On the Causes of and Circumstances attending the Shaft Accident which occurred at the Bilsthorpe Colliery Sinking on the 1st March, 1927. To Mines Department, Dean Stanley Street, Millbank, S.W.1. 25th July, 1927. Colonel the Right Hon. G. R. LANE FOX, M.P., SIR, Secretary for Mines. In accordance with your directions I have held a formal investigation under Section 83 of the Coal Mines Act, 1911, into the causes and circumstances of the accident which occurred in the No. 1 Shaft of the Bilsthorpe Colliery Sinking, situated at Bilsthorpe in the County of Nottingham, on the 1st March, 1927, causing the deaths of fourteen persons and injury to three others. I have now the honour to report as follows: My inquiry was held on the 22nd and 23rd June, 1927, in the Guildhall, Nottingham, excellent accommodation and every facility being available through the kindness of the Town Clerk and his officials, to whom I am greatly indebted. The representatives of the interested parties were as follows:Mr. J. R. Felton, O.B. E., H.M. II. DESCRIPTION OF THE SINKING AND EQUIPMENT. The site of this new winning is about 7 miles due east of Mansfield, Nottinghamshire. The sinking of two shafts, each to be of 20 feet 2 inches diameter within the lining, was commenced in July, 1925. Coal has not yet been reached. The sinking arrangements at both shafts were the same. On 1st March the No. 1 shaft was down to a depth of 278 yards (20 yards more than the No. 2 shaft) and was lined with concrete to a depth of 253 yards. Below this lining the shaft sides were supported by 4-inches by 1-inch iron rings set about 4 feet apart, behind which backing sheets of corrugated iron were held tight by wedges. The lowest ring was about five feet from the bottom of the shaft. Water was met at a depth of 63 feet and below this point cement was injected into the surrounding strata to keep out of the actual pit as much of the water as possible. As sinking proceeded the shaft was lined with concrete of 16 inches thickness at the top gradually increasing with the depth to 25 inches at the last completed length. A steam pump was used for dealing with the inflow of water to 'a depth of 150 feet when it was replaced by a Sulzer electrically driven centrifugal pump. This latter pump, designed to deliver 1,000 gallons of water per minute against a head of 1,040 feet, was driven by a 500 h.p. three phase motor, the voltage being 2,000 to 2,200. The combined motor and pump unit weighed 14 tons, and was suspended in the shaft by means of a steel rope fixed at one end to the headgear, passing down the shaft and under a pulley on the pump unit, and thence back up to the drum of a capstan engine by which the whole was lowered or raised as required. The delivery column or rising main consisted of pipes of weldless steel of 5 gauge thickness and 8-inches internal diameter with loose cast steel flanges, each joint being secured by eight 3-inch diameter bolts through the flanges. The pipes were in lengths varying from 14 to 18 feet. The main was retained in a vertical position by means of clamps of oak attached tightly to each alternate length of pipe with a hole at each end through which the pump suspension rope passed, the holes being large enough to allow the rope to move freely through the clamps when the pump was raised or lowered. The foregoing particulars will be more easily understood by reference to Plate 1 which shows the method of supporting the shaft sides and suspending the pump and the rising main. The electric cable which supplied power to the pump passed through another hole at one side of each pipe clamp and was there held by small special clamps-see Plate 2. At the time of the accident the total weight of the pump unit, rising main full of water, clamps, cables and suspension rope was 40.29 tons. The suspension rope was 7 inches circumference of best acid grade steel wire, having an actual breaking strain of 161 tons. The walling scaffold was suspended on two other ropes attached to separate capstan drums and at the time of the accident was 79 feet above the shaft bottom. III. OCCURRENCE OF THE ACCIDENT. 