16.3 Assessment of potential construction impacts

The project has the potential to generate contamination during construction and operation, including the potential to disturb existing contaminated lands at surface works locations.

16.3.1 Construction ancillary facilities

The assessment of impacts for surface works during construction is presented in Table 16-23. Site layouts showing construction work areas are shown in Chapter 6 (Construction work).

Table 16-23 Risk assessment for potential construction impacts

The Crescent civil site (C6) at Annandale

Site establishment
Utility works
Temporary stockpiling
Road works, including construction of a new road bridge over Whites Creek
Widening and improvement works along Whites Creek
Construction of the culvert below City West Link (Easton Park drain)
Construction and dewatering of coffer dam(s) in Rozelle Bay
Finishing works
Excavating, filling and gradingof disturbed areas
Landscaping and constructionof pedestrian and cyclist paths and bridges.

Previous investigations have indicated soil, sediment and groundwater contamination
associated with historical filling and more recent industrial/commercial maritime operation. There is an existing management plan to manage identified contamination on part of the site. Potential construction impacts include:

Impacts on site workers and the local community through contact with contaminants and asbestos released during demolition and ground disturbance works
Exposure of underlying ground surface during excavation resulting in the potential mobilisation of contamination
Contamination resulting from potential leaks and spills from equipment and plant
Erosion and off-site transport of sediment and contamination via overland flow and
stormwater runoff, affecting the water quality of Whites Creek and Rozelle Ba
Adverse impacts on the environment as a result of the inappropriate management of waste generated by construction activities
Direct contact, inhalation and ingestion risk to site workers from contaminated soil or hazardous building materials via dust
Adverse impacts on ecological receptors from the discharge of contaminated surface water and sediment to Rozelle Bay
Adverse impacts on ecological receptors from the mobilisation of disturbed contaminated sediment within Rozelle Bay
Cross contamination from the incorrect handling of contaminated soil, fill, sediment, groundwater and surface water
Accidental spills and leaks from equipment and plant used during construction
Disturbance of actual or potential acid sulfate soils at the western end of the site which could impact local soil and water quality.

Known to be mpresent and widespread Exposure pathway likely to be present High

Pyrmont Bridge Road tunnel site (C9) at Annandale

Demolition
Excavation for the temporary access tunnel
Minor road works

There are historical land uses within and surrounding the site which may have caused soil and potentially groundwater contamination. Further intrusive investigations would be required to assess the risk posed during construction.
Potential construction impacts include:

Direct contact, inhalation and ingestion risk to site workers from contaminated soil or hazardous building materials via dust
Discharge of contaminated surface water to the stormwater system and ultimately Johnstons Creek, which discharges to Rozelle Bay.

Potentially present and widespread Exposure likely to be present Medium

16.3.2 Tunnelling

A review of potential contamination sources along the tunnel alignment identified the presence of potential, current and former contamination sources. These are summarised in Appendix R (Technical working paper: Contamination).
During tunnel construction, groundwater would be extracted from the tunnelling process, which would subsequently require disposal. The extracted water would be either:

Treated onsite and then discharged to stormwater under an EPL or to sewer under a trade waste agreement
Transported to a liquid waste facility.

Potential impacts on receiving water bodies associated with the construction of new drainage outlets and drainage infrastructure adjustments and upgrades could occur at the following locations:

Rozelle Bay
Iron Cove
Whites Creek
Easton Park drain
Receiving waters of Sydney Harbour.

Potential pre-mitigation impacts on workers could include exposure to extracted contaminated groundwater from either direct contact or inhalation of vapours, or vapours encountered during tunnelling.
There is potential for shallow tunnelling, such as near portals, temporary access tunnels or cut-andcover tunnels, to encounter groundwater that is impacted from contamination from sources such as petrol stations with dissolved and undissolved petroleum hydrocarbon plumes or other industrial sources. The identified highest risk locations are considered to be:

