Bushfire Attack Level (BAL) Report Smythes Rd, Delacombe

Transcription

1 Bushfire Attack Level (BAL) Report Smythes Rd, Delacombe 13 December 2015

2 Contents Summary of Conclusions...4 Introduction...5 Objective of the Report...5 General Terms of Engagement for Bushfire Property Assessment...5 Regional, Site and Proposal Description...6 Regional Description...6 Site Description...6 Proposal Description...7 Bushfire Assessment Parameters...8 Vegetation Classification...9 Distance to Classified Vegetation...9 Assessment of Slope...9 Potential Bushfire Scenario Potential Impact: Bushfire Attack Level (BAL) Determination Conclusions References Appendix 1 Photos of Site Appendix 2 Supporting Standards Appendix 3 Recommended Property Management Conditions

3 Summary of Conclusions The proposed development site is located at Smythes Road, Delacombe and is within a bushfire prone area. The proposal is for the subdivision and residential development of the subject site, creating approximately 157 lots. The report determines a Bushfire Attack Level (BAL) rating for the site according to the performance requirements of the Building Code of Australia (Standards Australia, 2009). The bushfire assessment was conducted on the 1 st of December, The bushfire assessment process demonstrates that the entire development site can be rated the Bushfire Attack Level (BAL) rating of BAL Future development on all lots on the site must comply with the specifications for BAL 12.5 as detailed in AS

4 Introduction Objective of the Report Provide a Bushfire Attack Level (BAL) rating for the client according to the performance requirements of the Building Code of Australia (BCA). General Terms of Engagement for Bushfire Property Assessment The general terms of engagement and conditions set out below apply to all work undertaken by Ecotide Pty Ltd in the general field of bushfire property assessments. Role of Ecotide Pty Ltd ECOTIDE PTY LTD will: Act in all professional matters as a faithful advisor to its clients. Exercise all reasonable skill and care in the provision of its professional services and shall abide by the codes of ethics or practice specified by the Environment Institute of Australian and New Zealand and other relevant professional bodies. Provide its services to clients effectively within the limitations imposed by the scope of work and budgets allocated by its clients. Role of the Client A client shall make available to ECOTIDE PTY LTD, as soon as practical after a commission has been awarded, all information, documents, maps and other particulars relevant to the subject commission. A client shall cooperate with ECOTIDE PTY LTD in all reasonable ways regarding in the conduct of a commission being undertaken on its behalf. Bushfire Property Assessment Reports ECOTIDE PTY LTD shall retain ownership of the reports, drawings, designs, displays and other work produced by ECOTIDE PTY LTD during the course of fulfilling a commission until final payment by the client. When the client pays for the services the client has read and FULLY understands: That managing the bushfire risk is a complex set of interrelated activities and environmental parameters and that the risk cannot be fully mitigated to their personal safety, family and assets. That even a well-planned, carefully constructed home with management of the surrounding vegetation can be vulnerable to bushfire. That survival in a bushfire is critically dependent on a combination of preparedness (competency) and activation of effective survival strategies and plans (capacity) of residents. That dwelling occupants should always develop a written bushfire survival plan. That the concepts and the contents of the report become their responsibility to implement. That the company (Ecotide Pty Ltd) is exempt from any liability now and into the future for any loss whatsoever resulting from the impacts of bushfires. 5

5 Regional, Site and Proposal Description Regional Description The site is located in Delacombe, a south-western suburb of the city of Ballarat, within the City of Ballarat Municipality. The region is characterised by developed and developing urban residences with associated infrastructure and managed parks. The fire threat that interfaces with the south-west of Ballarat is primarily from grassland, typically associated with pastoral land. Generally, as the residential development expands from Ballarat this grass fire threat is reduced. Figure 1. Regional view of the Ballarat (Google Inc., 2013). Site Description The development site, Smythes Road, Delacombe, occurs on the south-west boundary of Ballarat, adjacent to currently developing land. The site extends south from Smythes Road/Glenelg Highway, and is bounded by developing land to the east and rural properties with pastoral land to the south and west. The terrain over the site and surrounding area is flat, with a small creek/drainage line occurring over the northeast. The current condition of the site is predominantly pastoral grassland. The zoning of the lots associated with the development site are Urban Growth Zone (2), and the Bushfire Management Overlay (BMO) does not apply to the site. The site is within a designated Bushfire Prone Area (BPA). 6

