Expert Witness Statement of Robert Campbell Swan

Transcription

1 Expert Witness Statement of Robert Campbell Swan Manningham Planning Scheme Amendment C109 V Prepared for Planning Panels Victoria 29 January January 2018 Cardno i

2 Contact Information Document Information Cardno Victoria Pty Ltd ABN Level Swanston Street Melbourne 3000 Australia Prepared for Project Name File Reference Job Reference Planning Panels Victoria Manningham Planning Scheme Amendment C109 Document1 V Phone Fax Date 29 January 2018 Version Number 1 Cardno. Copyright in the whole and every part of this document belongs to Cardno and may not be used, sold, transferred, copied or reproduced in whole or in part in any manner or form or in or on any media to any person other than by agreement with Cardno. This document is produced by Cardno solely for the benefit and use by the client in accordance with the terms of the engagement. Cardno does not and shall not assume any responsibility or liability whatsoever to any third party arising out of any use or reliance by any third party on the content of this document. V January 2018 Commercial in Confidence ii

3 Table of Contents 1 Name and address 1 2 Position 1 3 Area of expertise 1 4 Glossary of Terms 2 5 Services 4 6 Preparation of Flood Overlays Criteria 1: Properties adjacent to flooded roads Removal of Council Flood Extents 7 7 Response to Submissions 10 8 Final Comments 12 9 Declaration 12 Annexures Annexure A CV of Robert Campbell Swan Annexure B December 2017 SBO and LSIO Extents Annexure C Melbourne Water - Finalising Flood Extentsfor Inclusion in Planning Schemes Annexure D Submission Assessment Tables Table 7-1 Review of Submissions Summary 10 Figures Figure 6-1 Neighbouring Cells 5 Figure 6-2 Trimming of Flood Extent along Roads 6 Figure 6-3 Critical Duration Analysis Example. 8 Figure 6-4 Proximity to Melbourne Water assets example 9 Figure 6-5 Manual Inspection Trimming example 9 V January 2018 Commercial in Confidence iii

4 1 Name and address Mr Robert Campbell Swan Cardno Victoria Pty Ltd Level 4, 501 Swanston Street Melbourne, VIC Position Principal Engineer, Hydrology and Hydraulics Manager, Water Engineering Cardno 3 Area of expertise a. My area of expertise is hydrology and hydraulics, particularly the areas relating to the flow and characteristics of surface water and flood dynamics. b. I was the Project Manager and technical lead for the Bulleen North Flood Mapping project, undertaken on behalf of the City of Manningham and Melbourne Water. c. I was the Project Director and technical lead for the Mullum Mullum Creek, Koonung Creek, Andersons Creek Flood Mapping projects, undertaken on behalf of the City of Manningham. d. I assisted the City of Manningham and Melbourne Water in the development of the proposed LSIO and SBO extents for Amendment C109. e. I am a member of the Victorian State Emergency Service expert hydrology panel to provide flood advice and analysis during flood related emergencies. f. My qualifications are detailed in Appendix A. V January 2018 Commercial in Confidence 1

5 4 Glossary of Terms Average Exceedance Probability (AEP) The chance of a given discharge or level value being exceeded in a given year. A 1% AEP flood event has a 1% chance of occurring in any year (and is equivalent to the 1 in 100 year ARI event). The conversion from ARI to AEP is shown in the table below ARI (years) AEP (%) 1 63% 2 39% 5 18% (usually approximated as the 20% AEP) 10 10% 20 5% 50 2% 100 1% Australian Height Datum (AHD) Average Recurrence Interval (ARI) Catchment City of Manningham (MCC) Design flood DELWP Difference Plot Discharge Floodplain Hydraulics Hydrograph Hydrology A common national surface level datum approximately corresponding to mean sea level. The average or expected value of the period between exceedances of a given discharge or event. A 100-year ARI event would occur, on average, once every 100-years. The area draining to a site. It always relates to a particular location and may include the catchments of tributary streams as well as the main stream. The City of Manningham is the local government authority for Amendment C109 A significant event to be considered in the design process; various works within the floodplain may have different design events. e.g. some roads may be designed to be overtopped in the 1 in 1 year or 100%AEP flood event. The Department of Environment, Land, Water and Planning of the Victorian Government A map showing the difference in flood depth between two flood events. The rate of flow of water measured in terms of volume over time. It is to be distinguished from the speed or velocity of flow, which is a measure of how fast the water is moving rather than how much is moving. Area of land which is subject to inundation by floods up to the probable maximum flood event, i.e. flood prone land. The term given to the study of water flow in a river, floodplain, channel or pipe, in particular, the evaluation of flow parameters such as stage and velocity. A graph that shows how the discharge changes with time at any particular location. The term given to the study of the rainfall and runoff process as it relates to the derivation of hydrographs for given floods. V January 2018 Commercial in Confidence 2

6 Mathematical/computer models Melbourne Water Corporation (MWC) Risk Runoff Topography The mathematical representation of the physical processes involved in runoff and stream flow. These models are often run on computers due to the complexity of the mathematical relationships. In this report, the models referred to are mainly involved with rainfall, runoff, pipe and overland stream flow. Melbourne Water is the regional floodplain management authority for the Melbourne Metropolitan area. Melbourne Water generally controls flooding once catchment area reaches greater than 60 hectares Chance of something happening that will have an impact. It is measured in terms of consequences and likelihood. For this document, it is the likelihood of consequences arising from the interaction of floods, communities and the environment. The amount of rainfall that actually ends up as stream or pipe flow, also known as rainfall excess. A surface which defines the ground level of a chosen area. V January 2018 Commercial in Confidence 3

7 5 Services My services were engaged to provide expert opinion on issues relating to the derivation and assessment of the flood related overlays in the City of Manningham. My instructions were: 1 Prepare an expert report detailing the derivation of the proposed flood shape for the proposed amendment; 2 Provide an independent review of submissions relating to flooding in the proposed SBO and LSIO area 3 Respond to the 44 submissions, including 35 directed to Melbourne Water, plus 9 additional late submissions received by Melbourne Water. My evidence does not include any comment on the impact of flooding on property values or insurance premiums. 6 Preparation of Flood Overlays I supervised the initial preparation of the flood related overlays for Amendment C109. Theses shapes are derived from flood modelling undertaken from 2009 onwards for the City of Manningham. I consider the flood modelling to be suitable for the derivation of flood planning overlays. The flood modelling projects were: > Bulleen North Flood Mapping Project, completed by Cardno for Melbourne Water, in conjunction with the City of Manningham > Mullum Mullum Creek Flood Mapping Project, completed by Cardno for the City of Manningham, in conjunction with Melbourne Water > Andersons Creek Flood Mapping Project, completed by Cardno for the City of Manningham, in conjunction with Melbourne Water > Koonung Creek Flood Mapping Project, completed by Cardno for the City of Manningham, in conjunction with Melbourne Water > Ruffey Creek Floodplain Mapping, completed by AECOM for Melbourne Water, in conjunction with the City of Manningham Each of these projects was completed generally in accordance with the Melbourne Water s relevant Technical Specifications for Flood Mapping Projects that were relevant at the time of project commencement. The projects completed by Cardno adopted the direct rainfall method for hydrological analysis, and this approach was tested during the Bulleen North project and accepted by Melbourne Water. Water Technology P/L has also completed an independent technical review of the methodology. The direct rainfall approach is considered suitable for urban flood mapping projects in the latest version of Australian Rainfall and Runoff (2016). The methodology adopted for these flood mapping projects allowed for identification of flooding associated with both Council and Melbourne Water assets. Initial flood shapes for Amendment C109 were developed on this basis. It is my understanding that the proposed overlay now only considers flooding associated with Melbourne Water assets, these being main drains, creeks and rivers. The aim of the proposed planning extents are to identify areas that require planning controls to ensure appropriate responses to flooding. It is not necessary to have a flood related control in all areas where overland flows occur or are predicted by a flood model. For the Amendment C109, significant analysis was undertaken to develop the overlays to capture areas considered as flood prone. The derivation of the planning flood extents was completed by processing the model results from each flood study to the same criteria, based on Melbourne Water 2013/14 Flood Mapping Technical Specification. To develop the initial flood overlay shapes, a number of inclusion and exclusion criteria were adopted. Initially, flooded areas were identified using a filtering approach on the results of the flood models. The flood models report results on a gridded basis, providing a flood level and expected velocity for at a resolution of 3m*3m V January 2018 Commercial in Confidence 4

