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P.O. Box 1209
Seattle, WA 98111-1209
Tel: 787-3000
www.portseattle.org
P.O. Box 1209
Seattle, WA 98111-1209
Tel: 787-3000
www.portseattle.org
P.O. Box 1209
Seattle, WA 98111-1209
Tel: 787-3000
www.portseattle.org
P.O. Box 1209
Seattle, WA 98111-1209
Tel: 787-3000
www.portseattle.org
P.O. Box 1209
Seattle, WA 98111-1209
Tel: 787-3000
www.portseattle.org
SUSTAINABLE DESIGN APPROACH / SUSTAINABLE DESIGN STRATEGY
H
ARBOR ISLAND MARINA DOCK-E FLOATS AND NORTH PIER IMPROVEMENTS
PURPOSE
This serves as a summary document for the sustainable design coordination for the Harbor Island
Marina (HIM) Dock-E Floats and North Pier Improvements project. Additional information can be
found in Project Management’s Notebook.
SUSTAINABLE DESIGN APPROACH
The HIM Dock-E Floats and North Pier Improvements projects has been identified as a Tier 2 project
under the Sustainable Evaluation Framework Policy Directive (SEF Policy Directive) adopted by the
Port of Seattle Commission in January 2020. Tier 2 projects are described as:
Tier 2: Medium-sized, or more complex, projects that have opportunities for sustainability benefit
would be subject to targeted sustainability analyses and strategies. Tier 2 projects may receive a
cost per ton of carbon calculation.
The HIM Dock-E Floats and North Pier Improvements project consists of the following elements (see
Figure 1):
• Complete replacement of 23 (out of 78 total) of Dock-E’s existing float sections with new
heavier duty floats, steel piles, and appurtenances designed for larger vessel berthing and
higher load mooring capability.
• Refurbishment of 55 (out of 78 total) of Dock-E’s existing float sections consisting of replacing
all remaining timber guide piles with higher load capacity steel piles; replacement of damaged
walers and cleats; nominal leveling; and concrete surface crack repairs and sealing.
• Demolition and replacement of Dock-E’s existing North Pier to restore vehicle access to it.
Item No: 8e_Attach
Meeting Date: April 11, 2023
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Figure 1. HIM Dock-E Floats and North Pier Improvements
Following the project kickoff meeting, the Project Manager and Sustainability Coordinator assembled
a Sustainable Project Assessment and Review Collaboration (SPARC) team. The SPARC team
leverages port expertise and knowledge of existing and emerging sustainability practices to:
(1) Identify, review, brainstorm, and recommend sustainability concepts and ideas for project and
operational teams to consider and evaluate during the development and design stage of port projects.
(2) Encourage project and operational teams to evaluate and consider innovative strategies to reduce
emissions and energy use beyond traditional approaches.
(3) Select and apply the relevant Sustainable Evaluation Framework criteria to highlight tradeoffs
and benefits during development of the Sustainable Design Approach (SDA).
PROJECT GOALS
The SPARC team met in January 2020 to solidify project goals which were shared with the designer to
identify potential design alternatives/strategies to move forward into the 30% design process. Given
the limited nature of the project’s scope, only a few sustainability goals were concentrated on.
However, though sustainability aspects such as well-being and equity are not addressed directly, they
are included in the project’s general requirements.
• Sustainable Asset Management
o Upgrade structural integrity and load capacities to meet existing uses
Restore vehicle access to North Pier
Avoid future structural damage to dock
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• Habitat
o Look for cost effective opportunities to enhance habitat, such as
Including light transmissivity elements such as “open grating”
Removing angular rock from bankline to increase potential for shoreline
vegetation
Removing debris from the bankline and seabed
o Consider use of Reinhall piles to reduce underwater noise during pile driving
• Materials
o Consider alternative design materials for replaced structures
Low-embodied carbon concrete
Alternatives to concrete
Alternative flotation materials
• Water Quality
o Look into options to address spill containment where feasible
• Financial Sustainability
o Balance project cost and function against environmental benefits
SUSTAINABLE EVALUATION FRAMEWORK CRITERIA
The goals identified by the SPARC team support three of the seven criteria articulated in the SEF
Policy Directive:
• Reduce GHG Emissions. The design acknowledges the need for shore power and will
accommodate the existing system during float replacement. We will prioritize locally sourced
and recycled materials where possible to reduce lifecycle emissions.
