Preparedness is your best bet to winning a race against Mother Nature. The city of Largo, Florida, often in the path of hurricanes, needed to upgrade its wastewater reclamation facility with the capacity to handle intense and prolonged rain events at the flip of a switch.
Mechanical bar screens combined with biological odor
control remove foreign objects prior to wastewater
entering the process.
Sludge thickening process.
Grit and sand removal equipment.
PCL’s Water Infrastructure Group provided the city of Largo, as part of the Largo Influent Pump Station project, with a new headworks facility to process flows and prevent clogs, an order odor control system, and the ability to overcome heavy downpours and remain fully functional. The new-and-improved pump station has the increased capacity to handle up to 43 million gallons of wastewater per day—making it a formidable match for Mother Nature.
Mother Nature Comes Knocking
When hurricanes make landfall, the accompanying downpours can easily overwhelm wastewater treatment facilities, causing wastewater to be released into the surrounding neighborhoods or local waterways. Many municipalities in the Tampa Bay region experienced this during the summer of 2016 when they received excessive rainfall from Tropical Storm Colin and Hurricane Hermine.
Having experienced these tropical downpours, the City of Largo wanted to greatly reduce the possibility that its wastewater treatment operations would remain fully functional during storms without disrupting surrounding neighborhoods. To ensure the new pump station can handle major storms, PCL upgraded the facility and included a five-million-gallon equalization tank capable of holding surge flows that accompany wet-weather events. The new infrastructure was incorporated into the City’s supervisory control and data acquisition system, which allows the City to control the flow of water in and out of its facility from a safe, off-site location. This ability to activate or deactivate Largo’s pump station means it can continue to treat wastewater in the facility during periods of high water volumes, while keeping waste in and water out.
The Power of 3-D
One of the contract requirements was to install two 30-inch-wide raw-sewage pipes by jacking and boring directly underneath the facility, a narrow and congested area. These pipes are critical to a successful operation because they transfer wastewater, once it has been screened and cleared of fine sands, to the plant.
The project team prepared the site for excavation by drilling potholes in which the jacks would be placed. While preparing the site, they identified several critical power feeds that ran through the intended excavation. To avoid undermining the facility’s underground utilities and potentially harming the plant’s primary power source, the project team created a 3-D model of the facility’s current underground power and pipelines. The model showed a clear path for the raw-sewage pipes, and so the project team and the owner made the decision to relocate the
lines to a less congested area of the plant. Moving to this new excavation area eliminated the risk to plant operations and provided the facility with the means to access the lines for future maintenance.
The project leaves the City of Largo with a new influent pump station that can more reliably treat wastewater 24/7, 365 days a year, even during Mother Nature’s biggest wet-weather events.