By Starrla Cray
LESTER PRAIRIE, MN What does Lester Prairie have that’s big, red, and weighs 30,000 pounds?
(And, no, it’s not Santa Claus.)
“It’s actually a three-in-one filter unit,” said project engineer Brian Gulden of Bolton & Menk.
The massive tank, which was installed in Lester Prairie’s partially completed water treatment facility Dec. 19, will be a key piece of the new system.
“This is the biggest round one we’ve ever built,” said Alan Hecksel of Hecksel Machine in Watertown. “We’ve built quite a few of these, and they’re all different sizes.”
Typically, large tanks are assembled on site, but because Lester Prairie is near Watertown, it was transported via semi.
One component of the roughly 20-foot tall tank is an aerator that sticks out of the top of the treatment plant building. It is used to oxygenate water before it goes into the second section, a detention tank.
“The water stays there for about a half hour,” Gulden said. “It allows time for the oxidation to happen.”
The third part of the unit is the filter itself, which includes four filter cells with materials to remove iron and manganese particles.
“Out the bottom, the water is pumped to towers, where chlorine and fluoride are added,” Gulden said.
Chlorine, which acts as a disinfectant, and fluoride, used for dental health, are both mandated by government regulations.
Orthophosphate (a corrosion inhibitor) is also added.
Summer of 2012
The system should be completed by June 2012, according to Gulden.
“Everything is on schedule,” he said. “The exterior is pretty well done.”
Inside the building, the first coat of paint has been applied, and the doors have been installed.
Now that the tank is in, the roof can be completed, as well as plumbing/electrical work.
When the new system is running, iron and manganese will be removed from Lester Prairie’s drinking water.
Although the hardness might be slightly reduced, home water softeners will still be useful, according to Gulden.
“Most of the hardness comes from calcium and magnesium,” he said.
Although iron and manganese are not a health risk, the Environmental Protection Agency recommends removal for aesthetic reasons.
High iron levels tend to produce rusty-colored water, sediment, metallic taste, and reddish or orange staining, according to the EPA website. Similarly, manganese can cause black to brown colored water, black staining, and a bitter metallic taste.
Currently, Lester Prairie’s iron and manganese levels are above preferred aesthetic standards.
The new water filtration system will be hooked up to the two main wells in town. A third well, which would only be used in emergencies, is not connected to the treatment facility.
The total cost of the project, including the 34-by-63-foot building, is $1,284,000.
The plant is rated for 350 gallons per minute, or 420,000 gallons per day, with 20 hours of run time per day.
In Lester Prairie, the average water usage during the winter is about 100,000 gallons per day. In the summer, average daily usage is about 175,000 gallons.
“Therefore, the plant offers sufficient capacity for future development and should serve the city’s water needs for the next 20 years,” Gulden said.