P.O. Box 1209 
P.O. Box 1209 
Seattle, WA 98111-1209 
Seattle, WA 98111-1209 
Tel: 787-3000 
Tel: 787-3000 
www.portseattle.org 
www.portseattle.org 
SUSTAINABLE DESIGN APPROACH / SUSTAINABLE DESIGN STRATEGY 
HARBOR 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.





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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. 
• SupportLocal E      conomic 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      $60,000     25 years 
quicker, wasting more
material 
12” ½” Wall Steel Pile:   Release of zinc into the        Longer design life        $66,000     45 years 
Galvanized              environment 
12” ½” Wall Steel       None identified              Longer design life,      $77,000    35 years 
Pile: Epoxy-coated                                   coating maintenance
due to abrasion 
12” ½” Wall Steel Pile:   Can release zinc into           Longer design life,       $165,000   60 years 
Galvanized and Epoxy-  environment if coating is      coating maintenance
coated                    abraded                        due to abrasion 
12” ½” Wall Steel Pile:   Increases submerged land      Longer design life,       $99,000     55 years 
Galvanized and HDPE   impact, can release zinc into   sleeve maintenance 
Sleeve                   environment if sleeve fails 
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, longterm
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       Alternatives       Water Quality         Materials        Financial Sustainability 
Component                       Impacts                            Cost     Design Life 
Frame       Galvanized Steel   Release of zinc into  Longer design life      $95,000    45 years 
Frame              the environment 
Steel Frame with   None identified      Longer design life,     $110,000   35 years 
Epoxy Coating                       coating maintenance
due to abrasion 
Galvanized Steel    Can release zinc      Longer design life,      $190,000   60 years 
Frame with Epoxy  into environment if   coating maintenance
Coating             coating is abraded     due to abrasion 
Decking      Galvanized Grated  Release of zinc into  Longer design life       $65,000    50 years 
Steel Decking       the environment 
Fiberglass         None identified      Longer design life,     $44,000    50 years 
Grated Decking                       low maintenance,
light weight, durable 
Floats         Float Tub            Thin cover around    Shorter design life       $36,000    30 years 
flotation prone to
expose foam to
environment 
Galvanized Steel    Release of zinc into   Longer design life       $125,000   35 years 
Filled with           the environment
Flotation 

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              Design       Alternatives       Water Quality         Materials        Financial Sustainability 
Component                       Impacts                            Cost     Design Life 
Coated            Can release zinc     Longer design life,      $220,000  50 years 
Galvanized Steel    into environment if   coating maintenance
Filled with           coating is abraded     due to abrasion 
Flotation 
Coated Steel        None identified       Longer design life,      $140,000   35 years 
Filled with                                 coating maintenance
Flotation                                     due to abrasion 
HDPE Pipe       None identified     Longer design life,    $75,000    50 years 
Filled with                               low maintenance 
Flotation 
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 hotdip
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       Alternative       Water Quality         Materials       Financial Sustainability 
Component                       Impacts                           Cost     Design Life 
Deck           Concrete Deck  Consideration of     Longer design life    $120,000    50 years 
embodied carbon 
Coated          Can release zinc into  Longer design life,    $245,000    60 years 
Galvanized       environment if        coating maintenance
Steel Deck        coating is abraded     due to abrasion 
Galvanized       Release of zinc into   Longer design life     $140,000    50 years 
Steel Deck        the environment 
Piles              18” ½” Wall      None identified         Needs to be replaced   $136,000     25 years 
Steel Pile                                    quicker, wasting
more material 
18” 1” Wall      Increases submerged  Increased design      $272,000    50 years 
Steel Pile          land impact             life, but limited to
no availability 
18” ½” Wall     Release of zinc into   Longer design life     $144,000    45 years 
Steel Pile:         the environment
Galvanized 
18” ½” Wall     None identified      Longer design life,   $158,000    40 years 
Steel Pile:                                 coating
Epoxy-coated                        maintenance due to
abrasion 
18” ½” Wall     Can release zinc into  Longer design life,    $252,000    60 years 
Steel Pile:         environment if         coating maintenance
Galvanized and   coating is abraded     due to abrasion
Epoxy-coated 
18” ½” Wall     Increases submerged  Longer design life,    $180,000    55 years 
Steel Pile:         land impact, can        sleeve maintenance 
Galvanized and   release zinc into
HDPE sleeve     environment if
sleeve fails 
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






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