The 1960s-built wharf hosts about 32 tankers each year, mainly from the Marsden Point refinery carrying petroleum products. The tankers invariably bump and grind against the 215m wharf, which has wooden piles and concrete decks.
A crane is at present placing temporary sheetpiling into the seabed, which when completed will be excavated, leaving a 12m hole to the sea floor; at low tide.
A 20cu m concrete foundation, 10m by 2m by 1m deep, will then be poured into the excavated seabed to anchor metal berthing frames, which are attached to strengthen the wharf.
Port Otago general manager of infrastructure Lincoln Coe said that once the foundation was completed, the sheet-piling would be removed and used for the next foundation. There would be little physical change in the wharf's appearance.
Generally, the wharf is used to discharge bitumen, petrol, diesel, aviation fuel, heavy fuel oil for marine vessels, light fuel oil, marine diesel and bitumen, with vessels connected to fixed shoreside pipelines using a single flexible pipeline.
Port Otago is not installing a New Zealand-made magnetic berthing system now used in several ports around the world, mainly for ferries; but a traditional rubber fender system between the tanker and wharf to cushion the loading.
The contractors arrived on site last month, with the crane expected to be there a further three or four months.
The project is expected to be completed by October.
While tankers most often use the oil wharf, for the first time in 35 years last month a log ship berthed alongside because of increased log demands. In August, a navigational beacon was clipped and damaged during the departure of the fishing vessel Oyang 77 from Leith wharf.
