Thomas Larson 10:30 a.m., Aug. 20
- Community Blog
- Encanto Gas Holder
SDG&E Computer Model Failed to Predict 2007 Rice Wildfire
Utility's Vegetation Management Program Ignored Inspector Warning to Trim Tree
A San Diego Gas & Electric Company employee testifed before the California Public Utilities Commission (CPUC) regarding causes of recent wildfires and contractor involvement in county tree inspections around power lines before the 2007 Rice wildfire. Despite a warning from a contracted "tree pre-inspector" regarding tree FF1090 that was entered into SDG&E's automated tree inventory system, no action was taken because SDG&E never got an additional memo.
Tree FF1090 limb failure onto an SDG&E power line has been cited as the alleged cause of the Rice wildfire.
Don Akau, SDG&E Vegetation Management Program manager, testifed that he was "ultimately responsible for the automated tree inventory system utilized by SDG&E and SDG&E's contractors to ensure that data input and system utilization is timely, accurate and complete." Akau further stated that "SDG&E had no reason to suspect prior to October 22, 2007 that any portion of tree FF1090 had a structural defect."
In follow-up questioning before the Commission, Akau agreed that he was aware of allegations "that tree FF1090 should have been trimmed within three months of July 18, 2007 because the Davey Resource pre-inspector selected the '0-3 months' drop-down option for 'months to next trim' and has since testified that he did so because he believed tree FF1090 might encroach within 4 feet within three months of his inspection."
Akau said SDG&E never got the separate memo that was required under SDG&E policy for immediate trimming that is not otherwise predicted by the tree inventory system in SDG&E's computer model.
In the field of information technology, it is axiomatic among experienced systems analysts that requiring multiple data input streams for the same information going into any complex system is a key component for generating systemic errors that could have been avoided through better initial design. A system used for predictions of liabilities that fails to process critical data is generally considered to be inadequate or dangerous. Testimony to CPUC by SDG&E's Debra Reed and other investor-owned utility executives in the 2009 Wildfire Expense Balancing Account (WEBA) application declared that wildfires are a necessary evil in electricity distribution.
Akau testified at length about SDG&E's ability to predict tree growth. Not included in Akau's testimony, nor in the testimony of other SDG&E witnesses before the CPUC were the effects of extended drought and insect infestation leading to tree disease or death that are not considerations in the VMP tree inventory system computer model.
According to CPUC Commissioner Timothy Alan Simon in an earlier press release, "The CPUC will respond appropriately to the wildfires after CPSD completes its investigation into the role overhead electric lines played in the wildfires." The Commissioner's statement continued: "Rule changes regarding transmission lines may be necessary. In order to know exactly what we need to do to improve safety, we need to have all the facts regarding the San Diego fires.
It is only this blogger's opinion, but the current move by SDG&E for cutting power to consumers during high dry wind conditions is apparently just a work-around for the inadequacies of its current tree inventory system computer model as a predictor of wildfire conditions by specific location.