United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R03-92/158
September 1992
v°/EPA Superfund
Record of Decision:
Suffolk City Landfill, VA
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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 All supplemental material is, however, contained in the administrative record
for this site.
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SOZg-101
REPORT DOCUMENTATION
PAGE
1. REPORTNO.
EPA/ROD/R03-92/158
3. Recrp'nnfe Accession No.
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
Suffolk City Landfill, VA
First Remedial Action - Final
S. Report Date
09/30/92
6.
7. Authors)
8. Performing Organization RepL No.
9. Performing Organization Name and Address
10. Project/Taskwork Unil No.
11. Contract(C)orGrant(G)No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, 'S.W.
Washington, D.C. 20460
13. Type ol Report & Period Covered
800/000
15. Supplementary Notes
PB93-963913
16. Abstract (Limit ZOO words)
The 67-acre Suffolk City Landfill site is an unlined sanitary landfill located in
Suffolk, Virginia. Land use in the area is predominantly agricultural and residential
and the 40 to 45 residences located within 1 mile of the site use the ground water as
their primary source of drinking water. From 1967 to 1985, the City of Suffolk operated
the landfill, which received municipal solid waste from both the City and Nansemond
County. Wastes were disposed of onsite by the trench and fill method, compacted by-
lifts above grade, and then covered with approximately 2 feet of clean soil from an
onsite borrow area. In 1983, when the permit for the operation of the landfill was
reissued, it required the City to close the landfill once the regional landfill became
operational, and to implement a closure plan, which had been submitted to the state.
While preparing to implement the closure plan, the City discovered documentation that
indicated that 1970, 20 tons of pesticide-contaminated debris had been disposed of in
the landfill. A 1970. state memorandum documented that the pesticides were treated with
lime and covered with 2 feet of soil to promote hydrolytic processes that break down the
pesticides. In early 1989, the City placed an impermeable tarpaulin plastic liner over
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Suffolk City Landfill, VA
First Remedial Action - Final
Contaminated Media: None
Key Contaminants: None
b. Identifiers/Open-Ended Terms
c. COSAT1 Field/Group
18. Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. ol Pages
36
22. Price
(See ANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTtS-35)
Department of Commerce
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EPA/ROD/R03-92/158
Suffolk City Landfill, VA
First Remedial Action - Final
Abstract (Continued)
the pesticide disposal area to prevent surface water infiltration through the soil cover.
In mid-1989, the state required the City to implement a temporary leachate collection
system, and the collected leachate was sampled periodically and transported to an offsite
sewage treatment plant. .This ROD addresses the onsite landfill area. Based on findings
during the RI, EPA and the state have determined that the site does not pose an
unacceptable risk to either human health or the environment, and no remedial action is
required. Therefore, there are no contaminants of concern affecting this site.
The selected remedial action for this site is no further action with ground water
monitoring, since sampling results indicate that the site poses no risk to human health
or the environment. There are no costs associated with this no action remedy.
PERFORMANCE STANDARDS OR GOALS: Not applicable.
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RECORD OF DECISION
SUFFOLK CITY LANDFILL
SUFFOLK, VIRGINIA
prepared by
VIRGINIA DEPARTMENT OF WASTE MANAGEMENT
and
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION III
September 1992
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TABLE OF CONTENTS
Page
PART I - DECLARATION 1
I. SITE NAME AND LOCATION 2
II. STATEMENT OF BASIS AND PURPOSE 2
III. ASSESSMENT OF THE SITE 2
IV. DESCRIPTION OF THE SELECTED RESPONSE ACTION 2
V. DECLARATION STATEMENT 2
PART II - DECISION SUMMARY 4
I. SITE NAME AND LOCATION 5
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 5
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 9
IV. SCOPE AND ROLE OF RESPONSE ACTION 10
V. SUMMARY OF SITE CHARACTERISTICS 10
VI. SUMMARY OF SITE RISKS 16
VII. DESCRIPTION OF THE SELECTED RESPONSE ACTION 25
VIII. BASIS FOR THE NO-ACTION ALTERNATIVE 25
IX. DOCUMENTATION OF SIGNIFICANT CHANGES 26
PART III - RESPONSIVENESS SUMMARY 32
I. OVERVIEW 33
II. BACKGROUND OF COMMUNITY INVOLVEMENT 34
III. SUMMARY OF PUBLIC COMMENT AND RESPONSES 36
IV. SUMMARY 41
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LIST OF FIGURES Page
Figure 1 - Site Location 7
Figure 2 - Local Features Surrounding
the Hosier Road Landfill 8
Figure 3 - Sampling Locations and
July 1992 Groundwater Elevations 11
Figure 4 - Hydrogeologic Cross-Sections
of the Hosier Road Landfill 14
LIST OF TABLES
Table l - List of Water Quality Standards for the Hosier
Road Landfill . . 17
Table 2 - Contaminants Detected in Groundwater
Samples at the Hosier Road Landfill 19
Table 3 - Contaminants Detected in Surface Water
Samples at the Hosier Road Landfill 20
Table 4 - Contaminants Detected in Sediment
Samples at the Hosier Road Landfill 21
Table 5 - Estimation of Carcinogenic Risk
Associated with Ingestion of Groundwater
Contaminated with Metals (Dissolved)
at the Hosier Road Landfill 23
Table 6 - Estimation of Chronic Hazards
Associated with Ingestion of Groundwater
Contaminated with Metals (Dissolved)
at the Hosier Road Landfill 24
Table 7 - Estimation of Carcinogenic Risk
Associated with Ingestion of Contaminated
Surface Water near the Hosier Road Landfill .27
Table 8 - Estimation of Chronic Hazards
Associated with Ingestion of Contaminated
Surface Water near the Hosier Road Landfill .28
Table 9 - Estimation of Carcinogenic Risk
Associated with Ingestion of Contaminated
Fish near the Hosier Road Landfill 29
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LIST OF TABLE (Continued)
Page
Table 10 - Estimation of Chronic Hazards
Associated with Ingestion of Contaminated
Fish near the Hosier Road Landfill
30
Table 11 - Estimation of Carcinogenic Risk
Associated with Ingestion of Contaminated
Sediments near the Hosier Road Landfill ....31
Table 12 - Estimation of Chronic Hazards
Associated with Ingestion of Contaminated
Sediments near the Hosier Road Landfill ....32
APPENDICES
Appendix A:
Appendix B:
Appendix C:
Letters Received During Comment Period
Glossary of Superfund Terms
Index of Documents contained in the
Administrative File
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PART I
DECLARATION
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DECLARATION
I. SITE NAME AND LOCATION
Suffolk City Landfill (Hosier Road Landfill)
Suffolk, Virginia
II. STATEMENT OF BASIS AND PURPOSE
This Record of Decision presents the response action selected
for the Suffolk City Landfill, located in Suffolk, Virginia (Site).
