sydney-city-centre-review-of-environmental-factors

to contamination or the generation of ASS
Identified those adverse impacts that would need safeguarding or managing
under the proposal.
The impact assessment considered the ability for various construction activities to
affect geological and soil values either directly or indirectly though migration
pathways. Consequently, the assessment considered the value that the geology and
soils provides and any change to these to these values as a consequence of the
proposal. Exposure, contamination, migration, and change in function or quality were
referred to when undertaking the assessment.
6.8.2 Existing environment
Regional geology (solid and drift)
Three geological units underlie the site. In sequence, they comprise:
Quaternary deposits (drift): silty-to-peaty quartz sand, silt and clay
Triassic Ashfield shale (drift): located directly on top of eroded Hawkesbury
sandstone, comprising black mudstones and grey silty shales with frequent
sideritic (iron-rich) clay ironstone bands
Triassic Hawkesbury sandstone (solid): medium-to-coarse grained quartz
sandstone, very-minor shale and laminate lenses.
There are two distinct lenses of quaternary deposits around Ultimo, Haymarket and
Chinatown. Surry Hills and Hyde Park are immediately underlain by Ashfield Shale
whilst the remainder of the central and northern city centre is immediately underlain
by Hawkesbury Sandstone. The majority of the proposal footprint is therefore
underlain by Hawkesbury sandstone, with the exception of the locations listed in
Table 6-51.
Table 6-51
Geological conditions other than Hawkesbury Sandstone
Work site Affected intersections/roads Geology
All sites
All sites excluding the exceptions
below
Hawkesbury
Sandstone
S1: Sussex Street G: Goulburn Street intersection Quaternary drift
deposits
S3: Pitt Street A: Liverpool Street intersection
B: Northern section Liverpool Street
to Goulburn Street
E: Campbell Street intersection
F: Campbell Street to Hay Street
G: Hay Street intersection
Ashfield shale
Quaternary drift
deposits
S5: Broadway Entire work site Quaternary drift
deposits
C2: College Street Entire work site Ashfield shale
C1: Wentworth Avenue Entire work site Ashfield shale
Sydney City Centre Capacity Improvement 374
Review of Environmental Factors