The Walton colliery was formerly known as the Sharlston West and was near Wakefield in the West Riding of Yorkshire. It was a safety lamp mine that employed 1,285 men underground and 298 on the surface with a daily output of 2,200 tons from the Top Haigh Moor, the Low Haigh Moor, the Kent Thick and the Birkwood or Lidgett Seams. About half the output came from the Top Haigh Moor seam.
The 10 East District lay in the Top Haigh Moor Seam on the east side of the South West Haulage Road connecting to the No. 2 shaft to the Haw Park shaft. The explosion took place in the 5’s Unit. At the colliery, the Top Haigh Moor Seam was worked in the 10 East District. The two coals were separated by a band of hard fireclay about 7 feet thick and the Top Haigh Moor seam was overlain with a thick bed of strong sandstone.
The accident occurred about 460 yards from the surface. Faults had been encountered in the 10 East District in 1955 and further developments had driven two roads, 22 yards apart, through the faulted area to develop a longwall face, 40 yards long which was known as the 10 East 1’s. This was advanced to the boundary and stopped on the 23rd July 1958 leaving solid coal on each side.
Coal to the south of the 10 East Trunk Conveyor Road was intended to be worked by a double until longwall face about 280 yards long which was to advance to the south. In the general plan of operations a face, the second to be worked from 1’s Development, was taken some 20 yards wide for a distance of about 40 yards to the south. The western side of the new development was then worked as a face 40 yards wide which advanced for about 100 yards to the west to connect with a heading known as 5’s New Loader Gate, which was being at the same time to the south from a point further outbye on 10 East Trunk Conveyor Road. The face was then to be continued westwards so that eventually a double unit face about 280 yards long would be advanced to the south, after 2’s Drift had afforded a new return airway for the district.
At the time of the explosion the 40 yards face, 5’s Unit, had advanced about 97 yards. A small further advance, which would have been made in a few days but for the disaster, would have brought it to the position where it could have been stopped to await the connection of the New Loader Gate. At the north end of the working face the roof had been ripped to form a road supported by steel arch girders 12 feet wide and 8 feet high. This road was known as the 5’s Intake Gate and it was intended to become the return airway for the western until of the 280 yards face when it was finally developed. It was connected to 10 East Trunk Conveyor Road by means of 5’s Intake Slit, which was a passage some 37 feet long that had originally been made about 6 feet wide and the height of the seam.
At the left end of the 40 yards face, a passageway of seam height and 12 feet wide was being left so that it could eventually become the left side of the main longwall face to the south. This passage was known as the 5’s Ribside and was formed by the coal and a pack about 12 feet wide. At the outbye end of this pack, there was a gap about 9 yards long which had been left as an access to the waste. This had not been closed but in which thin slabs of stone had fallen from time to time. A bottom loading belt conveyor on 5’s Belt Return Gate. This conveyor discharged on the 10 East Trunk Conveyor at the same transfer point as the stone loading conveyor from 2’s Drift.
In the planned system of ventilation air entered 10 East District from the South West Haulage Road, partly along the 10 East Main Haulage Road and partly from a second source to and from the 5’s Unit. This course was on conventional lines, but because of the heavy leakage losses beyond the loading point only a small proportion of the 12 to 16,000 cubic feet of air per minute available there reached the face of the 5’s Unit.
A few days before the accident, a direct connection had been made by means of a scour driven through the waste between 5’s intake and 5’s Return but sheets had been erected in it to prevent a short circuit of the ventilation there.
The coal on the 5’s Unit was undercut by an electrically driven coal cutting machine, blasted and hand loaded on to the face conveyor. Coal was filled on the morning and afternoon shifts. The Intake gate ripping was advanced on the afternoon and night shifts and the stone pack on the Ribside was advanced on the night shift with stone from the Intake ripping. There had been difficulty in achieving the management’s objective of obtaining two cuts in each 24 hours and in order to maintain work in the break of 12.30 to 1.30 p.m. between the day and the afternoon shifts, two coal cutting machine men and an overman worked a supplementary shift from 8 a.m. to 3.30 p.m.
On the afternoon shift of the 21st. April, 1959, the day before the disaster, coal had been prepared for filling and the 5’s Intake Gate ripping was advanced. On the night shift some of the colliers were employed in squaring out the right hand corner of the face and the rippers for the Intake Gate, having no work to do there, spent the shift at the new connection where about 12 shots were fired in the stone to enlarge the holing.