Denver Water on Tuesday celebrated the completion of its new treatment plant, the Northwater Treatment Plant, after nearly a decade of planning, design and construction. 

The plant, built along Highway 93 north of Golden, can clean up to 75 million gallons of water per day and was designed to be expanded if needed. Over time, the new plant will replace the utility’s Moffat Treatment Plant, which was built in Lakewood in the 1930s.

“It was time to build a plant that could replace one of our older plants,” said Nicole Poncelet-Johnson, the head of the water quality and treatment group at Denver Water. 

“This new plant will help us better meet the needs of a changing regulatory environment, the impacts of climate change and the need to be more sustainable in our operations,” she said. 

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The Northwater Treatment Plant began operations earlier this year and was completed under budget. 

Denver Water also operates the Foothills Treatment Plant, located near Roxborough and completed in 1983. It’s Marston Treatment Plant, located in southwest Denver, started operations in 1924. Both plants have been updated over their decades of operation. 

The Northwater plant incorporates new technology and lessons learned from other treatment plants. Its design also allows for upgrades to be added as needed.

“The designers and contractors have worked on other conventional treatment plants along the Front Range, and you can see in this plant that they brought the best designs and ideas here to Northwater,” Poncelet-Johnson said. 

Unique elements at Northwater include deeper filter beds, which are used to filter out dirt particles in water. The deeper filters at the new plant can be operated for longer periods of time between cleanings, making them better suited for treating water affected by various aspects of climate change such as wildfires or floods.

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The plant uses ultraviolet technology to help clean the water, technology that reduces the time, space and chemicals needed to disinfect the water for delivery to customers. 

And a generator that harnesses power from the water flowing into the plant, when combined with other energy efficiency improvements, is capable of producing more energy than it needs for operations. 

“This plant helps us be ready for the next 100 years. It’s a great investment in the future for Denver Water and its customers,” Poncelet-Johnson said.

A look back at building the Northwater Treatment Plant 

With the old Moffat Treatment Plant, which started operations in the 1930s, nearing its end life, Denver Water decided to build a new treatment plant along Highway 93 north of Golden, near its Ralston Reservoir. 

The project required installing a new pipeline, more than 5 feet in diameter, to carry water more than 8 miles from the new treatment plant to the site of the old Moffat Treatment Plant in Lakewood. The new pipeline replaced one that dated from the 1930s. The Moffat plant also was modified as it will transition from cleaning water to primarily storing water following the completion of the Northwater plant. 

The new plant, pipeline and modifications to the Moffat facility are known as the North System Renewal project.

Installing the new water pipeline required tunneling under two railroad lines and three major highways, including Interstate 70:

Construction on the Northwater Treatment Plant started in September 2018. 

In the spring of 2019, the new plant was the subject of a senior capstone project for graduating civil engineering students at the University of Colorado Boulder. The students, working in teams, presented their designs for the building that houses the filter systems at the plant to Denver Water’s leaders on the project. 

How did the CU Boulder students do? Watch here:

In 2020, as the COVID-19 pandemic roiled the nation, work at the plant continued with new protocols to ensure workers remained as safe as possible on the job. 

Learn how they did it: 

The summer of 2021 saw the beginning of the massive effort to place the thousands of yards of concrete that would make up two giant concrete water storage tanks, each capable of holding 10 million gallons of clean water. The tanks, now partially buried, are most visible aspects of the plant seen from Highway 93.

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In fall 2021, students from the Colorado School of Mines in Golden visited the site to hear from project leaders about the design and construction of the plant. 

By the end of 2021, the plant had officially passed the 50% complete milestone for construction while the people working on the project had collectively dedicated 1 million hours to the effort. 

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In 2022, the project received an award from the American Water Works Association, the largest organization of water supply professionals in the world. The project was the recipient of the 2022 AWWA Innovation Award, given to utilities that have inspired or implemented an innovative idea, best practice, or solution to address a challenge facing the industry. 

In 2023, construction of the Northwater plant received national recognition from the American Public Works Association for its commitment and accomplishments around safety, including protecting the health of hundreds of workers on the project during the COVID-19 pandemic. 

The summer of 2023 also saw the completion of the two giant concrete water storage tanks and roofs put on the buildings. 

As the project was nearing completion, it was an opportunity take a video tour of Northwater’s ultraviolet light disinfection capabilities. 

Take a tour: