Strategic Bushfire Risk Assessment for the Wangaratta Residential Growth Areas

Transcription

1 Strategic Bushfire Risk Assessment for the Wangaratta Residential Growth Areas Report commissioned by Rural City of Wangaratta Terramatrix 2014

2 Strategic Bushfire Risk Assessment for the Wangaratta Residential Growth Areas Terramatrix project code: RCW Report prepared by Terramatrix on behalf of Rural City of Wangaratta, 2014 Terramatrix Pty. Ltd. ACN ABN PO Box 1391 Collingwood VIC 3066 P: Approvals Accountability Report compilation Peer review Approval for release Name Alice Gower, Adam Redfern Hamish Allan Jon Boura Version control Date Comments Distribution 07/05/2014 Terramatrix internal Jon Boura review 09/05/2014 Draft to client Elise Newman 04/06/2014 Final report v2.0 Hamish Allan 26/06/2014 Final report v2.1 Hamish Allan Copyright Unless otherwise agreed in writing, this report is the intellectual property of Terramatrix. It is designed to be used exclusively by the person that commissioned it. Permission must be sought prior to the reproduction of any portion of this document and every effort made to ensure proper referencing of this document. Disclaimer This report may be of assistance to you and has been made with careful consideration and with the best information available to Terramatrix at the time of writing. Before relying on information in this report, users should carefully evaluate the accuracy, completeness and relevance of the information provided for their purposes. Terramatrix Pty Ltd, its directors and employees do not guarantee that it is without flaw or omission of any kind or is wholly appropriate for your particular purposes and therefore disclaim all liability for any error, loss or other consequence that may arise from you relying on any information in this report. GIS Data and Mapping Accuracy Spatial data supplied by Rural City of Wangaratta, State Government of Victoria. Care was taken when creating the maps used in this report however, the accuracy cannot be guaranteed. Users of maps should make appropriate enquiries to ascertain the accuracy and relevance of the information contained within them. Page 2 of 55

3 Contents 1 INTRODUCTION 6 2 METHODOLOGY STUDY APPROACH DOCUMENT REVIEW 9 3 THE CONTEXT SITE OVERVIEW LANDSCAPE CONTEXT EXISTING AND FUTURE USES FIRE HISTORY MUNICIPAL FIRE MANAGEMENT PLAN COMMUNITY INFORMATION GUIDE BUSHFIRE LOCAL FIRE SUPPRESSION RESOURCES DEPI FIRE OPERATIONS PLAN ACCESS AND EGRESS STATE PLANNING POLICY FRAMEWORK (SPPF) REGIONAL BUSHFIRE PLANNING ASSESSMENT PLANNING ZONES PLANNING OVERLAYS BUSHFIRE PRONE AREA (BPA) 23 4 THE RISK FROM BUSHFIRE BUSHFIRE BEHAVIOUR CFA LANDSCAPE SCENARIOS POTENTIAL MAJOR BUSHFIRE SCENARIOS POTENTIAL BUSHFIRE IMPACTS 39 5 ANALYSIS AND EVALUATION 42 6 PLANNING AND DESIGN RESPONSE GROWTH AREA LAYOUT CONSTRUCTION STANDARD DEVELOPMENT PATTERN DEFENDABLE SPACE PLANNING ACCESS PLANNING VULNERABLE USES HOUSING DENSITY EMERGENCY SERVICES WATER RESOURCES LANDSCAPING CONSIDERATIONS 53 7 REFERENCES 54 Page 3 of 55

4 Executive Summary Council have adopted the Rural City of Wangaratta Population and Housing Strategy (the Strategy). This document identifies two areas on the edge of the Wangaratta urban area as potential greenfield residential growth areas. One is to the west of the existing urban area and the other is to the south. This report assesses the bushfire risk associated with residential use in these areas by: Identifying the type and level/s of bushfire risk for both the western and southern growth areas for Wangaratta; Characterising and evaluating key bushfire risks; Identifying mitigation strategies to address the risk to existing, as well as the progressive expansion of the future urban interface in the short, medium and long term growth options, and Providing land use and urban design directions for consideration within future structure planning for the two growth areas. Planning Practice Note 64 - Local Planning for Bushfire Protection was used as a guide when assessing the bushfire risk. This included four main steps: Establish the context; Identify the risks from bushfire; Analyse and evaluate the risks; and Translate risk mitigation into planning scheme provisions (DTPLI, 2013). Terramatrix consider the proposals for residential growth to both the west and south of Wangaratta to be appropriate from a bushfire risk perspective. Some risk of impact from grassfire exists at these sites, however it can be adequately mitigated in the planning and implementation of the development. The planning and design response provides guidance towards achieving bushfire risk mitigation. The key recommendations and comments of Terramatrix are: Strongly support the Actions of 1-3 and 9 in Section of the Strategy as these planning stages offer a major opportunity for clarifying when and where bushfire mitigation measures should be used in the development and for integrating them with other design elements; Strongly support the proposal to create a link across Three Mile Creek in the vicinity of Cruse Street as this would create valuable emergency access and egress; Support the avoidance of leap-frog development as advocated in the Strategy; That the planning process consider an arrangement of housing, other land uses and associated access within the eastern portion of the western growth area that would be appropriate from a bushfire safety perspective whether development of the western portion proceeds or not; That Council choose one (or a combination) of the following two options for combatting potential radiant heat and flame contact: Page 4 of 55

5 o A BAL-12.5 construction of dwellings and a minimum defendable space buffer of 19 m from unmanaged grassland; o No BAL construction requirements for dwellings and a minimum defendable space buffer of 60m from unmanaged grassland (pending discussions with appropriate authorities to excise the future urban area from the BPA); That Council use perimeter roads to define development; That Council and the developer(s) should implement staged development in a west to east construction order; Where defendable space is planned to be provided on private land, Council should ensure that adequate planning controls exist to prevent dwelling construction closer to the hazard than planned; Council should plan a layout of defendable space that is integrated with the road and path network and other managed open space; Sporting grounds, golf courses and parks should be located on the outer edges of the growth areas; Subdivision planners should attempt to contain each development stage within bounding roads; A layout with numerous cul-de-sacs should be avoided; Council should consider additional through roads above the existing access provided by major roads at both sites; That the function of the roads as Fuel Reduced Corridors or Priority Access Roads for listing within the MFMP be reviewed in light of the changing land use; That vulnerable uses such as housing for the elderly, nursing homes, health facilities, schools, child care centres, etc. be located in the inner areas of the development rather than on the outer edges; Support for Actions 8 and 32 of the Strategy so long as medium density housing is not located on the development interface; Support some reduction in development density towards the Warby Ranges within the growth area, pending that the density of housing and/or continuity of fuels at the interface will not facilitate fire penetration more than the existing examples of LDRZ near the growth areas; Council should consult with CFA in regard to any need to provide for the provision of fire services for an expanded Wangaratta, particularly for the substantial increase of people and assets in the western growth area; and Council to consider developing a landscaping guide for new subdivisions particularly on the edge of the urban area abutting grassfire hazard, which recommends bushfire appropriate plant species, garden styles and fencing. Page 5 of 55

6 1 Introduction The Rural City of Wangaratta Council (Council) adopted the Rural City of Wangaratta Population and Housing Strategy (Aurecon, 2013) on 10 December This document provides strategic direction for population and housing growth in the municipality. Two areas on the edge of the Wangaratta urban area were identified as potential growth corridors. One is to the west of the existing urban area and the other is to the south (Refer Map 1). Providing land use and urban design directions for consideration within future structure planning for the two growth areas. As part of the consultation with emergency services regarding the Strategy, the Country Fire Authority (CFA) identified bushfire risk as a key issue requiring consideration in the development of structure plans for these growth areas. The Regional Bushfire Planning Assessment also highlights some bushfire issues particularly relating to the western growth area. This project will assist Council to understand and reduce the bushfire risk associated with residential use in these areas by: Identifying the type and level/s of bushfire risk for both the western and southern growth areas for Wangaratta; Characterising and evaluating key bushfire risks; Identifying mitigation strategies to address the risk to existing, as well as the progressive expansion of the future urban interface in the short, medium and long term growth options, and Page 6 of 55

7 2 Methodology 2.1 Study approach Risk assessment involves consideration of the credible consequences of a hazard and the likelihood of those consequences being realised (EMA, 2010). Planning Practice Note 64 - Local Planning for Bushfire Protection (DTPLI, 2013) provides some guidance about assessing the bushfire risk in relation to land use planning decisions and incorporating risk mitigation measures in future development. The general approach described in Appendix 1 of Planning Practice Note 64 has been used to structure this bushfire risk assessment for the Wangaratta growth areas. This includes four main steps: Establish the context; Identify the risks from bushfire; Analyse and evaluate the risks; and Translate risk mitigation into planning scheme provisions (DTPLI, 2013). Section 3 The context provides factual information about the study sites and the surrounding landscape. This includes descriptions of the sites, development plans, land use planning controls and bushfire mitigation plans relevant to the growth areas. Map 1. Overview of the two growth areas identified in the Strategy Section 4 The risk from bushfire, gives details of the factors that influence fire behaviour and how they contribute to bushfire impact on the community. In the context of describing the risk of bushfire to the identified growth areas and the existing Page 7 of 55

