United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R10-93/063
September 1993
ve/EPA Superfund
Record of
Hanford 1100-Area (DOE),
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50272-101
REPORTDOCUMENTA~ON
PAGE
11. REPORT NO.
EPA/ROD/R10-93/063
~
3. A8c1pIent'a Ace_Ion No.
4.
Title and Builth..
SUPERFUND RECORD OF DECISION
Hanford llOO-Area (DOE), WA
First Remedial Action
A~hor(a)
~
Report D8t8
09/24/93
,
7.
I.
P8rformlng Organization Rept. No.
II.
P8rformlng Organization Name and AcId-
10
Project TuklWortc Unit No.
11. Contr8Ct(C) or Granl(O) No.
R
(0)
12. ~ng Organization Name and Add,..a
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report I Pwlod Cov8l'8d
Agency
800/800
14.
15. Buppl8m8nlary Not.
PB94-964624
11. Ab8tr8Ct (Umh: 200 worda)
The 5-square mile Hanford 110-Area (DOE) site is located in the southern part of a 560-
square mile Federal facility located along the Columbia River in southeastern
washington. The facility is located north and west of the cities of Richland,
Kennewick, and Pasco, an area commonly known as the Arid Lands Ecology (ALE) Reserve.
This area covers 120 square miles and is managed by DOE for ecological research. Land
use in the area is predominantly agricultural. The Tri-Cities area is a major
population center with 100,000 residents. In 1943, operations began at Hanford as part
of the Army's "Manhattan Project" to produce plutonium for nuclear weapons; however DOE
currently operates facilities throughout the site. The site contains the central
warehousing, vehicle maintenance, transportation distribution center, and the ALE
Reserve Headquarters, formerly a NIKE missile base and control center, located on the
northern slope of Rattlesnake Hills. Historical documentation indicates that several
individual waste units may have released a variety of contaminants onsite to the soil
and ground water. During the detailed site investigations, quantitative evaluations of
the waste units indicated that soil and ground water were contaminated by VOCs, PAHs,
PCBs pesticides, metals, and other organics. The site has been divided into four OUs
(See Attached Page)
17. Document AnaIya18 a. Da8crtptora
Record of Decision - Hanford llOO-Area (DOE), WA
First Remedial Action
Contaminated Media: soil, gw
Key Contaminants: VOCs (benzene, PCE, TCE), other organics (PAHs, PCBs, pesticides),
metals (arsenic, chromium, lead), inorganics (asbestos)
b.
Id8nIIft8rs1Open-Endad Tarms
c.
COSA" FlaJ4lGroup
11. Avallabllhy Statamanl
111. Security CIaaa (nile Report)
None
31. Security CIaaa (Thia P~ga)
None
21. No. of Pagea
80
22. Prica
(Sea AHSJ.Z311.18)
S-,,..,lVCtlorla on "'vwu
OPTIONAL FORM 272 (4-77)
(Formarty NTIS-35)
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EPA/ROD/RIO-93/063
Hanford 1100-Area (DOE), WA
First Remedial Action
Abstract (Continued)
for remediation: 1100-EM-1, 1100-EM-2, 1100-EM-3, and 1100-rU-1. The 1100-EM-1 OU
consists of the Battery Acid Pit, Paint Solvent Pit, Antifreeze and Degreaser Pit,
Antifreeze Tank Site, Discolored Soil Site, Horn Rapids Landfill (HAL), and Ephemeral
Pool. This ROD addresses the risk associated with onsite contamination in the soil and
ground water. The primary contaminants of concern affecting the soil and ground water are I
VOCs, including benzene, PCE, TCE; other organics, including PAHs, PCBs, and pesticides;
metals; including arsenic, chromium, and lead; and other inorganics, including asbestos.
~
The selected remedial action for this site includes excavating approximately 840 tons of
soil contaminated with bis (2-ethylhexyl) phthalate (BEHP) from the Discolored Soil Site,
with offsite incineration at a RCRA-licensed facility; excavating approximately 636 yd3 of
PCB-contaminated soil from the Ephemeral Pool and the HRL, with off site disposal in a
TSCA-permitted landfill; removing more than 5,495 yd3 of contaminated soil and debris from
the 1100-EM-2, 1100-EM-3, 1100-rU-1 OUs, with offsite disposal; conducting soil sampling
in excavations to determine if cleanup goals have been met; backfilling excavated areas
with clean fill; capping the HRL to prevent contact with the contained asbestos; placing a
notice on the deed identifying this area as an aSbestos-containing landfill; allowing for
natural attenuation of the TCE-contaminated ground water; monitoring ground water; and
implementing institutional controls, including deed and ground water use restrictions.
The estimated present worth cost for this remedial action is $10,840,000, which includes
an estimated annual O&M cost of $65,300 for 30 years.
PERFORMANCE STANDARDS OR GOALS:
The soil remedial action objectives are based on MTCA State standards, and include benzene
0.5 mg/kg; PCE 0.5 mg/kg; TCE 0.5 mg/kg; toluene 40 mg/kg; xylenes 20 mg/kg; PAHs 1 mg/kg;
PCBs in Ephemeral Pool soil and soil from OUs 1100-EM-2, 1100-EM-3, and 1100-rU-1 1 mg/kg;
PCBs in the HRL 5.2 mg/kg; hexavalent chromium 1,600 mg/kg; and lead 250 mg/kg. The
objective for natural attenuation of ground water is TCE 0.5 mg/l, which is based on SDWA
MCLs and is expected to be reached within 25 years.
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Record of Decision
~- - --- .." .
. . --- .-
._-- --- - .
o
USDOE Hanford 1100 Area
"
Hanford Site
Richland, Washington
September 1993
Washington State Department of Ecology A U.S. Environmental Protection Agency A U.S. Department of Energy
,,"';/"',
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DECLARA TION OF THE RECORD OF DECISION
SITE NAME AND LOCATION
USDOE Hanford 1100 Area
Hanford Site
Benton County, Washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial actions for the USDOE Hanford 1100
Area, Hanford Site, Benton County, Washington, which were chosen in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), and to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the Administrative Record for this site.
The State of Washington concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response actions selected in this Record of Decision (ROD), may present
an imminent and substantial endangerment to the public health, welfare, or the environment.
DESCRIPI'ION OF THE SELECTED REMEDY
The selected remedy for the 1100 Area NPL Site addresses actual or threatened releases at
the four 1100 Area Operable Units: 11OQ-EM-1, 1100-EM-2, 1100-EM-3, and 1100-IU-l.
. The major components of the selected remedy include:
1100-EM-l Operable Unit
. Capping the Horn Rapids Landfill.
. Offsite disposal of PCB contaminated soils.
. Offsite incineration of soils contaminated with bis (2-ethy1hexy1)phthlalate.
.Y
. Natural attenuation of groundwater that currently exceeds MCL's and monitoring
for compliance. .
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. Continuation of institutional controls for groundwater and land use at the Horn
Rapids Landf1ll.
llOO-EM-2, EM-3 and IU-l Operable Units
"
. Offsite disposal of soils, debris and structures contaminated with solvents, PCBs
and other hazardous substances.
. Continuation and expansion of groundwater monitoring.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, will comply with
federal and state requirements that are legally applicable or relevant and appropriate to the
remedial action, and is cost effective. This remedy utilizes permanent solutions to the
maximum extent practicable for this site, and satisfies the statutory preference for remedies
that employ treatment that reduces toxicity, mobility, or volume as a principal element.
Alternative treatment technologies were evaluated for this site, but are not included in the
selected remedy.
Because this remedy will result in hazardous substances remaining on site above health-based
levels, a review will be conducted within 5 years after commencement of remedial action to
ensure that the remedy continues to provide adequate protec.tion of human health and the
environment.
~
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Signature sheet for the Record of Decision for the USDOE Hanford 1100 Area Final
Remedial Action between the United States Department of Energy and the United States
"Environmental Protection Agency, with concurrence by the Washington State Department of
Ecology.
J agoner
anager, Richland Operat ~
nited States Department of Energy
r hD fct3
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Signature sheet for the Record of Decision for the USDOE Hanford 1100 Area Final
Remedial Action between the United States Department of Energy and the United States
Environmental Protection Agency, with concurrence by the Washington State Department of
Ecology.
t./;u!ff' ~~
Gerald A. Emison
Acting Regional Administrator, Region 10
United States Environmental Protection Agency
f- 7- 'f -7"3>
Date
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Signature sheet for the Record of Decision for the USDOE Hanford 1100 Area Final
Remedial Action between the United States Department of Energy and the United States
Environmental Protection Agency, with concurrence by the Washington State Department of
Ecology.
'I)~ [tL~/r
Drusilla Butler
Program Manager, Nuclear and Mixed Waste Program
Washington State Department of Ecology
jfpr 3D /qv
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TABLE OF CONTENTS
DECLARATION OF THE RECORD OF DECISION. . . . . . . . . . . . . . . . . . . . . .
DECISION SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
SITE NAME, LOCATION, AND DESCRIPTION. . . . . . . . . . . . . . . . . .. 1
SITE HISTORY AND ENFORCEMENT ACTIONS. . . . . . . . . . . . . . . . .. 4
HIGHLIGHTS OF COMMUNITY PARTICIPATION. . . . . . . . . . . . . . . .. 7
SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY. ., 8
SITE CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 9
SUMMARY OF SITE RISKS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
REMEDIAL ACTION OBJECTIVES. . . . . . . . . . . . . . . . . . . . . . . . . . . 51
DESCRIPTION OF ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . . . . . . 55
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES. . . . . .. 61
SELECTED REMEDY. . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . . 65
STATUTORY DETERMINATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
DOCUMENTATION OF SIGNIFICANT CHANGES. . . . . . . . . . . . . . . . . 69
RESPONSIVENESSS~ARY .. ................................70
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DECISION SUMMARY
INTRODUCTION
The u. S. Department of Energy's Hanford Site was listed on the National Priorities List
(NPL) in July 1989 under authorities granted by the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) of 1980 as amended by the
Superfund Amendments and Reauthorization Act (SARA) of 1986. The Hanford Site was
divided and listed as four NPL Sites: the 1100 Area, the 200 Area, the 300 Area, and the
100 Area.
\.
In accordance with Executive Order 12580 (Superfund Implementation) and the NCP, the
U.S. Department of Energy (DOE) performed a Remedial Investigation (RI) for the
liDO-EM -1 Operable Unit, which characterized the nature and extent of contamination in
groundwater and soils near the lloo-EM-l. A baseline risk assessment, comprised of a
human health risk assessment and an ecological risk assessment, was conducted as part of the
RI to evaluate current and potential effects of 1100-EM-l contaminants on human health and
the environment. DOE also performed a focused Remedial Investigation (RI) for the
remaining three 1100 Area operable units (l1oo-EM-2, 11oo-EM-3, and 11oo-IU-l), which
characterized the nature and extent of contamination in groundwater and soils near these
Units. A qualitative baseline risk assessment (an evaluation of overall potential risk from
these operable units made by comparing possible waste site contaminant levels with existing
State and Federal health-based guidelines), was conducted as part of the focused RI to
evaluate potential effects of contaminants on human health and the environment.
I. SITE NAME, WCATION, AND DESCRIPTION
The Hanford Site is a 560-square mile Federal facility located along the Columbia River in
southeastern Washington, situated north and west of the cities of Richland, Kennewick, and
Pasco, an area commonly known as the Tri-Cities (Figure 1). The 1100 Area NPL Site is
located in the southern portion of the Hanford Site, and covers less than 5 square miles.
Operable Units 1100-EM-l, 1100-EM-2, and 11oo-EM-3 are located in the southernmost
portion of the Hanford Site and contain the central warehousing, vehicle maintenance, and
transportation distribution center for the entire Hanford Site (Figure 2). 11oo-IU-l is located
on the northeastern slope of the Rattlesnake Hills, approximately 24 kilometers (km) (15
miles) from the 1100 Area. The site is a former NIKE missile base and control center, and
is now used for the Arid Lands Ecology (ALE) Reserve Headquarters.
The land surrounding Hanford is used primarily for agriculture and livestock grazing. The
major population center near Hanford is the Tri-Cities, with a combined population of nearly
100,000. The southwestern area of Hanford, covering 120 square miles, is designated as the
Arid Lands Ecology Reserve and is managed by DOE for ecological research.
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Operable Unit Location Map
1100 - EM - 1, 1100 - EM - 2,
1100 - EM - 3 & 1100 - IU - 1
Operable Units
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11100 AREAl
LEGEND:
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Outline and Designation of
Operable Units
Subunit Location and Designation
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500 1000 IotETERS
....
1000 2000 3000 FEET
nOO-3 .
Operable Units 110O--EM-1, 2 & 3 with Subunits.
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The North Richland Well Field is located 0.8 kIn east of the 1171 building and is used to
supplement city of Richland water supplies. Columbia River water is pumped to the well
field and then percolates through the soil creating a groundwater mound. The City then
extracts water from this mounded area as needed to supplement the water supply from the
water treatment plant. This procedure reduces turbidity and improves water quality for
industrial and residential usage.
Semi-arid land with a sparse covering of cold desert shrubs and drought-resistant grasses
dominates the Hanford landscape. Forty percent of the area's annual six and one quarter
inches of rain occurs between November and January. In part due to the semi-arid
conditions, no wetlands are contained within the boundaries of the 1100 Area NPL Site.
The Columbia River is located approximately one mile east of the 1100 Area. The 1100
Area is not within the 100 year flood plain of the river.
ll. SITE HISTORY AND ENFORCEMENT ACTIONS
The Hanford Site was established during World War II as part of the Army's "Manhatten
Project" to produce plutonium for nuclear weapons. Hanford Site operations began in 1943,
and DOE facilities are located throughout the Site and the City of Richland. Much of the
land that Hanford now occupies was ceded to the government by treaty with various Native.
American tribes. Certain portions of the Site are known to have cultural significance and
may be eligible for listing in the National Register of Historical Places.
In 1988, the Hanford Site was scored using EPA's Hazard Ranking System. As a result of
the scoring, the Hanford Site was added to the NPL in July 1989 as four sites (the 1100
Area, the 200 Area, the 300 Area, and the 100 Area). Each of these areas was further
divided into operable units (a grouping of individual waste units based primarily on
geographic area and common waste sources). The 1100 Area NPL site consists of four
operable units (llOO-EM-1, l1oo-EM-2, lloo-EM-3, and llOO-IU-l).
In anticipation of the NPL listing, DOE, EP A, and Ecology entered into a Federal Facility
Agreement in May 1989. This agreement established a procedural framework and schedule
for developing, implementing, and monitoring remedial response actions at Hanford. The
agreement also addresses Resource Conservation and Recovery Act (RCRA) compliance and
permitting.
The North Richland well field has been of particular interest during the course of the 1100
Area investigation. Located 0.8 km east of the 1171 building, the well field is still used to
supplement city of Richland water supplies. Initial concerns focussed on the impact of
possible migration of potential contaminants from the 1100 Area to the well field.
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The 1l00-EM-1 Operable Unit contains several individual waste sites. These sites are:
. 1100-1 (The Battery Acid Pit): An unlined, sand-filled sump, or french drain
approximately 30 m (100 ft) from the southwest corner of the 1171 Building, used for
disposal of waste acid from vehicle batteries. During it$ use, the pit was
approximately 1.8 m (6 ft) in diameter and 1.8 m deep. The pit is no longer visible
because it was filled and graded to match the surrounding surface when it was
removed from service. Historical documents record an estimated 57,000 liters (L)
[15,000 gallons (gal)] of battery acid wastes may have been disposed of during its
operating years (1954 to 1977).
\
. 1100-2 (The Paint and Solvent Pit): A semicircular depression located
approximately 1.6 kIn (1 mile) north of the 1171 Building. Originally a sand and
gravel pit, the site was used during the period between 1954 through 1985 for the
disposal of construction debris generated during demolition of Hanford Site facilities.
Principal components of the waste include concrete rubble, asphalt, and wood debris.
Undocumented disposal of waste paint, solvent, and paint thinner is also reported to
have occurred at this site. The pit has an approximate diameter of 108 m (354 ft) and
a depth of 1.2 to 1.8 m (4 to 6 ft).
. 1100-3 (The Antifreeze and Degreaser Pit): A shallow, roughly circular
depression located approximately 1.6 kIn (1 mile) north of the 1171 Building on the
west side of the Hanford Rail Line. Originally a sand and gravel source for
construction activities on the Hanford Site, it was used during the period of 1979 to
1985 as a disposal site for waste construction material, principally roofmg and
concrete rubble. The pit is approximately 76 m (250 ft) in diameter and 1.8 to 2.4 m
(6 to 8 ft) deep. Occasional disposal of waste antifreeze and degreasing solutions
from the 1171 Building was suspected, but not documented, at this location.
. 1100-4 (The Antifreeze Tank Site): A former underground storage tank used for
waste vehicle antifreeze. This tank was emptied in 1986, cleaned, and removed due
to suspected leakage. No evidence of leakage was detected when the tank was
removed.
. UN-llOO-6 (The Discolored Soil Site): A patch of oily, dark stained soil located
in the eastern end of an elongate east-west oriented depression approximately 610 m
(2,000 ft) northwest of the 1171 Building on the west side of the Hanford Rail Line.
The depression extends over an area of approximately 0.2 hectares (0.4 acres); the
~ctua1 area of discolored soil covering an area of perhaps 1.8 by 3.1 m (6 by 10 ft).
The source of the soil discoloration appears to be the isolated, unauthorized disposal
of contents of one or more containers of liquid material to the ground surface. No
record exists that identifies the nature or origin of the waste of the material deposited
at the site.
d
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. The Horn Rapids Landfill: Located north of Horn Rapids Road near its
intersection with Stevens Drive, the Horn Rapids Landfill (HRL) extends over
approximately 20 hectares (50 acres) of the 600 Area. Originally a borrow pit for
sand and gravel, it was used as a landfill primarily for office and construction waste,
asbestos, sewage sludge, fly ash, and reportedly, numerous drums of unidentified
organic liquids. Classified documents were also incinerated at a bum cage located at
the northern edge of the landfill. from the late 1940's into the 1970's. The landfill is
situated in generally flat terrain. Five disposal trenches have been identified at the
site through a study of historic aerial photographs, onsite investigations, and
geophysical surveys. Surface debris consisting of auto and truck tires, wood, metal
shavings, soft drink cans and bottles, and other small pieces of refuse are scattered
across the site. A single trench, the western-most of the identified waste disposal
trenches, was posted with signs warning that the trench contained asbestos.
