North Dakota Air National Guard helicopter places 1 ton sandbag to stem erosion at Cottonwood Creek Dam at Lake LaMoure on April 19.

The National Guard finished placing 1-ton sandbags at the Cottonwood Creek Dam at Lake LaMoure yesterday [April 19, 2009], slowing the water flow from the eroded spillway.

The Guard had been on site since early yesterday morning, arriving around midnight. Helicopters had been called in after representatives from the U.S. Army Corps of Engineers and the North Dakota State Water Commission observed the quickly eroding spillway.

Residents and officials had been filling the sandbags in the town, and then hauling them on trucks to a site near the dam. From there, the 1-ton bags were hooked up to the UH-60 Black Hawk helicopter on site, which flew to the dam to place the bags in the spillway.

“They’re trying to make a tier system so the water slows down in different pools,” Spc. Anthony J. Keegan, Bismarck, said.

Keegan, an aviation operations specialist with the 1-112th Aviation Battalion out of Bismarck, served as a communications link between the engineers on the ground and the air crew. Information about exact placement of the bags would come to him, which he would radio to the crew in the Black Hawk. Because this required him to stand near the edge of the eroded area, a rope was tied around his waist and attached to a nearby tree, effectively serving as a safety harness had the ground given way.

He said that because the operations were ongoing, 24-hour fueling points had been set up in LaMoure and Valley City.

Capt. Ray Ripplinger, 3662nd Maintenance Company commander and the on-site officer in charge, said spillover had begun early last week. The 3662nd arrived late last week and started patrolling about two miles of earthen dike in the area, as well as setting up traffic control points. In addition, a platoon from the 188th Engineer Battalion was attached to the 3662nd to serve as a quick reaction force. Soldiers in the 188th also operated equipment and staffed traffic control points.

“The second tier was looking good, so the decision was made to stop filling sandbags in LaMoure,” Ripplinger said yesterday afternoon.

Dan Ireland, LaMoure Fire Department fire chief, said it was the second spillover at the dam this year, although the first time had been mild in comparison. He said when he first saw this spillover, it was hard to tell how much earth had been moved by the flooding water.

“The water was running pretty deep, so it was tough to judge how much had been cut away,” he said.

As of Sunday, water had taken the eroded area approximately 40 feet down in places. At that time, about 500 cubic feet per second of water was coming through the eroded area, down from 550 the previous day.

Todd Sando, assistant state engineer with the State Water Commission, said the sandbags were being used to keep the dam from eroding any more, and the different tiers were built to keep water velocity as low as possible.

“If we can use some material to keep some water here, that slows it down,” Sando said.

Another method of taking the strain off the main spillway was to dig a diversion on the south side of the dam.

“The diversion was created to take some pressure off the spillway itself,” he said.

The Guard also brought in 2,000 cubic yards of riprap, which consists of chunks of concrete and stone that is used to help prevent erosion. Dump trucks were unloading the rocky material on the north side of the dam and then private contractors would place the material.

National Guard trucks place rip-rap in temporary dike at Cottonwood Creek Dam at Lake LaMoure on April 19.

“We had bulldozers push them out and the excavator would place them and press them down,” Sando said. “The rock also helps keep the pools in place.”

Refueling caused a temporary halt to tier building operations in the afternoon, but after about another hour of flight time, the final sandbags were placed. That didn’t mean the Guard was ready to head out, though.

“We’ll continue to assist the local officials and monitor the spillway,” Ripplinger said.

North Dakota National Guard
by Spc. Chris Erickson

One ton sandbag being placed to control spillway erosion at the Cottonwood Creek Dam at Lake LaMoure.

One ton sandbag being placed to control spillway erosion at the Cottonwood Creek Dam at Lake LaMoure.

One ton sandbag being placed to control spillway erosion at the Cottonwood Creek Dam at Lake LaMoure.

UPDATE: Link to National Guard photos of work

With stepped-up efforts early this morning, the North Dakota National Guard continues to reinforce the eroding emergency spillway by the Cottonwood Creek Dam at Lake LaMoure, near LaMoure, N.D.

LaMoure County asked for help with the spillway late Saturday night. Sheri Gartner, emergency manager, indicated to the State Emergency Operations Center that the spillway had eroded about 50 feet.

State Water Commissioner Bob Flath used a generator-powered floodlamp to look, and then requested the U.S. Army Corps of Engineers do the same. At 10:22 p.m., the call went out to the North Dakota National Guard requesting the giant, 1-ton sandbags be placed by helicopter.

The Joint Operations Center at Fraine Barracks in Bismarck, the headquarters command element for the Guard’s flood operations, sprang into action. They arranged for a Black Hawk helicopter from Fargo to respond on site, and for a Chinook helicopter to stand by.

“There’s only room there for one helicopter at a time,” said Chief Warrant Officer Curtis Stanley, aviation liaison officer, from Bismarck. Aviators made sure the helicopters had their longest cables, in order to have enough clearance, and sent an aviation operations specialist with a Harris radio to fine-tune the helicopters’ placement of sandbags from the ground. (The Harris radio is a handheld unit that allows a Guardsman on the ground to talk to a helicopter.) The Joint Operations Center also brought a Black Hawk from Minot; it carried two members of the State Water Commission from Bismarck to the dam for a first-hand look.

Planning ahead, the Joint Operations Center ordered the transfer of 13 filled 1-ton sandbags from Fargo and 30 filled bags from Valley City to the dam to add to the 78 sandbags already there. They sent 200 empty sandbags from Fargo to the city of LaMoure’s sandpile to be filled if needed – and that effort is beginning this morning. There were three bulldozers and an excavator from non-military sources already on site, and the Guard sent two more bulldozers.

The first Black Hawk reached the dam at 11:30 p.m. and immediately began placing sandbags.

“They’ll be putting in bags every 10 minutes,” Stanley said at the time.

The operation continued smoothly, and updates on the mission came to the Joint Operations Center detailing the mission:

At 3:40 a.m., the second Black Hawk arrived and set down the commissioners. At that point, the first Black Hawk had placed more than 50 1-ton sandbags.

At 4:15 a.m., a truck arrived from Fargo with 13 full bags and 200 empty bags.

At 4:30 a.m., the bulldozers already on site began pushing rock into the spillway. The National Guard had hauled in 1,200 cubic yards of riprap on Saturday, and plans began to haul as much again today.

At 5:05 a.m., the two extra bulldozers arrived.

At 5:30 a.m. Capt. Ray Ripplinger called in to report from the Cottonwood Creek Dam: Placement of the original 78 1-ton sandbags on hand at the dam was nearly complete. The State Water Commission was encouraged by the results, and requested that the Guard to continue placing sandbags.

In LaMoure, Guardsmen are beginning to use Bobcats to fill the empty giant bags. Two Bobcats use the forklift tines to hold the bags, while the second pair uses buckets to fill them with sand. An excavator then loads the filled bags on a truck. Eighty additional cable slings are on hand at the Cottonwood Creek Dam to connect the sandbags to Black Hawks. (A sling is released from the cargo hook and placed with each bag.)

At 6:20 a.m., Stanley reported that the Black Hawk has refueled three times. A National Guard fuel truck is parked at the LaMoure city airport, six miles from the dam. The night crew that had been flying the Black Hawk throughout the early morning hours changed shifts at 6:30 a.m., and fresh Guardsmen continue to work on site as the operation continues. The Guard will continue placing sandbags at least throughout the day and continue until the mission is complete.

DVIDS
Story by Ann Knudson