EPA Superfund
Record of Decision:
PB98-964606
EPA 541-R98-063
October 1998
Tulalip Landfill
Marysville, WA
9/29/1998
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FINAL
RECORD OF DECISION
TULALIP LANDFILL SUPERFUND SITE
ON-SOURCE AND OFF-SOURCE
REMEDIAL ACTION
MARYSVILLE, WASHINGTON
SEPTEMBER 1998
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 10
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DECLARATION FOR THE RECORD OF DECISION
Site Name and Location
Tulalip Landfill Superfund Site
Marysville, Washington
Statement of Basis and Purpose
This decision document presents the selected final remedial
action for the Tulalip Landfill Superfund Site near Marysville,
Washington, which was chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA),
as amended by the Superfund Amendments and Reauthorization Act
(SARA), and to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). This
decision is based on the administrative record file for the site.
The landfill, including most of the off-source area, is located
within the boundary of the Tulalip Indian Reservation. The
Tulalip Tribes of Washington concur with the selected remedy.
Assessment of the Site
Actual or threatened releases of hazardous substances from
this site, if not addressed by implementing the response action
for the on-source and off-source areas as selected in this ROD,
may present an imminent and substantial endangerment to human
health, welfare, or the environment.
Description of the Selected Remedy
This Record of Decision (ROD) selects the final remedy for
both the on-source and off-source areas of the site.
1. On-source Remedy (from the March 1996 Interim ROD)
The on-source remedy presented in the March 1, 1996, Record
of Decision (ROD) entitled Tulalip Landfill Superfund Site
Interim Remedial Action Marvsville. Washington is the final
remedy for the on-source area. The remedy previously documented
in the March 1996 interim ROD was designed to protect human
health and the environment by containing and preventing contact
with the landfill wastes. Major elements of the final remedy
include:
Capping the landfill in accordance with the Washington State
Minimum Functional Standards (MFS) for landfill closure.
Installing a landfill gas collection system. If necessary/
a gas treatment system will also be installed.
Monitoring the leachate mound within the landfill, the
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perimeter leachate seeps, and landfill gas to ensure the
selected remedy is adequately containing the landfill
wastes.
Restrictions to protect the landfill cap.
Providing for operation and maintenance (O&M) to ensure the
integrity of the cap system.
The selected on-source remedy is expected to stem the migration
of contaminants from the landfill into the surrounding estuary by
minimizing the amount of rain water infiltrating the wastes,
thereby minimizing the generation of new leachate. With the
finalization of this remedy, no further remedial action is
necessary for the on-source area.
The remedial design for the on-source cover system was
completed on May 6, 1998. Construction of the cover system began
on June 18, 1998, and will take approximately 2 years to
complete.
2. Off-source Remedy
The remedy for the off-source area (wetlands) documented in
this ROD was designed to protect human health and the environment
through the continued implementation of institutional controls.
The major element of the off-source remedy selected in this ROD
is to:
Place and maintain an adequate number of signs to prohibit
access to contaminated wetland areas and the consumption of
fish and shellfish from those areas.
Statutory Determinations (Declaration Statement)
The selected on-source and off-source remedial actions are
protective of human healiih and the environment, comply with
Federal, State, and Tribal requirements that are legally
applicable or relevant and appropriate to the remedial action,
and are cost-effective. These remedial actions utilize permanent
solutions and alternative treatment technologies to the maximum
extent practicable for this site. However, the presumptive
remedy approach for municipal landfills selected in the interim
ROD utilizes the remedial approach of containment of wastes
rather than treatment of wastes. Because treatment of the
principal threats at the site was not found to be practicable,
this remedy does not satisfy the statutory preference for
treatment as a principal element of the remedy.
Because this remedial action will result in hazardous
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substances remaining on the site above health-based levels, a .
statutory review will be conducted no less often than every five
years after commencement of remedial action to ensure that the
remedy continues to provide adequate protection of human health
and the environment.
Cfuick Clarke
Regional Administrator
U.S. EPA Region 10
Date
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TABLE OF CONTENTS
1.0 SITE DESCRIPTION 1
1.1 Physical Description of the Landfill (Source Area) . 1
1.2 Off-Source Area (Wetlands) 2
2.0 SITE HISTORY AND ENFORCEMENT ACTIONS 3
2.1 The Tulalip Tribes of Washington 3
2.2 Operation of the Landfill 1964-1979 4
2.3 Operations at the Landfill after 1985 4
2.4 The National Priorities List (NPL) 4
2.5 The Remedial Investigation and Feasibility Study . . 5
2.6 Citizen Suit under Clean Water Act and Resource
Conservation and Recovery Act (RCRA) 5
2.7 Invocation of Dispute Resolution Under the 1993 AOC . 5
2.8 Tulalip Landfill Interim ROD (March 1996) 6
2.9 Allocation Pilot Project 6
2.10 Settlements With Potentially Responsible Parties . . 6
2.11 Comprehensive Baseline Risk Assessment for the
Off-Source Area 7
2.12 Focused Feasibility Study for the Off-source Area . . 7
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 7
4 .0 SCOPE AND ROLE OF ACTION 8
5.0 SITE CHARACTERISTICS 9
5.1 Data and Media Sampled 9
5.2 Release of Contaminants from the Landfill and
Exceedances of Standards in Various Media 10
5.3 Sampling of Off-Site Media to Identify Background
Level Contaminant Concentrations 11
5.4 Summary of the Off-source Area Contamination ... 12
6.0 SUMMARY OF SITE RISK 13
6.1 Overview of Comprehensive Baseline Risk Assessment
for the Off-Source Area 13
6.2 Screening for Contaminants of Potential Concern . . 14
6.3 Exposure Assessment 15
6.4 Toxicity Assessment 17
6.5 Risk Characterization 18
6.6 Uncertainties 20
6.6.1 Key Uncertainties Associated with Calculated
Risks for Human Health 20
6.6.2 Key Uncertainties Associated with the
Calculated Risks to Soil Organisms 21
6.7 Assessment of Site Risk 22
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7.0 OFF-SOURCE AREA REMEDIAL ACTION OBJECTIVES 22
7.1 Off-source Areas of Concern 22
7.2 Remedial Action Objectives 24
7.3 Applicable, Relevant and Appropriate Requirements
(ARARs) 25
8.0 DESCRIPTION OF ALTERNATIVES FOR THE OFF-SOURCE AREA . . 26
8.1 Alternative 1: No Action 26
8.2 Alternative 2: Institutional Controls/
Natural Recovery 27
8.3 Alternative 3: Capping 27
8.4 Alternative 4: Removal and Off-site Disposal ... 29
9.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
FOR THE OFF-SOURCE AREA 31
9.1 Overall Protection of Human Health
and the Environment 32
9.2 Compliance with ARARs 33
9.3 Long-Term Effectiveness and Permanence 35
9.4 Reduction in Toxicity, Mobility, and Volume
Through Treatment 37
9.5 Short-Term Effectiveness 38
9.6 Implementability 39
9.7 Cost 41
9.8 Tribal Acceptance 44
9.9 Community Acceptance 44
9.10 Summary of Comparison Analysis of Alternatives . . 45
10.0 SELECTED REMEDY 45
10.1 The On-source Remedy 45
10.2 The Off-source Remedy 46
11.0 STATUTORY DETERMINATIONS 47
11.1 Protection of Human Health and the Environment . . 47
11.2 Applicable, Relevant and Appropriate Requirements
(ARARs) 48
11.3 Cost-Effectiveness 48
11.4 Utilization of Permanent Solutions and Treatment
Technologies to the Maximum Extent Practicable . . 48
11.5 Preference for Treatment as a Principal Element . . 49
11.6 Five-year Reviews . 49
12.0 Documentation of Significant Changes 49
13.0 RESPONSIVENESS SUMMARY 4°
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1.0 SITE DESCRIPTION
1.1 Physical Description of the Landfill (Source Area)
The Tulalip Landfill Superfund Site (site) consists of a
source area and an off-source area. The Tulalip Landfill source
area occupies approximately 147 acres and is located on North
Ebey Island in the Snohomish River delta. Located within the
bounds of the Tulalip Indian Reservation, the landfill lies
generally between Marysville and Everett, Washington (Figure 1) .
North Ebey Island is bounded to the north by Ebey Slough and to
the south by Steamboat Slough. The island is located in
Snohomish County, Township 30N, Range 5E, Section 32. The
residences closest to the landfill are north of Ebey Slough and
the nearest residence is located approximately 600 feet from the
landfill perimeter.
Prior to landfilling activities, the land on which the
landfill is located consisted of relatively undisturbed
intertidal wetlands. During landfilling operations, barge canals
were cut into the island to allow barges bearing refuse to
transport waste into the landfill. Initially, waste was removed
from the barges and placed directly on top of adjacent wetlands.
During later operations waste was placed into the canals.
The average depth of waste throughout most of the landfill
is about 17 feet. In the old barge canals the fill depth reaches
about 30 feet. Three to four million tons of mixed commercial
and industrial waste were deposited in the landfill during its
period of operation from 1964 to 1979.
The landfill was subsequently closed and a berm was
constructed around most of the perimeter of the landfill. The
surface of the landfill was graded and cover soils were placed
over it. However, insufficient grading of this cover material
resulted in poor drainage and allowed precipitation to pond and
eventually infiltrate the landfill surface. As a result, a mound
of contaminated groundwater (leachate) formed within the
landfill.
Due to the difference in elevation between the leachate
mound and the groundwater level, the weight of the leachate mound
forces leachate down into the groundwater and out of the landfill
into the surrounding wetlands and tidal channels. The majority
of the leachate migrates out of the landfill and into surrounding
waterways. However, a portion of this leachate (5 to 35 percent)
escapes the confines of the landfill and is discharged to the
landfill's surrounding wetlands through a series of seeps, the
majority of which are located along the perimeter of the landfill
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berm.
The volume of discharge from these perimeter seeps is
directly influenced by the amount of precipitation received by
the landfill area. Leachate is discharged in visibly greater
amounts during the wet season due to the increased height of the
leachate mound within the landfill. Conversely/ some of the
perimeter leachate seeps cease to flow entirely during the dry
season due to low levels of precipitation received by the
landfill.
Groundwater beneath the site is brackish and therefore
unusable as a potable water source. Site studies indicate that
contaminated groundwater from the landfill migrates to the
wetlands and sloughs surrounding the site and does not pose a
threat to groundwater drinking water sources located across the
sloughs.
1.2 Off-Source Area (Wetlands)
The off-source area refers to the wetlands and tributaries
adjacent to the berm and bounded by Ebey and Steamboat Sloughs
(Figure 2) . Site access is currently restricted, and the
wetlands adjacent to the west of the site remain relatively
undisturbed by human activity.
A 1995 wetland delineation and functional assessment1 of the
off-source area identified 242 acres of tidal wetlands including
three general types of habitats: high estuarine wetlands; salt
marsh; and mudflats. These wetlands have an important
environmental role in the Snohomish River delta as sources and
sinks .for nutrients, sediment retention areas, and habitat
transition zones, and provide unique ecosystems that support
highly diverse and abundant wildlife species.
One of the most important functions of the wetlands is that
they provide nursery areas for many fish and wildlife species.
Species that live in the wetlands around the landfill include
shorebirds and waterfowl, marsh hawk, coyote, otter, deer,
salmon, cutthroat trout, clams, mussels, and juvenile Dungeness
crab. Both the bald eagle and the northern sea lion are
considered threatened under State and Federal law and have either
been observed in the vicinity of the site or may be expected to
use the habitat areas near the landfill.
1 Western. Draft Tulalip Landfill Wetland Delineation and Functional
Assessment. Prepared for U.S. Environmental Protection Agency.
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The landfill is located within the Puget Sound Estuary, one
of 28 estuaries in the country that have been targeted for
protection and restoration under the National Estuary Program/
which was established by Congress in .1987 as part of the Clean
Water Act. The State of Washington has classified the surface
waters surrounding the site as "Class A" waters of the State,
which are characterized as generally "excellent" waters, where
water quality meets or exceeds the requirements for all, or
substantially all, designated uses.
The tidal mudflats and marsh habitats surrounding the
landfill are natural resources that provide spawning and foraging
areas for wildlife species. The Snohomish River delta is
designated as a Washington Shoreline of Statewide Significance by
the Washington State Department of Ecology, and designated as an
Area of Major Biological Significance for American shad and
English sole by the U.S. Fish and Wildlife Service.
The Tulalip Landfill is situated within this ecologically
valuable ecosystem. Contaminated leachate from the landfill
discharges directly into wetlands that carry on critical habitat
functions. Over the years, human activities have increasingly
led to the destruction and degradation of such wetland areas
within the Snohomish River delta. As such wetland resources
become more scarce, the importance of protecting and preserving
the remaining areas for future generations becomes crucial. The
results of the streamlined baseline Risk Assessment for Interim
Remedial Action (the "Streamlined Risk Assessment") indicate that
the landfill acts as a chronic source of contamination to the
surrounding environment, and that ongoing chemical discharges
from the Tulalip Landfill are resulting in potentially harmful
effects to animals living on and around the landfill.
2.0 SITE HISTORY AND ENFORCEMENT ACTIONS
2.1 The Tulalip Tribes of Washington
The Tulalip Tribes of Washington (the Tribes) is a federally
recognized Indian Tribe organized under Section 16 of the Indian
Reorganization Act of 1934, as amended, 25 U.S.C. § 476. The
lands on which the landfill is located are held by the United
States in trust. In 1936, the Tribes established the Tulalip
Section 17 Corporation, as a federal corporation chartered
pursuant to Section 17 of the Indian Reorganization Act, 25
U.S.C. § 477.
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2.2 Operation of the Landfill 1964-1979
In 1964, the Tulalip Section 17 Corporation leased the
landfill site to the Seattle Disposal Company (SDC) for a 10-year
period. A second lease was executed in 1972. From 1964 to 1979,
SDC operated the landfill under the direction of its general
partners, Josie Razore, John Banchero, and Alphonso Morelli. The
site handled commercial and industrial waste. Between 1964 and
1979, it is reported that approximately three to four million
tons of mixed commercial and industrial waste was deposited in
the landfill.
Because of ongoing environmental problems associated with
the landfill operations, the landfill was closed in 1979. The
closure, fully funded by SDC, required the construction of a
perimeter berm around the landfill waste disposal area, and
placement of cover soils after final grading of the surface.
2.3 Operations at the Landfill after 1985
In 1985, the Tulalip Tribes of Washington sought to place a
thicker soil cap over the landfill to address ongoing leachate
discharges at the site. In order to build a dock for delivery of
materials to the landfill, 'the Tribes receive a dredge and fill
permit pursuant to the Clean Water Act, 33 U.S. C. § 1342, from
the Army Corps of Engineers in March 1986. EPA issued a five-
year National Pollutant Discharge Elimination System ("NPDES")
Permit in February of 1986, which allowed the placement of low
permeability soils as approved by EPA, and required the
collection of leachate.
