OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 36 Mining

Section 701 Mine outlets

Subsection 701(1)

The requirement for at least two outlets or emergency exits is the same for mines and many other workplaces. Underground mines are more restrictive and more prone to emergency situations than buildings.

These two outlets generally form part of the ventilation system in underground mines by providing fresh air to working areas through one outlet and returning used air through the other. The underground workings include cross cuts driven at certain intervals to provide alternate escape routes as well as pathways for ventilation tubing. One of the outlets often serves as a conveyor gallery for transporting coal out of the mine.

Subsection 701(2)

The availability of a voice communication system, in case of emergency, allows workers to communicate their presence directly to the command centre.

Subsection 701(2.1)

Mine outlets are typically either vertical shafts or inclined slopes. In an emergency such as a fire or explosion, two mine outlets located too close to one another may both be damaged, thus potentially trapping workers underground. A safe separation distance for mine outlets must be maintained for all foreseeable emergencies. The employer must ensure that the mine openings or outlets are at a safe distance from one another by ensuring the designs are certified by a professional engineer. In the event of an emergency, at least one opening will allow worker egress.

The safe separation distance will vary from mine site to mine site and will depend upon many factors e.g. geology – the type of surrounding rock mass, its structure and properties geotechnology – the interrelationship and stability of rock mass and soils and engineered structures such as shafts, tunnels and ground slopes; and physical factors – such as the relative geometry, shape and size of the structures involved.

Subsection 701(3)

Exploration and early development work for a mine are exempt from the requirement of subsection 701(1) for practical reasons. However, the employer must ensure worker safety by conducting site hazard assessments as required by Part 2.

Subsection 701(4)

This subsection recognizes that under some circumstances, such as in the development of new areas, workers must work in a “single-entry” or blind heading, tunnel, roadway or shaft. In such circumstances, especially in the sinking or vertical shafts, working space is restricted and thus the number of workers allowed in the mine working must be limited. In such cases this limit is set at a  maximum of nine at any one time.

It is also recognized that in an emergency, should there be nine persons already in the working area, it may be impossible for some of them to come out to allow emergency response and mine rescue personnel in. This subsection allows such emergency personnel to enter in sufficient numbers to safely conduct their work. In the absence of the extra outlet, monitoring and control take on higher priorities to maintain required safety levels.