A safe haven for emergencies – or a comfortable place to sleep in the snow
The idea of sleeping in the snow can be met by scepticism by people who have never tried it. The fact is that a well-built snow bivouac is an excellent alternative for accommodation. It is quiet and protected from the wind and, compared to staying in a tent, it is also relatively warm since the temperature in the bivouac usually is only a few degrees below freezing. However, the bivouac can become a necessity if you are trying to seek shelter from bad weather. Go out on a nice day and practice digging one. Just like for everything else, practice makes perfect – and when the wind is howling might not be the best time to consider different digging techniques.
An emergency bivouac must be built quickly. Skis, poles and a wind sack may supplement the basic construction material, snow. It is also important to use the probe to determine how deep the snow is. One basic error that many beginners make is that they dig the ditch and then try to prepare the barrier. It is much better to form the barrier while you are digging – a technique which means that the longer you dig the more protected you will be.
• The simplest type of emergency bivouac is a small hole that a person can lie in, which is often the only alternative in places where the snow is not very deep. Skis, poles and the wind sack are then placed across the top of the hole. It is not particularly comfortable, in other words, but at least you will be protected from the wind and snow.
• If the depth of the snow allows it – you will need at least 1.5 metres – an emergency bivouac that you can sit in is a more comfortable alternative. Skis and poles are placed across the top like beams and a wind sack is laid on top. Put snow on the roof and use a backpack as the door.
• If you can find a snow drift, it will be much easier to dig. When building an emergency cave, you take advantage of the slope and dig "inwards", using the same technique as when building a real snow bivouac. An advantage of this type of emergency bivouac is that it can be extended if you need to stay for a longer period of time.
Practice is the only way to learn
It is, of course, impossible to learn how to build a bivouac by merely reading some instructions. You need to practice out in the snow, preferably under the guidance of someone with experience. Many mountain stations arrange courses and independent organisations also offer mountain safety courses that include how to build a bivouac. Take one of these courses and then, on a beautiful day, go out with your family or friends and build a "snow cave".
Even if we cannot go into detail here about how to build different types of bivouacs, there are several safety aspects that are worth highlighting:
• Never dig in a high-risk avalanche area. While digging, you need to make sure that your equipment is not lying somewhere where it can be easily buried by collapsing snow.
• If you are digging in a drift, choose a high location so you can see over the edge. If it snows during the night, you will be able to get out by digging straight up. If you are further down in the ravine and several metres of snow drifts in, you will not have much of a chance of digging yourself out.
• Make some ventilation holes, about 10 cm wide, straight up with a pole. Let the pole sit in the hole so it can keep the hole clear if it snows. The ventilation holes are to allow fresh air to come in and regulate the temperature.
• There is enough oxygen in the bivouac; oxygen is found in the space itself and in the surrounding snow. However, if you stay for a longer period of time, you should occasionally scrape away the ice that builds on the wall and the inside of the roof to prevent a deterioration in the ventilation.
• Building a "gothic style" bivouac, i.e. with an arched roof, decreases the tendency of the snow to sink inwards in warmer temperatures.
• If the inner temperature of the bivouac becomes so high that the snow starts to melt, you should expand the ventilation holes or open the entrance so the temperature returns to below freezing.
• Due to the risk of carbon monoxide poisoning, you should not prepare food inside a snow bivouac. Heat water and fill thermoses and hot water bottles outside.
In addition to the tips listed above, you should remember to try to keep your clothes and equipment dry and free of snow. For example, it can be a good idea to place a ski next to the wall to make sure that you do not roll into the wall while sleeping and get the sleeping bag wet.