Dave Olson, Published December 27 2010
Moorhead H20 ‘best in glass’
Slapping an additional atom onto a typical oxygen molecule creates ozone, which the city of Moorhead uses as the primary disinfectant and treatment agent for its municipal water supply.
Troy Hall, water division manager for Moorhead Public Service, said Moorhead’s ozone-based treatment plant is a rarity in this part of the U.S. and one of the reasons Moorhead water has won “best in glass” status for two years running, based on judging by the Minnesota Section of the American Water Works Association.
Moorhead Public Service keeps its 2009 and 2010 state drinking water trophies at its treatment plant, near the intersection of Highways 10 and 75.
The plant opened in 1994, and the ozone process kicked in the following year.
Electrical discharges, including lightning strikes, are one way nature transforms regular oxygen into ozone.
Because it is highly reactive with other chemicals, ozone gas does not last very long.
The Moorhead water plant manufactures its own supply of ozone by using large metal chambers that create mini lightning storms.
Plant workers add ozone to the water after it has undergone softening to extract minerals.
The water is then filtered before being piped around the city.
The treatment process also involves a little fluoride and chlorine thrown in for good measure, with the fluoride aiding in the fight against tooth decay and chlorine serving as a secondary disinfectant.
It all makes for a complex mix that MPS workers take pride in getting right.
“We’ve got a lot of really smart operators with a lot of experience,” said Gena Dahl, an MPS chemist who prepares the water samples Moorhead takes to the American Water Works Association conventions held in Duluth.
Many factors determine how Moorhead’s water gets treated, according to Dahl.
“Everything from monitoring the weather, to when the college kids are in town; who’s taking showers and when. Just knowing all the conditions that go into it,” Dahl said.
The city treats about
4.3 million gallons of water a day, with much of that going down the drain early.
“Between 7 and 8 a.m. is probably our biggest demand time,” Hall said.
Red River water enters the system at a site near Elm Park in south Moorhead.
It takes about two hours for the water to make the three-mile journey to the treatment plant, where it is given its shot of ozone.
Besides disinfecting, ozone breaks down organic material in river water that might cause taste and odor, according to Hall.
He said that on a yearly basis, Moorhead takes about 85 percent of its water from the Red River and 15 percent from wells.
“During winter, we’re generally 100 percent river water,” he added.
After taking state honors in 2009 for having the best drinking water, Moorhead went on to the national competition but didn’t make it into the top five.
Winning the state competition again this year earned Moorhead another berth at the national competition, which will take place in June.
After one of the state competitions, Hall said a judge who helped select the top finishers took him aside.
“He said there was a definite difference in Moorhead water; they really noticed a difference,” Hall said.
How water samples are prepared for contest
Here is the official procedure Moorhead Public Service uses to prepare drinking water samples for state competition:
- Thoroughly clean an amber glass bottle. An amber bottle will minimize the effect of sunlight or room light, which could potentially alter the taste.
- Run finished water from one of the two reservoirs into the bottle for several hours to help remove any residual material that may be on the inside surface of the bottle.
- Once sample is collected, leave cap on bottle loose for several hours to allow any gases in sample to be released.
- Attach a label to “rib” other competing utilities.
- Cap bottle and transport to competition.
A recent sample bottle carried this line to taunt rivals: “We don’t make water, we make it drinkable.”
Readers can reach Forum reporter Dave Olson at (701) 241-5555