COMMISSION 
AGENDA MEMORANDUM                        Item No.          6c 
ACTION ITEM                            Date of Meeting      October 23, 2018 
DATE:     October 12, 2018 
TO:        Stephen P. Metruck, Executive Director 
FROM:    Ralph Graves, Senior Director, Capital Development 
Janice Zahn, Assistant Engineering Director, Construction Services 
SUBJECT:  2018 Taxiway Improvement Projects  C800914 

Amount of contract change:            $700,000 
Total estimated project cost:         $47,500,000 

ACTION REQUESTED 
Request Commission authorization for the Executive Director to execute Change Order 23 to
Contract MC-0318750  for taxiway, runway, and apron improvements  at Seattle-Tacoma
International Airport for an amount not to exceed $700,000. No additional funds are being
requested. 
EXECUTIVE SUMMARY 
This project consists of taxiway, runway and apron modifications, reconfiguration, repairs and
relocation for safety and continued operational access by aircraft.  This project also includes
improvement to the industrial waste system and new taxiway signage. This project is driven by
the expansion of the North Satellite (NSAT) triggering the need to reconfigure the adjoining
Taxiways A & B (Alpha & Bravo). Due to the proximity of Taxiway L (Lima) to the Alpha/Bravo
work, the FAA required that Lima  be brought into compliance with current FAA design
standards by being relocated to minimize potential aircraft runway incursions. This relocation
requires a closure of Runway 16L/34R. This closure provides the opportunity to proceed with
fixing another safety concern at the intersection of Taxiway Q (Quebec) as well as needed
runway repairs. Based on the complexities of coordination, similar work, seasonal construction
limitations and runway use restrictions, it was decided that the many 2018 airfield work
projects  should  be  combined  into  a  single  airfield  contract  to  best  coordinate  airfield
construction phasing in the safest and most efficient manner. 
Currently this project is progressing into the last phase of construction as planned. The work at
Alpha and Quebec as well as the other airfield related projects are complete.  The work
adjacent to and on Runway 16L/34R, Bravo and Lima commenced on September 10, 2018 and
are projected to be complete in early December.

Template revised September 22, 2016.

COMMISSION AGENDA  Action Item No. 6c                                   Page 2 of 5 
Meeting Date: October 23, 2018 

During construction activities at Taxiway S (Sierra) and Runway 16L/34R, the pavement on
Sierra began to unravel. While initially a repair at the joint between Sierra and Runway 16L/34R 
was thought to be adequate, subsequent investigation of the pavement surfaces reveal more
widespread distress on Sierra. Sierra is the only asphalt taxiway on the airfield and was last
fully  paved  in  1990.   Sierra  is  currently  planned  to  be  resurfaced  in  the  2020  Airfield
Improvement Project.  Staff is recommending that Sierra be resurfaced immediately and an
Authorization of Critical Work was declared on October 5, 2018. A Change Order is required to
direct the Contractor to repair the taxiway. This Change Order will be issued for an amount not
to exceed $700,000. 
JUSTIFICATION 
The performance of this work requires the closure of Runway 16L/34R for the duration of the
repair. Currently Runway 16L/34R is closed due to the ongoing work on Bravo & Lima. The
resurfacing of Sierra can be accomplished without extending the current runway closure if we
have authorization to proceed. Without repairing this taxiway, it is unlikely that we could
return Sierra to service without severe Foreign Object Damage (FOD) risk to aircraft and would
likely result in the closure of Sierra until 2020. Currently, the only activity in the 2020 Airfield
Improvement Program that requires a runway closure is the Sierra resurfacing. Performing this
work now will eliminate a runway closure in 2020. 
DETAILS 
Background 
Sierra  is one of the oldest taxiways and the only asphalt taxiway on the airfield. While
historically it had been used very little, Sierra has recently become more heavily used to reduce
congestion at the South end of Runway 16L/34R due to increased activity at the South Satellite.
Sierra's pavement surface is almost 30 years old. FAA pavement standards for asphalt are
typically based on a 20 year life span. 
Due to the high volume of air operations it is highly desirable to reduce the number of runway
closures, especially Runway 16L/34R (the long runway).  There is a significant scheduling and
cost impact to the airlines resulting from closing this runway to perform work.  Staff has
estimated that the potential cost impact routes that require the longer runway is approximately
$50,000 per flight. Additionally in previous project memos, staff has detailed re-phasing the
current project from a summer project to a fall/winter project to ease congestion during the
busiest travel season. 



