Posts Tagged ‘firefighter injury’

My last post, Hazards Above, provided a brief overview of three incidents involving extreme fire behavior in the attic or truss loft void spaces of wood frame dwellings. This post will examine the similarities and differences between these lessons and identify several important considerations when dealing with fires occurring in or extending to void spaces. At the conclusion of Hazards Above, I posed five questions:

1. What is similar about these incidents and what is different?
2. Based on the limited information currently available, what phenomena do you think occurred in each of the cases? What leads you to this conclusion?
3. What indicators might have pointed to the potential for extreme fire behavior in each of these incidents?
4. How might building construction have influenced fire dynamics and potential for extreme fire behavior in these incidents?
5. What hazards are presented by fires in attics/truss lofts and what tactics may be safe and effective to mitigate those hazards?

Similarities and Differences

The most obvious similarities between these incidents was that the buildings were of wood frame construction, the fire involved or extended to an attic or truss loft void space, and that some type of extreme fire behavior occurred. In two of the incidents firefighters were seriously injured, while in the other firefighters escaped unharmed.

Given the limited information available from news reports and photos taken after the occurrence of the extreme fire behavior events, it is not possible to definitively identify what types of phenomena were involved in these three incidents. However, it is interesting to speculate and consider what conditions and phenomena could have been involved. It might be useful to examine each of these incidents individually and then to return to examine fire behavior indicators, construction, and hazards presented by these types of incidents.

Minneapolis, MN

In the Minneapolis incident the fire occurred in an older home with legacy construction and relatively small void spaces behind the knee walls and above the ceiling on Floor 3. The triggering event for the occurrence of extreme fire behavior is reported to be opening one of the knee walls on Floor 3. As illustrated in Figure 1, the fire appeared to transition quickly to a growth stage fire (evidenced by the dark smoke and bi-directional air track from the windows on Floor 3 Side A. However blast effects on the structure are not visible in the photo and were not reported.

Figure 1. Minneapolis MN Incident: Conditions on Side A

Note: Photo by Steve Skar

Potential Influencing Factors: While detail on this specific incident is limited, it is likely that the fire burning behind the knee wall was ventilation controlled and increased ventilation resulting from opening the void space resulted in an increase in heat release rate (HRR). Potential exists for any compartment fire that progresses beyond the incipient stage to become ventilation controlled. This is particularly true when the fire is burning in a void space.

Extreme Fire Behavior: While statements by the fire department indicate that opening the knee wall resulted in occurrence of flashover, this is only one possibility. As discussed in The Hazard of Ventilation Controlled Fires and Fuel and Ventilation, increasing ventilation to a ventilation controlled fire will result in increased HRR. Increased HRR can result in a backdraft (if sufficient concentration of gas phase fuel is present), a vent induced flashover, or simply fire gas ignition (such as rollover or a flash fire) without transition to a fully developed fire.

Harrisonburg, VA

The Harrisonburg incident involved extreme fire behavior in Exposure D (not the original fire unit). The extreme fire behavior occurred after members had opened the ceiling to check for extension. However, this may or may not have been the precipitating event. As illustrated in Figure 2, as members prepare to exit from the windows on Floor 3 , Side C, flames are visible on the exterior at the gable, but it appears that combustion is limited to the vinyl siding and soffit covering. There are no indicators of a significant fire in Exposure D at the time that the photo was taken. However, it is important to remember that this is a snapshot of conditions at one point in time from a single perspective.

Figure 2. Harrisonburg, VA Incident: Conditions on Side C

Note: Photo by Allen Litten

Potential Influencing Factors: The truss loft was likely divided between units by a 1 hour fire separation (generally constructed of gypsum board over the wood trusses). While providing a limited barrier to fire and smoke spread, it does not generally provide a complete barrier and smoke infiltration is likely. Sufficient smoke accumulation remote from the original fire location can present risk of a smoke explosion (see NIOSH Report 98-03 regarding a smoke explosion in Durango, Colorado restaurant). Alternately, fire extension into the truss loft above an exposure unit can result in ventilation controlled fire conditions, resulting in increased HRR if the void is opened (from above or below).

Extreme Fire Behavior: Smoke, air track, and flame indicators on Side C indicate that the fire in the truss loft may not have continued to develop past the initial ignition of accumulated smoke (fuel). It is possible that smoke accumulated in the truss loft above Exposure B and was ignited by subsequent extension from the fire unit. Depending on the fuel (smoke)/air mixture when flames extended into the space above Exposure B ignition could have resulted in a smoke explosion or a less violent fire gas ignition such as a flash fire.

Sandwich, MA

In the Sandwich incident, the extreme fire behavior occurred shortly after the hose team applied water to the soffit. However, this may or may not have been the precipitating event. As illustrated in Figure 3, the fire transitioned to a fully developed fire (likely due to the delay in suppression as the injured members were cared for). Blast effects on the structure are obvious.

Figure 3: Sandwich, MA: Conditions on Sides C and D

Note: Photos by Britt Crosby (http://www.capecodfd.com)

Potential Influencing Factors: The roof support system in this home appears to have been constructed of larger dimensional lumber (rather than lightweight truss construction). In addition, it is likely that the attic void spaces involved in this incident were large and complex (given the size of the dwelling and complex roof line). It appears that at least part of the home had a cathedral ceiling. Fire burning in the wood framing around the metal chimney would have allowed smoke (fuel) and hot gases to collect in the attic void in advance of fire extension.

Extreme Fire Behavior: The violence of the explosion (see blast damage to the roof on Side D in Figure 3) points to the potential for ignition of pre-mixed fuel (smoke) and air, resulting in a smoke explosion. However, it is also possible that failure of an interior ceiling (due to water or steam production from water applied through the soffit) could have increased ventilation to a ventilation controlled fire burning in the attic, resulting in a backdraft).

Fire Behavior Indicators

The information provided in news reports points to limited indication of potential for extreme fire behavior. One important question for each of us is how we can recognize this potential, even when indicators are subtle or even absent.

Important! A growth stage fire can present significant smoke and air track indicators, with increasing thickness (optical density), darkening color, and increasing velocity of smoke discharge. However, as discussed in The Hazard of Ventilation Controlled Fires, when the fire becomes ventilation controlled, indicators can diminish to the point where the fire appears to be in the incipient stage. This change in smoke and air track indicators was consistently observed during the full-scale fire tests of the influence of ventilation on fires in single-family homes conducted by UL earlier this year.

Even with an opening into another compartment or to the exterior of the building, a compartment fire can become ventilation controlled. Consider building factors including potential for fire and smoke extension into void spaces in assessing fire conditions and potential for extreme fire behavior. A ventilation controlled fire or flammable mixture of smoke and air may be present in a void space with limited indication from the exterior or even when working inside the structure.

Building Construction

Each of these incidents occurred in a wood frame structure. However, the construction in each case was somewhat different.

In Minneapolis, the house was likely balloon frame construction with full dimension lumber. As with many other structures with a “half-story”, the space under the pitched roof is framed out with knee walls to provide finished space. This design is not unique to legacy construction and may also be found with room-in-attic trusses. The void space behind the knee wall provides a significant avenue for fire spread. When involved in fire, opening this void space can quickly change fire conditions on the top floor as air reaches the (likely ventilation controlled) fire.

