PB96-964615
EPA/ROD/R10-96/151
August 1997
EPA Superfund
Record of Decision:
Hanford 100 Area (USDOE),
100-IU-l, 100-IU-3, 100-IU-4 & 100-IU-5
Operable Units, Benton County, WA
2/2/1996
-------
-------
DECLARATION OF THE RECORD OF DECISION
SITE NAME AND LOCATION
USDOE Hanford 100 Area J\JN
100-IU-l, 1 OO-IU-3, 1 OO-IU-4, and 1 OO-IU-5 Operable Units . ^ 4cleanup
Hanford Site Environ
Benton County, Washington
STATEMENT OF BASIS AND PUPPOSE
This decision document presents the selected action for portions of the U.S. Department of
Energy (USDOE) Hanford 100 Area, Hanford Site, Benton County, WA, which was 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). Specifically, the selected action will address waste sites
identified in the 100-IU-l, 1 OO-IU-3, 1 OO-IU-4, and 1 OO-IU-5 Operable Units. These four
operable units occupy portions of Benton, Franklin, and Grant Counties, WA. This decision is
based on the Administrative Record for the 100 Area and for the specific operable units.
DESCRIPTION OF THE SELECTED REMEDY
No further action is required at the 100-IU-l, 1 OO-IU-3, 1 OO-IU-4, and 1 OO-IU-5 Operable Units;
however, USDOE commits to the development and implementation of a Mitigation Action Plan
in coordination with the Natural Resource Trustees for any additional required mitigation
measures.
DECLARATION
It has been determined no further remedial action is necessary at the 100-IU-l, 1 OO-IU-3,
1 OO-IU-4, and 1 OO-IU-5 Operable Units. CERCLA expedited response actions (removals as
described in 40 CFR 300.415) perfon ied previously at these units from 1992 to 1994 have
cleaned up all contaminants of concern to below the WAC 173-340 Washington State Model
Toxics Control Act (MTCA) residential standards. The U.S. Environmental Protection Agency
(EPA) and Washington State Department of Ecology (Ecology) have determined these actions
are protective of human health and the environment. Because the no-action alternative will not
leave hazardous substances on-site above health-based levels, a five-year review does not apply.
HANFORD PROJECT OFFICE
F£B 1 6 1996
fj ENVfrfOUMfc-i.A PROTECTION
-------
Signature sheet for the Record of Decision for the USDOE Hanford 100-IU-l, 100-IU-3,
100-IU-4, and 100-IU-5 Operable Unit 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.
JohrD. Wagoner
Manager, Richland Operations
United States Department of Energy
Date
-------
Signature sheet for the Record of Decision for the USDOE Hanford 100-IU-l, 100-IU-3,
100-IU-4. and 100-IU-5 Operable Unit 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.
Chuck Clarke . Date
Regional Administrator, Region 10
United States Environmental Protection Agency
111
-------
Signature sheet for the Record of Decision for the USDOE Hanford 100-IU-l, 100-IU-3,
100-IU-4, and 100-IU-5 Operable Unit 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..P(\ U-,
Michael Wilson Date
Program Manager, Nuclear Waste Program
Washington State Department of Ecology
IV
-------
DECLARATION OF THE RECORD OF DECISION i
DECISION SUMMARY 1
1.0 INTRODUCTION 1
2.0 SITE NAMES, LOCATIONS, AND DESCRIPTIONS 1
2.1 Names And Locations I
2.2 Topography 2
2.3 Water Resources 2
2.4 Uses of Land and Natural Resources 2
2.5 Nearby Receptors J
3.0 SITE HISTORY .' 7
3.1 Hanford Site Background 7
3.2100-lU-l 7
3.3 100-W-3 .: 8
3.4100-W-4.. 9
3.5 100-W-5 9
4.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 18
5.0 SCOPE AND ROLE OF OPERABLE UNITS WITHIN SITE STRATEGY 20
6.0 SITE CHARACTERISTICS 20
6.1 Known or Suspected Contaminants 20
6.2 Groundwater. 20
6.3 Description Of Contamination And Affected Media 21
6.3.1100-IU-l 1 21
63.2 100-IU-3 21
6.3.3 100-IU-4 21
6.3.4 100-IU-5 22
7.0 SUMMARY OF SITE RISKS ; 22
7.1 General . ./. ". 22
7.2 100-IU-5 Human Health Evaluation Results 22
7.3 100-W-5 Environmental Evaluation Results ...23
8.0 EXPLANATION OF SIGNIFICANT CHANGES 23
9.0 DESCRIPTION OF THE NO-ACTION ALTERNATIVE 23
APPENDIX A - RESPONSIVENESS SUMMARY . A
-------
-------
DECISION SUMMARY
1.0 INTRODUCTION
The U.S. Department of Energy's Hanford Site was listed on the National Priorities List (NPL) in
July 1989 under 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 100 Area, the
200 Area, the 300 Area, and the 1100 Area.
The decision made in this document is the final remedy for the 100-IU-l, 100-IU-3, 100-IU-4,
and 100-IU-5 Operable Units, which are part of the 100 Area NPL site.
