Nutrien Allan Potash Shaft Concrete Liner Remediation


David Murray, Nutrien Allan Potash

In 2017 Nutrien Allan Potash remediated a portion of the concrete liner in the production shaft.  A set of underslung work platforms and collection boxes were used in conjunction with hydraulic splitters, jack legs and hand chippers to excavate and remove the broken concrete.  New concrete was placed in kind per the original pressure relief design, using a shaft slip form.  It was found shortly after excavating, that the estimated breaking rate and amount of original concrete in-situ was under estimated.  The completion of 15 feet of excavated concrete and 10ft of replaced new concrete occurred on April 28, 2017 and the production shaft was turned over to mine operations. Starting in February 2019 Allan Potash has started to remediate a portion of the concrete liner in the service shaft.  The project is different compared to the 2017 project, as the remediation will occur during normal running operations and will occur only on nightshift.  Rather than hydraulic splitters and hand chippers, the contractor’s methodology includes a concrete saw and mechanical excavator off a working platform.  The selected methodology was based upon the lesson learned from the 2017 project in the production shaft.  The service shaft project is scheduled to complete in July 2019.  This will be a PowerPoint presentation, highlighting the design and methodology of remediation, comparing the two projects in separate shafts.