Eppley Airfield is waging an all-out battle to keep the airport open against the unprecedented flooding along the Missouri River.
Groundwater has been pooling on airport property and is beginning to encroach on some pieces of important equipment.
Steve Coufal, executive director of the Omaha Airport Authority, said the airport is contracting with seven of the area's leading engineering, technical and construction firms to keep the airport operating.
So far, that effort is succeeding, and the airport is functioning as normal.
However, the river is beginning to show its power — this week's sand boil was a sign of that, he said.
“We know things are going to happen,” Coufal said Tuesday. “The only thing we can say for sure with confidence is that we are going to do everything we can.”
A sand boil occurs when river water forces its way under a levee, percolating up on the dry side.
Crews patrolling the grounds on Monday found a pickup truck-sized boil near the levee. They went to work immediately and repaired it that day, suppressing the boil over an area about 10 times the size of the original problem.
Carlos Lazo, spokesman for the Army Corps of Engineers, said it is not surprising that a sand boil would be found at Eppley.
“These are going to happen because of the added pressure coming from the river,” Lazo said.
The important question is whether the water percolating up is clean or dirty. If it has sediment in it, then the water is causing soil erosion. If the water is clear, it's not.
The Eppley boil brought up sediment when it first appeared, as expected, but in a short time, the water began to flow clear of sediment, said David Roth, director of planning and engineering for the Airport Authority.
During a tour Tuesday, Coufal pointed to areas where problems had developed and explained what was being done to fix them.
Along a ditch in one area, groundwater was pooling near an electrical box and FAA communication towers. Sandbags were placed around the box and towers to protect them, and the water in the ditch was being pumped out toward the levee and back into the river.
Along the back of the terminal buildings, Coufal pointed to sandbags stacked about 2 feet high. He said the sandbags will protect those buildings and other infrastructure during pooling that results from heavy rains.
The bags will keep the insides of the buildings dry for those few hours needed for pumps to pump rainwater from the tarmac.
On Wednesday, water, most likely groundwater, began flowing through a low spot and that was repaired, Roth said.
The seven firms working with the airport are: Kiewit Corp., Alvine Engineering, HDR Inc. and Hawkins Construction, URS Corp., Lamp Rynearson & Associates and Thiele Geotech, Inc.
Among steps the airport is taking:
• Installing a line of 70 wells along the perimeter of the airport and near the river. The wells will go 90 feet deep and pump up river water that is attempting to get to the surface. The water will then be pumped over the levee and back into the river.
Stationed about 500 feet apart, the wells will be capable of pumping about 105,000 gallons per minute back into the river. Stopping river water before it reaches too far into airport property is crucial to preventing sand boils, Coufal said.
• Re-engineering one of the airport pumping stations that previously had emptied into the river at a point below the levee. The airport had to seal that pipe shut and instead reconfigure the station so it pumps water over the top of the levee. Doing so required approval of the Army Corps of Engineers. This station was one of three that the airport has.
• Patrolling the levee every two hours, which is in addition to the monitoring done by the City of Omaha and the Corps of Engineers.
• Sandbagging of airport buildings and about 250 other pieces of infrastructure deemed critical.
• Working with the Corps of Engineers to anticipate problems, develop solutions and have material ready before those problems occur. This is why the airport was able to get the sand boil fixed the same day it was discovered.
Coufal said only time will tell how successful these efforts are.
“We just want to win, when it's all said and done,” he said.
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Sandbagging at Eppley Airfield, as shot by World-Herald videographer Kyle Benecke: