The historic Ferry Terminal (harbourside) building was constructed in 1912. A reinforced concrete seawall beneath the terminal descends 8m deep and protects the building’s stability against significant backwash from the daily ferry services that operate out of the terminal.
A large scour in the seawall was detected in Oct 2016. By Aug 2017, a routine dive inspection of the 100-year-old wall revealed the hole had doubled in size (16m long, 3m high and depths of 1.2m). This discovery was alarming as 1.3m depth is the tipping point and poses a significant risk to the stability of the historic building.
The problem was acute, and the risks were high, calling for an innovative and urgent solution that would least affect the public, businesses in the ferry terminal and Fuller Ferry operations. A project team was assembled and all parties agreed on the LDE design solution to plate the wall with sheets of stainless steel, to be used as shuttering. A team of divers placed the sheets in situ, and the voids were then pumped full of grout. The seabed in front of the area is now protected by an Elco-rock sandbag.
This kind of in situ underwater repair to a seawall was unique in New Zealand. It required a careful, flexible approach and a customised design. Every aspect of the design and method had to be adaptable to last-minute changes.
Location: Downtown Auckland CBD
Client: Auckland Transport