EPA Superfund
Record of Decision:
PB96-964602
EPA/ROD/R10-96/133
May 1996
Tulalip Landfill Site,
Marysville, WA
3/01/96
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RECORD OF DECISION
TULALIP LANDFILL SUPERFUND SITE
INTERIM REMEDIAL ACTION
MARYSVILLE, WASHINGTON
March 1996
U.S. Environmental Protection Agency
Region 10
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TABLE OF CONTENTS
DECLARATION BY REGIONAL ADMINISTRATOR .... i
LIST OF ACRONYMS iii
1.0 SITE DESCRIPTION 1
1.1 PHYSICAL SETTING 1
1.2 ECOLOGICAL SETTING .... 2
2. 0 SITE HISTORY AND ENFORCEMENT ACTIONS 4
3 .0 HIGHLIGHTS OF COMMUNITY PARTICIPATION - - - 9
4.0 SCOPE AND ROLE OF INTERIM RESPONSE ACTION 11
5.0 SUMMARY OF SITE CHARACTERISTICS 16
5.1 GEOLOGY 16
5.2 HYDROGEOLOGY 17
5.3 SITE DATA 19
5.3.1 On-Source Data (19);
5.3.2 Off-Source Data (21)
5.4 EXPOSURE PATHWAYS 23
6.0 DESCRIPTION OF SITE RISKS 24
6.1 HUMAN HEALTH EVALUATION 27
6.2 ECOLOGICAL EVALUATION 30
6.3 ASSESSMENT OF SITE 33
7.0 CLEANUP OBJECTIVES FOR THE INTERIM REMEDIAL ACTION ... 36
7.1 SUMMARY OF MAJOR APPLICABLE REQUIREMENTS 38
7.2 SUMMARY OF MAJOR RELEVANT AND APPROPRIATE
REQUIREMENTS 39
8.0 DESCRIPTION OF ALTERNATIVES 40
8.1 ALTERNATIVE 1 - NO ACTION 41
8.2 ALTERNATIVE 2 - ACTIVE LEACHATE SEEP INTERCEPTION
AND TREATMENT 42
8.3 ALTERNATIVE 2b - LEACHATE COLLECTION WITH
TREATMENT BERM 42
8.4 ALTERNATIVE 2b(ii) - LEACHATE SEEP COLLECTION WITH
DISCHARGE .TO PUBLICLY OWNED TREATMENT WORKS
(POTW) 43
8.5 ALTERNATIVE 3 - LEACHATE SEEP AND GROUND WATER
COLLECTION AND TREATMENT 44
8.6 ALTERNATIVE 4a - SOIL COVER WITH PASSIVE DRAINAGE . 45
8.7 ALTERNATIVE 4b - GEOSYNTHETIC COVER WITH ACTIVE
DRAINAGE 45
8.8 ALTERNATIVE 4c - GEOSYNTHETIC COVER WITH PASSIVE
DRAINAGE 46
8.9 ALTERNATIVE 4d - COMPOSITE COVER WITH PASSIVE
DRAINAGE 47
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8.10 ALTERNATIVE 5: GEOSYNTHETIC COVER WITH LEACHATE
SEEP CONTROL 48
8.11 ALTERNATIVE 6 - GEOSYNTHETIC COVER WITH LEACHATE
SEEP AND GROUND WATER CONTROLS 48
8.12 OTHER ALTERNATIVES 49
9.0 - SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES . . 50
10.0 THE SELECTED INTERIM REMEDY 59
10.1 DESCRIPTION OF THE SELECTED REMEDY 61
10.1.1 General Interim Remedy Requirements (61);
10.1.2 Regrading (62);
10.1.3 Landfill Cover System (62);
10.1.4 Air Controls (65);
10.1.5 Post-Construction Care (65);
10.1.6 Institutional Controls (67)
10.2 INTEGRATING THE INTERIM ACTION WITH LAND USE
PLANS 69
10.3 PERIODIC REVIEW 69
10.4 ESTIMATED COST OF THE SELECTED INTERIM REMEDY . '. 70
11.0 STATUTORY DETERMINATIONS 70
11.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT . . 71
11.2 COMPLIANCE WITH ARARS 71
11.2.1 Chemical-Specific ARARs (72);
11.2.2 Location-Specific ARARs (79);
11.2.3 Action-Specific ARARs (79);
11.2.4 To Be Considered (83)
11.3 COST-EFFECTIVENESS 85
11.4 UTILIZATION OF PERMANENT SOLUTIONS AND
ALTERNATIVE TREATMENT TECHNOLOGIES TO THE MAXIMUM
EXTENT PRACTICABLE . 89
11.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT . 90
12.0 DOCUMENTATION OF SIGNIFICANT CHANGES . 90
LIST OF. TABLES
1-1 Species of Concern
5-1 Chemicals Detected in On-Source and Off-Source Media
6-1 Comparison Numbers Used for the Human Health Evaluation
6-2 Summary of On-Source and Off-Source Site Data that Exceed
Human Health Comparison Numbers
6-3' Comparison Numbers Used for the Ecological Evaluation
6-4 Summary of On-Source Data that Exceed Ecological Comparison
Numbers
6-5 Summary of Off-Source Data that Exceed Ecological Comparison
Numbers
9-1 Cost Estimate Comparisons
10-1 Cost Estimate for Alternative 4c - Geosynthetic Cover with
Passive Drainage
11-1 Chemical-Specific ARARs for Surface Water at the Tulalip
Landfill Site
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LIST OF FIGURES
1-1 Site Location Map
1-2 Site Plan
5-1 Refuse Thickness Map
5-2. Generalized Geologic North-South Cross Section
5-3 Conceptual Hydrologic Model
5-4 Average Zone 2 Potentiometric Surface During 72-Hour Tidal
Study
5-5 Human Health Conceptual Site Model
5-6 Ecological Conceptual Site Model
6-1 Exceedances of Human Health Comparison Numbers Greater than
1 Orde'r of Magnitude
6-2 Exceedances of Ecological Comparison Numbers Greater than 1
Order of Magnitude
10-1 Decision Tree and Most Probable Cost for Landfill Gas System
APPENDICES
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Summary of Comparison of Remedial Alternatives 2b,
2b(ii), 3, 4a, and 4b in Relation to the NCP
Balancing Criteria
Cost Estimate for Contingent Landfill Gas
Treatment System
Guidance Documents for the Landfill Cover System
Responsiveness Summary
Specific EPA Review Comments on "Comparison of the
Leachate Collection and the Treatment Alternative
(2B) with the FML Cover Alternative (4C)," October
24, 1995, Colder Associates, Inc.
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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 interim
remedial action for the Tulalip Landfill 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 for this interim
action. The landfill 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
selected in this Record of Decision (ROD), may present an
imminent or substantial endangerment to public health, welfare,
or the environment.
Description of the Selected Remedy
The interim remedy documented by this interim ROD is
designed to protect public health and the environment by
containing and preventing contact with the landfill wastes.
Major elements of the selected 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
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
i.
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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.
The selected interim remedy is expected to allow productive
use of the landfill surface, with restrictions to prevent damage
to the cover system. The interim remedy shall be designed and
constructed to be compatible with the types of future use
activities described in the Big Flats Land Use Program, Tulalip
Landfill Remedial Investigation and Feasibility Study (July 10,
1994). When design and construction of the interim remedy are
complete, EPA and the Tulalip Tribes shall develop a document
titled "Routine Use of Tulalip ('Big Flats') Landfill," the
purpose of which shall be to ensure the continued integrity of
the cover system.
Statutory Determinations
The selected interim remedial action is protective of human
health and the environment, complies with Federal, State, and
Tribal requirements that are legally applicable or relevant and
appropriate to the remedial action, and is cost-effective. This
interim remedial action utilizes permanent solutions and
alternative treatment technologies to the maximum extent
practicable for this Site. The presumptive remedy approach for
municipal landfills utilizes the remedial approach of containment
of wastes rather than treatment of wastes. Because this action
does not constitute the final remedy for the Site, the statutory
preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element may be
addressed by the final response action.
Because the interim remedial action will result in hazardous
substances remaining on-site above health-based levels, a 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. Because this is an interim action ROD, review of
this site and this interim remedy will be ongoing as EPA
continues to develop final remedial alternatives for the wetlands
surrounding the landfill.
(
Chuck Clarke
Regional Administrator
U.S. EPA Region 10
11 .
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LIST OF ACRONYMS
AAL Acceptable Ambient Levels
AET Apparent Effects Threshold
AMBS Area of Major Biological Significance
AOC Administrative Order on Consent
ARAR Applicable or Relevant and Appropriate Requirement
ASTM American Society for Testing and Materials
ATSDR Agency for Toxic Substances and Disease Registry
AWQC Ambient Water Quality Criteria
BIA Bureau of Indian Affairs
CERCLA Comprehensive Environmental Response, Compensation, and
Liability Act
CQA Construction Quality Assurance
CWA Clean Water Act
CZMA Coastal Zone Management Act
DOD Department of Defense
EPA Environmental Protection Agency
FML Flexible Membrane Liner
FS Feasibility Study
FWPCA Federal Water Pollution Control Act
FWQC Federal Water Quality Criteria
gm gram
HEAST Health Effects Assessment Summary Tables
IRIS Integrated Risk Information System
MCC Marine Chronic Criteria
111.
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NFS Minimum Functional Standards
MOA Memorandum of Agreement
MSL Mean Sea Level
MTCA (Washington) Model Toxics Control Act
NCP National Contingency Plan
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
NTR National Toxics Rule
OSWER (EPA) Office of Solid Waste and Emergency Response
PAH Polycyclic Aromatic Hydrocarbon
PCB. Polychlorinated Biphenyl
POTW Publicly Owned Treatment Works
ppm parts per million
PQL Practical Quantitation Limit
PRP Potentially Responsible Party
PSAPCA Puget Sound Air Pollution Control Authority
RAO Remedial Action Objective
RCRA Resource Conservation and Recovery Act
RCW Revised Code of Washington
RI Remedial Investigation
RI/FS Remedial Investigation/Feasibility Study
ROD Record of Decision
SACM Superfund Accelerated Cleanup Model
SARA Superfund Amendments and Reauthorization Act
SDC Seattle Disposal Company
IV.
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SMA Shoreline•Management Act
SP Seep
TBC . To Be Considered
USCS Unified Soil Classification System
WAC Washington Administrative Code
v.
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1.0 SITE DESCRIPTION
1.1 PHYSICAL SETTING
The Tulalip Landfill occupies approximately 147 acres and is
located on a low-lying island (commonly referred to as North Ebey
Island) in the Snohomish River delta. This island is within the
floodplain of the Snohomish River. Located within the bounds of
the Tulalip Indian Reservation, the landfill lies generally
between Marysville and Everett, Washington (see Figure 1-1).
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 SON, Range 5E, Section 32.
Prior to landfilling activities, the land on which the
landfill is located consisted of relatively undisturbed
intertidal wetlands, and reached heights of about 3 to 6 feet
above mean sea level (MSL). Today, the landfill reaches heights
of about 12 to 20 feet above MSL. The"landfill is bounded by a
perimeter berm that is approximately 15 feet high. During
landfilling operations, barge canals were cut into t'Ke island to
allow water 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, wetlands adjacent to the canals were dredged prior to
placing the waste into the dredged areas. In general, these
barge canals were deeper than other parts of the landfill. The
former barge canals, which are now filled with waste, and other
physical features of the Tulalip Landfill area are shown in
Figure 1-2. The average depth of fill 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 waste -is
covered with silt, silty sand, clay and medium sand, and
demolition and construction debris at depths up to 11 feet.
The results of Remedial Investigation (RI) indicate that
there is a mound of contaminated ground water (landfill
"leachate") within the landfill waste. This leachate mound is
fed by precipitation, and its height varies between approximately
10-16 feet above MSL. Because the mound is considerably higher
than the mean sea level and the ground water level surrounding
the landfill, the weight of this leachate mound drives landfill
contaminants out and away from the landfill. Some of the
leachate (between approximately 5-35%) is pushed out the outer
edge of the perimeter berm and flows onto wetlands and into tidal
channels surrounding the landfill. Most of the leachate seeps
occur on the outside of the landfill berm, but one seep that was
sampled during the RI (SP-01) originates on the landfill surface.
The remainder of the leachate (approximately 65-95%) is driven
downward by the weight of the leachate mound into ground water
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beneath the landfill, where it migrates outward and is discharged
to waterways surrounding the landfill.
The leachate mound is primarily freshwater. The mound is
maintained mainly by precipitation, which falls in significant
quantities in the Puget Sound region. The landfill vicinity
typically receives between 35 and 40 inches of rain per year, and
experiences a rainy season (October to March) and a dry season
(April to September). In general, the leachate mound rises
during the rainy season, which is accompanied by visibly greater
amounts of leachate discharging through the perimeter seeps.
During the dry season the height of the mound falls, and the
amount of leachate discharging through the seeps decreases to
levels where some of the seeps cease to flow.
Commercial harvests of invertebrates and demersal and
anadromous fish occur in the immediate vicinity of the landfill
each year. The adjacent river system supports commercial and
sport fisheries. Important commercial species in the vicinity of
the Site include pink, chum, coho, and Chinook salmon; steelhead
and cutthroat trout; American shad, English sole, and Dungeness
crab. Site access is currently restricted, and the wetlands
adjacent to the west of the Site remain relatively undisturbed by
human activity. Additional wetlands lie immediately north of
Ebey Slough. People live north of Ebey Slough. The nearest
residence is located approximately 600 feet away from the
landfill perimeter.1 Smith Island is located south of Steamboat
Slough.
Ground water beneath the Site is brackish and therefore
unusable as a potable water source. Site studies indicate that
contaminated ground water from the landfill migrates to the,
wetlands and sloughs surrounding the Site and does not pose a
threat to ground water drinking water sources located across the
sloughs.
1.2 ECOLOGICAL SETTING
The areas surrounding the landfill have significant
aesthetic, environmental, economic, and recreational value. The
landfill is located within the Puget Sound Estuary, one of 28
estuaries in the country that has 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
1 Personal communication, Eric Winiecki, EPA, and Tom McKinsey,
Tulalip Tribes, February 8, 1996.
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substantially all, designated uses.2 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 (AMBS) for American shad and English sole by the
U.S. Fish and Wildlife Service.
The landfill is surrounded on all sides by environmentally
sensitive wetlands, including an area of approximately 160 acres
of salt marsh and mudflats located immediately west of the
landfill. 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. Wetlands
serve as unique ecosystems that support highly diverse and
abundant wildlife species. Plant species in the area, such as
cattail, bulrush, and sedge, provide shelter, feeding, and
nesting areas for wildlife. These plants serve as a food source
for waterfowl and other aquatic animals.
The Snohomish River supports a diverse aquatic community.
One•of the most important functions of estuarine wetlands is that
they provide nursery areas for many fish and wildlife species.
The tidal mudflats and emergent marsh habitat in the vicinity of
the Tulalip Landfill serve as spawning, nursery and feeding
habitats for a diverse population of demersal fish and
invertebrates.
Species that live in the estuarine wetlands around the
Tulalip Landfill include shorebirds and waterfowl, marsh hawk,
coyote, otter, and deer. Aquatic species residing in the Tulalip
Landfill area include salmon, cutthroat trout, clams, mussels,
shrimp, and juvenile Dungeness crab. Species of concern under
the federal Endangered Species Act or comparable Washington State
regulations that have been observed in the vicinity of the Site,
or that may be expected to use habitat areas near the Site, are
listed in Table 1-1. The bald eagle and the stellar (northern)
sea lion are considered threatened under State and Federal law.
A plant, the choriso bog orchid, has State status as a threatened
species.
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
Chapter 173-201 Washington Administrative Code (WAC), Water Quality
Standards for Surface Waters of the State of Washington, January 6, 1988.
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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
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.G. § 476. The
lands on which the landfill is located are currently held by the
United States in trust. The landfill is located on two property
parcels, one of which generally includes the eastern half of the
landfill, and the other includes the western half. The Tribes
established the Tulalip Section 17 Corporation, a federal
corporation chartered pursuant to Section 17 of the Indian
Reorganization Act, 25 U.S.C. § 477, which is the trust
beneficiary of the westerly parcel that was accepted into trust
by the United States in 1960. The Tulalip Tribes is the trust
beneficiary of the easterly parcel, accepted into trust in 1971.
To assist the Tribes' involvement in the Superfund process,
the Region entered into a Memorandum of Agreement (MOA) with the
Tribes on February 11, 1992. The MOA was amended on September 9,
1992, to include the Bureau of Indian Affairs as a signatory.
The Region also granted the Tribes a Superfund support agency
cooperative agreement under Section 104 of CERCLA, which provides
funds to support the Tribes' Superfund coordinator.
Operation of the Landfill 1964-1979
In 1964, the Tulalip Section 17 Corporation, as authorized
by a resolution of the Tribes, 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. Known then as "Big
Flats Landfill", the Site handled commercial and industrial
waste. The leases between the Tulalip Section 17 Corporation and
Seattle Disposal allowed specified waste disposal and related
activities for a "sanitary land fill operation" and required a
"final cleanup" of the Site. For the most part, the landfill did
not accept putriscible wastes, although the Tribes were allowed
to dispose of garbage. It was never intended that the landfill
accept putriscible waste or function in the capacity of a
municipal landfill. Between 1964 and 1979, it is reported that
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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, EPA filed a complaint in 1977 to
permanently stop the use of the landfill for disposal of waste.
In 1979 the landfill was closed and covered pursuant to the
Rivers and Harbors Act of 1899, 33 U.S.C. §§ 403 and 407, and the
Federal Water Pollution Control Act, 33 U.S.C. §§1311, 1319,
1341, and 1344, in accordance with a consent decree entered in
U.S. District Court for the Western District of Washington on
October 19, 1977, and amended on May 12, 1978. 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. Recent Site
studies indicate the waste is covered with approximately 12
inches to 11 feet of soil. However, the landfill surface was
left relatively flat, which subsequently resulted in poor
drainage and ponding of water on the landfill surface.
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. At the time, the Tribes hoped to obtain
surface grade materials from construction of a tunnel for
Interstate 90 leading into Seattle.
In order to perform the work, the Tribes applied to the Army
Corps of Engineers in March 1985 for a dredge and fill permit
pursuant to the Clean Water Act, 33 U.S. C. § 1342, to build a
dock for delivery of materials to the landfill. The Corps
granted the permit a year later, in March 1986.
In 1985-, the Tribes also applied to EPA for a National
Pollutant Discharge Elimination System ("NPDES") Permit for
placement of material on the landfill surface. The Corps had
decided to not include the placement of additional fill in a CWA
404 permit, writing to Tribes that the proposed capping project
was properly authorized pursuant to Section 402 of the Clean
Water Act under an NPDES permit. The Corps based its reasoning
on the fact that the Corps characterized the Tribes' efforts to
install a more effective cover over the Tulalip Landfill wastes
as "an essential feature of the landfill/wasting operation" at
the Site which the Corps believed was subject to Section 402 of
the CWA. EPA issued a five year 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
permit was amended in March 1987 to allow for the placement of
approved materials from other projects, when the Tribe did not
obtain soils from the 1-90 tunnel.
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From late 1986 to 1990, the Tulalip Section 17 Corporation,
in a joint venture with SEBB Corporation,3 contracted with R.W.
Rhine for the placement of capping materials. R.W. Rhine brought
materials from several demolition projects, .including
approximately 200,000 cubic yards of debris generated by the
demolition of structures from .the U.S. Navy's construction of a
new ."home port" in Everett, Washington. Rhine used the materials
brought to the Site to build a road network for "cells" to be
filled in during the capping project. An information request
response from R.W. Rhine lists the sources of additional capping
materials and demolition wastes that were deposited at the
landfill.
In 1990, EPA corresponded with the Tribes regarding the
disposal of materials without EPA approval. EPA's letter
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.
The National Priorities List (NPL)
In February and March 1988, EPA contractor Ecology &
Environment, Inc. (E&E) performed a Site Inspection of the
landfill for NPL evaluation. The inspection revealed groundwater
contamination with unacceptably high levels of arsenic, barium,
cadmium, chromium, lead, mercury, and silver. Water samples
taken in the wetlands adjacent to the Site showed exceedences of
marine chronic criteria for cadmium, chromium, and lead as well
as exceedences in marine acute criteria for copper, nickel and
zinc. In addition, a variety of metals were found in on-site
pools and leachate. The study concluded that contamination was
migrating off-site.
On July 29, 1991, EPA proposed adding the Tulalip Landfill
to the National Priorities List (NPL). Although the public
comment period on the proposed NPL listing closed in October
1991, SDC made 11 submissions of comments between May 1993 and
February 1995. On April 25, 1995, with the support of the
Governor of the State of Washington, EPA published the final rule
adding the Site to the NPL. In July 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. This
litigation is ongoing.
The Remedial Investigation and Feasibility Study
In August 1993, EPA signed an Administrative Order on
Consent with several Potentially Responsible Parties (the
3 SEBB Corporation no longer exists.
6
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Respondents)4 to conduct a Remedial Investigation and
Feasibility Study (RI/FS). These parties include 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, including sampling done recently
by the Respondents as part of the Remedial Investigation (RI),
show that landfill leachate leaving the Site exceeds water
quality criteria and standards for pesticides such as DDT,
heptachlor, and aldrin, polychlorinated biphenyls (commonly known
as PCBs), and heavy metals and other contaminants including
chromium, copper, lead, mercury, nickel, zinc, and ammonia. 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 ground water at the Site.
Citizen Suit under Clean Water Act and Resource Conservation and
Recovery Act (RCRA)
On March 30, 1994, Josie Razore and John Banchero filed suit
against the Tulalip Tribes, 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 defendants Tulalip Tribes, Tulalip
Section 17 Corporation, and BIA were in violation of their NPDES
permit and Section 301(a) of the Clean Water Act. The complaint
was amended to add counts under the citizen suit provision of the
Resource Conservation and Recovery Act (RCRA). In addition, the
complaint alleged that EPA has a mandatory duty to enforce the
NPDES permit and provisions of the. CWA and RCRA.
The plaintiffs requested that the court efrjoin further
violations of the CWA and RCRA, issue an injunction ordering the
defendants to stop the discharge of leachate without a permit,
and assess penalties for violation of the CWA and RCRA.
On September 23, 1994, the court dismissed the lawsuit,
holding that the court was deprived of jurisdiction pursuant to
CERCLA Section 113(h). The court found that the plaintiffs
remedy was "clearly" a "challenge" in its attempt to dictate
specific remedial actions at a Superfund Site and alter the
method and order for cleanup during an RI/FS and prior to a
determination of the ultimate remedial plan. The Plaintiffs
appealed the dismissal to the U.S. Court of Appeals for the Ninth
Circuit. The plaintiffs subsequently filed with the court an
For the purposes of this interim ROD, "Respondents" refers to some
or all of the PRPs that signed the RI/FS AOC.
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Appellants Memorandum of Emergency Motion for Injunction Pending
Appeal, which cited testimony from their expert (Ellingsworth)
that leachate is discharging from the Tulalip Landfill Site at
levels exceeding water quality criteria so that water quality
will "fall below the level that will sustain fish and other
aquatic life in the waters surrounding the landfill." 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.
Invocation of Dispute Resolution Under the 1993 AOC
On February 17, 1995, the Respondents to the 1993 AOC for
the conduct of the RI/FS invoked dispute resolution under
Paragraph 61 of the AOC with respect to a number of issues
including:
(1) EPA's denial of Respondents' request to modify the RI/FS
Work Plan to allow for the performance of additional work
under the AOC;
(2) the elimination of two remedial action alternatives
during the screening process-;5
(3) the exclusion of institutional controls as a stand-alone
remedy;
(4) brackish water AWQC evaluations;
(5) dissolved metals data in the evaluation of alternatives
and their compliance with ARARs; and
(6) mixing zones for measuring compliance with AWQCs.
On October 18, 1995, EPA Region 10's Deputy Regional
Administrator issued a final determination on the issues stated
above:
(1) EPA denied the request to modify'the Work Plan because
the request was untimely, would delay cleanup, was
inconsistent with the RI, was structurally flawed, and was
not needed to support the Source Area Containment
Feasibility Study (FS);
(2) EPA determined that the two disputed alternatives were
appropriately eliminated during the screening process and
should not be included in the FS, because they did not
comply with CERCLA, the NCP, and EPA guidance;
5 Detailed discussion of these two alternatives is provided in Section
8.12 - Other Alternatives.
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(3) EPA determined that institutional controls, as a stand-
alone remedy, was appropriately excluded from the FS during
the screening process;
(4) EPA determined that the use of brackish water AWQC
evaluations in the SAC-4 report was inappropriate and
inconsistent with State law, CERCLA, and the NCP;
(5) EPA determined that the use of limited dissolved metal
data did not prejudice RI/FS data collection and evaluation
efforts; and
(6) EPA determined that mixing zones would not be used for
measuring compliance with AWQC.
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 met these requirements by placing both documents in
the public "information repositories for the Site prior to the
start of the public comment period. EPA mailed copies of a fact
sheet summarizing the Proposed Plan on August 4, 1995 to
individuals on the mailing list. The fact sheet explained how
interested parties could get copies of the entire Proposed Plan.
Extra copies of the Proposed Plan were also made available at the
Marysville Public Library. EPA published a notice of the release
of the RI/FS and Proposed Plan in the Everett Herald on August 4,
1995, and the weekly Marysville Globe on August 9, 1995. Notice
of the 30 day public comment period and the public meeting
discussing the proposed plan were included in-the newspaper
notice. Prior to issuance of the Proposed Plan, the PRPs
requested a 30 day public comment period extension, which EPA
granted. A public meeting was held Q|j^August 22, 1995, at the
Snohomish County Public Utility District Auditorium in Everett,
Washington. The PRPs requested an additional public comment
period extension, which EPA granted by extending the comment
period to October 25, 1995, for a total comment period of 80
days. At the request of one of the Potentially Responsible
Parties, a second public meeting was held on October 3 in
Seattle. Written public comments received during the comment
period, and transcripts of the public meetings, are included in
the Administrative Record.
To date, the following Superfund community relations
activities have been conducted by EPA at the Tulalip Landfill
Site:
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December 1987
September 1988
July 1991
September 1993
November. 1993
November 1993
January 25, 1995
August 4, 1995
August 4, 1995
August 4, 1995
August 9, 1995
August 14, 1995
August 22, 1995
September 13, 1995
September 20, 1995
EPA released a fact sheet announcing a
sampling effort.
EPA released a fact sheet summarizing the
findings of the Site investigation.
EPA released a fact sheet announcing the
proposal of the Tulalip Site to the National
Priorities List.
EPA released a fact sheet which explained the
Superfund process and announced plans to talk
to citizens about concerns related to the
Tulalip Site.
EPA released the Community Relations Plan.
A fact sheet is released announcing the
beginning of the remedial investigation.
EPA mailed an update of the activities at the
Site, which included a general description of
the presumptive remedy containment approach
and its application to the Tulalip Site.
EPA mailed a fact sheet summarizing the
Proposed Plan for interim cleanup.
EPA released the Proposed Plan.
Newspaper Ad ran in the Everett Herald
announcing the public comment period and the
date and time of the public meeting.
Same newspaper ad from August 4, 1995, ran in
the Marysville Globe.
EPA received a request from one of the
Potentially Responsible Parties to extend the
public comment period. EPA ran a newspaper
ad in the Everett Herald announcing the
extension to the public comment period.
Public meeting on the Tulalip Landfill Site.
EPA released a fact sheet announcing the
extension to the public comment period and
announcing the time and location of an
additional public meeting.
EPA ran a newspaper ad in the Everett Herald
and in the Marysville Globe announcing
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another extension on the public comment
period and an additional public meeting to
1 discuss the Proposed Plan.
October 3, 1995 EPA held an additional public meeting, at the
request of one of the Potentially Responsible
Parties, to discuss the Proposed Plan. The
meeting was held from 10:00 a.m. to 5:30 p.m.
in Seattle.
October 25, 1995 Comment Period closed.
Selection of the interim 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 INTERIM RESPONSE ACTION
Based on EPA's experience of evaluating Superfund remedies
at many landfill sites across the country, the remedy for
landfills almost universally consists of containing the landfill
wastes in place to prevent migration of contaminants off of the
Site.6 Waste in Superfund landfills usually is present in large
volumes and is a heterogeneous mixture of commercial, industrial,
hazardous, and municipal wastes. Consistent with the National
Oil and Hazardous Substances Pollution Contingency Plan (or NCP),
EPA's expectation is that containment technologies will be
appropriate for landfill"waste because the volume and
heterogeneity of the waste generally make treatment impractical.
For the source areas7 of "Superfund" landfill sites, EPA
generally considers containment to be the appropriate response
action, or the "presumptive remedy." The objective of using a
presumptive remedy approach is to use past experience to
streamline site investigation, to speed up selection of cleanup
actions, and to increase the cost effectiveness of the remedy
selection process.
Containment remedies usually include installing a low
permeability cover to keep rain water from filtering down through
the landfill wastes. Containment may also include some form of
leachate collection and treatment, some form of landfill gas
collection, or some form of ground water control. EPA has
6 Presumptive Remedy for CERCLA Municipal Landfill Sites
(EPA 540-F-93-035, OSWER Directive #9355.0-49FS, September, 1993).
7 In general, a "source area" refers to an area of a site that acts as
a contaminant source to other areas.
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published several guidance documents that EPA Region 10 used to
design the RI/FS work plan that the Respondents followed,
including a streamlining manual entitled Conducting Remedial
Investigations/Feasibility Studies for CERCLA Municipal Landfill
Sites, February 1991 (OSWER Directive 9355.3-11) (also referred
to later as the Municipal Landfill Manual), Presumptive Remedies
for'Municipal Landfill Sites, April 1992 and February 1993 (EPA
Publication 9203.1-021), Presumptive Remedies, August 1992 (SACM
Bulletin Vol. 1, No.3), and Streamlining the RI/FS for CERCLA
Municipal Landfill Sites, September 1990. In addition, as
described below, EPA has conducted an analysis of potentially
available technologies for CERCLA landfills and found that
certain technologies are routinely and appropriately, screened out
on the basis of effectiveness, feasibility, or cost, consistent
with NCP Section 300.430(e)(7). The Feasibility Study Analysis
for CERCLA Municipal Landfills, September 1993, provides an
evaluation of 30 CERCLA landfill FS reports that support initial
identification and screening of technologies for selection of the
landfill remedy.
This streamlined presumptive remedy approach is appropriate
at Tulalip Landfill. In the RI/FS Work Plan (which is part of
the RI/FS AOC), the Tulalip Landfill was deemed appropriate for
remedial action because concentrations of contaminants at the
landfill exceeded the established standards of ambient water
quality criteria (RI/FS Work Plan, page 4-1). Containment is the
presumptive remedy which EPA found to be most commonly suited for
municipal landfills because these landfills, as well as the
Tulalip Landfill,8 share the following characteristics: (1)
large volume and heterogeneity of waste which make treatment
impractical; (2) limited number of alternatives for controlling
releases; (3) similar potential threats to human health and the
environment resulting from leachate generation, soil
contamination, landfill contents, landfill gases, and
contamination of ground water, surface water, sediments and
adjacent wetlands; and (4) the nature of waste deposition. See
generally "Presumptive Remedy for CERCLA Municipal Landfill
Sites," OSWER Dir. No. 9355.0-49FS, September, 1993. Because the
Tulalip Landfill shares these characteristics with municipal
landfills, EPA has concluded that the presumptive remedy approach
is appropriate for the Tulalip Landfill.
The streamlined approach that EPA has adopted at this Site
is consistent with'CERCLA, the NCP, and EPA guidance on
presumptive remedies. One important principle throughout the
RI/FS and remedy selection provisions in the NCP is the "bias for
action." EPA emphasized the "bias for action" in the NCP partly
8 While EPA considers the Tulalip Landfill to be a solid waste
landfill but not a municipal landfill, EPA believes that using the municipal
landfill presumptive remedy guidance at the Tulalip Landfill is appropriate.
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in response to criticisms that the Superfund program was too
slow, too costly, and unpredictable. At 40 C.F.R. Section
300.430(a)(1), the NCP states: "Remedial actions are to be
implemented as soon as site data and information make it possible
to do so." At 40 C.F.R. Section 300.430(a) (1) (ii) , the NCP
states:
"EPA generally shall consider the following general
principles of program management during the remedial
process:
(A) Sites should generally be remediated in operable units
when early actions are necessary or appropriate to achieve
significant risk reduction quickly, when phased analysis and
response is necessary or appropriate given the size or
complexity of the site, or to expedite the completion of
total site cleanup."
In the case of Tulalip Landfill, EPA believes an early, interim
remedial action is necessary and appropriate to achieve
significant risk reduction quickly. Because of the size and
complexity of the site, the RI/FS Work Plan was structured to
describe a phased analysis of the on-source and off-source areas.
Based on the results of the RI/FS, the completed Streamlined Risk
Assessment (see Section 6.0 - Description of Site Risks), and
public comments received on the Proposed Plan, a phased response
(i.e., early implementation of source control) is appropriate
while analysis of the wetlands surrounding the landfill
continues. Early implementation of source control will expedite
the completion of total site cleanup because it will stem the
flow of contaminants onto the off-source wetlands, thereby
eliminating chemical discharges to the wetlands that exceed
comparison numbers, and reducing total chemical loading from the
site to the wetlands surrounding the landfill. Early source
control may help the wetlands around the landfill recover
naturally from site discharges more quickly.
The "bias for action" generally involves a balancing
process, i.e., deciding how to balance the need for prompt, early
actions against the need for definitive site characterization.
This balancing process is specifically linked to the RI/FS,
including the risk assessment, at 40 C.F.R. Section
300.430(a)(2):
"Developing and conducting an RI/FS generally includes the
following activities: project scoping, data collection,
risk assessment, treatability studies, and analysis of
alternatives. The scope and timing of these activities
should be tailored to the nature and complexity of the
problem and the response alternatives being considered."
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The streamlined baseline risk assessment that has been completed
for the source area of the Tulalip Landfill Site reflects the
nature and complexity of the problem and the response
alternatives being considered.
The EPA guidance document "Presumptive Remedy for CERCLA
Municipal Landfill Sites (September 1993)"9 states:
"As a matter of policy, for the source area of municipal
landfills, a quantitative risk assessment that considers all
chemicals, their potential additive effects, etc., is not
necessary to establish a basis for action if ground water
data are available to demonstrate that contaminants clearly
exceed established standards or if other conditions exist
that provide a clear justification for action."
* * *
"Almost every municipal landfill site has some
characteristic that may require additional study, such as
leachate discharge to a wetland or significant surface water
run-off caused by drainage problems. These migration
pathways, as well as ground-water contamination that has
migrated away from the source, generally will require
characterization and a more comprehensive risk assessment to
determine whether action is warranted beyond the source area
and, if so, the type of action that is appropriate."
(underlining added).
The approach EPA has adopted for this site is wholly consistent
with this guidance. EPA is in the process of developing a more
comprehensive risk assessment which focuses on the wetland areas
surrounding the landfill. The comprehensive risk assessment will
be used to determine whether additional remedial action is
warranted in the wetlands, and if so, to support EPA's decision
regarding the type of action that is appropriate.
The Proposed Plan identified EPA's preferred alternative for
containing the landfill wastes through an Interim Remedial Action
by installing a low permeability cover over the waste.
Consistent with the program management principles of the NCP
Section 300.430(a) and the presumptive remedy guidance, EPA
proposed to proceed with an early action to contain the landfill
wastes, in this case with an early interim remedial action
operable unit. (An operable unit is a portion of a Superfund
9 In the preamble to the 1990 NCP, EPA stated that it was in the
process of developing guidance on expected remedies for specific types of
sites (e.g., municipal landfills) and specific types of waste (e.g., PCBs)
that will assist in streamlining decision-making and promoting greater
efficiency. See 55 Fed. Reg. at 8725.
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site; in this case, it refers to the source area of the
landfill). EPA plans to initiate design and construction of the
containment remedy an 1996.
The Feasibility Study (FS) for Tulalip Landfill is being
conducted by the Respondents in two parts; the first part,
called the Source Area Containment Feasibility Study, evaluates
various containment alternatives for the landfill source area.10
The final Source Area Containment Feasibility Study was submitted
to EPA on May 4, 1995. The second part, called the Site FS, may
be completed in summer, 1996. The purpose of the Site FS is to
identify and evaluate additional measures that could be taken to
clean up the wetlands and tidal channels that surround the source
area.1X '
The Streamlined Risk Assessment that has been completed by
EPA is sufficient for the purpose of selecting a containment
solution as an interim remedy. EPA's decision that an interim
remedial action is appropriate at this time based on current
information is consistent with CERCLA, the NCP, and EPA guidance.
This in an interim remedial action ROD. Any remedial action
for the area surrounding the landfill, or additional remedial
action for the source area, will be specified in the final Site
ROD. In preparation of a final remedial decision for the
wetlands surrounding the landfill (i.e., the "off-source" area),
EPA plans to complete the comprehensive baseline risk assessment,
evaluate the Site FS for the off-source area, and consider the
results of the 'source area containment remedy. The selected
interim remedy would be compatible with any possible future
cleanup actions at the Site, since it is expected to minimize the
potential for generation and migration of new leachate to these
off-source areas. EPA also expects to work closely with the
federal, tribal, and state natural resource trustees in
evaluating the appropriate response for the wetlands, sediments,
and other off-source resources. A review will be conducted no
less often than every five years after commencement of remedial
action to ensure that the interim remedy continues to provide
10 The source area of the landfill is considered to include
approximately 147 acres of waste and the surrounding perimeter landfill berm.
The off-source area is considered to include any part of the Site that is
located outside the perimeter berm. Figure 1-2 clearly shows the location of
the perimeter berm.
11 As a point of clarification, EPA notes that although the phased,
presumptive remedy approach has led to two separate FS reports (the SAC FS and
the Site FS) , and two separate risk assessments (the streamlined baseline risk
assessment for the on-source area, and the comprehensive baseline risk
assessment for the off-source area), there is only one RI Report for the Site.
The final RI Report (May, 1995) is available for public review in the
Administrative Record for this early/interim remedial action.
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adequate protection of human health and the environment. Because
this is an interim action ROD, review of this Site and this
remedy will be ongoing as EPA continues to develop final remedial
alternatives for the off-source area. If EPA's review indicates
that the interim action is not providing adequate protection,
additional containment action, such as implementation of a
perimeter leachate seep collection and treatment system, may be
necessary.
5.0 SUMMARY OF SITE CHARACTERISTICS
Three to four million tons of mixed commercial and
industrial waste was placed at the Tulalip Landfill between 1964
and 1979. Figure 5-1 is a map of the Site that shows the
thickness of the waste across the landfill. This waste is the
source of contamination at. the Site. Although no records detail
the exact types of waste buried at-Tulalip Landfill,
investigations indicate that most of the waste is commercial or
trade waste, including lumber, newspapers, cardboard, plastic
bags, rubber tires, scrap metal, glass, cloth, sawdust, and
cobbles. Although logs were banned from further disposal at the
Site in 1970, some logs have been identified in the fill in
addition to demolition debris and small boulders. Other waste in
the landfill includes: dredge spoils from at least one shipping
terminal project, hospital wastes, waste and still bottoms from
the manufacture of artificial vanillin, and small, incidental
amounts of municipal wastes. These types of wastes contain a
wide variety of hazardous substances that vary in tbxicity,
mobility, and carcinogenicity. During the late 1980's,
approximately 225,000 tons12 of additional materials was placed
on the surface of the landfill as part of a project to construct
a more effective landfill cover.
Data collected at the Site, including data from the Remedial
Investigation, shows that contaminants are migrating from the
waste mass into the surrounding environment. People, animals,
and plants are potentially exposed to these contaminants.
5.1 GEOLOGY
The landfill is situated on the Snohomish River delta in a
Quaternary topographic and structural basin known as the Puget
Sound lowland. - This lowland consists of a series of ridges and
valleys that tend to run north-south, which are the result of
repeated sediment deposition and erosion by glaciers and
associated glacial processes. The separate mesa-like plateaus of
the Puget Sound lowland are altered remnants of a former
continuous topographic surface that was dissected by the pre- and
12 See Revised Feasibility Study for Source Area Containment (SAC-4),
May 4, 1995, pages 37 and 38.
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post-Vashon erosion and further eroded by contemporary rivers
such as the Snohomish River.
Most of the surface and shallow subsurface geologic units
present in the landfill vicinity consist of unconsolidated
sediment deposited during the Vashon Stage of the Fraser
gla,ciation, which ended 11,000 years ago, or are the result of
recent sediment deposition by the Snohomish River and its
tributaries. The geologic unit on which the landfill was
developed is called the alluvium and estuarine deposits. This
geologic unit is the youngest deposit of regional significance in
the study area. Other regionally significant geologic units near
the landfill, in order of increasing age, include" the sandy
recessional outwash deposits; till consisting of an unsorted
mixture of clay, silt, sand, and gravel; advance outwash
consisting of layered sand overlain by sandy gravels; and
transitional beds which consist mostly of thick beds of clay,
silt, and fine sand.
Figure 5-2 is a general north-south cross section diagram of
the landfill that shows the stratigraphic units or zones that
have been identified at the Site. There are five of these:
• cover material which consists of 1 to 11.5 feet of primarily
sandy silt placed over the refuse during closure;
-• the refuse, ranging in thickness from 6 to 35 feet;
• a discontinuous silt layer with a thickness of 0 to 10 feet
which underlies the refuse throughout much of the landfill;
• "Zone 2," which consists of a silty sand layer ranging in
thickness from 15 to 22 feet; and
• a "Deeper Zone" which consists of sand, silty sand, and clay
and estuarine deposits.
Two of these units, the cover material and the refuse, exist at
the Site as a result of the landfilling activities, while the
other three units, the silt layer, Zone 2, and Deeper Zone, are
site-specific subunits of the alluvium and estuarine deposits.
The cover material, the refuse layer, Zone 2, and the Deeper Zone
are relatively permeable layers; water is able to move through
them. The silt layer is of relatively low permeability, but Site
studies show that the silt layer is not continuous. In addition
to natural breaks shown in Figure 5-2, the man-made barge canals
penetrate the silt layer.
5.2 HYDROGEOLOGY
Figure 5-3 shows a conceptual hydrologic model of the Site,
which illustrates current understanding of how contaminants
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migrate from the landfill to the surrounding environment. When
precipitation falls on the landfill, most of the rain water
infiltrates down through the cover soil and sinks down into the
refuse layer, picking up contamination from the waste as it
moves. Over the years, a large mound of this contaminated ground
water, or leachate, has accumulated within the refuse layer. In
Figure 5-3, this leachate mound is described as the "Zone 1"
aquifer. The leachate mound within the waste ranges in height
from approximately 11 to 16 feet above mean sea level (MSL) which
corresponds to a saturated refuse thickness of 14 to 26 feet.
The amount of leachate in Zone 1 fluctuates seasonally; in
winter months when there is more precipitation, and infiltration
into the landfill exceeds the discharge rate, the height of the
leachate mound tends to rise within the waste; in the drier
summer months when the infiltration rate falls below the
discharge rate, the height of the leachate mound tends to fall.
The results of the RI indicate that the leachate mound is
not affected by tidal fluctuations of the surface water
surrounding the landfill (ie., the height of the leachate mound
is unaffected by tidal action). The mean high tidal water level
in the landfill vicinity is about 4 feet above MSL, and the mean
low tidal water level is about 3 feet below MSL. The highest
tide level ever recorded in the area was about 8.5 feet above
MSL, and the lowest was about 9.5 feet below MSL. The wetlands
surrounding the landfill range between approximately 3 to 6 feet
above MSL, so during a high tide the water can submerge the lower
part of the landfill berm. The surface water surrounding the
landfill contains high levels of salt compared to the freshwater
nature of the leachate mound, which suggests that if any surface
water surrounding the landfill infiltrates the landfill waste due
to tidal fluctuations, such infiltration is minimal. EPA is
unaware of any flood events that have submerged .the landfill
surface.
The leachate in Zone 1 discharges to the wetlands and
sloughs surrounding the landfill, carrying contaminants from the
landfill with it. Some of this leachate,. between approximately
5% to 35% of the total, discharges through the perimeter landfill
berm onto wetlands surrounding the Site, and can be visually
observed exiting the external face of the berm as "leachate
seeps." There are numerous leachate seeps around the landfill
perimeter, some of which are transient in nature. The remainder
of the Zone 1 leachate, estimated at about 65% to 95% of the
total, is driven downward by the weight of the leachate mound
through holes in the silt layer, and through the silt layer
itself, into the Zone 2 aquifer beneath the landfill. Figure 5-4
is a map that shows the average potentiometric surface in Zone 2
over a 72-hour period in March, 1994. The potentiometric surface
of the Zone 2 aquifer shown in this figure suggests that the
leachate mound within the landfill exerts pressure on the Zone 2
aquifer, indicating that leachate is being driven down through
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the silt layer or through gaps in the silt layer, into Zone 2 and
outward away from the landfill. The RI indicates that this Zone
2 leachate migrates beneath the perimeter berm and discharges to
surrounding surface waters, principally into Ebey Slough to the
north and Steamboat Slough to the south. On an annual basis, the
perimeter seeps contribute between approximately 5.3 million
gallons to '13.1 million gallons per year to the surrounding
environment, and the leachate contribution through Zone 2 is
between approximately 21 million and 175 million gallons per
year.
5.3 SITE DATA
This section briefly summarizes the sampling of on-source
and off-source media that has been performed at the Site, and
lists the most frequently detected chemicals that were found in
each media. For purposes of discussion in this interim ROD,
examples of Site sampling "media" include: surface water, Zone 1
ground water, Zone 2 ground water, Deeper Zone ground water,
leachate seeps, surface soil, subsurface soil, surface sediment,
and fish tissue). "On-source" data refers to chemical data
collected from the landfill source area, which includes the
landfill surface and contents, the surrounding perimeter landfill
berm, and ground water within and beneath the waste. "Off-
source" data refers to chemical data collected in the wetland
areas and tributaries adjacent to the berm and bounded by Ebey
and Steamboat Sloughs (leachate exiting the exterior face of the
perimeter berm is considered to be off-source).
5.3.1 On-Source Data
Sample data collected in on-source media (surface water and
surface soil;13 Zone 1, Zone 2, and Deeper Zone groundwater; and
surface water) are briefly described below.
Surface Water: During the 1988 Site Investigation, water
samples were collected from five pooled surface water locations
on the landfill. The following chemicals were detected" in 50% or
more of these surface water samples: acetone, naphthalene,
aluminum, barium, calcium, chromium, cobalt, copper, iron, lead,
magnesium, manganese, nickel, potassium, sodium, and zinc.14
13 Because the on-source surface water and on-source surface soil data
was taken in 1988, prior to the RI, it may not be representative of current
landfill conditions. EPA has considered the 1988 data but has not relied upon
it to support any conclusions in this interim ROD. EPA's consideration of
these data has not changed EPA's conclusions in this interim ROD.
14 In other words, acetone was detected in at least 50% of all on-
source surface water samples; naphthalene was detected in at least.50% of all
on-source surface water samples, etc.
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Leachate seep SP-01 is a seep that originates on the
landfill surface, above the berm, and discharges off the berm
into the surrounding wetlands. In addition to the pooled water
samples, data from this seep is considered to be on-source
surface water data. Detection frequency information for this
seep is summarized below, as part of the detection frequency
summary of all of the leachate seeps.
Surface Soil: Surface soil samples were also collected at
these five sample locations during the 1988 Site Investigation.
Some chemicals were detected in these samples. However, none of
the chemicals in the analysis were found in more than 50% of all
the samples that were taken.
Zone 1 Groundwater: Groundwater was sampled from Zone 1,
which is the leachate mound located in the refuse layer, at four
well locations. These wells were each sampled once near the
beginning of the RI. Chemicals that were detected in 50% or more
of all the samples taken from the Zone 1 wells include volatile
organic compounds (benzene, 2-hexanone, toluene, chlorobenzene,
ethylbenzene, total xylene, 1,3-dichlorobenzene, 1,4-
dichlorobenzene); semi-volatile organic compounds (2,4-
dimethylphenol, naphthalene, 2-methylnaphthalene, acenaphthene,
dibenzofuran, diethylphthalate, fluorene, phenanthrene,
anthracene, retene); the semi-volatile indicator compound
dehydroabietic acid; pesticides (gamma-BHC [Lindane], heptachlor
epoxide); total metals (aluminum, antimony, arsenic, barium,
calcium, chromium, cobalt, copper, iron, lead, magnesium,
manganese, potassium, sodium, zinc); and total cyanide, ammonia
nitrogen, and total phenol.
Zone 2 Groundwater:' Groundwater was^sampled from Zone 2,
which is located below the refuse layer, at 24 well locations.
Six sampling rounds were conducted for Zone 2 'wells located on
landfill perimeter berm, one round every other month, over a 12-
month period during the RI. Zone 2 wells located in the landfill
interior were sampled just once during the first sampling round.
Chemicals that were detected in 50% or more of all the samples
taken from the Zone 2 wells include the semi-volatile compound
bis(2-ethylhexyl)phthalate; total metals (aluminum, barium,
calcium, chromium, iron, magnesium, manganese, potassium, sodium,
vanadium); and ammonia nitrogen and total phenol.
Deeper Zone Groundwater: Deposits beneath the Zone 2
consist of,sand, silty sand, and clay and are referred to as the
Deeper Zone. Two monitoring wells were installed in the deeper
Zone, and one sample was taken from each of these wells during
the first sampling round. Chemicals that were detected in 50% or
more of the samples taken from the deeper zone wells include
volatile organic compounds (acetone, chloroform, 2-butanone,
toluene, total xylene); the semi-volatile organic compound
diethylphthalate, the semi-volatile indicator compound
20
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dehydroabletic acid; total metals (barium, cadmium, calcium,
iron, magnesium, manganese, potassium, selenium, sodium, zinc);
and total cyanide, ammonia nitrogen, and total phenol.
5.3.2 Off-Source Data
. Sample data collected in off-source media (surface and
subsurface soil, surface and subsurface sediment, surface water,
and leachate seeps) are briefly summarized below:
Surface Soil: Surface soil was sampled from grids extending
into the wetlands around leachate seeps and from fifteen
locations in the high estuarine wetlands and salt marshes located
immediately west of the landfill. In all, 106 off-source soil
samples were taken, including 5 replicate samples collected by
the Respondents and 10 duplicate samples taken by EPA.
Chemicals that were detected in 50% or more of all the soil
samples taken by the Respondents from the high estuarine
wetlands, which are located just off the western boundary of the
landfill, include the semi-volatile organic compound indicator
dehydroabietic acid; polynuclear aromatic hydrocarbons
(phenanthrene, fluoranthene); total metals (aluminum, arsenic,
barium, calcium, chromium, cobalt, copper, iron, lead, magnesium,
manganese, nickel, potassium, sodium, vanadium, zinc); and total
cyanide.
Chemicals that were detected in 50% or more of all the soil
samples taken by the Respondents near the leachate seeps include
semi-volatile organic compounds (phenanthrene, fluoranthene,
pyrene, chrysene, benzo(b)fluoranthene); the semi-volatile
indicator compound dehydroabietic acid; polynuclear aromatic
hydrocarbons (phenanthrene, fluoranthene); and total metals
(aluminum, arsenic, barium, calcium, chromium, cobalt, copper,
iron, lead, magnesium, manganese, nickel, potassium, sodium,
vanadium, zinc).
Subsurface Soil:- Subsurface soil was sampled near six .of
the leachate seeps along the edges of the landfill. Samples were
taken at 6-inch intervals to a depth of 2 feet. In all, 20 off-
source subsurface soil samples were taken, including two
duplicate samples collected by EPA. Chemicals that were detected
in 50% or more of all the subsurface soil samples taken by the
Respondents include semivolatile organic compounds (1,4-
dichlorobenzene, 2-methylnaphthalene, acenaphthene, dibenzofuran,
carbazole, pyrene, chrysene, bis(2-ethylhexyl)phthalate,
benzo(b)fluoranthene); the semi-volatile indicator compound
dehydroabietic acid; polynuclear aromatic hydrocarbons
(naphthalene, fluorine, phenanthrene, anthracene, fluoranthene,
pyrene); the pesticide gamma-BHC (Lindane); the polychlorinated
biphenyl ("PCB") Aroclor-1242; .and total metals (aluminum,
21
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arsenic, barium, calcium, chromium, cobalt, copper, iron, lead,
magnesium, manganese, nickel, potassium, sodium, vanadium, zinc).
Surface Sediment: Surface sediment was sampled at 46
locations around the landfill. In all, 52 samples were taken,
including six duplicate samples collected by EPA. Chemicals that
were detected in 50% or more of off-source surface sediment
samples taken by the Respondents include: 4-Methylphenol,
phenol, phenanthrene, fluoranthene, pyrene, chrysene,
benzo(a)pyrene, aluminum, arsenic, barium, calcium, chromium,
cobalt, copper, iron, lead, magnesium, manganese, mercury,
nickel, potassium, sodium, vanadium, and zinc.
Subsurface Sediment: Subsurface sediment was sampled at six
of the sediment sampling locations. Samples were taken at 6-inch
intervals to a depth of 2.0 feet. In all, 20 samples were taken,
including two duplicate samples collected by EPA. Chemicals that
were detected in 50% or more of all the off-source subsurface
sediment samples taken by the Respondents include
2-Methylnapthalene, 4-methylphenol, dibenzofuran, napthalene,
acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene,
pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene,
benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene,
benzo(g,h,i)perylene, aluminum, arsenic, barium, calcium,
chromium, cobalt, copper, iron, lead, magnesium, manganese,
mercury, nickel, potassium, selenium, sodium, vanadium, and zinc.
Surface Water: Surface water was sampled at 18 locations
around the landfill. Twenty samples were taken, including two
duplicate samples collected by EPA. Chemicals that were detected
in 50% or more of all the surface water samples taken by the
Respondents include the following total metals: aluminum, barium,
calcium, and iron.15
Leachate Seeps: Leachate was sampled at 10 off-source
locations around the landfill (leachate seeps SP02 through SP11)
and one on-source location (SP01). With the exception of
leachate seep SP01, in general, leachate seep samples were taken
at the point where leachate exited the perimeter landfill berm
before discharging onto the wetlands surrounding the Site. Six
sampling rounds were conducted during the RI, one every other
month, for a year. Fifty-five samples were taken, including
seven duplicate samples collected by EPA. Chemicals that were
detected in 50% or more of leachate samples taken by the
15 Lead, which exceeded Ambient Water Quality Criteria at one off-
source surface water location, was detected in 40% of all off-source surface
water samples.
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Respondents during rounds 1 through 516 include volatile organic
compounds (benzene, chlorobenzene, total xylene, 1,4-
dichlorobenzene); semi-volatile organic compounds (2,4-
dimethylphenol, naphthalene, 2-methylnaphthalene, acenaphthene,
dibenzofuran, fluorine, phenanthrene, retene); the semi-volatile
indicator compound dehydroabietic acid; total metals (aluminum,
arsenic, barium, calcium, chromium, cobalt, copper, iron, lead,
magnesium, manganese, potassium, nickel, sodium, vanadium, zinc);
ammonia nitrogen and total phenol.17
Fish Tissue: Twenty-four composite fish tissue samples were
taken from tidal channels surrounding the landfill. Some of .the
chemicals that were detected in 50% or more of all the fish
tissue samples include PCB Aroclor-1254, mercury, arsenic,
chromium, and vanadium.
5.4 EXPOSURE PATHWAYS
The results of Site studies indicate that contaminants are
migrating from the landfill to the surrounding environment.
Table 5-1 lists chemicals that have been found in various on-
source and off-source media. The high number of chemicals that
are common across different media, in combination with
information that has been learned about the Site geology and
hydrogeology, indicates that water infiltrating the waste
mobilizes chemicals in the waste, and then transports them off
site via the perimeter leachate seeps and Zone 2 ground water.
These chemicals from the landfill have subsequently accumulated
in off-source media including surface soil, subsurface soil,
surface sediment, subsurface sediment, and fish tissue. Page 6-6
of the RI concludes that surface soil chemical concentrations
were "highest nearest the seeps discharge points and lower further
from the seeps, which suggests that chemicals migrating from the
landfill are likely causing elevated chemical concentrations in
off-source areas.
There are many potential routes, or pathways, by which
exposure to landfill contaminants can occur. Figure 5-5 shows a
Human Health Conceptual Site Model, which describes the potential
pathways for human exposure to Site contaminants. Potential
pathways evaluated in the streamlined baseline Risk Assessment
16 The source of this summary of the leachate seep data is Remedial
Investigation Table 4-20, entitled "Summary of Leachate Seep Water Analytical
Results for Rounds 1 through 5. Apparently, leachate data from the sixth
round was not yet available for inclusion in this Table.
17 In many of the water media, dissolved metals were also detected in
addition to total metals. In the leachate seep samples, for example,
dissolved metals that were found in 50% or more of all the samples include
aluminum, antimony, arsenic, barium, cadmium, calcium, chromium, iron,
magnesium, manganese, potassium, nickel, sodium, and zinc.
23
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for Interim Remedial Action (the "Streamlined Risk Assessment")
include ingestion of on-source and off-source soil, ingestion of
fish or shellfish that have contacted leachate, ingestion of fish
or shellfish in surface water near the Site, and ingestion of
off-source sediment.
Figure 5-6 is an Ecological Conceptual Site Model, which
shows the potential exposure pathways for ecological receptors
including animals and plants. Potential pathways for ecological
receptors evaluated in the Streamlined Risk Assessment include
plant and subsequent bird and mammal uptake of contaminants in
off-source and on-source soil; invertebrates and fish uptake
associated with leachate, off-source and on-source surface water;
and invertebrate uptake associated with off-source sediment. As
Figures 5-5 and 5-6 indicate, additional potential exposure
pathways for terrestrial and aquatic organisms and humans will be
evaluated in a comprehensive baseline risk assessment which EPA
has begun to prepare.
People that use the on-source or off-source areas of the
Site are potentially exposed to contaminants in or emanating from
the landfill. People that could be exposed include current and
future recreational users, and future industrial or commercial
users.18 Potentially exposed ecological populations include
plants on or near the Site; and animals, including fish, otter,
rodents, water fowl, and raptors that use the Site or the
wetlands surrounding the Site.
6.0 DESCRIPTION OP SITE RISKS
Using sample data collected from the Site, the U.S.
Environmental Protection Agency (EPA) conducted a streamlined
baseline risk assessment to evaluate the health and/or
environmental problems that would result if the contamination is
not addressed. This qualitative analysis, called the Tulalip
Landfill Risk Assessment for Interim Remedial Action, August,
1995 (the "Streamlined Risk Assessment"), has been prepared in
accordance with the National Contingency Plan (NGP) and EPA
guidances on risk assessments and presumptive remedies.19
18 Light industrial or commercial use is consistent with potential
future land uses as identified by the Tulalip Tribes (see "Big Flats Land Use
Program", Tulalip Tribes of Washington, July 10, 1994, in the administrative
record).
19 The Tulalip Landfill Risk Assessment for Interim Remedial Action is
a streamlined baseline risk assessment as described by EPA guidance -- see
Streamlining the RI/FS for CERCLA Municipal Landfill Sites (OSWER Directive:
9355.3-11FS, December, 1990, page 3, section entitled "Streamlining the
Baseline Risk Assessment." See also the Responsiveness Summary for this ROD.
24
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The preamble to the National Contingency Plan (NCP) and EPA
guidance provides information on how EPA suggests risk
assessments may be .conducted at Superfund sites of varying scope
and complexity. The Streamlined Risk Assessment is consistent
with the NCP preamble language, which emphasizes a "bias for
action" in how to balance the need for prompt, early actions
against the need for definitive site characterization. The NCP
states:
"EPA expects to take early action at sites where
appropriate, and to remediate sites in phases using operable
units as early actions to eliminate, reduce or control the
hazards posed by a site or to expedite the completion of
total site cleanup. In deciding whether to initiate early
actions, EPA must balance the desire to definitively
characterize site risks and analyze alternative remedial
approaches for addressing those threats in great detail with
the desire to implement protective measures quickly.
Consistent with today's management principles, EPA intends
to perform this balancing with a bias for initiating
response actions necessary or appropriate to eliminate,
reduce, or control hazards posed by a site as early as
possible."
***
"To implement an early action under remedial authority, an
operable unit for which an interim action is appropriate is
identified. Data sufficient to support the interim action
decision is extracted from the ongoing RI/FS that is
underway for the site or final operable unit and an
appropriate set of alternatives is evaluated...A completed
baseline risk assessment generally will not be available or
necessary to justify an interim action."
***
"Qualitative risk information should be organized that
demonstrates that the action is necessary to stabilize the
site, prevent further degradation, or achieve significant
risk reduction quickly." 55 Federal Register 8704 (March 8,
1990) (underlining added).
jrhe Streamlined Risk Assessment was developed in accordance with
this language. Consistent with the presumptive remedy guidance
for streamlining the RI/FS process, the RI focused on
characterizing areas where contaminant migration away from the
landfill was suspected.
In compliance with the NCP and EPA guidance, the Streamlined
Risk Assessment compares chemical concentrations found in various
media (for example: ground water; leachate exiting the landfill;
25
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surface soil, water, and leachate on the landfill surface; and
sediments and soils adjacent to the landfill) at the Site with
what are hereinafter referred to as "comparison numbers".20
These comparison numbers are established standards and criteria,
and calculated risk-based concentrations, that are generally
considered to be protective of human health and the
environment.21 These comparison numbers, with the exception of
the soil risk-based concentrations, have been established or
developed under federal or state laws.
The Streamlined Risk Assessment assumes a
commercial/industrial future use exposure scenario because this
is consistent with the Future Land Use Plan22 that the Tulalip
Tribes have developed for the Site.. A residential exposure
scenario was not used. The Tribes have designated the landfill
surface for recreation and possible economic development in the
form of commercial or light industrial use, and the surrounding
wetlands are designated for preservation as wetlands for
traditional hunting and fishing.
In addition to the completed Streamlined Risk Assessment,
EPA is currently preparing a comprehensive baseline risk
assessment for the off-source area of the Site. This
comprehensive baseline risk assessment will support decisions on
the need for response actions in the off-source area.
20 After evaluating public comments on the Proposed Plan, it is
apparent to EPA that some commentors were misled by EPA's use of the phrase
"screening criteria" in the Streamlined Risk Assessment to refer to standards,
criteria, and risk-based concentrations used in the streamlined Risk
Assessment. To clarify this issue, EPA is using the more accurate phrase
"comparison numbers" to refer to these standards, criteria, and risk-based
concentration. EPA notes that these comparison numbers have been selected for
use in the Streamlined Risk Assessment for the purpose of evaluating potential
risks posed by the Site. These comparison numbers are not necessarily ARARs.
21 Water quality standards and criteria are not necessarily
protective of wildlife or benthic organisms. EPA has been evaluating how to
produce water quality criteria that are protective of wildlife. The salient
issues in EPA's effort include evaluating bioaccumulation {from all routes of
exposure; food, sediment, water, etc.), bioconcentration (usually just
through exposure to water), and biomagnification (increasing tissue
concentrations with hierarchy in the food web) . Some of the first
contaminants to be evaluated in this manner include mercury and DDT, two
contaminants that are discharging from the Site. . Water quality standards and
criteria may be made more stringent in the future to address these concerns
(EPA notes, however, that ARARs for this interim remedial action are frozen
when this interim ROD is signed).
22 Big Flats Land Use Program, Tulalip Landfill Remedial Investigation
and Feasibility Study (July 10, 1994).
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6.1 HUMAN HEALTH EVALUATION
The human health evaluation in the Streamlined Risk
Assessment selects comparison numbers that represent
concentration levels that are considered to be protective of
people using the site for commercial/industrial purposes, and
then compares site-specific analytical data to these comparison
numbers. In general, comparison numbers include established
standards, criteria, and risk-based concentrations. Various
media on and adjacent to the landfill, including surface water,
ground water, surface soil, subsurface soil, leachate seeps,
surface sediment, and subsurface sediment, were sampled during
the Remedial Investigation. The Streamlined Risk Assessment
compares the sample results from these media to the comparison
numbers, and exceedences of the comparison numbers are summarized
and reported.
Human health comparison numbers for soils and sediments were
derived from two sources. A commercial/industrial scenario was
assumed for selection of soil and sediment comparison numbers
(comparison numbers for a recreational scenario were
unavailable). For each chemical, the lower of the two values
derived from the following sources was selected:
• EPA Region 3 risk-based concentration tables for industrial
exposures;
• Model Toxics Control Act (MTCA) Method C values for
industrial/commercial exposures (Chapter 173-340-740
Washington Administrative Code, Washington Department of
Ecology, 1995)
The Region 3 risk-based concentrations have been developed
by EPA using Risk Assessment.Guidance for Superfund (EPA, 1989)
algorithms and toxicity information"contained in both EPA's
Integrated Risk Information System (IRIS) database and Health
Effects Assessment Summary Tables (HEAST). Region 3 updates
these concentrations on a quarterly basis. The Region 3 risk-
based concentrations are considered to be protective of the
ingestion pathway, but are not considered to be protective of
other potential exposure routes such as inhalation, nor would
they be expected to prevent contaminant migration, such as
contaminants leaching from soil to ground water or surface water.
For surface water, leachate, and ground water that
discharges to surface water, comparison numbers were calculated
based on the indirect pathway of ingestion of seafood harvested
from surface water near the landfill, using:
• EPA Water Quality Standards: Establishment of Numeric
Criteria for Priority Toxic Pollutants; States' Compliance
Final Rule (EPA, 1992a).
27
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The comparison numbers were calculated based on a IxlCT6 cancer
risk, assuming consumption of 6.5 gm of fish per person per day.
This consumption rate was based on a national average; however,
this rate is likely below the fish consumption rate of Tulalip
Tribal members. A more realistic (i.e., higher) exposure
consumption rate for Tribal members will be developed and used in
the.comprehensive baseline risk assessment for the Site FS, which
will evaluate the need for additional response actions for the
off-source area. Human health comparison numbers for specific
contaminants in specific media are provided in Table 6-1.
Site-specific data were evaluated against the comparison
numbers. Chemicals that exceed the human health comparison
numbers were found in leachate exiting the perimeter landfill
berm through the leachate seeps, off-source surface sediments,
off-source subsurface sediments, off-source surface soils, and
off-source surface water in the tidal channels near leachate
seeps. Results of the comparison of Site data to human health
comparison numbers are shown in Table 6-2. This table includes
information on the frequency of exceedences in each medium.
Chemicals found in the leachate discharging from the
perimeter berm through the leachate seeps that were measured at
levels at least an order of magnitude (ten times) higher than the
human health comparison numbers include 4,4'-DDT, 4,4'-ODD,
4,4'DDE, aldrin, Aroclor-1016, Aroclor-1232, Aroclor-1254,
arsenic, benzo(a)anthracene, benzo(a)pyrene,
benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dieldrin,
indeno(1,2,3 -cd)pyrene, heptachlor, and heptachlor epoxide.
Chemicals exceeding the comparison numbers in soils and
sediments adjacent to the landfill surfa'ce include Aroclor 1242
and Aroclor 1248, arsenic, beryllium, heptachlor epoxide, and
polycyclic aromatic hydrocarbons (PAHs). Of these, arsenic had
the highest frequency of exceedance (98 to 100 per cent in soil
and sediment samples taken adjacent to the surface of the
landfill).
The RI/FS approach for evaluating Zone 2 ground water was to
measure ground water chemical concentrations at 13 perimeter
landfill berm wells. Based on this data from the berm wells, the
Respondents used a ground water modeling technique to predict the
degree of contaminant dilution that would be expected between the
berm wells and the location where Zone 2 ground water enters the
sloughs, which is where sediment-dwelling organisms would be
impacted and, according to State law, is where State water
quality standards must be applied. The results of the
Respondents' ground water modeling indicated that, in general,
one would expect contaminants in the berm wells to be diluted by
a factor of 5 to 9 by the time they reached the sloughs. This
reduction of average concentrations would result primarily from
28
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the contaminated ground water measured at the berms becoming
diluted from mixing with cleaner, uncontaminated ground water as
it moved toward the sloughs.
Assuming a concentration reduction at the low end of the
range predicted by the modeling, 5 times, arsenic would be
expected to exceed the human health comparison numbers at the
location where Zone 2 ground water enters the sloughs:
Chemical Frequency of Exceedances
Arsenic - total 17/73
Arsenic - dissolved 3/26
Assuming a concentration reduction at the high end of the
range predicted by the modeling, 9 times, arsenic still exceeds
the comparison numbers at the same frequency at the location
where Zone 2 ground water enters the sloughs:
Chemical Frequency of Exceedances
Arsenic - total 17/73
Arsenic - dissolved 3/26
Based on this evaluation, and if the concentration reduction
factor predicted by the modeling (5 to 9 times) between the berm
wells and the Zone 2/slough interface is assumed,23 arsenic
would be expected to exceed the human health comparison numbers
at the location where Zone 2 discharges to surface water.
Figure 6-1 is a map of the Site that shows sampling
locations of the most significant site data exceedences of the
human health comparison numbers. Sample data at the locations
shown in this Figure exceed the comparison numbers by at least an
'order of magnitude.
In addition to information regarding chemical contaminants
at the Site, EPA presented a summary of microbial data from
samples taken over a period of twenty years at and around the
Tulalip Site. See Streamlined Risk Assessment Appendix C.
23 EPA believes the Respondents' modeling effort is not sufficiently
conservative for a number of reasons. For example, the Respondents' model, a
model called Seep-W, assumed that the distance between the Zone 2 perimeter
berm wells and the sloughs was 300 feet. However, at some locations at the
Site this distance is significantly less than 300 feet (at the old barge canal
entrance, for example, the distance between the berm and the slough is 0
feet). Also, it is possible that Zone 2 leachate is surfacing in some of the
tidal channels in the wetlands between the landfill berm and the sloughs, for
which the model does not account. A more conservative modeling effort that
accounted for issues such as these may have resulted in a lower predicted
concentration reduction range than that predicted by the Respondents.
29
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Analyses of water samples taken from the Site indicate the
presence of opportunistic pathogens that are resistant to
antibiotics.
6.2 ECOLOGICAL EVALUATION
1 The ecological evaluation in the Streamlined Risk Assessment
selects or develops comparison numbers that represent
concentration levels considered to be protective of ecological
receptors, and then compares site-specific data results to the
comparison numbers. In general, comparison numbers include
established standards, criteria, and risk-based concentrations.
Various media on and near the landfill, including surface water,
ground water, surface soil, subsurface soil, leachate seeps,
surface sediment, and subsurface sediment, were sampled during
the Remedial Investigation. The Streamlined Risk Assessment
compares these sample results to the comparison numbers, and site
data exceedences of the comparison numbers are summarized and
reported.
The Streamlined Risk Assessment selects or develops
comparison numbers that are considered to be protective of
ecological receptors in the vicinity of Tulalip Landfill.
Comparison numbers for sediments are equivalent to the Washington
State Sediment Management Standards. The sediment comparison
numbers are dry-weight normalized Apparent Effects Threshold
(AET) concentrations which, if normalized for organic carbon, are
equivalent to the Sediment Management Standards. AETs are used
because Site data were reported on a dry weight basis, and, on a
dry-weight basis, AETs are equivalent to the Washington State
Sediment Standards (Chapter 173-204 WAC).
For surface water, groundwater, and leachate discharges, the
Streamlined Risk Assessment selects comparison numbers that are
considered protective of aquatic life.24 The federal criteria
developed under the authority of the Clean Water Act (CWA)
Section 304(a) are designed to protect all water bodies across
the nation. In addition, these or more stringent criteria have
been adopted as standards by Washington State.
For a given chemical, the most conservative of the State
standard or the federal criterion has been selected as the
comparison number. Application of freshwater versus marine
comparison numbers is based on the salinity of the receiving
water body and the types of plant and animal communities present.
24 Relatively recent changes to the National Toxics Rule were published
after development of the Streamlined Risk Assessment. However, these National
Toxics Rule changes would not have significantly changed the results of any
analyses, and would not have changed any conclusions, in the Streamlined Risk
Assessment.
30
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For example, data from on-source pooled water and leachate seep
SP-01 were compared to the more stringent of:
• Washington State acute and chronic fresh Water Quality
Standards (Ecology, 1992)
• . Federal acute and chronic freshwater Ambient Water Quality
Criteria (AWQC) (EPA, 1992b)
Data from off-source surface water, groundwater, and perimeter
berm leachate seeps discharging directly to off-source wetlands
were compared to the-more stringent of:
• Washington State acute and chronic marine Water Quality
Standards (Ecology, 1992)
• Federal acute and chronic marine Ambient Water Quality
Criteria (AWQC) (EPA, 1992b)
Comparison numbers used in the ecological evaluation for specific
contaminants in specific media are provided in Table 6-3.2S
The Streamlined Risk Assessment compared site data to the
comparison numbers. Chemicals exceed the comparison numbers in
samples taken from on-source surface water, on-source soil, Zone
1 groundwater, Zone 2 groundwater, leachate discharging through
the perimeter berm leachate seeps, off-source surface soil, off-
source subsurface soil, off-source surface water, off-source
surface sediment, and off-source subsurface sediment. Tables 6-4
and 6-5 summarize the chemicals found in these on-source and off-
source media at the Site that exceed the ecological comparison
numbers, and also provide information regarding the frequency of
the exceedences. .
Chemicals measured at levels at least ten times higher than
the ecological comparison numbers include pesticides (4,4'-DDT,
heptachlor epoxide, and aldrin), PCBs (Aroclor 1016 and Aroclor
1232) , copper, cyanide, endrin, lead, mercury, zinc, nickel,
chromium, acenaphthene, naphthalene, fluorene, and 2-
methylnaphthalene.
Chemicals found in off-source wetland soils near six of the
leachate seeps exceed comparison numbers, and chemicals exceed
comparison numbers in subsurface soils at five of the six
leachate seeps tested. Chemicals found in leachate exceeded
comparison numbers at least once in most of the eleven seeps that
were tested. Chemicals exceeding comparison numbers in Zone 1
25 AWQC calculations in the interim ROD Tables are based on a pH of 7.8
and hardness of 100 ppm CaCO3/ which are within ranges that have been measured
at the Site.
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ground water included total metals (copper, lead, nickel, and
zinc), and ammonia nitrogen, total cyanide, and heptachlor
epoxide.
The RI/FS approach for evaluating Zone 2 ground water was to
measure ground water chemical concentrations at 13 perimeter
landfill berm monitoring wells. Ground water samples taken
directly from the Zone 2 monitoring wells showed that total
metals (copper, lead, chromium, and nickel), total cyanide, and
ammonia nitrogen exceeded surface water comparison numbers in
many of the samples. Based on this data from the berm wells, the
Respondents used a ground water modeling technique to predict the
degree of contaminants dilution that would be expected between
the berm wells and the location where Zone 2 ground water enters
the sloughs, which according to State law is where State water
quality standards must be applied. The results of the
Respondents' ground water modeling indicated that, in general,
one would expect contaminants in the berm wells to be diluted by
a factor of 5 to 9 by the time they reached the sloughs.
Assuming-a concentration reduction at the low end of the range
predicted by the modeling, 5 times, the following contaminants
would be expected to exceed the ecological comparison numbers at
the location where Zone 2 ground water enters the sloughs:
Chemical Frequency of Exceedances
Cyanide - total 1/13
Nickel - total 7/73
Nickel - dissolved 2/26
Ammonia Nitrogen 73/73
Assuming*a concentration reduction at the high end of the
range predicted by the modeling, 9 times, the following
contaminants are predicted to exceed the ecological comparison
numbers at the location where Zone 2 ground water enters the
sloughs:
Chemical Frequency of Exceedances
Cyanide - total 1/13
Nickel - total 1/73
Ammonia nitrogen 73/73
Based on this- evaluation, and if the concentration reduction
factor predicted by the modeling (5 to 9 times) between the berm
wells and the Zone 2/slough interface is assumed,26 the
contaminants listed above would be expected to exceed the
ecological comparison numbers at the location where Zone 2
discharges to surface water.
26 See footnote 19.
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Figure 6-2 is a map of the Site that shows sampling
locations where the most significant site data exceedences of the
ecological comparison numbers occur. Sample data at the
locations shown in this Figure exceed the comparison numbers by
at least an order of magnitude.
6.3, ASSESSMENT OF SITE
The results of the Streamlined Risk Assessment indicate that
there are a significant number of exceedances of human health and
ecological comparison numbers in most of the media at the Site.
Exceedences were found in leachate, surface water, ground water,
soils, and sediments at the Site. These exceedances indicate the
potential for adverse effects to people that use the Site, and to
animals and plants that live on or near the landfill and come
into contact with these media. The RI data establishes a clear
link between contamination leaving the landfill and that found in
adjacent areas. Many of the chemicals that exceeded comparison
numbers in soil and sediment samples taken near the landfill
leachate seeps were also detected in leachate seeping from the
landfill surface and berm. EPA does not consider ecological
risks as having adverse implications only for the environment.
Ecological risks also impact human health.
Site data that exceed the chemical comparison numbers, which
are considered to be protective of plants, mammals, and aquatic
organisms, indicate that many plants and organisms may be at risk
from exposure to hazardous substances at the Site. See
Streamlined Risk Assessment pages 4-9 and 4-10, and Appendix A.
Soil concentrations that are toxic to plant life indicate that
the more sensitive plant species, and animals such as field mice
and waterfowl that feed on them, may be adversely affected.
Increased mortality to plants also indicates that the natural
cycle of nutrients within the wetland may be altered. Such
exceedances may present threats not only to these types of plants
and organisms but also animal predators higher on the food chain,
such as hawks, eagles, and salmon. Some chemicals, such as DDT
and PCBs, tend to increase in concentration as they move up the
food chain, and may represent higher risks for predators. For
example, shrews may become contaminated from ingesting earthworms
that live in contaminated soils. If field mice and shrews die as
a result of the contamination, then predators lose them as a food
source. If the field mice and shrews accumulate contaminants but
don't die, their predators may be at risk from elevated
contaminant concentrations in their food supply.
The presence of these chemicals at concentrations above the
comparison numbers indicates that there are releases of hazardous
substances that pose actual or potential threats to animal and
plant life in the wetland areas around Tulalip Landfill. In
addition, data collected during the RI show the presence of
chemicals of concern (for example, cadmium, chromium, and nickel)
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in sculpin (a species of fish) found in the tributaries
surrounding the Site. Wetlands are considered sensitive habitats
and are protected under the Clean Water Act. They have attained
national recognition as critical areas for important ecological
functions such as avian roosting, feeding, and breeding; fish and
invertebrate nurseries; nutrient import and export; flood
control; and sediment trapping. Wetland areas serve as critical
habitat to animals during the sensitive life-stages of
reproduction and rearing. Many kinds of birds such as waterfowl,
shorebirds, eagles and falcons use the wetland areas surrounding
Tulalip Landfill for feeding and rearing of young. (Estuarine
and marine fish and invertebrate species use wetland areas for
reproduction and rearing of juveniles; therefore, more sensitive
life-stages are likely to be present during certain periods of
the year). It is important to ensure these sensitive life-stages
are protected from stress in the form of chemical contamination
or deterioration of habitat quality.
In addition to the importance of protecting the estuary
wetlands from potentially harmful concentrations of chemicals
that exceed the comparison numbers, it is also important to
reduce the total loading of contaminants from the landfill to the
estuary. When contaminants leave the landfill they enter the
nearby ecosystems which include wetlands and sloughs.
Contaminants in the leachate seeps (accounting for approximately
5-35% of the leachate leaving the landfill) are also found in the
media surrounding the landfill, strongly indicating a transport
pathway from the landfill to the nearby ecosystems. The
strongest indication of movement of bioaccumulative contaminants
from the seeps to surrounding media comes from leachate seep
locations SP08 (for DDT) and SP09 (for PCBs).
Similarly, contaminants found in the ground water within the
landfill are most likely moving with the ground water into the
surrounding ecosystems (estimated as about 65% to 95% of the
total leachate transport). Like the leachate seep contaminants,
these ground water contaminants can accumulate in sediments as
the ground water contacts the nearby surface waters (tributaries,
tidal creeks, and the sloughs). Based on the exceedances of
comparison numbers in Zone 2 ground water in the berm wells and
predicted through ground water modeling at the sloughs, it is
appropriate to conclude that discharges from the landfill are
resulting in exceedances of human health and ecological
comparison numbers at the location where Zone 2 ground water
discharges to surface water, which represents a potential threat
to human health and the environment.
Based on the RI ground water modeling, chemicals of concern
at the location where Zone 2 ground water discharges to the
sloughs include arsenic (for human health); and cyanide, nickel,
and ammonia (for ecological receptors). EPA notes that ammonia
nitrogen (i.e., ammonia) exceeds comparison numbers in all
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samples taken at the high end of the predicted concentration
reduction range (73 of 73). Based on the loading rate estimates
provided in RI Table 5-14, the yearly discharge rate of ammonia
from the entire Site would be approximately 2971 Ibs., or about
1.5 tons. Approximately 65% to 95% of the total leachate at the
Site discharges through Zone 2, so the contribution from the Zone
2 wells would be in range of 1931 Ibs. to 2822 Ibs. (1 to 1.5
tons) per year.
Although dilution of dissolved or suspended material and
contaminants will undoubtedly occur as leachate or ground water
moves away from the landfill, there is significant potential for
several classes of contaminants to associate with organic
material and other particles, accumulate in sediments, and become
incorporated into the food webs in the ecosystems surrounding the
landfill. Of particular concern, because of extremely well-
documented information elsewhere, are persistent and
bioaccumulative contaminants such as DDT (and other historical
pesticides), PCBs, and metals.
The predicted toxicity of contaminants in the leachate seeps
and groundwater has been evaluated using standard approaches
(comparison with available standards, criteria, risk-based
levels, etc.). Existing data show clear indications of toxicity
from landfill sources. At leachate seeps in particular, DDT and
two PCB Aroclors (1016 and 1232) had exceedences of 13-49, 16-40,
and 33-194 times the ecological water quality criterion,
respectively. These consistent, high level exceedences
underscore the concern that the leachate seeps represent an
ongoing source that loads these persistent and bioaccumulative
contaminants into the surrounding ecosystems. Of similar concern
is mercury, which had concentrations in the leachate up to 15
times the water quality criterion. Even though these
concentrations are likely to decrease with distance from the seep
source, constant loadings could maintain the presence of these
compounds in the surrounding off-source media.
One reason the landfill poses a problem for its surroundings
is its relatively large size. The landfill perimeter
(approximately 5,300 feet) fronts over 2 miles of off-source,
ecologically significant wetlands. The landfill contributes a
significant amount of leachate to the estuary, estimated between
26.3 to 188.1 million gallons each year.
For information regarding potential limitations regarding
the data use and interpretation, see Streamlined Risk Assessment
Section 4.6 - Uncertainty Analysis. Samples taken for the
Remedial Investigation show that "reference" wetland areas
located a short distance from the landfill have elevated levels
of man-made chemicals. EPA's interpretation of these results is
that this contamination in off-Site reference areas suggests that
the wetlands and sloughs in the vicinity of the landfill are
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already at risk from contaminant loading, from sources that may
include the landfill. Based on information gathered by EPA over
the years at the Site, it is reasonable to conclude that the
Tulalip Landfill is a chronic source of contamination to the
surrounding estuary. Containment of the landfill source area is
expected to reduce chemical loadings to off-source areas.
The nature and extent of contamination at Tulalip Landfill
and the associated potential risks as determined from the
Streamlined Risk Assessment require remedial action to be taken
at the Site. Comparison of the measured Site chemical
concentrations to the human health risk-based and ecological
effects-based standards and criteria established under other
environmental laws, and risk-based chemical concentrations,
reveals significant potential risks to humans and the
environment. Based on the RI/FS and findings in the Streamlined
Risk Assessment, EPA finds that actual or threatened releases of
hazardous substances from the Site, if not addressed by the
selected alternative, may present an imminent and substantial
endangerment to public health, welfare, or the environment. The
qualitative risk information provided in the Streamlined Risk
Assessment demonstrates that remedial action is necessary to
stabilize the site and to prevent further degradation of off-
source areas as a result of chemical discharges from the Site.
Based on the microbial data collected from the Site, EPA
concluded in the Streamlined Risk Assessment that "microbial
contamination at the site may pose a potential risk to humans."
7.0 CLEANUP OBJECTIVES FOR THE INTERIM REMEDIAL ACTION
Based on the results of the RI and the Streamlined Risk
Assessment, the extent of contamination at the Site includes the
following: _
• the waste placed in the landfill, including part or all of
the landfill berm; Zone 2 ground water within the waste
mass;
• leachate exiting the berm through seeps and discharging to
the wetlands and tidal channels adjacent to the landfill;
• the landfill surface, including surface soils, pooled water
on the landfill surface and at least one leachate seep on
the landfill surface;
• Zone 2 ground water beneath the waste mass that moves
beneath the adjacent wetlands and discharges directly into
the sloughs and possibly the tidal channels;
• sediments and soils adjacent to the landfill; and
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• fish that live near the landfill.
The purpose of establishing Remedial Action Objectives
(RAOs) is to help ensure that the selected remedial action will
be protective of human health and the environment by effectively
containing waste at the Site and to minimizing exposure of humans
and-ecological receptors to Site contaminants. The RAOs for the
interim remedial action are:
Zone 1 leachate: Eliminate migration of leachate that
exceeds surface water ARARs from, through, and under the
source area berm;
Soil/landfill contents/on-source surface water: Prevent
direct contact with, and ingestion of, landfill contents,
contaminated soils, and contaminated surface water on the
landfill surface;
Minimize infiltration: Minimize infiltration into the
landfill wastes and resulting contaminant leaching to ground
water.27
Zone 2 ground water: Minimize migration of contaminated
ground water at levels exceeding surface water ARARs, and
prevent use of contaminated ground water;
Stojrmwater_ runoff and erosion: Prevent detrimental impact
to adjacent off-source wetlands and surface water bodies due
to stormwater runoff from the landfill cap surface;
Landfill gas: Prevent inhalation and release of landfill
gas exceeding ambient air standards established by the Puget
Sound Air Pollution Control Authority (PSAPCA). Manage
landfill gas to prevent stress on a cap system;
Wetlands: Minimize loss of off-source wetlands, and
mitigate for any destruction of or damage to off-source
wetlands from the remedial action;
Future land use: Provide final surface conditions suitable
for all season subsistence (i.e., hunting and fishing),
recreational, and light industrial and commercial use.
The point of compliance for Zone 1 ground water (i.e., the
leachate seeps) shall be the point at which leachate exits the
exterior face of the perimeter landfill berm. The point of
27 Inclusion of this RAO is recommended by EPA guidance. See
Presumptive Remedy for CERCLA Municipal Landfill Sites (EPA 540-F-93-035,
September 1993)', page 5.
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compliance for Zone 2 ground water shall be the location where
Zone 2 ground water discharges to surface water.
7.1 SUMMARY OF MAJOR APPLICABLE REQUIREMENTS
This section and the following section (Section 7.2)
summarize some of the major applicable or relevant and
appropriate requirements ("ARARs") that have been identified as
part of the analysis of the proposed alternatives. This section
summarizes requirements that are "applicable" to the interim
remedial action, and Section 7.2 summarizes requirements that are
"relevant and appropriate." A more detailed discussion and
analysis of these and other ARARs, including explanation of why
these requirements are applicable or relevant and appropriate, is
provided in Section 11.2 of this ROD. However, these ARARs are
presented here in summary fashion in.order to assist the reader
with the discussions contained in the "Description of
Alternatives" and the "Summary of the Comparative Analysis of
Alternatives" sections of this interim action ROD. The following
requirements are applicable to the interim remedial action:
Section 402 of the Clean Water Act ("CWA") -- 33 U.S.C.
§ 1342
Normally, any sort of action that results in dredging or
filling wetlands is governed by Section 404, not 402, of the CWA.
However, in November 1984, the U.S. Army Corps of Engineers
informed the Tulalip Tribes of the Corps' decision that the
landfill capping activities that the Tribes were undertaking in
the 1980's would fall under the authority of Section 402 of the
CWA, not Section 404. Thus, for the on-source area of the
landfill, Section 402 is the ARAR under the CWA, not Section 404.
Section 402 of the CWA established the NPDES permit program,
which governs direct discharges from point sources. The NPDES
permit regulations contain provisions for discharge limitations,
monitoring requirements, and best management practices. Because
this interim action is being conducted entirely on-site, Section
121 (e) of CERCLA does not require that a NPDES permit be issued
to cover these on-site discharges. However, this interim action
will meet all substantive requirements of the NPDES permit
program for any on-site discharges.
Section 404 of the Clean Water Act -- 33 U.S.C. § 1344
Section 404 of the CWA regulates the discharge of fill
material into the waters of the U.S., including wetlands.
Section 404 is relevant and appropriate for the off-source areas
of the Site. The guidelines for this program are set forth in 33
C.F.R. Parts 320 through 330 and 40 C.F.R. Part 230, and are
established to ensure that proposed discharges are evaluated with
respect to impacts on aquatic ecosystems.
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Clean Air Act (42 U.S.C. §§ 7401 et seq.) -- National
Primary and Secondary Ambient Air Quality Standards, 40
C.F.R. Part 50-
These regulations govern emissions of particulates and
certain priority pollutants to the air from on-site sources.
Remedial actions that would result in air emissions will be
designed to meet federal air quality standards.
7.2 SUMMARY OF MAJOR RELEVANT AND APPROPRIATE REQUIREMENTS
The following summarizes some of the major requirements that
are relevant and appropriate for the interim remedial action:
Federal Water Pollution Control Act/Clean Water Act --
33 U.S.C. §S 1251-1376; 40 C.F.R Parts 100-149
These statutes and their implementing regulations govern
discharges of water and wastewater to sewers, surface water, and
site runoff that is directed to a water body subject to the Acts.
They establish point source standards for discharges into surface
water bodies under the National Pollutant Discharge Elimination
System ("NPDES"). They also establish ambient water quality
criteria ("AWQC") for the protection of aquatic organisms and
human health.
Washington _State- Model Toxics__ControJL Act ("MTCA") - -
RCW Chapter 70.105D; WAC Chapter 173-34Q
The State of Washington MTCA contains numerical cleanup
standards for groundwater, surface water, soils, air, and
sediments. The MTCA regulations that pertain to the Tulalip
Landfill are the groundwater and surface water cleanup standards
contained in WAC 173-340-720 and -730. These regulations are
relevant and appropriate for groundwater and "surface waters of
the state" that are affected or potentially affected by a release
of a hazardous substance to those waters.
State of Washington Water Pollution Control Act/Water
Resources Act -- Chapters 90.48 and 90.54 of the
Revised Code of Washington ("RCW"); Water Quality
Standards for Surface Waters -- Chapter 173-201A -WAG
These statutes, through their implementing regulations,
require the use of all known available and reasonable
technologies in the treatment of wastewater prior to a release or
discharge of such wastewater into waters of the State. These
statutes do not contain any numerical criteria or standards.
However, the WAC 173-201A regulations implement the federal
requirement that the state develop a water quality control plan.
These regulations contain both narrative and quantitative
limitations for protection of surface waters by regulating
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discharges to sewers and surface waters, and establish discharge
limits for water quality parameters and toxic substances.
Federal Solid Waste Municipal Landfill Requirements --40
C.F.R. Part 258
. These relevant and appropriate regulations require that
landfills be closed to meet certain performance standards
governing surface slopes, landfill cover construction, and
revegetation.
Minimal Functional Standards ("MFS") for Solid Waste
Handling. WAC Chapter 173-304
These relevant and appropriate regulations require that
landfills be closed to meet certain performance standards
governing surface slopes, landfill cover construction, and
revegetation.
Washington State Clean Air Act (R.C.W. 70.94); Puget Sound
Air Pollution Control Authority ("PSAPCA") Regulations I and
III
These regulations govern emissions of particulates and
certain priority pollutants to the air from on-site sources. The
state Clean Air Act and PSAPCA regulations are relevant and
appropriate requirements which would ensure that emissions from
the interim remedial action will be performed in compliance with
the substantive requirements of a PSAPCA permit. However, on-
site actions will not require a PSAPCA permit.
The PSAPCA Guidelines For Acceptable Ambient Levels ("AALs")
are not ARARs because they are non-promulgated guidance, but
instead are guidelines "to be considered" ("TBC") when
implementing the selected remedy. The AAL guidelines specify
that actions producing air emissions must meet the guidelines.
They are used to help implement PSAPCA Regulation III, which
governs releases of toxic air pollutants.
8.0 DESCRIPTION OF ALTERNATIVES
The Source Area Containment Feasibility Study (FS)
identified and evaluated containment alternatives that could be
used to address threats and potential threats posed by the Site
for the Interim Remedial Action. In addition, the Respondents
have submitted several alternatives that were not included' in the
FS and which are discussed below. As discussed in Section 4.0,
EPA has prepared the Feasibility Study Analysis for CERCLA
Municipal Landfill Sites, September 1993, which provides an
evaluation of 30 CERCLA landfill FS reports, and has been
included in the Administrative Record for this interim ROD. The
Feasibility Study Analysis summarizes the initial identification
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and screening technologies used in the selection of landfill
remedies at the identified CERCLA sites as further support for
the identification 'and screening of technologies and development
of alternatives in the Source Area Containment FS for the Tulalip
Landfill.
Common Elements
With the exception of the "No Action" alternative, all of
the alternatives would include some form of:
• institutional controls, such as land use restrictions that
limit or prohibit development or activities conducted on the
Site so as to not interfere with performance of the selected
remedy, and to prohibit activities that are not protective
of human health and the environment (e.g., prohibit any
drilling or other excavation through any layer of the cover
system that may interfere with the performance of the
remedy, and set weight restrictions and weight distribution
restrictions for loads that can be placed on the cover)/
• a monitoring plan to measure the effectiveness of the remedy
and ensure that the remedy remains protective of human
health and the environment; and
• a plan for conducting operation and maintenance (O&M).
All "present worth" costs shown below include capital costs and
operation and maintenance over a 30-year period, calculated with
a discount rate of 5%. Actual costs are predicted to fall within
a range of +50 per cent to -30 per cent of cost estimates.
For the geosynthetic cover alternatives that don't include
ground water extraction from the deeper Zone 2 aquifer, a common
element is that no action would be taken to collect or treat the
ground water in Zone 2. For all of the capping alternatives,
"clean" runoff water would be discharged to the tidal channels or
sloughs surrounding the landfill at a rate and in a manner that
will prevent harm to the off-source wetlands.
The alternatives evaluated for addressing the environmental
problems are:
8.1 ALTERNATIVE 1 - NO ACTION
Annual Monitoring Cost: $63,000
Total Cost Estimate: $1,030,000
The Superfund program requires that the "no action"
alternative be evaluated at every site to establish a baseline
for comparison. Under this alternative, EPA would take no
further action at the Site to prevent exposure to contaminants,
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or to prevent the migration of contaminants. The cost estimate
above assumes that there would be some monitoring of the leachate
seeps and ground water at the Site.
8.2 ALTERNATIVE 2 - ACTIVE LEACHATE SEEP INTERCEPTION AND
TREATMENT
Construction Cost: $2,500,000
Annual O&M Cost: $ 220,000
Total Cost Estimate: $5,900,000
Estimated Construction Timeframe: 2 years
Leachate in the Zone 1 ground water that is migrating to the
surface through the perimeter landfill berm would be collected
and treated. To intercept the leachate, a drainage trench would
be built around the landfill. The trench would extend from the
surface of the landfill near the perimeter to the bottom of the
waste. The trench would be filled with a porous material to
collect leachate before it discharges to the surrounding
wetlands.
Approximately-24 extraction wells installed around the
perimeter within the trench would extract the leachate. The
leachate would either be sent to a nearby wastewater treatment
plant, or an on-site treatment system would be built. If an on-
site treatment system were built, the costs would be
significantly higher than the estimate provided above. It is not
anticipated that off-source wetlands would be adversely impacted
by construction of this alternative.
8.3 ALTERNATIVE 2b - LEACHATE COLLECTION WITH TREATMENT BERM
Alternative 2b was developed by the Respondents and
submitted to EPA for consideration subsequent to approval by EPA
of the Source Area Containment Feasibility Study. The
Respondents' submittal describing this alternative (Development
and Evaluation of the Treatment Berm Alternative, June 30, 1995)
is included in the administrative record for this interim remedy.
