Mustard agent is the only chemical agent in the Colorado chemical weapons stockpile at the U.S. Army Pueblo Chemical Depot, but it’s not the only concern the Pueblo Chemical Agent-Destruction Pilot Plant has when it comes to protecting the air.

“Other chemicals formed by the neutralization of chemical agent require an advanced system of filters to screen the air that flows out of the demilitarization plant,” said Brian Ramdwar, deputy plant manager, Bechtel Pueblo Team.

The Pueblo plant’s Agent Filtration Area includes 10 filter units, with eight units running in parallel. These units each contain nine banks of particulate pre-filters, carbon filters and high-efficiency particulate air, or HEPA, filters. Air is released back into the atmosphere only after going through the nine filter banks to remove contaminants. A continuously monitored exhaust stack sees 80 to 100 times the airflow of a typical home’s heating, ventilation and air-conditioning system.

The AFA collects the air from the Enhanced Reconfiguration Building, where the projectiles are dismantled, and the Agent Processing Building, where the drained mustard agent is chemically neutralized before it goes through a biotreatment process.

Filter beds in the AFA are monitored closely for various chemical levels, and the filters are changed when those levels begin to rise toward limits set by government health agencies. Technicians at the plant have been changing out carbon filters in these units under an agreement with the Colorado Department of Public Health and Environment that ensures increased public and environmental protection.

“Only a few banks of filters are replaced at a time, meaning the plant does not need to shut down during the change-out,” Ramdwar said.