A Portable Local Exhaust Hood System Used to Sample One-Ton Containers Previously Filled with Chemical Warfare Munitions

Abstract

The Tennessee Valley Authority (TVA), Muscle Shoals, Alabama, by contract with the Department of the Army, Rocky Mountain Arsenal (RMA), Denver, Colorado, sampled and verified the decontamination level of 2354 empty one-ton containers (TCs) previously used to store chemical warfare munitions. The TCs had previously been chemically and/or thermally decontaminated and were stored at RMA awaiting removal and disposal. The size and weight of the TCs prohibited placing them inside an enclosure during sampling. To enable sampling containers in place, a portable local exhaust hood was devised to protect sampling personnel and to prevent the release of any residual chemical agent vapors to the environment. Agent vapors captured by the hood were scrubbed through a 200-lb bed of activated charcoal before being released to the ambient environment. Engineers and work crews on site in Denver conceived the hood design and tested three prototypes before obtaining a functional unit. Craftspersons in Muscle Shoals fabricated the hood designs and made modifications. Over a 5-month period in the summer of 1990, TVA successfully sampled 2354 TCs for four chemical agents with no personnel exposures and no release of agent into the environment. Residual contamination was identified in 547 TCs.