15.3 Assessment of potential construction impacts
Erosion and sedimentation
Construction of the project has the potential to result in erosion and sediment migration. Surface disturbance and vegetation removal exposes soils and may weaken surface soil structure. This could lead to erosion sedimentation and soil slippage within and around waterways and slopes in the study area, particularly during periods of high wind or rainfall. Areas of high erosion potential are at a higher risk of being subject to erosion and sedimentation. These areas are identified in section 15.2.1.
Uncompacted or unconsolidated materials (such as excavated and stockpiled soils) have the potential to leave construction areas during rain (through surface water run-off) causing downstream sedimentation. Sedimentation in natural waterways can result in reduced water quality as well as smothering of vegetation and clogging of channels, impacting the natural flow paths of the waterway.
During construction, soil erosion would be adequately managed in accordance with Managing Urban Stormwater: Soils and Construction Volume 1 (Landcom 2004) and Managing Urban Stormwater: Soils and Construction Volume 2 (NSW Department of Environment and Climate Change 2008a), commonly referred to as the ‘Blue Book’. The number, location and size of sediment basins would beconfirmed during detailed design. The Blue Book recommends that where receiving waters are sensitive, sediment basins should be sized for an 80th percentile or 85th percentile five-day rainfall depth for disturbance periods of less than or greater than six months respectively.
Erosion and sediment control would be focussed on areas of surface disturbance (ie surface road works, construction ancillary facility sites and areas of excavation and vegetation removal). Particular emphasis would be given to areas of surface disturbance near waterways, including at Rozelle Bay, where Whites Creek naturalisation and drainage works and Easton Park drain outfall works would be undertaken. These measures would minimise the potential for sedimentation at Rozelle Bay.
There is a risk that any erosion and/or runoff within the Rozelle Rail Yards could be contaminated. Further details about water management within the Rozelle Rail Yards during construction are provided in Chapter 16 (Contamination). To help avoid and minimise these potential impacts, a soil conservation consultant would be engaged to provide input during detailed design so as to minimise the potential for erosion and sediment migration, from the Rozelle Rail Yards specifically. The soil conservation consultant would provide input to a Construction Soil and Water Management Plan
(CSWMP) which would form part of the Construction Environmental Management Plan (CEMP) that would be prepared during detailed design.
Construction of the project has the potential to contribute to urban salinity through soil compaction at areas of surface disturbance, such as the construction ancillary facility sites, which can restrict groundwater flow and result in a concentrate of salt in one area. As outlined in section 15.2.1, urban salinity is not considered a significant concern within the project footprint.
Acid sulfate soils
The risk of acid sulfate soil varies across the project footprint. There is a high probability of encountering these soils around Rozelle Bay, Manning Street at Rozelle and St Peters interchange (see Figure 15-4).
Further soil testing would be conducted in areas with a high risk of acid sulfate soils prior to disturbance to confirm the presence of acid sulfate material. Testing would be carried out in areas identified as containing acid sulfate soils (or potential acid sulfate soils) as identified in section 15.2.1 including:
- Rozelle civil and tunnel site (C5)
- The Crescent civil site (C6)
- Bioretention facility at Manning Street in Rozelle
- Campbell Road civil and tunnel site (C10).
If acid sulfate soils are identified, they would be managed in accordance with the Acid Sulfate Soil Manual (Acid Sulfate Soil Management Advisory Committee 1998). The manual includes procedures for the investigation, handling, treatment and management of such soils.
Appropriate measures to manage acid sulfate soils are provided in section 15.5. Further measures to manage acid sulfate soils would be included as part of the CSWMP which would form part of the CEMP.
15.3.2 Water quality
Discharge of tunnel wastewater
During construction, tunnelling works would result in large volumes of wastewater being generated from the following sources:
- Groundwater seepage
- Rainfall runoff into tunnel portals and ventilation shafts
- Machinery washdown runoff
- Heat and dust suppression water.
Most of the wastewater generated during tunnelling would be collected from groundwater seepage. Estimated volumes of construction wastewater are included in Chapter 23 (Resource use and waste minimisation).