. The Ephemeral Pool: A long, narrow, manmade depression located along the
western edge of the asphalt-paved 1171 Building parking area. The depression acts as
a drainage collection point for precipitation runoff flowing from the parking area
surface. Overall dimensions are approximately 6.1 m (20 ft) wide (east-west
direction) by 183 to 213 m (600 to 700 ft) in length (north-south direction). The
Ephemeral Pool was designed to collect runoff from the parking area and direct it to a
central culvert located approximately at the lengthwise mid-point of the depression.
The ll00-EM-2 Operable Unit is located in the southwest corner of the Hanford Site near the
north border of the City of Rich1and, Washington. The main feature is the 1171 Building, a
vehicle service maintenance and repair facility constructed in the early 1950's. The main
waste sites in 1l00-EM-2 are several used oil tanks, steam pad and hoist ram storage tanks,
and a hazardous waste staging area. Removal of an antifreeze underground storage tank
(UST) from the 1171 Building in 1986 was addressed in the 1100-EM-l RIfFS.
The l100-EM-3 Operable Unit is located about 600 meters (1000 feet) northeast of
l100-EM-2. llOO-EM-3 contains approximately 20 permanent structures, some of which
date back to 1951, that have been used for maintenance, warehouse, service support, and
offices in support of Hanford operations. These buildings form the Hanford 3000 Area.
Key waste sites in llOO-EM-3 include several hazardous waste storage and staging areas, a
used oil UST, and contaminated soil from a previously removed UST. Four fuel UST's
were removed from this area in 1991.
llOO-IU-1 is located on the northeastern slope of the Rattlesnake Hills, approximately 24
kilometers (km) (15 miles) from the 1100 Area. The site is a former NIKE missile base
consisting of structures which supported missile launch, control, and maintenance functions,
as well as living quarters for base personnel, and storage buildings for hazardous substances
used in the maintenance of the physical plant and missile operations. All base facilities are
abandoned with the exception of the former barracks which are used for the Arid Lands
Ecology (ALE) Reserve Headquarters.
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ill. HIGHLIGHTS OF COM1\1UNITY PARTICIPATION
DOE, Ecology, and EP A (the Parties) developed a Community Relations Plan (CRP) in April
1990 as part of the overall Hanford Site restoration. The CRP was designed to promote
public awareness of the investigations and public involvement in the decision-making process.
The CRP summarizes concerns that the Parties are aware of based on community interviews.
Since that time, the Parties have held several public meetings and sent out numerous fact
sheets in an effort to keep the public informed about Hanford cleanup issues. The CRP was
updated in 1993 to enhance public involvement.
'1
\.
The final RIfFS Report and Proposed plan were made available to the public in both the
Administrative Record and the Information Repositories maintained at the locations listed
below on May 24, 1993:
ADMINISTRATIVE RECORD (Contains all project documents)
U.S. Department of Energy
Richland Field Office
Administrative Record Center
740 Stevens Center
Richland, Washington 99352
EP A Region 10
Superfund Record Center
1200 Sixth Avenue
Park Place Building, 7th Floor
Seattle, Washington 98101
Washington State Department of Ecology
Administrative Record
719 Sleater-Kinney Road SE
Capital Financial Building, Suite 200
Lacey, Washington 98503-1138
INFORMATION REPOSITORIES (Contain limited documentation)
University of Washington
Suzzallo Library
Government Publications Room
Mail Stop FM-25
Seattle, Washington 98195
d
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Gonzaga University
Foley Center
E. 502 Boone
Spokane, Washington
99258
Portland State University
Branford Price Millar Library
Science and Engineering Floor
SW Harrison and Park
P.O. Box 1151
Portland, Oregon 97207
DOE Rich1and Public Reading Room
Washington State University, Tri-Cities
100 Sprout Road, Room 130
Richland, Washington 99352
The notice of the availability of these documents was published in the Seattle PI/Times, the
Spokesman Review-Chronicle, the Tri-City Herald, and the Oregonian on May 23, 1993 and
again on June 13, 1993. The public comment period was held from May 24, 1993, through
July 9, 1993. In addition, a public meeting was held on June 30, 1993. Additional
advertisements ran in the Tri-City Herald on June 27 and 29, 1993. At the meeting,
representatives from DOE and EP A answered questions about the project. A response to the
comments received during the public comment period, including those raised during the
public meeting, is included in the Responsiveness Summary, which is part of this ROD.
This decision document presents the selected remedial action for the 1100 Area at the
Hanford Site, Richland, Washington, chosen in accordance with CERCLA, as amended by
SARA, and to the extent practicable, the NCP. The decision for this site is based on the
Administrative Record.
IV. SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY
The cleanup actions described in this ROD address all known current and potential risks to
human health and the environment from the 1100 Area. This ROD addresses contaminated
soils found at l100-EM-l and the contaminated groundwater in the vicinity of the Horn
Rapids Landfill. In addition, this ROD requires surface and soil cleanups in the other three
operable units.
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v. SITE CHARACTERISTICS
A. Site Geology and Hydrology
The Hanford Site is located in the Pasco Basin, a topographic and structural basin situated in
the northern portion of the Columbia Plateau. The plateau is divided into three general
structural subprovinces: the Blue Mountains; the Palouse; and, the Yakima Fold Belt. The
Hanford Site is located near the junction of the Yakima Fold Belt and the Palouse
subprovinces. A generalized geologic structural map is included as Figure 3.
\.
The 1100 Area is located along the southeastern margin of the Hanford Site, adjacent to the
Columbia River. The.geologic structure beneath the 1100 Area is similar to much of the rest
of the Hanford Site, which consists of three distinct levels of soil formations. The deepest
level is a thick series of basalt flows that have been warped and folded, resulting in
protrusions that crop out as rock ridges in some places. Layers of silt, gravel, and sand
known as the Ringold formation form the middle level. The uppermost level is known as the
Hanford formation and consists. of gravel and sands deposited by catastrophic floods during
glacial retreat. Both confined and unconfined aquifers can be found beneath Hanford. A
generalized stratigraphic column is shown in Figure 4. .
1. Unconfined Aquifer
The unconfined aquifer below the 1100 Area occurs between the water table and the
underlying silt aquitard, approximately 95 to 107 m (310 to 350 ft) above mean sea level
(amsl). The aquifer occurs within the lower Hanford formation and the upper portion of the
middle Ringold Formation. The thickness of the unconfined aquifer varies; the maximum
thickness observed was 13 m (44 ft) near the 1171 Building and the minimum was 5 m (16
ft) near the Horn Rapids Landfill. Outside of the lloo-EM-l Operable Unit, fewer data are
available to map the unconfmed aquifer thickness. In general, the thickness appears to
increase toward the Columbia River.
Groundwater recharge to the unconfined aquifer below the 1100 Area is primarily from the
Yakima River located several miles west and southwest of the site. The river appears to
discharge directly to the unconfined aquifer along the Horn Rapids Reach below Horn Rapids
Dam. Precipitation and irrigation infiltration, and, potentially, unconfined aquifer flow
beneath the Yakima River provide additional recharge to the 1100 Area groundwater. The
volume of recharge from inftltrating precipitation is approximately 10 to 40 times less than
the recharge from the westward groundwater inflow.
To the east of the 1100 Area, the North Richland well field artificially recharges the
unconfmed aquifer. Water from the Columbia River is allowed to percolate through the soil
at the well field to provide treatment of turbid river water and enhance the well field capacity
(see Figure 2 for well field location). This is a major source of recharge to the aquifer and
causes groundwater mounding that extends west to the vicinity of the 1171 Building.
-------
I
t
Pasco Basin
l
I
l,
I Hanford SiI8
,~ Boundary
I
BOundary7
~~
\
\
I
Baalt 0uIr::r0p
~ SycI"me
+ AnticlIne
L1 Monocline
~
~
Depreaion in
Top of Baal!
Figure 3.
-------
Thickness Range
( meters)
6 - 15
5 - 14
1 - 11
not determined
in 1100 Area
not determined
in 1100 Area
LEGEND:
I :.::::.:::~::::.:::~
.:.;".::. .0.-;'...:.
'0,,:: .0. 00"::".
~::~::~
-;:::;.. "':- r=;.. -
!~ \?~ \?:I
Sand
Silty Sand
-..
Eolian
Sand
,-
Hanford
formation
(Pasco Gravels )
Ringold
Fonnation
-L
Saddle
Mountains
Basalt
Sandy Gravel/Gravelly Sand
Figure 4
Hydrogeologic Units
-
-------
'"r.~-r --..
----
. . " . . .
:~::."'~::: :~
'.. . '.. . .
. . .
. '. . '. .
. . . . " .,
. . .. . . .
:~::.. :~::.':~
0,0..0' ","'"cO '0
: "," .:. :.:;; ,'.:. ::..;~ ..-
~~~
~~:=~
DIll
Vadose Zone
"
..
Unconfined Aquifer
Silt Aquitard
Confined Aquifer
Lower Silt Aquitard
-------------
Bedrock
Silty Sandy Gravel/Silty
Gravelly Sand
Clay /Silt/Sandy Sand
Basalt
Generalized Hydrostratigraphic Column for the 110O-EM-1 Operable Unit
-don 'JII"'''.don
-------
However, because the well field is recharged intermittently, the mound can dissipate between
periods of recharge. Monthly totals for recharge at the well field during 1988 and 1989
ranged from about 75,000,000 L (20,000,000 gal) to 1,500,000,000 L (400,000,000 gal).
2. Commed Aquifer
A silt aquitard was identified during drilling throughout the llOO-EM-1 Operable Unit. The
aquitard was encountered within the interval from 91 to 102 m (299 to 333 ft) amsl. Wells
drilled to elevations lower than 91 m (299 ft) amsl invariably intercepted the aquitard. There
is, however, uncertainty regarding the continuity of this layer. A possibility exists for the
aquitard to be discontinuous due to erosion that may have occurred before the overlying
sediments were deposited.
The upper confined aquifer occurs immediately below the silt aquitard. Information on this
aquifer is limited, as the UQO-EM-l RI hydrogeological investigation focused primarily on
the vadose zone and unconfmed aquifer. The available information does not show evidence
that the confined aquifer is contaminated.
The groundwater potentials measured in 1100 Area confined aquifer wells indicate that flow
is apparently toward the east. There is also flow upward into the silt aquitard that occurs
above the confined aquifer. It is unlrnown if North Richland well field operations have
significant affects on the flow observed in this aquifer, although minor fluctuations observed
in water levels measured in one well indicate that at least some minor effect is likely.
The sediments encountered in the confined aquifer ranged from silty sand to sandy gravel of
the middle Ringold Formation. Rising head slug tests yielded hydraulic conductivity
estimates of .034 mId (1.0 ft/d) and 0.086 mid (0.30 ft/d), respectively, indicating that at
least in these two locations the hydraulic conductivity is generally lower than in the
unconfined aquifer (see Table 1).
The upper confined aquifer was identified at the HRL, and to the south nearer the
1171 Building. The vertical thiclrness of the upper confined aquifer may vary from a few
meters up to 10 m (30 ft), depending on the continuity of silt strata in the middle Ringold
unit.
-------
Table 1. Measured and Estimated Saturated Zone Hydraulic Properties
Horizontal Vertical
Hydrogeologic Hydraulic Hydraulic Storage Porosity
Unit Conductivity Conductivity Coefficient (effective)
(mid) (mId)
Unconfined Aquifer
Hanford Formation 400 - 520 40 - 50- .02 - .37- .20 - .33-
(near HRL)
Hanford Formation 3350 - 15000 330 - 1500- .02 - .37- .20 - .33-
(near 300 Area)
Ringold Formation 10 - 72 2-5 .02 - .37 .11 - .30-
Silt Aquitard .001 - .03 .0001 - .003- .20 - .33-
Confined Aquifer 10-72 2-5 .11 - .30-
,
*
based on general reported values at the Hanford Site or extrapolated from nearest
available value
B. Nature and extent of Contamination
Investigative Approach
The investigations in the llOO-EM-l Operable Unit were conducted in a two-phase approach,
with tasks proceeding methodically. The investigative methodology was to start off with a
radiation survey of all of the sites, then do surface geophysics (e.g. electromagnetic induction
and ground-penetrating radar). Next, a soil gas survey using temporary probes was
performed and surface samples were taken. All of the information gathered to date was used
to site vadose zone borings and groundwater wells. Other tasks in phase one were the
determination of soil and groundwater background values and air monitoring during intrusive
investigations. The information gathered from this first phase was evaluated to determine the
tasks for the second phase. The tasks in the second phase were similar to those in the first,
although they were much more focused.
For the other three operable units, the investigative approach was quite different, and much
more streamlined. In the fall of 1992, it was determined that llOO-EM-2, lloo-EM-3 and
1100- IU -1 were candidates for an accelerated evaluation that could enable all of the 1100
-------
Area operable units to be addressed simultaneously. A limited field investigation/focused
feasibility study (LFI/FFS) was undertaken for those three operable units.
The results of the 1100 Area investigations are described in the following paragraphs.
1. llOO-EM-l Soils
Batterv Acid Pit
A geophysical survey was conducted over the area where the pit had been to find the exact
location of the pit and locate soil gas probes and a vadose zone boring. The pit was located,
along with other buried objects including a water line and some wires. Five temporary soil-
gas probes were installed at the Battery Acid Pit as part of the first phase. No contamination
was detected in the soil-gas samples. A single boring was made at the Battery Acid Pit.
This borehole yielded one sample from the surface and seven from the subsurface.
Substances identified (Le., detected above background) in surface soil samples are: calcium,
copper, lead, magnesium, mercury, nickel, sodium, and zinc. Substances identified in
subsurface samples are: arsenic, copper, lead, mercury, potassium, sodium, vanadium, and
zinc. Maximum values of all soil analytes were compared with background to identify
contaminants. These were further screened to remove essential micronutrients (Le., at the
concentrations measured, aluminum, calcium, iron, magnesium, potassium, and sodium are
nontoxic and do not pose a human health or an environmental threat). The remaining soil
contaminants are considered to be of potential concern and were evaluated further in the risk
assessment. These soil contaminants, and their maximum concentrations, are presented in
Table 2. No additional work was performed during the second phase.
Paint and Solvent Pit
The geophysical survey was conducted over the floor of the pit. Rubble and other
construction debris were found. Sixty-two temporary soil-gas probes were installed,
sampled, and analyzed during phase one. One area of relatively high readings of
tetrachloroethene (PCE) was found in the southwest comer of the site close to the end of a
service road which extends back toward a railroad storage yard located immediately north of
the Paint and Solvent Pit site. Concentration values peaked at 727 p.g/L PCE with values
steeply dropping in all directions away from the high. Areal distribution of the positive soil-
gas readings suggested the potential for an isolated, shallow accumulation or small surface
spill of solvent within the pit. No other volatile contaminants were detected during the soil-
gas survey.
Four boreholes drilled at this site yielded 4 surface samples and 29 subsurface soil samples.
One of these boreholes was drilled in the location of the high PCE reading described above.
In addition, soil samples were obtained at 20 surface locations within the 1100-2, Paint and
Solvent Pit. Substances identified in surface soil samples are: calcium, chromium, copper,
lead, potassium, sodium, thallium, chlorobenzene, tetrachloroethene, trichloroethene,
-------
Table 2. Summary of 1100-EM-l Operable Unit Soil Contaminants and
Maximum Contaminant Concentrations. (sheet 1 of 2)
Contaminant Battery Paint and Antifreeze and Antifreeze Discolored Horn Rapids Ephemeral
Acid Pit Solvent Pit Degreaser Pit Tank Site Soil Site Landfill Pool
(1100-1) (1100-2) (1100-3) (1100-4) (UN-II00-6) (mg/kg) (mg/kg)
(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)
Antimony -- -- -- -- -- 15.6 --
Arsenic 3.2 -- -- 5.8 -- 6.6 --
Barium -- -- -- -- -- 1,320 --
Beryllium -- -- -- 0.93 -- 1.3 --
Cadmium -- -- -- -- -- 2.4 --
Chromium -- 16.8 14 -- -- 1,250 --
Cobalt -- -- 17.8 -- -- 42.5 --
Copper 37.9 24.4 31.7 19.8 -- 1,280 --
Cyanide -- -- -- -- -- 0.56 --
Lead 266 94.6 26.4 5.7 22.1 854 54.2
Manganese -- 366 436 -- -- 501 --
Mercury 0.39 . -- -- -- -- 1.3 --
Nickel 20.9 -- -- -- -- 557 --
Selenium -- -- -- -- -- 0.97 --
Silver -- -- -- 2 -- 7.7 --
Thallium -- 0.48 0.4 0.48 -- 3.1 --
Vanadium 118 -- -- -- -- 101 --
Zinc 100 56.6 60 63.8 111 3,160 67.5
.
-------
Table 2. Summary of 1100-EM-l Operable Unit Soil Contaminants and
Maximum Contaminant Concentrations. (continued)
Contaminant Battery Paint and Antifreeze and Antifreeze Discolored Horn Rapids Ephemeral
Acid Pit Solvent Pit Degreaser Pit Tank Site Soil Site Landfill Pool
(1100-1) (1100-2) (1100-3) (1100-4) (UN-II00-6) (mg/kg) (mg/kg)
(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)
BEHP -- -- -- -- 25,000 -- --
Beta-HCH -- -- -- -- -- 0.094 --
Chlordane -- -- -- -- 1.86 -- 2.8
Chlorobenzene -- 0.006 -- -- -- -- --
DDT -- 0.16 -- -- 0.17 1.98 --
Endosulfan II -- -- -- -- -- 0.11 0.16
Endrin -- -- -- -- -- 0.42 0.039
Heptachlor -- -- -- -- 0.065 0.02 0.029
2-Hexanone -- -- -- -- 0.053 -- --
Naphthalene -- -- -- -- -- 8.2 --
PCB's -- -- -- -- -- 100 42
Tetrachloroethene -- .0.035 -- -- -- 0.006 --
Trichloroethene -- 0.006 -- -- -- -- --
1,1,1- -- -- -- -- 0.035 -- --
Trichloroethane
-------
l,l-dichloroethene, and xylene. Contaminants identified in subsurface samples are: calcium,
copper, lead, magnesium, manganese, potassium, sodium, zinc, 4,4'-DDE, 4,4'-DDT, and
tetrachloroethene (see Table 2). No additional work was performed during the second phase.
