Construction to Blame for Overflow at St. Pete Sewer Plant, Officials Say
The Southwest Water Reclamation Facility has two projects ongoing. One is an expansion. The other is a biosolids to energy project.
ST. PETERSBURG – About 50,000 gallons of “mostly treated” wastewater overflowed at the Southwest Water Reclamation Facility on Wednesday (July 12)
According to plant personnel, heavy rains caused an increase of water into the facility and – because of the ongoing construction – the decreased capacity of the chlorine contact basin, which is the final step in processing the reclaimed water, allowed some of the effluent to splash out.
The water breached the sides of the chlorine contact chamber, moving into a swale area. Contrary to early reports, it never reach the onsite retention pond. The spilled wastewater was already being treated prior to the breach, so no other disinfection was necessary.The overflow at the plant, 3800 54th Ave. S, happened between 8:50 p.m. and 9:10 p.m.
There was no discharge of any water from the plant property. Nor have there been any incidents of raw or untreated wastewater reported. Since the initial reporting of what, officials said, amounts to less than two swimming pools’ worth of water seeping into the ground around the basin (which has been well churned up during the on-going construction at SWWRF), Public Works Administrator Claude Tankersley issued these statements to clarify and detail the event:
“We had close to two inches of rain in one hour that doubled the flows from the Southwest Water Reclamation facility from approximately 20 MGD [million gallons per day] to 42 MGD within 45 minutes.
“This resulted in a short-term wave of water surge through the plant that would normally have been fully handled. However, because of the plant being under construction, half of the chlorine contact chamber was out of service for expansion during our fast-track construction.
“The fast-moving nature of the plug flow of water caused 50,000 gallons of treated chlorinated water to spill from the chlorine contact chamber. The spill occurred on the SWWRF plant site where it was fully contained on site.
“We have no reports of discharges of raw or untreated wastewater anywhere in our system.”
Tankersley said the overflow will serve as a valuable learning tool for the future.
“In consulting with construction manager Haskell, we are closely evaluating the event to determine how we will manage future fast-moving, short term flows through our plant while it is under construction. As is our practice, we are reviewing our operating procedures with staff to learn more. We want to ensure that all protocols are followed and that new protocols are added as necessary.”
The chlorine contact chamber was in full operation on Tuesday (July 11) when a press conference was held at the plant, Tankersley said.
“The contractor began modifications to the existing chlorine contact chamber on Wednesday. In order to construct the planned improvements to the chlorine contact chamber, the contractor took half the chamber offline, leaving the other half available to handle daily flows. Modification of the offline chamber began Wednesday for a 10-day rehabilitation,” Tankersley said.
“The fast inflow of storm-related flow made it all the way through our treatment process to the chlorine contact chamber. The water received chlorination/disinfection before spilling over the sides of the chlorine contact tank in use.”
Wet weather flow started entering the SWWRF at about 6:30 p.m. The plant successfully treated and disposed of 1 million gallons of wet weather flow during a two-hour period (total two-hour flow was 3.7 million gallons).
Tankersley said that “50,000 gallons of treated water was spilled over the contact chamber walls. We then regained full control of the wet weather flows and successfully managed the remaining 2.75 million gallons. (5.5 million gallons of total flow over six hours).”
There was no discharge of any water from the plant property.
Work at the plant involves expansion of capacity to help prevent future discharges. A second project involves the ability to convert biolsolids to energy.
For information about St. Petersburg’s public works department, go to stpete.org.
File photos of ongoing work at the Southwest Water Reclamation Plant by Anne Lindberg, TB Reporter.
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