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Water is life. We’ve fought over it, built cities around it, built lakes to supply it, walked fields with a tree branch trying to divine where to dig for it. Today, the biggest problems remain supply and quality. 

Norman gets a third or more of its drinking water from wells that tap the Garber-Wellington aquifer. That well water goes untreated into the mix with treated water from Lake Thunderbird and winds up in our homes and businesses. 

If Environmental Protection Agency guidelines change, however, Norman’s well water may be treated to remove contaminants in the future.

Chromium-6 is at the top of the list.

“Chromium is an odorless and tasteless metallic element,” according to the EPA.

The metal is found naturally in rocks, plants, soil and animals, and it’s in our water. While some chromium is beneficial, the EPA is “reviewing data from a 2008 long-term animal study by the Department of Health and Human Service’s National Toxicology Program, which suggested that chromium-6 may be a human carcinogen if ingested.”

For now, the parts per billion or maximum contaminant level (MCL) of chromium-6 allowed in drinking water remains unchanged, but Norman utility officials think the EPA might lower the allowable level in the future.

“We’re planning for it, we have a future budget item on the books,” Capital Projects Engineer Chris Mattingly said. “This pilot study will provide information for brand new technology and, in the future, may provide a new way to treat for chromium.”

That budget item is a place-holder rather than actual funding, but it recognizes that there may be a need for additional water treatment to deal with chromium-6 in the future. 

For years, the Norman Utilities Authority has researched treatment options for chromium and other metals, and now a grant from the Bureau of Reclamation is making a pilot study possible that could provide an economically viable means of removing chromium-6.

The Norman City Council recently approved a $334,254 contract with Carollo Engineers Inc. to install the biotttaTM pilot trailer at the Water Treatment Plant and to perform testing and analyses of removing the chromium-6 from the well water over a one-year period. Over half of that contract cost will be covered by a Bureau of Reclamation grant for $191,647.

The pilot project will treat well water from Well No. 5 using Carollo’s biotttaTM biological treatment unit, according to city staff reports.

Dr. David Sabatini with the University of Oklahoma, the Oklahoma Water Resources Board and the Oklahoma Department of Environmental Quality will each provide technical reviews of the study.

Mattingly said the technology belongs to Carollo, a firm that has had an ongoing relationship with the city on various projects.

“They used technology to do nitrate removal in California, and it worked,” Mattingly said. “It looked like it was also removing chromium-6.”

There’s also potential for this method to be cost-effective in removing arsenic and other metals.

“That’s exciting,” Norman Utilities Director Ken Komiske said. “That’s why you do these pilot studies, to see if this really works.”

Additionally, the Bureau of Reclamation plans to do a second pilot study with Norman this fall to look at two treatment techniques: ion exchange and RCF (reduction, coagulation, filtration) to remove chromium-6.

Ion exchange uses reversible chemical reactions to remove contaminants such as nitrate, fluoride, sulfate and arsenic, as well as others from water, according to the EPA. 

The RCF process uses ferrous iron to reduce chromium-6, according to the Water Research Foundation.

That BOR study will allow allow Norman to compare all three methods. In the case of the ion exchange and RCF study, Norman will provide staff time, but no monetary investment will be required.

“Everyone knows reverse osmosis works,” Mattingly said, “but it’s very expensive. These studies could reveal economical alternatives.”

Joy Hampton



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