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Deep CPTs to Characterize Mine Tailings at Pinto Valley

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The Pinto Valley mine in Arizona utilizes upstream construction to contain tailings consisting of predominately sand and silt to a maximum height of about 172 meters (m). Characterization of the in-situ tailings to full depth is key to understanding the overall behaviour of the facility. Previous investigations of the tailings from the dam crest using conventional surface core penetration testing (CPT) to a maximum depth of around 100 m or less was limited due to the dense upper sand tailings combined with accumulated push-rod friction. To fully characterize the complete tailings profile, an innovative technique was used incorporating a combination of conventional truck-mounted surface CPT pushed to refusal, followed by a rotary drill rig using incremental wireline CPT (Raptor-CPT) to greater depths. This paper describes the incremental drilling and Raptor-CPT method that was able to achieve a final depth of 172 m, possibly the deepest onland CPT on record. Specifically, the wireline method allowed for rapid deployment of the cone down-hole without the need for push rods from the surface as the cone is latched into the bottom of the drill string. Additional benefits and testing on site included seismic measurements and the ability to take samples of the tailings for further laboratory testing. The wireline CPT borehole served a dual purpose by installing an 8- level nested set of vibrating wire piezometers for on-going monitoring.

Text

2023-12-08

Attribution-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86782

Unreviewed

http://creativecommons.org/licenses/by-nd/4.0/