
COMMISSION AGENDA – Briefing Item No. 7a Page 2 of 3
Meeting Date: May 8, 2018
Template revised September 22, 2016.
ADDITIONAL BACKGROUND
The primary purpose of the SAMP is to identify facility improvements required to satisfy
demand over the 20-year planning horizon and to balance capacity in all key functional areas to
the fixed capacity of the airfield. To that end, the SAMP started with a 20-year, market demand
of cargo and passenger activity which was used to determine peak hour facility requirements
based on demand derived from the movement of aircraft, passengers, bags, vehicles and
freight. Alternatives for facilities development to satisfy demand were then developed and
assessed, resulting in a phased capital program to deliver needed capacity through the 20-year
planning horizon.
For planning purposes, the SAMP assumes the airport’s current three-runway system and close-
in airspace configuration will remain in place. With the airport’s small footprint and significant
physical constraints, redevelopment at Sea-Tac requires expensive relocation of existing
facilities and limited options for expansion.
Work to evaluate alternatives for project phasing and to assess airside capacity has included
extensive airside modeling in consultation with FAA specialists and has determined that existing
constraints require a two-step approach to advance the SAMP.
The first step was to identify a package of near-term projects to be assessed through
environmental review. Airside modeling of these Near-Term projects (including 19 gates
connected to a second terminal, north of the existing terminal complex) has confirmed that
they will deliver needed capacity through 2027 and balance capacity in all key functional areas
to the fixed capacity of the airfield and existing airspace. Staff has also concluded that with
sound financial planning, the package of near-term projects is affordable.
The second step is to better understand the constraints for airside facilities at Sea-Tac, which
include runway and taxiway utilization, gate availability, airspace management as conducted by
FAA, and affordability. The Port will work with the FAA to conduct an airfield/airspace study
which will determine the long-term capacity of the airfield and inform or reaffirm the SAMP
long-term vision.
Following the completion of the SAMP Planning Phase 1 process and the identification of the
Near-Term projects, the FAA and the Port of Seattle are required to evaluate the potential
impacts of the identified projects under NEPA and SEPA. The environmental review process is
expected to take 12 – 18 months. The environmental review process will include coordination
with the FAA, agency and public environmental scoping, a robust environmental evaluation
identifying potential environmental impacts, an agency and public comment process associated
with the findings of the environmental evaluation, and an approval of the environmental
document by the FAA and the Port of Seattle.