Building Systems

The new facilities shown in the master plan reflect the university's twenty-five year development program, but the specific areas and uses of each building will be adjusted during the development of the building's program. The recommendations made in the mechanical, electrical and plumbing reports are conceptually based upon the twenty-five year development program. Designers of new facilities should re-evaluate these recommendations based upon the building program for the new facility and the actual as-built size and use of other buildings or facilities that have been constructed since this master plan was prepared. Appendix A contains a more detailed report of the mechanical, electrical and plumbing systems analysis and design.

Mechanical Systems

Buildings on the main campus receive chilled water and steam for heating and domestic hot water from the existing thermal plant, TEP-1, located in the northwest portion of the campus. TEP-1 has five chillers with a total capacity of 9500 tons and a firm capacity of 6500 tons. Chilled water and steam are distributed throughout the campus via a piping network located in utility tunnels, building crawl spaces, and utility trenches. There are a number of bottlenecks in the distribution system that prevent TEP-1 from providing additional chilled water and steam to the southern part of the campus even if capacity were to be added to the existing thermal plant.

Buildings to be built by 2009 will add approximately 6500 tons of chilled water load and about 51,000 pounds of steam (or the hot water equivalent) per hour of heating. The final build-out on the campus core will bring the total up to about 15,550 tons of cooling and 121,900 pounds of steam per hour.

Additional heating and cooling capacity will be added on the core campus in two ways. First, TEP-1 will be modified and renovated to increase heating capacity and to improve the reliability of its cooling and heating capacity. Second, a new thermal energy plant (TEP-2) will be constructed in the south portion of the campus to provide chilled water and heating hot water to buildings on the southern portion of campus.

The thermal needs of the new eastern portions of campus will be met by a new thermal energy plant, TEP-3. TEP-3 will be built using the same equipment types and sizes as TEP-2. The exception will be that TEP-3 will be equipped with steam boilers instead of hot water boilers due both to the large steam loads required by the research buildings and to the lack of another source of central steam. The food service buildings, housing and small stand-alone buildings will have independent heating and cooling systems.

The following three figures show proposed routings for the new chilled water, steam, and steam condensate lines which must be built both in existing and new portions of campus to serve additional loads. Additional information about the thermal utilities systems can be found in Appendix A.

Electrical Systems

The new facilities shown in the master plan reflect the university's development program, but the specific areas and uses of each building will be adjusted during the development of each building's program. The recommendations made in the electrical report are conceptually based upon this development program. Designers of new facilities should re-evaluate these recommendations based upon the building program for the new facility and the actual as-built size and use of other buildings or facilities that have been constructed since the completion of this document.

Sources of Electrical Power

Source 1:

The 1604 campus is provided electrical power from two 138 kV City Public Service (CPS) overhead transmission lines to the CPS substation located at the north end of the campus at Loop 1604. Within the CPS substation, power is transformed from 138 kV to 13.8 kV, metered, and delivered via two underground circuits to the UTSA main distribution switchgear located just east of the CPS substation.

Source 2:

A combination diesel/natural gas-fired engine-generator rated at 3500kW/4250 kVA, 4160Y/2400-volt, three-phase, four-wire is located at the Thermal Energy Plant. This generator is used primarily for providing electrical power to a 3000-ton, 3000 HP centrifugal chiller located at the Thermal Energy Plant. The generator is connected, however, in such a way as to permit back feeding of 480-volt systems (a 1000-ton chiller and Motor Control Center, MCC3) within the Thermal Energy Plant in the event of loss of normal utility service. Use of this generator greatly reduces the amount of electrical energy that UTSA would otherwise have to purchase from CPS. At the present time, it is not possible to serve electrical power from the generator to loads beyond the Thermal Energy Plant.

Existing Campus Distribution

Power is provided from the CPS substation to the UTSA campus via two 13.8kV, 800-amp underground circuits that terminate in the existing UTSA main distribution switchgear. The main bus of the switchgear is arranged in a main-tie-main fashion to allow maintenance of either of the two services to be undertaken without loss of power to the campus. With recent modifications to the CPS substation and to these two underground circuits, the capacity of the service to the UTSA campus has been increased to 20 MVA.