8 Wangaratta urban area, the consequence can be defined as loss of life and houses during a bushfire. The likelihood of this consequence can be assessed by considering: The probability of weather conditions occurring that could result in a fire of sufficient intensity to destroy homes and claim lives; The probability of an ignition on that day; The potential for a fire to develop to a level of severity at the study site such that homes are destroyed and lives could be lost; The vulnerability of assets to the level of bushfire attack to which they are exposed; and The presence and efficacy of risk controls. In this assessment a description of potential bushfire behaviour was used to examine the potential for a severe fire to impact the study areas. This description considered a range of inputs, some of which were site-specific data analysed at a local scale (such as fuel, vegetation, topography and length of fire run) and others which were assumptions (such as the weather conditions that might occur on the day of the hypothetical fire, and that an ignition could occur). The description of the bushfire characteristics and potential bushfire scenarios at the study sites was based on: Analysis of spatial and other data provided by the Rural City of Wangaratta or obtained from the State Government of Victoria and other government agencies; Field inspection and assessment of the study area; and The professional judgment of Terramatrix. Section 5 Analysis and evaluation of the bushfire risk to the growth areas provides a summary of the bushfire risk facing the sites and the proposed residential expansion into them. The professional opinion of Terramatrix as to the appropriateness of the proposed development on the sites, given the level off bushfire risk is provided. The ability of the development to comply with the requirements of AS Construction of Buildings in Bushfire Prone Areas (Standards Australia, 2009) (hereafter AS3959) across the sites was considered, as well as the ease with which other appropriate bushfire risk mitigation measures could be implemented. The Planning and design response explains how the bushfire risk mitigation measures could be included in the expansion of Wangaratta. The following design principles were used as a basis for these measures: Avoid residential development in higher risk areas and provide appropriate setbacks from classified vegetation; Consolidate the township edge to limit grass/bushfire spread into the town area; Reduce the impact of bushfire on the new subdivisions and adjacent existing urban areas and by providing appropriate defendable space, promoting fire- safe landscape design within the residential area, and constructing new dwellings to the appropriate BAL construction standard; Page 8 of 55

9 Facilitate effective fire suppression through urban design that meets CFA requirements for access and water supplies; and Provide viable evacuation and/or shelter-in-place options for residents and visitors. The Royal Commission (VBRC, 2010) and Clause Bushfire of the Victoria Planning Provisions (Wangaratta Planning Scheme, 2011) advocate applying the precautionary principle to assessing bushfire risk in new development, and this philosophy has guided the analysis and making of recommendations in this study. 2.2 Document review The following documents were reviewed as part of this study: Rural City of Wangaratta Population and Housing Strategy (RCOW, 2013) Hume Region Regional Bushfire Planning Assessment (DPCD, 2012) Rural City of Wangaratta Municipal Fire Management Plan (RCOW, 2013) Fire Operations Plan 2013/ /16 - Hume Region (DEPI, 2013) Community Information Guides Bushfire for Glenrowan-Hamilton Park and Eldorado (RCOW and CFA, 2011) Rural City of Wangaratta Roadside Management Strategy (Kunert, 2000) Page 9 of 55

10 3 The context 3.1 Site overview Wangaratta is a regional city with a population of 17,000 residents, in north-east Victoria (RCOW, 2013). It is located approximately 60 km south west of Albury-Wodonga and more than 200 km north-north-east of Melbourne. The Hume Freeway skirts the south-east of town and the Melbourne- Sydney railway passes through its middle. Wangaratta is a major regional centre, offering key services to the broader King and Ovens Valley communities. The town centre lies on the western bank at the confluence of the King and Ovens Rivers. The suburban areas of the town spread outwards from the town centre, but are generally confined to the west of the rivers. The Warby Ovens National Park is approximately 5km further west from the western-most edge of the Wangaratta urban area. ha west of Reith Road) has been identified for long-term residential growth (Refer Map 2). The other area is to the south of Wangaratta. This is a smaller area of 77 ha which has been identified for short to medium term growth. This site is referred to as the southern growth area in this report. Greta Road, Salisbury Street and Clarkes Lane bound this site, while other edges of the site are defined by the current extent of land zoned as Farming Zone (Refer Map 3). There are two study sites for this project. These areas were identified in the Strategy as potential areas for greenfield residential growth. One is to the west and north-west of Wangaratta, with a total area of 735 ha. It is referred to as the western growth area in this report. It is bounded by Warby Range Rd, Old School Rd, Reith Rd, Wangandary Rd, Christensen Ln, Lindner Rd, Worland Rd, Bella Way, Three Mile Creek and the northern boundary of the Rural Living Zone properties on Colson Dve. The eastern portion of this area (215 ha east of Reith Road) has been identified with for short to medium term residential growth, while the western portion (520 Page 10 of 55

11 Map 2. Overview of the western growth area at Wangaratta Map 3. Overview of the southern growth area at Wangaratta Page 11 of 55

12 3.2 Landscape context The broader landscape (1km, 10km and 20km) around Wangaratta was considered as per the advice of Planning Note 64 (DTPLI, 2013) (Refer Map 4). The dry-land agriculture is a major land use in this broader area in all directions. It extends hundreds of kilometres to the north and west. A band of floodplain forest stretches north-west to south-east at the northern boundary of Wangaratta, delineating the course and primary flood plain of the Ovens River. The Warby Ranges are also a significant feature to the west of Wangaratta. Native forest and woodland cover these hills. This broader landscape is inherently fire prone, and large bushfires are credible under fire weather conditions. A 150 m assessment zone, beyond each site boundary, was applied to assess the factors that directly contribute to the behaviour and potential impact of a grassfire or bushfire directly affecting each site. The 150 m assessment area is in accord with the BMO site assessment process (DTPLI, 2011 and CFA, 2012). Under AS3959 the site assessment area is 100m from the proposed dwelling site. A 150m zone was applied here because it reflects the more thorough of the two methods. Map 4. The Wangaratta growth areas and the broader landscape. Page 12 of 55

13 3.3 Existing and future uses Currently both sites are primarily utilised for agriculture. Broad grassy paddocks with few trees are typical. There is some improved pasture and livestock grazing. Some ungrazed paddocks have longer grass. Some minor tree crops were noted (olives) but no cereal crops were observed during the site inspection. There are numerous dwellings scattered through this agricultural land. These houses are often single storey with large garden surrounds. Native trees are clustered along roadsides, fence lines and occasionally in paddocks. Generally the understorey consists of grass, the length of which depends on the presence or absence of grazing. The Strategy indicates that considerable change is planned for the sites. Recent housing development has been occurring on land already zoned Residential 1 adjacent to the sites. The Strategy indicates that when the current supply of land for residential development is exhausted, it is intended that development will expand into the sites. The forecast lot yields in the sites are provided in Table 1. Table 1. Lot yields of the study sites (Aurecon, 2013) Site Approximate lot yield West (eastern portion) 1290 West (western portion) 3120 South 462 The average residential lot size planned for both greenfield sites is 600m 2. However the Strategy advocates for diversity in lot sizes and subsequent housing types. The lot sizes will fall into three classes for: medium density housing (<500 m 2 ) compact housing ( m 2 ) detached housing (>600 m 2 ) (Aurecon, 2013) The Strategy also mentions that there may be provision for some low-density residential zoning, especially upon the outer boundaries of the western growth area. Road upgrades and improved community infrastructure would also be expected within the new sites as a part of development. 3.4 Fire history Fire history data is informative in assessing bushfire risk. The frequency and consequence of past fires may be indicative of future fire frequency and consequences. The DEPI fire history map layer (DEPI, 2014) contains records of wildfires and planned burns since 1970, mostly on public land. There have been multiple fires in the past near Wangaratta, including several in the Warby Ranges (Refer Map 5) that are less than 15 km from Wangaratta. Other evidence of fires near Wangaratta exists in other sources. Of particular note are the descriptions of major fire seasons in Victoria by Luke and McArthur (1978). The fire season was a major grassfire season with an estimated 1 million Page 13 of 55

14 hectares burnt in the state. In December 1943 ten people died in a large fire near Wangaratta. The fire season was also noted to contain extreme fire weather in north-eastern Victoria. On 5 February 1952 a fire near Benalla burnt about 100,000 ha and killed several people. A locally significant grass fire has also occurred in the area bounded by the southern growth area in the vicinity of Clarks and Wenhams Lane (J McCaffrey, pers. comm., 12 June 2014). impacting the major settlement of Wangaratta is listed as a risk with ID 3 (Refer Table 2). A table of Fire Management Risk Strategies within the MFMP lists many treatments to reduce the risks listed in the register. Several treatments relate to the risk of bushfire impacting Wangaratta. Council have some responsibility for many treatments including fuel management on private land and some roadsides. Map 5. Bushfires recorded around Wangaratta (DEPI, 2014) 3.5 Municipal Fire Management Plan The Municipal Fire Management Plan (MFMP) includes a register of risks associated with bushfire impact. A bushfire Table 2. Extract from the Wangaratta MFMP Risk Register (p. 29) Rural City Of Wangaratta Bushfire Risk Register ID Risk Description Cause Impact Risk of Wangaratta being impacted by Lightning, Loss of life, injury, bush- fire (or agricultural loss of houses, associated ember machinery, economic, 3 attack) from the SW misuse of fire to infrastructure, in the Warby Ranges north and west transport under Extreme side of ranges interruption plus FDR conditions. Extracts from the Municipal Fire Prevention Strategy are also included in the MFMP, which provide specific details of the fuel management Council has completed in the past. A number of the roads in and around the study sites are nominated as Fuel Reduced Corridors or Priority Access Roads and listed for fuel Page 14 of 55

