Water-Based Suppression for the
New Indianapolis Airport

NFPA Journal®, July/August 2008

By Gary E. Mohr, C.P.D.

When you’re the home of the Indianapolis 500, you like to do things fast, and you don’t like anything to get in your way of the finish line. That’s why, when Indianapolis decided to replace its airport, it did so with speed and efficiency in mind. In fact, the city is building the new airport right where the old one is while it is still operating.

That’s not an easy task for a busy airport. More than 8 million people pass through the airport each year, and it ranks eighth in the country in terms of cargo shipments. When completed in late 2008, the $1.1 billion New Indianapolis International Airport will be among the most sophisticated in the nation.

Building a new transportation gateway
The existing airport terminal, built in 1928, has been expanded since the 1950s with various addons. The last concourse was built in the 1980s. The new terminal, which is being built in the midfield between the airport’s two runways, will reduce the notoriously long time planes now spend taxiing to gates. It will feature about 55,000 square feet (5,110 square meters) of retail space for shops and concessionaires, about 30,000 square feet (2,787 square meters) of which will be located beyond the security checkpoint.

In addition to the new terminal, the New Indianapolis Airport will have two concourses, A and B. Each concourse will have 20 gates for a total of 40 gates, as compared to 33 at the existing airport. Overall, the terminal will be four stories high. Level 1 is the Arrivals level at the terminal building, and its finished floor elevation is 758 feet (231 meters). Level 2 is the mezzanine level in the terminal baggage hall, and its finished floor elevation is 775 feet (236 meters). Level 2’s apron for the concourses has a finished floor elevation of 778 feet (237 meters). Level 3 is the Departures level at the terminal building and the concourses, and its finished floor elevation is 792 feet (241 meters).  Level 4 is the office level, with two mechanical equipment rooms, and its finished floor elevation is 809 feet (247 meters). Levels 5 and 6 are various roof levels and mechanical equipment rooms. The highest point of the terminal’s roof is 871 feet (247 meters). The roof covers more than 5 acres, and its elevations vary due to its unique saddle shape.

The sprinkler system design
The airport is equipped with a number of large water mains. A 24-inch (61-centimeter) water main runs cross-field from south to north between the existing airport and the new airport, from which extend to the west two 20-inch (51-centimeter) water mains. Each 20-inch (51-centimeter) main flanks the north and south concourses. The two mains are cross-connected in front of the terminal building with a 20-inch (51-centimeter) water main, and a 12-inch (30-centimeter) combination fire and domestic water main extends from the 20-inch (51-centimeter) water main into the fire pump room in the terminal.

The design criteria used for the terminal fire protection systems are based on the latest enforced edition of the applicable codes, an initial flow test before the water main extension, and a current flow test from new hydrants in front of the terminal building. The fire protection codes being used include the 2000 editions of the International Building Code (IBC) and the International Fire Code; the 1999 edition of NFPA 13, Installation of Sprinkler Systems; the 2000 edition of NFPA 14, Installation of Standpipes and Hose Systems; the 1999 edition of NFPA 20, Installation of Stationary Pumps for Fire Protection; the 1995 edition of NFPA 24, Installation of Private Fire Service Mains and Their Appurtenances; the 2002 edition of NFPA 415, Airport Terminal Buildings, Fueling Ramp Drainage, and Loading Walkways; and the 1994 edition of NFPA 2001, Clean Agent Fire Extinguishing Systems.

The initial flow test was actually taken south of Interstate 70 off of the project site. Preliminary calculations were performed and later revised when more definitive information became available. The areas protected by the automatic sprinkler system include the pedestrian bridge, terminal building, and the two concourses. There are 14,200 sprinklers and 2.5 miles (4 kilometers) of fire protection main piping.

The building will have a combined automatic standpipe and sprinkler system throughout, supplied by an automatic fire pump and related jockey pump. The automatic fire pump will be supplied by two independent water services, with an approved double check valve assembly, and connected to a water main provided with a sectional valve.

All floor areas are protected by fire department valves (FDVs) located inside each entrance to an exit passageway, at the main entrances to the terminal building, and in exit stairwells and other locations, as required by code. The FDVs will be 2 1/2 by 2 1/2 inches (6 by 6 centimeters) with a 2 1/2- by 1 1/2-inch (6- by 4-centimeter) reducer coupling and a 1 1/2-inch (4-centimeter) cap and chain. FDVs will be on combined standpipe risers at the intermediate level of the stair towers. Fire hoses and nozzles are not provided. Fire department connections are located on the exterior wall of the terminal building at grade level.

The sprinkler system is zoned per floor, and each floor is subzoned into areas that do not exceed 52,000 square feet (4,831 square meters), with control valves and water flow switches for each zone.

