The Karaka Lakes and the Karaka Harbourside residential developments on the Hingaia Peninsula in South Auckland have been extremely popular, with new homebuyers flocking to the area. To keep up with demand more land is being made available at the Karaka Bookview development - just south of Karaka Lakes - at the end of Bay Vista Drive.
“To access the land beyond Bay Vista Drive a culvert was required to cross an existing stream,” explains Nev Smyth, Senior Engineer and Senior Associate at Harrison Grierson, consultants to the project. “We considered a concrete culvert but the Council requested that further options be considered to minimise the environmental impacts on the stream and maintain the natural stream substrate.“
Nev says other options were considered including a bridge that came with a fairly hefty price tag. “With the requirement to have the least impact on the stream bed possible, open-bottom structures were considered so the stream substrate would remain in place, minimising impacts to the existing flow regime. CSP Pacific’s Super•Cor™ Arch is larger than required for this location but their smaller Steel Multi-plate™ structure fitted the bill very well.”
“We helped with plans and supply of a 8m wide x 3m high and 50m long Multi-plate™ structure,” says Bruce Stephens, Regional Sales Engineer for CSP Pacific. “These types of structures are being considered more and more for a variety of projects due to, as in this case, their minimal impact on the environment and the fact they can be installed that much quicker than other culvert or bridge type options. They are a very economical, easily constructed option.”
Nev says that, in this case, concrete culverts would have taken significantly longer to install than the Multi-plate™. This is because the culvert could be constructed without any works in the stream bed and did not require diversion of the stream’s flow.
“I know this is a common saying but time is money and, in this situation, not only did the Multi-plate™ go together remarkably well, but there were other advantages in that we didn't need to divert the stream during construction - which was another tick in the environmental column on top of the time saved,” adds Nev.
“This is the first Multi-plate™ Structure we have ever installed,” says Aaron Abercrombie, Project Manager for Sam Pemberton Civil (Auckland) Ltd. “We were very glad that everything lined up as the thought of undoing 2000 bolts was certainly on my mind. The other thing was how quickly we got it together - in took nearly half the time we thought it would take.”
Aaron says they did a fair bit of work on the stream to allow the Multi-plate™ to be installed and to ensure it was upgraded to easily handle future flood events for the developing area.
“CSP Pacific were very helpful and supportive through the installation”, adds Aaron. “This system is new to all of us, but it was certainly worth the effort. I think we will be installing a lot more Multi-plate™ structures in the future.”
“I have endorsed this product as suitable for this project and I am glad it has proven to be the most appropriate and feasible engineering solution,” adds Nev. “For this project it has proved to be a very economical and simple system to install. This has been a very successful installation to date, and everyone is very happy with the outcomes.”