KU News Release

KU graduate student charts sinkholes that undermine a vital Kansas highway

LAWRENCE — A young University of Kansas researcher raised on a family farm in Clay Center is making U.S. 50 a safer highway and could save Kansas taxpayers a bundle of money in the process.

A.J. Herrs, a first-year master’s student in KU’s Department of Geology, is mapping sinkholes that underlie and deform the roadway near Hutchinson. Damage occurs to U.S. 50 as massive underground salt beds there are dissolved by groundwater, leaving voids that cause surface subsidence.

“There are two prominent sinkholes where U.S. 50 is being affected,” said Herrs. “It’s a major transportation corridor to connect Hutchinson with the Interstate. It’s been repaved several times over the past decade because of the subsidence.”

With funding from KU’s Transportation Research Institute, Herrs plots the surface of the sinkholes precisely using state-of-the-art technology called LiDAR, for Light Detection and Ranging. Use of the remote sensing device is a unique opportunity for a graduate student, since many universities cannot provide such expensive gear. The apparatus looks something like a space-age lunchbox set atop a tripod. The U.S. military and archeologists often use LiDAR technology.

“Basically, we set up the scanner at several points in the study area and we just tell it where to scan and it does all the work,” Herrs said. “By doing that, we can spatially constrain where the sinkholes are and how fast they’re sinking.”

The underground salt near Hutchinson comes from the Permian era, 299 million to 251 million years ago, when much of Kansas lay beneath a seaway. Today, the salt from the ocean water remains — and there’s a lot of it.

“The main area where all these problems occur is where the Hutchinson salt member underlies the surface, and that takes up about 37,000 square miles of the subsurface of Kansas,” said Herrs. “On the eastern side it’s 200 feet below the surface and it can be up to 600 feet below the surface toward the center.”

As the massive deposits dissolve, underground voids cause surface distortion along U.S. 50, and make frequent repaving a necessity for the Kansas Department of Transportation. It’s a costly process that data from Herrs’ research could make less urgent. Herrs is providing the department with important findings from his investigation of the sinkholes.

“If we know the subsidence rate, we can start to plan for budget reasons and also for just when you should go out and resurface or even build a new road if you need to,” said the KU researcher. “This terrestrial LiDAR can be a very powerful tool for planning future projects and a way to go in and scout an area and get a good feel for what’s going on where surface subsidence has been known to occur.

Herrs said there was no immediate hazard to passengers driving along U.S. 50 from the sinkholes. A driver would barely notice a sinkhole when driving over it unless they were paying close attention.

Herrs did recommend one spot as the best opportunity to knowingly drive over a sinkhole in Reno County. “You’ll notice a very subtle swag in the road as you drive over Brandy Lake,” he said.

A native Kansan from with family roots in the Philippines, Herrs grew up on a small family farm in Clay Center. Working the soil, Herrs became an “amazed with the outdoors” with a special interest in geology. He chose to come to study in Lawrence after earning a bachelor’s degree at Kansas State University, drawn to KU by its proximity and prowess in his field of interest.

“Being close to home and being familiar with the area, KU was a good opportunity to stay in the state and to get a better feel for Kansas geology,” Herrs said. “There’s definitely a lot of opportunities within the Department of Geology here — and a lot of funding within the department.”

Although he is early in his postgraduate academic career, already Herrs plans to continue work on surface deformation and is expanding his horizons beyond Kansas. He mentions mountain belts in both Tibet and Argentina as areas of future academic research. Post graduation, he also may seek a career in the oil industry.

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