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Puhoi to Warkworth Motorway

This project realigns the existing SH1 between the Northern Gateway Toll Road (NGTR) at the Johnstone’s Hill tunnels and just north of Warkworth


The alignment will bypass Warkworth on the western side and tie into the existing SH1 north of Warkworth. It will be a total of 18.5km in length. The upgrade will be a new four-lane dual carriageway road, designed and constructed to motorway standards and the NZTA RoNS standards.  Acting as an expert in erosion and sediment control for the Alliance, Ridley Dunphy Environmental Limited  (RDE) developed the full Construction Water Management Report for this project.  With steep terrain and sensitive environments, RDE developed a unique methodology whereby focus areas were studied in detail and specific erosion and sediment controls were developed for these.  This in turn linked to sediment generation calculations, mass haul details, environmental downstream freshwater and coastal effects and adjustment of the erosion and sediment control to achieve the necessary outcomes.  Working with a range of experts was a critical part of the project development.  Consent conditions were developed with flexibility for the contractor while ensuring the effects of the earthworks were appropriately managed.  RDE was the primary expect in writing the Construction Water Management Report, giving evidence to the Board of Inquiry and reviewing the draft decision and associated conditions.