PotashCorp Allan Production Shaft Concrete Liner Remediation


Mr David Murray (Chief Mine Engineer - PotashCorp)

In November 2016, PCS announced a repair of the Allan Mine production shaft concrete liner. The concrete has deteriorated to a point where the liner was becoming a safety risk to the mine. In February 2017, a contractor mobilized on site, with a scope of work to remove and replace 60ft of concrete liner. This was the first undertaking of this nature in a potash production shaft in the province. This project was different than past occurrences due to the skips and shaft infrastructure remaining in place during construction. 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 estimated incorrectly. 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. This will be a PowerPoint presentation only highlighting the design and methodology of remediation with lessons learned.