BY FRANK MONTAGNA
What problems will you face if a large water main in your response area bursts? At your next burst water main incident, you won’t have to deal with all of the challenges below at once, only some of them. Since you can’t know which ones you will encounter, consider the problems outlined below and how you might resolve them before you have to respond.
Why Water Mains Burst
Water mains suffer damage and burst for a number of reasons, most commonly the damage resulting from construction, the freeze/thaw cycle in areas with severe winters, old age, or some combination of the three. A burst water main can have far-reaching consequences and affect several occupancies.
Let’s consider that a freeze/thaw cycle of several days has caused a large water main to rupture at 4:30 a.m. on a frigid February weekday morning. As you arrive, you see water streaming down a slightly graded roadway for several blocks. At the bottom of the hill, the water is collecting and has already formed a small lake. The break occurred in the center of town and the water threatens private dwellings, a strip mall, several other commercial buildings, and a four-story apartment building. Ice is already forming along the edges of the affected area.
|(1) Water flowing from a burst water main flows not only on the surface but also below it, undermining the street. Is this water only a few inches deep or does it conceal a deep sinkhole? (Photo 1 by Thomas Bierds; other photos by author unless noted.)|
An unlimited supply of water is rushing down the streets, and until appropriate action is taken, you will face an endless stream of water. But the water you see may not be the only problem-water is also flowing underground. You will have to notify the water department, which will need to locate and close possibly several valves, one or more of which may be underwater at the bottom of the hill. How long will the water department personnel take to respond, and once they arrive, how long will it take them to stem the flow of water? Your problems will continue to escalate until they accomplish this task.
Life Safety Hazards
Sinkholes and Road Collapse. The water escaping the confines of the main is likely creating unseen havoc underground. As the relentless subsurface flow of escaping water undermines the roadway, the pavement can collapse, creating sinkholes that fill rapidly with water. These flooded sinkholes, though present, may not be evident because they are hidden by the water flowing on the street’s surface and may appear to be just puddles. Firefighters stepping into a sinkhole is a real hazard, and we know that they don’t float well in bunker gear. If you must walk in the water, test the pavement in front of you with a tool to avoid inadvertently stepping into a water-filled hole (photo 1).
When investigating a reported water main break, do not drive into the water with your apparatus. There have been several instances of apparatus getting stuck in unnoticed sinkholes. Stop a distance back from the water. How far back should you stop? I could tell you to keep yourself and your apparatus 10 feet away from the edge of a sinkhole and that would be good in most cases, unless the undermining was extensive or a sinkhole already existed unnoticed under the water (photo 2). After parking, walk to the site, carefully noting the condition of the sidewalk and street. Follow the flowing water to its source; look for water bubbling up out of the pavement, which might indicate the location of a subterranean leak.
|(2) Keep all but the most necessary personnel away from the edge of the sinkhole.|
As the water continues to flow, an existing sinkhole’s boundaries will continue to erode, and additional pavement may collapse. Once the water flow is curtailed, determine and stay away from the edges of any sinkholes, since they might not support your weight (photo 3). At one incident, a firefighter unknowingly stepped into a sinkhole; at another, a water department worker fell into a sinkhole as the edge of the pavement collapsed. Luckily, both were rescued. Keep firefighters out of the water and away from sinkholes as much as possible, and keep all civilians and all vehicles clear of sinkholes and any flowing and collecting water.
|(3). A broken water main has left a water-filled sinkhole that public works personnel are pumping out. At night, flowing water would hide the hole. A firefighter could easily step into the hole if he was careless enough to enter the water without probing ahead with a tool as he walked. (Photo by Lloyd Mitchell.)|
Curious Neighbors. You must prevent the curious neighborhood residents from entering the danger areas, a problem that will increase as people wake up and start leaving or returning to their homes as they go about their day’s business. Curiosity will compel some to get a close look at the goings-on, and there is the ever-present danger of one falling or driving into a sinkhole. Initially, firefighters can bar curious onlookers from the danger areas, but as soon as possible, assign the police to this task to free firefighters for other assignments.
