Felling in High Hazards Stands
Background - Noggin INC1507 08/11/18
Conditions - The image to the left shows the forest, an un-thinned stand having large trees interspersed with smaller (wispy sub-dominant) or standing dead trees. The actual incident site was very steep with heavy undergrowth and undulating and broken ground. Following a period of rain, it was wet and slippery underfoot.
Qualifications and Planning - The two level 4 fellers (one newly certified under SafeTree) completed a morning meeting and felling plan before restarting from where they had left off the day before.
Description - The fifth tree of the morning run, a dominant tree, was leaning across the face into an area occupied by some other standing trees. The tree feller scarfed the tree to fall away from those standing trees, however, during the back-cut the tree broke its holding wood and fell sideways. As it fell, it clipped a smaller malformed, standing-dead tree breaking off and shattering a hook-shaped limb in the process. A smaller part of that limb (see image) flew back and struck the feller in the chest area, fracturing two ribs.
Contributing Factors - The scarf showed the top and bottom cuts not meeting and aimed too far to the right. Both factors made the tree susceptible to break its hinge wood and to fall sideways.
The wing-cuts, which are preferably placed at a 60 - 90° angle to the trunk, were placed at 30 degrees to the trunk and were deeper than the recommended 10cm. These cuts would have also compromised the hinge wood. See BPG Tree Felling p. 38.
The feller completed some clearing of the undergrowth, however, clearing one or two more of the smaller native trees would have provided extra visibility of the aerial hazards. This would have provided a clearer view of the standing dead tree enabling the feller to conclude that he should first clear this tree.
Finally, the feller had not cleared any undergrowth along the escape routes i.e. at 45 degrees to the stump. See ACOP p. 68. In fact, the feller was struck while standing approximately 2 meters from the stump, at right angles to it. Please address these practice issues with your tree fellers.
View this article in Safety Bulletin 116