The incident in Harrisonburg involved a fire in a townhouse with the extreme fire behavior phenomena occurring in an exposure. While not reported, it is extremely likely that the roof support system was comprised of lightweight wood trusses. In addition, there was a reverse gable (possibly on Sides A and C) that provided an additional void. As previously indicated, the truss loft between dwelling units is typically separated by a one-hour rated draft stop. Unlike a fire wall, draft stops do not penetrate the roof and may be compromised by penetrations (after final, pre-occupancy inspection). Installed to code, draft stops slow fire spread, but may not fully stop the spread of smoke (fuel) into the truss lofts above exposures.

Firefighters in Sandwich were faced with a fire in an extremely large, wood frame dwelling. While the roof appeared to be supported by large dimensional lumber, it is likely that there were large void spaces as a result of the complex roofline. In addition, the framed out space around the metal chimney provided an avenue for fire and smoke spread from the lower level of the home to the attic void space.

Hazards and Tactics

Forewarned is forearmed! Awareness of the potential for rapid fire development when opening void spaces is critical. Given this threat, do not open the void unless you have a hoseline in hand (not just nearby).

Indirect attack can be an effective tactic for fires in void spaces. This can be accomplished by making a limited opening and applying water from a combination nozzle or using a piercing nozzle (which further limits introduction of air into the void).

If there are hot gases overhead, cool them before pulling the ceiling or opening walls when fire may be in void spaces. Pulses of water fog not only cool the hot gases, but also act as thermal ballast; reducing the potential for ignition should flames extend from the void when it is opened.

Lastly, react immediately and appropriately when faced with worsening fire conditions. Review my previous posts on Battle Drill (Part 1, Part 2, and Part 3). An immediate tactical withdrawal under the protection of a hoseline is generally safer than emergency window egress (particularly when ladders have not yet been placed to the window).

Ed Hartin, MS, EFO, MIFireE, CFO

Finally! It has been quite some time since my last post, but the CFBT-US web site and blog have been attacked twice by hackers WordPress and ISP upgrade issues have been a major challenge and it has taken some time to get things back to normal.

A Big Improvement, But More Work is Needed

The Fire Service in the United States saw a considerable reduction in firefighter line-of-duty deaths in 2009. However, our efforts to improve firefighter safety must persist. Recent events reinforce the need to ensure understanding of practical fire dynamics and have the ability to apply this understanding on the fireground.

Three recent incidents involving extreme fire behavior present an opportunity to examine and reflect on the hazards presented by fires and accumulation of excess pyrolizate and unburned products of combustion in attics and other void spaces.

Minneapolis, MN Residential Fire

At 1130 hours on Saturday, July 3, 2010 Minneapolis firefighters responded to a residential fire at 1082 17th Avenue SE. First arriving companies observed light smoke and flames showing from a two and one-half story wood-frame home. A crew opening up the kneewall on the A/D corner of Floor 3 was trapped on the third floor by rapid fire progress.

Note: Photo by Steve Skar

A department spokesperson indicated that as they opened up the walls “it flashed over on them”. News reports indicated that the blast threw Firefighter Jacob LaFerriere, across the room and that he was able to locate a window, where he exited and dropped to the porch roof, one floor below. Capt. Dennis Mack was able to retreat into the stairwell where he was assisted to the exterior by other crews operating on the fireground (Mathews, 2010; Radomski & Theisen, 2010).

News reports also reported that a witness stated that the “flashover was quite loud and within seconds heavy fire was venting from the attic area” (Mathews, 2010). A later statements by department spokespersons indicated introduction of oxygen when the wall was opened resulted in the flashover (Porter, 2010) and that a burst of flames blew out the south side of the roof (Radomski & Theisen, 2010).

Firefighter Jacob LaFerriere suffered third degree burns on his arms and upper body. Capt. Dennis Mack suffered second degree burns (Radomski & Theisen, 2010) and are as of Sunday, July 4 were in satisfactory condition in the Hennepin County Medical Center Burn Unit.

Harrisonburg, VA Townhouse Fire

On June 24, 2010 Harrisonburg, Virginia firefighters responded to an apartment fire off Chestnut Ridge Drive. First arriving companies encountered a fire in a townhouse style, wood frame apartment. Investigating possible extension into Exposure Bravo, Firefighters Chad Smith and Bradly Clark observed smoke and then flames in the attic. They called for a hoseline, but when the pulled the ceiling, conditions worsened as the room ignited. Both firefighters escaped through a second floor window (head first, onto ladders placed by exterior crews). Four other firefighters were inside Exposure B when the extreme fire behavior occurred. Two received second degree burns, one was treated for heat exhaustion, and the fourth was uninjured (Firehouse.com News, 2010; WHSV, 2020). Department spokespersons indicated that a backdraft occurred when fire gases built up in the attic.

Note: Photo by Allen Litten

Sandwich MA Residential Fire

At around noon on Memorial Day, Sandwich, Massachusetts firefighters responded to a residential fire at 15 Open Trail Road. On arrival they found a 5,000 ft² (464 m²) wood frame single-family dwelling with a fire on Side C (exterior) with extension into the home. Firefighters Daniel Keane and Lee Burrill stretched a handline through the door on Side A, knocking down the fire and extending the line out onto a deck on Side C. Fire was extending through a void containing a metal chimney flue on the exterior of the building. The crew on the hoseline was making good progress until they hit the soffit with a straight stream and an explosion occurred. The force of the blast knocked the crew over the deck railing and caused significant structural damage. Firefighter Keane suffered fractures of his neck and back while Firefighter Burrill experienced a severely fractured ankle (Fraser, 2010; D LeBlanc personal communication June 2010).

Note: Photos by Britt Crosby (http://www.capecodfd.com/)

Questions

One of these fires occurred in an older home of legacy construction, the other two occurred in relatively new buildings. One was a large contemporary home, likely with an open floor plan and large attic/trussloft voids. The other two occurred in buildings with smaller void spaces in the attic/trussloft.

1. What is similar about these incidents and what is different?
2. Based on the limited information currently available, what phenomena do you think occurred in each of the cases? What leads you to this conclusion?
3. What indicators might have pointed to the potential for extreme fire behavior in each of these incidents?
4. How might building construction have influenced fire dynamics and potential for extreme fire behavior in these incidents?
5. What hazards are presented by fires in attics/trusslofts and what tactics may be safe and effective to mitigate those hazards?

Late Breaking Information

Two firefighters and an officer from the Wharton Fire Department were trapped by rapid fire progress in a commercial fire at the Maxim Production Company in Boling, TX on July 3, 2010. The crew had advanced a hoseline into the 35,000 ft² (3252 m²) egg processing plant to cut off fire extension when they encountered rapidly worsening fire conditions. The two firefighters were able to escape, but Captain Thomas Araguz III was trapped and killed (Statter, D., 2010). More information will be provided on this incident as it becomes available.

References

Mathews, P. (2010). Two Minn. ffs burned in flashover. Retrieved July 4, 2010 from http://www.firehouse.com/news/top-headlines/two-minneapolis-firefighters-burned-flashover

Radomski, L & Theisen, S. (2010). Firefighters hospitalized after flashover identified. Retrieved July 4, 2010 from http://kstp.com/news/stories/S1637495.shtml?cat=1

Porter, K. (2010). 2 firefighters burned in Mpls. fire ID’d. Retrieved July 5, 2010 from http://www.kare11.com/news/news_article.aspx?storyid=856556&catid=396

WHSV. (2010) Harrisonburg firefighters talk about their close call. Retrieved July 5, 2010 from http://www.whsv.com/home/headlines/97127924.html

Firehouse.com News. (2010). Harrisonburg, Va. firefighters forced to bail out. Retrieved July 5, 2010 from http://www.firehouse.com/showcase/photostory/harrisburg-va-firefighters-have-bail-out

Fraser, D. (2010). Mass. firefighters thrown more than 30 Ft. by blast. Retrieved July 5, 2010 from http://www.firehouse.com/news/top-headlines/blast-throws-mass-firefighters-more-30-feet

Statter, D. (2010). Update: Captain Thomas Araguz III killed during 4-alarm fire at egg plant in Boling, Texas. http://statter911.com/2010/07/04/firefighter-killed-during-4-alarm-fire-at-egg-plant-details-from-wharton-county-texas/

Quick Review

The previous post in this series presented a video clip of an incident on the afternoon of February 18, 2010 that injured four Chicago firefighters during operations at a residential fire at 4855 S. Paulina Street.

