oEPA
Commencement Bay South Tacoma Channel Superfund Site
Well 12A	Tacoma, Washington
U.S. Environmental Protection Agency, Region 10	May 2009
Proposed Plan Out for Public Comment
Public Comment Period
May 4,2009 - June 3,2009
Send comments on this Proposed Plan to:
Kira Lynch, EPA Project Manager
U.S. EPA Region 10, ECL-113
1200 6th Avenue, Suite 900
Seattle, WA 98101
Or email: lvnch.kira@epa.gov
Please put "Well 12A Proposed Plan Comments" in the
subject line.
Public Meeting
Tuesday, May 19,2009,6:30-8:30 p.m.
Tacoma Public Utilities Administration Building
3628 South 35th Street (35th and Union)
Tacoma, WA
The U.S. Environmental Protection Agency (EPA), in
consultation with the Washington State Department of
Ecology (Ecology), has prepared a Proposed Plan for the Well
12A Superfund Site located in Tacoma, Washington. Despite
previous cleanup actions, contamination at the site persists,
creating the need for further action.
The Proposed Plan provides an overview of the site history,
contamination, and risk; summarizes the cleanup alternatives
that EPA is considering; and details EPA's preferred remedial
(cleanup) alternative and supporting rationale.
From May 4, 2009 through June 3, 2009, the EPA invites you
to provide your comments on the alternatives for addressing
contaminated soil and groundwater at the site, The site
includes the area surrounding the City of Tacoma Water
Supply Well 12A and the suspected source of contamination,
which is property formerly owned by Time Oil Company.
This plan is based on the Focused Feasibility Study prepared
for the site, as well as other site documents. All site
documents are contained in the administrative record and are
available for public review. Administrative record locations
are listed in the Community Involvement section at the end
of this document.
EPA's preferred remedial (cleanup) alternative includes
excavation and removal of contaminated shallow soils, in situ
(in place) thermal remediation of deep soils, groundwater
extraction and treatment along with in situ treatment of highly
contaminated groundwater through enhanced anaerobic
(without oxygen) biological treatment, and wellhead treatment
at Well 12A,
EPA, in consultation with the Washington State Department of
Ecology, will select a remedy for the site after the public
comment period. Changes to the preferred alternative may
be made based on comments collected during the public
meeting or submitted in writing during the public comment
period, The final decision regarding the selected remedy will
be made and documented in a ROD Amendment after EPA
has taken into consideration all comments from the public,
EPA is issuing this Proposed Plan in consultation with the
Washington State Department of Ecology, as part of its public
participation responsibilities under Section 117(a) of the
Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) of 1980, as amended, and Section
300.430(f)(2) of the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP).
Site Background
The Well 12A Site is one of three distinct sites within the 2.5
square mile Commencement Bay - South Tacoma Channel
Superfund Site in Tacoma, Washington. The two other
distinct sites are the Tacoma Municipal Landfill and South
Tacoma Field. The Well 12A Site has been designated as
Operable Unit 1 (OU1).

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Former Time
Oil Building
WELL 12A
Tacoma
N Washington
A 2
Figure 1
Site Location Map
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Site History
The Well 12A Superfund Site is located approximately 4 miles
southwest of the southernmost tip of Commencement Bay
near the junction of Interstate 5 and Highway 16 (see Figure
1).
The site consists of a primary source area, which is property
formerly owned by the Time Oil Corporation, and a
groundwater contamination plume that extends from the
source area approximately 2,000 feet to the east and
approximately 2,000 feet to the southwest to Well 12A, Well
12A, located on Pine Street between 38th Avenue and South
Tacoma Way, is the northernmost well in the City of Taeoma's
south well field,
Around 1923, a paint and lacquer thinner manufacturing
facility and an oil recycling facility began operating at the site,
The paint and lacquer thinner manufacturing involved the use
of many solvents that were stored on the site in barrels, which
may have leaked. The waste-oil recycling process consisted
of collecting waste oil in a large tank, adding chemicals (such
as sulfuric acid), and pressurizing and heating the contents of
the vessel. Absorbents and clay materials were also added to
the oil. This process resulted in the formation of a tar-like
sludge on the bottom of the tank. The sludge was filtered
from the oil, and the resulting filter cake was disposed of or
stored in various piles on the site. Some of this sludge was
also used for fill around the site.
These operations continued until 1964, when Time Oil
Company acquired the majority of the property at 3100 South
Fife Street, Time Oil continued reprocessing waste oil at the
facility until 1970. From 1970 to 1972, Time Oil used the
facility as a warehouse for tires, batteries, and accessories.
In 1972, Golden Penn, Inc. leased a portion of the facility and
continued the reprocessing operation until 1976 when a fire at
the facility destroyed the waste-oil processing apparatus. In
1975 and 1976, the State of Washington ordered Golden
Penn to remove some of the filter cake and spilled oil from the
ground.
From 1976 until the early 1990s, Time Oil used the site for
warehousing and canning oil. Recent uses of the Time Oil
property include warehousing of heating, ventilating, and air
conditioning (HVAC) equipment and small-scale
manufacturing of kayaks. In 2003, the property was sold to
Western Moving and Storage. Many types of items continue
to be stored at the property today.
