Client
BG&E, CMC, Richmond Valley Council
Location
Naughtons Gap, NSW
Sector
Infrastructure & Transport
Services Delivered
Construction Phase ServicesGeotechnical Site Investigation and CharacterisationLandslip Remediation DesignSlope stability assessment
The challenge.
Naughton’s Gap Road is a critical regional transport link in NSW’s Northern Rivers that was closed for more than three years following major landslip damage caused by successive extreme rainfall events. The site presented complex and variable failure mechanisms, including deep-seated and rotational landslides within colluvium and embankment fill, compounded by high groundwater levels. Richmond Valley Council required a resilient, funding-eligible remediation solution that could be delivered safely, quickly and with long-term performance in mind, while restoring connectivity for the local community.
The approach.
FSG worked collaboratively with CMC and BG&E from concept design through construction, providing specialist geotechnical insight to understand landslide mechanisms and inform a targeted stabilisation strategy. Comprehensive investigations and monitoring enabled the design to respond to multiple failure mechanisms across the site. FSG’s experience and engineering judgement supported the development of a hybrid solution centred on a rock socketed bored pile wall system combined with earthworks and upslope drainage measures and adaptive staging that progressively improved site stability. During construction, FSG maintained an active site presence, including inspection and verification of pile founding conditions and implementation of a slope monitoring management plan linking rainfall, groundwater and movement response.
The outcome.
The project successfully reopened Naughton’s Gap Road in December 2024—three months ahead of schedule and under budget—restoring a vital transport connection for the Northern Rivers community. Despite record rainfall during construction, no further landslips occurred, validating the temporary and permanent geotechnical design approach. FSG’s involvement contributed to a safer, more resilient road with an improved 100-year design life and strong confidence from Council and Transport for NSW in the long-term performance of the remediation works. The project is recognised as a benchmark NSW disaster recovery outcome and demonstrates FSG’s capability in complex, high-risk slope stabilisation projects.