In July of this year, Kaukauna Utilities maintenance crews noticed a sinkhole believed to be caused by an eddy effect (circular current of water) in the corner of the power canal near the trash rack structure by the USACE Dam. For safety, the Badger Hydro plant was shut down immediately to further investigate the issue. Divers from Underwater Construction were brought in to evaluate the problem and reasoning for the sinkhole on the outside of the power canal wall. It is believed the 1” trash racks and velocities at the corner where the canal wall and trash rack meet caused an “eddy effect” in the corner, and over the years has been slowly washing away the gravel fill under the structures. The foundation of the canal (under the retaining wall and trash rack structure) was slowly starting to wash away and create a sinkhole. After Kaukauna Utilities’ staff, along with the divers, were able to pinpoint the problem, the Federal Energy Regulatory Commission (FERC) and DNR were notified immediately.
A contractor was brought in to assist Kaukauna Utilities with a repair plan. A cofferdam (a structure that retains water to allow for repair) was constructed around the scour area to dewater and determine the extent of the issue. Further, the scour areas were cleaned, and concrete grout will be used to fill the area to prevent this from happening again. The area is still currently under repair; however, Kaukauna Utilities customers should know that every precaution is being taken to fix this issue safely, effectively, and in a timely manner. With questions, please call Kaukauna Utilities – 920-766-5721.