In 2022, severe weather events along the east coast of New South Wales resulted in widespread slope instability. Prolonged and intense rainfall, with the primary event commencing in June 2022, triggered multiple landslips within the Cessnock City Council area. These landslips caused significant damage to several sections of roadway, impacting safety and access.
The project involved the remediation of three separate landslip sites along Great North Road near Buckety. The works required geotechnical assessment, constructible remediation designs, and optimisation of materials to ensure safe, efficient, and durable slope stabilisation solutions.
Witt Consulting was engaged to provide geotechnical engineering services in support of AnewX, who were contracted to design and construct the remediation works.
Scope of Services
Witt Consulting provided the following services across the three landslip sites:
-
Slope stability assessments
-
Design of working platforms and access ramps
-
Landslip remediation design for two sites
-
Staging, constructability advice, and design optimisation for a third site
-
Geotechnical site inspections during construction
-
Material testing to support design assumptions
All design services were delivered directly to AnewX to support the design-and-construct delivery model.
A key component of the project was the reuse of ripped sandstone as engineered fill within the remediation works. To validate and optimise the design parameters, Witt Consulting conducted advanced laboratory testing using in-house large-scale triaxial testing equipment.
The triaxial cell used was 300 mm in diameter and 600 mm in height, allowing the inclusion of particles up to 63 mm in size. This provided a more representative assessment of in-situ material behaviour compared to standard laboratory testing, resulting in more realistic and higher shear strength parameters.
Outcomes
-
Optimised landslip remediation designs with improved constructability
-
Validation of reused fill material, reducing the need for imported materials
-
Efficient staging and construction sequencing to minimise disruption
-
Robust, fit-for-purpose remediation solutions addressing long-term slope stability
By combining advanced laboratory testing, practical design optimisation, and close collaboration with the contractor, Witt Consulting delivered efficient and constructible landslip remediation solutions. The use of large-scale triaxial testing enabled confident reuse of site-won materials, improving both sustainability and project value while maintaining safety and performance.
