WICHITA, Kansas — A federal report says chloride contamination from oil and gas activities near Wichita's groundwater wells is inevitable unless steps are taken, but the city says the problem is not urgent because of the nature of the contamination and plans being developed to deal with it.
The U.S. Geological Survey said in a report Thursday that past oil and gas activities near Burrton, which is northwest of Wichita, have created a plume of high-chloride groundwater that has been moving for decades toward the Equus Beds aquifer, groundwater wells used by the city. The city asked the USGS to study the plume because high chloride levels make water less usable for drinking or crop irrigation without additional treatment, The Wichita Eagle reported (http://bit.ly/1sES2Kf ).
From 1931 to 1942, brine that came out of the ground with oil or gas was put in evaporation ponds. 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, said Andy Ziegler, director of the USGS' Lawrence-based Kansas Water Science Center.
The plume, which is moving about one foot per day, covers about 30 square miles and is about 200 feet thick.
Alan King, Wichita's director of public works and utilities, said the problem, which the city has known about for "some time," is not urgent. He said that while it's true the plume would eventually reach the wells, 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."
King said it would take 10 to 20 years for the plume to reach the northern part of the Equus groundwater well field. He said once the plume reached the well field, it wouldn't contaminate the wells for another 20 years because the city could take steps to dilute the salt water.
The city is also looking to a proposed one-cent sales tax on the Nov. 4 ballot to fund an Aquifer Storage and Recovery project, 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.