death in the - centers for disease control and …and other pertinent documents including the state...

Two Fire Fighters Die and Eight Fire Fighters are Injured from aSilo Explosion at a Lumber Company - Ohio

December 27, 2004A summary of a NIOSH fire fighter fatality investigation

SUMMARY On October 1, 2003, a 44-year-old male volunteerfire fighter and a 42-year-old male volunteer firefighter were fatally injured by a silo explosion at alumber company. The victims responded to a mutualaid call from a neighboring volunteer fire departmentalready on the scene at the silo fire. Prior to theexplosion, fire fighters had opened some exteriorhatches at the base of an oxygen-limiting silo andwere flowing water through the hatch openings witha piercing nozzle. Fire fighters were also flowingwater into the top of the silo via an aerial apparatus.At the time of the explosion, one victim was standingon top of the silo and the other victim was in theaerial basket positioned beside the top of the silo.Eight other fire fighters were injured during theexplosion, two requiring hospitalization. The fatally

injured victims were transported to regional hospitalsvia ambulance where they were later pronounceddead.

NIOSH investigators concluded that, to minimize therisk of similar occurrences, fire departments should

• Train officers and fire fighters on the hazardsassociated with different types of silos andthe appropriate fire fighting tactics

• Develop and implement standard operatingguidelines (SOGs) for fighting oxygen-limiting silo fires

• Ensure that pre-emergency planning iscompleted for silos within their jurisdictions

Additionally,

• Facilities with oxygen-limiting silos shouldensure the proper operation and maintenanceof their silos

The Fire Fighter Fatality Investigation and PreventionProgram is conducted by the National Institute forOccupational Safety and Health (NIOSH). The purpose ofthe program is to determine factors that cause or contributeto fire fighter deaths suffered in the line of duty.Identification of causal and contributing factors enableresearchers and safety specialists to develop strategies forpreventing future similar incidents. The program does notseek to determine fault or place blame on fire departmentsor individual fire fighters. To request additional copies ofthis report (specify the case number shown in the shieldabove), other fatality investigation reports, or furtherinformation, visit the Program Website at

www.cdc.gov/niosh/firehome.htmlor call toll free 1-800-35-NIOSH

Fire Fighter Fatality Investigation and Prevention Program

F2003 Death in the line of duty...32

Silo involved in the incident

Two Fire Fighters Die and Eight Fire Fighters are Injured from a Silo Explosion at aLumber Company - Ohio

Investigative Report #F2003-32Fatality Assessment and Control Evaluation

Fire Fighter Fatality Investigation And Prevention Program

• Municipalities should consider requiring anexterior placard with specific silo informationfor use during fire fighting efforts

• Silo manufacturers and research organizationsshould consider researching the causes andmechanisms of silo fires involving woodproducts and developing engineeringapproaches to reduce the risks to fire fighters

INTRODUCTIONOn October 1, 2003, a 44-year-old male volunteerfire fighter (Victim #1) and a 42-year-old malevolunteer fire fighter (Victim #2) were fatally injuredby a silo explosion at a lumber company. The victimsresponded to a mutual aid call for their aerialapparatus from a neighboring volunteer departmentalready on the scene of the silo fire. At the time ofthe explosion, Victim #1 was standing on top of thesilo and Victim #2 was in the aerial basket positionedbeside the top of the silo. A third fire fighter (FireFighter #1), who was severely injured andhospitalized, was also standing on top of the silo.Seven other fire fighters were injured during theexplosion, one requiring hospitalization. On October1, 2003, the U.S. Fire Administration (USFA)notified the National Institute for Occupational Safetyand Health (NIOSH) of this incident. On October6-7, 2003, two safety and occupational healthspecialists from the NIOSH Fire Fighter FatalityInvestigation and Prevention Program conducted asite visit at the lumber company and met withrepresentatives of the lumber company and the StateFire Marshal’s Office. The victims’ aerial apparatusdamaged in the explosion was also inspected. OnDecember 1-4, 2003, two safety and occupationalhealth specialists conducted further investigation intothis incident. The NIOSH team met with the Chiefsof both volunteer departments, interviewed officersand fire fighters on the scene, examined photographsof the fire ground, and reviewed witness statements

and other pertinent documents including the StateFire Marshal’s report.