The NPDES permit was subsequently modified to allow
placement of demolition materials, as approved by EPA, for the
construction of a road network for the capping project. Under
contract with the Tribes, R.W. Rhine, Inc. brought capping
materials from several demolition projects to the site to build
that road network.
In 1990, EPA corresponded with the Tribes regarding the
disposal of materials without EPA approval. In a letter, EPA
recommended that the Tribes cease the voluntary capping effort,
and comply with the NPDES permit requirement to collect leachate.
In 1991, the Tribes wrote EPA that they would not apply to renew
the NPDES permit.
2.4 The National Priorities List (NPL)
On July 29, 1991, EPA proposed adding the Tulalip Landfill
to the National Priorities List (NPL). On April 25, 1995, with
the support of the Governor of the State of Washington, EP7^
published the final rule adding the site to the NPL. In July
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1995, SDC and the University of Washington filed petitions to
challenge the NPL rule in the U.S. Court of Appeals for the
District of Columbia. In June 1996, the Court issued its
decision upholding the listing.
2.5 The Remedial Investigation and Feasibility Study
In August 1993, EPA signed an Administrative Order on
Consent with several Potentially Responsible Parties to conduct a
Remedial Investigation and Feasibility Study. These parties were
Seattle Disposal Company, Marine Disposal, Josie Razore, John
Banchero, Washington Waste Hauling and Recycling, Inc., Rubatino
Refuse Removal, Inc., Monsanto Company, and the Port of Seattle.
Site investigation efforts showed that landfill leachate
leaving the site exceeds water quality criteria and standards for
several contaminants. This leachate flows directly into
sensitive, ecologically valuable wetlands that surround the site,
and into sloughs connected with the Snohomish River and Puget
Sound. The RI documents the presence of hazardous substances in
the soils, sediments, surface water, and groundwater at the site.
2.6 Citizen Suit under Clean Hater Act and Resource Conservation
and Recovery Act (RCRA)
On March 30, 1994, Josie Razore and John Banchero filed suit
against the Tulalip Tribes of Washington, the Tulalip Section 17
Corporation, the Bureau of Indian Affairs (BIA) and Carol
Browner, Administrator of the Environmental Protection Agency
(EPA). The complaint alleged that the TulaLip Tribes of
Washington, the Tulalip Section 17 Corporation, and the BIA were
in violation of their NPDES permit and Section 301(a) of the
Clean Water Act.
On September 23, 1994, the court dismissed the lawsuit,
holding that the court was deprived of jurisdiction pursuant to
CERCLA Section 113(h). The Plaintiffs appealed the dismissal to
the U.S. Court of Appeals for the Ninth Circuit. The plaintiffs
subsequently filed with the court an Appellants Memorandum of
Emergency Motion for Injunction Pending Appeal, which cited
testimony that leachate was discharging from the Tulalip Landfill
site at levels exceeding water quality criteria. The plaintiffs'
emergency motion was denied by the court. On September 19, 1995,
the U.S. Court of Appeals for the Ninth Circuit filed an opinion
upholding dismissal of the lawsuit.
2.7 Invocation of Dispute Resolution Under the 1993 AOC
On February 17, 1995, the Respondents to the 1993
Administrative Order on Consent (AOC) for the conduct of the
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RI/FS invoked dispute resolution under Paragraph 61 of the AOC
with respect to a number of issues. On October 18, 1995, EPA
Region 10's Deputy Regional Administrator issued a final
determination that resolved the issues.
2.8 Tulalip Landfill Interim ROD (March 1996)
In 1996 EPA published the record of decision for the Tulalip
Landfill interim remedial action. The ROD selected capping to
contain and prevent contact with landfill wastes. The selected
remedy is expected to stem the migration of contaminants from the
landfill into the surrounding estuary by minimizing the amount of
rain water infiltrating the wastes, thereby minimizing the
generation of new leachate.
2.9 Allocation Pilot Project
In February 1996, EPA entered into an agreement with 31
potentially responsible parties at the Tulalip Landfill Superfund
site to participate in an allocation process to resolve parties'
responsibility for cleanup costs. Since that time, all but two
of the allocation parties entered into settlement agreements with
the EPA and withdrew from the allocation process. A non-binding
allocation recommendation was issued and one of the parties has
reached agreement on terms for settlement with EPA.
2.10 Settlements With Potentially Responsible Parties
Parties that contributed less than 1.0% documented waste
volume to the site were identified as de minimis parties. Under
three different Administrative Orders on Consent, finalized in
1996, 1997, and 1998, over 200 de minimis potentially responsible
parties (PRPs) have settled and made payments to EPA.
Under a Consent Decree entered by the United States District
Court on March 18, 1998, Waste Management, Inc. agreed to design
the cover system and with proceeds from the various settlements,
construct the cover system. In the same Consent Decree the
Tribes agreed to pay cash toward the settlement and to
participate in the long-term maintenance of the cover system.
Under a second Consent Decree entered by the United States
District Court on March 18, 1998, Seattle Disposal Company agreed
to pay cash towards the construction and maintenance of the cover
system and other project costs.
Under a third Consent Decree, also entered by the United
States District Court on March 18, 1998, most of the remaining
major PRPs agreed to pay cash toward the construction and
maintenance of the cover system.
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2.11 Comprehensive Baseline Risk Assessment for the Off-Source
Area
The Comprehensive Baseline Risk Assessment (CBRA) was
conducted to delineate and quantify potential current and future
risks to human health and the environment in the off-source area
of the Tulalip Landfill Superfund site. The CBRA was conducted
assuming that the interim remedy, a cap over the landfill/ was in
place and fully functioning. The landfill cap is anticipated to
eliminate leachate generation and discharge from the landfill
within a few years following its completion, and thereby reduce
contaminant loadings to the off-source area. The CBRA presents
the results of each step in the risk assessment process including
contaminant identification and screening, exposure assessment,
toxicity assessment, risk characterization, and a discussion of
uncertainties.
2.12 Focused Feasibility Study for the Off-source Area
The focused Feasibility Study2 for the off-source area was
prepared in May 1996. The purpose of this study was to evaluate
potential cleanup alternatives for the off-source area of the
Tulalip Landfill Superfund site.
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
CERCLA requirements for public participation include
releasing the Remedial Investigation and Feasibility Study
(RI/FS) Reports and the Proposed Plan to the public and providing
a public comment period on the Feasibility Study and Proposed
Plan. EPA published notice of the release of the RI/FS and the
Proposed Plan for the on-source area on August 4, 1995. A public
comment period was provided from August 4, 1995 to October 25,
1995. A detailed description of community relations activities
through February 29, 1996, can be found in the interim ROD.
Since that time the following Superfund community relations
activities have been conducted by EPA for the Tulalip Superfund
site:
March 1, 1996 EPA released a fact sheet announcing the
selected remedy described in the March 1,
1996, on-source ROD.
Weston. Tulalip Landfill Off-Source Area Technical Evaluation of Potent'
Remedial Alternatives. Prepared for U.S. Environmental Protection Agency.
May 1998.
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July 9, 1996
August 29, 1997
October 6, 1997
March 26, 1S98
June 19, 1998
August 3, 1998
August 3, 1998
EPA announced the start of a 30-day public
comment period for the first group of de
minimis parties in the Federal Register.
EPA announced the start of a 30-day public
comment period for the second group of de
minimis parties in the Federal Register.
DOJ released a notice in the Federal Register
announcing the start of a 30-day public
comment period on three consent decrees
containing the settlement terms for most of
the major parties.
EPA announced the start of a 30-day public
comment period for the third group of de
minimis parties in the Federal Register.
EPA mailed a fact sheet announcing that the
design for the on-source cover system was
finalized and that construction was
beginning.
EPA released the Proposed Plan for the off-
source area.
Newspaper ad ran in the Everett Herald
announcing the public comment period on the
Proposed Plan and the opportunity for a
public meeting.
September 1, 1998 Comment period on Proposed Plan closed.
Selection of the final remedy is based on the Administrative
Record. There are two copies of the Administrative Record
available for public review. One copy is located at the EPA
Region 10 office at 1200 Sixth Avenue, in Seattle, Washington.
The second copy is located at the Marysville Public Library in
Marysville, Washington.
4 .0 SCOPE AND ROLE OF ACTION
EPA has divided the site remediation into two major phases.
The first phase consists of remediating the 147 acre on-source
area which is the principal risk at this site. The second
of the remediation is to address contamination that may have
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migrated to the surrounding wetlands.
EPA has already selected an interim remedy for the on-source
area as presented in the March 1, 1996, ROD entitled Tulalip
Landfill Superfund Site Interim Remedial Action Marvsville,
Washington. EPA is now incorporating that remedy into this final
ROD. The interim remedy was previously selected in order to
contain contaminant concentrations that exceeded ecological and
human health-based criteria, and in order to stop contaminant
mass loading to the wetlands surrounding the landfill. With the
finalization of this remedy, no further remedial action is
necessary for the on-source area.
This document also presents the additional selected remedial
action for the off-source (wetlands) area of the Tulalip Landfill
Superfund Site, which was chosen in accordance with the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act (SARA), and to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan
(NCP).
5.0 SITE CHARACTERISTICS
5.1 Data and Media Sampled
As part of the Tulalip Landfill Remedial Investigation (RI),
various media including soils, sediment, surface water,
groundwater (zones 1 and 2)J, leachate, fish, and small mammals
were sampled in order to assess contamination associated with the
landfill. In addition, a clam bioassay and mussel
bioaccumulation study were conducted. The RI documents the
presence of hazardous substances in soil/ sediment, surface
water, groundwater (zones 1 and 2), leachate, fish, and small
mammals from the source area, off-source area, and off-site
areas, as well as in clams grown in the laboratory in off-source
and off-site sediment. Table A-l contains a list of contaminants
that were detected in different media. Many of the chemicals are
common across media. For example, seventy chemicals found in
leachate were also found in off-source soil, sediment, and/or
surface water. Twenty-one of these chemicals were also detected
in fish tissue. In addition, 53 chemicals found in leachate were
also found in zone 2 groundwater which exits the landfill into
Zone 1 encompasses the groundwater within the leachate mound located in r.he
refuse layer of the landfill. Zone 2 is the deeper groundwater located o.:.lri'/
the refuse layer.
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the adjacent sloughs. This pattern of shared chemicals among
media suggests that there is a transport mechanism for chemicals
from the landfill (source area) to off-source areas.
5.2 Release of Contaminants from the Landfill and Exceedances of
Standards in Various Media
The primary mechanism by which contaminants are released
from the buried refuse at the Tulalip landfill is leaching. The
RI/FS shows that contaminated groundwater within the landfill
(zone 1) migrates to surface water by way of leachate seeps on
the outside surface of the landfill berm, and deeper groundwater
(zone 2) that surfaces in adjacent sloughs. Leachate seeps,
which generally discharge from the berm surrounding the landfill/
discharge to surrounding soil/sediment and surface water. The
highest concentrations of contaminants in surface soil were
generally reported at the point of leachate seep discharge, and
declined rapidly with distance from the leachate seep discharge.
The results of the Final Tulalip Landfill Risk Assessment
for Interim Remedial Action4 indicate that there are some
exceedances of the site-specific comparison numbers in the
leachate, groundwater, soil, and sediment samples from the site.
These comparison numbers were established based upon human health
and ecological standards, criteria, or risk-based concentrations
that are generally considered to be protective of human health
and the environment.
Of the media screened for human health, there were
exceedances in leachate, off-source soil samples (surface and
subsurface), sediment (surface and subsurface), and surface
water. The highest number of exceedances were found in leachate
and surface soil. The chemicals most frequently exceeding
comparison numbers were arsenic, carcinogenic polynuclear
aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs)
and pesticides. Chemicals measured in leachate seeps (arsenic,
carcinogenic PAHs, PCBs, and pesticides) were at least 10 times
higher than human health criteria (EPA ambient water quality
criteria for fish consumption). Off-source sediment and soil
exceeded criteria for arsenic (EPA Region III risk-based
screening concentrations and Model Toxics Control Act (MTCA)
cleanup standards). Figure 3 identifies sampling locations,
media, and contaminants for the most significant exceedances of
the human health comparison numbers. Generally, all chemicals
that exceeded comparison numbers in soil and sediment samples
Weston. Final Tulalip Landfill Risk Assessment for Interim Remedial
tion. Prepared for U.S. Environmental Protection Agency. August 19'J:
Ac t i o n.
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were also detected in leachate seeping from the landfill surface
and berm.
For the ecological evaluation, contaminants found in surface
soils near six of the nine leachate seeps exceeded sediment
quality standards (SQS). SQS are chemical concentrations in
sediments above which adverse effects may occur to organisms
exposed to the contaminated sediments. These values are
established by the Washington State Department of Ecology for
marine sediments in Puget Sound. Sediment values are considered
appropriate for comparison to soil sample results because many of
the soil sample locations are tidally influenced and tend to be
saturated, and because the parent material of the surface soil in
the off-source area is sediment. Contaminants found in leachate
exceeded marine chronic criteria (MCC) ambient water quality
standards at least once in most of the eleven seeps that were
tested. Groundwater from zones 1 and 2 exceeded MCC for several
contaminants including metals. The highest number of exceedances
of ecological comparison numbers were found in leachate and
surface soil. The chemicals most frequently found in exceedance
of comparison numbers were PAHs, pesticides, and inorganics.
Most of the surface soil samples exceeding criteria were
associated with leachate seeps. Figure 4 identifies sampling
locations, media, and contaminants for the most significant
exceedances of the ecological comparison numbers. Concentrations
of chemicals detected in the high estuarine wetlands (HEW) and
salt marsh soils did not exceed SQS. HEW and salt marsh soil
sample locations are presented in Figure 5.
5.3 Sampling of Off-Site Media to Identify Background Level
Contaminant Concentrations
As part of the RI, various off-site media including soil,
sediment, surface water, fish, and clams grown in off-site
sediment were sampled in an attempt to determine site-specific
background contaminant concentrations. Samples were collected
from the Quilceda Creek, Smith Island, and upstream sampling
areas, which were believed to be relatively uncontaminated.
Analysis of data from these off-site areas revealed a high number
of organic compounds in soil and sediment in addition to the
inorganic contaminants that would be expected to be present. The
organic compounds included various semi-volatile organic
compounds, PAHs, pesticides, and PCBs. The specific source or
sources of the organic contaminants in background samples is not
known. Given the dynamic nature of the estuary environment in
the vicinity of the landfill (e.g., the area is influenced by
tides, flooding, and the Snohomish River), off-site sampling
locations could have been influenced by the Tulalip landfill, or
by other potential sources in the area including non-point
II
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sources (e.g., runoff from residential areas, agricultural land/
and highways) or local point sources (e.g., a sewage treatment
plant and a pulp mill). No attempt was made to distinguish
potential landfill contributions to the background samples from
other potential sources as this activity was beyond the scope of
the site RI.
