EPA Superfund
Record of Decision:
PB94-964642
EPA/ROD/R10-93/069
February 1995
Harbor Island (Lead),
Seattle, WA
9/30/1993
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R10-93/069
3. Recipient's Accession No.
4. TUb and Subtitle
SUPERFUND RECORD OF DECISION
Harbor Island-Lead, WA
First Remedial Action
5. Report Date
09/30/93
7. Authors)
8. Performing Organization Rapt No.
nlng Organization Nairn and Address
10 Project T«»kWork Unit No.
11. Contract(C)orGrant(G)No.
(C)
12. Sponsoring Organization Harm and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/800
14.
15. Supplementary Notes
PB94-964642
16. Abstract (Limit: 200 words)
The 400-acre Harbor Island-Lead site is a man-made industrial island in Seattle, King
County, Washington. Land use in the area is predominantly commercial and industrial,
with residential properties to the west of the site. The site lies at the mouth of the
Duwamish Waterway on the southern edge of Elliott Bay, in the inland marine waterway
known as Puget Sound. Ground water on Harbor Island currently is not used for drinking
water, and all water users on the island are serviced by the City of Seattle municipal
water system. Prior to 1985, the area consisted of tidal flats and a river mouth delta
with some piling-supported structures. Initial construction of the island began
between 1903 and 1905 when dredging of the East and West waterways and the main
navigational channel of the Duwamish River occurred. Since its construction, major
activities at Harbor Island have included ocean and rail transport operations, bulk
fuel storage and transfer, secondary lead smelting, lead fabrication, shipbuilding, and
metal plating. Warehouses, laboratories, and office buildings also have been located on
the island. In 1937, a secondary lead smelter was constructed near the center of
Harbor Island. In 1979, State investigations showed that the quarterly average ambient
air concentration of lead from smelter activities exceeded the Federal standard for
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Harbor Island-Lead, WA
First Remedial Action
Contaminated Media: soil, gw, sw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes), other organics (oils,
PAHs, PCBs), metals (arsenic, chromium, lead)
b. Identifiers/Open-Ended Terms
c. COSATI Raid/Group
18. Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
102
22. Price
(See ANSI-Z39.18)
Sf* Instructions on Reverse
OPTIONAL FORM 272 (4-77)
•ms-35)
I of Commerce
(Formerly NTIS-35)
Department^"
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EPA/ROD/R10-93/069
Harbor Island-Lead, WA
First Remedial Action
Abstract (Continued)
lead ninety-five percent of the time. Subsequently, in 1982, an EPA inspection identified
a significant volume of lead-contaminated soil at the onsite lead smelter facility. In
1984, the lead smelter ceased operations, but the facility later was subject to a RCRA
enforcement action in conjunction with the closure of a surface impoundment. As part of
this RCRA action, ground water monitoring wells were installed and soil borings were
taken, which identified elevated concentrations of lead at the facility. In 1985, State
investigations revealed numerous types of contaminants, including metals, PAHs, PCBs,
petroleum products, and a floating product at the shipyard facility; all of which were a
result of past smelting and improper disposal activities. In 1990, EPA required the City
of Seattle to clean contaminated sediment from its storm drain system on Harbor Island.
In 1991, EPA required a PRP to remove and dispose of approximately 80 drums of spent
electroplating solution off site. EPA has divided the site into four OUs for remediation.
This ROD addresses the island-wide unit, which includes all contaminated soil, ground
water, surface water, and NAPLs, as OU1. Future RODs will address the petroleum tank
farms, the Lockheed Shipyard, and the marine sediment from Harbor Island, as OUs 2, 3, and
4, respectively. The primary contaminants of concern affecting the soil, ground water,
surface water, and NAPLs are VOCs, including benzene, PCE, TCE, toluene, and xylenes;
other organics, including oils, PAHs, and PCBs; metals, including arsenic, chromium, and
lead.
The selected remedial action for this site includes excavating and onsite stockpiling
of soil containing the highest levels of organic contamination ("hot spots"), defined as
Total Petroleum Hydrocarbons (TPH) greater than 10,000 mg/kg, PCBs greater than 50 mg/kg,
and soil with mixed carcinogens 'with a total risk greater than 10~^; treating 91,000 yd^
of TPH-contaminated soil onsite using thermal desorption; backfilling the excavated areas
with clean soil; testing and solidifying, if necessary, the TPH-contaminated soil from the
treatment process prior to onsite disposal; capping the TPH-contaminated soil that passes
leachability testing, but contains contaminants with concentrations above cleanup goals;
recycling, if possible, or disposing of the waste oil offsite; treating 2,000 yd^ of
PCBs-contaminated soil offsite using incineration or disposing of it at a hazardous waste
disposal facility; disposing of 1,200 yd^ of organic "hot spot" soil with risk greater
than 10~^ in a hazardous waste disposal facility; capping 40 acres of exposed contaminated
soil exceeding inorganic or organic cleanup goals with a low permeability cap; repairing
existing asphalt and concrete surfaces to prevent infiltration of rainwater; pumping and
treating contaminated ground water and associated floating petroleum product onsite using
an oil water separator, followed by air stripping and carbon adsorption, with offsite
discharge of the treated water to a POTW and offsite recycling or disposing of the
recovered floating petroleum product; monitoring ground water; implementing engineering
controls to control runoff and prevent soil from being transported into the island storm
sewer system; conducting training and meetings to inform workers of site hazards;, and
implementing institutional controls, including deed restrictions. The estimated present
worth cost for this remedial action is $40,192,548, which includes an estimated present
worth O&M cost of $33,000,000 for 30 years.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific soil cleanup goals are based on risk standards set forth in the State of
Washington Model Toxics Control Act, and include TPH greater than 10,000 mg/kg; PCBs
greater than 50 mg/kg; and mixed carcinogens with total risk greater than 10" .
Chemical-specific ground water cleanup goals are based on protection of marine organisms
or human health from consumption or organisms with greater than 10~6 risk, and include
arsenic 36 ug/1; benzene 71 ug/1; cadmium 8 ug/1; carbon tetrachloride 4.4 ug/1; copper
2.9 ug/1; cyanide 1 ug/1; lead 5.8 ug/1; mercury 0.025 ug/1; nickel 7.9 ug/1; PCBs 0.03
ug/1; PCE 8.8 ug/1; silver 1.2 ug/1; TCA 42 ug/1; thallium 6.3 ug/1; and zinc 76.6 ug/1.
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RECORD OF DECISION
DECLARATION, DECISION SUMMARY,
AND RESPONSIVENESS SUMMARY
FOR
HARBOR ISLAND SOIL AND GROUNDWATER
SEATTLE, WASHINGTON
SEPTEMBER 1993
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 10
1200 SIXTH AVENUE
SEATTLE, WASHINGTON
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TABLE OF CONTENTS
Section Page
I. Declaration
II. Decision Summary
Introduction ....... 1
Site Name, Location and Description 1
Site History and Enforcement Activities 4
Highlights of Community Participation 7
Scope and Role of Response Action 8
Summary of Site Characteristics 10
Summary of Site Risks 16
Remedial Action Objectives 24
Description of Alternatives 26
Summary of the Comparative Analysis of Alternatives 66
The Selected Remedy : 72
Statutory Determinations 81
Documentation of Significant Changes 85
Appendices
Appendix A: Responsiveness Summary
Appendix B: Method for Selecting Hot Spot Treatment Levels
Appendix C: Administrative Record Index (Renewed)
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List of Figures
Figure l: Harbor Island Location Map 2
Figure 2: Harbor Island Facilities 3
Figure 3: Harbor Island Operable Units 9
Figure 4: Surface Soil Exceeding Cleanup Goals ... 27
Figure 5: Soil Hot Spot Locations 44
Figure 6: Contaminated Areas to be Capped 74
List of Table:;
Table 1: Potential Sources of Contamination 5
Table 2: Maximum Surface Soil Concentrations 17
Table 3: Summary of Industrial Exposure Intake Factors 18
Table 4: Summary of Commercial Exposure Intake Factors 19
Table 5: Summary of Noncancer Risk Calculations . . 22
Table 6: Summary of Cancer Risk Calculations .... 22
Table 7: Remedial Action Objectives and Cleanup Goals 25
Table 8: Volumes of Soil Exceeding Cleanup Goals . . 26
Table 9: Soil Hot Spot Treatment Levels 43
Table 10: Organic Hot Spot Volumes 46
Table 11: Present Worth Cost for Remedial Alternatives 71
Table 12: Soil Remediation Alternative Costs .... 78
Table 13: Groundwater Remediation Alternative Costs 80
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DECLARATION
SITE NAME AND LOCATION
Harbor Island
Seattle, King County, Washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected final remedial action,
for soil and groundwater, for the Harbor Island Site in Seattle,
King County, Washington, which was chosen in accordance with the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) (42 U.S.C. §§ 9601-96), as amended, and, to the extent
practicable, the National Contingency Plan (NCP). This decision is
based on the Administrative Record.
The Washington State Department of Ecology (Ecology) concurs with
the selected remedy given the specifics found at this site.
This decision document excludes three separate operable units on
Harbor Island: the Shell, Arco, and Texaco petroleum tank farms;
Lockheed Shipyard; and marine sediments. EPA has designated
Ecology as the lead agency for the three petroleum tank farm
facilities on the island. The primary contamination at these
facilities is petroleum, which is generally excluded from the
definition of a hazardous substance in CERCLA but is a regulated
hazardous substance under the State's Model Toxics Control Act
(MTCA). Ecology intends to issue a decision document for the tank
farm unit in early 1995.
The Lockheed Shipyard on Harbor Island has been designated as a
separate operable unit and EPA anticipates that it will issue a
separate decision document for this unit in early 1994. Marine
sediments around Harbor Island have also been designated as a
separate operable unit and EPA anticipates that it will issue a
separate decision document for this unit in late 1994.
ASSESSMENT OF THE FACILITY AND ADJACENT AREAS OF CONTAMINATION
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 and
substantial endangerment to public health, welfare or the
environment.
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DESCRIPTION OF THE SELECTED REMEDY
The remedial action described in this Record of Decision represents
a final remedy for treatment of Harbor Island soil and groundwater,
except for those areas identified above as separate operable units.
The remedial action presented in this ROD addresses the risks to
human health and the environment by:
1) Excavation and treatment of the soil containing the highest
levels of organic contamination ("hot spots"). These
organic soil hot spots are defined as Total Petroleum
Hydrocarbons (TPH) greater than 10,000 mg/kg, PCBs greater
than 50 mg/kg, and soil with mixed carcinogens with a total
risk greater than 10"*. TPH hot spot soil will be treated
en site in a thermal desorption unit. PCBs hot spot soil
will either be sent off site for treatment (incineration)
or be disposed in a hazardous waste disposal facility.
Organic hot spot soil with risk greater than 10"* will be
disposed in a hazardous waste disposal facility.
2) Capping exposed contaminated soil exceeding inorganic or
organic cleanup goals. The cap would consist of a low
permeability material such as asphalt to prevent
infiltration of rainwater and reduce contaminant migration
into the environment. Existing asphalt and concrete
surfaces would be repaired to also prevent infiltration of
rainwater.
3) Invoking institutional controls which would require long
term maintenance of new and existing caps, warn future
property owners of remaining contamination contained under
capped areas on their properties, and specify procedures
for handling and disposal of excavated contaminated soil
from beneath the capped areas if excavation is necessary in
the future.
4) Removal of and treatment of floating petroleum product and
associated contaminated groundwater at Todd Shipyards to
prevent its migration into the marine environment.
Implementing groundwater monitoring for 30 years, with
review of groundwater quality trends every 5 years to
assess the effectiveness of the selected remedy.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with state and federal requirements that are
legally applicable or relevant and appropriate to the remedial
actions, and is cost effective. This remedy uses permanent
solutions and treatment technologies to the maximum extent
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practicable for this site by treating the most highly contaminated
areas and capping less contaminated areas. This remedy satisfies
the statutory preference for remedial actions that employ treatment
to reduce toxicity, mobility and
Because this remedy will leave some hazardous substances on site
above cleanup goals, a review of the site and its remedy will be
conducted within five years after initiation of the remedial action
to ensure the remedy continues to provide adequate protection of
human health and the environment.
7-
Gerald A. Emison Date
Acting Regional Administrator, Region 10
U.S. Environmental Protection Agency
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DECISION SUMMARY
HARBOR ISLAND, SEATTLE, WASHINGTON
INTRODUCTION
The Harbor Island site, Seattle, King County, Washington, was
listed on the National Priorities List (NPL) as a Superfund site in
1983 due to elevated lead concentrations in the soil from a lead
smelter on the island, as well as elevated concentrations of other
hazardous substances. The site was ranked number 738 in the
Hazardous Ranking System (HRS) based on a site assessment performed
by the United States Environmental Protection Agency (EPA) in 1985,
pursuant to Section 105 of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980, 42 U.S.C. §
9605, as amended, (CERCLA).
Pursuant to Executive Order 12580 (Superfund Implementation) and
the National Oil and Hazardous Substances Pollution Contingency
Plan (NPC) , 40 C-F-R- Part 300, EPA performed a Remedial
Investigation/Feasibility Study (RI/FS). The Remedial
Investigation (RI) characterized contamination in soil, surface
water and groundwater at the facility. The RI .was completed in
1992. A (baseline) risk assessment was completed as part of the RI
and evaluated potential effects of the contamination on human
health and the environment. The Feasibility Study (FS), completed
in February 1993, evaluated alternatives for remediating
contamination.
SITE NAME, LOCATION, AND DESCRIPTION
Harbor Island is located about one mile southwest of downtown
Seattle, in King County, Washington (Figure 1) . It lies at the
mouth of the Duwamish Waterway on the southern edge of Elliott Bay,
in the inland marine waterway known as Puget Sound. The island
occupies large portions of Sections 7 and 18 in Township 24, Range
4, and smaller portions of Sections 12 and 13, Township 24, Range
3. The flat-lying island covers an area of approximately 400
acres, and is bordered on either side by the East Duwamish and West
Duwamish waterways. Elevation of the island varies from about 12
to 15 feet above sea level. There are no wetlands on the island and
no endangered or threated species are known to inhabit the island.
Harbor Island is zoned exclusively as General Industrial, with the
exception of a 200-foot shoreline zone that is designated as Urban
Industrial. Major facilities and structures on the island are shown
in Figure 2. Almost the entire eastern side of the island is
occupied by the Port of Seattle Terminal 18 cargo container
facility. The interior of the island is occupied by numerous small
to medium sized businesses including Seattle Foundry Company, Aspen
Points, Value Metal Plating, Pacific Rendering, Harbor Island
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Figure 1
Harbor Island Location
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Figure 2
Harbor Island
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Machine Works, and other metal fabricating companies. Arco,
Texaco, and Shell maintain petroleum tank farms in the central
portion of the island. Stevedoring Services of America operates a
•^'pping and receiving dock with a cc. tainer storage area along the
north portion of the island. Todd Shipyard, a large shipbuilding
facility, occupies the northwest corner of the island. A portion
of the western side of the island is owned by Lockheed Corporation
and was at one time used for shipbuilding. A concrete company, a
marina, and a fishing pier are located on the southern part of the
island. Commercial developments on the island include retail and
wholesale establishments, offices, restaurants, and parking areas.
Approximately 70 percent of Harbor Island is covered with
buildings, roads, or other impervious substances (e.g., concrete
pads, parking lots). There are three main roads that run north and
south: llth Avenue SH, 13th Avenue SW, and 16th Avenue SE; and
three streets that run east and west: Hanford, Klickitat, and
Florida. Union Pacific railroad lines extend through the median of
llth Avenue SW and 16th Avenue SW. Union Pacific also operates a
railroad switching facility on the northern end of the island,
providing railroad spurs which lead to barge loading docks and
industrial facilities.
Water and/or waste water generated on Harbor Island is transported
via the Metro Sanitary Sewer Collection System to the West Point
Metro sewage treatment plant. Storm water runoff is diverted into
the Puget Sound through a storm sewers. Storm water is discharged
into the East and West Waterways through municipal and privately
owned outfalls around the perimeter of the island.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
Harbor Island is a man-made industrial island covering about 400
acres located at the mouth of the Duwamish River in Seattle,
Washington. Prior to 1885, the area consisted of tideflats and a
river mouth delta with some piling-supported structures. Initial
construction of the island began between 1903 and 1905 when
dredging of the East and West waterways and the main navigational
channel of the Duwamish River occurred. Dredged sediment was spread
across the present island area to form a fill 5 to 15 feet thick.
This dredged sediment was later covered with soil and demolition
debris from Seattle regrade projects. Since its construction, the
island has been used for commercial and industrial activities.
Major activities have included ocean and rail transport operations,
bulk fuel storage and transfer, secondary lead smelting, lead
fabrication, shipbuilding, and metal plating. Warehouses,
laboratories, and office buildings also have been located on the
island. The secondary lead smelter was originally constructed on
Harbor Island in 1937 and was located near the center of the
island.
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Concern over the levels of lead in the air, due to the operation of
the lead smelter, prompted several air monitoring studies during
the 1970s. A study conducted in 1979 by the Puget Sound Air
Pollution Control Agency (PSAPCA) showed tha . the quarterly average
ambient air concentration of lead exceeded the federal standard for
lead of 1.5 A*g/m3 95% of the time. Subsequently, a site inspection
conducted by EPA in 1982 identified a significant volume of lead
contaminated soil at the lead smelter facility. As a result of this
site inspection, the island was listed on the tJPL in 1983.
The lead smelter ceased operation in 1984, but the facility later
was subject to a RCRA enforcement action in conjuction with the
closure of a surface impoundment. As part of this action,
groundwater monitoring wells were installed and soil borings were
taken to determine soil quality. Elevated concentrations of lead,
cadmium and sulfate were found at the facility. A groundwater
monitoring program is now in effect which requires periodic
sampling of the groundwater to ensure that the closed lagoon is not
acting as a contaminant source to the groundwater.
In 1985, the Department of Ecology performed a preliminary
investigation of the site to further define the nature and extent
of contamination on the island. This investigation, and subsequent
investigations, revealed numerous other types of contaminants in
addition to lead, including: cadmium, chromium, arsenic, copper,
zinc, mercury, polycyclic aromatic hydrocarbons (PAHs),
polychlorinated biphenyls (PCBs), and petroleum products. Table 1
identifies some of the potential sources of these contaminants on
the island.
Table 1 - Potential Sources of Contaminants
Contaminants Sources (Present and Historical)
Metals -Metal smelting and refining
-Metal plating operations
-Scrap metal recycling
-Paint pigments
-Battery recycling
-Waste oil
-Automotive emissions
Polychlorinated -Transformer oils
Biphenyls (PCBs) -Heat transfer fluids
-Metal cutting oils
Polycyclic Aromatic -Incomplete combustion of
Hydrocarbons (PAHs) organic matter
-Automotive and truck exhausts
-Diesel and fuel oil. petroleum
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In 1986, approximately 220 parties were sent 104(e) information
request letters by EPA. Based on the responses received, a
Potentially Responsible Party (PRP) search was completed for Harbor
Island in 1987. Since many of the facilities on the island had
multiple owners and operators, the search identified approximately
150 PRPs. These PRPs- were subsequently sent "general notice"
letters. As a result of further .evaluation of PRP list, EPA removed
about 50 parties from the PRP list in 1989, bringing the current
total of PRPs to 98.
In 1987, EPA planned a Phase I RI which included only areas on the
island where there had been a known release of hazardous substances
from past operations. In an attempt to have this work performed by
the PRPs, EPA sent "special notice" letters to 13 PRPs stating that
EPA intended to conduct a remedial investigation unless the PRPs
agreed to perform the work. EPA subsequently elected to perform the
work with federal funds because EPA could not reach an agreement
with these 13 PRPs. The Phase I investigation was initiated in 1988
and completed in 1990.
During implementation of the Phase I RI, EPA negotiated a Consent
Order with the City of Seattle. Under the terms of this Order, the
City of Seattle cleaned contaminated sediments from its storm drain
system on Harbor Island. These storm drains were considered a major
pathway for contaminants entering the surrounding waters and marine
sediments. The work under this Order was completed in the Spring of
1990 and the City is now periodically monitoring the discharge from
these stormdrains to ensure that they meet water quality standards.
In a separate enforcement action, EPA negotiated a Consent Order
for a removal with the owner of the Value Metal Plating facility in
January, 1991. This Order required the removal and off-site
disposal of about 80 drums of spent electroplating solution. The
work under this Order was completed in December, 1992.
Before proceeding with the next phase of the RI/FS, EPA decided to
break up the Harbor Island site into several operable units which
could be managed more efficiently. Initially, six areas were
defined as potential operable units: the petroleum tank farms, Todd
Shipyard, Lockheed Shipyard, Terminal 18, the island-wide unit, and
the marine sediment unit. The petroleum tank farm unit consists of
three tank farms owned by Shell, ARCO, and Texaco. Since petroleum
is generally excluded from the definition of hazardous substance
under CERCLA but is a hazardous substance under the State's Model
Toxics Control Act (MTCA), EPA and Ecology signed a memorandum of
agreement that gives Ecology the lead in undertaking enforcement
actions for these three tank farms. Agreements between Ecology and
the tank farm owners to conduct RI/FSs were finalized in early 1993
and the selection of remedial actions is scheduled for early 1995.
Todd Shipyard and Lockheed Shipyard were sent special notice
letters requesting that they conduct an RI/FS on their facilities
in June, 1990. In September, 1990, a Consent Order was signed with
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Lockheed and the Record of Decision for this unit is scheduled for
the Spring of 1994. Negotiations were terminated with Todd due to
submission of an inadequate good faith offer. An RI/FS special
notice letter was sent to the Port of Seattle for Terminal 1C. in
January, 1991, but negotiations were terminated after the Port
decided not to conduct the work. Both the Todd Shipyard and
Terminal 18 facilities were then added to the island-wide operable
unit.
The island-wide operable unit includes the entire island except for
Lockheed Shipyard and the petroleum tank farms. The Phase II RI
field work for this unit was initiated in May, 1991, and involved
sampling soil at approximately 300 locations and installing 49
groundwater monitoring wells. The RI/FS reports for1 the island-wide
operable unit were completed in February, 1993. The RI field work
for the marine sediment unit was initiated in September, 1991, and
involved sampling marine sediments at over 100 locations around the
island. The marine sediment RI/FS reports are scheduled for
completion in the Spring of 1994. The ROD for the marine sediment
unit is scheduled for the fall 1994.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
CERCLA requirements for public participation include releasing
the Remedial Investigation and Feasibility Study 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 in May, 1993, by placing both documents in the public
information repositories for the site. EPA mailed copies of the
Proposed Plan in June, 1993, to about 300 individuals on the
mailing list. EPA published a notice of the release of the RI/FS
and proposed plan in the Seattle Times in the morning and evening
editions on June 23, 1993. Notice of the 30 day public comment
period and the public meeting discussing the proposed plan were
included in the newspaper notice. The public meeting was held on
July 14, 1993, at the EPA Region 10 Headquarters on Sixth Avenue in
Seattle. A request for a 30 day extension of the public comment
period was received by EPA and was granted, extending the comment
period to 23 August 1993. Public comments received and EPA's
responses are located in the attached Responsiveness Summary
section.
To date, the following community relations activities have been
conducted by EPA at the Harbor Island site over the past 5 years:
March 1988- EPA updated the Community Relations Plan from 1985.
April 1988- EPA released a fact sheet explaining the environmental
problems at the site.
December 1988- A fact sheet was released announcing the beginning
7
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of the Remedial Investigation.
June 1989- EPA mailed an update on the work at the site.
November 1989- A fact sheet was released explaining the work being
conducted by the City... of. Seattle to clean and sample the- storm
drain system on the island.
June 1990- EPA released an update of the activities at the site.
January 1991- EPA released a fact sheet announcing plans to remove
approximately 80 drums and some miscellaneous containers at the
Value Metal Plating facility.
April 1991- EPA released a fact sheet announcing the availability
of the Phase I report and the beginning of the Phase II
investigation.
September 1992- EPA released an update cf site activities.site.
June 231 1993- EPA ran an ad in the Seattle Times announcing the
Public Comment Period and the date and time of the Public Meeting.
June 23, 1993- EPA released the Proposed Plan for site cleanup.
July 9, 1993- EPA releases a notice of the extension to the public
comment period.
August 23, 1993- The Public Comment Period closed.
