Bushfire Protection - Article Example

BUSHFIRE PROTECTION Student’s name Course Professor Institution Date About the publication This article examines how the plan for bushfire has been designed to conform to the requirements of the Bushfire Management Overlay (BMO). It illustrates the measures and directions in designing permit applicants, the referral authorities as well as the responsible authority. This design outline follows CFA’s protocols as a referral authority under The Victoria’s planning system and the Planning and Environment Act 1987. The provisions for this planning and BMO are governed by the department of planning and Community Development (DPCD). Background information The bushfires that happened on the 7th of February 2009 made 173 people to lose their life, over 2000 homes were burnt and approximately 430,000 hectares of land damaged. This loss triggered the establishment of the 2009 Victorian Bushfires Royal Commission (VBRC) in response to the damages caused as a result of the bushfires in most parts .The main objective of the establishment of the VBRC was to conduct a study of the events that happened in the disaster and to set up recommendation to prevent such disasters from happening in future. The VBRC carried out an extensive research into the planning, sources of fire, response and the effects of the 2009 bushfires. It focused on gaining an understanding of what happened and how the dangers of such a disaster recurring may be minimized in the future. The need to prioritize the safety of the human life over other policy aims was one of the major findings of the VBRC .The Planning Scheme Amendment VC83 gave out new provisions for bushfire planning. The subsequent changes to the planning system are planned to reflect the new priority and the shared obligations of fire agencies, governments, Individuals, communities in reducing the possibility of a disaster similar to that of February 2009 from recurring. A number of recommendations were included in the final report for VBRC in relation to planning for bushfires to minimize such effects. Bushfire risk and house loss Bush behavior Having knowledge of the behavior bushfire and how it destroys houses is vital when designing and planning new development. The bushfire protection processes aim to minimize the effects of, radiant Heat, ember attack and direct flame contact. It is therefore vital to have vast knowledge of the behavior of bushfire in order to efficiently implement the protection measures of bushfires as outlined in the Clause 52.47 and 44.06 and of the planning scheme. There are three key factors that affect bushfire behavior. These are the topography, weather conditions such as wind and vegetation. Weather conditions are taken into account in the procedures that concerns the defendable space. Vegetation and topography are assessed in regard to the Bushfire Site Assessment. Topography The slope or topography of a place affects the intensity and the rate of spread of fire. As the slope increases the speed at which fire burns and intensity also increases. When a fire burns in an uphill, radiant heat, preheat the bush matter ahead of the fire by drying it and making it easier to burn. The general rule is that for every 10˚ of the slope, the fire doubles its speed and intensity. For instance, if a fire is travelling at 10km per hour on flat ground and it starts at 10˚ slope, it will double in Intensity and speed by burning up the hill at 20 km per hour. It’s known that fires Fires usually move slowly as the gradient decreases. The flames cover less fuel, and less radiant heat preheats the bush matter in front of the fire. For every 10˚ of a decreasing slope and the speed of fire is halved in this case. Images from the internet showing the behavior of bush fire uphill Weather Bushfires vary greatly and are unpredictable in regard to weather conditions. Weather conditions such as temperature, atmospheric conditions, wind, drought humidity as well as rainy conditions greatly determine the rate of bushfires. Windy and hot dry conditions can speed up the intensity and rate of spread of the bushfires. When the weather is hot, the vegetation dries out making it easier to burn and this can be worse depending on the dry conditions. During summer, there are several weather conditions that can necessitate flammability of the vegetation. It is known that dry vegetation will burn with ease. High temperatures and low humidity coupled with hot winds and dry vegetation can fuel up the burning process. A measure condition for weather is the Grassland Fire Danger Index (GFDI) and the Forest Fire Danger Index (FFDI). This measuring parameters are used to establish the fire danger rating. Wind Wind as weather condition greatly influences the intensity, direction and the speed at which fire will spread. The presence of pre-heating fuels and oxygen in the wind is the main reason behind the ease in spread since oxygen supports combustion. One of the most dangerous effects on behavior of the bushfire is the change in the direction of wind. This fact is true since most people who die in bushfires are usually caught off-guard as a result of change in the direction of the wind. A study in Victoria indicates that hot and dry winds originate from the north-west and north and are usually accompanied by winds coming from the south-west . How bushfire destroy houses Bushfire destroys houses through four main ways: radiant heat, ember attack, fire driven wind and direct flame contact. The most common way is through ember attack and this occurs when a burning twig is carried away by the wind from the vegetation to land on the building or areas around the building causing fire. The burning twigs can also ignite a fire on vegetation surrounding the fire hence causing fire. Radiant heat from the bush fire can burn houses by igniting surfaces without direct contact. This is possible drying out the vegetation next to the house, making them easier to burn or by simply melting plastic material around the house thus causing fire. Another mode is through direct flame contact where the fire front comes into contact with the building to cause fire. Fire-driven wind can lead to house fire by carrying embers and causing falling of burning trees to the building. An image showing