Antifreeze and De&easer Pit
The geophysical survey was conducted over the floor of the pit. Rubble and other
construction debris were found. Forty-three soil-gas samples were collected from temporary
probes in the Antifreeze and Degreaser Pit. No contaminants were detected during the soil-
gas investigation. Twenty-three surface samples were collected and twenty-four subsurface
samples were obtained from four boreholes at the 1100-3, Antifreeze and Degreaser Pit.
Substances identified in surface soil samples are: aluminum, calcium, chromium, copper,
lead, sodium, and thallium. Substances identified in subsurface samples collected during the
Phase I investigation. are: aluminum, calcium, cobalt, copper, iron, magnesium, manganese,
sodium, and zinc (see Table 2). No additional work was performed during the second phase.
Antifreeze Tank Site
In November 1989, a hole was cut through the concrete floor of stall 89 inside the 1171
Building to allow sampling of the waste site. Thirteen vadose zone samples were collected
and analyzed for the full suite of chemical analyses including ethylene glycol. Only a single
sample detected ethylene glycol, at a concentration of 2.6 parts per million (ppm). Other
than this single exception, only inorganic contaminants were detected at this site. Substances
identified in subsurface samples are: aluminum, arsenic, beryllium, calcium, copper, lead,
potassium, silver, sodium, thallium, zinc, and ethylene glycol (see Table 2). No additional
work was performed during the second phase.
Discolored Soil Site
Fifteen surface samples were obtained from this site during the first phase. Substances
identified in surface soil samples are: lead, potassium, zinc, alpha-chlordane, gamma-
chlordane, 4,4'-DDE, bis(2-ethylhexyl)phthalate, heptachlor, 2-hexanone, di-n-octyl
phthalate, and 1,1, I-trichloroethane (see Table 2).
Fourteen temporary soil-gas probes were installed at the Discolored Soil Site to depths
ranging between 0.46 and 1.22 m (1.5 and 4 ft) during the Phase n investigation. The
purpose was to investigate the possibility of a vadose zone source for contaminants identified
during surface soil sampling/analysis. Soil gas samples did not identify any contaminants.
No other work was performed during the second phase.
Ephemeral Pool
Two surface samples taken from the soil within the Ephemeral Pool area. Substances
identified in surface soil samples are: lead, zinc, Aroclor-1260, alpha-chlordane, gamma-
-------
chlordane, Endosulfan n, Endrin, and heptachlor (see Table 2). Six surface samples were
obtained during Phase n to delineate the lateral extent of organic contamination at the
Ephemeral Pool. The soil samples collected during the Phase n RI were submitted for PCB
and pesticide analyses. Laboratory results confirm the presence of alpha and gamma
chlordane in concentrations of 210 to 1100 ILg/kg and 330 to 1700 ILg/kg, respectively.
Positive results for PCB's (Aroclor 1260) were obtained from two of the seven samples with
concentrations of 11,000 and 42,000 ILg/kg. Contaminants identified in surface soil samples
collected during Phase n are: Chlordane (alpha and gamma), Endosulfan n, Endrin., and
PCB's (total).
Horn Raoids Landfill (HRL)
The purpose of the first phase geophysical investigation was to obtain information regarding
waste materials buried at the site, to locate waste disposal structures (pits and trenches), to
identify any underground utilities crossing the site, and to identify any other waste disposal-
related features existing within the landfill. Outside of five identified waste disposal
trenches, no other major waste accumulations were detected, ~though the entire surface of
the subunit is littered with miscellaneous debris. Soil-gas studies were performed at the HRL
and in surrounding areas to assist in siting permanent groundwater monitoring wells and to
survey the vadose zone for a possible contaminant source contributing to groundwater
contamination. Two hundred and eleven temporary soil-gas extraction points were installed
in the landfill area. Trichloroethene (fCE); 1, 1, I-trichloroethane (TCA); and PCE were
found within the HRL. Results of this study were used to determine the siting of subsequent
groundwater monitoring wells. A total of 36 permanent soil-gas extraction points were
installed within the limits of the HRL. TCE was detected at 17 locations, with
concentrations ranging from 3 to 233 parts per billion by volume (Ppbv).
After the geophysi~ and soil-gas surveys were done, 55 surface soil samples were taken.
Substances identified in surface soil samples are: aluminum, arsenic, barium, beryllium,
cadmium, calcium, chromium, cobalt, copper, cyanide, iron, lead, magnesium, mercury,
nickel, potassium, silver, sodium, thallium, zinc, Aroclor-1248, Aroclor-1254, Alpha-
Chlordane, 4,4'-DDD, 4,4'-DDE, 4,4'-DDT, Heptachlor, 2-methylnaphthalene, naphthalene,
and tetrachloroethene (see Table 2).
Fifty-five subsurface samples were taken from fourteen boreholes drilled in the Horn Rapids
Landfill area. Substances identified in subsurface soil samples are: aluminum, antimony,
arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, cyanide, iron,
lead, .magnesium, mercury, nickel, potassium, silver, sodium, thallium, zinc, and Aroclor-
1248.
During the second phase investigation, additional soil-gas surveys, geophysical surveys,
surface soil sampling, and subsurface soil sampling were performed. During the second-
phase soil-gas survey, a total of 53 additional, temporary, sampling probes were installed and
analyzed to delineate the TCE plume previously identified in the vicinity of HRL. TCE was
-------
detected at concentrations from 2 to 255 parts per billion by volume (Ppbv) in 36 of the 53
probes. The highest TCE concentrations were obtained just outside the disturbed portions at
the eastern limits of HRL. Results obtained from this stage of soil-gas monitoring were used
in the siting of additional groundwater monitoring wells installed during the Phase IT
investigation.
The additional geophysical survey was performed to further delineate disposal trench
boundaries identified during the first geophysical surveys of the site and to search. for an
accumulation of drums containing organic solvents said to have been buried in the HRL.
Areas identified by the geophysics that might represent an accumulation of drums were
investigated with test pits (described below).
Eight surface samples were taken to identify the areal extent of PCB contamination in the
HRL. Fifteen samples were taken from the surface to further characterize 2 surface
depressions in the HRL. Thirteen subsurface samples were taken from the test pits dug as a
result of the geophysical survey. Substances identified during this phase that were not
detected during the first phase include Endosulfan n and Endrin in surface samples and
manganese and Dieldrin in subsurface samples. Also found during excavation of the test pits
were various types of debris (automotive, construction, etc.) and two small deposits of
chemicals. One (white crystalline powder) was identified as sodium bisulfate and the other
(bright purple-stained soil) was identified as potassium pennanganate.
2. Groundwater
During the first phase of the HOO-EM-l Operable Unit investigation, seventeen new wells
were drilled in the llOO-EM-l operable unit between August 1989 and January 1990.
During phase two, seven additional wells were drilled between January and June 1991. With
the addition of existing wells, 30 to 35 wells were sampled each quarter from January 1990
through October 1992, for a total of 11 rounds of sampling. Initially, the scope of the
groundwater investigation was very broad and so the first two rounds of samples were
analyzed for compounds on the Target Analyte List (TAL), Target Compound List (TCL), as
well as RCRA and primary and secondary drinking water parameters. After the first two
rounds, the scope was adjusted to reflect refinements in the conceptual site model.
Trichloroethylene- (fCE-) contaminated groundwater was found both upgradient and
downgradient of the Landfill. The TCE plume is approximately 1.6 kilometers (1 mile) long
and 0.3 kilometer (0.2 mile) wide and is moving in a northeasterly direction. Figure 5
shows the approximate outline of the TCE plume as of March 1992. In addition, the
groundwater monitoring network for the Landfill has detected nitrates and Technetium-99 (a
radionuclide). A review of all available information indicates that contamination has moved
onto the Site via the groundwater. An adjacent facility is investigating soil and groundwater
contamination as an independent action in accordance with the Washington State Model
Toxics Control Act (MTCA).
-------
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41\1DJ' 4fJID
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/
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/
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TCE
Data and Approximate Plume Extent, March 1992.
LEGEND:
- 5 ppb TCE
TCE (ppb )
I
1\1
/
... METtJIS
~...
2000 fEET
-------
Maximum values of all groundwater analytes were compared with background values to
identify contaminants. These groundwater contaminants, and their maximum concentrations,
are presented in Table 3. These were further screened to remove essential micronutrients.
At the concentrations measured, aluminum, barium, calcium, iron, magnesium, potassium,
sodium, and zinc are nontoxic and do not pose a human health or an environmental threat.
The remaining contaminants are considered to be of potential concern and were evaluated
further in the risk assessment.
3. llOO-EM-2, llOO-EM-3, and llOO-IU-l Soils and Debris
Between October 1992 and January 1993, a limited field investigation was performed at
llOO-EM-2, llOO-EM-3 and UOO-IU-l. Initially, the Hanford waste information data
system was reviewed for data on waste types, handling practices, or known soil or
groundwater contamination was reviewed. This identified 64 sites. Then, historical
information including aerial photographs and as-built construction drawings were reviewed.
All of the sites were inspected and, whenever possible, knowledgeable personnel were
interviewed. During this process, an additional 18 sites were identified, bringing the total to
82. At this point, pertinent regulatory aspects [e.g., underground storage tanks (UST's)
regulated under the state UST program] and previous characterizations of sites, were
reviewed for indication of potential releases and spills of contaminants to the environment.
This resulted in the identification of 32 sites that are currently, or are a candidate for,
management under other regulatory programs. Of the remaining sites, 43 are considered to
be likely or potential sites of releases or spills, and 7 are sites of known releases or spills.
Once the environmental and regulatory information for each site was evaluated, each site was
placed in one of four categories, and the last three categories were evaluated for cleanup:
. Already remediated or currently under regulation by the State or EPA under a
statute other than the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) or the Model Toxics Control Act (MTCA). (20 sites)
. Pending or a candidate for regulation by the State or EP A under a statute other
than CERCLA or MTCA. (12 sites)
. Not a candidate for regulation under another statute and is the site of a likely or
potential release or spill of contaminants to the environment. (43 sites)
. Not a candidate for regulation under another statute and is the site of a known
release or spill of contaminants to the environment. (7 sites)
The categories of sites evaluated for cleanup are further broken down by waste or site type
and are summarized below:
-------
Table 3. Summary of ll<>O-EM-l Operable Unit Groundwater Contaminants and
Maximum Contaminant Concentrations. (sheet 1 of 2)
Analyte (units) MCL Level Background Maximum
Concentration
Observed
Aluminum (Ppb) 50-200 152 1350
Barium (Ppb) 1000 60.5 132
Calcium (Ppb) NA 74600 197000
Chromium (Ppb) 100 7.8 57.5
Copper (Ppb) 1300 5.22 71.9
Iron (Ppb) 300 820 2050
Lead (Ppb) 50 13.7 25.3
Magnesium (Ppb) NA 20200 42100
Manganese (Ppb) NA 390 352
Nickel (Ppb) 100 (proposed) 15 140
Silver (Ppb) 50 4 11.7
Potassium (Ppb) NA 7140 13900
Sodium (Ppb) NA 29500 56900
Zinc (Ppb) NA 8.3 223
Ammonia (ppm) NA 0.15 0.87
Fluoride (ppm) 4 0.5 3.7
Chloride (ppm) 250 22.1 110
Phosphate (as P) (ppm) NA 1 1.9
Sulfate (ppm) 255 42.5 89.6
Nitrate (as N) (ppm) 10 12.3 61
Methylene Chloride (Ppb) 5 (proposed) 1 13
Acetone (Ppb) NA 10 31
Chloroform (Ppb) 100 1 5
1,1 , I-Trichloroethane (Ppb) 200 1.2 3
-------
Table 3. Summary of ll00-EM-l Operable Unit Groundwater Contaminants and
Maximum Contaminant Concentrations. (continued)
Analyte (units) MCL Level Background Maximum
Concentration
Observed
Tetrachloroethene (Ppb) 5 1 4
Toluene (Ppb) 2000 (proposed) 1 2
Diethylphthalate (Ppb) NA 10 34
Gross Alpha (PCilL) 15 8.4 12.2
Gross Beta (PCi/L) 50 18 95.4
-------
Site
Number
Underground Storage Tanks
Soil Sites with Metals
Soil Sites with Organics
Spills
Septic Systems
Debris Sites
PCB Transformers/Pads
Others
Landfills
21
6
12
5
6
2
6
2
2
ApJ>roximate Volume (fotal)
380 Cubic Yards
440 Cubic Yards
940 Cubic Yards
125 Cubic Yards
3,600 Cubic Yards
10 Cubic Yards
410 Cubic Yards
No Estimate
Approximately 5 Acres
Contaminants of potential concern that are evaluated in the risk assessment are:
1, 1,1- Trichloroethane, PCBs, Carbon Tetrachloride, Aniline, Furfuryl Alcohol,
Dimethylhydrazine, Acetone, Chromium Trioxide, Chromium-containing Paints, Sodium
Dichromate, Trichloroethylene (fCE), Benzene, Toluene, Ethylbenzene, Xylenes, Lead,
Tetrachloroethene (PCE), TPH (gasoline), TPH (diesel), and PAR's.
VI. SUMMARY OF SITE RISKS
The approach for evaluation of site risks for the llOO-EM-1 consisted of evaluating the
results of the remedial investigations to develop an initial list of Contaminants of Potential
Concern (COPC) (fable 4). The COPC list was further evaluated and screened in
accordance with the Hanford Site Baseline Risk Assessment Methodology (HSBRAM) and in
consultation with EP A Region 10. HSBRAM was developed by DOE, in consultation with
EPA and Ecolgy. HSBRAM is based on EPA's Risk Assessment Guidancefor Supeifund
(RAGS) and other EPA guidance (both national and Region 10). HSBRAM was developed
to provide direction on flexible, ambiguous, or undefined aspects of the various guidances,
while ensuring that Hanford Site risk assessments remain consistant with current regulations
and guidance. A Baseline Residential Scenario Risk Assessment (BRSRA) and a Baseline
Industrial Scenario Risk Assessment (BISRA) were conducted in accordance with the
HSBRAM. In addition, potential ecological risks were evaluated. The results of the human
health and ecological risks are discussed below.
A. Human Health Risks
Adverse effects resulting from exposure to chemical contaminants are identified as either-
carcinogenic (i.e. causing development of cancer in one or more tissues or organ systems) or
non-carcinogenic (i.e., direct effects on organ systems, reproductive and developmental
effects). In the BISRA, risks for current and future industrial use have been evaluated. In
the BRSRA, future residential land use was evaluated. The human risk receptors included
-------
Table 4. Summary of Contaminants of Potential Concern
for the llOO-EM-l Operable Unit.
Contaminant 1100-1 1100-2 110Q-3 110Q-4 Discolore Horn Ephemer Ground-
d Soil Rapids al Pool water
Site UN. Landfill
11 QO.6
Antimony X
Arsenic X X X
Barium X
Beryllium X X
Chromium X X X
Copper X
Lead8 -- 8
Manganese X X X
Nickel X X
Thallium X
Vanadium X X
Zinc X
BEHP X
Beta-HCH X
Chlordane X X
DDT X
Heptachlor X X X
PCB's X X
Nitrate X
TCE X
-------
on-site long- and short-term workers, and hypothetical future on-site residents. Exposure
conditions for these receptors were assumed to correspond to a wide range of activities
including residential, recreational and industrial.
1. Chemicals of Concern
Data collected during the RI were used to identify chemicals present at llOO-EM-l. The
previous section of this ROD presents sampling results by media. All chemicals were
included in the assessment unless: a) it was not detected in the media sampled; b) toxicity
reference values (i.e. reference dose [RID] or cancer slope factors [SF's]) have not been
developed for the chemical; or c) the chemical was identified as an essential nutrient.
Eight COC's were identified based on BISRA and BRSRA reasonable maximum exposure
(RME) scenarios. In this case, cac's are defined as those with potential exposures
presenting a carcinogenic risk greater than 1 x 1
-------
Table 5. Summary of Residential Scenario Intakes Based on Maximum Contaminant
Concentrations for the Soil Ingestion, Fugitive Dust Inhalation, and Dermal
Exposure Pathways at Specific tlOO-EM-t Operable Subunits.
