noted in the
Community Relations Plan and to various local
newspapers, radio stations, and television
stations advertising the public meeting for B
street Landfill at the Mountain Home High School
on February 11, 1993.
2.
A paid advertisement in the Mountain Home and
Idaho Statesman newspapers was run on January 27,
1993, and February 9 to February 11, 1993,
respectively, announcing the public meeting at the
Mountain Home High School.
.
Development of a mailing list composed of persons
interested in the project and public officials.
.
Commencement of a public comment period on the no
action alternative from January 27, 1993, to
February 25, 1993.
.
Discussion of the no action alternative and receipt of
public comments at the public meeting held on
February 11, 1993, at the Mountain Home High School,
Mountain Home, Idaho.
.
Consideration of oral and written comments in selection
of the no action alternative. The comments and
responses are summarized in the Responsiveness Summary
section of this ROD.
.
Preparation of a responsiveness summary that addressed
comments and questions received during the public
comment period on the RI and Proposed Plan and
inclusion in this ROD.
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT /11
-------
Public interest in the B street Landfill site has been low
throughout the history of site investigative activities. No
public concerns or issues were raised during the investigation.
-r
I
IV.
SCOPE AND ROLE OF OPERABLE UNIT AND RESPONSE ACTION
There are several sites at the Base which may contain hazardous
substances that pC.e a threat to human health and the
environment. A sit~ is a specific location where a hazardous
substance may have been stored or disposed. These sites are
divided into manageable operable units (OUs) consisting of one
site or a group of sites, which can logically be investigated as
part of one unit. Currently, the Base is divided into six OUs.
These OUs and their status are:
.
OU 1 - A Limited Field Investigation (LFI) was performed on
21 sites and has been completed.
.
OU 2 - A RI and baseline human health
ecological evaluation on the B Street
Lagoon Landfill sites were performed.
includes the risk assessment at the B
is the subject of this ROD.
risk assessment and
Landfill and the
The RI, which
street Landfill site,
.
OU 3 - A Base-wide Groundwater Remedial
Investigation/Feasibility Study and baseline human healt~
risk assessment (RI/FS), a base-wide ecological risk
assessment and a RI/FS at source areas SS-ll, RW-14, ST-13,
ST-31, ST-32, ST-34 and ST-35 are currently being performed.
This OU is planned to be the final OU at the Base.
.
OU 4 - An RI with a baseline human health risk assessment at
Fire Training Area 8 was completed. It was determined that
the site does not pose an unacceptable risk to human health
and the environment, and a no action ROD was signed in June
1992.
.
OU 5 - A removal action at the Low-Level Radioactive
Material Burial Site was completed.
22835A/89MCl14H/R17 OS-09-93(3:24pm)/RPT /11
-------
.
au 6 - A RI/FS is currently being performed at the
Entomology Shop, Former Auto Hobby Shop, Flight Line Storm
Drain, and Vehicle Wash Rack sites. A LFI is also being
performed at the Munitions Disposal/Popping Furnace, Drum
Accumulation Pad, and Fire Training Area 8 Underground
Storage Tank sites. au 6 is scheduled to be completed prior
to au 3.
".
"
.'"
au 2 Response Action Determination
The results of the RI at the Lagoon Landfill indicate that
additional data on groundwater is needed to make a decision on
remedial action. Additional data needs and the remedial action
decision at the Lagoon Landfill site will be addressed as part of
au 3.
For the B Street Landfill, the RI and baseline human health risk
assessment evaluated the nature and extent of soil contamination
through soil sampling and analysis. A computer model was used to
evaluate the potential for leaching of contaminants to
groundwater. The baseline human health risk assessment
quantitatively assessed potential health risks from exposure to
chemicals of concern at the landfill by soil, air, and
groundwater exposure pathways and qualitatively assessed the
potential for significant adverse environmental impacts. A
base-wide ecological assessment is being conducted in a separate
operable unit (aU 3). In addition, because there are
uncertainties associated with the assumptions used in the
groundwater model, the au 3 base-wide groundwater investigation
and verification will address whether monitoring is necessary at
B Street Landfill.
Based on the results of the RI and baseline human health risk
assessment and ecological evaluation, no remedial action under
CERCLA is necessary to ensure protection of human health or the
environment under current and probable future use scenarios.
However, because there are uncertainties associated with the risk
assessment at the Trench Area (due to the number of samples
collected, the heterogenous nature of the wastes, and the
possibility of trench disposal in the Rubble Area), the no action
..
2283SA/89MCl14H/R17 08-09-93(3:24pm)/RPT III
-------
remedy may result in hazardous substances remaining on-site that
do not allow for unlimited use and unrestricted exposure.
Therefore, a statutory 5-year review of the site will apply.
'.
v.
SUMMARY OF SITE CHARACTERISTICS
A.
TOPOGRAPHY, SURFACE FEATURES, AND CLIMATE
Mountain Home AFB.is located on the Mountain Home Plateau, a
rolling upland plain covered primarily with lava and windblown
sediment. Scattered shield volcanoes and cinder cones rise
several hundred feet above the plain. The plateau slopes gently
downward toward the north, west, and southwest. Elevations range
from 2,700 to 3,200 feet above mean sea level (MSL). The
topography at the B Street Landfill is essentially flat, with an
average elevation of 3,020 feet MSL over most of the site,
including some depressions and small topographic highs.
The Snake River forms the southern and southwestern boundary of
the Mountain Home Plateau. The plateau is drained by a series of
intermittent streams that discharge to the Snake River during
rainy periods.
The climate at Mountain Home AFB is arid. The area receives
about 8 inches of precipitation annually. Evapotranspiration
(ET) has been calculated by Mundorff at 5 to 9 inches per year.
This results in an annual net precipitation of about +3 inches to
-1 inch. The 100-year, 24-hour storm event results in 2 inches
of precipitation. The 2S-year, 24-hour storm event results in
1.6 inches of precipitation.
Area wind directions are highly variable, arising predominantly
from the northwest during the spring and summer and from the east
and east-southeast during the fall and winter.
22835A/89MC1l4H/R17 08-09-93(3:24pm)/RPT /11
-------
B.
REGIONAL AND SITE GEOLOGY
1.
Regional Geology
."
The Mountain Home Plateau, on which Mountain Home AFB is located,
is underlain by over 10,000 feet of volcanic and sedimentary
rocks. The principal geologic formations of interest are the
Glenns Ferry Formation, the Bruneau Formation of the Idaho Group,
and the Snake River Group, which is the uppermost bedrock unit.
The Snake River Group, which is 550 feet thick, consists of
several basalt flows and unconsolidated alluvial deposits. The
basalt originated from volcanic sources as much as 60 miles east
of Mountain Home AFB. The Snake River Group forms the bedrock at
Mountain Home AFB and elsewhere in the Mountain Home Plateau.
Wind-blown and alluvial deposits overlie the Snake River Group.
These deposits consist of a layer of unconsolidated silt and sand
ranging in thickness from several inches to approximately 30
feet.
2.
Site Geology
Four monitoring wells (MW-2, MW-3, MW-4, and MW-5) were drilled
at the B Street Landfill in 1984 and 1987 (Figure 2). Basalt was
encountered in all four monitoring well borings at 18, 7, and 4
feet below ground surface (bgs) , respectively, and continued to
the boring completion depths. Some shale zones were noted at
various depths within the basalt. Overlying the basalt is a
deposit of wind-blown silt and sand containing some caliche
(calcium carbonate). A cross-section of local geology at the B
Street Landfill is shown in Figure 3.
c. SOILS
Soils at Mountain Home AFB are typical of the entire plateau,
consisting mostly of wind-blown silt and sand.
Soil at
feet of
zones.
B Street Landfill consists of 0.5 to approximately 20
wind-deposited silt and sand with some caliche cemented
Disturbed areas contain varying amounts of refuse mixed
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT /11
-------
in with the soils, and several localized areas are overlain
large quantities of coal combustion ash from the coal-fired
on the Base.
by
plant
D.
HYDROGEOLOGY
The regional aquifer is in the Glenns Ferry Formation and the
Bruneau Formation. Groundwater occurs in the sedimentary
deposits and basalt flows of the formations. Wells in the Glenns
Ferry Formation yield up to 350 gallons per minute (gpm). Wells
in the Bruneau Formation yield from 10 to 3,100 gpm.
In the vicinity of Mountain Home AFB, regional groundwater flows
in a southerly direction toward the Snake River at a gradient of
about 1 foot per 200 feet. The principal recharge area for the
aquifer. underlying the Mountain Home Plateau is in the mountains
north of the plateau where precipitation infiltrates directly
into rock outcrops. A small amount of recharge is probably
provided by deep percolation of intermittent stream flow and
excess irrigation water.
Drinking water at Mountain Home AFB is obtained from nine Base
production wells completed in the Bruneau Formation (Figure 4).
The Base production wells range in depth from 379 feet to 610
feet bgs. The water table at the Base occurs at a depth of about
350 feet bgs. Calculations of aquifer transmissivities (rate of
water movement through the aquifer) for the Base production wells
result in values ranging from 65,000 to 650,000 gallons per day
per foot. An average yield of 1,094 gpm was calculated in 1987
from available well production data.
Within a 2-mile radius of the Base, about 35 private
been drilled, ranging from 300 to 700 feet in depth.
wells are downgradient (south) of the Base.
wells have
Several
Halls Ferry springs and Weatherby springs are both located about
2.5 miles south of the Base along the north canyon wall of the
Snake River. Both springs are discharge points for the regional
aquifer.
22835A/89MCl14H/R17 08-09-93(3:24pm)/RPT /11
-------
E.
SURFACE WATER HYDROLOGY
.~
The topography at the B Street Landfill is essentially flat,
exhibiting a maximum of approximately 20 feet of relief between
the shallow depressions and small topographic highs on the site.
These topographic features appear to be a result of site
trenching and dumping activities. Overall, the site is
topographically highest in the center and slopes off gently to
the east and southwest. No natural or man-made drainage features
are present at B-Street Landfill site, and precipitation either
infiltrates site soils or accumulates on the surface with
subsequent evaporation or infiltration. No sediments associated
with surface runoff are present at or adjacent to the landfill.
Most surface runoff on the Base drains via
the wastewater lagoons on the west side of
heavy rainfall, some excess stormwater may
Creek. However, surface runoff from the B
does not enter this drainage system.
a series of ditches to
the Base. During
be pumped to Canyon
Street Landfill site
F.
NATURE AND EXTENT OF CONTAMINATION
To identify the nature and extent of soil contamination at the B
Street Landfill, surface and subsurface soil samples were
collected and analyzed during the RI field investigation. soil
samples were collected at the Trench Area and Drum Disposal Area.
Samples at the Drum Disposal Area included ash and were used to
characterize the Ash Disp?sal Area.
Surface soil samples were not collected at the Rubble Area and
Burn Area because hazardous material disposal activities are not
suspected at these areas.
The results of the soil sampling are provided below. All metals
detected above background levels, and all organic compounds with
the exceptions noted in section VI A. that are discussed below
and in associated tables are included in the human health risk
characterization. The risk assessment evaluated whether the
concentration of contaminants found at the disposal areas pose a
human health risk and are of concern.
22835A/89MCI14H/RI7 OB-09-93(3:24pm)/RJYf /11
-------
1.
Trench Area
Suspected sources of contamination at the Trench Area are
industrial wastes, such as waste oils, solvents, or pesticides
that were probably poured over solid wastes in the landfill
trenches. General refuse was also placed in the trenches. The
wastes were reportedly burned prior to covering with soil on a
weekly basis, so that liquid wastes may have been partially or
completely combusted.
Nineteen soil samples were collected from nine test pits
excavated through Trenches 1, 2, 4, and 5. Prior to excavation,
surface soil samples were collected at each planned test pit
location. The pits were excavated across the width of the trench
and were dug to bedrock, to native soil beneath the rubbish zone,
or to the maximum reach of the backhoe (approximately 16 feet).
The samples were analyzed for volatile organic compounds (VOCs),
semivolatile organics, total recoverable petroleum hydrocarbons
(TRPH) , pesticides/PCBs, chlorinated herbicides, and total
metals. Chemical analytical summary tables showing detected
compounds are summarized in Tables 1 through 4. Sample locations
are shown in Figure 5.
Generally low levels of contamination were found in soil samples
from the trenches. Eight VOCs were detected in low
concentrations « 50 ~g/kg) in most soil samples. Maximum
concentrations of the eight VOCs are methylene chloride (49
~g/kg), toluene (14 ~g/kg), xylenes (8 ~g/kg), trichloroethane
(5 ~g/kg), 2-butanone (4 ~g/kg), tetrachloroethane (2 ~g/kg),
ethylbenzene (2 ~g/kg), and styrene (1 ~g/kg). Toluene,
trichloroethane, and xylenes were detected most frequently.
Frequency of detection and concentration ranges are listed in
Table 9.
Semivolatiles were detected in seven of the nineteen soil
samples. They were found more frequently in subsurface soils,
and particularly in the 8.5-foot-deep sample from test pit 5
(Trench 2). This sample contained several polycyclic aromatic
hydrocarbons (PAHs) up to 2900 ~g/kg, which may be evidence of
past burning of trash ~n the trench. Two other samples contained
22835A/89MC114H/R17 OB-09-93(3:24pm)/RPT /11
-------
-~
one PAH in a concentration above 2000 ~g/kg. In the remaining
samples, semivolatiles were either detected at 410 ~g/kg or less
(that is, at or below sample reporting limits), or were not
detected. Frequency of detection and concentration ranges are
listed in Table 10.
Total recoverable petroleum hydrocarbons (TRPH) were detected in
three of ten surface samples at concentrations between 104 and
155 mg/kg. The three samples were from Trenches 1 and 2. Three
subsurface soil samples collected from Trenches 1 and 2 also
contained TRPH in concentrations between 307 and 2,780 mg/kg
(Trench 1 samples) and 1,710 and 19,699 mg/kg (Trench 2 samples).
TRPH were not detected in soil samples from Trenches 4 or 5.
TRPH data is shown in Table 2.
Pesticides/PCBs were detected in both surface and subsurface soil
samples. Most results were estimated values below the sample
reporting limit. Table 11 summarizes occurrences of
pesticides/PCBs, along with the range of detected concentrations.
Trench 1 had the most frequent occurrence of pesticides/PCBs,
with the higher concentrations being detected below the ground
surface at depth.
The only pesticide detected in the soils
2,4-D. It was detected in three samples
ranging from 41 ~g/kg to 45,000 ~g/kg.
from the Trench Area was
in concentrations
Concentrations of metals in the surface soils at the Trench Area
were within background range, except for cadmium, lead, and
mercury. In subsurface soils, arsenic, cadmium, lead, mercury,
and zinc were found above background levels. Table 12 summarizes
metals of potential concern detected at the Trench Area.
In summary, generally low concentrations of organic compounds
were found erratically in surface and subsurface soil samples
from Trenches 1, 2, 4, and 5. One sample in Trench 2 contained
the highest concentrations of several PAHs, which could be
evidence of past burning of trash. No "hot spots" or localized
areas of contamination by hazardous substances were evident,
although pesticides/PCBs were detected more often in Trenches 1
22835A/89MC114H/R17 08..Q9-93(3:24pm)/RPT /11
-------
and 2 than in the other trenches. Concentrations of some metals
exceeded background concentrations. This pattern of
contamination supports the known history of the site as a
landfill for codisposal of general refuse and industrial wastes
that were burned and partially or entirely combusted prior to
covering with soil.
2.
Drum Disposal Area
The Drum Disposal Area is small (80 to 100 feet in diameter), and
the soil layer above bedrock is only about 1 foot thick, although
deeper piles of ash and debris are present in spots. Suspected
sources of contamination are drums that were placed on the soil
surface that may have contained hazardous substances and may have
leaked or spilled.
Fourteen shallow borings were drilled and sampled. Samples from
some borings were mixed to produce four composite samples for
analysis of semi volatiles , TRPH, pesticides/PCBs, chlorinated
herbicides, and metals. Six other samples were retained as
discrete samples for analysis of VOCs. Chemical analytical
summary tables showing detected compounds are summarized in
Tables 5 through 8. Sample locations are shown in Figure 6.
Analytical results from soil samples collected at the Drum
Disposal Area are summarized in Tables 5 through 8; sample
locations are shown in Figure 6. Bedrock is found at
approximately 1 foot below the native soil surface, and all
samples were collected at a depth of 0.5 to 1 foot below surface.
The soil samples collected contained approximately one-third
identifiable coal combustion ash that had been placed in the
area.
Five VOCs were detected in low concentrations «40 ~g/kg) (Table
5). Most reported results were estimated concentrations below
the sample reporting limit. Maximum concentrations of each are
methylene chloride (39 ~g/kg), toluene (33 ~g/kg), xylenes
(8 ~g/kg), trichloroethane (8 ~g/kg), and tetrachloroethene
(1 ~g/kg).
22835A/89MCl14H/R17 OS-09-93(3:24pm)/RPT /11
-------
,~
Several semivolatile compounds, mostly PAHs, were detected in the
four composite samples (Table 6). Reported concentrations ranged
from 40 ~g/kg (benzo(b)fluoranthene) to 1100 ~g/kg (fluoranthene
and benzo(b)fluoranthene). TRPH were detected in samples from
the center and southwest edge of the Drum Disposal Area.