SCOPE AND ROLE OF RESPONSE ACTION WITHIN THE REMEDIAL STRATEGY
The operable unit addressed by this Record of Decision (ROD) is the
island-wide unit. The remedial action selected in this ROD
addresses all contaminated soil and groundwater exclusive of the
petroleum tank farms and the Lockheed Shipyard, which are separate
operable units as described previously. The marine sediments
contaminated with hazardous substances released from Harbor Island
is the fourth operable unit for this site. The areas covered by
each of these four operable units are shown in Figure 3.
The remedial action selected for this operable unit is the first
action to occur in any of the operable units. It is intended that
the remedial actions to be selected for the Lockheed and tank farm
operable units will be consistent with the remedial actions
selected for the island-wide unit. Contaminated media at Harbor
Island consists of soil, groundwater and sediments. The overall
remedial strategy for Harbor Island is to initiate clean up of
contaminated soil and groundwater first because they pose a risk to
human health and act as sources of contamination to the marine
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Figure 3
Harbor Island Operable Units
Sediments Operable Unit
Lockheed Operable Unit
Tank Farm Operable Unit
I I Harbor Island Operable Unit
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environment. The need for cleanup of sediments and the Lockheed
Shipyard will be the subject of future RODS. Actions necessary to
address the tank farms will be identified by Ecology in a state
ROD. Cleanup of the sediments, *f n»-.:essary, wil-1 occur iiJter
source control identified in this ROD has been initiated.
Sediments at Harbor Island have been contaminated by direct runoff
from contaminated surface soil, indirect runoff through storm sewer
systems, and groundwater contaminant loading. Contamination by
direct and indirect runoff will be controlled by the selected
remedy for this island-wide operable unit through: 1) excavating
and treating organic contaminant "hot spots" in soil, and 2)
capping all areas where contaminants exceed cleanup goals.
Groundwater modeling conducted during the Feasibility Study
indicates that the only significant contaminant loading to surface
water is from floating petroleum product near the shoreline. The
selected remedy will address this source by: 1) pumping and
treating floating petroleum product and associated contaminated
groundwater at Todd Shipyard, and 2) monitor the groundwater
quality for 30 years with review of groundwater quality trends
every 5 years. The selected remedial action on floating product,
followed by Ecology's actions on floating petroleum product
associated with the tank farm operable unit, is expected to meet
the surface water cleanup goals over time and be protective of the
marine sediments.
SUMMARY OF SITE CHARACTERISTICS
General Characteristics
Harbor Island is situated in a geographic area known as the Puget
Lowlands, a trough characterized by low relief, with glacially
shaped bluffs and low rising hills, and a vast area of intertidal
and tidal flats. Puget Sound, in which Harbor Island is located,
is an inland marine waterway formed through continental glaciation.
Harbor Island is located on the former delta of the Duwamish River,
which flows into Elliott Bay and Puget Sound from the Duwamish-
Green River valley.
The island is recognized as one of the largest artificial islands
in the world. The island is composed largely of native fluvial
sand dredged from the surrounding areas. Prior to dredging, the
surface of the delta was intertidal. When the lower Duwamish River
channel and surrounding delta underwent major engineering
modifications in the early 10900s, these former shallow tidal areas
of the Duwamish River delta were filled with material largely
derived from dredging of the Duwamish Channel and adjacent
waterways. Dredged sediment was placed across the Duwamish
tidelands to form a fairly homogeneous sandy fill which is now
Harbor Island. This fine-grained fill consists primarily of poorly
graded, very dark gray, fine to medium, damp to wet, loose sand.
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The fine-grained fill thickness ranges from 3 to 15 feet. Alluvial
deltaic deposits, consisting of unconsolidated, fine to coarse-
grained sand, underlie the fill material. Overlying the fine-
grained fill is a layer of coarse-grained fill which is from
Seattle regrade projects conducted in the early 1900's. This
coarse-grained fill consists of gravelly sand to coarse sand, dark
grayish brown, poorly graded, loose, dry to moist. The thickness
of the coarse-grained fill ranges from 0 to 7 feet.
Adjacent Land Use and Use of Natural Resources
Adjacent Land Use
Harbor Island is located in an area of mixed industrial and
commercial use. Immediately adjacent to the island are similar
industrial areas. Further to the west are residential and
commercial properties. To the east lies the metropolitan Seattle
area, which is primarily commercial with limited residential use.
South of the island are industrial developments.
Use of Natural Resources
Surface water runoff is collected and drained from the site via a
storm drain system consisting of catch basins, outfalls, and
drainage manholes throughout the island. This system discharges at
11 outfalls around the perimeter of Harbor Island and into the East
and West waterways. The East and West waterways are primarily
commercial shipping lanes, but yacht clubs and marinas are
permitted within the shoreline areas. There are no natural ponds
on Harbor Island.
There are no drinking water wells in use on Harbor Island. Harbor
Island groundwater is not currently used for drinking water and all
water users on the island are serviced by the City of Seattle water
system. Groundwater at a depth of approximately 40 feet is
naturally brackish and not potable. Groundwater at Harbor Island is
not considered to be a future drinking water source.
Groundwater Resources
Groundwater at Harbor Island occurs as shallow, unconfined
groundwater within the fill and deltaic sediment. The depth to the
groundwater is shallow and ranges from 2.5 feet to 11 feet below
ground surface (bgs). This groundwater occurs as freshwater and
becomes brackish at depths of 45 feet near the shoreline, and
deeper at inland locations. The water bearing stratographic column
behaves as a single hydrostatigraphic unit.
Groundwater recharge, occurs through infiltration of precipitation.
The groundwater level is highest in the northern half of the
island, where recharge is greatest. Groundwater elevation
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distribution indicates a radial flow condition with discharge to
the adjacent waterways. Groundwater surface elevation decreases
from the north central portion of the island to the southern
portion because a greater percent of :he southern portion is paved,
preventing recharge through infiltration.
The groundwater responds to tidal forces within the adjacent marine
estuary. Areas of the island where tidal forcing is sufficient to
cause a reversal in the direction of groundwater flow are in the
tidally influenced zone, which is 500 feet wide at the northern
portion of the site and may extend to 1,000 feet at portions of the
southern end of the island.
Water levels suggest that the south central portion of the island
is internally drained. The aquifer may be infiltrating the METRO
sewer system in that area.
Known or Suspected Sources of Contamination
Since construction, the island has been used for commercial and
industrial activities. Major activities include shipping, railroad
transportation, bulk fuel storage and transfer, secondary lead
smelting, lead fabrication, shipbuilding, and metal plating.
Warehouses, laboratories, and office buildings have also been
located on the island.
Current sources of contamination were identified in the RI/FS and
include current and past industrial p::c -tices associated with the
activities mentioned above. Based on current information, the
major sources of contamination appear to be:
• Atlantic Richfield Company (ARCO) — tank farm
• Lockheed Shipyard #1
• Nonferrous Metals, Incorporated
The secondary lead smelter, currently Seafab Metal
Corporation
• Seattle Iron & Metals, main yard
• The former Leckenby Company, (Port of Seattle property)
• Shell Oil Co., current tank farm and past tank farm located
on Terminal 18 (Port of Seattle)
• Texaco USA — tank farm
• Todd Shipyards
Types of Contamination and Affected Media
The Harbor Island RI involved the collection of surface and
subsurface soil samples from over 300 locations. Soil sample
locations were based on a combination of a grid pattern over the
entire island and additional (biased) sampling in areas of
suspected or known contaminant releases. Surface soil samples were
taken from the top 6 inches of soil and subsurface soil samples
were taken at at intervals of 0.5-3.0, 3.0-6.0, and 6.0-10.0 feet.
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Groundwater samples taken from approximately 69 monitoring wells
(49 new wells and 20 existing wells) . The intent of the sampling
was to characterize the extent of contamination. The results of
the sampling efforts for each medium are presented in the RI report
and are summarized below.
Surface Soil (O-6 Inches)
Surface soil is contaminated with elevated levels of organic
compounds and inorganic elements over a major portion of the
island. By volume, the most significant organic contaminant in
surface soil is petroleum products [total petroleum hydrocarbons
(TPH) ]. Approximately 95 percent of the samples with detectable
TPH concentrations were between 20 mg/kg and 51,000 mg/kg, although
most were between 50 and 2,000 mg/kg. Also present in smaller
quantities in surface soil were polycyclic aromatic hydrocarbons
(PAHs). The highest concentrations of heavy PAHs found in surface
soil ranged between 10 and 50 mg/kg. Polychlorinated biphenyls
(PCBs) in surface soil ranged from 2 to 420 mg/kg. TPH and PAHs
were found mainly around the petroleum tank farms, and at Seattle
Iron and Metals 'and Todd Shipyard facilities. PCBs were found
predominantly in the central portion of the island.
The most significant inorganic contaminant on the island is lead,
which is found over most of the island and originated primarily
from the lead smelter. Approximately 55% of the surface soil
samples and 12% of the subsurface soil samples exceeded a
concentration of 1,000 mg/kg. The highest detected concentration
was 401,000 mg/kg. Lead contamination was primarily confined to the
upper three feet of soil. The majority of samples with elevated
lead in the range from 5,000 to 200,000 mg/kg, occurred in the
central portion of the site. The highest concentrations of other
inorganics are found in surface soil include: arsenic at 1,830
mg/kg, cadmium at 131 mg/kg, and chromium at 791 mg/kg. The highest
concentrations of most inorganic contaminants in surface soil are
located in the central portion of the island and are associated
with industrial operations in that area.
TCLP tests conducted on surface soil samples showed that leachate
for lead exceeded the RCRA threshold for a characteristic waste at
six locations.
Subsurface Soil (Below 6 inches)
Subsurface soil is also contaminated with the same organic
compounds and inorganic elements found in surface soil, but
contaminated subsurface area decreases rapidly with depth. The
major organic subsurface contaminant is TPH, which ranges from
nondetect to 90,517 mg/kg in subsurface soil. TPH contamination is
associated with the petroleum t?nk farms, Seattle Iron and Metals,
and Todd Shipyard facilities. High concentrations of TPH are
located at depths from 0.5 to 10 feet below the surface in these
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areas.
PAH concentrations in subsurface soil range from below the
detection limit to 182 mg/kg. Approximately 90 percent of the
subsurface soil contains less than 5 mg/kg heavy PAHs. PCBs in
subsurface soil range from 0.02 to 5.48 mg/kg.
The most significant inorganic contaminants found in subsurface
soil are lead and mercury. Lead contamination ranges from 2.3 to
32,200 mg/kg and mercury from 1.0 to 8.1 mg/kg. The highest
concentrations of lead are found in the vicinity of the old lead
smelter at depths of 0.5 to 10 feet, and the highest concentrations
of mercury are located at depths of 0.5 to 3 feet at the Seattle
Iron and Metal and Todd Shipyard facilities.
Groundwater
The results of the remedial investigation show that measurable or
trace amounts of light nonaqueous phase liquid (floating product)
is present in eight wells associated with the petroleum tank farms
and three wells associated with Todd Shipyards. The only location
where significant floating product is found near the shoreline is
at Todd Shipyards. Components of this floating product include
diesel fuel and gasoline. Thicknesses ranged from a sheen to 7
inches.
Groundwater at several locations along the shoreline on the
northern portion of the island also contained benzene,
ethylbenzene, and xylene, vinyl chloride, and other compounds
associated with petroleum products. Benzene ranged from nondetect
to 3,900 Aig/L, ethylbenzene from nondetect to 1,800 pg/L, O-xylene
from nondetect to 16,000 ^g/L, and vinyl chloride from nondetect to
7.0 /xg/L.
Elevated levels of inorganic contaminants including mercury,.
nickel, cadmium, lead, and zinc are also found in groundwater
across the island. Mercury ranges from nondetect to 3.0 M9/L/
nickel from nondetect to 230 Mg/L, cadmium from nondetect to 21
jig/L, lead from nondetect to 64 Mg/L/ and zinc from nondetect to
1,700 M9/L- Ammonia is also present in elevated levels in the
groundwater.
Based on the results of a groundwater model (FLOWPATH) which EPA
used to predict the rate of migration of the above contaminants.to
the shoreline (where marine organisms could be exposed), it was
determined that most of the contaminants currently in the
groundwater would not reach the shoreline within 50 years. The
only contaminants which are at the shoreline now or will be there
in the next 50 years are the floating petroleum product at Todd
Shipyards and low levels of VOCs dissolved in the groundwater at
Todd Shipyards and two other locations along the shoreline.
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Routes of Migration
The fate of contaminants originating from Harbor Island depends on
location-specific migration patlrv.ys . ^nd or. the chemical and
physical properties of each contaminant. This section focuses on
the contaminants of concern and identifies their probable routes of
migration in surface soil, subsurface soil, and groundwater.
A transport of contaminants was established by review of storm
drain analytical data and examination of RI maps depicting the
concentration distributions for contaminants of concern in soil,
groundwater, and offshore sediment. The presence of localized,
elevated concentrations of contaminants in two or more media
connected by a transport pathway (e.g., spil/groundwater or surface
soil/storm drain/sediment) was considered evidence of contaminant
release and transport.
Surface Soil
The principal transport mechanisms of the contaminants in surface
soil are as suspended soil in surface water runoff. Surface water
runoff is a significant current transport pathway for contaminants
to reach the surrounding waterways and marine sediments. Surface
water runoff can transport dissolved, suspended, and particulate-
bound contaminants through storm drains into the surrounding
estuary.
Subsurface Soil
The probable transport mechanism of the primary contaminants in
subsurface soil is vertical transport of dissolved contaminants in
rainwater which permeates through the soil. The primary factor
which determines the rate which inorganic and organic contaminants
leaches from the soil is the contaminant solubility. For
inorganics, the pH of the water contacting the contaminated soil is
also an important factor. Inorganics are relatively less mobile in
the soil than organics because inorganics have relatively low
solubility in water and they also strongly adsorb to soil
particles, particularly silts and clay. Organics, on the other
hand, are generally more soluble in water and primarily bind to
naturally occurring soil organic matter, such as humic acid.
Organic contaminants in high concentrations, such as petroleum, can
also travel through pores in the soil as a Non-Aqueous Phase Liquid
(NAPL) . Organic contaminants in the NAPL state will not bind to
soil organic matter and can flow through soil pores at a relatively
fast rate. Residual NAPL can remain in the unsaturated (vadose)
zone for long periods of time due to capillary attraction.
Groundwater
Contaminants in groundwater at Harbor Island are typically
transported as either dissolved constituents or light nonaqueous
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phase liquids (floating product). A two-dimensional groundwater
transport model (FLOWPATH) along with a Digital Elevation Model was
used to determine both loading rates and concentrations of
contaminants at the shoreline. "The -->ntaniinant transport
calculations performed by the model predict the concentration of
contaminants at the discharge point to the estuary and the time for
the concentration of a contaminant to exceed a reference standard
at the island-estuary interface.
On the basis of transport modeling, only floating petroleum product
and benzene dissolved in the groundwater near the shoreline may
exceed surface water quality standards at the shoreline within the
next 50 years. All other contaminants currently in the groundwater
across the island will take more than 50 years to reach the
shoreline at levels exceeding these standards. The loading model
estimates that groundwater transport to estuarine sediment .and
water is not likely to be significant for most contaminants,
especially when compared to loading from surface water runoff and
storm drains on Harbor Island.
SUMMARY OF SITE RISKS
An assessment of the human health risk at Harbor Island was
completed according to EPA Region 10 risk assessment guidelines.
The results of a habitat evaluation indicated that Harbor Island is
unable to sustain a wildlife population or support a funcitoning
wildlife habitat due to widespread industrial development.
Therefore, an ecological risk assessment was not performed due to
the absence of wildlife habitat areas on Harbor Island. An
ecological risk assessment will be conducted for the marine
sediment operable unit of this island. The human health risk
assessment at Harbor Island involved analyte screening and
evaluation, exposure assessment, toxicity assessment, lead
biokinetics modeling and risk characterization.
People who may incidentally ingest soil through hand-to-mouth
contact and absorb contaminants through dermal contact with
contaminated soil were identified as the population most at risk of
adverse health effects. Inhalation is not a significant pathway of
exposure to contaminants on Harbor Island based on the results of
air dispersion modeling conducted during the remedial
investigation. The noncancer hazard from inhalation was not
significant (hazard index of less than one), and the cancer risk
was approximately two orders of magnitude less than that observed
for the ingestion pathway for all scenarios evaluated.
Exposure to contaminants in groundwater was not evaluated because
there is no current or foreseeable use of groundwater for drinking
water purposes, and the entire island is serviced by the city of
Seattle water system. Also, the majority of groundwater beneath
Harbor Island is naturally brackish and unsuitable for'drinking.
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Contaminants of Concern
A multiple-step screening approach was used to identify the
analytes of concern for the human health risk assessment. To be
included in the risk assessment, cc ntaminants had to occur in at
least 5% of the samples and had to be at a concentration high
enough to have a risk greater than 10~6 or hazard index of 0.1
As a result of this screening process, forty one contaminants were
identified for evaluation at Harbor Island. These included
tetrachloroethane, 2,4-dinitrotoluene, 3,3'-dichlorobenzidine,
bis(2-ethylhexyl)phthalate, carbazole, pentachlorophenol, eight
polynuclear aromatic hydrocarbons (2-methylnaphthalene,
benz(a)anthracene, chrysene, benzo(b)fluoranthene,
benzo(k)fluoranthene, benz(a)pyrene, indeno(l,2,3-cd)pyrene, and
dibenz(a,h)anthracene), four PCB mixtures (aroclors 1242, 1248,
1254, and 1260), six pesticides or pesticide breakdown products
(alpha-BHC, aldrin, dieldrin, 4,4'-ODD, 4,4'-DDE, 4,4'-DDT), and
seventeen metals (antimony, arsenic, barium,, beryllium, cadmium,.
chromium, cobalt, copper, lead, manganese, molybdenum, mercury,
nickel, thallium, tin, vanadium, and zinc). Of these, antimony,
arsenic, lead, carcinogenic PAHs and PCBs are considered the
contaminants of concern because of their higher concentrations and
toxicity compared to other contaminants. The maximum soil
concentrations of these contaminants (the concentrations which
resulted in the highest risk estimates) are shown in Table 2.
Table 2— Maximum Surface Soil Contaminant Concentrations
Contaminant Ma?:z~'":n Concentration (lag/kg)
Antimony 3,640
Arsenic 1,830
Lead 401,000
Benz(a)anthracene 37
Chrysene 49
Benzo(b)fluoranthene 39
Benzo(k)fluoranthene 39
Benz(a)pyrene 18
Indeno(l,2,3-cd)pyrene 10.6
Dibenz(a,h)anthracene 2.9
Aroclor-1242 2.1
Aroclor-1248 4.3
Aroclor-1254 360
Aroclor-1260 420
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Exposure Assessment
Harbor Island has been used for industrial purposes for
approximately the last 80 years. Currently, there are no homes,
residential areas, or commercial daycare facilities on Harbor
Island. For these reasons, both current and future industrial
exposure scenarios were evaluated. However, because Harbor Island
is currently zoned as "industrial/commercial," a commercial
scenario (daycare center) was also evaluated as a plausible future
use of the island.
Risk was calculated for the resonable maximum exposure (RME) and
for.an average exposure. The risks cited in this document are for
RME. The risks for the average exposure can be found in the
Baseline Human Health Risk Assessment. RME is equal to the upper
95% confidence limit of the concentration distribution for each
contaminant. For incidental soil ingestion and dermal contact
exposures, measured soil concentrations were used to determine the
RME values. RME values for inhalation exposures were estimated
using the results of air dispersion modeling. The exposure
assumptions used for all three pathways are based on EPA Region 10
risk assessment guidelines and are specified in the Baseline Human
Health Risk Assessment.
Due to uncertainty on the appropriate toxicity criteria to use for
evaluating lead, this metal was not included in cancer and
noncancer risk calculations, but was evaluated using the uptake
biokinetics model.
Industrial Exposures
RME values were determined at every surface soil sampling location
on Harbor Island. In calculating risk from hypothetical industrial
exposures it was assumed that risks from incidental soil ingestion,
dermal absorption, and inhalation were additive and contributed to
the total body burden. Combining all of the exposure assumptions,
summary intake factors (rates of ingestion, absorption and
inhalation) were derived for each exposure pathway. These factors
are shown in Table 3.
Table 3— Summary of Intake Factors for Industrial Exposure Pathways
Noncarcinogenic
Summary Intake Factor
Carcinogenic Summary
Intake Factor
Incidental Soil
Ingestion
4.89E-07
1.75E-07
Dermal Absorption
1.86E-05
6.64E-06
Inhalation of Paniculate
and Vapors
1.96E-01
6.98E-02
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commercial Exposures
In the commercial scenario it was assumed that infants would be
exposed to airborne contaminants for ore year (age 0-1) and tha;
children would be exposed to contaminants in air and soil for five
years (age 1-6). Reasonable maximum exposure was determined at
every surface soil sampling location on Harbor Island. As with
industrial exposures, it was assumed that doses from incidental
soil ingestion, dermal absorption, and inhalation (both infant and
child) were additive for cancer risk and contributed to the total
body burden. For noncancer health effects, child exposure pathways
were summed to estimate the total dose to a child and the infant
inhalation pathway was used to estimate total dose to an infant.
Other key exposure assumptions used for the soil ingestion, dermal
absorption, and inhalation pathways are based EPA Region X risk
assessment guidelines. Combining all of the exposure assumptions,
summary intake factors for each exposure pathway were derived for
the child, and for the inhalation pathway for the infant. These
factors are shown in Table 4.
Table 4— Summary Intake Factors for Commercial Exposure Pathways
Noncarcinogenic
Summary Intake
Factor
Carcinogenic
Summary Intake
Factor
Incidental Soil
Ingestion (Child)
9.13E-06
6.52E-07
Dermal
Absorption (Child)
9.57E-05
6.83E-06
Inhalation of
(Infant)
4.57E-02
6.52E-04
Paniculate and Vapors
(Child)
4.57D-01
3.26E-02
Toxicity Assessment
In order of priority, the following EPA sources were consulted for
toxicity criteria: Integrated Risk Information System (IRIS);
Health Effects Assessment Summary Tables (HEAST); and EPA's
Environmental Criteria and Assessment Office (ECAO). The basis for
the noncarcinogenic and carcinogenic toxicity criteria used to
calculate risk for the contaminants of concern is briefly discussed
below.
The toxicity criteria used to evaluate noncancer risks are
reference doses (RfDs). The term RfD refers to a daily intake of
a contaminant to which an individual, including sensitive
subpopulations, can be exposed without any expectation of
noncarcinogenic adverse health effects (e.g., organ damage,
biochemical alterations, birth defects).
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The contaminants of concern for noncancer health effects were
arsenic and antimony. These contaminants were only of concern
through the oral route. The oral reference dose for arsenic (3.0E-
fM for both chronic and subchronic c.rposures) is based on a study
in which skin effects were noted in humans following arsenic
ingest ion. The oral reference dose for antimony (4.0E-04 for both
chronic and subchronic exposures) is based on a study in which
blood chemistry changes were noted in rats following antimony
ingestion.
The toxicity criteria used to evaluate cancer risks are cancer
slope factors. A cancer slope factor is a numerical estimate of
the potency of a contaminant that, when multiplied by the average
lifetime dose, gives the probability of an individual developing
cancer over a lifetime. In developing cancer slope factors, it is
assumed by the EPA that any dose of a carcinogen, no matter how
small, is capable of causing cancer. Slope factors are derived by
EPA using a linearized multistage model and reflect the upper-bound
limit of a contaminant's cancer potency.
The contaminants of concern for cancer health effects were arsenic,
PAHs, and PCBs. Because these contaminants were only of concern
through oral and dermal routes, only slope factors for these
exposure routes are discussed.
EPA uses a weight-of-evidence system to convey how likely a
chemical is to be a human carcinogen, based on epidemiological
studies, animal studies, and other supportive data. The
classification scheme for characterization of weight-of-evidence
for carcinogenicity includes: Group A-known human carcinogen, Group
B-probable human carcinogen, Group C-possible human carcinogen,
Group D-not classifiable as to human carcingenicity, and Group E-
evidence of non-carcinogenicity in humans.
Arsenic is classified by EPA as a known human carcinogen (Group A) .
