Gorman-Rupp self-cleaning sump for wastewater

Developed by Hydro-Plus in conjunction with Gorman-Rupp, the self-cleaning sump addresses many of the issues confronting owners of sewage pump station assets, such as high capital costs, high energy consumption and the cost of intervention for the likes of sediment, solids or fat build-up or for removing chokes from pumps.

With the self-cleaning sump, the conventional 2–3 m diameter cylindrical wet well is replaced by an inclined collector pipe from which self-priming pump suction lines access the wastewater. Nothing electrical or mechanical is in the sump. The system is used in conjunction with VFD-controlled pumps and an air bubbler liquid level control system to reduce energy consumption over the conventional DOL or soft-starting pump systems.

The philosophy behind the system is to keep solids in suspension and moving, and to take all issues associated with operator intervention to the surface where it is easier and safer for operators to address. Keeping the solid matter in suspension and removing it quickly does not allow time for fibres and rags to ball and mat together or allow sediment or fat to build up. This should reduce the incidence of pump blockage caused by balling rags and the need for ‘vac truck’ intervention.

Because pumps are mounted on the surface, there is no need for operators to open wet well lids or employ lifting devices. This makes any sort of intervention easier and safer for operators. Blockage removal, clearance adjustments, oil inspection or changes, valve greasing or exercising can all be done safely by one operator working out of a standard vehicle.

The civil construction costs are said to be much lower using the system because of the HDPE collector pipe (cheaper than a full concrete wet well/valve vault combination) and the smaller excavation footprint.