Mine Inspection Report
BETHLEHEM NO. 41 MINE EXPLOSION
(Ar1519)
An explosion occurred at the Bethlehem No. 41 mine of the Bethlehem Mines Corporation on March 17, 1925, at 9:55 P. M. At this time there were thirty-three men at work in the mine, all of whom lost their lives.
This mine is located at Barrackville, a few miles from Fairmont, on the Baltimore and Ohio Railroad, and was opened in 1909.
Three shafts, 500 feet in depth, penetrate the Pittsburgh No. 8 seam, which is developed on the four entry system with double entries turned off at right angles from the main entries. The room and pillar system is used in this mine, and it is operated on a closed light basis. When operating full capacity it employs 400 men and produces about 2,000 tons of coal daily. It liberates explosive gas freely and has a tendency to dry out rapidly, making the dust problem very hard to overcome.
Realizing the hazardous condition of this mine, the following organization was maintained at all times: A mine superintendent, mine foreman, four fire bosses, five section foremen, one safety foreman and six shot firers. They also had two boss drivers and one shaft bottom boss, all of whom hold first class certificates.
Safety meetings were held weekly by the section bosses for the purpose of discussing safety measures and other matters incident to the operation of the mine. Once each month a general meeting was held by all certified men in official positions, and those in attendance were given an opportunity to make recommendations and to bring up and discuss matters pertaining to the safe operation of the mine.
A few months ago a new system of handling explosives was put into effect. An accurate record of all explosives issued was kept daily by a man designated for that purpose. The miners carried the explosives, and the shot firers carried the detonators, which prevented any person from firing a shot except those authorized. All explosives taken into the mine in the morning were checked, and another check was made when the miners and shot firers returned their explosives and detonators to the magazine outside.
Each person entering the mine, regardless of what shift he was working on, was searched for matches, or any device for making light or fire not authorized or approved.
The fire bosses made regular inspections, as required by law, prior to the entrance of men, and all places to be cut on the night shift were examined by the section bosses. In addition to this, after the machine men had out all places, a certified man was designated to ascertain if all doors were closed, all switches pulled and everything done to insure the safe operation of the mine. In addition to the regular daily inspection by the machine boss, all mining machines were thoroughly examined once each month by the safety engineer to determine whether or not they were properly fused and the cables properly grounded. All places were examined for gas and other dangers by the machine men before taking the machines beyond the last break through, and, upon the discovery of gas or other dangers, the place was immediately "dangered off" until it could be made safe. All machines were equipped with approved flame safety lamps, and at intervals the machine men were instructed in their proper use for the detection of explosive gas.
Ventilation was produced by electric and steam exhaust fans, twelve feet in diameter with a speed of 158 revolutions per minute, producing 210,000 cubic feet of air. At the last break through the air was always in excess of 10,000 cubic feet. One fan was kept in operation and the other maintained for emergency. On alternate days air samples were taken throughout the mine and copies of all analyses were mailed to the Department of Mines. At no time in the past four years has a methane content in excess of one half of one per cent on any air split been permitted.
The high velocity of air quickly dries out the mine and picks up enormous quantities of coal dust from the loaded trips as they proceed outward against the intake air. To safeguard against this danger all accumulations of loose coal and dust were loaded out once each week. All loaded cars leaving the side track were saturated with water from an overhead sprinkling device. This sprinkling system was also used on all empty cars as they proceeded inward from the shaft bottom. Sprays were kept open on haulways, producing a fine spray of water which was carried for hundreds of feet. Every two weeks during the winter months the entire mine was thoroughly washed down with water, a hose being used for this purpose, which was attached to pipe lines laid on all entries. Water was supplied to all working parts of the mine and maintained at a pressure sufficient to thoroughly wash down all particles of coal dust from ribs, roof and timbers. The rooms were washed down in the same manner.
The words "mine explosion" create a profound emotional reaction, and it is impossible to describe just how one feels. At the time of this explosion I was on board the night train from Morgantown to Charleston, and a few minutes after arriving at Grafton the porter called me, stating that the Barrackville No. 41 mine had blown up. Accompanied by M. B. Mitchell, the superintendent, who was traveling to Charleston, and District Mine Inspector Robert Lilly, we almost immediately started for the mine as the Baltimore and Ohio Railroad officials had a special train ready in a short time, which made a record run from Grafton to Fairmont, arriving at the mine at midnight.
After making a hurried survey of the fans and manshaft, work was concentrated at these two points, there being a great number of men on the ground who were capable and anxious to do this work. The steam fan was blown out of alignment, and the door at fan drift of the electric fan was badly bent and hung. This work had to be performed by men using All Service Masks as after-damp was coming from the mine in a heavy volume. The cage at the man-shaft had been blown almost tb the sheave wheel, and the shaft was damaged so badly that it was necessary to chain the cage where it hung. By taking the rope off and making a hole through t he top and bottom of the cage, we were able to have a bucket ready by the time the fan was in shape to operate. At 5:00 o'clock A. M., accompanied by a companion, I descended to the shaft bottom and made a thorough examination of all places close to the three shafts. We were equipped with All Service Masks, and established a telephone communication to the outside. This permitted us to keep the men on the outside advised as to what we found, what we intended to do and how long we would be gone. After completing this survey, we returned to the outside where rescue squads were organized.
