Stay out of storm water.
After Milton, some Plant City residents reported sewer backflow that came up through their showers, sinks, and toilets. But this isn’t the only water hazard that is out there. Here are some things to know about water as peak hurricane season approaches.
Plant City’s sewer system is what is known as an open-channel system. Gravity moves wastewater downstream through a network of pipes, rather than being transported by a pump system. This is why sewer laterals and pipes always slope down.
Lift stations are placed at strategic points to elevate wastewater so gravity can keep it moving toward the treatment facility. To keep the lift stations running in a storm, the city has stationary generators at the larger lift stations. In addition, the city has a fleet of temporary generators they deploy at the rest of the lift stations before a storm to make sure the sewer system doesn’t back up and flood, and instead flows to the places it is supposed to.
Another way to route sewage is a pressurized system. With this option, the system is pressurized so that wastewater can be forced through the system whether the pipe goes down or up. These pressurized systems can spew wastewater up from drains and toilets in a home.
Unlike pressurized systems, gravity-based systems do not generate the force necessary to push wastewater backward through residential pipes. In Plant City, sewer mains are buried at least three feet deep and, in some places, are 20 feet under the ground. Most residential buildings are constructed at elevations above the manholes, and there are P-traps on all drain lines. Even if pipes fill up, all of these safeguards in a gravity system prevent sewer water from spewing from toilets or drains.
“While the likelihood of sewage discharging through toilets remains minimal under standard overload conditions, an exceptionally overwhelmed collection system may find alternate pathways for discharge,” Hye Kwag, Utilities Engineering Manager, said.
For sewage to backflow into a home during a hurricane, a more likely cause is breaks or cracks in the pipes on that property. Tree roots are a common culprit. Sometimes this will also happen with older pipes. Another possible cause could be if the cap on the cleanout has been removed or damaged. If a storm is so heavy that it raises the groundwater level over the pipe, the water can flow into the pipe, and this can pressurize sewage and push it back up to the house. Plumbers often offer sewer line assessment services to determine whether pipes need to be replaced. The best time to have this done is now, before impending hurricanes increase wait times for the service.
“Florida doesn’t have what we call in the industry, combined sewer systems,” Lynn Spivey, Director of the city’s Utilities Department, said. These systems are used sometimes in the northern U.S. They combine them both into one stream. “Our storm water does not enter our sewer collection system. It’s a whole separate system. For Plant City, our entire storm collection system ends up in a series of canals that go out to Itchepackesassa Creek, and eventually to the Hillsborough River. So, we don’t have combined systems in general.
Plant City’s stormwater system can handle a flow rate of five to six million gallons a day. During Milton, the flow rate peaked at 27 million gallons a day. Before the Milton flooding completely subsided, kids could be seen playing around in the stormwater runoff, running in it, and riding their bicycles through it. “I think people don’t understand just how dangerous stormwater is,” Spivey commented. “Storm water has everything under the sun in it; fecal matter from everything, from every animal out there, everything that is on the ground. People should know not to go into stormwater, not even to walk in it. It is going to enter any cut on your body. Stormwater is really, really dangerous. It is basically nature’s toilet.”
City government operations did everything they could to prepare before Milton hit. But of course, the city conducted a hurricane post-mortem. “Our responsibility is to deal with the infrastructure impacts and try to work to minimize any future impacts,” City Manager Bill McDaniel said.
