A lawyer leading the class action lawsuit on behalf of a Black Hawk neighborhood against the state of South Dakota warned current and future homeowners that the entire neighborhood is at risk from an abandoned gypsum mine Wednesday.
Kathy Barrow, a lawyer with national law firm Fox Rothschild representing a group of homeowners in the Hideaway Hills neighborhood, said there is possible misleading information from a 2021 study regarding the risks around houses built above the mine.
“We see people, real estate agents and those kinds of things trying to say, ‘Well, this isn’t by the mine collapse, so this house is fine,’ and that’s just not right,” she said. “We’re concerned about that, and I know people are tired. It’s been two years now and we’re still slogging through litigation and trying to get a remedy for the folks out there. But the answer is not to try to steer other people in it with things that try to quantify risk.”
A sinkhole opened in the neighborhood April 27, 2020, exposing an abandoned gypsum mine and forcing 40 people to evacuate from 15 homes. Since then, Fox Rothschild and another local law firm have performed multiple studies to indicate and find what is in the subsurface.
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Barrow said Fox Rothschild had an evidentiary hearing in state court April 1 and was ordered to submit findings of fact and conclusions for the court’s consideration. She said her law firm will submit documents for June 1 and expect a determination around July and August.
Rob Gerrard, principal owner and professional engineer with Western Engineers, said the 2021 report completed by the local Fitzgerald Law Firm was done using electrical resistivity tomography (ERT). He said the report helped give his firm a target of where to drill.
He said Western Engineers found a lot of inconsistencies in the fill material used to fill the mine. He said the gypsum mine, which was used by the state up until 2001, was an open pit mine and back-filled with material.
“A lot of that material was uncontrolled because that property, when it was recommended, was recommended for pasture land, which was never meant for residential dwellings,” Gerrard said. “That material wasn’t controlled. We don’t know how it was brought in and compacted.”
He said they also found pockets of clay in areas, and gypsum fracture fragments and gypsum powder all throughout the material. Gypsum is moderately water soluble.
Gerrard said when fill materials are brought in for a structure to be built on, they’d be selective of the material and control how it’s brought in as far as how compact it is and how much moisture there is.
He said gypsum isn’t a stable material and does dissolve in water over time. He said because the material was uncontrolled, it could settle or heave, which would cause damage to homes.
Gerrard said even on the surface people can see where the roads are experiencing significant damage, which allows water to infiltrate into the ground. He said there could be more testing, but nothing is scheduled at the moment.
Barrow said if the certification is granted, both parties would get a discovery period like any other litigation.
— Contact Siandhara Bonnet at [email protected] —