Reservoir could help aquifer project reach water goals for Wichita

05/17/2014 4:38 PM

07/07/2014 11:30 AM

A storage reservoir near Sedgwick has risen to the top of the options for Wichita’s long-term water future.

The idea is little more than an engineering concept so far: City officials aren’t sure yet how big the reservoir might be, how deep it might be or how much water it might store.

They envision it being constructed on land the city already owns – about 60 acres – north of the existing Aquifer and Storage Recovery Project on 119th Street near Sedgwick. It would not be on a stream or river but would have river water piped to it.

The city already draws water from the Little Arkansas River. That water is treated in the ASR and used to recharge the Equus Beds Aquifer, an underground water source that is also used by farmers.

The ASR plant can capture and treat 30 million gallons of river water a day now. With the reservoir as storage and some equipment improvements, that number could double to 60 million gallons a day, city officials say. The city has no limits on the amount of river water it can capture; that is regulated only by the rate of water flow in the river.

If the plan works, it could generate 3.5 billion gallons of water a year – enough to protect Wichita from drought-related water shortages through 2060, city officials say.

“This fits in beautifully with what we want to achieve,” said Public Works Director Alan King.

The ASR changes and reservoir are projected to cost $376.5 million over 46 years, with $250 million up front to build the reservoir and improve the ASR treatment plant.

That’s far less than the other option still under consideration: Buying treated water from El Dorado Reservoir is projected to cost up to $1.3 billion over the next 46 years for an extra 30 million gallons of water a day.

At first glance, the reservoir option looks good to Tracy Streeter, director of the Kansas Water Office.

“On its face, if you’re building additional storage and divert more water while increasing the operation of the facility, it sounds like we’re headed toward ASR becoming what we all always hoped it would be,” he said.

The complexity of the permit process for such a reservoir varies, Streeter said.

“Building a surface reservoir with a large footprint is no small project. It all depends on the location how difficult the permitting will be,” he said.

“Already owning the land is a big hurdle,” he said. “And let’s say they go ahead and build the reservoir on open ground away from a stream. If they do that, it’s probably a little simpler from the permitting standpoint. They wouldn’t need a stream obstruction permit to dam up the river, and they wouldn’t be in Clean Water Act territory.”

King acknowledges that permits – both federal and state – would be needed. “But something like this, storage for diversion we’ve already been approved for into property we already own, we think the risk for getting the necessary permits is low.”

He said the city estimates it would be five years from the time the project is approved by the City Council until it is operating.

Confidence in project grows

Focus on the ASR as a solution for Wichita’s future water source comes not long after several council members criticized the project as underperforming and voiced doubts that it would be a viable single long-term water source for the city.

King reported in April that the ASR program is generating only half the water city officials had projected – 5,800 acre-feet, or 1.8 billion gallons, a year instead of the projected 11,000 acre-feet, or 3.5 billion gallons, a year. An acre-foot is enough water to provide four Wichita households with water for a year.

But as the reservoir plan takes shape, city officials say they are confident that capturing another 30 million gallons of river water will allow the ASR to produce drinking water at full capacity.

“We were pulling less water out of the Little Arkansas than was originally anticipated, and whether it was dry conditions or the location of the meters that control what we can pull out, we were not getting the full measure of what we were able to draw out on average,” City Manager Robert Layton said.

“The plant is still pretty new in terms of operation and there are still things we’re tweaking to improve efficiencies, but it was primarily an issue on how much water is available to pull out of the Little Arkansas.”

With a reservoir, water from “high tide” river flows could be stored for processing when river flows are low.

The concept for the reservoir comes from city consultants Burns and McDonnell, who had suggested a reservoir during the earlier ASR planning.

“They are a consulting firm who have looked at this before as a possible enhancement to ASR (phases not yet completed) and it was revived because it fits exactly what we’re talking about now,” King said.

The city has not settled on this option for sure. Original plans called for a City Council decision about a future water source on May 27, but Layton said it might take longer than that.

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