09-106 FLOOD FEATURE: Slowing Spillover at Cottonwood Creek Dam from Three Directions
By Spc. Chris Erickson, NDNG Public Affairs
/ Published April 20, 2009
LAMOURE, N.D. -- The National Guard finished placing 1-ton sandbags at the Cottonwood Creek Dam at Lake LaMoure yesterday, 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.
"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.
View photos of yesterday's mission on our Flickr site: http://www.flickr.com/photos/ndguard/sets/72157616972309345/.
Since the terrorist attacks on America, the North Dakota National Guard has mobilized more than 2,800 Soldiers and more than 1,600 Airmen in support of the Global War on Terrorism. In recent weeks, nearly 2,000 North Dakota National Guardsmen -- with support of about 400 additional Soldiers and Airmen from six other states -- have been mobilized for current flood fighting missions all across North Dakota. With a total force of about 4,400 Soldiers and Airmen, we continue to have sufficient forces available to provide emergency response and homeland defense.
Photos by Senior Master Sgt. Dave Lipp, 119th Wing, North Dakota Air National Guard. High-resolution photos available on our FTP site (navigate to the LaMoure folder -- ftp://ftp.state.nd.us/2009_NDNG__flood_ops/Lamoure/090419-LaMoure/):
FTP Server: ftp://ftp.state.nd.us
Password: PIO2493 (case-sensitive)