Coon Rapids Dam project moves ahead

A bid for the manufacture of the new steel gates for the Coon Rapids Dam is expected to be approved by the Minnesota Department of Natural Resources (DNR) in the next week.

The rubber gates at the Coon Rapids Dam will be replaced with steel gates. File photo

The rubber gates at the Coon Rapids Dam will be replaced with steel gates. File photo

According to Jason Boyle, DNR state dam safety engineer, the low bid of $3.5 million was within the latest estimates for the $16 million project to replace the existing rubber gates structure at the dam.

The 2011 Minnesota Legislature approved $16 million as part of a state bonding bill signed by Gov. Mark Dayton to reconstruct the Coon Rapids Dam to make it a more effective Asian carp barrier.

Once the contract is awarded, the company that will manufacture the new steel gates has to present shop drawings for approval to Stanley Consultants, Minneapolis, the firm selected by the DNR at a cost of $900,000 to handle design and engineering work for the project, Boyle said.

Once the shop drawings are approved, manufacture of the steel gates will begin, he said.

“Delivery is scheduled in the spring of 2013,” Boyle said.

Stanley Consultants is also continuing design and engineering work on the overall project, he said.

This is scheduled for completion by the end of the year, at which time the DNR will go out for bids for a general contractor so that construction can begin in the spring of 2013, Boyle said.

The project at the dam has been split in two phases, with work on the Anoka County side of the Mississippi River taking place in 2013 and on the Hennepin County side in 2014, according to Boyle.

On the Anoka County side of the dam next year, a cofferdam will be built – construction of a temporary enclosure at the dam to allow water to be pumped out so that work can take place in a dry area – the existing rubber gates will be removed and the new steel gates will be installed, Boyle said.

The same process will be repeated on the Hennepin County side in 2014, he said.

Work will also take place downstream of the dam next year to fix scour damage to the apron of the dam, which was discovered by an underwater sonar scan in 2009 and prompted the decision to look at all issues related to the dam and its future.

The entire project is anticipated to be completed in the fall of 2014.

According to a press release from the Three Rivers Park District, which owns and operates the dam, the recreational pool above the dam will be maintained at the normal summer level indefinitely and will no longer be lowered in the fall and raised in the spring.

“At the direction of the DNR, the pool will be at or near the normal summer pool level year-round in order to maximize the dam’s effectiveness as an invasive species barrier, in particular, a barrier to the Asian carp,” the press releases states.

It was a reconstruction plan for the dam Stanley Consultants, working for the park district, presented in early 2011 to the Coon Rapids Dam Regional Commission, which was established by the 2010 Minnesota Legislature to consider the future of the dam, that was the basis for the $16 million state bonding bill allocation in 2011.

Stanley Consultants had been hired by the park district to evaluate the effectiveness of the dam to keep invasive fish species, like the Asian carp, from moving upstream.

The proposal Stanley presented last year would replace the rubber gates presently in place at the dam with steel gates that pass water over the top of dam.

That would be an ideal fish barrier and would make the dam 99 percent effective as a barrier to invasive fish species, Marty Weber, an engineer with Stanley Consultants told the commission last year.

A joint powers agreement signed by the Three Rivers Park District and the DNR earlier this year paved the way for the dam reconstruction project.

Under the agreement, the DNR will rehabilitate and manage the dam, while the park district remains responsible for routine maintenance and day-to-day operations of the dam as well as ownership.

In addition, the Anoka Conservation District (ACD) has received a $10,000 grant from the DNR to inventory the condition of the shoreline along the Mississippi River from the dam upstream to the Highway 169 bridge in Anoka and Champlin.

The ACD project is scheduled to be completed by the end of this year and include a detailed inventory of the condition of the shoreline along this stretch of the river and provide a database for possible shoreline bank stabilization grant applications.

The Coon Rapids Dam was built in 1913 by Northern States Power (NSP) Co. to generate hydroelectric power.

When power generation stopped in the 1960s, NSP donated the dam and surrounding land on both sides of the river to the park district.

Anoka County now owns all the park property on the Anoka County side of the dam.

Peter Bodley is at peter.bodley@ecm-inc.com

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