ANFO in Whitehorn IIPosted: January 17, 2009
Another beautiful sunny day at Lake Louise today, and the avalanche control team made use of the good visibility to try and get some results in E, F, & G Gullies of Whitehorn II. Previous attempts to get results with our regular 1kg and 2kg shots were unsuccessful, so we decided to pull out the big guns – ANFO, that is.
ANFO stands for ammonium nitrate and fuel oil, and comes in large bags. It looks like lawn fertilizer, and can be used to make custom size shots to fit the needs of the control team. In this case, three 7kg bombs were made by placing the ANFO in separate bags, then inserting a 1kg shot with fuse and igniter.
We loaded the lift around 8:30 and arrived at mid-station just as the sun was beginning to peek over the mountaintops. By the time we got to the top of Summit, Whitehorn II and the rest of the backside was bathed in a beautiful early-morning light. I travelled around to Shoulder Roll on Boomerang so I could get some photos of the action (if there was going to be any). The first two shots were used in E and F Gullies, and both produced very minor results – just a little surface snow around the shot placement.
The shot in G Gully was a different story. As shown in the photos below, as soon as the bomb went off, fracture lines appeared along almost the entire vertical length of the run, and the slope avalanched down to the bottom and up the other side of the terrain slump that runs along most of the bottom of Whitehorn II. This was a size three avalanche, enough to bury or destroy a car. One patroller was asked why Whitehorn II hadn’t been open yet, and the reply was, “Go ski Boomerang, then look up to your right and you’ll get your answer”.