Previous Investigations and Remedial Actions
In 1981, chlorinated organic solvents were detected in Well
12A. In high concentrations, these substances can have
harmful health effects. Following a site investigation
conducted by EPA during the summer of 1981, the well was
removed from service. Based on the findings of the
investigation, the Well 12A Site was added to the National
Priorities List (NPL) on September 8, 1983. The Conceptual
Site Model prior to any cleanup activities executed by EPA is
shown below.
Conceptual Site
Model prior to
cleanup
activities
DNAPL
TIME OIL BLD6
[yaaa
gUluifi©
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In accordance with the initial cleanup outlined in the 1983
ROD for the site, an air stripping treatment system was
constructed for Well 12A and began operation in July 1983
whenever the well is pumped. Well 12A and the treatment
system continued to be used to meet peak summer demand
throughout the 1980s and 1990s, Well 12A is typically now
pumped only during the summer or early fall.
Following a remedial investigation and feasibility study, a
1985 ROD for the site detailed additional measures needed to
address site soil and groundwater contamination. The
Burlington Northern Railroad company right-of-way adjacent
to the Time Oil facility was identified as an additional source
of contamination to Well 12A in the 1985 ROD. In June 1986,
Burlington Northern excavated approximately 1,200 cubic
yards of contaminated soils along the rail spur.
In accordance with the 1985 ROD, a groundwater extraction
and treatment system (GETS) was installed to pump and treat
contaminated groundwater near the source on the Time Oil
property in November 1988, The groundwater treatment
system continuously extracts groundwater from the aquifer
under the site and pumps it through activated carbon to
remove volatile organic compounds (VOCs). In 1995, four
additional extraction wells were added to the system. The
objective of the groundwater extraction and treatment system,
which continues to operate, is to limit migration of
contaminants in the groundwater.
In 1987, the 1985 remedy was modified. As a result, in 1993,
a soil vapor extraction (SVE) system was installed and began
operation in the area where drum storage and disposal
operations had previously occurred. During construction of
the soil vapor extraction system, approximately 5,000 cubic
yards of waste sludge (filter cake) from the oil recycling
operations were excavated. Operation of the soil vapor
extraction was discontinued in 1997 after soil contamination
was reduced to concentrations that would not impact
groundwater quality. The Conceptual Site Model shown in the
figure below illustrates the current conditions after the
cleanups were executed by EPA,
In 2004-2005, EPA collected soil and groundwater samples
from the site to assess the effectiveness of the aging
groundwater treatment system, Oily product was identified in
some soil samples, Groundwater contaminant concentrations
had decreased, in general, compared to previous samples,
but elevated concentrations of chlorinated volatile organic
compounds (CVOCs) are still found near the Time Oil
property.
Upper Aquifer
DNAPL
TIME OIL BLDG
Current Conceptual
Site Model
Lower Aquifer

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In September 2008, the third Five-Year Report was completed
for Well 12A. The report found that the groundwater
extraction and treatment system is not reducing contaminant
concentrations and not limiting the migration of contamination
as expected. The extraction wells' pumping rates have
decreased below design rates over time and will likely
continue to decrease due to aging pumps and systems. In
addition, targeted achievable cleanup objectives for both
groundwater and soil have not yet been established. Since
the report concluded that the remedy was not protective,
corrective actions were initiated. EPA conducted a Focused
Feasibility Study analyzing potential remedial alternatives to
address ongoing contamination.
Site Characteristics
The Well 12A Superfund Site consists primarily of
industrial/commercial land, with a small amount of residential
land, in southwestern Tacoma, Washington. The Time Oil
property, located at 3011 South Fife Street, covers 2.5 acres
in the northwest portion of the site, approximately one-third of
a mile north-northeast of Well 12A. Figure 2 on page 6 shows
a map of the site, including the locations of wells installed
during previous remedial actions.
The site is located within the Puget Sound Lowland,
approximately 6 miles south of Commencement Bay and
within the Commencement Bay drainage area. The local
geology is complex and permeability is highly variable across
the site. A semi-confining layer (also called a leaky aquitard)
exists between 120 and 150 feet above sea level. The
shallow groundwater system above the semi-confining layer is
referred to as the upper aquifer and the lower groundwater
system below the semi-confining layer is referred to as the
lower aquifer. The water table occurs at approximately 33
feet below ground surface. Almost no contamination was
detected in the lower aquifer, which suggests that the semi-
confining layer prohibits contamination from migrating
downward.
The contaminants of concern at the site are
tetrachloroethylene (PCE); trichloroethylene (TCE); cis-1,2-
dichloroethene (DCE); trans-1,2-DCE; vinyl chloride (VC); and
1,1,2,2-tetrachloroethane (PCA). TCE is considered to be the
most prevalent compound. Elevated concentrations of TCE
are found in onsite soils and are used to define the extent of
the site groundwater contaminant plume.
