United States Off ice of
Environmental Protection Emergency and
Agency. Remedial Response
EPA/ROD/R10-92/039
June 1992
Superfund
Record of Decision:
Arrcom (Drexler Enterprise),
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NOTICE
The appendices listed in the index that are not found in this document have been removed.at the request of
the issuing agency. They contain material which supplement. but adds no further applicable information to
the content of the document. AU supplemental material is, however, contained in the administrative record
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50272.101
REPORT DOCUMENTATION 1'. REPORT NO.
PAGE EPA/ROD/R10-92/039
I ~
3. ReclpIent'a ACC888Ion No.
4. Tille and Subtille
SUPERFUND RECORD OF DECISION
Arrcom (Drexler Enterprise), ID
First Remedial Action - Final
7. Aulhor(a)
S. Report 0.18
06/30/92
6.
8. Pet10nnillll Org8lllza1lon RepI. No.
9. Perfonning argalnlzatlon N8me and Acldln8
10. Project/T88klWortl Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponaorillll OI'ganizatlon Name 8nd Addre..
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type 01 Repolt . PerIod Covered
Agency
800/000
14.
15. Supplementary Notes
PB93-964606
16. Abstract (Umlt: 200 word8)
The 1.2-acre Arrcom site is an abandoned waste oil recycling facility located 2.5 miles
southwest of Rathdrum, Idaho. The facility is situated in a rural residential area, and
there are an estimated eight residences within a one-half mile radius of the site. The
site overlies the Spokane Valley-Rathdrwm Prairie Aquifer, a sole source for public and
private drinking water for approximately 350,000 people. From 1960 to 1982, Arrcom used
the site for oil recycling operations, which included an oil/water separation process, a
shaking process to facilitate sedimentation, and a heating process for demulsification.
Waste oil and recycled oil were stored in 27 tanks and 4 tank trucks. Sludge and waste
oils were discarded in three disposal pits on the property or used for dust suppression
on the road. In 1982, the site was abandoned, and investigations by EPA later that year
revealed soil and waste oils contaminated with high levels of solvents, lead, and PCBs.
Emergency response activities were conducted under EPA's removal program between 1983
and 1990. In 1983, 9,700 gallons of waste oils from tanks and 137 cubic yards of
contaminated soil were removed off site. In 1987, 13,225 gallons of waste oils and
sludge and 2,000 cubic yards of soil were removed from tanks and onsite disposal pits.
(See Attached Page)
17. Document An8/y8ia L De8crlptOI8
Record of Decision - ARRCOM (Drexler
First Remedial Action - Final
Contaminated Media: None
Key Contaminants: None
b. IdentifienlOpen-Endec:I Ten118
Enterprise), ID
- ."
" .
c. COSA T1 FieIcIIGroup
18. AvailabiUty SI8tement
19. 5ecu'ity Claaa (This Report)
None
20. Security CI- (This Page)
None
21. No. 01 Pages
44
22. Price
(See ANSl-Z3g.18)
5H InatnJedOtl8 on Re-
272 (4-77)
(Formetly N1IS-35)
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EPA/ROD/R10-92/039
Arrcom (Drexler Enterprise), ID
First Remedial Action - Final
Abstract (Continued)
Also, in 1990, 1,653 tons of contaminated soil were excavated and sent offsite to
hazardous waste incinerators or landfills. Residential ground water wells were sampled
and ground water monitoring wells also were installed. This ROD addresses the final
remedy for the Arrcom site. Previous removal actions have eliminated the need to conduct
remedial action at the site. Therefore, there are no contaminants of concern affecting
this site.
The selected remedial action for this site is no further action, which is based on the
post-removal soil and ground water sampling, supplemental remedial soil and ground water
sampling, and the risk assessment. Removal actions onsite have reduced concentrations of
contaminants in -the soil to levels that do not pose a risk to human health and the
environment. There are no costs associated with this no action remedy.
PERFORMANCE STANDARDS OR GOALS'
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RECORD OF DECISION
DECLARATION, DECISION SUMMARY,
AND RESPONSIVENESS SUMMARY
UNITED STATES
FOR
ARRCOM
RA'rHDRU'M, IDAHO
JUNE 1992
ENVIRONMENTAL PROTECTION
REGION 10
1200 SIXTH AVENUE
SEATTLE, WASHINGTON
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TABLE OF CONTENTS
Declaration of the Record of Decision
Decision Summary
section
Paqe
I.
SITE DESCRIPTION. . . . . . . . . . . .
. . . .
. . .
1
II.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
. . .
. . . .
1
III. COMMUNITY RELATIONS.
. . . . . . . . .
.......
3
IV.
SCOPE AND ROLE OF THE RESPONSE ACTION WITHIN THE SITE
STRATEGY. . . . . . . . . . . . . . . . . . . . . . .
4
V.
SUMMARY OF SITE CHARACTERISTICS.
. . .
. . .
. . . .
5
VI.
SUMMARY OF SITE RISKS.
. . .
. . . . .
. . . .
. . .
9
VII. THE SELECTED REMEDY. .
. . . . . .
. . .
. . . . . . 13
VIII. DOCUMENTATION OF SIGNIFICANT CHANGES. .
. . . .
. . . 13
Appendices
Appendix A:
Appendix B:
Figures and Tables
Responsiveness Summary
Appendix C:
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DECLARATION
ARRCOM
SUPERFUND SITE
SITE NAME AND LOCATION
Arrcom
Rci.thdrum, Idaho
STATEMENT OF PURPOSE
This decision document presents the no further action decision by
the U.S. Environmental Protection Agency (EPA) for the Arrcom
Superfund site in Rathdrum, Idaho. The no further action
decision was developed in accordance with the Comprehensive
Environmental Response Compensation and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and, to the extent
practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP).
This decision is based on the Administrative Record for this
site. The attached index identifies the documents that comprise
the Administrative Record upon which the selection of the no
further action decision is based.
The State of Idaho concurs with the no further action
recommendation.
DESCRIPTION OF THE SELECTED REMEDY
The no further action decision is based on the post-removal soil
and groundwater sampling, the supplemental remedial soil and
groundwater sampling and the Risk Assessment. Based on the
information currently available, previous removal actions at the
site have reduced concentrations of contaminants in soils to
levels that do not pose a risk to human health and the
environment and has eliminated the need to conduct additional
remedial action at the site.
DECLARATION STATEMENT
The no further action decision is protective of human health and
the environment. Because the no further action decision does not
result in hazardous substances, pollutants, or contaminants
remaining at the site above health based levels that allow for
unlimited use and unrestricted exposure, a five year review would
not be necessary.
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signature sheet for the Arrcom Record of Decision by the U.s.
Environmental Protection Agency.
~ ~a./l1/lA
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DECISION SUMMARY
I.
SITE DESCRIPTION
The Arrcom site is an abandoned waste oil recycling facility
located 2.5 miles southwest of the City of Rathdrum, in Kootenai
County, Idaho (See Figure 1). The property consists of
approximately 1.2-acres in the central region of section 10,
Township 51 South, Range 5 West.
The Arrcom site is situated in a rural residential. neighborhood
with an estimated eight residences located within a one-half mile
radius to the north, east, and west. One residential property is
adjacent to the northern edge of the site. The site is bounded
to the southeast by Highway 53, a Northern Pacific Railroad
mainline, and agricultural lands used primarily for growing
forage crops. The marshy drainage basin of Lost Creek is located
0.3 mile to the north/northeast. The site is not fenced.
