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

Table 6-54
Excavations required below the road base course and associated
contamination risk
Location and associated contamination risk
S4: Ultimo Road
A: Harris Street intersection
Walls Engineering co, The Dairy Farmer
Co-operative, cold store, workshop, boiler
room, motor transport building
S5: Broadway
C: Wattle Street intersection
Manmade fill
D: Abercrombie Street intersection
Manmade fill
The above locations and wider development history across the city centre present a
limited human health risk. The likelihood of such an impact is assessed as low or
negligible due to the limited number of recorded contaminated sites in an area that is
well-understood, mapped and recorded.
Whilst there is the potential to contaminate the soil and pollute the underlying
groundwater during construction through accidental spillages, standard management
controls that are widely adopted and proven to be successful in their implementation
would reduce the likelihood of such an impact occurring (refer to section 6.7.4). The
impact could potentially cover a wide area, as the soils and geology are permeable.
This could provide a pathway for the contaminants to migrate from the work sites to
either the underlying groundwater or Sydney Harbour, as these waters are
hydraulically connected (refer to section 6.7.2).
Sediment laden runoff and dust generation
There is an erosion hazard associated with the majority of the soils underlying the
proposal footprint. This is discussed specifically in section 6.7.3. Dust impacts and
risks are discussed in section 6.12.2.
Acid sulphate soils (ASS)
Existing ASSs have the potential to be liberated into the surrounding soil and water
environments. In addition, potentially acidic soils can oxidise and develop into actual
ASSs through ground disturbance and/or changes in water levels.
As reported in Table 6-53, the majority of the proposal footprint falls within the lowest
ASS classification (ie class 5). Work proposed at work sites NW2: King Street and
R3: Sussex Street would occur over soils in ASS risk category class 1 and class 2
(ie with a higher ASS risk). The only potential risk of ASS being disturbed and
liberated would be due to the need to undertake ground excavation work in either of
these locations. Specifically:
At NW2: King Street this would be restricted to the proposed drainage
modification, traffic signal relocation and general signage relocation (refer to
Table 3-3)
At R3: Sussex Street this would be restricted to proposed general signage
relocation (refer to Table 3-4)
Consequently, the risks of an associated ASS impact are assessed as low-tonegligible
however not discountable.
Sydney City Centre Capacity Improvement 379
Review of Environmental Factors