8 across the entire city of Manningham. This is output as a grid of results from the flood model, spatially distributed according to location. The filters adopted for this project were as per Melbourne Water Technical Specifications for flood mapping. In my experience, the use of such filters is standard practice. These filters remove areas identified in the flood mapping as having very shallow flood depths or very low velocity by depth products (a measure of flood risk). The initial filtering aims to provide baseline or raw data suitable for further analysis and a reasonable estimate of areas where flows have consolidated to form an overland flow path. The initial filtering parameters removed from consideration grid cells where: > the depth of flooding was less than 0.05m and the velocity by depth product was less than m 3 /s Once this was completed, the data was flattened to generate a preliminary flood extent. This extent ensures that neighbouring cells were connected where they touch. Figure 6-1 shows all cells considered as neighbours and includes diagonal connections. Figure 6-1 Neighbouring Cells This flattened shape contains a number of polygons that represent the spatial area that is flood affected. Additional filtering is then completed to areas known as wet islands or dry islands. A wet island is a small area of land that is flooded, surrounded by areas considered not to be flooded. A dry island is a small area of land not considered flooded, surrounded by flooded land. In the preliminary flood extents developed for Amendment C109, the threshold adopted was 100 m 2. Dry islands were removed and considered flooded and wet islands were removed and considered not subject to flooding. In my experience, this approach allows for the identification of relevant flow paths and generates flood shapes that are generally suitable for floodplain management purposes. For Amendment C109, these initial shapes underwent additional refinement to provide overlays that appropriately responded to the flood risk. For example, if a small area of a property was flooded, it may be appropriate to exclude it from the planning overlay. A number of criteria were developed to assess if an area should be included in the proposed overlays. I have described the initial criteria in the following sections. It should be noted that these criteria were specifically developed to be relevant to flood shapes that cover the entire catchment. At the time of the development of the overlays, there were no specific guidelines on how to produce a final flood planning shape. A number of meetings and workshops were held between Cardno, Melbourne Water and Council to determine how the planning flood shape would be developed. The criteria adopted are described in sections These criteria were developed such that they were similar to those used by Melbourne Water across other municipalities Criteria 1: Properties adjacent to flooded roads There are many areas in Manningham where flooding is generally contained within the road reserve, however, due to the flood mapping methodology, the flood extents generated from the flood model results may encroach slightly onto properties. This criteria identifies and removes areas from the proposed planning extent on properties where this occurs, as shown in Figure 6-2. The guidelines adopted for this criteria were: Removed from SBO: If the flooded area of a property was entirely within 5 m of a roadway and the percentage of the property affected was less than 10%. Retained as part of SBO: If other areas of the property, not within 5m of the roadway, were flood affected. V January 2018 Commercial in Confidence 5

9 Figure 6-2 Trimming of Flood Extent along Roads Criteria 2: Isolated ponding The flood modelling approach used identifies all potential flowpaths in a catchment, including those that may be unrelated to drainage infrastructure. These could be on larger properties, upstream of the drainage network or isolated low points within individual properties. Guidelines were adopted to account for these areas: Removed from the SBO: If flooded area was less than 500 m 2, fully disconnected from the flood extent and situated away from the underground drainage network. Removed from the SBO: Either if: a) The flooded area was disconnected from the flood extent, the drainage network, had a maximum flood depth less than 200 mm and the raw (unfiltered) data did not suggest connection to the neighbouring flood extent. These areas were usually isolated local depressions on the land surface b) The area was less than 500 m 2, the maximum flood depth was less than 200 mm and the raw (unfiltered) data did not suggest connection to the neighbouring flood extent. Removed from the SBO: If the flooded area was determined to be a body of water such as a swimming pool, but not an online dam or similar water storage Criteria 3: Connecting Disconnected Extents The flood extents produced by the flood mapping projects have been filtered to remove areas that do not meet specified criteria. In some cases this can lead to a visual disconnection in the planning extent that can appear to show flooded areas with no logical connections. This result can be due to the connected flows being less than 50mm in depth such that the connection is not fully mapped. The proposed planning extents have been amended to provide a more continuous flood extent in these cases. Connections Made: If the flood extent in the raw (unfiltered) model outputs suggested a connection could occur, and no additional properties are impacted by the change. V January 2018 Commercial in Confidence 6

10 6.1.5 Criteria 4: Differentiating between LSIO and SBO 1 Areas designated as LSIO and SBO are both Melbourne Water controlled. This delineation is applied at a catchment scale so as not to interchange between each scheme along the same flow path. The guidelines for delineation are: LSIO: If flooding is present along a mainstream flow path (e.g. creek, river, etc.). SBO: If flooding is present along a Melbourne Water underground asset. 6.2 Removal of Council Flood Extents It is my understanding that flood extents associated with council owned assets are no longer included in the proposed SBO for Amendment C109. As part of the initial analysis, the SBO areas were split on a property basis into areas that would be responded to by Melbourne Water and areas that would be responded to by Council. These location of this break was developed using the following guidelines: > The breaks between proposed planning extents should be along land parcel boundaries unless otherwise advised; > To avoid ambiguity, a parcel is classified as being within Melbourne Water s (MW) flood extent or Council s. This ensures that when a request for a flood level for a particular parcel is made, only one authority provides the level. > The Melbourne Water Areas occur where the flood extent is directly associated with a MW asset, including where it breaks away from the asset. > Council controlled areas begin at the top of the catchment and end once they intersect with the MW flood extent. > Where the flood extent traverses a group of units, the entire extent will be classified as one authority s flood extent based on the downstream control, unless a suitable other delineation exists. > For large parcels (schools, reserves, golf courses, etc.), the entire extent will be classified as one authority s flood extent. In the event that the parcel is subdivided in the future, both authorities will rearrange the flood extents if necessary. With the removal of Council areas from the proposed SBO, some modifications had to be made to the Melbourne Water controlled flood extent. This was done to ensure that the allocation of parcel based extents did not unfairly include areas on properties that had flooding associated with Council drainage and Melbourne Water drainage on the same parcel. The flood shapes initially exhibited as SBO1 and LSIO were refined to ensure that only flooding directly associated with Melbourne Water s drainage network were included. This was completed using three processes under my supervision, described in the following sections: Assessment of the critical storm duration The critical storm duration is a concept that provides for the maximum depth of flooding on a piece of land. The intensity of rainfall is higher in a shorter duration storm, although the total rainfall depth is lower for an AEP event. Smaller catchments therefore tend to have a critical storm duration that is shorter than larger catchments. As the models have run multiple design storm durations, we can use this information to determine where flooding is associated main drainage flows and where it is associated with surface or small catchment flows. In Figure 6-3, the Melbourne Water Main Drain has a critical duration of 60 minutes in the 1% AEP flood event. The Council drainage has a critical duration of 15 minutes. The proposed overlay excludes those areas. V January 2018 Commercial in Confidence 7

11 Figure 6-3 Critical Duration Analysis Example Proximity to the Melbourne Water Assets LSIO and SBO1 overlays show areas of flooding which occur due to Melbourne Water assets. Some flood overlays were extended beyond the asset due to one overlay type per property. In Figure 6-4, the Melbourne Water waterway does not traverse the full length of the property, whilst the proposed flood extent, associated with the gully line, does. The area that is not directly adjacent to the designated waterway was removed from the LSIO or SBO extent as appropriate as this is considered as not flooded by Melbourne Water controlled assets. V January 2018 Commercial in Confidence 8

