The Sunshine Mine Fire Disaster
A View From The Inside
by Bob Launhardt
Article below contributed by Patrick Gazewood, Barrick Goldstrike
Note: Due to the age and quality of the original document this information was taken from, there may be typographical errors observed. It should not, however, detract significantly from the whole.
View this in MS Word format
Mine Ventilation Map
An appropriate memorial service on May 2 marked the 25 anniversary of the Sunshine Mine Fire. The tragedy of May 2, 1972 fades deeper into history. Survivors, family, and friends of the 91 men who died now focus on the future. What more, if anything, should be done? What more might be said, or written, or otherwise memorialized? Most of the families and friends of the 91 men who died prefer to avoid discussing details of the losses, especially when inquiries come from the news media. The memories live on. The emptiness does not change. The economic hardship for some of the families continues. That is enough; let the subject rest.
Yet there is a story to be told, a story growing partly out of failure to publicly recognize many of the known heroes. partly out of a desire to correct the record for the sake of history, and partly out of the need to share details about the causes of the disaster: details that will, if used wisely, prevent other mine disasters. Knowledge gained from analysis of the Sunshine fire also has many applications in commerce and industry, as well as in the home. But that story will come later. Today's story begins with a recap of the first hours of calamity on May 2, 1972.
At about 11:40 a.m., Arnold Anderson and Norman Ulrich, mine electricians, detected smoke in the 3700 foot level main drift supplying ventilation air to No. 10 shaft. The 3700 drift connected No. 10 shaft with the Jewell shaft. The two shafts are a mile apart. The Jewell shaft extends to the surface and was the main access route. Work crews descended the Jewell shaft. crossed the 3700 level on man trains, and were lowered to the active development and production areas of the mine. A four deck cage powered by the 3700 level "Chippy" hoist transported men and materials to the bottom of the mine.
Smoke in the 3700 level drift would quickly become smoke in all of the work headings below that elevation, except for the 4800 West Lateral. The 4800 West Lateral received a small volume of ventilation air by way of a four foot diameter bore hole. completed about two weeks before the fire, that connected to the 3700 level near the Jewell shaft. The bore hole was drilled as a pilot hole for future development of No. 12 shaft. On May 2, it was covered with thick, strong lagging to prevent personnel from falling into the opening. The 4800 West Lateral became a safe haven for Ron Florey and Tom Wilkinson until their rescue a week later.
The shouts of warning by Anderson and Ulrich brought a quick response from brothers Bob and Jim Bush, and Harvey Dionne, senior mine supervisors who just finished their lunch break with other supervisors. They were in the "Blue Room"— underground operations headquarters. Next to the No. 10 shaft station. The first challenge was to try to find the source of the smoke. Although the subject of severe criticism, it was a key factor in a choice that had to be made; Should the crew be sent out of the mine through the 3700 Jewell shaft station or up through No. 10 shaft to the 3100 level? If sent to the 3100 level, should they then travel to the Jewell shaft or use the emergency escapeway through the adjoining Silver Summit mine? It would have been chaotic to begin an evacuation without first knowing the route to be followed.
Arnold Anderson. Bob Bush, Harvey Dionne, and Norm Ulrich walked rapidly toward the source of the smoke which was coming from the No. 910 raise. Jim Bush followed after first acquiring a small battery powered locomotive. A decision was made to shut the 3700 level fire door adjacent to the Jewell shaft, consistent with the mine fire plan. Evacuation of personnel would then be by way of No. 10 shaft to the 3100 level. Harvey, Jim, and Norm proceeded toward the Jewell shaft to close the fire door. Arnold and Bob returned to No. 10 shaft to facilitate the mine ë Arnold and Bob perished in the smoke.
One comment must be made at this point in the story. The 3700 No. 910 raise was part of the mine ventilation sstem. There was no air movement through it. What was not known then, and really could not have been known, was the presence of a fire at the 3400-09 intersection 300 feet above. Existing, small volume leakage of air through a ventilation bulkhead carried the first wisps of smoke from a fire in contact with the bulkhead. Two 150 h.p. fans upstream from the bulkhead pushed mine exhaust air through the intersection on its way out of the mine. There was a high pressure across the surface of the bulkhead. The exhaust flow would, if it could, have moved back to the intake side of the fans—a short circuit that would quickly become a reality. To give an idea of the pressure across the bulkhead, a very strong man would be unable to open a standard sized door if it were in the bulkhead.
The first smoke was small in volume, since it had to either leak through the bulkhead (the fire may have started behind the bulkhead) or be carried by air that leaked through the bulkhead. Minutes later, the bulkhead, weakened by combustion, collapsed with a loud explosion. Tony Sabala heard the explosion at his work station. Quickly thereafter, a small doorway neart, blew open and a cloud of thick, black smoke boiled through the opening "like a tornado." Tony, Don Beehner, and Greg Dionne walked together to No. 10 shaft through a drift that was not part of the ventilation circuit. Passing through a ventilation control door, they found the No. 10 shaft station filled with dense smoke.
The heavy flow of deadly smoke came quickly, erupting out of the 910 raise and thoroughly contaminating the ventilation air supply for the No. 10 shaft. Within minutes of the first wisps of smoke, the deadly cloud arrived.
The 3400-09 bulkhead was constructed of plywood over mine timbers and coated with a layer of "non-burning" and "self-extinguishing" rigid polyurethane foam. Subsequent testing showed the product would burn fiercely and generate thick, black smoke. One source described it as similar to "solid gasoline." The polyurethane foam, plywood, and mine timbers that made up the bulkhead became an inferno. Tests of a replica to the 3400-09 bulkhead, constructed in a test mine near Buxton England in 1976, produced carbon monoxide ranging from 3% to 7% and reduced oxygen cyclically to a low of less than 1%. Combustion temperatures exceeded 2,500°F.
Not one person was hoisted with the No. 10 Chippy hoist. Don Wood, the hoistman, quickly succumbed to the first wave of deadly smoke. Other personnel on the 3700 level upwind of the 910 raise made their way to the Jewell shaft. Roberto Diaz, a service train operator, came from the direction of the Jewelt shaft and entered the smoke in a rescue attempt. He lost his life in that effort.
To understand the escape of personnel up the No. 10 shaft to the 3100 level, one must know another key element of the short-circuited mine fire ventilation system. Smoke from the fire at the 3400-09 intersection had to travel only 300 feet through the mined out 09 vein structure to reach the 3700 intake airway and thence flow into the No. 10 shaft where most of the men were working. A much longer path below the 3700 level, but still in the 09 vein structure, carried smoke down to the 4000 level and then westward to the No. 5 shaft and up to the 3700 level where it joined the main intake ventilation air supply to the No. 10 shaft. It was this delayed cloud of smoke that trapped Roberto Diaz as he attempted to return toward the Jewell shaft.
While most of the smoke flowing up the No. 5 shaft joined the air currents moving to No. 10 shaft, a small amount found its way upward to the 3100 level where it then moved to No. 10 shaft, quickly bringing escape from that location by unprotected personnel to an end.
There was a significant lapse of time between the arrival of dense smoke to the 3700 No. 10 shaft station and the 3100 No. 10 station. During that time, personnel including Don Beehner, Tony Sabala, and Les Mossburgh were able to escape to the Jewell shaft. Las Mossburgh worked in a repair shop adjacent to the 3700 No. 10 shaft station. He was on one of the first cage loads of men hoisted to the 3100 level. Some months later, I talked with Les about his exit across the 3100 level. "What was it like? What, if anything did you see?"
Unlike the dense, black smoke on 3700 level, the 3100 level had only a light haze of smoke. As Les walked across the 3100 level, he passed through mined-out segments of the Sunshine vein. Wisps of smoke were emanating from the gob-filled stopes below the level. We now know this leakage came from the 3400 exhaust airway. Les was out of the smoke before the dense short-circuited smoke made its way from the site of the fire, through the 09 vein on 4000 level, and up No. 5 shaft and adjoining raises to the 3100 level.
As mentioned earlier in this article, the path followed by recirculated smoke and gases to the 3700 level was short and the velocity of the air current rapid. The same was true for movement of smoke to the 4000 level, out to the No. 5 shaft (nearly half way to the Jewell) and up to the 3700 main drift which also was the main intake airway. The inundation of the 3700 level and the No. 10 shaft below that level was quick and deadly. The small split of air flow up to the 3100 level was very slow and much smaller in volume than that which entered the 3700 level. Nevertheless, once it reached the 3100 level and moved eastward to the No. 10 shaft and hoist room, it was quickly fatal.
Mention must now be made of the personnel involved in operating the No. 10 hoist and its conveyances. Ira Sliger was the hoistman on duty. Ira was an older hoistman and had some medical problems which interfered with breathing. Knowing that fact, Bob Scanlan, also a trained hoistman, ordered Ira to get out of the smoke. Ira left the mine by way of the 3100 Jewell shaft station. Bob Scanlan stayed on duty until he collapsed. Doug Wiederrick then took over the hoistman's duties until he also died.
Byron Schultz was the No. 10 double drum cager on duty that day. Greg Dionne, although not working as a cager .at the time of the fire, was skilled in such duties and volunteered to help Byron Greg, together with Tony Sabala and Don Beehner, had traveled from the 3700 level No. 8 pipe to No. 10 shaft and were hoisted to the 3100 level. Tony and Don proceeded to the 3100 Jewell shaft station, while Greg stayed behind and teamed up with Byron Schultz to form the usual two-man crew for hoisting personnel. According to statement from survivors, Byron stayed on the 3100 level, unloading personnel. Greg traveled on the conveyance to various stations in the lower part of the mine and assisted men onto the cage for hoisting. He also brought extra self rescuers on the cage and helped personnel put them on. In doing so, Greg had to remove the self rescuer from his mouth so he could talk to those he was helping, thus exposing himself to deadly carbon monoxide. Greg stayed on duty until he perished.
One more account of assisted escape from the fire, made possible by men who were themselves caught in the fire, remains to be told. Ron Florey and Tom Wilkinson were working in a stope below the 4800 level on the "west Side". As they attempted to make their way to No. 10 shaft, Tom lost consciousness. Ron was attempting to help Tom when Richard Allison and Ronald Wilson, drift miners working in the 4800 West Lateral came on the scene. Recognizing the problem, they assisted Ron and Tom into the 4800 West Lateral where there was smoke-free ventilation air supplied though a boreh that connected the 4800 level to the 3700 level. Allison and Wilson ventured into the smoke-filled area near No. 10 shaft advising Florey and Wilkinson they would bring some more men back to the "good air" zone. They perished in that attempt.
Last week's story summarized efforts to escape from the Sunshine Mine fire. It also included accounts of heroism as people helped one another, and even more heroic decisions by hoist personnel, Inotormen, and supervisors to stay on duty. The story concluded with the final hoisting of personnel from the working levels up No. 10 shaft to the 3100 level — their last possible route of exit. Unfortunately, the ventilation air on 3100 level had also become irrespirable. None of the personnel hoisted on the last three trips survived.
