Auckland's $73m seawall strengthening finished ahead of deadline, under budget

Seawall strengthening met its completion target. Photo / Supplied

Auckland's 600m-long Quay St seawall strengthening project was completed a fortnight ago, beating its projected deadline and coming in up to $2 million under budget.

Eric van Essen, Auckland Transport's downtown programme director, said today the Ferry Basin seawall project had met the completion target in mid-January. The job was due to finish in either January or February so it was done early.

SEAWALL

"My understanding is that we're coming in under budget as well," he said. Final costs are yet to be confirmed but a $1m to $2m saving on the original $75m budget is anticipated.

But disruption continues in the area where it was once hoped work would be finished in time to showcase the city during the America's Cup.

The seawall forms the harbour edge of an historic land reclamation that supports Quay St and the services under the road corridor. The first sections of the reclamation were built between 1875 to 1886 along what is now Quay St west of Britomart, and also east of Britomart parallel to Beach Rd.

Subsequent sections were added after the turn of the 20th Century.

The seawall and Quay St upgrade projects have continued to narrow the busy east-west waterfront thoroughfare. Businesses and politicians have complained about it since work started three years ago.

But he acknowledged the wider work to upgrade the downtown end of Quay St was continuing.

Seawall strengthening met its completion target. Photo / Supplied

"Obviously in 2020 everyone can appreciate that with Covid, there were delays to work but the contractors have done a remarkable job winning back time. We are now 85 per cent complete across the wider programmes which is six separate projects including the seawall and the Quay St upgrade," van Essen said.

The six projects are the seawall, Galway St enhancement, Lower Albert St bus interchange, Te Wānanga [tidal shelf over water for people to gather], ferry basin redevelopment with six new berths on the west side of Queen's Wharf and the Quay St enhancement which squeezes it from four lanes down to two at one point.

"We were due to finish all six projects for the American's Cup under the original plan which was to have all major works complete by 2020 with minor works complete by early 2021. But the revised programme is to have all works finished in the area by the end of April and minor works finished by May or June," van Essen said.

The seawall completion was a milestone and a major step forward in finishing work in the area.

"The seawall is an incredible achievement given the fact it's been a long time in the planning and to have significant investment completed. It strengthens Quay St for the next 100 years," he said.

Quay St, between Commerce and Albert Sts, will be narrowed to two traffic lanes, one in each direction. That is allowing much wider new footpaths for dining and higher pedestrian flows as well as new street furniture, planting and landscaping to provide a more people-friendly waterfront environment.

"It is quite a unique juncture between ferries, rail and buses, all within 100m of one another so you've got a busy confluence of movement and that's where we need to provide additional space for people," he said.

"Having that additional footpath space is vitally important," van Essen said.

Pile driving on the $75m project to hold the sea back from the CBD. Photo / Supplied

Completion of jet grout piling in the Princes Wharf to Ferry Basin section of the seawall was a major benchmark in the programme and that part of the job was finished last winter.

The strengthening, in four sections, starting mid-2019 involved:

• Princes Wharf to Ferry Basin: jet grout column construction complete, all 153 jet grout columns done.

• Queens Wharf to Marsden Wharf: palisade piling construction, all 104 new palisade piles in place;

• Ferry Basin: incline anchor construction started mid-2019, finished late last year with 29  inclined anchors;

• Ferry Building: incline anchor construction when 21 sub-vertical incline anchors were installed west of the Ferry Building through the existing seawall.

Van Essen said the project was crucial in an area which was expanding fast, with the $1b Commercial Bay and the $1b-plus Britomart redevelopment and restoration.

The existing wall was between 100 and 140 years old in some sections and protected Quay St and the services that run beneath it.

He expects it will now future-proofing the CBD for the next 100 years. Without the seawall, large parts of downtown Auckland would be under water, he said.

Engineers designed the project for a one-in-2500-year event or a 6.5 magnitude earthquake. It also allowed for a sea-level rise up to 1m during 100 years and was in line with climate change guidelines and predictions, he said.

Since an initial assessment in 2012, urgent work was finished. Divers have carried out annual monitoring to ensure nothing more urgent needed attention until the work started, van Essen said.