Winstone Aggregates General Manager David Welsh is proud of what the team has achieved.
“We’ve shifted extraction from one pit to another in a relatively short space of time. This was a massive undertaking. Now we’re in full production in Symonds pit, but we maintained our every-day high level of production throughout.
“Hunua is our largest quarry and the third largest in the country – it produces enough per annum to fill 800 Olympic swimming pools.
“Of this, around a third is premium and used in concrete, chip and asphalt for roading, with the rest being other construction and roading fill materials. We sell around a third of our total to Fletcher Building companies with the rest going to external customers,” he says.
Alongside the physical transformation of the site, Hunua has made improvements to its customer service.
“We’ve done a lot of work to reduce truck turnaround time and improve service levels in general for our customers,” he says.
“Since we installed a third weighbridge away from the main traffic flow, trucks are in and out in around 11 minutes on average. Sales staff do a lot of planning to determine which products need to be made, when. Customer satisfaction has improved showing this customer focus is really paying off.”
Hunua recently invested $2 million in new and additional mobile crushing equipment, which is a leap forward in terms of technology and efficiency.
“The new mobile crushing plant means we can make high-end roading products to order much faster – it also frees up capacity on the main plant during peak demand periods, so we have even better availability of all products for our customers,” says David.
Hunua’s large fixed plant runs 18 hours per day with its laboratory operation running equally long hours.
Then there are the excavators, dump trucks and wheel loaders – a heavy vehicle fan’s dream come true.
The main excavator, a Komatsu PC 1250, has a 578kW engine and an operating weight of almost 120,000kg. But despite its size, it’s a top ride with enhanced comfort for the driver and low vibration. Its hydraulic 45° retractable stairway makes for safer access too.
The mine plan and earthworks programme that saw the wind-down of the old pit and the start-up of Symonds pit was an impressive one. The rock resource at Hunua is greywacke, and the pit design was key to provide access to the different grades of rock – weathered, moderately weathered, and premium.
Next year, there are big plans to open up the western side back towards the fixed plant.
But first, four hectares of bush around the pit need clearing and the team will undertake a gecko salvage operation. At night by spotlight they will look for geckos such as the Auckland Green Gecko and Forest Geckos. Any Geckos found will then be relocated to Tiritiri Matangi, where they are trying to establish the species.