environment

DoC accused of ‘blast now, think later’ in national park

Explosives were used to blast a millions-of-years-old rock overhang in a national park. David Williams reports.

The Department of Conservation stands accused of a “blast now and think later” approach in a West Coast national park.

In July, a four-tonne sandstone block sheared off, coming to rest at the bottom of a set of stairs from a viewing platform on the Truman Track, part of the Paparoa National Park. The track, just north of Punakaiki, funnels more than 35,000 walkers a year to a spectacular coastline with cliffs, caverns, a blowhole, and waterfall.

Given the high numbers of “risk-taking” visitors, many of whom take selfies beyond a low chain-link fence, a consultant geologist recommended the residual thin section of overhang be removed. DoC agreed. West Coast firm Geotech Ltd was commissioned to do the work, using a series of drilled holes filled with explosives.

The rock overhang is described as Eocene shallow marine fine sandstone. The Eocene Epoch ended 34 million years ago.

Federated Mountain Clubs president Jan Finlayson says DoC’s response was brutal – reducing a beautiful, natural feature to rubble. Blasting the estimated the 70-tonne overhang is deplorable in and of itself, she says, but also for the example that it sets, considering it was done in a national park, and it is listed as a geo-preservation site, as well as a registered archaeological site.

“The blast now and think later approach, the Acme Corporation approach, is completely unacceptable from the organisation that is charged with the land’s care.”

The four-tonne block fell about two metres, right next to a set of steps. Photo: DoC

It’s another example of the department putting tourism above nature, after Newsroom’s story, last week, of healthy trees being cut down in the Arthur’s Pass National Park. (Last year, complaints were also made to DoC’s Arthur’s Pass office for excessive track clearance in the Otira Valley, damaging fragile alpine plants.)

Given DoC has been running a national programme to assess general hazards on tracks ahead of the coming summer season, these stories are probably just the tip of the iceberg.

Finlayson, of FMC, says: “This crystalises many of the issues that we have with the Department of Conservation, and its seemingly scattergun approach to public safety issues.”

Buller operations manager Bob Dickson says in an emailed statement that DoC consulted with engineering and geotechnical experts before the work was done at Truman Track. “It was planned and undertaken with a great deal of care in order to manage the visitor risk at this increasingly popular site.”

Dickson called the explosives “very low impact”.

Geotech’s managing director Ant Black has some sympathy for DoC, having to look after “bloody nutty”, mainly urban, foreign tourists, who often wear jandals and have no sense of self-preservation. These popular, easily accessible areas of the front country he calls “Muppetland”.

“We as a country promote it to these tourists and I guess we’re also bound to keep it pretty bloody safe for them.”

The remediated site, with rock wall, planting, and gravelled track. Photo: DoC

Finlayson says the department has a job to do, written in the National Parks Act, in its general policy for national parks, and the Paparoa National Park management plan. “They rightly call for conservation of this special place, whose beautiful sandstone overhang was carved out by the sea over a long period of time.”

She adds: “Tourism should be subservient to national park values, not the other way around.”

Her concern – one she’s raised with DoC’s director-general Lou Sanson and Conservation Minister Eugenie Sage – is that removing the overhang seemed to be the first “and only” resort, rather than the last option. (Dickson admitted in an email that building steps directly under an overhang “raises a planning fault with our initial design”. He adds: “Given the prevalence of other rock overhangs nearby, visitors need to be informed appropriately about not loitering under those sites.”)

The department’s natural instinct should be to alter built infrastructure, not nature, Finlayson says. What about moving the track somewhere else, or removing it altogether? Or using different signage?

“Even if taming so-called hazards in national parks were consistent with the law – it’s not – it wouldn’t make any sense,” she says. “The more these wild places are domesticated, the more ill-equipped people will go there, and beyond. And the more they go there, the more these places will, by the same logic, need to be domesticated.”

Finlayson says DoC has no obvious internal procedure for dealing with issues like this – that its health and safety lines seem to be randomly drawn in the sand. Perhaps what’s needed is a “supply-focused” approach to tourism, she suggests. “That is where what our land and our communities can put up with dictates what we allow.”

That might involve changing the way the country is marketed overseas, and how DoC publicises our wild lands and the facilities within them.

A "blast induced fracture" in the remaining rock at Truman Track. Photo: WSP Opus

A story about the Truman Track blasting in The Westport News prompted FMC to file an Official Information Act request. DoC classified the request as “high-risk”.

The response included the reports written by Torben Fischer, a geologist from consulting firm WSP Opus. His first, dated August 6, gave two options to DoC after the four-tonne block fell – removing the overhang or installing a rockfall barrier. Removal was preferred as the “most cost-efficient” option.

Buller-based DoC senior ranger Eric de Boer wrote to Geotech boss Black, highlighting Fischer’s recommendation that high explosives not be used, to prevent “unnecessary blast damage to the surrounding rock mass and environment” in the environmentally-sensitive area.

Black “wasn’t sold” on using non-explosive product Nxburst, however – preferring a specialist “high VOD (velocity of detonation) underground smooth wall blasting product”. Fischer warned De Boer about the risks of “overcharging” explosives, and possible blast damage to the remaining rock mass. “The key thing is to bring it down gently.” He ends the email: “Sad to see it go.”

Fischer wrote a second report after inspecting the downed rock. (DoC got a regional council consent to discharge the resulting debris onto nearby Truman Beach.) He said the blasting fractured the residual rock mass, with one three-metre-long fracture “open by 5-10mm”, and an additional three metres of cracking along a smaller, detached block.

The blast also caused “back breaking” on a weak, weathered layer not visible before the collapse. The use of high explosives “might have contributed”, the report says. “But the weak weathered layer was not visible before collapse of the overhang and the ground engineering contractor had no way of predicting this effect.”

“The primary objective of this work was to ensure the safety of visitors, and the work was professionally undertaken by experts and has not resulted in compromising the remaining rock mass.” – Bob Dickson

Black says his company’s product was better than what Fischer suggested, and the work was a technical success. “The blast went really well and there was no damage to the structure.” There was no back break where the blast happened, he maintains – rather, where the block dropped, gravels came in from higher up.

Where the four-tonne block initially fell, there was water coming through the defects on the rock face, he says – “so it was going to fall in”. “When is always the hard part. You just don’t know.”

The overhang’s removal reduced the rockfall risk to “acceptable”, according to Fischer’s second report, penned last month. He suggested the site be monitored regularly – “from a safe position” – over the next six-to-12 months.

DoC’s Buller boss Dickson says remediation work was carried out by rangers after advice from Fischer, who subsequently inspected the site and deemed it safe to re-open to the public. “The primary objective of this work was to ensure the safety of visitors, and the work was professionally undertaken by experts and has not resulted in compromising the remaining rock mass.”

Finlayson of FMC, meanwhile, mourns the lost piece of New Zealand’s natural history.

In her letter to DoC boss Sanson, copied to Minister Sage, Finlayson asked for such a thing never to happen again. She tells Newsroom: “It’s just not OK to go off half-cocked – it’s definitely not OK to do that when it reduces a beautiful natural place to rubble and rock.”

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