Switching supplies

Sunday, March 18, 2007
Two solid contact units at the water treatment plant on Cape Rock Drive reveal differences in the city drinking water. The left tank clarifies well water, and the right tank clarifies river water. In a year the city will switch to only using well water. (Kit Doyle)

In Cape Girardeau, the Mississippi River may turn a thousand tales, but beginning sometime next year it will no longer flow into faucets.

A proposed project now out for bid calls for the construction of well fields in the Black Land Bottoms in the southern part of the city. The wells will tap into aquifers in the area and make Cape Girardeau completely reliant on wells for its water source. Today, about half the city's water comes from the river, which water experts say is both dirtier and less reliable in quality than well water.

The four wells will come at a cost of over $3 million. Each will have the capability of pumping 1,600 gallons per minute for a total of about 10 million gallons per day. The project will also require five miles of piping to connect it to Water Plant No. 1 on Cape Rock Drive.

If all goes according to plan, water will begin reaching the plant in about a year. Plant operators say the transition can't happen soon enough.

"I'm going to sleep a lot better at night" when it does happen, said Kevin Priester, a manager with Alliance Water Resources, which operates the city's Water Division of Public Works.

Well water must be filtered of elements such as magnesium and iron, seen in the silty lower tank section. (Kit Doyle)

'They would just kill for that'

Priester said the current situation is not perfect, but it does work.

"We're very lucky. Most of the country thinks we've got it good. People around here kind of turn their nose up at the river, but believe me, if they had this river in L.A. or Phoenix, they would just kill for that." he said.

But the area is even luckier, he said, because of a massive reserve of water around the Buzzi Unicem plant along South Sprigg Street.

The swath of land leading west from the river lies along what historically was the Mississippi River bed. Since the last ice age, the river has been meandering gradually eastward at that spot. Geologists say it left behind an abundance of sand and gravel that now serves as a natural filter for the still-flowing underground water table.

River water, which changes dramatically depending on turbidity and river levels, will only be used as a reserve water source by the city in the future. (Kit Doyle)

"This is Mother Nature's filtration device. What you're doing is letting Mother Nature filter away the heavy particulate matter and taking the end result," said Dr. Christine Aide of Southeast Missouri State University's Department of Physics and Geoscience.

Aide said that is a cost-efficient filtration method that many riverside cities nationwide are taking advantage of.

Priester said the end product under the new system will be virtually identical to the tap water people are accustomed to. It will have the same color, same pH and same hardness. What will change, though, is how the plant treats the water.

"To me the biggest benefit by far is just the consistency of operation," Priester said.

River water, he said, is anything but consistent. It can contain heavy mud and algae blooms, chemicals and other materials that were dumped upstream and can vary widely in temperature.

"When you have river water, you always have the chance of having some unknowns get in there. A well is protected. It uses the natural filtration of the soil, and you always know what you're pulling. With a river there could be a spill upstream of a contaminant and you might need to shut that down," said city engineer Jay Stencel.

Even without the unknowns, river water requires intensive chemical treatment to become usable. A quick look at the pretreatment well water alongside river water at the Cape Rock plant offers a stark visual contrast.

"A visual check is not the best measure of water quality, but look -- it just has that aquamarine color. It looks like the Caribbean," said Priester, pointing to water pulled from wells near the plant.

River water, on the other hand, bubbles up into a brown, foamy sludge.

"It just has that appearance of a darker, greener water," he said. "I would say conservatively we will save a minimum of $50,000 per year in chemicals."

And they'll also be saving effort. Today, plant technicians regularly check monitors upstream to see if the river is contaminated. They also use computer testing devices to check incoming water. If turbidity, pH or any of a host of other factors change, then technicians must immediately change the treatment process.

For instance, highly turbid water requires a longer chlorine treatment to kill any organic elements. But the chlorination process has its own byproduct, called trihalomethane, that must be removed through another treatment.

Trihalomethane levels from treated river water can be as high as 80 parts per billion, which is the legal limit in Missouri. Trihalomethane levels from well water are less than two parts per billion. High trihalomethane levels have been linked to breast cancer in women and low sperm counts in men.

"Right now with a lot of the river water we have to postpone chlorination until we remove enough of the organics on the front end," said Priester of the regular maneuvers his team must do to keep low trihalomethane levels in water.

With well water much of those treatment maneuvers will be unnecessary. The plant will still chlorinate its water to meet federal and state regulations, but the treatment will not need to be as intensive and will always be the same.

That will leave some free time for plant technicians.

"I've been joking with them that I'm going to have to get them all paint brushes to keep them busy," Priester said.

The main treatment required of well water is a "lime bath" to soften it by decreasing its salt and calcium content.

River water also must be heated or cooled at the plant to a reasonable temperature because the Mississippi River ranges in temperature from just above freezing to 80 degrees.

Well water, on the other hand, is about 58 degrees year-round, perfect for drinking.

"Nobody likes to drink warm water. It's like warm beer. It just doesn't taste as good," Priester said.

The capacity of the water treatment plant is now 10.3 million gallons per day. That is significantly higher than the average daily output of about 6.5 million gallons.

But both Priester and Stencel are optimistic the new wells will increase the plant's capacity. Maybe not immediately, they say, but eventually.

"The plant will actually have a true capacity of 10 million gallons per day. Right now even though it's rated for that, it can't do it because it's dealing with two trains of water, one from wells and the other from the river. What we're giving the plant now is ideal conditions," Stencel said.

And Priester believes the surplus capacity could make Cape Girardeau more economically attractive.

"Ethanol plants and water-intensive industries are becoming attracted to this area. Most of the western states are putting conservation orders on everybody, and there's all kinds of lawsuits. We don't have any of that here, and that's good for industry," he said.

The well fields will be paid for with remaining money from the 1996 Water Sales Tax and bond initiative.

tgreaney@semissourian.com

335-6611, extension 24

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