Water Tank Work May Cause Issues

by Gregg Jones, originally posted on October 29, 2016


 Union residents shouldn’t be concerned of fluctuations in water pressure, or possible chlorine tastes and odors, in the city drinking water.

That’s according to City Engineer Jonathan Zimmermann who said upgrades to city water tanks may cause the pressure changes and chlorine taste. Only those in the western portions of the city will be affected.

“We want people to be aware that any fluctuation is in association with work we are doing,” he said.

The city contracted with Maguire Iron, Inc., Sioux Falls, S.D., to make major changes to the drinking water systems, which include new mixing mechanisms at three storage tanks.

Zimmermann added that the city will use chlorine to disinfect the tanks after work is complete.

“They are cutting holes in the side of tanks and people will be walking in and out,” said Zimmermann. “Before we put the tanks back into service they will be disinfected.

“Once the tanks fill back up, there may be residue of chlorine,” he added. “It will be temporary.”

The work is expected to take 45-60 days. The end result will be higher quality drinking water, Zimmermann said.

Water tank upgrades are necessary because the city was cited by the state after there were five water samples collected within the past year that contained coliform. The bacteria is not dangerous for consumption, but is a sign that there could be contamination.

The number of positive tests prompted a state-mandated drinking water study.

The mixing will move the stagnant water in the three city tanks on the west side of Union. Two of the tanks hold 1 million gallons of drinking water each.

Zimmermann said there is one inlet/outlet for the water in the water tanks, so the water does not move around the tank — that means warm water that has been in the tank longer stays at the top of the tank, while cooler water sits at the bottom of the tank. That is called thermal stratification.

The mixing of the water should prevent coliform from forming.

The eastern areas of Union are now chlorinated. The drinking water supplied to homes and businesses east of Highway 47 south is chlorinated, but the other areas of town are not.

The city is not required to chlorinate any drinking water now.

If there are more positive tests for coliform, the city will be required to chlorinate.

Zimmermann said if chlorination is required, the mixing system will be necessary, so there would be no additional tank construction costs.

Last year the city of Washington was mandated to chlorinate its water system after boil orders were issued when E. coli was found in the water system.

According to the Missouri Department of Health and Senior Services, “Coliforms are a group of bacteria found in the intestines of humans and other animals. Coliforms also occur naturally in the soil, on vegetation and in surface waters (lakes and streams). Most members of the coliform group do not cause disease.

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