The U.S. Army Corps of Engineers, St. Paul District, recently awarded a $133,611 contract to Tunheim Construction LLC, out of Moorhead, Minnesota, to construct an upstream cofferdam for the Chippewa Diversion, near Watson, Minnesota.
“This project is a short-term construction project that will allow the immediate area upstream and downstream of the diversion structure to be dewatered,” said Will Wolkerstorfer, project manager. “Once the area is dewatered, the Corps’ maintenance and repair crew will make routine repairs to the structure’s Tainter gate.”
The contractor will construct the upstream cofferdam with soil and reinforce it with plastic. A Corps team will install a cofferdam downstream of the structure. Once both cofferdams are in place, the immediate area around the Tainter gate will be dewatered to allow Corps staff to repair the gate. The cofferdams will be removed and the area will be restored to its pre-construction condition once the repairs are complete.
There will be minimal impacts to the Chippewa River flows and the Lac Qui Parle reservoir and Watson Sag will be maintained at the conservation pool levels during the maintenance. Work on the project is anticipated to begin in early September. The cofferdams are expected to be in place by October 2, and will be in place for two to three weeks or until the maintenance is complete.