Case study: Public safety meets resiliency goals

Mechanical, electrical and plumbing infrastructure needs to be evaluated during the design phase for added resiliency, based on the client’s requirements

By Cameron Brown August 27, 2020


Learning Objectives

  • Learn how one facility designed a resilient building to achieve its goals.
  • Understand the nuances of resiliency and redundancy in building systems.
  • Know how electrical or HVAC systems can be specified to meet the owner’s resiliency requirements.

For the San Antonio, Texas-based Quarry Run Regional Operations Center, the idea of building resiliency was well-defined. A tour of the operations center with Bexar Metro 911 Network’s former CEO William “Bill” Buchholtz doesn’t start with its bright and sunny administrative spaces or even at the high-tech, futuristic public safety answering point. Instead Buchholtz starts all his tours in his favorite space: the electrical room located deep inside its hardened, mission critical core.

The room, with its rows and rows of electrical conduit aligned in an intricate pattern of overlapping and parallel pipes, is the building’s beating heart. The mechanical room also gives a sense of the complex and thoroughly thought-out systems that make this building fully resilient and seamlessly operational in the event of any emergency.

The Quarry Run Regional Operations Center, which opened in July 2017, accommodates multiple agencies and can support different functions, and it primarily serves as the main PSAP for the Bexar County Sheriff. In addition, it provides backup communications for the San Antonio Police Department communications unit, San Antonio Fire communications division and all communications units for two additional counties. If all those units’ communications fail at once, this facility can take over.

To achieve resiliency goals, this facility was designed to withstand severe weather events and backup four different public safety call centers across three counties. The client knew what the responses were to those events and how the building needed to operate before, during and after each event. The client knew that the communities and constituents depend on the services and consistent response times. To achieve this, the building and its systems had to meet the highest standards of resiliency possible.

In particular, the mechanical, electrical and plumbing systems design had to overcome multiple types of failures. Incorporating redundant components and pathways in the electrical distribution system ensures that power is available to the facility at all times. Likewise, redundant components and pathways in the heating, ventilation and air conditioning system ensures that all communication equipment stays within operating temperature.

Defining resiliency

It is important to distinguish between resiliency and redundancy. Resiliency refers to the building as a whole. Redundancy refers each individual system that makes up that building. For the building to be resilient and respond to the faults that occur, the individual redundant systems must work together. These systems include but are not limited to the mechanical cooling, mechanical controls, electrical distribution, lighting controls and telecommunication distribution. Adding redundant components, capacity and pathways for each system helps create a resilient building.

Making a resilient building adds cost to construction and complexity to the operations. It is important to make sure that designers and owners are aligned on this point. The goals of the project need to be clearly defined during the initial phase of the project to make sure the owner gets the building it wants.

Here are some questions to help guide the owners through defining the level of resiliency required for the building:

What type of failures or events are you planning for? It could be a natural disaster or a failure in one of the building’s systems. Each event will need a separate response. Do you need to plan for hurricane winds? Are you in the 100-year flood plain? Or 500-year flood plain? Are you in an earthquake zone? Will you seismically rate the equipment and/or the pathways? It’s important to talk about the faults you want to plan for, what type of responses are appropriate and whether to plan for multiple simultaneous failures of separate systems. Responses to these questions will significantly change the design.

How long do you plan to be without resources? Whether it is spare parts, fuel or water, what is the plan to overcome the fault? How many spare parts will you store and where will you store them? How much fuel do you need on-site? How difficult is it to get fuel? Where will the fuel truck park to refuel? Is a temporary generator connection a better option than on-site generation? If you are using chilled water for cooling, will you store water in case of a water disruption? Do you need to have pumped refrigerant units for critical spaces instead of water storage? These questions help owners think through how to respond during the event.

Will the building be operational during the event? Different events pose different real-time operational challenges. For example, if the building needs to be operational during a hurricane, that will change what equipment, if any, can be placed outside. That, in turn, raises the issue of whether to incorporate hurricane-rated generator enclosures or build generators into the building. What if only part of the building needs to survive? How does that change the electrical distribution and HVAC systems?

Will the building be staffed 24/7? That decision defines the type of responses the system can have and how much automation is required to respond effectively. If the building will be staffed during normal business hours only, then more automation may be necessary. If an operator is always present to help triage the situation, that reduces the demand for automation can be reduced. Finding a balance is important.

Collaboration between the owners and engineers in the planning phases is essential to designing building systems that meet the clients’ resiliency goals. Walking the building owners through different scenarios will help them visualize how they want the building to function. Engineers can then explain the design and cost implications of the owners’ desired functions.

Routes to resiliency

Figuring out where to add redundancy and how much to add is the challenging part of designing a resilient facility. Both the electrical and mechanical systems should be evaluated for single points of failure. Those single points of failure need to be analyzed against the design criteria and the other systems single points of failure. This ensures the building systems work as one. The systems also need to be evaluated for maintenance opportunities. What equipment needs to be maintained, and how often? How does removing one piece of equipment affect that system or building operation?

Take electrical distribution, for example. Once the building owners and engineers define what parts of the building cannot lose power, there are multiple methods to achieve this objective. The electrical distribution system should provide multiple pathways (A and B systems) to those loads. How the engineer creates separate systems is not as important as maintaining the separation all the way to the load.

One approach is to start at the utility entrance level with two different electric utility feeders that terminate into separate switchgear. Another method is to split into two feed before it enters the building. Another idea is to use a single utility feed and center tap the switchgear. Then use either side of the switchgear to create the A and B sides.

What happens when the utility power is lost? On-site generation is a must for those situations. One generator could be used to back up both systems. Individual generators for each system will make the electrical system more reliable, but cost and space restrictions need to be considered.