Respondents Construction Cost: $11,300,000
Respondents Annual O&M Cost: $ 129,000
Respondents Total Cost Estimate: $13,300,000
EPA Construction Cost: $18,000,000
EPA Annual O&M Cost: $ 179,000
EPA Total Cost Estimate: $21,300,000
Estimated Construction Timeframe: 2 years
This alternative is similar to Alternative 2, except that it
includes additional collection trenches across the center of the
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landfill, and it would pass the landfill leachate through two
earthen berras before releasing the leachate to the sloughs. One
of these berms would be located in the mouth of the old barge
canal, and the other would be constructed on the southern edge of
the landfill. The Respondents predict that water leaving the
berms would meet water quality cleanup goals as a result of
dilution (leachate mixing with slough water), and natural
treatment processes such as chemical and biological degradation
of contaminants within the berm.
In addition to the perimeter collection system in
Alternative 2, collection trenches would also be constructed
transecting the landfill surface. The purpose of the additional
trenches is to reduce the leachate mound in the center of the
landfill, thereby reducing the flow of leachate down, into the
deeper Zone 2 ground water and out into the sloughs.
The proposed collection system and berm treatment system are
unproven technologies that have never been used to control .
leachate generated by a landfill like Tulalip Landfill. Based on
EPA' s review of information submitted by the Respondents on this
alternative, EPA concluded that the Respondents significantly
underestimated the cost of this alternative, given the level of
uncertainty involved with the proposed technology. EPA has
developed a separate cost estimate for this alternative. Both
cost estimates are provided above for comparison.
A traditional, on-site treatment system could also be built
to accept the leachate. If an on-site treatment system were
built, the costs would be significantly higher than the estimate
provided above. The Respondents estimate that 2.8 acres of off-
source wetlands would be adversely impacted or lost in order to
construct the proposed treatment berms.
8.4 ALTERNATIVE 2b(ii) - LEACHATE SEEP COLLECTION WITH DISCHARGE
TO PUBLICLY OWNED TREATMENT WORKS (POTW)
At the October 3, 1995, public meeting, a variation of
Alternative 2b was described. In a submittal dated October 24,
1995, more detailed information regarding this variation of
Alternative 2b was provided to EPA by the Respondents for
consideration during the public comment period on the Proposed
Plan. This submittal is available in the administrative record
for this interim remedy.
Respondents Construction Cost: . $ 5,900,000
Respondents Annual O&M Cost: $ 386,000
Respondents Total Cost Estimate: $11,800,000
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EPA Construction Cost: $13,600,000
EPA Annual O&M Cost: $ 465,000
EPA Total Cost Estimate: $20,800,000
Estimated Construction Timeframe: 2 years
. Alternative 2b(ii) uses the same basic leachate collection
system as Alternative 2b, with some modifications,28 but instead
of sending the leachate through treatment berms, the leachate
would be sent to an off-site sewage treatment plant, also
commonly referred to as a Publicly Owned Treatment Works (POTW).
The submittal proposes to collect approximately 58 million
gallons of leachate per year and send it to either the Marysville
or Everett POTW, where it would be treated along with other
effluent streams received by the POTW. For purposes of
clarifying discussion in this Record of Decision, to
differentiate this version of alternative 2b from the Treatment
Berm version described above, the POTW discharge version shall be
referred to henceforth as "Alternative 2b(ii) - Leachate Seep
Collection with Discharge to POTW". It is not anticipated that
any off-source wetlands would be adversely impacted by
construction of this alternative.
8.5 ALTERNATIVE 3 - LEACHATE SEEP AND GROUND WATER COLLECTION
AND TREATMENT
Construction Cost: $12,400,000
Annual O&M Cost: $ 620,000
Total Cost Estimate: $22,000,000
Estimated Construction Timeframe: 2 years
Shallow leachate and deeper, contaminated ground water from
the landfill would be collected and treated. To minimize the
leachate and ground water migrating away from the landfill, and
to minimize the amount of uncontaminated ground water that could
be pulled in by the pumping system, a "slurry wall" would be
constructed underground around the waste. A slurry wall is an
wall of low permeability made of clay that is constructed inside
a deep, narrow trench. The slurry wall would completely surround
the on-source area of the Site. Approximately 24 extraction
wells would be installed inside the slurry wall to extract the
leachate.
The leachate would be sent to a POTW, or an on-site
treatment system would be built. If an on-site treatment system
needed to be built, the costs would be significantly higher than
28 The concept for the leachate collection system remains basically the
same as with Alternative 2b, with the addition of some pumps to help move the
leachate through the collection trenches, and some additional sumps.
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the estimate provided above. It is not anticipated that any off-
source wetlands would be adversely impacted by construction of
this alternative.
8 .6 ALTERNATIVE 4a - SOIL COVER WITH PASSIVE DRAINAGE
Construction Cost: $19,500,000
Annual O&M Cost: $ 170,000
Total Cost Estimate: $22,100,000
Estimated Construction Timeframe: 2 years
A low hill with a minimum 2% slope would be constructed on
the landfill, which would allow rain water to run off the cover
under the force of gravity ("passive drainage"). The landfill
would be covered with approximately two feet of clay, which would
reduce the amount of rainwater going into the landfill. A
protective layer of soil would be placed over the clay layer to
protect it.
Ground water modeling conducted by the Respondents during
the RI indicates that this alternative would'reduce, but not
eliminate, the perimeter leachate seeps. It would also reduce
the amount of contaminated deeper ground water migrating into the
sloughs, but to a lesser extent than the geosynthetic cover
alternatives. The cover would prevent contact with contaminants
on the landfill surface. In constructing this alternative,
approximately 1.7 acres of off-source wetlands would be adversely
impacted or lost.
8.7 ALTERNATIVE 4b - GEOSYNTHETIC COVER WITH ACTIVE DRAINAGE
Respondents Construction Cost; $15,600,000
Respondents Annual O&M Cost: H? 190,000
Respondents Total Cost Estimate: $18,600,000
+ EPA Gas Treatment Contingency: $ 2,700,000
EPA Total Cost Estimate: $21,300,000
Estimated Construction Timeframe^2 years
The Site would be graded into a "waffle" pattern, with rain
water flowing into many depressions on the surface of the cover.
A geosynthetic cover would be installed over this waffle pattern.
This geosynthetic cover would basically consist of a single
barrier layer, which would be either a type of thick plastic, or
a manufactured clay-type sheet product. Twelve inches of clean
topsoil would be placed on top of the geosynthetic cover and
planted with vegetation to reduce erosion and protect the low
permeability layer.
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This alternative is less expensive in the short term because
the landfill would remain relatively flat (i.e. fill material
would not be brought on-site to create a low hill with a 2% slope
that would passively drain rain water off of the cover). Rather,
a system of pipes and pumps would be installed to pump rain water
out of the depressions ("active drainage").
EPA's higher cost estimate for this alternative reflects the
possibility that a landfill gas treatment system may be necessary
under this type of cover, which is less permeable than a soil
cover.
Based on the results of groundwater modeling conducted
during the RI/FS, this alternative would substantially reduce
infiltration of rain water through the waste, thus minimizing the
potential for generation and migration of new leachate. This
alternative would be expected to eliminate the perimeter berm
leachate seeps within two years, and would substantially reduce
migration of leachate into Zone 2. The cover would also prevent
contact with contaminants on the landfill surface. In
constructing this alternative, approximately 1.7 acres of off-
source wetlands would be adversely impacted or lost.
8.8 ALTERNATIVE 4c - GEOSYNTHETIC COVER WITH PASSIVE DRAINAGE
Respondents Construction Cost: $19,800,000
Respondents Annual O&M Cost: $ 170,000
Respondents Total Cost Estimate: $22,400,000
+ EPA Gas Treatment Contingency: $ 2,700,000
EPA Total Cost Estimate: $25,100,000
Estimated Construction Timeframe: 2 years
This alternative would include the same actions as
Alternative 4b but with passive drainage. The Site would be
graded, and fill would be brought to the Site to construct a low
hill with a minimum of a two percent slope, over which a
geosynthetic cover would be installed. This geosynthetic cover
would basically consist of a single barrier layer, which would be
either a type of thick plastic, or a manufactured clay-type sheet
product. Twelve inches of clean topsoil would be placed on top
of the geosynthetic cover and planted with vegetation to reduce
erosion and protect the low permeability layer. EPA's higher
cost estimate for this alternative reflects the possibility that
a landfill gas treatment system may be necessary.
This alternative is expected to minimize the infiltration of
surface water into the waste contents of the landfill. The
effect of the low permeability cover will be to significantly
decrease the levels of contaminated leachate within the landfill
waste. As a result, the low permeability cover will eliminate
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the release of leachate from seeps at the surface and the
perimeter of the landfill, and minimize the migration of
contaminated water from the landfill through the deeper Zone 2
ground water aquifer to the sloughs.
Based on the results of groundwater modeling conducted
during the RI/FS, this alternative would minimize infiltration of
rain water through the waste, thus minimizing the potential for
generation and migration of new leachate. This alternative would
be expected to eliminate the perimeter berm leachate seeps within
two years, and would minimize migration of leachate into Zone 2.
The cover would also prevent contact with contaminants on the
landfill surface. In constructing this alternative,
approximately 1.7 acres of off-source wetlands would be adversely
impacted or lost.
8.9 ALTERNATIVE 4d - COMPOSITE COVER WITH PASSIVE DRAINAGE
Respondents Construction Cost: $24,000,000
Respondents Annual O&M Cost: $ 200,000
Respondents Total Cost Estimate: $27,100,000
+ EPA Gas Treatment Contingency: $ 2,700,000
EPA Total Cost Estimate: $29,800,000
Estimated Construction Timeframe: 2 years
A composite cover has two low permeability layers instead of
just one. Usually a composite cover combines a thick plastic
liner with a layer of clay. Composite covers usually develop
fewer leaks over time, because one layer can fail and the second
layer will still be effective in minimizing infiltration.
Although composite covers generally perform better over time than
single-layer covers, they are more expensive'.
Based on the results of groundwater modeling conducted
during the RI/FS, this alternative would minimize infiltration of
rain water through the waste, thus minimizing the potential for
generation and migration of new leachate. This alternative would
be expected to eliminate the perimeter berm leachate seeps within
two years, and would minimize migration of leachate into Zone 2.
The cover would also prevent contact with contaminants on the
landfill surface. EPA's higher cost estimate for this
alternative reflects the possibility that a landfill gas
treatment system may be necessary. In constructing this
alternative, approximately 1.7 acres of off-source wetlands would
be adversely impacted or lost.
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8.10 ALTERNATIVE 5: GEOSYNTHETIC COVER WITH LEACHATE SEEP
CONTROL
Respondents Construction Cost: $22,200,000
Respondents Annual O&M Cost: $ 220,000
Respondents Total Cost Estimate: $25,600,000
+ EPA Gas Treatment Contingency: $ 2,700,000
EPA Total Cost Estimate: $28,300,000
Estimated Construction Titneframe: 2 years
The Site would be graded, and fill would be brought to the
Site to construct a low hill with a minimum of a two percent
slope, over which a geosynthetic cover would be installed. This
geosynthetic cover would basically consist of a single barrier
layer, which would be either a type of thick plastic, or a
manufactured clay-type sheet product. Twelve inches of clean
topsoil would be placed on top of the geosynthetic cover and
planted with vegetation to reduce erosion and protect the low
permeability layer. An active perimeter leachate seep
interception system, such as the one described in alternative 2
above, would be installed.
Based on the results of groundwater modeling conducted
during the RI/FS, this alternative would minimize infiltration of
rain water through the waste, thus minimizing the potential for
generation and migration of new leachate. This alternative would
be expected to eliminate the perimeter berm leachate seeps soon
after construction, and would minimize migration of leachate into
Zone 2. The cover would also prevent contact with contaminants
on the landfill surface. EPA's higher cost estimate for this
alternative reflects the possibility that a landfill gas
treatment system may be necessary. In constructing this
alternative, approximately 1.7 acres of off-source wetlands would
be adversely impacted or lost.
8.11 ALTERNATIVE 6 - GEOSYNTHETIC COVER WITH LEACHATE SEEP AND
GROUND WATER CONTROLS
Respondents Construction Cost: $31,700,000
Respondents Annual O&M Cost: $ 280,000
Respondents Total Cost Estimate: $36,000,000
+ EPA Gas Treatment Contingency: $ 2,700,000
EPA Total Cost Estimate: $38,700,000
Estimated Construction Timeframe: 2 years
In addition to the actions discussed in Alternative 5, this
alternative would also include ground water collection and
treatment. The ground water would be collected by constructing a
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slurry wall around the Site, and approximately 24 extraction
wells would extract the leachate.
This alternative would practically guarantee the elimination
of the perimeter berm leachate seeps soon after construction, and
would minimize the generation and migration of leachate in the
deeper ground water to the sloughs. The cover would prevent
contact with contaminants on the landfill surface. In
constructing this alternative, approximately 1.7 acres of off-
source wetlands would be adversely impacted or lost.
8.12 OTHER ALTERNATIVES
In addition to the alternatives described above, the
Respondents proposed two alternatives which EPA considered and
appropriately directed the Respondents to exclude from the
feasibility study because they are not protective of human health
and the environment and do not attain potential applicable or
relevant and appropriate requirements (ARARs). One of these
alternatives involved placement of a "leachate seep cover" that
would cover the landfill berm and would divert the shallow
leachate exiting the berm into the deeper ground water zone,
where it would migrate to the sloughs. The other alternative
involves "passive leachate seep interception", which was a series
of 120 drains that would be installed in the waste, and would
also theoretically divert the shallow leachate into the deeper
ground water, where it would migrate to the sloughs.
Neither of these alternatives would be protective because
they would not effectively contain the landfill contaminants.
They would allow all of the leachate currently being generated at
the Site to continue to discharge into the surrounding
environment. They would only change the route the leachate takes
to leave the landfill. Because they would not reduce the total
loading of contaminants to the off-source area, they do not meet
the NCP remedy evaluation criterion for "Overall Protection of
Human_Health and the Environment." These alternatives would not
meet the criterion for "Compliance with ARARs""because they would
be expected to worsen existing AWQC exceedences where Zone 2
ground water enters the sloughs. They would not meet "Short-Term
Effectiveness" because they would do nothing to reduce total
loading of the landfill contaminants to the environment. These
alternatives do not meet, or score relatively poorly on, the
"Long-Term Effectiveness and Permanence," "Reduction of Toxicity,
Mobility, or Volume through Treatment," and "Implementability"
criteria. EPA is also seriously concerned that these
alternatives would not function as designed in the field, and the
Respondents have not brought other landfills where such
technologies have been successfully implemented to EPA's
attention.
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These alternatives are inconsistent with the NCP and with
EPA guidance which states that containment of contaminants is
appropriate at landfill sites such as the Tulalip Landfill. The
alternatives would re-direct visible leachate exiting the
landfill berm down into the aquifer where it would be free to
enter the environment unseen via the sloughs. These alternatives
also, are of questionable cost-effectiveness because in EPA's view
they offer no real environmental benefit, but their
implementation would require substantial monetary expenditures.
The Respondents' proposal for inclusion of these unsuitable
alternatives in the Source Area Containment FS was the subject of
a formal dispute resolution process under the RI/FS
Administrative Order on Consent (AOC). A summary of this dispute
is provided in Section 2 of this ROD. Correspondence and EPA's
final determination regarding this dispute is included in the
Administrative Record for this interim ROD.
9.0 SUMMARY OF THE COMPARATIVE ANALYSIS OF
ALTERNATIVES
As required by the National Contingency Plan (NCP), EPA used
the nine NCP criteria summarized below to evaluate and compare
alternatives. An alternative must meet both criteria 1 and 2,
known as "threshold criteria," in order to be selected. Criteria
3 through 7, called "balancing criteria," are evaluated to
determine which cleanup method provides the best overall
solution. . After considering public comments on the Proposed
Plan, EPA has concluded there is no reason to alter the selected
remedy in this interim ROD on the basis of the last two
"modifying" criteria.
1. Overall protection of human health and the environment
determines whether an alternative eliminates, reduces, or
controls threats to public health and the environment through
institutional controls, engineering controls, or treatment.
The alternatives that would be most protective of human
health and the environment are:
4b Geosynthetic Cover, Active Drainage
4c Composite Cover, Passive Drainage
5 Geosynthetic Cover, Seep Control
6 Geosynthetic Cover, Seep and Zone 2 Ground Water
Controls
All of these alternatives would protect human health and the
environment in the short and long term by effectively containing
the landfill wastes and minimizing the migration of contaminants
from the Site through the landfill berms or through the deeper
ground water zone. These alternatives meet all the remedial
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action objectives (RAOs) which are described in Section 7.0 of
this ROD.
Alternatives that are not protective of human health and the
environment are:
1 No Action
2 Active Seep Interception
2b Leachate Collection with Treatment Berm
2b(ii) Leachate Collection with Discharge to POTW
3 Seep and Zone 2 Ground Water Controls
4a Soil Cover, Passive Drainage
i
The No Action (1), Active Seep Interception (2), and Soil Cover
with Passive Drainage (4a) alternatives would not protect human
health and the environment because they allow the continued
migration of contaminants from the landfill. The No Action (1)
and Soil Cover (4a) alternatives would allow the continued
release of leachate into surface waters at levels exceeding
surface water ARARs, and would fail to attain other RAOs as well.
Alternatives 1 and 2 would allow the continued migration of
contaminated Zone 2 ground water, and would not prevent contact
with landfill contaminants. Alternative 3 would not meet the RAO
to minimize infiltration into the landfill waste, and it may not
meet the RAO to prevent direct contact with the landfill waste
and surface water contamination.
The Leachate Collection with Treatment Berm (2b) Alternative
and the Leachate Collection with Discharge to POTW [2b(ii)]
Alternative are not considered to be protective of human health
and the environment because EPA has significant concerns
regarding whether the unproven collection systems proposed for
these alternatives, and the unproven Treatment Berm approach
proposed for Alternative 2b, would work in the field. There is
considerable uncertainty regarding whether Alternative 2b and
2b(ii) would meet many of the RAOs.
There is uncertainty regarding whether the collection
systems proposed for the Treatment Berm (2b) or the Discharge to
POTW [2b(ii)J alternatives would meet the Zone 1 Leachate RAO,
which requires the elimination of leachate that exceed surface
water ARARs from, through, and/or under the source area berm.
The collection systems proposed for these two alternatives carry
significant risk of failure, including the potential for clogging
or plugging, and the potential for higher-than-predicted
operation and maintenance (O&M) costs due to such problems, and
therefore are not considered by EPA to be protective in the long
term. These alternatives, as currently configured, may not
effectively address exposure to chemical or biological
contamination that has been found in water on the landfill
surface. These alternatives may not meet the RAO to prevent
inhalation and release of landfill gas that exceeds ambient air
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standards,29 and over the long term would not meet the RAO to
minimize migration of contaminated ground water to the sloughs.
These alternatives would not meet the RAO to minimize
infiltration into the landfill.
The Treatment Berm system proposed for Alternative 2b is an
unproven technology for a Site like Tulalip Landfill, and EPA has
serious concerns that the proposed Treatment Berms would not be
effective in the long term, would not reduce risks posed by Site
contaminants, and would be relatively impermanent. The Treatment
Berms could clog relatively quickly, requiring costly frequent
replacement of the berms or a significantly higher level of O&M
to maintain flow. EPA is concerned that the unproven Treatment
Berms may not "treat" landfill contaminants at all, but merely
dilute contaminants with "clean" estuary waters before releasing
them to the surrounding environment. If the Treatment Berms were
to fail to treat contaminants, implementation of Alternative 2b
could worsen existing environmental problems at the landfill by
hastening the migration of landfill contaminants into the
surrounding estuary, and increasing contaminant loading from the
Site to the estuary.
Because Alternative 4b - Geosynthetic Cover with Active
Drainage, relies relatively heavily on an active system (i.e.,
pumps to remove surface water), it also is expected to be less
effective in the long term. If the pumping system breaks down or
fails to move water off of the cover system quickly, more surface
water will tend to penetrate any leaks the capping system. This
alternative is also considered to be relatively impermanent
because active, mechanical systems employing pumps require a
higher level of maintenance than passive systems, and are
vulnerable to potential increases i-n" the price of power to run
them.
2. Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs) evaluates whether the alternative meets
State and Federal—environmental laws, regulations, and other
requirements that pertain to the Site or, if not, whether a
waiver is justified.
Alternatives that are expected to meet all ARARs set out in
Section 11.2 of this interim ROD are:
29 Construction of either of these two alternatives could lead to
increased landfill gas generation. Gas generation in the landfill is
currently at a relatively low level probably because most of the waste is
saturated. The collection systems proposed for these alternatives, if they
work, would lower the height of the leachate mound in Zone 1, leaving much of
the waste unsaturated, and a significant increase in landfill gas generation
could result. Neither of these two alternatives provides for collection or
treatment of landfill gas.
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4c Geosynthetic Cover, Passive Drainage
4d Composite Cover, Passive Drainage
5 Geosynthetic Cover, Seep Control
6 Geosynthetic Cover, Seep and Zone 2 Ground Water
Controls
These alternatives are expected to achieve surface water ARARs at
the landfill berm (see Table 11-1) by eliminating leachate seeps,
and at the sloughs by eliminating or minimizing Zone 2 ground
water migration. These alternatives also meet Minimum Functional
Standards (MFS) requirements promulgated by the State of
Washington for closure of solid waste landfills. In the long
term, these alternatives are expected to contribute to the
achievement of state sediment management standards by ceasing the
surface discharge of leachate and minimizing the subsurface
discharges of leachate that contribute to contamination of off-
source sediments.
The following alternatives do not meet some of the ARARs
identified in Section 11.2 of this interim ROD:
1 No Action
2 Active Seep Interception
2b Leachate Collection with Discharge to Treatment Berm
2b(ii) Leachate Collection with Discharge to POTW
3 Leachate Seep and Ground Water Collection and
Treatment
4a Soil Cover, Passive Drainage
4b Geosynthetic Cover, Active Drainage
The No Action alternative (1) would not meet surface water ARARs
at the leachate seeps nor where Zone 2 ground water discharges to
the sloughs. Active Seep Interception (2) would not meet surface
water ARARs where Zone 2 ground water discharges to the sloughs.
The Soil Cover (4a) is not expected to meet surface water ARARs
at either the seeps nor the sloughs, and would not meet the MFS
requirements for closure of landfills.
*r~~
Alternatives 1, 2, 2b, 2b(ii), and 3 do not comply with MFS
because they do not include a landfill cover. Alternative 4b,
Geosynthetic Cover with Active Drainage, does not comply with MFS
because this alternative includes numerous drainage ditches that
are less than a 2% slope. Because these alternatives do not meet
the MFS ARAR, in order to select any of these alternatives, a
waiver of the MFS requirements would have to be invoked, pursuant
to 40 C.F.R. 300.430 (f) (1) (ii) (C) , or EPA would have to find that
these minimum specifications for closing landfills are either not
relevant or not appropriate at this Site.
In addition, the Leachate Collection with Treatment Berm
(2b) alternative may not meet surface water ARARs at the face of
the treatment berm if the berm is not effective, and it may not
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meet surface water ARARs at the sloughs if the collection system
is not effective. Finally, because Alternative 2b requires
dredging and filling of off-source wetlands, it may not meet
Section 404(b) of the Clean Water Act (CWA), which is an ARAR for
the Site. CWA 404(b)(1) requires avoidance of wetland
destruction if alternative actions are available. Because there
are -other containment alternatives which could meet the cleanup
objectives that have been identified, EPA may be unable to find
that there is no practicable alternative to the dredge and fill,
as required by Section 404(b) of the CWA.
The alternatives that EPA has determined meet the two
threshold criteria (Alternatives 4c, 4d, 5, and 6) will be
carried forward through this analysis and evaluated against the
balancing criteria. The alternatives that EPA has determined do
not meet both of the NCP threshold evaluation criteria
[Alternatives 1, 2, 2b, 2b(ii), 3, 4a, and 4b] will not be
carried further through this analysis for evaluation against the
other NCP criteria,30
3. Long-term effectiveness and permanence considers the ability
of an alternative to maintain protection of human health and the
environment over time, and the reliability of such protection.
Alternatives that are expected to be permanent and effective
in the long term are:
4c Geosynthetic Cover, Passive Drainage
4d Composite Cover, Passive Drainage
5 Geosynthetic Cover, Seep Control
6 Geosynthetic Cover, Seep and Zone 2 Ground Water
Controls
By effectively eliminating all leachate migration from the
Site through the landfill berm and eliminating or minimizing
leachate migration through the deeper Zone 2 ground water, and by
preventing contact with the landfill wastes, these alternatives
are expected to effectively contain the landfill wastes and
result in no significant residual risk from the source area.
These are technologies that have been implemented at hundreds of
sites across the country and are known to be relatively effective
in the long term. Alternatives 4c and 4d are relatively passive
systems (i.e. relatively little need for an outside power source
30 It is inappropriate to carry Alternatives 1, 2, 2b, 2b(ii), 3, 4a,
and 4b further through the NCP criteria evaluation because none of these
alternatives meet the threshold criteria. However, it should be noted that,
in general, these alternatives also compare poorly against the NCP balancing
criteria as well as the threshold criteria. A summary of how EPA would
evaluate Alternatives 2b, 2b(ii), 3, and 4b in relation to the balancing
criteria is provided in Appendix A of this interim ROD.
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or treatment plant), which increases their permanence and
decreases the costs of long-term operation and maintenance of the
remedy. Alternatives 5 and 6 are considered to be somewhat less
permanent than Alternatives 4c and 4d because they are not
passive systems.
4. . Reduction of toxicity, mobility, or volume through treatment
evaluates an alternatives's use of treatment to reduce the
harmful effects of principal contaminants, their ability to move
in the environment, and the amount of residual contamination
remaining.
Alternative 6 - Cover, Seep and Zone 2 Ground Water
Controls, is expected to effectively treat Site contaminants.
This alternative would collect and treat the leachate generated
by the Site and send it to an off-site sewage treatment plant, or
to a treatment plant that would be constructed on-site.
Alternatives 5 - Cover, Seep Control, would partially meet
this criterion because it would intercept and treat leachate
exiting the perimeter berm, but would not treat the deeper Zone 2
ground water.
Alternatives 4c - Geosynthetic Cover with Passive Drainage,
and 4d - Composite Cover with Passive Drainage, are consistent
with the presumptive remedy approach of containment of landfill
wastes and do not employ any form of treatment.
5. Short-term effectiveness considers how fast the alternative
reaches .the cleanup goal and the risks the alternative poses to
workers, residents, and the environment during construction or
implementation of the alternative.'
None of these alternatives is expected to pose risk to the
surrounding community during construction or implementation
because the Site is relatively isolated. Any significant impacts
would likely be confined to the immediate vicinity of the Site
and would be mitigated. - -
Each of Alternatives 4c, 4d, 5, and 6 would potentially pose
some risk to workers because all involve some excavation and
regrading of waste. However, the type_o_f excavation these
alternatives would require is relatively common, and it is
anticipated that effective measures would be taken to mitigate
any potential risk.
Alternatives 4c, 4d, 5, and 6 may have some short-term
adverse impact on the environment during implementation or
construction. These capping alternatives would require importing
fill material to bring the landfill surface up to the 2% minimum
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grades required by MFS.31 This additional weight on the
landfill may cause a short-term increase in leachate migration
through the seeps. .On the other hand, Alternatives 5 and 6,
which include seep controls, would not have this problem if the
seep controls were constructed prior to importing fill for
construction of the cover, because the leachate collection system
would collect any additional short-term leachate.
Each of Alternatives 4c, 4d, 5, and 6 would potentially
achieve the cleanup objective for eliminating the release of
leachate from surface seeps. The following alternatives are
predicted to "dry up" the leachate seeps and meet surface water
ARARs at the sloughs within 2 years of construction completion:
4c Geosynthetic Cover, Passive Drainage
4d Composite Cover, Passive Drainage
These alternatives would cut off infiltration of rain water
through the waste, thus minimizing the generation of new
leachate. As the existing leachate mound within the waste
dissipates, the perimeter seeps are expected to cease to flow
within two years, according to the results of ground water
modeling conducted by the Respondents during the RI/FS.
The following alternatives would be expected to meet the
cleanup goals for leachate seeps immediately after
implementation:
5 Geosynthetic Cover, Leachate Seep Control
6 Geosynthetic Cover, Seep and Zone 2 Ground Water
Controls
These alternatives would intercept and collect the perimeter berm
leachate, which would result in faster elimination of the seeps.
6. Implementability considers the technical and administrative
feasibility of implementing the alternative, such as the relative
availability of goods and services. Also, it considers if the
technology been used successfully on other similar sites.
Alternatives 4c, 4d, 5, and 6 include construction of a low-
permeability landfill cover. Technically, construction of a low
permeability landfill cover is a common landfill remedy that can
be readily implemented at Tulalip Landfill. Generally, materials
for these types of covers are available. The most significant
difference in implementability regarding the Tulalip Landfill, in
comparison with many other landfills, is that Tulalip landfill is
31 However, the amount of off-site fill that would need to be imported
can be reduced by re-positioning existing landfill materials to achieve the
necessary grades.
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relatively flat, so that a mounded cover must be constructed to
minimize infiltration and generation of leachate.
Another aspect of implementability is the ability to monitor
the remedy's effectiveness, and the ease of maintaining the
remedy. Based on EPA's experience at other CERCLA landfills
acrpss the country, geosynthetic covers have a known performance
record and are relatively reliable if properly constructed. It
would be relatively easy to monitor the perimeter leachate seeps
to evaluate if they dry up. Water levels in piezometers located
on the landfill could be monitored to evaluate whether the
leachate mound within the waste is falling, which would indicate
a reduction in leachate migration through the deeper Zone 2
ground water. An advantage of a landfill cover is that if an
obvious problem becomes apparent, such as surface water ponding
in the case of a passive drainage cover, it is relatively easy to
access and make repairs because the cover is close to the surface
of the landfill. All covers develop leaks, and installing a leak
detection system beneath the cover is not practical. Non-
essential perforations through the cover system should be
minimized as they can contribute to imperfections in sealing the
liner and in increased leakage.
Alternative 4c - Geosynthetic Cover with Passive Drainage,
is clearly implementable at the Site. Alternative 5,
Geosynthetic Cover with Seep Control, is considered somewhat less
implementable because it relies on the long-term availability of
capacity at a sewage treatment plant to accept and treat the
collected leachate, which could be a potential administrative
problem. The cost of building an on-site treatment plant would
significantly increase the cost of this alternative.
Alternative 4d - Composite Cover, Passive Drainage, and
Alternative 6 - Geosynthetic Cover, Seep and Zone 2 Ground Water
Controls, are considered significantly less implementable.
Materials to construct these alternatives are expected to be
readily available. However, the Composite Cover with Passive
Drainage (4d) would be technically difficult to construct because
it would be time consuming and expensive to ensure that all soil
material used in a soil barrier layer would meet the required
standard for impermeability. An extensive construction
monitoring program would be required. The technical
implementability of the Cover with Seep Controls and Ground Water
Controls alternative (6) is considered relatively infeasible
because of the difficulty in constructing a slurry wall down into
the Zone 2 aquifer. Problems such as heaving sands could make
construction of such a slurry wall difficult. Also, there is no
clear aquitard at depth into which a Zone 2 slurry wall could be
effectively anchored. Without an aquitard to anchor the slurry
wall, the ground water extraction system could potentially pull
in significant volumes of "clean" water from the sloughs along
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with contaminated ground water, which may greatly increase the
treatment costs for this alternative.
7. Cost includes estimated capital and operation and
maintenance (O&M) costs, as well as present worth costs. Present
worth cost is the total cost of an alternative over time in terms
of today's dollars. Cost comparison information.for all of the
alternatives evaluated (including those which do not meet the NCP
threshold criteria) is provided in Table 9-1. The net present
value of each alternative is listed in millions of dollars,
calculated using a discount rate of 5% over 30 years.32
8. State acceptance: Because the Tulalip Landfill is located
entirely on the Tulalip Indian Reservation, this criterion for
this Site is more appropriately "Tribal Acceptance." Based on
comments received from the Tulalip Tribes during the public
comment period on the Proposed Plan, it is clear that the Tulalip
Tribes support the selected alternative. Although State
concurrence is not necessary for this Site because the landfill
is located on an Indian Reservation, EPA notes that the State of
Washington concurs with the selected alternative.33
9. Community acceptance considers public response to EPA's
Proposed Plan during the public comment period. EPA provided an
80-day public comment period on the interim cleanup options for
the Site, and held two public meetings during the comment
period.34 Comments were received on a wide variety of complex
issues such as the remedy selection process, data collected from
the Site, the Streamlined Risk Assessment, the relative cost of
various remedies, concerns about fairness, and concerns about the
Site's potential impact on the environment and human health. A
summary of significant comments received during the public
comment period, and EPA's responses to these comments, is
provided in the "Responsiveness Summary" attached to this Record
of Decision (ROD).
Based on EPA's evaluation of the comments received, almost
all commentors expressed support or opposition to Alternative 4c,
EPA's preferred alternative in the Proposed Plan. The following
parties expressed general opposition to the preferred
alternative:
32
EPA notes that the need for continued O&M could exceed 30 years.
33 See February 22, 1996, letter from Mary E. Burg of State of
Washington Department of Ecology to Chuck Clarke of EPA, in the Administrative
Record for this interim remedial action.
34 The NCP requires a minimum public comment period of only 30 days.
EPA extended the 30-day public comment period for the Tulalip Landfill
Proposed Plan to 80 days.
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• Some of the Potentially Responsible Parties (PRPs), their
attorneys, and consultants
• Balance Council, an organization which represents some of
the PRPs
The following parties expressed general support for the preferred
alternative:
Citizens who live near the Site
People for Puget Sound
Audubon Society
Tulalip Tribes of Washington, and their consultants
Northwest Indian Fisheries Commission
The Northwest Indian Fisheries Commission expressed support for
the preferred alternative but argued it didn't go far enough and
more should be done. The Snohomish County Health District
provided comments but did not take a clear position with regard
to the preferred alternative.
Based on the comments received, EPA believes the selected
remedy will be acceptable to citizens who live near the Site and
who may use the areas around the Site.
Compatibility with Anticipated Future Land Use is an
additional element of Community Acceptance, which, in the case of
Tulalip Landfill, considers whether an alternative would be
compatible with commercial, light industrial, and recreational
use. Alternatives 4c, 4d, 5, and 6, which include a landfill
cover, are fully compatible with these future land use
objectives.
10.0 THE SELECTED INTERIM REMEDY
EPA has considered, at some point in the CERCLA process, all
of the alternatives that have ever been submitted to EPA by the
Respondents, including Alternative 2b and 2b(ii), which were
submitted after the Source Area Containment Feasibility Study was
approved by EPA. After the close of the public comment period,
EPA re-considered and re-evaluated all of the alternatives,
including those alternatives which do not include a landfill
cover. Based upon consideration of the requirements of CERCLA,
the detailed analysis of the alternatives using the nine NCP
criteria, and public comments, EPA has determined that
Alternative 4c, Geosynthetic Cover with Passive Drainage, is the
most appropriate interim remedial action for the Tulalip Landfill
Superfund Site. The Tulalip Tribes of Washington support this
determination. This interim remedy would achieve substantial
reduction in risk to the environment by containing the
contaminants within the landfill.
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EPA expects that a containment remedy that eliminates or
minimizes the total contaminant loading contribution from the
landfill would improve the long-term viability of the sensitive
surrounding environment. Of all of the alternatives considered
by EPA, a geosynthetic cover with passive drainage is the least
expensive, protective containment alternative that meets all
ARARs identified for this interim remedial action and that will,
with a relatively high degree of certainty, effectively stem the
generation and flow of contaminated leachate into the surface
waters surrounding the landfill. Because this containment remedy
relies on a "passive" design that does not include pumps to move
surface water off of the landfill surface, the selected remedy
would require less frequent monitoring to ensure that all the
pumps are operational. A low permeability cover is implementable
as a well known technology, and is expected to be effective in
the long-term.35 The selected interim remedy is a proven
technology, with established means to monitor and maintain the
cover. The selected interim remedy will reliably achieve the
remedial action objectives of reducing risks, without the need
for also establishing' elaborate contingency measures to plan for
the possible failure of less certain measures. This cover will
also allow for future use of the Site for recreation, light
industry or commercial enterprises, with certain institutional
controls required to protect the integrity of the cover.
Therefore, EPA believes that Alternative 4c provides the best
balance of trade-offs among the alternatives with respect to the
evaluation criteria.
EPA expects the selected interim remedy to be effective in
minimizing the migration of contaminated landfill leachate from
the source area. At present, the RI/FS shows that contaminated
leachate from the landfill wastes is migrating to surface water
by way of leachate seeps on the surface and through deeper ground
water that flows into the sloughs adjacent to the landfill.
Available information suggests that leachate migration is causing
contamination of soils, sediments, and fish in the off-source
wetlands. In the FS, the Respondents predict that a low
permeability cover will minimize the generation of additional
leachate by greatly reducing the movement of contaminated ground
water to surface water. This is expected to significantly reduce
mass loadings of metals, organics, and bioaccumulative substances
into the off-source sloughs and wetlands. By minimizing the
discharge of leachate from the landfill, the selected interim
remedy is also expected to minimize the discharge of resistant
strains of pathogenic microbes which have been found in landfill
leachate. For these reasons, the selected interim remedy in this
35 All covers develop leaks. However, leaks can be minimized through
proper design, construction materials, construction quality assurance
procedures, and O&M.
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ROD also includes EPA's decision to take no action to remediate
ground water.
10.1 DESCRIPTION OF THE SELECTED REMEDY
The selected interim remedy requires installation of an
engineered, low permeability cover over the source area of the
landfill. The source area to be covered shall include the waste
that is located within the current perimeter of the approximately
147 acre landfill, including any waste or contaminated soils in
the perimeter berm, and any contaminated soils in the existing
cover material. The interim remedy shall include the following:
10.1.1 General Interim Remedy Requirements
The interim remedy shall be designed and constructed in
accordance with the Remedial Action Objectives (RAOs) described
in Section 7 of this ROD. The work will be conducted in
accordance with plans approved by EPA. Guidance documents
including, but not limited to, the guidance documents listed in
the Appendix C of this interim ROD, shall be used to design,
construct, and operate and maintain the landfill cover system.
During detailed design, potential problems that may occur during
implementation of the selected remedial action, such as the
effect of surface water discharge on off-source wetlands, will be
evaluated and addressed as appropriate. In general, all
components of the interim remedy (e.g., gas collection pipes)
shall be constructed beneath the surface of the cover system to
facilitate future use objectives that have been identified for
the Site. Non-essential perforations through the cover system
shall be minimized.
This interim remedial action is expected to result in
adverse impacts or loss of approximately 1.7 acres of off-source
wetlands. All such losses or impacts to off-source wetlands
shall be properly addressed under the substantive requirements of
Section 404 of the CWA. During all phases of the interim
remedial action, any adverse impacts and potential adverse
impacts to the off-source area shall be avoided and minimized.
Any adverse impacts shall be mitigated. As part of complying
with the Stormwater Runoff and Erosion Surface RAO, surface water
runoff from the cover system shall be released to the surrounding
environment at a controlled rate and in a controlled manner such
that damage to the surrounding environment is prevented. The
interim action shall avoid and minimize adverse impact to the
aesthetic value of the off-source wetlands. The interim action
shall not result in erosion of off-source wetlands or destabilize
wetland banks.
Mitigation or replacement for the loss of any on-source
wetlands that have grown on the landfill surface since the
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existing cover material was placed over the waste in 1979 will
not be required under CWA Section 402.36
10.1.2 Regrading
The cover system shall be designed and constructed so that
the grade of the surface slopes shall be no less than two percent
after allowing for predicted settlement. The final grades shall
be attained through importing "clean fill" to the Site, and
through excavation or regrading of waste and existing cover'soil.
Imported clean fill may be temporarily stockpiled on the source
area prior to regrading activities, however, erosion control
measures must be implemented to prevent erosion of the stockpiled
fill into the surrounding wetlands.
A Regrading Erosion Control Plan shall be developed and
approved by EPA prior to initiation of regrading activities.
This Plan shall ensure that regrading activities do not result in
erosion of on-source soil to off-source areas. The Plan shall
incorporate appropriate erosion control measures which may
include, but are not limited to, silt fences and sedimentation
ponds.
Appropriate measures shall be implemented to ensure control
of dust during regrading activities.
Appropriate measures shall be implemented to ensure that
odors are minimized during regrading activities. Regrading
activities shall be planned and implemented such that the amount
of time that waste is exposed to air shall be minimized. Any and
all exposed waste shall be thoroughly covered with at least six
inches of "clean" cover soil at the end of each construction day.
10.1.3 Landfill Cover System
The landfill cover system shall consist, from the lowest
layer to the uppermost layer,, of the following:
Gas collection system: A landfill gas collection system
located between the waste and the cushion layer shall be
designed, constructed, operated, and maintained to control
combustible or toxic gas release from the landfill waste.
Collection pipes shall be installed below the surface of the
cover system. The gas collection system, and any associated
features such as vents, shall be designed and constructed to
be flush with the surface of the landfill so as not to
36 For more information, see the subheading "Operations at the Landfill
after 1985" in Section 2.0 - Site History and Enforcement Actions of this
interim ROD; see also interim ROD Section 11.2.3 - Action-Specific ARARs.
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interfere with future land use activities on the landfill
surface. The gas collection system shall be designed to be
compatible with a landfill gas treatment system, which may
need to be added after construction of the gas collection
system is completed. The gas collection system shall be
designed and constructed .so that if the addition of a gas
treatment system becomes necessary, the collection system
can be modified to incorporate the gas treatment system
without constructing additional gas collection pipes above
the landfill surface.
Cushion layer: A cushion layer shall be placed over the
landfill waste to minimize the potential of the waste
damaging the low hydraulic conductivity layer. The cushion
layer shall have a minimum thickness of 1 foot (12 inches),
and shall be free of rock, fractured stone, debris, cobbles,
rubbish and roots. In general, the cushion layer shall be
designed and constructed in accordance with the following
requirements:
•'" One hundred percent (100%) of the largest soil
particles in the cushion layer shall pass the .75"
sieve.
• The top 6 (six) inches of the cushion layer shall be
no coarser than Unified Soil Classification System
(USCS) sand (SP) with 100% of the washed, rounded sand
passing the .25" sieve.
• The cushion layer shall be uniformly compacted to a
minimum 90% modified proctor density (ASTM D1557) and
shall be smoothed with a smooth drum or vibratory
roller.
• Deformations in the cushion layer surface shall not be
greater than 1 inch in depth, except if the bedding
.surface is frozen. If the bedding surface is frozen,
then deformations shall be no greater than .5 inches in
depth.
Low hydraulic conductivity layer: A low hydraulic
conductivity layer shall consist of either of the following:
• a minimum 50 mils flexible membrane liner designed, .
constructed, operated and maintained to minimize
infiltration of water into the landfill; or
• a geosynthetic clay liner with a maximum permeability
of 1 X 10~9 cm/sec designed, constructed, operated and
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maintained to minimize infiltration of water into the
landfill.37
Cover layer: A cover layer shall be compromised of a
minimum of 1 foot (12 inches) of soil capable of sustaining
plant species that will minimize erosion and providing
adequate depth and composition to minimize damage to the low
' hydraulic conductivity layer (i.e., loading and stresses
from above, plant species roots and burrowing animal
intrusion, etc.)
Vegetation layer: The uppermost component is vegetation
designed to impede erosion while still allowing surface
runoff from major storm events. Seed for the vegetation
layer shall be sown as soon as practicable after placement
of the cover layer to minimize erosion of the cover layer.
If the vegetative layer does not "take" in. all portions of
the cover, these areas shall be reseeded as necessary until
the vegetative layer is sufficiently established. Plant
species that may invade or otherwise impair the off-source
wetlands shall not be selected for the vegetation layer.
The cover system shall incorporate the construction of, at a
minimum,. 5 piezometers that shall be located and installed for
the purpose of evaluating the height of the Zone 1 leachate mound
after construction of the interim remedy.
The cover surface slopes shall not be less than two percent,
after accommodating for settlement and subsidence, and the side
slopes shall not be more than thirty-three percent.
The cover system shall be designed, operated, constructed
and maintained to the meet the following performance standards:
(a) Prevent direct contact of people, animals, and surface
water with landfill waste.
' ***
(b) Prevent landfill waste from being wind blown.
(c) Provide long-term minimization of migration of liquids
through the landfill.
(d) Function with minimum maintenance.
(e) Promote drainage and minimize erosion or abrasion of
the cover.
37 A geosynthetic clay liner is reasonably expected to achieve a
maximum permeability of 1 X 10'9 cm/sec. The Respondents assumed this
permeability rate in the ground water modeling they conducted for this
remedial alternative during the RI.
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•
(f) Prevent damage to the cover from a 100-year flood
event.
(g) Accommodate settling and subsidence so that the cover's
integrity is maintained.
(h) Ensure that the perimeter berm or edge of the landfill
is structurally stable.
(i) Establish and implement a construction quality
assurance (CQA) program for the cover system to ensure
that the constructed cover meets or exceeds all design
criteria and specifications. This shall include, but
shall not be limited to, aggressive testing of field
seams to ensure water tightness, and field placement
oversight.
The cover system design shall include permanent access roads
for operation and maintenance (O&M) activities.
10.1.4 Air Controls
If necessary to meet PSAPCA requirements, a landfill gas
treatment system shall be installed. Additional study shall be
conducted during remedial design to evaluate whether a landfill
gas treatment system is needed. However, it is possible that
sufficient information on which to base a decision on whether gas
treatment is necessary may be available only after construction
of the interim remedy.
10.1.5 Post-Construction Care
'•»
The integrity and effectiveness of the final cover shall be
maintained, including periodic inspections and making repairs to
the cover as necessary to correct the effects of settling,
subsidence, erosion, or other events. A written Operation and
Maintenance (O&M) Plan shall be completed and approved by EPA.
The O&M Plan shall be fully implemented at the Site in
perpetuity, or until EPA determines in writing that
implementation of the O&M Plan is no longer necessary at the
Site.
Post-construction escape of leachate or contaminated run-off
shall be controlled, minimized or eliminated, to the extent
necessary, to protect human health and the environment. Run-on
and run-off shall be prevented from eroding or otherwise damaging
the final cover and the surrounding wetlands and tributaries
including the tidal channels.
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Post-Construction Monitoring
A post-construction monitoring plan shall be prepared. The
plan shall be approved by EPA. The monitoring plan shall be
sufficient to provide for evaluation of the effectiveness of the
remedy and evaluate whether the remedy remains protective of
human health and the environment. Post-construction monitoring
of the interim remedy shall consist of, at a minimum, the
following:
• Perimeter leachate seeps: A minimum of 10 landfill
perimeter leachate seeps shall be located and identified for
sampling. On a quarterly basis, the leachate seeps shall be
sampled and analyzed for chemicals that are surface water
ARARs (during detailed design, EPA may select a subset of
the surface water ARARs from Table 11-1 to be used for post-
construction monitoring purposes). For metals, total metals
analyses shall be performed for the pe.rimeter leachate seep
samples. The validated data results shall be provided to
EPA, on paper in raw and summary form, and electronically
(i.e., a computer file) in a format acceptable to EPA.
Data validation reports for all of the samples shall be
included. The flow rate from each seep shall be measured,
and the daily flow rate from all ten seeps shall be
estimated. All of this information described in this
paragraph, including the validated sample results, shall be
reported to EPA within 3 months of each sampling event as
part of a "quarterly monitoring report". The "quarterly
monitoring report" shall include a summary narrative that
includes information relevant to the sampling "event and data
analyses, such as the date(s) the samples were taken, who
took the samples, and any problems that were encountered.
Each "quarterly monitoring report" shall provide one graph
for each leachate seep which compares the flow estimate of
each leachate seep from the most recent sampling round with
each of the flow estimates from the seep from all previous
sampling rounds.
• Zone 1 Piezometers: the Zone 1 leachate mound levels in the
on-source piezometers shall be measured on a quarterly
basis, and this information shall be submitted to EPA in the
next quarterly monitoring report. Each quarterly monitoring
report shall provide a graph or graphs which compares each
piezometer water level reading from the most recent sampling
rounds with that piezometer's water level readings from all
previous sampling rounds.
• Zone 2 ground water: Because the selected remedy is
expected to effectively contain the landfill wastes by
minimizing the migration of leachate away from the landfill,
and because, based on current information, EPA does not
expect that additional, future actions will be necessary to
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remediate Zone 2 ground water, EPA concludes that post-
construction data collection from of the Zone 2 aquifer is
unnecessary.
Landfill gas collection system: Monitoring requirements for
the landfill gas collection system shall be described in the
O&M Plan. These monitoring requirements shall be sufficient
to determine whether the a gas treatment system must be
added to ensure compliance with PSAPCA requirements. If a
landfill gas treatment system is added in the future, the
O&M Plan shall be amended to include monitoring requirements
for the gas treatment system.
EPA may require additional monitoring to assess or ensure the
short-term and long-term effectiveness and protectiveness of the
selected interim remedy. Each quarterly monitoring report shall
summarize all of the monitoring data collected during the
quarter, and shall provide, based on consideration of all of the
collected data, an evaluation of the effectiveness and
protectiveness of the interim remedy. Any changes or trends in
the data from previous quarter (s) shall be noted and described.
After the first two years of post -construct ion monitoring are
complete, EPA may re-evaluate the frequency of collection of the
post -monitoring data and the frequency of the quarterly
monitoring reports.
The point of compliance for contaminated ground water and
leachate is the location where ground water discharges to surface
water. For Zone 1 ground water (i.e., the leachate seeps), the
point of compliance shall be the location at which leachate exits
the exterior face of the perimeter landfill berm. For Zone 2
ground water, the point of compliance shall be the location where
Zone 2 ground water discharges to surface water. No mixing
zone(s) shall be allowed in surface water to 'measure compliance
with surface water ARARs . Because current information indicates
that the interim remedial action, if properly constructed, will
achieve the surface water ARARs where Zone 2 ground water
discharges to the sloughs, additional monitoring or evaluation of
the Zone 2 pathway for compliance purposes is unnecessary.
10.1.6 Institutional Controls
Institutional controls will be used to assure continued
effectiveness of the interim remedial action and to prevent human
exposure to contamination remaining at the Site at concentrations
above health-based risk levels. Specific controls include land
use restrictions to limit or prohibit activities that could
interfere with performance of the selected remedy. In addition,
ground water use restrictions will be implemented to prevent the
use of contaminated ground water.
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When design and construction of the interim remedy are
complete, EPA and the Tulalip Tribes shall develop and approve a
document titled "Routine Use of Tulalip ('Big Flats') Landfill,"
the purpose of which shall be to identify future uses of the Site
that are compatible with the continued integrity of the cover
system and protective of the off-source areas of the Site. This
document shall delineate routine site uses that may occur on the
surface of the cover and uses that shall not occur, in accordance
with the land use restrictions established in this interim ROD.
This document shall be implemented at the Site in perpetuity, or
until EPA and the Tulalip Tribes determine in writing that
implementation of the document is no longer necessary at the
Site. After the document is approved by EPA and the Tulalip
Tribes, the document can be modified by mutual written agreement
by both EPA and the Tulalip Tribes.
The land use and ground water use restrictions will be
imposed on all property that comprises the Site as covenants
running with the land for the purpose of protecting human health
and the environment by protecting in perpetuity the remedial
actions which have been and will be taken at the Site. One or
more instruments, including the "Routine Use of Tulalip ('Big
Flats') Landfill" document, in a form acceptable to EPA, shall be
prepared setting forth covenants, conditions and restrictions
that accomplish the following objectives:
• Existing "access roadways," including the east access
roadway, and the access roadways at the southeast and
northwest corners of the landfill surface running from the
landfill surface to the slough waterways, shall be preserved
as points of access to the landfill.
• An "Environmental Buffer Zone" on the surface of the
landfill cover shall be defined, established, and maintained
in perpetuity. The Environmental Buffer Zone shall extend
along the entire perimeter of the landfill, from the edge of
the landfill cover surface (not including the relatively
steep slope of the exterior face of any perimeter berm)
inward toward the center of the landfill. On the north,
east, and southern edges of the cover, the Environmental
Buffer Zone shall be no less than 50 feet in width. On the
entire western edge of the cover (i.e., the edge facing the
large, approximately 170-acre wetland area to the west of
the landfill), the Environmental Buffer Zone shall be no
less than 250 feet in width. The Environmental Buffer Zone
shall be preserved and maintained in perpetuity for passive
recreation activities such as walking. The Environmental
Buffer Zone shall be seeded with vegetation that is
compatible with the landfill cover system and that will also
provide beneficial habitat uses for wildlife. No
structures, materials, or other objects shall be located,
placed, stored, or constructed on the Environmental Buffer
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Zone, with the following sole exception: the Environmental
Buffer Zone may be crossed by necessary Site access
roadways. These access roadways shall be constructed and
maintained in a manner that is consistent with and does not
inhibit the recreational use of the Environmental Buffer
Zone. v
• A clearly visible sign shall be placed and maintained in
perpetuity at the landfill entrance which summarizes the
activities that may occur on the landfill cover, and shall
also summarize the restrictions on use, as described in the
"Routine Use of Tulalip ('Big Flats') Landfill" document.
The sign shall also depict a map of the Site which clearly
delineates the locations and extent of the Environmental
Buffer Zone, and shall clearly summarize the use
restrictions for the Site, including a written description
of the Environmental Buffer Zone and their purpose. The
sign shall include the phone number of a Tribal officer or
employee who is familiar with the requirements of the
"Routine Use of Tulalip ('Big Flats') Landfill" document and
is able to provide direction to potential users of the Site
regarding the requirements of the document.
• Site users shall comply with the "Routine Use of Tulalip
('Big Flats') Landfill" document described above.
Any commercial or development activity on the landfill
surface will require advance, written agreement between EPA and
the Tribes to ensure the continued integrity of the cover system
and to ensure protection of human health and the environment.
10.2 INTEGRATING THE INTERIM ACTION WITH LAND USE PLANS
The selected interim remedy shall allow the on-source area
of the Site to be productively used by people, with some
restrictions necessary to prevent damage to the interim remedy.
The selected interim Remedy shall be designed and constructed to
allow for the types of future use activities described in the Big
Flats Land Use Program, Tulalip Landfill Remedial Investigation
and Feasibility Study (July 10, 1994) .
10.3 PERIODIC REVIEW
Because the interim remedial action will result in hazardous
substances remaining on-site above health-based levels, a 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. If the five-year review indicates that this interim
remedial action is not providing adequate protection of human
health and the environment, additional containment action for the
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source area, such as Implementation of a perimeter leachate
collection and treatment system, may be necessary.
10.4 ESTIMATED COST OF THE SELECTED INTERIM REMEDY
EPA's total cost estimate for the selected interim remedy is
$25.1 million.38 This cost estimate reflects the total cost
estimate provided by the Respondents in the Source Area
Containment Feasibility Study ($22.4 million), in addition to an
EPA cost estimate that accounts for the possibility that a
landfill gas treatment system may be necessary ($2.7 million).
As summarized in Table 10-1, the Respondents' cost estimate
for the selected interim remedy has capital costs of $19.8
million and annual operation and maintenance costs of $170,000
per year. The total net present value of their estimate is
approximately $22.4 million, assuming a net discount rate of 5%.
Costs for this alternative are highly dependent on the assumption
that the perimeter elevation of the graded surface will be 12
feet; raising or lowering this elevation could have a significant
impact on the cost because it may directly affect the amount of
off-Site fill that would need to be brought in to achieve the 2%
surface grades required by the State of Washington MFS. Table
10-1 shows that the cost estimate for "import soil" for grading
purposes is $4,000,000, out of total capital costs of
$19,841,000.
Figure 10-1 shows EPA's probable cost estimate for a
contingent landfill gas treatment system, which may be necessary
to comply with air pollution control requirements. The total net
present value for the contingent gas system, assuming a net
discount rate of 5%, is $2.7 million. O&M costs for the gas
treatment options range from $75,000 per year for a surface
collection system with an open flare, to $131,000 per year for a
vertical well system with an enclosed flare. Information
supporting this probable cost estimate is provided in Figure 10-1
and Appendix B of this interim ROD.
11.0 STATUTORY DETERMINATIONS
The interim remedial action selected for implementation at
the Tulalip Landfill Site is protective of human health and the
environment, complies with Federal and State applicable or
relevant and appropriate requirements for this limited-scope
action, and is cost-effective. Because this action may not
38 Remedy alternative cost estimates assume Operation and Maintenance
(O&M) costs over a 30-year period and a discount rate of 5%. The actual
number of years that O&M may be required at the Site may be greater than 30
years. Actual Site costs are predicted to fall within a range of +50 per cent
to -30 per cent for all remedy alternative cost estimates.
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constitute the final remedy for the Site, the statutory
preference for remedies that employ treatment that reduces
toxicity, mobility,•or volume as a principal element, may be
further addressed by a final response action. Given that this is
an interim action ROD, review of this Site and of this interim
remedy will be ongoing as EPA continues to evaluate whether
additional remedies for the on-source or off-source area of the
Site are necessary.
11.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The selected interim remedy is protective of human health
and the environment. The interim remedy at this Site 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 to restrict
disturbance of the cover. The seep contact, seep migration, and
groundwater migration RAOs are achieved by minimizing
infiltration thereby minimizing leachate generation. As a
result, the interim remedial action will be protective of human
health and the environment in the long term.
The interim remedial action includes significant
construction activities that could pose minor risks to workers
and will result in the loss of approximately 1.7 acres of off-
source wetlands. These risks and off-source wetlands loss will
be mitigated as appropriate to ensure that this alternative is
protective of human health and the environment.
11.2 COMPLIANCE WITH ARARS
This interim action complies with Federal and State
applicable or relevant and appropriate requirements (ARARs) for
this limited-scope action. As stated above, this interim action
will minimize infiltration and leachate generation. Thus, seeps
and ground water discharge with constituent concentrations that
exceed chemical specific ARARs will be eliminated or minimized.
The Site is located on Tribal lands, and leachate from the
Site is discharged to surrounding wetlands, tidal channels, and
sloughs. State environmental laws and regulations affecting
actions taken or occurring entirely on-Site are not legally
applicable, but nevertheless may be relevant and appropriate.
Under Section 300.400(g)(2) of the NCP, certain state laws and
regulations may be relevant and appropriate to this interim
remedial action. For example, the state laws and regulations may
be relevant and appropriate if the purpose of the state law or
regulation is similar to the purpose of this interim remedial
action (e.g., if there is a state regulation which sets surface
water quality standards for certain chemicals or substances for
the purpose of protection of aquatic life and human health, then
those regulations would be relevant and appropriate to this
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interim action, as the purpose of this interim action is to
protect aquatic life and human health from exposures to hazardous
substances contained in the landfill leachate). As a general
matter, permits are not required for on-site actions at NPL
Sites, however, the substantive requirements of a permit that
would otherwise be required must be met. The following is a
discussion of the ARARs identified for this Site and for the
selected interim remedial action.
11.2.1 Chemical-Specific ARARs
Chemical-specific requirements are usually health- or risk-
based numerical values or methodologies that establish the
acceptable amount or concentration of a chemical in the ambient
environment. Following are the chemical-specific requirements
for the Tula-lip-Landfill:
State of Washington Water Pollution Control Act/Water
Resources Act -- Chapters 90.48 and 90.54 of the
Revised Code of Washington ("RCW").- and the State of
WashingtonWater Quality Standards for Surface Waters -
- Chapter 173-201A WAG
These statutes, through their implementing regulations
including, but not limited to, those requirements codified at
Chapter 173-201A of the Washington Administrative Code ("WAC"),
require the use of all known available and reasonable
technologies in the treatment of wastewater prior to a release or
discharge of such wastewater into waters of the State. The
statutes themselves do not contain any numerical criteria or
standards. However, Chapter 173-201A of the WAC contains both
narrative and quantitative limitations for protection of surface
waters by regulating discharges to sewers and surface waters, and
establish discharge limits for water quality parameters and toxic
substances.
Because the leachate seeps and Zone 2 groundwater at the
Site discharge into waters of the State, and since the WAC
Chapter 173-201A requirements set the water quality standards for
surface water, the WAC 173-201A regulations are relevant and
appropriate for this interim remedial action. Specifically, for
this interim remedial action, the surface water limitations 'are
described in Table 11-1. For monitoring purposes, EPA may select
a subset of the surface water ARARs listed in Table 11-1 during
detailed design. The surface water ARARs listed in Table 11-1 do
not account for practical quantitation limits (PQLs), or surface
water background. To account for PQLs and background, EPA plans
to adjust compliance levels for the Table 11-1 ARARs as
appropriate.
Given the presence of marine and estuarine aquatic organisms
in the waters surrounding the Landfill, the marine criteria
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listed in WAC 173-201A-040 are considered to be the relevant and
appropriate standards which are to be complied with for
discharges to surface waters associated with this interim action.
This interim action will attain the WAC 173-201A ARARs by
stemming the flow of contaminated ground from the source area.
Spegifically, the selected interim remedy is expected to minimize
the discharge of leachate to Zone 2, and eliminate the perimeter
berm leachate seep discharges through the perimeter berm. EPA
notes that the selected interim remedy is not expected to achieve
surface water ARARs immediately after construction. It may take
a few years (ground water modeling conducted by the Respondents
estimated 2 years) for the selected interim remedy to eliminate
the perimeter berm seeps, however, EPA expects that all surface
water ARARs will be met by the conclusion of remedial action at
the Site as required by CERCLA as amended by SARA. Over the long
term, Alterative 4c allows significantly less loading of
contaminants to the surrounding environment, and significantly
less leachate to discharge from the landfill than other, less
expensive alternatives, notably Alternatives 2b and 2b(ii).
Federal Water Pollution Control Act ("FWPCA")/Clean
Water Act ("CWA") -- 33 U.S.C. §§ 1251-1376; 40 C.F.R
Parts 100-149
These statutes and their implementing regulations govern
discharges of water and wastewater to sewers, surface water, and
site runoff that is directed to a water body subject to the Acts.
They establish point source standards for discharges into surface
water bodies under the National Pollutant Discharge Elimination
System ("NPDES"). They also establish ambient water quality
criteria ("AWQC") for the protection of aquatic organisms and
human health.
Federal AWQC, promulgated at 40 C.F.R. Part 131, are
guidelines set for various contaminants.in surface water bodies.
These guidelines are expected to be protective of most aquatic
life against acute or chronic toxicity, or protective of human
health with respect to fish consumption and water ingestion.
CERCLA Section 121(d)(2)(B)(i) specifically states that water
quality criteria are to be attained "where relevant and
appropriate" at CERCLA sites.
The federal AWQC are used by the States to set water quality
standards for surface water. See Chapter 173-201A WAC. In
general, the state water quality standards for surface water
adopt the federal AWQC, and in some cases are more stringent. In
those cases in which the state standards are more stringent than
the federal standards/ the state standards are more relevant and
appropriate than the federal standards.
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The federal AWQC are relevant and appropriate to this
interim action because the purpose of the federal AWQC, among
other things, is to-protect aquatic organisms and human health
from high levels of toxic pollutants, and the purpose of this
interim action is to minimize the release of leachate containing
toxic pollutants from the landfill to the adjacent wetlands and
sloughs which would harm human health and aquatic organisms.
Thus, EPA believes that the use of federal AWQC are well suited
to the Tulalip Landfill. Federal AWQC that are relevant and
appropriate requirements for this interim response are provided
in Table 11-1.
The wetlands and tidal channels surrounding the Site are
included in the CWA definition of "surface water," and the use of
AWQC to evaluate leachate seeps discharging directly into the
wetlands and tidal channels is therefore relevant and
appropriate.
This interim action is expected to attain surface water .
ARARs, including the federal AWQC, by stemming the flow of
contaminants from the landfill (see the last paragraph of the
section above regarding "State of Washington Water Pollution
Control Act/Water Resources Act").
Certain arguments were raised by the Respondents regarding
the federal AWQC and the state water quality standards during the
preparation of the Feasibility Study by the Respondents under the
AOC. The Respondents initiated the formal Dispute Resolution
process under the AOC to resolve these arguments. Since these
issues affected EPA's decision-making process at this Site, a
discussion of these disputed issues and the outcomes is given
below.
Use of Mixing Zones. EPA's final determination in the
Dispute Resolution process stated that mixing zones are not
appropriate- for evaluating" compliance with state water quality
standards at the Tulalip Landfill. EPA's position is consistent
with WAG Chapter 173-201A, which is identified as an ARAR in this
interim ROD for the Site. Under the CWA and WAC 173-201A-100,
the term "surface waters" includes wetlands, tidal channels, and
mudflats, which are precisely the kind of landforms found around
the perimeter of the landfill. Results of the RI indicate that
the landfill leachate contains hazardous substances in
concentrations exceeding the WAC 173-201A standards. This
leachate is regularly discharging directly to the wetlands and
mudflats that surround the landfill. Therefore, the leachate
discharges must attain the WAC 173-201A standards at the point
where leachate discharges into surface waters around the
landfill.
Respondents failed to justify the use of a mixing zone for
evaluating compliance with AWQCs because they did not provide to
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EPA in the RI/FS any information which shows that the Tulalip
Landfill leachate meets any of the conditions set forth in WAC
173-201A-100, which must be met in order for a mixing zone to be
granted. Some of these conditions include, but are not limited
to, information which clearly indicates the mixing zone would not
have a reasonable potential to cause a loss of sensitive or
important habitat, substantially interfere with the existing or
characteristic uses of the water body, result in damage to the
ecosystem, or adversely affect public health. See WAC 173-201A-
100(4) . Information collected by the Respondents' contractors
shows numerous measured exceedances of AWQC in landfill leachate.
These exceedances indicate that the landfill leachate has a
reasonable potential to present an imminent and substantial
endangerment to public health, welfare, or the environment.
Additionally, EPA believes that use of a mixing zone is
inappropriate at the Tulalip Landfill because a mixing zone would
not be protective of organisms that live in the sediments
surrounding the landfill. These species are likely to be
directly exposed to concentrated levels of chemicals from the
leachate seeps when there is no "clean" water available for
mixing when there is a low tide, and at locations where Zone 2
ground water discharges to surface waters.
Explanation of how the State of Washington regards the use
of mixing zones or "dilution zones" at hazardous substance sites
can be found in the MTCA groundwater protection standards
codified at WAC 173-340-720(6)(d)(i), which states as follows:
"(d) At sites where the affected ground water flows
into nearby surface water, the cleanup level may be
based on protection of the surface water. At these
sites, the department may approve a conditional point
of compliance that is located within the surface water
as close as technically possible to the point or points
where ground water flows into the surface water.
Conditional points of compliance may be approved only
if the following requirements are met:
(i) Use of a dilution zone under WAC 173-201-
035 [now WAC 173-201A-100] to demonstrate
compliance with surface water cleanup levels
shall not be allowed."
This is relevant and appropriate for both the leachate that
discharges through the landfill berm directly into surface waters
o'f the state (i.e., the surrounding wetlands), and the leachate
that migrates through the deeper ground water and directly enters
the sloughs (also surface waters). Both of these discharges are
ground water discharges to surface water, and as such the MTCA
regulations would not allow the use of a dilution zone to
demonstrate compliance with the surface water cleanup levels.
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Use of "brackish" water AWQCs. The Respondents also raised
in Dispute Resolution the issue of interpolation of AWQCs for
"brackish" waters, as permitted under WAG 173-201A-060(2). EPA's
final determination in the Dispute Resolution was that the most
appropriate ARARs analysis consistent with CERCLA and the NCP
uses the most stringent of the freshwater or marine criteria to
determine compliance with ARARs in an environment where both
freshwater and marine biota may be present.
Review of the available biological survey data indicates
that primarily marine organisms inhabit the waters surrounding
the Tulalip Landfill. The presence of marine aquatic receptors
in the vicinity of the Landfill is of primary importance in the
selection of relevant and appropriate water quality criteria.
The marine organisms observed near the Site are likely the
primary receptors for off-site contaminant migration. As such,
use of marine criteria for evaluating potential toxicity to these
organisms is the most appropriate and protective approach.
Therefore, EPA determined that interpolating brackish water
quality criteria for this Site is not appropriate.
Use of dissolved metals data for calculating AWQC tinder
State law. A third issue raised by the Respondents in Dispute
Resolution relates to the use of dissolved metals data, as well
as total metals, in calculating Marine Chronic Criteria (MCC)
AWQC under WAC 173-201A-040, footnote dd. This issue involves
several ARARs: Federal Water Quality Criteria (FWQC), state
ambient water quality standards, and state cleanup requirements
promulgated under MTCA. EPA agrees with the Respondents that the
AWQC promulgated by the State, and most recently FWQC, measure at
least some of the water quality criteria using dissolved metals
data. However, WAC 173-340-730 (7) (c) states that "[c]ompliance
with surface water cleanup standards shall be determined by
analyses of unfiltered surface water samples, unless it can be
demonstrated that a filtered sample provides a more
representative measure of surface water quality." The
Respondents did not demonstrate that the filtered samples would
provide a more representative measure of surface water quality.
As such, and based on available information, unfiltered samples
provide a more representative measure of surface water quality at
this Site.
This approach is consistent with EPA's May 4, 1995,
Administrative Stay of specific metals criteria contained in the
National Toxics Rule ("NTR") 60 Fed. Reg. 22228 (May 4, 1995).
The NTR contains numeric water quality criteria for toxic
pollutants and was promulgated by EPA on December 22, 1992, for
the fourteen states that had not adopted sufficient water quality
criteria (of which the State of Washington was one). The NTR
brought those states into compliance with Section 303 (c) (2) (B) of
the Clean Water Act, which required all states to adopt criteria
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for all toxic pollutants. Among the criteria in the NTR were
aquatic life water quality criteria for metals.
At the time the NTR was promulgated, it was EPA's policy to
express metals criteria using total recoverable metal
concentrations. While metals criteria could be implemented by
measuring either total recoverable metal or dissolved metal,
total recoverable metal measurement, being more conservative,
provided a greater level of protection than dissolved metal
measurement. See 60 Fed. Reg, at 22228.
After promulgation of the NTR, EPA continued to address the
issue-of how to best express metals criteria. EPA held a meeting
with invited experts in January 1993 to further elicit comment on
the use of total recoverable versus dissolved metal criteria. On
October 1, 1993, the EPA Office of Water issued guidance (the
"Metals Policy") on the interpretation and implementation of
metals criteria providing that " [i]t is now the policy of the
Office of Water that the use of dissolved metal to set and
measure compliance with water quality standards is the
recommended approach, because dissolved metal more closely
approximates the bioavailable fraction of metal in the water
column than does total recoverable metal." (Underlining added).
See "Office of Water Policy and Technical Guidance on
Interpretation and Implementation of Aquatic Life Metals
Criteria."
A number of plaintiffs brought lawsuits in 1993 challenging
the NTR metals criteria. In settlement of that litigation, EPA
agreed to issue the May 4, 1995, administrative stay of the
numeric aquatic life water quality criteria (expressed as total
recoverable metal). This stay will remain in effect until EPA
promulgates new metals criteria based upon dissolved metal.
However, on page 22230 of the May.4, 1995, administrative
stay, EPA stated the following concerning the Office of Water's
October 1, 1993, "Metals Policy":
"The adoption of the Metals Policy did not change the
Agency's position that the existing total recoverable
criteria published under Section 304(a) of the Clean
Water Act continue to be scientifically defensible.
EPA developed the total recoverable criteria using
high-quality analytical data and are still
scientifically defensible criteria. When developing
and adopting its own standards, a State, in making its
risk management decision, may wish to consider
sediment, food chain effects and other fate-related
issues and decide to adopt total recoverable or
dissolved metals criteria." (Emphasis added).
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Thus, EPA recognizes that using total metals criteria may in some
cases be the best way to quantify the risk posed by exposure to
metals to aquatic life and human health. In this case, EPA has
decided that quantifying total, rather than dissolved, metals
concentrations in leachate seeps is the most appropriate approach
for assessing overall exposure (via all exposure routes including
ingestion and dermal contact) and potential ecological risks to
fish' and invertebrates residing in the vicinity of the Tulalip
Landfill. EPA does not consider the filtered leachate data to
adequately represent the potential risks to these receptors at
this Site, and thus requires that total metals must be used for
assessing such risks and for showing compliance with the ARARs.
Washington State Model Toxics Control Act ("MTCA") --
RCW Chapter 70.105D; WAC Chapter 173-340
MTCA contains numerical cleanup standards for groundwater,
surface water, soils, air, and sediments. The MTCA regulations
that pertain to the Tulalip Landfill are the groundwater and
surface water cleanup standards contained in WAC 173-340-720 and
-730. These regulations address groundwaters and "surface waters
of the state" that are affected or potentially affected by a
release of a hazardous substance to those waters.
WAC 173-340-720 regulations are relevant and appropriate to
this interim remedial action because the purpose of these
regulations is to protect human health and the environment
through the establishment of numeric cleanup standards for
hazardous substances in groundwater and contain prerequisites for
the use of "mixing zones" to determine compliance with these
standards when groundwater discharges to surface waters.
Likewise, the purpose of this interim action is to protect human
health and the environment by minimizing leachate discharges from
the Tulalip Landfill which contain hazardous substances above the
numeric standards in the regulations.
In addition, WAC 173-340-730 regulations are relevant and
appropriate to this interim remedial action because the purpose
of these regulations is to protect human health and the
environment through the establishment of numeric cleanup
standards for surface water. Likewise, the purpose of this
interim action is to protect human health and the environment and
surface water by minimizing leachate discharges from the Tulalip
Landfill which contain hazardous substances above the numeric
standards in the regulations. Thus, EPA believes that the use of
WAC 173-340-720 and -730 are well-suited to the Tulalip Landfill.
This interim action will attain the MTCA ARARs identified
above by effectively stemming the flow of leachate from the
landfill (see the last paragraph of the section above regarding
"State of Washington Water Pollution Control Act/Water Resources
Act") .
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11.2.2 Location-Specific ARARs
Location-specific ARARs are restrictions placed on either
the concentration of hazardous substances or the conduct of
activities performed in certain locations. They may restrict or
preclude certain remedial actions or may apply only to certain
portions of the area of contamination.
U.S. Fish & Wildlife Coordination Act, 16 U.S.C. §§ 661
et sea.
The Fish and Wildlife Coordination Act prohibits water
pollution with any substance which is deleterious to fish, plant
life, or bird life. Contaminated leachate from the Tulalip
Landfill discharges into the surface water surrounding the
landfill, causing potential harm to fish, plant life, and bird
life; therefore, this Act is relevant and appropriate to the
implementation of the selected interim remedial action.
This interim action will attain the requirements of this Act
as the cap will minimize the continued production of leachate
from the Tulalip Landfill and thereby minimize pollution from the
Landfill which may be deleterious to wildlife.
11.2.3 Action-Specific ARARs
Action-specific ARARs are typically technology- or activity-
based requirements or limitations on actions. These requirements
are not triggered by the specific contaminants identified at a
site, but by activities related to the management of these
contaminants.
Landfill Regrading and Capping
Federal Standards for Municipal Solid Waste Landfills, 40
C.F.R. Part 258
•-*>
Minimal Functional Standards ("MFS") for Solid Waste
Handling. WAC Chapter 173-304
The federal regulations governing landfill closure are
codified at 40 C.F.R. Section 258.60. These regulations require
installation of a final cover system that is designed to minimize
infiltration and erosion. This final cover system must be
comprised of an erosion layer underlain by an infiltration layer
as follows:
1) "The infiltration layer must be comprised of a minimum
of 18 inches of earthen material that has a
permeability less than or equal to the permeability of
any bottom liner system or natural subsoils present, or
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a permeability no greater than IxlO"5 cm/sec, whichever
is less, and" (40 C.F.R. Section 258.60(a)(1).
2) "The erosion layer must consist of a minimum of 6
inches of earthen material that is capable of
sustaining native plant growth." (40 C.F.R. Section
258.60(a)(2).
These federal regulations are relevant and appropriate for the
Tulalip Landfill because the regulations address closure of solid
waste landfills and EPA believes their use at the Tulalip
Landfill is well suited.
To the extent that the Washington State MFS are more
stringent than the federal requirements, the MFS will be the ARAR
which must be met at the Site. The Washington State MFS
regulations for solid waste are provided in WAG 173-304. These
regulations require that landfills will be closed to meet the
following criteria at closure:
1) "At least two feet of 1 X 10"6 cm/sec or lower
permeability soil or equivalent shall be placed upon
the final lifts" and that "Artificial liners may
replace soil covers provided that a minimum of fifty
mils thickness is used" (WAC 173-304-460 (3) (e) (i)).
2) "The grade of the surface slopes shall be no less than
two percent" (WAC 173-304-460(3) (e) (ii)) .
3) "Final cover of at least six inches of topsoil be
placed over the soil cover and seeded with grass, other
shallow rooted vegetation or other native vegetation"
(WAC 173-304-460(3) (e) (iii)).
The current State of Washington MFS for landfill closure
under WAC 173-304 are not legally applicable because the Site is
located on Tribal lands where State requirements are not
enforceable. However, the current MFS standards are relevant and
appropriate because the Tulalip Landfill was a disposal site for
solid wastes, and the purpose of WAC 173-304 was to specify
requirements which are suited for use in specifying how landfills
should be closed. The stated purpose of these regulations is
"establishing these standards as minimum standards for solid
waste handling to provide a state-wide consistency and
expectation as to the level at which solid waste is managed
throughout the state." WAC 173-304-010(6). The specific
requirements stated above are well suited to the interim remedial
action to be performed at this Site, and are therefore, relevant
and appropriate requirements.
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This interim action will attain the 40 CFR Part 257
requirements, and the WAC 173-304 requirements through the
installation of a cap which meets or exceeds the specific
technical requirements listed above. The cap will meet or exceed
the Federal closure requirements and the State MFS requirements,
including the requirements for final slopes, cover components,
and.construction measures.
WAC Chapter 173-301 was the State of Washington's old MFS
for solid waste that was effective from 1972 to 1985 and was in
place in 1979. These regulations required that sanitary landfill
surface areas be closed by covering with an equivalent of two
feet of compacted soil that is sloped to allow for surface water
runoff (WAC 173-301-305). The old MFS regulations also required
that the finished surface of the filled area be covered with
adequate tillable soil and seeded with native grasses or other
suitable vegetation (WAC 173-301-306). The WAC 173-301 MFS
regulations are not ARARs for this interim action, as they do not
meet the requirement of being legally in effect at this time
(they are no longer promulgated, instead they have been
superseded by Chapter 173-304 WAC).
Excavation and Filling
Section 402 of the Clean Water Act ("CWA") --33 U.S.C.' '._
§ 1342
Normally, any sort of action to dredge or fill wetlands is
governed by Section 404, not 402, of the CWA. However, in
November 1984, the U.S. Army Corps of Engineers informed the
Tulalip Tribes of the Corps' decision that the landfill capping
activities that the Tribes were undertaking in the 1980's would
fall under the authority of Section 402 of the CWA, not Section
404. The Corps based its reasoning on the fact that the Corps
characterized the Tribes' efforts to install a more effective
cover over the Tulalip Landfill wastes as "an essential feature
of the landfill/wasting operation" at the Site which the Corps
believed was subject to Section 402 of the CWA. Thus, for the
purposes of this interim action, Section 402 of the CWA is the
applicable requirement governing capping activities occurring on
the on-source area of the landfill, not Section 404.
Section 402 of the CWA established the-NPDES permit program,
which governs direct discharges from point sources. The NPDES
permit regulations contain provisions for discharge limitations,
monitoring requirements, and best management practices. Because
this interim action is being conducted entirely on-site, Section
121(e) of CERCLA does not require that a NPDES permit be issued
to cover these on-site discharges. However, this interim action
will meet all substantive requirements of a NPDES permit for any
on-site discharges. Consistent with the requirements of CWA
Section 402, mitigation for the loss of any on-source wetlands
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that may exist on the landfill surface will not be required under
this ARAR.
This interim action will attain the substantive requirements
of Section 402, including NPDES, for the placement of fill on the
on-source area of the landfill during detailed design and
remedial action by minimizing the generation and discharge of
leachate from the landfill source area into surface waters.
Discharges to the off-source area of the Site are not covered
under CWA Section 402 (see the discussion below regarding CWA
Section 404).
Section 404 of the Glean Water Act -- 33 C.F.R. Parts
320 through 330 and 40 C.F.R. Part 230
Section 404 of the CWA regulates the discharge of fill
material into the waters of the U.S., including wetlands. The
guidelines for this program are set forth in 33 C.F.R. Parts 320
through 330 and 40 C.F.R. Part 230, and are established to ensure
that proposed discharges are evaluated with respect to impacts on
aquatic ecosystems. Thus, Section 404 and its implementing
regulations are applicable to any dredge and fill actions
occurring off-source as part of this interim action.
The regulations set up two separate forms of authorization
for the discharge of dredged or fill material into wetlands. The
first are nationwide permits which authorize certain activities
in wetlands if that activity and the permittee satisfy all of the
nationwide permit terms and conditions. Nationwide Permit Number
38 authorizes specific work needed to contain, stabilize, or
remove hazardous and'toxic wastes, provided such work is done,
ordered, or sponsored by a government agency with appropriate
authority. The second form of authorization, an individual
permit, is required for off-source dredge and fill actions if the
Corps of Engineers determines that the activities will result in
more than minimal impacts to the wetlands. Any discharge or fill
material into the wetlands surrounding the Site which are not
authorized in a nationwide permit will require an evaluation in
accordance with Section 404(b)(1) of the CWA and a determination
by EPA regarding compliance with the substantive requirements of
CWA 404 guidelines and the type and level of mitigation
appropriate for the project.
This interim action will attain the substantive requirements
of Section 404(b) for the of the CWA for the off-source areas
during detailed design and remedial action. Discharges to the
landfill surface are not covered under CWA 404 (see the section
above regarding CWA 402).
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Air Emissions
Clean Air Act (42 U.S.C. §§ 7401 et sea.) -- National
Primary and Secondary Ambient Air Quality Standards, 40
C.F.R. Part 50; Washington State Clean Air Act (R.C.W.
70.94); Puget Sound Air Pollution Control Authority
("PSAPCA") Regulations I and III.
These regulations govern emissions of particulates and
certain priority pollutants to the air from on-site sources.
Federal Clean Air Act regulations are applicable for on-site air
emissions for control of dust particles emitted to the air during
remedial activities. Remedial actions that would result in air
emissions will be designed to meet federal air quality standards.
The state Clean Air Act and PSAPCA regulations are relevant and
appropriate requirements. Remedial actions that could involve
releases of contaminants to the air will be performed in
compliance with the substantive requirements of a PSAPCA permit;
however, on-Site actions will not require a PSAPCA permit.
These air emissions requirements will be attained during and
after construction of the interim remedial action. An evaluation
will be conducted to ensure that landfill gas emissions comply
with these requirements.
11.2.4 To Be Considered
The following are not ARARs, but instead are "to be
considered" ("TBC") when implementing the selected remedy.
Detailed design and construction of the interim remedy shall be
consistent with the TBCs as appropriate.
Coastal Zone Management Act ("CZMA"). 6 U.S.C. §§ 1451-
1464; State of Washington Shoreline Management Act
("SMA"). Chapter 90.58 RCW
These statutes impose certain requirements for construction
and development of shorelines. The prerequisite of these
statutes, the presence of shorelines of statewide significance,
including marine waters and wetlands, is met at this Site given
that the Snohomish River Delta has been identified as a shoreline
of state significance.
These statutes are TBC during detailed design and remedial
action.
40 C.F.R. Part 6, Appendix A
40 C.F.R. Part 6, Appendix A implements two Executive
Orders, Executive Order 11988 - "Protection of Floodplains" and
Executive Order 11990 - "Protection of Wetlands"). Normally,
this Appendix would be considered for both the on-source and off-
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source areas of the Site, but because the on-source area is to be
addressed under the requirements of CWA 402, this Appendix is to
be considered for only the off-source areas of the Site. The two
Executive Orders are also TBCs, and are described directly below.
This Appendix is TBC for the off-source areas during
detailed design and remedial action.
Executive Order 11988 - "Protection of Floodplains" and
Executive Order 11990 - "Protection of Wetlands"
These two Executive Orders are implemented by 40 C.F.R. Part
6, Appendix A, which is described directly above. The Executive
Orders direct that actions occurring within floodplains must be
performed so as to avoid adverse impact to the floodplain, and to
minimize potential harm and to restore and preserve the natural
and beneficial values of the floodplain, and that actions
occurring within a wetland must be performed so as to minimize
the destruction, loss, or degradation of wetlands. The
prerequisite for the floodplain Executive Order to apply is that
actions will occur in a floodplain, i.e., lowlands, and
relatively flat areas adjoining inland and coastal waters and
other flood-prone areas. Although the landfill surface is above
the 100 year floodplain, the surrounding wetlands are below the
flood level.
Within and adjacent to wetlands, Executive Order 11990 and
EPA's Wetlands Action Plan direct actions to be performed so as
to minimize the destruction, loss, or degradation of wetlands.
The off-source areas of the Site are ecologically very productive
wetlands that have been classified as wetlands by the Army Corps
of Engineers, therefore, both the wetlands Executive Order and
the Wetlands Action Plan are to be considered in the off-source
area of the Site when implementing the remedy.
These Executive Orders are TBC for the off-source areas
during detailed design and remedial action.
State of Washington Shoreline Management Act ("SMA") ._--_
Chapter 90.58 RCW. WAC Chapter 173-16
WAC 173-16-060(14) directs landfilling in shoreline areas to
be designed such that significant damage to existing ecological
values or natural resources does not occur. In addition, fill
materials should be of such quality that they will not cause
water quality problems and perimeters of fills should be
vegetated or otherwise protected from erosion.
Guidelines for shoreline protection measures (such as
riprapping and other bank stabilization measures) are provided in
WAC 173-16-060(17). Shoreline protection measures should be
located, designed, and constructed to avoid the need for
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channelization and to protect the natural character of the
streamway.
These regulations are TBC for the off-source areas for this
interim action because the actions to be taken as part of the
interim action, excavation and filling, are the same actions
regulated by the SMA and WAC 173-16. In addition, the locations
where the interim action is taking place (e.g., filling of off-
source wetlands for placement of the cap, bank stabilization
measures, and stormwater controls constructed in the off-source
wetlands) are the same locations regulated by the Act and WAC
173-16. Thus, the SMA and WAC 173-16 are TBC.
The SMA and WAC 173-16 are TBCs for the off-source wetlands
during detailed design and remedial action. The interim remedy
shall include shoreline protection measure(s) as appropriate,
during and after construction, to avoid-channelization in the
off-source area and to protect the natural character of the off-
source area.
PSAPCA Guidelines For Acceptable Ambient Levels ("AALs")
These guidelines are not ARARs because they are non-
promulgated guidance, but instead are guidelines to be considered
when implementing the selected remedy. This TBC shall be
considered when remedial actions produce air emissions. The AAL
guidelines specify that actions producing air emissions.must meet
the guidelines. They are used to help implement PSAPCA
Regulation III (see the discussion under "Air Emissions" in
Section 11.2.3 - Action-Specific ARARs), which governs releases
of toxic air pollutants.
These guidelines shall be considered in decision-making
regarding air emissions and the potential need for landfill gas
treatment. .. —
.11.3 COST-EFFECTIVENESS
Cost savings are built into the presumptive remedy approach.
The EPA guidance document "Presumptive Remedies: Policy and
Procedures, EPA 540-F-93-047 (September, 1993) states on page 2:
"Why Should Presumptive Remedies Be Used?
Presumptive 'remedies are expected to have several benefits.
Limiting the number of technologies considered should
promote focused data collection, resulting in streamlined
site assessments and accelerated remedy selection decisions
which achieve time and cost savings. Additional time
savings could be realized during the remedial design since
early knowledge of the remedy may allow technology-specific
data to be collected upfront during the remedial
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investigation (RI). Presumptive remedies will also produce
the added benefit of promoting consistency in remedy
selection, and .improving the predictability of the remedy
selection process for communities and potentially
responsible parties (PRPs)." (underlining added).
In the case of Tulalip Landfill, EPA and the PRPs were able to
achieve cost and time savings by structuring the RI/FS to follow
the presumptive remedy approach. Money and time were saved
because EPA and the PRPs agreed in the RI/FS AOC to focus the
data collection and streamline site assessments. This
early/interim ROD represents accelerated remedy selection, which
translates into time and cost savings.
The cost of the selected interim remedy is proportional to
its overall effectiveness and it represents a reasonable value
for the money to be spent. The selected interim remedy is the
least expensive alternative that meets both of the NCP threshold
remedy evaluation criteria: overall protection of human health
and the environment, and compliance with applicable or relevant
and appropriate requirements.
EPA's total cost estimate for the selected interim
alternative is $25.1 million. This cost estimate reflects the
total cost estimate provided by the Respondents in the Source
Area Containment Feasibility Study ($22.4 million), in addition
to an EPA cost estimate that accounts for the possibility that a
landfill gas treatment system may be necessary ($2.7 million) to
meet emissions requirements of the Puget Sound Air Pollution
Control Authority (PSAPCA).
EPA believes that there is significantly more certainty
associated with the cost estimate for the selected interim remedy
than for some of the other alternatives that did not meet the NCP
threshold criteria, especially Alternatives 2b and 2b(ii), which
the Respondents assert are viable containment alternatives. The
selected interim remedy includes a low permeability landfill
cover system, which is a proven technology for containing
landfill wastes. Materials for landfill covers are, in general,
readily available, and their costs are relatively certain. Low
permeability covers have been installed on hundreds of landfill
sites across the country. Based on EPA's experience with
landfill covers, EPA believes that a properly constructed
landfill covers is likely to effectively contain the waste at the
Tulalip Landfill over the long term with relatively low operation
and maintenance (O&M) costs. Landfill covers have a proven track
record as an effective, relatively low cost remedy for landfill
sites. Following implementation of the landfill cover, there is
relatively little likelihood that the cover would fail to contain
the landfill contaminants, and thus costly contingent actions
will be avoided. Because of the knowledge base that has been
developed regarding landfill covers and their performance, EPA
86
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believes that the cost estimate for the selected interim remedy
is relatively accurate. EPA notes that a significant factor
affecting the cost of the selected interim remedy is the cost of
importing fill to attain the minimum surface slopes required by
the MFS. If the amount or cost of imported fill can be minimized
during detailed design, the actual cost of the selected interim
remedy may be less than the $25.1 million estimate. In addition,
if treatment of landfill gas turns out to be unnecessary, the
total cost estimate for the selected interim remedy falls to
$22.4 million, an estimated savings of $2.7 million.
EPA believes that the cost estimates for Alternatives 2b and
2b(ii), on the other hand, are considerably less certain.
Because the implementability and effectiveness of these
alternatives at a Site like Tulalip Landfill are unknown,39 the
actual cost of implementing either of these alternatives could
turn out to be much higher than the current cost estimates that
have been developed by EPA and the Respondents. In EPA's view,
the significant differences between the Respondents' cost
estimates for Alternatives 2b and 2b(ii) [$13.3 million and $11.8
million, respectively), and EPA's cost estimates for the same
alternatives ($21.3 million and 20.8 million, respectively),
reflect the uncertainty of the cost estimates for these
alternatives, as compared to the relative certainty of the cost
estimate for the selected interim remedy.
EPA's cost estimates for Alternatives 2b and 2b(ii) are
significantly higher than the Respondents' estimates in part
because EPA has attempted to fashion more realistic cost
estimates that take into account some of the uncertainty that is
inherent in these alternatives.40 When EPA's cost estimates for
Alternatives 2b and 2b(ii) are used, it is clear that the costs
for these alternatives are relatively comparable to the cost of
the selected interim remedy. However, even EPA's more realistic
cost estimates could seriously underestimate the actual costs of
implementing 2b and 2b(ii) if unforeseen problems develop which
would require expensive contingent actions to mitigate the
problems. EPA has serious concerns with regard to the potential
implementability and effectiveness of Alternatives 2b and
2b(ii).41 For example, EPA believes that the collection system
proposed for these alternatives could develop serious problems,
such as clogging or plugging of the drainage media in the
39 The Respondents have been unable to identify any other similar
landfill Site where a similar system has been successfully implemented.
40 See interim ROD Appendix A for more information on how and why the
Respondents' and EPA's cost estimates for Alternatives 2b and 2b (ii) differ)
41 See interim ROD Appendix A.
87
-------
collection trenches.42 In the event that the collection system
turns out to be ineffective at containing landfill wastes, or
prohibitively expensive to operate and maintain, it may
eventually be necessary to implement the Alternative 4c cover as
a contingent action, which would significantly raise the total
source area response costs. EPA also has significant concerns
with, regard to the long term effectiveness of the Alternative 2b
treatment berms as they have been proposed for use at this
Site.43
As discussed in the Proposed Plan at page 18, the $170,000
per acre estimate for the selected interim remedy is
significantly less than the average cost per acre found in a
study conducted by the U.S. Department of Defense of a number of
landfills (see the document "Comparison of DOD and EPA/Private
Sector Waste Site Cleanup Efforts" in the administrative record
for this interim ROD). The Department of Defense study concluded
that the actual average cost per acre to remediate the landfills
they studied was $208,000 for landfill remedies implemented by
the Department of Defense, and $294,000 per acre for landfill
remedies implemented by EPA or private parties.
Available information also indicates that the cost per acre
for implementing the selected interim remedy is comparable
(actually somewhat lower) than the average cost per acre for
implementing landfill covers at landfills of similar size. In
comparing the cost per acre of the selected interim remedy with
landfills of similar size where a landfill cover was selected,
the average cost per acre for other landfills exceeds-—
$173, 000,44 versus $170,000 per acre for the selected interim
remedy (see Appendix E of this interim ROD for more information).
Although no two landfills are exactly the same in terms of
acreage and details of the remedy, in general, available
information suggests that the cost per acre predicted for the
selected interim remedy is comparable to or less than the per
acre costs for other landfills.
Because the selected interim remedy is a "passive" system
that does not require any pumps or other active systems, the
42 See interim ROD Appendix D for EPA's specific comments on the
Respondents' proposal for Alternative 2b(ii).
43 See EPA's August 3, 1995 comment letter on Alternative 2b (Eric
Winiecki, EPA, to Anthony Burgess, Colder), in the administrative record for
this interim ROD.
44 This estimate is derived from cost estimates for relevant landfills
from the 30 CERCLA landfill FS Reports that EPA used as the basis for
developing the Feasibility Study for CERCLA Municipal Landfills, September,
1993 .
88
-------
operation and maintenance (O&M) costs for this alternative are
low relative to those predicted for Alternatives 2b and 2b(ii),
which rely on active pumping systems. Lower O&M costs make the
selected interim remedy a more effective remedy for the long
term.
. In summary, EPA believes that the selected interim remedy 4c
is the most cost effective alternative because it is the lowest
cost alternative that meets the two NCP threshold criteria.
Given the proven track record of low permeability covers as
implementable and effective containment remedies at landfill
sites like the Tulalip Landfill, EPA believes that the selected
interim remedy is the least expensive remedy that is most likely
to provide an adequate level of protection at a reasonable cost,
with relatively low risk that the cost estimate for 4c would be
significantly exceeded.
EPA concludes that, relative to Alternatives 2b and 2b(ii),
the selected interim remedy is cost effective because when EPA's
more realistic cost estimates are used, the relative costs of 2b,
2b(ii), and 4c are comparable. In addition:
• EPA believes there is a relatively low level of certainty
with regard to the available cost estimates for Alternatives
2b and 2b(ii);
• EPA has sufficient reason to expect that the actual costs of
these Alternatives 2b and 2b(ii) could turn out to be
significantly higher than the EPA cost estimates for these
alternatives because they employ unproven technologies and
could require expensive contingencies, possibly including
implementation of—a low-permeability cover, to effectively
contain the landfill wastes.
• EPA does not consider Alternatives 2b and 2b(ii) to be
protective of human health and the environment, nor do these
alternatives meet ARARs.45
Given these considerations, EPA concludes that the selected
interim remedy is more cost effective than Alternatives 2b and
2b(ii). In considering the NCP evaluation criteria, the selected
remedy represents the best balance of costs, protectiveness,
permanence, and long-term effectiveness.