There is the potential for groundwater that seeps into the tunnels and other areas of excavation during construction to contain elevated levels of salinity. Existing groundwater quality along the tunnel alignments is variable, with Ashfield Shale typically being more saline than Hawkesbury Sandstone. Groundwater closer to Sydney Harbour and Botany tends to be more saline due to increased tidal influences. In low lying areas, groundwater may also be acidic due to acid sulfate materials.
However, considering the total amount of groundwater tunnel ingress, saline groundwater would make up a small fraction of the total volume. Further discussion around the quality of discharged groundwater is included in Chapter 19 (Groundwater).
Previous and current land use practices, including light industrial activities, may have introduced contaminants such as hydrocarbons or heavy metals, which could impact groundwater quality at some locations. The use of chemicals in the treatment and curing process of concrete, as well as the concrete dust itself, could also result in tunnel wastewater having increased alkalinity.
Groundwater monitoring carried out for the project indicates that there are elevated levels of ammonia, total nitrogen and total phosphorus compared to ANZECC (2000) guideline levels (marine, freshwater and recreational protection levels). Other heavy metals including copper, chromium, lead, nickel and zinc were also recorded at elevated levels on a limited number of occasions (refer to Chapter 19 (Groundwater)). Tunnel wastewater, if discharged untreated or poorly treated, has the potential to impact the receiving waterways by introducing increased nutrient loading and result in algal growth with increased risk to human health. There is also potential for reduction in visual amenity and impacts on aquatic species as a result of heavy metal or other toxicants.
The total volume of wastewater generated during construction would depend on construction activities taking place, the amount of groundwater infiltrating the tunnel, and the length of the tunnel that has been excavated. Indicative daily volumes of wastewater at each site and associated indicative discharge points are summarised in Table 15-10.
Tunnel wastewater would be treated prior to discharge (or disposal) to minimise impacts on receiving waterways, including Dobroyd Canal (Iron Cove Creek), Hawthorne Canal, Whites Creek, Easton Park drain, Johnstons Creek, Rozelle Bay, Iron Cove, White Bay and Alexandra Canal.
Table 15-10 Estimated daily discharge rate (kL/day) and indicative discharge points for construction wastewater
Site Estimated daily discharge rate (kL/day)
Indicative discharge points
Wattle Street civil and tunnel site (C1a)
Managed by Haberfield civil and tunnel site
Discharges to a stormwater pipe under Parramatta Road that connects to Dobroyd Canal Iron Cove Creek)
Haberfield civil and tunnel site (C2a) 1,200
Discharging to a stormwater pipe under Parramatta Road, connected to Dobroyd Canal (Iron Cove Creek)
Northcote Street civil site (C3a)
Managed by Haberfield civil and tunnel site
Discharges to a stormwater pipe under Parramatta Road that connects to Dobroyd Canal (Iron Cove Creek)
Parramatta Road West civil and tunnel site (C1b)
1,200 Discharging to a stormwater pipe under Parramatta Road that connects to Dobroyd Canal (Iron Cove Creek)
Haberfield civil site (C2b) Managed by Parramatta Road West civil and tunnel site
Discharging to a stormwater pipe under
Parramatta Road that connects to Dobroyd Canal (Iron Cove Creek)
Parramatta Road East civil site (C3b)
Managed by Parramatta Road West civil and tunnel site
Discharging to a stormwater pipe under Parramatta Road that connects to Dobroyd Canal (Iron Cove Creek)
Darley Road civil and tunnel site (C4) 700 Existing drainage system draining to
Hawthorne Canal Rozelle civil and tunnel site (C5) 2,400
Existing drainage system at City West Link draining to Rozelle Bay
Easton Park drain discharging to Rozelle Bay
The Crescent civil site (C6) 10 Existing drainage system at City West Link draining to Rozelle Bay
Victoria Road civil site (C7) 200 Existing drainage system at Victoria Road draining to White Bay Iron Cove Link civil site
(C8) 300 Existing drainage system at Victoria Road draining to Iron Cove
Pyrmont Bridge Road tunnel site (C9) 1,200
Discharging to a stormwater pipe under Parramatta Road, connected to Johnstons Creek
Campbell Road civil and tunnel site (C10) 1,200 Discharging to a stormwater pipe connected to Alexandra Canal
During construction, the wastewater collected in the tunnel would be tested and treated at construction water treatment facilities prior to reuse or discharge. The type, arrangement and performance of construction water treatment facilities would be further refined during detailed design, and may consist of:
- Primary settling tanks/ponds to remove sand and silt sediment fractions as well as oil and grease
- A pH balance/metals oxidation tank with primary flocculation whereby individual particles of clay are clumped together
- Secondary flocculation tanks
- Clarifiers to remove sediment and residual oil
Temporary construction water treatment facilities within the construction ancillary facilities would be designed to treat dirty construction water and groundwater and would be based on the targets outlined in section 15.1.5, which would be refined during detailed design. The level of treatment provided would consider the characteristics of the waterbody, any operational constraints or practicalities and associated environmental impacts and be developed in accordance with ANZECC (2000) and in consideration of the relevant NSW WQOs.