DepartmentsTwo volunteer fire departments were involved in thisincident. The incident command department has 23personnel that serve a population of approximately2,300 to 2,500 within a rural area of about 45 squaremiles. The department serves the community from asingle station and receives the majority of its fundingthrough the township.

The mutual aid volunteer department has 30personnel that serve a population of approximately3,500 within a residential and industrial area of about17 square miles. The department also serves thecommunity from a single station and receives itsfunding through the city and township. Both victimswere members of this department.

Training and ExperienceVictim #1 had 14 years of experience as a volunteerfire fighter. He was certified in the State of Ohio asa Volunteer Fire Fighter Level 1-A. Fire FighterLevel 1-A is a 48-hour course developed forvolunteer fire fighters that contains a portion of therequirements for NFPA Fire Fighter Level I.Additional training included confined space rescue,training in propane emergencies, and terrorismawareness.

Victim #2 had 10 years of experience as a volunteerfire fighter. He was also certified in the State of Ohioas a Volunteer Fire Fighter Level 1-A. Additionaltraining included confined space rescue, terrorismawareness, fire fighter safety, farm emergencies,public information officer, and electrical emergencies.

EquipmentThe incident command volunteer fire departmentinitial dispatch response listed in order of arrival onthe scene included:




• Engine 744 (Officer and four fire fighters)• Equipment Truck 743 (five fire fighters)• Engine 745 (two fire fighters)• Tanker 742 (two fire fighters)• Chief (Incident Commander) via personally ownedvehicle (POV)• Assistant Chief via POV• Brush Truck 741 (Officer and fire fighter)

The mutual-aid volunteer fire department 2nd alarmresponse included:• Aerial Truck 6642 (Officer, Victim #1, Victim#2, Fire Fighter #1 and two fire fighters)• Equipment Truck 6643 (four fire fighters)

Additional personnel from both departments arrivedon the scene in their POVs.

StructureThe incident silo (see Photo 1) was located at alumber company that employs 60 full time employees.The facility produces various wood products includinghardwood flooring for bowling lanes, architecturalmillwork, roof trusses and brooms.

The silo was constructed in 1986 and was used tosupply recycled plant material to an electrical boiler.The concrete silo was originally designed as anoxygen-limiting silo but was later modified. The silowas approximately 70 feet high and was 20 feet indiameter. The base of the silo had two doors (oneon each side) to access the auger pit (see Photo 2).The auger was used to unload the silo. The silo wasnormally filled with wood chips and saw dust fromthe plant. The roof of the silo had two round openingseach measuring about 2 feet in diameter. The silowas filled pneumatically as wood chips were blownthrough a tube into the top of the silo through thecenter opening. The other opening had a cover thatwas not in place. On the day of the incident, the silowas filled to a depth of 21 feet with wood chips.

According to the State Fire Marshal’s report, theorigin and cause of the fire was heat generated fromthe friction of a belt on a pulley at the base of thesilo’s auger, which ignited the combustible woodchips. The fire smoldered for several hours prior tothe arrival of fire fighters. The Fire Marshalconcluded that the explosion in this incident was acombination of events that included “at a minimum abackdraft with ignition of the fire gases and a dustexplosion of some degree.”

The incident command fire department hadconducted annual pre-planning for the facility androutinely made 1-2 calls per year to this facility. Thesecalls included three fires in adjacent silos and smallfires in the dust collection system. There were noprevious fires in the incident silo.

INVESTIGATIONAt 0650 hours, a lumber company supervisordirected a plant employee to check the silo becausethere was an odor of smoke in the vicinity. Theemployee went to the silo auger pit and quicklydiscovered the source of the odor when he openedthe access door. The auger pit was filled with lightsmoke and there was a red glow seen within the silothrough the auger port. He quickly exited the pit,shutting the access door on his way out, and reportedto his supervisor that the silo was on fire.