15 management works (Refer Table 3). Specific guidance regarding fuel management on private properties is also provided. The MFMP also notes that based on current trends and the impact of climate change, research modelling suggests the future climate will be both warmer and drier. It is expected there will be an increase in the number of extreme fire danger days as well as longer fire seasons. Road Name Fuel Growth reduced area corridor Priority access road Bella Way West Greta Road South Salisbury Street South Clarkes Lane South Table 3. The roads associated with the study sites and their status within the MFMP. Road Name Warby Range Road Old School Road Growth area West Fuel reduced corridor Priority access road Drive) West Reith Road West Wangandary Road Christensen Lane (between Lindner Road & Shanley Street) West West Lindner Road West Worland Road West 3.6 Community Information Guide Bushfire There is no Community Information Guide - Bushfire for Wangaratta. Wangaratta is, however, mentioned as a destination in other Community Information Guides, as it is away from higher risk communities (such as Eldorado and Glenrowan-Hamilton Park) and people may consider seeking safety from bushfire there. 3.7 Local fire suppression resources Wangaratta lies in CFA District 23, within the Hume Region. Central Wangaratta is home to the district headquarters with the Wangaratta fire brigade adjacent. This would be the closest large fire station to both growth areas. Several hamlets outside of central Wangaratta also havel CFA volunteer brigades. Wangaratta South is the closest of these to the growth areas. The Wangaratta South Station is located on Shanley Street at the intersection of Warby Range Road. This brigade is well placed Page 15 of 55

16 to offer suppression to the growth areas, particularly the western area. 3.8 DEPI Fire Operations Plan Wangaratta, the Warby Ranges and the land to the west fall into the DEPI Goulburn District of the Hume Region. The Fire Operations Plan 2013/ /16 - Hume Region contains a list of fire management works planned for public land within the Goulburn District. There are several works planned for near Wangaratta and within the Warby Ranges. Several of the works are for ecological reasons, but there are two sizable fuel reduction burns scheduled. One is a 204 ha burn at Mt Killawarra and the other is the 606 ha Boweya Track burn. These are both within the Warby Ranges. The works nearer to Wangaratta are minor. 3.9 Access and egress Both sites comprise large parcels of land and a grid of roads that run in a general north-south or east-west orientation. Most of the major roads are through roads that offer access and egress in both directions. As the roads are currently in a rural environment and some are narrow and/or unsealed, some upgrade is foreseen with residential development. Wangandary Road, Linder Road, Reith Road, Warby Range Road, Christensen Lane and Worland Road form the major road network in the western growth area. Clarkes Lane, Greta Road and Salisbury Street form the major road network for the southern growth area. A secondary road network is emerging with the encroaching urbanisation. These roads are being constructed to provide access to the new residential areas and link in to the larger road network. Section 3.5 in this report provides details of which roads currently in and close to the sites have been nominated as Fuel Reduced Corridors or Priority Access Roads within the MFMP State Planning Policy Framework (SPPF) Clause of the SPPF deals with bushfire. It has the objective of assisting community resilience to bushfire. 'Overarching strategies' to achieve the objective are to prioritise the protection of human life over other policy considerations in planning and decision-making in areas at risk from bushfire, and, where appropriate, to apply the precautionary principle when assessing risk (Wangaratta Planning Scheme, 2011). Clause stipulates development control strategies that only permit new development where: 'The risk to human life, property and community infrastructure from bushfire can be reduced to an acceptable level; Bushfire protection measures, including the siting, design and construction of buildings, vegetation management, water supply and access and egress can be readily implemented and managed within the property; and Page 16 of 55

17 The risk to existing residents, property and community infrastructure from bushfire is not increased' (Wangaratta Planning Scheme, 2011) Regional Bushfire Planning Assessment Several areas relating to the study sites were identified in the Hume Region - Regional Bushfire Planning Assessment (RBPA) (DPCD, 2012) (Refer Table 4). Table 4. Extract from Wangaratta Identified area description table, RBPA, Hume Region Code Location Identified Area Description Peechelba, Killawarra, Wangandary and Wangarratta South Wangaratta Wangaratta South Development pressure is being experienced extending from Peechelba, Killawarra, Wangandary and Wangaratta South, to the north and west of the Wangaratta township towards the Warby Ranges and associated bushfire hazard area. Riparian corridors following creek alignments in Wangaratta settlement are known bushfire hazards. Single constructed road (Shanley Street) extending east from Cox Road, servicing cluster of dwellings. Code Location Identified Area Description Single constructed road extending south-east Wangandary (Wangandary Road) servicing dwellings and area experiencing development pressure Waldara Wangaratta Planning Scheme provides for extension of the Wangaratta township around Waldara. This area is in proximity to a bushfire hazard area Planning zones The land use planning zones within and surrounding each study site are shown in Map 6. The settlement patterns and fuel character of each existing zone are described and the implications of this for fire impact are also described. Page 17 of 55

18 Map 6. Land use planning zones within and surrounding the western growth area Map 7. Land use planning zones within and surrounding the southern growth area Page 18 of 55

19 Farming Zone (FZ) The FZ is the main zone that applies to both sites. This zone represents a history of agricultural land use. The prime purpose of FZ is to provide for the retention and use of land for agriculture, and a minimum 40 hectare lot size applies for subdivision (Wangaratta Planning Scheme, 2013). The Strategy recommends that Development Plan Overlays be applied on both sites as part of any greenfield residential expansion. Furthermore the Strategy implies that as a result of future urbanisation, these sites would be rezoned for residential proposes and community infrastructure. Land adjacent to both sites would, however, remain in Farming Zone, for the foreseeable future. The typical land uses in Farming Zone of cropping and animal grazing offer little obstacle to the spread of wildfire. Intensive grazing or timely ploughing can temporarily reduce the fuels in this zone, but the implementation is not assured. Thus it should be expected that a large fast moving grassfire could spread through Farming Zone and impact the edge of the urban area Rural Living Zone - Schedule 1 (RLZ1) The RLZ1 provides for residential use in a rural environment and appropriate agricultural uses, with an emphasis on sustainable land management. The minimum lot size for subdivision is 2 hectares (Wangaratta Planning Scheme, 2008). This zoning applies to an area immediately to the south of the long-term western growth area. The properties on Colson Drive are an example of a rural living area, with each property being approximately 2 hectares. Large family houses, large gardens and animal husbandry typify this type of development. Houses are surrounded by grassy environments, and often fence lines and garden areas are planted with trees. The degree of penetration by bushfire into this type of development is very reliant on the amount of vegetation management in the gardens and paddock areas of the private properties. A large grassfire occurring on a day of elevated fire danger could easily penetrate into and through this type of development. Some reduction in flame height is likely due to mowing and/or grazing. Some fragmenting of the fire edge may occur due to discontinuous fuels and suppression efforts Low Density Residential Zone (LDRZ) This zone provides low-density residential areas where there is an absence of reticulated sewage. The minimum lot size in this zone is 1 ha (Wangaratta Planning Scheme, 2006). Agriculture, other than keeping two or fewer animals, requires a permit. The development to the north of the western growth area at Waldara is an example of this zone. Large family houses with large gardens typify the area, however the density of housing is higher than Rural Living Zone. A large developed grassfire may impact the fringe of this development, but as most properties are completely maintained as park-like gardens and there is Page 19 of 55

20 reasonably intensive road network, fire penetration would generally be more fragmented than in the RLZ Residential 1 Zone (R1Z) This zone is the primary residential zone that applies to the most of the residential areas of Wangaratta. This zone abuts both sites and is the major zone that would result from any rezoning of both growth areas. This zone primarily provides areas for a range of housing types to service the community. Some community buildings may also be located in this zone. The Strategy recommends an average lot size of 600m 2 for the new greenfield residential development. The housing density associated with this average lot size and resulting garden areas would mean that once developed the growth areas would be highly modified and have very limited hazardous vegetation distribution. A bushfire is likely to impact the interface areas of developed parts of this zone but have very limited penetration into the urban area, other than ember attack and small spot fires Commercial 2 Zone (B4Z) This zone offers areas for commercial uses such as offices, manufacturing, industry, warehousing, and retailing. An area of this zone is immediately to the north of the southern growth area. While not yet used as per this zone, once developed as a shopping precinct as indicated by the Strategy, it is anticipated that the area would of negligible bushfire hazard Road Zones (RDZ1 and RDZ2) These areas recognise the importance of existing or proposed road corridors in providing movement and accessibility within the landscape. Wangandary Road (passing through the western growth area) and Greta Road (adjacent to the southern growth area) lie in this zone. Roads and tracks are generally fuel free areas thereby acting as a fuel break, while they are also critically important for providing access for fire suppression and routes for evacuation from bushfire threat. Fuel management on the side of roads can enhance the ability of a road to offer these benefits, although it is rarely possible to make a rural road safe to travel during the passage of the fire front by management of the road reserve alone. Retention of native vegetation is however often an important function of these corridors. A balance between vegetation management for fire risk reduction and flora and fauna purposes is necessary. There is currently no Vegetation Protection Overlay (VPO) covering any of the vegetation on or close to either of the sites, including in these road reserves Public Park and Recreation Zone (PPRZ) PPRZ provides areas for public recreation and open space and can also help to protect and conserve areas of significance. The watercourses on the eastern boundaries of both study sites have riparian strips that contain remnant native vegetation. Narrow bands of this zone cover some of this riparian area. The degree of bushfire hazard or protection these areas offer to the Page 20 of 55