The Environmental Protection Agency (EPA), in consultation with the
Commonwealth of Virginia Department of Waste Management (VDWM), has
selected a response action for the Site. The response action was
selected in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980, as amended
(CERCLA), and the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). The decision contained herein is based on
information included in the Administrative Record File for this
Site. An index of documents for the Administrative Record File is
included in Appendix C.
VDWM concurs with the selected response action.
III. ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances at the
Site have not presented, and do not currently present, an imminent
and substantial endangerment to public health, welfare, or the
environment.
IV. DESCRIPTION OF THE SELECTED RESPONSE ACTION
The selected response action consists of no remedial action.
Groundwater monitoring will be performed to provide continued
assurance that no unacceptable risks to human health or the
environment occur.
VTION STATEMENT
EPA, in consultation with VDWM, has determined that no
remedial action is necessary at this Site to ensure protection of
human health and the environment. Therefore, the Site now
qualifies for inclusion in the "site awaiting deletion" subcategory
of the Construction Completion category of the National Priorities
List (NPL). Because hazardous substances remain at the Site,
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however, a review will be conducted within five (5) years after
this Record of Decision (ROD) is signed, to assure continued
protection of human health and the environment.
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
/Edwin B. Erickson
Administrator, Region III
y^&
Date
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I. SITE NAME AND LOCATION
The Suffolk City Landfill Site, also referred to as the Hosier
Road Landfill (Landfill or "Site"), is a 67-acre parcel situated
east of Hosier Road (Virginia Route 604) in the City of Suffolk,
Virginia (Figure 1).
To the north of the Site is a 37-acre borrow area from which
current cover material for the Landfill was obtained. Bordering
the Site to the east is undisturbed upper reaches of Pocosin Swamp,
and an escarpment that defines the western boundary of the Great
Dismal Swamp. To the southeast of the Site lies a privately-owned
road. Properties in the vicinity of the local area of the Site
include the Suffolk airport, a currently-closed wood preserver, two
plant nurseries, and parts of forest and farm lands. Two unnamed
streams (unnamed streams N and E) are located north and east of the
Site. These streams meet in an area adjacent to and northeast of
the Site before emptying into the Pocosin Swamp, located east of
the Sitie (Figure 2) .
The City of Suffolk (City) is primarily an agricultural
community. Based on the 1990 Census, the population of the City
was 52,141. There are about 40 to 45 residences located within one
mile of the Site. Most of these residences are in areas south of
the Site, where groundwater is the primary source of drinking
water.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
The City of Suffolk operated the Landfill from approximately
1967 to January 1985 as a sanitary landfill in accordance with
Permit No. 310 issued by the Virginia Department of Health (VDOH).
The Landfill received municipal solid waste primarily from the City
and, before 1974, Nansemond County. The City leased the Site from
1967 until 1983, when it purchased the Site from Elon College and
Suffolk Bible College.
The Landfill is unlined. Municipal wastes were disposed of
in the Landfill by the trench-and-fill method followed by filling
and compaction by lifts above grade. Compacted waste was then
covered with approximately two feet of clean soil from a borrow
area onsite. This disposal method resulted in surface elevation of
20 to 30 feet above the undisturbed ground level.
The permit for the operation of the Landfill was most recently
reissued in June 1983. The reissued permit required the City to
close the Landfill when the regional landfill became operational,
and implement the closure plan, which had been submitted to VDOH.
In preparation for the implementation of the closure plan, the City
discovered documentation indicating that several tons of debris
that contained pesticides had been disposed of in the Landfill in
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1970. The disposed pesticides, which were damaged by a fire at the
Dixie Guano Company, included Disulfoton, Cu7 Sulfur, 7 Sulfur,
Thimet, and Cyanox. On June 3, 1970, representatives of the Tri-
County Health District, the former Nansemond County (now city of
Suffolk), State Water Control Board, the Virginia Department of
Agriculture, and the Industrial Hygiene Department met to determine
a disposal method for the remaining pesticides (approximately 20
tons). At this meeting, an agreement was reached that disposal of
the remaining pesticides would occur in a lime-lined trench of 30
feet long x 30 feet wide x 3 feet deep, and that the pesticides
would be covered with lime and two feet of soil. The lime would
promote hydrolytic processes that breaks down the pesticides.
According to a June 5, 1970 Virginia Department of Health memo, the
pesticides were treated with lime and covered with two feet of
soil, as recommended in the June 3, 1970 meeting, in two trenches
of approximately 120 feet long x 25 feet wide x 3 feet deep.
Following the City's notification of the pesticide disposal at
the Site, EPA completed a Preliminary Assessment in April 1985 and
a Site Inspection in July 1986. As a result of these efforts and
a Hazard Ranking System (HRS) scoring of the Site, EPA proposed to
include the Site on the NPL in June 1988 and finalized the
inclusion in February 1990.
In early 1989, the City placed an impermeable tarpaulin
plastic liner over the pesticide disposal area to prevent surface
water infiltration through the soil cover. The liner covers an
area of approximately 100 feet long x 36 feet wide. A warning sign
is currently posted next to the pesticide disposal area.
In June 1989, the City and VDWM entered into an Administrative
Order on Consent (AOC) which required the City to conduct a
remedial investigation/feasibility study (RI/FS) to determine the
nature and extent of contamination and to develop and evaluate
cleanup alternatives. The AOC additionally required that the City
implement a temporary leachate collection system (TLCS). The TLCS
has been implemented and is currently being operated by the City
Department of Public Works. The collected leachate has been
periodically sampled and transported to Hampton Roads Sanitation
District (HRSD) sewage treatment plant for treatment in accordance
with a permit issued by (HRSD).
The findings of the Remedial Investigation (RI) are discussed
in Section V (Summary of Site Characteristics) and Section VI
(Summary of Site Risks) and provide the basis for the determination
that no remedial action is required at the Site. Following
issuance of this Record of Decision, the City interns to pursue
final closure of the Landfill in accordance with r,.«rrent State
requirements.
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Figure l - site Location
UFFOLK
DISMAL
SWAMP
HOSIER ROAD
LANDFILL
3OOO' O 3OOO' 400O' 6OOO
APPROX. SCALE IN FEET
* (from 195<» U.S. Geological Survey 15' Suffolk Quadrangle -- contour interval is 10 feet)
scs ENGINEERS
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Figure 2 - Local Features Surrounding the Hosier Road Landfill
i
00
I
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III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The area residents' primary issues of concern expressed in
community interviews conducted by VDWM in 1989 and 1991 included
the potential for contamination of groundwater and surface water
and property values. The potential for pollution of area
groundwater caused by leachate or pesticides escaping from the
Landfill into wells or nearby waters was raised. Residents within
a three mile radius of the Site rely primarily on wells for their
drinking water, and thus were concerned about how the Landfill
might be affecting the groundwater. The possibility of surface
water runoff affecting the wildlife and flora of the Pocosin and
Great Dismal Swamp was also of concern.
