Promoting sustainability

Taking practical steps to reduce, reuse and recycle

At CI (Central Interceptor) we focus on the efficient use of resources such as energy, materials and water on reducing waste and on reusing what would otherwise be dumped.
 
As you might rightly expect from our name, Watercare is active in reducing our water consumption. We can do this by using non-drinkable (non-potable) water. We collect rainwater on site, use bore water and reuse water we’ve already used onsite for construction. In another major initiative, we are building a plant to treat and re-use wastewater from our Māngere wastewater treatment plant. This water will help run the TBM as it bores forward from our Māngere construction site.
 
As with water, using less energy is vital for us. For example, we’ve reduced driving distances of trucks carrying away our dirt and soil. We also dry this spoil on-site to reduce the weight of transported material. We also look to use electric equipment, wherever possible, rather than use fossil fuels. The locomotives transporting people, equipment and rocks and dirt (spoil) up and down the tunnels are electric battery-powered and as a result improve the air quality in the tunnel. CI is also about to introduce electric trucks for hauling tunnel spoil to Puketutu Island in Māngere.
 
For some of our construction sites we’ve had to buy land with existing houses on and subsequently remove them. Rather than the traditional smash and bash approach which involves taking all the material to the dump, we now deconstruct buildings. We systematically take them apart so most of the material can be reused. For example, from two houses in Grey Lynn we kept 91% of the material out of landfill, with the doors being sent to Tonga for reuse. Deconstruction is also quieter for our neighbours than demolition.
Photo of two workers deconstructing and recycling items rather than demolishing
Photo: Rather than demolish we deconstruct and recycle

We can’t talk about sustainability without discussing climate change: it has been a major factor in our thinking and shows in our design planning. Our designers took climate change into serious consideration in the tunnel’s design, its size, and the materials it is built from. This means that the tunnel can ride out more intense storms and cater for our city’s expected increase in population.
 

Getting an outside view of our initiatives

With sustainability now in all our planning, design and construction practices, we wanted an independent test of our work. To do so, in late 2020 we submitted our design work to the Infrastructure Sustainability Council (ISC), which grades sustainability in infrastructure projects. CI was awarded the Council’s highest design assessment, a leading rating. As we build the tunnel and shafts, we are now compiling the evidence for a rating for the construction phase of CI, with another leading rating in our sights.
Photo of Olivia Philpott, Sustainability Lead for CI and Shayne Cunis, CI Executive Programme Director, proudly receiving the ISCA Award
Photo: Olivia Philpott, Sustainability Lead for CI and Shayne Cunis, CI Executive Programme Director, proudly receive the ISCA Award

On the Central Interceptor, sustainability is a team effort, with responsibilities shared amongst those who can help achieve sustainability outcomes, such as our design, construction, environmental and procurement managers. Our belief is: Ehara taku toa i te toa takitahi, engari kē he toa takitini – my success should not be bestowed onto me alone, it was not individual success but the success of a collective.
 

Electric haulage trucks on their way

We continually look for new ways to be more sustainable with our project resources. The project is on the road to making our heavy vehicle fleet greener thanks to a $500,000 grant from the Energy Efficiency & Conservation Authority (EECA) which will be put towards buying three electric trucks.
 
Anticipated to arrive early next year, the e-trucks will transport more than 66,000 tonnes of earth from CI sites, reducing project emissions by more than 300 tonnes - that's the equivalent of driving from Cape Reinga to Bluff more than 800 times.
Photo of an e-truck battery being prepared for installation

Photo: E-truck battery ready for installation

The vehicles produce 79 per cent less carbon emissions compared to their diesel counterparts and they aren't as noisy, which will be fantastic for the teams working in residential areas. They also have lift-off battery swapping capability, meaning the trucks don't have the usual downtime while charging: they can have the battery swapped out for a fully-charged one in 5 minutes – the same time it would take to re-fuel with diesel.
 
We’re starting work to upskill our earth-moving partners, Fulton Hogan, in managing the heavy trucks. There is a four-to-six-month lead time on getting the trucks into the country but they should be on the job in early 2022.

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