21 surrounding community into the future will be very much dependant on the management of vegetation within them, particularly any mowing of the understorey. Access for emergency services should also a key consideration. Examples of PPRZ creek reserves that exhibit appropriate vegetation management for fire risk reduction purposes currently exist further north on both these watercourses, within the existing urban area Planning overlays minimise risks to life and property. Works are restricted in these overlays. These overlays are the only overlays that currently cover either of the study sites. The location of these overlays is associated with the watercourses that exist on the eastern boundary of both sites. The implication of this overlay for bushfire risk at either site is limited despite native vegetation retention being important in the creek corridors. Overlays relevant to the sites are shown in Map 8 and Map Bushfire Management Overlay (WMO or BMO) The purpose of this overlay is to protect life and property from bushfire impact by applying a number of development controls. It is implemented in areas where the bushfire risk is high due to hazardous bushfire characteristics such as steep slopes and forests. Neither the current BMO or draft BMO covers any part of either of the study sites. Areas within the Warby Ranges and in proximity to other areas of forest and woodland in the broader landscape are within the current and draft BMO Floodway Overlay (FO) and Land Subject to Inundation Overlay (LSIO) The flood and inundation overlays exist where there is a risk of being in a floodway or on the fringes of flooding. The purpose of these overlays are to maintain the health of waterways and Page 21 of 55

22 Map 8. Land use planning overlays within and surrounding the western growth area. Map 9. Land use planning overlays within and surrounding the southern growth area. Page 22 of 55

23 3.14 Bushfire Prone Area (BPA) Both study sites are entirely within a designated Bushfire Prone Area (BPA) (Refer Map 10 and Map 11) BPAs are those areas subject to or likely to be subject to bushfires, as determined by the Minister for Planning. Interestingly the edge of the BPA currently lies very close to the site boundaries. In relation to the western growth area, some of the recent development near Williams Road is not covered by the BPA. Likewise, the urban area to the north of the southern growth area is not covered. The Building Regulations 2006, through application of the Building Code of Australia, apply bushfire protection standards for building works in designated BPAs. A minimum construction standard applies to all new buildings in a BPA. Buildings must be constructed to a minimum Bushfire Attack Level (BAL) of 12.5, or higher as determined by a site assessment or planning scheme requirement. A BAL is a means of measuring the severity of a building s potential exposure to ember attack, radiant heat and direct flame contact. There are six BALs that form part of AS3959. The level of risk and expected fire outcomes at each BAL are explained in Table 5. Map 10. Coverage of the BPA across the western growth area. Page 23 of 55

24 Map 11. Coverage of the BPA across the southern growth area. Page 24 of 55

25 Table 5 - Bushfire Attack Levels (BALs) explained (Standards, Australia, 2009). Bushfire Attack Level (BAL) BAL-Low BAL-12.5 BAL-19 BAL-29 BAL-40 BAL- FZ (i.e. Flame Zone) Risk Level VERY LOW: There is insufficient risk to warrant any specific construction requirements but there is still some risk. LOW: There is risk of ember attack. MODERATE: There is a risk of ember attack and burning debris ignited by windborne embers and a likelihood of exposure to radiant heat. HIGH: There is an increased risk of ember attack and burning debris ignited by windborne embers and a likelihood of exposure to an increased level of radiant heat. VERY HIGH: There is a much increased risk of ember attack and burning debris ignited by windborne embers, a likelihood of exposure to a high level of radiant heat and some likelihood of direct exposure to flames from the fire front. EXTREME: There is an extremely high risk of ember attack and a likelihood of exposure to an extreme level of radiant heat and direct exposure to flames from the fire front. Construction elements are expected to be exposed to Comment No specification. At 4kW/m 2 pain to humans after 10 to 20 seconds exposure. Critical conditions at 10kW/m 2 and pain to humans after 3 seconds. Considered to be life threatening after 1 minute exposure in protective equipment. A radiant heat flux not greater than 12.5 kw/m 2 A radiant heat flux not greater than 19 kw/m 2 A radiant heat flux not greater than 29 kw/m 2 A radiant heat flux not greater than 40 kw/m 2 A radiant heat flux greater than 40 kw/m 2 At 12.5kW/m 2 standard float glass could fail and some timbers can ignite with prolonged exposure and piloted ignition. At 19kW/m 2 screened float glass could fail. At 29kW/m 2 ignition of most timbers without piloted ignition after 3 minutes exposure. Toughened glass could fail. At 42kW/m 2 ignition of cotton fabric after 5 seconds exposure (without piloted ignition). At 45kW/m 2 ignition of timber in 20 seconds (without piloted ignition). Page 25 of 55

26 4 The risk from bushfire This section articulates the potential risk of bushfire impact at both the western and southern Wangaratta growth areas. The three factors (fuel, topography and weather, refer Figure 1) influencing bushfire behaviour were characterised for each site and the broader landscape. Based on these factors, each site was described in terms of the CFA landscape risk scenario it best accorded with. This information was utilised in the development of a description of potential major bushfire impact scenarios for the sites. The potential impacts are then discussed in terms of which mechanisms of bushfire attack could be expected across the sites. This section also includes a brief discussion of some other factors that may influence the degree of impact, such as suppression and evacuation. 4.1 Bushfire behaviour Figure 1. Three factors influencing bushfire behaviour Fuel Vegetation growing in a landscape is the primary fuel source for bushfire. Trees, shrubs and grasses store energy from photosynthesis and under the right conditions this energy can be released through combustion. The way plants combust varies depending on the branching habit, biomass, moisture content and chemical composition. Management, location, species and season influence these factors. This section analyses the vegetation within and adjacent to the study sites and determines the contribution this fuel would Page 26 of 55

27 make to fire behaviour. The methodology to assess the fuel in this study has been to; Determine extent of native vegetation present in and near the study sites from DEPI data and mapping; Assign EVCs/native vegetation groups present, to the most applicable AS3959 vegetation groups; Map each AS3959 vegetation classes across the study sites based on EVC mapping, aerial photography interpretation, vegetation coverage mapping and field visits. Whilst large bushfires impacting the study area may develop from significantly greater distances around the study area, their intensity and likely impact on the actual township will correlate more directly with the vegetation within the 150 m assessment zone. Consideration was also given to the potential ember generation from the forest/woodland within the Warby Range Native vegetation Both study sites are within the Victorian Riverina Bioregion. Bioregions are based on ecological patterns and underlying environmental features including landform and vegetation, and reflect natural boundaries (DEPI, 2014b). DEPI mapping identifies five EVCs as being extant in the study sites, representing three sub-groups (refer Map 12, Map 13 and Table 6). These EVCs and their groupings share ecological and structural characteristics. Map 12. Ecological vegetation classes across the western growth area. Page 27 of 55

28 Map 13. Ecological vegetation classes across the southern growth area. Page 28 of 55

29 Table 6 - Native vegetation in the study site 150 m assessment areas by EVC Group, Sub-group, EVC (DEPI, 2014) and corresponding AS3959 vegetation class Ecological Vegetation Class (EVC) AS3959 Bioregion Bioregional Study site Group No. Subgroup No. Group - Sub-group Name Component EVC No. - Name Vegetation Group Conservation Status of relevance Lower Slopes or Hills Woodlands - Grassy EVC Grassy Woodland Woodland Victorian Riverina Endangered Western Plains Woodland or Forests - Poorly draining EVC Plains Woodland Woodland Victorian Riverina Endangered Western Plains Woodland or Forests - Freely draining EVC 55 Plains Grassy Woodland Woodland Victorian Riverina Endangered Southern Plains Woodland or Forests - Freely draining EVC 240 Plains Grassy Woodland /Creekline Grassy Woodland /Wetland Formation Mosaic Woodland Victorian Riverina Endangered Southern Riverine Grassy Woodlands or Forests - Creekline and/or swampy EVC 68 - Creekline Grassy Woodland Woodland/ Forest Victorian Riverina Endangered Western and Southern Page 29 of 55

30 AS3959 classified vegetation AS3959 uses a vegetation classification system to determine the fire behaviour models to be applied in predicting the level of bushfire attack. The seven broad vegetation classes used within AS3959 (Standards Australia, 2009) to determine the requisite BAL and defendable space distances are shown in Table 7. The EVC benchmark information can be a useful indicator of likely fuel load and arrangement, from which the most appropriate AS3959 classifications can be decided. Table 7. The vegetation classes used in AS3959 for determining fire behaviour. Vegetation classes in AS3959 A. Forest B. Woodland C. Shrubland D. Scrub E. Mallee/Mulga F. Rainforest G. Grassland The classification system does not directly align to Ecological Vegetation Classes (EVCs) but uses a generalised description of vegetation based on the AUSLIG (Australian Natural Resources Atlas: No. 7 - Native Vegetation) classification system. Under the AS3959 site assessment methodology if more than one vegetation type is present within 150 m of an application site the worst case scenario is applied - the predominant vegetation type present is not necessarily the worst-case scenario (Standards Australia, 2009). Based on the mature height and canopy cover of overstorey vegetation (as prescribed in the relevant EVC/Bioregion Benchmark for Vegetation Quality Assessment,) and the amount of elevated fuel, each EVC was assigned to the most appropriate AS3959 vegetation class. Each vegetation type is assigned a default fuel load by AS3959. The amount of fuel is of major importance to fire behaviour. The more fuel the more intense the fire (if fuel load is doubled then fire intensity increases fourfold (Noble et al., 1980)). Fine fuels such as leaves, twigs and bark, make a much greater contribution to bushfire behaviour than coarse fuels (Hines et al, 2010). Fine fuels dry faster and combust faster. Coarse fuels influence the duration of the fire activity as tree trunk and logs can continue burning for long periods after the fire front has passed. The Overall Fuel Hazard Assessment Guide (Hines et al, 2010) is a tool for quantifying the fuel hazard rating and amount of fine fuel available for bushfire. The guide provides a method to reach an overall fuel hazard rating. Indicative fuel loads, measured in tonnes per hectare, can be inferred from the fuel hazard ratings. Different vegetation communities grow and accumulate biomass differently. In general, a plant community will accumulate biomass rapidly after a disturbance, such as bushfire. After a period, generally a number of years, the amount of biomass reaches equilibrium where growth and deposition of litter Page 30 of 55