The oral slope factor for arsenic obtained from IRIS was 1.8
(mg/kg-day)'1. Carcinogenic PAHs are classified by EPA as probable
human carcinogens (Group B). The oral slope factor (also used as
the dermal slope factor) obtained from the EPA ECAO was 5.8 (mg/kg-
day)"1. This is the slope factor for benzo(a)pyrene. In
evaluating risk for other carcinogenic PAHs, this slope factor was
used in conjunction with a toxic equivalency factor (TEF) approach.
Using the TEF approach, the slope factor for benzo(a)pyrene was
multiplied by a numeric factor to adjust for the differing
toxicities of the carcinogenic PAHs. PCBs are also classified by
EPA as probable human carcinogens (Group B) . The oral slope factor
(also used as the dermal slope factor) obtained from IRIS was 7.7
(mg/kg-day)'1.
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Risk Characterization
Noncarcinogenic risks were evaluated by comparing contaminant daily
intakes to reference doses (RfDs) . This wa^ accomplished, by
calculating hazard quotients and hazard indices. A hazard quotient
for a particular contaminant through a given exposure route is the
ratio between the estimated daily intake and the applicable RfD.
A hazard index is a sum of hazard quotients,_which may be summed
for all contaminants for a given exposure' pathway, and across
pathways. If a hazard quotient or hazard index exceeds 1.0, it
indicates that potential noncarcinogenic health effects may occur
under the defined exposure conditions.
For all three scenarios evaluated (industrial current, industrial
future, and commercial future) hazard indices greater than one were
determined for the incidental soil ingestion pathway only. In all
three scenarios, the contaminants contributing the majority of
noncancer risk at most sample locations were arsenic and antimony.
Results show that for the current and future industrial scenarios,
less than one percent of the sample location have a hazard index
greater than one. For the commercial scenario, approximately 39
percent of the sample locations have a hazard index greater than
one. Results for each pathway and scenario are shown in Table 5.
Carcinogenic risk was calculated for each carcinogen by multiplying
the estimated daily intake of carcinogen by the appropriate cancer
slope factor. Carcinogenic risk was calculated for each carcinogen
through each exposure pathway for each individual. The total
carcinogenic risk for each scenario was calculated by summing
carcinogenic risk across exposure pathways for the industrial
(current) and the industrial (future) scenarios, and across
exposure pathways and age groups (i.e., infant + child) for the
commercial scenario.
According to the National Contingency Plan, the acceptable risk
range for carcinogens at a Superfund site is between 1 in 1,000,000
(10"6) and 1 in 10,000 (10"*). The excess lifetime cancer risk from
reasonable maximum exposure to arsenic, PAHs, and PCBs ranges from
less than 10"8 to 10~3 for both the current and future industrial
scenarios. For both scenarios, the total carcinogenic risks were
greater than 10"* at only 2% of the sample locations.
The cancer risks range from less than 10~8 to 3 x 10"3 for children
attending a daycare center (commercial scenario), if such a
facility is established on Harbor Island in the future. For this
scenario, the total carcinogenic risk was greater than 10"* at 11%
of the sample locations. For both the industrial and commercial
scenarios, the majority of the carcinogenic risk was due to
incidental ingestion of soil containing arsenic, PAHs, and PCBs.
Results of cancer risk calculations are shown in Table 6.
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Tablf 5 Summary of Noncancer Risk Calculations
Scenario
Industria(Current)
Industria(Future)
Commercial(Child)
Range of Hazard Indices for the Following Pathways:
Inhalation Ingestion
1.0
<0.00001 -3.9
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The biokinetic uptake model was use to determine appropriate
cleanup levels for lead. This model estimates total blood lead
levels in a child, resulting from exposure through routes which are
both related to conditions at Harbor Island (such as incidental
soil ingestion and inhalation-based on soil concentrations on
Harbor Island), and routes which are general for a child living in
the Seattle area (such as fruit/vegetable ingestion-based on
regional lead levels in produce). Using this model, the range of
acceptable soil lead concentrations was from 500-550 mg/kg for the
commercial daycare scenario.
Uncertainty
The accuracy of the risk estimates depends in large part on the
accuracy and representativeness of the sampling data, exposure
assumptions, and toxicity criteria. Most assumptions are
intentionally conservative so the risk estimates will be more
likely to overestimate than underestimate.
Uncertainties in sampling data directly influence the final risk
calculations. All analytical results have variability associated
with them. A variability of minus 50 to plus 100% is typical for
samples containing analytes at concentrations less than the
contract-required quantitation limit. For samples containing
higher levels of analytes, relative percent differences of 35% for
soil are considered acceptable. Depending on the actual
concentration of the analyte at these points, the reported value
may either over- or underestimate the actual concentration. In
addition to this uncertainty, the lack of PAH sampling in the tank
farm areas on Harbor Island likely resulted in an underestimate of
carcinogenic risk in these areas.
Another source of uncertainty in the risk assessment is the
assumptions used to arrive at exposure doses. A number of
assumptions were made in the risk assessment that overestimate
exposure in areas where the limitations in the available data
mademore specific quantitation difficult or impossible. It is
inherent in these assumptions that the actual case would clearly
result in reduced exposure and consequent risk.
A final source of uncertainty relates to the method by which
carcinogenic and noncarcinogenic toxicity criteria are developed.
Several conservative uncertainty factors are used in the
development of toxicity criteria, which in turn cause these
criteria to have an associated uncertainty spanning several orders
of magnitude. Specific to this risk assessment, two of the three
contaminants which made a significant contribution to carcinogenic
risk, PAHs and PCBs, have cancer slope factors which were derived
from animal studies, which contributes a high level of uncertainty.
With respect to noncarcinogenic effects, the contaminants found to
contribute most of the noncarcinogenic risk (arsenic and antimony)
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had associated uncertainty factors of 3 and 1000, respectively.
Based on these uncertainly factors, there is a high level of
confidence in the RfD for arsenic, but a larger uncertainty for the
RfD for antimony.
Environmental Evaluation
As the first step in the environmental evaluation, a habitat and
ecological community evaluation was performed. The results of the
habitat evaluation showed that Harbor Island consists of an
industrial matrix with a number of small and disconnected
undeveloped patches of land. Due to the industrial development on
the island, these patches do not appear sufficient in size or
quality to sustain a wildlife population or support a functioning
ecological community. The evaluation of potential ecological
receptors indicated that only those species (i.e., rats, dogs,
crows, and gulls) associated with urban areas would be expected to
temporarily reside on Harbor Island. A field investigation as well
as interviews were unable to verify the presence of any mammals on
Harbor Island. The lack of suitable habitat and ecological
receptors precluded the necessity for further environmental
evaluation.
REMEDIAL ACTION OBJECTIVES
The remedial action objectives (RAOs), and their associated
numerical cleanup goals, are intended to protect human health and
the environment by reducing risks to acceptable levels. RAOs are
based on the state and federal applicable or relevant and
appropriate requirements (ARARs) . The numerical cleanup goals are
based on criteria identified in these ARARs and on the results of
the human health risk assessment. The RAOs and cleanup goals for
Harbor Island are shown in Table 7.
For Harbor Island, the primary soil ARARs are the criteria
contained in the State of Washington Model Toxics Control Act
(MTCA). Three different MTCA methods were used to identify cleanup
goals for contaminants in soil:
1) Method "A" for industrial soil, which specifies cleanup goals
based on a risk of 10"5 from an individual carcinogen or hazard
index of 1.0 from a non-carcinogen, was applied to subsurface soil
because the potential for human exposure to the subsurface soil
would be infrequent. Method "A" for industrial soil was used for
lead in the surface and subsurface, because a risk-based
calculation method has not yet been scientifically determined for
lead.
2) The more stringent Method "C" for industrial soil, which
specifies cleanup goals based on a total risk of 10"5 from all
carcinogens or hazard index of 1.0 from all non-carcinogens, was
applied to the surface soil where the potential for human exposure
24
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Table 7— Remedial Action Objectives and Cleanup Goals
Primary Receptors
Remedial Action Ob . 3tive
Cleanup Goals"
Soil-Surface
Humans
Protect human hearth from
exposure to contaminants in
surface soil which pose a
combined risk of greater than 1 x
10'5.
Lead: 1,000 mg/kgb
Arsenic: 3.60 to 3ZJB mg/kgc
Antimony: 180 to 677° mg/kg
Carcinogenic PAHs: 0.1
PCBs: 0.18 to ^99C mg/kg
Soil—Subsurface
Humans and
Environment
Protect human health from
infrequent exposure to
contaminants in the subsurface
which pose a risk greater than
10"s for each contaminant
Prevent release of contaminants
into the groundwater where they
can be transported to the
shoreline, where marine organisms
could be exposed.
Lead: I.OOOmg/kg"
TPH(diesel): 600mg/kgd
TPH (gas): 400 mg/kgd
Cadmium: lOmg/kg1*
Chromium S00mg/kgb
Mercury: l.0mg/kgb
PAHs (carcinogenic): 20 mg/kgb
Arsenic: 200mg/kgb
Benzene: tJOmgfltga
Ethylbenzene: 200mg/kgd
Toluene: 100 mg/kgd
Xytenes: 150 mg/kgd
Groundwater
Environment
Prevent migration of contaminants
to the shoreline where marine
organisms could be exposed.
Protect human health from
consuming contaminated marine
organisms which pose a risk
greater than 1 x 10"6
Carbon Tetrachloride: 4.4pg/Le
Benzene: 71 jtg/L
Trichloroethane: 42/tg/L
Tetrachtoroethytene; 8£(ig/L
PCBs: 0.03 Mg/L
Arsenic: 36
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would be more frequent.
3) The Petroleum-Contaminated Soils Rating Matrix method (which
satisfies Method "B") was used to determine cleanup goals for
surface and subsurface soil contain•• r: te-? with petroleum produces.
Approximately 200 acres of surface soil, shown in Figure 4, exceed
the above listed cleanup goals. Of the total surface area which
exceeds cleanup goals, only 40 acres are unpaved. The total volume
of soil which exceeds these cleanup goals is approximately 900,000
cubic yards. Estimates for volumes of surface and subsurface soil
exceeding the cleanup goals are shown in Table 8.
Table 8 - Volumes of Soil Exceeding Cleanup Goals
Contaminant Type Volume of Son (bank cubic yards)
Surface Sofl (<0.5 Feet) Subsurface So3 (>0.5 Feet)
Organics
Inorganics
Organics and Inorganics
Total
58.000
33,000
21.000
112.000
416.000
267,000
71,000
754.000
For groundwater, EPA and Ecology have determined that the federal
and state drinking water standards do not apply because:
1) there is no current or foreseeable use of groundwater for
drinking water purposes, 2) the entire island is serviced by the
city of Seattle water system, and 3) surface water ARARs will apply
at the shoreline. For Harbor Island, the surface water ARARs are
the marine chronic criteria in the "Water Quality Standards for
Surface Waters of the State of Washington" and the human health
criteria.for consumption of marine organisms in the federal "Water
Quality Standards; Establishment of Numeric Criteria for Priority
Toxic Pollutants; States' Compliance Final Rule".
DESCRIPTION OF ALTERNATIVES
Eleven soil alternatives and four groundwater alternatives were
evaluated. Groundwater alternatives are presented separately after
the section on soil alternatives.
Soil Alternatives.
Alternative 1: No Action
Evaluation of a no action alternative is required in order to
provide a basis for comparison of existing conditions and risks of
potential conditions resulting from implementation of other
remedial alternatives.
26
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Figure 4
Surface Soil Exceeding 1.0E-5 Risk
or MTCA Criteria
&etow MTCA MetlwdA Lovots
Abovo MTCA Maawd A w Risk Unit el 1E-OS
• • lank Fann Area
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Major Components of the Remedial Alternative
Under the no action alternative, no additional remedial action will
be taken to. eliminate existing sou -ces of contamination or to
reduce the risks to humans or the effects on the environment. No
engineering, or .institutional, controls would be implemented. No
additional requirements under Superfund would be imposed on local
companies to inform workers of site conditions, nor would they be
required to use precautions in their daily work activities, other
than those required under existing regulations.
Treatment Component
There is no treatment component for this alternative.- Reduction in
toxicity or volume will occur only through natural processes such
as photodegradation or biodegradation. Natural biodegrdation of
some organics would occur over time due to the presence of
indigenous bacteria in the soil. However, due to uncontrollable
environmental factors and unknown biodegradation rates, the rate
and degree in reduction of organic contaminants cannot be predicted
with any level of certainty.
Containment Component
Containment is not a component of the no action alternative.
General Component
The no action alternative has no general component. There would be
no source control, management of migration or long-term monitoring
activities implemented in this alternative.
Cost and Remediation Time Frame
There are no costs associated with this alternative and the
alternative can be implemented immediately.
Physical Effects on Environment Caused by Implementation
The no action alternative would not remove contaminated soil from
Harbor Island. No remedial activities are performed. Therefore,
the risk from implementation of this alternative is minimal.
Compliance with ARARs
This alternative will not meet any ARARs (see page 81, "Compliance
with ARARs", for a complete list of ARARs which apply to all
alternatives).
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Alternative 2: Institutional Controls
Major Components of the Remedial Alternative
This alternative consists of implementing various engineering,
safety and institutional controls to protect workers on Harbor
Island from exposure to contaminated soil and groundwater. The
contaminated soil and groundwater would not be treated and would
remain a potential exposure route.
Treatment Component
This alternative does not have a treatment component. Some
reduction in toxicity or volume of organic contaminants would occur
over time through natural processes, such as biodegredation, as
described in Alternative 1.
Containment Component
This alternative does not have a containment component.
General Components
This alternative would provide some degree of protection for
workers through the use of various controls. Workers exposed to
uncovered contaminated soil in industries that involve significant
soil contact would be instructed to wear personal protective
equipment. Facility operators would be instructed to provide air
monitoring to determine if dust control measures were necessary to
protect workers during daily work activities. Dust suppression
could be implemented by spraying the site with water or covering
the areas with tarps. if dust suppression is not effective or
practical, the workers would be instructed to wear respirators.
Training and informational meetings would be held with employees
and property owners to inform them of site hazards. Safety
meetings would be held with employees instructing them on
precautions to be taken when working on the site to avoid dermal
contact or ingestion.
Controls would also be necessary for construction work on the
island. If contaminated, soil piles would need to be provided with
run-on/runoff controls such as tarps, curbing and liquid absorbing
booms. Contaminated soil from construction excavations would be
taken to a permitted off-site facility for treatment, storage or
disposal. Signs would be located around the island to warn about
underground contamination and hazards incurred by excavation in
those areas. Notices would be posted within buildings to inform
employees of hazards.
Institutional controls would also be imposed. One type of
institutional control which could be used is deed notices. Deed
29
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notices would warn future property owners of the contamination on
their property and would specify that contaminated soil excavated
in the future be properly handled and disposed of in accordance
with state and federal regulations.
Alternative 2 would be easily implemented. Reduction in risk
relies on the education of workers and property owners in addition
to the enforcement of safety regulations. Since numerous
businesses and heavy industrial activity exist across the island,
enforcement of safety regulations may be difficult. Over long
periods of time, the hazards, safety requirements, and need for
protective clothing could be forgotten;
This alternative does not treat or contain the contaminated soil.
The toxicity, mobility, and volume of the contaminated materials
can be expected to remain in the current condition for an
indefinite period of time.
Costs and Remediation Time Frame
The estimated capital costs for this alternative are $180,000.
There are no operation and maintenance costs associated with this
alternative.
The institutional controls alternative would take ten months to
implement.
Physical Effects on the Environment Caused by Implementation
The physical effects on the environment are minimal, since the
alternative incorporates no constuction.
Compliance With ARARs
This alternative would not meet any ARARs (see page 81) since no
treatment or containment would be performed. Concentrations of
organics in the groundwater may decrease through natural
attenuation; the number of years for the concentration to decrease
to cleanup goals cannot be predicted with any degree of certainty.
Alternative 3: Soil Containment
Major Components of the Remedial Action
This alternative consists of capping over areas where the
contamination exceeds surface and subsurface cleanup goals
identified in Table 7. The intent of this action would be to
minimize the transport of the contaminants by rainwater
infiltration and to prevent dermal contact or ingestion of the
contaminated soil by personnel working on site. This alternative
also includes engineering, safety, and institutional controls as
30
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described in Alternative 2.
Treatment Component
This alternative has no treatment component.
Containment Component
Approximately 420,000 square yards (about 40 acres), ~which are
currently uncovered and exceed cleanup goals, would be graded and
capped. The design of the cap would be based on the subsequent use
of each capped area. At a minimum, a 3-inch-thick asphalt cap with
a mimimum permeability of 10'5 cm/sec would be required. In heavy
industrial areas, a thicker asphalt cap or a reinforced, high-
strength concrete cap may be required to support heavy loads. Any
existing asphalt or concrete caps which are damaged would be
resurfaced. A fence and/or warning signs would be placed around
areas where capping is impractical or ineffective. Covered
surfaces would be inspected quarterly and repaired if needed.
Capping reduces the mobility of contaminants by providing a barrier
to infiltration which causes leaching of the organics and metals
and by eliminating erosion. Because caps do not destroy
contaminants, they provide no reduction in toxicity or volume.
However, a reduction in toxicity and volume may be seen over, time
due to natural biodegradation of the organics. Long-term, periodic
maintenance of the cap would be required to maintain its
effectiveness.
General Component
In preparation for capping, some areas would be regraded to enhance
surface drainage. Placement of the crushed rock sub-base would be
done in a manner that does not disrupt surface drainage. Excavation
of contaminated soil would be kept to a minimum.
Resurfacing paved areas on site with a surface treatment would be
performed, although a thorough inspection of all pavement on site
would be required to ensure that all damaged areas are located and
repaired. This would require moving heavy equipment and stockpiled
scrap materials to fully investigate pavement conditions.
Quarterly noncompliance inspections for all covered areas, as well
as periodic maintenance of damaged caps would be implemented.
Because contamination would remain on site, engineering, safety,
and institutional controls would be implemented as described in
Alternative 2.
Costs and Remediation Time Frame
The estimated present worth cost for this alternative is $15
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million. Capital costs, which include regrading and capping, are
$8.3 million. Operation and maintenance costs are $6.7 million and
include cap inspection and repair. The cost estimate provided for
this alternative, as well as the estimates ^or other alternatives
which include a cap, are based on the minimum 3-inch asphalt cap.
The identification of areas which will require a high-strength
concrete cap, and the cost of this cap, will be determined in the
remedial design phase.
Containment and associated engineering, safety, and institutional
controls would take 2 years to complete.
Physical Effects on the Environment Caused by Implementation
Minimal impacts to the environment would be associated with capping
exposed portions of the site. Areas would be graded, compacted and
paved at one time, minimizing the risk to the environment. During
wet weather, shallow ditches would be placed around work areas to
minimize runoff. This would minimize the potential for the
transport of contaminated soil into the storm drain system and into
the environment.
Compliance With ARARs.
This alternative would meet all ARARs except for the Clean Water
Act and the Washington Water Pollution Control Act which protect
surface water quality at the shoreline. These ARARs would not be
met because of remaining high levels of petroleum contamination
left in the soil and floating on the goundwater which would act as
continuing sources of contamination to the surface water. The
cleanup goals for soil would be met through capping, invoking
institutional controls, and compliance monitoring. Capping would
provide protection by isolating contaminated soil to remove human
exposure pathways. The cap would also mitigate further degradation
of groundwater by reducing infiltration of rainwater and migration
of contaminants to the groundwater. Institutional controls and
long-term monitoring would also be implemented in compliance with
MTCA.
Alternative 4: Soil Incineration/Solidification
Major Components of the Remedial Action
This alternative consists of excavating all soil contaminated above
cleanup levels with organics and inorganics, transferring the
material to an on-site treatment area, and treating it to levels at
or below cleanup standards. Soil contaminated with organics would
be incinerated, and soil contaminated with inorganics would be
solidified. Soil with both organic and inorganic contaminated
would be incinerated first and subsequently solidified. In areas
where excavation could not be implemented, warning signs and
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information and safety meetings would be implemented as described
in Alternative 2.
Treatment Component
A transportable incinerator and stabilization and solidification
processing equipment would be set up on the island. The treatment
area required to locate the incinerator, solidification equipment,
a stockpile area, mobile laboratory, and pollution control
equipment is approximately 400 feet long by 300 feet wide.
Contaminated soil would be transported to the treatment area. Soil
would be stockpiled in the treatment area in accordance with
Washington Dangerous Waste Regulations. The stockpile area would
have an impermeable bottom. Asphalt curbing would be provided to
prevent run-on/runoff.
Soil contaminated with organics would be screened prior to
incineration. Approximately 474,000 cubic yards of soil
contaminated with organics would be treated in the transportable
incinerator. A destruction and removal efficiency (ORE) of 99.9999
percent would be achieved for PCBs and a ORE of 99.99 percent would
be ahcieved for other organic contaminants. Incineration
permanently destroys organics and achieves almost total reduction
in contaminant toxicity and volume. Trial burns would be required
prior to incineration of contaminated soil to determine the
destruction efficiency and performance of air emission control
equipment. A continuous emissions monitoring system would be used
in conjunction with air pollution control equipment to regulate
emissions from the incinerator. Treated soil would be sampled for
total organic concentration to ensure that soil cleanup goals were
achieved before it was placed back in the ground.
Approximately 300,000 cubic yards of soil contaminated with
inorganics would be fed directly into the solidification process.
The soil would be solidified to stabilize the inorganics, tested
according to the TCLP leachate method, and placed in the ground if
it passes the TCLP test. Solidification tests performed on Harbor
Island soil indicates that this process may be implemented as an
effective method to immobilize inorganic contaminants.
Treatability studies were performed during the feasibility study to
quantitatively evaluate the potential success of a process option
to meet cleanup goals. Solidification testing was performed using
materials common in the cement industry and/or in common use. Lead
was used as the design controlling contaminant as an indicator of
the overall performance of the technology. The solidified samples
prepared under optimum conditions displayed a reduction in leachate
concentrations of 2 to 3 tiroes when compared to untreated soil.
Soil contaminated with both organics and inorganic contaminants,
approximately 92,000 cubic yards, would be incinerated to destroy
organic contamination and subsequently processed through a
solidification treatment system to treat inorganic contamination.
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This solidified soil would be tested according to the TCLP method
before being placed in the ground.
Containment Component
This alternative has no containment component .
General Component
Excavation would require removal of asphalt or concrete surfaces to
access the soil. The asphalt and concrete would be pressure-washed
to remove adhering soil. After all contaminated soil had been
removed, the concrete and asphalt would be taken to a construction
landfill for disposal. Contaminated soil would be removed from
under pavement and around utilities but not from under permanent
buildings. Contaminated soil would be excavated in cells and
transported via trucks to the treatment area. Soil would be
preprocessed through a screening and crushing operation prior to
incineration.
Following treatment, treated soil would be loaded onto trucks and
taken to the cell it came from to be used as backfill. Clean fill
would be brought in to return the site to the current grade, if
necessary. Excavation would be performed around underground
utilities and pipes and beneath pavement to minimize disruption of
services. Areas under buildings and major permanent structures
would not be excavated. In areas where excavation could not be
implemented, warning signs would be posted to notify workers that
training and personal protective equipment are recommended when
conducting industrial and construction activities as described in
Alternative 2. Information and safety meetings would be offered to
employees to warn them of any remaining hazards.
Dust suppression methods would be used to minimize fugitive dust
generated during remedial actions. Daily cleaning of paved roads
would be performed using vacuum sweeping. Contamination controls
(i.e., dust abatement and run-on, runoff controls) would be
provided for excavation, stockpiling, and treatment areas. A
debris washing station would be constructed near the soil screening
operation. Debris screened from the soil, in addition to asphalt
and concrete removed during excavation, would be washed.
Costs and Remediation Time Frame
The total present worth cost for this alternative is estimated at
$245 million. Capital costs, $17 million, include site
preparation, mobilization, and equipment costs and construction of
the treatment area. Operation and maintenance costs, $228 million,
include excavation of the soil, incineration, solidification, and
implementation of warning signs and information and safety
meetings.
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The time required to implement this alternative would be
approximately 130 months (10.8 years).
Physical Effects on the Environment Caused by Implementation
This alternative has activities that have the potential to impact
the environment. These activities consist of excavation,
incineration/solidification system installation and operation, soil
transport, material handling and storage and treated soil handling.
To mitigate the risks to the environment from these actions,
certain precautions and procedures would be implemented.
