Top of the class

To those of us who call Aotearoa New Zealand home, it’s probably not surprising to learn that our wee slice of heaven is in the top 50 countries in terms of rainfall. In fact, it’s the 42nd wettest country of the 186 that measure their annual rainfall.

While all that ‘liquid sunshine’ keeps us lush and green, it can also play havoc when it comes in the form of a deluge, as the residents of Taupō found on Wednesday, 25 November, 2020, when 25mm of rain fell within a few hours.

That may not sound like a lot, but when you extrapolate that out, it’s the equivalent of more than 85,000 litres per acre.

Even less surprising, then, that that much rain can do some pretty significant damage.

“One of the hardest hit communities in the town, was that of Tauhara College, which was forced to close the majority of its facilities and send its students home for the remainder of the school year,” says Jude Hickson, Managing Director of Stop Digging.

“A plan to get the school back up to full operation for the first day of first term 2021 was put into place and saw 18 new prefab classrooms and accompanying ablution blocks installed,” says Jude.

“Livingstone Building was employed as the contractor tasked with carrying out the construction programme, which included traditional pile foundations for all of the new buildings. It soon became apparent, however, that a more expeditious approach was needed and so the project manager reached out to Shane Virtue of Stop Digging Waikato to provide the solution.

“Shane was able to propose a workable solution that included the installation of more than 500 ground screws as foundations for the classrooms and ablution blocks.”

As the team set about placing the ground screws, work began on installing the ‘traditional’ foundations as well.

“I’m always quick to proclaim the benefits of ground screw foundations, but it was a really interesting experience being able to compare firsthand just how effective a solution they are—massively faster and cleaner than digging and concreting. This really brought home to me that ground screws were the right solution for this project.”

Ground screw foundations: for a more sustainable construction industry

“In construction, any process that offers real efficiencies is always going to be the preferred process. The ground screw system is, hands down, the more economical foundation process, for a number of reasons—it’s not weather dependent, therefore eliminating any costly weather delays associated with concrete; creates absolutely no mess, meaning there’s no need to cart fill away from the site; and, ground screws are ready to take load instantly, so, as was the case with Tauhara College, the buildings could be installed the same day as the foundation was installed.

“Additionally, ground screws also offer the chance to massively reduce the carbon footprint of foundation construction—both in terms of the product (steel) used in their manufacture and by doing away with the need for heavy plant for installation. And, if you need another reason, they are incredibly sustainable; being removable and reusable with zero ground disturbance.

“Ground Screws were definitely the right solution for this project as it is intended to be a short-term fix, however, the ground screws could be there for 100 years if needed.”

Ground screw foundations: ready when you need them to be

“One of the challenges faced by the contractor on this project was the tight time frame. Essentially, they only had the summer holidays to get the new buildings installed and ready for use—requiring all of the associated stakeholders, ourselves included, being able to turn around their part of the process quickly and efficiently.

“Despite the short notice with this project, we are very lucky to have an extremely robust supply chain, which ensures product is always on hand and ready to be transported to anywhere in the country. Of course, it also didn’t hurt that this was not a complicated project at all and only required a minimum of site appraisal.”

Jude says a further planned stage of the project will see prefab buildings being sited on top of existing concrete courts, however, thanks to the ground screw foundations, if at some future time the buildings are removed, the courts can be easily and cost-effectively reinstated.

“This really is the way New Zealand should be doing pile foundations; they are an ideal solution for a range of applications—house and deck foundations are our core work, but we’re also working on a boardwalk project in Auckland; a large master-planned development, also in Auckland; and, we have an exciting library project about to begin in Motueka.

“Stop Digging can also provide, through a third-party structural engineer, full producer statement—PS1, PS4—documentation, taking some of the additional rigmarole out of the consenting process for clients.”

Learn more about the ground screw foundation system and how to specify it for your next project.