HAZ-MAT RESPONDS TO LEAKING BATTERY ACID
BY PETER M. STUEBE
Recently, the City of New York (NY) Fire Department responded to a report of a truck fire in an industrial area in the East New York section of Brooklyn. Fire companies in this area are among the busiest in the city, with most responding to more than 5,000 alarms a year. Due to the large volume of commercial traffic in this area, a truck fire report is a common occurrence. On arrival, however, it was immediately obvious to the responding units that this was not going to be any routine operation. The truck was a flatbed tractor-trailer loaded with hundreds of used car and truck batteries that were burning and leaking sulfuric acid onto the street.
The first-arriving officer immediately announced his arrival at the scene and called for the response of a battalion chief and the fire department`s hazardous-materials response team, Hazardous Materials Company 1. Because of Haz Mat 1`s 20- to 30-minute response time to that section of Brooklyn, the incident commander (IC) asked for instructions from Haz Mat 1 on what to do pending their arrival. We advised the IC that the fire was not due to the battery acid, since sulfuric acid is not flammable. The fire`s fuel was probably the plastic battery casings, which are considered ordinary combustibles and normally would be extinguished with water. However, because of the reaction generated when water is added to an acid, Haz Mat 1 advised that the fire be extinguished not with water but with dry chemical extinguishers. Additionally, the caustic nature of the dry chemical would neutralize some of the leaking acid. We also advised the IC that any acid spilled on the street should be diked and prevented from entering the sewer system. This could be performed while wearing standard bunker gear and SCBA, if the responders were able to do so without coming in contact with the product. This is FDNY standard operating procedure when doing so will not put firefighters in danger.
ASSESSING THE HAZ-MAT SITE
When Haz Mat 1 arrived, the IC briefed us, and we reassessed the situation. The truck was a 40-foot-long flatbed, containing hundreds of scrap batteries on pallets, and each pallet was shrink-wrapped to hold the batteries together. On one of the pallets, batteries were still burning, since the first-due units had expended their supply of dry chemical without completely extinguishing the fire. Battery acid, which is 30 percent sulfuric acid, was leaking from the flatbed onto the street, but the truck company had diked the spill, preventing further spread. We theorized that the fire started when the cables of adjoining batteries touched, which caused sparking and the igniting of surrounding casings. Batteries transported as scrap should have their cables removed to prevent such an occurrence. In this case, not all the cables had been removed.
After gathering our information, we then discussed various plans of action. Our first priority was to extinguish the remaining fire, since this would also prevent additional acid from leaking out. Since sulfuric acid is nonflammable, the fire`s fuel consisted of the battery casings, the shrink wrap, and the wooden pallets. Water would have been effective on the fire. However, when water is added to sulfuric acid, the resulting dilution reaction is strongly exothermic, causing splattering and generating considerable heat. Additionally, sulfuric acid is soluble in water, as are corrosives in general. Any water used in extinguishment would violently mix with the acid, increasing the amount of liquid that would have to be confined, neutralized, and disposed of. This course of action had the potential to cause injury and was ruled out.
EXTINGUISHING THE FIRE
We selected dry chemical as the extinguishing agent, since it would do the job without any reaction with the acid and Haz Mat 1 had enough on hand to extinguish the remaining fire completely.
Knowing the skin-contact hazard that sulfuric acid poses, we carefully considered which form of personal protective equipment (PPE) to use. Since the remaining fire could be extinguished without coming in close proximity to the acid, bunker gear and SCBA were deemed adequate. With their mission established, the entry team dressed in full bunker gear and proceeded to extinguish the remaining pockets of fire. Throughout the operation, we had to watch continually for additional fires starting, since the potential for cables touching and reigniting the fire was a constant danger.