The scene now shifts to rescue attempts from outside the mine. Top management personnel were at a stockholders meeting in Coeur d'Alene and unavailable to respond to the fire. It was only by a quirk of fate that I was topside to answer a call for help. I will now recount my activities on May 2, 1972.
As Safety Engineer, I spent the morning touring the development activities on 5600 and 5400 levels. Jim Salyer, the development supervisor, and I traveled together. I concluded my inspection and training activities and made an early return to the surface. A pending safety committee meeting on Friday of that week required revisions to the Safety Rules Book. Had that not been on the agenda, I would have stayed in the mine until after 12:00 noon.
That is the quirk of fate I referred to above—an early departure from the mine. Leaving early involved walking to the Jewell Shaft on 3700 level, so I walked directly under the 3700-910 raise—the major pathway of smoke into the 3700 level about one-half hour later. There was nothing going on that might have given warning of a fire. Everything was "normal."
My time on the surface was short. I showered and dressed, entered my office and opened my dinner bucket, only to be interrupted by a frantic phone call from Tom Harrah, Shop Foreman. "Meet me in front of the warehouse right now! brought me running down a flight of stairs and out into the mine yard. Tom said, "There's a fire in the mine and they want you to dump the stench (fire warning system) and bring the helmets (McCaa mine rescue apparatus) to 10 Shaft on 3100 level." Tom walked with me to the compressor room where I activated the stench warning system. I then instructed surface personnel to take the ten McCaa units into the mine while I put on my mine boots, hard hat and other equipment. As I crossed the mine yard, I looked toward the Sunshine Tunnel where the mine exhaust discharged. Thick black smoke boiled Out of the opening. A chilling thought went through my mind; "I hope no one is downwind from that fire!"
I arrived at the 3100 level Jewell shaft station shortly before Al Smith and his mine train arrived from No. 10 shaft, pulling two muck cars loaded with men. Some of the men on the station waiting to be hoisted were mine rescue personnel. One of them asked, "Where are you going with the helmets?" I told them of the request to deliver them to No. 10 shaft. Mine rescue personnel Don Beehner, Hawkins, and Jim Zingler insisted on joining up with me to deliver the equipment to No. 10 shaft. The four of us formed a makeshift mine rescue crew. I was in charge. Having been warned about very heavy smoke "back past the timber station." we put on our breathing apparatus before entering that area. We proceeded toward No. 10 shaft. I was in the lead muck car. Larrs' Hawkins was operating the locomotive. Jim Zingler was riding on the back end of the locomotive, while Don Beehner rode on a timber truck pulled behind the locomotive.
As we entered the heavy smoke, visibility was limited to about five feet. The smoke reminded me of the old steam locomotives. Shortly after we entering the smoke, we encountered Roger Findley. Jim Zingler volunteered to take Roger out of the smoke. Our "team" was now down to three. I sampled the carbon monoxide concentration in the mine atmosphere with a Draeger gas detector, while observing a flame safety lamp to determine adequacy of oxygen. I was amazed to find carbon monoxide far above the range of the test tube. The tube had a range of 10 to 3,000 ppm, indicated on a scale by a dark stain in the chemical. The tube turned totally black before one-fourth of the sample had passed through. I knew the environment was lethal. I had to warn the other members of the team.
When I turned toward Larry to give a stop signal with my cap lamp, my face mask moved enough to allow a small amount of smoke into the mask. That was scary! Larry stopped the train. I told him the CO was very high. I reminded him of the need to make certain his face mask was tight and to "blow off" through the saliva trap valve every fifteen minutes, Larry passed the information to Don. We then proceeded slowly into the smoke, ultimately meeting Byron Schultz attempting to make his way out. I signaled Larry to stop the train. Byron was gasping for breath through a self-rescuer, and was in a state of near coUapse. Larry and I decided to "clear" a McCaa and put it on him. As we prepared the McCaa, Don Beehner removed his face mask, extended it toward Byron and said, "Here, use this. It's oxygen." In a matter of seconds, Don collapsed. Larry and I finished putting the McCaa on Byron and loaded him onto the timber truck—not a good place to ride, but there was no alternative. Then we directed our attention to Don, only to be thwarted by a malfunction to Larry's McCaa. Larry said, "I can't get any air!" I responded, "Hit your bypass!" Larry said, "I did; it didn't work; I have to get out of here!"
Larry then began walking toward the Jewell shaft station. I was alone, With the facepiece of the McCaa in place, Byron was able to talk He stated over and over, "They're all dead back there!" I knew then that I had to abandon the effort to reach No. 10 shaft. I attempted to lift Don Bechner into the muck car, but was unable to do so. I had no choice but to leave him.
Proceeding slowly through the smoke, I made my way out. After a short time, I saw a halo of light from Lariy's cap lamp and flashed the headlight on the locomotive, signaling him to step aside. As I passed Larry, I told him to climb onto the end of the muck car. We proceeded to the Jewell Shaft and were hoisted to the surface. We walked out from the Jewell shaft into a mine already starting to fill with people.
Out of the myriad of questions directed to me about the fire, one came to the top of the list. Where and how can a rescue effort begin? What should we ti-v to do next? Knowing the severity of conditions on the 3100 level, the logical next move was to try to reach No. 10 shaft on the 3700 level.
George Clapp, Bill Crouch, Stan Taylor and Ken Tucker joined me for a reconnaissance of the 3700 level. All was well until we arrived at No. 5 shaft. A torrent of dense dark smoke boiled up out of the shaft onto the station and was carried by the intake air current eastward to No. 10 shaft. A quick check for carbon monoxide indicated a concentration similar to that encountered earlier on 3100 level. I was convinced then that no one could survive in that environment without respiratory protection. Still, hope lived on: miners know how to barricade against fires. They also know how to use compressed air to keep a work heading ventilated.
Bill, George, and Ken entered the smoke for a closer look at what was happening. After locating a number of bodies, they returned to the fresh air base. There would be no more miners rescued on May 2. It would be a week before the last two survivors were found.
Now it seems appropriate to express a few thoughts about heroic deeds. A disaster often produces heroes. The Sunshine Mine fire produced two—the men who descended through a bore hole from the 3700 level to the 4800 level and rescued Ron Florev and Tom Wilkinson. They were in fresh air all the way. Their feat drew little attention from the mine rescue crews hard at work containing the fire and extending the search for survivors deeper and deeper into the mine. What hazards did the rescue teams face? Following are a few examples.
A mine rescue team made its way across 3400 level to the 09 intersection where the fire started. When they returned a day later, their path was blocked by a total cave-in at 08 intersection. Had that cave-in occurred the day before while they were at 09 intersection., they would all have perished—trapped between a raging fire and a pile of rubble that would take days to dig through.
A similar cave-in occurred at 910 raise on 3700 level. A mine rescue team traveled to a substation between 910 raise and No. 10 shaft. Their mission was to shut off electrical power to the mine exhaust fans on 3400 level. Accomplishing that task, they moved back toward the Jewell shaft, again passing under 910 raise. Minutes later, a huge cave-in occurred, completely blocking the drift, breaking the main 12" diameter compressed air line, and severing the 13,800 volt power line supplying the Strand substation—also the power source for the main No. 10 hoist on 3100 level. The cave-in also broke the main pump discharge line from No. 10 shaft to the Jewell. With no power supply to the pumps, flooding of No. 10 shaft began.
Yes, mine rescue work can be dangerous, but such dangers are not limited to mine fire situations. Many heroic deeds have taken place in other rescue activities. Mine workers enter the scene of rockbursts and dig with their hands to rescue those who are trapped, as Dan Meyer and Don Capparelli know. They retrieve fellow workers from cave-ins. Hundreds of such rescues have taken place in the Coeur d' Alene Mining District. To the men and women who labor in the mines, it is taken for granted. Rescues are not made in a quest for fame or honor. They are simply an expression of the bond between workers, a bond that adds to the pride of being a miner.
Deeds of heroism are by no means limited to miners. Firemen enter burning buildings in search of people trapped inside. Ambulance crews rescue injured people from vehicles surrounded by spilled gasoline or diesel fuel, knowing that a fire or explosion could occur at any time, or that unthinking passers-by might run over them with their vehicles. Police officers respond to calls for help in which they sometimes face deranged or suicidal people armed with all types of weapons. It all comes down to a common denominator. When a crisis occurs, real men and women respond. Don Beehner was a real man.
During the investigation of the fire, I learned about Don's earlier response to the fire. As he rode up to the 3100 level at No. 10 shaft, a fellow employee who had come from a lower level in the: mine started to collapse from smoke inhalation. Don removed the self-rescuer from his own mouth and gave it to the other person. He escaped the peril and was at the 3100 Jewell shaft station, waiting to be hoisted, when I arrived with the rescue apparatus. Rather than leaving, Don insisted on returning to a lethal environment in an attempt to help others. As stated earlier in this story, his second attempt to share his breathing supply proved fatal. Acts of heroism sometimes end that way, but they are not forgotten.
By late afternoon on May 2, operations personnel faced a shocking reality. Scarcely half the crew on duty in the mine had been accounted for. Both routes of access to the No. 10 shafl—3 100 and 3700 levels—were filled with smoke and lethal combustion gases. The only way of escape from the fire zone was by way of No. 10 shaft. The only way rescue personnel could reach personnel trapped in the fire zone was by way of No. 10 shaft.
There was a air of urgency in the search for survivors. One could only guess bow bad things might be down below the 4000 level where most of the men were working. Each passing minute of exposure to smoke and gases reduced the likelihood of survival. Reaching those personnel could only be done by mine rescue personnel. The mine rescue apparatus allowed a maximum use of two hours. Judicious use dictated 40 minutes into a rescue attempt before turning back toward the fresh air base. With the fresh air base on the surface and the No. 10 main hoist 8.000 feet away, time constraints made rescue through No.
10 shaft impossible without a fresh air base closer to No. 10 shaft. Fresh air ventilation to one of the hoists at No. 10 shaft had to be reestablished!
Requirements for specialized personnel and rescue equipment were enormous. Most of the mine rescue personnel from Sunshine Mine were among the missing, together with many key supervisory personnel. The task was enormous. True to the traditions of the mining industry, help arrived quickly. Between May 2 and June 1, 292 men and women arrived at the Sunshine Mine to assist in rescue and fire fighting activities. That number included 119 from the U. S. Bureau of Mines, 106 mine rescue personnel. 35 mining and support industry officials, and 32 attorneys and other officials taking depositions. In addition to personnel, self-contained breathing apparatus was needed. Teams from outside the district had to leave enough equipment to protect the mines they represented. Even the U. S. Air Force played a role, bringing twenty new liquid oxygen apparatus from England. Rescue attempts could begin. The teams were ready. Support activities were in place.
Is there another was to get to No. 10 shaft? Attention quickly turned to the Silver Summit Mine, an adjoining and connected mine that would serve as an emergency escapeway should the Jewell shaft become unusable. The decision was made to send a mine rescue team through the Silver Summit Mine and, if possible, to the No. 10 hoist on the 3100 level. The 3000 level of the Silver Summit Mine extended over the Sunshine Mine's 3100 level. An 85 foot inclined ladderway connected the two levels.
