Preparations Continue for Erection of "Engineering Control Structure"

The Corps of Engineers will use a large (60 feet by 82.5 feet) Engineering Control Structure (ECS) with a Chemical Agent Filtration System (CAFS) during the high probability work.  The ECS will fully enclose the excavation. The CAFS keeps the ECS under negative pressure by continuously pulling, filtering and cleaning all the air leaving the control structure ... The MCE [maximum credible event] for this activity is the evaporative release of one liter of arsenic trichloride over a one-hour period.

If there were no engineering controls in place, the Temporary Emergency Exposure Limit distance for this MCE would be 194 feet, which impacts eight residents and Watkins Hall on American University (AU).  If warranted, due to the highly improbable failure of the ECS and CAFS at the same time there is a release, the Corps of Engineers will implement another precautionary measure for both the workers and neighbors within 194 feet: a Shelter-in-Place alert and notification system.
The Corps'pondent

Vol. 14, No. 1

April 2013 (pg. 1)

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