Rockfill Quarry Experience, Ord River, Australia

The main feature of the Ord River Project in Australia is a rockfill dam constructed by Dravo Corporation. Quartzite rock was quarried adjacent to the damsite using “coyote” blasting methods and involving the largest explosion detonated to date on the Australian continent. The blast vibrations closely approximated predictions and caused no damage although in close proximity to a number of faults and to the recently grouted foundation and a concrete intake tower then under construction. However, the quarry rock proved to be unexpectedly difficult to blast, excavate, and handle, demonstrating the need for more thorough prebid studies of rock characteristics on projects of this magnitude and complexity.