Aquifer storage/recharge project moving forward
A plan to utilize an aquifer beneath the airport for water storage and recovery is off and running after years of work on the project.
The aquifer is an ancient remnant of the Crooked River that ran directly under the present-day airport before geological events altered the path of the current river. It is a confined aquifer, so water does not pass through it quickly, making it a good candidate for storing water during the winter when demand is low (about 1 million gallons a day) and retrieving it during the summer when demand is highest (about 5 million gallons a day).
Work on the storage and recovery system started about three years ago, according to Prineville City Engineer Eric Klann, when the municipality ran water and wastewater lines from the valley floor near O'Neil Highway to the top of the rimrock.
Once that work was completed, they started injecting water into the aquifer during the winter to test its storage capabilities. During the 2018-19 winter, they injected about 200,000 gallons. When that endeavor succeeded and they were able to retrieve the water in the summer, they injected 34 million gallons during the 2019-20 winter. Again, the city was able to retrieve and use the water, so this past winter, they put 100 million gallons into the aquifer.
Klann said that a lot of water analysis was necessary during the process, ensuring that the water quality and chemistry was sufficient for storage and recharge. Meanwhile, the State of Oregon has been working with the city on permitting and water monitoring. So far, all has gone well.
"I would say we have been in a testing pattern," Klann said. "All of that has been looking good, and now we are starting to get into more of an implementation phase."
In the midst of this new phase, the city has added more drinking water to its supply. Near the Crook County Fairgrounds, the municipality drilled three shallow wells that combined produce about 2,000 gallons per minute. But in order to use that water, they needed to build a small treatment plant.
"One of the issues we have in Prineville is there are some water quality issues," Klann explained. "It's potable water, but it has taste and odor issues."
Those issues, which are not present at every city well location, are caused by ammonia, manganese, iron and sulfur in the water.
"We are taking that water and running it through a series of biological filters," Klann said, "a fairly inexpensive way to treat the water, and we are pumping that into the system. … That is a pretty big improvement for us. It probably increases our capacity 30% or so."
The addition of the new wells and water treatment, and the implementation of the aquifer storage and recharge system is expected to help the city meet peak water needs for Prineville and do so without having to spend big money to build a large treatment plant.
"It is a very cost-effective way to meet that seasonal demand," Klann concluded.
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