BUSHFIRE PROTECTION ASSESSMENT

Transcription

1 BUSHFIRE PROTECTION ASSESSMENT Proposed Dormitory The Scots College, 453 Culburra Road, Wollumboola Prepared for Presbyterian Church (NSW) Property Trust 27 June 2013

2 DOCUMENT TRACKING ITEM Project Name Project Number Project Manager Reviewed by DETAIL Bushfire Protection Assessment, Proposed Dormitory The Scots College, 453 Culburra Road, Wollumboola 12SGBBUS-0125 Julie Holden David Peterson Approved by David Peterson Status FINAL Version Number V2 Last saved on 27 June 2013 ACKNOWLEDGEMENTS This document has been prepared by Eco Logical Australia Pty Ltd. Disclaimer This document may only be used for the purpose for which it was commissioned and in accordance with the contract between Eco Logical Australia Pty Ltd and Presbyterian Church (NSW) Property Trust. The scope of services was defined in consultation with Presbyterian Church (NSW) Property Trust, by time and budgetary constraints imposed by the client, and the availability of reports and other data on the subject area. Changes to available information, legislation and schedules are made on an ongoing basis and readers should obtain up to date information. Eco Logical Australia Pty Ltd accepts no liability or responsibility whatsoever for or in respect of any use of or reliance upon this report and its supporting material by any third party. Information provided is not intended to be a substitute for site specific assessment or legal advice in relation to any matter. Unauthorised use of this report in any form is prohibited. E C O L O G I C A L A U S T R A L I A P T Y L T D i

3 Contents List of Figures... iii List of Tables... iii 1 Property and proposal Description of proposal Location and description of subject land Bushfire threat assessment Vegetation types and slope Asset Protection Zones (APZ) APZ maintenance plan Construction standard Water supply Gas and electrical supplies Access Assessment of environmental issues Summary of protection provisions and conformity with PBP Conclusion References Photographs Appendix A E C O L O G I C A L A U S T R A L I A P T Y L T D ii

4 List of Figures Figure 1: Location... 2 Figure 2: Bushfire hazard assessment... 3 Figure 3: Development proposal... 4 List of Tables Table 1: Threat assessment, APZ and category of bushfire attack... 6 Table 2: Assessment of conformity with PBP... 9 E C O L O G I C A L A U S T R A L I A P T Y L T D iii

5 1 Property and proposal Name: Postal address: Presbyterian Church (NSW) Property Trust C/- Allen Price & Associates PO Box 73, Nowra NSW 2541 Street or property Name: 453 Culburra Road Suburb, town or locality: Wollumboola Postcode: 2540 Lot/DP no: Lot 2 DP Local Government Area: Type of development: Shoalhaven City Council School dormitory (SFPP facility) 1.1 Description of proposal Presbyterian Church (NSW) Property Trust commissioned Eco Logical Australia Pty Ltd (ELA) to prepare a bushfire protection assessment (BPA) for a proposed school dormitory at The Scots College, 453 Culburra Road, Wollumboola (hereafter referred to as the subject land). As the development is a school dormitory, it is assessed as a Special Fire Protection Purpose Development. This assessment has been prepared by the ELA Senior Bushfire Consultant, Julie Holden (FPAA BPAD-A Certified Practitioner No. BPAD-PA-23572) with quality assurance review by David Peterson. Both Julie and David are recognised by the NSW Rural Fire Service as qualified bushfire consultants in bushfire risk assessment. The subject land was inspected on 26 April Location and description of subject land The subject land is located on the northern side of Culburra Road in the south coast locality of Culburra as shown in Figure 1. Figure 2 shows the subject land and the location of the proposed dormitory in relation to the nearest bush fire prone vegetation which is Blackbutt Forest to the east, and Casuarina Forest fringed with mangroves and saltmarsh to the north on the Crookhaven River. E C O L O G I C A L A U S T R A L I A P T Y L T D 1

