11 The evidence in the proceedings revealed the following relevant facts:
(a) The Mine is situated on and mines what is known as the "Whybrow seam". The Whybrow seam contains claystone bands of various thicknesses. The then Wollemi mine (which became part of the Wambo mine) commenced operations in July 1997 extracting the Whybrow seam coal.
(b) The Whybrow seam generally and the mine particularly, have a history of injury caused by "rib failure". That is, material constituting the wall, or rib, of the mineshaft may come away from the rib and fall onto the floor of the Mine. The material separating from the rib is referred to as "rib spall".
(c) The method of mining used at the mine was the longwall method. Longwall mining is a system of mining coal in which the seam is extracted on a broad front or wide face. A typical longwall block could be 200 metres wide by 2000 metres long. The longwall shearer operates across the 200-metre face shearing approximately one metre at a time. The roof is maintained by a series of hydraulically operated shields/chocks which move forward as the longwall is extracted. The cavity is allowed to collapse as the longwall advances. In his affidavit Dr Galvin said of longwall mining:
Longwall mining constitutes the safest form of underground coal mining. It minimises the amount of first workings driveage, thereby significantly reducing the time that mineworkers are exposed to roof and ribs at the face.
(d) As at 6 March 2001 the Mine had 5 continuous mining machines. These included two single pass, remotely controlled machines fitted with hydraulic roof and rib bolters. These machines were CM9 and CM11. A single pass machine has a wide cutter head and enables the full width of the roadway to be mined in one operation. As these machines cut into the coalface and moved forward, the roof and walls of the mine are drilled and bolted using steel bolts (or, in some circumstances, fibreglass dowels for rib bolts) up to 2.4 metres long inserted at pre-determined intervals along the roof and walls. The effect of roof bolting is to secure the roof from caving in by clamping layers of sediment together to build a laminated beam. Similarly, rib bolting is designed to prevent parts of the wall breaking away.
(e) The remaining three machines were dual pass machines, that is, machines with narrower cutting heads. These machines were CM7, CM8 and CM12 and they were not fitted with hydraulic rib bolters. The machine against which Mr Davies was crushed was CM12.
(f) The crew on the evening shift (6.30pm - 2.00am) on Monday 5 March 2001 refused to work in the Longwall 13 Installation Roadway due to the presence of overhanging ribs on the right hand or block side.
(g) The night shift (12.45am - 8.15am) for Tuesday 6 March 2001 bolted the ribs in the Longwall 13 Installation Roadway as far as the rear of the continuous miner (approximately 13 metres from the face) using an Eimco (general purpose articulated vehicle) mounted hydraulic rib bolter. CM12 remained at the face while rib bolting was undertaken. The night shift also cut one metre from the face.
(h) The day shift (7.00am - 2.30pm) for Tuesday 6 March 2001 cut a further 8.5 metres in the Installation Roadway and installed no rib bolts.
(i) The afternoon shift (12.15pm - 7.45pm) for Tuesday 6 March 2001 was a three-man maintenance crew that carried out no development in the Installation Road nor did it undertake any rib bolting.
(j) On Tuesday 6 March 2001 the evening shift commenced at 6.30pm. A crew consisting of the nine men that are the subject of the charge was assigned to carry out production in the Longwall 13 Installation Roadway. The men, including Mr Davies, were very experienced miners. The panel deputy Mr Durie had 20 years' experience. Continuous miner operator Michael Ball attended the face of the Installation Road and cut a car of coal using CM12. He then "scaled" the right hand rib down with a rib bolt and the side of the head of the continuous miner. Scaling means to bar down or scrape off loose ribs or roof. Michael Ball and Robert Davies then installed four roof bolts at the face, and inspected and sounded the unsupported rib.
(k) Prior to work commencing on evening shift the miner driver, Michael Ball and the Deputy Mr Durie, both inspected the ribs closely. They paid particular attention to them as Mr Ball had been the person who had not wished to operate the continuous miner the previous evening having regard to the state of the ribs and Mr Durie had endorsed his assessment on that occasion. On 6 March 2001 they were each satisfied that the ribs appeared safe.
(l) At about 8.00pm Robert Davies took over the operation of the continuous miner and cut two further cars of coal from the face. The distance from the last rib bolts to the face was now approximately 23 metres.
(m) Members of the evening shift crew had occasion from time to time to position themselves between CM12 and the unsupported rib. This was to carry out tasks that included roof bolting, extending ventilation tubes, and carrying out inspections and maintenance.
(n) At approximately 8.15pm, whilst Robert Davies was standing on the right hand side roof bolting platform of CM12, a large piece of rib coal fell from the right hand side of the heading and crushed him against the side of the continuous miner, resulting in fatal injuries.
