Customer: Port Nelson Ltd Contract: Design & Construct Location: Nelson, New Zealand

Fast Facts Deconstruction of existing 100 m section of operational wharf Removal of 148 x 100-year-old timber piles 18,5000 m3 of seabed dredged 100 m long x 17 m deep driven sheet pile retaining wall 4,000 m3 of ground improvements 12m deep 48 x 762 mm diameter tubular piles The placement of 7,000 t of rock underlayer and armour Construction of new wharf deck and adjacent land slabs requiring 2,340 m3 of concrete and 907 t of reinforcing steel Eight 50 t fender support panels were pre-cast on site Installation of pre-cast fender support panels under the deck edge and post-tensioning of anchor bolts Installation of Trelleborg fender units and mooring bollard hardware Denso Seashield corrosion protection system for wharf support piles Installation of Cathodic protection for wharf deck reinforcement and steel piles Sprayed concrete cladding to sheet pile retaining wall Installation of two 300 m2 grout mattress protection

We demolished a 100-year-old wharf and designed and constructed a 100 m-long replacement for Port Nelson Ltd, without impacting their operations. The new wharf caters to larger container and cruise vessels and is also more resilient to seismic activity.

We commenced with the demolition and removal of the old timber and concrete structure, together with its associated fendering, concrete retaining wall, and two piled bollards.

The 100m wharf replacement and associated works at Main Wharf North needed to be constructed without impacting the shipping operations and the ability of container vessels to continue to moor alongside the Main Wharf.  A methodology was developed by the team to minimise the interface between construction activities and Port operations in the confined site area.

We scheduled work around ship movements wherever possible. A detailed program of parallel activities was established to manage work in the confined construction area so wharf operations weren’t impacted. We also used local resources, which provided more flexibility when the timing of critical activities was affected by unplanned shipping movements.

Another major challenge was working over water while minimising disturbance to marine life and working around the 4m tidal.

Shotcrete was applied to the face of the sheet pile retaining wall in place of in-situ concrete to eliminate the need for temporary formwork in inter-tidal zones. Equipment was also adapted for the marine environment, using floatation devices to minimise the need for lifting operations under the completed deck. These innovations helped protect the marine environment, ensured consent conditions were met, and made completing the work much easier.

Our experienced team, detailed programming, good communication, and close collaboration with the Port Nelson team, ensured the delivery of a high-quality infrastructure asset that will help unlock the region’s future growth.