The round rubber hazmat — tire fires


CarolinaFireJournal - By David Greene
By David Greene
10/05/2012 -

This issue we will be examining scrap and shredded tire fires by using the United States Fire Administration’s (USFA) Technical Report Series # 093, published in December 1998. The United States disposes of approximately 240 million tires annually. Seventy-five percent of these are added to existing stockpiled tire dumps or discarded in landfills. Burying tires in landfills has become the least desirable option as the casings trap air and buried tires often move. 

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This interferes with reclaiming future landfills. There have been attempts at recycling tires for use as retreads, crash barriers, artificial reefs, road resurfacing and fuel. However, the technological problems with recycling tires have not yet been fully overcome.

Rubber tires are composed of several very combustible compounds such as carbon, oil, benzene, toluene, rubber and sulfur. As a result, tires have a higher per-pound heat output than most coal. Tires are also designed to absorb friction-generated heat from road contact. However, once ignition occurs, this same property serves to absorb the heat of the fire. This is apparent to anyone who has knocked down the flames of a tire fire only to find it has reignited shortly after moving the fire stream away. Tires also give off flammable vapors at approximately 1000 degrees Fahrenheit. According to the USFA, there is also approximately 55,000 gallons of unburned run-off oil for every million tires burned. By comparison, it is estimated that one passenger car tire can produce a little more than two gallons of oil. Moreover, there are at least 32 toxic gases produced by tire fires.

The ability to control a large tire pile fire is extremely time sensitive. This makes the response and initial operations time compressed. From ignition to the first five minutes after ignition, extinguishment may be possible if the fire is small enough for available water supplies. However, after the first few minutes, fire will spread approximately two square feet every five minutes. After the first 30 minutes, the top layers of the burning pile will begin to collapse to the interior. Much like a coal pile, visible flaming will be reduced. The fire will then be deep seated and covered by a clay-like ash crust. After approximately an hour of burning, the crust will be capable of protecting the burning core from water stream penetration. The continuing downward pressure will cause run-off oil flow to increase dramatically.

Operationally, a fire in a large tire pile can be extinguished if the first-in engine arrives within a few minutes of ignition and has an adequate water supply to cover the area involved. Class A foam can be used to aid with these smaller fires. After the first few minutes, the only option is to attempt to separate the unburned tires from the fire. This is difficult and many may find is also not a rapid option. After the first 30 minutes, fuel separation may be the only option. It is also important to contain run-off from this point forward. Large caliber streams will only add to the run off problem. After an hour of burning, the only way to reach the seat of the fire is to break through the top layer crust using heavy equipment. It is important to note that the crust may very well adhere to the heavy equipment. This is also a crossroads between emergency responders and industrial workers. Personal protective equipment (PPE) and self-contained breathing apparatus (SCBA) may be required during the heavy equipment operation. The Incident Commander may be forced to quickly educate firefighters in the use of heavy equipment or industrial workers in the use of PPE and SCBA. Keep in mind that much of the heavy equipment necessary for sustained operations requires skilled operators.

The USFA examined seven case studies from Garfield County, Washington; Washington, Pennsylvania; Cearfoss, Maryland; Chautaugua County, New York; Frankfort, Kentucky; District of Columbia; and Gila River Indian Reservation, Arizona. Each case study reviewed fires involving bulk storage of tires.

The Washington State case resulted in $3 million in clean up costs. The Pennsylvania case involved 1.7 million tires stacked 50 feet high. The fire burned for 14 days, required the evacuation of 500 residents, and closed two schools. Most of these case studies had several commonalities aside from the extended operations required for mitigation and excessive costs for recovery. First, the bulk of the departments handling these emergencies found the use of Class B foams ineffective. Class B foam cannot create the film that separates the fuel from the oxygen. Air entrainment can typically be achieved from under and within the pile which makes oxygen exclusion on the surface of the pile ineffective. Additionally, the cooling properties of Class B foams cannot reach the seat of the fire which is located beneath both the top layer crust and the exterior fuels. Second, surface extinguishment with water was not achievable in any of the cases reviewed. Third, the bulk of the facilities at which these fires occurred lacked pre-incident surveys. Finally, while the Maryland fire was extinguished in 12 hours, the Washington state fire began on February 16, 1996 and was not fully extinguished until the last week of June 1996 (five months later). This is a prime example of the resource commitment necessary based on the fuel load present.

