Tuesday, 11 October 2016

Hockey On Turf

Ever wonder how something flat like a hockey surface is installed on a football field made of astroturf or fieldturf? There are some distinct differences that turf has when compared to grass, so putting down some ice over top of the turf requires some special savoir-faire when it comes to achieving an NHL-suitable rink. The image above taken by Braeden Jones of the Metro Winnipeg shows some of the early stages of how they get the substrate down that makes good ice, but I'm going to walk you through the five layers of work that go into making a Heritage Classic rink on turf!


This is what you're seeing being installed above on top of the turf at Investors Group Field. Because turf is spongy and somewhat uneven in relation to its surface when compared to concrete, a solid substrate must be put down by the ice crew in order to make the surface as flat as possible. The Armour Deck is made of plastic, and provides a stable base on which the next four layers can be built.


These are panels with tubes running through them so that refrigerant from the refrigeration truck is run underneath the ice surface to keep it solid. The coolant used in the refrigeration truck is glycol coolant which also helps to reduce the effects of corrosion in portable systems that are occasionally opened to the air. As much as 3000 gallons of glycol can be used in the piping system, so the rink should stay icy for a while even if it's warmer than freezing out. The unit that drags around the refrigerant will set you back about $850,000 while holding some 3 tons of coolant!

On an indoor rink or NHL rink, the pipes are usually embedded in the flat concrete surface onto which ice base layer is installed. What Mike Craig's crew does is replicate that effect with these ice panels containing the piping and coolant. The other major difference is the coolant used indoors is calcium chloride which is more energy efficient for indoor use. However, if it isn't kept in check, this substance can become highly corrosive. This is why glycol is used in portable systems such as the NHL's portable ice system.

Layer 3: ICE BASE

Once the panels are in place and the cubes have been connected to send coolant through, the ice crew begins to spray a half-inch thick layer of ice as the base of the rink. This is done slowly and methodically to ensure a flat surface, and many individual layers are added throughout this process. Hoses are usually set to a fine spray as well to ensure that freezing is done uniformly. When you see chips out of the ice, it's usually the ice surface layer that has come off. The base is generally dense and very firm similar to what one would do for a backyard rink.

One must remember that if the water is applied to quickly or the layers become too thick, it becomes harder to keep the ice surface frozen since more energy is used. The NHL isn't interested in running up a massive power bill for one game, so the half-inch thick layer is the ideal thickness of the base layer to keep the surface layer icy. That half-inch layer is still some 7/8" thicker than the bottom layers seen in NHL rinks as illustrated just above this line, so you can see just how much water is needed to ensure a safe playing surface when moving games outdoors. Half an inch of ice is a very solid base layer.

Inside this base layer will be where the heart of the ice-making technology lies as well. Eight individual sensors will be installed in the ice that will monitor everything from the temperature of the ice to how much snow comes off to how much water goes is put on via the Zambonis. All of this information is relayed to Craig and his team via their cell phones, so expect them to be staring down rather than at what's happening on the ice during the game!


The white wash is literally the painting of the ice white for contrast with the puck and to hide the layers underneath the ice surface. For simplicity, this is usually done with some sort of paint applicator where a fine mist of paint is used to ensure a flat surface once more. Once the ice is a white opaque surface, another fine layer of water goes over top to set the white wash. Once this layer has frozen, lines, logos, face-off circles and dots, and advertising can be applied to the surface. This is when the ice surface begins to look like the finished product!


As seen in the illustration above, the normal thickness of the ice is about an inch thick. The NHL applies more water for the outdoor games, making the final layer anywhere from a half-inch to three-quarters of an inch thick. Once this layer is applied and determined to be the consistency, the Zambonis are responsible for maintaining this ice surface. The white layer, logos, lines, and everything else are deep enough into the ice surface that they won't become exposed if someone cuts hard on where they are found.

In learning about ice preparation, one line stuck with me the entire time: "The less water you put on the floor at one time, the better your ice will be." If you're asking yourself why the NHL would be setting the ice up some eleven days before the event takes place, Mike Craig and his crew seem to follow the same adage. They work methodically to create the best ice conditions they can for outdoor games, but the one factor they cannot control is the weather.

When asked about ideal conditions on Tuesday, Mike Craig answered, "A nice cool day. Nice and cloudy. Everything's kind of calm. Not much wind. That's ideal."

All in all, Mike Craig and his ice crew of 20 people estimate they'll put down some 20,000 gallons of water for the Heritage Classic game, and he expects to have the ice surface ready by the end of this week! "Hopefully by the afternoon of (this Friday) we'll be spraying water and making ice out there," Craig told a scrum of reporters. "Everything so far is right on track, and weather-wise everything is right there as well. We're not anticipating any major issues coming up. We just wanna make sure we're putting on a good event, a good show, and away we go."

All of Canada, and especially Winnipeg, is expecting a great show, and the atmosphere inside Investors Group Field will be raucous with the Oilers in town to play the Jets. While Mike Craig has faced challenges in other cities when it comes to the weather. With highs of 8°C on Saturday, October 22 and 7° on Sunday, October 23 with little chance of rain, it appears the rink will be perfect to host the 2016 Tim Hortons Heritage Classic!

Until next time, keep your sticks on the ice!

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