2024 – Application of a Geotechnical Baseline Report in Dam Procurement and Construction

James Toose, Christopher Dann, Mark Lawrence

This paper provides a case study for the adaption of the principles of a Geotechnical Baseline Report (GBR) for use in the procurement and construction of the Upper Yarra Dam Safety Upgrade Project to address specific project risks and some of the common challenges in dam construction. The purpose of a GBR is to establish a framework for risk sharing and evaluation of latent conditions claims. The principle being that risks associated with subsurface conditions or other identified conditions consistent with, or less adverse than, the baseline conditions set out in this GBR are allocated to the Contractor. Conditions that occur that are more adverse than the baseline conditions are allocated to the Project Owner. The original embankment comprises of a zoned earth and rockfill dam with a central earthfill core with broad transition zones of “soft rock” upstream and downstream of the central core and outer rockfill shoulders. It has no distinct filter zones to protect against internal erosion and piping through the embankment. The upgrade was designed to address the risk of internal erosion and piping in the upper embankment. The paper describes the development process and inputs into the GBR, the types of risks and conditions included in the GBR framework and a discussion on the implementation and supporting documentation used through the delivery of the project. It concluded that the GBR was a useful communication tool to inform tenderers of site conditions and risks both during the tendering and construction phases.