SIOUX FALLS, S.D. (AP) — The developers of a $70 million project to repurpose the downtown rail yard in Sioux Falls say they must rethink initial plans for underground parking because of extensive bedrock in the area.

The Black Iron Railyard project will replace the rail yard with a campus of mixed-use buildings, The Argus Leader reported.

Developers have hit a snag with the discovery of the bedrock and are re-evaluating plans, said Jim Wiederrich, an attorney who represents the developers.

City officials recently deferred a decision on the project's future.

City councilors must still approve a series of measures to allow the project to move forward. Measures include a $2.6 million purchase agreement for the land and declaring the area surplus property.

David and Erika Billion proposed the project in July. The plan cleared preliminary readings in August but must still receive final approval. Their plan calls for a six-story building with space for offices and residential units. The first phase of the project is estimated to cost $32 million, with construction of later phases lasting until 2030.

The Billion family also owns and operates a retail area and other properties in downtown.

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