North East Link Inquiry and Advisory Committee Expert Witness Statement of David Fuller
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North East Link Inquiry and Advisory Committee Expert Witness Statement of David Fuller 1 Introduction 1.1 I undertook a peer review of the Surface water technical report for the North East Link (Project). This peer review report is contained in Technical Report P - Surface Water in the Environmental Effects Statement (Technical Report) at Appendix G and is dated 4 March 2019 (Peer Review Report). 1.2 I have been instructed by Clayton Utz on behalf of NELP to review and respond to the public submissions and give evidence on the environmental effects of the Project relevant to my area of expertise. 2 Qualifications and experience 2.1 Annexure A contains a statement setting out my qualifications and experience, and the other matters raised by Planning Panels Victoria’s Guide to Expert Evidence. A copy of my curriculum vitae is provided as Annexure B. 3 Peer Review 3.1 As Peer Reviewer I was engaged during the preparation of the EES to review water quality, geomorphology and flood estimation methodologies and conclusions as presented in the Surface Water technical report. This included the assessment of the pre- to post- project changes in flooding, but not the engineering designs – a subject that I am familiar with but is outside my specific areas of expertise. 3.2 I engaged in discussions with technical personnel who had contributed to the report regarding the assumptions made, the conclusions reached, the approaches taken, and the standards, data and calibration methods used. 3.3 A number of versions of the draft surface water report were provided for review during the course of the development of the EES. The authors addressed peer review comments on the reports during each round of this process. 3.4 I adopt the Peer Review Report, in combination with this statement, as my written expert evidence for the purposes of the North East Link Inquiry and Advisory Committee’s inquiry into the environmental effects of the Project. 4 Further work since preparation of the Peer Review Report 4.1 Since the Peer Review Report was finalised, I have undertaken further review of a Technical Memorandum titled ARR 2016 Sensitivity Assessment – Watsonia Station drain, Banyule Creek and Koonung Creek models dated 15 July 2019. This Memorandum is included in Annex C to this report. 4.2 A summary of my findings in relation to this further work is: • Unsurprisingly, the application of the latest national guidelines for flood estimation provided in Australian Rainfall and Runoff (ARR) 2019 compared with ARR 1987 led to some differences in the estimates of pre-development flood level depths, velocities and extents. • In some cases pre-development flood depths estimated using ARR 2019 are less than those estimated using ARR 1987. In some cases the opposite is true. 1 of 28 North East Link Inquiry and Advisory Committee Expert Witness Statement of David Fuller • It is noted by the authors that the application of a constant “continuing loss rate” (a hydrological model parameter) as recommended in ARR 2019 compared with reducing continuing loss rates recommended in ARR 1987 results in lower extreme flood estimates than the earlier guidelines. This is despite an increase in rainfall intensity compared with the earlier guidelines. • In most cases the differences in modelled flood levels, extents and velocities are not substantial between the two methodologies and are within the level of modelling accuracy. • The models are constrained by the lack of observed local data. Consequently recommended default parameters are utilised to generate model results. These default parameters have been developed based on experience in the modelling of flood inundation over many studies in urban areas so they provide a level of confidence that the comparison between pre- development and post-development change is appropriate. • However, the absolute modelled water levels are subject to error in which case engineers should take this into account and adopt appropriate freeboard in their engineering designs. • At a few locations there are substantial differences in pre-development modelled flood levels between the two methodologies. These locations appear to be near model boundaries or near significant flow constraints such as existing embankments, underpasses or culverts. The authors of the Technical Memorandum suggest that these anomalous results are generally due to modelling assumptions (e.g. boundary conditions). • It is important to note that Melbourne Water Corporation has now adopted ARR 2019 as its standard methodology for the assessment of pre-development to post-development changes in flooding. Substantive changes in flood inundation or frequency are not permitted as recognised in EPR