The site is located over the Spokane Valley-Rathdrum prairie
Aquifer, the sole source for public and private drinking water
for approximately 350,000 people in Idaho and Washington.
Approximately 6,300 of these people live in the primarily rural
residential area within three miles of the ARRCOM site.
II.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
A.
History of site Activities
oil recycling operations began at the facility in the early
1960s. During operation, waste oils were trucked to the site,
underwent processing, and were sold. The oil recycling operation
included an oil/water separation process, a shaking process to
facilitate sedimentation, and a heating process to facilitate
demulsification.
Waste oil and recycled oil were stored in 27 tanks and 4 truck
tanks (Figure 2). Contamination of the environment occurred as a
result of past oil spills from the operation and from leaking oil
storage tanks. sludge and waste oils were discarded in at least
three disposal pits on the property and was spread on the on-site
road.
B.
History of Federal site Investigations and Removal Actions
conducted Under CERCLA
The Arrcom.~ite was abandoned in January 1982, and in August a
site visit of the facility was conducted. During the site visit,
a number of the oil storage tanks were found to be leaking and in
general disrepair. Preliminary sampling of the site in June 1982
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indicated the waste oils and soils at the facility were
contaminated with high levels of solvents, lead and
polychlorinated biphenyls (PCBs) and a potential for groundwater
contamination existed.
A Site Inspection (SI) report was completed in August 1982 and a
Hazard Ranking System score was developed. In December 1982, the
Arrcom site was proposed for inclusion on the National Priorities
List (NPL) and the site received a final NPL listing in September
1983.
with exceptionally high levels of contaminants and large volumes
of waste oils and sludges, emergency response activities were
initiated under EPA's removal program to stabilize the site. A
three phased removal action was performed at the ARRCOM site in
1983, 1987 and in 1990. contaminated soils and sludge disposal
pits were excavated, and waste oils, tanks and buildings were
removed from the site and shipped to off-site hazardous waste
landfill and incinerator facilities. Surface soil and waste oils
were sampled prior to the 1983 and before and after the 1987 and
1990 removal.
As part of the preliminary investigation and removal action
residential groundwater wells in the immediate vicinity of the
site were first sampled in August 1982 and then again in 1987.
In addition, during the 1987 removal, groundwater monitoring
wells were installed at the site. Groundwater samples were taken
in 1987, 1989, 1990.
In 1991, EPA performed a comprehensive assessment of the site
data generated during the removal actions and conducted a limited
sampling effort to fill important data gaps in support of a risk
assessment. This information was used to evaluate the current
nature and extent of contamination at the site and conduct a risk
assessment.
c.
Enforcement Activities
Prior to initiating on-site response activities at the Arrcom
Superfund site, EPA notified the owners and operators of the Site
of its intent to enter the property and conduct response
activities. This Notice of Intent 'was sent in September of 1983.
EPA then initiated and conducted a formal search for potentially
responsible parties (PRP) at the Arrcom Superfund site. This PRP
search was followed up by a number of letters requesting
information from identified PRPs. In July of 1989, a formal
letter was sent to PRPs notifying them of potential liability,
demanding the paYment of response costs and providing an
opportuni~y ,~o conduct further response activities. Some of
these PRPs entered into negotiations with EPA to conduct the work
and/or pay for the response costs. In February of 1991, EPA
filed a complaint against a number of the PRPS seeking to recover
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its response costs. Following the negotiations and the filing of
the complaint, a settlement was negotiated with Atlantic
Richfield Company, Inc; Columbia Lighting, Inc; Kaiser Aluminum
and Chemical Corporation; Warren Bingham; the united states
Bonneville Power Administration and the United states Department
of Interior. The settlement provides for the payment of $1,185,
500.00 to settle the PRP's liability for all costs incurred up to
and including the date of the Record of Decision. The Consent
Decree, which was made available for public comment, was entered
on March 30, 1992.
III. COMMUNITY RELATIONS HISTORY
CERCLA requirements, under Sections 113 (k) «2) (B) (i-v) and 117,
42 U.S.C. ~~ 9613 and 9617 for public participation include
releasing the Risk Assessment report and the proposed plan to the
public and providing a public comment period to allow for public
participation in the decision-making process. EPA met these
requirements by releasing these documents to the public in May
1992. These documents were made available by placing them in an
information repository in the Rathdrum Public Library and EPA
office in Seattle. Notice of a 30 day public comment period on
the documents was placed in the Statesman Review newspaper.
To date the following community relations activities have been
conducted by EPA.
. March 1987
. May 1987
. March 1988
. April 1990
.
August 1991
. April 1992
EPA released a fact sheet announcing the
phase of the removal.
second
EPA released a fact sheet announcing the
completion of the second removal.
Community Relations Plan was completed and
included in the site repository.
EPA released a fact sheet announcing the third
phase of the removal action and briefly described
the first two phases of the removal action.
EPA released a fact sheet announcing need for
additional soil sampling.
EPA released a fact sheet announcing the public
comment period on the Cost Recovery Consent Decree
between the EPA and Potentially Responsible
Parties (PRPs).
. May 20,...1.992 EPA mailed the proposed plan fact sheet, which
explained the results of the risk assessment and
EPA's preferred decision for public comment. .
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. May 22, 1992
A public notice in the Spokesman
the availability of the proposed
assessment, and the dates of the
period.
Review announced
plan and the risk
public comment
. May 22 to June 20, 1992
Public comment period for the proposed plan
and risk assessment.
. June 1992
A responsiveness summary addressing comments
received during the public comment period on
the proposed plan and risk assessment was
prepared and attached to this ROD.
IV.
SCOPE AND ROLE OF THE RESPONSE ACTION WITHIN THE SITE
STRATEGY
EPA has conducted a three phased emergency removal action to
stabilize conditions at the site, which posed a threat to public
health and the environment. The removal action accomplished the
following:
. 1983:
9,700 gallons of waste oils from tanks were removed.
137 cubic yards of contaminated soils removed.
. 1987:
13,255 gallons of waste oils and sludges were removed
from tanks and disposal pits. 2,000 cubic yards of
contaminated soils removed.
. 1990:
1,653 tons of contaminated soil were removed.
contaminated soils and waste oils from the three removals were
shipped to an offsite hazardous waste landfill and incinerator.
In 1991, EPA performed a comprehensive assessment of the site
data generated during the removal action and conducted a limited
sampling effort to fill in important data gaps. This information
was used to evaluate the current nature and extent of
contamination at the site and conduct a risk assessment.
The results of the risk assessment indicate that conditions at
the site do not pose a risk to human health or the environment.
The removal action has eliminated the need to conduct additional
remedial action and the no further action decision is the final
response action for this site.
The no further action decision does not result in hazardous
substances, pollutants, or contaminants remaining at the site
above health based levels and thus allows for unlimited use and
unrestricted exposure. Therefore, a five year review is not
necessary.
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v.
SUMMARY OF SITE CHARACTERISTICS
The following discussion presents a general overview of the site
including a summary of the removal action, sampling and analysis
that was performed as part of the removal action and the sampling
and analysis performed in support of the risk assessment.
A. Geoloqy and soils
The Arrcom facility is located on the northern edge of the
Rathdrum Prairie. The Rathdrum prairie valley trends generally
north to south and is bounded on the east and west by bedrock
highlands that rise over 1,000 feet above the valley floor.
