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EXPERT WITNESS PRESENTATION

North East Link Project - Surface Water

David FullerPrincipal Water Management and Technology

CONTENTS

• Overview and Summary– Surface water report– Peer review process– Water quality, geomorphology, flooding

• Detailed presentation– Water quality– Geomorphology– Flood risk– Response to Key Submissions– Conclave report – Refinement of EPRs– Conclave report – Other matters– Reports by Mr Cawood (Carey Grammar)– Assessment of the Environmental Performance Requirements

• Conclusions

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OVERVIEW AND SUMMARY

INDEPENDENT REVIEW - SURFACE WATER REPORT

• Large scale project; reference design.

• Three separate but interacting factors are addressed:– Water quality– Geomorphology– Flooding

• Peer review role:– Review of methodologies, results and assumptions– Identify any additional matters to address EES Scoping

Requirements, etc.– Review adequacy of proposed EPRs

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SUMMARY – WATER QUALITY

• Key issues, relevant standards and potential mitigation measures identified.

• EPRs SW1, SW2 and SW3 apply

• Expert conclave report has also suggested refinements to:– SW4 - Extension of monitoring to operations– SW5 - Construction water management plan– SW8 - Minimising impacts from waterway modifications– SW11 - WSUD and engagement with local drainage authorities*– SW12 - Fit for purpose water quality for existing land uses– SW14 - Retain or replace existing water quality treatment assets to meet

or exceed existing water quality treatment performance potential

• Confident that the EES includes sufficient information for this stage of the process and to move to detailed design with appropriate EPRs, standards and approvals processes.

* - Agreed by 3 out of 4 expert witnesses

SUMMARY – GEOMORPHOLOGY

• Key issues identified by qualified consultant

• EPR SW1 applies

• Expert conclave report suggests refinements to:– SW5 - Construction water management plan– SW8 - Minimising impacts from waterway modifications– SW9 - Maintain bank stability in consultation with local drainage

authorities– SW11 - WSUD and engagement with local drainage authorities*

• Confident that the EES includes sufficient information for this stage of the process and to move to detailed design with appropriate EPRs, standards and approvals processes.

* - Agreed by 3 out of 4 expert witnesses

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SUMMARY – FLOODING

• I am confident that the EES includes sufficient information to identify flooding issues at this stage of reference project design.

• Some changes in flooding sufficient to require mitigation are yet to be resolved, but I am satisfied there are a range of additional measures that can be considered as part of detailed design.

• The expert conclave report has suggested refinements to:– SW5 - Construction water management plan– SW6 - Minimise risk from changes to flood levels, flows and velocities

Use of ANCOLD guidelines– SW7 - Flood emergency management plans

• I am satisfied that the refined EPRs as proposed by the Expert Conclave provide sufficient controls to manage the flooding aspects of the North East Link project as it progresses to detailed design.

* - Agreed by 3 out of 4 expert witnesses

DETAILED PRESENTATION

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WATER QUALITY

• KEY ISSUES IDENTIFIED:– Spills, Construction, Road runoff– Semi-quantitative assessment using existing data– Reliance on WSUD and industry-standard MUSIC modelling for road

runoff.– Subject to SEPP (Water) and other approvals

• CONCLUSIONS:– Key issues, relevant standards and potential mitigation measures

identified.– Sufficient information to move to detailed design with EPRs,

standards and approvals processes.

WSUD - Water Sensitive Urban Design

GEOMORPHOLOGY

• Key issues identified– Qualitative assessment of streams and wetlands by

geomorphologist– Realignment of some streams and wetlands will inevitably lead to

physical and hydraulic changes.– Undergrounding of some streams segments– WSUD framework to be applied.

• CONCLUSION:

– Sufficient level of analysis to identify key issues and progress to detailed design.