The pesticides DDE and DDT were detected in the four composite
samples in concentrations ranging from 4 ~g/kg to 1300 ~g/kg, and
the PCB Aroclor 1254 was detected in two of four samples at 85
~g/kg and 240 ~g/kg (Table 7). These results may be evidence of
past storage of used drums at this site. No herbicides were
detected in Drum Disposal Area soils.
Several metals exceeded background concentrations. These are
arsenic, beryllium, cadmium, chromium, lead, mercury, and zinc.
The elevated metals concentrations probably result primarily from
the presence of coal combustion ash at the site, but some metals
such as lead, mercury, and zinc could result from past storage of
used containers with residues of industrial products such as POL
waste. Data are shown in Table 8.
3.
Ash Disposal Area
The Ash Disposal Area is approximately 1000 feet by 1000 feet and
contains both coal combustion ash and exposed soil (Figure 7).
Total volume of ash is estimated to be approximately 924,000
cubic feet, assuming an average depth of approximately 2 feet.
The ash was not directly sampled during the field investigation.
However, the soil samples collected at the Drum Disposal Area
were comprised of approximately one-third coal combustion ash.
Therefore, metals concentrations detected at the Drum Disposal
Area (Table 8) are considered representative of a soil/ash
mixture as is generally found throughout the Ash Disposal Area.
Supplemental samples of ash were collected after completion of
the RI by IDHW in January 1993. The results showed that metal
concentrations were approximately ten times lower than the metal
concentrations from the Drum Disposal Area that were used in the
RI to represent the Ash Disposal Area (Table 33).
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT 111
-------
G.
POTENTIAL ROUTES OF MIGRATION
Potential routes of off-site migration of contaminants from
source areas in the B Street Landfill are wind carrying
particulate matter from surface soils to off-site locations and
leaching of chemicals in surface and subsurface soils to
groundwater. People working at or visiting the landfill could
possibly be exposed to surface soils and wind-blown particulate
matter. There are no permanent surface water features or low
areas where water pools at the site. Normally, precipitation
either infiltrates or evaporates; therefore, surface runoff is
not considered a significant migration route.
H.
POTENTIALLY EXPOSED POPULATION
Mountain Home AFB is likely to remain a military installation in
the near future. The Base is undergoing a significant expansion
and is the first wing that will be assigned fighter, tanker, and
bomber aircraft. The B Street Landfill site will most likely
remain an industrial area while the Base is in operation and in
the event the Base closes. The B street Landfill site would
probably not attract residential development for the following
reasons: the presence of landfill trenches, the close proximity
to the runway and other industrial facilities, and the large
amount of solid debris (rubble), which would have to be removed
prior to construction on top of the landfill. The rubble is
expected to remain on-site at Base closure because there are no
State or Federal laws that require USAF to remove the rubble at
Base closure. Therefore, occupational/worker exposures under an
industrial scenario are an appropriate guide to potential risks
at the landfill under current or future use scenarios.
Under current use conditions, the landfill is inactive and
off-limits to all but authorized personnel. The workplaces
nearest the landfill are the Auto Hobby Shop, roughly 2,500 feet
southeast of the Trench Area; and the Munitions Storage Area,
roughly 500 feet east of the Rubble Area. The nearest residence
is on the Base, approximately 1 mile southeast of the landfill.
The landfill site is not fenced within the Base. Off the Base,
adjacent land use is agricultural. The landfill is fenced
.
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT /11
-------
.~
adjacent to farmland. The nearest off-Base resident is several
miles away. Therefore, exposure to contaminants from the B
street Landfill would be limited to trespassers to the landfill
(assumed to be Base employees or other workers) and nearby
workers or residents, who might be exposed by the air or
groundwater pathways.
In the future, the landfill will probably remain an inactive
industrial site while the Base is in operation and in the event
the Base closes. Commercial, residential, or agricultural
development is highly unlikely because of the proximity to the
main runway, the presence of the trenches, the large amounts of
rubble, and the availability of other land for development. In
addition, it is not likely that, landfilling activities will
resume because of the lack of available space for trench
disposal. Potentially exposed populations under probable future
use conditions are therefore, the same as under current use:
adult trespassers (workers) and off-site workers or residents.
Long-term on-site occupational or residential exposures are,
unlikely but are evaluated in the risk assessment to provide
upper-bound estimates of potential risk.
VI.
SUMMARY OF SITE RISKS
The baseline human health risk assessment in the RI report
evaluated potential risks to human health associated with
chemicals of concern detected in soils at the B street Landfill,
based on the assumption that no action is taken to remediate the
site. Human health risks were evaluated in accordance with EPA's
Risk Assessment Guidance for Superfund (RAGS) (EPA 1989a), RAGS
Part B (EPA 1991), and other regional and national EPA risk
assessment guidance.
The baseline human health risk assessment evaluated potential
risks associated with exposure to chemicals of concern in soil by
direct contact, air, and groundwater pathways at the Trench Area,
Drum Disposal Area, and Ash Disposal Area. Both carcinogenic
(cancer) risks and non-carcinogenic (toxic) hazards were
estimated for current and hypothetical future land use.
2283SA/89MC114H/R17 08-09.93(3:24pm)/RIYf 111
-------
Key steps in the risk assessment are outlined below.
A.
IDENTIFICATION OF CHEMICALS OF CONCERN
Potential chemicals of concern are those contaminants that may be
released to the environment from waste sources at the B Street
Landfill and that may pose health risks to humans exposed to the
contaminants. In this risk assessment, chemicals of concern were
all organic chemicals detected in one or more soil samples and
metals that exceeded background concentrations. Two semivolatile
organic compounds, phenanthrene and benzo(ghi)perylene, are not
included in the risk calculations because toxicity data are
inadequate for quantitative risk assessment. These compounds are
unlikely to contribute significantly to overall risk at the
sites. Chemicals of concern for each area are listed in Table
13.
B.
EXPOSURE ASSESSMENT
1.
Potentially Exposed Populations
Current Use Scenario:
Base employees (occupational receptors), who are assumed to work
at the landfill for 9 years or for 25 years, are the likely
population who could be directly exposed to chemicals at the B
Street Landfill. The average tour of duty at the Base is three
years, and the B Street Landfill is not a current work place.
Therefore, addressing long-term occupational exposures is a
conservative approach. Trespassers and nearby residents were not
evaluated because exposures and risks would be lower than for
on-site workers.
Future Use Scenario:
Humans who might be directly exposed to chemicals at the B street
Landfill if landfilling or other industrial activities resume
would be workers. Although future residential development of
the landfill is unlikely, hypothetical on-site residential
exposures to soils, air, and groundwater were also evaluated as
22835A/89MCI14H/RI7 OS-09-93(3:24pm)/RPT /11
-------
.~
an upper-bound estimate of risk under hypothetical maximum
exposure conditions. If unacceptable risks were not shown under
the residential scenario, then no exposure scenarios other than
on-site occupational and residential were considered because
exposures' and risks would be lower for other scenarios. However,
because a slight risk was shown under the upper-bound
hypothetical residential scenario at the Ash Disposal Area, a
trespasser, truck driver, recreational user, and landfill
fenceline resident were also evaluated as possible future
exposure scenarios.
Exposure pathways were evaluated for the following receptors:
Current Use Industrial Scenario:
.
Worker at the landfill
Future Use Industrial. Residential and Trespasser Scenarios:
.
Future worker at the landfill
Future on-site resident living on the
Future resident living at the edge of
Trespasser visiting the landfill
landfill surface
the landfill boundary
.
.
.
2.
Exposure Pathways
The exposure pathways for the Trench Area, Drum Disposal Area,
and Ash Disposal Area are listed below.
Trench Area Soils (Current & Future On-Site Occupational and
Future On-site Residential)
.
Ingestion of surface soils
Dermal contact with surface soils
Inhalation of volatile emissions and airborne
particulate matter
Ingestion of groundwater (future on-site residential
only)
.
.
.
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT /11
-------
Drum Disposal Area Soils (Current & Future On-site Occupational
and Future On-site Residential)
.
Ingestion of soils
Dermal contact with soils
Inhalation of volatile emissions and airborne
particulate matter
Ingestion of groundwater (future on-site residential
only)
.
.
.
Ash Disposal Area (Current & Future On-Site
On-site Residential. Future Trespasser. and
Residential)
Occupational. Future
Future Off-site
.
Ingestion of ash
Inhalation of airborne particulate matter
Ingestion of groundwater (future on-site &
residential only)
off-site
.
.
Ash Disposal Area (Truck Driver and Motorcyclist)
.
Inhalation of airborne particulate matter disturbed by
vehicle traffic
3.
Exposure Point Concentrations
Soils
Tables 14, 15, and 16 summarize the arithmetic mean and
reasonable maximum exposure (RME) concentrations for organic
chemicals and metals of concern in Trench Area surface soils and
in soils at the Drum Disposal Area and Ash Disposal Area. Mean
and RME soils concentrations were calculated using the data shown
in Tables 1 through 12. The RME concentration is the 95th
percentile upper confidence limit on the arithmetic mean
concentration. It is the reasonable maximum estimate of the
chemical concentration at the site and is used in evaluating
reasonable maximum risks due to exposures to soils at the site.
At the Trench Area, only results from surface soil samples were
used to estimate exposure concentrations for soil and air. Both
22835A/89MCl1411/R17 08-09-93(3:24pm)/RPT/ll
-------
surface and subsurface samples were used in estimating source
concentrations for the groundwater pathway (Table 17).
.D
Air
Mean and RME soil concentrations were used to model mean and RME
exposure point concentrations of chemicals of concern in air.
Modeled air concentrations from chemicals of concern in soils are
shown in Tables 14, 15 and 16.
RME air concentrations of respirable dust particles (particulate
matter less than 10 ~m in diameter, PM10) were estimated using
wind erosion modeling procedures recommended in EPA 1991c.
Volatilization of VOCs from surface soils and dispersion at the
site were evaluated using air dispersion models recommended in
EPA's Superfund Exposure Assessment Manual (SEAM, EPA 1988).
Groundwater
The hydrogeology at the Base is complex and is not fully
characterized. A base-wide groundwater study is being conducted
in OU 3. At this time, it is not known if the existing
monitoring well network is adequate to characterize potential
groundwater contamination from the landfill. au 3 will address
whether additional monitoring wells are required to evaluate
potential groundwater contamination.
Therefore, a conservative chemical fate and transport model was
used to estimate the potential risk to groundwater from
contaminants remaining in soils at the landfill disposal areas.
The model estimates concentrations of chemicals that may have
leached from soils at the disposal areas and migrated down to
groundwater. The model is very conservative and generally tends
to overpredict rather than underpredict actual concentrations of
contaminants in groundwater.
Modeled concentrations of chemicals of concern in groundwater
from each source area are shown in Tables 17, 18 and 19. In
these tables, modeled concentrations in groundwater are compared
to health-protective risk-based concentrations (RBCs) for
22835A/89MCI14H/RI7 08-09-93(3:24pm)/RI'T/ll
-------
residential USL to evaluate the potential for adverse health
impacts via ingestion of groundwater. Chemicals that exceed RBCs
are included in the quantitative risk assessment. Modeled
concentrations of all chemicals except arsenic were below RBCs by
factors of 10 to 10,000,000, and therefore, are not of concern
for adverse health effects. The modeled arsenic concentrations
at the Trench Area, Drum Disposal Area, and Ash Disposal Area
were 0.256 ~g/L, 5 ~g/L, and 15 ~g/L, respectively, and are
evaluated in the quantitative risk assessment.
'''(
It should be noted that analysis of groundwater samples from the
existing monitoring. wells at the B street Landfill and of Base
drinking water wel~s has not detected concentrations of arsenic
above background. However, these results cannot be used as
conclusive evidence of the absence of landfill leaching until
completion of the groundwater investigation in au 3.
4.
Chemical Intake by Exposure Pathway
Chemical intakes for each exposure pathway were calculated based
on the exposure point concentrations of chemicals of concern and
other exposure parameters, such as body weight, inhalation rate,
soil ingestion rates, dermal absorption rates, soil matrix
effects, and frequency and duration of exposure. Chemical
intakes were estimated in accordance with EPA's guidance Risk
Assessment Guidance for Superfund (EPA 1989a), Exposure Factors
Handbook (EPA 1989b), and Standard Default Exposure Factors (EPA
1991a). The results of this step of the risk assessment were
estimates of chemical-specific intakes in terms of milligrams
chemical per kilogram body weight per day (mg/kg-day).
Site-specific average (average) risk estimates were calculated
using reasonable best estimates. Site-specific RME and standard
default RME risk estimates were calculated using conservative
(health-protective) best estimates of probable exposures at the
landfill under the various exposure scenarios. Average and site-
specific RME risk calculations assumed that long-term
occupational or residential exposures would occur only if
construction occurred at the landfill. Therefore, grading,
filling, paving, landscaping, and other construction activities
"
22835A/89MCl14H/RI7 08-09-93(3:24pm)/RPT III
-------
would reduce the amount of exposed contaminated soil by at least
one-half. Average and site-specific RME occupational scenarios
also assumed an exposure time of 2 to 4 hours/day, 120 or 250
days/year for 9 years or for 25 years. The average risk
calculation included a soil matrix effect to account for the
reduced chemical dose resulting from chemical adsorption to soil.
The average risk calculation also included the effects of cold
weather and snow cover that reduce time spent outside and direct
contact with soil during winter. Standard default RME risk
estimates were calculated using EPA Standard Default Exposure
Factors (SDEFs) (EPA 1991a). SDEFs are a set of default
exposures values for use in exposure assessments when site-
specific exposure data are lacking. Exposure assumptions for
average, site-specific RME, and standard default RME scenarios
are shown in Tables 20 through 25.
C.
TOXICITY ASSESSMENT
The toxicity assessment addresses the potential for a chemical of
concern to cause adverse effects in exposed populations and
estimates the relationship between extent of exposure and extent
of toxic injury (dose-response relationship) for each chemical.
Qualitative and quantitative toxicity information for the
chemicals of concern is acquired through evaluation of relevant
scientific literature. The most directly relevant data come from
studies in humans. However, most of the useable information on
the toxic effects of chemicals comes from controlled experiments
in animals. The result of toxicity assessments performed by EPA
is the development of chemical-specific toxicity factors for the
inhalation and oral exposure routes. These toxicity factors are
published in the Integrated Risk Information System (IRIS) and
the Health Effects Assessment Summary Tables (EPA 1992).
EPA toxicity factors are used to assess potential health risks
resulting from the estimated chemical intakes. Toxicity factors
are expressed either as Reference Doses (RfDs) for
noncarcinogenic compounds or cancer slope factors (SFs) for
carcinogens.
22835A/89MClI4H/R17 08-09-93(3:24pm )/RPT /11
-------
RfDs are used to estimate the potential for noncarcinogenic
(toxic) effects of substances. A RfD is the daily dose of a
noncarcinogen that is not likely to result in toxic effects to
humans over a lifetime of exposure. RfDs are derived from human
epidemiological studies or animal studies to which safety factors
have been applied (e.g., to account for the use of animal data to
predict effects in humans). RfDs are expressed in units of mg
chemical/kg body weight/day. Estimated daily chemical doses from
exposure to contaminated media are compared to the RfD to
estimate the potential for toxic effects.
'-j
I
Slope factors (SFs) have been developed by EPA for estimating
excess lifetime cancer risks associated with exposure to
potential carcinogens. SFs, which are expressed in units of
(mg/kg-day)-l, are multiplied by the estimated daily dose of a
potential carcinogen, in mg/kg-day, to provide an upper-bound
estimate of the excess lifetime cancer risk associated with
exposure at that dose 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
highly unlikely. Slope factors are derived from the results of
human epidemiological studies or chronic animal studies, which
applies mathematical extrapolation from high doses to low doses
(e.g., to account for the use of animal data to predict effects
on humans). RfDs and SFs for each chemical of concern are
presented in Table 26 and Table 27.
D.
RISK CHARACTERIZATION
The risk characterization combines the outputs of the exposure
and toxicity assessments to develop quantitative estimates of
health risks associated with the site. Noncarcinogenic health
risks are characterized by comparing the estimated daily chemical
dose to the RfD. The ratio of the estimated dose to RfD is
called a hazard index. Hazard indexes are added together for all
chemicals and exposure pathways to yield a total hazard index for
the combined exposures. A hazard index equal to or less than 1
indicates that no adverse noncarcinogenic health effects are
expected to occur, even to sensitive individuals over a lifetime
of exposure.
2283SA/89MCl141-1/R17 08-09-93(3:24pm)/RPT III
-------
.~
carcinogenic health risks are characterized as the excess
probability (for example, 1 in 1,000,000) that an individual will
develop cancer due to the estimated exposure. Excess probability
means the increased risk over and above the normal risk of
getting cancer. Cancer risks are calculated by multiplying the
estimated daily chemical intake by the chemical-specific cancer
slope factor. Cancer risks are calculated separately for each
carcinogen and each exposure pathway, and then added together to
yield a total upper-bound estimate of cancer risk due to the
combined exposures. This is a highly conservative approach,
which makes underestimation of the actual cancer risk unlikely.
