ALBUQUERQUE, N.M. (AP) — A watchdog group wants the New Mexico Court of Appeals to put the brakes on a key construction project at the nation’s only underground nuclear waste repository.

The Southwest Research and Information Center alleges state environmental officials ignored regulations and past practices in giving temporary approval for contractors to begin building a new ventilation shaft at the Waste Isolation Pilot Plant.

The state stands by its decision.

A radiation release in 2014 forced the repository’s temporary closure.

Resulting contamination limited the air flow underground, prompting the need for a new system so full-scale operations can resume.