LARGO — One year after construction of a project at the city’s wastewater facility wrapped up, engineers say it is littered with design flaws that have prohibited the system from working properly, and more money and time will be needed to fix it.
Construction of the $19.5 million Disinfection and Effluent Pumping project was completed in April 2018.
Since being placed in operation, however, several problems have developed that were not uncovered during pre-construction testing by the firm tasked with designing the facility, Engineering Services Director Jerald Woloszynski told city commissioners April 2.
“Boy, somebody really missed a whole lot of something here,” Commissioner Curtis Holmes said. “I mean we’re talking about the chemical mixture, we’re talking about the lines, we’re talking about the pumps. This is some pretty major stuff.”
Woloszynski said the project had several objectives.
The first was to comply with a Florida Department of Environmental Protection consent order that states the city must ensure treated wastewater meets certain water quality standards. So, in order to reduce the disinfection byproducts being discharged to Tampa Bay, the city replaced the chlorine gas system with one using liquid chlorine and peracetic acid, a wastewater disinfection alternative that has gained attention in the past decade for being cheaper and better for the environment.
The project also intended to increase the capacity of the effluent pumping system to meet growing demand in the future.
After a year of trying, the acid pumping systems just won’t work, leading the city to pay $200,000 to a new consultant to find out what went wrong and create alternatives.
“This is extremely disappointing to the Engineering department overall,” Woloszynski said. “The pilot testing that tested the peracetic acid proved to be insufficient to scale to the level and permit compliance that we were looking for. At this point, it’s an unpleasant statement to make, but the design for the peracetic acid was not correct and we’re working with the Environmental Services department to come up with an alternative disinfection process.”
Some of those design flaws include channels in the disinfection tank that don’t provide adequate mixing of the disinfection chemical, and pumps that can handle the projected peak flow of approximately 41 million gallons per day, but can’t operate effectively at the lower current average flow of around 12 million.
Also, staff have determined that the required dosage of acid is much higher than expected, making it too expensive to be viable.
“It’s finding that balance between being completely compliant with our permit and a cost-effective matter, Woloszynski told Tampa Bay Newspapers on April 5. “In this case, we can’t achieve either of those, no matter how much peracetic acid we put into our flow for disinfection.”
Woloszynski said Greeley and Hansen, a Tampa-based environmental engineering firm that was paid $4 million for its work on the project, conducted pilot testing of the acid using a portable tank at the wastewater treatment facility, but the city hasn’t been able to replicate the results on a larger scale.
“In that test mode, they saw the adequate disinfection rates that we were looking for,” he said. “The challenge was once it scales up to our actual disinfection tank in the plant. Obviously, either the way the water flowed through the tank or the way it was exposed possibly to sunlight or other different things to that effect, the acid just did not have the effective kill rate that the pilot test did.”
Woloszynski isn’t the only one disappointed with the outcome.
After pouring more than $80 million into several initiatives to cut down on sewer overflows and improve wastewater standards, City Commissioner Jamie Robinson said it feels like the projects are becoming a money pit that need more and more cash each month.
“It’s really frustrating to see this continue to come back, especially with something like this where it’s just not working,” he said, emphasizing that the $200,000 for the new consultant, McKim & Creed, is just for the study and not the implementation of any recommendations.
City Attorney Alan Zimmet said the city is also considering the possibility of filing a lawsuit against Greeley and Hansen, but the study must be done first and the process would be lengthy.
“This is the first step toward seeking that legal recourse,” he said. “We need to know what’s wrong and what the fix is, so we need to bring in another engineer in order to do that.”
Woloszynski also pointed out the city still has an open contract with Greeley and Hansen, so it does have the ability to make any corrections to the design.
Whatever fixes are needed, they must be done quickly, though.
The FDEP consent order expires in October 2022, so Woloszynski said the goal is to move fast without cutting corners.
He said the Environmental Services department is already doing some preliminary testing on alternative chlorination methods, so the consultant can review it and expand the study.
“We have to move with great vigor to make sure that we’re coming up with not only the correct method, but also to implement the correct method prior to the expiration of the consent order,” he said.
He added that the project has not been a complete failure thus far, because it has allowed the city to move away from using hazardous gas chlorine to a liquid chlorine, which is still effective.
“Whatever disinfection method we use, what comes out in our effluent is fully dechlorinated unless it is going into our reclaimed water system,” he said. “Basically, what comes out of our wastewater effluent is clean, clear chemical-free water going into Old Tampa Bay.