Days Bay wharf in Lower Hutt is getting a $3 million upgrade but will remain open for use by the East by West Ferry.
The work is part of a bigger project to refurbish or demolish four Lower Hutt wharves.
Contractor Brian Perry Civil is required to keep the wharf open for Wellington commuters and to cause as little disruption as possible.
The East by West Ferry should not be disrupted by a $3 million upgrade about to start on the Days Bay wharf.
Council strategic advisor Bruce Hodgins said the wharf was in poor shape and the project would take 12 months.
Some piles need extensive repairs, while the decking also needs significant work.
Wellesley School old boy Marc Ellis (centre) and Principal Warren Owen (to his right) jump off the Days Bay wharf to celebrate the school's centenary year. The wharf has always been popular with jumpers.
Two of the council's other wharves, Petone and Pt Howard, sit on top of the aquifer that supplies much of Wellington's water, which makes repairing or removing piles difficult.
That is not an issue with Days Bay but the contractor will try and keep as many of the original piles as possibles.
The council looked at moving the ferry elsewhere, including to the Seaview Marina, but there was no where suitable, Hodgins said.
The Days Bay wharf was temporarily closed following the November 2016 earthquake.
Buses were also considered as a replacement for Wellington commuters.
The narrow section of the wharf, which leads to the large deck, will be closed. To provide access to the ferry, a cantilevered walkway will be added to the northern side.
Hodgins said although the contract was for $3m it was a difficult marine environment and the price could rise.
"We have a very large contingency built into it."
Brian Perry Civil contracts manager Chris Hodder said engineers were still working on the design of the cantilevered walkway.
He was confident that it would work and that there would be no disruption to ferry services.
In 2017, the council budgeted $7.3 million to repair four wharves, including Days Bay. The cost for the work has subsequently sky rocketed.
Rona Bay was recently refurbished for $3.3m. Work on Petone wharf has been delayed until 2031, with an estimated budget of $8m.
The council also plans to demolish the Pt Howard Wharf.
DAYS BAY WHARF
* Built in 1895 by JH Williams to provide access for passengers catching a ferry to Wellington.
* Ferries to Wellington began operating from 1893, with the Eastbourne Borough Council running the service from 1913 to 1948.
* The most well known ferry was the SS Cobar, which could carry up to 765 passengers. It ran from 1906 to 1948.
* The biggest ferry was the SS Duchess which carried 1029 passengers but was taken out of service in the 1920s after the introduction of buses to Wellington.