Implementation of this alternative would require excavation of
approximately 900,000 cubic yards of soil at numerous locations on
the island. Ditches and/or berms and tarps would be used during
excavation to eliminate contaminated runoff and protect the
environment. Control of contamination would be implemented by
setting up contamination control zones. Workers and equipment
would require decontamination before leaving the zones. Hazards
from dust and contaminated runoff from handling, storing and
screening untreated soil would be minimized by using ventilation
and dust collection systems on the soil screening and cement off-
loading equipment, by covering loads of soil as it is being moved,
by keeping the soil moist, and by storing all soil on double
contained and covered pads.
Compliance With ARARs
This alternative would meet all ARARs. Soil cleanup goals would be
met through incineration and stabilization of all soil above the
cleanup goals. Emissions generated during the remedial actions
(e.g., incineration, excavations, etc.) would be controlled to meet
Puget Sound Air Pollution Control Authority (PSAPCA) requirements.
The incinerator will also be operated in conformance with Dangerous
Waste incinerator performance standards, and will achieve the
99.9999 percent destruction removal efficiency for PCBs•to meet
TSCA incinerator requirements. Any construction activities
performed within 200 feet from the shoreline will be performed in
conformance with the Shoreline Management Act.
Alternative 5: Soil Bioremediation/Solidification
Major Components of the Remedial Action
This alternative consists of in situ bioremediation of areas
contaminated with the organic contaminants of concern, excavation
and solidification of areas contaminated with inorganics and
landfarming and solidification of areas contaminated with both
organics and inorganics. In areas where excavation could not be
implemented, warning signs and information and safety meetings
would be implemented as described in Alternative 2.
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Treatment Component
In situ bioremediation of soil would be implemented by constructing
* series of infiltration galleries in areas contaminated with
organic contaminants only. Approximately 70 independent
infiltration systems would be installed, each with its own set of
tanks, pumps, instruments and pipes. Oxygenated water and
nutrients would be pumped into the soil through the infiltration
system to enhance bacterial growth and degrade organic
contaminants. Extraction wells would be installed around the
systems to remove the infiltration solution and recycle it back to
the feed tank.
In areas which are only contaminated with organics and which are
currently covered by pavement, the pavement would be removed and
infiltration galleries would be installed. These areas would then
be repaired. Areas under buildings would be left to slowly
biodegrade under natural conditions.
Soil having both organic and inorganic contamination, and areas
where the organic contamination is limited to surface soil, would
be excavated, loaded into trucks and transferred to an area
established for landfarming. The landfarming area would be
approximately 650 feet long by 500 feet wide. Approximately 92,000
cubic yards of soil would be excavated for landfarm treatment.
Landfarming would biologically degrade the organic contaminants.
Following landfarming, the soil would be sent through a
solidification process to treat inorganic contamination.
Areas contaminated with inorganics only would be excavated,
transferred and directly treated through the solidification
process. Approximately 300,000 cubic yards of soil contaminated
with inorganics would be treated in this manner. After treatment by
landfarming or solidification, soil would be tested according to
the methods identified in alternative 4 before being returned to
the ground.
The effectiveness of in situ bioremediation to meet cleanup goals
is uncertain, as this technology has limited full scale
demonstration. Site-specific treatability studies would be
required to ensure that bioremediation would effectively degrade
site contaminants in the soil. A pilot project demonstration would
be required to confirm that soil cleanup goals could be met. In
situ bioremediation and landfarming would continue until the soil
cleanup goals were reached.
Reductions of TPH as high as 95 percent have been demonstrated
using in situ bioremediation. Significant reductions in volitile
organics and methylene chloride may also be expected, but
implementing a reduction of PCBs through bioremediation may be
difficult to achieve. Most organics may be degraded to levels below
their treatment levels within one year using landfarming. The
36
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effectiveness of landfarming PCB contaminants in soil is not
proven. Installing a landfarming operation on site may be
difficult due to the large area (approximately 3 acres) required.
Containment Component
This alternative has no containment component.
General Component
Excavation and backfill, as well as contamination control, would be
implemented as described in Alternative 4. Dust suppression
methods and contamination controls would be implemented as
described in Alternative 4. Areas which could not be excavated
would be covered by engineering, safety, and institutional controls
as described in Alternative 2.
Costs and Remediation Time Frame
The ability to effectively degrade site contaminants to levels
below cleanup goals through in situ bioremediation is unknown,
because full-scale implementation of this process is not a
demonstrated technology. The remediation time frame for in situ
bioremediation, therefore, has some uncertainty.
The total present worth cost for this alternative is $117 million.
Capital costs, $13 million, include landfarming and solidification
processing of soil and installation of infiltration systems.
Operation and maintenance costs, $104 million, include activities
associated with maintaining and operating the infiltration system,
excavation and implementation of the engineering, safety, and
institutional controls.
This alternative would take approximately 87 months (7.25 years) to
implement.
Physical Effects on the Environment Caused by Implementation
This alternative contains activities that have the potential to
impact the environment. These activities consist of excavation, in
situ bioremediation, landfarming, solidification, soil transport,
material handling and storage, and treated soil handling. Hazards
to the environment from these activities would be minimized by
imposing the precautions and procedures described in Alternative 4.
This alternative would cause minimal impacts to the environment.
Compliance With ARARs
Treatment of contaminated soil by landfarming and stabilization
would meet all ARARs. However, the degree to which soil cleanup
goals would be met using in situ bioremediation is uncertain/ since
this technology has had limited full-scale demonstration. Emissions
37
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generated during the remedial actions would be controlled to meet
PSAPCA requirements. Landfarming would be performed in conformance
with Dangerous Waste landfarming requirements. Any construction
activities performed within 200 feet from the shoreline will be
performed in conformance with the Shoreline Management Act.
Alternative 6: Solvent Extraction and Solidification
Major Components of the Remedial Alternative
In this alternative, organics in soil would be extracted by a
solvent extraction process, and inorganics would be solidified.
Mixtures (soil contaminated with organics and inorganics) would be
treated by solvent extraction followed by solidification. In areas
where excavation is impractical, engineering, safety, and
institutional controls would be implemented as in Alternative 2.
Treatment Component
Excavated soil would be transported to a treatment area
(approximately 300 feet long by 250 feet wide) which would include
a solvent extraction system and solidification process. Soil
contaminated with organics would be treated using solvent
extraction. Waste water generated from the solvent extraction
process could be treated and discharged to the POTW or used in the
solidification process. Soil contaminated with inorganics would be
treated with the solidification process as described in Alternative
4. Soil contaminated with mixtures of organics and inorganics
would be treated first in the solvent extraction process to remove
organics and subsequently with the solidification process to
stabilize the inorganics. After treatment by solvent extraction or
solidification, soil would be tested according to the methods
identified in alternative 4 before being returned to the ground.
Solvent extraction processes have been demonstrated to be effective
in laboratory scale treatability studies, but few have been
successfully demonstrated in full-scale field remedial projects.
Approximately 90 to 95 percent of organic contaminants have been
removed in treatability and prototype pilot studies. Solvents used
in the process would be regenerated and recycled. Organic
contaminants removed from the soil would be sent off-site for
incineration.or disposal in a hazardous waste facility.
Solvent extraction treatability studies using methanol and acetone
were performed during the Harbor Island feasibility study to
determine the effectiveness of removing organic contaminants from
soil. Polychlorinated biphenyls (PCBs) and PAHs were the organics
targeted for removal. These organics are the major health risks in
Harbor Island soil. The results of the solvent extraction
treatability studies indicated that acetone was a better solvent
than methanol. Approximately 96 percent of the PCBs and 84 percent
38
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of the PAHs were removed in the extraction tests. Additional
prototype testing would be needed to fully demonstrate the removal
efficiency of this process.
Construction of a treatment facility that would house the solvent
extraction unit, stabilization process, screening apparatus,
stockpiles, and mobile laboratory would require approximately two
acres. Although areas of this size are*available on Harbor Island,
permission to use an areas of this size could be difficult to
obtain.
Containment Component
This alternative has no containment component.
General Component
Alternative 6 consists of excavation and treatment of approximately
474,000 cubic yards of organic contaminated soil, 300,000 cubic
yards of inorganic contaminated soil, and 92,000 cubic yards of
organic and inorganic contaminated soil.
Excavation and backfill contamination control would be conducted as
described in Alternative 4. Dust suppression and run-on/runoff
controls would be implemented as described in Alternative 4. In
areas where excavation is impractical, engineering, safety, and
institutional controls would be implemented as described in
Alternative 2.
Costs and Remediation Time Frame
The estimated present worth cost for this alternative is $184
million. Capital costs, which include the soil treatment
equipment, are $9 million. Operation and maintenance costs are
$175 million and include excavation, treatment, and implementation
of engineering, safety, and institutional controls.
This alternative would take 175 months (14.6 years) to complete.
Physical Effects on the Environment Caused by Implementation
This alternative predominantly consists of the same activities as
Alternative 4, which are soil excavation and transport, material
handling and storage, and construction and operation of the
treatment process. Potential environmental hazards exist due
primarily to runoff containing contaminated material. Run-
on/runoff controls (i.e., stockpile pads, ditches, and tarps) would
be used to minimize the potential impact to the environment as
described in Alternative 4. Other precautionary measures would be
implemented as described in Alternative 4.
Compliance With ARARs
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This alternative would be designed and implemented to meet all.
ARARs. Soil cleanup goals would be met by solvent extraction and
stabilization of all soil above the cleanup goals. Emissions
generated during the remedial actions would be controlled to meet
PSAPCA requirements. Any construction activities performed within
200 feet from the shoreline will be performed in conformance with
the Shoreline Management Act.
Alternative 7: Soil Off-Site Treatment and Disposal
Major Components of the Remedial Action
This alternative consists of excavating areas that have soil
exceeding cleanup goals and transporting the soil to an off-site
treatment and/or disposal facility. Soil contaminated with
organics (474,000 cubic yards), inorganics (300,000 cubic yards)
and both organics and inorganics (92,000 cubic yards) would be
excavated. Areas that could not be excavated would be subject to
engineering, safety, and institutional controls as discussed in
Alternative 2. The excavated areas would subsequently be
backfilled with clean fill.
Treatment Component
Soil containing organics or mixtures of organics and inorganics
that include PCBs in excess of 50 mg/kg (approximately 2,000 cubic
yards) would be transported to an off-site incinerator for
treatment. After incineration, the soil residue would be
transported to a hazardous waste landfill for solidification, if
necessary, and disposal. Soil containing organics or mixtures of
organics and inorganics including less than 50 mg/kg PCBs
(approximately 201,000 cubic yards) would be tested by the TCLP
method to determine if it qualifies as a RCRA characteristic waste.
Any portion of the soil which is a RCRA waste would be transported
to an off-site hazardous waste disposal facility for stabilization
and disposal. Soil which is not a RCRA waste would be taken to an
approved sanitary landfill. Soil containing inorganics only
(approximately 300,000 cubic yards) would be treated in the same
manner. Soil containing only total petroleum hydrocarbons (TPH)
exceeding the cleanup goal of 200 mg/kg (363,000 cubic yards) would
be disposed in a local regulated landfill.
Containment Component
Soil exceeding cleanup goals is taken off-site for containment.
There is no on-site containment component in this alternative.
General Component
Excavation and backfilling of the soil would be performed in cells
as described in Alternative 4. Decontamination pads would be
40
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constructed at critical locations to minimize the spread of
contamination from excavation equipment and transport trucks. The
transport trucks would be decontaminated prior to leaving the
rontaminated areas to minimize the spread of contamination to other
areas of the site and to the roadways. Immediately after the soil
was excavated for off-site disposal, clean fill would be brought in
to backfill the hole. Roadways, parking lots and operational areas
would be repaved with asphalt after backfilling. Dust and organic
emission suppression would be implemented; contamination control
addressed as discussed in Alternative 4. Areas that could not be
excavated would be subject to engineering, safety, and
institutional controls as discussed in Alternative 2.
This alternative would be difficult to implement because of the
large volume of soil which must be excavated and transported off
site for disposal. Limitations of institutional controls are the
same as discussed in Alternative 2.
Costs and Remediation Time Frame
The total present worth cost for this alternative is estimated to
be $220 million. Capital costs, which include equipment purchase
for excavation and transport, are $12 million. Operation and
maintenance costs are $208 million and include excavation,
transport, and disposal expenses, fill and regrading expenses, as
well as implementation of engineering, safety, and institutional
controls. Alternative 7 would take 62 months (5.2 years) to
implement.
Physical Effects on the Environment Caused by Implementation
Activities that would occur under this alternative consist of soil
excavation, transport and backfill of excavated areas with imported
soil. Off-site disposal would require hauling the contaminated soil
to either an off-site hazardous waste landfill, an off-site
incinerator, or a local landfill permitted to accept TPH-
contaminated soil. This would require approximately 40,000 to
60,000 truck loads of material to be transported to the appropriate
facilities. The two main hazards associated with this include
vehicle accidents and spread of contamination off-site. Truck
payloads would be covered with tarps to prevent loss of material.
Environmental risks would be associated with contaminated runoff
from the excavation areas. This would be minimized by placing
ditches or berms around the work location. In addition, vehicle
accidents resulting in an overturned truck could cause a release of
contaminated soil into the environment. The adverse impacts to the
environment would depend upon the accident location and conditions.
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Compliance With ARARs
This alternative will be designed and implemented to meet all
ARARs. MTCA goals for soil would be met Jn this alternative through
removal and off-site disposal. Any construction activities
performed within 200 feet from the shoreline will be performed in
conformance with the Shoreline Management Act.
Alternatives 8 Through 11
Definition of Hot Spot Treatment Levels
Soil contaminated with TPH, lead, mercury, PCBs, and mixed
carcinogens at concentrations significantly above the cleanup goals
(Table 7) were identified as "hot spots" in the Feasibility Study.
The precise contaminant concentration which defines a hot spot was
originally called the "cleanup action level" but is now called the
"treatment level", to indicate that it is the level at which
contaminated soil will be excavated and treated in alternatives 8
through 11. For each hot spot contaminant, the selected treatment
level is based on a cost-benefit analysis or on existing regulatory
limits. The treatment levels for lead, mercury, and TPH are based
on a cost-benefit analysis which compared the cost of treating the
entire volume of soil above each contaminant concentration to the
benefit, which is the total mass of contaminant removed and
treated. The treatment levels for lead, mercury, and TPH were
selected at the point where the incremental mass of contaminant
treated was found to be disproportionate to the incremental volume
of contaminated soil. Appendix B describes in more detail the
method used for selecting the treatment levels for lead, mercury,
and TPH by this method.
The treatment level for PCBs is based on the federal Toxic
Substances Control Act (TSCA) regulation which specifies that
concentration of PCBs exceeding 50 rag/kg must either be incinerated
or disposed in a hazardous waste disposal facility. The treatment
level for mixed carcinogens is based on the exceedance of the
highest acceptable risk (1 x 10"*) for Superfund sites as specified
by the National Contingency Plan (NCP).
The treatment levels selected for the hot spots, shown in Table 9,
represent approximately 20 percent of the total contaminated soil
volume, but contain approximately 70 percent of the total volume of
contamination. Through this approach of identifying these hot
spots, the volume of soil representing the greatest threat to human
health and the environment could be treated to permanently reduce
its toxicity in a cost-effective manner. Figure 5 shows the
approximate locations of organic and inorganic hot spots on Harbor
Island.
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Table 9— Soil Hot Spot Treatment Levels
Item Surface Soil Subsurface Son
Risk > 1 x 10"4 Does not apply
PCBs > 50 mg/kg > 50 mg/kg
Lead > 10.000 mg/kg > 10.000 mg/kg
Mercury > 5 mg/kg > 5 mg/kg
TPH > 10.000 mg/kg > 10.000 mg/kg
Alternative 8A: Soil Hot Spot Solvent Extraction/Solidification
and Containment
Major Components of this Remedial Alternative
Alternative 8A consists of solvent extraction and/or solidification
of areas containing contaminant concentrations above the treatment
levels for organics and inorganics. Following hot spot removal and
treatment, the remaining areas contaminated above cleanup goals
would be capped. In areas where excavation is impractical,
engineering, safety, and institutional controls would be
implemented as discussed in Alternative 2.
Treatment Component
Approximately 94,200 cubic yards of surface and subsurface soil
contaminated with organics above the treatment levels would be
excavated and processed in an on-site solvent extraction system as
in Alternative 6. Treated organic hot spot soil would be tested for
total organic and inorganic concentrations and inorganic
contaminant leachability, according to the TCLP method, before
being returned to the soil. Soil which fails the TCLP test would be
considered a RCRA characteristic waste. This soil would have to be
solidified so that it no longer fails the TCLP test before being
returned to the ground. If soil passes the TCLP test, but contains
organics or inorganics above the cleanup goals, it would be placed
in the ground and capped. Approximately 85,000 cubic yards of
surface and subsurface soil contaminated with inorganics (lead and
mercury) above the treatment levels would be excavated and
solidified until it passes, the TCLP test, as in Alternative 6.
An on-site treatment area would be constructed as described in
Alternative 6. This alternative has the same destruction and
removal efficiencies (DREs), treatability and prototype pilot study
requirements, and limitations as Alternative 6.
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Figure 5
Soil Hot Spot Locations
Combined Organic
and Inorganic
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Containment Component
Areas where the soil exceeds the cleanup goals for TPH, lead,
arsenic, mercury, PCBs, and PAHs would still exist after hot spcL
removal. Much of this area is presently covered with existing
impermeable barriers of asphalt and concrete. The remaining areas
not covered by asphalt/concrete would be capped with a 3 inches of
asphalt for non-load-bearing surfaces. Load-bearing surfaces would
require a thicker asphalt cap or reinforced concrete cap. The area
to be capped is approximately 3.4 million square feet (40 acres).
In addition, an inspection would be performed to identify areas
where existing impermeable barriers were cracked or damaged. These
areas would be patched or sealed. The capped surfaces would be
maintained as described in Alternative 3.
General Component
Excavation and backfill would be conducted as described in
Alterative 4. All treated soil would be transported back to its
original location to be used as backfill. Dust suppression
methods, run-on/runoff controls, and contamination controls would
be implemented as described in Alternative 4. In areas where
excavation is impractical, engineering, safety, and institutional
controls would be implemented as described in Alternative 2.
Limitations of the engineering, safety, and institutional
controlsare the same as those described in Alternative 2.
Costs and Remediation Time Frame
Capital costs, which include the solidification and solvent
extraction equipment, are estimated to be $6.2 million. Operation
and maintenance costs are $76.5 million and include excavation,
treatment, maintenance of the cap, and implementation of
engineering, safety, and institutional controls.
Alternative 8A would take 57 months (4.75 years) to implement. The
total present worth cost for this alternative is estimated to be
$83.2 million.
Physical Effects on the Environment Caused by Implementation
This alternative has the same potential risks to the environment as
described in Alternative 6. However, the risk would be reduced
substantially due to confinement of the remedial activities to hot-
spots. Environmental risks would still consist of potential damage
due to contaminated runoff. However, with fewer locations being
remediated, the potential for environmental damage would be reduced
below that anticipated in Alternative 6.
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Compliance With ARARs
This alternative will be designed and implemented to meet all
ARARs. ARARs would be met by selective: treatment (extraction and
stabilization) of soil contaminated above "hot spot" treatment
levels, followed by capping the- remaining soil above cleanup goals
with long-term monitoring of the capped areas. Although
concentrations above cleanup goals for lead, arsenic, mercury,
PCBs, and TPH will remain in the unexcavated soil, capping would
protect human health and mitigate further degradation of
groundwater from infiltration. Some of the remaining organics
exceeding cleanup goals would naturally attenuate over time.
Emissions generated during the remedial actions would be controlled
to meet PSAPCA requirements. Any construction activities performed
within 200 feet from the shoreline will be performed in conformance
with the Shoreline Management Act.
Alternative 8B: Soil Organic Hot Spot Solvent
Extraction/Solidification and Containment
Major Components of the Remedial Action
Alternative 8B is similar to 8A except that only the organic hot
spots previously identified for PCBs, TPH, and risk greater than
10"*, are included. The soil volumes, associated with each treatment
level for the organic hot spots, are shown in Table 10.
Table 10— Organic 'Hot Spot" Volumes
Soil Type Volume (Bank Cubic Yards)
TPH greater than 10.000 mg/kg 91,000
PCBs greater than 50mg/kg 2,000
Mixed Carcinogens with risk greater than 10"4 1.200
Total 94,200
The organic hot spots are selected for treatment here (as well as
in alternatives 9B, 10B, and 11B) because TPH, which is associated
with all the organic hot spots, is mobile in soil and groundwater.
It could, therefore, be reasonably expected to migrate into the
groundwater, and ultimately into surface water surrounding Harbor
Island. In addition, these organic hot spots pose a significant
potential risk to human health and marine organisms because the TPH
contains carcinogens such as PAHs which bioaccumulate readily in
marine organisms and pose a potential risk to humans who consume
these organisms.
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In this alternative, approximately 94,000 cubic yards of soil with
organics above the treatment level would be excavated and processed
in an on-site solvent extraction system as in Alternative 6. Areas
contaminated above the cleanup ~o?1«? but below hot .sppts
concentrations, would be capped in place as described in
Alternative 3, rather than treated.
In areas where extraction or containment is impractical,
engineering, safety, and institutional controls would be
implemented as described in Alternative 2.
Treatment Component
Approximately 91,OOO cubic yards of soil contaminated with TPH
would be excavated and treated in an on-site solvent extraction
system as described in Alternative 6. Approximately 3,200 cubic
yards of soil contaminated with mixed organics would also be
excavated and treated in the on-site solvent extraction process.
After treatment, organic hot spot soil would be tested for total
inorganic concentrations and for leachability of inorganics, as in
alternative 8A, to determine if solidification or capping is
necessary prior to replacing the treated soil in the ground. This
alternative has the same removal efficiencies, treatability and
prototype study requirements, and limitations as Alternative 6.
Containment Component
Areas where the soil exceeds the cleanup goals for TPH, lead,
arsenic, mercury, PCBs, and PAHs would still exist after hot spot
removal. Much of this area is presently covered with existing
impermeable barriers of asphalt and concrete. The remaining areas
not covered by asphalt and concrete would be capped with asphalt.
The area to be capped would be slightly less than 40 acres.
Damaged existing surfaces would be resurfaced. All capped surfaces
would be inspected quarterly and replaced as needed. This
alternative has the same containment component limitations as
Alternative 3.
Tests conducted during the remedial investigation to determine the
adsorption of inorganics to soil showed that inorganics have a high
affinity for the soil and have a low mobility in the groundwater.
In addition, groundwater transport modeling conducted in the
feasibility study indicates that the inorganics currently in the
groundwater will take more than 50 years to reach the shoreline.
Capping, with proper long-term maintenance, is expected to further
decrease the mobility of inorganics in the hot spots by reducing
the infiltration of rainwater through these areas.
General Component
Excavation and backfill would be conducted as described in
Alternative 4. All treated soil would be transported back to its
47
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original location to be used as backfill. Dust suppression, run-
on/runoff controls, and contamination controls would be implemented
as described in Alternative 4. In areas where excavation is
impractical, engineering, safety, and insti^'-t.rmal controls would
be implemented as described in Alternative 2.
Costs and Remediation Time Frame
The total present worth cost for this alternative is $54.7 million.
Capital costs are $6.7 million and include site preparation,
mobilization, and the solvent extraction and solidification
processing equipment. Operation and maintenance costs are $48
million and include excavation, treatment, maintenance of the cap,
and implementation of engineering, safety, and institutional
controls.
Alternative 8B would take 57 (4.75 years) months to implement.
Physical Effects on the Environment Caused by Implementation
This alternative would pose the same potential risks to the
environment as described in Alternative 8A.
Compliance With ARARs
Solvent extraction/solidification of hot spots, followed by
containment of the remaining soil, would achieve all ARARs as
described in Alternative 8A.
Alternative 9A: Soil Hot Spot Off-Site Treatment/Disposal and
Containment
Major Components of the Remedial Action
This alternative consists of selective off-site disposal of areas
highly contaminated with organics and/or inorganics ("hot spots),
as defined in Alternative 8A, followed by containment of the
remaining portions of the site. Excavated soil hot spots would be
classified into types based on disposal options, as discussed in
Alternative 7. Soil contaminated with organics or mixtures of
organics and inorganics, which contain PCBs in excess of 50 rag/kg
(2,000 cubic yards), would be taken to an off-site incinerator for
treatment and disposal. Soil contaminated with TPH and inorganics
(71,000 cubic yards), and soil containing inorganics only (85,000
cubic yards) would be taken to an off-site hazardous waste disposal
facility for disposal. Soil containing only TPH above 10,000 mg/kg
(21,000 cubic yards) would be taken to a landfill that accepts TPH
contaminated soil.
