Gravity Sewer System
Gravity Sewer Systems are a conduit, utilizing the energy, resulting from a difference in elevation (Gravity) to remove unwanted water.
In ideal environments sewer systems are completely gravity fed. Meaning the pipes slope downward from the source, from your toilets and sinks to the waste treatment plants. Without the inconvenience of a pep tank and those components in the yard to deal with.

Lift Station in Gravity System Lifts Sewage back up and out into the system
Waste water has a lot of solids in it and so it’s hard to pump. Lift stations are used to bring the waste in on a lower end of the lift station. It is than lifted up, waste and all, releasing it into a vertical pipe at the higher level so the gravity flow takes over and drives the sewage out and down the pipes. The pipes tend to get bigger as they travel through the system as they connect and make their way to the waste treatment plants, Palm Coast has 2. Pipes leave homes at 6 to 12 inches in diameter and ends up 3 to 5 feet in diameter pipes and this happens throughout the system. These pipes run alongside the roadways and the lift stations and pumphouses are placed away from the city’s population.

pipes from 6 to 8 inches to 3 to 5 feet in diameter pipes
Pep Tanks and Gravity systems are very different. Both engineered for similar purposes but work on different levels of technology. Tanks are not used in the gravity systems and are maintained by city utility workers, with little to no effort from consumers. Gravity systems are not directly affected by power outages and because there are no tanks and pumps involved it lowers the malfunction possibilities to almost none.
If you want to learn more about these systems you can visit the City of Palm Coast website https://www.palmcoastgov.com/customer-service/peptankinfo