13.8-kV distribution throughout the 1604 Campus is accomplished by twelve distribution circuit breakers in the UTSA main distribution switchgear. These twelve breakers are connected in sets of two to each end of six loops serving the campus. All of these breakers are rated at 1200 amps/15kV with protective relays at various settings which can be easily field adjusted or modified to permit trip settings up to the rating of the cable being protected (240 amps). The 240-amp rating of the cable used allows each circuit breaker to deliver as much as 5736 kVA. However, to allow redundancy, only 5736 kVA is permitted per pair of breakers forming a loop. Each loop has a normally open switch located within the campus that divides the loop into two radial circuits. This main-tie-main arrangement on the distribution loops provides UTSA maintenance the same advantages as are available on the main bus. It also prevents a single fault from taking offline more than about half of the load on any given loop.

Existing Campus Load and Existing System Capacity

Since completion of the most recent campus master plan in 2001, the following loads have been added or are in the process of being added to the existing campus electrical distribution system: • Recreation Wellness Building (2002)
• Child Care Center (2002)
• Student Housing Phase I (2004)
• Student Housing Phase I(a) (2004)
• Dining Hall (2004)
• Facilities Services Building (2004)
• Main Building (2004)
• BSE 1 (2005)

The Campus Load Flow Study that was completed in August 2002 was recently updated in March 2004. This updated load flow study provides the estimated peak load of the existing UTSA distribution system and the estimated loop loading after the completion of all buildings listed above. Results of this updated load flow study show that the existing UTSA electrical distribution system will be maxed out after the addition of these loads and will require major modifications and upgrades to accommodate the anticipated growth of the campus in the near future and to the end of the planning period. See Appendix A for a more detailed look at the proposed system modifications.

New Campus Distribution

Two distribution system voltages are available in the existing CPS substation (13.8 kV and 35 kV). UTSA would prefer for the distribution system of the entire campus to remain at 13.8 kV. CPS personnel, however, would like to supply all power to the UTSA campus at 35 kV. The following is a list of advantages and disadvantages for each system:

13.8 kV Advantages:
• Symmetry of system, all equipment the same.
• Familiarity of UTSA operations personnel with 13.8 kV system.
• Due to the schedules of ongoing projects, this system can be modified in a timelier manner than going to a new 35 kV system.
• Allows loads to be transferred between loops as necessary to react to system outages.
• Can be implemented in phases to grow as the load on campus grows.

13.8 kV Disadvantages:
• Requires larger duct banks and more feeder loops to distribute the required amounts of power.
• Limitations on CPS transformer size will result in two metering points for the campus.
• Limitations on CPS transformer size will limit service capacity expansion to 60 MVA.

35 kV Advantages:
• Can utilize smaller duct banks and fewer feeder loops to distribute the required amounts of power.
• Could result in a single point metering for the campus.
• Service capacity expansion is not limited to 60 MVA.

35 kV Disadvantages:
• Requires larger footprint for installation of equipment.
• UTSA personnel are not familiar with the operation of a 35 kV system.
• Results in a mixed system on campus.
• UTSA would have to purchase and maintain two large substation type transformers to back feed old 13.8 kV system.
• Would make system on existing campus less flexible (i.e. cannot use 35 kV loops to back up 13.8 kV loops).

In developing the different options listed in this master plan update, both distribution system voltages have been considered. A total of four options have been developed.

Option 1:

Keep entire campus distribution system at 13.8 kV.

Option 2:

Continue to feed existing buildings and loads from the existing 13.8 kV system and feed all new buildings and loads from a new 35 kV system.

Option 2A:

Same as Option 2 but with both 35 kV feeds originating from the existing CPS, 35 kV service transformer.

Option 3:

Provide new 35 kV service to feed entire campus, back feed existing 13.8 kV distribution switchgear from new 35 kV system, continue to feed existing buildings and loads from the existing 13.8 kV switchgear and feed all new buildings and loads from a new 35 kV system.

Option 3A:

Same as Option 3 but with both 35 kV feeds originating from the existing CPS, 35 kV service transformer.