In addition to the high number of organic compounds detected
in off-site soil and sediment, excessive organism mortality in
bioassays indicated that the off-site samples may not have been
collected from relatively uncontaminated areas. Furthermore, all
clam bioassay samples failed the performance criteria established
in the Washington State Sediment Management Standards.
Therefore, it was determined that the off-site data did not
represent a relatively uncontaminated site-specific background
area, and would not be used to differentiate site-related from
naturally-occurring or ambient levels of contaminants, nor to
screen contaminants of concern in the Comprehensive Baseline Risk
Assessment (CBRA). Instead, Puget Sound regional sediment
reference concentrations5 were used for comparison Oto off-source
sediment concentrations, and Washington State natural soil metals
concentrations6 were used for comparison to off-site soil
concentrations.
5.4 Summary of the Off-source Area Contamination
The primary contaminants in the off-source area are metals
and semivolatile organic compounds (SVOCs) in tidal channel
sediment, and metals in wetland soil. Metals of concern in
sediment consist of arsenic and chromium; and the metals of
greatest concern in soil include aluminum, arsenic, chromium, and
manganese. Other metals are present in sediment and soil but in
lower concentrations and generally below levels of concern to
human health and the environment. The SVOCs of primary concern
in sediment consist of phenol, 4-methylphenol, fluoranthene and
pyrene. Concentrations of concern are contained in Table 1.
U.S. Environmental Protection Agency. Reference Area Performance Standards
for Puget Sound. Puget Sound Estuary Program. EPA/910/9-91/041. September,
1991.
6 Washington State Department of Ecology. Natural Background Soil Metals
Concentrations in Washington State. Toxics Cleanup Program. Publication liO'i
115. October 1994.
12
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Table 1 - Off-source Contaminants of Concern
Contaminant
Sediments
Arsenic
Chromium
Phenol
4 -me thylphenol
Fluoranthene
Pyrene
Soil
Aluminum
Arsenic
Chromium
Manganese
Concentrations (mg/fcg}
8.8
24.9
0.7
0.1
0.1
0.1
-94.4
- 300
-1.4
- 3.0
- 8.1
- 4.1
2,640
3.7
18
146 -
- 33,800
- 47.3
- 174
- 3,620
The concentrations of SVOCs and metals in tidal channel
sediment are generally highest south and west of the landfill.
Concentrations of metals in wetland soil are highest in the areas
surrounding most of the leachate seeps adjacent to the landfill
berm.
6.0 SUMMARY OF SITE RISK
6.1 Overview of Comprehensive Baseline Risk Assessment for the
Off-Source Area
The 1997 Comprehensive Baseline Risk Assessment (CBRA) was
conducted to delineate and quantify potential current and future
risks to human health and the environment in the off-source area
of the Tulalip Landfill Superfund site. An earlier, separate,
streamlined risk assessment, Final Tulalip Landfill Risk
Assessment for Interim Remedial Action, August 1995. evaluated
potential risks from the landfill source area. The CBRA was
conducted assuming that the interim remedy, a cap over the
landfill, as described in the interim 1996 ROD, was in placf .-. J
fully functioning. The landfill cap is anticipated to eliminate
13
-------
leachate generation and discharge from the landfill within a few
years following its completion, and thereby reduce contaminant
loadings to the off-source area. The CBRA presents the results
of each step in the risk assessment process including contaminant
identification and screening/ exposure assessment, toxicity
assessment, risk characterization, and a discussion of
uncertainties. A brief summary of each step is presented below.
6.2 Screening for Contaminants of Potential Concern
Contaminants identified at the site in various off-source
media were evaluated for their potential to cause adverse impacts
to humans and the environment. The media evaluated in the
contaminant screening portion of the human health risk assessment
included purged clams, fish fillets, and surface soil/sediment.
The media evaluated in the contaminant screening portion of the
ecological risk assessment included unpurged clams, whole-body
fish tissue, small mammals, surface and subsurface soil, and
surface and subsurface sediment.
Several criteria were used to screen off-source contaminants
including frequency of detection, the elimination of contaminants
considered essential nutrients, and comparison of site
concentrations to risk-based concentrations. Contaminants that
were detected at least once in a given medium associated with
human health or ecological exposure pathways were retained as
potential human health or ecological contaminants of potential
concern (COPCs) for that medium. Contaminants that were
considered essential nutrients (calcium, iron, magnesium,
potassium, and sodium) and not clearly associated with
quantifiable human or environmental toxicity were eliminated from
further consideration.
All contaminants retained through the above screening steps
that were detected in media associated with ecological exposure
pathways of concern were retained as ecological COPCs. An
additional risk-based screening step was conducted to determine
human health COPCs. All contaminants retained through the above
screening steps that were detected in media associated with human
health exposure pathways of concern were compared to human health
default risk-based concentrations (RBCs). These RBCs were based
on cancer risks of no greater than one in a million and
noncarcinogenic hazard quotients not to exceed 0.1.
EPA Region 3 human health risk-based concentrations tables
were used to develop the RBCs, with the following three
modifications. The residential scenario values were adjusted by
integrating child and 30-year adult exposure for soil and
sediment. The seafood ingestion values were adjusted by applying
14
-------
the Tulalip Tribes' ingestion rates for purged clam tissue. The
adult consumption scenario was adjusted to account for Region 10
site-specific ingestion rates for whole-body sculpin tissue.
Contaminants with maximum detected concentrations below RBCs were
eliminated from further consideration in the human health
evaluation, while contaminants detected at maximum concentrations
above RBCs were retained as human health COPCs. If no RBC was
available for a given contaminant, that contaminant was retained
as a human health COPC. Since the ecological evaluation was
based on a preponderance of evidence approach, which considered a
broader spectrum of receptors and effects than is easily
represented by a single set of risk-based screening criteria, a
risk-based comparison was not conducted to determine ecological
COPCs.
Contaminants selected as human health and ecological COPCs
are presented in Tables A-2 and Table A-3, respectively. In
total, 23 contaminants were identified as COPCs in at least one
of the three media considered for human health (i.e., surface
soil and sediment, fish, and shellfish). Eighty-one (81) non-
nutrient contaminants were identified in the ecological COPCs
screening process.
6.3 Exposure Assessment
The objectives of the exposure assessment were to identify
the appropriate exposure scenarios to be used in the risk
assessment based on current and predicted future land uses,
identify likely pathways of exposure and media contaminated with
COPCs, and calculate daily intakes of COPCs via the identified
exposure pathways.
Current human use of the off-source area is fishing and
hunting. Since the off-source area has been placed in a
"conservation" use category by the Tribes, and no development may
occur in this area with the exception of utility crossings, the
most likely future land use of the off-source area was assumed to
be recreational, including fishing and hunting.
Potential media of concern for human health exposure are
surface soil and sediment, fish, and shellfish. Air, surface
water, leachate, and groundwater were not considered to be media
of concern. Air was not considered a medium of concern because
the off-source area consists of tidally influenced wetlands with
continually saturated soil/sediment which prevents significant
fugitive dust emissions. Also, since volatile organics were not
detected at high concentrations in the off-source area, vapor
emissions were deemed not to be a significant contributor to
exposure. Surface water is not a medium of concern for the off-
15
-------
source area based on the generally low levels of contaminants
detected, and because the landfill cap is expected to eliminate
transfer of contaminants of potential concern from the source to
surface water. Leachate is not a medium of concern for the off-
source area because leachate is expected to be eliminated by the
source area interim containment remedy. Groundwater is not a
medium of concern for the off-source area because it is not
hydraulically connected to aquifers used for drinking water in
the vicinity of the site, and because the interim containment
remedy is expected to eliminate the discharge of contaminated
groundwater to surface water by way of leachate seeps.
Likely human exposure scenarios are consumption of fish and
shellfish, incidental ingestion of surface soil and sediment, and
dermal contact with surface soil and sediment. Recreational
activities including hunting, hiking, and fishing were identified
as ways for adults to ingest or contact surface soils and
sediments. Subsistence consumption of fish and shellfish was
considered for adults and children. Risks related to
recreational fishing and shellfish gathering were considered as
part of the subsistence scenario.
Average and reasonable maximum exposures were considered for
each exposure pathway. The reasonable maximum exposure is
defined as the highest exposure that is reasonably expected to
occur at a site. RME exposure assumptions included the use of
the upper 95th percentile or maximum (whichever was lower)
concentrations of constituents in exposure media, a 6-year
exposure period for child scenarios and a 64-year exposure period
for adult scenarios, and assuming that 39 percent of bottomfish
and 79 percent of shellfish in the diet came from the off-source
area.
Because the Tulalip site is located on tribal lands, and
because some tribal members tend to consume subsistence levels of
fish and shellfish, a tribal subsistence scenario was chosen to
represent the(reasonable maximum exposure at the site. A recent
study of fish consumption habits of the Tulalip tribal members'7
revealed that the tribal members tend to consume a significantly
larger amount of fish and shellfish than members of the general
population. For example, the mean level of bottom fish
consumption for the Tribes was reported to be 2.31 grams/day and
for shellfish was 25.3 grams/day, for a total of 27.6 grams/day.
The mean value for consumption of all fish and shellfish
Toy, K.A., N.L. Polissar, S. Liao, and G.D. Gawne-Mittelstaedt. A Fi.:,\\
Consumption Survey of the Tulalip and Squaxin Island Tribes of the PugeU Soun
Region. Seattle, Washington. October 1996.
16
-------
representative of the general population is 20.1 grams/day. The
upper 95th percentile consumption rates reported for tribal
members were 13.02 and 128 grams/day for bottom fish and
shellfish, respectively, for a total of 141 grams/day. In
contrast, the upper 95th percentile consumption rate of all fish
and shellfish representative of the general population is 63
grams/day. Based on these values, it is clear that any remedial
decisions based on a tribal subsistence fish consumption scenario
will also be protective of individuals who consume recreational
amounts of fish and shellfish.
Terrestrial ecological receptors included the soil-dwelling
community, small mammals, and raptors. Aquatic ecological
receptors included the benthic invertebrate community, fish, and
fish-eating birds. Ecological receptors were evaluated based on
specific organisms including soil microbes, soil invertebrates,
plants, rodents, northern harriers, clams, mussels, amphipods,
Pacific staghorn sculpin, and great blue herons. These receptors
were assumed to be exposed to contaminants in the off-source area
via direct contact with soil and sediment, indirect consumption
of soil and sediment, and through ingestion along the food chain.
6.4 Toxicity Assessment
Risks to human and ecological receptors were measured based
on several criteria. Human health was evaluated with respect to
both cancer and noncancer risks. Cancer risks are expressed as
an individual's chance (e.g., one in a million, or 1 x 10~6) of
developing cancer from off-source exposure to a given contaminant
(e.g., arsenic) or environmental medium (e.g., soil) over an
average lifetime (i.e., 70 years). Noncancer risks are expressed
as a ratio of the amount of a contaminant in off-source media to
which a person is exposed compared to the amount of that
contaminant associated with a minimal likelihood of causing
adverse health effects (i.e., a toxicity value). These ratios
are referred to as hazard quotients. Human health toxicity
values were taken from the Integrated Risk Information System
(IRIS) database and Health Effects Assessment Summary Tables
(HEAST);
Risks to ecological receptors were evaluated using both
toxicity criteria and reference concentrations. Toxicity values
represent levels of contaminants above which adverse effects are
expected to occur; and reference concentrations represent
concentrations measured in similar environmental media or
organisms (e.g., clams) that were not influenced by landfill
contaminants. Due to the lack of acceptable site-specific
background concentrations, reference concentrations were bar,-.-' ->n
alternate studies and literature values representing areas Ih^
17
-------
were not located in the direct vicinity of the off-source area.
Hazard quotients were used to represent the ratio of the amount
of a given contaminant to which that receptor is exposed compared
to the reference or toxicity value associated with that
contaminant (e.g., mercury) and a given receptor (e.g., great
blue heron).
6.5 Risk Characterization
Risks to humans were evaluated for both cancer and noncancer
effects. Cancer risks are expressed as an individual's chance of
developing cancer from exposure to a given contaminant or
environmental medium in the off-source area. EPA considers
excess cancer risks in the range of 10~4 to 10'6 to be generally
acceptable. When excess cancer risks exceed 10~4, EPA will
consider the need for a cleanup action. EPA has further
clarified the extent of the acceptable risk range by stating that
the upper boundary is not a discrete line at 1 x 10~4. Risks
slightly greater than 1 x 10"4 may be considered to be acceptable
if justified based on site-specific conditions, including any
uncertainties regarding the nature and extent of contamination
and associated risks8. Noncancer risks are expressed as hazard
quotients. Hazard quotients are ratios of the actual dose of a
particular contaminant from relevant off-source media compared to
a reference dose for that contaminant. Hazard quotients greater
than 1.0 indicates a potential for noncarcingenic health effects
from site contaminates. As with hazard quotients used to
evaluate human health effects, ecological hazard quotients
greater than 1.0 indicate a potential for concern.
The risks presented below were calculated based on total
concentrations of contaminants in the off-source area (i.e.,
including contamination from all potential sources), and
conservative assumptions about potential exposure to off-source
media. Where potentially unacceptable human health or ecological
risks were identified, the assumptions used to estimate those
risks are further examined in the following section of this
document in order to assess uncertainties associated with the
predicted risk levels. This approach is consistent with EPA
policy on risk management decision making and general remedy
selection principles as described in the National Contingency
Plan.
Tables A-4 and A-5 identify the calculated total
carcinogenic and noncarcinogenic risks for human health for the
U.S. Environmental Protection Agency. Role of the Baseline Risk Assessment
in Superfund Remedy Selection Decisions. OSWER Directive 3355.0-30. April
22, 1991.
18
-------
reasonable maximum exposure (RME) and the average exposure (CTE
or central tendency exposure) scenarios. Human health risks were
driven by consumption of arsenic-contaminated shellfish collected
from the off-source area. For the reasonable maximum exposure
scenario, adult cancer risk from off-source shellfish consumption
was conservatively estimated as 9 x 10"* or nine in ten thousand,
and the adult noncancer hazard index from off-source shellfish
consumption was conservatively estimated to be 3.1. Arsenic was
the largest single contributor to risks from shellfish
consumption, contributing 94 percent of cancer risk and 66
percent of noncancer hazard index. Cancer risk to children
consuming large amounts of seafood (the reasonable maximum
exposure) was calculated to be over an order of magnitude lower
than for the adults, and fell within EPA's acceptable risk range.
