Emergency services were called to the intersection of Bank St and Vine St at 11.10am after a customer at the Co-operative Bank complained to staff about the smell of gas outside the building.
The Co-operative Bank employee immediately phoned emergency services to report the stench.
A cordon was put in place around the scene and traffic directed away from the roads while the firefighters and Gas First worker checked the sidewalk manholes and other areas with gas detection equipment to determine if any substances were present that would indicate a suspected leak.
In less than an hour the sewer was identified as the source of the gas smell, which was not uncommon, and Vine St was reopened just before 12pm.
Ballantine was pleased the public were proactive at reporting suspected gas leaks.
"We definitely encourage this type of behaviour - it's commendable," Ballantine said.