More than 3,200m3 of sand was dredged from the outer Hauraki Gulf and brought to Pt England to create a 250-metre long beach that could be used in all tides by the large catchment population. "Previously there was no beach whatsoever at high tide for people to access," said Lorenzo Canal Project Manager for Urban Solutions. "To ensure the newly deposited sand isn't eroded by the sea, Coastal Design Engineers Tonkin and Taylor designed a 45m groyne structure - a manmade naturalistic reef which mimics natural rock features - to be constructed to improve beach stability."
Choosing the right company to build the manmade reef was an important decision. Lorenzo explains, "we couldn't take the risk that we would end with something that looked more like an attraction at Disneyland so we recommended to the council that we use Ron Grosse from Landforms NZ who is vastly experienced in this area with amazing results."
"These structures have a function in keeping the beach stable but they also need to look as natural as possible," says Ron Grosse from Landforms New Zealand. "We took the visual cues from the Waitemata rock formations in the area and sculptured and shaped the structure to look like the real thing."
"Sprayed concrete was the only viable way to create the desired effect," says Andrew Porter National Sales Manager from Dricon. "Truck mixed ShotCrete was not an option due to the distance from the carpark, so Dricon's gunite mix was specified."
"Gunite has a far higher degree of accuracy for placing the concrete to sculpt and create the naturalistic sandstone rock formations," adds Ron. "Gunite also cures and hardens very rapidly so we can extend our spraying hours to work in with the tides allowing less breakdown from tidal effects creating a far lower environmental impact."
What is Dricon's gunite mix?
A dry mix method involving placing dry ingredients into a hopper and conveying them pneumatically through a hose to the nozzle. A nozzle operator controls the addition of water at the nozzle. The water and the dry mixture are not completely mixed in the nozzle, but mixing is completed as the mixture makes contact with the receiving surface. The advantage of using a dry mix process is that the water content can be adjusted instantaneously by the nozzle operator, allowing more effective placement in overhead and vertical applications without using accelerators.
For more information on Dricon's gunite mix call Andrew Porter, National Sales Manager for Dricon on 0800 800 576.
"During the construction stages we did receive various comments from locals and you could feel they weren't necessarily happy that we were interfering with their beach," adds Ron. "But since it has been completed, we get nothing but compliments on how natural and 'part of the landscape' this reef now looks. It's really good to hear. I am sure the new beach will be well frequented during the coming summer months."
