Fire protection at 90 South
By Samuel S. Dannaway, PE,
President, S.S. Dannaway Associates, Inc., Honolulu
Last month I had the opportunity to return to Antarctica where I was part of a team responsible for final commissioning of the recently completed South Pole Elevated Station. My role was the commissioning of the fire protection and life safety systems. This article will briefly describe the fire suppression systems that are provided for this facility.
The facility is owned by the National Science Foundation, which for several years has been modernizing their facilities at the station. The new South Pole Station provides a state-of-the-art facility for housing, food service, maintenance, administration, and other functions in support of the National Science Foundation research programs at the South Pole.
The station is occupied and operated year round, but is most active in the summer season from October to February, at which time the station is occupied by 200 to 250 persons. During the summer, a constant stream of LC-130 Hercules cargo planes ferry personnel, cargo and fuel to the station from McMurdo Station, a facility located on Ross Island just off the coast of Antarctica. A smaller “winter-over” crew of about 40 to 50 persons maintains the station during the seven months of harsh winter weather in which conditions are too harsh to permit aircraft to land at the station.
The new South Pole Station was designed for NSF under a contract with the Naval Facilities Engineering Command, Pacific Division at Pearl Harbor, Hawaii. The project architect was Ferraro Choi Associates, Ltd. of Honolulu, Hawaii. The design of fire suppression and fire alarm and detection systems for the facility was provided by PDC Consulting Engineers of Anchorage, Alaska. The project was constructed by Raytheon Polar Services of Denver.
The station consists of a two-story elevated portion which includes berthing, food service, offices, a science lab, hydroponics garden, recreational spaces (including a small gym and basketball court), an emergency power plant and other support spaces. The elevated station is supported by columns several feet above the ice surface. The station is elevated to delay the inevitable inundation by the accumulating snow pack. To further extend the life of the station the building exterior has an aerodynamic design which helps prevailing winds slow the accumulation of snow beneath the structure. Also, the station structure also can be raised with a system of jacks to add even more service life to the building. Adjacent to the elevated portion are arched structures now buried in the snow and ice, which contain the main power plant, warehouse facilities, fuel storage, a vehicle maintenance garage, and shop facilities.
The total floor area of the elevated station portion is approximately 65,000 square feet. The station was constructed in two phases, Pod A and Pod B. Pods A and B, each containing half of the station, also correspond to the two major fire areas of the elevated station. The pods are separated by a two-hour fire barrier. The fire barrier also serves as a horizontal exit enabling building occupants to use either of these areas as an area of refuge from an incident involving the other area.
The elevated station is provided with automatic sprinkler protection throughout. The sprinkler system is a preaction system arranged primarily as a double-interlock preaction system. Though all sprinkler system components are located in heated areas, a preaction system was used in the event of an accidental loss of heating to a portion of this very large structure.
The water supply for the sprinkler system consists of a stainless steel pressure tank containing approximately 5,000 gallons of water. A dedicated air compressor maintains a pressure of 150 psi in the tank. This air compressor also provides the supervisory air supply for the preaction system piping.
The elevated station sprinkler system has three preaction risers. One riser serves Pod B and two preaction risers serve Pod A. In Pod A, one preaction system covers the kitchen and dining area. A second system provides protection for the remaining portion of Pod A.
Sprinklers are closed head, quick response-type sprinklers. With the exception of the risers, which are galvanized steel, the piping consists of Type L copper tubing.
There are three occupancy hazard classifications identified. The berthing areas, offices, recreation and dining areas are considered light hazard. The kitchen and utility spaces are considered ordinary hazard Group 1. Storage areas are considered ordinary hazard Group 2. The system is hydraulically designed using the density/area method of NFPA 13.
The preaction valves are controlled by the fire alarm and detection system for the elevated station that provides automatic detection in all spaces. Open area photoelectric smoke detectors are provided in most areas, including sleeping areas, offices, corridors and the dining area. Heat detectors are provided in storage areas and certain utility and shop spaces. All control valves are monitored by valve tamper switches. Each preaction system also contains supervisory air and is monitored by a low air pressure switch.
The preaction valves are provided with electric actuation trim. The preaction valve serving the kitchen and dining areas is arranged as a single interlock system. The preaction valve is activated by operation of a single automatic detector. The other two preaction valves are arranged as a double interlock system. Valve actuation requires the operation of both an automatic detector and the operation of the low air pressure switch.
There are also other fire suppression systems and equipment in the elevated station.
Wet chemical fire extinguishing systems are provided in the kitchen for the two kitchen exhaust hoods. The two emergency generators in the emergency power plant are protected with a local application carbon dioxide fire extinguishing system. This system is activated manually by CO2 release stations and automatically by cross-zoned heat detectors.
Portable fire extinguishers are located throughout the facility. General use extinguishers consist of multi-purpose dry chemical stored pressure extinguishers. Clean agent extinguishers are also located in areas where appropriate.
Fire suppression systems and equipment for the South Pole Station work with the fire alarm and detection system, other fire protection features provided in the station construction and an emergency plan to provide life safety at the southern most location on our planet.
Samuel S. Dannaway, PE, is a registered fire protection engineer and mechanical engineer and past president and a Fellow of the Society of Fire Protection Engineers. He is president of S. S. Dannaway Associates, Inc. He can be reached at SDannaway@ssdafire.com.