31 roughly equal the rate of decomposition. This is known as the quasi-steady state fuel load. The quasi-steady state fuel loads differ between vegetation communities. In more productive forest sites, where there is an abundance of nutrients, the maximum fuel load may exceed 35 t/ha (Tolhurst, 2009). In more limited sites the maximum quasi-steady state fuel loads are lower. AS3959 considers the differences in fuel amount between different vegetation communities by assigning a quasisteady state fuel loads to each of the seven vegetation classes. The steady state surface fuel load represents the maximum likely to accumulate if the vegetation is long undisturbed. AS3959 uses a grassland fire behaviour model to predict fire behaviour in all open vegetation forms where the foliage cover of the overstorey is less than 10%. This includes native grasslands, pastures and herbfields. The requisite defendable space for grassland is calculated with a fuel load of 4.5 t/ha (Standards Australia, 2009). Low threat vegetation and non-vegetated areas can be excluded from classification due to size and separation of fuel patch and fuel type, as per Section of AS3959 (Standards Australia, 2009). AS3959 defines forest as trees greater than 10 m in height with foliage cover of 30-70%. This includes native forests with an established understorey (ranging from large shrubs, to ferns, to grasses) and plantations (Standards Australia, 2009). The requisite defendable space for forest is calculated for a surface fine fuel load of 25 t/ha and an overall fine fuel load of 35 t/ha (Standards Australia, 2009). AS3959 defines woodland as containing trees of any height and with a canopy cover of between 10% and 30% (Standards Australia, 2009). The understorey of woodland can range from containing low trees and tall shurbs to low shurbs and grasses. The requisite defendable space for woodland is calculated for a surface fine fuel load of 15 t/ha and an overall fine fuel load of 25 t/ha (Standards Australia, 2009). Table 6 indicates the most appropriate AS3959 vegetation class for each EVC, assuming that the EVC benchmark is met The fuel at the Wangaratta growth areas In the case of the Wangaratta growth areas, site inspection and aerial photography interpretation revealed that the density of tree canopy across the sites was much lower than the EVC benchmark (Refer Figure 2). In general the extent of native vegetation did not appear as broad as indicated by the DEPI EVC mapping. Terramatrix therefore classified the majority of both sites and 150 m buffers as being covered by the AS3959 vegetation class of grassland. An area of woodland was classified along Three Mile Creek at the eastern edge of the western Wangaratta growth area. The remaining areas were mapped as low-threat areas as they were close to existing houses or other buildings and appeared to be landscapes Page 31 of 55

32 modified to be gardens or park-like. An assumption with the mapped extent of these low threat areas is that that are maintained in a low-threat state at the time of fire impact. The corresponding AS3959 vegetation classes for the two Wangaratta sites are shown in Map 14 and Map 15. Figure 2. Typical view into grassy paddocks within the western growth area. Map 14. AS3959 vegetation classes across the western growth area. Page 32 of 55

33 4.1.2 Weather A number of assumptions about weather conditions underlie the AS3959 modelling of bushfire impact. The key assumption is a Grass Fire Danger Index (GFDI) of 130 when modelling impacts from grassfire. This presumption represents a 'one size fits all' model of extreme grassfire weather conditions and is not necessarily the worst-case conditions for any particular location. This section examines the applicability of this presumption of GFDI 130 for Wangaratta. The analysis is based on Bureau of Meteorology (BOM) data from the Automatic Weather Station at Wangaratta Aero Club and three next closest AWSs to the sites (Rutherglen, Yarrawonga and Shepparton) where the parameters needed to calculate GFDI (temperature, relative humidity and wind speed) are recorded (Refer Table 8). Map 15. AS3959 vegetation classes across the southern growth area. Table 8. Automatic weather stations used to assess GFDIs for Wangaratta Distance and GFDI parameter record Station Name direction from period sites 3.5 km south from southern growth Wangaratta area present Aero 7.2 km south-west from western growth area Page 33 of 55

34 Station Name Distance and GFDI parameter record direction from period sites mid 1970s present Rutherglen 33 km north-east (limited parameters Research recorded since 1913) Yarrawonga 44 km north-west present Shepparton Airport 82 km west present GFDI was calculated for every half hourly entry at each of these stations with the available data. Curing was assumed to be at its maximum value (100%). The frequency of elevated GFDIs was then examined and characterised (Refer Figure 3). The highest GFDI recorded at Wangaratta Aero Club AWS is 143. This was recorded at 2.30 pm on Black Saturday (7/2/2009) with a temperature of 44.1 C, relative humidity of 6% and a wind speed of 44 km/h. Other instances of GFDIs in excess of 130 were recorded at other stations; one instance at Shepparton (20/11/2009) and two instances at Yarrawonga (21/12/2005 and 12/01/2010). Interestingly Wangaratta was the only station among the four, where the GFDI exceeded 130 on Black Saturday. Figure 3 - Records of GFDI 100 at Wangaratta and other AWS The analysis demonstrates that within the records spanning 26 fire seasons there was one instance of a GFDI above 130 in the general Wangaratta area. While the longevity of records does not permit an accurate return interval to be calculated, the single example provides support for the case that a GFDI exceeding 130 is likely to occur again within the life of the development. An argument could be made to vary the AS3959 default weather conditions in several regions of Victoria (e.g. it may be excessive in the Alpine area or at coastal locations, and is likely to be exceeded on rare occasions in most inland areas), but it must be Page 34 of 55

35 recognised that the default values do not necessarily represent actual worst case bushfire weather conditions for a site, but rather a benchmark standard, representative of extreme bushfire weather for the whole state. corresponds to fire danger ratings of Severe (FF50-75), Extreme (75-100) or Catastrophic (Code Red) (100+) Terramatrix believes it is more appropriately a question of state policy for DTPLI and the Building Commission to depart from the standard 130 GFDI for a wider area or region Wind Wind has a significant effect on the rate of spread of a bushfire, particularly a grassfire where it is the most dynamic influence affecting fire behaviour (Cheney and Sullivan, 2008; Long, 2006). The AWS records provide wind speed and direction data. The wind direction associated with high fire danger weather events was examined at Wangaratta. The Forest Fire Danger Index (FFDI) is an index similar to GFDI with a strong correlation between GFDI and FFDI. Fire authorities provide fire danger warnings by using the forecast FFDI. A GFDI of 130 generally translates to a FFDI of about 100. For the wind direction analysis FFDI was used. The maximum FFDI result was found for a wind direction from each point of the compass. These FFDIs were then plotted on a circular graph (Figure 4). Higher FFDIs are represented by longer lines. Blue lines are FFDIs under 50. This corresponds to a fire danger rating of high or less. Red lines are for FFDIs equal to or greater than 50. This Figure 4. The highest recorded FFDI associated with each point of the compass. There is a clear trend at Wangaratta for the wind direction during elevated fire danger events to be from the western side of the compass. When the FFDI exceeded 80, these wind direction was confined to a 90 degree portion of the compass (between 250 and 330 degrees). This is typical of central and north-central Victoria where most extreme fire weather days correspond with north or north-westerly wind flows (Long, 2006). The highest FFDI recorded with a wind direction from anywhere between north-east through to due south (40 to 180 degrees) was a single record of 60 associated with an east-southeast wind. Page 35 of 55

36 4.1.3 Topography Topography is an important consideration in assessing fire risk as the forward rate of spread and hence energy output will increase when a fire spreads uphill and decrease when spreading downhill. A well accepted rule of thumb is that for every 10-degree increase in slope the forward rate of spread will double. AS3959 considers classes of slope under classified vegetation and together the type of vegetation and the steepness in relation to the site will determine the requisite vegetation setback. The topography immediately in and around Wangaratta is typical of the wide riverine valleys of north-eastern Victoria. The sites themselves are generally flat to very gently sloped. The gentle slopes in the growth areas are generally upslopes or flat (along the contour), assuming a fire approach from the western half of the compass. A slight uphill rise may be found in places due to small peaks and rises. The actual slope on such sites is generally less than 1 degree. The gentle and scarce nature of these downslope areas leads Terramatrix to conclude that their affect on fire behaviour will be negligible. Map 16. Topography of the Wangaratta growth area and surrounds. Page 36 of 55

