TACTICS FOR HAZ-MAT INCIDENTS

TACTICS FOR HAZ-MAT INCIDENTS

DISASTER MANAGEMENT

Part 5 in a series on managing chemical incidents.

THUS FAR IN OUR discussion of haz-mat incident management we’ve covered three of the seven steps in the GEDAPER process. Now that we’ve gathered vital data, estimated the incident course, and determined strategic goals, we must assess the tactical options and methods available to meet the strategies.

The relationship between strategic goals, tactical objectives, and tactical methods in a chemical incident are the same as their relationship in a “normal” fire situation: The strategic goal is what needs to be done, the tactical objective is how the goal will be met, and the tactical methods are resources needed to meet the objective.

TACTICS FOR ISOLATION

In executing the first strategic goal, isolation, we seek to minimize or eliminate the possibility of immediate exposure of responders and the public to the contaminant. A primary tactical objective to that end is the establishment of zones. One method for establishing zones is to assign an engine, truck, or haz-mat company to set a perimeter using ropes, highway cones, fire line tape, haz-mat tape, and the like and thus deny entry to the area. Immediately threatened persons can then be evacuated. The product is confined to the extent that physical tracking of the contaminant around the scene is controlled if not eliminated. The immediate incident scene is thereby isolated.

Some situations are so dangerous that withdrawal is the only appropriate approach for the entire operation. In such cases, evacuation of the area, establishment of zones, and denial of entry become absolutely vital to the safety of all concerned.

TACTICS FOR NOTIFICATION

Notification is a rather self-explanatory goal with regard to objectives and methods. However, several key steps can simplify notification.

First, it is very helpful to identify the incident response level, indicating the magnitude and severity of the incident. In the proposed NFFA Standard 471, three response levels are identified. (These response levels represent a general framework that can aid a department in establishing preplans for incidents of different magnitudes. Level 1 responses involve small containers such as pails or small packages and usually require simply a first-alarm assignment and a haz-mat team. No evacuation is necessary other than the immediate incident area, and leakage is small and easily dealt with, as with absorbents. Level I incidents do not pose a threat to life, and their impact on the environment is generally minimal. I-cvel II responses generally involve larger quantities of product in one-ton cylinders, large portable tanks, anil the like, but they are not massive quantities. This is a multiagency response that can extend beyond the local level. Leaks cannot be controlled without specialized Level A or 13 protective equipment. Level II responses can present a localized life threat and evacuation of a small number of people may be necessary. There may be some hazards to the environment. Level III responses are major incidents involving large quantities of product in containers such as tank cars, tank trucks, and large fixed tanks. Risks to health and environment are great, and a major evacuation and sheltering operation is probably imminent. State and federal agencies will most likely have to be notified.) By preplanning incident response levels, it is also possible to preplan general notification needs.

Second, identify agencies, groups, and individuals who may be needed at the incident. Maintaining a general catalog of parties can greatly ease the stress involved in notification and can eliminate the inadvertent omission of an important party. Some of the groupings that should be included are

1. local agencies—police, EMS, public health, public works, emergency management, water treatment, haz-mat coordinator;
2. local government&emdash;mayor, city/ town council, supervisors, municipal engineers;
3. utilities—phone, gas, electric;
4. local industry specialists;
5. local public and private groups— medical facilities, American Red Cross, the media, ham radio operators, aviation support, Salvation Army;
6. state agencies—environmental, highway, police, fire marshal, enforcement, public works, health;
7. national groups and agencies— CHEMTREC, National Response Center, EPA, Coast Guard.

TACTICS FOR IDENTIFICATION

The product(s) involved in the incident must be identified; that identification should then be verified. Depending on whether the incident is at a fixed facility or in a transportation setting, the exact method for achieving this goal will vary. Some of the methods for obtaining the information include translating placards and labels, taking statements from eyewitnesses, enlisting the aid of individuals educated in haz-mat analysis, and reading the shipping papers. For fixed facilities, specific preplan information, including material safety data sheets or inventories, should be available. More than one product identification source should be checked if possible to verify that an accurate identification has been made.

