A leak in the Umatilla Chemical Agent Disposal facility Monday because of an error has stopped work at the facility while crews determine what caused the a leak.

Plant manager Tim Morton said the bolts that hold the valve in place were not tightened enough and it created a small leak in a three ton HD mustard gas container, Morton said.

“We stopped work immediately,” Morton said. “We’ve made some procedural changes. We are not taking any risks.”

No one was affected by the leak as workers inside are wearing protective suits, Morton said.

The plant will not start operation up again until “all the pieces are in place,” Morton said. The leaking ton container was burned over night.

The facility is sampling 120 containers for mercury and other hazardous materials for the Oregon Department of Environmental Quality.