The geologic setting at the ARRCOM site and its surroundings was
greatly influenced by the Pleistocene glacial history of the
area. Multiple glacial advances and recessions smoothed valley
walls, and eroded most of the pre-existing deposits. The eroded
material was then redeposited as till, undifferentiated drift,
and lake sediments. catastrophic floods generated by the
periodic, sudden breaching of glacial Lake Missoula removed much
of the previously deposited clays and silts, thereby forming the
modern landscape. The deposits that remain are coarse textured,
ranging from fine gravels to boulders persisting deep below the
valley floor.
B. Hydrogeoloqy
The Arrcom site is situated over the Spokane Valley Rathdrum
prairie Aquifer. It is an unconfined sole-source aquifer that
provides drinking water for approximately 350,000 people in Idaho
and Washington. An estimated 6,300 people are served by both
public and private drinking water wells located within a 3-mile
radius of the Arrcom facility. The residence closest to the
site, located immediately adjacent to the north side of the
facility, relies on a private well for its drinking water supply,
as do other residences in the immediate area. The aquifer is
also heavily used for crop irrigation.
The Spokane Valley Rathdrum prairie Aquifer exists within the
highly permeable silt, sand, gravel, and boulder Pleistocene
flood deposits. On average, the groundwater table is 135 feet
below ground surface (bgs). The aquifer thickness is typically
greater than 200 feet near the valley center. Irrigation and
drinking water wells in the area are completed at depths greater
than 100 feet bgs but generally less than 200 feet bgs.
Aquifer recharge is primarily from direct precipitation, streams,
lakes, aAd-irrigation. The aquifer gradient in many areas is
very flat. Groundwater generally moves at a fast rate and flows
regionally south-southwest toward the Spokane River (located
about 5 miles from the site).
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There are no surface water bodies on or in the near vicinity of
the Arrcom site.
c.
Nature and Extent of contamination
During the three phases of the removal action conducted between
1983 and 1990 soils were excavated down to depths, ranging from
1 to 20 feet bgs at different locations on the site. soil
samples were collected after two of the removals to verify the
concentration of contaminants remaining in the soils.
contaminated soils and waste oils were shipped to an offsite
hazardous waste landfill and incinerator.
A summary of the removal activities and environmental sampling
that has. been performed is provided below.
. Summary of sampling/Removal Activities:
1983
soil and tank contents at the ARRCOM site were sampled in June
and August 1983. The results of the analyses showed the presence
of a variety of organic contaminants at significant
concentrations in on-site soils and tanks.
In August 1983 EPA authorized an emergency removal action because
the site posed an immediate threat to human health and the
environment. Additional on-site tank and soil sampling was
conducted through September 1983. Benzene was detected in the
soils and the following contaminants (with the highest detected
value in parentheses) were found in the on-site tanks:
chloroform (1 ppm), benzene (100 ppm), toluene (11,000 ppm),
total xylenes (103,OOO ppm), acetone (460 ppm), methylene
chloride (130 ppm), tetrachloroethylene (330 ppm), ethyl benzene
(44,000 ppm), and PCBs (1,250 ppm).
contaminated soils
shown in Figure 3.
site soils and the
Unpumpable sludges
on-site.
were excavated from seven areas which are
The two deep excavations were filled with on-
other excavated areas were leveled.
were left in the remaining tanks and trucks
summary of Sampling/Removal Activities:
1987
Between the 1983 removal action and 1987, illegal oil storage
activities occurred at the Arrcom site. A site assessment
conducted in March and April 1987 showed that two of the tanks
pumped in 1983 (T-21 and T-22) had apparently been refilled.
Additionally, a tar-like material had spilled from a 55-gallon
drum on the north side of the boiler room and large areas of on-
site soi:L.G9ntained visible oil contamination. An estimated
9,000 gallons of oil and other liquids and/or sludge-like
materials were contained in tanks on the site in 1987.
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Composite samples of oil and sludge were taken from 19 tanks and
3 trucks in 1987. Sampling results indicated elevated levels of
organic and inorganic compounds.
In addition, sample analysis of on-site soils indicated the
presence of high levels of organic and inorganic compounds
associated with waste oils and solvents.
In April 1987, EPA authorized the second phase of the removal
action at the Arrcom site with the goal of excavating
contaminated soil and removing all waste oil and on-site
structures. Generally, soils were removed if they were visibly
contaminated or if concentrations measured by a mobile lab
exceedeq excavation screening criteria. The exception was in an
area around underground storage tank T-14. This area was
excavated to a depth of 20 feet, however soil removal ended prior
to the complete removal of visible contaminated soil.
Soil removal activities were completed in July 1987. The areas
excavated during the 1987 soil removal action are shown in
Figure 5.
After the 1987 removal of oil, tanks, and soils, post removal
soil sampling was conducted. Results of this sampling effort are
shown in Tables 1 and 2 and the sample locations are shown in
Figure 4. After the 1987 post-removal sampling was completed,
the excavations were regraded and only the deep excavations were
backfilled with off-site material.
. summary of Sampling/Removal Activities:
1990
The results of the 1987 post-removal samples indicated that there
were a few remaining areas on the site with elevated levels of
PCBs, lead, and PCP. In 1990, EPA undertook a removal action
focused on further excavating these areas. Pre-removal soil
sampling was conducted. Lead concentrations were as high as
13,500 ppm, and PCBs were found at 5.7 ppm. No PCP was detected
above the detection limit of 7 ppm. Other potential organic and
inorganic compounds were thought to be co-located with lead and
PCBs, therefore, PCBs and lead were used as indicator chemicals
to determine the extent of soil excavation. The cleanup levels
for lead and PCBs were 500 ppm and 1 ppm, respectively. The
areas excavated during the 1990 removal are shown in Figure 6.
Because the removal was targeted at reducing the concentrations
of lead, PCBs, and PCP, post-removal soil sampling for these
compounds only was conducted before backfilling the 1990
excavations. The sample locations are shown in Figure 4. The
results Of "this sampling effort are presented in Table 3. The
excavated areas were then filled with off-site fill and gravel.
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. Summary of sampling Activities:
1991
A limited number of additional soil samples were collected in
1991 to support the risk assessment. Surface and subsurface soil
samples were collected in the south area of the site which had
not been investigated during the removal actions. Subsurface
samples were collected below former waste oil pit locations to
assess whether volatile organic compounds which are more mobile
than Lead and PCBs, could have migrated to greater depths below
the bottom of the waste oil excavations and potentially impact
groundwater. In addition, a boring was drilled into the former
T-14 pit location to identify the nature of the contamination
remaining in the soils.
Surface .and subsurface soil samples were analyzed for EPA's
Target compound List (TCL) organics, EPA's Target Analyte List
(TAL) for inorganics, cyanide, and total petroleum hydrocarbons
(TPHs). The sample locations are shown in Figures 7, 8 and 9.
The concentrations of detected TAL organic and TCL inorganic
analytes are shown in Tables 4 and 5, respectively. Table 6
shows the results of the TPH analysis. .
The results suggest that no significant migration of chemicals
has occurred below the formerly-excavated pits. Also, no
additional site contamination was found in the south area of the
site or in the surface soil fill. The samples obtained from
soils below the former tank T-14 confirmed the existence of oily
material and provided estimates of the concentrations of
contaminants present in this material.
