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Last Update: December 18, 2009
The Howard Hanson Dam, which is owned by the United States Army Corps of Engineers (“the Corps”), is the primary flood 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 Corps is currently assessing the damage to the right abutment and has determined that until the assessment is completed, the amount of water to be stored behind the dam will be reduced in order to protect its integrity. While the dam itself is not in immediate danger of failing, there is increased flood risk, from October through April, to downstream communities until seepage issues with the right abutment have been addressed.
Port staff has been working diligently to identify vulnerabilities and potential impacts of flooding.
Working groups have been formed at both the Seaport and the Airport to carry out needed tasks. These groups include utilities, fueling, cargo/freight transport, commuter/COOP, land use, debris management, and public safety.
The Port is coordinating all flood preparation efforts with King County Office of Emergency Management, the US Army Corps of Engineers and other agencies.
Any situation that impacts Port operations and employees will be posted on this Web site.
Staff have identified vulnerabilities and potential impacts of flooding on Airport operations. The major areas of concern are power continuity, aircraft fuel and staffing.
Fuel Supply. Olympic Pipe Line Company provides 100 percent of the fuel for aircraft at Sea-Tac. Olympic’s pump station runs through the Green River Valley flood zone, and if flooded, Olympic could be forced to discontinue service. To prepare for this, the Port and airlines worked with fuel suppliers and Olympic to increase the airfield’s on-hand fuel supply.
With this increase in supply, the airport can operate at normal capacity for about 12 days without any fuel deliveries. As a result, we do not expect there will be any interruption of commercial air traffic due to a flood in the valley. The airport uses an average of 1.3 million gallons of fuel per day.
Power Continuity. If flooding should disrupt Puget Sound Energy’s delivery of electricity, Sea-Tac Airport will have backup power. The Port leased and installed diesel electric generators that can provide up to 100 percent of the power needed to supply the Airport until power is restored.
Staffing. Up to half of the employees who work at Sea-Tac Airport live in Green River Valley communities or commute through that area. In light of this, the Port’s Aviation Division updated its continuity of operations plan to ensure that Sea-Tac will be able to operate all facilities even with staff shortages. The Port also is working with airlines, concessions and other tenants and encouraging them to update their continuity of operations planning.
The Seaport Division is working with customers, tenants and other public agencies to prepare for the possibility of flooding.
Cargo Terminals. Marine terminals will remain operational and do not expect direct impacts if flooding occurs.
Container Storage. Port and terminal operators are working to identify areas where containers may be temporarily stored if flooding delays the local delivery of cargo.
Debris Management. Port of Seattle environmental and maintenance staff members are working with the Army Corps of Engineers and the U.S. Coast Guard to monitor waterway conditions. Agencies are prepared to respond quickly to remove dangerous debris. The Port has offered berthing at alternative sites for boat owners located at the Port's Harbor Island Marina during the storm season.
Intermodal Rail Cargo. Intermodal rail cargo will continue to move in and out of the Port. The BNSF Railway does not expect impacts on its main lines. In the event of flooding, the railroad will reroute intermodal traffic to avoid flood area and BNSF track inspectors will work around the clock to ensure rail road bed safety. The Union Pacific Railroad is working on contingency plans for moving intermodal cargoes.
Power & Utilities Continuity. Seaport facilities are fed from power substations located outside of the flood impact zone. However, stormwater drainage may be a problem in some low-lying areas. Seaport Maintenance is working to identify those locations and put protective measures in place.
Roadways. Most major roadways are expected to remain open, providing access to warehouse and distribution centers south of Seattle. Local roads in the flood zone may be closed at times. Drayage routes in the harbor and freeways leading to Eastern Washington are not expected to be affected.
Potential electrical outages affecting traffic signals could add to congestion and delays.
Staffing. Some seaport employees live in or commute through the potential flood zone. Work groups have identified vulnerable functions and reviewed their continuity of operations plans with impacted workers. Alternate plans are in place to keep the business of the Port functioning through potential staffing impacts.
Warehousing and Distribution. The region's largest import distribution centers are located outside the area of potential flooding, but there are some with operations in the Green River Valley that may be affected. Many of the potentially affected facilities are developing contingency plans and taking steps to avoid damage and delays.
Shelter Option. The Port is in contract negotiations with the King County Executive's office for the potential use of the Smith Cove Cruise Terminal as a shelter for Valley evacuees if needed during a catastrophic flood event.
Sound Transit Green River Flooding Plan
Metro's Plans for Transit Service in Flooded Areas