2.0 SITE NAMES, LOCATIONS, AND DESCRIPTIONS
2.1 Names and Locations
The Hanford Site is a 560-square mile federal facility located along the Columbia River in
southeastern Washington State. The region consists of the incorporated cities of Richland,
Pasco, and Kennewick (Tri-Cities) to the southeast of the site, and surrounding communities in
Benton, Franklin, Grant, and Adams Counties (Figure 1). The 100 Area is located in the
northern portion of the Hanford Site along the Columbia River, and covers approximately
468 km2 (180 mi2).
The area north of the Columbia River, known as the Wahluke Slope, covers approximately 364
km2 (140 mi2), and is separated from all other Hanford facilities by the river. The Wahluke
Slope is the location of the 39 waste sites which make up the 100-IU-3 Operable Unit. The 100
Area south of the Columbia River includes the other three units addressed in this Record of
Decision. The Riverland Rail Yard (100-IU-l Operable Unit) is 34 km2 (13 mi2) in size, and is
bordered by Washington State Highway 24 to the south and east, the Columbia River to the
north, and the Hanford Site boundary to the west. The Sodium Dichromate Barrel Landfill
(100-IU-4 Operable Unit) is 10.6 acres in size, and is located between the 100-D and 100-H
reactor areas. The White Bluffs Pickling Acid Cribs (100-IU-5 Operable Unit) are cumulatively
one-half acre in size, and are located about 2 km (1.2 mi.) west of the 100-F Reactor. Also south
of the river are nine USDOE nuclear reactors which were used for plutonium production between
1943 and 1987. These reactor sites will be addressed under separate Records of Decision.
-------
2.2 Topography
The topography of the 100 Area is marked by the Saddle Mountains to the north, and Gable
Mountain/Gable Butte to the south, and is transected by the Columbia River. Washington State
Route 24 traverses the Wahluke Slope from east to west. Semi-arid land with a sparse covering
of cold desert shrubs and drought-resistant grasses dominate the Hanford landscape. Several
wetlands are contained within the boundaries of the Wahluke Slope, mainly due to irrigation
drainage. The geologic structure beneath the 100 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 which have been warped and folded, resulting in protrusions cropping
out as rock ridges in some locations. Layers of silt, gravel, and sand known as the Ringold
formation form the middle level. The Ringold Formation shows a marked west-to-east variation
in the 100 Area. The uppermost level is known as the Hanford formation and consists of gravel
and sands deposited by catastrophic floods during glacial retreat.
2.3 Water Resources
Groundwater flow in the unconfined aquifer is generally toward its discharge point, the
Columbia River. Portions of the river's shoreline in the 100 Area are within the probable
maximum 100 year flood plain of the Columbia River (Figure 2). Forty percent of the area's
annual 6 1/4 inches of rain occurs between November and January. Due to irrigation practices,
and in part to the semi-arid conditions, three wetland areas are contained within the Wahluke
Slope.
2.4 Uses of Land and Natural Resources
Land use in the areas bordering the Hanford Site includes urban and industrial development,
irrigated and diy-land fanning, grazing, Native American uses, and designated wildlife refuges.
Industries in the area are mostly related to agriculture and electric power generation. Wheat,
corn, alfalfa, hay, barley, and grapes are major crops in the area.
Existing land use in the 100 Area includes the following land use categories: facility support,
waste management, undeveloped land, and wildlife areas. Facility support activities include
operations such as water treatment and maintenance of the reactor buildings. The waste
management land use designation results from past-practice waste sites located mostly in the
reactor areas. There are undeveloped lands located throughout the 100 Area. These areas are the
least disturbed and contain minimal infrastructure. An approximate 20 mile stretch of the
Columbia River is located within th^ 100 Area. Use of this portion of the river is mostly
recreational. The shoreline of the Columbia River is a valued ecological area within the Hanford
Site. Approximately 25% of the Wahluke Slope area is permitted to the U.S. Fish and Wildlife
Service, and is managed at the Saddle Mountain National Wildlife Refuge, with limited public
access. The remaining 75% is permitted to the Washington State Department of Wildlife, and is
operated as a State Wildlife Recreation Area, which is open to the public during daylight hours.
-------
Figure 1. Locations of 100-IU-l, 100-IU-3,100-IU-4, and 100-IU-5 Operable Units at the
Hanford Site.
i
Sodium Dichromate
Barrel Landfill (100-IU-4)
O
c i
2!
o I
O
-
Wahluke Slope
(100-IU-3)
H-06-C
Nike Missile
Control Site
H-06-L
Nike Missile
Launch Site
Adams Co.
••• • •••••• ma^—tmt
Franklin Co.
Riveriand Site
(100-IU-1)
\
White Bluffs Pickling
Acid Cribs (100-IU-5)
2, 4-D Disposal
Site
Hanford Site
Boundary
E9511002.1
-------
Figure 2. Area of Probable Maximum Flood, Hanford Site, Richland, Washington
Old Hanford
Townsite
Washington
Public Power
Supply System
Rattlesnake
Springs
1^ Battelle
300 Area PNL&
Westinghouse
Hanford
-.i Observatory
Areas Rooded
Hanford Site
Boundary
Advanced
Nuclear Fuels
VYe^t Richland
£9511002^
-------
2.5 Nearby Receptors
The closest population center to the 100 Area waste sites is the Tri-Cities area, with
approximately 100,000 residents. The Tri-Cities are located approximately 45 km (17 mi.) to
the southeast of these waste sites. To the west, north, and east, the 100 Area are bounded by
sparsely populated farming and ranching communities. To the south is the rest of the contiguous
Hanford Site.
