Managing slope instability in the Dandenongs and Yarra Ranges – Technical Presentation

Neville Rosengren and Darren Paul

This Technical Presentation is followed by a Field Trip on 1 April
(click here for more information)

Landslide risks in the foothills of the Dandenongs and the Yarra Ranges are well known to the local geotechnical engineering industry. Large periodic mobilisations of the thick residual volcanic soil and weathered rock profiles in the Older Volcanics and Devonian-aged rhyodacites can occur at relatively shallow slope angles. As the pressures of urbanisation push residential development onto these (and other) slopes, a greater awareness of slope stability issues is needed by regulators, land owners and geotechnical practitioners.

To promote the safe and sustainable development of hillside properties within the Yarra Ranges Shire, an erosion management overlay (EMO) has been developed to ensure that any new development can be designed to minimise risks from slope instability. The overlay has been incorporated into the local planning scheme, prompting both land owners and the regulator to implement appropriate hillside development practices.

On the Thursday evening, Neville Rosengren will describe the geological and geomorphic setting of the Dandenongs and Yarra Ranges. Joining Neville will be Darren Paul, who will discuss how the identification and mapping of historic landslides and potentially unstable slopes has been incorporated into the Yarra Ranges erosion management overlay. The overlay has been in place since 2001; Darren will provide his insight into how the overlay has changed development practices on these slopes, and what they mean to the practising geotechnical consultant.

Darren will lead the field trip on Saturday, discussing the geological and geomorphic significance of the known landslide sites. Landslide hazards and the means by which the risks associated with them will be discussed. The field trip in particular will provide an opportunity for our members to explore the engineering issues associated with the landslides in a growing municipality.

About our presenters

Neville Rosengren is a geomorphologist with 45 years of experience in research, teaching and consultancy in Australia and overseas. Over this time, he has been engaged as a consultant by State and Commonwealth Government agencies, major private sector environmental consulting firms and was senior environmental consultant to the United Nations University programme on coastal resources management in Indonesia.

Neville has been involved with the identification, protection and teaching at Sites of Geological and Geomorphic Significance since the 1970’s. He published studies of such sites around the greater Melbourne area. He has long had an active interest in the conservation of geological sites and has published major inventories of sites on a regional and thematic scale. Since relinquishing his position as Senior Lecturer in Earth Science (so he could live in New Zealand), he has remained active in consultancy and community coastal interpretation programmes in Victoria. Neville is now an Honorary Associate of La Trobe University and a member of the Science Panel of the Victorian Coastal Council.

Darren is a principal engineering geologist with Golder Associates, Melbourne office. He has provided consulting services related to landslides in the Yarra Ranges since the implementation of the EMO in 2001 and works with several other municipalities to assist them in managing slope related hazards. He is the immediate-past National Chair of the AGS, and co-developed the AGS Field Technique for Landslide Assessment course (details can be found at https://australiangeomechanics.org/course_post/field-technique-for-landslide-assessment/), which he presents alongside other engineering geologists Fred Baynes, Phil Flentje and Tony Miner.

Venue location

Engineers Australia members participating in AGS technical sessions can record attendance on their personal CPD logs. Members should refer to Engineers Australia CPD policy for details on CPD types, requirements and auditing guidelines.