North Goonyella Mine Fire 7th October 2018. “Shaft H9 . Further discussion revealed that the tube bundle sample point here is not actually in the shaft itself, but in a length of ducting in some of the refrigeration infrastructure.”

MRE – North Goonyella – 07.10.2018.pdf

 

Today, 7 Oct 2018 I, Inspector Les Marlborough, attended a meeting at North Goonyella Mine to discuss the status of the spontaneous combustion event at North Goonyella Mine and the subsequent mine evacuation. The meeting was held at the North Goonyella accommodation village in the IMT Room.

Meeting

Attending the meeting was;

Mr John Anger, SSE;

Mr Marek Romanski, UMM;

Mr Chris Markowski, Tech Services Superintendent;

Mr Gareth Prichard, Planner;

Mr Zac swift, SSHR.

In addition, the meeting was joined by video/telephone conference by;

Mr Stephen Wood. ISHR;

Mr Nev Impson, Compliance Manager;

Mr Dennis Black, VO;Dar

Mr Mike Carter, SSE Millennium Mine;

Mr Shaun Dobson, DCICM;

Mr David Cliff;

Mr Darren Brady,

Mr Martin Watkinson (SIMTARS).

Meeting

Last 24 Hours;-

0 Gag not running from 06:45 to 22:15. This due to issues found during planned maintenance

Entry with the afterburner requiring repairs to an afterburner cone which had to be repaired in Moranbah. Then, on start-up there was an issue with the water boost pump and, an issue with fuel (flat battery on fuel pump). The GAG was run undocked to calibrate the unit and then had to be manually docked due to a failure of the hydraulic pump.

Borehole GN2702 (MG A Hdg 1-2 CT) Set up CS gas rig and Wilson Rocsil pumping system. Started pumping in the afternoon and completed seal in 9N Conveyor Road 1-2 CT at 22:15. 250m pumped.

• Borehole GN2701 (MG Chute Road) — Milled out hole, Hole tight from 300m, rods tripped out at 1 AM. Rig off hole at 3:00 AM and set up QMRS foaming unit on hole ready for DS drilling into workings,
• GN2704 (TG Roadway) — Set up over hole and commenced drilling, Down to 60m end of NS,
• Floxal Unit #6 set up over 42 CT (Stone Dust Silo). This running S PM and all night. No information on measured quantity being injected.

Floxal Unit #2 at 6 CT in the Corridor. Run all night. No report of quantity being Injected.

I stressed the importance of measuring what was being injected.

• Atmospheric monitoring and temperature measurement to be set up on Borehole 2701 today prior to Rocksil injection;
• Borehole monitoring at various locations conducted;-

1. H9 Shaft 4 hourly;
2. GN2700, GN2695, GN2698 6 hourly;
   3. Set up at 27 CT 9 N (first reading showed fresh air, resampling);
   4. Setup at 36 D-E and 44 CTEhdg.

• Fresh Air found at MG9N 27 CT and 44 CT E Hdg. Confirming samples. (Soot reported at 27 CT 9N hole collar on the surface). 36 CT D-E sample to be confimed. 27 CT MG 9N reported to be high methane in hole.

Emergency sealing prep works continued.

Next 24 Hours

Continue GAG operations;

GN2701 Rocksil Plug works;

• Continue drilling for LW containment;
• Validate heat temperature reading at 119 Shaft;
• Continue Sampling Regime;
• Revise Floxal Strategy;
• Preparation of sealing strategy;
• Conducting prep work for Radon heat survey.

Gas Results

Discussion was held regarding the gas results overnight.

Very quickly, after the GAG was turned off, the gas at the Bleeder Shaft looked similar to that which was seem at H9 Shaft when the GAG was running.

Mr Cliff stated that this suggests that the GAG gas is not going over the heating source. He also stated that there was no evidence of GAG gas detected in any of the samples taken from the 9N goaf area.

There was discussion regarding a sample at H9 Shaft at 18:25 on 6 Oct. It was suggested that this was a sampling error as it showed high Oxygen (19.71%) and low CO (79 ppm) and methane (1.3%). The sample was almost fresh air.

However, the following sample, taken at 21 :50, also showed higher than normal oxygen and lower than expected other gases as the previous sample, but not as dramatic.

Mr Cliff and myself believed that this was an indication of the ventilation reversing in Shaft H9 when the GAG is not running. Further discussion revealed that the tube bundle sample point here is not actually in the shaft itself, but in a length Of ducting in some of the refrigeration infrastructure.

I questioned why a re-sample was not taken during the night instead of waiting to the following day before investigating. I recommended that the Mine should ensure that, whenever a suspect or very unusual gas result is identified, it should be automatic that a re-sample is taken to verify the reading. I also recommended that the Mine consider putting the gas results out in an excel spreadsheet with Tabs for each sample point rather than simply sending the Ezgas print out sheets. This enables the people receiving the results to easily look at how results are trending and how they compare to previous samples. It would also reduce the number of e-mails being sent out.

Inspector Dobson asked what the longer term plan was. Mr Anger responded that the plan was to pump concrete into the Chute Roads etc. around the Longwall to insert a concrete plug. These would probably be put in between a second Rocksil Plug to be inserted into each road. The Rocksil to act as formwork for the concrete plugs. It was estimated that this process would take a minimum of 14 days to complete this work.

After completion of the meeting I had a discussion with Mr Romanski and Mr Anger regarding their use of self-rescuers on the surface, The use of the self-rescuers was determined as a control by the Mine when there was large quantities of smoke issuing from the Mine. This is not now the case. The Mine intends to review this requirement and review the risk assessment to determine what is now required given the current circumstances. I suggested a risk based approach to determine what is required to achieve an acceptable level of risk.

We also discussed the longer term strategy. Following the sealing of the Longwall, the Mine intends to monitor the Mine atmosphere, both inside the sealed area and around the mine workings with a view to determining the level of risk to be able to review the No Go Zones that the Mine currently has in place.

I advised that the Mine needs to ensure that they have established sufficient reliable monitoring points around the Mine and in the sealed area to be able to effectively analyse the situation and that the Mine needs to determine from the monitoring results that the risk of explosion has been reduced to an acceptable level. The Mine can then use a risk management process to determine the controls required, which would include the need for and size of, any exclusion zones that may or may not be required.

I advised the Mine that Inspector Richard Gouldstone would attend the Mine on Monday 8 Oct 2018 at 08:00 AM.