Keeping the 'Red' out: working together to protect sister cities from floods.
Nearly 100 inches of snow were left behind after seven blizzards blew through in winter 1996-97, resulting in significant flooding during the spring melt. The area's extremely flat topography and ice jams created by the river's northerly flow into frozen waters exacerbated the problem. Water reached the 28-foot flood level on April 4. The river continued to rise for 17 more days, ultimately cresting at 54 feet--26 feet above flood stage and 2 feet above the tallest emergency flood-protection levee.
Floodwaters engulfed the cities as levee after levee was overtopped. A massive evacuation was necessary with 90% of East Grand Forks' 8700 residents and 75% of Grand Forks' 52,000 residents forced from their homes. An electrical problem sparked a fire that damaged or destroyed 11 buildings in Grand Forks' historic downtown. When the waters receded, the magnitude of the destruction was overwhelming and the devastation received national attention. More than 20,000 volunteers poured in to assist with cleanup. Donations were contributed from across the country.
Following the flood, both cities began working aggressively with the U.S. Army Corps of Engineers, St. Paul District, to develop a permanent, comprehensive flood damage reduction plan to assure that 1997's flood devastation never has a sequel. The Corps completed a general reevaluation report and environmental impact statement. Several alternatives were evaluated, including construction of a large channel to divert floodwaters around the cities. In the end, the cities decided to keep the river on its present course, vacate the river's floodplain and convert it to recreational use, and protect the cities from future flooding through construction of 30 miles of levees and floodwalls.
"It was very hard for people to make life-altering decisions right after the flood," said Bonnie Greenleaf, project manager with the Corps, St. Paul District. "It was necessary to decide where to draw the line to place the levees. We were proposing to move the levees further back from the river. Whole neighborhoods wouldn't be allowed to rebuild. It was extremely traumatic for people. When they had already lost so much they didn't want to lose any more," she said.
FLOOD PROTECTION PLAN
The Corps developed a comprehensive flood protection plan consisting of levees and floodwalls that create protective rings around both cities. The plan included stabilizing an existing dam, removing a railroad bridge, closing numerous roads, extending and expanding an existing diversion channel, and constructing a new diversion channel. The design level of protection was equivalent to the peak discharge experienced during the 1997 flood.
"Our saving grace was that the federal government came in with a large grant for the city ... these moneys were used to help with flood recovery and to purchase numerous homes along the route of the new levee, as well as homes on the wet side of the levee," said Mark Walker, Grand Forks' assistant city engineer. "We had a pretty strong congressional delegation. That was helpful in securing the funding and the commitment for building the permanent flood protection system."
"Once emergency appropriations were received, things moved quickly," said Greenleaf, who has been with the Corps for 17 years. "We developed an aggressive schedule that calls for completion of the project in 2006." The Corps contracted with several engineering firms, including Stanley Consultants, Minneapolis, to provide detailed engineering services to help complete the project.
"Stanley Consultants, the Corps, and the city have worked well together," said Walker. "It's interesting having the three entities work together on a project and bring three different perspectives on how a project should be developed. It's been very successful in terms of getting the project off the ground quickly and constructed at a fast pace."
The work of building the floodwalls and levees that protect Grand Forks from the Red River was divided into four phases, each consisting of numerous reaches. Design and construction of the floodwalls and levees proceeded according to the ability to acquire the property and protect areas most vulnerable to flooding. Grand Forks now has 51,620 feet of levee, 8890 feet of floodwall, and 12 pumping stations, with a total pumping capacity of 361,000 gallons per minute. Eleven closure structures allow pedestrians, vehicles, and trains to pass through the flood barrier when there is no flood.
The design foundation provided by the Corps was solid, but several cost-saving ideas were incorporated during the final design process. Changes proposed by Stanley Consultants and accepted by the Corps and the city of Grand Forks included eliminating a pump station while still providing better overall flood fighting operation, bringing a section of the levee into play in an existing municipal golf course, and using a levee constructed of traditional earthen sections and mechanically stabilized earth walls instead of concrete flood walls.
