New Grand Forks water treatment plant is higher tech, but hopes to stay under the radar

Apr. 10—The white clouds that form and then dissipate in a glass of Grand Forks water shortly after it comes out of a faucet might be the most noticeable feature of the city's water supply.

It's dissolved oxygen, according to Fred Goetz, who supervises Grand Forks new $150 million water treatment plant, and the clouds form when the relatively cold water coursing through the waterworks system warms up as it heads into an apartment or home. Other than the clouds and the occasional, sometimes angry, calls about them, Goetz and other staff at the new plant and its predecessor generally work unnoticed. Goetz hopes to keep it that way.

The new plant is a "hybrid" design, meaning it can filter and clean river water with a relatively new system of membranes or a more conventional system that relies on lime softeners. Water that travels through the membranes ends up with a different pH value than water that is treated with the lime, which means a different process to ultimately make it drinkable. Goetz said consumers shouldn't be able to tell the difference between one process or the other when they use city water.

"If they do realize that I'm doing something," he said, "then I'm probably doing my job wrong."

Plant workers moved into their new building in May but didn't start pumping water into the city's distribution system until July 17, when Mayor Brandon Bochenski ceremonially cranked open a valve in front of a group of city staff and contractors.

The plant is a "once-in-a-century" project, Bochenski said at his first state of the city address last month, and it's designed to expand as the city grows: water generally enters the building's west side and is processed through it eastward before it is pumped to Grand Forks homes. The building is designed to be expandable north and south to accommodate more filtering and treatment equipment.

Plant staff work in pairs, testing the water at different points in their system, making sure equipment is operating correctly, and monitoring the entire plant from a humming control room they've nicknamed "the conn." Workers are almost exclusively using the more modern system of membranes to treat Grand Forks' drinking water, and they typically pump about 7.5 million gallons of water each day throughout the city. The more conventional lime system is ready to kick into gear if the membrane system fails or gets overwhelmed.

"We decided to do a hybrid plan so that we can always send wet water to you as a customer," Goetz said. "We piloted membranes for five years to make sure that they're going to work for us, but ... it's something that's new, and being conservative North Dakota, we wanted to make sure."

Beyond its monumental up-front cost, the new plant, which sits on the western edge of the city, costs more to operate than the old one adjacent to the Red River. Goetz and Melanie Parvey, Grand Forks' waterworks director, both said it's difficult to quantify how much more expensive the new plant is, partly because it hasn't been in operation for a full fiscal year. Still, Parvey and other city administrators bumped up their water treatment budget from $5 million in 2018, before construction of the new plant got underway, to $5.5 million 2021, which will be its first full year in operation.

But, costs aside, the membrane system is more efficient than the lime one, and the water it produces is considerably cleaner, even if it looks the same to the naked eye. The old water treatment plant, which exclusively used a conventional treatment system, would take in water that was measured at about 70 nephelometric turbidity units — a metric used to gauge cleanliness — and clean it to about 0.10 "NTU." The new plant can get that number down to 0.02 NTU.

The difference between those figures, like any day-to-day differences in plant operation, shouldn't be noticeable to residents, Goetz said, but it's meant to be a hedge against "emerging contaminants" in drinking water across the United States, such as fertilizers, pesticides, medicines that people flush down their drains, and the polyfluoroalkyl substances — "PFAs" or "forever chemicals" — that have become a problem in other Midwestern cities, such as Bemidji, Minn., where water wells near a regional airport were contaminated by firefighting foam that contains PFAs.

Sulfates, for instance, can flow from the Devils Lake basin into the Red River south of Fargo, then north into the Grand Cities' drinking water. Ingested in high enough quantities, those sulfates can be a laxative. Conventional lime filtration can't catch them, but the plant's newfangled membrane system can, Goetz said.

The new plant also can filter out PFAs, but, as of a 2018 test, they have yet to appear in Grand Forks' water supply. The city is set to test for them again in the next few years, depending on when the federal government updates its drinking water regulations.

"Yes, it costs more to treat the water, but we are protected now from future contaminants," Goetz said. "And the goal when we started this facility was for you, as Joe General Public, not to be able to tell the difference."