Suppression Planning for Low-Bulk Density Fires

In a “Staff and Command” class at the New Jersey State Fire College in the mid-1980s, the instructor addressed us in an attempt at soothing our anxieties as prospective incident commanders: “Relax, the fire will go out eventually,” he said reassuredly. “Some you put out, and some run out of fuel, but they all go out.” But then he added, “Well, except the Jersey City Garbage Dump. That was burning my first day on the day job and has burned, popping up here and there, until recently when some experts from Texas put it out.”

This story still pops into my head when dealing with fires involving piles of mulch, wood chips, hay bales, industrial fluff, junk yards, garbage trucks or shredded documents. You will note that the title of this article is not simply “Suppression Planning for Fighting Fires” because that would suggest this is a routine fire problem. It is not.

When word comes that the fire has been knocked down, the new officer, confidence high, will almost always take the bait, as I did several times throughout my career, and start making certain declarations over the radio: “We have knockdown, cancel the balance of resources, and time of commitment will be less than an hour.”

When dealing with low-bulk density fires, however, one of two things usually happen following that call—we begin to slowly re-request resources, as we realize this fire simply isn’t going to go out, or we respond to a series of, dare I say it,  rekindles over the next few days. Either is unenviable, both disheartening.

A practical guideline for fighting these types of fires can be best summarized as S-W3 (Safety, Water, Wetting Agent, Work vs. Time). Because the materials discussed herein are very likely to be some form of waste or recyclable with little or no recoverable value, adjust your risk accordingly using the following S-W3 guidelines.

Safety

The safety concerns are bountiful. From collapse potential to hazardous energy to environmental factors, there are many factors to consider when fighting low-bulk density fires. Here is a quick look at some things to watch:

• Exposures—Will the fire, if unchecked, threaten exposures? Have they been evacuated and protected? 
• Look Up, Look Down and Look All Around—Look up and live is regular dialogue for wildland fire crews across the country because it’s effective. A 360-degree situational awareness check, especially after the flames go down and adrenaline fades, must be maintained. 
• Dust Explosion Potential—The materials discussed in this article are larger particles than could generate a flammable dust explosion. Careful consideration must be given to wetting and aeration of dust-type fuels to avoid explosive conditions. 
• Collapse—As we are doing our jobs, these materials will inevitably get heavier with water. Overhead piles or containers holding the material may be subject to collapse or failure. 
• Lock Out, Tag Out—It is crucial to control hazardous energy, such as machinery and utilities. Machinery—conveyors, grinders, compactors and overhead cranes—should be shutdown, verified and secured. Utilities such as buried or overhead wires should be identified and shutdown to avoid electrocution and breach of pipeline hazards. Verify with AC current detectors and knowledgeable facility personnel, if present.
• Dumpster Fire Analogy—The materials may contain waste materials. If you would fight a dumpster fire with SCBA (and I hope you would), then do it here. Let it burn out if the risk is too great.  
• Voids—Wildland firefighters know too well the possibility of falling into a stump hole burning below the surface of cool ash. Avoid traversing these materials, which can swallow whole excavators. Use stream reach in support of excavators or heavy equipment.
• Environmental—Environmental factors, including smoke, heat, decontamination and weather, must be taken into consideration. Low-lying smoke due to suppression and inversions can shut down area schools, hospitals, hotels, etc., as well as require SCBA over large areas as the hot zone expands. Consider source materials like wind, weather and measurable indicator gasses to help manage smoke. Our PPE ensembles, coupled with hard, long-duration work, will likely aggravate the potential for heat illnesses. Rotate crews often with good rehab and scale back PPE and tactics to fit the hazard. As the concerns with occupational disease due to exposure of fire and post-fire products are a focus of our community, plan to conduct a gross decontamination in the field and follow decon and extraction policies for all PPE when in quarters. Less exposure is best. By the time you get the memo that the materials you were covered in are hazardous, it might be too late. And always keep an eye on the weather. Flare-ups typically occur as the sun travels over the site and the relative humidity lowers. Smoke will get worse with inversions and cooler weather. Flow path discussions have taught us that weather is not just for wildland firefighting anymore.
• Working with Heavy Equipment—Wildland firefighters know working the “big yellow Pulaski” is productive but dangerous. You will very likely need heavy equipment in your plan. Simply put, give these machines a wide berth, stay out of their blind spots, don’t work downhill from them on material piles, and always make eye contact and signal the operator before you approach the stopped machine.  
• Master Streams—Master streams provide reach where firefighters cannot safely access, and they also provide high volumes of water. We also know that these can be dangerous, so have a spotter in contact with the operator.
• Flooding—High volumes of water runoff, which you will likely need, can flood your original position. Continually evaluate whether you are being effective in coordination with work and wetting agents to minimize runoff. Plan to move to higher ground after initial knockdown.
• Establish Scene Control—Use the hazmat models if needed when establishing scene control. Anyone in the Hot Zone must wear SCBA and be in full PPE. Full accountability must be maintained.

