Lesson 11 – Underground Power Failure

DEFINITION OF A POWER FAILURE:

An interruption in the electrical power supply to the mine or any area of the mine, which will be or is likely to be of sufficient duration to constitute a hazard to any person underground at that time.

Duties of any person underground who suspects that a major power failure has occurred:

• Remove all persons in his charge to a through airway and leave them in the charge of a Team Leader, Crew Supervisor or other responsible person.
• Phone Banksman/Onsetter/Hoist Driver to determine if a Major Power Failure has occurred or whether the power failure is isolated to a section of the mine.
• If the power has failed in only a section of the mine, report to the nearest electrician or electrical foreman and notify the Shiftboss or Mine Overseer.

If indications are that:

• Power will be off for less than 2 hours, leave persons in through airway, maintain contact with Mine Overseer or his deputy for further instructions.
• In the event that power will be off for 2 to 6 hours, the Mine Overseer/Manager Mining will give instructions to remove all persons from the workings to the shaft stations.
• In the event that power is likely to be off for more than 6 hours, the action to be taken will be decided on by the Mine Overseer and Engineer in consultation with the Manager Mining.

MAJOR POWER FAILURE:

The following procedure will be adhered to.

Power failure preparedness.

• Ensure that all backup emergency equipment is in good operational condition.
• Diesel powered generators and fans (Fairview) must be tested regularly and tests should be recorded.
• Ensure that diesel storage is sufficient
• Ensure that communications systems are supplied by a backup UPS and tested.
• Determine the sufficiency and requirements of a backup system in case of emergency

Immediate Supervisor:

Notify:

• Manager Mining
• Engineer and Staff
• Ventilation Superintendent
• Mine Overseer
• Safety Officer
• Medical Assistance/Ambulance if required
• HR Practitioner

Determine: 

• Whether persons are trapped
• Reason for power failure
• Possible duration of failure
• Flooding
• Ventilation

Duties:

Persons in charge underground:

• Make sure all persons are in through ventilation.
• Withdraw persons from lower levels, which could be affected by flooding.
• Erect coffer dams where required.
• Maintain order underground.
• Conserve light once shaft stations have been reached, minimum number of caplamps should be left burning.

Engineer:

• Get power supply restored as soon as possible.
• Determine whether persons are trapped in vertical shaft conveyances. Determine specific positions of conveyances in shafts, number of people in conveyances etc. Give detailed instructions when permitting the use of standby equipment or when conveyances have to be moved in order to remove people.

Mine Overseer:

• Ensure that all service water supply columns are closed off.
• Ensure that drain water is kept away from shaft and pump stations by closing off coffer dams.
• Maintain contact with persons in charge underground to ensure that all persons are moved to through ventilation, e.g. shaft stations and to maintain order and discipline.
• Issue specific instructions to ensure clearance of each level through the specific indicated routes, should evacuation be decided upon.

Environmental Superintendent:

• Advise Manager: Mining/Mine Overseer of any measures to improve natural flow of ventilation, e.g. opening of certain doors, power failure simulations to all sections.

HR Practitioner:

• Ensure that relevant officials have been alerted.
• Ensure that telephone is manned continuously.
• Maintain a record of al employees arriving on surface.
• Arrange for food etc. if required.

Chief Safety Officer:

• Be available at all times to assist Manager: Mining/Mine Overseer.