Vehicle Traffic. Since undermining may have already occurred undetected and a sinkhole might open up, you must stop vehicular traffic in the area. The added weight of any vehicles, including fire apparatus, can collapse undermined pavement. Undermined pavement may have no outward indications. Although a car might drive safely over a section of flooded roadway, the next car or a heavy bus or truck might cause the undermined roadway to collapse. I responded to a water main break and found a garbage truck half submerged in a sinkhole (see “Truck Extrication from a Sinkhole,” What We Learned, Fire Engineering, April 2002, 30-36, http://bit.ly/1hyJXGB).
In photo 4, the driver thought that he was only driving through a puddle when, to his surprise, his front wheels left the pavement and his truck started doing a credible imitation of the Titanic. The vehicle’s two occupants were able to get out of their truck and to safety. Responding fire trucks have also inadvertently driven into sinkholes or been trapped by a newly developing one. Parked cars also can suddenly slip into expanding or newly developing sinkholes.
|(4) The truck’s driver drove into what he thought was a puddle, but it was actually a sinkhole created by a burst underground water main. The undermined roadway collapsed under the truck’s weight.|
If you come upon a vehicle wholly or partially in a sinkhole, consider that its occupants might be trapped. A moving car or truck driving into a sinkhole usually sinks with the nose angled down. If the side boundaries of the hole are close to the sides of the vehicle, the doors may be jammed shut. The trapped occupants may thus require extrication through the windows.
If possible, stabilize the vehicle with ropes or chains so that it does not sink farther into the hole. Secure any firefighters entering the water with ropes, and consider that in this situation, it might be safer for them to operate without bunker gear, considering how quickly the gear may drag firefighters below the water’s surface. The various vehicle fluids-fuel, oil, and the others-can seep into the water and find their way back into the water main, contaminating it. Also, a burst water main can also damage sewer lines. In either case, the incident would now become a hazmat incident, necessitating the decontamination of anyone exposed.
Once the vehicle is stabilized, if any fluids are leaking, it may be possible, even advisable, to offload fuel. The garbage truck was leaking diesel fuel from a damaged tank, so we offloaded the fuel to reduce any possible spillage into the water. However, this task may be too dangerous to perform. As we pumped the fuel into a drum, the truck continued to settle deeper into the water, putting the firefighters near the truck at risk of injury. The water department did not want to completely stop the flow of escaping water, because doing so would result in contaminated water back-flowing into the water supply system. We had to add water to the sinkhole once the water department stopped the flow to keep the vehicle fluids floating on the water’s surface above the pipe below.
|(5) To remove the truck, a crane lifted the front of the truck while a tow truck stabilized the rear to keep it from being pulled into the hole by the crane. The hoseline maintains the water level above the shut-off water main to prevent contaminants on the water’s surface from back-flowing into the water supply.|
Removing the truck from the water took some time to arrange. First, the sanitation department tried to hook up a heavy tow truck to the rear of the garbage truck and pull it out of the hole, which it was unable to do. We requested a large crane, which raised the front of the truck up and out of the water, so the tow truck could pull the vehicle out. Keep in mind, these heavy tow trucks must stay a safe distance away from the edge of the sinkhole or they might collapse the pavement and fall into the hole too (photo 5).
Trapped Vehicle Occupants. If there are any below-grade areas along the roadway, pooling can occur, trapping unwitting motorists in their cars. People have proven time and time again that they are willing to drive through puddles of unknown depth, which gets them into trouble. The water level can rise quite rapidly, depending on the size of the broken main and the area of the below-grade roadway. Once, cars were stranded on a road that passed through Central Park in New York City. The road had high walls on either side. A park reservoir pipe ruptured and a veritable river flowed through the road and out onto Fifth Avenue, sweeping any cars on the park road into a below-grade portion. The water in that section rose up to the vehicle’s windows. Although many occupants had self-evacuated, the responders still needed to enter the water and check each car for trapped victims. You will have to check all the cars in a flooded area for trapped occupants. Trapped Building Occupants. Since our incident occurs at a time when most people are sleeping, it is possible rising floodwaters might trap any sleeping, young, or invalid occupants in their homes. Those on the first floor or in the basement might be in immediate danger if water is entering the building. Entry into some basements and cellars may be dangerous or impossible because of the depth of the water and the possible electric shock hazard. When the water level in a building reaches the electrical outlets or any electrical appliances or equipment, the water may become electrically charged, posing a danger to anyone entering it.
