MANKATO — Blue Earth County will seek to remove the Rapidan Dam while replacing the County Road 9 bridge, after commissioners Tuesday narrowed down options for the flood-damaged area.
Heavy rainfall contributed to the Blue Earth River bypassing the dam in June, eroding the west embankment and compromising the bridge’s structural integrity.
The development drew national and state attention as erosion claimed a home along the bank. It next threatened the homeowners’ iconic Dam Store, prompting the county to buy it and tear it down.
Since then the county has been exploring several options for the bridge and dam’s future, including replacing or removing both. Commissioners cited cost and safety considerations as factoring into Tuesday’s decision, which directs staff on how to proceed with state or federal partner agencies.
Commissioners first unanimously approved replacing the bridge rather than removing it with no replacement.
The bridge, constructed in 1985, hasn’t been open since the June flooding. Bob Meyer, county administrator, told commissioners that engineers deem the bridge no longer safe for travel.
While a bridge at that location doesn’t have high-traffic volumes, said Commissioner Kip Bruender, the farm-to-market trips are an important consideration.
“My understanding is it’s a road that gets used a lot for crops and getting in and out of the fields and getting grain to the market, so I think that’s probably the bigger weigh-in here,” he said.
Without the bridge, said Commissioner Vance Stuehrenberg, farmers on one side of the river may have to travel 45 minutes or longer to get to fields on the other side.
“If they’re driving a combine, it’s a lot longer,” he said.
He added that it’s a big nature area as well and adding a bicycle trail through any new bridge would be a good idea.
The county can access about $19.5 million in County State Aid Disaster Account funds for bridge removal and replacement, according to County Board documents. The total could then be reallocated back into the fund when federal Federal Highway Administration and Local Transportation Disaster Support Account money kicks in afterward.
Preliminary costs for removing the dam range from $59 million to $75 million, according to an updated estimate provided by Barr Engineering on Aug. 15. The estimate was based on a 2021 feasibility study by the firm, with more evaluation needed to zero in on an updated cost.
The county would seek federal funding to cover much of the removal cost. Staff was directed to work with the Federal Emergency Management Agency, or FEMA, on options.
David Hruska, whose family ran the Dam Store, said the dam removal decision didn’t come as a surprise. The family, which is readying a temporary location in the old Wagon Wheel location on Front Street in Mankato, still intends to rebuild out in Rapidan but will need to wait on the county’s plans for the bridge and surrounding area.
“We’ve just got to wait until we get everything back to somewhat normal,” he said. “We’re just lucky to have a temporary spot.”
Other choices for the dam’s future included repairing it and the area around it to pre-disaster levels, replacing it, or keeping it as is while shoring up the current river channel.
In response to the repair and restore option, Commissioner Kevin Paap said he didn’t see it as the best path forward. It would involve hauling tons upon tons of material in to “fill the rest of the hole,” he said.
His fellow commissioners concurred, then ruled out retaining the dam as is. Ryan Thilges, county engineer, had just shared how difficult it would be to keep people off the dam if they kept it in place.
It could be just a matter of time before someone got injured or worse, creating a liability concern, he said.
He also expressed concerns about the dam structure creating an awkward river flow requiring robust armoring to slow or prevent further deterioration of the bank. Even then he said he still didn’t have much confidence in stabilization efforts being effective.
“I would anticipate that that’s going to be kind of a continual problem child on that west embankment trying to protect it and a little bit of a money pit in the long term,” he said.
Commissioners unanimously approved the removal option, which is tied to a river restoration component. County staff will work with the U.S. Army Corps of Engineers to restore the river channel post-dam removal.
The county and other stakeholders should form a group to discuss the future of the river, Stuehrenberg said. They’ll be tasked with figuring out how to get recreation opportunities, including kayaking and bicycling, and other usage around the site back to what they were before.
Follow Brian Arola @BrianArola
