Precise Building Strategy Lifts Army Hospital Project
In the fall of 2009, before construction had even begun, the U.S. Army Corps of Engineers' first design-build hospital project, sited in Fort Benning, Ga., had become a contracting nightmare.
The two losing bidders for the $333-million Martin Army Community Hospital (MACH)—a McCarthy/Hunt joint venture and a team of Harbert Construction and Brasfield & Gorrie—were filing lawsuits relating to the selection of Turner Construction Co. and Ellerbe Becket/RLF Architects. By February 2010, the Corps was ordering Turner Construction Co. and EB/RLF to halt work.
The complaint alleged a conflict of interest on the part of EB, relating to its acquisition by AECOM. The U. S. Government Accountability Office concurred and recommended that the Corps terminate Turner's contract, which it did in March 2010.
Turner and its designer appealed in federal court and won. By August 2010—nearly a year after first winning the contract—they were back in the saddle.
The contract suspension, termination and reinstatement added $15 million to the contract's cost. The price is now about $385 million, thanks to the legal battles and other owner-initiated changes, including some design-build contractor-led hospital equipment procurement.
The BIM Factor
Since then, MACH is looking decidedly better, at least to officials at the Corps. "We've got some lessons learned," says Robert 'Alan' Bugg, USACE's area engineer. "But this job has gone amazingly well."
The Corps' contract gave Turner and Ellerbe Becket/RLF 1,200 days to complete the project, which included the 745,000-sq-ft replacement hospital, two 1,000-space parking garages and the central utility plant, all located on a sloping, 50-acre greenfield site. There are three main buildings: a hospital with six stories above grade and two below and two clinic wings that are separated from the main building by a "grand concourse."
With the legal skirmishes behind them, the team has turned the project into a model of collaboration, say those involved. That's mostly due to Turner's intensive push to integrate all design disciplines and construction planning, including much prefabrication, into a master building information model (BIM), owned and stewarded by Turner as the contractual design-builder.
The conventional design-build contract enabled the unusually intense BIM-centric approach. Turner made the BIM commitment—which wasn't required by the Corps—when it first formed its team. "We made an early decision to use full-building 3D modeling as our primary design-development tool," says Martin Miller, Turner's project executive. That move enabled many others, he says.
On many projects, the ownership of the model is in dispute in terms of the transition from design to construction, says Paul Zugates, an EB/AECOM senior vice president. On this job, which is the EB/AECOM health care team's first experience with the master BIM approach, the Turner ownership of the model was clear from the start, he says.
The Turner-stewarded master BIM strategy has been effective, say team members. It has turned at least one designer into a BIM enthusiast.
"At first, I was skeptical [and thought] we would lose control of the design," says Don Bailey, mechanical project manager and senior engineer with TLC Engineering for Architecture, the mechanical engineer of record. But MACH is "totally different from most projects" Bailey has done—in a good way. He says the number of requests for information and change orders as a result of design errors or omissions is lower than on any of his other projects.
After Delay, a Fast Track
Construction began in April 2011. Target contract completion is set for next May, with a "patient-ready" date of Nov. 17, 2014. The MACH has a structural steel frame with composite metal decking. It is clad in architectural precast concrete panels with a glass curtain wall. There are three green roofs—two to reduce stormwater runoff and glare, while the third serves as a meditation garden.
Turner required all designers and most of the project's design-build subcontractors to produce designs as BIMs. The contractor then integrated more than 200 individual models—built on 14 software platforms, from more than three dozen modelers—into a master model.
None of the design-build bidders were allowed to talk to hospital user groups prior to bidding. After winning the contract, the Turner-led team initiated a six-week design review for users. That resulted in several design modifications, such as changes to the layout of the emergency room, elimination of some physical examination spaces and the addition of more elevators—all of which had ripple effects on stairwell and electrical system placement, Miller says. In all, these and other changes added approximately $7 million to the value of the design-build contract.
A $16-million contract value increase was the result of Turner receiving orders from the Corps to procure some of the hospital's equipment, such as magnetic resonance imaging units and other radiology items.
The decision to have the contractor handle equipment procurement actually helped keep costs in check, says the Corps' Bugg. "That $16 million sounds like a huge modification, and it was, but that money was going to be spent anyway," he says. "We got a better deal from Turner than if the government had bought that separately."
