Minnesota’s Rapidan Dam is in ‘imminent state of failure’, officials say – InForum

Minnesota’s Rapidan Dam is in ‘imminent state of failure’, officials say – InForum

Minnesota’s Rapidan Dam is in ‘imminent state of failure’, officials say – InForum

RAPIDAN — Authorities say the Rapidan Dam, under intense pressure from days of torrential rains and collected debris, is in an “imminent state of failure.”

“There was some debris that came up from the dam and that caused the water to find a new path around it and cut west to where The Dam Store is and the residence that’s down there,” said Deputy Chief Paul Barta. of the Blue Earth County Sheriff’s Department at the scene on Monday morning, June 24th. “And it basically eroded the west side of the dam and created a new path through there. He took a substation for the power plant in the river.”

Barta said authorities have informed residents downstream of the dam about the potential danger.

“We think it’s an imminent threat, just because none of us are hydrologists and don’t really know; there are a lot of variables with that,” Barta said. “It’s pretty significant.”

A press release from Blue Earth County said: “The Offices of Public Works, Emergency Management and Sheriff are implementing the steps outlined in the Rapidan Dam Emergency Action Plan for imminent dam failure, including notification of potentially affected residents, affected regulatory agencies and other local agencies”.

Officials in Mankato, North Mankato and Blue Earth and Nicollet counties say they are closely monitoring the dam situation, but say they are confident the flood control system will protect the two towns even if the dam fails.

Just after 12:30 p.m., North Mankato city officials sent out an announcement trying to reassure residents that even a complete dam failure would not endanger the city.

“Our earth levee at Lookout Dr. and Lee Blvd. is built to a height of 34.6 ft. and is constructed out of an abundance of caution,” the announcement said, referring to an emergency levee built from this morning to fill a gap in the permanent flood control system. “If the Rapidan Dam fails, on-site engineers predict a rise of 6 inches to 2 ft, depending on the downstream location. The City of North Mankato has a staff member on site at the Rapidan Dam providing updates.”

The river at Mankato was at about 28 feet Monday, and the levee system is built to protect up to 39.5 feet. Officials said if the entire Rapidan dam went out, it would add a 2-foot rise in river levels, which would still leave more than 9 feet of capacity for the floodwall system.

People may also notice that Xcel Energy is doing a lot of activity around Sibley Park. As a precaution, Xcel is bringing in 170 employees and 400 pieces of equipment to protect the nearby substation. People can also see a lot of Xcel equipment at MSU. They use the campus as a meeting area. We will continue to provide updates as events develop.

At The Dam Store on Monday morning, Louise Henderson, family friend of David Hruska and store owner Jenny Barnes, was among those helping to remove what they could from the house next to the store.

“The house is in serious danger and we’re trying to get everything out,” Henderson said.

The river bank near the shop and house was being quickly eaten away by the strong currents of water.

Henderson, who lives on top of the hill near the dam, said he heard transformers at an electrical substation at the dam begin to explode loudly and then heard steel twisting as the substation was thrown into the river. That caused power outages in Good Thunder and other areas.

She said the support has been strong. “The number of people who helped was phenomenal.”

Henderson said when she arrived at the freeway bridge behind the dam early this morning and saw the scene, she was hit hard.

Map Rapidan MFP.jpg

Christina Sankey / Mankato Free Press

“I watched my childhood coming down the river. This is where I grew up. My family has been here for generations.”

Her great grandfather started the dam store in 1910 to feed all the men building the dam.

Amy Strand also grew up near the dam and was one of the hundreds of people who parked on top of the hill east of the dam and walked down to watch the devastation. The county had blocked off the freeway bridge behind the dam at both ends.

“I’m worried if the whole dam breaks and what would happen to the bridges and the people downstream,” she said.

She too carried fond childhood memories of the dam and The Dam Store.

“We used to ride our bikes here when we were kids. There wasn’t much to do here, so that was it.”

Officials were checking bridges downstream of the dam, including the County Road 90 bridge, to watch for trees and power poles that could get stuck in the bridges.

If the situation were to worsen, Barta said they would increase efforts to notify residents and businesses downstream. However, they cannot force anyone to evacuate.

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North Mankato city workers began work Monday morning, June 24, 2024, on building an earth levee to reinforce flood walls in case the Rapidan Dam south of the city breaks.

Mike Lagerquist / Mankato Free Press

“In the state of Minnesota, law enforcement cannot enforce an evacuation,” he said. “We can’t tell people they have to leave their private property. People have an individual right to make assessments about whether they want to stay or go. So we make a recommendation, but we can’t force them.”

The debris that collected near the dam worsened the already dangerous situation, causing the river to recede and reroute itself around the dam, dangerously close to the beloved Dam Store.

The gridlock caused power outages early Monday. Xcel Energy’s outage map showed 579 customers affected in the Mankato, Lake Crystal and Good Thunder service areas as of 10:30 a.m.

The debris remains packed tightly against the dam, but Barta said it would be too dangerous to try to remove it. He recalled the 2014 incident in which Michael Struck was trying to remove floodwater debris from Seven Mile Creek. The strong current overturned the backhoe. Struck was in service and Struck was pulled under and through a canal.

“Trying to wipe some of this stuff off can be just as problematic as trying to let some of it wash away,” he said. “We were lucky that nothing broke apart and flowed down the river. Trees and things like that haven’t created a problem yet.”

The City of North Mankato has declared a flood emergency, closing the Lookout/Lee Boulevard intersection beginning at 9:30 a.m. to allow crews to construct the temporary earthen levee in this area.

The dam was the center of attention

In recent years, the dam has been at the center of intense scrutiny and emotion over its future.

Blue Earth County, which owns the dam, considered whether to repair the dam, built in 1910, or remove it.

Many wanted to save the dam because of its historical and social value. But others said it was better to remove dams to return the rivers to their natural state.

And some argued that removing the dam could allow the creation of an artificial whitewater rapid that would attract tourists.

Both options came at a high price. In 2022, the repair cost was set at $15 million, with a staggering $82 million price tag to remove it. A large part of the cost of the dam release was the removal and disposal of the huge amount of sediment that had filled up behind the dam for over a century.

This sediment is near the top of the back of the dam. But that sediment begins to flow through the newly carved channel next to the dam and down into the Minnesota and then the Mississippi rivers.

Its environmental and other effects are still unknown.


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