The Big Chill

The Big Chill
November/December 2015
Making NHL hockey ice is a combination of engineering, chemistry and artistry.

The Vancouver Canucks were blanked 4-0 by the San Jose Sharks in a pre-season September game on the newly minted ice surface at Rogers Arena.

The Vancouver Canucks were blanked 4-0 by the San Jose Sharks in a pre-season September game on the newly minted ice surface at Rogers Arena. Photo credit: Jeff Vinnick

Is hockey the greatest sport on earth? Few Canadians would disagree. In terms of speed and intensity, hockey is unmatched by any other game. It is also the consummate team sport. A win is impossible unless every player works together, each athlete giving — as the cliché goes — 110 percent.

But behind each of the National Hockey League’s 30 teams is another, equally important group: the men and women who create and maintain the vast, glittering, icy canvas where games are won and lost, blood spilled and history made. At Rogers Arena in downtown Vancouver — home of the Canucks — there is, of course, the rink where the action happens. Encircling it is an area that few fans ever see: a rubber-floored, oval labyrinth that houses dressing rooms, offices and an assortment of machinery, loaders, equipment and computer and security stations. This is where the all-important ice making and maintenance happens that ensures not only a fast and fierce game but player safety; athletes  can give that 110 percent without risking a career-ending injury from catching a skate in a rut. 
It’s mid-September and Al Hutchings, director of engineering with Canucks Sports & Entertainment, walks briskly down the curving hallway. “I love this time of year, it’s so full of promise,” says Hutchings, smiling enigmatically when asked about the Canucks’ prospects for the 2015-2016 NHL season. 

Delphic predictions aren’t Hutchings’ forte. Ice, however, is. But when it comes to the minutiae of making a perfect 1,830 square metre polycrystal plane, even Hutchings defers to the man he says the NHL calls whenever a problem with ice arises. This is Mark Wohl, manager of plant operations at Canucks Sports & Entertainment who, at this moment, is standing outside the rink with Hutchings, watching as staff crouch down at centre ice beside paint cans, filling in the Canuck’s stylized orca logo. It’s a Monday — two days after Rogers Arena rocked out to a Foo Fighters concert. The morning after the concert, crews began cleaning the concrete arena floor (scrapping up chewed gum is one of their more onerous tasks). The key step, however, began even sooner. Immediately after the concert, cold fluids began flowing through a web of piping embedded in the concrete foundation. By Saturday morning, the temperature of the arena floor surface had decreased to –8 C from 22 C — cold enough for ice making to begin. This is not the backyard winter flooding that Canadians remember from childhood. It will take five days to spray 70 layers of water — enough to create a 3.17 centimetre-thick block — onto the arena surface before the Canucks kick off the first practice of the season on home ice.

Mark Wohl, the manager of plant operations at Canucks Sports & Entertainment, is considered one of the top hockey ice experts in the NHL.

Mark Wohl, the manager of plant operations at Canucks Sports & Entertainment, is considered one of the top hockey ice experts in the NHL. Photo credit: Jeff Vinnick

The ideal temperature for Rogers Arena ice is –6.7 C. Any warmer and a hockey game itself might be impeded, slowing down players and making the puck bounce, rather than glide, across the  ice. This brisk temperature is maintained by circulating 22,500 litres of very cold brine water containing calcium chloride as the antifreeze agent through the pipes. During games, the computerized control centre at Rogers Arena is set so that if the ice increases even one degree above the set point, the building’s compressors kick in to start the circulation of refrigerated brine beneath the ice surface. The brine runs through 15,727 metres of steel piping — the approximate distance between Vancouver and the nearby city of Richmond — that is encased five centimetres below the surface in the 10-centimetre thick concrete floor. It’s not ordinary concrete either, but a special blend that tolerates expansion and contraction caused by fluctuating temperatures, Wohl notes. 

In the world of hockey, refrigeration and ice have a long relationship. In 1876, the world’s first refrigerated ice surface opened in London, England. In Canada, two British Columbian brothers, Frank and Lester Patrick, backed by their father Joe’s lumber money, built indoor ice rinks in Vancouver and Victoria in 1911 utilizing a refrigeration system.

