High Levels of Ethylene Moranbah North Spontaneous Combustion Feb 2021. RSHQ Inspector MRE 24th February 2021

Inspector Brown attends Moranbah North on the 24th February 2021

1. 20210224 MRE

Ethylene gest mentioned a few times.

Obviously there was lots of Ethylene detected. I wonder how many parts per million (ppm) of Ethylene are considered high

• Gas sensors at goaf wells that were exposed to high levels of Ethylene and Carbon Monoxide have been changed out and quarantined.

Inspector Brown talks about the gas trends on site and who has been engaged as Independent Technical Experts

• I asked Mr to follow up on the gas Trend pages provided to me by the site 22/02/21 , another mines name has appeared on the top left corner of the page however the trends were identified as MG605. It appeared to be an anomaly within Seagas however needs to be verified.
• I asked for an update of who has been engaged by Moranbah North Mine as Independent technical experts. This was provided verbally by the SSE and recorded in my official notebook.

I will be asking for the gas trends provided on the 22nd of February as well as the existing LW Active Goaf Spon Com TARPS as part of the next RTI application

 

At the conclusion of the MRE Inspector Brown makes the following statement

• I provided an overview of what an Inspectorate Investigation would involve, at this stage it is my immediate focus to deal with the situation at hand which has the mine under Directive to not re-enter the mine. The level and type of Investigation will depend on critical evidence required for the Directive response.

I will be asking for the final RSHQ Inspectorate Investigation as part of my next RTI as well as drafts

I will also be asking for the Investigation Report that Anglo must provide the RSHQ. Anglo refer to these as LFI’s

 

Points I have noted as they appear in the MRE are

There are video’s of the event taken by multiple cameras across the whole longwall face. Inspector Brown was provided what MNC considered the most relevant position on the 22nd. (This video will be part of my next RTI)

• Documents and video footage provided to Inspector Brown Monday 22/02/21 were covered in some discussions.
• Additional videos are now available across the face since the first section of footage was provided. (the videos were later viewed but not requested to be provided to the Inspectorate at this stage)

Inspector Brown then lists all the current number and type of Inertisation Units currently operational (5) and at least another 3 being brought into operations in the near futures

The site is preparing for an increase in Inertisation capability. Mr XXXX explained the site currently have 2 x OSGS Units, 1 x Floxal and 2 Tomlinson Boilers. Site were in the process of sourcing a 3rd Boiler, an extra Floxal unit (on route from Brisbane) and there were 2 x Nitrogen units being unloaded on site today. Further to this there were 3 trailer loads of foam delivered to site.

Inspector Brown then sets out the planned 5 extra inertisation boreholes being drilled into the areas where it had been determined was the most likely area for a spontaneous combustion heating in what are obviously Tailgate side gas drainage goaf wells 869-865

The location of these 5 new inertisation was decided by the technical experts (both internal and external to Anglo)

• There are two drill rigs mobilising to commence a 5 hole drill pattern. Mr provided a plan to the meeting of the proposed drilling location bias MG side of goaf wells 869-865 but still in close proximity to the TG chain pillars. It was explained the site had engaged independent parties to assist their own technical experts in determining where any potential sources of heating could have occurred and the most effective locations for surface to goaf drilling for further Inertisation.
• I asked the question about the extent of data researched for validation of the proposed 5 new Inertisation holes into the goaf. Responses provided were that of an extensive amount of data has been considered in making these assessments. It is acknowledged the plan is also still a work in progress, when the plan is closer to being finalised I will give consideration to requesting a copy under Notice.

There has obviously been a number of Spontaneous Combustion TARPS triggered in LW 605 prior to 1845hrs 20/02/21.

Again Ethylene is mentioned and it is likely that it was involving goaf wells 869-865 

• We discussed the recent history of spon com triggers reached in LW 605, the location of these areas are in close proximity to the goaf wells where Ethylene and Carbon Monoxide presented to after 1845hrs 20/02/21.

Lastly there are a number of issues discussed with the use and application of gas ratios used

• I raised for discussion and verification that persons on site were considering the following:
• Graham’s Ratio recorded and possible influence of Nitrogen from Inertisation.
• Trickets Ratio, was it considered and if so was Nitrogen adjusted to recognise Inertisation that was already in place.

• Was CO/C02 ratio considered.

MR XXXXX confirmed these ratios had been taken into account and formed part of their assessment of the mines environment. Mr XXXX provided updates of the underground environmental monitoring which identified the mines current status as being stable and reflecting normal background levels of gases and ratios.

• Currently the mine is operating 4 blow skids, in normal operation and normal rate of retreat it was explained this would look more like 7 goaf wells operating, 3 deep in the back of the goaf.
• I asked if the site had engaged with QMRS in any capacity at this point in time, the SSE confirmed contact about resources (if required) had been conducted.
• I raised for discussion if a Radon Survey had been considered. I further advised this is a question for their team of experts to determine if it would provide value.

• I provided advice on the matter of site security to the SSE with the view the current status could continue for a period of time. Site Security and restricting access is a matter for the SSE to determine.