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A multimillion dollar project to upgrade one of Boulder’s water treatment facilities is underway.

The Betasso Water Treatment Plant, built in 1964, is located in the foothills west of the city. It treats water from North Boulder Creek and Barker Reservoir.

The improvements will increase resiliency and enhance redundancy, primarily for the facility’s corrosion control and disinfection systems. The work was identified in Boulder’s 2019 Asset Inventory and Maintenance, largely because of the age of the infrastructure. The project, estimated at $10 million, is expected to be completed in spring 2024. The city is working with environmental consultant Brown and Caldwell on the project.

Upon completion, the Betasso facility will be equipped with two “treatment trains” that can each handle 20 million gallons a day. In other words, the plant will have the equipment necessary so that half of it can go offline during facility maintenance or emergency repairs without service interruptions.

“We don’t have that dual redundancy that we really do need,” Deputy Director of Operations for Utilities Chris Douville said. “That’s just primarily because of the age of the system.”

While the city’s treatment plant currently does disinfection and corrosion control, Douville said the infrastructure is at the stage where it needs to be studied so improvements can be implemented.

Corrosion control prevents corrosion in the pipes that could lead to harmful materials such as lead being passed on to users — a public health and safety issue, he noted.

“Generally, it’s adding some products to the water so it either doesn’t react or it’s much less reactionary with the pipes as it travels through and works its way through the pipes,” he said.

Another renovation project at Betasso was completed in 2018. That work addressed the treatment areas where the impurities in the water are removed such as flocculation, filtration and sedimentation — “all the things upstream before you get to this disinfection and corrosion control step,” Douville said.

Construction during that project prompted the city’s Public Works Department to add chlorine earlier than normal during disinfection, which led to elevated levels of a potentially cancer-causing by-product in the city’s water supply, according to previous reporting by the Camera.

However, city officials said the exposure was minor and did not ask residents to do anything about the water.

Capital improvement projects such as the current one and the one in 2018 are often completed in phases because the water treatment facility has to remain up and running during the upgrades.

“Because of the cost and complexity, we pretty much have to do that with all of our systems,” Douville said, referencing the phased approach.

Overall, the Betasso project will play a “key role” in meeting the city’s service goals as well as its efforts to maintain a reliable water supply and prevent infrastructure constraints, Boulder’s Public Works Engineering Services Manager Stephen Grooters said in a news release.