Spare breakers can satisfy multiple goals simultaneously. The client can provide spare parts for in-use breakers and can allow for expansion or a place for temporary loads during maintenance or construction activities. Spare breakers add a great amount of flexibility to the system that can become invaluable in the future.

Power quality can also be a concern. Are any of the loads sensitive to voltage sags or surges? Does the utility have a history of unstable frequency? Adding uninterruptible power supplies or voltage regulators into the electrical system makes for more stable electrical supply.

Based on the classification of the facility, the electrical system may fall under NFPA 70: National Electrical Code Article 708 critical operations power systems. This is a special condition and codifies some redundancy requirements. If this section applies to the facility, review carefully because it might limit the design options.

Designing redundancy for mechanical systems may not be as straightforward as the electrical system. Chillers and air handlers don’t require a binary solution like the electrical system. The goal is to adjust the size and quantity of units to operate the units at efficiency while maintaining the required redundancy.

The routing of chilled water pipes and the number of cooling units must be considered. Will there be a looped chilled water system or redundant pathways? How many and where do the isolation valves go? When working through these issues overhead space and the mechanical plant layout have a lot of influence on the design.

Controls for the mechanical system are vital in buildings like these. Monitoring the health of the equipment and distribution system makes it much easier to react to issues. The number of controllers and how each interacts with physical equipment can make or break the system during an event. How controllers are powered is an important question to resolve. Will the controller have an internal battery to run through a power failure or will it be backed by a UPS?

Once the redundancy of the electrical and mechanical systems has been established, the design must coordinate how the systems interact with each other. Will a power failure on the A electrical side bring down the mechanical plant? If an air handling unit fails, will the electrical room overheat? It’s important to walk through each system, play out a failure, discuss how it effects the other systems around it and potentially revise the redundancy.

Implementing resiliency

For Quarry Run Regional Operations Center, the design team gathered input from call takers, supervisors and managers in a two-week programming exercise — an initial design phase that defined the facility’s functional and operational requirements and culminated in a floorplan. Because of its unique function as both a call center and potential emergency operations center, Quarry Run has a more complex infrastructure than virtually any other building type. It is a workplace, with typical office requirements. In an emergency, it becomes a high-security operations center capable of crisis management and sustained emergency communications with first responders.

The building’s hardened core contains the PSAP, emergency operations and network operations center, two data centers and all the redundant engineering systems that support these elements. Power supplies coming to the 13,000-square-foot PSAP floor are fully redundant, uninterruptable and designed to run for several day in the event of an outside utility failure.

The space is organized for maximum efficiency and call taker comfort. A video wall of 56 large screens displays television news, building security cameras and call statistics, as well feeds from Texas Department of Transportation highway cameras and video from the San Antonio Police Department and Texas Department of Public Safety helicopter units. Lights are kept low to reduce glare and eyestrain. Tuned acoustics absorb the sound of chatter and keep ambient noise to a minimum. The 104 Airbus Vesta-equipped 911 workstations have duplicate screens that are fully ergonomic and located on a raised floor to allow easy access to the mechanical equipment underneath. The consoles have sit/stand functionality and individual temperature and lighting controls, so call takers can create the preferred work environment.

Supervisor offices line the PSAP floor on three sides and emergency operations can take over a second-floor conference room that overlooks the PSAP floor. From this vantage point the entire PSAP floor, the call takers’ computers and wall of screens opposite are in view and appear like the bridge of a starship in science fiction movie. Windows are tinted for privacy and can be rendered transparent with the punch of a secured button.

Supporting this hub from deep inside the core are two data centers designed to ANSI-TIA-942 Tier III standards. Mechanical and electrical systems will automatically respond to failures without creating a system outage on the PSAP floor. A computer monitoring and control system allows constant, real-time, at-a-glance monitoring of every component in the system at any time. Even water tanks were designed to withstand ballistic forces to guarantee clean water supply to workers in the event of an extended emergency.

The MEP courtyard is itself protected by a breathable steel-grate roof that provides protection from wind and flying debris in a tornado rated as high as EF3 (with 165 mph winds). A helipad rounds out the building’s emergency capabilities.

A highly sophisticated and fine-tuned machine, the facility is designed for the worst-case scenario. Every eventuality was considered and addressed. The ability to adapt and overcome the faults when the time comes is the real test of resiliency. Quarry Run’s survivability and resilience of its systems are its reason for being, but the client serves a larger purpose: Peace of mind for the public it serves.

Resilient enough

Designing resilient systems can be fun, but engineers must avoid going overboard. Systems should be reviewed against resiliency goals of the project to ensure the goals have been met without going too far. When reviewing the systems, make sure that each redundant component or pathway has a purpose and serves that purpose. Designers may determine that system is stronger if a pathway is removed, which makes the overall building stronger, too.

It’s also important that, at the end of construction, each one of these components and systems gets commissioned. The systems need to be fully tested and vetted by an independent third-party tester to ensure that everything operates as designed. The first time a system operates should not be during the event it is supposed to survive.

Buchholtz led the agency through a series of soft openings, another opportunity afforded by the project’s lack of a hard deadline. As a result, the PSAP went live without a hitch. “We didn’t have to be ready until we were ready,” said Buchholtz.

Page principal Freddy Padilla said, “Keeping your critical equipment safe is key when you are looking to provide such important service to the public during a natural disaster.” A highly sophisticated and fine-tuned machine, the facility is designed for the worst-case scenario, according to Padilla. The significant investments in resiliency and double infrastructure are the heart of its innovation.

Author Bio: Cameron Brown is an associate principal and electrical engineer at Page.