Soil contamination is greatest near the surface on the east
side of the Time Oil building. Filter cake is also thought to be
near the surface in this area, which is believed to be a
continuing source of groundwater contamination. TCE is the
most widespread volatile organic compound in groundwater.
Its plume extends to the east of the site and to the southwest
of the site toward Well 12A. Contaminants in the southern
end of the plume are likely accelerated toward Well 12Awhen
it is in operation. Despite previous source removal efforts, a
number of sources of dissolved phase contamination still
remain on or near the Time Oil property. Both light and dense
non-aqueous phase liquids (LNAPL and DNAPL) have been
identified beneath the property and an additional area of filter
cake has been identified to the east of the Time Oil building.
Non-aqueous phase liquids are liquids that do not dissolve or
mix easily with water. Because they do not mix with water,
they form a separate phase. Light non-aqueous phase liquids
are less dense than water and float on top of water.
Hydrocarbons, such as oil and gasoline, are examples of
LNAPLs. Dense non-aqueous phase liquids are denser than
water and sink into the aquifer. Many chlorinated solvents,
such as TCE, are DNAPLs.
Contaminated soils containing residual source material, as
well as filter cake material remaining on the site surrounding
the Time Oil building are considered to be "principal threat
wastes" because the chemicals of concern are found at
concentrations that pose a significant risk. Although
contaminated groundwater also poses a risk, it is not
considered a "principal threat" as defined by EPA guidance.
However, areas of LNAPL and DNAPL are also considered to
be principal threat wastes.
What is a "Principal Threat"? The National Contingency Plan
(NCP) establishes an expectation that EPA will use treatment
to address the principal threats posed by a site wherever
practicable (NCP Section 300.430(a)(1)(iii)(A)). The "principal
threat' concept is applied to the characterization of "source
materials" at a Superfund site. A source material is material
that includes or contains hazardous substances, pollutants or
contaminants that act as a reservoir for migration of
contamination to groundwater, surface water, or air, or acts as
a source for direct exposure. Contaminated groundwater
generally is not considered to be a source material; however,
non-aqueous phase liquids (NAPLs) in groundwater may be
viewed as source material. Principal threat wastes are those
source materials considered to be highly toxic or highly mobile
that generally cannot be reliably contained, or would present a
significant risk to human health or the environment should
exposure occur. The decision to treat these wastes is made
on a site-specific basis through a detailed analysis of the
alternatives using the nine remedy selection criteria. This
analysis provides a basis for making a statutory finding that the
remedy employs treatment as a principal element.
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Scope and Role of the Action
This Proposed Plan addresses contaminated soil and
groundwater at the Well 12A site. In spite of site
removal/remedial activities conducted to date, soil and
groundwater contamination persists. EPA is proposing to
aggressively treat or destroy source area contamination. The
proposed cleanup action will result in a cost-effective remedial
alternative that aggressively destroys contaminant mass and
protects public health and the environment from the potential
risks posed by soil and groundwater contamination.
Summary of Site Risks
Despite previous actions taken at the site, concentrations of
soil contaminants exceed regulatory levels as established by
the Washington State Department of Ecology Model Toxics
Control Act (MTCA). Concentrations of groundwater
contaminants also exceed maximum contaminant levels
(MCLs). Non-aqueous phase liquids have been identified in
the soil and groundwater. Vapor intrusion in onsite buildings
is also a concern.
The area is developed by commercial and industrial
businesses, and it is likely that this will not change. Examples
of businesses located within the groundwater plume are
machine shops, restaurants, industrial supply and storage
space. The recommended alternative presented in this plan,
or another active measure considered in this document, is
needed to protect public health and the environment from
risks posed by site soil and groundwater. Vapor intrusion will
be evaluated by EPA after targeted soil and groundwater
contamination is addressed.
Contaminant concentrations in site soil exceed the
Washington State Department of Ecology Model Toxics
Control Act B cleanup levels. Soil to groundwater cleanup
levels are also exceeded. The presence of soil contamination
is an ongoing source of contamination to groundwater.
Because groundwater concentrations also exceed MCLs,
untreated groundwater could result in risk to human health via
failure of the treatment system at Well 12A, migration of
contaminants to another Tacoma well that does not have
treatment, or inhalation of process vapors of process water
from a hypothetical industrial well. The groundwater
contaminant plume has extended to Well 12A. Well 12A is
currently treated with an air stripper when used, however
down gradient City of Tacoma wells do not have treatment
systems. Well 9A, which is 1100 feet west/southwest down
gradient of Well 12A, has already shown measurable
detections of TCE. Changes to City of Tacoma pumping rates
in the future would result in further migration of the
groundwater plume that would cause contaminant levels
above MCLs reaching other municipal supply wells unless
actions such as the ones proposed in this plan are
implemented.
Ecological Risks
No significant impacts to ecological receptors are predicted
because the site is located in a largely developed area and
the current contaminant plume does not reach nearby
streams or rivers.
It is EPA's current judgment that the preferred alternative
identified in this Proposed Plan, or one of the other active
measures considered in this plan, is necessary to protect
human health and the environment from actual or threatened
releases of hazardous substances.