The project also led to a solution for another problem. Before the flood protection project, Grand Forks had no available space to build stormwater treatment basins to meet new U.S. Environmental Protection Agency NPDES Phase II stormwater regulations. But now, ample room was available in the new greenway, and excavation of the storage basins provided earth fill needed for levee construction. These innovative features will treat the majority of Grand Forks' stormwater. Prior to this time, the runoff went directly to the Red River from nearly all parts of town.
Construction of the $410 million project began during summer 2000 and is currently 75% complete. The federal and local governments share the project design, real estate acquisition, and construction costs. Operation and maintenance costs will be the responsibility of the two cities.
DEVELOPING A GREENWAY
As another side benefit of the flood control construction, Grand Forks and East Grand Forks have taken the opportunity to develop an extensive park system, or greenway, that draws people to the river. "For some time, the Corps and the Federal Emergency Management Agency have said not to build next to a river. Leave a buffer zone for recreational purposes and for Mother Nature to flow," said Walker. "We have been able to do that."
The low-lying homes inside the flood-plain boundary, most of which had been damaged by floodwaters, were purchased and removed. Approximately 2200 acres in Grand Forks and East Grand Forks were converted to a greenway, which serves the dual purposes of mitigating floods and enhancing quality of life. Approximately 800 acres in Grand Forks were converted to parks, picnic and playground areas, a camp-ground, golf courses, sledding hills, shore bank fishing sites, rock dams, and more than 14 miles of bike and pedestrian trials. A tribute to the former Lincoln Park neighborhood, which had 100 homes destroyed by the 1997 flood, can be found within the greenway. A key feature in the downtown area is a flood memorial--an obelisk indicating all of the great Red River floods. The top of the obelisk is at the elevation of the 1997 flood.
The teams prepared the cities to combat a second major flood. The odds that another flood of this magnitude will occur before construction is complete are small, but residents keep a close eye on the river each year as the snow begins to melt. "Spring floods are my biggest challenge," said Walker. "This spring the river was swollen again, to the point where we had to activate several flood pump stations built during the project.
"As we look to the future we recognize that previous flood fights have been the community fighting floodwaters with sand bags in residential back yards and installation of numerous gasoline powered portable pumps. We now have a more permanent solution of fighting floods with levees and control operated flood pump stations in place," said Walker. "Best of all, the system will be built to a higher elevation than the height of the '97 flood. It provides some peace of mind for many people."
--Johnson is vice president and senior project manager with Stanley Consultants, Minneapolis.
RELATED ARTICLE: Saving St. Anne's
The location of the historic St. Anne's/St. Michael's hospital building near a potential landslide area prevented building either a levee or a floodwall between the river and the historic building. Demolishing the building to make room for the levee appeared to be the only option. But no one involved with the project wanted to lose the building, especially since it had recently been rehabilitated into a home for Grand Forks' senior citizens.
"That was a trying time for us," said Mark Walker, Grand Forks' assistant city engineer. "Numerous people worked hard to save the building when it was an empty abandoned shell. It was converted to senior housing prior to the flood. Now that it had been rehabbed, it was a much tougher decision to tear it down. There was a problem associated with every alternative that would save it. It seemed like the wrecking ball was the only option."
The city asked the Corps to take one last look at how the building could be saved. At the last minute, Stanley Consultants developed a solution that saved the building, provided the residents with a new amenity, and cost less to construct than any other alternative previously presented.
The approach called for a floodwall that looks like a porch. The floodwall will protect the building and provide level access to the residents who want to sit outside and watch the river. This solution also resolved a firefighting safety issue, since it allows access to the balcony through a window, allows firefighters use of the balcony during a fire, and won't trap firefighters in the event of a building collapse.
The Grand Forks Historical Commission reviewed and approved the concept's details. "It was an excellent solution that saved a historically significant building," said Walker.
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|Title Annotation:||Stormwater control|
|Date:||Sep 1, 2005|
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