EPA has established an acceptable target excess cancer risk range
of 1 x 10-6 to 1 X 10-4 (1 in 1,000,000 to 1 in 10,000) as
guidance for protection of public health from exposure to
chemicals released from hazardous waste sites (EPA 1989a). An
excess lifetime cancer risk of 1 x 10-4 indicates that an
individual has a one in ten thousand chance of developing cancer
over a lifetime of exposure to site-related carcinogens.
Human Health Risk Characterization
1. Current and Future Use occupational Risk Estimates
occupational health risk estimates for the three sites at the B
Street Landfill are shown in Table 28. Risk estimates are shown
in this and other tables using scientific notation, e.g., 1E-06.
The number 1E-06 is equivalent to 1 x 10-6 or 0.000001 (1 in
1,000,000). The greatest risks were shown for long-term
exposures at the Ash Disposal Area under standard default
reasonable maximum exposure (standard default RME). The total
hazard index for this scenario is 0.2. A hazard index of 1 or
pelow indicates that no adverse noncarcinogenic health effects
are expected under the assumed exposure conditions. The total
excess cancer risk is 3.5 x 10-5 (3.5 in 100,000), which is
within EPA's target risk range of 1 in 1,000,000 to 1 in 10,000.
occupational risks estimated for exposures at the Trench Area and
Drum Di~posal Area are lower than those found at the Ash Disposal
Area. These results show that no unacceptable health risks are
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT III
-------
expected to occur to workers from daily, long-term (25 years)
exposure at any of the three sites at the B street Landfill.
exposure assumptions are extremely conservative, and it is
unlikely that the estimated risk level would be exceeded under
any likely exposure conditions.
The
-r
;
2. Future Use Residential Risk Estimates
On-site residential risks were calculated as upper-bound
estimates of risk. On-site residential health risks at the three
sites are shown in Table 29. These scenarios assume that a
family lives in a house built on the landfill surface, which is
very improbable because the Base is expected to remain an active
USAF installation or industrial site. Furthermore, residential
or commercial development of the landfill is unlikely because of
the presence of the trenches and Rubble Area, and the proximity
to the main runway. Therefore, risk estimates for residential
exposures are not likely risks at the landfill.
At the Trench Area, the maximum residential hazard index is 0.8
and the maximum total cancer risk estimate is 1 x 10-5 (1 in
100,000) under the standard default RME. The hazard index below
1 indicates no adverse noncarcinogenic health effects are
expected, and the cancer risk estimate is within EPA's target
risk range. Therefore, no unacceptable risks are expected to
occur at the Trench Area, even using highly conservative
residential exposure scenarios. It is unlikely that these risk
levels would be exceeded under any likely exposure conditions.
At the Drum Disposal Area, the maximum residential hazard index
is 0.7. The hazard index does not exceed 1, indicating that no
adverse noncarcinogenic health effects are expected to occur
under residential exposure scenarios and conservative assumptions
of toxicity. The total excess cancer risk estimates are
3.2 X 10-6 (average), 1.7 X 10-4 (si te-specif ic RME), and
2.4 x 10-4 (standard default RME). The total excess cancer risk
estimates under the site-specific RME and standard default RME
are somewhat above the upper end of EPA's target risk range of
10-6 to 10-4. Nearly half the estimated cancer risk estimates
22835A/89MCI14H/RI7 08-09-93(3:24pm)/RPT /11
-------
under site-specific RME and standard default RME exposure
assumptions results from ingesting modeled concentrations of .
arsenic in groundwater. However, the modeled concentrations may
be overpredicted and 5 to 50 times higher than actual on-site
concentrations because of the conservative assumptions used in
the groundwater model (see Table 32). In addition, on-site
residential cancer risk estimates and hazard indexes are not
considered representative of potential exposures and risks at
this site for the following reasons: many exposure and toxicity
factors used in the risk estimate tend to overpredict risk;
residential development is unlikely; and the Drum Disposal Area
is small, with very shallow bedrock that would not be suitable
for construction. The assumed exposure conditions are very
conservative, and it is unlikely that these risk levels would be
exceeded under any likely exposure conditions.
At the Ash Disposal Area, where chemicals of concern are certain
metals, residential hazard indexes are 0.05 (average), 0.8 (site-
specific RME), and 1.6 (standard default RME). Only the standard
default RME hazard index exceeds 1, indicating a potential cause
for concern for noncarcinogenic health effects. However, the
standard default RME hazard index overestimates the potential
hazard, because it assumes that low doses of chemicals that are
not toxic in themselves produce a toxic effect in combination.
The assumption that the chemicals produce a toxic effect in
combination is used as a screening tool. If the combined HI is
greater than 1, it is appropriate to consider the effects of each
chemical on target organs separately and then determine whether
they should be combined. At the Ash Disposal Area, the metals
that contribute most to the noncarcinogenic hazard index are
arsenic, barium, and zinc. None of the metals alone is expected
to produce a toxic effect because the daily doses of each metal
are below the respective RfDs. These metals may not produce a
toxic effect in combination in the body because these metals
affect different organs in the body. Also, the childhood
ingestion rates could be lower by 2 to 5 times than those used in
the risk calculations (Calabrese et ale 1989; Davis et ale 1990).
Note that Calabrese's work is still under review by EPA.
Therefore, the hazard indexes overpredict the potential for
22835A/89MC11.UI/RI7 08-09-93(3:24pm)/RPT /11
-------
adverse health effects, and it is unlikely that the risk levels
would be exceeded under any likely exposure conditions.
"'-
""
On-site residential total cancer risk estimates at the Ash
Disposal Area are 1 x 10-5 (average), 5 x 10-4 (site-specific
RME), and 6.5 x 10-4 (standard default RME). The site-specific
RME and standard default RME cancer risk estimates exceed EPA's
target risk range of 10-6 to 10-4. At least half of the total
cancer risk estimates (3.1 x 10-4) derives from risk associated
with ingestion of groundwater containing a modeled on-site
concentration of arsenic of 15 parts per billion or micrograms
per liter (ppb or ~g/L). The estimated concentration may be
overpredicted by 5 to 50 times (see Table 32). Also, there is
uncertainty in the source concentration of arsenic in the ash, as
indicated in Section F.3. Metal concentrations in ash could be
ten times lower than the source concentration used in the risk
assessment and groundwater model. The estimated modeled
concentration of 15 ppb is below the Federal Drinking Water
Standard, Maximum Contaminant Level (MCL) of 50 ppb. However,
the MCL is currently under review by EPA and may be lowered. On-
site residential cancer risk estimates and hazard indexes are
highly unlikely.
3.
other Future Use Exposure Scenarios: Ash Disposal Area
On-site residential use is highly unlikely, and the B Street
Landfill is likely to remain a disposal site without significant
construction (and may remain inactive). Further, actual risks
under a probable exposure scenario would be lower than those
estimated for long-term on-site residential use. Recognizing
these factors, five other more reasonable but still conservative
future use exposure scenarios at the Ash Disposal Area were
evaluated to support the remedial decision for this site. The
five scenarios are:
.
Off-site residential exposures to groundwater (landfill
fenceline)
Child trespasser (ash ingestion)
.
2283SA/89MC114H/R17 OS-09-93(3:24pm)/RPT 111
-------
.
~ .
.
Landfill truck driver (inhalation of airborne ash and
soil)
Recreational motorcyclist (inhalation of airborne ash
and soil)
Off-site downwind residential receptor (ingestion of
ash deposited from airborne ash)
The location of the hypothetical resident at the landfill
fenceline is shown in Figure 7. Risk results for these scenarios
are shown in Tables 30 and 31. Table 30 shows that the risk from
ingestion of groundwater with modeled concentrations of arsenic
at 11 ppb at a residential well at the landfill boundary
(fenceline) is 2 x 10-4. However, the modeled concentration of
arsenic at the landfill boundary may be overpredicted by 5 to 100
times (see Table 23). Further, the arsenic concentration in ash
may also be overestimated (see Section F.3). If arsenic
concentrations were lower by 5 to 100 times, arsenic
concentrations would range from 3 to .15 ppb, and cancer risk
estimates would range from 6 x 10-5 to 3 X 10-6. In addition,
estimated groundwater concentrations decrease with distance
downgradient from the landfill. For example, the estimated
concentration and associated risk at the downgradient Base
boundary (2,500 feet southwest) is 2.6 ppb and 5 x 10-5. The
Base boundary is a more probable location for a future resident
if the runway continues to be used and the rubble remains in
place. Therefore, considering the conservatism of the source
concentration and the groundwater model and the most probable
location for a nearby resident, the cancer risk estimate is
within EPA's target risk range and shows that no unacceptable
risks would probably be associated with exposure to groundwater
at the landfill or Base boundary.
Risks to off-site residents from inhalation are considered
insignificant because on-site risks from inhalation were
negligible. Soil ingestion risks to the off-site resident from
airborne ash deposited in soils beyond the landfill fenceline are
also insignificant. If only wind erosion (no traffic) occurs
over the ash, the ash source is likely to be depleted before
airborne deposits beyond the landfill would reach concentrations
that could pose a risk. Even if daily heavy truck traffic
22835A/89MCI14H/R17 08-09-93(3:24pmJ/RlYf /11
-------
occurred over the ash piles, which is highly unlikely, metals of
concern would pose soil ingestion risks slightly in excess of
EPA's target risk range.
. Table 31 shows the risk results for the child trespasser,
landfill truck driver, and recreational motorcyclist. The
highest excess cancer risk estimate is 1.6 x 10-5 (child
trespasser, 6-year exposure). This risk level is within EPA's
target risk range. Risks for other scenarios were lower.
The highest hazard index shown in Table 31 is 1.1 (landfill truck
driver, 25-year exposure). This value is slightly above 1 and
indicates little or no cause for concern for adverse
noncarcinogenic effects. Also, the magnitude of the hazard index
is due entirely to chromium. The RfD used to assess chromium
inhalation toxicity is derived from exposures to chromic acid
fumes, rather than particulate-adhered chromium. Therefore, the
RfD probably overestimates actual toxicity of chromium adhered to
soil or ash particles, and the hazard index of 1.1 probably
overestimates the potential for noncarcinogenic effects. In
summary, there does not appear to be cause for concern for
adverse noncarcinogenic health effects from exposures at the Ash
Disposal Area for the following reasons: the value is not
significantly different than 1; the conservative toxicity value
used probably results in an overestimation of potential hazard;
and the daily exposures for 25 years probably overstates likely
exposure at the site.
4.
Exposures to Lead
Effects of potential exposures to lead in soil were evaluated by
comparing maximum lead concentrations to values recommended by
EPA. Current EPA guidance recommends an interim soil lead
concentration of 500 to 1,000 ppm (mg/kg) for residential sites.
The maximum lead concentration measured in surface soil samples
at the Trench Area was 79 mg/kg. The maximum lead concentration
measured at the Drum Disposal Area was 133 mg/kg. The estimated
reasonable maximum lead concentration in the ash was 383 mg/kg.
These concentrations fall below the range recommended by EPA for
residential exposures. Therefore, lead concentrations in soils
22835A/89MCI14H/RI7 08-09-93(3:24pm)/RPT /11
-------
~
at these sites do not pose unreasonable risk to occupational or
residential receptors.
E.
HUMAN HEALTH RISK CHARACTERIZATION SUMMARY
.
The B street Landfill will most likely remain as an
industrial site both while the Base is in operation and if
the Base closes. Therefore, industrial use is the probable
current and' future use of the site.
.
Human health risks for long-term occupational exposures to
soils and ash at the B street Landfill do not exceed target
risk levels (hazard indexes do not exceed 1 and cancer risk
estimates are within EPA' s target risk range of 1 x 10-4 to
1 x 10-6).
.
Other potential receptors under an industrial scenario
include a hypothetical nearby resident. For the nearby
resident, risks from ingestion of a modeled concentration of
arsenic in groundwater at the landfill boundary is 2 x 10-4.
This risk estimate is the same order of magnitude as
1 x 10-4. The modeled concentration of arsenic at the
landfill boundary may be overpredicted by 5 to 100 times. If
arsenic concentrations were 5 to 100 times lower, estimated
cancer risks would range from 6 x 10-5 to 3 X 10-6. In
addition, the modeled concentration of 11 ppb at the
landfill boundary is below the Federal Drinking Water
Standard, MCL for arsenic of 50 ppb. However, the MCL is
currently under review by the EPA and may be lowered.
Estimated concentrations of arsenic continue to decrease
downgradient from the landfill and the estimated risk at the
Base boundary is 5 x 10-5. The Base boundary is a more
probable location for a future resident if the runway
continues to be used.
.
Risks posed to trespassers are also within EPA's acceptable
target risk levels.
22835A/89MC114H/RJ7 08-09-93(3:2.tpm)/RPT /11
-------
.
Estimated total risks for the future on-site residential
scenario, which is an unlikely scenario, are within EPA's
target risk range at the Trench Area. Total risks at the
Drum Disposal Area and Ash Disposal Area slightly exceed
EPA's target risk range. However, the conservatism in the
groundwater model and derivation of estimated metal
concentrations at the Ash Disposal Area from a soil/ash
mixture at the Drum Disposal Area may overpredict risk
estimates.
f
.
In conclusion, current or reasonable maximum industrial
(occupational) future use of the landfill pose no
unacceptable risks. Hazard indexes and cancer risks do not
exceed EPA's target levels, assuming long-term on-site
occupational exposures, and nearby resident at the Base
fenceline and trespasser exposures.
F.
UNCERTAINTY
uncertainties in this risk assessment are associated with the
estimates of exposure point concentrations and the assumptions
regarding human exposure scenarios. Conservative assumptions
were used so that risks would not be underestimated. Persons
were assumed to be directly exposed to reasonable maximum
concentrations of chemicals of concern in soil and ash for up to
30 years. Hypothetical residents were assumed to be exposed to
modeled worst-case concentrations in groundwater for 30 years.
The screening-level groundwater transport model results in
concentrations that may overestimate actual concentrations by
5 to 50 times at the B street Landfill and 5 to 100 times at the
B street Landfill boundary (see Table 32). Therefore, the model
may overstate the concentrations to which individuals may be
exposed.
Conservative assumptions were also used in the estimated
concentration of arsenic at the Ash Disposal Area. Based on
soil/ash samples at the Drum Disposal Area, a concentration of
106 ppm arsenic was used for the ash ingestion risk
characterization, and 38 ppm was used as a soil/ash source
concentration of arsenic for groundwater modeling. However,
22835A/89MClI4H/R17 08-09-93(3:24pm)/IU'T /11
-35-
-------
'0
supplemental analysis of ash samples collected by the state of
Idaho showed the maximum concentration of arsenic to be 6.5 ppm.
Therefore, exposure point concentrations may be overpredicted.
~
.
The ingestion rates, inhalation rates, and exposure times used in
estimating daily intakes were also conservatively high and are
not likely to be exceeded. Toxicity factors used to assess
potential human health risks were conservative because they are
derived from conservative estimates of dose-response
relationships observed in laboratory animals. These estimates
included safety factors to account for the uncertainty in
extrapolating from experimental results in laboratory animals to
lifetime exposures of humans.
Some uncertainty is associated with exposure point concentrations
and risk estimates for the Trench Area because a limited number
of samples (19) were collected from the four trenches
investigated. The sample results are assumed to be
representative of contamination at the trenches. However,
because the waste is heterogeneous, the sample results could
underestimate or overestimate contaminant concentrations in the
trenches as a whole. Therefore, risks could be underestimated or
overestimated. However, other conservative features of the
analysis, such as assuming long-term exposures, using reasonable
maximum estimates of contaminant concentrations and
health-protective toxicity factors, help offset the uncertainty
in the sampling results to provide reasonable maximum estimates
of risk.
There is also uncertainty about whether additional trenches are
present at the Rubble Area. Historical records do not confirm
their presence in the Rubble Area. However, if any refuse and
hazardous wastes were disposed in the Rubble Area, it is likely
to have been similar to the wastes disposed in the Trench Area.
The results of the risk assessment provide an upper-bound
estimate of potential risk under long-term occupational and
residential exposure conditions. The results indicate that
exposures to soils, groundwater, and air at the landfill source
areas are not likely to have adverse effects on health of
22835A/89MCl14H/RI7 08-09-93(3:24pm)/RI'T/11
-------
individuals working at the landfill or to individuals residing at
the landfill boundary.
~r
G.
LIKELIHOOD OF ADVERSE ECOLOGICAL EFFECTS
The B street Landfill is a sparsely vegetated area, covered with
native soil, ash, rubble, and fill material. Small mammals
(coyote, rabbit, rodents) and lizards have been observed at the
area. Field observations were conducted during the course of the
remedial investigation and during a site reconnaissance by an
ecologist in September 1992. Information on common species in
the area and on federal and state protected species was gathered
from literature and from state and federal agencies. The
landfill does not provide significant habitat for threatened or
endangered species or other species of special concern. This
conclusion is based on field observations, information on federal
and state protected species, and availability of alternate
habitats. Therefore, the potential for adverse ecological
effects is considered minimal.
Potential impacts to ecological receptors from the B-Street
Landfill will be addressed in more detail as part of a base-wide
ecological risk assessment in the final OU (OU 3).
VII.
SELECTED REMEDY
USAF, EPA and IDHW have determined that no remedial action is
necessary under CERCLA at the B Street Landfill to ensure
protection of human health and the environment. This decision is
based on the results of the baseline human health risk assessment
and ecological evaluation, which determined that the chemical
concentrations remaining in the soils at the B Street Landfill
pose no unacceptable risks to human health and the environment
under current and probable reasonable maximum future use
scenarios. Due to uncertainties with the assumptions used in the
groundwater model, the OU 3 base-wide groundwater investigation
and verification will address whether monitoring is needed at the
B Street Landfill.