Ecological surveys and sampling have been conducted in the 100 Area, and in and along the
Columbia River adjacent to the 100 Area. A summary of threatened and endangered species
under the Endangered Species Act from those studies is presented in Table 1. Bird, mammal,
and plant surveys were conducted and reported in Fiscal Year 1991 100 Areas CERCLA
Ecological Investigations. Current contamination data have been compiled from other sources,
along with ecological pathways and lists of all wildlife and plants at the site, including threatened
and endangered species. This information has been published in A Synthesis of Ecological Data
from the 100 Areas of the Hanford Site.
-------
Table 1. Endangered and Threatened Species Potentially Found on the Hanford Site1.
Species
Notes
Endangered Vascular Plants
Persistentsepai yellowcress
(Rorippa columbiae)
Northern Wormwood
(Artemisia campertris ssp
borealis var workskioldii)
Known to have a scattered distribution because of specialized habitat
requirements or habitat loss; generally occurs in marshy places; known to inhabit
wet shoreline of Hanford Reach in Benton County
Rare, local endemic species near the river; not known from the Hanford Site but
reported just to the north near Beverly, Grant County
Threatened Vascular Plants
Columbia milk-vetch
(Astragalus columbianns)
Hoover's desert parsley
(Lomatium tuberosum)
Locally endemic to area near Priest Rapids Dam; could potentially occur in
Northwest portion of the Hanford Site along the Columbia River
Locally endemic to south-central Washington, including Benton County; known
to inhabit rocky hillsides
Endangered Birds
2Aleutian Canada goose
(Branta canadensis leucopareia)
American white pelican
(Pelecanus erythrorhynchus)
2Peregrine falcon
(Falco peregrinus)
Sandhill crane
(Grus canadensis)
Only incidental occurrence at the Hanford Site.
Flocks have recently become common in the Columbia Basin during all seasons
foraging on fish, amphibians, and crustaceans, and roosting on islands
Breeds and winters in eastern Washington, inhabiting open marshes, river
shorelines, wide meadows, and farmlands; nests on undisturbed cliff faces; an
erratic visitor to the Hanford Site
Inhabits open prairies, grainfields, shallow lakes, marshes, and ponds; common
migrant during spring and fall in Washington; some known and suspected nesting
sites in eastern Washington; an occasional visitor at the Hanford Site
Threatened Birds
2Bald eagle
(Haliaeetus leucocephalus)
Ferruginous hawk
(Buteo regalis)
Regular winter visitor to the Columbia River, feeding on spawned-out salmon and
waterfowl; they roost in the 100 Areas and nest (unsuccessfully to date) along the
Hanford Reach
Inhabits open prairies and sagebrush plains, usually with rocky outcrops or
scattered trees; known to nest in Benton and Franklin Counties, including the
Hanford Site; rarely winter in Washington, but are known to occasionally forage
on small mammals, birds, and reptiles on sagebrush plains of the Hanford Site
Threatened Mammals
Pygmy rabbit
(Sylvilagus idahoensis)
Inhabits undisturbed areas of sagebrush with soils soft enough to permit burrows;
once known to exist on the Hanford Site west of the 200*Xreas plateau
'Additional information on threatened and endangered species and candidate species can be found in Hanford Site
National Environmental Policy Act Characterization (PNL-6415 Rev. 7), C. E. Gushing, ed., September 1995.
Indicates both state and federal designation.
-------
3.0 SITE HISTORY
3.1 Hanford Site Background
The Hanford Site was established during World War II as part of the "Manhattan Project" to
produce plutonium for nuclear weapons. Hanford Site operations began in 1943, with USDOE
facilities located throughout the Site and the City of Richland. 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 aggregate areas (the 100
Area, the 200 Area, the 300 Area, and the 1100 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). In May 1989, in anticipation of the NPL listing, USDOE, EPA, and
Ecology (the Tri-Parties) entered into a Federal Facility Agreement commonly known as the
Tri-Party Agreement. This agreement established a procedural framework and schedule for
developing, implementing, and monitoring remedial response actions at Hanford. The selected
remedy presented in this record of decision addresses the 100-IU-l, 100-IU-3, 100-IU-4 and
100-IU-5 Operable Units.
3.2 100-IU-l
The Riverland Rail Yard (100-IU-l Operable Unit, Figure 3) supported Hanford construction and
operation activities from 1943 until 1954, while decontamination of radioactive rail cars
continued until 1956. Included in this site are a 2,4-D pesticide container site, a rail yard
maintenance facility, and two former military installations with associated demolition debris.
In a June 1993 Action Memorandum, signed by the Tri-Parties, the USDOE agreed to perform an
expedited response action for the cleanup of the Riverland Rail Yard Maintenance Facility and
pesticide container sites, and closure of an empty munitions cache hole. Diesel contaminated
concrete and soil from the rail yard and pesticide sites were removed from the site for
bioremediation. Sampling results indicated that levels of the contaminants remaining in the soil
at the rail yard are below MTCA residential standards (Table 2). Radioactive decontamination of
this facility occurred around 1963, after which the maintenance facilities were dismantled and
sold. Follow-up radiological surveys were performed in 1977,1978, and 1993, revealing only
natural background levels. Also during the cleanup, a site containing 2,4-D pesticide containers
was discovered, sampled, and cleaned up to MTCA residential standards. No groundwater
contamination has been associated with the 100-IU-l Operable Unit.