. summary of contamination Remaining Onsite
Data from the 1987 post-removal sampling, 1990 post-removal
sampling (PCB, lead and PCP only) and 1991 sampling provide
information on contaminant concentrations remaining onsite after
the 1990 removal. The data suggest that concentrations of
contaminants in soils were significantly reduced and that low
levels of organic and inorganic contaminants remain in the soils
below excavated areas at depths ranging from 1 foot to 25 feet
bgs. The excavation depths and locations are shown in Figure 10.
The samples obtained from soils below the former tank T-14
indicate the existence of oily material and provided estimates of
the concentrations of contaminants present in this material.
These contaminants including tr~chloroethylene (TCE) and xylene
are located 20 feet bgs under clean fill material.
The 1991 investigation suggests organic chemicals in waste oils
had not significantly migrated vertically below the excavation
pits and that contaminants were bound-up in the waste oil matrix
rather than being leached prior to excavation.
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. Groundwater
From 1982 to 1992, five groundwater sampling events occurred at
or in the vicinity of the Arrcom site. The results of these
sampling events are discussed below.
Groundwater samples were first collected from residential wells
in the immediate vicinity of the ARRCOM site in August 1982. In
July 1987, three on-site groundwater monitoring wells were
installed at the Arrcom site. These three monitoring wells and
five local residential wells were sampled in December 1987. The
wells were sampled for volatiles, semi-volatiles, pesticides,
herbicides, PCBs and metals.
The results of the 1983 & 1987 groundwater sampling effort,
indicated that no site related organic or inorganic c?mpounds
were detected in any of the samples.
In March 1989, May 1990, and February 1992 the three on-site
monitoring wells were sampled again for the same parameters, and
no site related organic or inorganic compounds were detected.
VI.
SUMMARY OF SITE RISKS
A risk assessment was prepared to evaluate potential risks to
human health and the environment resulting from contaminants
remaining on-site after the final removal action. The remaining
contaminants in soil that could potentially pose a risk were at
depth and there was not a risk associated with the direct contact
exposure pathway. Therefore, the quantitative risk assessment
evaluated the risk associated with potential exposure to
contaminants in groundwater only. The results of the risk
assessment indicate that conditions at the site will not have an
adverse effect on human health or the environment.
A conservative approach was used to evaluate quantitative health
risks for chemicals of concern in soils as recommended in EPA's
Risk Assessment Guidance for Superfund.. Vol. I: Human Health
Evaluation Manual (EPA 1989a), EPA Region 10 "Draft Supplemental
Risk Assessment Guidance for Superfund" (EPA Region 10 1991), and
other guidance documents. Reasonable conservative estimates and
assumptions were made at every step in the analysis to enhance
confidence in the conclusions of the risk assessment. The Risk
Assessment followed a four step process which is summarized
below.
A.
Human Health Risks
1.
Identification of Chemicals of Concern
The sampling results from soils that remain on-site after the
1987 and 1990 removal action and the additional data collected in
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1991 were used to select chemicals of concern.
As a means of determining which chemicals and portions of the
site pose a potential human health hazard, contaminant
concentrations were compared to risk-based screening levels;
allowable daily intake levels; naturally occurring background
concentrations and the frequency of detection of the contaminants
at the site.
Based on this screening the contaminants of concern that could
pose significant risks are 1,1,2,2-tetrachloroethane a
carcinogen, and xylenes which are noncarcinogens. These
contaminants are located 20 feet bgs underneath clean fill at the
former Tank T-14 location.
2.
Exposure Assessment
Because the site is abandoned the most likely current scenario
for exposure to the chemicals of concern is from a trespasser.
The likely future exposure scenario would be to an on-site
resident. The only contaminant source is assumed to be the
chemicals of concern located in the zone of soil contamination
under former Tank T-14, 20 feet bgs. Direct contact with
subsurface soils at that depth by trespassers or future residents
is highly unlikely. Inhalation of airborne soil particles or
volatile organic compounds from contaminants at that depth is
also highly unlikely.
The only reasonable potential exposure to contaminants is if the
contaminants remaining in the soils migrate downward and come in
contact with the groundwater. Note that the potential for
verticle migration appears to be low based on the 1991 soil
sampling event, which indicated that contaminants have not
significantly migrated vertically. However, to be complete and
conservative this pathway was evaluated further.
Since no groundwater contamination has been detected to date only
a future exposure scenario was evaluat~d. A hypothetical future
on-site residential scenario was chosen rather than a future
worker or nearby resident because it is the most conservative in
terms of the estimated daily intake. A conceptual site model is
presented in Figure 2-11. The exposure pathways evaluated were
ingestion and inhalation of contaminated groundwater.
2.1
Assessment of potential for Future Groundwater
contamination and Associated Human Health Risks
A conservative groundwater infiltration model (MMSOILS Model) was
performetl to calculate the concentration of chemicals that could
potentially reach groundwater with precipitation as the driving
mechanism. The results of the modeling on the chemicals of
concern indicated that only 1,1,2,2-tetrachloroethane could
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potentially reach the groundwater at a concentration of concern.
The concentration of xylene that could potentially reach the
groundwater was below the risk based screening level and
therefore not retained for further risk evaluation.
The concentration of 1,1,2,2-tetrachloroethane that could
potentially reach the groundwater was combined with assumptions
about the behavior of the populations at risk, in order to
estimate the rate at which contaminants could be taken in by the
exposed populations, via ingestion of drinking water or
inhalation of vapors during household water use.
The scenario for future on-site residents was developed using
reasonable maximum groundwater intake assumptions and an
upper bound estimate of the concentration of the contaminant in
groundwater.
Human exposure assumptions are shown in Table 7. Conservative
assumptions associated with estimation of groundwater
concentrations included that the well would draw water only from
the contamination zone and that the concentration would be the
average of the highest concentration potentially seen over a 30
year period.
3.
Toxicity Assessment
Using the conservative assumptions for both the potentially
exposed population and the potential groundwater concentrations,
estimates of the chronic daily intakes (CDI) for 1,1,2,2-
tetrachloroethane were calculated for a hypothetical exposed
individual.
The CDIs for potential future site residents exposed to 1,1,2,2-
tetrachloroethane in groundwater were calculated for the
inhalation and ingestion exposure pathways. These CDIs are shown
in Table 8. The CDI was then combined with toxicological
information, as described below to determine whether the
estimated intake level could pose a threat to human health.
The contaminant of concern at the Arrcom site, 1,1,2,2 -
tetrachloroethane is classified as a Group C carcinogen or
possible human carcinogen. The weight of evidence of
carcinogenicity in animals is limited and inadequate or no data
is available in humans. The cancer slope factor is presented in
Table 9 for the exposure pathways of concern.
Excess lifetime cancer risks were determined for each exposure
pathway by multiplying the exposure level or CDI by the chemical-
specific-cancer slope factor. Chemical-specific cancer potency
(slope) factors have been developed by EPA from human
epidemiological or animal studies. This information was obtained
from EPA's Integrated Risk Information System (IRIS) and the
-------
Health Effects Assessment Summary Tables (HEAST).
4.
