Gas Risers. “It was suggested that the gas risers be checked and the flows measured. The Mine explained that the gas risers had been turned off on the surface.”
Now we have the issue of Gas Risers in the area.
How many are there in and around 9Nth and where?
The Mine Insists they are all turned off.
There is no indication of when the Gas Risers were turned off
The Mine found 38 boreholes a month after saying Management stated the surface had been checked and all boreholes were capped and sealed.
Assurances one way or the other given about the status of gas risers being turned off aside, what about the proposition Inspector Marlborough puts forward.
If the methane drainage gas risers have been turned off and methane is free venting into the mine, what sort of quantities and where is it being vented?
Were the gas risers in 9Nth turned off in an effort to increase the methane in the goaf and bring the inert fringe closer to the Longwall face?
If so when?
What impact has the closing of the gas risers had on any potential interpretations from the gas data and ventilation models, especially combined with boreholes that have been uncapped?
5TH OCTOBER
During the night the Mine had located 38 surface to seam holes and identified 5/6 that were breathing in strongly. These have all been sealed.
The gas results from shaft H9 were discussed. It was acknowledged that there was still activity occurring underground, and this was probably a gas fire. There was discussion regarding the results from various locations and it was generally agreed that more detailed analysis was required to make any conclusions.
There was further discussion regarding the air quantity coming out of Shaft H9 and how this could be measured, or estimated. This would give valuable information to help understanding the status of the Mine, There was discussion around possible sources of additional Methane.
It was suggested that the gas risers be checked and the flows measured. The Mine explained that the gas risers had been turned off on the surface.
I recommended that the Mine reconsider this with a view to opening up the risers. The hazard being that, by closing the gas risers, the boreholes would pressurise from the underground methane standpipes. This pressurised gas could then cause the underground water traps to blow out. This would result in the in seam gas drainage holes free venting into the underground mine atmosphere. The Mine agreed to review this.
4th SEPT
Verified that all surface boreholes over the 9 North goaf were capped or sealed;
25th SEPT
Darren Brady recommended most effective location for majority of N2 to be applied is GN2470 e
Potentially 02 is still being supplied to Goaf, focus and inspection will be conducted on adjacent Goafs 8 and 7.
CO past TB 14 needs to be seen to be not replenishing before an assessment can be made heating is arrested.
Discussed the influence of high H2 on the Oxygen Nose Point in current samples and to ensure it is considered when assessing explosibility risk.