The Community Relations Plan was written in October 1989 and
updated by VDWM in 1991. Throughout the RI/FS, updates on Site
activities were provided on a quarterly basis and VDWM responded to
questions from residents and officials. Two community workshops
were held prior to the onset of the RI/FS, one on January 29, 1991,
and one on March 17, 1991. The first workshop, held at City Hall,
was sparsely attended by two members of the local press and three
local residents. The primary concern at this workshop was the
fiscal outlay expected for the investigation and cleanup. The
March 17, 1991 workshop was scheduled at the request of several
interested Hosier Road area residents who were unable to attend the
January workshop. Approximately 40 residents attended the March
meeting. Residents expressed interest in learning more about
Technical Assistance Grants (TAGS), and met again with a VDWM
representative on May 16, 1991 to obtain a TAG application binder
and ask additional questions. Approximately 30 residents attended
the May TAG meeting. An additional workshop was held by VDWM on
April 9, 1992 to discuss the investigation findings, and update
citizens on the status of the Remedial Investigation.
In accordance with CERCLA §§ 113(k), 117(a), and 121(f), the
Proposed Plan was made available to the Site community. Public
notices were placed in the August 22, 1992 edition of the Suffolk
News Herald and the August 23, 1992 edition of the Virginian-Pilot
and Ledger Star. Furthermore, a notice of the availability of the
Proposed Plan and of the public comment period and the public
meeting was announced on the municipal cable channel.
Additionally, citizen advisories were sent to members of the
mailing list. The public comment period began on August 23, 1992
and continued through September 22, 1992.
At the September 3, 1992 Proposed Plan public meeting, which
was held at Mt. Ararat Church, representatives from VDWM presented
an overview of the Superfund process, summarized the sampling
results and Proposed Plan, and answered questions from community
members. EPA officials were also present to address questions and
concerns raised. A formal response to questions and comments
received during the comment period can be found in the
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Responsiveness Summary, located in Part III of this document.
All documents used in selecting a response action for the Site
can be found in the Administrative Record File located in the
Morgan Memorial Library, 443 West Washington Street, Suffolk,
Virginia.
IV. SCOPE AND ROLE OF RESPONSE ACTION
The RI report documents the findings associated with the Site.
Based on the RI findings, EPA, in consultation with the State, has
determined that the Site does not pose an unacceptable risk to
human health and the environment. Therefore, a feasibility study
(FS) to evaluate cleanup alternatives was not required. EPA, in
consultation with VDWM, has determined that no remedial action is
required at the Site. Groundwater monitoring will be performed to
provide continued assurance that the Site does not pose an
unacceptable risk to human health and the environment.
V. SUMMARY OF SITE CHARACTERISTICS
This section discusses Site hydrological and geological
characteristics, summarizes sampling results performed during the
RI, identifies areas of concern, and discusses major fate and
transport phenomena of the contaminants found at the Site. Figure
3 depicts the locations of major sampling activities in the RI.
l. Site Characteristics
a. Regional Characteristics.
The topography in areas surrounding the Site is relatively
flat. This is a typical condition of the Coastal Plain
physiographic province in southeastern Virginia. Approximately 1.5
miles east of the Site is the Suffolk Scarp extending north-south.
The scarp was formed about 140,000 years ago during the Pleistocene
epoch when sea level was about 45 feet higher than it is today.
Regional surface water drainage is toward the Great Dismal Swamp.
Within the swamp, drainage is toward Lake Drummond, which is
located near the center of the swamp and has an area of
approximately 60 square miles. More locally, surface water drains
from the Site into the Pocosin Swamp, which widens to the
southeast. The Pocosin Swamp drains into the Washington Ditch of
the Great Dismal Swamp (Figure 2).
The geology around the City of Suffolk is principally related
to the great thickness of largely unconsolidated coastal plain
sediments in the region. The sediments generally dip and thicken
to the east. Beneath the Site, the coastal plain sediments, which
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Figure 3 - Sampling Locations and July 1992 Groundwater Elevations
0. \t«Ot*\JUlv«>
NOTE: SAMPLING LOCATIONS HR5-I2 < MRS 13
ARE APPROXIMATE.
FORMER
DETENTION
POND
BEN-5
CMP-5
HRS-IO
HRW-
MW-2
WATER TABLE ELEV. (FT.)
BENTHIC SAMPLING LOCATION
CREEK MONITORINS POST
SURFACE WATER. SEDIMENT SAhf LIN© LOCATION
NEW 6ROUNPHATER MONITORING WELL LOCATION
EXISTING 6ROLNDWATER MONITORING
WELL LOCATION
STREAM OR DITCH WITH FLOW DIRECTION
— -•- INTERMITTENT STREAM WITH FLOW DIRECTION
TREELINE
I
H
H
SCS ENGINEERS
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range in age from Holocene (recent) to early Cretaceous, attain a
thickness of approximately 1800 feet above basement meta-
sedimentary and meta-igneous rocks.
The Charles City Formation of Pleistocene age is the uppermost
formation at the Hosier Road Landfill site. The formation is
composed of sand, silt, and clay; grain size generally becomes
finer toward the surface. The Pleistocene formations are bounded
by unconformities and were deposited in fluvial-estuarine, bay,
barrier, and near-shore marine environments. The Pleistocene
formations contain various sediments of different characteristics.
The Pleistocene formations generally have an upward-fining
stratigraphy with localized coarser valley fill found at the base
of each sequence.
The Yorktown Formation may be characterized as a blue-gray and
green-gray sand interbedded with a sandy and silty blue-gray clay.
Generally, it contains abundant marine fossil shells and locally
contains glauconite and phosphate minerals.
Structural geology has played a minor role, compared to
stratigraphy, in shaping the geology of the region since Pliocene
time.
b. Local Characteristics.
. Hosier Road Landfill is located within the Dismal Swamp basin
and drains eastward to a small controlled outlet of the Dismal
Swamp Canal. Drainage within the Dismal Swamp basin occurs with
flatter, and longer-lasting flood flow peaks as compared to other
major basins in Virginia.
