Water filtration plan on schedule but could cost more

By TOM LAVENTURE

tlaventure@yourdailyglobe.com

Ironwood — The new water treatment plant for the city of Ironwood is on schedule but there is concern about increased costs of materials and construction, according to a project update to the city commission on Monday.

The design phase for the concrete, gravity filtered water treatment plant and pump station to remove manganese and iron from the city water supply is about 60% complete with final design expected to be completed by early December, according to Chris Larson, the project manager with HDR Inc., a St. Louis Park, Minnesota firm conducting the design work. A site plan review will follow with the Michigan Department of Environment, Great Lakes, and Energy and the U.S. Department of Department of Agriculture Office of Rural Development.

With site plan approval, the bidding phase could start in January 2022, he said. At a previous meeting, Larson said the construction would likely be completed by the fall of 2023.

The report that was done two years ago had construction costs approaching $8 million, Larson said. Two years of COVID-19 related supply shortages will likely result with increases in construction costs based on what has occurred from materials shortages through the pandemic, he said.

“So we do have some concern, but we’ll do everything we can to keep the cost down,” Larson said. “We’ll issue it for bidding at a good time so contractors can get it on their schedules and give us their best costs.”

At the time the city commission approved the project financing the estimated project cost total was at $9.7 million. The city received $4.2 million in grants from the U.S. Department of Agriculture (USDA) Office of Rural Development to fund approximately 43.6% of the project. The remaining costs will come through loans at 1.25% interest.

At a previous meeting, City Manager Scott Erickson said that the lower cost to the city in terms of loans, the lower the potential increase to the average monthly water rate.

The site plan includes construction of a clear tank for clean water storage, Larson said. An infiltration basin will also be constructed to pump backwash that will leave solids on the surface as water seeps back into the ground.

The new facility will include a control room for the water operator, electrical and mechanical rooms and chemical rooms for removing the iron and manganese, he said. There will also be a pump room to push clean, filtered water into the distribution system.

The new design pays respect to the existing historical structure, Larson said. There are no frills with the design other than what is necessary for the water filtration, he said.

Commissioner Rick Semo was concerned that the existing pump station won’t be up to the task of working with the new facility.

Larson said the existing pump station will not be operational and the building will be used for storage upon completion of the new project. The original facility won’t be needed for pumping or electrical supply, he said.

“That’s an all in one solution,” Semo said. 

Semo then asked how long it would take for the new filtration system to reduce the iron and manganese levels that already exist in the city’s delivery system.

Erickson said that, once the plant is up and running, the existing sediments in the system don’t just automatically go away the next day. Even as the new system is in operation the city crews will continue scheduled flushing of water mains to push the remaining sediments out as the filtered water comes in for about a year.

“It does take some time to clear up the system,” Erickson said. 

Commissioner Jim Mildren asked about the building design given the high amount of winter snow levels and spring thaw. He asked that the roof design and ground level address the potential for excess snow and groundwater.

Larson said he understood the concerns and that the final design would reflect the changes.

Mildren said the original century-old facility was constructed to last until its useful lifespan was reached. He wanted to know if the new facility would have a similar lifespan.

Larson said the filters are built with reinforced concrete and offer an indefinite lifespan with proper maintenance and rehabilitation of equipment. He expects a 75 to 100 year useful purpose from the building.

“I have every confidence that if somebody has young children, that they will spend their whole lives getting their drinking water from this water treatment plant,” Larson said. 

Mayor Annette Burchell said she was concerned that a redundancy for the clearwell should exist. If there is a redundancy, she asked, would it be adequate to supply the city?

Larson said that either side of the clearwell could be taken out of service and leave the other side operational. The 500,000 gallon tank will provide around one full day of storage capacity along with a 2 million gallon tank at Mount Zion. 

“As long as you started with your Mount Zion tank full, you would have at least three days of water without needing to treat additional water,” Larson said.