• Increase Resilience. The proposed improvements will upgrade the existing system to provide
necessary structural support, limiting future damage to the existing structures and allowing for
the docks to meet current and future intended function.
• Protect Health and the Environment. This project focuses on the replacement and upgrade of
existing infrastructure while limiting environmental impacts. Goals focus on materials, habitat,
and water quality.
• Support Local Economic Development/Advance Equity. Prioritize WMBE and local
business use in contracting and material sourcing.
THIRD PARTY CERTIFICATION
The SDA is required to include a recommendation as to whether a project should pursue an applicable
third-party sustainability certification (such as LEED or Envision.) Staff does not recommend
pursuing certification for this project due to its limited scope but may apply principles from the
American Society of Civil Engineers “Envision” rating system to help inform the design as
appropriate.
SUSTAINABLE DESIGN STRATEGY
A Sustainable Design Meeting was held on February 22, 2021. The Project Manager and
Sustainability Coordinator worked with our design consultant, Reid Middleton, to create a Sustainable
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Design Report for the project. Based on the objectives above, Sustainable Asset Management and
Habitat objectives will be met regardless of project alternative. Water Quality, Materials, and
Financial Sustainability were evaluated for the float guide piling system, replaced South Float System,
and replaced North Pier.
FLOAT GUIDE PILING
Current system: steel piling and treated timber, treated timber to be removed and replaced
Infeasible replacement alternatives:
• Composite piling is not feasible structurally due to proposed loads and substrate conditions
• Concrete piling is not feasible unless all piles are replaced (cannot mix concrete piles with steel
piles)
• Reinhall piling not feasible due to size (Reinhall available at 18” diameter)
• Treated timber pile is not recommended due to environmental concerns
• Thicker steel piles not feasible unless all piles are replaced (cannot mix pile sizes)
Feasible steel pile replacement alternatives:
Alternatives
Water Quality Impacts
Materials
Financial Sustainability
Cost
Design Life
12” ½” Wall Steel Pile
None identified
Needs to be replaced
quicker, wasting more
material
$60,000
25 years
12” ½” Wall Steel Pile:
Galvanized
Release of zinc into the
environment
Longer design life
$66,000
45 years
12” ½” Wall Steel
Pile: Epoxy-coated
None identified
Longer design life,
coating maintenance
due to abrasion
$77,000
35 years
12” ½” Wall Steel Pile:
Galvanized and Epoxy-
coated
Can release zinc into
environment if coating is
abraded
Longer design life,
coating maintenance
due to abrasion
$165,000
60 years
12” ½” Wall Steel Pile:
Galvanized and HDPE
Sleeve
Increases submerged land
impact, can release zinc into
environment if sleeve fails
Longer design life,
sleeve maintenance
$99,000
55 years
NOTE: Alternatives analyses in this document use color coding to help identify the tradeoffs between alternatives. Green shading
represents an alternative that advances project goals, yellow represents neutral impact, and red represents an alternative that does not
advance goals. The highlighted row is the recommended alternative.
Alternative selection:
There are environmental concerns with having galvanization exposed to the environment. High levels
of zinc have been found in stormwater, which has been attributable to galvanized metal surfaces, motor
oil and hydraulic fluid, and tire dust. The Department of Ecology has an initiative to remove zinc from
the environment as part of its purview over stormwater and the Port of Seattle strives to limit the
amount of galvanized materials in the environment by recommending the use of regular steel, stainless
steel, or coatings over galvanized metal. This has typically been discussed in the context of upland
applications and we are currently exploring application of this standard to in-water projects.
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The upfront cost and life of both galvanized steel and epoxy-coated steel is similar. However, long-
term maintenance costs of epoxy-coated steel could be higher since there is the potential for coating
abrasion due to rubbing of the floating dock against the pile. This also reduces its expected design life.
The Port of Seattle does not typically use coated steel and we therefore have no information on life and
maintenance costs for coated piles. Washington State Ferries commonly uses coated steel and we have
requested information from them. This information and other research will inform the Port’s final
approach.
