City Rail Link

Emissions, pollution and waste

emissions, pollution and waste


A key objective for the CRL is to make sure its construction and operation not only minimises any negative impacts to the surrounding environment, but also provides positive benefits.

Water quality

Digging holes means dealing with groundwater. To make sure that water is suitable for discharge into the stormwater system, our contractors use a number of water treatment devices to remove sediment. In response to kaitiakitanga principles, Contract 2 partner Connectus have specified ‘non-chemical’ biodegradable flocculants to assist with the removal of sediment from water. The product is safe to handle for staff and because it’s biodegradable it is better for the environment when the water leaves site.

Post construction, street trees will be planted in Albert Street. As an approach to improve the quality of the water that enters the Waitemata Harbour these street trees will act as ‘bio-retention devices’. This approach diverts the ‘first-flush’ rainfall directly into below-ground tree-pits that contain the tree roots. Not only does this significantly reduce the need for watering, saving hundreds of thousands of litres of water a year, but it also improves the quality of the water running into the stormwater network and the harbour. The trees are able to filter out contaminants washed off the road when the rain first starts falling.


Noise and vibration

Noise and vibration tend to go hand-in-hand when building such a large piece of infrastructure, but the CRL is doing as much as possible to minimise the impact on our neighbours.

A large acoustic shed was established on Victoria Street to reduce the disturbance to local businesses while a tunnel boring machine was used to construct a new stormwater main. Powering the machine with grid electricity rather than a diesel generator further reduced noise, as well as eliminating diesel fumes.

Where noisy work is undertaken outside this area, acoustic barriers are used to shield passers-by and local businesses from noise, and monitoring is constantly undertaken.

It is crucial that vibration and settlement does not cause damage to nearby structures, especially heritage buildings. The project is using the Cyclops monitoring system, which is used on similar projects around the world. Using laser targeting, Cyclops monitors the ground surface and buildings for any displacement or movement. The system is accurate to within one millimetre. Before construction, adjacent buildings have also been surveyed to provide a baseline for comparison.

NOISE: Monitoring undertaken during demolition works at Britomart Station

NOISE: Monitoring undertaken during demolition works at Britomart Station


Construction and demolition waste represents a significant portion of Auckland’s waste to landfill and minimising this is an industry-wide challenge. In response to this challenge, and in line with Auckland Council direction, CRL is striving to send zero waste to landfill during construction by supporting and challenging our contractors to avoid, reduce, reuse, recycle and recover as much waste as practicable.

Designing for waste minimisation is a priority to support this aspirational goal, and the contractors' waste avoidance and resource recovery plans are essential.

Contractors are asked to identify:

  • Likely sources of waste and when they will arise
  • Strategies for implementing the waste management hierarchy (avoid – reduce – reuse – recycle – recover – treat – dispose)
  • Systems to monitor and report on waste
  • Predicted quantities and diversion paths

This has resulted in a number of initiatives, including:

  • Sending mixed waste to Green Gorilla's purpose-built Resource Recovery and Transfer Station where treated timber is re-purposed into biofuel by processing it into chips which replace coal in Golden Bay Cement’s furnaces, and other waste is separated for recycling.
  • Sending demolition concrete to Green Vision where it is crushed to be used as aggregate
  • Working with Marley to recycle uPVC pipe
  • Re-purposing the KiwiRail kiosk at Britomart station into an information kiosk
Green Gorilla on site

Green Gorilla on site

Water feature piping being recycled at Marley yard

Water feature piping being recycled at Marley yard

KiwiRail kiosk re-purposed

KiwiRail kiosk re-purposed