NSW Office of Environment and Heritage (OEH)
Sydney Harbour National Park, Manly, NSW


Our involvement

Geotechnical assessment including an initial aerial drone survey, subsequent cliff-face inspections using abseil ropes and comparison of the current cliff face and viewing platforms compared with our report for the construction of the existing lookouts completed in 2000. JK Geotechnics completed an assessment of the risks associated with further cliff face collapse and their potential impacts on the very popular cliff-top lookouts.

Project challenges

OEH reported that a rock fall had impacted the southern cliff face of North Head. There were concerns regarding the stability of the three cliff-top lookouts and an informal fisherman’s ladder access to the base of the cliff. The cliff face was a maximum height of 75m and required a comprehensive abseil rope access system directed by abseil rope specialists (RATTS) to facilitate the geotechnical assessment.

Our solutions

JK Geotechnics completed risk assessments in accordance with the AGS 2007 methodology and analysed the potential cliff-face collapse which was controlled by open joint plans and undercut sections of the cliff face below the viewing platforms. Based on our advice, OEH closed a section of the Fairfax Lookout and closed the two remaining lookouts.