Stormwater | Project Profile

The spring of 1997 brought disastrous flooding to communities along the Red River. Several factors–the weather, the topography, and the direction of the river itself–contributed to the magnitude of the problem. Efforts that began after the ’97 floods helped mitigate some of the damage when the river rose again this past April.

The river flows north between Minnesota and the Dakotas, through Winnipeg in Manitoba, and then into Lake Winnipeg, ultimately discharging to Canada’s Hudson Bay. The river lies in the basin of the ancient Lake Agassiz, which formed during the last glacial period and covered thousands of square miles in northern Minnesota and North Dakota. Much of the water from the glacial melt went south, scouring out the Minnesota River Valley and helping form the upper Mississippi River. As the glacier melted, the water in Lake Agassiz drained, and the area became the "Red River Valley of the North."

The valley is almost completely level, with elevation varying only a few hundred feet from the point near Breckenridge, MN, where the Red River is formed by the confluence of several other rivers, to the Canadian border. "This is a very flat area–it’s the bottom of an old lake. We don’t have a river cutting through a gorge. If the water level comes up a little bit, it can travel a long distance horizontally before it stops," explains Terry Estenson of Northwestern Power Equipment Company in Roseville, MN, who has been heavily involved with the mitigation efforts of the last few years. "Right now the Corps of Engineers is building dikes along the river through Grand Forks, Crookston, Fargo, Moorhead, and farther north. We were involved in putting pumps all along there."

Seven major blizzards and heavy snowfall throughout the watershed in the winter of 1996-97 led to heavy runoff in the spring. When the spring thaw hit the lower portions of the watershed, the northern portion was still frozen, unable to accommodate the immense volume of north-flowing water. "The water that melted in our area just stayed there," recalls Estenson. Flooding exceeded predictions from hydrologists and the US Army Corps of Engineers as waters rose to record levels and stayed there for six weeks in some areas. "There were places where you could get up on top of a freeway overpass, right by Grand Forks, and when you looked out, it looked like an ocean. The water was probably only a foot deep, but it covered miles."

Prompted by previous flooding, the City of Winnipeg constructed the Red River Floodway, a nearly 30-mi.-long channel along the city’s eastern edge, in the 1960s. Sometimes called the "billion-dollar ditch," it was a controversial project at the time. "When they built it, some people thought it was a waste of money," says Estenson. "But when they had this big flood, it probably saved the city from billions more in damage. It looked awfully smart then." However, a similar solution for every city along the Red River is not practical or financially feasible.

The Army Corps of Engineers, along with several consulting engineering firms, spent the year following the floods designing and building higher levees and some bypasses for the communities along the river. Many neighborhoods have been razed to make room for higher and wider levees. Most communities are enhancing their dike and stormwater systems by installing permanent pumping control structures.

"When the river’s very high, it can be 15 or 20 feet above the normal ground level," Estenson notes. "If they have spring rain of half an inch or an inch, normally the rainwater would have come into the river. But since the river is higher than the storm sewers, they pump it from the storm sewers up into the river."

A typical pumping structure consists of a manhole with a divider, a sluice gate, and a pump on the stormwater side to pump water over the dike to the river side. During the spring when the river is at flood stage, the floodgates close to isolate the river from the storm sewer, and the automatic pump station handles any snowmelt or rainfall. Low-profile pumps from SRS Crisafulli, 3-4 ft. shorter than some vertical propeller pumps, have been used along the tops of many of the dikes. Breckenridge alone installed more than 20 permanent pumps, with performance ranging from 5,000 to 10,000 gpm at heads up to 25 ft. In such cities as Moorhead, the pumps were installed throughout residential neighborhoods. "Not everybody wants one in their backyard, but they realize if it weren’t there, their yards would be flooded," observes Estenson.

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