PB95-964605
EPA/ROD/R10-95/110
June 1995
EPA Superfund
Record of Decision:
Hamilton Island Landfill (USA/COE)
(OU 1), North Bonneville, WA
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FINAL
....... RECORDOF
DECISION
Hamilton Island,
Washington
Prepared for
m
Seattle District
U.S. Army Corps of Engineers
4735 East Marginal Way South
Seattle, WA 98124
March 1995
. . .
; .
. -
Woodward-Clyde
1500. Century Square
1501 Fourth Avenue.
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TABLE OFCOl\7ENTS
Section
DECLARATION OF THE RECORD OF DECISION
1.0
2.0
3.0
4.0
INtRODUCTION
SITE NAME, LOCATION AND DESCRIPTION
SITE mSTORY AND ENFORCEMENT ACTIVITIES
3.1
3.2
3.3
SITE mSTORY
ENFORCEMENT ACTIVITIES
RIlFS PROCESS .
SITE CHARACTERIZATION
4.1
4.2
SITE CHARACTERISTICS
4.1.1 Geology
4.1.2 Surface Water
4.1.3 Hydrogeology.
4.1.4 Ecology .
4.1.5 Land Use and Demographics
SOURCES OF CONTAMINATION.
. 4.2.1 Potential Areas of Contamination
4.2.2 Potential Contaminant Sources
4.3
NATURE AND EXTENT OF CONTAMINATION
4.3.1 Soils
4.3.2 Sediments
4.3.3 Surface Water
4.3.4 Groundwater
Page
IV
1-1
2-1
3-1
3-1
3-2
3-2
4-1
4-1
4-1
4-2
4-2
4-4
4-5 .
4-6
4-6
4-6
4-7
4-8
4-9
4-9
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TABLE OF CONTENTS (Continued)
6.0
7.0
8.0
9.0
Section
5.0
5.2
Page
SlTh1MARY OF SITE RISKS.
5-1
5.1
HUMAN HEALTH RISKS
5-1
. 5.1.1 Identification of Chemicals of Concern
5.1.2 Risk Characterization '
5.1.3 Human Health Risk Characterization Summary
5-2
5-4
5-5 .
ECOLOGICAL RISK ASSESSMENT
5-5
5.2.1 Exposure Assessment,
5.2.2 Ecological Chemicals. of Concern .
5.2.3 Ecological Risk Characterization Summary
5-6
5-7
5,-8
6-1
DESCRIPTION OF TIm SELECTED REMEDY
HIGHLIGHTS OF COMMUNITY PARTICIPATION
7.1
7.2
7-1
COMMUNITY RELATIONS DURING THE RI
COMMUNITY RELATIONS TO SUPPORT TIlE SELECTION
OF REMEDY .
7-1
7-3
DOCUMENTATION OF SIGNIFICANT CHANGES
8-1
9-1
RESPONSIVENESS SUMMARY
9.1
9.2
WRITTEN COMMENTS
VERBAL COMMENTS
9-1
9-3
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TABLE OF CONTENTS (Continued)
UST OF TABLES
TABLE 1
TABLE 2
TABLE 3
CHEMICALS AT OR ABOVE REGULATORY STANDARDS IN
. SOn.. SAMPLES .
METALS AT OR ABOVE REGULATORY STANDARDS IN
GROUNDWATER SAMPLES
DISTRIBUTION SCHEDULE OF. NEWS RELEASES AND
INFORMATION PAPERS
liST OF FIGURES
FIGURE 1
FIGURE 2
FIGURE 3
FIGURE 4
FIGURE 5
FIGURE 6
SITE LOCATION MAP
PROJECT AREA MAP
SCHEMATIC HYDROGEOLOGIC CROSS SECTION B TO B'
SURFACE WATER DRAINAGE
CELL LOCATIONS
SAMPLING LOCATIONS
UST OF APPENDICES
APPENDIX A WRITTEN COMMENTS ON PROPOSED PLAN .
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DECLARATION OF THE RECORD OF DECISION
Site Name and Location:
Hamilton Island
Skamania County, Washington
Statement of Basis and Purpose.
This. decision document presents the selected final remedial action for Hamilton Island,
Skamania County, Washington. This selecte4 remedy was chosen in accordance with the
Comprehensive Environmental Response, Compensation and Liability Act of 1980
(CERCLJ\), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA) and to the extent practical, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the administrative record for the site.
The lead agency for conducting RIfFS activities at Hamilton Island is the u.S. Army Corps
. of Engineers (US ACE) with the authority and responsibility for implementing the decisions
and directives of the Department of the Army under the Federal Facility Agreement. The
U.S. Environmental Protection Agency (EPA) and the State of Washington Department of
Ecology (Ecology) participated in the scoping of the site investigation and ~ the evaluation
of the remedial investigation data. The USACE. and EP A, in consultation with Ecology,
have jointly determined that no remedial action is necessary at this site. Ecology concurs
. .
with this determination.
,. ..-"
Description of the Selected Remedy
EP A has determined that no remedial action is necessary at Hamilton Island to ensure
protection of human health and the environment. This decision is based on the results of the
human health and. ecological risk assessments, which determined that conditions at the site
pose no unacceptable risks to human health or the environment. Long term monitoring is
not required.
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Declaration
EP A has detennined that no remedial action at the. site is necessary to protect human health
or the environment, and thus EPA's response at this site is complete. Therefore the site now
qualifies for inclusion on the Construction Completion List.
State of Washington Declaration
Ecology has concluded that the No Action Proposal protects human health and the
environment at Hamilton Island now and in the future. The state will de-list Hamilton Island
from the state's Hazardous Sites List.
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Signature sheet for the foregoing Hamilton Island Record of Decision between the
Department of the Army and the U.S. Environmental Protection Agency, with concurrence
by the State of Washington Department of Ecology.
{l.td aU--
Chuck Clarke
Regional Administrator, Region X
U.S. Environmental Protection Agency
E/gc)!e;s...-'
Date
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Signature sheet for. the foregoing Hamilton Island Record of Decision between the
Department of the Anny and the U. S. Environmental Protection Agency, with concurrence
by the State of Washington Department of Ecology.
~,
Ernest J. Harrell \
,
Major General, U.S.\Anny
Division Engineer
~
Date
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Signature sheet for the. foregoing Hamilton Island Record of Decision between the
Department of the Anny and the U.S. Environmental Protection Agency, with concurrence
by the State of Washington Department of Ecology.
MMy~~ ~~DireaDr
Toxics Cleanup Program .
Washington State Department of Ecology
;l.J. ~{19~
Date
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DECISION SUMMARy
Site Name and Location:
Hamiltonlsland .
Skamania County, Washington
1.0
INTRODUCTION
Hamilton Island was listed on the National Priorities List (NPL) in 1992 under the
Comprehensive Environmental Response, Compensation and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
, (SARA).
In accordance with Executive Order 12580 (Superfund Implementation) and the National Oil
and Hazardous Substances Pollution Contingency Plan (NCP), the U.S. ~y Corps of
Engineers (US ACE) perfonned a Remedial Investigation for Hamilton Island. The Remedial
Investigation (RI) characterized the nature and extent of contamination in soil, groundwater,.
. .
surface water, sediments and seeps. A Human Health Risk Assessment and an Ecological
Risk Assessment were conduced in 1994 to evaluate potential effects of the landfill
contaminants on human health and the environment, respectively. Based on the results of
the RI, the Human Health Risk Assessment and the Ecological Risk Assessment, no further
remedial action under CERCLA is necessary to ensure protection of human health or the
environment. .
This decision summary provides an overview of the site, site characteristics, summary of site
risks, a description of the selected remedy, highHghts of the Community Participation
Program, an explanation 'of sigriificant changes to the Proposed Plan issued for public
comment on November 4, 1994, and a responsiveness summary. This document has been
prepared in accordance with the EP A directive Guidance in Preparing Superfund Decision
Documents (OSWER Directive 9355.3-02).