TACTICS FOR PROTECTION

Appropriate measures to protect personnel and the public must be taken. Some of the objectives toward meeting that goal include determining adequate levels of personal protective equipment (PFE), determining appropriate decontamination procedures for personnel and other contaminated individuals, determining appropriate population protection measures, and assuring that evacuation/shelter-in-place zones are of adequate size and distance.

Although it is simple to identify the tactical objectives of the protection strategy, determining the exact tactical methods are not. There are no clear-cut, straightforward answers. In many cases, the task of protecting human beings takes our technology and resources to their limits. Some situations are “losers,” in which the only proactive stance that an IC can take for protecting responders and the public is to isolate, identify, and notify. Sometimes, even with the latest, most sophisticated technology at our disposal, our best tactical method of accomplishing protection is withdrawal.

Personal Protective Equipment

The correct level of personal protective equipment (PPE) is a very complex issue. In-depth examination of many factors is required before appropriate methods can be determined. The importance of a thorough, in-depth examination to the safety of entry personnel can’t be overemphasized. The IC, safety officer, and haz-mat officer must thoroughly understand the specific incident and product factors and their implications. To do justice to this topic requires more space than is available in this article. However, some of the key factors that must be considered include the primary and secondary hazards of the product(s); • the primary and secondary hazards of the incident situation; • the types of PPE available; • the compatibility of PPE with the specific product involved; • the compatibility of PPE with the primary and secondary hazards of the product and the incident situation; • the specific activities to be performed by entry personnel; and • the type and degree of contamination that is likely to occur when personnel perform the activities.

Note that OSHA 1910.120 states that emergency response personnel exposed to substances “presenting an inhalation hazard or potential inhalation hazard shall wear positive-pressure, selfcontained breathing apparatus.” This level of respiratory protection must be maintained until the IC “determines through the use of air monitoring that a decreased level of respiratory protection will not result in hazardous exposures” for the responders involved. This means that responders must wear positive-pressure SCBAs during the entire emergency phase of the incident.

Decontamination

The determination of appropriate decontamination methods, unfortunately, is too often ignored. One of the primary reasons for this oversight is the complexity of the determination. Furthermore, many departments do not preplan for the specific resource needs and do not develop the standard operating procedures for decontamination methods. As a result, many personnel are put in the position of receiving chronic (repeated, possibly long-term) exposures to the contaminants left on their equipment. Such chronic exposures to low levels of a hazardous material can produce negative health impacts equal to or more severe than acute (single) exposure to a much higher level of the same product.

Some of the considerations for determining appropriate decontamination procedures are • the hazards and properties of the specific product(s) involved; • the specific activities performed by entry personnel; • the specific type of protective equipment that is worn; • the type of contamination; and • the degree of contamination.

There are many potentially disastrous misconceptions about decontamination. One of the most common is the belief that it’s all right to transport contaminated victims, personnel, and equipment prior to being decontaminated. Gross decontamination and packaging must occur on the incident scene. Contaminated victims must have contaminated clothing removed, undergo a thorough flushing, and be appropriately draped and covered (packaged) before they are transported.

Similarly, contaminated PPE and other equipment must be washed, rinsed, or neutralized (depending on the situation) and packaged in plastic bags, drums, or other containers at the incident scene. The packaged PPH and equipment must then be held for decontamination verification. Once personnel have removed the “decontaminated” equipment, they must at a minimum thoroughly wash their faces and hands and ideally change into some clean clothing. Then personnel can be transported to a station for a thorough shower.

If gross decontamination is not performed at the incident location, a trail of contamination will lead from the scene to the transport vehicle and on to the final destination. This trail of contamination may sound farfetched, but there are many documented instances in which medical and emergency room personnel have been overcome by contaminants brought in by transported, packaged victims. Consider all persons, equipment, and materials in contact with the contamination source as contaminated and requiring some type of decontamination.

All departments should be capable of peforming decontamination procedures, not just those with haz-mat teams. Departments in the northern areas are faced with the added problem of accomplishing gross decontamination in cold weather conditions and thus must provide sheltered, heated areas such as tents, commercially available decontamination structures, or specially designed vehicles.