With the fire extinguished, the next problem was the acid in the street, which was still leaking from the fire-damaged batteries. We would have to off-load the batteries down to the street, then dump out the remaining acid. This would take some time and would involve firefighters coming in contact with the acid, probably getting splashed with it. Because of the skin contact hazard, we decided to use an encapsulating liquid/splash protective suit, with SCBA worn on the inside of the suit. This ensemble is commonly referred to as “Level B” protection. A check of the suit compatibility charts shows this suit to be compatible with the challenge chemical. Also, sulfuric acid has a low vapor pressure (
REMOVING THE BATTERIES
Off-loading and draining the damaged batteries took several hours. We estimated that at least 150 batteries had to be off- loaded, emptied, and then stacked for later removal. To perform such an arduous task, we rotated three two-member teams. Each member spent about 30 minutes working and then was removed. On completing each entry, the teams had to be decontaminated. Because corrosives are water-soluble, a simple detergent and water solution was used. All of our chemical protective clothing is disposable, which simplifies the decon process.
RECOVERING THE SPILLED ACID
The next segment of the incident involved the spilled and diked acid. Testing with pH paper showed a pH of 1, confirming a very strong acid. For small corrosive spills, of one gallon or less, diluting with water and flushing may be an acceptable solution. However, it takes a large amount of water to dilute most corrosives to a point at which they can be discarded safely. Unless a large volume of water is used, dilution will not reduce the strength of such a strong acid significantly. Neutralization, another option at corrosive spills, is frequently performed by many haz-mat teams. However, we ruled out this course of action for several reasons. Haz Mat 1 does not carry a large enough supply of soda ash (sodium carbonate) to neutralize such a large spill. Also, the New York City Department of Environmental Protection (DEP) prefers not to flush hazardous materials into the sewer system, even if neutralized. Neutralizing a chemical does not necessarily render it safe. Thus, even with additional neutralizer available, this option was ruled out.
The preferred method for dealing with such a spill in New York City is to remove the product, either for reuse or proper disposal. Haz Mat 1 carries several different types of pumps for transferring liquids and also various sizes of overpack drums. The drums have a sprayed-on coating to prevent corrosion of the metal, and we also place a plastic liner in the drum for added safety. With the inner liner in the drum, we pumped the acid off the street using an air-powered pump. The total amount recovered was about 100 gallons, contained in two 55-gallon drums.
At such an operation, even with the most conscientious recovery efforts, a certain amount of product residue will remain. At this point, we neutralized the sulfuric acid residue with a solution of soda ash and water. This procedure must be done carefully, due to the high pH of this caustic neutralizing solution. Much training, practice, and experience are necessary to do this successfully, ensuring that the pH is not carried past neutral, thus creating a caustic spill.
On successfully neutralizing the residual acid, the DEP representative allowed us to flush this small amount of residue into the sewer system. Since the owners of the batteries were responsible for the acid, they agreed to hire an outside contractor to remove the two drums. The DEP, which is responsible for ensuring that such products are removed safely, supervised the operation. The batteries` owner also sent a crew to recover the burned batteries. When the remaining batteries on the truck were secured, fire department units were able to leave the scene.
In any operation, even those that go fairly smoothly, a critique is an important learning tool. Participants can discuss what went right, why it went right, and what went wrong.
Detail sufficient personnel for the operation. We should have had more personnel available to perform such a strenuous task. Six members worked in rotation for several hours to accomplish the job. Also, when wearing chemical-protective clothing, personnel must be watched closely for signs of heat stress, and those so affected must be removed and allowed to recover sufficiently before going back to work. Having more personnel to assist will vastly reduce the chance for a heat- or fatigue-related injury. Since this operation, several other companies in New York City have been trained to operate as backup haz-mat companies. Thus, personnel is no longer a problem.
Eliminate unnecessary effort. Off-loading the batteries by hand to the street and then dumping them was not the most efficient disposal procedure. We should have emptied each battery into a lined 55-gallon drum as it was handed down from the truck. This would have saved considerable effort.
