Spillway Repair - 2007
Houston, we have a problem!
The Corunna dam was not in a great state of repair when the city purchased the adjacent Mill Site in the 70's. Over the past 35+ years, the dam has experienced additional deterioration. No maintenance or repair activity was conducted over this time period.
The main structure of the dam is is a timber crib. Over the past several years, the Corunna Dam Review Committee reviewed options for repair, replacement or removal of the dam. No "cheap" option exists, with estimates ranging from $600,000 to $1,200,000.
During the course of our evaluation, significant problems developed. Shown above are photos of the west spillway. Water by-passing the structure began shifting the west wall. This problem created worries about the possible failure of the wall and the impact on neighboring property owners, Heritage Park, and North Shiawassee Street.
Estimates to re-construct the spillway came in at over $400,000. It was determined that this would be far more expensive a project than we could afford, given the problems with the main dam structure that would not be addressed.
The City of Corunna, working in conjunction with Spicer Engineering and local contractor SL&H, devised a repair technique consisting of installation of steel braces and injection of flowable fill.
This work was completed in the month of February, 2007, at a construction cost of less than $17,000. Although not a "long term" fix, this project will allow for the continued discussion of a permanent solution, without the fear of a failure of the west wall.
Special thanks to SL&H Contractors of Corunna for their help!