Cudlee Creek Fire
Total Page:16
File Type:pdf, Size:1020Kb
Bushfire Investigation Cudlee Creek Bushfire (20 December 2019) Office of the Technical Regulator Preface This technical investigation report has been prepared by the Office of the Technical Regulator (OTR) pursuant to the objectives, powers and functions conferred on it by the Electricity Act 1996. Specifically, these include, amongst other things the monitoring and regulation of safety and technical standards in the electricity supply industry and the administration of the provisions of this Act relating to the clearance of vegetation from powerlines. 2 Contents Summary ................................................................................................................................................. 4 Introduction ............................................................................................................................................ 5 Scope ................................................................................................................................................... 5 Objectives............................................................................................................................................ 5 Methodology ....................................................................................................................................... 5 Background ......................................................................................................................................... 5 Declarations ........................................................................................................................................ 7 Technical Investigation ........................................................................................................................... 8 SAPN and CFS Site Observations ......................................................................................................... 8 OTR Site Observations ........................................................................................................................ 8 SA Power Networks Incident Report .................................................................................................. 9 SAPN Protection Equipment Operation ............................................................................................ 10 LiDAR Information ............................................................................................................................. 10 Google Earth Image Review .............................................................................................................. 10 Electricity (Principles of Vegetation Clearance) Regulations 2010 ................................................... 10 Prevailing Weather Information ....................................................................................................... 11 Findings and Conclusions ...................................................................................................................... 12 The Fire Source ................................................................................................................................. 12 Auto Circuit Recloser Operations ...................................................................................................... 12 Vegetation Clearance ........................................................................................................................ 12 3 Summary On Friday 20 December 2019 during severe fire conditions a fire commenced in the vicinity of Hollands Creek Rd, Cudlee Creek, which quickly spread through the Adelaide Hills, causing loss of one life as well as destruction of numerous houses and other assets. In cooperation with the Country Fire Service (CFS) and SA Police (SAPOL) the OTR established the likely cause of the fire start as a tree that had fallen onto an 11 kilovolt (kV) powerline. The point of ignition was adjacent to a pine tree plantation near Holland Creek Rd. The base of the tree that fell was approx. 6.8m horizontally away from the closest conductor. The tree was estimated to be 24m high, hence making it possible for the tree to contact the powerline when it fell over. As the agency responsible for the monitoring and regulation of safety and technical standards in the electricity supply industry the Office of the Technical Regulator (OTR) reviewed the incident to assess if breaches of the Electricity Act 1996 had occurred which might have contributed to the fire start. From the evidence observed on the site and review of information provided by SA Power Networks (SAPN) the OTR determined that the tree that fell was at a distance greater than the minimum clearance distance required by the Electricity (Principles of Vegetation Clearance) Regulations 2010, however due to its height it was able to contact a conductor when it fell. The OTR could not identify any indicators that could have enabled a reasonable person to identify this tree failure prior to the event. Based on the findings of this investigation the OTR concluded that no further technical investigation into this incident regarding electrical infrastructure is warranted. 4 Introduction Scope This report details the findings of a technical investigation by the OTR of the causes of and contributing factors to a fire that originated at a location along an 11kV electricity line with the feeder ID GU43. The location is approx. 6.5km north‐west of Lobethal. The investigation details the evidence gathered to support the technical conclusion reached and outlines the relevant standard that applies to vegetation management near the distribution network at this location. Objectives The OTR’s objectives were to: Establish whether electrical infrastructure played a role in the cause of the fire; Determine whether relevant technical standards had been maintained; Assess if relevant procedures had been followed; and Provide assistance to other investigating agencies, such as SA Police and the Country Fire Service. For the investigation the OTR took the following information into account: Information provided by SAPN: o Investigation Report o Email correspondence OTR site visit and observations Discussions with investigators from SA Police and CFS Google Earth images Methodology As part of their investigation the OTR undertook the following actions: Requesting and reviewing specific information from SAPN, including their investigation report and reports on the operation of protection equipment Assessing the information provided against relevant requirements, including legislated clearance distances and relevant operational procedures Visiting the location of the fire start, measuring distances between powerlines and vegetation to establish if any breaches of vegetation clearance zones had been likely prior to the fire Meeting with the CFS to seek independent confirmation on the likely cause of the fire A review of Google Earth historic images Background On Friday 20 December 2019 during challenging weather conditions with elevated temperatures and high wind speeds a fire started near Snake Gully Rd, Cudlee Creek. With a very high level of certainty it was determined that a pine tree had fallen onto an 11kV powerline, which started the fire that quickly spread throughout the Adelaide Hills. 5 Figure 1: Fire Start Location For the purposes of maintaining legislated distances between vegetation and powerlines the area where the fire started is classified as a “bushfire risk area” as defined in regulation 3 of the Electricity (Principles of Vegetation Clearance) Regulations 2010. Figure 2: Bushfire Risk Classification under the Electricity (Principles of Vegetation Clearance) Regulations 2010 6 Declarations A Total Fire Ban and Catastrophic Bushfire Fire Danger Rating for the Mount Lofty Ranges had been declared by the CFS on 19 December 2020 at 4:22pm.1 A Bushfire Advice Message was first issued by the CFS at 9:22am on 20 December 20202, and quickly escalated to an Emergency Warning Message for a fire burning in catastrophic bushfire conditions3. The Bureau of Meteorology on 19 December issued the following advice at 4:32pm for the following day: Forecast for Friday 20 December: Very hot. Afternoon cool change. Cloud developing with dust haze possible in the late morning and afternoon. Slight (30%) chance of a shower or thunderstorm in the afternoon and evening. Winds northeasterly 30 to 45 km/h increasing to 50 km/h before shifting south to southwesterly 30 to 45 km/h in the late afternoon. The CFS information combined with the BoM’s weather forecast for 20 December 2019 resulted in a forecast SA Power Networks Fire Danger Level Rating of FDL2. 1 https://www.cfs.sa.gov.au/site/home/criimson/cfs_fire_ban_and_fire_danger_rating_issued_19_dec_162400 03552.jsp 2 https://www.cfs.sa.gov.au/site/home/criimson/advice_message_cudlee_creek_issued_20_dec_09230003563. jsp?display_expired=t 3 https://www.cfs.sa.gov.au/site/home/criimson/emergency_warning_message_cudlee_creek_issued_20_dec_ 09330003565.jsp?display_expired=t 7 Technical Investigation SAPN and CFS Site Observations Following an initial investigation by the CFS it emerged that SAPN’s infrastructure had likely been involved in the fire start, prompting an internal investigation by SAPN. Both SAPN and the CFS have confirmed to the OTR that the likely cause of the fire had been a pine tree from a plantation that had fallen onto an 11kV powerline. Evidence gathered by the CFS and SAPN and sighted by the OTR appears to strongly support