22835A/89MC114H/R17 08-09-93(3:24pm)/RI'T /11
-------
However, the no action remedy may result in hazardous substances
remaining on-site that do not allow for unlimited use and
unrestricted exposure because there are uncertainties associated
with the risk assessment at the Trench Area due to the number of
samples collected, the heterogeneous nature of the wastes, and
the possibility of trench disposal in the Rubble Area. Therefore,
a statutory 5-year review of the site will apply.
The 5-year review will evaluate whether the no action remedy
remains protective of human health and the environment. The
5-year review will consist of a Level I review, as described in
the structure and Components of Five-Year Reviews, by Henry L.
Longest II, Director, Office of Emergency and Remedial Response,
May 23, 1991, and subsequent guidance. Generally the Level I
review will consist of an ARARs review for new standards or
regulations, and a site visit to verify that residential
development on top of the trenches is not likely and that
intrusion into the trenches has not occurred.
state Acceptance
The state of Idaho concurs with the CERCLA evaluation, and the
Air Force has agreed to address state solid waste laws in
accordance with Air Force letter dated May 7, 1993,
Subject: Submittal of Closure Plan for B street Landfill.
VIII.
EXPLANATION OF SIGNIFICANT CHANGES
The Proposed Plan for the B Street Landfill site was released for
public comment on January 26, 1993. The Proposed Plan identified
No Action as the selected remedy for the site. Public comments
on the Proposed Plan were evaluated at the end of the 30-day
comment period, and it was determined that no significant changes
to the Proposed Plan were necessary.
.'
22835A/89MCI14H/RI7 08-09-93(3:24pm)/RI'T /11
-------
RESPONSIVENESS SUMMARY
B STREET LANDFILL
The public comment period on the Proposed Plan was held from
January 26, 1993, to February 25, 1993. A public meeting was
held on February 11, 1993, to explain the Proposed Plan and
solicit public comments. Several questions were asked during the
public meeting. Some of these questions were also provided in
writing during the public meeting and are included in Appendix B.
This summary is a response to the written and verbal comments
received during the public comment period.
1.
Why does the State not concur or accept the validity of the
data, and why is the state asking for "action" at the site
under Title 1 Chapter 6 of the Idaho Solid Waste Management
Regulations and Standards Manual?
Response:
The state of Idaho's (State) requirement for compliance with
Title 1, Chapter 6 Solid Waste Management Regulations does
not constitute a rejection of the RI or the data presented
in the RI. Under state law, these requirements apply to all
municipal solid waste landfills that were operated in Idaho
from 1973 to October 1991.
2.
Is it wise to pose an unnecessary additional burden on the
tax payer of $ 1.1 million to cap the site as the manual
requires for current operating landfills and the state
funding through the Defense state Memorandum of Agreement
(DSMOA)? These burdens are assumed by the tax payer.
Doesn't the evidence support "no action".
Response:
The State requirement for Air Force compliance with Title 1,
Chapter 6 does not constitute a CERCLA action. Again these
requirements apply to all municipal solid waste landfills
operated between 1973 and 1991. The Trench Area is not
su?ject to this requirement because it ceased operation and
22835A/89MC114H/R17 08-09-93(3:24pm)/RPT /11
-------
closed in 1969. The state concurs with the no action
decision for both the Trench Area, Drum Disposal Area and
Ash Disposal Area at the B street Landfill under CERCLA.
However, it is the state's position that the state municipal
landfill closure requirements are still applicable to the
landfill independent of CERCLA decisions.
The closure will not be funded as a CERCLA action,
therefore, the state is not eligible for DSMOA funding. In
addition, the state has not received a cost estimate from
the Air Force for capping the landfill at $ 1.1 million.
3.
What specific additional actions (burden on the tax payer)
is the state requiring the Air Force to perform to comply
with Title 1, Chapter 6 of the Idaho Solid Waste Management
Regulations and Standards Manual? Is the State asking for
capping of the site or installation of additional monitoring
wells and groundwater monitoring beyond the au 3
investigation and 5 year review or some other action?
Response:
No additional action is being required at the Trench Area.
The decision on the need for long term groundwater
monitoring at the B street Landfill has been deferred to
OU 3. The Central District Health Department will determine
which areas of the B street Landfill will be addressed and
what actions will be required under the closure plan. It is
anticipated that only the Ash Disposal Area and possibly the
Drum Disposal Area will be subject to the municipal landfill
closure requirements. The Air Force will be required to
meet the state solid waste landfill closure requirements.
22835A/89MC1l4H/R17 08-09-93(3:24pm)/RPT III
-------
4.
One citizen commented on the difficulty of finding the room
in the high school for the public meeting.
-/
Response:
The Air Force, EPA and the state apologize for the
difficulty in locating the room. A sign was posted
gym doors identifying the room number.
on the
'.
~
22835A/89MCl14H/R17 OS-09-93(3:24pm)/RPT III
-------
APPENDIX A
FIGURES AND TABLES
-------
MOUNTAIN
HOME
MOUNTAIN HOME
AIR FORCE BASE
ELMORE
COUNTY
C.J. STRIKE
RESERVOI R
e~U.
~/"'~~~4V
" -
OWYHEE COUNTY
IDAHO
.
VIC I N ITY
MAP
AREA LOCATION
o
,
2
3 4
8
.
DIItC. 1'1': SCR
~ 8'1': se,.,
1)1.1'[. 12 - 4 - 92
3-Z.-4f 3
FIGURE NO.:
SCALE IN MILES
-------
. :1
. .
~
LEGEND
A
c:=J
MONITORINO WELL LOCATION
DISPOSAL TRENCH
,
BACKtiOE
PIT
o
250
500
1000
1500
Woodward-Clyde Consultants
tNGltlttRING L SCI[NC£S AF'PUtD
10 111£ [ARm, IT S [/IVIROtIHbn
.
SCAt£ IU r [[ T
IF-02 "REI\ MI\P
1G. NO
-------
3000
..J
VJ
~ 2000-
G)
>
o
1i
r. 2000-
G)
IL
~
o
:j1
u
~ 2700-
fj]
2600
MW-4
MW-2
MW-5
lnndrm
JOOO
:,:' ------ -I- ------------ "
'.,:' I:,: :,:'
~ .~ ~
. . .. . .,
:':, ,:". '-..
:". ,~: I:,
~ ~~.
} ~ -----------.
~'-------:::::::::::::::f::::------------I-
'~,: -------- ".,: .,:'
:,:, ".f ',:'
'.,:' ".( .,:'
'.,,1 ':f I:'
----------------------- ,.,
': ---------------------- --------- . '.,
.t. .. .1. .-------- -----.. "l
f'----------------------- ~. ---------::===: ~
. . .---------------------- ,:. --------------- f"
., +
10/20/81 .n.. ".,: 0I/'I5/81.n.. I:'
".(,:'
..J
VJ
- 2900 ~
.,
>
o
1l
- 2000 ~
.,
11..
- 2700
t:
o
:p
u
>
.,
i~
10/24/81
2600
1000
,
LEGEND
l!ti::1 DaBoll
~ DOBail and Sand/Shalo
~ftI Zonos Identified by Holurol
~ Gamma logs
L - .2J0
Feet
Ilorizontal Scale
Vortlcnl Exaggerotlon= 4X
~ Sill and Sand
.u. Water level and Dato Measured
- - - Uncerlaln Lithologic and Geophysical
Correlations
..
Woodward-Clyde Consultants ~
ENCINEERIIIC . SCIENCES APPUEO -
'0 mE EAR 11. . 115 ENVlRONIAEN' ~
SOURCE: DAMES AND MOORE. 1990
GEOLOGIC CROSS-SECTION-B STREET LANDFILL
MOUNTAIN HOME AFB, IDAHO
DATE ArRll 1992 PROUCT 110.
DATE APRil 1992 891.fCI14H
DRN BY
CHICO BY
lC. NO
-------
N 2 .
LANDFILL ~NDFILL)
~ (B STREET
'\ MW-3
\
MW-16
~
l
t-~I
/
MOUNTAIN H~~E
AFB BOUNDA
".
""'"
"'. ..'==-s
".,,-,,,,., -=-
;;:;-
0>
I
If")
N
I
n
.2.
/
I
I
I
/
I
j
J
-
"
2000
1000
SCALE IN FEET
o
2000
,
!
~
I
d-Clyde
Woodwar,>NCES APP!..!E~T
EIJGINEERINGTl;& ;~TS ENVIRO~IM~N
TO THE EAR 2 AREA AND
LANDFILL No. LOCATION MAP
WATER WELLME AFB IDAHO
MOUNTAIN HO PROJECT NO,
CJG DATE: 03/24/93 89MC114H
DRN BY: ~t\II REI;lSJON: 0
CHK'D BY
~
~
...
0>
OJ
LEGEND WELL LEVEL MONITORING
RCHED ZONE TH NO WATER
L PE RING WELL WI
A M~;t~RODUCTION :;~~L DATALOGGER
: ~ONITORING WELL
w
::d
...
c
..:
-------
CAD rilL MIIAFB-15.DWG (10-02-92)
~
~
"0
~o-
*.
"0
"".~
LEGEND
~
A
001
~
~f!P ""
MONITORING WELL (WITH DATALOGGER)
MONITORING WELL (WITH USGS RECORDER)
WCC TEST PIT WITH DESIGNATION No.
SURrACE CONTOURS
..00 200
~
SCALE IN HET
o
400
1 .
~ Woodward-Clyde Consultants ~
f?-:) ENGINEERING & SCIENCES APPLIED WJr'iIIJmIr
TO THE EARTH & ITS EtII/lRONUEtH ~
"000 Lr -02 TRENCH AREA SAMPLING POINTS
MOUNTAIN HOME AIR rORCE BASE
MOUNT AIN HOME IDAHO
ORN IIY CJC DATE: 01 .31 92 P/!UJI;CT NO. FIG. Nfl
CIIK"O IIY .A.K IIF:VISION: 0 89tJ,". 5
. .
-------
)(
----------------
)(
)(
PERIMETER ROAD
x
x
(-- - -- - - - - - - - - -- - -- - --
--...... ---
""
" "('1
" ~
" 'fr "-
1b "-
"0 ........
........
"-
I'" ---
I ~ ----
( '---
I ----
----
I --~
I
I
I
I
I
I
I
I
\
,
,
I
\
,
\
I
,
J
,
,
I
I
,
I
I
I
I
I
I
\
\
I
I
I
I
I
I
.-.J
..,....... .
-' I
",'
. '" .
"
".
",'
-
-
-- .
-- '"
--
/--..........
. .......
/ '
--- "-
1---""""
, ........
I ........... "'"
.......... "-
-....., "'"
"-
"-
"
.
1006
I
~051
I
.
004 ,
" SHAllOW
J,.y DEPRESSION
",'
/' ." .
. ,
./. . /' 008
1-, .
.. ./
t ",'
'-...-'
,.0
~o
001
.
!
, ,
.
/
,,,,,'-'-......
/,.", ".
, / . VOC I 1
/ O~O '001 ;
I
I
/
012
.
011
.
VOC 2
. .
I 002 /
!. O~J /S'HAllOW
, /' DEPRESSION
/'. ENLARGED JX
, "f '" .
'........._,"""-
OOJ
.
lEGEt:'D
wee SAMPLING POINT
WITH DESIGNATION No.
,0
,0
./"
SURr ACE' CONTOUR
50
50
100
-.
o
~-~
APPROXIMA TE SCALE IN FEET,
Woodward-Clyde Consultants ~
[NCtN~ERINC It SCIENCES APPUEO -
'0 ntE EARm It ITS [NVlRDlnAE"' ~
lr -02 DRUM DISPOSAL AREA SAMPLING POINTS
MOUNTAIN HOME AIRrORCE BASE
MOUNT AIN HOME IDAHO
DRN BY
cJtJ[' D BY
PROJECT NO.
89MCI 14H
'IG, HO
6
JWB DATE APRil 1992
-------
11')";1'11 Ftt.~":~":'''1 -t'.::~:. .-,r.:.. :
]-//-'f]
"-
i
i
i
. !'
I
I
i
....
'\ ./
..~.. ,.,/
FENCELINE -"''''''', ....../
RESIDENT ..........-..-.......
(FOR GROUNDWATER EXPOSURES)
41
lllit!O
ASH DISPOSAL AREAS
FROM AIR PIfOTOS
..
o
I
250
500
1000
1500
r
Woodward-Clyde Consultants ~
ENGINEERING' SCIENC£S APPLIED ~
TO TlfE EflRTII , ITS ENVIRDllH[NT ~
- u_.--- --.
ASH DISPOSAL AREA
SCALE IN rEET
-------
Sample No.
LF02- TR-OOI-SS-OOI
LF02- TR-002-SS-OO1
LF02- TR-003-SS-OOI
LF02-TR-004-SS-001
LF02-TR-OOS-SS-OOI
LF02-TR-006-SS-001
LF02- TR-007-SS-OO1
LF02-TR-008-SS-001
LF02-TR-009-SS-001
LF02-TR~IO-SS-001
LF02-TR-OOI-DS-006
LF02-TR~I3-DS-OI0..
LF02-TR-003-DS-OI6
LF02-TR-004-DS-006
LF02- TR-OOS-DS-8.5
LF02-TR-006-DS-007
LF02-TR-007-DS-004
LF02-TR-008-DS-009
LF02-TR-009-DS-3.5
TABLE 2
1RBNCH AREA SEMIVOl.ATILB ORGANICS, pg/kg
AND TOTAL PE1ROLEUM HYDROCARBONS, mg/kg
1,4-Dichlorobenzene
\/I1Q:ti
2,4-Dichlorophenol
360
370
u
u
u
u
u
360
370
360
370
370
380
380
380
400
390
410
]SO
11000
11000
400
370
370
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
Naphthalene
360
370
u
u
u
11000
'."'"
....
11000
Acenaphthene
360
370
360
370
370
380
380
380
400
390
410
]SO
u
u
u
u
u
u
u
u
u
u
u
u
u
Dibenzofuran
360
370
u
u
u
u
u
u
u
u
360
370
370
380
u
u
u
u
u
u
. 0
Diethylphthalate
410
150
11000
.. ...
11000
360
370
360
370
370
380
380
380
400
390
.~?o.. u
.'.. ...,..
/Jltj.>::J/:}::
400
370
370
.
o
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
Auon:ne
360
370
u
u
u
360
370
370
380
380
380
400
u
u
u
u
u
360
370
370
380
u
u
u
u
u
u
u
380
380
400
390
410
]SO
u
u
u
11000
370 U
.., .
,":.',-::.;.::.:
:..::.8Q:.?J:::
u
\::::::+1:::::.,:\/
....
360
370
U
U
U
U
390
11000
U
380
380
400
390
410
U
400
370
370
370
11000 U
400
370
370
U
U
U
370
380
380
380
400
390
U
U
U
.371)... U
/.//410}::::
370 U
}t 10) J
1100 U
o
370
U
410 U
]SO U
1100 U
o
370 U
-------
Sample No.
LF02-TR-001-SS-OOI
LF02-TR-002-SS-OO1
LF02- TR-003-SS-001
LF02-TR-004-SS-001
LF02-TR-005-SS-OO1
LF02- TR-006-SS-001
LF02-TR-007-SS-OO1
LF02-TR-008-SS-001
LF02-TR-009-SS-001
LF02-TR-OIO-SS-OOI
LF02- TR-OOI-Ds.006
LF02-TR-Ol3-DS-O10
LF02-TR-003-DS-OI6
LF02- TR-004-Ds.006
LF02-TR-005-DS-8.5
LF02-TR-006-DS-007
LF02-TR-007-DS-004
LF02-TR-008-DS-009
LF02-TR-009-DS-3.5
390 U
410 U 410 U
3SO U ]SO U ]SO U 3SO U
11 000 U 11000 U 1100 U 11000 U 11000 U 11000 U 1100 U
o 0
Phenanthrene
360 U
370 U
360 U
370 U
370 U
380 U
380 U
Anthracene
360 U
370 U
360 U
370 U
370 U
380 U
380 U
380 U
400 U
390 U
TABLE 2
(Continued)
Fluoranthene
42
370
360
hi)
:i'..J,':':'
U
U
: J
U
BU~benzyi
Pyrene P thalate
360 U 360 U
370 U 370 U
360 U 360 U
..' 9tJ J 370 U
370 U 370 U
380 U 380 U
380 U 380 U
380 U 380 U
\3S(j) >$ .... 400 U
390 U 390 U
Benzo(a)
anthracene
360
370 U
360 U
......
::6ij'l
370
380
380
380
...,
.. '
/tfiii1r::
390 U
U
U
U
U
U
)8/[
390
Chrysene
360
370
360
75
370
380
380
380
U
U
.. ,
U
U
U
U
,'",J,,/}':',
U
2283SA/89MC114H/Rl1f.2 03-02-93(6: 12pm)/RPT /11
370
380
U
U
11000 U 11000 U 1100 U 11000 U 11000 U 11000 U 1100 U
0 0
400 U 400 U 400 U 400 U 400 U 400 U 400 U
370 U 370 U 370 U 370 U 370 U 370 U 370 U .
370 U 370 U 370 U 370 U 370 U 370 U 370 U
" ,
380
380 U
< 3iiCj.:""'( ii/
390
U
, .
