Town and county officials are moving ahead on a plan to develop aquifer storage and recovery at Rumsey Park.
The preliminary plan includes running treated waste water through an existing drainage stretching from Rumsey Park to American Gulch, creating a seasonal stream that could use aquatic plants.
Mike Ploughe, the town's hydrogeologist, said that ASL Consulting Engineers have met with officials from the Northern Gila County Sanitary District to see if such a plan would be feasible.
Ploughe described the May 12 discussion with county officials as "a kick-off meeting."
The purpose of an effluent program, he said, is to recycle and re-use treated waste water for irrigation and recharge purposes.
It's an ongoing effort that started with the creation of Green Valley Park. This second phase of the project now proposes to take the water from Green Valley Lake and discharge it into the drainage that will go through Rumsey Park.
"At the west end of Rumsey Park, we would intercept the water from the drainage and pump it into a storage facility that would be plumbed to the treatment facility. Following treatment, the water would be injected into the aquifer for storage and recovery at a later date," Ploughe said.
The plants in the stream bed would consume nutrients in the water and would help clarify the water before it goes to the treatment center. The added benefit would be that the stream would satisfy the public desire to have a water feature at Rumsey Park, Ploughe said.
The excess effluent could then potentially recharge the aquifer along the path of American Gulch through the town limits. "We perceive only minor improvements to the drainage," Ploughe said. "And we'll get incidental recharge along the way."
Ploughe said the success of the Green Valley project demonstrates the ability of the town to recharge the high quality effluent produced by the sanitary district. "What we're trying to do is find a place to store the excess of effluent that is currently discharged in the lower American Gulch during the wet months."
He said the town is working with the county on water quality, quantity and permitting issues.
"It's still preliminary," said Ploughe. "We're looking at whether it's doable in terms of the regulatory processes."
The town will be modeling its recharge project on similar systems in Fountain Hills and Scottsdale and will be looking at whether the proposed project would be cost-effective.
Ploughe said the town drilled six holes in 1997 at Rumsey Park as part of the initial testing and drilling phase.
"The original concept of infiltration wells was that they would be used to recharge water back into the ground," he said. "Now we are looking at direct injection as a means of storing the water underground."
In November 1998, the two most permeable wells were selected for infiltration capacity testing. One of these wells was selected for the injection testing to follow.
"That was in March of this year," Ploughe said. "Test results indicate that the well will accept up to 120 gallons per minute of injected water."
"Water levels rose in the observation wells," Ploughe said, "but not significantly. We wanted to see if the ground would accept water and it did."
Ploughe is now analyzing the information in more detail to see if injecting the water will work on a sustained level.
"We're going to analyze the trend of the water level rising over time to assess the effects on the aquifer system," he said.
At this time, the proposed pilot recharge program for Rumsey Park consists of the combined stream channel and injection facilities.
"The concept could still change, however," Ploughe said, "as dictated by costs and regulatory issues.
"Water is such a big issue that we have to be going in several directions at the same time. This isn't the solution. This is just part of it."