-------
3.3 100-IU-3
Ownership of the Wahluke Slope is shared between USDOE and the U.S. Bureau of Land
Management. Under an agreement with USDOE, approximately 25% of the Wahluke Slope
(Figure 4) is managed as the Saddle Mountain National Wildlife Refuge by the U.S. Fish and
Wildlife Service, allowing limited public access. The remaining 75% is permitted to the
Washington State Depsrtm/at of Wildlife as the Wahluke Wildlife Recreation Area, and is open
to the public during daylight hours. This area was acquired for use as a military buffer zone
against potential hostile attacks on the 100 Area reactors. Several Anti-Aircraft Artillery
Batteries and three Nike Missile Sites were located on the Wahluke Slope. These sites were
decommissioned in 1960-1961, and demolished in 1974. Facilities handling radioactive
materials were not built here, and surveys performed revealed only natural background levels.
During 1989 and 1990, an investigation of the Wahluke Slope was performed to assess potential
health, safety, and environmental concerns raised by Ecology and the public. As a result of this
investigation, a number of sites associated with military or homesteading activities (prior to
1943) were identified as potential threats to the environment. Many of the sites were landfills for
former military installations. Based on the investigation, three of the Wahluke Slope sites, the
H-06-L Nike missile launch site, H-06-C Nike missile control site, and the 2,4-D pesticide
disposal site, were identified and included as part of the 100-IU-3 Operable Unit. During the
course of the investigation associated with the 100-IU-3 Operable Unit, 36 additional sites were
identified (Figure 4). Soil contamination in these areas resulted from historic use of petroleum
products and pesticides by the military.
USDOE prepared an engineering evaluation and cost analysis, North Slope (Wahluke Slope)
Expedited Response Action Cleanup Plan in 1993, regarding cleanup options applicable to the
Wahluke Slope sites. The Tri-Parties signed an Action Memorandum in 1994, requiring removal
of hazardous substances and proper abandonment of water wells. During 1994, a CERCLA
expedited response action was performed to remove any hazardous substances that remained in
the 39 sites on the Wahluke Slope. The cleanup results for the 39 100-IU-3 Operable Unit waste
sites are documented in the Close-Out Report North Slope (Wahluke Slope) Expedited Response
Action, Hanford Washington. Soil contaminated with the pesticide DDT and its associated
breakdown products was disposed of at a hazardous waste landfill in Arlington, OR. Petroleum
contaminated soil (PCS) was transported to a PCS treatment facility in Pasco, WA, for
bioremediation. Several 55-gallon drums of miscellaneous and hazardous substances were sent
to appropriate handling facilities. Non-hazardous trash, debris, and concrete were either returned
to their excavations or r?cycled. Contaminants remaining in the 1OO-IU-3 Operable Unit waste
sites were measured at levels below MTCA residential cleanup standards (Table 3).
Water wells were decommissioned in accordance with WAC 173-160 regulations (Minimum
Standards for Construction and Maintenance of Wells) to eliminate this potential contamination
path to groundwater, and to prevent interconnection of aquifers. No groundwater contamination
has been associated with the 1 OO-IU-3 Operable Unit.
-------
3.4 100-IU-4
The Sodium Dichromate Barrel Landfill is the only waste site located within the 100-IU-4
Operable Unit. The landfill is located in a small depression between the 100-D and 100-H
Reactor Areas (Figure 5). Little historical documentation of the site is available. The landfill
was used during the years of reactor operation for disposal of crushed, empty Sodium
Dichromate barrels. Sodium Dichromate was used as a corrosion inhibitor in the reactor cooling
water systems of the 100 Area reactors. The site is not known to have received significant
quantities of other waste types.
In 1992, Ecology and EPA recommended an expedited response action be performed at the
Sodium Dichromate Barrel Landfill, after which USDOE prepared an engineering evaluation and
cost analysis regarding remediation alternatives applicable to this unit (Sodium Dichromate
Barrel Landfill Expedited Response Action Proposal). The Tri-Parties signed an Action
Memorandum in 1993, requiring full excavation and removal of all buried materials from the
landfill.
Excavation, removal, and disposal activities took place between March and July, 1993.
Approximately 5,000 crushed drums were removed from the site, along with minor amounts of
asbestos-containing materials, two 5-gallon roofing tar cans, and a small amount of used oil and
grease. Soil sampling results indicated levels below MTCA residential cleanup standards were
achieved (Table 4). No groundwater contamination has been attributed to the 100-IU-4 Operable
Unit. Site radiation surveys performed revealed only natural background levels.
3.5 100-IU-5
The White Bluffs Pickling Acid Cribs Site (Figure 6) is the only site identified in the 100-IU-5
Operable Unit. The White Bluffs Area was the location of construction activities from about
1943 to 1959. After termination of construction activities, the White Bluffs construction support
facilities were torn down. Other than the historical information obtained in the HanfordSite
Waste Management Unit Reports, little is known about activities conducted at the site. It is
believed the cribs received waste streams (primarily nitric and hydrofluoric acid etch solutions)
from a pipe fabrication facility operating sometime between 1943 and 1959. The pipe
fabrication facility location is suspected to have been northeast of the cribs in 100-IU-2 Operable
Unit (White Bluffs Landfills and JA Jones 2 Construction site).