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2.0
SITE NAME, LOCATION AND DESCRIPTION
The Hamilton Island NPL site is located between 1.5 and 2.5 miles downstream of the
Bonneville Dam on the Washington shore of the Columbia River (Figure 1). The site is
border~ on the east and south by the Columbia River, on the west and northwest by
Hamilton Creek, and on the northeast by the city of North Bonneville and a filled area which
was formerly Hamilton Slough. The area defmed as the Hamilton IsJand NPL site
encompasses approximately 226 acres and includes the Hamilton Island disposal area. and a
Wildlife Mitigation Area (Figure 2).
Prior to placement of excavated soil and other debris generated by the construction of the
Second Powerhouse for Bonneville Dam, Hamilton Island was. an elliptical 25O-acre area
sUITOunded by the waters of Hamilton Slough, the Columbia River, and Hamilton Creek.
The island was a low floodplain area with an approximate maximum elevation of 50 feet
above mean sea level (finsl).
The filling of Hamilton Slough connected Hamilton Island to the Washington shoreline of
the Columbia River, making the former island now the southwestern tip of a
northeast-trending peninsula. The area, still referred to. as Hamilton Island, is now an
elliptical mound. The island was constructed so that a ridge extends northeast to southwest
with the highest point located ~t the center of the island. The ground surface elevation varies
from the original ground surface of approximately 50 finsl to a maximum of approximately
160 fmsl in the Knoll Area. A topographic map of the site is shown on Figure 2.
Two portions of the site - the Knoll Area and the Wildlife Mitigation Area - are. fenced. The
Knoll Area is accessed from a gate at the eastern comer of the site at the Fisherinan Access
Road. The Wildlife Mitigation Area is accessed from a gate at the southeast comer of the
fenced area. Hamilton Island is accessible to vehicular traffic by an unimproved dirt road
extending south from the city of North Bonneville.
Hamilton Island is located in the designated Columbia River Gorge Natural Area. This area
. .
is a unique geographical feature with great ecological and biological importance. The
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~ - - ----- --~- - -- ---.--------- -
Columbia River in the vicinity of Hamilton Island. provides essential habitat for salmon,
steelhead trout, white sturgeon, American shad and the Pacific lamprey. The Columbia
River below Bonneville Dam is an area frequented by fishermen. The area in the vicinity
of Hamilton Island provides habitat for songbirds and raptors.
Within the soil and debris deposited on Hamilton Island, perched groundwater occurs as
discontinuous lenses that in some places discharges to the surface as seeps. Perched
groundwater on Hamilton Island is limited and insufficient to support water supply wells.
One aquifer has been identified at the site. It is described in Section 4.1.3.
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USGS GAUGING STATION
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NOTE: Some features shown are approximated.
o
2000
SCALE IN FEET
Project No,
93C0544/BOOO
HAMILTON ISLAND
Washington
SITE LOCATION MAP
Hamilton Island RifFS
FIGURE
1
Woodward-Clyde CI
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LEGEND
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BEACON ROCK
GOLF COURSE
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SCALE IN FEET
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. HAMILTON I~EA MAP
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FIGURE
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3.0
SITE HISTORY AND ENFORCEMENT ACTIVITIES
3.1
SITE HISTORY
Between 1977 and 1982, Hamilton Island was used as a disposal site for soil material
excavated during construction of the Bonneville Dam Second Powerhouse. Approximately
19 million cubic yards of soil and rock material were placed on Hamilton Island during
construction. In addition to soil and rock material, about 100,000 cubic yards of demolition
and construction debris and other mi~cel1aneous materials were disposed on the island. Based
on interviews and record reviews, it appears that occasional placement of this type of debris
material on the island occurred throughout construction of the Second Powerhouse. A
significant percentage of debris disposal occurred in an area known as the Knoll Area
towards the end of the construction period. During this .period, contractors cleared
miscellaneous debris from the construction site. Wooden concrete fonns, concrete, and steel
reinforcing rod are known to have been placed in the Knoll Area.
In 1986, a seep with discolored water was'discovered on the southeast side of the Knoll Area
by U5ACE. Analysis of a seep sample revealed the presence of metals, organic solvents,
pesticides, wood preservatives and organic chemicals. In 1987, the EPA and USACE
conducted a preliminary site survey, and collected ~e-.ep, sediment and soil samples. As a
result, it was detennined that hazardous and toxic chemicals may be present. The survey
estimated that contamination likely would be limited to 24 acres on'the southeastern side of
the Knoll Area.
In January 1988, EPA concluded that no immediate action was warranted at the site, but that
further investigations were necessary. Hamilton Island was placed on the Federal Facilities
Hazardous Waste Compliance Docket in the February 12, 1988 Federal Register.
The Portland District USACE conducted a field sampling program on Hamilton Island as
part of a Site Inspection (51) during the time period May 1988 to A~gust 1989. Surface
water, groundwater, and soil samples were collected and analyzed for various constituents
including volatile and semi-volatile organics, pesticides, polychlorinated biphenyls (PCBs)
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and metals. Concentrations exceeding risk-based screening criteria of some analytes were
detected in surface water and perched groundwater samples. Cadmium, copper, chromium,
lead and zinc concentrations that exceeded primary or secondary drinking water standards
were detected in unfIltered surface water samples. Toluene and benzoic acid concentrations
that exceeded freshwater Ambient Water Quality Criteria also were detected in surface water.
Total arsenic, copper, chromium andlead concentrations that exceeded primary or secondary
drinking water standards were detected in perched groundwater samples.
3.2
ENFORCEMENT ACTIVITIES
EPA proposed li~ting the site on the NPL under the NCP in the July 29, 1991 Federal
Register. Hamilton Island was placed on the NPL on October 14, 1992. The basis of the
. listing was a possible release to the Columbia River of runoff from a culvert with
concentrations of copper above freshwater Ambient Water Quality Criteria, a possible release
to the Wildlife Mitigation Area of runoff from a culvert with elevated levels of toluene and
zinc, and a possible releaSe to Hamilton Creek from a. seep with concentrations of arsenic
and lead above freshwater Ambient Water Quality Criteria. These possible releases were
deemed significant because the Columbia River, a designated National Scenic Area, is
regarded as a sensitive ecological area, and because Hamilton Island is located immediately
adjacent to the city of North Bonneville. .
Under CERCLA, the USACE entered into a Federal Facility Agreement with EPA Region
10 and Ecology on September 24, 1993 to complete a Remedial Investigation and Feasibility
Study (RIfFS) and to implement any subsequent remedial action that may be defmed in the
Record of Decision (ROD). The Federal Facility Agreement outlines the process and
interagency responsibilities for this study.
3.3
RIfFS PROCESS
The RI was. conducted by the Portland District of USACE with assistance from the Seattle
District and their contractors. The RI process included:
. Site Characterization
. Human Health and Ecological Risk Assessments
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. Community Participation Program'
. Support for the Selected Remedy
These components of the RI process are presented in Sections 4.0 through 7~0. No
CERCLA removal or remedial actions had been taken at Hamilton Island prior to this RI.
A Feasibility Study that developed Remedial Action Objectives and evaluated alternatives
was not perfonned at this site since the RI indicates no remedial actions are necessary to
. ensure protection cf human health or the environment.
.--
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4.0
SITE CHARACTERIZA.TION
Data and information collected during the RI were used to evaluate potential adverse risks
to human health and the environment, and support selection of the preferred remedy: These
data and information are summarized in this section. A characterization of the surface water,
geology, hydrogeology and ecology are presented in Section 4.1. Section 4.2 describes
potential sources of contamination, and the nature and extent of contamination is discussed
in Section 4.3.
4.1
SITE CHARACTERISTICS
4.1.1 Geology
The original ground surface of Hamilton Island was the remnant of a river terrace. The
sediments comprising the terrace indicate that it. originated as an outwash plain deposited
approximately 800 years ago after the Columbia River breached the Bonneville Landslide.
The site stratigraphy is shown in Figure 3 and a discussion of each unit is presented below.
Hamilton Island Fill
The fill placed on the island between 1978 and 1982 consisted primarily of material
excavated during construction of the Bonneville Dam. The fill material is composed of soils
and large boulders from several geologic units. It is an unsorted and unconsolidated mixture
of well-weathered material.
