Construction crews working on the CapX2020 Mississippi River crossing have discovered a new method of carpooling. During the past few months they have abandoned their trucks for a tug boat and barge, and they are commuting on the river in all kinds of weather. Crews are constructing a triple circuit transmission line, which includes the CapX2020 Hampton-Rochester-La Crosse 345 kV circuit. Work on the river crossing is occurring between the Minnesota and Wisconsin border near Wabasha, Minnesota and Alma, Wisconsin. The construction process includes building two locations, on an island and a peninsula, that are only accessible by barge and boat. This involves using a barge to transport hundreds of concrete trucks, cranes and structure pieces weighing over 100,000 pounds.
Five structure sets stretching just over a mile and 15 pile cap style foundations are part of the river crossing. The massive foundations, designed by a bridge engineering firm to withstand erosion from spring floods, required 4,500 cubic yards of concrete. That’s enough concrete to build a six foot wide sidewalk that is 11 miles long.
The new line is being built adjacent to an existing Dairyland Power Cooperative 161/69 kV line constructed in 1955. The existing structures and line are being removed and replaced with the new line. The final project plan comes after years of collaboration with the U.S. Fish and Wildlife Service (FWS) which manages the property on the Minnesota side of the crossing. Rebuilding the existing line allows the transmission conductors to be on a horizontal plane, which is an accepted practice reducing the likelihood of bird strikes.
The project required significant coordination among government agencies, engineering firms and contractors. Contingency plans were set in place to assure the work is completed prior to eagle nesting season, another requirement of the FWS. “For all our planning, one thing we could not control is the weather,” said Grant Stevenson, Xcel Energy project manager for the CapX2020 Hampton-Rochester-La Crosse project. “We planned the start of construction for August 1, typically a low water period on the river. But this late summer brought unusually high water levels on the Mississippi that delayed our start of construction. After the waters receded, the river was closed to barge traffic because sand washed into the shipping channel. Thanks to great cooperation with our contractors, we managed to work through these issues and expect construction to be complete in January 2015.”
Several local contractors are working on this challenging project:
• Trinity Meyer Company: Hager City, Wisconsin for structures
• J.F. Brennan Company: La Crosse, Wisconsin for foundation construction and crane and barge operations
• Wabasha Ready-Mix: Wabasha, Minnesota for concrete
• Sowles Company: Shakopee, Minnesota for reinforcing steel
• Dahn Construction: Rosemount, Minnesota for matting and restoration services as needed
• Xcel Energy crews are installing poles and conductor.