THE US ARMY CORPS OF Engineers (USACE) is studying the 42m high Tuttle Creek dam with the objective of developing a plan to reduce the risk of an earthquake breaching the earth and rock structure. A state of Kansas dam safety study has found that Tuttle Creek is at risk of damage or failure from seismic ground shaking and recommended a seismic upgrade of the dam, removal, or draining of the reservoir.
An USACE spokesman said that there was a 3% chance in the next 50 years of an earthquake registering 5.7 on the Richter scale in the Tuttle Creek area. An earthquake of that magnitude could result in significant damage to the dam. USACE found that a big earthquake could liquefy sands under the dam. The dam would crack, and water running through it would cause its failure. Tuttle Creek reservoir is about 19km west of the Humboldt fault, the most active earthquake zone in Kansas.
The Corps of Engineers has come up with a list of options for dealing with the possibility of a damaging earthquake. These being dam removal, replace or enlarge the dam, or stabilise the soil under the dam. To minimise risks it could improve seepage control, restrict lake levels, manage the downstream flood plain, improve emergency planning and improve the ability to drain the lake.