Excavation and drilling performed during the RI exposed some minor- amounts of
. construction and demolition debris throughout Hamilton Island. It was concentrated,
however, in the Knoll Area. Debris encountered in the Knoll Area included plastic, metallic
items such as cable and wire, lumber, household refuse, external automobile parts
. .
(reflectors, mirrors, etc.), steel shapes and pipe, rebar, and other miscellaneous benign
. .
items. With the exception of a few rags stained with motor oil and an automobile oil filter,
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no wastes containing. solvents, wood preservatives, paint, oil, degreasers, or any other
potential contaminants were observed.
Recent River Deposits (RRJ)) Unit
The RRD unit is the uppennost on-site geologic unit underlying the fill material. The unit
is comprised of materials deposited after the Bonneville Landslide. The unit consists of
stratified layers of alluvial sediments ranging in size from clay to very large boulders. The
top of the unit ranges from approximately 25 feet mean sea level (finsl) onthe south side of
the island near the river to 45 finsl on the north side. The base is at approximately 15 fms!.
Pre-Bonneville Landslide Alluvium (PBA) Unit
The PBA unit underlies the RRD unit and can be distinguished from the RRD unit by a lack
of slide materials which indicates the PBA unit was deposited prior to the Bonneville
Landslide. The top of the PBA unit is located at about 15 finsl and the bottom elevation is
unknown. The PBA unit can be divided into three general subunits: PBA-l, PBA-2, and
PBA-3. PBA-l consists of micaceous sands and blue silts. PBA-2 unit consists of abundant
gravel interbedded with layers of rme to medium, clean, micaceous sands. PBA-3 unit,
which is the lowennost PBA .subunit, consists of sand and fme~grained materials similar to
those in PBA-l. PBA-l and PBA-2 are shown on Figure 3. None of the borings drilled
during the RI investigation penetrated thePBA-3 unit, ann it is not included in the geologic
cross-section (Figure 3).
4.1.2 Surface Water
Surface water runoff from Hamilton Island collects in several ditches that direct the runoff
into either the Columbia River, Hamilton Creek, the Rail Pond, or the Wildlife Mitigation
Area. . Surface water drainage patterns are shown on Figure 4.
4.1.3 Hydrogeology
One groundwater aquifer has been identified at Hamilton Island. This unconfm~ aquifer
is located in the RRD and the PBA units. For conceptual purposes, the aquifer is separated
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into an upper and lower portion because the screening intervals for the 12 onsite wells range
over a 16O-foot vertical distance (12 to -147 fmsl), and a vertical hydraulic gradient has been
- observed. -
Groundwater recharge in the study area occurs as infiltrating precipitation and lateral inflow
from the Columbia River and Hamilton Creek. Groundwater discharge in the study area
occurs as evapotranspiration, seeps along Hamilton Island, and lateral flow to the Columbia
- .
River and Hamilton Creek. The Columbia River is a significant recharge/discharge point.
Near Hamilton Island, the Columbia River bottom is approximately -65 fInsl, which may
enhance the hydraulic connection between the river and deeper groundwater.
Because of the proximity of the Columbia River and the frequent and large changes in river
level, or stage, caused by operation of the Bonneville Dam, the groundwater flow system at
the site is variable. At the time of data collection, groundwater was recharging the river.
In the upper portion of the aquifer, a groundwater velocity of approximately 0.02 ftIday was
estimated, and groundwater was flowing in a southwest direction. In the -lower portion of
the aquifer, a velocity ranging from 0.1 to 0.3 It/day was estimated; groundwater was
flowing in a southeast direction.
A consistent upward flow direction was observed on the northern portion of the island, and
both an upward and downward flow direction were observed at the well pairs located closer
to the river. From the available grour.dwater data, a vertical. groundwater velocity was
'estimat~ ranging from an upward velocity of -0.2 ftlday to a downward velocity of
0.1 ftlday.
Groundwater movement at Hamilton Island is highly influenced by changes in the level, or
stage, of the Colu'mbia River. Because the available groundwater elevation data correspond
to a small range of river stage elevations (12 to 16 fmsl), and the Columbia River stage can
vary over a much wider range (6 to 30 fmsl), the modeled groundwater, flow direction,
hydraulic gradient, and velocity reflect only one possible scenario with regards to-
groundwater flow characteristics. The extent of the variability of the flow characteristics
cannot be quantified with the available data. In - addition, the model is probably not
representative of groundwater conditions away from the river.
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- -- ---~_.-
. -
4.1.4 Ecology
Hamilton Island is located in the designated Columbia River Gorge National Scenic Area.
This area is a unique geographical feature with great ecological and biological importance.
The plant and animal communities in the gorge are presented below.
Flora
Plant community types within the gorge exhibit a ~sition from dry sagebrush and
ponderosa pine communities of the eastern Cascades to moist Douglas f]I communities of the
western Cascades. Three overlapping zones of vegetation occur in the gorge and in the
vicinity of Hamilton Island. A river bank zone occurs along the banks of the Columbia
River; a floodplain zone lies generally south of the Burlington Northern Railroad trackS
between the old city of North Bonneville and Beacon Rock; and an upland zone occurs north
of the railroad. Hamilton Island is located in the river bank and. floodp~ zo.nes described
below. There are no threatened or endange~ plant species on Hamilton Island.
The river bank zone vegetation, located along the north bank of the Columbia River in the
site vicinity, is generally limited to woody species. Fluctuations in water levels, high
currents, and shallow, rocky soils limit the growth of these species to shnib fonns.
The floodplain zone includes a variety of riparian, pasture, and upland communities that have
been greatly influenced by. grazing, logging, and recreational activities. Pasture and riparian
communities are generally located nearest the river on well-watered sandy or loamy soils.
Wetlands located .within the Hamilton Island NPL boundaries include the rail pond, on the
western point of HaInilton Island, the riparian and flood plain areas adjacent to Hamilton
Creek and the Columbia River, and small isolated areas adjacent to seeps near the fill area
on Hamilton Island.
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Fauna
The Columbia River in the vicinity of Hamilton Island provides essential habitat for
anadromous chinook, coho, chum, and sockeye salmon; steelhead trout; white sturgeon; and
American shad and Pacific lamprey.
The shallow, rocky soils, fluctuating water levels, and limited vegetation growth typical of
the river bank vegetation zone support a limited diversity and abundance of wildlife species.
The more protected shallow water areas near the mouth of Hamilton Creek contain aquatic
plants, provide more abundant and diverse food and cover resources, and thus, are more
productive habitats.
The floodplain vegetation zone includes the riparian, shrub/scrub, grassland communities,
and wetland habitats. Communities of small mammals, songbirds, raptors and large
mammals are abundant in ~s ~. . The floodplain zone also provides habitat for several
Species of special concern. The Canada gooSe, bald eagle; osprey, great blue heron, and the
American peregrine falcon may feed and rest in this part of the gorge. Canada geese and
ducks also nest, brood, rest, feed and winter in this area. Although some federally listed
threatened or endangered species use Hamilton Island for feeding and resting, none reside
permanently on the site.
4.1.5 Land Use and Demographics
The city of North Bonneville is the only development withID the study area. The city's
population is estimated to be approximately 400 persons. The municipal water supply is
completely reliant on one active groundwater supply well located in the city. Approximately
11 private groundwater supply wells are located within a I-mile radius of the NPL site
boundary. The municipal well and three of the private wells were sampled during the RI
field investigation. Results are discussed in Section 4.3.4. .
The Columbia Gorge is a transportation corridor through the Cascade Range for river
navigation, railroads, and highways. The gorge, a federally designated National Scenic
Area, is an important resource for tourism and recreation. Under this designation, future
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land use development is controlled. The city of North Bonneville is designated as one of the
few urban areas in the gorge where future development can occur.
