Friday, August 3, 2007

Dam Operations to Help with Recovery and Reconstruction Efforts at Collapsed I-35W Bridge Site

It was reported that the recovery (sadly) efforts were hindered by the rapid and turbid river current at the collapsed I-35W Bridge site. I believe the rapid current was due to water falls upstream, and the turbid water was due to its high soil and organic contents that was made worse by debris from the collapsed bridge.

The Google map/image shows the I-35W Bridge, and the Upper and Lower St. Anthony Falls. You can see the rapid currents at downstream sides of both Falls. The I-35W Bridge is in rapid tail water of the Lower St. Anthony Falls.

To help the recovery efforts, water level was lowered in the Mississippi River at the bridge site, by opening up more the downstream Ford Dam (a part of the Lock and Dam No. 1 System). But this made the current at the bridge site even faster, thus tougher to anchor and stirring up even more debris. It was a tricky engineering that helped with the recovery efforts.

Maybe they could additionally change operations at the lock and dam systems associated with the St. Anthony Falls upstream, and lower the gates at the Coon Rapids Dam further upstream to hold more water.

Well-coordinated opeartions of downstream and upstream dams would also likely help a rapid and smooth reconstruction of the bridge.

What a horrible event! May the recovery and re-construction efforts go well!

PS: I lived in a rooming house close to the bridge while a graduate student at the University of Minnesota. I still remember the sound of I-35W traffic as well as the view of St. Anthony Falls!

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