It doesn't matter where you are in North America, ice on the roads or on the lakes can be hazardous. Even in Southern states like Arizona, ice can be a problem at certain times of year. The seasons in North American are marked by distinct landscape changes, but some of these changes can be deceiving, which can make judging safety around ice tricky. The seasons also signal changes to the workforce and occupations, since the coming of cold and ice is a hazard across almost every industry that works outdoors in the winter. Here are some tips for winter and ice safety. (Staying safe often means taking personal responsibility. Read more in The 2 Biggest Challenges to Staying Safe.)
Life or Death SituationsWinter conditions can pose some unique life-or-death scenarios. This could mean crossing beaver ponds, lakes, sloughs and wet patches, so it is important to have a solid understanding of ice safety, and what the hazards are when working around water with thin or variable ice. To put this in perspective, I was working in the CNRL Horizon’s project in the Winter of 2007 locating pipes using a radio scanner to test for anomalies. While walking in waist-deep snow, I took a step forward and felt the ground give way beneath me. As I am quite agile, I jumped back only to see a vehicle-sized area of snow fall away like a cornice into a running stream of affluent and water products. If I would have been a second slower, I would have been swept away into this underwater torrent and would have either drowned or died of hypothermia.
In other words, many of the hazards presented by ice are largely invisible. That means that workers need to be extra-vigilant in the winter months.
Ice ThicknessIce thickness is one of the key things to keep in mind while walking outdoors in the winter, assuming you know you are crossing ice. The chart below shows the minimum thickness of ice required for the passage of a person, people or vehicles.
Keep in mind, however, that just because others have been driving or walking on the ice doesn't mean it's safe, although it can provide some clues and reassurance. Check for tracks to see if there has been lots of activity in the area recently. Also be on the lookout for areas that have been flagged as hazardous.
Water Cycling, Pumping and RunoffIn the oil and gas industry in particular, many facilities pump off excess water, which can flow underground, under an ice sheet, or under the snow, and can cause underground pathways. These are invisible hazards, so it's important to be aware of areas where these activities are taking place as much as possible.
Similarly, running water such as rivers and streams freeze differently than water that is stationary. Since water in motion has greater levels of energy, the particles do not freeze as quickly as those of stationary water, and should only be crossed after checking the thickness, and scouting for possible crossing points.
Aerated Ponds and LakesSimilar to the theory of running water, ponds and lakes that are aerated will have less ice near the aeration zones because air bubbles can get trapped under the ice causing thickness differentials. These areas should be properly marked and flagged, and ponds and lakes with aeration systems usually post warnings to ensure people are aware of the potential hazard.
Snow, Ice and StrengthEver wonder why the Inuit use snow for their igloos? It's because snow is a great insulator of heat! What that means is that ice under snow is much warmer than ice that is exposed to the frigid winter air and may be more fragile.
There may be external sources of heat that make ice more fragile as well. For example, if you are working around pipelines that are moving hot liquids, it is not uncommon for the ice to be much thinner around pipeline crossing areas. If at all possible, avoid crossing ice that is adjacent to a pipeline crossing.