P1 Permitted Explosive Use and Gas Readings in LW 102 Tailgate 20th February 2018

MRE – Grosvenor Coal Mine – 20.02.2018.pdf

During the unannounced Inspection on the 20th February, Inspector Marlborough also raises letter from Chief Inspector stating P1 Explosive not to used to fire coal in a coal mine and to be implemented immediately.

Marlborough inspects the Control Room and makes observations about methane drainage system including capacity and construction.

Notes that production not taking place due to “the Longwall was stopped at the time due to Methane greater than               in the TG and the shearer was stopped awaiting  gas levels falling below 2% GB”

I raised the letter issued by the Chief Inspector on Friday 16 Feb 2018 regarding the use of

PI Permitted Explosives in an underground coal mine. I explained that, as per the letter,

Inspector Brown will be contacting each underground SSE regarding the letter.

I also explained that the use of PI Permitted explosives was not authorised by the chief inspector of explosives for use in coal mines to be used in coal This must be implemented by mines  immediately,

Control Room

I went into the control room. I observed the goaf drainage monitoring screen which showed  the active goaf wells and the horizontal goaf hole draining the goaf of LW102. The  monitoring showed the flow from each individual hole and the gas levels in each hole (CH4, 02, CO and C02). Mr Griffiths pointed out the last two holes immediately behind the LW face that had not yet come on line.

This was causing Methane issues in the TG and although  they had not had any incidents with Methane exceeding 2.5%, the Longwall was stopped at the time due to Methane greater than               in the TG and the shearer was stopped awaiting  gas levels falling below 2% GB. I observed the Methane trend for the previous 2 weeks and it was apparent that methane level in the TG was rising as the LW got further and further away  from the last active hole.

Mr Hawkins explained that the holes were drilled 20 m above the seam roof every 50m. They were cased with 9 5/8″ steel casing. The capacity of the goaf plant was 12,000 1/s and current goaf drainage was running at approx. 4,000 1/s. He also explained that the mine was about to trial a “floating” casing in these holes to prevent necking off of the goaf holes

This methane HPI was reported to Inspector Gouldstone