Water

Water, of course, is the most important aspect of fighting low-bulk density fires. You will need a lot of water and you will need to manage it correctly. Here are some tips on water use:

• Volume—You will need lots of water. The materials found in low-bulk density fires are what are known as “resistant to control,” which will require copious amounts of water, ranging from small garden hoses doing mop up to master streams as discussed previously.
• Coordination—Coordinate water delivery with overhaul work. Once you have knockdown, you only need small flows to maintain the smolder phase with flows adjusted upward as materials are exposed and flare ups begin. For fires in containers, filling the whole space with water may be necessary.  
• Duration—Set up for the long haul. Know that whatever hose and engines you commit may be there for days until replaced by the contract equipment suggested below.
• Reuse—Reuse or use static sources if possible. Potable water is expensive, but out West, it’s worth fighting over. During four days of fighting two large document storage warehouse fires (one which was a total loss), our county depleted a town’s potable water supply to near-crisis levels. After the neighboring town refused to open the connection valve, we reconfigured to draft from retention ponds that were filled to the brim with three days of runoff. It’s OK to employ used water once the hazard is verified.
• Burn Throughs—Monitor your hoselines if they cross over materials. An area that looks extinguished can flare or smolder through your hoselines, causing damage and leaving you high and dry. Keep a few spare rolls on scene for replacement.   

Wetting Agent

Wetting agents can be just as important as water. Here are a few:

• Foam Efficacy—Foam merchants have oversold the benefits of foam and wetting agents in many applications, causing a bit of rejection and a convenient excuse for those who are inclined not to maintain foam equipment. While benefits of Class A foam are arguable in our circles regarding the initial attack and knockdown, there is no question as to its efficacy in overhaul, mop up and expanding water supply. The most expensive aspect of any ground-based suppression operation is the one who wears a helmet. The work of the firefighter is greatly enhanced by foam and wetting agents. We owe efficiency to the taxpayer as well as our memberships. With regard to knockdown and initial attack, it’s like chicken soup for a cold; it’s not prescription, but it couldn’t hurt.
• Foam Blankets—Foam blankets were part of the oversell of Class A foams in the late-1990s. It is generally accepted the drain-down time of a highly aerated (blanket) Class A foam is about 10 minutes on vertical or three-dimensional surfaces. These materials have a large surface area-to-mass ratio—in other words, lots of nooks and crannies to fill with foam and that can provide conduits for oxygen defeating any smothering effort. As these fires can span acres, it’s unlikely you would be able to apply a perfectly sealed foam blanket in time to smother a fire like that used on a flammable liquid storage tank. Laying down foam without the support of hard work is better than just water, but largely a waste.
• Environmental Limits—Class A foam is far more environmentally friendly than its early Class B cousin. However, the introduction of foams and wetting agents through runoff to surface or groundwater can introduce chemical components that increase chemical or biological oxygen demand, which in turn impact fish and aquatic species. Some wildland firefighting agencies prohibit use of foams and wetting agents within 100 feet of a water body. Check your Safety Data Sheet and consult with regulatory agencies for advice when your runoff is not contained. 
• Foam Systems—There are plenty of foam systems of varying complexity and costs from which to choose. Whichever you choose understand their limits and maintenance requirements. Most importantly, match the eductor or injection system to the flows desired and nozzle or applicator. In the absence of a foam system, batch mixing in portable tanks or tenders should be considered. Your pumps can handle this foam solution. Be careful to watch tank gauges as the foam solution can aerate as it enters a tender or booster tank and give a false full reading on the tank gauge even after that water is getting low. Fresh water flushes of pumps and plumbing involved will be required. Foam in various dilutions can be carried by personnel in spray or condiment squirt bottles for application on a small scale for hot spots.
• Foam Concentrations—Typical Class A applications are from 0.1 percent to 1.0 percent. More is not always better. Start at 0.5 percent and adjust within this range for effect and economy. The desired effect is water absorbing into the materials, not necessarily bubbles. In the context of Class A foam, having the water absorb into the fuels converting BTUs to steam is what is desired. The bubbles or aeration help keep the water on a three-dimensional or vertical surface and increase the chances of absorption, but also reduce, not totally eliminate contact with air.