66 At about 7 p.m. on the 28th February a round of sumping shots had been fired and so far as could be judged had done its work satisfactorily. From that time onwards the work of filling out the ground broken by the shots proceeded in the ordinary way and the pump, which had been raised the usual 18-20 feet while the shots were fired and afterwards lowered into the normal position, worked smoothly and without intermission. The amount of water to be dealt with at this time averaged from 12 to 15,000 gallons per hour. The pump was lowered a further few inches from time to time as the bottom was cleared of debris, the last lowering before the accident being at about 1.30 a.m. on the 1st March. There were 21 men working in the shaft and at about 2 a.m. they began to go to the surface in relays for their " snap." When the third batch of men, five including the pump attendant, left the shaft bottom everything appeared to be in order, but before they had reached the top the pump jacked (began to draw air) and on a signal from the bottom the electric current was shut off at the surface. Having arrived at the top the pumpman decided to go back to restart the pump and proceeded down in the hoppit along with a load of men who had "snapped." The hoppit had been lowered to the "steady," i.e., the point about 18 feet from the bottom where it is stopped until a further signal is given before it is lowered right on to the bottom, when the men on the surface heard a crash, and the greater part of the rising main (from the surface to a point 169 yards down the shaft) collapsed into the bottom of the sinking. Simultaneously the electric cable drum was jerked from its foundation and pulled over towards the shaft, the cable itself being damaged some 150 to 160 yards down the shaft but not broken. The pump suspension rope was undamaged. The engineman felt a jerk on the winding rope and tried to raise the hoppit but found that it was held down by the debris. IV. RESCUE AND RECOVERY WORK. The hoppit being held at the bottom, the winding rope was cut at the surface, recapped, and a new hoppit fitted. This was lowered part way down the shaft until it came to the lower part of the rising main which it was found, although still standing, was leaning across the shaft so as to prevent any further lowering As shouts could be heard from the shaft bottom another rope was procured and lowered from the hoppit with a safety belt on the end. 278 A 2 II. DESCRIPTION OF THE SINKING AND EQUIPMENT. The site of this new winning is about 7 miles due east of Mansfield, Nottinghamshire. The sinking of two shafts, each to be of 20 feet 2 inches diameter within the lining, was commenced in July, 1925. Coal has not yet been reached. The sinking arrangements at both shafts were the same. On 1st March the No. 1 shaft was down to a depth of 278 yards (20 yards more than the No. 2 shaft) and was lined with concrete to a depth of 253 yards. Below this lining the shaft sides were supported by 4-inches by 1-inch iron rings set about 4 feet apart, behind which backing sheets of corrugated iron were held tight by wedges. The lowest ring was about five feet from the bottom of the shaft. Water was met at a depth of 63 feet and below this point cement was injected into the surrounding strata to keep out of the actual pit as much of the water as possible. As sinking proceeded the shaft was lined with concrete of 16 inches thickness at the top gradually increasing with the depth to 25 inches at the last completed length. A steam pump was used for dealing with the inflow of water to 'a depth of 150 feet when it was replaced by a Sulzer electrically driven centrifugal pump. This latter pump, designed to deliver 1,000 gallons of water per minute against a head of 1,040 feet, was driven by a 500 h.p. three phase motor, the voltage being 2,000 to 2,200. The combined motor and pump unit weighed 14 tons, and was suspended in the shaft by means of a steel rope fixed at one end to the headgear, passing down the shaft and under a pulley on the pump unit, and thence back up to the drum of a capstan engine by which the whole was lowered or raised as required. The delivery column or rising main consisted of pipes of weldless steel of 5 gauge thickness and 8-inches internal diameter with loose cast steel flanges, each joint being secured by eight 3-inch diameter bolts through the flanges. The pipes were in lengths varying from 14 to 18 feet. The main was retained in a vertical position by means of clamps of oak attached tightly to each alternate length of pipe with a hole at each end through which the pump suspension rope passed, the holes being large enough to allow the rope to move freely through the clamps when the pump was raised or lowered. The foregoing particulars will be more easily understood by reference to Plate 1 which shows the method of supporting the shaft sides and suspending the pump and the rising main. The electric cable which supplied power to the pump passed through another hole at one side of each pipe clamp and was there held by small special clamps-see Plate 2. At the time of the accident the total weight of the pump unit, rising main full of water, clamps, cables and suspension rope was 40.29 tons. The suspension rope was 7 inches circumference of |