PORT OF SEATTLE 
MEMORANDUM 
COMMISSION AGENDA               Item No.      5d 
ACTION ITEM 
Date of Meeting     January 7, 2014 
DATE:    December 12, 2013 
TO:      Tay Yoshitani, Chief Executive Officer 
FROM:   David Soike, Director, Aviation Facilities and Capital Programs 
Robert York, Senior Engineer, Aviation Facilities and Infrastructure 
SUBJECT:  Stormwater Pipe Replacement on Town and Country site south of the Airport 
(C800651) 
Amount of This Request:         $350,000   Source of Funds:   Airport Development
Fund 
Est. Total Project Cost:           $350,000 
Est. State and Local Taxes:         $10,100 
ACTION REQUESTED 
Request Commission authorization for the Chief Executive Officer to authorize (1) purchase of
necessary materials and supplies, and (2) utilization of Port crews to install a storm water pipe in
the former Town and Country site south of the Seattle-Tacoma International Airport in an
amount not to exceed $350,000.
SYNOPSIS 
The Port agreed with local agencies to replace the most severely deteriorated section(s) of a large
storm drainage pipe located on Port-owned property south of Seattle-Tacoma International
Airport. The property was formerly the Town and Country mobile home park site. An initial
project budget was developed that indicated that the work could be completed as a small works
project; however, continued cave-ins have expanded the scope of the project to include
additional length of pipe, including a small section across the property line into the adjacent
Washington State Department of Transportation (WSDOT) owned property. In addition, as the
project began, permit approvals both from the City of SeaTac and from WSDOT, as well as 
coordination with Midway Sewer District became necessary. Construction will need to occur
during the most difficult construction season, requiring detaining and possibly bypassing storm
water during construction. These issues caused the project scope and budget to expand to a level
requiring Commission approval. 
The Commission was notified of the Critical Work determination and budget increase during the
December 10, 2013, Commission meeting.

Template revised May 30, 2013.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
December 12, 2013 
Page 2 of 4 

BACKGROUND 
Over the years, as part of noise mitigation projects, the Port has purchased numerous parcels, 
including the former Town and Country Trailer Court located south of Seattle-Tacoma
International Airport. A decades-old 36- to 48-inch diameter storm drain pipe, which conveyed
off-site drainage throughout this property, had been previously constructed on the property
before the Port assumed ownership. This corrugated metal pipe is now severely deteriorated and
is failing in places, causing cave-ins and allowing sediment to be carried downstream to storm
water infrastructure owned by the City of SeaTac.
After discussions with the City, the Port assumed responsibility for replacing the most
deteriorated section of existing pipe with new 36-inch diameter, smooth inner wall, corrugated
high density polyethylene pipe.  Approximately 550 feet of new pipe and manhole(s) are
proposed to be installed. 
PROJECT JUSTIFICATION AND DETAILS 
The project is deemed necessary to be completed as soon as possible because the situation has
worsened to the point where delaying this work until drier months would cause further
sedimentation.  Further delay may eventually compromise the ability of the existing
infrastructure to convey the storm water through Port property. 
Project Objectives 
Replace failed and failing infrastructure 
Maintain good community relations 
Scope of Work 
Install new pipe and related infrastructure 
Restore areas where existing cave-ins have occurred 
Schedule 
Work is expected to be substantially complete by February 28, 2014 
FINANCIAL IMPLICATIONS 
Budget/Authorization Summary              Capital     Expense   Total Project 
Original Budget                       $250,000          $0     $250,000 
Budget increase                        $100,000                $100,000 
Revised budget                       $350,000                $350,000 
Previous Authorizations                       $0          $0          $0 
Current request for authorization              $350,000          $0      $350,000 
Total Authorizations, including this request      $350,000          $0      $350,000

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
December 12, 2013 
Page 3 of 4 
Remaining budget to be authorized               $0          $0          $0 
Total Estimated Project Cost               $350,000          $0     $350,000 
Project Cost Breakdown                     This Request       Total Project 
Construction                                $292,000          $292,000 
Construction Management                       $5,900           $5,900 
Design                                    $15,000           $15,000 
Project Management                          $10,000          $10,000 
Permitting                                    $7,000            $7,000 
State & Local Taxes (estimated)                    $10,100           $10,100 
Total                                       $350,000           $350,000 
Budget Status and Source of Funds 
This project was budgeted for 2014 within the Small Jobs project budget (CIP C800017) that
serves to fund smaller sized and fast paced projects similar to this one. Due to the budget
increase, this project will now be performed within a new CIP, C800651. The budget for this
new CIP will be transferred from the Aeronautical Allowance CIP (C800404), resulting in no net
change to the total Aviation capital budget. The project is funded by the Airport Development
Fund.

Financial Analysis and Summary 
CIP Category             Renewal and Enhancement 
Project Type              Renewal and Replacement 
Risk adjusted discount rate     N/A 
Key risk factors             N/A 
Project cost for analysis        $350,000 
Business Unit (BU)          Airfield Movement Area (Noise property) 
Effect on business performance  NOI after depreciation will increase 
IRR/NPV             N/A 
CPE Impact             Less than $.01 in 2015 
Lifecycle Cost and Savings 
Only the most deteriorated section of pipe would be replaced at this time. Discussions with the
City of SeaTac and WSDOT will continue regarding responsibility, timing, and need for
replacing other portions the storm drainage conveyance system. A State of Washington funded
transportation package would likely negate the need for the Airport to replace other portions of
the pipe, since it would be replaced as part of either state funded City roadways or as part of SR-
509 construction.
The new piping system that would be used is one of the most cost-effective selections for this
application. The new pipe would have less friction loss and therefore can be a smaller diameter

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
December 12, 2013 
Page 4 of 4 
than the existing pipe. The new piping system is being designed for a minimum 50-year life
expectancy and would have a partially diagonal alignment, slightly reducing the required length
of pipe. 
STRATEGIES AND OBJECTIVES 
This project supports the Port's Century Agenda objective to "Be the greenest, and most energy
efficient port in North America" by meeting or exceeding agency requirementsfor storm water
leaving Port-owned or operated facilities. 
ALTERNATIVES AND IMPLICATIONS CONSIDERED 
Alternative 1)  Do nothing. This would result in continued failure of the existing pipe, creating
additional risk of flooding, sedimentation, or erosion and possible enforcement action by the City
of SeaTac. This is not the recommended alternative. 
Alternative 2)  Replace the entire piping system within Port property. This alternative would
be 2 to 3 times more expensive than a limited replacement of the existing piping. Portions of the
piping system have deteriorated but have not yet caved in. These sections of pipe were judged to
not need immediate replacement.  In addition, the property is being considered for future
redevelopment for both the extension of SR-509 and the City's South 28th Street extension.
Ongoing coordination with these agencies may later result in portions of the existing stormwater
conveyance system being modified by future City or State redevelopment. This is not the
recommended alternative.
Alternative 3)  Replacement of only the most deteriorated sections of pipe. This is the
recommended alternative. 
ATTACHMENTS TO THIS REQUEST 
None 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
None