Built from the inside out

Target Field, the new Twins Stadium, is a 12-acre facility on an 8-acre site. Mortenson employed building information modeling to orchestrate the construction process.

By Clair Urbain

The new Minnesota Twins baseball stadium sits in the heart of downtown Minneapolis, where Mortenson Construction and 85 subcontractors are putting the finishing touches on the $522 million facility – on time and on budget.

Actually, shoehorned into the heart of downtown Minneapolis may be more accurate. Bounded by 5th and 7th Streets on each side and by I-394 and a railroad line on the others, designers cantilevered the plaza over these thoroughfares to accommodate crowds and better tie the facility into downtown, says Dan Pennington, senior project manager for Mortenson Construction.

The one millon sq.-ft. open-air facility seats 40,000 fans and features a natural turf field. When completed, it aims to meet Silver LEED certification requirements. Populous, the designer that also created Camden Yards and the Nationals Park baseball stadiums, has taken Target Field into the 21st century with a clean design and a Midwestern feel with its limestone façade.

Throughout the facility, more than 800 video monitors and fan warming stations will make watching the Twins comfortable and exciting. “The site lines from any seat are phenomenal,” says Pennington. “This facility was designed around making the fan experience as positive as possible.”

Most new stadiums leave the ceilings exposed in the concourse areas, but Target Field concourse ceilings are finished off with a direct-applied exterior finish system (DEFS) that makes the outdoors feel like the indoors.

The service area is equally impressive. In most stadiums, the service area isn’t connected totally around the field – at Target Field, it is, further improving the fan experience because employees have better flow and access throughout the building, away from public areas.

Tight space and timelines

The challenge of a tight building footprint was further compounded by hitting a critical date of June 15, 2009. By that date, every crane had to be off the infield so crews could finish installing the various layers of aggregate, underground field heating system, then finish-grade and install sod on the field so it could be well established this fall. It must be ready to go for the premiere exhibition game against the St. Louis Cardinals and the season opener in April, 2010. Up to six cranes occupied the inner bowl during construction, and construction was staged from right field clockwise to left field, with crews finishing all six levels of a section at the same time.

However, before steel erection and concrete construction could begin, 3,300 pilings, driven up to 150' deep, had to be installed to stabilize the site, which was once a riverbed. To orchestrate the construction process, Mortenson Construction used building information modeling (BIM) to incorporate three-dimensional design with time, the fourth dimension, to keep the site construction progressing like clockwork.

“Dave Mansell, our senior project superintendent, has been very involved with the project plan since day one. We are self-performing concrete, masonry and rough carpentry and are working with 85-plus subcontractors on other aspects of the project. We require our major subcontractors to have BIM capabilities as well so we can work together more effectively. “BIM is a great tool if it is used effectively. It has helped us avoid last-minute conflicts. We were able to head off problems early and we were able to fix issues before they occurred. It saves money – no refabrication, removal or repairs are needed after the fact. It also helped us understand where the job was and would be at any date, and it helped the owner make decisions in a timely manner so that construction wouldn’t be held up,” Pennington says

Safety first

The cranes worked around the area on what is now the warning track; the infield served as a lay-down area for building materials. The external pre-cast concrete panels, covered with a Mankato limestone veneer, were placed from inside the ballpark. “It required a lot of blind picks. We preplanned each pick, keeping safety as our No. 1 priority,” Pennington says.

“From a safety standpoint, we have a zero injury policy and our subcontractors are required to implement the same safety policy. In the two million man-hours so far on this job, we have had one lost-time accident, which was a broken leg, and that worker was back on the site as soon as possible following the injury. We have since gone fourteen months without a lost-time injury. We put a lot of emphasis on safety when we select subcontractors and we look very closely at their past safety performance,” Pennington says.

The workforce, reaching 850 at the height of the project, is extremely diverse. More than 25 percent of the workers are minority and 5 percent female, and many are from local workforce development programs.

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Leading up to LEED

The facility has been designed to qualify for a variety of LEED credits, and the owner aims to achieve a United States Green Building Council Leadership in Energy and Environmental Design (LEED) Silver rating, based on the following criteria:

Sustainable site - Site selection - Development density and community connectivity - Brownfield development - Alternative transportation with preferred accommodations for bicyclists and low-emitting and fuel-efficient vehicles - Site development for maximum open space – Storm water control - Minimizing heat island effect – roof and non-roof

Water efficiency - Energy and atmosphere - Enhanced refrigerant management - Construction waste management: more than 85 percent was recycled - Recycled content: More than 50 percent of the steel was made from recycled steel. - Construction IAQ management plan – during construction and before occupancy - Low-emitting materials – adhesives and coatings, paints and coatings, carpet systems - Thermal comfort – design and verification - Innovation in design – green housekeeping, visitor education - LEED accredited professional on staff Target Field will be the second baseball park to seek LEED certification; the Washington Nationals’ park was the first.

Picture gallery:

9-18-09 A little more than one month after the installation of the sod, the field looks ready for play. At this point about 85 percent of the construction is completed and crews are confident that the facility will be completed on time and on budget.

2-22-08 A total of 3,300 pilings were driven to support the new stadium that is shoehorned onto an 8-acre site in downtown Minneapolis.

3-16-08 Cranes begin constructing the stadium from the inside out. Four Manitowoc 222 and two tower cranes are coordinated to keep construction progressing.

8-26-08 Construction supplies are staged on the infield and the cranes continue to work from a path that will become the field’s warning track.

12-28-08 Cranes begin setting the canopy that also houses the lighting and speaker system in the stadium. Every pre-cast panel on the exterior was a blind pick from the infield.

3-21-09 The infield begins to clear as construction progresses.

6-14-09 with less than two months before the critical sod delivery date, a substantial portion of the field is cleared of construction equipment.

As part of the LEED certification process, the coatings and sealants must be low- or no-VOC-compliant. Here, the concrete sealant applied to the concourse cures.

The Target Field plaza features these bat-like sculptures that will perform a light show. The plaza extends the facility over thoroughfares for better crowd flow and ties the facility into downtown Minneapolis. The stadium design is more modern than other recent ballpark projects designed by Populous.

Aerial photos by Blue Sky Aerial Photography/Aaron & Tracy Meisch www.blueskyaerialphotography.printroom.com. Other photos by the author and Mortenson Constructio.

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