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FEATURE Consolidating Systems for a Greener Future: Trinity University s thermal utility upgrade Bradley A.

1869, is a private liberal arts college set on a 117-acre hillside campus overlooking downtown San Antonio, Texas.

aimed at reducing its environmental impact. These initiatives include the construction of new buildings to LEED (Leadership in Energy and Environmental Design) standards.

1 FEATURE Consolidating Systems for a Greener Future: Trinity University s thermal utility upgrade Bradley A. Pankow, PE, Principal Engineer and Project Manager, Stanley Consultants; and Jesse Cabrera, PE, Senior Mechanical Engineer and Project Manager, Stanley Consultants T rinity University, founded in 1869, is a private liberal arts college set on a 117-acre hillside campus overlooking downtown San Antonio, Texas. A signatory to the American College & University Presidents Climate Commitment, Trinity has instituted numerous initiatives, under the banner of its Red Bricks/Green Campus sustainability program, aimed at reducing its environmental impact. These initiatives include the construction of new buildings to LEED (Leadership in Energy and Environmental Design) standards. The newest of these is the $127 million Center for the Sciences and Innovation, which opened in December 2013 and is the largest development ever undertaken on campus. In 2010, the impending science center construction and the campus s aging thermal utility system prompted Trinity University to look at its thermal utility infrastructure. Trinity hired Stanley Consultants to provide a comprehensive utility master plan that was closely coordinated with proposed campus expansion and improvements. This plan included a study of the merits of consolidating the campus s existing thermal utility plants and distribution systems in light of the science center s construction on the property occupied by the main plant. The three campus utility plants Bell, East and Main plants each Courtesy Trinity University. Photo Robert Benson. Trinity University s 280,000-sq-ft Center for the Sciences and Innovation is the latest of several new campus buildings to be built to LEED guidelines. Construction of the new center was an impetus for upgrading campus thermal utility systems. contained multiple chillers and hot water boilers with associated pumps. This arrangement delivered excess redundant capacity for the heating and cooling loads on campus. The completed utility master plan provided Trinity with thermal utility generation options and distribution system alternatives. It recommended consolidating the heating hot water generation into the East Plant and the chilled-water generation into the Bell Plant. Ultimately selected as the preferred course of action, this consolidation coupled with distribution system upgrades have already resulted in significant energy savings for Trinity University. 25

ENGINEERING DESIGN Design for the project kicked off in fall 2010.