At 0657 hours, the lumber company called 911 toreport that one of the silos was on fire. At 0701hours, Engine 744 was en route with an officer andfour fire fighters. Engine 744 arrived at the lumbercompany at 0703 hours. Equipment Truck 743,Engine 745, and Tanker 742 also arrived within twominutes. (Note: The fire station is less than amile from the lumber company). Upon arrival,fire fighters observed light white smoke coming fromthe top of the silo and moderate white/gray smokethrough the bottom of the access doors. Engine 744was positioned in the parking lot on the east side of




the silo and the crew pulled a 1¾ inch handline tothe northeast side of the silo. Engine 745 was put onstandby to act as a backup.

The crews from Engines 744 and 745 entered thesilo auger pit from the east. Two fire fighters (with a1¾ inch handline) inspected the auger pit and foundsome aerosol cans and a LP gas tank that theyremoved. Next they shut off the circuit breakers forthe electric powered auger motor. The auger accessdoor had warped opened due to heat and water wassprayed into the opening. Two other fire fightersstood on standby on the east side with a charged1½ inch handline. Conditions within the auger pitwere heavy smoke, little visibility and high heat. Themetal auger access door (see Photo 3) was glowingred from intense heat and fire fighters were successfulin cooling down the metal. Burning wood chipsbegan to fall from the auger access door and pile upon the pit floor.

The IC was concerned that the fire would spread toother areas of the lumber company by burning embersand wanted to aggressively extinguish the fire. TheIC wanted to inspect the fire conditions from the topof the silo. Since the silo did not have a cage on theexternal ladder, he determined that it would be unsafefor fire fighters to climb to the top. At 0725 hours,the IC requested an aerial apparatus (Aerial 6642)as mutual aid from a neighboring volunteerdepartment.

At 0728 hours, Aerial 6642 was en route with anofficer and five fire fighters. When the aerial unitarrived at 0736 hours, the crew observed minimalwhite/gray smoke coming from the top and moderatesmoke from the bottom doors of the auger pit. TheIC directed the aerial to position next to the silo onthe north side. The IC and two mutual aid officers(Note: Another mutual aid officer had previouslyarrived on scene via POV at 0725 hours) had abrief discussion and decided to extend the aerial to

determine the structure of the top of the silo and theconditions within the silo. Both victims from themutual aid department and another fire fighter fromthe IC’s department went to the top of the silo in theaerial basket and examined the silo’s condition forseveral minutes. The basket was brought down andthe fire fighters had a conference with the IC andreported that they could not see any flame or thesurface of the woodchips within the silo due to thesmoke.

At the same time the aerial was at the top of the silo,several fire fighters attempted to unload burningwood chips from the auger pit using shovels and smallbaskets. Two positive pressure ventilation (PPV)fans were placed on the west side auger pit doors toremove heavy smoke coming from underneath thesilo. The fans were blowing smoke out so entry couldbe made from the east. The manual unloading anduse of PPV fans was abandoned after several minutesdue to the lack of progress. The auger and otherequipment at the base of the silo could not be usedto unload the silo since the drive belt had beendamaged by fire and the metal was warped from theintense heat. (Note: The electrical supply to thesilo’s auger had also previously been shut off).

At 0815 hours, the IC requested Equipment Truck6643 as mutual aid from the same neighboringvolunteer fire department since SCBA air bottles werebeginning to run low. Truck 6643 had a cascadesystem for filling air bottles and arrived on scene at0824 hours with four fire fighters. Upon arrival, theIC ordered Truck 6643 to park on the east side ofthe silo in the parking lot.

The IC used a thermal imaging camera (TIC) to locatehot spots on the exterior concrete surface of the silo.Hot spots were identified on the east and west sidesabout 15 feet from the ground and were beginningto grow in size. The IC decided to flow water intothe top of the silo via the aerial. Engine 744 supplied




water to the aerial with a 3-inch line and Victim #1,Victim #2 and Fire Fighter #1 went to the top of thesilo in the aerial basket. Victim #1 and Fire Fighter#1 exited the basket onto the top of the silo. Victim#2 remained in the basket. Victim #1 made the hoseconnection to the platform water supply and ran a50 foot section of 1½ inch hose with a 1½ inchdistributing nozzle around the top of the silo. FireFighter # 1 lowered the hose into the access holejust as it was being charged. They sprayed water forabout 5-10 minutes and it is estimated that less than1,500 gallons were pumped into the silo.

