Wakefield, Yorkshire. 21st March 1973
The Lofthouse Colliery was in the North Area of the National Coal Board and was about 2 miles to the north of Wakefield on the western fringe of the workable coalfield.
Production began at the colliery in 1877 and at the time of the accident the colliery produced 18,500 tons of saleable coal per week and employed 837 men below ground and 207 at the surface.
There were four shafts.
- A was the downcast and was 18 feet 6 inches in diameter
- B the upcast was 15 feet in diameter was at Lofthouse
- Silkstone which was a downcast was at Wrenthorpe
- Beeston which was upcast of 14 feet in diameter was also at Wrenthorpe about one and three quarter miles to the south.
The Silkstone shaft had winding equipment but there were no winding facilities at the Beeston shaft. At the top of the B shaft there were three Aerex fans in parallel which extracted 180,000 cubic feet of air per minute at 7 inches water gauge. A Keith Blackman centrifugal fan extracted 60,00 cubic feet per minute at 3.2 inches water gauge at the Beeston shaft at Wrenthorpe.
Electric cap lamps were in general use with flame safety lamps issued and firedamp detectors. Certain officials were also issued with methanometers. The officials holding statutory appointments at the time of the accident were,
- Mr. T, Wright, Acting Area Director,
- M.r G. Hayes, Deputy Director (Mining)
- Mr. W. Forrest, Chief Mining Engineer
- Mr. R.P. Hollis Deputy Chief Mining Engineer (Mine Planning and Surveying)
- Mr. T. Donnelly, Production Manager
- Mr. T. Mapplebeck, colliery manager.
The coal was won from longwall advancing mechanised faces and the seams that were worked in descending order were:-
- Flockton Thin which had three working faces
- Eleven Yards with one working face
- Beeston which had two working faces.
Development was taking place in the Blocking Bed seam which lay between the Eleven Yards and the Beeston seams. Very little water was pumped from the mine. The main intake at the Lofthouse A and B shafts were from the old Haigh Moor workings and was between 160 and 230 gallons per minute depending on the season. At the Wrenthorpe shafts there was a well shaft 63 feet deep, from which 33 to 35 gallons of water per minute were pumped. The make of water in the main shafts at Wrenthorpe was only
15 gallons per minute pumped from the Silkstone pit bottom.
The south 9B district was in the Flockton Thin seam to the west of the South 4 loader gate and the face was 5,600 yards from the Lofthouse pit bottom. The Flockton seam was
34 inches thick which included a dirt band three inches thick. The roof was of a medium grey shaley mudstone and the floor was also of mudstone. The face lay about 220 yards below the surface and two seams were worked above it 120 to 130 years before. They were the Gawthorpe, (Warren House) at a depth of 50 yards and the Top Haigh Moor at 120 yards. The Silkstone seam was about 80 yards below the Flockton Thin and was worked around 1914.
Access to the South 9B district from South 4 loader gate was gained by a cross measure intake drift dipping 1 in 6 through faults of 48 feet vertical displacement. A 216 yards long single unit conveyor face was formed in the seam, with the return airway connected by an overcast to a roadway leading to the Wrenthorpe shafts, a slit at the air crossing, with two wooden air lock doors, provided a connection between intake and return.
Production commenced in December 1971 and the coal was won on three shifts per day by a double ended conveyor mounted trepanner taking full thickness of the seam and 2 inches of dirt from the floor. The trepanner took a 26 inches web and the average weekly advance was 20 yards and the face had got to a rise at 1 in 24 for a total of 1,060 yards when the inrush occurred. At the main gate of the face an advancing heading 4 feet 6 inches high was taken 18 to 25 feet ahead of the general face line and a stable at the same height extended 12 feet along the face. At the tail gate there was an 8 feet long stable at seam height. Rigid bars and hydraulic props were used in the roadhead areas and powered supports throughout the face.
Both gates were formed by conventional ripping and packing, with the main gate supported by arch girders 10 feet wide and 8 feet high set at 3 feet intervals and the tail gate similarly supported by 8 feet wide by 7 feet high steel arches. The district was ventilated by a separate split giving 11,700 cubic feet of air per minute on the face.
Methane drainage was installed from the tail gate with holes 120 feet long spaced at
120 feet intervals at right angles to the gate and inclined at 45 degrees over the waste. The methane content at the statutory measuring point was about 0.3 per cent. The amount of water in the district was small and systematic pumping was necessary.
Although there was a small fault on the face, 80 yards from the main gate and weighted breaks were evident from time to time, the roof was well controlled by five legged powered supports.