6 Figure 1: Location E C O L O G I C A L A U S T R A L I A P T Y L T D 2

7 Figure 2: Bushfire hazard assessment E C O L O G I C A L A U S T R A L I A P T Y L T D 3

8 Lot 2 DP Figure 3: Development proposal E C O L O G I C A L A U S T R A L I A P T Y L T D 4

9 2 Bushfire threat assessment The subject land is identified as Bush Fire Prone Land by Shoalhaven City Council. The following assessment is prepared in accordance with Section 100B of the Rural Fires Act 1997 and Planning for Bush Fire Protection (RFS 2006), herein referred to as PBP. The use of the building is defined as Special Fire Protection Purpose (SFPP) as it is a school and accordingly a Bush Fire Safety Authority from the NSW Rural Fire Service is required for the development. The Authority is sought based on the details of this Bushfire Protection Assessment prepared in accordance with Section 100B of the Rural Fires Act 1997, Clause 44 of the Rural Fires Regulation 2008, and the Planning for Bushfire Protection Guidelines 2006 document (NSWRFS 2006). 2.1 Vegetation types and slope In accord with PBP the predominant vegetation class has been calculated for a distance of at least 140 m out from the proposed dormitory and the slope class most significantly affecting fire behaviour has been determined for a distance of at least 100 m in all directions. The predominant vegetation and effective slope assessments are shown in Table 1 (p. 6). The site is characterised by a flat, cleared area where the development is proposed, bordered to the north and north-west by a steep embankment which drops down to a strip of remnant vegetation along the Crookhaven River. The riparian vegetation to the north is mangroves fringed with a 5-15 m wide strip of Casuarina Forest below the embankment on 0-5 degree downslopes. This vegetation is classified as rainforest by PBP in recognition of the reduced fire behaviour in the lineal strip. The riparian vegetation to the north-west is mangroves fringed with a 30 m wide strip of Casuarina Forest below the embankment on a 2 degree downslope. This vegetation is classified as forested wetland by PBP. On top of the embankment to the east is Blackbutt Forest on 0-5 degree downslopes, classified as forest by PBP. To the west, the canopy trees of this Blackbutt Forest vegetation community remains, with a managed understorey, classified as forest by PBP. Managed grazing lands are in all other directions. E C O L O G I C A L A U S T R A L I A P T Y L T D 5

10 3 Asset Protection Zones (APZ) Table A2.6 of PBP has been used to determine the width of Asset Protection Zones (APZ) for the proposed development using the vegetation and slope data identified above and replicated in Table 1. The proposed APZ are also shown in Table 1. The Acceptable Solution APZ cannot be achieved to the north-west. The vegetation in this direction is on a very slight downslope and is only 30 m wide therefore the NBC Bushfire Attack Assessor v2.1 was used to conduct an alternate solution by calculating the required APZ to achieve no more than 10kW/m 2 of radiant heat at the building face based on these above specific parameters. This was achieved by using the actual slope of 2 degrees (rather than the PBP slope class of 0-5 degrees which produces an APZ based on 5 degrees) and the maximum fire width that could be achieved through the corridor, being no more than 30 m. The model input parameters of slope and flame width (fire front) was adjusted in the model to calculate the alternate solution and achieve the minimum APZ. Table 1 below outlines the APZ calculations and the model report is attached in Appendix A. Table 1: Threat assessment, APZ and category of bushfire attack Direction from dormitory Slope 1 Vegetation 2 PBP required APZ 3 10kW/m2 Modelled APZ 4 Proposed APZ AS3959 Construction Standard 5 Comment North downslope Rainforest (Remnant) 40 m m BAL 12.5 APZ with subject land. Riparian strip of vegetation meters wide, so rainforest setback applied. East downslope Forest 70 m m BAL 12.5 APZ with subject land West downslope Forest 70 m m BAL 12.5 APZ extends over adjoining lot to the west. This lot is within the same ownership and the APZ will be formalised in accordance with PBP requirements. Northwest 2 0 downslope Forested wetland n/a 36m --- BAL 12.5 APZ with subject land South Upslopes and flat land Managed land BAL 12.5 APZ within managed landscaping around building including access road and car parking. 1 Slope most significantly influencing the fire behaviour of the site having regard to vegetation found. Slope classes are according to PBP. 2 Predominant vegetation is identified, according to PBP and Where a mix of vegetation types exist the type providing the greater hazard is said to be predominate. 3 Assessment according to PBP. 4 Modelled using NBC Bushfire Attack Assessor v Assessment according to AS E C O L O G I C A L A U S T R A L I A P T Y L T D 6

