Case Study
SuperSize Us: Two Illinois Cooperatives Add 1.3 Million-Bushel Sukup Steel Tanks With Sidedraws

Farmers Cooperative Association (FCA), a single-location coop in Varna, IL (309-463-2061), adds new storage almost every year.

In 2019, the coop added its first tank manufactured by Sukup Manufacturing Co., Sheffield, IA (641-892-4222), after its longtime construction partner, Grain Flo Inc., Heyworth, IL (800-842-4875), became a Sukup dealer.

General Manager Jay Junker Jr. says that at the time, the company wanted to go with a million-bushel-plus tank to accommodate the ever-increasing grain yields and volume in north central Illinois.

“The cost per bushel of a 135-foot-diameter tank is significantly lower than the 105-foot tanks we had been building,” Junker says.

There was one problem in going to a larger tank – FCA wanted the larger tank to have sidedraws, which would allow the coop to load trucks by gravity without turning on any grain handling equipment.

Sidedraws Unavailable on Bigger Steel Tanks

In 2019, sidedraws weren’t available in Sukup million-bushel-plus tanks, which had been offered since 2009.

The conventional thinking was that sidedraws would weaken the sidewalls too much, which already had to withstand the tremendous pressure exerted by more than a million bushels of grain.

Twenty miles to the south in Roanoke, IL, Roanoke Farmers Association (309-923-3841), faced a similar situation.

“We decided to add a big tank in May 2020 because we anticipated a lot of demand destruction due to COVID-19, and we needed a place to store excess corn,” says General Manager Terry Bline.

“That didn’t happen, but then demand from ethanol plants increased, and we also wanted to phase out some bolted steel tanks that date back to the 1960s.”

What sealed the deal on a 135-foot tank, the coop’s fifth from Sukup, was the availability starting in 2020 of sidedraw spouts in tanks of that size, he says.

As a result, both coops in 2020 engaged Grain Flo to construct nearly identical 1.3-million-bushel Sukup tanks, each with two sidedraw spouts 180 degrees apart. Both tanks were ready for the 2020 harvest.

Brent Hansen, Sukup commercial sales manager, says the manufacturer took a number of proprietary steps to strengthen its sidewalls to handle openings for sidedraws.

“Some responsibility remains with the tank owner,” he says, “Unloading operations need to be managed so tanks are emptied evenly around the circumference.”

Features of the Sukup million-bushel-plus tanks:

• Sidewall sheets and stiffeners are made from 70-ksi tensile-strength steel for extra strength. Heavy-duty corrugated plates attach sidewalls to rafters for an extra-strong connection.
• Patented splice plates eliminate the offset in bin sheets, which prevents gaps that would allow grain leakage.
• Patented double-ended stud bolts ensure a watertight seal between sidewalls and stiffeners.
• Triple- and quadruple-laminated sheets plus the aforementioned splice plates allow for faster erection than other tanks of similar size.
• Super Shield coating on galvanized steel sheets help maintain an attractive appearance over time.
• The extra-heavy-duty freespan roof has a load rating of 100,000 pounds, especially important in parts of the country that get heavy snow loads. It also is rated to stand up to 105-mph winds.
• A 16-foot flat-surface platform on 135-foot-diameter tanks allows for fill conveyor maintenance and provides a flat, safe place for workers to stand for inspections or maintenance.
• A knot-passing pulley system is standard on all structured roofs to help with safe bin entry, when necessary.

In addition to Grain Flo, other contractors on the project included Wieber Steel Construction L.L.C., for bin jacking; Wagenbach Concrete Construction, Inc. handling concrete work; and KDJ Sales & Service, Inc. for electrical work.

The new tanks at Roanoke and Varna have almost identical features:

• Both stand 135 feet in diameter, 97 feet tall at the eaves, and 137 feet tall at the peaks, each holding approximately 1.3 million bushels.
• The tanks sit atop 6-1/2-foot-tall concrete stemwalls.
• Both have flat concrete floors and outside stiffeners.
• Each tank has two sidedraw spouts 180 degrees apart.
• Each tank has a 34-cable grain temperature monitoring system installed by Canary Systems, a Safe-Grain system at Varna and an AGI CMC system at Roanoke.
• A set of six 75-hp Chicago Blower centrifugal fans provide 1/8.2 cfm per bushel of aeration through in-floor ducting, with the assistance of 18 powered roof exhausters.
• Tanks empty into GSI 10,000-bph above-ground drag conveyors.

Two major differences between the two projects:

• The Roanoke tank is filled by a GSI 30,000-bph enclosed belt conveyor, while the Varna tank’s GSI enclosed belt fill conveyor is rated at 40,000 bph.
• The tank at Roanoke is equipped with Sukup’s recently-introduced paddle sweep. The Varna tank has a GSI X-Series 16-inch sweep auger.

Ed Zdrojewski, editor

From the January/February 2021 GRAIN JOURNAL