Mine rescue personnel took up the task. Air in the Silver Summit Mine was good until the team reached the Silver Dollar vent raise. That vent raise was the main exhaust for the Silver Summit Mine. It also served as a small volume exhaust airway for the Sunshine Mine. To reach the 3100 level of the Sunshine Mine and the No. 10 hoist would require traveling more than 2,000 feet through an irrespirable environment. Based on that reality, rescue efforts were refocused on the Sunshine Mine 3100 level.
Before addressing the 3400 level main exhaust fans, it must be stated that no one knew what was going on in the interior of the Sunshine Mine. No one knew that the 3400-09 intersection bulkhead had failed. No one knew of the resultant short circuit in the mine ventilation—the reality that the exhaust fans, instead of pushing the smoke and gases out of the mine, were instead pushing the deadly mixture back into the intake air supply.
So . . . how did the 3400 level exhaust fans come into consideration? Mine rescue teams were building seals at various locations along the 3100 level. The seals were essential to establishing a ventilation air circuit to the No. 10 hoist. The high ventilation pressure differential induced by the two 150 h.p. fans on the 3400 level made construction of air-tight seals very difficult.
Engineers advising decisions of operatIons management identified the problem created by the fans, however, management personnel familiar with basic mine rescue principles were aware of a cardinal rule in mine fires: you don't change ventilation unless you know where missing personnel are located and how the change would affect them. After agonizing over the decision for many hours, the decision was made to stop the 3400 level exhaust fans. A mine rescue team went to the 3700 Level F-19 substation and killed the power to the fans. This brought dramatic changes to conditions on the 3100 and 3700 levels. The fans were stopped at 3:06 p.m. on May 7 (USBM Final Report.) "By 4 p.m., ventilation to the 3100 level . . . had improved considerably." (USBM Final Report). As seals and bulkheads were added, ventilation air quality across the 3100 level continued to improve. Some of the worst sections of drift were lined with burlap and coated with sprayed-in-place rigid polyurethane foam, forming an air-tight tunnel to carry fresh air to No. 10 shaft. (That use of polyurethane foam will be addressed later).
On May 9, ventilation was re-established to the No. 10 hoist on the 3100 level. Electrical and mechanical maintenance was completed. The search for survivors in the lower reaches of the niihe could now begin. Sadly, that search was limited to finding and recovering bodies.
The mine rescue personnel all deserve special mention. Their work was hard and hazardous. The search for survivors led only to disappointment. Ultimately they would bring 91 bodies Out of the mine. Two of the mine rescue team members, in my opinion, deserve special recognition. Hecla's Art Brown and Bunker Hill's Harry Cougher worked day after day on their teams, not as management personnel on their way up the ladder, but as team members, doing whatever was assigned to them. They led by example. They are part of today's top management with Hecla and Sunshine.
Another mine rescue team member from the Sullivan Mine in Kimberly, B.C., Jack Walsh, returned to become Director In Charge of the Coeur d'Alene Mining District Central Mine Rescue Unit (CMR).
There were many mining management personnel who worked day after day to keep the mine rescue teams supplied with properly maintained equipment. Bill Calhoun, then President of Day Mines, took charge of the bench technicians activities. When rescue and recovery activities at the Sunshine Mine were finally ended, Bill stayed on with CMR and played a key role in upgrading mine rescue techniques and training to the level it now maintains today.
(A note to the readers: Documents in my possession, in combination with my own observations, leave a gaping hole in the story of May 2,1972. I also acknowledge that some of the information I have may be incorrect, If any of you have information to offer, or if you have questions, feel free to phone me at 682-2320 (Bob Launhardt).
As I contemplate the twenty-five years si that horrible day in May, 1972, the sadness of the loss is at times nearly unbearable. The 91 who died were all personal acquaintances. Many were long time friends. Adding to the feeling of sadness is an even greater frustration, at times leading to outbursts of anger, over my inability to communicate to the rest of the mining industry one of the most crucial lessons from the fire—the deadly effects of rigid polyurethane foam as an accelerant to what would otherwise have been another "normal" hardrock mine fire. Had that reality been recognized through the post-fire investigation and then publicized, the loss of 177 miners in the Kinross gold mine in 1986 might have been prevented. That disaster also involved polyurethane foam. I am still haunted by the memory of a taped interview with the Kinross mine manager that I heard during a radio newscast. Twice during the interview, the mine manager lamented, "They told us it wouldn't burn!" That's the same thing they told us at Sunshine Mine in the early 1960's when polyurethane foam was applied as a ventilation airway sealant on 3100, 3400, and 3700 levels.
Before moving ahead with the Sunshine fire narrative, I wish to provide information, quoted from published documents, that may help the reader understand the pre May 2, 1972 mind-set of the hardrock mining industry regarding mine fires. Read the quotations and form 'our own opinions, if you are interested in reading more from articles quoted, please contact me.
From Deep Mining by J. Spaulding - London Mining Publications, 1949: "Where the atmosphere is saturated and the timber always wet and in mines where the timber decays rapidly, not only is the risk of fire breaking out much less, but also, should a fire occur, its rate of spread is very much slower, so that it is proportionately easier to overcome." (The Sunshine Mine, together with all the deep mines in the Silver Valley is basically wet. The atmosphere is saturated. Exhaust airways are actually super-saturated. Timbers decay rapidly.)
From Fire Prevention al Noranda Mines by H. C. Bent - 1957 Canadian Mining Journal: "It is my opinion and the opinion of others familiar with the (Noranda) mine, that we could never have a fire underground where we would meet with a deficiency of oxygen in the air, or a dangerous concentration of carbon monoxide."
From KJ FIRE COLD - Mining & Quarrying, August 1962: "A revolutionary method of insulating and sealing passageways in coal and metal mines by applying sprayed-in-place urethane foam to exposed underground surfaces was demonstrated by the U. S. Bureau of Mines for the American Mining Congress in Pittsburgh on May 10...Since the foam will not support combustion it can be used to insulate combustible materials in the mine and makes possible the quick erection of emergency, flame-retardant curtain walls to localize an outbreak of fire underground. As a result of this research, rigid urethane foam has been applied on roof, ribs, and stoppings in more than 200 mines to minimize spalling and reduce air leakage through ventilation controls."
From an official USBM publication titled FIRE HAZARDS OF URETHANE FOAM IN MINES - RI 6837, published in 1966: "After 2 years of research on sealants and coatings, the Bureau of Mines published a report n urethane foam. Fire hazard from foam exists if flame propagates beyond the ignition source or penetrates the foam. Foam on the ribs and adjoining roof presents a fire hazard. Flame propagated in all tests with foam on the ribs and across the roof. Figure 15 shows the dense smoke produced during one of the tests."
Allow me to digress briefly from the business of quotations and offer a few comments. The USBM's knowledge of fire hazards of polyurethane foam changed considerably between 1962 and 1966. Accordingly, three questions must be asked about the polyurethane foam in the Sunshine Mine. First, did the USBM know where and how it was used on the 3400 level prior to the May, 1972 fire? Absolutely yes! Engineers from the Denver Technical Support group completed a ventilation survey, including the 3400 exhaust airway, in the fall of 1971. The foamed bulkhead was specifically mentioned in the report, including data on the amount of exhaust air leaking through the bulkhead. A follow-up survey by USBM was completed on April 16, 1972, two weeks before the fire.
Second, how could the USBM ignore rib and roof applications of polyurethane foam in critical locations within the Sunshine Mine in 1972 when the hazards were well documented six years earlier? Finally, how could the USBM — 119 strong during their first month of control over the mine following the fire, allow installation of hundreds of square feet of polyurethane foam in a continuous rib and roof application, while a raging fire was advancing on the area of installation? I honestly believe the people in the field had never seen RI 6837.
From POLYURETHANE FOAM FIRE HAZARD IN MINES by D. O. Wilde, B.Sc., SMRI as published in the Colliery Guardian, August 1968: "The fire resistance of polyurethane foam depends, to some extent, on the proportions of the constituents in the final compound and on the density of the foam. Fire resistance decreases as density decreases, so that low density foams, such as are used in mines, tend to have a low fire resistance. The fire resistance can be improved by the use of a flame retarding agent, but the proportion of the agent must be limited if the foam is to be mechanically acceptable so that, despite the agent, polyurethane foam remains a highly flammable material and one with a very low fire resistance."
From Kinross—An Early Reflection, London, October 3, 1986 as printed in the MINING Journal: "The underground fire which occurred at the Kinross gold mine in the Evander district of the Transvaal two weeks ago was a tragedy for the 177 victims. An oxy -acetylene cutting torch on a main haulageway ignited a polyurethane based foam which had been used in the haulagewav as a water-seal. The fire itself was extinguished relatively quickly as relatively little other inflammable material was involved. However, the foam which did catch fire produced toxic fumes in the main intake airway carried into the mine workings at the start of the day shift when the maximum number of workers would be underground." That short duration fire brought quick death to 177 miners downwind.
Quite obviously, the May 2, 1972 Sunshine Mine Fire was no ordinary fire, and would thus require an extraordinary investigation. The investigation began in earnest when the fire was officially declared extinguished and continued until January of 1978 when a trial over liability began in Boise. The investigative team included representatives of the USBM, Idaho State Office of Mine Inspector, Sunshine Mining Company, and a representative of USWA Local 5089. The team was from time to time joined by attorneys representing interested parties.
TV coverage assessed blame long before on-site investigation began. As fate would have it, Ralph Nader was in Spokane at the time of the fire, and quickly determined the cause of the disaster—a callous disregard for safety by Sunshine Mining Company. J. Davitt McAteer, one of "Nader's Raiders" and now Assistant Secretary of Labor for Mine Safety and Heal& was assigned to duty at the mine. I spent many hours with him, providing detailed information in the hope that facts would bring the investigative reporting closer to reality. Unfortunately, facts that did not support the main story line got very little press coverage. It was not until after the fire was out that opinions about the cause of the disaster were based on objective findings. Those findings provided a framework for developing plans to reopen the mine. Those findings also resulted in changes in the entire mining industry. One major change was the mandatory use of self-rescuers in all U. S. mines. The Mine Safety and Health Act of 1977 was another offspring of the disaster.
To put it mildly, I was very disappointed with the early activities of the investigative team. The focus was on how the fire started, not on what caused the fire to become a disaster. Remember the quotes from industry leaders! The Sunshine Mine Fire was a disaster that could not occur in the hardrock mining industry. Hardrock fire disasters only occurred when fires burned in shafts or ventilation raises. By the time the investigation began, the majority of personnel active in rescue and recovery had reached a similar conclusion: this was no ordinary mine firel Logic demanded identification of the extra-ordinary factors, but that task would have to wait. In its own "Final Report" the USBM stated, "...the fire increased in intensity, spread more rapidly, and produced more toxic gases than is considered normal for underground mine fires." That undisputed observation should have, in my opinion, driven the investigation. As it turned out, the USBM's focus was on how the fire started and how shortcomings in mine design and safety program contributed to the loss of 91 lives. The phenomena just quoted from the "Final Report" received little attention.