37 4.2 CFA landscape scenarios To assist in defining situations where achieving compliance with the bushfire planning and construction standards may be challenging, CFA have described four 'landscape scenarios', representing different risk levels, in the publication Planning for Bushfire Victoria: Guidelines for Meeting Victoria s Bushfire Planning Requirements (CFA, 2012) (refer Figure 5). These four scenarios range from an extreme risk landscape where development is unlikely to be appropriate to a lower risk, more urbanised site where 'default' bushfire protection measures in the BMO may be able to be modified whilst still providing an acceptable degree of safety. It is considered that both of the Wangaratta growth area sites and surrounding land best accords with one of the two intermediate risk landscapes, namely 'Scenario A', described as: Landscape Scenario A 'A landscape consistent with the assumptions in AS A steady state rate of spread is likely to be achieved. However, the fire is unlikely to expose the development to severe convective winds. The planning provisions accommodate for this type of landscape' (CFA, 2012). Page 37 of 55 Figure 5 - CFA Landscape Risk Scenarios (CFA, 2012)

38 4.3 Potential major bushfire scenarios Most of south-eastern Australia has the climatic and geographic factors that make the landscape fire prone. The landscape around Wangaratta is no exception. Although the vegetation occupying the landscape has been altered from a predominant woodland structure prior to European occupation, the current vegetation types of unirrigated grassy paddocks, with isolated clusters of trees, would be capable of carrying a large fast moving grassfire under the right weather conditions. The wooded hills of the Warby Ranges to the east of Wangaratta, with remnant native forest and woodland and rugged topography is an area where a bushfire could establish before spreading towards Wangaratta as a grass fire. The typical fire weather patterns of inland Victoria consist of strong, hot and dry winds from the north and north-west followed by a strong south-westerly wind change. The western growth area, jutting out from the western extent of the existing urban area, will have an interface with non-urban grassy fuels on three faces (north west, west and south), and could be impacted by a fire approaching from all directions from north to south, through west, meaning that it could be impacted under the influence of typical fire weather occurring both before and after a wind change. One example of a fire impacting the western growth area could be a well-established grassfire spreading towards Wangaratta from near Killawarra under the influence of north westerly wind. Another example could be a fire that started within the Warby Ranges, or in the agricultural land beyond the ranges to the west, which becomes a wellestablished fire while under the influence of a northerly or north-westerly with then the eastern flank then spreading towards the growth area following a wind change. As the southern growth area is to the south of the existing urban area, it would be relatively sheltered from any fire spreading under a direct northerly influence. However, it does have grassland interface on its western and southern faces, meaning that a more likely impact is from a fire that is spreading towards Wangaratta from these directions as might occur following a south-westerly wind change. This scenario could correspond to a fire that started somewhere in the southerly end of the Warby Ranges and then spreads into the grassy valley country when exiting the forest. An approach from the east is less likely, as easterly winds rarely correlate with fire weather conditions, but in the unlikely even it occurred the southern growth area may also then be impacted. The behaviour of any such fire would be expected to be less extreme than a fire in accordance with the other scenarios. Any wildfire impact on the growth areas would be from grassfire as the areas of forest that may burn during the same event are located at least 5 km from the growth areas. Longrange ember travel from forest fires has been recorded as starting spot fires multiple kilometres from the main fire front, Page 38 of 55

39 however severe ember attack would not be expected at the study sites due to their distance from large treed areas. Grassfires are characterised by high forward rates of spread, which means they can impact with little warning. While grassfires are less intense than forest fires, their speed and radiant heat under extreme conditions can be fatal, and widespread house loss is feasible. Major grassfires have caused considerable damage and loss of life across Victoria in the past (e.g. Maynes and Garvey, 1985; McArthur et al. 1977). House loss has occurred from grassfires burning into residential estates under development on the urban fringe (e.g. Melton 1985 Maynes and Garvey, 1985; and Narre Warren 2009 VBRC, 2010). 4.4 Potential bushfire impacts Mechanisms of bushfire attack The mechanisms of bushfire attack on a building can be a combination of sparks and embers and/or direct flame contact and/or radiant heat (Refer Table 6). Strong winds may also cause structural damage to a building and increase the chances of ignition by embers, radiant heat or flame. Figure 6 - Mechanisms of bushfire attack on a building Ember attack Ember attack is the most common cause of house loss during bushfires. Ember attack occurs when small burning twigs, leaves and bark are carried by the wind, and land on and around the building. If they land on combustible surfaces they can cause an ignition that can engulf the whole building. Embers can enter gaps as small as 1.8 millimetres (CFA, 2012). Typically, ember attack can be expected to commence before a fire front arrives, peak with the passage of the fire front and then continue for a number of hours after the fire front has passed as nearby trees continue to smoulder and shed burning bark. It is important to note that many buildings are lost in the period after the fire front has passed. Page 39 of 55

40 As the dominant vegetation types are generally grassy and without significant amounts of trees with either substantially fibrous bark or ribbony bark, the level of ember attack expected in a bushfire at the sites is minor across. A fire in the Warby Ranges would produce numerous embers but ember attack is greatest within 100m of the forest and very little occurs more than 700m from the forest (Chen and McAneney, 2010). Since the closest part of the western site to Warby Ranges is more than 1800m distant, the likelihood of ember attack from the Warby Ranges in the study sites is very low. Local ember generation can occur from even isolated trees within a grass fire, and hence the risk of ember ignition of future dwellings cannot be discounted completely. At the southern site, the patch of forest within the Wangaratta Common is in a likely upwind direction from the southern growth area. Due to the absence of spotting bark types and the relative isolation of the common from other bushfire fuel areas, the common is not deemed to increase the risk to the southern growth area. Construction to BAL-12.5, as required throughout the BPA, would offer adequate protection from ember attack from any source in the broader landscape Radiant heat and flame contact Radiant heat is the electromagnetic heat that radiates out in all directions from burning materials. It can cause combustible surfaces to ignite without direct flame or ember contact, crack and break windows and dry out materials ahead of an advancing bushfire, making them more readily combustible (CFA, 2012). Arguably it is flame contact or radiant heat that poses the greatest threat to human survival. These mechanisms can result in rapid involvement of the entire building and cause the building to ignite during the passage of the fire front when in most cases there is no option for people present, other than to shelter within the building. Radiant heat is also the most common cause of death in bushfires (CFA, 2012) typically where people are caught out by the fire front.. The Bushfire Site Assessment process, used when applying AS3959 under the BPA or BMO, determines how close a structure should be located to unmanaged vegetation in order for it to receive less than a certain level of radiant heat (e.g. a building constructed to BAL-19 has been designed to withstand a radiant heat flux of up to 19 kw/m 2 ). This is used to determine the most appropriate combination of defendable space and BAL construction standard for proposed development. Page 40 of 55 At both Wangaratta sites, the setback from unmanaged grassland on flat ground necessary for radiant heat flux, from a

41 large fully developed fire under AS3959 weather conditions, to be below 12.5 kw/m 2 is 19m. This distance directly aligns with the defendable space/setback required for house construction to BAL Wind damage Strong winds have the potential to increase a building s vulnerability to other mechanisms of bushfire attack. Winds associated with a severe bushfire can be extreme and unpredictable particularly in steep and highly variable terrain. Winds and wind effects, including eddy currents and channelling, may also damage dwellings in exposed locations such as on or near ridge lines. Wind can cause failure of the building envelope allowing ember entry onto combustible surfaces. It can cause trees and branches to fall, breaking windows, and damaging roofs. Wind should be taken into account in the location, orientation and design of developments. As both growth areas lie on the fringes of Wangaratta within the broad grassy King and Ovens Rivers flood plains, the conditions that may contribute to exceptionally extreme winds during bushfire are absent. The existing requirements for wind resistance within the building construction standards are deemed to be adequate for any housing built in this environment Other factors influencing the degree of bushfire impact Suppression The Wangaratta and Wangaratta South Fire Brigades are well placed to offer some asset protection at the urban fringe. The contribution of fire services, such as CFA, to reducing overall fire impacts is generally acknowledged but difficult to quantify. It is well understood that direct fire suppression techniques are only successful when weather conditions are less extreme. Emergency management theory discourages a reliance on emergency management authorities for reducing the risk of impact, although protection of assets, with appropriate defendable space and construction level, can be highly effective if fire services are present. The provision of suppression resources should be complementary to a suite of other risk reduction treatments Evacuation Evacuation of people to a low risk area can greatly reduce the impact of a bushfire on a human population and since Black Saturday has been actively encouraged by Victorian fire services. However, property impacts are still possible in any such an event. Although the fringes of Wangaratta would not be labelled high risk areas, people at the very fringes should be encouraged to move to the low-threat inner urban environment before (i.e. on higher risk days) or if safe to do so, during a bushfire (Refer Figure 7). The layout of streets and the continuity of low fuel conditions will be important for ensuring Page 41 of 55

42 that people are able to do this safely. Positioning facilities for vulnerable people, such as the young, old and sick, upon the urban fringe is undesirable. The ability of these people to evacuate may be limited, therefore it is better if such facilities are located well within the urban area rather than near the edge of the grassland. All residents should be aware of the nature of the bushfire risk and encouraged to develop a Bushfire Survival Plan that suits their purposes and situation. The key message from the fire services to 'leave early' on days of higher risk should be supported. bushfire occurs. At the time of construction a house may be able to withstand a certain degree of bushfire attack, but unless the property owner or occupier maintains the structure and an appropriate separation from hazardous vegetation, the level of bushfire resistance offered by the building will diminish. Municipal fire and emergency management strategies may be used to encourage owners and occupiers to maintain their properties. Education, free/subsidised green waste services and enforcement programs may be appropriate tools to avoid poor property maintenance at the fringe of the residential area. Introducing landscaping standards for a subdivision may assist with avoiding encroachment of hazardous vegetation into the residential area. Careful consideration should be given to the location, orientation, linkages and proximity to assets of remnant or re-established vegetation. 5 Analysis and evaluation Figure 7. Grassfire risk at the urban fringe (CFA, 2014) Vegetation management and property maintenance The ongoing management of vegetation and maintenance of buildings is crucial in determining the level of impact, if a The western and southern Wangaratta growth areas, nominated for greenfield residential development within the Strategy, could be impacted by bushfire, since both sites are on the interface between urban and grassy agricultural land. The weather analysis shows that the climate at Wangaratta has infrequent, yet distinct, instances of extreme fire weather conditions assumed by AS3959. The fire history confirms that there have been fires in the past that caused impact to the community. The grassy agricultural land with isolated clumps of trees in the landscape outwards from both sites, in the direction away from Page 42 of 55

