Date of Event: 8/21/2017
Canyon involved: Big Cottonwood Canyon, Salt Lake City
Region: Ledgemere Picnic Area, Big Cottonwood Canyon, Utah
Country: United States
Submitted by: Sandy Crow
Source: Canyon Collective, First hand reports
Injury: Fracture
Cause: Anchor error, decision-making error/shortcut
Description of Event: Three canyoneers were at Ledgemere Picnic area, a crag in Salt Lake City often used for canyoneering practice sessions. They were practicing a guided rappel for an upcoming canyoneering assessment. After setting the top anchor, one participant rappelled down and the other two walked down. The three met at the bottom and discussed anchor options: a “bomber rock” they’d heard about but none could identify, a 3 foot tall dead tree trunk, and a huge rock laying on top of another rock at the river edge, creating a pinch point. Two of the participants had seen this last anchor successfully used at previous practice sessions and so the group settled on using that anchor. Doubled webbing was placed around the rock at a large pinch point, rigged with a Totem using plaquette mode, and the guideline was tightened. One of the participants then went up to descend the guided rappel. At the halfway point on the guided rappel the bottom anchor failed: the rock on top moved upward and out of place, causing the webbing, which was still intact, to come completely out and the rappeler to fall approximately 10 feet onto her back. She was able to walk after about 15 minutes and was driven to the hospital by one of the other participants. Her injuries included a fractured pelvis in 3 areas and a 50% compression in her L2 vertebrae. She spent a night in the hospital and was recommended to not work for a month and not canyoneer for 6-9 months.
Analysis
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The load on the guideline in a guided rappel is significantly higher than the load on the rappel line. The top and bottom guideline anchors must be very strong. The force on the anchors is greatest when the rappeler is at the mid-point of the guideline.
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Pinch point anchors may not be strong enough for a regular rappel, let alone a guided rappel. They must be thoroughly inspected and tested. Preferably they will be backed up for all but the last person on rappel. Pinch point anchors are generally last-resort.