Centreport, Wellington, Aotearoa New Zealand
Landscape Architect : Wraight + Associates
Architecture : Studio of Pacific Architecture
Client : Centreport Wellington Limited
Project Status: Completed
CentrePort’s development master plan embraces environmentally responsible and responsive design. Given its proximity to Wellington Harbour it is appropriate that the development implements an integrated water management strategy that moderates water quality and quantities leaving the site.
Water Sensitive Urban Design Guiding Principles
The guiding principles of WSUD are centred on achieving integrated water cycle management solutions for new urban release areas and urban renewal developments such as CentrePort’s harbour’s edge site linked to an ESD focus aimed at:
• reducing potable water demand through water efficient appliances, rainwater and greywater reuse;
• minimising wastewater generation and treatment of wastewater to a standard suitable for effluent re-use opportunities and/or release to receiving waters;
• treating urban stormwater to meet water quality objectives for reuse and/or discharge to surface waters; and
• using stormwater in the urban landscape to maximise the visual and recreational amenity of developments.
Best practice urban stormwater management aims to meet multiple objectives including:
• Providing flood conveyance.
• Protecting downstream aquatic ecosystems.
• Removing contaminants.
• Promoting stormwater elements as part of the urban form.
A fundamental requirement of a stormwater system is to provide a conveyance system for safe passage of stormwater runoff to avoid nuisance flooding and flood damage to public and private property.
The WSUD strategy for CentrePort focuses on the implementation of bio-retention swales, rain-gardens, bio-retention tree pits and roof water storage ponds.
Are densely planted linear wetlands that occur within several of the street reserves site wide. ‘First-flush’ stormwater run-off, the earliest and subsequently the most polluted component of rainfall, is directed towards a densely planted swale located either in the median or at the road edge. The swales have capacity to detain and filter run-off. The hydro-static pressure created by the detained water forces water to filter through the bio-medium(soil). Microbial activity within the soil and attached to plant roots removes hydro-carbonate contaminants and other pollutants from the runoff. Plant roots ensure this medium remains porous and free-draining whilst providing a barrier to larger particulates. Clean filtered water flows into slotted agricultural drains at the base of the swale and is then conveyed off site. During a big storm event excess water overflows into a raised sump, less polluted than ‘first-flush’ run off this water is conveyed directly into a conventional stormwater system.
Operate in a similar manner to bio-retention swales but are not relegated to a linear form tending to be discrete non-continuous interventions. Rain gardens occur within urban plazas and laneways to both improve stormwater runoff quality and visually augment these spaces.
Bio-retention tree pits:
Working in conjunction with either swales or rain-gardens, the majority of tree pits site wide will filter stormwater run-off from roads and foot path pavements.
Roof water storage ponds:
Park spaces within the site have been designed to accommodate storage ponds for sitewide irrigation purposes. Storm water collected off the rooves of the proposed development will be harvested for this purpose. The storage ponds comprise of two main components, a shallow pool of open water containing discrete plantings and a covered deeper reservoir. Water will be reticulated between both sections of the storage system to maintain quality.
For more information on this project see Centreport