Nickel West Kambalda

Structural Design & Assessment, Structural Investigation

NRM Consultants as structural consultants to Fressyinet Australia undertook a structural review of a 50m diameter concentrator tank at the Nickel West works in Kambalda, WA.  NRM Consultants were engaged to undertake a structural assessment on the 50-year-old concrete tank which had undergone a severe degree of corrosion, delamination, splitting and deformation.  We were then engaged to provide a structural solution to remediate and extend the life of the tank.

Nickel West is a fully integrated mine-to-market business operating in various locations across Western Australia.  The concentrator tank was a central part of the operation of the facility in Kambalda, the tank could only be shut down for a short period during the site maintenance schedule.

Freyssinet Australia is a multifaceted contractor providing innovative solutions from design through to implementation for specialist civil engineering, building post-tensioning and remediation. While the company has maintained a presence within the country since 1953 through licence holders, Freyssinet as it exists today was established in 1983, with the acquisition of a fifty per cent stake holding in the then established Austress PCS by Freyssinet International, a global network based in France. In 2006, Freyssinet had full ownership of the organisation.

The company’s title was changed to Freyssinet in 2009, after their merger with Soletanche Bachy and Freyssinet’s worldwide launch of a new business image and logo. Even at the time when Freyssinet’s Australian interests were entirely managed through their licensee, the company has consistently sustained a deep involvement within the country’s market.

Challenge

The challenge was extensive as access to the top of the tank and the obvious health and safety issues were extremely important.  Health and safety regime hindered some access and the internal side of the tank could not be assessed. Our access during the works was limited to the outer perimeter of the structure and therefore observing the corrosion of the sludge channels was difficult.

 

An extensive drummy assessment was undertaken on the structure, and associated potential corrosion tests were undertaken to assess the corrosion in the circular reinforcement.  We built up a corrosion map of the reinforcement and identified the risk to the structure from the current cracking and corrosion of the reinforcement.  We even noted a wobble or bulge in the circular frame which would introduce bending and future deformation on the circular frame leading to a potential collapse.  We assessed the risk of the deformation and implied that this would continue.  Our assessment indicated the structure was at the potential risk of structural failure.  A degree of computer modelling was undertaken to identify the structural risk of the cracking and splitting noted.  The structure was coming to the end of its structural life.

Solution

NRM Consultants provide a state-of-the-art remediation package to close up the structural cracking using best practice solutions.  We developed a post-tension cable solution with Freyssinet Australia to accommodate the hoop stresses with the tank and to bridge the corroded reinforcement