Sheet 2 of 3
-------
TABLE 2
(Concluded)
. ,
Sample No.
LF02-TR-OOI-SS-OOI
LF02-TR-002-SS-OO1
LF02- TR-003-SS-001
LF02- TR...()()4..SS-O( I
LF02-TR-005-SS-OO1
LF02- TR...()(J6...SS-01
LF02- TR-007-SS-OO1
LF02- TR-008-SS-001
LF02- TR-009-SS-001
LF02-TR-OIO-SS-OOI
LF02- TR-OOI-DS-006
LF02- TR-OIJ-DS-OIO
LF02- TR-OOJ-DS-OI6
LF02- TR-004. DS-006
LF02-TR-005-D~.5
LF02- TR-006-DS-007
LF02-TR-007-DS-004
LF02- TR-008-DS-009
LF02- TR-009-DS-3.5
Benzo(b)
nuoranthene
Benzo(k)
nuoranthene
U
Ii
U
U
U
U
,','c.,',',",','
. d..
>t
U
Dibenz(a,h)
Benw(a)pyrene Indeno(l,2,J..c:d)pyrene anthracene
U
U
360
370
360
sit:
370
380
380
380
U
U
U
(1.)
U
U
U
U
/J/
U
360
370
360
:~7ij<
:400>
390
U
U
360 U
370 U
360 U
\370 U
370 U
380 U
380 U
380 U
'"
}400 U
390 U
Benzo(g.h,i)
perylene
360 U
370 U
360 U
370 U
370 U
380 U
380 U
380 U
. ..... .......,"
. ..'''' ..........
...... ... ......
...". ...............
......"........... .
nt:::}::
390 U
89 U 410 U
98 U 350 U
11000 U 11000 U 11000 U 11000 U 11000 U ~} .)\"
370 u 370 U 370 U 370 U 370 U 370 U
....... ,9i6/ :',:';;10" ......
1300':,. SSO':':. ...... ....., ...,... .::170,::,::
370
380
380
U 370
U 380
U 380
U 380
""J) >390/
U
U
~::
....
380
1St)"
390
U
390
ti8O~,i
>~~i
e:~~if"
i7iQ?
U
U
U
49.1
45.1
U
U
U
45.1
Positive results are shaded.
All others are non-detect.
°TRPII value reported is from sample LF-02-TR-002-DS-13.5
"Field duplicate for sample LF02-TR-002-DS-13.5.
U = Not detected above sample reporting limit.
UJ = Not detected above sample reporting limit. Sample reporting limit is estimlted.
J = Estimated value below sample reporting limit.
22835A/89MCI 1411/RI7T.2 03-02-93(6: 12pm )/RPT /11
-------
TABLE 1
TRENCH AREA VOLATILE ORGANICS, pg/kg
,Sample No.
LF02-TR-001-SS-001
LF02-TR-002-SS-001
LF02- TR-003-SS-001
LF02- TR -OO4-SS-00 I
LF02- TR-005-SS-OO I
LF02-TR-006-SS-001
LF02-TR-007-SS-001
LF02- TR -008-SS-00 I
LF02- TR-009-SS-OOI
LF02- TR -0 IO-SS-oo I
LF02-TR-001-DS-006
LF02- TR-O I3-DS-O 10.
LF02-TR-003-DS-016
LF02- TR -004-DS-006
LF02- TR-005-DS-8.5
LF02-TR-006-DS-007
LF02- TR-007-DS-004
LF02- TR-008-DS-009
LF02- TR-009-DS-3.5
Methylene Chloride,
u
Trichloroethelle Tetrachloroethene
2-Butallone
'." 4 '.,
13
11
11
11
12
11
12
12
'4"
II
II
11
11
11
12
II
12
UJ
U
U
U
U
U
U
U
:1..:
U
U
U
U
U
U
U
U
)
u
u
II
11
11
11
11
12
11
12
12
12
II
11
11
11
12
II
II
Toluene
u
UJ
U
U
U
U
U
U
U
U
.. .
}"))
~/J
(~.'.....r
4....Ji
.,..~."J..'"
':.3>1"
Ethylbenzelle
II U
II UJ
II U
II U
II U
12 U
II U
12 U
12 U
12 U
12 UJ
II U
II U
Positive results are shaded. All others are non-detect.
. Field duplicate for sample LF02-TR-Q02-I?S-,13.5.
U = Not detected above sample reportmg limit. .
m = Not detected above sample reporting limit. Sample reporting limit is estimated.
) = Estimated value below sample reporting limit.
Note: Location and Sample Identification Codes; LF02-Landfill 2, TR-Trench, SS-Surface Soil, DS-Deep Soil
Example: At Landfitl 02, Trench 001,a deep soil sample was collected at a depth of 6 feet (LF02-TR-001-DS-006).
"'" 1./,..,1." '..'
Styrene
II U
II UJ
II U
II U
II U
12 U
II U
12 U
12 U
12 U
23
II
II
u
UJ
UJ
12
II
II
II
II
U
U
U
UJ
U
12
11
11
UJ
U
U
II
11
U
U
18JSAl89MC114111RI7T.1 04-27-9J(J:02pm)/RPTIII
, -. ~
U
UJ
U
UJ
UJ
U
U
II U
. ..... ....",
..... ......",
...... ......
.':...2'0"0".1,'.0.
12 U
II U
II U
II UJ
II U
1.')<
12 UJ
II U
II U
Xylelles (Total)
II U
t )
II U
2 )
II U
12 U
II U
3<)
12 U
12 U
5 )
j)
5 J
5 J
. 5l
8)
>.2< J
II U
II U
Sheet 1 "r 1
-------
Sample No.
LF02-TR-001~1
LF02- TR-002-SS-OO1
LF02-TR-OOJ.-SS-OOI
LF02- TR-004-SS-001
LfU2-TR-005-SS-OO1
LfU2- TR-006-SS-001
LF02- TR-007-SS-OO1
LfU2-TR..()()8..SS-OOI
LF02-TR-009-SS-OOI
LfU2-TR-OI0-SS-001
LF02-TR-OOI-0S-006
LF02- TR-002-0S-13.5
LF02-TR-OOJ.-OS-OI6
LF02- TR-004-0S-006
LfU2-TR-005-0S-8.5
LF02-TR-006-0S-007
LfU2-TR-007-0S-004
LfU2- TR..()()8..0S-009
LfU2-TR-009-0S-3.5
TABLE 3
TRENCH AREA PESTICIDES/PCBs AND HERBICIDES, ltg/kg
lIeptachlorepoxide Oieldrin4,4'-00B 4,4'-000
1.9
.ii
3.6 U i4....
3.7 UJ~J
U
U
U
U
UJ
3.6 U 3.6 U
7.4 U ~jJ)
3.8 U 3.8 U
3.8 U 1~,.}'.:.}"""
3.8 UJ 3.8 UJ
3.8 U 3.8 U
4 U 4 U
3.9 UJ ~;;zJH
3.6 U
3.7 UJ
3.6 U
.:..7.4 U
3.8 U
.3.8 U
3.8 UJ
3.8 U
4 U
,n'
....3.9 UJ
37 U
3.7 U
4,4'-00T
. ... H'"
.. . . '" ..
... . .....-,"'",
I~f,,\
~\:,.:..
i!i~i~
3.8 UJ
3.8 U
:.~~.~..
J~J
37 U
37 U
4 U
3.7 UJ
3.7 U
. ,
- .,
Alpha-chlordane Gamma-chlordane Aroclor-I242 Aroclor-l2S4 Aroclor-1260 2,4-0
1.9 U
.. ... ..." ..-
... ........
... . .
.. .. ....
.8.~}J...
1.9 U
3.8 U
2 U
2 U
2 UJ
2 U
2 U
2 UJ
38 UJ
38 U
19 U
2.1 U
1.9 UJ
1.9 U
1.9
i?,3.,::.
1.9
3.8
2
2
2
2
2
2
U
36U
... 37 UJ
36U
74 U
38U
38 U
38 UJ
38U
40U
39 UJ
38
38
19
2.1
1.9
1.9
~\J{i'"
U
U
U
U
UJ
U
U
UJ
36 U
37 UJ
36 U
74 U
38 U
38 U
38 UJ
38 U
40 U
39 UJ
.......... d...
.. ............
. . . . . . . . . . . . .
.... ............
. ......... ....
..340.. .......J. ....
\ ..:>:})
730 UJ
40 U
37 UJ
37 U
36
:..,.34.,.,:.
36
74
38
38
U
.::1......:
U
U
U
U
44 U
: 44 U
44 U
45 U
UJ
U
47 U
44 U
45 U
47 U
48 U
48 U
1.9
3.8
2
2
2
2
2
2
8.4
38
38
19
9.4
19
2.1
1.9
1.9
U
U
UJ
UJ
UJ
16 UJ
73 UJ
UJ
160 UJ
730 UJ
U
U
730U
370 U
38
38
40
39
..
160 UJ
730 UJ
U
UJ
44 U
45 U
~~:i
45 U
49 U
45 U
45 U
U
U
73 U
37 U 37 U
Positive results are shaded. All others are nondeted.
U '" Not detected above sample reportin& limit.
UJ '" Not detected above sample reporting limit. Sample reporting limit is estimated.
J '" &timated value below sample reporting limit.
U
U
U
UJ
U
3.7 U 3.7 U
22835A189MCII4H1R 11T.3 03-02-93(6:22pm)/RPT1II
U
UJ
U
40U
37 UJ
37 U
U
730 U
370 U
180 U
370 U
40 U
37 UJ
37 U
-------
TABLE 4
TRENCH AREA METALS OF POTENTIAL CONCERN, mg/kg
Sample No. Arsenic Barium Beryllium Cadmium Chromium Lead Mercury Zinc
LF02- TR-OO I-SS-OOI 3.4 J 172 J 0.49 0.88 UJ 12.7 7.6 J O. 11 UJ 37.3 J
LFU2- TR-002-SS-OO1 3.9 J 190 J 0.56 1.4J 16.2 79J lJ 144 J
LFU2- TR-003-SS-OO1 5 J 163 J 0.56 0.87 UJ 12.7 10. J O. 11 UJ 38.4 J
LFU2- TR-004-SS-001 2.9 J 182 0.58 0.91 U 15.2 10 J O.11U 46.3
LFU2- TR-005-SS-OO 1 3 J 165 0.52 0.92 U 11.8 8.2 J 0.12U 38.8
LFU2- TR-006-SS-001 3.1 J 174 J 0.51 0.9 UJ 13.8 8.8 J 0.13J 45.7 J
LFU2- TR-007-SS-001 3.7 J 164 0.51 0.9 U 11 8.2 J O.lIU 37.6
LFU2- TR-008-SS-OO1 3.3J 177 0.67 0.92 U 12.8 8.2 J 0.12 U 41.8
LF02-TR-009-SS-001 5.8 J 169 0.68 0.95 U 12.5 9.6 J 0.12U 41.7
LFU2- TR-OIO-SS-OOI 12.1 J 243J 0.59 0.96 UJ 12.2 11 J 0.12UJ 42.9 J
LFU2- TR-OOI-DS-OO6 24 J 179 J 0.61 0.97 UJ 12.8 24J 0.19J 125 J
LFU2- TR-002-DS-13.5 10.3 J 601 J 0.5 6.6 J 44.1 991 J O.11UJ 7760J
LFU2- TR-003-DS-OI6 4.9 J 203J 0.64 1.2J 15.4 27.4J 3.3J 196 J
LFU2- TR-004-DS-006 4.6 J 198 0.51 0.9 UJ 13.6 28.6J O.llJ 102 J
LF02- TR-005-DS-08.5 6.9 J 139 0.57 0.9 UJ 14.5 21.4 J 0.131 105 J
LFU2- TR-006-DS-007 3.7 J 205J 0.5 1.2J 14.8 22J O.5lJ 103 J
LFU2- TR-007-DS-004 5.9 J 171 0.86 0.98 UJ 13.4 6.7 0.12UJ 40.4 J
LFU2- TR-008-DS-009 5.6 J 285 0.64 0.9 UJ 9.5 53 0.111 32.7 J ,
LFU2- TR-009-DS-03.5 30.6J 115 0.45 U 0.9 UJ 8.5 5.8 O.11UJ 28.8 J
U = Not detected above sample reporting limit.
UJ = Not detected above sample reporting limit. Sample reporting limit is estimated.
J = Estimated value below sample reporting limit.
2283SA189MCI14HIR IIT.4 03-02-93(6:26pm)/RPT/11 Sheet 1 of 1
-------
Sample No.
LF02-D~l..ss.o~
LF02-D~l
LF02-DI).()()3.SS.OO1
LF02-Do.oos..ss.o~
LF02-D~~
LF02-DD-007..ss.o~
TABLE 5
DRUM DISPOSAL AREA VOLATILE ORGANICS, 11g/kg
Methylene C1Ioride
Trichlorocthcne
Tetrac:hlorocthcne
Toluene
XylenC5 (Total)
Positive n:sull5 8IC shaded. All othCJS are nonctcct.
U . Not detected above sample reporting limit.
UJ . Not detected above sample reporting limit. Sample rcponiDg limit is C5timatcd.
J . Estimated value below sample reporting limit.
22835A/89MCl14H/R17r ~ ~2-93(6:27pm)/RPT /11
-------
TABLE 6
DRUM DISPOSAL AREA SEMIVOIA'I1LES, pgfkg
AND TOTAL PE1ROLEUM HYDROCARBONS, mgfkg
Sample No.
Phenathrene
Di-n-butyl
Anthracene phthalate
Fluor
anthene Pyrene
Benzo( a)
anthracene
Chrysene
390U
LF02-DD-001-SS-O.5 390 U
LF02-DD-002-SS-0.5 350 U
390U
350U
. . . . . . .. . . . . . . . . .
. .. ..................
~[~\tttr~~r~i~~;
3SOU
,"".... ....
",.'" ,'.....
.... ",.........
:~~\::::::390 U
3SOU
3SOU
390 U
3SOU
3SOU
LF02-DD-OOJ.SS.OOl
LF02-D~.s
UJ
....................
.... .....................
..... .... ..... ..............
. . . . . . . . . . . . . .. ...... . . . . . .. ................
...."", ........,......... ...... ........................
.......," ......."",....... ... ............... ..................,......
~~~.l.:.:..:.::.::.::.::.::..:~.:::.:.~.:::~): .........:?::@~~:::::::'::m:::
. .. .. ... . . . . . . . . . . . . . . . . . .. """"""'"
i4Qj:':,:d4rii15O;J. :~4ti){r::::r
Sample No.
Bis(2-002-SS001
47.7U
LF02-DD-OOJ..SS.OOl
LF02-DD-OOS-SS-OO.s
46.7U
Positive results are shaded. All others are non-detect.
U = Not detected above sample reponing limit.
UJ .. Not detected above sample reporting limit. Sample reporting limit is estimated.
J = Estimated value below sample reporting limit.
2283SA/89MC114H/Rl7I'.6 03-02-93(6:27pm )/RPT /11
-------
TABLE 7
DRUM DISPOSAL AREA PFSI1C1DES AND PCBs, J.IfJkg
Sample No.
4,4'-DDE
4,4'-DDT
ArocIor-1254
LF02-DD-001-SS-O.5
LF02-DD-002-SS-001
LF02-DD-003-SS-001
LF02-DD-OOS-SS-O.5
Positive results are shaded. All others are non-detect.
U - Not detected above sample reporting limit.
UJ - Not detected above sample reporting limit. Sample reporting limit is estimated.
J - Estimated value below sample reporting limit.
'"
2283SA/89MC114H/Rl7f.7 03-02-93(6:28pm )/RPT /11
-------
TABlE 8
DRUM DISPOSAL AREA METALS, mg/kg
Sample No.
LF02-DD..ool-SS-OO.5
Arsenic: Barium Beryllium Chromium
Lead
Mercury
Zinc:
Copper Manganese
LF02-DD-002-SS-001
LF02-DD-003-SS-001
..", ",".. .. . ....... ... '"
....,........'"'' ..... .- ...... ....... ........ ..... . . .... ". . .. ...... ........
'" . ...-,- ,"'" ...... ..... ............... ...... .. ... H.....'"'''' ......"on .... .....
... .... ...,................ ...........".... ........ ................ ......... ....... .. ".,...........
....:.:.::.':.'~...'.'..'..'.'.".7.'..'...'..:...1..'..:.:..:..:..:.:.':.':.".:.:...':.'...:.:.244.'..'.."...'..'..'.'.'.....'.':..:.:...':.':.':.:. :.:.':.,.:.:.:.:...:.:..'.'i)...'.'.~.:'.9Z.'..'......'::.:...:.'.:.:.:.:.::..::.'.:.'.:.::..:...:.:.:.:...:.:..::.:.:.:.:.:;i\i...:.:.....:.:.:... :.'::.':,,:.'::.U7.'."1..'.:..i..'.i.. 0.12 U ..:..::.::.::....:.:.:.:.:.968... .'.:.:.:.:.':.: H 9SA J .. ::.::.::46......".l.'''..:.J.''..:.:.:. :...:.':.:::
AN......... .....:;::11::\..