The Site is bounded on the north by an eastward flowing
perennial stream (unnamed stream N) which empties into the Pocosin
Swamp. A smaller intermittent stream (unnamed stream E) joins
unnamed stream N at the northeast end of the Landfill. Located
approximately 3/4 mile south of the Landfill, another unnamed
perennial tributary flows to the Pocosin Swamp. The Pocosin Swamp
itself discharges into the Washington Ditch of the Great Dismal
Swamp, which is located one mile southeast of the junction of the
two tributaries.
Four surface water bodies are currently located on the Site.
The sizes and locations of these water bodies can be seen on the
Site map presented in Figure 3. The Retention Basin is fed by
groundwater and has a fairly constant surface area. The former
detention pond and Detention Ponds 1 and 2 are fed by surface run-
off. During the summer, their surface areas and volumes decrease
substantially. By mid-summer, the former detention pond and
Detention Pond l are well vegetated and there is generally no
visible water.
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Several aquifers exist beneath the Site. The uppermost
unconfined aquifer (Columbia aquifer) is underlain by several
confined aquifers separated by intervening confining beds as shown
in Figure 4. The uppermost aquifers, the Columbia and Yorktown-
Eastover, and the intervening Yorktown confining unit, represent
the groundwater units of primary concern at the Site. The deeper
aquifers (The Lower Potomac) are isolated by clay confining units
that essentially restrict the vertical movement of constituents.
The Columbia aquifer is the most susceptible to contamination from
the vertical migration of hazardous constituents and has a
thickness of approximately 30 feet. The Columbia aquifer consists
of interbedded gravel, sand, silt, and clay. The hydraulic
conductivities of this upper aquifer vary from 0.59 feet per day to
4.14 feet per day across the Site, and the average value is 1.44
feet per day. The hydraulic conductivities were derived from slug
test data of wells HRW-1 to HRW-6. Groundwater underneath and in
the vicinity of the Site is present at depths ranging from 0 feet
to 15 feet below the existing topography, flows northeastward, and
discharges to the nearby streams.
2. summary of the RI Sampling Results and Areas of Concern
Surface water, sediment, and groundwater samples taken at
locations at and around the Site during the RI (Figure 3) were
analyzed for target pesticides, volatile compounds, semivolatile
compounds, and metals.
Although pesticides were the focus of the remedial
investigation, no pesticides were detected in any surface water,
sediment, or groundwater samples, including samples taken from a
groundwater monitoring well located immediately downgradient of the
pesticide disposal area (HRW-7). In addition, no organic compounds
were detected at levels that presented an unacceptable risk to
human health.
No metal contamination was detected above levels of concern in
seven of the nine monitoring wells. Slightly elevated levels of
arsenic were detected in two wells (HRW-3 and HRW-6) in the
northern section of the Landfill. Arsenic concentrations in
filtered samples collected from these wells were 71.9 and 55.7
ug/1, respectively, slightly above the Maximum Contaminant Level
(MCL) of 50 ug/1 established under the Safe Drinking Water Act.
In the second sampling round, which was conducted in October
1991, the level of chromium detected in an unfiltered sample from
one monitoring well (HWR-3) was 190 ug/1, exceeding the MCL of 100
ug/1. However, chromium was not detected in the filtered sample
taken from this well for the same sampling event. Chromium levels
in samples collected in the first sampling round (May 1991) from
this well were also well below the MCL (23.6 ug/1 in the unfiltered
sample and below the detection limit in the filtered sample).
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Figure 4 - Hydrogeologic Cross-Sections of the Hosier Road Landfill
w
50-
50-
-0-
20-
•0-
.50-
-------
Surface water sampling in unnamed streams N and E showed
arsenic and chromium levels well below the Virginia standards for
the protection of aquatic life. Also, the levels of these
compounds in the stream sediments are below the average levels in
soils of the eastern United States.
In addition, sampling of benthic community in a nearby stream
was conducted to provide further information for the determination
whether the Site has impacted the surrounding areas. The results
of the benthic sampling indicated low species diversity of benthic
organisms in a sample taken in the area immediately downgradient of
the Landfill near the confluence of the unnamed streams N and E.
However, subsequent surface water/sediment sampling at a nearby
location in this stream revealed the absence of contamination,
indicating the current Site condition was not likely the cause for
the low benthic species diversity.
An animal survey in areas around the Site was also conducted.
This study consisted of a comparison of animal species including
mammals, birds, reptiles, amphibians, and fish species in areas
around the Site to determine whether the Site has potentially
impacted the local animal community. The results showed that
animal species in different areas around the Site are similarly
diverse except at the benthic location from unnamed stream N in an
area northeast of the Site.
3. Fate and Transport Characteristics
Under the environmental conditions existing at the Site, it is
likely that the pesticides disposed at the Site in 1970 have
decomposed. Prior to burial, any pesticides exposed to sun light
would likely decompose rapidly through photolysis. As temperature
and Ph increase, the rate of hydrolysis of the pesticides
increases. At pH 8 and 20°C, a conservatively assumed condition
for the lime-containing pesticide pit, alkaline hydrolysis could
degrade 99.99% of the pesticides in 47 days to 12 years. The
reason for this wide range of degradation times is primarily the
variation in the rates of alkaline hydrolysis associated with
different pesticides disposed of at the Site. In addition to
photolysis and hydrolysis, biodegradation also breaks down the
pesticides quickly. For example, the biodegradation half-life for
Disulfoton and Thimet are 2.4 days and 3 days respectively.
Therefore, it is highly possible that the pesticides have been
significantly degraded by photolysis, alkaline hydrolysis, and
biodegradation processes since 1970, when they were disposed of at
the Site.
Metals, including arsenic and chromium, are persistent in the
environment. But metals tend to be adsorbed and remain adsorbed to
the soil in the subsurface system. As a result, metals are
relatively immobile in soil and groundwater. This property is
evident from the RI sampling results. Chromium and arsenic appear
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to be present at levels of concern in areas of the shallow aquifer
that are immediately downgradient of the Site (i.e., around HRW-3
and HRW-6). Although most groundwater in the shallow aquifer
discharges into unnamed streams N and E, no arsenic or chromium
contamination has been detected by surface water/sediment sampling.
In addition, levels of arsenic or chromium in monitoring well HRW-
4, which is located immediately downgradient of monitoring well
HRW-6, were well below the corresponding MCLs, indicating that the
groundwater contamination was only localized in areas immediately
downgradient from the Site.
VI. SUMMARY OF SITE RISKS
A human health risk assessment was conducted in accordance
with EPA risk assessment guidance for Superfund. The human health
risk assessment includes four major steps: identification of
chemicals of concern, exposure assessment, toxicity assessment, and
risk characterization.
