Apr 20, 2011

Picture-Perfect Mixing

Whoever said tanks were just for holding water? In Yuma, Ariz., the city’s three potable water tanks are works of art. Featuring colorful murals of the local landscape, the 50-ft-high, 100-ft-wide tanks are a drive-by gallery on display to anyone on Interstate 8. More important, of course, is the quality of the water inside the tanks. Thanks to SolarBee mixers , Yuma’s drinking water is now picture-perfect too.

It has not always been that way, according to Bill Barbieri, chief plant officer for Yuma’s water department. The city’s tanks—each with a maximum storage capacity of 3 million gal—had problems with short-circuiting and stratification. The result of inadequate mixing, these problems led to uneven water age and inconsistent chlorine residuals in the tanks.

“We never had a problem meeting compliance regulations, nor were taste or odor an issue,” Barbieri said. “But we were creeping up on our levels of THMs (trihalomethanes, a disinfection byproduct) and we knew the tanks had stratified. Because of short-circuiting, we didn’t have full use of the capacity of the tank.”

At first, city officials considered installing diverters on the inlets. Instead of directing water straight into the tank, a 45-degree elbow would divert it higher up into the tank. However, upon further study, officials concluded that such a solution would be cost-prohibitive and ineffective.

Barbieri learned of SolarBee mixers while visiting Las Vegas for a conference. SolarBee mixers are installed in the water system there. After further study, the city of Yuma installed one SolarBee SB2500v12 unit in each of the three tanks.

Energy-Efficient Solar Technology

The solar-powered, floating SolarBee mixers in Yuma’s water tanks operate day and night with a permanent magnet, low-voltage motor and an onboard battery system for continuous, energy-efficient water quality improvement. The unique SolarBee flow pattern ensures consistent dispersion of disinfectant throughout the tank, including constant replacement at the walls, in the bottom 3 ft of the tank and on the floor, where bacterial growth would otherwise flourish due to lack of disinfectant. By actively mixing Yuma’s potable water storage tanks, SolarBee mixers help ensure uniform distribution of disinfectant, eliminate thermal stratification and prevent stagnation and short-circuiting. In addition, well-mixed tanks eliminate the need for energy–intensive deep cycling or tank flushing.

“We liked the greener approach of solar-powered mixing,” Barbieri said. “The tanks are in an isolated area with a limited amount of electrical power. We also liked the fact that the SolarBee mixers are capable of stand-alone operation.” An added plus was SolarBee’s BeeKeeper service program, which provides onsite maintenance, power system upgrades and repair of damaged equipment, even if the damage is caused by an act of nature.

Since the SolarBee mixers were installed, the city’s comprehensive monitoring has confirmed that water temperatures are uniform throughout each tank, stratification issues have been resolved and there is no longer any short-circuiting. The city uses less chlorine for disinfection and chlorine residuals are now more consistent. Furthermore, average concentrations of THMs dropped from 71 µg/L to 46 µg/L in the first two years since the SolarBee mixers began circulating tank water.

Yuma water officials constantly look for ways to deliver the highest quality water to residents. With SolarBee mixers, they are assured that the water supply is not only safe and tasty but also sustainable.

Medora Corp.


3225 Highway 22

Dickinson, ND 58601

United States

Phone: 866.437.8076

Fax: 701.225.0002


[email protected]