Client name: Auckland Council
Duration: January 2011 – July 2013
Location: Westgate, Auckland, New Zealand
Coffey provides the geotechnical expertise to positively affect the outcome of a bold and innovative landscape design concept for this World Architecture Festival (WAF) Award winning project.
A collaborative approach
As part of the Massey-North Town Centre development Auckland Council’s Project Development Office in collaboration with the Healthy Waters and their Parks, Sport and Recreation Departments wanted to create a project that integrated local needs with the various engineering and ecological requirements of a town centre and a wetland.
The linear reserve follows a riparian corridor and integrates community amenities with engineering and ecology. Interspersed with stormwater ponds and wetland areas, the reserve’s design serves as open space for recreation and helps to manage stormwater.
The project team engaged extensively with local Maori communities for the design of the retaining walls which is based on hinaki, or Maori eel-catching baskets, to help conceal the major stormwater pond outlet structures needed for the new stormwater system.
As experts in timber crib retaining wall systems, Coffey was engaged to undertake the detailed design work of the complex shapes envisaged by the designer.
Coffey worked closely with landscape architect Isthmus Group to produce the detailed design of approximately 400 linear metres of curved timber crib retaining walls for the pond areas of the reserve. In addition to the detailed wall design, certification and construction monitoring, Coffey also oversaw all of the earthworks observation and testing associated with the re-contouring of this large 22 hectare development area.
A conventional sustainable system for an unconventional outcome
As the future commercial viability of the planned town centre was at least partly dependent on the success of the initial stages of the landscape development, the client insisted on using an expert design / build team.
Coffey undertook the retaining wall design using the landscape architect’s preferred sustainable locally produced ground retention product Permacrib to deliver the project.
The walls were technically complex because they involved some unconventional aspects of gravity wall design. The walls themselves were up to 5.5 metres high and consisted of ground supporting walls up to about 4 m high topped by architectural upstands, some of which were angled and others that were vertical and extended up to 2 metres above ground.
These upstands produced structurally eccentric loading on the walls, and created tall slender sections above ground that were prone to earthquake risk. The upstands therefore had to be tied down using nailed stainless steel straps to help ensure earthquake safety, and some of the more tightly curved upstands also had to be internally supported with plywood, without the use of any crushed rock infill, to maintain their individual stability.
During the project the team resolved various technical difficulties (some foreseen and others not), and made a number of pragmatic modifications to the original system to overcome the inevitable hurdles of using such an off the shelf product to achieve the client’s bold and ambitious vision.
An award winning outcome
The value to our client has been two fold; first, their vision has been realised with the delivery of an attractive, culturally sensitive, show piece reserve area at a reasonable cost, and second as a bonus the project has been recognised as the best landscape project by WAF, the world’s largest architectural awards program - which this year attracted 343 shortlisted projects from 58 countries across 32 categories.
Kopupaka Reserve photos courtesy of Isthmus & David St George Photography.