SW6. • As a consequence, it is my understanding that project approval will be dependent on the adoption of EPR SW6 that required amelioration of any substantive change in pre- development to post-development flood risk based on the final configuration and design of the North East Link. • The results presented in the Technical Memorandum do not alter the types of infrastructure, design constraints or conditions required for amelioration of changes in flooding. • However, the results do indicate that significant care is required to examine, and where possible confirm, some the localised flooding as part of detailed design. Where necessary, appropriate additional freeboard should be incorporated in the detailed design to account for uncertainty. 4.3 Since the Peer Review Report was finalised, I have also been requested to read the EES and consider the potential implications of changes in hydrology and water quality on the environment and any other matters that I consider that I could reasonably comment upon. 4.4 This further work has not caused me to materially change my opinions as expressed in the Peer Review Report. 2 of 28 North East Link Inquiry and Advisory Committee Expert Witness Statement of David Fuller 5 Summary of key issues, opinions and recommendations Key issues identified in this Statement are: • A need for more detailed information regarding the design of the works and mitigation of flood risk. • Potential flood impacts on private property or existing infrastructure • Safety and operation of the southern portal design • Integrated water management and Water Sensitive Urban Design (WSUD) • Water quality impacts during construction I am satisfied that the EPRs are sufficient to account for each of these matters. Submissions on minor proposed amendments to the EPRs appear appropriate as they seek to clarify the intent and/or involvement of regulators and other relevant parties; or seek to extend monitoring of Project performance to operations. 6 Submissions Submissions received 6.1 I have read the public submissions to the EES, draft planning scheme amendment and works approval application and identified those that are relevant to the Technical Report and my area of expertise. These include the following submissions: 25, 40, 47, 82, 88, 100, 112, 113, 145, 208, 237, 274, 290, 312, 316, 340, 375, 396, 411, 415, 446, 512, 514, 516, 519, 520, 522, 526, 533, 534, 539, 552, 556, 563, 598, 600, 601, 611, 617, 634, 645, 646, 657, 666, 669, 694, 700, 703, 714, 715, 716, 717, 725, 742, 774, 777, 783, 793, 800, 802, 803, 820, 826, 848, 857 Summary of issues raised 6.2 The submissions have raised the following issues relevant to my area of expertise: a) Additional information required on the detail of flood modelling results or approaches b) Potential flood impacts of the Project on private property c) Amelioration of existing stormwater flooding of properties (Bulleen & Banyule Creek) d) Impacts on local flooding arising from changes to existing retarding basins or other infrastructure e) The need to account for impacts on significant water infrastructure including stormwater, sewerage and recycled water assets and functionality. f) The safety and operation of the southern tunnel portal in the floodplain g) The need for integrated water management planning and Water Sensitive Urban Design h) Increased stormwater runoff and associated water quality impacts i) Lack of information on changes in local hydrology and consequent impacts on aquatic ecosystems including wetlands j) The impacts of isolating the Banyule Creek headwaters k) Impacts on Koonung Creek and other waterways l) The potential for water quality impacts during construction 3 of 28 North East Link Inquiry and Advisory Committee Expert Witness Statement of David Fuller In addition to the Peer Review process I have read relevant sections of the EES and am answering questions to the best of my ability. Most of my responses are submitted as comments regarding ways in which the issues raised might be addressed recognising that in my opinion the EPRs are generally sufficient to accommodate effective design decisions to ameliorate flood impacts provided they are appropriately implemented and monitored. I also recognise that there is on-going involvement of regulatory and approvals agencies such as Melbourne Water and Vic EPA on many of these matters; and there are future stages of more detailed engineering design planned for the Project. Response to issues raised 6.3 Set out below are my comments and responses to the issues raised by the written submissions relevant to the area of my expertise. 6.4 Additional information required on the detail of flood modelling results or approaches [Issue a)]. The City of Manningham has raised the need for involvement and scrutiny of hydraulic modelling results to ensure effective integration