12 Figure 6-4 Proximity to Melbourne Water assets example Manual Inspection of Water Level Where a significant flow path joins the Melbourne Water overlay, water levels were checked to determine if the overlay was caused by the Melbourne Water flow path or by the upstream catchment. When the water level started rising away from the Melbourne Water waterway, the overlay was trimmed. In Figure 6-5, the water levels along the area to be removed rose rapidly upstream from the main drain floodplain. This area was removed from the proposed overlay. Figure 6-5 Manual Inspection Trimming example V January 2018 Commercial in Confidence 9

13 Additional to the three methods described above, a number of small changes were made as a result of individual submissions to Council. These changes primarily related to land form changes that occurred after the flood modelling was initiated but prior to the results being adopted. In my experience, this is not unusual, given the lag time between the data collection for the modelling and the finalisation of the model results. Annexure B shows the proposed flood overlays after the completion of the processes described above. 7 Response to Submissions I have prepared response to the 43 submissions received by Melbourne Water with regard to their flood risk and the implications for floodplain management. In general, I have used the guidance provided in Melbourne Water s 2017 document titled Finalising Flood Extents for Inclusion in Planning Schemes, forming part of the 2017/18 Flood Mapping Technical Specification to identify if an individual submitter should be included. The relevant section of that document is attached as Annexure C, and is used to ensure a consistency of approach across all properties in the Melbourne area. Inclusion in the flood shape does indicates that on balance, I believe that application of the planning control is warranted. I am also considering the stated purpose of the SBO and LSIO in the Manningham Planning Scheme, specifically the requirement to identify areas liable to inundation. My response is based on the revised SBO Maps provided to Melbourne Water by Cardno in late December 2017, incorporating the modifications described in Section 6 of my witness statement. A map of the proposed overlay shapes used for my assessment is found in Annexure B. I have summarised the outcome of my assessment in Table 7-1. In that table, the outcome of the reviews are described as either: > Abandon Remove the proposed SBO/LSIO from the property (this would retain any existing LSIO/SBO on the property) > Retain Retain the property in the SBO/LSIO and with amendments to the shape as per the December 2017 update to remove flooding associated with the Council drainage network, as shown in Annexure D Table 7-1 Review of Submissions Summary Submission Address Suburb Outcome Number 37 4 Birchgrove Crescent Templestowe Abandon 46 Mullum Creek Estate Donvale Abandon Montpellier Crescent Templestowe Lower Abandon 71 8 Chaim Court Donvale Abandon Dehnert Street Doncaster East Abandon 96 6 Hillcroft Drive Templestowe Abandon Hillcroft Drive Templestowe Retain Hillcroft Drive Templestowe Retain Nottingwood Street Doncaster East Abandon Mossy Creek Slope Warrandyte Abandon Montclair Court Templestowe Abandon Trudi Court Donvale Abandon Lynnwood Parade Templestowe Lower Abandon Montclair Court Templestowe Abandon Hillcroft Drive Templestowe Retain Amberwood Court Templestowe Abandon Hillcroft Drive Templestowe Retain Dilkara Court Doncaster East Abandon Montclair Court Templestowe Abandon V January 2018 Commercial in Confidence 10

14 Submission Address Suburb Outcome Number Raymond Elliot Court Park Orchards Abandon Hillcroft Drive Templestowe Retain Eumeralla Avenue Templestowe Lower Abandon Hillcroft Drive Templestowe Retain and Ennismore Crescent Park Orchards Abandon 427A Mossdale Court and Greenridge Avenue (multiple properties) Templestowe Harris Gully Road Warrandyte Abandon Harris Gully Road Warrandyte Retain Hillcroft Drive Templestowe Retain Windella Quadrant Doncaster Abandon Chaim Court Donvale Abandon Tills Drive Warrandyte Abandon McGowans Road Donvale Retain Hillcroft Drive Templestowe Retain Jolen Court Donvale Abandon Aquarius Court Donvale Retain Mopoke Hill Road Warrandyte Abandon Mopoke Hill Road Warrandyte Abandon Mopoke Hill Road Warrandyte Retain Mopoke Hill Road Warrandyte Retain Mopoke Hill Road Warrandyte Retain Baradine Terrace Donvale Abandon Not Given 20 Russell Street Bulleen Retain Retain and Abandon (property dependent) At the Mullum Creek Estate, the proposed new overlay is slightly reduced compared to the existing LSIO on that property. As the change in flood extent is small, the proposed LSIO can be abandoned on this site, provided the existing LSIO is not amended. There were a number of submission that referenced multiple properties. These proposed changes to other properties are included in the individual assessments. V January 2018 Commercial in Confidence 11

15 8 Final Comments I have assessed the derivation of the proposed overlays and individually assessed the 44 submissions requested by Melbourne Water. As a result, I can advise the Panel that: > The process to derive both the preliminary flood extents and revised flood extents is consistent with those used in other areas across Melbourne > The decision by Council to not include flooding from Council drainage assets has changed the proposed SBO shape from that initially exhibited. The effect of this decision significantly reduces the extent of flooding covered by the SBO > There are known areas of flooding that are not included in the SBO that are associated with Council drainage networks. > The majority of submissions have had the flood extent either removed or amended on their property from that initially exhibited, due to the changes described in Section 6 of my evidence. This is because these properties are at the interface between Council and Melbourne Water flooding. > The areas shown in Annexure B are expected to be inundated in a 1% AEP flood event. > The proposed amendments at individual properties as per Annexure C should be included in the final overlay shape. 9 Declaration I have made all the inquiries that I believe are desirable and appropriate and no matters of significance which I regard as relevant have to my knowledge been withheld from the Panel. V January 2018 Commercial in Confidence 12

16 Manningham Planning Scheme Amendment C109 ANNEXURE CV OF ROBERT CAMPBELL SWAN V January 2018 Commercial in Confidence 13

17 Robert Swan Current Position Principal, Hydrology and Hydraulics Section Leader Water Engineering, Cardno Profession Engineer Years' Experience 16 Joined Cardno January 2003 Education Bachelor of Engineering Diploma of Project Management Summary of Experience Robert is a Principal Engineer at Cardno and leads the Water Engineering team in the Victorian office. He has over fifteen years' experience in the areas of hydrology and hydraulics, flood analysis, water quality and environmental assessment. He has significant project management experience and has worked on a number of large multi-disciplinary projects. Rob is an expert in floodplain management and the simulation and modelling of large flood events and has assisted the Victorian State Emergency Service in emergency flood response. His expertise spans such models as Delft3D, SOBEK, RORB, TuFlow, URBS, MIKE11 and XP-STORM. Rob has authored and delivered training courses on flood modelling and WSUD. Rob has also assisted in the development of floodplain modelling guidelines for Melbourne Water. Rob has authored papers and presented at multiple national and international conferences. Key areas of experience include: > Floodplain Modelling and analysis > One and two-dimensional numerical model development and application for the study of flooding and water quality > Hydraulic and hydrologic investigations of urban and rural floodplains > Water quality investigations of shallow lakes and Water Sensitive Urban Design > Floodplain management and planning > Coastal Vulnerability Assessments > Environmental and geomorphological assessment > Flood Emergency Response and Planning > Project Management > Expert Witness Services Significant Projects > Port Hedland Coastal Vulnerability Study > Broome Coastal Vulnerability Study > Upper Murray River Regional Flood Mapping Project > SES Expert Hydrologist for the 2010, 2011 and 2012 Victorian Floods. > Western Distributor Tender Design Flooding Lead > Seymour Flood Levee Peer Review > Euroa Post Flood Mapping and Intelligence Project. > North Warrnambool Flood Study (Project Manager). > Latrobe River Flood Study (Project Director) > Koo Wee Rup Flood Protection District Flood Mapping and Mitigation Analysis > Melbourne Water Flood Plain Mapping Projects > Melbourne Desalination Plant Joint Venture. > Port of Melbourne Channel Deepening Project ROBERT SWAN Page 1 of 5

