Análisis integral de rentabilidad

The mine surveyor’s role in risk mitigation, is to accurately measure, map, monitor and report on factors which are potential causes of major safety incidents which could result in harm to people, damage (to property, infrastructure, or the environment), breach of law and loss. This includes, but is not limited to; showing all known physical hazards (including geological structure) on mine plans; geospatially guiding/directing mining through or past hazards (including possible concentrations of water and gas); stopping mining at prescribed limits or

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boundaries; preparing plans showing the full extent of current, old and adjacent workings; preparing mine ventilation and rescue plans; and ensuring effective communication of geospatial information which has a bearing on mine health and safety.

A mine disaster is generally defined as an accident or incident in which there have been multiple fatalities. There are four principal causes of mine disasters, namely, fires, explosions, inundation (ingress of water) and falls of ground.

The following examples of major accidents and incidents have direct geospatial relevance.

2.7.1

Gretley Colliery – New South Wales, Australia (1996)

Nature of the incident: multiple fatality caused by inrush of water from adjacent abandoned mine workings.

The report of a formal investigation under Section 98 of the Coal Mines Regulation Act 1982 by his Honour Acting Judge J.H. Staunton (1998), provides a description of the accident:

“At about 5.30 am on 14 November 1996…Four men of a team of eight were in the process of developing a roadway…, operating a continuous mining machine. The remaining four members of the team were in a crib room a little distance away. “Suddenly, with tremendous force, water rushed into the heading from a hole in the face made by the continuous miner…The four men were engulfed by the water, swept away and drowned…

“The water came from the long-abandoned old workings of the Young Wallsend Colliery. The mine was working to a plan, which had been approved by the Department of Mineral Resources. The plan showed the Young Wallsend Colliery more than 100m away from the point of holing-in. It is now clear that the plan was wrong. At the commencement of the night shift at 11.00pm on 13 November 1996, the Young Wallsend Colliery was only 7 or 8 metres away”.

2.7.2

Quecreek underground coal mine – Pennsylvania, USA: 2002

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According to the overview of the report of investigation into the Quecreek #1 mine by the United States, the Department of Labor Mine Safety and Health Administration (2003), “On Wednesday, July 24, 2002, at approximately 8:45 p.m., a nonfatal entrapment accident caused by a water inundation occurred at Quecreek #1 mine,…Water broke through the working face of No. 6 entry on 1-Left section from the abandoned Harrison No. 2 mine…The 1-Left crew attempted to escape but was blocked by water at the mouth of 1-Left panel. The 1-Left miners were trapped from 76 to 78 hours. Seven miners from 2-Left section and two outby miners were able to escape.”

“The primary cause of the water inundation was the use of an undated and uncertified mine map of the Harrison No. 2 mine that did not show the complete and final mine workings...The root cause of the accident was the unavailability of a certified final mine map for Harrison No. 2 mine in the State of Pennsylvania’s mine map repository.”

2.7.3

San José mine – Atacama Region, Chile (2010)

Nature of incident: non-fatal entrapment caused by fall of ground (collapse). Livingstone-Blevins (2010) commented on the San José mine incident in an article titled “Getting it right saves lives and mitigates risk”. In the absence of an official report as reference, the following summary has been extracted from the article. “To summarise the events, on the 5th _{of August [2010] an area of unstable ground}

caused the collapse of the main access decline of the San José mine. 33 miners were trapped some 700 metres underground…The extent of the collapse, some 400 to 500 metres below surface, was so large and the instability of the collapse area so great that there was no chance of excavating the hundreds of metres through broken rock to reach the depths of the mine. A decision was made to drill from surface into a chamber adjacent to a refuge bay located 670 metres below surface – if they [there] were any survivors they should have made their way to the refuge bay. Several methods of survey were used to check mine plans (maps) and down-hole survey instruments were used measure drill-hole direction and inclination...After 17 days of drilling, a 14cm diameter hole 701 metres in length holed into the chamber. When the drill was withdrawn, a note had been attached to the drill bit that read that all 33 missing miners were alive! This hole became the

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conduit for communication and sustenance for the miners…Three simultaneous boreholes were commenced (Plan A, B and C), targeting different routes through the rock and different terminal points in the mine…Special equipment was designed and fabricated which included special large diameter drill-bits (710mm) needed to create holes large enough to accommodate the escape capsule. Plan B reached its target first on the 11th _{of October, after commencing drilling on the}

5th _{of September. On the 12}th _{of October hoisting of the miners to surface}

commenced. All miners were rescued”.

2.7.4

Gleision Mine incident – South Wales, United Kingdom (2011)

Nature of incident: multiple fatality caused by inrush of water from old mine workings.

The report of a formal investigation by the Health and Safety Executive (2015), the following summary provides a description of the accident: “On the morning of 15 September 2011…around 9.30 am, the first round of explosives was fired…The blast released a large body of water from old workings which rushed into the working stall, which was the part of the mine from where coal was being extracted…Such was the volume and speed of the water inrush that four…men …died. [A fifth man] was injured but managed to escape through the old workings and emerged on the surface about an hour later. [Two other men who were] further away from the stall, just managed to escape to the surface and raise the alarm”. “During the investigation, the mine was re-surveyed to assess the accuracy of the plans used at the time of the accident. The report states: “An outcome of the resurvey was that the edge of the bottom-most of the Old Central Workings was about 7 m further to the south-east than shown on the mine plan; in other words 7 m closer to where the miners were tunnelling. This would not be wholly unexpected given what is known about potential inaccuracies in mine plans as described in ‘Mine plans and the mine survey’ of this report”.

The report includes a significant body of detail related to mine plans, survey practice and risk management. It also states that “…the circumstances leading up to the incident were considered and taken into account during the development of the Mines Regulations 2014 which are now in force”.

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• Three of four of the incidents described above (Gretley, Quecreek and Gleision) can be directly linked to deficient geospatial records which resulted in inrush of water.

• Two of the incidents (Gretley and Gleision) resulted in multiple fatalities. Lessons from both incidents were addressed in subsequent revisions of regulations.

• Two of the incidents (Quecreek and San José) demonstrate the role of accurate geospatial information and surveying in the successful rescue of all trapped miners.

• Two of the incidents (Quecreek and San José) resulted in mine closure, demonstrating socio-economic consequences (formal inquiries and investigations have a health and safety focus and typically do not consider other consequences).

• Two of the incidents (Quecreek and San José) in which the trapped miners were rescued were made into films.

• In all four incidents, personal and company/employer reputational damage was significant (in some cases coupled with civil lawsuits and prosecution).