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Candling Procedures Discussion paper   – Greg Harry March 2012

What is candling? Candling is the application of controlled fire to the bole (trunk) of trees either within burn units, or on fuel breaks for the purpose of reducing bark hazard. (East Metro Draft 2010)

What candling is not? Burning that removes more than the bark hazard and a limited amount of surface and near surface fuel around the base of the candled tree.

Driptorch Using the drip torch is more labour intensive and works best when Bark Fuel Moisture Content (BFMC) is at the lower end 10-13 %. The extent of your candling is not limited by flame thrower. reach or trafficable control lines GFF accreditation only required to operate.

Flame thrower The flame thrower is efficient and has great effect  when BFMC is at the higher end 13-15 %. Depth of your candling is limited to flame throw (approx 15 metres) Control line needs to be trafficable. Crews must be accredited to operate.

Outcomes •	The increased effectiveness of the control line •	The reduction of bark hazard enhances the future effectiveness of fuel breaks by reducing the potential for short distance spotting •	The reduction of bark hazard may reduce the Overall fuel hazard (Hines et al. 2010) within a burn unit to below its trigger point, potentially negating the need for further fuel reduction works. •	Pre burn candling reduces potential containment issues that may arise on the day of the burn when surface and near surface fuels are available to burn reducing the requirements for patrol crew during the next stage of the burn, freeing up crew for other tasks.

Candling procedures •	Candling can be done pre or post burn. •	Successful candling should remove bark for the entire tree height, but even the removal of 2-3 metres of bark from the bole can reduce the potential of the tree being involved in the next burning stage •	Candling can be conducted when the fuel moisture content of the BFMC is under 15% ODW with an ideal range being 12%-14%..The Fuel Moisture Content (FMC) of surrounding surface and near surface fuels should be above 18% •	For an effective session of candling plan for a minimum of 4 hours of less than 60% RH.

•	Candling can often be stand alone, or part of a 2 or 3 stage processes. •	Candling should only be conducted under conditions that limit the amount of surface and near surface fuels igniting from embers falling from treated trees •	The radiant heat generated by the candling process may cause the surface and near surface fuel surrounding the base of the tree to dry out and become available to burn. This may result in limited surface fire spread around the base of the tree. This is normal and assists in the convection process required to effectively candle. •	Candling operations need ongoing patrol over subsequent days until declared safe or they are incorporated into the next stage of the burn •	Where possible Candling should occur to a depth of 15 metres or equivalent of one tree height (whichever is least)

Risk Management •	As candling is a planned burn operation the requirements of the Fire Management Manual 10.1 Prescribed Burning apply so all operations must be supervised by an accredited and authorised Burn OIC with a Burns Controller in place •	A burn plan is required for all candling operations regardless of whether it is planned as a stand alone objective or part of a larger operation and •	Candling needs to go through the Department Burn plan approval process. •	Where appropriate QA sign off to be completed by Parks Victoria Chief Ranger.

Planning •	For candling to be safe it should be conducted when the FMC of surrounding surface and near surface fine fuels are above 18% Oven Dry Weight (ODW). For this to occur it is better to be 12months ahead in your planning. eg. To burn in autumn it is best to have candled  the preceding winter or early spring - this means the burn needs to be included the preceding years FOP. •	Where sites have been identified by Biodiversity or AAV (i.e. tree hollows, scar trees, nesting or roosting sites) through the FOP process, burn plan needs to outline protection measures •	 In the future consideration may need to be given to a reduced planning process for “candling only” operations

Control lines •	Under candling prescribed conditions the fuel moisture differential reduces the need for a mineral earth control line. If the fuel moisture content of surrounding surface fine fuels is greater than 18% ODW, and there is no stratum of near surface fuel adding to the fuel complex, then a mineral earth control line may not be required. •	Where a there is a vertically and horizontally continuous layer of live and dead near surface fine fuel greater than 10 cm high, then a 3 metre trafficable mineral earth control line is required

Prescription: No standard prescription currently exists for candling but experience and feedback suggest the following is applicable •	Temp <25C, RH 35% - 60%, Wind (@10m) <20kph, FDI <5, FFMC >18%, BFMC 10%-16%, drought factor < 3

Operational Considerations: •	When BFMC is below 10% spotting is extreme. •	For effective candling plan for a minimum of 4 hours of less than 60% RH. •	Objective for each stage of the burn to be clearly stated. •	Onsite FMCs of exposed surface and exposed bark must be taken before commencement. •	A test burn of the fuels surrounding the base of the tree should be conducted to verify that fine fuels are unavailable. •	Under candling prescribed conditions a light up crew and a crew to patrol is all that is required •	Burn OICs should limit the distance lit up based on the ability to patrol. •	Pre candling works such as excluding habitat trees by raking should be done on days you cannot candle. •	When measuring BFMC sample from the surface bark and test in the Wiltronic fuel moisture meter using brown stringy as the sample type

E.g. Objective for candling along the edge of a planned burn To reduce the bark hazard to Moderate to a depth of 20m along on the track from point A to Point B:, All identified habitat trees should be clearly marked and protected and should be excluded where possible from induced fire •	Flame thrower is available •	Flamethrower crew accredited •	Applicable signage •	Habitat trees clearly marked and protected •	Hollow or damaged trees, that would allow fire to establish, marked and protected •	Water supply available •	Daily patrols until declared safe Resourcing •	Ignition – BOIC, Flame thrower 2 accredited persons or 4 persons on drip torches •	Patrol 2 slipons  4 persons, •	Optional 1 tanker ,1dozer

Notifications •	Notifications to be as per the burn plan

For the future •	Research on appropriate drought factors for candling •	Research on BFMC

Bibliography The original “Candling Procedures”: East metro Fire District was drafted by Shane Vandenborn in 6th October 2010 and reviewed by Lee Gleeson 19th October2010

DSE (Hines et al.) (2010)  Overall Fuel Hazard Guide 4th Edition  Report No. 82. Fire and Adaptive Management, Department of Sustainability and Environment, Victoria.

Most staff would probably not bother to work out the Drought Factor anyway, and provided they take FMC readings with the Wiltronics before ignition on the day, this, along with a test burn, should be sufficient to ensure surface fuels will not carry continuous surface fire.