Calliope South Access Jetty - Major Remedial

The Calliope South Access Jetty is an important structure linking the Royal New Zealand Naval Base at Devonport, Auckland, to the main Callipe South Wharf. It is a seven span structure, with reinforced concrete piles and headstocks, prestressed precast concrete beams and a cast-in-situ reinforced concrete deck over. 

With the location of the structure in the Waitemata Harbour, the influence of tides and the nearby ferry wasj, the design of the scaffold platform was an important aspect of the project. While testing showed corrosion activity in other structural elements, the high risk and consequence of corrosion to the prestressed beams warranted these elements receiving urgent attention. Various diagnostic work led to the engagement of specialist consultant, GHD Pty Ltd, to undertake a Condition Assessment of the structure. This included visual inspection, delamination and covermeter survey, concrete resistivity, electrical continuity and stray current testing. This was aimed at providing information as to the suitability of impressed current cathodic protection system for long term protection. 

Given the congestion of strand in the beams, hydro-demolition was chosen in order to expose them for continuity testing and to provide continuity welding where required. This work was completed with no impact on the full operation of the structure. Approximately 7,000 lineal metres of Lida titanium anode were installed into a selection of concrete cuts and chases depending on the depth of cover to reinforcement. Progressive commissioning resulted in a smooth final commission and hand over.