Federal report helps detail size, speed of salty plume headed for Wichita’s water wells
08/07/2014 7:16 PM
08/13/2014 12:34 PM
The headline of a news release issued Thursday by a federal agency seemingly warned of doom and gloom for Wichita:
“Chloride Contamination of Wichita’s Water Supply Inevitable Unless Actions Taken.”
The declaration came with the release of a report by the U.S. Geological Survey. The city had contracted with USGS to study the salt water plume that for decades has been moving toward the well field used to help supply water to Wichita.
“The headline sounds a little alarmist,” said Alan King, the city’s director of public works and utilities. “This is not an urgent problem. We’ve known about it for some time.”
Under current steps being taken by the city to slow the plume’s progress, King said it’s true that eventually the salt water would reach the wells.
But, he noted, future actions are being considered that would prevent that from happening.
“That’s why we needed this report,” King said. “It helps us so we can start to formulate some long-range plans.”
The problem is significant. The city draws about 40 percent of its water from wells in the Equus Beds north of Wichita.
Some of the report’s key information showed that the salt-water plume had traveled one mile in 18 years, from 1990 to 2008. The plume is still a mile away from the well field, and it moves about one foot per day, according to the USGS report.
Using that information, King said “conservatively” it would take between 10 to 20 years for the plume to reach the northern part of the well field.
But even after reaching the well field, it wouldn’t contaminate the wells for another 20 years because the city could take steps to dilute the salt water, King said.
“This is a long-term issue,” he added.
The plume of salt water came from oil and gas activity near Burrton, northwest of Wichita. From 1931 to 1942, brine that came out of the ground with oil or gas was put in evaporation ponds.
In 1984, a task force of numerous agencies determined that 1.9 million tons of salt produced in the brine during that 11-year stretch seeped into the ground water, said Andy Ziegler, director of the USGS’ Lawrence-based Kansas Water Science Center.
Since the mid-1940s, brine has been injected into disposal wells that go 5,000 to 6,000 feet deep. Fresh water is found about 250 to 300 feet below the ground in the Burrton area, Ziegler said.
Meanwhile, the salt water that seeped into the ground water has been slowly drifting to the southeast because the bedrock slopes that way, King said.
In 2006, the city started the Aquifer Storage and Recovery project (ASR), which pulls water from the Little Arkansas River, treats the water and stores it in the aquifer.
That accomplishes two things: puts more water in the wells for use by the city during a drought and slows the progress of the salt-water plume.
Plans call for the city to enhance the ASR project so that it could double the amount of water it stores in the aquifer, although the river’s flow also dictates the quantity.
The city is looking to the proposed one-cent sales that’s on the Nov. 4 ballot to fund that ASR improvement, which is projected to cost $200 million to $250 million, King said.
Another solution would be to remove the plume entirely, the USGS report said. King noted that would be very expensive.
The plume covers about 30 square miles and is about 200 feet thick, Ziegler said.
Another option would be treating the water – by using desalination plants – after the plume had reached the well field. That also would be expensive and farmers wouldn’t have those plants available to treat water they use for irrigation, King said.
“That’s a good reason to work with the state to find a solution – not only to protect our interest but also agriculture’s interest,” he said.
The city has contracted with USGS to do studies on water issues since 1994. It took about a year to complete the most recent report.
“This has helped define how big the problem is,” King said. “This clarifies a lot of things.
“We have some time and some options. But if we’d waited to the last minute, those options would have been gone because we wouldn’t have time to develop the funding.”
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