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Groundwater Diversion Consent Application

In 2001 a regional consent authorising take and use of groundwater from the Hunua pit was granted for a volume of up to 475 m3/day. This was to dewater the pit as it was excavated below the regional groundwater level, and to provide water for use in site activities such as aggregate processing and dust suppression.

In 2005 the consent was varied to authorise an increase in volume to 2000 m3/day and to extend the monitoring being undertaken.  Three more boreholes were added to the network of existing bore and stream locations being monitored in the vicinity, to verify that as predicted and assessed no adverse effects from dewatering would occur as the regional groundwater surface was lowered.

To enable completion of the excavation of the Hunua pit from it’s current floor level of about RL 43m (above sea level) to RL -5m, resource consent to divert up to an additional 3100 m3/day has been applied for, as a consequence of the additional ground water that will be intercepted as the pit is lowered.

The 2005 consent will remain current, which means none of the additional groundwater volume is needed for use on site, and it will simply be discharged back in to the environment via Hays Stream to the north of the site.

Provided consent is granted, the monitoring network will be extended again, with up to 8 new boreholes drilled, each with 2 piezometers, and a further 6 private bores are now also being regularly monitored.  Similarly up to 5 new stream flow gauging sites will be added to the monitoring network.

The application for consent is a two volume document. Volume 1 contains an Assessment of Environmental Effects, an Executive Summary and appendices, and Volume 2 contains the specialised technical reports which are the scientific and engineering assessments summarised in the Assessment of Environmental Effects.

These documents, and others related to processing of the consent, including:

  • Auckland Council’s request for further information in accordance with section 92 of the Resource Management Act
  • Winstone’s s92 response, and information provided
  • Auckland Council’s report and independent commissioner’s decision that the consent be processed non-notified

may be viewed by following this link. The page at that link also has a number of FAQs posted which are intended to explain some of the consent process and technical matters in “plain” english.