Byrnecut Australia - Prominent Hill Shaft

What we did 

• Sinking stage proof engineering for a 6 story, approximately 36m tall, 7.5m diameter sinking stage. Proof Engineering tasks included the structural verification, mechanical systems and lifting equipment.  
• Topside structural engineering for a number of assets associated with the sinking stage at the Prominent hill site. These included winder slabs, winder foundations, winders sheds and cable reeler foundations.
• Topsides proof engineering of the Brace and Sub-brace that close the shaft at surface level. The Sub-Brace was subject to numerous challenging load cases as it functioned as a temporary suspension platform for the stage during installation.   
• Electrical engineering support documenting the capacity to Byrnecut on an as needed basis to support their design and installation program. The increased resourcing facilitate by pitt&sherry assisted Byrnecut to maintain program during critical periods of effort.
• Mechanical engineering design input, proof engineering and regulatory submission management for the sinking stage. 
• Crane and Lifting equipment Proof Engineering of multiple structural investigations and provided test and commissioning guidance for the lifting points located throughout the sinking stage. We have subsequently assessed rating increases on lifting points to facilitate operational requirements. As the sinking operation progressed, some design cases were found to be inadequate. Our support of the rating increases has improved production efficiency on site.
• Engineered Lift – Stage Installation: A highlight of our mechanical engineering involvement in the Prominent hill sinking stage was the engineered lift of the ~78T stage. This involved the sequenced lift of each component, it’s suspension above adjacent sections for connection and finally its installation into the shaft. The lift consisted of a 4 point engineered lift utilising the site crane and engineering assessment of the joining sequences. The lift, connections and installation were all undertaken without incident and on schedule.
• Permanent Liner Design – Interface: The Prominent Hill winder shaft comprises a VSM bore with pre-cast segmented liner to 90m and a cast in situ liner below. We designed and engineered the interface between these two discrete liner systems with a permanent liner solution. This liner was required to accommodate the loads from not only the ground pressure, but any differential loads impacted by the two alternative systems above and below. pitt&sherry undertook this design under stringent time constraints to support the construction program and delivered solutions that met the client’s brief.

Outcomes

Construction is currently on target. Byrnecut and pitt&sherry are working collaboratively to solve problems on the go with additional resources being utilised and the introduction of new technology. Additional resources from pitt&sherry are being provided to give 24 hour Geotechnical QA/QC coverage.