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FLOOD RISK – REVIEW

• Concept level/reference design; detailed design stages to follow

• Hydrological and hydraulic modelling to identify key matters

• Focus of Review:– Scale, methods and data– Flood extent, afflux, velocities– Test mitigation options– Engagement with MWC and local government (as drainage

authorities), and– EPRs and approvals processes.

FLOOD RISK – SCALE, METHODS AND DATA

• Large scale, multiple catchments

• Hydrology – flood inflows, probabilistic– Whole-of-catchment models– Industry standard models, RORB– Australian Rainfall and Runoff 1987/2019– Range of rainfall events:

AEPs, depths, durations, patterns

• Hydraulics – flood depths & velocities– Largely limited to Project footprint– Industry standard models, TUFLOW– Reasonable approach for this stage

of assessment (reference design)

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FLOOD RISK – FOOTPRINT, METHODS AND DATA

• Hydraulics– Different model detail for different catchments– Use of local approved models– Overall a small increase in afflux; some reductions and some

increases depending on events and locations.– Some key areas for consideration at detailed design (e.g.

concentration of flows, interfaces with local drainage infrastructure).

– EPRs require on-going interaction with drainage authorities

1% AEP1: 100 AEP

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FLOOD RISK – PROPOSED MITIGATION IN EES

• Across the Project, modelling results show limited areas of increased flooding sufficient to warrant mitigation.

• For each waterway the reasons for increases in flood depth or extent were reviewed with the consultant.

• Recommended and potential alternative design options were discussed with the consultant.

• Evident that a range of design options are available at each location.

• Need to work through best option or combination of options during iterative detailed design process involving local drainage authority (MWC or local government).

RANGE OF MITIGATION SOLUTIONS

ELIMINATE:

• Reducing pavement / using permeable materials

• Diverting flows (e.g. realignment, slopes, piping)

• Deepening/widening/raising to remove flow constraints

MITIGATE:

• Retarding basins

• Under-ground storage

• Freeboard

• Swales, levees, landscaping and wetlands

MANAGE:

• Excluding people from hazardous areas

• Barriers, etc.

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INVOLVEMENT OF DRAINAGE AUTHORITIES

FLOOD RISK – RELEVANT DRAINAGE AUTHORITY INVOLVEMENT• Evidence of engagement with relevant drainage authorities.

• Use of approved local government hydraulic models.

• Local government & MWC on the Technical Panel.

• Appropriate on-going engagement is planned and intended for detailed design as per the draft EPRs in the EES.

• MWC Standards for Infrastructure Projects in Floodplain Areas and Submission 800:

‘Whilst there appears to be a number of flood issues which have not been fully resolved at this stage, these issues have been acknowledged

and will be resolved during the detailed design stage of the Project.’

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FLOODING AROUND NORTH EAST LINK PROJECT

WATERWAYS AROUND NORTH EAST LINK

Yarra River

KoonungCreek

Banyule Creek

KempstonSt Drain

Yando St Main DrainWatsonia

Drain

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1% AEP FLOOD DEPTHS – YANDO

AFFLUXCURRENT

FLOOD MITIGATION – YANDO DRAIN

• CONTEXT: Existing flooding issues, Existing 1.8m dia. culvert that is a shared use path.

• PROJECT: Wider road, no change to culvert. Reduced storage on upstream side. Impacts of project relatively small.

• MITIGATION MEASURES:– Landscaping for additional flood storage– Overpass to eliminate/mitigate flood risk– Need to work with local drainage authority

• OTHER OPTIONS CANVASSED:– Widen or deepen the underpass– Retarding basin upstream or in adjacent parkland but loss of

amenity– Retarding basin downstream.

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1% AEP FLOOD DEPTHS – KEMPSTON DRAIN

AFFLUXCURRENT

FLOOD MITIGATION – KEMPSTON DRAIN

• CONTEXT: Existing flooding issues; AK Lines Reserve retarding basin –landfill, no records; Roadways designed as drainage lines.

• PROJECT: Increased flood extent but minor afflux. Downstream flooding mainly from local runoff.

