Westmount, Que. opts to build first-ever underground arena

Westmount mayor Peter Trent, fresh from fighting a war as a former politician to successfully “de-merge” Montreal’s suburbs from what used to be the controversial “megacity”, returned to office in 2009 only to find a plan on his desk for a brand new replacement community arena.

The problem was the plan was all wrong. The plan was to build an even bigger arena than the old 1958 version. That wouldn’t do, particularly with the city wanting add-ons like an outdoor swimming pool and a terrace where people could sit outside and have a coffee. Also, in an age where the emphasis on green space is more important than ever, a better solution was needed.

So Trent and his council came up with the revolutionary idea of putting the expanded twin NHL-size ice rinks below the ground, eradicating what had been an eyesore and creating more parkland.

And Trent, who has a scientific and business background, thought an underground arena would also be practical.

“You don’t really want natural light because it melts the ice and furthermore ice 30 feet down remains the same temperature all year round. So, it means, you can keep at least one of the rinks open during the summer with very little expenditure of energy,” he said.

The result is what’s believed will be the only ice arena in the world to be below surface.

The rinks will sit 10 metres underground but while innovative for a sports complex — the site is known as the Westmount Recreation Centre — it’s not a whole lot different from engineering a below grade parking garage. Pierre-Luc Dumas, vice president of general contractor Montreal-based Pomerleau Inc. — a firm with wide experience in arena design and build — likened the structure more to a viaduct, mainly because it has to support cement and earth and even Montreal’s notorious heavy snowfalls.

“The load is not that unusual,” he said. “It is unusual for an ice rink. Otherwise it’s almost like building a viaduct.”

Excavation for the $38 million LEED Gold project began last June and hockey is expected to be played by mid-November. The site is in very urban Westmount Park’s southwest corner where the old rink used to be.

Excavation finished in late November. The foundation and concrete slab installed, retaining walls with three inch plastic membranes to repel water seepage to drains below were put in place. City officials then gathered Dec. 4 to watch as the first beams were set.

The I-shaped beams, cambered to 20 cm height in the middle to bend to accept the above ground weight, are 32 metres long, and 37 of them will be used to span both rinks.

Each beam is 1.5 metres deep and spaced just over two metres apart, assembled with three plates of strengthened steel, and weighing 16 tonnes.

The contractor was lucky not to find any bedrock during the dig. But one unexpected problem was contaminated soil, which is reportedly costing the city an extra $1 million although Westmount officials have not supplied a final figure.

The site used to be a former gulley with fill dumped from excavated lands in downtown Montreal, which contained hydrocarbons. Under Quebec law, soil is divided into three categories and this was earmarked C+ which requires off island remediation.

The rest of the soil is being shipped about two kilometres to the planned rebuild of the city’s mammoth Turcot expressway interchange, just below Westmount.

Natural light will partly shine into the rinks from an above ground pavilion where there will be a cafe. Adjacent will be the city’s new 25 metre eight lane swimming pool and three tennis courts.

Inside there will be 10 dressing rooms, more than 100 spectator seats, an “agora” or gathering place lighting a multipurpose room and functioning like a mezzanine overlooking the rinks.

Total floor area is 80,000 sq. ft. The project will end up adding one acre of green space to the park.

Trent said demolition of the old arena opened up the storied park in a new way. People in nearby apartments “all of a sudden now have this wonderful vista,” he said.

Trent was a little dismayed by the lack of media coverage for the December walk-around. He said only the English Montreal media turned out.

He said “this is something that Quebec has done unique in the world by a Quebec-based contractor called Pomerleau and we didn’t get one word in the French media and not one television shot — nothing.”

Nevertheless Trent said the arena could be a model for future rinks in high density areas.

“I think this is a great approach for arenas that are close to the downtown core where land is very limited,” he said.