To have a fire, one must have fuel, air (oxygen) and sufficient heat to initiate combustioi of the fuel-air mixture. The investigators quickly reached a consensus that the fire began at or near the 3400-09 ventilation bulkhead. Combustible material in the fire zone included a bulkhead constructed of timber and plywood and coated with rigid polyurethane foam, located in a mined-out area containing significant amounts of timber used for ground support and passageways.
What about the air supply? I inspected the old workings behind the 3400-09 bulkhead in the same way that other old workings were occasionally inspected. Field tests for oxygen indicated normal and adequate oxygen levels. Although nominally sealed off from active workings, the fire zone was ventilated by leakage out of the exhaust airway. The USBM "Final Report" acknowledged 2.000 cfm leaking into the fire zone as measured on April 24, 1972. Although not a huge volume of air, it was more than adequate to prevent an oxygen deficiency. With fuel and adequate oxygen, the fire triangle needed only an ignition source.
It was quickly established that the initial fire zone did not contain energized electrical conductors. Thus, that frequent source of ignition in mine fires was ruled out. Smoking on the 3400 level in the exhaust airway was not only prohibited but next to impossible due to the high velocity of the exhaust airflow. Consensus ruled out smoking as a source of ignition. Cutting and welding did take place on the 3400 level on the day of the fire, but it was done about 340 feet downwind of the 3400-09 intersection, so that potential source of ignition was ruled out by the investigating team.
Attention then turned to arson. Samples of soot and ash and other fire residues were collected from numerous points in the fire zone. Experts analyzed the samples, searching for residues of substances known to be used in incendiary devices. The search included residues of explosives used in the mine, since explosives can be ignited and will produce a very hot fire. Finally, identification of a possible arsonist had to be made. What follows is admittedly hearsay. I heard it from attorneys involved in the investigation. It was shared after law enforcement personnel had concluded their investigation.
Who might have carried a serious grudge against the Company? There was a miner—I will call him Ben—who had a heated disagreement with senior mine supervisors about earnings. He openly threatened to "get even" with the Company. Fellow employees were aware of his threats. Ben died in the fire, but his widow allegedly raised some questions about his possible involvement. Ben had an identical twin brother who visited the Silver Valley from time to time. The widow believes it was the evil twin. "Bad Ben." who set the fire and then left the area, never to return.
There were other suspects. Law enforcement personnel converged on their residence, only to learn that the occupants had moved out during the previous night. Allegedly some remnants of possible incendiary devices were found in the basemcni of the house.
Well, so much for hearsay! Why bother with writing about it? Consider what the USBM required in response to the possibility of arson. Faced with the possibility that the arsonist may have survived the fire and could be among employees returning to the mine afler it reopened. Sunshine Mine was required to prevent access to inactive areas in the mine through use of strong bulkheads or substantial doors secured with heavy chains and padlocks! Why? Because of rumors suggesting how the arsonist started the fire.
The arsonist supposedly made his way from No. 10 shaft into the area where the fire started and planted an incendiary device. Or he may even have climbed one of the manways to the 3400 level, and placed the device, fitted with a timer, near the 3400-09 bulkhead. A similar deed could be repeated. Based on that possibility, access to all inactive areas of the mine was rigidly controlled. Chains and padlocks were in place!
One of the reasons for writing this story is to share knowledge gained from investigating the Sunshine fire that could, if used wisely, prevent similar mine disasters. Such knowledge also may be of benefit to the public sector. Lesson No. 1 involves the disastrous short-circuit in the mine ventilation system, caused by the fire-related failure of the ventilation control bulkhead at 34.00-09 that separated the exhaust airway from old workings that were connected to both intake airways. Proper design of the mine ventilation system would have prevented the May 2 disaster. To understand the lesson, one must understand the basic design of the system.
Intake (fresh) air entered the mine from the surface through the Jewell Shaft, was carried about one mile eastward to No. 10 Shaft across the 3100 level and 3700 level, and down the shaft to the working levels. Ventilation air to each working area was controlled through use of ventilation doors and booster fans. Most of the intake airflow crossed the 3700 level.
Exhaust (used) air flowed through a series of ventilation raises up to the 3400 level main exhaust airway. It then moved in a westerly direction until it turned upward into No. 3 Shaft to the 1900 level, up the Incline Shaft and out of the mine. Picture in your mind's eye the 3100 and 3700 level intake airflow moving east to No. 10 Shaft and the 3400 level exhaust airflow moving west for several thousand feet half way between the two intake airways. Envision the exhaust air constantly searching for a way to break through to the lower pressure of the two intake airways where it could then find its way back to the intake side of the fans. That's the path of least resistance. That "picture" will help you understand the following analogy.
The fatal flaw in the ventilation system involved the location of two 150 h.p. ventilation fans upstream from the 09 ventilation control bulkhead. The two fans, operating in series, developed a tremendous pressure between the exhaust airway and the rest of the mine. To illustrate the amount of force, no one person could open a standard size door against such pressure.
The incipient mine fire quickly turned into a holocaust when the :3400-09 bulkhead, weakened by the fire, collapsed. The full force of 300 h.p. drove wood and polyurethane smoke and gases through the mined-out 09 vein structure, down a series of nianways to the 4000 level, west to No. 5 Shaft and upward to the main intake airway on 3700 level. The smoke quickly inundated No. 10 Shaft and the production areas of the mine where the majority of the men were working. The exhaust airflow upward to the 3400 fans was then boosted back through the fire zone. That deadly short-circuit continued for several days.
A mine ventilation system must be designed to prevent any serious recirculation or short-circuiting of exhaust airflow into intake airways. This can be achieved through judicious placement of ventilation fans and use of non- combustible ventilation bulkheads. Had the ventilation fans on the 3400 level been located downstream from the 3400-09 ventilation bulkhead, most of the smoke from the May 2 fire would have been exhausted harmlessly to the surface. Only the relatively small volume of leakage into the two intake airways would have put smoke into the active areas of the mine. It's that simple! I find it hard to understand how the USBM could fail to include that obvious finding in their listing of "major factors (that) contributed to the severity of the disaster." (USBM Final Report.)
For several years prior to the mine fire, Sunshine Mine operators struggled with upgrading the ventilation system to keep up with development work on the lower levels of No. 10 Shaft. USBM offered services of ventilation engineers from their Technical Support Group in Denver, Colorado. At Sunshine's request, USBM engineers spent several weeks in the fall of 1971 evaluating the mine ventilation system. Their written report recommended improvements including enlargement of restricted sections of the 3400 exhaust airway. That project was in progress on May 2, 1972. USBM engineers performed a follow-up visit to the mine in April 1972. The follow-up evaluation included measurements of air volume and leakage into old workings made on April 24, 1972, less than two weeks before the fire. The USBM ventilation experts knew all the details of Sunshine's ventilation system, including the potential for short-circuiting and the presence of polyurethane foam on the 3400-09 ventilation control bulkhead as well as on the 08 bulkhead, scarcely 100 feet upwind from 09. Had USBM investigators addressed these obvious (by hindsight) hazards, they would have had to implicate their own experts for failure to call attention to the hazards.
There are parallel hazards in the world above the surface of the earth. During the years following the Sunshine Mine fire, I learned of two fire disasters in hotels, one in Las Vegas and one in San Juan, Puerto Rico that occurred because of recirculalion of smoke and gases from a fire. Both buildings utilized a central heating, ventilation, and air conditioning (HVAC) system. In both cases, the fire as restricted to one relatively small area. Deaths occurred when the HVAC return air svsteni carried the smoke to the central unit and then, after either heating it or cooling it, distributed the smoke and gases throughout the entire building. They didn't call it a short-circuit, since the system was designed to recirculate. The entire interior of the building was included in a single ventilation loop.
Such a centralized system is cost-effective but, in my opinion, inherently dangerous. A fire anywhere in the building will ultimately spread smoke thoughout the building unless the central HVAC system is immediately shut down. For that reason, a hotel or motel with a heating and cooling unit in each room is much safer.
Fire safety in high rise buildings using central HVAC systems could be dramatically improved if two systems were used, each dedicated to one-hall of the building. Use of a fire door dividing the main corridor on each floor would prevent combustion products contaminating one system from entering the other system. Building occupants in the HVAC circuit affected by a fire would only have to pass through the fire door on their floor into the other side of the building to escape from smoke and gases.
In my opinion, the USBM "Final Report" failed to properly address the two most important safety deficiencies affecting the Sunshine Mine Fire—the potential for a short-circuit between the exhaust airway and the intake airways, and the fire hazard of using polyurethane foam to seal a critical ventilation control bulkhead,
(A copy of the "Final Report" entitled Health And Safety Report - Final Report Of Major Mine Fire Disaster - Sunshine Mine - Sunshine Mining Company - Kellogg., Shoshone County, Idaho - May 2, 1972 by Stanley M. Jarrett, E. Levi Brake, Robert E. Riley, and Roland V. Wilson should be available in local libraries.)
In combination, the two safety deficiencies turned a fire in an inactive part of the mine into a disaster that killed more than half the crew working at the time, It is inappropriate to rank the two factors, since either, by itself, would most likely not have resulted in a fire disaster. Without the short circuit, almost all the combustion products from the polyurethane foam- induced, fuel-rich fire would have gone harmlessly to the surface. Without the polyurethane foam, there would have been no accelerant to produce rapid combustion and the large volume of deadly smoke and gases.
But what about the high velocity airflow induced by the 3400 level ventilation fans? In excess of 90,000 cfm of exhaust air rushed through the nominal 6' x 8' airway. Wouldn't that whip up a big fire, even without the polyurethane foam? My experience says. "No!" Wood in the 3400-09 bulkhead included 4' x 8' sheets of ¾" plywood, 2" x 4" furring strips, 10" x I0 drift posts and 12" x12" or larger drift caps. Relative humidity was 100%. An accidental fire in that location and material ignited by such things as a tossed cigarette or a chunk of hot slag from a cutting torch was unlikely,
Rapid airflow past a small fire in material such as described above dissipates the heat and may even cause the fire to go out. For an example, I offer a summary of a 1974 fire in the Sunshine Mine. That fire occurred below the 2700 foot level in the Jewell Shaft—a four compartment wooden shaft. No one was working in the mine when the fire started. A 2,300 volt power cable shorted phase to phase and exploded into an extremely hot electric arc. The arcing continued for about 30 seconds before the safety switch controlling the circuit opened. The intense heat vaporized several feet of borehole power cable and ignited adjacent shaft timbers to which the cable was anchored. More than two hours elapsed before the fire was located. During that time, less than two pounds of wood burned and the fire had gone out. About 120,000 cfm of fresh and relatively dry air passing through the Jewell Shaft dissipated the heat.
What would have happened, however, if the shaft timbers had been coated with polyurethane foam? In my opinion, the fire would have exploded into a conflagration similar to May 2, 1972 or the Kinross gold mine fire in South Africa in 1986.
I must say as plainly as possible that, during the formal investigation of the fire, I had no knowledge of the fire hazard of polyurethane foam. I also am convinced that USBM Investigating Committee personnel Brake, Riley and Wilson shared in my ignorance, or they certainly would not have permitted use of that product in fire fighting activities. However, I strongly suspect that the higher echelons of the USBM were aware of USBM RI 6837 - Fire Hazard Of Urethane Foam in Mines, by Donald W. Mitchell, Edwin M. Murphy, and John Nags' - USD01, Bureau of Mines - 1966. Donald Mitchell was a key witness during the 1978 trial in Boise. The Story of his cross examination while on the witness stand will come later.