11.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE
TREATMENT TECHNOLOGIES TO THE MAXIMUM EXTENT PRACTICABLE
The principal element of the selected remedial action is
containment which will be achieved by installing a low
45 See Section 9.0 - Summary of Comparative Analysis of Alternatives.
89
-------
permeability cap over the landfill. Containment addresses the
primary threat at the Site of infiltration and leachate
generation by minimizing groundwater and seep leachate migration
and achieving all the seep and groundwater RAOs. The integrity
of the cap is less susceptible to settlement-induced cracking,
freeze/thaw cycles, erosion, and biointrusion than a soil cover
and is more reliable. It is expected that minor maintenance will
be necessary to correct vegetation and soil loss due to erosion.
A low permeability cap is implementable as a well known
technology, and is expected to be effective in the long-term.
The passive storm water controls will require minimal maintenance
to ensure proper functioning thereby lending permanence to the
remedial action.
11.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
The presumptive remedy approach for municipal-type landfills
utilizes the remedial approach of containment of wastes rather
than treatment of wastes. The selected interim remedy is
expected to reduce the toxicity and mobility of the waste, and
minimize the generation of new leachate. By minimizing
infiltration of rain water into the landfill, the height of the
leachate mound in Zone 1 will fall. As more of the waste becomes
unsaturated, the rate of "natural" biological degradation of the
waste is expected to increase. Because this interim action does
not constitute the final remedy for the Site, the statutory
preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element may be
addressed by the final response action.
12.0 DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for Interim Remedial Action for the
Tulalip Landfill Superfund Site was released for public comment
on August 7, 1995. The Plan identified Alternative 4c,
Geosynthetic Cover with Passive Drainage, as the preferred
alternative for interim remedial action. The public comment
period closed on October 25, 1995. EPA has considered, at some
point in the CERCLA process, all of the remedy alternatives that
have ever been submitted to EPA by the Respondents, including
Alternatives 2b and 2b(ii), which were submitted after the Source
Area Containment Feasibility Study was approved by EPA. After
the close of the public comment period, EPA re-considered and
re-evaluated all of the alternatives, including-those
alternatives which do not include a landfill cover. EPA reviewed
all written and verbal comments submitted during the public
comment period. Upon review of this information, including these
comments, it was determined that no significant changes to the
remedy, as originally identified in the Proposed Plan, were
necessary.
90
-------
Several non-significant changes occurred between issuance of
the Proposed Plan and the signing of this interim ROD, none of
which required any modifications to the preferred remedy as
described in the Proposed Plan. For example:
• The Proposed Plan stated that Alternative 2b would meet
RAOs. However, upon review of public comments, additional,
more recent technical information,46 and EPA's re-
evaluation of all the remedial alternatives, EPA determined
that Alternative 2b does not meet all of the RAOs that have
been identified for the interim remedial action.
• The ATSDR Preliminary Public Health Assessment for Tulalip
Landfill (June, 1993), which was inadvertently omitted from
the Administrative Record, was added to the Administrative
Record after the public comment period. However, EPA did
not rely on the information in the Preliminary Report
because of the preliminary nature of the report, and because
all of the data on which the report was based was collected
prior to the RI.
• In accordance with the NCP, EPA has added some documents to
the Administrative Record that were generated or received by
EPA during or after the public comment period on the
Proposed Plan.
• After the 80-day public comment period on the Proposed Plan
ended on October 25, 1995, EPA received several letters from
the Respondents transmitting late comments on the Proposed
Plan. EPA has added these late comments to the
Administrative Record for this interim ROD. However, in
accordance with the requirements of the NCP, EPA has
determined that, based on EPA's review of the late comments,
modification of the preferred remedy as.described in the
Proposed Plan was not necessary nor appropriate. EPA has
not provided written responses to the Respondents' late
commejnjts.
• EPA made minor modifications to some of the RAOs as they
were described in the Proposed Plan. EPA added an RAO
("Minimize Infiltration") based on the recommendation of EPA
Presumptive Remedy guidance. See Section 7.0.
46 See "Comparison of the Leachate Collection and Treatment Alternative
(2B) with the FML Cover Alternative (4C)," Colder, October, 1995; Memorandum,
Keith Pine of Weston to Eric Winiecki of EPA, February 7, 1996. See also
Memorandum, Eric Winiecki to The File, August 4, 1995, re: EPA Review of
Alternative 2b - Treatment Berm; Section 9.0 and Appendices A, D and E of
this interim ROD.
91
-------
• Interim ROD Tables 6-1 and 6-2 and Figure 6-1 were updated
from the Streamlined Risk Assessment based on changes EPA
has made to the Region 3 risk-based concentrations for soil
ingestion since the development of the Streamlined Risk
Assessment.
EPA does not consider any of these changes to be significant.
92
-------
Table 1-1: Species of Concern
Species
Bald Eagle (Haliaeetus leucocephalus)
Osprey (Pandion haliaetus)
Great Blue Heron (Ardea herodias)
Arctic Tern (Sterna paradisaea)
Harbor Seal (Phoca vitulina)
California Sea Lion (Zalophus ca.liforn.icus)
Stellar (northern) Sea Lion
(Eumetopias jubatus)
Ball's Porpoise (Phoecoenoides dalli)
Pacific Harbor Porpoise (Phecoena phocoena)
Bull Trout (Salvelinus confluentus)
Sellers Ground Beetle (Agonum belleri)
Yuma Myotis (Myotis yumanensia)
Black Lily (Fritillaria cams cha teens is)
Water Lobelia (Lobelia dortmanna)
Choriso Bog-Orchid (Platanthera chorisiana)
Distance from Site
(if available)
Within 1/4 mile
Within 1/4 mile
Within 1/4 mile
Within 1/4 mile
Within 4 miles
Within 4 miles
Within 4 miles
Within 15 miles
Within 15 miles
State
Status
T
M
M
M
M
M
T
M
C
—
C
S
s
T
Federal
Status
T
—
T
—
—
C
C
C
—
T = Threatened
M = Monitored
C = Candidate for Listing
S = Sensitive
Sources: December, 1987, letter from U.S. Fish and Wildlife Service to Jerry Lee, E&E.
December, 1987, letter from Washington Department of Wildlife to Jerry Lee, E&E.
January, 1988, letter from Washington Department of Natural Resources to Jerry Lee, E&E.
Preliminary Natural Resource Survey, Tulalip Landfill, Marysville, Washington,
National Oceanic and Atmospheric Administration (NOAA), 1991.
February 6, 1996, letter from NOAA to Eric Winiecki, EPA.
-------
Table 5-1
Chemicals Detected in On-Source and Off-Source Media
Analytu
VOCs
1,1-Dichloroethane
2-Butanone
2-Hexanone
4-Methyl-2-Pentanone
Acetone
Benzene
Butylbenzene
Carbon Disulfide
Chlorobenzene
Chloroethane
Chloroform
Chloromethane
cis-1 ,2-Dichloroethene
Ethylbenzene
Methylene Chloride
Toluene
Total Xylenes
Trichloroethene
On-Source Media |
Zone 1 I
Grpundwnter I
X
X
X
X
X
X
Zone 2
Groundwator
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface
.... Watw .
X
X
X
X
X
X
X
Surface
SoiL. I
Off-Source Media
Surface
Soil.. ...
Subsurface
....._ .Soil ..
Surface
.. . _W.ate.L.
Leachate
Seep1
Surface Subsurface
Sediment 1 Sediment
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
BNAs
1 2 4-Trichlorobenzene
1 2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
2,4-Dichlorophenol
2.4-Dimethylphenol
1 -Methylnaphthalene
2-Methylnaphthalene
2-Methylphenol
3,3'-Dichlorobenzidine
4-Chloro-3-methylphenol
4-Methylphenol
I 4-Nitrophenol
Acenaphthylene
Acenapthene
Anthracene
Benzo(a)anthracene
Bonzo(a)pyrone
Benzo(b)lluoranthene
Benzo(q,h,i)perylene
Benzo(k)fluoranthene
Benzole acid
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
r
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
I
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Fish
Tissue
t
-------
Chemicals Detected in On-Source and Off-Source Media (Continued)
Analyte
bis(2-Chloroe.thyl)ether
bis(2-Ethylhexyl)phthalate
Butylbenzylphthalate
Carbazole
Chrysene
Di-n-butylphthalate
Di-n-octylphthalate
Dibenz(a.h)anthracene
Dibenzofuran
Diethvlphthalate
Dimethylphthalate
Fluoranthene
Fluorene
Indenod ,2,3-cd)pyrene
n-Nitroso-diphenylamine
n-Nitroso-di-n-propylamine
Naphthalene
Penlachlorophenol
Phenanthrene
Phenol
Pyrene
On-Source Media
Zone 1
Groundyva.ter_
X
X
X
X
X
X
X
X
Zone 2
Grgurjdwatec
X
X
X
X
X
X
X
X
X
X
Surface
Water
X
X
X
X
X
X
X
X
X
Surface
Soil
X
X
X
X
X
X
X
X
X
Off-Source Media i
Surface
Soil
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Subsurface
Soil
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface
Water
X
X
Leachate
Seep'
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface
Sedirjient
X
X .
X
X
X
X j
X
X
X
X
X ^
X
X
Subsurface I Fish
Sediment I Tissue
X
X
X
x i
X j
X I
X
x .
X
X
X
X
PCB/Pesticides
4.4'-DDD
4.4'-DDE
4.4'-DDT .
Aldrin
Aroclor-1 01 6
Aroclor-1232
Aroclor-1 242
Aroclor-1 248
Aroclor-1 254
Aroclor-1 260
alpha-BHC
beta-BHC
delta-BHC
gamma-BHC (Lindane)
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin
Endrin aldehyde
Endrin ketone
X
X
X
X
X
X
I
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
I x
- -~
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X •
X
X
X
X
•
x
-------
Chemicals Detected in On-Source and Off-Source Media (Continued)
Analyte . .
gamma-chlordane
Heptachlor
Heptachlor epoxide
Methoxychlor
On-So'urce Media
Zone 1
Gr.oun.dj¥atej..
X
Zone 2.
SfQWDdjoateL
X
Surface
_.YMw. .
Surface
Soil...,.
Off-Source Media
Surface
t_ SfiiL_
X
X
Subsurface
_Sj2il__
X
Surface
Water
Leachate
Seep1
X
X
X
X
Surface
Sediment
X
X
X
Subsurface
Sediment
X
INORGANICS
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Calcium
Chromium
Cobalt
Copper
Cyanide
Iron
Lead
Maqnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Sodium
Thallium
Vanadium
Zinc
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
••
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CONVENTIONALS
Ammonia Nitrogen I! X
X
II
1 1 X
Fish
Tissue
X
X
X
X
X
X
X
X
X •
X
X
X
X
X
X
X
X
X
X
X
X
'Summary of on-source and off-source leachate seeps.
-------
Table 6-1
Comparison Numbers Used for the Human Health Evaluation
Analyte
I Soil/Sediment1 |[_ Surface water4
. EPA2
MTCA3
Units ||
Units
VOCs
1,1-Dichloroethane
4-Methyl-2-Pentanone
Aceto'ne
Benzene
Butylbenzene
Chlorobenzene
Chloroethane
Chloromethane
cis-1 ,2-Dichloroethene
Ethylbenzene
Methylene Chloride
Toluene
Total Xylenes
Trichloroethene
200,000,000.00
N/A
200,000,000.00
200,000.00
20,000,000.00
41,000,000.00
820,000,000.00
440,000.00
20,000,000.00
200,000,000.00
760,000.00
410,000,000.00
1,000,000,000.00
520,000.00
32,000,000.00
N/A
32,000,000.00
1,400,000.00
N/A
6,400,000.00
N/A
3,100,000.00
3,200,000.00
32,000,000.00
5,300,000.00
64,000,000.00
640,000,000.00
3,600,000.00
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
N/A
N/A
N/A
71.00
N/A
21,000.00
N/A
N/A
N/A
29,000.00
1,600.00
200,000.00
N/A
81.00
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
BNAs
1 -Methylnaphthalene
1 ,2-Dichlorobenzene
1 ,2,4-Trichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
2-Methylnaphthalene
2-Methylphenol
2,4-Dichlorophenol
2,4-Dimethylphenol
3,3'-Dichlorobenzidine
4-Chloro-3-methylphenol
4-Methylphenol
4-Nttrophenol
Acenaphthylene
Acenapthene
Anthracene
3 enz (a) anthracene
Benzo(a)pyrene
Benzo(b)fluorarrthene
B enzo(g , h, i)pery lene
Benzo(k)fluoranthene
Benzole acid
bis(2-Chloroethyl)ether
bis(2-Ethylhexyl)phthalate
Butylbenzylphthalate
Carbazole
Chrysene
Di-n-butylphthalate
Di-n-octylphthalate
Dibenz(a,h)anthracene
N/A
180,000,000.00
20,000,000.00
180,000,000.00
240,000.00
N/A
100,000,000.00
6,100,000.00
41,000,000.00
13,000.00
N/A
10,000,000.00
130,000,000.00
N/A
120,000,000.00
610,000,000.00
7,800.00
780.00
7,800.00
N/A
78,000.00
1,000,000,000.00
5,200.00
410,000.00
410,000,000.00
N/A
780,000.00
200,000,000.00
41,000,000.00
780.00
N/A
29,000,000.00
3,200,000.00
N/A
1,700,000.00
N/A
N/A
960,000.00
6,400,000.00
89,000.00
N/A
N/A
N/A
N/A
19,000,000.00
96,000,000.00
5,500.00
5,500.00
5,500.00
N/A
5,500.00
1,300,000,000.00
36,000.00
2,900,000.00
64,000,000.00
2,000,000.00
5,500.00
32,000,000.00
6,400,000.00
5,500.00
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
. ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
L ug/kg
ug/kg
ug/kg
N/A
17,000.00
N/A
2,600.00
2,600.00
N/A
N/A
790.00
N/A
0.077
N/A
N/A
N/A
N/A
N/A
110,000.00
0.031
0.031
0.031
N/A
0.031
N/A
1.40
5.90
N/A
N/A
0.031
12,000.00
N/A
0.031
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
96-165.XLS
-------
Table 6-1 - page 2
Analyte
Dibenzofuran
Diethylphthalate
Dimethylphthalate
Fluoranthene
Fluorene
lndeno(1 ,2,3-cd)pyrene
n-Nrtroso-di-n-propylamin*
n-N'rtrosodiphenylamine
Naphthalene
Pentachiorophenol
Phenanthrene
Phenol
Pyrene
Soil/Sediment'
EPA2
. 8,200,000.00
1,000,000,000.00
1,000,000,000.00
82,000,000.00
82,000,000.00
7,800.00
820.00
1,200,000.00
82,000,000.00
48,000.00
N/A
1,000,000,000.00
61,000,000.00
MTCA3 Units
N/A
260,000,000.00
320,000,000.00
13,000,000.00
13,000,000.00
5,500.00
5,700.00
8,200,000.00
1,300,000.00
330,000.00
N/A
190,000,000.00
9,600,000.00
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
Surface water"
N/A
120,000.00
2,900,000.00
370.00
14,000.00
0.031
N/A
16.00
N/A
8.20
N/A
4,600,000.00
11,000.00
Units
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
PCB/Pesticides
4,4'-DDD
4,4'-DDE
4,4'-DDT
Aldrin
alpha-BHC
Aroclor-1016
Aroclor-1232
Aroclor-1242
Aroclor-1248
Aroclor-1254
Aroclor-1260
beta-BHC
delta-BHC
gamma-BHC (Lindane)
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin
Endrin aldehyde
Endrin ketone
gamma-chlordane
Heptachlor
Heptachlor epoxide
Methoxychlor
24,000.00
17,000.00
17,000.00
340.00
910.00
140,000.00
740.00*
740.001
740.00a
41,000.00
740. 00a
3,200.00
N/A
4,400.00
360.00
12,000,000.00"
12,000,000.00"
N/A
610,000.00
N/A
N/A
4,400.00°
1,300.00
630.00
10,000,000.00
170,000.00
120,000.00
120,000.00
2,400.00
6,400.00
22,000.00
5,200.00'
5,200.00'
5,200.00'
5,200.00a
5,200.00'
22,000.00
N/A
31,000.00
2,500.00
N/A
N/A
N/A
96,000.00
N/A
N/A
30,800.00°
8,900.00
4,400.00
1 ,600,000.00
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
0.00084
0.00059
0.00059
0.00014
0.013
0.00005
0.00005
0.00005
0.00005
0.00005
0.00005
0.05
N/A
0.063
0.00014
2.00
2.00
2.00
0.81
0.81
N/A
0.00059°
0.00021
0.00011
N/A
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
INORGANICS5
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Calcium
1,000,000.00
820.00
3.80
140,000.00
1.30
1,000.00
N/A
N/A
130.00
57.00
22,000.00
9.30
6.60
N/A
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
N/A
4.30
0.00014
N/A
N/A
N/A
N/A
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
96-165.XLS
-------
Table 6-1 - page 3
Analyte
Chromium
Cobalt
Copper
Cyanide
Iron •
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Sodium
Thallium
Vanadium
Zinc
Soil/Sediment'
EPA2
10,000.00°
120,000.00
82,000.00
41,000.00
N/A
400.00*
N/A
10,000.00
610.00
41,000.00'
N/A
10,000.00
10,000.00
N/A
N/A
14,000.00
610,000.00
MTCA3
1,600.00°
N/A
12,000.00
6,400.00
N/A
N/A
N/A
45,000.00
96.00
6,400.00'
N/A
1,600.00
1,600.00
N/A
22.00"
2,200.00
96,000.00
Units
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Surface water*
N/A
N/A
N/A
220.00
N/A
N/A
N/A
N/A
0.00015
4.60
N/A
N/A
N/A
N/A
0.0063
N/A
N/A
Units
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
N/A Not Available
1 The lower of the two values (i.e., EPA or MTCA) was used for screening. This Table has been updated since the
streamlined Risk Assessment to reflect recent (1995) revisions to the EPA Region 3 risk-based comparison
numbers for soil. Only the soil comparison numbers have been updated.
2 Values taken from EPA Region III Risk-Based Concentration Table, Fourth Quarter 1994
3 Values taken from Washington State Department of Ecology's Model Toxics Control Act Cleanup Levels
and Risk Calculations Update, January 1995
' Values taken from EPA Water Quality Standards; 40 CFR Part 13V, December 1992
5 Regional background soil concentrations of arsenic and beryllium were also used for comparison.
These values are 90th percentile concentrations obtained from the Washington State Department of Ecology
(Ecology, 1994). The values used were the following:
Arsenic 7.3 mg/kg
Beryllium 0.6 mg/kg
* As "polychlorinated biphenyls"
' As "endosulfan"
e As "chlordane"
" As chromium VI
* Value taken from the Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities
EPA OSWER Directive #9355.4-12, July, 1994
' As "nickel (soluble salts)"
8 As "thallium, soluble salts"
-------
Table 6-2
Summary of On-Source and Off-Source Site Data that Exceed
Human Health Comparison Numbers
Analyte
Frequency of
Exceedences
Surface Soil1
Aroclor-1242
Arsenic
Benzo(a)pyrene
Beryllium
Chrysene
Heptachlor epoxide
2/106
91/93
3/106
2/106
1/106
1/106
Range of
Exceed. Cone.
Criteria
Concentration
Background
Concentration
Units
1000-1900
4.8-47.3
1700-3300
1.70-2.10
6000*
2800
, 740
3.8
780
1.3
5500
630
N/A
7.3
N/A
0.6
N/A
N/A
ug/kg
mg/kg
ug/kg
mg/kg
ug/kg
ug/kg
Location of Samples that
Exceeded Criteria
R1SBSB05A1, R1SBSB09A1
Criteria was exceeded at all sample locations except:
R1SBSB09D1 andR1SBSB091-S2
Background was exceeded at all locations except:
R1SBSB08A1, R1SBSB08B1, R1SBSB08C1, R1SBSB08D1,
R1SBSB08E1, R1SBSB08F1, R1SBSB08G1, R1SBSB08I1,
R1SBSB09A1, R1SBSB09D1, R1-SB-SB09A1-S2,
PM.QRSRnOAl
R1-SB-SB06A1-S2, R1SBSB06A1, R1SBSB08I1
R1SBSB02C1.R1SBSB02I1
R1SBSB08I1
R1-SB-SB06A1-S2
Subsurface Soil2
Aroclor-1242
Arsenic
Benzo(a)pyrene
2/19
17/17
3/20
990-1100
4.2-32.4
990-1500
740
3.8
780
N/A
7.3
N/A
ug/kg
mg/kg
ug/kg
R1SBSB05A2, R1SBSB06A2,
Criteria was exceeded at all sample locations.
Background was exceeded at all locations except:
R 1 SBSB07A2 and R 1 SBSB09A2
R1-SB-SB06A2-S2, R1SBSB06A2, R1SBSB06A3
Surface Water
Arsenic
Dibenz(a,h)anthracene
1/20
1/20
0.0018
0.04
0.00014
0.031
N/A
N/A
mg/L
ug/L
R1-SW-SG24-S2
R1-SW-SG24-S2
Leachate
3,3'-Dichlorobenzidine
4,4'-DDD
4,4'-DDE
4,4'-DDT
1/55
1/33
1/33
9/36
0.4
0.022
0.01
0.013-0.049
0.077
0.00084
0.00059
0.00059
N/A
N/A
N/A
N/A
ug/L
ug/L
ug/L
ug/L
R3LSSP06
R6LSSP06
R6LSSP06
R1LSSP09, R3LSSP03, R3LSSP05, R3LSSP06,
R6LSSP02, R6LSSP03, R6LSSP06, R6LSSP10,
R6LSSP08-S2
-------
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CO CO
—1 —1
T- CO
cc cc
of of
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—1 —1
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CO CO CO
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cc cc cc
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SQ-0_Q-CLCuQ-Q-CLD-
gcococococococococo
55COCOCOCOCOCOCOCOCO
^ T- T-cMco^-inmcDco
^Iccccoccccccccccccc
°- -*
a?
>^
.c
m
UJ
i
CM,
'-Q
CD
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CO
CO
—i
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CM"
CO
CD
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CO
CO
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cc
CM"
CO
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CO
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cc
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p
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co
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CM
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-------
Table 6-2 - page 3
Analyte
Dieldrin
ndeno(1 ,2,3-cd)pyrene
gamma-BHC (Lindane)
gamma-chlordane
Heptachlor
Heptachlor epoxide
Mercury
Thallium
Frequency of
Exceedences
6/35
2/55
1/39
1/33
6/35
25/43
4/50
1/33
Range of
Exceed. Cone.
0.006-0.02
0.20-0.38
0.067
0.006
0.00899-0.022
0.011-0.064
0.00018-0.00038
0.0085
Criteria
Concentration
0.00014
0.031
0.063
0.00059
0.00021
0.00011
0.00015
0.0063
Background
Concentration
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Units
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
mg/L
mg/L
Location of Samples that
Exceeded Criteria
R4LSSP06, R6LSSP03, R6LSSP04, R6LSSP06,
R6LSSP08, R6LSSP11
R3LSSP03, R4-LS-SP06-S2
R1LSSP09
R6LSSP11
R1LSSP11, R2LSSP08, R6LSSP02, R6LSSP04,
R6LSSP06, R6LSSP10
R1 LSSP03, R1 LSSP04, R1 LSSP05, R1 LSSP07,
R2LSSP06, R3LSSP03, R3LSSP05, R3LSSP06,
R3LSSP10, R4LSSP03, R4LSSP05, R4LSSP06,
R4LSSP09, R4LSSP10, R6LSSP01, R6LSSP02,
R6LSSP03, R6LSSP04, R6LSSP05, R6LSSP06,
R6LSSP07, R6LSSP08, R6LSSP09, R6LSSP10,
R6LSSP11
R1LSSP08, R2LSSP08, R4-LS-SP06-S2
R5LSSP02
R6LSSP08
Surface sediment
Arsenic
Benzo(a)pyrene
Manganese
52/52
1/52
1/52
8.9-94.4
570
9690
1.6
390
5100
N/A
N/A
N/A
mg/kg
ug/kg
mg/kg
Criteria was exceeded at all sample locations
R1SDSG13
R1SDSG19
Subsurface sediment
Arsenic
20/20
8.8-60.9
1.6
N/A
mg/kg [Criteria was exceeded at all sample locations
Value exceeded MTCA Method C criteria, but did not exceed EPA criteria
This table has been updated since the streamlined Risk Assessment to reflect recent (1995) revisions to the EPA Region 3 risk-based comparison numbers for soil. The
resulting changes to this table are minor and do not change any of EPA's conclusions in or regarding the streamlined Risk Assessment. Changes in this table include:
for site surface soil data, there are no exceedances of Region 3 risk-based soil comparison numbers for Aroclor-1248, benz(a)anthracene, benzo(b)fluoranthene, and
dibenz(a,h)anthracene; the surface soil frequency of exceedance for six other chemicals changed slightly; for subsurface soils, there were slight changes in the reported
frequencies of exceedance for some chemicals. However, no chemicals were removed from the list.
-------
Table 6-3
Comparison Numbers Used for the Ecological Evaluation
Analyte
VOCii
1,2-Dichloroethann
Acetone
1 Benzene
[Chlorobenzene
| Chloroform
Ethylbenzene
1 Toluene
2,4-Dinitrotoluene
1,1,1-Trichloroethane
1,1,2-Trichloroethane
1 1 , 1 ,2,2-Tetrachloroethan8
I Carbon Tetrachloride
[Chloromethane
cis-1 2-Dichloroethene
i trans-1,2-DichloroethenB
JTetrachloroethene
i Trichloroethene
Soil3 II • Sediment | ' Surface Water-Marine
Criteria j Units ||_ ^Criteria L Units 1 Ref 1 Criteria 1 Units
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
Not available
Not available
Not available
Not available
Not available
10
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
AET
Reference
Surface Water-Fresh4
Criteria Units Reference
113000
Not available
700
129
Not available
430
5000
370
Not available
Not available
Not available
50000
6400
224000
224000
450
2000
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
AWQC Acute
AWQC Chronic
AWQC Chronic •
AWQC Acute
AWQC Chronic
AWQC Chronic
AWQC Acute
AWQC Chronic
AWQC Acute
AWQC Acute
AWQC Chronic
AWQC Chronic
20000
Not available
5300
50
1240
32000
17500
230
18000
9400
2400
35200
11000
11600
11600
840
21900
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
WQC Chronic
AWQC Acute
AWQC Chronic
AWQC Chronic
AWQC Acute
AWQC Acute
AWQC Chronic
AWQC Acute
AWQC Chronic
AWQC Chronic
AWQC Acute
AWQC Acute
AWQC Acute •
AWQC Acute
AWQC Chronic
AWQC Chronic
IBNAs
1 2 4-Trichlorob9nzene
i 1 2-Dichlorobenzene
I 1,3-Dichlorobenzcne
I 1 4-Dichlorobenzene
2,4-Dimethylphenol
2-Methylnaphthalene
2-Methylphenol
4-Methylphenol
Acenaphthylene
Acenapthene
i Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluorantheno
Benzo(k)tluoranthene
! Benzo(g,h,i)perylene
Benzole acid
I bl3(2-Elhylli
B_utylbenzylphthalat8
| Chrysene
Di-n-butylphthalate
! Di-n-octylphthalate
Not available
Not available
Not available
Not available
Not available
2.6
Not available
Not available
1100
1100
56000
56000
56000
56000
11000.
56000
Not available
6500
1 60000
i 56000
14000
Not available
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg _
ug/kg
ug/kg
ug/kg
ug/kg
51
50
170
110
29
670
63
670
1300
500
960
1600
1600
3600
3600
720
650
1300
900
2800
1400
6200
ug/kg-dw •
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/Kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
Not available
1970
1970
1970
Not available
300
Not available
Not available
300
710
300
300
300
300
300
300
Not available
360
Not available
300
Not available
Not available
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
_.__E9/L .....
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Chronic
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Chronic
AWQC Acute
Not available
763
763
763
2120
Not available
Not available
Not available
Not available
520
Not available
Not available
Not available
Not available
Not available
Not available
Not available
160
Not available
Not available
Not available
Not available
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Acute
AWQC Chronic
AWQC Chronic
-------
Table 6-3 -
page 2
I Analyte
Dibenz(a,h)anlhracuno
Dlbenzoturari
Diethylphthalate
FluoranthGne
Fluorene
Ind3no(i,2,3-cd)pyrene
n-Nitrosdiphenylamine
Naphthalene
Psntachlorophenol
i Phenanthrene
Phenol
I Pyrene
4-Chlorophenol
2-Chlorophenol
Hexachlorobutadiene
Hexachlorocyclopentadiene
Hexachloroethane
Hsxachlorobenzene
Isophorone
4-Chloro-3-methylphenol
2,4,5-Trichlorophenol
2,4,6-Trichlorophonol
2,4-Dichlorophenol
Soil3
Criteria
1100
Not available
220000
56000
1100
56000
Not available
3900
320
20000
Not available
56000
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Units
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
Sediment |
Criteria
230
540
200
2500
540
690
28
2100
360
1500
420
3300
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Units
ug/kg-dw
ug/kjj-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
Ref J
AET
^'AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
AET
Surface Water-Marine
Criteria
300
Not available
Not available
16
300
300
3300000
2350
7.9
4.6
5800
300
29700
Not available
. 32
7
940
Not available
Not available
Not available
Not available
Not available
Not available
Units
ugA.
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Reference
AWQC Acute
AWQC Chronic
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Chronic
AWQC Chronic /p/
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
AWQC Acute
Surface Water-Fresh4 j]
Criteria Units Reference |
Not available
Not available
Not available
3980
Not available
Not available
5850
620
13.0
6.3
2560
Not available
Not available
4380
9.3
5.2
540
3.68
117000
30
63
970
365
JJO./L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
_ys/k_
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L .
ug/L
ug/L
ug/L
AWQC Acute
AWQC Acute
AWQC Chronic
AWQC Chronic
AWQC Chronic /p/
AWQC Chronic
AWQC Acute
AWQC Chronic
AWQC Chronic
AWQC Chronic I
AWQC Chronic /p/
AWQC Acute
AWQC Acute
AWQC Chronic /p/
AWQC Chronic
AWQC Chronic
PCBa/Pesllcldes
4,4'-DDD
4.4'-DDE
[4,4'-DDT
Aldrin
[RGBs' I
I Oieldrin
iEndosulfan II
llEndrin
gamma-BHC (Lindane)
Heptachlor
Heplachlor epoxids
Mathoxychlor
Chlordano
Endosullan I
Toxaphene
ialpha-BHC
ibata-BHC
Not available
Not available
6.5
Not available
170
11
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg
ug/kg_
ug/kg
ug/kg
ug/kg
ug/kg
16
9
34
Not available
1000
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
Not available
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
ug/kg-dw
AET
AET
AET
AET
3.6
14
0.001
0.0019
0.03
0.0019
0.0087
0.0023
0.16
0.0036
0.0036
0.03
0.004
0.0087
0.0002
0.34
0.34
ug/L _,
ug/L
ug/L
ug/L
ug/L
ug/L
ugtL
ug/L
ug/L
ug/L
ug/L
ug/L
_..M/l- ..
ug/L
.ug/L
ug/L
_J!84- ...-
AWQC Acute
AWQC Acute
AWQC Chronic
WA State Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Acute
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Acute '
AWQC Acute
0.6
1050
0.001
0.0019
0.014
0.0019
0.056
0.0023
0.08
0.0038
0.0038
0.03
0.0043
0.056
0.0002
100
100
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
AWQC Acute
AWQC Acute
AWQC Chronic
WA State Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Acute
AWQC Acute
-------
Table 6-3 - page 3
Analyte
(h)lln BI-IC
•INORGANICS2
>j Aluminum
'i Anlirnony
l! Arsenic
:' Barium
!! Beryllium
: Cadmium
!; Chromium (V1)
i1 Cobalt
: Copper
'". Cyanide
!: Iron
11 Lead
" Manganese
I; Mercury
;! Nickel
|i Selenium
j! Silver
|t
i! Thallium
! Vanadium
;i Zinc
Soil3
Criteria
Not avnilnblo
50
5
30
500
10
5
100
50
100
Not available
Not available
200
1200
2
100
10
2
1
60
67
Units
ug/kg
my/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Sediment
Criteria [ Units
Not available
Not available
150
57
Not available
Not available
5.1
260
Not available
390
Not available
Not available
450
Not available
0.59
140
Not available
6.1
Mot available
Not available
410
'jg/kg-dw
- - - -
mg/kg-dw
mg/kg^dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw ,
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
mg/kg-dw
Ret
Surface Water-Marine j Surtace Water-Fresh4 |
Criteria [ Units
Reference j Criteria Units Reference ||
|l 0.34J ug/L AWQC Acute ] 100 [ ug/L AWQC Acute j
I
ABT
...AET.__
AET
i_ AET
AET
AET
AET
AET
AET
AET
Dissolved/Total
Not available
•0.5
0.036
Not available
Not available
0.0093
0.05/0.05
Not available
0.0024/0.0029
0.001
Not available
0056/0.0085
Not available
0.000025
0.0082/0.0083
0.071
0.0023
2.13
Not available
0.0081/0.086
mg/L
mg/L
mg/L
mg/L .
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
DIssolved/Totat
1
AWQC Chronic /p/
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Acute .
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic /p/
AWQC Acute
AWQC Chronic
Not available
mg/L
0.03j_ mg/L
0.19 i mg/L
Not available I mg/L
0.0053
0.001/0.001 1
0.01/0.1 1
Not available .
0.011/0.012
0.0052
1.0
0.0025/0.0032
Not available
0.000012
0.16
0.005
D.0019/0. 00092
0.04
Not available
0.11
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
AWQC Chronic /p/
AWQC Chronic
AWQC Chronic
LAWQC Chronic
AWQC Chronic I
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Chronic
AWQC Acute /p/
AWQC Chronic
AWQC Chronic
! CONVENTIONAL^ . . . _
<; Ammonia J[ Not available
mg/L JLNot Available
mg/kgj;^
0.035
mg/L IWA State Chronic
0.045
mg/L |WA State Chronic J
'Aroclors 1016. 1221. 1232, 1242, 1248, 1254, 1260
2AWQC criteria for inorganics are the same for dissolved or total metals except where a slash indicates otherwise. In this case, the first value is the dissolved criterion value.
3Soil references listed in Table A-1. Regional background values were also compared to exceedances for inorganics.
•'All AWQC calculations are based on a pH of 7.8 and hardness of 100 ppm CaCO3.
/p/ proposed criteria
-------
Table 6-4
Summary of On-Source Data that Exceed
Ecological Comparison Numbers
Analyte
Frequency of
Exceedances'
Range of Exceed.
Cone.
Criteria
Value
Units
Sample ID of Criteria Exceedances
Surface Soil
bis(2-Ethyhexyl)phthalate
1/5
7200
6500
ng/kg
EE01-SS-P2.
Surface Water
Phenanthrene
Cadmium-total
Chromium-total
Lead-total
Nickel- total
bis(2-ethylhexyl)phthalate
Copper-total
Iron-total
Zinc-total
1/5
1/5
2/5
2/5
3/5
1/5
- 4/5
5/5
4/5
14
0.011
0.938-0.95
0.428-0.486
0.36-0.856
180
0.0145-0.337
' 2.79-44.4
0.506-1,73
6.3
0.0011
0.21
0.0032
0.16
160.0
0.012
1.0
0.11
M9/L
mg/L
mg/L
mg/L
mg/L
ug/L
mg/L
mg/L
mg/L
EE01-SW-P1
EE01-SW-P3 ' '
EE01-SW-P1. EE01-SW-P2
EE01-SW-P1, EE01-SW-P2
EE01-SW-P1, EE01-SW-P3, EE01-SW-P4
EE01-SW-P2
EE01-SW-P1, EE01-SW-P2, EE01-SW-P3, EE01-SW-P4
EE01-SW-P1, EE01-SW-P2, EE01-SW-P3, EE01-SW-P4, EE01-SW-P5
EE01-SW-P1, EE01-SW-P2, EE01-SW-P3, EE01-SW-P4
Zone 1 Groundwater
Chromium-total
Chromium-dissolved
Copper-total
Cyanide-total
Lead-total
Nickal-total
Nickel-dissolved
1/4
1/2
2/4
2/4
3/4
1/4
1/2
0.165
0.153
0.0139-0.0395
0.011-0.016
0.033-0.141
0.0349
0.0277
0.05
0.05
0.0029
0.001
. 0.0085
0.0083
0.0082
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
R1GWTB10
R1GWTB10
R1GWMW23, R1GWTB10
R1GWMW21, R1GWTB10
R1GWMW21, R1GWMW23, R1GWTB10
R1GWTB10
R1GWTB10
-------
Table 6-4 - page 2
Analyta
Zinc-total
Heptachlor Epoxide
Phenanthrene
Ammonia nitrogen
Frequency of
Exceedances1
2/4
2/4
1/4
4/4
Range of Exceed.
Cone.
0.0896-0.961
0.027-0.049
12
12-94
Criteria
Value
0.086
0.0036
• 4.6
0.035
Units
mg/L
H9/L
H9/L
mg/L
Sample ID of Criteria Exceedances
R1GWMW21, R1GWTB10
R1GWMW22, R1GWMW23
R1GWMW23
R1GWMW21, R1GWMW22, R1GWMW23, R1GWTB10
Zone 2 Groundwater
Heptaohlor
Endosulfan II
Zinc-total
Mercury-total
Copper-total
Chromium-total
Lead-total
Cyanide-total
Nickel-total
Phenanthrene
Chromium-dissolved
Lead-dissolved
1/22
1/22
1/87
1/86
4/87
12/87
8/87
7/26
26/87
1/46
5/J1
2/31
0.025
0.033
0.1
0.00021
0.003-0.0069
0.066-0.984
0.0097-0.149
0.005-0.049 .
0.0085-0.32
7
0.115-0.645
0.0088-0.0166
0.0036
0.0087
0.086
0.000025
0.0029
0.05
0.0085
0.001
0.0083
4.6
0.05
0.0056
H9/L
M9/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
H9/L
mg/L
mg'L
R1GWMW14--S2
R1GWMW14-S2
R1GWMW14-S2
R6GWMW08-S2
R4GWMW02, R4GWMW08, R4GWTB06, R6GWMW08-S2
R1GWMW14-S2, R1GWMW14, R1GWMW15, R1GWTB06, R2GWTB06, R3GWMW07-S2,
R3GWMW07, R3GWTB06, R4GWTB06-S2, R4GWTB06, R5GWTB06. R6GWTB06
R1GWMW14-S2, R1GWMW14, R2GWMW04, R3GWT806, R6GWTB06. R6GWMW03, R6GWMW04,
R6GWMW05
R1GWMW14-S2, R1GWMW13, R1GWMW14, R1GWTB01. R1GWTB06. R2GWMW05-S2,
R5GWTB03-S2
R1GWMW14-S2, R1GWMW08, R1GWMW14, R1GWMW15, R1GWTB06, R2GWMW03,
R2GWMW08, R2GWTB06, R3GWMW05, R3GWMW07, R3GWMW08, R3GWMW09, R3GWTB03.
R3GWTB06, R4GWTB06-S2, R4GWMW08, R4GWTB06, R5GWMW03, F5GWMW08, R5WMW10. '
R5GWTB03, R5GWTB06, R6GWMW08-SC, R6GWMW06, R6GWMW08. R6GWTB06
R1GWMW14-S2
R1GWMW14, R1GWMW15, R4GWTB06-S2, R5GWTB06, R6GWTB06
R6GWMW08, R6GWMW03
-------
Table 6-4 - page 3
Analyte
Mercury-dissolved
Nickel-dissolved
Zinc-dissolved
Ammonia nitrogen
Frequency of
Exceedances'
1/30
9/31
1/31
80/80
Range of Exceed.
Cone.
0.00021
0.01-0.286
0.025
0.65-340
Criteria
Value
0.000025
0.0082
0.0081
0.035
Units
mg/L
mg/L
mg/L
mg/L
Sample ID of Criteria Exceedances
G6GWMW08-S2-F
R1GWMW14, R1GWMW15, R5GWMW08, F5GWMW09, R5GvVTB03, R5GWTB06,
R6GWMW08-S2-F, R6GWMW08, R6GWTB06
R6GWMW08-S2-F
All sample locations •
Leachate Seep SP01
Phenanthrene
Iron-dissolved
Lead-dissolved
Cyanide-total
Iron-total
Lead-total
Heptachlor epoxide
Aroclor-1016
Ammonia nitrogen
4/4
4/4
2/2
2/4
4/4
4/4
1/2
1/2
4/4
8-12
15.3-21.7
0.0067-0.01 1
0.017-0.027
18.2-25.1
0X1456-0.0618
0.013
1.2
140-180
6.3
1.0
0.0025
0.0052
1.00
0.0032
0.0038
0.014
0.045
M9/L
mg/L
mg/L
mg/L
mg/L
mg/L
M9/L
H9/L
mg/L
R1LSSP01, R2LSSP01, R5LSSP01. R6LSSP01
R1LSSP01, R2LSSP01. R5LSSP01, R6LSSP01
R5LSSP01, R6LSSP01
R5LSSP01, R6LSSP01
R1LSSP01, R2LSSP01, R5LSSP01, R6LSSP01
R1LSSP01, R2LSSP01, R5LSSP01, R6LSSP01
R6LSSP01
R5LSSP01
R1LSSP01, R2LSSP01, R5LSSP01, R6LSSP01
'Note: The Irequency of exceedances are based on the number ol hits.
-------
Table 6-5
Summary of Off-Source Data that Exceed
Ecological Comparison Numbers
Analyte
Frequency of
Exceedances
Range of
Exceed. Cone.
Criteria
Value
Background
Cone.
Units
Sample ID of Criteria Exceedances
Leachate
Fluoranthene
Phenanthrene
Aldrin
4,4'-DDT
Endrin
Heptachlor
Heptachlor epoxide
Methoxychlor
Aroclor-1016
Aroclor-1232
Aroclor-1254
Chromium-total
2/57
26/58
10/41
10/38
• 7/39
6/39
26/45
2/37
9/39
10/40
1/40
19/60
30-51.1
5-276
0.007-0.036
0.013-0.049
0.012-0.043
0.0089-0.022
0.005-0.064
0.049-0.071
0.47-1.19
1-5.82
1.31
0.0625-0.392
16
4.6
0.0019
0.001
0.0023
0.0036
0.0036
0.03
0.03
0.03
0.03
0.05
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A.
N/A
N/A
N/A
ra/L
H9/L
H9/I-
H9/L
H9/L
M9/1-
H9/L
H9/L
H9/L
H9/L
H9/L
mg/L
R4-LSSP06-S2, R4LSSP06
R1-LS-SP04-3/8, R1-LS-SP04-S2, R1LSSP03, R1LSSP04, R1LSSP06, R1LSSP07.
R2LSSP03, RSLSSP04, R2LSSP06, R2LSSP07. R3LSSP03, R3LSSP06, R4-LSS-
SP06-S2. R4LSSP03, R4LSSP06, R5LSSP03, R5LSSP04, R5LSSP06, R6LSSP03.
R6LSSP04, R6LSSP06, R6LSSP07, R6LSSP08, R6LSSP02, R3LSSPOOR1.
R6LSSPOOR1
R1LSSP03. R1LSSP09, R1LSSP11. R2LSSP08, R3LSSP06. R3LSSP09, R3LSSP10.
R6LSSP08, R6LSSP10, R3LSSPOOR1
R1LSSP09, R3LSSP03, R3LSSP05, R3LSSP06, R6-LSSP08-S2. R6LSSP02,
R6LSSP03, R6LSSP06. R6LSSP10, R3LSSPOOR1
R2LSSP08. R3LSSP06, R4LSSP05, R4LSSP06. R5LSSP03, R6LSSP02, R6LSSP08
R1LSSP11, R2LSSP08, R6LSSP02, R6LSSP04, R6LSSP06, R6LSSP10
R1LSSP03, R1LSSP04, R1LSSP05, R1LSSP07. R2LSSP06, R3LSSP03, R3LSSP05,
R3LSSP06, R3LSSP10, R4LSSP03, R4LSSP05, R4LSSP06, R4LSSP09, R4LSSP10.
R6LSSP11, R6LSSP05, R6LSSP06, R6LSSP07, R6LSSP08, R6LSSP09. R6LSSP10.
R6LSSP03, R6LSSP04, R3LSSPOOR1, R4LSSPOOR1, R6LSSP02
R1LSSP09, R6LSSP06
R5LSSP02, R5LSSP04, R5LSSP06, R5LSSP11, R6LSSP08-S2. R6LSSP02,
R6LSSP05, R6LSSP06, R6LSSP10
R5-LS-SP09-S2, R5LSSP03, R5LSSP05, R5LSSP08, R5LSSP09. R5LSSP10, R6-
LSSP08-S2, R6LSSP07, R5LSSPOOR1, R6SSPOOR1
R6LSSP08-S2
R1LSSP03, R1LSSP06. R1LSSP11, R2LSSP03, R2LSSP05, R2LSSP06. R2LSSP11.
R3LSSP03, R3LSSP05, R3LSSP06, R3LSSPOOR1, R4-LS-SP06-S2, R4LSSP03.
R4LSSP05, R4LSSP06, R5LSSP03. R5LSSP06, R6LSSP03. R6LSSP06
-------
Table 6-5 - page 2
Analyte
Copper-total
Cyanide-total
Lead-total
Mercury-total
Nickel-total
Zinc-total
Dieldrin
Endosultan 1
Chromium-dissolved
Frequency of
Exceedances
25/60
13/53
43/60
4/52
35/60
24/60
6/39
3/39
7/26
Range of
Exceed. Cone.
0.0035-0.069
0.011-0.031
0.0111 0.289
0.00018-0.00038
0.0095-0.1
0.0868-0.24
0.006-0.02
0.0089-0.016
0.0688-0.32
Criteria
Value
0.0029
0.001
0.0085
0.000025
0.0083
0.086
0,0019
0.0087
0.05
Background
Cone.
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Units
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
H9/L
WJ/L
mg/L
Sample ID of Criteria Exceedances
R1-LS-SP04-3/8, R1-LS-SP04-S2, R1LSSP08, R1LSSP11, R2-LS-SP10-S2,
R2LSSP03, R2LSSP04, R2LSSP05, R2LSSP08, R2LSSP11, R3LSSP03, R3LSSP05,
R3LSSP06, R4-LS-SP06-S2. R4LSSP03, R4LSSP05, R5LSSP02, R5LSSP03,
R5LSSP04. R5LSSP05, R5LSSP11, R5LSSP06, R6LSSP11, R.6LSSP08-S2,
R3LSSPOOR1
R2LSSP06, R2LSSP08, R3LSSP05, R3LSSP06, R3LSSP09, R4LSSP03, R4LSSP09,
R5LSSP02, R5LSSP03, R5LSSP05, R5LSSP06, R5LSSP11, R3LSSPOOR1
R1-LS-SP04-3/8, R1-LS-SP04-S2, R1LSSP02, R1SSP03, R1LSSP04, R1LSSP05,
R1LSSP06, R1LSSP07, R1LSSP08, R1LSSP11, R2LSSP03, R2LSSP04, R2LSSP05,
R2LSSP06, R2LSSP07, R2LSSP08, R2LSSP11, R3LSSP03, R3LSSP05, R3LSSP06,
R4-LS-SP06-S2, R4LSSP06, R5LSSP01, R5LSSP02, R5LSSP03, R5LSSP04,
R5LSSP05, R5LSSP06, R5LSSP08, R5LSSP11, R6LSSP08-S2, R6LSSP01,
R6LSSP02, R6LSSP03, R6LSSP04, R6LSSP05, R6LSSP06, R4LSSP03. R4LSSP05,
R6LSSP08, R6LSSP11, R3LSSPOOR1, R6LSSPOOR1, R6LSSP07
R1LSSP08, R2LSSP08, R4-LS-SP06-S2, R5LSSP02
R1-LS-SP04-3/8, R1LSSP02, R1LSSP03, R1LSSP05, R1LSSP06, R1LSSP07,
R1LSSP08, R1LSSP11, R2LSSP03, R2LSSP05, R2LSSP06, R2LSSP07, R2LSSP08,
R2LSSP11, R3LSSP03, -R3LSSP05, R3LSSP06, R4-LS-SP06-S2, R4LSSP03,
R6LSSP11, R4LSSP05, R4LSSP06, R5LSSP02, R5LSSP03, R5LSSP05, R5LSSP06,
R5LSSP08, R5LSSP11, R6LSSP02, R6LSSP03, R6LSSP05, R6LSSP06, R6LSSP07,
R3-LSSPOOR1, R6LSSPOOR1
R1LSSP03, RtLSSPOS, R1LSSP11, R2LSSP03, R2LSSP05, R2LSSP06, R2LSSP08,
R2LSSP11, R3LSSP03, R3LSSP05, R3LSSP06, R4-LS-SP06-S2, R4LSSP03,
R4LSSP05, R4LSSP06, R5LSSP02, R5LSSP03, R5LSSP04, R5LSSP05, R5LSSP06,
R5LSSP08, R5LSSP11, R6LSSP11, R3LSSPOOR1
R4LSSP06, R6LSSP03, R6LSSP04, R6LSSP06, R6LSSP08, R6LSSP11
R4LSSP03. R4LSSP05, R6LSSP09
R4-LSSP06-S2-F, R4LSSP03, R4LSSP05, R4LSSP06, R5LSSP03, R5LSSP06,
R6LSSP06
-------
Table 6-5 - page 3
Analyte
Copper-dissolved
Lead-dissolved
Nickel-dissolved
Zinc-dissolved
Ammonia nitrogen
gamma-chlordane
Frequency of
Exceedances
6/23
6/26
14/19
9/26
46/46
1/36
Range of
Exceed. Cone.
0.016-0.0509
0.0057-0.0353
0.0086-0.11
0.012-0.147
27-180
0.006
Criteria
Value
0.0024
0.0056
0'.0082
0.0081
0.035
0.004
Background
Cone.
N/A
N/A
N/A
N/A
N/A
N/A
Units
mg/L
mg/L
mg/L
mg/L
mg/L
H9/L
Sample ID of Criteria Exceedances
R4-LS-SP06-S2-F, R4LSSP03, R4LSSP05, R5LSSP05, R5LSSP06, R5LSSP11
R4-LS-SP06-S2-F, R4LSSP06, R5LSSP05, R5LSSP06, R6LSSP06, R6LSSP11
R4LSSP06-S2-F, R4LSSP05, R4LSSP06, R5LSSP05, R5LSSP06, R5LSSP08,
R5LSSP11, R6LSSP02, R6LSSP03, R6LSSP05. R6LSSP06, R6LSSP07, R6LSSP08,
R6LSSP11
R4LSSP03, R4LSSP06, R5-LSSP09-S2-F, R5LSSP02, R5LSSP05 R5LSSP06, •
R5LSSP08, R5LSSP11. R6-LS-SP08-S2-F
All sample locations
R6LSSP11
Surface Soil
2-Methylnaphthalene
Acenaphthene
bis(2-Ethyhexyl)phthalato
Fluorene
Naphthalene
Phenanthrene
Aroclor-1242
Aroclor-1260
4,4'-DDT
13/106
5/106
4/106
6/106
4/106
2/106
4/106
3/106
1/106
72-68000
1300-41200
7600-14300
1100-44200
7300-64700
84000-105000
470-1900
340-1100
110
2.6
1100
6500
1100
3900
20000
170
• 170
6.5
N/A
N.'A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
M/kg
H9/kg
. M9/kg
H9/kg
ng/kg
ng/kg
H9/kg
i-'g/kg
pg/kg
R1-SB-SB01C1-S2, R1-SB-SB04A1-S2, R1-SB-SB06A1 -S2. R1 SB-SB08A1-S2, R1-
SB-SB09A1S2. R1SBSB02A1, R1SBSB03A1, R1SBSB04A1. R1SBSB06A1,
R1SBSB08A1, R1SBSB08B1, R1SBSB08C1, R1SBSB09A1
R1-SB-SB06A1-S2. R1-SB-SB09A1-S2, R1SBSB02A1, R1SBSB06A1, R1SBSB09A1
R1-SB-SB06A1-S2. R1-SB-SB08A1-S2, R1SBSB05H1, R1SBSB08G1
R1-SB-SB06A1-S2, R1-SB-SB09A1-S2, R1SBSB02A1, R1SBSB06A1, R1SBSB09A1,
R1SBSB09D1
R1-SB-SB06A1-S2. R1-SB-SB09A1-S2, R1SBSB06A1, R1SBSB09A1
R1-SB-SB06A1-S2. R1SBSB06A1
R1SBSB05A1, R1SBSB06A1. R1SBSB09A1. R1SBSB09D1
R1-SB-SB08A1-S2. R1SBSB06A1, R1SBSB08A1
R1-SB-SB08A1-S2
-------
Table 6-5 - page 4
Analyte
Aluminum
Arsenic
Barium
Chromium
Cobalt
Copper
Lead
Manganese
Vanadium
Frequency of
Exceedances
106/106
11/93
3/106
2/106
1/106
2/106
7/106
10/106
45/106
Range of
Exceed. Cone.
2640-33800
30.6-47.3
788-1650
151-174
97.7
129-135
223-335
1230-3620
60.3-78.9
Criteria
Value
50
30
500
100
50
100
200
1200
60
Background
Cone.
32,581
7.30
N/A
48.15
N/A
36.36
16.83
1146
N/A
Units
nig/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Sample ID of Criteria Exceedances
All sample locations exceed criteria value. However, all locations except one were '
below background.
R1SBSB01E1, R1SBSB01G1, R1SBSB02I1, R1SBSB06B1, R1SBSB06C1,
R1SBSB06D1, R1SBSB06E1, R1SBSB06F1, R1SBSB06H1, R1SBSB06I1,
R1SBSB07E1
R1-SB-SB09A1-S2, R1SBSB09A1, R1SBSB09D1 •
R1-SB-SB06A1-S2, R1SBSB06A1
R1SBSB02I1
R1SBSB02C1, R1SBSB02I1
R1-SB-SB08A1-S2, R1SBSB02A1, R1SBSB04D1, R1SBSB05A1, R1SBSB05G1,
R1SBSB08A1, R1SBSB08F1
R1SBSB02E1, R1SBSB02I1, R1SBSB05H1, R1SBSB06C1, R1SBSB06G1,
R1SBSB06H1, R1SBSB07B1, R1SBSB07D1, R1SBSB07E1, R1SBSB07I1
R1-SB-SB01C1-S2, R1-SB-SB02D1-S2, R1-SB-SB06A1-S2, R1-SB-SB07H1-S2, R1-
SB17-S2, R1SBSB01C1, R1SBSB01D1, R1SBSB01E1, R1SBSB01F1, R1SBSB01G1,
R1SBSB01H1, R1SBSB02B1, R1SBSB02C1, R1SBSB02D1, R1SBSB02G1,
R1SBSB02H1, R1SBSB02I1, R1SBSB03H1, R1SBSB04C1, R1SBSB06A1,
R1SBSB06B1, R1SBSB06C1, R1SBSB06D1, R1SBSB06E1, R1SBSB06F1,
R1SBSB06G1/R1SBSB06H1, R1SBSB06I1, R1SBSB07B1, R1SBSB07C1,
R1SBSB07D1, R1SBSB07E1, R1SBSB07F1, R1SBSB07I1, R1SBSB08E1.
R1SBSB09E1, R1SBSB09F1, R1SBSB09G1, R1SBSB09I1, R1SBSB1101,
R1SBSB1301, R1SBSB1401, R1SBSB1601, R1SBSB2001, R1SBSB2201
-------
Table 6-5 - page 5
Analyte
Zinc
•
Frequency of
Exceedances
84/106
Range of
Exceed. Cone.
67.5-414
Criteria
Value
67
Background
Cone.
85.06
Units
mg/kg
Sample ID of Criteria Exceedances
R1-SB-SB01C1-S2, R1-SB-SB02D1-S2, R1-SB-SB03B1-S2, R1-SB-SB07H1-S2, R1-
SB.-SB08A1-S2, R1-SB-SB09A1-S2, R1-SBSB04A1-S2, R1-SB-SB06A1-S2, R1-SB-
SB17-S2, R1-SBSB01A1, R1SBSB01B1, R1SBSB01C1, R1SBSB01D1, R1SBSB01E1,
R1SBSB01F1, R1SBSB01G1, R1SBSB01H1, R1SBSB01M, R1SBSB02A1,
R1SBSB02B1, R1SBSB02C1, R1SBSB02D1. R1SBSB02E1, R1SBSB02F1,
R1SBSB02G1, R1SBSB02H1, R1SBSB02I1, R1SBSB03C1, R1SBSB03D1,
R1SBSB03E1, R1SBSBQ3F1, R1SBSB03O1, R1SBSB03H1. R1SBSB04B1,
R1SBSB04C1. R1SBSB04D1, R1SBSB04E1. R1SBSB04F1, R1SBSB04H1,
R1SBSB05A1, R1SBSB05B1, R1SBSB05D1. R1SBSB06A1, R1SBSB06B1,
R1SBSB06C1, R1SBSB06D1. R1SBSB06E1, R1SBSB06F1, R1SBSB06G1, *
R1SBSB06H1, R1SB.SB06I1, R1SBSB07B1. R1SBSB07C1. R1SBSB07D1,
R1SBSB07E1, R1SBSB07F1, R1SBSB07G1, R1SBSB07H1. R1SBSB07I1,
R1SBSB08A1. R1SBSB08C1, R1SBSB08E1, R1SBSB08F1, R1SBSB09A1,
R1SBSB09B1, R1SBSB09C1, R1SBSB09E1, R1SBSB09F1, R1SBSB09G1.
R1SBSB09I1, R1SBSB1101, R1SBSB1201. R1SBSB1301, R1SBS81401,
R1SBSB1501, R1SBSB1601, R1SBSB1701, RISBSB1901. R1SBSB2001,
R1SBSB2101. R1SBSB2201, R1SBSB2301. R1SBSB2401, R1SBSB2501
Subsurface soil
2-Methylnaphthalsne
Acenaphthylene
Acenaphthene
bis(2-Ethylhexyl)phthalate
Fluorene
Naphthalene
13/20
1/20
7/20
1/20
6/20
6/20
34-72000
10000
1100-42900
10100
1200-46500
4000-85300
2.6
1100
1100
6500
1100
3900
N/A
N/A
N/A
N/A
N/A
N/A
ng/kg
Hg/kg
ng/kg
Hg/kg
Hg/kg
fig/kg
R1-SB-SB04A2-S2, R1-SB-SB06A2-S2, R1SBSB03A2, R1SBSB03A3, R1SBSB03A4.
R1SBSB04A2, R1SBSB04A3. R1SBSB06A2. R1SBSB06A3. R1SBSB06A4.
R1SBSB03A2, R1SB3B09A3, R1SBSB09A4
R1-SB-SB06A2-S2
R1-SB-SB06A2-S2, R1SBSB03A2. R1SBSB03A3, R1SBSB03A4, R1SBSB06A2.
R1SBSB06A3, R1SBSB06A4
R1-SB-SB06A2-S2
R1-SB-SB06A2-S2, R1SBSB03A3. R1SBSB03A4. R1SBSB06A2. R1SBSB06A3,
R1SBSB06A4
R1SB-SB06A2-S2. R1SBSB03A3. R1SBSB03A4. R1SBSB06A2, R1SBSB06A3,
R1SBSB06A4
-------
Table 6-5 page 6
Analyte
Phenanthrene
Aroclor-1242
Aroclor-1260
Aluminum
Arsenic
Chromium
Vanadium
Zinc
Frequency ol
Exceed ances
4/20
8/19
1/20
20/20
3/17
3/20
5/20
13/20
Range of
Exceed. Cone.
41000-120000
180-1100
200
11900 23100
31-32.4
109-150
61.7-78.7
68.3-150
Criteria
Value
20000
170
170
50
30
100
60
67
Background
Cone.
N/A
N/A
N/A
32,581
7.30
48.15
N/A
85.06
Units
ng/kg
W/kg
ng/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Sample ID of Criteria Exceedances
R1-SB-SB06A2-S2, R1SBS806A2, R1SBSB06A3, R1SBSB06A4
R1SBSB05A2, R1SBSB05A3, R1SBSB05A4, R1SBSB06A2, R1SBSB06A3,
R1S8SB06A4, R1SBSB09A3, R1SBSB09A4
R1SBSB06A4
All sample locations exceeded criteria value. Howevor, all locations were below
background.
R1SBSB06A2, R1SBSB06A3, R1SBSB06A4
R1-SB-SB06A2-S2, R1SBSB06A2, SBSB06A3
R1-SB-SB04A2-S2, R1-SB-SB06A2-S2, R1SBSB05A4, R1SBSB06A2, R1SBSB06A4
R1-SB-SB04A2-S2, R1-SB-SB06A2-S2, R1SBSB04A2, R1SBSB05A2, R1SBSB05A3,
R1SBSB05A4, R1SBSB06A2, R1SBSB06A3, R1SBSB06A4, R1SBSB07A4
R1SBSB09A2, R1SBSB09A3, R1SBSB09A4
-------
Table 6-5 - page 7
Analyte
Frequency of
Exceedances
Range of
Exceed. Cone.
Criteria
Value
Background
Cone.
Units
Sample ID of Criteria Exceedances
Surface Water
Lead
1/20
0.011
0.0085
N/A
mg/kg
R1SWSG37
Surface Sediment
4-Methylphenol
Fluoranthene
Phenol
Arsenic
Chromium
Nickel
6/52
1/52
10/52
1/52
1/52
1/52
730-3000
4700
440-1400
94.4
300
381
670
2500
420
57
260
140
N/A
N/A
N/A
N/A
N/A
N/A
M-9/kg
ng/kg
ra/kg
mg/kg
mg/kg
mg/kg
R1-SD-SG10-S2, R1-SD-SG32-S2, R2SDSG05, R1SDSG11, R1SDSG20, R1SDSG21
R1SDSG13
R1SDSG01. R1SDSG06, R1SDSG09, R1SDSG10, R1SDSG11. R1SDSG14,
R1SDSG15, R1SDSG16, R1SDSG17, R1SDSG18 '
R1SDSG19
R1SD-SG08-S2
R1-SD-SG08-S2
Subsurface Sediment
Fluoranthene
Pyrane
Arsenic
2720
1/20
1/20
3300-8100
4100
60.9
2500
3300
57
N/A
N/A
N/A
H9/kg
Mg%
mg/kg
R1SDSG2802, R1SDSG2804
R1SDSG2802
R1SDSG1902
-------
Table 9-1
t
Respondents
Cost
Estimate2
$13 .3
$11.8
$18 .6
$22.4
$27.1
$25.6
$36.0
Cost Estimate
(in millions
EPA
Cost
Estimate
<*'i n
-------
Table 10-1
Cost Estimate for Alternative 4c
Geosynthetic Cover with Passive Drainage
Item
Capibtl Costs
Deed modification
Monitoring plan
Well abandonment
Transportation improvement
Clearing and grubbing
Passive Gradine Plan:
Regrade onsite soil
Re-grade waste
Import soil
Surface Water Controls:
Perimeter road/drainase ditch
Perimeter sumps
Wetlands Mitigation
Cover:
Gas system
Establish vegetation
Vegetative layer (import soil)
Edged rain
Geotextile
Flexible membrane liner (FML)
Subtotal Capital Costs
Contractor overhead and profit
Engineering •—
Construction surveillance
Contingency
Total Capital Costs
Operation and Maintenance (O&M) Costs
Cover maintenance
Surface water controls maintenance
Annual groundwater monitoring costs
Subtotal O&M Costs
Contingency
Annual O&M Costs
Net Present Value of O&M Costs
Net Present Value of O&M Costs
Total Alternative Cost (Net Present Value)
Total Alternative Cost (Net Present Value)
Qty
147
300,000
140,000
400,000
12,000
20
1.1
11,000
147
237,000
130,000
6.400,000
6.400,000
.
30
30
Units
LS
LS
LS
LS
acre
cy
cy
cy
ft
sump
acre
ft
acre
cy
ft
sf
sf
•—•
y
y
y
y
y
Unit
Cost
$3,500
$2.00
$3.00
$10.00
$25.00
$6,000
$10,000
$5.00
$1,500
$12.00
$5.00
$0.15
$0.40
10%
8%
3%
25%
25%
$168,000
$168,000
Cost"
55,000
550.000
$30,000
5250.000
$514.000
$600,000
$420.000
$4,000.000
$300,000
$120.000
511,500
555.000
$220,200
$2.844,000
$650.000
$960,000
$2.560.000
$13.539,700
$1,359,000
$1.037,000
$4oT,000
$3,397,000
$19,841.000
$72,000
$12,000
$50,000
$134.000
$34.000
$168,000
$3,763,000
$2.583,000
$23,604,000
$22,424,000
Notes
2,500 fr per outfall
1 ft thick
Net discount rate = 2%
Net discount rate = 5 %
Net discount rate = 1 %
Net discount rate = 5 %
Costs are for mid-1994.- Some costs are rounded.
The sum of capital costs and the net present value of operations and maintenance costs.
-------
Table 11-1-Chemical-Specific ARARs for Surface Water at the Tulalip Landfill Site1
Analyte
Concentration
(mg/L)
Criteria
Reference2'3'4
VOCs
1,1-Dichloroethane
Benzene
Chlorobcnzcne
Chloroform
Chloromethane
Ethylbenzene
VIethylene Chloride
Toluene
rrichloroethene
0.0032
0.071
0.129
0.47
6.4
0.43
1.6
5
0.081
HH - Federal Fish Consumption
HH - Federal Fish Consumption
Eco - Marine AWQC chronic
HH - Federal Fish Consumption
Eco - Marine AWQC chronic
Eco - Marine AWQC acute
HH - Federal Fish Consumption
Eco - Marine AWQC chronic
HH - Federal Fish Consumption
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
BNAs
1 ,2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
2-Methylnaphthalene
2,4-Dichlorophenol
3,3'-Dichlorobenzidine
Acenaphthylene
Acenapthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
8enzo(b)fluoranthene
3 enzo(g ,h 4)perylene
Benzo(k)fluoranthene
bis(2-Chloroethyl)ether
bis(2-Ethylhexyl)phthalate
Chrysene
3i-n-butylphthalate
3ibenz(a,h)anthracene
Diethylphthalate
Tluoranthene
i^luorene
n-Nitrosdipheny lam ine
Naphthalene
5entachlorophenol
^henanthrene
3henol
^yrene
1.97
1.97
1.97
0.3
0.79
0.000077
0.3
0.71
0.3
0.000031
0.000031
0.000031
0.3
0.000031
0.0014
0.0059
0.000031
12
0.000031
120
0.016
0.3
0.016
2.35
0.0079
0.0046
5.8
0.3
Eco - Marine AWQC acute
Eco - Marine AWQC acute
Eco - Marine AWQC acute
Eco - Marine AWQC acute
HH - Federal Fish Consumption
HH - Federal Fish Consumption
Eco - Marine AWQC acute
Eco - Marine AWQC chronic
Eco - Marine AWQC acute
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
Eco - Marine AWQC acute
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
Eco - Marine AWQC chronic
Eco - Marine AWQC acute
HH - Federal Fish Consumption
Eco - Marine AWQC acute
Eco - WA State Marine chronic
Eco - Marine AWQC chronic
Eco - Marine AWQC acute
Eco - Marine AWQC acute
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 13 1,1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
WAC 173-201A
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992; 1995
PCBs/Pesticides
4,4'-DDD
4,4'-DDE
4,4'-DDT
Aldrin
alpha-BHC
Aroclor-1016
Aroclor-1232
Aroclor-1242
Aroclor-1248
Aroclor-1254
ArocIor-1260
0.00000084
0.00000059
0.00000059
0.00000014
0.000013
0.000000045
0.000000045
0.000000045
0.000000045
0.000000045
0.000000045
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
40 CFR Part 131, 1992
40 CFR Part 13 1,1 992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 13 1,1 992
40 CFR Part 131, 1992
-------
Table 11-1-Page 21
Analyte
beta-BHC
Chlordane
delta-BHC
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin
Endrin aldehyde
gamma-BHC (Lindane)
Heptachlor
Heptachlor epoxide
Methoxychlor
Concentration
(mg/L)
0.000046
0.00000059
0.00034
0.00000014
0.0000087
0.0000087
0.002
0.0000023
0.00081
0.000063
0.00000021
0.00000011
0.00003
Criteria
HH - Federal Fish Consumption
HH - Federal Fish Consumption
Eco - Marine AWQC acute
HH - Federal Fish Consumption
Eco - WA State Marine chronic
Eco - WA State Marine chronic
HH - Federal Fish Consumption
Eco - WA State Marine chronic
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
HH - Federal Fish Consumption
Eco - Marine AWQC chronic
Reference213'4
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
WAC 173-201 A
WAC 173-201A
40 CFR Part 131, 1992
WAC 173-201A
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992
40 CFR Part 131, 1992; 1995
INORGANICS5
Antimony
Arsenic
Cadmium
Chromium (VI)
Copper
Cyanide
Lead
Mercury
Nickel
Selenium
Silver
rhallium
Zinc
0.5
0.00014
0.0093
0.05
2.40E-03/2.90E-03
0.001
0.0056/0.0085
0.000025
0.0079/8 .30E-03
0.071
0.0023
0.0065
0.076/0.086
Eco - Marine AWQC chronic
HH - Federal Fish Consumption
Eco - WA State Marine chronic
Eco - WA State Marine chronic
Eco - Mar. AWQC chronic/WA State Mar. acute
Eco - WA State Marine acute
Eco - Marine AWQC chronic
Eco - WA State Marine chronic
Eco - WA State Marine chronic
Eco - WA State Marine chronic
Eco - WA State Marine acute
HH - Federal Fish Consumption
Eco - WA State Marine chronic
40 CFR Part 131, 1992; 1995
40 CFR Part 131, 1992
WAC 173-201 A
WAC 173-201A
l~40 CFR Part 131, 1995/WAC 173-201A
WAC 173-201A
40 CFR Part 131, 1992; 1995
WAC 173-201 A
WAC 173-201A
WAC 173-201 A
WAC 173-201A
40 CFR Part 131, 1992
WAC 173-201A
CONVENTIONALS
Ammonia
0.035
Eco-WA State Marine chronic
WAC 173-201A
'During detailed design, EPA may select a subset of the surface water ARARs for the purpose of monitoring the interim remedy. EPA plans to adjust
compliance levels for these surface water ARARS, if appropriate, to account for practical quantitation limits (PQl/s) and for surface water background concentrations.
1 Values taken from EPA Water Quality Standards 40 CFR Part 131, December, 1992 for the protection of human health from ingestion of seafood. The National Toxics Rule
allows these FederaJ criteria to be used as state standards.
3 Values taken from EPA Water Quality Standards 40 CFR Part 131, December, 1992 and EPA Interim Final Standards, 1995 for the protection of aquatic organisms.
4 Values iWcen from the Washington State WAC 173-201A for the protection of aquatic life.
5 AWQC criteria for inorganics are the same for dissolved or total metals except where a slash indicated otherwise. In this case the first value is the dissolved criteria value.
Translation from total to dissolved metals based on WAC 173-201A calculations.
6 Assume conversion factor of 1.2 from ammonia-N to total ammonia and 5% of total ammonia is un-ionized ammonia.
All AWQC calculations are based on a pH of 7.8 and a hardness of 100 ppm of CaCQj, which is reasonable because these are within ranges that have been measured at the site.
-------
1/2
MILE
PROJECT
LOCATION
VICINITY WAP
NOT TO SCALC
Figure 1-1 SITE LOCATION MAP
-------
Tulolip Landfill
Marysville, Washington
Figure 1-2
-------
MW-20-
2.0
10
ZONE 1 MONITORING WELLS (MW)
ZONE 2 MONITORING WELLS (MW).
PUMPING WELLS (PW). OR PIEZOMETERS (PZ)
REFUSE THICKNESS IN FEET
APPROXIMATE LANDFILL BOUNDARY
REFUSE THICKNESS CONTOUR
BARGE CANAL LOCATION
SCALE IN FEET
SOURCE: U.S. ARMY CORPS OF ENGINEERS. U.S. ENVIRONMENIAL PROTECTION AGENCY.
DATE OF MAP PREPARATION: 11/92.
Refuse Thickness Map
Tulolip Landfill
Marysville. Washington
Figure 5-1
-------
POORLY
GRADED
IISANDll
WITH SILT
LEAN CL
D
SHELL FRAGMENTS
SILTY SAND
///yKtf///
SHELL FRAGMENTS
SILTY SAND
/ /WIJH //
SHELL FRAGMENTS
SILT WITH
SAND AND
SANDY SILT
POORLY GRADED
Sou
Old Barge Canal
LEGEND
NOTES:
SUBSURFACE CONDITIONS BENEATH EBEY AND STEAMBOAT SLOUGHS ARE EXTRAPOLATED FROM DEPARTMENT
OF TRANSPORTATION BORINGS.
THE LINES DESIGNATING THE INTERFACE BETWEEN SOiL AND ROCK MATERIALS ON THE SUBSURFACE PROFILES ARE DETERMINED BY
INTERPOLATION AND ARE THEREFORE APPROXIMATIONS. THE TRANSITION BETWEEN THE MATERIALS MAY BE ABRUPT OR GRADUAL
THE PROFILES SHOULD BE CONSIDERED AS REASONABLY ACCURATE ONLY AT THE BORING LOCATIONS. AND THEN ONLY TO THE
DEGREE IMPLIED BY THE NOTES ON THE BORING LOGS.
COVER (MATERIAL CONSISTS PRIMARILY OF SILT
WITH VARIABLE PERCENTAGE Of SANO)
ZONE 1 (LANDFILL REFUSE)
SILT/CLAY LAYER
(UflTRtAL CONSISTS Of CLAY. SHT. AND SANOY SILT)
CTOUNDWATER ZONE 2
(MATERIAL CONSISTS OF POORLY GRADED SANO AND SILTY SAND)
DEEPER ZONES
(MATERIAL CONSISTS OF SILTY SANO. POORLY GRADED SANO.
AND SILT LAYERS WITH SHELL FRAGMENTS)
52.
CONTACT BETWEEN MAJOR UNITS
CONTACT BETWEEN MATERIAL WITHIN MA,
WELL SCREEN INTERVAL AND
STATIC CROUNOWATER ELEVATION (FEBRI
SCALE: HORIZONTAL 1" " <
VERTICAL EXAGGERATION K 20
Generalized Geologic
NorthiSouth Cross Section
1
Tulolip Landfill
Marysvtile. Washington
5-9-'-
Fie
-------
INFILTRATION
- ZONE 1 WATER LEVEL
ZONE 2 WATER LEVEL
CROUNDWATER
DISCHARGED TO
SLOUGH
DEEPER ZONES
POTENTIAL FOR SLIGHT
UPWARD GRADIENT DUE
TO DISCHARGE TO SLOUGH
Conceptual HydroLogic Model
For Tulalip Landfill
Tulalip Landfill
Marysville. Washington .
Figure 5-3
-------
LEGEND
flj MONITORING WELL
2.53 GROUNDWATER ELEVATION, NGVD
APPROXIMATE LANDFILL BOUNDARY
„ CL_ POTENTIOMETRIC SURFACE
2' ELEVATION CONTOUR
BARGE CANAL LOCATION
I
1600
SOURCE: HLA, 1995. TOPOGRAPHY FROM MAP TITLED "TULALIP
LANDFILL, MARYSVILLE WA", DRAWN BY U.S. ARMY CORPS OF
ENGINEERS, U.S. ENVIRONMENTAL PROTECTION AGENCY.
DATE OF MAP PREPARATION: NOVEMBER, 1992.
Figure 5-4
AVERAGE ZONE 2
POTENTIOMETRIC SURFACE
DURING 72-HOUR TIDAL STUDY
-------
m
m
i
1
1
1
1
1
1
1
1
1
I
H
•
Primary
Source
WASTE
Primary Secondary
Release Source
Mechanism
f Direct ^\
V Contact J Soil
"-- — -" 1 1
(
— QLeachingJ)— Groundwater
Zone 2
r— Surface — —
/^~~ ~"--\ Water
f Erosion / V—
~V^ Runoff J
Secondary
Release
Mechanism
Runoff / J
\ ^~^
(^0^^}
i I
( Resuspension 7\
\^^ Deposition^^y
Exposure
Medium
On-Source
Soil
Off-Source
Soil
Leachate
On-Source
Surface Water
Off-Source
Surface Water
Off-Source
Sediment
Vapors
-c
rC
*
>
1 >
— *»
Exposure Receptor
Pathway
Ingestion
Ingestion
Dermal Contact
Ingestion of
Fish/Shellfish
Contacting Leachale
Ingestion
Dermal Contact
Ingestion
Dermal Contact
Ingestion of
Rsh/SheUfish
in Surface Water
Ingestion
Dermal Contact
Ingestion of
Fish/Shellfish
contacting sediment
Inhalation
Industrial / Commercial
Uterv ((uture)
•
•
D
O
0
o
o
Q
O
•
u
0
o
c -2
O
©
®
•
0
o
u
0
0
0
0
o
Child Recreational
User (current/future)
o
@
®
9
O
o
o
0
O
0
0
0
o
EXPLANATION
(~^) Not considered a viable pathway 1 UlcUlp LclD
• Pathway evaluated in streamlined baseline Risk Assessment, HUHian Health COnC6ptUal SJt6 MC
(jj^ Pathway to be evaluated in off-source comprehensive baseline risk assessment
H Pathway evaluated in streamlined Risk Assessment and in upcoming of f -source comprehensive baseline risk assessment Pioure 5
I I Pathway not evaluated due to lack of available comparison numbers ' - . f^ ,JC?
-------
Primary
Source
WASTE
Primary
Release
Mechanism
f Direct >,__
*v Contact )
— ( Leaching J
( Erosion / ^
'v Runoff J
Secondary
Source
Zone 1 &
Zone 2
Surface
Water
Sediment
Secondary
Release
Mechanism
>
/"Eros
( Run
V__Leac
*1
>
r
ion/~\
off/ )
hing_^^
^--
( Groun
ls. Discr
' i
i
/Resusp
V Depc
'
Jwa
iarg
— ^
ter >,
<*S
ension 7\
sition ^/
r
Exposure
Medium
On-Source
Soil
Off-Source
Soil
Leachate
On-Source
Surface Water
Off-Source
Surface Water
Off-Source
Sediment
—
— -
£Z« 1 ll**i"wrfc — ~ 1
|
a
c
1
rm.-nri.l
PUnli
Bud.
MiRinuli
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lnvcr«b™lc»
BinJ.
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:
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Blrdi
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BInJi
o
0
o
o
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Q
— >•
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o -
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\
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^
O
o
U
0
o
0
0
0
O
O
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n
o
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Q
U
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u
r~
1
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0
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u
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EXPLANATION
(_) Not considered a viable pathway
^P Pathway evaluated in streamlined baseline Risk Assessment
<{jj) Pathway to be evaluated in off-source comprehensive baseline risk assessment
ll Pathway evaluated in streamlined Risk Assessment and in upcoming off-source comprehensive baseline risk assessment
I | Pathway not evaluated due to lack of available comparison numbers
Tulalip Landfill
Ecological Conceptual Site Model
Figure 5-6
-------
LStO
4,4' - DOT
Aldrin
Arodor-1016
Arodor-1232
Arsenic (di*sotved)
Heptachlor
Heptachlor epoxide
E 8 E Y
ISLAND
LS03
4, 4' - DDT
Atdrin
Arodor-1232
Arsenic {total)
Arsenic (dissolved)
Dieldrin
Heptachlor epoxtde
LS06
4, 4' - ODD
4, 4' - DDE
4, 4' - DDT
Atdrin
Aroclor-1016
Arsenic (total)
Arsenic (dissolved)
Benz(a)anthracen e
Benzofa)pyrene
Benzo(b)fluoranthen«
Benzo
-------
GWMW10
On-Source Groundwater Zone 2
Nickel
LS10
Off-Source Leachate
4, 41 DOT
Aroclor 1016
Aroclor 1232
Heptachlor epoxide
LS09
Off-Source Surface Soil
Afoclor 1242
LS08
Off-Source Surface Soil
2-Methylnaphttia1ene
4,4'DOT
Off-Source Subsurface Soil
2-Methylnaphthalene
Off-Source Leachate
4, 4' DDT
Aroclor 1232
Cyanide
Off-Source Leachate
4,4' DDT
Aldrin
Aroclor 1016
Aroclor 1232
Aroclor 1254
Copper
Cyanide
Endrin
Lead
Mercury
Zinc
LS11
Off-Source Surface Soil
2-Melhylnaphtrialene
Off-Source Leachate
Aldrin
Aroclor 1016
Copper
Cyanide
Nickel
GWMW21
On-Source Groundwater Zone 1
Cyanide
Lead
Zinc
GWMW13
On-Source Groundwater Zone 2
Cyanide
GWTB01
On-Source Groundwater Zone 2
Cyanide
On-Source Surface Water
Copper
Lead
LS02
Off-Source Surface Soil
2-Methyinaphthalene
GWTB10
On-Source Groundwater Zone 1
Copper
Cyanide
1 Lead
Off-Source Leachate
4, f DDT
Aroclor 1016
Copper
Cyanide
Lead
Zinc
GWMW07
On-Source Groundwater Zone 2
Nickel
LS06
Off-Source Surface Soil
Acenaphttiene
Naphthalene
LS03
Off-Source Leachate
4,41 DDT
Aroclor 1232
Copper
Cyanide
Endrin
Lead
Heptachlor epoxide
Off-Source Subsurface Soil
Acenaphthene
Ruorene
Naphtha!
GWMW23
On-Source Groundwater Zone 1
Heptachlor epoxide
LS04
Off-Source Surface Soil
2-MeUiylnaphttialene
Off-Source Leachate
4,4'DDT
Aroclor 1016
Copper
Cyanide
Dieldrin
Endrin
Heptachlor epoxide
Lead
Mercury
Nickel
Phenanthrene
LSOS
Off-Source Leachate
4, 4' DDT
Aroclor 1016
Aroclor 1232
Copper
Cyanide
Endrin
Heptachlor epoxide
Lead
Off-Source Subsurface Soil
2-Methylnaphthalene
GWTB06
On-Source Groundwater Zone 2
Cyanide
Off-Source Leachate
Aroclor 1016
Lead
EXPLANATION
Off-Source Leachate Seep Sample Location with Media and Contaminant listed
V Off-Source Surface Water Sample Location
On-Source Groundwater Sample Location with Media and Contaminant listed
Note: Ammonia-Nitrogen exceeded criteria in all leachate. Zone 1 groundwater, and Zone 2 groundwater samples
Figure 6-2
Exceedances of Ecological
Comparison Numbers Greater than
1 Order of Magnitude
On-Source Surface Water Sample Location
On-Source Leachato Seep Location
-------
Passive Vent*
Gas System
Probable Cost
$2,708,075
' P = 0.40
($1,422,540)
Active Collection*
P = 0.60
($3,565,099)
Table 4A
Horizontal Collection
(Trench)
P = 0.05
($5,113,731)
Vertical Wells
P = 0.05
($4,760,088)
Surface Collection
P = 0.90
($3,412,676)
* Probability Based on Nuisance Odor
Note: Dollar amounts shown have not been multiplied by the corresponding probability.
Open Flare
P = 0.25
Enclosed Flare
P = 0.75
Open Flare
P = 0.25
Enclosed Flare
P = 0.75
Open Flare
P = 0.25
Enclosed Flare
P = 0.75
Table 4B
($4,985,845)
Table 4C
($5,156,360)
Table 4D
($4,560,145)
Table 4E
($4,826,735)
Table 4F
($4,795,620)
Table 4G
($2,951,695)
Decision Tree and Most Probable Cost
for Landfill Gas System
Figure 10-1
Note: For more information regarding this Figure, see interim ROD Appendix B.
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Interim Remedial Action ROD
APPENDIX A
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Appendix A:
Summary of Comparison of
Remedial Alternatives 2b, 2b(ii), 3, 4a, and 4b in
Relation to the NCP Balancing Criteria
The following alternatives do not meet the two National
Contingency.Plan (NCP) "threshold criteria":1
2b Leachate Collection with Discharge to Treatment Berm
2b(ii) Leachate Collection with Discharge to POTW2
3 Leachate Seep and Ground Water Collection and Treatment
4a Soil Cover with Passive Drainage
4b Geosynthetic Cover with Active Drainage
Because these alternatives do not meet the two'threshold
criteria, they were not carried further through the comparative
analysis in the ROD. However, this appendix provides a
comparative analysis of these alternatives to the NCP criteria 3
through 7:
3. Long-term effectiveness and permanence considers the ability
of an alternative to maintain protection of human health and the
environment over time, and the reliability of such protection.
Alternative 4a - Soil Cover with Passive Drainage, would be
relatively permanent in the long term. But, because it would not
meet many of the RAOs, including eliminating Zone 1 leachate
discharges through the berm, and minimizing contaminated Zone 2
ground water to the sloughs, it is not considered to be an
effective alternative in the long term.
-_The Geosynthetic Cover with Active JDrainage (4b) partially
meets this criterion. Because this alternative would rely
heavily on an external power source over the long term, EPA
considers it to be less permanent because of the increased
potential for system failure, and because the future cost of
operating the system would increase if future energy costs rise.
Because there is considerable uncertainty regarding the
potential effectiveness of the following alternatives, EPA
considers them to be ineffective in the long term:
1 The two threshold NCP Criteria are: 1. Overall Protection of Human
Health and the Environment; and 2. Compliance with Applicable or Relevant and
Appropriate Requirements (ARARs). Section 9.0 of the ROD explains why these
alternatives do not meet the threshold criteria.
2 Publicly Owned Treatment Works
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2b Leachate Collection with Treatment Berm
2b(ii) Leachate Collection with Discharge to POTW
3 Seep and Zone 2 Ground Water Controls
EPA has serious concerns about the long-term effectiveness
of the Leachate Collection with Treatment Berm alternative (2b)
as proposed for this Site. The adequacy and reliability of a
treatment berrn concept at a site like the Tulalip Landfill is
highly uncertain. A containment berm project that has been
implemented at the Port of Seattle's Terminal 91 has been
suggested by the Respondents as a successful precedent for
installing a treatment berm system at Tulalip. However, EPA's
review of the Terminal 91 project indicates that the Terminal 91
project is not analogous to the berm system proposed for Tulalip
Landfill, and is not a good predictor or indicator of success for
treatment at Tulalip Landfill. For example, the Terminal 91 berm
was designed to immobilize and contain PAHs and PCBs. This is a
fundamentally different objective than treating, chemically
degrading, and dispersing wastes, as proposed at the Tulalip
Site. Chemically, the waste materials very different, and the
flux rates and systems to move water are much more complex at the
Tulalip Site.3 The ability of the proposed treatment berm
system at Tulalip Landfill to treat most or all of the
contaminants of potential concern at both Terminal 91 and the
Tulalip Landfill remains undocumented. The Respondents have
acknowledged that "the effectiveness of the treatment berms under
these (i.e., Tulalip) site conditions for this leachate cannot be
confirmed until after implementation."4 In other words, the
only way to really know if the system would work is to build it
and then attempt to evaluate whether it is effective.
Based on EPA's evaluation of technical information regarding
the Terminal 91 project, EPA finds no basis to conclude that
contaminant concentrations were reduced within the Terminal 91
berm by any means other than dilution (ie., mixing of
contaminated ground water with "clean" surface water within the
berm). Further, no information has been presented to EPA showing
that such a berm treatment system has ever been implemented at a
landfill site, so its effectiveness at a Site like Tulalip
landfill is unknown. If either the collection system or the berm
proposed for Alternative 2b turns out to be ineffective,
significant damage to the environment could result, and
subsequent implementation of effective contingent measures (such
See Memorandum by Eric Winiecki to The File, August 4, 1995,
regarding EPA Review of Alternative 2b - Treatment Berm (see especially
attached memoranda by Glenn Bruck and Rene Fuentes) in the Administrative
Record for this interim ROD.
4 See Memorandum by Eric Winiecki to The File, August 4, page 2.
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as a landfill cover and other identified measures) would
significantly increase the costs of the containment remedy.
EPA also has concerns regarding the long-term effectiveness
of the basic leachate collection system concept proposed for the
Treatment Berm alternative (2b) and the Discharge to POTW
[2b/ii)J alternative. No information has been provided to EPA
that shows such a collection system, requiring thousands of feet
of drainage trenches constructed within landfill waste, has ever
been implemented at any site. EPA believes there is a high risk
of these collection systems clogging in the long term as a result
of accumulation in the collection system of chemical
precipitates, microorganism growths, or settlement of
particulates, which could result in high operation and
maintenance (O&M) costs to address the problems, or a future need
to install a more effective remedy, such as a low permeability
landfill cover. The gradients proposed for the collection
trenches would provide little tolerance for errors in the
placement and elevation of the pipes in the interceptor trenches.
Such precision could be difficult to achieve considering the
potentially variable nature of the substrate (silts, sands, clays
and waste materials) on which the pipe would be laid. The
potential for differential settlement of wastes and sediment
would be difficult to predict. The installation of the trenches
also calls for the addition of approximately 20 feet of materials
over the pipes. This additional load would increase the
potential for pipe settlement and gradient changes after the pipe
has been laid. Such changes may result in flow stagnation and
ineffective drainage.5
The occurrence of any or all of these problems would mean
that the carefully modeled flows and infiltration rates would be
changed. The probable result would be increased infiltration
down into Zone two (and possibly to the perimeter berm leachate
seeps) and less water flowing through the collection system.
Because of the relatively high potential for collection
system ineffectiveness or failure, EPA considers Alternatives 2b
and 2b(ii) to be impermanent relative to alternatives that employ
proven landfill containment technologies such as low permeability
covers. Alternative 2b(ii) is also considered to be impermanent
because of its.relatively high O&M costs.6 In addition, because
most of the predicted O&M costs associated with 2b(ii) are for
POTW treatment, the future viability of this alternative would be
vulnerable to any unforeseen increases in the price of POTW
5 See Memorandum by Eric Winiecki to The File, August 4, page 2. See
especially attached memorandum by Glenn Bruck.
6 EPA's O&M cost estimate for Alternative 2b(ii) is $465,000 per year;
the Respondents' estimate is $386,000 per year.
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treatment. This system would also be vulnerable to any future
increases in the cost of power to run the collection system
pumps.
The Seep and Zone 2 Ground Water Controls alternative (3)
may not effective in the long term. Because Site investigations
have found that there is no consistent aquitard in which a slurry
wall could be effectively anchored in Zone 2, the ability of this
alternative to effectively ensure the collection of leachate and
ground water is uncertain. This is an active system with a
relatively high reliance on an outside power source, and it is
considered to be relatively impermanent because of its relatively
high O&M costs.7
4. Reduction of Toxicitv, mobility, or volume through treatment
evaluated an alternatives's use of treatment to reduce the
harmful effects of principal contaminants, their ability to move
in the environment, and the amount of residual contamination
remaining.
Alternative 3 - Leachate Seep and Ground Water Collection
and Treatment, and Alternative 2b(ii) - Leachate Collection with
Discharge to POTW, are expected to meet this criterion because
leachate would be pumped to a POTW for treatment. However,
information has not been provided to EPA that shows that the POTW
treatment systems are capable of effectively treating all of the
contaminants of concern in the leachate.
Alternatives that do not meet this criterion are:
2b Leachate Collection with Treatment Berm
4a Soil Cover with Passive Drainage
4b Geosynthetic Cover with Active Drainage
The Leachate Collection with Treatment Berm alternative (2b) is
considered not to meet this criterion because its ability to
treat contaminants is uncertain. In addition, the potential for
significant clogging of the Treatment Berm could result in the
release of untreated contaminants. Paradoxically, if the
treatment berms turn out to be ineffective at treating the
leachate, and the collection system has the effect of mobilizing
contaminants that otherwise would have remained in place, this
alternative could result in greater amounts of contaminants
discharging to the environment than current levels. Alternatives
4a and 4b are alternatives that are generally consistent with the
presumptive remedy approach of containment; they would not
employ any form of treatment.
7 The O&M cost estimate for Alternative 3 is $620,000 per year.
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5. Short-term effectiveness considers how fast the alternative
reaches the cleanup goal and the risks the alternative poses to
workers, residents,,and the environment during construction or
implementation of the alternative.
None of these alternatives (2b, 2b(ii), 3, 4a, and 4b) is
expected to pose risk to the surrounding community during
construction or implementation because the Site is relatively
isolated. Any significant impacts would likely be confined to
the immediate vicinity of the Site.
All of these alternatives would potentially pose some risk
to workers because all involve some excavation of waste.
Excavation in landfills is a relatively common practice, and EPA
anticipates that effective measures would be taken to mitigate
risks. However, alternatives 2b and 2b(ii), which involve
digging trenches through the waste, could pose significant risks
to workers, relative to other-alternatives. The trenches, which
would be 3 feet wide and up to 17 feet deep, would be expected to
partially fill with standing leachate during construction. If it
becomes necessary for workers to enter the trenches during
construction, either to facilitate digging the trenches or
installing the drainage system inside the trenches, there is a
potential for trench cave-ins, and greater worker exposure to
landfill waste, leachate, and gas. Workers would need to wear
appropriate protective gear and work in confined space
conditions, which can be expensive and relatively dangerous. EPA
is unaware of any other Site where similar trenches have been
constructed in landfill waste. Unanticipated safety issues could
arise during construction.
These alternatives would have at least some short-term
adverse impact on the environment during implementation or
construction. For example, if the Leachate Collection with
Treatment Berm alternative (2b) is not effective at treating
leachate, it could worsen environmental conditions by mobilizing
additional leachate and releasing it to the environment.
Alternatives 2b and 2b(ii) would unearth large quantities of
waste which would not be treated or contained under a low
permeability cover. The capping alternatives 4a and 4b would
require importing fill material to bring the landfill surface up
to the 2% minimum grades required by the MFS.8 The additional
weight of imported fill on the landfill could cause a short-term
increase in the rate of leachate migration through the perimeter
seeps and down into Zone 2, but potential problems such as this
are typically addressed during detailed design. Because the
Geosynthetic Cover with Active Drainage alternative (4b) would
8 However, the amount of off-site fill that would need to be imported
can be reduced by re-positioning existing landfill materials to achieve the
necessary grades.
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require less excavation and less imported fill material than the
passive cover designs, it may have less short-term adverse impact
on the environment during construction.
Alternatives 3 and 4b would likely achieve the cleanup
objective for eliminating the release of leachate from surface
seeps. Alternative 3 - Seep and Zone 2 Ground Water Controls, is
expected to meet the cleanup goals for the leachate seeps
immediately after implementation. This alternative would utilize
active pumping of leachate, which would result in faster
elimination of the seeps. Alternative 4b - Geosynthetic Cover
with Active Drainage, is predicted to "dry up" the leachate seeps
and meet surface water ARARs at the sloughs__within 2 years of
construction completion. This alternative would cut off
infiltration of rain water through the waste, thus minimizing the
generation of new leachate.
Ground water modeling conducted by the Respondents during
the Remedial Investigation (RI) suggests that Alternative 4a,
Soil Cover with Passive Drainage, would not reduce infiltration
enough"to eliminate the perimeter seeps.
It is uncertain whether alternatives 2b - Leachate
Collection with Treatment Berm, and 2b(ii) - Leachate Collection
with Discharge to POTW, would be effective in lowering the
leachate mound enough to result in the elimination of the Zone 1
perimeter seeps. EPA has additional concerns about the Treatment
Berm concept proposed for Alternative 2b because such a system
has never been implemented at a site like Tulalip Landfill, and
its effectiveness is uncertain. It is possible that actual
"treatment" within the berm may never occur. Until conditions
within the berms developed that would enable treatment to occur
(if ever), this alternative would permit the release of
significant quantities of contaminated leachate into the surface
waters after passing it, untreated, through the berms.
EPA has received no information which shows that the
leachate collection system concept proposed for Alternatives 2b
and 2b(ii) has ever been implemented at a Site like the Tulalip
Landfill. The Respondents who submitted these alternatives claim
that they would be immediately effective in stopping the leachate
seeps. However, because of potential delays associated with the
administrative and technical obstacles associated with these
alternatives (see discussion of NCP criterion number 6 -
Implementability), their short-term effectiveness is considered
uncertain.
6. Implementability considers the technical and administrative
feasibility of implementing the alternative, such as the relative
availability of goods and services. Also, it considers whether
the technology has been used successfully on other similar sites.
