Constructed as part of a larger wastewater treatment plant expansion project, the Algonquin WWTP Intermediate Pumping Station lifts primary clarifier effluent and return activated sludge to the head of the 5-stage phosphorous and nitrogen removal process. The station is configured with three screw centrifugal horizontal dry pit pumps, each capable of pumping 10 MGD. The station is designed to ultimately house 6 pumps, bringing the ultimate pumping capacity to 50 MGD with one pump out of service.

Each pump is equipped with a dedicated force main and flow meter, properly sized for the full range of flow for the individual pump, resulting in more accurate flow information at lower flows than would be possible from a single large meter. In addition, the dedicated force main for each pump solves lower flow velocity issues while allowing higher flow rates at lower horsepower than combined force main systems. An additional advantage is that meters can be isolated and serviced one at a time while the other pumps remain in service.

The pumps, 75 hp Wemco Hidrostal screw centrifugals, were chosen for their overall efficiency and reliable operation.The pumps are equipped with VFD’s for flow paced operation.

The project was completed and placed into service in February 2008.


Scott Trotter, P.E.