Roof Revitalization kKeeps Inco Plant Open In Sudbury, Ontario
More than 50 workers employed on $7 million design/build contract
By Peter Kenter, Correspondent, Daily Commercial News and Construction Record

The Clarabelle Mill processing plant of Vale Inco separates nickel from copper concentrates to help increase the productivity of its Copper Cliff Smelter in Sudbury, Ont.

The company issued a request for bids on a combined roof demolition/replacement contract in 2007, with the understanding that the work wouldn’t interfere with processing plant operations.

Later than year, TESC Contracting Company Ltd. of Sudbury was awarded an approximately $7-million design/build contract.

The existing building was constructed 40 to 50 years ago with a roof constructed of haydite slabs, a lightweight aggregate material made of shale, clay or slate expanded through heat in a rotary kiln.

“Lightweight is a relative term,” says Pio Cerilli, vice president, Civil Contracting Division with TESC.

“They aren’t light at all. Each slab weighed about 300 pounds (136 kg), measured about two-feet (60 cm) by eight feet (2.4 metres), and they covered an area of about 120,000 square feet (11,150 square metres), which totals about 90 per cent of the roof of the operating plant. They’d seen the end of their service life and needed to be replaced.”

“Each one of the slabs was held down with welded clips attached to the main steel roof structure. The workers had to pop up the panels, remove the clips and take them to the edge of the roof where they were bundled and taken down by crane and removed to the facility’s tailings disposal area.”

TESC worked with the North Bay offices of J.L. Richards & Associates, an integrated architecture and engineering practice, to develop a plan to attack the roof revitalization project on two fronts while protecting plant operations and workers below.

The plant is divided into two areas of activity. On one side there are huge rod mills designed to grind ore into a uniform dust for separation. On the other side, flotation tank equipment separates the ground material into nickel and tailings.

“To protect the plant on the flotation side we built an engineered bulkhead over a secondary bridge crane used as a back-up at the plants,” says Cerilli.

“it was a movable platform that we used to travel across the plant in 20-foot (six-metre) increments, following along with the work we were completing on the roof.

“We’d remove the haydite panels and replace them with a steel roof deck that would be waterproofed and finished with an asphalt, tar and gravel roofing system.”

The bridge crane wasn’t available on the other side of the plant, so TESC constructed a platform made of aluminum beams and plywood decking that bridged the space between steel roof beams.

“The steel beams are roughly four feet (1.3 metres) deeps,” says Cerilli.

“We built a working platform that covered three or four bays at a time as we worked.”

The labour-intensive project saw about 50 workers on site, including TESC employees, OIRCA Member Contractor Douro Roofing’s workforce, and representatives from the engineering firm.

TEXC worked both sides of the plant simultaneously, beginning work in the spring of 2008 with completion estimated for December.

“The work flowed faster than we anticipated, and although the summer was rainy, some better weather conditions helped us out a bit toward the fall,” Cerilli says. “We completed the work in October, a few months ahead of schedule.

“Vale Inco workers were able to work through the entire operation without having to shut the plant down, and we completed the work without injuries, though we have to give credit to our contact Don Jobin and the work force at the plant, who made the process much easier.”

- reprinted from the Feb. 12, 2009 issue of Daily Commercial News and Construction Record.