The corresponding hazard index was estimated to be 1.0. For the
average exposed subsistence individual (one who consumes less
fish and shellfish than a reasonable maximum), adult and child
carcinogenic risks fell within the acceptable risk range, and
hazard indices fell below 1.0. All cancer, risks (the reasonable
maximum and the average) from incidental ingestion of off-source
surface soil/sediment, dermal contact with off-source surface
soil/sediment, and consumption of fish fell within or below EPA's
cancer risk management range. Similarly, all noncancer hazard
quotients for these exposure pathways were less than 1.0.
Risks were evaluated for off-source aquatic organisms
including fish-eating birds (great blue heron), fish (Pacific
staghorn sculpin), and benthic invertebrates (clams, amphipods,
and mussels). The potential for adverse impacts to the
population size of the fish-eating birds was estimated to be
minimal, with no hazard quotients greater than 1.0. The
potential for adverse impacts to the population size of the fish
community was estimated to be low, with only PCB Aroclor 1254 and
copper having hazard quotients minimally greater than 1.0. Some
potential for adverse impacts to the abundance and diversity of
benthic invertebrates was found. The range of risks was slightly
greater than a hazard quotient of 1.0, and much less than 10.
Contaminants that contributed to the estimated risks were
primarily sernivolatile organics (4-methylphenoi and phenol,
fluoranthene, and pyrene), as well as two inorganics (arsenic and
chromium).
Risks were also evaluated for off-source terrestrial
organisms including raptors (northern harrier),, small mammals
(shrew, vole, and deer mouse), and soil-dwelling organisms
(plants, earthworms, and soil microorganisms). The potential for
adverse impacts to the population size of the raptor community
was estimated to be minimal, with no relevant hazard quotient...
19
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greater than 1.0. The potential for adverse impacts to the
population size of small mammals was estimated to be low, with
only mercury and selenium having hazard quotients minimally
greater than 1.0. Some potential for adverse impacts to the
abundance and diversity of soil-dwelling organisms was found.
Hazard quotients were elevated only marginally (i.e., by less
than an order of magnitude) for two organic contaminants,
acenaphthene and fluorene; but were substantially elevated (i.e.,
by more than an order of magnitude), for a few inorganic
contaminants including aluminum, chromium, and vanadium.
6.6 Uncertainties
The CBRA includes detailed discussions of the uncertainties
associated with the estimation of exposures and risks for human
health and ecological organisms. Uncertainties related to
general site conditions, sampling and analysis, and fate and
transport parameters are also discussed in the CBRA.
6.6.1 Key Uncertainties Associated with Calculated Risks for
Human Health
For human health, the results of the CBRA indicate that only
one exposure scenario (subsistence level ingestion of shellfish
from the off-source area) exceeds the acceptable risk range for
carcinogens and the hazard index for noncarcinogens. Other
pathways (incidental soil/sediment ingestion and fish ingestion),
using conservative estimates, were not determined to present
unacceptable risks. The key uncertainties associated with the
calculated risks from the shellfish ingestion scenario are as
follows:
Overestimation of fish and shellfish consumption and
availability Risk assessments were based on an adult
subsistence level of consumption and assumed 100 percent of
this subsistence diet was collected from the off-source
area. This scenario is unlikely.
Use of a single shellfish species to represent all shellfish
consumed from the off-source area The use of clams to
represent all shellfish species consumed from the off-source
area may have resulted in further overestimation of risks.
Clams, which reside in sediment, are likely to contain
higher concentrations of contaminants than other shellfish
present in the off-source area. A variety of other edible
shellfish (including crabs, mussels and soft-shell clams)
are present in the off-source area and likely have
significantly lower contaminant concentrations.
Percentage of inorganic arsenic in seafood - The CBRA
20
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assumed that 10 percent of arsenic contained within edible
fish and shellfish was of the toxic, inorganic form.
Another study* indicates that actual inorganic arsenic
concentrations likely range from 0 to 2.9 percent. The
assumption of 10 percent inorganic arsenic in shellfish
could contribute to a risk overestimation factor of as much
as 3 times the actual risk present in the off-source area.
Regional sediment arsenic levels similar to off-source area
arsenic levels An attempt to gather site-specific
background concentrations was unsuccessful during the
remedial investigation. As a result, regional background
arsenic concentrations were used as a comparison. The
results of this comparison demonstrate that- although tissue
arsenic concentrations of clams grown in off-source sediment
tend to be slightly higher than those measured in other
Puget Sound locations, they are similar to ranges found
within regional shellfish tissue background concentrations.
While risk estimates in general are affected by many
uncertainties which could either increase or decrease estimated
risk, EPA notes that the key uncertainties associated with the
shellfish ingestion scenario when considered cumulatively have
the effect of lowering estimated risks by as much as a full order
of magnitude.
6.6.2 Key Uncertainties Associated with the Calculated Risks to
Soil Organisms
The primary uncertainty associated with the ecological risk
estimates is the chemical form or bioavailability of the
contaminants. In the CBRA, it was assumed that contaminant
concentrations were 100% bioavailabie. This is highly doubtful,
particularly for inorganics, since contaminants in the ambient
environment are quite frequently bound as complexes that reduce
their overall bioavailability. Therefore, risks are most likely
overestimated.
A secondary set of uncertainties relates to the toxicity
criteria used. For the soil evaluation, toxicity criteria were
gathered from the Oak Ridge National Laboratory''0 database, which
Chew, C.M. Toxicity and Exposure Concerns Related to Arsenic in Seafood:
An Arsenic Literature Review of Risk assessments. Prepared for Region X EPA
Risk Evaluation Unit. March, 1996.
10 Oak Ridge National Laboratory. Screening Benchmarks for Ecological Risk
Assessment. Version 1.5. Prepared by Environmental Sciences and Health
Sciences Research Divisions, Oak Ridge Tennessee, for U.S. Department oL
Energy, Washington, DC. 1996.
21
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was developed primarily for screening purposes. The effects
associated with the toxicity levels include decreased growth and
decreased activity, both of which may or may not be indicative of
serious deleterious effects to species populations and/or the
overall ecosystem at the site (i.e., these are fairly
conservative values based on the not-so-severe nature of effects
used). Conversely, these toxicity criteria are based on a 20%
observed reduction in effects, not a "no effects" level.
Therefore, it is possible that they may not be conservative
enough.
Finally, a comparison of regional background concentrations
of the inorganic contaminants11 does not indicate greatly
elevated levels in off-source soil. Based on this comparison, it
is likely that a significant portion of risks to the soil-
dwelling community from inorganic contaminants may be
attributable to natural background levels.
6.7 Assessment of Site Risk
Actual or threatened releases of hazardous substances from
this site, if not addressed by implementing the response action
for the on-source and off-source areas as selected in this ROD,
may"present an imminent or substantial endangerment to human
health, welfare, or the environment.
7.0 OFF-SOURCE AREA REMEDIAL ACTION OBJECTIVES
7.1 Off-source Areas of Concern
The CBRA identified consumption of fish and shellfish as the
primary pathway associated with potential risks to humans. A
tribal subsistence scenario was assumed in the CBRA and used to
determine average and reasonable maximum exposure limits (RME)
based on the possibility of some tribal members consuming
subsistence levels of the fish and shellfish contained in the
off-source area. Only the RME exposure scenario exceeded the
acceptable risk range. Potential risks to adults who consume
average subsistence levels and to children who consume
subsistence levels of seafood were below levels of concern. The
primary contaminant of concern related to human consumption of
fish/shellfish was arsenic. Other metals, pesticides, and PCBs
also contributed to these risks.
A background evaluation was conducted which compared
Washington State Department of Ecology. Natural Background Soil Mel.als
Concentrations in Washington State. Toxics Cleanup Program. Publication »94-
115. October 1994.
22
-------
concentrations of sediment contaminants in the off-source area
with existing regional soil and sediment background
concentrations. Contaminants found to exceed background
concentrations include aluminum, arsenic, chromium, and
manganese. Most of the exceedances were found to be marginally
above the background concentrations except for arsenic and, to a
lesser degree, chromium. It is important to note that even
regional sediment background concentrations of arsenic indicate
potential risks to human health, and regional soil background
concentrations of chromium indicate potential risks to
terrestrial ecological receptors.
Off-source areas with soil and sediment background
exceedance ratios greater than or equal to 1.20 (20 percent above
background) were evaluated for potential remedial action.
Focusing on areas with metal concentrations more than 20 percent
over background would maximize cleanup of areas of the greatest
potential harm to human health and the environment.
Although fish tissue data suggest the potential for human
health risks from ingestion of pesticides and PCBs in fish, these
compounds were detected in few off-source sediment locations and,
where found, they were detected at low concentrations.
Therefore, EPA has determined that remediation of sediment for
pesticides and PCBs is not warranted. It is possible that
because fish may also forage off site, they may have accumulated
some of these contaminants from off-site locations.
Off-source sediment exceeds Washington State Sediment
Management Standards (SMS) Sediment Quality Standard (SQS) and
Cleanup Screening Level (CSL) concentrations for some SVOCs and
metals. Phenol generally exceeded only SQS and not CSL
concentrations. Since phenol was generally detected below SQS
and since it readily degrades and attenuates in the aquatic
environment, it was not considered for cleanup. Sediment CSL
exceedances were associated with 4-methylphenol, fluoranthene,
pyrene, chromium and arsenic. The off-source areas with CSL
exceedances for these contaminants were considered in determining
cleanup areas based on potential ecological impacts.
Based on the conclusions in the risk assessment, Table 2
shows which stations are associated with areas that did undergo
remedial alternative evaluation and the likely receptors and
contaminants.
23
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Table 2 - Remedial Alternative Evaluation Areas
: : Sample
':':'Station
K*c«pcor/FatJiway
j '
contaminant i , rr * **} SO-11 - .
SG-13
SG-15
SC-18
SG-20
SG-21
SG-24
. 80-25
' ' SG-32
Sh*llfi*h Consvnnption
B«nthos Contact
Banthos Contact
B«nthoa Contact
Shellfish Consumption
Benthos Contact
Shellfish Consumption
Benthos Contact
Benthos Contact
Shellfish Consumption
Shellfish Consumption
Benthos Contact
Arsenic
4 -Methylphenol
4 -Methylphenol
Fluoranthene ,
Pyrene
Arsenic
Arsenic
4 -Methylphenol
4 -Methylphenol
Arsenic
Arsenic
4 -Methylphenol
Background
CLS
CLS
CLS
Background ,
CLS
Background
CLS
CLS
Background
Background
CLS
'-0"i't <-' ' < ' Soil - - i ''
S««p 1
y^r*;-2 /
,r. S««p 3
x V f '' t
^B+*p,A' .;.
^>^?x^V'' »
Xii$Wt';§ !'N
:£$9*& '£,-'"
*?<*. ./ -
, 84MP 7
S««p 8
Terrestrial
Ecological
Terrestrial
Ecological
Terrestrial
Ecological
Terrestrial
Ecological
Terrestrial
Ecological
Terrestrial
Ecological
Terrestrial
Ecological
Terrestrial
Ecological
Chromium, Arsenic
Chromium, Arsenic
Chromium
Chromium
Chromium, Arsenic
Chromium, Arsenic
Chromium, Arsenic
Chromium
Background
Background
Background
Background
Background
Background
Background
Background
7.2 Remedial Action Objectives
Remedial action objectives (RAOs) are medium-specific or
operable-unit-specific goals to protect human health and the
environment. RAOs specify the exposure routes and receptors,
contaminants of concern, and an environmental or human health
remediation objective.
Elevated site risks are associated with human ingestion of
shellfish living in sediment around the landfill. Ecological
risks are associated with sediment in some tidal channels around
24
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the landfill and with wetland soil adjacent to most of the
leachate seeps on the landfill berm. Since even in their current
state the wetlands surrounding the landfill play an important
ecological role in the Snohomish River delta and Puget Sound,
goals established to address chemical contaminants must be
balanced against physical impacts to the wetlands associated with
potential remedial actions in the off-source area. An executive
order requires that federal agencies avoid adversely impacting
wetlands wherever possible, minimize wetland destruction, and
preserve the value of wetlands.
The RAOs for the Tulalip Landfill off-source area are:
Minimize human consumption of fish/shellfish which
contain contaminants that result in an elevated
potential risk.
Minimize potential for arsenic-contaminated soil
surrounding the leachate seeps from acting as a
continuing source of arsenic in the off-source
sediment.
Minimize potential for benthic organisms to contact
sediment which exceeds CSLs without physically
destroying wetland habitats.
Minimize potential for terrestrial ecological receptors
to contact soil containing arsenic/ manganese/ and
chromium at concentrations significantly greater than
background concentrations.
Minimize physical impacts to and loss of off-source
wetlands.
7.3 Applicable, Relevant and Appropriate Requirements (ARARs)
The Washington Sediment Management Standards (WA 173-204)
are ARARs for the off-source remedial action because they
establish numerical values for chemical constituents in
sediments, and Executive Order 11990 is a to-be-considered
(TBC)requirement because it requires that federal agencies avoid
adversely impacting wetlands wherever possible and preserve the
value of wetlands.
Washington Sediment Management Standards (MAC 173-204) are
relevant and appropriate requirements to the off-source remedial
action. The Washington Sediment Management Standards establish
numerical values for chemical constituents in sediments. Thorpe
standards are not legally applicable, because the site is located
25
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on tribal lands where state requirements are not enforceable.
However, the standards are relevant and appropriate because their
purpose is to provide standards for determining acceptable
levels of contaminants in sediments. The selected remedial
action for the off-source area complies with these standards
because, following source control/ natural recovery will reduce
the concentrations of organics and inorganics.
Executive Order 11990 ("Protection of Wetlands"), as
implemented bv 40 C.F.R. Part 6, Appendix A is a TBC for the off-
source remedial action. Within and adjacent to wetlands,
Executive Order 11990 directs actions to be performed so as to
minimize the destruction, loss, or degradation of wetlands. The
off-source area of the site consists of ecologically productive
wetlands, and Executive Order 11990 is, therefore, to be
considered in selecting a remedy for the off-source area that
results in minimal destruction of, or impact to, these valuable
wetlands. Since the Tulalip Landfill is located on tribal
property/ state regulatory requirements do not necessarily apply
to work performed in this location. However, compliance with the
federal regulations and the substantive portions of state
regulations is prudent to protect the environment.
8.0 DESCRIPTION OF ALTERNATIVES FOR THE OFF-SOURCE AREA
8.1 Alternative 1: No Action
The no-action option involves no active remedial efforts and
would not reduce the mobility, toxicity, or volume of the
contamination contained in the off-source area. Following the
implementation of the interim remedial action landfill cap, the
off-source area would remain in its existing condition. No
effort would be made to restrict access to the off-source area
and any potential for human and ecological exposure to
contamination would remain.
