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1.21.03 Change is coming down the pipe today Slightly different drinking water will begin flowing through the pipes in the Omaha metropolitan area today. And while some Omahans may notice a difference in taste, they won't be seeing any difference in their wallet. The Metropolitan Utilities District has chosen -- by far -- the most affordable option available. Installing the equipment to add chloramine, which is a combination of chlorine and ammonia, cost M.U.D. $3.7 million. Other choices for treating the water ranged in cost from $20 million to $125 million and surely would have meant a rate increase, said Tom Wurtz, M.U.D.'s general manager. "There are number of good treatment options," Wurtz said. "There's Cadillacs and Chevrolets and Pontiacs." The chloramine option, Wurtz said, not only is the most affordable, but it also positions M.U.D. for tougher water standards down the road. M.U.D. is adding chloramine to the water to meet stricter federal standards that limit the number of byproducts that can result from the disinfection process. Some disinfection byproducts are suspected of causing cancer, so the Environmental Protection Agency has instituted tighter limits. Chloramine will create about half as much of the specific compound that concerns EPA. About 20 percent of U.S. water utilities use chloramine. Many of the rest use the double-chlorine method that M.U.D. has been using. Under this method, chlorine is used initially to disinfect water and then, because chlorine evaporates so easily, another dose is added as the water moves through the lines. The ammonia in the chloramine stabilizes the first dose of chlorine so it doesn't evaporate. Other methods used by some cities include ultraviolet light, ozone, membrane filtration or an activated carbon filtration process. Those processes would have been about five to 35 times more expensive for M.U.D. to install, according to M.U.D.. Each of these options also would cost about five to 75 times more a year to operate, according to M.U.D.. M.U.D. expects to be spending about $200,000 a year on chloramine. Other processes would cost anywhere from $1 million to $15 million to run. The reason for the difference in cost, in part, is in the complexity of the equipment. Adding chloramine essentially means squirting one more chemical into a modified treatment basin as the water is disinfected. Membrane filtration, ozone and granular activated carbon filters require much more costly equipment -- and the physical space for it. "Chloramine appears to be best for us," Wurtz said. "If we thought there was a better method out there that was a little more expensive, we would have done it." The primary reason M.U.D. is making the change is something called trihalomethanes, commonly referred to as THMs. THMs are born in the water treatment process. They form when chlorine comes into contact with organic matter in the water. THMs are suspected of causing cancer and have been linked to birth defects, although the evidence on the latter is much more inconclusive. Previously the EPA had permitted up to 100 parts THM per billion parts of water. But because of concerns about cancer, that standard recently was lowered to an average of 80 parts per billion and soon will be lowered substantially again. Under its old system, M.U.D. had been averaging about 74 parts per billion. Under the new system, it expects its THM levels to be about 40 parts per billion, said Joel Christensen, manager of water operations. That means M.U.D. will be in good shape when even tougher standards come out. Not all utilities are having to make changes in their treatment methods. The need to change largely is being driven by the source a utility uses for its water. Because water from rivers and lakes is dirtier than water from an aquifer, it contains more of the ingredients that are likely to bond with chlorine and form THMs. Thus, many of the cities contemplating chloramine or already using it are those that tap rivers and lakes for their water. Council Bluffs, Sioux Falls, S.D., Kansas City, Mo., and St. Louis -- all along rivers -- already use it. Nationally, health officials are continuing to study water treatment methods. As more information comes to light, more regulations may be issued that affect treatment methods. |
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