HERMISTON A depot chemical operations monitoring crews detected trace amounts of mustard chemical agent vapors Tuesday and Thursday inside a depot storage structure containing bulk storage containers.

Both traces of mustard chemical agent were detected during routine monitoring. The leaking container found Thursday was in a different structure than a similar leaking munition detected on Tuesday.

The storage structure, commonly called an igloo, has a “passive” filter system that prevents chemical agent vapor from escaping outside the structure. However, as a further protective measure, a powered filter system will be installed. The leaking container will be identified, inspected and decontaminated.

Even though the readings are so low they are not harmful to the public or the environment, depot officials notify the public when such incidents occur. They also notify off-post emergency operations centers in Umatilla and Morrow counties, Benton County, Wash., those in Oregon and Washington states, the Confederated Tribes of the Umatilla Indian Reservation and the Oregon Department of Environmental Quality.