Back to the Mar-Apr 2020 issue

New Treatment Plant Ensures Water Quality

City of Excellence Award

By Andrew Tellijohn

When the City of St. Anthony Village received notice from the Minnesota Department of Health in June 2015 that one of its wells was contaminated with a chemical that can cause cancer, city staff took immediate action.

Two of its three wells were testing below levels of concern and the entirety of its drinking water supply never reached toxic levels, so the city could have taken its time and pondered its options without notifying its residents of the problem in the well.

But the discovery coincided with national news reports about the water quality failures in Flint, Michigan. St. Anthony Village officials decided right away they were determined to solve the drinking water issues and avoid the potential public relations nightmare facing Flint.

So, the city immediately closed down the contaminated well, instituted testing of its water supply above and beyond those required by the state, created a communication plan for notifying residents of its progress, and began making plans for a long-term fix.

“First and foremost, we wanted to make sure we had the public’s trust in our ability to provide safe and reliable drinking water,” says City Manager Mark Casey. “That was important to the Council as a value.”

Ultimately, the city built the state’s first advanced oxidation water treatment plant. The project was the winner of a League of Minnesota Cities 2019 City of Excellence Award.

Learning about the contaminant

The chemical in question was 1,4-dioxane, a clear liquid used as a solvent in the manufacturing of other chemicals and as a laboratory reagent. Deemed an emerging contaminant, it can be released into the air, water, and soil.

Photo of a tour group at the water treatment plant
Erin Heydinger, project engineer, takes local children on a tour of St. Anthony Village’s new advanced oxidation water treatment plant.

The grounds of the Twin Cities Army Ammunition Plant in nearby Arden Hills were found to be polluted in the late 1980s. Because of that, St. Anthony Village upgraded its water treatment facilities at that time to begin treating other chemicals that were discovered in the aquifer that supplies the city’s wells.

As the technology available for discovering and measuring various chemicals improved, St. Anthony Village staff learned that the new chemical — 1,4-dioxane — was also coming from the Army Ammunition Plant.

Neighboring New Brighton had found out its water supply was tainted with the chemical, but that city had the option of closing down the affected well. Casey says that wasn’t a feasible, long-term option in St. Anthony Village.

Seeking solutions and communicating

When notified by the Department of Health, the city engaged on multiple fronts. First, it contacted the U.S. Army to discuss the situation and its role in helping clean up the water supply.

When the City of St. Anthony Village received notice from the Minnesota Department of Health in June 2015 that one of its wells was contaminated with a chemical that can cause cancer, city staff took immediate action.

Photo of St. Anthony Village’s water treatment plant.
St. Anthony Village’s new advanced oxidation water treatment plant.

Two of its three wells were testing below levels of concern and the entirety of its drinking water supply never reached toxic levels, so the city could have taken its time and pondered its options without notifying its residents of the problem in the well.

But the discovery coincided with national news reports about the water quality failures in Flint, Michigan. St. Anthony Village officials decided right away they were determined to solve the drinking water issues and avoid the potential public relations nightmare facing Flint.

So, the city immediately closed down the contaminated well, instituted testing of its water supply above and beyond those required by the state, created a communication plan for notifying residents of its progress, and began making plans for a long-term fix.

“First and foremost, we wanted to make sure we had the public’s trust in our ability to provide safe and reliable drinking water,” says City Manager Mark Casey. “That was important to the Council as a value.”

Ultimately, the city built the state’s first advanced oxidation water treatment plant. The project was the winner of a League of Minnesota Cities 2019 City of Excellence Award.

Learning about the contaminant

The chemical in question was 1,4-dioxane, a clear liquid used as a solvent in the manufacturing of other chemicals and as a laboratory reagent. Deemed an emerging contaminant, it can be released into the air, water, and soil.

Photo of ultraviolet light units
These ultraviolet light units form strong oxidants with hydrogen peroxide to treat 1,4-dioxane in the city’s drinking water.

The grounds of the Twin Cities Army Ammunition Plant in nearby Casey credited officials from Washington, D.C., for quickly flying in to discuss finding a solution. The tone was set quickly — there were no threats of a lawsuit, and city officials didn’t try to gouge the federal government. They just sought a plan to solve the problem.