2 ENGINEERING DESIGN Design for the project kicked off in fall Stanley Consultants was selected to perform a comprehensive, multidisciplined engineering design of the utility plant consolidation that included the interconnection of the thermal utility loops into one distribution loop for chilled and heating hot water. The interconnection of the thermal utility distribution systems required hydraulic modeling of the entire campus distribution system to ensure adequate supply at each campus building. Consolidation also required an upgrade of the campus electrical distribution system. Twothirds of the campus electrical system was recabled to provide adequate capacity for the new chillers as well as to upgrade the campus for longterm sustainability. The natural gas line feeding the East Plant was similarly upgraded in size. An expedited design was critical, as the Main Plant needed to be off line and ready for demolition by January 2012 to make room for the new science center and to minimize disruption to the campus while students were present. In order to ensure that equipment would be available for installation during construction, equipment procurement packages were issued for the new chillers, cooling towers and heating hot water boilers. The preprocurement of equipment allowed the design team to prepare drawings for the installation of known equipment, reducing the time required for shop drawing review and eliminating the need for redesign of piping and electrical layouts. RVK Architects provided architectural services to the project, ensuring that the exteriors of the new East Plant addition, the renovated Bell Plant and the new cooling tower screen wall blended with existing campus architecture. Design drawings were completed for the East and Bell plants simultaneously to accommodate the phases required during construction. Having phased drawings in the construction 26 package provided clarity to contractors bidding on the project, which helped to reduce bid package review time and speed up the project award. The notice to proceed for design was given in September 2010, and 100 percent construction documents were completed in February Construction of both the chilled- and hot water plants commenced in April 2011, proceeding in seven phases to completion Jan. 5, BELL PLANT: CHILLED-WATER GENERATION The consolidation of the campus chilled-water generation systems into the Bell Plant included the installation of four new high-efficiency variablespeed 1,350-ton chillers and related cooling towers. This provided a total capacity of 5,400 tons at a delta T of 10 degrees F. The chilled-water pumping scheme consisted of direct primary design with variable-speed distribution pumps. The existing distribution systems were combined to provide a single variable-flow chilled-water loop served by the Bell Plant. The distribution pumps were equipped with variable-frequency drives to vary the chilled-water flow within the system to meet operating conditions. Construction phasing of the Bell Plant was critical to project execution, since chilled-water production needed to remain active throughout the process. Launched in April and May 2011, respectively, phases 1 and 2 consisted of preparing the existing Bell Plant for the new mechanical and electrical equipment. This included the excavation and expansion of the Bell Plant yard and construction of the retaining wall foundation. Next, underground electrical duct banks, equipment pads, unit switchgear, transformers and motor control centers were installed in phase 3. Additionally, the underground domestic water piping and headers for the chilled- and heating hot water systems were installed, as were the building and auxiliary heating hot water pumps once the existing boiler No. 2 in the Bell Plant was demolished. Begun in August 2011, phase 4 followed with the demolition of the existing boiler No. 1 and the remaining heating hot water system. Phase Four new high-efficiency variable-speed chillers like this one were purchased and installed as part of the Bell Plant redesign.

5 added chiller No. 1, including the balance of plant equipment necessary for operation. Later that fall, phase 6 demolished the existing chillers and electrical switchgear in the Bell Plant.

3 5 added chiller No. 1, including the balance of plant equipment necessary for operation. Later that fall, phase 6 demolished the existing chillers and electrical switchgear in the Bell Plant. New cooling towers and pumps were subsequently installed in the expanded yard. Ultimately, phase 7 added chillers Nos. 2, 3 and 4 and the balance of plant equipment for operation. EAST PLANT: HOT WATER GENERATION The consolidation of the hot water generation systems on campus into the East Plant entailed the installation of two new hot water boilers and the relocation of one hot water boiler from the Main Plant. Phasing of the East Plant construction was critical to project execution since heating hot water production needed to remain uninterrupted. Phase 1, launched in spring 2011 concurrently with the chilledwater plant project, consisted of the construction of a new larger building encompassing the existing East Plant. A new gas line and metering station were completed to supply Hot and chilled-water distribution piping was installed in an open-cut trench in King Street to connect buildings to the Bell Plant. natural gas to the new boiler systems. Also included was installation of a temporary boiler at the Bell Plant with variable-frequency drive distribution pumps to provide interim heating hot water for the East Campus during demolition of the existing hot water systems at the Bell and East plants. Phase 2 followed with the installation of new distribution piping between the East and Bell plants, to be connected during the initial stages of phase 3. The new header piping included connections for the temporary boiler system. Two new heating hot water boilers were then installed and connected to the distribution system. Later in the summer, phase 4 included the removal of the temporary boiler system and final tie-in of all heating hot water piping within the East Plant. Phases 5 and 6 did not include any work at the East Plant. After the Upper Campus tie-ins were complete to the thermal distribution system, phase 7 allowed for the Main Plant to be shut down and for the third heating hot water boiler to be relocated into the East Plant. As completed, the expanded East Plant delivers N+1 redundant capacity via three 13,390-Mlb/hr heating hot water boilers utilizing a primarysecondary pumping system to provide heating hot water to campus. During the winter months, the heating hot water system supplies 180 F to campus with a return temperature of 160 F. During shoulder and summer months, the supply temperature is reduced to 160 F to conserve energy. THERMAL DISTRIBUTION SYSTEMS As previously described, Trinity had been served by three independent thermal utility plants Main, East and Bell. The distribution systems were not interconnected, and each utility plant provided hot or chilled-water service to a dedicated set of buildings on its respective distribution system. Existing piping materials in the distribution systems included PVC, steel and Transite, some of which was insulated and jacketed in PVC. Thermal utility plant consolidation required that each distribution system be upgraded to include a main trunk line allowing for heating and cooling service supply throughout campus. The upgraded system was designed to accommodate future building expansion and to provide ease of connection to existing building branch piping. Flow modeling of the interconnected distribution system was completed to ensure flow requirements were met to each building and to determine plant pump head requirements. A major design and construction consideration for the project was a very short window for underground piping installation to minimize disruptions to the campus and the surrounding community. The design of the thermal distribution system started with a 3D laser scan survey of the planned piping routes. This allowed the design team to locate protected trees, light poles, sidewalks, retaining walls and buildings electronically. Using the 3D scan and modeling software, the design team was able to determine piping alignments that minimized surface damage and the need for tree restoration. After routings were selected, underground storm and sanitary sewers and potable water piping systems were studied from campus maps and site surveys as necessary. The resulting main trunk routing minimized surface restoration and installation time. The thermal energy distribution systems were designed with external insulation to conserve energy and minimize lifecycle costs. Carrier pipe materials (carbon steel, polyethylene, PVC and ductile iron) were evaluated based on life expectancy, installation time, durability and the need for thermal expansion compensation. Ductile iron pipe was selected as the most beneficial across the evaluation criteria. Additionally, ductile iron was chosen since it could be used for both chilled and heating hot water and required the least amount of installation labor for both systems com- 27