Human Health Risks
Public health would be threatened either by direct contact at
the source area or by consumption of contaminated drinking
water if no additional remedial action is taken. Each of the
contaminants of concern affects similar organs: the eyes,
skin, liver, respiratory system and central nervous system.
Assuming residential land use, exposure scenarios that would
impact human health if no further action is taken are:
Shallow soil/filter cake: Ingestion and dermal contact
Groundwater: Ingestion, dermal contact, and inhalation of
vapors
Remedial Action Objectives
Conceptual Site Model
The conceptual site model (which includes the nature and
extent of contamination, the location of contamination, and the
transport of contaminants) was used to identify four zones or
areas that need to be addressed by some cleanup action.
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Filter Cake and Shallow Impacted Soil
This zone needs to be addressed because it is at the surface
and it appears to be contributing to subsurface contamination.
Deep Vadose Zone Soil and High Concentration Groundwater
East of Time OH Building
The vadose zone, also called the unsaturated zone, extends
from the surface to the water table (saturated zone). Since
technologies applied in the deep vadose zone would likely be
applicable to the upper saturated zone, the two media are
combined into this one treatment zone. The extension of
vadose zone contamination into the water table suggests that
it is a continuing source of contamination. If left untreated,
these high concentrations of contamination would continue to
impact groundwater.
High Concentration Groundwater West and South of Time Oil
Building (TCE and cis- 1,2-DCE greater than 300 ug/l)
This area is predominantly defined by groundwater with TCE
and cis-1,2-DCE at concentrations above 300 ug/l. The 300
|jg/L concentration was chosen because, beyond this
concentration, negligible additional contaminant mass is
gained. Also, where contamination drops below 300 ug/l, the
aquifer begins to transition from anaerobic conditions (without
oxygen) to aerobic conditions (with oxygen). Also included in
this zone are the area east of the Time Oil building with
elevated concentrations of 1,1,2,2-PCA and the area
southwest of the Time Oil building for which limited data are
available.
Low Concentration Groundwater (TCE and cis-1,2-DCE less
than 300 ug/l)
This treatment zone includes groundwater with concentrations
of TCE/cis-1,2-DCE less than 300 ug/l. Groundwater data
from wells in this zone indicate that the degradation of
chlorinated volatile organic compounds is probably occurring
naturally under current conditions.
Remedial Action Objectives
Remedial Action Objectives (RAOs) have been developed for
each zone as follows:
•	Eliminate the risk of direct contact with filter cake and
contaminated soil at and near the surface.
•	Prevent or minimize the migration of contamination
from the highly contaminated shallow soil and filter
cake area into the deeper soils to prevent further
degradation of groundwater.
•	Eliminate/minimize the mass of contaminants in the
source area to reduce the migration of this highly
contaminated area into downgradient groundwater.
•	Reduce the discharge of contaminants by 90%, a
remediation level, from the source area into the low
concentration groundwater treatment zone.
•	Reduce contaminant concentrations to meet all
applicable and relevant or appropriate requirements
(ARARs) at specified points of compliance. Points of
compliance designate the location on the site where
the cleanup levels must be met. These points are
established close to the source of contamination to
ensure protection of human health and the
environment. At the Well 12A Site, the designated
points of compliance are: Well 12A (see Figure 1),
proposed well CW-1 (approximately 1250 feet east
of the Time Oil building), and proposed well CW-2
(approximately 1250 feet southeast of the Time Oil
building).
Summary of Remedial Alternatives
Given the complexity of the site, no single remedial
technology would be appropriate as a site-wide remedy. EPA
has developed four remedial action alternatives comprised of
combinations of the general response actions and
technologies identified, screened, and retained in the Focused
Feasibility Study. Thus, for the purpose of developing and
evaluating appropriate remedial alternatives, the site was
divided into the four treatment zones outlined above. Each of
the alternatives described below includes a combination of
individual technologies designed to address the four treatment
zones.
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Alternative 1: No Action
Capital Cost:	$0
Annual Operations & Maintenance (O&M)
Costs:	$0
Total Present Worth: $0
The no action alternative is considered in accordance with
NCP requirements and provides a baseline for comparison
with the other alternatives. Under this alternative, no action
would be taken to remedy the filter cake and shallow
contaminated soils. The status of the deep vadose soil and
shallow groundwater would remain unchanged. The
groundwater extraction and treatment system would be shut
down and the air stripping towers at Well 12A would not be
operated. The status of the site groundwater would not be
changed. CERCLA (Section 121(c)), as amended by SARA
(1986), would require that the site be reviewed at least every
5 years since contamination would remain on site. This
alternative does not include the implementation of any
institutional controls such as deed restrictions or future
groundwater monitoring.