First arriving companies discovered a fire in the basement of a 1-1/2 story, wood frame, single family dwelling and initiated fire attack and horizontal ventilation of the floors above the fire. Based on news accounts, the company assigned to fire attack was in the stairwell and another firefighter was performing horizontal ventilation of the floors above the fire on Side C when a backdraft or smoke explosion occurred. Two firefighters on the interior, on at the doorway and the firefighter on the ladder on Side C were injured and were transported to local hospitals for burns and possible airway injuries.

In analyzing the video clip shot from inside a nearby building, we have several advantages over the firefighters involved in this incident.

Time: We are not under pressure to make a decision or take action.

Reduced Cognitive Workload: Unlike the firefighters who needed to not only read the fire, but also to attend to their assigned tactics and tasks, our only focus is analysis of the fire behavior indicators to determine what (if any) clues to the potential for extreme fire behavior may have been present.

Repetition: Real life does not have time outs or instant replay. However, our analysis of the video can take advantage of our ability to pause, and replay key segments, or the entire clip as necessary.

Perspective: Since the field of view in the video clip is limited by the window and the fidelity of the recording is less than that seen in real life, it presents a considerably different field of view than that of the firefighters observed in operation and does not allow observation of fire behavior indicators and tactical operations on Sides A, B, and D.

Initial Size-Up

What B-SAHF indicators could be observed on Side C up to the point where firefighters began to force entry and ventilate the basement (approximately 02:05)?

Figure 1. Conditions at 01:57 Minutes Elapsed Time in the Video Clip

Building: The structure is a 1-1/2 story, wood frame, dwelling with a daylight basement. The apparent age of the structure makes balloon frame construction likely, and the half story on the second floor is likely to have knee walls, resulting in significant void spaces on either side and a smaller void space above the ceiling on Floor 2. One window to the left of the door on Side C appears to be covered with plywood (or similar material). Given the location of the door (and door on Side A illustrated in the previous post in this series), it is likely that the stairway to the basement is just inside the door in Side C and a stairway to Floor 2 is just inside the door on Side A.

Smoke: A moderate volume of dark gray smoke is visible from the Basement windows and windows and door on Floor 1 as well as a larger volume from above the roofline on Side B. While dark, smoke on Side C does not appear to be thick (optically dense), possibly due to limited volume and concentration while smoke above the roofline on Side B appears to be thicker. However smoke on Side C thickens as time progresses, particularly in the area of the door on Floor 1. The buoyancy of smoke is somewhat variable with low buoyancy on Side C and greater buoyancy on Side B. However, smoke from the area of the door on Floor 1 Side C intermittently has increased buoyancy.

Air Track: Smoke on Side C appears to have a faintly pulsing air track with low velocity which is masked to some extent by the effects of the wind (swirling smoke due to changes in low level wind conditions). Smoke rising above the roofline on Side B appears to be moving with slightly greater velocity (likely due to buoyancy).

Heat: The only significant heat indicators are limited velocity of smoke discharge and variations in buoyancy of smoke visible from Sides B and C. Low velocity smoke discharge and low buoyancy of the smoke on Side C points to relatively low temperatures inside the building. The greater buoyancy and velocity of smoke observed above the roofline on Side B indicates a higher temperature in the area from where this smoke is discharging (likely a basement window on Side B).

Flame: No flames are visible.

Initial Fire Behavior Prediction

Based on assessment of conditions to this point, what stage(s) of development and burning regime(s) is the fire likely to be in?

Dark smoke with a pulsing air track points to a ventilation controlled, decay stage fire.

What conditions would you expect to find inside the building?

Floors 1 and 2 are likely to be fully smoke logged (ceiling to floor) with fairly low temperature. The basement is likely to have a higher temperature, but is also likely to be fully smoke logged with limited flaming combustion.

How would you expect the fire to develop over the next few minutes?

As ventilation is increased (tactical ventilation and entry for fire control), the fire in the basement will likely remain ventilation controlled, but will return to the growth stage as the heat release rate increases. Smoke thickness and level (to floor level) along with a pulsing air track points to potential for some type of ventilation induced extreme fire behavior such as ventilation induced flashover (most likely) or backdraft (less likely). Another possibility, would be a smoke explosion; ignition of premixed gas phase fuel (smoke) and air that is within its flammable range (less likely than some type of ventilation induced extreme fire behavior)

Ongoing Assessment

What indicators could be observed while the firefighter was forcing entry and ventilating the daylight basement on Side C (02:05-02:49)?

There are few changes to the fire behavior indicators during this segment of the video. Building, Heat, and Flame indicators are essentially unchanged. Smoke above the roofline appears to lighten (at least briefly) and smoke on Side C continues to show limited buoyancy with a slightly pulsing air track at the first floor doorway.

What B-SAHF indicators can be observed at the door on Side C prior to forced entry (02:49-03:13)?

Figure 2. Conditions at 03:06 Minutes Elapsed Time in the Video Clip

Figure 3. Conditions at 03:08 Minutes Elapsed Time in the Video Clip

Building, Smoke, Heat and Flame indicators remain the same, but several more pulsations (03:05-03:13) providing a continuing, and more significant indication of ventilation controlled, decay stage fire conditions.

What indicators can be observed at the door while the firefighter attempts to remove the covering over the window adjacent to the door on Floor 1 (03:13-13:44)?

No significant change in Building, Heat, or Flame Indicators. However, smoke from the doorway has darkened considerably and there is a pronounced pulsation as the firefighter on the ladder climbs to Floor 2 (03:26). It is important to note that some of the smoke movement observed in the video clip is fire induced, but that exterior movement is also significantly influenced by wind.

What B-SHAF indicators do you observe at the window on Floor 2 prior to breaking the glass (03:44)?

Figure 4. Conditions at 03:43 Minutes Elapsed Time in the Video Clip

The window on Floor 2 is intact and appears to be tight as there is no smoke visible on the exterior. It is difficult to tell due to the angle from which the video was shot (and reflection from daylight), but it would be likely that the firefighter on the ladder could observe condensed pyrolizate on the window and smoke logging on Floor 2. It is interesting to note limited smoke discharge from the top of the door and window on Floor 1 in the brief period immediately prior to breaking the window on Floor 2.

What indicators are observed at the window on Floor 2 immediately after breaking the glass (03:44-03:55)?

Figure 5. Conditions at 03:52 Minutes Elapsed Time in the Video Clip

No significant changes in Building, Heat, or Flame indicators. Dark gray smoke with no buoyancy issues from the window on Floor 2 with low to moderate velocity immediately after the window is broken.

What B-SAHF indicators were present after the ventilation of the window on Floor 2 Side C was completed and 04:08 in the video clip (03:44-04:08)?

Buoyancy and velocity both increase and a slight pulsing air track develops within approximately 10 seconds. In addition, the air track at the door on Floor 1 shifts from predominantly outward with slight pulsations to predominantly inward, but with continued pulsation (possibly due to the limited size of the window opening on Floor 2, Side C.