4.2
SOURCES OF CONTAMINATION
The approximately 19 million cubic yards of soils and other earthen materials deposited on
Hamilton Island during construction of the Bonneville Dam Second Powerhouse were
naturally occurring, clean material not known or suspected to be con~inated by any
anthropogenic sources. Demolition and construction debris (approximately 100,000 cubic
yards) buried with soil material are the potential sources of contamination at Hamilton
Island. The following discusses pot~ntial areas of contamination and types of debris that may
be sources of contamination.
4.2.1 Potential Areas of Contamination
In large part, field investigations for the RI were designed to locate, delineate, and
characterize areas of potential debris placement. For this reason, the island was subdivided
into six general areas of investigation according to the history of fill placement: Cells 1
through 5, and Parcel B (Figure 5). Within these six general areas are locations where
demolition and construction debris are thought to be concentrated. These locations have a
higher.probability of being sources of contaminants, and include the Knoll Area in Cells 1
. .
and 2, two areas believed to contain demolition debri~ from the former city of North
Bonneville(TDA #2 in Cell I and IDA #1 in Cell 5), and a Construction Staging Area
along the northern edge of Hamilton ~sland in Parcel B. The .results of pre-RI data, aerial
photographs, persOnnel interviews, and a geophysical survey were used to refme the location
of previously identified areas and to identify other potential debris disposal areas. The
sampling program was designed to evaluate potential source areas by means of soil borings,
monitoring wells, test pits, and trenches.
4.2.2 . Potential Contaminant Sources
The demolition debris and construction wastes disposed at Hamilton Island are believed to
consist predominantly of wood, concrete, and steel rebar. . No evidence of d~sposal of
hazardous substances was revealed by either the personnel interviews or examination of
-------
aerial photographs; Some refuse was observed on the ground surface within the study area,
apparently originating from unauthorized disposal of municipal waste. It is possible that
small quantities of hazardous substances could have been included with disposed debris or
illegally-dumped municipa) waste.
4.3
NATURE AND EXTENT OF CONTAMINATION
Because of uncertainty about procedures and protocols used for sample collection, laboratory
analysis, ~d monit"ring well installation and development, the data collected from 1986 to
1990 were not used for either the RI risk assessments or to evaluate the nature arid extent
of potential contamination at Hamilton Island.
During the RI field investigation, 168 soil and 87 water samples were collected from the
sampling locations shown on Figure 6. Soil and sediment samples were analyzed for volatile
organic compounds (VOCs) , semi-volatile organic compounds, organochlorine pesticides,
, polychlorinated biphenyls (PCBs), t<;>tal petroleum hydrocarbons (TPH) and metals. Surface
water, groundwater and seep samples were analyzed for the same organic compounds, as
well, as total and dissolved metals and selected water quality parameters. To assess the
presence of contaminants, analytical results were compared with background metal
concentrations and regulatory-derived criteria. (See the "Hamilton Island Disposal Site
Background Study Report, Bonneville Dam Area" in the Administrative Record for values
of naturally-occurring metals in the Hamilton Island region.) Regulatory-derived screening
criteria used in the RI are potentially applicable federal and state risk-based concentrations
that are considered protective of human health and the environment., This is discussed
further in Section 5.1, Summary of Site Risks.
The criteria used for this RI are EPA Region 3 risk-based concentrations (RBCs) and
Ecology Model Toxic Control Act (MTCA) Method B target cleanup goals. EPA Region
3 RBCs are the most current screening-level criteria for any EPA region and are used as a
reference by EPA Region 10. .' "
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4.3.1 Soils
During the RI field investigation 168 soil samples were collected from 21 soil borings, 16
test pits, and four trenches. Samples were taken at depths ranging from 0.5 feet below
ground surface to a maximum depth of 121.5 feet below ground surface. Evidence of
anthropogenic contaminants in site soil samples is limited to isolated volaQ.1e and semi-
volatile organic comp(:mnds at relatively low concentrations, and generally isolated
occurrences of petroleum hydrocarbons. Organochlorine pesticides and PCBs were not
detected in any soil samples.
Several volatile and semi-volatile oIganic compounds were detected in soil samples, mostly
in the Knoll Area. Some of these compounds ~y be derived from associated petroleum
hydrocarbons. All detected volatile and semi-volatile compounds in. soils are below
. .
screening criteria concentrations with the exception of four semi-volatile compounds in two
field duplicate samples (one from the Knoll Area and one from Parcel B). The detections
only slightly exceed the criteria, and the compounds were not detected in the associated
primary samples. See Section 5.1.1 for discussion of these detections.
Total petroleum hydrocarbons in (TPH) soils are the most significant chemical contaminants
found on the Hamilton Island NPL site. Isolated occurrences of TPH were detected in soil
throughout tbe site. . The regulatory criterion (MTCA Method A cleanup level of 200 mg/kg)
for TPH was exceeded only in the Knoll Area (four samples at three locations).
To evaluate the extent of petroleum hydrocarbons in soils, Ecology suggested that additional
samples be collected in the Knoll Area. Although petroleum hydrocarbons are not regulated
as a potential contaminant of concern by EP A under CERCLA, they are regulated by
Ecology under MTCA. Based on the additional sampling, it was concluded that
contamination exists sporadically in a small, isolated area, and that contamination was not
widespread in the Knoll Area or elsewhere on Hamilton Island. Because no definable area
. .
of contamination could be found, Ecology advised the USACE that no further investigation
or removal of contaminated soil would be required under MTCA.
With the exception of manganese, metal results for soils are below either screening criteria
concentrations or site-specific background concentrations. About one-half of the manganese
-------
results exceeded the screening criterion concentration. Observed concentrations of
manganese in soils are, however, consistent with derivation from the basaltic lithologies that
typify the Columbia River Gorge.
4.3.2 S~ents
No VOCs, organochlorine pesticides, or PCBs were detected in the nine sediment samples
collected during the RI field inyestigation. The semi-volatile compound bis(2-
ethylhexyl)phthalate was detected in one sample. This compound is considered to be a
sample contaminant introduced either during sampling or in the laboratory. Petroleum
hydrocarbons were detected in one sample below the screening criterion concentration. The
sample site is located next to a well-traveled public access road and the petroleum
hydrocarlx>Ds may be related to non-site sources. Results for metals detected in site sediment
samples generally do not differ significantly from the background sediment sample.
4.3.3 Surface Water
Two sampling rounds were conducted at eight sutface water and five seep sampling
locations. No organochlorine pesticides, PCBs, or petroleum hydrocarbons were detected
in sutface water samples, with the exception of a single detection of a VOC and a semi-
volatile organic compound. The VOC, caIbon disulfide, was detected in the Rail Pond
sample. There are no sutface water screening criteri~ for caIbon disulfide. The compound
was not detected in any site soil, sediment, seep or groundwater samples and is likely not
an anthropogenic contaminant derived from the site. Analytical results for water quality
parameters for this sample suggest that chemical conditions in the Rail Pond may allow
. natural formation of caIbon disulfide. The semi-volatile organic' compou~d bis(2-
ethylhexyl)phthalate was detected in one sample. The compound is considered to be ~ .
sample contaminant introduced either during sampling or in the laboratory.
No VOCs, semi-volatile organic compounds, organochlorine pesticides, or PCBs were
detected in seep samples from the site, with the exception of 1,2-dichloroethane detected in
one sample from the Knoll Area. The 1,2-dichloroethane concentration was less than the
most conservative screening level criterion.
-------
Petroleum hydrocarbons were detected in one sample in the Knoll Area. The contamination
may be related to petroleum hydrocarbons nearby or, alternatively, associated with heavy
equipment traffic on the adjacent Knoll Area access road during the RI. Screening criteria
are not available for petroleum hydrocarbons in surface water.
Few surface water and seep samples exceed conservative screening criteria concentrations
for metals. Zinc slightly exceeded the criteria in one surface water sample from the Rail
Pond. One seep sample in the Knoll Area exceeded the most conservative criteria for copper
and zinc. This seep and one other in the Knoll area also exceeded the criteria for iron. The
low frequency of detection indicates that these metals are not significant or pervasive in
surface water at the site.