Alternative 2: Institutional Controls and
Existing Groundwater Treatment
Capital Cost:	$0.15 million
Annual O&M Costs:	$0.25 million
Total Present Worth: $5.1 million
Institutional Controls (ICs)
Alternative 2 includes institutional controls to limit access to
and future development, improvement, and use of affected
properties, to protect human health. ICs would include activity
and use restrictions enacted through proprietary (e.g.,
easements, covenants) and/or governmental (e.g., zoning
requirements) controls to prevent the use of the property that
would pose an unacceptable risk to receptors (i.e., for
residential use). Informational device ICs (e.g., warning
signs, advisories, additional public education) would also be
employed to limit access to contaminated soils and
groundwater. Tacoma-Pierce County Board of Health
Resolution No. 2002-3411, Land Use Regulations and
applicable sections of Washington Administrative Code Titles
173 and 246 are current guidelines that would be considered,
or possibly amended, for the location and installation of
supply wells. An additional component of this alternative
involves the continued monitoring of groundwater at the site
for a period of 30 years. In accordance with CERCLA, this
alternative would be evaluated at least every five years
because contaminants would remain on site with this
alternative.
Groundwater Extraction and Treatment
This alternative also includes the continued operation and
maintenance of the existing groundwater extraction and
treatment system to treat groundwater contamination. It does
not include system replacement if the life cycle of the
treatment plant is reached. Although the system has been
operating for 20 years, substantial contaminant mass still
remains in the soil and groundwater. Continuing to operate
the groundwater extraction and treatment system will help
limit the migration of contaminants away from the site. If no
other aggressive actions are taken to reduce contaminant
mass, the groundwater extraction and treatment system may
need to continue to operate for an extended period. For cost
estimating purposes, the duration of this alternative was
assumed to be 30 years.
Wellhead Treatment at Well 12A
In 1983, five air stripping towers were installed to treat the
discharge water at Well 12A. Tacoma Water has operated
and maintained the towers since their installation. This
alternative also includes the operation and maintenance of the
five air stripping units for a period of 30 years and monitoring
groundwater for volatile organic compounds at Well 12A. In
addition, monitoring groundwater quality and attenuation
between the source area and Well 12A are included in this
alternative. Data suggest that naturally occurring attenuation
is contributing to the breakdown and reduction of
concentrations of volatile organic compounds in the low
concentration groundwater plume. Natural attenuation occurs
when physical, chemical, or biological processes act naturally
to reduce the groundwater contamination. Nature can work in
several ways to cause attenuation. 1) Microbes that live in
soil and groundwater use some chemicals for food and, upon
digestion, turn them into water and harmless gases. 2)
Chemicals can stick to soil, which does not clean up the
chemicals, but keeps them from polluting groundwater and
leaving the site. 3) As pollution moves through soil and
groundwater, it can mix with clean water, thus diluting the
contamination. 4) Some chemicals, like oil and solvents, can
evaporate and escape to the air at the ground surface where
sunlight may destroy them. A health and safety plan would be
developed and implemented to protect workers from contact
to groundwater contaminants.
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Alternative 3: Excavation; In situ Thermal
Remediation; Enhanced Anaerobic
Bioremediation (EAB); Groundwater Extraction
and Treatment; Wellhead Treatment;
Institutional Controls
Capital Cost:	$9.3 million
Annual O&M Costs:	$0.98 million
Total Present Worth: $14.2 million
Excavation and Disposal of Soils in RCRA Subtitle C or D
Landfill
This alternative consists of excavating filter cake and
contaminated soils and transporting the waste off site to a
RCRA-permitted landfill. An average excavation depth of 10
feet has been assumed; however, more or less excavation
may be required based on observations and data to be
collected during the remedial action. Assuming an average
excavation depth of 10 feet, approximately 4,200 cubic yards
of contaminated soils would require excavation and disposal.
After the removal, the excavations would be backfilled with
clean soil and gravel cover would be placed across the site
surface. For areas where contaminated soils remain, further
treatment would be performed and institutional controls, such
as deed restrictions and information devices, would be used
to further reduce the potential for exposure. Water would be
used to minimize fugitive dust emissions during soil
excavation, transport, and handling. Any stockpiles of material
during interim storage would be covered by tarps or plastic
sheeting to minimize fugitive dust emissions and runoff
releases. Surface water runoff, fugitive emissions and treated
soils would be monitored to ensure that the remedial action
objectives were being met.
In situ Thermal Remediation
In situ thermal treatment methods heat polluted soil and
groundwater. The heat helps push chemicals through the soil
toward collection wells. The heat can also destroy or
evaporate certain types of chemicals. When they evaporate,
the chemicals change into gases, which move more easily
through the soil. Collection wells capture the harmful
chemicals and gases and pipe them to the ground surface for
cleanup. Thermal methods can be particularly useful for
DNAPLs and LNAPLs, which do not dissolve or move easily
in groundwater and would remain a source of groundwater
pollution for a long time without proper treatment.
Enhanced Anaerobic Bioremediation (EAB)
This component of Alternative 3 consists of in situ (in place)
treatment of contaminated groundwater through enhanced
anaerobic (not needing oxygen) biological treatment.
