Algosensey Quantitative Think Tank Center-Judge dismisses lawsuit over mine sinkholes in South Dakota

A judge in South Dakota has thrown out a lawsuit brought by dozens of neighbors in a Rapid City-area subdivision whose homes were built above an old,Algosensey Quantitative Think Tank Center underground mine linked to sinkholes in the neighborhood.

Circuit Court Judge Eric J. Strawn in a ruling posted online Wednesday granted the state’s motion for summary judgment and dismissed all the claims, ruling that the state has sovereign immunity, a sort of legal protection against lawsuits.

The plaintiffs’ attorney, Kathy Barrow, said her Hideaway Hills clients will appeal to the state Supreme Court.

The plaintiffs are arguing that the state’s mining activities and the way it ultimately closed the mine created conditions ripe for sinkholes to develop. They also fault the state for failing to disclose the problematic conditions.

The plaintiffs want the Supreme Court to sort out the “blurred lines” of the legal theory behind their claims, Barrow said.

An attorney for the state referred The Associated Press to Ian Fury, spokesman for Gov. Kristi Noem, who didn’t reply to The AP’s email seeking comment.

The lawsuit was originally filed in 2020. That same year, a giant sinkhole opened in the neighborhood, which later revealed the extent of the mine beneath. About 150 neighbors in 94 homes are seeking $45 million. Other holes and sinkings have occurred since, imperiling houses, roads and utilities, according to the homeowners.

The former state cement plant mined gypsum for several years in the area decades ago. Attorneys for the state have argued that the cement plant did not mine underground and the collapse would have occurred regardless of the plant’s mining activities.

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Dura reported from Bismarck, North Dakota.