Co ntaminant Pathway
Soil Ing estion (mg/kg-d ) Fug itive Dust Inhalation (mg/kg-d ) Dermal Exposure (mg/kg -d )
Noncarcinog enic Carcinogenic Noncarcinogenic I Carcinogenic Noncarcinogenic Carcinog enic
T etrachloroethen e 1 3 x 1 0.7 5 6 x 1 0.8 -- 0 1 4 x 1 0.,0 1 7 x 1 0.7 7 2 x 1 0-8
A rsen ic 1 3 x 1 0.5 5 4 x 1 0.11 -- 0 3 2 x 1 0.98 2 7 x 1 0.7 1 1 x 1 0.7
Chromi um 5 2 x 1 0.5 -- b -- 0 4 .4 x 1 0.8 1 1 x 1 0.6 -- b
Lead -- 0 -- d __0 .- d -- 0 -- d
B EHP 9 3 x 1 0.2 4 .0 x 1 0.2 --0 5 3 x 1 0.5 1 1 x 1 0.2 4 7 x 1 0.3
Chlordan e 6 9 x 1 0.11 2 9 x 1 0.11 -- 0 4 .0 x 1 0-9 8 .8 x 1 0.11 3 .8 x 1 0.11
Chlordane 1 .0 x 1 0.5 4 5 x 1 0.6 -- 0 1 6 x 1 0.8 1 .3 x 1 0.5 5 .7 .x 1 0.6
PCBs -- 0 6. 6 x 1 0.5 -- 0 2 .4 x 1 0.7 -- 0 8 .6 x 1 0-5
Arsenic 2 .4 x 1 0.5 1 .0 x 1 0.5 -- 0 2 6 x 1 0.88 5 2 x 1 0.7 2 2 x 1 0.7
Beryl lium 4 .8 x 1 0.11 2 1 x 1 0.11 -- 0 1 7 x 1 0'8 1 .0 x 1 0.7 4 .4 x 1 0.8
Ch ro mium 4 6 x 1 0.3 .- b -- 0 1 7 x 1 0.5 9 9 x 1 0.5 u b
Lead -- 0 -- d -- 0 -- d -- 0 -- d
PCBs -- 0 1 6 x 1 0.4 .- 0 1 3 x 1 0.11 -- 0 2 1 x 1 0-4
T etrachloroethene 2 2 x 1 0.8 9 6 x 1 0-9 -. 0 8 .0 x 1 0.1 1 2 8 x 1 0.8 1 2 x 1 0.8
8' ntakes adjusted for 30 % ab sorption of inhaled arsenic
bNot considered carcinog enic by this route of exposure or pathway
0Rf D not available to evaluate intake for this pathway
dSF not available to evaluate intake for this pathway
-------
Table 6. Summary of Contaminant Intakes for Homegrown Vegetables in the Garden Pathway at Specific
1100-EM-I Operable Subunits Based on the Maximum Contaminant Concentrations in Soil.
Potatoes
(mg/kg-d)
Total Contaminant Intake
(mg/kg-d)
Carcinoganic
Carcinogenic
Carcinogenic
e
~~ y y
BEHP 1.4 x 10'\ 6.2 X 10.2 1.1 X 10'\ 4.7 X 10.2 1.5 X 10.2 6.5 X 10.3 6.4 X 10.2 2.6 X 10.2 3.3 X 10'\ 1.4 X 10'\
Chlordene 5.6x10.1 2.4 x 10.7 4.6x10.6 2.0x10.6 1.2x10.6 5.1 X 10.8 7.1 X 10.6 3.0x10.6 1.2x10.4 5.5x10'.
Chlordane 8.4x10.7 3.6x10.7 7.0x10'. 3.0x10.6 1.Bx10.6 7.8x10.8 1.0x10.4 4.5x10.6 1.9 x 10.4 8.3x10'.
PCBs 1.0x10.4 7.8x10.6 1.1 x 10'. 4.5x10'. 2.3 x 10"
Arsenic 4.0 X 10.8 II 1.6 X 10.8 II 3.9 X 10.7 e 5.1 X 10.7 II 6.4 X 10.8 II
Beryllium 8.4x10.8 3.6x10.8 4.1 X 10.8 1.8x10.8 1.6xl0.8 6.9xl0.7 9.9x10.8 4.2x10-8 2.4 x 10" 1.0x10"
Chromium 3.8x10.3 II 3.8x10.3 II 1.5xl0.3 II 9.6x10.3 e 1.8xl0.2 e
Lead LOx 10.4 4.4 x 10" 3.1 X 10.6 1.4x10.6 5.1 x 10'. 2.2xl0'. 8.7xl0'. 3.6x10'. 2.6x10.4 1.2x10"
PCB's 2.5 x 10.4 1.9 X 10.4 2.6 X 10.6 1.1 X 10.4 5.8 X 10.4
a Assumas intaka 01 1.1 g/d dry waight
b Assumes intake 01 .88 g/d dry weight
C Assumes Intake 01 2.2 g/d dry weight
d Assumes intake 01 9.1 g/d dry waight
aNot considered carcinogenic by this route 01 axposure or pathway
'RID not aveileble to evaluata intake lor this pathway.
gSF not availabla to evaluate intake lor this pathway.
.. Indicates not applicable
e
Chromium
.~
-------
Table 7. Comparison of the Baseline Industrial Incremental Cancer Risk Assessment Results
using the Maximum Contaminant Concentrations and 95-percent UCL for the
Discolored Soil Site (UN-I 100-6), the Ephemeral Pool, and the Horn Rapids Landfill.
Subunit Pathway 95-percent UCL Maximum Concentration 95-percent Maximum Concentration
Pathway Totals Pathway Totals UCL Subunit Totals
Subunit
Totals
ICR ICR ICR ICR
Discolored Soli Site Soli Ingestion 2 x 10-6 3 X 10-6
(UN-1 100-6) Fugitive Dust Inhalation 2 x 10-7 4 X 10-7
Dermal Exposure 2 x 10-8 3 x 10-8
:-:::::;:::::::-:::::::i:::::::::::::::::::::::::::;:::,:,:;::::::::::;:::i::::::::::::::~;::::::::::::::;: """""'..............,........,..... =::il::::li::::i:::~:::i:::::~:::::::::i::::i';::::::::;:::::::::::::;:::1;::::::::::::::::::
1~iIIjj1f~jj~1i1i1i~jji~Ii~il~i1ti1i~jj~j1!~1jil~ii1j1i1iiiijji~ii1ir 2 x 10-6 3 X 10-6
Ephemeral Pool Soli Ingestion 9 x 10-8 3 X 10-6
Fugitive Dust Inhalation 3 x 10-7 8 X 10-7
Dermal Exposure 1 x 10-' 3 X 10-'
)1j1i~~~~ii~jiij~fj~j1~~lj~fjii~~~~~j~~~~1~~jIjijj~~ii1!1~~j~~~[fj1~j~jjj~~ililfj~~1j~1if~~j~j1~t1~1j11Ij ij~1ji~~~~1~1~j~~IIfI1~~f1~1t~~~~j~j1!1~11j1~~~~1~i~~tr ~~~1~~1~j~~1~~1~~~ii[ji1~1j1~~~~[jji~1i~~1[~t~1j1~1t~~~fj1~1j~~~jj~~~it~1~Ij~~j1:~ 2 x 10-' 6 X 10-'
Horn Rapids Soli Ingestion 2 x 10-6 6 X 10-'
Landfill
Fugitive Dust Inhalation 2 x 10-' 3 X 10-4
Dermal Exposure 3 x 10-6 8 x 10-6
-------
Table 8. Comparison of the Baseline Residential Scenario Risk Assessment Results
using the Maximum Contaminant Concentrations and 95-percent UCL for the
Discolored Soil Site (UN-l 100-6), the Ephemeral Pool, and the Horn Rapids Landfill.
Subunit Pathway 95.percent UCL Maximum Concentration 95.percent UCL Maximum Concentration
Pathway Totals Pathway Totals Subunit Totals Subunit Totals
HI" ICRb HI" ICRb HI" ICRb HI" ICRb
Discolored Soil So.illngestion 3.0 4 x 10.' 4.7 6 x 10.'
Site
(UN- 1100-61 Fugitive Dust Inhalation 5 x 10.7 7 x 10.7
Dermel Exposure 0.5 5 x 10.6 0.7 8 x 10.6
Garden Produce 15 2 x 10.3 18 2 X 10.3
18 2 x 10.3 23 3 x 10-3
Ephemeral Pool Soil Ingestion 0.1 2 x 10-c 0.2 5 x 10.'
Fugitive Dust Inhalation 6 x 10.7 2 X 10.8
Dermal Exposure 0.2 2 x 10.c 0.2 7 x 10.c
Garden Produce 2.2 8 x 1O.c 3.2 2 x 10.3
2.5 1 x 10.3 3.6 3 x 10.3
Horn Rapids Soil Ingestion 0.08 5 x 10-' 1 X 10.3
Landfill
Fugitiva Dust Inhaletion 4 x 10.6 7 x 10.'
Darmel Exposure 0.001 6 x 10-' 0.02 2 x 10.3
Garden Produce 0.3 2 x 10.3 3.6 4 x 10.3
Groundwater Ingestion 0.8 1 x 10.6 1 X 10.6
Inhalation of Volatiles 2 x 10.6 3 X 10.6
from Groundwater
1.2 3 x 10.3 5.6 8 x 10.3
8Hazard Indax
bUfetime Incremental Cancer Risk
UCl Upper Confidenca Limit
-------
The purpose of the toxicity assessment is to identify the potential adverse effects associated
with exposure to site-related substances and to estimate using numerical toxicity values, the
likelihood that these adverse effects may occur based on the extent of the exposure. The
toxicity assessment for the BISRA was conducted in accordance with RAGS and is discussed
in the HSBRAM. .
For carcinogenic chemicals, slope factors (SF's) are estimated using a conservative
mathematical model which estimates the relationship between experimental exposure (i.e.
doses) and the development of a cancer (i.e. response) that is derived from human or animal
studies. Since there is much uncertainty in the dose-response values generated using this
procedure, the upper 95 percent confidence limit of the slope of the dose-response curve is
normally used in deriving the slope factor.
For non-carcinogenic chemicals, the reference doses (RID) are used as benchmarks for toxic
endpoints of concern. RID's are derived from data obtained from studies in animals or
humans using modification and uncertainty factors that account for uncertainty in the
information used to derive the RID. Uncertainty factors are applied for extrapolation of the
no-observed-effects-Ievel (NOEL) in a study population to the RID used in the risk
assessment. A factor of 10 is usually applied to reflect the level of each of the sources of
uncertainty listed below:
.
Use of lowest observed effect level (LOEL) or other parameters that are less
conservative than NOEL;
.
Use of data from short-term exposure studies to extrapolate to long-term
exposure;
.
use of data from animal studies to predict human effects; and
.
use of data from homogeneous animal populations or healthy human
populations to predict effects in the general population.
A modifying factor may also be incorporated into the RID to reflect qualitative professional
judgements regarding scientific uncertainties not considered by the uncertainty factor, such as
the completeness of the data base and the number of animals in the study. Uncertainty
factors and modifying factors, as published by EPA in IRIS or HEAST, are presented in
Table 9.
For purposes of these baseline risk assessments, the chronic RID is utilized to evaluate
potential noncarcinogenic effects. The chronic RID is a daily exposure level that is not
likely to cause an appreciable lifetime risk of deleterious effects to the general population,
-------
Table 9. Summary of Carcinogenic Toxicity Information for the Contaminants
of Potential Concern at the 1100-EM-l Operable Unit.
Contaminant Weight of
Evidence Type of Cancer Oral SF Oral SF Inhalation SF Inhalation SF
Classification (mg/kg-d)"' (source) (mg/kg-d)" (source)
Arsenic A Skin, Lung 1.75' Surrogate 5.0 x 10' IRIS/HEAST
Beryllium B2 -- 4.3 IRIS 8.4 HEAST
Chromium VI A Lung NAb NA 4.1 x 10' IRIS/HEAST
Lead B2 -- ND NA NO NA
Nickel A Lung NAb NA 8.4 x 10" IRIS
BEHP B2 " 1.4 x 10.2 IRIS 1.4 x 10.2' Surrogate
Beta-HCH C -- 1.8 IRIS 1.8 IRIS
Chlordane 62 -- 1.3 IRIS 1.3 IRIS
DOT 62 -- 3.4 x 10.1 IRIS 3.4 x 10" IRIS
Heptachlor B2 -- 4.5 IRIS 4.5 IRIS
PCB's B2 " 7.7' IRIS 7.7. Surrogate
Tetrachloroethene B2",d .. 5.2 X 10.2 Reglon-10. 2 x 10.3 Reglon-10"
1,1,1-Trlchloroethane NA NA NA NA NA NA
Trichloroethene 62.,d .. 1.1 X 10.2 Reglon-10. 6.0 x 10.3 Reglon-10.
'Based on proposed arsenic unit risk of 5 x 10.6 pg/L
bNot considered carcinogenic by oral route 01 exposure
.As recommended by Superfund Technical Support Center, April 1992 (EPA.10)
Weight-of-evldence classification under evaluation
'Surrogate; assumed same as oral SF
-- Indicates not available; presented for Class A carcinogens only
NO = Not determined
NA = Not applicable
Sources: IRIS. Integrated Risk Information (Access: July, 1992),
HEAST . Health Effects Assessment Summary Tables,
-------
and sensitive subpopulations.
Table 10 summarizes the noncarcinogenic toxicity values for the COPC at the llOO-EM-1
Operable Units evaluated. Oral RID's have been published for all of the COPC except for
PCB's and trichloroethene. Confidence in these RID's is low or medium for all COPC
except nitrate. The confidence in the RID for nitrate is high because the values are derived
from human infant studies. An inhalation RID is published for only two of the COPC,
barium and l,l,l-trichloroethane. However, I, I, I-trichloroethane has only been detected in
soil gas and soil gas exposures are not evaluated.. The RID for barium is based on a 4-month
inhalation study in rats that resulted in fetotoxicity. Based on this reproductive study, an
interim RID is published in HEAST. It is under review and the RID is subject to change.
The noncarcinogenic effects for the COPC include a variety of effects such as altered blood
chemistry profiles for antimony, gastrointestinal irritation for copper, or increased. blood
pressure for barium. Liver effects, such as increased liver weight, lesions in the liver, or
changes in liver enzymes, are associated with thallium, BEHP, chlordane, DDT, heptachlor,
and tetrachloroethene. Skin effects are associated with arsenic. No critical effects are
identified for beryllium or chromium by the oral route. Nitrate is associated with changes
in the capacity of the blood system to transport oxygen.
4. Risk Characterization
The information from the exposure assessment and the toxicity assessment is used to
characterize the human health risks. The risk characterization presents quantitative and
qualitative descriptions of risk. The quantification of the noncarcinogenic risk and
carcinogenic risk is discussed below. Based on the results of the risk assessment using the
maximum contaminant concentrations, contaminants that are estimated to have a risk greater
than I x 10-6 were considered for evaluation using the 95-percent VCL values.
A. Quantification of Non-Carcinogenic Risk
Potential human health hazards associated with exposure to noncarcinogenic substances, or
carcinogenic substances with systemic toxicities other than cancer, are evaluated separately
from carcinogenic risks. The daily intake over a specified time period (e.g., lifetime or
some shorter time period) is compared to an RID for a similar time period (e.g., chronic
RID or subchronic RID) to determine a ratio called the hazard quotient (HQ). Estimates of
iJ1takes for both the BISRA and BRSRA are based on chronic exposures. The nature of the
contaminant sources and the low probability for sudden releases of contaminants from the
subunits preclude short-term fluctuations in contaminant concentrations that might produce
acute or subchronic effects.
The formula for estimation of the HQ is:
-------
Table 10.
Summary of Noncarcinogenic Toxicity Information for Contaminants of Potential Concern at the 1100-EM-l Operable Unit.
Contaminant ORAL INHALATION
Oral RId Oral Rfd Confidence Critical Effect Uncertainty Modifying Inhllation Inhalation RId Confidence Critica' Uncertainty ModifVing
(mglko.dav) (basis/source) Leyel Feetors Factor. Rfd (b.sll/aourceJ leyel effect Factor Flctor
(mglkg.dJ
Antim cny 4 X 10.' Wat.,nRIS low longeylly, blood 1,000 1 .. .. .. .. .. ..
glue.
Arsenic 3 X 10.' FoodnRIS medium hyperpigmentlti 3 1 .. .. .. .. .. ..
on kef ..osia
Barium 7 x 10-2 Wate,nRIS medium incr. blood prlSI 3 1 1 X 10.' HEAST .. .. 1.000 ..
Beryllium 6)( 10') Wate,nRIS -- none observed 100 1 .. .. .. .. .. ..
Chromium VI 6 x 10.' WaternRIS low none 600 1 .. .. .. .. .. ..
Coppe, 4 x 10.' EP A Region 10 .. GII"ltatlon .. .. .. .. -. .. .. ..
Leld ND .. .. .- .. .. ND .. ..
M -ng anese 1 x 10-1 IRIS .. .. .. .. 1.1" 10" .. .. .. .. ..
Nickol 2 x 10" FoodnRIS medium decrease body 300 1 .. .. .. .. .. ..
.. orQln weight
Thallium 8 x 10.' .nRIS .. SGOT Ind 3,000 .. .. .. .. .. .. ..
9 x 10.' lerum LDH leyel
Vanadium 7 x 10.' Wate,IHEAST .. none 100 .. .. .. .. .. .. ..
Zinc 2 x 10.1 HEAST .. anemia 10 .. .. .. .. .. .. ..
8EHP 2)( 10.' IRIS low liver weight 1000 1 .. .. .. .. .. ..
8a.a.HCH .. -. .. -- .. .. .. .. .. .. .. ..
Chlordane 8 x 10.' FoodnRIS low liver 1,000 1 .. .. .. .. .. ..
hypert,ophy in
mice
Hept.chlor 6" 10.' FoodnRIS low liver weight 300 1 .. .. .. .. .. ..
Tet'8chlorethene 1)( 10.' GlvagenRIS medium hePltotoxic In 1,000 1 .. .. .. .. .. ..
HEAST 1991 mIce, weight
Olin r.t
1.1.1. T ,ichloro.thlne 9 x 10.' O,allHEAST .. .. .. .. .. .. .. .. .. ..
Sou,c.s:
IRIS (Integrated Risk In'ormation System' Access: JuIV. 1992
HEAST IHealch Effects Assessment Summary Tables)
unlen otherwise indicated
NO "" Not determined
-------
HQ = Daily Intake
RfD
If the HQ exceeds unity, the possibility exists for systemic toxic effects. The HQ is not a
mathematical prediction of the severity or incidence of the effects, but rather is an indication
that effects may occur, especially in sensitive subpopulations. If the HQ is less than unity,
then the likelihood of adverse noncarcinogenic effects is small. The HQ for all contaminants
for a specific pathway or a scenario can be summed to provide a hazard index (HI) for that
pathway or scenario.
RID's are route specific. Currently, all of the RID's in IRIS are based on ingestion and
"inhalation; none have been based on dermal contact. Until more appropriate dose-response
factors are available, the oral RID's should be used to evaluate dermal exposures. The
uncertainty regarding these assumptions is discussed below in the uncertainty section.
B. Quantification of Carcinogenic Risk
For carcinogens, risks are estimated as the likelihood of an individual developing cancer over
a lifetime as a result of exposure to a potential carcinogen (i. e., incremental or excess ICR).