At the base of the silo, fire fighters had opened asmall exterior side hatch. They were pulling woodchips from the hatch and inserting a piercing nozzlesupplied by a 1¾ inch handline from Engine 744.The hatch was located below a large hot spotobserved with the TIC. A fire fighter was using apike pole to make a path for the piercing nozzle andanother fire fighter was inserting the 10 foot piercingnozzle into the hatch up through the wood chips. Athird fire fighter was assisting with the hose. Firefighters were alternating positions during thisoperation. Another fire fighter was behind themmanning a charged 1¾ inch handline as a backup.

The IC instructed the aerial crew to change the nozzleto a straightbore and spray water in the southeastsection of the silo based on the growing hot spots.Victim #2 shut the water off and Fire Fighter #1started pulling the hose out of the silo. He recallsthat the smoke was yellowish and remembers hearinga whooshing sound followed by a loud boom.

At the base of the silo, a sudden burst of wood chipsand smoke came out the hatch. This was describedby fire fighters as “like a jet engine taking off.” Otherfire fighters on scene reported hearing a “sucking”sound or a strange “expanding-like” rush. Firefighters on the ground closest to the silo felt aconcussion and the ground shake. Several fire fighters

at the base of the silo near the hatch were thrown tothe ground from the force of the blast.

The explosion occurred in the silo at approximately0850 hours. The top of the silo blew off and landedto the west (see Photo 4 and Diagram). Victim #1,Victim #2 and Fire Fighter #1 were thrown from thetop of the silo and aerial basket (see photo 5) andwere thrown approximately 70 feet to the ground.Victim #1 was found near the basket of a front endloader parked at the base of the silo. Victim #2 wasfound at the base of the west side of the silo. FireFighter #1 fell into a garbage-filled dumpster whichhelped break his fall. Debris rained down on thescene, injuring eight fire fighters and two lumbercompany employees. After the debris had settled,fire fighters recall hearing multiple personal alert safetysystem (PASS) alarms. The IC ordered anaccountability check and radioed for rescue units tocome to the scene. Fire fighters on the sceneimmediately began administering first aid to theinjured.

Victim #1 and Victim #2 were transported to regionalhospitals via ambulance where they were laterpronounced dead. A helicopter transported FireFighter #1 and another fire fighter injured by fallingdebris to a regional trauma center. The incidentcommand department had one fire fighter hospitalizedwith a broken foot and four fire fighters treated andreleased from the emergency room. Fire Fighter #1was hospitalized with a broken arm and leg. Twoother fire fighters from the mutual aid departmentwere seen and released in the emergency room. Twoplant employees from the lumber company were alsohospitalized.

CAUSE OF DEATHSAccording to the county medical investigator’sfindings, the cause of death for both victims wasmultiple blunt force injuries.




RECOMMENDATIONS/DISCUSSIONRecommendation #1: Fire departments shouldtrain officers and fire fighters on the hazardsassociated with different types of silos and theappropriate fire fighting tactics.

Discussion: In this incident, the critical informationthat was not established during the initial size-up ordetermined in their pre-plan was that this silo was amodified oxygen-limiting silo. The IC had successfullyfought a silo fire in the past at the lumber company,however that fire had been in a conventional silo.The tactics and strategies used by fire fighters in thisincident were for a conventional silo. Since the silowas modified, it should have been treated as anoxygen-limiting silo by fire fighters.

There are two types of upright silos: conventionalsilos and oxygen-limiting silos or “sealed” silos.Conventional silos are typically used to store corn,hay or other foodstuff for livestock feed. These silosprovide for the preservation, storage anddisbursement of the feedstock. Conventional silosusually have outside doors stacked up the silo wall.Conventional silos are normally unloaded from thetop.

Oxygen-limiting silos are sealed to prevent oxygenfrom entering the silo. These silos are constructedof steel or concrete and have tightly sealed openingsand hatches. When the hatches are closed and thesilo is filled, the oxygen concentration should beinsufficient to support a fire.

