Thad Allender/Journal-World Photo
Mickey Center, left, and Murray Balk peer into a ground cave collapse caused by undermining in Galena, Ks., measuring 90-100 feet deep. The Kansas Department of Health and Environment’s Surface Mining Section has filled more than 700 coal mine collapse ssince 1996. ‘We get calls every day,” Balk said. “Especially when it rains because more of them open up.”