• MITIGATION:– New retarding basins + elevated pathways/cycle way– Work with local drainage authority during detailed design.

• OTHER OPTIONS CANVASSED:– Increase flood storage at AK Lines reserve.– Works on Kempston St drainage.– Additional retarding basin(s) or redirection of flows on east of

freeway.

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1% AEP FLOOD DEPTHS – WATSONIA STN DRAIN

AFFLUXCURRENT

FLOOD MITIGATION – WATSONIA STATION

• CONTEXT: Existing flooding

• PROJECT: Road widening, new carpark, road drainage. General increase in extent of flooding, but typically small depths except in vicinity of carpark. Technical Note R32 indicates an alternate design.

• MITIGATION:– Detailed design needed for new carpark and service road– Increase upstream and downstream floodplain storage– Work with local drainage authorities.

• OTHER OPTIONS CANVASSED:– Carpark - culverts, elevated carriageway, multiple egress points,

underground storage.– Upstream storage in parklands, methods to direct or manage

shallow flows.

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1% AEP FLOOD DEPTHS – BANYULE CREEK

AFFLUXCURRENT

FLOOD MITIGATION – BANYULE CREEK

• CONTEXT: Existing flooding

• PROJECT: General increase in extent of flooding, typically small depths but some significant rises. Diversion of Banyule creek to drainage. Storage ponds near Plenty Road. Alternate design for Lower Plenty Road interchange as per Technical Note R33.

• MITIGATION: – Need for careful detailed design particularly reconsidering layout– Considerable rationalisation potential– Need to work with local drainage authority during detailed design

• OTHER OPTIONS CANVASSED:– Reconsider pavement layout/alignment– Floodplain storage– Road camber and diversion of flows away from Banyule Creek

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1% AEP FLOOD DEPTHS – YARRA RIVER

AFFLUXCURRENT

FLOOD MITIGATION – YARRA RIVER

• CONTEXT: Existing Yarra River ponded floodplain area.

• PROJECT: Discharge of road runoff and engineering works into floodplain affect flood storage and lead to 1 – 22mm flood afflux over existing deep flood waters. Alternate Bulleen Rd design for review (Tech Note R34).

• MITIGATION: – Afflux upstream of bridge mitigated by Manningham Road design.– Flood walls near southern portal reduce flood storage but need to

be optimised whilst appropriately protecting the portal.

• OTHER OPTIONS CANVASSED:– Detailed design to maximise use of pre-development flood storage

and not impede conveyance.– Use of upstream flood storage.– Local works.

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1% AEP FLOOD DEPTHS – KOONUNG CREEK

AFFLUXCURRENT

1% AEP FLOOD DEPTHS – KOONUNG CREEK

AFFLUXCURRENT

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FLOOD MITIGATION – KOONUNG CREEK

• CONTEXT: Existing flooding. Constrained footprint.

• PROJECT: Road widening, realignment and increased undergrounding (1100 – 1400m) of creek. Reduction or no change in flood depths. Design of roadway and interaction with WSUD and flood mitigation measures is critical.

• MITIGATION:– Range of WSUD elements and flood barriers, etc.– Significant work still required to maximise the use of flood storage

above or under ground and volume transfer. – Work with local drainage authorities

• OTHER OPTIONS CANVASSED:– Realignment of works to manage flows– Minimising undergrounding of creek– Maximise use of flood storage

RESPONSE TO KEY SUBMISSIONS

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RESPONSE TO KEY SUBMISSIONS

• Key submissions raised a number of issues that I have responded to in my Expert Witness Report.– Additional information on flood modelling– Flood impacts on private property and existing infrastructure– Water sensitive urban design and water quality– Impacts on Bolin Bolin Billabong– Undergrounding of Koonung Creek– Safe operation of the southern tunnel portal

• Many of these matters also arose at the Expert Conclave and are addressed in the refined EPRs recommended by the report as discussed shortly.

