Innovation September-October 2013

harvesting operations, and other infrastructure. Managing snow avalanche risk has several key elements. The first is to establish the context of the operation. What are the operational goals of the enterprise? Can they be met if there is avalanche risk involved? What are the elements at risk? Are there other risks involved? What must be done to manage the risk? The second step is to identify areas where avalanches could naturally occur or, through human effect (e.g., logging), occur in the future; this requires considerable expertise in detailed, polygon-based terrain mapping and runout analysis. Below the timberline, this is relatively easy to do; however, where old-growth forest is not present, other methods must be employed. Detailed observations of where avalanche transported colluvium and damaged vegetation are present can be

Rescuers use shovels to dig out railroad workers buried in a 1910 avalanche in Rogers Pass, BC.

It was the North Route accident that prompted the Ministry of Transportation and Infrastructure to introduce the Snow Avalanche Program, which uses avalanche technicians stationed at eight key locations in British Columbia, and a sophisticated network of weather and snow observations stations, to maintain a careful watch over 62 avalanche-prone areas along BC’s highways. The program has an impeccable safety record and also an excellent record of managing hazards so that closures and inconveniences to the public are minimized. The excellent safety record of the Ministry of Highway’s Snow Avalanche Program illustrates that areas of potential avalanche activity can be readily identified and managed. In order to meet the safety requirements of WorkSafe BC and to be consistent with the APEGBC Code of Ethics, engineers and geoscientists have a responsibility to ensure that projects in other avalanche-prone areas are well managed, both with regard to the safety of people and the integrity of infrastructure. Currently, the energy, mining, and forestry sectors in British Columbia are most in need of ensuring that project elements and work areas in avalanche- prone terrain are acceptably managed. The elements at potential risk include access roads; penstock alignments; transmission lines; pipeline routes; and related facilities, such as work camps, water intakes, powerhouses, compressor stations, mining plants,

used in conjunction with a statistical analysis of the likely runout distance of an avalanche to define areas of potential hazard for a given return period. The third element of an avalanche management strategy is to analyze the risk for each slide path: how often avalanches are likely to occur, and if they do occur, what impact they would have on personnel, infrastructure, environment, project schedule, etc. In this regard, a decision also needs to be made as to the level of risk that will be tolerated. For example, a permanent, inhabited structure may require that a 300- year return period be used; whereas, for a power line, a 30- or 50-year return period may be acceptable. Where people are likely to be involved, the risk acceptability threshold also depends on how long someone is exposed to hazard. As avalanche hazard can change very rapidly, an ongoing method for hazard evaluation is required. Typically, a daily prediction is made of the likelihood of an avalanche of a given size to occur within a given time period. Local and regional weather forecasts combined with snowpack data are the basis on which qualified avalanche personnel are able to provide daily avalanche hazard forecasts. Weather models, such as the National Atmospheric and Oceanographic Administration’s (NOAA) Global Forecast System (GFS), as well as other publicly available and private weather products, are one of the primary tools used. Site specific weather and

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