PORT OF SEATTLE 
MEMORANDUM 
COMMISSION AGENDA               Item No.      4b 
ACTION ITEM 
Date of Meeting      May 6, 2014 
DATE:    April 29, 2014 
TO:      Tay Yoshitani, Chief Executive Officer 
FROM:   Darlene Robertson, Director, Harbor Services, Real Estate Division 
Tracy McKendry, Senior Manager, Recreational Boating Facilities 
Mark Longridge, Project Manager, Capital Development Division 
SUBJECT:  Shilshole Bay Marina Central Seawall Replacement (CIP #C800088) 
Amount of This Request:         $713,000   Source of Funds:     Existing Revenue
Bond Proceeds 
Est. Total Project Cost:           $915,000 
ACTION REQUESTED 
Request authorization for the Chief Executive Officer to (1) approve construction funding for the
rehabilitation of the central section of the Shilshole Bay Marina Seawall for an amount of 
$713,000 for a total project cost of $915,000 and (2) use Port crews in performance of the work.
SYNOPSIS 
The central section of the seawall, approximately 100', at Shilshole Bay Marina (SBM) was built
in 1962 as part of the original marina construction. It is at the end of its serviceable life. It is
currently the only section of the seawall composed of timber piers and lagging (other sections of
the seawall are concrete). This critical piece of timber infrastructure is over 50 years old and
existing lagging is showing signs of distress. Not addressing the condition could lead to failures
of the retaining structure and significant slope instability. Therefore, this section of the seawall
needs to be rehabilitated in order to maintain a valuable asset and continue operating a safe
facility for the public and our customers. With the Commission's previous approval of design
funds, various alternatives have been analyzed and the recommended construction method is to
rehabilitate the existing structure (further details follow). Port Construction Services will perform
this project using a combination of small works contracts and Port crews. 
Given the type of work to be done, and access to the work area, the construction schedule is
critical due to tidal fluctuations in Puget Sound and the requirement that the work be performed
while the tide is out. The summer tide windows are available in June, July, and August of this
year. Therefore, we would like to get Commission approval this month in order to proceed with
the work. While the work could be performed in the winter months, the needed negative tide
windows happen during this period only late at night or in the very early morning hours, both
complicating construction conditions, costs, and productivity due to weather and artificial
lighting requirements, and potential disruption to tenants and neighbors. 

Template revised May 30, 2013.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
April 29, 2014 
Page 2 of 5 
As this is a renewal/replacement project to rebuild existing, aged infrastructure, there are no
incremental revenues associated with this particular project. The funds being requested were
included in the 2014 Real Estate capital budget and Plan of Finance. 
BACKGROUND 
SBM was built in the late 1950's with the first dock opening in 1960. (SBM celebrated its 50th 
anniversary in 2012.) This section of the seawall was built in 1962 and was originally under the
central  pier  of  the  marina,  which  has  since  been  removed  as  part  of  the
redevelopment/replacement of the original docks completed in 2008. It is the only section of the
seawall composed of timber piers and lagging.  As mentioned, the existing lagging is showing
signs of distress and needs to be replaced or supplemented. This section of the seawall supports
the northern end of the central plaza and garden area of the marina and is heavily used by the
public. It is also the primary access point to both the fuel float/store and guest moorage slips of
the central docks, which are highly utilized by our tenants, the public, and other visitors to the
marina. Not replacing this section of the seawall could lead to localized failures of this retaining
structure and significant slope instability. 
The selected construction method to rehabilitate this section of the seawall is to replace the
existing timber lagging boards with either concrete panels or recycled plastic lumber boards and
place steel collars over the existing piles to hold these new lagging sections in place. 
Shilshole Bay Marina is the largest marina in Seattle providing more than 1,400 moorage slips,
approximately 80% of which are utilized by sailboats (current occupancy is approximately 98%).
The moorage provided is primarily for long-term recreational moorage with an additional 8,000
guest moorage visitors to the marina annually. The facility is used not only by recreational
vessel owners, both pleasure and commercial, but by commercial fishing and Tribal vessel
owners, along with the maritime businesses that support them. The vessel size ranges from small
kayaks to mega-yachts. 
The marina is an important job and revenue generator in Puget Sound's recreational boating
sector. It plays an important role by supplying a large amount of recreational moorage to the
Puget Sound region, by the economic impacts it generates, and by its annual positive cash flow
to the Port (Income from Operations) of over $5,600,000. From the Port of Seattle's 2009
Economic Impact Study (conducted by Martin Associates), the Port's recreational boating
marinas generated almost 400 jobs (direct, indirect & induced), almost $8,000,000 in local
purchases, $14,000,000 in business revenues and over $2,000,000 in state and local taxes, the
majority of which is from Shilshole Bay Marina. 
Recreational boaters spend money in various maritime service sectors such as navigational 
equipment, sails & sail making, engine services, marine repair, fuel, marine clothing, and many 
more. The recreational boating industry in the State of Washington is an approximately
$4 billion industry that created 1,923 jobs and generated $31,000,000 in state and local taxes 
(taken from the NW Marine Trade Association Economic Impact Study of Recreational Boating 
by Herbert Research dated April 2011).

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
April 29, 2014 
Page 3 of 5 
The overall value of Shilshole Bay Marina is estimated at $62,000,000. 
PROJECT JUSTIFICATION AND DETAILS 
Project Objectives 
Replace failing or weakened sections of the existing timber seawall. 
Extend the useable life of the central seawall for 30 to 50 years to match the redeveloped 
harbor/docks. 