• I have provided additional information on Bolin Bolin, Koonung Creek and the southern tunnel portal in the following slides.

RESPONSE TO KEY SUBMISSIONSBolin Bolin Billabong

• There may be opportunities from the Project to improve the condition of Bolin Bolin billabong (Submissions Melbourne Water Corporation #800, Parks Victoria #774 and EPA Victoria #600).

• It is my experience that specific designs are required to achieve improvements from environmental watering projects. This requires a multi-disciplinary approach.

• Whilst there may be changes in groundwater levels, there are potential options for the direct or indirect use of stormwater runoff to improve the condition of Bolin Bolin.

• The following slides indicate how wetlands are topped up by flood flows and appropriate management of Yarra River inflows may be a complementary option for improvement of Bolin Bolin.

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FLOODPLAINS – DEFINITION AND FUNCTIONS

• Typically low relief areas adjacent to rivers and streams

• Storage and conveyance of floodwaters

• Range of functions - depositional areas for nutrients and soils, groundwater recharge, and support for wetlands and riparian habitats

Floodway

Flood FringeFlood Fringe

Fill

Wetland

FLOODPLAINS – HOW THEY WORK UNDER FLOOD

• Direct watering of wetlands and riparian vegetation

• Infiltration into soil profile and groundwater

• Sediment deposition

• Flood storage/conveyance affected by fill or structures

Floodway

Flood FringeFlood Fringe

Fill

Wetland

Deposition

Infiltration FloodingGroundwater

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RESPONSE TO KEY SUBMISSIONSUndergrounding of Koonung Creek

• I have discussed the current poor ecological condition, limited existing fish populations, and undergrounding of Koonung Creek with environmental consultants who prepared Chapter 25.

• My understanding is that the current undergrounded section is ~1100m long.

• The Reference Project seeks to increase this length to ~1400m.

• In other words, there is a large section of the Creek that is already underground and this would provide a barrier to some species.

• I further understand that detailed design will look to minimise undergrounding where possible.

RESPONSE TO KEY SUBMISSIONSSafe operation of the southern portal

• Infrastructure such as roads need to be designed to achieve a required level of service. That is, to be able to be used as planned.

• Owners generally default to flood standards or make a deliberate design decision regarding the acceptable risk for their infrastructure.

• In some situations it is necessary to implement structural and/or non-structural flood mitigation measures to reduce public risks.

• For tunnel portals flood gates, drop logs or other active measures are often used. But the preference is for passive measures as outlined in the EES.

• A portal flood management plan is required.Flood gates and other mitigation measures are widely used; often

coupled with warning systems(e.g. SMART Tunnel Kuala Lumpur).

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CONCLAVE REPORT

CONCLAVE REPORT – REFINEMENT OF EPRS

• High level of agreement

• Recommended EPR refinements.

• Discussed MWC and EPA Vic proposed amendments

• Reviewed and agreed with the following proposed EPRs:– SW1, SW2, SW3, SW7, SW10 and SW13.

• Discussed and agreed additional refinements and amendments to the following EPRs:– SW4, SW5, SW6, SW8, SW9, SW12 and SW14.

• The effect of the proposed changes provides reasonable additional clarification and requirements on the Project.

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CONCLAVE REPORT – REFINEMENT OF EPRS

• The following EPR was agreed by three of the Conclave members, but not the fourth:– SW11 (Water Sensitive Urban and Road Design)

• The reasons for disagreement are outlined in the expert report and summarised below:– Encourage the Project to meet standards above current water

quality– Potential for the decline in water quality if using BPEMG– Insufficient information in the EES to confirm BPEMG will result in

improvements in water quality

• Four matters beyond surface water that could have an impact on EPRs or process were also reported to the IAC.

Changes in guidelines and policies

• The conclave members are aware of a number of guidelines that are in draft form or may emerge during the Project (e.g. Environment Protection Act).

