On December 21, 1997, three volunteer firefighters from Iredell County, North Carolina were injured in an explosion in a silo used to collect and store wood waste for utilization as fuel at a cord reel manufacturing facility.  The silo was an agricultural type that had been converted for use as a collector for sawdust.  The structure had been the site of a minor explosion five years previously that had caused no injury.

The firefighters had been directing water into the silo for over two hours from opening in the silo roof when the decision was made to access the wood product inside.  A loud, low order explosion destroyed the top of the silo and endangered the firefighters who had been operating on the roof.  The explosion buffeted personnel operating on the ground as well.

One of the three firefighters operating on the roof was lifted upward and landed back in the silo, his call cushioned by the fill product.  Another was ejected up and outward.  He fell through a trailer shed and landed in an open top trailer filled with wood product.  The third was enveloped by the machinery from the roof top which trapped him at the top rim of the silo.  All three were rescued in the course of a multi-hour operation.  The firefighter who landed in the silo was treated for burns and released from the hospital a week later.  The firefighter who landed in the trailer suffered shoulder and knee injuries requiring surgery, and the one trapped at the top rim of the silo was treated and released for minor burns and bruises.

This incident highlights the need for the recognition of the dangers of oxygen-limiting silos regardless of their use and setting.  Other issues identified are the need for a hazard and risk assessment process in decision-making on the fireground, the importance of site control and accountability, the need for group training in technical rescue operations, the coordination of non-fire department resources and the role of emergency management personnel fulfilling an active role in a unified command structure.