Population Protection

The determination of appropriate population protection methods can also be a rather complex problem. The primary options are evacuation, shelteringin-place, or a combination of the two.

Most responders are very familiar with the concept of evacuation: getting people away from an area that poses a threat to their health and safety. Familiarity is one thing; accomplishing the task is another. Consider the following questions. Who has the authority to order an evacuation? In many jurisdictions, fire and police personnel can request an evacuation but cannot mandate one. In some locations, the only people who can declare an evacuation are emergency managers or even the state governors. How do we notify the people to leave? The use of door-todoor notifications, siren systems, and even the Emergency Broadcast System are often not very effective. How do we verify that people have in fact left? How long will it take to evacuate a given area? During rush hour? What are the best routes for evacuees to take? How are the evacuees notified of evacuation center locations? Will evacuating the public expose them to a toxic vapor or gas cloud? Remember, if responders need respiratory protection to perform an evacuation, the evacuees will also require the same protection.

The last point leads us to shelteringin-place. This is exactly what the name implies: The public is requested to remain within their buildings during the emergency. There, they are instructed to “button up,” that is, take measures to minimize the inflow of outside airclosing windows, shutting down air handling systems, shutting off air conditioners. Once the danger has passed, the public opens up the structures to maximize clean air entry into the “shelter” area.

Sheltering-in-place has been effective in some cases. Yet the call to shelter-inplace is rather difficult. The following considerations must be addressed: Is it inevitable that evacuees will be exposed to the cloud? How toxic is the cloud to which the public will be exposed? The higher the toxicity of the cloud, the more appropriate shelteringin-place may be. Is it feasible to evacuate the public in the first place? Consider high-rise structures in a metropolitan area. Is there time to evacuate people before the cloud reaches them? If it is going to take an hour to evacuate the public and a toxic cloud has moved in or will move in within 15 minutes, the more appropriate sheltering-in-place becomes. Is the release short-term or will it continue for an extended period? The longer the release will continue more than 30 to 60 minutes, the less appropriate sheltering-in-place becomes.

TACTICS FOR SPILL CONTROL

There are a host of tactical objectives and methods with which to meet our goal of controlling the spill. Choosing them relies on analysis of the spill element. In the third installation of this series, we established a matrix system that correlates the physical state of the product with the environmental media into which it is released. (See Fire Engineering, August ’89, page 90, Figure 1.)

Although there are 12 possible release types—gas, liquid, and solid as they each react with air, water, surface (any solid surface, regardless of porosity, location, and size), and subsurface (the soil underneath a surface)—several of them either mimic (act like) or transform (change) into one of four fundamental types of releases: gas/air, liquid/water, liquid/surface, and solid/ surface. Depending on the exact circumstances, two or more of these release types may be present during the hazardous chemical incident.

Once the IC has determined the specific type or types of release occurring, it is possible to identify the specific tactical options that are available. In each case there will be at least two or three possible tactical objectives and several methods to accomplish each objective.

Gas/Air

Gas/air releases (including vapor) are very common—probably the most common. They occur whenever gases, liquids, and, in some cases, solids escape their containers. Gases are the result of a material that is at or above its boiling point and/or critical temperature. Vapors, on the other hand, are the result of molecules of a liquid or solid that are forced from its surface and enter the atmosphere.

Once the molecules of gas or vapor have entered the air, the possible options available to handle the situation are identical. However, there are major differences in the options available to prevent release of a gas and a vapor into the air in the first place. To prevent gases from entering the air, some form of leak control activity must be employed; that is, the container and the breach must be addressed in some fashion. To prevent vapors from entering the air, control may be gained by addressing the liquid or solid material that is generating the vapor.

The most effective method of managing vapor production, short of preventing the release of the source product, is through blanketing. Blanketing is not a new concept to most firefighters. Firefighting foams have been used for many years in suppressing the vapors produced by flammable and combustible liquids. Yet, firefighting foam application is only one of the methods available to suppress vapor. Some of the other methods available to meet the objective of blanketing include: • stabilized foams that have basically unlimited 25 percent drain times; • haz-mat foams developed for use on specific types of acid or base spills; • plastic sheeting, salvage covers, and the like; and • sand and other inorganic materials.

