Within two years of purchasing twin glass-lined standpipes, the Old Town Water District found itself facing two very different yet related problems: The standpipes were showing signs of serious ice damage in winter, and poor water quality in summer months due to large changes in disinfectant residual levels in their tanks. Both problems related to poor hydraulics within the storage tanks. Thus, the water district turned to a single solution to fight both the hot and cold: a PAX submersible mixer.
“I studied all the methods—there are several—and we decided on this mixer that’s actively in there working because it creates a current, drives the water upward and circulates it within the tank,” said Frank Kearney Sr. “We were concerned that our tanks are 100 ft tall and, would this really work in something that’s 100 ft high? We put it in, and we started the first one in early winter—there was already some ice that had formed on the sides of the tank. Within a few days time, the ice was gone.” Energy efficiency and ease of operation also were attractive aspects of the mixers to the water district.“We were relieved to know that it only cost about $1 per day in electricity here in central Maine to run it,” Kearney said. “As far as annual operating costs, that was a relief to know that it wasn’t going to be a burden to keep running the thing. Another thing is simplicity. We didn’t want to have to alter our tanks to have a solution for this. I felt that we could do something simple that wouldn’t require welding or restructuring the inside of the tank or require us to change the way we produce our water.”After the first winter and climbing into the tank several times, the district was impressed and ordered another mixer in the summer of 2009. In the summer of 2010, the district installed a third one in a much bigger, welded steel tank about 50 years of age. Preventing ice in that one will preserve the coating inside. “It’s a painted tank, so this summer before I put the third mixer in, we contracted with a paint and renovation company and we sandblasted the inside of that and recoated it so it’s like brand-new. Especially with the mixer, it should be good for another 30 years,” Kearney said.As impressively as the mixer had solved the ice problem, it took care of the district’s summertime issues as well.“We climbed the tank with the mixer and opened that hatch, and it was a chlorine smell like you’d expect treated drinking water to have—a very clean smell,” Kearney said.