Both types of silos can be found on farms and usedat sawmills. It is critical for fire fighters to recognizethe type of silo involved prior to beginning any firefighting operations. In this incident, the silo no longerhad tightly sealed top hatches (hence modifiedoxygen-limiting) and the amount of oxygen enteringthe silo was sufficient to initiate the explosion.

Recommendation #2: Fire departments shoulddevelop and implement standard operatingguidelines (SOGs) for fighting oxygen-limitingsilo fires.1-3

Discussion: SOGs are a set of written tacticaldirectives that establish a standard course of actionon the fireground. SOGs should include such itemsas fireground safety and guidelines that describe thetactical priorities and related support functions duringsilo fires. Important elements that should beincorporated into SOGs for conducting operationson an oxygen-limiting silo fire include:· Confirm pre-plan information on arrival

· Do not direct water or foam onto the fire throughthe top hatches. This will allow oxygen to enterthe silo and can cause a “backdraft-like”explosion of fire gases.

· Do not enter, breach, or open any external silohatches in an attempt to extinguish the fire.

· If the top hatches are open, fire fighters shouldnot close them if there is smoke coming out fromthe top, especially if the silo is vibrating or makingunusual sounds.

· Lockout and tagout the electrical service to thesilo.

· Roof hatches should be safe to close if the silohas been quiet for several days and there hasbeen no smoke coming from the hatches. Thehatch should be closed, but not securely, topermit the relief of any pressure that may buildup.

· Leave the silo closed for up to three weeks oruntil the fire consumes all the oxygen in the siloand self-extinguishes.




· Establish a collapse zone around the silo, keepunauthorized personnel away from the area,inspect for extension and protect adjacentexposures.

· Some silos have external valves to inject carbondioxide or liquid nitrogen from compressed gascylinders to extinguish the fire.

· If the silo still continues to burn, seek assistancefrom the silo manufacturer.

Recommendation #3: Fire departments shouldensure that pre-emergency planning is completedfor silos within their jurisdictions.4-5

Discussion: Pre-emergency planning, pre-planning,and pre-incident planning are all terms that meanessentially the same thing. By first identifying targethazards (oxygen-limiting silos present high risk to lifesafety and property) within a department’sjurisdiction, the fire department can prioritize andbegin to establish pre-emergency plans for thosetarget hazards. Pre-emergency planning enhanceseffective and safer operations and helps save livesand protect property. The pre-incident plan shouldnot be confused with fire inspections which monitorcode compliance. Pre-incident planning assumes anincident will occur and is one of the most valuabletools available for aiding responding fire fighters ineffectively controlling an emergency.

In conducting pre-emergency planning for silos, firedepartments must recognize the basic silo types aswell as the construction features, materials used,presence of loading devices, other distinguishingcharacteristics, and the hazards associated with eachtype. In this incident, the silo was not identified asan oxygen-limiting silo in the pre-plan. Pre-emergency planning should identify the type of silo,the age of the silo, silo structural integrity, type ofmaterial normally stored in the silo, silo roof structure,

and the silo interior layout. Whenever possible, silosshould be inspected during the construction phaseto aid in assessing the different types of construction,materials, etc. The silo manufacturer should also beconsulted to insure that accurate information isobtained. Some silo manufacturers also have step-by-step instructions on how to extinguish fires withintheir silos.

Additionally,

Recommendation #4: Facilities with oxygen-limiting silos should ensure the properoperation and maintenance of their silos. 1-3

Discussion: Silo owners should do the following toprevent fires and explosions in oxygen-limiting silos:

· Conduct proper maintenance of the silo to ensurethe integrity of the oxygen-limiting features. Thesilo manufacturer should be consulted for properoperating and maintenance procedures for theirsilos. In this incident, the silo was originally builtas an oxygen-limited silo but was not operatedas such.

· Ensure that oxygen-limiting silos have all hatchesclosed and sealed when not being filled oremptied. There is little likelihood of a fireoccurring since the amount of oxygen would beinsufficient to support a fire. In this incident, thetop hatches were not being used prior to the fire.

