    More than 150 homeowners in the Hideaway Hills development northwest of Rapid City are suing Meade County over risks to their properties after a sinkhole exposed an abandoned underground gypsum mine.
      The sinkhole emerged in April of last year and eventually forced about 40 residents in the subdivision in Black Hawk to leave with several of their homes condemned. Studies show as many as 170 homes could be at risk.
       The federal complaint filed Monday alleges several violations of the South Dakota Constitution and seeks damages to be determined by a jury as well as other relief “allowed by law or equity.”
      The suit claims Meade County acted recklessly and in conscious disregard for the risks because it approved the subdivision even though it had full knowledge of the abandoned mine and of a nearby road that was partially collapsed in 2006 by a sinkhole.
Geotechnical studies show there could be water flowing through the abandoned mine and toward Interstate 90, increasing the risk of future collapses and sinkholes.
University of Nebraska-Lincoln geoscientist Mohamed Khalil says the second phase of studies showed the season fluctuation of the groundwater table over the past few decades has created conditions for a sinkhole to develop in any weak spot.