Anticipating Potential Fire Behavior

Unlike the firefighters in Chicago who were operating at this incident, we can hit the pause button and consider the indicators observed to this point. Think about what fire behavior indicators are present (and also consider those that are not!).

Initial observations indicated a ventilation controlled decay stage fire and predicted fire behavior is an increase in heat release rate with potential for some type of extreme fire behavior. Possibilities include ventilation induced flashover (most likely) or backdraft (less likely), or smoke explosion (less likely than some type of ventilation induced extreme fire behavior).

Take a minute to review the indicators of ventilation controlled, decay stage fires as illustrated in Table 1.

Table 1. Key Fire Behavior Indicators-Ventilation Controlled, Decay Stage Fires

Which of these indicators were present on Side C of 4855 S. Paulina Street?

Building: The building appeared to be unremarkable, a typical single family dwelling. However, most residential structures have more than enough of a fuel load to develop the conditions necessary for a variety of extreme fire behavior phenomena.

Smoke: The dark smoke with increasing thickness (optical density) is a reasonably good indicator of ventilation controlled conditions (particularly when combined with air track indicators). Lack of buoyancy indicated fairly low temperature smoke, which could be an indicator of incipient or decay stage conditions or simply distance from the origin of the fire. However, combined with smoke color, thickness, and air track indicators, this lack of buoyancy at all levels on Side C is likely an indicator of dropping temperature under decay stage conditions. This conclusion is reinforced by the increase in buoyancy after ventilation of the window on Floor 2 (increased ventilation precipitated increased heat release rate and increasing temperature).

Air Track: Pulsing air track, while at times quite subtle and masked by swirling smoke as a result of wind, is one of the strongest indications of ventilation controlled decay stage conditions. While often associated with backdraft, this indicator may also be present prior to development of a sufficient concentration of gas phase fuel (smoke) to result in a backdraft.

Heat: Velocity of smoke discharge (air track) and buoyancy (smoke) are the only two heat indicators visible in this video clip. As discussed in conjunction with smoke indicators, low velocity and initial lack of buoyancy which increases after ventilation is indicative of ventilation controlled, decay stage conditions.

Flame: Lack of visible flame is often associated with ventilation controlled decay and backdraft conditions. However, there are a number of incidents in which flames were visible prior to occurrence of a backdraft (in another compartment within the structure). Lack of flames must be considered in conjunction with the rest of the fire behavior indicators. In this incident, lack of visible flames may be related to the stage of fire development, but more likely is a result of the location of the fire, as there is no indication that flames were present on Side C prior to the start of the video clip.

What Happened?

Firefighters had entered the building for fire attack while as illustrated in the video clip, others were ventilating windows on Side C. It is difficult to determine from the video if a window or door at the basement level on Side C was opened, but efforts were made to do so. A window on Floor 2 had been opened and firefighters were in the process of removing the covering (plywood) from a window immediately adjacent to the door on Floor 1. At 04:12, an explosion occurred, injuring two firefighters on the interior as well as the two firefighters engaged in ventilation operations on Side C.

Starting at approximately 03:59, velocity of smoke discharge from the window on Floor 2 Side C increases dramatically. At 04:08 discharge of smoke begins to form a spherical pattern as discharged from the window. This pattern becomes more pronounced as the sphere of smoke is pushed away from the window by increasing velocity of smoke discharge at 04:12, immediately prior to the explosion. Velocity of smoke discharge at the door increases between 03:59 and -4:12 as well, but as the opening is larger, this change is less noticeable. As pressure increases rapidly during the explosion a whooshing sound can be heard. After the explosion, there was no noticeable increase in fire growth.

Figure 6. Conditions at 04:08 Minutes Elapsed Time in the Video Clip

Figure 7. Conditions at 04:09 Minutes Elapsed Time in the Video Clip

Figure 8. Conditions at 04:10 Minutes Elapsed Time in the Video Clip

Figure 9. Conditions at 04:11 Minutes Elapsed Time in the Video Clip

Figure 10. Conditions at 04:12 Minutes Elapsed Time in the Video Clip

Figure 11. Conditions at 04:13 Minutes Elapsed Time in the Video Clip

Based on observation of fire behavior indicators visible in the video clip, we know that a transient extreme fire behavior event occurred while a crew was advancing a hoseline on the interior and ventilation operations were being conducted on Side C. What we don�t know is what firefighting operations were occurring on the other sides of the building or in the interior. In addition, we do not have substantive information from the fire investigation that occurred after the fire was extinguished.

The Ontology of Extreme Fire Behavior presented in an earlier post classifies these types of phenomena on the basis of outcome and conditions. As a transient and explosive event, this was likely a backdraft or smoke explosion. In that this occurred following entry and during ongoing ventilation operations, I am inclined to suspect that it was a backdraft.

Indicators visible on Side C provided a subtle warning of potential for some type of ventilation induced extreme fire behavior, but were likely not substantially different from conditions observed at many fires where extreme fire behavior did not occur.

As the title of the wildland firefighting course S133 states; Look Up, Look Down, Look Around! Anticipation of fire development and extreme fire behavior requires not only recognition of key indicators, but that these indicators be viewed from a holistic perspective. Firefighters and/or officers performing a single task or tactical assignment may only see part of the picture. It is essential that key indicators be communicated to allow a more complete picture of what is occurring and what may occur as incident operations progress.

Ed Hartin, MS, EFO, MIFireE, CFO

Updated March 7, 2010 with Longer Video Clip of this Incident

On the afternoon of February 18, 2010, firefighters in Chicago responded to a residential fire at 4855 S. Paulina Street. First arriving companies discovered a fire in the basement of a 1-1/2 story, wood frame, single family dwelling and initiated fire attack and horizontal ventilation of the floors above the fire.

Based on news accounts, the company assigned to fire attack was in the stairwell and another firefighter was performing horizontal ventilation of the floors above the fire on Side C when a backdraft or smoke explosion occurred. Three firefighters on the interior and the firefighter on the ladder on Side C were injured and were transported to local hospitals for burns and possible airway injuries.

Figure 1. Consider Key Fire Behavior Indicators

B-SAHF Indicators

Recognizing subtle fire behavior indicators during incident operations can be difficult and important indicators are often only visible from one location (other than where you are). What Building, Smoke, Heat, and Flame (B-SAHF) indicators would you anticipate seeing if potential backdraft conditions exist (or may develop as the incident progresses)? How would this differ from the indicators that conditions may present risk of a smoke explosion?

For more information on key fire behavior indicators related to ventilation controlled burning regime, decay stage fires, backdraft, and smoke explosion, see the following posts:

• Recent Extreme Fire Behavior
• Decay Stage Fires: Key Fire Behavior Indicators
• Real �Backdraft�
• Hazard of Ventilation Controlled Fires
• Smoke Explosion or Backdraft?
• Language & Understanding: Extreme Fire Behavior
• 15 Years Ago: Backdraft at 62 Watts Street
• 62 Watts Street: Modeling the Backdraft
• Extreme Fire Behavior: An Organizational Scheme (Ontology)
• Fires and Explosions
• Gas Explosions
• Gas Explosions Part 2
• Extreme Fire Behavior: An Organizational Scheme
• Fuel and Ventilation

Incident Video

A video of the incident at 4855 S. Paulina Street was recently posted on YouTube (a shorter version is posted on Firevideo.net). It appears that the video may have been shot through a window by an occupant of the D2 exposure. The title of this video is �Chicago Smoke Explosion�. After watching the video and answering the questions posed in this post, do you think that this was a backdraft or smoke explosion? Why?

