Industrial Silo Fire and Explosion (Iredell County, Charlotte, NC - December 21, 1997) » Lessons Learned

1. Backdraft-like explosions in oxygen-limiting silos can occur wherever the product is capable of burning and the air is limited.

   In an agricultural setting, this type of silo has been the site of explosions which have taken the lives of firefighters. The mechanism of these explosions are a backdraft-like phenomenon, which is the result of oxygen-containing air being introduced into areas built-up of heat and gases from incomplete combustion needing only a source of oxygen for a violent combustion explosion. This explosion was possibly aggravated by the presence of wood dust, which may have added to the fuel load in the form of finely dispersed combustible particles.

   Oxygen-limiting silos pose explosive hazards regardless of their use and application. In deep-seated fires of shredded combustible material, regardless if it is silage, wood chips or dust, the potential exists for fires to reach smoldering stage of high heat and low oxygen. Backdraft-like explosions have occurred in silos that have been converted to conventional-type agricultural silos because of the strong integrity of seams and joints in the shell, which are designed to prevent air incursion.

2. Hazard and risk assessment procedures should be completed to determine the best attack strategy as to either offensive or defensive mode as well as placement of personnel and attack hose streams.

   Incident commanders need to carefully evaluate the hazard and risk involved. Defensive tactics or direct aggressive attack may be indicated in cases of high life safety hazards, high property-loss potential, or extreme potential for fire extension. If the fire is contained, or is not threatening life or high property loss, measures to greatly minimize the risk to firefighters should be utilized. Unstaffed hoselines, standby operations, or other low risk-level tactics could be considered.

3. There were several gaps in the chain of communications between the incident scene, Communications, and assisting units. This hampered the effectiveness of rescue operations.

   Fireground units were on non-repeating tactical channels not commonly monitored by Communications. The Statesville Fire Department operates on a separate radio channel so critical information from the scene was not available. Periodic situation updates have provided during the operation prior to the explosion would have been beneficial in providing background information to Communications. . More detailed situation reports from the scene could have been reported to Communications after the explosion. Important information could have been relayed to units responding to assist in the rescue effort. This information could have given assisting units a clear picture of the number of injured, severity of injuries and means of entrapment.

4. Ladder pipes, tower ladders, or telesquirts could have been utilized to safely apply water with less risk to personnel.

   In a case where the risk assessment indicates low life or property loss potential, and the structure presents a possibility of explosion, remotely operated devices could be used to safely apply large quantities of water to complete a flooding and penetrating extinguishment effort. The strategic objective of prevention of fire extension to exposures can be safely accomplished with remotely operated master streams.

5. A well-defined command structure with a safety officer and accountability of all personnel should be in place at all fires, even into the overhaul and demobilization stage. All personnel should be subject to an accountability system with the safety officers monitoring the activities and whereabouts of all personnel on the site. In addition to supervising accountability of personnel, the safety officer can play a major role in the risk assessment process

   At the time of the explosion, there was no safety officer in the command structure to account for all personnel operating on the scene or in the area providing support services. When the explosion occurred, one of the major initial problems was the accounting of all personnel on the site. This was difficult without an accountability system and added to confusion at the site. The duties of the safety officer include the management of risk on the fireground. Recognition of the oxygen-limiting silo's explosive potential and the minimal risk to property by the original situation would have fallen under the duties of the safety officer. The safety officer can also mitigate some of the burden on the incident commander and make that job less fatiguing.

6. Unified command, which includes non-fire emergency managers, is essential for the successful resolution of a complex, long-term operation requiring extensive resources and generating a high level of media interest.

   According to dispatch and incident management protocols, the Emergency Director, EMS supervisor, the Fire Marshal, and the County Sheriff are notified of major incidents that may require response for coordination of resources and technical assistance. The Fire Marshal of Iredell County responded immediately after the explosion and stopped enroute to procure the services of a heavy construction crane. The early response of the crane was instrumental in stabilizing the rescue situation and was a factor in the successful removal of both trapped firefighters. The ability of the Emergency Management Director to coordinate non-fire resources was instrumental in incident operations as well.

7. Technical rescue personnel from neighboring organizations should train together as a team as these operations are resource-intensive and require high maintenance of skill levels.

   At this incident, personnel from the various departments on the scene, as well as the Statesville units had successfully completed training courses beyond the basic technical rescue classes. The equipment, in the form of harnesses, line, hardware and the aerial tower, was of superior grade and type. However, the groups had not trained together nor adopted standard operational evolutions. Personnel interviewed indicated this was an issue and plans are underway to develop standard evolutions and train as a unified technical rescue effort across organizational boundaries.

8. The use of personal protective clothing included the deployment of Class III harnesses prevented more serious injury and facilitated rescue.

   The use of full turnout gear including coats helmets and SCBA for the three firefighters on the silo roof prevented more serious injury from the explosion. While the anchor point for the harness attached to the three on the roof failed in the explosion, the use of harnesses facilitated rescue after the explosions. They eliminated the need for affixing additional knots and belts to rescue the injured firefighters. The harnesses performed as designed and were not damaged in the explosion