-------
In 1992, EPA and Ecology recommended that USDOE perform an expedited response action for
this site (White Bluffs Pickling Acid Cribs Expedited Response Action Proposal).
Characterization activities were conducted, determining the nature and extent of potential soil
contamination by collecting surface and subsurface soil samples. Test pits were also used to
verify the configuration of the piping system and provide a visual inspection of the crib
construction. The excavated material (soil, cobbles) was returned to the cribs after the samples
were collected.
Characterization activities indicated contaminants of concern were at levels below MTCA
residential cleanup standards (Table 5). No investigation of the groundwater was completed for
this unit due to its close proximity to other 100 Area operable units. The groundwater beneath
this unit will be investigated as part of the 100-IU-2 Operable Unit (White Bluffs Townsite). No
radioactive contamination has been associated with this unit.
10
-------
Figure 3. Location of Sites Within the 100-IU-l Operable Unit (Riverland Site).
Hanford Site
Boundary
E9511002.3
-------
Figure 4. Location of Sites Within the 100-IU-3 Operable Unit (Wahluke Slope).
Hanford Site
Boundary
Washington
Hanford Site
Ric
Vemita
Bridge
Reactor Sites (100 Area)
Suspect Site Locations
Approximate Scale: 1" = 14,000*
1. PSN 72/82
2. H-83C
3. H-81R
4. H-83L
5. PSN 80
6. Gravel Pit #47
7. Wahluke Schoolhouse
8. PSN 90
9. Asphalt Batch Plant
10. Gravel Pit #56
11. PSN 01 21.
12. Igloo Site 22.
13. H-06C 23.
14. PSN 04 24.
15. Radar Site 25.
16. Wasteway Cistern 26.
17. H-06L 27.
18. PSN 07/10 28.
19. Clay Pit Cistern 29.
20. Cow Camp Cistern 30.
Homestead Cistern
Shrapnel Site
H-12L .
Asbestos Pipe Site
H-12R
H-12C
Construction Dump
PSN 12/14
2, 4-D Burial Site
Wagor, Road Cistern
31. Bridge Overlook Dump Site
32. Stock Tank Cistern
33. 12-3 Cistern
34. Dune Homestead
35. Coyote Bait Can
36. Overtook Cistern
37. Stove Cistern
38. Lonetree Homestead
39. Hanford Firing Range
E9601071.1
-------
Figure 5. Location of the 100-IU-4 Operable Unit (Sodium Dichromate Barrel Landfill Site).
0 10002000 Feet
I I I
Sodium
Dichromate
Barrel Landfill
\
E9511002.5
-------
Figure 6. Location of the iOO-IU-5 Operable Unit (White Bluffs Pickling Acid Cribs).
100-IU-5
Operable Unit
White Bluffs
Pickling Acid
Cribs (100-IU-5)
100-IU-5 Operable Unit
Boundary
i i i I
100 200 300 Meters
E9511002.7
-------
Table 2. Analytical Data Summary for Residual Soil Contamination
at the 100-IU-l Operable Unit (Riverland Sites).
Contaminant of
Concern
Maximum
Concentration
Background
Cleanup Level Used
During Removal
2.4-D Pesticide Container Site
Aldrin (mg/kg)
Dieldrin (mg/kg)
0.00045
0.0036
ND
0.0012
0.05881
0.0625 '
Rail Yard Maintenance Facility
Diesel (mg/kg)
Heavy oil (mg/kg)
<2
<2
—
— •
2002
2002
ND Not detected at specified level.
1 . Based on Model Toxics Control Act (MTCA) Method B. Method B is applicable to all
sites and provides a method for calculating cleanup levels based on health risks
associated with a residential-use scenario.
2. Based on MTCA Method A. Method A identifies specific cleanup levels for 21 common
contaminants, based on health risks associated with a residential-use scenario. Method A
cleanup levels are intended for sites undergoing routine cleanup with relatively few
contaminants.
-------
Table 3. Analytical Data Summary for Residual Soil Contamination
at the 100-1U-3 Operable Unit (Wahlukc Slope).
Contaminant of
Concern
Maximum
Concentration
Average
Background
Cleanup Level
Used During
Removal
Site H-06-L (Landfill Site)
Arsenic (mg/kg)
Chromium (mg/kg)
Lead (mg/kg)
DDD-4, 4' (mg/kg)
DDE-4, 4' (mg/kg)
DDT-4, 4' (mg/kg)
Petroleum hydrocarbons
(mg/kg)
Heavy oils (mg/kg)
8.81
21.3
' 27.2 '
0.597
1.660
0.806
ND
ND.
3.30
8.10
—
0.00802
0.00171
0.00534
ND
ND
20'
100'
250'
4.1702
2.9402
l.OOO1
200'
200'
Site H-83-L (Debris Site)
Petroleum hydrocarbons
(mg/kg)
Heavy oils (mg/kg)
ND
ND
ND
ND
200'
200'
Site PSN-04 (Debris Site)
Petroleum hydrocarbons
(mg/kg)
Heavy oils (mg/kg)
ND
ND
ND
ND
200'
200'
Site PSN-90 (Oil Filter Site)
Petroleum hydrocarbons
(mg/kg)
Heavy oils (mg/kg)
ND
ND
ND
ND
200'
200'
NA Not applicable.
