Best practices: preventing overflows
Floating waste on the surface can potentially lead to fouling of the level sensors. This causes the automated system to malfunction, resulting in overflows. So it is important during inspections to routinely clean sensors and implement a system to collect floating matter if there an abundance.
In our community, we implemented an integrated solids separation system, which has enabled us to reduce overflows due to pump clogging to almost zero. In fact, coming from the network is filtered through a drum screen that only allows the liquid part to pass through the pump casing to fill the tank. When triggered, "clear" water from the storage tank flows through the pump and cleans the screen, taking with it any unwanted waste.
We have also set up a separate screen to protect the network from wipes. This one was installed downstream of a long pipe run without connections to allow feces to liquefy and therefore only remove the wipes.
Automated measures are also useful: reversing the direction of rotation of the pumps to force unclogging. You can also program automatic pump start levels modifications to prevent FOG build-up in the lift station and force starts outside normal parameters for pumps that are triggered infrequently.
Finally, it is important to choose the right type of impeller for wastewater pumps: free-flow, vortex or grinder pumps
Optimizing the collection network upstream of a stormwater weir or à lift station is also a good strategy to limit peak flows and therefore overflows.A series of control valves on the network can also provide low-cost and efficient dynamic management.
Daily monitoring of data from lift stations and stormwater overflows is also essential to limit unwanted discharges. If you have not already done so, I suggest you equip your remote management system so it can monitor minimum volume, runtime /spill time, and pump starts. That way you can respond quickly to any abnormal situations and maybe even anticipate pump failures.
Feel free to take a look at the dashboards that we have built with operators to facilitate precisely this monitoring of lift station and overflows and be alerted in case of problems on pumps or spills occurring outside of wet weather conditions.