· Routinely inspect and maintain all loading andunloading equipment to ensure safe operation.In this incident, friction from a pulley belt on theunloader auger was the origin and cause of thesilo fire.

· Consider installing smoke detectors in the augerpit to provide early warning of smoke and fire.




Recommendation #5: Municipalities shouldconsider requiring an exterior placard withspecific silo information for use during firefighting.1-3

Discussion: Information regarding the type of silowould be invaluable to fire fighters should an incidentoccur. Placards should be placed on the silo warningfire fighters that the silo is an oxygen-limiting silo,and should include information concerning the properextinguishing techniques. The placard should alsowarn fire fighters not to use water to extinguish anoxygen-limiting silo fire and have emergency contactinformation. The placard should state “DANGER -Sealed Silo – Water Contributes to Explosion ofSealed Silos.”

Recommendation #6: Silo manufacturers andresearch organizations should considerresearching the causes and mechanisms of silofires involving wood products and developingengineering approaches to reduce the risks tofire fighters.1

Discussion: In this investigation, the State FireMarshall’s report mentions the role of wood productsas a secondary cause of the silo explosion. While abackdraft explosion of the byproducts of combustionis the likely cause of the explosion in this incident,there has been no scientific research on silo fires andexplosions with wood products or sawdust.Modeling the dynamics of oxygen-limiting silo firescould result in greater understanding of theengineering controls necessary for prevention.Engineering controls that would reduce the risk tofire fighters could include remotely operated tophatches, so climbing the silo is not required, installingblast panels to reduce the severity of an explosion,and developing a remote system of pre-piped injectionports for silo extinguishment.

REFERENCES1. USFA [1998]. The hazards associated with

agricultural silo fires. Emmitsburg, MD: U.S.Department of Homeland Security, FederalEmergency Management Agency, U.S. FireAdministration, USFA Publication No. 096.

2. NIOSH [1986]. Preventing fatalities due to firesand explosions in oxygen-limiting silos.Morgantown, WV: U.S. Department of Healthand Human Services, Centers for DiseaseControl and Prevention, National Institute forOccupational Safety and Health, DHHS(NIOSH) Publication No. 86-118.

3. NIOSH [1985]. Preventing hazards in the useof water spray (fog) streams to prevent or controlignition of flammable atmospheres. Morgantown,WV: U.S. Department of Health and HumanServices, Centers for Disease Control andPrevention, National Institute for OccupationalSafety and Health, DHHS (NIOSH) PublicationNo. 85-112.

4. Dunn V [1992]. Safety and survival on thefireground. Saddle Brook NJ: Fire EngineeringBooks and Videos.

5. Dunn V [2000]. Command and control of firesand emergencies. Saddle Brook NJ: FireEngineering Books and Videos.

INVESTIGATOR INFORMATIONThis incident was investigated by Steve Berardinelli,Carolyn Guglielmo, and Mark McFall, OccupationalSafety and Health Specialists, Division of SafetyResearch, Surveillance and Field InvestigationsBranch, NIOSH. A technical review was providedby Ted Halpin, Cornell University




Photo 1. Incident Silo




AUGER PIT ACCESS

DOORWAY

SILO ACCESS HATCH

Photo 2 Auger pit door and hatches

AUGER

ACCESS DOOR

Photo 3. Auger access door in pit




TOP OF SILO SHOWING OPEN CENTER HATCH

APPROXIMATE LOCATION OF VICTIM #1 AFTER EXPLOSION

DUMPSTER FIRE FIGHTER #1 FELL INTO

AFTER EXPLOSION

Photo 4. Location of victims and top of silo after explosion

Photo 5. Condition of aerial basket after explosion




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Location of Top of Silo

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ApproximateLocation of Victim #2

ApproximateLocation of Victim #1

Location of Fire Fighter #1 in Garbage Filled

Dumpster

Location of Hatch where

Piercing Nozzle was inserted

Pickup Truck Damaged in Explosion

Backup Handline

Front End Loader

Parking Lot

Auger Pit access doorway

Diagram. Aerial view of incident scene after explosion

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