One of the great assets of using video as a learning tool is the ability to stop the action and go back to review key information. Watch the video and stop the action as necessary to answer the following questions�

• Pause at 02:05. What B-SAHF indicators could be observed on Side C up to this point in the video clip?
• Pause at 02:49. What indicators could be observed while the firefighter was forcing entry and ventilating the daylight basement on Side C?
• Pause at 03:13. What B-SAHF indicators can be observed at the door on Side C prior to forced entry?
• Pause at 03:35. What indicators can be observed at the door after forcing the outer door (prior to ventilation of the window on Floor 2)?
• Pause at 03:44. What B-SHAF indicators do you observe at the window on Floor 2 prior to breaking the glass?
• Pause at 03:55. What indicators are observed at the window on Floor 2 immediately after breaking the glass?
• Pause at 04:08. What B-SAHF indicators were present after the ventilation of the window on Floor 2 Side C was completed and 04:08 in the video clip?

After answering the questions, watch the complete clip. Do you think that this was a backdraft or smoke explosion? If you thought that this was a backdraft: Did you see potential indicators? If so what were they? If not, why do you think that this was the case? If you think that this was a smoke explosion, what indications lead you to this conclusion? What indicators were present?

You may want to watch this video clip several times and give some thought to what factors were influencing the B-SAHF indicators (particularly smoke, air track, and heat). Were these indicators consistent with your perception of backdraft indicators? Is so, how? If not, what was different? What indicators may have been visible from other vantage points. Remember that the video provides a view from a single perspective (and one that is considerably different than the crews working at this incident).

The next post in this series will take a closer look at the video and key fire behavior indicators.

Ed Hartin, MS, EFO, MIFireE, CFO

The Problem

NIOSH has investigated a number of incidents in which firefighters trapped by rapid fire progress did not take appropriate survival action. Last September, I was reading NIOSH Report F2007-02, which outlined the circumstances surrounding the death of Firefighter Steven Solomon in Atlanta, Georgia. Firefighter Solomon was severely burned after being caught by rapid fire development while advancing an attack line in a vacant structure (see Figure 1).

Figure 1. Rapid Fire Development

Note: Atlanta Fire Department photo from NIOSH Report F2007-02

Firefighter Solomon was on the nozzle as the first arriving truck removed the plywood covering the front door and thick, black smoke came rolling out the top of the doorway. Firefighter Solomon and the crew of Engine 16 advanced the line into the building as the truck continued horizontal ventilation. After advancing a short distance, fire conditions quickly worsened and the crew attempted to back out, but collided with another company who was advancing a backup line. After exiting the building the crew of Engine 16 realized that Firefighter Solomon was still inside. Crews outside the door on Side A observed the silhouette of a firefighter running through the flames inside the building.

As I read the report, I asked myself how a firefighter on a hoseline that was just a short distance could have been killed by rapid fire development. The NIOSH report identified four contributing factors:

• Initial size-up not conducted.
• Failure to recognize the signs of an impending flashover/flameover.
• Inadequate communication on the fireground.
• Possibility of ventilation induced rapid fire progression.

While these factors likely contributed to Firefighter Solomon�s death, I still did not have a solid answer to my question of how a firefighter on a hoseline just a short distance inside the doorway could have died in this type of event.

Predictability

The best way to avoid being injured or killed in an extreme fire behavior event is to read the fire, anticipate likely fire behavior, and control your operating environment. A majority of our effort should be spent on mastering these skills.

There is no unpredictable fire behavior. Under the same conditions, a compartment fire will develop and behave consistently. However, conditions are not always the same! In addition, firefighters operate with limited information, imperfect skill in anticipating likely fire behavior, and often under pressure to take rapid action. When making decisions under pressure, in a complex and dynamic environment, and with limited information, potential for error increases.

Improved understanding of fire dynamics and development of a high level of skill reduces, but does not eliminate your risk of encountering extreme fire behavior. When this occurs it is essential that firefighters understand the fire behavior, their own reactions to stress, and have well practiced (to automaticity) responses to increase the chance of survival.

Training for Survival

What exactly are firefighter survival skills? Firefighters may encounter a number of life threatening problems while operating in the hazardous environment of as structure fire. Threats include breathing apparatus emergencies (e.g., malfunctions, running out of air), becoming disoriented, and being trapped by collapse or rapid fire progress.

A quick survey of survival skills training programs from around the United States shows a fair degree of consistency in curriculum content:

• Emergency Communications Procedures (Mayday, Radio Emergency Distress Button)
• Personal Alert Safety System (PASS) Activation
• Reorientation, Searching for an Exit & Following a Hoseline to Safety
• Air Conservation Techniques
• Assuming a Horizontal Position to Enhance Thermal Protection and Audibility of the PASS
• Escape to a Place of Refuge
• Use of Visual and Audible Signals (Flashlight, Tapping with a Tool)
• Reduced Profile Maneuvers to Escape Through Small Openings
• Emergency Window Egress (Ladder Bail, Rope Systems)

These techniques may provide useful in dealing with a number of the threats that may be encountered in a structure fire. Taking refuge in an uninvolved compartment (with the door closed) may buy time for firefighters to escape through a window. However, the other elements will have little impact on increasing survival potential when encountering extreme fire behavior phenomena.

What is the missing element in the typical survival skills curriculum? In some cases, firefighters are taught breathing techniques to control their respiratory rate and conserve air, but little emphasis is provided on the psychological and physiological effects of the stress encountered in life threatening situations. This is critical to survival regardless of the nature of the threat. When faced with extreme fire behavior, particularly wind driven flames, flashover, and flash fire, appropriate nozzle technique and immediate tactical withdrawal to a safer area is absolutely critical. However, most survival skills curriculums do not address these critical skills.

When was the last time you practiced withdrawing a hoseline while operating the nozzle in the context of offensive, interior firefighting operations?

Performance Under Stress

There has been little if any research has been done to identify factors influencing firefighters� performance under the extreme stress of a life threatening situation. However, there has been considerable investigation in other domains, particularly in the military and law enforcement

Increased psychological and physiological arousal prepare the human body for action. As this occurs, the sympathetic nervous system increases heart rate and blood pressure to maximize the body�s physical capacity. However, extreme levels of stress can result in significant deterioration in performance.

In On-Combat: The Psychology and Physiology of Deadly Conflict in War and Peace, LT COL Dave Grossman (2008) identifies five levels of arousal designated Conditions White, Yellow, Red, Grey, and Black. While cautioning against fixing specific heart rate numbers (or other precise physiological measures) to these levels of arousal, heart rate can be used as an indicator (see Figure 2).

Figure 2. Effects of Hormonal or Fear Induced Increases in Heart Rate

Note. Adapted from On-Combat: The Psychology and Physiology of Deadly Conflict in War and Peace (p. 31), by Dave Grossman, 2008, Millstadt, IL: Warrior Science Publications Copyright 2008 by David A. Grossman.

When face with an immediately life threatening situation, the resulting stress can significantly impact an individual�s ability to respond appropriately. In addition to the physiological responses (e.g. increased heart rate, visual and auditory distortion) decreased cognitive processing may delay appropriate response or result in freezing, with the inability to act (Wallenius, Johansson, & Larsson, 2002).

Recently a colleague related the experience of a firefighter who had been trapped by a wind driven fire. The firefighter dropped to the floor, went into the fetal position, said goodby to his wife and children and thought he was dead. Fortunately, the firefighter was rescued, but this illustrates the potentially incapacitating effects of stress in life threatening situations.