ND Not detected at specified level.
1 . Based on Model Toxics Control Act (MTCA) Method A (see definition in Table 2).
2. Based on MTCA Method B (see definition in Table 2).
-------
Table 4. Analytical Data Summary for Residual Soil Contamination at the
100-IU-4 Operable Unit (Sodium Dichromate Barrel Landfill).
Contaminant of
Concern
Chromium (mg/kg)
Maximum
Concentration
86.7
Background
—
Cleanup Level Used
During Removal
1001
1. Based on Model Toxics Control Act (MTCA) Method A (see definition in Table 2).
Table 5. Analytical Data Summary for Residual Soil Contamination
at the 100-IU-5 Operable Unit (White Bluffs Pickling Acid Cribs).
Contaminant of
Concern
Chromium (mg/kg)
Lead (mg/kg)
Nickel (mg/kg)
Maximum
Concentration
22.2
5.2
16.5
Background
9.8
3.5
9.9 .
Cleanup Level Used
During Removal
1001
2501
—
1. Based on Model Toxics Control Act (MTCA) Method A (see definition in Table 2).
-------
4.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
USDOE, Ecology, and EPA 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
known concerns based on community interviews. Since that time, several public meetings have
been held and numerous fact sheets have been disiributed in an effort to keep the public informed
about Hanford cleanup issues. The CRP was updated in 1993 and 1995 to enhance public
involvement.
The Proposed Plan for 100-IU-l, 100-IU-3, IOO-IU-4 and 100-IU-5 Operable Units was made
available to the public in both the Administrative Record and the Information Repositories
maintained at the locations listed below on June 26, 1995. Other documents relevant to this
decision have been previously deposited in the Administrative Record and Information
Repositories.
A fact sheet, which explained the proposed action, was mailed to approximately 1,500 people. In
addition, an article appeared in the bi-monthly newsletter, the Hanford Update, detailing the start
of public comment. The Hanford Update is mailed to over 5,000 people. The Proposed Plans
were mailed to all of the members of the Hanford Advisory Board.
ADMINISTRATIVE RECORD (Contains all project documents)
U.S. Department of Energy
Richland Field Office
Administrative Record Center
740 Stevens Center
Richland, Washington 99352
EPA Region 10
Superfund Record Center
1200 Sixth Avenue
Park Place Building, 7th Floor
Seattle, Washington 98101
Washington State Department of Ecology
Administrative Record
300 Desmond Drive
Lacey, Washington 98503
18
-------
INFORMATION REPOSITORIES (Contain limited documentation)
University of Washington
Suzzallo Library
Government Publications Room
Seattle, Washington 98195
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
Portland, Oregon 97207
DOE Richland 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 June 25 and 26, 1995.
Additional advertisements ran in the Tri-City Herald on July 23 and 25, 1995. The public
comment period was held from June 26, 1995, through August 9, 1995.
Responses to the written comments received during the public comment period that were
specifically relevant to the proposed plan are included in the Responsiveness Summary, which is
attached as Appendix A of this Record Of Decision. This decision document presents the
selected final action for waste sites in the 100-IU-l, 100-IU-3, 100-IU-4 and 100-IU-5 Operable
Units at the Hanford Site, Richland, WA, chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act, as amended by the Superfund
Amendments and Reauthorization Act, and to the extent practicable, the National Contingency
Plan. The decision for these sites is based on the Administrative Record.
19
-------
5.0 SCOPE AND ROLE OF OPERABLE UNITS WITHIN SITE STRATEGY
Due to its large size, the variety of potential contaminants, and the number of discreet sites, the
100 Area has been divided into 25 operable units. This Record of Decision addresses four of
these operable units, the 100-iU-l (Riverland Rail Yard), 100-IU-3 (Wahluke Slope), 100-IU-4
(Sodium Dichromate Barrel Landfill), and the 100-IU-5 (White Bluffs Pickling Acid Cribs)
Operable Units.
Based on the results of the expedited response, actions performed at these operable units,
USDOE, EPA, and Ecology have determined these sites pose no current or future unacceptable
risk to human health or the environment. Sampling performed indicated all contaminants had
been removed to below MTCA residential cleanup standards. No further action was required to
mitigate risk at these operable units. It was decided sufficient information had been collected
during the investigations to justify proceeding directly to the proposed plan.
Because these sites were determined not to pose a significant threat, or to be a significant source
of contaminants, USDOE, EPA, and Ecology have selected no further action as the final remedy
for these operable units. Because the alternative will not leave hazardous substances on-site
above health-based levels, a five-year review does not apply.
6.0 SITE CHARACTERISTICS
6.1 Known or Suspected Contaminants
As a result of previous investigations and field actions, all known sources or suspected sources of
contamination have been cleaned up to levels below MTCA residential cleanup standards.
Contaminants of concern included: the pesticides aldrin, dieldrin, and 2,4-D, as well as
petroleum contaminated soil (PCS) at 100-IU-l; asbestos-containing materials, organic solvents,
petroleum products, paint, grease, DDT and its breakdown products, and PCS at 100-IU-3;
chromium at 100-IU-4; and spent nitric and hydrofluoric acids at 100-IU-5.
