Ross Street Station, the main lift station located in the town of Swan River, MB, was constructed in 1975, and by 2012 parts for its original pumps could no longer be easily and readily obtained. Pump components that failed had to be manufactured, which was costly and made for long lead times. During the 2012 Manitoba Summer Games, Swan River received a monumental rainstorm that dumped over 76 mm (approximately 3 in.) of water on the area. The town soon discovered that a motor on the dry side of Ross Street Station had shorted out due to excessive moisture.
Swan River quickly declared a state of emergency and discharged wastewater directly into the river to prevent sewage backup into area homes. With the quick response of the town’s public utilities, the facility was able to get the issue under control and start working on solving the electrical issues in the dry pit.
Solution
After speaking with their consulting engineer—Associated Engineering—and Xylem, the town selected three Xylem Flygt horizontal dry-pit flood-proof NZ-3171 submersible pumps to replace the old equipment. These medium-capacity 600-VDC, 30-hp pumps, include self-cleaning N-impellers.
A wide range of spare parts is now kept on site for speedy replacement if necessary. In addition, other spares can be quickly ordered from Flygt’s North America central distribution center.
The old pumps created space issues because they were much larger than the NZ-3171 pumps, making service in tight quarters a dangerous situation. This is no longer the case with the smaller and sleeker Flygt dry-pit flood-proof pumps, which can now be easily and safely maintained.
Original voltage to the pump station was 600 VDC. However, since the older pumps had 230-VDC, three-phase motors, a transformer was required to set the voltage down. Replacement with the Flygt NZ-3171 pumps enabled the town to eliminate the need for a transformer.
During installation of new piping and pumps at Ross Street Station, a bypass system using an external engine-driven pump moved wastewater from the approach manhole to the force main. The newly upgraded Flygt diesel backup bypass system now allows the station to be shut down without putting the town at risk of wastewater backup and provides the town with 100% redundancy. Also, in the future the station can be bypassed during maintenance, ensuring worker safety.
Result
Installation of the three Flygt horizontally mounted dry-pit flood-proof NZ-3171 submersible clog-free pumps immediately offered a 25% boost in efficiency over their venerable predecessors.
Now with completely upgraded mechanical and electrical systems along with the new Flygt pumps, Ross Street Station has a capacity of 85 L/second running a single pump, 106 L/second running two pumps in parallel and 113 L/second with three pumps running.
