Many ore bodies are either extensions of known mine ore bodies or are close to old mine workings. Underground exploration, often by entering abandoned workings, may be needed in both situations. Entry into old mines presents unusual and severe hazards, which must be thoroughly assessed before attempting to go underground.
Entry should be strongly discouraged because of the dangers. Inexperienced people should not take risks just
because they want to have ‘a quick look around underground’. Extensive preparation and planning is needed before considering entering old mines. This may include:
• discussions with previous owners or employees to determine the extent and condition of the workings
• visits to the Department Natural Resources and Mines to obtain old plans or reports, and seek advice from experts including inspectors of mines
• careful study of the surface for indications of old shafts, stopes and underground collapses (this should be carried out even when exploring only on the surface of old mines)
• employment of competent experienced underground miners.
Please note that you should not try to enter old shafts, either vertical or inclined, until they have been examined and made safe by a competent experienced shaft worker. If preliminary underground exploration cannot be avoided, great caution must be exercised before and during entry. Hazards may be encountered from the nature of the rock and the mining methods, and from the hidden dangers of poor ventilation. Under no circumstances should anyone venture underground alone. Physical dangers may include:
• unsupported bad ground which may collapse at any time
• ground support which has deteriorated but appears sound, giving a false sense of security
• rotten timbers in shafts which will break under any load or weight
An accident waiting to happen?
• rotten timber supports which may allow rock falls, if disturbed
• corroded steel supports and steel rungs of old ladders
• open passes in drives which may not be safely covered
• hung-up ore passes or shrinkage stopes
• deep water and flooded workings
• unknown dangers both above and underfoot
• poisonous snakes and spiders
• diseases from bats, bat droppings and mould.
Hidden dangers in the underground atmosphere caused by poor ventilation may include:
• oxygen deficiency caused by oxidation of ores or timbers. Pockets of oxygen deficient atmosphere can exist in any mine and could cause the sudden collapse of an unwary person
• excess carbon dioxide, also caused by oxidation of carbonaceous matter and frequently associated with oxygen deficiency
• hydrogen sulphide, sulphur dioxide and other poisonous gases
• flammable gases such as methane
• alterations to underground ventilation from pressure and temperature changes during the day, and with seasonal changes.
Field crews going underground should be equipped with:
• hard hats, lamps (and spares), scaling bars, spray paint (for marking unsafe ground, route taken, etc.), tape, and safety lines
• oxygen detector, flammable and toxic gas detectors, and possibly oxygen selfrescuers
• any available relevant plans.
Important points to consider when going underground are as follows:
• Undertake initial investigations. Examine ground conditions, ventilation and presence of water, and advance when safe to do so.
• Always check back to the entrance at frequent intervals to get your bearings.
• Always make sure that at least two crew members stay on the surface with suitable communications equipment to raise the alarm, should the party not return within a specified time.
• Under no circumstances should any person continue exploration near areas found to have inadequate air or toxic gases.
• Old shafts, adits or other workings which may pose a hazard to field crews or contractors working in the area should be fenced or roped off.