For the property developer of a site at the end of Blacks Road in Greenhithe to have access to the whole of his site, with the intention of creating 40 residential sections, the installation of a culvert or bridge to span a stream running through the middle of his land was required. With the Auckland City Council placing huge ecological value on the stream, various options were considered taking into account a variety of factors.
“Providing the fish passage through the culvert was a key issue when reviewing culvert options for the stream,” said Mike Lee from Airey Consultants Ltd. “The bottom of the stream had to remain open. We considered a traditional concrete structure but it would have been very costly and time consuming for all.”
With height of any structure another requirement, Airey Consultants settled on a Multi-plate™ Steel Arch from CSP Pacific.
“We were involved right from the beginning of the project with Airey Consultants and J W Neill Contractors to choose the right shape of structure,” says Mo Yang, Product Support Engineer for CSP Pacific. “There is limited head room and with the requirement to retain a natural stream bed an 8.2m long 6.0m span 2.4m rise galvanised Steel Multi-plate™ arch was ordered.”
“This was quite a complicated bit of engineering as we also had to install a very large retention tank and we needed a specific height to assist with the approaches to the culvert from both sides,” says Paul Cato, Director of J W Neill Contractors Ltd.
“We manufactured and delivered the Multi-plate™ in a very good time,” adds Mo. “J W Neill Contractors installed the structure in early January. We even went along with our pry bars to assist.”
“We should have everything completed in early March,” explains Paul. “ Lead time for delivery and the installation time for the arch itself on piled foundation beams was pretty quick really. It will look really good when completed as there is old fashioned style rock work being used as facing for the arch end walls. Everyone is very pleased with the outcome - including the fish.”