Extensive Drilling Operation Underway to Explore Hideaway Hills Sinkhole Risks

Core sampling will answer key questions about extent of shuttered mines as sworn deposition testimony begins in lawsuit 


RAPID CITY, S.D. – Drilling operations begin Monday at dozens of sites in and around the Hideaway Hills neighborhood in the most extensive and definitive subsurface testing to date to determine the extent of danger caused by the state’s improper reclamation and maintenance of underground mines.  


The drilling operation gets underway just a week after the Fox Rothschild legal team representing Hideaway Hills property owners began taking sworn deposition testimony from designated state officials and a former cement plant executive to uncover precisely how the state-operated gypsum mines were shuttered and why the state failed to take action to protect homeowners.  


The lawsuit is the only litigation related to sinkhole damages to survive in the 4th Judicial Circuit Court and the only lawsuit seeking accountability from the state of South Dakota. The legal team is moving forward to seek class certification in the coming weeks. 


“These homeowners deserve answers to some very serious questions,” said Fox Rothschild lawyer Kathleen Barrow. “What we learn will be used for the benefit of all the residents of Hideaway Hills.” 


In April 2020, a large sinkhole opened up in the neighborhood, prompting the evacuation of several households. Many homeowners remain unable to return to their homes, while property owners throughout the neighborhood have been unable to sell and have seen property values plummet. 


The state removed approximately 8,619 tons of gypsum from the old mine under Hideaway Hills, and a total of 135,227.58 tons of gypsum in total before the mines were closed and the land sold to a developer.  Records show that 275,227.58 tons of soil were disturbed or displaced in Hideaway Hills before it was sold to land developers.  Based on tonnage removed from underground, geologists estimate that the old mine extends substantially beyond the sinkhole evacuation zone and is at least twice the size of the area that can be accessed from the sinkhole.  


A series of sites will be drilled in two phases to a depth of up to 150 feet. Core samples will provide definitive proof of the extent of underground voids, as well as the integrity of underground mines, pit mines and strip mines that were backfilled with non-native soil. 


The operation is part of a lawsuit filed on behalf of Hideaway Hills homeowners, which is proceeding with a series of sworn depositions of state officials and a former executive of the state-owned Dacotah cement plant set to begin next week. The lawsuit charges that the state failed to properly remediate the land at Hideaway Hills to support structures and also failed in its duty to provide subjacent support of the land to protect the owners of the surface property. 


The case is Andrew Morse and John and Emily Clarke et al. v. State of South Dakota et al., No. 46CIV-20-000295 in the Circuit Court, 4th Judicial District, County of Meade, South Dakota.   


Fox Rothschild has grown to a 950-lawyer national law firm with 27 offices by focusing on client service and responsiveness and by attracting bright and creative lawyers who know how to deliver. More information at foxrothschild.com.    


Media Contact:   

Robert Tharp 



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