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Alternative 4b - Geosynthetic Cover with Active Drainage, is
implementable at the Site. Technically, construction of a
landfill cover is a- common landfill remedy that can be readily
implemented at Tulalip Landfill. In general, materials for these
types of covers are available. The most significant difference
in implementability with the Tulalip Landfill is that it is flat,
so that a mounded cover must be constructed with surface water
runoff controls to minimize infiltration and generation of
leachate. A cover with an active surface water handling design
requires the importation of less fill material than the cover
alternatives that employ "passive" drainage. However, the active
drainage cover does not comply with Washington State Minimum
Functional Standards (MFS), which require minimum 2% surface
slopes of the cover system. This alternative, which involves an
active pumping system to move rainwater off the cover, would
require provision of a power source or power line out to the
landfill.
One aspect of implementability is the ability to monitor the
remedy's effectiveness, and the ease of maintaining the remedy.
Based on EPA's experience at other CERCLA landfills across the
country, geosynthetic covers have a known performance record and
are relatively reliable if properly constructed. It would be
relatively easy to monitor the leachate seeps to evaluate if they
dry up. Water levels in piezometers located on the landfill
could be.monitored to evaluate whether the leachate mound within
the waste is falling, which would indicate that leachate
migration through the deeper ground water is being reduced. An
advantage of a landfill cover is that if an obvious problem
becomes apparent, such as surface water ponding in the case of
the passive cover, it is relatively easy to access and make
repairs to the cover because the cover system is located on the
surface of the landfill. All covers develop leaks, and
installing a leak detection system beneath the cover would not be
practical.
Based on current information, the following alternatives are
considered significantly less implementable:
2b Leachate Collection with Treatment Berm
2b(ii) Leachate Collection with Discharge to POTW
3 Seep and Zone 2 Ground Water Controls
Materials to construct these alternatives should be readily
available. Because the collection systems for^jthe Treatment Berm
alternative (2b), and the Discharge to POTW alternative [2b(ii)];
have never been implemented at a site like the Tulalip Landfill,
some of the possible technical difficulties that may be
encountered during construction are unknown. For example, in
constructing the collection system, it would likely be difficult
to construct trenches 3 feet wide and 17 feet deep through the
landfill waste, which includes large pieces of debris such as
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concrete slabs and wood pilings. It may also prove very
difficult to install level collection pipes in several feet of
standing water, which would be expected to collect in the
trenches during construction. Once constructed, the collection
system or term could develop unforeseen problems that could be
difficult to correct, especially since the system is constructed
largely underground and may be difficult to access to make some
types of required repairs. Although it may be feasible to clean
out the drainage trench pipes if sumps are included in the
design, correcting serious clogging problems that may develop in
the granular drainage material in the trenches could require
excavating and replacing portions of the trench collection
system, which would likely be difficult, costly, and may
interfere with future land use activities.
Because up to 95% dilution of existing contaminants is
expected in the berms proposed for the Treatment Berm alternative
(2b), it would be very expensive or impossible to monitor whether
the berms were achieving significant treatment of the leachate or
mere dilution with the slough water. The Respondents estimate
that 2.8 acres of off-source wetlands would be adversely impacted
or lost in order to construct the proposed treatment berms. The
Respondents propose to establish 4.8 acres of "new" wetlands on
top of the treatment berms. However, EPA believes it is unlikely
that functional wetlands could be maintained on top of the berms
given the likelihood that, due to rapid pore space clogging,
portions of the berms may need to be excavated and replaced on a
regular basis. In EPA's view, the Respondents' proposal would
dredge and fill existing high quality wetlands and replace them
with frequently disturbed, low quality wetlands. Because
construction of the Treatment Berms would require destruction of
about twice the amount of wetlands than would the cover
alternatives (approximately 1.7 acres), administrative difficulty
is anticipated in complying with the requirements of CWA
404(b)(1). CWA 404(b)(1) requires avoidance of wetland
destruction if alternative actions are available, and in this
case, there are other viable remedial alternatives (i.e.,
capping) that are expected to effectively contain the landfill
wastes and would entail destruction of fewer acres of off-source
wetlands.
With regard to the Discharge to POTW alternative [2b(ii)],
delays could result from administrative difficulties with
obtaining permits and access for construction of the proposed
sewer line to the POTW. The Respondents' October 25, 1995,
submittal included a September 28, 1995, letter from Gene Bennett
of the Everett POTW to Mr. Scott Kindred of Colder Associates
which indicated that the POTW saw no technical reason that the
Everett Water Pollution Control Facility could not accept the
discharge of this wastewater at the flow rates proposed by the
Respondents. However, the letter from the Respondents to the
POTW in which the Respondents described the Tulalip Landfill
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leachate and its constituents has not been provided to EPA. Nor
has an analysis which demonstrates to EPA that the Everett POTW
would effectively treat all of the constituents in the Tulalip
Landfill leachate been provided. Access would need to be
obtained to construct the pipe across at least one private
property parcel, and the pipe would also need to cross the
Burlington Northern railroad tracks and a highway. Obtaining
access for the discharge pipe could substantially delay
implementation of this alternative.
The Seep and Zone 2 Ground Water Controls alternative (3) is
considered relatively infeasible because of the difficulty in
constructing a slurry wall down into the Zone 2 aquifer.
Problems such as heaving sands could make construction of such a
slurry wall difficult or impossible.
7. Cost includes estimated capital and operation and
maintenance costs, as well as present worth costs. Present worth
cost is the total cost of an alternative over time in terms of
today's dollars. Cost comparison information for these
alternatives is•provided in Table 9-1 in the interim ROD. The
net present value of each alternative includes capital and O&M
costs, and were calculated assuming a discount rate of 5% over 30
years.
As shown in interim ROD Table 9-1, EPA and the Respondents
have developed different cost estimates for Alternatives 2b -
Leachate Collection with Discharge to Treatment Berm; 2b(ii) -
Leachate Collection with Discharge to POTW; and 4b -
Geosynthetic Cover with Active Drainage. With regard to
Alternative 4b, EPA has added a contingency cost of $2.7 million
to the Respondents' cost estimate from the SAC FS to allow for
the possibility that landfill gas will need to be treated to
comply with Puget Sound Air Pollution Control Authority (PSAPCA)
requirements. In relative terms, EPA's cost estimate for
Alternative 4b ($21.3 million) does not differ substantially from
the Respondents' estimate ($18.6 million). ~
After reviewing and evaluating the Respondents' cost
estimates for Alternatives 2b and 2b(ii), EPA has concluded that
the Respondents incorporated some unrealistic assumptions into
developing these cost estimates. In effect, the Respondents
assumed a "best case" (i.e. extremely low) cost scenario with
regard to Alternatives 2b and 2b(ii) that they did not use in
developing cost estimates for other alternatives. The result is
that their cost estimates for these two alternatives are
inappropriately low. Given the unproven nature of the
technologies employed by Alternatives 2b and 2b(ii), and the
relatively low level of certainty regarding the potential
implementability and effectiveness of these alternatives at the
Site, EPA believes that more realistic, conservative assumptions
should have been used so that the relative costs of these
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alternatives can be properly compared to the estimated costs of
other alternatives in the analysis, as required by the NCP.
Therefore, EPA has independently developed cost estimates for
these two alternatives, using more realistic, conservative
.assumptions.
. For example, with regard to the collection system, which is
similar for both Alternatives 2b and 2b(ii), EPA's cost
assumptions differed from the Respondents' on the following basic
points:
• EPA believes that the Respondents' estimate of the necessary
distance between collection trenches is not sufficiently
conservative. The Respondents assumed the refuse layer to
be more horizontally permeable than it may actually be (more
testing would be needed to more accurately estimate this
permeability), and they concluded that the trenches should
be spaced 400 feet apart. Based on the current degree of
uncertainty regarding the horizontal permeability of the
waste, EPA believes a lower permeability should be assumed,
and EPA has accordingly concluded for the purposes of the
cost estimate that the trenches should be spaced 200 feet
apart. EPA has added four additional sumps for the
additional drainage pipe to accomodate the reduced trench
spacing.
• The Respondents were unclear about what would be done with
some of the excavated waste from the trenches; EPA included
an estimate for off-site disposal of this waste in a solid
waste landfill.
• The Respondents did not appear to have included increased
costs due~ to handling saturated trench spoils; EPA included
costs for hauling and storing the spoils on a stockpile pad
composed of HDPE and sand to prevent further contamination
of the landfill surface.
• To alleviate trench instability during wet excavation, EPA
included costs for the use of a trench box and 40% over-
excavation to lay back trench walls.
• EPA assumed a one-foot topsoil cover over 1/2 the landfill
would be necessary to prevent human exposure to wastes and
contaminated soil (the landfill surface would require
additional chemical characterization to determine the
appropriate extent of such cover material).
Specifically regarding the treatment component of
Alternative 2b, EPA made the following cost assumptions
concerning the proposed treatment berm system:
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• EPA assumed a more conservative cost for sheet pile of $12
per square foot.
• EPA included the cost of increasing the height of the
treatment berms by 5 feet to prevent leachate blowouts at
the berm surface, which EPA believes may occur at the berm
height proposed by the Respondents.
• Potential O&M costs for the treatment berm system is highly
uncertain because of the unproven nature of treatment berms
at a Site like the Tulalip Landfill. Because EPA is very
concerned that the berms could experience significant
problems due to plugging of the pore spaces within the berm
by metal precipitates and biosludges, EPA has incorporated
costs for partial replacement of the treatment berms every
10 years. However, EPA notes that even this increased cost
estimate could seriously underestimate the actual cost of
O&M for the berms if plugging turns out to be a serious
problem after the system is constructed.
Specifically regarding the treatment component of
Alternative 2b(ii), EPA made the following cost assumptions
concerning the proposed discharge to a POTW:
• EPA updated the waste disposal costs for excess trench
spoils to $60 per cubic yard to reflect disposal facility
tipping fees ($42 per cubic yard) as well as loading and
hauling costs ($18 per cubic yard).
• EPA increased the O&M cost for the 24 extraction wells to
allow for monthly inspections and periodic repair and/or
replacement of each pump at an annual cost of $1,250 per
pump.
• Costs for POTW disposal of the leachate were increased based
on current estimates from the POTWs.
In summary, EPA believes that the higher cost estimates EPA
has developed for Alternatives 2b and 2b-(ii) are more accurate
than the cost estimates provided by the Respondents. EPA's cost
estimates account for more of the uncertainty that is inherent in"
the unproven 2b and 2b(ii) alternatives, and allow more realistic
comparison of the costs of these alternatives with the other
alternatives that EPA has evaluated using the NCP criteria in the
interim ROD. For additional information on how and why EPA's
cost assumptions for Alternatives 2b and 2b(ii) differ from the
Respondents', see the interim ROD Appendix E, and also EPA's
August 3, 1995, comment letter on Alternative 2b, which is
available in the administrative record).
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Interim Remedial Action ROD
APPENDIX B
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Appendix B:
Cost Estimate for
Contingent Landfill Gas Treatment System1
Figure 10-1 in the interim ROD depicts a decision tree for
the gas collection and treatment contingent cost estimate. The
costs estimates that were used in the decision tree are shown in
the tables in this appendix. The decision tree in Figure 10-1
identifies seven different contingent solutions. EPA plans to
incorporate one of these contingent solutions into the landfill
cap design if EPA determines that landfill gas control is needed.
The seven cost tables correspond to the seven solutions shown on
the decision tree; a discussion of each follows:
Table 4A assumes a passive vent system. This system includes a 6-inch sand layer
under a geomembrane cap. This layer will act as a bedding layer for the
geomembrane cap and will allow gas to move horizontally under the cap. One vent
per acre will penetrate the cap system. Each vent will have a limited amount of
horizontal perforated pipe traveling horizontally through the sand layer to gather gas.
The O&M costs shown in the table account for inspection of the vents and
replacement if any vent becomes plugged.
Table 4B assumes a horizontal trench system with an open flare. This system includes
a 2- to 3-foot-wide by 6-to 10-foot-deep trench including a perforated pipe running the
length of the trench with periodic standpipes to remove the gas from the trench. The
trenches would run the length of the landfill and be spaced 75 feet apart. A blower is
included to supply a small vacuum to the system, and an open flare is included to bum
the removed gas. The O&M costs account for yearly maintenance, inspection, and one
replacement of the flare and blower over the 30 year period.
Table 4C assumes a horizontal trench system with an enclosed flare. This table is
nearly identical in form and assumptions as Table 4B. The only difference is this
table includes an enclosed flare system which costs slightly more to purchase and
maintain; however, it is more efficient than the open flare system.
Table 4D assumes a vertical well system with an open flare. The system includes
perforated gas extraction wells on a 100- by 100-foot grid system over the entire
landfill. These wells are connected to a blower and open flare via an overland piping
system. The wells are assumed to vary in depth from 10 to 30 feet, on average 20
feet deep. The O&M costs account for yearly maintenance, inspection, and one
replacement of the flare and blower over the 30-year period.
The source of this Appendix is an August 1, 1995, letter from Keith
Pine of Weston, Inc. , to Eric V.'iniecki of EPA. This letter is included in
Section 3.1 of the Administrative Record for the Tulalip Landfill interim
remedial action.
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Table 4E assumes a vertical well system with an enclosed flare. This table is nearly
identical in form and assumptions as Table 4D. The only difference is this table
includes an enclosed flare system.
Table 4F assumes a surface collection system with an open flare. The system includes
a 6-inch sand layer under the geomembrane cap. This layer allows the gas to move
horizontally under the cap. A standpipe will penetrate the liner and connect to a
predetermined amount of perforated horizontal piping within the sand layer. One
stand pipe with horizontal piping will be installed per acre. These standpipes will be
connect to a blower and open flare via an overland piping system. The O&M costs
account for yearly maintenance, inspecrion, and one replacement of the flare and
blower over the 30-year period-
Table 4G assumes a surface collection system with an enclosed flare. This table is
nearly identical in form and assumptions as Table 4F. The only difference is this
table includes an enclosed flare system.
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Table 4A-Landfill Gas Contingency-Passive Vent System
Item
Quantity
Units
Unit Cost
Cost I
Capital Costs
Install Passive Vents
Mobilization/Demobilization
Sand Layer (6" Vent Layer)
Vents (I/Acre)
Subtotal Capital Costs
EPA Oversight
Contractor Overhead and Profit (10%)
Engineering Q5%)
Contingency (25%)
Total Capital Costs
1
120,000
147
LS
CY
L_ EA
$7,500
$6
$500
$7,500
$720,000
$73,500
$801,000
$28,890
$80,100
$120,150
$200,250
$1,230,390
Operation & Maintenance (O&M) Costs
Vent Maintenance
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%)
1/yr
LSn
$10,000
$10,000
$10,000
$2,500
$12,500
$192,150
Total Cost (Net Present Value)
I.
$1,422,540
Ol-Aut-9!
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Table 4B--Landfill Gas Contingency-Horizontal Trench System (Open Flare)
Item
Capital Costs
Install Trench System
Mobilization/Demobilization
Horizontal Trenching and Pipjng_
Flare and Blower
Subtotal Capita! Costs
EPA Oversight
Contractor Overhead and Profit (10%)
Engineering (15%)
Contingencyl25%)_
Total Capital Costs
Operation & Maintenance (O&M) Costs
Flare and Blower Maintenance
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%)
Total Cost (Net Present Value)
Quantity
1
85,400
1
1/yr
Units
LS
LF
EA
LS
.
Unit Cost
$20,000
$25
$160,000
$75,000
Cost I
$20,000
$2,135,000
$160,000
$2,315,000
$72,220
$231,500
$347,250
$578,750
$3,544,720
$75,000
$75,000
$18,750
$93,750
$1,441,-125
$4,985,845
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Table 4C-Landfill Gas Contingency-Horizontal Trench System (Enclosed Flare)
Item
Capital Costs
Install Trench System
, Mobilization/Demobilization
Horizontal Trenching and Piping
Flare and Blower
Subtotal Capital Costs
EPA Oversight
Contractor Overhead and Profit (10%)
Engineering (15%)
Contingency (25%)
Total Capital Costs
Operation & Maintenance (O&M) Costs
Flare and Blower Maintenance
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%) ,
Total Cost (Net Present Value)
Quantity
1
85,400
1
1/yr
Units
LS
LF
EA
LS
Unit Cost
$20,000
$25
$200,000
$80,0.00
Cost I
•
$20,000
$2,135,000
.$200,000
$2,355,000
$86,660
$235,500
$353,250
$588,750
$3,619,160
$80,000
$80,000
$20,000
$100,000
$1,537,200
$5,156,360
OI-Aug-9!
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Table 4D--Landfill Gas Contingency-Vertical Well System (Open Flare)
Item
Capital Costs
Install Well System
Mobilization/Demobilization
Vertical Wells
Flare and Blower
Subtotal Capital Costs
EPA Oversight
Contractor Overhead and Profit (10%)
Engineering (15%)
Contingency (25%)
Total Capital Costs
Operation & Maintenance (O&M) Costs
Flare and Blower Maintenance ' .
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%)
Total Cost (Net Present Value)
Quantity
1
640
1
1/yr
Units
LS
EA
EA
LS
Unit Cost
$15,000
, $2,500
$160,000
$95,000
Cost
•
$15,000
$1,600,000
$160,000
$1,775,000
$72,220
$177,500
$266,250
$443,750
$2,734,720
$95,000
$95,000
$23,750
$118,750
$1,825,425
$4,560,145
95-989 XK3
01-AUK--)!
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Table 4E--Landfill Gas Contingency-Vertical Well System (Enclosed Flare)
Item
Capital Costs
Install Well System •,
Mobilization/Demobilization I
Vertical Wells
Flare and Blower
Subtotal Capital Costs d
EPA Oversight j
Contractor Overhead and Profit H0%)
Engineering (15%)
Contingency (25%)
Total Capital Costs
Operation & Maintenance (O&M) Costs
Flare and Blower Maintenance
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%)
Total Cost (Net Present Value)
Quantity
1
640
1
}
1/yr
L Units
LS
EA
EA
LS
Unit Cost
$15,000
$2,500
$200,000
I $105,000
Cost
•
$15,000
$1,600,000
$200,000
$1,815,000
$86,660
$181,500
$272,250
$453,750
$2,809,160
$105,000
L $105,000
$26,250
$131,250
$2,017,575
$4,826,735
OI-Auj-9:
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Table 4F--Landfill Gas Contingency-Surface Collection System (Open Flare)
Item ~
Capital Costs
Install Collection System
Mobilization/Demobilization
Sand Layer (6" Vent Layer)
Vents Q/Acre) Includes Overland Pipe
Flare and Blower
Subtotal Capital Costs
EPA Oversight
Contractor Overhead and Profit (10%)
Engineering (15%)
Contingency (25%)
Total Capital Costs
Operation & Maintenance (O&M) Costs
Flare and Blower Maintenance
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%)
Total Cost (Net Present Value)
Quantity
1
120,000
147
1
1/yr
Units
LS
CY
EA
EA
LS
Unit Cost
$20,000
$6
$1,000
$160,000
$60,000
Cost ]
•
$20,000
$720,000
$147,000
$160,000
$1,047,000
$72,220
$104,700
$157,050
$261,750
$1,642,720
$60,000
$60,000
$15,000
$75,000
$1,152,900
$2,795,620
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Table 4G--Landfill Gas Contingency-Surface Collection System (Enclosed Flare)
Item
Capital Costs
Install Collection System
Mobilization/Demobilization
Sand Layer (£>" Vent Layeil
Vents (1/AcreJ Includes Overland Pipe
Flare and Blower
Subtotal Capital Costs
EPA Oversight
Contractor Overhead and Profit |10%)_
Engineering (15%}_
Contingency (25%)
Total Capital Costs
Operation & Maintenance (O&M) Costs
Flare and Blower Maintenance
Subtotal O&M Costs
Contingency (25%)
Total O&M Costs
Net Present Value of O&M Costs (30 years, 5%)
Total Cost (Net Present Value)
Quantity^
1
120,000
147
1
1/yr
Units
LS
CY
EA
EA
LS
Unit Cost
$20,000
I $6
$1,000
$200,000
$65,000
Cost I
•
$20,000
$720,000
$147,000
$200,000
I $1,087,000
$72,220
$108,700-
$163,050
$271,750
$1,702,720
$65,000
$65,000
$16,250
$81,250
$1,248,975
$2,951,695
95.989.WK3
OI-AUJ-9J '.,'•
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Interim Remedial Action ROD
APPENDIX C
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Appendix C:
Guidance Documents for the
Landfill Cover System
Solid Waste Landfill Design Manual, June 1987, Publication No.87-
13.- Prepared by Parametrix, Inc. for Washington Department of
Ecology.
Technical Guidance Document: Final Covers on Hazardous Waste
Landfills and Surface Impoundments, EPA/530-SW-89-047.
Technical Guidance Document: The Fabrication of Polyethylene FML
Field Seams, EPA/530/SW-89-069.
Seminar Publication Design and Construction of RCRA/CERCLA Final
Covers, EPA/625/4-91/025.
Technical Guidance Document: Inspection Techniques for the
Fabrication of Geomembrane Field Seams, EPA/530/SW-91/051.
Solid Waste Disposal Facility Criteria Technical Manual, EPA 530-
R93-017.
Technical Guidance Document: Quality Assurance and Quality
Control for Waste Containment Facilities, EPA/600/R-93/182.
Report of Workshop on Geosynthetic Clay Liners, EPA/600/R-93/171.
Proceedings of the Workshop on Geomembrane Seaming Data
Acquisition and Control, EPA/600/R-93/112.
The Hydrologic'Evaluation of Landfill Performance (HELP) Model
User's Guide for Version 3, EPA/600/R-94/168a.
The Hydrologic Evaluation of Landfill Performance (HELP) Model
Engineering Documentation for Version 3, EPA/600/R-94/168b.
C-l
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Interim Remedial Action ROD
APPENDIX D
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RESPONSIVENESS SUMMARY
TULALIP LANDFILL
TABLE OF CONTENTS
1.0 OVERVIEW
2.0 GENERAL LEGAL/POLICY ISSUES
3.0 CWA AND PRE-CERCLA CLOSURE HISTORY
4.0 NPL LISTING
5.0 TRIBES7ROLE
6.0 ARARS
7.0 HR 2099
8.0 CONSISTENCY WITH OTHER SITES
9.0 HYDROGEOLOGICAL ISSUES
10.0 DATA QUALITY/DATA EVALUATION
11.0 STREAMLINED BASELINE RISK ASSESSMENT FOR INTERIM
REMEDIAL ACTION
General Comments
Human Health Evaluation Comments
Ecological Evaluation Comments
Data Use/Interpretation Comments
Background Issues
Dilution/Mixing Zone Issues
12.0 COMPREHENSIVE BASELINE RISK ASSESSMENT
13.0 SELECTION OF PRESUMPTIVE REMEDY/REMEDIAL ALTERNATIVES
14.0 MICROBIOLOGICAL STUDIES
15.0 FUTURE SITE STUDIES
16.0 MISCELLANEOUS COMMENTS
ATTACHMENT A: De-MJNIMIS SETTLEMENT AND OTHER LIABILITY
COMMENTS
ATTACHMENT B: FIGURES 4-1 AND 4-2
ATTACHMENT C: LIST OF REFERENCES
D-l
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LIST OF COMMENTORS
As part of the formal remedy selection process, public
comments were solicited on EPA documents related to the
Proposed Plan for Interim Remedial Action at the
Tulalip Landfill. All public comments received are
contained in the following documents:
1. Transcript from the Public Meeting of August 22,
1995
2. Transcript from the Public Meeting of October 3,
1995
3. AOC Respondents Comments on EPA's Proposed Plan
for Interim Remedial Action at the Tulalip
Landfill
4. Letter from Snohomish Health District
5. Letter from Balance Council
6, Letter from Sato Corporation
7. Letter from NW Indian Fisheries Commission
8. Letter from Lake Union Drydock Company
••*•*•
9. Letter from Achilles USA Inc.
10. Letters from the Tulalip Tribes
11. Letter from People for Puget Sound
12. Comment sheet froflT Mark Lindberg
13. Letter from Fog-Lite
14. Letter from Buffalo Industries
15. Telephone logs from unidentified private citizens
16. Letter from Pilchuck Audubon Society
17. Letter from Crow Roofing and Sheet Metal, Inc.
18. Letter from Marco Shipyard
D-2
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TERMS COMMONLY USED IN THE RESPONSIVENESS SUMMARY
The following is a list of terms and unique definitions
as used throughout the Responsiveness Summary. EPA is
including these definitions for purposes of clarity.
a. source or on-source area -- is considered to
include approximately 147 acres of waste,
groundwater in and beneath the waste, cover
material and the surrounding perimeter landfill
berm.
b. off-source area -- is considered to include
any part of the Site that is located outside the
perimeter berm.
c. streamlined baseline risk assessment -- refers
to the risk assessment performed for the on-source
area of the Tulalip Site as part of the remedial
investigation and remedy selection process (i.e.,
the RI/FS). In the Proposed Plan and the Risk
Assessment for Interim Remedial Action, EPA
referred to the risk assessment and its process as
a "screening" assessment. After evaluating public
comments on the Proposed Plan, it is apparent that
some commentors were misled by EPA's use of the
phrase "screening" to refer to the risk assessment
process used for evaluating the on-source area of
the Tulalip Site. Therefore, EPA is now more
appropriately and accurately referring to the risk
assessment for the source area as a Streamlined
Risk Assessment, rather than a screening level
risk assessment. The Streamlined Risk Assessment
has been completed.
d. comprehensive baseline risk assessment (CBRA)
-- refers to the risk assessment for the off-
source area of the Tulalip Site. This risk
assessment is ongoing.
e. interim (action) ROD -- refers to the remedial
action decision document for the on-source area of
the Site.
f. cap/cover -- refers to a component of the
selected remedial action. A cap or cover are
terms used to describe a method of containment
which employs a covering or cap to prevent contact
exposure or infiltration of precipitation.
D-3
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g. Zone 1 aquifer -- refers to the leachate mound
which has accumulated in the refuse layer. When
precipitation falls on the landfill, most of the
rainwater infiltrates down through the soil cover
and sinks down into the refuse layer, picking up
contamination from the waste as it moves through.
A discontinuous silt layer underlies the refuse
and the Zone 1 aquifer throughout much of "the
landfill.
h. Zone 2 -- refers to the groundwater under Zone
1 and the discontinuous silt layer.
i. comparison numbers -- refers to established
standards and criteria, and calculated risk-based
chemical concentrations, that are generally
considered to be protective of human health and
the environment. Most of these comparison
numbers, with the exception of ecological soil
risk-based concentrations, have been established
or developed under federal or state law.
After evaluating public comments on the Proposed
Plan, it is apparent to EPA that some commentors
were.mislead by EPA's use of the phrase "screening
criteria" in the Streamlined Risk Assessment to
refer to standards, criteria and risk-based
chemical concentrations used in the Streamlined
Risk Assessment. To clarify this issue, EPA is
using a more accurate phrase "comparison numbers"
to refer to standards, criteria and risk-based
chemical concentrations. EPA notes that these
comparison numbers have been selected for use in
the Streamlined Risk Assessment for the purpose of
evaluating potential risks posed by the Site.
These comparison numbers are not necessarily
ARARs.
j. AOC Respondents -- generally refers to the
Potentially Responsible Parties (PRPs) who signed
the RI/FS Administrative Order on Consent, dated
August 1993.
D-4
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LIST OF ACRONYMS USED IN THIS DOCUMENT
AET
AMBS
AOC
AR
ARAR
ASTM
AWQC
BIA
CBRA
CCMP
C.F.R.
EPA
FML
FS
FWQC
MCC
MFS
MTCA
NCP
NEP
NPL
O&M
Apparent Effects Threshold
Area of Major Biological Significance
Administrative Order on Consent
Administrative Record
Applicable or Relevant and Appropriate
Requirements
American Society for Testing and
Materials
Ambient Water Quality Criteria
Bureau of Indian Affairs
Comprehensive Baseline Risk Assessment
Comprehensive Coastal Management Plan
Code of Federal Regulations
United States Environmental Protection
Agency
Flexible Membrane Liner
Feasibility Study
Federal Water Quality Criteria
Marine Chronic Criteria
Minimal Functional Standards (Washington
State MFS regulations for landfill
closure)
Model Toxics Control Act
National Contingency Plan
National Estuary Program
National Priorities List
Operation and Maintenance
D-5
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ou
NPDES
POTW
PP
PRPs
QA/QC
QAPP
RAO
RBC
RCW
RI
ROD
REAC(Weston)
SDC
SRA
SMS
SQS
TOC
TRY
WAG
WQS
U.S.C.
Operable Unit
National Pollutant Discharge Elimination
System
Publicly Owned Treatment Works
Proposed Plan
Potentially Responsible Parties
Quality Assurance/Quality Control
Quality Assurance Project Plan
Remedial Action Objectives
Risk-Based Concentrations
Revised Code of Washington
Remedial Investigation
Record of Decision
Response Engineering and Analytical
Contract
Seattle Disposal Company
Streamlined Baseline Risk Assessment
Sediment Management System
Sediment Quality Standards - —
Total Organic Content
Toxicity Reference Value
Washington Administrative Code
Water Quality Standards
United States Code
D-6
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RESPONSIVENESS SUMMARY
FOR THE
TULALIP LANDFILL
INTERIM ROD
1.0- OVERVIEW
This section provides a "roadmap" of the Agency's
decision making process regarding the interim remedial
action at the Tulalip Landfill and a brief discussion
of the organization of the Responsiveness Summary.
1.1 PERSPECTIVE ROADMAP FOR DECISIONMAKING
This "roadmap" of the Agency's decision-making (1)
shows how presumptive remedy approach works, (2) why
Tulalip fits into that approach and why it is
appropriate for Tulalip, (3) explains how all
alternatives were examined using the nine criteria,
including ARARs (how identified, how considered, how
they apply and why selected remedy is protective), (4)
why selected remedy makes technical (engineering) sense
at Tulalip, and (5) briefly defines a streamlined
baseline risk assessment and how it differs from a
comprehensive baseline risk assessment.
EPA's use of the presumptive remedy approach at the
Tulalip Landfill site is a reasonable approach to
address the threats posed by the hazardous substances
contained in the landfill and landfill leachate. Under
the guidance document entitled "Presumptive Remedy for
CERCLA, Municipal Landfill Sites," OSWER Dir. No.
9355.0-49FS, September 1993 ("Presumptive Remedy
Guidance") (EPA, 1993a), EPA explains why it believes
that the presumptive remedy approach works for
municipal landfills and can be used by EPA as a tool to
streamline the decision-making process at the RI/FS
stage at municipal landfill sites. In the Presumptive
Remedy Guidance, EPA states that containment is the
presumptive remedy for municipal landfills. The
containment presumptive remedy consists of various
components, which may include a landfill cap, source
area ground-water control, leachate collection and
treatment, landfill gas collection and treatment,
and/or institutional controls to supplement engineering
controls. Id. at 2. EPA's Office of General Counsel
has written a memorandum which explains the
relationship between EPA's presumptive remedy
initiative and the requirements contained in the
National Contingency Plan ("NCP"), and has determined
D-7
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that the use of the presumptive remedy concept at
CERCLA sites is consistent with the NCP requirements.
See Memorandum from James E. Costello and George B.
Wyeth entitled "Presumptive Remedies and NCP
Compliance", dated June 14, 1995 (EPA, 1995a).
However, in order to determine whether the Tulalip
Landfill is a good "fit" for the use of a presumptive
remedy, EPA Region 10 had to evaluate the site-specific
conditions at Tulalip. A summary of this decision-
making process is set out below.
First, Region 10 examined the reasons given in the
Presumptive Remedy Guidance as to why the presumptive
remedy approach works for municipal landfills and to
see if that approach would work at Tulalip. The
Guidance on page 2 states that:
"Section 300.430 (a) (iii) (B) of the NCP
contains the expectation that
engineering controls, such as
containment, will be used for waste that
poses a relatively low long-term threat
or where treatment is impracticable.
The preamble to the NCP identifies
municipal landfills as a type of site
where treatment of the waste may be
impracticable because of the size and
heterogeneity of the contents (55 Fed.
Reg. 8704). Waste in CERCLA landfills
usually is present in large volumes and
is a heterogeneous mixture of municipal
waste frequently co-disposed with
industrial and/or hazardous waste.
Because treatment usually is
. impracticable, EPA" generally considers
containment to be the appropriate
response action, or the 'presumptive
remedy,' for the source areas of
municipal landfill sites." •• -
EPA Region 10 then examined the site characterization
data, and concluded that the characteristics of the
Tulalip Landfill were substantially similar to those at
landfill sites where the use of the presumptive remedy
has been deemed appropriate by EPA. See "Application
of Presumptive Remedy at Tulalip Landfill" memorandum
from E. McKenna, Assistant Regional Counsel, EPA Region
10, to the Tulalip Landfill File (August 4, 1995),
(McKenna, 1995) located in the AR for the Tulalip
Landfill Site. The Tulalip Landfill covers a large
area of approximately 146 acres in Ebey Island on the
Tulalip Indian Reservation. Between 1964 and 1979,
D-8
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approximately three to four million tons of mixed
commercial and industrial waste was deposited in the
landfill. , Surveys show the waste is relatively evenly
distributed at an average depth of 17 feet over the 147
acre landfill, with the depth of waste in the barge
canals averaging approximately 30 feet. There were no
records kept at the landfill regarding the exact
location or exact types of wastes deposited in the
landfill. Thus, it is impossible to determine specific
"hot spot" areas of contamination associated with the
landfill contents. Hazardous substances .found in
surface soils at the Site exceeded comparison numbers
in one or more samples at eight of the nine leachate
soil grid locations. At six of the leachate soil grid
locations, subsurface soil samples were collected.
Hazardous substances found in these subsurface soils
exceeded comparison numbers in five of the six
subsurface soil samples. Hazardous substances detected
in leachate exhibited at least one exceedance of the
Washington State Marine Chronic Criteria ("MCC") in
most of the eleven leachate seeps that were tested.
Groundwater under the landfill is contaminated at
levels exceeding Washington State Water Quality
Standards ("WQS") (HLA, 1995; Weston, 1995b). Thus, it
is clear that the Tulalip Landfill is a heterogenous
source of hazardous substances at levels exceeding
comparison numbers, and that these hazardous substances
appear to be randomly distributed throughout the
landfill. As such, Region 10 determined that the
Tulalip Landfill was substantially similar to other
landfills where EPA has applied the presumptive remedy
concept, and that the Tulalip Landfill was indeed a
good "fit" within the Presumptive Remedy Guidance
guidelines.
The NCP remedy selection process involves several
steps, including: (1) characterizing the risks
presented by a site, (2) screening technologies for
possible remediation, and (3) performing a detailed
analysis of those technologies that appear most
promising. The screening step is based on three
criteria (effectiveness, implementability, and cost),
and is designed to exclude those technologies which are
clearly inferior. The identification of presumptive
remedies serves, in effect, to carry out the screening
step in a generic manner. Thus, the presumptive remedy
for municipal landfills identifies containment as the
presumptive remedy, and it provides components of the
containment remedy (e.g, a cap, leachate collection)
for EPA to then analyze on a site-specific basis using
the nine NCP remedy selection criteria in order to
develop remedial alternatives for the site. To that
D-9
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end, EPA Region 10 used the presumptive remedy of
containment (and its components), along with
alternatives suggested by other parties, to develop and
analyze remedial alternatives at the Tulalip Landfill
Site.
As part of this analysis of the Tulalip Landfill,
Region 10 then determined that the source area of the
Tulalip Landfill was an appropriate candidate for the
use of a streamlined risk assessment. The preamble to
the NCP states that risk assessments "...are site-
specific and therefore may vary in the extent to which
qualitative analyses are utilized, depending upon the
complexity and particular circumstances of the site, as
well as the availability of pertinent ARARs and other
criteria, advisories, or guidance." See 55 Fed. Reg.
at 8709.
EPA prepared a streamlined baseline risk assessment
(Streamlined Risk Assessment) to facilitate evaluation
of the need for potential early actions necessary to
address contaminant migration from the Tulalip
Landfill. Preparation of a streamlined risk
assessment, as opposed to a comprehensive baseline risk
assessment, is considered appropriate when addressing
the potential risks associated with landfills because
options for remedial action at landfill site source
areas are traditionally limited to methods of
containment. A streamlined risk assessment is a
qualitative evaluation, based on comparison of site-
related contaminant concentrations to available
standards or risk-based chemical concentrations. The
purpose of this type of evaluation is to assess the
frequency and magnitude of exceedances of these
comparison numbers and to use this information to
assist in evaluating the need, or lack of need, for
early action.
A comprehensive baseline risk assessment provides a
quantitative evaluation of potential risk due to all
chemicals in all media of concern considering site-
specific exposure assumptions and a detailed evaluation
of chemical concentrations. The Tulalip streamlined
risk assessment is a qualitative evaluation of the
frequency and magnitude of exceedance of comparison
numbers considered to be protective of human health and
the environment, based on standard exposure
assumptions, and a qualitative evaluation of potential
risks.
EPA has developed a fact sheet containing guidance for
preparing streamlined risk assessments (OSWER Directive
D-10
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No. 9355.3-11FS, September, 1990) (EPA, 1990a).
According to this guidance, a simple comparison of
site-related chemical concentrations to available
comparison numbers is sufficient to warrant remedial
action. EPA went beyond this requirement in
preparation of the streamlined risk assessment for the
Tulalip Landfill by providing a critical evaluation of
the relevance of available standards and by
incorporating a comparison of site-related
concentrations to regionally-available background
concentrations. This was done to provide a more
accurate evaluation of the need for early action.
EPA's Presumptive Remedy Guidance on page 5 states
that .-
"[a]s a matter of policy, for the source
area of municipal landfills, a
quantitative risk assessment that
considers all chemicals, their potential
additive effects, etc., is not necessary
to establish a basis for action if
ground-water data are available to •
demonstrate that contaminants clearly
exceed established standards or if other
conditions exist that provide a clear
— justification for action."
"Finally, a quantitative risk assessment
is not required to determine clean-up
levels because the type of cap will be
determined by closure ARARs, and ground-
water that is extracted as a component
of the presumptive remedy will be
required to meet discharge limits, or
other standards for its disposal."
At the Tulalip Landfill, the Region decided that a
streamlined risk assessment was appropriate because
during the scoping process, EPA and the Respondents
agreed that the best way to structure the RI/FS was to
adopt the presumptive remedy approach for the source
area of the landfill. Under EPA's Presumptive Remedy
Guidance, EPA can streamline the risk assessment
process for solid waste landfills in cases where the
presumptive remedy approach is appropriate. In the
RI/FS workplan (which is part of the RI/FS AOC), the
Tulalip Landfill was deemed appropriate for remedial
action because concentrations of contamination at the
landfill exceeded federal AWQC.
D-ll
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In contrast to all of the sites referenced by the
commentor, the Tulalip Landfill is an appropriate
candidate, for the use of the presumptive remedy for
municipal landfills. According to an EPA memorandum
from James Costello and George Wyeth of EPA's Office of
General Counsel entitled "Presumptive Remedies and NCP
Compliance," June 14, 1995 (EPA, 1995a), "[t]he use of
presumptive remedies follows the NCP remedy selection
process because the identification of presumptive
remedies serves, in effect, to carry out the screening
and detailed analysis steps in a generic manner that
minimizes the need to perform those steps at a site-
specific level." Id. at 3.
Containment is the presumptive remedy which was found
to be most commonly suited for municipal landfills
because these landfills, as well the Tulalip
Landfill1, share the following characteristics: (1)
large volume and heterogeneity of waste which make
treatment impracticable; (2) limited number of
alternatives for controlling releases; (3) similar
potential threats to human health and the environment
resulting from leachate generation, soil contamination,
landfill contents, landfill gases, and contamination of
groundwater, surface water, sediments and adjacent
wetlands; and (4) the nature of waste deposition. See
generally "Presumptive Remedy for CERCLA Municipal
Landfill Sites," OSWER Dir. No. 9355.0-49FS, September
1993 ("Presumptive Remedy Guidance"). Because the
Tulalip Landfill shares these characteristics with
municipal landfills and EPA is unaware of any technical
reasons for not applying the municipal landfill
presumptive remedy guidance, EPA has concluded that the
presumptive remedy approach is appropriate for the
Tulalip Landfill.
Pursuant to EPA's Presumptive Remedy Guidance,
containment remedies usually include installing a low
permeability cover to keep rain water from filtering
down through the wastes in the landfill. Containment
may also include some form of leachate collection and
treatment, some form of landfill gas collection, or
some form of groundwater control. The preferred
remedial alternative as set forth in the Proposed Plan
for the Tulalip Landfill is installation of a low
permeability cover over the waste. This alternative
would be expected to be effective in minimizing the
1 While EPA considers the Tulalip Landfill to be a solid waste landfill
but not a municipal landfill, the Agency believes that using the municipal
landfill presumptive remedy guidance at the Tulalip Landfill is appropriate.
D-12
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migration of contaminated groundwater from the source
area. Since the FS shows that the low permeability cap
will minimize the generation of leachate by virtually
eliminating the movement of contaminated groundwater to
surface water, the Proposed Plan recommends taking no
further action to remediate groundwater.
The Presumptive Remedy Guidance recognizes that almost
every municipal landfill site has some characteristics
that may require additional study. For example, such
characteristics may include leachate discharge to a
wetland or significant water run-off caused by drainage
problems, which will require more comprehensive
characterization and a more comprehensive risk
assessment to determine what, if any, additional
remedial action is necessary. At the Tulalip Landfill,
EPA is expected to complete a comprehensive baseline
risk assessment in the summer of 1996. This
comprehensive baseline risk assessment will examine the
leachate discharges to the sensitive, ecologically
valuable wetlands that surround the Landfill and to the
"sloughs adjacent to the Landfill. To that end, the FS
for this site is being conducted in two parts: one for
the containment alternatives, and one for the off-
source alternatives. This analysis of the wetlands
will not require a modification to this interim action
because any impacts that may be occurring or have
occurred to these wetlands can be addressed separate
and apart from this interim action, and this interim
action is needed to control the overall contaminant
loading of the wetlands and sloughs that is presently
occurring.
Under the source area FS, the Respondents' contractor,
with Region 10 input,- developed_and analyzed remedial
alternatives, using the nine NCP remedy selection
criteria. As part of this process, the FS identified
potential'applicable or relevant and appropriate
requirements ("ARARs") from federal and state
environmental laws. Section 121 of CERCLA requires
that a remedial action attain all standards specified
in the ARARs identified for a given site, or a
justification must be provided in the ROD for waiving
the requirement to attain the ARAR. In addition,
compliance with ARARs is one of the two threshold NCP
remedy selection criteria, the other being
protectiveness of human health and the environment.
At the Tulalip Landfill site, Region 10 considered all
federal, tribal and state ARARs when it examined the
various remedial alternatives and chose Alternative 4c
as the selected remedy. EPA's selection of alternative
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4c as the preferred alternative is justified, as
alternative 4c meets all ARARs identified for the
Tulalip Landfill and is protective of human health and
the environment. -For example, EPA identified the state
of Washington landfill closure requirements contained
in the Minimal Functional Standards ("MFS") in WAG 173-
304 as an ARAR for the source area of the landfill.
The state's MFS for closure were determined to be
relevant and appropriate requirements because those MFS
govern closure of municipal solid waste landfills and
are more stringent than the federal solid waste
landfill closure requirements codified at 40 C.F.R.
§ 258.60. Since Region 10 had decided that the Tulalip
Landfill was substantially similar to a municipal solid
waste landfill, the closure MFS contained in WAG 173-
304 were deemed to be relevant and appropriate for the
Tulalip Landfill. These MFS for landfill closure are
protective of human health and the environment as they
are designed to prevent infiltration of precipitation
into the landfill which thereby minimizes the
generation of landfill leachate containing hazardous
substances. Since minimization of landfill leachate at
the Tulalip Landfill is one of the primary remedial
action objectives in this interim action, the MFS for
landfill closure are a necessary requirement which are
met by the selected alternative, 4c. See Section 11.2
of the ROD for a more detailed discussion and analysis
of the ARARs for this site.
In addition, the selected remedy also makes engineering
and environmental sense. Of all of the alternatives
considered by EPA, a geosynthetic cover with passive
drainage is the least expensive containment alternative
that will effectively stem the generation and flow of
contaminated leachate into the surface waters
surrounding the landfill. This containment remedy
relies on a "passive" design that does not require
pumps or outside power to control surface water
drainage. A low permeability cover is implementable as
a well-known technology, and is expected to be
effective in the long-term, with established means to
monitor and maintain the cover. The selected remedy
will reliably achieve the remedial action objectives of
reducing risks without the need for establishing
elaborate contingency measures to plan for the possible
failure of less certain measures. The cover will also
allow for future use of the Site, with certain
institutional controls required to protect the
integrity of the cover. In addition, because the
selected remedy is expected to virtually eliminate
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migration of leachate into the deeper Zone 2 aquifer,
further remediation of Zone 2 groundwater will not be
necessary, after implementation of this selected interim
remedy.
1.2 ORGANIZATION OF THE RESPONSIVENESS SUMMARY
EPA received a large number of comments from the AOC
Respondents regarding the Proposed Plan for Interim
Remedial Action at the Tulalip Landfill in Marysville,
Washington. EPA has summarized all comments in detail
and presented a response to each comment.2 EPA has
attempted to summarize the comments as accurately as
possible. EPA decided to present all comments in
detail to ensure the Agency's response is complete;
consequently, the Responsiveness Summary is similar to
the comments in its voluminous and detailed nature.
Comments were organized into categories for inclusion
in the Responsiveness Summary. The categories are
listed in the "Table of Contents" on page D-l of this
Responsiveness Summary. The organizational flow of the
Summary by category begins with legal and regulatory
policy comments, and then moves into a presentation of
the more technical comments. Within each category, the
Agency organized comments by various subtopics, or by
addressing the more overarching comments for that
category first and then proceeding to the more detailed
comments for that category. _
2.0 GENERAL LEGAL/POLICY ISSUES
2.1 Comment: "B.I. CERCLA and the NCP require the
completion of a baseline risk assessment prior to the
development and evaluation of remedial alternatives and
the selection of any remedial action at the site." [1]
[2] [3]
2.1.1 Additional Comments under Comment B.I.: The commentor
also states that CERCLA "limits EPA's response action
authority to circumstances where there is an imminent
and substantial danger to public health, welfare, or
the environment due to actual or threatened releases
from a site." The commentor goes on to say that "any
response measures undertaken by EPA, including the
2 EPA has assigned each commentor a number. A bracketed number appears
after each comment that identifies the commentor(s). The list of commentors
and their identifying number is located in the "List of Commentors" on page D-
2 of this Responsiveness Summary.
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selection of appropriate remedial action, must be
determined to be necessary, and also consistent with
the National Contingency Plan ("NCP")." Finally, the
commentor concludes that "unless site risks have been
properly evaluated and established, EPA has no
authority to take response action itself or to order
others to respond to an actual or threatened release."
Response: The commentor is incorrect in stating that
EPA may only respond in circumstances presenting an
imminent and substantial danger. Section 104(a)(1) of
CERCLA authorizes a response action whenever "(A) any
hazardous substance is released or there is a
substantial threat of such release into the
environment, or (B) there is a release or substantial
threat of release into the environment of any pollutant
or contaminant which may present an imminent and
substantial danger to the public health or welfaret.]"
(emphasis added) 42 U.S.C. § 9604 (a) (1). In this case,
the release of many different hazardous substances into
the environment has been documented in the RI/FS that
is in the AR. For example, data in the RI/FS shows
that there are 1367 exceedances of comparison numbers.
Because there are documented releases of hazardous
substances on the Site, EPA may undertake a response
action at the Site regardless of whether those releases
pose an imminent and substantial danger to the public
health or welfare. However, these releases of
hazardous substances may present an imminent and
substantial danger to human health and the environment.
See Section 6.3 of the Tulalip Landfill Interim Action
Record of Decision ("interim (action) ROD"), which
states that "[c]omparison of the site measured chemical
concentrations to the human health risk-based and
ecological effects-based standards and criteria
established under other environmental laws, and risk-
based concentrations reveals potential risks to humans
and the environment. Based on the RI/FS and findings
in the risk assessment, EPA finds that actual or
threatened releases of hazardous substances from the
Site, if not addressed by the selected alternative or
one of the other active measures considered, may
present an imminent and substantial endangerment to
public health, welfare, or the environment."
Section 121 of CERCLA, 42 U.S.C. § 9621, governs
cleanup standards and selection of remedial actions.
Section 121(a) states in part that:
"The President shall select appropriate
remedial actions determined to be necessary
to be carried out under section 9604 of this
D-16
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title or secured under section 9606 of this
title which are in accordance with this
section and, to the extent practicable, the
national contingency plan, and which provide
for cost-effective response."
As is demonstrated in the AR, and as explained in this
responsiveness summary, EPA has fully complied with its
statutory requirements. The commentor mistakenly
concludes that site risks must be "evaluated and
established" through a baseline risk assessment before
EPA can take a response action itself or order others
to respond to an actual or threatened release. As
discussed above, the only requirement for EPA to take a
response action is if there is a release or threat of a
release of a hazardous substance. And as will be
explained below, EPA has fully complied with the
requirements of the NCP by selecting a remedial
alternative based on a completed streamlined baseline
risk assessment prior to the completion of a
comprehensive baseline risk assessment. See, also.
Response to Comment 2.1.2, below.
2.1.2 Additional Comment under B.I.: The commentor also
states that the "NCP requires EPA or potentially
responsible parties, as part of the Remedial
Investigation process and prior'to any remedy
selection, to conduct a baseline risk assessment that
characterizes the nature and extent of threats to human
health and the environment." [8] [17] [18]
Response: EPA has completed a streamlined baseline
risk assessment, entitled the "Final Tulalip Landfill
Risk Assessment for Interim Remedial Action," August
1995, (EPA, 1995d), (the "Streamlined Risk
Assessment"), which is sufficient to support selection
of an interim containment remedy at this Site. The NCP
does,not require a more comprehensive baseline risk
assessment than the one EPA has completed in order to
take the type of action that EPA is selecting for the
Source Area of the Site. The NCP requires a balancing
process to be employed in deciding whether early action
is appropriate at a site. This balancing process
involves weighing the need for prompt, early actions
against the need for definitive site characterization.
This balancing process is specifically linked to the
RI/FS, including the risk assessment, at 40 C.F.R.
§ 300.430(a) (2) :
"Developing and conducting an RI/FS
generally includes the following
activities: project scoping, data
D-17
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collection, risk assessment,
treatability studies, and analysis of
alternatives. The scope and timing of
these activities should be tailored to
the nature and complexity of the problem
and the response alternatives being
considered." (Emphasis added).
The preamble to the 1990 revisions to the NCP states:
"EPA expects to take early action at
sites where appropriate, and to
remediate sites in phases using operable
units as early actions to eliminate,
reduce or control the hazards posed by a
site or to expedite the completion of
total site cleanup. In deciding whether
to initiate early actions, EPA must
balance the desire to definitively
characterize site risks and analyze
alternative remedial approaches for
addressing those threats in great detail
with the desire to implement protective
measures quickly. Consistent with
today's management principles, EPA
intends to perform this balancing with a
bias for initiating response actions
necessary or appropriate to eliminate,
reduce, or control hazards posed by a
site as early as possible" (Emphasis
added). 55 Federal Register 8704 (March
8, 1990).
The Streamlined Risk Assessment reflects the nature and
complexity of the problem and the response alternatives
considered. EPA balanced the need for action based on
its evaluation of existing data and the nature of the
Site against the need to develop more data as the basis
of a more comprehensive risk assessment. EPA has
determined that the selected containment remedy is
appropriate given the risks known to exist at the Site
as evaluated in the Streamlined Risk Assessment.
The commentor asserts that the Streamlined Risk
Assessment does not provide the level of detail to
satisfy the fundamental purpose of a baseline risk
assessment. The preamble to the NCP and guidance
documents provide more detailed information on how EPA
suggests risk assessments may be conducted at Superfund
sites of varying scope and complexity. A close
examination of these sources shows that the Streamlined
Risk Assessement is consistent with EPA's policy for
D-18
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sites of similar scope and complexity to the Tulalip
Landfill Site and, does in fact, meet minimum
requirements for risk assessment.
"To implement an early action under the
remedial authority, an operable unit for
which an interim action is appropriate is
identified. Data sufficient to support the
interim action decision is extracted from the
ongoing -RI/FS that is underway for the site
or final operable unit and an appropriate set
of alternatives is evaluated...A completed
baseline risk assessment generally will not
be available or necessary to justify interim
action.
* * *
"Qualitative risk information should be
organized that demonstrates that the action
is necessary to stabilize the site, prevent
further degradation, or achieve significant
risk reduction quickly. See 55 Federal
Register 8704 (March 8, 1990) (Emphasis
added).
The Streamlined Risk Assessment provides data
"sufficient to support the interim action" decision.
As quoted above, the supporting data may be extracted
from the "ongoing RI/FS" and an "appropriate set of
alternatives" may be evaluated prior to the issuance of
a completed baseline risk assessment. The NCP clearly
envisioned a situation such as this where information
from the ongoing RI was used to complete a risk
assessment which provides the basis for remedial action
to stabilize that specific area of the Site.
Consistent with the NCP, EPA plans to complete a
comprehensive baseline risk assessment which will be
used to evaluate whether additional cleanup actions
will be needed for the off-source area, after a
containment action for the source area has been
selected.
EPA's "Risk Assessment Guidance For Superfund, Volume
1, Human Health Evaluation Manual (Part A)," December
1989 (EPA, 1989a), further elaborates on the principle
that varying levels of detail are required in risk
assessments, depending on the timing of the action to
be taken at a Site:
"Although risk information is
fundamental to the RI/FS and to the
D-19
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remedial response program in general,
Superfund site experience has led EPA to
balance the need for information with
the need to take action at sites quickly
and to streamline the remedial process.
Revisions proposed to the NCP in 1988
reflect EPA program management
principles intended to promote the
efficiency and effectiveness of the
remedial response process. Chief among
these principles is a bias for action."
See page 1-1.
"Baseline risk assessments are site-specific
and therefore may vary in both detail and the
extent to which qualitative and quantitative
analyses are used, depending on the
complexity and particular circumstances of
the site, as well as the availability of
applicable or relevant and appropriate
requirements (ARARs) and other criteria,
advisories, and guidance." (Emphasis added).
See page 1-6.
Similarly, in "Risk Assessment Guidance for Superfund,
Volume II, Environmental Evaluation Manual," March 1989
(EPA, 1989b), EPA advises at page 10 that "[t]he
nature, extent, and level of detail of the ecological
assessment will be determined according to the phases
of the remedial process, the specific study objectives,
and the characteristics of the site and its
contaminants."
2.1.3 Additional Comment under B.I.: The commentor states
that paragraph 35 of the AOC requires Region 10 to
provide Respondents with "two or more baseline risk
assessment memoranda prior to the Respondents'
initiation of the Feasibility Study Report" and to
issue a baseline risk assessment report during site
characterization. The commentor goes on to state that
the "Administrative Record for the Site, however,
confirms that no baseline risk assessment memoranda
were provided to Respondents prior to initiation of the
Source^Area Containment ("SAC") Feasibility Study
report. Moreover, Region 10 has not yet issued a
baseline risk assessment report."
Response: Section IX of the AOC, entitled "EPA's
Baseline Risk Assessment," establishes that EPA will
perform the baseline risk assessment, and provides some
description of how EPA will provide information to the
AOC Respondents for purposes of performing the
D-20
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feasibility study report. Paragraph 35 of the AOC
states that EPA will provide sufficient information
concerning baseline risks such that the Respondents can
begin drafting the feasibility study report. EPA has
prepared a streamlined baseline risk assessment for the
source area of the Tulalip Landfill Site. In addition,
a comprehensive baseline risk assessment for the entire
site is expected to be completed in the summer of 1996.
The commentor misconstrues Paragraph 35 as requiring a
"baseline risk assessment" for the Source Area
Containment Feasibility Study (SAC-FS). Moreover, the
commentor narrowly interprets the AOC provisions for
risk assessments used at this Site by failing to
recognize the two-phased approach that was agreed upon
by EPA and the AOC Respondents. In addition, the
commentor is incorrect in stating that EPA is
"required" to provide the memoranda identified in
Paragraph 35.a. of the AOC before a feasibility study
is completed.
Paragraph 35.a. of the AOC states that. EPA will provide
"sufficient information concerning the baseline risk
such that the Respondents can begin drafting the
feasibility study report." There is no requirement
that EPA prepare a baseline risk assessment "prior to"
initiation of the feasibility study, as the commentor
writes. EPA provided the AOC Respondents the draft
Remedial Action Objectives for the SAC-FS based on data
gathered at the site and reported by the Respondents
during site characterization. The demonstrated
exceedances of comparison numbers showed sufficient
threats existed at the site to warrant development of
source area containment alternatives. Information
showing the threats at the site due to exceedances of
established federal and state environmental criteria,
standards, and risk-based concentrations provides an
adequate basis to develop and evaluate remedial
alternatives to address the environmental problems by
attaining those existing requirements. Therefore, EPA
believes that the site data submitted by the AOC
Respondents showed the need for~a response action to
contain the landfill wastes, and the Remedial Action
Objectives (RAOs) that EPA identified provided
sufficient information for the AOC Respondents to
prepare the SAC-FS.
The commentor's criticism of EPA for failing to
complete the "baseline risk assessment" prior to
completion of the SAC-FS fails to consider the phased
approach that EPA and the AOC Respondents agreed to
undertake at the Site. Paragraph 27 of the AOC and the
RI/FS Work Plan attached to the AOC clearly specify
D-21
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that EPA and the Respondents agreed upon a two-phased
approach for evaluating site conditions and possible
response actions. Both EPA and the AOC Respondents
recognized that the first phase was to evaluate
alternatives for the presumptive remedy of containment.
In the first phase, the Respondents agreed to complete
the Remedial Investigation for the entire site, and to
submit a focused feasibility study for the landfill
source area (referred to in Paragraph 27.g. as the
"Source Area Containment Feasibility Study"). The
second phase, described in Paragraph 27.h. of the AOC,
involves preparation of a feasibility study called the
"Site Feasibility Study" for the entire site, including
areas surrounding the source area. The Site
Feasibility Study required under the AOC clearly
contemplates that it will be prepared after the
Remedial Investigation Report had been completed and
after EPA selects the source area containment remedy.
Paragraph 27.h. states that the AOC Respondents shall
prepare a Site Feasibility Study that "incorporates the
Remedial Investigation by reference as approved by EPA,
and considers the Source Area Containment Presumptive
Remedy approved by EPA" (emphasis added). Therefore,
the two-phase RI/FS approach to which the AOC
Respondents and EPA agreed contemplates that the second
phase, full Site Feasibility Study will incorporate the
results of the first phase, which identified a source
area containment remedy. Paragraph 27.h. of the AOC
clarifies that both EPA and the Respondents recognized
that EPA would choose a source area containment remedy
prior to the initiation of the Site Feasibility Study.
In other words, work under the AOC was designed so that
EPA would prepare two risk assessments for the
potential response actions at the Site: one for the
source area containment remedy, and a second for the
off-source area.
EPA prepared the Streamlined Risk Assessment to
characterize current and potential threats to human
health and the environment that may be posed by
contaminants. The results from the Streamlined Risk
Assessment indicate that action is appropriate to
achieve significant risk reduction quickly. The
comprehensive baseline risk assessment for the off-
source area that EPA will prepare, and which is
contemplated by Paragraph 35.b. of the AOC, will
support the "Site Feasibility Study" required under
Paragraph 27.h. of the AOC, which has not yet been
initiated by the AOC Respondents. EPA has begun to
prepare the comprehensive baseline risk assessment and
will provide information from that effort when EPA
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directs the AOC Respondents to develop and submit the
Site Feasibility Study pursuant to the terms of the
AOC.
The commentor also is incorrect in asserting that
Paragraph 35 of the AOC "requires" EPA to provide the
memoranda that are described. Paragraph 35.a. of the
AOC states that this information "will normally be
provided in the form of two or more" memoranda, stating
one memorandum will "generally" include certain
information. The text of Paragraph 35.a. provides only
guidance as to how EPA will prepare the risk
assessment, and the terms of the AOC do not mandate
either the number or content of the memoranda. In
fact, EPA did provide the AOC Respondents an
opportunity to comment on the Interim Remedy Risk
Assessment, which contains all of the types of
information described in Paragraph 35.a. EPA intends
generally to follow the procedures described in
Paragraph 35 as it prepares the comprehensive baseline
risk assessment to support the Site Feasibility Study
and selection of a final remedy for the site in
addition to the source area containment .remedy.
2.2 Comment: "B.2. Region 10's Screening-Level Risk
Assessment for the Tulalip Landfill is Not the Baseline
Risk Assessment Required by CERCLA, the NCP and the
AOC." [2] [3]
Response: The Streamlined Risk Assessment developed
for the Source Area of the Tulalip Landfill meets all
statutory and regulatory requirements, as well as the
requirements set out in the RI/FS AOC (See Response to
Comment Section 2.1). Neither CERCLA, the NCP, nor the
general risk assessment guidances dictate a single
approach for conducting a risk assessment for all types
of Superfund sites. The nature of the risk assessment
is dependant on the scope and complexity of the site
problem to be addressed.
The risk assessment for the on-source area of the
Tulalip Landfill was initially referred to as a
"screening level" risk assessment. However, that term
has proven to be misleading. In general, a "screening
level" assessment is an evaluation of whether or not
there are exceedences of "screening criteria" that have
been selected for a particular site to determine if
further study is warranted. A streamlined risk
assessment under the presumptive remedy approach, on
the other hand, compares site data to established human
health and environmental criteria, standards, and risk-
based concentrations in order to support EPA decision-
• D-23
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making regarding the need for early or interim remedial
action to protect human health and the environment at a
given site. Thus, in order to avoid confusion in the
future, the risk assessment that was prepared for the
source area of the Tulalip Landfill is called the
Streamlined Risk Assessment.
In selecting the interim remedy, EPA has correctly
interpreted and followed the EPA Presumptive Remedy
guidance. The guidance clearly provides for selection
of an interim containment action based on the results
of a streamlined baseline risk assessment. The "Final
Tulalip Landfill Risk Assessment for Interim Remedial
Action" (the "Streamlined Risk Assessment") meets the
requirements of a streamlined baseline risk assessment
prescribed in EPA's presumptive remedy guidance.
The EPA guidance document entitled "Streamlining the
RI/FS for CERCLA Municipal Landfill Sites ("RI/FS
Streamlining Guidance", OSWER Directive No. 9355.3-
11FS, December 1990), explains the basic requirements
for streamlining the baseline risk assessment which
will support an early decision on a presumptive remedy.
Page 3 states:
"The purpose of the baseline risk assessment
is to determine whether a site poses risks to
human health and the environment that are
significant enough to warrant remedial
action. Because options for remedial action
at municipal landfill sites are limited, it
may-be possible to streamline or limit the
scope of the baseline risk assessment by:
1. Using the conceptual site model and RI-
generated data, to perform a qualitative
risk assessment that identifies
contaminants of concern in the affected
media, their concentrations, and their
hazardous properties which may pose a
risk through the routes of exposure."
The Streamlined Risk Assessment performed at the
Tulalip Landfill fully follows this guidance. Two
conceptual site models have been prepared: one for
Human Health Risks (Figure 5-5 of the interim ROD), and
one for Ecological Risks (Figure 5-6 of the interim
ROD) . The Streamlined Risk Assessment is a qualitative
risk assessment that identifies contaminants of concern
in the affected media (summarized in Tables 5-1, 6-1,
and 6-3 of the interim ROD). The interim ROD
identifies contaminant concentrations in Tables 6-2, 6-
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4, and 6-5, and Figures 6-1 and 6-2. The streamlined
Risk Assessment provides information on toxicity of
chemicals'that were found. Appendices A and B of the
streamlined Risk Assessment provides information on how
the standards and criteria were developed, against
which the site data were compared, and why an
exceedance of particular standards and criteria
represents a potential threat to the ecosystem.
Page 3 of the RI/FS Streamlining Guidance states that:
"2. Identifying all pathways that are an
obvious threat to human health or the
environment (see Figure 1) by comparing
RI-derived contaminant concentration
levels to standards that are potential
chemical-specific ARARs for the action.
These may include: (1) Non-zero MCLGs
and MCLs for groundwater and leachate
and (2) State air quality standards for
landfill gases.
When potential ARARs do not exist for a
specific contaminant, risk-based
chemical concentrations should be used."
Potential chemical-specific ARARs, including standards
and risk-based criteria, were used in the Risk
Assessment. For the human health evaluation, they are
listed in Table 6-1 of the interim ROD; those for the
ecological evaluation are listed in Table 6-3. The
potential chemical-specific ARARs, ..standards, and
criteria were taken from a number of different sources,
which are listed in the footnotes in the tables.
Sample results from the Tulalip Landfill Site that
exceeded these potential ARARs and criteria are
summarized in Tables 6-2, 6-4, and 6-5 of the interim
ROD. Tables 6-2, 6-4, and 6-5 show that Tulalip
Landfill site-specific sample results indicate 1367
exceedances of potential chemical-specific ARARS,
standards and risk-based criteria in various media.
Page 3 of the RI/FS Streamlining Guidance states that:
"3. Where established standards for one or
more contaminants in a given medium are
clearly exceeded, the basis for taking
remedial action is warranted (i.e.,
quantitative assessments that consider
all chemicals, their potential additive
effects, or additivity of multiple
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exposure pathways are not necessary to
initiate remedial action)."
In accordance with this guidance, EPA concludes that an
interim remedial action is warranted for the following
media, for which more than one exceedance is documented
in the interim ROD, Tables 6-2, 6-4 & 6-5:
Medium
Leachate
discharging from
the perimeter
landfill berm
Surface soil
Zone 2 ground
water4
Subsurface soil
Surface sediment
Surface water
Leachate seep
SP-016
Subsurface sediment
Number of
Exceedances3
510
414
160
113
94
26
26
24
Number of
Contaminants
41
26
16s
18
8
9
9
3
Based on this table, it is apparent that Site data
exceed comparison numbers, which include potential
ARARs, standards, criteria, and risk-based chemical
concentrations, for at least 1 contaminant for all of
j5 Includes exceedences of both total metals and filtered metals samples.
4 These results for Zone 2 ground water do not factor in dilution due to
tidal mixing between ground water wells and the ground water/surface water
interface.
5 Groundwater modeling results indicate that some of these contaminants
are unlikely to meet Ambient Water Quality Criteria standards at the ground
water/slough interface after taking into account potential dilution between
the wells and the ground water/slough interface.
6 Leachate seep SP-01 is unique among the leachate seeps sampled during
the RI because it is located on the landfill surface.
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the above media.7 In fact, for most media there are a
significant number of exceedences. Therefore, EPA has
concluded.that the basis for taking early, interim
remedial action is satisfied. In accordance with the
RI/FS Streamlining Guidance, the streamlined Risk
Assessment is not required to provide "quantitative
assessments that consider all chemicals, their
potential additive effects, or additivity of multiple
exposure pathways ... to initiate remedial action."
See OSWER Dir. No. 9355-11FS, at p. 3. The RI/FS
Streamlining Guidance expressly states that
quantitative assessments are not necessary to justify
remedial action where there is a clear exceedance of
established standards.
As shown in the table above, the streamlined Risk
Assessment clearly documents numerous instances where
site-specific data exceed potential chemical-specific
ARARs and standards, therefore EPA concludes that a
more thorough risk assessment is not necessary prior to
initiating an interim remedial action. The RI/FS
Streamlining Guidance goes on to state:
"This streamlined approach may facilitate
early action on the most obvious landfill
problems groundwater and leachate, landfill
gas, and the landfill contents---while
analysis continues on other problems such as
affected wetlands and stream sediments." Id.
This is precisely the approach that EPA has taken at
Tulalip Landfill. The RI/FS AOC and Work Plan have
been structured to enable early action on the source
area of the landfill, while analysis of other problems
continues. EPA and the Respondents are currently
proceeding on a separate track from this interim
remedial action to continue evaluating alternatives for
cleaning up the off-source wetlands and tidal channels
in an off-source Feasibility Study, and to produce a
comprehensive baseline risk assessment for the off-
source areas of the landfill.
EPA has based its decision to proceed with an interim
containment remedy based on numerous exceedances of
risk-based criteria in various media associated with
7 There were also exceedences of Zone 1 ground water, but Zone 1 ground
water was not included in the above list because exposure to Zone 1 ground
water would most likely occur through exposure to either the leachate seeps or
Zone 2 ground water entering the sloughs. The leachate seep and Zone 2 ground
water pathways are already captured in the above list.
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the landfill, including leachate, groundwater, pooled
surface water on the landfill, and off-source sediments
and soils'. EPA has begun work on the site
comprehensive baseline risk assessment, in accordance
with the presumptive remedy guidance, which may be
completed in the summer of 1996.
Presumptive remedy guidance makes no mention of the
need to collect surface data, although it recommends
the collection of many other types of data. A recent
EPA guidance document, called "Presumptive Remedies:
CERCLA Landfill Caps RI/FS Data Collection Guide"
(EPA/540/F-95/009, August 1995), describes the types of
data that should be gathered during the RI/FS.
Although this guidance was not available during the
scoping of the Tulalip RI/FS process, the RI/FS Work
Plan is generally consistent with this guidance:
"Since containment is the presumptive remedy
for MSWLFs (Municipal Solid Waste Landfills),
the Remedial Project Manager (RPM) can begin
making arrangements to collect landfill cap
design data as soon as a basis for remedial
action is established...." Id. at.l.
On page.5-1 of the RI/FS Work Plan for the Tulalip
Landfill Site (April 1993), EPA established that a
basis for remedial action existed based on site-
specific data available at that time. Page 5-1 states:
"The EPA has determined [Conducting Remedial
Investigation/Feasibility Studies for CERCLA
Municipal Landfill Sites (EPA/S40/P-91/001),
February 1991)] that remedial action for
source control at the Tulalip Landfill is
warranted because concentrations of several
contaminants in surface water at the landfill
(E&E 1988) exceed the established standards
of ambient water quality criteria (see
Section 3.1.2)."
EPA developed the RI/FS Work Plan, Field Sampling Plan,
and Quality Assurance Project Plan in accordance with
presumptive remedy guidance, and with considerable
input from the Respondents prior to finalizing these
documents. The Respondents, in signing the AOC, agreed
to follow the presumptive remedy approach for the
RI/FS, and agreed to collect site data in accordance
with the Work Plans they helped create. In a January
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11, 1993, letter,8 one of the Respondents transmitted
comments to EPA regarding the contents of a draft
version of the RI/FS Work Plan:
"Although we support the general concept of a
presumptive remedy, in this case it is
advisable to confirm environmental conditions
on and in the vicinity of the landfill prior
to remedy selection, and to base remedy
selection on performance standards."
This statement indicates the Respondents supported the
presumptive remedy approach for structuring the RI/FS,
and that in their view, site data must be gathered and
evaluated prior to selection of a remedy. Since the
time that statement was written, the RI has been
completed. Based on EPA's evaluation of the RI data,
it is clear that environmental conditions on and in the
vicinity of the landfill warrant remedial action.
The Respondents initiated a formal dispute process over
additional work they wanted to perform after they had
submitted the Source Area Containment Feasibility
Study. EPA determined that the additional work the
Respondents had requested was unnecessary and would not
provide significant additional information for a
decision on an interim containment remedy, and that the
Respondents' request to perform this additional work
was untimely. See, also. Response to Comment 2.9.1.
EPA was not willing to delay site cleanup to allow for
collection of this unnecessary data.
The Respondents' request to conduct additional sampling
for the purpose of evaluating any chemical
contamination on the landfill surface directly is
addressed by EPA guidance on presumptive remedies.
Page 5 of the "Presumptive Remedy for CERCLA Municipal
Landfill Sites" states:
"Streamlining the risk assessment of the
source area eliminates the need for sampling
and analysis to support the calculation of
current or potential future risk associated
with direct contact."
8 Letter dated January 11, 1993, from Leonard H. Sorrin of Bogle &
Gates, and Jeffrey S. Myers of Short, Cressman & Burgess, to William Glasser,
Remedial Project Manager, U.S. Environmental Protection Agency, Re: Comments
of the Seattle Disposal Company on the Draft Work Plan for the Tulalip
Landfill Superfund Site.
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The EPA Region 10 Deputy Regional Administrator's
determination on the Respondents' request to conduct
such sampling was wholly consistent with this guidance.
The Respondents' request for additional work to install
Zone 2 wells near the Zone 2/slough interface
contradicts their arguments during the Work Plan
scoping process. In a draft version of the Work Plan,
EPA initially planned to install the Zone 2 wells near
the Zone 2/slough interface. However, as part of
written comments on a draft version of the Work Plan,
the Respondents commented to EPA that the wells should
be moved back to the landfill perimeter bemv; a less
expensive approach. In response, EPA agreed to allow
installing the wells on the landfill berm. The final
Work Plan stated that the wells would be installed on
the berm, and during the RI/FS the Respondents
installed the wells on the berm and began sampling
them. They found exceedances of AWQC in the perimeter
berm wells, and they employed a groundwater modeling
approach to estimate what the concentrations would be
at the groundwater/slough interface in order to
evaluate whether State Ambient Water Quality Criteria
(AWQC) standards were likely to be exceeded at the
point where groundwater ente±s the slough.
The Respondents' modeling results indicated that,
taking into account the dilution of contaminants that
would be expected to occur between the perimeter wells
and the Zone 2/slough interface, exceedances of AWQC
were still likely at the Zone 2/slough interface for
some contaminants. After the SAC RI and FS reports had
been submitted, the Respondents initiated a formal
dispute process under the AOC and argued that EPA
should agree to the installation of additional wells at
the Zone 2/slough interface, which they had argued
against during scoping and prevailed. EPA believes
that the approach used in the RI/FS at the urging of
the Respondents, which included perimeter berm wells in
conjunction with groundwater modeling, is a sound and
reasonable technical basis for the purposes of EPA's
decision regarding an interim containment remedial
action.
2.3 Comment: "B.3. Region 10's Screening-Level Risk
Assessment Is Insufficient and Untimely For Purposes of
On-Source Remedy Determinations." [3]
2.3.1 .Additional Comments under B.3.: The commentor also
states that the "screening level risk assessment" is
insufficient in that it failed to use site-specific
data to satisfy the purposes of a baseline risk
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assessment. Additionally, the commentor states that
the risk assessment produced by EPA for the Site is
untimely in that it was issued after the SAC
Feasibility Report process was completed.
Response: The comments regarding the sufficiency of
the level of detail in the risk assessment and the
appropriateness of the timing of the risk assessment
are addressed above in the Response to Comment Section
2.1. In addition to the explanation provided in the
Response to Comment Section 2.1 regarding the level of
detail in the risk assessment, it is EPA's position
that the Tulalip Landfill is an appropriate site for a
streamlined risk assessment because sampling which had
been conducted at the site during the RI indicated
exceedances of water quality standards, criteria, and
risk-based concentrations. See EPA OSWER Directive No.
9355.0-49FS, "Presumptive Remedy for CERCLA Municipal
Landfill Sites," (EPA, 1993a), (Presumptive Remedy
Guidance), which states that a site generally will be
eligible for a streamlined risk assessment evaluation
if groundwater contaminant concentrations clearly
exceed chemical-specific standards or EPA's accepted
level of risk, or other conditions exist that provide a
clear justification for action. If no conditions are
shown to exist that provide clear justification for
action, a quantitative risk assessment that addresses
all exposure pathways will be necessary to determine
whether action is needed. See OSWER Dir. No. 9355.0-
49FS, p. 5., (EPA, 1993a).
Streamlined risk evaluation is appropriate at the
Tulalip Landfill because site investigation efforts,
including sampling done from 1993-4' by the Respondents
as part of the RI, indicate that landfill leachate
leaving the Site exceeds comparison numbers that are
considered protective of human health and the
environment, including water quality standards and
criteria, and risk-based concentrations for pesticides
such as DDT and aldrin, polychlorinated biphenyls
(PCBs), and heavy metals and other contaminants
including chromium, copper, lead, mercury, nickel,
zinc, ammonia, and heptachlor. The RI documents the
presence of hazardous substances contaminating soils,
sediments, surface water, and groundwater at the Site.
Hazardous substances found 'in surface soils at the Site
exceeded comparison numbers in one or more samples at
eight of the nine leachate soil grid locations. At six
of the leachate soil grid locations, subsurface soil
samples were collected. Hazardous substances found in
these subsurface soils exceeded comparison numbers in
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five of the six subsurface soil samples. Hazardous
substances found in leachate exceeded comparison
numbers a't least once in most of the eleven seeps that
were tested. Chemicals detected in Zone 1 groundwater
(which is generally located within the refuse layer of
the landfill) exceeding MCCs included the metals
copper, lead, nickel, and zinc, as well as ammonia,
cyanide, and the pesticide heptachlor epoxide. The
studies found that Zone 2 groundwater (which is
generally located below the refuse layer, except for
the former barge canals) was contaminated at levels
exceeding MCCs for the metals copper, lead, and nickel,
as well as cyanide and ammonia.
EPA's Presumptive Remedy Guidance recognizes that
almost every municipal landfill site has some
characteristics that may require additional study. See
OSWER Dir. No. 9355.0-49FS, p. 5. For example, such
characteristics may include leachate discharge to a
wetland or significant water run-off caused by drainage
problems. These migration pathways, as well as
groundwater contamination that has migrated away from
the source, generally will require characterization and
a more comprehensive risk assessment to determine
whether action is warranted beyond the source area and,
if so, the type of action that is appropriate. At the
Tulalip Landfill, leachate from the landfill flows
directly into sensitive, ecologically valuable wetlands
that surround the Site, and into sloughs connected with
the Snohomish River and Puget Sound. As a result, and
consistent with EPA's Presumptive Remedy Guidance, the
FS at the Site is being conducted in two phases in
order to address first the containment alternatives,
and secondly, the off-source alternatives.
2.3.2 Additional Comments under Comment B.3.: The commentor
concludes this comment section by reiterating that the
Risk Assessment is inadequate. The commentor cites
reasons for the apparent inadequacy, which are as
follows: (1) the Risk Assessment relies on overly
conservative criteria; (2) ignores extensive site data
that demonstrates risks are negligible; (3) fails to
consider background concentrations; (4) "screening
level criteria" were not applied at appropriate
locations/media; (5) use of 5 dated and
nonrepresentative 1988 ponded water samples to
characterize surface of a large surface; (6) denied
respondents requests for additional sampling; and (7)
the quality of data is questionable.
D-32
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Response: To avoid extensive duplication, the reader
is referred to the following specific responses. For:
(1) the Risk Assessment relies on overly conservative
criteria, see Responses to Comments 11.9 and 11.10; (2)
ignores extensive site data that demonstrates risks are
negligible, see Responses to Comments 2.10.2 and 11.6;
(3) fails to consider background concentrations, see
Responses to Comments 11.111 - 11.115; (4) "screening
level criteria" were not applied at appropriate
locations/media, see Responses to Comments 11.116 -
11.117; (5) use of 5 dated and nonrepresentative 1988
ponded water samples to characterize surface of a large
surface, see Responses to Comments 2.9..2, 2.9.3 and
11.7; (6) denied Respondents requests "for" additional
sampling, see Responses to Comments 2.9, 2.9.1, and
2.10.3; and (7) the quality of data is questionable,
see Responses to Comments 2.9.2 and 10.1-10.4.
2.4 Comment: . "B.4. EPA's Failure to Complete a Baseline
Risk Assessment For the Tulalip Landfill Is
Inconsistent With Its Approach at Other CERCLA Sites"
[3]
2.4.1 Additional Comments Under B.4.: The commentor
identifies other landfills in Washington and in other
states that the commentor believes are similar to the
Tulalip Landfill. The commentor states that EPA
properly utilized a baseline risk assessment process at
those sites to determine the need for remedial action.
The commentor concludes by saying that EPA acted
inappropriately at Tulalip by failing to conduct a
baseline risk assessment prior to selecting a remedy.
The following sites were identified by the commentor:
Whidbey Island Naval Air Station Operable Unit (OU)-2,
Area 2/3 and OU-4., Area 48/49, the Hamilton Island
Landfill, and the Everett Landfill (the previous three
sites are located in Washington state), the Old City of
York Landfill in Pennsylvania, the Suffolk City
Landfill in Virginia, the Broward County Landfill in
Florida and the Ordot Disposal Site in Guam.
Response: As explained in the Response to Comment 2.1,
above, EPA is not required by statute, regulation, or
guidance.to complete a comprehensive baseline risk
assessment prior to selecting and implementing an
interim remedy. The presumptive remedy process permits
EPA to conduct a streamlined baseline risk assessment
for the source area at the Tulalip Site. This approach
is also compliant with NCP and CERCLA requirements. In
addition, EPA is preparing a comprehensive baseline
risk assessment for the entire Tulalip Landfill site,
which is expected to be completed in the summer of
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1996. The comprehensive baseline risk assessment will
evaluate the need for further action for the off-source
areas of the site.
The Agency believes it is inappropriate and misleading
to compare sites because the facts which form the basis
for remedy decisions are unique to individual sites.
It is impossible to draw the conclusion that because a
certain approach was taken at one site, it is
appropriate to take that approach at an unrelated site.
The detailed decision-making process used at these
other sites in choosing a response action may not be
appropriate at the Tulalip Landfill. EPA Region 10
explains and supports in this interim ROD and the
Response to Comments its decision-making process,
including the use of a streamlined risk assessment, at
the Tulalip Landfill.
It is useful to note a fundamental difference between
the sites discussed by the commentor and the Tulalip
Landfill: none of the sites identified by the commentor
were evaluated or remediated (including No Action
determinations) pursuant to the presumptive remedy
process. At some sites the lead regulatory agency (in
some cases a state agency) and the potentially
responsible parties entered into contractual agreements
for investigative work or started investigative.work
before the presumptive remedy approach was developed
and consequently did not use the presumptive remedy
approach to structure the RI/FS and the remedy
selection process at those sites.
Sites which are located outside the state of Washington
may not be "similar" to the Tulalip Landfill because
they are subject to and must comply with different
state ARARs. Landfill sites located on military bases
may have very unique characteristics with regard to the
types of wastes disposed (e.g., munitions), and
therefore are also not "similar" to the Tulalip
Landfill.
While the commentor identifies certain of the operable
units (OU-3 and OU-4) at the Whidbey Island Naval Air
Station as examples, EPA notes that the commentor
failed to mention the operable unit #1 at Whidbey
Island. At OU #1, the final ROD called for a low
permeability landfill cover which meets the
requirements of the current state of Washington Minimal
Functional Standards (MFS) for landfill closure.
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2.5 Comment: "B.5. Region 10's Contention That a
Screening-.Level Risk Assessment Is Sufficient to
Support an 'Interim Remedial Action' Costing In Excess
of $40 Million Is Inconsistent With the NCP and EPA
Guidance." [3] [8]
Response: The commentor's statement that the selected
interim alternative costs $40 million is in error.
EPA's estimated cost of the estimated interim remedy,
Alternative 4c, Geosynthetic Cover with Passive
Drainage, is $25.1 million9. This cost, estimate
includes construction costs and operation and
maintenance (O&M) costs, calculated over a 30-year time
period using a 5% discount rate.10 EPA notes that O&M
may be required for more than 30 years.
The commentor may be confused by statements EPA made to
the AOC Respondents during the course of the de minimis
settlement discussions that the total site costs were
estimated at $40 million. The $40 million figure
represents the $25.1 million cost of the interim
remedy, plus EPA's past costs associated with the
Tulalip Landfill site, plus costs incurred by the
Respondents during the RI/FS, plus certain contingent
costs.
Selection of a containment alternative such as
Alternative 4c as an early/interim remedial action, is
consistent with CERCLA, the NCP, and EPA guidance on
presumptive remedies. Alternative 4c is considered an
early remedial action because it may not be the only
on-source or off-source action taken at the Site.
Potential additional containment actions for the source
area, if necessary, in the final ROD for the Site could
include things such as a groundwater treatment system,
installation of a perimeter leachate collection and
treatment system, if post-cover construction monitoring
shows that the cover is not adequately reducing
discharges of hazardous substances from the Site.
9 The Respondents' cost estimate for this alternative, which does not
account for the possibility that a landfill gas treatment system may be
required, is $22.4 million.
10 EPA considers actual remedial costs to fall within-+50% to -30% of the
cost estimate. In general, more detailed cost estimates are developed after
the ROD is issued, during detailed design stages.
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2.5.1 Additional Comment Under B.5.: The commentor claims
that Region 10 did not respond to technical comments on
the draft.risk assessment.
Response: EPA's August 4, 1995, letter to the
Respondents, which transmitted the final streamlined
risk assessment for the Interim Remedial Action,
states, in part:
"Please find enclosed the Final Risk
Assessment for Interim Remedial Action...The
draft was revised, in part to address those
of your comments that EPA agrees are
appropriately addressed in this document.
EPA intends to provide written responses to
your other comments (those with which we did
not agree are appropriately addressed in this
document) in the Responsiveness Summary that
EPA will prepare at the conclusion of the
public comment period for.the Proposed Plan
for Interim Remedial Action."
In accordance with the August 4th letter, this
Responsiveness Summary addresses all of the
Respondents' comments on the draft Streamlined Risk
Assessment for interim remedial action. See, also.
Response to Comments 11.6, 11.18 and 11.88.
2.5.2 Additional Comment Under B.5.: The commentor asserts
that "the Presumptive Remedy Guidance limits use of a
streamlined risk evaluation to those circumstances
where a public health risk is manifest because
chemical-specific groundwater standards are clearly
exceeded."
Response: EPA has explained in Response to Comment
Section 2.1, above, why the preparation of a
comprehensive baseline risk assessment at this Site in
support of this interim remedial action is neither
necessary nor appropriate. Further, EPA's Presumptive
Remedy Guidance identifies two situations where a
comprehensive baseline risk evaluation is not
necessary:
"As a matter of policy, for the source area
of municipal landfills, a quantitative risk
assessment that considers all chemicals,
their potential additive effects, etc., is
not necessary to establish a basis for action
if groundwater data are available to
demonstrate that contaminants clearly exceed
established standards or if other conditions
D-36
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exist that provide a clear justification for
action." (emphasis in original) See EPA's
"Presumptive Remedy for CERCLA Municipal
Landfill Sites", OSWER Directive No. 9355.0-
49FS, September 1993, p. 5, (EPA, 1993a).
The Tulalip Landfill site satisfies both of these
situations. This guidance recommends only that
exceedances of "groundwater standards1-1 be demonstrated,
or that "other conditions exist" which justify action,
in order to implement a streamlined or qualitative risk
assessment on the source area of a landfill rather than
a quantitative, or comprehensive risk assessment.
Contrary to the commentor's assertion, EPA's guidance
does not limit the use of streamlined risk assessments
to those situations where health-based drinking water
standards are exceeded. The use of a streamlined risk
assessment is, consistent with this guidance,
particularly appropriate at the Tulalip Landfill
because groundwater which has been shown to be
contaminated at levels that exceed Washington State
ambient water quality standards discharges directly
from the landfill into surface waters. EPA disagrees
with the commentor's narrow interpretation of the
Presumptive Remedy Guidance that the term "standards"
refers only to groundwater standards.
To further emphasize the appropriateness of using a
streamlined risk assessment to implement an early
remedial action, EPA notes that the Respondents have
recognized that conditions at the Tulalip Landfill
warranted an expedited approach for implementation of
response action. The commentor, on behalf of his
clients Josie Razore and John Banchero, sought an
emergency preliminary injunction from the U.S. Court of
Appeals for the Ninth Circuit, requesting that the
Court take immediate measures to stop the generation of
the leachate from the landfill. The PRPs cited expert
testimony that leachate is discharging from the Tulalip
Landfill at levels exceeding water quality criteria
such that water quality in the surface waters adjacent
to the landfill will "fall below the level that will
sustain fish and other aquatic life in the waters
surrounding the Landfill." See July 26, 1995, letter
from Richard McAllister, Assistant Regional Counsel,
EPA Region 10, to Wm. Roger Truitt of Piper & Marbury,
(McAllister, 1995) (this letter can be found in the AR
for the Tulalip Landfill Site).
EPA has proceeded with a streamlined risk evaluation to
support selection of an early/interim remedy for the
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landfill source area consistent with EPA's Presumptive
Remedy Guidance.
EPA is currently developing a comprehensive baseline
risk assessment (comprehensive baseline risk
assessment) for the Site. EPA expects the
comprehensive baseline risk assessment will be
completed in the summer of 1996. The purpose of the
comprehensive baseline risk assessment will be to
evaluate whether additional cleanup measures should be
undertaken in the off-source areas to address
contamination that has migrated to these areas from the
landfill. A comprehensive baseline risk assessment is
not necessary to develop interim alternatives for the
source area of the landfill, nor would it allow
development and evaluation of less expensive
containment alternatives for the source area.
Selection of an interim remedial action for the source
area is fully supported by the completed Streamlined
Risk Assessment (RA) for Interim Remedial Action, which
documents numerous exceedances of comparison numbers
that are considered protective of human health and the
environment. Based on the results of the RI/FS, the
streamlined RA, the evaluation of the alternatives in
the Proposed Plan against the nine criteria, and public
comments, EPA has selected Alternative 4c as an interim
remedial action because it provides the best balance of
the nine criteria and is cost effective. Selection of
this alternative as an early/interim action is fully
consistent with CERCLA, the NCP, and EPA guidance.
Completion of a comprehensive baseline risk assessment
is not required to make this interim decision.
Contrary to the commentor's assertion, EPA's
Presumptive Remedy Guidance for Municipal Landfills
provides for EPA to take early and interim response
actions, including conducting a streamlined risk
assessment, in situations other than those in which
chemical-specific groundwater standards have been
clearly exceeded. The Presumptive Remedy guidance
refers to previously-issued EPA guidances, in
particular a February 1991 guidance (OSWER Dir. No.
9355.3-11) entitled "Conducting Remedial
Investigations/ Feasibility Studies for CERCLA
Municipal Landfill Sites", (EPA, 1991) which in turn
references another EPA guidance document issued in
September 1990, entitled "Streamlining the RI/FS for
CERCLA Municipal Landfill Sites" (EPA, 1990a). The
"Streamlining the RI/FS" guidance states as follows:
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"When established standards for one or more
contaminants in a given medium are clearly
exceeded, the basis for taking remedial
action is warranted (i.e., quantitative risk
assessments that consider all chemicals,
their potential additive effects, or
additivity of multiple pathways are not
necessary to initiate remedial action.)" See
"Streamlining the RI/FS for CERCLA Municipal
Landfill Sites," OSWER Directive No. 9355.3-
11FS, (September 1990), p. 3, (EPA, 1995a).
Clearly, this guidance envisions EPA performing
streamlined risk assessments when standards in media
other than groundwater are exceeded. In addition, it
defies common sense to read the Presumptive Remedy
Guidance as narrowly as the commentor suggests. CERCLA
contains broad powers which allow the President
(through the EPA) to address releases of hazardous
substances that potentially or actually threaten human
health and the environment. The commentor's narrow
reading of CERCLA and the Presumptive Remedy Guidance
would tie EPA's hands and prevent EPA from acting
quickly under CERCLA and the Presumptive Remedy
Guidance to address releases to media other than
groundwater. Clearly, in order to be able to protect
human health and the environment, EPA must be able to
address releases to all media, not just releases to
groundwater, even if the action being taken was
developed using the Presumptive Remedy Guidance.
2.5.3 Additional Comment Under B.5.: The commentor was
concerned that "Region 10's analysis failed to consider
another NCP program management principle, specifically:
site specific data needs, the evaluation of
alternatives, and the documentation of the selected
remedy should reflect the scope and complexity of the
site problems being addressed."
Response: On the contrary, EPA's approach at the
Tulalip Site appropriately considered and implemented
this NCP program management principle. As discussed
above, the Tulalip Site has been broken into two
phases: the first phase will address the source area of
the landfill, and the second phase will address the
off-source areas of the site. This phased approach was
used in order to speed up the remedial process and
tailor remedial decision-making to more specific areas
of the site.
The June 14, 1995, memorandum from EPA's Office of
General Counsel entitled "Presumptive Remedies and NCP
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Compliance" was issued in order to explain the
relationship of EPA's presumptive remedies initiative
for CERCLA sites to the requirements of the NCP, and
specifically addresses consistency of the presumptive
remedy approach with NCP program management principles
such as site specific data needs and evaluation of
alternatives. The OGC memorandum supports the
presumptive remedy approach taken at the Tulalip
Landfill site in selecting a remedy:
"The use of presumptive remedies as part of
the remedy selection process at appropriate
sites is consistent with the program
management principle in 40 C.F.R.
§ 300.430(a)(1)(ii)(C). That is, using a
remedy found to be generally appropriate for
a class of sites narrows the scope and
complexity of the remaining issues that need
to be addressed on a site-specific basis. In
other words, presumptive remedies speed up
the remedy selection process so that, once
site data has been gathered, EPA can begin
action more quickly." Id. at p. 4.
* * *
"The identification of presumptive remedies
serves, in effect, to carry out the screening
and detailed analysis steps in a generic
manner that minimizes the need to perform
those steps at a site-specific level. In
developing a presumptive remedy for a certain
type of site, or sites containing a certain
type of waste, EPA evaluates technologies
that are commonly considered for a certain
type of site and identifies one or more
technologies as being generally most
appropriate..."
"Where circumstances at a site correspond to
those for which the presumptive remedy was
identified as generally suitable, the generic
analysis of the NCP remedy selection criteria
that was performed in identifying the
presumptive remedy should be adequate, and
need not be repeated site-specifically. ...
In effect, as will be discussed in more
detail below, the materials prepared in the
generic analysis will substitute for a
broader FS. Similarly, the technology
identification and screening steps done for
the generic presumptive remedy analysis will
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serve as the technology and screening steps
for the site at hand." Id. at p. 6.
EPA's intent in using presumptive remedies is to meet
NCP requirements in a more efficient and streamlined
manner. Presumptive remedies were designed as part of
the Superfund Accelerated Cleanup Model (SACM), which
in turn is an EPA program management principle designed
•in response to PRP complaints that the remedy selection
process was too lengthy and expensive, and that EPA
mandated excessive study prior to the selection of
alternatives. In designing presumptive remedies, EPA
screened out, up-front, certain alternatives which
would be inappropriate for particular types of sites.
At the Tulalip Landfill Site, EPA followed the NCP
requirements by using a presumptive remedy analysis as
the technology and screening steps for the Site. In
fact, EPA went beyond the requirements for presumptive
remedies at this Site by evaluating alternatives, such
as Alternatives 2b and 2b(ii), which do not fall within
the traditionally accepted presumptive remedies for
landfills. In addition, while 2b and 2b(ii) include
the concept of leachate collection, the commentor has
not identified sites where this design has been
successfully employed in a similar environment as
Tulalip.
2.5.4 Additional Comment under B.5.: The commentor also
states that EPA in the NCP does not discuss when a
screening-level risk assessment can be substituted for
a baseline risk assessment.
Response: As discussed above in Response to Comment
2.1.2, the NCP recognizes that different sites require
varying levels of analysis and study prior to the
selection of a response action, depending on the
approach selected for the site. Specifically, with
respect to the scope of the risk assessment, the
"Presumptive Remedy for CERCLA Municipal Landfill
Sites" (EPA, 1993a) states as follows:
"The municipal landfill manual states that a
streamlined or limited baseline risk
assessment will be sufficient to initiate
response action on the most obvious problems
at a municipal landfill (e.g. groundwater,
leachate, landfill contents, and landfill
gas). One method for establishing risk using
a streamlined approach is to compare
contaminant concentration levels (if
available) to standards that are potential
chemical-specific applicable or relevant and
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appropriate requirements (ARARs) for the
action. The manual states that where
established standards for one or more
contaminants in a given medium are clearly
exceeded, remedial action generally is
warranted." See OSWER Dir. No. 9355.0-49FS,
Sept. 1993, at p. 4, (EPA, 1993a).
This guidance also addresses the issue of whether a
qualitative as opposed to quantitative risk assessment
is necessary for an interim remedy at a municipal
landfill:
"As a matter of policy, for the source area
of municipal landfills, a quantitative risk
assessment that considers all chemicals,
their potential additive effects, etc., is
not necessary to establish a basis for action
if ground-water data are available to
demonstrate that contaminants clearly exceed
established standards or if other conditions
exist that provide a clear justification for
action." (Emphasis in original).
"Almost every municipal landfill site has
some characteristic that may require
additional study, such as leachate discharge
to a wetland or significant surface water
run-off caused by drainage problems. These
migration pathways, as well as ground-water
contamination that has migrated away from the
source, generally will require
characterization and a more comprehensive
risk assessment to determine whether action
is warranted beyond the source area and, if
so, the type of action that is appropriate."