43 Wangaratta, indicates that if a fire were to impact the sites it would be a grassfire, rather than a more intense forest fire.. Maintaining any grass close to assets in the growth areas in a short condition would greatly reduce the fire intensity and level of impact. The topography within the study sites and 2km beyond is generally flat. There are some steeper slopes beyond 2km of the sites (e.g. within the Warby Ranges), which could contribute to locally extreme fire behaviour, however any such behaviour is unlikely to directly influence the impact to either site due to physical separation. As forest is not in close proximity to either site, and grassy fuels generate only limited and short distance spotting, ember attack is not likely to be a significant mechanism of bushfire attack at either site. Some long-range ember travel from the forest or woodland may be observed in extreme conditions, but the ember density would not be severe. BAL-12.5 construction would provide adequate protection to new buildings against the level of ember attack likely at either site. Radiant heat and direct flame contact from a grass fire are the main mechanisms of fire impact that are likely at both sites. However subdivision layout that provides appropriate setbacks from the unmanaged grassland, typically by perimeter roads, low threat public open space and/or setbacks of dwellings on private land. Assuming that the subdivision layout incorporates appropriate bushfire design principles, houses respond to the BPA (i.e. are built to a minimum of BAL-12.5) and there is some perimeter vegetation management to provide a buffer from hazard, the housing development would adequately respond to the landscape risk scenario type A. From a planning point of view this means that the level of bushfire risk would be acceptable. The large established low-threat suburban area of Wangaratta, to which these growth areas are attached, offers multiple locations in which people could seek refuge from any bushfire threat on or near the town perimeter. The range of suppression resources afforded by the greater Wangaratta area is also considerable with two brigades close by. These considerations further reduce the risk to life and property, as they will facilitate suppression, asset protection and effective shelter. A fundamental principle of bushfire risk mitigation is to direct development away from high-risk areas as this reduces the exposure of people to potential impact. The moderate level of bushfire risk to the proposed development is in accordance with this principle. Wangaratta can provide a large low risk area in which people from higher risk areas can seek shelter from bushfire. This function of Wangaratta should be emphasised to the broader community. Terramatrix consider the proposals of residential growth to both the west and south of Wangaratta to be appropriate from a bushfire risk perspective. Some risk of impact from grassfire Page 43 of 55

44 exists at these sites, however it can be adequately mitigated in the planning and implementation of the development. 6 Planning and design response This section of the report provides guidance about appropriate bushfire risk mitigation measures for the greenfield residential expansion to the west and south of Wangaratta. There are actions within the Strategy around the implementation of the greenfield residential development. Some of these actions directly relate to the advice provided in this planning and design response. Action numbers from Section (Refer Pp 92-98) of the Strategy are given where relevant. Endorsements and recommendations by Terramatrix are underlined. 6.1 Growth area layout The impact of bushfire on settlements and towns is greatest at the urban interface where people and property are closest to the areas with the most hazardous vegetation (I.e. available bushfire fuel). Maintaining a low-threat buffer between housing and hazardous vegetation is a key principle for reducing the impact at the interface as it physically separates people and assets from extreme fire behaviour. A secondary principle is, therefore, to reduce the length of interface around a settlement. The logic here is that by reducing the interface length, the fewer assets are exposed to the bushfire hazard and the less area requires maintenance therefore increasing the likelihood it will be well maintained throughout the fire season. On this basis Terramatrix support the avoidance of leap-frog development, as advocated in the Strategy (Section , p. 92), as it aligns with the principle of minimising the length of interface. The Strategy also recommends the preparation of structure planning, rezoning, use of Development Plan Overlays (DPO) and precinct wide planning (p. 92), which is reflected in Actions 1-3 and 9. Terramatrix strongly support the Actions of 1-3 and 9 in Section of the Strategy as these planning stages offer a major opportunity for clarifying when and where bushfire mitigation measures should be used in the development and for integrating them with other design elements. This clarity will also assist Council, householders and developers to understand their on-going contribution to the long-term management of risk mitigation measures. The Strategy identifies the eastern portion of the western growth area (215 ha east of Reith Road) for short to medium term residential growth, while the western portion (520 ha west of Reith Road) is identified for long-term residential growth. Terramatrix support this two-tier staging either side of the boundary formed by Reith Road. As the land in the western portion has been identified for use only if required, Terramatrix recommend that the planning process, recommended to commence immediately in the Strategy, consider an arrangement of housing, other land uses and associated access within the eastern portion that would be appropriate from a bushfire safety perspective if development of the western portion were not to Page 44 of 55

45 proceed. In other words, the development to the east of Reith Road should have bushfire risk mitigation measures contained within it, and not be reliant on any bushfire risk mitigation measures that may be planned for the long-term area. Planners and designers should therefore consider two eventualities for the Reith Road corridor. One is that it forms the outer consolidated edge of Wangaratta, acting as the boundary between low-threat residential development and farmland, providing longitudinal access and acting as a fuel buffer. The other eventuality is that the Reith Road corridor operates as a major north-south arterial road within a larger western suburban area providing access but not having any major function as a low fuel area. The width of the road corridor, the design and management of adjacent linear open space, intersections with other roads and adjacent land uses will be important considerations to ensure the long-term flexibility of this corridor. 6.2 Construction standard Both sites currently lie within a Bushfire Prone Area and therefore any development needs to respond to this designation. The developed areas of Wangaratta, away from bush and grassland are not in the BPA (Refer Map 10). The usual method of complying with such a designation is to build to a construction standard as per the Australian Standard for Building and Construction in Bushfire Prone Areas AS-3959:2009 (Standards Australian, 2009). The minimum construction standard in a BPA is BAL Council should, however, consider that the urban-hazard interface will shift outwards as the greenfield development sites become developed. Housing lots currently at the edge of town will become contained within the low-risk urban area as more subdivision and housing construction occurs around it and outwards from it. Assuming that the developed lots have limited vegetation and are excludable from classification, as per AS3959, much of the development sites currently with the BPA would no longer meet the BPA mapping criteria. Only the urban interface would legitimately meet the BPA criteria. Implementing a full suite of bushfire risk mitigation measures for every house built in the growth areas may be viewed as undesirable as implementing these measures imposes a cost, and, due to the enclosure by urban areas, the bushfire risk may be short-lived. The grassfire hazard would, however, need to be managed as the development occurred. It is the view of Terramatrix that there are two options available for responding to the BPA. The first is to accept the current extent of the BPA mapping, the other option is to work with DTPLI to have areas of the BPA excised in stages commensurate with the development stages and reflecting the diminishing fire risk of the inner areas as a result of development. It is recommended that Council discuss these options with the CFA, potential developers and DTPLI. It is recommended that Page 45 of 55

46 Council choose one (or a combination) of the two options explained below for combatting potential radiant heat and flame contact. A combination of rolling buffer as development proceeds, with the final row of houses being built to BAL-12.5 may be a good option Option 1 Conforming with the current BPA extent A standard BAL assessment at either Wangaratta growth area would return a BAL 12.5 assuming a setback of 19m from unmanaged grassland. Therefore, if the housing is built to a construction standard of BAL-12.5 and a buffer at least 19m wide is maintained as short grass on the outer edge of all developments the BPA requirements would be met. The position of the buffer would have to move outwards (a rolling Asset Protection Zone (APZ)) as the development progressed, to constantly offer adequate safety for each new house. Once houses are enveloped within suburbia they would carry a BAL that arguably exceeds the level of risk. BAL 12.5 construction carries additional construction cost above average BAL-free construction costs. In proceeding with this option Council should consult with potential developers and assess whether the extra cost that would be borne by consumers would diminish the viability of the development, particularly since the risk is likely to be temporary. Maintenance of the buffer at least 19m wide also carries cost and responsibility. If development should halt, for example due to an economic down turn, Council and the developer should think through the implications of having the buffer in that position for an undefined period of time. Council should also seek clarification from any developer that adequate buffer maintenance arrangements are in place, for each possible buffer position. The 19m buffer could be partially, at least, accommodated within road reserves at the outer edge of development stages. This would mean that if development were to proceed to fully occupy each development stage, and roads bound these, the developer is unlikely to lose any developable area to the buffer Option 2 Excise from BPA This option would mean that a large proportion of the housing in the development would not have to be built to a BAL. Terramatris understands that there are precedents for this approach to dealing with the BPA in growth areas around metropolitan Melbourne. In this scenario it was agreed that if a 60m buffer was maintained at the edge of any development it was deemed to be within a low-threat area and therefore not requiring a response to the BPA. The added cost of BAL-12.5 construction would no longer be a factor requiring consideration, however managing the maintenance of the 60m buffer would be an additional imposition,. The net developable area may also be affected as extra land adjacent to road reserves would be temporarily, at least, excluded from development and maintained in a low- Page 46 of 55

