For more than a century, Chicago-based James McHugh Construction Co. has developed expertise building many of the skyscrapers that dot the Windy City skyline. McHugh is known as the builder of landmark, one-of-a-kind structures, and its success is attributed to the company's commitment to creative construction solutions and innovation.
That commitment certainly helps when constructing an unconventional structure such as the Aqua, an 82-story high-rise which includes hotel, condominium, apartment, office, parking, and retail space. McHugh is the general contractor for this project under construction in the city's new Lakeshore East area at the Chicago River and Lake Michigan.
Aqua's tower design distinguishes it as one of the most striking architectural designs in Chicago, and it's McHugh's job to bring this design to reality. “Aqua is one of our largest projects and it definitely has some complexities that some of the other projects don't have,” says Dave Alexander, McHugh senior vice president.
The tower's exterior features a rippling effect – the facade is glass with undulating balconies that change slightly from floor to floor – that architect Jeanne Gang of Chicago-based Studio/Gang/Architects says mirrors the striated limestone outcroppings and formations that can be seen throughout the Great Lakes. Aqua's design has received international attention for the “waves” of concrete that will compose the balconies.
Studio/Gang/Architects is the consulting architect (exterior) for Aqua, and Loewenberg Architects, Chicago, is the architect of record. “Studio/Gang and Loewenberg really thought outside the box and developed a unique structure,” says McHugh Senior Project Manager Randy Bullard. “Aqua is very interesting architecturally and also from a constructability standpoint.”
With 2.3 million square feet, Aqua will be the first downtown building to combine condominiums, apartments and a hotel. The project owner is Aqua at Lakeshore East/Magellan Development Group. McHugh has built eight high-rise structures for Magellan, with Aqua its fourth project atLakeshore East.
Aqua, which has been designed to meet LEED certification, will feature five levels of enclosed parking and three levels of retail, hotel and amenity space on an eight-story base. The tower will feature 18 floors of hotel space, 30 floors of apartments and 25 stories of condominiums.
Aqua will measure 874 feet in height and although it is listed as an 82-story structure, it actually will rise 88 stories from ground level, with six levels of parking below the raised street level of Upper Columbus Drive. The building's eight-story base – which will be topped by an 80,000-square-foot terrace with gardens, gazebos, pools, hot tubs, walking/running track, and fire pit – will offer approximately 140,000 square feet per floor, while typical tower floors will be approximately 16,000 square feet.
|The "waves" of the balconies that provide Aqua's rippling effect extend out as much as 12 feet from the glass curtainwall.|
The building's exterior is being composed with approximately 300,000 square feet of glass. “There are five different types of glass in the window system,” Bullard says.
Construction of Aqua began in February 2007, with final completion scheduled for 2010. Residents will begin occupying the lower floors in 2009.
McHugh is serving as general contractor, but is using its innovative “design-build lite” approach by providing design-build services for structure and MEP (mechanical, electrical, plumbing) work. “This process works well for us because we do so much self-perform work and we control our schedule,” explains Alexander. “There are virtually no disputes with the owner because so much of the project is within our total control.”
Aqua construction is steadily moving upward. During an early October visit by Construction Digest, the tower had risen to the 58th floor. “We're running ahead of schedule,” Alexander says.
McHugh is overseeing a workforce varying between 250 and 350,with crews typically working six days a week.
Reinforced Concrete Structure
The reinforced concrete structure is being built atop 305 drilled bell and rock caissons, ranging from 4 to 10 feet in diameter and reaching as far as 112 feet below grade. In drilling the caissons, the project team had to work around more than 1,100 linear feet of Chicago's underground freighttunnels.
“That work required a tremendous amount of cooperation between us and ComEd,” Bullard says.
McHugh is self-performing the concrete work, pouring approximately 100,000 cubic yards of concrete for the project – ranging from 5,000 to 12,000 psi – and 11,000 tons of reinforcing steel. A low heat mix was used for the 3,000-cubic-yard mat foundation, which was placed on July 18, 2007.
Aqua's floors are placed by pumping concrete – via a Putzmeister pump – to each level, and the cantilevered balconies are monolithic with the floor slabs. Balconies at all floor levels are made with 5,000-psi air-entrained concrete. “We are placing a floor every three days,” says Paul Treacy, McHugh concrete superintendent.
Each floorplate in Aqua has a different shape at every level, thus construction is unusually complicated. The “waves” of the balconies that provide Aqua's rippling effect extend out as much as 12 feet from the glass curtainwall. “Every single floor is unique, and there is no repetition whatsoever in the waves,” Alexander says.
According to Treacy, the typical floor thickness is 9 inches. However, the balcony thickness varies. “Each balcony begins to slope just 8 inches beyond the column line,” he points out. “So, the further a balcony comes out, the thinner the slab becomes. Every piece of that slab is a different thickness as it contours out from the building edge.”
McHugh custom-built the concrete forms for the balconies, which are cantilevered past the edge of the structure, and are set using a computerized surveying system. The balconies will be topped by approximately 40,000 lineal feet of railings, each one custom measured since no two will be alike.
Other members of McHugh's Aqua project team are Suzanne Browne, project manager; Melissa Tompkins, Bill Middendorf and Scott Clark, assistant project managers; Shawn Rinkus, Colby Egan, Les Fitzpatrick, and Bob Rowan, superintendents; Geoff Vrba and Domenica Jimenez (tenant upgrades), project coordinators; Ryan Keane, concrete project manager; Steve Krebsbach, assistant concrete project manager; Sam Sampson, concrete superintendent; Jeff Hall, steel superintendent; Virginia Kobart, Maria Drozd and Michelle Cacagno, safety managers; and Tom Kruszewski and Doug Brunius, project engineers.
Magnusson Klemencic Associates, Chicago, is structural engineer for the Aqua project, and Case Foundation, Roselle, IL, served as foundation contractor. Other key participants include Prairie Material Services Inc., concrete supplier; Ground Engineering Consultants Inc., geotechnical consultant; Advance Mechanical Systems Inc., mechanical contractor; Abbot Industries Inc., plumbing contractor; Gurtz Electrical Co., electrical contractor; McDaniel Fire Systems, fire protection systems; Schaaf Glass Co., curtainwall (podium and Swissotel); EFCO Corp., curtainwall (tower); Midwest Steel Sales Inc., structural steel; and Kole Construction, framing and drywall.