Pinto Valley Raptor-CPT

In 2023, Gregg was hired to investigate the full depth of one of the tailings storage facilities (TSF) at the Pinto Valley mine in Arizona. Pinto Valley is the largest upstream construction tailings dam in North America. No investigation had fully characterized the tailings down to native soil as surface efforts only achieved approx. 100m in depth. Gregg utilized the Raptor-CPT wireline method with a drill rig after pushing to 102m from the surface via a cone truck to achieve 175m in the deepest location.


  • Raptor-CPT used a memocone to collect data and store it on the cone without the need for cables
  • Reduced stroke due to “blind push” using information from drill rig hydraulics only


  • Reached native soil at 175m, the deepest on-land push!
  • Converted borehole to 8-level piezometer installation for economy of scale

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