Anyone using life-support equipment might need medical assistance if the equipment loses power or if the rising water damages it. The electric utility, the police department, or the apartment building’s management may keep a list of people on life support equipment. Obtain this list early in the incident; it could help you quickly reach them with the needed assistance. Check stalled elevators in flooded buildings for stranded passengers, and remove any trapped occupants to safety. Your initial size-up should determine whether they are in immediate danger or if they can wait while you attend to other more pressing life safety issues (photo 6).
Subways/Below-Grade Railroad Tracks. If your jurisdiction has a subway system or railroad tracks that are below grade level, escaping water can collect here, stalling trains and posing rescue challenges. Flooding in a subway could leave trains full of people stranded underground in hard-to-access tunnels, trapped by rising water. Determine in advance how to cut the power to the third rail and where you can obtain high-volume pumps to clear tunnels. The pumps will also be useful for clearing standing water from below-grade portions of a roadway and from individual buildings.
Steam Systems. If your area uses a high-pressure steam system to heat buildings or for industrial processes, a water main break could cause a destructive and deadly steam line rupture. The escaping water can rip the insulation off the underground steam pipes and cool and condense the steam inside the pipes, resulting in a catastrophic failure. Since high-pressure steam pipes were often insulated with asbestos, a steam main rupture could add asbestos contamination to your problems. A high-pressure steam main rupture will also confuse your communications because the sound from a ruptured steam pipe is similar to that of a ruptured high-pressure gas line.
|(6) Flowing water can affect several occupancies, posing risks to responding firefighters and any occupants unable to exit on their own. (Photo by Steve White.)|
Electric and Gas Services. Flooding in cellars and basements can damage the electric and the gas service of involved buildings, causing a loss of service and the danger of electric shock, fire, and explosion. Gas leaks may occur from water extinguishing gas appliance pilot lights or floating furnishings damaging gas pipes. The danger of electric shock from flooding is present without any obvious warning. When firefighters can do so safely, they should shut down gas and electric service to the flooded buildings; otherwise, they will have to wait for the utility to do so.
Heating Systems. Disabled heating systems will leave building occupants without heat or hot water for the duration of the incident and beyond as they await repairs. Flooding can damage gas heating units and result in gas leaks. Unsecured heating oil storage tanks may float in the rising floodwaters, and oil may leak from broken pipes. You would have to contact the oil supplier for cleanup.
Gas Mains. The flow of subsurface water may undermine gas mains near a water main as it washes away the soil supporting the main. An undermined main, especially if made of cast iron, can break from its own unsupported weight, resulting in a major gas leak. If water gets into the gas pipe, it will complicate the restoration of service. In addition, as the water undermines the pavement, the pavement will collapse into the void the flowing water creates and the collapsing pavement’s weigh may break a gas main (photo 7).
|(7) The powerful stream of water coming from the broken main will undermine the roadway and could damage the underground gas, electric, steam, and telephone lines. In addition, the nearby hydrants may be dry or underpressured as a result. (Photo by Lloyd Mitchell.)|
Gas leaking from a damaged gas main can migrate underground into the surrounding buildings, the sewer system, and the electric service manholes. Don’t forget that the gas odorant mercaptan can be scrubbed out of the gas as it passes through soil, so the absence of a gas odor does not mean there is no migrating gas in a building. Always use your gas meters to test the air in buildings and in sewer and electric manholes for the presence of natural gas. (See “Natural Gas Hazards” Fire Engineering, November 2004, 75-81, http://bit.ly/1J047iI.)
Arcing Manholes. Water entering an electric manhole or transformer vault can damage the equipment and initiate an underground electrical fire, which can spread to other manholes as well as buildings to which they are connected. The fire burning underground produces smoke with high concentrations of carbon monoxide and other toxic and explosive gases, which can migrate through the ground and the underground utility conduits into other manholes and buildings. If you have a manhole fire, monitor the surrounding buildings for carbon monoxide buildup.