In areas where excavation or containment is impractical,
engineering, safety, and institutional controls would be
48
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implemented as described in Alternative 2.
Treatment Component
Alternative 9A includes only one treatment component, the off-site
incineration of hot spots containing PCBs in excess of 50 mg/kg.
This treatment component has the same DREs as discussed in
Alternative 7.
Containment Component
As discussed in Alternative 8A, the remaining lower contaminated
areas would be capped with asphalt or concrete, and cracked or
damaged existing impermeable barriers would be patched or sealed.
The containment component of this alternative has the same
limitations as discussed in Alternative 3.
General Component
Excavation and contamination control would be performed as
described in Alternative 4. Decontamination pads would be
constructed near the areas of excavation and used to minimize the
spread of contaminated soil as in Alternative 7. Immediately after
soil was excavated, clean soil would be brought in for backfilling.
Roadways, parking lots, and other operational areas would be
repaved after backfilling was complete. The limitations to
excavation and disposal are the same as described in Alternative 7.
Where excavation is impractical, signs would be posted to inform
workers of the contamination and of appropriate safety precautions.
Employee informational and safety meetings would be held and
institutional controls implemented as described in Alternative 2,
as necessary. Limitations of the engineering, safety, and
institutional controls are the same as described in Alternative 2.
Costs and Remediation Time Frames
The total present worth cost for the alternative is $75.7 million.
Capital costs are $6.7 million and include capping expenses.
Operation and maintenance costs are $69 million and include
excavation, transport, disposal expenses, and cap maintenance and
implementation of engineering and institutional controls.
This alternative would take 54 months to implement.
Physical Effects on the Environment Caused by Implementation
In this alternative, soil hot spots are excavated and transported
off site for treatment and/or disposal. The remaining contaminated
soil is capped. This alternative presents the same short-term
risks to the environment as Alternative 7. The frequency of
occurrence of these risks is expected to be less than in
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Alternative 7 due to the large reduction in the volume of
contaminated soil that is excavated and disposed off site.
Approximately 179,000 cubic yards of soil would be excavated and
disposed under this alternativei The risks to the environment are'
due to contaminated runoff. ' These risks would be mitigated as
discussed in Alternative 4.
Compliance With ARARs
The off-site treatment disposal of soil hot spots, followed by
containment of the remaining soil above cleanup goals will be
designed and implemented to meet all ARARs. Although
concentrations above cleanup goals for lead, arsenic, mercury,
PCBs, and TPH will remain in the unexcavated soil, capping with
long-term monitoring would protect human health and mitigate
further degradation of groundwater from infiltration. Organics
exceeding cleanup goals would naturally attenuate over time.
Emissions generated during the remedial actions would be controlled
to meet PSAPCA requirements. Any construction activities performed
within 200 feet from the shoreline will be performed in conformance
with the Shoreline Management Act.
Alternative 9B: Soil Organic Hot Spot Off-Site Treatment/Disposal
and Containment
Major Components of the Remedial Action
This alternative is similar to Alternative 9A except that only the
"hot spots" contaminated with organics as defined in Alternative 8B
would be excavated for off-site disposal or treated. The remaining
portions of the site would be capped. In areas where excavation or
containment is impractical, engineering, safety, and institutional
controls would be implemented.
Treatment Component
Soil organic hot spots, as defined in Alternative 8B, would be
excavated and taken off-site for disposal. Excavated soil
contaminated with organics or mixtures of organics and inorganics,
which contain PCBs in excess of 50 mg/kg (2,000 cubic yards) would
be taken to an off-site incinerator for treatment and disposal, as
described in Alternative 7. This is the only treatment component
of Alternative 9B. This treatment component has the same removal
efficiencies as Alternative 7.
Containment Component
The hot spot areas contaminated with lead and mercury would be
capped along with the areas which exceed the cleanup goals for
other contaminants, as described in Alternative 8B. Damaged
existing surfaces would be inspected quarterly and repaired as
50
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needed. The containment component of this alternative has the same
limitations as Alternative 3.
General Components
The general components of this alternative are the same as those
described in Alternative 9A. Excavated soil which contains TPH and
PCB levels less than 50 mg/kg and soil which contains inorganics
only (71,000 cubic yards) would be taken to an off-site hazardous
waste landfill for disposal. Soil which contains TPH exceeding
10,000 mg/kg, but for which all other constituents are below MTCA
or other regulatory considerations, would be disposed in a
regulated landfill. The limitations to excavation and disposal are
the same as described in Alternative 7. Engineering, safety, and
institutional controls have the same limitations as Alternative 2.
Costs and Remediation Time Frames
The total present worth cost for the alternative is $50.7 million.
Capital costs are $6.7 million and include capping expenses.
Operation and maintenance costs are $44 million and include
excavation, transport and disposal expenses as well as cap
maintenance and implementation of engineering, safety, and
institutional controls.
This alternative would take 54 months (4.5 years) to implement.
Physical Effects on the Environment Caused by Implementation
This alternative presents the same risks to the environment as
described in Alternative 9A.
Compliance With ARARs
Compliance with all ARARs is achieved as described in Alternative
9A.
Alternative 10A: Soil Hot Spot Incineration/Solidification and
Containment
Major Components of the Remedial Alternative
This alternative consists of incineration and/or solidification of
organic and inorganic hot spots, as defined in Alternative 8A, with
containment of the remainding portions of the site contaminated
above cleanup goals. In areas where excavation is impractical,
engineering, safety and institutional controls would be
implemented.
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Treatment Component
Organic hot spots would be excavated and transported to an on-site
mobile incinerator for treatment, ar. described in Alternative 4.
.ihe treatment component of this alternative has the same
operational requirements,—trial burn requirements, and limitations
as Alternative 4. After treatment, organic hot spot soil would be
tested for total inorganic concentrations and for leachability of
inorganics, as in alternative 8A, to determine if solidification or
capping is necessary prior to replacing the treated soil in the
ground. Inorganic hot spots would be treated by an on-site
solidification process as described in Alternative "4.
Containment Component
The remaining contaminated areas not covered by an impermeable
barrier of asphalt or concrete would be capped as described in
Alternative 8A. Cracked or damaged asphalt or concrete would be
repaired or sealed. The containment component of this alternative
has the same limitations as discussed in Alternative 3.
General Component
Excavation procedures -, contamination control, dust control, and
backfill would occur as discussed in Alternative 4. Areas where
capping is impractical would be posted with signs, employees would
be informed of potential hazards, and institutional controls would
be implemented as described in Alternative^, as appropriate. This
alternative has the same limitations to engineering, safety, and
institutional controls as discussed in Alternative 2.
Costs and Remediation Time Frame
The total present worth cost for the alternative is $103 million.
Capital costs are $14 million and include site preparation,
mobilization, equipment purchase and capping expenses. Operation
and maintenance costs are $89 million and include excavation
expenses, incineration and solidification costs, cap maintenance,
and implementation of engineering, safety and institutional
controls.
This alternative would take 57 months (4.75 years) to implement.
Physical Effects on the Environment Caused by Implementation
This alternative presents the same short-term risks to the
environment as discussed in Alternative 4. Because the remedial
action is limited to "hot spots," the volume of soil treated is
reduced as compared to Alternative 4, and the frequency of
occurrence of adverse effects would be reduced accordingly.
Contaminated runoff from excavated areas and stockpiles would
present a potential risk to the environment. Runoff control
52
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measures would be implemented as discussed in Alternative 4 to
reduce or eliminate this hazard.
Compliance With ARARs
The alternative, which features the incineration/solidification of
soil hot spots followed by containment of remaining soil above
cleanup goals, will be designed and implemented to meet all ARARs.
Although concentrations above cleanup goals for lead, cadmium,
chromium, PCBs, and TPH will remain in the unexcavated soil,
capping would protect human health and mitigate further degradation
of groundwater from infiltration. Organics exceeding cleanup goals
would naturally attenuate over time. Emissions generated during
the remedial actions (e.g., incineration, excavations, etc.) would
be controlled to meet Puget Sound Air Pollution Control Authority
(PSAPCA) requirements. The incinerator will be operated in
conformance with Dangerous Waste incinerator performance standards,
and will achieve the 99.9999 percent destruction removal efficiency
for PCBs to meet TSCA incinerator requirements. Any construction
activities performed within 200 feet from the shoreline will be
performed in conformance with the Shoreline Management Act.
Alternative 1OB: Soil Organic Hot Spot Incineration/Solidification
and Containment
Major Components of the Remedial Alternative
This alternative consists of excavation and incineration and/or
solidification of organic hot spots as defined in Aternative 8B,
followed by containment of the remaining portions of the site. In
areas where excavation or containment is impractical, engineering,
safety, and institutional controls would be implemented.
Treatment Component
Soil organic hot spots would be treated in an on-site incinerator.
After treatment, organic hot spot soil would be tested for total
inorganic concentration and for leachability of inorganics, as in
alternative 8A, to determine if solidification or capping is
necessary prior to replacing the treated soil in the ground. The
treatment component of this alternative has the same operating
requirements, trial burn requirements, and limitations as
Alternative 4.
Containment Component
The hot spot areas contaminated with lead and mercury would be
capped along with the areas which exceed the cleanup goals, as
described in Alternative SB. Damaged existing surfaces overlying
contaminated soil would be repaired or replaced. Capped surfaces
would be inspected quarterly and repaired as needed. The
53
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containment component of this alternative has the same limitations
as discussed in Alternative 3.
General Components
Excavation procedures, contamination control, dust control, and
backfill would occur as discussed in Alternative 4. In areas where
excavation or containment is impractical, engineering, safety, and
institutional controls would be implemented as described in
Alternative 2. The limitations to the controls are the same as
described in Alternative 2.
Costs and Remediation Time Frame
The total present worth cost of the alternative is $67 million.
Capital costs are estimated to be $14 million and include
mobilization, site preparation, incineration and solidification
equipment. Operation and maintenance costs are estimated to be $53
million and include excavation, treatment, cap maintenance, and
implementation of engineering, safety, and institutional controls.
This alternative would take 57 months (4.75 years) to implement.
Physical Effects on the Environment Caused by Implementation
This alternative presents the same risks to the environment as
Alternative 10A.
Compliance With ARARs
Incineration and solidification of soil hot spots defined by the
modified criteria, followed by containment of the remaining soil
above cleanup goals, would achieve all ARARs as described in
Alternative 8A.
Alternative 11A: Soil Hot Spot Thermal Desorption/Solidification
and Containment
Major Components of the Remedial Alternative
This alternative consists of thermal desorption and solidification
of soil hot spots, as defined in Alternative 8A, with containment
of the remaining contamination above cleanup goals. Since thermal
desorption is not highly effective for removing PCBs from soil, hot
spots containing PCB contaminants (3,200 cubic yards) would be
excavated and treated in an off-site incinerator or disposed at a
hazardous waste landfill. In areas where excavation or containment
is impractical, engineering, safety, and industrial controls would
be implemented.
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Treatment Component
Thermal desorption is a process by which soil is heated to a
moderate temperature (usually in the range of 2OO-1,000°F) to
vaporize organic contaminants. The organics are not destroyed by
this process, but are physically separated from the soil.
Vaporized organics can then either be combusted in an afterburner
or removed in liquid form after condensation. Thermal desorption
would be a suitable technology for Harbor Island hot spots, since
the technology requires lower capital and operating costs compared
to incineration, organics are removed from solids and may be
recycled, and low treatment temperatures minimize the potential to
volatilize heavy metals. Based on literature performance data, it
is probable that thermal desorption would effectively remove TPH,
benzene, ethyIbenzene, and xylene from soil to cleanup goals.
Thermal desorption has not been proven as effective in removing
PCBs and high molecular weight PAHs from soil and therefore it is
uncertain if cleanup goals for these compounds could be achieved.
Thermal desorption treatability studies would be required to verify
removal efficiencies.
Soil TPH hot spots would be transported to an on-site thermal
desorption unit for treatment. After treatment, organic hot spot
soil would be tested for total inorganic concentration and for
leachability of inorganics, as in alternative 8A, to determine if
solidification or capping is necessary prior to replacing the
treated soil in the ground. Limitations for the solidification
process are the same as described in Alternative 4.
Soil contaminated with PCBs in excess of 50 mg/kg would be
excavated and taken off-site either for incineration or directly to
a hazardous waste disposal facility. The requirements for PCB
incineration are the same as described in Alternative 7. Soil
contaminated with PCBs less than 50 mg/kg or with heavy PAHs would
be excavated and taken to an off-site hazardous waste disposal
facility.. Imported, clean soil would be used as backfill.
Soil contaminated with inorganics only would be treated in the on-
site solidification process and returned to its original location
as backfill.
Containment Component
This alternative has the same containment component as Alternative
8A. All areas where soil exceeds cleanup goals would be capped.'
Existing and impermeable barriers would be inspected and patched or
sealed if necessary. All capped surfaces would be inspected
quarterly and repaired as required. The limitations to the
containment component are the same as Alternative 3.
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General Components
Excavation procedures, contamination control, and dust control
would occur as described in Alternative 4. Areas where capping if
impractical would be posted with signs, employees would be informed
of potential hazards, and institutional controls would be
implemented as described in Alternative 2, as appropriate. The
limitations to institutional controls are the same as described in
Alternative 2.
Costs and Remediation Time Frame
The total present worth cost for the alternative is $57.1 million.
Capital costs are $6.7 million and include thermal treatment and
solidification equipment, mobilization, site preparation, and
capping. Operation and maintenance costs are estimated to be $50.4
million and include excavation, treatment, transport, and disposal
of soil, cap maintenance, and implementation of engineering,
safety, and institutional controls.
Alternative 11A would take 57 months (4.75 years) to implement.
Physical Effects to the Environment Caused by Implementation
This alternative presents the same risks to the environment as the
other excavation, treatment, and disposal alternatives for hot
spots. Contaminated runoff from excavated areas and stockpiles
presents a potential risk to the environment. Run-on/runoff
control measures would be implemented as discussed in Alternative
4 to reduce or eliminate this hazard. Transport of contaminated
soil off site presents a potential risk to the environment. Truck
decontamination areas would be established on site to minimize or
eliminate the spread of contamination off site. Truck payloads
would be covered with tarps to prevent loss of material.
Compliance With ARARs
The alternative, which features the thermal desorption and
solidification or off-site disposal of soil hot spots followed by
containment of remaining soil above cleanup goals, will be designed
and implemented to meet all ARARs. Although concentrations above
cleanup goals for lead, arsenic, mercury, PCBs, and TPH will
remain in the unexcavated soil, capping would protect human health
and mitigate further degradation of groundwater from infiltration.
Organics exceeding cleanup goals would naturally attenuate over
time. Emissions generated during the remedial actions would be
controlled to meet PSAPCA requirements. Any construction
activities performed within 200 feet from the shoreline will be
performed in conformance with the Shoreline Management Act.
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Alternative 11B: Soil Organic Hot Spot Thermal Desozption and
Containment
Major Components of the Remedial Alternative
This alternative consists of thermal desorption and solidification
or off-site disposal of soil excavated from organic hot spots as
defined in Alternative 8B. Treatment components of this
alternative are the same as those of Alternative 11A, except that
soil contaminated only with inorganics would not be solidified, but
would be capped. The remaining contaminated areas not currently
covered by an impermeable barrier of asphalt or concrete would be
capped with asphalt. Institutional controls would be implemented.
Treatment Component
The organic hot spots would be treated the same as in Alternative
11A, although hot spot soil contaminated with inorganics only (lead
and mercury) would not be treated on site but would be capped. In
this alternative, 91,000 cubic yards of TPH contaminated soil would
be treated with thermal desorption. After treatment-, organic hot
spot soil would be tested for total inorganic concentration and for
leachability of inorganics, as in alternative 8A, to determine if
solidification or capping is necessary prior to replacing the
treated soil in the ground.
Soil contaminated with PCBs greater than 50 mg/kg would be
excavated and taken off-site either for incineration or diposed of
at a hazardous waste disposal facility. The requirements for PCB
incineration are the same as described in Alternative 7. Soil
contaminated with mixed organics with a risk greater thatn 10"*
would be excavated and taken to an off-site hazardous waste
disposal facility. Imported, clean soil would be used as backfill.
The operational requirements, treatability study requirements, and
limitations of the treatment component of this alternative are the
same as discussed in Alternative 11A.
Containment Component
This alternative has the same containment component as described in
Alternative 11A. Contaminated soil not excavated, treated and/or
disposed would be capped. The alternative has the same limitations
to the containment component as discussed in Alternative 3.
General,Components
General components of this alternative are the same as those
described in Alternative 11A. Excavation procedures, contamination
control, and dust control would occur as discussed in Alternative
4. Backfill would occur as discussed in Alternative 11B. This
alternative has the same limitations to the engineering, safety and
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institutional controls as Alternative 2.
Costs and Remediation Time Frame
The total present worth cost for this alternative is approximately
$38.,6 million. Capital-costs—are-$6.7- mil~l~ion, and operation and
maintenance costs are $36.9 million. The costs include the same
items outlined in Alternative 11A.
Alternative 11B would take 57 months (4.75 years) to implement.
Physical Effects on the Environment Caused by Implementation
The physical effects on the environment caused by implementation of
this alternative are the same as those discussed for Alternative
11A.
Compliance With ARARs
This alternative complies with all ARARs in the same manner as
Alternative 11A,
Description of Groundwater Alternatives
Alternative 1: No Action
Evaluation of a no action alternative is required in order to
provide a basis for comparison of existing conditions and risks of
potential conditions resulting from implementation of other
remedial alternatives.
Major Components of the Remedial Alternative
Under the no action alternative, no additional remedial action will
be taken to eliminate existing sources of contamination or to
reduce the risks to humans.
Treatment Component
There is no treatment component for this alternative. Reduction in
toxicity or volume will occur only through natural processes such
as biodegradation. Toxicity, mobility and volume of the
contaminated materials will remain at their present value for an
indefinite period of time.
Containment Component
There is no containment component for this alternative.
General Component
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In this alternative, no action is required for its implementation.
Costs and Remediation Time Frame
Since no action is taken in this alternative, no costs or time are
required for implementation.
Physical Effects on Environment Caused by Implementation
Since no action is taken in this alternative, the risk from
implementation of this alternative is minimal.
Compliance with ARARs
The no action alternative will not meet any ARARs. This
alternative is provided as a baseline to assess the effects of
leaving the site in its current state.
Alternative 2: Removal of Floating Petroleum Product and
Monitoring of Groundwater
Major Components of the Remedial Alternative
In this alternative, floating petroleum product located at Todd
Shipyard facility will be removed and treated. Groundwater in the
immediate vicinity of this floating product, which has been
contaminated with benzene and other soluable constituents of
petroluem, will be pumped and treated. Groundwater contaminant
concentrations at selected wells across Harbor Island will also be
monitored semi-annually for a period of 30 years.
Treatment Component
The floating petroleum product and the associated contaminated
groundwater, will be treated on-site by oil/water separation, air
stripping, and carbon adsorption.
Containment Component
Containment will be provided through the extraction of contaminated
water associated with the floating product.
General Components
In this alternative, floating petroleum product will be removed by
groundwater pumping. The water will then be treated by an
oil/water separator, air stripping and carbon adsorption before
discharge to the Metro POTW.
In all interior areas or the island where groundwater contaminants
concentrations exceed the cleanup goals identified in Table 7, and
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in all shoreline wells downgradient of these areas, groundwater
will be sampled and analyzed semi-annually for 30 years. The
shoreline wells will be considered the point of compliance for
achieving the cleanup goals. Groundwater quality trends wil.~. be
reviewed every 5 years to determine af reasonable progress is being
made towards achieving- the cleanup goals. If adequate progress
towards the cleanup goals is not being achieved, the need for
additional remedial actions will be evaluated.
Costs and.Remediation Time Frame
The estimated capital cost for removal of floating product,
monitoring and institutional controls is $500,000. The estimated
operations and maintenance cost is $1,100,000.
It is anticipated that removal of the petroleum product will
require 1 year for completion. Monitoring will continue for 30
years.
Physical Effects on Environment Caused by Implementation
The majority of effects on the environment caused by implementation
of this alternative are associated with the installation of the
groundwater extraction system. Human health risks could be
incurred by contact with contaminated soil during excavation.
Releases of toxic vapors could occur through excavation of soil
containing volatile organic contaminants. Some contaminants may be
emitted to the environment through the 'i«=e of the air stripper ana
other treatment units. The system will be designed to meet PSAPCA
regulations.
Compliance with ARARs
The primary ARARs are the Water Quality Standards for Surface
Water of the State of Washington (WAC 173-201A) , and the federal
surface water quality standards (40 CFR Part 131). These surface
water quality standards were adopted for the protection of marine
organisms and protection of human health from consumption of marine
organisms. With the removal of the floating product at Todd
Shipyard, and treatment of associated contaminated groundwater, the
surface water cleanup goals for organics in that area should be met
in a relatively short timeframe. Subsequent actions to be taken by
Ecology on floating product associated with the tank farms operable
unit, should allow the goals for benzene in two other areas along
the shoreline to be met over a longer timeframe through natural
biodegrdation.
This groundwater alternative, if coupled with a soil alternative
which controls sources of inorganic contamination over the entire
island, should also meet the surface water cleanup goals for
inorganics. This conclusion is supported by the results of
groundwater transport modeling, conducted during the Feasibility
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Study, which indicates that inorganics currently in the groundwater
will take more than 50 years to reach the shoreline.
This alternative should also meet all other groundwater/surface
water ARARs. These include the Washington Water Pollution Control
Act (RCW 90.48, WAC 173-201A)/Water Resources Act (RCW 90.54),
State Water Code (RCW 90.03) and Water Rights (RCW90.14), the
substantive requirements of the NPDES Program as regulated by the
State Discharge Permit Program (WAC 173-220), and the construction
and maintenance of wells (WAC 173-160). Releases of contaminants to
the air from the groundwater treatment system will also meet air
quality standards established by the Puget Sound Air Pollution
Control Authority (PSAPCA) (Regulations I,III).
Alternative 3: Precipitation/Filtration/Ion Exchange/Air
Stripping/Nitrif ication/Denitrif ication with Storm Sewer Discharge
Major Components of the Remedial Alternative
In Alternative 3, contaminated groundwater will be extracted from
three target areas along the shoreline to prevent migration of a
contaminant (benzene) to the surrounding waterways. The water will
be treated to meet surface water quality standards before discharge
to the storm sewer. Floating petroleum product at Todd Shipyards
would also be removed and treated. Groundwater contaminant
concentration across the island would also be monitored for 30
years.
Treatment Component
Alternative 3 provides treatment of groundwater at three locations
by precipitation and filtration of inorganics, air stripping of
organics, and nitrification/denitrification of ammonia. Floating
product at Todd Shipyards would also be removed and treated.
Containment Component
The goal of the groundwater extraction system is to provide
containment of a contaminant (benzene) that is expected to migrate
to the periphery of the island at concentrations which exceed
cleanup goals within 50 years.
General Components
Alternative 3 includes the removal of groundwater from three target
areas, which are located on Todd Shipyard, Shell, and Atlantic
Richfield properties. These target areas were chosen to prevent
the migration of contaminants to the periphery of the island at
concentrations which exceed cleanup goals within 50 years.
The groundwater will be extracted through wells, then pumped to a
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centrally located treatment facility. The treatment train will
include a gravity separation unit to remove floating product.
After gravity separation, a precipitation/sedimentation unit will
be used to remove the bulk of the soluble and particular
inorganics. Microfiltration and ion exchange will be subsequently
used to polish the remaining particulate and soluble inorganics,
respectively. Organics will then be removed by air stripping. A
nitrification/denitrification process will then be used to remove
ammonia before subsequent discharge to the storm sewer. Off-gases
will be treated by catalytic oxidation.
In all areas where groundwater contaminants concentrations exceed
these cleanup goals and in associated downgradient areas,
groundwater will be sampled and analyzed semi-annually for 30
years. Groundwater data trends will be reviewed every 5 years to
determine if progress towards achieving cleanup goals is being
made. If adequate progress towards cleanup goals is not being
achieved, the need for additional remedial actions will be
evaluated.
Costs and Remediation Time Frame
The estimated capital cost for the groundwater extraction and
treatment facility and for installation of the monitoring network
is $5,000,000. The estimated operation and maintenance cost for
both the treatment facility and monitoring network is $15,000,000.
