A significant deadline to remove all major waste from a key Los Alamos National Laboratory site by Dec. 6 went unmet this weekend.

The deadline Sunday was set in 2005 as part of an agreement between the lab, the state Environment Department and the U.S. Department of Energy. However, officials have said the initial guidelines for cleaning up waste from decades of nuclear weapons production are no longer realistic within the time frame, following the burst of a LANL drum at a waste repository in Southern New Mexico in 2014. That caused a radiation leak that shut down a significant portion of the repository.

The shutdown of the Waste Isolation Pilot Plant near Carlsbad has pushed back the completion of the cleanup project — estimated to cost more than $1 billion.