18 Professional History July Current Manager, Water Engineering Rob manages the Victorian Water Engineering Group, who specialise in floodplain studies, hydrological and hydraulic modelling, water quality and WSUD, Integrated Water Cycle Management, river geomorphology and emergency flood response. Significant projects include: > Port Hedland Coastal Vulnerability Assessment - Rob managed the hydrological and hydraulic modelling of the impact of severe flood and storm surge events for the Port Hedland region in Western Australia. This included joint probability assessment of ocean and riverine flood events. > Broome Coastal Hazard Vulnerability Study - Rob managed the hydrological and hydraulic modelling of the impact of severe flood and storm surge events for Broome in Western Australia. > Flood Lead, Western Distributor Tender Design - Rob was the design lead for flooding for the Western Distributor Tender Design. The project is a 5.5 Billion tunnel and freeway upgrades and included crossings of 4 major waterways. The analysis of a new bridge crossing of the Maribyrnong River included consideration of PMP and climate change flooding and the navigational requirements of commercial and recreational craft on the river. > SES Expert Hydrologist, 2012 Broken Creek Flood Event - Rob was one of two external experts brought in to provide hydrological and hydraulic analysis as part of the incident response to flooding on the Broken Creek. His work included public meetings and liaison, flood impact prediction, hydrological assessment and flood impact assessment. > Hamilton Flood Study - Rob was the project director for the Hamilton Flood Study that included hydrological and hydraulic analysis, floodplain modelling, community consultation and the development of flood prediction algorithms. The flood predictions utilised a model approach where predicted rainfalls were compared to a suite of model results to generate an estimate of the expected flood extent. > Mornington Peninsula Shire Flood Mapping Guidelines - Rob wrote the flood mapping technical guidelines for the Mornington Peninsula Shire Council > Koo Wee Rup Flood Event Analysis - Rob was the project manager and lead technical engineer for the assessment of flooding in the Koo Wee Rup area for planning purposes. He also undertook a detailed post event analysis of the 2011 flood event and determined the hydrological and hydraulic conditions that occurred during the storm. > Echuca Bridge Crossing - Rob has provided design and technical advice to VicRoads on the required bridge and culvert requirements for the proposed second crossing of the Murray and Campaspe Rivers at Echuca. This advice included flood impact assessment, mitigation sizing, preliminary costing, water quality and quantity assessment and community consultation. May July 2011 Manager, Water and Environment Melbourne Rob managed the Melbourne office of the Water and Environment team. Significant projects include: > Warrnambool Drainage Analysis - Provided advice and assistance to the City of Warrnambool in the development of a number of drainage strategies for developing areas in Warrnambool, including Dennington, the Warrnambool ROBERT SWAN Page 2 of 5

19 North-East activity precinct and the Warrnambool Eastern Activity Precinct. The strategies included the specification of drainage works, their type and location, cost estimates and the specification of water quality treatments to protect downstream waterways. These strategies have been adopted by the City and now form part of the overall drainage plan for these areas. > Victorian Desalination Plant Design - Rob provided advice and assistance to Thiess Degremont on hydrodynamics and water quality at the inlet and outlet structures of the deslaination plant, including the concept design of the diffusers. In addition, Rob was involved in the risk assessment workshops and authority liaison for the project. > Port of Melbourne Channel Deepening Project - Rob undertook assessment and analysis of the impacts on water quality and sediment transport in Port Phillip Bay as part of the EES for the Channel Deepening Project. His work included numerical modelling, field data collection and analysis, project reporting and client liaison. > Kew Main Drain Flood Mapping and Redevelopment Services Scheme Project - This projects includes hydrological and hydraulic modelling and flood mapping of existing and fully developed catchment conditions. The conceptual design of drainage structures to cater for the projected increase in development of the catchment is a key outcome of the project. > Hawthorn Main Drain Flood Mapping and Redevelopment Services Scheme Project - This project includes hydrological and hydraulic modelling and flood mapping of existing and fully developed catchment conditions. The SOBEK modelling system was used to define flood depths, extents and safety risk for the suburbs of Hawthorn, Glenferrie and Camberwell. The project included analysis of the impact of supercritical flows in drainage elements on flood extent. > Glenelg Flood Investigations - Flood modelling and assessment of flood extents for three towns in the Glenelg Shire: Portland, Casterton and Heywood. The study provided council with updated inundation and risk mapping to inform planning decision making and included the assessment of floodway areas. The projects outputs were an order of magnitude more accurate than the previous extents used by Council and the information provided could be used for emergency response purposes in the future. Jan May 2007 Project Engineer, Cardno Lawson Treloar Significant projects include: > Fairfield Main Drain Flood Mapping and mitigation Project > Mountain View Quarry Point Wilson EES (surface water components) > Great Mackerel Beach Flood > Dandenong Rail Corridor Surface Water Impact Assessment Hume and Melton Growth Corridor Planning Assessment. > Strathmerton Bypass > Bell Street Retarding Basin Assessments > Glass's Creek Flood Study Oct Jan 2003 Catchment Planner, Melbourne Water Corporation Undertook catchment planning and drainage analysis for Melbourne Water Corporation, including the following tasks:catchment Planning and Hydrology ROBERT SWAN Page 3 of 5

20 > Project Management > Application and analysis of Water Sensitive Urban Design > Implementation of Best Practice Environmental Management, Guidelines for Urban Stormwater > Water quality treatment modelling > Conceptual design of water quality and hydraulic works > Planning and analysis of road drainage crossings. Publications September 2016 Adaptive Floodplain Planning - from modelling to implementation Veldema, A, and Swan, R. Proceedings of the 4th National Conference of Stormwater Australia, August- September 2016 December 2015 Transforming Flood Mapping Outputs to Decision Making Inputs Veldema, A, and Swan, R. Proceedings of the 36th National Hydrology and Water Resources Symposium December 2015 Ocean Inundation, climate change and policy planning is the Flood approach suitable? Swan, R, Provis, D and Bicknell, P. Proceedings of the 36th National Hydrology Water Resources Symposium Feb 2013 Representing flood mechanisms in the Koo Wee Rup Flood Protection District Swan, R and Thompson A Presented at the 8th Victorian Flood Conference, February 2013 Feb 2013 Flood Mapping without Drainage Asset Data Thompson A and Swan, R Presented at the 8th Victorian Flood Conference, February 2013 Jun 2011 Direct Rainfall - Verifying the technique across two States Swan, R and Thomson R Proceedings of the 34th IAHR World Congress and the 33rd National Hydrology and Water Resources Symposium and the 10th National Conference on Hydraulics in Water Engineering ROBERT SWAN Page 4 of 5

21 Oct 2010 Direct Rainfall - Loss Modelling Approaches Swan, R. Presented at the 7th Victorian Floodplain Management Conference Oct 2010 Ocean versus River - Coastal Interfaces, Climate Change and Flood Analysis Swan, R. and Provis, D. Presented at the 7th Victorian Floodplain Management Conference Oct 2007 Dealing with Hydrological Uncertainty: A New Modelling Approach Swan, R. Presented at the 5th Victorian Floodplain Management Conference Oct 2005 Flood Studies and Extreme Events - Modelling, Mitigation and Assessment at Fairfield, Victoria Swan, R. Presented at the 5th Victorian Floodplain Management Conference. Dec 2004 Application of Australian Runoff Quality Draft Chapter 6 - A 'model' approach? Swan, R. 6th International Conference on WSUD - Cities as Catchments (WSUD 2004) Jul 2004 Integrated High Order Water Quality and Hydrodynamic Analysis - An Essential Tool for Lake Management Swan, R. 8th National Conference on Hydraulics in Water Engineering (2004). ROBERT SWAN Page 5 of 5

