The largest single public works project in Winter Springs history is now down to two possible designs.
At the Feb. 14 City Commission meeting staff from Carollo Engineers presented two plans that the city will choose from to build its new wastewater treatment system, replacing an aging system that recently had to undergo emergency repairs.
“This project represents the single largest investment that this city has ever made,” Mayor Kevin McCann said.
City Manager Shawn Boyle said that an estimate of the system’s cost wouldn’t be available until early 2023, though Mayor Kevin McCann in December said it would be “somewhere in the area of $60 million.” Boyle said that he’s seen price swings of 30% or more on a daily basis for some materials, contributing to the absence of a current estimate.
The city initially faced six choices for wastewater management systems, but a selection committee narrowed that to two: a biological nutrient removal (BNR) system similar enough to the city’s current system that it would not require additional training for city staff to operate, or a higher tech membrane bioreactor (MBR) system that can operate out of a smaller facility while producing treated wastewater “of a very high quality.”
Both are systems that use broadly available technology that’s been widely adopted at other cities across the country. The BNR system is more common, according to Carollo Engineers – the firm the city hired to revamp its wastewater treatment system.
“We can treat the wastewater to an exceptionally high level using tried and true methods that are readily available,” Carollo engineer Brian Graham said.
“With BNR the only drawback is it takes a little more space to do the job,” he added. “With MBR, what you see is the same structure, it’s just a little smaller. It works great. It costs a little bit more money because of the membranes you have to buy.”
The MBR system would allow more automation of the process, he said, but would require more training to operate.
In light of the physical deterioration of the city’s current wastewater plants, which have been in operation for more than 40 years, Commissioner Matt Benton was concerned about longevity.
“The physical structures should last 50 to 100 years,” Graham said. “Mechanical equipment, 25 years to 35 years. Things like the filter media, the membranes, they need to be replaced on a 5-to-10-year cycle depending on how aggressively they’re treated.”
The next step is an analysis by Carollo’s engineers to determine the final choice, including discussing priorities with the city.
“We’ll do our due diligence and lay these out and bring to you the reasons why one is selected over the other,” Graham said.
The project’s finalist is expected to be presented to the Commission in March.