Mammoet has completed a rapid headframe replacement at BHP’s Jansen potash project in Saskatchewan, using modular construction and self-propelled transporters to exchange a critical shaft structure without letting site complexity swallow the schedule.
The job centred on removing the lower section of an existing headframe and installing a far larger replacement to lift future mining capacity. Mammoet said the old unit weighed 796 tonnes, while the new headframe section came in at 2,090 tonnes and had to be manoeuvred into a tight footprint that also required docking into a staircase tower building. Before that installation, the company also handled the lift of a 60-tonne staircase tower module inside the structure using strand jacks, cranes, and a custom winch arrangement.
Most of the new steelwork was prefabricated in Alberta and transported to site in sections, an approach that reduced site labour and let fabrication run in parallel with preparatory works. At Jansen, however, the ground conditions were no small detail. Mammoet carried out route testing with SPMTs and counterweights, then mobilised more than 400 crane mats after identifying soft ground between the laydown area and the shaft. Additional shoring was installed at basement level near the shaft opening so the new structure could be set down without overloading the works below.
“We had to find a trailer configuration where we could carry the additional weight, be under the permissible ground-bearing pressure, plus be short enough to not clash with the existing structure,” said Mike de Wilde, Project Manager at Mammoet. That constraint drove the final transport set-up: double SPMT trains configured for both load capacity and geometry, then aligned to guidance lasers so the headframe could be lowered onto its engineered bolt pattern with almost no room for drift.
The replacement work lands as BHP pushes Jansen toward first production in mid-2027. Once Stage 2 is ramped up, the mine is expected to reach roughly 8.5 million tonnes of potash a year, making construction decisions around shaft infrastructure, materials handling, and modular execution more than just an exercise in heavy lifting.
