Lewiston to replace 100-year-old water treatment plant

The City of Lewiston has approved $27.5 million to construct a new water treatment plant retrofitted to part of the existing facility. The existing facility — initially constructed about 100 years ago — will “largely be demolished.”

The current water treatment facility is 74% beyond its useful life, having been built in 1924 and receiving minimal upgrades since 1979, said Carol Maurer, public information officer for the City of Lewiston. About 1.5 billion gallons of water from the Clearwater River is pumped annually for drinking water and irrigation.

“(This) means reliability is at risk (and failure is possible),” said Maurer. “Staff has done a phenomenal job providing upgrades.”

Following a proposal request process last year, the City of Lewiston selected IMCO, based in Washington, to lead and construct the water treatment plant, and Stantec, based in Edmonton, Canada, to design the project. Both companies have worked together before, increasing partnership projects in the past 10-15 years, said Fred Simmons, operations and project manager with IMCO.

Prior to starting the project, the City of Lewiston and IMCO participated in several “pretty intense technical” workshops together, said Alannah Bailey, engineering project supervisor. IMCO submitted the proposal after that. The city had initially thought a new water treatment plant would have to be built and was the only option.

“What really stood out (about IMCO) was some innovative thinking, some new approaches the city had not thought of,” Bailey said. “We are enjoying the partnership; we are really happy with their performance; we think it’s going to be a real good project.”

“We think they picked the right team,” Simmons said with a smile.

The part of the facility that will be demolished primarily focuses on processes called sedimentation and filtration, said Bryan Black, senior civil engineer for Stantec. What will remain is the computerized and other operation-related parts of the building, such as a laboratory, staff locker rooms and a water pump station that supplies the treated water.

Lewiston voters approved a $42 million bond measure in May 2019 to partially fund the new water treatment plant, as well as other water-related needs like a new well, currently being drilled, and a new reservoir, currently being designed, and a $28 million bond measure for wastewater treatment plant improvements. The city also secured a low-interest loan, with an interest rate of 1.5%, through the State Revolving Loan Fund and a grant from the Department of Environmental Quality.

The interest rate would have been around 3% in the bond market, Maurer said. If the system failed before upgrades were in place, the city would have to go before a judge for emergency upgrades. The current solution is projected to save millions.

“We didn’t want to miss out on that opportunity; we had to act pretty quickly,” Maurer said. “Staff worked really hard to come up with the most fiscally responsible solutions for our community. I think the community understood…that this was the best option.”

Stantec started designing the water treatment plant in January of this year, and construction is planned to start in the fall of this year. It is on track to be completed in spring 2023. About 30% of the design has been completed, said Black.

“The city has been planning this for probably a decade; they’ve done a great job in the planning and securing the financing for it,” said Black. “There’s no question it has to be done.”

The water treatment plant is expected to provide reliable drinking water for the next 20-40 years, according to project leadership, and Black added that the system’s current piping structure will not need to be upgraded just yet to accommodate the plant’s increased capacity. At its peak during the summer, the plant processes eight million gallons of water a day to just over 5,800 users (residential and business). The new plant will have a capacity of 10 million gallons a day, with the opportunity to expand up to 16.5 million gallons a day, which will help accommodate future growth of the city.

IMCO plans to use Building Information Modeling, commonly called BIM, to help the client visualize the new plant and how it operates in the square footage. GPS and other equipment will minimize needs for survey crews while ensuring accuracy of everything being put into place.

“Every square foot of real estate is precious,” Simmons said. “We want to model and show to them before we move into construction. The City of Lewiston has taken a lot of time to (look into) the most suitable, reliable and most efficient procurement process for giving them and the community a good water treat plant.”

Black added the new microfiltration system is innovative, compared to a granular filtration system. This highly automated microfiltration system is intended to ensure better health by protecting the public from microorganisms.

As the majority of the current water treatment plant is being demolished, and the plant is retrofitted with new construction on the existing site, water users will receive their drinking and irrigation water through a system of wells and mobile water treatment trailers.

“It’s obviously a necessary project for sustainability and being able to provide clean water to homes (and) businesses,” Maurer said. “We appreciate our community members so much, understanding the need that is there, and we appreciate our partnership with the community in providing this essential service for years to come.”