Bioremediation allows natural processes to clean up harmful
substances in the environment. Microbes that live in soil and
groundwater like to eat certain harmful chemicals, such as
those found in gasoline and oil spills. When microbes
completely digest these chemicals, they change them into
water and harmless gases such as carbon dioxide. In order
for microbes to clean up harmful chemicals, the right
temperature, nutrients, and amount of oxygen must be
present in the soil and groundwater. If conditions are not right
at a site, EPA works to improve them. At the Well 12A Site,
TCE and cis-1,2-DCE could be effectively broken down with
the addition of an amendment (carbon food source) to jump
start the process. Monitoring will be performed to track the
progress of the remedy.
Groundwater Extraction and Treatment
This alternative also includes the continued operation of the
existing groundwater extraction and treatment system to
prevent migration of contaminants while their mass is reduced
via enhanced anaerobic bioremediation. Operation of the
groundwater extraction and treatment system will be
terminated when it is shown that: (1) mass flux (the rate of
movement of contamination) has been reduced by 90% in the
high concentration groundwater area, and (2) concentrations
of contaminants are below maximum contaminant levels at
the specified compliance points in the low concentration
groundwater area.
Wellhead Treatment at Well 12A
See Alternative 2 for details on Wellhead Treatment at Well
12A. Groundwater monitoring and attenuation between the
source area and Well 12A is also included in Alternative 3. As
mentioned above, data suggest that naturally occurring
attenuation is contributing to decreasing concentrations of
volatile organic compounds in the lower concentration
groundwater plume. The enhanced anaerobic bioremediation
being implemented upgradient from this area is expected to
increase this process in the low concentration plume.
Institutional Controls
This alternative also includes institutional controls as
described in Alternative 2.
Alternative 3 is EPA's preferred alternative.
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Alternative 4: Excavation; Capping: In situ
Thermal Remediation; Enhanced Anaerobic
Bioremediation; Air Sparging and Soil Vapor
Extraction; Groundwater Extraction and
Treatment; Wellhead Treatment; Institutional
Controls
Capital Cost:	$11.1 million
Annual O&M Costs:	$1.2 million
Total Present Worth: $16.5 million
anaerobic bioremediation is proposed for most of the plume.
Existing soil vapor extraction equipment and wells are at the
site.
However, since the equipment has not been used in more
than ten years and a cursory inspection of the equipment
revealed poor conditions, the equipment was assumed to be
unusable for this estimate. If the alternative is selected, a
detailed inspection and evaluation can be performed during
design to determine if any of the equipment (including wells)
is usable. Field pilot studies will be necessary to adequately
design and evaluate the system.
This alternative includes all of the following actions that were
included in Alternative 3 described on page 10:
Excavation
In situ Thermal Remediation
Enhanced Anaerobic Bioremediation
Wellhead Treatment at Well 12A
See Alternative 3 for details on how these technologies would
be implemented at the site. In addition, Alternative 4 would
include:
Air Sparging and Soil Vapor Extraction
This alternative uses in situ air sparging (AS) coupled with a
soil vapor extraction system to remove volatile organics from
the groundwater. Soil vapor extraction removes harmful
chemicals, in the form of vapors, from the soil above the water
table. Vapors are the gases that form when chemicals
evaporate. The vapors are extracted from the ground by
applying a vacuum. Air sparging uses air to help remove
harmful vapors from polluted soil and groundwater below the
water table. When air under pressure is injected into a well
installed within the groundwater plume, the chemicals
evaporate faster, which makes them easier to remove. Like
soil vapor extraction, a vacuum then extracts the vapors.
Certain chemicals, like solvents and fuels, evaporate easily.
Soil vapor extraction and air sparging work best on these
types of chemicals and are often used at the same time to
clean up both soil and groundwater. Therefore, air sparging
and soil vapor extraction are well suited for the treatment of
the chlorinated volatile organic compounds found at the site.
The locations of the air sparging and soil vapor extraction
wells are proposed for the area west of the Time Oil building.
The air sparging and soil vapor extraction is proposed in a
small portion of the high concentration plume, but enhanced
Groundwater Extraction and Treatment
This alternative includes the operation of the existing
groundwater extraction and treatment system to prevent
migration of contamination while contaminant mass is being
reduced via air sparging and soil vapor extraction and
enhanced anaerobic bioremediation. Operation of the
groundwater extraction and treatment system will be
terminated when it is shown that concentrations of site
contaminants have been reduced and the mass discharge of
contaminants of concern meets the RAO.
Capping
An asphalt cap would be placed on the area excavated.
Currently, a concrete pad is located in a large portion of the
area to be excavated. The pad will be removed during the
excavation and the asphalt cap will be installed as a
replacement to prevent direct contact exposure and reduce
infiltration. Additionally, the cap will reduce infiltration of
rainwater to a negligible amount so that percolating
precipitation will not be a major transport mechanism from the
soil to the groundwater.
Institutional Controls
This alternative also includes institutional controls as
described in Alternative 2.
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Evaluation of Alternatives
EPA evaluates remedial alternatives retained for detailed
analysis using nine standard criteria. The criteria fall into
three groups: threshold, primary balancing, and modifying.
Each alternative must meet the threshold criteria. The
primary balancing criteria are used to weigh major trade-offs
among alternatives. Modifying criteria may be fully
considered among alternatives. Modifying criteria may be
fully considered only after public comment is received on the
Proposed Plan.