4.3.4 Groundwater
Two sampling rounds were conducted at 16 groundwater wells. Organic.. parameters were
detected only in perched groundwater samples. Analytical results do not indicate any
significant hydraulic connection between the perched groundwater and the underlying
. regional aquifer. No VOCs, semi-volatile organic compounds, organochlorine pesticides,
PCBs, or petroleum hydrocarbons were detected in groundwater samples from the aquifer
beneath the site. .
Toluene and 1,2-dichloroethene were detected in one perched groundwater well at low
concentrations. The two compounds were not detected in any seep or surface water samples
from the site. These VOCs may be related t<] isolated occurrences of small quantities of
contaminants within Hamilton Island fill materials. The concentrations reported for these
. compounds were well below the most conservative screening criteria concentrations.
Acetone was detected in one sample, and is considered a sample contaminant introduced in
the laboratory.
Petroleum hydrocarbons were detected in one perched groundwater well at a concentration
slightly above the detection limit, and are probably related .to TPH reported in one soil
sample from the boring.
-------
As with surface water, there were few exceedances of conservative screening criteria for
metals in groundwater samples. Most exceedances of screening criteria are associated with
samples exhibiting high total suspended solids from the fIrSt round of sampling, and include
arsenic, lead, manganese, nickel, and vanadium. This is discussed further in Section 5.1.1.
-------
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SCHEMATIC HYDROGEOLOGIC CROSS SECTION 8 TO 8'
Hamilton Island RifFS
FIGURE
3
Project No.
93C0544/8000
HAMILTON ISLAND
Washington
Woodward-Clyde .,
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-------
LEGEND
..:.'
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AGURE
-------
LEGEND
----
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+
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CONTOUR IN1£RVAL: 10 F'EET .
300 0
SCALE IN FEET
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HAMILTON I8lAND AI"'.
AGURE
-------
LEGEND
.
III
(II
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SEEP
TEST PIT
SOIL BORING
SOIL BORING MET REFUSAL AND
REPLACED WITH TEST PIT
. GROUNDWA TER MONITORING WELL
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o GROUNDWA TER MONITORING WELL
(UPPER PORTION OF AQUIFER)
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SAMPLING LOCATIONS
HAMilTON laLAND RI/Fa
FIGURE
6
Pro,," No.
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5.0
SUMMARY OF SITE RISKS
Human health and ecological risk assessments were conducted for Hamilton Island. The risk
assessments were conducted in accordance with EPA's Risk Assessment Guidance for
Superfund, Volume I: Human Health Evaluation Manual and Volume TI: Environmental
Assessment Manual and .EP A national guidance. The risk assessment methods and results
.are summarized in the following sections.
5.1
HUMAN HEALTH RISKS
The human health risk assessment evaluated potential risks associated with exposure to
chemical contaminants from Hamilton Island. The assessment considered potential exposure
to contaminants in groundwater, surface water, soil and sediment. . Both carcinogenic (i.e;,
causing the development of cancer) and non-carcinogenic (i.e., direct toxic effects on organ
systems, reproductive and developmental effects) risks were evaluated. Risks were estimated
for current and future land use in the vicinity of Hamilton Island. The assessment estimated
hypothetical risks for people residing or recreating at or adjacent to Hamilton Island.
To ensure that the potential health risks would not be underestimated, a conservative
approach was used. Reasonable conservative e~.;'T1ates and assumptions were used to
enhance confidence in the conclusions of the risk assessment. A screening-level approach
was adopted that is consistent with EP A guidance for risk assessment and with project goals.
Based on preliminary evaluation of data, EP A, Ecology and USACE agreed that a full .
baseline risk assessment was not warranted for this site. The screening-level risk evaluation
is protective of human health because it is based on comparison of the maximum detected
concentrations (which overestimates exposure concentrations) to EP A conservative risk-based
. .
screening values appropriate for long-term residential exposure. EPA's risk-based screening
values are derived from standard EP A exposure assumptions for residential use and are
.. c3Jculated at the lxlO-6 exposure concentration for carcinogens and a HaZard Quotient (HQ)
equal to 1.0 for non-carcinogens. Key steps in the risk assessment are outlined below.
-------
5.1.1 Identification of Chemicals of Concern
Potential chemicals of concern (COCs) are waste-related chemicals at Hamilton Island that
may pose health risks to humans who come into contact with them. COCs were identified
through evaluation of RI sampling results for groundwater, surface water, soils and
sediments. Potential chemicals of concern in<;:lude organic compounds, some metals and
petroleum products.
To identify COCs, maxnnum concentrations of potential chemicals of concern. were
compared to media-'specific Risk Based Concentrations (RBCs). Chemicals whose maximum
concentrations are below protective RBCs are not considered a health risk and are not
evaluated further. Few potential chemicals of concern were detected. Most detected
concentrations were below conservative (health-protective) screening criteria.
Analytical results from both surface and subsurface soil samples were compared to screening
criteria. In soil, several carcinoge~c polyaromatic hydrocarbons (PARs) were detected in
two samples. PARs were below detection limits in all other soil samples. The individual
concentrations somewhat exceed the MTCA Method B screening level, but they are below
the EPA Region 3 sCreening level, except for benzo(a)pyrene, which exceed the EPA
Region 3 screening criteria .by a factor of 2.4 as shown in Table 1. The risk of this single
benzo(a)pyrene occurrence using the very conservative EPA exposure parameters is only
3xI0-6. Unde!: CERCLA and the NCP, remediation is not required if cancer risks do not
. .
exceed Ixl04. The COCs for soils ~ benzo(a)anthracene, benzo(a)pyrene,
benzo(b )fluoranthene and chrysene. Although manganese was detected in several soil
samples in concentrations above the most conservative screening criteria, manganese is not
considered an environmental contaminant at Hamilton . island because it is naturally occurring
at comparable concentrations.
Table 1. Chemicals At or Above Regulatory Standards in Soil Samples (*ppm)
Total Highest # Samples Washington
Number of Level' Above EPA State
Chemical Samples Measured Standards Criteria Standards
Benz.o( a) anthracene 168 0.2 1 0.88 0.14
Benz.o(a)pyrene 168 0.21 1 0.088 0.14
Benz.o(b )fluoranthene 168 0.2~ 1 0..88 0.14
Chrysene 168 0.2 1 88 0.14
*ppm = parts per million or mglkg
-------
Analytical results of groundwater from shallow and deep wells in the' regional aquifer were
compared to screening criteria protective of long-term domestic use. Perched water 00
Hamilton Island is present in an insufficient quantity to sustain a yield of greater than 0.5
gallons per minute and as such is not considered a potential future drinking water source .
. .
under the Washington State drinking water codes [WAC 173-340-720 (l)(a)(ii)] and MTCA
[W AC 173-303-720]. Perched water therefore was not evaluated since comparison of
perched water samples with criteria developed for the protection of drinking water are not
applicable. Five metals - chromium, manganese, nickel, vanadium and arsenic - were
detected in groundwater samples at concentrations exceeding conseivative screening criteria
for drinking water. With the exception of manganese, all exceedances are associated with
unfiltered samples. All of these metals occur naturally in soils and rock and can be
associated with suspended particulate or colloidal matter in groundwater. These.metals are
not considered groundwater contaminants. There were no volatile or semi-volatile
. .
compounds detected in groundwater at levels exceeding screening values. Specific chemicals
in groundwater that were detected at levels that exceed screening criteria are listed in
Table 2.
Table 2. Metals At or Above Regulatory Standards in Growulwater Samples (*ppm)
Total # Highest # Samples Washington Federal
of Level Above State Drinking Water
Metal Samples Measured Standards EP A Criteria Standards Standards
Arsenic '26 0.019 3 0.000038 0.00005 0.05
Chromium 26. 0.12 1 0.18 0.08 0.1
Manganese 26 2.2 6 0.18 0.08 -
Nickel 26 0.31 1 0.73 0.32 0.1
Vanadium 26 0.27 2 0.26 . 0.11 -
"'ppm = parts per million or mg/l
No chemicals were detected in surface water or seep water above conservative health-based
. .
screening values. The screening values are protective of human health assuming long-term
ingestion of local fish. No chemicals were detected in sediments above conservative health-
based screening values for soil ingestion.
