Willowbank Quarry is not your average quarry. While its single purpose is to produce a specific sized rock for the Transmission Gully motorway project, what sets it apart is the multiple measures in place to protect the local environment.

Located near Judgeford, north west of Wellington, New Zealand the quarry provides the Transmission Gully team a specific 40mm sized rock, termed ‘All passing’ or ‘AP40’ product.

Wellington Gateway Partnership’s CEO, Sergio Mejia says around 400,000 tonnes of AP40 will be extracted from the quarry and once processed, it will be trucked to the surrounding project areas for use in road pavement construction for the new motorway.

Rock aside, what makes this quarry unique, is the sheer amount of environmental effort that’s been put in place, making it one of the most environmentally friendly quarries in New Zealand.

Sergio Mejia Wellington Gateway Partnership’s CEO

Willowbank Quarry in numbers:

  • 400,000 tonnes of rock will be extracted for use in pavement construction
  • 40mm - the specific size of each AP40 rock used for the Transmission Gully motorway project
  • 19 - the number of lizard species found and relocated to a temporary habitat
  • 200 tonnes of rock was used to build a new habitat for the lizards
  • 250 eels were defished and relocated to suitable habitats downstream
  • 700m - total length of four new stream beds created for fish habitats
  • 26,700 native trees and shrubs planted across the quarry site.

Relocating wildlife

Before works began, ecologists were brought in to capture lizards, with 19 species found and relocated to a temporary home onsite at the quarry, out of harm’s way during construction. Around 200 tonnes of rock was used to construct a new boulder field habitat for the lizards.

Several branches of streams have also been defished with 250 eels – mainly long-fin, relocated to suitable habitats downstream within the catchment area.

Water was then diverted through a series of temporary pipes, allowing new streams to be built. Four new streambeds - totalling roughly 700m in length, provide a number of new habitats for different fish species.

Planting native trees and shrubs

This planting season, an impressive 26,700 native trees and shrubs have been planted across eight different areas of the quarry, including a new area of Kanuka forest, and the newly constructed streambeds and wetland area.

Suitable native trees and shrubs have been planted for the lizard habitat, as well as to create a screening area, providing a natural shelter between the quarry and the lower access track.

Treating water

To protect the environment further, the site has two large sediment retention ponds. These ponds capture water runoff, which is stored, and an approved ‘flocculant’ product is added to help the sediment settle out of the water.

Before water is released back into surrounding waterways, it is tested to make sure that it meets environmental compliance, which is set by Greater Wellington Regional Council.

Once the new motorway is open, the quarry will close. The quarry and its surrounding environment will then be handed back to the landowner, who will have a significantly enhanced environmental asset for the future.

About the Transmission Gully project

Transmission Gully is New Zealand’s first roading project to be procured through a public private partnership.

The Wellington Gateway Partnership has been engaged to design, construct, finance, operate and maintain the new Transmission Gully highway for 25 years.

The consortium includes Pacific Partnerships (sponsor and equity investor), CPB Contractors (design and construction), and Ventia, CIMIC Group’s 50% owned associate, (operations and maintenance).

Read more about the project here.

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