In consultation with the Port Stormwater Utility, Engineering, and Marine Maintenance, we propose
this project as a pilot using coated steel. Its life and condition will be assessed yearly. This is a good
location for a pilot since the piles are easily accessible for repair and maintenance purposes.
SOUTH FLOAT REPLACEMENT
Current system: concrete floats
Infeasible replacement alternatives:
• Aluminum and plastic float systems are not feasible due to the design loads for the facility
• Concrete floats are not feasible since they cannot allow for light penetration (code compliance)
• Composite frame is not feasible due to structural integrity
• Uncoated steel is not feasible due to corrosion, aesthetics, and safety concerns
• Coated steel decking is not a common product and is therefore not analyzed
Feasible float replacement alternatives:
Design
Component
Alternatives
Water Quality
Impacts
Materials
Financial Sustainability
Cost
Design Life
Frame
Galvanized Steel
Frame
Release of zinc into
the environment
Longer design life
$95,000
45 years
Steel Frame with
Epoxy Coating
None identified
Longer design life,
coating maintenance
due to abrasion
$110,000
35 years
Galvanized Steel
Frame with Epoxy
Coating
Can release zinc
into environment if
coating is abraded
Longer design life,
coating maintenance
due to abrasion
$190,000
60 years
Decking
Galvanized Grated
Steel Decking
Release of zinc into
the environment
Longer design life
$65,000
50 years
Fiberglass
Grated Decking
None identified
Longer design life,
low maintenance,
light weight, durable
$44,000
50 years
Floats
Float Tub
Thin cover around
flotation prone to
expose foam to
environment
Shorter design life
$36,000
30 years
Galvanized Steel
Filled with
Flotation
Release of zinc into
the environment
Longer design life
$125,000
35 years
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Design
Component
Alternatives
Water Quality
Impacts
Materials
Financial Sustainability
Cost
Design Life
Coated
Galvanized Steel
Filled with
Flotation
Can release zinc
into environment if
coating is abraded
Longer design life,
coating maintenance
due to abrasion
$220,000
50 years
Coated Steel
Filled with
Flotation
None identified
Longer design life,
coating maintenance
due to abrasion
$140,000
35 years
HDPE Pipe
Filled with
Flotation
None identified
Longer design life,
low maintenance
$75,000
50 years
NOTE: Alternatives analyses in this document use color coding to help identify the tradeoffs between alternatives. Green shading
represents an alternative that advances project goals, yellow represents neutral impact, and red represents an alternative that does not
advance goals. The highlighted row is the recommended alternative.
Alternative selection:
Frame
Float framing options include steel framed systems, which can be designed for commercial loading at a
moorage facility and have been used for a long time. Steel frames for the float system should be hot-
dip galvanized or coated to protect them from corrosion and provide a longer service life. The Port
recommends epoxy coating over galvanization due to concerns with zinc and comparable service life.
Decking
Any grating used should be suitable for ADA accessibility and have no greater than a half-inch gap.
From a sustainability perspective, the more open space in the grating, the more light penetration can
occur. Generally, grating with 60 percent or more open space is requested for use on floating docks to
provide environmental benefits. There are fiberglass gratings that provide both ADA accessibility and
have 60 percent or more open space. Steel grating could be used but adds significant weight to the
float system and would need to be galvanized or coated to provide corrosion and slip resistance. Since
no commercial operations are conducted on the float deck and heavy equipment is not used on the float
deck, fiberglass decking is recommended from both a sustainability and a life cycle cost perspective.
Floats
The floats will require flotation units that are fully encased. Four potential options include standard
manufactured float tubs, flotation with sprayed-applied coating, steel pipes or pontoons filled with
flotation, and High-Density Polyethylene (HDPE) pipes filled with flotation. Standard manufacturer
float tubs have relatively thin coverage around the flotation. HDPE pipes have a much thicker wall of
protection around the foam flotation. Steel pipes or pontoons would need to be protected from
corrosion with galvanizing or coatings. Given the heavy loads, potential for high impact and
commercial operations at the facility, and desire for sustainability to reduce zinc in the environment,
we recommend HDPE pipes filled with flotation are utilized as the flotation units for the float system.
