By DOTTY NIST
WALTON COUNTY, FLORIDA – Approval was recently granted for emergency repairs in response to the failure of a retaining wall that had been part of the Oyster Lake bridge project.
At their June 27 meeting at the Walton County Courthouse, the Walton County Board of County Commissioners (BCC) approved funding to pay for the repairs.
Oyster Lake is a coastal dune lake on CR-30A in the Dune Allen area with outfall to the gulf. The bridge project completed two years earlier had included the demolition of an existing concrete box culvert on CR-30A, construction of a new concrete bridge on the county road, a new outfall channel connecting Oyster Lake with the gulf, and a vinyl sheet pile wall.
Engineer Chance Powell of Walton County Public Works appeared before the commissioners at the June 27 meeting, explaining that late on the night of June 23, the water elevation in the lake rose to approximately five to six feet above sea level, with the gulf at a dead low tide, and that the lake had opened, overflowing the outfall channel and resulting in failure of the wall.
Powell said that public works had already done some work in response to the situation but that they would like to address it in a more permanent fashion.
He said that the lake level had gone down but there was currently an influx of gulf water, resulting in the material on the north side of CR-30A becoming damp, presenting a potential problem in the event of rain.
He said, “30A is in jeopardy.”
Powell recommended the construction of a new sheet pile retaining wall from the existing bridge on CR-30A up the south side of the channel to harden the area. He estimated the cost to do that—along with some other improvements such as guard rails to improve safety of vehicles pulling off the road at night—at approximately $250,000.
In response to a question, Powell said that a contractor would need to be enlisted to construct the retaining wall, since public works does not have the equipment to do the work.
The commissioners voted 4-0 to declare an emergency situation. Funding for the repairs was discussed, and Walton County Finance Manager Melissa Thomason indicated that sufficient funds were available in the public works contingency account.
District 3 Commissioner Bill Imfeld moved to approve the use of those funds, with BCC discussion continuing.
District 1 Commissioner Bill Chapman expressed concern about the amount of funds expended in the 2014 project and for additional funds now being required to address problems in the same area.
He asked about the source of the water causing the overflow situation.
Powell responded that this had been water in the channel and not from road runoff.
Cliff Knauer of county engineering consultant Preble-Rish told the commissioners that the existing wall had been exposed by eight to nine feet when it had only been designed to be exposed approximately three feet.
This had been the result, he said, of the April 2014 100-year storm event that had taken out 22,000 cubic yards of sand from the outfall, with much of that material coming from north of the bridge.
Knauer said that after that storm, “the channel was never properly stabilized.” He said that under those conditions he was surprised that the existing wall had held as long as it had.
He said that for some time he had been working to get permit modifications approved in order for the lost sand to be replaced and stabilized. He expected that work to be permitted in time for work to begin in November, following sea turtle nesting season.
The commissioner approved 4-0 the motion to fund the new retaining wall and other improvements as requested by Powell.
Due to the emergency situation, he was authorized to proceed with obtaining quotes from several contractors in order to expedite the wall project.
On June 5, Walton County Public Information Officer Louis Svehla stated that a restoration plan had been developed in connection with the project and had been given to three contractors with a request for quotes.
“Quotes are due tomorrow by 3 p.m. Construction should start before the end of July,” Svehla reported.