Considering the highly disturbed nature of all receiving waterways and temporary nature of the construction phase, an ANZECC (2000) species protection level of 90 per cent for toxicants is considered appropriate for adoption as a discharge criterion, where practical and feasible. The discharge criteria for the treatment facilities would be finalised and included in the CSWMP.
Mobilisation of sediments and pollutants during surface works
Surface construction activities may disturb soils and other materials that have the potential to impact water quality if not effectively managed, including:
- Exposure of soils during earthworks has the potential to result in soil erosion and off-site movement of eroded sediments by wind and/or stormwater to receiving waterways
- Demolition works have the potential to disturb and/or spread sources of pollutants that could affect water quality (including asbestos and other contaminated building materials, hydrocarbons or fluids associated with demolition processes and dust)
- Disturbance of contaminated land, which could be mobilised by stormwater runoff and transported to downstream waterways, potentially increasing contaminant concentrations in the receiving environment (refer to section 15.3.1 and Chapter 16 (Contamination))
- Exposure of potential acid sulfate soils, which may result in generation of sulfuric acid and subsequent acidification of waterways and mobilisation of heavy metals into the environment if poorly managed
- Rinse water from plant washing and concrete slurries may contain polluting contaminants which, if discharged off-site, could impact on surface water quality
- Potential spills or leaks of fuels and/or oils from maintenance or re-fuelling of construction plant and equipment or vehicle/truck incidents could potentially be conveyed to downstream waterways via drainage infrastructure
- Disturbance of Whites Creek and Rozelle Bay during bridge construction works as part of the realignment of The Crescent and channel widening of Whites Creek to manage flooding and drainage and naturalisation works. This may lead to disturbance of contaminated sediments and erosion of exposed banks once the existing channel concrete lining has been removed (and prior to construction of the naturalised channel treatment)
- Construction of new stormwater outlets to receiving bays (Rozelle Bay and Iron Cove) would cause localised mobilisation of potentially contaminated sediments. Sediments settled on top of the hard, lined base of Whites Creek would also be disturbed.
Table 15-11 summarises the potential water quality impacts during construction of the project. These impacts are regularly encountered on major construction projects, are well understood and management measures are well developed and consistently applied to minimise impact during construction.
Residual impacts on water quality during construction
The proposed surface water management measures outlined in section 15.5 aim to minimise short term impacts on the receiving waterways during construction. With the implementation of the management measures, and in the context of the overall catchment, any potential short term impacts are unlikely to have a material impact on ambient water quality within the receiving waterways.
Therefore, the project is likely to have a negligible influence on whether NSW WQOs are protected (if currently met) or achieved (if currently not met) during construction.
Table 15-11 Construction surface water quality impact summary
Location Construction activities /incidents Potentially affected waterways Potential impacts
15.4 Assessment of potential operational impacts
Erosion and sedimentation
During operation of the project, there is potential for recently disturbed soils to be susceptible to erosion, particularly during initial periods of landscaping and re stablishment of vegetation. This may occur in areas where soft landscaping is proposed for the project, including open space areas at the Rozelle interchange, adjacent to disturbed areas, along embankments and in the reinstatement of temporary ancillary facilities where topsoil is settling and vegetation is establishing. Landscaping at the Rozelle interchange also presents the greatest risk of sediment loads entering waterways through the stormwater system, due to the extent of landscaping proposed and the proximity to waterways.
