Hurricanes Helene and Milton landed a devastating one-two punch to Anna Maria Island’s stormwater infrastructure last year.
And their impact on that infrastructure might reverberate for years to come.
City officials spoke with The Islander over the week of Sept. 29 about how last year’s hurricanes impacted their cities’ stormwater infrastructure and how it might change moving forward.
Last September, Helene brought historic storm surge to the island, submerging much of it underwater.
That rush of water also displaced tens of thousands of cubic yards of sand from the beaches onto the land, leaving many roadways covered in sand and debris after the surge receded.
Following the storm, responders cleared roads with bulldozers and excavators, often pushing the leftover sand into rights of way where many miles of stormwater infiltration trenches across the island are located.
Infiltration trenches are filled with loosely packed stone that allows stormwater to seep through, filtering waterborne nutrients, pollutants and sediment from the water before it reaches local sources.
The trenches are not primarily designed to reduce flooding, but they collect stormwater and often feature underground pipelines to carry the filtered water elsewhere to drain.
While the surge-brought sand has since been removed, the sediment has left many of those infiltration trenches clogged, reducing their efficacy and leaving some all but useless.
In Holmes Beach, city engineer and public works director Sage Kamiya told The Islander Oct. 2 that the first phase of work repairing the clogged trenches on the south end of the municipality has already been completed.
That work includes removing about 6-10 inches of impacted stone from the trenches, replacing it and wrapping it in filter fabric to keep the material in place.
Kamiya said the city plans to complete another two phases of infiltration trench repair work to get the infrastructure back to where it used to be.
While the city will front the more than $2 million cost to complete all three phases, it is seeking 75% reimbursement funding from the Federal Emergency Management Agency to help shoulder the load.
Anna Maria Mayor Mark Short told The Islander Oct. 2 that the city planned to complete “some” infiltration repair work over fiscal 2025-26, but only in areas where localized flooding was “really bad” or where the trenches had been shown to help reduce stormwater buildup.
He said he was not a “fan” of infiltration trenches since people expect them to address localized flooding when they are primarily intended to filter runoff, not drain it.
On the other hand, the city has contracted Sarasota-based C-Squared CGC Inc. to clean out and regrade 11,000 linear feet of swales — shallow ditches intended to collect stormwater runoff and prevent flooding.
Short said C-Squared was set to start work on the swales by the week of Oct. 6.
While last year’s hurricanes resulted in extensive repairs for the two cities’ stormwater infrastructure, they also might lead to changes moving forward.
Short said the city plans to conduct a resiliency study to determine potential solutions for dealing with stormwater buildup and localized flooding down the line.
“I think this resiliency study is going to point us in the right direction. Whether it’s swales. Maybe it’s more pipes and pumps. We don’t know,” he said. “I’m sure we’re going to find out there are better, longer-term solutions.”
For the city of Holmes Beach, Kamiya said last year’s storms could be partly credited — alongside the municipality’s goal to continuously improve upon itself — for changing the way they look at certain projects.
One of those changes involves topping infiltration trenches with soil and sod instead of leaving stone exposed.
Kamiya said topped trenches were better protected from sediment, improving their survivability and maintenance requirements, as well as more aesthetically pleasing.
“I think the community is going to start seeing the infiltration that goes in look a little different,” he said.
Bradenton Beach Mayor John Chappie did not respond to The Islander’s inquiries as of press time.