Rockfall hazard assessments and remediation for the major cliff precincts of Brisbane

Howard Smith Wharves (HSW) and Kangaroo Point (KP) are major cliff areas within the Brisbane CBD. The cliffs are former quarries for the supply of Brisbane Tuff rock and areas for essential industries of Brisbane. The cliffs have had a history of instability, resulting in rockfalls of varying significance. Over time, the usage of these spaces has changed, necessitating a structured monitoring and maintenance strategy to manage rockfall risks. Despite previous remediation efforts, residual risks remain due to the geological characteristics, historical quarrying, and evolving site usage.

For HSW, a risk assessment was conducted in 2021 in accordance with the Landslide Risk Management Guidelines (AGS, Volume 42, No.1, 2007) to evaluate rockfall risks impacting the main entertainment areas. The risk assessment considered the potential hazards identified during site inspections and the digital survey data of slope profiles at multiple locations. The geotechnical risk assessment outlined the requirement for permanent remediation to achieve a tolerable risk.

For KP, extensive historical quarrying and high recreational usage, including rock climbing, have contributed to ongoing deterioration of the Brisbane Tuff cliffs, requiring regular inspection and maintenance to manage the rockfall risks.

The detailed design phase for the remediation required site-specific remediation solutions due to the cliff locations and site usage. Remediation works were undertaken in 2024. A variety of rockfall protection measures were designed and installed, including recessed rock dowels, spider mesh, draped mesh and secured mesh systems.