-------
5.1.2 Risk Characterization
Based on a screening comparison and toxicity assessment, the only COCs that exceed risk-
based screening criteria were P AHs at two subsurface soil sampling locations. Although a
few analytical results for some metals in unflltered groundwater samples exceeded the
screening criteria, the exceedances were small and. the metals are not considered
. environmental contaminants in. groundwater at Hamilton Island. Metals are therefore not
considered COCs. The following discussion evaluates the potential health risk associated
with P AHs detected in subsurface soils.
The presence of PAHs at these locations in concentrations somewhat above conservative
screening criteria does not pose a risk to human health for the following reasons:
. PAHs were only detected in two soil samples, therefore the potential for exposure
to concentrations above detection limit is extremely low. Negligible risk is
associated with such limited exposu~ potential. .'
. The concentration of total carcinogenic P AHs is below the MTCA Method A
cleanup level of I mg/kg.,
. The samples in which PARs were detected cqe field duplicate samples. One of
these samples also had TPH detected at 620 mg/kg. TPH in the primary sample
was detected at 100 mg/kg. The P AHs are probably related to the petroleum
residues at that sample location. P AHs were not detected. in either of the
associated primary samples.
In conclusion, the very few chemicals that were detected in isolated samples above
conservative screening criteria are consist~nt with background values (metals) or do not pose
a human health threat because of their low concentrations well within the risk range in
CERCLA, and low detection frequency and exposure potential (pAHs).
-------
5.1.3 Human Health Risk Characterization Summary
Potential future residents and current recreational users are the primary reCeptors at the site.
Residents would be exposed to chemicals detected via ingestion of soil and use of
groundwater from the aquifer. The chief pathway of concern for recreational users would
be exposure to site-related contaminants via fish ingestion.
Concentrations of chemicals detected in the samples from all the media were compared with
- screening-level criteria. The screening-level evaluation provides a conservative (hea1th-
protective) estimate of potential risk because 1) residential exposures to contaminated soil
and groundwater were assumed, 2) conservative toxicity factors were used that are highly
protective of sensitive populations, and 3) low target risk levels were applied in calculating
screening-level criteria. Most detected concentrations were so far below screening-level
criteria that potential human health risk - is negligible. Where sample results exceeded
screening-level criteria, the impact for adverse human health effects was discussed and
shown to be below levels that may warrant remediation based on public health impacts.
5.2
ECOWGICAL RISK ASSESSMENT
The Ecological Risk Assessment (ERA) assessed the potential for impacts to terrestrial and
aquatic receptors from exposure to chemical contaminants from Hamilton Island. The
primary objective of the ecological-risk assessment '"~s to perfonn a screening-ievel analysis
to estimate the potential for adverse effects to plants and animals. The results of the
ecological risk assessment were intended to support management decisions - on whether
remedial action is required for environmental protection.
The screening level approach used in the risk assessment is consistent with EP A guidance
for evaluating ecological risk. Ecological risks are based on the evaluation of data from
analysis of surface water, seepage water, groundwater, sediment,- and surficial soil samples
collected during the RI. Data was compared with appropriate environmental benchmarks for
each media. Benchmarks included EPA Ambient Water Quality Criteria (AWQC) for
protecting freshwater life; dietary toxicity values; available LOEL, NOEL, LD50and -
TIM96 values; and sediment Threshold Value Guideline from sources worldwide.
-------
5.2.1 Exposure Assessment
Potential receptors were identified as those plant and animal species likely to be exposed to
chemicals associated with chemical contaminants from Hamilton Island. The Ecological
Conceptual Site Model (ECSM) developed for this RI included the aquatic habitat in the
Columbia River and Hamilton Creek and the terrestrial habitats on Hamilton Island.
The potentially exposed terrestrial habitats at the Hamilton Island NPL site include
grasslands, shrub/scrub, and wetland areas at seepage points and in the Wildlife Mitigation
Area.. The primary inorganic-media exposure pathways for the terrestrial biota. in the
terrestrial habitats are. from soil and seepage water. The principal terrestrial receptor
categories are small birds and small mammals. These biota may be primarily exposed via
direct contact, incidental ingestion of surface soil, direct ingestion of drinking water, and
direct ingestion of forage or prey containing chemicals. Larger mammals may also be
exposed, but the sum of their exposure is not as comprehensive as that experienced by the
small mammals and birds. .
The potentially exposed aquatic habitats include the Columbia River, Hamilton Creek, and
the Rail Pond. Primary inorganic exposure pathways to the aquatic habitats are associated
. .
with water and sediment. Aquatic biota that may absorb contaminants from water or
sediment may represent a secondary food web exposure pathway to other aquatic consumers
that may eat contaminated prey. The principal aquatic receptor categories are benthic
macroinvertebrates, fish, and amphibians. These biota may be continually exposed to
chemicals through direct contact, direct ingestion, incidental ingestion of water and sediment,
and ingestion of forage or prey. In addition, these habitats support.an abundance of
waterfowl, semi-aquatic mammals (beaver, muskrats, river otter), and aquatic feeding raptors
(osprey and bald eagle). These biota are considered potential receptors. They are
intennittently exposed to water and sediment, but all are primarily aquatic feeders and may
be exposed to chemicals in forage or prey.
5.2.2 Ecological Chemicals of Concern
Potential COCs are waste-related chemicals at Hamilton Island that may pose. a risk to
terrestrial and aquatic receptors who come into contact with them. COCs were identified
-------
through evaluation of RI sampling results for groundwater, surface water, seeps, soils and
sediments.
To identify COCs, maxunum concentrations of chemicals of potential concern were
compared to ecological "benchmarks." Chemicals whose maximum concentrations are below
protective benchmarks are not considered a risk and are not evaluated further. Owing to the
different areas of concern at the Hamilton Island NPL site and the five environmental media,
the COCs at the various areas are expected to vary. Therefore, separate COC determinations
were performed fo: the. media associated. with each potentially exposed habitat.
Surface water, seepage water, and sediment represent potential exposure media to aquatic
biota and to terrestrial biota using aquatic habitats. Seepage of groundwater into the
Columbia River or Hamilton Creek may contribute chemicals to the surface water exposure
medium. Therefore, groundwater data were also screened to identify aquatic COCs. The
analytical results from. samples collected in each habitat were evaluated to identify
preliminary COCs. All the analytical data for samples collected at potential exposure points
were compared to ecological benchmarks. The COC screening was performed for the
following habitats and the potential exposure media specific to each habitat:
. Grasslands: Surface Soil; Seepage Water, Groundwater, Surface Water
. Shrub/Scrub: Surface Soil; Seepage Water; Groundwater; Surface Water
. Wetlands: Seepage Water; Groundwater; Surface Water; Sediment
. Rail Pond: Surface Water; Sediment
. Columbia River: Seepage Water; Groundwater; Surface Water; Sediment
. Hamilton Creek: Seepage Water; Groundwater; Surface Water; Sediment
No COCs were identified by the COC screening.
5.2.3 Ecological Risk Characterization Summary
The purpose of the evaluation was to identify potentially complete exposure pathways and
incomplete exposure pathways. Potential exposure of key receptors is. based on the presence
of all of the six basic components of a complete exposure pathway. If one of the following
-------
components is missing, the pathway is incomplete, exposure cannot occur and there is no
risk to biota:
. Source of chemicals (e.g., Hamilton Island NPL Site)
. Release mechanism (e.g., site runoff)
. Exposure medium (e.g., soil and seepage water)
. Exposure point (e.g., Hamilton Creek surficial sediment)
. Intake or exposure mechanism (c.g., ingestion of seep water)
. Key Receptor Organisms (e.g., osprey)
The ERA identified the presence of important terrestrial and aquatic ecological resources 00 .