22 Manningham Planning Scheme Amendment C109 ANNEXURE DECEMBER 2017 SBO AND LSIO EXTENTS V January 2018 Commercial in Confidence 15

23 V January 2018 Commercial in Confidence 16

24 Manningham Planning Scheme Amendment C109 ANNEXURE MELBOURNE WATER - FINALISING FLOOD EXTENTSFOR INCLUSION IN PLANNING SCHEMES V January 2018 Commercial in Confidence 1

25 Finalising Flood Extents for Inclusion in Planning Schemes Background New 1% Annual Exceedance Probability flood extents need to be added to Council planning scheme overlays (either Land Subject to Inundation Overlay (LSIO) for flows associated with Melbourne Water s waterways or the Special Building Overlay (SBO) for overland flows associated with our underground assets). Alternatively, if an overlay already exists it needs to be amended in accordance with the new flood extent. The purpose of adding the flood mapping extents to the overlay is to ensure that any development that occurs within the overlay gets referred to relevant Authorities for provision of advice. In some cases parcels get included in the overlay with very minor coverage of the overlay on their parcel see example below: Figure 1 - example of parcel with minimal flood extent coverage In these cases we need to weigh up the value to the customer of having such a small overlay on their parcel vs the very small risk associated with taking them out. Several flood extents were used in a pilot to look at parcels with minimal coverage of the flood extent to inform a decision on how to balance the risk vs the benefit to the customer. From this work the following draft rules were developed to review parcels with minor encroachments from the flood extent and to determine if they should be in the SBO or LSIO or not. We also need to consider the benefit to the customer of minor changes to the flood extent / overlay within a parcel that result in no material difference in the referral intent. 1

26 Rules 1. If the new flood extent is within an area that already has a Special Building Overlay (SBO) or Land Subject to Inundation Overlay (LSIO) on it and modifying the SBO or LSIO would not materially* change the effect of the overlay, retain the existing SBO or LSIO. *Please see Example 1 below for an example of materially affecting the SBO / LSIO. 2. If the flood extent is required for continuation of the flood extent from upstream to downstream then use the new flood extent as it is (no modification). For example, removing the small triangular flood extent from the south-east corner of this parcel would result in an unrealistic-looking flood extent around that location. Figure 2 - Example of where the flood extent would be left as it is because it would create an unrealistic looking flood extent 3. If the percentage of the parcel covered by the flood extent is 2% or more then adopt the new flood extent as it is (no modifications). This value of 2% was selected by examining many parcels that had coverage of around 2% and using engineering judgement to select the percentage. This value will be reviewed over time to see whether it can be improved. 4. If the percentage of the parcel covered by the flood extent is below 2% then use engineering judgment considering: a. Length of frontage affected If >= 25% of the frontage has the flood extent over it, use the new flood shape as it is (no modifications). For the purpose of this work frontage means a parcel boundary along a road. Special attention needs to be given to this situation because if development occurs that includes a car park, garage or other room below ground there is a risk of floodwater flowing down into the underground area. b. Number, location and depth of points within the extent More points within that part of the extent that is within the parcel makes it more likely that the new extent should be adopted (no modifications). Older flood extents were created using a point density method that often resulted in the flood extent being just inside or outside of the points i.e. parts of the flood extent may not have had points within them, and a few points that ideally should have been in the flood extent weren t. The current flood extent creation method using the Feature Manipulation Engine doesn t have this issue. 2

27 Examples: Example 1 GIS: Example 1 Details: This is an example of Rule 1. Applying the other rules would result in the new flood extent being retained through this area. However, changing the SBO from the grey shape to the new flood shape would not materially alter the way the SBO is applied to these parcels. Decision: Retain the existing SBO shape as the flood shape and merge it into the new flood shape on the western and eastern sides as shown in Example 2. Example 2 3

28 Example 3 GIS: Example 3 Details: This parcel fronts a road. However, the overlay area is only 0.25% of the parcel area, the depth on the parcel is 0.027m, less than 25% of the frontage has water over it, and there is only 1 point within the overlay. Decision: Modify the flood extent to be just outside of the subject parcel. Example 4 GIS: Example 4 Details: Overlay area is 0.8% of parcel area, depth is 0.038m, overlay is in rear corner of parcel (not along a road) Decision: Modify the flood extent to be just outside both parcels 4

29 Example 5 GIS: Example 5 Details: Overlay area is 1.6% of parcel area, depth is 0.054m, rear of parcel, only 1 point within the parcel Decision: Modify this flood extent to be just outside of this parcel Example 6 GIS: Example 6 Details: Overlay area is 1.7% of parcel area, depth is 0.068m, overlay covers 30% of road frontage Decision: This parcel needs to remain in the SBO. Leave the flood extent as it is. 5

30 Example 7 GIS: Example 7 Details: Overlay area is 1.8% of parcel area, depth is 0.53m, overlay is on side of parcel Decision: Modify this flood extent to be just outside of the parcel. Example 8 GIS: Example 8 Details: Overlay area is 2% of parcel area. No need to examine further. (Depth is 0.65m, overlay covers 31% of road frontage) Decision: This parcel needs to remain in the SBO. Leave the flood extent as it is. 6

31 Example 9 GIS: Example 9 Details: Overlay area is 2% of parcel area. No need to examine further. (Depth is 0.051m, overlay covers approximately 75% of the road frontage) Decision: This parcel needs to remain in the SBO. Leave the flood extent as it is. Example 10 GIS: Example 10 Details: Overlay area is 2.1% of parcel area. No need to examine further. (Depth is 0.43m, overlay covers 85% of road frontage) Decision: This parcel needs to remain in the SBO. Leave the flood extent as it is. 7

32 Example 11 GIS: Example 11 Details: Overlay area is 2.2% of parcel area. No need to examine further. (Depth is 0.069, overlay covers 30% of the road frontage) Decision: This parcel needs to remain in the SBO. Leave the flood extent as it is. Example 12 GIS: Example 12 Details: Clearly only a very small percentage of the parcel is covered by the overlay, and it touches far less than 25% of the road frontage. Decision: Modify this flood extent to be just outside the parcel. 8

33 Example 13 GIS: Example 13 Details: Clearly only a very small percentage of each parcel is covered by the overlay, which touches far less than 25% of the road frontage of each parcel. Decision: Modify the flood extent to be just outside both of these parcels. Example 14 GIS: Example 14 Details: Clearly only a very small percentage of the parcel is covered by the overlay, and it touches far less than 25% of the road frontage. Decision: Modify this flood extent to be just outside the parcel. 9

34 Example 15 GIS: Example 15 Details: Clearly the area of the flood extent within this parcel is much less than 2%. Decision: Modify the flood extent to be just outside of this parcel. Examples of Modifying the Flood Extent Example 16 10

35 Example 17 Example 18 Melbourne Water Corporation June

36 Manningham Planning Scheme Amendment C109 ANNEXURE SUBMISSION ASSESSMENT V January 2018 Commercial in Confidence 3

37 4 Birchgrove Crescent, Templestowe (37) The submitter issue: Disputes flow path Key Findings Submitter/Council Concerns Disputes flow path Final Comments Response Agreed. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from the property. SBO has been removed from property Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from property V January 2018 Commercial in Confidence 4

38 Mullum Creek Estate, Donvale (46) The submitter issue: Submitter is worried about planning permits on the site, as they were approved to the Existing LSIO Key Findings Submitter/Council Concerns Submitter is worried about planning permits on the site, as they were approved to the Existing LSIO Final Comments Response As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property. This should now no longer affect planning permits for the development The new modelling indicates a slightly smaller LSIO overlay across the property. The LSIO area could be reduced from the current LSIO. From a risk perspective, maintaining the existing overlay, given it fully covers the new overlay provides an appropriate control for flooding. Conclusions and Recommendations Proposed Resolution for Property Outcome: Abandon proposed changes (as an alternate, amend LSIO to the reduced shape) V January 2018 Commercial in Confidence 5