6 Bushfire Assessment Parameters The level of bushfire attack estimation is derived from the parameters measured at the time of the site inspection. These bushfire parameters are detailed in the following sections, and are used to determine the subsequent Bushfire Attack Level (BAL) in accordance with AS3959 (2009). Figure m assessment radius around the development site (Google Inc., 2013). 8

7 Vegetation Classification Table 1. Classification of vegetation within the assessment area. Location North East South West Classification Low threat Low threat Grassland Grassland Description f. low threat vegetation cultivated gardens and mown grass f. low threat vegetation cultivated gardens and mown grass Pastureland with grass and isolated trees. Pastureland with grass and isolated trees. Distance to Classified Vegetation Distance from the development to the edge of the classified vegetation. Table 2. Distance of the classified vegetation from the site. North East South West Line of Sight Measured from n/a n/a n/a n/a Distance n/a n/a n/a n/a Assessment of Slope The estimate of the average slope under the classified vegetation is shown in the table below. Table 3. Average slope measured under the classified vegetation. North East South West Slope Flat Flat Flat Flat 9

8 Figure 4. Summary of bushfire parameters (Google Inc., 2013). 10

9 Potential Bushfire Scenario The predominant bushfire activity for Victoria involves north, north-westerly winds, followed by a south-westerly wind change. Previous bushfire activity, such as the Black Saturday and Ash Wednesday fires, provide clear illustrations of these scenarios on high bushfire threat days. A northerly scenario may cause a fire ignited in grassland to the west of Ballarat to advance rapidly down to the south, potentially jumping the Glenelg Highway. Existing and developing residents and infrastructure in these regions may slow the rate of fire spread, however, grassland fires generally move at a relatively high speed in high risk weather conditions. If a fire in this scenario were allowed to burn uncontrolled across the Glenelg Highway, then there is the potential for a south-westerly wind change to direct the flank of the fire in a new front towards the proposed development site. Grass in the area to the west and south of the site shows signs of at least partial management as a result of grazing, and the expected grass fire intensity would therefore likely be reduced when compared to a standard grass fire. In addition, development is continuing in this area, and is expected to expand to the west of the site in the future. Such development would significantly reduce the potential grass fire risk to the site. Potential Impact: Ember Attack: Radiant Heat: Localised Flame Contact Flame Contact From Fire Front Extreme Fire Behaviour 11

10 Bushfire Attack Level (BAL) Determination The appropriate Bushfire Attack Level (BAL) is determined in accordance with the methodology in AS3959, which accounts for the previously detailed bushfire assessment parameters. The determination is based on FDI 100, as is standard for Victoria. Table 4. Bushfire Attack Level (BAL) determination North East South West Classification Low threat Low threat Grassland Grassland Distance n/a n/a n/a n/a Slope Flat Flat Flat Flat BAL BAL 12.5 applies as the minimum standard for the construction of new buildings within Bushfire Prone Areas, in accordance with the changes to Bushfire Prone Areas set out by the Minister for Planning on May 28 th,

11 Conclusions This site is assessed as BAL 12.5, the minimum standard for new buildings within a Bushfire Prone Area. Future development of the lots should be designed and constructed in accordance with BAL 12.5 specifications as detailed in AS3959:

12 References CFA. (2011). Landscaping for Bushfire. Victoria. Google Inc. (2013). Google Earth Pro Standards Australia. (2009). AS Construction of buildings in bushfire-prone areas. 14

13 Appendix 1 Photos of Site 15

14 Appendix 2 Supporting Standards 16

15 Appendix 3 Recommended Property Management Conditions It is recommended that the property should be managed in a similar condition to defendable space under the Bushfire Management Overlay (BMO). These conditions are: Within 10 metres of a building flammable objects such as plants, mulches and fences must not be located close to the vulnerable parts of the building such as windows, decks and eaves. Trees must not overhang the roofline of the building; touch walls or other elements of a building. Grass must be no more than 5 centimetres in height. All leaves and vegetation debris must be removed at regular intervals. Shrubs should not be planted under trees. Plants greater than 10 centimetres in height at maturity must not be placed in front of a window or other glass feature. Tree canopy separation of 2 metres and overall canopy cover of no more than 15% at maturity. It is recommended that the property owner refer to the CFA document, Landscaping for Bushfires. 17