MANSFIELD — City council heard possible solutions to an issue that’s plagued numerous residents and business owners over the years — flooding.
City Engineer Bob Bianchi and Miles Hebert of EMH&T discussed the nuts and bolts of the Touby Run Flood Hazard Mitigation Study on Tuesday night. The discussion began at North Lake Park and then later in more detail in council chambers during a public utilities committee meeting.
Both were excited to present what they believe could be the answer to a “very old, complicated and expensive” problem, Bianchi said.
Read more about flooding in Richland County here.
“The flooding that occurs in downtown Mansfield is not coming from Rocky Fork,” said Hebert, project engineer for the mitigation study. “It’s actually coming from an overflow that occurs from Touby Run and fills this really low, we call it a bowl… So if we can come up with an aggressive solution for flood reduction along Touby Run, we can address this flooding.”
A previous study has been revised to include such solutions as creating detention basins at North Lake Park and South Park, replacing bridges on Sixth Street and Mulberry Street and eliminating the Miller Street bridge, and constructing a small embankment at 309 N. Main St.
As part of the proposal, a dam that’s about 900 feet long would be constructed at the west end of North Lake Park, including a concrete spillway. “At maximum height over the stream would be 45 feet,” Bianchi said.
By state regulations, the dam would be have to be Class 1.
“That’s considered a high-hazard dam,” Hebert said. “That’s not a scary thing — that just means we have to do certain things differently and we it means we have to pass a lot of water over that emergency spillway, requiring the construction of what we call a labyrinth weir, in order to pass that amount of water.”
A storm of “biblical proportions” would have to occur in order for water to come over the spillway, Hebert said. That translates to 26 inches of rain in 24 hours.
“Our target design storm is more in the order of six inches,” Hebert said. “That’s the 100-year event. That’s the event you folks experienced in August of 2007.”
Most of the dam sits on city-owned property. However, a small portion extends onto private property, including two Elmwood Drive homes, which would need to be acquired by the city if it chooses to move forward with the proposal.
Below is a cross section of the Touby Run channel through downtown Mansfield during a 100-year flood.
By definition, the term “100-year flood” is used in an attempt to simplify the definition of a flood that statistically has a one percent chance of occurring in any given year. Mansfield experienced a 100-year flood in August of 2007 when it rained about seven inches over 14 hours, devastating hundreds of homes and multiple businesses.
“Our charge is to try to get that red line, that flood elevation, and bring it down as close as we can to that overflow point if we’re going to solve that downtown flooding problem,” Hebert said.
Making floodplains disappear is very difficult, he said.
“We’re not making water disappear here; we’re just managing it differently than it is today,” he said.
The new floodplain would be very shallow in comparison to the current one, Bianchi noted.
“There were a number of structures that were on the fringe of our new floodplain, but all but four of them are out of the floodplain,” Hebert said.
Two of them would be in the floodplain by a couple tenths of a foot, he added.
Further, 106 acres of land and almost $15 million of building valuation would be removed from the floodplain. There would also be a 47-percent reduction of 100-year flood peak discharge value.
The project is estimated to cost $13.7 million. The city could apply for grants to help fund the project, including up to $2 million from the Federal Emergency Management Agency Pre-Disaster Mitigation Grant Program, which is administered by the Ohio Emergency Management Agency.
Local funding would be determined using a project-specific funding program with equivalent residential unit-based fees that may vary based on direct and indirect benefits of the project.
“This is a typical way of trying to figure out how to use a measure of storm water runoff to assign fees to businesses and homeowners in order to pay for projects,” Hebert said.
Estimates show that a homeowner living within the Mansfield corporate boundary would pay $7.20/year, a homeowner living within the Touby Run watershed would pay $26.40/year, and a homeowner living within the 100-year floodplain area would pay $92.40/year. Fees fluctuate depending on ERUs.
One option under consideration is incorporating the fee into a person’s utility bill.
Before concluding the presentation, Bianchi shared an idea that could be pursued, given that the Richland B&O Trail would need to be rerouted around the new dam if the project were completed.
“The dream would be to extend the bike trail to the downtown and open up some areas near the (North Lake Park) dam and this corridor,” he said.
The trail would be rerouted behind the Mid-Ohio Conference Center and around the dam to reconnect with North Lake Park.
Various opportunities exist to create more spaces for activities in the city, Bianchi pointed out, including soccer fields, basketball courts and community gardens.
There’s no legislation for the floodplain project at the moment; however, Mayor Tim Theaker said that it could be drafted by August or September for council’s consideration.
The whole project would take about four years to complete.
Third Ward Councilman Jon Van Harlingen, who chairs the utilities committee, said he would like to speak with the constituents about it.
“I believe the more input we can get the better,” he said. “This is not something that we have to do, but it could be very beneficial for the future of the City of Mansfield.”
Fourth Ward Councilman Butch Jefferson sees this as a great opportunity for the city.
“We gotta dream,” he said. “We gotta look 30 and 40 years out … In the long-term it’s really going to benefit the city.
“I say go.”
Councilman-at-large Cliff Mears echoed Jefferson’s comments, saying, “It’s incumbent upon us to look at the future.”
“Climate change, to me, is real and things are going to get worse weather-wise,” said Councilman-at-large Don Bryant, who’s vice chair of the utilities committee. “We’re going to expect more rain and flooding.”
Sixth Ward Councilwoman Garnetta Pender, a member of the utilities committee, urged action, remembering what happened to the church she attends in 2007.
“We had four feet of water inside the church and had to redo the whole lower level,” she said.
“I think we have waited long enough. We need to do something. As a representative of the city, I’m all for it.”