Furthermore, absorbents—materials that literally attract and hold other materials to their surfaces—can be used in some situations. Activated charcoal, silica gel, and alumina are commonly utilized absorbents. Such “blankets” can effectively and efficiently control release of vapors into the air.

Once the vapor or gas has entered the atmosphere, identifying its degree of confinement is tantamount to deciding on the appropriate tactical objective. In other words, is the release into a confined space or into an exterior location? If the release is within an enclosed space, there is only one objective— ventilation. In some cases, ventilation should not commence until it has been determined that the release of the product into the air is in fact appropriate. In other cases, people may have to be evacuated from downwind locations prior to the ventilation. Air inlets for HVAC systems may have to be closed.

There are three possible tactical methods for accomplishing ventilation of an enclosed space: natural, mechanical, and hydraulic. Natural ventilation relies solely on natural air movement. It is most effective if the gas is lighter than air. Mechanical ventilation is accomplished by mechanical air-moving equipment such as a fixed HVAC or hood system or fire department smoke ejectors. Hood systems may be equipped with scrubber units that may remove or neutralize the contaminants. Using these mechanical devices to produce positive-pressure ventilation is generally most effective. Hydraulic ventilation relies on fog streams to draw the contaminated atmosphere from a structure. One of the primary drawbacks to the use of hydraulic ventilation is that the unmanned hoseline must first be positioned by personnel from inside the structure, possibly placing them in extreme danger.

If the gaseous product has been released into an exterior location, tactical options for spill control are rather different. Because there is no confinement, ventilation is not possible. This leaves the IC with: • diversion — changing the direction of movement; • dispersion — lowering the concentration by physically breaking up and scattering the product; • dissolution — lowering the concentration by dissolving the gas in some other media; and • neutralization — chemically changing the contaminant. The use of a fog stream is the primary method of achieving diversion, dispersion, and dissolution. The solubility of a product may result in contaminated runoff upon application of water, posing additional health and environmental hazards.

Determining the appropriate objective requires evaluation of the magnitude of the release and the waterreactivity and solubility of the product involved. In general, the greater the volume of the release, the lesser the likelihood of controlling the chemical release.

Liquid/Surface

Liquid/surface releases are probably the second most common type of chemical release. In this situation, a liquid is released and very rapidly contacts some surface (soil, pavement, tabletop, floor, etc.). Remember that whenever a liquid is released, there will be some degree of gas/air release because of the vapors produced. Several variables must be examined when assessing liquid/surface spills.

First, the IC must identify whether it is a membrane spill (less than 1/4 inch of product) or a depth spill (greater than 1/4 inch of product). Second, he must identify if the product is ongoing and estimate what the quantity of involved product may be. Third, he must identify any existing confinement systems such as dikes, retention ponds, retention tanks, and so on. Existing confinement measures dramatically simplify the situation. Fourth, he must identify the porosity of the surface involved. Generally, the more porous the surface, the more product it will absorb. Additionally, porous surfaces will usually help to minimize the total surface area of the spill.

After the IC has identified these variables it is then possible to determine the appropriate objectives. The possible tactical objectives available are

-diking—the placement of some type of physical barrier in front of an expanding spill;

-diversion—changing the direction of flow of the spill;

-containerization — holding the escaping product in some type of container, ranging from a bucket to a portapond to an excavated pit;

-absorption — drawing a material into the inner network of another material much as water is drawn into a sponge. This may do nothing to change the hazards of the contaminant;

adsorption—adherence of a liquid to the surface of another material. This may or may not affect the hazards of the contaminant;

neutralization—a chemical reaction utilized to reduce the degree of hazard presented by a product. In many situations, neutralization does nothing to stop the spread of product;

-gellation—changing a liquid into a gel. This may do nothing to change the hazards of the contaminant; and

solidification — changing a liquid into a solid. This may do nothing to change the hazards of the contaminant.

