October 28, 2013 9:55:53 AM
Nathan Gregory - email@example.com
EDITOR'S NOTE: There are few infrastructure systems as critical to a community's health and prosperity as a city's water supply. Beginning with Sunday's look at the Columbus wastewater treatment facilities, The Dispatch continues an examination of three critical aspects of the water system with today's look at the city's water supply.
Mitchell Brown makes sure Columbus residents have clean water to drink.
He does this by overseeing the city's two water treatment and distribution plants and the equipment that processes raw water from 1,000 feet underground into something fit for consumption.
Columbus is one of several northeast Mississippi counties that benefit from the Eutaw-McShan aquifer, which means a low risk of any contamination as opposed to municipalities that rely on surface water plants. Columbus Light & Water general manager Todd Gale said the fact that the aquifer is so far underground means there is little to no threat.
Eight wells -- four in north Columbus and four more in south Columbus -- draw the raw water from the earth and pass it to each plant's aerators, which oxidize the liquid and remove hydrogen sulfide before moving the product to sedimentation basins known more commonly as clarifiers. These circular, open-air tanks are where chlorine is added to disinfect the water before lime is introduced to ensure the water has a pH measure of about 8. An electronically powered paddle wheel mixes the two agents with the water. In other words, Brown said, the lime neutralizes the water.
At this stage, the water coagulates, or turns temporarily into a semi-solid. What eventually becomes drinking water ascends through flumes to the top of the tanks before moving to eight filters, which also remove impurities. The rest settles at the bottom of the tanks.
One of the last stops is the clear well, where phosphate and fluoride are added, before the finished product is pumped to either a 2-million gallon storage tank at the south plant or one of two 750,000-gallon tanks at the north plant. The plants' service pumps can then send water through pipes to consumers at 1,500-3,000 gallons per minute, Brown said.
In case of a power outage, water treatment crews have a generator that powers a well and the computers that control all the equipment so supply is uninterrupted.
Another plant operator, Donald Freshour, said each day he takes water samples to make sure the balance stays at the appropriate level. He also creates the mixtures added to each area of the plant to clean the water.
"It's just like making the same cake over and over again," Freshour said. "You know what you want, you add the chemicals. Over the years, they've already figured it out. (The south) plant is different from the north plant because we're constantly getting on and off different wells. Sometimes we've been on as high as four wells. Even one well down there puts 2,000 gallons a minute out. We've got to adjust the chemicals because when you're running one well you've got a maximum amount coming out of it. But if you've got two wells running, they're pushing against each other, so you've got to back off."
■ Coming Tuesday: Drainage
Nathan Gregory covers city and county government for The Dispatch.