The deepest part of the 98-story Wanda Vista Tower extends more than 100 feet below the banks of the Chicago River. This is where a handful of the skyscraper’s support chambers, called caissons, are drilled into solid rock. Designed to secure the structure and withstand the wind, the massive underground columns are among the many elements that Chicago-based McHugh Construction and dozens of subcontractors will complete before Wanda rises from the ground.
“These caissons are enormous,” explains Joel Kuna, the VP in charge of transforming a set of blueprints into Chicago’s third-tallest building. “Ten-foot diameter tubes that have a bunch of teeth on the bottom. Inside, we put thousands of pounds of rebar and concrete.”
McHugh Construction VP Joel Kuna and Project Manager Chris Tapas
Kuna has been with McHugh for 30 years. He joined the company after graduating from Illinois State, where he spent his days off building homes for a carpenter contracting business that he had launched with a friend. He lists the company’s “family-friendly approach” among his reasons for sticking around.
McHugh Construction was founded in 1897 by James D. McHugh, an Irish bricklayer from Chicago’s South Side. Its current chairwoman, Patricia McHugh, is his great-granddaughter.
When the caisson chambers are completed, a crane with a hoisting capacity of “around 30,000 pounds” will lift the tubes into place. The operator will communicate with workers on the ground through a system of hand signals.
“They go with hand signals because you want to keep your hands free for safety and the radio frequencies open for emergencies and the initial call to the operator,” says Kuna. “There’s swing left, right, bring down, hold that load… All kinds.”
An Iron Worker from Chicago’s Local #1 will send the signals up to the crane. Like all the workers onsite, he or she will wear a specific color helmet — for Iron Workers, brown — to designate his or her specific trade. The color-coding system helps tighten the choreography of the large, busy construction site.
Workers prepare the crane for hoisting
“On an average day, we’re hauling dirt, pumping concrete, assembling a crane, taking cranes apart, setting rebar and removing extra sheeting,” says Kuna. “If someone needs to find an electrician or a pipefitter, they can just look at the helmets.”
The crane that lifts the caisson is one of four dedicated to the project, including two that will be assembled onsite and a “bottom crane” that, Kuna explains, will attach to Wanda’s structure and “push on giant jacks to lift itself up” as high as 1,300 feet.
“You know Marina City?” he asks. “McHugh built that back in the day. We were the first ones to do a self-climbing crane.”
Although Marina City was built before his time, Kuna’s résumé lists a number of notable structures. Many of them — including Amoco/BP gas stations, ABC News headquarters and Russia’s International Monetary Fund — are in Moscow, where he spent his first four years with McHugh as Director of Field Operations during the defunct Communistic motherland’s rush to capitalism in the ‘90s.
Since returning to Chicago, he has expanded his list of achievements to include the Mag Mile’s Waldorf Astoria and New Eastside’s Chandler and Lancaster — “the first building out there,” he boasts. His knowledge of the neighborhood’s terrain is as deep as Wanda’s caissons.
“We’ve done it enough out there where we know the routine,” he says. “We are building on the old Chicago slips, which used to be water on the lakefront. They took the docks out and filled them with debris from the Chicago Fire — urban backfill. The ground is decent below 17 feet.”
Pouring concrete into the mat slab
A German-manufactured BG 39 excavator mounted drill rig helped McHugh reach that depth. It looks like a gigantic yellow screw attached to a bulldozer, weighs 330,000 pounds and extends to a maximum length of 118 feet. Upon striking a layer of rock between 20 and 80 feet, it extracted several soil boring cores — cylindrical samples of the earth — that were sent to geotechnical specialists for strength testing.
“As you go into rock, there’s the weathered layer, which could be anywhere from a foot to five or six feet deep,” explains Kuna. “There could be cracks on it because years ago water was running through it or whatever. The cores will tell you when you hit solid rock.”
The results help McHugh determine the proper depth of the caissons, which are divided into four sections called stems — west, center, east and ballroom. The stems are held together by two large sections of concrete called mat slabs, which the company began pouring in the last week of January.
Besides keeping the structure perfectly straight, the caissons also help it deal with the city’s legendary winds. To compensate for the sway that they induce, Canadian engineering and scientific consulting firm RWDI conducted tests on a mini-Wanda before construction began.
The 98-story Wanda Vista Tower, designed by Chicago architecture firm Studio Gang
“They put it on a scale model of Chicago and turn it one degree at a time and simulate wind conditions and run a wind analysis,” Kuna says. “It’s fascinating to watch.”
Combining this level of technological research with basic construction principles is a daily part of Kuna’s job.
The disciplines often meet in a doublewide trailer underneath Lake Shore Drive at the furthest end of Lower Randolph St., about two blocks east of the construction site. The location is an office suite, meeting facility and miniature kitchen with what appears to be Chicago’s blackest coffee. Kuna refers to a large area in the middle as “the war room.”
“This is where all the magic happens,” he explains. “We have a live feed (to the construction site) and we do all of our coordination meetings and 3D modeling here.”
On a recent afternoon, an electrician, a pipefitter and a plumber met with a couple of AutoCAD designers to coordinate the building’s mechanicals — the ducts, pipes and wiring for the electricity, ventilation and water that will bring the structure to life. Virtually walking through a 3D model of the interior displayed on a large computer monitor, they configured Wanda’s “vital organs” within the inches behind the walls “to make sure that they’re not hitting each other,” Kuna explains.
“Architects and owners don’t want to give you tons of room and space for stuff that they don’t want to see,” he continues. “So we’ve established standards over the years — this thick of a wall to put this size pipe.”
Cutting rebar to be placed into the network of reinforcing metal in the the mat slab
Kuna’s appreciation for space planning stems from a mishap that reduced him to tears on his first construction project. “When I was five years old, my grandparents bought me a Lego set and I built a giant airplane,” he recalls. “It was so big, I couldn’t get it out of my bedroom.”
Finishing the walls that will cover portions of the mechanicals adds another challenge to the job. Most buildings are adorned with flat panels, but a handful of Wanda’s lobbies and at least one of its restaurants will feature multifaceted marble.
“It’s got returns on it,” Kuna says. “It’s got beveled angles.”
To determine the best way to proceed, a scaled-down mockup of the tiles hangs on a wall in the war room. “We’re playing around with samples,” Kuna continues. “We want to see installment on three different planes.”
When the building is ready for interior decoration, the number of onsite workers will have expanded from 50 to “around 800, probably in the spring or summer of 2018,” says Kuna.
Several of them will be chosen from a joint initiative between McHugh and Magellan Development to hire more minority tradespeople.
Although Wanda may have achieved her ultimate height of 1,186 feet by then, Kuna’s job will be far from over.
“Not too many guys are crazy enough to do this for a living,” he says. “I love it.”
— Daniel Patton, Staff Writer