Minimize disruption to the marina customers and available moorage during and after
construction. 
Scope of Work 
This project would complete the reconstruction of the remaining timber step wall section
(approximately 100 feet) of the Shilshole Bay Marina central seawall. The design calls for the
removal of the existing lagging and exposing of the existing timber piles, needed repair and
protection of the piles and placement of steel collars over the piling. Panelized concrete or
recycled plastic lumber lagging would then be placed between the piles to complete the
installation. 
Access to this work area, particularly the bottom step of the wall is extremely limited as it is at
an approximate tide elevation of zero mean higher high water. This allows for only certain shifts
to access and required the upmost flexibility in workforce to achieve the work. PCS will
perform this work with some work performed by small works contractors. 
By utilizing Port crews for this work we can not only take full advantage of the tide windows
available, but also allow for the uncertainty of site conditions behind the wall sections. While
soil sampling has been performed in this area the amount and extent of soil movement and
sloughing once excavated will be unknown until exposed. This approach provides the utmost
flexibility and control to adjust for not only tidal access but also customer, event and operational
needs onsite. 
Schedule 
This work has been delayed from its originally proposed schedule to take maximum advantage of
the summer tide windows available in June, July, and August 2014. Whi le the work could be
performed in the winter months these negative tide windows happen during late night or very
early morning hours, both complicating construction conditions, costs and productivity due to
weather and artificial lighting requirements, and potential disruption to tenants and neighbors. 
While the traditional window for in-water work would not open in this area until later in the
summer, the Port has requested an extension in this case to be allowed to perform the work while
the tide is out during these windows.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
April 29, 2014 
Page 4 of 5 
FINANCIAL IMPLICATIONS 
Budget/Authorization Summary              Capital     Expense   Total Project 
Original Budget                       $915,000          $0     $915,000 
Previous Authorizations                  $202,000          $0     $202,000 
Current request for authorization              $713,000          $0      $713,000 
Total Authorizations, including this request      $915,000          $0      $915,000 
Remaining budget to be authorized               $0          $0          $0 
Total Estimated Project Cost               $915,000          $0     $915,000 
Project Cost Breakdown                     This Request       Total Project 
Construction                                $625,000          $625,000 
Construction Management                      $32,000          $50,000 
Design                                     $0,000           $95,000 
Project Management                             $0          $71,000 
Permitting                                      $0           $18,000 
State & Local Taxes (estimated)                    $56,000           $56,000 
Total                                       $713,000           $915,000 
Budget Status and Source of Funds 
This project was included in the 2014 Real Estate capital budget and related Plan of Finance
under CIP #C800088 SBM Central Seawall Replacement in the amount of $915,000. The source
of funds will be existing 2007 revenue bond proceeds. 
Financial Analysis and Summary 
CIP Category             Renewal/Enhancement 
Project Type              Renewal & Replacement 
Risk adjusted discount rate     NA 
Key risk factors             Delay in start of project could impact the ability to
complete the work during the summer tide windows
which could increase project cost. 
Project cost for analysis        $915,000 
Business Unit (BU)          Harbor Services  Shilshole Bay Marina 
Effect on business performance  There is no incremental revenue associated with this
project as it is a renewal of needed infrastructure. 
This project will increase depreciation by $23K per year
based on a 40 year depreciable life, currently estimated by
engineering, and will reduce Net Operating Income by a
corresponding amount. 
IRR/NPV             The NPV is the present value of the project cost.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
April 29, 2014 
Page 5 of 5 
STRATEGIES AND OBJECTIVES 
This project provides for the continuation of a functioning facility to Port tenants in support of
business plan strategies and objectives that call for maintaining real estate assets and improving
the environment, not deferring maintenance, maintaining safe facilities and meeting our
customers' expectations. These strategies help to bolster the Port's Century Agenda strategies to
advance the region as a leading tourism destination and business gateway, and to support
enhancing the economic value of the maritime and fishing cluster.
ALTERNATIVES AND IMPLICATIONS CONSIDERED 
Alternative 1)  Do Nothing. Continue to monitor the current condition of the seawall piling
and lagging and repair as failures occur. These repairs would likely be significantly more
expensive approached individually, and may not be achievable based on tidal and permitting
restrictions which could lead to temporary closures of the plaza public areas and potential failure
of a larger section of the wall. This is not the recommended alternative. 
Alternative 2)  Replace the existing stepped timber seawall with a steel sheet pile wall. While
this option provides a long life, it is considerably more expensive and would present significant
access issues for placement of the pile under cantilevered sections of the pier and tying into each
end of the existing seawall. This is not the recommended alternative. 
Alternative 3)  Encase the existing seawall under a layer of riprap and gravel. While this
alternative provides a long life at lower cost, the current slope of the seawall would not allow for
this installation at an acceptable slope without impacting the existing floats. The required slopes
for this alternative would make the floats ground at extreme low tides without modification of
the existing float layout. This is not the recommended alternative. 
Alternative 4)  Rebuild the existing seawall using long-life materials. Remove the existing
lagging and expose the existing timber piles, repair and protection of the piles and placement of
steel collars over the piling. Use concrete or recycled plastic lumber lagging placed between the
piles to complete the installation. This option offers a balance of cost effectiveness and long life,
along with easy site accessibility. It allows the wall to maintain its existing geometry while
strengthening it and extending its life. This is the recommended alternative. 
ATTACHMENTS TO THIS REQUEST 
Existing condition and aerial view site photographs. 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
July 9, 2013  The Commission authorized design for the rehabilitation of 100' of the
Shilshole Bay Marina Central Seawall for $202,000.