Grosvenor Inquiry Submission KEY ISSUE 2 ADEQUACY of the MINE’S RESPONSE to HPI’s on LW 103 and 104 between 1st JULY 2019 and 5th MAY 2020
THE LINK ABOVE has the SUBMISSION with Coloured highlights
ANGLO MANAGEMENT Responded inadequately to the HPI’s.
ANGLO MANAGEMENT HAVE RESPONDED INADEQUATELY SINCE FEBRUARY 2016 when they were AWARE.
a) “that in future there will be “MORE CHALLENGING CONDITIONS for EFFECTIVE PRE-DRAINAGE of METHANE from GOONYELLA MIDDLE SEAM and SURROUNDING STRATA.
b) METHANE HPI’S > 2.5% CONTINUE IN DEVELOPMENT from FEBRUARY 2016 FROM FLOOR STRATA METHANE INRUSHES up TO DEVELOPMENT MG LW 104 and
c) METHANE HPI’S > 2.5% in LW OPERATIONS from INADEQUATELY DRAINED ROOF STRATA starting in LW 101 and becoming MORE FREQUENT with EACH subsequent BLOCK
FINDINGS
- DNRME (RSHQ) MINES INSPECTORS and GROSVENOR MANAGEMENT both aware and have documented on FEBRUARY 11th 2016, that in future there will be “MORE CHALLENGING CONDITIONS for EFFECTIVE PRE-DRAINAGE of METHANE from GOONYELLA MIDDLE SEAM and SURROUNDING STRATA.
MRE VENTILATION AUDIT 11th FEB 2016 (attachment 1)
ANGLO NOT ADEQUATELY INVESTIGATING FLOOR METHANE INRUSH HPI’s or REPORTING THEM to RSHQ INSPECTORS MARCH to MAY 2017 RESULTING IN RSHQ INSPECTOR DIRECTIVE to CONTROLLING RISK of UNCONTROLLED METHANE RELEASES INDUCED BY FLOOR HEAVE
1 . Conducting investigations into the floor heave events causing uncontrolled releases of methane contained within MREs dated 3/05/17, 4/05/17. (to be completed by 19/05/17) and:
- 2. Identify SHMS controls to be developed or reviewed specifically for identifying, managing and controlling the risk of uncontrolled methane releases induced by floor heave. Provide the Inspector with a report of actions taken immediately and proposed actions to address the issue. (to be completed by 26/05/17
3) ANGLO MANAGEMENT and RSHQ INSPECTORS AWARE MEGABOLTS MAY INTERESECT STRATA WITH SUFFICIENT METHANE TO BE AUDIBLE AND MAKE IT DIFFICULT TO PRESSURE GROUT BOLTS
4) ANGLO MANAGEMENT AWARE FLOOR EMISSIONS IN LONGWALL OPERATIONS CAN DRAIN SEAMS UP TO 40 BELOW the GM SEAM
5) ANGLO MANAGEMENT in Feb 2019 EMPLOY TWO AUXILLARY FANS TO VENTILATE MG LW104 DEVELOPMENT PANELS IN UNSUCCESSFUL ATTEMPTS to KEEP METHANE <2.5 after REPEATEDLY FAILING TO DO SO WITH ONE AUXILLARY FAN
6)GROSVENOR LFI RECOMMENDS to UNDERTAKE ADDITIONAL PRE-DRAINAGE for BOTH FLOOR AND ROOF STRATA which WILL REDUCE SPONTANEOUS COMBUSTION RISK by
REDUCING RELYING ON POST DRAINAGE HOLES
REDUCE RELYING on HIGH VENTILATION QUANTITIES on LONGWALL BLOCK and FACE
REDUCING DIFFERENTIAL PRESSURE
LFI IN.00226742 & IN.00228255
It is recommended to further identify the pre-drainage opportunities (both underlying and overlying methane bearing coal seams) through detailed gas reservoir analysis to reduce reliance on ventilation quantities and post goaf drainage measures. This in turn will reduce differential pressures across the face and goaf, and in turn spontaneous combustion risk.
EVIDENCE
- ANGLO NOT ADEQUATELY INVESTIGATING FLOOR METHANE INRUSH HPI’s or REPORTING THEM to RSHQ INSPECTORS MARCH to MAY 2017 RESULTING IN RSHQ INSPECTOR DIRECTIVE to CONTROLLING RISK of UNCONTROLLED METHANE RELEASES INDUCED BY FLOOR HEAVE
4th MAY 2017 MRE
The MG 103 floor heave events were discussed in detail.
I highlighted the incident report dated 1/05/17, this incident report identified “Off Scale” alarms on the 4 gas Altair instrument. The report also identified 1.35% methane present within the fan ducting.
The incident report does not contain the level of detail required to fully understand all circumstances and actions taken. The fact the Altair is recorded as off scale should escalate the investigation process and determine if CMW’s where exposed to danger being, methane greater than 2.5% in general body.
The incident dated 2/05/17 does not identify the level of gas that tripped the auxiliary fan which was stated by UMM Ivers to be 2.01% methane, again more detail and further investigation required.
There are numerous reports of floor heave through Statutory reports from 3/05/17 and back to 6/03/17 (which was as far back as I checked while on site).
There was a report on the 6/03/17 (report number 12984) of an auxiliary fan trip due to surge of methane.
Another report on 9/04/17 (report number 14091) of an auxiliary fan trip due to surge of methane after floor heave event.
