The Burngrange Shale Mine was situated about 16 miles south-west of Edinburgh in the parish of West Calder in the County of Midlothian.
It was the property of Young’s Paraffin Light and Mineral Oil Co. Ltd which was a subsidiary of Scottish Oils Ltd.
It was one of 12 mines working oil shales in Midlothian and West Lothian.
A disaster of this magnitude in a shale mine is unusual. Oil shale had been worked in the neighbourhood since 1858 on a large scale and by 1865 there were about 120 works processing the shales from the Lothian or cannel shales of the coal measures.
The oil shales of the Lothians occurred in the Calciferous Sandstone Series near the base of the Carboniferous System and were a System and constituted a local development which was peculiar to the West Lothian, Midlothian and the adjacent portions in Fife and Lanark. The annual output of shale from the mines owned by six different operating companies reached a maximum of about three quarters of a million tons in 1913. All the companies were brought under one management in 1919 by the formation of Scottish Oils Limited. From 1913, for many reasons mainly arising from the 1914-18 and 1939-45 wars there had been a decline in the output and in 1946 the annual output was just over a third of a million tons.
The Burngrange Mine was relatively new, having stared production in 1936. There were two vertical shafts each 14 feet in diameter and brick lined throughout. The No.1 shaft was use for winding men, minerals and other materials and the No.2 shaft was used for ventilation and pumping. Both shafts were sunk to a depth of 486 feet to work the Dunnet Shale Seam which varied in thickness from 9 to 12 feet. The dip of the seam in the No.2 District of the mine was variable averaging 1 in 5 in a north-westerly direction. The mine was ventilated by a double inlet Sirocco exhausting fan passing about 100,000 cubic feet of air per minute at a water gauge of 0.95 inches. All the workings were in the Dunnet Seam and the average daily output of shale over two winding shifts was 600 tons. The number of men employed was approximately 29 on the surface and 176 underground, a total of 205.
The shale was worked by stoop and room method and the size of the stoops varied according to depth but in the area affected by the explosion, the stoops were formed approximately 150 feet by 110 feet by driving rooms 12 feet wide and 9 feet high on a level course and at right angles to them. Where the seam exceeded 9 feet in height, the top shale was left to form a roof. In the second working, when the stoops had been extracted, splits were driven through each stoop to form small pillars which were then extracted by taking off lifts 12 feet wide and the full height of the seam. Pillar extraction was generally arranged to form and maintain a main roof line fracture at an angle of about 45 degrees to the levels.
The disaster was confined to one ventilating split which ventilated part of the No. 3 district and the whole of the No.2 District which comprised two sections of workings in one of which the pillars were being extracted and in another to the east of it large stoops were being spit into small pillars. The area covered a full three acres of shale had been extracted to the north east of the middle dook which was known as 40 H.P. dook and referred to here as No.2 Dook. Extraction from these stoops in this area commenced in 1945 and was being continued on the east side of the area. From the inbye ends of Nos. 10 to 14 Levels and to the east of the stoop area, the stoops were being divided into pillars. These pillars were left to avoid subsidence at the surface which could damage a housing scheme. It was in these sections that all but one of the 15 victims of the disaster lost their lives. Before the slitting of the stoops, prior to extraction, work was also proceeding on the No.3 District on the outbye or west side of the extraction area.
The shale was got by blasting and was hand filled by the miners into 20 cwt. ‘hutches’ which were then drawn for a short distance by drawers to a mechanical haulage. The hutches were then hauled by diesel locomotive and main haulage rope to the shaft bottom. Compressed gunpowder was the explosive that was used, fired by a fuse. The holes for the blasting were bored by electrically operated drills and all the machinery that was used underground was driven by electricity.
A mixed system of lighting, both open lights and safety lamps were used underground. Firedamp was a rare occurrence but it had been found before and in consequence certain precautions were taken. It was customary for the miner working at the face to use an approved electric safety cap lamp and to be provided with a flame safety lamp which was hung near the working face. The drawers, who carried these flame lamps in and out of the mine and the other outbye workmen used acetylene cap lamps. Rules were posted in the mine regarding the use of safety lamps as follows-
“FACEMEN IN CHARGE OF PLACES SHALL USE ELECTRIC CAP LAMPS.
FLAME SAFETY LAMPS SHALL BE KEPT IN WORKING PLACES.
BEFORE ENTERING PLACES AT THE COMMENCEMENT OF WORK AND
BEFORE AND AFTER SHOT FIRING, THE FACEMEN SHALL TEST FOR THE PRESENCE OF GAS.”
The mine worked under the Coal Mines Act 1911 and was under the daily supervision of a certificated manager Mr. John Brownlie McArthur and was assisted by an undermanager Mr. Archibald Gibb Russell. Supervising them was Mr. John Caldwell and Robert Crichton, General Mines Manager and Managing Director respectively of Scottish Oils Limited. All were holders of first class certificates of competency in mine management.