The equation for risk estimation is:
ICR = (Chronic Daily Intake) (Slope Factor)
This linear equation is only valid at low-risk levels (i.e., below estimated risks of 1 x 10-2),
and is an upperbound estimate of the upper 95th percent confidence limit of the slope of the
dose-response curve. Thus, one can be reasonably confident that the actual risk is likely to
be less than that predicted. Contaminant-specific ICR's are assumed to be additive so that
ICR's can be summed for pathways and contaminants to provide pathway, contaminant, or
subunit ICR's.
ICR's are presented for those contaminants known to be carcinogenic by a specific route of
exposure. For example, chromium is only carcinogenic by the exposure route of fugitive
dust inhalation. Consequently, an ICR is presented only for the exposure to chromium
through the inhalation of fugitive dust. All COPC that are classified as human carcinogens,
or probable human carcinogens, have published inhalation and oral Slope factors (SF's) with
two exceptions:
.
PCB's and BEHP do not have a published inhalation SF. For purposes of the
BISRA, the inhalation SF is assumed to be the same as the oral SF.
-------
.
No SF's are published for lead. Therefore, this contaminant of interest is not
evaluated for its potential contribution to the subunit total ICR. This may
result in an underestimation of the ICR for a subunit.
All of the toxicity factors in IRIS are based on ingestion and inhalation. None of the toxicity
factors have been based on dermal contact. Until more appropriate dose-response factors are
available, the oral SF's are generally used to evaluate dermal exposures.
The results of the risk characterization for carcinogenic effects are presented below by
subunit and summarized in Tables 11 and 12. These risk estimates are based on the
maximum detected contaminant concentrations. The 1 x 10-6 risk level is considered to be
the point of departure for determining remediation goals for alternatives when applicable or
re~evant and appropriate requirements (ARAR's) are not available or not sufficiently
protective.
C. Uncertainty Analysis
A human risk characterization examines the sources of the contaminant, its dispersion in the
environment and resulting exposure to humans, and the toxicological effects of such
exposure. The risks, both carcinogenic and noncarcinogenic, presented in this risk
assessment are conditional estimates given multiple assumptions about exposures, toxicities,
and other variables. This discussion focuses on the uncertainties surrounding the projected
risks and hazards due to uncertainty in these variables.
Uncertainty Associated with the Identification of COPe's. The soil sampling conducted
under the Phase I and Phase II RI's provides confidence that the COPC's at the llOO-EM-1
Operable Unit have been identified. Phase II sampling con finned sampling data from the
earlier remedial investigation activities except as noted below. Additional COPC's have been
identified and evaluated in the BISRA because of the more conservative risk-based screening
procedure used (e.g., ICR = 1 x 10-7 and HQ = 0.1), the availability of new toxicity
inforination (e.g., regarding beryllium), and additional sampling data and maximum
concentrations (e.g., regarding PCB's). However, overall results are consistent with the
results of the Phase I RI Report.
Uncertainty Associated with the Exposure Assessment. The exposure assessment is based
on a large number of assumptions regarding the physical setting of the l100-EM-l Operable
Unit, and the exposure conditions of the receptor population. For the purpose of the BISRA,
a conservative assumption is made that the COPC's being evaluated are readily accessible for
worker contact via ingestion, inhalation and dermal exposure pathways. Actual site
conditions, however, may substantially limit or preclude such exposures. In most cases, the
maximum concentrations detected are not uniformly distributed in the soil and may be several
feet below the surface. For the purpose of the BRSRA, a conservative assumption is made
that the COPC's being evaluated are readily accessible for receptor contact via ingestion,
inhalation, dermal, and garden produce pathways. Actual site conditions, however, may
-------
Subunit
UN-1100-6
Ephemeral Pool
Horn Rapids
Landfill
Table 11. Comparison of the Baseline Industrial Incremental Cancer Risk Assessment Results
using the Maximum Contaminant Concentrations and 95-percent UCL for
Discolored Soil Site (UN-l 100-6), the Ephemeral Pool, and the Horn Rapids Landfill.
95% UCL Maximum Concentration 95% UCL
Pathway Totals Pathway Totals Subunit
Totals
ICR ICR ICR
2 x 10.6 3 X 10.6
2 X 10.8 3 X 10.8
2 X 10.8 3 X 10.8
2 X 10.6
Pathway
Soli Ingestion
Fugitive Dust Inhalation
Dermal Exposure
8 X 10.8
3 X 10.6
::::::::::::\~~~;::::::::::I::\;1;::;;:::\~:\~\\~j:\j:\::\\:\:\j\\:\;:::\:!\=::\\\:\:\
6 X 10.6
3 X 10.6
2 X 10.6
5 X 10.6
Maximum Concentration
Subunit Totals
ICR
3 X 10.6
6 X 10.6
-------
Table 12. Comparison of the Baseline Residential Scenario Risk Assessment Results
using the Maximum Contaminant Concentrations and 95-percent VCL for
Discolored Soil Site (UN-l 100-6), the Ephemeral Pool, and the Horn Rapids Landfill.
Subunit Pathway 95% UCL Maximum Concentration 95% UCL Maximum Concentration
Pathway Totals Pathway Totals Subunit Totals Subunit Totals
HI8 ICRb HI8 ICRb HI8 ICRb HI8 ICRb
UN-" 00-6 Soil Ingestion 3.0 4 x 10-4 4.7 6 x 10.4
Fugitive Dust Inhalation 5 x 10.8 7 X 10.8
Dermal Exposure 0.5 5 x 10.6 0.7 8 x 10.6
Garden ProdUC8 15 2 x 10.3 18 2 x 10.3
18 2 x 10.3 23 3 x 10.3
Ephemeral Pool Soil Ingestion 0.1 2 x 10.4 0.2 5 x 10.4
Fugitive Dust Inhalation 6 x 10.8 2 x 10.7
Dermal Exposure 0.2 2 x 10-4 0.2 7 x 10.4
Garden Produce 2.2 8 x 10-4 3.2 2 x 10.3
::::i'::::::i::::::i~:!:::::::!:::::::i::i.:::::::!:::::::i!:i!::::::i:::::~::1~::i:::;::::ii:::::i:::i:;:~:::::::::::::~;i:::i:::::;:::!:::::::::::i:::::;:!:::i:::::::::::iiiiii:::~i:::::i::ilil:::::::i::::;:i:::::::::::i::i:::~::::i::!:!:!:I::~:::i!i:::!::!::::!:ii:!:i:!::!!li!!::!!:i!!::::::::i::::!
2.5
1 X 10.3
3.6
3 X 10.3
Horn Rapids Soillngastion 0.08 5 x 10-4 1 X 10.3
Landfill
Fugitive Dust Inhalation 4 x 10'. 6 X 10.6
Dermal Exposure 0.001 6 x 10.4 0.02 2 x 10.3
Garden Produce 0.3 2 x 10.3 3.6 4 x 10.3
Groundwater Ingestion 0.8 1 x 10.6 1 x 10.6
Inhalation of Volatiles 2 x 10.6 3 X 10.6
from Groundwater
:::::";i:.:;::::::i::::!:!::::!!::ii:::::::::::!:!:::!:::!:i;:I::::!:::::I::i:~:::::::::!::;:;:!:!:::::::!::::!::i:I:I:::!:::I::::!::!;:!:::;:::::::!;;::!!i:I!I::::i:ii:::i:I:I:i:II:11:1:::I:::I:::::1111::II::i:::::I:11i!::IIII::::;:I::::::i::li::I::I:I:11:1::I:::::!I::::!;:!:!:::::!:::I;:::::I;::;:::::::::::
1.2
3 X 10.3
5.6
7 X 10.3
8Hazard Index
bUfetime Incremental Cancer Risk
UCl Upper Confidence limit
-------
substantially limit or preclude such exposures. For example, residential use of the area in
,the foreseeable future is unlikely.
Other examples include exposure parameters (i. e., body weight, averaging time, contact rate,
exposure frequency, and exposure duration) are generally conservative default parameters
that represent reasonable maximum values as defined by EP A but may not reflect actual
exposure conditions. For example, the soil ingestion exposure pathway uses the assumption
that a resident or worker is present and ingesting dirt from the same site 350 days/year (d/yr)
for 30 years (residential scenario) or 146 d/yr for 20 years (industrial scenario). In addition,
the choice of intake parameters for all exposure pathways is governed by the specific land
use evaluated. Any land use change that would increase exposures by workers or indicate a
different receptor population would result in a need to reevaluate potential risks.
Absorption factors of contaminants from soil have been derived to evaluate the dermal
absorption pathway. Limited data are available on the absorption of chemicals from a soil
matrix. Therefore, the assessment of risks may be an overestimation or an underestimation
of the actual risk.
Uncertainty Associated with the Toxicity Assessment. Uncertainty is also associated with
the toxicity values and toxicity information available to assess potential adverse effects. This
uncertainty in the information and the lack of specific toxicity values for some COPC's
contribute to uncertainty in the toxicity assessment.
The RID's and SF's have multiple conservative calculations built into them that can
contribute to overestimation of actual risk (i.e., factors of 10 for up to four different levels
of uncertainty for RID's, and the use of a 95-percent upperbound confidence estimate derived
from the linearized multi-stage carcinogenic model for SF's). For example, Table 10
indicates that an uncertainty factor of 1,000 is used to calculate the RID's for chlordane and
tetrachloroethene. Table 9 shows that, while beryllium, BEHP, chlordane, and PCB's are
evaluated as human carcinogens, the available information indicates that there is inadequate
evidence of carcinogenicity in humans. The extrapolation of data from high-dose animal
studies to low-dose environmental human exposures may overestimate the risk in the human
population because of metabolic differences, repair mechanisms, or different susceptibilities.
Uncertainty in the Toxicity Assessment. Uncertainty is also present in the overall toxicity
assessment for several reasons. First, substances have been evaluated qualitatively when
there is a lack of toxicity values. Second, route specific toxicity values have been
extrapolated from one route to another (e.g., oral to dermal). Additionally, surrogate values
are used and potential synergistic or antagonistic interactions of substances have not been
evaluated. Conservative assumptions are provided regarding the species of the contaminant
present. For example, all chromium is assumed to be hexavalent chromium which is
carcinogenic. .
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Some contaminants, such as PCB's, only have toxicity values for carcinogenic effects (i.e.,
SF's), but do not have toxicity values for noncarcinogenic effects (i.e., RID's). These
contaminants are known to produce systemic toxic effects in addition to cancer. Without an
RID, quantitative evaluation of these other effects is limited. However, the potential to cause
cancer is usually the effect of most concern and is usually the effect that drives risks at most
sites. As indicated, surrogates are used to evaluate COPC's when numerical toxicity values
are not available. For all COPC's, the level of confidence that key effects have been
evaluated is high. The uncertainty surrounding dermal exposures and absorption from dermal
exposure is another significant source of uncertainty.
SUMMARY OF BASELINE INDUSTRIAL SCENARIO RISK ASSESSMENT
The baseline industrial scenario risk assessment (BISRA) was conducted according to
HSBRAM. Contaminants were determined by comparing maximum detected concentrations
of parameters to the UTL values for that parameter. The contaminants of potential concern
derived from this comparison were presented in Table 4. The contaminants were evaluated
in a two step process to minimize statistical analyses and allow health risk based comparison
of maximum value concentrations and 95-percent upper confidence limit (UCL)
concentrations. Maximum concentrations were used not only for preliminary risk based
screening but also for the initial risk based assessment calculations. If a health risk was
indicated using maximum concentration, then the 95-percent VCL concentration was used to
refine quantification of the health risk.
The maximum concentrations of contaminants of potential concern detected within each
subunit were evaluated for each subunit. Conservative assumptions were made with respect
to the contaminants present. For three subunits, VN-ll00-6 (Discolored Soil Site), the
Ephemeral Pool, and HRL, soil contaminants that were estimated to have an Incremental
Cancer Risk (ICR) greater than I x 10-6, based on the maximum detected contaminant
concentrations, were evaluated using a 95-percent VCL concentration.
The exposure pathways for the industrial were defined in the HSBRAM. These are
conservative default parameters for a generic industrial worker. The BISRA evaluated only
pathways associated with exposure to soils (i.e., soil ingestion, dennal exposure to soil, and
fugitive. dust inhalation). Potential exposures associated with groundwater and surfa~ water
were not evaluated in this BISRA because neither groundwater nor surface water is
withdrawn from the 1100 Area. Potable water is provided by the city of Richland. The air
inhalation pathway assumes exposure to windblown contaminants in dust directly from each
subunit. The EP A Fugitive Dust Model (FDM) was used to estimate concentrations of
airborne particulates at each site based on conservative estimation of soil and climatic
conditions. Chromium present in the soil at HRL was the only contaminant that may be
associated with risks greater than 1 x 10-6. However, all chromium was assumed to be
hexavalent chromium which is a conservative assumption and unlikely to be representative of
the true valence states present. Hexavalent chromium under aerobic conditions is reduced to
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trivalent chromium, an essential nutrient. Adverse effects have not been associated with the
trivalent chromium form.
Evaluation of the potential contaminants of concern using the maximum and 95-percent
UCL's identified the contaminants of concern for the individual subunits in the 1100-EM-1.
Contaminants of concern for individual subunits as determined in the BISRA are:
UN-UQO-6 (Discolored Soil Site) - BEHP
Ephemeral Pool - PCB's
HRL - Chromium - PCB's
A summary of the industrial scenario risk assessment based on the 95-percent UCL for UN-
1100-6 (Discolored Soil Site), Ephemeral Pool, and HRL was presented in Table 11. The
risk assessments for the Battery Acid Pit (1100-1), the Paint and Solvent Pit (1100-2), the
Antifreeze and Degreaser Pit (1100-3), and the Antifreeze Tank Site (ll0Q-4) demonstrated
that the Hazard Indices were all less than 1, and the incremetnal cancer risks were all less
than 1 x 10-6.
Chromium was identified as a contaminant of concern at HRL due to the fugitive dust
exposure pathway. This determination was made using maximum and 95-percent DCL soil
chromium concentrations taken at depths from 0 to 4.6 m (0-15 ft) in selected boreholes and
exploratory trenches. Using these values in risk based screening within the risk assessment
is appropriate. However, remedial actions to protect the ambient air quality from
contaminated fugitive dust migration should specifically apply to surface soils. Upon
reevaluating sample analyses from chromium in only the top 0.6 m (2 ft) of HRL, a mean
concentration for chromium in soils of 9.06 mg/kg with a 95-percent UCL of 9.76 mg/kg
was calculated. The Phase I RI reported chromium in background soils with a mean
concentration of 9.19 mg/kg and a 95-percent UTL of 12.9 mg/kg providing evidence that
chromium concentrations in the HRL surface soils are typical of the site. Using the 95-
percent DCL of 9.76 mg/kg to recalculate the incremental cancer risk of fugitive dust from
the HRL gives a risk of 2 x 10-7 under the industrial scenario. Therefore, chromium was
determined not to be a contaminant of concern and was not considered further.
SUMMARY OF BASELINE RESIDENTIAL SCENARIO RISK ASSESSMENT
The BRSRA was conducted to address uncertainty associated with future land use at the site.
Evaluation of the potential contaminants of concern using the maximum and 95-percent UCL
identified the contaminants of concern for the individual subunits in the lloo-EM-1.
Contaminants of concern for individual subunits as determined in the BRSRA are:
UN-l 100-6 (Discolored Soil Site) - BEHP, Chlordane
Ephemeral Pool - Chlordane, PCB's
HRL - Nitrate, PCB's, TCE
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A summary of the residential scenario risk assessment based on the 95-percent VCL for UN-
1100-6 (Discolored Soil Site), Ephemeral Pool, and HRL was presented in Table 12. The
risk assessments for the Battery Acid Pit (1100-1), the Paint and Solvent Pit (1100-2), the
Antifreeze and Degreaser Pit (1100-3), and the Antifreeze Tank Site (1100-4) demonstrated
that the Hazard Indices were all less than 1, and the incremetnal cancer risks were all less
than 1 x 1Q-6.
SUMMARY OF ECOLOGICAL RISK ASSESSMENT FOR THE llOO-EM-l
OPERABLE UNIT
The objective of the Ecological Risk Assessment is to provide an evaluation of the site
specific ecological risks. This Ecological Risk Assessment includes a problem defmition,
analysis, and risk characterization. Given the uncertainty in information available, it was not
practical to perform risk calculations for this evaluation. Ecological risk was estimated by
comparing exposure to the contaminant toxicity.
Using highly conservative assumptions and models, no uptake rates for the long-billed curlew
or the Swainson's hawk exceeded toxicity values. Contaminants with uptake rates that were
closest to toxicity values were zinc for the hawk and BEEP for the long-billed curlew, which
were approximately 10 and 20 times less than toxicity values, respectively. Therefore, it is
unlikely that contaminants of potential concern at lloo-EM-l would have an impact on these
birds that was distinguishable from background conditions. Even though there are significant
uncertainties in this assessment, there has been little evidence of ecological damage at the
site.
Problem DefInition. The problem definition involved identifying ecosystems potentially at
. risk, the stressor characteristics, ecological effects, and the selection of assessment and
measurement endpoints. Potentially sensitive habitats chosen for the lloo-EM-l site include
habitats known to be frequented by designated or proposed, endangered or threatened
species. In determining ecosystems potentially at risk at 1100 EM-I, only terrestrial
organisms were considered.
The dominant plant species within the 1100 Area are sagebrush-bitterbrush and cheatgrass.
The sand wort is designated a monitor species. Of the birds that may inhabit the 1100 Area,
the peregrine falcon and ferruginous hawk are endangered and threatened, respectively. The
Swainson's hawk, golden eagle, and prairie falcon are candidate species and the long-billed
curlew is a monitored species. No threatened or endangered species of mammals, reptiles,
or insects are known to inhabit the 1100 Area. However, the grasshopper mouse and
sagebrush vole are monitored, and the pocket gopher and striped whipsnake are candidate
specIes.
No toxicological studies were performed on species inhabiting lloo-EM-l for the Phase I or
Phase II RI. The toxicological effects on species exposed to the COPC are assumed to be
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those addressed in the derivation of parameters such as the No Observed Adverse Effect
Level (NOAEL). These parameters are used in the analysis and characterization sections.
