Air in the Tunnel will be exhausted
from the top of the northern pylon of the Harbour Bridge, necessitating
some internal changes - but not external changes - to the pylon. Fresh
air will be supplied to the Tunnel from an air intake structure located
in Bradfield Park.
There is a potential for adverse air
quality impact at the southern portal in the Domain. This situation
could be avoided by limiting the number of vehicles entering the Tunnel
through electronic monitoring and electronic traffic signals and signs.
The need is expected to arise only occasionally in the year 2000 and
for a short duration each time.
The Department of Environment and Planning
argued that the regional air quality would be worse with the Tunnel
than without it but that the Tunnel could not be rejected on air quality
The air intake structure in Bradfield
Park will alienate a small proportion of parkland and cause changes
in how the park is used and significant local visual impact due to both
the visibility of the site and the transformation of an estimated three
percent of the park. Planting will reduce visual impact of the structure.
In the area of the Domain adjacent to
the existing Domain Tunnel there will be some regrading works, loss
of approximately six trees, one of which is of particular significance
(Melaleuca), and the construction of retaining walls. These changes
will result in significant local visual impacts and a possible change
in recreational use of the area. The affected trees will be transplanted
The impact on the marine ecology comes
mainly from dredging and blasting on the Harbour bottom. The EIS argued
that whilst some marine organisms would be lost they were plentiful
in the area and their loss would not be significant. The disturbance
from construction would also disturb some sediments containing toxic
waste and heavy metal levels were expected to rise.
A committee of review found that the
EIS did not adequately study the impact of the construction of the Tunnel
on the marine environment.