(Emphasis added) Id. at p. 5.
EPA has followed this recommended approach in the
Streamlined Risk Assessment. The primary conclusion of
the Streamlined Risk Assessment is that actual
concentrations detected in leachate being released from
the landfill significantly exceed comparison numbers
that are considered protective of human health and the
environment, including specific health-based and
ecological standards, criteria, and risk-based
concentrations. The NCP's "bias for action" principle
leads EPA to implement a response action that will
expeditiously reduce this harm rather than wait for a
full site-wide characterization of all problems caused
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by the landfill and an assessment (which are still
under development in order to determine whether
additional cleanup actions are necessary for the
Tulalip Landfill site). Nothing in the NCP, the
preamble to the NCP, or pertinent guidance requires EPA
to wait until more studies are completed, or until a
comprehensive, quantitative risk assessment is
performed, to go forward with its plan for a
containment remedy at the Tulalip Landfill site to
reduce discharges of leachate. See, also. Response to
Comment 2.2.
2.5.5 Additional Comment Under B.5.: The commentor states
that Region 10's reliance on the Presumptive Remedy
Guidance to streamline the risk assessment is
"misplaced" because promulgated regulations such as the
NCP "control" over unilaterally-issued Agency guidance
when the regulation and the guidance "conflict", and
because the use of a streamlined risk assessment is
limited to only those sites where a public health risk
is manifest and chemical-specific groundwater standards
are clearly exceeded.
Response: The commentor claims that the NCP and EPA
guidance.documents conflict with each other in that the
commentor states that the NCP always requires a site-
specific baseline risk assessment to be completed
before a remedial action is selected. EPA disagrees
with the commentor's interpretation of the NCP
requirements, and EPA disagrees with the commentor's
belief that there is a conflict between the NCP and EPA
guidance. As EPA observed in its Response to Comment
Section 2.1, the NCP does not require a more
comprehensive risk assessment than the one EPA has
completed for the Tulalip source area in order to take
the type of action that EPA is selecting for the source
area of the Site. The NCP does require a balancing
process regarding if and when EPA chooses to take early
action at a site. This balancing process involves
weighing the need for prompt, early actions against the
need for definitive site characterization. The
preamble to the 1990 revisions to the NCP states:
"EPA expects to take early action at
sites where appropriate, and to
remediate sites in phases using operable
units as early actions to eliminate,
reduce or control the hazards posed by a
site or to expedite the completion of
total site cleanup. In deciding whether
to initiate early actions, EPA must
balance the desire to definitively
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characterize site risks and analyze
alternative remedial approaches for
addressing those threats in great detail
with the desire to implement protective
measures quickly. Consistent with
today's management principles, EPA
intends to perform this balancing with a
bias for initiating response actions
necessary or appropriate to eliminate,
reduce, or control hazards posed by a
site as early as possible" (underlining
added). 55 Fed. Reg, at 8704 (March 8,
1990).
The Streamlined Risk Assessment that EPA has completed
for the source area of the Site, along with the RI/FS
for the Site, reflect the nature and complexity of the
problem and the response alternatives considered. EPA,
in the Proposed Plan and this interim ROD, balanced the
need for action based on its evaluation of existing
data and the nature of the Site against the need to
develop more data as the basis of a more comprehensive
risk assessment. EPA.determined that the selected
containment remedy was appropriate given the risks
known to exist at the Site as evaluated in the
streamlined RA.
The preamble to the NCP and EPA guidance documents
provide more detailed information on how EPA suggests
risk assessments may be conducted at Superfund sites of
varying scope and complexity. A close examination of
these sources shows that the Streamlined Risk
Assessment is consistent with EPA's policy for sites of
similar scope and complexity to the Tulalip Landfill
Site and, does in fact, meet minimum requirements for
risk assessment:
"To implement an early action under the
remedial authority, an operable unit for
which an interim action is appropriate is
identified. Data sufficient to support the
interim action decision is extracted from the
ongoing RI/FS that is underway for the site
or final operable unit and an appropriate set
of alternatives is evaluated...A completed
baseline risk assessment generally will not
be available or necessary to justify interim
action."
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"Qualitative risk information should be organized
that demonstrates that the action is necessary to
stabilize the site, prevent further degradation,
or achieve significant risk reduction quickly."
See 55 Fed. Reg, at 8704 (March 8, 1990) (Emphasis
added).
EPA's "Risk Assessment Guidance For Superfund, Volume
1, Human Health Evaluation Manual (Part A)," December
1989 (EPA, 1989a), further elaborates on the principle
that varying levels of detail are required in risk
assessments, depending on the timing of the action to
be taken at a Site:
"Although risk information is fundamental to the
RI/FS and to the remedial response program in
general, Superfund site experience has led EPA to
balance the need for information with the need to
take action at sites quickly and to streamline the
remedial process. Revisions proposed to the NCP
in 1988 reflect EPA program management principles
intended to promote the efficiency and
effectiveness of the remedial response process.
Chief among these principles is a bias for
action." See page 1-1.
"Baseline risk assessments are site-specific
and therefore may vary in both detail and the
extent to which qualitative and quantitative
analyses are used, depending on the
complexity and particular circumstances of
the site, as well as the availability of
applicable or relevant and appropriate
requirements (ARARs) and other criteria,
advisories, and guidances." See page 1-6.
Similarly, in "Risk Assessment Guidance for Superfund,
Volume II, Environmental Evaluation Manual," March 1989
(EPA, 1989b), EPA advises at page 10 that: "The
nature, extent, and level of detail of the ecological
assessment will be determined according to the phases
of the remedial process, the specific study objectives,
and the characteristics of the site and its
contaminants."
Thus, it is clear that Region 10's selection of the
interim remedial action 'in the interim ROD is
consistent with both the NCP and EPA-issued guidance,
and that the NCP and the guidance documents do not
conflict with each other.
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Regarding the commentor's claims that the streamlined
risk assessment is limited to only those sites where a
public health risk is manifest and chemical-specific
groundwater standards are clearly exceeded, EPA refers
the commentor to the "Streamlining the RI/FS for CERCLA
Municipal Landfill Sites" (EPA, 1990a) and the
"Presumptive Remedy for CERCLA Municipal Landfill
Sites" (EPA, 1993a) guidance issued in September of
1990 and September of 1993. Both state that where
"established standards for one or more contaminants in
a given medium are clearly exceeded, the basis for
taking remedial action is warranted." Neither guidance
document stated that the "established standards" only
refers to chemical-specific groundwater standards.
Rather, the Presumptive Remedy Guidance uses an
exceedance of groundwater standards as one example of
when a presumptive remedy may be considered at
municipal landfill sites. In addition, footnote #3 in
the Presumptive Remedy Guidance states that if MCLs or
non-zero MCLGs are exceeded, a response action
generally is warranted. These are given as examples
and should not be read as limitations on the triggering
of a remedial action pursuant to the presumptive remedy
process. Groundwater standards are frequently given as
examples because groundwater for drinking water
purposes is often one of the media of concern at a
landfill. At the Tulalip Landfill, contaminated
groundwater is unlikely to impact drinking water
supplies, so EPA believes it would not be meaningful to
compare Site groundwater data to MCLs or non-zero
MCLGs, even though Site data does exceed these values
for some chemicals. However, EPA does believe it is
appropriate to compare Site data to state and federal
surface water standards and criteria, because the
Streamlined Risk Assessment and the RI show that
contaminated groundwater from the Site discharges
directly to surface waters at contaminant levels that
exceed the surface water standards and criteria. The
commentor did not submit a specific reference in his
comments supporting his claim that the use of
presumptive remedies is limited to only those sites
where there has been an exceedance of groundwater
standards.
The commentor goes on to state that the July 26, 1995,
letter from Richard McAllister of EPA to Wm. Roger
Truitt (McAllister, 1995) confused exceedances of AWQC
in the EPA ecological risk evaluation with the
Presumptive Remedy Guidance's streamlining trigger for
exceedances of health-based drinking water standards
during EPA's ecological evaluation in the streamlined
RA. Additionally, the commentor implies that because
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AWQC are not enforceable criteria, remedial action
cannot therefore be based on exceedances of those
criteria, and that remedial action can only be based on
enforceable drinking water standards. As EPA has
previously responded to the commentor, EPA in the
Streamlined Risk Assessment used comparison numbers
that are considered protective of human health and the
environment, including specific health-based and
ecological standards, criteria, and risk-based
concentrations, when it examined Site data to determine
whether there were human health and ecological risks at
the Tulalip Site. Thus, any exceedances of the
comparison numbers indicated to EPA that there may be a
risk associated with those exceedances which required
further discussion in the Streamlined Risk Assessment.
See also Response to Comment 11.9.
Contrary to the commentor's claim, EPA did not confuse
drinking water standards with AWQC in the development
of the Streamlined Risk Assessment. EPA believes that
it was consistent with CERCLA, the NCP and EPA guidance
when it used federal AWQC and state AWQ standards as
tools in development of comparison numbers in the
Streamlined Risk Assessment.
With regard to the issue of .whether federal AWQC can be
used to justify remedial action, EPA has determined in
the interim ROD that federal AWQC, along with the state
of Washington water quality standards for surface
water, are important chemical-specific relevant and
appropriate ARARs. The AWQC are specifically
identified as a potential ARAR in CERCLA Section
121(d)(2)(B), which states that federal water quality
criteria are to be attained "where relevant and
appropriate."11 In addition, AWQ standards that are
promulgated by the state of Washington and which are
enforceable, have been identified as ARARs that are
being exceeded under baseline conditions at the Tulalip
Landfill. The interim remedy selected for
implementation at the Tulalip Site must -satisfy all
ARARs identified in the interim ROD for the Site.
11 It should be noted that the commentor, in referring to Attachment 11
of his comments in support of his argument that federal "ambient water quality
criteria are not rules and have no regulatory impact," relies on a May 1,
1986, EPA guidance document. On October 17, 1986, Congress passed the SARA
amendments to CERCLA, in particular Section 121 of CERCLA, which specifically
states that federal water quality criteria may be "relevant and appropriate"
standards in CERCLA actions. Thus, referencing the May 1, 1986, EPA guidance
to support the idea that AWQC are not enforceable under CERCLA is not
appropriate.
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2.6 Comment: "E.G. Region 10's Screening-Level Risk
Assessment is Contrary to Congressional Directives and
"Common Sense" Superfund Administrative Reforms
Announced by EPA Headquarters." [3]
Response: The commentor discusses some of the
provisions in the U.S. Senate Committee on
Appropriations "Committee Report." According to the
commentor, the report states that EPA's cleanup budget
will be reduced, that Congress will give direction to
the Agency to focus its resources on the worse sites
first and to modify its risk assessment procedures.
While it is true that EPA's budget, including the
budget for the Superfund program, has been the subject
of debate, the Agency does not yet have a final budget
for this year. Nor has Congress produced any statutory
revisions to CERCLA that have progressed to the point
of approval in either the House or the Senate. Once a
revised CERCLA bill becomes law, the Agency will review
its requirements and make any appropriate changes in
the Superfund program. At this time, the Agency cannot
predict whether changes will need to be made in the way
the Agency implements the Superfund program in the
future and if those changes will have an effect on the
evaluation and implementation of remedial action at the
Tulalip Site. The Agency cannot base present decisions
and action on draft Congressional bills such as HR 2099
which have not become law. Also, the Agency at present
cannot make any predictions regarding the EPA budget
directives or anticipate what the final budget will be,
how monies will be allocated for what actions, or what
the provisions of a re-authorized CERCLA will be. As
such, EPA Region 10 will not make changes to the
Tulalip Site decision-making process until EPA
Headquarters has issued regulations or guidance on how
a newly re-authorized CERCLA statute will be
implemented and after the Region determines whether
these changes would affect the Tulalip Site. For the
present, the Region is lawfully and justifiably
proceeding with this interim remedial action based on
current laws, regulations, and policies. Further our
planned action at the Tulalip Landfill is fully
consistent with the Superfund Administrative Reforms
initiative announced by the Agency on October 4, 1995.
2.6.1 Additional Comment Under B.6.: The commentor notes
that the AR for this Site does not contain a health
assessment conducted by the ATSDR. In addition, the
commentor also notes that the Congressional Committee
Report directs EPA to only take action when an ATSDR
report indicates that a site poses a health hazard.
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The commentor also noted that EPA is implementing 20
new administrative reforms to the Superfund program.
The commentor cites one of the reforms as being the
establishment of national criteria to "reality test"
risk assessments conducted by the Superfund program.
The commentor goes on to conclude that the risk
assessment "must be withdrawn and a proper baseline
risk assessment using sound science, current land use
and reasonable exposure pathways and assumptions must
be performed for the Site."
Response: Region 10 will implement new reform
policies when the criteria and procedures are in place
to do so. The "national criteria" that the commentor
refers to in his comment will be incorporated into the
Tulalip Site if and when it is appropriate to do so.
This current action at the Tulalip Landfill is fully
consistent with EPA policy.
ATSDR completed a preliminary health assessment for the
Tulalip Landfill Site on June 2, 1993. That ATSDR
report did not identify that a health emergency existed
at the Tulalip Site. However, the ATSDR report was
based upon sampling data and Site information as it
existed at the time it was prepared. Since that time,
the RI conducted by the Respondents has shown numerous
exceedances of comparison numbers used in the
Streamlined Risk Assessment. These comparison numbers
are considered to be protective of human health and the
environment. The Region considered but did not rely
upon the information contained in the 1993 ATSDR report
when the Region made its interim remedial action
decision in the interim ROD for the Tulalip Landfill
Site. However, the Region has added the 1993 ATSDR
report to the AR for this Site as historical
information.
As mentioned above, EPA is unwilling to speculate how
any new CERCLA legislation or EPA funding legislation
will look in their final form. The Region cannot
implement the CERCLA program based upon draft
legislation. The Region must continue to implement the
CERCLA law as it is currently written, and as directed
by EPA guidance and policy. Therefore, the Region
disagrees with the commentor's statements that the
streamlined risk assessment for the Tulalip Site "must
be withdrawn" and that a comprehensive "baseline risk
assessment" must be performed before the Region can
proceed with this interim remedial action. A
comprehensive baseline risk assessment is currently
being developed for the Tulalip Landfill Site. EPA
expects the comprehensive baseline risk assessment may
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be.completed in the summer of 1996. The purpose of the
comprehensive baseline risk assessment is to evaluate
whether additional cleanup measures should be
undertaken in the off-source areas to address
contamination that has migrated to these areas from the
landfill. A comprehensive baseline risk assessment is
not necessary to develop interim alternatives for the
source area of the landfill, nor would it allow
development and evaluation of less expensive
containment alternatives for the source area.
2.7 Comment: "C. Region 10 Has Developed the Proposed
Plan in an Arbitrary, Capricious and Unlawful
Manner."12 [3]
2.7.1 Additional Comment under C.: The commentor suggests
that the Region failed to act impartially when it
selected a cap as part of this interim remedial action.
The commentor suggests that the Region had "pre-
ordained" that a cap would be the preferred alternative
in the Region's development of the Proposed Plan for
this interim action.
Response: Contrary to the commentor's assertions, the
Region did not "pre-ordain" that a landfill cap would
be the preferred alternative for containment of the
hazardous substances at the Tulalip Landfill. The
commentor cites a letter dated May 7, 1993., written by
the Region 10 Project Manager and sent to the Tulalip
Tribes of Washington, in which the commentor suggests
that the Region had "pre-ordained" that a cap would be
the preferred alternative. In that letter, Region 10's
Project Manager states:
"EPA, in consultation with the [Tulalip]
Tribe and the Bureau of Indian Affairs, has
determined that the "presumptive remedy" of
containment is appropriate for the Site. A
"presumptive remedy" means that we expect the
final remedy will in some manner contain the
landfill wastes through a cap and other
appropriate controls. In other words, the
RI/FS will not evaluate more expensive
'" The commentor listed his comments on page 15 of his October 25, 1995,
letter as being under subheading "B", while on page 3 of his letter, he also
lists those comments as being under subheading "B". The Region will treat the
comments from page 15 to page 29 as being under subheading "C," in order to
avoid confusion.
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remedial alternatives, such as to excavate,
treat or otherwise dispose of the waste
materials." (Emphasis added).
"The goal of the containment action will be
to attain quickly a cleanup that is
protective of human health and the
environment. A key component of the
containment remedy will be a cap that covers
the waste material that is buried at the
landfill. The purpose of a cap will be to
minimize leachate production by preventing
precipitation and surface water from coming
in direct contact with the landfill wastes."
The commentor misconstrues the statements made in that
letter. Contrary to the commentor's assertions, EPA
did not pre-select a landfill cover for Tulalip
Landfill prior to issuance of the interim ROD. EPA's
presumptive remedy guidance calls for "containment" as
the presumptive remedy. The guidance does not dictate
that the presumptive containment remedy shall, in every
case, consist of a landfill cover. However, the
guidance clearly recognizes that in the past, for most
municipal landfill-type sites, a low permeability
landfill cover was the selected remedy. In addition,
page 2 of the guidance document "Presumptive Remedy for
CERCLA Municipal Landfill Sites" (EPA, 1993a) states:
"Highlight 1 identifies the components of the
presumptive remedy. Response actions
selected for individual sites will include
only those components that are necessary,
based on site-specific conditions."
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Highlight 1: Components of
the Presumptive Remedy:
Source Containment
Landfill cap
Source Area ground-water
control to contain plume
Leachate collection and
treatment
Landfill gas collection and
treatment
Institutional controls to
supplement engineering
controls
Highlight 1 is reproduced verbatim from the guidance
document. Presumptive remedy guidance clearly
envisions a low permeability landfill cap as a
component of containment, and states that the RI/FS
should be streamlined to gather data necessary to
support construction of the presumptive remedy. Page 6
of this guidance document states: "[t]herefore, the
focus of the RI/FS can be shifted....to collecting data
to support design of the containment remedy." The
guidance also states that once EPA determines action is
necessary, State landfill closure requirements [i.e.,
the Washington State Minimum Functional Standards
codified at Chapter 173-304 of the Washington
Administrative Code (WAC)] which are ARARs and are more
stringent than federal standards must be either
attained or waived. EPA has determined that there is a
need for an interim remedial action at Tulalip, and
that the Chapter 173-304 standards have been identified
as an ARAR in the interim remedial action ROD, and
those standards call for the installation of a low
permeability cap on the landfill surface. See WAC 173-
304-460.(3) .
Another guidance document, entitled "Streamlining the
RI/FS for CERCLA Municipal Landfill Sites" (EPA,
1990a), states on page 4:
"The most practicable remedial alternative
for landfills is generally containment.
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Figure 3 is a simplified decision tree for
identifying the appropriate type of cap."
(Emphasis added).
This statement, and other statements throughout the
guidance documents on presumptive remedies and
municipal landfills, indicates that a streamlined
RI/FS, which is what was used at the Tulalip Site,
suggests a data collection approach that will provide
for early implementation of a containment remedy, which
generally will include a landfill cap.
EPA guidance calls for containment of landfill wastes,
not necessarily a landfill cap, as the presumptive
remedy for municipal landfills. The presumptive remedy
guidance does call out capping as an alternative that
should be considered as a containment alternative,
along with leachate, groundwater, and landfill gas
controls. Accordingly, the interim ROD evaluates
containment alternatives that do and do not include a
low permeability landfill cap. The following
alternatives from the ROD do not include a cap:
1 " No Action
2 Active Seep Interception
2b Leachate Collection with Discharge to
.^~.: Treatment Berm
2b(ii) Leachate Collection with Discharge to
POTW
3 Leachate Seep and Groundwater Collection
and Treatment
The following alternatives do include a cap:
4a Soil Cover with-Passive Drainage
4b Geosynthetic Cover with Active Drainage
4c Geosynthetic Cover with Passive Drainage
4d Composite Cover with Passive Drainage
5 Cover with Leachate Seep Control
6 Cover with Leachate Seep Control and
Zone 2 Groundwater Collection/Treatment
EPA devoted a substantial amount of resources, and
significantly delayed issuing the Proposed Plan for
Interim Remedial Action, to fully evaluate the
Respondents' proposed Alternative 2b. EPA received a
written proposal from the Respondents regarding
Alternative 2b on June 30, 1995, after the final Source
Area Containment Feasibility Study had been submitted
to EPA on May 5, 1995. Subsequent to the April meeting
with the Port of Seattle, EPA met with the Respondents
and the Tulalip Tribes and internally several times to
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discuss and evaluate Alternative 2b. In order to fully
evaluate the technical issues associated with
Alternative 2b, EPA delayed issuing the Proposed Plan
by at least a month. EPA's written technical
evaluation of Alternative 2b is in the form of a
Memorandum to The File by Eric Winiecki, dated August
4, 1995, (Winiecki, 1995d) which has been included in
the Administrative Record for this interim remedial
action. The memorandum includes technical analyses and
a revised cost estimate from EPA's technical
consultant, Roy F. Weston, Inc. Attached to the
memorandum are additional, written technical memoranda
from EPA technical staff based on their review of
Alternative 2b, including Catherine Massimino
(engineer), Glenn Bruck (hydrogeologist), Rene Fuentes
(hydrogeologist), Jay Vasconcelos (microbiologist), and
Donald Matheny (chemist).
The Respondents collected and analyzed data during the
RI/FS in accordance with the RI/FS Work Plan and the
RI/FS Field Sampling Plan, and the Quality Assurance
Project Plan (QAPP) which were attachments to the RI/FS
Administrative Order on Consent. The Respondents
actively participated in negotiating the contents of
these Plans over a 9-month "scoping" period, and EPA
made many changes to the draft Plans based on comments
from the Respondents.13 In accordance with EPA
guidance on presumptive remedy guidance, including
"Presumptive Remedy for CERCLA Municipal Landfill
Sites" (EPA, 1993a), the Plans were developed using a
streamlined approach to gather data to support early
implementation of a containment remedy at Tulalip
Landfill. The data collection described in these Plans
is consistent with EPA guidance on gathering data for
landfill sites and presumptive remedies, including
"Conducting Remedial Investigation/ Feasibility Studies
for CERCLA Municipal Landfill Sites" (EPA, 1991). By
signing the AOC, the Respondents agreed to do the work
described in these Plans which they helped prepare.
The Respondents agreed with this streamlined
presumptive remedy approach for the RI/FS at the time
they signed the AOC. Section IV of the AOC, entitled
"Statement of Purpose,"14 states:
13 In response to EPA's offer to participate in the RI/FS scoping
process, some of the Respondents opted to participate, and some declined.
14 Page 3, Paragraph 7. of the- AOC.
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. "The goal of EPA, Respondents, and the
Tulalip Tribe is for construction of the
presumptive remedy for this site to begin
during the Summer of 1995. Preparation of
the design documents and specifications for
the response action to implement the
presumptive remedy, which will be governed by
a separate agreement or an amendment to this
Consent Order, may begin prior to completion
of the feasibility study of the Source Area
Containment. In order to achieve this goal,
Respondents, EPA and the Tulalip Tribe
recognize that agreement may be required on
the conceptual design of one or more of the
containment component(s) of the presumptive
remedy before the final feasibility study of
the Source Area Containment is approved by
EPA under this Consent Order."
When they signed the AOC, the Respondents agreed upon a
data collection approach that they had extensive
participation in developing, and that was consistent
with EPA's guidance on presumptive "remedies. In fact,
the Work Plan for the RI/FS, which was incorporated
into the AOC signed by the Respondents, on page 4-1
states that:
"Containment technologies that are applicable
to the Tulalip Landfill include capping and
control of landfill gas, leachate, and
groundwater. A relatively extensive
geotechnical investigation has been designed
for the RI. Results are expected to
facilitate evaluation of detailed containment
alternatives and thereby accelerate remedial
design and implementation. Additional RI
tasks to determine the nature and extent of
contamination and the associated risks to
human health and the environment are
unnecessary for the Tulalip Landfill proper
since a presumptive remedy for source control
has been selected."
Thus, the Respondents had agreed to the streamlined
presumptive remedy approach when they signed the AOC
which specifically identified capping as an "applicable
containment technology for the Tulalip Landfill."
2.7.2 Additional Comment Under C.: The commentor asserts
that EPA improperly considered the Tulalip Tribes'
future land use plans when selecting Alternative 4c.
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Response: EPA disagrees with the commentor's
assertions that the Region improperly considered the
Tulalip Tribes' future land use plans when selecting
the interim remedial action in this ROD. See, also,
EPA's Response to Comment 11.27. In fact, obtaining
Tribal acceptance of the selected interim remedy is, in
the case of the Tulalip Landfill Site, one of the nine
NCP remedy selection criteria (state acceptance is a
modifying criteria) EPA must consider when evaluating
remedial alternatives. See Section 104 of CERCLA,
42 U.S.C. § 9604, and 40 C.F.R. §§ 300.430 (e) (9) (iii)
and 300.515. Moreover, the AOC which was negotiated
with the Respondents and the Tulalip Tribes
specifically provides for the Tribe to submit its plans
for future land use at the Landfill. The purpose of
the submittal was to inform EPA and the PRPs so that
the Tribes' plan could be considered in the development
of alternatives.
On October 19, 1995, the Tulalip Tribes submitted
comments'during the public comment period for the
Proposed Plan that express support for the preferred
alternative in the Proposed Plan, and "provided reasons
for their support. This comment letter is included in
the AR for this Site. In general, the Tribes' letter
expresses concerns about risks posed by the Site, and
describes their views on the effectiveness of the
various interim remedial alternatives presented in the
Proposed Plan.
Because Tribal acceptance is, in the case of Tulalip
Landfill, one of the nine criteria in the NCP against
which EPA must evaluate alternatives, EPA is required
to consider Tribal support (or lack thereof) when
selecting an interim remedy for the site. EPA has
considered Tribal support of Alternative 4c in
accordance with the requirements of CERCLA and the NCP.
However, the commentor seems unclear about the
respective roles of EPA and the Tribes with respect to
remedy selection. In accordance with CERCLA Section
104 and Executive Order 12580, selection of the interim
remedy is solely EPA's decision, not the Tribes'.
Historically, EPA has been criticized for selecting
remedies that have, in effect, "placed a fence around
the site" and prohibited any future productive use of
the site. Accordingly, relatively recent EPA guidance
indicates that EPA should consider future land use
during the remedy decision process. See "Land Use in
the CERCLA Remedy Selection Process", OSWER Dir. No.
9355.7-04 (May 25, 1995), (EPA, 1995c).
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EPA notes that it is unlikely that a landfill cover
would be selected solely on the basis of a landowner's
desire to .develop the land. While a landfill cover
would allow some limited use or development on the
landfill surface, a landfill surface is not an ideal
surface for future development and significant
restrictions are often necessary to prevent damage to
the cover system. Accordingly, the selected remedy
includes institutional controls to prevent damage to
the cover system. When design and construction of the
interim remedy are complete, EPA and the Tulalip Tribes
shall develop a document entitled "Routine Use of
Tulalip ('Big Flats') Landfill" (Tulalip Tribes, 1994),
to ensure the continued integrity of the cover system.
Any future commercial or development activity on the
landfill surface will require advance, written
agreement between EPA and the Tribes to ensure the
continued integrity of the cover system. See Section
10.1 of the ROD for further details.
2.8 Comment: "C.I. The Proposed Plan's Focus On Reducing
Leachate Discharges Is Inconsistent With Region 10's
Failure to Enforce the Clean Water Act at the Site
Since 1986." [3]
2.8.1 Additional Comments Under C.I.: The commentor believes
that the Region acted in an arbitrary and capricious
manner by failing to enforce the Tribe's NPDES permit
which prohibits discharges of pollutants into navigable
waters unless authorized by a permit issued pursuant to
Section 402 of the Clean Water Act (CWA), and instead
selecting a remedy 'in the*'Troposed Plan which has as a
primary objective reduction of leachate from the
landfill. [8] [18]
Response: The Region disagrees with the commentor's
assertions that the Region acted inconsistently under
the CWA and CERCLA with respect to enforcement of the
Tribes' NPDES permit versus proceeding with remedial
action under CERCLA.
EPA's obligation to take enforcement actions for
violations of NPDES permits is wholly discretionary.
EPA is not required by the statute to take enforcement
action against a person who is in violation of a permit
because effluent standards or limitations are being
exceeded according to the terms of the permit. EPA has
been given the discretion to decide whether to use the
enforcement powers under the CWA against violators of
NPDES permit conditions. The Agency was given this
discretion in order to be able to use all of its
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"tools", such as remedial action under CERCLA, in
deciding what is the best way to respond to releases of
hazardous substances from a site. In some cases,
enforcement of existing permit conditions may be the
best way to effectuate a timely and adequate response
to such a release of hazardous substances. In other
cases, pursuit of an enforcement case under the CWA may
result in needless delays due to litigation, which
would have the untenable result of allowing the
discharges of hazardous substances to continue pending
the outcome of such litigation.
In the case of the Tulalip Landfill, EPA Region 10
decided that the use of its CERCLA remedial action
tools, rather than its enforcement tools under the CWA,
to address the releases of hazardous substances was the
best use of limited Agency resources and was the most
timely and cost-effective method available to the
Agency at the time that decision was made. By using
CERCLA, EPA is addressing the source of the discharge
and preventing future generation of leachate.
In addition, Section 505 of the CWA permits any citizen
to commence a civil action against any person allegedly
in violation of an effluent standard or limitation or
an order issued by EPA regarding such a standard or
limitation. This citizen suit provision is meant to
provide a measure of policing of NPDES permit
compliance in the absence of the use of EPA's
discretionary enforcement authority for NPDES permit
noncompliance.
This commentor, in fact, utilized the citizen suit
provision of the CWA by bringing suit on behalf of his
clients, who are Respondents to the RI/FS AOC, against
the Tulalip Tribes of Washington and Federal
defendants. The claims were based on violations of the
Tribes' NPDES permit. The Court dismissed the
commentor's clients' claims based on the jurisdictional
bar of Section 113(h) of CERCLA.
The commentor, in his clients' citizen suit action,
asked the Court to enjoin further unpermitted
discharges of pollutants from the landfill and to
require compliance with the terms of the Tulalip
Tribes' NPDES permit. The commentor further asked the
Court to order EPA to enforce the CWA against the
Tulalip Tribes and BIA, including enforcing the terms
of the expired NPDES permit. As the United States
argued in its brief for the United States of Appeals in
Josie Razore and John Banchero v. The Tulalip Tribes of
Washington, No. 94-35985 (9th Cir), at page 26, "There
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is no way to stop discharges from the landfill, or to
bring the site into compliance with the terms of the
expired NPDES permit, without undertaking some sort of
response action."
EPA, relying on its technical expertise and enforcement
discretion, chose not to address the leachate problem
through enforcement of the CWA, but rather, chose to
address the environmental problems at 'the Site by
developing an appropriate response action under CERCLA.
CERCLA was specifically established to provide a
comprehensive statutory scheme to address and
accomplish the cleanup of actual or threatened releases
of hazardous substances. It was under CERCLA that EPA
believed the most comprehensive and technically viable
response could be developed to address the leachate
problem as well as the other environmental problems at
the Site. EPA maintains that this is the most rational
and responsible approach given the Agency's various
legal authorities, and is confident that the
alternative it has selected in the ROD to address
Source Area contaminants is the most viable after
taking into consideration all required factors.
The commentor -also refers to a Region 9 Superfund Site
in support of his contention that the Region 9 Site is
"remarkably similar" to the Tulalip Landfill. Since
the Region 9 Site ROD specified "no-action," the
commentor suggests that Region 10 is being inconsistent
in requiring "action" to be taken at the Tulalip
Landfill. Region 10 disagrees with the commentor's
description of the Region 9 Site being "remarkably
similar" to the Tulalip Landfill. The Region 9 Site is
the Ordot Landfill in Guam. That Site is an operating
municipal-landfill. Tulalip is not an operating
landfill-. The Ordot Site "no action ROD" stated that
CERCLA action was "inappropriate at this time"
(emphasis added) "based on several facts," which were
as follows:
"1) the Ordot Landfill is an operating
municipal landfill;
2) all but approximately 4 to 7 acres of the
47 acre site are active waste disposal areas;
3) the 4 to 7 inactive acres are down-gradient of
the active waste disposal areas or are immediately
adjacent to active waste disposal areas;
4) any remedy for the inactive areas will likely
be affected by activities at the active waste
disposal areas or continued surface flows through
the landfill;
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5} the bulk of any environmental impacts from the
landfill will result from activities at the active
waste disposal area;
6) the landfill, by applying standard operation
practices to control landfill leachate, can
effectively reduce or eliminate the surface flow
of leachate to receiving waters;
7) EPA has issued an order under the Clean Water
Act that requires the Guam Department of Public
Works to cease discharge of leachate from the
landfill to the nearby river; and
8) EPA data, although too limited for
comprehensive conclusions, has not demonstrated
any imminent and substantial endangerment to human
health or welfare or the environment."
"EPA concludes that threats to human health and
the environment currently identified at the
landfill are due to poor operation practices, and
can best be mitigated through addressing
operations and maintenance of the landfill itself
including improved leachate control measures
consisting of capping and surface water control.
EPA concludes that the appropriate mechanism for
implementing these controls is through enforcement
of the Clean Water Act. The responsibility for
implementing these controls lies with the landfill
operator, the territory of Guam. Expenditures
from the Superfund for these purposes are not
appropriate. Further, EPA concludes that any
remedial action to address the inactive portion of
the landfill potentially appropriate for response
under CERCLA would be jeopardized or nullified
unless operation practices at the active disposal
areas are improved to reduce leachate formation
and prevent discharge of leachate. The design for
improved operations at the active disposal areas
must consider the inactive portion due to the
nature of the site and thus would make a separate
CERCLA remedial action unnecessary." (Emphasis
added) (Winiecki, 1995a, Attachment M, at p.l &
2).
The differences between the Tulalip Landfill and the
Ordot Landfill are great. The Ordot Landfill is
primarily an operating municipal landfill with the
primary concern being leachate coming from the active
waste disposal areas through a surface water pathway.
EPA Region 9 found that "the surface flow through the
landfill is the source of the leachate, the site is
hydrologically isolated from the island's sole-source
aquifer, there is an absence of organic contaminants,
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inorganic contamination is below the appropriate MCLs,
and no air quality problems exist" (Winiecki, 1995a,
Attachment M, at p. 2). In contrast, at Tulalip, the
landfill ceased operations in 1979, and the leachate is
being generated as a result of infiltration of
precipitation and is discharging to both surface waters
and groundwater. In addition, a cap was identified as
one of the necessary components of the remedy under the
Clean Water Act at the Ordot Landfill.
Further, unlike the Ordot Landfill, the Tulalip
Landfill is hydrologically connected to both the
groundwater and the surface waters and is adjacent to
sensitive wetlands. There are numerous exceedances of
comparison numbers that are considered to be protective
of human health and the environment at the Site in all
media sampled during the RI. These comparison numbers
include standards, criteria and risk-based chemical
concentrations that are protective of human health and
the environment for this interim remedial action.
Thus, it is abundantly clear that the Ordot Landfill
and the Tulalip Landfill are not "remarkably similar",
and that the commentor's comparisons of the Tulalip
Landfill to the Ordot Landfill are without merit.
It is also clear that one of the primary reasons Region
9 chose a no action alternative was the fact that the
operating areas of the Ordot landfill would adversely
affect any remedial action EPA would have mandated for
the small inactive areas of the Ordot Landfill. In
fact, the no action ROD for the Ordot Landfill states
that EPA will continue to monitor the effectiveness of
measures taken by Guam15 to install the proper
leachate collection systems and capping, and that "[i]n
choosing the no action alternative EPA reserves its
authority to perform additional response actions should
the new information warrant such a decision." Thus,
EPA Region 9 recognized the fact that it may yet have
to take action at the Ordot Landfill in order to
protect human health and the environment.
2.8.2 Additional Comment Under C.I.: The commentor, in his
footnote #28, states that there are other Region 10
documents which "belie the Proposed Plan's expressed
concern with leachate discharges from the Site." The
commentor goes on to suggest that these previously-
drafted Region 10 site documents indicate that the
risks posed by the Site are not as serious as the
Region has indicated in the Proposed Plan.
15 The territory of Guam concurred on this no-action ROD.
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Response: The interim action ROD determines that
discharges from the landfill, if not addressed, may
present an imminent and substantial endangerment to
human health and the environment. This determination
is based on relatively recent RI/FS documents,
including the final Remedial Investigation (RI) report,
the Revised Feasibility Study for Source Area
Containment (FS), and the Risk Assessment for Interim
Remedial Action (Streamlined Risk Assessment). The
Streamlined Risk Assessment documents numerous
exceedances of comparison numbers that are considered
to be protective of human health and the environment at
the Site in all media sampled during the RI. These
comparison numbers include standards, criteria and
risk-based chemical concentrations that are protective
of human health and the environment for this interim
remedial action. The geological and hydrogeological
information contained in the RI, in combination with
the Risk Assessment which shows landfill contaminants
which are common across various media, indicate that
the landfill is a source of chronic contamination to
the surrounding sensitive environment. Based on this
information, EPA appropriately concludes that
contaminant discharges from the landfill may present an
imminent and substantial endangerment to human health
and the .environment.
The commentor appears to be referring specifically to a
"removal assessment" written by Bill Glasser, dated
April 22, 1992 (Glasser, 1992). A copy of this
document is included in the AR for this Site. Contrary
to the commentor's interpretation, this document does
not state that no further action is necessary at the
Site. Rather, the document states that signs are
necessary to warn people from using the landfill and
surrounding areas, and notes that Mr. Glasser observed
"no imminent or acute threats to human health or
environment" at that time, based on his inspection of
the Site and the information available to him at that
time.
Removal assessments are typically conducted at all NPL
sites early in the CERCLA process, and thereafter on a
periodic basis. The purpose of a removal assessment is
to assess whether any emergency actions need to be
taken at a site prior to the start of the RI/FS. Mr.
Glasser's use of the word "acute" is indicative of the
nature of the removal assessment document as evaluating
the need for any emergency response actions.
The removal assessment states that "no further action
by the removal program is recommended." [emphasis
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added]. At the time this document was written, Mr.
Glasser was acting in his capacity as an On-Scene
Coordinator (OSC) for the EPA Region 10 removal
program. The purpose of the removal program is to
conduct emergency removal actions. Emergency removal
actions are often conducted at Superfund sites early in
the CERCLA process to address any acute threats that
constitute an emergency situation, to stabilize the
site so that the longer-term remedial
investigation/feasibility study and remedial
design/remedial action processes can continue at the
Site without endangering the lives of Site workers, or
people using the areas near the Site. The conclusion
of an OSC under the removal program and in particular,
Mr. Glasser's decision as an OSC at the Tulalip Site,
that no emergency actions are necessary at a given
point in time to stabilize at Site in no way implies
that the Site poses no risk which may require remedial
action under CERCLA.
At the time Mr. Glasser prepared this document, he did
not have access to the results of the RI, the source
area containment FS, or the streamlined Risk
Assessment. Presently, based on the results of the
RI/FS and Streamlined Risk Assessment, EPA concludes
.— that the Site may pose an imminent and substantial
endangerment to human health and the environment. This
finding suggests that action should be taken to contain
discharges at the Site in a prompt and effective
manner; however, discharges at these levels do not
constitute an emergency situation that requires an
immediate response.
EPA notes that Mr. Josie Razore and Mr. John Banchero,
represented by the commentor, filed a motion in the
Ninth Circuit for an emergency injunction ordering the
Tulalip Tribes to immediately control leachate
discharges at the Site because these leachate
discharges were causing "irreparable harm"' to the
environment. The commentor's arguments to the Ninth
Circuit on behalf of the AOC Respondents with regard to
irreparable harm caused by leachate discharges from the
landfill support EPA's decision to take an interim
remedial action at the Site.
2.9 Comment: "C.2. Region 10 Has Arbitrarily Denied the
Respondents' Requests to Test the Surface of the
Landfill." [3]
Response: EPA has never denied the Respondents'
request to test the surface of the landfill. EPA has
declined to enter into discussions with the Respondents
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to amend the RI/FS Work Plan to provide for the
collection of this data under the RI/FS AOC.
The Respondents initiated a formal dispute under the
RI/FS AOC with respect to their request for additional
surface sampling. This dispute is documented in the AR
for this interim remedial action. On August 4, 1995,
the EPA Region 10 Branch Chief, in accordance with the
RI/FS AOC dispute resolution procedures, issued the
following Determination regarding the Respondents'
request to conduct additional work, including
additional surface sampling (Gearheard, 1995a):
"Tulalip Landfill Administrative Order
on Consent (AOC) Dispute Resolution
Branch Chief's Determination on the
Request for RI/FS Work Plan Modifications"
"Issues Under Dispute:
The parties to the AOC have been unable to
resolve a dispute which has arisen over the
Respondents request to modify the Remedial
Investigation/Feasibility Study (RI/FS) Work
Plan at the Tulalip Landfill Superfund Site.
The modifications requested include the
collection of additional data to further
characterize contaminant concentrations in
surface water near the Site, and to further
characterize contaminant concentrations in
soil and standing water at the landfill. The
respondents would use this information to
support the Revised Source Area Containment-4
Feasibility Study (SAC-4 FS) alternatives."
"EPA notified the Respondents that the Agency
is not willing to amend the RI/FS Work Plan.
- The Respondents have objected to the Agency's
reasons for not amending the work plan. The
Agency's reasons include:
1. The Respondents have had ample opportunity to
identify the need for any additional work to
support the SAC-4 FS prior to submitting the
SAC-4 FS report;
2. The request for additional work contradicts
the Respondents own draft RI Report, which
concludes that no further work is needed to
complete the SAC-4 FS;
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3. The proposal for additional work is
structurally flawed and contains technical
deficiencies; and
4. Collection of the additional data would
result in delay of cleanup at the site."
"Background
The Respondents signed an Administrative
Order on Consent (AOC, EPA Docket No. 1093-
08-01-104/106) to conduct a Remedial
Investigation/Feasibility Study (RI/FS) at
the site. Pursuant to this AOC, the
Respondents agreed to conduct work in
accordance with a Work Plan for the RI/FS
which was structured in accordance with the
presumptive remedy of containment for the
source area. Data collection for the RI
began in November 1993. The draft RI was
submitted on February 4, 1995. The FS (SAC-4
report) was submitted on February 13, 1995.
The Respondents then submitted a request to
amend the RI/FS work plan on February 23,
1995. The requested amendment included the
collection of additional soil and water data
supporting the Respondents opinion that the
surface of the landfill, contrary to EPA's
position, does not present a risk to human
health or the environment, and that
groundwater discharges to the slough could
achieve Ambient Water Quality Criteria
(AWQC). EPA denied the request to modify the
work plan on April 12, 1995."
"In accordance with paragraph 61 of the AOC,
the parties have tried to resolve this
dispute informally without success. The
respondents served on EPA a notice of dispute
(letter of Wm. Roger Truitt dated April 26,
1995). EPA and the Respondents met on May
11, 1995, but no agreement was reached. On
August 4, 1995, the Respondents submitted a
request for the Branch Chief's determination
on the dispute. The Branch Chief's
determination follows:
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Determination
1. The Respondents have had ample
opportunity to identify the need for any
additional work to support the SAC-4 FS prior
to submitting the SAC-4 FS;
The Respondents contend that the AOC allows
the Respondents to identify the need for
additional work at any time during the RI/FS
process. The Respondents further contend
that it was EPA comments in a February 3
letter on the SAC-4 report which identified
the need for additional work. The
Respondents objected to EPA's determination
that the appropriate time to submit this
request was before issuance of the (SAC-4)
FS, since they had just received EPA's
comments.
EPA's position is that the Respondents were
erroneous in their conclusion that comments
provided by EPA (as noted in your letter
dated 'February 23, 1995) identified the need
for additional data. To the contrary, EPA
has determined that sufficient information
has been collected to date in order for EPA
to make a decision on an appropriate,
protective remedy, and that further data
collection is unnecessary.
Regardless of the erroneous conclusion made
by the Respondents which is the basis for
their request, the AOC states that EPA, in
its discretion, will determine whether the
additional data will be collected. Pursuant
to this discretion, EPA has determined that
the additional data will not be collected at
this time. The appropriate time to identify
the need for data collection would have been
earlier in the process, (e.g., during the
Remedial Investigation) so that the data
could have been incorporated into the SAC-4
report without delay. The Respondents did
not do so. As it is, sufficient data has
already been collected by the Respondents and
EPA has decided that the requested additional
data shall not be collected at this time.
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2. The request for additional work
contradicts the Respondents' own draft RI
Report, which concludes that no further work
is needed to complete the SAC-4 FS;
The Respondents state that in EPA's "August
12, 1995 letter" (emphasis added) the Agency
made the statement that the request for
additional work contradicts the Respondents
own draft RI report. For the record, this
statement was made in EPA's April 12, 1995,
letter. The Respondents contend that since
the letter which they claim precipitated the
need for additional data was not received
until February 3, and the draft RI report was
submitted February 4, it was impossible to
include the identification of the need for
additional work in the draft RI.
As stated above, in EPA's view, the
Respondents misinterpreted EPA' s_ comments
presented in our February 3, 1995 letter.
EPA's comments did not imply that additional
data needed to be collected. To the
contrary, EPA believes that the data
presented in the draft RI, and additional
modelling by the Respondents included in the
revised SAC-4 report, confirm EPA's position
that sufficient data already exist regarding
the risk from the landfill surface, and
groundwater migration, in order to make
decisions on selecting an appropriate,
protective remedy.
The Respondents dispute EPA's position that
sufficient data has been collected, since the
data collected to date, and the groundwater
modelling conducted by the Respondents,
indicate that several potential remedial
alternatives are not protective and do not
meet ARARs. These alternatives have thus
been eliminated from the analysis of
alternatives. The Respondents contend that
by not agreeing to amend the RI/FS Work Plan
to allow the Respondents to collect this
additional data, EPA is limiting the range of
containment alternatives under consideration.
The Respondents contend that collecting the
additional data would be necessary to
determine which of the non-capping
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alternatives, including those eliminated in the
screening process, are consistent with the NCP.
EPA continues to maintain that the
Respondents' statement in the draft RI that
no further work is necessary is accurate, and
contradicts the Respondents' claim that
additional work is needed. EPA believes that
current data allow the Agency to consider a
sufficiently broad range of alternatives, as
presented in the SAC-4 report, and as
described in the Proposed Plan for Interim
Remedial Action. EPA has determined that
additional data collection support of the
SAC-4 FS is not needed.
3. The proposal for additional work is
structurally flawed and contains technical
deficiencies;
The Respondents claim that EPA's April 12,
1995, comments do not provide enough
specifics on why their additional work
request is deficient, and do not provide
specifics on what would be-necessary to
correct the flaws and deficiencies.
EPA believes the level of detail provided in
its April 12 comment letter adequately
pointed out the deficiencies in the
Respondents proposal for additional data
collection. EPA did not provide further
comments on what would be needed to correct
the proposal because the Agency does not
believe that collecting the additional data
is needed in order to support the SAC-4
report nor to make a decision on the remedy.
Therefore, EPA has determined that the
Respondents' contention that EPA did not
provide enough specific comments on the
deficiencies of their proposal has no bearing
on EPA's decision that the work is not
needed.
4. Collection of the additional data would
result in delay of cleanup at the site;
The PRPs contend that EPA over-estimated the
amount of time it would take to complete the
additional data collection, and that the work
could be completed in time described by the
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Respondents in their February 23, 1995 letter
(final SAC-4 report by August 31, 1995).
EPA maintains its position that the
Respondents significantly under-estimated the
amount of time necessary conduct the
additional work. EPA maintains that it would
take much longer to carry out the necessary
steps: review, comment, negotiate work plan,
EPA approval of work, conduct field
activities, data analysis and review, report
preparation, EPA review and approval of final
SAC-4 report. EPA has determined that
collection of the additional data would delay
the agreed upon schedule for completion of
SAC-4 report, and this delay is unnecessary
since sufficient data has been collected to
date."
The Respondents subsequently appealed the Branch
Chief's Determination to the EPA Region 1C) Regional
Administrator. On October 18, 1995, the Depufy
Regional Administrator, acting for the Regional
Administrator, issued the following" decision regarding
additional surface sampling (Findley, 1995a):
"EPA's Final Determination: The Respondents
request to perform additional work is denied.
The rationale for this decision follows.
The Respondents asserted in their dispute
that the AOC allows the Respondents to
identify the need for additional work at any
time during the RI/FS process. The
Respondents" also asserted that it was EPA
comments in a February 3, 1995 letter which
raised the need for the collection of
additional data to support the FS. Since the
SAC-4 FS report was submitted by the
Respondents only 10 days after receiving
EPA's comments, the Respondents asserted that
they had an inadequate time to respond to
EPA's comments before submitting the SAC-4 FS
report. Therefore, the Respondents asserted
that their request was not untimely. The
Respondents also asserted that the request
was not inconsistent with the RI and believed
that EPA did not adequately explain the
deficiencies in their additional work
proposal.
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The Branch Chief, in his August 4, 1995
determination, wrote that the Respondents
were' erroneous in concluding that EPA's
February 3, 1995 comments identified the need
for collecting additional data. The Branch
Chief cited the AOC, which states that EPA,
in its discretion, will determine whether
additional data will be collected. The
Branch Chief upheld the Remedial Project
Manager's (RPM's) position (as detailed in
his April 12, 1995 letter) that sufficient
data had been collected to date upon which to
make a decision on a appropriate, protective
cleanup remedy using.the presumptive remedy
approach outlined in the AOC. The Branch
Chief also upheld the RPM's position that the
Respondents request was untimely, was
inconsistent with the draft RI, and contained
structural flaws and deficiencies.
My review of the record concludes that EPA
reasonably evaluated the Respondents' request
for additional work, and concluded that the
work was not necessary to support the
objectives of the RI/FS. In their review,
the RPM and the Branch Chief also determined
that the request for additional work was
untimely and would cause delays in the
cleanup. Although the RPM had determined
that the additional work was unnecessary, his
preliminary review identified several
deficiencies in the proposed work. I find
that the decisions by EPA staff and the
Branch Chief are consistent with EPA
authorities under CERCLA and the National
Contingency Plan. Further, Paragraph 36 of
the AOC, an agreement signed by the
Respondents, specifically provides that EPA's
decision on additional work is at its
discretion. I find that the record shows
that the RPM and the Branch Chief reasonably
determined that no additional work was
necessary, and that EPA decided, at its
discretion, to not authorize the work
suggested by the Respondents. For these
reasons, I uphold the decision of the Branch
Chief to deny the Respondents' request for
additional work.
This determination is EPA's final decision on
this dispute."
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EPA's decision not to amend the RI/FS Work Plan to
allow for additional sampling of the landfill surface
was therefore reasonable and justified, as EPA
carefully considered all of the Respondents' points and
concerns before EPA issued its final decision regarding
these disputes. Additional correspondence regarding
this dispute is included in the AR for this interim
remedial action. See also Response to Comment 2.9.1.
2.9.1 Additional Comment Under C.2.: The commentor also
states that, had EPA approved the AOC Respondents'
requests to amend the RI/FS workplan to allow the
testing of the surface of the landfill in a timely
manner, these results would have been available at the
time of issuance of the streamlined Risk Assessment and
the Proposed Plan for this interim remedial action.
Response: The AR shows that EPA responded in a timely
fashion to the Respondents' requests for additional
work. Both the EPA Branch Chief's Determination
(Gearheard, 1995a), and the EPA Regional
Administrator's decision (Findley, 1995a), note that
the Respondents' request was untimely. In addition,
given the Respondents' lack of consistent timeliness in
submitting RI data, EPA did not have reason to believe
that the Respondents would produce this additional
surface data prior to issuance of the Streamlined Risk
Assessment and Proposed Plan. All final RI data of
acceptable quality was due on May 4, 1995, with the
final RI Report. Some of this data was provided to EPA
as late as October, 1995, well after the streamlined
Risk Assessment was finalized and the Proposed Plan
issued. EPA was also concerned that competition for
analytical resources needed for the additional surface
sampling may have contributed to longer delays in
submitting the late RI/FS Work Plan data that was
submitted in October 1995. Therefore, EPA believes
that it has acted reasonably in denying the AOC
Respondents' requests to conduct more extensive surface
soil sampling at the Tulalip Landfill, after fully
considering the need for additional data and the
potential for delay in addressing the ongoing
discharges of hazardous substances into the
environment.
2.9.2 Additional Comment Under C.2.: The commentor suggests
that the 1988 surface data used by EPA as part of the
streamlined Risk Assessment was "limited and
unreliable" data. [8] [17]
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Response: EPA included 1988 surface data in the
streamlined Risk Assessment, not for the purpose of
fully characterizing the entire landfill surface, but
to point out that existing site data from 1988
indicates that some locations of the landfill surface
were contaminated at the time those samples were taken.
At the sample locations, hazardous substances were
found at levels that exceeded comparison numbers that
are considered to be protective of human health and the
environment at the Site in all media sampled during the
RI. These comparison numbers include standards,
criteria and risk-based chemical concentrations that
are protective of human health and the environment for
this interim remedial action. EPA agrees that 5
samples are an insufficient number of samples to fully
characterize the 147 acre landfill surface, and that
the 1988 data is significantly older than RI/FS data.
However, sampling of the landfill surface is not
necessary to proceed with a presumptive remedy at
municipal landfill sites. As the EPA guidance document
"Presumptive Remedy for CERCLA Municipal Landfill
Sites" (EPA, 1993a) states on page 5:
"A quantitative risk assessment... is not
necessary to evaluate whether the containment
remedy addresses all pathways and
contaminants of concern associated with the
source."
* * * *
"Streamlining the risk assessment of the
source area eliminates the need for sampling
and analysis to support the calculation of
current or potential future risk associated
with direct contact."
These EPA policy statements clearly indicate that EPA
believes it is not necessary to sample the landfill
surface before making a decision to proceed with an
interim action to contain the landfill wastes.
However, because the 1988 data was available and
considered reliable by EPA, it was included it in the
Streamlined Risk Assessment.
Recent surface water data collected by the Respondents
during the RI/FS at leachate seep SP-01 supports the
1988 data because it indicates that, at this location,
surface water contamination on the landfill surface
still exists. Sampling data from seep SP-01, the only
leachate seep sampled during the RI/FS which originates
on the landfill surface, exceeded comparison numbers
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that are protective of human health and the environment
(see interim ROD, Table 11-1) . See also Response to
Comments 10.1 - 10.4 for responses to comments about
the quality of the 1988 data.
2.9.3 Additional Comment Under C.2.: The commentor asks why
EPA considers the 1988 data to be adequate, while EPA
considered the Respondents' proposal for additional
surface sampling to be inadequate.
Response: The Respondents' request to conduct
additional surface samples was the subject of a formal
dispute (see Response to Comment 2.9 for a complete
explanation of why EPA declined to amend the AOC to
conduct this additional sampling). EPA does not
maintain that the five surface soil and surface water
samples taken in 1988 are sufficient to "adequately"
characterize the entire landfill surface. However, in
EPA's view, because the 1988 data is available and EPA
considers it to be reliable, it is appropriate to
include this available data in the Streamlined Risk
Assessment. EPA believes the 1988 data does adequately
characterize landfill surface conditions at those 5
sample locations at the time they were taken, even
though 5 sample locations cannot be considered
representative of the entire landfill surface.
It should be noted that EPA guidance on presumptive
remedies, which is consistent with the NCP, does not
require EPA to fully characterize" any medium before
making a decision on whether remedial action is
warranted to address contamination in that medium.
See also Response to Comments 10.1 - 10.4 for responses
to comments about the quality of the 1988 data.
2.9.4 Additional Comment under C.2.: The commentor states
that EPA used unreliable data (the 1988 data) to rule
out non-capping alternatives in the Proposed Plan, and
that even the 1988 data fail to show a risk to human
health and the environment.
Response: The 1988 surface data was given appropriate
consideration by EPA during the remedy selection
process, acknowledging the limited number of samples
and the age of the data. The 1988 surface data was not
a critical factor in eliminating any alternatives from
consideration, nor in EPA's selection of Alternative 4c
as the most appropriate alternative for interim
remedial action. If the 1988 surface data had been set
aside and not considered at all by EPA, the comparative
analysis of alternatives in the interim ROD would still
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have led EPA to conclude that Alternative 4c provides
the best balance of trade-offs with respect to the nine
criteria an addressing the remaining pathways of
concern.16
Alternative 4c was selected in the interim ROD because
it provided the best balance between the nine NCP
criteria and met the remedial action objectives. Some
of the other alternatives would have met the remedial
action objective of prevention of direct contact;
however, those alternatives were ruled out in the
interim ROD based on an analysis of the nine NCP
criteria and their ability to meet the other remedial
action objectives.
EPA disagrees with the commentor's assertion that the
1988 data show no threat to human health and the
environment. "Table 6-4 - Summary of On-Source Data
that Exceed Ecological Comparison Numbers" from the ROD
indicates that, in 1988, at 5 sample locations on the
landfill surface, concentrations of the following
chemicals in surface water exceeded comparison numbers
that are considered protective of ecological resources:
Chemical Frequency of Exceedances
Phenanthrene 1/5
Bis(2-ethylhexyl)phthalate 1/5
Cadmium - total 1/5
Chromium - total - 2/5
Copper - total 4/5
Iron - total 5/5
Lead - total 2/5
Nickel - total 3/5
Zinc - total 4/5
In addition to these 1988 surface water exceedances of
comparison numbers, EPA notes that the 1988 surface
soil data exceeded the comparison number for bis(2-
ethylhexyl)phthalate at one sampling location. Based
on these exceedances of comparison numbers, EPA
believes it is reasonable to conclude that in 1988, at
these five sampling locations on the landfill surface,
surface -water presented a potential risk to the
environment. Though the 1988 data may not be
representative of current conditions at these sample
16 These pathways include leachate passing through the perimeter landfill
berm and discharging to wetlands, leachate on the landfill surface (SP-01),
Zone 2 groundwater, off-source surface soils, off-source subsurface soils,
off-source surface sediments, and off-source subsurface sediments.
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locations, and does not fully characterize the 147-acre
area, consideration of this data is still useful and
appropriate because it represents conditions at five
locations on the landfill surface in the relatively
recent past. See also Responses to Comments 10.1 -
10.4.
2.10 Comment: "C.3. Region 10 Has Arbitrarily Refused to
Allow the Respondents to Conduct Tests Related to the
Discharge of Zone 2 Groundwater to Surface Water." [3]
Response: See Response to Comment 2.10.3.
2.10.1 Additional Comment Under C.3.: The commentor states
that EPA is incorrect in expecting that Alternative 4c
in the Proposed Plan will eliminate the migration of
leachate into Zone 2 groundwater in the short term.
Response: EPA disagrees with the commentor regarding
the effectiveness of Alternative 4c in eliminating
migration of leachate into Zone 2 groundwater. As was
stated by the Respondents in the Revised SAC-4 RI/FS
that they prepared, on pages 87-89 (discussing
Alternatives 4b and 4c), the low permeability cover (or
"cap") for Alternative 4b:
"...essentially eliminates infiltration
and leachate generation, thereby
eliminating seep and groundwater
migration and achieving all the seep and
groundwater RAOs [remedial action
objectives]...."
The permeability of the cover discussed in Alternative
4b is the same as would be required for Alternative 4c.
Thus, the AOC Respondents' own consultant agrees with
EPA regarding the effectiveness of the cap required by
the selected alternative, Alternative 4c,
In addition, the Proposed Plan on page 10 states that
Alternative 4c "...is expected to eliminate the
perimeter berm leachate seeps within two years, and
basically eliminate the generation and migration of
leachate in the deeper groundwater to the sloughs."
It may be true that Alternative 4c will allow more
leachate to be released into the environment in the
short term than Alternative 2b, which is the
alternative supported by the Respondents. However, in
the long term, Alternative 4c would release
significantly less leachate than Alternative 2b,
thereby reducing the amount of mass contaminant loading
to the environment (mass contaminant loading was
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identified in the Streamlined Risk Assessment as one of
the primary risk concerns at the Tulalip Site). The
NCP gives preference to long-term effectiveness over
short-term effectiveness. See 55 Fed. Reg. 8725; 40
C.F.R. section 300.430(f)(1)(ii)(E). Construction of
Alternative 4c will allow the existing leachate mound
within the landfill waste to dissipate gradually, by
the force of gravity, through the perimeter leachate
seeps and downward into Zone 2. Once the leachate
mound recedes, the cover, by preventing new
infiltration of precipitation, effectively prevents the
generation and migration of new leachate. In contrast,
Alternative 2b (if it were to work as well as the
Respondents have predicted) would allow a greater
initial leachate reduction by reducing the volume of
the existing leachate mound more quickly, but would
continue to allow significant amounts of leachate to
migrate into the environment in perpetuity.
"Comparison of the Leachate Collection and Treatment
Alternative (2b) with the FML Cover Alternative (4c),
Colder Associates, October 24, 1995" (Colder, 1995b)
compares the cumulative leachate flow out of the
landfill into the environment of Alternatives 2b and
2b(ii) with that expected for Alternative 4c. Figure
4-2 from the above Colder report (Colder, 1995b)17
shows that, for approximately fifteen years,
Alternatives 2b and 2b(ii) are expected to allow
slightly less leachate to escape into the environment.
However, with Alternative 4c, after this 15 year
period, leachate production subsides. In contrast,
under Alternatives 2b and 2b(ii), the leachate
continues to escape from the landfill at a rate of
approximately 80 million gallons every 10 years in
perpetuity. If the collection system proposed for
Alternatives 2b and 2b(ii), an unproven technology,
turns out to be less effective than the Respondents
have predicted (a distinct possibility, given that
alternatives 2b and 2b(ii) are unproven technologies),
the predicted leachate escapement rate for these
alternatives of 80 million gallons every ten years
could be substantially higher.
2.10.2 Additional Comment Under C.3.: The commentor suggests
that the RI/FS sampling showed that there were no
exceedances of surface water quality criteria at any
location.
17 A copy of this figure is provided for the convenience of the reader at
the end of Appendix D in Attachment C.
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Response: EPA disagrees with this comment. Excluding
leachate data collected from the perimeter leachate
seeps, there were three surface water samples taken
outside the landfill perimeter during the RI/FS that
exceeded surface water comparison numbers: one
exceedance of arsenic and one of dibenz(a,h)anthracene
at sample location R1-SW-SC24-S2 that exceeded human
health comparison numbers, and one exceedance of lead
that exceeded the ecological comparison number at
sample location R1-SW-SG37.
In addition to these three exceedances of water samples
that were specifically referred to as "surface water"
samples in the RI/FS Work Plan, samples taken from the
perimeter leachate seeps are also a type of surface
water sample, even though they are explicitly referred
to in the RI/FS Work Plan as "leachate seep" samples.
Under Washington state law, which requires the
application of ambient water quality criteria to be
measured at the point where groundwater enters surface
waters,18 the comparison number exceedances measured
in the perimeter berm leachate are exceedances of
surface water criteria. EPA notes that numerous
chemicals were found in the leachate seep waters, and
that the levels of many chemicals exceeded the
comparison numbers that are considered to be protective
of human health and the environmental resources. See
Tables 6-2, 6-4, and 6-5 in the interim ROD for more
specific information .regarding leachate seep
exceedances. Thus, it is EPA's position that the
numerous samples of leachate seeps outside the
perimeter of the berm demonstrate that surface waters
are contaminated by discharges from the Site.
The RI/FS approach for evaluating Zone 2 groundwater
was to measure groundwater chemical concentrations at
13 perimeter landfill berm wells. Using this data from
the berm wells, the Respondents used a groundwater
modeling technique to estimate the contaminant
concentrations that would be expected at the location
where Zone 2 groundwater enters the sloughs, which is
where State Water Quality Criteria must be measured
according to Washington state law that EPA has
identified as being relevant and appropriate for this
18 No mixing zones in surface water (i.e., the sloughs) are permitted
under State law for measuring compliance with these discharges. This issue of
mixing zones in surface water was the subject of a formal dispute resolution
process under the RI/FS Administrative Order on Consent. See Response to
Comment Section 2.9 for more information on this dispute. See ROD Section
11.2 - Compliance with ARARs.
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Site. The results of this groundwater modeling
indicated that, in general, one would expect to see
contaminants in the berm wells diluted by a factor of 5
to 9 from the time they leave the perimeter berm wells
to the time they reach the sloughs. Taking these
dilution factors into account, exceedances of
comparison numbers at the Zone 2/slough interface would
be expected. See Section 6.0 of the interim ROD.
Ammonia nitrogen exceeds comparison numbers for all
samples taken at the high end of the predicted
concentration reduction range (73 of 73). Based on the
exceedances of comparison numbers in Zone 2 groundwater
in the berm wells and predicted through groundwater
modeling at the sloughs, it is appropriate to conclude
that discharges from the landfill are resulting in
exceedances of human health and ecological comparison
numbers at the Zone 2/slough interface, which
represents a potential threat to human health and the
environment.
2.10.3 Additional Comment Under C.3.: The commentor states
that EPA denied the Respondents' proposal to amend the
RI/FS workplan to perform Zone 2/surface water
interface testing for the "same reasons" that EPA
denied their request to test the surface of the
landfill.
Response: The Respondents' request to install - •
additional groundwater sampling wells in the wetlands
surrounding the landfill was the subject of a formal
dispute under the RI/FS AOC. In accordance with the
AOC, the EPA Region 10 Branch Chief issued a
Determination regarding the Respondents' request. The
Respondents appealed this decision to the EPA Region 10
Deputy Regional Administrator, who subsequently issued
a decision on this matter. The Branch Chief's
Determination and the Deputy Regional Administrator's
Decision are provided above in EPA's Response to
Comment 2.9.
2.10.4 Additional Comment Under C.3.: The commentor states
that the AOC Respondents disagreed with EPA regarding
whether an aquatic biota inventory was needed under the
RI/FS to show effects of Zone 2 groundwater discharges,
which Respondents believe is necessary in order to
define risks posed by the site.
Response: As EPA concluded during the formal dispute
process, an adequate biota inventory already exists for
the Site (Weston, 1992) ; therefore, a second inventory
is not necessary. In addition, there are biological
inventories available for the Snohomish River Delta in
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general (NOAA, 1991). See also Response to Comment
11.45. EPA's presumptive remedy guidance does not
require EPA to show that there are specific organisms
at the Site that could be harmed by specific
chemicals.19 The purpose of the presumptive remedy
approach is to streamline the RI/FS and Risk Assessment
process so that expenditures of time and money are
reduced while ensuring that an appropriate remedy is
selected. The presumptive remedy approach allows EPA
to compare site sample data (contaminant concentration
levels) against standards and criteria (some of which
were later identified as chemical-specific ARARs in the
interim ROD), and against risk-based chemical
concentrations if standards or criteria are
unavailable. Where established standards for one or
more contaminants in a given medium are clearly
exceeded, remedial action is generally warranted20,
and selection of a containment remedy to address the
potential pathway(s) posed by that medium is
appropriate. EPA concludes that based on numerous
exceedances of state surface water comparison numbers
in groundwater at the site, and based on the results of
the Respondents' modeling that shows that some of these
contaminants are unlikely to meet state water quality
standards at the Zone 2/slough interface (see Responses
to Other Comments in Section 2.10), remedial action is
warranted to address the Zone 2 groundwater pathway.
2.11 Comment: "C.4. Region 10 Arbitrarily Dictated the
Content of the Respondents' SAC Reports" [3]
2.11.1 Additional Comment Under C.4.: The commentor also
states that despite EPA's approval of the Respondents'
contractors, EPA has rejected numerous recommendations
and conclusions made by the Respondents' contractors.
The commentor also states that EPA initially denied the
collection of dissolved metals data, and then EPA
severely limited its use in evaluations by the
Respondents' contractors, despite EPA's use of
dissolved metals data at other sites. The commentor
then states that EPA did not offer a rational basis for
not allowing the Respondents to perform additional
testing.
19 However, Appendix B of the Risk Assessment for Interim Remedial Action
contains information about specific species that are present at the Site which
could be harmed by chemicals that are discharging from the landfill.
20 See "Presumptive Remedy for CERCLA Municipal Landfill Sites" (EPA,
1993a, page 4.)
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Response: EPA disagrees that the Agency has
arbitrarily dictated the content of the Respondents'
SAC reports. To the contrary, EPA has provided the
Respondents with a clear record showing how EPA's
comments and decisions on all of the SAC Reports have
been made consistent with CERCLA, the National
Contingency Plan (NCP), and the Agency's authority
under the Administrative Order on Consent (AOC), under
which the SAC reports were developed by the
Respondents. Pursuant to this AOC, the Respondents
agreed to develop cleanup alternatives using the
presumptive remedy of containment. The AOC states that
EPA makes the final decision on the contents of all
reports. EPA retained a respected consulting firm (Roy
F. Weston, Inc.) to provide expertise and assistance in
reviewing the SAC reports submitted by the Respondents.
EPA also used qualified and competent in-house
technical advisors in preparing comments on SAC
reports.
Using this expertise, EPA evaluated cleanup
alternatives proposed by the Respondents against the
nine criteria outlined in the NCP. Those alternatives
which met the two threshold criteria protection of
public health and the environment, and compliance with
applicable or relevant and appropriate requirements
(ARARs) were retained for further consideration. The
alternatives which were retained were then evaluated
against the remaining seven NCP criteria. EPA chose
Alternative 4c as the alternative which provided the
best balance of all nine NCP criteria. See interim ROD
Section 9.0 - Summary of Comparative Analysis of
Alternatives. EPA also determined that Alternative 4c
is cost effective (see interim ROD Section 9.0).
The Respondents have cited EPA's rejection of some non-
capping alternatives as an indication that EPA
arbitrarily dictated the contents of Feasibility Study
reports. EPA disagrees that it has arbitrarily
dictated the contents of the SAC Reports. EPA's basis
for rejecting the non-capping alternatives is discussed
in detail as part of a dispute with the Respondents and
is included in the AR for this site. To summarize, EPA
excluded two non-capping alternatives, Alternatives 3a
and 3b, from further consideration in the Feasibility
Study because, contrary to the Respondents' claim,
these alternatives do not meet the two threshold NCP
criteria (protectiveness and compliance with ARARs),
and because they are inconsistent with the presumptive
remedy of containment. See interim ROD Section 8.12 -
Other Alternatives.
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The Respondents also state that Region 10 has rejected
evaluations and conclusions presented by the
Respondents' experts in the course of preparing the
cleanup alternatives. The Respondents provide two"
examples, EPA's limitations on the use of dissolved
metals data, and EPA's denial of the Respondents'
request for additional field work to collect additional
data. Both of these issues were also part of disputes
with the Respondents under the terms of the AOC. (The
dispute regarding the collection of dissolved metals
samples was resolved informally.) These disputes were
resolved by letters from the Deputy Regional
Administrator of EPA, and are part of the AR for the
site (Gearheard, 1995b, Findley, 1995b). See also
Response to Comment 2.9. As for additional field work
requested by the Respondents, EPA decided that the
additional work was not needed in order to select a
reasonable, cost-effective cleanup remedy, containment
of the source area. The record shows that EPA provided
a rational basis for these decisions. Correspondence
with the Respondents dated April 12, 1995, (Winiecki,
1995e), also provides the rationale for EPA's decision.
2.12 Comment: "C.5. Region 10's Reliance on the State of
Washington's Current Landfill Regulations as an ARAR is
Unlawful and Inconsistent With State Practice." [3]
2.12.1 Additional Comment Under C.5.: The commentor states
that the current state of Washington Minimum Functional
Standards ("MFS") for landfill closure, codified at WAG
Chapter 173-304, are not relevant and appropriate
requirements for the Tulalip Site.
Response: EPA disagrees with the commentor's statement
that the current MFS for landfill closure are not
relevant and appropriate requirements for this interim
remedial action at the Tulalip Site. A detailed
discussion of the relevancy and appropriateness of
these regulations can be found in Section 11.2 of the
interim ROD. To summarize, the Tulalip Reservation is
surrounded on all sides by land which is under the
jurisdiction of Washington State. If the landfill were
located one mile south of its current location, outside
the Reservation boundaries, the MFS regulations would
be legally applicable if a cleanup action were
selected. However, Washington State regulations are
not applicable to this interim remedial action because
the landfill is located wholly within the boundary of
the Tulalip Indian Reservation, and under federal law
the laws of the state of Washington are not enforceable
within the boundaries of the Tulalip Indian
Reservation. The Tulalip Tribes have no landfill
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closure requirements that are comparable to state
landfill closure requirements; therefore, EPA has
determined that MFS shall be considered relevant and
appropriate to this interim remedial action, because
those state landfill closure requirements contain
provisions relating to landfill cover construction and
landfill gas control. The remedial action objectives
set out in the interim ROD require, among other things,
that the selected interim remedy "prevent direct and
skin contact with, and ingestion of, landfill contents
and contaminated soils, eliminate migration of leachate
that exceeds ambient marine water chronic criteria,"
and that the remedy "prevent inhalation and release of
landfill gas." The components of EPA's presumptive
remedy for municipal landfills (containment) include a
landfill cover. See OSWER Dir. No. 9355.0-49FS (EPA,
1992a, pg. 2.) The closure requirements of WAC 173-304
were meant to address problems or situations at
municipal solid waste landfill sites which are
sufficiently similar to those encountered at the
Tulalip Site (and identified as the remedial action
goals for the Tulalip Site), such that the use of the
WAC 173-304 closure requirements is well-suited to the
Tulalip Site. Thus, EPA has determined that the WAC
173-304 requirements for landfill covers are relevant
and appropriate to this interim remedial action at the
Tulalip Landfill Site. See also interim ROD Section
11.2 (which also identifies the federal landfill
closure requirements, codified at 40 C.F.R. § 258.60,
as an ARAR for this Site).
2.12.2 Additional Comment Under C.5.: The commentor also
states that the MFS requirements cannot be ARARs for
the Tulalip Site as those requirements apply only to
landfills which have closed after the effective date of
the regulations (November 3, 1988), and the commentor
believes that the Tulalip Landfill completed closure in
1979. The commentor also states that MFS cannot be an
ARAR for this Site because the State of Washington
never identified it as an ARAR, as is required by the
NCP.
Response: EPA disagrees with the commentor regarding
the status of the MFS as ARARs at the Tulalip Site. In
EPA's view, the selected alternative is a cost
effective interim containment action that is expected
to address effectively the ongoing discharges of
contaminants from the Site. The selected alternative,
4c - Geosynthetic Cover with Passive Drainage, is the
least expensive alternative that complies with
Washington State Minimum Functional Standards (MFS) for
landfill closures. As stated in the response above,
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EPA has determined that the MFS are relevant and
appropriate requirements for the Tulalip Landfill.
These standards are, as they are called, minimum
closure standards that have been established by the
State for proper landfill closure. An MFS cap has a
minimum number of low permeability layers (one), and
requires that the surface slopes of the cover to be
constructed at a grade not less than 2 percent. A two
percent grade is considered to be the minimum grade
necessary for adequate surface drainage.
An MFS cap is a relatively low cost cap, compared to
some types of caps that have been selected at other NPL
sites. At the Tacoma Landfill NPL site, for example, a
cap that complies with the requirements of the Resource
Conservation and Recovery Act (commonly referred to as
a "RCRA cap") was selected and constructed. RCRA caps
are considerably more expensive than MFS caps because
they require two impermeable layers instead of one.
Generally speaking, a RCRA cap will comply with MFS
requirements, but an MFS cap will not comply with RCRA.
RCRA requirements are more stringent.
While the Tulalip site closure may have been legal at
the time, and even accepted by EPA at the time, the
closure requirements at that time were not effective at
preventing the site from becoming a long term
environmental problem. This is evidenced by the data
collected during the 1988 site inspection and the RI/FS
data, which documented large volumes of contaminated
leachate leaving the site.
Since the Tulalip Landfill was closed, the State of
Washington (and EPA - see 40 C.F.R; Part 258) has made
the requirements for landfill closure significantly
more stringent. The State has acknowledged that the
previous landfill closure requirements were inadequate,
and recognized the need for improved closure standards
to help ensure that closed landfills would not threaten
human health and the environment. This appears to be
the case at Tulalip Landfill. Today, observing the
data that has been collected at the site after the 1979
closure, it is clear that the 1979 closure, believed
adequate at that time, was insufficient. This
'insufficiency may not have been apparent in 1979, and
it may not have been apparent when EPA agreed that the
landfill had been closed in accordance with the 1977
Consent Decree, but its insufficiency is apparent
today.
In addition, if one were to take the commentor's
argument regarding the applicability of the current MFS
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to the Tulalip Landfill to its logical conclusion, one
would have to conclude that the only laws that could be
ARARs at 'any Superfund site are those laws that were in
effect when a given site "ceased operations" and/or
"closed." Clearly, that was not what Congress intended
when it promulgated Section 121 of CERCLA. Congress'
intent under Section 121 of CERCLA was to have remedial
actions require the "level or standard of control for
such hazardous substance or pollutant or contaminant
which at least attains such legally applicable or
relevant and appropriate" requirements. See 42 U.S.C.
§ 9621(d)(2)(A). In the legislative history of Section
121, Congress also stated with regard to the issue of
"relevant and appropriate" environmental laws and Acts
that:
"[t]hese Acts need not be legally
applicable. The Administrator [of EPA]
is to look to the standards in all of
the acts which apply to a particular
release or a threatened release and
determine whether or not application of
the standards in the other acts is
reasonable and sensible under the
circumstances. In determining whether a
standard or criterion established under
any other Federal or state environmental
statute is applicable to cleanup of a
facility subject to a remedial action,
the Committee does not intend that such
standard or criterion should only be
applied where the "iurisdictional or
procedural requirements of such laws are
technically met. For example, the
regulatory requirements of the SDWA
apply only to certain specific sources
of public drinking-water. The Federal
Water Pollution Control Act [FWPCA] "-"""
contains similar procedural
restrictions. Nevertheless, the
Committee intends that all standards and
criteria developed under both statutes
shall apply to Superfund response —
actions when the bodies of water at
issue will be used for similar purposes
as those identified in the [SDWA], or
the [FWPCA], or where such bodies of
water present similar opportunities for
human exposure and adverse effects on
human health or the environment as are
presented by the environmental media
regulated under the other statutes."
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(Emphasis added). See House Comm. on
Public Works and Transportation,
Superfund Amendments of 1985, H.R. Rep.
No. 253, 99th Cong., 1st Sess., pt. 5,
at 54 (November 12, 1985). See, also,
40 C.F.R. § 300.5 (definition of
"relevant and appropriate requirements"
in the NCP).
Thus, it is clear that Congress intended that Federal
and state environmental laws such as the current State
of Washington MFS may be considered by EPA to be an
ARAR for the Tulalip Landfill Site, despite the fact
that the current MFS do not "technically" apply to the
Tulalip Landfill because it ceased operations in 1979.
Finally, EPA has determined that current MFS are
relevant and appropriate requirements for the Tulalip
Landfill interim remedial action because some of the
purposes of this interim remedial action (prevent
direct contact with the landfill contents and minimize
leachate generation) are similar to the purposes of the
MFS in WAC 173-304 (to prevent contact with landfill
contents after closure and to minimize and/or eliminate
generation of leachate). See, generally, WAC 173-304-
460 (2) (a), -460 (2) (c), and -460 (3) (a). The definition
of "relevant and appropriate requirements" in the NCP
states that a relevant and appropriate requirement is
one that:
"...while not 'applicable' to a
hazardous substance, pollutant,
contaminant, remedial action, location,
or other circumstance at a CERCLA site,
address problems or situations
sufficiently similar to those
encountered at the CERCLA site that
their use is well suited to the
particular site." 40 C.F'.R. § 300.5.
Thus, EPA has determined that the current MFS for
closure of landfills is well suited to the Tulalip
Site, as a MFS-compliant cover design would meet the
remedial action objectives for the Site.
The commentor's assertion that the State has not
identified MFS as an ARAR is without merit. The State
has no civil jurisdiction on the Tulalip Indian
Reservation, and therefore the State has no requirement
to identify ARARs for the Site because under federal
law the State law is not enforceable.
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2.12.3 Additional Comment Under C.4.: The commentor states
that the MFS are "action-specific" ARARs which become
ARARs only after a determination is made that a
landfill cover is necessary to protect human health and
the environment.
Response: EPA agrees that MFS are identified as
"action-specific" ARARs in the "CERCLA Compliance With
Other Laws" manual, but EPA disagrees with the
remainder of this comment. The potential ARARs for the
Tulalip Landfill Site were developed as part of the
ongoing RI/FS for the site. Since the Tulalip Landfill
is similar to a solid waste landfill in that the wastes
are heterogeneous and large in volume and thus
treatment of such wastes would be impracticable, and
EPA has determined that remedial action is necessary at
this site, it follows that federal and state laws
governing the proper closure of municipal landfills
would be potential ARARs for this site. As such, EPA
has identified the MFS under WAG Chapter 173-304 as an
ARAR in the interim ROD; Under Section 121 of CERCLA,
the MFS requirements apply to solid waste landfills on
the NPL located on land subject to the laws of the
state of Washington. However, since the Tulalip
Landfill is located on Tribal lands, the MFS
requirements are not applicable, but instead are
clearly relevant and appropriate specifications for
proper closure of this landfill. Since the MFS
regulations are ARARs for the Tulalip Landfill, if EPA
were to select an alternative which did not meet the
MFS requirements, EPA would have to waive the MFS ARAR
or find that the MFS are either not relevant or not
.....appropriate for this site. EPA guidance21 states:
"In the absence of Federal Subtitle D closure
regulations, State Subtitle D closure
requirements generally have governed CERCLA
response actions at municipal landfills as
applicable or relevant and appropriate
requirements (ARARs). New Federal Subtitle D
closure and post-closure care regulations
will be in effect on October 9, 1993 (56 Fed.
Reg. 50978 and 40 C.F.R. Part 258). State
closure requirements that are ARARs and that
are more stringent than the Federal
requirements must be attained or waived."
(Emphasis added).
21 Presumptive Remedy for CERCLA Municipal Landfill.Sites (EPA, 1993a,
page 7.)
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Both Federal Subtitle D closure regulations codified at
40 C.F.R. Part 258, and MFS for landfill closure
codified at WAC 173-304 have been identified in this
interim ROD as ARARs for the Tulalip Landfill.
2.12.4 Additional Comment Under C.5.: The commentor states
that Region 10's "arbitrary" application of the MFS
regulations as an ARAR is "highlighted" by recent
actions taken by the state of Washington at the Everett
Landfill/Tire Fire Site.
Response: EPA disagrees with the commentor that EPA
has "arbitrarily" applied any ARARs at the Tulalip
Landfill Site. In comparing the Everett Landfill to
the Tulalip Landfill, the commentor fails to recognize
that the Everett Landfill is not on the NPL. The
Tulalip Landfill is on the NPL, and therefore EPA must
follow CERCLA and the NCP when investigating the site
and developing remedial alternatives. Section 121 of
CERCLA states that the remedial action selected for a
' given site must attain the standards set out in state
environmental laws that are more stringent than federal
law. However, the only standards which can legally be
ARARs under Section 121 are those standards which are
"promulgated" at the time the remedial action is
selected. Thus, EPA cannot consider (as suggested by
the commentor when he proffers the Everett Landfill as
a comparison) the old MFS, which were codified at WAC
173-301, as these regulations are no longer in effect
and in 1985 were superseded by the WAC 173-304
regulations.
In addition, Section 300.5 of the NCP defines "relevant
and appropriate requirements" to be those state
standards that are identified in a timely manner and
which "are more stringent than federal requirements."
See 40 C.F.R. § 300.5. The old landfill closure
requirements generally called- for the installation of a
cover that consisted of approximately 2 feet of^soil
with adequate drainage. The current federal municipal
landfill requirements (codified at 40 C.F.R. Part 258)
regarding solid waste landfill cover requirements for
closure require, inter alia, a landfill cover with a
permeability less than or equal to the permeability of
any bottom liner system or natural subsoils present, or
a permeability no greater than IxlO"5 cm/sec, whichever
is less. Therefore, since the WAC 173-301 closure
requirements are less stringent than the current
federal municipal landfill closure requirements, EPA
cannot consider the old, less-stringent WAC 173-301
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requirements as ARARs when making remedial action
decisions at the Tulalip Landfill Site.
2.13 Comment: "C.6. Region 10's Proposed Plan Capriciously
Mischaracterizes the Site's Environs." [3]
Response: EPA disagrees with the commentor. The AR
contains an abundance of information indicating that
the wetlands surrounding the landfill are of great
ecological significance. The "Shoreline of Statewide
Significance" and the "AMBS" designations are not the
sole reasons upon which EPA is basing the selected
interim remedy. Rather, these designations, in
combination with other information provided in the AR,
reflect the importance of the surrounding areas. It is
important to realize that the potential impacts of the
landfill leachate discharges are not limited to the
immediate area surrounding the landfill.
Contaminants from the landfill flow into Ebey and
Steamboat Sloughs, and then into Puget Sound. The
Puget Sound estuary, which includes the Tulalip
Landfill, is an estuary of national significance.
Puget Sound is one of 28 estuaries in the United States
that are currently part of the National Estuary Program
(NEP), which was established under the Clean Water Act.
The NEP's mission is to protect and restore the health
of estuaries while supporting economic and recreational
activities. An EPA document entitled "National Estuary
Program: Bringing Our Estuaries New Life"
(EPA/842/F/93/002) defines an estuary, explains the
significance of estuaries, and provides some
information on some of the problems of estuaries in the
program. The following is excerpted from the document:
"WHAT IS AN ESTUARY?
An estuary is a coastal area where fresh water
from rivers and streams mixes with salt water from
the ocean. Many bays, sounds, and lagoons along
coasts are estuaries. Portions of rivers and
streams connected to estuaries are also considered
part of the estuary. The land area from which
fresh water drains into the estuary is its
watershed.
WHY ARE ESTUARIES SIGNIFICANT?
Estuaries are significant to both marine life and
people. They are critical for the survival of
fish, birds, and other wildlife because they
provide safe spawning grounds and nurseries.
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Marshes and other vegetation in the estuaries protect
marine life and water quality by filtering sediment and
pollution. They also provide barriers against damaging
storm waves and floods.
Estuaries also have economic, recreational, and
aesthetic value. People love water sports and
visit estuaries to boat, fish, swim, and just
enjoy their beauty. As a result, the economy of
many coastal area is based primarily on the
natural beauty and bounty of their estuaries.
Estuaries often have ports serving shipping,
transportation, and industry. Healthy estuaries
support profitable commercial fisheries. In fact,
almost 31 percent of the Gross National Product is
produced in coastal counties. This relationship
between plants, animals, and humans makes up an
estuary's ecosystem. When its components are in
balance, plant and animal life flourishes.
Because of our love of water, almost half of the
United States population now lives in coastal
areas, including the shores of estuaries. In
addition, coastal counties are growing three times
faster than anywhere else. Unfortunately, this
increasing concentrationr-of people upsets the
balance of the ecosystems. People need housing,
services, and roads, so new industry and
businesses arrive to provide them. All this
stresses the estuaries by increasing the types and
amounts of pollution entering them. When severe,
such stresses have forced government authorities
to close beaches and shellfish beds and issue
warnings about eating fish. In addition, removing
grass and trees for development can cause soil
erosion and reduce natural habitat, which
contributes to the threat of extinction of
endangered wildlife."
"PUGET SOUND:
Protecting the Sound from Contaminated Sediments
Sediments in Puget Sound are contaminated with
toxic chemicals. This contamination results from
large inputs of toxic substances to a body of
water, which is a very serious problem in
estuaries. Marine animals that live on the
estuary floor can accumulate the poisons in their
bodies and, sometimes, pass them on to humans who
can eat them. To protect marine life and help
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guide decisions on when and where to clean up
contaminated sediments, the Puget Sound NEP's CCMP
called for development of the nation's first
marine sediment standards . Because industrial and
sewage plant dischargers are among the main
sources of toxic substances entering the Sound,
these sediment standards are being incorporated
into their discharge permits. This should
significantly reduce the quantity of poisonous
substances entering the Sound."
This EPA document recognizes that contaminated
sediments are a problem in Puget Sound, and that this
contamination is a result of inputs of toxic
substances. The RI/FS data clearly indicate that the
Tulalip Landfill is a chronic source of contaminants to
the surrounding environment. The landfill, by
definition, is located within the Puget Sound estuary,
and according to the RI/FS, all of the leachate
discharges from the landfill end up in this estuary.
EPA concludes that leachate discharges from the
landfill are contributing to the loading of
contaminants in the Puget Sound estuary,22 and the
selected interim remedial action is necessary to
contain these contaminants and prevent them from
migrating into surface waters where they can interact
with the environment. Clearly, there are other
contaminant sources that are also contributing to
contamination of the estuary. However, determining the
relative contributions of various sources to the
estuary is outside the scope of CERCLA, and addressing
those sources of contamination are outside the scope of
this response action. By implementing the selected
alternative, contaminant loading to the estuary will be
reduced.
2.14 Comment: "C.7. Region 10's Preferred R^ne^y^ is
Inconsistent with Actions Taken at Similar Sites in
Region 10 and Elsewhere." [3]
Response: EPA disagrees with this comment. The On-
Source Area of the Tulalip Landfill is being managed
and evaluated pursuant to EPA' s presumptive remedy
process. As noted in EPA's memorandum Presumptive
Remedies and NCP Compliance, (EPA, 1995a) "(t)he use of
presumptive remedies advances the NCP remedy-selection
objectives in that the presumptive remedy initiative
~ Contaminant loading caused by Tulalip Landfill leachate discharges is
contained in Table 5-14 of the Remedial Investigation Report.
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promotes consistency in decisionmaking." The reader is
referred to Responses to Comments 2.1.2 and 2.2 for
more information regarding presumptive remedies and
remedy selection. The nine remedy selection criteria
in the NCP ensures the consistency noted in the above
memorandum. The presumptive remedy process in general,
and as used at the Tulalip Site, incorporates the nine
NCP remedy selection criteria and provides additional
consistency in decision-making.
The nine criteria were developed as a means to ensure
consistency because the Agency understood that direct
site-to-site comparison as a means of determining
remedies was not feasible. The facts that form the
basis for a remedy are unique to each site. There are
a number of factors, in addition to the use of a
presumptive remedy process, that make the comparison of
the evaluation and decisionmaking processes between
sites inappropriate, such as: (1) the impact of state
ARARs: (2) laws, regulations, and policies in place at
the time of the remedial action; (3) the lead agency
(federal or state) in charge of the cleanup action; (4)
terms and conditions negotiated between the lead agency
and the parties conducting the cleanup; and (5) unique
site characteristics. Comparison of decisions and
actions at sites has never been a requirement of the
CERCLA remedy selection process because of the inherent
variations that exist among sites.
Because the presumptive remedy process was used for the
on-source area of the Tulalip Site and was not used at
any of the sites noted by the commentor, comparison of
risk .evaluation processes (e.g., risk assessment
approaches, remedy selection) is inappropriate. The
presumptive remedy process specifies the use of a
streamlined risk assessment, as appropriate, for
evaluating the need for remedial action at a site.
The presumptive remedy process is a streamlined version
of the full scale remedy investigation and
implementation process used at the other sites.
Consequently, differences between the evaluations
exist.
EPA notes that EPA's selected interim remedy for the
source area of the Tulalip Landfill, which includes a
low permeability cover, is, in general, consistent with
remedies at the 30 sites EPA evaluated in developing
the presumptive remedy approach and guidance. Of the
30 sites EPA examined, 24 sites, or 80% selected some
type of low permeability cover as a remedy for the
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source area of the landfill. See OSWER Dir. No.
9355.0-49FS (EPA, 1993a). See also Responses to
Comments 8.5 and 8.6.
2.15 Comment: "D. Application of EPA's Presumptive Remedy
Guidance Does Not Require an Impermeable Cap for the
Tulalip Landfill." [3]
Response: EPA agrees that the Presumptive Remedy
guidance calls for containment of landfill wastes as
the presumptive remedy for Municipal Landfill Sites.
The guidance describes landfill caps as one possible
component of the containment presumptive remedy. As
such, EPA evaluated all of the components of the
presumptive remedy of containment, including a capping
alternative, when EPA made its remedial decision in the
interim ROD. See also Response to Comment 8.1.
EPA has been receptive to non-capping alternatives
suggested by the Respondents, and has done its best to
evaluate these alternatives thoroughly. EPA's analysis
of the alternatives in the ROD has led EPA to the
conclusion that Alternative 4c is most likely to
provide adequate protection at the most reasonable
cost. None of the non-capping alternatives suggested
by the Respondents provide a better balance of trade-
offs than Alternative 4c. More specifically, there are
many significant uncertainties associated with
Alternatives 2b and 2b(ii) regarding their potential
protectiveness, implementability, and cost that are not
- • exhibited by Alternative 4c.
2.16 Comment: "E. The Leachate Collection and Treatment
Alternative (2b) is Preferable to the Geosynthetic
Cover with Passive Drainage Alternative (4c) Based on
the NCP's'Remedy Selection Criteria." [3] [17]
Response: EPA evaluated eleven alternatives in the
ROD, including Alternative 4c - Geosynthetic Cover with
Passive Drainage; Alternative 2b - Leachate Collection
with Treatment Berm; and Alternative 2b(ii) - Leachate
Seep Collection with Discharge to POTW. EPA's
analysis, provided in the ROD, shows that neither
Alternative 2b nor 2b(ii) pass the two "threshold
criteria" that must be met in order to further consider
an alternative against the other seven NCP criteria.
Appendix A to the ROD explains that even when evaluated
against the NCP balancing criteria, Alternatives 2b and
2b(ii) compare poorly relative to the selected
Alternative 4c.
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EPA concludes in the ROD that, based on EPA's analysis
of all the alternatives that were considered,
Alternative 4c provides the best balance of trade-offs
among the alternatives with respect to the NCP remedy
selection criteria. Of all the alternatives considered
by EPA, Alternative 4c is the least expensive
containment alternative that will effectively stem the
generation and flow of contaminated leachate into the
surface waters surrounding the landfill. EPA's
analysis provides sound reasons why alternative 4c was
selected and other alternatives were not.
EPA disagrees with the Respondents' analysis, and the
Respondents' conclusions based on their analysis, which
attempts to compare Alternative 2b(ii) with Alternative
4c with respect to the nine NCP criteria (Colder,
1995b.) In EPA's view, the Respondents' analysis fails
to fully and fairly describe the concerns with
Alternative 2b(ii). More specifically, the
Respondents' evaluation of Alternative 2b unjustifiably
overestimates the potential effectiveness of this
unproven alternative, disregards potentially serious
problems with regard to its implementability, and,
based on the considerable uncertainties that EPA
perceives with respect to this alternative's unproven
technologies, significantly underestimates the likely
cost of construction and operation and maintenance
(O&M) of the proposed system.
EPA has been receptive to non-capping alternatives
suggested by the Respondents, and has evaluated non-
capping alternatives. Because EPA may end up
implementing this interim containment remedy if an
agreement cannot be reached that provides for the PRPs
to do the work,.it is in EPA's best interest, as well
as the Respondents', to select an interim remedy that
is most likely to provide adequate protection of human
health and the environment at the most reasonable cost.
In EPA's view, it is not cost-effective to invest
millions of dollars in constructing Alternatives 2b and
2b(ii), unproven technologies that would not be
protective, not comply with ARARs, might be
implementable, and are more costly to operate and
maintain than Alternative 4c, which employs proven
containment technology with known effectiveness,
implementability, reliability, is protective of human
health and the environment, complies with ARARs, and
has lower operations and maintenance costs.
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EPA's careful and thorough analysis of the alternatives
described in this ROD leads EPA to the conclusion that
Alternative 4c is the most appropriate interim remedy.
The other 'alternatives simply do not provide a better
balance of trade-offs with regard to the nine NCP
criteria than Alternative 4c. Based on EPA's analysis,
EPA selected Alternative 4c as the interim remedial
action, in accordance with CERCLA, the NCP, and EPA
guidance.
2.17 Comment: "F. The United States Senate Has Directed
EPA to Undertake Actions at the Tulalip Landfill Which
Require Region 10 to Withdraw the Proposed Plan
Immediately." [2] [3] [8] [18]
Response: EPA disagrees with the conclusion of this
comment. The language the commentor refers to is
contained in the United States Senate Appropriations
•,_ Committee Report that accompanied the HUD and
Independent Agencies Fiscal Year 1996 Appropriations
Bill. This funding bill has not been signed into law
by President Clinton and therefore is not in effect.
