Illinois State Fair Manager Rebecca Clark said the retrofit for the state fairground’s coliseum came in two waves, with the first completed in 2019 after the state’s 2015-17 budget impasse was resolved, fixing the structural issues, adding large fans and implementing other repairs to reopen the building to events from spring to fall – with bipartisan donations from both the departing Gov. Rauner and the current Gov. J. B. Pritzker supplementing state funds.

Now sheet metal contractors like E.L. Pruitt are working on the second phase, meant to bring complete climate control to the old building to accommodate year-round events. With double wall spiral duct from Lindab A.C. Manufacturing at standard size lengths of 4, 6 and 10 feet, Sheet Metal Foreman Mitchell Noll said he was able work with the design of the oval building, which lacks many straight lines and right angles.

“It was actually a circle at first, now it's an oval. They split the building in half, and added to the middle of it. Now when they did that 100 years ago, it didn't all end up square,” Noll said. “The architect and engineer provided us with a working 3D model to go off of, which is where we started our layout from. But then we had to go back in and field verify everything. So it was a nice mixture of kind of the new school and the old school.”

The 3D model was accurate enough to order materials off of, but when it came to installation, Noll said he used a framing square, pencil and level to check all his angles and distance off the columns. This ensured all the angles would line up with the oval end of the building.

“There's nothing straight here,” added Logan King, E.L. Pruitt pipe fitting foreman. “Everything's different degrees and nothing’s straight, nothing's plumb. But with today's technology, it's actually more of a breeze than anything because you can pretty well computer base anything you want to.”

Without any right angles to work off of, King says it’s an informing challenge.

“I've learned something new every day on this job, trying to figure out how to make these curves,” King said.

As with all retrofits, E.L. Pruitt had to work with the design of the building, which was never built to accommodate ductwork. This made cooling the lower levels where the bathrooms are challenging. The 2,500 seat amphitheater has high enough ceilings to accommodate the spiral duct, but the lower level couldn’t accommodate ductwork coming off the new dedicated outdoor air system (DOAS) units at ceiling height.

“We actually had to run it through an existing tunnel, which required apprentices to crawl through the dirt. To get hangers up, we actually had to dig the dirt out to run our supplies down to mount below the sinks and laboratories in the bathroom,” Noll said, concluding they also added ducted fan coils throughout the lower level.

As of now, the building accommodates about three dozen events by using fans and open doors for ventilation.

“But once HVAC and Phase II is complete, it’s really a game changer,” Clark concluded. “It will allow us to open the door and use this facility in the winter months with the heating element.”

Watch a video about the Coliseum's retrofit.