My concerns from these events is there is a lack of follow up investigation into the circumstances. The current phenomenon of floor heave in the gateroads is not fully understood meaning understanding and tracking the mechanism that is initiating the heave and, where is the reservoir of methane that is being released during the floor heave events?
The hazard is not currently identified on the Geological Hazard Plans and is not referenced within the Permit to Mine.
A Directive was issued to the SSE in relation to the risk presented by the floor heave events.
Floor Heave and uncontrolled Methane release To reduce risk by:
1 . Conducting investigations into the floor heave events causing uncontrolled releases of methane contained within MREs dated 3/05/17, 4/05/17. (to be completed by 19/05/17) and:
- Identify SHMS controls to be developed or reviewed specifically for identifying, managing and controlling the risk of uncontrolled methane releases induced by floor heave. Provide the Inspector with a report of actions taken immediately and proposed actions to address the issue. (to be completed by 26/05/17)
- ANGLO MANAGEMENT and RSHQ INSPECTORS AWARE MEGABOLTS MAY INTERESECT STRATA WITH SUFFICIENT METHANE TO BE AUDIBLE AND MAKE IT DIFFICULT TO PRESSURE GROUT BOLTS
MRE 3rd MAY 2017
Gas leaking from bolt holes on MG 102 install face has been planned to pressure grout on the faceline, noted in the oncoming Nightshift planning notes.
We then walked up to the 102 install face which has already been widened recently. The standards along the faceline were clean & tidy, a stopping had just been completed at the MG end of the faceline and a ventilation was still to be constructed from the inbye chute back to the stopping, by the end of our inspection this was in progress.
We met ERZ Control Mr Gligor Turcus, Mr Turcus had just completed reading the faceline 1st and 2nd pass tell-tales. Mr Turcus was able to explain the actions required for the triggers represented on the faceline.
At approximately 230m chainage in the 2nd pass, leaking gas was heard from a Mega bolt. Mr Bryan investigated with his Altair and confirmed the hole was breathing out however the methane was quickly diluting into the G/body. Intake side of the hole methane was 0.3%-0.4%, within 1 meter of the hole return side the methane was 0.5%. A similar methane leak was found in the bleeder road (around 213m) at a roof bolt, in this location there had been prior attempts to pressure grout. The volumes produced while ventilation maintained was minor, the potential impact of this during an extended fan outage could be problematic for the 101 longwall the way the ventilation is established. UMM Ivers was following up on the matter.
- ANGLO MANAGEMENT AWARE FLOOR EMISSIONS IN LONGWALL OPERATIONS CAN DRAIN SEAMS UP TO 40 BELOW the GM SEAM
17th November 2019. GROSVENOR UNDERGROUND MINE MANAGER (WOUTER NIEHAUS), SITE SENIOR EXECUTIVE (ROB NOWELL at time of Report), TECHNICAL SERVICES MANAGER (LOGAN MOHR), ANGLO HEAD OF OPERATIONS (GLENN BRITTON) WERE AWARE THAT
That seams up to 40m below the seam floor should be considered for potential to emit gas into the LW working area/goaf. In the zone for this LFI, this would include the GML and the Harrow Creek Lower Measures
Reference GROSVENOR LFI IN.00211941 CH4 Exceedance LW103 Incident Date: 7 November 2019
https://coalminesinquiry.qld.gov.au/wp-content/uploads/2021/04/16.-LFI-investigation-report-for-HPI-07112019.pdf
NO ACTION TAKEN TO REQUIRE GROSVENOR MANAGEMENT TO TAKE ACTION TO PRE-DRAIN THE FLOOR SEAMS PRIOR TO LONGWALL MINING COMMENCING
Grosvenor LFI Reports acknowledge no concerns were raised with the Second Workings SOP.
No pre drainage of the GML seam has been conducted for LW104. The GML is expected to release gas due to the reservoir size combined with proximity to the working seam between Ch4000 and Ch2000 (MG104 20-36c/t)
LW 104 Second Workings SOP
https://coalminesinquiry.qld.gov.au/wp-content/uploads/2021/04/5.-SOP-LW104-Second-Workings.pdf
a) 06/03/2020 11:56
Notice of Intent to commence Second Workings in LW104 acknowledged via email from Paul Brown (Inspector of Mines).
https://coalminesinquiry.qld.gov.au/wp-content/uploads/2021/04/LFI-investigation-report-for-serious-accident-06052020.pdf
ANGLO MANAGEMENT EMPLOY TWO AUXILLARY FANS TO VENTILATE DEVELOPMENT PANELS IN UNSUCCESSFUL ATTEMPTS to KEEP METHANE <2.5 after REPEATEDLY FAILING TO DO SO WITH ONE AUXILLARY FAN
HPI 17th FEBRUARY 2019
An incident occurred in MG104 Development Panel on the 17th of February at 12:45pm.
The Continuous Miner was producing in C Hdg 27-28ct with the face at 188m from the last open ct. A floor heave event occurred releasing CH4 gas into working face in MG104. The Gas release event caused the Continuous Miner to trip power on the GB gas sensor and the development crew withdrew from the area.
Hand held Gas Detector at the continuous miner recorded peak readings of 3.1 and 1.9% CH4.
The outbye general body gas sensor at the dogleg read a peak of 0.43% CH4.
The internal Methane monitors in the Auxiliary fans recorded peak readings of 3.3% and 2.2% CH4 respectively. Ventilation at working face with both aux fans running was 28m3sec