39 20 Montpellier Crescent, Templestowe Lower (65) The submitter issue: What is the minimum freeboard above and what is the AHD for this property? What do say are the ranges in elevation are for this property? What study did you use to determine 1% flood level? Key Findings Submitter/Council Concerns What is the minimum freeboard above and what is the AHD for this property? What do say are the ranges in elevation are for this property? What study did you use to determine 1% flood level? Final Comments Response The maximum modelled flood elevation on the property was 40.4mAHD. Which is located at an area where the ground surface level is 40.3mAHD. From LiDAR data, the ground level of the property ranges in elevation from mahd to mahd. Hydraulic modelling of this area was undertaken as part of the Ruffey Creek Flood Mapping project undertaken by AECOM (dated 16/04/2013). As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property. V January 2018 Commercial in Confidence 6

40 Conclusions and Recommendations Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 7

41 8 Chaim Court, Donvale (71) The submitter issue: Street has flooded but never their property. Is flow path constant with actual ground form? Key Findings Submitter/Council Concerns Street has flooded but never their property. Is flow path constant with actual ground form? Final Comments Response Yes, water will flow from Chaim Court, over the kerb and down through the property. This is not due to Melbourne Water assets however, it is due to council assets on Chaim Court. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 8

42 65 Dehnert Street, Doncaster East (75) The submitter issue: Retaining walls exist along north and east property boundaries, and land falls to east and north Key Findings Submitter/Council Concerns Retaining walls exist along north and east property boundaries, and land falls to east and north Response Modelling results show that flooding of the property is being caused by water emanating from the underground drain which runs along the southern boundary of the property. The model indicates in a design 1% AEP flood event, this drain will reach capacity and overflow into the subject property. Final Comments Flooding in this property is due to council drainage reaching capacity, not Melbourne Water drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from the property. V January 2018 Commercial in Confidence 9

43 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from property V January 2018 Commercial in Confidence 10

44 6 Hillcroft Drive, Templestowe (96) The submitter issue: Submitter disputes water entering property at all. Key Findings Submitter/Council Concerns Submitter disputes water entering property at all. Final Comments Response This property included overland flows from the Council drainage network. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from the property. SBO has been removed from property Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from property V January 2018 Commercial in Confidence 11

45 10 Hillcroft Drive, Templestowe (113) The submitter issue: Hasn t seen flooding on property in the 24 years living on property. Front door is 6m above street level Key Findings Submitter/Council Concerns Hasn t seen flooding on property in the 24 years living on property. Front door is 6m above street level Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe. The SBO does not affect the dwelling, and only includes the frontage of the property.. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property to what is shown below V January 2018 Commercial in Confidence 12

46 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to be retained as above V January 2018 Commercial in Confidence 13

47 12 Hillcroft Drive, Templestowe (126) The submitter issue: Hasn t seen flooding on property in the 27 years living on property. Front door is 6m above street level Key Findings Submitter/Council Concerns Hasn t seen flooding on property in the 27 years living on property. Front door is 6m above street level Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe. The SBO does not affect the dwelling, and only includes the very edge of the property, running up the driveway and behind the retaining wall for a short period. It will have no effect on the property. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property to what is shown below V January 2018 Commercial in Confidence 14

48 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to be retained as above V January 2018 Commercial in Confidence 15

49 16 Nottingwood Street, Doncaster East (143) The submitter issue: Claims that water level won t get to 5m above the road level. Catchment won t produce the flooding that is shown Key Findings Submitter/Council Concerns Claims that water level won t get to 5m above the road level. Catchment won t produce the flooding that is shown Final Comments Response Water is not flowing up from the road level, but is coming from the rear of the property. This was explained during a meeting between Cardno and the submitter and this was acknowledged by the submitter. Flooding is not caused by upstream overland catchment, but by council drainage reaching capacity as the drainage network turns west at the rear of the property and reduces from a 450mm to a 375mm diameter pipe. Flooding in this property is due to council drainage reaching capacity. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO boundary has been redefined to the road and removed from the property. V January 2018 Commercial in Confidence 16

50 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from property V January 2018 Commercial in Confidence 17

51 5 Mossy Creek Slope, Warrandyte (145) The submitter issue: Previous flooding (burst water main) has not affected property, but affected 6 Mossy Creek Slope. Key Findings Submitter/Council Concerns Previous flooding (burst water main) has not affected property, but affected 6 Mossy Creek Slope. Final Comments Response From this site inspection it is evident that the neighbouring driveway (6 Mossy Slope Creek) will experience overland flooding before 5 Mossy Creek Slope will get any inundation. As a result, the flow path has been amended and removed from 5 Mossy Creek Slope. Flooding in this property is due to council drainage reaching capacity, not Melbourne Water drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 18

52 7 Montclair Court, Templestowe (152) The submitter issue: Flooding won t occur as shown Key Findings Submitter/Council Concerns Flooding won t occur as shown Final Comments Response The flooding shown in the initial mapping included overland flows associated with council drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property LSIO has been removed from the property Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 19

53 5 Trudi Court, Donvale (170) The submitter issue: 20 years at property and never witnessed flooding. Key Findings Submitter/Council Concerns 20 years at property and never witnessed flooding. Final Comments Response The SBO overlays have been developed based on the theoretical 1 in 100 year rainfall event. Therefore, it is highly likely that no flooding has occurred as represented by the proposed SBOs in the last 20 years. Flooding in this property is due to council drainage reaching capacity, not Melbourne Water drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from the property. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from property. V January 2018 Commercial in Confidence 20

54 35 Lynnwood Parade, Templestowe Lower (184) The submitter issue: Mapped flood extent doesn t appear to represent reality Key Findings Submitter/Council Concerns Mapped flood extent doesn t appear to represent reality Final Comments Response Model results were analysed which indicate that the flooding on this property is caused by water emanating from the Council underground drain running along the back of the subject property which has reached capacity in the theoretical 1 in 100 year rainfall event The LiDAR and contour surface data as well as site photos were analysed, indicating that the model was not reflective of the actual topography in this area. This created several localised low points which have led to misleading flood modelling results from the Council network. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from the property. V January 2018 Commercial in Confidence 21

55 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from property V January 2018 Commercial in Confidence 22

56 6 Montclair Court, Templestowe (253) The submitter issue: Flooding won t occur as shown Key Findings Submitter/Council Concerns Flooding won t occur as shown Final Comments Response The flooding shown in the initial mapping included overland flows associated with council drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property LSIO has been removed from the property Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 23

57 26 Hillcroft Drive, Templestowe (340) The submitter issue: Property hasn t flooded in the 28 years the submitter has lived on property. Key Findings Submitter/Council Concerns Property hasn t flooded in the 28 years the submitter has lived on property. Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property to what is shown below Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to be retained as above V January 2018 Commercial in Confidence 24

58 18 Amberwood Court, Templestowe (344) Key Findings Submitter/Council Concerns Final Comments Response Based on LiDAR and surface contour data as well as site photos, the flood shape associated with the driveway on the south-east is unlikely to occur. The driveway is at a steep enough slope where water will not come into the property from the road as far as suggested. The flood shape on the western side of the property also looks unlikely to occur. The brick wall on the property boundary has not been picked up by LiDAR. Water therefore unlikely to enter from Amberwood Court as suggested. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO has been removed from the property V January 2018 Commercial in Confidence 25

59 24 Hillcroft Drive, Templestowe (345) The submitter issue: Property hasn t flooded in the 26 years the submitter has lived on property. Key Findings Submitter/Council Concerns Property hasn t flooded in the 26 years the submitter has lived on property. Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property to what is shown below Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to be retained as above V January 2018 Commercial in Confidence 26

