COMMISSION 
AGENDA MEMORANDUM                        Item No.          8j 
ACTION ITEM                            Date of Meeting      August 10, 2021 

DATE:     August 2, 2021 
TO:        Stephen P. Metruck, Executive Director 
FROM:    Eileen Francisco, Acting Director, Aviation Facilities and Capital Programs 
Wayne Grotheer, Director, Aviation Project Management 
SUBJECT:  Airfield  Pavement  and   Supporting  Infrastructure  Replacement  Program 
(CIP #C800930) - North Runway Protection Zone Culvert 
Amount of this request:               $3,800,000 
Total estimated project cost:        $153,500,000 
ACTION REQUESTED 
Request Commission authorization for the Executive Director to advertise and award a major
public works contract to replace the North Runway Protection Zone Culvert (NRPZ Culvert), a
year 2022 component of the 2021 to 2025 Airfield Pavement and Supporting Infrastructure
Replacement Program. This construction authorization is for $3,800,000 for a total program
authorization to date of $55,195,000. The total 2021-2025 program cost is $153,500,000. 
EXECUTIVE SUMMARY 
This project will replace the existing failing culverts and the road crossing at Miller Creek on
South 150th St. with an engineered structure capable of sustaining heavy vehicle loading
requirements. The new structure will also revert  the creek at this location to a natural
streambed and restore fish passage. The primary reason to maintain this road is that it provides
access for Aircraft Rescue and Fire Fighting (ARFF) vehicles to be able to respond to any incident
within the Runway Protection Zone (RPZ) north of the airport. The road has a variety of
additional uses, including as a haul road for staging and moving construction material for ongoing
projects, Port Police, security access, and environmental resource staff accessing the
wetlands and creek. The existing culverts under the road have settled to the point where the
culverts are now located beneath the Miller Creek streambed and therefore have restricted
creek flow and fish passage. Additionally, sinkholes have developed in the roadway that crosses
Miller Creek, creating concerns about stability of the roadbed and the potential for safety
hazards. This project has received all the Environmental permits required to do work in this
wetland area. 
This project was included in the 2021-2025 capital plan and the funding source will be the
Airport Development Fund. 

Template revised January 10, 2019.

COMMISSION AGENDA  Action Item No. __8j__                               Page 2 of 6 
Meeting Date: August 10, 2021 

JUSTIFICATION 
In its current state the existing culvert blocks Miller Creek, does not provide fish passage, and 
the failed roadway above creates an unsafe environment for all users of the roadway. It may
also limit ARFF response to any incident within the north RPZ. ARFF access to the RPZ is an FAA
requirement.  This project will replace the existing failing culverts and the road crossing Miller
Creek on S. 150th St. with an engineered structure spanning the creek, revert the creek to a
natural streambed at this location, and restore fish passage. 
Diversity in Contracting 
The project staff, in coordination with the Diversity in Contracting Department, have set a 10%
woman and minority business enterprise (WMBE) aspirational goal for the NRPZ culvert project. 
The goal is based upon the project's scopes of work which does not include FAA funding, and
baseline availability of certified WMBE businesses to perform the work. 
Details 
The overall purpose of this project is to provide safe conditions for ARFF, construction, and
other users on the access road within the North Runway Protection Zone road and to reopen
the fish passage in the wetlands. This project was one of the planned components of the 2021-
2025 Airfield Pavement and Supporting Infrastructure Program. Design authorization for the
overall program occurred in October 2019 while construction authorization is brought forth for
each yearly construction contract or component. Construction of the culvert replacement will
occur in the summer of 2022 during the permissible fish window of July to October while
stream flow conditions are at their lowest level. Concurrence for this project and the in-water
work permits have been obtained from the Washington Department of Fish and Wildlife 
(WDFW) and the Army Corps of Engineers (Corps). 
Scope of Work 
The scope for work for this project includes: 
Install temporary stream bypass, water treatment and fish protection measures 
Remove the failing roadway 
Restore the Miller Creek streambed to its natural state 
Install piling for the new roadway structure span 
Install the engineered roadway decking spanning the creek 
Schedule 
Activity 
Construction start                             2022 Quarter 3 
In-use date                                    2022 Quarter 4 

Template revised June 27, 2019 (Diversity in Contracting).

COMMISSION AGENDA  Action Item No. __8j__                               Page 3 of 6 
Meeting Date: August 10, 2021 
Cost Breakdown                                     This Request           Total Project 
Design                                                           $0            $13,495,000 
Construction                                             $3,800,000          $140,005,000 
Total                                                         $3,800,000           $153,500,000 
ALTERNATIVES AND IMPLICATIONS CONSIDERED 
Alternative 1  Shut the road down permanently and do not restore fish passage 
Cost Implications: $600,000 expense funds for design costs to date 
Pros: 
(1)   No construction costs 
(2)   No disturbance to the wetlands 
Cons: 
(1)   ARFF vehicles will no longer have access to the north RPZ to be able to respond to an
aircraft incident, which is an FAA requirement. Police, security, and environmental
staff will also lose this access. Construction vehicles accessing the airfield from SR518
and SR509 will also need to use surface streets. 
(2)   Fish passage is not restored 
(3)   Not supportive of current agreements with the Corps and WDFW. 
This is not the recommended alternative. 
Alternative 2  Continue to perform ad-hoc repairs to the access road 
Cost Implications: $600,000 expense funds for design costs to date; and $50,000 per year in
repairs 
Pros: 
(1)   Lower initial costs 
Cons: 
(1)   Not an engineered solution. Roadway could collapse at any time restricting ARFF
access to the north Runway Protection Zone and other road uses. 
(2)   Delay pushes full replacement into a future date, escalating actual replacement costs 
(3)   Fish passage is not restored 
(4)   Not supportive of current agreements with the Corps and WDFW. 
This is not the recommended alternative. 
Alternative 3  Replace the culvert with an engineered structure and restore creek and fish
passage 
Cost Implications: $4,900,000 
Pros: 
(1)   Fish passage will be restored 

Template revised June 27, 2019 (Diversity in Contracting).

