Case Study: Rathbun Regional Water Association

When the grid goes down, how does a water company keep 36 water towers full?

For Rathbun Regional Water Association (RRWA), a provider of water to southeast Iowa, Rehlko standby power kicks in.

“Our two Rehlko backup generators—one at the caisson pump building that brings in our raw water and the other at our treatment plant—take over so we can keep processing water,” says Rod Witt, RRWA in Centerville, Iowa. “And the Rehlko units get the job done; no worries there. But without power throughout our distribution area, we’re facing a bigger challenge: we have 36 water towers that need pumping power to replenish levels.”

Rathbun’s 36 towers are spread over 140 miles of rural countryside and connected by nearly 6,500 miles of pipeline. Once water is elevated into a tower, gravity delivers it to residences, farms, factories, and schools throughout the system.

“When power is lost, the water from a tower keeps flowing,” says Witt, “but a clock starts ticking on how soon each tower will run out. Some towers last a day or longer; others need to be replenished in just a few hours.”

When outages occur, an emergency plan is initiated in the high-tech Rathbun control room.

“We essentially have 36 different countdown clocks, one for each water tower, based on water levels and projected usage. It’s kind of like an action picture that plays out in slow motion.”

The challenge becomes even greater when outages extend across rural territory. During the ice storm of 2007, Iowa was coated with up to two inches of ice and hit with wind gusts exceeding 50 miles per hour. Several thousand power poles snapped, and even 345-kV transmission lines were downed. Power wasn’t restored in some rural areas for up to a week.

To maintain tower levels during extended outages, Rathbun relies on mobile generators from Rehlko Power Systems. Each of four mobile generators is strategically moved among 39 pump stations throughout the distribution area. Units run for several hours to top off a water tower before moving on to the next station.

Bryan Buckingham of Electrical Engineering & Equipment (3E), the Des Moines, Iowa distributor providing sales and service support to Rathbun, explains that 3E teamed up with Rehlko in 1999 to develop custom mobile generators built to Rathbun specifications.

Back in 1999, Rathbun already had a 1250 kW Rehlko standby generator that had been struck by lightning. One of 3E’s technicians rewired the entire unit, and it continues operating today.

Since then, Rathbun has added 1000 kW and 1500 kW Rehlko generators at its new water treatment plant.

“When the engineers wrote the spec for backup power for the new treatment plant, they included ‘Rehlko or equivalent’ backup power,” says Witt. “We just said there really is no equivalent — we’re very comfortable with Rehlko and want to stick with them.”

“With the drought in the summer of 2012, we peaked at pumping 10.5 million gallons of water in a single day,” adds Witt. “That’s 2.5 million more than the capacity in our plant design.”

Through fully integrated system design and dependable mobile deployment capabilities, Rehlko backup power enables RRWA to:

• Maintain water processing during grid outages

• Sustain operations during prolonged weather emergencies

• Deliver uninterrupted water service to residences, farms, factories, and schools