Heavy showers and an unexpectedly complex "spaghetti city" of cables, pipes and drains have stalled Wollongong City Council's Crown Street Mall refurbishment works.
However, infrastructure and works director Mike Hyde said council staff and contractors were working to ensure this week's hiccups did not cause long-term delays to the project.
"One of the huge challenges here is that we're sitting on top of a spaghetti city," he said.
"You've got all the services underground - various types of communications, water, a sewer, the old traffic light system and stormwater drains that date back generations."
He said contractors had done underground mapping to find out the state of the services, but were still finding surprises as they stripped back dense layers of reinforced concrete.
"This has a big impact on making the project stay on time ... so we are facing challenges now to try and stay on schedule," Mr Hyde said.
Council site coordinator Warren Brown said rain had also hindered progress in the past few days.
"We had planned to have four more groups of tradesmen up here working," he said yesterday.
"They were going to be working on electrical systems, we were supposed to install lighting brackets and all of that has been cancelled, so that will impact the pavers who were supposed to come in as well."
Despite the numerous setbacks, Mr Hyde said the council still hoped to meet its planned October deadline.
"In most other projects, we'd just say we'll extend the time of the project and go over time but here we really want to achieve the October completion date - and that is to avoid going into another season that would impact the businesses," he said.
Replacement of the asbestos-ridden Telstra pits is due to begin on Monday, weather permitting, while installation of a new decorative lighting system will begin in about eight weeks.