PORT OF SEATTLE 
MEMORANDUM 
COMMISSION AGENDA  STAFF BRIEFING 

Item No.      _____7a_______ 
Date of Meeting:   October 20, 2009 
DATE:    October 7, 2009 
TO:      Tay Yoshitani, Chief Executive Officer 
FROM:    Ralph Graves, Managing Director Capital Development 
Kathleen Gleaves, Emergency Preparedness Manager, Seaport 
Ron Harmon, Emergency Preparedness Manager, Aviation 
SUBJECT:  Emergency Management Planning  Green River Flood Planning 

TODAY'S BRIEFING: 
This memo and accompanying presentation provides information on the condition of the Howard
Hansen Dam and potential effects of flooding along the Green River due to releases from the
dam this winter. The presentation also describes efforts underway by the Port to maintain critical
Airport, Seaport and Corporate operations and to cooperate in regional disaster preparedness. 
BACKGROUND 
Background  Green River and the Howard Hanson Dam 
The dam, constructed in 1962, is located upriver from Enumclaw and has served as a flood
protection dam for the Green River and numerous cities in south King County, including
Auburn, Kent, Tukwila and Renton. Once past Renton, the Green becomes the Duwamish River
and flows by several Port properties before emptying into Elliott Bay. 
The U.S. Army Corps of Engineers discovered significant damage and leakage within the
earthen portion of the dam following last winter's record rainfall. The Corps is installing a
"grout curtain" due for completion in November. The curtain is a temporary fix at best and
cannot be thoroughly tested until next summer.
To ensure the stability of the structure, the Corps will not allow the dam's reservoir to hold as
much water as it has in the past. While this cautious operation will protect against failure of the
dam, the resulting water releases may cause repeated flooding in the valley below. The Corps
estimates the likelihood of major flooding from a single event as one-in-three. 
Since the dam's construction, the valley communities have experienced rapid growth. Hundreds
of residences; manufacturing, industrial, and retail developments; and other infrastructure have

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
October 7, 2009 
Page 2 

sprung up in the valley. Transportation routes, pipelines, electrical substations, communications
nodes, and government buildings all have a home in the flood zone. Many important local,
regional and state transportation corridors cross the valley, as do the BNSF and UP railroads'
north-south mainline and the Stampede Pass line. Locally-built levees lining the river are old. 
Many were never built to withstand the flow rates likely to result from a significant storm event.
The combination of increased population density, critical infrastructure, old levees and
unchecked river flows is cause for deep concern. 
Port Impacts 
The Port faces a wide range of direct and indirect impacts from flooding that may result
from Howard Hansen dam releases this winter. 
Seattle-Tacoma International Airport may experience loss of electrical service from
valley substations for a period of days or weeks. 
Closure of the pipelines will affect supplies of jet fuel and natural gas. 
Depending on the extent of the floods, evacuation of some communities may be
necessary. An estimated 1,800 Airport employees, including workers at airlines,
concessionaires and suppliers may be displaced. One hundred and ninety employees in
the Seaport and Corporate divisions live in or transit through the impacted areas. 
Road, bridge and rail line closures may result in major congestion and stem the flow of
goods into and out of docks at the Port, as well as at terminals, air cargo facilities, and
warehouses. Flooding could affect distribution of goods to other centers outside the
region.
Debris dislodged by fast-running water could flow into the Duwamish River and may
present significant hazards to navigation in Elliott Bay. I ncreased siltation may hamper
navigation along the waterway, turning basin and at the docks. Private docks, shipping
facilities, bridges and other structures may be damaged by debris. 
The Port has received many requests from the local business community and nearby
municipalities to provide space for storage of goods and materials or evacuation needs.
(Port staff members are evaluating these requests in light of our availabilities and needs.) 
Storm water back-ups may cause flooding in some low-lying buildings in the South
Seattle area, including the Port's Maintenance Shop. 
Waterways may be affected by sewage and storm-water overflows. 
The Port's police and fire departments anticipate increased demand for services from Port
facilities, as well as calls for mutual aid from valley cities.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
October 7, 2009 
Page 3 

NEXT STEPS 
Flooding of the Green River will likely not be a one-time event. The Corps estimates permanent
repairs could take from three to five years. Local jurisdictions, aided by federal grants, are
rushing to complete levee improvements and mitigation projects and plan for the evacuation of
up to 35,000 residents, and their pets and livestock. Levees are being reinforced, and efforts are
underway to install protection for, or to relocate, critical infrastructure and services. 
Port staff members have been developing response plans to the flood potential. This includes
updating operational contingency plans at Sea-Tac Airport, the Seaport and other Port facilities;
assisting tenants and customers in maintaining their business operations; communications plans
for employees, tenants, vendors and the public; and coordinating with local, state and federal
governments. 
Port staff members are also coordinating with their counterparts in valley cities, county and state
governments to develop contingency plans, and are beginning discussions with freight, railroad
and distribution companies about potential impacts to their operations. 
In the last two months, Port staff members have participated in regular meetings coordinated by
King County, met with the Red Cross, attended the utilities briefing, the truckers' association
briefing and a symposium for business owners organized by the combined chambers of
commerce in the valley cities.
Specific topics include: 
Identifying impacts to freight movement at both the Airport and Seaport 
Engaging in outreach and communications to tenants, shippers, and customers
Refining land use policies  identifying available lands, determining what needs the Port
may have internally and what properties or facilities can be made available to outside
entities 
Identifying and mitigating potential damage to Port properties and facilities 
Identifying and mitigating potential operational impacts at all facilities 
Preparing for loss of electricity, jet fuel, gas and other utilities 
Preparing for clean-up and recovery 
Currently the City of Renton and King County have declared a State of Emergency. The cities of
Kent, Tukwila and Auburn will soon follow suit. The State recently increased its response level
to the Howard Hanson Dam to a Level 2, ** and FEMA is already working with local

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
October 7, 2009 
Page 4 

jurisdictions. Emergency Declarations by state and local governments open the way for
increased federal assistance now and in the future. 



**Note on Terminology: 
Level 1: Normal Operations. 
Level 2: Staff members are monitoring the situation, providing coordination specifically
for the dam issue. Staff members dedicated to it full time on a continuing basis Mon-Fri
8-5. 
Level 3: 24/7 Operations at the State EOC. 
Level 4: Catastrophic; full mobilization of State resources.