Construction crews are in the final phase of a complex project to replace deteriorated stormwater pipes to prevent future sinkholes in Scott Street, Shoalhaven Heads.
Following months of deep excavation, trenching, pipe installation and challenging soil and groundwater conditions, sinkhole remediation works are planned for completion by the end of October.
Carey McIntyre, Acting Director – City Services, said this will be welcome news for residents who have lived next door to a busy construction zone for much of the year.
“The project’s degree of difficulty revealed itself as work was underway, meaning Council needed to adopt new designs with an extended timeframe,” said Mr McIntyre.
“Experience tells us that fixing sinkholes can be a complex and lengthy process. We had hoped to have the job finished mid-year and we thank residents for their patience and perseverance,” he said.
“Once the final pipes are laid in the coming weeks, we’ll be able to resurface the street, reinstate fencing, turf and carry out landscape works so that Scott Street can return to normalcy.”
Impacted by heavy rains in early to mid-2022, sinkholes in Scott Street were mostly caused by water and sand seeping into stormwater pipe joints that had continued to shift and open due to changes to the groundwater table. Sand drawn into the pipes joints created voids in the ground above the pipes, and over time, these voids collapsed resulting in ‘sinks’ on the ground surface.
Council’s remediation works have included:
- Deep (5.5 metre) excavation below the surface.
- Excavation of sand and removal of old stormwater pipes.
- Installation of 28 stormwater pipes running 66 metres.
- Trench shoring (bracing the walls to prevent collapse) and sheet piling (interlocking sheet steel to create a continuous wall to keep soil back).
- Extensive pumping of ground water to remove water from inundating excavation site.
- Working around and in close proximity to underground public utilities and homes.
- Restricted work hours to minimise the impacts of noise and vibration.