I now begin a point-by-point challenge of the "Final Report." Nine points are listed in the Abstract, pages 3 and 4. I will address them one at a time, beginning with the lead-in paragraph: "It is not possible to single out any one fact as the chief cause for the large loss of life. However, the Bureau of Mines believes that the following major factors contributed to the severity of the disaster:"
Factor No. 1
"The emergency escapeway system from the mine was not adequate for rapid evacuation."
In my opinion, no escape system from a deep, multi-level mine could have been adequate in a similar fire. "Rapid" is a relative term. Time for escape from the fire zone was severely limited by the unusually quick increase in toxic combustion products. Some of the mine personnel collapsed before they reached the No. 10 shaft station on their work level. The hoistman at 3700 level No. 10 personnel hoist quickly became sick to his stomach and was unable to hoist any personnel. He collapsed and died near the hoistroom.
Most of those who escaped across the 3700 level to the Jewell Shaft worked in areas outside the area inundated with smoke. Those first hoisted to 3100 level escaped to the Jewell Shaft before the heavy clouds of smoke entered that level. Of those subsequently hoisted, forty-three survived by wearing self-rescuers. Their names are listed rn the "Final Report" beginning on p. 94.
Factor No. 2
"Top mine officials were not at the mine on the day of the fire and no person had been designated as being in charge of the entire operation. Individual supervisors were reluctant to order immediate evacuation or to make a major decision such as stopping the 3400 level fans."
Had all top mine officials been gathered in my office when Tom Harrah relayed the message about the fire, it would have made no difference. Why? Any person who understands the basics of mine fire fighting and mine rescue knows with certainty that decisions cannot be made until fundamental information about the location of the fire and the status of the ventilation system is known. What could "top officials" have done that had not been done during the first hour on May 2?
Regarding stopping the 3400 level fans, it was not until 3:06 p.m. on May 7 that the 3400 level fans were stopped. Why? It took that long for the many "experts" gathered at the mine to gain some understanding of what was going on in the mine. Even then, the decision to stop the 3400 level fans was made with a great amount of anxiety. Remember a basic rule of mine fire fighting—you do not change ventilation unless you are certain what the results will be and also certain that the change will not adversely affect personnel in the mine.
Factor No. 3
"Company personnel delayed ordering evacuation of the mine for about 20 minutes while they searched for the fire."
I already addressed that issue in Partl, but will reiterate part of that story now. "The first challenge was to try to find the source of the smoke. Although the subject of severe criticism, it was a key factor in a choice that had to be made. Should the crew be sent out of the mine through the 3700 Jewell shaft station or up through No. 10 shaft to the 3100 level? If sent to the 3100 Level, should they then travel to the Jewell shaft or use the emergency escapeway through the adjoining Silver Summit mine? It would have been chaotic to begin an evacuation without first knowing the route to be followed."
Part VII concluded with my response to No. 3 in the list of what the USBM believed to be the "major factors" that contributed to the severity of the disaster. My review of the USBM analysis is not an attack on their report. That would serve no purpose. would be untimely, and would address a function no longer performed by the Department of the Interior. Rather, it is an essential step toward identifying and justifying safety improvements for today's mining industry. We continue with the list from their "Final Report."
Factor No. 4
"The series ventilation system used in the mine caused all persons inby the fire, which contaminated the main intake airways to be exposed to smoke and carbon monoxide." ("Inby" is a coal mining term and not used in the Coeur d' Alene Mining District.)
That statement is very misleading. It suggests that the "series ventilation system" routed exhaust back into the intake airways. The fire was not in an intake airway; it was in the exhaust airway. It was the short-circuit caused by the failure of the 3400-09 ventilation bulkhead that caused the disaster, not the fact it was a series ventilation system.
Factor No. 5
"Most of the underground employees had not been trained in the use of the provided self rescuers and had difficulty using them. Some self rescuers provided by the company had not been maintained in useable condition."
That statement still puts me into orbit. Self rescuers were not required in hardrock mines. To my knowledge, Sunshine Mine was the only active hardrock mine in the United States using them at the time of the fire. Properly maintained and stored self rescuers in adequate numbers were available throughout the working areas of the mine. All mine rescue personnel, first aid personnel, and supervisors were trained in how to use them. USBM should have complimented the company for having self rescuers rather than directing criticism for failure to carry the voluntary program farther. Their own "Final Report" includes the names and working places of 43 men who used self rescuers in their escape, 8 from within the fire zone on the 3700 level and 35 from the lower levels of No. 10 shaft.
Regarding the statement that, "Some self rescuers... had not been maintained in useable condition," I must tell you the full story. I placed self rescuers in the mine in 1963 because mine rescue training material convinced me it was a good idea. Bluntly stated, the majority of the mine crew thought it was a crazy idea and told me so. (Remember: The majority of the crew considered them useless in a hardrock mine!)
From July 1967 through February 1972, I was employed elsewhere. One serious problem I discovered upon my return to the mine was theft and destruction of self rescuers. To my dismay, I learned that some of the employees had taken self rescuers home because "they worked good for spray painting!" Many others had been opened out of curiosity—just to see what was inside. Once the seal was broken, moisture in the environment quickly turned the unit into rusty junk
I replaced dozens of self rescuers over a period of several months. Prior to May 2, all levels of the mine had been restocked with good units. Blaming the company for a problem created by a few employees, acting out of ignorance, serves no useful purpose.
Factor No. 6
"Mine survival training, including evacuation procedures, barricading, and hazards of gases, such as carbon monoxide had not been given mine employees."
Agreed! That type of training for all mine employees came to the industry after the Sunshine Fire. Such training, however, had been given to supervisors, mine rescue personnel, and first aid personnel in the Sunshine Mine. While hindsight suggests such training for everyone would have been beneficial, my experience with self rescuers — and "stuff for coal miners"—suggests how difficult it would have been to "sell" such a program to hardrock miners. Once again, remember, the attitude of the entire hardrock mining industry toward a fire disaster—"lt can't happen in a hardrock mine!"
Factor No. 7
"The emergencv fire plan developed b the company was not effective. The company had not conducted evacuation drills."
There is no evidence suggesting that any loss of life resulted from an ineffective emergency fire plan. Although evacuation drills had not been conducted. I am firmly convinced such drills would not have changed the outcome on May 2. The disaster developed too quickly. How might anyone have planned and conducted a drill to prepare for something that consensus said could not happen'?
Factor No, 8
"Abandoned areas of the mine had not been sealed to exclude contaminated air from entering the ventilation airstream."
Totally incorrect! All inactive areas were adequately isolated from active workings through the use of bulkheads. Four such bulkheads, including those at 3400-08 and 3400-09, were sealed with polyurethane foam. The polyurethane foam sealant was used to prevent leakage of contaminated exhaust air into the intake airstream.
Factor No, 9
"The controls built into the ventilation system did not allow the isolation of No, 10 Shaft and its hoist rooms and serrice raises or the compartmentalization of the mine. Smoke and gas from this fire was thus able to move unrestricted into almost all workings and travelways."
Very good 20/20 hindsight! It's a shame that the USBM ventilation experts didn't recommend such ventilation system controls subsequent to their 1971 full-mine ventilation survey. Yet, in fairness to USBM and the hardrock mining industry, one must recoguize and acknowledge the basic attitude of the industry prior to May 2.1972. Nothing similar to the Sunshine Mine Fire had occurred in the United States.
You have read the nine "major factors that contributed to the severity of the disaster" as listed by USBM. You have also read my responses. Does the USBM report provide a clear answer as to why '.,.the fire increased in intensity, spread more rapidly, and produced more toxic gases than is considered normal for underground mine fires?" (USBM Final Report on page 49) In my opinion, it fails to address the heart of the problem—why was the Sunshine Mine Fire so deadly?
USBM's report suggests that, "a fire smoldered in the abandoned area, filling it with smoke before the smoke as expelled and detected. The sudden release of a large volume of smoke and toxic gases was not characteristic of the normal growth of an open fire." (USBM Final Report on page 47) I fully agree the fire was not normal growth. However, the theory of a smoldering fire is without merit, Mv belief, for which I will offer solid arguments, is that polyurethane foam, acting as an accelerant, caused the uncharacteristic growth of the fire, I will also offer proof, using USBM's own ventilation data, that a smoldering fire, filling the abandoned area with smoke and gases, absolutely, could not have gone undetected. These issues will be addressed next week.
Deception With A Purpose
The "Final Report" on the Sunshine Mine Fire was released early in 1973. I must confess that I never respected the quality of research that it represents. Only recently did a believable reason for some of the absurdities stated in the report occur to me. Had the USBM issued an official report on the fire based upon what they knew about polyurethane foam's impact on fires, the would in effect have conceded pending litigation to the plaintiffs. Several lawsuits had been filed in behalf of widows, children, and families, seeking damages for wrongful death of the 91 victims. Claims were also filed to recover damages to the mine, loss of production and other related costs. The U.S. Government was among the defendants. The key issue in the litigation was the premise that, but for the combustion of rigid polyurethane foam at the 3400-09 intersection, the fire would not have been a disaster.
I must confess a feeling of deep disappointment in the possibility that the U.S. Government might have deliberately skewed the "final Report" because of pending litigation. Why the disappointment? Perhaps it reflects my naïveté toward matters of safety and health. While I accepted the reality that regulators and industry were frequently at odds over alleged safet and health issues. I expected full cooperation and honesty between regulators, labor, and industry when investigating accidents that resulted in serious injurv or death.
Now we address the fundamental issues in the litigation. What caused the fire? How did it start? Why did the fire increase in intensity, spread more rapidly, and produce more toxic gases than is considered normal for underground mine fires? Three questions—the first two are of little consequence. Fires occur in mines, much as they do in industry and commerce. Fire prevention is a common goal and worthy of due consideration. Fortunately, catastrophic fires in metal and non-metal mines. such as that in the Sunshine Mine on May 2, 1972, are virtually unknown. As of this writing, I am aware of only three similar disasters. The first catastrophic (27 lives lost) polyurethane foam fire occurred in England in a coal mine. Within a few years, that product was banned in the United Kingdom. The second, (91 lives lost), was at the Sunshine Mine In 1972. The third disaster (178 lives lost) occurred in the Kinross Gold Mine in South Africa in 1986.
Being unwilling, for obvious reasons, to acluiowledge that the quantity of polyurethane foam lining the ventilation airway at the 3400-09 intersection was more than adequate to accelerate combustion of the wooden bulkhead and surrounding timbers to a fuel-rich fire state, the USBM faced a serious challenge. How could they explain the huge cloud of dead1 smoke and gases that so rapidly inundated most of the active mine area? Somehow, an explanation must be found that could seem credible to a jury.
