Mines Inspectors Report after 5 Methane HPI’s in 2 Days 18th January 2018

MRE – Grosvenor Coal Mine – 18.01.2018.pdf

Between the 6th and 8th of January there were Five (5) methane HPI’s in the Tailgate of LW 102.

The first when the Longwall had retreated 29m and the last when at the 40m mark.

The only issue raised by the Inspectors at the Close Out meeting were content of ERZC Statutory Reports

3.0 Close-out Meeting

Inspector Marlborough raised the issue of ERZ Controllers not including on their statutory reports information regarding gas alarms reported to them by the Control Room Operator. It is important the ERZ Controllers not only record these reports, but they should also write on  their reports the results of their investigation into the alarm and any actions taken as a result. Inspector Marlborough suggested that the mine communicate this to their ERZ Controllers.

Shearer positions vary from Chock #66 to #149.

Difference between 400m Inbye Sensor and Outbe Sensor varies between 0.22% on the 6th January to 0.47% on the 8th of January. The last 4 HPI’s have an avergae of 0.47%.

Therefore the methane make from the tailgate between the the 400m metre Inbye Sensor and the Tailgate Dogleg Sensor can easily be calculated by multiplying the ventilation quantity by the percentage.

If there was 80 cubic metres of ventilation the methane make between the 2 Sensors is

80 x 0.005 = 0.4 cubic metres per second.

Inspectors Marlborough and Gouldstone note discussions about Grosvenor Management about initial caving of goaf and “difficulties” of goaf holes being drilled due to proximity to Isaac River and river sands.

A methane HPI in Development on the 17th of January due to a “plug of methane” was generated at a methane drainage stub.

Inspector Marlborough made reference to other experiences in the Bowen Basin at mines where exceedances had occurred. Following exerted pressure from the Department and greater recognition by Mines of the hazard of elevated methane levels, substantially more effort and investment had been made into methane drainage capacity and efficiency. This was clearly increasing the amount of gas drained, decreasing operational downtime by early intervention to avoid exceedances rather than cutting to trigger trip events. Most importantly risk was being reduced.Inspector Marlborough references exerted pressure from Department and greater recognition of dangers of elevated methane resulting in substantial effort and investment into methane drainage, increasing methane drained, lowering downtime and avoiding Methane Exceddances rather than cutting to trigger methane trips events. (HPI’s). Most importantly risk was being reduced.

Whatever pressure that was “exerted” by the Mines Inspectorate does not seem to be acting at Grosvenor

The stress notch mentioned in the Underground Longwall Inspection is when LW 102 Mines Past the Installation Road of LW 101.

Fire extinguishers on longwall face are hard to locate and inconsistently spaced.

2.1 Surface Issues

On examination of ERZ Controllers reports there are safety related items reported in production reports which have not been recorded on the statutory reports.

Inspector Marlborough on examining and questioning the Gas Alarm Log and CRO identified that ERZ Controllers, on receiving alarm notification are not recoding the detail and action taken in their statutory reports.