January 26, 2012

POTASH CORP.

One of two steel storage facilities built by Potash Corp. is believed to be the fourth largest building constructed in the world without internal supports. The combined roof area of both structures is more than one million square feet.

FEATURE | Steel

Big steel over small timeframe for Potash storage building in Rocanville, Saskatchewan

PETER KENTER

correspondent

It’s not often that a construction project is so gargantuan that you could conceivably see its progress from outer space. That may be the case with the two recently completed steel storage facilities built by Potash Corp. of Saskatchewan Inc. to store potash from its Rocanville mine. The work was part of a $2.8-billion mine expansion in Rocanville, located in southeast Saskatchewan near the Manitoba border. The combined roof area of the buildings: more than one million square feet.

Both buildings measure 132 feet tall at the peak. They cover a width of 317 feet across with the smaller at 1,000 feet long and the larger at 1,225 feet. The larger building is believed to be the world’s fourth largest building constructed without internal supports.

When asked by a reporter for the Saskatoon Star Phoenix whether either of the buildings were large enough to contain a football field, the mine’s general manager, Steve Fortney, quipped that it could contain every football field in the Canadian Football League.

The buildings are designed to hold 526,000 tonnes of potash, about five weeks worth of production. That translates into enough potash to fill almost 5,000 railcars, which would stretch for about 68 kilometres placed end to end. The milled potash needs to be protected from moisture to prevent it from re-solidifying. Two buildings are used to separate fine-milled potash from the more coarsely milled product.

The facilities were built from structural steel with Type 314 stainless steel roofing and cladding. All told, the buildings used more than 8,700 tonnes of steel, with materials sourced among several suppliers to deliver the large quantity of product required in a short time frame.

Structural engineering was provided by Ruby + Associates of Farmington Hills, Mich. The company also designed the conveying system for distributing the metal deck sections along the steeply pitched roof and designed fall-arrest systems for workers.

Structural steel was erected by Midwest of Canada of Leamington, Ont. using steel arch truss frames with clear spans of 310 feet. The roofing and cladding contract was completed by East Iowa Deck Support Inc. of Burr Ridge, Ill.

“We typically don’t use stainless steel for a job like this,” says East Iowa co-owner Greg Naso. “The corrosive nature of the potash made it the best choice for this project.”

Although more expensive than some roofing systems, the shiny stainless steel was also selected because of its longevity. Naso says the company installed the stainless steel in sheets measuring three feet wide by 25 feet long using standard stainless steel fasteners drilled and tapped into the structure.

“The roof was a 7/12 pitch so that made installation a little more challenging,” says Naso.

Work began in August 2010 and finished in the fall of 2011, with time off for inclement winter weather from December to March. It was the company’s first foray into Canada, but Naso says it wasn’t much of an adjustment. “We’re from the U.S. Midwest and we’re already used to very cold, tough weather,” he says. “December in Saskatchewan was actually pretty mild.”

The company brought in four of its own team and used a daily average of about 17 Canadian-sourced workers to complete the contract. “We were really happy with the local Saskatchewan roofers,” he says. “They were hard workers.”

Building construction was completed in October 2011.

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