Transmission Gully

Cardno employee standing in gully

This large infrastructure project involves the construction of a 27km highway between Mackays Crossing and Linden through the Transmission Gully. Cardno was engaged in delivering landscape, survey, GIS and environmental/ecological services.

The Cardno team have been involved with Transmission Gully since 2016.

Cardno NZ assisted with surveying, developing and setting out bulk earthworks, road cut/fill batters, and drainage culverts in the preliminary stages. Topographical surveys of earthworks excavation, maintaining and updating 12d files of earthworks were used to calculate volumes. Providing machine control setting out files for earthworks machinery, uploading to machinery and calibration checks of machinery.

The Cardno NZ spatial team provided GIS support for consenting and compliance monitoring. They also developed and maintained a GIS database of stream features and proposed structures for the Transmission Gully and Porirua Link Roads projects. The database was used to determine mitigation requirements for stream impacts using a Stream Mitigation Requirement Model developed in Python. Mitigation results were presented in a customised web viewer. Cardno provided quarterly summary tables detailing actual and planned stream impacts. In addition, Cardno Spatial developed and maintained an online mobile application for site inspections of planting areas to assist the LITA inspections, including plant species, plant numbers and plant health.

To meet consent conditions, the Transmission Gully needs to mitigate 560Ha amenity planting and re-establish the surrounding land into new and restored ecosystems. The Landscape Architecture team at Cardno NZ was engaged in 2016 as Landscape Testing Inspection Authority (LITA). This highly significant landscape project will require the planting and management of approximately 3.5 million plants. Since the engagement, LITA continued to maintain a high standard of quality audits to ensure successful plant survival and canopy coverage rates overall to maintain and support the ecologically sensitive landscapes.

The project also features the most comprehensive package of ecological mitigations ever seen in a New Zealand transport project. Our ecology specialists at Cardno NZ work on location and partnership with key stakeholders to document the existing environment, fish relocations, stream restoration, biodiversity offsetting and monitoring. In less than ten years after the new motorway opens, the water quality and surrounding environment are expected to be in a better state than before the highway was built.