McCoy likes the Overhead Roll and Fold™ boom design that allows the main section to be tilted back, allowing the operator to smoothly raise the boom with the climbing form.

Twin 146-foot tall silos are slipformed continuously with a core wall that joins them together.

The concrete is deposited from the placer onto the floor of the climbing form. Laborers push the concrete into the form to maintain the correct volume.

The 24-hour operation means rebar is continuously tied on as the forms rise.

More than 120 men rotate in two shifts over the six day period required to construct the silo.

Big Boom Pays Off for Pumper On Slipform Silos

The ethanol boom continues to fuel business for concrete pumpers with the equipment to handle the concrete placing challenges required on these inimitable projects. R.L McCoy, Inc. with offices in Columbia City, IN and Indianapolis has seen one grain silo project turn into four more with their superior service, reliable equipment and versatile long booms. The most recent silo project for One Earth Enery LLC, occurred in Gibson City, IL near Champagne. McCoy has pumped five of the identical silos at different ethanol plants throughout the Midwest for Hogenson Construction, headquartered in Fargo, ND. Hogenson specializes in turnkey ethanol plants from concept through engineering and construction.

The twin silos at Gibson City are each 78-feet in diameter and 146-feet tall. The silos are tied together by core walls. The structures are built over tunnels that contain conveyors to move the grain from storage to the distilling process. In two of the five projects that McCoy has worked on for Hogenson, the pumper placed the footings and foundation walls for the below grade portion. The awarding of those was influenced by the proximity of the projects to McCoy’s offices in Indiana. The pumpers all-Schwing fleet consists of boom pumps from 28 to 61 meters. On the foundation pours, the company used a combination of their 32 and 39-meter booms with the renowned four-section Roll and Fold design.

The expertise of McCoy’s crew and the requirement of a long boom came into play when the slipforming of the silos began. “We put together a silo pumping package after the first project for Hogenson based on six days of continuous pumping with a four man crew,” explained Gary Brown, director of concrete pumping for McCoy. The pumper’s performance on the first silo and a competitive package resulted in four more of the marathon pours that culminated in the Gibson City project.

“Boredom is a good thing on these slipform silos, “ commented Brown, a former ACPA Board member, “Because once you start the pour you don’t stop for six to six and a half days. You don’t want any hiccups.” Brown chose the company’s versatile Schwing KVM 55-meter with four-section Overhead Roll and Fold Boom and 2525H-6 pump kit. With a vertical reach of 178-feet the boom has the reach to stay above the formwork. “The Overhead Roll and Fold design is nice because the operator doesn’t have to A-frame it because the main section angles away from the pour,” Brown explained. He added that reducing free-fall of the mix is another benefit of this design.

The Generation 3 pumpkit with 98-inch stroke and 10-inch diameter pumping cylinders cycles at just two strokes per minute to keep up with the slow but steady progress of the slipform. “We average about 210 to 240 vertical inches of progress per 12-hour shift,” Brown stated, “The pump provides a nice steady flow with no boom movement.”

The typical scenario for the slipforming of these silos was repeated at the Gibson site. Hogenson’s crew of 120 men arrived on the site on Sunday, June 8th before the next day’s slipforming began. McCoy’s pump and two-man crew also arrived on Sunday for a pre-pour meeting. “We discuss general safety procedures that include an evacuation plan, “according to Jared Thomas, project manager for Hogenson. The general contractor has specialized slipforming crews that include finishers, iron workers and general laborers who vibrate and feed the climbing form.

Hogenson designed a mini-placer system that incorporates two rotating arms that distribute the concrete around the perimeters of the twin silos. The 55-Meter boomed up to a working platform located 10-feet above the climbing forms. The pump’s end hose connects to a pipe and through a Conform Diversion Y-Valve which feeds the two placers simultaneously. To further control the pace of filling the form, the concrete is actually deposited on the form’s plywood floor and then manually pushed into the void as needed. The placers average about one revolution per hour in their slow, steady progress to the top.

Brown has kept the same pumping crew on all five of the slipform projects, “You don’t want a high energy operator on these types of projects, “he noted, “We picked guys that are attentive and patient.” Brown also picked the 55-meter for all five of the slipform silos. With standard Vector controls, the operator maintains two-way communication with the pump through the remote box where he can monitor pumping pressure and adjust the strokes per minute.

The mix design varies based on the aggregate available in the area, but 4,000 psi strength was common for all five of the projects. The requirement of at least 6-bags of cement per yard and no fly ash reduces the friction on the constantly moving forms. Because the five projects were accomplished over a 10-month span, retarders and accelerators were added depending on outside temperature.

“We understood that keeping our crew comfortable would be important considering the length of time they were on the job, “Brown said, “So we built a camper on a bobcat trailer and towed it to each site. As the jobs kept multiplying, we added a heater, then air conditioning, we waterproofed it and supplied them with a grill to cook on.” Brown supervises the start of the job, but then three men – two operators and a mechanic – carry the load in twelve hour shifts until the silo is complete.

Without any glitches, the slipforming starts on a Monday morning and ends the following Saturday. On all five projects, only once was there an unplanned shutdown. “We had this hellacious weather, “according to Brown, “We had to lower the boom because of lightning.” Otherwise midway during the weeklong pour, the operator schedules a 15-minute break to chip out the accumulated concrete in the hopper. Part of the McCoy package to Hogenson was a back-up pump on every project but it was never used.

Fueling is handled on the fly by a contractor who supplies diesel to all of the equipment on-site including the crane that lifts the reinforcing steel and the lights that burn all night long. The 55-Meter used 290 gallons to pump 2552 yards. “It took just about as much diesel to drive over and back as it did to pump the silos. We were really impressed with the fuel efficiency of the Schwing pumping twenty-four seven,” Brown stated.

And Hogenson has been impressed with the efficiency of the McCoy team. Thomas summed up the five projects, “A lot rides on the pumping for these projects. With so much at stake, the McCoy staff is always professional, competitive and good to work with.”


Project: Ethanol Plant Silo, Gibson City, IL
Owner: One Earth Energy LLC, Gibson City, Illinois
General Contractor: Hogenson Construction, Fargo, ND
Pumping Contractor: R.L McCoy, Inc. , offices in Columbia City, IN and Indianapolis
Equipment: Schwing KVM 55 concrete pump