Chemicals of Concern - Hazardous substances that were present
at levels exceeding chemical-specific applicable or relevant and
appropriate requirements (ARARs) or area background (upgradient)
levels were identified as chemicals of concern (Table 1). Since
dissolved metals are expected to be more mobile than total metals,
the identification of chemicals of concern in groundwater was based
on results of dissolved metal sampling.
Exposure Assessment - Major human potential exposure pathways
identified included groundwater pathways, soil and sediment
pathways, and surface water pathways. Other contaminant exposure
pathways were also considered in the risk assessment, but were
found to be insignificant pathways due to the unlikelihood of the
exposure scenarios, or insignificant exposure concentrations.
o Groundwater Pathway - The major exposure to groundwater
contamination is through drinking contaminated
groundwater. Shallow wells located downgradient of the
Site would present the most risk. As contaminated
groundwater in the shallow aquifer moves laterally
through the soil or vertically through the underlying
confining layer, certain contaminants, especially
metals, would likely be adsorbed or attenuated, thereby
reducing the risks with increasing distance downgradient
from the Site. This is the primary potential route of
exposure to contamination at the Site.
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Table 1 - List of Water Quality Standards for the Hosier Road Landfill
. . -•
Maximum
Obsarved
Contaminants Concentration
GROUND WATER INORGANICS
Aluminum
Arsenic '
Cadmium
Manganese
Nickel
2ine
SURFACE WATER INORGANICS
AJuminum
Arsenic
Cobalt
Manganese
Nickel
Zinc
Cyanide
("9/ir
206
71.9
5.7
396
43.5
59.4
8,200
6.9
74.3
264
80.2
99.2
26.4
SWC8 SWC8
Average GroundWater Maximum Maximum SurfaceWater SWC8 Freshwater
Observed Standard lor
Concentration Aquifers
(ug/l)" (ug/l)
82.1
19.3 50
0.40
91.9 50
—
26.4 50
1134.2
3.1
14.9
131.4
19.1
27.4
7.3
Contaminant Contaminant Standard for Criteria to Protect
Levels (MCLs) Level Goals Public Intake Aquatic Life (ug/l)
(ug/l) (Guidance) (ug/l) ' Chronic
— --
50 50
10 5
__
— _ — —
--
— — _ _
50 190
— —
100
varies w/ hardness
5000 47
5.2
Federal Fresh Water
Criteria to Protect
Aquatic Life (ug/l)
Acute Chronic
750 87
-- — _
— —
__
790-2500 88-280
65-210 59-190
22 5.2
f-
H
ARARs = Applicable or Relevant and Appropriate Requirements
• ug/l = mlcrograms/liter = ppb
SWC8 « State Water Control Board of Virginia
SW « Surface water
GW = Groundwater
NA *> Standard not applicable to this medium.
— = Data not available.
-------
o sediment Pathways - The Landfill is currently covered
with clean soil. Due to erosion, however, some refuse
exposed to the surface was observed during the RI.
Contaminants could move from the surface of the Site to
unnamed streams E and N, thus entering the food chain
through aquatic organism that may be ingested by humans.
o Surface Water Pathways - Contaminants in surface water
could enter into the human body system by ingestion of
potentially contaminated surface water or ingestion of
aquatic organisms in the surface water.
Exposure to chemicals of concern in each pathway is quantified
by multiplying an exposure point concentration by certain exposure
factors and averaging over a defined time period. In general, the
upper 95 percent confidence limit on the arithmetic average of
concentrations is used as the concentration factor in the exposure
calculation. The combination of the concentration factor and the
exposure factors should reflect the reasonable maximum exposure
that an individual would encounter at a site.
Summaries of mean and upper 95 percent confidence limit
concentrations for groundwater, surface water, and sediment are
presented in Tables 2 to 4.
Toxicity Assessment - In performing the toxicity assessment,
EPA examined chronic (long-term) exposures to the contamination
found at the Site. Risks were classified into carcinogenic risks
and non-carcinogenic risks.
EPA has developed slope factors, expressed in units of (mg/kg-
day)"1, to calculate an upper-bound estimate of the excess lifetime
cancer risk associated with exposure to carcinogenic chemicals.
The term "upper bound" reflects the conservative estimate of the
risk calculated from the slope factor. The slope factor is the
upper 95th percent confidence limit of the slope of the dose-
response curve and represents the probability of a response per
unit intake of the chemical. Slope factors are derived from the
results of human epidemiological studies or chronic animal
bioassay. If the slope factor is derived from animal data,
equivalent human doses are first determined. Slope factors can
then be multiplied by the calculated intake of the chemical of
concern to determine the cancer risk due to exposure.
In addition, EPA also evaluates the likelihood that a given
substance is carcinogenic in humans. This is reflected by the
"weight-of-evidence" assigned to that substance. A weight-of-
evidence classification is determined by experimental or
epidemiological studies involving exposure to the substance in
question. Weight-of-evidence is classified by capital letters
ranging in alphabetical order from "A" to "E," with "A" meaning
- 18 -
-------
Table 2 - Contaminants Detected in Groundwater Samples at the Hosier Road Landfill
Contaminants
INORGANICS - Total Metals
Aluminum
Arsenic
Cobalt •
Manganese
Nickel
Zinc
Cyanide
Concentration
(Upper 95% Limit)
(ug/l)*
2076
4.4
22.3
211.2
28.4
49.5
10.7
Mean
Concentration
(ug/i)
1134
3.1
14.9
131.4
19.1
27.4
7.3
Total
Number
of Samples
18
18
18
18
18
18
16
Number
of Samples
BQL**
4
14
16
1
15
10
14
Concentration in
Upgradient .
Surface Sample
HRS-4
(Mean)
423.5
BQL
BQL
16.75
BQL
16.8
BQL
H
I
* ug/l = micrograms/liter = ppb
** BQL = Below Quantification Limit.
-------
Table 3 - Contaminants Detected in Surface Water Samples at the Hosier Road Landfill
Contaminants
INORGANICS -
Aluminum
Arsenic
Manganese
Zinc
Concentration
(Upper 95% limit)
(ug/1)*
Dissolved Metals
115.1
36.7
163.7
38.1
Mean
Concentration
(ug/l)
82.1
19.3
91.9
26.4
Total
Number
of Samples
12
12
12
12
Number
of Samples
BQL**
10
7
0
3
Concentration in
Upgradient
Control Well
HRW-1
(mea'n)
142.5
BQL
127.9
17.8
* ug/l = micrograms/liter = ppb
** BQL = Below Quantification Limit.
o
eg
-------
Table 4
Contaminants Detected in Sediment Samples at the Hosier Road Landfill
Contaminants
INORGANICS
Aluminum
Arsenic
Chromium
Copper
Manganese
Vanadium
Zinc
Concentration
(95% Upper Limit)
(mg/kg)*
10258.0
5.1
8.8
4.6
23.2
19.1
52.4
Mean
Concentration
(mg/kg)
6949.3
2.4
6.1
3.3
17.9
12.6
33.9
Total
Number
of Samples
11
11
11
11
11
11
11
Number
of Samples
BQL**
0
8
3
8
0
4
2
Concentration in
Upgradient •
Sediment Sample
HRS-4
6410
BQL
4.7
BQL
23.6
17.9
38.6
CM
I
* mg/kg = milligrams/kilogram = ppm.
