In response to the increased risk of flooding in the Green River Valley due to limited storage capacity at the U.S. Army Corps of Engineers Howard Hanson Dam, the King County Flood Control District Board of Supervisors revised the 2009 capital budget and six-year capital improvement plan to provide additional money for emergency flood-protection efforts in the Green River Valley.
“We are facing an unprecedented and urgent situation in the Green River Valley, and we are taking the steps to prepare,” said Flood District Chair Julia Patterson, whose King County Council District represents valley communities. “These efforts will enhance flood protection for people, property and commerce in the valley.”
The Green River Valley is at risk of serious flooding as a result of reduced storage capacity due to concerns about the compromised right abutment of the dam. During heavy rain events, the Corps may be forced to release substantially more water into the Green River, which would result in higher peak flows of longer duration that could exceed the capacity of the levee system.
“The stakes are too high not to prepare now,” said Flood District Supervisor Pete von Reichbauer, whose Council district represents Auburn and parts of Kent. “Serious flooding would be devastating to our residents and businesses, their property, and our regional economy.”
The Flood District’s action re-allocates approximately $8.4 million for temporary infrastructure to increase the height of the Green River levees to accommodate higher flows. The funding will also make certain that measures have been taken to ensure maximum operational capacity of the Black River Pump Station. The pump station provides critical pumping capacity to drain the lower Green River Valley during a flood.
Green River flooding would affect the entire region as the area is home to tens of thousands of residents, major employers and the region’s largest warehouse and distribution operations. The BNSF Railway’s mainline also runs through the valley, connecting commerce in the Northwest to the rest of the country. A significant amount in economic output would be lost for each day that a flood event shut down those industrial areas.
“The Flood District was created to provide much-needed funding to accelerate repairs on our flood-protection infrastructure and to provide additional flood protection throughout King County for situations just like we have in the Green River Valley,” said Flood District Executive Committee Chair Reagan Dunn. “With this action, we are truly addressing an issue that will have local and regional impacts.”
King County agencies are actively pursuing reimbursement from the federal government for costs associated with the Howard Hanson Dam situation.
Highlights about the uses for funding include:
• Temporary Levee Infrastructure: Alternatives for temporarily increasing levee protection under consideration include supersized sandbags called “super sacks” that are moved utilizing a forklift, and “container units” which are sandbags that are structurally reinforced using collapsible wire mesh.
• Black River Pump Station: Plans to ensure the pump station stays fully operational during a flood event include constructing a temporary embankment around the pump house to keep out floodwaters, possibly utilizing additional pumps to augment the existing capacity at the pump station, and purchasing or renting a backup generator to ensure full electrical power to the pump station’s equipment.
Information about the King County Flood Control District can be found at www.kingcountyfloodcontrol.org.