Parramatta Road, Annandale: The temporary access tunnel connecting the mainline tunnel to the Pyrmont Bridge Road tunnel site (C9) passes directly south of the 7 Eleven service station that is presently under assessment by the NSW EPA under section 60 of the CLM Act. The temporary access tunnel may be relatively shallow as it passes the service station and could potentially intercept a dissolved or undissolved (ie LNAPL) petroleum plume
Wattle Street, Haberfield: The Wattle Street entry and exit ramps are located in an area historically occupied for residential land use in the suburb of Haberfield. There is potential for ACM and lead paint to be present in surface soils
Darley Road, Leichhardt: The temporary access tunnel to the Darley Road civil and tunnel site (C4) passes between former manufacturing businesses and former steel manufacturers and boiler makers. There is potential for metals, PAHs, TPH, asbestos, VOCs, SVOCs to be present in shallow surface soils and/or groundwater
Parramatta Road west, Ashfield: The temporary access tunnel to the Parramatta Road West civil and tunnel site (C1b) is generally located within the northern portion of the site and traverses north along Parramatta Road. There is potential for ACM (from demolition and redevelopment works along Parramatta Road and associated filling) and PAHs to be present in shallow surface soils and/or groundwater
Rozelle Rail Yards, Rozelle: previously identified LNAPL within the Rozelle civil and tunnel site (C5) could be impacted by dewatering for tunnelling around the Rozelle interchange and is likely to be encountered during future tunnelling/portal construction, if not remediated prior
Victoria Road, Rozelle: The Iron Cove Link tunnel between Darling Street and Terry Street passes beneath or directly adjacent to several service stations, some of which are presently under assessment by the NSW EPA under section 60 of the CLM Act, as well as several former dry cleaners
Campbell Road, St Peters: The tunnel portal area and temporary access tunnel within the former Alexandria Landfill at the New M5 St Peters interchange due to leachate and landfill gases. The tunnel at this section is shallow and would be exposed to landfill leachate if appropriate mitigation measures are not implemented.

With the exception of the former Alexandria Landfill (assessed as part of the New M5 project), other sections of the tunnel are at depths greater than 30 metres and therefore the likelihood of encountering plumes with high concentrations of contaminants is low given that deep contamination (greater than 30 metres below ground level) has generally not been identified along the proposed M4- M5 Link tunnel alignment. However, the extracted groundwater is likely to contain concentrations of metals and nutrients above background concentrations and low concentrations of chemical and petroleum hydrocarbon contaminants from the types of sources listed in the previous table. Notwithstanding, tunnels would be drained to construction water treatment facilities prior to discharge to receiving surface water bodies.
Dewatering during construction works may cause changes in the migration of plumes of contaminated groundwater by changing groundwater gradients and drawing the contamination towards the tunnel. This is most likely in areas where the tunnels are shallow and approaching the surface such as the temporary access tunnel at Parramatta Road, Annandale, and the Iron Cove section near and beneath Victoria Road at Rozelle. This is discussed further in Appendix T (Technical working paper:
Groundwater).
Temporary construction water treatment plants would be located at each construction ancillary facility where tunnelling would occur, and would be designed to treat construction water and groundwater inflows encountered during construction. The level of treatment would consider the characteristics of the water requiring treatment, operational constraints or practicalities, and associated environmental impacts. The treatment would be developed in accordance with ANZECC (2000) and with consideration to the relevant NSW Water Quality Objectives as discussed in Appendix Q (Technical working paper: Surface water and flooding).

16.4 Assessment of potential operational impacts

16.4.1 Permanent operational facilities

Potential contamination impacts associated with the presence of roads and permanent operational infrastructure is presented in Table 16-24. Leachate within the former Alexandria Landfill would be treated by the existing water treatment plant constructed for the New M5 project and discharged to sewer under the existing trade waste agreement with Sydney Water. Therefore, leachate within the former Alexandria Landfill does not form part of this assessment.

The Parramatta Road ventilation facility located adjacent to Parramatta Road between Wattle Street and Walker Avenue has been assessed as part of the M4 East project. The M4-M5 Link project includes the internal fit out of this structure.

The construction ancillary facilities that are not anticipated to be used for permanent operational infrastructure would be rehabilitated at the end of construction. Construction facilities that will not include new operational infrastructure are:

Northcote Street civil site (C3a)
Parramatta Road West civil and tunnel site (C1b)
Parramatta Road East civil site (C3b)
Pyrmont Bridge Road tunnel site (C9).

At the completion of M4-M5 Link construction the landscaping (where applicable) and residual land obligations as detailed in the M4 East and New M5 conditions of approval would be carried out by these respective projects. As such there are no anticipated operational impacts of these construction ancillary facilities during operation and these are not discussed further in this section.

Table 16-24 Risk assessment for potential operational impacts

The Crescent at Annandale

Road infrastructure
Pedestrian and cyclist paths Accidental leaks and spills on constructed roadways from vehicles and vehicle accidents.

