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U.S. Army Corps of Engineers
St. Paul District
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St. Paul, MN 55101
Phone: (651) 290-5807
Fax: (651) 290-5752
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District dewaters lock and dam for maintenance

Published Jan. 25, 2012
The lack of ice and the presence of standing water at the bottom of Lock and Dam 7’s dewatered chamber near La Crosse, Wis., marks a drastic change from last year’s routine winter maintenance, when often times work was done during below zero temperatures. This year, with warmer than normal weather, everything is easier than normal, said Scott Uhl, the crew’s foreman. The improved weather conditions have helped the maintenance and repair crew from Fountain City, Wis., to get slightly ahead of schedule. 

The district is in charge of maintaining 13 lock and dams along the Upper Mississippi River from Minneapolis to Guttenberg, Iowa. These lock and dams go through a 15 to 20 year cycle of routine winter maintenance. Lock and Dam 7 received this maintenance three years ahead of schedule due to damage on the gates that forced the dam to not operate at its normal pace during the most recent navigation season. 

The lock was dewatered at a rate of 6 inches per hour on Dec. 5, 2011, marking the end to the navigation season and the beginning of work for the 36-person repair crew. Maintenance this year includes repairing the miter gates, bubbler systems and deteriorated concrete on the lock walls, as well as a facelift with approximately two full barges of sand and zebra mussels being taken out before repairs could start. Even with the lock and dam getting maintenance three years ahead of schedule, “No repairs were out of the ordinary this year after the chamber was dewatered,” said Uhl. 

The affect of the warm weather is not the only difference from last year. The district became the owner of a new crane mounted on a barge this year. This crane has a 200-ton capacity and is used for placing stop logs outside the gates to prevent water from coming back into the dewatered chamber. These stop logs weigh about 76,000 pounds each and the pick-up beam weighs about 64,000 pounds, said Bryan Peterson, chief of the maintenance repair section. In previous years, Rock Island District’s crane and crew were needed for this work. For Uhl, having their own crane to complete tasks allows the Fountain City crew to stay on the same page, which is another factor that has heped the crew get ahead of schedule.

Peterson said routine winter maintenance also provides an opportunity for district employees to complete other repair work that would normally be completed on land in a dry dock. This repair work includes the 90 barges that are owned and operated by St. Paul District. These barges used on projects such as mechanical dredging often need repairs after being heavily used during the navigation season, he added. Some of these barges are brought into the chamber loaded with equipment prior to dewatering the lock. They are then repaired during the winter for the upcoming navigation season. Even if there are only two barges being repaired, Peterson said it still saves money. “It is more efficient and reduces repair costs for the district every winter,” he said.

Lock and Dam 8 near Genoa, Wis., is scheduled for maintenance next year. But for now, Uhl said, the crew is happy to be working near their home. “The camaraderie that is made while spending every night in a hotel is amazing, but it is nice going home every night to your own bed.”