11 4 APZ maintenance plan The proposed APZ is in place and no further vegetation clearance or tree removal is required to support the proposed development. Ongoing maintenance of the APZ is required and fuel management within the APZ is to be as follows: No tree or tree canopy is to occur within 2 m of the development roofline; The presence of a few shrubs or trees in the APZ is acceptable provided that they: o o o Are well spread out and do not form a continuous canopy; Are not species that retain dead material or deposit excessive quantities of ground fuel in a short period or in a danger period; and Are located far enough away from the building so that they will not ignite the building by direct flame contact or radiant heat emission. Any landscaping or plantings should preferably be local endemic mesic species or other low flammability species; A minimal ground fuel is to be maintained to include less than 4 tonnes per hectare of fine fuel (fine fuel means ANY dead or living vegetation of <6 mm in diameter e.g. twigs less than a pencil in thickness. 4 t/ha is equivalent to a 1 cm thick layer of leaf litter); and Any structures storing combustible materials such as firewood (e.g. sheds) must be sealed to prevent entry of burning debris. The western APZ is partly over a neighbouring lot under the same ownership. formalised in an easement. This APZ should be 5 Construction standard In response to the predicted bushfire attack the proposed dormitory is to be constructed to a BAL-12.5 standard under Australian Standard AS Construction of buildings in bushfire-prone areas (Standards Australia 2009). Furthermore, the provisions of Section 3 Construction General of AS and the ember protection provisions outlined on Page 10 of the 2010 Appendix 3 Addendum to PBP are also required for the proposed dormitory where applicable. E C O L O G I C A L A U S T R A L I A P T Y L T D 7

12 6 Water supply The subject land will be serviced by reticulated water network, which will be expanded to support the proposed development. The furthest point from any future development to a hydrant will be less than 70 m. The reticulated water supply will comply with the acceptable solutions within Section of PBP. 7 Gas and electrical supplies In accordance with PBP, electricity should be underground wherever practicable. Where overhead electrical transmission lines are installed: Lines are to be installed with short pole spacing, unless crossing gullies, and No part of a tree should be closer to a powerline than the distance specified in Vegetation Safety Clearances issued by Ausgrid (NS179, December 2010). Any gas services are to be installed and maintained in accordance with AS/NZS 1596:2008 (Standards Australia 2008). 8 Access A single property access road / driveway linked to an access and parking configuration to accommodate buses provides access to the proposed dormitory. The PBP performance criteria for SFPP internal roads is that internal road widths and design enables safe access for emergency services and allow crews to work with equipment about the vehicle and the intent of measures is to provide safe operational access for emergency services personnel in suppressing a bush fire while residents are accessing or egressing an area. The property access road is 4 m wide for the first 50 m before it links to the large bitumen carpark provided immediately south of the proposed dormitory. This section of road is short, on the non-hazard side of the development, links directly to the public road and has opportunities for vehicles to pull off the road provided by a large 58 space carpark directly accessible to the east and a hardstand area associated with existing site shed directly accessible to the west. There will be no parking along the access roads as on-site parking is provided for over 100 cars in dedicated car parks and the development is with an open space landscape (not forest or woodland). This enables the access to allow safe operational access with a 4m width in this section. The access road is not located near the bush fire hazard; it travels through managed land from the public Culburra Road, north through the subject land to the proposed dormitory building. In the event of bushfire any fire-fighters operating from a vehicle are unlikely to do so off the access road as this is more than 90 m from the closest bushfire hazard. A fire appliance can be located at either the existing dwelling or within the hardstand provided in the carpark immediately to the south of the proposed dormitory. At these locations crews can work with equipment around the vehicle in accordance with the performance criteria. E C O L O G I C A L A U S T R A L I A P T Y L T D 8

