When Claudio Mion, general manager at Utility Structures Inc. (USI), says his latest plant upgrade went through the roof, he really means it. The Ottawa, Ontario-based precaster started the year with a new, custom designed 7,700-cubic-foot capacity aggregate storage bin that was installed in a rather unconventional way.
The producer stores aggregates 75 feet high in a tower — the best location at the 70,000 square-foot plant, considering its limited yard space and the need to keep materials dry and warm through harsh Canadian winters. This meant the 55,000-pound bin would have to be disassembled and removed, and a new 75,000-pound unit installed, at roughly the height of a seven-story building.
Custom batch plant designer and manufacturer, BMH Systems, proposed a unique approach: Go in through the roof.
Before cutting into the plant’s roof, BMH engineers designed a bracing system. They built a rigid steel platform around the edge of the hole that served as reinforcement, as well as a work platform.
“The plan was to remove the old bin in several sections because of its weight,” says Matteo Falcucci, operations manager for USI. “But after they took off the top section, they couldn’t take the rest apart because it was too corroded. It would have fallen apart.”
Instead, the bin was removed in only two pieces — the heavier section weighing 35,000 pounds — with a 385-ton crane. USI was responsible for preparing the site, including relocating the chemical bins and adding a new foundation for extra support beams to accommodate the new bin’s weight.
The installation was scheduled to take six weeks but was completed in four. USI has been at full capacity ever since. “After two months up and running with the new bin, we are still doing our best to keep up with customers’ orders,” says Mion.
But before taking these seemingly drastic measures, Mion and Falcucci went through a painstaking planning process. They offer words of advice for producers considering a similar project.
Weigh the options
Mion and Falcucci began planning to upgrade the 25-year-old aggregate bin when rust and corrosion threatened to affect the quality of USI’s products: mainly precast concrete light poles and utility and traffic-related products. Although they had done patchwork repairs on rusted areas, contamination from the bin was causing aggregate colors to come out improperly.
They considered a full repair to fix and recoat the entire bin. However, they were unable to find a contractor to accept the logistical challenge of emptying and refilling each bin compartment, and completing extensive repairs without disrupting operations.
Relocating the bin outside was not an option. Due to limited yard space, the aggregates would have to be stored far from the plant, which would mean installing a cumbersome and costly conveyor system.
Ultimately, they decided a new bin was the best solution.
Continuous operation was a priority. “We didn’t want to be stuck with a problem that would cause us to be shut down,” says Falcucci. Faced with an emergency situation, they might have been pressured to make a quick and potentially expensive decision for the sake of convenience.
Because they were prepared, Falcucci and Mion we were able to spend eight to 10 months planning for the new bin and soliciting multiple bids.
Understand your needs
With time to plan, the managers considered how the new aggregate bin could improve the plant’s efficiency. “We jotted down every idea, and asked as many questions as possible to improve on what we had and decide exactly what we wanted to build,” says Falcucci.
Capacity was an obvious place to start. They upgraded from an eight-compartment bin that held 330 tons to a bin with 12 compartments and a 385-ton capacity. A larger, faster bucket elevator delivers aggregates up to the bin at a rate of more than 75 tons per hour. Workers now spend a quarter of the time refilling aggregates compared to before; loading once a day rather than several times, without fear of running empty.
The new bin is configured with compartments ranging from 22 to 55 tons to optimize storage space for an average of 14 different kinds of aggregates and sand. It includes bins for small quantities of specialty aggregates that used to be stored in bags and added to the concrete by hand, in a tedious and expensive process.
The bin is also filled more accurately. Each compartment is covered and has a 30x30-inch opening for the conveyor. The design keeps aggregates separated, and eliminates waste caused by mixing and contamination of materials. If an aggregate is not frequently used, the opening can be completely covered.
USI also requested a design change to prevent corrosion. Inside the original bin, wet sand would settle on support channels and corrode them. They hope to avoid this with new sloped channels inside the new bin.
Other time-saving adjustments included adding plates to the bottom of each bin compartment to accommodate vibrators for individual aggregates. Each bin has a moisture probe opening, so probes can be moved as needed.
BMH also built a 38-ton capacity truck hopper with steam pipes to thaw and warm aggregates. Materials can sit in the hopper overnight to dry before being stored. USI worked with the equipment designer to design this system, instead of using heating pipes that release steam and unwanted moisture.
Safety features include covers and ladders inside the 25-foot bin compartments. Divot plates hold a special crane that holds workers who enter the bin, and can be mounted in several different spots for maximum reach. Catch trays under the conveyor belts keep the area clean of spilled aggregate, reducing the time workers spend around the belts. Clean-up has gone from once a week to every two months.
Rely on the experts
When reviewing the bids, Mion and Falcucci were impressed with BMH Systems’ technical expertise. The manufacturer had also designed and installed USI’s original aggregate bin. “When you’re dealing with somebody who has done the job before, it always seems to go a little more efficiently,” says Falcucci.
The bin’s removal and replacement was scheduled to take place during the Christmas holidays to minimize production downtime for USI. “We were impressed that they worked around our schedule,” recalls Mion.
The plant’s roof was repaired by Christmas Day, and the crew took a week off. When they returned, it was covered with a foot of snow.