Date
Client
Location
Tectonic’s Role
Services Provided
- Detailed Geotechnical Investigations
- Inclinometer Monitoring
- Groundwater Monitoring
- Slope Stability Analyses
- Conceptual Remediation Options
Background
The Black Mountain Road landslide represents a significant geotechnical challenge in the SEQ Region, severely impacting the local road managed by Noosa Council. Following the February 2022 extreme rainfall event, approximately 150 m of road was closed due to significant failure of the road surface and safety concerns for road users and residents. Tectonic was initially engaged to complete a preliminary assessment and short-term risk management plan to enable nearby residents to return safely back to their homes.
Scope
To enable design of the road stabilisation, Tectonic scoped and completed a detailed geotechnical investigation including numerous test pits, boreholes and seismic survey lines, along with installation and monitoring of inclinometers and groundwater loggers. Results of the investigation and stability analyses concluded there were several modes of movement as part of a complex landslide ranging up to about 15 m deep. A multi-disciplinary and comprehensive remediation design was required to stabilise and reinstate the road.
Challenges
Geological conditions consisted of a basaltic cap overlying heavily metamorphosed phyllite, with recent and historic colluvium deposits. Complex groundwater conditions, surface springs and variable steep terrain made access across the site very difficult, with a combination of drilling and excavation methods utilised to successfully complete the investigation. The