Engineering, administrative, and contingency costs are include with
operation and maintenance costs. The estimated time for
groundwater treatment is 10 years. Monitoring will continue for 30
years. Monitoring may indicate that additional time or effort for
remediation is required.
Physical Effects on the Environment Caused by Implementation
Many of the effects on the environment caused by implementation of
this alternative are associated with the installation of the
groundwater extraction system and the associated piping. Human
health risks could be incurred by contact with contaminated soil
during excavation. Release of toxic vapors could occur through
excavation of soil containing volatile organic contaminants.
Some contaminants may be released to the environment through the
use of the air stripper and other treatment equipment. The effect
of this contamination will be minimized through the use of
catalytic oxidation.
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Compliance with ARARs
The primary ARARs are the Water Quality Standards for Surface
Waters of the State of Washington and the federal surface vrater
quality standards. These surface water quality standards were
adopted for the protection of marine organisms and protection of
human health from consumption of marine organisms. The groundwater
treatment and extraction system will be designed and operated to
meet the* surface water cleanup goals for soluable petroleum
constituents (primarily benzene) currently in the groundwater at
three areas along the shoreline. With the removal of the floating
product at Todd Shipyard, and subsequent actions to be taken by
Ecology on floating product associated with the tank farms, the
long term sources of soluable constituents of petroleum should also
be eliminated.
This groundwater alternative, if coupled with a soil alternative
which controls sources of inorganic contamination over the entire
island, should also meet the surface water cleanup goals for
inorganics. This conclusion is supported by the results of
groundwater transport modeling, conducted during the Feasibility
Study, which indicates that inorganics currently in the groundwater
will take more than 50 years to reach the shoreline.
This alternative should also meet all other groundwater/surface
water ARARs. These include the Washington Water Pollution Control
Act (RCW 90.48, WAC 173-201A)/Water Resources Act (RCW 90.54),
State Water Code (RCW 90.03) and Water Rights (RCW90.14), the
substantive requirements of the NPDES Program as regulated by the
State Discharge Permit Program (WAC 173'-220) , and the construction
and maintenance of wells (WAC 173-160). Releases of contaminants to
the air from the groundwater treatment system will also meet air
quality standards established by the Puget Sound Air Pollution
Control Authority (PSAPCA) (Regulations I,III).
Alternative 4: Precipitation/Filtration/Ion Exchange/UV Oxidation
with Discharge by Reinjection
Major Components of the Remedial Alternative
In this alternative, contaminated groundwater will be extracted
from the three target areas, as in alternative 3, but treated by a
different treatment technology system. In this alternative, since
the treated water will be reinjected into the ground and not
released directly to the surface water; the performance goal of the
treatment system may be slightly less stringent than that of
alternative 3. The performance goal of this treatment system will
be to reduce contaminant concentrations to levels which will not
exceed the surface water standards at the shoreline. Floating
petroleum product at Todd Shipyards would also be removed and
treated. Groundwater contaminant concentration across the island
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would also be monitored for 30 years.
Treatment Component
Alternative 4 provides treatment of groundwater at three locations
by precipitation, filtration, and ion exchange of inorganics, andJtJV
oxidation ~of orgarficsV Floating product at Todd Shipyards would
also be removed and treated.
Containment Component
The goal of the groundwater extraction system is to provide
containment of the contaminants that are expected to migrate to the
periphery of the island at concentrations which exceed the cleanup
goals within 50 years.
General Components
Alternative 4 includes the removal of groundwater from three target
areas, which are located on Todd Shipyard, Shell, and Atlantic
Richfield properties. These target areas were chosen to prevent
the migration of contaminants to the periphery of the island at
concentrations which exceed cleanup goals within 50 years.
The groundwater will be extracted through wells then pumped to a
centrally located treatment facility. The treatment train will
include a gravity separation unit to remove floating product.
After gravity separation, a precipitation/sedimentation unit will
be used to remove the bulk of the soluble and particulate
inorganics. Microfiltration and ion exchange will be subsequently
used to polish the remaining particulate and soluble inorganics,
respectively. Organics will then be removed by UV oxidation before
subsequent discharge by reinjection. Off-gases will be treated by
catalytic oxidation.
In all areas where groundwater contaminants concentrations exceed
these cleanup goals and in associated downgradient areas,
groundwater will be sampled and analyzed semi-annually for 30
years. Groundwater data trends will be reviewed every 5 years to
determine if cleanup goals are being achieved. At each 5 year
review, the need for additional remedial actions will be evaluated.
Costs and Remediation Time Frame
The estimated capital cost for the groundwater extraction and
treatment facility and for installation of the monitoring network
is $3,000,000. The estimated operation and maintenance cost for
both the treatment facility and monitoring network is $10,000,000.
Engineering, administrative, and contingency costs are include with
operation and maintenance costs. The estimated time for groundwater
treatment is 10 years. Monitoring will continue for 30 years.
Monitoring may indicate that additional time or effort for
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remediation is required.
Physical Effects on the Environment Caused by Implementation
The majority of effects on the environment caused by implementation
of this alternative are associated with the installation of the
groundwater extraction system and the associated piping. Human
health risks could be incurred by contact with contaminated soil
during excavation. Release of toxic vapors could occur through
excavation of soil containing volatile organic contaminants.
Some contaminants may be released to the environment through the
use of the air stripper and other treatment equipment. The effect
of this contamination will be minimized through the use of
catalytic oxidation.
Compliance with ARARs
The primary ARARs are the Water Quality Standards for Surface
Waters of the State of Washington and federal surface water quality
standards. These surface water quality standards were adopted for
the protection of marine organisms and protection of human health
from consumption of marine organisms. The groundwater treatment and
extraction system will be designed and operated to meet the surface
water cleanup goals for soluable petroleum constituents (primarily
benzene) currently in the groundwater at three areas along the
shoreline. With the removal of the floating product at Todd
Shipyard, and subsequent actions to be t^en by Ecology on floating
product associated with the tank farms, the long term sources of
soluable constituents of petroleum should also be eliminated.
This groundwater alternative, if coupled with a soil alternative
which controls sources of inorganic contamination over the entire
island, should also meet the surface water cleanup goals for
inorganics. This conclusion is supported by the results of
groundwater transport modeling, conducted during the Feasibility
Study, which indicates that inorganics currently in the groundwater
will take more than 50 years to reach the shoreline.
This alternative should also meet all other groundwater/surface
water ARARs. These include the Washington Water Pollution Control
Act (RCW 90.48, WAC 173-201A)/Water Resources Act (RCW 90.54),
State Water Code (RCW 90.03) and Water Rights (RCW90.14), the
substantive requirements of the NPDES Program as regulated by the
State Discharge Permit Program (WAC 173-220), and the construction
and maintenance of wells (WAC 173-160). Releases of contaminants to
the air from the groundwater treatment system will also meet air
quality standards established by the Puget Sound Air Pollution
Control Authority (PSAPCA) (Regulations I,III).
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SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The following section discusses the comparison of alternatives with
respect to the nine statutory CERCLA requirements.
Protectiveness of Human Health and the Environment
Alternatives 4, 5, 6, and 7 rank highest of all alternatives, in
terms of protection, because they either treat or remove from the
site all contaminants above the cleanup goals. Alternatives 8A, 9A,
10A, and llA are next because they treat or remove the organic and
inorganic hot spots while leaving the remaining contaminants in
place beneath an asphalt cap. Alternatives SB, 9B, 10B, and 11B are
next because they treat or remove the organic hot spots and leave
the remaining contamination beneath a cap. Alternative 3 is next
because it prevents direct human contact with contaminants but may
not prevent the migration of organic contaminants to the
surrounding surface water where marine organisms may be exposed.
Alternative 2 provides only marginal protection because direct
exposure to contaminants is still possible. Alternative 1 provides
no protection to human health or the environment.
Groundwater
Alternative 3 and 4 rank the highest because they provide
protection to the environment in the shortest timeframe through
removal of one area of floating product and treatment of
contaminated groundwater in three areas along the shoreline where
marine organisms may currently be exposed to elevated levels of
organic contaminants. Alternative 2 ranks next because it
provides protection to the environment in a longer timeframe.
Alternative 2 will achieve cleanup in a relatively short timeframe
in the most critical area of organic contamination, the floating
petroleum product at Todd Shipyard. For the two other areas of
contaminated groundwater, cleanup goals for benzene will be
achieved over a longer timeframe through a combination of source
control and natural biodegrdation. If coupled with an adequate soil
source control alternative, alternatives 2, 3, and 4, will also
protect marine organisms from exposure to elevated concentrations
of inorganics. Alternative 1 provides no protection to the
environment.
Compliance with Federal and State Applicable or Relevant and
Appropriate Regulations (ARARs)
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Alternatives 4-11 comply with all chemical-specific and action-
specific ARARs because they address all contaminated soil above tht
cleanup goals through containment, treatment, or both. Alternative
3 meets all ARARs except the state and federal surface water
quality standards. Alternatives 1 and 2 do not meet any chemical-
specific or action-specific ARARs because they do not include any
action to address soil contamination above the cleanup goals.
Groundwater
Alternatives 3 and 4 ranked highest in terms of compliance with
chemical-specific and action-specific ARARs because they achieve
compliance with surface water quality standards for organic
contaminants in the shortest timeframe. Alternative 2 ranks next
because it achieves compliance with surface water quality standards
for organic contaminants over a longer timeframe. If coupled with
a soil source control alternative, alternatives 2, 3, and 4 will
also protect marine organisms from exposure to elevated
concentrations of inorganics. Alternative 1 ranks lowest because it
does not provide any action to achieve surface water quality
standards at the shoreline.
Long-Term Effectiveness and Permanence
Soil
Alternatives 4, 5, 6, and 7 ranked highest for long-term
effectiveness and permanence because they permanently destroy or
remove all contamination in the soil exceeding cleanup goals and
require no long-term maintenance or controls. Alternatives 8A, 9A,
10A, and 11A are next best in terms of effectiveness and permanence
because they permanently destroy or remove both organic and
inorganic hot spots but would require maintenance of the capped
areas. Alternatives 8B, 9B, 10B, and 11B are next because they
permanently treat only the organic hot spots and would require
long-term maintenance of the capped areas. Alternative 3 is next
because it is effective over the long-term only if the cap is
properly maintained. Alternatives 1 and 2 do not permanently
remove health and environmental .risk and, therefore, rank lowest in
terms of long-term effectiveness and permanence.
Groundwater
If coupled with an adequate soil source control alternative,
alternatives 3 and 4 are equally ranked because they provide the
equivalent long-term effectiveness and permanence in protecting the
environment from contaminants in the groundwater. Alternative 2
ranks next because it depends more heavily on adequate source
control to achieve the cleanup goals than do alternatives 3 and 4.
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Alternative 1 ranks lowest because it provides no long-term
effectiveness.
Kaduction of Toxicity, Mobility, and Volume Through Treatment
Soil
Alternatives 4, 5, and 6 rank highest because they reduce toxicity
or mobility for all contaminated soil on the site. Alternatives 8A,
10A, and 11A rank next because they remove, destroy, or immobilize
organic and inorganic hot spot contaminants which amount to
approximately 60% of the total organic contaminants and
approximately 70% of the total inorganic contaminants. Alternatives
8B, 10B, and 11B rank next because they remove or destroy organic
hot spot contaminants and reduce the mobility of the inorganics by
capping in place. Alternatives 3, 7, 9a, and 9B all rank next
because they primarily provide reduction in mobility either by
capping contaminants in place or disposal in an off-site hazardous
waste landfill. Alternatives 1 and 2 rank lowest because they
provide no reduction in toxicity, mobility, or volume through
treatment.
Groundwater
Alternatives 3 and 4 provide the best reduction in toxicity,
mobility, and volume of contaminants in the groundwater through
extraction and treatment. Alternative 2 ranks next because it
extracts and treats floating product and associated contaminated
groundwater in the most critical area which could effect surface
water quality. Alternative 1 provides no reduction in toxicity,
mobility, or volume of contaminants through treatment.
Short Term Effectiveness
Alternative 3 ranks highest in short-term effectiveness because it
addresses site contaminants in the shortest period of time and
causes minimal additional short term risk to workers and
environment during remediation activities. Alternatives 8A, 8B,
9A, 9B, 10A, 10B, 11A and 11B all rank next in terms of short-term
risk to workers, the community, and the environment because they
require excavation and handling of comparatively moderate volumes
of contaminated soil. Alternatives 4, 5, 6, and 7 rank next because
they present a slightly higher degree of short-term risk due to the
fact that they require excavation and handling of a much larger
volume of contaminated soil and allow human exposure to this
excavated soil over a longer period of time. Alternatives 1 and 2
rank the lowest because they do not provide any protection to
human health or the environment in the short term.
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Groundwater
Alternative 2 has good short-term effectiveness because it presents
minimal exposure to humans during inplea.. r tatian and prov'.des
protection to the environment in ths short term. Alternatives 3
and 4 rank next because, even though they provide good short-term
protection to the environment, they expose workers to contamination
during well installation or during treatment facility construction
and operation. Alternative 1 ranks lowest because it provides no
protection to the environment in the short term.
Implementability
Soil
Alternatives 1, 2, and 3 are easily implemented because they
require little or no excavation, have the shortest implementation
schedules, and provide the least interruption to island businesses.
Among the alternatives which require soil treatment, the
alternatives which treat the hot spots minimize disruption of
island business because they require less excavation and have less
logistical constraints compared to alternatives that treat all
contaminated soil. Therefore, alternatives 8B, 9B, 10B, and 11B
rank next in terms of implementability because they require
excavation and treatment of only the organic hot spots.
Alternatives 8A, 9A, 10A, and 1IA rank next because they require
excavation and treatment of the organic and inorganic hot spots.
Alternatives 4, 6, and 7 rank next because they require excavation
and treatment of large quantities of soil which will cause major
disruptions to businesses on the island. Alternative 5 ranks last
due to uncertainties regarding the ability of in-situ
bioremediation to achieve cleanup goals in a reasonable timeframe,
and the requirement for a large open area needed for bioremediation
by land farming for the excavated soil.
Groundwater
Alternatives 3 and 4 may be difficult to implement' due to
difficulties in constructing the groundwater extraction and
treatment systems. Also, the extraction system may pull in brackish
water which may decrease the effectiveness of the treatment system.
Alternative 2, because it only requires removal of floating product
and a limited amount of contaminated groundwater, is more easily
implemented. Alternative 1 does not require any action and is the
easiest to implement.
Cost
Costs for all alternatives are summarized in Table 11. Alternatives
1 and 2 have the lowest costs of any soil alternatives. Alternative
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3 has the next lowest cost because it only requires containment of
the contaminated soil. The alternatives which require treatment of
hot spots have the next lowest range of costs. Among the
alternatives which require treatment of only the organic hot spcrts,
alternative 11B is the lowest. For alternatives which require
treatment of both organic and inorganic hot spots, alternative 11A
is the lowest. Alternatives 4, 5, 6, and 7, which require treatment
or disposal of all contaminated .soil, have the highest costs.
For groundwater, treatment alternatives 3 and 4 are the most
expensive. Alternatives 2 is relatively inexpensive and alternative
1 has no cost.
State Acceptance
The Department of Ecology concurs with EPA's preferred alternative,
which is identified below.
Community Acceptance
The comments received during the public comment period were
substantially in favor of the preferred alternative identified in
the Proposed Plan. A complete summary of comments received and
EPA's responses are provided in the Responsiveness Summary.
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Table 11— Present Worth Costs for Harbor Island Remedial Alternatives
I. Soil Alternatives
1 No Action None
2 Institutional Controls $150,000
3 Asphalt Cap (All Areas Above Cleanup Goals) $15.000,000
Alternatives Which Treat All Contaminants
4 Incineration/Solidification $244,700.000
5 Bioremediation/Solidification $117,400.000
6 Solvent Extraction/Solidification $184.600,000
7 Off-Site Disposal $220.000,000
Alternatives Which Treat Hot Spots and Cap Remaining Areas
8A Solvent Extraction/Solidification $83.200.000
8B Solvent Extraction (Organics Only) $54,800.000
9A Off-Site Disposal $75.400.000
9B Off-Site Disposal (Organics Only) $50,400.000
10A Incineration/Solidification $103,000,000
10B Incineration (Organics Only) $67,100 000
11A Thermal Desorption/Solidrfication '. $57,100,000
11B Thermal Desorption (Organics Only) $38,600,000
II. Groundwater Alternatives
1 No Action None
2 Petroleum Product Removal/Monitoring $1,600,000
3 Air Stripping/Monitoring $19,900,000
4 UV Oxidation/Monitoring $13,300,000
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THE SELECTED REMEDY
Major Components of the Selected Remedy
EPA's selected remedy is soil Alternative 11B combined with
_groundwater Alternative _2. --This remedy -was- selected -over- other
alternatives because it best satisfies the nine evaluation
criteria. In particular, it: is protective of human health and the
environment, meets all ARARs, has good long-term and short-term
effectiveness, reduces the toxicity and volume of the primary
threat (TPH, PCBs, and mixed organics with risk exceeding 10"*) and
reduces the mobility of the low level threat (inorganics and
organics below the treatment level), is technically and
administratively feasible to implement, has the lowest cost of all
other reasonable protective alternatives, and is acceptable to the
state and the public.
The selected remedy includes the following specific components:
Excavation and treatment of the soil containing the highest
levels of organic contamination ("hot spots"). These organic
soil hot spots are defined as Total Petroleum Hydrocarbons
(TPH) greater than 10,000 mg/kg, PCBs greater than 50 mg/kg,
and soil with mixed carcinogens with a total risk greater
than 10"*. TPH hot spot soil will be treated on site in a
thermal desbrption unit. PCBs hot spot soil will either be
sent off site for treatment (incineration) or be disposed in
a hazardous waste disposal facility. Organic hot spot soil
with risk greater than 10"* will be disposed in a hazardous
waste disposal facility.
Capping exposed contaminated soil exceeding inorganic or
organic cleanup goals. The cap would consist of a low
permeability material such as asphalt to prevent infiltration
of rainwater and reduce contaminant migration into the
environment. Existing asphalt and concrete surfaces would be
repaired to also prevent infiltration of rainwater.
Invoking institutional controls which would require long term
maintenance of new and existing caps, warn future property
owners of remaining contamination contained under capped
areas on their properties, and specify procedures for
handling and disposal of excavated contaminated soil from
beneath the capped areas if future excavation is necessary.
Removal of and treatment of floating petroleum product and
associated contaminated groundwater at Todd Shipyards to
prevent its migration into the marine environment.
Implementing groundwater monitoring for 30 years, with review
of groundwater quality trends every 5 years to assess the
effectiveness of the selected remedy.
72
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Soil organic hot spots containing concentrations of TPH exceeding
the treatment level of 10,000 mg/kg (approximately 91,000 cubic
yards) would be excavated and treated in an on-site thermal
aesorption unit. The performance goal for the thermal desorption
unit will be to achieve soil cleanup goals for TPH, benzene,
ethybenzene, toluene, and xylene (Table 7). TPH recovered from the
thermal desorption treatment will be tested to determine if it is
recyclable. If it is contaminated with other waste which prohibit
recycling, it will be disposed off-site as required by regulations
covering waste oil.
The treatment facility will consist of a soil stockpile area,
thermal desorber unit, and a mobile laboratory. This facility will
be provided with contamination control measures such as exclusion
zones, decontamination equipment and facilities, and run-on/runoff
controls. Treated organic hot spot soil would be tested for total
organic and inorganic concentrations and inorganic contaminant
leachability, according to the TCLP method, before being returned
to the soil. Soil which fails the TCLP test, would be considered a
RCRA characteristic waste. This soil would have to be solidified so
that it no longer fails the TCLP test before being returned to the
ground. If soil passes the TCLP test but contains organics or
inorganics above the cleanup goals (Table 7), this soil would be
placed in the ground and capped. TPH is not a RCRA hazardous waste
or a state dangerous waste and the treatment and disposal of TPH
contaminated soil will not have to comply with these regulations.
Organic hot spots containing concentrations of PCBs exceeding the
treatment level of 50 mg/kg (2,000 cubic yards) would be excavated
and either treated by off-site incineration or disposed at a
hazardous waste disposal facility. Soil contaminated only with PCBs
is not a RCRA hazardous waste nor a state dangerous waste but is a
TSCA waste. The remedial action for this soil meets both the TSCA
and state dangerous waste requirements. Organic hot spots
contaminated above the treatment level of risk greater than 10"*
(1,200 cubic yards) would be taken to an off-site hazardous waste
disposal facility.
The preferred alternative includes capping of lead and mercury hot
spots and all remaining contaminated soil exceeding the cleanup
goals (Table 7). Figure 6 shows areas of the island which will be
capped. The :cap will be composed of asphalt or concrete with a
minimum thickness of 3 inches and with a .minimum permeability
(hydraulic conductivity) of 10"5 cm/sec. Capping will be effective
in containing the lead and mercury in the hot spots because soil
adsorption tests conducted during the remedial investigation showed
that inorganic contaminants have a high affinity for the soil.
Capping, with proper long-term maintenance, will decrease the
migration of inorganic contaminants from the hot spots by reducing
the infiltration of rain water and the potential for migration of
73
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Figure 6
Contaminated Areas to be Capped
Combined Organic
and Inorganic
Contaminated
Areas to be Capped
-------
these contaminants into the groundwater. The results of the
Remedial Investigation show that lead in soil fails the TCLP test
at six locations and could be a RCRA characteristic waste. However,
this soil will be managed within the area of contamination (AOC)
and will receive a cap which complies with the RCRA hybrid closure
requirements.
The floating petroleum product located at the Todd Shipyards
facility would be recovered and recycled if possible. If not
recyclable, it will be disposed off-site as required by
regualations covering the disposal of waste oil. Removal of this
petroleum is critical because it is currently at the shoreline, and
is a direct source of contamination to the surface water of Elliott
Bay. The contaminated groundwater associated with this floating
product will be pumped and treated to surface water cleanup goals
before being discharged to the storm drain system.
Surface water cleanup goals will be met in an acceptable period of
time by taking source control actions which include: treatment and
off-site disposal of the organic hot spot soil which could act as
an ongoing source of contamination to surface water, removal of
floating petroleum product at Todd Shipyards, and capping the
remaining contaminated areas above the cleanup goals. These
conclusions are supported by the results of groundwater transport
modeling conducted in the feasibility study which indicate that the
inorganics currently in the groundwater will take more than 50
years to reach the shoreline under current conditions. It is
anticipated that subsequent action which may be taken by Ecology to
remediate floating product at the tank farm operable unit will
further ensure compliance with surface water cleanup goals.
In all areas where groundwater contaminant concentrations exceed
the surface water cleanup goals (which apply at the shoreline),
groundwater will be sampled semi-annually for 30 years. Groundwater
quality data trends would be reviewed every 5 years to determine if
additional remedial actions are required to meet the surface water
cleanup goals.
Basis for Remediation Goals
Soil
For Harbor Island, the primary soil ARARs are the standards
contained in the State of Washington Model Toxics Control Act
(MTCA) and its implementing regulations. Compared to subsurface
soil, surface soil presents a greater risk to human health because
of the potential for more frequent exposure through direct contact
or ingestion. Therefore, cleanup goals for the surface are more
stringent and were based on a risk calculation specified by MTCA.
The cleanup goals for soil are shown in Table 7. The objective for
75
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surface cleanup goals for carcinogens is to achieve a total cancer
risk from all carcinogens of less than one in 100,000 (10*s) .
Principle carcinogens of concern include PAHs, PCBs, and arsenic.
Cleanup goals for noncarcinogens in the surface are also based upon
the combined risk from all contaminants at each location. The
cleanup goal for noncarcinogens was to achieve contaminant
concentrations with a hazard index of less than 1.0 (one). A hazard
index of less than 1.0 means contaminant concentrations will not
pose an adverse health effect. The cleanup goal for lead, which is
considered to be a probable carcinogen, is the MTCA numerical
standard for an industrial exposure because a risk-based
calculation method for lead has not yet been scientifically
determined.
For subsurface soil, since human contact will be limited to
infrequent excavations of limited duration, MTCA numerical
standards for an industrial exposure were selected. The goal of
these numerical standards is to achieve a risk from individual
carcinogens of less than 1 in 100,000 (10~5). The MTCA numerical
standards selected for some of the contaminants in the subsurface
are also designed to protect groundwater quality.
