Posted on July 3, 2018
By Carla Waters, Times-Republic
Because of high expense and no guarantees of success, the Watseka City Council Tuesday night agreed to opt out of an Army Corps of Engineers study on flooding.
This is different than the Department of Natural Resources buyout program, which the city is currently working through.
Mayor John Allhands read from the 2014 compressive plan for the city, which was prepared by Ginkgo Planning and Design Ltd., and Robinson Engineering Ltd.
Most concerns about the Army Corps plan are that the costs are very high for any of the possibilities mentioned and that should the city go ahead with a project like a levee, it would be pushing water on to someone else.
Allhands said of the Army Corps project, “I know that we’ve already kind of done this at the March council meeting, as far as we tabled going in to the Army Corps plan.
Reading from the comprehensive plan, Allhands said, there is an existing flood map. “Discussing the 2008 flood, ‘Days of heavy rainfall and melting snow caused one of the worst floods in recent times in Watseka. About 235 homes were evacuated because of flooding from Sugar Creek and the Iroquois River. The Iroquois River just upstream of Watseka was reported to have crested at 26.7 feet, nearly eight feet past flood stage.
“While impacts of past floods have been significant, most of the city is not within the floodway, but is mostly only in the 100 or 500 year flood plain. Following key points need to be discussed further: most of the flooding is from backwater, not floodwater; some acquisition of flood impacted properties has been undertaken already; downtown and Walnut Street do not flood, well that’s corrected from the last couple of floods, where they had to close off Walnut; major issue: h ones with over 50 percent of structural damage have to be elevated, we know that they also have to be demolished or moved; swamp behind the Ford dealership floods and is an issue; many ownership make it difficult to assemble. Could this be a detention pond and have a storm water management role?”
Allhands went on to say that the swamp area is question is federally protected wetlands, so nothing can be done with that area.
He continued reading. “Flood mitigation involves two broadly connected components that are often lumped together under the same heading of flood mitigation or flood management. 1.) storm water management and 2.) flood plain management. Both of these components involve both management and mitigation. While all flood mitigation strategies are part of flood management in some form, not all management is mitigation. The best flood mitigation is the mitigation that never needs to take place because of previously applied good flood management practices.
“Homes flood so the attempt is made to prevent or to lessen it, that is flood mitigation,” he said.
So, he said, what can be done?
“In a nutshell, nothing is economically feasible. A major and very expensive levee project could be investigated, planned and constructed to protect various areas of the city from flooding. Current cost estimates for such a project are not available but they would be in the multi-million dollar improvement. Monna (Alderwoman Ulfers) I know you were at that meeting. Do you remember what they said?”
Ulfers said, “They said it’s not going to do anything for us, and with that kind of money. The other thing is if we don’t have the money, and we don’t know how much we could get.”
“We’ve heard figures from $5 million to $22 million,” Allhands said. “Correct,” Ulfers said.
Allhands continued reading.
“A common, cheaper alternative is to buy out homes in the flood plain and continue to raze them. This is often more effective at reducing flood damages than a much more expensive levee project.
“Buildings must be elevated to such an extent that they are above the floodplain. Raised buildings or buildings ‘on stilts’ may not be eye-pleasing but they can be kept high and dry. Again, these alternatives can be extremely expensive and not generally well received by residents.
“The question of some sort of regional detention basin has also been expressed in the past, and while this approach has worked for smaller water courses (or water courses with much smaller tributary drainage areas), a 200 or 300 acre-feet regional detention basin would hardly cause a dent in the Iroquois River and Sugar Creek floodplains.
“In summary, the only cost-effective and municipal-friendly flood plain management solution would be to require all new construction to be located outside and above the flood plain.
“Conventional wisdom about water management and storm water detention tells us that the Iroquois River Watershed is so large that small detention ponds should do very little to alleviate the major flooding events when the river cannot convey the volume of water that has inundated the water shed.”
Source: Times-Republic