“We knew this could drag on for years and get into [arguments] you see in other areas,” Casey says. “The Army was very open to dialogue.”

At nearly the same time, staff reached out to its engineering partner, WSB, for its expertise in planning for such situations.

The company began a feasibility study for the city.

The study looked at a number of options, including building newer and deeper wells, merging the water together from all three city wells to dilute the concentration of 1,4-dioxane, and contracting for water from another city.

Also during this time, Casey says the city established open and frequent discussions with residents to ensure they knew what was going on. Staff provided updates through city newsletters, City Council meetings, separate open meetings, and postcard mailings.

Having temporarily shut down the tainted well, St. Anthony Village also implemented some water conservation efforts, such as shutting down a popular splash pad for the summer and limiting the days and times residents could water their lawns.

“That helped get the message out that we were trying to be proactive,” says Casey, acknowledging that such strategies were not always popular during the height of the summer. But while there were some inconveniences, he emphasizes that throughout the planning and construction process, the issue never became contentious enough to reach the local newspaper.

“We knew right away we needed to update residents, so this didn’t create a life of its own,” Casey says. “We wanted to make sure we stayed ahead of this and — not control the message — but make sure we got facts out there.”

Building the treatment plant

Greg Johnson, a principal and water/wastewater group manager with WSB, helped oversee the feasibility study.

He says state health officials have determined that those consuming two liters daily of water contaminated with 1,4-dioxane for 70 years have a 1 in 10,000 chance of getting cancer.

While Johnson says the city has been diligent about treating its water for other chemicals going back several decades, the 1,4-dioxane may have been there for a while. It has been difficult to see until recent years.

“We didn’t have the technology that could detect lower concentrations,” Johnson says.

In all, the city collaborated with MDH, the Army, the Minnesota Pollution Control Agency, and the U.S. Environmental Protection Agency to solve the problem.

Ultimately, the partners decided that building an advanced oxidation water treatment plant adjacent to its existing treatment facility would allow the city to retain control of its own water supply.

It would also be more economical than building the infrastructure to tap into another municipality’s water.

It took just 15 months to design, plan, and build the facility.

“We knew we were up against the wall and we had to expedite this as quickly as possible,” Casey says. “There really wasn’t an option that was second best.”

System can be adjusted as needed

The building allowed the city to implement a new addition to its water treatment strategies that uses ultraviolet light and hydrogen peroxide to create a reaction that breaks the 1,4-dioxane down into harmless water and carbon. The system can handle 3,500 gallons-per-minute. The city can monitor and adjust the amount of water treatment needed at any given time, given the level of the toxins present.

And it ensures not only that residents of St. Anthony Village get clean drinking water, but that there will be no additional contaminant issues with water that continues flowing downstream through aquifers into neighboring communities. Testing has shown that following treatment, the level of 1,4-dioxane in the water is undetectable.

“The council’s desire was to show that the buck stops with St. Anthony,” Casey says. “We weren’t going to kick this down to the neighbors.”

The treatment process likely deals with other chemicals that may exist in the drinking water and, Casey adds, the building was constructed in such a way that if additional chemicals are discovered in the city’s water, it can be expanded to add new cleaning processes without adding another building.

“We can control our own destiny,” he says.

Total commitment from the city

Ultimately, the bulk of the project’s cost was covered by the Army, which agreed to contribute $10.5 million toward construction. The City Council, however, authorized city staff and its partners to find a solution before ever having a committed funding source.

“You don’t mess around with water,” says newly elected Mayor Randy Stille, who was a long-serving member of the City Council at the time. “Clean water is at the top from a health, safety, welfare perspective. It gets priority. Whether we had the money or not, if we had to bond for a new treatment facility for the safety of our community, we would bond for a new treatment facility.”

Stille says he’s most satisfied with the ability to get the problem solved in a fast and efficient manner. Less than two years after the Department of Health informed St. Anthony Village of its contaminated well, the advanced oxidation treatment plant was open.

“The Army was excellent to work with,” Stille adds. “The reciprocation and good will between the two parties was very evident. We’re proud of that.”

 Andrew Tellijohn is a freelance writer.