As in most things we do, proper planning is necessary for these types of incidents. This should include identifying and completing pre-incident surveys on any bulk storage facilities in our jurisdictions. If personnel report that someone is storing large numbers of tires at a facility, being prepared is essential. It may also give us an opportunity to reduce the chances of an incident through code enforcement. NFPA 231D “Standard for Storage of Rubber Tires” can be used for code enforcement purposes. Specifically, Appendix C requires fire lanes for access, proper clearances from exposures, and a 60 foot wide separation between piles or an earthen berm one and one-half times the height of the pile. Additionally, the maximum pile size cannot be greater than 20 feet in height and 250 feet in length and width. Eliminating natural ground fuels in the vicinity is also important. The pre-incident survey should also contain contact numbers for heavy equipment operators who can assist in fuel isolation and separation.

Operationally, there are not many options when dealing with a large tire pile fire. The first option is non-intervention or simply to let the fire burn. Keep in mind that large amounts of water applied to tire fires can accelerate the rate at which run-off oil contaminates the surrounding environment. Allowing the fire to burn can also reduce the impact on air pollution. Once the fire reaches the equilibrium and pyrolysis stage (after approximately one hour), most of the fuel will be consumed and the toxic products of combustion will be decreased. These products include benzene, toluene, chrysene, zinc oxide, titanium dioxide, carbon monoxide, sulfur dioxide and hydrogen sulfide. Fixed air monitoring around the property will be a necessary activity throughout the course of the incident, but particularly when non-intervention is selected as the operating mode. If it is small enough, it may be possible to bury the fire using dirt. Remember that dirt is the best extinguishing agent in the world (and is readily available). It’s just a shame it doesn’t stick to anything. In every case, water and Class B foams were ineffective. Keep in mind that the oil produced during burning may be a Class B fuel but tires themselves are rubber, a Class A fuel. There is some debate if Class A foams are effective but in any case are only appropriate for smaller sized fires. Again, if extinguishment is selected as a tactic, you should plan for extensive overhaul utilizing heavy equipment. Hand lines may be needed to protect heavy equipment during overhaul. Controlling run off is paramount at any incident such as this but is particularly important if water streams are being utilized

In Winchester, Virginia, a nine million-tire fire produced approximately 500,000 gallons of run-off oil, only half of which was recovered. Dikes, dams, and retention ponds may be necessary during extended operations. Class B foams may be necessary for any burning run-off oil. Finally, someone needs to find the checkbook. Operations of this type have an average cost of $45,000 per day. Reimbursement from the property owner may not be possible and typically maximum federal reimbursements for hazardous materials incidents will only cover the costs of about one-half of a day.

Don’t forget that this incident will require a massive amount of command and control. The IC will need to be supported by a highly skilled and effective command staff. The Safety Officer will have their hands full making sure everyone is properly protected and the heavy equipment doesn’t become part of the fire. The Liaison officer is critical to interact with the multiple mutual aid, state and federal agencies that may be involved. There should also be a highly skilled Public Information Officer. This individual may have to explain to the public via the media why the fire department thinks not putting water on the fire is the best course of action. Given the time span involved, the incident may require multiple redundancies of each position. The Washington state fire spanned over 300 operational periods. There is certainly no IC or even an incident command team that can effectively manage a fire for five months, 24 hours a day. The Operations Section will be busy with public protective actions (i.e. evacuations), fire suppression, hazardous materials confinement, air monitoring and personnel accountability. The Logistics Section will have their hands full with resource support. Planning will be overwhelmed by site safety plans, long term cleanup strategies, incident documentation and the eventual demobilization of the incident resources. Finance will also be inundated with procurement of contractors and special equipment, coordination of local, state, and federal expenses, incident accounting and cost recoupment efforts.

Bulk tire storage facilities are being seen everywhere. It is difficult to know if and where these types of hazards exist within your jurisdiction. Given the amount of time, resources and money involved, it is essential to identify and plan on responses to these incidents. Code enforcement should be used to minimize the chances of an incident occurring. Code enforcement can also limit the size of incidents such as these, should they occur. We should also be adding heavy equipment and mutual aid agencies to our resource lists for these types of incidents. Remember, no single agency can effectively manage a major hazardous materials incident. When pulling up to a large tire pile fire, you should be phoning your friends for help and planning for an extended stay.

Be safe and do good.

David Greene has over 20 years experience in the fire service and is currently the Assistant Chief with Colleton County (SC) Fire-Rescue. He is currently working on his PhD through Oklahoma State University. He is a certified Executive Fire Officer through the National Fire Academy, holds the Chief Fire Officer Designation and is an adjunct instructor for the South Carolina Fire Academy. He can be reached at [email protected].
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