Soil stabilisation work may be required following construction to prevent further erosion, topsoil loss or soil migration. This work is likely to be required following severe storms. Measures to manage erosion will be included in the Operational Environmental Management Plan (OEMP).
15.4.2 Water quality
During operation, there is potential for surface water quality to be impacted by the following processes and activities:
- Increased stormwater runoff from an overall increase in impervious area
- Spills or leaks of fuels and/or oils from vehicle accidents and/or operational facility and equipment
- Erosion of recently disturbed areas resulting in sedimentation of waterways
- Scour and mobilisation of contaminated sediments at proposed new drainage outlet locations and increased flow to existing locations (eg Rozelle Bay and Alexandra Canal).
These processes and activities, and their potential impacts on surface water quality in the study area are described in more detail in the following sections.
Operational water quality
The project would increase impervious areas (such as road pavement) that would be exposed to direct rainfall and increase runoff volume and associated pollutant mobilisation. Runoff from road pavement would typically contain pollutants such as sediments, nutrients, oils and greases, petrochemicals and heavy metals, which could potentially impact on water quality when discharged into receiving waterways.
MUSIC modelling was carried out to assess the performance of the proposed water quality treatment measures against pollutant reduction targets (see section 15.1.7). A summary of the MUSIC modelling results are provided in Table 15-12. The modelling results for the main locations where water would be discharged (Rozelle Bay, Iron Cove, White Bay and Whites Creek) and for the project as a whole indicate that:
- The project would generally reduce the mean annual stormwater pollutant loads being discharged to the Sydney Harbour and the Parramatta River estuary, when compared to the existing conditions
- The project would generally reduce the mean annual stormwater pollutant loads being discharged to the five receiving waterways, when compared to the existing conditions (except for total phosphorus loading to Dobroyd Canal (Iron Cove Creek), which would be slightly higher than the existing loading)
- The stormwater mean annual pollutant load reduction targets (see section 15.1.5) would not be achieved for the project or for the individual catchments, based on the treatment measures that could practically or readily be implemented.
The pollutant load reduction targets were not achievable given the lack of available space within the highly constrained project footprint. Oversizing other treatment measures to offset the reduced treatment for the project is not practical within the available project footprint, given that improvements in treatment performance are reduced as treatment facility footprint increases. An increased treatment size at Rozelle would reduce the area available for operational road infrastructure and open space.
In these highly constrained areas, good practice treatment techniques would be deployed where feasible and practical, as outlined in section 15.5. By reducing the mean annual stormwater pollutant load compared to existing conditions, the project would provide a beneficial effect in terms of reducing stormwater pollutant loads to the Sydney Harbour and Parramatta River catchment.
Table 15-12 MUSIC modelling results for operational water quality (kilograms per year)
Stormwater runoff from the project would be controlled by a stormwater quality treatment system, designed in accordance with the project stormwater quality objectives based on pollutant load reduction consistent with the Sydney Harbour and Botany Bay water quality improvement plans rather than a specific rainfall event (see section 15.1.5). These would be developed during detailed design and included in the CSWMP. This would achieve the environmental outcome required from a treatment device and is standard practice for construction projects of this nature.
Where practical and appropriate, operational treatment systems would incorporate a high flow bypass for a minimum of a three-month annual recurrence interval. This would enable treatment of the majority of most runoff events, while protecting the treatment devices from scour or damage associated with larger rainfall events.
Refer to Appendix Q (Technical working paper: Surface water and flooding) for full details of the stormwater drainage infrastructure and proposed stormwater quality treatment systems.