Existing contamination would remain in place. Following
source control, organic contaminants would be left to degrade
through natural processes such as dilution, dispersion, and
biodegradation. Metals exceedances in the wetlands could be
expected to recover over time through natural recovery
(sedimentation) since the off-source area is generally
depositional. Any activities occurring on or near the
contaminant areas would be allowed to continue without
restriction. Periodic monitoring, which is already required by
the interim remedial action ROD, could be used to ensure
contaminant levels in the off-source area will not pose a threat
to human health or the environment.
26
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The no-action option is typically used as a baseline
comparison for the evaluation of additional remedial
technologies. No action may be appropriate when risks posed by
contamination are considered insignificant. No action may also
be viable when alternative remedial technologies are anticipated
to cause a disproportionate amount of environmental damage in
comparison to the risks posed by the presence of contamination.
8.2 Alternative 2: Institutional Controls/Natural Recovery
This alternative consists of maintaining existing signs, and
as necessary, posting new signs along the perimeter of the
sloughs and landfill warning of the potential risk from
harvesting and eating fish and shellfish. Signs would be located
approximately every 300-600 feet along Steamboat Slough and Ebey
Slough. Additional signage as necessary would be posted by the
Tribes or a potentially responsible party, in and around the off-
source area by the use of manual labor, boats, and rafts.
Following source control, natural recovery would reduce the
concentrations of organics and inorganics. The organics present
are predominantly phenols and phenolic compounds. These
materials are water soluble and highly biodegradable. The
organic concentrations are relatively low in concentration and
would degrade over time. The metals in the sediments are
expected to recover to background concentrations over time
through the deposition of clean sediment on their surface during
periodic flooding events in the sloughs.
Inspection and maintenance of the signs would be performed
by the Tulalip Tribes to ensure that they were still in place and
readable. The Tribes would also be responsible for enforcement
of this institutional control. Periodic monitoring of the
impacted sediment and seep soil is already required by the
interim remedial action ROD. Monitoring would ensure the
contaminants were attenuating and not migrating or increasing in
concentrations.
8.3 Alternative 3: Capping
This alternative would consist of covering the impacted
sediment areas shown in Figure 6 with a nominal 1 foot of clean
fine-grained fill. Contaminated seep soil would be capped with 2
feet of clean fill after removing the top 2 feet of contaminated
soil. Removal of the top 2 feet would be performed to minimize
the erosion potential of the cap material. Removal to cleanup
criteria is not considered feasible since the soil is most likely
contaminated from leachate and is anticipated to extend to
considerable depth.
27
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Table 3 shows the estimated fill volumes that would be
required to cap the tidal channel sediments. Table 4 shows the
estimated cut and fill volumes for capping the seep area soil.
To provide access to these areas, a perimeter road would need to
be constructed around the base of the landfill to provide access
to the areas requiring remediation as the landfill berm cover has
not been designed to withstand equipment traffic. Floating
equipment (e.g./ barges) would not be practical due to the low
frequency with which the wetlands are submerged.
Table 3 - Sediment Capping Areas and Estimated Volumes
Station
SG-06
SG-10 til
. ~ SG-13
&'+ SG-15 -
SG-18
SG-20 t21
, 86-24
.., SG-25
::; SG-32
Liengtn
(ft)
250
400
200
100
200
1,200
400
200
150
wxcitn
fft)
30
20
20
30
20
30
30
10
50
FaJU. OepUl;:
(ft)'' '"Sii
1
1
1
1
1
1
1
1
1
Total
jFiJlJL jVoiume
'^W.;YV;1 ''- :"
278
296
148
111
148
1,333
444
74
278
3.110
Table 4 - Estimated Seep Area Soil Cut and Fill Volumes
-Seep Area
r '''>to/<*> *
i
2
3
4
5
6
.:.-:' 7
8
l«angtti
Cft)
140
200
70
40
120
200
200
30
Tota!
Widtn -
(ft)
90
150
60
40
60
180
170
30
Removal
Depth
fffc>
2
2
2
2
2
2
2
2
Rentove/FiLL
Volume
-------
may also be necessary to lay geotextile material prior to road
construction to provide additional support, for the road base.
Once the road was constructed, the cap material would be
off-loaded from mix trucks and discharged into the inlet of a mud
pump. Rubber pipelines would be placed manually over swamp mats
or similar devices from the slurry area out into the wetland,
where the clean mud slurry would be placed over the existing
contaminated sediments. Equipment would need to be moved and
relocated to eight different locations to reach the contaminated
areas. Final leveling of the sediment would be performed
manually.
Silt fences and oil booms would be installed downstream of
the placement area in the tidal channels and sloughs to trap
sediment and minimize sediment loss and contain any floating
organic contaminants which may be released during remediation.
Seep area soil would be excavated to a depth of 2 feet. The
soil would be loaded into trucks for proper off-site disposal at
a landfill. Clean soil would be brought to the site via dump
trucks and used to fill the excavation areas.
8.4 Alternative 4: Removal and Off-site Disposal
This alternative consists of removing the contaminated
sediment from the tidal channels. To minimize the release of
sediments to the wetlands, a vortex dredging pump would be used
to remove the contaminated sediment. The dredging pump would
need to be supported on the end of a tracked excavator or small
crane. The sediment dredging areas and volumes are listed in
Table 5. It was assumed that a 1-foot dredge depth would be
adequate to remove the impacted sediment.
Table 5 - Sediment Dredging Areas and Estimated Volumes
Station
SG-06
SG-10 611
SG-13
SG-15
SG-18
SG-20 £21
SG-24
SG-25
SG-32
JLengtft
fftt
250
400
200
100
200
1,200
400
200
150
Wiattt.: £.;:«;
(ft)«w
30
20
20
30
20
30
30
10
50
FiAJi oeptn ;
,--. :-.::. - . . ' . ... " . . . :-:.-.
mm^(fty^^»
i
i
i
i
i
i
i
i
i
Total
FZH voJLurae
ipNffc'IWv-lp
278
296
148
111
148
1,333
444
74
278
3.110
29
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Seep area soil would be removed to a depth of 2 feet and
capped with clean soil as in Alternative 3. Removal to cleanup
criteria is not considered feasible since the soil is most likely
contaminated from leachate and is anticipated to extend to
considerable depth.
A road system would be constructed to provide access to the
seep area soil as well as the tidal channel sediment. Roads
would need to be constructed next to the tidal channels to
provide access for the dredging equipment. The roads would be
constructed of 3 feet of import granular fill. The perimeter
road would be 20 feet wide and the tidal channel access roads
would be approximately 10 feet wide. Roads would need to be
constructed out to each of the nine different areas. The total
length of road that would need to be constructed is approximately
8/200 feet of perimeter road and 3/600 feet of access road along
the tidal channels.
The contaminated sediment would be dredged from the estuary
where it would be pumped to a pond constructed at the foot of the
landfill. Booster pumps would be required to pump the sediment
to the pond. The pond would be lined with a geotextile and have
a capacity of approximately 1/200/000 gallons. The pond would be
approximately 200 feet wide by 200 feet long by 4 feet deep.
This pond size would allow for an equal quantity of water as
sediment to be dredged (i.e./ 1:1 sediment to water ratio).
The dredged sediment would be allowed to dewater and then be
decanted. The remaining soft sediment would need to be
stabilized with flyash to eliminate separable water. The
stabilized material would then be loaded into trucks for proper
disposal. It is anticipated that approximately 50 percent by
weight of flyash to sediment would be needed to absorb the
entrained water in the sediment.
This alternative would result in the dredging of
approximately 3,100 cubic yards of sediment. Stabilization would
create a total of 4,700 cubic yards, which may require off-site
disposal. It is estimated that approximately 600,000 gallons of
water would require treatment as a result of sediment dewatering.
The water would be filtered and passed through a carbon treatment
system to remove any dissolved organic compounds. Treated water
would be discharged back into the slough.
Seep area soil capping would require removal of
approximately 9,400 cubic yards of soil. The remaining pits
would be capped with an equal quantity of clean fill.
30
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Monitoring would be required in this alternative since
contaminated soil would be left in place in the seep areas.
9.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
FOR THE OFF-SOURCE AREA
To evaluate and select a preferred alternative for the
Tulalip Landfill Superfund site off-source area, EPA used the
criteria below. Comments on the proposed plan were used to
evaluate the preferred alternative regarding the last two
criteria: tribal acceptance and community acceptance.
1) Overall protection of human health and the environment
addresses whether a remedy provides adequate protection and
describes how risks posed through each pathway are
eliminated, reduced, or controlled through treatment,
engineering controls, or institutional controls.
2) Compliance vith applicable or relevant and appropriate
requirements (ARARs) addresses whether a remedy will meet
all of the ARARs of other Federal and State environmental
laws and/or justifies a waiver.
3) Long-term effectiveness and permanence refers to expected
residual risk and the ability of the remedy to maintain
reliable protection of human health and the environment over
time, once cleanup goals have been met.
4) Reduction of toxicity, mobility, or volume through treatment
is the anticipated performance of the treatment technologies
a remedy may employ.
5) Short-term effectiveness addresses the period of time needed
to achieve protection and any adverse impacts on human
health and the environment that may be posed during the
construction and implementation period, until cleanup coals
are achieved.
6) Implementability is the technical and administrative
feasibility of a remedy, including the availability of
materials and services needed to implement a particular
option.
7) Cost includes estimated capital and O&M cost, as well as
31
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present-worth cost.
8) Tribal acceptance includes consideration of the Tribes'
comments on the Proposed Plan and whether they support EPA's
preferred alternative.
9) Community acceptance summarizes the public's general
response to the alternatives described in the Proposed Plan
and RI/FS Report.
9.1 Overall Protection of Human Health and the Environment
9.1.1 Alternative 1: No-Action
The no-action alternative is not protective of human health
and the environment. Fishing activities and the collection of
shellfish would be allowed to continue without restriction.
Potential impacts to human health may occur through the ingestion
of fish and shellfish containing elevated levels of arsenic
within the off-source area. Environmental impacts may occur
through sediment benthos and soil-dwelling organism exposure to
elevated levels of organics and metals. Although contaminant
reduction will occur through source control and natural
attenuation processes over time, the no-action alternative does
not actively reduce the immediate human health risks posed by
elevated contaminant levels in the off-source area.
9.1.2 Alternative 2: Institutional Controls
Alternative 2 provides protection of human health by warning
potentially affected parties of the potential hazards presented
by the off-source area. The warning of potentially affected
parties is accomplished through the placement of signs in and
around the perimeter of the off-source area. Similar to the no-
action alternative, Alternative 2 does not actively reduce the
risks posed by elevated contaminant levels in the off-source
area.
Protection of the environment is limited to natural
processes that can be expected to occur in the off-source area
over time following source control. These processes may degrade
the presence of organics through dilution, dispersion, and
natural attenuation. Inorganic contaminants in sediment (such as
arsenic) can be expected to decrease in concentration after
source control due to sedimentation processes.
9.1.3 Alternative 3: Capping
Alternative 3 would provide protection of human health unu
32
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the environment through the containment of contamination found in
the off-source area. Potential risks to human health would be
mitigated by lessening the potential for human consumption of
contaminated seafood. Environmental risks would be reduced by
isolating contaminants from exposure to benthic organisms and
many local terrestrial wildlife species. Contaminant exposure to
soil-dwelling organisms would be reduced if this alternative were
implemented by providing them uncontaminated surface soil and
sediment.
Implementation of this alternative could be expected to
significantly damage the wetland areas that need to be traversed
to place pipelines and equipment. Large volumes of fill for the
access road/ and swamp mats or similar devices for the pipelines,
would need to be placed over the soft wetland soil. These
actions would tend to destroy and damage plant and wildlife
habitat.
9.1.4 Alternative 4: Removal
Alternative 4 provides protection of human health and the
environment. The removal of potentially hazardous off-source
contaminant areas would decrease the incremental risks from human
consumption of impacted seafood and from environmental exposure
to contamination within the off-source area. Seep soil and
sediments exceeding cleanup goals would be removed and properly
transported off site.
Significant damage to the wetlands could be expected to
occur similar to Alternative 3 except to a larger degree. This
is due to the need to construct additional access roads into the
tidal channels to allow access for dredging equipment.
9.1.5 Comparison of Alternatives
As discussed above, Alternatives 2, 3, and 4 are protective
of human health and the environment. Alternative 1 is not
protective of human health because it would allow fishing and
collection of shellfish from contaminated areas.
9.2 Compliance with ARARs
9.2.1 Alternative 1: No-Action
This alternative would comply with all ARARs, including, in
the long-term following source control, the guidelines in the
Washington State Sediment Management Standards (SMS).
9.2.2 Alternative 2: Institutional Controls
This alternative would comply with Executive Order 11990
33
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since damage to the wetlands and impact to water quality would be
minimal. Compliance with the SMS in the long term would be met
following source control and natural attenuation.
9.2.3 Alternative 3: Capping
Filling portions of the wetlands with the access road and
cap material does not meet the intent of Executive Order 11990
"Protection of Wetlands," which discourages filling or damaging
wetlands.
Capping would meet the requirements of the SMS regarding
isolating the contaminants of concern from the environment.
9.2.4 Alternative 4: Removal
This alternative does not meet ARARs. Executive Order 11990
"Protection of Wetlands" discourages damaging and destruction of
wetlands. Construction of access roads into the wetland to make
access for dredging equipment would cause significant damage
which/ over time/ may disappear.
This alternative would remove the contaminants above SMS
guidelines and would thereby meet the requirements of this ARAR.
Separable water from sediment dewatering would be treated to
meet ambient water quality criteria (AWQC) and Clean Water Act
(CWA) discharge concentrations in addition to other likely
National Pollutant Discharge Elimination System (NPDES)
requirements regarding dissolved oxygen/ oil and grease, and
turbidity. Treated water would be discharged back into the
sloughs.
9.2.5 Comparison of Alternatives
Implementing a remedy that requires intrusive work in the
wetlands is anticipated to cause damage to the wetlands. An
alternative such as capping would probably have the least impact.
Alternatives 3 and 4, which require heavy equipment to move into
the wetlands, would cause significant damage. These intrusive
types of alternatives would not meet the intent of ARARs designed
to protect these sensitive areas. Executive Order 1199012
requires that federal agencies avoid adversely impacting wetlands
wherever possible, minimize wetlands destruction, and preserve
the value of wetlands. Alternatives 1 and 2 would meet all of
the requirements of ARARs.