1".I~j'i~~.~i,.,
LF02-DD-OOS-SS-OOS
Positive results are shaded. All others are non-detect.
U - Not detected above sample reporting limit.
UJ = Not detected above sample reporting limit. Sample reporting limit is estimated.
J = Estimated value below sample reporting limit.
2283SA/89MCl14H/R17r.8 03-02-93(6:28pm)/RYI' /11
-------
< ,
TABLE 9
TRENCH AREA
OCCURRENCE OF VOCs IN SOILS
Detected Concentration Frequency of Detection.
Min Max Trench Trench Trench Trench Sample ID
Analyte ltg/kg ltg/kg 1 2 4 5 Max Concentration
Methylene Chloride 4 49 1/6 1/6 0/6 1/1 LF02- TR-OOI-DS-006
2-Butanone 2 4 1/6 0/6 1/6 1/1 LF02- TR-007-DS-004
Trichlorethene 2 5 5/6 4/6 1/6 1/1 LF02-TR-OOI-DS-006
LF02- TR-006-DS-007
Tetrachloroethane' 2 2/6 0/6 0/6 0/1 LF02- TR-001-DS-006
LF02-TR-01.3-DS-010..
Toluene 1 14 6/6 6/6 4/6 1/1 LF02- TR-005-DS-8.5
LF02- TR-006-DS-007
Ethylbenzene 1 2 1/6 3/6 1/6 1/1 LF02- TR-OOI-DS-006
LF02-TR-003-DS-016
LF02- TR-004-DS-006
LF02- TR-005-DS-8.5
LF02-TR-006-DS-007
Styrene 1 0/6 1/6 0/6 0/1 LF02- TR-006-DS-007
Total Xylenes 1 8 4/6 4/6 2/6 % LF02- TR-006-DS-007
. Number of positive results/Number of samples .
.. Sample LF02-TR-013-DS-0I0 was collected from test pit 2 at a depth of 13.5 feet. It is the field duplicate for sample LF02-TR-002-DS-13.5.
2283SA/89MCI14H1R 17T.9 03-02-93(6:28pm)/RYfIlI
-------
TABLE 10
TRENCH AREA
OCCURRENCE OF SEMIVOIA11I.ES IN SOILS
Detected Concentration Frequency of Detection.
Min Max Trench Trench Trench Trench Sample ID
Analyte pg/kg pg/kg 1 2 4 5 Max Concentration
1-4 Dichlorobenzene 170 2400 1/6 1/6 0/6 0/1 LF02- TR-013-DS-0l0"
2,4-Dichlorophenol 410 0/6 1/6 0/6 0/1 LF02-TR-004-DS-006
Naphthalene 50 170 1/6 0/6 0/6 0/6 LF02- TR-013-DS-OI0..
Acenaphthene 80 0/6 1/6 0/6 0/1 LF02- TR-005-DS-85
Dibenzofuran 44 0/6 1/6 0/6 0/1 LF02- TR-005-DS-85
Diethylphthalate 86 0/6 1/6 0/6 0/1 LF02- TR-005-DS-8.5
Fluorene 94 0/6 1/6 0/6 0/1 LF02- TR-005-DS-8.5
Phenanthrene 38 2000 0/6 1/6 0/6 0/1 LF02- TR-005-DS-85
Anthracene' 200 0/6 1/6 0/6 0/1 LF02- TR-005-DS-8.5
FIuoranthene 42 2900 2/6 2/6 1/6 0/1 LF02- TR-005-DS-85
Pyrene 66 1400 1/6 2/6 1/6 0/1 LF02- TR-005-DS-8.5
Butylbenzylphthalate 49 0/6 1/6 0/6 0/1 LF02- TR-005-DS-8.5
Benzo( a) anthracene 55 1300 1/6 2/6 1/6 0/1 LF02- TR-005-DS-85
Chrysene 67 1300 1/6 2/6 1/6 0/1 LF02- TR-005-DS-8.5
Benzo(b )fIuoranthene 87 1300 1/6 2/6 1/6 0/1 LF02- TR-005-DS-8.5
Benzo(k)fIuoranthene 46 S80 0/6 2/6 1/6 0/1 LF02- TR-005-DS-8.5
2283SA/89MCI14H/Rl1f.l0 03-02-93(S:S7pm)/RM' /11 Sheet 1 of 2
-------
TABLE 10
(Concluded)
Detected Concentration Frequency of Detection.
Min Max Trench Trench Trench Trench Sample ID
Analyte pg/kg pg/kg 1 2 4 5 Max Concentration
Benzo(g,h,i)peryleoe 73 2200 1/6 2/6 1/6 0/1 LF02- TR-003-DS-016
Benzo( a)pyreoe 42 910 2/6 2/6 1/6 0/1 LF02- TR-OOS-DS-8.5
Iodeoo(1,2,3-cd)pyrene 43 610 2/6 2/6 1/6 0/1 LF02- TR-OOS-DS-8.5
Dibenz( a,h)anthracene 170 0/6 1/6 0/6 0/1 LF02- TR-OOS-DS-8.5
Carbazole 230 230 0/6 1/6 0/6 0/1 LF02- TR-OOS-DS-8.5
. Number of positive results/Number of samples.
.. Sample LF02-TR-013-DS-010 was collected from test pit 2 at a depth of 13.5 feet. It is the field duplicate for sample LF02-TR-002-DS-13.5.
""'I15A/89MCt 14H/Rl7f.l0 03-m-93(S:S7pm)/RPI'/ll
Sheet 2 or -
-------
TABLE 11
TRENCH AREA
OCCURRENCE OF PESTICIDES/PCBs AND HERBICIDES IN SOILS
Oetected Concentration Frequency of Oetection*
Min Max Trench Trench Trench Trench Sample ID
Analyte ltg/kg ltg/kg 1 2 4 5 Max Concentration
Heptachlorepoxide 1.1 1/6 0/6 0/6 0/1 LF02-TR-002-SS-001
4,4-00E 3 370 5/6 4/6 0/6 1/1 LF02-TR-002-0S-13.5
4,4-000 52 190 6/6 2/6 0/6 1/1 LF02- TR-002-0S-13.5
4,4-001' 2 130 5/6 4/6 1/6 1/1 LF02-TR-002-0S-13.5
Alpha chlordane 8.3 54 2/6 1/6 0/6 0/1 LF02- TR -001- OS-006
Gamma chlordane 9.3 66 2/6 2/6 0/6 0/1 LF02-TR-00I-0S-006
Aroclor 1242 220 0/6 1/6 0/6 0/1 LF02-TR-005-0S-8.5
Aroclor 1254 220 620 2/6 2/6 0/6 0/1 LF02-TR-003-0S-016
Aroclor 1260 34 1/6 0/6 0/6 0/1 LF02- TR -002 -SS-OO 1
2,4-0 41 45000 1/6 2/6 0/6 0/1 LF02-TR-004-0S-006
* Number of positive results/Number of samples.
,
M:\89 I 14\11\1 14I1ROD.TI IIcee
Mountain lIome AFB. Idaho - Record of Decision
Sheet 1 of 1
03/24/93
-------
TABLE 12
TRENCH AREA
OCCURRENCE OF METALS OF POTENTIAL CONCERN IN SOILS
Detected Frequency of Detection.
Concenlralion
Exceeds Min Max Trench Trench Trench Trench Sample ID
Analyle Background'? mg/kg mg/kg 1 2 4 5 Max Concentration
Arsenic yes 3 30.6 6/6 6/6 6/6 1/1 LF02- TR-009-DS-035
Barium no 115 601 6/6 6/6 6/6 1/1 LF02-TR-002-DS-135
Beryllium no 0.49 0.86 6/6 6/6 5/6 1/1 LF02- TR-007-DS-004
Cadmium yes 1.2 6.6 3/6 1/6 0/6 0/1 LF02- TR-002-DS-135
Chromium no 8.5 44.1 6/6 6/6 6/6 1/1 LF02- TR-002-DS-135
Lead yes 5.3 991 6/6 6/6 6/6 1/1 LF02- TR-002-DS-135
Mercury yes 0.11 33 3/6 4/6 1/6 0/1 LF02- TR-003-DS-016
Zinc yes 28.8 7760 6/6 6/6 6/6 1/1 LF02- TR-002-DS-135
. Number of posilive resulls/Number of samples.
2283SA/89MCI14WR 17T .12 03-62-9](6: 11pm)/RPJ'/11
Sheet 1 of 1
-------
Trench Areal
Carcinogens
Aroclor-1260
Benzo( a)anthracene
Benzo(a)pyrene
Benzo(b )fluoranthene
Benzo(k)fluoranthene
Chlordane, alpha and gamma
Chrysene
4,4-DDE
4,4-DDT
Heptachlor epoxide
lndeno( l,2,3-cd)pyrene
Methylene chloride
Trichloroethene
Arsenic
Noncarcinogens
2-Butanone
Chlordane, alpha and gamma
4,4-DDT
Fluoranthene
Methylene chloride
Pyrene
Toluene
Xylenes
Arsenic
Cadmium
Lead
Mercury
Zinc
TABLE 13
CHEMICALS OF CONCERN
Or
Drum Disposal Area
Ash Disposal Area
Carcinogens
Carcinogens
Aroc1or-1254
Benzo( a )anthracene
Benzo(a)pyrene
Benzo(b )fluoranthene
Benzo(k )fluoranthene
Bis(2-ethylhexyl)phthalate
Carbazole
Chrysene
4,4-DDE
4,4-DDT
lndeno( 1 ,2,3-cd)pyrene
Methylene chloride
T etrachloroethene
Trichlorethene
Arsenic
Beryllium
Chromium
Arsenic
Beryllium
Chromium
Noncarcinogens
Noncarcinogens
Anthracene
Bis(2-ethy lhexy l)phthalate
4,4-DDT
Di-n-butylphthalate
Fluoranthene
Methylene chloride
Pyrene
T etrachloroethene
Toluene
Xylenes
Arsenic
Beryllium
Cadmium
Chromium
Lead
Mercury
Zinc
Arsenic
Barium
Beryllium
Cadmium
Chromium
Lead
Mercury
Zinc
1.
Contaminants in surface soils were used for risk assessment purposes at the Trench Area; contaminants in
subsurface and surface soils were used for groundwater modeling.
M:\89114\H\114HROD.TI3/cce
Mountain Hom~ AFB. Idaho - Record of DecisIon
03/24/93
-------
"
'0
TABLE 14
TRENCH AREA
SUMMARY OF SURFACE SOn. AND AIR CONCENTRA nONS
FOR ON-SITE EXPOSURE
Chemical
Methylene chloride
2-Butanone
Trichloroethene
Toluene
Xylenes (total)
Fluoranthene
Pyrene
Benzo(a)anthracene
Cluysene
Benzo(b )fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Indeno( 1,2,3 -cd)pyrene
Heptachlor epoxide
4,4'-DDE
4,4'-DDT
Alpha chlordane
Gamma chlordane
Moelor 1260
Barium
Cadmium
Chromium
Lead
Mercwy
Zinc
Surface Soil mglkg
Mean RME (1)
0.004 0.004
0.002 0.002
0.004 0.004
0.004 0.005
0.003 0.003
0.183 0.226
0.194 0.228
0.160 0.160
0.175 0.195
0,183 0.205
0.193 0.238
0.120 0.130
0.069 0.100
0.001 0.001
0.005 0.008
0.012 0.018
0.002 0.003
0.002 0.003
0.023 0.027
180.0 193.0
0.6 0.7
13.0 14.0
16.0 28.0
0.2 0.3
52.0 69.0
Modeled On-Site Air (2) mglmJ
Mean RME (1)
8.3E-02 8.3E-02
7.SE-03 7.SE-03
1. 7E-02 1. 7E-02
6.SE-03 8.9E-03
1.8E-03 1.8E-03
8.9E-08 l.lE-07
4.7E-08 5.5E-08
1.4E-ll
1.4E-ll
l.5E-ll
1. 7E-ll
9.3E-12
7.1E-12
7.1E-14
S.8E-13
1.3E-12
2.2E-13
2.4E-13
1.9E-12
1.4E-08
S.IE-ll
1.0E-09
(3)
2.3E-ll
5.0E-09
(1) Reasonable Maximum Exposure concentration (either the ma.'
-------
TABLE 15
DRUM DISPOSAL AREA
SUMMARY OF SOIL AND AIR CONCENTRATIONS
FOR ON-SITE EXPOSURE
'1
Surface Soil mg/Kg Modeled On-Site AiP mglm'
Chemical Mean RME(I) Mean RME(I)
Methylene chloride 0.020 0.030 3.1E-Ql 6.1E-Ql
Trichloroethene 0.005 0.006 1.6E-02 2.0E-02
Tetrachloroethene 0.001 0.001 1.3E-Q3 1.3E-Q3
Toluene 0.008 0.017 1.0E-02 2.2E-02
X ylenes(total) 0.004 0.005 1.8E-03 2.3E-03
Anthracene 0.083 0.083 1.2E-06 1.3E-06
Di-n-butyl phthalate 0.044 0.044 7.3E-13
Fluoranthene 0.364 0.867 1.3E-Q7 3.2E-Q7
Pyrene 0.328 0.649 6.0E-Q8 1.2E-Q7
Benzo(a)anthracene 0.338 0.673 l.lE-11
Chrysene 0.340 0.687 1.2E-11
bis(2-Ethylhexyl)phthalate 0.110 0.110 1.8E-12
Benzo(b )fluoranthene 0.386 0.878 1.5E-11
Benzo(k)fluoranthene 0.261 0.490 8.2E-12
Benzo(a)pyrene 0.305 0.595 9.9E-12
Indeno(I,2,3-cd)pyrene 0.100 0.100 1.7E-12
Carbazole 0.100 0.100 1.7E-12
4.4'-DDE 0.147 0.381 6.4E-12
4.4'-DDT 0.349 0.995 1.7E-11
Aroclor 1254 0.114 0.240 4.0E-12
Arsenic 28.0 38.0 6.4E-I0
Barium 297.0 406.0 6.8E-09
Beryllium 1.0 1.7 2.8E-17
Cadmium 1.6 2.7 4.SE-ll
Chromium 28.0 44.0 7.4E-I0
Lead 98.0 133.0 (3)
Mercury 0.3 0.6 9.5E-12
Zinc 693.0 1403.0 2.33E-Q8
(I)
Reasonable Maximum Exposure concentration (either the maximum concentration detected or the 95 percent upper
confidence limit on the arithmetic mean concentration).
Air concentrations were modeled using mean and RME surface soil concentration, emission rates that were calculated
using EPA recommended methods (EPA 1988, 1991), and conservative dispersion modeling.
Air concentrations of lead were not modeled. Exposure to lead in soil is evident in Section VI.D.4.
(7)
(3)
Q:\89114\H\114HROD.TtS/ccc
Mounlain Home AFB, Idaho - Rccord of Dccisioo
03/29/93
Rev. 0
-------
TABLE 16
ASH DISPOSAL AREA
SUMMARY OF SOIL AND AIR CONCENTRATIONS FOR ON-SITE EXPOSURES
Modeled On-Site Air Concentration
Drum Disposal Area Samples (Soil and Ash) (2) Estimated
(Soil and Ash) Background Samples (I) mg/m3 Ash Concentration
(mglkg) (mglkg) Wind Erosion Truck Motorcycle mglkg (5)
Arsenic 38 4.6 3.4E-09 5.7E-06 1.1 E-04 106
Barium 406 163 3.7E-08 6.1 E-05 1.2E-03 904
Beryllium 1.7 0.7 1.6E-1O 2.6E-07 5.IE-06 4
Cadmium 2.7 0.6 2.4E-1O 4.IE-07 8.IE-06 7
Chromium (total) 44 9.8 3.6E-09* 5.9E-06* 1.2E-04* 115
4.0E-IO** 6.6E-07" l.3E-05"
Mercury 0.6 9.8 5.4E-ll 9.0E-08 1.8E-06 1.5
Zinc 1403 43.6 1.3E-07 2.1E-04 4.2E-03 4160
* Chromium +3
.. Chromium +6
(I) Background concentrations are the 95 percent upper confidence limit on the arithmctic mean concentration determined from
background soil samples collected at the Base.
(2) Calculatcd using Drum Disposal Area sample concentration divided by a particulate emission factor (pEF) of I. IE + 10 m3/kg.
The PEF was derivcd following the method of Cowherd (1985). Because the concentrations are very small, they are
expressed in scientific notation, e.g., 8.3E-02. This number is equivalent to 0.0083. The number 1.1 E-07 is equivalent to
0.000000 II.
(3) Drum Disposal Area sample concentration x 0.15 mg/m3 PMIO.
(4) Drum Disposal Area sample concentration x 3 mg/m3 PM 10.
(5) Estimated Ash Concentration = (Drum Disposal Area concentration - 0.66 background concentration)/O.33.
Drum Disposal Area samples contain at least one-third ash.