(o) The coal that fell from the right hand rib had been exposed by the cut on day shift 6 March 2001 and had been standing unsupported for between approximately 7 and 13 hours at the time that it fell.
(p) Utilising the CM12's hydraulic roof bolters, roof bolts were installed in the Installation Roadway as it was developed in accordance with the Mine Manager's minimum support requirements of the time. These provided that roof bolts were to be installed every 1.5 metres with a maximum of 6 metres of unsupported roof at the face. In practice the roof was bolted to approximately 3.4 metres from the face, coinciding with the position of the roof bolter on CM12.
(q) At the time of the accident CM9, the machine fitted with hydraulic roof bolters, was situated approximately 145 metres from where the accident occurred.
(r) Section 102 of the Coal Mines Regulation Act 1982 states that the Mine Manager shall make Support Rules that are not inconsistent with the Act, with respect to the support of roof and the sides of working places and roadways in the mine. These Rules are subject to the approval of a District Inspector of Mines. The Support Rules in place at the time of the accident required rib support/bolts to be installed where necessary at maximum spacings of 2.0 metres.
(s) The Mine Manager's minimum support requirements at the time of the accident provided "All exposed ribs… to be supported … within 24 hours of excavation." The 24-hour rule came into effect after a Mines Inspector advised the Mine manager in July 1998 that "no rib up to the continuous miner shall remain for more than 24 hours in an unsupported state". This requirement was adopted at the Mine and applied at the time of the accident in March 2001. The 24-hour rule was part of a number of control measures proposed by the Department of Mineral Resources and developed over time following injuries to a colliery fitter in February 1995 from rib spall. The measures were designed to prevent rib spall being caused by a thick claystone band in the coal seam expanding when exposed to atmosphere and moisture, thereby creating tensile forces in the adjacent coal and causing it to split.
(t) Support in relation to the right (or block) side consisted of 1.2 metre fibreglass dowels and wooden blocks at 1.2 metre maximum intervals. The bolts were installed in a 'W' pattern with one bolt installed 600mm above the bottom of the clay band and the next bolt installed 600mm below the roof.
(u) In accordance with management directions, rib bolting was effected once in each 24 hour mining cycle using an Eimco mounted hydraulic rib bolter to install rib bolts up to the rear of the continuous miner (i.e. approximately 13 metres from the face). Accordingly, rib bolts were last installed prior to the accident in Longwall 13 Installation Road on the night shift of 6 March 2001 when the ribs were bolted up to the rear of CM12.
(v) The level of supervision at the mine at the time of the accident was adequate and in compliance with that required under the Coal Mines Regulation Act 1982 and the Mine Inspection Plan. The defendant's regard for a proper and effective system to protect the health and safety of persons in the Mine was not in issue.
(w) The underground Wollemi mine is currently on "care and maintenance". This means that the mine is ventilated and kept open for inspection as it may be used in the future to access one of the lower seams.
(x) The defendant cooperated with the Department of Mineral Resources in its investigation of the accident.
(y) The defendant provided assistance to employees and Mr Davies' family by way of counselling following the accident. The defendant deeply regrets Mr Davies' death and the impact on his family.
(z) In relation to what occurred on 6 March 2001 Dr Galvin said in his report:
In my experience, I have not encountered such a large slab of coal falling from the rib as one body in first workings driveage. Had the single pass remotely controlled continuous miner fitted with roof and rib bolters been employed at the time, I am unsure if the incident would have been avoided. This is because the rib bolters were on the outbye side of the operator's onboard platform. Therefore, a significant portion of the slab, including that immediately adjacent to Mr Davies, would still not have been supported. The potential may still have existed for a portion of this slab to fall and to result in the same consequences.
(aa) In his affidavit Mr Sutherland opined:
I still regard the fall of coal which struck Mr Davies as atypical. In my search of company records I did not find any prediction of a fall of this kind or suggestion that ribs required immediate bolting for reasons of safety. Otherwise the Support Rules would have required this. As I pointed out above, the Support Rules had been developed with the active involvement and under the direction of a number of Inspectors. It was their recommendations and directions that appear to have given rise to the 24 hour rule.
(ab) In his conclusions, Senior Inspector Carey stated:
7.1 Rib spall (failure) had been identified as a hazard at the mine prior to the accident. The system of mining in place failed to adequately address the risk that hazard posed as it failed to manage the probability of exposure or the magnitude of the consequences of an exposure to the hazard. Allowing ribs to remain unsupported for up to 24 hours placed no limit on the possible advance between rib support installations. This approach along with then only bolting ribs to the back of the continuous miner meant that some tasks within the mining system must be conducted adjacent to unsupported ribs and at times between unsupported rib and continuous miner.