13 Being a school dormitory, the access configuration has been designed to accommodate large vehicles (i.e. multiple buses) and provides road sizes and design which will facility fire vehicle access. As detailed above the proposed access configuration can achieve the PBP SFPP access performance criteria and address the intent of measures. 9 Assessment of environmental issues At the time of assessment, there were no known significant environmental features, threatened species or Aboriginal relics identified under the Threatened Species Conservation Act 1995 or the National Parks Act 1974 that will affect or be affected by the bushfire protection proposals in this report. Shoalhaven City Council is the determining authority for this development; they will assess more thoroughly any potential environmental and heritage issues. 10 Summary of protection provisions and conformity with PBP Table 2 summarises the bushfire protection proposed for the dormitory and its conformity with PBP. Table 2: Assessment of conformity with PBP Bushfire Protection Provision Asset Protection Zones Proposal Table 1 (p. 6) identifies the size of proposed APZ. Alternate solution provided for NW APZ. See Section 3. Complies with PBP Yes, Construction Standards BAL-12.5 under AS ; see p.6 Yes Water supply Reticulated water is provided; see p. 7 Yes Access Alternate solution provided for access road width, see section 8. Yes 10.1 Conclusion In the author s professional opinion the bushfire protection requirements listed in this assessment provide an adequate standard of bushfire protection for the proposed dormitory, a standard that is consistent with Planning for Bush Fire Protection (RFS 2006) and should be issued a Bush Fire Safety Authority. Julie Holden Senior Bushfire Planner FPAA BPAD-A Certified Practitioner No. BPAD-PA E C O L O G I C A L A U S T R A L I A P T Y L T D 9

14 11 References Ausgrid Network Standard NS 179 Vegetation Safety Clearances (updated from Energy Australia Network Standard NS 179 (Vegetation Safety Clearances)). Ausgrid, Sydney. NSW Rural Fire Service (RFS) Planning for Bush Fire Protection: A Guide for Councils, Planners, Fire Authorities, Developers and Home Owners including the 2010 Appendix 3 Addendum. Australian Government Publishing Service, Canberra. Standards Australia Fire hydrant installations - System design, installation and commissioning, AS2419.1, Fourth edition 2005, SAI Global, Sydney. Standards Australia The storage and handling of LP Gas, AS/NZS 1596:2008, Fourth edition 2005, SAI Global, Sydney. Standards Australia Construction of buildings in bushfire-prone areas, AS SAI Global, Sydney E C O L O G I C A L A U S T R A L I A P T Y L T D 10

15 12 Photographs Photo 1: Looking south from below embankment up to dormitory site (to Photo 2) Photo 2: Looking north from dormitory site towards riparian vegetation (to Photo 1) Photo 3: Looking east across dormitory site Photo 4: Existing APZ to the west (looking south) E C O L O G I C A L A U S T R A L I A P T Y L T D 11

16 Appendix A E C O L O G I C A L A U S T R A L I A P T Y L T D 12

17 NBC Bushfire Attack Assessment Report V2.1 AS3959 (2009) Appendix B - Detailed Method 2 Print Date: 16/05/2013 Assessment Date: 16/05/2013 Site Street Address: Scotts College, Culburra Assessor: Local Government Area: Equations Used Mr Admin; admin Shoalhaven Transmissivity: Fuss and Hammins, 2002 Flame Length: RFS PBP, 2001 Rate of Fire Spread: Noble et al., 1980 Radiant Heat: Drysdale, 1985; Sullivan et al., 2003; Tan et al., 2005 Peak Elevation of Receiver: Tan et al., 2005 Peak Flame Angle: Tan et al., 2005 Alpine Area: No Run Description: Forested Weltand corridor Vegetation Information Vegetation Type: Forest Vegetation Group: Forest and Woodland Vegetation Slope: 2 Degrees Vegetation Slope Type: Downslope Surface Fuel Load(t/ha): 15 Overall Fuel Load(t/ha): 20 Site Information Site Slope: 0 Degrees Site Slope Type: Level Elevation of Receiver(m): Default Fire Inputs APZ/Separation(m): 36 Veg./Flame Width(m): 30 Flame Temp(K) 1200 Calculation Parameters Flame Emissivity: 95 Relative Humidity(%): 25 Heat of Combustion(kJ/kg) Ambient Temp(K): 308 Moisture Factor: 5 FDI: 100 Program Outputs Category of Attack: LOW Peak Elevation of Receiver(m): 7.34 Level of Construction: BAL 12.5 Fire Intensity(kW/m): Radiant Heat(kW/m2): 9.93 Flame Angle (degrees): 68 Flame Length(m): Maximum View Factor: 0.11 Rate Of Spread (km/h): 2.07 Inner Protection Area(m): 36 Transmissivity: Outer Protection Area(m): 0

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