Knowing full well that a fire in a non-gassy hardrock mine involving mine timbers could not rapidly increase in mtensirv and generate huge amounts of smoke and gases, the theory of a smoldering fire was developed. The "Final Report suggests that, "a fire smoldered in the abandoned area, filling it with smoke before the smoke was expelled and detected. When the 09 vein bulkhead burned through, a large quantity of air reached the smoldering fire which then rapidly increased in intensity." if a fire had smoldered undetected for days or even weeks, as has been suggested in several reports, it might have been possible to develop a large volume of smoke and toxic gases.
The USBM faced another serious challenge. The fire did not start in a remote section of the mine, far removed from any active workings or work activities. Rather, the fire began between two intake airways and only 100 yards upwind from a ventilation improvement project. A crew was working on that project on May 2. A second crew also worked at the site hardly one hour before the conflagration. As any experienced miner can tell you, the human nose is one of the best smoke detectors available in the mines. Somehow, the USBM had to find a way to explain how a smoldering fire could indeed go undetected.
Allow me to digress for a bit. How big must a fire be to generate enough smoke to be detected by the sense of smell? Smoke from a cigar at the 3700 level Jewell station could soon be smelled at No. 10 shaft, nearly one mile away. One "mine fire" was traced to a mechanic using a cutting torch to remove a coupling from a pipeline. The smell of the scorched neoprene gasket in the coupling was detected throughout the west side of the mine downwind from the site. Smoke from a track tie scorched when a rail was cut with an acetylene torch on the 4800 level of No. 10 shaft was smelled by half the crew in the mine that day. It takes very little smoke in a mine to reach the threshold of smell.
The "Final Report" used USBM ventilation data to explain an undetected, smoldering fire. The following is quoted from item 5.. page 45: "The location of main fans on the 3400 level caused high positive pressure in exhaust airways and negative pressure in intake airways, thus creating a pressure differential betii'een the positive side of the fans and the 3100 and 3700 levels, however, the portion of the 3400 level exhaust airway inby the fans and the connected 3550 level was at a lower pressure than the intake air The normal leakage pattern prior to the fire was from the positive pressure side of the 3400 level fans and from the 3300 and 3700/eve/intake airstreams to the 3550 level and then toward the negative pressure side of the exhaust fans on 3400 level. This leakage pattern prevented smoke from entering the Intake airstream, where it would have been detected, until the fire caused a direct short circuit in the ventilation system,"
So far, so good! USBM now has a theoretical smoldering fire from which smoke leaks across the inactive 3550 level to the negative pressure side of the 3400 level fans and does not enter the intake airways. Nobody works on the 3550 level, so nobody will smell the smoke and sound an alarm. The smoldering fire, most probably caused by "spontaneous combustion of refuse near scrap timber used to backfill worked out stopes," was supplied with air o maintain the smoldering fire by "leakage through the 09 vein bulkhead." "A blast initiated on day shift May 1, 1972, to enlarge the exhaust air shaft 340 feet west of the 09 vein now have further loosened the bulkhead causing increased leakage of air."
Now the theoreticians have provided a larger air supply to explaiIi bigger fire. What a bunch of poppycock! While the theory does a fair job of explaining a buildup of smoke without it being detected, it falls flat on its face in explaining what happens to the smoke after it passes through the 3400 level fans.
The smoldering fire was fed by 2,000 cfm of air (Final Report, p. 45). That volume of air is more than adequate to move the smoke back to the intake side of the 3400 level fans. Joining the exhaust air stream, the smoke passed through the fans and, except for a small amount of leakage back into the smoldering fire, moved in a westerly direction along the exhaust airway toward the surface. Had that smoky air all exhausted to the surface, the USBM theory would have been sound—except for the crews working on 3400 level on May 2.
However, there was significant leakage from the 3400 level exhaust, downstream from the 3400 fans, into the 3700 and 3100 level intake airways. smoke would have been smelled in both intake airways. How significant was the leakage?
Significant enough that sections of the 3700 and 3100 level intake airways were lined with plywood and sealed v polyurethane foam to minimize the leakage. Did the USBM know about the leakage? Absolutely! As a matter of fact, the first place polyurethane foam was applied in the Sunshine Mine was on the 3100 level. It was a demonstration of the product arranged by a USBM engineer. I was present when the work was done.
Before proceeding. I want to apologize for the complexity of last week article. Most of the people involved in investigating the fire never understood the ventilation circuits that carried the smoke and gases throughout the fire zone, nor were they aware of how large-scale applications of polyurethane foam (PUF) could affect combustion. Without that knowledge, the disaster resulting from the Sunshine Fire remains a mystery. With that knowledge, however, a plausible explanation exists that is, in my opinion, the only explanation.
Now it is imperative that one more crucial step be taken. I am asking the Mine Safety and Health Administration (MSHA) to revisit the Sunshine Mine Fire Disaster, not to satisfy me or to impeach the conclusions of the "Final Report," but to establish—or disprove—the danger to human lives in any and all places where exposed P1W is currently in place. MSHA, part of the U. S. Department of Labor, is now the regulator for mine safety and health. USBM and the Department of Interior are longer enforcing mine health and safety. By the way, I send a copy of each article to MSHA in Coeur d'Alene. They will read this before you do.
I have no way of knowing the current status of PUF use in underground mines. I do know it was used in coal mines, metal and nonmetal mines, and railroad tunnels. I can say with confidence, however, that the product is not used in large-scale applications in any of the mines in the Silver Valley.
A good source of additional information about PUF use is an article entitled General use of MSA Rigiseal Urethane foam by George L. Alston, Special Mining Products Division, Mine Safety Appliances Co., printed in the Canadian Mining Journal, September, 1964. I wish to quote parts of the article.
"For the past ten year, our company has been studying various methods of erecting stoppings in mines with cheaper material, less labor and for more effective air control. This study covered more than 75 different materials to replace the conventional concrete block It was not until 1961 when the U. S. Bureau of Mines and Mine Safety (MSA Co.) made a joint study on the use of urethane foams that a practical answer to the problem seemed at hanrL Various chemical companies participated in the research and the inherent faults of the urethane foams then on the market had to be overcome. There were two primary reasons why the urethane foams cold not be used in the mines. First, the isocyanates that were generally available on the market were quite toxic and second, the flnishedfoam was highly combustible"
"A new isocyanate was then under development which, although somewhat toxic is considerably less so than that which had been used in the past. Secondly, a fire retardant material was added to the chemicals, which causes the resultant foam to be self-extinguishing. A set of rigid standards were outlined by the U S. Bureau of Mines to assure that any foam used in the mines was not harmful to the personnel working in the mines and that any foam used for ventilation control would pass a specifIc fire retardancy test.
Other information from Mr. Aiston's article includes the following:
- The first Rigiseal machine was installed in Kaiser Steel Company's mine in Carbon County, Utah in 1962. Since that time "more than 200 machines have been put into service. As of today, more than 800,000 pounds of Rigi mix have been used in mines." (the article was published in Sept. 1964)
- More than two miles of railroad tunnel for Southern Railway Company have been covered with Rigi seal to prevent spalling and sloughing. This work was done in mid-63 and as of today, is standing up exceedingly well."
It is appropriate to comment briefly about other uses of PUF that I have witnessed. About twenty years ago, I took my family to the Casa Bomta, a large Mexican restaurant in Denver, Colorado. A large portion of the restaurant was made to resemble underground mine openings. The effects were accomplished by spraying PUF over wire mesh.
The last place I saw a major application of P1W was in an industrial building near Bellinghain, Washington. It was a steel structure with about 3,000 square feet of floor space. Hulls for fishing boats were manufactured there. The entire interior of the building was coated with PUF. It is, after all, very good insulation!
I informed the building owner (my brother-in-law) of the extreme fire hazard. I told him the story of a pig barn near Albert Lee, Minnesota that was also insulated with non-burning; self-extinguishing polyurethane foam. A fire ignited by a defective oil heater destroyed the building. One hundred pigs died in the fire. As I remember the details, the suppliers of the product ultimately paid about $10,000 for each pig.
For now, let it suffice to say that "non-burning" and "self-extinguishing" P1W, approved by the USBM for use in underground mines, is a potentially deadly product—a far cry from KNOCKS FiRE COLD - Mining & Quarrying; August 1962:
A revolutionary method of insulating and sealing passageways In coal and metal mines by applying sprayed-in-place urethane foam to exposed underground surfaces was demonstrated by the U. S. Bureau of Mines for the American Mining Congress in Pittsburgh on May 10...Since the foam sill not supppll combustion, it can be used to insulate combustible materials in the mine and makes possible the quick erection of emergency, flame-retardant curtain walls to localize an outbreak offire underground."
Indeed, in the mining industry — England, USA, and South Africa — and research by USBM leaves little doubt that the initial classification of non-burning and self-extinguishing was not appropriate for large scale applications of polyurethane foam. Now it's time for MSHA to set the record straight.
Put Yourself To The Test
For the past ten weeks, I shared details of the Sunshine Fire, the layout and conditions in the mine at that time, and changes that were made to prevent a similar disaster. I quoted thoughts of industry leaders about fires in hardrock mines, thoughts and beliefs that were shared by personnel at the Sunshine Mine. Sadly, those beliefs were wrong.
Now I am asking you to put yourself to the test. You too can learn from history. The lessons to be learned are critical to safety in underground mines. They also speak strongly to commercial and residential fire safety. Before moving on, I want to express my thanks to J. B., a reader whose comments motivated me to write today's article. Thanks, J. B.! You have proved what has been said many times—"never underestimate the ability of an informed public to know what's going on."
Following are summaries of hardrock mine fires that are classified as disasters. There are several key and common denominators that caused these fires to become disasters. By the way, the term "disaster" is applied when any one accident results in five or more fatalities.
Granite Mountain Mine in Butte Montana - June 1917 -- 163 died in a shaft fire, caused by accidental ignition of oil soaked insulation on a power cable. A new electric cable had been lashed to the hoist cable so it could be lowered into the shaft. The lashings failed, allowing the cable to drop into the bottom of the shaft. Impact caused the cable to break open, exposing oil- soaked insulation materials. One of the people examining the damaged cable was using an open carbide light for illumination. Accidental contact with the insulation started a fire. There was no readily available and adequate means to extinguish the blaze. Surrounding shaft timbers were ignited. The "chimney effect" quickly turned a small fire into an inferno. The shaft was the main intake airway. Combustion gases spread throughout the mine.
Argonaut Mine in California - August 1922-47 died when a fire occurred in the main shaft. The fire was probably caused by an electrical short in a high voltage power cable. The shaft was the main intake airway. Combustion gases spread throughout the mine.
Magma Mine in Arizona - November 1927 - 7 died when a fire of unknown cause occurred in an intake air shaft. Combustion gases spread throughout the mine.
Glenn Mine in California - July 1930 — 5 died when a fire of unknown origin burned the compressor house, shop, powerhouse, and snowshed, all of which were connected to the mine portal. The portal was the main intake airway. Combustion gases spread throughout the mine.
Braden Copper mine in Chile - June 1945 — 354 died when a five-gallon container of oil being warmed ignited. Combustion gases spread throughout the mine.
