NSW’s resources regulator recently issued a safety alert for the state’s mining industry following a series of planned inspections at various mines in Lightning Ridge to assess hazards associated with fall of ground.
The inspections assessed if mine operators had identified fall of ground hazards, carried out an appropriate risk assessment for the hazards, and identified and implemented risk controls to ensure the safety of workers.
The alert said that mine operators have an obligation to have a safety management system that sets out the systems, procedures, plans and other control measures that will be used to control any risks to health and safety associated with ground or strata failure.
Following the planned inspections, the operator of an underground mining site in Lightning Ridge subsequently restricted an area with insufficient roof support from workers, and the area, which had mining equipment in it, was taped off with orange barrier tape creating a ‘no entry’ zone.
Inspectors from the regulator concluded that the mine had insufficient pillar support in certain areas due to an unexpected level of pillar extraction, with no secondary support as recommended in the regulator’s guidance material NSW Opal Mining safety guidelines.
An improvement notice and a prohibition notice were issued to the mine operator. The improvement notice directed the mine operator to install secondary support, while the prohibition notice prohibited any person from going into the restricted area unless it was for the purpose of installing secondary support.
The safety alert made a number of recommendations:
Ensure that there is adequate support, both primary and secondary at the shaft bottom. This is the primary means of escape and it must remain secure.
Before excavating a drive, it is essential to conduct checks with adjoining mining leases to assess if any other excavation work will affect your roof and wall stability. Consideration will then need to be given as to the type and amount of support needed.
Secondary support should be installed at the time an opening is created, such as a drive.
Drive widths are generally a maximum of 1.8 metres. A drive wider than this will require secondary support. In narrower drives secondary support will be essential if rock strength is affected by rock material, discontinuities and nearby workings.
Regular checks must be carried out to assess the condition of roofs, walls and supports. Fretting of pillars indicates that the pillar is taking weight or is drying out, and should be meshed and made secure. Props need to be checked for looseness, rot and damage, and additional supports installed where needed.