Risk Characterization
The cancer risks from ingestion and inhalation of the maximum
potential concentrations of 1,1,2,2-tetrachloroethane predicted
in groundwater at the Arrcom site and the total risk from adding
risks associated with exposure to both drinking water and vapors
are shown in Table 10. The risk estimates are expressed in
scientific notation (i.e. 1 x 10-6 for one in one million;
indicating that an individual is not likely to have greater than
a one in one million chance of developing cancer over his/her
lifetime as a result of site-related exposure). The risk at the
Arrcom site falls within the EPA acceptable cancer risk range of
10-4 to 1"0-6 (NCP, USEPA, 1985e).
Risk estimates calculated from the potency factors reflect a
conservative "upper bound" estimate of the risk posed by
potentially carcinogenic compounds. That is, the true risk is
very unlikely to be greater than the risk predicted and could be
substantially lower. .
Uncertainties in the Risk Assessment for Human Health
The accuracy of the risk characterization depends in a large part
on the accuracy and representativeness of the sampling, exposure
and toxicological data. Most assumptions are intentionally
conservative, so the risk assessment will be more likely to
overestimate risks than to underestimate risk. The procedures
and inputs used to assess potential human health risks in this
evaluation are subject to a number of uncertainties.
The uncertainties are discussed in greater detail in the risk
assessment report.
B.
Ecological Risks
The potential adverse impacts of soil contaminants on local
plants and animals were qualitatively assessed. Potential
ecological receptors could be exposed to soil contaminants
through direct uptake, direct contact, or ingestion.
Potential receptors and exposure scenarios were evaluated and it
was determined that because areas with contaminants remaining
onsite are at significant depth in the subsurface, the Arrcom
site does not pose a risk to ecological receptors or habitats.
c. Human Health and Ecological Risk summary
The results of the risk assessment show that under a current use
scenario and future hypothetical on-site residential scenario,
-------
the site does not pose a risk to human health and the environment.
Under the current use scenario the risk to a trespasser through
soil ingestion and inhalation is highly unlikely. The risk
evaluation for the hypothetical future residential scenario showed
that risks to human health through ingestion or inhalation of
potential contaminants in groundwater were within EPA's acceptable
risk range of 10-4 to 10-6 for carcinogens. Noncarcinogens are not
expected to reach the groundwater in concentrations that result in
adverse noncarcinogenic health effects.
Ecological receptors and habitats are not expected to be adversely
impacted because the source of contamination in surface soils has
been removed from the site.
VII.
THE SELECTED REMEDY
The no further action decision is based on the post-removal soil
and groundwater sampling, the supplemental remedial soil and
groundwater sampling and the Risk Assessment. Based on the
information currently available, the removal actions at the site
have reduced concentrations of contaminants in soils to levels that
do not pose a risk to human health and the environment. Therefore,
EPA has determined that no further remedial action is necessary at
this site. The site now qualifies for inclusion in the "sites
awaiting deletion" subcategory of the construction completion
category of the 'National Priorities List.
VIII.
DOCUMENTATION OF SIGNIFICANT CHANGES
The proposed plan for the Arrcom site was released for public
comment on May 22, 1992. The proposed plan identified the no
further action decision at the Arrcom site. Public comments were
evaluated at the end of the 30-day comment period and are addressed
in the responsiveness summary. It was determined that no
significant chang~s to the proposed plan were necessary.
-------
APPENDIX A
-------
LIST
OF FIGURES
Number
site Location Map. . . . . . . . . . . . . . . . . . .. 1
Arrcom Facility Map. . . . . . . . . . . . . . . . . . . 2
Excavated Areas 1983 .. . . . . . . . . . . . . . . . . 3
1987 & 1990 Removal Sample Locations. . . . . . . . . . 4
Location of Excavated Soil & waste Disposal Areas '87 . . 5
Location of Excavated Soil & Waste Disposal Areas 190 . . 6
Subsurface Soil Sample Location Map. . . . . . . . . . . 7
Surface Soil sample Location Map. . . . . . . . . . . . 8
Results of Organic Analyses of 1991 pit Boring samples 9
Excavated and Waste Disposal Area Map. . . . . . . . . . 10
Arrcom site Conceptual site Model. . . . . . . . . . . . 11
LIST OF TABLES
Summary of 1987 Post-Removal Soil Sampling Results for
Organics. . . . . . . . . . . . . . . . . . . . . . . .
1
Summary of 1987 Post-Removal Soil Sampling Results for
Inorganics . . . . . . . . . . . . . . . . . . . . . .
2
Summary of 1990 Post-Removal Soil Sampling Results
. . .
3
Summary of Organic Chemicals Detected in Soil - 1991
4
Summary of Inorganic Chemicals Detected in Soil - 1991
5
Total Petroleum Hydrocarbons in Soil Samples at the
Arrcom Site. . . . . . . . . . . . . . . . . . .
. . .
6
Assumptions Used to Estimate Exposure of On-site
Residents Via Ingestion and Inhalation of contaminants
in Well Water - Future Use Scenario. . . . . . . . . .
7
Chronic Daily Intake Rates of 1,1.2,2- Tetrachloroethane
Calculated for Exposures to Groundwater Via Ingestion
and Inhalation Pathways. . . . . . . . . . . . . . . .
8
Toxicity Values and Potential Carcinogenic Effects for
Chemicals of Concern at Arrcom . . . . . . . . . . . .
9
Risks of On-site from Ingestion and Inhalation of Well
-------
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1983 EXCAVATION
53
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EXCAVATED AREAS.
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LECEND
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1987 EXCAVATION
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53
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LOCATION OF EXCAVATED SOIL
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1990 EXCA VAT/ON
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1987 EXCAVATION
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AREA NOT EXCA VA TED
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DISPOSAL AREAS
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MAXIMUM DEPTH
OF EXCA VA TION
53
Figure 10
EXCAVATED AND
DISPOSAL AREA
APPROXIMATE SCALE IN FEET
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No: AROREOC3
WASTE
MAP
Technology
-------
Contaminant
Source
-
ARRCOM
SITE
CONCEPTUAL SITE
Contaminant
ReleasefTransport
II_]
FIGURE
MODEL
Exposure
Media
II
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Receptors
Routes of Exposure
-------
-.
