Last year, WSP was commissioned by Tauranga City Council to design a seawall running 180 metres from Fisherman’s Wharf to the harbour’s Tidal Steps.
The new seawall is part of a Council initiative to rejuvenate the waterfront and reconnect people with the marine environment. What better way to do so than installing living seawall pods where tidal marine life can survive and thrive arms-length from passersby.
WSP coastal team leader Tom Wilde says when coastal defences such as new seawalls are created, natural foreshores and marine ecosystems are usually destroyed. By providing a home for tidal sea life, incorporating living seawall pods in seawall design is intended to help limit ecological damage.
WSP engineers completed the coastal engineering design of the rock revetment and worked closely with the client to identify a viable, local source of heavy quarried rock - known as armour stone.
All up, 100 living pod units were craned into position. They sit snugly among two thick layers of armour stone. Because the units weigh more than the individual armour stones, they could be used instead of armour stone in areas of the seawall with gentler gradients.
The yet-to-be-completed project landscape design features a wide footpath with planting and concrete stairs set into the seawall. It’s here that the public will have the opportunity to get up close to the living pods. Featuring deep, curved voids, the pods retain water as the tide goes out.
Specifying the pod units in the seawall blueprints was one thing; getting them manufactured and brought to site was another altogether. After canvassing options, WSP’s design and engineering team recommended Living Seawall Boulder units developed by Australia’s Reef Design Lab and the Sydney Institute of Marine Science.
Tom says WSP is proud to have contributed to the development of a procurement pathway for the innovative pods. Using custom molds manufactured in Australia, the units were cast in New Zealand.
The new seawall and living pod units sit a stone's throw from WSP’s Tauranga office. Tom has been down there several times and says marine growth is already starting to cling on.
Since being installed, scientists from the Regional Council and Toi Ohomai Institute of Technology have been down to check on marine colonisation in the innovative units. They’ll be running a long-term programme of ecological monitoring of the units.
Tom says few design, engineering, and build projects have used Living Seawall Boulder units before. They’re ideal for use in low energy wave environments such as Tauranga Harbour.
"It's brilliant to see a local project, designed by WSP, contributing to what is an emerging field of coastal engineering research.
“To take these products all the way through from procurement to install in what we understand is a New Zealand first feels amazing. There were lessons learned in how we showed the units in the design drawings, and how we can make them as easy as possible for contractors to install.
“The entire experience has been invaluable. WSP's coastal engineers have an in-depth understanding of how to integrate these pod products into standard seawall designs and construction and are keen to apply this to future projects.”
