Hunua – birth of a new quarry

For 89 years Hunua Quarry has been supplying high quality aggregate to the Auckland region, but it’s nearing the end of its operational life and Winstone Aggregates is busy bringing its successor online.

Geological and groundwater constraints limit the further expansion of the existing Hunua pit, but land adjacent to the exiting pit bought back in the 1950s will mean that a new pit can be fully operational by the time the current Hunua pit closes its doors to quarrying.

Although this is still a few years off, there’s a whole lot more to it than just digging a hole!  The consent and mitigating process for the new Symonds Hill site was only the beginning. Replanting, pest control and the rehousing of native species has been going on for several years now, and last year a 20 metre wide 1 km long haul road was built.  This road has to be strong enough to last over 35 years and to cope with trucks carrying unprocessed rock from the rock face of the new pit to the existing processing plant.

We’re now looking at starting to excavate and form the quarry benches.  Investigations of the resource have been ongoing, but our first job is to remove the overburden of clay and weathered rocks that lie on top of the blue rock – or Greywacke – that lies beneath.