EPA is currently conducting a comprehensive baseline
risk assessment for the Site to support selection of a
final remedial action at the Site. EPA expects the
comprehensive baseline risk assessment may be completed
in the summer of 1996. The comprehensive baseline risk
assessment will be used to evaluate whether additional
cleanup measures should be undertaken in the off-source
areas to address contamination that has migrated to
these areas from the landfill. A comprehensive
baseline risk assessment is not necessary to develop
early or interim alternatives for the source area of
the landfill, nor would it allow development and
evaluation of less expensive containment alternatives
for the source area. "*~
In addition, EPA notes that after the CERCLA statute is
amended or an appropriations bill is signed into law,
the Agency will review its requirements and make any
appropriate changes in the way the Superfund program is
being managed at all CERCLA sites, including the
Tulalip Landfill Site. Also, the Agency at present
cannot make any predictions regarding the EPA budget
directives or anticipate what the final budget will be,
how monies will be allocated for what actions, or what
the provisions of a revised Superfund law will require.
As such, EPA Region 10 believes it would be
inappropriate to make changes to the Tulalip Landfill
Site decision-making process until these legislative
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changes are codified into law. For the present, the
Region is proceeding with this interim remedial action
based on current laws, regulations, and policies.
2.18 Comment: Commentor stated that the Tulalip Site is
being investigated under the NCP and it is therefore
not appropriate to use additional concepts applied
under other programs, such as pollution prevention, to
address the site. [2]
Response: The commentor appears to be focusing his
comment on the statement made by Mr. Brian O'Neal, a
technical consultant for The Tulalip Tribes, at the
October 3, 1995 public meeting on the Proposed Plan for
the Tulalip Landfill site. In discussing the
appropriateness of the placement of a cap on the
landfill, Mr. O'Neal drew an "analogy between the use
of the EPA's pollution prevention program" and the
selection of the cap. Mr. O'Neal's comment did not
state that the cap was selected because of EPA's
pollution prevention goals. The fact that the
implementation of a cap may result in minimization of
leachate production, and this reduction of leachate is
consistent with the philosophy of pollution prevention,
does not mean that EPA's selection of the cap was
driven by the pollution prevention program. Rather,
EPA's selection of a cap at the Tulalip Landfill was
governed by CERCLA, the NCP, and EPA guidance.
2.19 Comment: Commentor"stated that it would be prudent and
good public relations for EPA to back off of
settlements at this time, especially in light of
impending legislation focused at removing the Tulalip
Landfill from NPL listing. [2]
Response: EPA presumes that the commentor is referring
to the de minimis settlements since no other settlement
offers are currently available. EPA believes that
offering settlement opportunities to de minimis parties
is entirely appropriate and consistent with current EPA
policy. EPA is allowing these parties to obtain a
complete release from liability at the Site at a very
early stage in the process. With respect to the
portion of the comment regarding "impending
legislation," EPA assumes that the commentor is
referring to language in the United States Senate
Appropriations Committee Report for the HUD and
Independent Agencies Fiscal Year 1996 Appropriations
Bill. The proposed report language would not require
EPA to remove the Tulalip Landfill from the NPL;
rather, the language directs EPA to conduct a
comprehensive baseline risk assessment prior to
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selecting a final remedy. Despite the fact that the
funding bill has not become law, EPA is proceeding at
the Site.in a manner consistent with this language. A
comprehensive baseline risk assessment will be
completed prior to the selection of a final remedy
which addresses site-wide contamination. EPA is aware
of no impending legislation focused on removing the
Tulalip Landfill from the NPL.
EPA notes, for further clarification, that some Tulalip
PRPs have initiated a lawsuit in federal court that
challenges EPA's listing of the Site on the National
Priorities List. EPA is unable to comment further on
the lawsuit because this litigation is pending. See
also Response to Comment 4.1.
2.20 Comment: Commentor stated that the AOC was intended
only to cover the conduct of remedial investigation and
feasibility studies and that it did not bind the
respondents into performing remedial action at the
site. [2]
Response: EPA agrees with this comment. However, EPA
notes that the RI/FS AOC does not provide a release
from liability for the signatories to the AOC. The
PRPs who signed the AOC remain potentially liable for
any future costs related to any response actions at the
Site.
2.21 Comment: Commentor asked who would be expected to pay
for the long-term maintenance associated with an
FML-type cap if it were installed at the landfill. [2]
Response: EPA expects to include, as part of
settlement terms reached with PRPs in the future,
requirements for the long-term maintenance associated
with the selected interim remedy. Pursuant to Section
107 of CERCLA, 42 U.S.C. § 9607, PRPs are liable for
the response costs associated with the site clean-ups.
The costs of long-term maintenance fall within the
definition of response costs and are, therefore, the
responsibility of the PRPs.
2.22 Comment: Commentor asked whether the EPA legally
maintains authority over future development at the site
given that the property is situated on the Tulalip
Indian Reservation. [1]
Response: Pursuant to CERCLA, EPA has authority to
take response actions to protect public health or
welfare or the environment. Consistent with this
authority, EPA has selected a remedy which addresses
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potential or existing threats associated with the
landfill located on the reservation. EPA's selected
remedy may have an impact on future land development at
the Site. As part of the remedial action, EPA will
require institutional controls which will protect the
integrity of the implemented remedy. EPA and the Tribe
will develop a plan for "routine" future uses of the
Site. This plan will also protect the remedy. See ROD
Section 10.0 - Selected Remedy, for more information
about institutional controls. See also Response to
Comment 2.7.2.
2.23 Comment: Comraentor asked if off-site wetlands that
revealed contamination similar to what was found at the
landfill would also become the responsibility of the
PRPs. [1]
Response: The PRPs are potentially responsible for
contamination at the Site. The extent of contamination
at the Site includes the contaminant source area (i.e.,
the 147-acre ;landfill area, including the perimeter
landfill berm), and any off-source areas that have been
contaminated by discharges from the source area. Such
contaminated off-source areas are part of the Site.
The Site-wide FS, which has not yet been completed,
will evaluate alternatives, including a "no-action"
alternative, for cleaning up any contaminated off-
source areas.
2.24 Comment: Commentor asked for clarification in meaning
between the "Interim Cleanup Action" and the "Final
Cleanup Action." [1]
Response: The interim cleanup action is an early,
interim remedial action that EPA believes must be
implemented at this time to contain the waste at the.
Site in order to protect human health and the
environment. EPA expects that this interim remedial
action will minimize the migration of contaminants from
the source area to off-source wetlands, sloughs, and
tidal channels. If, after construction of the selected
interim remedial action (Alternative 4c) is completed,
EPA determines, based on Site data, that Alternative 4c
is not effectively containing the landfill wastes,
additional containment action(s) for the source area,
such as a perimeter leachate collection and treatment
system, may be necessary. If such additional measures
are necessary, they will be documented in the final ROD
for the Tulalip Site, which will address any additional
measures for the source area, as well as any remedial
actions that may be necessary for the off-source areas
of the site (such as cleanup measures for the off-
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source wetlands, if necessary). For additional
information, see interim ROD Section 4 - Scope and Role
of Interim Response Action.
2.25 Comment: Commentor states that EPA's Presumptive
Remedy Guidance assumes institutional controls will be
necessary to restrict future activities at CERCLA
municipal landfills in order to maintain the integrity
of the containment system. The commentor states that
EPA has ignored this fact by using the off-source media
to justify a remedy that can only be applied to on-
source media. [3]
Response: The commentor is inappropriately linking
concepts that are not related in the way the commentor
suggests. EPA agrees that the Presumptive Remedy
Guidance states that institutional controls are
appropriate to restrict future activities at CERCLA
municipal landfills in order to maintain the integrity
of the containment system. For example, an. appropriate
institutional control might be a prohibition on
excavating holes through a landfill cover system,
because holes would obviously reduce the effectiveness
of the cover. However, such institutional controls
have nothing to do with EPA's consideration of off-site
data in the context of selecting a containment remedy
for the-source area.
It is entirely appropriate to consider off-site data
(along with on-source data) when evaluating the
potential need for an interim containment action at
landfill sites because the basic goal of a containment
action ITS to contain the landfill wastes, thereby
reducing impacts of contaminants migrating from the
source area to the off-source area. For this reason,
in EPA's view, it would be difficult to make a sound
decision on whether containment of a source area is
needed in the absence of any off-source data. In fact,
EPA's review of the RI data indicates that, at this
time, the landfill wastes are not adequately contained;
the RI data shows that the landfill is acting as a
contaminant source, and contaminants are migrating from
the landfill to off-source areas. The Streamlined Risk
Assessment included an evaluation of off-source data to
comparison numbers that are considered to be protective
of human health and the environment, and found many
exceedances of the comparison numbers, which indicated
that the landfill poses a potential threat to the
surrounding areas. A containment remedy would contain
these contaminants and prevent on-source contaminants
from moving to off-source areas, thereby reducing
potential risks to humans and ecological receptors. If
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the off-source data had showed no exceedances of the
comparison numbers (which is not the case), EPA may
have concluded that the landfill is not acting as a
contaminant source to off-source areas.23
EPA is unclear as to the meaning of the commentor's
reference to institutional controls as related to the
off-source area. Consideration of off-source data
during the interim remedy selection process is
unrelated to the issue of institutional controls which,
in the case of a solid waste landfill cover, are
usually identified along with the selected remedy in
the ROD to protect the integrity of the cover system
after it is installed.
2.26 Comment: Commentor stated for the public record that
the Seattle Disposal Company (SDC) previously requested
an emergency injunctive motion for relief from the 9th
Circuit and argued at the time that irreparable and
immediate threat was present at the site. Commentor
went on to state that now that the SDC is considered a
viable PRP, they argue that risks at the site need to
be evaluated before a remedy is selected, if a remedy
is warranted at all. [2]
Response: Comment noted.
2.27 Comment: EPA's proposed remedy is not mandated by
other environmental laws or standards and goes well
beyond the "threshold criteria" of the NCP. [3]
Response: It is EPA's responsibility to fulfill the
statutory mandates of all federal laws under its
jurisdiction. CERCLA is just one of many laws which
authorize EPA to respond to environmental problems.
Since CERCLA and the NCP specifically govern response
actions at sites where there has been a release- or
threatened release of hazardous substances which may
present an imminent and substantial endangerment to
public health or the environment, EPA is required to
select a remedy which is consistent with the
requirements set forth in CERCLA and the NCP,
regardless of whether the remedy chosen is "mandated"
by other environmental laws or standards. Although
other laws and regulations may be ARARs at the Site,
and therefore may be considered in selecting a remedy,
only CERCLA specifically governs the selection of
response actions at CERCLA sites. EPA believes it has
23 On-source data must also be considered, because another purpose of a
containment remedy is to prevent direct exposure to landfill contents.
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conducted a thorough evaluation of alternatives through
the use of the nine NCP criteria. EPA is confident
that the.remedy it has selected is the most appropriate
to remediate the source area of the Site, and directs
the commentor to ROD Section 9.0 - Summary of the
Comparative Analysis of Alternatives, for further
information regarding EPA's evaluation.
3.0 PRE-CERCLA CLOSURE HISTORY
3.1 Comment: Commentor asked if EPA approved the closure
of the Tulalip Landfill in 1979 and 1980 after the
cover was placed. [2]
Response: At the insistence of EPA, the landfill was
closed and capped in 1979 pursuant to the Rivers and
Harbors Act of 1899, 33 U.S.C. §§ 403,407 and the Clean
Water Act, 33 U.S.C. §§ 1311, 1319,1342, and 1344.
The closure and capping was performed in accordance
with a consent decree, which was executed by EPA,
Seattle Disposal Company and the Tulalip Tribes and
entered in the U.S. District Court for the Western
District of Washington. However, the filling and
initial capping of the landfill as provided in the
consent decree, while completed and approved in 1979,
failed to halt the discharge of contaminated leachate
from the landfill. As a result, further remediation of
the landfill is necessary at this time. The current
PRPs at the Site did not receive a complete release
from future liability at the Site through the 1979
consent decree, therefore they are still responsible
for the response costs under CERCLA to address ongoing
. problems at the Site.
3.2 Comment: Commentor asked why, if the original closure
and containment of the landfill was accepted in 1979,
PRPs are now being asked to address problems at the
site. [1] [12]
Response: The PRPs are being asked to address problems
at the Site because the original closure and
containment of the landfill did not successfully
eliminate the production and discharge of hazardous
substances from the Landfill into the environment.
3.3 Comment: Commentor indicated that EPA had required
Marine Disposal to cover the landfill with two feet of
clean fill and that EPA had inspected and accepted the
completed cover. The commentor indicated that EPA
should honor its release and that pre-1979 parties
should have no further liability. [2]
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Response: Marine Disposal was required to comply with
all existing regulations governing the capping of a
landfill.' Included in those requirements were the
state MFS which, consistent with technical knowledge of
capping technology at the time, dictated placing two
feet of clean fill on the landfill as part of the
capping effort. CERCLA is a strict liability statute
which means that a person can be held liable for costs
of cleanup regardless of fault. Despite efforts to
cover the Site in 1979, which were consistent with
current laws and regulations at that time, the cap
installed at the time was ineffectual in remediating
the contaminant problem at the Site. No PRPs were
given a complete release from liability under the
Consent Decree for their contribution to the
remediation of the Site at that time. Thus, Marine
Disposal Company remains liable for the costs of
remediating the Site according to current laws and
regulations.
3.4 Comment: Commentor indicated that the Tulalip Tribes,
with the permission of EPA, reopened the landfill in
1986 to accept demolition debris and in doing so,
disturbed the cover. The commentor stated that the
Tulalip Tribes should continue to develop the site as
originally intended and that it is not EPA's
responsibility to continue this development or
compensate the Tulalip Tribes for loss of natural
resource land which the Tulalip Tribes elected to fill.
[2]
Response: EPA's responsibility is to respond to the
release of hazardous substances into the environment.
Leachate containing hazardous substances continues to
be generated and released from the landfill. EPA has
the authority under CERCLA to require any persons who
are defined as potentially liable parties under Section
107 of CERCLA, 42 U.S.C. 9607, to pay for the costs of
responding to that release. Additionally, EPA has no
evidence that the acceptance of demolition debris for
the purpose of building roads on the landfill as part
of a capping effort to address ongoing leachate
discharges disturbed the cover of the landfill.
3.5 Comment: Commentor asked why EPA, if they are
concerned with remediating leachate discharges under
Superfund, allowed the Tulalip tribes to violate their
NPDES permit since at least 1986. Also EPA allowed
toxic dumping to be done after the site was legally
closed. [2] [8]
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Response: As stated in Response to Comment 2.8.1.,
EPA's obligation to take enforcement action for
violation of NPDES permits is wholly discretionary.
EPA has determined at this time that the appropriate
means of addressing the leachate problem at the Site is
not through enforcement of the NPDES permit, but
rather, through the remedy selection process under
CERCLA. Under CERCLA, EPA can require extensive study
of the Site and can evaluate a number of alternatives
for remediation of the Site so that it can choose a
response action which most comprehensively and
effectively addressees the contamination.
EPA did not allow toxic dumping to be done after the
Site was legally closed. In 1986, the Tribes applied
for an NPDES permit solely for the purpose of placing
additional capping material on the landfill to correct
the previous inadequate closure of the landfill. The
original permit allowed the Tribes to obtain low
permeability soil from a freeway construction project
near Seattle. However, the soil did not become
available and EPA modified the NPDES permit in 1987 to
allow placement of capping materials from other
sources. The permit contained provisions which
required the sources of capping material to be screened
for hazardous substances prior to their placement on
the landfill. Due to problems in obtaining adequate
types and amounts of capping material, only a small
portion of the capping volume approved by EPA was
actually placed at the Site. The Tribe's limited
capping activities at the Site from 1987-1990 resulted
primarily in construction of a grid of roadways rather
than the corrective capping envisioned. EPA is not
aware of any information which indicates that any
hazardous substances have been transported to the Site
since 1979.
4.0 NPL LISTING
4.1 Comment: Commentor suggested that the rationale
employed in classifying the site as a Superfund site
was flawed and required further explanation. [1]
Response: On April 25, 1995, EPA promulgated .a final
rule adding the Tulalip Landfill site to the National
Priorities List (NPL) (60 Fed. Reg. 20330). The site
had been proposed for inclusion on the NPL on July 29,
1991 (56 Fed. Reg. 35840). The rationale employed in
classifying the site as a Superfund site is based on
the criteria in the Hazard Ranking System (HRS)
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established by the National Contingency Plan, 40
C.F.R., Part 300 under Section 105(a)(8)(B) of CERCLA,
as amended.
EPA received few comments on the proposal during the 60
day public comment period. However, voluminous late
comments were received by EPA from some of the PRPs
well after the close of the comment period. EPA
carefully evaluated all comments received prior to the
final listing decision and specifically responded to
the claim by some commentors that its rationale was
"flawed". This response can be found in the Support
Document for the Revised National Priorities List Final
Rule-April 1995 (EPA, 1995b).
EPA has followed all of the Administrative Procedures
Act requirements that govern this informal rule-making
as well as the specific criteria for listing a site on
the NPL established by regulation.
5.0 TRIBES ROLE
5.1 Comment: Commentor asked what settlement amount is
being offered to the Tulalip tribe as their portion of
the responsibility for the site contamination, and what
things they are being required to do to take care of
the cleanup. [2]
Response: The Tulalip Section 17 Corporation24, U.S.
Bureau of Indian Affairs, generators, transporters, and
users of the site are currently participating in a cost
allocation process. The purpose of this process is to
determine the fair share of response costs that each of
the parties should pay. EPA intends to discuss
settlement terms with parties after the conclusion of
the allocation process.
5.2 Comment: The commentor stated that the Tribes should
have to pay for the entire cleanup. They were paid for
use of the landfill. The Tribe caused the problem.
[9] [15] [17]
Response: Pursuant to CERCLA, owners and operators of
the Site as well as generators and transporters of
hazardous substances found at a Superfund Site are
liable for cleanup costs associated with a site.
24 The Tulalip Section 17 Corporation leased the Site to the Seattle
Disposal Company for landfill operations and was also involved in post-1980
capping activities at the Site.
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Therefore, other parties in addition to the Tulalip
Section 17 Corporation, are responsible for response
costs incurred at the Site.
5.3 Comment: Commentor asked if the participation of the
Tulalip Tribes' representatives at the October 3 public
meeting was funded by EPA under a specific cooperative
arrangement. [2]
Response: The Tribes' participation, including Tribal
members, the Tribes' Superfund Coordinator and
technical consultants, at the Public meetings held by
EPA on August 22, 1995 and October 2, 1995 was not
funded by EPA. However, EPA notes that, to assist the
Tribes' involvement in the Superfund process, EPA
entered in to a Memorandum of Agreement (MOA) with the
Tribes on February 11, 1992. The MOA was amended on
September 9, 1992 to include the Bureau of Indian
Affairs as a signatory. EPA also granted the Tribes a
Superfund support agency cooperative agreement under
Section 104 of CERCLA, which continues to provide funds
for the Tribes' Superfund coordinator.
6.0 ARARS
6.1 Comment: Commentor asked for an explanation of how EPA
could consider MFS as ARARs for this site and what
efforts EPA has made to determine how Department of
Ecology has applied current MFS to landfills that were
closed before those standards were adopted. [2]
Response: See the Responses to Comments 2.12., 2.. 12.1,
2.12.2, 2.12.3 and 2.12.4 regarding the applicability
of MFS as an ARAR for the Tulalip site.
EPA, in accordance with the EPA/Ecology Memorandum of
Understanding of August 18, 199425, has provided
Ecology with periodic updates regarding past and
projected activities at the Tulalip site.
25 Environmental Protection Agency, Region 10, Washington State
Department of Ecology, Superfund management in Washington, August 18, 1994
describes the role EPA and Ecology will play at each NPL site in the State of
Washington.
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According to Mr. Pete Kmet26, Senior Environmental
Engineer, Toxics Cleanup Program, Washington Department
of Ecology, the current MFS are required at all solid
waste landfills requiring remedial action under MTCA.
regardless of the date that the landfill was closed.
WAC-173-340-710(6)(c) states:
"Solid waste landfill closure requirement. For
solid waste landfills, the solid waste closure
requirements in chapter 173-304 WAC shall be
minimum requirements for cleanup actions conducted
under this chapter. In addition, when the
department determines that the closure
requirements in chapter 173-303 WAC are applicable
requirements, the more stringent closure
requirements under that law shall also apply to
cleanup actions conducted under this chapter."
7.0 HR 2099
7.1 Comment: Commentor asked EPA if it plans to follow the
direction of the Senate and if it plans to undertake an
alternative dispute resolution process which involves a
neutral party. The commentor also indicated that the
public meeting directed by a neutral facilitator does
not constitute a neutral party dispute resolution
process as defined by the U.S. Senate. [2]
Response: EPA will address any pending legislation
when it becomes final. See Responses to Comments 2.6
and 2.17.
8.0 CONSISTENCY WITH OTHER SITES
8.1 Comment: Commentor stated that they did not believe
that the presumptive remedy was synonymous with an
impervious cap, and that of 30 sites which went into a
documented presumptive remedy, only 24 had low
permeability caps. [2]
Response: EPA agrees that the presumptive remedy is
not "synonymous" with an impervious cap and that the
presumptive remedy specifies containment as the
presumptive remedy for municipal landfills. For
26 Personal communication by Lynda Priddy on February 15, 1996.. Mr. Kmet
cited WAC 173-340-710(6) (c) as applicable to all solid waste landfills,
regardless of the landfill closure data (if any), determined to require a
remedial action pursuant to MTCA.
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further details, see the Response to Comments 2.7.1 and
2.15. According to EPA's Guidance "Presumptive Remedy
for CERCLA Municipal Landfill Sites" (EPA, 1993a)
components of containment include features such as a
cap, groundwater controls, leachate collection and
treatment, gas collection and treatment, etc.
EPA also agrees that 24 of the 30 or 80% of the sites
studied as background for the presumptive remedy had an
low permeability cap. EPA notes that all 30 sites
either already had a cover, or the ROD called for
repairs of an existing cover, or the ROD called for
construction of a new cover.
In EPA's memorandum "Presumptive Remedies and NCP
Compliance" (EPA, 1995a) the Agency notes that
flexibility is also needed to take into account unique
site characteristics. EPA agrees that the presumptive
remedy does not dictate a cover and based on EPA's
experience other alternatives are sometimes selected.
Unique site characteristics can lead the Agency to
select different remedies at seemingly similar sites.
The reason Alternative 4c, which is a geosynthetic cap,
has been chosen for the Tulalip Site is that
Alternative 4c satisfies all of the NCP remedy
selection criteria EPA uses to .evaluate remedial
alternatives. Other remedial alternatives, some of
which include only a leachate collection system without
a cap, were also evaluated according to the same NCP
criteria and failed to satisfy EPA's remedy selection
criteria. For more information about the remedy
selection process and evaluation used for remedial
alternatives, see the Response to Comment 1.1, and ROD
Section 9.0 - Summary of the Comparative Analysis of
Alternatives. See also the Response to Comment 2.7.1
(Highlight 1) for more information about the components
of a containment remedy.
8.2 Comment: The commentor has been unable to identify a
single closed landfill required to be remedied to meet
MFS. [3]
Response: See Responses for Comments 2.12, 2.12.1 -
2.12.4, 6.1, and 8.1.
8.3 Comment: Commentor stated that the Tulalip Landfill
was evaluated differently than five other CERCLA
landfills (Old City of York, Whidbey Island NAS, OU
2/3, Whidbey Island NAS, OU 4/5, Hamilton Island
Landfill and Everett Landfill). The processes used in
evaluating the other landfills, but not used for the
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Tulalip Landfill, include: (1) screening level
assessments were conducted to screen out chemicals and
media of potential concern; (2) baseline risk
assessments were conducted (except where the screening
assessment identified negligible risk); (3) background
concentrations of all media were evaluated; (4)
screening values were appropriately applied; (5) site
data were appropriately used; and (6) remedial impacts
were completely evaluated. [3]
Response: See Responses to Comments 2.4.1 and 2.14.
8.4 Comment: Commentor suggested that EPA's cleanup
approach at the landfill was not consistent with other
remedy selections at other federal facilities within
Region 10. [1]
Response: EPA cannot respond specifically to the
comment because the Agency is not sure what the
commentor means by "other federal facilities". See
"Responses to Comments 2.4.1 and 2.14 for responses to
other similar comments regarding consistency with other
sites.
8.5 Comment: Commentor asked if EPA or its consultant,
Weston, had reviewed or evaluated the RODs for the
Whidbey Island, Hamilton Island, and Columbia River
landfills prior to issuing the Proposed Plan on August
4, 1995. [2]
Response: CERCLA and the NCP require that EPA base its
remedy selection on the weighing of nine NCP criteria,
not on the evaluation of RODs from other similar sites.
Consequently, EPA did not specifically evaluate each
ROD for the above-mentioned sites before EPA issued the
Proposed Plan for the Tulalip site. Instead, EPA
followed the Presumptive Remedy process for
abbreviating the RI/FS and remedy selection processes.
The basis of the Presumptive Remedy Guidance is an
evaluation of the process and decisions at 30 similar
landfills. EPA's Presumptive Remedy Guidance
identified those alternatives that satisfy the nine NCP
criteria. EPA maintains consistency by following not
only CERCLA and the NCP but also appropriate Agency
guidance and policies.
In preparing for the Responsiveness Summary, EPA has
examined the RODs for the two operable units at Whidbey
Island NAS OUs 2 and 4 and Hamilton Island. (EPA does
not know what the commentor means by "Columbia River
Landfills" and therefore can not respond to that part
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of the comment). EPA has determined that the
investigation and evaluation processes for these sites
differed•from the Tulalip Site because these sites did
not follow the presumptive remedy process. The Whidbey
Island OUs and the Hamilton Island Site were
construction debris landfills, whereas the Tulalip Site
was a commercial/industrial landfill where hazardous
substances were disposed. Construction debris
landfills are not similar in terras of risk concerns to
municipal landfills or commercial/industrial landfills.
Additionally, based on early RI data gathered at the
Hamilton Island Site, it became clear to the Agency
that remedial action at the Site may not be necessary.
However, to fully substantiate a no remedial action
determination for Hamilton Island, EPA conducted a
comprehensive baseline risk assessment. In contrast,
at the Tulalip Site, where RI data indicated the
possible need for remedial action, a streamlined
baseline risk assessment was sufficient to support the
need for remedial action. Also, Tulalip Landfill,
unlike the Whidbey Island OUs and the Hamilton Island
. Site, was sufficiently similar to municipal landfill
sites that utilizing the presumptive remedy process at
Tulalip was appropriate. See Responses to Comments
1.1, 2.1, 2.4.1 and 2.14 for more details.
8.6 Comment: Commentor indicated that remedial activities
at Whidbey Island (EPA assumes the commentor means OUs
2 and 4 as in other comments made by the commentor),
Hamilton Island, and Columbia River did not involve an
impermeable cap. The majority of these landfills used
a "comprehensive baseline risk assessment" rather than
a "screening level risk assessment." Additionally,
frequency of detection and background data were taken
into account in the "baseline risk assessments." [2]
Response: As explained in the Responses to Comments
2.4.1 and 2.14, these sites did not follow the
presumptive remedy process and therefore these sites
are not comparable to Tulalip Landfill, for which EPA
and the Respondents agreed the presumptive remedy
approach was appropriate. Under the presumptive remedy
process which EPA followed for the Tulalip Site, a
streamlined baseline risk assessment is sufficient to
justify an interim remedial action. EPA does not know
• what the commentor means by the "Columbia River" site.
8.7 Comment: Commentor indicated that the Tulalip Landfill
shares few similarities to landfills located at Whidbey
and Hamilton Islands and that drawing comparisons
between these landfills is inappropriate. [2]
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Response: EPA agrees that these sites are not similar
to the Tulalip Landfill and are not good examples to
use in comparing investigation and evaluation
processes. See Response to Comment 2.4.1 and 2.14.
9.0- HYDROGEOLOGICAL ISSUES
9.1 Comment: Commentors asked if lateral or tidally
influenced flow of groundwater is present through on-
site waste and if groundwater flow beneath the site
would continue to be effected by existing wastes at the
site even after surface infiltration of rain water was
eliminated. If so, the commentors asked how the
current recommended action would prevent horizontal
contaminated groundwater flow from influencing Zone 1
and Zone 2 groundwater. [1] [4]
Response: EPA expects that installation of a cap on
the landfill will significantly reduce the downward and
horizontal movement of contaminated groundwater by
reducing rainfall as a source of groundwater recharge.
Groundwater modeling suggests that Alternative 4c is
expected to reduce the average infiltration of rainfall
by more than 99 percent. Rainfall is the primary
source of groundwater in the refuse layer (Zone 1) at
the Tulalip Landfill. Rainfall also provides the
primary driving force for groundwater discharging to
the seeps and recharging to a deeper layer beneath the
refuse (Zone 2). Currently, the water level in the
landfill is generally higher than the water level in
the surrounding sloughs. Groundwater tends to flow
from areas with higher water levels to areas with lower
water levels. Groundwater in Zones 1 and 2 is
currently flowing radially away from the center of the
landfill towards the sloughs. During the summer months
when little rainfall occurs and the water level in the
refuse layer is lower, the number of seeps decreases;
during the winter months when abundant rainfall occurs
and the water level in the refuse layer is higher, a
greater number of seeps are found. Installing a cap on
the landfill is expected to' eliminate the downward and
lateral movement of groundwater through the refuse and
the formation of seeps by cutting off rainfall as the
source of groundwater recharge. As a result, most
waste will no longer be saturated or subject to
infiltration by rainwater.
EPA believes that groundwater in the refuse layer (Zone
1) is not significantly (if at all) impacted by tidal
fluctuations, based on EPA's review of the results of a
72-hour tidal study conducted by the PRPs and described
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in the Remedial Investigation report (HLA, 1995,
Section 3.6). Water levels in Zone 1 monitoring wells
are several feet higher than the high tide levels in
the surrounding sloughs.
A relatively small amount of the refuse is located
within the Zone 2 interval below the landfill (i.e.,
within the former barge canals). Regional groundwater
flow is expected to resume within Zone 2 once the
groundwater mound in Zones 1 and 2, caused by
infiltration of rainfall into the landfill, is reduced
or eliminated by Alternative 4c. EPA expects that the
rate of migration of contaminantfs in Zone 2 to the
sloughs will be significantly reduced due to the lower
groundwater flow velocities anticipated under the
regional groundwater flow gradient and because of the
reduced volume of waste available for leaching.
9.2 '"""" Comment: Commentor asked how much leachate is
presently discharging from the site and how much
leachate was expected to discharge with the
implementation of Alternative 4c. [1]
Response: Leachate currently discharges through
leachate seeps in the perimeter landfill berms onto
wetlands surrounding the Site, and down into the Zone 2
aquifer and then into the sloughs. Construction of the
Alternative 4c landfill cap is expected to reduce the
total leachate discharges from the landfill from
approximately 130 gallons per minute (gpm) to less than
0.4 gpm (Colder, 1995a, Table 3-2); this represents a
reduction of more than 99 percent. Discharges of
leachate through the seeps is expected to be eliminated
in approximately 2 years.
Based on field observations and estimates from the
groundwater modeling developed by the AOC Respondents
and summarized in the RI Report (HLA, 1995, Section
3.4) and the FS Report (Colder Associates, 1995a,
Section 1.2.4), between 6 and 45 gpm currently
discharge from the surface seeps. Discharge is higher
during rainy months and lower during relatively dry
summer months. Leachate seeps represent about 5
percent to 35 percent of the total groundwater
discharge from the refuse layer. According to
groundwater modeling estimates, 65 percent to 95
percent (43 to 82 gpm) of the leachate currently
discharges into the Zone 2 sand layer beneath the
landfill.
Approximately 2 years following construction of the
Alternative 4c cap, any leachate present under the cap
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is expected to move into the underlying Zone 2 layer.
The surface seeps would be eliminated due to the
lowering of the groundwater level within the refuse
layer to an elevation below that of the seep locations.
The amount of leachate discharging to Zone 2 is
expected to drop rapidly for the first couple of years
following construction of the cap and then decrease
more gradually to nearly zero within a decade. For
other alternatives such as the various leachate
interception proposals (e.g., Alternatives 2b and
2b [ii]) the amount of leachate discharging to Zone 2
will drop rapidly over the first year following
construction, but will then fluctuate widely between
less than 1 gpm to 50 gpm due to seasonal variation in
rainfall infiltration (Colder Associates, October
1995b, Figure 4-1). This is based on the assumption
that the leachate interception system will operate at
100% efficiency, which is unlikely. If the leachate
interception system operates at less than 100%
efficiency, due to fouling or plugging, then the
discharge to Zone 2 would increase. The seasonal
variation in leachate discharge predicted for the
leachate interception alternatives results from the
lack of an impermeable cap that would prevent the
generation of leachate during the rainy seasons.
10.0 DATA QUALITY/DATA EVALUATION OF 1988 SITE DATA
10.1 Comment: Commentor expressed the opinion that Tulalip
Landfill EPA Case 895627 data are questionable and
should not be relied upon for quantitative purposes.
Specifically, their findings call into question all
data produced by CompuChem for Case 8956 and reportedly
provide evidence of flaws in data produced by Rocky
Mountain Analytical Laboratories (RMAL).for Case 8956.
Commentor indicated that the contents of several
documents support their argument. These documents
include: correspondence from EPA's Office of Inspector
General and associated memoranda concerning the
Investigation Referral Contract Lab Program; an
internal EPA investigative report of the agency's
Environmental Monitoring Systems Laboratory (EMSL);
telephone logs; data validation checklists and data
assessments; and excerpts from deposition transcripts
from an EPA employee and CompuChem employees. [3]
27 EPA Case 8956 refers to the sample group number for the 1988 surface
soil and water data for the source area of the Tulalip Landfill.
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Commentor suggested that CompuChem's data should be
disqualified due to the laboratory's possible failure
of performance evaluation (PE) samples and its failure
to comply with established EPA procedures. Commentor
asserted that the results of the quarterly blind PE
samples analyzed between October 1987 to May 1988
should be obtained and evaluated. [3]
Further, because the commentor was not provided with
any telephone logs documenting dialogue between EPA,
CompuChem, or RMAL, the commentor suggested that
participating laboratories failed to inform EPA of
problems as they arose (e.g., a broken sample container
and a lost sample). Commentor indicated that this
represents a direct conflict with the 7/87 and 10/86
CLP SOW. [3]
Response: Regarding the reliability of the data from
Case 8956, EPA has re-reviewed the data and made a
determination that the data is reliable for its use in
the Streamlined Risk Assessment. This review can be
found in the Support Document for the Placement of the
Tulalip Landfill on the National Priorities List (EPA,
1995b). In instances where qualified data were used by
EPA, the potential bias associated with the qualified
data relative to human health or ecological based
levels of concern was considered. One such example
would be the use of contaminant data that is above
human health or ecological based levels and has an
associated data qualifier describing its value as being
potentially biased low (meaning that-, the true
concentration of the contaminant may be higher).
Regarding CompuChem's performance in analyzing PE
samples, EPA has reviewed the PE samples that were
relevant to Case 8956 (QB2 and QB3 were analyzed before
and after samples for this Case) and found a very
slight exceedance of the acceptable limit for benzene
in QB2 and a low bias reporting the phenol compounds in
QB3. With these results, in addition to all quality
control data for Case 8956, EPA finds no valid reason
to disqualify CompuChem's data for Case 8956.
Regarding the absence of telephone logs between EPA,
CompuChem or RMAL, concerning a broken sample container
and a lost sample, shipment or discrepancies in the
documentation are resolved with the Sample Management
Office (SMO) and noted in the comments section of the
"Contents for Gray Envelope". The Gray Envelope may
not be found with the sample batches for the Tulalip
Landfill; however, this information is redundant
because the Field Sample Data and Chain-of-Custody form
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and the Organic Sample Traffic Report form would also
record receipt of the samples by the laboratory. (For
further details see Woods, 1996 in the AR for the
interim ROD.)
10.2 Comment: Commentor concluded that one or more flaws
exist with the EPA Case 8956 data. In summary, it is
the opinion of the commentor that the data is
considered flawed and not reliable for quantitative use
because of (i) the high percentage of qualified data;
(ii) the omissions and errors of participating
laboratories and field sampling personnel to comply
with established procedures required by EPA; and (iii)
the inability of EPA to provide the complete file purge
documentation for CompuChem or RMAL which is necessary
to verify that all laboratory procedures were followed.
[3] . .
Response: See Response to Comment 9.1. In addition,
in its review of the documentation, EPA could find no
significant deviations from procedures by participating
laboratories or field contractors that would warrant
rejecting any of the data from Case 8956 that has been
used. For more specific information, see the Support
Document for the placement of the Tulalip Landfill on
the National Priorities List (EPA, 1995b).
Regarding complete file purge documentation, EPA agrees
that two documents may be missing for some of the data.
However, the information'''!^ these documents is
redundant and can be obtained from information in other
documents that are part of the sample data package.
For further details see Woods, 1996 in the AR for the
interim ROD.)
10.3 Comment: Commentor states that many errors were
committed by (i) the EPA's" "contractor (i.e., Ecology &
Environment, Inc.) in sample documentation, (ii) the
EPA in copying the original data, and (iii) the
contract laboratories in reporting data. These errors
are summarized below. [3]
• Chain-of-custody (COG) records for organic data
were broken.
• No COC for copies were observed with signatures
and data and time of sample receipt by laboratory.
• The COC forms for both inorganic and organic
samples did not document if container custody
seals were intact.
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• The sample descriptions from the inorganic
laboratory data indicated that many of the water
samples were collected improperly (i.e., some of
the samples were described as cloudy, thus
suggesting that particulates from the sediment
were introduced into the sample at the time of
collection).
• The complete "case file purge" for both organics
and inorganics was not available. This should
have included (i) the worksheets necessary to
verify the percent moisture content of the organic
sediment sample data; (ii) sample tags and sample
tracking records within the laboratory; and (iii)
documentation describing the condition of sample
bottles upon receipt (e.g., temperature).
Response: With regard to missing Chain-of-Custody
(COC) forms or COC forms without signatures and dates
of receipt by the laboratory and verification of sample
condition, EPA has addressed these deficiencies along
with the available redundant information found in the
signed Traffic Reports from the labs. This information
can be found in the Support Document for the Placement
of the Tulalip Landfill on the National Priorities List
(EPA, 1995b).
Regarding the worksheets for verifying percent moisture
content of the organic sediment data, additional
verification of percent moisture data can be acquired
from the inorganic data packages since both the
inorganic and organic laboratories perform this same
determination on split samples.
Regarding sample tracking records within the
laboratory, EPA has reviewed the previously identified
audit reports for these labs and has found that
sufficient sample tracking procedures were in place at
the time that Case 8956 samples were within these
facilities. (For further details see Woods, 1996 in
the AR for the interim ROD).
Regarding the confirmation of sample temperature upon
receipt, EPA believes that elevated sample temperatures
would have resulted in an overall low bias for some
organic compounds and possibly mercury results. For
sample results that were measured above Human Health or
Ecological based levels of concern, EPA believes the
data to be suitable for its intended use.
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10.4 Comment: Commentor stated that neither the EPA's
Support Document (April 1995) for the placement of the
Tulalip Landfill on the National Priorities List nor
the additional documents provided to the PRPs alleviate
these concerns. [3]
The commentor questioned the reliability of the RMAL
and CompuChem generated data based on the laboratories
(i) non-compliance with the contract laboratory program
statement of work (SOW) . requirements for sample
tracking procedures; (ii) analysis of samples by staff
lacking documented credentials; (iii) RMAL's lack of
standard operating procedures (SOPs); and (iv)
CompuChem's failing scores on the performance
evaluation samples. [3]
Response: Regarding PE scores, see Response to Comment
9.1. EPA has reviewed the commentor's concerns
regarding alleged non-compliance with CLP SOW
requirements for sample tracking, credentials of
laboratory staff and status of RMAL's SOPs. Upon
reviewing audit reports and available documentation,
EPA believes that the commentor's expectations of the
level of detail contained in internal tracking
documents are much higher than what EPA expected or
required of the laboratories under contract. At the
time samples for Case 8956 were within the
laboratories, these facilities met the requirements of
the CLP SOW for internal sample tracking. (For further
details see Woods, 1996 in the AR for the interim ROD).
Regarding the status of RMAL's SOPs, audit reports of
RMAL cite the absence of SOPs. This occurrence makes
reference to an instance where the agency had not
forwarded the SOPs to the contract auditor in time for
the audit. (For further details see Woods, 1996 in the
AR for the interim ROD).
Regarding laboratory staff credentials, EPA
acknowledges that the Routine On-site Audit Reports and
Data Package Audit Reports state that staff resumes
have not been submitted to the Agency (a contract
requirement at the time). However, during the on-site
audits, the auditors did make a determination that the
personnel performing specific job duties met the
required educational and experience requirements,
despite the fact that they did not have the required
resumes on file with the Agency. (For further details
see Woods, 1996 in the AR for the interim ROD).
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11.0 STREAMLINED BASELINE RISK ASSESSMENT FOR INTERIM REMEDIAL
ACTION
General Comments
11.1 Comment: The commentor agrees with the Risk Assessment
findings and believes the assessment is a valid basis
to proceed with the interim remedy. The commentor also
supports the time line for implementing the remedy and
opposes the extension of the public comment period
because it interferes with the timely remediation of
the site. [10]
Response: In response to the extension requests from
PRPs, EPA agreed twice to extensions of the public
comment period from 30 days to a total of 80 days.
This 80-day comment period for the Proposed Plan was 50
days longer than the minimum defined by the NCP. EPA
does not believe the extension will significantly, delay
the construction and operation of the remedy. However,
EPA denied a subsequent request for an additional
extension of the comment period because EPA believes 80
days is sufficient time to comment. Also, the Agency
has not developed responses to comments submitted to
EPA after the close of the comment period for inclusion
in the Responsiveness Summary unless information
submitted with the late comments would significantly
alter the response action at the site.
11.2 Comment: The commentor claims that the Risk Assessment
was manipulated to support a predetermined remedy,
namely 4c, and that The Tulalip Tribes have wanted this
area to be filled for commercial development since the
early 1960s. [8]
Response: The Streamlined Risk Assessment, as
explained in earlier responses (see Responses to
Comments 1.1, 2.1 and 2.7.1), was a streamlined
baseline risk assessment that satisfies all the
pertinent requirements of CERCLA, the NCP, and EPA's
presumptive remedy and risk assessment guidance. The
interim containment remedy selected by EPA for the
Tulalip Landfill source area falls within the scope of
a presumptive remedy. Additionally, when selecting a
remedy, EPA must follow a prescribed procedure that
involves an evaluation of the alternatives under
consideration against evaluation criteria set forth in
the NCP. EPA has completed this process of evaluation
and has determined that Alternative 4c is the most
appropriate remedy for the Site. It was only after the
completion of the Streamlined Risk Assessment and the
evaluation of the alternatives that EPA determined
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Alternative 4c to be appropriate. The rationale for
selecting Alternative 4c is documented for public
comment in the Proposed Plan and interim ROD. Based on
this evaluation, EPA concluded that the Alternative 4c
provides the best balance of trade-offs among the
alternatives with respect to the nine NCP criteria that
EPA uses to evaluate alternatives.
EPA cannot comment on what The Tribes' plans were for
the Site in the early 1960s.
11.3 Comment: A cleanup decision can not be made at this
time because the Risk Assessment is flawed. [6]
Response: EPA does not agree that the Streamlined Risk
Assessment is "flawed". The Streamlined Risk
Assessment was developed in accordance with CERCLA, the
NCP, and EPA guidance. It is sufficient to support EPA
decisionmaking with regard to.an interim response
action at the Site, and contains no deficiencies that
would prohibit it from being used for this purpose. If
the commentor is stating that the Streamlined Risk
Assessment should be a comprehensive baseline risk
assessment, then the commentor should see the Responses
to Comments 2.1, 2.1.1, 2.1.2, 2.2, 2.3.1 and 2.3.2.
For information about the 1988 data quality, see
Responses to Comments 2.9.2, 2.9.3 and 2.9.4.
11.4 Comment: Commentor asked if the risks in the
"screening risk assessment" are accurate and real. [2]
Response: The Streamlined Risk Assessment provides a
comparison of site data to "comparison numbers"
considered to be protective of human health and
environmental, resources, which include chemical
concentration standards, criteria, and risk-based
concentrations. Based on the results of the RI and the
Streamlined Risk Assessment, which show exceedances of
. the comparison numbers in on-source and off-source
media, EPA has concluded that an interim remedial
action is necessary to address these risks. According
to CERCLA, the NCP, and EPA guidance on presumptive
remedies, the information and analyses provided in the
Streamlined Risk Assessment are sufficient for
decisionmaking purposes regarding an interim remedial
action. Appendices A and B of the Streamlined Risk
Assessment provide additional information on how some
of the comparison numbers were developed, and why
exposure to chemical concentrations that exceed the
comparison numbers is expected to lead to adverse
effects. For a discussion of the target risk levels
used by EPA from the Region III risk-based calculations
-------
and the MTCA Tables, see Responses to Comments 11.9,
11.10, 11.17, 11.31 (last bullet), 11.32, 11.33 and
11.38.
11.5 Comment: Commentor stated that a discussion of the
various options for future development of the site
should be included in the Risk Assessment because most
readers will not have access to the land use document
referenced in the report. [3]
Response: While a detailed discussion for future land
uses was not included in the Streamlined Risk
Assessment, conservative exposure assumptions were
incorporated in the Streamlined Risk Assessment to
ensure that exposures associated with any possible
future uses would be evaluated and considered during
remedy selection. Historically, EPA has been
criticized for selecting remedies that have, in effect,
"placed a fence around a site" and prohibited any
future productive use of the site. Accordingly,
relatively recent EPA guidance indicates that EPA
should consider future land use during the remedy
decision process as EPA has done at the Tulalip
Landfill (EPA, 1995c).
The information requested by the commentor is contained
in the Big Flats Land Use Program (Tulalip Tribes,
1994) document, referenced in the Streamlined Risk
Assessment. This document is part of the
Administrative Record for this project and is therefore
accessible to the public. In summary, this document
states that the Tulalip Landfill on-source area has
been placed in an "industrial" use category. Any
future "industrial" or "commercial" use of the landfill
surface should be limited to ensure the continued
integrity of the containment system. The wetlands
areas adjacent to the landfill have been placed in a
"conservation" use category. According to the
description of "Conservation" use, no development may
occur in these areas with the exception of utility
crossings.
It should be noted that a landfill cover is not an
ideal surface for future development. While a landfill
cover would allow some limited use or development on
the landfill surface,' significant restrictions are
necessary to prevent damage to the cover system are
included in the selected remedy. When design and
construction are complete, EPA and The Tulalip Tribes
will develop a document titled "Routine Use of Tulalip
('Big Flats') Landfill" that delineate which routine
site uses may occur and which routine site uses shall
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not occur on the surface of the cover. Any commercial
or development activity on the surface will require a
written agreement between EPA and the Tribes to ensure
the continued integrity of the cover.
As a point of clarification, the term "industrial" as
defined by the Tulalip Tribes is different from the
State of Washington MTCA definition of "industrial."
See Responses to Comments 11.10, 11.37 and 11.38.
11.6 Comment: The commentor stated that extensive valuable
ecological and chemical data collected during the
remedial investigation were not, but should have been,
used in the Risk Assessment28 Specifically, the
commentor requested a reason why the following data
were not used: [3] [8] [17] [18]
• Studies of the degree to which landfill chemicals
accumulated in shellfish and small mammals.
Response: Due to problems with the quality of some of
the RI analytical data developed by the AOC
Respondents, EPA required certain parts of the RI to be
repeated, including sampling and analysis of shellfish
and small .mammals. Therefore, these data were .not
available for the Streamlined Risk Assessment.
However, these data are not necessary to select an
appropriate interim containment remedy for the Site.
The Streamlined Risk Assessment is a complete document
that contains sufficient information to proceed with
selection of an interim remedy for the source area.
These data are appropriately included and will be
evaluated in the comprehensive baseline risk
assessment, which will assess potential risks to the
off-source wetland resources surrounding the landfill.
Accordingly, the data will be available and used in the
comprehensive baseline risk assessment and remedy
selection evaluation for the off-source area.
• Studies of the toxicity of sediments adjacent to
the landfill to clams and amphipods.
Response: Due to problems with the quality of the
analytical data, the AOC Respondents had to repeat the
M\ The commentor contradicts another comment he has made. See Comment
11.14, where the same commentor states that he is of the opinion that the off-
source area should only be evaluated in a detailed risk assessment proposed as
part of a non-presumptive remedy. All of the media that the commentor asserts
in this (11.6) comment should have been included in the Streamlined Risk
Assessment (shellfish, small mammals, etc.) are off-source data.
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c^am investigation; therefore, the toxicity studies
could not be included in the Streamlined Risk
Assessment. The amphipod test results were not be used
in the Streamlined Risk Assessment because the purpose
of the Streamlined Risk Assessment was to directly
compare analytical chemistry results to available
comparison numbers. Because the results of the
bioassay will require a statistical evaluation and
interpretation, these data will be evaluated in the
comprehensive baseline risk assessment and remedy
selection evaluation for the off-source area.
• Data on chemical residues in sediments, soils,
surface waters and tissues of sculpin residing in
surface water adjacent to the landfill.
Response: The commentor's assertion that these
data were not used in the Streamlined Risk
Assessment is incorrect. Detected chemical
concentrations in sediments, soils, surface water,
and sculpin were incorporated into the Streamlined
Risk Assessment and evaluated. Section 2 of the
Streamlined Risk Assessment summarizes the
analytical data used in the Streamlined Risk
Assessment (including sediments, soils, surface
water, and sculpin tissues), and Table 2-1 in
Section 2 lists the chemicals detected in on-
source (surface water, leachate seep SP01, surface
soil, Zone 1 and Zone 2 groundwater) and off-
source (surface and subsurface soil, surface and
subsurface sediment, surface water, leachate seeps
SP02-SP11, fish tissue) media. Numerous
chemicals were found in sediments, soils, surface
waters, and/or fish tissues at levels that exceed
comparison numbers considered to be protective of
human health and the environment, including
polycyclic aromatic hydrocarbons (PAHs),
PCBs/pesticides, and inorganics.
The presumptive remedy guidance specifies that the
Agency does not need to evaluate all exposure pathways
in a streamlined baseline risk assessment. See
Response to Comment 11.16.
11.7 Comment: The commentor felt that the 1988 surface
water data incorporated into the Risk Assessment should
not have been used because on-site activities at the
time of collection may have caused non-representative
contamination of this medium. Also, the commentor
stated that the analytical techniques used in the 1988
investigation are unreliable, and five samples are not
sufficient to characterize the 143-acre site. [3]
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Response: The 1988 sampling design took the
possibility of cross contamination into account by
placing sampling locations away from any on-site
activities. As summarized in section 11 of the 1988
E&E report, a site inspection was conducted prior to
sampling to document on-site activities and to
determine sampling locations that would not be affected
by on-site activities. Consequently, EPA has no reason
to believe that cross contamination of the landfill
surface/pooled water is a result of contamination of
the construction debris disposed on-site in 1988.
EPA believes that the 1988 data is reliable (see
Response to Comments 2.9.2 and 2.9.3.). However, EPA
notes that the 1998 data may be relatively less useful
for purposes of making decisions with regard to an
interim action at the Site than data collected during
the RI because it is older. Clearly, the 1988 data
represent 1988 Site conditions, which is useful
information;, however, the data may not represent
current Site conditions. The 1988 data was used in
conjunction with the data collected for the RI to
evaluate on- and off-source exceedances in the
Streamlined Risk Assessment. The 1988 data included
surface soil and surface water from the landfill
surface. The 1995 RI data from leachate seep SP01 was
used to determine the condition of leachate coming from
the landfill surface. EPA notes that the RI data from
seep SP01 exceeded comparison numbers for some
chemicals, including phenanthrene, dissolved iron,
dissolved lead, total cyanide, total iron, total lead,
heptachor, Aroclor 1016, and ammonia (see interim ROD
Table 6-4).
Regarding the comment that "five samples are not
sufficient to characterize the 143-acre site," EPA
agrees that the five samples are insufficient to fully
characterize the entire 143-acre landfill surface.
However, it would be inappropriate to conclude that
just because the 5 samples do not fully characterize
the landfill surface, that the data is therefore
totally useless and should be completely ignored. The
Streamlined Risk Assessment included these 5 samples
and measured the results against "comparison numbers"--
- chemical concentration levels that are considered
protective of human health and the environment. The
Streamlined Risk Assessment indicates that in 1988, at
5 sample locations on the landfill surface,
concentrations of some chemicals in surface water
exceeded levels that are considered protective of human
health and the environment. EPA believes it is more
appropriate to consider such information, while keeping
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in mind the potential limitations of its usefulness,
than to ignore it. See Response to Comments 2.9.2 and
2.9.3.
11.8 Comment: Commentor asked if the EPA used ecological
data as well as background data in the Risk Assessment.
[1]
Response: Not all of the ecological data collected
during the remedial investigation were available at the
time the Streamlined Risk Assessment was prepared. See
Response to Comment 11.6. Some of the data (mammal
tissue, clam tissue) submitted by the AOC Respondents
were of poor quality and could not be used at the time
the Streamlined Risk Assessment was being developed.
The reasons some of the data could not be used include
inappropriately high detection limits for the tissue
data and the loss of tissue samples in the laboratory
for the clam bioassay due to inappropriate,sample
preparation. Analytical data available for fish tissue
was incorporated into Section 2 of the Streamlined Risk
Assessment. In this section, trends in chemical
detections across media were analyzed (Streamlined Risk
Assessment, Table 2-1). See Responses to Comments
11.111 - 11.115.
11.9 Comment: Commentor stated that the screening values
used in the human health evaluation are not enforceable
and do not constitute "criteria." [3]
Response: EPA disagrees with this comment. The
commentor appears to be implying that EPA can only use
promulgated standards when evaluating human health
risks at a Superfund site. Neither CERCLA nor the'NCP
require the use of promulgated or enforceable .standards
in determining acceptable levels of risk at CERCLA
sites. EPA has appropriately used existing state and
federal standards to identify levels which, if
exceeded, indicate a human health or environmental risk
at the Tulalip Site. In the absence of enforceable
standards or criteria, EPA appropriately uses existing
risk-based chemical concentrations which provide a
basis for determining levels of risk to human health or
the environment at a given site. The EPA guidance
document "Streamlining the RI/FS for CERCLA Municipal
Landfill Sites" (EPA, 1990a) states on Page 3 that the
scope of the baseline risk assessment can be
streamlined or limited by "identifying all pathways
that are an obvious threat to human health or the
environment... by comparing RI-derived contaminant
concentration levels to standards that are potential
chemical-specific ARARs for the action... When
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potential ARARs do not exist for a specific
contaminant, risk-based concentrations should be used."
[emphasis-added]. Consequently, Region 10 used the
Region 3 risk-based concentrations because Region 10
considered the exposure assumptions and target risk
levels used in the Region 3 risk-based concentrations
to be appropriate for the Tulalip Site. See Response
to Comment 11.10.
In total, EPA has recorded numerous exceedances of
comparison numbers that are considered to be protective
of human health and the environment at the Site. Site
investigation efforts, including sampling done recently
by certain PRPs as .part of the RI, indicate that
landfill leachate leaving the Site exceeds comparison
numbers for pesticides such as DDT and aldrin,
polychlorinated biphenyls (PCBs), and heavy metals and
other contaminants including chromium, copper, lead,
mercury, nickel, zinc, ammonia, and heptachlor. The RI
documents the presence of hazardous substances
.contaminating soils, sediments, surface water, and
groundwater at the Site. Hazardous substances found in
surface soils at the Sit.e exceeded comparison numbers
in one or more samples at eig"ht of the nine leachate
soil grid locations. At six of the leachate soil grid
locations, subsurface soil samples were collected.
Hazardous substances found in these subsurface soils
exceeded comparison numbers in five of the six
subsurface soil samples. Hazardous substances found in
leachate exceeded comparison numbers at least once in
most of the eleven seeps that were tested. Chemicals
detected in Zbne~ 1 groundwater (located within the
refuse layer of the landfill) exceeding comparison
numbers consisted of the metals copper, lead, nickel,
and zinc, as well as ammonia, cyanide, and the
pesticide heptachlor epoxide. The studies found that
Zone 2 groundwater (located below the refuse layer) was
contaminated at levels exceeding comparison numbers for
the metals copper, lead, and nickel, as well as cyanide
and ammonia. Thus, it is clear that there are
exceedances of chemical-specific criteria to all media
evaluated during the RI/FS at the Tulalip Landfill Site
which warrant the taking of the interim remedial action
specified in the interim action ROD in order to protect
human health and the environment. See Response to
Comment 2.5.5.
11.10 Comment: Commentor asserted that the "screening level"
Risk Assessment misapplied both the EPA Region III
risk-based concentration (RBC) and the cleanup levels
defined by the State of Washington's Model Toxics
Control Act (MTCA). Commentor argued that the EPA
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Region III RBCs, as defined by the EPA, are not
intended to be used as cleanup goals or no-action
levels at CERCLA or RCRA sites. Commentor indicated
that EPA has applied MTCA cleanup standards at other
hazardous waste sites in Washington state where EPA was
involved. [3]
Response: EPA disagrees that human health criteria
were used inappropriately. The risk-based
concentrations used were not indicated to be the
appropriate cleanup levels, they were used in the
Streamlined Risk Assessment to assess risk. Risk
assessment is a distinctly different process than the
process to establish cleanup numbers. EPA uses risk-
based concentrations when established standards or
criteria are not available. MTCA soil cleanup
standards for "commercial/industrial" sites, calculated
under WAC 173-340-740 were also used for comparison in
the Streamlined Risk Assessment. See Responses to
Comments 2.5.4, 11.9, 11.37 and 11.38.
11.11 Comment: The commentor suggested that the document's
title, "Draft Final Risk Assessment for the Tulalip
Landfill Interim Containment Remedy," incorrectly
states that it provides justification for an "Interim
Containment Remedy." The commentor suggested that the
document is in reality being prepared as part of the
Source Area Containment studies and any references to
an interim containment study should be removed.
Commentor also indicated that the document, as .
currently presented, is not a complete risk assessment,
and that any further versions of the document should be
prepared in accordance with the four steps of risk
assessment as defined by the NCP before being
identified as a risk assessment. [3]
Response: The title of the final document was changed
to Tulalip Landfill Risk Assessment for Interim
Remedial Action to address the commentor's concern.
EPA disagrees with the commentor's assertion that the
Streamlined Risk Assessment is an "incomplete"
assessment, see the Responses to Comments 2.1, 2.1.1,
2.1.2.,2.2, 2.3, 2.3.1 and 2.3 . 2. The Streamlined
Risk Assessment has, in fact, been prepared in
accordance with all four components (albeit
streamlined) of a more detailed risk assessment. These
components are: (1) hazard identification and dose
(stressor), (2) response assessment (combined in an
ecological effects assessment component), (3) exposure
assessment, and (4) risk characterization. In the
Streamlined Risk Assessment, the hazard identification
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and dose step of a risk assessment was met by
identifying the chemicals which were detected in on-
site media and by listing the ranges of the detected
concentrations. The response assessment step consisted
of identifying toxicity information (in terms of risk-
based concentrations and criteria) to compare to the
detected chemical concentrations. In the exposure
assessment step, ecological receptors (e.g., marine
organisms) and human receptors (e.g., future site
workers) were identified to support the selection of
appropriate toxicity information (selected in the
response assessment step). Finally, the risk
characterization was conducted by comparing the range
of detected chemical concentrations (identified in the
hazard identification step) to the appropriate toxicity
information (gathered from completing the response
assessment and exposure assessment steps). Risk
characterization results were discussed in terms of
frequency and magnitude of exceedance of risk-based
concentrations and criteria.
11.12 Comment: Commentor asserted that the use of the term
"interim remedy" was incorrectly used throughout the
Risk Assessment. Commentor suggested that an interim
remedy is applied only to reduce imminent threats to
human and environmental health, a condition considered
by the. PRPs as not present at the site. In addition, a
citation to page 1-1, 1st paragraph was requested. [3]
Response: The commentor is incorrect in stating that
EPA may only utilize an interim remedy in circumstances
presenting an imminent and substantial danger. Section
104(a)(1) of CERCLA authorizes a response action
whenever "(A) any hazardous substance is released or
there is a substantial threat of such release into the
environment, or (B) there is a release or substantial
threat of release into the environment of any pollutant
or contaminant which may present an imminent and
substantial danger to the public health or welfare[.]"
(emphasis added). See 42 U.S.C. § 9604(a)(1). In this
case, the release of many different hazardous
substances into the environment has been documented in
the RI/FS that is in the administrative record. For
example, data in the RI/FS shows that there are
numerous exceedances of comparison numbers considered
protective of human health and the environment,
including specific health-based and ecological
standards, criteria, and risk-based concentrations.
Because there are documented releases of hazardous
substances on the Site, EPA may undertake a response
action at the Site regardless of whether those releases
pose an imminent and substantial danger to the public
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health or welfare. However, EPA has determined these
releases of hazardous substances also do pose a
potential imminent and substantial endangerment to
human health and the environment. See Section 6.3 of
the interim ROD, which states that " [c]omparison of the
measured chemical concentrations to the human health
risk-based and ecological effects-based criteria
established under other environmental programs reveals
potential risks to humans and the environment. Based
on the RI/FS and findings in the Streamlined Risk
Assessment, EPA finds that actual or threatened
releases of hazardous substances from the Site, if not
addressed by the selected alternative or one of the
other active measures considered, may present an
imminent and substantial endangerment to public health,
welfare, or the environment."
Congress, in Section 121 of CERCLA, specifically
contemplated early or interim actions, by allowing EPA
to waive ARARs in such cases. In addition, the NCP
preamble states that:
EPA encourages the implementation of interim
action operable units, as appropriate, to prevent
exposure or control risks posed by a site." See
55 Fed. Reg. 8705.
Thus EPA clearly has the ability under CERCLA and the
NCP to address risks posed by a site by using early or .
interim actions, even where those risks do not pose an
" imminent" threat. "~~~
11.13 Comment: Commentor stated that EPA's Tulalip Landfill
"screening risk assessment" was not conducted according
to EPA guidance and can only be used to determine which
pathways are not of concern, not to establish the need
for remediation. Also, the commentor stated that the
Risk Assessment used default exposure assumptions. [3]
Response: The Streamlined Risk Assessment was
developed fully in accordance with EPA's guidance on
risk assessment for presumptive remedies (EPA, 1990a
and EPA, 1993a). Streamlined risk assessments are
appropriate for many sites where presumptive remedies
have been conducted by EPA, such as landfills. These
risk assessments can be used to determine whether early
remedial action is warranted to limit or eliminate
releases from source areas. A comprehensive baseline
risk assessment would typically be conducted thereafter
to address off-source areas of such sites. EPA
believes that it is appropriate to use default exposure
assumptions for streamlined risk assessments unless
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site-specific deviations from such values are readily
available. See Responses to Comments 11/9 and 11.11.
. The commentor did not provide a reference to the
guidance he claims EPA has followed; therefore, EPA
cannot specifically address his concern. For more
discussion about the appropriateness of using a
streamlined risk assessment for the Tulalip Site see
the Responses for Comments 2.1.2, 2.2, 2.3.1, and
2.5.4.
11.14 Comment: The commentor suggested that the document did
not adhere to the scope of the investigation as defined
in the presumptive remedy guidance. Commentor
suggested that receptors and pathways evaluated as part
of the presumptive remedy inappropriately included off-
site receptors and addressed exposure pathways outside
the source area. It is the opinion of the commentor
that the off-source areas should only be evaluated in a
detailed risk assessment prepared as part of a non-
presumptive remedy.29 [3]
Response: Because the leachate from the landfill exits
from the berm into the off-source areas, an off-source
evaluation is appropriately included in the Streamlined
Risk Assessment to qualitatively determine to what
extent the chemicals in the leachate have impacted the
surrounding water bodies and wetland areas. The
presumptive remedy of containing the landfill waste is
designed to prevent chemicals in the source area from
migrating to off-source areas. Therefore, it is very
appropriate to evaluate the off-source areas in light
of potential remedies for the source area. The •
Streamlined Risk Assessment was conducted to document
potential adverse effects associated with the landfill
(e.g., leachate). Therefore, it is appropriate, and
consistent with EPA's presumptive remedy guidance, to
evaluate off-source receptors-, in addition to on-source
receptors, that may be affected by contaminants from
the landfill. See Response to Comment 11.95.
11.15 Comment: Commentor suggested that the Risk Assessment
was not prepared in accordance with the Presumptive
29 EPA notes that the commentor's opinion in this comment that the off-
source areas should not have been evaluated in the Streamlined Risk Assessment
is in conflict with this same commentor's assertions in Comment 11.6 in which
the commentor asserts that some off-source data (mammal tissue, clam tissue,
etc.) that was unavailable for inclusion in the Streamlined Risk Assessment
should have been included in the Streamlined Risk Assessment.
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Remedy Guidance (U.S. EPA 1993) and the specific
purpose of the document is not clearly stated.
Further, -the commentor indicated that no regulatory
background information is provided in the text to
provide the reader an understanding of the context
within which the evaluation was conducted. Commentor
requested that the EPA guidance referred to in the 1st
paragraph of the Executive Summary under the discussion
of "available criteria" be cited (including pages).
[3]
Response: EPA prepared the Streamlined Risk Assessment
fully in accordance with EPA's Presumptive Remedy for
CERCLA Municipal Landfill Sites guidance . (EPA, 1993a)
and other EPA presumptive remedy guidance EPA, 1998,
1991, 1995a, and 1995c). See Responses to Comments
Sections 2.1, 2.2, and 2.3. The regulatory background
information the commentor has requested is presented in
the Introduction (Section 1) of the Final Tulalip
Landfill Risk Assessment for Interim Remedial Action.
Specifically, the purpose of the Streamlined Risk
Assessment is to identify potential exposure pathways
and compare relevant site data to'existing comparison
numbers. The citations.for the comparison numbers are
contained in Sections 3 (pages 3-1, 3-2, 3-3) and 4
(pages 4-2, 4-3) of the Streamlined Risk Assessment.
11.16 Comment: Commentor does not agree that "EPA guidance
for the presumptive remedy risk assessment states that
it is not necessary to calculate multi-chemical, multi-
pathway risks to initiate the remedial action." [3]
Response: EPA disagrees with the commentor. The
presumptive remedy guidances (EPA, 1990a and EPA,
1993a) clearly provides for the initiation of remedial
action without the calculation of multi-chemical,
multi-pathway risks having been performed. See the
Responses to Comments 2.1, 2.2, and 2.3 for EPA's
explanation regarding the appropriate use of a
streamlined baseline risk assessment for selecting a
interim remedy at a Site where a presumptive remedy
approach is appropriate.
11.17 Comment: Commentor does not agree that an exceedance
of regulatory criteria by one sample would trigger
remedial action at any site. [3]
Response: The "Presumptive Remedy for CERCLA
Municipal Landfills" (EPA, 1993), clearly states that
"where established standards for one or more
contaminants In a given medium are clearly exceeded,
remedial action generally is warranted." See the
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Responses to Comments 2.1.2 and 2.5.2 for a more
detailed response. Also, EPA notes that the Agency has
concluded'in the interim ROD that early, interim action
to contain the landfill waste is appropriate at the
Tulalip Site based not on one exceedance of a
comparison number, but on the exceedance of 1367
comparison numbers in many.different media. See
Response to Comment 2.2 -- the table with the number of
exceedances.
11.18 Comment: Commentor stated that very few of the general
and specific comments supplied by Parametrix on the
"Draft Final Tulalip Landfill Risk Assessment for
Interim Containment Remedy" were addressed in the
"Final Tulalip Landfill Risk Assessment for Interim
Containment Remedy." [3]
Response: All of the Respondents' comments on the
Draft Final Tulaldp Landfill Risk Assessment for An
Interim Containment Remedy have been addressed by EPA,
either through revisions to the Streamlined Risk
Assessment or in the Responsiveness Summary. In EPA's
letter of August 4, 1995 (Winiecki, 1995c) (of which
the commentor was carbon copied), the Agency stated
that it considered all comments submitted by Parametrix
and when EPA issued the final Streamlined Risk
Assessment. Additionally, EPA stated that it intended
to provide written responses to outstanding comments
(comments not addressed in the Final Streamlined Risk
Assessment) in the Responsiveness Summary for the ROD.
Those outstanding comments have been added to this
document. See Response to Comment 2.5.1.
11.19 Comment: Commentor asserted that it is inappropriate
at this time to state that remedial action is warranted
at the site because of the number of the errors and
deficiencies in the Draft Final Risk Assessment.
Further, the commentor stated that the purpose of a
"screening level risk assessment" is to identify
chemicals of, potential concern and eliminate pathways
and chemicals of negligible risk. [3]
Response: All significant errors and deficiencies were
addressed before the final Streamlined Risk Assessment
was produced. See Response to Comment 2.5.1 and 11.18.
According to EPA guidance, including "Presumptive
Remedy for CERCLA Municipal Landfill Sites" (EPA,
1993a)/ and "Streamlining the RI/FS for CERCLA
Municipal Landfill Sites" (EPA, 1990a), the Final
Tulalip Landfill Risk Assessment for Interim Remedial
Action, dated August 1995, is a streamlined baseline
risk assessment that is appropriately used to identify
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the need for interim remedial actions. See Response to
Comment 11.13.
11.20 Comment: Commentor stated that several figures in
Section 2 of the Risk Assessment were mis-titled
(Figures 2-2 through 2-6). [3]
Response: EPA can not identify any errors in the
titles of the figures to which the commentor refers.
All figures are properly numbered and titled in the
Streamlined Risk Assessment.
11.21 Comment: Commentor noted tha£g*pages 2-8, 3-3, and 3-4
were not contained in the draft Risk Assessment. [3]
Response: All pages are contained in the final
Streamlined Risk Assessment. Pages 2-8 and 3-4 in the
draft Streamlined Risk Assessment are intentionally
blank.
11.22 Comment: Commentor stated that the word "in" should b"e
"for" on page 2-1, 5th paragraph, in the last complete
sentence on the page. [3] .
Response: EPA has noted the commentor's grammatical
edit.
Human Health Risk Assessment Comments
11.23 Comment: Commentor stated that surface and subsurface
soil should not have been evaluated because future
excavation of the landfill is unlikely. [3]
Response: As a point of clarification, subsurface soil
data from the landfill source area was not available
and therefore not used in the Streamlined Risk
Assessment. Only surface soil data for the source area
from the 1988 data set was available for use the in the
Streamlined Risk.Assessment. The presumptive remedy
guidance (EPA, 1993a), states on page 5,
"(s)treamlining the risk assessment of the source area
eliminates the need for sampling and analysis to
support the calculation of- current or potential future
risks associated with direct contact.". The Agency has
found in the its experience that surface and subsurface
soil data play a small role in the data used to select
a remedy. Therefore, for the Tulalip Site, the Agency
did not focus on gathering subsurface soil data or
additional surface soil data (beyond the 1988 data
gathering effort.)
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EPA agrees with the commentor that "future excavation
of the landfill is unlikely." Institutional controls
such as land use restrictions designed to protect the
integrity of the landfill cover could prohibit
excavation. However, exposure to subsurface soil and
sediment in the off-source areas is possible under the
future use exposure scenarios that have been identified
for the Site. Although the off-source area has been
placed in the "Conservation" use category by the
Tulalip Tribes in "Big Flats Land Use Program" (Tulalip
Tribes, 1994)30, subsurface soil and sediment may be
contacted in this area if there is need to place
utility lines to support on-source development. This
is a likely scenario because restrictions made on
penetrating the cap could necessitate locating utility
lines in the off-source area. Also, people working at
a future industrial/commercial on-source facility may
elect to use the off-source area for recreational
purposes such as fishing, hiking and kayaking on .a
frequent basis. Therefore it must be considered
possible that a person could contact off-source
subsurface soil and sediment. For information about
the "Conservation" category see the Response to Comment
11.5.
11.24 Comment: Commentor stated that fish consumption is not
a complete exposure pathway in the off-source area
because Tribal fishermen will not harvest the tideflat
species present there. [3]
Response: Fish consumption is a complete exposure
pathway. Txibal members consume bottom fish (i.e.,
resident, sediment-dwelling fish) caught in the
vicinity of the Site.31
11.25 Comment: Commentor stated that use of a 1CT6 cancer
risk level is inappropriate for children because they
are exposed for a subchronic duration of time, not the
chronic exposure assumed in recommending an acceptable
risk level of 1CT6. [3]
Response: The use of a 10"6 cancer risk level is
appropriate for children because, due to their small
body size and greater potential for exposure (e.g.,
their higher ingestion rate of soil), they are
30 Note that the Tribes designation system for land use is different from
the designation system specified in MTCA.
31 Personal communication, Eric Winiecki, EPA Remedial Project Manager,
with Tom McKinsey, Tulalip Superfund Coordinator, January 19, 1996.
D-131
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considered a sensitive population which is typically
protected by using a 10~6 cancer risk level for a
target risk. It does not matter whether a child's
exposure is chronic or subchronic because cancer risk
is considered cumulative over a lifetime, i.e., a 10"6
cancer risk level would be considered appropriate
whether the exposures occurred over a few months or
many years.
11.26 Comment: Commentor stated that chemicals with a low
frequency of detection should have been dropped from
the evaluation. [3]
Response: The purpose of the Streamlined Risk
Assessment was to identify the magnitude and location
of exceedances of comparison numbers including risk-
based concentrations and ambient water quality criteria
for hazardous substances released from the landfill.
Considering the heterogeneous nature of a landfill (and
the associated leachate leaving it) , the
appropriateness of eliminating a contaminant based on
frequency of detection is questionable. The magnitude
of the detection must also be considered in the risk
assessment approach. If a contamina'nt is detected
infrequently but has a very high concentration, an
exposure risk still exists. Eliminating a contaminant,
in most cases, based on frequency of detection is not
advocated by EPA guidance.
11.27 Comment: Commentor stated that it is both incorrect
and inconsistent with EPA's own Presumptive Remedy
Guidance to apply a future industrial/commercial use
scenario (with children at a day care facility) to the
Tulalip site and then use this scenario to identify
risks which must be mitigated off-source. Commentor
goes on to state that the future use specified
(industrial/commercial) is not considered appropriate
for the Tulalip Landfill site because former landfill
sites are not expected- to support such uses. [3]
Response: The Tulalip Site includes both on-source and
off-source areas. In light of the proposed future land
uses identified in the Big Flats Land Use Program
(Tulalip Tribes, 1994), exposure of children and adults
to both on-source and off-source areas is a reasonable
scenario. See the Response to Comment 11.5 for a more
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detailed description of the proposed future land uses
for the site. Evaluation of potential off-source
health risks is appropriate and consistent with the
Presumptive Remedy Guidance. See Responses to Comments
11.14 and 11.95.
EPA guidance specifies that the Agency consider
potential future uses of a cleanup site before a remedy
is selected to ensure that the selected remedy will not
preclude potential uses that are important to the local
community (Future Use of Superfund Sites, EPA, 1995c).
See Response to Comment 2,7.2. EPA developed this
policy regarding future use because in the past, some
of the cleanup decisions the Agency made at certain
sites were criticized for preventing or inhibiting
productive future use of the sites. EPA has
accordingly considered future uses in its approach to
the Tulalip Site.
Landfills remediated with covers have been developed
for productive uses (e.g., parks) other than as a
landfill after the landfill has been closed and
covered. EPA believes that more landfill closures
should be designed to accommodate future use of the
landfill surface. Reuse of previously contaminated
property in a manner that is protective of human health
and the environment is beneficial to the community and
goes hand-in-hand with EPA's national "Brownfield"
initiatives. Remediating a site that is not compatible
with some type of future productive use (e.g.,
recreational use) is a loss to the community and
society as a whole. Reuse of remediated property
lessens the pressure on communities to develop
undeveloped property.
The selected remedy includes institutional controls.
These would include controls on use of the Site, such
as land use restrictions that limit or prohibit
development or activities conducted on the Site so as
to not interfere with performance of the selected
remedy, and to prohibit activities that are not
protective of human health and the environment. When
design and construction of the interim remedy are
complete, EPA and the Tulalip Tribes shall develop and
approve a document entitled "Routine Use of Tulalip
('Big Flats') Landfill," the purpose of which shall be
to ensure the continued integrity of the cover system.
This document shall delineate routine site uses that
may occur on the surface of the cover and uses that
shall not occur, in accordance with the land use
restrictions established in the interim ROD. This
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document shall be implemented at the Site in
perpetuity, or until EPA and The Tulalip Tribes
determine in writing that implementation of the
document is no longer necessary at the Site. After the
document is approved by EPA and The Tulalip Tribes, the
document can only be modified by mutual written
agreement by both EPA and The Tulalip Tribes.
Any commercial or development activity on the landfill
surface will require advance, written agreement between
EPA and the Tribes to ensure the continued integrity of
the cover system and to ensure protection of human
health and the environment.
A clearly visible sign shall be placed and maintained
into perpetuity at the landfill entrance which
summarizes the activities that may occur on the
landfill cover, and shall also summarize the
restrictions on use, as described in the "Routine Use
of Tulalip ('Big Flats') Landfill" document. The sign
shall include the phone number of a Tribal officer or
employee who is familiar with the requirements of the
"Routine Use of Tulalip ('Big Flats') Landfill document
and is able to provide direction to potential users of
the Site regarding the document.
11.28 Comment: Commentor noted that potential health risks
from chemicals in sediments were estimated by assuming
that a child at a day care facility built on-site would
be exposed to the sediments 250 days/year. Commentor
stated that this is almost certainly an overestimate of
potential exposures because the sediments are tidally
inundated and would require extensive stabilization and
placement of fill material prior to construction of any
buildings. [3]
Response: In the Streamlined Risk Assessment, EPA used
reasonable, available risk-based concentrations (i.e.,
those calculated by EPA Region III and presented in
MTCA) to address exposure a child may have at the Site,
in this case a commercial exposure. It is assumed that
if a commercial facility frequented by children were
developed on the landfill surface, a child could
reasonably wander into this area during the day while
playing, receiving exposure during the estimated 250
days/year. In addition, 250 days/year is a possible
exposure frequency for a child recreational user if,
for example, ballfields or other recreational
facilities were placed on the landfill surface (there
are no available exposure default criteria which
address a recreational scenario). See Response to
Comment 11.25.
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11.29 Comment: Commentor states that it is inappropriate to
compare off-source surface and subsurface sediment data
to soil screening values for an industrial site because
off-source biological resources are not directly
exposed to on-source soils and sediments. [3]
Response: Future commercial/light industrial
development of the on-source area could facilitate
chronic exposure of off-source receptors to on-source
contamination. For this reason, it is appropriate to
compare off-source sediment data to industrial risk-
based contaminants. See the Responses to Comments
11.23 and 11.31 (first bullet).
If the commentor is implying that the off-source area
is not impacted by on-source contamination, see to the
Response to Comment 11.95 for a discussion of
contaminate migration from the on-source area to the
off-source area.
11.30 Comment: Commentor states that using screening-level
soil values to screen subsurface sediment data assumes
that sediments will be routinely disturbed under the
same scenario as mentioned for surface sediments, and
that this is an unlikely scenario. [3]
Response: Subsurface sediments do not need to be
routinely disturbed for there to be a chronic exposure
condition. One excavation event or other significant
disturbance may be sufficient to permanently relocate
subsurface sediments to the surface where they would be
available for continued, chronic exposure.
11.31 Comment: Commentor stated that the screening values
used in the Risk Assessment were inappropriately
applied to the media of concern, as follows: [3]
• Human health screening values based on industrial
exposure were inappropriate to use because they
are based on long-term exposures that are
unrealistic for the off-site sediments.
Response: EPA believes it is appropriate to assume
that a person could have long-term exposures to off-
source sediments because on-source industrial
development may require access to off-source areas,
e.g., installation of utility lines in off-source areas
to support on-source development. Also, people working
at a future industrial/commercial on-source facility
may elect to use the off-source area for recreational
purposes such as fishing, hiking and kayaking on a
frequent basis.
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• . There are not enough fish in the area to sustain a
harvest needed for chronic exposure, therefore it
is not reasonable to include screening, for the
fish ingestion pathway. [also 2]
Response: The surface water criteria are based on
ingestion of "organisms" (e.g., any edible seafood,
including fish, shellfish, squid), not just fish. EPA
is not aware of any documentation supporting the
commentor's statement that there are not enough fish
available in the area of the landfill to sustain a
harvest needed for chronic exposure. The "Preliminary
Natural Resource Survey" (NOAA, 1991) prepared for the*
Tulalip Landfill Site, states on page 7:
"Habitat in the Snohomish River Delta supports
substantial fisheries. There are several large
migratory runs of salmon in the Snohomish River.
Pink, chum, coho, and chinook salmon migrate
through the area primarily from August to
December, although year-round migration occurs.
During upstream ^migration. Habitats near the site
provide critical transition habitat where salmon
must acclimate before moving from a salt
environment to freshwater migratory pathways.
During outmigration, these habitats are used
extensively by smolts and juveniles for nursery
grounds.
Commercial Catch Areas 8a and Recreational Punch
Card Area 8 are inclusive of the Snohomish River
Delta..,In general, the annual commercial salmon
catch has varied between roughly 1.0 and 1.7
million kg since 1986...An estimated 6 percent of
the recreational catch of salmon reported for all
of Puget Sound in 1988 was harvested from this
catch area".
See also Response to Comment 11.24.
• EPA used EPA Region III Risk-Based Concentrations
(RBCs) as a substitute for preparing a
comprehensive baseline risk assessment.
Response: According to CERCLA, the NCP, and EPA
presumptive remedy guidance, the streamlined baseline
risk assessment that has been completed for this Site
is appropriate and sufficient for evaluating the need
for an interim containment remedy. Use of EPA Region
III RBCs is an appropriate component of the Streamlined
Risk Assessment. The EPA guidance document
"Streamlining the RI/FS for CERCLA Municipal Landfill
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Sites (EPA, 1990a) states on Page 3 that the scope of
the baseline risk assessment can be streamlined or
limited by "identifying all pathways that are an
obvious threat to human health or the environment... by
comparing Rl-derived contaminant concentration levels
to standards that are potential chemical-specific ARARs
for the action... When potential ARARs do not exist for
a specific contaminant, risk-based concentrations
should be used." [emphasis added]. Consequently,
Region 10 used the Region 3 risk-based concentrations
because Region 10 considered the exposure assumptions
and target risk levels used in the Region 3 risk-based
concentrations to be appropriate for the Tulalip Site.
See Response to Comment 11.37.
The Streamlined Risk Assessment is not a "substitute"
for a comprehensive baseline risk assessment. The
Streamlined Risk Assessment is for decisionmaking
regarding an interim action for the containment of the
landfill on-source area; the comprehensive baseline
risk assessment will be used in deciding whether
additional clean-up will be necessary in the off-source
wetlands surrounding the landfill.
11.32 Comment: Commentor requested a detailed discussion of
the assumptions underlying the U.S. EPA Region 3
screening values and the MTCA values, including an
explanation of any changes made in the exposure
parameters used in calculating these values. [3]
Response: EPA made no changes in the Region 3
parameters or the MTCA parameters, used to calculate
risk-based concentrations, nor was any reference made
to changes. Therefore, EPA refers the reader to the
Region 3 document for complete documentation of the
derivation of these values. The reference for the
Region III values is: EPA Region III Risk-Based
Concentration Table (EPA, 1994). The reference for the
MTCA values is: Model Toxics Control Act Cleanup Levels
and Risk Calculations (CLARCII) Update (Ecology, 1995).
See the Response to Comment 11.31 (last bullet).
Following preparation of the draft Streamlined Risk
Assessment in March 1995, EPA Region 3 revised its soil
risk-based chemical concentrations. For comparison
purposes, these updated values have been incorporated
into Tables and Figures in the interim ROD, where
appropriate, and exceedances of these values were
compared to what was reported using the 1994 values.
Using the updated (1995) values, the following
exceedances were found:
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Surface Soil
Chemical Frequency of Exceedances
Aroclor 1242 2/106
Arsenic 91/93
Benzo(a)pyrene 3/106
Beryllium 2/106
Chrysene 1/106
Heptachlor epoxide 1/106
Subsurface Soil
Chemical Frequency of Exceedances
Aroclor 1242 2/19
Arsenic 17/17
Benzo(a)pyrene 3/20
See also Response to Comment 11.33
11.33 Comment: Commentor requested more documentation of the
rationale used to identify current and future exposure
scenarios, exposure pathways, and exposure parameter
assumptions. In addition, it was requested that sample
calculations be presented, showing how screening values
were derived. [3]
Response: While the Site is currently closed, the
Site, as well as surrounding areas, have been used for
recreation in the past. Potential future use scenarios
for the on-source and off-source areas were identified
in the Big Flats Land Use Program document (Tulalip
Tribes, 1994) referenced in the Streamlined Risk
Assessment. Specifically, the on-source area is
proposed by the Tulalip Tribes for industrial use in
the future, and the off-source area is proposed for use
as a "conservation" area. See Response to Comment 11.5
for a description of potential future site uses.
The Streamlined Risk Assessment also listed references
for the risk-based concentrations used. These
references contain complete documentation of equations
and exposure parameters used in computing risk-based
concentrations. Because no modifications were made to
these concentrations in preparing the Streamlined Risk
Assessment, it was not necessary to reiterate this
information in the Streamlined Risk Assessment.
Detailed information on how some of the ecological
"comparison numbers" were derived is included in the
Appendices A and B of the Streamlined Risk Assessment.
However, the November 1994 and October 1995 EPA Region
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Ill RBC Table and the MTCA RBC Tables have been added
to the AR in response to the cpmmentor's request.
Included in these tables are the exposure assumptions
and methods used to calculate RBCs.
11.34 Comment: Commentor requested that rationale be
provided for the assumption of a three percent lipid
concentration in fish in calculating water quality
standards. Commentor asked if this was a site-specific
assumption. [3]
Response: Justification for the assumption of a three
percent lipid concentration in fish is provided in
Section 3 of the Streamlined Risk Assessment in the
reference cited for the surface water comparison
numbers. The three percent lipid concentration is a
national default value (Water Quality Standards;
Establishment of Numeric Criteria for Priority Toxic
Pollutants; States' Compliance Final.Rule. 40 C.F.R.
Part 131, December 22, 1992), not a site-specific
assumption.
-**''"""
11.35 Comment: Commentor states that the use of EPA's
conservative arsenic screening criterion of 1.6 mg/kg
not only misapplies its own guidelines, as set forth by
EPA Region 3, but is also inconsistent with the more
site-specific State of Washington clean-up regulations.
The Model Toxics Control Act has a cleanup standard of
57 mg/kg for arsenic. [3]
Response: The RBCs.for soil ingestion of arsenic at
industrial sites, as provided in the Region III RBC
Tables, was used appropriately. These values do not
constitute cleanup levels, but were used to evaluate
and identify areas at the site where exceedances
occurred. Also used for this purpose was the MTCA
Method C arsenic risk-based value of 57 mg/kg and the
background level of 7.3 mg/kg, identified by the
Department of Ecology for the Puget Sound Basin.
Throughout the Streamlined Risk Assessment, the more
conservative values were used appropriately and were
imparted greater weight in the evaluation process. For
some constituents these were MTCA values; for others,
values from the RBC Tables. See Response to Comment
11.10.
11.36 Comment: Commentor stated that according to MTCA, the
risk-based screening value for arsenic in soil is lower
than the natural background concentration. [3]
Response: The EPA risk-based concentration in soil is
lower than the established regional background
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concentration. For this reason, both the MTCA risk-
based concentration and the established regional
background concentration were used for comparison in
the Streamlined Risk Assessment.
11.37 Comment: Commentor stated that it was paradoxical that
EPA screening values for carcinogens were adjusted to a
reference risk value of 10"6 to account for the
presence of children, yet MTCA values calculated for
children under a daycare scenario use a 10"5 cancer
risk level. [3]
Response: Section 3 of the Streamlined Risk Assessment
text acknowledges the fact that different cancer
benchmarks were used by EPA, as provided in the Region
3 or MTCA Tables, to calculate risk-based
concentrations and explains why both sets of values are
reasonable to consider for the site.
In using EPA Region III risk-based concentrations,
chemical concentrations associated with target levels
of a 1CT6 cancer risk and a hazard quotient of 1.0 were
selected for each chemical. It is unlikely that EPA
would in any case select less conservative values for a
streamlined baseline risk assessment, since the effect
of the presence of multiple chemicals and media are not
taken into consideration using table values. In fact,
it is recommended by EPA Region 10 that target values
of a 10"6 cancer risk and a hazard quotient of 0.1 be
used for screening values. Therefore, it can be argued
that the risk-based concentrations used in the
Streamlined Risk Assessment were definitely not unduly
conservative for the intended"purpose.
Soil cleanup standards for "industrial" sites, provided
in WAG 173-340-745 were not considered for this site
because the Tulalip Landfill does not meet MTCA's
definition of an "industrial" site. The definition of
an "industrial" site, as defined in the December, 1995
promulgated MTCA regulation SB 6123 (i.e., the "Ports
Bill") which becomes effective in February, 1996 as
follows:
"Industrial properties" means properties that are
or have been characterized by, or are to be
committed to, traditional industrial uses such as
processing or manufacturing of materials, marine
terminal and transportation areas and facilities,
fabrication, assembly, treatment, or distribution
of manufactured products, or storage of bulk
materials, that are either:
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(a) Zoned for industrial use by a city or
county conducting land use planning under
• chapter 36.70A RCW; or
(b) For counties not planning under chapter
36.70A RCW and the cities within them, zoned
for industrial use and adjacent to properties
currently used or designated for industrial
purposes."
The Tulalip Landfill does not meet this definition.
Because the comparison of residential MTCA cleanup
standards to the site was not deemed warranted, EPA
decided to use the equations and exposure assumptions
given in WAG 173-340-740(4)(b)(iii) for
commercial/industrial sites to establish risk-based
concentrations for comparison in the Streamlined.Risk
Assessment. However, the risk-based concentrations
calculated using the parameters listed in this standard
do not represent MTCA cleanup standards because other
factors such as additional exposure pathways (other
than soil ingestion), protection of ambient water and
surface water and cumulative risks would have to be
considered pursuant to MTCA regulatory provisions.
These additional factors could render final cleanup
levels more conservative than the screening valued used
for the Streamlined Risk Assessment.
The commentor also questioned the validity of using a
target value of 10"6 (for carcinogens) for one set of
risk-based concentrations (the EPA Region III RBCs) and
10"5 for the other (MTCA RBCs) . The commentor asserted
that EPA only used the Region III RBCs because they •
were "more stringent than MTCA". In fact, the target
value used for carcinogens is only one of many
differences in the factors used to calculate the
different RBCs. EPA uses the same target value for
carcinogens for both industrial workers and residents
in order to equally protect both groups. The
differences in risk-based concentrations calculated by
EPA Region III and MTCA stems from the differences in
the assumed exposure durations, rates, ages, etc. The
factors used by both groups are default values- neither
can be said to be specific to the Pacific Northwest.
One similarity between, the risk-based concentrations
calculated by EPA Region III and MTCA are that they
both use a target value of 1.0 for noncarcinogenic
effects. The net result of the use of different
exposure factors by EPA Region III and MTCA is that
MTCA risk-based concentrations are more conservative
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for noncarcinogens and EPA Region III risk-based
concentrations are more conservative for carcinogens.
Because the assumptions used by both EPA Region III and
MTCA were determined to be reasonable for this site, it
was prudent to use both sets of RBCs for comparison in
the Streamlined Risk Assessment. See Response to
Comment 11.38.
See also Responses to Comments 11.10 and 11.31.
11.38 Comment: Commentor stated that the MTCA values
presented in Table 3-1 of the Risk Assessment document
are residential, not industrial values. Commentor
further notes that residential screening values are
inappropriate to use to evaluate future land use,
because future use of this site will not be
residential. [3]
Response: EPA has not used any residential comparison
numbers in the Streamlined Risk Assessment. The MTCA
numbers presented in Table 3-1 of the Streamlined Risk
Assessment are industrial numbers, as indicated. The
commentor has incorrectly interpreted the MTCA risk-
based concentrations. MTCA has two "industrial" risk-
based concentrations for soil. One set of
concentrations, in some industrial/commercial
situations, is derived using methodology presented in
WAC 173-340-740, Method C (the concentrations used in
the Streamlined Risk Assessment). The other
concentrations defined as soil cleanup.standards for
"industrial" are calculated using WAC 173-340-745.
Using MTCA regulations, the Tulalip Landfill site does
not qualify as "industrial" under WAC 173-340-745, but
does qualify as an "industrial/commercial" site as
described in WAC 173-340-740 (1)(c). The reviewer is
directed to WAC 173-340-740 (1)(c), where the
classification "industrial" is used to describe the
comparison numbers derived under Method C. Residential
comparison numbers were not used in the Streamlined
Risk Assessment. See also Responses to Comments 11.10,
11.37 and 11.44.
11.39 Comment: Commentor stated that Figure 3-1 in the Risk
Assessment inappropriately depicted "direct contact by
humans" as a release mechanism for contaminants. [3]
Response: The commentor has misinterpreted the
information presented in Figure 3-1. In this figure,
"direct contact" represents a process by which soil has
become contaminated from landfill waste (i.e., soil is
in direct contact with landfill waste). In this
context, it is a primary release mechanism to humans.
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11.40 Comment: Cotnmentor noted that the conceptual site
model indicated that exposure to on-source soil was not
a complete exposure pathway, but that associated text
stated future recreational use of the site was
possible. Correction of this inconsistency was
requested. [3]
Response: The commentor has accurately pointed out an
inconsistency between what is presented in Figure 3-1
and the accompanying text of the Streamlined Risk
Assessment. Figure 3-1 should indicate that exposure
to on-source surface soil is a viable exposure pathway
for current/future recreational users. However, this
inconsistency has no effect on the results of the
Streamlined Risk Assessment because there are no
comparison numbers available which address recreational
exposure. However, pursuant to MTCA WAG 173-340-
740(1) (d), cleanup levels for recreational sites shall
be at least as stringent as WAC-173-340-740 Method C
cleanup levels.
11.41 Comment: Commentor stated that the surface water
screening criteria used for 1,2-dichlorobenzene and the
soil/sediment screening value used for chlordane are
incorrect in Table 3-1 of the Risk Assessment. [3]
Response: Both values are correct as presented in the
Final Streamlined Risk Assessment.
11.42 Comment: Commentor stated on page 3-17, Section 3.3,
1st sentence, that "there were" should be deleted in
the first sentence. [3]
Response: EPA has noted the commentor's grammatical
edit.
11.43 Comment: Commentor stated that the second sentence in
the fourth paragraph on page one of the Executive
Summary should contain a caveat indicating that access
to the site does not necessarily translate to a health
concern based on chemicals identified in on-source
media. [3]
Response: EPA believes that adding the caveat
suggested by the commentor would be misleading. Many
samples taken from on-source surface water (RI leachate
seep SP01, and the five 1988 surface water samples),
and RI data from the perimeter leachate seeps exceed
comparison numbers that are considered to be protective
of human health and the environment. Therefore, EPA
has concluded that potential risks to human health and
the environment are present at the Site. In addition,
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exposure to antibiotic-resistant microbiological
pathogens, which have been found in on-source surface
water, may be a potential health concern.
11.44 Comment: Commentor stated that the soil screening
number listed for chrysene is the residential, not the
industrial screening value, and that using the
industrial screening value of 18,000 /zg/kg, no
criterion exceedance would be found. [3]
Response: No residential comparison numbers were used
in the Streamlined Risk Assessment. The soil risk-
based concentration identified for chrysene is an
industrial/commercial risk-based concentration, as
defined in WAC 173-340-740. It is not a residential
concentration.
The risk-based concentration suggested by the commentor
is for industrial sites as defined at WAC 173-340-745.
As explained in paragraph 11.10 above, the Tulalip
Landfill Site does not meet MTCA's criteria for using
the industrial standards, and so the more stringent
commercial/industrial standards at WAC 173-340-740 were
used. See Response to Comments 11.10 and 11.38.
