The first of two new trunk sewer tunnels has been completed in Browns Bay, New Zealand.
After five month’s of tunnelling, the 2.1m diameter Tunnelteq pipejack broke through to the reception shaft on 17 May. The tunnel route ran 400m northwards along the beachfront in North Shore City from a 7.5m deep caisson shaft, with only 3.5m of cover. A source told T&TI the face was sometimes in mixed conditions when it straddled the boundary between alluvial soils and underlying sedimentary rocks.
Dave Woods, North Shore City wastewater projects manager, said the US$9M scheme would “provide for increased dry-weather flows from expected future growth and also have the capacity to provide temporary storage during wet weather.”
Contractors, the Works Harker JV and engineers, Sinclair Knight Merz-Opus, are now focusing on the 600m long leg of tunnel that will run inland from the same caisson shaft.