Phase I field observations of the ecology of llQO-EM-l showed that there was no evidence of
adverse impacts from the COPC to the flora and fauna inhabiting any of the subunits, except
for the UN-llOO-6 (Discolored Soil Site). Except for a single clump of grass, there is no
vegetation growing in the depression of the UN-llQO-6 subunit (Discolored Soil Site). The
only evidence of ecological damage at the operable unit is this apparent lack of vegetative
growth at this subunit.
Assessment endpoints are the properties of habitats of potential concern that are used to
assess the state of an ecosystem. These endpoints "must be of ecological importance and of
direct management relevance...." When selecting assessment endpoints, it is preferable to
chose specific cases (such as reduced population size). However, with the lack of data
regarding the effects of contaminants at the site on organisms known to inhabit the site, this
was not possible. Therefore, adverse effects that generate the toxicological parameters
(NOAEL, etc.) on important species (i.e., the ferruginous hawk and peregrine falcon) were
considered assessment endpoints. It would be preferable to use effects on these species as
measurement endpoints, but data for the analog species (Swainson's hawk and long-billed
curlew) were more readily available.
Analysis. The analysis involved performing an exposure and toxicity assessment. This
involved first identifying the exposure pathways and secondly, calculating intake rates for the
receptor population (Swainson's hawk and long-billed curlew).
COPC uptake calculations for the Swainson's hawk and long-billed curlew were performed
according to Risk Assessment Guidance for Superfund. Table 13 lists maximum contaminant
concentrations and plant and small mammal uptake factors used in uptake calculations.
Similarly, the results of the uptake calculations are reported in Table 14. Appropriate
parameters were not always available, so conservative estimations, taken from previously
conducted studies, were made whenever necessary. Intake rates for the analog species
(Swainson's hawk and long-billed curlew) were compared to toxicological values in
Table 15. Values for birds were used whenever possible.
Risk Characterization. Given the uncertainty in information available, it was not practical
to perform risk calculations for this evaluation. Ecological risk was estimated by comparing
exposure to the contaminant toxicity.
None of the uptake rates in Table 13 exceed the toxicologic values in Table 15. For the
Swainson's hawk, uptake rates for zinc, BEHP, beta-Hexachlorocyclohexane (~-HCH),
1,1,1--trichloro-2, 2-bis(p-chlorophenyl)ethane (DDT), and PCB were between 10 and 80
times lower than the corresponding toxicity value. Uptake rates for copper, thallium, and
chlordane were between 2,000 and 20,000 times lower, and the remaining uptake rates were
more than 300,000 times below toxicity values. For the long-billed curlew, arsenic, barium,
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Table 13. Values used in Uptake Calculations
Maximum Plant Uptake Small Mammal
Contaminant Concentration, mg/kg Factor Uptake Factor
Antimony 15.6 O.Olb 0.002c
Arsenic 3.6 0.048 0.002C
Barium 1320 0.001 b O.OOlc
Beryllium . 1.3 0.438 O.OOlc
Chromium 17.1 0.28 0.0092C
Copper 58.6 0.38 0.158
Lead 482 0.008& O.OOO4c
Nickel 174 0.098 0.002C
Thallium 0.42 O.5b 0.02&
Vanadium 87.3 O.04b 0.0092c
Zinc 408 0.80- l.P
BEHP 24000 0.388 5.5-
Beta-HCH 0.094 0.38- 15.6-
Chlordane 1.86 0.05& 5.5-
DDT 2.0 0.118 5.7-
Heptachlor 0.065 0.028 14.2-
PCB's 100 0.388 5.58
. Values from EPA, 1986 mg/g tissue DW (mg/g soil DW)-l
bValues from Kabatus-Pendias and Pendias, 1985, mg/g tissue DW (mg/g soil DW)-1
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Table 14. Results of Uptake Calculations
Plant Insect Small Swainson's Long-Billed
Contaminant Uptake Uptake Mammal Hawk Uptake Curlew Uptake
mg/kg mg/kg Uptake Rate mg/kg-d Rate mg/kg-d
mg/kg
Antimony 0.16 0.16 1.2 x 1~ 1.6 X 10-8 1. 1 X 10-3
Arsenic 0.14 0.14 1.1 x 10-6 1.4 X 10-8 0.00079
Barium 1.32 1.32 5.2 x 1~ 6.2 X 10-8 0.0072
Beryllium 0.56 0.56 2.2 x 10-6 2.8 X 10-8 0.0031
Chromium 3.42 3.42 1.2 x 10-4 1.5 X 10-6 0.019
Copper 17.6 17.6 2.6 0.043 0.096
Lead 3.85 3.85 6.0 x 10-6 7.4 X 10-8 0.021
Nickel 15.7 15.7 1.2 x 10-4 1.6 X 10-6 0.086
Thallium 0.21 0.21 4.2 x 10-3 5.2 x 10-5 0.0011
Vanadium 3.5 3.5 1.3 x 10-4 1.5 x 10-6 0.019
Zinc 326 326 360 4.4 1.8
BEHP 9100 9100 50000 0.12 1.0
Beta-HCH 0.035 0.035 0.56 0.0069 2.0 x 10-4
Chlordane 0.093 0.093 0.51 1.3 x 10-6 1.0 x 10-5
DDT 0.22 0.22 1.3 0.015 0.0012
Heptachlor 0.0013 0.0013 0.018 4.4 x 10-8 1.4 X 10-7
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Table 15. Toxicological Values
Contaminant Toxicity. Toxicity Organism Comments
Parameter
Antimony 0.35 mglkg bw/d LOAEL Rat Chronic Oral
Arsenic 0.014 mg/kg/d LOAEL Human Chronic Oral
Barium 0.21 mglkg/d NOAEL Human Chronic drinking
Beryllium 0.54 mglkg bw/d NOAEL Rat Chronic Oral
Chromium 2.4 mglkg bw/d NOAEL Rat 1 year drinking
Copper 152 mg/kg TDLo Rat Chronic Oral
Lead 4.3 mg/kg/d LOAEL Hawk Subchronic Oral
Nickel 5 mglkg/d NOAEL Rat Chronic Oral
Thallium 0.7 mg/kg/d LOAEL Rat Chronic Oral
Vanadium 0.89 mglkg/d NOAEL Rat Chronic Oral
Zinc 96 mglkg/d NOAEL Mouse Drinking water
BEHP 19 mglkg bw/d LOAEL Guinea Pig Chronic Oral
Beta-HCH 0.33 mglkg/d NOAEL Rat Subchronic Oral
Chlordane 0.055 mg/kg/day NOEL Rat 30 mo Oral
DDT 0.49 mg/kg/d NOAEL Hawk Lifetime dosing
Heptachlor 0.15 mg/kg/day NOEL Rat 2-year Oral
PCB's 325 mglkg TDLo Mammals Subchronic Oral
.Values from IRIS
LOAEL = Lowest Observed Adverse Effect Level
NOAEL = No Observed Adverse Effect Level
TDLo = Toxic Dose Low
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nickel, vanadium, zinc, and BEHP had uptake rates 20 to 100 times less than toxicity values.
The other contaminants were more than 100 times less than toxicity values.
Uncertainty Analysis. There were many sources of uncertainty in the exposure assessment
and risk characterization for the ecological evaluation of l100-EM-l. All information
regarding the presence and beh~vior of species at the site, the exposure to contaminants, and
toxicity of contaminants was estimated and extrapolated from information available from
previous studies. Limited ecological data were taken from the site, therefore, the most
conservative and simple models were used to determine the ecological impact. Thus, the
exposure assessment represents the worst case scenario and the comparison of toxicity to
exposure was highly conservative.
Qualitative Risk Assessment for llOO-EM-2, llOO-EM-3 and
llOO-IU-1
A qualitative evaluation of overall potential risk from the 11DO-EM-2, l1DO-EM-3, and
l1oo-IU-l operable units was made by comparing possible waste site contaminant levels with
existing State and Federal health-based guidelines. The identification of potential waste types
for the 11oo-EM-2, l1oo-EM-3, and llOO-IU-l Operable Units is based upon historical
information about typical chemicals and materials that were used at the sites collected from
the WIDS, previous site investigations, and site reconnaissance activities. The COPC's for
each operable unit and a comparison to risk-based cleanup levels is presented below.
llOO-EM-2 Area
The potential contaminants of concern for the lloo-EM-2 Area are chlordane; 1,1,1-
trichloroethane (TCA) (700 Area UST waste solvent tank); and polychlorinated biphenyls
(PCB's) (1100 Area bus shop), s~ Table 16. .
Table 16. Potential Contaminants for the llOO-EM-2 Operable Unit
.WastenManagement'UIlir.. ...
...... '..' .. .".".':..',' .... ,..".:.. .:.:.:.:.:.:.'"", ...
700 Area UST Waste Solvent Tank
.PotentialCon~nant
TCA
Chlordane
PCB's
1100 Area Bus Shop
llOO-EM-3 Area
In the llOO-EM-3 Area, the potential contaminants include nitrates (1234 storage yard), lead
(3000 Area Jones Yard HWSA), carbon tetrachloride (CCl4) (1262 solvent tanks), and PCB's
(1262 transformer pad), see Table 17.
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Table 17. Potential Contaminants for the llOO-EM-3 Operable Unit
i~9~#.P~,G91)~~ri
NItrates
CCl4
PCB's
llOO-IU-1 Area (NIKE Missile Site)
Studies of NIKE missile sites for DOE by IT Corporation revealed that releases fall into four
general categories: incidental, accidental, intentional, and unanticipated. Incidental releases
consisted of minor release accompanying normal site operations. Accidental releases
occurred due to fuel spillage while fIlling UST's, and leakage of hydraulic fluid from
missiles, launchers, and elevators. Intentional releases involved the dumping of
unsymmetrical dimethylhydrazine (UDMH), waste solvents, and oils. Unanticipated releases
from transformers containing PCB's resulted from vandalism or negligence, and asbestos
released during the demolition of buildings. .
Typical chemicals used at NIKE sites include aniline, petroleum distillates, chlorinated
solvents such as CCI4, trichloroethene, trichloroethane, and tetrachloroethene, alcohols,
inhibited red fuming nitric acid, UDMH, phosphoric acid, alodine powder, chromium oxides,
acetone, paints containing chromium and lead, tricresyl phosphate, ethylene glycol,
pesticides, herbicides, PCB's (transformer oil), and hydraulic fluid (see Table 18).
In place of quantitative human health and ecological risk assessments, a qualitative evaluation
was made by presenting federal and state risk-based cleanup goals and advisories for known
or potential contaminants. Table 19 presents a baseline cleanup levels for protection of
human health. These values will be used to establish cleanup goals for these operable units.
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Table 18. Potential Contaminants for the llOO-IU-l Operable Unit
'," ',.'.'.' ,:::{yi Ci5.t,~MAA~gep.e~~:p;piP\...,..... ..,. ',',": ...'''' gQ!epn~:g9pr~~!9~(:t:: ....
.......
MIsslle Mamtenance & Assembly Area PCB s
Transformer Pad
Antl-Alfcnift Artillery Unexploded Ordnance
~issile Assemoly -Area Petroleum lJIstiJlates
Chlormated Solvents
Alcohols
MIsslle Fuehng and Warheadmg Area Dlmethylhydrazme (UDMH)
Inhibited red fummg mtrlc acid
(IRFNA)
Aniline
Furfuryl Alcohol
Ethylene oxide
Hydrocarbons such as jP-4 fuel
Missile Maintenance and Testing Phosphoric Acid
ATodme powder
Chromium trioxide
Sodium dichromate
Petroleum distillates
CCl4
Tnchloroethene
Trichloroethane
Tetrachloroethene
Alcohol
Acetone
Pamts contammg -Cr and Pb
Missile hydraulic tluid
Tncresyl Phosphate
General Launcher and Magazme Hydrarilicfluid
Maintenance
Paints
Solvents
Control Center Operations Maintenance Solvents used for cleaning electrical
parts
Ethylene glycol
Vehicle Mamtenance Petroleum, olls and lubricants
-FaCll1ty Mamtenance Lead pamts
Pesticides and herbicides
Utilities Transformers (PCB's), above and below
ground storage tanks used for gasoline
or fuel oil, and hydraulic fluid
Deactivation Solvents, fuels, paints, asbestos-
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Table 19. Potential Contaminant and Risk-Based Concentrations for llOO-EM-2, llOO-EM-3, and llOO-IU-l Soils
(mg/kg)
EP A Risk Based Concentrations MTCA A MTCA B MTCA C
Contaminant 10.6 10.4 HQ = 1 Carcinogen Non-carcinogen Carcinogen Non-carcinogen
1, I , I-Trichloroethane NA NA 20,000 20 - 7200 - 28,800
PCBs 0.08 8 NA 1.0 0.13 - 5.19 -
Carbon Tetrachloride 5 500 200 - 7.69 56 308 224
Aniline - - - - 175 - 7020 -
Furfuryl Alcohol - - . - - 240 - 960
Dimethylhydrazine - - . - 0.000714 - 0.0286 -
Acetone NA NA 30,000 - - 8000 - 32,000
Chromium Trioxide NA NA - - - - - 1600
Cr Paints NA NA - - - - - 1600
Sodium Dichromate NA NA - - - - - 1600
Trichloroethylene (TCE) 60 6000 NA 0.5 - - 3640 -
Benzene 20 2000 NA 0.5 34.5 - 1380 -
Toluene NA NA 50,000 40 - 16,000 - 64,000
Ethylbenzene NA NA 30,000 20 - 8000 - 32,000
Xylenes NA NA 500,000 20 - 160,000 - 640,000
Lead - - - 250 - - - -
Tetrachloroethene (PCE) - - - 0.5 - - - -
TPH (gasoline) - - - 100 - - - -
TPH (diesel) - - - 200 - - - -
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YD. REMEDIAL ACTION OBJECTIVES
Remedial Action Objectives (RAO's) are site specific goals that define the extent of cleanup
necessary to achieve the specified level of remediation at the site. The RAO's include
preliminary remediation goals derived from ARAR's, the points of compliance, and the
restoration timeframe for the remedial action. These goals are formulated to meet the overall
goal of CERCLA, which is to provide protection to overall human health and the
environment.
Contaminants of potential concern were identified based on a statistical and risk-based
screening process in site-affected media. The potential for adverse effects to human health
and the environment were initially identified in the Phase I RI report, and were further
evaluated in the BISRA and the BRSRA. Findings of these assessments are summarized in
the previous section. There are no contaminants that pose risks to ecological receptors.
Land Use. A key component in the identification of RAO' s is the determination of current
and potential future land use at the site. The current use and long range planning by the
city, county, and Hanford Site planners show the llOO-EM-l, EM-2 and EM-3 areas as
light industrial. The 11DO-IU-1 is entirely within the Arid Lands Ecological (ALE) Reserve.
Area planners expect that the current land use patterns will remain unchanged as long as the
Hanford Site exists. If control of the site is relinquished by the Government, land use in the
vicinity of the 1100 Area would be expected to remain unchanged due to the presence of
established commercial and industrial facilities that could be readily utilized by the private
sector. The ALE is expected to remain a wildlife management area for the foreseeable
future. These long range land use plans are not predictors of long-term land use (beyond 20
to 30 years) and should not be used as predictors of land use beyond reasonable lengths of
time, nor for land use changes resulting from longer term events.
The Hanford Future Site Users Working Group (the Working Group) was convened in April
of 1992 to develop recommendations concerning the potential use of lands after cleanup.
These recommendations are to be used as input into the Hanford Remedial Actions
Environmental Impact Statement (HRA-EIS) which is not expected to be published until 1995
or later. The Working Group issued their report in December 1992 and proposed that the
cleanup options at the 1100 Area be based on eventual unrestricted land use.
Factors that were considered in conjunction with the Working Group proposals include: (1)
that contaminated sites which would exist indefmitely (beyond any reasonable time for
assured institutional control) would be cleaned up for standards of unrestricted use where
practicable, and (2) that institutional controls (such as land and groundwater restrictions) be
implemented for sites associated with low risks where it can be shown that the contaminant
would degrade or attenuate within a reasonable period of time or, for sites where
contaminants would remain in place above unrestricted use cleanup goals, where it can be
shown that meeting the more stringent cleanup goal is not practicable. For this the 1100
Area, a reasonable period of time was identified by the Working Group as "as soon as
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possible (by 2018)". This time frame coincides with the TP A date for completion of cleanup
actions. This time frame also approximates the upper limit of reliability on long range land
use plans which have been used by DOE to determine the near-term site use.
Chemicals and Media of Concern. Risks from soil and groundwater contaminants of
concern were identified at levels that exceed the EP A risk threshold and may, therefore, pose
a potential threat to human health. The NCP requires that the overall incremental cancer risk
(ICR) at a site not exceed the range of 1 x l~ to 1 x 104. The State of Washington's
Model Toxics Control Act (MTCA) is more stringent and requires that this risk not exceed
1 x 10-6 to I x 10.5. For systemic toxicants or noncarcinogenic contaminants, acceptable
exposure levels shall represent levels to which the human population may be exposed witpout
adverse effect during a lifetime or part of a lifetime. This is represented by a hazard
quotient (HQ). For sites in the state of Washington where the cumulative carcinogenic site
risk to an individual based on reasonable maximum exposure for both current and future land
use is less than I x 10-5, and the noncarcinogenic HQ is less than 1, action generally is not
warranted unless there are adverse environmental impacts. However, if MCL's or nonzero
MCLG's are exceeded, action generally is warranted. Risks associated with 1100 Area
contaminants are summarized in Table 20.
Friable asbestos was found to be dispersed throughout HRL. The risk assessment did not
evaluate the risks associated with this contaminant because there are no published reference
doses or carcinogenic potency factors for asbestos. However, releases of friable asbestos in
fugitive dust does pose health risks to onsite workers.
The Phase n RI has confirmed the presence of groundwater contaminants at the site. .These
contaminants do not present any risk to human health under the current and future industrial
land use scenarios for the site because: (1) downgradient users are supplied by Richland's
water distribution system, and (2) the Phase I and n RI determined that the North Richland
well field is not impacted by the HRL contaminant plume and is not at risk. The
uncontrolled land use future uncertainty assessment using residential exposure indicates a
higher risk than the industrial scenario. However, that risk (3 x 10.5) is within the acceptable
risk range established by the NCP but is higher than that prescribed by MTCA.