Ecological Evaluation Comments
11.45 Comment: The commentor questioned if the list of
species identified as being on site was complete, and
requested that a reference be provided for any
ecological survey work conducted at the site. [3]
Response: The list of species at the site is based on
review .of information.sources (E&E, 1988, and NOAA,
1991) for the area. In addition, EPA REAC performed an
ecological survey in 1992 (Weston, 1992). This
reference is included in the final Streamlined Risk
Assessment document. These documents are included in
the AR for the interim ROD. The list of species is not
a complete list. Instead the list is a list of
examples of species identified as being on site based
on previous investigations.
11.46 Comment; Commentor stated that EPA made numerous
conservative assumptions regarding the current or past
presence and habitats of various organisms and species
around the site. [3]
Response: Information relating to organisms and
species at the Tulalip Site were obtained from
independent biological surveys. No assumptions were
made regarding the habitat types and organisms at the
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site. Please refer to Preliminary Natural Resource
Survey, Tulalip Landfill, Marysville, WA, National
Oceanic and Atmospheric Administration, 1991 (NOAA,
1991) ; and Draft Preliminary Site Assessment of the
Tulalip Landfill, Letter from R. Henry (Weston REAC) to
D. Charters, September 8, 1992 (Weston, 1992).
11.47 Comment: Commentor stated that the conceptual site
model was confusing and requested that separate figures
be provided for aquatic, terrestrial, and estuarine
ecosystems. Commentor further noted that no
explanation was given for how the dermal contact
pathway would be evaluated for terrestrial birds and
mammals. [3]
Response: The arrows have been modified in the
referenced Streamlined Risk Assessment (Figure 4.1) to
provide better clarification. Otherwise, EPA believes
the figure is self-explanatory. The purpose of this
model is to show interactions. Separate figures would
defeat this purpose, therefore the figure was not
changed. The small mammal and bird dermal pathway will
not be evaluated separately from other pathways because
the fur/feather barrier would prevent most of the
exposure. However, any cleaning/preening behavior that
results in ingestion of particulates that adhere to
fur/feathers is considered in the ingestion pathway.
11.48 Comment: Commentor stated that the conceptual site
model illustrates pathways of concern that are not
appropriate or even plausible for selected media.
Commentor listed the following specific concerns: [3]
• Under the terrestrial on-source soil pathway,
mammals are exposed through the ingestion of
water; the media of concern is soil, not .water for
this pathway.
Response: In the final Streamlined Risk Assessment, a
separate exposure medium exists for water,- therefore,
the ingestion of water exposure route was removed from
the on-source soil exposure medium.
• Under the leachate pathway for aquatic organisms,
ingestion of soil/sediment is listed. Because
leachate is considered a water matrix, clarify how
fish and invertebrates are ingesting soil or
sediment.
Response: Leachate contains soil/sediment particulates
and these are potentially ingested along with the
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ingestion of leachate. This pathway is especially
relevant for filter-feeding organisms such as clams.
• Clarify the above bulleted items as they pertain
to the aquatic receptors in both on-source surface
water and off-source surface water media.
Response: The exposure routes listed are appropriate
for the media listed. The exposure media are
considered all-inclusive. There may be multiple
exposure routes in an exposure 'medium. For example, in
the surface water medium, there may be ingestion of
sediment/soil particulates suspended in the surface
water. To address the range of exposure possibilities,
all potential routes were included in the figure.
See Response to Comment 11.51.
11.49 Comment: Commentor requested that the results of the
evaluation of on-source groundwater sampling be
discussed for ecological receptors. [3]
Response: The Zone 1 groundwater exits the perimeter
landfill~berm in the form of leachate; therefore, the
Zone 1 groundwater was evaluated to determine chemicals
of potential ecological concern. Zone 1 groundwater is
also driven downward into Zone 2. Zone 2 groundwater
exits into the sloughs and could adversely affect
bottom-dwelling organisms. Both Zone 1 and Zone 2
groundwater were evaluated for ecological receptors by
comparison to federal AWQC and state surface water
standards. See the Responses for Comments 11.116 and
11.117 regarding dilution and mixing zone issues.
11.50 Comment: Commentor stated that the exposure pathways
listed on page 4-1 should be presented as assumptions,
not as definitions of exposure, because some of the
listed exposure pathways are not plausible. [3]
Response: EPA disagrees. All of the exposure pathways
listed are plausible, therefore they are appropriately
referred to as "potential" pathways. It is assumed
that these exposure pathways may result in an adverse
effect from chemicals of concern at the Landfill. This
discussion is a brief synopsis of potential exposure
pathways based on current scientific knowledge in
ecological risk assessment.
11.51 Comment: Commentor requested that an explanation be
provided discussing why only certain exposure pathways
were evaluated in the Risk Assessment. In addition,
the commentor stated that there is no evidence in the
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Risk Assessment that direct contact with soil by
carnivorous rodents was evaluated, as stated in the
text. [3}
Response: Under the presumptive remedy approach, it is
"not necessary to evaluate whether the containment
remedy addresses all pathways and contaminants of
concern associated with the source" in the Streamlined
Risk Assessment (EPA, 1993a). The purpose of the
conceptual site model is to illustrate the potential
pathways for inclusion in the Streamlined Risk
Assessment. The most probable scenarios were chosen
for evaluation. For example, plant, aquatic organism
(fish and invertebrates), and small mammals were
evaluated in the Streamlined Risk Assessment. Exposure
pathways included ingestion and plant uptake/sorption.
These are both major pathways and there is literature
available to associate effects with contaminant
concentrations. Direct contact with soil was evaluated
through the ingestion pathway.
11.52 Comment: In general, the commentor either did not
agree with the "screening valuers", requested additional
"criteria" or requested additional clarification
regarding the "criteria". Also, the commentor had the
following comments on specific "screening criteria"
used in the evaluation: [3]
General Response: Table 4-1 was updated in the Final
Streamlined Risk Assessment for the Interim Remedial
Response with all the current EPA Ambient Water Quality
Criteria (AWQC), including those for both dissolved and
total metals. Average water quality values were used
for pH (7.8)' and hardness (100 ppm CaCOS) because these
values are within site-specific ranges (5.9 - 8.0 pH;
76-1171 ppm CaCO3) and are typical of most surface
waters in the U.S. New criterion values resulted in
additional exceedances; criterion changes did not
change the final results. Appendix B contains a
summary of the derivation of AWQC.
Specific Responses to the bulleted comments are
provided in order, as follows:
• The surface water marine criterion used for 1,2-
dichloroethane was incorrect.
Response: The criterion for 1,2-dichloroethene was
corrected in the final Streamlined Risk Assessment
document.
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• Marine and/or freshwater toxicity values available
from EPA for dichlorobenzenes, 2,4-dimethylphenol,
• aceriaphthene, fluoranthene, naphthalene, phenol,
DDD, DDE, aluminum, and silver are not all listed.
Response: The requested criteria were added in the
final Streamlined Risk Assessment document.
• The surface water marine criterion used for
lindane is incorrect.
Response: The criterion for lindane was corrected in
the final Streamlined Risk Assessment document.
• The pH used in the calculation of the criterion
for pentachlorophenol should be stated. Likewise,
the hardness used to calculate the criteria for
hardness-dependant heavy metals should be
referenced. Commentor stated that a hardness of
100 ppm CaC03 is low considering the salinity of
waters proximate to the landfill.
Response: Average water quality values were used for
pH (7.8) and hardness (100 ppm CaCOS) because these
values are within site-specific ranges and are typical
of most surface waters in the U.S.
• There are cases where acute criterion values are
incorrectly referenced as chronic, and vice versa.
This comment applies to values for 1,2-
dichlorobenzene, 1,3-dichlorobenzene, 1,4-
dichlorobenzene, gamma-BHC, 4,4-DDT, arsenic,
cadmium, copper, cyanide, lead, mercury, nickel,
selenium, thallium, and zinc.
Response: The listed criteria are correctly referenced
in Table 4-1 in the final Streamlined Risk Assessment.
• The use of a marine surface water criterion for
chromium based on chromium VI is inappropriate.
Commentor asked for justification for the use of
this value. Commentor stated that only chromium
III (not chromium VI) would occur in oxygenated
surface water.
Response: Specific metallic speciation studies were
not performed during the remedial investigation.
Therefore it is not known what the chromium III levels
are at the site. In addition, there is no chronic
criterion for chromium III for saltwater. EPA believes
it is reasonable to assume that the chromium VI chronic
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criteria would be protective of most aquatic organisms,
therefore it was used.
• In contrast to what is stated in the Risk
Assessment, the chronic toxicity of zinc is
affected by hardness. In addition, the commentor
noted that the most recent ambient water quality
criterion for zinc was published in 1987, not
1980.
Response: Average water quality values were used for
pH (7.8) and hardness (100 ppm CaCO3) because these
values are within site-specific ranges and are typical
of most surface waters in the U.S. Reference to the
AWQC 1987 zinc document is note'd, however the process
of deriving AWQC has not changed.
• EPA incorrectly stated that aldrin levels exceeded
EPA ambient water quality criterion. Aldrin
levels exceed the Washington standard, but not the
EPA standard.
Response: There are no EPA chronic criterion for
aldrin; however, there are EPA chronic criteria for
dieldrin. Because aldrin is metabolically converted to
dieldrin by aquatic organisms, toxicity is attributed
primarily to dieldrin. The Washington state water
quality criterion was used for aldrin, since there is
no EPA chronic criterion. However, aldrin levels at
the site exceeded the Washington State chronic
criterion and the EPA chronic criterion for dieldrin.
• The freshwater chronic criterion for PCBs is
incorrect.
Response: The criterion for PCBs is correct in the
final Streamlined Risk Assessment document.
• There are dissolved metals criteria available
under the Washington Water Quality standards which
should have been used.
Response: The final Streamlined Risk Assessment
document includes Washington water quality standards
for both dissolved and total metals.
• The marine chronic criterion used for heptachlor
epoxide is incorrect.
Response: The criterion for heptachlor epoxide is
correct in the final Streamlined Risk Assessment
document.
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• Marine chronic criteria was inappropriately used
to screen on-source surface water for the
following chemicals: phenanthrene, chromium,
copper, cyanide, nickel, and zinc. In addition,
marine chronic criteria was inappropriately used
to screen on-site groundwater for the following
chemicals: heptachlor, endosulfan II, zinc,
mercury, copper, chromium, lead, cyanide, and
nickel.
Response: The final Streamlined Risk Assessment has
been revised so that on-source surface water data is
compared only to freshwater comparison numbers. The
groundwater was appropriately screened against marine
AWQC because the groundwater exits into an estuarine
environment.
11.53 Comment: Commentor stated that the on-source pooled
water is ephemeral and would not sustain a balanced
community of aquatic organisms. Therefore, ambient
water quality criteria are not appropriate "screening"
tools for evaluating these waters. [3]
Response: The on-source surface water on Tulalip
Landfill consists of semi-permanent ponded and
saturated areas capable of supporting aquatic life.
Amphibian, reptilian, and aquatic organisms may be in
the ponded areas of the landfill. Obviously, there are
no salmonids in the on-source surface water; however,
it is appropriate to-screen against AWQC because the
AWQC are designed to protect a large range of aquatic
organisms. See Appendix B in the Streamlined Risk
Assessment, "Derivation of Chemical-Specific AWQC" for
more information about the AWQC.
11.54 Comment: Commentor suggested EPA inappropriately used
outdated criteria for "screening" sediment toxicity
(i.e., AETs) and should have used the current State
SMS. Commentor argued that the EPA's stated rationale
to not use the SMS due to the unavailability of dry-
weight data and total organic carbon data is invalid.
[3]
Response: The AETs and the SMS values are functionally
equivalent, therefore either value can be used
interchangeably. In Washington State, if a particular
sample has an associated total organic carbon (TOC)
value outside of the 0.5-3.0 range, AETs are used, in
addition to SMS, for comparison to site data. Because
many of the Tulalip samples have TOC numbers outside of
this range, EPA considers comparison of site data to
the AETs numbers to be an appropriate methodology.
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EPA believes comparison of site data to AET numbers is
sufficient for the Streamlined Risk Assessment. The
comparison numbers for sediment were based on the dry-
weight normalized AET concentrations (PSEP, 1988).
AETs were used in place of the Washington State
Sediment Management Standards (SMS) (Chapters 173-204
WAC) in this assessment because the site data were
reported on a dry-weight basis. The database for site
data collected during the RI was not completed at the
time of the Draft Final Tulalip Landfill Risk
Assessment for Interim Remedial Action; nor were the
Round 2 sediment data in the database (received October
24, 1995) . Sample-specific TOG normalization will be
performed in the comprehensive baseline risk assessment
to determine which samples can be compared to the SMS
(i.e., normalization can only be performed in the TOG
range of 0.5-3.0 percent).
11.55 Comment: Commentor asserted that exceedances of the
"screening values" does not de facto indicate that
"adverse affects are expected to occur." Commentor
suggested that any observations of exceedances of
"screening values" may indicate a potential for adverse
effects. [3]
Response: EPA believes that exceedances indicate a
potential for adverse effects.
11.56 Comment: Commentor had the following comments on the
shrew model: [3]
• Commentor requested an additional explanation
regarding why the terrestrial model used for
organic chemicals could not be used for inorganic
chemicals.
Response: This model probably could be developed for
inorganic chemicals. However, there were already a
number of comparison numbers available for inorganic
chemicals, so it was not necessary to develop a model
for inorganics. ^Therefore, the model was only used for
organic chemicals.
• Commentor stated that the units do not balance in
the equation used for estimating the daily soil
ingestion rate of a shrew.
Response: The equation balances. The food ingestion
rate should be 3.0 kg earthworm/kg body weight/day.
The conversion factor has already been incorporated
into the equation. For additional clarification,
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consult the associated text on page A-4 of the
Streamlined Risk Assessment.
• Commentor requested a reference to support the
assumption that the shrew diet consists of 50
percent earthworms.
Response: This was a conservative assumption as stated
in the Streamlined Risk Assessment. It is likely that
the actual percentage exceeds 50%. The Wildlife
Exposure Factors Handbook (EPA, 1993b) referenced on
page 5-3 of the Streamlined Risk Assessment lists
.earthworms, slugs, snails, and ground-dwell ing insects
as making up over 50 percent of the shrew's diet, so
50% was used in the Streamlined Risk Assessment as a
conservative assumption.
• Commentor requested clarification regarding which
units are in wet weight, and which are in dry
weight.
Response: The document has been clarified with respect
to dry weight verses wet weight. As a point of
clarification, earthworm wet weights were converted to
dry weights.
• Commentor was unable to duplicate the calculated
soil ingestion rate.
Response: The soil concentration is calculated
correctly. The equation is 3.0 (kg fresh food/day)
(daily food ingestion rate) X 0.5 (kg earthworm/kg
fresh food) (proportion of diet that is earthworms) X
0.1 (kg soil/kg dry^weight of earthworm) (amount of
soil in earthworm) =0.15 kg/kg body weight/day (soil
ingestion rate). The conversion factor is already
incorporated into the equation and the ingestion rate
is 3.0 kg earthworm/kg body weight/day. Earthworm wet
weights were converted to dry weight.
• Commentor requested clarification regarding why
the shrew food ingestion rate was different from
the shrew daily food ingestion rate.
Response: The food ingestion rate and the daily food
ingestion rate are the same. There is a range in the
daily food ingestion rate (1.3 to 4.5 times the body
weight). For the purposes of developing ecological
comparison numbers, it was assumed the shrew consumes
three times its body weight (3.0 kg earthworm/kg body
weight/day). See page A-4 of the Streamlined Risk
Assessment for additional clarification.
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• Commentor requested more information regarding the
calculation of the ecological RBCs. Commentor was
unable to reproduce the RBCs calculated for PCBs
and DDT.
Response: Examples of calculations of ecological soil
RBCs are as follows. Detailed information regarding
the derivation and calculation of ecological soil RBCs
can be found on pages A-l through A-5 of the
Streamlined Risk Assessment. The bioaccumulation
factor for PCB (20) is multiplied by the food ingestion
rate (3.0) and the soil ingestion rate (0.15) is added
to this to calculate a total daily intake. In this
case the total daily intake is 60.15 = [ (20 X 3.0} +
0.15]. The toxicity reference value (TRY) for this
chemical is 10.0. The TRY (10.0) is then divided by
the total daily intake value (60.15) to get a RBC of
0.1662 ug/kg or 166.2 mg/kg. This number is rounded to
the nearest whole number for the final RBC of 170
mg/kg.
The bioaccumulation factor for DDT (5.1) is multiplied
by the food ingestion rate (3.0) and the soil ingestion
rate (0.15) is added to this to calculate a total daily
intake. In this case the total daily intake is 15.45 =
[(5.1 X 3.0) + 0.15]. The toxicity reference value
(TRY) for this chemical is 0.1. The TRY (0.1) is then
divided by the total daily intake value (15.45) to get
a RBC of 0.0065 ug/kg or 6.5 mg/kg.
11.57 Comment: Commentor stated that the text has not shown
that plants are more sensitive to inorganics than
shrews, and therefore the shrew model should have been
^ used to derive RBCs for inorganic chemicals. [3]
Response: EPA agrees that this model probably could be
developed for inorganic chemicals. However, there were
already a number of comparison numbers available for
inorganic chemicals, so development of the model for
this purpose was not necessary. Therefore the model
was only used for organic chemicals. The sensitivity
of plants verses shrews is dependent on the chemical
being evaluated. Therefore, chemical sensitivities
were not investigated as part of the Streamlined Risk
Assessment.
11.58 Comment: Commentor requested clarification of the
statements made in Section 4.7 of the Risk Assessment.
Commentor thinks EPA has inappropriately suggested that
there is evidence of plant mortality at the Site, and
states that discussing vole survival in the context of
plant toxicity is inappropriate. Commentor also states
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that contrary to what EPA has stated, there is no
evidence of a loss of shrews at the site, and that
there is not enough scientific evidence available to
indicate that chemicals such as PCBs are affecting
organisms at a higher trophic level. [3]
Response: EPA is stating that there is potential for
adverse effects based on the chemical concentrations at
the Site. Potential adverse effects based on numerous
exceedances of risk-based criteria are discussed in the
Streamlined Risk Assessment. However, additional text,
discussing the ecological significance of exceedances
of the risk-based criteria, was added to this section
in the Final Streamlined Risk Assessment document to
clarify that potential mortality to lower trophic
levels (e.g., plants) may have a negative impact on
higher trophic levels (e.g., voles). Exposure to
higher trophic levels will be evaluated in the
comprehensive baseline risk assessment. It is general
scientific knowledge that bioaccumulative compounds
such as PCBs can adversely affect organisms in higher
trophic levels (EPA, 1993b; Weston, Weston, 1995b).
See Response to Comment 11.60.
11.59 Comment: Commentor stated that more references are
needed to substantiate the adequacy of the RBCs
selected for the protection of biota exposed to metals
in soil. Commentor asked if plants are more sensitive
to metals in the soil, as opposed to avian and
mammalian receptors who are exposed through a soil-
based food chain. [3]
Response: Comparison numbers, with associated
references, for inorganics are presented in Table A-1-.
From these references, a range of comparison numbers
were identified. From this range of comparison
numbers, an average was determined and used in the
Streamlined Risk Assessment.
In this Streamlined Risk Assessment, which relies upon
comparing site contaminant levels to comparison
numbers, EPA believes it is not necessary to evaluate
birds and mammals with respect to inorganics because
the presumptive remedy does not require all exposure
pathways or receptors to be evaluated. Because plant
comparison numbers were readily available for the
Streamlined Risk Assessment, these were used to
streamline the risk assessment. Bird and mammal tissue
will be evaluated in the comprehensive baseline risk
assessment. See Response to Comment 11.16.
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11.60 Comment: Commentor requested an explanation of what
constitutes ecological.significance for effects in
plants. '[3]
Response: Typically the mid-range of potentially
deleterious effects were chosen as RBCs. Ecological
significance in this context refers primarily to death.
Effects such as "reduced weight" would probably not be
ecologically significant. This was only chosen if
other benchmarks bracketed (were higher and lower than)
this value. Plant mortality is an example of an
ecologically significant effect. Therefore,
exceedances of these RBCs indicates that there is a
potential for adverse effects to plants (and possibly
plant consumers) at Tulalip Landfill. For example, if
copper concentrations at the site are higher than the
100 ppm benchmark, that indicates excessive toxicity to
plants, this indicates there are potential detrimental
effects at the Site from exposure to copper. There
were soil samples in the off-source soil that exceeded
the 100 ppm benchmark with concentrations of 129 and
.. 135 ppm.
11.61 Comment: Commentor asked for justification for the
assumption that terrestrial biota would be in contact
with chemicals in soils to depths up to 1.5 feet. [3]
Response: Terrestrial organisms, particularly
burrowing.organisms (mole, otter), regularly contact
soils to depths of 1.5 feet (EPA, 1993b). In addition,
burrowing activity often results in the physical
transport of deeper soils to the surface, which exposes
non-burrowing organisms as well.
11.62 Comment: Commentor stated that in contrast to what EPA
has stated, data is available for inorganic chemicals
which addresses toxicity to mammals and birds. [3]
Response: A quantitative evaluation of birds and
mammals was outside the scope of the Streamlined Risk
.Assessment. EPA expects to evaluate, quantitatively,
bird exposure and mammal tissue in the comprehensive
•». baseline risk assessment.
11.63 Comment: Commentor stated that it is inappropriate to
conclude that elevated chemical concentrations may be a
cause for the lack of sensitive species at the site.
[3]
Response: Elevated concentrations of chemicals can
adversely affect ecological organisms, especially
sensitive species (amphibians, great blue heron, mink)
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and sensitive life-stages (juvenile). For example,
mink are very sensitive to elevated PCB concentrations.
PCBs have been detected in leachate seeps, surface and
subsurface soils, fish tissue and mammal tissue at the
Site. Some of these sensitive species (amphibians,
great blue heron) have been observed in the vicinity of
Tulalip Landfill (NOAA, 1991 and Weston, 1992).
Exposure of mink to even very low concentrations of
PCBs can lead to adverse effects such as death and
reproductive failure. No population studies have been
performed to date; however, the comprehensive baseline
risk assessment for the off-source area will evaluate
the impact these chemicals may have on sensitive
organisms. In the risk assessment process only a
select number of species, trophic levels, and exposure
scenarios can be evaluated. In EPA's opinion, it is
important to be fairly conservative in evaluating the
risk associated with chemical concentrations because
not every species and life-stage can be evaluated in a
risk assessment. In the Streamlined Risk Assessment,
elevated chemical concentrations.detected at the
Landfill were compared to concentrations that cause
adverse effects in organisms. Some of the chemicals
detected at.the Landfill were at levels above these
adverse effects criteria. Therefore, there is
potential for adverse effects to both common and
sensitive species in the vicinity of the Landfill.
11.64 Comment: Commentor stated that the ecological and
biological data -collected during the remedial
>,,., investigation demonstrate that risks to: fish and
.••„*&? wiidiife at the site, both terrestrial and estuarine,
were either non-existent or negligible when compared to
the data from the background locations. [3]
Response: EPA evaluated site data collected during the
remedial investigation with regional background data in
the Streamlined Risk Assessment and found exceedances
of background. EPA did not use the site-specific
background data collected during the remedial
investigation in the Streamlined Risk Assessment
because EPA did not have-all the background data, e.g.,
(1) the clam data was not usable and new clam data had
to be generated and (2) sediments had to be re-sampled.
The site-specific background data will be evaluated in
the comprehensive baseline risk assessment. See also
Response to Comment 11.88.
11.65 Comment: Commentor stated that, as discussed in the
Tulalip Landfill Remedial Investigation report, the
bioassays that were conducted on off-site sediment
samples indicate negligible risks to aquatic life. [3]
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Response: The bioassay data will be appropriately
evaluated in the comprehensive baseline risk
assessment. See Response to Comment 11.88. However,
preliminary evaluation of RI data indicates that
sediments collected from numerous locations surrounding
the Tulalip Landfill experienced relatively high
amphipod mortality during the test. This indicates a
potential for adverse effects for organisms exposed to
sediment in the proximity of Tulalip Landfill.
11.66 Comment: Commentor asked for further clarification on
what was meant by "groundwater in the form of ponded
areas." [3]
Response: This typographical error was corrected in
the final Streamlined Risk Assessment. The phrase was
changed to "surface" water.
11.67 Comment: Commentor noted that in contrast to EPA's
data, the data available to Parametrix and the
"*• Respondents does not indicate an exceedance of chromium
and nickel in off-source surface sediment.' Commentor
asked if these exceedances were found in EPA's split
samples. [3]
•* •*
Response: Concentrations of chromium and nickel
exceeding the comparison numbers detected in EPA's
split samples, but were not found in the Respondent's
samples at levels exceeding the comparison numbers.
Minor analytical differences such as these are common
in split samples and could be the result of
heterogenicity in samples, detection limit differences,
laboratory variability, or other similar reasons.
11.68 Comment: Commentor asked for data to substantiate the
statement that organisms used to develop specific AWQC
were compared to organisms found at the site during
EPA's Response, Engineering and Analysis Contract
(REAC) investigation. Commentor also asked for
specific data to back the statement that the AWQC were
not developed considering organisms or life stages
which are sensitive. [3]
Response: EPA is not prohibited from using a
particular AWQC if the specific organism for that AWQC
is not present on the Site. If organism similar to the
organism on which an particular AWQC was developed is
present, then that is sufficient for EPA use the
associated AWQC to assess risk.
The commentor is directed to Appendix B (derivation of
chemical-specific AWQC) of the Streamlined Risk
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Assessment for more information concerning the
derivation of AWQC. To summarize, the EPA and
Washington State AWQ standards were developed to
protect a large range of aquatic organisms (many of
these are found in the vicinity of Tulalip Landfill).
The EPA REAC report (Weston, 1992) contains information
relating to specific species identified at the Tulalip
site. The AWQC are appropriate to use at Tulalip
because many of the organisms used to develop AWQC are
also found in the vicinity of Tulalip Landfill.
However, water quality criteria are not necessarily
protective of all species and all life-stages of
wildlife. The AWQC are based on available data; new
data can result in an updated criterion. For example,
as additional species are tested in response to a
contaminant, the criterion may change because
additional information is gathered. This is because
most of the criterion values are based on data from
testing a variety of common aquatic organisms. More
sensitive life-stages (i.e., juvenile) and more
sensitive organisms (i.e., amphibians can be sensitive)
are not often tested due'to lack of commercial
availability. As new tests are developed to
investigate sensitive life-stages and organisms, lower
criterion values (more conservative) can be developed.
11.69 Comment: Commentor requested that uncertainties
related to the RI data be discussed in the uncertainty
analysis section. [3]
Response: The RI data used in the Streamlined Risk
Assessment was validated by the AOC Respondents'
contractor and no problems in the data set used for
this assessment were identified. A full evaluation of
frequency of detection, detection limits, and other
data quality issues is provided in Section 6 and
Appendix L of the RI report (HLA, 1995). A brief
discussion of the uncertainties associated with the
detection limits is provided in Section 2.1 of the
Streamlined Risk Assessment. Some of the uncertainties
related Ibo use of the RI data include elevated
detection limits compared to comparison numbers (the
data did not meet detection limit goals), interferences
from salt water, and interferences from complex sample
matrices (e.g., high organic content).
Detection limits exceedances have resulted in re-
sampling of small mammals, therefore not all of the
data was available for the Streamlined Risk Assessment.
In addition, analytical errors resulted in re-
performing the clam bioassay. This included re-
sampling selected sediment stations. Analytical
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oversights also resulted in EPA re-evaluating the fish
tissue PCB results. As an example, some of the
sediment -detection limit exceedances due to salt and/or
complex sample matrices can not be lowered; therefore,
some of these samples may not be as accurate in
predicting adverse effects.
For more information regarding the "1988 data," see the
Responses to Comments 10.1 - 10.4.
11.70 Comment: Commentor asked whether EPA measured the
hardness in the ponded water on the landfill surface,
and if so why the freshwater chronic criteria were not
adjusted according to this hardness. [3]
Response: Average water quality values were used for
pH (7.8) and hardness (100 ppm CaCO3) because these
values are within site-specific ranges (5.9 pH; 76-1171
ppm CaC03) and are typical of most surface waters in
the U.S.
11.71 Comment: Commentor stated that tidal estuaries, such
as the estuary which surrounds the landfill, typically
do not contain the diverse populations that AWQC were
established to protect. Respondents disagree that
marine AWQCs should be ARARs to be used for direct
comparison to leachate seeps and Zone 2 groundwater.
EPA inappropriately denied the Respondent's request to
conduct an aquatic life survey of the site. [3]
Response: Tidal estuaries, in contrast to the
commentor's suggestion, do contain diverse ecological
communities. In fact, tidal wetlands are the most
diverse wetland systems. In addition, these areas are
often used as nurseries for sensitive., life stages, such
as juveniles and reproductively active organisms.
Organisms at a sensitive life stages are, in general,
more vulnerable to chemical exposures. Providing a
nursey for sensitive life stages is a primary function
of wetlands (i.e., providing a nursery) for a multitude
of fish and wildlife species (Mitsch and Gosselink,
1993). Aquatic species residing in the vicinity of the
Tulalip Landfill include salmon, cutthroat trout, and
aquatic invertebrates such as clams, mussels, shrimp,
and juvenile Dungeness crab (NOAA, 1991 and Weston,
1992). Terrestrial species utilizing estuarine
wetlands in the vicinity of Tulalip Landfill include
shorebirds and waterfowl, marsh hawks, osprey, bald
eagles, and small mammals. The plant species in the
area such as cattail, bulrush, and sedges provide
shelter, feeding, and nesting areas for many of these
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wildlife species. These plants also serve as a
detrital (dead) food source for aquatic invertebrates
(Mitsch and Gosselink, 1993).
Marine AWQCs are appropriate numbers for direct
comparison to leachate and groundwater data. The
Washington State Department of Ecology recommends that
surface waters with salinities greater than 10 ppt be
compared to marine AWQC, and that surface waters with
salinities between 1 and 10 ppt are to be compared to
the most conservative of the freshwater or marine
criterion32. The salinity around the Tulalip Landfill
are between 5 and 22 ppt, depending on the tide.
Review of available biological survey data {Weston,
1992; NOAA, 1991) indicate that marine organisms
inhabit the areas surrounding the Tulalip Landfill.
The presence of marine organisms is of primary
importance in the selection of meaningful water quality
criteria. The marine organisms observed near the site
are likely the primary receptors for off-site
contaminant migration. As such, use of marine criteria
for evaluating potential toxicity to these organisms is
the most relevant and appropriate, and protective,
approach.
The Respondents' request to conduct additional aquatic
survey w,ork at the Site was the subject of a formal
dispute process under the RI/FS Administrative Order on
Consent (AOC). See Response to Comment 2.10.4 for more
information regarding this dispute. In summary, EPA's
final determination, which was issued"pursuant to the
AOC, regarding this issue is that sufficient aquatic
surveys have already been conducted in the vicinity of
the Tulalip Landfill. Additional aquatic survey work
is not necessary. For more information refer to the
following documents which are included in the AR for
this interim ROD:
1. Preliminary Natural Resource Survey, Tulalip
Landfill, Marysville, WA, National Oceanic and
Atmospheric Administration, 1991 (NOAA, 1991); and
2. Draft Preliminary Site Assessment of the
Tulalip Landfill, Letter from R. Henry to D.
Charters, September 8, 1992 (Weston, 1992).
A few of the species noted in the above documents are
summarized in the first paragraph of this response.
32 \ Personal communication between Mark Hicks, Washington Department
of Ecology and Nancy Musgrove, Roy F Weston, Inc. on January 10, 1995.
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11.72 Comment: Commentor asked that references be provided
to support the use of cattail, bulrush and sedge as a
food base'for aquatic invertebrates. Commentor asked
for a definition of "food base." [3]
Response: EPA has added the requested reference to the
final Streamlined Risk Assessment document (Mitch and
Gosselink, 1993). The term "food base" has been
changed to "food source" to more explicitly indicate
that these emergent plants form a detrital (dead) food
source ingested by aquatic invertebrates.
11.73 Comment: Commentor stated that small mammals should be
included in the list provided on page 4-1. [3]
Response: EPA agrees. Small mammals were added to the
list. The reader should note that this list is not a
complete listing of all species that have been observed
at the landfill. Please refer to Comment 11.71 for
more information. Rather, the list provides some
examples of species found in the vicinity of the
landfill.
11.74 Comment: Commentor stated that additional details
.regarding the selection of sediment "screening
criteria" are not provided in-Appendix A as referenced
in Section 4.3.1. [3]
Response: The commentor is mistaken in quoting this
section in relation to the selection of sediment
screening criteria. There is no mention of Appendix A.
~ However, in the final Streamlined Risk Assessment
document, text in Appendix A has been clarified to
explain that sediment comparison numbers were discussed
in Section 4.
11.75 Comment: Commentor noted that the Apparent Effects
Thresholds (AETs) used for benzo(b)fluoranthene and
benzo(k)fluoranthene are based on Microtox data, even
though the text states that AETs based on Microtox data
would not be used. Commentor also noted that AETs
based on amphipods, oyster larvae, and benthic
abundance are available for these chemicals. [3]
Response: These numbers were changed in the final
version of the Streamlined Risk Assessment
document. Microtox data were not used.
11.76 Comment: Commentor noted that freshwater criteria were
used instead of marine criteria to evaluate
concentrations of lead and mercury in off-source
leachate and surface water. [3]
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Response: In the final Streamlined Risk Assessment
document, the referenced numbers were changed to marine
criteria and the evaluation process was repeated.
Tables 4-2 and 4-3 in the final Streamlined Risk
Assessment reflect any changes resulting from the use
of the revised ecological comparison numbers.
11.V7 Comment: Commentor asked for a reference for the
source of on-source surface water and surface soil
data. [3]
Response: On-source surface soil and surface water
data (i.e., sample numbers P1-P5) are from the 1988 E&E
report. In addition, leachate seep SP01 is on-source
and was sampled during the RI. Leachate seep SP01 had
numerous exceedances of AWQC for inorganics such as
lead, PCBs such as Aroclor 1016, pesticides such as
heptachlor epoxide, and PAHs such as phenanthrene.
11.78 Comment: Commentor offered editorial comments on Table
4-3 of the Risk Assessment and noted that sample
R1SBSB01F1 was incorrectly listed as having a vanadium
exceedance. [3]
Response: Based on data received digitally from the
Respondents, which contains validated data submitted by
the Respondents, vanadium was detected in soil at the
concentration 'identified in the report, and exceeded
the ecological comparison number. Editorial comments
are noted. Table 4-3 has been revised in the final
Streamlined Risk Assessment.
11.79 Comment: Commentor noted that although the Risk
Assessment stated that data from reference areas were
not included, the data was included in the discussion
regarding chemical exceedances in off-source surface
water. [3] .
-"f
Response: The commentor has mistakenly concluded that
off-source surface water samples were background
(reference) samples. The off-source surface water
samples referred to by the commentor were taken to
evaluate the impact of landfill contaminant discharge
on surface water near the site, not as potential
reference locations. No reference samples were used in
the Streamlined Risk Assessment.
11.80 Comment: Commentor identified references cited in the
text which were omitted from the references section.
[3]
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Response: In the final version of the Streamlined Risk
Assessment the reference section is complete.
11.81 Comment: Commentor noted that ecological toxicity
values and Toxicity Reference Values (TRVs) do not
correspond with the values for acenaphthylene and
anthracene in Table A-2 of the Risk Assessment. The
body weights and ingestion rates used for converting
dietary values to doses was requested. [3]
Response: Information contained in the table
referenced by the commentor is correct in the final
Streamlined Risk Assessment. The requested
justification is provided in the text on pages A-4 and
A-5 of the Streamlined Risk Assessment.
11.82 Comment: Commentor noted that the chronic exposure
criterion for aldrin is inappropriately labeled as
marine when it is actually a freshwater criterion. [3]
Response: The marine and freshwater criterion for
aldrin are identical.
11.83 Comment: Commentor stated that the data that exceeded
"screening levels" was in part based on comparison to
marine aquatic standards even though the surface of the
landfill is generally 10 to 14 feet above sea level and
high tide. These surface conditions will not support
marine organisms. [3]
Response: The surface water on the landfill surface
was only compared to freshwater AWQC, not to marine
AWQC as the commentor suggests.
Data Use/Interpretation Comments
11.84 Comment: Commentor asserted that the use of
unvalidated chemistry data is not appropriate. [3]
Response: All data used in the Streamlined Risk
Assessment was validated. The Streamlined Risk
Assessment states that EPA did not perform additional
quality control on the validated data submitted by the
Respondents. EPA, however, reviewed the validation
reports submitted by the Respondents. In addition, all
split sample data was validated by EPA. For a
discussion about the quality of the 1988 data, refer to
the Responses to Comments 10.1 - 10.4.
11.85 Comment: Commentors asserted that because on-source
surface water data are sufficiently old and were
collected during on-site disposal activities with heavy
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equipment present, that the data may not reflect
current conditions at the site. [2] [3]
Response: EPA agrees that surface water data collected
in 1988 may not be reflective of current site
conditions. Refer to the Responses to Comments 2.9.2
and 2.9.3 for information about how EPA considered the
1988 surface water data.
Regarding the second part of the comment which suggests
that the 1988 on-site disposal activities may have
contaminated the samples taken in 1988 and therefore,
may not be representative of current conditions at the
Site, refer to the Response to Comment 11; 7.
Subcomments: Several additional concerns with this
data were raised.
• Commentor asked if detection limits for this data
were evaluated and within risk-based concentration
levels.
Response: Detection limits were not evaluated in the
Streamlined Risk Assessment. It was not necessary to
evaluate detection limits in the Streamlined Risk
Assessment because only detected concentrations were
compared to criteria. A thorough review of detection
limits is provided in Appendix L of the Remedial
Investigation report prepared by the Respondents (HLA,
1995).
• Commentor asked what kind of off-source area data
was being referred to in the Risk Assessment, and
in which year it was collected.
Response: The off-source data that were used are
identified in Section 2 of the Streamlined Risk
Assessment. This data was collected in 1994 and 1995
during the RI (HLA, 1995) by the Respondents.
• Commentor asked where the data used in the Risk
Assessment are summarized?
Response: The off-source data used in the Streamlined
Risk Assessment are summarized in Section 4 of the RI
report (HLA, 1995) and in Section 2 of the Streamlined
Risk Assessment.
• Commentor stated that a summary table is required
in Section 2 of the Risk Assessment which
identifies the number of samples collected by
media, the frequency of detections, the range of
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detections, and average and maximum concentrations
by depth interval.
Response: This information is provided in Section 4 of
the RI (HLA, 1995). EPA believes it would be
inappropriately redundant to duplicate this information
in the Streamlined Risk Assessment.
11.86 Comment: Commentor requested that the citation for
data obtained from duplicate samples collected by EPA
be provided. [3]
Response: Copies of the validated split sample results
are available for public review in Section 3.8 of the
AR for the interim ROD.
11.87 Comment: Commentor stated that the draft Risk
Assessment did not discuss risk-based detection limits
relative to the analytical detection limits. Commentor
suggested that this information is important for
evaluating the data reliability for Risk Assessment
purposes. [3]
Response: A discussion of analyte detection limits is
contained in Appendix L of the Remedial Investigation
report (HLA, 1995). It was not appropriate to include
discussion of detection limits in the Streamlined Risk
Assessment because only detected concentrations were
compared to criteria. However, lower risk-based
detection limits would allow the addition of more
contaminants into the evaluation process.
11.88 Comment: Commentor asked why EPA did not use the
"$700,000 worth of data collected" by the Respondents
in the "screening risk assessment." And, if EPA didn't
intend to use it, why EPA required the data to be
collected? [1] [2]
Response: See Response to Comment 11.6. The data the
commentor is referring to was not used in the
Streamlined Risk Assessment because the data was not
available at the time the Streamlined Risk Assessment
was being developed. The data was not available
because'of analytical problems with the data submitted
by the Respondents. This data has been corrected to
meet Agency standards and the Agency plans to
incorporate these data into the ongoing comprehensive
baseline risk assessment. Additionally, some of the
data (e.g., bioassays) will need to be quantitatively
evaluated using statistical methods, and this type of
in-depth evaluation was outside the scope of the
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Streamlined Risk Assessment, which is a qualitative
analysis of risk.
11.89 Comment: Conservative approaches used by EPA have
biased the Risk Assessment results. EPA selected
chemicals for inclusion in the Risk Assessment that
were: (1) only infrequently detected; (2) for
concentrations so low that they could only be
estimated; and (3) for which standard laboratory and
EPA procedures indicated the constituents were not
present but for which EPA has decided to presume were
present. [3]
Response: EPA believes the results of the Streamlined
Risk Assessment are valid and sufficient for
decisionmaking purposes with regard to an early,
interim containment remedy at the Site. See Responses
to Comments 11.26, 11.84 and 11.90.
11.90 Comment: Commentor stated that the use of estimated
concentrations conservatively biased the results of the
Risk Assessment. [3]
Response: Concentrations that are estimated (J)
indicate there is a positive identification of a
particular compound, however the "real" value could be
either higher or lower than the estimate. Therefore,
no conclusion can be made regarding the compounds'
conservative or non-conservative bias. Risk assessment
guidance states that all "J'd" values should be used in
the risk assessment. In addition, these values were
validated by the Respondents.
11.91 Comment: Commentor suggested that'EPA's draft Risk
Assessment inappropriately compared individual and
maximum detected concentrations to arbitrarily selected
benchmarks and should have calculated the concentration
term as the upper 95th percentile of the mean
concentration to estimate risk. Commentor also
asserted that the Risk Assessment failed to employ
proper guidance in determining the actual risk
calculations by ignoring average exposure time, average
exposure concentrations, and the frequency of detection
of contaminants in environmental media. [3]
Response: Contrary to what the commentor has
suggested, EPA compared all detected concentrations to
comparison numbers (not just the maximum detected
concentrations). The purpose of the Streamlined Risk
Assessment was to evaluate the frequency and magnitude
of exceedances of comparison numbers that are
considered to be protective of human health and the
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environment. For this type of qualitative evaluation,
it is not necessary to calculate the upper 95th
confidence level of the mean concentration. EPA
disagrees that the comparison numbers were arbitrarily
chosen - complete justification for the selection and
use of the comparison numbers is contained Sections 3
and 4 of the Streamlined Risk Assessment.
The Streamlined Risk Assessment fully complies with
CERCLA, the NCP, and EPA presumptive remedy guidance.
Risk calculations were not prepared in the Streamlined
Risk Assessment. Therefore, the comment that proper
guidance was not used in preparing risk calculations is
incorrect. EPA included the four steps prescribed in
EPA guidance for conducting a risk assessment in the
Streamlined Risk Assessment for the Tulalip site. For
more information see the second paragraph of the
Response to Comment 11.11.
11.92 Comment: Commentor argued that the use of total metals
concentrations is inconsistent with EPA guidance. [3]
Response: The issue of the appropriateness of total vs
dissolved metal analyses was the subject of a formal
dispute^under the RI/FS AOC (Gearheard, 1995b; Findley,
1995b). See also Response to Comment- 2.11.1 and ROD
Section 11.2.1.
EPA agrees with Respondents that the AWQC promulgated
by the State, and most recently Federal Water Quality
Criteria (FWQC) measure at least some of the water
quality criteria using dissolved metals data. However,
WAC 173-340-730 (.7) (c) states " (c) ompliance with surface
water cleanup^standards shall be determined by analyses
of unfilterecf surface water samples, unless it can be
demonstrated that a filtered sample provides a more
representative measure of surface water quality."
Respondents did not demonstrate that this is the case
and, based on available information, unfiltered samples
provide a more representative measure of surface water
quality.
Quantifying total, rather than dissolved, metals
concentrations in leachate seeps is the most
appropriate approach for assessing overall exposure
(via all exposure routes including ingestion and dermal
contact) and potential ecological risks to fish and
invertebrates residing in the vicinity of the Tulalip
Landfill. EPA does not consider the filtered leachate
data to adequately characterize all potential risks to
these receptors, and thus requires that total metals
must be used for assessing such risks.
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Even though EPA's position is that total metals (as
opposed to filtered metals) are the more appropriate
concentrations to use for risk evaluations at this
Site, in the final Streamlined Risk Assessment
document, both total and dissolved metal concentrations
were compared to criteria. Using dissolved metal
concentrations, several criteria exceedances were
found.
11.93 Comment: Commentor recommended that the frequency and
magnitude of exceedances be provided. [3]
Response: This information is provided in the interim
ROD in Table 6-2 of the human health evaluation and
Tables 6-4 and 6-5 of the ecological evaluation.
11.94 Comment: Commentor requested that the number of
samples collected in surface water that measured lead
at concentrations exceeding "screening guidelines" be
provided. [3]
Response: Streamlined Risk Assessment Table 6-2 of the
human health evaluation and Tables 6-4 and 6-5 of the
ecological evaluation indicate that lead exceeded
ecological comparison numbers in two on-source surface
water samples and one off-source surface water sample.
The human health evaluation indicated that lead did not
exceed the human health comparison number. See
Response to Comments 2.10.2 and 11.76.
11.95 Comment: Commentor stated that any discussion
regarding the pattern of contaminant migration at the
site requires a supporting reference. Further, the
commentor stated that the conclusion that the site
represents a potential source of exposure and adverse
effects to receptors is not supported by specific
scientific documentation. [3]
Response: Based on the results of the- RI/FS and the
Streamlined Risk Assessment, EPA believes the
conclusion that the Landfill is a contaminant source is
clearly supported, and the potential exposure of humans
and environmental receptors to site contamination
represents a potential threat to human health and the
environment. Contaminant migration at the site is
discussed in Sections 4 and 5 of the RI report prepared
by Respondents (HLA, 1995). This report documents
chemical concentrations detected in groundwater,
leachate, and off-source soil and sediment and
discusses potential fate and transport mechanisms for
detected chemicals. Information in the RI indicates
that the highest off-source chemical concentrations are
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found directly adjacent to the landfill. The RI
includes statements such as "(T)he highest
concentration of constituents were generally reported
1 in surface soil at the point of leachate seep
discharge." (page 6-6). The conclusion that the site
represents a source of exposure and potential adverse
effects to receptors is supported, at a minimum, by the
facts that landfill leachate can be seen discharging
from the landfill berm to the surrounding environment,
that many of the same chemicals were detected in
leachate and off-source media, and that the RI observes
a chemical concentration gradient in sediments and
soils away from the seeps, and by the magnitude and
frequency of criteria exceedances reported in the
Streamlined Risk Assessment in all media, including
perimeter berm leachate and sediments and soils near
the leachate seeps.
11.96 Comment: Commentor stated that there are a number of
reasons why elevated concentrations of phenol and 4-
methylphenol in surface sediments are not suspected to
originate from the landfill. Specific reasons given by
the Commentor include the following: [3]
4P-
• The chemical concentrations associated with
exceedances were, in all cases, higher at the
mouths of tidal channels than at the base of the
berm where leachate seeps occur. Commentor states
that this reverse gradient suggests a source
external from the landfill.
Response: It is clear that the landfill is a source of
phenol and 4-methylphenol because these compounds were
detected in leachate samples. It is possible that
additional sources in addition to the landfill exist
since phenols can be produced by aerobic degradation of
aromatic organics, sewage, and wood wastes. However,
EPA has received no information which demonstrates
these exceedances are the result of sources other than
the landfill. EPA notes that neither phenol nor 4-
methylphenol were detected in the surface water
surrounding the landfill, but both were detected in the
leachate seeps. Therefore, it would be inappropriate
to conclude that the origin of these sediment
contaminants is a source other than the landfills.
• Both chemicals were found in levels above SMS at
background and reference areas, also suggesting a
source external to the landfill.
Response: The landfill was determined to be an on-
going source of phenol and 4-methylphenol since these
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compounds were detected in leachate samples.
Evaluation of background and reference areas is
currently, being performed to determine if they are
appropriate for comparison to site results. EPA
expects this evaluation will be included in the
comprehensive baseline risk assessment.
• The short half-lives of both chemicals indicate
that neither of these chemicals can be persistent
in the environment without a relatively continuous
source of replenishment.
Response: Half-life for phenols has been found to be
relatively short in laboratory treatability studies.
Based on the results of the RI/FS and the Streamlined
Risk Assessment, EPA has concluded that the landfill is
a chronic source of contaminant loading to surrounding
areas. The Landfill may be providing a continuous
source of these contaminants to the off-source
sediments.
• The physiochemical properties of phenol suggest
that it would preferentially remain in aqueous
phase. To maintain the concentrations observed in
sediments, a source of phenol with a significantly
higher concentration would be required.
Response: Phenol adsorbs moderately well to sediment,
particularly when organic carbon levels are high (such
as in the vicinity of the landfill). The leachate
seeps provide a source of phenol, and none of the
surface water samples taken in the vicinity of the
landfill contained phenol; therefore, it seems
appropriate to conclude that the phenol observed in
off-source sediments originates from the landfill.
• The concentrations found in sediments are not -. .
explained by concentrations seen i.n media
associated with the landfill.
Response: The sediment exceedances may be a result of
landfill discharges. Modeling of contaminant
concentrations across media was not performed as part
of the Streamlined Risk Assessment. However, based on
the organic carbon partition coefficient (Koc = 2884),
one would expect water concentrations of phenol to be
100 times or more lower than sediment concentrations.
This is consistent with concentrations observed at
leachate seeps.
11.97 Comment: Commentor requested that EPA provide an
explanation to support the link of off-source
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contaminants to on-source contaminants. The commentor
stated that all chemicals found in leachate were not
found in off-source media, and numerous chemicals found
in groundwater and surface water were not found in
soil. As an example, the commentor noted that acetone
and trichloroethane were found in soil samples but not
in groundwater samples. [3]
Response: The Streamlined Risk Assessment states that
site data suggests a link between on-source and off-
source contamination. As stated in the Streamlined
Risk Assessment (page ES-3, 2-4), many of the same
contaminants were detected in both leachate exiting the
landfill and in the areas adjacent to the landfill,
which is evidence that the Landfill is acting as a
source of contaminants that migrate to and persist in
off-source areas (see Table 5-1 of the interim ROD).
Additional information regarding fate and transport of
site contamination is provided in Section 5 of the RI
report prepared by the Respondents (HLA, 1995).
Acetone was detected in Zone 2 groundwater, surface
water, and leachate samples. Trichloroethane was not
detected in any samples according to the electronic
database delivered to EPA by the Respondents.
11.98 Comment: Commentor requested an explanation for
possible discrepancies in the data. Specifically, the
commentor expressed curiosity regarding why numerous
constituents were detected in groundwater and on-source
surface water, but were not present in on-source soil.
[3] *-
Response: Information regarding the discrepancies in
analytical data, trends in detections, and overall data
quality is contained in Appendix L of the Remedial
Investigation report (HLA, 1995). Some of the RI data
discrepancies were due to matrix interference and
elevated detection limits.
Generally, EPA does not require extensive sampling of
on-source soils at landfills because on-source soil
contamination is not what usually determines the remedy
at a landfill. The presumptive remedy guidance for
municipal landfills states on page 5 "(s)treamlining
the risk assessment of the source area eliminates the
need for sampling and analysis to support the
calculation of current or potential future risk
associated with direct contact" (EPA, 1993a). There
was no requirement in the AOC to study on-source soils
under the presumptive remedy approach. Therefore, EPA
has limited on-source soil data for the Tulalip Site.
Due to the limited number of on-source soil samples,
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the Agency can not draw any conclusions about why many
contaminants identified in the groundwater were not
found in 'the on-source soil.
11.99 Comment: Commentor requested references for statements
regarding the depth to groundwater at the different
locations around the landfill. [3]
Response: The reference for statements made regarding
depth to groundwater is Section 3.6.3, page 3-23 of the
Remedial Investigation Report (HLA, 1995) .
11.100 Comment: Commentor asserted that more data and
scientific justification are needed to explain why it
is believed that groundwater is discharging to the
leachate and the adjacent sloughs. [3]
Response: Adequate data and scientific justification
explaining the connection and relationship of
groundwater to leachate and the adjacent sloughs is
provided in Section 3.6.4 of the Remedial Investigation
report (HLA, 1995) and in the SAC-4 report (Colder,
1995a). Based on EPA's review of the Respondents' work
in these documents, the Agency believes that
contaminated groundwater within the landfill discharges
to the surrounding environment via the perimeter berm
leachate seeps and the Zone 2 groundwater. These
documents are included in the AR for the interim ROD.
11.101 Comment: Commentor requested references for the Zone 1
and Zone 2 groundwater data. [3]
Response: Zone 1 and Zone 2 groundwater data was
obtained from Section 4.2 of the Remedial Investigation
report (HLA, 1995). In summary, 16 volatile organic
compounds, 20 semivolatile organic compounds, 2
semivolatile indicator compounds, 3 polycyclic aromatic
hydrocarbons, 3 pesticides, and 20 metals were detected
in the groundwater samples.
11.102 Comment: Commentor suggested the following additions
and amendments: [3]
• Average concentrations, rather than maximum
contaminant concentrations, be used for comparison
to "screening values."
Response: As stated in the Response to Comment 11.91,
all detected concentrations, not just maximum
concentrations, were compared to criteria. In effect,
this means that minimum, average, and maximum detected
concentrations were evaluated.
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• "Screening values" are erroneously identified
throughout the document as criteria.
Response:' As discussed in the Section 1.1, EPA's use
of the term criteria and screening has been misleading
and EPA used the terms too loosely in the draft Risk
Assessment. Consequently, EPA adopted the term
"comparison numbers" to better describe the numbers
used in the Streamlined Risk Assessment. In compliance
with the NCP and EPA guidance, the Streamlined Risk
Assessment compares chemical concentrations found in
various media (e.g., groundwater; leachate exiting the
landfill; surface soil, water, and leachate on the
landfill surface; and sediments, and soils adjacent to
the landfill) at the Site with comparison numbers.
These comparison numbers are established standards and
promulgated criteria, and calculated risk-based
concentrations, that are generally considered to be
protective of human health and environment.
It is true the Region 3 risk-based concentrations that
EPA used in the Streamlined Risk Assessment" are not
technically criteria in the sense that they are
enforceable. However, EPA does is not required to use
only enforceable criteria to evaluate risk. EPA will
use enforceable criteria when evaluating risk if such
numbers are available. But when enforceable criteria
are not available, EPA will use risk-based
concentrations to evaluate risk. See also Response to
Comment 11.9.
• The overall range of exceedances of arsenic needs
to be provided.
Response: Arsenic concentrations exceeded human health
comparison numbers by 1 and 2 orders of magnitude.
Ecological exceedances were within one order of
magnitude. This information is provided in Figures 6-1
and 6-2, and in Tables 6-2, 6-4 and 6-5 in Section 6 of
the interim ROD.
• The presentation of results for the human health
is disorganized.
Response: The commentor did not specify how the data
appeared to be disorganized so EPA can not respond
directly to the comment or ',s „ concern.
11.103 Comment: Commentor contested that phthalates should be
caveated because they are ubiquitous in the
environment. [3]
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Response: Phthalates are ubiquitous in the environment
because they are associated with plastics, rubber, and
paint coatings. However, phthalates were not caveated
because they were also likely components of waste
present in the landfill. Phthalate compounds were
detected in both on-source groundwater and leachate
from the landfill.
It would be inappropriate to infer that because
phthalates are ubiquitous, exceedances of comparison
numbers for phthalates do not represent a potential
risk. Phthalates do not occur naturally in the
environment; their ubiquitous nature is a result of
anthropogenic sources such as the Tulalip Landfill.
11.104 Comment: Commentor suggested that Table 2-1 of the
Risk Assessment appeared to indicate that some
chemicals may not have been analyzed in certain media.
[3]
Response: The commentor has misinterpreted Table 2-1.
As the title of Table 2-1 indicates, the information
presented in the table is limited to the name of
analytes "detected", not "analyzed" in the media
sampled. For a complete listfing of analyses performed
on these media, the commentor is directed to Section 4
of the Remedial Investigation report (HLA, 1995).
11.105 Comment: Commentor asked whether PCBs or DDT were
measured in composite fish tissue samples collected
from on-site tidal channels at concentrations above the
detection limits. [3]
Response: As shown in Table 5-1 in the interim ROD,
PCBs were detected in fish tissue samples. DDT was not
detected in fish tissue samples.
11.106 Comment: Commentor asked if EPA has evaluated what the
leachate discharges are today compared to 1980, 1986,
and 1991. If so, the commentor asked, what the
differences in quality and quantity were. [2]
Response: In its review of the Draft Remedial
Investigation report (HLA, 1995), EPA requested that
the Respondents conduct the evaluation the commentor
has described (Winiecki, 1995b). The Respondents
indicated in their response to EPA's comments on the
Draft Remedial Investigation report (Flynn, 1995) that
"Due to the lack of sufficient historical data,
(leachate) trends will not be discussed in the
(Remedial Investigation) report." At this time, EPA
does not question the validity of the Respondents'
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conclusion regarding the lack of sufficient historical
data. Therefore, EPA has not conducted an independent
evaluation of any trends.
The presumptive remedy approach does not require
information about the quality and quantity of leachate
over time and, therefore, is not needed prior to an EPA
decision regarding the need for an early, interim
containment action at the Site. It is clear that the
Tulalip Landfill is a contaminant source to the
surrounding environment.
11.107 Comment: Commentor asked if the surface soil of the
landfill is contaminated. [1]
Response: The only soil samples taken on the landfill
surface were collected in 1988 during the Site
Inspection, and these samples showed detectable levels
of several organic chemicals. For a more detailed
discussion of chemicals detected in surface soil on the
landfill surface, the commentor is directed to the Site
Inspection Report for Tulalip Landfill (E&E, 1988), and
the Streamlined Risk Assessment. See also Responses to
Comments 2.9.2, 2.9.3 and 11.7.
11.108 Comment: Commentor stated that on Table 3-2 of the
Risk Assessment, benzo(a)pyrene and mercury are
inappropriately identified as detected in samples
R1SBSB08A1 and R5LSSP02, respectively. [3]
Response: Based on data received digitally from the
Respondents, benzo(a)pyrene was detected (and exceeded
comparison numbers) in sample R1SBSB08A1, and mercury
was detected (and exceeded comparison numbers) in
sample R5LSSP02.. The comment did not provide any
supporting information for its claim that the compounds
were inappropriately identified.
11.109 Comment: Commentor requested references for the data
collection programs discussed in Section 2.3, entitled
Off-Source Data. [3]
Response: These data collection programs are described
in detail in Section 2 of the RI (HLA, 1995), which is
included in the AR for the interim ROD.
11.110 Comment: The commentor requested the reference for the
tissue data collection program cited in Section 2.3.7.
of the Streamlined Risk Assessment entitled Fish
Tissue. [3]
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Response: The fish tissue data was collected as part
of the RI at the Tulalip Landfill. The validated data
was provided to EPA by the Respondents. A complete
listing of this data is contained in Section 4 of the
RI (HLA, 1995).
Background Issues
11.111 Comment: Several commentors expressed concern that a
comparison of "reference" area concentrations to
landfill media was not performed in the Risk
Assessment. Arsenic was cited as an example of a
contaminant requiring comparison to a reference area
concentration. Also, a commentor cited levels of
chemicals in fish collected in the reference areas as
another example of data that should have been included
in the Risk Assessment. [1] [2] [3]
Response: The Streamlined Risk Assessment compared
landfill site chemical analysis data to available human
health and ecological comparison numbers. This is an
acceptable streamlined approach which is consistent
with EPA presumptive remedy guidance. The Streamlined
Risk Assessment also compared site data to published
Washington State background concentrations.
Comparison of site data to reference area data was not
performed during the Streamlined Risk Assessment for
several reasons relating to the suitability of the
sampled reference areas as being representative of
background conditions. Bioassay tests on some
reference area samples failed (i.e., the test organisms
died in excessive numbers), and several organic
chemicals including PCBs, pentachlorophenol, 4-
methylphenol, and bis(2-ethylhexyl)phthalate were
detected in many reference area samples at elevated
concentrations. Data from the remedial investigation
is insufficient to determine the origin or cause of the
chemical concentrations in the reference areas, given
the dynamic nature of the Snohomish River estuary
environment and the close proximity of the reference
areas to the landfill and other potential contaminant
sources. Both the reference areas and the area around
the landfill berm are flooded during very high tides
and large storm runoff events. Flow reversals in
Steamboat and Ebey sloughs adjacent to the landfill
that occur due to landward movement of the saltwater
wedge could also transport contaminants substantial
distances upstream.
Because EPA has not determined the feasibility of using
the background data collected in the remedial
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investigation in time for completion of the Streamlined
Risk Assessment, region-specific background
concentrations for inorganics in the Puget Sound area
were used for comparison in the Streamlined Risk
Assessment. These concentrations were developed by the
Washington State Department of Ecology (Ecology, 1994)
and represent the 90th percentile concentrations for
inorganics in soil in the Puget Sound Basin.
In the Streamlined Risk Assessment, site soil data for
arsenic, aluminum, beryllium, chromium, copper, lead,
manganese, and zinc in soil were all compared to
published Washington State background concentrations.
Even though the state background level is higher than
health risk-based criteria, several exceedances were
noted for the landfill site soil using the state
. background level of 7.3 mg/kg arsenic for soil in the
Puget Sound area as a comparison number.
Given these problems with the data collected from
sample locations that were intended to be
"reference/background" locations, EPA's decision to use
region-specific background levels developed by Ecology
is a reasonable and appropriate approach which does not
compromise the validity of the conclusions in the
Streamlined Risk Assessment, nor EPA's conclusions
based on the Streamlined Risk Assessment. EPA expects
to continue evaluating whether the sample locations
intended as background/reference locations sampled are
appropriate for use in the comprehensive baseline risk
assessment. Extensive statistical evaluation of this
data will be conducted during preparation of the
comprehensive baseline risk assessment, and feasibility
of use will be determined at that time.
Evaluation of background fish tissue values was not
part of the Streamlined Risk Assessment, however, it
will be done as part of the comprehensive baseline risk
assessment.
11.112 Comment: Commentor stated that by not considering
available background data or collecting background
samples of small mammal tissues, EPA ignored its own
guidance for conducting risk assessments. Commentor
stated that the Respondents'petitioned EPA on more than
one occasion to collect additional background data, but
that EPA rejected their proposals. According to the
commentor, the logic for this rejection cannot be
reconciled either technically or based on timing. [3]
Response: EPA disagrees with the commentor. According
to the Presumptive Remedy Guidances (EPA, 1990a, 1991,
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1993a, and 1995a), EPA does not have to evaluate all
potential exposure pathways in a streamlined baseline
risk assessment. The Tulalip Landfill Streamlined Risk
Assessment followed the Presumptive Remedy Guidances
and consequently is sufficient for decisionmaking. EPA
is not able to determine which guidance the commentor
is referring to since he did not provide a reference
with his comment. See Response to Comment 11.16
The Respondents participated in RI scoping and agreed
to do the work specified in the resulting RI Work Plan.
EPA never prohibited the Respondents from collecting
small mammal background data. However, EPA did refuse
to modify the approved RI Work Plan because the data
was not needed for EPA to perform the streamlined
baseline risk assessment and the Respondents request to
collect additional data was made too late in the
process. See Response to Comment 2.9.
The commentor did not explain why he thought EPA's
"logic for this rejection cannot be reconciled either
technically or based on timing." Consequently, EPA
cannot specifically respond t£_ that part of the above
comment.
11.113 Comment: Commentors inquired about or expressed
concern about EPA's conclusions regarding patterns of
contaminant migration at the site and the relationship
of the migration patterns to chemical concentrations in
the reference/background areas. [1] [3]
Response: Chemical analysis data provided in the RI
(HLA, 1995, Section 4) clearly indicate that many
contaminants found inside the landfill (i.e., Zone 1
groundwater and leachate seep data) also occur at their
highest concentrations in soil immediately adjacent to
the seeps in the wetlands at the- base of the landfill
.berm. Relatively lower concentrations of these
landfill contaminants were found in wetland soil,
sediment and surface water at greater distances from
the landfill. Some of these s'ame contaminants were
also found in the "reference" sample locations.
The leachate seep sample results showed a significantly
higher number of detected contaminants than were found
in Zone 1 (refuse layer) groundwater, and most of the
contaminants were found in higher concentrations in the
seeps than in Zone 1 groundwater samples. Only four
monitoring wells are screened within the refuse layer
(Zone 1). Because the landfill was constructed as a
series of refuse cells separated by internal berms,
many landfill cells are not monitored by Zone 1 wells
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and could contain contaminants not reported for Zone 1
groundwater in the remedial investigation report. Some
of these "unmonitored" cells may discharge to some of
the seeps, which suggests that the leachate seep data
is the most complete available inventory of the
contaminants present within the landfill.
As discussed in the Response to Comment 11.95 above,
the environment around the landfill is dynamic; gradual
concentration gradients of contaminants away from the
landfill should not be expected. EPA believes the
remedial investigation data clearly shows that
contaminants originating from the landfill are
migrating off-site and are accumulating in the
surrounding wetlands. It remains unclear if the
contaminants present in "reference/background" area
samples are from the landfill or other sources. EPA
will further evaluate this issue in the comprehensive
baseline risk assessment.
11.114 Comment: Commentor expressed concern that the Landfill
may not be the only contributor of contamination in the
vicinity of the site, and wondered what actions EPA
will take to eliminate/control other contaminant
sources in the area. [1]
Response:'" EPA agrees that the landfill may not be the
only contributor of contamination in the vicinity of
the Site. Some of these other potential contamination
sources are regulated under other laws. Sewage
outfalls, for example, are required to obtain and
comply with National Pollution Discharge Elimination
System (NPDES) permits under the Clean Water Act. It
is outside the scope of the Superfund process to
evaluate and regulate all of the possible contaminant
sources to the watershed in which a Superfund Site is
located.- However, by minimizing the contaminant
contribution from the Tulalip Landfill to the
surrounding areas, EPA expects that implementation of
the selected interim remedy will result in reduced
exposure of people and ecological receptors to
chemicals exceeding comparison numbers at levels that
are considered protective of human health and the
environment. Contaminant loading due to landfill
discharges would also be greatly reduced. Therefore,
EPA concludes that implementation of an appropriate
remedial action is necessary.
11.115 Comment: Commentor stated that EPA is ignoring its own
guidance relating to the concept of "clean islands" by
not considering background concentrations in the
"screening level" risk assessment. [3]
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Response: The commentor did not provide a reference to
the guidance to which the comment refers; therefore,
the Agency can not respond specifically to the
commentor because EPA is not sure what the commentor
means by "concept of 'clean islands.'"
The remediation of the Tulalip Landfill is required not
only because the landfill is contaminated but also
because the Site is a source of contamination to off-
source areas. The purpose of the remedy selected for
the Site is to minimize the continued release of
contaminants into the environment from the landfill.
EPA evaluated site data collected during the remedial
investigation with regional background data in the
Streamlined Risk Assessment and found exceedances of
background. EPA did not use the site-specific
background data collected during the remedial
investigation in the Streamlined Risk Assessment
because EPA did not have all the background data, e.g.,
(1) the clam data was not usable and new clam data had
to be generated and (2) sediments had to be re-sampled.
The site-specific background data will be evaluated in
the comprehensive baseline risk assessment. See also
Response to Comment 11.88.
Dilution/Mixing Zone Issues
11.116 Comment: Several commentors stated that AWQC were
inappropriately applied to leachate in the Risk
Assessment because a mixing zone was not allowed.
Commentors asserted that surface water collected in the
areas adjacent to the landfill has chemical
concentrations below marine AWQC, indicating that
leachate is sufficiently diluted_to prevent a problem.
One commentor stated that the concentration of
contaminants should be measured in the media in which
the receptors live. Commentors stated that it is
inappropriate to screen leachate directly against
marine AWQC because leachate must mix with surface
water to attain the salinity necessary for survival of
marine organisms. The commentor further stated that
direct exposure of fish to leachate concentrations is
not possible. [1] [2] [3]
Response: For the purposes of the Streamlined Risk
Assessment, EPA chose to make an appropriately
conservative assumption that bottom dwelling organisms
residing in areas adjacent to the landfill would be in
direct contact with leachate and groundwater. A mixing
zone is inappropriate at the Tulalip Landfill because
many organisms that EPA believes should be protected at
the Site do not live in the water column. Many
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organisms at the Site, such as amphipods, clams and
sculpin, live in or frequently inhabit the sediment and
are therefore likely to be directly and regularly
exposed to undiluted concentrations of landfill
contaminants in leachate or discharging groundwater
when there is no "clean" estuarine water available for
mixing and dilution because the tide is out. It is
appropriate to be relatively conservative in evaluating
the risk associated with chemical concentrations in an
estuarine environment because not every species and
life-stage is accounted for in the AWQC or can be
evaluated in a risk assessment.
On February 17, 1995, the Respondents to the 1993 AOC
for the conduct of the RI/FS invoked dispute resolution
under paragraph 61 of the AOC with respect to a number
of issues including the use of mixing zones for
measuring compliance with AWQCs. On October 18, 1995,
EPA's Region 10 Deputy Regional Administer issued a
final determination that concluded that a mixing zone
would not be used for measuring compliance with AWQC.
(Findley, 1995b; Gearheard, 1995b). EPA's position is
consistent with the Washington state regulations that
are appropriate for the Site. WAC 173-340-720(6)(d)
states that the mixing zone concept cannot be used
pursuant to MTCA to determine the point of compliance
for leachate contaminated groundwater discharging to
surface water. Under the CWA and WAC 173-201A-040(3),
the term "surface waters" .includes wetlands, tidal
channels, and mudflats: the kind of landscape found
around the perimeter of the landfill. Results of the
RI indicate that leachate is regularly discharging
directly onto the wetlands and mudflats that surround
the landfill. See also interim ROD Section 11.2.1.
Direct exposure of bottom-dwelling fish such as the
staghorn sculpin to leachate chemical concentrations^is
also possible because sculpin pr other bottom-dwelling
organisms may receive direct exposure to undiluted
leachate during periods of low tide. Sculpin also have
a behavioral adaptation of burying into the sediment
during periods of low tide that would increase the
organisms' chance of exposure to undiluted flowing into
the sediment.
11.117 Comment: Commentor indicated that, to their knowledge,
all previous studies were conducted in the main slough
near the site and these studies do not reflect on-site
conditions. If these surveys are accepted, the
commentor requested that EPA allow sufficient dilution
for the leachate to reach these distant sloughs and
tidal channel locations. [3]
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Response: The EPA REAC study (Weston, 1992) evaluated
the landfill surface, tidal channels, off-source
wetlands,' and the sloughs. The Respondents also
evaluated the sloughs (Ecology and Environment, 1988).
In addition, AOC Respondents seined the tidal channels
in the off-source area during the remedial
investigation and captured marine and estuarine
organisms. A dilution factor is inappropriate because
of the reasons stated in the Response to Comment
11.116.
12.0 COMPREHENSIVE BASELINE RISK ASSESSMENT
12.1 Comment: Commentor indicated that statements provided
in EPA guidance documents and the preamble to the NCP
are not promulgated regulations or laws themselves, and
therefore they can't be used to justify not conducting
a comprehensive baseline risk assessment, as is
required by the NCP language itself. [2]
Response: EPA disagrees with this comment. Refer to
the Response to Comment Sections 2.1, 2.2, 2.3 and
2.5.5.
EPA believes that its use of unpromulgated guidance
documents to help guide EPA's decision-making process
is justified. The purpose of EPA guidance is to
provide EPA employees with a tool they can use to
ensure that their decision-making processes at
Superfund sites are consistent with CERCLA and the NCP.
As part of that function, the guidance documents also
assist EPA employees with their interpretation of the
requirements of CERCLA and the NCP. These guidance
documents are written by EPA personnel who are
knowledgeable in a particular subject area and who have
experience in dealing with issues that arise in that
particular area. Thus, EPA believes that the use of
guidance by EPA personnel is appropriate to ensure
decisions that are made are consistent with CERCLA and
the NCP.
12.2 Comment: Commentors stated that a comprehensive
baseline risk assessment needs to be performed to
establish the need for anything beyond the no-action
alternative. Also, a commentor wanted to know if the
comprehensive baseline risk assessment would be
conducted and how long it would take. [2]
Response: Refer to the Responses to Comments 2.1, 2.2,
and 2.3 for a Response to the first sentence. EPA
plans to begin the comprehensive baseline risk
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assessment in the Winter of 95/96 and expects that the
comprehensive baseline risk assessment may take
approximately 9 months to complete.
12.3 Comment: Commentors stated that a comprehensive
baseline risk assessment which incorporates site-
specific information and assumptions should be used to
establish the need for remedial actions. [2] [3]
Response: Refer to the Responses to Comments 2.1, 2.2,
and 2.3.
12.4 Comment: Commentors stated that the Risk Assessment
for interim containment remedy is only a "screening
level" risk assessment which substantially
overestimates risk, and may in fact estimate risk that
does not exist. Commentors stated that only a
comprehensive baseline risk assessment estimates risk
at the level of detail necessary to make final remedial
decisions, and that, until the comprehensive baseline
risk assessment is conducted, it is impossible to
accurately assess the potential risks at the Tulalip
Landfill. [2] [3]
Response: The Streamlined Risk Assessment estimates
risk in a reasonable manner in accordance with EPA
guidance on risk assessments for presumptive remedies.
The Streamlined Risk Assessment is appropriate for the
purpose of supporting EPA decisionmaking regarding
whether an interim remedial action should be conducted
at the Site, and, if so, what the remedial action
should be. Many of the ecological comparison numbers
used in the Streamlined Risk Assessment are effects-
based concentrations values [the value used has a
demonstrated negative response in the target
receptor(s)]. Additionally, many of the ecological
comparison numbers were in the mid-range of the
gradient of adverse effects, which provides a more
realistic estimation of risk.
The predicted toxicity of contaminants in the leachate
seeps and groundwater has been evaluated using standard
approaches (comparison with available criteria,
standards and risk-based concentrations). In the
absence of actual data concerning risk to wildlife or
benthos, a reasonable conservative approach was taken.
Existing data from the Tulalip Landfill show clear
indications of toxicity from landfill sources. At
leachate seeps in particular, DDT and two Aroclors
(1016 and 1232) had exceedances of 13 to 49 (DDT), 16
to 40 (Aroclor 1016), and 33 to 194 (Aroclor 1232)
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times the water ecological quality criterion,
respectively. These consistent, high level exceedances
underscore the concern that leachate seeps represent an
ongoing source that loads these persistent and
bioaccumulative contaminants into the surrounding
ecosystems. Of similar concern is mercury, which had
concentrations in the leachate up to 15 times the water
quality criterion. Even though these concentrations
are likely to decrease with distance from the seep
source, constant loadings could maintain the presence
of these compounds in the surrounding media.
Without uptake data based on receptors present in the
wetlands and sloughs, or detailed information on fate
and transport, the linkage between landfill discharges
and long-term loading that will affect environmental
receptors can only be'estimated. What has been clearly
demonstrated, however, is that the landfill discharges
contain contaminants in relatively high concentrations
(i.e., exceeding water quality criteria) that are known
to bioaccumulate and persist. In addition, these
contaminants appear to be widespread at the landfill.
For example, DDT and PCBs were found at numerous
leachate sources (7 of 11 sources and 11 of 11 sources,
respectively) at concentrations exceeding ecological
water quality comparison numbers and present an ongoing
pervasive threat to the nearby receptors.
12.5 Comment: Commentor asked if additional risk assessment
information would be made available before the
selection of the-remedy. [1]
Response: EPA plans to begin the comprehensive
baseline risk assessment in the Winter of 95/96. The
comprehensive baseline risk assessment will be used in
the selection of the final off-source remedy at the
Site. However, the comprehensive baseline risk
assessment*wall not be completed before the ROD for the
interim remedial action at the Tulalip Site is issued.
12.6 Comment: Commentor stated that the Risk Assessment
should discuss risk-based reporting limits and
exceedances thereof, and, in particular should discuss
how chemicals exceeding risk-based detection limits
were handled in the Risk Assessment. [3]
Response: It was not necessary to include discussions
of risk-based reporting limits in the Streamlined Risk
Assessment because only detected concentrations were
used in the analysis. Undetected chemicals were not
included in the Streamlined Risk Assessment. EPA
believes this to be an appropriate and acceptable
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approach for a streamlined risk evaluation at this
Site.
13.0 SELECTION OF PRESUMPTIVE REMEDY/REMEDIAL ALTERNATIVES
13.1- Comment: The commentor supports the preferred remedy
(Alternative 4c) because the remedy fulfills the
requirements of the NCP. The remedy achieves
protection of health and the environment; complies with
ARARs; is a proven technology; and is a cost-effective
way to achieve statutory requirements of CERCLA, and
the RAOs. Other alternatives may have lower capital or
O&M costs, but they do not meet threshold requirements
of CERCLA and the NCP (e.g., they are not protective of
health and the environment, do not comply with ARARs).
The commentor prefers the selected remedy because the
remedy also achieves substantial risk reduction, is the
least expensive remedy in the long-term, and will
significantly reduce migration of hazardous substances
into marine waters. The commentor stated that the
selected remedy is the most implementable remedy.
While the commentor generally supports EPA's analysis
of alternatives, they believe EPA under-emphasized the
true performance and benefits of the capping
alternatives (e.g., the cap prevents leachate
production which is clearly preferable to treating
leachate). The commentor also supports the low-
permeability cap to stop the generation and flow of
contaminated leachate. Using the Respondents own
modeling efforts, the 4c alternative will result in a
greater than 99% reduction in the generation of
leachate. Prevention of the generation of leachate is
preferable to alternatives that do not include a low
permeability cap. ...... •
The commentor expressed doubt that the treatment berm
(Alternative 2a) would perform as well,as the party
that proposed it has stated. The commentor indicated
that the "treatment berm alternative" proposed by the
PRPs was flawed and the "Terminal 91 analogy is clearly
false". In addition, the commentor stated that Dr.
Greg Richardson, consultant for the Tulalip Tribes,
indicated that the Terminal 91 solution was dilution
(an unacceptable solution). He further stated that the
treatment berm alternative does not address elimination
of contaminant pathways (plant uptake, direct human
exposure, methane gas release) that occur on the
surface of the landfill. The commentor stated that he
submitted extensive comments on August 17, 1995
regarding the use of a treatment berm remedy.
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The commentor opposes the treatment berm (Alternative
2a) because: the filter design will not function and
the approach is based on a dilution strategy which does
not mitigate environmental loading of landfill
contaminates/ and the trenching technique may increase
risk to the environment. The commentor has concerns
about both short and long-term performance of the
treatment berm. The commentor asserted that data that
has been submitted in support of the treatment berm is
not applicable to the Tulalip Site because the Terminal
91 Site is different from Tulalip. In addition, the
commentor states that the treatment berm alternative is
not as cost-effective as EPA's selected remedy.
In summary the commentor, stated that EPA's proposed
interim remedial action is the most direct method and
least expensive viable remedial action alternative to
dramatically reducing leachate generation at the
landfill. Furthermore, the commentor stated that
Tulalip Landfill is ideally suited for the presumptive
containment solution developed by EPA. [10]
Response: Comment noted.
13.2 Comment: Commentors expressed support for EPA/s
preferred .alternative, 4c, Geosynthetic Cover with
Passive Drainage, as being the only remedial
alternative that will protect the estuary. The
commentor opposes the No Action alternative and the
hydraulic collection system alternative (identified as
2b in the Proposed Plan). Commentors stated that they
do not believe that the hydraulic collection system
will function over the long haul. Also the commentor
concluded that the system appears to be an elaborate
dilution technique and that dilution is not the
"solution to pollution." [7] [11]
Response: EPA agrees with the commentor that the No
Action Alternative and the 2b alternative are not
viable remedial alternatives for the Tulalip Site. EPA
only includes a No Action alternative in the
Feasibility Study and Proposed Plan for purposes of
comparison with other alternatives. EPA is also
concerned with the potential long term viability of
Alternative 2b. EPA has a number of concerns with
Alternative 2b, including that the system will clog and
require continual maintenance at yet undetermined
costs. The party that proposed the 2b alternative did
not submit to EPA persuasive information indicating
that the proposed "treatment berm" would indeed treat
leachate, as opposed to simply diluting out the
contaminants in the leachate to undectable levels and
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then releasing the contaminants into the environment.
EPA is concerned that dilution would allow continued
environmental loading of the contaminants in the
wetlands and sloughs surrounding the Site.
13.3 Comment: The commentor conducted a complete review of
the RI/FS Report and agrees with its conclusions. The
commentor states that it is imperative to stop the
leaking of hazardous substances permanently and
completely. [7] [16]
Response: Comment noted.
13.4 Comment: Commentor asked how long it will take to
construct the preferred Alternative 4c. [1]
Response: Remedial design and construction is expected
to take about 2 years.
13.5 Comment: Commentor asked how long it will take before
leachate seeps associated will the landfill are
eliminated. [1]
Response: According to the feasibility study,
implementing Alternative 4c would effectively eliminate
rainfall infiltration 33 and reduce leachate
generation, thereby eliminating seep groundwater
discharges. Discharges of most leachate through the
seeps would be expected to diminish in as few as two
years.
13.6 Comment: Commentor asked how long the Alternative 4c
cap is expected to last. [1]
Response: Landfill caps that have a geosysthetic
component have been in use for the past two decades,
and have become the standard in landfill closures. The
longevity of the geosynthetic material can be predicted
using an accelerated aging test, during which the
material is subjected to intense temperatures, high
stress, and various liquids. The studies indicate that
geosynthetics can last almost indefinitely, assuming
proper maintenance and that all the components of the
cap are properly installed.
33 EPA notes that all low-permeability covers develop leaks over time, so
infiltration will never be completely eliminated. However, with proper
construction design, materials, techniques, quality assurance, and operation
and maintenance, the number of leaks are minimized.
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13.7 Comment: Commentor stated that the Tulalip Tribes
support option 4c, and expressed concerns regarding
option 2b because it is an unproved technology and
would require more monitoring than 4c. The commentor
further indicated that, in his opinion, the
comprehensive baseline risk assessment will do nothing
but further delay what the Tribe has been seeking for
the past 25 years, which is to have'the site capped.
The commentor states that food fish and wildlife are in
direct contact with contaminants from the site and are
consumed by members of the Tribe. [2]
Response: Comment noted.
13.8 Comment: Commentor indicated that leachate is the
primary risk that EPA has characterized. Commentor
suggests that eliminating leachate generation is the
preferred approach to control site risks and suggests
that a low permeability cap is the standard solution to
eliminating leachate. The commentor was opposed to the
leachate collection and treatment approach due to high
operating costs. Commentor stated that alternative 4c
is the least costly alternative that would be
protective of the environment and comply with NCP
criteria. [2]
Response: Comment noted.
13.9 Comment: Commentor suggested that a low-permeability
cap is the common-sense technology for landfills in
western Washington. The commentor indicated that he
was unaware of any landfills west of the Cascade
Mountains that contain similar wastes and were closed
without the use of a low-permeability cap. This, the
commentor stated, is because landfills west of the
Cascades receive high levels of precipitation. It is
the opinion of the commentor that the use of a low-
permeability cap is the most logical and applicable
remedy. [2]
Response: Comment noted.
13.10 Comment: The commentor ideally would like the site
capped with an impermeable cap and a leachate
collection system. The commentor felt the leachate
collection system was necessary in case of cap failure
or catastrophic precipitation events. In the event of
insufficient funding, the commentor thought the EPA
selected remedy would be protective. [7]
Response: EPA concedes that installing a low-
permeability cover at the Site, in conjunction with a
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leachate collection system, would be more protective
than the selected Alternative 4c, which only includes a
low-permeability cover. Alternative 5 would be more
protective, especially if the leachate collection
system was constructed prior to the cover, because the
leachate collection system would likely stop the
ongoing flow of leachate through the perimeter berm
within one year. However, in EPA's view, Alternative 5
is not as cost-effective as Alternative 4c because the
incremental environmental benefit of the leachate
collection system is not justified by its increased
cost. The reason for this is that the groundwater
modeling conducted by the Respondents during the RI/FS
indicates that the selected Alternative 4c, will cause
the leachate seeps to essentially "dry up" within 2
years of construction completion, by cutting off the
infiltration of surface water into the landfill which
feeds the seeps. The cost difference between
Alternative 4c and Alternative 5 is approximately $3.2
million. EPA does not believe it is cost-effective to
pay .$3.2 million to install a leachate collection
system that may become unnecessary within 2 years. • A
better approach is to install the low-permeability
cover required by 4 and wait and see whether the
leachate stops flowing in 2 years as expected. If it
keeps flowing, at unacceptable levels, a leachate
perimeter collection system could be added in the
future.
13.11 Comment: The commentor supports the leachate
collection and treatment alternative rather than the
EPA selected alternative of capping the Site. The
commentor concludes that the data does not warrant a
cap and that all available data should be analyzed.
Also the commentor states that objections to leachate
collection and treatment system such as lack of waste
containment could be addressed by the use of
institutional controls. [12]
Response: EPA believes a cap for the site is
preferable to a leachate collection system because a
cap prevents the generation of leachate while a
leachate collection system only collects leachate which
then'must be transported off site for treatment. EPA
has concluded that alternatives 2b and 2b(ii) do not
meet the two threshold criteria: overall protection of
human health and the environment, and compliance with
ARARs. See Section 9.0 - Summary of Comparative
Analysis of Alternatives in the interim ROD. See also
Appendix A in the interim ROD. EPA has identified a
number of uncertainties regarding the leachate
collection system proposed by Respondents, specifically
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Alternative 2b(ii). See Appendix E for a more detailed
assessment by EPA of Alternative 2b(ii). See also
Memorandum, Eric Winiecki to The File, August 4, 1995,
re: EPA Review of Alternative 2b - Treatment Berm" in
the AR for this interim ROD (Winiecki, 1995d).
EPA has determined that the data from the RI/FS,
including the Streamlined Risk Assessment, indicates
that a containment response is necessary for the
Tulalip Site. For details, refer to the Responses to
Comments 2.16 and 13.13. EPA conducted an analysis of
alternatives using the nine criteria specified in the
NCP and determined that the least expensive alternative
that would meet EPA's threshold criteria was
Alternative 4c - the landfill cap. EPA has eliminated
the leachate collection and treatment system proposed
by the Respondents because of serious concerns that EPA
has regarding.the effectiveness and implementability of
the system (in addition to the system failing to meet
the NCP threshold criteria). The use of institutional
controls will not address EPA's effectiveness and
implementability concerns. The commentor did not
identify specific institutional controls, so EPA can
only speculate on what the commentor may have been
referring to in his comment. Institutional controls
(such as access restrictions due to fences) would
perhaps mitigate human contact with the surface of the
soil but would not control the flow of contaminated
leachate into the neighboring wetlands, nor would they
prevent wildlife from entering the landfill.
An EPA guidance for selecting remedial actions, "A
Guide to Selecting Superfund Remedial Actions" (EPA,
1990b) states on page 1 "(i)nstitutional controls are
most useful as a supplement to engineering controls for
short- and long-term management. Institutional
controls (e.g., deed restrictions, prohibitions of well
construction) are important in controlling exposures
during remedial action implementation and as a
supplement to long-term engineering controls.
Institutional controls alone should not substitute for
more active measures (treatment or containment) unless
such active measures are found to be impracticable."
Because institutional controls have a very limited
value in mitigating risks of concern at the Tulalip
Site, EPA directed the Respondents to eliminate
institutional controls as a stand-alone alternative
during development of the SAC FS. The Respondents
subsequently initiated a formal dispute resolution
process under the AOC regarding institutional controls
as a stand-alone alternative. EPA later issued a final
determination, in accordance with the AOC, which found
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that EPA had "provided a reasonable basis" for its
position and that "this position (was) consistent with
EPA's discretion, under CERCLA, the NCP, and the
agreements made in the AOC."
13.12 Comment: Even the Tribes' consultant, Dr. Gregory
Richardson, says that the less costly leachate
collection and treatment remedy would perform as well
and provide the same level of protection more quickly.
[6] [8]
Response: EPA is unaware of any statements or
documents made by Dr. Richardson that states "that the
less costly leachate collection and treatment remedy
would perform as well and provide the same level of
protection more quickly." The commentor did not
provide a reference to statement allegedly made by Dr.
Richardson's, therefore, EPA cannot respond
specifically.
A review letter from Dr. Richardson was submitted with
public comments from The Tulalip Tribes on October 20,
1995. In that letter Dr. Richardson states "I feel
that the proposed interim remedial action proposed by
EPA is the most direct method to dramatically reduce
future leachate generation at the Tulalip Landfill.
Additionally, the proposed remedial action is the least
expensive of viable remedial action alternatives in my
opinion. The Tulalip site is ideally suited for the
presumptive containment solution developed by EPA."
Dr. Richardson also clearly stated on several occasions
while making his oral comments during the October 3,
1995 Tulalip landfill public meeting that "providing a
cap, preventing the generation of leachate, has always
been much less expensive than the treatment of leachate
and collection of leachate" (Northwest Court Reporters,
1995). . * -
13.13 Comment: Commentor stated that the proposed
Alternative 2b would achieve remedial action objectives
sooner than Alternative 4c. [2]
Response: EPA's evaluation of whether a remedial
alternative is expected to meet the cleanup objectives
for a remedial action is an important consideration
under the NCP threshold evaluation criterion: "Overall
Protection of. Human Health and the Environment." The
Remedial Action Objectives (RAOs) that EPA has
identified for this interim action are described in the
interim ROD in Section 7.0 - Cleanup Objectives for the
Interim Remedial Action. Based on the results of the
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RI/FS, the findings in the Streamlined Risk Assessment,
and public comments received during the public comment
period, and further EPA review and re-evaluation of all
the alternatives under consideration, EPA has concluded
that Alternatives 2b and 2b(ii) may not meet, or do not
meet, all of the Remedial Action Objectives (RAOs)34.
EPA believes there is considerable uncertainty
regarding whether Alternative 2b and 2b(ii) would meet
the following RAOs:
• Zone 1 Leachate: Eliminate migration of leachate
that exceeds potential surface water ARARs from,
through, and/or under the source area berm.
Alternative 2b may not meet potential surface
water ARARs at the face of the proposed "treatment
berms" if the berms are not effective.
EPA has expressed concern that there was
insufficient justification to conclude that the
leachate collection system proposed for
Alternative 2b would meet the RAO to eliminate the
leachate seeps35. EPA indicated that additional
information would be needed to support the
Respondents' claim that Alternative 2b would
eliminate the migration of leachate that exceeds
surface water ARARs from, through, and/or under
the source area berm. EPA also expressed concern
about the implementability and long-term
effectiveness of the Alternative 2b system. The
Respondents' subsequent submittal of Alternative
2b(ii) to EPA, which employs a similar collection
system, does not provide the requested
justification.
In contrast, groundwater modeling conducted by the
Respondents during the FS (Colder, 1995a) suggests
that the selected alternative, 4c, would be
expected to attain this RAO within two years. EPA
considers the groundwater modeling results for the
cover alternatives to be more certain because
landfill covers are a proven technology with known
effectiveness. Implementation of Alternative 4c,
would attain this RAO by reducing the Zone 1
34 See Memorandum, Keith Pine of Weston to Eric Winiecki of EPA,
February 6, 1996, in the AR for this interim ROD,
35 See EPA's comments on Alternative 2b, transmitted in a letter from
Eric Winiecki of EPA to Anthony Burgess, Colder, August 3, 1995, in the AR for
the interim ROD.
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leachate mound, causing the perimeter berm
leachate seeps to cease flowing within 2 years of
construction completion.
Zone 2 groundwater: Minimize migration of
contaminated groundwater at levels exceeding
background concentrations or surface water ARARs,
whichever is less stringent, and prevent use of
contaminated groundwater.
Alternatives 2b and 2b(ii) may not meet surface
water ARARs at the sloughs if the unproven
collection systems are not effective.
In addition, according to the Respondents'
predictions based on groundwater modeling, it is
clear that the selected alternative would minimize
the migration of contaminated ground water to a
significantly greater extent over the long term.
See Response to Comment 2.10.1.
In contrast, the Respondents' groundwater modeling
shows that Alternative 4c is expected to
effectively stem the migration of leachate from
the landfill over the long term. Alternative 4c
performs significantly better than Alternatives 2b
and 2b(ii) in this regard after about the first 5
years based on predicted annual leachate flux
(Colder, 1995b, Figure 4-1)36.
Landfill_gas: Prevent inhalation and release of
landfill gas exceeding ambient air standards
established by the Puget Sound Air Pollution
Control Authority (PSAPCA), and manage the gas to
prevent stress on a cap system.
Alternatives 2b and 2b(ii) would not ensure that
the first part of this RAO would be met. In
general, gas production within landfills can
stress vegetation growing on or near the site,
result in a potential threat to public safety, or
create an odor nuisance. Landfill gas is
potentially explosive at certain concentrations,
and usually contains hazardous substances. PSAPCA
regulations provide requirements for allowable gas
emission rates, air emissions detrimental to
persons or property, and odor and nuisance control
measures.
36 For the convenience of the reader, Figure 4-1 is included in
Attachment B of this Responsiveness Summary.
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Current landfill emission of methane gas at the
Tulalip Landfill is estimated to be 228,000,000
cubic feet per year (HLA, 1994). The current rate
of gas production at the Site may be suppressed
because much of the waste is within the Zone 1
leachate mound, and therefore much of the waste is
saturated, which would be expected to impede waste
decomposition which produces landfill gas.
However, if the leachate mound in Zone 1 were
lowered as a result of installing the collection
systems proposed for Alternatives 2b or 2b(ii),
the rate of landfill gas production could
substantially increase as more of the waste
becomes unsaturated and begins to decompose.
Thus, while implementation of Alternatives 2b or
2b(ii) could create or worsen a landfill gas
problem at the Site, these alternatives do not
provide for the possible need for gas collection
and treatment.
EPA expects that Alternative 4c, which includes a
landfill gas collection system and a contingent
gas treatment system, would ensure that this RAO
will be met.
Alternatives 2b and 2b(ii) would not meet the RAO to:
• Minimize Infiltration: Minimize infiltration into
the landfill wastes and resulting contaminant
leaching to groundwater.
Alternatives 2b and 2b(ii) would collect a portion
of the landfill leachate after it is generated,
but would not prevent contaminant leaching to
groundwater by minimizing the infiltration of
precipitation into the landfill. Alternative 4c
would meet this RAO by minimizing infiltration
into the landfill, thereby effectively preventing
the generation of new leachate.
Alternative 2b would not meet the following RAO:
• Wetlands: Minimize loss of off-source wetlands,
and mitigate for any destruction of or damage to,
off-source wetlands from the remedial action.
Because Alternative 2b would require the dredging
and filling of more off-source wetlands than other
alternatives (in order to construct the treatment
berms), Alternative 2b would not likely meet this
RAO. There are other viable remedial
alternatives, including 4c, that would require the
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destruction of a lesser amount of off-source
wetlands.37
Because Alternatives 2b and 2b(ii) would not, or may
not, meet the RAOs discussed above. These alternatives
also may not meet the RAO for:
• Future Land Use: Provide final surface conditions
suitable for all season subsistence (i.e., hunting
and fishing), recreational, and light industrial
and commercial use) .
For additional information regarding the remedial
alternatives and the RAOs, see interim ROD Section 7.0
- Cleanup Objectives for the Interim Remedial Action,
and Section 9.0 - Summary of the Comparative Analysis
of Alternatives.
13.14 Comment: Commentor made several points comparing
Alternative 2b to Alternative 4c: [2] [17]
a. Alternative 2b provides better short-term
effectiveness and is approximately one-half the
cost of Alternative 4c.
Response: With regard to short-term effectiveness, EPA
notes that the potential effectiveness of Alternatives
2b and 2b(ii) is uncertain because their collection
systems are unproven. According to the results of
groundwater modeling conducted by the Respondents,
Alternative 2b and 2b(ii) allow the continued migration
of leachate into the Zone 2 aquifer. In the first ten"
years of operation, approximately 115 million gallons
of leachate would be discharged into the environment
(Colder, 1995b, Figure 4-2). This volume
optimistically assumes the trench system would continue
to function without clogging or other disruptions (EPA
believes clogging would likely occur). Moreover, the
volume of leachate discharging for Alternative 2b would
remain at approximately 8 million gallons per year38
in perpetuity, whereas leachate would virtually cease
after 12 years following the installation of the cap as
intended under Alternative 4c Colder, 1995b, Figure 4-
1). Clearly, Alternative 4c is more effective at
minimizing leachate migration in the long term, and the
NCP gives preference to long-term effectiveness over
37 (Alternative 2b(ii) may meet this RAO if the proposed holding tank is
not constructed in the off-source wetlands).
