How can Manatee County prevent Centre Lake from flooding? Build a wall, study says
Commissioners may have finally discovered a solution to the Centre Lake subdivision’s devastating flooding problem.
Following an unusual storm event that flooded homes so badly that it prompted a visit from Bryan Koon, former director of Florida’s Division of Emergency Management, residents approached the Board of County Commissioners and demanded they figure out how to fix the issue.
CDM Smith, a contracted consultant, and county staff are now wrapping up study nearly three years in the making that focused specifically on remedying issues in the 61-home community off of Prospect Road in south Manatee County. It was a tougher challenge than engineers expected.
“This proved to be a very difficult challenge to provide regional benefit and solve problems in Centre Lake,” said Benjamin Pernezny, a civil engineer with CDM Smith.
Engineers studied the entire 11 square-mile Pearce Drain watershed, and used a scientific rain model to predict the effectiveness of several projects that could help the neighborhood withstand extended rainfall.
Of the 14 projects that the study considered, most of them didn’t remove many structures from flooding perils. Even if the county purchased each home, demolished them and turned the area into a giant stormwater pond, regional flooding would still be a problem, Pernezny explained.
Some other options included building more stormwater ponds along Tallevast Road or expanding the Pearce Drain channel by 50 feet, but those didn’t result in satisfactory improvements, especially given the possible price tag up to $56 million.
The proposed project with the highest probability of success, however, would fairly straightforward: Building a 4-foot-high flood wall around the 16-acre subdivision and elevating 65th Avenue East, the entry road into the neighborhood.
It’s also the cheapest option at $8.4 million, of which the county would only have to pay half if its cooperative funding initiative request is approved by the Southwest Florida Water Management District. If Manatee goes that route, all 61 Centre Lake homes would meet the county’s guidelines.
“This is the one that does the trick,” Pernezny told commissioners.
But the mention of a flood wall immediately drew comparisons to the infamous breach of New Orleans’ levees, which are similar flooding barriers, when Hurricane Katrina struck in 2005.
“We’ve got interesting solutions here, but I’m concerned about a flood wall,” Commissioner Vanessa Baugh said.
“I’m hesitant,” Commissioner Priscilla Whisenant Trace added. “I’ve always been taught to let the water go where the water wants to go.”
According to the Federal Emergency Management Agency, floodwalls are more durable against erosion but come at a higher cost.
County staff, however, is confident that a flood wall is a viable option to prevent homes from flooding. Sia Mollanazar, an engineer with the public works department, said board members are right to worry, but the model shows that the water that would be prevented from entering Centre Lake wouldn’t flood any other homes in the area because they were all built at higher elevations.
Mollanazar urged the county to consider moving forward with the flood wall option to answer the demands of the Centre Lake community.
“Your other option is to buy 61 homes. When you really sit down and think about it, I’m with you, I’m a public servant,” he said. “These people didn’t do anything wrong other than raise some money for a down payment and go buy a house. At the end of the day, you’ve 61 families in limbo and you’ve got to put yourself in their shoes. It’s a personal opinion, but I think we have some obligation.”
The plan might sound good on paper, Commissioner Betsy Benac said, but it could run into even more challenges when it comes time to be permitted by SWFMD.
“I guess it’s just my experience, having worked for a civil engineering firm for 18 years. I love the fact that you guys say this is all going to be simple, but I know what SWFMD’s rules are. It is not simple,” Benac pointed out. “To take the property out of the 100-year floodplain and affect all these other properties that have been permitted with water management systems, I don’t necessarily see that as simple.”
Regardless of the issues, Commissioner Misty Servia, argued that the board must move forward to improve quality of life for residents.
“Everybody agrees it’s not simple, but we are on the right path,” she said. “There are challenges, but we’ll find ways around them.”
County staff have not officially recommended the flood wall option but are pursuing the 50-50 funding agreement with SWFMD. Staff also noted that the $8 million project could be funded quickly if commissioners vote to approve the more expensive tier of the upcoming stormwater fee.
This story was originally published November 2, 2019 at 5:00 AM.
