A further $4.5 million has been earmarked for installation of the new sewer main in the city's downtown.
City council approved the increase on Monday night, boosting the total cost of the project to $5.1 million.
The money will come out of a reserve for such projects and the tax levy will not be affected, council was told.
The pipe has been installed but work to switch over from the old sewer to the new sewer, and restoration and cleanup are still to be done this year.
In a report and presentation to city council, engineering projects supervisor Hayley Sedola said the original intention was to relocated 230 metres of a 30-centimetre trunk gravity sewer along the alleys from Sixth Avenue and across Queensway to Ontario Street.
But preliminary engineering work revealed limited room in the lane, conflicts with other utilities and insufficient pipe slope.
As well, adjacent development in the area - notably the Park House condominium project, the new Four Seasons Pool and a new hotel - meant additional capacity will be needed.
The plan was revised to install 1.1 kilometres of new line stretching east along Lower Patricia Boulevard from a lift station at Dominion Street and Seventh Avenue to one near Lower Patricia and Fourth Avenue. T
he intersection of Queensway and Patricia Boulevard was closed for most of November and the first week of December to install the line along Patricia.
The work hasn't been easy. Sedola described the existing piping along parts of the route as "a bit of a bowl of spaghetti" that has required workers to weave the new line through existing infrastructure.
Each of the pipes have had to be exposed by hand to make sure they're not damaged by heavy equipment, Sedola said, and added some of it is fragile due to its age, "so it can be delicate to work around."
Trouble with groundwater added to the challenge, Sedola said.
The jump in cost raised alarm bells for Coun. Brian Skakun.
In response, engineering and public works general manager Dave Dyer said costs are rising in general because contractors are so busy.
"We might have more difficulty getting contractors to bid and if they do, it'll be pricey," Dyer said.
Council was also given a preview of changes in store at Veterans Plaza in front of city hall that will be part of the work.
Cautioning that the plan is still in draft form and stakeholders are still being consulted, city engineering director Adam Homes said parking on the north side of Seventh is to be removed and the sidewalk widened providing room for trees and street lights.
A sidewalk is also to be added on the south side of Seventh while the plaza will be expanded north to towards Sixth Avenue.
A section of George Street, running along the northeast side of the plaza will be closed and a lighted walkway put in place connecting Seventh and Patricia.
Seventh Avenue would be used more as a plaza, Homes said, with temporary bollards at the entrance to Sixth Avenue and at the entrance to city hall so the stretch can be blocked off for events. There will also be plug-ins on the street lights for vendors to use.
The aim is to have Seventh open by the summer and the plaza area ready by late fall. As for work along George Street, that would likely occur next year with landscaping along Queensway the year after.
Council also voted to use the city's endowment reserve as the source for the $12.6 million budgeted for the parkade to be constructed as part of the condominium project.