All the men on the ground were classified as to their qualifications and the kind of work they were best fitted for. In this way we were able to have well balanced crews. All work was placed on a six hour shift and the men listed and advised as to the time they should report for duty. Each shift was in charge of a district mine inspector assisted by a representative of the United States Bureau of Mines and a company official. There were also on each shift a fire boss and an assistant foreman, so we had the advice at all times of men who were familiar with the mine. A complete crew consisted of five men who were equipped with Gibbs Self Contained Breathing Apparatus, five men with Burrell All Service Gas Masks, twelve men on stoppings, twelve men transporting supplies, four men at shaft bottom and the supervising crew, which was generally composed of six men.
The first two hours, after the preliminary examination, were taken up with getting supplies down the shaft and establishing base No. 1 close to the shaft bottom. Telephone communication was made to the rescue car, and while this was being done a general plan of recovery was mapped out, which was to advance as quickly as possible to Nos. 1 and 2 butts off 8 south face on main west butt, as it was known that the greatest number of men in the mine were at this point. This section also afforded a good chance for the men to barricade themselves off as only two stoppings were needed, and, if the violence at this point had not been great, a possibility existed of these men being alive. However, as we proceeded, with improvised stoppings we were horrified to discover an immense volume of smoke, which we decided was from a mine fire, undoubtedly at some point on main north face.
Those who have fought mine fires will understand the thoughts that flashed through the brain of each man present. To be in a mine liberating explosive gas freely, the ventilating system entirely disrupted, with a mine fire at some unknown point, and not knowing what minute the mine was likely to blow up again, was indeed discomforting. The fact that in the 1916 explosion rescue squads had just reached the outside when the mine again exploded was enough to upset the routine of things for a few minutes. The general plan of work had to be changed, and it was necessary to make all possible haste to the point of fire, hoping that we could reach it before the mine atmosphere reached the explosive point. Times such as these, when men face danger together, bind them more closely to each other, for these men knew the hazard and they realized that it was a fifty-fifty proposition whether the mine atmosphere would reach the explosive point at the fire or whether it could be reached with a fresh volume of air and the explosive hazard eliminated. However, there was no time under conditions of this kind to figure on the possibility of failure, as all thought and energy had to be concentrated and directed toward success.
No man in such a crisis was blessed with more courageous and able men than I had at my command in this emergency, and, as the map was carefully charted with a stopping here and a stopping there, the men worked as they had never worked before. About midnight the day following the explosion we reached the fire, which was a raging furnace. This fire was inby the mouth of fifth left butt off main north face and extended a distance of 175 feet. A hasty examination of the mine atmosphere just inby the fire, made possible by using Burrell Gas Masks, revealed the fact that an explosive mixture of gas was less than 75 feet away. The next few hours were the most trying imaginable as we did not have the ventilation in sufficient volume to remove this immense body of gas, there being over one million two hundred thousand feet of gas at that point, most of which was on top of gobs where the pillars had been extracted. However, we soon had a sufficient volume of air to deflect over and around the fire which carried off and diluted the heavy volume of gas, thus removing the gas hazard from the fire zone for all time. This heavy volume of air acted on the fire the same as a force draft at a furnace, but the removal of the gas from the fire zone was of the greatest Importance. As soon as it was deemed safe to change the ventilation around the fire zone, this was done and carried out by using canvas stoppings and checks for deflecting the air current. Then the fight to subdue the flames commenced, and with two lines of hose with a two hundred pound pressure a straight attack was made; and as the flames were lowered those brave men would follow, crawling on hands and knees over the red hot coals. There was great danger of falling roof owing to its being exposed to such high temperature and the sudden change brought about by forcing heavy volumes of water/low temperature on the fire, roof and ribs, but this danger was minimized by setting short safety posts to protect the men as they advanced. This fight was maintained until all flames were extinguished, then dams were hastily built around the fire zone to submerge the burning coal. This worked very successfully, and the task of building the seals was made comparatively easy. After the completion of the seals the temperature in the fire zone fell rapidly. However, as an added safety measure, a patrol of two men on each shift was detailed to the fire zone and instructed to keep the seals in proper condition to prevent leaks. After this was done, the men felt somewhat relieved, not withstanding the fact that they realized they had yet many difficult and dangerous tasks to perform before they could reach the entombed men.
