We cement our work to boost the resilience of Auckland’s water supply with the completion of its first of four concrete floor pours for a new 45-million-litre reservoir at the Redoubt Road Reservoir complex.
The reservoir complex can store up to 120 million litres and more than 80% of Auckland’s treated water passes through it each day.
The addition of a third reservoir – which is currently on track to be finished mid-2024 – will increase resilience in the network, thereby future-proofing Auckland’s water supply and catering for growth.
Once completed, the $60 million reservoir will be 106 metres long, 77 metres wide, 8 metres in height and consist of 650 tonnes of steel reinforcing. It will hold the equivalent to 18 Olympic-sized swimming pools.
Our project manager Buena Van Wyk says last night’s pour – which went from 12am Sunday to 10am Monday – was all about laying the foundation for the structural work that will occur in the following months.
"Last night we poured 500 cubic metres of concrete, which is equivalent to roughly 100 concrete trucks.
"To prepare for the floor pour, our team has placed approximately 20,000 tonnes of aggregate for the foundation to help distribute the loads from the superstructure on the entire footprint."
Van Wyk says our project partners Fulton Hogan and Beca are working together with us across several projects in Auckland.
She says the following three floor pours will occur at night over the summer months.
Although much of the work to build the reservoir occurs during the day, concrete pours are done at night to ensure consistent supply over a period. Pouring during the day increases the risk of the concrete curing at different rates which could result in defects to the reservoir floor slab.
"To make the pours for the critical infrastructure less disruptive for the community, our plan of attack was to minimise noise as much as possible by installing noise reduction features, scheduling concrete to reduce waiting and idling on site, encouraging the use of RT radio and the strategic positioning of noise barrier shields."
Concrete structures like the Redoubt Road Reservoir are carbon intensive. The project team has offset its carbon emissions by adding fly ash to the cement mix and transporting clay fill from on-site to help construction works at Puketutu Island, where we are rehabilitating volcanic cones that were quarried in the 1950s, says Van Wyk.
Besides reducing Co2 emissions, the fly ash also has greater workability and robustness thereby reducing shrinkage cracks when compared to other water-based cement mixes.
"Overall, sharing fill between construction sites has helped us to offset approximately 559,000 kilos of carbon.
"Transporting fill from our construction sites like Redoubt Road to Puketutu Island not only reduces carbon emissions but respects te ao Māori value of what is given by the land should be returned to the land."