Missouri hospital rebuilds after tornado using ‘integrated’ methods for HVAC construction
Mercy initiated plans to build the new $335 million Mercy Hospital in Joplin, Mo., in just three years. The owner and its general contractor, McCarthy, made the decision early in the design phase to bring in the major mechanical, electrical and plumbing subcontractors in a design-assist role — aka the modified integrated project delivery construction method.
As part of the team, U.S. Engineering was hired to handle the mechanical and plumbing design, fabrication and installation of the entire project. Given the tight schedule, size and scope of the job, and the survey-accuracy positioning required for every component, U.S. Engineering knew it would have to draw all of its technology expertise to keep the project on track. They’ve stayed on schedule and much more. Since project go-ahead in December 2011, the company has established what it says is one of the industry’s most efficient, accurate and repeatable design-to-fabrication-to-installation workflows ever put in place on a hospital project.
Bigger and stronger
The new 875,000-square-foot Mercy Hospital Joplin, designed to withstand the next powerful tornado, will include beds for surgical, critical care, women’s/children’s services (labor, delivery, recovery and postpartum rooms), behavioral health and rehabilitation. The bottom three floors of the structure will include hospital space along with a 7-story patient tower and a 4-story clinic tower rising above the hospital space.
The facility also incorporates heavy-duty mechanical, plumbing and electrical systems. A new 30,000-square-foot central utility plant will house emergency equipment and generators located away from the hospital with a strengthened exterior. Utility service access to the plant from the hospital will be via a 450-foot underground tunnel.
The hospital mechanical and plumbing systems include the necessary components for fuel storage, air supply and return, chilled water, condenser water, HVAC and plumbing as well as piping for the tunnel between the hospital and the utility plant.
For example, the plant system includes three steam boilers and boiler feed pumps fed by a high pressure 12-inch steam main. The central plant’s chilled water system includes three 2,000-ton chillers and three chilled water pumps with 24-inch supply and return mains from the chillers to the tunnel and chilled water return main from pumps to chillers. The plant also includes three cooling towers and three condenser water pumps connected by a 30-inch underground main.
To bid on the project, the owner and the general contractor mandated that all subcontractors had to have 3-D coordination capabilities. Due to the timetable of the project, the goal was to use the detailed 3-D model, which would include all MEP elements, to issue construction documents and facilitate a speedier start to fabrication.
Jeff Kiblen, U.S. Engineering’s project manager of fabrication and 3-D coordination oversight for the mechanical and plumbing systems on the project, said the work was quick.
“We came on board in December 2011, and we were putting in deep underground by March 2012,” he said. “Most projects of this scope and scale would require six weeks to complete drawings, issue documents and finish detailing. Because of the modified IPD methodology, we had to be exponentially faster.”
The Mercy Hospital Joplin project broke ground in January 2012 — eight months after the tornado. Once the foundation and structural steel had been installed on the site and the first floor deck pour was complete, U.S. Engineering began installing the hangers and sleeves for the piping and sheet metal components that would be routed overhead.
“This was our biggest challenge on the project,” Kiblen said. “On any given day, we’d need to locate hundreds of points on a given floor, which spanned over 100,000 square feet. At the beginning of the project, we had three Trimble RTS robotic total stations to be used by our 6-8 member field team.”
Robotics to the rescue
The pace of the project design, fabrication and installation drove the need for more robotic total stations, and U.S. Engineering’s interest in the Trimble rental program. Through the program, the firm was able to rent two more identical robotic total stations.
For the hospital projects, the team used three Trimble RTS773 units connected to the Windows 7 Trimble field tablet and two Trimble RTS655 total stations connected to Nomad handheld units. Due to size of project and potential Wi-Fi issues on site, connectivity using the Trimble robotic total station unit’s integrated radio frequency communication capability ensured no signal loss.
“The military-grade radio has made a huge difference in connectivity and communication throughout the project,” Kiblen said.
Once design of the mechanical and plumbing systems was coordinated and approved, U.S. Engineering used Trimble Point Creator for CAD (computer-aided drafting) and Revit to create 2-D and 3-D field points within Revit.
“This was the first time that we had used TPC (Trimble Point Creator) to this magnitude,” Kiblen said. “One great advantage of the tool is the ability to break systems up into more manageable sizes. For instance, the mechanical systems might be broken up as third-floor patient tower exhaust, return and supply air.”
To the field
Once the team was ready to move into the field, the points were exported to a Trimble Field Link for MEP robotic total station to lay out the floor penetrations and hanger support embeds.
“Overall, it took us 2-3 weeks to complete each floor including setting units, triangulating and then positioning,” Kiblen said. “On average, the field layout person can routinely lay out between 40 to 50 points an hour in good conditions.”
U.S. Engineering has completed the design of the mechanical and plumbing systems and located in excess of 78,000 points for sleeves, embeds, floor penetrations, drains and hanger supports. The points located on the first and second floors of the hospital main building exceeded 38,000 points. The third floor, which is common to both towers, had roughly 10,000 points. The 6-story patient tower added another 22,000 points and the three-story clinic tower another 8,000 points.
U.S. Engineering has also used the Trimble Point Creator for CAD and Revit and Trimble Field Link for MEP connection to verify as-constructed conditions with the architectural floor plan.
In terms of accuracy, U.S. Engineering is also very satisfied.
“Any inaccuracy especially with sleeve layouts in walls for plumbing would have created significant fit problems,” Kiblen said. “We needed to be within 0.25-inch or 0.5-inch because of the density of ceiling spaces, and tight coordination with all the other systems. Thus far, we’ve realized incredible accuracy thanks to our 3-D model-to-field workflow.”
The building exterior was to be complete in November 2013 and the plant operational by this month. The main structure expected to open in early 2015.
This article and its images were supplied by Trimble.