Work vs. Time

Low-bulk density fires take a lot of work and a lot of time. Keeping a balance between the two is key. Here are some tips:

• Think Horsepower—If it took a bulldozer to put it there, it will certainly take one to move it around. Various sources place a unit of horsepower (hp) equivalent to the work of 3–10 men in short bursts. A NWCG Type 2 Wildland Bulldozer (medium) ranges from 100 hp to 200 hp. The low end is equivalent to approximately 300–1,000 persons assisting you. Think about that when you are in wet turnouts on your second hour with a trash hook. Get either the responsible party or your Office of Emergency Management to get you heavy equipment early on in the incident if your department doesn’t have these available. The operators may need to be trained to operate with SCBA or have Hazardous Waste Operations and Emergency Response (HAZWOPER) training. Some useful types may be a bulldozer with grapple or ripper, an excavator or track hoe with various buckets and thumbs, a front-end loader, and a skidder.
• Material Handling—Wet materials will be harder to move around as they become heavier. Plan your approach logically as not to impede your progress with your success. Set up a grid or wind-row pattern to turn over the materials. I have seen stump and mulch piles several stories high with fire deep within; you will need to have a place to put materials.
• Pumps and Water Equipment—You may get to the point where you need your hose and engines back. Like heavy equipment, pumps and waterways can be rented or contracted within a few days. All of these things get easier if you plan for it.  Be sure to use pressure-relieved fire apparatus  
• Rekindle Potential—Expect and plan for the rekindle. Be the very last to believe the fire is really most sincerely out. Remain diligent with patrols and fire watch.
• Fire Watch and Patrol—Establish a fire watch with the intent to transition to patrol as you begin to demobilize the scene. You will need to leave a crew for fire watch behind. Leave or reposition hose lays to support the patrols as you will likely have hot spots flare up. Have the crew keep a log. As periods of time go by without a rekindle or TIC hit, switch to patrol at intervals less than the fire watch observations of flare-ups in order to transition off the incident. Be conservative.
• Thermal Imaging Cameras (TIC)—Much of my experience with this suppression challenge preceded TIC technology. Use of TICs will prove invaluable, but require follow up as in structure fires. During a recent experience, a TIC was used that yielded helpful targeting of non-visual hot spots. This tool enhanced our hard work and reduced duration; however, both remained significant. In researching how better to use the TIC in this application, subject-matter experts have placed an emphasis on using spot temperature readings as well understanding that the mass of wetted materials may be masking hot spots. TIC technology has a wide range of continuously evolving applications, each with its advantages and limitations. Check with your TIC manufacturer on how best to use it in this application

In sum

Plan on using the S-W3 Model for the long haul on low-bulk density fires. The battle will be with time and logistics after knockdown. This is one of the least glamorous firefighting tasks, but often represents a long period of operation and draws on resources relative to a residential structure fire. These type of target hazards don’t hide easily as they can be quite large. Identify the materials, create a preplan involving site management that includes the resources and tactics discussed herein, and those operation periods may be a little more bearable. 

RUSSELL KANE began his fire service career in 1981 as a volunteer firefighter in Monroe Township, NJ. He progressed through the ranks of the volunteer fire service, holding various line and staff officer positions and, ultimately, department chief. Upon transition of his volunteer unit to a career organization, Kane served as a shift commander and safety officer from 1999 to 2005. After obtaining his bachelor’s degree from Rutgers University in 1989, Kane went to work in the New Jersey Chemical Industry, serving as an industrial fire chief and environmental and safety engineer until 2001. Kane also served from 1990 to 2002 in local and county emergency management roles as a hazardous materials coordinator and assistant fire bureau chief, respectively. He served active operations and plans section roles in various regional Type 1–3 Incidents as well as the county’s response to the World Trade Center attacks. Kane also served with the New Jersey State Police’s NJ Task Force #1 Urban Search and Rescue Team as a hazmat/WMD specialist from 2001 to 2007. In 2005, he earned his master’s degree in public safety management from St. Joseph’s University. In 2005, Kane began service with NorthTree Fire International as deputy operations chief, providing clients of federal and state governments as well the Union Pacific Railroad with fire suppression, hazmat, training, planning and technical rescue services. In 2008, Kane began service with the California Department of Forestry & Fire Protection (CAL FIRE) as a fire captain serving with multiple field units, training and regional staff positions, ultimately promoting to the rank of battalion chief. He is a credentialed emergency service instructor and has been on the faculty of several training academies and organizations across the country. Kane is presently serving as the deputy chief of the Cimarron Hills Fire Department in Colorado Springs, CO.