What is the answer? Military research points to the need for a highly trained (to automaticity) response. Battle drills integrate these immediate individual actions in the context of small unit operations.

Battle Drill

In a military context, battle drills are an immediate response to enemy contact that requires fire and maneuver in order to succeed. Battle drills are initiated with minimal commands from the unit leader. Soldiers or marines execute preplanned, sequential actions in response to enemy contact.

The battle drill concept has direct applicability to training firefighters to react appropriately on contact with our enemy (the fire) which requires fire (application of water) and maneuver (movement to a safer location) in order to succeed.

Unless a barrier (such as a door) is available to block the flow of flames and hot gases towards the firefighters position, attempts to escape without protection from a hoseline are likely to fail as fire can spread far more quickly than you can move.

Remember: The key elements of a battle drill are fire and maneuver! This requires the ability to operate and maintain control of the hoseline while moving backward.

The next post in this series will return to hose and nozzle drills with development of a battle drill for response to rapid fire progression.

Ed Hartin, MS, EFO, MIFireE, CFO.

References

Grossman, D. (2008). On-combat: The psychology and physiology of deadly conflict in war and peace. Millstadt, IL: Warrior Science Publications.

Wallenius, C. Johansson, C. & Larsson, G. (2002). Reactions and performance of Swedish peacekeepers in life-threatening situations. International Peacekeeping, 9(1), 133-152.

This post continues study of an incident in a townhouse style apartment building in Washington, DC with examination of the extreme fire behavior that took the lives of Firefighters Anthony Phillips and Louis Mathews. As discussed in Townhouse Fire: Washington, DC-Computer Modeling Part I, this was one of the first cases where the NIST Fire Dynamics Simulator (FDS) software was used in forensic fire scene reconstruction (Madrzykowski and Vettori, 2000).

Quick Review

As discussed in prior posts, crews working on Floor 1 to locate the fire and secure the door to the stairwell were trapped and burned as a result of rapid progression of a fire in the basement up the open interior stairway after an exterior sliding glass door was opened to provide access to the basement. For detailed examination of incident operations and fire behavior, see:

• Fire Behavior Case Study Townhouse Fire: Washington, DC
• Townhouse Fire: Washington DC-What Happened
• Townhouse Fire: Washington DC-Extreme Fire Behavior
• Townhouse Fire: Washington DC-Computer Modeling

Figure 1. Conditions at Approximately 00:28

Note: From Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 29 & 32. District of Columbia Fire & EMS, 2000.

Smokeview

Smokeview is a visualization program used to provide a graphical display of a FDS model simulation in the form of an animation or snapshot. Snapshots illustrate conditions in a specific plane or slice within the building. Three vertical slices are important to understanding the fire dynamics involved in the Cherry Road incident: 1) midline of the door on Floor 1, Side A, 2) midline of the Basement Door, Side C, and midline of the Basement Stairwell (see Figure 2). Imagine that the building is cut open along the slice and that you can observe the temperature, oxygen concentration, or velocity of gas movement within that plane.

Figure 2. Perspective View of 3146 Cherry Road and Location of Slices

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 15) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

In addition to having an influence on heat release rate, the location and configuration of exhaust and inlet openings determines air track (movement of smoke and air) and the path of fire spread. In this incident, the patio door providing access to the basement at the rear acted as an inlet, providing additional air to the fire. The front door and windows on the first floor opened for ventilation served as exhaust openings and provided a path for fire travel when the conditions in the basement rapidly transitioned to a fully developed fire.

Figures 3-10 illustrate conditions at 200 seconds into the simulation, which relates to approximately 00:27 during the incident, the time at which the fire in the basement transitioned to a fully developed stage and rapidly extended up the basement stairway to Floor 1. Data is presented as a snapshot within a specific slice. Temperature and velocity data are provide for each slice (S1, S2, & S3 as illustrated in Figure 2).

Figure 3. Temperature Along Centerline of Basement Door Side C (S1) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 17) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 4. Vector Representation of Velocity Along Centerline of Basement Door Side C (S1) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 18) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 5. Oxygen Concentration Along Centerline of Basement Door Side C (S1) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 23) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 6. Temperature Slice Along Centerline of Basement Stairwell (S2) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 21) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 7. Vector Representation of Velocity Along Centerline of Basement Stairwell (S2) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 22) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 8. Oxygen Concentration Along Centerline of Basement Stairwell (S2) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 24) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 9. Temperature Slice Along Centerline of Floor 1 Door Side A (S3) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 19) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 10. Vector Representation of Velocity Along Centerline of Floor 1 Door Side A (S3) at 200 s

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 20) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 11. Perspective Cutaway, Flow/Temperature, Velocity, and O₂ Concentration

Figure 12. Thermal Exposure Limits in the Firefighting Environment

Note: Adapted from Measurements of the firefighting environment. Central Fire Brigades Advisory Council Research Report 61/1994 by J.A. Foster & G.V. Roberts, 1995. London: Department for Communities and Local Government and Thermal Environment for Electronic Equipment Used by First Responders by M.K. Donnelly, W.D. Davis, J.R. Lawson, & M.J. Selepak, 2006, Gaithersburg, MD: National Institute of Standards and Technology.

Compartment Fire Thermal Hazards

The temperature of the atmosphere (i.e., smoke and air) is a significant concern in the fire environment, and firefighters often wonder or speculate about how hot it was in a particular fire situation. However, gas temperature in the fire environment is a bit more complex than it might appear on the surface and is only part of the thermal hazard presented by compartment fire.

Tissue temperature and depth of penetration determine the severity of a thermal burn. Temperature and penetration are dependent on the amount of energy absorbed and the duration of the thermal insult as well as the properties of human tissue. In a compartment fire, firefighters absorb energy from any substance that has a temperature above 37^o C (98.6^o F), including hot compartment linings, contents, the hot gas layer, and flames. The dominant mechanisms of heat transfer involved in this process are convection and radiation (although conduction through personal protective equipment is also a factor to be considered).

The total thermal energy received is described in joules per unit area. However, the speed or rate of energy is transferred may be more important when assessing thermal hazard. Heat (thermal) flux is used to define the rate of heat transfer and is expressed in kW/m² (Btu/hr/ft²).

One way to understand the interrelated influence of radiant and convective heat transfer is to consider the following scenario. Imagine that you are standing outside in the shade on a hot, sunny day when the temperature is 38^o C (100^o F). As the ambient temperature is higher than that of your body, energy will be transferred to you from the air. If you move out of the shade, your body will receive additional energy as a result of radiant heat transfer from the sun.

Convective heat transfer is influenced by gas temperature and velocity. When hot gases are not moving or the flow of gases across a surface (such as your body or personal protective equipment) is slow, energy is transferred from the gases to the surface (lowering the temperature of the gases, while raising surface temperature). These lower temperature gases act as an insulating layer, slowing heat transfer from higher temperature gases further away from the surface. When velocity increases, cooler gases (which have already transferred energy to the surface) move away and are replaced by higher temperature gases. When velocity increases sufficiently to result in turbulent flow, hot gases remain in contact with the surface on a relatively constant basis, increasing convective heat flux.

Radiant heat transfer is influenced by proximity and temperature of the radiating body. Radiation increases by a factor of four when distance to the hot material is reduced by half. In addition, radiation increases exponentially (as a function of the fourth power) as absolute temperature increases.

