of Seattle

MEMORANDUM

Item No.:          7b

4
Date of Meeting:  October 20 2009


DATE:       October 15, 2009

TO:     Tay Yoshitani, Chief Executive Officer

FROM:   Ralph Graves, Managing Director, Capital Develo ment Division 2410
Ray Rawe, Director, Engineering Services 246 Epr 12R

Ref:  (a) RCW 39.04.020 and RCW 39.04.280
(b) Port of Seattle Resolution 3605, Para. 4.2.3.6

SUBJECT: DECLARATION OF EMERGENCY

The purpose of this memorandum is to inform Commission in accordance with Resolution 3605,
Section 4.2.3.6, that an emergency was declared on October 15, 2009 to provide back-up
power
generator capabilities at Seattle-Tacoma International Airport (STLA).

The Howard Hanson Dam, which is owned by the United States Army Corps of Engineers
(USACE) is the primary ood protection facility for all of the lower Green River Valley.
Following a record high level of water behind Howard Hanson Dam in January 2009, the Corps
discovered two depressions on the right abutment adjacent to the dam. The USACE is currently
assessing the damage to the right abutment and has determined that until the assessment is
completed, the Corps will reduce the amount of water that it will allow to be stored behind the
dam in order to protect the integrity of the dam. Potential impacts of the restrictions on the ood
storage capacity are increased ood risk to the Green River Valley below the dam. According to
the Corps, the increased ood risk to the Green River Valley will persist during the normal
October through April rain period over the next 3 to 5
years and that there is a risk of one-infour
for some level of ooding.

Flooding of the Green River Valley has the real and immediate threat to significantly impact the
operations of the Port of Seattle, including interruption of electric service to Seattle-Tacoma
International Airport (STLA). STIA receives electric
power from Puget Sound Energy (PSE)
substations located in the Green River Valley. PSE has notified the Port that if significant
ooding takes place in the valley, transmission of power to STIA may be interrupted for long
periods of time. Restoration of the power may take days, weeks or longer.

With receipt of this information, staff has begun to evaluate the options for providing 100
percent back-up power for the airport and its operations which impact the region, the United
States and the international airspace travel network.