The Army says using explosives to destroy leaking chemical weapons at a Colorado storage site would cause no significant environmental impacts.

The finding was released Monday. It brings the Army one step closer to destroying an estimated 780,000 shells containing 2,600 tons of mustard agent stored at the Pueblo Chemical Depot outside Pueblo, Colo.

The U.S. is destroying all its chemical weapons under an international treaty. A plant under construction at the Pueblo facility would use robotic technology to dismantle the shells and then chemically neutralize the mustard agent.

The explosives technology would be used for shells that are leaking. It would also be used to destroy explosive components of the dismantled shells

The Army said this year it could take until 2019 to complete the effort.