Liquid/Water

Liquid/water releases generally are not as common as liquid/surface or gas/ air releases. One reason for this is simply that there is much more land and air present than water. Yet in many locations, whenever a liquid/surface release occurs there is always the possibility that a liquid/water situation may evolve. Note that solid/water and watersoluble-gas/water releases either mimic or transform into liquid/water releases and should be handled similarly.

In general, liquid/water releases are difficult to handle because of the potential for product spread due to the movement of the water. As such, one of the variables to be considered by the IC is the body of water itself. What type of water body is involved —stream, pond, lake, river, bay, or ocean? What type of water movement is expected —primarily stagnant, normal stream, or tidal? How rapid is the movement of water? Is that movement turbulent or smoothflowing? How long and wide is the body of water?

The specific physical and chemical properties of the product are also vital considerations. Is the product watersoluble? Is the product lighter (less dense) or heavier (more dense) than water? Is it water-reactive? If the product is water-reactive, what are the properties of the resulting materials?

When these variables have been identified and assessed, the IC can determine the specific tactical objectives, including

• damming—a physical barrier to a body of water that stops the spread of the contaminant.
• booming—a floating physical barrier used to stop lighter-than-water contaminants.
• diversion — changing the direction of contaminant flow by using some type of physical barrier.
• absorption—a hydrophobic absor-
• bent material is usually placed on top of the water to absorb released contaminants.
• dispersion—a material that affects the surface tension of the contaminant, causing it to thin rapidly and spread over a body of water. Unless approval is gained from a federal on-scene coordinator, such a material should not be utilized. There are multiple options available in several of the objectives, depending primarily on the properties of the product. A closer examination is warranted.

Damming. The water-solubility and density of the product are the primary factors in determining which damming technique—complete, underflow, or overflow—is appropriate. Complete damming involves the complete stoppage of flow by constructing a dam. It is used when the product is water-soluble, thus threatening contamination of the entire body of water. Because complete damming means that all of the water and product are contained, it is only possible when the involved body of water is relatively small with a low flow rate.

Underflow damming involves only partial stoppage of flow. It is used when a product is not water-soluble and is lighter than water. The barrier is constructed with piping whose inlet end is placed lower in the body of water than its discharge end. Because the product is lighter than water, it floats on the surface and only relatively uncontaminated water from the bottom of the water column can flow through the dam.

Overflow damming also involves only partial stoppage of flow. It is used when a product is not water-soluble and is heavier than water. In this case a traditional dam barrier is built with some type of erosion-prevention barrier placed over the breast of the dam. Because the product is heavier than water, it sinks to the bottom and only relatively uncontaminated water flows over the breast.

Booming. Booms—containment or absorbent —float on the surface of the water. They are only effective for products that are not water-soluble and are lighter than water. Containment booms simply act as a physical barrier to the further spread of the contaminant; absorbent booms act as a barrier and also absorb the contaminant.

Diversion. Most commonly, this is used to direct a non-water-soluble, lighter-than-water product toward the bank of a stream or river. It normally requires the use of containment booms. Once the product has reached the bank, it can either be recovered or further diverted into a containment pond excavated into the bank.

There are a few cases in which diversion could be used for non-water-soluble, heavier-than-water products. However, this requires dredging the bottom of the channel to direct the product to some collection and recovery location.

Absorption. This involves the use of absorbent booms or pads. They must be hydrophobic (will not absorb water). The contaminants normally must be non-water-soluble and lighter than water. Very commonly, absorbent booms or pads are used in conjunction with containment booms or dams.

Solid/Surface

Solid/surface releases arc some of the least common releases encountered. In most instances, the easiest way to stop the spread of contaminants is to isolate the area and deny entry. However, depending on the properties of the contaminant, there may be major problems with weather conditions such as wind, rain, and humidity. A powdered solid easily may be blown by the wind, be dissolved by rain or snow, or react with the moisture in humid air. Blanketing is one of the best methods of addressing such problems. Normally plastic sheeting is appropriate for this purpose.

Next month we’ll continue our discussion of tactical objectives and methods and conclude with the final steps in the GEDAPER process for haz-mat incident management: plan and initiate actions, evaluate, and reevaluate.