Hamilton Island, and in the adjacent Columbia River and Hamilton Creek. Potential
exposure pathways to key receptor organisms were identified for each habitat, but were
shown to be incomplete because no site-related sources were identified. A rigorous chemical
screening was perfonned on the chemicals detected. in all media by comp~g the analytical
results to stringent ecological benchmarks. Several minor ex~~nces of benchmark values
were associated with sampling artifacts and laboratory . ~ntaminants, but these were oot
confmned as COCs. The exposure assessment did not identify any site-related source of
COCs at exposure points for key receptor organisms. Based on these fIndings, the Hamilton
Island NPL site does not currently represent a risk to ecological resources in the local
environment. This conclusion is based on the available data and the assumptions used in
. .
performing the risk assessment.
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6.0
DESCRIPTION OF THE SELECTED REMEDY
EP A has determined that no remedial action is necessary at Hamilton Island to ensure
protection of human health and the environment. This decision is based on the results of the
human health and ecological risk assessments, which determined that conditions at the site
. pose no unacceptable risks to human health or the environment. Additional monitoring and
administrative controls are not necessary. The USACE and EP A, in consultation with
Ecology, have jointly determined that no remedial action is necessary at this site. Ecology
concurs with this determination.
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7.0
IDGHLIGHTS OF COMMUNITY PARTICIPATION
Community involvement was solicited throughout the RIfFS process. A discussion of
community involvement during the RI is presented in Section 7.1 and is followed by a
summary of community participation during selection of the remedy in Section 7.2.
7.1
COMMUl'.TfY RELATIONS DURING THE RI
Local citizens, public officials and public interest groups were interviewed in June and July
1993 to identify potential concerns and public infonnation needs associated with Hamilton
Island. This infonnation was used to develop a Community Relations Plan (CRP) that met
the specific needs of the local communities.
The USACE fmaIized the CRP in September 1993 as part of the management plan for the
Hamilton Island RIlFS. The CRP was designed to promote public awareness of the
investigations and public involvement in the decision-making process. The following
activities were undertaken to address community concerns and public infonnation needs.
A community advisory committee was established in October 1993. This com~ittee met
periodically with the USACE, EPA arid Ecology to discuss the results of the work in
progress, upcoming activities and to provide the committee an opportunity to present their
. concerns. Committee meetings were held at the North Bonneville City Hall on the following
dates: October 21, 1993; April 12, 1994; August 2, 1994; and November 29, 1994.
News releases and infonnation papers were distributed for public review. The news releases
and information papers provided summaries of work in progress, . results to date and
upcoming activities, and also solicited public involvement. The news releases were provided
to loCal radio, television and newspapers (including the Oregonian, Skamania County Pioneer
and Camas Washougal Post Record). About 250 copies of the information papers were
provided to the community and local agencies. The information papers were also placed at
the information repositories.. The distribution schedule of the news releases and information
papers is given in TaQle 3.
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Table 3. Distribution Schedule of News Releases and Information Papers
Date
Docwnent
July 25, 1991 . . . . . . . . . . News Release
August 1991 .,..... Information Paper
January 1993 . . . . . .. Information Paper
January 21, 1993 ....... News Release
July 23. 1993 . . . . . . . . . . News Release
September 1993 ..... Information Paper
September 3, 1993 ...... News Release
October 1993 . . . . . .. Information Paper
October 1, 1993 ....... News Release
February 1994 . . . . .. Information Paper
April 1994 ........ Information Paper
April 15, 1994 . . . . . . . . . News Release
May 12, 1994 ......... News Release
July 1994 ....... .. Information Paper .
July 28. 1994 . . . . . . . . . . News Release .
October 18, 1994 .. . . . . . News Release
November 1994 ..... Information Paper
November 4. 1994 ...... News Release
To promote community awareness of. RIfFS activities, a public display and public
infonnation repositories were established in the fall of 1993. The public display is located
at the North Bonneville City Hall. It has been updated tWice to reflect current project status.
The infonnation repositories contain primary site documents and are placed at the following
six locations:
. City Hall - North Bonneville, Washington
. Community Library - Stevenson, Washington
. Skamania County Courthouse - Stevenson. Washington
. Bonneville Dam Project, Visitor Centers in Oregon and Washington
. Administration Building, Wann Springs Reservation - Wann Springs, Oregon
tn accordance with Section 113 of CERCLA, an Administrative Record was established to
document the basis for the selected remedy. The Administrative Record is available for
public review at North Bonneville City Hall and the USACE Portland District Office. .
-------
7.2
COMM:UNITY RELATIONS TO SUPPORT THE SELECTION OF REMEDY
The public was given the opportunity to participate in the remedy selection process, in
accordance with Sections 113 (k)(2)(B)(i-v) and 117 of CERCLA. The Proposed Plan,
whith summarized ~e RI results and described the preferred alternative, was mailed to
approximately 250 interested parties on November 4, 1994. The USACE distributed a news
release to local media on November 4, 1994 to provide public notice of the distribution of
the Proposed Plan and announce the public meeting and public comment period.
A 30-day public comment period was held from November 7 to December 9, 1994. No
requests for extension were received. A public meeting was held on November 29, 1994.
Oral and written comments were considered by EP A, USACE and Ecology in selecting the
no further action alternative. Responses to written comments, and verbal comments from
. the public meeting are included within the Responsiveness Summary (Section 9.0).
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8.0
DOCUM:ENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for Hamilton Island was released. for public comment on November {
1994. . The Proposed Plan identified No Action as the selected remedy for the site. Public
comments on the Proposed Plan were evaluated at the end of the 3D-day comment period and
.. -,-
it was detennined that no significant changes to the Proposed Plan were necessary.
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9.0
RESPONSIVENESS SUl\1MARY
The public comment period on the Proposed Plan was from November 7 to December 9,
1994. The Proposed Plan was distributed to over 250 agencies and individuals. One set of
written comments was received and is included in Appendix A. . A public meeting was held
on November 29, 1994, to explain the Proposed Plan and solicit public comments. Several
questions were asked during the formal comment period of the public meeting. The
transcript of the public meeting is available in the Administrative Record and information
repositories. This summary' is a response to written and verbal questions and comments
made during the public. comment period.
In this summary, each comment is followed by its corresponding response. Verbal
comments and responses from the public meeting are summarized for clarity. Additional
responses to verbal comments are provided to further clarify responses given in the public.
meeting.
9.1 WRITTEN COMMENTS
FEDERAL AGENCIES
DEPARTMENT OF HEALTH AND HUMAN SERVICES -- PUBIlC HEALTH SERVICE,
Agency for Toxic Substances and Disease Registry .
1. Comment: This letter is in response to the Proposed Plan for HiImillon Island Supeifund
Site. As you are aware, the Agency for Toxic Substances and Disease Registry released. a
public health assessmeru for Hamilton Island Landfill on AugUst 31, 1993. From the
Proposed Plan, we believe that environmental work accomplished siTice that time has
addressed recommendations that we made concerning further characteriZtJtion and analysis
of sedimerus in sun-ounding creeks to address food chain issues.
Response: Comment noted.
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2. Comment: However, we are not aware that one of our concerns has been met. We
recommended that a private well survey to identify private wells in the landfill area be
carried out and that a representative number oj the private wells nearest the kmdfill be
sampled. Although the contaminantsfound-in groundwater are low in concentration, we are
concerned that contaminants could still reach nearby wells. At the time oj the public health
assessment, little information was available to address the likelihood oj contaminants
reaching the private wells. Without sampling information on the private wells or the
placement of monitoring wells between the landfill and the wells, the question remains open.
Response: During the preparation of the Management Plan for the Remedial Investigation,
a survey of all wells in the vicinity of Hamilton Island was perfonned. The . well sUIVey
identified nine private wells in the North Bonneville area that could be used for drinking
water. Two of the wells closest to Hamilton Island were sampled. during the Remedial
Investigati9n. In addition, the golf course inigation well which is the private well closest
to Hamilton Island was sampled. The city of North Bonneville's municipal supply well was
also sampled. All these wells are presumably drawing from the single regional aquifer that
lies beneath Hamilton Island. The gradient in this aquifer fluctuates with the level of water
in the river j but the primary gradient of the aquifer is toward the river. All the private wells
are farther from the. river than Hamilton Island and presumably upgradient from the site,
therefore, it is unlikely that contamination from Hamilton Island, if it existed, would reach
these wells. In addition, four monitoring wells were installed at the :edge of the landfill
between the landfill and private wells.
