Firm name: Cleary Zimmermann Engineers
Project building name and location: Brooke Army Medical Center Central Plant Renovations, Fort Sam Houston, Texas
Type of building and type of project: Central Plant, Renovation
Project completion date and project duration: November 2010
Engineering challenges and solutions:
The existing 4,800-ton water-cooled central plant is to be expanded and renovated to increase chilled water firm capacity to 6,000 tons with 1,500 tons of reserve capacity. Each of the five (5) existing 1,200-ton chillers are to be replaced with new 1,500 ton machines and the chilled temperature difference of the plant was increased from 10°F to 12°F (to utilize existing pipe infrastructure to save first costs). Primary and secondary pumps were replaced to compliment the new chillers.
The entire plant was modeled in 3-D to accurately coordinate the required work and ensure minimal outages, as the facility must remain operational during construction. The three (3) existing steam boilers were also replaced with new 600 hp units. In addition, the DDC controls system was completely replaced. In order to accelerate the schedule, the chillers and boilers were selected and bid prior to the completion of the design. As the production schedule for the chillers was expected to exceed 16 weeks, the effort will save valuable time in the phased change-out effort. As part of the Central Plant renovation, the steam boilers that serve the hospital for hydronic heating and domestic hot water were replaced.
In addition to the equipment replacement, the DDC controls were also upgraded. As the facility was in continuous operation during construction, careful coordination was required to phase the change outs and transfer to automatic controls from the existing system to the new version.