In the actual recovery of the bodies, after the fire hazard had been eliminated, it was just a case of maintaining sufficient ventilation to carry off and dilute the dangerous gases that filled every portion of the mine. The advance guard, which was composed of men wearing Burrell Gas Masks, performed ninety-five per cent of the exploration work, five per cent being accomplished by men wearing Gibbs Self Contained Breathing Apparatus. Following these men were the brattice crews, who were equipped with gas masks and often compelled to wear them, and then the transport men.
Telephone communications were established just as fast as the gases cleared out. There were eight telephone stations in all. These points served also as supply bases. The entombed men were in practically every section of the mine, which made the recovery work slow. However, the entire mine was explored and all bodies brought to the surface in less than six days' time.
While this great fight was going on, our Governor was on the job day and night, seeing that everything was done to take care of the dependents and to hurry supplies into the mine as requests were made. When the first bodies were brought to the surface he was there lending his aid, and he remained on the scene until the last bodies were removed from the mine.
The State Constabulary was also on the job just a few minutes after the explosion, and the men in their quiet, courteous and efficient way took charge of the situation, and in a very short time everything was being conducted in an orderly manner. In fact, there was no confusion at or near the mine as is generally the case at explosions.
It has already been stated, that this mine liberates explosive gas in dangerous quantities and that coal dust is a source of great danger, but, inasmuch as the inquest has not yet been completed, it is impossible for me to express my opinion as to the cause or the point of origin. However either of these could have been the cause.
If this explosion was started by the ignition of a pocket of explosive gas, it is possible that the shock and pressure waves threw sufficient particles of fine dust in suspension to propagate the flame throughout the mine. Supposing it was started by the ignition of coal dust alone, it could have been propagated throughout the mine, for it has been demonstrated that fine, dry bituminous coal dust, when in suspension in the air, can be ignited by an open torch. However, before this can be done, the atmosphere must have a relatively high density such as one sometimes sees at mine tipples. Fine bituminous coal dust having ten per cent or more of volatile can be ignited when in suspension in the air, and the greater the percentage of volatile matter, the easier the ignition. The coal at Barrackville is high in volatile having a per cent of 35.7.
The damage done at the hoist shaft was terrific as undoubtedly this shaft was in the direct line of the explosion. The man-shaft was also badly damaged. It is safe to state that only about fifty percent of the force that was exerted at the hoist shaft was exerted at man-shaft and possibly ten per cent at air shaft. The greatest destruction at any point was that at the hoist shaft, but this is no indication that the explosion happened at that point, for, generally speaking, the point of origin shows the least physical destruction. This, of course, would be determined by the source and cause of ignition. If high explosives, such as caused the explosion at the Summerless mine, were responsible, then there would be a great shattering force, the effects of which would be easily noticed. An explosion does not attain high velocity nor build up high pressure until it has traveled nearly two hundred feet. This, however, is determined by the amount of dust it has to feed upon, also the fineness of the dust, etc.
In demonstration work, velocities of three thousand feet per second have been recorded and, judging from the destruction of this mine and the extent of development, it is safe to assume that the velocity of the flame of this explosion traveled not less than three thousand feet per second, and possibly developed a pressure of not less than one hundred and forty pounds to the square inch; but this depends upon the rapidity of the combustion of the dust and the percentage that is finer than twenty mesh, as dust coarser than twenty mesh will not ignite. The finer the dust, the easier it is to ignite and the more violent the explosion.
The explosion wave travels in conic shape, the apex being at or near the center of the opening through which the flame is traveling, and it is the movement of the flame and hot gases that constitutes the chemical reaction. Preceding the explosion wave is the shock wave which stirs up the fine dust, destroying doors and knocking out timbers.
In this mine there were a great number of steel beams with lagging, which served as shelves for fine dry dust that had been picked up and deposited by the air current. These acted as boosters and in some cases, where there were great quantities of lagging, it would show the effects of this boosting by the timbers being blown in both directions. This condition, however, was only local. The explosion was very confusing and hard to trace, as material which had been blown in one direction by the explosion wave had been picked up and hurled in the opposite direction by the retonation wave, which is caused by the high pressure built up by an advancing explosion. This pressure becomes so great that the gases in the rear of an explosion are driven back with a high velocity, and the back lash or recoil, which results from the cooling of the hot burning gases, is also responsible for the carrying of material in the opposite direction from that of the explosion.
At some places in the mine the coking and signs of intense flame and heat of longer duration were very marked. This, no doubt, was caused by slow combustion, which is the slow burning of dust and gases. The points where these conditions prevailed were widely separated and at or close to the working face.
This company was making every effort to safeguard its men and property, and it spared no money that this might be accomplished, yet a disaster of this magnitude occurred and, regardless of the cause of the explosion or the point of origin, the fact remains that the explosion was general, proving the ineffectiveness of water as a preventative for coal cust explosions. However, this does not apply to mines that are naturally wet, but, where it is necessary to sprinkle or humidify mines, they will be much better protected by rock dusting which is as economical and far more effective.
Prepared by
Robert M. Lambie, Chief
Department of Mines
Charleston, West Virginia.
May 16, 1925.