PDC is currently providing mechanical, electrical, and fire protection consulting services for a new regional Search and Rescue (SAR) hangar for the North Slope Borough (NSB) located in the extreme arctic climate of Barrow, Alaska. The 35,000 sf facility will house the NSB’s two medical evacuations airplanes and two SAR helicopters along with the support services of aircraft maintenance; 24/7 pilot standby; mission planning and support; and day-to-day administrative offices.
At the outset of the project, the team performed a condition survey of the existing 1980s era hangar including its code compliance, infrastructure, systems, and capability to accomplish SAR’s mission going forward in a rapidly changing arctic environment including the addition of a new helicopter.
Multiple concept designs were developed and priced to renovate/expand the existing hangar as well as several new facility configurations on an adjacent parcel next to the existing hangar.
Based on the team’s analysis, NSB opted to build a new hangar as it presented the best opportunity for cost savings; improved facility lifespan through design for arctic conditions; greater energy, space, and functional efficiency; reduced disruptions during construction; and increased capacity for future operations.
An early design package was completed for site development and the installation of piling and thermal-syphon system. PDC completed early design calculations and concept layouts to provide equipment weights, utility requirements, and site development infrastructure to support the Phase 1 design package.
The team started the Phase 2 hangar design with a full day mechanical, electrical, and fire protection charrette in Barrow with key stakeholders and users including NSB project management, SAR administration, maintenance, pilots, and local utilities. The charrette provided the team a clear direction on the client’s design priorities and the MEP system design solutions.
MECHANICAL: The mechanical system design focus was on providing systems that will support the SAR mission while minimizing the long-term operational costs of the facility. An example of this was designing a simple, durable design with redundancy for the heating system while incorporating low-maintenance, non-condensing gas boilers and energy-efficient variable speed drives for distribution pumps. The hangar heating system used multiple high-bay, gas-fired radiant tube heaters to provide energy efficiency and minimize stratification. The hangar ventilation system includes 100-percent air-to-air heat recovery; gas-fired duct coils to minimize central heating plant size; and an innovative delivery system above the hangar doors that doubles as an air-curtain when the hangar doors are open. This will greatly reduce heat loss during the frequent moving of aircraft in and out of the hangar. The hangar heating and ventilation strategy is supplemented by two large destratification ceiling fans. The ventilation for the administrative wing is supplied by a 100-percent, air-to-air heat recovery unit coupled with a displacement ventilation distribution system which greatly reduces energy usage and improves employee health. The plumbing system incorporates low-flow fixtures, trench drains and oil-water separator for the hangar, and a compressed air system to support the paint booth, shop, and hangar areas.
ELECTRICAL: The electrical design consists of providing lighting, communications, and utility and generator backup power to the new search and rescue facility.
- Lighting: Lighting for this project was 100-percent LED and ranged from general office type lighting to artwork-type lighting to exterior parking lot and aircraft hangar lighting. The user comfort was balanced with basic functionality of the facility to produce a very mixed lighting style and design.
Energy efficiency was also a key factor for this project and several steps were taken to reduce the overall energy load of the facility. One of these steps was to install a building-wide central low voltage lighting control system to automatically lighting off time during periods when spaces are not occupied. The majority of lighting in the facility is also fully dimmable, which enables the individual users to control lighting to their personal preference. The initial lighting control system was set to turn on lights to 60-percent illumination upon that particular space being occupied and giving the user the ability to increase to 100-percent illumination via a dimmer switch, if desired. Studies have shown that the majority of the time a person will be comfortable with the decreased lighting level thus saving 40-percent of energy within these spaces. All exterior lighting is automatically controlled on/off via a photocell linked to the dawn/dusk cycle.
- Power: Power for the facility consists of a main electrical utility served from the local utility, BEUCI. This facility supports rescue operations throughout the North Slope of Alaska and is considered highly critical to the needs of the community and continuity of electrical power was at the forefront of the design. Therefore the facility was designed with a backup power supply for both the entire facility and a separate UPS system for the telecommunications systems. The entire facility is provided with a standby generator which is a natural-gas reciprocating-style, rated 200KW.
There was careful analysis performed in evaluating a micro-turbine generator versus the reciprocating unit that was chosen. However, even considering the co-generation a micro-turbine provides, the reciprocating design was chosen as the final selection. This was based primarily on the plentiful supply and the low cost of natural gas in Barrow along with other political factors with the local electrical utility. Another design feature to reduce energy consumption is the design of parking lot headbolt heater receptacles that vary the output load based on outside ambient temperature. These have been shown to be very effective at reducing overall energy costs in climates such as Barrow, Alaska where long season temperatures range from -20 F to +20 F.
Communications: Communications for this facility was brought in from an existing campus facility via an overhead outside plant single-mode fiber optic line. The fiber line was brought into a main telecommunications room where it was converted for distribution throughout the facility via CAT 6 copper cables. Because of the critical nature of the SAR facility, it was provided with a full electronic access control system outfitted with security cameras. There is also a radio communications link that was designed for this project and which is vital to the mission of the facility.
FIRE PROTECTION: The fire protection design included code compliance research for the complex requirements of an aircraft hangar and enclosed painting room for large objects. The hangar suppression system included a complete wet sprinkler system in conjunction with high expansion foam (HEF) generators and manual hose stations. Clean-up after a HEF discharge was taken into account including the selection of the chemicals so that it would not have a negative impact on the utility’s wastewater treatment plant. The rest of the building is provided with a traditional wet-head sprinkler system with dry-heads used at overhangs and those areas within the building subjected to freezing conditions such as the entry vestibules. A 100 hp fire pump (with jockey pump assist) provides 1,750 GPM of water to the building sprinkler and hangar HEF system. The paint booth was specified with a packaged dry chemical suppression system.
The fire alarm system for this facility provided building notification strobes and chimes throughout the office areas and separate notification strobes and horns for the HEF system in the hangar. External strobes were design to FAA regulations regarding lighting devices facing airfields. Due to high temperature swings and overhead radiant heating devices, rate compensated heat detectors were used in the hangar space to prevent false activation signals from traditional detectors.
COMMISSIONING: PDC is providing the commissioning services on the project as well as being involved in submittal review, site observation, test witnessing, and general support as the project is installed, and tested.
PROJECT CHALLENGES: The project balanced the critical infrastructure requirements of a regional SAR facility while minimizing operational costs while also meeting a demanding design schedule and limited budget. Phased construction was used to realize the winter construction season for pile installation and summer construction season for vertical construction.