To my knowledge, the Braden Copper disaster is the world's worst hardrock mine fire disaster. Last Saturday I phoned John Reed, a retired mining engineer and mining school professor who was working in the mine when the fire occurre& I wanted to know more about the disaster.
The mine is in the mountains of central Chile, 7,200 above sea level. June is the middle of winter and very cold. The fire, occurred in a mine car repair shop located in the mouth of a mine tunnel. To protect eniployees from the cold, a wall constructed of wood and covered with tar paper sealed the mouth of the tunnel. A door provided access.
It was the beginning of the morning shift. The car shop was cold, as were the employees built a fire in a forge. One of the workers placed a 5 gallon container of lubricating oil on the edge of the forge so it could be. He then joined other workers at a warmer location taking a "break" and forgot about the oil. It over heated and ignited.
The initial fire burned slowly because the car shop was tightly seâFed to keep the cold air out. A compressed air line was available for the forge but had not been opened. The limited air supply resulted in a smoky oil fire, high in carbon monoxide. The fire spread to the tarpaper and wood in the bulkhead. Weakened by burning, the bulkhead collapsed, allowing a rush of air to the fire which caused a low velocity explosion, pushing carbon monoxide and smoke into the interior of the mine. Death from carbon monoxide came quickly to 354 employees.
John Reed was with a group of employees in a section of the mine connected to a newly completed tunnel that opened on the mountainside. Although the opening was nominally sealed,.a small amount of fresh air leaked past the seal into the.mine. That separate source of ventilation air allowed John and his group.to escape unharmed.
John did attempt to help the rest of the crew engulfed in the smoke. He told me about the telephone to learn more about the fire. To reach a phone he had to pass through a ventilation control door into thick smoke, he had to remove the carbide lamp from his miner's cap and hold it close to the rail on the floor of the drift. However, recognizing the early symptoms of carbon monoxide poisoning; John returned to the fresh a His group.
Mine in Mexico April 1953-35 died when a man-caused flre nson 1 a accelerated rapidly due to the "chimney effect" and inundated the area which spread throughout the mine.
Last week's article provided a profile of five hardrock mine fire disasters and a challenge to the reader to identi1 the lessons taught by the fires. You might have wondered why Sunshine and Kinross were not included. My reason was that those fires had already been thoroughly discussed. Polyurethane foam (PUF) was strongly implicated in the Sunshine Fire and the acknowledged culprit in the Kinross disaster.
After completing his investigation of PIJF in a British Coal mine fire disaster in the early 1960's, D. Graham Wilde, former head of the Mine Fires Section of the British Health and Safety Executive strongly reconunended that PUF be banned from use in mines. Regarding other highly combustible materials, Mr. Wilde suggested that, ideally, materials introduced in quantity in mines should be no more combustible than wooden mine timbers. In an article published in the Journal of Fire & Flammabiity Vol. 11 (October 1980) under the heading "Discussion," he writes, "It would be impracticable to insist that all materials taken into mines should be non-flammable. The most that can be expected is that, having regard to their quantity and manner of distribution, the flammability of mining materials should be reduced to levels below which dangerous fires cannot occur."
Graham Wilde continues, "The flammability of a material is usually expressed in terms of measured rates of spread of flame. In confined surroundings, such as a mine, an additional aspect that must be considered is the ability of a material to give rise quickly to large volumes of flame. Large flames, burning in limited air, in turn cause high concentrations of toxic gases and high temperatures in the fumes."
That brings us to a major point in understanding mine fire disasters—the vastly different flame spread rates between timber fires and PUP fires in horizontal mine openings. A. F. Roberts and J. R. Blackwell, British researchers in fuel-rich mine fires, published a report indicating that fire in a timbered mine opening advanced at a rate of 2.3 to 17.1 yards per hour. That is quite a contrast to "non-burning and self-extinguishing" PUP th a rate of advance of 0.7 to 2.5 yards per second. Those results were measured during a test in an SMRE facility near Buxton, England in October of 1976. That test was conducted and documented by Graham Wilde. I participated in those tests.
Having looked at the extreme differences in the behavior of mine timber and PUP in mine fires, we now return to the analysis of last week's fire disasters. The Granite Mountain fire was accelerated by oil-soaked insulation in the ruptured electrical cable—certainly more flammable than mine timbers. The Braden Copper fire involved five gallons of lubricating oil that was heated above the flashpoint and burned in an oxygen-deficient environment, giving rise to extremely high levels of caibon monoxide. Such a fire is not in the same league as a mine timbers fire.
Argonaut Mine, Glenn Mine, Granite Mountain and Magma Mine fires occurred in vertical or steeply inclined intake airways. Because of the "chimney effect,", the normal rate of flame advance in timbered mine opqnings is not applicable to a shaft or raise fire. The consequences of the fire are compounded if the shaft or ventilation raise is the only source of ventilation air to the mine.
So, what should the reader have learned from the mine fire disasters? In the event of fire in an intake air shaft or raise, a means should be provided to isolate the dowzmmd areas of the mine from the fire and its combustion gases. Fire doors readily can achieve this goal.
Flammable liquids have no place in underground mines, nor do combustible liquids th a low flashpoint. The inherent fire hazards of all combustible liquids and solids must be given due consideration. Modern mining includes widespread use of rubber-tired haulage equipment, much of which is powered th diesel engines. Improper use or maintenance of such equipment can result in fires in which fuel, lubricating oil, gear lubricants, hydraulic fluids and tires can burn. Proper design of mine ventilation systems and ventilation controls can minimize the danger of such fires by making it possible to isolate personnel from the combustion gases.
Another lesson to be learned from the Braden Copper fire, as well as the Sunshine fire, is the added measure of safety of a second source of ventilation air that can be isolated from the primary source. Ron Flory and Tom Wilkinson survived for a week in the 4800 west lateral, provided with ventilation air through the No.12 borehole. John Reed and his crew in the Braden Copper mine survived in a tunnel connected to the outside and ventilated by a small volume of air flowing inward.
In my opinion, the ability to control mine-wide ventilation in the event of a fire is the highest priority in mine fire safety.
Occupants of high rise buildings can survive a fire if they have access to a stairwell that is properly constructed, provided that all fire doors leading from the stairwell into hallways are kept closed. Think about fire safety the next time you are in a high rise building and find fire doors wedged open. Yes, I know — it's a pain in the neck to have to open and close those doors every time you pass through. But if there's a fire, who will close them?
Speaking of stairwells—perhaps you can now understand why they are so stark and bare. If properly constructed, they contain nothing more combustible than concrete and steeL In contrast to bare concrete and steel, I can't help but think about pibhc building which, in some cases, have stairways that are not only carpeted on the steps, but on the walls as welL It really offers a plush and quiet stairway. Guess what — stairways are just as vulnerable to the chimney effect in fires as are mine shafts and raises.
Perhaps this series of articles will stimulate serious thoughts about fire safety in the home, the workplace, in public buildings, and in recreational activities. Concern over ease of ignition and rate of flame spread is vital in relation to buildings, yet perhaps more important for children's clothing. It also applies to storing the extra can of gasoline for the pleasure boat or the ATV. Perhaps someone will think twice about putting a 5-gallon can of gasoline in a bracket on the rear bumper of a pickup or RV. (Far more dangerous than the Ford Pinto.) Talk about an accident waiting to happen! More next week.
A statement frequently repeated in my series is that the May 2, 1972 Sunshine Mine Fire was no "ordinary" mine fire. In only a matter of minutes, a light wisp of smoke gave way to a heavy, dark and toxic inundation that continued unabated for hours. The smoke obscured the level indicator on the main personnel hoist—the No. 10 Chippy—and drove the hoistrnan out of the cab in search of better air, thus depriving the crew of rapid hoisting. This all happened within the first fifteen minutes. A comparison with an "ordinary" mine fire seems appropriate now.
Before moving on, I must comment about the loss of use of the No. 10 Chippy hoist—a subject scarcely mentioned in any of the reports. Unlike the main hoist with a trailer deck under the muck skip on which ten men could ride, the No. 10 Chippy had a four deck conveyance with room for forty-four passengers per trip. It is hard to know what would have happened if it had operated. There is a strong possibility that more lives would have been lost, had the crew all been hoisted to 3700 level using the Chippy hoist. Allow me to explain.
The worst of the deadly smoke and fumes first crossed the 3700 level drift and poured into No. 10 shaft. For another twenty to thirty minutes, the 3100 level was essentially free of heavy smoke. I know of only two people who survived on May2 after leaving the 3700 No.10 shaft station and vicinity and walking across the 3700 level to the Jewell shaft. Several deck loads of men were hoisted from the 3700 No. 10 station to 3100. Most of them survived. Others who chose to escape on the 3700 level perished.
Another scenario is possible. Had the Chippy hoist been in operation during the early stages of the fire, and had the personnel on duty understood the dynamics of the ventilation short-circuit, the Chippy could have been used to hoist the crew rapidly from the lower levels to 3700 while the 3100 double-drum could have hoisted them from 3700 to 3100. That's 20/20 hindsight; maybe it's not worth speculation.
Now we continue the comparison to an "ordinary" mine fire. An excellent example is found in the Magma Copper, Superior, Arizona fire of December 2, 1961. The information, including quotations, is from the Mining Congress Journal September 1962 and was written by Bruce Short, Ventilation and Safety Engineer, Magma Copper Co.
The fire started in a caved section that had been mined out, except for a small pillar that had been left to help stabilize the 2900 level drift until mining was finished above that level. In 1957, the caved section was sealed so ventilation air could not enter. Prior to December 1962, the mining above 2900 level drift was completed. Shortly before the fire, "a sub-level drift was being driven towards the sealed area to recover the small pillar of ore remaining in the caved section. Drifting began toward the pillar just below the 2900 level. The fire started by spontaneous combustion when drill holes from the new drift admitted air into the sealed area."
Spontaneous combustion? Yes! There were two significant differences from the 3400-09 area in the Sunshine Mine. Bruce Short wrote: "Rock temperatures at this elevation in the mine are 135° F," (compared to 80° at 3400-09 in the Sunshine Mine,) "high enough to distill volatile compounds from the old mine timbers," and copper sulfide ore that oxidized rapidly and at high enough temperatures to ignite the old mine timbers. Oxidation of copper sulfide ores in contact with mine timbers is a common source of mine fires. Butte mines experienced the problem. So did the Sullivan Mine in Kimberly, B.C.
How big was the Magma mine fire? "Investigation had shown that the fire was centered in a mined-out section of the 2900 level in an area roughly 1,200 by 1,000 feet square, between the 2800 and 3000 levels. Within this zone were several vertical and inclined raises of various dimensions, an interior air supply shaft, and over a dozen openings that were feeding air to the fire. All workings were extensively timbered and rock temperatures were known to be high." It was a big fire!
Quotations from the official fire log tell the rest of the story. Please note the significant lapse of time between the initial detection of smoke and the decision to begin an evacuation of the crew.
Saturday, Dec. 2. 1961
11:00 am: "Level boss reported to general superintendent that he smelled wood smoke on 2920 level at 5 2/5 raise. Level boss asked to check again. Level boss reported back—definite wood smoke. Further checking showed smoke on 3000 level, 54 1/5 raise."