** BQL = Below Quantification Limit.
-------
evidence of carcinogenicity from exposure to the substance.
For chemicals with the potential to cause adverse health
effects other than cancer, EPA has developed levels that humans,
including sensitive subpopulations, can be exposed to on a long-
term daily basis without experiencing any adverse effects. These
levels are called reference doses (RfDs), and are expressed in
units of mg/kg-day. Estimated intakes of chemicals from
environmental media (e.g., the amount of a chemical ingested from
contaminated drinking water) can be compared to the RfD. RfDs are
derived from applicable human studies if adequate data are
available. If human data are not available, an animal study that
demonstrates the critical toxic effect of the chemical is selected.
A "no-observed-adverse-effect level" (NOAEL) is determined. The
NOAEL is divided by appropriate uncertainty factors to derive the
RfD. Uncertainty factors help ensure that the RfDs will not
underestimate the potential for adverse noncarcinogenic effects.
The ratio of the predicted daily exposure of the population to the
RfD of the contaminant is called the hazard quotient. The sum of
all hazard quotients of all contaminants for an exposure pathway is
termed the "Pathway Hazard Index." A Pathway Hazard Index less
than one (unity) indicates that non-carcinogenic risks present via
that exposure pathway are improbable.
Risk Characterization - Carcinogenic risks and non-
carcinogenic risks associated with major exposure pathways
discussed above were estimated.
Based on the assumption that exposure to onsite groundwater
occurs, an incremental carcinogenic risk of 7.5 x 10"4 was
estimated (Table 5) due to the presence of arsenic, the sole
carcinogenic contaminant present in the onsite groundwater. This
means there would be approximately 8 additional cancer cases per
10,000 exposed individuals. The estimated carcinogenic risks from
exposure to onsite groundwater is slightly above the acceptable
level (1 x 10~6 to 1 x 10~4j . The Pathway Hazard Index was
estimated at 1.8, primarily due to arsenic (Table 6). These
estimated risks are considered conservative since the groundwater
contamination was found within the boundary of the Landfill where
the use of the groundwater as a potable source is highly
improbable.
Although onsite groundwater in the northern section of the
Site presents slightly elevated risk, the offsite risks are
expected to be significantly reduced from the onsite risk'levels.
As the groundwater migrates offsite, the arsenic and metals in the
groundwater are adsorbed by the soils in the aquifer. Most of the
water in the Columbia aquifer, the shallow aquifer, discharges into
unnamed stream N, where surface water/sediment sampling showed no
contamination.
- 22 -
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Table 5 - Estimation of Carcinogenic Risks Associated With Ingestion of Groundwater
Contaminated With Metals (Dissolved) at the Hosier Road Landfill
Contaminants
INORGANICS
Aluminum
Aisenic
Manganese
Zinc
GDI'
(ug/kg/chy)
1.35E + 00
4.31E-01
1.92E + 00
4.47E-01
COI"
Adjusted lor
Absorption
1.35E + 00
4.31E-01
1.92E + 00
4.47E-01
SF
(tmg/kg/day)
1.75E + 00
—
Weight of
Evidence
A
D
D
Type ol
Cancer
_ _
Skin
--
—
SF
Source
IRIS
EPA
mis
H£A
Chemical
SF Bails Specific
(Med'a) Risk
— _ — —
Water 7.5E-04
__•
—
Total
Pathway
Risk
7.5E-04
' Upper 95% Contaminant Concentration X Human Intake Factor (assumes 70 kg adult drinks 2 liters ol water daily, 350 days per year lor 30 years (e.g., 0.01174 I/kg/day]).
•' Calcubiod deity inoke adjusted lor intestinal absorption efficiency here assumed to be 100 percent
CDl = Calculated daily inoke ol conamimnt based on upper 95% concentration limiland standard assumptions.
SF a Slope Factor
A = Human Carcinogen
D = Not cbssiliable as to human carcinogenicity.
IRIS * Integrated Risk Information System (January 24, 1992), National Medical Library.
EPA = EPA risk assessment personnel In comments to Draft R.I. Report.
— = Data not available.
n
-------
Tab!" 6 - Estimation of Chronic Hazards Associated With Ingestion of Groundwater
Contaminated With Metals (Dissolved) at the Hosier Road Landfill
Contaminants
CHRONIC HAZARDS
Aluminum
Arsenic
Manganese
Zinc
Daily Intake
(ug/kg/day)
2.25E»00 •
5.29E-01 •
2.52E«00 •
7.J3E-01 •
Daily Intake ••
Adjusted lor
Absorption
2.25E*00
S.29E-01
2.52E»00
7.23E-01
RIO
(ug/kg/day)
_ _
3.00E-01
1.00E»02
2.10E + 02 "•
RIO
Confidence
Level
Medium
Medium
_ _
Critical
Health
Effect
. .
Skin effects
CNS effects
_ .
RIO
Source
IRIS
IRIS
IRIS
HEA
RIO
Uncertainly
Adjustments
. _
3
1
_ -
Modifying
Factor
. _
1
1
• _
Haivd
Quotient
. .
I.78E-00
2.S2E-02
3.44E-03
Pttnxay
Hti&'d
Indei
1.6c>00
Mean Contaminani Concentration X Hum an Intake Factor (atiumet 70kg adult drinki 2 liters ol water dally lor 390 day* per year lot 30 yeari.l 0.0274 l/kg/d«yj).
'' Calculated daily intake adjusted for intestinal absorption efficiency here assumed to be tOO'percent.
• • * * RID is preliminary. Risk assessment for this substance is under review by EPA work group.
CNS • Central Netvous System
RIO • Reference Dote
IRIS • integrated Risk inlormaiion System (January 24, 1903). National MedicalLlbrary.
H£A - Health Effects Assessment Document,USEPA, 1986.
— • Data not available.
-------
Currently there are no residences in the area where
groundwater contamination has been observed. There are no
residential drinking water wells located directly downgradient of
the Site. Most residential drinking water wells are located
upgradient of the Site (south of the Site). Groundwater sampling
of monitoring wells located along the southeastern edge of the Site
revealed no contamination, indicating no contaminant migration in
this direction from the Site.
