We are working on our 48th skating season. Did you know that the NCC has been maintaining the Rideau Canal Skateway since 1971? It first opened after a team of NCC employees, armed with brooms and shovels, cleared a small section of ice near the National Arts Centre. Over time, the length of the Rideau Canal Skateway grew, as did our knowledge of the science of ice.
My team at the NCC cares for the Rideau Canal Skateway. And with the Skateway holding the official Guinness record for the world’s largest naturally frozen ice rink, this is not a small task. Our crews work around the clock to maintain the ice, and provide top-notch facilities and services for the more than one million people who visit the Skateway each year.
From water to ice
We start work on the Skateway well before the skating season. In mid-October, Parks Canada drains the Rideau Canal by opening the sluice valves at the Ottawa Locks near Parliament Hill.
We then install:
- 4 change rooms
- 4 restrooms
- 35 sets of stairs
- 3 vehicle ramps
- 5 universal access ramps
- beams at the locks to raise the water to skating level
When the cold weather first arrives, we allow nature to do its work. As the water in the canal begins to cool, it contracts and the level drops. Once the water reaches a uniform temperature of 2°C from surface to bottom, it begins to crystallize and expand. Because ice crystals are less dense than water, they rise to the surface, where they eventually form a frozen cap.
Understanding the process of ice formation helps us create and maintain the ideal surface for skating.
Once a layer of ice has formed, the drilling team uses an ice auger to draw out core samples of the ice. We use the “ice carrot” to measure thickness and check ice quality. When daily testing shows a sufficient thickness (30 cm) of good quality ice for safe public skating, the green flags go up, and entrances to the Skateway open.
White ice and clear ice
Depending on the weather, different kinds of ice form on the Rideau Canal Skateway. There are two main types of ice: clear ice and white ice.
Clear ice provides the ideal skating surface, because it has fewer air bubbles and is much stronger. It is colourless, and it forms naturally when temperatures are cold enough for crystals to form below the frozen surface. Since the early days, we’ve relied on the ice saftey guidelines established by Dr. Nirmal Sinha, who is a scientist with the National Research Council Canada and a world leader in the science of ice. According to Dr. Sinha, a depth of 30 centimetres of clear ice is required before the Skateway can open to the public.
White ice is cloudy and contains many air bubbles. It forms when fallen snow becomes soaked with water and freezes. There is also a type of white ice that can be made by flooding the surface of existing ice. In 2007, we engaged BMT Fleet Technology to further our knowledge and fine-tune our process. They conducted a study and found that flooded ice, under certain conditions, can be as strong as clear ice. With this flooding process, the thickness of ice needed for skating can be created more quickly at the beginning of the season.
Partnerships with leading ice experts keep us at the leading edge of ice maintenance. This expertise makes for better ice conditions and greater safety for skaters. I’m proud to say that we now have the in-house expertise to continually improve the ice on the Skateway.
A weighty issue
Not only do we monitor the thickness and composition of the ice, we also make sure that there is not too much weight on the ice surface. Keep in mind that the Skateway is a free-floating sheet of ice on a body of water. The weight of crowds, snow and snow removal equipment must be dispersed for the ice to remain safe. The ice inspection team monitors the vertical movement of the ice. If the ice sinks, it means there is too much weight on its surface at that location.
People often ask me what I consider to be the enemy of ice. My answer is snow. When snow is allowed to accumulate, it forms an insulating blanket over the ice and eats away at the ice surface. The weight of the snow also depresses the ice surface. That is why, after a snowfall, the maintenance crew is quick to get to work on the Skateway with snow blowers and snowplows to clear away the snow.
Just removing the snow is not enough to turn the Rideau Canal into the world’s largest skating rink. After the snow is cleared away, the ice surface is swept and flooded to smooth out the cracks. This process is repeated each night, weather permitting, to provide a safe skating surface just in time for the early morning skaters.
Here’s to another great season on the ice!