When a hurricane makes landfall, the accompanying torrential downpour can easily overwhelm a wastewater treatment facility. The City of Largo has experienced downpours caused by hurricanes and wanted to guarantee its wastewater treatment operations would remain fully functional during storms without disrupting the community.

Largo’s upgraded facility has a new influent pump station, headworks facilities and a five-million-gallon equalization tank capable of holding the surge flows that come with wet weather events, even during a Category 4 hurricane.

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 location off-site. This ability to activate or deactivate Largo’s facility meant it could continue to treat wastewater in the facility while keeping waste in and water out.

Existing plant operations required that the influent pump station and headworks startups occur concurrently. The team worked closely with a supplier to place a temporary bypass pipe on standby and turn on this system early, should a storm approach.

A complex operational treatment plant can pose risks to the ongoing and necessary treatment of wastewater.  A plan to install two 30-inch-wide raw sewage pipes from the new headworks to the existing aeration basins, by jacking and boring directly underneath the facility, shows the type of foresight necessary. These pipes transfer screened and de-gritted wastewater to the plant and are critical to its successful operation. Exploratory drilling of potholes where the tunnels would be placed identified several critical power feeds that ran through the intended excavation zone in one of the most congested areas of the plant: an area that contains critical electrical house infrastructure, sewage piping, aeration and many other plant processes.

To avoid undermining the facility’s underground utilities and potentially harming the plant’s primary power source, the project team investigated alternative routing for the raw sewage pipes. We created a 3D model of the facility’s current underground power and pipelines to communicate a clear path for the pipes that eliminated the risk to crucial power feeds and made lines accessible for future maintenance.

The City of Largo now has a wastewater treatment plant prepared to handle hurricane-force waters at the flip of a switch. Citizens can thank the municipality for its forward thinking in fully upgrading their entire wastewater collection and treatment system. 

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