Tunnel drainage and treatment
The tunnels would include drainage infrastructure to capture groundwater and stormwater ingress, spills, maintenance wastewater, fire suppressant deluge and other potential water sources. The two tunnel drainage streams are expected to produce flows containing a variety of pollutants that require slightly different treatment before discharge to manage adverse impacts on the receiving environment. The pre-treatment water quality of each wastewater stream is expected to vary considerably, and consequently it is likely that the two streams would need to be collected and treated
Tunnel wastewater from the mainline tunnels would be pumped to a water treatment facility at the Darley Road motorway operations complex (MOC1) at Leichhardt. Options for discharge of treated water from the Darley Road water treatment plant include:
- Direct discharge to Hawthorne Canal, which would require a pipe to be installed along Canal Road and the construction of a new outlet in the wall of the Hawthorne Canal
- Direct discharge to the existing stormwater pipework in an adjoining road (ie Canal Road), which would require a pipe to be installed to connect to existing piped drainage
- Direct discharge into the sewer system located on the site, which would require a Trade Waste Agreement with Sydney Water.
Further detail regarding these discharge options is included in Appendix F (Utilities Management Strategy). The preferred option for treated water discharge from the Darley Road water treatment plant would be confirmed during detailed design.
Tunnel wastewater from the Rozelle interchange tunnels and Iron Cove Link would be pumped to an operational water treatment facility at the Rozelle East motorway operations complex (MOC3), with flows being treated at the constructed wetland at Rozelle civil and tunnel site (C5) and then discharged into Rozelle Bay.
At the St Peters interchange, a small portion (around 1.6 kilometres) of tunnel would also drain to the New M5 operational water treatment facility at Arncliffe, draining to the Cooks River. Other sources of water captured by the tunnel drainage system (ie washdown or a spill) would be collected in one of the tunnel sumps, assessed to determine the source, tested, and either pumped to and discharged at the surface or removed directly from the sump by tanker for treatment, and disposal elsewhere.
The combined mainline tunnel (23 litres per second) and Rozelle interchange tunnel (22 litres per second) would generate up to around 1,418 megalitres per year of groundwater.
Tunnel wastewater treatment
Elevated metals and nutrients were recorded during groundwater sampling and groundwater was identified as brackish (refer to Chapter 19 (Groundwater)). Metal, nutrient and ammonia loading to Hawthorne Canal and Rozelle Bay is likely to increase as a result of the continuous treated groundwater discharges. To prevent adverse impacts on downstream water quality within Rozelle Bay and Hawthorne Canal, treatment facilities would be designed so that tunnel wastewater would be of suitable quality for discharge to the receiving environment.
The operational water treatment facilities would be designed such that effluent would be of suitable quality for discharge to the receiving environment and developed in accordance with the ANZECC (2000) and relevant NSW WQOs. The ANZECC (2000) ‘marine’ default trigger values for 95 per cent level of species protection are considered appropriate for establishing discharge criteria for parameters which require treatment, where practical and feasible (refer to Appendix Q (Technical working paper: Surface water and flooding)).
The project water treatment facilities would treat iron and manganese (as no ‘marine’ trigger value is available for iron and manganese; alternative discharge criteria are provided in Table 15-13). The proposed constructed wetland at Rozelle would provide ‘polishing’ treatment to treated groundwater flows from the Rozelle interchange and Iron Cove Link tunnels, which would likely remove a proportion of the nutrient and metal load. As no constructed wetland is proposed at Darley Road (due to space constraints), opportunities to incorporate other forms of nutrient treatment within the facility at Darley Road would be investigated during detailed design if subsequent groundwater monitoring indicates it may be required.
A qualitative assessment (refer to Appendix Q (Technical working paper: Surface water and flooding)) of the risk posed by treated groundwater discharges to ambient water quality within Rozelle Bay and Hawthorne Canal determined the following:
- Considering the groundwater quality and proposed treatment, impacts on ambient water quality within Rozelle Bay are likely to be negligible
- Considering the groundwater quality and proposed treatment, impacts on ambient water quality within Hawthorne Canal are likely to be negligible and localised to near the outlet.
Impacts associated with discharge quality from the Arncliffe operational water treatment facility were assessed as part of the New M5 EIS. No adverse impacts are likely to occur as a result of the minor additional flow (1.6 litres per second) draining to the Arncliffe operational water treatment facility.
Indicative operational discharge locations are provided in Figure 15-5.
Scour and channel geomorphology
There is potential for sediment to be scoured and mobilised where stormwater or wastewater is discharged to receiving waterways and bays including Hawthorne Canal, Dobroyd Canal (Iron Cove Creek), Rozelle Bay, Iron Cove and Whites Creek. This could increase turbidity and lead to mobilisation of contaminants that are bound to sediments.