Cold concrete means that ice making can begin. A 3.5-metre spray bar is manoeuvered by hand around the 61-metre long and 26-metre wide rink, distributing an even layer of water. The layer is so thin — about 0.8 centimetres — that it freezes virtually instantly. Half a dozen layers of water are sprayed, creating what Wohl calls “black ice” because the dark concrete shows through. In order to make the pristine white that contrasts so sharply with the small black puck, helping fans follow the play, the next layer is painted with Jet Ice Super White 3000 paint, specifically formulated to create an intense, bright surface. Once the painting is finished, it is sealed with several more thin layers of water. The process, says Wohl, “is labour intensive. What we’re doing has been the same for years and years. There’s been no real change except for a bit of technology.”

The next step is measuring out the blue and red lines delineating the neutral and end zones, the faceoff circles and dots, hash marks where the players stand, goalie creases and the team and corporate sponsorship logos. Circles are painted with a pre-measured circle maker. The painting process, says Wohl, takes about eight hours from start to finish. 

Water, of course, is the raw material that makes the hockey ice. But can the ice-making team just turn on the tap and start spraying? Vancouver is known for the purity of its water, which is sourced from three remote natural mountain reservoirs: Capilano, Seymour and Coquitlam lakes. Because spring runoff from melting snow packs is quick, the water doesn’t sit on a land surface absorbing minerals such as calcium and magnesium. In comparison, the Calgary Flames use water obtained from sources containing high levels of total displaced solids, which must be removed to optimize that franchise’s hockey ice, Wohl says. 

Once several layers of ice are created, followed by a layer of bright white paint, then Steve Caron can get to work painting a perfect faceoff circle. After creating the lines and logos, crews will work for another two days spraying water layers­ to create the final smooth polycrystal plane.

Once several layers of ice are created, followed by a layer of bright white paint, then Steve Caron can get to work painting a perfect faceoff circle. After creating the lines and logos, crews will work for another two days spraying water layers­ to create the final smooth polycrystal plane. Photo credit: Jeff Vinnick 

Despite having fewer minerals in the water than Calgary, Rogers Arena still uses a sand and gravel filter with progressively smaller openings of 25 micrometres (µm), one µm and 0.5 µm to remove possible impurities. (Other teams, like the Winnipeg Jets, use reverse osmosis to purify their water.) Once the reservoir water exits the filtering system, it is too pure to create hockey ice and minerals must be added, says Wohl. Without minerals, the ice will be too hard, making it difficult for the athletes to get traction. So why go through all the trouble of filtering them out? Because ice becomes soft if there is an overabundance of minerals, leaving it vulnerable to the shredding of players’ skates. To achieve the ideal balance, the best solution is to strip out the natural minerals, then add them back in at a composition and concentration that can be controlled. “We use a chemical that we have developed which I can’t divulge,” says Wohl. “It’s like Colonel Sanders’ secret herbs and spices.” This chemical cocktail, called Right Ice, works so well that the Canucks franchise sells the mixture to other rinks with the same problem, Wohl says, admitting that the ingredients are so basic they are available on store shelves. 

Finding the perfect mix of minerals and water is only one step to creating ice. The real work is done by the impressive mechanics of the refrigeration system. At Rogers Arena, the refrigeration plant is almost new, replaced a year ago at a cost of $1.4 million, says Wohl, dressed in the working man’s uniform of jeans, leather boots and safety reflector vest. “The original system was 20 years old, so we thought we might as well bite the bullet and rebuild it.” Like many NHL rinks, anhydrous ammonia (NH3) is the coolant used in the refrigeration system at Rogers Arena. (Some NHL rinks use halocarbon, or Freon, says Wohl.) It is stored under pressure in closed containers before being pumped into a tube-and-shell heat exchanger with the calcium chloride brine on the other side. When the pressure is released, the NH3 evaporates (at atmospheric pressure, ammonia boils at –33 C) and absorbs heat from the brine, causing its temperature to drop. 

