Wastewater plant gets high-tech upgrades

After spending the better part of a year under construction, the City of Columbia Falls’ upgraded wastewater treatment plant is running and already the improvements are proving beneficial.

The city made a number of upgrades to its system. The largest include replacing aging equipment, switching from chemical to biological treatment, installing an ultraviolet light system for disinfection and increasing capacity.

Public Works Director Lorin Lowry said the system is working as well as technology allows and is already saving the city money.

“Nothing can be better,” he said.

The city installed a biological nutrient removal system. The system uses specific micro-organisms to remove nitrogen and phosphorus from the wastewater. The water passes through aerated and non-aerated chambers as the organisms work.

Previously, the city removed nitrogen and phosphorus by using chemicals. After treatment was completed the discharge water met current state Department of Environmental Quality standards. Treated water is discharged into the Flathead River.

“The DEQ is expected to set new limits to control the phosphorus and nitrogen that goes into the Flathead River basin,” Lowry said. “Even at our best we knew we would not be able to meet those reduced levels.”

The city also had to improve the treatment plant’s disinfection system. The city had been using chlorine as a disinfectant to treat for E. coli and fecal coliform bacteria. That chlorine remained in the water when it was discharged into the river.

“We had to have the chlorine down to a level that was below what we were able to do,” Lowry said. “Now we no longer have to discharge chlorine.”

The city installed an ultraviolet disinfection system that kills the bacteria with ultraviolet lights.

While checking the system’s performance, crews found that the ultraviolet lights were killing all of the E. coli bacteria. It was re-checked because, at first, it didn’t seem to be possible, Lowry said.

“We’re not sending any E. coli into the river,” he said. “That’s really remarkable.”

As part of the new biological system, the city had to build a new wastewater basin. The old basin has been converted into a storage tank.

Wastewater comes into the plant at varying levels through out the day. In the biological treatment basin, the wastewater levels must remain constant so the micro-organisms work correctly. With the old basin being used as storage, crews can keep that level even by transfering and storing wastewater as necessary.

The capacity of the wastewater treatment plant has also increased. The plant can now handle about 100,000 to 200,000 gallons more per day.

The upgrades to the treatment plant went online in October. Since then the performance of the biological nutrient removal system has been better than expected.

Lowry said it takes operators some time to find the “sweet” spot where the plant operates at its most efficient level and cold temperatures can make it more difficult.

“I’m feeling pretty optimistic,” he said. “It’s doing well in the cold and I only expect it to get better in warmer weather.”

Cost

The city performed a facility study on the wastewater treatment plant about five years ago. The study showed what upgrades would be necessary in coming years.

“We needed to improve performance to keep running and meet new regulatory issues,” Lowry said.

The study showed a projected cost of about $3.5 to $4 million for upgrades. At the time, Lowry said, that number was thought to actually be extremely low based on what other cities had been paying for upgrades.

Even though it was less favorable, the city began looking at a contingency plan that would build only the critical components of the upgrade.

“We were trying to work to get the best system for the city,” Lowry said. “It was best to build the full system, but we were looking at alternatives.”

Then when the economy took a downturn, those figures began to drop. Prices for materials, like concrete and steel, fell.

“It’s unfortunate what happened with the economy, but it was good for the city,” Lowry said. “The stimulus money paved the way to get this done.”

A number of state and federal grants paid for $850,000 of the project. About $1.2 million came from the city coffers. That money included plant investment fees from development. In 2006, the city council approved raising the sewer base rate by $1 per month each year over three years. That rate was implemented as a way of paying for the upgrades.

Finally, $1.8 million was funded through loans. Some of the loans are interest-free because of programs in the American Recovery and Reinvestment Act.

The total cost of the project was slightly more than $4 million. Much of the treatment equipment involved is considered specialty equipment and still remains expensive, noted Lowry.

The grant money also allowed the city to purchase a few items off its “wish list.” A back-up generator was installed that will fully operate the plant in case of a power failure.

Savings

The upgraded plant will likely have a direct savings to the city.

The electricity bill for the plant is already about 50 percent less than normal. Lowry said it’s still too early to tell if that will stay the same, but he’s optimistic.

“We are saving money,” he said.

Switching to a biological treatment system will save the city money because it no longer has to purchase alum for the treatment process. Alum was used to remove nitrogen and phosphorus from the wastewater. The city was spending about $10,000 per year on purchasing alum.

Installation of a new screen and washer system is saving money too. When wastewater first enters the treatment plant it is screened for non-biological material, such as plastic. The old screen was not removing items well enough, which clogged areas later in the treatment process. A new screen has eliminated plugged pumps and the maintenance that resulted.

“We have improved the whole operation of the plant by getting those materials out,” Lowry said.

Previously, when those non-biological materials were removed they were placed into a bucket. City workers had to bag those items by hand and take them to the landfill. A washer has been installed that cleans and bags the items, which are hauled to the landfill by a garbage truck.

“Our crews don’t have to make that weekly trip to the landfill,” Lowry said. “Not having to make those trips, we’re saving money.”

Longevity

The upgrades should keep the plant viable for years.

The plant is operating at the low end of its available capacity.

“It gives us the ability to grow,” Lowry said. “We can handle all of the city and the inventory of surplus lots in the city and probably more than that.”

The improved treatment is expected to meet DEQ standards for discharge in the coming years.

Lowry said depending on how the economy improves and if growth picks up, the city might not need more improvements for another decade.