An extraordinary council meeting will be held tonight (Monday) to approve funding without a tender for emergency stormwater works on Captain cook Drive, Woolooware.
A report by Sutherland Shire Council staff says the works need to be carried out urgently to mitigate flood risk.
Problems were discovered by a contractor working for Capital Bluestone on reconstructing and realigning the intersection of Captain Cook drive and Woolooware Road, as part of the Woolooware Bay Town Centre project.
The contractor discovered a chamber, or pit, in the existing council stormwater system, built many years earlier, was not functioning.
Upon excavation, the chamber was found to be structurally unsound, buried beneath fill contaminated with asbestos and was full of sediment.
The report said the stormwater system in that area was tidally influenced and had progressively become blocked with sediment due to past poor design and construction standards.
The council had not been able to monitor the condition of much of the system due to a lack of access manhole lids.
The report said, to determine why the chamber was not functioning, the contractor had to excavate and break into the system.
The investigation found the pit and pipe system upstream and downstream of the chamber was also not functioning.
The report said it was "imperative" to complete maintenance and clearing works urgently to mitigate flood risk and to meet time frames in development contracts.