TABLE 1
SUMMARY OF 1987 POST -REMOVAL SOIL SAMPUNG RESUL 1S
FOR ORGANIC CHEMICAlS DETECTED AT T1iE ARRCOM SITE (ug/kg)8
FREQUENCY OF RANGE OF DETEC110NS RANGE FOUND
CHEMICAL DETECTION LOW HIGH IN BACKGROUND
. (ug/kg) (ug/kg) SAMPLES
(ug/kg)
VOLA11LES:
Chloromethane 11/108 10J 1,000
Chloroethane 4/108 10J 10J
Methylene chloride 52/108 1J 225J 79-3623J
Acetone 61/108 2 7SOJ 63-1831
Carbon disulfide 18/108 1J SOOJ 1J-4J
2-Butanone 30/108 8J 1,100J 9-4223
1,1,1-Trichloroethane 7/108 1J 18
Vinyl acetate 9/~C8 10J 50J
Bromodichloromethane 5/108 5J 25.1
Trichloroethene 12/108 2J 21
Benzene 16/108 1J 7J
2-Chloroethylvinylether 9/108 11R 15R
2-Hexanone 6/108 10J SOJ
4-Methyl-2-pentanone 6/108 10J 50J
Tetrachloroethene 22/108 1M 64
Toluene 63/108 2 2,500 10-986
Chlorobenzene 17/108 2J 3.800 8-16
Ethylbenzene 4/108 4J 1,600
Xylenes 10/108 2J 23,OOOJ
SEMIVOLA TILES:
Phenol 1/108 2.783
Isophorone 1/108 12,000
Benzoic acid 5/108 420.1 4200J
2-Methylnaphthalene 4/108 87J 5.700
Diethylphthalate 1/108 106J
n-Nitrosodiphenylamine 1/108 120J
Pentachlorophenol 7/108 3,500J 5,1 OOJ
Phenanthrene 1/108 1 ;600J
Di-n-butylphthalate 4/108 100J 1,077
Fluroanthene' 1/108 99J
Pyrene 2/108 83J 93J
Butylbenzyphthalate 1/108 1,9OOJ
3,3-Dichlorobenzidine 9/108 1,46OJ 2,100J
Benzo (a) anthracene 1/108 49.1
-------
TABLE 1 (Continued)
~ SUMMARY OF 1987 POST-REMOVAL SOIL SAMPUNG RESULTS
FOR ORGANIC CHEMICAlS DETECTED AT THE ARRCOM SITE (uglkg)8
FREQUENCY OF RANGE OF DETECTIONS RANGE FOUND
CHEMICAL DETECTION LOW HIGH IN BACKGROUND
(ug/kg) (ug/kg) SAMPLES
(ug/kg)
Chrysene 1/108 90J
Benzo(b)fturoanthene 1/108 63J
Benzo~)flur~hene 1/108 56J
PESTICIDES AND PCBs
Alpha SHC 21108 6J 8J 2J
Beta BHC 3/108 17J 31J
Heptachlor 1/108 2
Aldrin 1/108 120
Endosulfan I 21108 4 23
Dieldrin 1/108 20
Endosulfan sulfate 21108 2 91
AroehlOf' 1016 14/108 96 5,200
Aroehlor 1242 5/108 197 1,700
Aroehlor 1248 6/108 120 8,200J
Arochlor 1260 46/108 16J 7,100J 1J
. Data qualifier "J" indicates the associated value is estimated; "R' indicates the associated value
is rejected; WI" indicates mass spectral critical for positive identification were not met. In. the opinion
-------
TABLE 2
SUMMARY OF 1987 POST-REMOVAL SOIL SAMPUNG RESULTS
FOR INORGANIC CHEMICALS DETECTED AT THE ARRCOM SITE (mglkg}a
RANGE FOUND
FREQUENCY OF RANGE OF DETECT10NS IN BACKGROUND
CHEMICAL DETECTION LOW HIGH SAMPLES
(mglkg) (mg/kg) (mg/kg)
INORGANICS:
Aluminum 108/108 4,990 36,100 15,600-29,000
Antimony 108/108 13J 18J 13-16
Arsenic 104/108 7 48J 16-42
Barium 108/108 34 990 118-320
Beryllium 60/108 0.58 1.7 0.68-1.3
Cadmium 4/108 2.7 4.2 2.8
Calcium 108/108 1,790 33,900 2,6004,170
Chromium 108/108 4.3 60 6.1-14
Cobalt 54/108 4.7 7.8 5.5-7.6
. Copper 108/108 12 100 20-25
Iron 108/108 .9,730 58,200 15,200-22.600
lead 108/108 11 3,880 12-46
Magnesium 108/108 1,950 10,900 1,950.6.990
Manganese 108/108 211 1,010 512J-966J
Mercury 47/108 0.1J 2.4
Nickel 108/108 6.7 28 10-17
Potassium 108/108 816 3,670 1 ,460.2.770
Selenium 58/108 2.6.1 3.7J
Silver 40/108 2.1J 2.9J
Sodium 5/108 582 706 596
Tin 11/108 12 526
Vanadium 108/108 8.1 59 22-36
Zinc 108/108 32 747 61J-181J
-------
TABLE 3
SUMMARY OF 1090 POST-REMOVAL SOIL SAMPUNG RESULTS (mg/kg)
Sa.ple Gri4 Locatio~/
~ ~ !£! pCP Co_en~.
TOOtOnO u 1. 0 VJ .001 V 120
TOOt0622 20 1.0 V .0023 U 18 . .
T0040623 330 4.5 .020 V 'H. .ince PC8 action laval va. axcea4ed.
.a.pla T004061~ va. collactad tollovinq ~
furtber axcavatinq.
TOOtOUt 14 1.0 V .001 U II
TOOt0625 lOt 1.0 V .0012 U 11
TOOt0621 11t 1.0 V .on V 38
T00406J1 41 1.0 V .0081 V 11Q
TOOCOn, '0 1.0 oJ .0012 V 11F .t
T0040630 10 V 1.0 V .001 V 2r
T0040nl 51 1. 0 UJ .001 U 20
TOOCOn2 60 1.0 UJ .001 U Duplicata ot.. .a.pla T0040631.
TOOt06]) 18 1 .0 VJ .001 U 2C
T0040634 20 1.0 UJ .001 U Duplicata of .a.p1e T0040633.
T0040635 240 1.0 U.3 .002 U 38
TOOtOn6 68 1. 0 UJ .001 U Duplic.te ot "e.,,1. T004063S.
TOOton1 241 1.0 V .029 U 7r
TOOtOnl 144 .1 oJ .010 U 11:
'T0040639 62 1.0 U.3 .002 U 10
TQ040640 28 1.0 V .001 U SG
T0040641 81 1.3 .001 U 6r. .inc. PCB aC~lon l.v.l wae ..ceeded.
.a.pl. TOOC06.0 v.. co1l.ctad followiDq
furtber axc.~tiOD.
TOOt06U 113 1.0 U .001 U 6E
TOOC064 3 261 1.0 V.J .011 U u: I
TOOC064t 44 1.0 UoJ .001 U tD
TOOt06U 10 U 1.0 V .001 V 11B
TOOC06U 10 V 1.0 U .001 U Duplic.te of ...pl. TOOC0641.
TOOtOnO 81 1.0 V . .001 U lOB
TootOnl 10 U 1.0 V .001 V 28
TOOt0652 10 U 1.0 0 .001 V 2G
ToOtOn3 10 V 1.0 V .0011 .21;
TOOtOnt 520 1.0 U .001t St. .iDca 1..4 actioD lev.l vaa axceeded. . .
,a.pl. TOOC06.' collacted follovi turtber ~
e.cavatl0n.
TOOt0655 161 1.0 V .012 SF
TOOtOnl 10 U 1.0 0 .001 U ~8
T0040n' 35 1.0 U .001 U 6.
T0040660 123 1.0 V .001 U 58
TOOCO"l 95 14 .001 U 4H. sinc. PC8 action level ve. e1ltc..d.d,
.a.p~a TOOC06S) v.. collected tollovln9
furtber ..cavation.
TOOC0662 69 16 .0011 Duplicat. ot ...ple T0040661
TOOC066) 11 1.0 V .001 V 30
TOOC0664 61 1.0 U .001 V )r
TOOC066S 321 1.0 U .015 3£
TOCC0666 52 LOU .001 V )0
TOOt0661 23 1.0 V .001 V ]C
TOOt0661 n 1.0 V .001 V 58
TOOC0669 44 !-OU .001] C8/CC..qrab ...pl. collected b.tw.en th.
two ,rid locetion..
