Published January 07 2012
Diversion Discussion: Levees, floodwalls alone won’t protect Fargo-Moorhead
For instance, dissenting residents have challenged the Army Corps of Engineers and local leaders to consider building levees and floodwalls instead of building a diversion, and they question why levees aren’t a preferred option.
After all, levees worked in Grand Forks after the devastating flood of 1997, they say.
Following that disaster, eight miles of levees and floodwalls – at a cost of more than
$400 million – were built along the banks of the Red River dividing Grand Forks and East Grand Forks, Minn.
The levees protect against a river level of 60 feet, and the floodwalls were built 3 feet higher than that.
Kindred, N.D., resident Joan Braaten-Grabanski was one of many to write the corps last summer, asking the agency to explore other alternatives, such as Grand Forks’ solution.
“By deepening the river, purchasing structures along the river, and building a greenway/
floodway, you can achieve the results that the F-M area is looking for,” she wrote. “If this strategy was effective for Grand Forks, there is no reason why it can’t be effective for the F-M area.”
But initial technical analysis led corps engineers and Fargo-Moorhead leaders to disagree, which is why the idea of building levees was removed from further consideration early in the process.
In the first months of study in late 2008 and early 2009, levees and floodwalls were among several alternatives being considered by the corps.
Each option was weighed for effectiveness, potential impacts, costs, risk, mitigation and cost effectiveness, among other factors, according to the corps’ final feasibility report.
Levees were initially deemed to be an economically feasible option, but then the historic flood of 2009 struck, changing everyone’s perceptions of how massive “the big one” could possibly be.
After further analysis by the end of 2009, the idea of levees fell short compared to constructing a diversion, in terms of cost effectiveness, annual benefits and residual damages.
A levee system along the Red River simply wouldn’t provide the same level of protection or the same bang for the buck as s diversion would, according to the corps’ evaluation.
In explaining why levees were removed from the list of alternatives, the corps wrote that the protection levees could offer failed to live up to the standards set by Fargo-Moorhead leaders.
In the study’s early phases, the Metro Flood Study Work Group – a committee of local government leaders charged with providing direction on the study – told the corps it wanted protection against a 500-year flood event.
No levee system could measure up to that and, therefore, “such a plan would leave unacceptably high residual risk,” among other lingering challenges, the corps stated.
Implementing a levee plan would also mean the daunting challenge of removing more than 1,000 structures from the urban flood plain along the river, the corps said.
But the question remains: If it worked for Grand Forks, why not Fargo?
Simply put, it’s all a matter of topography.
“The Fargo area lacks high ground to begin and end levees, and that limits the potential levee height,” the corps explained in its response to submitted comments last summer.
“The largest cost-effective levee plan could only be certified up to (a 100-year) event,” the corps stated. “This left an intolerable level of remaining risk, so the levee alternative was dropped from consideration as a stand-alone alternative.”
As Fargo residents well know, that doesn’t mean no levees will be used in the course of shoring up metro-area flood protection.
Fargo leaders are in the midst of a multiyear process to build up protection along the city’s rivers and drains to fend off a flood of up to 42.5 feet on the Fargo gauge.
The initial list of projects was estimated to cost about $109 million when city leaders adopted the goal last spring.
The plan is meant to eliminate the need for sandbags where possible and to build all levees to levels that can be certified by the Federal Emergency Management Agency.
But the city’s 52 miles of dikes are meant to work in cooperation – not in lieu of – the Red River diversion once it’s constructed.
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