TCE in groundwater was calculated to have an ICR of 3 x 10.5 for the uncertainty risk
assessment. Generally, where groundwater is a potential source of drinking water, clean up
requirements are set at levels which reduce the ICR to 1 x IQ-6 or to MCL's. Because of the
uncertain use of the aquifer as a potential source of drinking water in the long-term future,
TCE was identified as a contaminant of concern. The hazard quotient (HQ) associated with
nitrate in the groundwater for the uncertainty risk assessment was calculated to be 0.8.
Typically, a contaminant of concern has a HQ of 1 or greater. However, nitrate is present at
levels above MCL's making it a contaminant of concern to be monitored.
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a ,
TABLE 20. COMPARISON OF CONTAMINANT HAZARD QUOTIENTS (HQ)
AND INCREMENTAL CANCER RISKS (ICR)
ICR Based on BISRA ICR Based on BRSRA
Operable Subunit Contaminant Max Cone 95-pereent UCL Max Cone 95-percent UCL
HQ ICR HQ ICR HQ ICR HQ ICR
UN-I100-6 BEHP 0.4 3 x 10'5 0.3 2 x 10,5 21 3 x 10,3 16 2 x 10.3
Chlordane 0.02 4 x 10-7 0.01 4 x 10,7 2 8 x 10-5 2 7 x 10'5
Ephemeral Pool Chlordcine 0.03 6 x 10,7 0.02. 4 x 10,7 3.6 1 x 10-4 3 8 x 10,5
PCB's -- 6 x 10-5 -- 2 x 10,5 -- 3 X 10'3 -- 1 X 10'3
HRL Arsenic 0.006 1 x 10-6 0.001 2 x 10.7 0.1 2 x 10,5 0.03 4 x 10,6
Beryllium 0.00007 5 x 10-7 -- -- 0.006 5 x 10-5 0.002 2 x 10-5
Chromium 0.07 3 x 10-4 0.005 2 x 10'5 4.5 6 x 10-4 0.4 4 x 10,5
Lead' -- -- -- -- -- -- ' -- -- 1
PCB's -- 1 x 10-4 -- 5 x 10,5 -- 7 X 10-3 -- 3 X 10-3
TCE2 -- -- -- -- -- 4 x 10,5 -- 3 x 10.5
Nitrate2 -- -- -- -- 1 -- 0.8 --
I Lead was evaluated using EPA's Uptake Biokinetic (UBK) Model and was determined not to be present at levels which would cause adverse human
health effects.
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Soil RAO's. RAD's have been identified for the contaminated near surface and subsurface
soils at the Discolored Soil Site, the Ephemeral Pool, and HRL based on detected
concentrations of chemicals of concern exceeding ARAR's. Because there were no risks
from the Battery Acid Pit (1100-1), the Paint and Solvent Pit (1100-2), the Antifreeze and
Degreaser Pit (1100-3), and the Antifreeze Tank Site (1100-4), no action is necessary. All
RAD's shall minimize exposure to contaminated soils during remediation. These specific
operable unit RAD's are:
. Discolored Soil Site (UN-llOO-6)
a. Prevent the ingestion of and dermal contact with soils having BEHP
concentrations greater than the MTCA B cleanup level of 71 mg/kg.
b. For remedial actions that leave any contaminant in place above MTCA B
levels, provide adequate institutional controls to monitor the site after
remediation and to prevent potential future receptor exposure to contaminants.
. Ephemeral Pool
a. Prevent the ingestion of and dermal contact with soils having PCB
concentrations greater than the MTCA A cleanup level of 1 mg/kg.
b. For remedial actions that leave any contaminant in place above MTCA A
levels, provide adequate institutional controls to monitor the site after
remediation and to prevent potential future receptor exposure to contaminants.
. Horn Rapids Landiill
a. Prevent soil ingestion of and dermal contact with soils having PCB's at
concentrations greater than the MTCA C cleanup level of 5.2 mg/kg.
b. Prevent inhalation of fugitive dust from soils that may contain asbestos fibers.
c. For remedial actions that leave any contaminant in place above MTCA C
levels, provide adequate institutional controls to monitor the site after
remediation and to prevent future receptor exposure to contaminants.
Groundwater RAO's. For the contaminated groundwater, the following RAO's based on
chemical-specific ARAR's are identified.
a. Attain the SDW A MCL of 5 JLgll for TCE at the designated point of
compliance. The point of compliance is to be defined by EP A and Ecology.
Monitoring for compliance will be performed at the defined point.
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b. Protect environmental receptors in surface waters by reducing groundwater
contaminant concentrations in the plume to levels that are safe for biological
and human receptors that may be affected at the groundwater discharge point
to the Columbia River.
Residual Risks Post-Achievement of RAO's. Residual risks after meeting RAO's were
calculated based on the uncertain residential land use scenario for soils at the Discolored Soil
Site and the Ephemeral Pool, and the industrial land use scenario for soils at the HRL. The
uncertain re~identialland use scenario was used to determine residual risks for groundwater.
These risks are presented in Tables 21 and 22. Site risks from contaminated soils are
reduced from 2 x 10.3 to 2 x 1
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TABLE 21. RESIDUAL RISKS ASSOCIATED WITH SOIL RAO's
RAO Cone Soil Ingestion Fugitive Dust Dermal Exposure Contaminant Totals Subunit Totals
Operable Subunit Contaminant (mg/kg)
HQ Risk HQ Risk HQ Risk HQ Risk HQ Risk
UN-IIOO-6 BEHP 71' 0.013 2x I~ OM 2 x Ht9 0.002 2 x 10" 0.015 2x I~ 0.015 2xl~
Discolored Soil Site I
Ephemeral Pool' PCB's P -- I x W' -- 4 x W' .. 2 x 10' -- 3 x 10' -. 3 x 10'
HRL PCB's 5.2' -- 4x I~ -- 3 X 10' -. 4x 1~ - 8 x I~ -- 8x 1~
Maximum Site Risks 0.015 3 x 10'
I Residual risk associated with residential scenario.
2 RAO for subsurface soils based on MTCA Method B.
) RAO for subsurface soils based on MTCA Method A Table.
, RAO for subsurface soils based MTCA Method C.
TABLE 22. RESIDUAL RISKS ASSOCIATED WITH GROUNDWATER
RAO's (RESIDENTIAL SCENARIO)1
Operable Subunit Contaminant RAO Cone Water Ingestion Inhalation of Dermal Exposure Contaminant Totals Subunit Totals
. (mg/l) Household Release
HQ Risk HQ Risk HQ Risk HQ Risk HQ Risk
Site-wide TCE 0.005 - 6 x 10' -- 1 x 1~ .- -- - 2x 1~
Groundwater I
Nitrate 10 0.17 -- -- .. - - 0.17 ..
0.17 2x 1~
Site Totals .17 2xl~
I RAO's for groundwater are based on SDWA MCL's.
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VID. DESCRIPTION OF ALTERNATIVES
A. Soil Alternatives
1. Discolored Soil Site
Alternative DSS-O: No Action. Evaluation of this alternative is required under CERCLA;
it serves as a reference against which other alternatives can be compared. Under this
alternative, no action would be taken to remove, treat, or contain contamination at this site
and no institutional controls would be established to prevent exposure. There is no cost
associated with this alternative.
Alternative DSS-1: Onsite Bioremediation. A diked treatment area approximately 30.5 m
by 36.6 m (100 ft by 120 ft) would be constructed onsite and lined with an impervious
geomembrane. The soils contaminated with BEHP above 71 mg/kg, estimated to be a
maximum of 340 m3 (440 yd3), would be excavated and placed into the treatment area. A
sprinkler system would deliver a mixture of water, nutrients, and microorganisms,
specifically cultured for their ability to degrade BEHP, to the soils approximately twice a
week. The soils would be tilled after each application of this mixture to provide additional
mixing and aeration. Excess water would be collected and recycled. A bioreactor would be
required onsite to culture the microorganisms. It was assumed that bioremediation would be
conducted for 36 weeks a year with a suspension of operations during the colder winter
months, which inhibit bacterial growth and respiration. The entire remediation process was
assumed to take 2 years. After remediation, the soils would be placed back at the Discolored
Soil Site and the area would be regraded and covered with 15 cm (6 in) of topsoil. The total
estimated present worth cost for this alternative is $997,000 (includes capital and O&M
costs).
Alternative DSS-2: Onsite Incineration. Onsite incineration would be accomplished by
using a small mobile incinerator capable of processing approximately 4.5 metric tons (5-tons)
of contaminated soil per day. There would be approximately 770 metric tons (840 tons) of
soils contaminated with BEHP to be processed. Combustion off gases would be treated to
meet air quality standards for emissions through use of a secondary combustion chamber and
wet scrubbers. Ashes would be quenched with water and the quench water would be
recirculated. After incineration, the treated soil would be placed back at the operable subunit
and the area would be regraded and covered with 15 cm (6 in) of clean topsoil. Materials
would be excavated using standard equipment for earthwork. Confirmatory testing would be
conducted to ensure that all contaminated soils above cleanup levels are removed. A 30.5-m
(1oo-ft) graded square pad would be required to house the incinerator. The total estimated
present worth cost for this alternative is $1,491,000 (includes capital and O&M costs).
Alternative DSS-3: Offsite Incineration. Approximately 770 metric tons (840 tons) of
soils contaminated with BEHP would be excavated and shipped to an offsite incinerator.
DOT-licensed hazardous waste haulers would carry the contaminated soils in bulk truck loads
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to a RCRA licensed facility. After incineration, the ash would be disposed of in this
facility's ash disposal landfill. Post action sampling and analyses of remaining subunit soils
would be required to confinn the level of cleanup. After completion of the action, the site
would be regraded and covered with 15 cm (6 in) of clean random fill. The total estimated
present worth cost for this alternative is $2,131,000 (capital only, O&M costs are
negligible).
2. Ephemeral Pool Soil
Alternative EPS-O: No Action. Evaluation of this alternative is required under CERCLA;
it serves as a reference against which other alternatives can be compared. Under this
alternative, no action would be taken to remove, treat, or contain contamination at this site
and no institutional controls would be established to prevent exposure. There is no cost
associated with this alternative.
Alternative EPS-l: Offsite Disposal. Approximately 250 m3 (340 yd3) of soil contaminated
with PCB's above 1 mg/kg would be removed and disposed of. Front end loaders would be
used for excavation and hauling would be by Department of Transportation (DOT) approved
hazardous waste haulers. The contaminated material would be hauled in bulle Material
would be removed in phases with confirmatory testing conducted between each phase to
verify that RAO's are met. At the completion of the action, the site would be regraded and
covered with 15 cm (6 in) of clean random fill material. The total estimated present worth
cost for this alternative is $356,000 (capital only, O&M costs are negligible).
Alternative EPS-2: Onsite Incineration. Onsite incineration would be accomplished by
using a small mobile incinerator capable of processing approximately 4.5 metric tons (5-tons)
of contaminated soil per day. There would be approximately 450 metric tons (490 tons) of
soils contaminated with PCB's above I mg/kg to be processed. Combustion off gases would
be treated to meet air quality standards for emissions through use of a secondary combustion
chamber and wet scrubbers. Ashes would be quenched with water and the quench water
would be recirculated. After incineration, the treated soil would be placed back at the
operable subunit and the area would be regraded and covered with 15 cm (6 in) of clean
topsoil. Materials would be excavated using standard equipment for earthwork.
Confirmatory testing would be conducted to ensure that all contaminated soils above cleanup
levels are removed. A 30.5-m (loo-fO graded square pad would be required to house the
incinerator. The total estimated present worth cost for this alternative is $1,391,000
(includes capital and O&M costs).
Alternative EPS-3: Offsite Incineration. Approximately 450 metric tons (490 tons) of
soils contaminated with PCB's would be excavated and shipped to an offsite incinerator.
DOT-licensed hazardous waste haulers would carry the contaminated soils in bulk truck loads
to a RCRA licensed facility. After incineration, the ash would be disposed of in this
facility's ash disposal landfill. Confirmatory sampling and analyses of remaining soils would
be required to confirm the level of cleanup. After completion of the action, the site would
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be regraded and covered with 15 cm (6 in) of clean random fill. The total estimated present
worth cost for this alternative is $1,214,000 (capital only, O&M costs are negligible).
3. Horn Rapids Landf"ill
Alternative HRL-O: No Action. Evaluation of this alternative is required under CERCLA;
it serves as a reference against which other alternatives can be compared. Under this
alternative, no action would be taken to remove, treat, or contain contamination at this site
and no institutional controls would be established to prevent exposure. There is no cost
associated with this alternative.
Alternative HRL-l: Asbestos Cap. The first part of this alternative is removal and off-site
disposal at a TSCA-permitted landfill of the area of soil known to be contaminated with
PCB's above the MTCA C level of 5 mg/kg (approximately 226 m3). Next, the asbestos cap
would be constructed by placing 37,100 m3 (48,500 yd3) of clean random fill material over
the 10.1 hectare (25 acre) site which is the area actively used as the landfill. Forty-five cm
(18 in) of random fill material would be placed uniformly over the site following existing
contours; no effort would be made to direct surface runoff off of the cap area. Placement of
the first 15 cm (6 in) layer of this material would require the use of special construction
practices to limit the exposure of remedial workers to fugitive dust. An additional 15 cm (6
in) topsoil layer would then be placed and seeded to dryland grasses. Total cap thickness
would be 60 cm (2 ft). A notice will be placed on the deed to this property that identifies
this as an asbestos-containing landfill. The total estimated present worth cost of this
alternative is $2,634,000 (Capital $2,011,000 and O&M $41,000 for 30 years, discounted at
5%). The cost for removal and off-site disposal of the PCB-conataminated soil is $205,000.
Alternative 1IRL-2: Municipal Landfill Cap. The first part of this alternative is removal
and off-site disposal at a TSCA-permitted landfill of the area of soil known to be
contaminated with PCB's above 5 mg/kg (approximately 226 m3). Next, the municipal
landfill cap would be installed, consisting of a minimum of 15 cm (6 in) of topsoil over a
geomembrane. The cap would be placed over the 10.1 hectare (25 acre) area, which is the
extent of the actively used landfill. The cap would be designed to have a minimum 2-percent
drainage slope to facilitate surface runoff. Because of the width of the landfill, intermediate
drainage swales would be used to intercept this runoff. At these swales, perforated pipe
would be used for surface drainage collection and the intercepted runoff would be carried
past the extent of the cap into a drain field where it would be allowed to percolate through
the vadose zone. The construction of the cap would require approximately 86,500 m3
(113,000 yd3) of random fill material to be used in preparing an adequately sloped subgrade.
A geomembrane bedding layer would be placed on top of the random fill. Next, 87,900 m2
(105,000 yd3) of geomembrane would be placed and covered with 15 cm (6 in) of topsoil.
The capped area would be reseeded to establish a vegetative cover and 1.83 kIn (6000 ft) of
perimeter fence would be constructed to restrict access to the site. Appropriate warning
signs would be posted to inform the public that the area is a past landfill site that contains
asbestos material. The total estimated present worth cost of this alternative is $6,608,000
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(Capital $5,445,000 and O&M $41,000 for 30 years, discounted at 5%). The cost for
removal and off-site disposal of the PCB-conataminated soil is $205,000.
4. EM-2, EM-3, AND IV-I Soil and Debris
Alternative OSS-O: No Action. Evaluation of this alternative is required under CERCLA;
it serves as a reference against which other alternatives can be compared. Under this
alternative, no action would be taken to remove, treat, or contain contamination at these sites
and no institutional controls would be established to prevent exposure. There is no cost
associated with this alternative.
Alternative OSS-l: Offsite Disposal. Under this alternative, underground storage tanks,
pipes, sumps, and cisterns would be excavated, along with visibly stained or contaminated
soils. Field sampling would be conducted during excavation to ensure that all contaminated
soils are removed. All excavated materials would be stored onsite until they are transported
and disposed of in accordance with applicable State and Federal requirements. All excavated
areas would be back-filled with clean fill and revegetated to match surrounding topography.
The estimated volume to be disposed is approximately 6000 yd3. The estimated cost of this
alternative is $4,455,000.
Alternative OSS-2: Onsite Incineration. Under this alternative, underground storage
tanks, pipes, sumps, and cisterns would be excavated, along with visibly stained or
contaminated soils. Field sampling would be conducted during excavation to ensure that all
contaminated soils are removed. All excavated materials would be stored on site until they
are disposed of offsite or incinerated. Onsite incineration would be limited to contaminated
soils, sediments, and small debris. Larger items such as tanks, piping, and demolition debris
would be disposed of offsite. The incinerator residuals would be placed back into the
excavated areas and covered with clean fill. All excavated areas would be back-filled with
clean fill and revegetated to match surrounding topography. The estimated cost of this
alternative is $7,974,000.
B. Groundwater Alternatives
Alternative GW-O: No Action. Evaluation of this alternative is required under CERCLA;
it serves as a reference against which other alternatives can be compared. Under this
alternative, no action would be taken to treat or contain contaminated groundwater and no
institutional controls would be established to prevent exposure. There is no cost associated
with this alternative.
Alternative GW-l: Natural Attenuation, Monitor, Evaluate Need for Further Action.
Under this alternative, the groundwater contamination would be allowed to naturally
attenuate. Groundwater monitoring and modelling have indicated that the TCE plume is
expected to attenuate to levels below MCL's by the year 2017. Restrictions on the drilling
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of supply wells would be enforced during this period. Under this alternative, additional
wells would be installed and regularly monitored along George Washington Way as a point
of compliance. In the event that TCE concentrations exceed MCL's at the well sites, active
groundwater remediation such as extraction and treatment would be evaluated. The total
estimated present worth cost for this alternative is $1,059,000 (capital-$685,000; O&M-
$24,300 discounted at 5 % for 30 years).
