The University of Massachusetts-Boston is in the midst of a major infrastructure project involving the development of a new utility corridor and roadway network for its 175-acre campus overlooking the Boston harbor. As part of the project, the school’s 40-year-old central utility plant also will be upgraded to a more energy-efficient primary and secondary pumping arrangement that serves the campus’ hot- and chilled-water utility loop.
The upgrade includes four 2,000-ton centrifugal chillers, three 800-HP boilers and one 400-HP boiler. The new hot water system has piping sizes up to 16 in. diameter and the chilled water system had diameters up to 30 in.
J.C. Cannistraro — a mechanical construction firm headquartered in Watertown, Mass. — provided HVAC fabrication and installation services for the project. Cannistraro has significantly invested in both building information modeling and prefabrication technologies to improve quality and efficiency.
Keeping it going
“The campus operates 24 hours a day all year long, which complicated the logistics of the project and the systems installations,” J.C. Cannistraro Project Manager Eric Beck explains. “To keep the campus running, we had to install temporary chillers and repipe the 400-HP boiler to serve the campus while the balance of the heating plant was upgraded.”
But the installations had to be done within a very small window. The installation of the system isolation valves for both the 400-HP boiler and 30-in. chilled water valves to isolate the campus/temporary chillers from the cup chiller piping upgrades had to be completed one weekend.
Furthermore, many services running through the plant were not affected by the update. These systems, including electrical, domestic water and fire protection, had to remain undisturbed while J.C. Cannistraro upgraded the HVAC systems.
“We had to fit a large amount of substantially-sized piping through this maze of existing services, without reliable as-built documentation for the plant,” Beck says.
In addition, the existing plant is below ground and features concrete construction, including the roof. “We were not permitted to attach hanger rods to the underside of the deck, only to the sides of the concrete beams that were supporting the deck,” explains Colin Detra, J.C. Cannistraro’s HVAC coordinator on this project. “This limited our pipe-hanger locations, requiring careful layout of the new piping systems.”
BIM and prefabrication
Using the Fabrication CADmep software to create 3D models of the existing plant, Beck and Cannistraro were able to design and coordinate the new application, including the hangers with existing connections and services.
“Given our limited time to install the temporary systems and the large number of systems we had to connect, BIM-enabled prefabrication was a perfect fit on this job,” Beck says.
Instead of traditional tape measures and plumb bobs, Cannistraro captured the existing conditions of the plant with laser scanning technology.
“I used the resulting point cloud as a reference to build a model of the existing plant, turning everything (from 3/4-in. conduits to 30-in. chilled water piping) into 3D objects,” Detra says.
Detra used the software’s 3D modeling environment to accurately design all the new systems. Using BIM allowed for the best coordination with the more than 50 connections and securing suitable locations for the hanger rods. In addition, this helped avoid interference with existing services.
Cannistraro also used the Fabrication CADmep software model to help virtually plan and coordinate phase-by-phase demolition and installation.
“For example, while we installed the hot water systems, we knew the chilled water piping would still be there,” Detra says. “So in our planning model, I displayed the new hot water and existing chilled water systems, as well as all unaffected services to verify the layout and minimize clashes during installation. Later on, I did the same thing to route the new chilled water system — toggling off the old chilled water system and toggling on the new hot water piping and unaffected services.”
Beck adds: “We use prefabrication whenever possible. It gives us a controlled environment and lets us perform months of work beforehand — helping to increase project quality and safety while minimizing project cost and schedule.”
Fabrication CADmep software played a critical role in that process and helped Cannistraro automatically produce intelligent shop drawings from the project model with the necessary level of detail for fabrication, including manufacturer-specific content and components.
“We generated several hundred spool sheets for this project,” Detra says. “With support from the software, it took half the time to create these sheets than it would by using 2D drafting software and the quality is better.”
In addition, the model has the intelligent data to drive automated welding machines, translating to almost 9,500 in. of X-ray-quality welding on this job.
The UMass-Boston project is currently in the late stages of completion. “For the temporary installations, we didn’t even need the whole weekend,” Detra says. “We had the systems installed and running within a day.”