Template revised September 22, 2016; format updates October 19, 2016.

COMMISSION AGENDA  Action Item No. 6c                                   Page 3 of 5 
Meeting Date: October 23, 2018 
ALTERNATIVES AND IMPLICATIONS CONSIDERED 
Alternative 1  Perform a limited repair of Sierra 
Cost Implications: Approximate cost $200,000 - $300,000 
Pros: 
(1)   Low cost to the project. 
(2)   Resurfacing is currently planned in 2020 
Cons: 
(1)   FOD risk to the airfield would continue to exist from the unrepaired portions of the
taxiway. 
(2)   A closure of the 16L/34R Runway will be required in order to perform this work in
2020. This option has the highest operational impact. 
(3)   The combined cost of this option, plus resurfacing it again in 2020 makes it the highest
cost option. 
This is not the preferred alternative. 
Alternative 2  Close Sierra to traffic 
Cost Implications: Approximate cost $200,000
Pros: 
(1)   Lowest Cost 
(2)   Eliminates FOD risk. 
Cons: 
(1)   Sierra would not be usable, aircraft taxi routes would be modified contributing to
increased taxi time and congestion at the South end of the airfield 
This is not the preferred alternative. 
Alternative 3  Issue a Change Order with the current contractor to resurface Sierra 
Cost Implications: Approximate cost $700,000. 
Pros: 
(1)   Eliminates FOD risk. 
(2)   Keeps Sierra operational for the foreseeable future. 
(3)    Eliminates a future planned closure of Runway 16L/34R in 2020. 
Cons: 
(1)   There is a potential that FAA grant funding associated with this work in 2020 cannot
be recovered. 
This is the recommended alternative. 


Template revised September 22, 2016; format updates October 19, 2016.

COMMISSION AGENDA  Action Item No. 6c                                   Page 4 of 5 
Meeting Date: October 23, 2018 
FINANCIAL IMPLICATIONS 
There is no additional funding being requested in this memo.
ATTACHMENTS TO THIS REQUEST 
(1)   Presentation slides 
o  Slide 1  Airfield Photo Taxiway S 
o  Slide 2  Taxiway S Scope of Work 
(2) Critical Work Declaration, 10-5-2018 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
2018 Taxiway Improvement Projects 
November 14, 2017  The Commission authorized advertisement and execution of a single
major works construction contract comprised of the Taxiway A/B, Taxiway L/Q, 2018
Pavement Program, B Concourse IWS Upgrade, Taxiway H signage projects. 
Taxiways A/B/L/Q 
March 14, 2017  The Commission authorized design funds for construction documents for
Taxiways L and Q, to transfer budget and authorization from the NSAT project, and
approved use of PLA. 
May 24, 2016  The Commission authorized the NSAT increase of project scope and budget
that included Taxiway Lighting and Panel Replacement of $3.2M. 
2018 Pavement Replacement 
May 9, 2017  The Commission authorized design funds for construction documents for
replacement of distressed pavement and joint seal replacement in the 2018 portion of
the 2016-2020 Pavement Program, and approved use of PLA. 
October 25, 2016  The Commission authorized advertisement and execution of contract
for retrofits of 400 Hz In-ground power units and reconstruction of existing pavement at
Cargo 2. 
February 24, 2015  The Commission authorized design funds for construction documents
for replacement of distressed pavement and joint seal replacement in the 2016 portion
of the 2016-2020 Pavement Program. 
B Concourse IWS Upgrade 
October  25, 2016   The  Commission authorized capital spending for design and
construction of Port utility and supportive infrastructure work associated with the
Concourse B gate reconfiguration. 

Template revised September 22, 2016; format updates October 19, 2016.

COMMISSION AGENDA  Action Item No. 6c                                   Page 5 of 5 
Meeting Date: October 23, 2018 
Taxiway H Signage 
December 2, 2014  The Commission authorized advertisement and execution of the
Runway 16C/34C reconstruction that included the reconfiguration of Taxiway H. 

















Template revised September 22, 2016; format updates October 19, 2016.