Background
Mines are designed, constructed and maintained to be safe while in operation. However, once work ceases, mines can fall into disrepair and become increasingly hazardous. Some mines may not be active and are under 'care and maintenance' or 'suspension' while others remain undocumented or unknown.
Unoccupied mines can present a serious hazard to anyone participating in recreational activities such as swimming, abseiling, rock climbing, hiking, dirt biking, using water-going equipment or driving offroad. There have been several fatal accidents after unauthorised access (whether intentional or inadvertent) of unoccupied mines by members of the public for recreational purposes.
Summary of hazard
Many hazards associated with unoccupied mine sites may not be obvious, but can pose serious risks to anyone entering. Hazards include:
- water (e.g. low temperatures, high alkalinity, high acidity, microbial contamination)
- rockfalls and roof collapses [e.g. unstable highwalls, rotting timbers and unstable rock formations in horizontal mine openings (adits)]
- hidden vertical shafts and edges of highwalls
- dangerous atmospheres [e.g. oxygen deficient air, unsafe levels of poisonous gases such as methane (CH4 ), carbon monoxide (CO) and hydrogen sulfide (H2S)]
- radioactivity [e.g. naturally occurring radioactive decay product such as radon gas (Rn)]
- unstable explosives (e.g. ageing and deteriorating blasting caps)
- dangerous chemicals (e.g. cyanide, arsenic and mercury leaking from deteriorating containers)
- wildlife (e.g. snakes).
Contributory factors
- Inadequate barricading or signage to existing workings.
- Deterioration of safety signage.
- Unidentified or obscure existing workings (e.g. hard-to-see vertical shafts).
- Poor visibility (e.g. darkness inside mines, hidden hazards under water).
- Deliberate disregard of safety signage or barricading by members of the public.
- Use of social media to promote an unoccupied mine site for recreational purposes.