Court hears of bleak chance of escape in mine
The remote chance of escape for survivors after the Pike River coalmine explosion has been spelt out in a court case against the mine's former owners.
A two-day hearing finished today in the Greymouth District Court on Pike River Coal Ltd's alleged health and safety failures linked to the November 2010 blast that killed 29 men.
The former Labour Department, now part of the Ministry of Business, Innovation and Employment, laid nine charges under the Health and Safety in Employment Act against the company (in receivership).
They related to methane, strata and ventilation management, mitigating explosion risk and impact, and health and safety management for contractors, subcontractors and their employees in the underground West Coast mine.
Each charge carries a maximum penalty of $250,000.
Two expert witnesses told the court today that the mine had insufficient smokelines or lifelines, used to lead miners to the exit during a fire or explosion.
"Underground mines have no natural light and the disorientation and loss of visibility after an explosion or as a result of smoke may be extreme," ministry health and safety inspector Jane Birdsall said.
Two days before the blast, a mining deputy had complained that the smokelines were in "very poor condition" and needed checking.
"They were either absent, incomplete on the floor or at a height where they were difficult to reach," Birdsall said.
Australian mine safety expert David Reece said smokelines represented good mining practice and increased the prospects of survival by giving personnel a chance to quickly get out of the mine.
The pair criticised the mine's fresh-air base.
Birdsall said Pike's sole fresh-air base was at the end of the mine's 2.3-kilometre tunnel and excavated in coal, despite being needed as a longer-term refuge by anyone unable to climb 102 metres up the ventilation shaft, the only emergency exit.
"It was not lined with an incombustible product such as shotcrete. [It] could, therefore, burn," she said.
Reece, who also gave evidence at the royal commission of inquiry into the tragedy last year, called Pike River's fresh-air base "woefully substandard" because it contained the methane drainage line, a combustible source of fuel, had no separate air supply and its brattice seal was not explosion-proof with no air lock.
"In a coalmine, you don't want to stay there [after an explosion] because there is an awful lot of coal that can burn for an awful long time. The rationale is get out and keep going." he said.
The witnesses also criticised Pike River for placing its main ventilation fan underground, which they deemed unsafe because of the possibility of damage from explosions, problems with power supply in gassy atmospheres and inability to guarantee access to the backup surface fan.
Birdsall said the backup fan was badly damaged in the blast and stopped working.
Its explosion protection was less than half the size it should have been.
"A key step towards recovering a mine after an explosion is the continuation of underground ventilation," she said.
"This enhances the chances of evacuation or rescue of any person who survived the explosion, makes re-entry safer and helps control the subsequent buildup of methane and secondary explosions."
No recovery effort was mounted at the mine after the November 19, 2010, blast because it was deemed unsafe.
Reece focused on Pike River Coal's inadequate methane and ventilation management, which he said were the "two hallmarks" to managing underground coalmines.
Failures included inadequate methane draining and inadequate methane monitoring and gas sensors.
"There needed to be a greater level of oversight on gas monitors regarding recognising there was something wrong. They are things that should not go unnoticed for long periods," he said.
A ventilation expert for the ministry worked out that the mine's methane levels would have reached the explosive range at 7 per cent for 10 minutes only two days before the first blast.
Judge Jane Farish adjourned the hearing until April 18 to deliver an oral verdict.
Last July, the company's lawyer told the court it would not defend the charges and would take no part in the legal process other than appearing at sentencing if charges were proved.