• The conclave asked the IAC to consider a requirement that allows for the use of the latest guidelines in consultation with the relevant regulatory authority.

• It is thought this might already be covered by due process.

CONCLAVE REPORT – OTHER MATTERS

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Asset design, maintenance, and transfer

• WSUD asset maintenance is important to ensure it continues to perform according to its design objectives.

• Examples of major project assets not being maintained were cited.

• The regulation of WSUD assets is unclear.

• Some local councils have preferences for different types of WSUD assets and may be unwilling to take on the responsibility for certain asset types.

• The proposed ownership and transfer of WSUD assets is unclear.

• It would be useful for the involvement of the ultimate asset owners in the design process with the aim of reaching agreement on the transfer and maintenance of assets in the longer term.

CONCLAVE REPORT – OTHER MATTERS

Monitoring and review of assets

• The conclave was unclear on the intended arrangements for on-going monitoring and review of Project performance during operations.

• This is considered an important issue to ensure assets are maintained and perform in accordance with design objectives.

• Recommended that the IAC consider the arrangements for on-going monitoring and review of WSUD assets and other relevant assets associated with the Project.

CONCLAVE REPORT – OTHER MATTERS

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Integrated Water Resource Management

• A WSUD-only focus could miss opportunities to address beneficial amenity and environmental values.

• Conclave recommended IAC give due consideration to:– Integration of WSUD, Urban Design Strategy, etc.– Process of developing and implementing this plan.

CONCLAVE REPORT – OTHER MATTERS

REPORTS BY MR CAWOOD

• On 31 July 2019, I received a report by Mr Cawood dated 15 July 2019 regarding the potential impact of the project on Carey Baptist Grammar School.

• It was acknowledged that variations from the Reference Design have yet to be incorporated in modelling along with other matters of relevance to the Bulleen campus.

• Acknowledged flood impacts are unlikely to be substantial.

• Noted that results from additional modelling of Koonung Creek post Reference design may be beneficial, but unseen.

• Requested a change to EPR SW6 to ensure the Bulleen Campus’ critical levels and areas be incorporated in modelling to assess the impact on Carey.

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REPORTS BY MR CAWOOD

• Mr Cawood’s report was in addition to a report dated 20 May 2019.

• In that report Mr Cawood noted the use of 1% AEP flood modelling in the EES rather than a broader range of floods.

• Insufficient information to assess the exact impact on Carey Baptist Grammar School.

• I believe Mr Cawood’s assessment is understandable at the Reference design stage.

• More detailed modelling of Project configurations will be required before the exact impact of the Project on the Bulleen campus can be fully quantified. This is expected to occur during detailed design.

ASSESSMENT OF THE ENVIRONMENTAL PERFORMANCE REQUIREMENTS

• In my view EPRs: SW1, SW2, SW3, SW4, SW5, SW6, SW7, SW8, SW9, SW10, SW12, SW13 and SW14 as agreed to be amended by the Surface Water Conclave; together with the proposed amendment to SW11 and EPRs B3 and CL5 are appropriate and will ensure that the environmental effects of the Project relevant to surface water can be suitable managed.

• I note that the following EPRs: B5, CL1, CL5 & CL6, FF4, FF6, FF9, GW1,GW2, LP1, LP2, LP3, complement the surface water EPRs by providing for the protection of existing utility assets, management of spoil and maintenance of ground cover, management of hazardous chemicals, and other matters of relevance to surface water and flood management.

• I do not recommend any further changes to the EPRs for the Project.Notes:

B3 - Minimise and remedy damage or impacts on third party property and infrastructureCL5 - Manage chemicals, fuels and hazardous materials

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CONCLUSION

• I am satisfied that the EES includes sufficient information to identify relevant water quality, geomorphology and flood issues at this stage of design.

• I am satisfied that the amended EPRs as proposed by the Expert Conclave provide sufficient controls to manage the water quality, geomorphology and flooding aspects of the North East Link project.