NORTH PIER REPLACEMENT
Current system: treated timber pier
Infeasible replacement alternatives:
• Grating is not recommended as a feature due to heavy equipment use on pier
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• Composite piling not feasible structurally due to proposed loads and substrate conditions
• Reinhall piling not feasible due to substrate conditions
• Treated timber pile is not recommended due to environmental concerns
• Concrete piling is not recommended due to substrate conditions
• Uncoated steel deck is not feasible due to corrosion, aesthetics, and safety concerns
Feasible north pier replacement alternatives:
Design
Component
Alternative
Water Quality
Impacts
Materials
Financial Sustainability
Cost
Design Life
Deck
Concrete Deck
Consideration of
embodied carbon
Longer design life
$120,000
50 years
Coated
Galvanized
Steel Deck
Can release zinc into
environment if
coating is abraded
Longer design life,
coating maintenance
due to abrasion
$245,000
60 years
Galvanized
Steel Deck
Release of zinc into
the environment
Longer design life
$140,000
50 years
Piles
18” ½” Wall
Steel Pile
None identified
Needs to be replaced
quicker, wasting
more material
$136,000
25 years
18” 1” Wall
Steel Pile
Increases submerged
land impact
Increased design
life, but limited to
no availability
$272,000
50 years
18” ½” Wall
Steel Pile:
Galvanized
Release of zinc into
the environment
Longer design life
$144,000
45 years
18” ½” Wall
Steel Pile:
Epoxy-coated
None identified
Longer design life,
coating
maintenance due to
abrasion
$158,000
40 years
18” ½” Wall
Steel Pile:
Galvanized and
Epoxy-coated
Can release zinc into
environment if
coating is abraded
Longer design life,
coating maintenance
due to abrasion
$252,000
60 years
18” ½” Wall
Steel Pile:
Galvanized and
HDPE sleeve
Increases submerged
land impact, can
release zinc into
environment if
sleeve fails
Longer design life,
sleeve maintenance
$180,000
55 years
NOTE: Alternatives analyses in this document use color coding to help identify the tradeoffs between alternatives. Green shading
represents an alternative that advances project goals, yellow represents neutral impact, and red represents an alternative that does not
advance goals. The highlighted row is the recommended alternative.
Alternative selection:
Deck
A concrete deck is recommended for its sustainability, having a long service life and relatively inert
material properties once cured. Concrete pier decks are common and durable for the type of operations
at the facility. The solid concrete deck will also allow for collection and containment of stormwater
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runoff that could then be routed upland for treatment prior to discharge. To further improve the
sustainability of the project, the solid concrete deck can be precast concrete deck panels to minimize
overwater concrete work and construction time. Low embodied carbon concrete may be an option for
the pier deck depending on availability, schedule, and cost.
Piles
Potential pile types include different steel treatments. As discussed for the guide piling system, we
propose this project as a pilot to use epoxy-coated steel. Its life and condition will be assessed yearly.
This is a good location for a pilot since the piles are easily accessible for repair and maintenance
purposes.
OVERALL SUSTAINABILITY MEASURES
The following sustainability measures will be considered regardless of the alternatives listed above:
• Demolition and Disposal Plan
• Adherence to a Water Quality Control and Spill Control Plan
• Proper removal and disposal of all treated timber piling, timber pier structure, and other
demolition debris
• Consideration of coatings or sleeves for any steel or galvanized components
• Utilization of a fully grated deck for the new South Float System to maximize light penetration
• Maintenance or reduction of the overall footprint of the South Float System
• Addition of supplemental flotation to maintain wood waler system on North Float above water
• Utilization of vibratory hammer where feasible
• Require use of bubble curtain to reduce underwater noise if impact pile driving necessary
• Utilization of sustainable (low-embodied) concrete and concrete products
• Utilization of environmentally friendly sealants
• Utilization of stainless-steel utility hangers
• Limited use of treated timber
• Prioritize WMBE and local business use in contracting and material sourcing
• Prioritize locally sourced and recycled materials where possible
• Designed to be ADA compliant
• Design will accommodate the existing shore power system during float replacement