12:00 noon: "Fire warning stench started Level bosses called on mine telephones to move all men out of mine."
12:30 pm: "General superintendent and (undecipherable) man prepare to go underground. All men on day shift coming out."
1:15 pm: "All men on day shift accounted for. Train crew report smoke on 2550 level from E24 to E43 winze.
Superintendents and mine rescue men equipped with self-contained breathing apparatus enter mine. Enough smoke to sting eyes between E24 and FA3 on 2550 level.
1:45 p.m Mine rescue men go to sections on 2550, 2800, and 3000 levels to investigate conditions. Men go down 54 1/5 raise to 2900 level. Hazardous conditions on 2800 leveL Mine rescue men on 1550 level go with apparatus to 2800 level."
Sun., Dec. 3 - 4:00 am "Hose crews on 2900 level backed out by smoke. Exhaust air tested and showed 1.0 percent carbon monoxide
10:00 a.m - Carbon monoxide reaches two percent on 2550 level
There you have it—a fire that slowly grew in size as air became available. But look again at the time frame! The level boss smelled wood smoke and reported that fact at 11:00 a.m. One hour later, at 12:00 noon, the stench warning system was activated. At 12:30 p.m. the day shift crew was on the way out. That's one and one-half hours after smoke was first smelled! At 1:15 p.m. the crew was out of the mine and accounted for. An "ordinary" mine fire, but certainly larger than most. The crew all escaped safely. No self rescuers were used.
Most people who frequently enter different mines will be able to identify the mine they are in by its odor. In addition to the Sunshine, the Star and Bunker Hill mines are two that I remember very well. Mill tailings used for backfill add a distinct bouquet to the mine atmosphere, carrying trace odors of various reagents used in the flotation process.
Even a tiny, smoldering fire will quickly overpower the customary mine odor. For that reason, the sense of smell is regarded as one of the very best tools for early detection of fires in mines except for perhaps five out of one hundred people who are anosmic. So what was it like in the Sunshine Mine during the lengthy mine fire?
I will begin with the odor. For me, that feature is the most memorable. For comparison, I refer to the aroma of the now closed Shoshone County landfill during periods of incineration. That odor was objectionable to most people, as was the odor of burning wood during the mine fire. It's a subjective thing that I cannot explain—not pleasant and quite a contrast to the smell of a campfire which most people enjoy. The odor of the mine fire filled the area near the mine surface buildings.
Now you will journey with me into the mine fire zone. The details are all from memory, not from any daily log and may have taken place over a period of days or even weeks.
Before entering the mine, we don self-contained breathing apparatus (SCBA). We leave the Jewel Shaft 3100 level station and walk south through the main crosscut. Time and distance seem to expand as we walk into the unknown. Now we come to a "Y." To the right we see a ventilation door through which we could access the No. 4 shaft and hoistroom. Rather, we turn to the left and enter a meandering drift; lined with limber. We are now passing through part of the mined-out Sunshine Vein—one of the richest silver deposits in the world. Evidence of recent work quickly catches our attention. A material identified as plastic coated burlap, coated with polyurethane foam, lines major stretches of the drill Crews wearing self contained breathing apparatus are busily at work in their efforts to construct a ventilation conduit to the No. 10 hoist several thousand feet beyond.
We enter a large excavation known as the Timber Station. There we view a number of strange looking copper-colored flasks. They look like something out of a science-fiction movie. They are containers of liquid oxygen, used to fill the evaporators in the SCBA used by the Canadian mine rescue teams.
We continue our eastward journey, passing numerous places where " have been placed to stop the flow of smoke into the 3100 drift. Then we come to another "Y" where several mine rescue crews are at work Wayne Baxter is in charge and tells us in no uncertain terms, "This is as far as you're going today." To the left is an opening into "D" drift. A partial sand plug has been poured—mill tailings piped into the void between two wooden walls built up about two feet above the floor of the drift. Beyond the seal, flickering flames can be seen through a light haze of smoke. One crew is about to extend the wooden walls to the top of the drift so a solid sandflll plug can be poured. This is of extreme importance. The sandfill plug will cut off the air supply to the fire through the "D" drift.
In the meantime, another crew using a "diamond drill" continues to drill upward at about 45 degrees to intersect the "I" vein above the 3100 level. As soon as the hole is finished, sandflll will be poured through it into the fire zone below. What we see is only one of dozens of similar projects. Seals and sandfill plugs are placed where access is available. Diamond drill holes are drilled into mined out vein structures and sandfill is pushed through the drill hole until it "won't take any more." This technology was widely used in extinguishing the fire.
Now we are on another adventure, this time across the 3700 level, through the 08 Shop and up through an abandoned ladderway to the 3550 level. Don't want to go there! I can understand. It's a hazardous venture, but ... here we go anyway! I must tell you this was not part of the mine investigation plan. I did it on my own, spurred on by a desire to approach the center of the fire zone as closely as possible. Wayne Baxter and Harvey Dionne told me about the ladderway adjacent to the No. 8 shaft that might still be open to the 3550 leveL. I decided to give it a try.
The ladderway was tight so SCBA could not be worn. My memory fails me as to the identity of the person who went with me—probably Wayne Baxter or Harvey Dionne. As we climbed the ladder, one carried a flame safety lamp while the other carried a multi-gas detector. Conditions continued within safe limits. We reached the 3550 level and stepped out of the shaft ladder into a layer of very fine ash. It was hot, reflecting a rock temperature of about 90° F. As I remember, carbon monoxide was about 100 ppm, allowing us a safe excursion for about 15 minutes.
We made our way as far as we could into the 08 vein area. At that point, the ash was six to eight inches deep. Lookng ahead, above, and below as far as our cap lamps could reach, we saw only a gaping, blackened chasm, ranging up to ten feet in width. As the timbers burned, the loose gob-fill in the stopes dropped to the bottom of the mined-out area.
We then walked to the east, past No. 8 shaft The depth of the ash quickly diminished, indicating a very low velocity air current through that area during the fire. Several hundred feet to the east of No. 8 shaft, ash was no longer visible on the floor of the drift. We returned to the 3700 level.
Once again you will travel with me into some out-of-the-way places in the mine, mostly to satisfy my obsession for clues that might explain the cause of the disaster. Please remember that, at this point in time, no one on the investigating team is aware of the hazards of PUF, so its role in the disaster is unknown.
As mentioned in Part II of this series, access to the acknowledged site where the fire started at the 3400-09 bulkhead was made by a mine rescue team soon after the No. 10 hoist was put back into service. Also stated was that, prior to the next shift, a cave-in of the 08 vein area occurred due to the fire, completing blocking the 3400 drift—the only access from No. 10 shaft to the 09 area.
As part of the mine reopening plan, workers began to restore the 3400 level exhaust airway. The No. 4 hoist was reactivated to provide access to the west end of the 3400 level. Mine rescue crews constructed an "air lock downwind from the 09 intersection. An "air lock" consists of two ventilation doors far enough apart to allow room for haulage equipment to pass through and then close the first door before opening the second. Why was this necessary at this location? Well, come along with me and see for yourself
For this trip, we will use one the twenty "Aerlox" SCBA units purchased from a supplier in England and transported by the United States Air Force to Spokane. Additional SCBA's were desperately needed. McCaa and Draeger units were not available; only Aerlox were available, in place of a high pressure oxygen cylinder, the Aerlox uses an evaporator filled with liquid oxygen to provide oxygen to the wearer. Although not approved by USBM for use in mines, the Aerlox quickly became the SCBA of choice for many of the mine rescue personnel, including USBM personnel. They were lighter than the McCaa or Draeger apparatus and supplied oxygen into the face mask at a cool 65° F—quite a contrast to the 100° to 120° in the McCaa and Draeger units.
We descend through the Jewell Shaft to the 3100 level and walk about 1,000 feet to No. 4 shaft, board the cage, and are lowered to 3400 level. I explain the purpose of the flame safety lamp and multi-gas detector I am carrying. You notice the smaller size of the drift. I remind you it was driven about twenty years ago. Mining equipment was maller then. One thing was certain; they didn't make any opening bigger than it had to be!
There's mud on the floor of the drift, so we slip and slide as we walk to the east. We pass through a ventilation door constructed of Y2" thick steel plate. I tell you that the door separates the western part of the 3400 level from the exhaust airway. Just beyond the door and to our left, we see the drift that carries the exhaust airflow to a series of raises and shafts that lead to the surface.
As we proceed, we notice there is absolutely no air movement. It's hot! You ask if it's because we are getting closer to the fire. I assure you that's not the problem. We are feeling the effects of 88° rock temperature, 100% relative humidity, and no air movement Perhaps five minutes later, we come to the first of two air lock doors. The flame safety lamp is burning brightly. I use the gas detector to check for carbon monoxide and carbon dioxide. The atmosphere is "normal."
A member of the mine rescue crew working in the area cautions us about going through the second air lock door. Having listened carefully during the debriefing sessions in the operations center on the swface, I know we are about to enter a high hazard zone. I open a small trap door built into the air lock door. As I move the flame safety lamp into the opening, the flame instantly is gone. Previous low-oxygen readings are verified.
Now it's time to use one of the new high-range carbon dioxide detector tubes. The tube indicates a concentration of 19%. What's going on here? This isn't mentioned in the training manuals!
The cave-in of the 08 vein blocked all air movement to the east of the 09 vein. The air lock doors blocked all air movement to the west. (Those doors were essential for the safety of personnel as they worked to recover the 3400 drift.) Fires were still burning in remote parts of the 08 vein, 09 vein, and "D" vein. A major fire gas is carbon dioxide (CO a gas 1.5 times as heavy as air. Due to its weight, it settles into low places.
Here's what happened in the 09 vein. Timbers in the airways and raises, as well as timbers used to support the walls in the stopes during mining burned. The gob, consisting of mine waste rock then dropped to the bottom of the mined-out areas. With no timbers left to interfere with compaction, the gob formed an air-tight seal at the bottom of the mined-out area. The CO produced by ongoing combustion settled to the bottom, due to its weight
Being assured that time area had been carefully checked for loose rock, we cautiously approach the 09 vein and look down into a chasm about eight feet in width. Our cap lamps fail to reach a "bottom." All the timbers and waste rock that had once filled the slopes and supported the drift and manways were gone. It reminds me of photos from the last major Alaskan earthquake.
Vacuum bottle samples taken from the area indicated less than 1% oxygen, 18 to 20% carbon dioxide, 400 ppm carbon monoxide, and a trace of hydrogen. Removal of the SCBA face mask in such an environment would result in immediate death.
The buildup of CO just described will not come as a suiprise to experienced firemen. Many lives have been lost in multi-stoiy building fires when firemen entered a basement in which the heavier CO generated by the fire burning above displaced the normal atmosphere. Even firemen wearing universal gas masks perished in basements. Although protected from dangerous fire gases, the masks did not generate oxygen. Thankfully, today's firemen have SCBA's to protect them from the hostile fire gases and oxygen deficiencies.
Knowing what you have just learned will hopefully convince you to leave a burning building as quickly as possible, and above all, never to attempt to re-enter during a fire.