May 22, 2012

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Large “void” found during inspection of key Missouri River dam

May 10, 2012 By

Gavins Point Dam near Yankton, SD

The Missouri River fell nearly eight feet on Wednesday as the U.S. Army Corps of Engineers shut off the flow from Gavins Point Dam near Yankton to inspect the concrete slabs below the spillway gates.

Three teams used sophisticated radar to survey for damage. Dave Becker, the Corps’ operations manager for the dam, says they’ve seen warning signs develop since last year’s historic flooding across Iowa and Nebraska.

“We have a foot and a half of concrete on top and that is on top of a four-foot gravel layer,” Becker says. “Ever since January, we’ve had concerns about that gravel layer. We had a couple of gates open, gates 2 and 3 at this south end, and we saw water coming out of the drain at the north end and we said, ‘That’s not right.’”

Becker says the record flows that brought the prolonged, record flooding last summer caused damage under the concrete.

He says, “What we found was that some of the drain grates had been washed off during the flood and some of that water was going straight down the drain holes and into the gravel layer and eroding some of that gravel.”

He says the concrete is all fine but there’s at least one large “void” in the gravel. Becker says crews used the low water level on Wednesday to get a closer peek at the problem areas.

“The ground-penetrating radar takes a look at the concrete and the gravel area underneath to see what condition it’s in and to see if there are any voids,” he says. “They also drilled holes in the concrete so they can visually just take a look down there and see what they got, they can stick a piece of rebar down there, feel around, see what they got.”

Becker says there are no structural issues with the spillway and they are not worried about any leaking.

He says they hope to get the spillway repaired before next spring. Flows on the river were restored about midnight and the river’s level today is back to normal.

By Jerry Oster, WNAX, Yankton

Filed Under: Accidents & Disasters, Environment & Conservation, Featured Stories, Military, News, Weather

Gavins Point spigots to be shut off for radar imaging of flood damage

May 8, 2012 By

Gavins Point Dam

Damage assessments using a special type of radar will be conducted this week on a key Missouri River dam following last year’s record flooding. The U-S Army Corps of Engineers is focusing on the spillway slabs at Gavins Point Dam.

John Remus, chief of the Omaha District Hydrologic Engineering Branch, says the teams will take a close look at material under the concrete slabs.

“Some of the frost blanket, which is a granular material, has been removed from under the slabs,” Remus says. “We don’t know how much has been removed and the extent of that depth-wise, so we’ll bring in some ground-penetrating radar. There’s going to be three crews, working their way across the slab to quantify the extent of this damage.”

The investigation will start Wednesday at 8 AM and releases from the dam will need to be reduced to nothing for about eight hours to drain the uppermost portion of the spillway. Remus says stopping the water flow will give them a good look at the entire slab below the spillway gates.

“We do believe so, based on what we saw this last Tuesday when we drew it down to 12,000 CFS (cubic feet per second),” he says. “The drains have responded quite quickly. We also saw that during the flood when we drew down the discharges from the spillway. We’re confident we can get the information we need to get in the eight hours that we have scheduled for this.”

Stage reductions at Yankton, Sioux City and Omaha are expected to last for about 12 hours, 24 hours and 48 hours, respectively. Missouri River stages below Omaha will be impacted, too, but to a lesser degree.

Once the extent of the damage is known, the Corps can develop a repair plan which should be implemented by summer. The goal is to have repairs finished by spring of 2013.

By Jerry Oster, WNAX, Yankton

Filed Under: Accidents & Disasters, Military, News, Weather

Victim identified after fatal head-on crash near Norfolk

May 7, 2012 By

Authorities are releasing the name of the Howard County woman who was killed in a head-on crash early Sunday near Norfolk.

The Nebraska State Patrol says a car driven by 46-year-old Bonnie Stevenson, of St. Paul, Nebraska, crossed the center line about 1:30 Sunday morning on a highway north of Norfolk and hit an oncoming pickup truck.

Stevenson was pronounced dead at the scene.

The pickup’s driver, 54-year-old Eugene Marksmeier of Coleridge, was hospitalized.

Investigators say it’s unclear why Stevenson crossed the line.

Filed Under: Accidents & Disasters, News

Region’s governors may have one more flood summit

May 1, 2012 By

Governors in the Missouri River basin met last summer as record flooding hit the region, a group that was formed at the call of Nebraska Governor Dave Heineman.

Most of the governors agreed flood control should be the top priority of the U.S. Army Corps of Engineers in operating the river system.

Governor Heineman says the governors are still in contact, but they’re not as active as last year.

“We had a conversation a couple of weeks ago,” Heineman says. “At this time, no future meetings (are planned). It looks like we’ve got an opportunity this year that we won’t have a repeat of last year but we’re prepared to act if necessary. I think there may be one more meeting later in May up in North Dakota, just one final look at where we stand today.”

The governors’ group joins a similar one made up of the Congressional delegations from the basin, in asking the Corps of Engineers to modify its management of the river.

By Jerry Oster, WNAX, Yankton

Filed Under: Accidents & Disasters, News, Weather

Federal ag boss blasts Army Corps for flood response

April 25, 2012 By

Acres of swamped farmland in Nebraska & Iowa, June, 2011

U.S. Agriculture Secretary Tom Vilsack says the U.S. Army Corps of Engineers should be more nimble in responding to weather events that impact the agency’s management of the Missouri River.

“It would be well for the Army Corps to be more attentive to the needs and to listen more closely to the concerns along the river systems. I think there’s a tendency for the Army Corps to say, ‘Hey, we’ve got the answer,’” Vilsack says. “You know, you really have to have better dialogue and better communication with folks.”

Farmers and others along the Missouri River have complained about the way the Corps managed the release of water from upstream dams last year — leading to massive, long-term flooding along the river corridor.

Vilsack says the Corps needs to build “more flexibility” into its management plan for the Missouri.

“When they saw record snowfalls and snowpack, there should have been, ‘Hey, how does this fit into our overall strategy and does it still fit and does it still work?’” Vilsack says. “We’re seeing more extreme weather conditions and I think that put the emphasis and a requirement on all of us to constantly rethink whether or not our assumptions were correct in whatever plan we’ve developed.”

Vilsack says the Corps should “be more engaged” in an on-going review of its management plan for the Missouri or any other river.

“Not just well, ‘Well, we’ve done this plan and we’ve put a lot of effort into it and we can park that plan and we can just work that plan because it’s the right plan,’” Vilsack says. “Well, maybe it was the right plan at the time. Who knows? But you now have changing weather conditions and you should be saying, ‘Does this plan still fit?’”

Record flooding hit wide sections of eastern Nebraska and western Iowa last year as the Missouri River pushed out of its banks for much of the summer.

Filed Under: Accidents & Disasters, Agriculture, News, Weather
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