Groundwater
EPA and Ecology have determined that the federal and state drinking
water standards do not apply to groundwater at Harbor Island. These
drinking water standards are not releva"4- and appropriate to Harloor
Island because: 1) there is no current or foreseeable use of
groundwater for drinking water purposes, 2) the entire island is
serviced by the city of Seattle water system, and 3) the surface
water quality standards (Table 7) for the protection of marine
organisms, and protection of human health from consumption of
marine organisms, will apply at the shoreline.
Groundwater contaminant transport modeling conducted in the
feasibility study demonstrated that substantially all of the
contaminants would take more than 50 years to reach the shoreline.
Only three areas along the shoreline were found to contain organic
contaminants (above the surface water standards) which are
currently at the shoreline or will be there in the next 50 years.
Protection of the Environment During Remedial Action
Engineering controls will be implemented to mitigate the impact on
the environment. During excavation, run-on/runoff controls will be
installed to keep soil from being transported into the island storm
sewer system and ultimately to Elliott Bay. Contaminated soil in
excavation areas will be covered in inclement weather to minimize
contaminated runoff. The treatment area will also be provided with
76
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run-on/runoff controls to minimize contaminant transport. Soil
stockpiles in the treatment facility area will be covered with a
rain shelter to prevent contaminated runoff.
Decontamination pads will be installed to clean equipment and
minimize the spread of contamination to other areas of the site.
Transport trucks will be covered as needed to prevent loss during
transport.
Contaminated liquid storage tanks and storage facilities will be
provided with double containment to prevent leaks from entering the
environment. Routine inspections of facilities will be performed
to assure safety measures are in place and functioning properly.
Discharges to the environment will meet applicable state and
federal regulations for protectiveness.
Cost and Remediation Time Frame
The preferred soil alternative is estimated to cost $38.6 million.
Capital costs are $6.7 million and include site preparation, health
and safety equipment, and cap placement. Operations costs are
$31.9 million and include thermal desorption operating costs,
disposal costs, soil stabilization costs, and long-term
maintenance. Soil remediation is anticipated to take 57 months to
complete.
The preferred groundwater alternative is estimated to cost $1.6
million. Capital costs of $500,000 include extraction well and
pump costs, an equalization tank, oil water separator, signage, and
monitoring well costs. Operational costs of $1.1 million include
operations and maintenance costs, monitoring well sampling and
analysis costs, and site inspections. Floating product removal is
anticipated to require 1 year. Site monitoring and inspections
will occur for 30 years.
Estimated costs for the soil and groundwater alternative are shown
in Tables 12 and 13, respectively.
77
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Table 12—Soil Remediation Alternative Costs
Description
Rcfncdidl Action fVv^c
A. General
1. Site Mobilization & Preparation
Mobilization
Temporary Construction & Security Fencing
Site Survey/Layout
Stockpile Area Preparation
2. Site Health & Safety
Decontamination Pad (30' x 60*)
Decon Operations*
DocontamuMdion Rinsate Disposal
Health & Safety Expendables (30 Personnel @
See/day/person)*
3. Field Sampling & Analyses*
On-Site Laboratory
Reid Sampling & Analysis*
Off-Site Analyses*
4. Impose Deed Restrictions
5. Install Signage
B. Soil
1. Install Asphalt Cap
Shape & Compact Designated Areas*
Place Base Course*
Place Wearing Course*
2. Removal of Existing Pavement
Asphalt/Concrete Cutting & Removal*
Decontamination Facility
Material Decontamination*
Concrete Debris Disposal (25%)*
Asphalt Recycling and Repaying*
3. Earthwork
Soil Excavation*
Excavation System (per 30' x 30' Cell)*
Hauling*
Stockpiling*
Backfill & Compact (Treated Soil)*
Backfill & Compact (Imported Soil)*
4. Thermal Desorption
Mobilization/Demobilization
Material Pretreatment Disposal*
System Operation & Maintenance*
UrH
LS
LF
Week
Each
Pad
Day
Gallon
Day
LS
Day
Sample
Property
Sign
SY
SY
SY
SY
LS
SY
SY
SY
CY
Cell
CY
CY
CY
CY
LS
CY
CY
Quantity
. 1 .
2.700
4
5
1
974
243.500
974
1
778
97
SO
30
400,000
400.000
400.000
62,900
1
62.900
15.700
62,900
95,100
286
95.100
95,100
91,000
4,100
1
455
91.000
Unit Cost
100X100.00
11.65
2.675.00
4.290.00
4.370.00
100X0
0.77
1,980.00
200,000.00
1.920.00
125XO
1.000.00
85.00
0.68
3.63
6.15
6.40
4.370.00
1.90
6.70
10.19
1.90
2.400.00
2.91
2.91
1.49
12
500.000.00
150.00
100.00
Cost
100.000
31.455
10.700
21.450
4,370
81,962
157.776
1,622339
200,000
1.2S6£91
10,203
50.000
2JSSO
228,887
1,221,850
2,070.076
338.752
4.370
100.567
88,517
539,357
152.050
577,602
232,876
232,876
119,239
41,662
500,000
57,432
7,657,600
78
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Table 17. —Soil Remediation Alternative Costs (Continued)
Description
Unit
Quantity
Unit Cost
Cost
5. Stabilization/Solidification
Mobilization/Demobilization
System Operation & Maintenance*
6. Off-Site Treatment
Hauling
Incineration
7. Off-Site Disposal (Hazardous Waste Landfill)
Hauling
Disposal
SUBTOTAL
Engineering Expenses (15%)
Contingency Allowances (25%)
TOTAL REMEDIATION COSTS (SOIL)
POST REMEDIATION MONITORING COSTS
1. Site Inspections***
2. Cap Maintenance***
SUBTOTAL
Administrative Costs (15%)
Contingency Allowances (25%)
TOTAL POST REMEDIATION COSTS (SOIL)
TOTAL PRESENT WORTH VALUE (SOIL)
LS
CY
CY
CY
CY
CY
1 100.000.00
1,200 100.00
2,000
2.000
2.100
2,100
150.00
2.550.00
50.00
150.00
100.000
100,979
300.000
5.100.000
105.500
315,000
23,649.003
Year
Year
30 6.000.00
30 413,000.00
5.912,476
33.109364
56,561
3.893,318
3,949,877
592,482
987.469
5,529,828
38.639,692
* Computed using present worth value (P/A, 10%, 2.67 years).
** Computed using present worth value (P/A, 10%, 10 years).
*** Computed using present worth value (P/A, 10%, 30 years).
79
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Table 13—Ground water Remediation Cost
Item
Floating Product Removal System
A. Equipment
4-inch Extraction Wells
Downhote Fluid Pumps
Oil/Water Separator
Equalization Tank
Oil Storage Tank
Air Stripper
Fencing
Installation
Carbon Adsorption
SUBTOTAL
Engineering (15%)
Contingency (40%)
B. Operations/Maintenance
Operations/Maintenance
Metro Discharge
TOTAL A AND B ABOVE
INSTITUTIONAL CONTROLS
C. General
1. Site Health & Safety
Decon Operations
Decontamination Rinsate Disposal
Health & Safety Expendables (4 Personnel @
See/day/person)
2. Impose Deed Restrictions
3. Install Signage
SUBTOTAL
Engineering (15%)
Contingency (25%)
TOTAL C ABOVE
D. Post Remediation Monitoring Costs
1. Groundwater Monitoring
Install Monitoring Wells
Sampling*
Laboratory Analyses*
2. Site Inspections*
SUBTOTAL
Administrative Costs (15%)
Contingency Allowances (25%)
TOTAL D ABOVE
TOTAL FOR ALTERNATIVE (ITEMS A. B, C. AND D)
Unit
ea
ea
ea
ea
ea
ea
Is
Is
ea
year
Kgal
Day
Gallon
Day
Property
Sign
Well
Year
Year
Year
Quantity
6
6
1
1
1
1
1
1
1
1
31,536
60
300
60
50
30
23
30
30
30
Unit Cost
6.000
4.000
4.500
3.750
5.000
7.750
1,000
15,000
20,000
40.000
2.56
100
0.77
264
1,000
85
2,000
43.200
32,245
6.000
Cost<$)
36.000
24,000
4.500
3,750
5,000
7,750
1,000
15.000
20,000
117,000
17.550
53320
40,000
80,732
309.102
6.000
231
15.840
50,000
2,550
74,621
11,193
18.655
• 104.469
46,000
407,243
303,971
56.561
813,775
122,066
203,444
1,137,285
1,552,856
* Computed using preseni worth value (P/A. 10%. 30 years)
80
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STATUTORY DETERMINATIONS
The selected remedy will comply with CERCLA section 121 as
follows:
Overall Protection of Human Health and the Environment
Long term protection of human health is obtained by removal and
treatment of soil hot spots containing TPH and PCBs and by capping
of all the remaining soil above cleanup goals. These actions give
a reduction in contaminant toxicity, mobility, and volume.
Following implementation of the remedy the overall risk to human
health from contaminated soil will be less than 1 x 10~S. Long term
protection of the surface water quality will ultimately be achieved
through the treatment of organic hot spots in the soil, capping of
the remaining contaminated areas, removal of the floating petroleum
product at Todd Shipyards, and natural attenuation.
Protection of human health during remediation will be obtained
through compliance with OSHA requirements, the use of personnel
protective equipment, and other safety measures and engineering
controls. Protection of the environment will be obtained during
remediation by covering stockpiles and .using berms and ditches
around excavations to control contaminated runoff. In addition,
the environment will be protected from air pollution through
compliance with the substantive requirement of the Puget Sound Air
Pollution Control Authority.
Long term monitoring and maintenance will be required for the
selected remedy. An asphalt cap has moderate permanence and
requires periodic maintenance. Island-wide groundwater monitoring
will be conducted semi-annually for 30 years after remediation.
Periodic 5 year reviews of the island-wide groundwater quality
trends will be conducted to determine if additional source control
or groundwater treatment actions are required to achieve surface
water cleanup goals at the shoreline. Removal and treatment of
floating petroleum product and associated contaminated groundwater
at Todd Shipyards will continue until surface water cleanup goals
have been achieved. If groundwater treatment at Todd Shipyards is
still ongoing at the time of the first five year review, the need
for additional soil remediation will be evaluated in consultation
with Ecology.
Compliance With ARARs
The selected alternative will meet all chemical-specific and
action-specific applicable ARARs as described below. No location-
specific ARARs have been identified for this alternative. •
81
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ARARs (Applicable)
Clean Air Act (42 U.S.C. §§ 7401 et seq.); Washington State Clean
Air Act (RCW 70.94; WAC 173-400, -460)
Remedial actions which-would-result-in major sources of emissions-,
such as soil treatment by thermal desorption, will be designed to
meet federal and state ambient air quality standards.
Puget Sound Air Pollution Control Authority (Regulations I, III)
Remedial actions which could involve releases of contaminants to
air will be performed in compliance with substantive requirements
of a permit from PSAPCA.
Washington Water Pollution Control Act (RCW 90.48); Washington
State Water Quality Standards for Surface Waters (WAC 173-201A)
The State surface water quality standards for protection of marine
organisms will be achieved over time through the treatment of
organic hot spots in soil, capping the remaining contaminated
areas, removal of the floating petroleum product at Todd Shipyards,
and natural biodegredation of remaining low level organics in the
groundwater.
State Water Pollution Control Act (RCW 90.48; WAC 173-201A)/Water •
Resources Act (RCW 90.54) .-
The determination of the known, available and reasonable
technologies (AKART) for achieving surface cleanup goals was
performed during the feasibility study. State water quality
standards will be achieved using the technology selected for
treatment of floating petroleum product and associated contaminated
groundwater.
State Water Code (RCW 90.03) and Water Rights (RCW 90.14)
These specifications for the extraction of groundwater will be met
during remedial activities. Groundwater remediation (floating
product removal and long-term monitoring) will be consistent with
beneficial uses of the resources and will not be wasteful.
Model Toxics Control Act (RCW 70.105D; WAC 173-340)
MTCA soil cleanup standards .for protection of human health in an
industrial setting and for protection of groundwater from
contaminants leaching from soil will be met through removal and
treatment of organic hot spots, and capping the remaining
contaminated areas.
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Toxic Substance Control Act (15 D.S.C. §§ 2601-2671; 40 C.F.R. Part
761.60)
This regulation requires that PCBs at concentrations exceeding 50
rag/kg be destroyed by incineration or be disposed in a hazardous
waste disposal facility.
Washington State Dangerous Waste Regulations (WAG 173-303)
This regulation may be applicable for soils contaminated with PCBs
in the concentration range of 1-50 mg/kg and for inorganics which
fail the TCLP test and are a RCRA characteristic waste.
State Minimum Standards for the construction and Maintenance of
Wells (WAC 173-160)
Standards for construction, testing, and abandonment of water and
resource protection wells will be met during the remediation and
monitoring.
Solid Waste Disposal Act, also known as the Resource Conservation
and Recovery Act, Subchapter III, (42 D.S.C. §§ 6921-6939; 40
C.F.R. Parts 261, 264, and 268)
There are no RCRA listed wastes at this site. The only RCRA
characteristic waste is soil contaminated with high concentrations
of lead which failed the TCLP leachate test conducted during the
Remedial Investigation at six locations. In the selected remedy,
this soil will be capped rather than excavated or treated because
it poses a direct contact threat, but does not pose a groundwater
threat. The three components of the cap are: 1) it prevents direct
contact with residual contamination, 2) limited long-term
maintenance of the cap and minimal groundwater monitoring is
required, and 3) institutional controls restricting land use will
be used as necessary.
The RCRA Land Disposal Restrictions (LDRs) may be applicable for
soil which is excavated and disposed off-site or treated on-site
with thermal desorption, if it fails TCLP for lead. Remedial
Investigation data indicates that none of the soil to be excavated
or treated has high enough lead concentration to fail the TCLP
test. To verify that excavated soil is not a RCRA waste, it will be
tested by the TCLP method prior to off-site disposal or after
treatment by thermal desorption. If any such soil fails TCLP, it
will be solidified such that it passes TCLP and is in compliance
with levels specified by the LDRs.
RCRA requirements for managing RCRA waste piles, storage or
treatment in tanks, and monitoring, may be applicable if any
excavated soil fails TCLP tests.
83
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ARARs (Relevant or Appropriate)
Clean Water Act (33 D.S.C. §§ 1251 et seq.; 40 C.F.R. Part 131)
The Federal surface water standards for protection of marine
organisms and human health from- ingest ion of marine organisms will
be achieved over time through removal of hot spots from both soil
and groundwater, capping, and natural biodegredation of remaining
low level organics in the groundwater.
Cost Effectiveness
The selected remedy is cost effective because costs are allocated
to remove and treat areas of the site that have the highest site
contaminant concentrations and which pose the greatest risk to the
environment and human health. The contaminants in these areas also
have the greatest potential for migration in the environment.
Areas of Harbor Island containing lower levels of contaminants
would be capped, which is protective but less costly than treatment
technologies, and appropriate given the lower site threats. The
selected remedy would treat approximately 55 percent of the total
contaminant mass, but treat only 10 percent of the contaminated
soil volume, providing a balance between cost and reduction in
toxicity and volume.
Utilization of Permanent Solutions and Resource Recovery
Technologies to the Maximum Extent Practical
The selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized in
a cost effective manner for remediation of soil and groundwater on
Harbor Island. The selected remedy provides the best balance in
terms of long-term effectiveness and permanence, reduction of
toxicity, mobility and volume achieved through treatment, short-
term effectiveness, implementability and cost, while also
considering the statutory preference for treatment as a principle
element and considering state and community acceptance.
Treatment of the organic soil hot spots and removal of the floating
product provides long-term effectiveness and permanence and
provides a significant reduction of toxicity, mobility and volume
while minimizing short-term risks. Containment of less
contaminated areas of the site also reduces the mobility and
provides long-term effectiveness, while minimizing implementation
difficulties and costs associated with removal of large and
inaccessible quantities of soil.
Alternatives which treat all contaminated soil and groundwater
provide greater reduction in toxicity, mobility and volume and
better long-term effectiveness, but cause significant short-term
84
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risks to workers, are very difficult to implement due to ongoing
facility operations, and have high costs. Alternatives which
consist of little or no treatment are more easily and quickly
implement able and have lower costs, but provide little reduction in
toxicity or volume.
This alternative meets requirements of the two mandatory threshold
criteria—protection of human health and the environment and
compliance with ARARs. The selected remedy uses a combination of
treatment, containment, and institutional controls to achieve
optimum compliance with the five balancing criteria: long-term
effectiveness, short-term effectiveness, implementability,
reduction in toxicity, mobility and volume, and cost. Reduction in
toxicity and volume and cost effectiveness were the two balancing
criteria which had the most influence on selection of the
recommended remedy.
Preference for Treatment as a Principal Element
The selected remedy treats a significant fraction of the site's
soil contamination through the use of thermal desorption. Removal
of product floating on the groundwater is accomplished using
physical extraction and separation technologies. The selected
remedy meets the statutory preference for using treatment as a
principal element by using these technologies in significant roles
in cleanup of the site.
DOCUMENTATION OF SIGNIFICANT CHANGES
The remedy selected in this Record of Decision is the preferred
alternative identified in the Proposed Plan. The only significant
differences between the preferred alternative and the selected
remedy are:
1) The preferred alternative did not specify the excavation and
off-site disposal of hot spot soil containing mixed carcinogens
with a cumlative risk exceeding 10"*. However, the treatment level
for this soil was identified in the Proposed Plan. The excavation
and disposal of this organic hot spot soil is identified as a key
element of the selected remedy in this Record of Decision.
2) The soil cleanup goals for petroleum products has been revised
to be consistent with Ecology's cleanup goals for the petroleum
tank farms at Harbor Island. These goals are: TPH (gas) = 400
mg/kg, TPH (diesel) = 600 mg/kg, Benzene = 1 mg/kg, Toluene = 100
rag/kg, Ethybenzene = 200 mg/kg, and Xylene = 150 mg/kg.
3) The preferred alternative specified incineration of soil
contaminated with PCBs at concentrations exceeding 50 mg/kg. TSCA
85
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allows either incineration or disposal in a hazardous waste
disposal facility. In the selected remedy, EPA will therefore allow
this type of soil to either be incinerated or disposed in a
hazardous waste facility.
86
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Appendix A
RESPONSIVENESS SUMMARY
FOR THE HARBOR ISLAND PSCORD OF DECISION
Overview
From 1903 to 1905, Harbor Island was created from marine
sediments dredged from the Duwamish River. Harbor Island has
been used for commercial and industrial activities including
shipping, railroad transportation, bulk fuel storage and
transfer, secondary lead smelting, lead fabrication, shipbuilding
and metal plating. Warehouses, laboratories and office buildings
have been located on the island. Approximately 70% of Harbor
Island is covered with buildings, roads or other impervious
surfaces.
The site was placed on the National Priorities List in 1983,
due to elevated lead concentrations in soil, as well as elevated
levels of other hazardous substances. The lead concentrations
were due to a lead smelter on the island, which ceased operations
in 1984.
In 1985, Department of Ecology performed an initial
investigation to define the general nature and extent of
contamination. In 1990, EPA completed Phase I of the
investigation, which focused on several suspected sources of
contamination on the island. In 1991 and 1992, EPA conducted
Phase II of the investigation.
The marine sediments and Lockheed shipyard on Harbor Island
have been designated as separate operable units. The marine
sediments proposed plan and the Lockheed shipyard proposed plan
will be issued in 1994.
On June 23, 1993, EPA began the public comment period on the
cleanup alternatives for the soil and groundwater at the Harbor
Island site. The proposed plan as well as the reports of the
investigation, were released for public comment.
The proposed plan recommended Alternative 11B for soil and
which includes removal and treatment of organic hot spots,
capping of areas exceeding defined cleanup goals for organics and
metals. The proposed plan also recommended Alternative 2 for
groundwater which includes removal and treatment of floating
petroleum product and contaminated groundwater at one location
and groundwater monitoring island-wide.
Background on Community Involvement
As described above, the proposed plan for the cleanup of the
soil and groundwater at the Harbor Island Superfund site was
-------
released on June 23, 1993. The public comment period ran from
June 23 until July 23, 1993. A request from a citizen extended
the comment period until August 23.
As part of the comment period, a public meeting was held on
July 14, 1993. 'About 50^^ people""attended"th~e~ meeting/ no one gave
public comment. Copies of the transcript are available at the
Region 10 Records office in the Park Place Building, 1200 West
6th Avenue. •
Comments received in writing are included in the following
summary. Where similar comments were received from several
commentors, the comments were lumped together and a single
response was prepared.
Responsiveness Summary
Preferred Alternative:
Comment: The Harbor Island Employers Association endorsed the
preferred alternative. The association is anxious for the
remediation to begin as quickly as possible so that normal
activities can proceed.
Response; Commented noted.
Comment: Several commentors agreed with the general elements of
the preferred alternative.
Response; Comment Noted.
Comment; The Proposed Plan calls for incineration of soil
containing PCBs over 50 ppm. TSCA specifically allows for PCB
contaminated soil at concentrations of 50 ppm or greater to be
disposed of in a chemical waste landfill. Therefore the option
of landfilling the soil should remain in order to reduce cleanup
costs.
Response; EPA agrees. The selected remedial action will now
include the option of disposal at a hazardous waste disposal
facility for soil with PCB concentrations exceeding 50 ppm.
Comment: Digging up the lead contaminated soil and hauling it
away could be more damaging than leaving it in the ground.
Response; The preferred alternative does not require excavation
•of lead contaminated soil. It will be capped in place to prevent
direct contact and migration to the surface water.
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Comment: Soils which are treated by thermal desorption to remove
TPH should only be capped if concentration of other chemicals of
concern exceed their cleanup criteria. It is unclear which soils
need to be solidified after treatmer +: by thermal desorption.
During the thermal desorption process, substantial mixing and
disturbance of the soils will also occur. Thus, prior to capping
the presence of chemical concentration exceeding the cleanup
goals should be determined. EPA should consider consolidation of
materials that require capping to increase cost-effectiveness.
Response; Soil which contains inorganic contaminants above the
cleanup goals, after removal of TPH by thermal desorption, would
have to be solidified if the concentrations of inorganics were
high enough to constitute a "characteristic" RCRA waste. To
determine if treated soil is a RCRA characteristic waste, soil
would have to be tested according to the TCLP (leachate) method
before it is replaced in the ground. If soil contains inorganics
which leach above concentrations established by RCRA regulations,
this soil would have to solidified before placing it in the
ground. If the treated soil does not leach at concentrations
high enough to make it a RCRA waste, the soil would be placed in
the ground and then capped. EPA will consider consolidation of
treated materials if the results of the remedial design indicate
that there may by an increase in cost-effectiveness.
Cleanup Goals:
Comment; Several commentors stated that EPA has improperly
applied the State of Washington's Model Toxic Control Act, Method
"A", to select cleanup goals for contaminants (particularly
petroleum) at Harbor Island. Many commentors said that Method
"C" would be more appropriate for determining cleanup goals at
this site.
Response: In the Proposed Plan, EPA applied Method "A" to lead
and Total Petroleum Hydrocarbons (TPH), for which no Method "C"
calculations exist. Method "A" was also applied to all
contaminants in the subsurface soil because of anticipated
infrequent exposure of short duration. Method "C" was applied to
all contaminants other than lead and TPH in the surface soil. As
a result of comments received from Ecology (see below), EPA has
decided to revise the cleanup goals for petroleum, based on
Ecology's Petroleum-Contaminated Soils Rating Matrix method, to
be consistent with Ecology's cleanup goals for the petroleum tank
farm operable unit. In regard to EPA's use of Method "A",
Ecology has confirmed that Method "A" is appropriate for lead in
surface soil and for all contaminants, other than petroleum, in
the subsurface.
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Comment: Ecology informed EPA that the originally selected
cleanup goal of 200 mg/kg for TPH, based on Method A, is not
appropriate for Harbor Island. Ecology has recently established
cleanup goals for petroleum contaFiran*. r for the petroleum tark
farm operable unit based on the Petroleum-Contaminated Soils
Rating- Matrix method (which satisfies MTCA Method B). Ecology has
determined that this method is appropriate for the rest of the
island. The cleanup goals using this alternate method are: TPH
(gas) = 400 mg/kg, TPH (diesel) = 600 mg/kg, Benzene = 1 mg/kg,
Toluene = 100 mg/kg, Ethybenzene = 200 mg/kg, and Xylene = 150
mg/kg.