12 Protection of Wetlands, Executive Order 11990 (40CFR Part 6, Appendix A)
34
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9.3 Long-Term Effectiveness and Permanence
9.3.1 Alternative 1: No-Action
The no-action alternative does not actively remove
contaminated soil or sediments from the off-source area. The
risks that remain following the "implementation" of this
alternative are equivalent to the risks currently present in the
off-source area, although eventually interim remedy source
control and natural attenuation are expected to reduce risks to
background levels.
The no-action alternative does not provide any type of
warning to the potentially affected users of the off-source area.
These potentially affected parties include the members of the
general public and the Tulalip Tribe members who utilize the off-
source area for subsistence fishing and shellfish collection.
Therefore, even though source control will minimize future
releases of contaminants from the landfill, the long-term
effectiveness and permanence of this remedy in protecting human
health may be low because even regional background clam tissue
and sediment concentrations lead.to unacceptable potential risks
for subsistence seafood consumers using the conservative
assumptions of the Tulalip Landfill off-source area CBRA.
Long-term protectiveness of the environment would be
considered to be moderately effective since natural attenuation
is anticipated to reduce the contaminant concentrations over
time.
9.3.2 Alternative 2: Institutional Controls
Alternative 2 does not actively remove contaminated soil or
sediments from the off-source area. The magnitude of remaining
risks following the implementation of this alternative is
equivalent to the risks currently present in the off-source area,
although following source control natural attenuation should
reduce risks to background levels.
In comparison to Alternative 1, Alternative 2 exhibits an
increased degree of long-term effectiveness due to the posting of
signs, which can remain on site indefinitely. These signs can be
expected to provide adequate warning to potentially affected
parties of the possible hazards posed by the off-source area.
Periodic inspection of the institutional controls put in place
would ensure that the signs remain in visible locations and are
free from overgrown vegetation, debris, etc.
Overall, this alternative provides a moderate degree of
long-term protectiveness.
35
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9.3.3 Alternative 3: Capping
Capping would generally have good long-term effectiveness.
The long-term effectiveness and permanence of capping may be
diminished by the possibility of the eventual deterioration of
the capping system. This deterioration could be caused by
natural factors such as local erosion (particularly in the tidal
channels). Periodic inspections of the capping system would be
necessary to ensure that the integrity of the cap remains
uncompromised. Capping material may require augmentation or
replacement should the original capping system become
compromised. The magnitude of residual risks posed by
contamination is not directly reduced by capping efforts/ but
instead the contamination is made inaccessible to potentially
affected parties and wildlife. It is anticipated that natural
processes could reduce organic contaminant concentrations after
capping measures have been instituted.
9.3.4 Alternative 4: Removal
Alternative 4 provides good long-term effectiveness and
permanence, provided that the extent of potentially hazardous
contaminant areas has been adequately estimated. Assuming that a
1-foot dredge depth for sediment and a two-foot dredge depth for
seep area soil would adequately remove the extent of
contamination, the magnitude of residual risks is negligible.
The dredging and removal of contamination is inherently permanent
and is considered to be a reliable method for the reduction of
on-site contamination.
The dredged sediment and seep soil areas would be covered
with clean fill. Since these areas would be graded and compacted
to an elevation similar to the surrounding grade, it is likely
that the capped areas would remain intact for long periods.
9.3.5 Comparison of Alternatives
Alternative 1 provides moderate long-term effectiveness.
Alternative 2 has moderate long-term effectiveness given adequate
maintenance of controls by the Tribes and successful
implementation of the interim action source control.
Alternatives 3 and 4 are likely to have good long-term
effectiveness although negative physical impacts to the wetlands
would be long lasting.
36
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9.4 Reduction in Toxicity, Mobility, and Volume Through
Treatment
9.4.1 Alternative 1: No-Action
Alternative 1 does not actively treat, contain, or remove
the contaminated soil or sediments found in the off-source area.
As a result, the only reduction in toxicity or volume would occur
through natural processes. Organic contaminants would be left to
degrade through natural processes such as dilution, dispersion,
and biodegradation. Inorganic contaminants are expected to be
covered with clean sediments during flooding/depositional
periods, thereby reducing their surface concentrations. This
alternative does not satisfy the statutory preference for
treatment as the principal method of risk reduction.
9.4.2 Alternative 2: Institutional Controls
Alternative 2 does not actively treat, contain, or remove
the contaminated soil or sediments found in the off-source area.
As a result, the only reduction in toxicity or volume would occur
through natural processes. Organic contaminants would be left to
degrade through natural processes such as dilution, dispersion,
and biodegradation. Inorganic contaminants can be expected to be
reduced in concentration through sedimentation processes over
time. This alternative does not satisfy the statutory preference
for treatment as the principal method of risk reduction,
9.4.3 Alternative 3: Capping
Alternative 3 does not actively treat or destroy
contaminated soil and sediments and therefore does not offer any
active reduction in toxicity or volume of contamination. Some
reduction in organic contaminant concentrations may occur through
natural processes following source control. Inorganic
contaminants can be expected to remain in the same concentration
in the subsurface environment over time. This alternative does
not satisfy the statutory preference for treatment. Mobility of
contamination is reduced in Alternative 3 by removing
contaminated soil and covering contaminated sediments with a
fine-grained material. This cap material will act to reduce the
possibility of contamination being scoured from "hot spots" and
carried away from the landfill by ebb tide flows in the off-
source area tidal channels.
9.4.4 Alternative 4: Removal
Removal and off-site disposal does not result in any
physical or chemical changes in the contaminants and does not
therefore provide any reduction in the toxicity or volume of the
contamination. Contaminant mobility is reduced due to the
removal of soil and sediments from an uncontrolled environment
37
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and the disposal these contaminants within a well-confined and
monitored landfill. Contaminant mobility is also reduced by the
mixture of flyash with potentially contaminated sediments for the
purposes of stabilization.
9.4.5 Comparison of Alternatives
None of the alternatives actively treat or destroy
contaminated soil and sediments. Therefore they do not offer any
active reduction in toxicity or volume of contamination through
treatment.
9.5 Short-Term Effectiveness
9.5.1 Alternative 1: No-Action
The no-action alternative is not effective in the short term
because the immediate risk to human health is not mitigated.
However, no risks are posed to workers since there are no efforts
required to implement this alternative. The no-action
alternative is readily implementable and will not result in any
negative environmental impacts, due to the lack of active
remedial efforts.
9.5.2 Alternative 2: Institutional Controls
Alternative 2 provides good short-term effectiveness. The
posting of signs should provide an immediate reduction of risk by
informing potentially affected parties of possible risks posed by
the off-source area. Minimal risks are posed to workers, the
public, and the environment since there is little effort required
to implement this alternative. Alternative 2 is readily
implementable and will not result in any negative environmental
impacts, due to the intrinsic lack of active remedial efforts.
9.5.3 Alternative 3: Capping
Capping is not effective in the short term. The greatest
short-term risks posed by Alternative 3 arise from worker
placement of pipelines and other work in the soft sediments. The
potential of a worker getting stuck in the sediment is high due
to the degree of manual labor required in this alternative. A
lesser degree of risk also exists during the construction of the
perimeter road. The use of heavy machinery in soft soils such as
those present in the off-source area poses a legitimate risk to
workers involved in the implementation of this alternative.
Additional risks are presented by leaving potentially hazardous
soil and sediments in place, and although containing these
materials through capping processes acts to reduce these rj..)-..
some degree of risk would remain.
38
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Environmental impacts associated with Alternative 3 are
substantial due to the construction of the access road and
capping activities occurring within the off-source area wetlands.
Significant impact to the wetlands contained in the off-source
area would occur as a result of the implementation of this
alternative. The placement of capping material over contaminated
sediments would impact portions of tidal channels by covering
contaminated areas with 1 foot of clean fine-grained fill. These
capping activities could significantly alter the majority of
affected tidal channels in the short term.
9.5.4 Alternative 4: Removal
Alternative 4 would not be effective in the short term. The
greatest short-term risks associated with Alternative 4 arise
during the construction of the roadways into the off-source area
and during dredging operations. The use of heavy machinery in
soft soils such as the soils present in the off-source area poses
a legitimate risk to workers involved in the implementation of
this alternative. The construction of a 200 foot by 200 foot
retention pond at the foot of the landfill would also pose risks
to workers. Treatment of wastewater resulting from dewatering
operations is expected to present minimal risk to workers.
Environmental impacts associated with Alternative 4 are
substantial due to the construction and dredging activities
occurring within the off-source area wetlands. Significant
impact to the wetlands contained in the off-source area would
occur as a result of the implementation of this alternative. The
construction of roadways and a sediment dewatering pond within
the off-source area would act to destroy approximately 240,000
square feet (5.5 acres) of wetland area.
9.5.5 Comparison of Alternatives
Alternative 2 has good short-term effectiveness given
adequate maintenance of controls by the Tribes. Active remedies
such as Alternatives 3 and 4 are likely to have poor short-term
effectiveness because of the negative physical impacts to the
wetlands during construction. Alternative 1 would not be
effective because collection of shellfish from contaminated areas
would not be prohibited.
9.6 Implementability
9.6.1 Alternative 1: No-Action
The no-action alternative is readily implementable. The
inherent lack of any active remedial efforts or institutional
control requirements makes Alternative 1 easily implementable,
39
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9.6.2 Alternative 2: Institutional Controls
Alternative 2 is considered to be readily implementable.
The technical and administrative aspects of Alternative 2 are
considered minimal. The inherent lack of any active remedial
efforts or additional monitoring requirements makes Alternative 2
easy to implement. Additional signage as necessary would be
posted by the Tribes or a potentially responsible party, in and
around the off-source area by the use of manual labor, boats, and
rafts. This technology is immediately available for use at the
Tulalip Landfill site. Monitoring in the off-source area is
already required by the interim remedial action ROD.
Because Alternative 2 would result in hazardous substances
remaining on the site above health-based levels, a statutory
review would be conducted no less often than every five years
after commencement of remedial action, to ensure that the remedy
continues to provide adequate protection of human health and the
environment.
9.6.3 Alternative 3: Capping
The technical and administrative aspects of Alternative 3
are readily implementable but have inherent difficulties. The
reliability of Alternative 3 for the tidal channel sediments is
dependent on the degree to which the capping system is
maintained. The construction of the perimeter roadway may
present some difficulties due to the construction requirements of
the off-source areas soft soils. The need to relocate the
capping equipment and pipelines to nine different locations would
also present implementation difficulties. The wetland area is
soft and presents challenges in moving personnel and equipment
over its surface. Soft sediments make overland travel difficult
and would require the placement of swamp mats or similar devices
over the soft soil to provide a firm surface. Even with these
mats, additional supports such as planks would be needed. This
technology is immediately available for full-scale use.
9.6.4 Alternative 4: Removal
The extensive construction and sediment dewatering
requirements of Alternative 4 present substantial implementation
difficulties. Construction of roadways and dewatering facilities
within the off-source area is expected to pose significant
difficulties due to extremely soft soil conditions. Dredging
operations within the off-source area wetlands will involve
substantial technical and administrative requirements. Dredged
sediments must be acceptable to a landfill before they are
transported. The required technology to construct Alternative 4
is readily available.
40
-------
9.6.5 Comparison of Alternatives
Active remediation of the wetlands such as capping
(Alternative 3) or removing contamination (Alternative 4) would
be technically very difficult due to the soft soil/sediment
present. To provide access to the impacted areas, Alternatives 3
and 4 would require construction of roads and other facilities in
addition to significant disturbance of the sediment. The damage
to the wetlands would significantly outweigh the benefits of the
cleanup. Also, remediation in such a difficult area makes
control of contaminant releases during remediation difficult.
The potential exists for contamination to be spread to other
areas, making cleanup less effective. As discussed above,
Alternatives 1 and 2 would be relatively simple to implement.
9.7 Cost
9.7.1 Alternative 1: No-Action
There is no cost associated with this alternative.
9.7.2 Alternative 2: Institutional Controls
The capital cost for this alternative is $15,410. Details
are shown in Table 6. Since the operation and maintenance (0/M)
cost would be minimal for this alternative, the estimated present
worth would be equal to the capital cost.
Table 6 - Detailed Costs for Alternative 2:
Controls/Natural Recovery
Institutional
xtem
Unit
NO*
Units
cost/unit
rotai cost
Mobilization
r»;«Mobii£ze
Sign Placement
. jffix;:: ^Signs' :.,,:,:;
% Boat and operator
Laborers
Lump Sum
Each
Day
Day
1
$5,000
$5,000
48
8
8
$50
$500
$250
Subtotal
Engineering
Contingency
Percent
Percent
5%
10%
Total Cost
$2,400
$4,000
$2,000
$13,400
$670
$1,340
$15.410
41
-------
9.7.3 Alternative 3: Capping
The capital cost for this alternative is $1,575,450.
Details are shown in Table 7. Since the operation and
maintenance (O/M) cost would be minimal for this alternative,
estimated present worth would be equal to the capital cost.
Table 7 - Detailed Cost for Alternative 3: Capping
the
Item
Mobilization
Mobilize equipment
Trailer rental
Office .. services.-: ;-;v ?:":: :.;:-.
Access Road Cons true tioj
Fill
Dozer
Excavator
Laborers
Operators
Geotextile
Capping Wetlands
Sand pump rental -
' Excavator rental
;, Swamp mats
-, cap fill > ,
,- - Laborers
'& operators - *- - -
- -"Pipe" rental
Capping Seep Soil
, Excavator rental
Dozer
Cap fill
Laborers
Operators
Soil transport and
disposal
Field Supervision
Field supervisor
Health and safety
officer
Engineering
Contingency
1
Unit
Lump Sum
(LS)
Mo.
Mo.
n
C.Y.
Mo.
Mo.
Day
Day
Sq. Ft.
Mo.
Mo.
LS
C.Y.
Day
Day
LS
*
Mo.
Mo.
C.Y.
Day
Day
C.Y.
Day
Day
Subtotal
4
%
otal Cost
No.
Units
1
3
3
18,000
1
1
20
20
164,000
t »
2
1.5
1
3, 100
36
36
1
1
1
9,400
20
20
9, 400
60
60
15
20
Cost/Unit
$30,000
$400
$600
;:":^':'::-?&
$8
$5,000
$4,000
$750
$700
$0.05
$6,000
$6,000
$7,000
$8
$750
$350
$10,000
,
$6,000
$5,000
$8
$500
$700
$70
$720
$500
Total Cost
$30,000
$1,200
$1,800
^m^m^-:^^,
$144,000
$5,000
$4,000
$15,000
$14,000
$8,200
-
$12,000
$9,000
$7,000
$24,800
$27,000
$12,600
$10,000
'
$6,000
$5,000
$75,200
$10,000
$14,000
$658,000
$43,200
$30,000
$1,167,000
$175,050
$233,400
$1.575.450
42
-------
9.7.4 Alternative 4: Removal
The capital cost for this alternative is $2,529,900.