Once these changes were incorporated into the design, the final building model took shape. "It was after that point that the BIM started to be the focus of design," Zugates says.
Prefab, Safety Benefits
The project team used BIM-enabled animations to help plan every aspect of construction, including how to move dirt around the site—which had a grade drop of about 230 ft from front to back—as well as crane placement and lifting plans. "BIM really enabled the execution planning during design," Miller says.
Some ceiling plenums are packed with utilities, making access for installing the fire-resistant drywall partitions difficult in locations where there is 7 ft 11 in. of ductwork and piping in an 8-ft-wide corridor, says Miller. BIM aided in identifying those locations early so crews could install drywall prior to the commencement of the overhead rough-in work. These "priority walls" were then inspected early by the fire marshal.
The heating, ventilating and air-conditioning system's variable air volume boxes, complete with piping and controls, were prefabricated at a local fabrication shop by subcontractor Brown-MMC. Ductwork was fabricated in Houston by McCorvey Sheetmetal.
The result, says Miller, was that, for site installation, "All you had to do is connect the reheat water and the controls, and it was done." Minimum and maximum air-flow settings were preset as well.
Other subs also made use of offsite preassembly and prefabrication as much as possible, including for piping, ductwork and electrical units.
The project's curtain wall contractor, Physical Security LLC, also got into the act, preassembling the glass components into the frames off site.
BIM also enabled early installation of anchors on the buildings' metal decks prior to placement of rebar and concrete instead of afterward.
Because the master BIM—and all early models provided by others—was oriented to a set of coordinates, crews were able to use robotic surveying instruments to determine the exact points for placing anchors from the floor above for the overhead rough-ins.
"Instead of folks standing on ladders and drilling upside down with hammer drills through metal deck, they're walking on metal deck and drilling and dropping anchors at their feet," Miller says.
The BIM also included worker tie-off points, which were attached to the structural steel at the fabricator.
"The model is what has enabled that level of prefabrication," says Miller.
"The quality is phenomenal," says Bugg, who adds that he has never heard a jackhammer on site. "Everybody who [visits] from the Corps and the government is impressed."
The factory fabrication environment has led to a "scary good" finish quality, Miller says. "The pieces have fit together almost miraculously."
Energy Efficiencies
To meet standards for federal buildings, the contract required a goal of attaining LEED-Silver certification through the U.S. Green Building Council's Leadership in Energy and Environmental Design green building rating program. Additionally, the new facility needed to be 30% more efficient than the ASHRAE 90.1 energy standard for buildings.
The design-builders opted to build the central utility plant with three centrifugal chillers, three hot water boilers and a steam system that Bailey says is "much smaller than you might expect" to serve the hospital's steam needs for sterilization and humidification.
To conserve water, condensate runoff from the HVAC system cooling coils is pumped to the cooling towers for makeup water.
The approach amounts to a significant water-conservation measure, says Bailey, who estimates that the amount of water saved from the collection of condensate will total as much as 3 million gallons a year, or nearly 25% of the cooling tower makeup water.
The biggest energy saver is the inclusion of variable-speed drives on all pumps and fans, says the designer. Bailey says that one of a hospital's biggest uses of energy comes from the requirement to create a system where air volume is constant.
In the past, building designers utilized constant-volume air systems to maintain positive or negative pressure relationships between spaces to control airborne infections, Bailey says.
On MACH, however, designers incorporated what Miller calls a "robust" building automation system that maintains the building's minimum air change requirements at all times. For this reason, the team was able to utilize variable air volume (VAV) systems to maintain minimum required airflows and thereby reduce the facility's future energy use.
Bailey estimates that when compared with a constant volume, multiple-zone reheat system, MACH's VAV system achieves a roughly 30 to 40% reduction in energy use.
"It achieves a tremendous amount of energy savings," Bailey says, "because of the reduction in reheat energy at the zone level, [which] minimizes the amount of simultaneous heating and cooling that normally would be going on in a constant-volume system."
So far, MACH is ahead of schedule for LEED Silver, the builders say. Miller says USGBC approved all 27 of the project's design-phase credits, and if the team is able to secure all 13 construction-phase LEED credits, the project should earn the higher LEED-Gold status.
To the builders, though, nearly all of the project's pluses can be attributed to the use of integrated BIM. "We could not have made the 1,200 days without it," Miller says.
