Photo by Deb Gau Marshall Municpal Utilities Water Operations Manager Jeff Larson explains the pipelines and equipment that will allow Marshall’s city water plant to pre-soften the water.

MARSHALL — It was a big undertaking, but a project to add water softening equipment to Marshall’s municipal water treatment plant is now operational.

Over the next few weeks, Marshall Municipal Utilities staff will be working on taking city water from 35 grains of hardness down to about eight or nine grains, MMU Water Operations Manager Jeff Larson said.

“We are dialing the hardness down as we speak,” Larson said the process should happen over the next few weeks. Larson said MMU is targeting June 1 as the day when Marshall residents can reset their water softeners. “We didn’t want to have people have to adjust their softeners multiple times.”

Larson showed some of the finished construction, including the new water softening equipment, on Monday. The goal for the $11.5 million project, started in August 2019, is to help cut down on the amount of water softener salt residents need to use — and on how much of that salt makes it into the Redwood River. Starting in 2024, the city of Marshall needs to meet new limits on the amount of chlorides released into the river from its city sewage plant. One big source of those chlorides is water softener salt.

“There’s not an easy way to remove chlorides from the waste stream,” said Marshall City Engineer Jason Anderson. The most cost-effective way to meet the new limits would be to help cut down on the amount of salt in Marshall’s wastewater, he said.

The city of Marshall and MMU worked together to plan a pre-softening project at the city water plant. Construction began in August 2019.

“We’re just getting to the end of it now,” Larson said. The project cost over $11.5 million. Marshall received a $7 million state grant for the project, and the rest of the funding came from MMU and the city. The grant funding was a key factor in making the water softening project possible, Anderson said. And while funding the local part of the project did mean a water rate increase of about 17% a year over two years, it’s possible that customers may also save on water softener salt, Larson said.

Further pre-softening municipal water is a new process for the city of Marshall, Larson said.

“It is, in that regard, kind of a new plant,” he said.

Marshall has had hard city water since about the 1950s, when the city started using aquifers that had a bigger water supply, but much harder water.

“It is very hard and very high in iron,” Larson said.

City water treatment plants built in 1959 and 1999 mainly focused on getting the iron out of the water, Larson said. The high iron content wasn’t good for local food production industries that use a lot of water.

The bulk of the new water softening project is in just one room at the water plant, Larson said — but that room has new equipment that allows MMU to precision-mix the lime and soda ash needed to get the calcium and magnesium out of city water.

“It’s a much more efficient system,” Larson said.

“Another big part of this project is the brains of it,” Larson said. He was referring to the control systems for the water plant, which were also replaced and updated.

Even with the new pre-softening system in place, a lot of the process of Marshall’s water treatment stays the same. Raw water from Marshall’s three well fields is aerated and put into clarifiers, where iron and manganese in the water is allowed to settle out. Then the water is treated with carbon dioxide. Under the new softening system, the water is now also treated with soda ash and lime to remove the hardness. The water is then filtered, treated with fluoride and chlorine and pumped into city water mains. The mineral sludge left over from the water treatment process is dried and pressed into solid “cakes.” The dried sludge can be applied on agricultural land to help with soil acidity, Larson said.

Another new addition that was part of the water softening project is a building that holds sludge produced by the water softening process. Pre-softening city water produces 2.5 to three times the sludge the water plant produced before, Larson said.

One big impact the city and MMU hope the pre-softening project will have on Marshall residents is a need for less water softener salt. Anderson and Larson said the city and MMU will be meeting this week to plan out how to inform residents how they could be affected by the water softening project. Larson said MMU customers will receive information along with their utility bill before the June 1 target date, and Anderson said the city of Marshall will likely also use other forms of communication like the city website and social media.

Larson said residents may still need to contact the manufacturers of their own water softeners for more information on how to adjust after June 1.

It’s hard to give advice on how individual customers should adjust their water softeners, because people have different models of water softener, he said.