4 bined. Restrained joint connections were selected to eliminate the need for thrust blocks at directional changes and to allow for multiple installation options. Also, restrained joints installed with the spigot end pulled back against the retaining ring (fig. 1) allowed for a design free of expansion loops on the heating hot Figure 1. Restraining Ring. Restrained joint pipe allows for pullback against restraining ring to provide for pipe expansion. Restraining Ring Source: Stanley Consultants and American Cast Iron Pipe Co. water system, further reducing the system cost. Additional design considerations included future distribution system isolation and interim thermal utility supply to campus while the Bell and East Plant modifications were under construction. Historically, the Main Plant served the Upper Campus buildings with thermal utilities. Logistics dictated that the Main Plant remain in service as long as possible to keep the buildings conditioned. The Lower and East Campus thermal utilities were addressed early in construction by installing the main trunk piping between the East and Bell plants. Once the main trunk piping was installed, thermal utilities were supplied from the two plants. Thermal utility tie-ins to buildings were made during late summer and early fall Upper Campus installation was completed after the Lower Campus piping was brought on line. Isolation valves between the Upper and Lower campuses allowed the installation phasing to be completed. The transition to the new piping mains on Upper Campus was completed during the break between fall and spring semesters. The main trunk piping was filled, flushed, rinsed and energized with a one-day outage allowed at each building to make the connection to the new main. The thermal distribution systems each include a dirt/air/water separator to keep the piping systems free of sediment accumulation. Once thermal utilities were supplied to the buildings on the Upper Campus, the Main Plant was taken off line. OUTSTANDING RESULTS Although the project was incredibly complex, installation contractor Harvey-Cleary Builders and Stanley Consultants successfully completed the design and construction within a tight time frame with minimal interference to the campus activities. According to John W. Greene, Trinity University s director of campus planning and sustainability, the results System Snapshot: Trinity University Startup Year Number of Buildings Served Total Square Footage Served Plant Capacity Number of Boilers/Chillers Fuel Types Distribution Network Length Distribution Piping Type Piping Diameter Range System Pressure System Temperatures System Water Volume Hot Water System million sq ft East Plant: 40,170 Mlb/hr 3 boilers Natural gas 6,600 ft piping Restrained-joint ductile iron with urethane foam insulation and HDPE jacket 4 to 14 inches 55 psig 180 F supply/160 F return (winter) 160 F supply/140 F return (shoulder and summer months) 82,300 gal Chilled-Water System million sq ft Bell Plant: 5,400 tons 4 chillers Electric 6,600 ft piping Cement-lined, restrained-joint ductile iron with urethane foam insulation and HDPE jacket 4 to 20 inches 60 psig 42 F supply/52 F return 125,600 gal Source: Stanley Consultants. 28