the ember attacks on a building An image showing direct flame contact and radiant heat attacks on a building Protecting buildings and communities from bushfires There are several measures that can be implemented to protect buildings and communities from bushfires. This process requires an all-inclusive approach to management of risk. Some of the techniques that can be implemented to enhance community protection from bush fires include: Avoiding exposure to the hazards of bushfire Sitting and designing controls on development Minimizing the risk of fire by preventing ignition from the source Developing an engineering solution to minimize the risk of fire. Educating the community affected by the fire on the dangers of fire and how to go about it in case of fire outbreak. Availing the resources required for firefighting Setting up emergency arrangements to provide options for preventing the spread of fire Section 2 Building and Works Guide to standards BF4 sitting layout object The intensity of fire varies greatly depending on the Features of the surrounding topography. Crucial factors influencing the intensity of fire include the time frame a fire has to Develop and grow the fragmentation of vegetation cover, the quantity of vegetation, and the topography where the fire is burning. The bushfire risk on a particular site can vary significantly depending on the slope, arrangement and site of vegetation around the site the slope of the landscape can be used to help reduce the spread of bushfire within a development by siting buildings far away from ridge tops and steep slopes. The provisions of planning require that development avoid bushfire hazard and removal of vegetation where possible. The correct site location and siting of a new buildings is one of the most efficient and cost-effective ways of minimizing bushfire risk and need for vegetation removal Bushfire effects on development should be considered in The aspect of both landscape and the site it sits in. the strength of bushfire attack greatly depends on surface characteristics such as topography, fragmentation of the fuel on the surface and the type of fuel . These factors greatly affect the potential magnitude of a bushfire and the effect it may have. It is for this reason that the Standard BF3 requires the possible bushfire attack in regard to landscape fire behavior in consideration. Meeting the objective Development must be sited and located to minimize the increase in risk to life, community and property. Existing landmarks like roads, maintained open space dams, and other areas with less fuel should be sited between the bushfire hazard and the development. Other factors that should be considered include: Increasing the separation distance between the bushfire and the development Positioning, designing and aligning the building to reduce exposure to the possible bushfire hazard Implementing landscaping structures and the outline of the development Shunning ‘other’ fuel sources The developments should be located a level land close to public roads and far from the bushes. The effective way of avoiding the removal of vegetation is to select a site that minimizes the need for long routes and the need to remove the vegetation. Another strategy is to locate buildings in a way that they meet the requirements for defendable space. Defendable space for dwelling, industry office The Clause 52.47 of designing schemes states the requirements for defendable space and the associated construction levels for various types of constructions. These requirements Differ depending on the type of development desired the exposure of the development and its possible inhabitants, and the condition of the location. It is a requirement that all application must comply with the set objectives for siting, location, outline, defendable space, water, access and measures for bushfire protection. The main source of fuel for bush fire is the Vegetation. The survival of a building greatly depends on the location of the building and the amount of fuel available to propagate the fire. The effects of a bushfire can be minimized where vegetation has been changed and other sources of fuel removed from and around the development. This reduces the quantity of fuel available to enhance the burning process. Vegetation management does not mean the removal of all forms fuels. Trees and plants are beneficial in protecting the building from embers, intense heat and strong wind. Good ground cover is also essential for preventing soil erosion. Meeting the objective In case there is bushfire, a building that has complied with the requirements of the defendable space can expect a degree of flame impact from the fire front. Keen observations are required before any proposal based on this level is approved. It is expected that there are a few cases where this will happen. a proposal that complies with the BAL-40 defendable space will have to be supplemented by other possible site conditions such as low landscape bushfire risk, the egress and the type of occupancy. BAL-40 will not be taken into consideration where the building can be located to attain the BAL-29 or less. Recording your bush fire site assessment Attachment 4 of the DPCD template for recording a Bushfire Site Assessment uses north, south, east and west to classify the vegetation and slope and determine the required defendable space. On more complex sites (see Figure 17) the Bushfire Site Assessment should be refined to better reflect the shape, location and coverage of the vegetation and more Accurately consider the threat, including slope. Applying defendable space In regard to the worst case aspect for slope and vegetation, The defendable space should designed and maintained around the whole building as per the distances recommended in Clause 52.47 of the designing scheme. Where locating constraints occur and the landscape risk allows the size and shape of the defendable space to vary based on the threat from a particular perspective and a more comprehensive Bushfire Site Assessment. For instance, if the classifiable vegetation is woodland to the south-east, forest to the north-east, and grassland to all other angles, the shape of the defendable space neighboring the building may be responsive to the varying degrees of threat. Read More