Results of groundwater sampling indicated very low levels of metals slightly exceeding
. -
MTCA Method B standards in the aquifer beneath the site and in off sit~ wells. Most of
these metals are attributed to sediment in the samples, and not from Hamilton Island. There
were low levels of organic parameters found in water within the fill on site, but these were
not detected in the aquifer beneath the site. Therefore, these res':!lts do not indicate any
significant hydraulic connection between the perched groundwater and the underlying aquifer,
. .
and no route of exposure to people using the aquifer.
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9.2 VERBAL COMMENTS
PRIV ATE CmZEN COM:MENTS PRESENTED AT TIlE PUBUC MEETING
3. Comment: I understand that some of the contamination that wasfound in the knoll area
was to be removed. Has that been done, or is that yet to be done?
Response: When petroleum contamination. was found, an additional investigation was
perfonned at the request of the State of Washington. The excavations where contamination
had been detected were reopened to look for contamination. There was no pervasive
contamination found. There was a lot of d~bris.The intent of the investigation was to
identify and remove extensive contamination. Only a small amount of contaminated soil was
found mixed with a large amount of debris. There was no evidence of pervasive
contamination or contamination that could be easily removed. The USACE and the State of
Washington consulted and decided no further action was necessary.
4. Comment: And so that is closed, and that area is considered safe ~w?
Response: Yes. The material was placed back in the hole because we could not f"md
pervasive contamination.
. Additional Response: The USACE intended to remediate any areas where non-naturally-
occurring chemicals in soils posed a threat to human health and the environment. Two
locations in the knoll area were investigated after the initial results indicated soils with
petroleum hydrocarbons at values above State of Washington standards. Low levels of
petroleum hydrocarboris found in soil during the additional investigation were located in
small isolated areas, and mixed with woody debris. The woody debris may also have caused
interferences that contribute to elevated values in the laboratory analysis. The decision was
made with the State of Washington to place the 107 cubic yards of excav~t~ soil and debris
back into the exploratory trenches because the occurrences. of soils with petroleum
hydrocarbons above Washington State standards were isolated in small areas that could not
be practically remediated.
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5. Comment: There has been some effort at reforestation. Is there any possibility that trees
could be planted on Hatnilton Island? It reaLLy is pretty bald looldng.
Response: There was once a plan to reforest the island. Some attempt was made to plant
trees on it at one time. Most of the trees didn't take hold for a variety of reasons.
Assuming that Hamilton Island is retained in government ownership and is used for wildlife
mitigation purposes, the US ACE and the U.S. Fish and Wildlife Service will discuss what
types of planting might be appropriate to enhance the wildlife mitigation.
6. Comment: /fthat's done, will there be public inpUt into that process or not?
Response: Yes.
Additional Response: The fmal plan for restoration of Hamilton Island will be developed
by the US ACE with the U.S. Fish and Wildlife Service. The USA~!lhopes to use Hamilton
Island as wildlife mitigation land for the Bonneville Second Powerhouse. Some preliminary
plans have been drafted for Hamilton Island, but will be fmalized with USFW and public
input.
7. Comment: What is the main cause that trees and shrubbery don 't grow on the island
there Lila! they do on the rest of the hills out here?
Response: Water is an important factor. The areas that are now well vegetated are
essentially where the. seeps are, where there is water on the surface most of the time.
Possibly, the climate doesn't have enough water to support trees, or at least to get them
started. The trees also may not have been planted or fertilized properly.
8. Comment: The dump area east of town, Parcel 2, we tried there and they didn't stick
either.
Response: Comment noted.
9. Comment: Perhaps it's a lack of nutrients in the soil.
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Response: No topsoil was placed on Hamilton Island or Parcel 2 east of town. A small
topsoil stockpile was placed on the west end of Hamilton Island, but there was no topsoil
placed over the rest of Hamilton Island. So it was basically not a good soil surface.
Additional Response: The primary reason tree plantings did not surVive is because of lack
of water. In most areas water percolates rapidly into the mounded fill and away from plant
roots. Not enough water was initially used to allow the plants to become established. Other
factors include poor nutrition, including possible lack of fertilizer and poor soil conditions.
10. Comment: Thefence will come down in 1995?
Response: Yes. When the Record of Decision is signed and the site is nominated for
removal from the National Priorities List, the fence will be taken down.
11. Comment: You mentioned, more or less, a land trade-off to the optimum town site. .
There is land that isn't in thl! city that was in tM optimum town site. In exchange for
Hamilton Island, whal are some of those areas thai are going to be turned over, maybe, to
the Town of North Bonneville, or how are you going to work thai our?
Response: The question refers to parcels of land that were identified in the initial legislation . .
(Defense Appropriation Act of 1992). They are known as Parcell, which is in the area of
Hamilton Island, Parcel B, which is the northern h?lf of Hamilton Island, and Parcels C, 2,
and H. Under the proposed legislation that was attached to the Water Resources
Development Act of 1994, Hamilton Island, essentially with Parcels 1 and B, would be
retained in government ownership, except for two spikes at the north extremity of Parcel B,
that would be given to the town. Parcel C, Parcel 2, and a ponion of Parcel H could be
given to the town as well. An archeological site on Parcel Hwould be retained by the
government,' but the rest of it would be given to the town.
Additional Response: As a result of legislation passed in the Defense Appropriation Act
of 1992, the USACE is required to sell Parcels 1, 2, B, C, and a portion of H to the city
of North Bonneville. The terms of this legislation have been challenged by the Department
of Justice and portions of the law are not in effect, Replacement legislation was drafted as
a result of negotiations between the city of North Bonneville, the Department of Justice, the
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USACE and Representative Jolene Unsoeld's office. The new legislation would settle all
outstanding claims and differences over land ownership. Under the new legislation that was
attached to the 1994 Water Resources Development Act (WRDA), most of Parcels 1 and
B would remain in government ownership. The other parcels would be deeded to the city
without cost. Because WRnA did not pass in 1994, the legislation must be reintroduced.
Other congressional proponents are being sought for this legislation.
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APPENDIX A
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'~..~....'('. ~'.
{ t
",~,~
DEPARTMENT OF HEALTH & HUMAN SERVICES
Public Health Service
Agency for Toxic Substances
and Disease Registry
Atlanta GA 30333
DEC 0 5 1994
Mr. Norman Tolonen
Project Manager CENPP-PM
Portland District
u.s. Army Corps of Engineers
P.O. Box 2946
Portland, Oregon 97208-2946
Dear Mr. Tolonen:
This letter is in response to the Proposed Plan for Hamilton
Island Superfund Site. As you are aware, the Agency for Toxic
Substances and Disease Registry released a public health
assessment for ,Hamilton Island Landfill on August 31; 1993.
From the Proposed Plan, we believe that environmental work
accomplished since that time has addressed recommendations
,that we made concerning further characterization and analysis
of sediments in surrounding creeks to address foodchain
issues.
However, we are not aware that one of our concerns has been
met. We recommended that a private well survey to identify
private wells in the landfill area be carried out and that a
representative number of the private wells nearest the
landfill be sampled. Although the contaminants found in
groundwater are low in concentration, we are concerned that
contaminants could still reach nearby wells. At the time of
the public health assessment, little information was available
to address the likelihood of contaminants reaching the private
wells. Without sampling information on the private wells or '
the placement of monitoring wells bet~een the landfill and the
wells, the question remains open.
Please let us know if sampling has been carried ,out or if
adequate hydrogeologic information has been obtained to
address the'question. If you have any questions, please call
me or Ms. Diane Jackson at (404)639-6070.
Sincerely yours,
'&-"2 II G---5/.Jff
Gary H. Campbell, Ph.D.
Chief, Army Section
Federal Facilities Assessment
Division of Heaith Assessment
and Consultation
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