Very unlikely and limited in extent Exposure pathway may be present, in the event of leaks and spills Low

16.4.2 Tunnels

During operation, groundwater seepage would need to be extracted from the tunnels, treated and discharged to receiving water bodies. As part of the tunnel design, some sections would be lined to reduce the ingress of groundwater into the tunnels.
Groundwater quality may be impacted along parts of the tunnel alignment due to overlying contamination sources impacting groundwater. An assessment of the expected groundwater seepage rates and groundwater drawdown which may have an effect on existing groundwater contamination plumes is provided in Chapter 19 (Groundwater).
The extracted groundwater could contain concentrations of metals and nutrients above background concentrations and low concentrations of chemical and petroleum hydrocarbon contaminants. Water collected from within the tunnels would be treated to an appropriate standard to prevent environmental harm prior to discharge (refer to Chapter 15 (Soil and water quality)). If not treated adequately, the discharge of the groundwater to receiving water bodies could contribute to poor water quality. However, the potential for this to occur is considered to be extremely low.
Tunnel drainage infrastructure would be designed to accommodate a combination of contaminated water ingress events including groundwater ingress, stormwater ingress at portals, tunnel wash-down water, fire suppressant deluge or fire main rupture and spillage of flammable and other hazardous materials. Separate sumps would be provided at tunnel sags, one to collect groundwater ingress and one to collect the other potential water sources. The two tunnel drainage streams from the mainline works would be pumped to a water treatment facility at Darley Road, Leichhardt. Potential discharge
and disposal options for treated flows from the facility are discussed in Chapter 15 (Soil and water quality).
Tunnel drainage for Rozelle would be pumped to a water treatment facility and constructed wetland at the Rozelle Rail Yards, with treated flows ultimately discharged to Rozelle Bay. Tunnel drainage from around one kilometre of the northbound and 600 metres of the southbound tunnel would be captured by the New M5 drainage system and conveyed to the New M5 operational water treatment plant at Arncliffe, which ultimately drains to the Cooks River.

An assessment of the potential impacts on the receiving bodies is provided in Chapter 15 (Soil and water quality).

16.5 Management of impacts

The mitigation and management measures provided in Table 16-25 would be implemented during construction and operation of the project to reduce or minimise the potential impacts created by contamination risks. These measures are expected to make the land to be used as part of the project suitable for the proposed end use. Potentially contaminated sites identified in section 16.2.14 would be subject to further investigation, remediation and/or management. Further details on the environmental management measures are provided in Appendix R (Technical working paper: Contamination).

An UDLP would be prepared for the project. Areas of land not required for the construction or
operation of the project but that have been identified as being subject to the UDLP would be
rehabilitated and landscaped to be consistent with the UDLP. Remaining project land would be rehabilitated and returned to finished levels generally consistent with the original ground surface. The future use of remaining project land would be outlined in the Residual Land Management Plan to be prepared for the project.
Wattle Street civil and tunnel site (C1a), Haberfield civil and tunnel site (C2a) and Northcote Street civil site (C3a) would be developed in accordance with the conditions of approval for the M4 East project. The Campbell Road civil and tunnel site (C10) would be developed consistent with the conditions of approval for the New M5 project.
Table 16-25 Environmental management measures – contamination
Impacts on site workers and/or local community through disturbance and mobilisation of contaminated material
CM01 Potentially contaminated areas directly affected by the project will be investigated and managed in accordance with the requirements of guidance endorsed under section 105 of the CLM Act.

This includes further investigations in areas of potential contamination identified in the project footprint. If contamination posing a risk to human or ecological receptors is identified, a Remediation Action Plan will be prepared.

Construction
CM02 Asbestos handling and management will be undertaken in accordance with an Asbestos Management Plan (as part of the Work Health and Safety Plan) as described in Chapter 23 (Resource use and waste minimisation).
Construction
CM03 A hazardous materials assessment will be carried out prior to and during the demolition of buildings. Demolition works will be undertaken in accordance
with the relevant Australian Standards and relevant NSW WorkCover Codes of Practice, including the Work Health and Safety Regulation 2011 (NSW).
Construction
CM04 The Construction Waste Management Plan for the project, prepared as described in Chapter 23 (Resource use and waste minimisation), will include procedures for handling and storing potentially contaminated substances.
Construction

CM05 Stockpile management procedures will be implemented to control dust, odour and cross contamination.
Construction
CM06 The discovery of previously unidentified contaminated material will be managed in accordance with an unexpected contaminated lands discovery procedure, as outlined in the Guideline for the Management of Contamination (Roads and Maritime 2013) and
detailed in the CEMP. The procedure will include:

Cease work in the vicinity
Initial assessment by an appropriately qualified environmental consultant
Further assessment and management of contamination, if confirmed, in accordance with section 105 of the CLM Act.
Construction

Impacts on soil and water quality through incorrect handling of contaminated material
CM07 A Construction Soil and Water Management Plan will be prepared for the project including procedures to manage potentially contaminated stormwater runoff and acid sulfate soils, as described in Chapter 15 (Soil and water quality).
Construction
CM08 Measures identified in Chapter 25 (Hazard and risk) will be implemented to appropriately store dangerous goods and reduce the potential for environmental contamination due to spills and leaks.
Construction
Accidental spills during operation

OCM09 Procedures to address spills, leaks and tunnel washing will be developed as part of an Operational Environmental Management Plan (OEMP) and implemented during operation of the project.
Operation