6.2 Groundwater
In the 100 Area, the unconfined aquifer is primarily found in the Ringold Formation with
portions of the Hanfbrd Formation locally included. The upper confined aquifer is contained in
the basal Ringold Formation. The depth to groundwater ranges from approximately 12 meters
near the river to 25 meters. The Ringold Formation is made up of a series of alluvial sands and
gravels. The hydraulic conductivity for the Ringold Formation varies widely. It is estimated the
hydraulic conductivity ranges from 0.2 to 1.5 feet/day at the three sites south of the Columbia
River, and from 10 to 100 feet/day across the Wahluke Slope. Groundwater flow direction
beneath the 100 Area is generally toward the regional discharge point, the Columbia River. Flow
beneath the Wahluke Slope is heavily influenced by irrigation practices, including an east-west
irrigation canal which flows across the northern part of the area.
20
-------
6.3 Description Of Contamination And Affected Media
All known and suspected contaminant sources have been removed to below MTCA residential
cleanup standards (Tables 2, 3, 4, and 5). Inert materials and debris were either removed from
the site for recycling, or returned to the excavation. Site-by-site descriptions and dispositions of
remediation wastes are summarized below:
6.3.1 100-IU-l
At the Riverland Rail Yard Maintenance Facility: About 340 cubic yards of concrete were
removed and recycled; 430 cubic yards of diesel contaminated soil were removed from the site
for bioremediation; several 2,4-D containers were sampled and designated as non-hazardous; and
27 55-gallon drums containing soil with residual aldrin and dieldrin waste were designated as
non-dangerous waste and sent to the Hanford Central Landfill. Final sampling results were
below cleanup levels.
6.3.2 100-IU-3
At the Wahluke Slope site: 600 cubic yards of DDT contaminated soil and 242 cubic yards of
petroleum and 2,4-D contaminated soil were removed and disposed of at the Chemical Waste
Management Facility in Arlington, Oregon; 200 cubic yards of petroleum contaminated soil were
shipped to the New Waste Disposal Facility in Pasco, Washington, for bioremediation; five
55-gallon drums of waste contaminated with petroleum, pesticides, and paints were shipped to
the Hanford 616 Facility; 64 quarts of lubricating oil were recycled; one 55-gallon drum
containing a viscous tar-like material was shipped to the Hanford Central Landfill; and one
55-gallon drum containing paint waste was bulked with other paint waste and shipped to the
100-N Pad for disposition. Final sampling results were below cleanup levels.
6.3.3 100-IU-4
At the Sodium Dichromate Barrel Landfill: About 5,000 empty, crushed Sodium Dichromate
drums and the surrounding soil were excavated, and disposed of at the Hanford Central Landfill,
and did not designate as dangerous waste; minor amounts of asbestos-containing materials, two
5-gallon roofing tar cans, and a small amount of used oil and grease were sent to appropriate
handling facilities. Final sampling indicated contaminants of concern were at or below
background levels, and did not exceed cleanup levels.
Although groundwater monitoring results indicate the 100-HR-3 Groundwater Operable Unit has
elevated chromium levels, these levels have not been attributable to the 100-IU-4 Operable unit.
Groundwater beneath the 100-IU-4 Operable Unit is part of 100-HR-3 CERCLA Groundwater
Operable Unit, and currently has an operational pump and treat system that is removing
chromium from the groundwater.
21
-------
6.3.4 100-IU-5
At the White Bluffs Pickling Acid Cribs site: Sampling results indicated that, with the exception
of zinc, all site contaminants were below background concentrations. The elevated levels of zinc
were in one sample, and were attributed to a piece of galvanized metal that was scraped during
characterization activities, and not associated with former waste disposal activities. Final
sampling results were below cleanup levels.
7.0 SUMMARY OF SITE RISKS
7.1 General
The primary basis for the no action decision is that the results of soil analyses taken at the
100-IU-l, 100-IU-3, 100-IU-4, and 100-IU-5 Operable Units were compared with background
levels and MTCA residential values to determine whether the detected concentrations of
chemicals exceeded screening concentrations (Tables 2, 3, 4, and 5). While there were certain
constituents which were detectable above background concentrations, none of the contaminants
of concern exceeded applicable MTCA residential cleanup standards. Because MTCA
residential cleanup standards are designed to be protective at the 1 x 10"6 level (using MTCA
standard exposure assumptions), achieving these cleanup levels result in a risk that will be in, or
less than, EPA's acceptable risk range set in the NCP. Therefore, human health and ecological
risk assessments were not performed at the 100-IU-l, 100-IU-3, and 100-IU-4 Operable Units.
Results of the 100-IU-5 risk assessment are discussed below.
Ordnance surveys were required in the performance of the expedited response actions. A
Hanford site-wide ordnance and explosives waste (OEW) archive search (Ordnance and
Explosive Waste Records Search Report) was conducted by the U.S. Army Corps of Engineers,
revealing minimal chance of any undiscovered OEW at the 100-IU-l, 100-IU-3, 100-IU-4, and
100-IU-5 Operable Units, as well as on the rest of the Hanford Site. The report concluded no
further action is required for OEW mitigation at these operable units.
