Foundation Repair Case Studies: Darling Ingredients Storage Silo Helical Support System

Thursday, April 8th, 2021 by Kendra Dunnigan


Darling Ingredients serves the agri-food industry by creating sustainable food, feed and fuel ingredients for a growing population. They have over 200 processing plants on five continents.

At their Wahoo, NE facility, they planned to construct three silos, each 20 feet wide and 60 feet tall. There was a tight 3 feet of space between the silos. Each silo, when filled, would weigh 1.1 million pounds.

The site space constraints and operation of the silos made it necessary for them to be close to each other. The concern was that the weight of each silo would be more than what the soil would support. If they relied solely on the soil to support the silos, each silo would have to be located 18 feet apart and require a 13-foot-deep over-excavation and re-compaction to strengthen the fill soil. Neither of these options was feasible.

The Geotechnical exploration overview suggested an alternative to supporting the silos on shallow footings with ample space between them. Bearing the weight of the individual silos on deep foundations or some intermediate foundation systems such as helical piers was a possible option. At this site, helical piers or a similar intermediate foundation system should be advanced through the clays to a suitable depth below the upper level of clay.


Thrasher and its engineering teams were able to design and provide an intermediate foundation system that would support the 1.1 million-pound silos. The design allowed the silos to be driven 3 feet apart as designed and site conditions required. The intermediate foundation system consisted of 84 3.5-inch diameter helical piles - 28 per silo. Helical piles were advanced to an average depth of 20 feet. Each helical pile supported an average of 118,000 lbs. The helical piles were installed at 5 degree altered batter angles to space the helices far enough apart not to overstress the soil. The project took seven working days to complete.   

Because of the close proximity of the silo foundations, the batter angles needed to be well-thought-out and executed. Thrasher Commercial Production Manager Brent Foreman agreed. “It was an interesting puzzle to install the piers without major disruption of the soil. It is one of the most unique intermediate foundation designs that we’ve been a part of,” Foreman said. “And, one of the most interesting. For us, it was a clever execution of a well-engineered solution that the customer loved.”


The solution Thrasher offered was the most cost-effective and efficient intermediate foundation support system, allowing the client to stay within budget and stay on schedule.

“This project is an excellent example of the adaptiveness of helical piles. They don’t displace any soil; there’s no vibration during installation, and once installed, they can be immediately cast into concrete,” said Foreman

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