The potential risks resulting from consumption of surface
water in streams bordering the Site (Tables 7 and 8) , or from
consumption of aquatic organisms in these streams are well within
the acceptable levels (Tables 9 to 10) . Potential health risks
from accidental ingestion of sediments near the Site (Tables 11 and
12) "and from consumption of aquatic life sustained by sediment-
based food chains are minimal (Tables 9 and 10).
VII. DESCRIPTION OF THE SELECTED RESPONSE ACTION
The no-Action alternative was evaluated for the Site, as
required by the NCP, to establish a baseline for comparison with
other alternatives. EPA, in consultation with VDWM, selected the
No-Action alternative for the Site. Under the No-Action
alternative, no remedial action under CERCLA would be taken.
Groundwater monitoring will be performed to provide continued
assurance that no unacceptable risks to human health or the
environment occur.
VIII. BASIS FOR THE NO-ACTION ALTERNATIVE
EPA's determination concerning the need for remedial action at
a Superfund site is based upon site-specific information. As
described in this ROD, the Site poses a risk to human health only
in the event of consumption of contaminated groundwater existing in
certain areas within the Site boundary. No consumption of this
groundwater is occurring at this time and none is expected to occur
in the future. Also, the surface water sampling in the nearby
streams indicates that the contaminant levels are protective of
aquatic life. Thus, the No-action alternative is protective of
human health and the environment.
Sampling results indicating that there is no offsite migration
of contaminants, the low level risk associated with the on-site
contaminants, and the monitoring requirements which can identify
any future need for groundwater remediation, are major factors
contributing to the preference for the No-Action alternative.
EPA has determined that the risks associated with this Site do
not warrant remedial action under CERCLA. Since contaminants
remain at the Site, EPA will conduct a review within five years
after this ROD is issued to assure continued protection of human
- 25 -
-------
health and the environment.
IX. DOCUMENTATION OP SIGNIFICANT CHANGES
The Proposed Plan for the Suffolk City Landfill site was
released for public comment in August 1992. The Proposed Plan
identified a No Action Alternative as the preferred remedial
response action at this site. EPA reviewed all written and verbal
comments submitted during the public comment period. Upon review
of these comments, it was determined that no significant changes to
the remedy, as originally identified in the Proposed Plan, were
necessary.
- 26 -
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Table 7 - Estimation of Carcinogenic Risks Associated With Ingestion of Contaminated
Surface Water Near the Hosier Road Landfill
Contaminants
INORGANICS
Aluminum
Arsenic
Coball
Manganese
Nickel
Zinc
Cyanide
CDI •
ug/kg/day
2.47E + 01
5.24E-02
2.65E-01
2.51E + 00
3.38E-01
S.89E-OI
1.27E-01
CDI ••
Adjusted lor
Absorption
2.47E + 01
5.24E-02
2.65E-01
2.51E+-00
3.38E-01
5.89E-01
1.27E-01
SF Weight ol Type ol
1/mg/kg/day Evidence Cancer
__
1.75E + 00 A Skin
_ _ - -
D
— __ --
D
D
SF SF Basis
Source (Med'a)
IRIS
EPA Water
IRIS
IRIS
WIS --
IRIS
IRIS
Chemical- Total
Specific Pathway
Risk Risk
9.16E-05
—
--
--
__
9.26-05
• Contaminant Concentration (Upper 95% Limit) X Human Intake Factor (assumes 70 kg adult drinks 2 liters ol water da it/, 350 days per year tor 70 years, (e.g., 0.0119 I/kg]).
•' Calcubted daity innke adjusted lor Intestinal absorption efficiency here assumed to be 100 percent
COI a Calculated daily in&ke of conaminont based on upper 95% concentration limit and standard assumptions.
SF a Slope (actor
A = Human Carcinogen
0 = Not cbssiliedas to human carclnogenicily.
EPA s EPA risk assessment personnel in comments to Draft R.I. Report
IRIS » Integrated Risk Information System (January 24, 1992). National Medical Library.
- - n Data not available.
01
-------
Table 8 - Estimation of Chronic Hazards Associated With Ingestion of Contaminated
Surface Water Near the Hosier Road Landfill
CoMa minims
CMRONiC HAZARDS
Alu minum
Arsenic
Cobalt
Manganese
NicKel
Zinc
Cyanide
Daily Intake
ug/kg/day
3.llE*01 '
8.49E-02 '
4.08E-01 '
3.60E«00 •
5.23E-01 '
7.J1E-01 •
2.00E-OI '
Dally Intake "
Adjusted tor
Absorption
3.I1E»OI
6.49E-02
4.08E-01
3.80E + 00
S.23E-01
7.5IE-OI
2.00E-OI
Critical
RIO Confidence Health
(ug/xg/diy) Level Effect
3.00E-01 Medium Skin effect I
I.OOEtOi Medium CNS eKectt
2.00EtOt Medium Oeer. body & organ wgl
2.10E + 02
2.00E«OI Medium Thyroid & myelln eHecU
' Mean Contaminant Concentration X Human Intake Factor (assumes 70 kg adult drinks 2 liters ol water daily. 350 days per
•• Calculated daily intake ad|usted lor intestinal absorption efficiency here assumed lo be 100 percent.
RfO
Source
IRIS
IRIS
IRIS
IRIS
IRIS. •
HEA
IRIS
year lor 30 years
RIO
Uncertainly Modifying
Adjustments Factor
3 1
t 1
300 1
100 9
[e.g. .0.0274 I/kg/day).
Maura
Quotient
J.83E-01
3.60E-02
2.02E-02
3.98E-03
I.OOE-02
Painoay
ritttra
tndei
3.6E-CI
PfD • Reference Dose
CNS • Cenval Nervous System
IRIS • Integrated Risk Information System (Januvy 14,1992). National Medical Library.
HEA - Health Elects Assessment Document, USEPA, 1988.