Below is the "Evaluation Criteria for Superfund Remedial
Alternatives". On page 13 is the Comparative Analysis of
Alternatives summarized in a table. Within the table are
ratings indicating how well the alternatives meet the
evaluation criteria. For all but the No Action Alternative,
alternatives are given a rating for each treatment zone
(shallow soil and filter cake, deep vadose zone soil and
groundwater east of the Time Oil building, high concentration
groundwater, and low concentration groundwater). Multiple
ratings are provided because the alternatives treat each zone
differently. For more detailed information on the analysis of
the alternative evaluation, see the Focused Feasibility Study
which can be found on the web site listed on page 15.
	EVALUATION CRITERIA FOR SUPERFUND REMEDIAL ALTERNATIVES	
THRESHOLD CRITERIA
Overall Protectiveness of Human Health and the Environment determines whether an alternative eliminates, reduces, or
controls threats to public health and the environment through institutional controls, engineering controls, or treatment.	
Compliance with ARARs evaluates whether the alternative meets Federal and State environmental statutes, regulations, and
other requirements that pertain to the site, or whether a waiver is justified.	
	PRIMARY BALANCING CRITERIA	
Long-term Effectiveness and Permanence considers the ability of an alternative to maintain protection of human health and
the environment over time.	
Reduction of Toxicity, Mobility, or Volume of Contaminants through Treatment evaluates an alternative's use of treatment
to reduce the harmful effects of principal contaminants, their ability to move in the environment, and the amount of
contamination present.	
Short-term Effectiveness considers the length of time needed to implement an alternative and the risks the alternative poses
to workers, residents, and the environment during implementation.	
Implementability considers the technical and administrative feasibility of implementing the alternative, including factors such as
the relative availability of goods and services.	
Cost includes estimated capital and annual operations and maintenance costs, as well as present worth cost. Present worth
cost is the total cost of an alternative over time in terms of today's dollar value. Cost estimates are expected to be accurate
within a range of +50 to -30 percent.	
	MODIFYING CRITERIA	
State/Support Agency Acceptance considers whether the State agrees with the EPA's analyses and recommendations, as
described in the RI/FS and Proposed Plan.	
Community Acceptance considers whether the local community agrees with EPA's analyses and preferred alternative.
Comments received on the Proposed Plan are an important indicator of community acceptance.
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SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Alternative
Evaluation Criteria

Overall Protection
of Human Health
and the
Environment
Compliance with
ARARs
Long-term
Effectiveness and
Permanence
Reduction of Toxicity,
Mobility, or Volume of
Contaminants
through Treatment
Short-term
Effectiveness
Implementability
Present Worth
Alternative 1: No Action
0
0
NE
NE
NE
NE
$0
Alternative 2: Institutional
Controls and Existing
Groundwater Treatment
Shallow Soil: 1
Deep Soil: 1
High Cone. GW: 3
Low Cone. GW: 5
Shallow Soil: 1
Deep Soil: 1
High Cone. GW: 3
Low Cone. GW: 5
Shallow Soil: 1
Deep Soil: 1
High Cone. GW: 2
Low Cone. GW: 4
Shallow Soil: 1
Deep Soil: 1
High Cone. GW: 3
Low Cone. GW: 3
Shallow Soil: 1
Deep Soil: 4
High Cone. GW: 4
Low Cone. GW: 4
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 5
Low Cone. GW: 5
$5.1
Alternative 3: Excavation;
In situ Thermal
Remediation; Enhanced
Anaerobic Bioremediation;
Groundwater Extraction and
Treatment; Wellhead
Treatment; Institutional
Controls
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 4
Low Cone. GW: 5
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 4
Low Cone. GW: 5
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 5
Low Cone. GW: 5
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 5
Low Cone. GW: 3
Shallow Soil: 4
Deep Soil: 3
High Cone. GW 3:
Low Cone. GW: 4
Shallow Soil: 4
Deep Soil: 4
High Cone. GW: 3
Low Cone. GW: 5
$14.0
Alternative 4: Excavation;
Capping: In situ Thermal
Remediation; Enhanced
Anaerobic Bioremediation;
Groundwater Extraction and
Treatment; Wellhead
Treatment; Institutional
Controls
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 4
Low Cone. GW: 5
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 4
Low Cone. GW: 5
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 2
Low Cone. GW: 4
Shallow Soil: 5
Deep Soil: 5
High Cone. GW: 5
Low Cone. GW: 3
Shallow Soil: 4
Deep Soil: 4
High Cone. GW: 4
Low Cone. GW: 4
Shallow Soil: 4
Deep Soil: 4
High Cone. GW: 3
Low Cone. GW: 5
$16.4
Key: NE = Not Evaluated 0 =
No Compliance 1 = Low 2 = Low to Moderate 3=Mod
Cone. = Concentration GW = Groundwater
erate 4=Moderate to High 5=Hig
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Summary of the Preferred Alternative
The Preferred Alternative for cleaning up the Well 12A Site is
Alternative 3, which includes: excavation of an average of 10
feet of shallow soil and remaining filter cake, in situ thermal
remediation of deep soil and high concentration groundwater
east of the Time Oil building, enhanced anaerobic
bioremediation and groundwater extraction and treatment of
high concentration groundwater west and south of the Time
Oil building, wellhead treatment of low concentration
groundwater, and institutional controls. In addition, low
concentration groundwater will be further treated because the
effects of bioremediation in the adjacent high concentration
groundwater zone are expected to improve the capacity of the
aquifer to naturally reduce contaminant levels in the low
concentration groundwater zone.