have been outstanding. He explains: The project has allowed Trinity to move forward with the construction of an equally outstanding Center for the Sciences and Innovation.

Greene adds that the campuswide electrical consumption has been reduced by around 10 percent and has not been this low since more than 10 years ago when the university had less square footage to air

With their inherent efficiencies and the energy savings they make possible, Trinity University s upgraded thermal utility systems are now more than ever prepared to help the institution achieve its

5 have been outstanding. He explains: The project has allowed Trinity to move forward with the construction of an equally outstanding Center for the Sciences and Innovation. The systems are working flawlessly. Greene adds that the campuswide electrical consumption has been reduced by around 10 percent and has not been this low since more than 10 years ago when the university had less square footage to air condition. With their inherent efficiencies and the energy savings they make possible, Trinity University s upgraded thermal utility systems are now more than ever prepared to help the institution achieve its goal of making tomorrow greener than today. Bradley A. Pankow, PE, is principal mechanical engineer and project manager for Stanley Consultants, focusing on educational and institutional steam, hot water and chilled-water generation and distribution systems. He was formerly factory manager and operations manager with H.J. Heinz, lead mechanical engineer for Raytheon Engineers and Constructors, and engineering manager for Rovanco Piping Systems Inc. Pankow holds Bachelor of Science in Mechanical Engineering and Master of Science in Engineering degrees from the University of Wisconsin-Platteville. He can be contacted at pankowbradley@stanleygroup.com. Jesse Cabrera, PE, senior mechanical engineer and project manager for Stanley Consultants, is experienced in large central heating and chilledwater facilities and distribution systems, and electric generating and combined-cycle plants. Previously, he was a project engineer for El Paso Electric Co. and Houston Lighting & Power Co. Cabrera earned a Bachelor of Science in Mechanical Engineering degree from The University of Texas at Austin and a Master of Business Administration degree from Texas State UniversitySan Marcos. He may be reached at cabrerajesse@stanleygroup.com. INSTALLATION COSTS REDUCED WITH VALUE ENGINEERING Applying value engineering in the thermal utility project, Trinity University, Stanley Consultants and installation contractor Harvey-Cleary Builders reduced project costs and preserved the construction schedule, while minimizing student and campus interruptions. Initial project bids had come in on the project with unfavorable results due to the compressed installation schedule, area subsurface rock, underground utilities and surface restoration costs. Working with the installation contractor and the university, the engineering team reviewed installation techniques that would bring down installation costs. These techniques required vetting of the piping material and the manufacturer s installation instructions against the system design and the proposed directional boring installation. Directional boring allowed the contractor to install the piping below existing underground utilities, reducing utility interruptions and relocations and subsequently reducing the amount of surface damage and restoration to be completed. Harvey-Cleary Builders enlisted an underground piping subcontractor experienced in installing direct-buried systems to handle this job. The use of restrained joint piping, mechanical joint fittings and valves, and transition couplings allowed the installation to be completed on time. Building connections from the main trunk piping were made on a building-by-building basis. Valve boxes placed at each branch connection allowed for building isolation in the event of future underground piping issues and for switching between chilled- and heating hot water service for those buildings not served by a four-pipe system. The valve switching areas for two-pipe systems at three buildings were designed and installed such that a future switch to a four-pipe system could be completed with relative ease. Directional boring, including under existing utilities, reduced surface restoration and minimized utility reroutes and conflicts. Shown here is the valve and directional-bore receiving pit on Upper Campus. 29

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