The work includes the breaking-out of concrete in the joints on the top level, to replace existing coating with a flexible and waterproof jointing system, which the council says allows for joints to move without causing cracking as buildings heat and cool.
Most of the noise across the city was that of ultra-high pressure blasting to remove the concrete out of the joints before the new jointing system is added.
The same blaster is also being used to remove paint on the lower level before it can be repainted.
The building was opened in 2000, has 58 spaces on the covered ground level, with an average weekly occupancy of 62 per cent, and 63 on the uncovered top deck, popular for its $5 all-day parking and with average weekly occupancy of 86 per cent, the council says.
It says below 50 per cent would be under-utilisation, and over 85 per cent is considered over-utilisation.