SIOUX FALLS - The South Dakota Supreme Court has upheld the approval of an air quality permit that would allow a Texas company to begin construction on a proposed $10 billion oil refinery.

Opponents sued the Board of Minerals and Environment, saying the board erred when it approved the Hyperion Energy Center permit because its study did not include a full-blown environmental impact statement.

Attorneys for Dallas-based Hyperion and the board countered that an environmental impact statement was not required and board members took into account all relevant environmental issues.

The high court also ruled that the state did not err in extending a construction deadline for the plant.

Hyperion's proposed refinery north of Elk Point would process 400,000 barrels of Canadian tar sands crude oil each day.

Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

More From KYBB-FM / B102.7