Gresford Disaster - Background

Background

Work began sinking the pit at Gresford in 1908 by Westminster and United Collieries Group. Two shafts were sunk 50 yards (46 m) apart: the Dennis (named after the industrialist Dennis family of Ruabon who were the pit owners) and the Martin. Work was completed in 1911. The mine was one of the deepest in the Denbighshire Coalfield with the Dennis shaft reaching depths of about 2,264 feet (690 m) and the Martin shaft about 2,252 feet (686 m).

By 1934, 2,200 coal miners were employed at the colliery, with 1,850 working underground and 350 on the surface. Three coal seams were worked at Gresford:

1. Crank (Martin), a 3 ft (0.91 m) seam producing high-quality household coal. No firedamp.
2. Brassey (Martin, part Dennis), a 4 ft (1.2 m) to 12 ft (3.7 m) seam delivering harder 'steam' coal for commercial use. No firedamp.
3. Main (Dennis), a 7 ft (2.1 m) seam that produced softer industrial coal. But very prevalent to firedamp.

The explosion would occur within the Main seam of Dennis. This section, which began more than 1.3 miles (2.1 km) from the shaft bottom, was mined down a shallow gradient. Dennis was divided into six "districts": 20's, 61's, 109's, 14's and 29's. The sixth district was a very deep area known collectively as the "95's and 24's". All the districts in Dennis were worked by the longwall system where the coal face was mined in single blocks. Most districts in the Dennis section were mechanised except 20's and 61's, which were still worked by hand, because they were furthest from the main shaft (approx 2.75 miles (4.43 km)).

Conditions in the mine prior to the explosion were presented into evidence at the inquiry into the disaster. Firstly underground mine ventilation in some districts of Dennis were probably inadequate, in particular, the 14's and 29's districts were notorious for poor air quality. The main return airway for the 109's, 14's and 29's districts was said to be 4 feet (1.2 m) by 4 feet (1.2 m) and far too small to provide adequate ventilation. Secondly working conditions in the 2,600 feet (790 m) deep 95's and 24's district was always uncomfortably hot. Thirdly there were also numerous breaches of safety regulations such as the firing of explosive charges in 14's district and the failure to take of dust samples.

The disaster inquiry was told one of the pit deputies (whose job was in theory to oversee the safety of the workings) admitted that he also carried out shotfiring during his shifts, in addition to his other duties. It was revealed that he fired more charges during his shift than a full-time shotfirer could have safely carried out. Furthermore the colliery had made an operating loss in 1933, and the pit manager, William Bonsall, had been under pressure from the Dennis family to increase profitability. He admitted he had spent little time in the Dennis section of the pit in the months before the disaster, as he was overseeing the installation of new machinery in the "Slant", an area in the south-eastern part of the Martin section of the mine.