Project Client
Whakatāne Mill Limited
Background
‘Saveall’ is shorthand for the final waste collection stage of the paper making process. The saveall structure consists of an elevated disk filter supported by a steel frame and a series of distilling tanks and pumps, which are all founded on a piled concrete raft.
Project Objective
Preliminary investigations showed that the site soil was contaminated with asbestos and historic paper-making process residues. Before construction started, all the contaminated soil was removed to a licensed landfill.
Piling started on November 3rd, 2022, after the soil had been removed and existing services had been relocated. The piles were originally specified as reinforced bored piles, but were then changed by the contractor to Continuous Flight Auger (CFA) piles.
CFA piles are bored and poured in a single pass, and the reinforcing cage is added immediately after. Problems were encountered due to a national shortage of Pulverized Fly Ash, resulting in a stickier concrete mix which made the reinforcing cage difficult to install.
The first pile’s reinforcing cage could not be inserted under self weight beyond 10 m depth, well short of the target 15 m depth, and so the cage was retrieved and the concrete drilled out before it set. A second pile had the same issue, but its reinforcing cage couldn’t be extracted and the entire pile was abandoned. That pile was replaced by two new adjacent piles which reached the required depth with the reinforcing.
After that difficult start the rest of the piles were successfully installed without further issues. TECL’s direction was essential to mitigating the consequences of the abandoned pile – we were able to immediately provide the appropriate solution to keep the project moving.
Project Details
| Project name: | Whakatāne Saveall Structure |
| Client: | Whakatāne Mill Limited |
| Location: | Coastlands, Whakatāne |
| Structure Size: | 110 m² raft, 15 m pile depth |
| Challenges: | Nationwide PFA shortage |
| Project Partners: | Mainstream Engineering |
Hugh Barraclough
Project Manager / Structural & Civil Engineer (CPEng)
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Email TECL directly and we’ll forward your enquiry to the most appropriate person.