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Hoon Hay Wetland Basins & Outlet Structures

Halswell, Christchurch

January 2021 - Current

Christchurch City Council

Overview

GSL are undertaking two large land drainage projects for the CCC in the Hoon Hay Basin. The first is the installation of Hoon Hay Basin outlet and Cashmere Stream control structures. The second is the construction of two wetlands and a first flush basin in the Hoon Hay West Basin. This forms part of a large integrated stormwater system providing flood storage and water treatment.

Hoon Hay Wetland Basins & Outlet Structures

Project Scope

  • Site clearance, including removal and disposal of existing vegetation, stormwater structures, fences

  • Setout and survey of works. 

Hoon Hay Basin Outlet: 

  • Construct inlet weir and outlet structure 

  • Install high and low-level siphon pipes. 

  • Construct associated bund and spillway earthworks

  • Complete all ecological works including fish salvage associated with the stream diversions 

  • Undertake a local diversion of Quarry Road Drain 

  • Undertake a local diversion of Cashmere Stream. 

  • Permanent filling of land outside of the basin’s footprint 

  • Landscape planting, grass sowing and establishment. 

Hoon Hay Basin West: 

  • Earthworks to form two 1.5 hectare wetland cells and perimeter bunding 

  • A small first flush basin, and drainage channel realignment along the southern boundary

  • Filling of the southwest portion of the site

  • Culverts and weirs installation at the wetland basin inlet, outlet and connection points 

  • Construction of service vehicle access tracks. 

Take a look:

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