Wichita water statistics update

The Wichita ASR water project produced no water in September, despite many days when river flow was adequate.

An important part of Wichita’s water supply infrastructure is the Aquifer Storage and Recovery program, or ASR. This is a program whereby water is taken from the Little Arkansas River, treated, and injected in the Equus Beds aquifer. That water is then available in the future as is other Equus Beds water.

With a cost so far of $247 million, the city believes that ASR is a proven technology that will provide water and drought protection for many years. Last year the city recommended that voters approve $250 million for its expansion, to be paid for by a sales tax. Voters rejected the tax.

September 2015 production

In September 2015, the ASR project recharged no water. The ASR project is able to draw from the Little Arkansas River when the flow is above 30 cfs. As can be seen in the chart of the flow of the river, the flow was above this level for many days. There were 18 days in September when there was adequate river flow for ASR to operate, counting only those days when the flow was above 30 cfs for the entire day.

The city has not provided an explanation as to why the project is recharging so little water.

ASR project background and production

According to city documents, the original capacity of the ASR phase II project to process water and pump it into the ground (the “recharge” process) was given as “Expected volume: 30 MGD for 120 days.” That translates to 3,600,000,000 (3.6 billion or 3,600 million) gallons per year. ASR phase II was completed in 2011.

At a city council workshop in April 2014, Director of Public Works and Utilities Alan King briefed the council on the history of ASR, mentioning the original belief that ASR would recharge 11,000 acre feet of water per year. But he gave a new estimate for production, telling the council that “What we’re finding is, we’re thinking we’re going to actually get 5,800 acre feet. Somewhere close to half of the original estimates.” The new estimate translates to 1,889,935,800 (1.9 billion) gallons per year.

Based on experience, the city has produced a revised estimate of ASR production capability. What has been the actual experience of ASR? The U.S. Geological Survey has ASR figures available here. I’ve gathered the data and performed an analysis. (Click charts for larger versions.)

I’ve produced a chart of the cumulative production of the Wichita ASR project compared with the original projections and the lower revised projections. The lines for projections rise smoothly, although it is expected that actual production is not smooth. The second phase of ASR was completed sometime in 2011, but no water was produced and recharged that year. So I started this chart with January 2012.

2013 was a drought year, so to present ASR in the best possible light, I’ve prepared a chart starting in July 2013. That was when it started raining heavily, and data from USGS shows that the flow in the Little Arkansas River was much greater. Still, the ASR project is not keeping up with projections, even after goals were lowered.

On the chart of monthly production, the horizontal line represents the revised annual production projection expressed as a constant amount each month. This even rate of production is not likely, as river flow varies. In the three years that ASR phase II has been in production, that monthly target been exceeded in three months.

Two nearby charts give an idea of the efficiency of operation of the ASR project. (Click charts for larger versions.) For each month, I counted how many days had a river flow above 30 cfs at every measurement for the day. (The flow is measured several dozen times a day.) If a day had all measurements above 30 cfs, I counted that as a day of adequate river flow. I then calculated the number of days of work actually accomplished using the water produced each month, the number of days of adequate river flow for the month, and the ASR design capacity.

As can be seen in the charts, the ASR project is operating far below its design goal. So far the city has not been able to provide an explanation as to why this project is not meeting its goals.