The cost of repairing a slip at Turnbulls Bay, beyond Broad Bay on Otago Peninsula, has jumped to more than $2 million after the project slipped months behind schedule, it has been confirmed.
The work, which began in January, had been expected to be completed by May, at a cost of $1.51 million, but was now not expected to be finished until September.
Dunedin City Council infrastructure and networks general manager Ruth Stokes said cost had also escalated along with the timeline, and now stood at ''in excess of $2 million''.
Exact figures were not yet known, but the bill was expected to be well below $3 million and able to be covered from existing budgets, she said.
The blowout came after contractors working for the council struck unfavourable ground conditions earlier this year.
That meant they had to dig deeper while searching for bedrock to anchor the foundations of a new retaining wall.
Council staff had initially hoped to complete the work on time, albeit at additional cost, but the size of the project had continued to grow since March, Mrs Stokes said.
As a result, the amount of material excavated from the site had increased by 56%, from 2300cu m to 3600cu m, while the overall work involved in the project jumped ''almost 70%'', she said.
Mrs Stokes said she had questioned whether the problems revealed a lack of geotechnical investigation, but ''it was one of those projects you did really just have to start to really understand what conditions were that you were dealing with''.
''We could have thrown a few more hundred thousand dollars at it [geotechnical investigations], or we could have just started the work. Obviously, the call was made to start the work and spend the money on what was required.
''You essentially had to dig up what we've dug up to find out what you were dealing with.''
The project was now about 75% complete, with excavations finished and work on the retaining wall weeks away from also being finished, she said.
That would allow reinstatement of the road, putting an end to a temporary traffic diversion, although the project would not be completed until the end of September, Mrs Stokes said.
The slip occurred when a storm undermined a section of Portobello Rd at Turnbulls Bay in mid-2013.
Repairs finally began in January, but struck trouble when a 15m-long crack along the road opened up at the site on February 24.
Council staff had tried to keep residents up to date on the project's progress since then, and allay any concerns the torrential downpour that caused flooding in Dunedin earlier this month could have further destabilised the site.
''The rain didn't actually affect it,'' Mrs Stokes said.
She was not aware of any complaints from businesses along the Peninsula, but thanked them and residents for being ''really understanding''.
