J.T. Magen resolves CoreSite’s new-build Chicago data center challenges
It took J.T. Magen two months of digging with massive drill bits to install the 219 caissons to support CoreSite Realty Corporation’s purpose-built Chicago data center. It was just the start of the construction hurdles to overcome on this complicated project. But with nationwide mission critical expertise, the J.T. Magen team was undaunted and is efficiently resolving all challenges.
CoreSite CH2 in Chicago’s South Loop business district is the first ever ground-up data center built in the city. The four-story, 196,000 sq. ft. colocation facility is specifically designed for the structural weight-bearing needs of large power, cooling, data and redundant systems. It’s located on a brownfield site and was designed by Corgan.
“All new buildings downtown need extensive deep foundations due to soft earth,” says Geoff Arend, executive vice president and head of the Chicago operation. “Structural supports in some cases go all the way down to bedrock, depending on soil conditions and the performance requirements of the building.”
Deep foundation work
At the CH2 construction site, the 219 holes dug for supporting caissons averaged 55 feet deep. The painstaking process required drill bits averaging four feet in diameter biting into the dirt, coming back up to spin out the dirt, and going back down for more until the soil tests verified it was hard enough to weight bear, explains Arend.
Casings were pushed down into the drilled holes to keep them from collapsing, rebar cages were inserted and then they were injected with concrete to establish the building footings. In all, 1,300 tons of rebar and 12,800 tons of concrete were used for the caissons and foundations.
The project could then go vertical with grade beams and the steel structure. More than 1,950 tons of structural steel are specified for the build-out. Two-thirds of the property footprint is a metal structure; the last third is concrete podium.
Site restrictions affect logistics
Since the site is bounded by city streets and adjacent structures, there is no staging or laydown area for materials and supplies, Arend explains. Due to the site restrictions, an innovative, non-standard strategy for equipment delivery and assembly had to be developed.
Some construction materials are being picked by the crane directly from the truck and put into place. Large equipment is being fabricated and partially assembled off site, and then mounted on skids before coming to the jobsite for quickly setting into place, he adds.
Location impacts phasing
The site is in a congested urban area and there is a 24-hour UPS distribution facility across the street, so the project has to minimize impact on traffic and adjacent businesses, says Arend. This makes phasing and deliveries a challenge – J.T. Magen has to close roads for the crane lifts, get permits and do work by night as a result. The project requires close coordination with CDOT and other building department agencies.
To minimize street closures, J.T. Magen has sequenced the building process so the crane can sit on the lot and start from one corner working clockwise until the last portion when the crane will have to be on the street.
The challenge of getting the amount of power and other utilities needed for the data center requires engineering, specification and logistical work with Commonwealth Edison Company, as well as other utilities providers, according to Wael Skaik, J.T. Magen MEPS project manager. As a result, J.T. Magen is building a dedicated onsite vault for ComEd to their specifications. The building design load is 24 megawatts.
The general contractor is installing more than 1.4 million lbs. of equipment in the first phase of development. That includes generators, chillers, enclosures, cooling towers, electrical switch gear, UPS systems, redundant power infrastructure, and redundant cooling and mechanical systems, Skaik says. There is campus connection via redundant high-count dark fiber to CoreSite’s CH1 data center.
Considering the complex logistical, foundation and MEPS requirements for CoreSite CH2, the completion schedule is aggressive. “I love how complicated this project is,” says Skaik, “all the challenges make it interesting. We have to solve the problems, work out the solutions with the team, and get answers in the fastest, most efficient way.”
Photo: © McShane Fleming Studios