In the evening of October 13, 1954, an outburst occurred in the deepest part of the Collinsville State Mine about one and a half kilometres from the entrance of the No. 1 tunnel. Seven men were killed when 900 tonnes of coal and stone was dislodged and blown 30 metres up the heading
On this aspect of the term, which is the most important factor for consideration—i.e., the possibility of future outbursts of CO2—we realise that it will be impossible to devise any method which would eliminate such possibility.
It is essential, therefore, that the operation of the mine be such that, if such outburst does occur, the employees will be, as far as is reasonably practicable, adequately protected.
The authorities which we have cited, particularly the more recent ones, indicate that boring ahead is of no practical advantage except to discover if there is trouble ahead. It does not in itself provide any safeguard against an outburst nor enable the gas to effectively bleed off.
We think that, if the precautions which we recommend are adopted, such precautions will ensure a reasonable degree of safety in the operation of the mine.
We recommend that in all main development places in addition to places known to be approaching a proved fault, dyke, or sill, that grunching with mini-second delay detonators should be resorted to, with no employees allowed within the area which would be affected in the event of an outburst, and the person engaged in the operation of shot-firing to be no closer than 300 ft. on the intake side when the shots are fired.
We are of the opinion that inducer shot-firing, as suggested, will provide maximum safety for employees by including outbursts when employees are absent from any area likely to be affected in the event of an outburst.
These precautions are framed on the basis that, when a known fault, dyke or sill is being approached or when virgin country is being developed by the driving of main development places, trouble is assumed to be ahead.
We further recommend that as much of the shooting of all places, as is reasonably practicable, should be done at a time when the least number of employees are in the mine and that as many shots as possible should be fired at the one time whether by inducer or simultaneous shot-firing.
These recommendations are made to provide maximum safety for the employees and are made after the most careful consideration of which we are capable, of various authorities and other matter which have been placed before us and which we have ourselves discovered.