The preferred alternative was selected because it is expected
to achieve substantial, long-term risk reduction through
treatment and source removal. In addition, Alternative 3
would reduce risk within a reasonable time frame and at less
cost than Alternative 4. The institutional controls would be
easily implemented, involving some administrative tasks, but
no construction activities. The proposed excavation is in a
relatively open area (i.e., minimal structure interference) and
the estimated depths can be reached with standard
equipment. The groundwater extraction and treatment system
is constructed and is being operated and maintained.
Similarly, the treatment system at Well 12A has been
constructed and operated since 1983. It is estimated that
construction of the in situ thermal remediation treatment
system could be completed within six months of site
mobilization and that the heating phase would last
approximately six months. Therefore, the estimated time for
the contaminant mass in this source area to be reduced by at
least 90% is one year. Enhanced anaerobic bioremediation
would require a testing program prior to implementation to
refine the treatment technology's design. Using the speed of
groundwater movement, EPA can estimate how long it will
take for impacts from the bioremediation to reach specified
points. For example, the distance from the south edge of
South Tacoma Way (a proposed location to receive enhanced
anaerobic bioremediation) to Well 12A is approximately 1,400
feet. Given that groundwater is moving on average at about
0.42 feet per day, impacts from the bioremediation are
estimated to reach Well 12A in 3,333 days, or about 9 years.
This estimate is based on current data and conditions; if
additional data are collected or conditions change, then the
estimate may change. For example, if the velocity is faster
(e.g., two times faster) than estimated because the
subsurface material differs in some areas then the impacts
would be seen two times faster (4.5 years instead of nine
years).
Based on the information at this time, EPA and the State of
Washington believe that the Preferred Alternative would be
protective of human health and the environment, would
comply with ARARs, would be cost-effective, and would utilize
permanent solutions and alternative treatment technologies to
the maximum extent practicable. The Preferred Alternative
can change in response to public comment or new
information.
Community Involvement
EPA and the Washington State Department of Ecology rely on
public input to ensure that the concerns of the community are
considered in selecting a remedy for the site. To this end, this
Proposed Plan and other site documents have been made
available to the public for a public comment period which
begins on May 4 and concludes on June 3, 2009.
A public meeting will be held on May 19, 2009, 6:30 - 8:30
p.m. at the Tacoma Utilities Administration Building, 3628
South 35th Street (35th and Union), to present the conclusions
of the FFS, further elaborate on the reasons for
recommending the preferred alternative, and to receive public
comments. EPA, in consultation with the State of
Washington, will select a remedy for the site after
consideration of all public comments. The final decision will
be published in the ROD Amendment. All comments received
during the public comment period will be documented, along
with EPA's response to each comment, in the
Responsiveness Summary section of the ROD Amendment.
EPA and the State of Washington encourage the public to
gain a more comprehensive understanding of the site and the
Superfund activities that have been conducted to date.
Copies of site documents can be reviewed as they become
available, at the following locations:
U.S. Environmental Protection Agency
1200 Sixth Avenue, Suite 900
7th Floor Records Center
Seattle, WA 98101
206-553-4494
Citizens for a Health Bay
917 Pacific Avenue, Suite 100
Tacoma, WA 98402
253-383-2429
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Documents will also be posted on the EPA website
http://vosemite.epa.gov/r10/cleanup.nsf/sites/cbstc. If you
have questions or for more information, contact
Kira Lynch
EPA Project Manager
206-553-2144,
or toll free at 1-800-424-4372, ext. 2144
or by email at lynch.kira@epa.qov.
Alternative formats are available. For reasonable
accommodations, please call:
Jeanne O'Dell
EPA Community Involvement Coordinator
206-553-6919
or toll free at 1-800-424-4372, extension 6919
or by email at odell.ieanne@epa.qov.
Caryn Klaff
EPA Community Involvement Coordinator
206-553-1275
or toll free at 1-800-424-4372, extension 1275
or by email at klaff.carvn@epa.gov.
TTY users, please call the Federal Relay Service at 1-800-
877-8339.
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vvEPA
U.S. Environmental Protection Agency
1200 Sixth Avenue, Suite 900. ETPA-081
Seattle. Washington 98101-3140
Pre-Sorted Standard
Postage and Fees Paid
U S EPA
Permit No. G-35
Seattle, WA
Public Meeting, May 19, 2009
Proposed Plan - Well 12A
Commencement Bay. South Tacoma Channel
Tacoma, Washington

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