The Whites Creek widening and improvement works would follow Sydney Water’s naturalisation works and extend between Rozelle Bay and the realigned The Crescent. The design of the naturalisation works would be finalised during detailed design, but are likely to incorporate features such as sandstone blocks and vegetated benches to provide ecological benefits to the channel. The proposed channel bed and bank treatments would be hard lined.
As a result, impacts on channel form and geomorphology are unlikely to occur once the works are complete. Any vegetated zones (eg benches) would be susceptible to erosion and would be protected during the vegetation establishment period. Management measures to minimise the potential for scour are outlined in section 15.5 and would be incorporated into the CSWMP.
Spills and leakages
Vehicle or plant and equipment leakages or a vehicle crash may cause spills of oils, lubricants, hydraulic fluids and chemicals during the operation of the project. Spills and leakages within the project footprint have the potential to pollute downstream waterways, as a result of being conveyed to waterways via the stormwater network. The severity of the potential impact would depend on the magnitude and/or location of the spill in relation to sensitive receivers, emergency response procedures and/or management measures implemented on site and the nature of the receiving environment.
Further discussion on accidental spills is included in Chapter 25 (Hazard and risk). Spill control measures, as outlined in section 15.5, would be implemented to reduce and manage the potential for environmental impacts to occur.
Residual impacts on water quality during operation
As discussed in section 15.2.2, receiving waterways in the study area do not achieve all the Sydney Harbour and Parramatta River catchment WQOs, with records of elevated levels of some heavy metals, nutrients, turbidity and pH. MUSIC modelling carried out indicates that the project would reduce the stormwater pollutant loading to the receiving waterways when compared to the existing conditions. Therefore, residual impacts on receiving waterways are anticipated to be negligible and/or beneficial. The project is not expected to worsen the existing conditions of receiving waterways.
Tunnel water would be treated, and spill controls and water quality monitoring would be implemented to manage operational impacts on ambient water quality within the receiving waterways. With consideration to groundwater quality, proposed treatment and receiving water quality, residual impacts associated with treated tunnel water discharges to ambient water quality are likely to be negligible.
As no constructed wetland is proposed at Darley Road, opportunities to incorporate other forms of nutrient treatment (eg ion exchange or reverse osmosis) within the water treatment plant at Darley Road will be investigated during detailed design with consideration to the ongoing groundwater quality monitoring and other factors such as available space, increased power requirements and increased waste production.
In the context of the entire catchment draining to Sydney Harbour, the project is likely to have a negligible influence on achieving the Sydney Harbour and Parramatta River WQOs.
15.5 Environmental management measures
Management measures would be implemented to avoid, minimise or mitigate impacts on soil and water quality within the study area. These management measures are outlined in Table 15-13.
Table 15-13 Environmental management measures – soil and water quality
Impact No. Environmental management measure Timing Construction
Impacts on surface water quality:
SW01 A CSWMP will be prepared for the project. The plan will include the measures that will be implemented to manage and monitor potential surface water quality impacts during construction. The CSWMP will be developed in accordance with the principles and requirements in Managing Urban Stormwater – Soils and Construction, Volume 1 (Landcom 2004) and Volume 2D (DECCW 2008), commonly referred to as the ‘Blue Book’.
SW02 A program to monitor potential surface water quality impacts due to the project will be developed and included in the CSWMP. The program will include the water quality monitoring parameters and the monitoring locations identified in Annexure E of Appendix Q (Technical working paper: Surface water and flooding) to the EIS
where appropriate. The monitoring program will commence prior to any ground disturbance to establish appropriate baseline conditions and continue for the
duration of construction, as well as for a minimum of three years following the completion of construction or until the affected waterways are certified by a suitably qualified and experienced independent expert as being rehabilitated to an acceptable condition (or as otherwise required by any project conditions of approval). Further details to be included in the program are outlined in Appendix Q (Technical working paper: Surface water and flooding).
