Study: Abandoned gypsum mine could extend below Interstate 90

June 22, 2021

RAPID CITY, S.D. (AP) — A study shows that an abandoned gypsum mine in Black Hawk that was exposed by a sinkhole in 2020 may extend farther than current mapped areas would indicate.

Mohammad Sadeghi, a professor of geological engineering at Montana Technical University who led the study, says there’s the possibility that the mine extends below Interstate 90. The group recommends that further research be done in the area.

More than 40 people from 15 homes in the Hideaway Hills neighborhood were forced to evacuate after the collapse in April 2020 in Black Hawk, which is located about eight miles northwest of Rapid City.

There are at least two lawsuits filed in relation to the collapse, one of which is one step closer to class-action status.