The heat exchanger is strong enough to bring temperatures down to –16 C. (The calcium chloride (CaCl2) in the brine water prevents it from freezing.) During a game, two pumps constantly circulate brine through the refrigeration system, says Steve Good, who is part of the ice maintenance crew that also includes Steve Caron, Keith Fong, Wade McLennan and Gavin Hamblin. Advances in refrigeration technology meant that when the system was upgraded a year ago, the amount of NH3 needed for cooling the brine was reduced to 680 kilograms from 2,040 kilograms, Good says. This reduction means that the system is safer than the original one, when NH3 gas was stored on the roof. Today the refrigeration unit, which sits two floors below rink level, is a closed system. “No ammonia can leave the room,” Good says. NH3 leaks, while extremely rare, are dangerous because the gas burns mucous membranes. In 2011, an NH3 gas leak at the North Shore Winter Club in North Vancouver left Olympic silver medal figure skater and coach Karen Magnussen permanently disabled.

Steve Good works in the refrigeration plant at Rogers Arena, which is a closed system to prevent ammonia gas leaks. Rogers Arena uses anhydrous­ ammonia (NH3) as the coolant for absorbing heat from the brine circulating under the rink in order to sustain a perfect ice surface.

Steve Good works in the refrigeration plant at Rogers Arena, which is a closed system to prevent ammonia gas leaks. Rogers Arena uses anhydrous­ ammonia (NH3) as the coolant for absorbing heat from the brine circulating under the rink in order to sustain a perfect ice surface. Photo credit: Jeff Vinnick 

George Agnes, an analytical chemist from Simon Fraser University, says that refrigeration, in combination with the laborious process of layering the water, is what turns the ice into a smooth, clean “amorphous solid,” with layers that are “really well bound to each other, resulting in a single piece of ice.” The freezing of the water is a bottom-up process. This means that the cold emanating from below the ice freezes the bottom first, allowing gases dissolved in the water such as oxygen and carbon dioxide to be expelled during the freezing process and released into the atmosphere. This leaves the sheet of ice clear and free of frozen pockets of entrained gases. Agnes recalls his childhood days in Ontario, when his dad would create an outdoor rink by hosing down a portion of the driveway. Here, the freezing would come from the top down, as the atmosphere was colder than the ground on which the ice sheet was created. During the freezing process, those same dissolved gases became trapped in pockets under the shell of ice forming more quickly on top. “Wicked potholes were created so we always had to wear padding so that when we fell over these things we wouldn’t hurt ourselves. My dad tried to convince us that it made us better skaters,” says Agnes. If similar imperfections were present at Rogers Arena — even if they were small — the ice could possibly shatter in places, he adds.

Once the 82-game, regular season starts, maintaining the ice is an ongoing challenge. Every game, at least 0.5 centimetres of the 3.17 centimetre-deep ice is ground off by the two teams of powerfully built men flying along on steel blade skates at speeds nearly equal to that of a racehorse. But the gruelling games don’t present the only challenge to ice maintenance and Rogers Arena faces some that are unique to the NHL. For perfect ice, the stadium should be kept at 40 percent humidity, with the ice surface never going above –6 C. In Vancouver during hockey season — which coincides with the rainy season — outdoor humidity stays above 80 percent. It is virtually impossible, says Wohl, to maintain optimum humidity when the arena doors open and more than 18,000 fans surge inside. To counter this, Rogers Arena blasts its air conditioning system (there are no de-humidifiers in the building), opening the dampers to let humidity out, preventing the formation of fog on the ice. 

The role that the ice resurfacing machine plays in ice maintenance can’t be forgotten, says Agnes. And, once again, temperature is key. (Rogers Arena uses Olympias instead of the iconic Zamboni for resurfacing.) In NHL and community rinks, the ice resurfacer — Olympia or Zamboni — scrapes away a thin layer of ice about 0.2 to 0.4 centimetres thick between periods, says Agnes. The lost ice is replaced with water at about 75 C, which melts the first few layers of ice. The temperature allows the water to flow across the surface of the underlying ice, filling in ruts and holes and resulting in a smooth surface once again. “If they used cold water, it might freeze too quickly,” Agnes says. 

A flawless block of NHL ice is a thing of beauty. Keeping it that way requires a dedicated team whose artistry, patience, experience and vigilance preserve this clear, white cold canvas as the perfect foundation for a hockey team’s long and arduous journey to the ultimate NHL goal — the Stanley Cup.