Government informs the community that usage of Spit Reserve West will not be impacted, yet the constructions will involve extensive noise and truck movements for an estimated 3 years of construction, severely impacting the amenity of the reserve, marinas, restaurants and surrounding residential areas of both the reserve and the tunnel site.
There is also significant risk to Middle Harbour from disturbance of sediment according to secret government documents leaked to the media. “Another underwater tunnel…connecting Northbridge to Seaforth could also create a plume of turbid contaminated water”(1).
When sediments are disturbed, devastating impacts could be forced upon the seagrass, aquatic life including endangered marine species such as the White’s seahorse(2), and people enjoying swimming, boating and fishing in the surrounding areas of the Spit, Clontarf, Beauty Point and Sailors Bay.
Other effects to tidal flows, sediment accumulation and aquatic life caused by the location of the tunnel tubes are unknown at this stage.
The particular design that has been selected is a cheaper option, with greater impacts upon residents and the environment. The tunnel could be built by tunnelling under the harbour the same as under land, eliminating the need for coffer dams and a construction site at Spit Reserve West entirely, but this design has been rejected by government.
The tunnel is a major construction project with significant negative impacts locally, and yet government estimates of traffic benefits are only a 15% reduction in traffic on the Spit Rd/Military Rd corridor (as estimated 63% of existing traffic comes from the Mosman area, versus 37% from the Northern Beaches).