I
00
-------
Table 9 - Estimation of carcinogenic Risks Associated With Ingestion of Contaminated Fish
Near the Hosier Road Landfill
Com- i-nants
INORGANICS
Aluminum
Arsenic
Cobalt
Manganese
Nickel
Zinc
Cyanide
COl '
ug/kg/day
t.B?E«00
1.74E-02
O.OOE»00
O.OOEtOO
1.20E-OI
2.09E-OI
O.OOE»00
' COl "
Adjusted for
Absorption
1.67E«00
1.74E-02
O.OOEtOO
O.OOEtOO
I.20E-01
2.09E-01
O.OOEtOO
Fish Siocon-
centralion
Factor
(l/Xg fish)
10
44
47
47
_ _
Human Intake •••
Factor SF
(kg fish/kg/day) l/mg/kg/day
S.OOE-05
9.00E-05 t.73E*00
9.00E-05
9.00E-OS
9.00E-OS
9.00E-05
9.006-05
Weight of
Evidence
„ ^
A
- -
0
--
0
0
Type of SF
Cancer Source
IRIS
Skin EPA
IRIS
IRIS
IRIS
IRIS
IRIS
Chemical- Total
SF Bails Specific Patn»ay
(Media) Risk Risk
_ _ •. -
Water 17IE-07
_-
_. . -
_-
- -
. _
7.3E-07
Contaminanl Concentration in Surface Water (Upper 95% Limit} X Sloeoncenlralion Factor X Human Intake Factor.
'' Calculated daily intake adjusted for inteitinal aoiorption efficiency here assumed to be 100 percent.
•" Human intake lactor (kg lisn/kg/day) - 0.0065 (kg fish/day) X 1/70 (kg/adult).
COl • Calculated daily Intake of contaminant based on upper d5% concentration limit and standard assumptions.
SF • Slope lacier
A « Human Carcinogen
0 • Not Classifiable at to human carclnogencity.
iFtlS - Integrated Risk Inlormation System (January 24, 1992). National Medical Library.
EPA • EPA risk assessment personnel In comments to Draft R.I. Report.
-------
Table 10 - Estimation of Chronic Hazards Associated With Ingestion of Contaminated Fish
Near the Hosier Road Landfill
Fish Biocon-
Conaminanu
CHRONIC HAZARDS
Aluminum
Arsenic
Codau
h>«ngann«
Nickel
Zinc
Cyanioe
Daily intake
ug/Vg/day
1.02*00'
1. 2X-02 '
1.346-03'
i.iee-02'
e.OE-02'
i.iffi-oi •
6.57E-W •
Daily Intake"
Adjusted lor
Absorptbn
1.0Z»00
1.2X-02
I.34E-03
1.IE-02
a.oe-02
•1.16E-01
6.S7E-04
RfO
(ug/kg/day)
..
..
2.20E«02
I.OCEtOI
2.10£*02
J.OCEtOI
Confidence
Level
. .
Medium
._
Medium
Medium
--
Medium
Critical
Health
Effect
._
Skin eNects
__
CNS affects
Oecr, body & organ wgl.
--
Thyroid & myelln effects
RfO
Source
IRIS.
IRIS
IRIS
IRIS
IRIS
HEA
IRIS
RfO .
Uncertainty
Adjustments
_„
3
• ..
1
300
--
.100
Modifying
Factor
_„
I
• .
1
1
--
5
Huard
Quotient
..
--
..
S.3S-05
8,083-03
S.5Z-04
3.29E-OJ
centration
Factor
OA9 fish)
10
44
_.
.-
47
"
.
Human Intake
factor ""
(kg fishAg/aayl
9CCE-OJ
90CE-OS
9.0X-OJ
90CE-05
90CE-05
9.0CE-05
9.0CE-OJ
Mean Conuminant Concentration X Fish Bioconcentration Factor X Human Intake Factor.
' • Calculated daily inuke adjusted lor Intestinal absorption efficiency here assumed to be 100 percent.
••• Humin Intake lactor (kg (ish/Vg/day) - 0.0369 (kg liih/day) X 1/70 (kg/adult).
R!O • Reference Dose
CNS • Central Nervous System
iRiS • Integrated Risk Information System (January 24, 1699. National Meo.cal Library.
O
01
-------
Table 11 - Estimation of Carcinogenic Risks Associated With Ingestion of Contaminated
Sediments Near the Hosier Road Landfill
Calculated Daily Intake
from Ingestion of Sediment
Calculated Carcinogenic Risk
from Ingestion of Sediment
Contaminants
Average Daily
Lifetime Intake *
(mg/kg/day)
Potency
Factor
(mg/kg/day)-1
Lifetime*
Carcinogenic
Risk
Weight of
Evidence
Chronic
Risk
INORGANICS - Total Metals
Aluminum
Arsenic
Chromium
Copper
Manganese
Vanadium
Zinc
1.61E-02
8.01 E-06
1.38E-05
7.22E-06
3.64E-05
3.00E-05
8.23E-05
1.75E+00** 1.40E-05
* Assume 15 kg child eats 200 mg sediment per day, 350 days per year for 6 years, then,
as a 70 kg adult, eats 100 mg sediment per day, 350 days per year for 24 years.
** Potency Factor provided by EPA risk assessment personnel in comments to Draft R.I. Report.
A = Human Carcinogen
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Table 12 - Estimation of Non-Carcinogenic Risks Associated With Ingestion of Contaminated
Sediments Near the Hosier Road Landfill
Contaminants
INORGANICS - Total Metals
Aluminum
Arsenic
Chromium
Copper
Manganese
Vanadium
Zinc
Calculated Daily Intake
from Ingestion ol Soil (mg/kg/day)
Adults • Children ••
Upper 95% Upper 95%
Limit Mean Limit Mean
1.41E-02 9.52E-03 1.31E-01 8.90E-02
6.996-06 3.29E-06 6.53E-05 3.07E-05
I.21E-05 8.36E-06 1.13E-04 7.81E-05
6.306-06 4.52E-06 5.89E-05 4.22E-05
3.18E-05 2.45E-05 2.97E-04 2.29E-04
2.62E-05 1.73E-05 2.44E-04 1.6IE-04
7.18E-05 4.64E-05 6.71E-04 4.34E-04
Allowable Daily Intakes
lor Adults and Children
(mg/kg/day) Data
Subchronic Chronic Source
3.00E-01 IRIS
1.00E+00 IRIS
' 3.70E-02 '3.70E-02 HEA
-- 1.00E-01 IRIS
2.00E+02 HEA
2.10E-01 2.10E-01 HEA
Hazard lnd«*
Adults* Children"
(mg/Vg/day) (mg/kg/day)
Subchronic Chronic Subchronic Chronic
1.IOE-05 -- 1.02E-04
8.36E-06 -- 7.81E-05
1.70E-04 1.22E-04 1.59E-03 1.14E-03
2.45E-04 -- 2.29E-03
8.63E-08 -- 8.06E-07
3.42E-04 2.21E-04 3.19E-03 2.07E-03
Assume 70 kg adult eats 100 mg sediment per day, 350 days per year lor 24 years.
Assume 15kg child oats 200 mg sediment per day, 350 days per year lor 6 years.
IRIS
HEA
Integrated Risk Information System (January 24, 1992). National Medical Library.
Health EHeets Assessment Document. USEPA, 1986.
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