Aurora poised to double capacity of Prairie Waters riverbank filtration project with federal grant


AURORA | Aurora is planning an expansion to its innovative Prairie Waters project with the help of a $5 million federal grant, a project that city staffers say could recover enough water to support thousands of homes.

The grant, which the federal government says the city is likely to receive, would be used toward the $11.5 million undertaking of digging a new pump station and radial well, which would draw water from below the South Platte River.

“Drought has been something we’re needing to tackle and handle more and more as the years go on, and so having this resource come from the South Platte instead of the mountains is definitely a drought resiliency component,” said Aurora Water staffer Justin Montes, who applied for the federal grant.

“From a drought resiliency standpoint, we are at the whims of the snowfall and the rainfall for our reservoirs and our mountain waters.”

Radial wells consist of a single vertical shaft ending in multiple horizontal shafts that radiate outward like the spokes of a wheel. The radial well and pump station would be part of an expansion to the Prairie Waters project including another radial well that the city plans to dig in 2024.

Aurora Water representatives say the entire expansion has the potential to double the water recovered by the project, which uses wells dug near the South Platte River to collect water that has been absorbed and naturally filtered by the riverbank.

By the time water is collected by the wells, it has already passed through hundreds of feet of sediment beneath the South Platte, filtering out pathogens, organic chemicals and other contaminants. Montes said the process can also filter out debris introduced by wildfires.

The bank filtration process means it takes less work by the city to render the water drinkable. Prairie Waters is currently able to deliver up to 10 million gallons of water in a day, or around 9,000-10,000 acre-feet each year, Montes said.

Once pumped out of the ground near Fort Lupton, the water is filtered using more sand and gravel. It’s then piped to the Binney Water Purification Facility, where it is treated using ultraviolet light, chemicals and activated carbon. The water is mixed with treated Aurora Reservoir water as it leaves the facility and is transported to Aurora Water customers.

Aurora pioneered the use of bank filtration in the United States, becoming one of the first American cities roughly a decade ago to reap the benefits of siphoning water from beneath a riverbed.

The water pulled from underneath the South Platte includes treated wastewater released back into the river by the City of Aurora, which means Prairie Water helps the city get the most out of its existing water rights.

Roughly half of the surface water used by Aurora comes out of the South Platte, while the rest comes out of the Arkansas and Colorado rivers.

Colorado River water is especially scarce, with several growing states relying on the river, prompting the U.S. Bureau of Reclamation in June to ask river basin states to come up with a plan to save 2.4 million acre-feet of water in 2023 to protect levels at Lake Mead and Lake Powell’s reservoirs.

Aurora Water staffers described the expansion of Prairie Waters as an important part of the city’s drought preparations.

Together, the radial wells will be able to recover an additional 5,000 to 10,000 acre-feet of water per year, or enough to supply somewhere between 10,000 and 25,000 homes. Aurora Water currently provides between 55,000 and 60,000 acre feet annually to customers, spokesperson Rory Franklin said.

“We’re always looking for innovative projects that we can use in order to become more drought resilient,” she said. “Water that we already own is obviously the least expensive, so it’s water that we otherwise wouldn’t be able to use that we’re going to be recapturing.”

Aurora’s grant is one of 36 tentatively awarded as part of a $84.7 million drought resiliency initiative by the U.S. Department of the Interior. One other Colorado project was identified for funding — $585,000 to support the installation of 240,000 gallons worth of water storage tanks for the Deutsch Domestic Water Company in western Colorado.

In a news release, federal government officials described the importance of the list of awarded projects that includes Prairie Waters in light of worsening drought conditions affecting the West.

“Today’s funding will assist our local partners as they work to build drought resilience and improve water security for their community,” said Tanya Trujillo, the Department of the Interior’s assistant secretary for water and science.

“As climate change exacerbates drought impacts throughout the Western United States, the Bipartisan Infrastructure Law is advancing our work to invest in innovative, locally-led water infrastructure projects and provide clean, reliable water to families and communities across the country.”

U.S. Bureau of Reclamation spokesman Rob Manning said the federal government plans to work with Aurora over several months to finalize their funding agreement. Montes said the city hopes to solicit bids for construction of the second radial well in the last quarter of 2024, with completion coming roughly a year later.

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