Click the photograph for a enlarged view
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Physical Environment
Landscape
Coniston Beach consists of Quaternary
sand dunes (Wollongong Geological Series Sheet SI 56-9) which are aeolian
(wind formed) north-south oriented dunes 5-15m high. Soils consist of deep
calcareous sand on the beaches, siliceous sands on the foredunes and isolated
podzols in the swales (Patterson Britton & Partners, CEE & AWT 1998).
Bathymetry &
Substrate
The outfall is located
approximately 200m offshore of Coniston Beach in 7m water depth close to a
relatively large area of rocky reef. The soft seabed in the vicinity of the
outfall ranges from fine to medium sands nearshore (to approximately 7m water
depth) to coarse sand, shell grit and clay further offshore. Fine sediments
occur at the 10m contour, while coarse sediments are found at the 16m depth.
Sediments at 18m and 20m water depth are coarse sand, shell grit and gravel.
Small areas of clay were observed approximately 600m offshore and to the
south-east of the existing outfall and 300mm below the sand 50m south of the
reef on the 18m depth contour. A large irregular sandstone reef extends
immediately offshore from the existing outfall from the 7m depth contour to
the 20m depth contour. This reef extends approximately 250m north and south of
the existing outfall alignment. Within the reef, there are rock outcrops and
pinnacles, areas of flat rock 10 to 30m across and sand patches (Patterson
Britton & Partners, CEE & AWT 1998). To the north of Coniston Beach is
Wollongong Beach and then Flagstaff Point. To the south is a boulder seawall
(the Port Kembla Coal Loader Stockpile) and Port Kembla Harbour.
Currents, Winds and Waves
Climate, wind and oceanographic data
for the area are available from AWT (1992a) and Patterson, Britton &
Partners, CEE & AWT (1998).
Recent studies by Lawson and Treloar
(1998 cited by Sydney Water Corporation 1999) indicate:
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a net current to the south averaging
4 cm/s.
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southerly currents occurred much more
frequently than northerly currents, which in turn occurred more frequently
than offshore/onshore currents.
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measurements over a one month period
revealed that currents were weak, with longshore currents averaging 4cm/s
and onshore/offshore currents averaging 2cm/s.
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Further oceanographic data
using a moored acoustic doppler current meter (ADCP) 800m due east of
Coniston Beach is described by OFS (1998).
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