Engineers running tests on Howard Hanson Dam
Engineers, geologists and various scientists are at the Howard Hanson Dam right now running a battery of tests to see how effective recent drainage improvements will be once next year’s flooding season arrives.
Among other tests, the team will gather information about seepage rates through the dam’s right abutment, which will help determine how much more work is needed to reduce flood risk in Auburn, Kent, Renton and Tukwila.
US Army Corps of Engineers spokesperson Patricia Graesser said the tests will hopefully prove that recent upgrades and improvements to the drainage system are as effective as they’re supposed to be, but the engineers won’t know for sure national experts review the collected data.
If all goes as planned, the tests will show if the dam can return to its authorized flood-risk reduction operation, which Graesser said will put the odds of valley flooding at 1 in 140. For comparison, the dam was operating at 50 percent storage capacity last December, which meant the odds of flooding were 1 in 60.
The tests will take a few weeks to complete.
