Andrew Mellon Building Renovation
1785 Massachusetts Avenue, N.W.
Washington, DC
General Contractor: Grunley Construction Company
Engineer: Affiliated Engineers, Inc.
Architect: Hartman/Cox Architects LLP
Contract Amount: $5,750,000
Start Date: 7/21/14
Completion Date: 8/19/16
Challenges
The Andrew Mellon Building is a National Historic Landmark located on Embassy Row one block off Dupont Circle in Washington, D.C. Completed in 1917, the building was originally an apartment house that was home to many distinguished personalities with perhaps the most significant being Andrew W. Mellon, who served as Secretary of the Treasury from 1921 to 1932. During World War II the building was partitioned and converted to offices after which it was home to the American Council on Education, The Brookings Institution and the National Trust for Historic Preservation. Today the Mellon Building is home to the American Enterprise Institute.
Shapiro & Duncan’s scope of work required installation of new mechanical and plumbing systems in the existing five-floor building plus a penthouse. Before our work could begin, however, a massive demolition and reconstruction effort (conducted under a separate contract by another contractor) had to be completed because existing floors were not structurally sound enough to support the new mechanical, electrical and plumbing systems. Roughly half of each floor had to be removed, while the historical terra cotta façade was propped up during the pouring of new concrete floors. In addition, two basement levels were added by supporting the structure with new foundations and then excavating beneath and pouring new slabs, columns and decks.
In addition to the risk of damage or disturbance to the historic interior finishes, Shapiro & Duncan’s project team was also challenged on this renovation project by unforeseen conditions and frequent inaccuracies discovered in dimensions and the building structure. These unexpected conditions, which came to light when old walls, floors and ceilings were opened up, required our team to be extremely nimble in dealing with resulting changes in project phasing.
Another challenge was the diversity of systems and components comprising the new HVAC system. Instead of putting in a basic hydronic mechanical system, our team had to plan, coordinate and install a combination of hydronic, refrigerant, radiant and glycol systems – even a rainwater harvesting system.
The complex mechanical system includes: 7 new VRV systems consisting of 113 fan coil units; 6 new air handlers; 2 cooling towers (1 new tower plus a refurbished existing tower); 2 new chillers; new rainwater use system that feeds the open condenser loop with rainwater when available; and 4 new boilers (2 of which are used in a glycol system for fin tube radiators, with the other 2 used for the hydronic heating system).
The plumbing system, meanwhile, includes: 1 new domestic water heater, 1 new domestic booster pump; 2 sump pumps and basins (1 for waste water and 1 for storm/ground water); and rough-in and connections of domestic water, waste water, and gas for 2 kitchens, 11 gang bathrooms and 5 single bathrooms.
Solution
To avoid conflicts and find the most efficient system routing through the existing building’s structure, as well as plan alternate routes when structural records were found to be inaccurate, 3D model coordination with other trades was absolutely essential.
Those coordination documents, prepared by Shapiro & Duncan’s Virtual Design Coordination (VDC) team on our computerized Building Information Modeling (BIM) system, guided prefabrication of mechanical rooms, main pipes, and overhead runouts by our 51,000-square-foot fabrication shop in Landover, Md. These assemblies were then sent to the site for installation. Not only is prefabbing cleaner and more efficient, but logistically the footprint of the site, along one of the busiest thoroughfares in downtown D.C., did not allow us to bring material to the job site for cutting and assembly while other trades were at work.
Coordinated drawings were also instrumental in planning out hanger locations. Since the terra cotta would not hold the weight of the new systems being installed, hangers had to be attached to structural steel, which increased the chances of conflicts with supports, piping, conduit, and ductwork used by other trades. Our 3D coordination models made it easy to locate system supports without many conflicts.
Once installation began, fire risk was reduced through use, where possible, of heatless Reflok, Victaulic and Propress fittings when joining the differing piping systems.
The final element of our solution was the top-notch field supervision by our personnel well-versed in planning and installation of large-scale VRV and Reflok systems, not to mention the mechanical rooms where the diverse components of the Mellon Building system were tied together.
Results
Without a doubt, Shapiro & Duncan’s leadership in coordination set this project up for success. By spending the time to coordinate the project in detail with other trades, and by bringing the right people with the right skill sets and experience onto the project, we were able to deal effectively with all difficulties on this project. These included not only general challenges inherent in restorations of historic structures, but also specific challenges posed by the scope of restorations required for this 90-year-old building.
The success of this project demonstrates that Shapiro & Duncan is capable of detailed coordination, fabrication, and installation of the most varied systems and materials – even in circumstances where conditions provide many variables. Clients can have confidence that when our teams encounter unexpected changes in architectural, mechanical and plumbing design, which in turn trigger alterations in project phasing, we have the skill and agility to plan and implement a high-quality mechanical and plumbing system installation.