Secure an adequate supply of neutralizer. Haz Mat 1 carries about 50 pounds of soda ash, which has in the past has been sufficient for most incidents. However, we have had incidents requiring a truckload of soda ash, but we have a limit on what we can carry. While recovery is the preferred method of mitigating a corrosive spill, a situation could arise in which additional neutralizer will be required. We therefore identified several additional supply sources. The DEP stocks neutralizer, as does Con Edison, New York City`s utility company. Con Ed in particular stockpiles various neutralizing agents in many of its facilities around the city. Having this information before it is needed may prove very helpful for future incidents and should be a part of preincident planning for all fire departments. n
DILUTION AND NEUTRALIZATION
In New York City, the official position of the Department of Environmental Protection (DEP) is that hazardous-materials spills should be recovered and properly disposed of whenever possible. However, there can be situations in which other courses of action are appropriate. When a spill involves corrosives, two options that can also be considered are dilution and neutralization.
Dilution through the addition of water reduces the concentration of a corrosive material to a nonhazardous or less hazardous state. The material being diluted must be soluble in water, or dilution will not occur. Although usually easily accomplished, dilution tactics often are not the best course of action. Dilution is typically used for very small spills, one gallon or less. Consider the following points.
Certain acids are water-reactive (e.g., oleum). Although water fog streams may be applied to knock down and control large corrosive vapor clouds, water must not come in contact with the product.
You can pour acid into water, but never pour water into acid. When water contacts a water-reactive corrosive, it may cause a violent reaction, heat generation, vapor production, and container overpressurization.
Dilution requires large amounts of water. It is not a straight, linear, one-to-one process but is actually a logarithmic process (one-to-10 scale). For example, to lower the pH of one gallon of acid from one to three would require approximately 1,000 gallons of water. The net result of dilution usually is a larger spill that may create more environmental problems for responders. It therefore usually is not a realistic tactical option.
Without sufficient quantities of water, the result may be just a larger quantity of material that must still be mitigated and properly disposed of.
The pH scale runs from one to 14, where one is a strong acid, seven is neutral, and 14 is a strong base. Neutralization adjusts the pH of corrosives, moving the pH closer to seven, which is neutral, like water (neither acid nor base). It is an exothermic chemical reaction usually resulting in the creation of water, a salt, heat (which may be considerable), and carbon dioxide (which could lead to excessive pressure buildup if not properly vented).
Acids, which have a pH below seven, are neutralized by carefully adding a caustic, or base, solution. (In FDNY, common soda ash is used.) Prepackaged, commercial neutralizers are also available from haz-mat equipment suppliers. Generally, a slurry solution is created by adding the soda ash to water and then carefully applying the slurry solution to the acidic spill until the pH is changed to a safer level.
Conversely, an acidic solution is added to a base or caustic spill to neutralize it. (Bases have a pH above seven.) However, when dealing with chemical facilities with their own wastewater treatment plant, simply changing the pH of an acid from two to five may be sufficient so that the neutralized spill can now be safely handled through the wastewater process.
A common problem with neutralization is that too much neutralizer is added, pushing the pH too far in the other direction (i.e., the original acid spill now becomes a caustic spill). In facilities where acid spills are a possibility, neutralizers such as sodium carbonate (soda ash) and sodium bicarbonate are often kept on the premises. Sodium bicarbonate forms a weak base in water, minimizing the potential for pushing the pH too far and changing an acid spill into a caustic spill. Also, because it is a weak base, it is safer to handle than the stronger bases.
Even when neutralized, some materials may still have hazardous characteristics. Knowledge of the released material and its neutralization byproducts is essential to safely mitigate an incident. Access to product specialists is often critical. Properly done, neutralization can make cleanup safer, easier, and less expensive, but it requires a significant amount of knowledge and training before it can be done safely and effectively. n
PETER M. STUEBE is an 18-year veteran of the City of New York (NY) Fire Department, the captain of Haz-Mat Company 1, a member of the Westchester County (NY) Hazardous Materials Response Team, and previously was a hazardous-materials instructor at the FDNY Bureau of Training. He has a bachelor`s degree in business from Marist College, has a master`s degree in economics from Pace University, and is currently working on a master of public health degree in environmental science at Columbia University.