Thermal hazard may be classified based on hot gas temperature and radiant heat flux (Foster & Roberts, 1995; Donnelly, Davis, Lawson, & Selpak, 2006) with temperatures above 260^o C (500^o F) and/or radiant heat flux of 10 kW/m² (3172 Btu/hr/ft²) being immediately life threatening to a firefighter wearing a structural firefighting ensemble (including breathing apparatus). National Institute of Standards and Technology (NIST) experiments in a single compartment show post flashover gas temperatures in excess of 1000^o C (1832^o F) and heat flux at the floor may exceed 170 kW/m² (Donnelly, Davis, Lawson, & Selpak, 2006). Post flashover conditions in larger buildings with more substantial fuel load may be more severe!

Figure 11 integrates temperature, velocity, and oxygen concentration data from the simulation (Figures 3-10). Detail and accuracy is sacrificed to some extent in order to provide a (somewhat) simpler view of conditions at 200 seconds into the simulation (approximately 00:27 incident time). Note that as in individual slices, data is presented as a range due to uncertainty in the computer model.

Alternative Model

In addition to modeling fire dynamics based on incident conditions and tactical operations as they occurred, NIST also modeled the incident with a slightly different ventilation profile.

The basic input for the alternate simulation was the same as the simulation of actual incident conditions. Ventilation openings and timing was the same, with one exception; the sliding glass door on Floor 1, Side C was opened at 120 s into the simulation. Conditions in the basement during the alternative simulation were similar to the first. However, on Floor 1, the increase in ventilation provided by the sliding glass door on Side C resulted in a shallower hot gas layer and cooler conditions at floor level. A side-by-side comparison of the temperature gradients in these two simulations is provided in Figure 13.

Figure 13. Comparison of Temperature Gradients Along Centerline of Basement Stairwell (S2) at 200 s

Note: Adapted from Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 21 & 27) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

The NIST Report (Madrzykowski & Vettori, 2000) identified that the significant difference between these two simulations is in the region close to the floor. In the alternative simulation (Floor 1, Side C Sliding Glass Door Open) between the doorway to the basement and the sofa, the temperatures from approximately 0.6 m (2 ft) above the floor, to floor level are in the range of 20 �C to 100 �C (68�F to 212 �F), providing at least an 80 �C (176 �F) temperature reduction.

While this is a considerable reduction in gas temperature, it is essential to also consider radiant heat flux from the hot gas layer. Given the temperature of the hot gases from the ceiling level to a depth of approximately 3′ (0.9 m), the heat flux at the floor would likely have been in the range of 15-20 kW/m² (or greater).

Questions

1. Temperatures vary widely at a given elevation above the floor. Consider the slices illustrated in Figures 3, 6, and 9, and identify factors that may have influenced these major differences in temperature.
2. How might the variations in temperature illustrated in Figures 3, 6, and9 and location of Firefighters Phillips (basement doorway), Mathews (living room, C/D corner), and Morgan (between Phillips & Mathews) have influenced their injuries?
3. Examine the velocity of gas movement illustrated in Figures 4, 7, and 10 and integrated illustration conditions in Figure 11. How does this correlate to the photos in Figure 1 illustrating incident conditions at approximately 00:28?
4. Explain how the size and configuration of ventilation openings resulted in a bi-directional air track at the basement door on Side C.
5. How did the velocity of hot gases in the stairwell and living room influence the thermal insult to Firefighters Phillips, Mathews, and Morgan? What factors caused the high velocity flow of gases from the basement stairwell doorway into the living room?
6. Rescue 1B noted that the floor in the living room was soft while conducting primary search at approximately 00:30. Why didn’t the parallel chord trusses in the basement fail sooner? Is there a potential relationship between fire behavior and performance of the engineered floor support system in this incident?
7. How might stability of the engineered floor support system have differed if the sliding glass door in the basement had failed prior to the fire departments arrival? Why?
8. How might the double pane glazing on the windows and sliding glass doors have influenced fire development in the basement? How might fire development differed if these building openings had been fitted with single pane glazing?
9. What was the likely influence of turbulence in the flow of hot gases and cooler air on combustion in the basement? What factors influenced this turbulence (examine Figures 4, 7, and 10) illustrating velocity of flow and floor plan illustrated in conjunction with the second question)?
10. How did conditions in the area in which Firefighters Phillips, Mathews, and Morgan were located correlate to the thermal exposure limits defined in Figure 12? How did this change in the alternate scenario? Remember to consider both temperature and heat flux.

Extended Learning Activity

The Cherry Road case study provides an excellent opportunity to develop an understanding of the influence of building factors, burning regime, ventilation, and tactical operations on fire behavior. These lessons can be extended by comparing and contrasting this case with other cases such as the 1999 residential fire in Keokuk, Iowa that took the lives Assistant Chief Dave McNally, Firefighter Jason Bitting, and Firefighter Nathan Tuck along with three young children. For information on this incident see NIOSH Death in the Line of Duty Report F2000-4, NIST report Simulation of the Dynamics of a Fire in a Two Story Duplex, NIST IR 6923.and video animation of Smokeview output from modeling of this incident

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

This post continues study of an incident in a townhouse style apartment building in Washington, DC with examination of the extreme fire behavior that took the lives of Firefighters Anthony Phillips and Louis Mathews.

A Quick Review

Prior posts in this series, Fire Behavior Case Study of a Townhouse Fire: Washington, DC, Townhouse Fire: Washington, DC-What Happened,and Townhouse Fire: Washington, DC-Extreme Fire Behavior examined the building and initial tactical operations at this incident. The fire occurred in the basement of a two-story, middle of building, townhouse apartment with a daylight basement. This configuration provided at grade entrances to Floor 1 on Side A and the Basement on Side C.

Engine 26, the first arriving unit reported heavy smoke showing from Side A and observed a bi-directional air track at the open front door. Engines 26 and 10 operating from Side A deployed hoselines into the first floor to locate the fire. Engine 17, the second due engine, was stretching a hoseline to Side C, but had insufficient hose and needed to extend their line. Truck 4, the second due truck, operating from Side C opened a sliding glass door to the basement to conduct search and access the upper floors (prior to Engine 17′s line being in position). When the door on Side C was opened, Truck 4 observed a strong inward air track. As Engine 17 reached Side C (shortly after Rescue 1 and a member of Truck 4 entered the basement) and asked for their line to be charged. Engine 17 advised Command that the fire was small.

Conditions changed quickly after the door on Side C was opened, as conditions in the basement rapidly transitioned to a fully developed fire with hot gases and flames extending up the interior stairway trapping Firefighters Phillips, Mathews, and Morgan. Confusion about building configuration (particularly the number of floors and location of entry points on Side A and C) delayed fire attack due to concern for opposing hoselines.

Modeling of the Cherry Road Incident

National Institute for Standards and Technology (NIST) performed a computer model of fire dynamics in the fire at 3146 Cherry Road (Madrzykowski and Vettori, 2000) using the NIST Fire Dynamics Simulator (FDS) software. This is one of the first cases where FDS was used in forensic fire scene reconstruction.

Fire Modeling

Fire modeling is a useful tool in research, engineering, fire investigation, and learning about fire dynamics. However, effective use of this tool and the information it provides requires understanding of its capabilities and limitations.

Models, such as the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) relay on computational fluid dynamics (CFD). CFD models define the fire environment by dividing it into small, rectangular cells. The model simultaneously solves mathematical equations for combustion, heat transfer, and mass transport within and between cells. When used with a graphical interface such as NIST Smokeview, output can be displayed in a three-dimensional (3D) visual format.