M:\891 14\11\1 14J1ROD.XI6/daJljdg
MounlAin Home AfB, Idaho. Record of Decision
3/18/93
-------
TABLE 17
TRENCH AREA
MODELED ON-SITE GROUNDWATER CONCENTRATIONS COMPARED
TO RISK-BASED CONCENTRATIONS AND MCLs
Chemical
Methylene Chloride
2-Bulanonc
Trichlorocthcna
T ctnchIorocthc:ac
Toluene
Ethyl Benzene
Stymie
XylCIICI
1.4-DichlOl'Obcnzcnc
2,4-Dichlorophcnol
Naphthalene
2-Methyl Naphthalene
Al:cnaphthcnc
Dibcnzofunn
Diethyl Phthalate
Fluon:nc
Phenanthrene
Anthracc:nc
di-n-Butyl Phthalate
FllIOI'8Dthcnc
Pym\c
Butyl Benzyl Phthalate
Bcnzo(a )anthracene
ChryIcne
Bcnzo(b)Ouonnthcnc
Bcnzo(k)OlIOI'8Dthcnc
Benzo( a)p)'mIC
Indcno( 1.2.3-c,d)pyrcno
Dibcnzo(a,h)anthraccnc
Bcnzo(gh)pcrylene
Carbazole
Heptachlor cpoxide
Dieldrin
DDE
DDD
DDT
Alpha Chlordane
Gamma Chlordane
Aroclor 1242
Aroclor 1254
Aroclor 1260
2,4-D
Ancnic
BarilUll
BcryllilUll
CadmilUll
ChromiIUll
Lead
Mercury
linc
RME Soil
CoaccnInlion
(URlkg)
13.3
4
4.9
2
S.3
2
1
S
lS44
224
170
'3
SO
44
86
94
1507
193
79
1'72
1400
213
1300
1300
1473
257
283
234
170
1082
196
1.1
II
64.6
41.S
32.4
13.7
16.2
134
200
37
6503
1.00E+04
2.S0E+G'
6.IOE+G2
UOE+o3
1.80E+04
1.60E+o5
6.2OE+02
1.20E+o6
Groundwater
Conccntralion (a)
(ug/L)
7.62E-03
2.'9E-03
7.60E-04
1.73E-04
5.93E-04
S.IIE-oS
3.41E-05
2.44E-04
2.09E-o I
6.'4E-03
3.20E-03
1.76E-04
3.83E-02
1.16E-04
2.14E-02
4.94E-04
2.3SE-03
2.55E-04
1.4SE-03
1,25E-03
'.3SE-04
2.96E-02
2.46E-05
1.3SE-04
7.IOE-oS
1.55E-06
S.53E-06
2.ooE-07
2.65E-06
3.6SE-06
1.03E-03
I.39E-06
1.39E-oS
3.43E-06
2.'4E-o,
3.30E-06
USE-06
l.m-06
7.IlE-06
U9E-04
l.96E.06
U4E+oo
2.56E-o I
3.97E-o I
I.94E-04
1.95E-02
1.09E+G0
1.27E-o 1
4.93E-04
5.92E+G0
RBC (b)
(ug/L)
6
600
3
I
3000
2000
2
SOO
3
100
100
NA
2000
40
30000
1000
NA
10000
4000
1000
1000
7000
0.1 (c)
3.2 (c)
0.1 (c)
0.2 (c)
0.014 (c)
0.06 (c)
0.013 (c)
NA
2
0.009
0.00'
0.2
0.3
0.2
0.06
0.06
0.01
0.01
0.01
700
0.0'
3000
0.02
20
40000
NA
10
7000
Federal
MCLa (uw'L)
(metals only)
50
1000
1
S
100
50
o
NA
(a) Modeled groWldwater concentrations are below RBCI and MCLs by facton of 100 to 10.000.000 (coo:cpt 1.4-dichlorobcnzene
which is a factor of 14 below the RBC) for all compounda except anonic. The modeled concentration of ancnic cxcccda the
RBC but doca not exceed the federal MCL. The grGWtdwater concentratiOlll are cxprcucd in scienlific notation; for
example, the nlUllbcr 7.62E-03 iJ equivalent to 0.00762.
(b) Riak-baacd concentrations (RBCI) for clvonic raidential exposures Iiom EPA ReSion X (1991),
b.ucd on 1 E-06 cxceu cancer rille and Haurd Index = I.
(c) RBCI for polycyclic aromatic hydrocarbons arc derived Iiom bcnzo(a)pyrcnc RBC = 0.014 ugiL.
and relative potency facton &om Table 27.
M:189114\H1114HRODJe11
MCII8IIaiD Homo AFD. I
-------
TABLEt8
DRUM DISPOSAL AREA
MODELED ON-SITE GROUNDWATER CONCENTRATIONS
COMPARED TO RISK-BASED CONCENTRATIONS AND MCLs
RME Soil Groundwater
Concentration Concentration (a) RBC (b)
Chemical (uglkg) (ugIL) (ugIL)
METHYLENE CHLORIDE 30 7.95EA)2 6
TRICHLOROETHENE 6 4.41EA)3 3
TETRACHLOROETIIENE 1 4.16EA)4 I
TOLUENE 17 5.86EA)3 3000
XYLENES 5 7.4 I EA)4 2000
ANTHRACENE 83 5.38EA)4 10000
Dl-N-BUiYL PHTHALATE 44 4.02EA)3 4000
FLUORANTHENE 867 3.38EA)3 1000
PYRENE 649 1.22E-03 1000
BENZO(a)ANTHRACENE 673 6.25E-05 0.1 (c)
CHRYSENE 687 3.57E-04 3.2 (c)
BENZO(b)FLUORANTHENE 878 2.01£-04 0.1 (c)
BENZO(k)FLUORANTHENE 490 1.45E-05 0.2 (c)
BENZO(A)PYRENE 595 8.79EA)5 0.014 (c)
INDENO( 1,2,3-C,D)PYRENE 100 4. 19EA)7 0.06 (c)
BIS(2-ETHYLHEXL Y)PHTHALATE 110 2.37E-03 6
DDE 381 9.90EA)5 0.2
DDT 995 4.91£-04 0.2
AROCLOR 1254 240 9.35E-04 0.01
ARSENIC 3.8 I E+04 4.75E+OO 0.05
BARIUM 4.06E+05 3.16E+OO 3000
BERYLLIUM 1.74E+03 2.71E-03 0.02
CADMIUM 2.68E+03 1.70E-Ol 20
CHROMIUM 4.44E+04 1.30E+Ol 40000
LEAD 1.36E+05 5.30E-Ol NA
MERCURY 5.70E+02 2.22E-03 10
ZINC 1.4OE+06 3.38E+Ol 7000
(a) All modeled groundwata- conc:cn1nI1iOB1l except arsenic are below RBCs and MCLs by fadon! of 100 to 10,000,000.
The modeled concentration of arsenic exceeds the RBC but does not exceed the federal MCL. The groundwaIA:r
concentrations are expressed in scientific notation; for example, the number 7.62E-03 is equivalent to 0.00762.
(b) Risk-based concentratiOB1l (RBCs) for chronic residential exposures &om EPA Region X (1991),
based on 1 E-06 cancer risk and HIZItd Index = 1.
(c) RBCs for polycyclic aromatic hydrocarbons are derived &om benzo(a)pyrene RBC = 0.014 ugIL.
and relative potency factors from Table 27.
M:\89114\H\114HROD.XI8
Mountain Home AFB. Idaho - Record of Decision
Federal MCL
(metals only)
(ugll)
SO
1000
1
5
100
IS
2
NA
-------
TABLEt9
ASH DISPOSAL AREA
MODELED ON-SITE GROUNDWATER CONCENTRATIONS
COMPARED TO RISK-BASED CONCENTRATIONS AND MCLs
RME Soil Groundwater
Concentration(a) Concentration(b) RBC(c) MCL(d)
(mglkg) (ugll) (ugll) (ugll)
Arsenic 38 15.3 0.05 50
Barium 406 10.2 3000 1000
Beryllium 1.7 0.009 0.02 1
Cadmium 2.7 0.6 20 5
Chromium 44 42 40,000 100
Lead 136 1.7 NA 15.
Mercury 0.6 0.007 10 2
Zinc 1403 109 7000 NA
(a) Drum Disposal Area Samples (soil and ash). .
(b) Modeled groWldwater concentrations are below RBCs and MCLs by factors of 100 to
10,000,000 for all compoWlds except arsenic. The modeled concentration of arsenic exceeds
the RBC, but does not exceed the federal MCL.
(c) Risk-based concentrations (RBCs) for chronic residential exposure are from EPA Region X (1991),
based on 10[-6] or lE-06 cancer risk and Hazard Index = 1.
(d) Federal Maximwn Contaminant Level for drinking water.
M:\89114\H\114HROD.X19/daVjdg
Mountain Home MH, Idaho. Record of Decision
-------
TABLE 20
INHALATION INTAKE ASSUMPTIONS
Reasonable
Parameter Average Maximum SDEF(l)
Occupational
Inhalation rate (m3 /hr) 1.15 1.3 2.5
Deposition factor (particulates) 0.25 0.25 1
Swallowed fraction (particulates) 0.5 0.5 -(2)
Exposure time (hrs/ day) 2 4 8
Exposure frequency (days/year) 120 250 250
Exposure duration (years) 9 25 25
Body weight (kg) 70 70 70
Residential
Inhalation rate (m3/hr) 0.83 0.83 0.83
Deposition factor (particulates) 0.25 0.25 1
Swallowed fraction (particulates) 0.5 0.5 -(2)
Exposure time (hrs/day) 16 24 24
Exposure frequency (days/year) 270 365 350
Exposure duration (years) 9 30 30
Body weight (kg) 70 70 70
(1) EPA 1991a (SDEF).
(2) SDEF assumes 100% of inhaled particles are deposited in and absorbed in the lung. Therefore,
deposition factor (fraction retained in lungs) is 1.0 and the swallowed fraction of inhaled particulate
does not apply.
2283S-89MC114H/Rl7r.20 03-m-93(6:17pm)/RPT /11
-------
TABLE :n
SOIL INGESTION INTAKE ASSUMPTIONS
Reasonable
Average Maximum SDEF(1)
Occupational
Ingestion rate (mg/day) 10 50 50
Fraction ingested from contaminated 0.25 0.5 1
source
Matrix effect 0.5 1 1
Exposure frequency (days/year) 120 250 250
Exposure duration (years) 9 25 25
Body weight 70 70 70
Residential
Ingestion rate (mg/day) 10 adult 100 adult 100 adult
100 child 200 child 200 child
Fraction ingested from contaminated 0.25 0.5 1
source
Matrix effect 0.5 1 1
Exposure frequency (days/year) 270 365 350
Exposure duration (years) 9 adult 30 adult 30 adult
6 child 6 child 6 child
Body weight (kg) 70 adult 70 adult 70 adult
15 child 15 child 15 child
(1) EPA 1991a (SDEF).
2283.5A189MCl14H1Rl7T.21 ~-93(6: 17pm)/RPT/l1
-------
TABLE n
DERMAL CONTACT WITH SOIL INTAKE ASSUMPTIONS
Reasonable
Average Maximum SDEF(l)
Occupational
Surface area (cm2/day) 1,940 2,910 2,910
Absorbed fraction 0.01 0.1 0.1
Adherence factor (mg/cm2) 05 1.0 1.0
Fraction contacted from contaminated 0.25 05 1.0
source
Exposure frequency (days/year) 120 250 25
Exposure duration (years) 9 25 25
Body weight (kg) 70 70 70
Residential
Surface area (cm2/day) 1,940 2,910 2,910
Absorbed fraction 0.01 0.1 0.1
Adherence factor (mg/cm2) 05 1.0 1.0
Fraction contacted from contaminated 0.25 05 1.0
source
Exposure frequency (days/year) 270 365 350
Exposure duration (years) 9 30 30
Body weight (kg) 70 70 70
(1) EPA does not provide standard default exposure parameters for dermal contact. Values listed are
-------
TABLE 23
"I
GROUNDWATER INGESTION INTAKE ASSUMPTIONS
Residential
Ingestion rate (L/day)
Exposure frequency (days/year)
Exposure duration (years)
Body weight (kg)
SDEF(l)
2
350
30
70
(1)
EPA 1991a (SDEF)
22835A/89MCl14HlRl'Tl".23 03-02-93(6:18pm)/RPT/ll
-------
TABLE 24
SOIL INGES110N INTAKE ASSUMPI10NS
(CHILD 1RESPASSER AT ASH DISPOSAL AREA)
Parameter
Ingestion rate (mg/ day)
Fraction ingested from conta.minated source
Matrix effect
Average
100
1.0
0.5
S2
6
30
Exposure frequency (days/year)
Exposure duration (years)
Body weight
RME
100
1.0
1
104
6
30
2283SA/89MCl14H/Rl7r.24 03-m-93(6:19pm)/RPT /11
-------
TABLE 2S
",
INHALATION INTAKE ASSUMPnONS
(TRUCK DRIVER AND MOTORCYaJST AT ASH DISPOSAL AREA)
Parameter
Inhalation rate (m3/hr)
Exposure time (brs/day)
Exposure frequency (days/year)
Exposure duration (years)
Body weight (kg)
Truck Driver (RME)
1.2
8
250
25
70
~
2283SA/89MC114H/Rl7f.2S OJ.()2-93(6:19pm )/RPT /11
Motorcyclist (RME)
2.5
1
60
6
70
-------
-J TABLE 26
RIDs AND SLOPE FAcroRS FOR CHEMICALS OF CONCERN
Toxicity Carcinogenicity
EPA
Exposure Subchronic Chronic Slope Weight of
Chemical Route RID RID Factor Evidence
(mgfkg-day) (mg/kg-day) (mgfkg-day)"1 Category
Acetone Inha1ation
Oral lE+OO lE-ol
. Aroclor Inhalation
Oral 7.7E+OO B2
Anthracene Inhalation
Oral 3E+OO 3E-Ol
Arsenic Inha1ation 1.5E+Ol A
Oral 3E-03 3E-04 1.7SE+OO A
Barium Inhalation lE-03 lE-04
Oral SE-02 SE-02
Benzo(a)anthracene (1) Inhalation 8.4E-Dl B2
Oral 8.4E-Dl B2
Benzo(a)pyrene (1) Inhalation 5.8E+OO B2
Oral 5.8E+OO B2
Benzo(b)Ouoranthene (1) Inhalation 8.lE-D1 B2
Oral 8.lE-D1 B2
Benzo(k)fluoranthene (1) Inhalation 3.8E-Dl B2
Oral 3.8E-Dl B2
Bis(2-ethylhexyl)phthalate Inhalation B2
Oral 2E-02 2E-02 1.4E-02 B2
2-Butanone Inhalation 9E-ol 9E-02
..
Oral SE-Dl SE-02
-------
TABLE 26
(Continued)
Toxicity Carcinogenicity
EPA
Exposure Subchronic Chronic Slope Weight of
Chemical Route RID RID Factor Evidence
(mg/kg-day) (mg/kg-day) (mg/kg-day)ol Category
Cadmium (food) Inhalation 6.lE +00 Bl
Oral lE-03
Chlordane Inhalation 13E+00 B2
Oral 6E-OS 6E-OS 13E+00 B2
Chromium VI Inhalation S.7E-06 S.7E..{)7 4.lE+Ol A
Oral 2E-02 SE-03
Chyrsene Inhalation 3E-02 B2
Oral 3E-02 B2
4,4'-DDE Inhalation B2
Oral 3.4E-Ol B2
4,4'-DDT Inhalation 3.4E-Ol B2
Oral SE-04 SE-04 3.4E-Ol B2
Di-n-butyl phthalate Inhalation
Oral lE+OO lE-Ol
Fluoranthene Inhalation
Oral 4E-Ol 4E-02
Heptachlor epoxide Inhalation 9.1E+00 B2
Oral 9.1E+00 B2
Indeno(1,2,3-cd)pyrene (1) Inhalation 13SE+00 B2
Oral 13SE+00. B2
Mercury Inhalation 8.6E-OS 8.6E-OS
Oral 3E-04 3E-04
2283S\89MClI4H\RI7r.26 03-02-93(6: 19pm )\RP1\ 11
-------
Chemical
TABLE 26
(Concluded)
Toxicity Carcinogenicity
EPA
Exposure Subchronic Chronic Slope Weight of
Route RID RID Factor Evidence
(mg/kg-day) (mg/kg-day) (mg/kg-day)"1 Category
Inhalation 8.6E.Ql 8.6E'()1 1.65E-03 B2
Oral 6E-02 6E-02 7.5E-03 B2
Inhalation
Oral 3E-Ol 3E-02
Inhalation I.8E-03 B2
Oral lE-Ol lE-Ol 5.lE-02 B2
Inhalation 6E'()1 6E-ol
Oral 2E+OO 2E'()1
Inhalation 6E-03 B2
Oral l.lE-02 B2
Inhalation 9E-02 9E-02
Oral 4E+OO 2E+OO
Inhalation
Oral 2E-Ol 2E-ol
Methylene chloride
Pyrene
Tetrachloroethene
Toluene
Trichloroethene
Xylenes
Zinc
(1) Slope factors derived in Table 27.
-- = No EPA-derived toxicity value.
Sources:
EP A. 1992. Health Effects Assessment Summary Tables (HEAST).
EPA. 1992. Integrated Risk Information System (IRIS). On-line database.
