CONCRETE
THE RESCUE COMPANY
Concrete is a building component that figures prominently in our firefighting and rescue operations. Our experience with concrete runs the gamut from making openings for hose streams to the much larger rescue operations involving tons of concrete.
At times it is necessary to breach walls to reach trapped victims. Access openings in piers or wharfs during fires are usually required for underpier nozzles or distributors, which provide a very effective means of reaching fire not accessible from above.
Cellar and subcellar fires can create unique firefighting problems. Just advancing into a cellar and its fire usually pushes firefighters to the extreme, and then they find that the fire is still a level below the area they have reached. Incident commanders usually order openings made in the concrete flooring for the use of cellar pipes, distributors, bent tip nozzles, and so on. Breaching side walls is another tactic used to reach inaccessible areas. Tactics used in high-rise incidents often require that openings be made through concrete flooring for ventilation purposes and hose stream penetration.
One of the most challenging rescue operations is structural collapse. According to the American Society of Civil Engineers committee on damaged and failed structures, there have been at least 500 large building mishaps every year for the past 10 years, many of which involved concrete structures. Fortunately not all involved such a high death toll as the following major incidents:
- In the Oakland area, firefighters responding to the collapse of Interstate 880 during the October 1989 earthquake found that almost 1 1/4 miles of the freeway’s upper deck had collapsed onto the lower section. Rescue workers teamed up with construction workers and spent five days clearing tons of concrete rubble.
- In the December 1988 earthquake in Armenia, which left more than 25,000 dead and demolished entire towns, rescuers faced a similar challenge: tons and tons of concrete rubble with numerous victims trapped underneath.
- The collapse of the “L’Ambience Plaza” high-rise apartment building under construction in Bridgeport, Connecticut in April 1987 killed 28 construction workers; rescuers spent 10 days digging through hundreds of tons of concrete and metal.
- Another high-rise construction collapse of eight-inch concrete flooring occurred in Fairfax County, Virginia in March 1973, killing 14 workers.
- One of the most tragic incidents involving concrete occurred at the Hyatt Regency Hotel in Kansas City in July 1981: 114 people were killed and
- 200 injured when a 145-foot-long “sky bridge” at the fourth-floor level collapsed onto a similar sky bridge at the second-floor level, sending both crashing down onto a crowded dance floor. It took Kansas City rescuers 12 hours to dig out the victims from beneath the concrete rubble.
How can rescuers deal with the problems presented by concrete? What tools and equipment are necessary for dealing with these incidents? In March 1989 a program sponsored by the Urban Search and Rescue Working Group in association with the National Association for Search and Rescue was held at the University of California in San Diego. Rescue workers, municipal workers, and manufacturers tested and evaluated equipment for cutting and lifting concrete slabs. Jack hammers, saws, and cutting equipment were tested on concrete slabs 14 inches thick, 2 feet wide, and 9 to 12 feet long. The results varied according to the type of equipment used (larger commercial equipment compared with small portable types used by rescuers). Depth penetration, speed, and ease of handling also were considered.
THE RIGHT TOOLS FOR THE JOB
What is the best type of tool/equipment for your unit? That depends mainly on the type of response area and the construction features of the buildings in your area, but also evaluate the following: What other equipment carried on the apparatus is capable of doing this type of work? How much space is available on the apparatus? (Large jack hammers and generators or compressors can take up a lot of space.) How big is the department’s budget allocation for this type of equipment?
The tools/equipment available that are capable of penetrating any type of concrete come in many sizes, shapes, forms, and power sources. For example, a jack hammer (pavement breaker) can be powered electrically, hydraulically, and pneumatically. Most utility companies and municipal departments use large air compressors that are transported to the job site by trailers or trucks. This provides a power source close to the operational point, cutting down on any power loss.
There is a unique pneumatic breaker on the market that weighs only 11 pounds, is designed to operate from any air source, and delivers 40 to 250 psi, depending on the material to be penetrated. It will operate continuously for seven minutes from a full 30minute air pack cylinder. It can be used to breach walls or penetrate concrete floors.
Electrically operated pavement breakers powered by generators can be taken to cellars or upper floors of a high-rise in place of compressor-supplied, air-operated tools. Because of their versatility, these pavement breakers are prevalent in the fire service, as are the hydraulically operated ones. These tools are easier to set up, quieter, less fatiguing, and cleaner to operate. They are available in different sizes (overall weight and power capabilities).
Power saws with a silicon carbide blade also are capable of cutting concrete. In the California test a ring saw that uses an off-center blade drive system was used. The system has a 14inch blade that cuts to a depth of 10 inches.
Another unique tool available for use on concrete is a water drill that uses water from a pumper both as the power medium for the drill bit and as an extinguishing agent. It is attached to a 1½-inch line; when operating at a pump pressure of 200 psi, the diamond core bit cuts all masonry products including reinforced concrete.
The New York City Fire Department uses a concrete core cutter designed originally for use in high-rise buildings. Electrically powered from a house current or generator, it uses an 8-inch-diameter diamond core bit (12 inches long) that can cut through 48 inches using extensions at the rate of one inch per minute. Using a telescoping floor-to-ceiling column support, it can be used to cut overhead through a ceiling, laterally through a wall at 90 degrees, or downward through the floor. Because of its size and weight, it is mounted on a wheeled platform and can be moved easily from one location to another.
As in all rescue operations, it is necessary to drill and train with tools and equipment so that the rescuers become familiar with it, its capabilities, and its limitations. Remember, the scene of an operation is not the time to test equipment.