Quick response sprinklers are located throughout the building complex. Automatic wet-pipe standpipe flow demand will be 500 gallons (1,893 liters) per minute to the most remote standpipe and 250 gallons (946 liters) per minute minimum for additional risers, with the total not to exceed 1,250 gallons (4,732 liters) per minute. Residual pressure at the highest and most hydraulically remote fire hose outlet will be 100 pounds of pressure per square inch gauge (psig). Fire extinguishers are provided in each retail space, within 30 feet (9 meters) of all the commercial cooking equipment, and in each storage, maintenance, mechanical, and electrical equipment room.

Sprinkler systems for specific areas
The airport has sprinkler systems appropriate for the area within the building and for the way that area is used. For areas designated as tenant spaces, there are two occupancy classifications as specified by the IBC: Ordinary Hazard Group 2 Occupancy for kitchens, concession areas, and storage areas, and Ordinary Hazard Group 1 Occupancy for all other areas. In cooking areas with hoods, there is a pre-engineered approved type fire suppression system supplied as part of the hood package. Unfinished areas without suspended ceilings have upright sprinklers. In finished areas with suspended ceilings, concealed sprinklers with cover plates are provided. Friction-fit cover plates are not allowed. And around the civic plaza and mechanical equipment rooms 212°F (100°C) heads are provided.

A sprinkler system is installed throughout the baggage area, including the spaces above and under the conveyors, under the catwalks, and in other locations. All obstructions to sprinkler coverage were considered, as required by NFPA standards.

Building service chutes are also protected internally by automatic sprinklers. A sprinkler is placed above the top service opening of the chute, above the lowest service openings at alternate levels in buildings over two stories high. The room or area into which the chutes discharge is also protected by automatic sprinklers.

A Novec 1230 clean agent system is installed in the local area network room, the public address system room, the main communications rooms, and the airport communications rooms.

The water supplies
Care was taken to ensure the best hydrant location for the fire service. Hydrants are located between the terminal and the parking garage. Two of them were tested and used as a design basis for hydraulic calculations.

Hydrant #1 static pressure is 70 psig, with a residual pressure of 57 psig, and Hydrant #2 has a flow rate of 1,190 gallons (4,505 liters) per minute. The fire pump curve is 1,250 gallons (4,732 liters) per minute at 130 psig.

Several types of automatic sprinkler systems are used at the new airport. The wet-pipe system is a combination automatic sprinkler/standpipe system with 2 1/2-inch (6-centimeter) FDVs located at the intermediate stair landings and floor control assemblies located at the ceiling of each floor to cover main zones and subzones. The FDVs are rotated at a 45° angle to accommodate 2 1/2-inch (6-centimeter) fire hoses when connected.

Double-interlocked pre-action systems are used where expensive equipment, such as uninteruptible power supply rooms, the public address system, the motor control room, the north and south baggage halls, and the baggage handling system control room, is being protected. A preaction system is also used for the water curtain at the entrance to the terminal from the pedestrian bridge at the Departures level, which links the parking garage to the terminal. A water curtain system provided at the connection of the pedestrian bridge to the terminal is supplied from the terminal combination sprinkler/standpipe system. A water curtain system is also provided at the other end of the pedestrian bridge where it connects to the parking garage. It is supplied from the garage system.

A dry-pipe system serves the loading dock. That is the only location for a dry-pipe system. For the dry-pipe systems and pre-action systems, the area of sprinkler operation will be increased by 30 percent without revising the density.

The civic plaza is a multifunctional space 200 feet (61 meters) in diameter. The distance from the plaza floor to the roof is 80 feet (24 meters). Since the entire roof of the civic plaza is a large skylight and there is no place to put sprinklers or piping, the decision was made to use water cannons.

There are four water cannons, one in each quadrant of the plaza. They are mounted at the top of the perimeter of the rotunda, at a point 40 feet (12 meters) above the floor. Each water cannon is angled so that its discharge pattern covers 120 feet (37 meters) from the edge to the center, overlapping 20 feet (6 meters) from each quadrant. Each water cannon is supplied from a deluge system that uses four triple, infrared flame detectors and beam detector transmitter and receivers located strategically around the plaza.

The fire pump is sized for 1,250 gallons (4,732 liters) per minute, the maximum allowed by NFPA 14. The pressure is calculated to have a static head of 103 feet, 8 inches (31.5 meters) or 45 psig. The top-of-riser pressure will be 100 psig, and the pipe and fitting loss is estimated to be 15 psig. The pressure loss from the static head is 160 psig, but the 30 psig available from the city main reduces the required pressure boost to 130 psig. The fire pump is equipped with a 150-horsepower, 3,550-rpm, 460-volt, 3-phase, 60-Hertz motor. Since the pump will churn at 216 psig discharge pressure, 250 psi flanges are provided on the discharge of the pump, which is equipped with a solid-state, soft-start controller. The jockey pump will provide 15 gallons (57 liters) per minute at 140 psig and will have a 5-horsepower, 460-volt, 3-phase, 60-Hertz motor.

The most difficult challenge of this project was designing the water cannon system. Special attention was given to selecting the type of water cannon and the type of heat and smoke detectors. Due to the unusual shape of the area being covered, only a functional test, and not a water test, will be performed.