60 5 Dilkara Court, Doncaster East (368) The submitter issue: Doesn t believe flooding would occur on his property from Mullum Mullum Creek. Key Findings Submitter/Council Concerns Doesn t believe flooding would occur on his property from Mullum Mullum Creek. Final Comments Response Modelling results were investigated and showed that the flooding is occurring from the council drainage at the north of the property reaching capacity, causing overflow from the drain. It is not caused by a rising water level in Mullum Mullum Creek. Flooding in this property is due to council drainage reaching capacity, not Melbourne Water drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from the property. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 27

61 8 Montclair Court, Templestowe (378) The submitter issue: Flooding won t occur as shown Key Findings Submitter/Council Concerns Flooding won t occur as shown Final Comments Response The flooding shown in the initial mapping included overland flows associated with council drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property LSIO has been removed from the property Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 28

62 6 Raymond Elliot Court, Park Orchards (381) The submitter issue: Key Findings Disagree that water flowing from rear of property, down onto Raymond Elliot Court is to do with a watercourse and instead is to do with a pipe overflow, so shouldn t be classified as LSIO Submitter/Council Concerns Disagree that water flowing from rear of property, down onto Raymond Elliot Court is to do with a watercourse and instead is to do with a pipe overflow, so shouldn t be classified as LSIO Final Comments Response Flooding is likely to occur on property, however is caused by overflowing council assets. They are not caused by Melbourne Water assets, and so has been removed from the overlay A small area crosses into the property in the south-west corner of the property, however as this area is < 2% of the property area, and cover < 25% of the street frontage, it can also be removed from the property As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property V January 2018 Commercial in Confidence 29

63 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO to be removed from property. V January 2018 Commercial in Confidence 30

64 16 Hillcroft Drive, Templestowe (388) The submitter issue: Overlay is within property but is not in 11,13 or 15 Hillcroft Drive. Has not seen flooding threatening his house for almost 30 years he has lived at 16 Hillcroft Drive Key Findings Submitter/Council Concerns Overlay is within property but is not in 11,13 or 15 Hillcroft Drive. Has not seen flooding threatening his house for almost 30 years he has lived at 16 Hillcroft Drive Final Comments Response The flood enters all neighbouring properties within Hillcroft Drive, including 11, 13 and 15 Hillcroft Drive. This is shown in the figure below. The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been removed from most of the property. The SBO is still applied to the front of the property, 4.7m at a maximum from the property boundary V January 2018 Commercial in Confidence 31

65 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO will be retained as shown V January 2018 Commercial in Confidence 32

66 2 Eumeralla Avenue, Templestowe Lower (392) The submitter issue: Does not support overlay as more of the property is impacted by LSIO Key Findings Submitter/Council Concerns Does not support overlay as more of the property is impacted by LSIO Final Comments Response The property has two flow paths through it which discharge to Ruffey Creek adjacent to the property. The main flow path is to the south which follows the path of an underground drain. The site inspection identified that this southern flow path is likely too large as indicated by the modelling results. The area directly to the north of the drain ramps up steeply by approximately 1.5 meters to the flood level of the house. This feature has not been adequately picked up in the modelled surface. This has likely been caused by the tree being inadequately thinned from the LiDAR as well as model resolution issues. Therefore, it is recommended that a small section of this flow path be removed from the overlay as indicated by the figure below. The northern flow path follows the low points of the terrain as confirmed by the site visit and is likely to flood. However, this is associated with council drainage and is no longer included in the proposed LSIO. The flooding is not attributed to the flooding of Ruffey Creek, and comes from upstream of the property. It is therefore not part of the Melbourne Water LSIO and has been removed. V January 2018 Commercial in Confidence 33

67 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 34

68 14 Hillcroft Drive, Templestowe (394) The submitter issue: Hasn t seen flooding on property in the 17 years living on property. Front door is 7m above street level Key Findings Submitter/Council Concerns Hasn t seen flooding on property in the 17 years living on property. Front door is 7m above street level Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe. The SBO does not affect the dwelling, and only includes the very edge of the property as shown in the figure below. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property to what is shown below V January 2018 Commercial in Confidence 35

69 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO will be retained as shown. V January 2018 Commercial in Confidence 36

70 50-52 and Ennismore Crescent, Park Orchards (427) The submitter issue: Key Findings Claims Area A should not be SBO1 as not related to Melbourne Water asset Inappropriate flood modelling and filtering techniques were used that didn t filter shallow flows on steep slopes. Areas B and C should be removed as they are narrow strips Submitter/Council Concerns Submitter claims that Area A should not be SBO1 as is not related to the Melbourne Water asset Submitter claims that inappropriate flood modelling and filtering techniques were used that didn t filter out shallow flows on steep slopes Submitter claims that Areas B and C should be removed as they are narrow strips Final Comments Response Yes this is correct, the hill is very steep and the flooding unrelated to the MW asset. It is correct that the flood shape is not well represented as there has been some LiDAR tinning issues due to the removal of the buildings and the steep catchment. There is however an easement on the property that does convey overland flows so there are known flow paths there. Shape has been adjusted to reflect these comments. Flooding from the north is due to council drainage reaching capacity, not Melbourne Water drainage. Therefore, it will be removed. The SBO at the south-western corner of Ennismore Crescent can also be removed. From aerial imagery, flooding here seems unlikely, and tinning issues may have occurred due to the clump of vegetation between and Ennismore Crescent V January 2018 Commercial in Confidence 37

71 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to be removed from properties. V January 2018 Commercial in Confidence 38

72 Mossdale Court and Greenridge Avenue, Templestowe (427A) The submitter issue: Questioning modelling. Key Findings Submitter/Council Concerns Questioning Modelling Final Comments Response Water was applied to pits at the rear of the property in the local drainage network, in accordance with what the submission described as best practice. Floodwaters spill from these pits once their capacity is reached. The overlay has been refined in this area to remove the areas that are subject to flooding from the council network. Applying the strictly Melbourne Water s rules for SBO production the properties along Mossdale Drive would be included in the SBO as the proposed overlay covers >2% of property area or >25% of property frontage. However the extent of flooding is minimal on most of the properties and could be removed from those properties outlined in magenta. These properties are: 16 Mossdale Court 15 Mossdale Court 15A Mossdale Cour (inc. Common property) 1/14 Mossdale Court (inc. Common property) 2/14 Mossdale Court 2/13 Mossdale Court The flood shape should remain on: 18 Mossdale Court 17 Mossdale Court 28 Greenridge Avenue and otherwise as shown in the figure below. It is noted that the properties slope steeply upward from the roadway which acts as the overland flow path and the application of the SBO is unlikely to impact buildings and works on the properties. V January 2018 Commercial in Confidence 39

73 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to remain as shown above V January 2018 Commercial in Confidence 40

74 26 Harris Gully Road, Warrandyte (452) The submitter issue: Flood shape does not correlate to contours. Key Findings Submitter/Council Concerns Flood shape does not correlate to contours Final Comments Response This query relates to SBO2 and SBO3 overlays which were previously prepared for Manningham City Council. Only the Melbourne Water controlled overlays are moving forward, and do not affect the property. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from property V January 2018 Commercial in Confidence 41

75 28 Harris Gully Road, Warrandyte (454) The submitter issue: Key Findings 26 Harris Gully Road has been developed, and local stormwater runoff measures have been taken to remove flooding from the 1 in 100 year event. Submitter/Council Concerns 26 Harris Gully Road has been developed, and local stormwater runoff measures have been taken to remove flooding from the 1 in 100 year event. Final Comments Response Flooding from 26 Harris Gully Road into the property has been removed from the flood overlays. This is shown in the figure below. The flood overlay is retained over the south-east corner of the property, and is caused by flooding of Harris Gully. V January 2018 Commercial in Confidence 42

76 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: Retain LSIO as shown V January 2018 Commercial in Confidence 43