Response; EPA will accept these new cleanup goals for the above
petroleum compounds and will eliminate the previously identified
goal of 200 mg/kg for TPH identified in the Proposed Plan. The
island-wide petroleum cleanup goals will now be consistent with
the goals established by Ecology.
Comment: The Department of Ecology expressed concern that the
method used by EPA to select cleanup action levels for'hot spot
contaminants was not justified.
Response: The objective of the cost-benefit method used to
select the hot spot cleanup action levels was to identify areas
containing high concentrations of contaminants in relatively
small volumes of soil, which could be excavated and treated with
an optimal cost-benefit. (The cleanup action levels are now
referred to as "treatment levels" in the Record of Decision.) The
cost-benefit method was used for the contaminants lead, mercury,
and TPH. Treatment levels were derived through an iterative
analysis which compared the contaminant volume to the contaminant
mass within that volume, over a range of concentrations. The
treatment level for each contaminant was then selected at the
point where the incremental mass of contaminant was found to be
disproportionate to' the incremental volume of contaminated soil.
Subsequent to performing this analysis, a more comprehensive
cost-benefit analysis was performed to verify these treatment
levels. A description of how this method was used to select"
treatment levels is provided in Appendix B.
The treatment levels for the PCBs and mixed carcinogens hot spots
were set according to regulatory limits. The treatment level for
PCBs of 50 mg/kg was set equal to the concentration regulated
under the Toxic Substance Control Act (TSCA), and the treatment
level for mixed carcinogens was set at the upper end of the
acceptable risk level (IxlO"4) specified for Superfund sites
according to the National Contigency Plan (NCP).
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Comment;: The cleanup goals for PCBs of 0.18 to 2.99 mg/kg is
unreasonably stringent. This range is significantly below the 10
mg/kg standard for industrial areas under the state of
Washington's MTCA Method A.
Response; When there is a mixture of contaminants, as occurs at
many locations on Harbor Island, MTCA Method A is not
appropriate. In such cases the appropriate method is Method C,
which requires that cumulative risk from all carcinogens at each
location not exceed 10"5. At many locations, the PCBs are
collocated with other carcinogens, such as arsenic or PAHs. To
maintain an acceptable cumulative risk level, the PCB cleanup
level must be a fraction of what it would be if it were the only
contaminant present.
Petroleum:
Comment; Materials identified at Harbor Island as petroleum fuel
products and residues are not hazardous substances as defined in
CERCLA and therefore are not subject to EPA's jurisdiction under
CERCLA.
Response; There has been some confusion about the CERCLA
petroleum exclusion provision. Under CERCLA, pure petroleum
products are not hazardous substances. However, when mixed with
other hazardous substances, it is appropriate for EPA to take
jurisdiction for cleaning up such mixtures. At Harbor Island,
EPA specifically carved out a separate petroleum tank farm
operable unit to be managed by Ecology because contamination in
this unit is derived principally from petroleum. All areas of
the island outside of the tank farm unit are not areas of purely
petroleum contamination and are therefore subject to EPA's
jurisdiction.
Comment: One commentor stated that EPA inappropriately excluded
other viable remedial alternatives from consideration for
petroleum contaminated soil. Two other alternatives specifically
identified were in-situ bioremediation and use of petroleum
contaminated soil for asphalt production.
Response: In the Feasibility Study, EPA evaluated a wide range of
treatment technologies used to remediate hazardous waste sites
and. screened out many of these technologies based on the criteria
of effectiveness, implementability and cost. Of the eleven
alternatives which received full evaluation, EPA believes that
thermal desorption best meets the nine evaluation criteria. In
particular, it is a proven technology, it can meet the cleanup
action goals,.it is the most cost-effective treatment technology
identified, and is easily implemented. In addition, the TPH
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removed from the soil can be recycled and used in other
applications, such as making asphalt. In-situ bioremediation was
evaluated in alternative 5 and was not selected because: 1) it is
not certain that cleanup action goa"s could be met without
conducting an extensive treatability study, 2) it was not as cost
effective as the selected "technology, and 3) gxoundwater
extraction, as required by this method, is not feasible at the
shoreline because it would draw in and pump out saltwater from
the surrounding surface water.
Comment; Where oil is in quantity and situated where it can be
extracted from the soil it should be pumped and recovered.
Response; The selected remedial action is consistent with the
concept of recovery because it requires that high concentrations
of petroleum in the soil (hot spots) be recovered by thermal
desorption and that floating petroleum product be pumped and
recovered. Once recovered, this petroleum may have the potential
to be used in such applications as asphalt production.
Cost:
Comment: There should be better substantiation of the estimated
costs for the alternatives which are being compared.
Response; The level of cost detail anJ the assumptions used ir.
developing the cost estimates for each alternative is adequate
for a Feasibility Study. EPA included conservative contingencies
into the cost calculations to cover additional unforeseen
expenses. However, the costs at this point are only an
engineering estimate and will be further refined during the
remedial design.
Comment: It is unclear whether the cost estimate for the
preferred alternative includes the cost to incinerate the 2,000
cubic yards of PCB-contaminated soil in an off-site commercial
incineration facility.
Response; The cost estimate for the preferred alternative does
include -the cost of off-site incineration for PCB-contaminated
soil.
Remedial Investigation/Feasibility Study:
Comment: The description of the selected alternative presented in
the feasibility study addendum indicates that soil containing
PCBs and PAHs at levels below the hot spot criteria will be
excavated and disposed off-site in a hazardous waste landfill.
6
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No such requirement is indicated in the description of the
preferred alternative in the Proposed Plan.
Response: The Proposed Plan identified organic hot spots with a
total carcinogen risk exceeding 10"*. These organic hot spots
constitute soil containing mixtures of PCBs (at concentrations
below 50 ppm) / PAHs, and arsenic. The total volume of soil
associated with these organic hot spots is approximately 1,200
cubic yards. The description of the selected alternative in the
feasibility study addendum identifies off-site disposal in a
hazardous waste landfill for this soil. Because of an oversight,
the preferred alternative in the Proposed Plan did not discuss
disposal of this hot spot soil. The Record of Decision will
identify this soil for off-rsite disposal.
Comment; Several commentors identified numerous technical errors,
discrepancies and inaccuracies in the Remedial Investigation and
Feasibility Study (RI/FS) Reports.
Response: None of the technical errors, discrepancies or
inaccuracies identified were regarded as significant by EPA and
did not change EPA's selection of the preferred alternative.
However, EPA has responded to these comments collectively in the
form of a Technical Errata Memorandum which will be attached to
the RI/FS report.
Comment; The Port of Seattle (Port) believes that the groundwater
monitoring plan should be revised to reduce the number and modify
the locations of proposed compliance monitoring wells on Port of
Seattle Terminal 18 property.
Response: The groundwater monitoring plan identified in the
Feasibility Study is intended to be a preliminary design. Final
location and number of monitoring wells will be determined during
the Remedial Design and can be negotiated between EPA and the
potentially responsible parties (PRPs) at that time, assuming
that the PRPs are implementing the remedial action for the site.
Comment; Lockheed commented that the hot spot maps should be
revised to incorporate the Phase II RI data collected at the
Lockheed Shipyard 1. This new data has reduced the area defined
as TPH hot spots on the Lockheed property by approximately 97%,
relative to the TPH hot spot area estimated by EPA in the
Feasibility Study.
Response: EPA intends to reevaluate the Phase II RI data and its
impact on the size of the TPH hot spots on the Lockheed Shipyard
facility before it issues a Proposed Plan for that facility next
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year. Since -these hot spots are substantially on the Lockheed
facility, they were not addressed in the Harbor Island Proposed
Plan and are not addressed in this Record of Decision.
Groundwater:
Comment: For the groundwater model, why were maximum
concentrations of contaminants used. Also, using the current
rate of rainfall infiltration is not reasonable since capping is
recommended as part of the soil remedial action. The selection
of groundwater treatment is based on data from only two rounds of
groundwater sampling.
Response: Maximum contaminant concentrations and current rates of
rainfall infiltration for the groundwater model were used because
these conditions are considered conservative. Since there are
uncertainties in the groundwater data collected during the
Remedial Investigation, and uncertainties in the groundwater
modeling used, EPA believes it .is prudent to be conservative so
that the environment is protected against the most sever
groundwater contamination which could reach the shoreline. The
only groundwater treatment in the selected remedy involves
pumping•and treating the floating petroleum product at Todd
Shipyards. At this location approximately 6 inches of floating
product was observed during installation of the monitoring well.
Benzene concentrations at this location for both rounds of
sampling exceeded the surface water cleanup goal by approximately
an order of magnitude. This data indicates that this area of
groundwater contamination presents a critical risk to the
environment and should be addressed immediately. After remedial
action is initiated, groundwater will be monitored island-wide
semi-annually for up to 30 years. This groundwater data will be
reviewed every five years to determine if progress towards
cleanup goals is being achieved. If adequate progress is not
being achieved at that time, additional groundwater treatment
could be required.
Comment; In the Feasibility Study, groundwater cleanup goals
(MCLs) based on drinking water standards were identified as
alternate cleanup goals for several contaminants. MCLs are not
appropriate for Harbor Island because the groundwater is not
potable.
Response: EPA agrees. The MCLs were initially identified as
alternate cleanup goals in the Feasibility Study before EPA and
Ecology decided that the drinking water standards do not apply to
the Harbor Island groundwater. In the Proposed Plan, only the
surface water standards were cited as cleanup goals at the
shoreline.
8
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Comment: Lockheed commented that "the industrial nature of the
area and the general consensus that groundwater will not be used
as a potable water supply, a much higher cleanup level for TPH,
such as 1,000 rag/kg for TPH as heavier petroleum fuel, would be
appropriate and more than adequately health protective for the
site."
Response: EPA has adopted Ecology's cleanup goals for petroleum
products based on the Petroleum Contaminated Soils Rating Matrix
method (see response above). The new cleanup goal for heavy
petroleum fuel (diesel), is now 600 rag/kg.
Comment: The Port commented that it is unable to determine
whether groundwater compliance will be based on monitoring data
which includes only metals that exceed cleanup goals in each
respective well or on all metals of concern at each well. The
Port believes it would be more appropriate to monitor all
compliance monitoring wells for all metals of potential concern,
rather than selective metals, of potential concern in order to
address trends in groundwater quality.
Response: EPA agrees. It is EPA's intent to monitor for all
metals at all compliance monitoring wells. This will be
necessary to determine trends in groundwater quality.
Comment; EPA has recommended a remedial action for soil based on
limited soil data and overestimation of volumes due to use of
Thiessen polygons.
Response: The RI/FS established preliminary estimates of
contaminated soil volumes. Additional soil sampling will be
required during the Remedial Design phase to more accurately
identify volumes of soil which must be excavated and treated or
disposed off-site.
Risk Assessment:
Comment: The risk assessment does not address background. The
low end of the cleanup goal range for arsenic is.potentially
below background levels in surface soils for this area and it is
unrealistic to clean up below background levels. EPA used an
overconservative scenario (daycare facility) to estimate
potential risk. Risk was also evaluated on a location-by-
location basis which leads to an overestimation of risk.
Response: The low end of the cleanup goal range for arsenic
occurs in locations where arsenic is collocated with other
carcinogens and the combined risks of all carcinogens present
9
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exceeds the cleanup goal of 10"5. To maintain an acceptable
cumulative risk level, the arsenic cleanup level must be a
fraction of what it would be if it were the only contaminant
present.. There are no daycare cent-rs curr ^itiy on Harbor
Island, but the island is zoned for commercial uses, which
includes daycare centers. The daycare center scenario was
conducted as a hypothetical scenario, but was not used in
establishing cleanup goals because EPA selected cleanup goals for
an industrial scenario as appropriate .for Harbor Island. EPA
does not agree that a location-by-location risk assessment
overestimates risk.
«
Potential Responsibility:
Comment: Several commentors raised the issue that they should not
be considered Potentially Responsible Parties (PRPs), even though
they were either owners of property or operators of facilities on
the site.
Response: CERCLA 107(a)(1) which makes owners and operators of a
Superfuhd site responsible parties is a strict liability statute.
Fault is not a relevant consideration in assessing liability
under any strict liability statute. Contribution or relative
responsibility among PRPs is relevant with respect to allocation
or cost sharing among PRPs at Harbor Island. EPA has not
allocated relative cost share among PRPs. Allocation of liability
among PRPs will be addressed in future Consent Decree
negotiations with the PRPs for implementation of the remedial
actions selected in this ROD.
Other:
Comment: Although the lead smelter may have been a source of lead
on the island, data indicate that there are other sources of
elevated lead concentrations in the soil.
Response: EPA recognizes that another potential source of lead
found, in the soil is combustion of leaded gasoline from cars and
trucks on the island. However, the distribution of elevated lead
in the soil (see Map 4-43 of the Remedial Investigation Report)
strongly indicates the smelter as the. primary source of lead
contamination.
Comment: In addition to deed restrictions on affected property,
EPA should also consider working with the City of Seattle to
restrict zoning to insure the area remains industrial or to place
deed restrictions on all parcels on Harbor Island to avoid
incompatible uses adjacent to affected areas.
10
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Response: EPA will consider these options. However, zoning
restrictions are subject to political change and processess and
cannot be viewed as comparably reliable or permanent as deed
restrictions.
Comment: EPA should continue to work upstream on the Duwamish and
evaluate contribution to marine sediment from the stream as well
as. from Harbor Island.
Response: As part of the marine sediment remedial investigation,
EPA sampled sediments as far upstream in the Duwamish as Kellogg
Island in an attempt to distinguish upstream sources from Harbor
Island sources. The draft Sediment Remedial Investigation Report
which discusses the results of this sampling is available for
public review at EPA's Record Center, 7th Floor, 1200 Sixth Ave,
Seattle. EPA intends to issue the Feasibility Study and Proposed
Plan for the sediment operable unit next summer.
Comment; There are several Puget Sound Air Pollution Control
Agency (PSAPCA) regulations that PSAPCA considers Applicable or
Relevant and Appropriate Requirement (ARARs) for several of the
options discussed in the soil cleanup plan including the
preferred alternative.
Response; EPA will require that all substantive requirements of
these PSAPCA regulations are met durin.., Implementation of the
selected remedial action.
Comment; There is a misconception that (referring to page 17 of
the Proposed Plan) "thermal desorption is not highly effective
for removing PCBs from soil". Thermal desorbers are no less
efficient than incinerators when operated under the same time and
temperature conditions.
Response: EPA acknowledges that thermal desorbers can effectively
remove PCBs from soil given the proper operating conditions.
However, given that PCB concentrations were found as high as 420
ppm and that EPA's cleanup goal for PCBs is about 3 ppm, this
will require a removal efficiency of greater than 99%. While
this efficiency may be attainable, EPA believes the uncertainty
of obtaining it poses a risk. As an alternative to incineration,
EPA is now providing the option of disposal at a hazardous waste
disposal facility for PCB contaminated soil, which should be more
cost effective than.incineration.
Comment; While the polygon map approach can provide a. reasonable'
basis to screen remedial alternatives for the entire Harbor
Island site, it should not provide the sole basis for determining
11
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areas that: require remediation. Field testing methods will be
useful for distinguishing between soil containing PCBs and soil
containing TPH alone.
Response: Additional soil sampling will be required during the
Remedial Design phase to more accurately determine the areas and
volumes which will require excavation and treatment. Certain
field testing methods, with the appropriate detection limits and
level of accuracy, could be used at that time as a screening
technique to distinguish between PCB and TPH contaminated soil.
Comment; EPA's use of cumulative risk levels as a criterion for
determining cleanup action levels for hot spots is not amenable
to use of field screening methods to define areas requiring
remediation during the Remedial Design phase.
Response: Field screening methods may not be as effective for
defining these hot spot areas since they contain mixtures of
carcinogens (PCBs, arsenic, PAHs). Since these areas contain
mixtures, the corresponding detection limits required for
individual carcinogens will be lower than if they occurred alone.
If appropriate detection limits cannot be achieved with field
screening methods, standard laboratory analytical methods,
similar to those used by EPA during the Remedial Investigation,
will be required.
Comment: On the Seattle Iron & Metals Corporation (SIMC)
property, a PCB concentration exceeding the hot spot criterion
was detected at one location, which was not tested for TPH.
Because it is uncertain if TPH is present at this location, it
cannot be determined if PCBs at that location are mobile. Because
the cost of proposed treatment (offsite incineration) for PCBs is
so high, additional field testing to assess TPH concnetrations at
this location would be worthwhile. If TPH is not present at
significant concnetrations, capping of the PCB contaminated soil
would provide a more cost-effective approach to protecting human
health and the environment.
Response: Enhanced mobility of PCBs in the presence of TPH was
only one of the criteria used by EPA in selecting the cleanup
action level for PCBs. The other criteria is that according to
TSCA regulations, incineration or disposal at a hazardous waste
disposal facility is required for all PCB contaminated soil with
concentrations exceeding 50 mg/kg. EPA will allow disposal at a
hazardous waste disposal facility as an alternative to
incineration for levels of PCBs exceeding 50 mg/kg.
Comment; Based on information regarding SIMC's operations, it
appears unlikely that gasoline or other lighter-weight, more
12
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mobile petroleum hydrocarbons were a significant source of TPH
detected at the SIMC property. Instead, heavier-weight, less
mobile petroleum hydrocarbons are more likely to have been
handled. Thus, EPA should consider capping the TPH hot spot on
the SIMC property/
Response; EPA has made no distinction between the mobility of
lighter-weight or heavier-weight petroleum hydrocarbons. EPA
considers both types of. hydrocarbons to be relatively mobile
compared to other organic and inorganic contaminants found at
Harbor Island. EPA will still reguire treatment of the TPH hot
spot on the SIMC property.
Comment: The use of low-temperature thermal desorption is not
appropriate in every instance because of its limitation in
treatment of heavier petroleum hydrocarbons.
Response: EPA has determined that the concentrations of high
molecular weight PAHs (HPAHs) in the TPH hot spots are not
significantly elevated and can be effectively treated by thermal
desorption and reduced to levels below the cleanup goals.
Through its Research and Development Program, EPA has
demonstrated that thermal desorption technology operated at
higher temperatures and longer soil retention times can remove
HPAHs from soil with a high efficiency.
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APPENDIX B
METHOD FOR DETERMINING HOT SPOT TREATMENT LEVELS
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Appendix B
Method for Selecting Hot Spot Treatment Levels
I. Method Used in the Feasibility Study
The objective of selecting hot spot treatment levels in the
Feasibility Study was to identify areas containing high
concentrations of contaminants in relatively small volumes which
could be excavated and treated, providing an optimal cost-benefit.
The benefit, in this context, is the total mass of contaminant
treated. The first step in the process was to identify the
contaminants presenting the greatest risk to human health and the
environment. This was accomplished by comparing contaminant
concentrations to the cleanup goals to determine which had the
highest exceedances. This process identified lead, mercury,
arsenic, TPH, and PCBs. Arsenic was eliminated at this point
because the distribution of its concentration showed that it was
widely distributed across the island at levels not significantly
above background, and was not highly concentrated in any particular
areas. PCBs were also elimianted from further evaluation because
EPA decided to set its treatment level at an existing regulatory
limit, which is 50 mg/kg as defined by the federal Toxic Substance
Control Act (TSCA).
For TPH, lead, and mercury, the concentrations and soil volumes
associated with these concentrations were reviewed to identify the
approximate.point at which the mass of contaminant started rapidly
decreasing as a function of increased soil volumes. The treatment
levels were selected at the contaminant concentrations where the
incremental amount of contaminant was disproportionate to the
incremental soil volume. The cost to treat these contaminants was
also analyzed semi-quantitatively to verify that the cleanup level
selected was also at the point where the cost per mass of
contaminant treated started rapidly increasing.
For example, treating all lead contaminated soil would result in
treating 5.9 x 106 cubic yards of soil to remove 4.4 x 106 pounds
of lead for an average of 0.75 pounds/cubic yard treated. Treating
soil exceeding 2,000 mg/kg lead would result in an average lead
treatment rate of 40 pounds/cubic yard. Treating soil exceeding
5,000 mg/kg, 10,000 mg/kg and 20,000 mg/kg would result in average
rates of 57, 60, and 100 pounds/cubic yard, respectively. A
noticeable increase in the amount of lead treated percubic yard of
soil occurs at a lead concentration of greater than 10,000 mg/kg.
Therefore, 10,000 mg/kg was selected as the treatment level for
lead. This treatment level contains approximately 85% of the total
mass of lead within 40% of the total volume of lead contaminated
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soil above the cleanup goal. The treatment level selected for TPH,
10,000 mg/kg, contains 66% of the total TPH mass within 14% of the
TPH contaminated soil volume. The treatment level selected for
mercury, 5 mg/kg, contains 27% of th- mass of mercury within £% of
the contaminated soil volume. These results show that the objective
of containing a majority of the contaminant mass in a minimum
volume is achieved at the treatment levels for lead and TPH. The
treatment level for mercury did not capture a majority of the mass
of mercury, because mercury is more evenly distributed as a
function of concentration than TPH or lead.
The corresponding cost analysis for lead, for example, also shows
that as the pounds of contaminant per cubic yard decreases, the
cost to treat each pound rapidly increases. Assuming it costs $100
to treat one cubic yard of soil, the average cost to treat a pound
of lead at soil concentration exceeding 2^000 mg/kg, 5,000 mg/kg,
10,000 mg/kg, and 20,000 mg/kg is $2.50/lb, $1.75/lb, $1.66/lb, and
$1.00/lb, respectively. The cost drops significantly at a lead
concentration exceeding 10,000 mg/kg, indicating it is the cost
effective breakpoint, and therefore, should be the treatment level.
The cost effective breakpoint for TPH occurred at a concentration
of about 10,000 mg/kg, and the breakpoint for mercury occurred at
about 5 mg/kg.
II. Cost-Benefit Analysis of Treatment Levels
After selecting treatment levels in the Feasibility Study, a
cost-benefit analysis was completed for lead, mercury and TPH to
confirm these treatment levels. The analysis involved generating
two types of functions (curves). The first type of curve, .soil
volume versus contaminant mass, was generated by ranking areas with
the particular contaminant in order of highest to lowest
concentration. The curve is based on the cumulative total
contaminant mass and soil volume for each contaminant
concentration. One assumption used in generating this curve was
that the average contaminant concentration is an area is
represented by the single sample taken from that location.
The second type of curve, mass of contaminant treated versus cost
per pound of contaminant, was generated by calculating the
excavation cost and treatment cost, per cubic yard of soil, and
dividing by the mass.of contaminant treated. This process was also
performed using cumulative totals as discussed above. It is
important to note that this figure is semi-quantitative in nature
since it used only excavation and treatment cost elements and did
not include other costs required to implement the treatment
alternative. Simplifying assumptions used to generate these curves
include: 1) soil excavation costs are $2.00 per cubic yard, 2)
excavation and handling costs are $6.00 per cubic yard, 3) lead and
mercury are treated by solidification at a cost of $100 per cubic
yard, 4) TPH is treated by thermal desorption at a cost of $100 per
cubic yard, and 5) the contaminated soil associated with the
Lockheed Shipyard operable unit was included in the calculation but
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the contaminated soil associated with the petroleum tank farm
operable unit was not included.
The volume versus mass curve was ured to determine the point at
which removing and treating additional1 soil volume does not provide
a proportionate degree of benefit in term of mass treated. The mass
versus cost per pound curve was used to determine the cost-benefit
of treating an additional incremental volume of soil. As shown in
each of the figures, the treatment levels generally mark the
location at which signigicantly decreasing quantities of
contaminant mass are treated with each incremental increase in soil
volume removed. The treatment levels also generally locate the
point at which the cost per pound of contaminant treated increases
disproportionally with the soil mass removed.
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20
15
.
r°
hot spot action level
100
200
400
Thousands
Soil Treated (cubic yards)
500
600
12,000
+-• 70,000
91,000
700
RFWSMA-OtiphlA
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10
Millions
• Mass of TPH Treated (pounds)
RfWJ
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C/3
T3
100
Thousands
Soil Treated (cubic yards)
RFWJMA.WK3-ORAPH3
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Millions
Mass of Lead Treated (pounds)
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1200
100
Thousands
Soil Treated (cubic yards)
RFW5MA.WK3-ORAPH4
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I
20
15
R 110
•—
oo
O
u
if
• hot spots •
200
' 400 479 600 800
Mass of Mercury Treated (pounds)
1000
1200
RPVJMA.W10 GRAPH 7
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