TOOC0610 10 V 1.0 V .001 V 61..168. qrab ..apl. collected betveen tha
two 9rid location..
TOOC0611 5C !-O 0 .001 0 11..178. qrLb .a.pl. col1ect.d betw.an th.
two 9r1d locatioD..
TOOt0612--' .. 16 1.0 U .001 U 11..111. qrsb .saple collected between tbe
two ,rid locatioD..
TOOCOn] 14 1.0 UoJ .001 U 98
TootOnC 100 1.0 0 .001 U 10<:
ToOtOnS 10 U 1.0 U .001 U 11D
TOOCOn6 10 U 1.0 U .001 V 12F
TOOCOn1 24 1.0 V.J .001 0 128
-------
TABLE 3
SUMMARY OF 1880 POST -REMOVAL SOIL SAMPUNG RESULTS (mg/kg)
(Continued)
Sa.pla ~
"ullber L4ad pce
T00406" 10 V 1.0 V
T0040680 10 V 1.0 UJ
T0040681 1) 1.0 U
T0040U2 10 U 1.0 U
T0040'U RA 1.0 U
T0040684 ]1S 1.0 U
T0040U' '1 1.0 U
T0040U' 10 U 1.0 U .
T0040U 7 10 U 1.0 U
TOOCO'.' 10 U 1.0U
T0040U' 10 Ii to.
T0040690 10 1.0 U
Tooconl 12 1.0 U
T0040697 166 1.0 U
T0040'" no 1.0 U
TOOt0699 15 1.0 U
TOO~C2Cl 235 1.0 U
T0050202 14 1.0 U
TOO'U03 2' 1.0 U
T005U04 36 1.,
T005U05 12 1.0 U
T0050210 S7 1.0 UJ
TOOS0211 10 U 1.0 U
TOOS0212 10 U 1.0 U
T0040'" 10 U 1.0 U.J
T0040657 10 U 1.0 V
PCP
.0029
.001 U
.001 U
.001 U
.001 U
.
.
.
.
.
.
.
.001 U
.001 U
Grid Location/
Co..ent.
8R
'P'
4P'
Duplicate of .a.ple T00406'8
4H, oci9inal .a.ple at thi. 9rid location
.et action 1..el for le.d. but not tor
PCB.
SC
SD
111
Duplicate of ,a.ple T00406.'
4C
SE, or19inal .a.ple .t thla 9r1d locatioD
.et action level for pce, but not tor
lead.
6C
13.1
10D
lOr:
7C
9r
u:
8D
'D. .ince ~e8 action 1e.el v.. e.ceeded.
.a.ple T0050Z1Z collected tollovio9
further elca.atioD.
Duplicate ot ...ple T0040"l.
Ie
9C
9D
Cle.n
Cle.o
fiU
9ravel
. - "0 PCP ,a.ple collected due to EPA/TAT deci.ion that PCP valua. vere at acceptable
li.it. tollovin9 e.c.vation.
U - The .aterial va. ana1Yled tor but va. not det.cted. Tbe ...oci.ted au.ecical v.lue i.
the .a.ple detection li.it or the adju.ted ,a.ple detection li.it.
J - The a..ociated nu.erical value i. an e.ti.ated quantity becau.e the reported
concentration. vere 1... th.n the contract required detection 1i.it. or quality
control criteria vare not .et.
-------
,
TABLE 4
SUMMARY OF ORGANIC CHEMICALS DETECTED IN SOil - 1881.
DeteCtion I~
If.lts (Ol) Frequency of
For londetec:t8 of Detection
location Cf\e8ical (IIQ/kg) Detection (ag/tf)
Background BI8C2-ethylhexyt)Phth8\8te 0.3lo-0.36 31S 0.035-0.1 (8)
Surhce Soil '."-DOE 0.003'-0.0037 2/5 O.OOO5J-O.OOOTSJ
4"I-DOT 0.00J4-0.0037 2/S 0.OOO19J-0.OO34J
Alpha.INC 0.0017-0.0019 11S O.oooa3J
On.Slte Ila(Z-ethylhexyl)Phthal.te 0.33-0.42 31S 0.044-0.11 (a)
Surface .SoU DI-n-lutylphthalate 0.33-0~4Z 11S O.ClSU
PCP O.lH.O 11S 0.039.1
4,"-DOE 0.00~-0.0042 11S O.OOO4J
4,'"-ooT 0.0033-0.0042 2/S O.oo2ZJ-O.OO51J
Aroc lor 1260 0.033.0.01.2 11S 0.075
T renchea IlaC2.ethylhexyt)Phthal8te 0.35-0.42 1/4 0.~2"
1.2-dlchlor~ene 0.35-0-42 1/' . 0.038.1
1.2.(-Tr;chlor~lene 0.35-0.4.2 1/' 0 .06f,J
Methoxychlor 0.001 '0.022 1/' O.~J
Pit Borings BI8(2.ethylhexyt)Phthal8te 0.350-].6 9/12 0.035-0.53 (Ii)
a--.INC (L Indent) 0.0018 1/12 0.00052"
Endoculfen sulfate 0.00~-0.0036 1/12 0.00019"
a....-CMord8ne O.OOUS 1/12 0.00044.1
Aroclor 1254 0.0310-0.036 1/12 0.~1
Aroclor 1260 0.0310-0.036 2/12 0.018-0.021.1
1.1.Z.Z-Tetrachloroethane 0.01 1/12 0.001.1
Toluene 0.01 1/12 0_003.1
Ethylbenzene 0.01 1/12 0.022
Xylene C total) 0.01 2/12 0.004-0.2
-------
TABLE 5'
SUMMARY OF INORGANIC CHEMICALS DETECTED IN SOIL-18i18
Detection
~ U.lta (Ol) fr~ --. of
for IIondetecta of Detection (8)
location C2\e.f al (1IGft8) Oetectlon (88IQ)
8ackgrOlrd Soi I Al UBi,.,. ICA (b) 515 26,100-30,300
Anti8lOOy . 215 3.8-4.8
~
Arsenic ICA 5/5 4.1,6-5.04
88rl\ll IIA 515 267-306
leryll h.. IIA 515 .97'9-1.17
C8ci11 UI ICA 515 0.8-1.2
CalclUl IIA 515 3.500-4.300
Chroal\ll IIA 515 7_14.9.06
Cobalt ICA 5/5 7.44-9.26
Copper ICA SI5 16.3-18.4
Iron IIA 515 16,400-18,600
leed ICA 515 12.4-27.2
"a~iUl ICA 515 3,100-4,010
Manganese ICA 5/5 774-961
Mercury ICA 515 0.03-0.047
Nickel ICA 515 9.05-9.64
PotessiUl ICA 5/5 1,210-1,850
Silver 0.3 4/5 0_}6-0.~
Sodi\ll ICA 5/5 40.6-102
venadi \II ICA 515 21-26.2
Zinc: ICA 515 7'5.8-95.9
Surfece Soi l All.llirua ICA 515 8,740'25,7'00
Area S~les Ant l.any 3 315 3.9
Arsenic ICA 515 2.83-19.3
Sarf 1.11 ICA 515 47.4-257
8erylll UI ICA 515 0.44-0.829
CachIUl ICA 515 0.29'0.99
CalclUl ICA 515 2,650-29,7'00
Chroaf\ll ICA 515 5.48-13
Cobal t ICA 5/5 5.55-10
Copper ICA 515 12.7'25.1
Iron ICA 515 13,300'18,300
leed IIA 515 12.6,192
KagnesiUl ICA 515 1,930-8, no
Manganese I(A 5/5 309-610
Mercury 0_015 315 0.03-0.297
lIickel I(A 5/5 6_5-13.3
PotassiUl I(A 515 1,250-2,280
Sit ver 0.3 215 0.37-0.'1
Sodiua NA 5/5 1 n - 322
Venadiua ICA 5/5 9.16-19.8
Zinc ICA 5/5 45.2-92.2
Trenches Al~irull I(A 4/4 18,000-28,000
Arsenic ICA 4/4 1.66-3.78
Baril.ll I(A 'I' 190-237
8erylliUli I(A '" 0.'9-0.93
C&
-------
TABLE 5 (ContJnued)
SUMMARY OF INORGANIC CHEMICAlS DETECTED IN SOIL - 19918
Detection
l i.lt. (Dl) F req.JenCy lange of ~
For IIondetecti of Detection (8)
location Oteai cal (agJq) Detection (8Glkg)
Nidel 3.e-6.e 'ZI' 2.5-9.21
Potassiua ItA 414 7'92-1.500
Sit ver 0.3 2/4 0.37
Sod".. leA 4/4 168-3Sl.