Sedimentation of waterways:
SW03 Erosion and Sediment Control Plans (ESCPs) will be prepared for all work sites in accordance with the Blue Book. ESCPs will be implemented in advance of site
disturbance and will be updated as required as the work progresses and the sites change.
SW04 A soil conservation specialist will be engaged for the duration of construction to provide advice regarding erosion and sediment control.
SW05 The extent of ground disturbance and exposed soil will be minimised to the greatest extent practicable to minimise the potential for erosion.
SW06 Disturbed ground and exposed soils will be temporarily stabilised prior to extended periods of site inactivity to minimise the potential for erosion.
SW07 Disturbed ground and exposed soils will be permanently stabilised and proposed landscaped areas will be suitably profiled and vegetated as soon as possible following
disturbance to minimise the potential erosion.
Impacts on the form and aquatic habitat of Whites Creek:
SW08 The proposed bridge crossing over and widening of Whites Creek, including all associated temporary and permanent infrastructure, will be designed and
constructed in a manner consistent with:
- NSW Guidelines for Controlled Activities Watercourse Crossings (DPI 2012)
- Why do Fish Need to Cross the Road? Fish Passage Requirements for Waterway Crossings (Fairfull and Witheridge 2003)
- Policy and Guidelines for Fish Friendly Waterway Crossings (NSW Fisheries February 2004)
- Policy and Guidelines for Fish Habitat Conservation and Management (DPI Fisheries, 2013).
Appropriate fish passage will be provided for crossings of fish habitat streams.
SW09 Consultation will be undertaken with Sydney Water regarding the timing of the works at Whites Creek and compatibility of the proposed design and Sydney Water’s
Impacts on water quality from the discharge of treated wastewater:
SW10 Temporary construction water treatment plants will be designed and managed so that treated water would be of suitable quality for discharge to the receiving environment. The level of treatment provided will consider the characteristics of the waterbody, any operational constraints or practicalities and associated environmental impacts and be developed in accordance with ANZECC (2000) and with consideration to the relevant NSW WQOs and Protection of the Environment Operations Act 1997 (NSW).
An ANZECC (2000) species protection level of 90 per cent is considered appropriate for adoption as discharge criteria for toxicants where practical and feasible.
The discharge criteria for the treatment facilities will be included in the CSWMP.
Impacts on water quality from disturbance of acid sulfate soils:
SW11 Procedures, prepared in accordance with the requirements of the Acid Sulfate Soil Manual (Acid Sulfate Soil Management Advisory Committee 1998), will be included in the CSWMP and implemented in the event that acid sulfate soils, rocks or monosulfidic black oozes are encountered during construction of the project.
Impacts on surface water quality:
OSW12 Stormwater from the project will be treated prior to discharge. Where space is available, bioretention systems or constructed wetlands will be installed. Where
space is not available, other smaller devices, such as proprietary stormwater treatment devices, will be installed. The final design of treatments will be supported
by MUSIC modelling and water sensitive urban design principles.
OSW13 Maintenance requirements for all stormwater treatment systems and devices installed as part of the project will be identified and included in relevant operational
OSW14 Spill containment will be provided on the motorway. Spill management and emergency response procedures will be documented in the OEMP or Emergency Response Plan.
OSW15 The constructed wetland at the Rozelle interchange will be appropriately designed to cater for the continuous flow of treated groundwater from the water treatment plant and onsite stormwater flows.
OSW16 The operational water treatment facilities will be designed
such that effluent will be of suitable quality for discharge to the receiving environment.
Discharge criteria will be developed in accordance with the ANZECC (2000) and relevant NSW WQOs, including the following discharge criteria:
- 0.3 milligrams per litre for iron
- 1.8 milligrams per litre for manganese.
The discharge criteria for the treatment facilities will be included in the OEMP.
Sedimentation or scouring effects at discharge locations:
OSW17 New discharge outlets will be designed with appropriate energy dissipation and scour protection measures as required to minimise the potential for sediment
disturbance and resuspension in the receiving waters. Outlet design and energy dissipation/scour protection measures will be informed by drainage modelling.
OSW18 Existing drainage outlets that will be subject to increased inflow from the project will be assessed. If necessary, energy dissipation or scour protection will be added to
prevent sediment disturbance and resuspension in receiving waters.