The elected officials also received a positive update on the dam from Col. Anthony Wright, Seattle District Commander for the Army Corps. He said that new testing and analysis shows that by installing additional drains inside the embankment of the dam and the abutment of the reservoir, extending an existing drainage tunnel, and taking other measures, he can create a more durable solution for the abutment drainage issues that have plagued the structure and improve the structural integrity of the Howard Hanson Dam from the inside.
The fix will bring the dam back to its full design capacity for an extended period of time, which should provide some reassurance for residents and businesses in the cities of the Green River Valley that have dealt with the uncertainty and potential risks caused by the dam’s troubles over the past year and a half.
In essence, Col. Wright said that controlling the movement of water through drain pipes and a concrete tunnel is a solution that works as well as extending the so-called “grout curtain” as had been previously discussed, while avoiding the slow erosion that can occur to a grout curtain over time.
“After completion of these drains, I believe I can operate the dam at its full design capacity,” said Wright, who said he hopes to award contracts for the work before the end of September and have workers on the site by the first of November.
Col. Wright noted that any new repairs will only begin to protect the Valley in the rainy season a year from now. Executive Constantine said that means businesses and residents this coming winter must still remain vigilant. He noted that the region was fortunate to have a fairly dry winter last year, but that the forecast is for far wetter weather this coming winter.
The Executive said King County will continue to do its part to protect the Green River Valley – monitoring and reinforcing levees, ensuring the safety of county facilities, and working with residents and businesses to protect their homes and workplaces.
The county will also be working with regional cities and businesses to continue to raise awareness and encourage preparedness for flooding and other winter weather hazards for valley residents.
Last year’s storm preparation campaign asked Green River Valley residents: “Are you Ready?” The Executive noted this winter’s message will be: “Get Ready and Stay Ready,” and said authorities will have more information for the public as the fall approaches.