7.2 100-IU-5 Human Health Evaluation Results
All contaminants of potential concern except zinc were eliminated based on comparison to
background concentrations. The maximum zinc concentration detected at the site was
1070 mg/kg, which is well below the most restrictive zinc soil concentration in the human health
risk-based screening. Zinc was eliminated when compared to this risk based concentration,
therefore, based on the human henjtfc rsk assessment, there are no contaminants of concern for
human health risk associated with the Pickling Acids cribs.
22
-------
7.3 100-IU-5 Environmental Evaluation Results
Zinc concentrations were greater than Hanford Site background concentrations, and therefore
retained for ecological evaluation. The highest zinc concentrations were taken directly beside
underground pipes. The pipes were scraped during excavation and are likely the source of the
zinc. Because the zinc was localized, not listed as a contaminant disposed of at the site, and the
maximum detected zinc concentration was considered to be relatively non-toxic, zinc was not
considered further as a contaminant of concern for ecological risk.
8.0 EXPLANATION OF SIGNIFICANT CHANGES
The Proposed Plan for the 100-IU-l, 100-IU-3, 100-IU-4, AND 100-IU-5 Operable Units was
released for public comment in June 1995. The proposed plan identified no-action as the
preferred alternative. USDOE, EPA, and Ecology have reviewed all written comments
submitted during the public comment period. Upon review of these comments, it was
determined no significant changes to the selected remedy, as originally identified in the proposed
plan, were necessary.
9.0 DESCRIPTION OF THE NO-ACTION ALTERNATIVE
No further action is required at the 100-IU-l, 100-IU-3, 100-IU-4, and 100-IU-5 Operable Units;
however, the USDOE commits to the development and implementation of a Mitigation Action
Plan in coordination with the Natural Resource Trustees for any additional required mitigation
measures.
23
-------
-------
APPENDIX A-
RESPONSIVENESS SUMMARY
This responsiveness summary addresses public comments specific to the Proposed Plan for the
100-IU-l, 100-IU-3, 10C~!U~4, 100-IU-5 Operable Units. These written comments were
submitted to Ecology during the public comment period, which opened June 26 and closed
August 9, 1995.
LO SUMMARY OF PUBLIC COMMENTS
A total of two comments specific to the Proposed Plan for the LOO-IU-1, 100-IU-3, 100-IU-4,
100-IU-5 Operable Units were received by Ecology.
2.0 RESPONSE TO COMMENTS
2.1 100-IU-l Comment Summary:
Only two monitoring wells have been installed down-gradient of the former maintenance shop.
The direction of the groundwater gradient cannot be determined without at least three monitoring
wells. To ensure contamin.ation did not escape to groundwater, it is necessary to sample down-
gradient for diesel fuel and radionuclides.
Response:
The Riverland Kailyard Maintenance Shop foundation and soil were removed. Analytical
samples from both the drain area and the pit hoist indicated no contaminants above detectable
limits. As a result, USDOE, EPA, and Ecology recommended no further action at this facility
based on the fact that the soil below the facility indicates no contamination. EPA does not
believe placing another well at the 100-IU-l Operable Unit is necessary based on existing
information.
2.2 100-IU-3 Comment Summary:
What environmental characterization of the HenK^shed underground installations has been don?
at the 100-IU-3 Operable Unit?
Response:
As provided in Appendix C of the North Slope (Wahluke Slope) Expedited Response Action
Cleanup Plan, in the mid-1970's the approximately 20-foot deep bunkers at the missile sites
were blown up, and demolition debris from the surrounding structures was placed in the resulting
A
-------
depression. Prior to this action, any salvageable material (e.g., piping, electrical lines, pumps,
and other mechanical equipment) was removed from the site. As a cost saving measure,
analogous site data was used to predict the probability of residual contamination at Wahluke
Slope sites. The sampling of analogous sites on the Fitzner-Eberhardt Arid Lands Ecology
Reserve (ALE) provides strong evidence that the probability is very low of contamination being
associated with the demolished missile bunker structures on the Wahluke Slope. Therefore, it
was determined further characterization at these sites was not necessary.
USDOE performed pre-remedial action sampling of the NIKE missile bunker on the ALE in the
summer of 1994. These bunkers remain largely intact. Results of these sampling activities are
provided in A Compendium of Field Reports for the Fitzner-Eberhardt Arid Lands Ecology
Reserve Remedial Action, Hanford, Washington. Dewatering sumps, one located in each bunker,
were the only areas that exhibited contamination. PCB contamination of up to 150 jig/100cm2
was found on the walls of these sumps. Subsequent testing of the soils at three sump water
discharge points, found that the soil contained no evidence of PCBs, semi-volatile or volatile
organics, or metals. It was later determined that the source of PCBs was probably the oil in the
reservoirs of the existing operational sump pumps. As these pumps and their ancillaries would
have been removed from North Slope sites prior to demolition, the probability of contamination
via this route is very low.
Additionally, on the ALE site, soil gas surveys were performed at the drain field associated with
the blinker. As noted in the North Slope (Wahluke Slope) Expedited Response Action Cleanup
Plan, Appendix F, these drain fields could have received solvents that were disposed of through
the sewer system. The soil gas surveys gave negative results for volatile organics.
B
-------
-------
------- |