38 (Colder, 1995b, Figure 4-2)
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short-term effectiveness (Section 300.430 (f) (1) (ii) (E)
of the NCP). The effectiveness of Alternative 4c is
much more certain because low-permeability covers are a
proven standard landfill containment technology.
With regard to cost, EPA believes the relative costs of
Alternatives 2b, 2b(ii) and 4c are comparable. Given
the unproven nature and the uncertainties associated
with Alternatives 2b and 2b(ii), EPA believes the
Respondents have significantly underestimated the
potential costs of Alternatives 2b and 2b(ii).
Therefore, EPA has independently prepared cost
estimates for these alternatives based on more
realistic assumptions39. EPA's cost estimate for
Alternative 4c is also different than the Respondents'
estimate because EPA incorporated a contingency for
landfill gas treatment:
Respondents
Cost
Estimate
(in millions)
$13 .3
$11.8
$22.4
EPA
Cost
Estimate
(in millions)
$21.3
$20.8
$25.1
Alternative
2b - Leachate Collection with
Discharge to Treatment
Berm
2b(ii) - Leachate Collection
with Discharge to
POTW
4c - Geosynthetic Cover with
Passive Drainage
Using EPA's more realistic cost estimates for .
Alternatives 2b, 2b(ii), and 4c, it is apparent that
the costs of these alternatives are .relatively
comparable. The cost estimate for Alternative 4c is
less than 20% higher than the cost estimate .for the
Alternative 2b(ii), the least expensive of the three
alternatives.
b. Alternative 2b removes current leachate, while
Alternative 4c allows it to migrate to the
environment.
Response: After about the first 5 years of operation,
Alternative 4c allows less leachate per year to migrate
39
For information on why EPA believes these cost estimates are more
realistic, see interim ROD Section 11.3 - Cost Effectiveness.
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into Zone 2 (Colder, 1995b, Figure 4-1) . The NCP
states that long-term effectiveness is more important
than short-term effectiveness 40 C.F.R. 300. 430 (f) (1)
(ii) (E) . Over the long term, Alternative 4c much more
effectively minimizes leachate generation and migration
to a significantly greater extent than either 2b or
c. Alternative 2b results in less cumulative leachate
release for the next ten years than Alternative
4c.
Response: The cumulative leachate released into the
marine environment is initially (in the first 10 years
of operation) less under Alternatives 2b or 2b(ii) than
for Alternative 4c if the untried leachate collection
system works as well as the Respondents have predicted.
However, over the long term, the cumulative leachate
production is substantially greater for Alternatives 2b
and 2b(ii). According to estimates provided by the AOC
Respondents (Colder, 1995b) , the cumulative leachate
flow out of the landfill into the environment for the
leachate interception scenario will surpass the
cumulative leachate flow anticipated from an FML cover
in a period of 15 years. Furthermore, after 15 years
the annual rate of leachate discharge for Alternative
2b continues to remain at approximately 8 million
gallons per year. In contrast, the rate of leachate
discharge for Alternative 4c remains at nearly zero
after 15 years.
Also, EPA had a number of concerns regarding the use of
a POTW as part of Alternative 2b(ii), These concerns
include: (1) that the Alternative 2b(ii) system could
not be considered to be permanent because of its
relatively high O&M costs. The future viability of
this Alternative is vulnerable to unforeseen increases
in the price of POTW treatment and the cost of power to
run the collection system pumps; (2) the uncertainty
about whether the POTW treatment systems are capable of
effectively treating all the contaminants of concern in
the leachate; and (3) delays that could result from
administrative diff iculties~with obtaining permits and
access from construction of the proposed sewer line to
the POTW. Access would need to be obtained to
construct the pipe across at least one private property
parcel and the pipe would also need to cross the
Burlington Northern railroad tracks and a highway.
d. Alternative 2b provides treatment of landfill
constituents and does not impact wetlands;
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Alternative 4c does not treat landfill
constituents and will impact wetlands.
Response: Alternative 2b would require the destruction
of a significant amount of off-source wetlands to allow
construction of the treatment berms. Some incidental
impact to wetlands would be expected during the
construction of Alternative 4c. See also Response to
Comment 13.13.
Regarding treatment of landfill contaminants, EPA
questions whether the "treatment berms" proposed for
Alternative 2b would ""actually provide treatment of
landfill contaminants, or merely dilute them before
releasing them to the surrounding environment.
Alternative 2b(ii) would likely provide adequate
treatment of leachate. Although Alternative 4c is a
containment remedy that does not include an active
treatment system, some reduction of the toxicity of the
landfill waste under Alternative 4c would be expected
to occur as a result of biodegradation within landfill
waste. Biodegradation in landfills is a process by
which the solid^organic particles are solubilized and
converted to methane gas and carbon dioxide gas, which
are typically vented or flared. In addition,
Alternative 4-c is expected to eliminate leachate
production and contaminant loading to the off-source
areas. As such, it will effectively "contain" the
landfill wastes such that active treatment of the
wastes, is not required (or cost-effective).
"•— M~. . ~
13.15 Comment: Commentor asked whether incineration and
disposal of the on-site waste had been considered. [1]
Response:-. Based on EPA's experience with remediation
of landfills like the Tulalip Landfill, EPA has found
- that incineration as a remedy for source control of
contamination is impracticable and expensive. EPA has
found that containment remedies that effectively
prevent contact with landfill wastes and prevent
landfill contaminants from migrating to other areas are
less expensive, and are generally protective of human
health and the environment.
When EPA developed its presumptive remedy guidance for
municipal landfills, the Agency reviewed remedies
selected and implemented at 30 landfills around the
country. EPA found that incineration was routinely
eliminated from remedy selection because of cost. For
more information refer to EPA's presumptive remedy
guidances (EPA, 1990a, 1991, 1993a, and 1995a) and the
AR for the Tulalip Site.
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13.16 Comment: Commentor asked if Alternative 2b, the
treatment berm, were capable of achieving the degree of
treatment'that it projected, would it be considered an
acceptable alternative. [1]
Response: EPA believes that it would be difficult or
impossible to determine whether treatment was occurring
within the proposed treatment berms or whether the
leachate was simply being diluted. To determine
whether treatment was occurring, and to what degree, a
rather long-term comprehensive evaluation system would
be required. EPA would have to negotiate the terms,
conditions, and costs of the evaluation with the
parties responsible for remediation of the Site. EPA
expects that this would be a rather lengthy process.
EPA also anticipates that the evaluation process itself
would be of a long duration. The time that would be
required to negotiate, implement, monitor, and
interpret the result of such an evaluation system are a
concern to EPA because it may take years before EPA
could assess whether a reliable remedy had been
implemented at the Site. If the remedy failed, then an
impermeable cover, such as that described for
Alternative 4c, would have to be installed on the
landfill as a contingency. The interim remedy selected
by EPA in this interim ROD, which includes a cap, has a
long history of implementability and effectiveness --
neither of which has been demonstrated for the
treatment berm system. To date, the Respondents have
not submitted information which adequately supports the
implementability or effectiveness of the treatment berm
system. Implementability-and effectiveness.are two of
the nine criteria used by EPA to evaluate alternatives.
See Responses to Comments 13.13 and 13.14 for more
information about EPA's concerns regarding the
reliability and effectiveness of Alternative 2b.
13.17 Comment: Commentor suggested that additional fill
(demolition debris) could be imported to achieve the
desired slope and that limestone could be used to
adjust the leachate pH, which would reduce migration of
contaminants. [2]
Response: EPA may consider the use of demolition
debris as fill. However, the Agency has engineering
and toxicity concerns regarding the use of demolition
debris as fill at the Tulalip Site. Before accepting a
specific source of demolition debris, the Agency would
need information that.addresses EPA's specific
engineering and toxicity concerns. EPA would assess
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the information before agreeing to accept a specific
source of demolition debris. EPA would want to be sure
that the debris under consideration would not
contribute contamination to the Site.
Exposure of the landfill leachate to limestone would
likely increase the pH of the leachate, making it more
basic. As a result of raising the pH of the leachate,
one would expect metals to precipitate out of solution.
However, phenolic compounds, which have been detected
in landfill leachate, tend to become more soluble under
more basic conditions, so EPA believes it is unlikely
that limestone would provide effective treatment for
these types of contaminants. Limestone may not be
effective at treating other contaminants of concern,
such as pesticides or PCBs. Therefore, EPA does not
consider the use of limestone to be a viable long-term
treatment solution because it would not substantially
reduce migration of all leachate contaminants, even in
the short-term.
13.18 Comment: Commentor stated that the No Action
Alternative (1), and Alternatives 2, 2b, 3, 4a, and 4b
fail to meet the fundamental threshold requirements of
CERCLA. [2]
Response: Comment noted.
13.19 Comment: Commentor stated that many different caps are
currently available in addition to a FML cover. The
commentor suggested that a geosynthetic clay liner
(GCL) tolerates more damage, is more easily repaired,
is a natural product, and can cost less. [2]
Response: EPA agrees geosynthetic clay liners (GCLs)
can provide a viable alternative to FMLs.~~The interim
ROD provides for either a minimum 50 mil FML or a GCL
to be used as the low permeability layer in the Tulalip
cover design (see ROD Section 10.1.3 - Landfill Cover
Sysytem).
As pointed out by the commentor, GCLs have the capacity
to "self heal" if punctured. However, GCLs are
relatively new to the industry, and have not undergone
extensive testing as FML have. In addition, GCLs can
be slightly more expensive to install than FMLs
(approximately $0.50 per square foot for GCLs versus
approximately $0.40 per square foot for FMLs).
13.20 Comment: Commentor stated that there is not enough
information available to conclude that the long-term
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maintenance costs associated with impervious caps and
caps with flexible membrane liners are negligible. [2]
Response: Some of the flexible membrane liners (FMLs)
have been in use for two decades. This use has enabled
engineers to develop some conclusions regarding
maintenance requirements and costs. For the Tulalip
Landfill, anticipated operation and maintenance (O&M)
costs are estimated to be about $170,000 per year for
the selected alternative (Colder, 1995b.) When
evaluated over a 30-year period using present worth
value analysis and assuming a 5% discount rate, this
long-term maintenance cost amounts to $2.6 million.
This cost is comparatively lower than other
alternatives that were evaluated. For instance, the
EPA estimates that Alternative 2b would cost an
estimated $465,250 per year (with a present worth cost
of over $7 million in 30 years). Operation and
Maintenance costs for other alternatives provided in
the "Feasibility Study for Source Area Containment
(SAC-4)" (Colder, 1995a) and "Comparison of the
Leachate Collection and Treatment alternative (2b) with
the FML Cover Alternative (4c), Feasibility Study for
Source Area Containment (SAC-4)" (Colder, 1995b)
include the following:
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ALTERNATIVES
Alternative 2
.(Active Seep
Interception)
Alternative
2b(ii) Leachate
Collection and
Treatment
Alternative 3
(Seep and Zone 2
Controls)
Alternative 5
(Cover, Seep
Controls)
Alternative 6
(Cover, Seep,
Zone 2 Controls)
ANNUAL O&M
$220,000
$386,000
$620,000
$220,000
$280,000
PRESENT WORTH
O&M*
$3,400,000
5,900,000
$9,600,000
$3,400,000
$4,300,000
Calculated over 30 years with a 5% discount rate. O&M
costs for contingent landfill gas treatment are not included
because it is not certain that gas collection and treatment will
be necessary.40
The relatively lower O&M costs predicted for
Alternative 4c are largely due to the passive and self-
contained nature of engineered caps.
13-21 Comment: Commentor stated that EPA's preferred
Alternative 4c, the FML cover, is significantly more
expensive than and provides minimal additional benefit
over proposed Alternative 2b, Alternative Collection
and Treatment. [2]
Response: EPA disagrees. Alternative 4c meets the
nine NCP criteria and Alternatives 2b and 2b(ii) do
not. Alternative 4c is cost-effective and is not
significantly more expensive than Alternatives 2b and
2b(ii), see ROD Section 11.3 - Cost Effectiveness and
Response to Comments 13.14. Alternative 4c provides
significant additional benefits, see ROD Section 9 -
Summary of Comparative Analysis of Alternatives and
Response to Comments 13.13.
40 EPA notes that the need for continued operations and maintenance (O&M)
could exceed 30 years.
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13.22 Comment: Commentor expressed concern that the $25
million .clean-up cost may be grossly underestimated and
suggested -that the cost could grow as high as $90
million. [l]
Response: The commentor's suggestion that the cost of
the selected remedy could grow as high as $90 million
is highly unlikely. Both EPA and the Respondents have
independently performed cost estimates for the proposed
cap (Alternative 4c). EPA has determined that the $25
million cost estimate is within an acceptable range of
accuracy (i.e., +50 percent to -30 percent of the final
construction cost).
Review of the $25.1 million cost estimate shows that it
is very sensitive to changes in imported soil quantity.
Current grading plans presented in the "Revised
Feasibility Study for Source Area Containment (SAC-4)"
(Golder, 1995a) provided an estimate of 637,000 cubic
yards of imported fill at a total cost of $6.8 million
(import soil and top soil) plus an additional $1.2
million for regrading surface soil and waste. To
account for the commentor's estimated cost increase to
$90 million, the quantity or cost of fill and regrading
would likely need to increase nearly an order of
magnitude above current estimates. At this time, there
is no reason to believe this may occur.
Finally, comparison of actual costs for landfill cap
installation has shown that the $25.1 million cost
estimate is generally consistent on a per acre basis,
with other sites of similar magnitude 41.
13.23 Comment: Commentor suggested that Alternative 4c was
selected because it is the most protective and least
costly approach. Commentor also stated that the
proposed costs of the other alternatives may be
overstated, and costs of these alternatives could be
lowered with creative use of resources and engineering.
'[2]
Response: Comment noted.
13.24 Comment: Commentor stated that the Respondents have
evaluated Alternative 4c and agreed that it could cost
$25 million; however, the cost could increase to $40
41 See Responsiveness Summary Appendix A: EPA Review Comments on the
Comparison of the Leachate Collection and Treatment Alternative (2B) with the
FML Cover Alternative (4C), Specific Comment Number 17; also interim ROD
Section 11.3 - Cost Effectiveness.
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million depending on the amount of re-grading and
additional fill needed. [3]
Response: The cost estimates that are used in the
interim ROD are Feasibility Study (FS)-level cost
estimates. In general, EPA expects that actual remedy
costs will fall within a range of +50 percent to -30
percent of a FS cost estimate. The main purpose of FS
cost estimate is not to estimate the cost of each
remedial alternative with precision, but to allow a
comparison of the relative costs of the remedial
alternatives that are under consideration. Typically,
at Superfund Sites, a more accurate cost estimate for
the selected alternative would be prepared during the
Remedial Design phase of the process, which would
usually begin after a remedy is selected in a ROD. In
EPA's view, therefore, the commentor's statement that
the actual cost of implementing one of the alternatives
may significantly exceed the cost estimate is
premature.
Nevertheless, based on current information, EPA
believes it is unlikely that the actual cost of
implementing the selected remedy, Alternative 4c, would
grow to $40 million dollars. EPA considers this cost
figure to be extreme. Comparison of actual costs for
landfill cap installation has shown that the $25
million cost estimate is relatively consistent on a per
acre basis with other sites of similar size (see
Response to Comment 13.22). At this time, EPA believes
that the actual costs of Alternative 4c are equally
likely to be lower or higher than the $25 million cost
estimate. EPA notes that Dr". Greg Richardson, a
technical consultant who has worked for the Respondents
and The Tulalip .Tribes, stated at the second public
meeting that he believed the cost estimates for all of
the alternatives may be higher than the actual costs
will turn out to be (Northwest Court Reporters, 1995) .
See also ROD Section 11.3 - Cost-Effectiveness.
13.25 Comment: Commentor suggested that a protective and
effective remedy could be implemented (either a partial
cap or leachate collection and treatment alternative)
for $7.5 to 15 million, which is 30 to 60% less than
EPA's approach. [3]
Response: EPA estimates that a more realistic cost for
the Alternative 2b(ii) leachate collection and
treatment system is $21 million. The Alternative 4c
cap is expected to cost from about $22 million to $25
million, depending on whether gas treatment will be
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necessary. Given that the leachate collection system
has so many uncertainties regarding its
constructibility, long-term operation, and
effectiveness; from a cost standpoint alone, EPA
believes the Alternative 4c cap is a more cost
effective remedy.
13.26 Comment: The Tulalip Tribes plan to develop the
property, so a cap is redundant anyway because
buildings and asphalt can be good covers as long as
they are maintained. Why not make this the Tribe's
responsibility? [12]
Response: There are-*other parties in addition to The
Tulalip Tribes who are liable for cleanup costs at the
Site. These other parties include other parties that
operated the Site, transported waste to the Site, or
generated waste that was sent to the Site. The Tulalip
Section 17 Corporation42 is participating in the
allocation process to determine the fair share of
response costs to be allocated at the Site (see
Responses to Comments 5.1 and 5.2).
EPA selected an impermeable cap with a 2% grade to stop
the generation of leachate and to prevent pooling of
water on the surface. EPA selected the impermeable cap
because it satisfies, better than other alternatives,
the criteria by which EPA must evaluate response action
alternatives, including ARARs. One ARAR identified for
the Site is the Washington State MFS for landfill caps.
The MFS specify the design specifications for the
construction of caps. For the type of cap required for
the Tulalip Site, the placement of buildings and
asphalt on the Site as a cap would not meet the design
standards specifications in the MFS for the Site. For
more details see ROD Section 10.1 - Description of the
Selected Remedy.
13.27 Comment: EPA is ignoring its guidelines that match
cost-effective cleanups to the intended use of the
site. There was no mention of the intended use of the
site. [12]
Response: The commentor is incorrect. Future use of
the Site is summarized in the Proposed Plan (see pages
7 and 17), and is described in greater detail in the
document entitled "Big Flats Land Use Program" (Tulalip
42 The Tulalip Section 17 Corporation leased the Site to the Seattle
Disposal Company for landfill operations and was also involved in post-1980
capping operations at the Site.
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Tribes, 1994), which is available in the AR for the
interim ROD. Future use is also considered in the ROD
as one element of the "Community Acceptance" NCP
evaluation criterion (see ROD Section 9.0 - Summary of
the Comparative Analysis of Alternatives).
The interim ROD, Section 10.2 - Integrating the Interim
Action with Land Use Plans, states "The selected
interim remedy shall allow the on-source area of the
Site to be productively used by people, with some
restrictions necessary to prevent damage to the interim
remedy. To a reasonable and feasible extent, as
determined by EPA, the selected interim remedy shall be
designed and constructed to allow for the types of
future use activities described in the Big Flats Land
Use Program" (Tulalip Tribes, 1994) . The Tulalip
Tribes have identified recreational, light industrial,
and commercial uses for the source area of the Site,
and traditional hunting and fishing uses for the off-
source wetland areas.
EPA has concluded that the selected interim remedy
(Alternative 4c) is cost effective (see ROD Section
11.3 - Cost Effectiveness) and is compatible with these
future land use objectives. The selected interim
remedy is the least expensive alternative that is
protective of human health and the environment, and
meets all ARARs.
13.28 Comment: Commentor expressed concern that the landfill
site will be available for light industrial/commercial
use following the implementation of the remedy. The
commentor specifically wanted to know what effect on-
site development would have on the cap and what
landfill sites in the country have experienced similar
development following the installation of a landfill
containment system. [1]
Response: The selected interim remedy should allow the
on-source area of the Site to be productively used by
people, with some restrictions necessary to prevent
damage to the interim remedy. The selected interim
remedy shall be designed and constructed to be
compatible with the types of future use activities
described in the "Big Flats Land Use Program" (Tulalip
Tribes, 1994). This document is available for review
in the AR for the interim ROD.
Any activity on the cover beyond normal cover
maintenance activities shall be approved in advance by
EPA to help ensure that damage to the remedy will not
result. The degree of development to occur on the
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landfill will be dependent on the cap design and other
factors. It is feasible, and has been supported by the
Respondents, that development could include
construction of small structures for commercial or
light industrial use without detrimental impact to the
cap. Special provisions and restrictions, such as
utility and structural foundation placement, would most
likely be applicable based on the final cap design.
This level of development is consistent with the
intention of the Tulalip Tribes as described in the
"Big Flats Land Use Program" (Tulalip Tribes, 1994).
EPA43 plans to conduct a national study of remediated
landfills to determine potential uses for such sites:
however, to date the Agency has not routinely compiled
data about post-remedial uses of capped landfills. But
the Agency is aware that some capped landfills have
been used for recreational uses. Examples of some
landfill caps which have supported development include
a municipal landfill in Riverview, Michigan which
features downhill ski runs, a golf course, and several
single- and multiple-family homes; and a 50-acre
landfill near Cambridge, Massachusetts, which is to be
developed with bicycle paths, ball fields, tennis
courts, and a running track.
13.29 Comment: Commentor asked how long it will take before
light industrial development will be permitted to occur
at the site following the implementation of the
remedial action. [1]
Response: Development and beneficial use of some
portions of the site could begin immediately following
the cap construction with further development to occur
over a period of time. The Tulalip Tribes' Land Use
Program (Tulalip Tribes, 1994) provides a sequence of
expected uses on the landfill cover. According to the
Plan, light industrial use of the Site is expected to
begin 10 years after construction is complete.
13.30 Comment: The commentor believes that the remedial
investigation results support the need for remedial
action. The commentor supports EPA's selected interim
remedial action for the Site. The commentor concurs
with the observations in the Proposed Plan regarding
the importance of the Snohomish River Delta as an
important fish and wildlife habitat. Specifically, the
commentor states that the delta areas at risk are .
43 Personal communication between Lynda Priddy, Environmental Scientist,
EPA, Region 10 with Ken Skahn, Office of Emergency and Remedial Response, EPA
Headquarters on 2 February 1996.
-------
critical areas for important ecological functions and
are critical habitat to animals. [16]
Response: Comment noted.
13.31 Comment: The commentor stated that the remedial action
must include and integrate effective fish and wildlife
habitat restoration. None of the alternatives
identified in the Proposed Plan integrate cleanup with
habitat restoration which should be vital to selecting
the remedy. The commentor concluded that integrating
the remedy and restoration is less costly than treating
the issues separately. An integrated strategy
maximizes environmental benefits. [11]
Response: The Proposed Plan for Interim Remedial
Action at the Tulalip Landfill Superfund Site only
addresses remediation of the on-source area of the
Site. The on-source area is the area of the landfill
itself including the perimeter berms. EPA is presently
evaluating data to determine whether and to what extent
the off-source area (the surrounding wetlands) have
been adversely affected by the landfill and whether
additional remediation of the wetlands will be
necessary.
The proposed remedy reflects EPA's determination that
it is not possible to achieve complete fish and
wildlife habitat restoration at this Site through the
remedy selected by EPA. The natural resou'rce trustees
have been satisfied with EPA's level of coordination
and consultation with them in reaching- this decision.
Although EPA's proposed remedy does not restore lost or
damaged resources, the natural resource trustees for
the Site have identified a project to acquire and
protect from development property in the vicinity of
the landfill which represents the equivalent resources
that have been damaged or lost due to the release of
hazardous substances at the landfill. The natural
resource trustees for the Site will work with EPA to
determine whether additional restoration activities
will be required to restore lost or damaged off-site
natural resources.
EPA offered the de minimis parties an opportunity to
settle their natural resource damages liability as part
of the de minimis settlement for the remediation of the
Tulalip Landfill Site. As of February 16, 1996,
approximately 80% of the de minimis parties have signed
up for the natural resource damages settlement,
contributing approximately $660,000.
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13.32 Comment: Commentor stated that approximately 17 inches
of precipitation may run off of the cap, if installed.
In light of this, the commentor asked if anyone had
evaluated the effects of such conditions on juvenile
salmon utilizing wetlands associated with the landfill.
[2]
Response: EPA requested that the Respondents conduct
such an evaluation in the feasibility study for source
area containment. The Respondents replied that such an
.evaluation should be done during remedial design and
that it was premature to evaluate this type of effect
of a remedy during the RI/FS. Design changes can be
made during remedial design to address potential
problems.
13.33 Comment: Commentor stated that the proposed remedy has
the potential to significantly impact the wetlands and
estuarine tidal channels surrounding the landfill,
resulting in a violation of EPA's "no net loss of
wetland" policy. Commentor stated that EPA has not
adequately evaluated the potential impacts of the
proposed remedy because it has neither required, nor
allowed the types of studies needed to evaluate these
impacts. [2] [3]
Response: Although implementation of the selected
remedy, Alternative 4c, will change the hydraulics of
the surrounding wetlands (for example, the selected
alternative is expected to result in the elimination of
landfill leachate seeping through the perimeter berm
onto the surrounding wetlands within two years), EPA
believes that the benefits of greatly reducing
contaminant migration from the landfill wdj.1 likely
offset any potential harm to the off-source wetlands
due to altered hydraulics. If the off-source wetlands
are harmed as a result of the selected interim remedial
action:,s>*4:he damaged wetlands would need to be restored,
mitigated, or replaced.
Wetlands systems are extremely complex. In EPA's view,
it would be very difficult to design a study that could
assess potential changes in the wetlands that would be
expected to result from hydraulic changes due to
implementation of the selected remedial action.
.Conducting such a study would likely be expensive, time
intensive, and the results may be of questionable
value.
EPA has determined that the most appropriate way to
remediate the Site is in phases. Thus, the source area
will be remediated and, as stated above, the remedial
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measures taken on the source area are expected to
result in a benefit to the surrounding wetlands through
a reduction of leachate flow to the surrounding
wetlands. The second phase of the remediation includes
completing the comprehensive baseline risk assessment
for the off-source area to determine the extent of
contamination and appropriate response measures for the
off-source area. Additionally, the natural resource
trustees for the Site have identified a project to
acquire and protect from development property in the
vicinity of the landfill which represents the
equivalent resources that have been damaged or lost due
to the release of hazardous substances at -the landfill.
The natural resource trustees for the Site will work
with EPA to determine whether additional restoration
activities will be required to restore lost or damaged
off-site natural resources. All of these measures
combined are likely to result in a determination and
implementation of the appropriate response measures to
be taken on the surrounding wetlands.
13.34 Comment: The Commentor expressed the concern that none
of the proposed remedial alternatives will be effective
in the wetland areas of the site. Consequently, they
request that the selected remedial alternative
eliminate any potential threats to human and
environmental health. [4]
Response: EPA believes that the selected remedy will
effectively halt the generation of leachate after the
cap has been installed. The volume of leachate already
in the landfill will decrease and within about 2 years
cease discharging from the landfill through the
perimeter berm into the wetland. Therefore, future
contamination of the wetland area is expected to stop.
To assess the present condition of the wetland or off-
source area, EPA will be conducting a comprehensive
baseline risk assessment on the wetland area around the
source-area. Based on the results of that
comprehensive baseline risk assessment, EPA will
determine whether additional remedial work is needed to
protect/restore the wetland. EPA will request public
comment on the Proposed Plan for the off-source area.
The Proposed Plan will specify remedial action, if any,
necessary for the off-source or wetland area
surrounding the Landfill.
13.35 Comment: Commentor asked if any of the existing
landfill is considered wetlands and if so, if the
landfill closure will require a permit from the Army
Corps of Engineers. [1]
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Response: An evaluation of the landfill surface and
surrounding areas is being conducted by EPA to
determine 'the approximate size and type of any wetland
areas. EPA expects that this habitat assessment will
be completed in the spring of 1996. Pursuant to CERCLA
Section 121, EPA is not required to obtain a permit for
remedial activities at a Superfund site.
Wetlands species have begun to establish themselves on
parts of the landfill surface. For purposes of the
selected interim remedy, the source area on the
landfill will fall under section 402 of the CWA, which
is administered by EPA, rather than Section 404, which
is administered by the Corps. See Section 11.2 -
Compliance with ARARs, for more information. See
Response to Comment 13.31.
13.36 Comment: The Tulalip site is in an estuarine
environment which should not only call for but require
a broader range of alternatives than are applicable to
typical upland landfills on which the presumptive
remedy is based. [3]
Response: At some point in the RI/FS process, EPA has
given full consideration to every interim remedial
containment alternative that has been suggested by the
Respondents. EPA delayed issuing the Proposed Plan in
order to fully evaluate Alternative 2b, which the
Respondents submitted to EPA after the Source Area
Containment FS was completed. EPA also solicited
additional input during the public comment period on
the Proposed Plan.
EPA notes that the "treatment berm" concept proposed as
part of Alternative 2b is not a technology that is at
all suitable to a "typical upland landfill." The
treatment berm concept, as proposed by the Respondents
depends on the presence of tidal waters to mix with
leachate within the berms.
13.37 Comment: Commentor asked how long a monitoring program
would be conducted before the remedy was considered
successful. [4]
Response: An EPA-approved, post-construction
monitoring plan will be prepared for the Site. The
monitoring plan require data which will be used to
evaluate the effectiveness of the remedy and to assess
whether the remedy remains protective of human health
and the environment. After the first two years of
post-construction monitoring are complete, EPA may re-
evaluate the frequency of collection of post-monitoring
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data and of quarterly monitoring reports. See also ROD
Section 10.1.5 - Post-Construction Care for additional
information.
13.38 Comment: Commentor asked if a monitoring program would
continue after the off-source containment area remedy
was established. [4]
Response: Monitoring may be required after a ROD is
issued for the off-source remedy. At this time it is
unknown what monitoring needs there may be for the off-
source areas. EPA expects to establish monitoring
requirements for the off-source area in the final ROD.
13.39 Comment: Commentor asked who will be responsible for
maintenance repair work (e.g., the gas collection
treatment system) of the landfill. [4]
Response: It is not known at this time who will be
responsible for operations and maintenance (O&M) of the
selected interim remedy. This would depend on the
results of future negotiations EPA expects to conduct
with the PRPs, the Tulalip Tribes, and other parties,
regarding construction of the selected interim remedy
and other issues. O&M responsibilities would likely be
part of these negotiations.
13.40 Comment: Commentor asked what actions EPA will take to
resolve further contaminant migration issues if the
remedy fails to meet established success criteria. [4]
Response: See Response to Comment 13.37. If, as a
result of site monitoring, EPA concludes that the
interim remedial action is unsuccessful at containing
the landfill wastes, additional containment actions,
such as construction of a perimeter leachate collection
system, may be necessary.
13.41 Comment: Commentor asked how the condensate associated
with the gas collection treatment system operations
would be handled. [4]
Response: Details regarding the handling of landfill
gas collection system condensate are normally
determined during remedial design.
13.42 Comment: Commentor asked whether the cap would require
additional maintenance if differential settlement
occurs at the Site and whether the $25 million cost
estimate takes this into consideration. [1]
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Response: The O&M at the Tulalip Landfill site would
include repairing any damage that may occur due to
differential settlement. Anticipated expenditures for
this type of O&M activities have been factored into the
cap's cost estimate.
13.43 Comment: Since EPA only required leachate controls
when the Agency approved the reopening of the Tulalip
Site, then EPA should only require these same controls
when they are closing the site. [12]
Response: EPA evaluated the use of several leachate
collection systems in its evaluation of remedial
alternatives in the Tulalip Landfill Feasibility Study.
In EPA's evaluation of remedial alternatives in the FS,
the Agency concluded that leachate collection systems
alone as a remedial solution would not be protective of
human health and the environment or meet ARARs
identified for the site. The Agency has serious
concerns about construction and operation of certain
types of leachate collection systems.
Regulatory controls dictated by regulations in the past
(such as controls that may have been state-of-the-art
or regulatory requirements at the time the landfill was
open) that are now known to be ineffective in
protecting human health and the environment are not
appropriate remedies. EPA must make its decisions
consistent with good science and existing regulations
which are based on knowledge and technology which have
advanced since the early 1980's. EPA screened out for
consideration remedial alternatives clearly would not
meet the remedial response objectives identified for
the Site and which did not meet the other criteria EPA
must consider in selecting a remedy. Given that EPA
had concluded that leachate systems alone could not
address human health and environmental concerns
identified at the Site, EPA selected another remedial
alternative that would address the migration of
contaminated leachate from the site and exposure to
landfill contents.
t •
Leachate seep control alternatives 2, 2b, and 2b(ii)
would allow continued migration of contaminated Zone 2
groundwater to the sloughs, and would not prevent
contact with landfill contaminants. These alternatives
may not meet the RAO to prevent inhalation and release
of landfill gas that exceeds ambient air standards.
The seep control alternatives may not meet surface
water ARARs where Zone 2 groundwater discharges to the
sloughs or, in the case of Alternative 2b, at the face
of the treatment berm if the berm is not effective.
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Alternatives 2, 2b, and 2b(ii) do not comply with MFS
because they do not include a landfill cover.
Alternative 2b may not meet Section 404(b) of the Clean
Water Act because it requires dredging and filling of
off-source wetlands, and there are protective, ARAR-
compliant alternatives (i.e., the selected interim
remedy) that would require the destruction of
significantly less off-source wetlands. The leachate
collection system alternatives 2b and 2b(ii) carry
significant risk of failure, including the potential
for clogging and other problems, and therefore may not
be protective in the long term. For more information
on seep control versus landfill cover alternatives see
Section 9.0--Summary of the Comparative Analysis of
Alternatives, in the ROD for interim remedial action.
See also Responses to Comments 2.12.1 and 2.12.2.
13.44 Comment: Commentor wanted to know why an interim
remedy was warranted for the site given the letter
drafted by Bill Glasser, RPM, U.S. EPA, in 1992,
stating that there were no imminent or acute threats to
human health or.the environment posed by the site.
Commentor wanted to know what had changed at the site
between the time the letter was drafted and now. [2]
Response: See Response to Comment 2.8.2. The document
the commentor is apparently referring to is not a
letter (Glasser, 1992). It is a "removal assessment."
13.45 Comment: Commentor stated that the observation of
ponded water on the landfill at various times of the
year indicates that the cover presently out there is
not highly permeable, as suggested by EPA. [2]
Response: Ponded water on the surface of the landfill
may be caused by the Zone 1 water table intersecting
the landfill surface in some areas and by perched water
(leachate or rainwater) over poorly draining surface
soils in other areas. For example, leachate seep SP-01
in the eastern portion of the landfill is a location
where the Zone 1 water table intersects the landfill
surface, resulting in a leachate seep and an area of
ponded leachate alongside the landfill access road. In
other areas, there may be some areas of less permeable
surface soils. However, water levels in the refuse
layer vary by as much as 3 feet with the highest water
levels measured during the rainy winter months and the
lowest water levels measured during the summer. The
seasonal variation in water levels clearly shows that
rainfall infiltrating through the relatively porous
surface soil is the primary source of groundwater
recharge to the refuse layer. This observation is
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further supported by the relative absence of surface
water runoff pathways from the landfill surface to the
surrounding wetlands.
EPA notes that permeability is relative. For example,
sand is highly permeable relative to clay, but gravel
is highly permeable relative to sand.
13.46 Comment: Commentor stated that it has not currently
been shown that migration of leachate into groundwater
and into surface water poses an unacceptable risk.
Therefore, the need to actually decrease migration of
leachate into groundwater has not been fully
established. [2]
Response: The number and magnitude of comparison
number exceedances by chemicals in leachate, as
identified in the Final Tulalip Landfill Risk
Assessment for Interim Remedial Action (Weston, 1995b)
is sufficient justification to state that leachate
poses a potential threat to human health and the
environment. This potential threat justifies the need
for action. This action includes containment,
including control of the leachate. See Response to
Comment 2.10.1. •
13.47 Comment: Commentor stated that EPA shouldn't rush
ahead with a presumptive remedy but should instead take
plenty of time and thoroughly explore all of the
available alternatives. [2]
Response: At some time during the RI/FS-process, EPA
has carefully evaluated all of the interim remedy
options that the Respondents have proposed. EPA has
evaluated 11 interim remedial action alternatives in
the interim ROD, including a No Action alternative,
alternatives that do and do not include a landfill
cover, and alternatives that are proven and unproven
technologies for containing and treating landfill
wastes. At every Superfund Site, EPA must weigh the
benefits of obtaining additional data or conducting
additional evaluations against the benefits of
expeditiously proceeding with selection and
implementation of a response action, if appropriate, to
address potential threats to human health and the
environment posed by a Site. The NCP states that EPA
should consider this weighing process with a "bias for
action" (see Response to Comment 2.5.4). In the case
of Tulalip Landfill, at this time, EPA believes that a
sufficient number and range of interim containment
alternatives have been evaluated, that there is
sufficient information regarding potential risks to
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conclude that the Site represents .a potential threat to
human health and the environment, and that, based on
the evaluation of alternatives required by the NCP,
Alternative 4c is the most appropriate alternative to
implement as an early/interim remedial action.
13.4.8 Comment: Commentor argued that the zero-sloped trench
throughout the landfill will immediately fail and that
such an alternative will be impossible to "back-flush".
[2]
Response: EPA shares the commentor's concerns with
Alternative 2b and 2b(ii). EPA anticipates that
clogging of the leachate collection system pipes and
drainage media with biological solids and inorganic
precipitates would be a severe and costly maintenance
problem that would be further compounded by the
proposed zero-slope trench design.
In addition, EPA notes that clogging of the pipe and
drainage media may be difficult to detect. To ensure
proper functioning, such a collection system would
require periodic maintenance to prevent an unscheduled
or unintended interruption. Furthermore, replacement
of the drainage system, including piping, drainage
media, and pumps would likely be required during the
course of its operation.
13.49 Comment: Commentor stated that the presumptive remedy
should not be, by default, an impervious cap.
Commentor suggested that the Tulalip Landfill should
not be considered a typical landfill in Western
Washington given the physical features of the area and
its location in an estuary. [2]
Response: The presumptive remedy for the Tulalip
Landfill is containment, not an impervious cap. The
Respondents evaluated many containment alternatives in
the feasibility study for source area containment
(Colder, 1995a) including various combinations of
permeable soil covers, relatively impermeable caps,
leachate interception, leachate containment by vertical
barriers, and groundwater containment by vertical
barriers. EPA has thoroughly considered and evaluated
all of the alternatives proposed by the Respondents and
has solicited public comment during the 80-day public
comment period on the Proposed Plan.
13.50 Comment: Commentor asked if lateral or tidally
influenced flow of groundwater was present through on-
site waste, and if so, how the current recommended
action would prevent horizontal contaminated
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groundwater flow from influencing zone 1 and 2
groundwater. [4]
Response: See Response to Comment 9.1
13.51 Comment: Commentor asked what criteria would be used
to evaluate the source area containment remedy. [4]
Response: The nine evaluation criteria contained in
the National Contingency Plan (NCP) have been used to
evaluate the source area containment remedy
alternatives (see ROD Section 9 - Summary of
Comparative Analysis of Alternatives).
13.52 Comment: Commentor asked what the areal extent of
surface soil contamination is, and if the contamination
associated with the surface soil is the vehicle driving
the preferred capping remedy. [1]
Response: The extent of surface soil contamination, as
it relates to exceedances of human health and
ecological-protective criteria, is identified in the
Final Tulalip Landfill Risk Assessment for Interim
Remedial Action (Weston, 1995b).
Surface soil contamination is not the major reason for
taking remedial action at the Site. The need for
interim remedial action is driven by numerous
exceedances of health-based comparison numbers and
biological effects-based comparison numbers in landfill
leachate discharging to the wetlands, groundwater
discharging to surface water, wetland soil around the
perimeter of the landfill, and surface water and
sediment in the tidal channels surrounding the
— landfill. However, the primary reason for the remedial
action at the Site is the exceedances of effects-based
comparison numbers in the leachate.
13.53 Comment: Commentor asked if EPA has evaluated trends
in contaminant concentrations at other un-capped
landfills with similar leachate problems. [13—
Response: The Agency has not studied trends in
contaminant concentrations in leachate from either
covered or uncovered landfills44.
44 Personal communication between Lynda Priddy, Environmental Scientist,
EPA, Region 10 and Ken Skahn (contact in EPA Headquarters for Superfund
municipal landfill presumptive remedies), Environmental Engineer, Office of
Emergency and Remedial Response, Environmental Protection Agency on 2 February
1996 .
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13.54 Comment: Commentor suggested that the proposed Interim
Action is not consistent with EPA's regulatory
guidance.. The commentor explained that EPA defines the
reasons for taking an interim action as "the need to
take quick action to protect human health and the
environment from an imminent threat in the short-term
while a final remediation solution is being developed."
It is the opinion of the commentor that because no
"imminent hazard" is clearly defined and agreed upon at
this site that the use of an interim remedy is a
misapplication. [2]
Response: EPA's "Guidance on Preparing Superfund
Decision Documents". (OSWER Directive 9355.3-02, July
1989, page 9-11), states that EPA may determine that it
is appropriate to implement an interim action at a
site. The guidance states that interim actions "which
may be removal or remedial actions, can be taken to
respond to an immediate site threat or to take
advantage of an opportunity to significantly reduce
risk quickly."
EPA's designation of the remedy selected in the ROD as
an interim action is appropriate and consistent with
EPA guidance. Data gathered at the Site during the
RI/FS confirm that an immediate threat to human health
and environment exists at the landfill. Based on the
results of the_RI and the Risk Assessment, EPA has
concluded that the Site may pose an imminent and
substantial endangerment to human health and the
environment. This finding suggests that it is
appropriate for EPA to take action in the form of an
interim action to contain discharges at the Site in a
prompt and effective manner. An emergency situation
requiring immediate response is not necessary in order
for EPA to implement an interim remedy. EPA has other
mechanisms, such as removal actions, which may be used
in emergency situations. -EPA believes that rt- is
appropriate to institute an interim remedy at the
source area of the landfill rather than to allow the
leachate to continue to be generated and released into
the environment unabated until a final remedy which
addresses site-wide environmental problems can be
selected and implemented.
EPA's Guidance further states that "interim actions are
limited in scope and are followed by other operable
units that complete the steps to provide definitive
protection of human health and the environment for the
long-term." Consistent with this statement in the
Guidance, the PRPs, pursuant to an AOC, have conducted
studies of the source area of the landfill and the
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information gathered has provided an adequate basis on
which to evaluate risks and alternatives for
remediation for the source area. A complete evaluation
of the off-source area of the Site has not been
completed and it is premature to determine the
appropriate response action to be taken for the off-
source area. Thus, EPA determined, given the
documented existence of hazardous substances on the
source area which pose a risk to human health and the
environment, that it would be prudent and appropriate
to address those threats through the use of an interim
remedy and to address off-source threats through a
final remedy.
13.55 Comment: Commentor indicated that a cap is standard
practice for a landfill. [2]
Response: Comment noted.
13.56 Comment: Commentor stated that a zero-infiltration
cover over the landfill is not required, and that a
certain amount of infiltration can be tolerated while
still eliminating seeps. [2]
Response: There is no such thing as a "zero-
infiltration cover," because all cover systems develop
leaks over time. However, groundwater modelling
conducted by the Respondents during the FS suggests
that the perimeter berm leachate seeps may be
eliminated if infiltration into the landfill can be
reduced from its current level of 17.1 inches per year
to approximately 0.07 inches per year (Colder, 1995c,
Appendix A, page A-2, Section A.3 and page A-4, Section
A.5). This infiltration reduction is achievable only
with a cap with a low permeability layer consisting of
an FML, or with a cap that has a low permeability layer
such as a GCL with a maximum permeability of 1 x 10"9
centimeters per secondT Alternative 4a, for example,
which is a soil cover, would not achieve the
required infiltration reductions.
13.57 Comment: Commentor stated that in rare instances the
treatment of leachate can be cost-effective. However,
as a rule, preventing and minimizing leachate is far
less costly than treating leachate. [2]
Response: In general, EPA agrees that, in most cases,
it is more cost effective to prevent and minimize
leachate than to treat it. This is the main reason
that remedies for landfills like the Tulalip Landfill
are almost always containment remedies that include a
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low permeability cover. Operation and maintenance
(O&M) costs for collection and treatment of leachate at
the Tulalip Landfill site are considerably higher than
O&M costs associated with preventing formation of the
leachate. When considering long term operation, the
relatively higher cumulative O&M costs for leachate
treatment tend to offset any savings gained from the
relatively lower capital costs associated with
construction of leachate treatment systems.
13.58 Comment: Commentor stated that EPA Region 10 has
determined that the surface of the landfill is
contaminated based on data from one leachate seep on
the surface of the landfill. Commentor further stated
that this area represents less than one-quarter of one
acre of the 143 acre landfill surface, or less than
0.2% of the surface area. Commentor argued that this
data is insufficient to justify a capping remedy. [3]
Response: EPA based the decision for interim remedial
action and selected a containment remedy, including a
cover, for the Tulalip Site based on the Agency's
concern for contaminant migration via leachate from the
on-source area of the Site to the off-source area of
the Site. The reason the surface of a landfill is
covered is primarily based on the need to eliminate
leachate generation over the long-term in a reliable
and effective manner, not to prevent exposure of people
and environmental receptors to surface or subsurface
soils. See Response to Comment 11.23.
The EPA presumptive remedy guidance "Presumptive Remedy
for CERCLA Municipal Landfill Sites," page 5 (EPA,
1993), states "(s)treamlining the risk assessment of
the source area eliminates the need for sampling and
analysis to support the calculation of current or
potential future risk associated with direct contact."
The Agency has found in its experience with landfill
remediation that surface and subsurface soil data play
a small role in the data used to select a remedy.
Therefore, for the Tulalip Site, the Agency did not
focus on gathering subsurface soil data or additional
surface soil data beyond what was already available.
EPA disagrees that EPA "determined that the surface of
the landfill is contaminated based on one leachate seep
on the surface of the landfill." See Response to
Comments 2.9.2, 2.9.3 and 11.7 for a discussion of
EPA's evaluation' of the landfill surface.
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14.0 MICROBIOLOGICAL STUDIES
14.1 Comment: •Commentor stated that the microorganism
research at the site does not support the conclusion of
human health risks from microorganisms leaching from
the landfill. For example, the commentor claims the
microbiological data presented in Appendix C of the
Risk Assessment document do not suggest that
microorganisms pose risks at the landfill. [3]
Response: EPA presented microbial data from samples
taken over a period of twenty years at and around the
Tulalip Site. Based on that data, EPA concluded in the
Streamlined Risk Assessment for the Site that
"microbial contamination at the site may pose a
potential health risk to humans." However, in EPA's
microbial analysis, the Agency did not attempt to
"conclusively" link the microbial contamination in off-
source matrices to the landfill. EPA has not, nor will
the Agency claim, that the microbial data represents a
"microbial risk assessment." At most, the Agency
observes that some risk may occur from exposure to
matrices that are contaminated. It is not within the
scope of the RI/FS investigation and review at the
Tulalip site to assess the degree of risk that may
result from exposure to microbial organisms at the
Tulalip site. There are no pathogen risk-based
concentrations on which to perform such an analysis.
EPA's purpose in mentioning a potential risk from
exposure to these microbial organisms is to note that
data is available to suggest a potential risk.
However, EPA believes that with the installation of a
cover over the landfill that over time the microbial
population of concern will decrease. The population is
expected to decrease as the leachate seeps dry up, thus
eliminating the transport of microorganisms from the
landfill through the leachate seeps into the
environment surrounding the landfill.
14.2 Comment: Commentor expressed the opinion that the data
presented in a memo prepared by Mr. Dean Boening of IGF
(3/17/95) lacked any clear description of a sampling
plan, including sampling plan objectives; sampling
locations; and methods of sample collection, handling,
transport, and laboratory analysis. The commentor also
did not understand the rationale for selecting the
three indicator groups and five species of bacteria
included in the study. The commentor suggested that
the chosen organisms were useful in determining the
presence of human fecal coliform contamination and the
potential for transmission of enteric pathogens. [3]
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Response: Microbiological investigations followed the
Quality Assurance Project Plan for the Site. Sampling
locations were determined according to locales selected
from earlier investigations that produced elevated
levels of microbial contaminants. Leachate samples
were collected from characterized leachate seeps.
Sample collection, handling, transport, and laboratory
analysis was conducted according to:
APHA. 1989. Standard Methods for the Examination
of Water and Wastewatert 18th ed. American Public
Health Association., Washington, B.C.
Food & Drug Administration Bacteriological Manual,
5th ed. 1984. American Public Health Association.,
Washington, D.C.
E.P.A. 1978. Microbiological Methods for
Monitoring the Environment, Water and Wastes. EPA-
600/8-78-017.
The microbial data was collected over a period of 20
years. Therefore, much of the data conforms with the
standards and protocols normally associated with
collection of the microbial samples. The initial site
investigations (in the 1970s) were conducted according
to NPDES regulations, which regulated these bacterial
indicators. These early investigations preceded the
Superfund program. Currently, local, state and federal
agencies conducting microbiological monitoring programs
also commonly analyze for the indicators (total
coliform (TC), fecal coliform (FC) and fecal
streptococci (FSc)) identified in the Streamlined Risk
Assessment for the Tulalip site. Evaluated populations
of TC, FC and FSc are considered to be indicative of
the presence of pathogenic bacteria. Also, PCs were
analyzed for because published standards are available
for PCs, making "exceedances" easier to regulate.
Infectious microorganisms originating from hospitals
(E. coli, C. perfingens, S. aureus and P. aeuruginosa)
which could survive at a landfill would mainly be
bacteria associated with eye, ear, nose, throat,
genitourinary, respiratory, and staph infections.
These five bacterial species were of interest because
they are common etiologic agents in these infectious
episodes.
The above commentor also had the following comments:
a. Several potential significant sources of
microorganisms, including antibiotic resistant
organisms, are known to exist in the area,
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including sewage treatment plant wastewaters,
dairy farms, septic tanks, wildlife, and urban
runoff.
Response: In general, effluent from these practices
can be sources of antibiotic resistant bacteria.
However, EPA is not aware of any peer-reviewed
literature that substantiates the claim that these
bacteria are "known to exist in the area" surrounding
the landfill.
b. Background and off-site concentrations of
microorganisms were similar to on-site
concentrations.
Response: The size of a microbial population is not
necessarily predictive of the risk of infection from
that organism. For example, exposure to a small
population of metabolically dormant organisms during
the winter months may be just as infective as an
exposure to a larger, metabolically active population
of the same organism during the spring and summer
months. Because microbial agents may replicate in the
field, the concept of concentration (e.g., chemical) as
an indicator of toxicity is not necessarily considered
to be an indicator of infectivity for microbial agents.
Opportunistic pathogens may be ubiquitous in an area,
but that does not make them less pathogenic.
Also, comparison of on-site population numbers to
background or off-site populations numbers (in addition
to reasons explained above) may not be indicative of a
risk because even an ubiquitous population requires a
host to be infective and these organisms are very
species-specific. In other words, even if the
microbial population at the landfill was less than
background, if a host was present at the landfill then
infection is possible through direct and indirect
contact.
Investigations from 1970 to 1992 show that on-site
microbial populations at the Tulalip Site were higher
than background or off-site populations. However,
sampling in 1992 and 1993 indicated that on-site
populations are similar to background and off-site
populations. This decrease over the last couple of
years does not decrease EPA's concern about the
infective potential of these organisms for reasons
stated below.
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c. A consistent trend of decreasing microorganism
concentrations were measured in the area over
time.
Response: Generally, the concentration of microbial
populations at most upland landfills decrease over
time. For example, facultative aerobic bacteria
persist up to 10 years in a standard upland landfill.
However, conditions at the Tulalip Site (abundant
nutrients and oxygen), provides a conductive milieu for
most aerobic/facultative populations to persist far
beyond this 10 year period. Therefore, EPA believes
that the Tulalip Site may be a longer-term source of
bacterial indicators than would be generally expected.
d. Standard protocols for testing for antibiotic
resistance were not used.
Response: Standard protocols (Kirby-Bauer disk agar
diffusion procedure) were followed. This is the
protocol used worldwide by clinical and applied
microbiologists. The citations are as follows:
Federal Register. 1972. Rules and regulations.
Antibiotic susceptibility disks. 37 Fed. Reg.
20525-20529 (Erratum: 38;2756/ 1973) .
National Committee for Clinical Laboratory
Standards. 1992. Fourth informational
supplement: M 100-S4. Performance standards for
antimicrobial susceptibility testing. NCCLS,
Villanova, PA.
e. Antibiotic resistance of background and off-site
microorganism samples were similar to on-site
samples.
Response: EPA agrees. However, the assumption that
this statement is based on (resistance patterns of
background organisms are "innocuous") may not be true.
In other words, these antibiotic resistant strains may
or may not have originated from the landfill and
migrated into nearby sediments.
Resistance traits are carried on and transferred via
extrachromosomal plasmids. These transfers occur among
a variety of bacteria, including the fecal coliform
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family45. Exactly how long an environmental bacterium
will retain these plasmids is unknown but some
authorities have observed that bacteria possessing
multiple resistance factors are more hardy and less
subject to environmental stress than native strains
lacking resistance factor plasmids.46
f. The indicators and specific species evaluated are
ubiquitous in the environment .
Response: See Response to Comment 14. 2 (b) above.
g. The presence of antibiotic resistance in any of
the organisms does not necessarily qualify them as
pathogens .
Response: The expression of antibiotic resistance is
unrelated to the classification of a bacterium as a
pathogen. The pathogens that have been a concern at
the landfill are "opportunistic." That is, these
ubiquitous organisms can take advantage of any
opportunity to invade a human host either directly or
indirectly.
14.3 Comment: The commentor stated that the microbiological
study did not evaluate viruses or other agents that
could impact human health. Commentor asked if there is
concern that such agents may potentially be present.
Response: EPA did not evaluate the possibility that
viruses or "other agents" were present at the Tulalip
Site. Animal viruses do not "grow" in the environment
and would not be expected to survive in the long-term
outside of a host, especially while exposed to ambient
environmental conditions. EPA assumes that what the
commentor means by "other agents" is protozoan agents.
EPA's purpose was not to perform a full-fledged
microbial risk assessment but to summarize microbial
data that was primarily already available from previous
investigations conducted over the last twenty years.
EPA is not claiming that viruses or "other agents"
"5 Kelch, W.J. and J.S. Lee, 1978. Antibiotic Resistance Patterns of
Gram-negative Bacteria Isolated from Environmental Sources. Appl.
Environmental. Microbiol. 36:450-456.
46 Grabow, W.O.K., I.G. Meddendorff and O.W. Prozesky. 1973. Survival in
Maturation Ponds Containing Coliform Bacteria with Transferable Drug
Resistance. Wat. Res. 7:1589-1597.
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(apart from the microbiological data) may pose a
significant risk, or any risk for that matter, at the
Tulalip Site. Similarly, EPA only concluded from the
bacterial data that a risk to human health may exist.
14.4 Comment: Commentor stated that the microbiological
data (Appendix C in the Risk Assessment document) are
not consistent with the summary presented in Section
2.4 of the document. [3]
Response: Tables 1 through 9 of Appendix C were
present in the Draft Final Streamlined Risk Assessment
(Weston, 1995a). These Tables were inadvertently left
out of the Final Streamlined Risk Assessment (Weston
1995a). No changes were made in the Tables and the
information in the Tables was present in the AR (e.g.,
Draft Final Streamlined Risk Assessment) during the
comment period on the Proposed Plan.
14.5 Comment: Commentor stated that the microorganism
concentrations reported in the corrected "most probable
number" data tables dated January 31, 1994, and
presented at the end of Appendix C of the Streamlined
Risk Assessment do not correspond to the data presented
in EPA's memo dated March 17, 1995. [3]
Response: The data tables from January 31> 1994 and
March 17, 1995 do correspond. The January 31, 1994
data tables do not conflict with the data in Tables 1
through 9, but instead augments it. The January 31,
1994 data was inadvertently left out of the data
summary presented in Tables 1-9. —
15.0 FUTURE SITE STUDIES
15.1 Comment: Commentor asked if other studies-are being
performed on biota of different trophic levels in the
future. If so, the commentor asked if the study would
be similar to the study of PCBs and eagles in the Hood
Canal area. [4]
Response: EPA is currently working on a comprehensive
baseline risk assessment that will include an
assessment of the potential impacts of site
contaminants on upper trophic levels. This study will
be significantly different than the study of PCBs and
eagles in the Hood Canal area. The comprehensive
baseline risk assessment will use Site data to evaluate
potential risk to upper trophic levels using the off-
source areas of the Site, such as the Northern Harrier
(Marsh Hawk) and the Great Blue Heron, from exposure to
D-226
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Site contaminants, which include but are not limited to
PCBs. The Hood Canal study, on the other hand, covered
a larger geographical area (the Hood Canal area), but
focused more narrowly on a specific species (eagles)
and specific contaminants (PCBs).
16.0 MISCELLANEOUS COMMENTS
16.1 Comment: The commentor believes "...the EPA staff, in
the science and engineering disciplines, is unqualified
to render the decisions that they have put forth." The
commentor believes there is a huge disparity between
the EPA's staff credentials and those of the PRPs.
Consequently, the commentor states that EPA should
withdraw the Proposed Plan because: (1) EPA has not
completed the baseline risk assessment; (2) EPA staff
is not qualified to select the remedial action; (3) the
Proposed Plan ignores the language in HR 2099 which is
part of EPA's continued funding in HJR 108; (4) the
Proposed Plan does not take into account EPA's
-•*- administrative reforms published on October 2, 1995;
(5) the remedy is not consistent with other remedies
selected at NPL landfills in Region 10 or the Agency's
presumptive remedy AR; and (6) EPA has not responded to
the University of Washington's appeal to remove the
Site from the NPL. [5]
Response: EPA is confident in the qualifications of
its staff and in the individual staff members'
competency in conducting the duties which EPA is
mandated to perform. Referrals to responses to the
above comments, are as follows:
(1) EPA has not completed the baseline risk assessment:
ASee Responses to Comments 2.1, 2.2, and 2.3;
(2) EPA staff is not qualified to select the remedial
action: See Response to Comment 16.1;
(3) the Proposed Plan ignores the language in HR 2099
which is part of EPA's continued funding in HJR 108:
See Responses to Comments 2.6 and 2.17;
(4) the Proposed Plan does not take into account EPA's
administrative reforms published on October 2, 1995:
See Response to Comment 2.6;
(5) the remedy is not consistent with other remedies
selected at NPL landfills in Region 10 or the Agency's
presumptive remedy AR: See Responses to Comments 2.4
and 2.14; and
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(6) EPA has not responded to the University of
Washington's appeal to remove the Site from the NPL:
See Response to Comment 4.1.
D-22.8
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ATTACHMENT A
DE-MINIMIS SETTLEMENT ISSUE
AND OTHER LIABILITY COMMENTS
EPA received comments regarding liability issues,
primarily about the de minimis settlement, during the 'public
comment period for the Proposed Plan. The public comment
period was for the Proposed Plan, EPA's evaluation and
selection of a remedy for the Tulalip Landfill. EPA has
responded to those comments in the Responsiveness Summary.
However, comments about liability issues that were given at
the public meeting are addressed, separately, in this
attachment because they do not directly relate to the
selected remedy for the Site. EPA will respond directly, in
writing, to commentors who submitted de minimis liability
comments in writing to EPA during the public comment period
and were not given at the public meeting.
1.0 Comment: Commentor asked if all de-minimis parties
have been contacted, including public bodies, and if
they were on both a list and an invoice list. [2]
Response: EPA used several sources to prepare a master
list of approximately 6,500 parties associated with the
Tulalip Landfill. The sources included Marine Disposal
Company logbooks, as well as information supplied by
Rubatino Refuse Company and Waste Management, Inc. EPA
i_s_ offering de minimis settlements to appropriate
parties on the master list, including public bodies,
who contributed between 0.01 and 0.6 percent of the
total waste at the site. The settlement offers are
being conducted in three rounds.
Those parties with waste volumes below 0.01% of the
total waste volume at the Site are not being offered
settlements. These parties have been determined by EPA
to be de micromis parties, and consistent with EPA
guidances and policy, are not being asked to contribute
a portion of the response costs incurred at the Site.
In addition to the master list, EPA has in its
possession approximately 28,000 ledger cards supplied
by the Seattle Disposal Company. To date, EPA has
reviewed this ledger card information for those parties
already on the master list and identified as eligible
for a de minimis settlement. EPA is initiating a
comprehensive review of these ledger cards in order to
determine if additional parties, beyond those already
identified, are eligible for a de minimis settlement.
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2.0 Comment: Commentor asked if.there was a mechanism in
place to return money to the people on the de minimis
list if the Tulalip site was taken off of the NPL list.
[2]
Response: No. Even in the unlikely event that the
Tulalip site is taken off of the NPL, EPA retains its
authority to take enforcement action to compel cleanup
at the site.
3.0 Comment: Commentor asked if the post-1980 users are
being asked to contribute to the settlement. [2]
Response: The Tulalip Section 17 Corporation47, U.S.
Navy, and other post-1980 users of the site are
currently participating in a formal allocation process.
The purpose of this process is to determine fair and
equitable cleanup cost shares for these and other
parties.
4.0 Comment: Commentor asked what action the EPA would
take if the de minimis invoice parties did not pay
their bill within the 30-day period. [2]
Response: The settlement to de minimis parties is
offered in the form of an administrative order on
consent (AOC). The AOC provides for each settling
party to make a cash payment to the Unites States for a
proportionate share of past and future response costs
at the site. Payments will be due only after the AOC
becomes effective. After receiving .binding signature
pages from the settling parties, EPA will sign the AOC
and it will be made available for public comment.
Following the public comment period, the AOC will
become effective after the settlement is approved by
the United States Department of Justice. EPA will then
send notice to each settling party that the AOC is
effective. _ Payments by the settling parties will be
due 30 days after receiving notice that the AOC is
effective.
EPA will not determine in advance the action it will
take to enforce the terms of the AOC against a party
who signs the settlement but fails to make the required
payment. By signing and returning the AOC signature
page to EPA, Settling Parties agree to be bound to the
terms of the settlement, which requires each party to
47\ The Tulalip Section 17 Corporation leased the Site to Seattle Disposal
Company for landfill operations and was also involved in post-1980 capping
operations at the Site.
D-230
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submit specified payments within 30 days after receipt
of notice of the effective date of AOC. Parties who do
not do suqh, will be considered in violation of the
AOC, and subject to enforcement proceedings. As stated
in Paragraph 23 of the AOC, pursuant to Section 122(1)
of CERCLA, a Settling Party who fails or refuses to
comply with a term or condition of the AOC is subject
to a civil penalty of up to $25,000 per day of such
failure or refusal. In addition, a party who fails to
make the. payments will not gain the benefits of a
covenant not to sue from the United States, and will
not enjoy contribution protections provided settlors
under CERCLA.
5.0 Comment: Commentor, identifying himself as a former
customer of Rubatino Refuse, asked how it was that EPA
determined 516 tons of scrap wood materials were hauled
from his property and disposed of at the landfill.
Based on the content of the public meeting's
proceedings, the commentor expressed that he was not
prepared to enter into a de minimis settlement that the
EPA requested. The commentor is not convinced the
liability to those participating will be eliminated
because leachate may continue to migrate from the site
following the implementation of the remedy. [1]
Response: The total "tonnage attributed to each
generator customer of Rubatino Refuse Removal, Inc.
(RRR) was based on documents prepared by RRR at the
time of landfill operations, including daily trip
reports, and on sworn testimony of RRR drivers. Where
driver information showed a consistent waste generating
activity for a party during the period 1975-1979 - such
was the case for WW Wells Millwork - EPA calculated the
total volumetric contributions of each generator
customer for that period using the average monthly
volume of documented waste activity during the 1978
period as the basis. The waste volume was then
converted to tonnage using a conversion factor of 283
pounds/cubic yard.
The public meeting that the commentor attended was for
the purpose of discussing the Proposed Plan for the
Tulalip Landfill Superfund Site, not the details of the
de minimis settlement. EPA held separate informational
meetings with de minimis parties, and made all
information upon which party-specific volume decisions
were made available to the de minimis parties for
review and comment prior to responding to the
settlement offer.
D-231
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The commentor is correct that response actions at the
site may be ongoing for some time. However, the de
minimis settlement is an opportunity for eligible
parties to settle their potential liability for
response costs with regard to the site. As noted in
the Response to Comment 4.0 above, the settlement
provides important benefits to settling parties,
including a covenant not to sue and contribution
protection, in exchange for paying a share of past and
future response costs at the site. Taken together, a
covenant not to sue, contribution protection, and other
de minimis settlement terms provide a high level of
certainty that settling parties will be protected from
future legal actions related to the matters addressed
in the settlement.
6.0 Comment: Commentor asked why the pre-1980 users of the
landfill are being asked to pay to clean up the site.
[1]
Response: Pre-1980 users of the landfill are being
asked to pay to clean up the Site because EPA has
evidence that the waste they brought to the Site
contained hazardous substances. The pre-1980 users of
the landfill fall within the definition of liable
parties under section 107 of CERCLA, 42 USC 9607, and
are therefore responsible for the payment of response
costs.
EPA is issuing de minimis settlement offers to parties
who contributed between 0.01 and 0.6 percent of the
total waste at the site. Parties with waste
contributions above 0.6 percent are not eligible for a
de minimis settlement offer, but have been or will be
invited to participate in an allocation process. There
are thousands of parties who contributed less than 0.01
percent. EPA has no plans to offer settlements to
these very small contributors"" at this time because of
the substantial administrative costs that would be
incurred relative to the very minor contributions
likely to be recovered.
7.0 Comment: Commentor wanted to know what the impact of
the baseline risk assessment would be on the current
time table for PRPs who have and have yet to receive
de minimis settlement offers. The commentor also asked
about the cost basis for parties who are potentially
liable who have not yet received de minimis offers and
whether those that have will -have their offers re-
evaluated. [2]
D-232
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Response: The comprehensive Baseline Risk Assessment
will have no effect on the time table for the de
minimis settlements. The two processes are proceeding
independently. In addition, EPA does not expect the
cost basis for the de minimis settlements to change.
This is an early de minimis settlement and therefore
total site costs are estimated as accurately as
possible based on current information. Early
settlement offers give parties an opportunity to "cash
out" early in the process so as to avoid further
involvement at the site. The actual total site costs
may turn out to be lower or higher than the amount
estimated for purposes of the settlement offer. Thus,
though settling de minimis parties risk that the costs
will be lower than anticipated by EPA, EPA risks that
the costs will be higher than anticipated and EPA will
not be able to seek those extra costs from the parties
who have already settled.
8.0 Comment: Commentor suggested EPA use the concept of
periodic payments to settle the PRP's liability rather
than a lump sum. Commentor stated that this payment
philosophy, as described by the commentor, is modeled
from personal injury tort litigation. The commentor
explained that an advantage of this method is that the
defendant can typically settle the case for less money
and the plaintiff can typically receive more money.
The commentor also suggested that favorable tax
consequences often result for both parties. The
commentor explained that the defendant receives the
current tax deduction for their expenses for the
settlement case. In addition, the defendant is able to
settle the case at a lower cost because the settlement
is spread out over time and it is,'in effect,
annuitized. Consequently, the commentor explained that
the plaintiff faces no tax consequences. [2]
Response: EPA appreciates the commentors suggestion.
D-233
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ATTACHMENT B
FIGURES
4-1
AND
4-2
D-234
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140
120 '
100 -
e
a
•2
x
_3
LL
0.00 2.00 '1.00 6.00
0.00 10.00 12.00
Time (yr)
•Alt. 4c
'Alt. 28
14.00 16.00 18.00 20.00
FIGURE 4-1
PREDICTED FLUX OUT OF
LANDFILL INTO ZONE 2
TULALIP LANDFILLAVA
-------
2001Z
0!
3
1
u.
0)
•a
J2
"5
£
3
U
10.00 ' 12.00 14.00 16.00 18.00
20E+6
OOOE+0
FIGURE 4-2
CUMULATIVE LEACHATE FLOW OUT OF
LANDFILL INTO ENVIRONMENT
TULALIP LANDRLL/WA
JSS\953122S\63S31 10/23/95
Colder Associates
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ATTACHMENT C
LIST OF REFERENCES
This List of References is meant to assist the reader in
locating documents cited in this Responsiveness Summary and is
not meant to serve as an exclusive listing of all documents EPA
relied on in determining the need for remedial action or
selecting the remedy for the Tulalip Landfill Site.
Boening, D. 1995. Memorandum to Jerry Muth, U.S. EPA,
entitled "Microbiological Narrative of Contamination at the
Tulalip Site and Associated Human and/or Ecological Risks.
March 17, 1995. Prepared for the U.S. Environmental
Protection Agency.
Boening, D. 1994. Memorandum to Jerry Muth, U.S. EPA,
regarding corrected MPN values. January 31, 1994. Prepared
for the U.S. Environmental Protection Agency.
Ecology and Environment (E&E). 1988. Site Inspection Report
for Tulalip Landfill. July 1988.
Findley, C. 1995a. Letter to R. Truitt, Piper & Marbury,
regarding dispute resolution final determinations on
Respondent's request for work plan modifications at the
Tulalip Landfill. 18 October 1995. U.S. Environmental
Protection Agency.
Findley, C. 1995b. Letter to R. Truitt, Piper & Marbury,
regarding dispute resolution final determinations on five
technical issues at the Tulalip Landfill raised by the
Respondent's. 18 October 1995. U.S. Environmental
Protection Agency.
Flynn, J. 1995. Letter to E. Winiecki, EPA, regarding
responses to EPA comments on the Draft Remedial
Investigation Report. 12 April 1995. Harding Lawson
Associates.
Gearheard, M. 1995a. Letter to R. Truitt, Piper & Marbury,
regarding dispute resolution on respondents' request for
work plan modifications for Tulalip Landfill. 4 August
1995. U.S. Environmental Protection Agency.
D-235
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Gearheard, M. 1995b. Letter to R. Truitt, Piper & Marbury,
regarding dispute resolution on five technical issues at the
Tulalip Landfill raised by the Respondent's. 4 August 1995.
U.S. Environmental Protection Agency.
Glasser, W. 22 April 1992. Removal Assessment at NPL
Sites. U.S. Environmental Protection Agency.
Colder Associates. 1995a. Feasibility Study for Source
Area Containment (SAC-4), Tulalip Landfill Remedial
Investigation and Feasibility Study. May 1995.
Colder Associates. 1995b. Comparison of the Leachate
Collection and Treatment Alternative (2B) with the FML Cover
Alternative (4C). Feasibility Study for Source Area
Containment (SAC-4). October 1995.
Colder Associates. 1995c. Development and Evaluation of
the Treatment Berm Alternative, Feasibility Study for Source
Area containment (SAC-4). June 30, 1995.
Harding Lawson Associates (HLA). 1995. Remedial
Investigation Report, Tulalip Landfill, Snohomish County,
Washington. May 1995.
Harding Lawson Associates (HLA). 1994. Geotechnical
Investigation and Landfill Gas Evaluation Report, Tulalip
Landfill, Snohomish County, Washington. July 1994.
McAllister, R. 1995. Letter to R. Truitt, Piper & Marbury,
explaining that EPA does not agree with Respondents'
arguments regarding the Draft Risk Assessment. 26 July
1995. U.S. Environmental Protection Agency.
McKenna, E. 1995. Letter to file regarding application of
presumptive remedy at Tulalip Landfill. 4 August 1995.
U.S. Environmental Protection Agency.
Mitsch, W.J. and J.G. Gosselink. 1993. Wetlands,, second
edition. Van Nostrand Reinhold Publishing, New York, NY.
National Oceanic and Atmospheric Administration (NOAA).
1991. Preliminary Natural Resource Survey, Tulalip
Landfill, Marysville, WA.
Northwest Court Reporters. 1995. Transcript of Facilitated
Public Meeting on the Tulalip Landfill, Seattle, Washington.
October 3, 1995.
Puget Sound Estuary Program (PSEP). 1988. The Apparent
Effects Threshold Approach. Briefing Report to the EPA
Science Advisory Board. Puget Sound Estuary Program.
' D-236
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Richardson G. N. 1995. Letter to B. O'Neal, EMCON
Northwest, regarding peer review of Tulalip Landfill
Proposed Plan for Interim Action. 17 August 1995. G. N.
Richardson & Associates.
Truitt, W. R. 1995. Attachment to Letter to E. Winiecki,
EPA, regarding request for RI/FS Work Plan modifications.
23 February 1995. Piper & Marbury.
Tulalip Tribes of Washington. 1994. Big Flats Land Use
Program. July 10, 1994.
U.S. Environmental Protection Agency (EPA). 1995a.
Memorandum from James E. Costello and George B. Wyeth
entitled "Presumptive Remedies and NCP Compliance". June
14, 1995.
U.S. Environmental Protection Agency (EPA). 1995b. Support
Document for the Revised National Priorities List Final Rule
- April 1995. Office of Solid Waste and Emergency Response.
NPL-FR-U14-4-2.
U.S. Environmental Protection Agency (EPA). 1995c.
Memorandum from Elliott P. Laws, Assistant Administrator,
entitled "Land Use in the CERCLA Remedy Selection Process."
OSWER Directive 9355.07-04. May 25, 1995.
U.S. Environmental Protection Agency (EPA). 1994. EPA
Region III Risk-Based Concentration Table. Fourth Quarter,
1994.
U.S. Environmental Protection Agency (EPA). 1993a.
Presumptive Remedy for CERCLA Municipal Landfill Sites.
Directive No. 9355.0-49FS. September 1993.
U.S. Environmental Protection Agency (EPA). 1993b.
Wildlife Exposure Factors Handbook, volumes I and II.
U.S. Environmental Protection Agency (EPA). 1991.
Conducting Remedial Investigations/Feasibility Studies for
CERCLA Municipal Landfill Sites. OSWER Directive 9355.3-11.
February 1991.
U.S. Environmental Protection Agency (EPA). 1990a.
Streamlining the RI/FS for CERCLA Municipal Landfill Sites.
OSWER Directive No. 9355.3-11FS. September 1990.
U.S. Environmental Protection Agency (EPA). 1990b. A Guide
to Selecting Superfund Remedial Actions. OSWER Directive
9355.0-27FS. April 1990.
D-237
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U.S. Environmental Protection Agency (EPA). 1989a. Risk
Assessment Guidance for Superfund. Vol. I. Human Health
Evaluation Manual.
U.S. Environmental Protection Agency (EPA). 1989b. Risk
Assessment Guidance for Superfund. Vol. II. Environmental
Evaluation Manual.
Washington State Department of Ecology (Ecology). 1995.
Model Toxics Control Act (MTCA) Cleanup Levels and Risk
Calculations (CLARCII) Update. January 1995.
Washington State Department of Ecology (Ecology). 1994.
Natural Background Soil Metals Concentrations in Washington
State. Publication No. 94-115. October 1994.
Washington State Department of Ecology (Ecology). 1993.
Sediment Management Standards. Washington Administration
Code 173-204.
Washington State Department of Ecology (Ecology). 1992.
Water Quality Standards for Surface Waters of the State of
Washington. Washington Administration Code, Chapter 173-
201A.
Washington State Department of Ecology (Ecology). The Model
Toxics Control Act (MTCA) Cleanup Regulation, Chapter 173-
340 WAC. February 1991.
Washington State Department of Ecology (Ecology). Solid
Waste Landfill Design Manual. Prepared by Parametrix. June
1987.
Washington State Department of Ecology (Ecology). 1985.
Minimum Functional Standards. Washington Administrative
Code, Chapter 173-304. October 1985.
Weston, Inc. 1995a. .Draft Final Risk Assessment for the
Tulalip Landfill Interim—Containment Remedy. June. 1995.
Prepared for U.S. Environmental Protection Agency.
Weston, Inc. 1995b. Final Tulalip Landfill Risk Assessment
for Interim Remedial Action. August 1995. Prepared for
U.S. Environmental Protection Agency.
Weston, Inc. 1992. Draft Preliminary Site Assessment of
the Tulalip Landfill. Letter from R. Henry (WESTON REAC) to
D. Charters (EPA). September 8, 1992.
D-238
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Winiecki, E. 1995a. Letter and attachments to R. Truitt,
Piper & Marbury, to make objections and invoke SAC-4 dispute
resolution. 17 February 1995. U.S. Environmental
Protection Agency.
Winiecki, E. 1995b. Letter to J. Flynn, Harding Lawson
Associates, regarding comments on Draft Remedial
Investigation Report. 16 March 1995. U.S. Environmental
Protection Agency.
Winiecki, E. 1995c. Letter to Larry Adams, Monsanto,
transmitting the Final Risk Assessment for Interim
Containment Remedy. 4 August 1995. U.S. Environmental
Protection Agency.
Winiecki, E. 1995d. Memorandum to The File by Eric
Winiecki regarding EPA comments on the Treatment Berm
Alternative including Development and Evaluation of the
Treatment Berm Alternative, dated June 30, 1995. 4 August
1995.
Winiecki, E. 1995e. Letter to Larry Adams, Monsanto,
regarding response to the Respondents' request for RI/FS
Work Plan modifications at the Tulalip Landfill, dated
February 17, 1995.
Woods, B. 1996. Memorandum to L. Priddy, regarding
comments by Parametrix on the data quality of the 1988 data
for Tulalip landfill. 31 January 1996. U.S. Environmental
Protection Agency.
The Administrative Record is available for public review at
the United States Environmental Protection Agency, Records
Center, 1200 6th Avenue, Seattle, Washington and at the
Marysville Public library in Marysville, Washington. To request
a copy of a document in the Administrative Record, call the EPA
Records Center at (206) 553-4494.
D-239
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Interim Remedial Action ROD
APPENDIX E
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APPENDIX E
EPA REVIEW COMMENTS
ON THE
COMPARISON OF THE LEACHATE COLLECTION AND THE TREATMENT
• ALTERNATIVE (2B) WITH THE FML COVER ALTERNATIVE (4C) ,
DATED OCTOBER 24, 1995
During the public comment period for the Proposed Plan, the
Respondents submitted new information to EPA regarding a
variation of Alternative 2b - Leachate Seep Collection with
Treatment Berms. This document, dated October 24, 1995, is
entitled "Comparison of the Leachate Collection and Treatment
Alternative (2b) with the FML Cover Alternative (4c) " (Colder,
1995b). The document provides detailed information on sending
collected leachate to an off-Site sewage treatment plant, or
Publicly Owned Treatment Works (POTW), instead of through
treatment berms. EPA has evaluated both of these variations in
the interim ROD, differentiating them as follows:
• Alternative 2b - Leachate Seep Collection with Treatment
Berms; and
• Alternative 2b(ii) - Leachate Seep Collection with Discharge
to POTW.
Alternatives 2b and 2b(ii) use the same basic leachate
collection system. The main difference between the two
alternatives is that one would send the collected leachate to
treatment berms, the other to a POTW. According to the proposal,
under Alternative 2b(ii) the leachate would be sent to either
the Marysville or Everett POTW where it would be treated along
with other effluent streams received by the POTW.
This Appendix presents EPA* s technical comments on the
October 24, 1995 submittal. For EPA's evaluation^of Alternative
2b(ii) using the NCP criteria,refer to interim ROET'Section 9.0 -
Summary of the Comparative Analysis of Alternatives, and interim
ROD Appendix A.
GENERAL COMMENTS
1. -Alternative 2b and Alternative 2b(ii) share the same basic
leachate collection system. Many comments EPA has made
previously about the collection system proposed for
Alternative 2b also apply to the Alternative 2b(ii).
However, many of EPA's concerns were not addressed in the
October 24, 1995 submission (Colder, 1995b). EPA expressed
the following concerns about alternative 2b:
E-l
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• difficulty of constructing trenches for the leachate
collection system through landfill waste;
• difficulty of installing level collection pipes in
several feet of standing water at the bottom of the
trenches;
• difficulty in accessing the collection pipes for
repairs;
• clogging of collection pipes over time;
• relatively high operation and maintenance (O&M) costs;
and
• lack of adequate data or technical analyses to support
the Respondents' claims that the proposed collection
system would eliminate leachate seepage.
These concerns are also applicable to 2b(ii) because of the
similarities between the two systems. The October 24, 1995
submittal could have, but did not, attempt to address these
concerns relative to 2b(ii). In EP,A's August 3, 1995,
letter to the Respondents (Eric Winiecki, EPA, to Anthony
Burgess, Colder Associates) transmitting EPA's review of the
"Development and Evaluation of the Treatment Berm
Alternative (Colder, 1995c), which describe Alternative 2b,
EPA^stated on page 7: .
The SAC reports submitted to date, including the
subject report, have not provided adequate
justification to support the statement that all
leachate seepage would be eliminated by the treatment
berm or similar leachate interception alternative.
To date, this justification has not been provided to EPA.
There are numerous uncertainties associated with the
leachate collection and treatment alternative. Adequate
trench design and spacing is heavily dependent on hydraulic
properties of the waste. There is reference to aquifer -
testing to try to confirm these properties. However, EPA
notes that these are landfill waste materials, which are
expected to be .less homogenous than soil media or sediments.
The boring and testing programs for defining the hydraulic
properties to allow a reasonable confidence level with the
design of the spacing of the trenches is likely to be
extensive. The trench spacing provided in the Respondents'
submittals is highly conceptual, a best guess, based on very
limited data in Zone 1. The trench depth, as proposed,
ranges from 12-25 feet with a minimum width of 3 feet,
depending on waste consistency. The volume of waste to be
E-2
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excavated is consequently also very speculative, as it is
dependent on all the above. EPA questions the viability of
returning all of excavated waste to the same trenches as
proposed, versus the potential need for other, additional
disposal options. This has not been sufficiently evaluated.
3 . The document inappropriately downplayed the potential for
•plugging and its impact within the leachate collection
system. The cost estimate for the leachate collection and
treatment alternative should have specifically identified,
in addition to contingency for unexpected events, corrective
actions to be followed (e.g., digging up and replacement of
portions of the interceptor trench, etc.) to address
plugging within the interceptor trenches, including
operation and maintenance (O&M) funds to implement these
corrective actions.
4 . The advantage of using low permeability landfill covers to
reduce infiltration into landfills and consequently reduce
leachate production is that it is a proven technology with
respect to materials, installation, and the ability to
operate and maintain the system. Construction and Quality
Assurance (CQA) procedures for installation-and repair of
FML landfill cover systems are well established, including
ASTM standards and EPA guidances. In contrast, the
Respondents who proposed the 2b(ii) approach did not submit
information that supports 2b(ii) as a technology tEat is
proven for the use and circumstances for which it has been
proposed.
5. Based on evaluations performed by the Respondents, the
selected alternative (4c) is expected to result in lower
rates of leachate migration to Zone 2 than Alternatives 2b
or 2b(ii) . The lower rate of" leachate migration to Zone 2
expected from Alternative 4c has a relatively high degree of
certainty because low permeability landfill covers are a •
proven technology with relatively predictable results. The
leachate migration rates associated with Alternatives 2b and
2b(ii), on the other hand, are relatively uncertain because
Collection systems of this type are unproven. Consequently,
the expected rate of leachate migration that may result from
implementation of Alternates 2b and 2b(ii) is subject to
numerous uncertainties (see the following comments) .
Because the estimated lower leachate migration rates
associated with Alternative 4c are considered to be more
certain estimates, the fact that these numbers are lower
must be viewed as very significant. Alternative 4c is
expected to meet all RAOs without the need for additional
contingencies. During the detailed design phase,
Alternative 4c can be optimized to minimize waste excavation
and soil importation.
E-3
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6. It is likely that the cost estimate for the leachate
collection and treatment alternative 2b(ii) is significantly
underestimated due to the critical inputs (i.e., trench'
spacing, etc.) into the analysis being really more
appropriately characterized as best guesses versus
conservative or non-conservative assumptions. A more
realistic cost estimate for Alternative 2b(ii) has been
prepared by EPA (see Table 1 in this Appendix).
7. Some information was provided for the Everett POTW that was
not provided for the Marysville POTW. Information should
have been provided for both POTWs since both were proposed
as potential recipients of landfill leachate.
8. Current landfill gas emission of methane at the Tulalip
Landfill is estimated to be 228,000,000 cubic feet per year
(HLA, 1994b). This quantity would likely increase as the
water levels in the landfill decrease thereby enabling
additional refuse degradation. Furthermore, constituents of
landfill gas can cause offensive odors or threaten human
health. PSAPCA regulations provide requirements for
allowable gas emission rates, air emissions detrimental to
persons or property, and odor and nuisance controls
measures. Landfill gases generated under the scenario
depicted by Alternative 2b or 2b(ii) would be released to
the atmosphere since these alternatives possesses no
provisions for containment of such gases.
'. .*Eor alternative 4c, a gas collection system consisting of a
piping and trench network would be installed be.neath the low
permeability cover. The recovered gases could then be
treated by incineration or flares as necessary.
SPECIFIC COMMENTS
1. Page 3, Section 2.1: It is unclear from the description of
the biopolymer slurry technique how the drainage media (both
drain piping and filter pack) would be installed, and what
impact residue from the slurry would have on the interceptor
trench's performance. Supporting documentation and
references for the biopolymer slurry technique should have
been provided.
2. Page 4, Section 2.1.1: The reference to treatment berms in
the first sentence appears to be incorrect, since
Alternative 2b(ii) does not include treatment berms.
3. Page 6, Section 2.2: a) Copies of the chemical and flow
data presented to personnel at the Everett and Marysville
POTWs should have been provided in an appendix to the
report.
E-4
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b) A discussion of the compliance status for each of the
POTWs should have been provided. CERCLA wastewaters are
prohibited from being sent to a facility that is not in
compliance with-its permits.
c) The mechanisms (e.g., monitoring and reporting
requirements) that each POTW would employ to ensure that the
.wastestream will be acceptable to its treatment system over
the long term should have been provided.
d) The hydraulic capacity of each POTW is discussed.
However, discussion of other technical issues should also
have been provided, such as the organic loading capacity of
each POTWs treatment system; the suitability of each POTW's
treatment systems for the wastestream; and whether each
treatment system would be expected to treat the leachate
constituents, and to what degree.
4. Page 7, Section 2.3: This section should have included
descriptions of the monitoring measures required to maintain
the system. As a minimum, these measures should have
included float controls, redundant processes for mechanical
equipment, and performance monitoring of the trenches and
piping network. Monitoring controls for this alternative
"~ are likely to be more numerous, substantial, and costly than
for Alternative 4c.
5. Page 8, Section 2.5.1: a) Clogging of the interceptor
trenches from siltation or biofouling remains an important
concern for this alternative since detection of a localized
blockage would be difficult. The appropriate selection of
aggregate and/or geotextile would be difficult due to the
variability of soil and refuse across the site. Moreover,
correct placement of these materials may prove complicated,
particularly when using ^-slurry to maintain trench
integrity. These issues should have been discussed in more
detail.
b) The comparison of a trench pipe system to a screen in a
well is not a valid comparison. A drainage trench such as
those proposed for Alternative 2b(ii) cannot be developed in
a similar manner to a well screen because a trench has
different fundamental characteristics than a well, including
horizontal position, long lengths, and inability to create
the forces necessary to move the fine material near the
screen.
6. Page 9, Section 2.5.2: More information should have been
provided regarding the potential need for pretreatment of
the leachate prior to discharge to each POTW. According to
the Department of Ecology, the results of dilution effects
testing and a stream loading study of. the Snohomish River is
E-5
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anticipated to result in modifications to the Everett POTW's
NPDES permit limitations. Both the Everett POTW and Ecology
have indicated the potential for ammonia to be included in
future effluent limits.48 This could result in the need
for the leachate to be pretreated prior to discharge to a
POTW.
7. Page 10, Section 3.1: a. The statement that all RAOs are
achieved by this alternative [2b(ii)] is incorrect. The RAO
for landfill gas requires prevention inhalation and releases
of landfill gas exceeding ambient levels or PSAPCA
regulation standards. Leachate collection and treatment
Alternative 2b(ii) will not likely meet this RAO, and may
:"**"" not meet many others (see Response to Comment 13.13.)
b. The document should have specified whether the
pipeline(s) between the landfill and the POTW would be
dedicated to the Tulalip Landfill leachate, or if they would
be linked to other sanitary or storm sewer systems, nor did
it include a discussion of appropriate containment measures
for the wastestream.
8. Page 10, Section 3.2: This document has not provided
adequate justification to support the statement that all
leachate seepage would be eliminated by the proposed
leachate collection system. This concern remains
unaddressed.
9. Page 11, Section 3.3: This section should have indicated
whether the POTWs were willing to accept the leachate for
the entire duration of the discharge (potentially
indefinitely), and should have provided supporting
documentation of this from the POTWs.
10. Page 12, Section 3.3: The claim that the interception
system for Alternative 2b(ii) "provides greater certainty
that this RAO will be achieved than the FML cover
alternative (4c)" is inconsistent with Figures 4-1 and 4-2.
Predicted flux oufe-of the landfill into the Zone 2 aquifer
is significantly greater with leachate interception than
with Alternative 4c, particularly after 5 to 6 years. The
cumulative leachate flow into the environment from the
landfill under the leachate interception scenario exceeds
the amount for Alternative 4c. Further, supporting evidence
for the interception system's "high degree of reliability
that the leachate seeps will be eliminated" has not been
provided (see comment 8 above).
** EPA notes that ammonia nitrogen is also a major contaminant of concern
discharging from the Tulalip Landfill.
E-6
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11. Page 13, Section 3.6: The technical implementability
discussion should have included consideration of the long
term potential need for pretreatment requirements that could
be set by the receiving POTW based upon new effluent limits.
As indicated in the comment regarding Section 2.5.2, both
Ecology and the Everett POTW anticipate new limitations.
12. • Discussions of administrative implementability should have
included the following:
a. Effluent limits for the Marysville POTW were recently
developed based on the current wastestreams. New
wastestreams could require revisions to the permit.
The POTW authority may be hesitant to go through this
process again so soon. Also, contacts at this POTW
indicate that several months of continuous monitoring
data would be required to assess the characteristics of
the wastestream prior to acceptance. Local limits for
the discharges to the POTW are expected to be developed
sometime next year, and may also trigger pretreatment
requirements.
b. Local ordinances can restrict POTWs from accepting
waste streams from outside their established service
areas. This issue should have been evaluated and
discussed for the Everett and Marysville POTWs.
13. Page 13, Section 3.7: Given the numerous technical
uncertainties associated with Alternative 2b(ii), EPA has
developed a more realistic cost estimate for the alternative
using assumptions that are more appropriately conservative.
EPA estimates the cost for Alternative 2b(ii) to be $20.8
million (see"attached table). EPA's assumptions used for
the cost estimate include:
• A lower horizontal permeability for the refuse was
assumed and the trench spacing was reduced to 200 feet.
• Conventional excavation techniques were assumed with
trench integrity being maintained by shielding or
trench boxes or sloping. Excess trench spoils were
assumed to be disposed in a municipal landfill.
• Due to the likelihood of trench spoils being saturated,
it was assumed the spoils were dewatered on a pad of
HOPE and drainage media.
• EPA assumed regrading, placement of imported cover
material, and revegetation of over 1/2 of the landfill
would be necessary to prevent human exposure of wastes
and contaminated soil.
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• The quantity of gravel backfill was increased to 23,000
cubic yards. This amount assumes the trench to be 4.2
feet wide and the depth of gravel to be 5 feet (5' deep
x 4.2' wide x 29,600' long = 23,022 cubic yards).
• Waste disposal costs were increased to $60/cubic yard
to reflect disposal facility tipping fees ($42/cubic
yard) as well as loading and hauling costs ($18/cubic
yard).
• Operation and maintenance (O&M) costs for the 24
extraction sumps was increased to $30,000. This value
assumes monthly inspections and periodic repair and/or
replacement of each pump at an annual cost $1,250 per
pump.
• Costs for POTW disposal were increased based on
estimates from the POTWs.
• Annual maintenance of the sumps and trenches to
eliminate siltation build-up and biofouling; includes
periodic replacement of drainage media in the
interceptor trenches.
14. Page 15, Section-.4 .1:
iar
-**•*•»
• The third sentence of the second paragraph is
incorrect. Evidence suggests that potential surface
,water ARARs are not achieved at the point where
groundwater discharges to surface water.
• The document's claim that degradation of a low
permeability cover should be expected as a result of
"surface activities and natural weathering" is
unfounded. As the Respondents in the past have stated,
an engineered cap would support the expected future
land use activities. Further, exposure of the cover,
and therefore degradation to natural weathering would
not normally be expected. To suggest that degradation
from future land use or weathering is eminent or even
likely is misleading.
15. Page 17, Section 4.3: The last sentence is misleading and
should have been omitted. Deterioration of an FML layer in
a properly constructed cover system is improbable; membrane
liners subjected to intense accelerated aging tests have
routinely demonstrated that geosynthetics should last almost
indefinitely. Other potential breaches from punctures or
tears are equally unlikely when accounting for the
anticipated loading with respect to the design strengths of
the geosynthetic materials available. Field seams would be
aggressively tested to insure water-tightness, and a quality
E-8
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assurance program, as well as field placement oversight,
would provide a final safeguard against leaks caused by
improper installation.
16. Attachment A: The data provided by the Respondents to the
POTW regarding the Respondent's expectations of the leachate
and its wastewater characteristics should have been provided
•in this attachment.
17. Page B-l, Attachment B: This attachment provides an
"apples-to-oranges" comparison because it treats sites that
include caps the same as sites that don't. For a proper
comparison, the average cost per acre should only include
costs for sites employing low permeability caps. In doing
so, the appropriate average cost per acre for landfills that
are truly greater than'80 acres is $173,000, compared to an
estimated cost of $171,000 per acre for Alternative 4c. In
addition, EPA notes that the cost estimates presented on
page B-l should have been adjusted for inflation, which
would further increase the $173,000 figure relative to the
selected Alternative (4c). EPA, concludes that the cost per
acre for Alternative (4c) is comparable or less than the
cost per acre for landfills of similar size.
E-9
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EPA Cost Estimate for Alternative 2b(ii) - Leachate Seep Collection with
Discharge to Publicly Owned Treatment Works (POTW)
Table 1
n
=>(TAL COSTS
Signs
Deed Modification
Monitoring Plan
Clearing and Grubbing
Surface Regrading
Pre-desJgn Testing
Permitting/Easements/Crossings
Interceptor Trench
Excavate Trench & Haul to Stockpile
Stockpile Pad
Place Perforated Pipe
Gravel Backfill
Waste Disposal
Soil Cover
Extraction Sumps
Cover
Regrade on-srte Soil
Cover Material
Vegetation
Prepare Cover Material
Pipeline
On-srte Pipeline with Trench
Pump Station
Pipeline to POTW with Trench
Pipeline Monitoring/Controls
POTW Hookup Charges
Subtotal Capital Costs
Contractor Overhead & Profit
Engineering
Construction Surveillance
Contingency
tal Capital Cost*
•oration and Maintenance (O&M) Costs
POTW Discharge fees
POTW InspjMonit Fees
Pump Station Operation/Maintenance
Trench Maintenance/Cteanout
Sump Maintenance
Annual Groundwaver Monitoring Costs
Sign & Gate Maintenance
Subtotal O4M Costs
Contingency
O&M Costs
t Present Value of O&M Costs
tal Alternative Cost (Net Present Value)
Quantity
24
1
1
18
1
1
1
78.620
10.000
29.600
23;000
32.360
15,350
24
150.000
118.000
73
118.000
4.000
1
21.000
1
56
58
30
Units
each
US
LS
Acres
US
US
US
CY
SF
LF
CY
CY
CY
Each
CY
CY
Acre
CY
LF
US
LF
LS
MGalfyr
MGal/yr
per annum
per annum
per annum
per annum
per annum
per annum
years
Unit Cost
$500
$5.000
$50.000
$3.500
$100,000
$500.000
$200.000
$8
$3
$12
$14
$60
$10
$15,000
$2
$12
$1,500
$1
$25
$100.000
$25
$30,000
$33,000
10%
8%
3%
25%
$4,400
$4.000
$10,000-
$20,000
$30.000
$50,000
$3,000
25%
Cost
$12.000
$5.000
$50.000
$63,000
$100,000
$500,000
$200,000
$628.960
$30.000
$355.200
$322.000
$1.941,600
$153,500
$360.000
$300.000
$1,416.000
$109.500
$118,000
$100,000
$100.000
$525.000
$30.000
$1,914,000
$9.333,760
$933,376
$746,701
$280,013
$2.333,440
$13.627,290
$255,200
$4.000
$10,000
$20,000
$30.000
$50.000
$3,000
$372,200
$93,050
$465.250
$7,152,033
$20,77*9,322
Notes
1 7 ft average depth, conventional
-->«•=».
12 in dia. pipe
5 ft deep
Municipal Landfill
2 ft deep
Assumes covering 1/2 the landfill
Locally available select material
Conventional seeding
Rod
3 ft deep, 2 ft wide
400 gpm pump
3 ft deep, 2 ft wide
Deludes sediment removal
•
Discount Rate - 5%
E-10
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