Item No:     6c_attach_c
Date of Meeting: October 25, 2016
Port ....... .,                                   P.O. Box 1209
Seattle, WA 98111-1209
Tel: (206) 728-3000
of Seattle
www.portseattle.org

Final State Environmental Policy Act (SEPA)
Mitigated Determination of Non-Significance (MONS) of Proposed Action for
Seattle-Tacoma International Airport (Sea-Tac Airport)
Flight Corridor Safety Program - Phase 1
The Port of Seattle has completed an environmental analysis, including review of pertinent and
available environmental information and preparation of an Environmental Checklist for the
following proposal:
Description and Clarification of Proposal: The Port of Seattle is proposing to remove
obstructions consisting of trees and other vegetation at and around Seattle-Tacoma International
Airport. Removal of the obstructions will ensure the Airport complies with Federal Aviation
Administration (FAA) regulations that require airport operators to protect flight operations into
and out of the airport and assure that objects obstructing aircraft approach and departure areas
are removed.
This SEPA determination is for Phase 1 located on Port of Seattle property only. Additional
SEPA review will be required for Phases 2 and 3 and will include public and agency outreach
and comment periods.
The Flight Corridor Safety Program will remove a total of approximately 2,750 trees and is
planned to be accomplished in three phases over the next three years ending in 2019. Phase 1,
expected to begin in the fourth quarter of 2016, will include the removal ofobstructions on Portowned
properties, Phase 2 will include the removal of obstructions on commercial and public
properties, and Phase 3 will include the removal of obstructions on private properties.
Phase 1 will remove approximately 1,170 trees located on 27 acres of Port of Seattle property.
After the removal of these obstructions, new trees and vegetation will be re-planted in
accordance with federal, state, and local requirements and Port of Seattle policy. Mitigation for
Phase 1 includes:
Re-planting of approximately 4,000 trees (updated based on project design) for the
removal of approximately 1,170 trees;
Shrubs and hydro seeding to revegetate areas where ground vegetation or understory
impacts occur;
Erosion control best practices;
Removal of trees outside of the bird-nesting season;
Construction design and specifications that require the avoidance of ground disturbing
activities inside wetlands; and
POS SEPA No. 16-07
Flight Corridor Safety Program - Phase 1
Page 1 of 4

I'OS SEPA No. 16-07
Flight Corridor Safety Program  Phase 1
Page 2 of4

- A monitoring period of 5 years (updated based on project design) within wetland and
buffer areas.

Location of Proposal: Phase 1 has six project sites located at and around Seattle-Tacoma
International Airport. The airport address is 17801 Pacic Highway South, Seattle, Washington,
98158. These sites include:

0  Site 1 (P-l) - Located immediately north ofSouth 154'h Street and Runway 16R/34L and
south of State Route 518
0  Site 2 (P-2) - Located immediately west and adjacent runway 16R/34L and P011 ofSeattle's
West Side Ofces
0  Site 3a (P3a) - Located directly south of runway 16C/34C and S 188'h Street surrounding
the north and east edges of lagoon 3 (Le. Port of Seattle's stormwater storage)
0  Site 3b (P3b) - Located directly south of runway 16C/34C and S 188lh Street surrounding
the north and east edges of lagoon 3
a  Site 4 (P-4) - Located south of the airport and south of Site P-3a and Site P-6, southwest of
Site P-3b, west ofthe runway 16L/34R ALSF, and intersected by S 200lh Street
I  Site 5 (P-S) - Located south of runway 16C/34C, directly south of S 200'h Street, and west
of Site P-4
- Site 6 (P-6) - Located west of Site P-3b and runway l6L/34R Approach Lighting System
with Sequence Flashers (ALSF) and south of Site P-3a

Lead Agency: Port ofSeattle (SEPA No. 16-07)

Determination: The Port of Seattle has determined that this proposal would have likely
signicant adverse environmental impacts that would require the preparation of an EIS, but that
those likely impacts have been reduced down to a nonsignieant level as a result of the proposed
Mitigation for Phase I which is described above. See WAC 1971 1-350. As a result of the
proposed Mitigation for Phase I, this proposal will not have a probable signicant adverse
impact on the environment and a MDNS is an appropriate threshold determination. Accordingly,
an environmental impact statement (EIS) is not required under the provisions of the Washington
State Environmental Policy Act (Chapter 43.21 RCW, Chapter 197-1 1 WAC) and Port of Seattle
SEPA Policies and Procedures (Port Commission Resolution 3650). This decision was made
after review of a completed environmental checklist, comments by the public and other entities,
and other information that is available upon request.

Supporting Information: Information used to reach this determination, and applicable State
laws and Port of Seattle policies, regulations, and procedures are available for public review at
the Port of Seattle ofce, Environment and Sustainability Department, Pier 69, 271 1 Alaskan
Way, Seattle, Washington, and Seattle-Tacoma International Airport, Airport Ofce Building
reception, 17801 International Boulevard, Seattle, Washington. The document is also available
for review on line at htt ://www. Oitseattleor Environmental/Environmcntal- 
Documents/SEPA-NEPA/Pages/defaultaspx and additional information at the Flight Corridor
Safety Program website at: htt ://www. ortseattleor /Busmess/Construction-Projects/Airport 
l'roiects/I'ages/safe corridoraspx .

POS SEPA No. 16-07
Flight Corridor Safety Program  Phase I
Page 3 of 4

Public & Agency Comment: The MDNS and Environmental Checklist for this project were
circulated on July 15, 2016, and the comment period ended August 5, 2016. Four comments
were received by email through the Port of Seattle's SEPA public and agency comment process.
The description of the project proposal and proposed Mitigation for Phase I was updated to
provide clarication in response to the comments received and to more specically describe the
mitigation that would be proposed for the proposal. The Port of Seattle has concluded that no
likely significant adverse environmental effects will result from the proposed Flight Corridor
Safety Program - Phase 1. The Port of Seattle's Final MDNS is being issued, as of August 26,
2016, based on the nal mitigated detemtination of no signicant environmental impacts.

Appeals: The Port of Seattle's decision on the proposal described above and the Port's issuance
of a Final MDNS on this proposal constitute the Port of Seattle's nal SEPA decision. This
SEPA MDNS determination may be appealed by ling an application for a writ of review in
King County Superior Court within twenty-one (21) days of the date below pursuant to Port of
Seattle Resolution No. 3650 and RCW 43.210075.

Responsible Ofcial:     Elizabeth Leavitt
Position/Title:          Senior Director, Environment and Sustainability, Port of Seattle
Address:            Pier 69
PO. Box 1209
Seattle, WA 981 1 1
(L                    0/90/10
SEPA Responsible Ofcial                        August 26, 2016
Port of Seattle                                     Date of Final MDNS





Translations help for non-English speaking neighbors of Sea-Tac Airport

If you need assistance or want to receive a response to a question in your native language, please
call the Port's language help line:

0  Para espaol, llame al (206)787-3797 y marque 1.

o  B' su' dung ti'ng Vit, goi 56 (206) 787-3797 Va nha'n phim 2

- Soomaali, wac (206) 787-3797, kadib riix 3.

- mLtm'Jmnnig: qutugmgamme (206) 787-3797 umqmma 4:

o  For other languages, call (206) 787-3797 and press 5.

PCS SEPA No. 16-07
Flight Corridor Safety Program  Phase 1
Page 4 of 4

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