Geotech slope instability assessment & mitigation

The Project

This is a project undertaken by PDP for a major energy supply infrastructure provider as part of their infrastructure assets and pipeline network operation and management in the North Island regions.

The Hazards

Geohazards to one of their pipelines were identified during their monitoring and maintenance regime. The instability features were located on the steep slopes adjacent to the pipeline. To mitigate risks of potential slope instability and erosion impacting on the land cover and support for the pipeline, several remediation options were proposed.  Evaluation was undertaken with the Client’s project and engineering teams to select the preferred engineering option for further design and construction. The remedial works selected for stabilising the steep slopes included removal of existing mature/die-off pine trees, removal of excess easement fill where required, and installation of soil nails with high tensile steel wire mesh and erosion control matting system. 

Our Involvement

Our PDP team was involved from the initial geohazard assessment and site investigation through to optioneering of remediation solutions, concept design and final detailed design.  We also provided technical support during the construction phase including contractors’ tender review, site monitoring and inspection of works and testing.  The remediation works was successfully completed in 2020.

Geotech slope img 2


Key Aspects
  • Slope stability remediation engineering solution 
  • Strong and continuous collaboration with the client over a long period of time
  • Completion of full project cycle with work phases comprising the initial geohazard assessment and site investigation through to optioneering and design, and construction support and completion.