The Department of Conservation | Te Papa Atawhai has recently been working on an ambitious project in Taranaki — replacing an ageing 16-bunk hut with a new larger hut with space for 34 bookable bunks that will provide space for more visitors to walk the Pouakai Circuit. With the remote location and poor ground conditions making a conventional foundation difficult, the DOC team turned to the StopDigging Groundscrew system to meet foundation requirements. 

The new hut is part of a larger project called The Taranaki Crossing, where Ngā Iwi o Taranaki, DOC and Kānoa (MBIE) are working together to improve partnership with iwi and cultural expression, while enhancing the economic and tourist potential of the area. The project involves connecting and upgrading a network of 25km of walking tracks to create a mix of short walks, day walks and the foundation for a multi-day walking experience at Taranaki Maunga. Track improvements have also helped protect alpine flora and fauna, including important ecological sites Ahukawakawa Wetland and Pouakai Tarns — ultimately enhancing the visitor experience while also limiting the impact of visitors to this beautiful location. 

“The Pouakai Hut project is on a really challenging alpine site, about 1200m from sea level, with incredibly high wind loads at the top of the Pouakai range in Taranaki,” explains DOC Structural Engineer, Jacob Borchers. “We normally build quite simple buildings — timber boxes that suit this environment, but for this project we partnered with local iwi and hapu for the design, and they wanted something a lot more ambitious and significant.”

The new building was to be constructed on the old hut platform, but when the team did their initial ground investigation works, they discovered poor ground conditions that would pose a significant challenge. “The ground was uncompacted fill, really poor soft ground,” says Jacob. “So we had quite an ambitious building on a challenging alpine site and the ground was about as bad as it could be.”

Adding to the challenge, the DOC team had to factor in transportation of equipment and materials — with the site only accessible by helicopter or foot. 

Initial calculations based on the design, ground conditions and wind loads ruled out the use of timber and concrete piles due to weight and transportation limitations. “For the entire site we’d have needed 250 tonnes of weight in structure,” says Jacob. “To fly that up would have been three days flying — so there was a big environmental impact as well as the weight. It was unfeasible to build using conventional piles, so we turned to StopDigging and their groundscrew system.” 

In total 340 StopDigging SGC Ground Screws ranging from 2000mm to 3000mm were specified, along with 340 bearer brackets to provide foundations for the full building as well as decking and retaining walls. The StopDigging team provided support throughout the project — including load testing onsite, and assisting in problem solving to overcome the difficult ground conditions. 

“Ground screws provided a solution that seemed ideal for this project versus traditional timber/concrete techniques,” says DOC Project Manager Wayne Boness. 

“The local Stop Digging team have provided very good support, from the initial test installs that were undertaken during the planning phase, through to the installation of the piles for the project,” he adds. “They have worked with the main contractor to meet the foundation design, and looked for solutions when problems have been encountered.” 

“One challenge was to design the structure so that if a screwpile hit a boulder during install, StopDigging could move that screwpile along a few metres and install it again,” explains Jacob. “We overcame that by oversizing all the bearers so they could move screwpiles as needed to suit site conditions.”

The StopDigging system was successful in reducing weight to simplify the transportation of materials and equipment. “With the screw piles, a 1.7 tonne digger could be lifted by helicopter and was of a manageable size on the site for getting around with minimal impact while undertaking the installs,” says Wayne. “The ability to hand and machine install the screw piles has also been of benefit on this site given the sloping nature.” 

The speed of installation using StopDigging’s system provided a big benefit for project. “On a site like this, you’re picking the odd good day between rain and high winds, so your windows are short,” says Jacob. “They did the install incredibly quickly.”

And the system minimised groundworks and holes on site — keeping both contractors and local kiwi safe. “Health and Safety was important, traditional methods would have seen a site requiring more than 250 holes to navigate around for workers,” says Wayne. “Open holes would have also provided trap hazards to the local kiwi population. The screw piles removed this hazard.”

Ultimately, the StopDigging groundscrew system provided a smart solution for the project — reducing weight and overcoming the significant weather, ground quality and transport challenges to provide a foundation for the ambitious new hut. StopDigging are expected to return once more to site to install the final piles for access stairs, with the hut scheduled to open in June 2025. 

“To date we are pleased with the result,” says Wayne. “The speed of install to get out of the ground has helped the project stay on track within our expected timeframe despite some indifferent early summer weather.” 

“It couldn’t have gone better,” adds Jacob. “I’d definitely be keen to use them in the next hut that I build. It seems to be the perfect solution assuming the ground is suitable.”