City Saves Money with a Double-Duty Standby Generator Set from Cummins
|Challenge:||A substantial redevelopment project in the town of Wayzata, Minnesota was going to bring hundreds of new apartments, additional office space and a small hotel. All of that required an expanded wastewater system with larger lift stations.
One of the larger lift stations would handle wastewater for about half the town. Reliable standby power to run the station in the event of a grid power outage was essential because without power, wastewater would start backing up into homes in 20 minutes.
|Solution:||One 150kW gas generator set and two separate automatic transfer switches; a 400-amp OTPC transfer switch to serve the lift station and a 125- amp OTPC switch to serve The Muni. A PowerCommand® 2100 digital control for monitoring, metering, voltage regulation, digital governing and generator set control functions for the entire system.|
|Result:||The city has had to use the standby power system only once, when utility power was lost for four hours. The Cummins system performed exactly as desired: the critical lift station continued to operate, and The Muni was able to take care of existing customers during the outage.|
Wayzata: a growing village
The village of Wayzata (pronounced Why-ZETT-ah) enjoys a picturesque location on the northeastern shore of beautiful Lake Minnetonka, west of Minneapolis. Like most towns it has a sewer system with lift stations to carry wastewater to treatment facilities. Unlike most towns, it also has a municipally owned restaurant and liquor store, known affectionately to the locals as The Muni, but officially known as the Wayzata Bar & Grill and Wayzata Wine & Spirits. These city entities share an innovative solution for standby power.
The city redevelopment project required bigger wastewater lift stations. A substantial redevelopment project in the town was going to bring hundreds of new apartments, additional office space and a small hotel. All of that required an expanded wastewater system with larger lift stations.
Reliable standby power was essential to run the station in the event of a grid power outage
One of the larger lift stations would handle wastewater for about half the town. Reliable standby power to run the station in the event of a grid power outage was essential because without power, wastewater would start backing up into homes in 20 minutes. The city of Wayzata does have a number of portable generators that can be used to power lift stations. But having a permanent emergency generator at this larger lift station would save precious time and provide peace of mind.
Partnering with Cummins again
Having several systems from Cummins in place already, the city wanted to stay with Cummins for several reasons. There would be just one company to call for service. Continuing with the same supplier would make it easier for city maintenance staff to perform routine maintenance and troubleshooting tasks. Systems from the same company have similar designs and often use the same replacement parts, even if they are different models or sizes. And the city was happy with its relationship with Cummins.
An innovative use for extra generator capacity
The city staff calculated that the new lift station would need 125 kW of standby power to take over in the event of a utility power outage. In discussions with Cummins Sales and Service, the local distributor, it was determined that a 150kW model would be the closest-size generator to ensure adequate handling of the lift station load.
Then, inventive thinking on the part of city staff led to the realization that the extra 25 kW of capacity could be put to good use providing standby power for the coolers and cash registers at the city's restaurant and wine shop, since The Muni was located close to the site of the new lift station. One generator set could then serve two different city functions at a lower total cost of ownership. Doug Abrahamson, a sales engineer with Cummins Sales and Service, worked with city engineering staff to develop the detailed 60-page design specifications for the novel double-duty backup system.
A smooth installation
The model GGLB generator set and two separate automatic transfer switches were installed in December 2010 without any problems. The generator runs on natural gas (it can also run on propane). A 400-amp OTPC transfer switch serves the lift station and a 125- amp OTPC switch serves The Muni. A PowerCommand® 2100 digital control handles monitoring, metering, voltage regulation, digital governing and generator set control functions for the entire system.
Saving money upfront and later
The innovative solution saved money on the installation, since only one generator set had to be purchased and installed. Fewer replacement parts and less ongoing maintenance cost also reduce total costs.
"All the profits from The Muni go directly to support city services. So it's important for us to keep expenses down. Using the same generator system for both the lift station and The Muni is a good example of how we can be smart with needed expenditures and still get the emergency protection we need." Mike Kelly, City Engineer for Wayzata.
For more information about standby power systems for municipal water systems and other mission-critical applications, contact your nearest Cummins Power Generation distributor or visit www.power.cummins.com.