The Pike River Recovery Agency (PRRA) is continuing preparation for re-entry to the mine in early May to recover the drift. 29 miners are believed to have died on or around 19th November 2010 following a series of gas explosions at the mine.
The re-entry to Pike River mine has been a long journey for families of the miners who have sought justice and closure since the disaster but there remains a vast array of technical challenges for the re-entry plan.
Pike’s 2.3km drift access tunnel is located in the Paparoa Ranges, approximately 45 minutes from Greymouth in New Zealand. While the drift recovery exercise is aimed to facilitate a further police investigation of the Pike River Mine, the challenge for the agency is to complete the important exercise safely with the world watching.
PRRA says that ‘findings will provide valuable information that may assist in the operations of other underground ventures.’
Ventilation plan will aim to ensure fresh air re-entry
The PRRA plans to re-enter the drift in fresh air through the development of an integrated ventilation plan that involves inertisation of the mine working with nitrogen and the use of a strategically located venturi coupled to a borehole (borehole 53) to maintain positive pressure in the drift. The PRRA is currently developing a range of Trigger Action Response Plans (TARP) associated with the re-entry and has engaged Australian ventilation and spontaneous combustion expert Dr Basil Beamish to assist with preparations for re-entry.
Pike River site under scrutiny
Worksafe NZ is also carefully monitoring the activities of PRRA in view of the risks associated with re-entry and recently attended the site for inspection and discussions regarding ventilation. Worksafe highlighted in a mine record entry that ‘PRRA could not articulate what the absolute pressure would be within the mine and at the mixing point where the nitrogen/methane mix integrated with the fresh air and was drawn upward by the venturi. There needed to be checks done to ensure that barometric pressure would not overcome the absolute pressure’
PRRA advised this week that ‘The site is currently installing pipelines for the compressed air to operate the venturi which will be attached on borehole 53’ The pipelines are being flown up the hill, then dragged into place and coupled up to the venturi. The venturi is one component of the mine ventilation system and will be used to ensure positive pressure in the mine drift during the staged re-entry.
Additionally, the PRRA has worked with stakeholder groups to develop an engagement strategy around the culturally sensitive Pike River/White Knight Stream which runs next to the portal. The stream is sacred to Ngati Waewae iwi people.
The PRRA and Family reference group will also work with the Department of Conservation and iwi to establish a memorial on the site including a ‘Pike 29 Memorial Track’.
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