77 30 Hillcroft Drive, Templestowe (460) The submitter issue: No specific comment Key Findings Submitter/Council Concerns Final Comments Response As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced within the property to what is shown below Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to remain as shown above V January 2018 Commercial in Confidence 44

78 50 Windella Quadrant, Doncaster (471) The submitter issue: Filling has occurred on property and there should not be SBO 2 in part of property Key Findings Submitter/Council Concerns Filling has occurred on property and there should not be SBO 2 in part of property Final Comments Response SBO2 is no longer being pursued as part of the flood overlays for the property. Only flooding attributed to Melbourne Water assets have been included, hence SBO2 has been fully removed from the overlay. LSIO to the rear of the property is to be removed. This flooding is not due to Koonung Creek, but to do with flow from upstream through the property. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO to be removed from property. V January 2018 Commercial in Confidence 45

79 5 Chaim Court, Donvale (482) The submitter issue: Flooding does not occur how overlays show, should occur in 3 Chaim Court as well Key Findings Submitter/Council Concerns Flooding does not occur how overlays show, should occur in 3 Chaim Court as well Final Comments Response The flood overlays show that the flooding also occurs through the south-east corner of 3 Chaim Court. Flooding then enters the road reserve and continues to the low point at 8 Chaim Court. Water does flow via the suggested path within the submission. In September 2017, Cardno prepared a report for Manningham City Council in which the overlay through the property was changed to being council owned. As Council overlays have been abandoned, so too has the overlay from the property. V January 2018 Commercial in Confidence 46

80 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO has been removed from the property V January 2018 Commercial in Confidence 47

81 23-31 Tills Drive, Warrandyte (505) The submitter issue: Issues with flooding running through the property from Tills Road. Key Findings Submitter/Council Concerns Issues with flooding running through the property from Tills Road. Final Comments Response Originally, each property was given one flood overlay category. As only Melbourne Water are pursuing the flood overlays, only Melbourne Water overlays are now provided. It was decided that the original overlay running from Tills Road was due to Council drainage, not Melbourne Water assets. Flooding for Tills Drive will occur from flooding of the Yarra River. The LSIO for the property will only include the previous Yarra River LSIO. V January 2018 Commercial in Confidence 48

82 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: Remove new LSIO (no change to the existing LSIO as shown above) V January 2018 Commercial in Confidence 49

83 110 McGowans Road, Donvale (529) The submitter issue: Objects to flood shape on southern boundary, not along the rear of the property. Key Findings Submitter/Council Concerns Objects to flood shape on southern boundary, not along the rear of the property. Final Comments Response In September 2017, Cardno prepared a report for Manningham City Council in which the overlay along the southern boundary of the property was changed to being council owned. As Council overlays have been abandoned, so too has the part of the overlay from the property. The LSIO has been refined to what is shown below. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO and LSIO to be retained as shown above V January 2018 Commercial in Confidence 50

84 18 Hillcroft Drive, Templestowe (536) The submitter issue: Not experienced flooding after having been at the property for 18 years. Key Findings Submitter/Council Concerns Not experienced flooding after having been at the property for 18 years. Final Comments Response The closest pluviograph location is 2.23km away at Zerbes Reserve. The critical duration for the property varies, however the largest storm event in the last 18 years was on the 3rd December 2003, where the 60 minute storm was a 1 in 28.1 year event. This is much smaller than the theoretical 1 in 100 year event that the SBO is based on. This likely explains why there has been no flooding observed. Flooding in the rear property is due to council drainage reaching capacity, not Melbourne Water drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced from the back of the property, and maintained at the front of the property as flooding at the front of the property is associated with Melbourne Water assets. V January 2018 Commercial in Confidence 51

85 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: SBO to remain as shown above V January 2018 Commercial in Confidence 52

86 12 Jolen Court, Donvale (544) The submitter issue: Seeking Council help regarding planning permits Key Findings Submitter/Council Concerns Final Comments Response The property sits in a significant flow path from Era Court, into Mullum Mullum Creek. The flooding that occurs is due to council drainage not having capacity, and not due to Melbourne Water assets. As part of an overlay refining project completed in December 2017 for Melbourne Water, the LSIO has been removed from the property, and will be removed from the property for 11 and 12 Jolen Court. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO to be removed from 11 and 12 Jolen Court V January 2018 Commercial in Confidence 53

87 2 Aquarius Court, Donvale (559) The submitter issue: Key Findings Not seen flooding occur since purchasing in September Water won t enter property, as it is 6m above the creek. Footpath also 3m above creek behind property Submitter/Council Concerns Not seen flooding occur since purchasing in September 1993 Water won t enter property, as it is 6m above the creek. Footpath also 3m above creek behind property Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe. Flooding enters the property from the south-west corner of the property. It then flows north, mostly following the line of Mullum Mullum Creek. The property has an overlay between the fence line and Mullum Mullum Creek, and will not affect the property or dwelling within the fence boundary. It is recommended to retain the proposed LSIO within the property. Modelling of the 1 in 100 year event shows flooding behind the property of depths up to 5m within Mullum Mullum Creek itself. This will affect the rear of the property, behind the fenceline, but inside the property boundary. V January 2018 Commercial in Confidence 54

88 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: Retain LSIO as shown above V January 2018 Commercial in Confidence 55

89 13, 15, 17, 19 and 21 Mopoke Hill Road, Warrandyte (561, 562, 563, 564 and 565) The submitter issue: No risk of home being flooded due to be 20m above creek level. Property only flooding due to property touching road side reserve Key Findings Submitter/Council Concerns No risk of home being flooded due to be 20m above creek level. Property only flooding due to property touching road side reserve Response Agreed. Flooding in the property dwellings is extremely unlikely from Harris Gully to the rear of the properties. The flood overlays are produced to determine safety and building measures required for development in flood affected areas. This overlay has no impact on the dwellings on the property, only development that would occur over the flood overlay The properties are larger, and go down into the flood extent of Harris Gully. The flood overlays are not related to the positioning of current dwellings on the properties, but are there for future developments within the property boundaries. Final Comments It is recommended that the flood overlay be removed from 13 and 15 Mopoke Hill Road, as the overlay enters a distance less that the model resolution (grid cell size) into these properties. The remaining properties will remain within the overlay V January 2018 Commercial in Confidence 56

90 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: Remove LSIO from 13 and 15 Mopoke Hill Road. Retain LSIO in 17, 19 and 21 Mopoke Hill Road V January 2018 Commercial in Confidence 57

91 21 Baradine Terrace, Donvale (567) The submitter issue: Lived on property since 1994, has seen no flooding occur. Key Findings Submitter/Council Concerns Lived on property since 1994, has seen no flooding occur. Final Comments Response The flood overlays have been based on theoretical 1 in 100 year flood events. It is most likely that flooding suggested by the overlay has not occurred on the property in this timeframe. It has been recommended to remove the flood overlay from this property. The flood area takes up < 2% of the property area, and < 25% of the property frontage. Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: Remove LSIO from property. V January 2018 Commercial in Confidence 58

92 20 Russell Street, Bulleen (no submission number) The submitter issue: Claims no consideration was given to a Melbourne Water Drain installed on 22 Russell Street Key Findings Submitter/Council Concerns Claims no consideration was given to a Melbourne Water Drain installed on 22 Russell Street Final Comments Response From the latest Melbourne Water asset data, there is no Melbourne Water owned pipe within 22 Russell Street. In any case, flooding on the property is due to the Melbourne Water drainage to the rear of the property. The SBO at the front of the property has been removed. This flooding is due to council drainage reaching capacity, not Melbourne Water drainage. As part of an overlay refining project completed in December 2017 for Melbourne Water, the SBO has been reduced from the front of the property, but retained at the rear, where a Melbourne Water asset is located. V January 2018 Commercial in Confidence 59

93 Conclusions and Recommendations Based on the assessment of the flood modelling results Proposed Resolution for Property Outcome: LSIO to be retained as shown above V January 2018 Commercial in Confidence 60