Snowy 2.0 tunnel boring machine remains stuck after a month

Snowy Hydro released an update regarding the state of its 2,000-ton, 134m-long tunnel boring machine (TMB), which has been stuck in hard rock for a month.

Furthermore, it was originally announced on May 15 that the TBM, named Florence, had been slowing due to very hard and abrasive rock conditions, and was officially declared stuck on May 16.

Specialist contractors commenced on May 21, trying to remove the machine from the rock with high pressure water jetting.

A previous update, provided on May 30 by senior project manager, Guy Boardman, stated that the TBM was turned too sharply into hard rock, partly contributing to the event.

The update did not specify when Florence is expected to start drilling again, but it did mention that highly variable ground conditions are expected to continue ahead of the TBM.

It is worth noting that the TBM was stuck for eight months, starting December 2022, after it got stuck in soft soil just 70m into its drive, and caused a 9m depression on the ground surface.

According to some analysts, each day of delay in the project comes at a cost of $3 million. Direct costs due to TBM Florence getting stuck are so far estimated to be about $150 million, while indirect budget overruns could be much higher.

Florence has so far excavated 850 meters of Snowy 2.0’s 17km headrace tunnel, and the project’s delivery has already been pushed back to 2029 from the original early 2020s estimate.