COMMISSION AGENDA  Action Item No. __8j__                               Page 4 of 6 
Meeting Date: August 10, 2021 
(2)   Safe road conditions for ARFF and construction vehicles 
(3)   Supports agreements with the Corps and WDFW. 
Cons: 
(1)   Highest initial capital costs 
(2)   Temporary closure of the access road 
(3)   Temporary disturbance of the wetlands 
This is the recommended alternative. 
FINANCIAL IMPLICATIONS 
The 2021-2025 Airfield Pavement and Supporting Infrastructure Replacement Program is
included in the annual FAA Airport Capital Improvement Program (ACIP) letter for FAA Airport
Improvement Program (AIP) Grant funding. The program will receive federal grant funding for
eligible items meeting the FAA standards and the anticipated FAA grant reimbursement over
the life of the program is $47,992,000 with $21,206,057 received for the year 2021. 
Cost Estimate/Authorization Summary              Capital        Expense           Total 
COST ESTIMATE 
Original estimate                               $156,300,000               $0   $156,300,000 
Previous changes  net                          (2,800,000)                0      (2,800,000) 
Revised estimate                               153,500,000                0     153,500,000 
AUTHORIZATION 
Previous authorizations                          51,395,000                0      51,395,000 
Current request for authorization                  3,800,000                0       3,800,000 
Total authorizations, including this request       55,195,000                0      55,195,000 
Remaining amount to be authorized           $98,305,000             $0    $98,305,000 
Annual Budget Status and Source of Funds 
This project, C800930 Airfield Pavement and Supporting infrastructure Replacement Program, 
was included in the 2021-2025  capital budget and plan of finance with a budget of
$153,500,000. A budget reduction of $2,800,000 was transferred to the Airfield Pavement
Program 2016-2020 (C800483) to accelerate pavement and supporting infrastructure work to
take advantage of the lower operations in 2020. There was zero net change to the Aviation
capital budget. This project has a Majority-In-Interest approval from the airlines in January
2020. The funding sources will be the Airport Development Fund, AIP grants, and revenue
bonds. 



Template revised June 27, 2019 (Diversity in Contracting).

COMMISSION AGENDA  Action Item No. __8j__                               Page 5 of 6 
Meeting Date: August 10, 2021 
Financial Analysis and Summary 
Project cost for analysis 
$153,500,000 
Business Unit (BU)                            Airfield movement and airfield apron 
Effect on business performance (NOI after    NOI after depreciation will increase due to
depreciation)                                 inclusion of capital (and operating) costs in
airline rate base 
IRR/NPV (if relevant)                           N/A 
CPE Impact                                 Total project cost CPE of 0.38 in 2026; annual
CPE of .05 
Future Revenues and Expenses (Total cost of ownership) 
This project will not have an impact on annual Aviation Maintenance operating & maintenance
(O&M) costs and may lead to a reduction in the amount of time currently spent by the field
crew on repairing this section of the road due to the current condition of the road. After
implementing the project, it is anticipated that many of the problems that we currently have in
this area would be resolved.
Anticipate approximately $50,000 ($10,000 annually) to conduct five years of post-construction 
performance monitoring as specified by the Washington Department of Fish and Wildlife
(WDFW) and the Army Corps of Engineers (Corps).
ADDITIONAL BACKGROUND 
The ARFF Access Road and the culvert over Miller Creek were constructed in 1983. The
geotechnical investigation study conducted in fall of 2018 indicated the presence of soft peat
layers in the subsurface. It is anticipated that the culvert and the road east of the culvert may
have suffered significant settlement due to this peat layer. Using a new precast structure and
building a new foundation supported on king piles are needed to prevent settlement of the new
structure in the future. 
ATTACHMENTS TO THIS REQUEST 
Presentation slides 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
November 10, 2020  The Commission authorized the Executive Director to (1)
advertise and execute a major works construction contract and (2) include a project
labor agreement for the replacement of distressed pavements and supporting
infrastructure  for  the  2021  portion  of  the  2021-2025  Airfield  Pavement  and
Supporting Infrastructure Replacement Program at the Seattle-Tacoma International

Template revised June 27, 2019 (Diversity in Contracting).

COMMISSION AGENDA  Action Item No. __8j__                               Page 6 of 6 
Meeting Date: August 10, 2021 
Airport. This construction authorization is for $37,900,000 for a total authorization
to date of $51,395,000. The total 2021-2025 program cost is $153,500,000. 
October 22, 2019  The Commission authorized the Executive Director to authorize
design and preparation of construction documents for the 2021-2025 Airfield
Pavement and Supporting Infrastructure Replacement Projects at the Seattle-
Tacoma International Airport in the amount of $16,000,000 and approve the use of a
project labor agreement (PLA) for each year's construction contract. 















Template revised June 27, 2019 (Diversity in Contracting).