Alternative GW-2A: Extraction and Treatment. TCE would be removed from
contaminated groundwater by pumping groundwater through an air stripper. Air emissions
from this process would contain low levels of TCE that are not expected to require additional
treatment. The treatment system would operate at 100 gallons per minute (gpm). TCE levels
in groundwater would be expected to reach MCL's by the year 2012. The total estimated
present worth cost for this alternative is $5,111,000 (capital-$1,536,000; O&M-$256,3oo
discounted at 5% for 17 years).
Alternative GW-3A: Extraction and Treatment. This is the same treatment process as
GW-2A. However, this system would operate at 300 gpm. TCE levels in groundwater
would be expected to reach MCL's by the year 2008. The total estimated present worth cost
for this alternative is $8,989,000 (capital-$3,557,000; O&M-$505,000 discounted at 5% for
13 years).
Alternative GW-2B: Extraction and Treatment. Extracted groundwater would be treated
for TCE removal by a system consisting of a multimedia fIlter and an ultraviolet
radiation/chemical oxidation treatment unit using ozone and hydrogen peroxide to destroy
TCE. In this process, TCE is chemically destroyed and converted to carbon dioxide and
water. The process would operate at 100 gpm and TCE levels in groundwater would be
expected to reach MCL's by the year 2012. The total estimated present worth cost for this
alternative is $5,714,000 (capital-$2,072,000; O&M-$262,000 discounted at 5% for
17 years).
Alternative GW-3B: Extraction and Treatment. This is the same treatment process as
GW-2B. However, this system would operate at 300 gpm. TCE levels in groundwater
would be expected to reach MCL's by the year 2008. The total estimated present worth cost
for this alternative is $9,970,000 (capital-$4,228,000; O&M-$538,000 discounted at 5% for
13 years).
IX. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section summarizes the relative performance of each of the alternatives with respect to
the nine criteria identifIed in the NCP. These criteria fall into three categories: The fust
two (Overall Protection of Human Health and the Environment and Compliance with
ARAR's) are considered threshold criteria and must be met. The next fIve are considered
balancing criteria and are used to compare technical and cost aspects of alternatives. The
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final two criteria (State and Community Acceptance) are considered modifying criteria.
Modifications to remedial actions may be made based upon state and local comments and
concerns. These were evaluated after all public comments were received.
A. Threshold Criteria
1. Overall Protection of Human Health and the Environment
Overall Protection of Human Health and the Environment addresses whether or not a remedy
provides adequate protection and describes how risks posed through each pathway are
eliminated, reduced, or controlled through treatment, engineering controls, or institutional
controls.
All of the alternatives, except the no action alternatives (DSS-O, EPS-o, HRL-O, OSS-O, and
GW-O) would provide some protection of human health and the environment. DSS-3 is
protective because it removes and treats the contaminated soils at the Discolored Soil Site.
Alternative EPS-l is protective because it removes and properly disposes of the contaminated
soils at the Ephemeral Pool. Exposure to asbestos (the principal threat) at the Landfill would
be prevented by providing an asbestos-landfill cap (Alternative HRL-l) to contain the soils
by preventing windblown dust. Alternative GW -1 prevents exposure to contaminated
groundwater while the contamination attenuates to levels that do not pose undue risks.
Alternative DSS-l would reduce the levels of BEHP, but it may not be completely successful
because the technology is unproven beyond laboratory-scale tests. Alternative DSS-2,
EPS-2, and EPS-3 would be fully protective of human health and the environment because
these alternatives would destroy the contaminants at the sites. Alternative HRL-2 would also
prevent exposure to asbestos. Groundwater Alternatives GW-2A, GW-2B, GW-3A, and
GW-3Bwould be protective by preventing exposure and would also utilize groundwater
extraction and treatment for some acceleration of cleanup.
Alternatives OSS-1 and OSS-2 would meet the remedial action objectives. For Alternative
OSS-I, protection of human health would be provided by reducing the risks through removal
and offsite disposal. Alternative OSS-2 would achieve protection through incineration.
2. Compliance with ARAR's
Compliance with ARAR's addresses whether a remedy will meet all of the applicable or
relevant and appropriate requirements (ARAR's) of other Federal and State environmental
laws and/or justifies a waiver.
Soil alternatives DSS-2, DSS-3, EPS-l, EPS-2, EPS-3, HRL-l, HRL-2, OSS-I, and OSS-2
can meet all identified ARAR's. - Alternative DSS-l may not be efficient enough to meet
cleanup levels without additional controls (e.g. institutional controls and/or capping). The
"No Action" alternatives do not comply with ARAr's. Groundwater alternatives GW-l,
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GW-2A, GW-2B, GW-3A, and GW-3B would achieve ARAR's, although the timeframes
vary from 16 years to 25 years.
B.. Primary Balancing Criteria
Because the "No Action" alternatives are not protective of human health and the environment
and do not comply with ARAR's, they are not considered further.
3. Long-Term Effectiveness and Pennanence
Long-Term Effectiveness and Permanence refers to the magnitude of residual risk and the
ability of a remedy to maintain reliable protection of human health and the environment over
time once cleanup goals have been met.
Alternatives DSS-2, DSS-3, EPS-2, EPS-3, and OSS-2 have the highest degrees of
effectiveness and permanence because they employ incineration to destroy the contaminants.
Alternative DSS-l would be permanent, but the technology is unproven beyond laboratory-
scale tests. Both HRL-l and HRL-2 will be effective for the life of the caps. The estimated
useful life of landfill caps is 30 to 50 years. In practice, the useful life of the asbestos cap
could be much longer depending on site conditions and use. Alternative OSS-1 has a
high degree of long-term permanence because contaminants are removed offsite to a
controlled facility. All of the groundwater alternatives would be expected to provide
long-term effectiveness once cleanup goals are attained. As noted above, the timeframes to
achieve cleanup goals vary.
4. Reduction of Toxicity, Mobility, or Volume through Treatment or Recycling
Reduction of Toxicity, Mobility, or Volume through treatment is the anticipated performance
of the treatment technologies that may be employed in a remedy.
Soil Alternatives DSS-2, DSS-3, EPS-2, EPS-3, and OSS-2 utilize treatment to reduce
contaminant volume, mobility, and toxicity. Alternative DSS-I also utilizes treatment, but as
previously described, the degree of reduction is unproven. Groundwater Alternatives
GW-2A, GW-2B, GW-3A, and GW-3B all employ technologies that would reduce mobility
and volume. Groundwater Alternatives GW-2B and GW-3B also reduce TCE toxicity by
destroying the TCE.
5. Short- Tel1D Effectiveness
'-'
Short-Term Effectiveness refers to the speed with which the remedy achieves protection, as
well as the remedy's potential to create adverse impacts on human health and the
environment during the construction and implementation period.
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All of the soil alternatives would create some level of short-term risk until the actions are
completed, however workers and nearby residents would be protected during site activities by
engineered and administrative controls. The actions described in soil alternatives DSS-2,
DSS-3, EPS-I, EPS-2, EPS-3, HRL-l, HRL-2, and OSS-1 could be completed within a 6 to
9 .month timeframe. Alternative DSS-l, due to the uncertainties associated with
bioremediation, and Alternative HRL-2, which requires specialized equipment to install the
synthetic liner, would take longer to complete. Alternative OSS-2 would take 1 to 2 years to
implement. Alternatives GW-3A and GW-3B would achieve cleanup goals in the shortest
timeframe (approximately 16 years). Emissions from the air stripper used in GW-2A and
GW-3A are relatively low and should not require additional treatment. Neither the active
nor passive alternatives pose any undue risks for implementation.
~
6. Implementability
Implementability is the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the solution.
All of the soil alternatives can be implemented, although with varying degrees of difficulty.
Mobilizing an onsite incinerator (required for DSS-2, EPS-2, and OSS-2) poses additional
difficulties. The bioremediation option (DSS-1) would require treatability testing prior to
implementation. All groundwater alternatives are readily implementable.
7. Cost
Cost includes capital and operation and maintenance costs. The estimated costs are present
worth costs (capital costs plus annual costs over the life of the project, with a 5% discount
rate).
The estimated costs of the Discolored Soil Site alternatives range from $997,000 to
$2,131,000. .
The estimated costs of the Ephemeral Pool alternatives range from $356,000 to $1,391,000.
The estimated costs of the Horn Rapids Landfill alternatives range from $2,839,000 to
$6,813,000.
Alternative 055-1, Offsite Disposal, is estimated to cost $4,455,000, while Alternative
OSS-2, On site Incineration, is estimated to cost $7,974,000.
The estimated costs of the groundwater alternatives range from $1,059,000 to $9,970,000.
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C. Modifying Criteria
8. State Acceptance
~
State Acceptance indicates whether, based on its review of the Final RIfFS Report and
Proposed Plan, the State concurs with, opposes, or has no comment on the preferred
alternative.
The Washington State Department of Ecology concurs with the selection of the final remedial
alternative described in this ROD. Ecology has been involved with the development and
review of the Remedial Investigation, Feasibility Study, Proposed Plan, and Record of
Decision. Ecology comments have resulted in significant changes to these documents and
has been integrally involved in determining which cleanup standards apply under MTCA.
9. Community Acceptance
Community Acceptance refers to the public's support for the preferred remedial alternative
and is assessed following a review of the public comments received on the Final RIfFS
Report and the Proposed Plan.
On June 30, 1993, a public meeting was held to discuss the Proposed Plan for the 1100
Area. The results of the public meeting and the public comment period indicates acceptance
of the preferred remedial alternative, with some exceptions, one of which resulted in a minor
deviation from the proposed plan. Community response to the remedial alternatives is
presented in the responsiveness summary, which addresses questions and comments received
during the public comment period.
X. SELECTED REMEDY
The selected remedy for the 1100 Area NPL Site includes Offsite Incineration of BEHP-
Contaminated Soils at the Discolored Soil Site (Alternative DSS-3), Offsite Disposal of PCB-
Contaminated Soils at the Ephemeral Pool (Alternative EPS-l), an Asbestos Cap at the HRL
(Alternative HRL-l), and Offsite Disposal of Contaminated Soil and Debris from the
llOO-EM-2, llOO-EM-3, and llOO-IU-l Operable Units (Alternative OSS-I). The selected
remedy also includes Natural Attenuation and Groundwater Monitoring for Compliance with
MCL's (Alternative GW-l). Table 23 summarizes the risk reduction of the selected remedy.
v
Of the nine criteria described above, the criteria which weighed heavily in the decision are
Long-Term Effectiveness, Implementability, and Cost. The components of the selected
remedy achieve the best balance of these three criteria. Among the DSS alternatives,
Alternative DSS-3 provides for the highest level of long-term effectiveness and
implementability, but it does have the highest cost. Alternative EPS-l has a lesser degree of
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Table 23. Summary of the Selected Alternative
Current Risk Selected Remedy Risk After Remediation Cost
Discolored Soil Site 2 x 10-3 Offsite Incineration 2 x 10-6 $2,131,000
Ephemeral Pool 1 x 10-3 Offsite Disposal 3 x 10-5 $356,000
Horn Rapids Landfill 7 x 10-5 Asbestos Landfill Closure 8 x 10-6 $2,839,000
Groundwater 3 x 10-5 Natural Attenuation with 2 x 10-6 $1,059,000
continued monitoring
Contaminated Soil and Debris > 10-58 Offsite Disposal < 10.58 $4,455,000
from EM-2, EM-3, and IU-l .
8 Assessment is qualitative
c
o '
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long-term effectiveness than the other EPS alternatives, but it is very implementable and has
the lowest cost. The asbestos cap for the Horn Rapids Landfill (Alternative HRL-1) has the
better long-term effectiveness, implementability, and the lowest cost of the HRL alternatives.
Alternative OSS-l has the lowest cost and better implementability, although the long-term
effectiveness may be slightly less. The groundwater alternatives are approximately equal in
terms of long-term effectiveness and implementability, but GW-1 has a significantly lower
cost.
()
The total estimated costs of the remedy are $10,840,000. The preliminary design
considerations described in this ROD are for cost estimating and are subject to change based
on the final remedial design and construction practices.
A. orfsite Incineration BEHP-Contaminated Soils
Soil from the Discolored Soil Site which is contaminated with BEHP above the MTCA
cleanup level of 71 mg/kg will be removed and transported to a permitted, offsite
incinerator. After incineration, the residuals will be disposed of in that facility's ash disposal
landfill. This will prevent exposure to soils contaminated with BEHP above the cleanup
level. The approximate volume to be excavated is 100 cubic meters (130 cubic yards).
During the excavation, samples will be taken to monitor progress. Confirmation samples
will also be taken to verify that cleanup levels have been met. The site will be re-graded.
B. orfsite Disposal of PCB-Contaminated Soils
Ephemeral Pool Soils contaminated with PCB's above the MTCA cleanup level of 1 mg/kg
will be removed and properly disposed of at a TSCA-permitted, offsite landfill. This will
prevent exposure to soil containing PCB's above the cleanup level. The estimated volume is
125 cubic meters (165 cubic yards). Confirmatory sampling will be performed to verify that
the cleanup level is met.
C. Asbestos Cap
The Horn Rapids Landfill will be closed as an Asbestos Landfill in accordance with the
Asbestos NESHAP (40 CFR 61.151). This will prevent exposure to asbestos-containing
dusts. Prior to installation of the cap, a localized area of soil that is contaminated with
PCB's will be removed. This area is centered around a vadose zone borehole in the Horn
Rapids Landf111 (borehole HRL-4). Approximately 226 cubic meters (296 cubic yards) of
soil contaminated with PCB's above 5 mg/kg will be removed and transported to a TSCA-
permitted, offsite landfill. Both field monitoring and confirmatory sampling will be
performed to ensure that the 5 mg/kg level is met.
G
D. Offsite Disposal of Contaminated Soil and Debris
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Soil and debris from the sites in the 1100-EM-2, lIOO-EM-3, and ll00-IU-l Operable Units
(from Table 5-1 from Volume IV of the RIfFS Report) which are contaminated above the
levels in Table 19 will be removed and disposed in a permitted offsite landfill. Field
monitoring will be performed during excavation and then samples will be taken and analyzed
to confirm that the cleanup levels have been met.
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G
;)
The selected remedy protects human health and the environment through soil and
groundwater actions. Implementation of this remedial action will not pose unacceptable
short-term risks toward site workers. Installation of the asbestos cap will prevent dispersion
of the asbestos. Removal of contaminated soil will similarly prevent exposure. The
groundwater controls will prevent exposure to contaminated groundwater.
\)
The baseline risk assessment for a residential scenario associated with this site estimated a
cumulative risk of 4 x 10-3. The residual risks after this remedy is estimated at 3 x 10-5
(residential scenario).
B. Compliance with .ARAR's
The selected remedy will comply with the federal and state ARAR's identified below. No
waiver of any ARAR is being sought. The ARAR's (identified in the RIfFS) for the 1100
Area are the following:
Chemical-Specific ARAR's
. Safe Drinking Water Act (SDW A), 40 USC Section 300, Maximum Contaminant
Levels (MCL's) for public drinking water supplies are relevant and appropriate for
setting groundwater cleanup levels.
. Model Toxics Control Act Cleanup Regulations (MTCA), Chapter 173-340 WAC,
Method A, Method B, and Method C risk-based cleanup levels are applicable for
establishing soil cleanup levels.
Action-Specific ARAR's
. Hazardous Materials Transportation Act (49 USC 1801-1813), Applicable for
transportation of potentially hazardous materials, including samples and wastes.
. National Emission Standards for Hazardous Air Pollutants (NESHAP),
(40 CFR 61), relevant and appropriate for closure requirements in relation to the
Horn Rapids Landfill.
. RCRA Land Disposal Restrictrictions (40 CFR 268) are applicable for off-site
disposal of BEHP-contaminated soils.
. Minimum Standards for Construction and Maintenance of Wells (Chapter 173-160
and 162 WAC) Applicable regulations for the location, design, construction, and
abandonment of water supply and resource protection wells.
G
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. RCRA Subtitle C (40 CFR 262) establishes standards for generators of hazardous
wastes for the treating, storage, and shipping of wastes. Applicable to the
transportation of hazardous wastes including the BEHP-contaminated soils.
J
Location-Specific ARAR's
. National Historic PreselVation Act (16 CFR 470, et. seq.)
o
D
. Endangered Species Act (40 CFR 402)
Other Criteria, Advisories, or Guidance to be Considered for this Remedial
Action (TBC's)
. EPA OSWER 9834.11, Revised Procedures for Planning and Implementing Off-
Site Response Actions, November 13, 1987. This directive provides procedures
for off-site disposal of CERCLA wastes.
. The Future For Hanford: Uses and Cleanup, The Final Report of the Hanfrod
Future Site Uses Working Group, December 1992.
C. Cost Effectiveness
The selected remedy provides overall effectiveness proportional to its cost. The cost for
Offsite Incineration of the BEHP-contaminated soil at the Discolored Soil Site appears to be
higher than for the other alternatives, but the other alternatives may not comply with the land
disposal restrictions.
D. Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Possible
The selected remedy utilizes permanent solutions and alternative treatment technologies
practicable for this site. Treatment was identified for the BEHP-contarninated soils at the
Discolored Soil Site. No other forms of practicable treatment were identified.
E. Preference for Treatment as a Principal Element
The selected remedy utilizes treatment which permanently destroys the BEHP in the soil.
The timeframe to achieve MCL's in groundwater via the selected remedy is approximately
25 years, which is longer than the timeframes (16 to 20 years) for remediation under
Alternatives GW-2A, GW-2B, GW-3A, and GW-3B. Because this groundwater is not used
as a drinking water source, there are no current potential risks to human health. When
considered against the other balancing criteria, the potential reduction in time (5 to 9 years)
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for the groundwater treatment alternatives is not sufficient to offset the additional costs
($4,000,000 to $8,000,000).
"
xu. DOCUMENTATION OF SIGNIFICANT CHANGES
v
DOE and EP A 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 selected remedy, as originally identified in the Proposed Plan, were necessary.
Although not a significant change, the cleanup level for the PCB-contaminated soil in the
Horn Rapids Landfill was lowered to 5 ppm from 50 ppm. This change results in an
estimated additional 265 cubic yards of soil being removed and was based largely on a
comment received during the public comment period.
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