The U.S. Army Corps of Engineers, Detroit District, operates and maintains nine federal dams on the lower Fox River in Wisconsin. Of these nine dams, four are rated as DSAC II (Unsafe or Potentially Unsafe), and five are rated DSAC IV (Marginally Safe).
The four dams that received the DSAC II rating are the Upper Appleton, Cedars, Little Chute, and Rapide Croche dams. These four dams received DSAC II ratings due to concerns with potential gate failure. Cracks in the vicinity of gate anchorages have been monitored by Corps staff since the 1970s and are not showing signs of rapid progression.
The remaining five dams, Little Kaukauna, Menasha, Lower Appleton, DePere, and Kaukauna dams received DSAC IV ratings.
The U.S. Army Corps of Engineers, Detroit District, prepared an Interim Risk Reduction Measures Plan (IRRMP) for all DSAC II dams to reduce risk to acceptable levels until permanent repairs are implemented. The plan defines actions such as sealing concrete cracks, increasing dam monitoring, and updating emergency action plans. The Emergency Action Plan is updated annually.
The Detroit District awarded a contract to Lunda Construction for permanent gate repairs at Cedars, Little Chute, Rapide Croche, and De Pere dams in July 2009. The contract was modified to include gate replacement at the four dams due to advanced corrosion of the steel. Gate repairs have been completed and significantly reduce the risk of dam failure at these locations. The DSAC ratings for Cedars, Rapide Croche, and DePere dams have been requested to be reclassified and area awaiting approval from Headquarters. In June 2012, DePere dam was approved to be improved to DSAC IV status.
The DSAC rating for Little Chute dam will remain DSAC II at this time. Seepage and sinkholes have been discovered at the dam and monitored ever since. A sheet steel cutoff wall was installed in November 2011 and monitoring wells are used to reduce the risk of dam failure until a permanent seepage barrier is constructed. Little Chute dam will maintain its DSAC II rating until the permanent solution is implemented.
Several deficiencies were noted at Kaukauna and Little Kaukauna dams including pier concrete deterioration and gate steel issues. These are not new findings, but their conditions have warranted reclassification requests to the DSAC ratings to reflect a higher risk situation. Detroit District is budgeting for gate and pier work, similar to those done on DePere, Rapide Croche, Cedars, and Little Chute dams in 2009.
The U.S. Army Corps of Engineers is committed to transparent and honest communication with the media and public and will continue to update affected communities as plans develop.
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