At approximately 9.15 pm on Tuesday 25th March 1997 Mr Trevor Domrow, section deputy, received serious injuries from the toppling of a large lump of coal (3.5 metres long, 0.5 metres thick and 1.0 metres high) from the south east unsupported rib adjacent to survey station 149 in the No.1 south west panel. (refer plan No. G13 - exhibit 2.)
At the time of the accident Mr Domrow was carrying out repairs to the left hand side roof bolter of the continuous miner.
He subsequently died as a result of these injuries at Ipswich hospital at 11-04 pm on that date.
Prior to the accident and in accordance with the normal mining sequence, a left hand break-off had been formed off the conveyor belt roadway. The face had been advanced about ten (10) metres from the intersection. Mining operations had continued without incident and no unusual conditions were evident.
The production crew had just completed scaling down the left hand rib adjacent to the accident site using the head of the continuous miner, a remote controlled, Joy 12 CM 12. Loose coal was loaded onto a shuttle car and the continuous miner was trammed back from the face and positioned for the installation of roof bolts.
Before these roof bolting operations were to commence, Mr Domrow noticed that a hydraulic fitting on the left-hand, machine mounted bolting rig had been damaged. This fitting was leaking hydraulic oil which effectively disabled the bolting rig.
Mr Domrow instructed the miner operator, Mr Rew, to withdraw the continuous miner outbye and away from the rib which was cracked and appeared unstable. The miner was moved about 2 to 3 metres and after an inspection of the rib, Mr Domrow instructed that the machine be withdrawn further. The continuous miner was moved another 2 to 3 metres. This area was examined by Mr Domrow and the shuttle car driver, Mr Knack, and these men concluded that the rib was stable and therefore safe to commence repairs to the bolting rig.
Shortly after, these two men were joined by the continuous miner operator, Mr Rew, and repairs to the machine were commenced.
Mr Domrow was bending around the unit when the Under Manager, Mr Bitmead, observed movement in the upper portion of the rib. He immediately shouted a warning, however, a large portion of the upper rib toppled over striking Mr Domrow and, to a lesser degree, Mr Rew and Mr Knack.
Mr Domrow, who was seriously injured, was removed very quickly by those present who should be commended for their valiant efforts in removing him from further danger and transporting him to the surface without undue delay.
We are of the opinion that the method of strata support offered little protection from rib spall. No effective rib support was required by the Managers Support Rules, nor any installed as a matter of choice by the persons working at this particular place.
Recommendations
The Queensland Department of Mines and Energy require mine operators to prepare safety plans for "Strata Management". These plans must address the support systems required for both roof and sides of mining excavations. The support systems must take account of premining stresses and mining induced stresses. In essence the support systems should be designed to maintain the physical integrity of both roof and rib elements so that they can safely withstand the sum total of the pre-mining and mining induced stresses. The following
factors need to be considered in the development of "Strata Management Plans":-
- The systematic support of the roof and ribs;
- A sequence plan showing positions, intervals and types of support;
- Wherever maintenance work is to be carried out underground on equipment, a procedure must be in place to ensure that the roof and sides are adequately supported;
- The relationship between seam dip and excavated section on rib failure hazards.
The development of strata management plans requires risk assessment using geotechnical information.
Mine operators should establish and maintain a systematic audit process, to ensure that the plans and procedures have been properly implemented and reviewed.
All personnel must receive competency based training to implement the requirements of the strata management plans.