Following a longer-than-anticipated drilling process, the city of Cottonwood’s test injection well adjacent to Verde Valley Fairgrounds is complete. “Late last night, we finally finished drilling the well,” Natural Resources Director Tom Whitmer said Wednesday, Nov. 29 “We elected to go down to 800 feet rather than 1,000.”
The injection well is intended as a solution to a problem discovered in June, when Glendale-based Pineview Consulting determined that direct underground injection at the yet-to-be-completed Riverfront Water Reclamation Facility would not be possible.
That test well went artesian due to the shallowness of the aquifer under Riverfront Park. As a result of the failed well, the city of Cottonwood was forced to admit it would not make good on one of its original claims in building the reclamation facility — that a major portion of the A+ quality reclaimed water it produces will be injected below groundwater sources at Riverfront.
According to Whitmer, finding out if an injection well will work at the city’s site adjacent Verde Valley Fairgrounds — well over a mile from the Riverfront Water Reclamation Facility — took longer than anticipated by nearly a month. The city’s contractor for drilling the well, Camp Verde-based KP Ventures Well Drilling and Pump Co., suffered a number of setbacks.
“I think this was a ‘well from hell’ for them. Everything that could go wrong went wrong,” Whitmer said, adding that drilling was significantly stalled due to collapsing formations around the drill bit followed by inflowing water at 300 feet. “I give them a lot of credit for working with it.” Issues continued to plague the drilling even after that point, Whitmer said, including material loss.
Ultimately, however, the team hit “significant clay layers,” which indicates that the drill reached an appropriate level for injection 200 feet higher than anticipated. Currently, Whitmer is overseeing geophysical logging to determine what kind of fractures and formations exist, allowing him to predict if pumping will work.
From there, he will conduct an approximately 8-hour pump test, monitoring how fast the level of the well depression goes down before stabilizing. The goal of the pump test, Whitmer said, is to pump water at about the same rate the city expects to pump when treated wastewater is coming from the Riverfront Water Reclamation Facility.
A high “transmissivity value” will indicate injection is possible. If the pump test goes according to plan, indicating that injection is possible, Whitmer will proceed to an injection test at a constant rate for four to five days to see how fast the water goes into the aquifer. This will determine how much water the city will be able to consistently inject.
According to Whitmer, his team has not “run into anything that indicates we can’t do this yet,” but cautioned against coming to any conclusion before the full battery of tests is complete. Whitmer said that moving water to the site adjacent to Verde Valley Fairgrounds may be a better long-term solution than the original plan to inject at Riverfront: Treated water will still be used to irrigate local to the reclamation facility, while a portion of the remaining water can be used to irrigate at Cottonwood Kids’ Park.
According to Whitmer, the treated wastewater might even be used by Minerals Research, which is engaged in the demanding process of processing slag for industrial purposes. Whitmer said that pumping the water into Kids Park will not be an issue: The Riverfront facility already has the pumps in place. Buying pipe and laying it in the ground, however, will be a major cost, one the city is currently in the process of determining.
