By Lee Scanlon of 
The Tawhai Tunnel crew celebrates the end of the tunnel repair project. Photo: Supplied
Bathurst Resources plans to resume railing Stockton coal to Lyttelton on Sunday, when the 134-year-old Tawhai Tunnel near Reefton is due to reopen.
The tunnel closed in June after a digger operator working on track renewal noticed the tunnel lining was crumbling.
Since then, Bathurst has had to truck Stockton coal to Ikamatua, near Blackball, for transfer to rail. The coal trucking has annoyed some residents and damaged several roads, including State Highway 6, the Lower Buller Gorge.
Bathurst's export operations manager Ian Harvey said he was relieved railing could resume. "And I'm sure there will be a lot of people in Westport, Reefton and Granity that will feel the same way."
Harvey said Bathurst expected to end the trucking on Thursday morning.
The number of coal trains would then increase from 19 a week before the tunnel closed, to 21 a week, to move coal stockpiled at Stockton.
"We've got some fairly large stockpiles of coal that we can start to push through, to accelerate during the second half (of the financial year)."
Stockton Mine, near Westport, is operated by Bathurst Resources. Photo: Supplied/ Bathurst Resources
Each train carries almost 1500 tonnes, so the extra capacity will increase the weekly total from about 28,000 tonnes to about 31,000 tonnes.
The peak weekly tonnage for trucking was well below that, at 19,000 tonnes.
However, Harvey said trucking had enabled Stockton mine to retain all its staff and meet its export orders, with some juggling of shipments.
Stockton's exports would end up down about 100,000 tonnes on the plans for the financial year, he said.
Complex repair project - KiwiRail
KiwiRail South Island regional infrastructure manager Gary Ikin said the rail transport operator had undertaken a large complex construction project to fix structural problems in three sections of the Tawhai Tunnel. The rebuild had been a "massive undertaking" for the 70 workers.
"The tunnel team have been working in cramped, difficult conditions for months and have maintained a solid focus on safety and delivering the work quickly. About 50,000 hours has gone into the repair, with much of it happening 24/7.
"We're leaving the tunnel stronger than it was and have significantly improved drainage. This will help reduce the risk of future disruptions."
Work in the 370-metre tunnel had included:
- Robotic machines sprayed about 951 cubic metres of concrete to strengthen the lining;
- 886 rock bolts installed to secure the lining to the surrounding ground;
- about 374m of modern concrete tunnel lining and modern track bed drainage installed.
Return of rail service comes with warnings to look carefully at crossings
Ikin said the resumed rail services would run seven days a week.
"Not only does it mean trains will be running again from Ngakawau, but they will be running more often over the coming months as we move the export coal backlog for our customers.
"There are 30 public level crossings and numerous private level crossings between Ngakawau and the Tawhai tunnel, and it has been almost eight months since freight services have run in the area.
"We urge everyone in the Buller community to be extra vigilant and cautious any time they approach a rail level crossing. Always obey signage and always take a good long look in both directions before crossing the tracks."
Ikin thanked KiwiRail's customers, the Buller District Council and Buller people for their patience and support during the last eight months. He said the trucking had put a lot of pressure on local highways. "We recognise the inconvenience this has caused and appreciate your patience with us."
KiwiRail declined to reveal the cost of the tunnel repair, citing commercial sensitivity.
A spokesman said KiwiRail had engaged specialists to investigate the cause of the tunnel collapse and was addressing the findings of the investigations.
"We are not releasing any findings at the moment, as they are commercially sensitive."
* This story originally appeared in the Westport News.