Details are shown in Table 8. Since the operation and
maintenance (0/M) cost would be minimal for this alternative, the
estimated present worth would be equal to the capital cost.
Table 8 - Detailed Cost for Alternative 4:
Removal and Off-site Disposal
Ztara
Mobilization
Mobilize equipment
Tra Her r en t a 1
Office services
ACCOM Road Confttruetioi
-,Fill
- Dozer
' Excavator
; Laborers
Operators
-Geo text lie
Dredging
, Dredge rental
* Crane rental -
rf/Dewatering pond i. % <-,-
Jr Swamp mats v,,*,,*,4,4 .--. ,
^'Stabilization'' ->." <,<" -
V'^Laborer« "' - ',"'"-" ':;.. ",
-/.Operators , - - -
-!,I«aadout' ,
Transport and
dispose
Water treatment
Capping S«*p Soil
: «:;Ex cavator rental; :?; > H : -: ; '
-:>s-Dozer '- - :': :;
Cap fill
Laborers
Operators
:;Soil transport and
disposal
Field Supervision
Field supervisor
Health and safety
officer
Engineering
Contingency
1
Unit
Lump Sum
(LS)
Mo.
Mo.
m
C.Y.
Mo.
Mo.
Day
Day
Sq. Ft.
Mo.
Mo,
LS
LS
C.Y.
Day
Day
C.Y.
C.Y.
Gallon
Mo.
Mo.
C.Y.
Day
Day
C.Y.
Day
Day
Subtotal
%
%
otal Cost
MO. .
ttnlta
1
4
4
22,000
2
2
40
40
200,000
2
2
1
1
3, 100
40
40
4,600
4,600
600,000
1
1
9, 400
20
20
9, 400
80
80
15
20
Cost/Unit
$60,000
$400
$600
$8
$5,000
$4,000
$750
$700
$0. 05
$35,000
$7,000
$60, 000
$7, 000
$40
$750
$700
$2
$70
$0. 03
$6,000
$5,000
$8
$500
$700
$70
$720
$500
Total Cost
$60,000
$1,600
$2,400
$176,000
$10,000
$8,000
$30,000
$28,000
$10,000
$70,000
$14,000
$60,000
$7,000
$124,000
$30,000
$28,000
$9,200
$322,000
$18,000
$6,000
$5,000
$75,200
$10,000
$14,000
$658,000
357, 600
$40,000
$1,874,000
$281, 100
$374,800
$2.529,900
43
-------
9.7.5 Comparison of Alternatives
The cost of active remediation such as Alternatives 3 and 4,
is high compared to the benefits likely to be gained from the
cleanup. The relatively high cost is due to construction
difficulties associated with the soft sediment and unstable soil.
Alternative 2 is inexpensive and is very cost effective.
9.8 Tribal Acceptance
The Tulalip Tribes supports the implementation of
Alternative 2.
9.9 Community Acceptance
No comments were received from the general public.
44
-------
9.10 Summary of Comparison Analysis of Alternatives
Based upon the information contained above and comments from
the Tulalip Tribes and the public, Table 9 contains a summary of
EPA's comparison analysis. This summary is based upon comparing
the alternatives to each of the nine evaluation criteria.
Table 9 - Evaluation of Alternatives
Protection of ; Human
2) Compliance with
ARARs
3) long-term
4) Reduction
Through Treatment
5) Short-term - " " -
6) Zmplementability
7) Co»t
8) Tribal
Acceptance
9) CooBttunity
Acceptance
'
-1-
No Action
: j||;|»p|;| j Ji
Protective
Yes
Moderately
Effective
None
Mot
Effective
Simple
$0
NO
No Comment
Alterna
-2-
Institutional
Controls
' . : ::..-.-:-.-. :, ' : -.-.::. -.-..-'
' :: -:':- :'.\::'. :-:-;';' ;::">: :-r :''./:': :" ''s't'.t. ---.-
'.^S ,.:-.« JJM^4 .:: i:': .::! S-?
:-fV-' .::: « J-:, :«;-«: S ;«:-;;:::':
v.;,-:::..:;.;.i.-.:-H xS^**K S *:5*::::ii;
-::!::«:« 1
Yes
Moderately
Effective
None
Moderately
Effective
Simple
$15,410
Yes
No Comment
tive
-3-
Capping
'Protective :
NO
Effective
None
Not -
Effective
Difficult
$1,575,450
No
Mo Comment
-
-4-
Removal
Protective
No
Effective
None
> Kot ; '
Effective
Difficult
$2,529,900
No
No Comment;
10.0 SELECTED REMEDY
10.1 The On-source Remedy
The final remedy for this area is the remedy previously
documented in the March 1996 interim ROD. This remedy continues
to be protective of human health and the environment by
containing and preventing contact with the landfill wastes.
Major elements of the final on-source remedy (the previous remedy
selected in the interim ROD) include:
45
-------
Capping the landfill in accordance with the Washington State
Minimum Functional Standards for landfill closure.
Installing a landfill gas collection system. If necessary>
a gas treatment system will also be installed.
Monitoring the leachate mound within the landfill, the
perimeter leachate seeps, and landfill gas to ensure the
selected remedy is adequately containing the landfill
wastes.
Land use restrictions to protect the landfill cap.
Providing for operation and maintenance (O&M) to ensure the
integrity of the cap system.
The final selected remedy for the on-source area is expected to
stem the migration of contaminants from the landfill into the
surrounding estuary by minimizing the amount of rain water
infiltrating the wastes, thereby minimizing the generation of new
leachate. The remedial design for the on-source cover system was
completed on May 6, 1998. Construction of the cover system was
initiated immediately after the design approval and will take
approximately 2 years to complete. The ARARs presented in the
Interim ROD are still applicable or relevant and appropriate.
10.2 The Off-source Remedy
The selected remedy for the off-source area (wetlands), is
institutional controls. This selection assumes the completion of
the on-source remedy. Institutional controls would protect human
health by warning of the potential dangers associated with the
eating of fish and shellfish from the affected area. In
addition, the potential for this type of exposure is relatively
low given the site setting and access difficulties. Natural
attenuation of the organics and inorganics in the tidal channel
sediment would protect the marine receptors. Seep area soil that
presently exists above background concentrations would present a
small and decreasing incremental ecological risk to plants and
soil-dwelling organisms following source control. This
incremental risk is not significant since it affects a small
percentage of the off-source area.
This alternative consists of maintaining existing signs, and
as necessary, posting new signs along the perimeter of the
sloughs and landfill warning of the potential risk from
harvesting and eating fish and shellfish. Signs would be located
approximately every 300 to 600 feet along Steamboat Slough juiJ
46
-------
Ebey Slough. The Tulalip Tribes or the PRPs would be responsible
for installing any required new signs. Following construction of
the cover system (source control), natural recovery would reduce
the concentrations of organics and inorganics.
Inspections of the site would be performed to ensure the
warning signs were still in place and readable. The Tulalip
Tribes would be responsible for maintenance and enforcement of
the signs. Periodic monitoring of the impacted sediment and seep
soil is already required by the interim remedial action ROD.
Monitoring would ensure the contaminants were attenuating and not
migrating or increasing in concentrations.
EPA believes that it is essential to control and minimize
the release of contaminants to the environment with the
construction of the on-source cover system. The implementation
of institutional controls in the surrounding off-source area will
supplement the major remedy, the on-source remedy.
11.0 STATUTORY DETERMINATIONS
In combination, the on-source and off-source remedies
selected in this ROD are protective of human health and the
environment, comply with Federal, State, and Tribal requirements
that are legally applicable or relevant and appropriate to the
remedial action, and are cost-effective. This remedial action
utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable for this site.
However, the presumptive remedy approach for municipal landfills
selected in the interim ROD utilizes the remedial approach of
containment of wastes rather than treatment of wastes. Because
treatment of the principal threats of the site was not found to
be practicable, this remedy does not satisfy the statutory
preference for treatment as a principal element of the remedy.
11.1 Protection of Human Health and the Environment
In combination, the final on-source and off-source remedies
selected in this ROD are protective of human health and the
environment. The final remedy will permanently reduce the risks
presently posed to human health and the environment by preventing
contact with waste using a low permeability cover and
institutional controls. The low permeabilty cover will also
minimize infiltration, thus reducing the possibility of seep
contact, seep migration, and groundwater migration. As a result,
the final remedial action will also be protective of human health
and the environment in the long term.
47
-------
11.2 Applicable, Relevant and Appropriate Requirements (ARARs)
The selected remedy will comply with all Federal, State and
Tribal legally applicable, relevant and appropriate requirements.
For the on-source remedy, the ARARs presented in the interim ROD
are still applicable, or revelevant and appropriate. Since the
Tulalip Landfill is located on Tribal property, state regulatory
requirements do not necessarily apply to work performed in this
location. However, compliance with the Federal regulations and
the substantive portions of State regulations is prudent to
protect the environment.
11.2.1 Relevant and Appropriate Requirements
Washington Sediment Management Standards (WAC 173-204) are
relevant and appropriate requirements for the off-source remedial
action. The Washington Sediment Management Standards establish
numerical values for chemical constituents in sediments. These
standards are not legally applicable, because the site is located
on Tribal lands where State requirements are not enforceable.
However, the standards are relevant and appropriate because their
purpose is to provide standards for determining acceptable
levels of contaminants in sediments. The selected remedial
action for the off-source area complies with these standards
because, following source control, natural recovery will reduce
the concentrations of organics and inorganics.
11.2.2 To-Be-Considered (TBC)
Executive Order 11990 ("Protection of Wetlands"), as
implemented bv 40 C.F.R. Part 6. Appendix A is a TBC for the off-
source remedial action. Within and adjacent to wetlands,
Executive Order 11990 directs actions to be performed so as to
minimize the destruction, loss, or degradation of wetlands. The
off-source area of the site consists of ecologically productive
wetlands, and Executive Order 11990 is, therefore, to be
considered in selecting a remedy for the off-source area that
results in minimal destruction of, or impact to, these valuable
wetlands.
11.3 Cost-Effectiveness
The selected remedy is cost-effective because it provides
overall effectiveness proportional to its costs such that it
represents a reasonable value for the money to be spent.
11.4 Utilization of Permanent Solutions and Treatment
Technologies to the Maximum Extent Practicable
The selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized .in
a cost-effective manner at this site. The selected remedy
provides the best balance of tradeoffs among the alternatives
48
-------
with respect to the evaluation criteria. For the off-source
area, the criteria that were most critical in the selection
decision were short-term effectiveness, long-term effectiveness
and Tribal acceptability. Treatment was found to be
impracticable for the lower threat materials in the off-source
area. The remedy selected for the on-source area applied the
presumptive remedy approach for municipal-type landfills, which
utilizes the remedial approach of containment of wastes rather
than treatment of wastes.
11..5 Preference for Treatment as a Principal Element
The selected remedy does not meet the statutory preference
for treatment of a principal threat. The material in the off-
source area is not a principal threat, as that term is used in
EPA guidance. Treatment of this lower threat material has been
found to be impracticable. The remedy selected for the on-source
area applied the presumptive remedy approach for municipal-type
landfills, which utilizes the remedial approach of containment of
wastes rather than treatment of wastes.
11.6 Five-year Reviews
Because this remedial action will result in hazardous
substances remaining on the site above health-based levels, a
statutory review will be conducted no less often than every five
years after commencement of remedial action to ensure that the
remedy continues to provide adequate protection of human health
and the environment.
12.0 Documentation of Significant Changes
No significant changes to the remedy, as originally
identified in the Proposed Plan, were necessary.
13.0 RESPONSIVENESS SUMMARY
EPA held the required 30-day public comment period for the
Tulalip Landfill Off-Source Proposed Plan from August 3, 1998
through September 1, 1998. The Proposed Plan was mailed to the
415 people on EPA's Tulalip Landfill Superfund mailing list on
August 3, 1998. An announcement of the availability of the
Proposed Plan, a summary of the plan and information on how to
get more information was published in a display advertisement in
the Everett Herald on August 3, 1998. Both the Proposed Plan and
the Everett Herald notice indicated that readers could request
that the EPA hold a public meeting to discuss the plan.
49
-------
EPA received one written comment on the plan. No verbal
comments or requests for a public meeting about the plan were
received. The written comment was from the Tulalip Tribes. In
their comment letter the Tulalip Tribes indicated their support
for EPA's preferred alternative of institutional controls.
50
-------
TULALIP LANDFILL
FIGURES
-------
Figure 1
SOLE
SITE LOCATION MAP
-------
Figure 2
vJ iv..'-..f _ _X^ ;ll**^>j_Upstream '
> m i t I = 3 r c;
Explanation
Site Boundary
Source Area
Off-Source Area
Ofl-Sile Area
Tulalip Landfill
Delineation of Source, Off-Source
and Off-Site Areas
Quadrangle Series
Marysville. WA (1956. PR73)
-------
/ ""A '
-/ ""V" 1
Tula lip Laiuilill
Human Heahh CniuiUi
Groaior lhan } OiUoi ol
-------
Figure 4
Tulaiip Lnndhll |
Ecological Criteria Excee
-------
Figure 5
nemo
S*l I M»H1II SOIL '. -»-lC lOC»liOllS
High Ealuarlm- Uctlandk Soil Sjxpli lootlonii
/klC (OCAIlUI.
Of lANOTHL DOUIlOUlf
SO,ll,.'i lit «'<"> COOPS Or IllCiridk'.. U'.
o*ic o-' *' »'uf p*N<-it:»* i>/'j-'
l-KOKCIiCX. ACfl.CV
HI9n (tluorln* Wdtandt end
Sail Marih boll Somplt Locolionk
Remedial ln»uiligolion Riparl
MC Ik^blk
Jtili
-------
. ^
'<>% sou ii sois**_ .._i'.
Tulalip Landlill
Oil-Source Remediation Aroas
-------
TULALIP LANDFILL
A - TABLES
-------
Chemicals Detected in On-Source and Off-Source Media
Table A-1
Anal.te
VOCs
) 1-DiChloroelh.ine
T-Bulanone
2 He«anone
1 -Methyl- r-Pcntinont.'
Acetone
Benzene
BuKlftenzene
Carbon DisulMe
Chloioben^ene
Chloroelhane
Chlototoim
Chlotomethane
Civ1 2-Dichlctoclhene
fclh,lbenjcni>
Mcih,-lene rh:in.it>
Toluene
| Total X>i(fr.fS
Tnchiu'Gfliirne
On-Snurce Media
Zone 1
Gioundtvater
Zone 2
Gioundwater
Surface
Water
Surface
Soil
/
^
/
/
/
,'
/
/
/
/
/
/
/
/
/
s
/
j
/
/
/
/
/
/
/
/
Surface
Soil
0
Subsurface
L soil
Surface
Water
Leachate
Seej)'
f-Sniirr» Mwj
Surface
Sediment
ia
Subsurface
Sediment
Fish
Tissue
Clams
Small
Mammal
Tissue
/
/
/
/
/
/
/
/
/
s
/
/
/
/
^
BNAs
t I J-TfuTtivic-r.fn.-L'ne
I ?-DiChloiot/vn.'eni?
l 3 Dictiiofchenjcne
i l-l)ichliiioN.>n.'iint!
