"It's a stunning bush track. You're into mature coastal forest almost immediately, with the first [of several] waterfalls after just 200m," he says. "We're keeping to the exact line of the original track, but there are a lot of places the benching has slumped away or been buried. You can sometimes spend a day on a spade and only complete a few metres."
New Zealand is unique in the scale of environmental guardianship undertaken by individuals. Numerous wildlife sanctuaries exist on private land and volunteers work tirelessly on maintenance and predator control programmes for the Department of Conservation. December 2015 saw the completion of the 85km Old Ghost Road near Westport, a nine-year commitment that galvanised more than 400 volunteers to commit 26,500 labour hours. Robinson is overwhelmed by the support the Whakaumu Track rebuild receives from the Opotiki community.
"We've had more than 40 different people helping out altogether. Some have only come once or twice, but there's a core group who are very committed. You'll go up there for a ride and find that another section has quietly been finished off."
Ron and Nancy Campbell are key volunteers who bring valuable experience to the project. Ron built many of the district's road bridges in the 1960s. Now in his 80s, he still uses a spade and grubber to good effect and led construction on the many creek crossings. In the 1990s, Ron and Nancy devoted weekends to resurrecting the badly degraded Pakihi Track, now one of the most popular mountain biking routes in the area.
Local businesses have contributed to the project, supplying materials such as culverts and signage.
"A local orchard owner held a front lawn fundraiser called The Barking Dog Orchard Concert. They raised over $250 which they donated to the track. Some of our volunteer track workers have paid for timber - we've had all kinds of people come forward and help."
Currently half the 9km track has been completed. Robinson is excited about sharing a piece of the area's history with visitors - and realistic about the work remaining.
"There's a long way to go. It's a huge mission but it's worth it. It's good fitness for us, too, walking 5km with tools and a pack, using a spade for five hours, then walking out. One of the guys said the other day 'it's addictive'."
Motu Trails
What: Mountain bike and tramping trails
Where: Opotiki, Eastern Bay of Plenty
For more information: www.motutrails.co.nz