Impacts on the environment – Seaforth and Manly Dam
Construction is planned to widen the full length of the Wakehurst Parkway from Warringah Rd to 4 lanes, and a tunnelling site near Kirkwood St, Seaforth. This area covers a section of the Duffys Forest Ecological Community, a site with many highly endangered plant species, and a type of native bushland that is near extinct due to land clearing, development and weed infestation(1).
The EIS reveals that 1979 mature trees will be removed in Garigal National Park / Bantry Bay and Manly Dam Reserve(5) with replacement planting for only 339(6), replacing mature trees with only young saplings.
The site is also within the Manly Dam Catchment zone. Many years of construction run-off is a significant risk to the creeks and riparian zones near waterways that flow into Manly Dam, into Burnt Bridge Creek and into Manly Lagoon, a catchment already under considerable strain.
Fauna assessed in the area include numerous threatened species – including the Eastern Pygmy-possum, Powerful Owl, Rosenberg’s Goanna, Large-eared Pied Bat, Grey-headed Flying-fox, Red-crowned Toadlet, and the rare Galaxias brevipinnis, a climbing fish that is unchanged by evolution since the Gondwana era 60 million years ago.
The EIS states “Fauna can be sensitive to elevated noise, changing their behaviour and impacting their physiology… Fauna may initially desert the immediate area at the start of excavation activities due to increased noise and vibration levels… However, due to the extent of adjoining habitat, the initial displacement from the immediate area could become permanent. For less mobile species or breeding individuals, the effects of the high noise levels may be more acute.”(4).
In other words, more mobile species would most likely stay away from the area – but the assumption that there is plenty of surrounding bushland without competiton for territory or resources with other animals is contentious. It is also an injustice that less mobile and breeding animals unable to move are left to suffer destruction of habitat, noise, vibration, lighting at night, dust and potentially contaminated run-off water.

Eastern pygmy-possum and Grey-headed flying fox
Also impacted by the construction at Seaforth are numerous ancient Aboriginal rock carvings and middens. A government blueprint warned that the tunnel project would lead to some destruction that “cannot be avoided” and that “it will be difficult to justify major impacts” to the sites of high cultural significance to indigenous people. At these sites, the blueprint suggests excavating and removing the objects – an option unacceptable to indigenous leaders(2).
The EIS states “The Wakehurst Parkway landscape region is particularly significant because of the Hawkesbury Sandstone and its association with known Aboriginal rock engravings”(7). Within 50 metres of the footprint of the project, there are 11 sites of Aboriginal cultural heritage including rock art, engravings and rock shelters that are vulnerable to vibration impacts.
The reason these areas have not been developed in the past is because we used to value our natural and indigenous heritage, and protect endangered flora and fauna – do we still value these things?
A video produced by Save Manly Dam Bushland, shows the full extent of what is at risk by the tunnel project.
It can be viewed here: https://tinyurl.com/SaveManlyDamBushlandTunnel