Port Otago Oil Wharf strengthening

An increase in the size of the ships using the oil wharf at Port Otago meant additional strengthening was critical for the long-term survival of the 1960s-era wharf. Our project involved installing new dolphins adjacent the existing wharf, then bracing from the dolphins to the wharf.

Naylor Love secured the project with an innovative methodology that de-risked the project operationally, as we carried out the work from the shore rather than off the wharf. Our alternative involved prefabricating the majority of the dolphins offsite and installing them in sections in cofferdams.

We used a 400t crawler crane to place temporary sheet piling into the seabed, forming the cofferdams that allowed us to the pour concrete foundations to anchor the huge prefabricated metal dolphins, which were also craned in. Quality control was critical, as the engineer needed to be confident the new dolphins could handle the forces of heavily laden tankers pushing against them while berthing and in high winds.

Working over water with large machinery into 12-metre-tall cofferdams and around fuel lines in a fully operational, high-security wharf required meticulous daily planning and coordination with the port authority. The project was completed with an excellent safety record and is estimated to have extended the life of the wharf by another 25 years.