J J-niChlOlO|)Mtfl\Ol
? .l-Dimelh,lptitnoi
1 -Methylnaphlhalene
2-Methylnaphlhaiene
2-Melhylphenol
3 S'-Dichloroben/idine
> C More- 3- methylphenol
t-Metnylphenol
i-Nitrophenol
^cenaphtnylene
Acenaf)thpnp
Anthtar.ene
Oi-njOi j!jnlhi.u.i.'nf
./
/
.'
.'
/
/
/
/
/
/
/
/
/
/
/
J
j
/
s
s
/
/
^
/
/
^
/
^
/
/
/
/
/
/
/
/
^
/
/
/
^
/
s
s
/
/
/
/
s
/
s
s
/
/
^
/
/
/
/
/
/
/
/
/
/
/
/
^
/
1)1
II) S(|H.-|nl'iT IVV?
-------
Chemicals Detected in On-Source and Off-Source Media
/nal.te
Benjoiaip.fcne
BenjoiblMuOMnlhirni'
RenzofQ r> i'i vi ,\c<;<:
Brrvoif ;l;.i ,''idn:nvru>
Gen.rc.ic adit
bisr?-Chic.roi-in,i>rthvi
LiS(?-Elh,i!i--.i.: hihj'il?
1 R'll.ir »-n' ' M» .,,:..
Caitajiie
Chr,sene
Di-rvbul,ipnin3iate
Di-n-oclvlpxifia'ale
Dibenz/a rv.mthricene
Dibenzofuun
Dieth/iptiir.jidie
Omiemyiriijii.ii.iv
Fhioiantl'.ti'.e
Fluorene
lna«rnoi ll ! . '! ,'i-nv
n Nilroso ilrfvn.i. innnp
n.|Jil(O40 .Ii n i.iop>l.iMiiMtf
f JapMtf^J'trnr
PenlachlorL.p'H'ii.i
Hhcnjniliii'nr
Phenol
P,ttn.-
On. SDiiire Media
Zone 1
GrounOv.ater
/
/
/
/
/
/
/
/
Zone 2
Groundwaler
/
/
/
/
/
/
/
/
s
s
s
Surface
Water
/
/
/
s
/
/
/
/
/
Surface
Soil
/
/
s
/
/
/
/
/
/
o
Surface
Soil
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
^
^
/
/
/
/
Subsurface
Soil
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Surface
Water
/
/
Leachale
Seep'
/
/
/
/
/
/
s
/
/
/
/
/
/
/
/
/
/
/
/
/
/
f-Sourcp Mpfl
Surface
Sediment
/
/
/
/
/
/
^
/
/
/
/
/
/
/
/
/
/
/
lia
Subsurface
Sediment
/
/
/
/
/
/
/
/
s
/
/
s
' s
s
/
/
/
Fish
Tissue
Clams
/
/
/
/
s
/
/
^
/
/
/
Small
Mammal
Tissue
s
PCB.Pl'!.lll Kll'S
4 J.DDD
4 4. DDE
4 4 DOT
Aldiui
^t.xloi.R'1'
-'- lit i ;..
Atoclot-1?-:.'
.rr,cl;.i ir-i-
-i,.jy 1."- :
'f. Cl. 1 .'
/
/
/
/
/
/
/
/
/
/
/
/
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/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
S
/
/
/
i ivv;
-------
Chemicals Delected in On-Source and Off-Source Media
-njl.V
.iir.tu B»K":
t.i:la-!»HC
.MM MIK'
ijjmm.vHHC 'lin.l.inri
Difclclun
Endosuilan I
Endosull.m 1!
FndOSuIMn Mill IK-
Endwi
Endnn aUrh^l*:
Endfin kirlo"l-
qamma-chlci.runr
Henlachlji
Heptacnloi *(V"'Cl<;
Uetho-ychlvf
On Souice Media
Zoot 1
Gionnd.'.atci
/
/
X
Zone :
Groundv.atei'
/
/
/
/
/
Suilace
Water
Surface
Soil
0
Surface
Soil
/
/
/
/
/
/
/
/
/
/
Subsurface
Soil
/
/
/
Surface
Water
Leachale
Seep'
/
/
/
/
/
/
/
/
/
/
/
/
/
f-Source Mpf
Surface
Sediment
/
/
/
/
/
/
/
/
/
/
/
/
ia
Subsurface
Sediment
J
/
/
/
/
/
/
s
Fish
Tissue
Clams
/
/
/
/
/
/
Small
Mammal
Tissue
/
/
/
/
/ '
/
INORGANICS
.Mu"iiniii!-,
-nlirnony
-fsenic
D.iin/in
Beryllium
C Jdmtum
Calcium
Cnicmium
Oc.hall
Cr.ppti
Cv.iniile
Uon
Lead
Maqnesium
Manganese
Mricury
Nicl-el
Polabbiuni
Srlcrm/fn
i..i.sr
::...liuM.
r
./
/
/
/
/
/
/
/
/
,
/
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/
/
^
/
,'
s
/
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,
/
,'
/
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,'
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^
.'
,'
/
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j
s
/
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x
/
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.'
/
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/
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/
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/
^
/
s
s
s
s
s
s
/
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s
s
/
s
/
/
/
/
^
/
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^
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/
^
^
/
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>>
/
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^
x
/
x
^
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/
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s
s
/
s
/
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/
*
/
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/
/
/
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s
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s
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s
/
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x
/
^
/
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/
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/
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^
/
/
/
^
/
/
s
/
/
/
/ .
/
/
/
/
/
/
/
-------
Chemicals Detected in On-Source and Off-Source Media
Anai.te
Thallium
Van^Jiuni
Zinc
On. Source
Zone 1
GfOundwdler
/
/
/
Zone 2
Gioundwaler
/
/
/
Mcrtia
Surface
Water
/
/
Surface
. Soil
Surface
Soil
/
/
CONVENTIONAI.S
Amnionia f Jitroq-'n |[ /
/
l|
0
Subsurface
Soil
/
/
/
Surface
Water
/
Leachate
Seep1
/
/
/
/
f-Sourc* MmJ
Surface
Sediment
/
/
lia
Subsurface
Sediment
/
/
Fish
Tissue
/
/
Clams
/
X
/
Small
Mammal.
Tissue
/
/
r* uf i.ii i.Cn.'tc and oil
seeps
kn.i.n iw;
-------
Table A-2
Summary of Human Health Constituents of Potential Concern
Constituent
Semivolatile Organics
1-Methylnaphthalene
2-Methylnaphthalene
Acenaphthylene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g.h.i)perylene
Dibenz(a.h)anthracene
Dibenzofuran
lndeno(1 ,2,3-cd)pyrene
Phenanthrene
Purged Clams
Whole-Body Sculpin
Surface Soil/Sediment
.
y*
y*
y
y
y
y
y
y
y
y
y
Inorganics
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Lead
Manganese
Nickel
Selenium
Vanadium
y
y
y
y
y
y
y
y
y
y
y
y
y
y
y
y
y
y
y
i1
y
Pesticides and PCBs
4.4'-DDE
4.4--DDT
Aroclor 1016
Aroclor 1242
AlOClOl 1243
' i !
y
I
j \
y
I y" ;
Pane I of2
-------
Summary of Human Health Constituents of Potential Concern
Constituent
Aroclor 1254
Aroclor 1260
delta-BHC
Dieldrin
Heptachlor epoxide
Total PCBs
Purged Clams
y
Wtiole-Body Sculpin
y
/
Surface Soil/Sediment
y
y*
y
y
y
Constituent selected as COPC for given medium Will be further addressed in the CHHBRA.
Inadequate toxicity information available. Constituent retained as COPC for further qualitative discussion in the
CHHBRA
I>asw2of:
-------
Summary of Ecological Constituents of Potential Concern
It
li
'.
..Constituent
Semivolatile Organics
1.4-Dichlorobenzene
1-Methylnaphthalene
2.4-Dimethylphenol
4-Chloro-3-Methylphenol
2-Methylnaphtnalene
2-Methylphenol
4-MiMhylphenol
'' n.i| Milln in'
,iAi.cii;]|ili!liylonc
Anthracene
Bon?o(a)anthraceno
!Ben^o(a)pyrene
Benzo(b)fluoranthene
Benzo(g.h.i)perylene
Benzo(k)fluoranthene
'Benzole acid
hi$i.2-Einylhexyl)phtM;ilale
'Bnlvl^O'izylplilhal.'!!!1
Unpurged
Clams
/
./
/
/
/
y
/
Sculpin
Whole-
Body
Small
Mammals
/'
Surface
Soil
/
/
/
/
/
/
/
,/
/
/
/
/
Subsurface
Soil
/*
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Surface
Sediment
/
/
/
/
/
/
/
/
/
/
/
/
Subsurface
Sediment
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Great Blue
Heron
Northern
Harrier
0)
O
'ii-jo I of 5
-------
Summary of Ecological Constituents of Potential Concern
iConstiluent
|C;iib<-i
-------
Summary of Ecological Constituents of Potential Concern
Consliliienl
Arsenic
Barium
Beryllium
JCaclmium
1
jCluomium
jColJ.ill
Copper
:'Cy. limit?
Lf-n.1
,M;inci,inese
jMeicury
Nickel
Selenium
iSilver
Thailium
Vanadium
Zinc
Pesticides and PCBs
',4 4'-DCu:
'.A -I'-DOE
Unpurged
Clams
/'
/
/
/
/'
/
/
/
/
/
/
/'
/
/
/'
/'
/
Sculpin
Whole-
Body
/*
/'
/
/'
/
/
/'
/
/*
/
/
/*
/
/'
Small
Mammals
/
/
/
/
/*
/
/
/
/
/
/
/
/
/
Surface
Soil
/*
/
/
/
/'
/
/
/
/
/
/
/
/
/
/
/
/
Subsurface
Soil
/*
/'
/
/
/
/'
/
/
/
/
/
y
s
s
/
/*
/*
/
Surface
Sediment
/'
/
/
/
/*
/
/
/
/
/
/
/*
/
/*
/
/
/
Subsurface
Sediment
/*
/
/*
/
/*
/
/*
/.*
/
/
/
/
/
/
/
/
Great Blue
Heron
/*
X*
/
Northern
Harrier
/'
/
/
/
/
I'auc 3 of 5
-------
Summary of Ecological Constituents of Potential Concern
1
Constituent
..: 4 '-DDT
.'Klnii
'.-ilpha-BHC
i Aroclor 1016
Aroclor 1232
Aroclor 1242
Aroclor 1248
Aioclor 1254
Ainrloi 1260
Totc'il PCBs
beia-BHC
delta-BHC
Dieldrin
Endosulfan 1
Erulosulfan II
Endosulfan sulfate
Endrin
Eiuliiii aldehyde
Endnn ketone
cjamma-BHC (Lmdanc-)
Unpurged
Clams
/
/*
/
/
/
Sculpin
Whole-
Body
/
/
Small
Mammals
/
/
/
/
/*
/*
/*
/
Surface
Soil
/
/
/
/
/
/
/
/
/
/
/
/
/
Subsurface
Soil
/
/
/
/
/
/
/
/
/
/
/
/
/
Surface
Sediment
/
/
/
/*
/
/'
/
/
/
/
Subsurface
Sediment
/
/
/
/
/
/
/
/
/
/
y
/
/
Great Blue
Heron
/
/
Northern
Harrier
/
/
/'
/'
/
/*
aui- -I of 5
-------
Summary of Ecological Constituents of Potential Concern
Constituent
gnmma-Chlordane
I
|HeplacMlor
i
iHeptachlor epoxidt1
Melhoxychlor
Unpurged
Clams
/
/
Sculpin
Whole-
Body
/
Small
Mammals
/*
Surface
Soil
/
Subsurface
Soil
/
Surface
Sediment
/'
/
Subsurface
Sediment
/
/*
Great Blue
Heron
/
Northern
Harrier
/
/ - Cor.sMiienl selected js COPC for given medium Will be further addressed in the CBERA
..-..rit.'qi.inle lo^ic::, i-r-.-r-rung uiJoritMtion available Constituent retained as COPC for further quantitative/qualitative discussion in the CBERA
Page 5 of 5
2(< \II-UM IV'J.7
-------
Table A-4
Total Carcinogenic and Noncarcinogenic RME Risks for Each Scenario
Exposure Pathway
incidental Soil/Sediment Ingest/on
Soil/Sediment Dermal Contact
Fish Ingeslion
Shellfish Inpestion
Total
Carcmog
Recreational
User - Adult
65E-6
69E-8
NA
NA
66E-6
Subsistance
User Adult
NA
NA
93E-6
90E-4
9 1E-4
enic RISK
Subsistance
User- Child
NA
NA
1.4E-8
27E-5
27E-5
Combination'
Adult Risk
65E-6
69E-8
93E-6
9.0E-4
91E-4
Noncarcinogenic Risk
Recreational
User - Adu!t
0026
00034
NA
NA
0030
Subsistance
User - Adult
NA
NA
013
31
33
Subsistance
User- Child
NA
NA
00021
1 0
1 0
Combination*
Adult Risk
0026
00034
013
31
33
.» . L-; i *.ii:;|>hon *ruj i
Ml activity (such as hunting ai 11-.- site)
Table A-5
Total Carcinogenic and Noncarcinogenic CTE Risks for Each Scenario
Exposure Pathway
incidental Soil/Sediment Ingeslion
Soil/Sediment Dermal Contact
Fish Ingeslion
Shellfish Ingesdon
Total
Carcinogenic Effects
Recreational
User - Adult
74E-7
46E-9
NA
NA
74E--
Subsistence
User - Adult
NA
NA
12E-7
22E-5
22E-5
Subsistance
User- Child
NA
NA
75E-9
516-6
52E-6
Combination'
Adult Risk
7.4E-7
4.6E-9
12E-7
22E-5
23E-5
Noncarcinogenic Risk
Recreational
User - Adult
0021
00018
NA
NA
0023
Subsistance
User - Adult
NA
NA
0013
0.55
057
Subsistance
User- Child
NA
NA
0.0012
019
019
Combination'
Adult Risk
0021
0.0018
0.013
055
0.59
;o:nbinalion includes ">:> fi<»n both
jnce consumption ond recreational aclivily (such as hunting at the silu)
Pa- I of I
------- |