High Yellowstone River eats up new Laurel dike

2014-06-13T00:15:00Z 2014-06-13T16:35:06Z High Yellowstone River eats up new Laurel dikeBy BRETT FRENCH french@billingsgazette.com The Billings Gazette

LAUREL — For now, the danger seems to have passed, but Kurt Markegard is still fuming.

It was after 9 p.m. on Memorial Day when the city’s public works director slipped on the newly constructed dike at Riverside Park, throwing out his back and amplifying his anger. He had been trying to rescue newly planted trees and shrubs from the torrent of the Yellowstone River, which was gobbling up the vegetation and a mesh mat meant to hold dirt in place.

“The snowmelt had come above the designed riprap we were permitted for,” he said. “About half of the trees and mats were washed away.”

It was after falling that Markegard crawled up the bank, sat down and texted the engineers who had designed the dike: “To all, I am not sure who we need to call but we are going to need more riprap. Watching a million dollars wash away this weekend is not so pleasant.

“We need the riprap to the top of the bank!

“Sorry for the late email but come morning we better have a plan started or we can just watch the park wash away.”

He then removed the tagline that says the message was sent from his smartphone and replaced it with: “Sent from the banks of the Yellowstone River.”

State and federal agencies were quick to give Laurel emergency permits to add additional riprap to the dike. By that Tuesday, Wilson Brothers Construction of Cowley, Wyo., began adding another 200 yards of rock.

Since then, the threat has subsided as the river level has receded. On Memorial Day, the Yellowstone River was running at about 39,500 cubic feet per second. Since then it’s dropped to just above 27,000 cfs.

The trees, bushes and grass had been planted on the bank only weeks earlier, the final touch to a $1.07 million project to rebuild the 700-yard-long dike next to the park, as well as add a new concrete boat ramp. But when the work was authorized, federal agencies would only allow riprap — heavy rock that armors the bank — part way up the structure.

The emergency order essentially allowed what the city and engineers had originally requested — more riprap to protect the bank.

“I’m not sure if that will remain or if we’ll do more landscaping,” said Chad Hanson of Great West Engineering, who worked on the project for Laurel. “I don’t know if the (U.S. Army Corps of Engineers) will let us leave that rock there.”

Hanson said the damage to the bank varied.

“The worst was upstream from the boat ramp about 4 to 5 feet,” he said. “Then it tapered back to the bridge.”

The dike had been seriously eroded in 2011’s high water. That July, the Yellowstone River peaked at 70,000 cfs in Billings. So even at much lower flows, the Riverside Park dike was taking a beating.

“The Yellowstone is a big river,” Hanson said. “What we didn’t expect was the wave action that came in perpendicular to the levy. The wave action was like on a beach. That was really pulling the fines out, which is why it didn’t hold up like it should.”

Laurel officials and engineers worked long and hard to try and find federal funding for the dike repair, even appealing to the state’s congressional delegation for help. The Federal Emergency Management Agency finally came through with a $1.4 million grant, but only because the dike protected utility infrastructure in the park. With the planting of vegetation this spring, the project was near completion.

Markegard said the erosion couldn’t have happened at a better time, since the city still had its contract for the work open. He is hoping that the additional unspent funds from the project will pay for adding more riprap by processing it as a change order to the original work.

Despite the quick fix and good timing, Markegard is still angry.

“This proved that it didn’t work,” he said. “We were required to put in something that was going to fail.”

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