ThaUiUl 0.25 1/4 0.26
Y8I'\8diUl leA loll, 7.87-21.8
Zinc leA 4/' 18.8-51.7
Pit Borings AluaiN.a ItA 11/12 7.330-14.900
Ant i 8X1Y 3 1/12 20
Arsenic ItA 11/12 '.52-12
Bariua ItA 11/12 ".8-136
Berylliua ItA 11/12 0.37-0.668
C8daiua 0.2 9/12 0_21-0.75
C8lc:iUl leA 11/12 '.060-23.900
Chr08liUli leA. 11/12 7.51-23.1
Cobelt ItA 11/12 S.2'5-9
Copper ItA 11/12 13.5'29.3
Iron ItA 11/12 10.600-18.'00
lead ItA 11/12 9.69-150
MagnesiUli leA 11/12 '.000-11.700
Mangenese leA 11/12 292-523
Mercury 0.015 2i12 0.134
Nicleel 7.12-11_99 8/12 7_98-10.7
Pot8ss h.. ItA 11/12 1.010-5.170
Sit ver 0.15-0.3 2/12 0.38-0.8
Sodh. ItA 11/12 122-1011
Than iUl 0.25 1/12 0.32
YenediUl leA 11/12 8.31-22.2
Zinc ItA 11/12 35.1-96.3
Footnot~: (a) See Appendix A. Table S for (fst of deta qualifiers for Inorganic s~les.
-------
TABLE 6
TOTAL PETROLEUM HYDROCARBONS IN SOIL SAMPLES AT THE ARRCOM SITE - 1991 (mg/kg)
~
~
SAMPLE ID TPH CONCENTRA110N
laboratory Analysis Field Analysis
(mg/kg) (mg/kg)
PB-1-5 <26 >500
. PB44 . 1250 J >500
PB~25 - < 26 >500
PB~5O 2690 J >500
-------
TABLE. ..,
ASSUMPT10NS USED TO ESTIMATE EXPOSURE OF ON.s1TE RESIDENTS VIA
INGEST10N AND INHAlATION OF CONTAMINANTS IN WELL WATER. FUTURE USE SCENARIO
Parameter
Exposure Factora
Intake Rate
Water Ingestion
Vapor Inhalation
2 Uday
15 m3fday
Exposure Freauency
350 days/year
expOsure Duration
- Water Ingestion
Vapor Inhalation
30 years
30 years
Body WeiQht
70 kg
AveraQinQ Time
70 years
Contaminant Concentration
Water Ingestion
. 0.003 gradient. Kd 0.317
0.003 gradient. Kd 0.0412
0.0006 gradient, Kd 0.317
0.0006 gradient, Kd 0.0412
0.029 ug/L
0.033 ug/L
0.14 ug/L
0.15 ug/L
Vapor Inhalation .
0.003 gradient, Kd 0.317
0.003 gradient, Kd 0.0412
0.0006 gradient, Kd 0.317
0.0006 gradient, Kd 0.0412
0.029 ug/l * 0.5 Um3
0.033 ug/L * 0.5 Um3
0.14 ug/L * 0.5 Um3
-------
.
- -.
TABLE. 8
CHRONIC DAILY INTAKE RATES OF 1.1,2.2- TEmACHLOROETHANE CALCUlATED
FOR EXPOSURES to GROUNDWATER VIA THE INGESTION AND INHALATtON PATHWAYS
Parameter
Exposure Point Concentration
COl.
(mglkg/day)
Water Ingestion
0.003 gradient, I\i 0.317
0.003 gradient. I\i 0.0412
0.0006 gracfaent.1\i 0.317
0.0006 gradie~ I\t 0.0412
0.029 ug/L
0.033 ug/L
0.14 ug/L
0.15 ug/L
3.4 X 10-7
3.9 X 10-7
1.6 x 10~
1.8 x 10~
Vapor Inhalation
\ 0.003 gradient. Kd 0.317
0.003 gradient. Kd 0.0412
0.0006 gradient. Kd 0.317
0.0006 gradient. Kd 0.0412
0.029 ug/L . 0.5 Um3
0.033 ug/L . 0.5 Um3
0.14 ug/l . 0.5 Um3
0.15 ug/L * 0.5 Um3
1.3 x 10~
1.5 x 10~
6.2 x 10~
-------
TABLE. '9
TOXICITY VALUES AND POTENTIAL CARCINOGENIC EFFECTS FOR CHEMICALS OF CONCERN AT ARRCOM
, Slope Factor/ Welght-of.Evldence Type of SF Basis/
. Chemical Unit Risk Classification Cancer SF Source
1,1,2,2- Oral:
Tetrachloroethane 2.00E.1 (mg/kg-dayr' C Liver Gavage/IRIS
Inhalation:
S.80E-S (ug/m~.' C Liver Gavage/lRI~
-------
.
1:.-.
TABLE 10
RISKS OF ON-SfTE RESIDENTS FROM INGESTION AND INHALATION OF
WELL WATER - FUTURE USE SCENARIO
Parameter Risk
Water Ingestion 7 x 10-8
0.003 gradient, Kd 0.317
0.003 gradient, Kd 0.0412 8 x 10-8
0.0006 graaaent. ~ 0.317 3 x 10.7
0.0006 gradient, Kd 0.0412 4 x 10.7
Vapor Inhalation 3 x 10.7
0.003 gradient, Kd 0.317
0.003 gradient, Kd 0.0412 3 x 10.7
0.0006 gradient, Kd 0.317 1 x 1 O~
0.0006 gradient, Kd 0.0412 1 x 1 O~
Total Excess Cancer Risk
Qngestion and Inhalation). 3 x 10-7
0.003 gradient, Kd 0.317
0.003 gradient, Kd 0.0412 4 x 10.7
0.0006 gradient, Kd 0.317 2 x 1 o~
0.0006 gradient, Kd 0.0412 2 x 10-6
.
Total excess cancer risks were calculated by adding ingestion
and inhalation risks using two significant figures and then
rounding the total risk to one significant figure. Therefore.
ingestion and inhalation risks in table may nOt add exactly to give
------- |