47 threat state for as long as the edge of the agricultural land is adjacent. 6.3 Development pattern Independent of which BAL and buffer combination Council and relevant authorities decide upon, defining development stages is advised. These stages could be aligned to existing cadastre or be identified as blocks within any growth area structure plan that may reconfigure the cadastre. The use of perimeter roads to define development stages is strongly recommended. A hypothetical example of development stages and associated buffers was explored in Map 17. During a site visit it was noted that some of the current development occurring to the west of Christensen s Lane and Worland Road (such as the Bella Vista development) was occurring in rectangular stages. It was noted that the dwellings at the western end of the development were constructed prior to the dwelling on the eastern blocks. This west to east order of construction is sensible from a bushfire risk perspective as the western boundary and buffer can be established first then housing on the inner side proceeds with the protection already in place. Council and the developer should consider implementing development within stages in a west to east construction order. Page 47 of 55

48 Rural City of Wangaratta Strategic Bushfire Risk Assessment for the Wangaratta Residential Growth Areas Map 17. Hypothetical example of development stages in the western growth area with the Option 1 and Option 2 buffers indicated Page 48 of 55

49 6.4 Defendable space planning Access roads provide an opportunity for ensuring permanent low-fuel areas. A standard suburban street usually has a total road reserve width of between 17 and 21m. Depending on the class of road the actual carriageway width may be up to 10m wide. Feeder and arterial roads may be wider. Gravel shoulders on semi-rural roads can also be considered to be lowfuel where adequate grading occurs to prevent weed growth. Footpaths (1.2+m) and shared paths (2.5+m) can also offer a permanent low fuel strip. Mown grass and garden beds (where they meet CFA BMO inner zone standards) are frequently used as another way of achieving low threat areas. While this is a commonly used measure it requires ongoing maintenance. It would pay to try to integrate mown grassy areas and gardens for defendable space purposes into the overall open space strategy of the development. Where defendable space is planned to be provided on private land, Council should ensure that adequate planning controls exist to prevent dwelling construction closer to the hazard than planned. For example this could be achieved by specifying a setback within a Development Plan Overlay. Fire management controls could also be supported by fire management planning, for example the MFMP could specify that house blocks on the urban interface be maintained to an appropriate vegetation management standard. Strategic placement of other managed open spaces provides a further opportunity for settlement buffering. Sporting grounds, golf courses and parks should be located on the outer edges of the growth areas. Actions 11 and 16 of Section of the Strategy should be implemented with mindfulness of the opportunities of combining open space and recreational uses with the provision of defendable space. Council are recommended to plan a layout of defendable space that is integrated with the road and path network and other managed open space. Valuable native vegetation that cannot meet the defendable space standards should be provided with the relevant AS3959 setbacks. Further guidance about the layout and vegetation management for defendable space can be found in Practice Note 65 (Particularly Appendix 2) (DTPLI, 2011) and Planning for Bushfire, Victoria (CFA, 2012). 6.5 Access planning The use of perimeter roads is a recognised bushfire mitigation strategy within subdivisions. The benefits of perimeter roads are two-fold. Firstly they provide a structured, permanent lowfuel strip at the edge of the development, and secondly they facilitate access and egress for suppression and evacuation. Subdivision planners should attempt to contain each development stage within perimeter roads. All outer perimeter roads should be through-roads providing at least two directions of access and egress for the occupants of any dwelling along it. Thus the housing at the edge of each development stage would Page 49 of 55

50 ideally have an outward facing street frontage rather than be inward facing with rear fences to the hazard. A street layout with numerous cul-de-sacs should be avoided. Long cul-de-sacs servicing many dwellings and cul-de-sacs opening to the western face of the development should be especially avoided. Planning for Bushfire Victoria: Guidelines for Meeting Victoria s Bushfire Planning Requirements (CFA, 2012) provides guidance on these matters. Perpendicular roads, into the urban area, that intersect with the perimeter road should also be provided. It is undesirable for a person living on a perimeter road to have to travel a long distance parallel to the bushfire hazard before entering the relative safety of the inner suburban area. In the eastern portion of the western growth area this means that Council should consider additional through roads between Reith Road and Christensen Lane or Worland Road above the existing access provided by Wangandary Road and Lindner Road. If the western portion of the western growth area proceeds additional roads creating links between Warby Range Road and Reith Road should be considered. In the design of the southern growth area it would be worth considering an extension of Salisbury Street to meet Clarkes Lane. Terramatrix strongly support the proposal to create a link across Three Mile Creek in the vicinity of Cruse Street as this would create valuable access and egress opportunities. Some road reserves contain native vegetation. This is acknowledged in Action 25 of Section of the Strategy, which advocates acknowledging the fire risk posed by roadside vegetation. For example, Wangandary Road has remnant eucalypt woodland vegetation on either side of it. Under the right weather conditions and assuming an ignition in a relevant position, fire could spread along such strips of vegetation. Under severe fire weather conditions the safety of road users adjacent to the fire may be jeopardised. It is assumed that the greenfield development will increase the volume of traffic on most, if not all the existing roads associated with the growth areas. Upgrades to the roads to allow for a greater traffic volume and travel speed are also foreseen. Some vegetation removal or modification may be required to achieve such upgrades. The general function of the major growth area roads will change as a result of the development therefore, Terramatrix recommend that the function of the roads as Fuel Reduced Corridors or Priority Access Roads for listing within the MFMP should be reviewed in light of the changing land use. Where a road and road reserve is planned to provide defendable space within the future development, the vegetation within the defendable space area should be managed as per Appendix 2 of Practice Note 65 (DTPLI, 2011). If this cannot be achieved alterative defendable space will need to be provided. Page 50 of 55

51 Bushfire design standards for access routes within the BMO are given in Planning for Bushfire, Victoria. Guidelines for Meeting Victoria s Bushfire Planning Requirements (CFA, 2012). This could be used as a guide. 6.6 Vulnerable uses The Strategy indicates that it is likely that the growth areas will contain uses other than just general residential use, with some commercial and community areas to be considered. Action 15 in Section suggests that an assessment for the need for these services be conducted. Clause of the Wangaratta Planning Scheme sets out the standards for construction in the BMO of other occupied buildings (i.e. accommodation (other than a dwelling or a dependent persons unit), child care centre, education centre, hospital, leisure and recreation, and place of assembly). A major difference in the requirements for these other occupied buildings compared with dwellings is that they require additional defendable space (calculated to reduce radiant heat to below 10 kw/m 2 ). The reason for this is that there may be many occupants of these buildings, including children, the elderly or infirm. Additional defendable space provides a slightly more cautious approach for protecting human life. While the growth areas are outside of the BMO (meaning Clause does not apply) the premise of providing extra safety for these types of uses is valid and could be accommodated at the subdivision planning stage. On this basis, Terramatrix recommend that, if the needs analysis indicates that they are required, housing for the elderly, nursing homes, health facilities, schools, child care centres, etc. be planned for placement in the inner areas of the development rather than on the outer edges. 6.7 Housing density Bushfire impact to settlements is greatest at the interface. Therefore locating higher density housing away from the interface is an appropriate strategy for reducing the exposure of life and property. Actions 8 and 32 in Section of the Strategy encourages subdivision planners and designers to locate medium density housing close to commercial and community areas. Terramatrix supports Actions 8 and 32 so long as medium density housing is not located on the development interface. This relates to the discussion in Section 6.6. With regards to the location of medium density housing near in any commercial and community facilities in the area currently zoned B4Z, it would be desirable to cluster the medium density housing to the east and south-east of the B4Z but not immediately adjacent to Greta Road. Lower density dwellings generally suffer higher bushfire impacts than higher density housing (Syphard et al., 2012) due to lower density housing generally being closer and more surrounded by hazardous vegetation. It is therefore important to consider the housing density and vegetation conditions that will occur at the interface of the development once completed. Page 51 of 55

52 The observations of fuel conditions in the existing areas RLZ and LDRZ at Wangaratta indicate that there is generally less opportunity for wildfire to penetrate the LDRZ than RLZ. Action 24 of Section , pertaining to the western area, recommends that the density of development becomes sparser in the parts of the western growth area closest to the Warby Ranges. On this basis, Terramatrix support some reduction in development density towards the Warby Ranges within the growth area, pending that the density of housing and/or continuity of fuels at the interface will not facilitate fire penetration more than the existing examples of LDRZ near the growth areas. Consideration should be given to mechanisms for ensuring vegetation management on any allotments, particularly LDRZ areas, at the interface. reticulated water to any of these allotments would be desirable as it negates any consideration of a static water supply. If reticulated water is not provided a static water supply for fire fighting purposes should be considered. The current water requirements, as specified by the CFA, for developments with the BMO could be used as guide for any such consideration (Refer Figure 8). 6.8 Emergency services Action 22 of recommends consideration of additional emergency services for the western growth area. Council should consult with CFA in regard to any need to provide for the provision of fire services for an expanded Wangaratta, particularly for the substantial increase of people and assets in the western growth area 6.9 Water resources Figure 8. Minimum static water requirements for BMO developments (CFA, 2012) The standard provision of reticulated water and hydrants for a residential zone one subdivision would provide adequate water resources for suppression purposes. It is noted that some LDRZ may be incorporated within the development. Providing Page 52 of 55