"The slot drain was the first we've ever installed, so it was a little bit touch and go.
"The contactor made a mistake in the installation and has admitted they're at fault... As it's their mistake there's no cost to ratepayers."
Ms Mannion said a street celebration, driven by what businesses wanted, would mark completion of the works early next month.
The project has drawn a mixed response from businesses " with some complaining about a lack of parking and associated revenue loss, while others said it was good to see council investing in the retail area.
In response to concerns, the council was allowing one hour's free parking on Vine St or on the top level of the Central City Carpark, on the corner of John and Robert Sts.
Part of the pedestrian-friendly lane will be covered by two 13m-high canopies made of ethylene tetrafluoroethylene (ETFE), a transparent polymer which also covers the Forsyth Barr Stadium in Dunedin. Anybody with questions about the project could visit the site office on the corner of Quality and Cameron Sts, or phone the district council.
The council is also looking at banning smoking in the CBD.