Option 4:

Replace and upgrade existing 13.8 kV switchgear and feed all existing and new buildings/loads within the existing campus from the 13.8 kV system and install a new 35 kV system to feed all new buildings/loads constructed on the east side of campus.

Option 4A:

Same as Option 4 but with both 35 kV feeds originating from the existing CPS 35 kV service transformer.

Although each option has advantages and disadvantages, the design team recommends Option 1 as the best short and long-term solution for electrical distribution. See Appendix A for a more detailed report of the electrical systems.

Plumbing Systems

Sources of Domestic Water

Domestic water is provided to the 1604 Campus by the San Antonio Water System (SAWS). There are SAWS mains located on Babcock Road, Loop 1604, Valero Way and UTSA Boulevard. SAWS is in the process of planning a main extension along UTSA Boulevard near Valero Way that will complete a service loop around the campus. When completed, this will provide a higher level of reliability and improved quality of service to the campus.

Campus Distribution

The distribution of domestic water is generally accomplished through a loop system. Numerous distribution branches of various sizes feed into clusters of buildings from the service mains and distribution loop.

Current Capacity

Based upon flow testing data of the existing system gathered by UTSA personnel, it has been determined that the domestic water supply system can be expected to deliver approximately 2480 GPM to building users at a delivery (residual) pressure of 42.0 PSIG.

Future Demand

In the past, the on-site system has been extended on a project need basis. This has resulted in the sizing of mains that meet the needs of a specific project or building expansion, but do not correspond to the overall campus master plan. It is strongly recommended that a master utility plan be developed for the campus and that future expansions honor the direction of the master plan.

Future water demand for each of the new buildings was determined by estimating the minimum number of plumbing fixtures required by the 2000 Universal Plumbing Code (UPC) for the estimated number of occupants. The UPC was also used to determine fixture unit loads assigned to fixtures. The number of occupants was estimated using the occupant density required by the 1997 Uniform Building Code to determine exiting requirements.

Unless modified, the future delivery (residual) pressure available in the campus water mains and loop will drop below 40.0 PSIG. Many buildings with plumbing fixtures located more than twenty feet above the ground will require some form of reinforcement of the domestic water pressure.

It is costly and inefficient to install individual booster pumps for each structure. Alternatives to providing domestic water pressure booster pumps at each building could be to either provide pressure booster pumps to the campus distribution system, or to provide an additional water service connection from a SAWS main. The most likely location for providing an additional water service connection is at the 14-inch branch main located adjacent to the proposed Performing Arts Center. This line could be extended south to intersect the SAWS main at UTSA Boulevard. A detailed analysis should be made to evaluate the impact to available system water pressure to determine feasibility and cost-benefits of this option versus addition of distribution system booster pumps.

New residence halls, academic buildings, and the new thermal energy plant may be served from a new distribution loop served from the SAWS main located on Valero Way between UTSA Boulevard and the Loop 1604 access road.

Fire Protection

Many of the existing facilities require the installation of a fire pump to ensure that adequate water pressure and flow is delivered to standpipes extending through the roof. It is anticipated that this approach will be applicable in the future.

An alternative approach would be to provide a centralized fire pump facility and distribution network to serve groups of new buildings, thereby eliminating redundant pumping capability and reducing the need for on-site generator capacity.

Natural Gas

The natural gas main owned by CPS that runs parallel to the Loop1604 access road can be tapped to extend branch piping to serve the new thermal energy plant. Final size and arrangement of distribution should be coordinated at the time of actual project design to best accommodate the layout of adjacent new academic buildings.

Sanitary Sewer

The existing sanitary sewer that connects Chisholm Hall and the center of the campus is inadequately sized for the new development to be built on the western side of the campus. The design team recommends building a new sewer system for these buildings that would connect to the city sewer mains on the western edge of the campus. It is also recommended that a new sewer should connect the natatorium and Special Events Center to city mains to the south. The new buildings in the central portion of the campus as well as the new eastern academic buildings will be connected to the existing sewer line located along the connector roadway. The eastern-most buildings should be serviced by new lines to be located along Valero Way.