When big storms or hurricanes hit, thousands of homes and businesses lose vital power, communication and water and wastewater services. The loss of these services forces consumers to pay attention to the importance of public utility systems and the emergency backup systems that keep them operating after a disaster.
The traditional method to backup an electrical-driven sewage lift station is a diesel-driven generator. However, diesel-driven pumps are now replacing generators as an improved backup plan. This independent pump unit is a more effective solution to lift station problems such as sewage pump failures. The versatile diesel dry-prime pump also supplements the lift station when routine maintenance or emergency repairs are necessary.
These standby backup lift station pumps offer numerous benefits over standby generators. The pumps are fully automatic, independent, versatile and user-friendly. Pumps are less expensive than comparable diesel generators and-most important-they offer the added assurance that there will not be a spill from overflow if the main pump operation is interrupted.
The type of recommended pumps used as backups are self-priming, solids-handling with dry-priming systems and automatic start/stop capabilities. As with all machinery, the backup pump must be maintained. However, little maintenance is required other than to start them occasionally and check on the batteries. Additionally, solar battery chargers are an option to keep the batteries fully charged.
Independent diesel-driven pumps have evolved to provide the beneficiary features desired by cities and municipalities. They are offered with sound-attenuated canopies which can reduce sound pollution to meet EPA standards at 76-dBa or below at 23-ft. They are available in sizes 3-in to 18-in with flows to 11,000-gpm, heads to 430-ft and solids handling to 4.25-in. Automatic start/stop systems can be used with floats or transducers to measure the wet well sewage level. These pumps can also be outfitted with automatic monitoring and notification of their performance conditions.
It is important only to deal with nationally reputable pump companies with previous experience in backup lift station pumping. It is critical to estimate anticipated flows and determine the appropriate pump for a specific lift station. A company with previous experience is critical because this type of application is relatively new for many companies.
Case Study: Better Lift Station System Needed
Dewey Wilson, General Manager for Regional Utilities, decided he needed a better lift station system. "We needed a better emergency backup system as soon as possible," Wilson said. "And we needed it not just to continue to provide uninterrupted service to our customers, but to keep the pumping fluid from polluting the environment. In addition, we needed a way to perform periodic maintenance on our master lift stations. Permanent backups would allow us to do just that."
Wilson, who has worked for Regional Utilities for more than 17 years, began researching the possibility of permanent, hard-piped, diesel engine-driven pumps as emergency backups for the lift stations. He contacted one manufacturer hoping that he could secure pumps that would automatically start after a shutdown or failure at any of the company's master lift stations. Wilson knew that pumps could be rented in emergencies, but opted for a more permanent solution.
The pumps would have to prime fast enough to prevent lift station overflows and handle the estimated capacities for each of the lift stations. In addition, the automatic start system would have to be simple enough to remain idle for a long period, but reliable enough to guarantee starting the pumps.
The solution determined was to install fully automatic, diesel-driven pumps as emergency, standby backups.
The big test for this permanent backup system came in August and September of 2004. Several hurricanes blasted through Florida and the Panhandle area, and each took out local power. However, Regional Utilities' backup pumps kicked into gear and maintained the utility's service through each siege.
"They were life savers," according to Wilson. "All ten . . . pumps automatically started and kept sewage levels from rising high enough to escape the lift stations. I really cannot say enough good things about them." Regional Utilities also used four portable pumps at other lift stations.
In Summary
Today, stationary lift stations can be backed up by pumps instead of generators. The standalone pump not only offers added pumping power during stormy times, but is capable of pumping sewage during scheduled maintenance or emergency repairs. With the increased capabilities of automatic start, stop and speed control, these portable pumps offer more features than generators.
While most lift stations have electrical pumps as the main pump, there are often power outages. This is when the traditional diesel-driven generator provides power to the electrical pumps. However, what if it is not the power that goes out, but the pump itself? This is when the standby backup provides not only power during an outage, but also pumping capabilities. A sewage spill can occur if a generator is used rather than a diesel pump.
In conclusion, pumps have already been proven to be a cost-effective and efficient solution when conducting bypass projects. Now, utilities can use them as a permanent standby backup system.
Pumps & Systems, March 2008
