New London dam to be replaced this summer
NEW LONDON -- Construction is set to begin this week on a project to replace New London's Mill Pond dam.
The $2.6 million project will be completed before freeze-up late this late fall if weather cooperates.
The current dam, with a narrow opening on the intake side and stone arch on the downstream side, will be replaced with a large labyrinth weir that will look dramatically different than what's there now.
New London City Clerk Trudie Guptill, whose office sits near the edge of the dam, kind of grimaces and shrugs her shoulders when asked to describe how the new structure will look.
Even those intimately involved with designing and overseeing the project don't have ready words.
"It's hard to explain," said Glen Bengtson, project manager with the Department of Natural Resources.
"It's going to look very different than it does now," said Jason Boyle, DNR state dam safety engineer.
After a two-year long study design process to analyze and engineer the project, work is now ready to begin.
The roadway on top of the dam is currently 12 to 13 feet long. When the new dam is done the expanse vehicles will drive on will be 50 feet.
The new dam, including what's underwater and what's exposed, will apparently involve a lot of concrete.
"Some people don't think a big slab of concrete looks pretty," said Boyle.
"We think it's going to look beautiful," said Bengtson. "It's going to look different."
When there's a full flow of water the dam will have a "pretty interesting" look, he said, adding that most of the time there's just a "trickle of water" going over the dam.
The use of architectural concrete will give the project the look of real stone, which should have a positive effect on the appearance.
But safety, not beauty, is the reason the dam is being replaced.
Originally built in 1865, with significant modifications made in the 1930s or 40s and repairs made in the 1970s and 1990s, the dam has been classified as substandard and is on the DNR's list of "high hazard" dams.
There's a fear that if the dam fails water from New London's picturesque Mill Pond, which holds back water from the Middle Fork of the Crow River, would flood the town.
The current dam also has uncontrolled seepage downstream the DNR wants to control.
A safety railing along the pedestrian walkway on the dam will be more attractive than the chain link fence that had been in place, said Boyle, reiterating that the goal of the project is "safety - first and foremost."
Funding for the project is coming from state bonds that was included in bonding bills from 2005, 2006 and 2008, said Bengtson.
Bids for the project, which came in slightly below the estimate, were awarded last month. There were 10 bidders for the project, with Lunda Construction of Rosemount, providing the low bid.
Replacing a dam will not an easy process.
A temporary structure, known as a coffer dam, will be built to hold back water in the Mill Pond while the old dam is removed and the new one constructed. A de-watering system will continue to channel water downstream.
Use of the Mill Pond will not be affected during construction. People will still be able to swim, canoe and fish there, said Bengtson