Engineers Australia

Geotechnical Management of Large Scale Slope Deformations at the Teal Gold Project, WABest paper (young professional - high commendation) from the 13th ANZ Conference on Geomechanics, Perth 2019

James W. Watton and Mark J. Fowler

Abstract

This case study demonstrates the ability to successfully operate beyond conventional open pit slope performance criteria at the Teal open pit gold mine near Kalgoorlie, Western Australia. The majority of the east wall of the open pit deformed in a ductile manner as mining progressed to the target depth of 50m. Maximum total displacements were in the order of tens of meters and cracking was observed up to 90m behind the crest of the pit. Rates of wall displacement in excess of 10mm per hour were experienced during mining. The slope deformations experienced at the Teal open pit were success- fully managed as a result of highly responsive geotechnical slope design and management. Design modifications included partial unloading and changes to excavation sequencing to limit deformations and to prevent ore sterilisation. Slope management comprised of prism and slope stability radar monitoring, a carefully developed trigger action response plan (TARP) and equally importantly, proactive mining operations. The application of slope stability radar monitoring allowed the operational management of slope deformations in excess of historically achievable rates. The pit was successfully completed at the planned metal grades, with a 5% surplus in ore mined.