CHICAGO — Shutting down a business temporarily for repairs can be hurtful to any company’s bottom line. Closing down one of the busiest train stations in the country can be catastrophic. Mortenson Construction of Minneapolis successfully tackled significant logistical and operational challenges while working on Chicago’s Union Station, including doing some of the overhaul in a public space, without interrupting passengers, the train traffic control center, several retail businesses and private and public events.

New Marley cooling towers being hoisted atop Union Station.

Photo credit:  Mortenson Construction

"Disruption avoidance planning was critical for the project as Union Station is not only an occupied public facility, but its Great Hall is also host to special events such as weddings, galas, and community gatherings. As work occurred within and surrounding the Great Hall, the team had to accommodate approximately seven major events over the course of the project, in some instances through temporary cooling measures," said Andy Frank, Mortenson Construction’s construction executive for the project.

Amtrak hired Mortenson to improve the Great Hall and revitalize the attached eight-story office building, which had been vacant since 2001. Amtrak made a smart investment to ensure its property was as attractive as any other prime real estate in downtown Chicago and planned to use this valuable asset to offset operating costs by bringing in additional revenue from office and more retail tenants and saving millions of dollars through energy efficiencies while improving the environment for train passengers and attendees of private events in Union Station’s Great Hall.

Amtrak is already realizing major gains. It has moved its Chicago office employees back into the building, partially occupying the second and third floors and saving more than $2 million in annual rent. By eliminating inefficient radiator heat, utility costs have dropped by more than $1 million so far in 2012, with an expected yearly savings of more than $2 million. In addition, air conditioning in the Great Hall has made it a year-round venue for events and these events are expected to bring in another $1 to $2 million annually.

To generate more revenue to put toward operating costs, Amtrak is working with Jones Lang LaSalle, the building’s property manager, to market the rest of the available Headhouse office space as well as 60,000-sq.ft. of upgraded retail space surrounding the Great Hall.

"What was previously unrentable space because of life-safety issues and inadequate ventilation systems has become prime real estate," said Ray Lang, president of the Amtrak-owned Chicago Union Station Co. and the railroad's chief of state government relations.

New Fulton model VTG 4000 gas fired boilers providing heating water to the HVAC systems.

Photo credit:  Mortenson Construction

As part of a $25 million infrastructure improvement project, Mortenson Construction upgraded or replaced the building's mechanical ($6 million), plumbing ($750,000), fire safety equipment installation ($600,000), including sprinklers and fire alarms, and electrical to help make the 87-year-old building compliant with city regulations and set the stage to market the upper floors for tenants.

The mechanical work was subcontracted to AMS Mechanical Systems Inc., Burr Ridge, Ill., and the plumbing was subcontracted to O'Sullivan Plumbing, Mokena, Ill. Together they worked on the installation of the plumbing, piping, heating and HVAC systems.

The HVAC consisted of Marley Cooling towers, York air handling units and chillers, Fulton Boilers and Taco Pumps. The plumbing and piping on the project consisted of all cast iron and copper piping. Metropolitan pumps also were used. The fire safety equipment consisted of Notifier alarms and the wet sprinkler system was furnished and installed by F.E. Moran.

Starting in April 2011 and completed in October of the same year, the primary portion of the work occurred in the sub-basement of the facility, which is inaccessible by vehicle and located two floors below the water level of the Chicago River. There were no built drawings for Mortenson to use, so the company relied on extensive use of 3D laser scanning and modeling.

"Building Information Modeling (BIM) was an incredibly powerful asset during both design and construction. Because built drawings did not exist, Mortenson scanned the existing structure and incorporated the scanned information to build a 3D model," said Frank.

 To solve the puzzle of how to remove and replace the massive chiller and boiler equipment, the team created a Gantry Crane access point. Originally seen as a temporary measure, but installed as permanent access point to the basement levels, a portion of the loading dock roadway (above the chiller room) was removed and a large-scale Gantry Crane was installed to transfer the equipment and materials from delivery trucks and lower it into the sub-basement. Despite the access, much of the equipment, including the chillers and air handling units, still required delivery in sections.

Throughout the project, extensive field investigation was necessary to evaluate and confirm the existing conditions. The engineer’s design of the system was completed to a schematic level, and later relied upon in-field investigation and laser scanning to document exact locations and tie-ins. It used these tools to determine the best way to disassemble and remove the old mechanical and electrical systems, then to carefully design, fabricate and assemble onsite the new systems.

"Without this technology, the extraction of existing equipment and installation of five industrial boilers and two 600-ton chillers would have added considerable cost and time," said Frank.

Whether it was closing off a busy Chicago street, coordination with the historical society or addressing the structural differences and MEP system found in a 1920s building, the project’s location in downtown Chicago and its historic significance played a major role in the project planning and execution. Installation of two cooling towers and a structural support platform on the roof of the building required the use of a hydraulic crane positioned and, in turn, the closure of the street for public safety. The street closure had to occur during traffic “off hours,” so the team’s work began at midnight on a Friday and was completed just 36 hours later, by noon on Sunday. Because the cooling towers were modifications to the appearance of the building, the team collaborated closely with the Chicago History Museum (Chicago Historical Society) to screen the towers, as well as match paint and architectural details on any interior areas of disturbance.