2283S\89MC114H\ R17f.26 OJ.02-93( 6:19pm)\ RP1\ 11
-------
TABLE rT
POTENCY-ADJUS1ED SLOPE FACfORS FOR PAIls
Chcmical
Bcnzo( a)pyrcnc
Bcnzo( a)anthracenc
Bcnzo(b )fIuoranthcnc
BcnzoG)fIuoranthcnc
Bcnzo(k)fIuoranthcnc
Chrysenc
Dibcnzo( a,h)anthracenc
Indcno(1,2,3-cd)pyrcnc
(1)
(2)
EPA 1992 (HEASI').
Potcncy-adjustcd
Slope Factor (3)
Slope Factor (1) Potcncy Factor (2) (mg/kg-day)ol
5.8 1.0 5.8
0.145 0.84
0.140 0.81
0.061 0.35
0.066 0.38
0.0044 0.03
1.11 6.44
0.232 1.35
Cement A&&oc:iatcs, Incorporated. 1988. Comparative Potency Approach for Estimating the Cancer Risk Associated with
Exposure to Mixtures of Polycyl:lic Aromatic Hydroc:arboas. Contract No. 68-024403.
(3)
Cbemic:al-spccific potency fac:tor x bcazo(a)pyrcne slope fac:tor.
22835\89MC1l4H\Rl7f.27 O~2-93\RPT\1l
-------
TABLE 28
SUMMARY OF HEALTII RISKS
ON-SITE OCCUPATIONAL EXPOSURES
Site-Specific Site-Specific
Average Exposure Reasonable Maximum Exposure Standard Default Exposure
Receptor/Pathway Cancer Risk Hazard Index Cancer Risk Hazard Index Cancer Risk Hazard Index
Occupational/french Area
- Ingestion of Trench Particulatcs(l) 7.52&14 2.48&09 9.84FA3 1.17E-08
- Inhalation of Trench Particulates 1.57&12 5.118-06 2.058-11 2.411!-OS 3.168-10 3.70&04
- Inhalation of Trench VOCS 3.29&10 2.27&06 4.398-09 1.091!-OS 1.698-08 4.20B-OS
- Ingestion of Trench Surface Soils 1.028-09 3.l21!-OS 1.33&07 1.57B-03 2.65&07 3.15&03
- Dermal Contact with Trench Surface Soil l.97E.09 1.17&06 7.728-07 ~ 1.54B-«i 4.45&04
Total 3.32&09 3.98B-{)S 9.098-07 1.83&03 1.83B-«i 4.00&03
Occupational/Drum Area
- Ingestion of Drum Particulates(l) 8.57&13 1.358-08 1.128-11 6.348-08
- Inhalation of Drum Particulate 1.228-11 3.708-06 1.608-10 1.731!-OS 2.46&09 2.68&04
- Ingestion of Drum VOCS 8.538-10 4.318-06 2.03&08 3.901!-OS 7.838-08 1.50&04
- Ingestion of Drum Soils 4.40&08 6.31&04 7.12~ 3.67&02 1.42B-OS 7.34&02
- Dermal Contact with Drum Soils 5.36E.oo 8.2SB-«i 3.76E-06 2.90PAIJ 7.51B-«i 5.81PAIJ
Total 5.02&08 6.478-04 1.09B-OS 3.97&02 2.l8B-OS 7.96&02
Occupational/Ash Disposal Area(2)
- Ingestion of Air Particulate(l) 4.62E-12 7.208-08 6.058-11 3.39B-{)7
- Inhalation of Air Particulate 6.62P....ll 1.988-05 8.668-10 9.33B-OS 1.338-08 1.44&03
- Ingestion of Ash 1.53E-07 2.398-03 1.77E"()5 9.96&02 3.53&05 I.99E.{) 1
Total 1.53E.{)7 2.418-03 1.77B-OS 9.97&02 3.53B-OS 2.01&01
(1) Equivalent to swallowed fraction of inhaled particulate malter.
(2) Only metals are of concern. Therefore inhalation of VOCs and dermal uptake are not relevant or significant pathways.
22835A/89MCI14H/RI7f.28 OJ..()2-93(6:21 pm)/RPT /11
-------
TABLE 29
SUMMARY OF HEALTH RISKS
HYPOTHETICAL ON-SITE RESIDENTIAL EXPOSURES
Site-Specirac Site-Specific
Average I!xposure Reasonable Maximum I!xposure
Receptor/Pathway Cancer Risk Hazard Index Cancer Risk Hazard Index
Adult Resident/french Area
- Ingestion of Trench Particulates(l) 9.78&13 3.23&08 6.61&12 6.52&08
- Inhalation of Trench Particulatcs 2.04E-ll 6.64B-OS 1.38&10 1.3SB-04
- Inhalation of Trench VOCS 4.28&09 2.95&05 2.95&08 6.11&05
- Ingestion of Trench Surface Soils 2.29&09 7.02&05 4.658-07 4.598-03
- Dermal Contact with Trench S. Soils 4.44&09 2.62E-06 1.3S&06 3.2SB-04
- Groundwater I!xposurcs NA --M- 5.10&06 ND
Total Adult 1.10&08 1.69B-04 6.95&06 5.128-03
Child Resident/french Area
- Ingestion of Trench S. Soils 7.l2E-a1 2.80&03" 8.67&07 ~.
Total Resident/french Area 8.228-08 2.978-03 7.82&06 4.l7B-02
Adult Resident/Drum Area
- Ingestion of Drum Particulates(l) 1.11&11 1.758-07 7.53&11 3.548-07
- Inhalation of Drum Particulates 1.59&10 4.80&05 1.07&09 9.66&05
- Inhalation of Drum VOCS 1.118-08 5.60&05 1.37&07 2.l8B-04
- Ingestion of Drum Soils 9.89&08 1.42&03 2.50&05 1.07B-0l
- Dermal Contact with Drum Soils 1.21&08 1.86&05 6.58&06 4.248-03
- Groundwater I!xposurcs ~ ~ ~ ND
Total Adult 1.228-07 1.548-03 1.27B-04 1.12&01
Child Resident/Drum Area
- Ingestion of Drum Soils 3.08&06 ~ ~ ~"
Total Resident/Drum Area 3.20&06 1.43B-02 1.73&04 3.27&01
2283SA/89MCI14WRI7l.29 OJ-02-93(6:2Ipm)/RPI'III
....... . , - ,
Standard Default I!xposure
Cancer Risk
Hazard Index
5.28&10 5.l6B-04
2.82&08 S.86B-OS
8.918-07 8.818-03
2.59&06 6.24B-04
5.10E-06 -ML
8.61E-06 1.00B-02
1.66E-06 ~.
1.03&05 8.02B-02
4.11&09 3.73B-04
1.318-07 2.09B-04
4.79&05 2.05&01
1.26&05 8.138-03
9.50&05 -1ill-
1.56B-04 2.14&01
8.93&05 illMl
2.45E-04 6.27&01
Sheet 1 of 2
-------
TABLE 29
(Concluded)
Site-Specific
Average Exposure
Site-Specific
Reasonable Maximum Exposure
Standard Default Exposure
Receptor/Pathway
Resident/Ash Disoosal Area
Cancer Risk Hazard Index Cancer Risk Hazard Index
6.018-11 9.368-07 4.068-10 1.898-06
8.608-10 2.57B-{)4 5.818-09 5.22&04
3.438-07 5.388-03 6.19E-OS 2.918-01
~ ~ 3.10E-04 ~
3.448-07 S.648-03 3.72&04 2.918-01
t.~S 4.978-028 t.16E-04 5.388-018
t.10E-OS S.538-02 4.88E-04 8.298-01
- Ingestion of Particulates(l)
- Inhalation of Particulates
- Ingestion of Ash
- Groundwater Exposure
Total Adult
Child Resident/Ash Disposal Area
- Ingestion of Ash
Total Resident/Ash Disposal Area
Cancer Risk
Hazard Index
2.23E-08 2.008-03
1.19&04 S.588-01
3.10&04 --1:fiL
4.29&04 S.608-01
2.22&04 1.03E+00.
6.51&04 1.59E+00
NA = Not applicable. Exposure to modeled concentrations of chemicals of concern in groundwater are hypothetical and are not included in the average exposure scenarios.
ND = Not done.
Note: Groundwater risks are calculated from results of screening-level leachate and dilution modeling using worst-case conditions.
The chemicals whose concentrations are predicted to approach groundwater ROCs by the model have not been detected in poundwater at the Base.
(1) Equivalent to swallowed fraction of inhaled particulate malter.
8 Subchronic exposure.
2283SA/89MCI14WRI7T.29 03-02-93(6:2Ipm)/RPTI11
-------
TABLE 30
CARCINOGENIC RISKS FROM MODELED CONCENTRATIONS OF ARSENIC IN GROUNDWATER
(RESIDENTIAL EXPOSURES)
Modeled On-Site Concentration
(llgIL)
Cancer Risk
Modeled Off-Site Concentration
IlglL
Cancer Risk
Trench Area
Arsenic
0.25
5 X 10.6
Drum Disposal Area
Arsenic
4.75
9.5 x lO.j
Ash Disposal Area
Arsenic
15.3
3 X 10-4
II /lglL(I)
3 to 0.15 /lgIL (2)
2.6 /lgIL(J)
2 X 10.4(1)
6 x lO.j 3 X 10-6(2)
5 X lO,s(J)
(I)
(2)
Landfill boundary (fence line).
Landfill boundary taking into account that concentration may be overestimated by a factor of 5 to 100.
Dase boundary 2,500 feet southwest of the landfill.
(J)
Note:
The federal Maximum Contaminant Level for arsenic in drinking water is 50 /lgIL.
M:\89114\H\114HROD.T30/ceelmdlcee
Mountain lIome AFB, Idaho - Record of Decision
04/05/93
Rev. 0
. .
-------
TABLE 31
c
SUMMARY OF HEAI.:m RISKS
ASH DISPOSAL AREA: TRESPASSER, mUCK DRIVER, MOTORCYa.JST
A verue
Reasonable Maximum
Receptor
Child Trespasser/Soil Ingestion
Cancer Risk
Hazard Index
2.1E-06
9.6E-03
Cancer Risk Hazard Index
1.6E~5 1.5E-01
3.2E-06 l.5E-Ol(l)
1.1E~5 1.1E+OO(1)
Motorcyclist~tion
Truck Driver /Inhalation
(1)
The magnitude of the hazard index is due solely to inhalation of chromium adhered to particulate
matter. An inhalation toxicity value for chromium is not available in IRIS or HEAST 1992 because
inhalation issues are under review by an EP A workshop. The value used is from HEAST 1991 for
inhalation of chromic acid (Cr VI) fumes, 2E-06 mg/m3, converted to units of mg/kg-day. The
magnitude of the hazard index is due to the assumed toxicity of Cr ill and Cr VI by the inhalation
pathway. The RID used probably overestimates actual toxicity of chromium adhered to particulate
matter.
22835A/89MC114H/R17T.31 03-m-93(6:2Spm)/RPT /11
-------
TABLE 32
MODEL PARAMETER UNCERTAINTY
AND POTENTIAL IMPACfS ON PREDICI'ED CONCENTRATIONS
Model Input
Parameters
Degree of
Uncertainty
low
Leaching layer thickness
Contaminant averaging in
leaching layer
high
Initial Soil water content
moderate
Leaching layer hydraulic conductivity
high
Infiltration rate
moderate
Adsorption moderate
Aquifer thickncssl high
well screen length
Aquifer Hydraulic conductivity high
Aquifer dispersion moderate
Kd value estimation moderate
Direction of groundwater flow moderate
Net impact on model high
predictions
891 14\PP\1 14PPOU2.132 ImdldaJlmd
MOIIDIain HOIDt AFB - OU2. Volume II - LF-02
Appcadixea D-K
Impact
Groundwater concentrations predicted with
INEL model are not impacted by thickness of
leaching layer. HELP model estimated
infUtration rates, however, increase slightly with
increasing thickness for high initial water
contents and decrease slightly with low initial
water contents. Net effects on model prediction
are slight overpredictions or underpredictionl.
May overpredict from 2-10 X for uneven
distribution of contaminants in leaching layer.
Model value assumes soil-ash ratio of 2: 1.
When 1:1 ratio is assured, model predictions
would be underestimated by a factor of 1.3.
Sensitivity analyses indicate that HELP model
generated infUtration rates ean be slightly
sensitive to initial water content for 2o-year
simulation period. Sensitivity analyses showed
mean I value of 0.0058 mlyr with variable
thickness and initial water content compared to
model value of 0.005 mlyr.
Leaching layer K value is mean reference value
of silty ash. When upper range is used, 1 is
approximately 5 times higher than model value.
When low range of K is used. 1 values are 3 to
50 times lower than model value.
Because soil layer K value was used to
determine 1 with HELP model, results may
overpredict from 1 to 2 X. HELP model results
also incorporate 2o-year storm event which
could result in slight « 1 X) overprediction.
May overpredict by up to 10 X due to neglect
of adsorbtive capacity of basalt.
May overpredict by up to 3 X.
Value used typical of mean value for aquifer.
Could result in over or underprediction.
With dispersion, concentrations are reduced by
a factor of from 1 to 2 with transport from
source area border to fenceline.
Model value estimated from laboratory leaching
tests. May overpredict.
May overpredict by a factor of 2 to 3
May overpredict by a factor from 5 to 50 at
point of dilution and 5 to 100 at fenceline
location.
03n6l93
-------
,
TABLE 33
"
IDAHO DEPARTMENT OF HEALm AND WELFARE ASH SAMPLES
JANUARY 1993
ANALYTICAL RESULTS (mgIKg)
Sample No. Arsenic Barium Chromium Zinc
010064(1) 3.52 455 14.1 26.5
010065 4.54 365.s 9.87 25
010066 4.19 273 15 34.1
010067 6.46 311.3 25.8 36
010068 <2 1045.2 11.1 11.2
(I) Idaho Department of Health and Welfare, Bureau of Laboratories tracking number.
Q:\89114\H\114HROD.T33/cee
Mounlain Home AFB, Idaho - Record of Decisioo
03/29/93
-------
Thomas W. Stanley
1540 N. Haskett
Mt Home, ID 83647
v
,
A 1TN: Gary Burton .
Proposed No-Action Plan - OU2
366CSG/CEV
Mountain Home Air Force Base
Mountain Home, Id 83648
2-11-93
It appears from my review of the Proposed no Action Plan and administrative record for this
operable unit and operable unit three that the Air Force, along \vith the EP A and state, has spent
over $900,000 for this proposal, not including funding for their personal to determine the extent of
potential contamination and risk to human health and the environment.
Monitoring wells, sampling of these wells and base production wells and soil samples where
completed. Analysis of the results and a risk assessment has satisfied the EP A arid Air Force that
no action is warranted beyond the 5 year review since expectable exposures or risks to human
health and the environment exist for the land fill.
In addition operable unit 3 will continue to monitor ground water quality at the land fill, cross, up
and down gradient of the land fill at a cost of S 1.5 million. 0 U threes proposed Record of Decision
is due in 1995.
Having a thorough kno,,,.ledge of Air Force land use procedures, conditions at the site, knowledge
of Federal Facilities Agreements and responsibilities of the agencies involved and the DSMOA
process for providing funding to states for DOD NPL bases. And after reading the Idaho Solid
Waste Facilities Act, Chapter 74, sections 39.701 through 39.7421 and Title 1 Chapter 6 of the
Idaho Solid Waste Management Regulations and Standards Manual, I have questions directed at
the State ofIdaho Department of Health and Welfare.
1. Why does it appear that the state does not concur with or except the validity of the data and is in
reality asking for an "action" at this site under Title 1 Chapter 6 of the Idaho Solid Waste
Management Regulations and Standards Manual?
2. Is it wise in today's economic climate to pose an unnecessary additional burden on the tax payer
of $1.1 million to cap the site as the manual requires for "current operating land fills"? Along with
this cost the State would receive funding through the DSMOA. These burdens are assumed by the
tax payer in the end. Does not the evidence support "no action",?
3. What specific additional actions, burden on the tax payer, is the State requiring the Air Force
assume to comply with Title 1 Chapter 6 of the Idaho Solid Waste Management Regulations and
Standards Manual? If it is the capping of the site, then the cost would be approximately $1.1
million dollars, clearly not "no action". If it is additional monitoring wells, then what of the wells
completed for this operable unit and operable unit 3, clearly not "no action". If it is the monitoring
of ground water past the end of 0 U3 and its recommendations or the 5 year review period, then
again a cost is incurred, clearly not "no action". Or is there some other requirement the state is
-------
~ ,J /il~ P
I Q Ga'...iI .:J..J~,.,. '-
7 ' I . 'ZAJf.- -
This site stopped recieving wastes in tee m.:d 197()'::.. My review of39.701 through 39.7421Ie~ds
me to the concIution that the requirerment applies to land fills recieving wastes after Oct. 9 1991
and Oct 1993.
The state needs to be clear in this propos~l as to what they are asking the Air Force to do, so that
we the taxpayer can see the dollars that are being diverted from other NPL sites and environment~l
issues in this state and the country. It Appears to me that the state is trying to back the Air Force
into expending $1.1 million of remedial action construction dollars to continue its funding through
the DSMOA process vs. finding the best solution to the problems and moving on to other more
important issues. Do we not have enough federal and state agencies across the nation that ~re
trying to perpetuate themselves rather then getting the task done they where established for ~nd
. )
movmg on. /
/,;/ t/' I
~K~ ~PM
...~~ ....,,--.:,....- .--:
/<' Thomas W. Stanley
------- |