ABSTRACT
The Borumba Pumped Hydroelectric Energy Storage (PHES) project’s Exploratory Tunnels face challenges due to limited geotechnical information and ground subsurface uncer-tainties. To manage these challenges, Queensland Hydro (QH) adopted a flexible and collabora-tive contractual framework for tunnel procurement and delivery. The contract, based on the NEC4 Engineering and Construction Contract (ECC) with use of a Bill of Quantities (BoQ) to facilitate effective risk management and equitable allocation of geotechnical risks between the Client and Contractor. This paper outlines the integrated ground risk management process developed to sup-port the technical and contractual delivery of these tunnels, incorporating an observational ge-otechnical design approach.