Dislodged Manhole Covers. Anywhere along the flowing water’s route, the force of the water may dislodge the manhole covers for sewers, electric service, and other underground utilities. Like sinkholes, these open manholes under the flowing water could be invisible to the operating firefighters, especially at night. Firefighters should move cautiously when walking in the water. As with similarly obscured sinkholes, when firefighters need to enter the water, they should probe the path before them with their tools as they proceed.
Inoperable Hydrants. A broken main could disable hydrants over a large area, devastating our ability to fight any fires nearby. Test nearby hydrants and post “out of service” hydrant discs when necessary. Inform the units responding into this area of this condition and plan for an alternate water supply.
Icing Conditions. With freezing weather come slipping hazards during and after the incident is controlled, posing a risk to civilians and firefighters alike walking or driving in the affected area. Note the snow in photo 1. Arrange to have the area salted or sanded. For large areas, contact the appropriate agency-sanitation/public works department or a private contractor-to accomplish this.
Undermined Foundations. The water can undermine foundations, utility poles, and other elevated structures. If you suspect this is a possibility, evacuate the structure or area around the suspect utility pole, and set up an exclusion zone around them. Get an engineer to the scene as soon as possible to evaluate the hazard.
Water Diversion/Removal. Often, you may be able to prevent water from entering a building by wrapping a ladder in a tarp and laying it in on its side in front of an opening or by rolling up towels and stuffing them against a door. But the effectivness of these tactics depends on the building’s design and the amount of water present. Often, on arrival, it is too late to prevent the building from flooding. At the conclusion of the incident, you may have to pump out basements, roadways, or subway or train lines. Can your agency perform this service and still provide adequate fire protection? Beside the fire department, what agencies might supply pumps for this?
News Coverage. News agencies will show up at major incidents and want to speak to the incident commander. Initially, at least, he will likely be too busy to speak to them. Set up a safe staging area for them and assign someone to act as a public information officer to give them regular updates. If you give them information and photo opportunities, you can keep them happy and safe.
Medical Emergencies. A whole host of medical problems can affect firefighters and civilians. In addition to injuries directly related to the water-drowning or hypothermia-other likely injuries are possible. Falls causing cuts, bruises, or more serious injuries and conditions resulting from medical equipment failure, electric shock, and others injuries might require that medical assistance be available. It is prudent to have an ambulance standing by at a serious water main break.
Multiple Agencies. At first, the fire department will likely be the only agency on the scene, but that rapidly changes. Numerous other agencies may have to respond, depending on what the flooding is affecting: the water, gas, and electric utilities; the environmental protection agency and the hazmat team; the building, sanitation, and transportation departments; the police; the emergency medical services; and private contractors. Remember, this is a large water main gushing water into a heavily populated area. Coordinating these responding agencies’ actions and addressing their needs and demands may overwhelm the incident commander. He needs not only staffing but also management assistance. Call additional chief officers, delegate some of the tasks to them, and always keep your superiors aware of the scope of the incident. At the garbage truck sinkhole incident above, the many tasks involved quickly overwhelmed me, but it all got better quickly when my superior arrived and dealt with the various agencies while I dealt with the sinking truck.
Discuss the following questions with members of your department:
- If a large water main were to break in your response area, what issues are you likely to face?
- What possible solutions can you prepare before an incident occurs?
- What tools will you need? If you don’t have them already, get them.
- Are your firefighters aware of the inherent dangers present at these incidents? Explain and train on them.
- What agencies could be helpful to you? Contact them and set up protocols that will help when a main bursts. Otherwise, just sit back and hope you are not working when a main bursts or that you can deal with the emergency by winging it. Let me know how that works out for you.
FRANK MONTAGNA retired after 43 years with the Fire Department of New York (FDNY), where he served as a battalion chief for 26 years. He spent his final seven years assigned to the FDNY Training Academy, where he was responsible for curriculum and officer development and simulation training. He wrote the department’s gas and electric procedure manuals and is one of the creators of Fire Engineering‘s simulations. He has a bachelor’s degree in fire science and has taught courses for John Jay College based on his book Responding to Routine Emergencies, has published numerous fire-related articles, and lectures on these topics.