Models must be validated to determine how closely they match reality. In large part this requires comparison of model output to full scale fire tests under controlled conditions. When used for forensic fire scene reconstruction, it may not be feasible to recreate the fire to test the model. In these situations, model output is compared to physical evidence and interview data to determine how closely key aspects of model output matched events as they occurred. If model output reasonably matches events as they occurred, it is likely to be useful in understanding the fire dynamics involved in the incident.

It is crucial to bear in mind that fire models do not provide a reconstruction of the reality of an event. They are simplified representation of reality that will always suffer from a certain lack of accuracy and precision. Under the condition that the user is fully aware of this status and has an extensive knowledge of the principles of the models, their functioning, their limitations and the significance attributed to their results, fire modeling becomes a very powerful tool (Dele�mont & Martin, J., 2007, p. 134).

FDS output included data on heat release rate, temperature, oxygen concentration, and velocity of gas (smoke and air) movement within the townhouse. As indicated above, model output is an approximation of actual incident conditions.

In large scale fire tests (McGrattan, Hamins, & Stroup, 1998, as cited in Madrzykowski and Vettori, 2000), FDS temperature predictions were found to be within 15% of the measured temperatures and FDS heat release rates were predicted to within 20% of the measured values. For relatively simple fire driven flows such as buoyant plumes and flows through doorways, FDS predictions are within experimental uncertancies (McGrattan, Baum, & Rehm, 1998, as cited in Madrzykowski and Vettori, 2000).

Results presented in the NIST report on the fire at 3146 Cherry Road were presented as ranges to account for potential variation between model output and actual incident conditions.

Heat release rate is dependent on the characteristics and configuration of the fuel packages involved and available oxygen. In a compartment fire, available oxygen is dependent on the ventilation profile (i.e., size and location of compartment openings). The ventilation profile can change over time due to the effects of the fire (e.g., failure of window glazing) as well as human action (i.e., doors left open by exiting occupants, tactical ventilation, and tactical anti-ventilation)

In this incident there were a number of changes to the ventilation profile. Most significant of which were, 1) the occupant opened the second floor windows on Side C (see Figure 3), 2) the occupant left the front door open as they exited (see Figures 1 &2 ), 3) tactical ventilation of the first floor window on Side A, and opening of the sliding glass door in the basement on Side C (see Figures 1-3). In addition, the open door in the basement stairwell and open stairwell between the Floors 1 and 2 also influenced the ventilation profile (see Figure 1).

Figure 1. Cross Section of 3146 Cherry Road NE

Figure 2. Side A 3146 Cherry Road NE

Figure 3. Side C 3146 Cherry Road NE

Figure 4 illustrates the timing of changes to the ventilation profile and resulting influence on heat release rate in modeling this incident. A small fire with a specific heat release rate (HRR) was used to start fire growth in the FDS simulation. In the actual incident it may have taken hours for the fire to develop flaming combustion and progression into the growth stage. Direct comparison between the simulation and incident conditions began at 100 seconds into the simulation which corresponds to approximately 00:25 during the incident.

Figure 4. FDS Heat Release Rate Curve

Note: Adapted from Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 14) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Questions

The following questions are based on heat release rate data from the FDS model presented in Figure 4.

1. What was the relationship between changes in ventilation profile and heat release rate?
2. What would explain the rapid increase in heat release rate after the right side of the basement sliding glass door is opened?
3. Why might the heat release rate have dropped slightly prior to opening of the left side of the basement sliding glass door?
4. Why did the heat release rate again increase rapidly to in excess of 10 MW after the left side of the basement sliding glass door was opened?
5. How does data from the FDS model correlate to the narrative description of events presented in prior posts about this incident (Fire Behavior Case Study of a Townhouse Fire: Washington, DC, Townhouse Fire: Washington, DC-What Happened,and Townhouse Fire: Washington, DC-Extreme Fire Behavior)?

More to Follow

In addition to heat release rate data the computer modeling of this incident provided data on temperature, oxygen concentration, and gas velocity. Visual presentation of this data provides a more detailed look at potential conditions inside the townhouse during the fire. The next post in this series will present and examine graphic output from Smokeview to aid in understanding the fire dynamics and thermal environment encountered during this incident.

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

This post continues study of an incident in a townhouse style apartment building in Washington, DC with examination of the extreme fire behavior that took the lives of Firefighters Anthony Phillips and Louis Mathews.

A Quick Review

Prior posts in this series, Fire Behavior Case Study of a Townhouse Fire: Washington, DC and Townhouse Fire: Washington, DC-What Happened examined the building and initial tactical operations at this incident. The fire occurred in the basement of a two-story, middle of building, townhouse style apartment with a daylight basement. This configuration provided an at grade entrance to the Floor 1 on Side A and at grade entrance to the Basement on Side C.

Engine 26, the first arriving unit reported heavy smoke showing from Side A and observed a bi-directional air track at the open front door. First alarm companies operating on Side A deployed hoselines into the first floor to locate the fire. Engine 17, the second due engine, was stretching a hoseline to Side C, but had insufficient hose and needed to extend their line. Truck 4, the second due truck, operating from Side C opened a sliding glass door to the basement to conduct search and access the upper floors (prior to Engine 17′s line being in position). When the door on Side C was opened, Truck 4 observed a strong inward air track. As Engine 17 reached Side C (shortly after Rescue 1 and a member of Truck 4 entered the basement) and asked for their line to be charged, and Engine 17 advised Command that the fire was small.

Extreme Fire Behavior

Proceeding from their entry point on Side C towards the stairway to Floor 1 on Side A, Rescue 1B and the firefighter from Truck 4 observed fire burning in the middle of the basement room. Nearing the stairs, temperature increased significantly and they observed fire gases in the upper layer igniting. Rescue 1B and the firefighter from Truck 4 escaped through the basement doorway on Side C as the basement rapidly transitioned to a fully developed fire.

Figure 1. Timeline Leading Up to the Extreme Fire Behavior Event

The timeline illustrated in Figure 1 is abbreviated and focuses on a limited number of factors. A detailed timeline, inclusive of tactical operations, fire behavior indicators, and fire behavior is provided in a subsequent section of the case.

After Engine 17′s line was charged, the Engine 17 officer asked Command for permission to initiate fire attack from Side C. Command denied this request due to lack of contact with Engines 26 and 10 and concern regarding opposing hoselines. Due to their path of travel around Side B of the building, Engine 17 had not had a clear view of Side A and thought that they were at a doorway leading to Floor 1 (rather than the Basement). At this point, neither the companies on Side C nor Command recognized that the building had three levels on Side C and two levels on Side A.

At this point crews from Engine 26 and 10 are operating on Floor 1 and conditions begin to deteriorate. Firefighter Morgan (Engine 26) observed flames at the basement door in the living room (see Figure 8 which illustrates fire conditions in the basement as seen from Side C). Firefighter Phillips (Engine 10) knocked down visible flames at the doorway, but conditions continued to deteriorate. Temperature increased rapidly while visibility dropped to zero.

As conditions deteriorated, Engine 26′s officer feels his face burning and quickly exits (without notifying his crew). In his rapid exit through the hallway on Floor 1, he knocked the officer from Engine 10 over. Confused about what was happening Engine 10′s officer exited the building as well (also without notifying his crew). Engine 26′s officer reports to Command that Firefighter Mathews was missing, but did not report that Firefighter Morgan was also missing. Appearing dazed, Engine 10′s officer did not report that Firefighter Phillips was missing.

Figure 2. Conditions on Side C at Aproximately 00:28

Note: From Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 32. District of Columbia Fire & EMS, 2000.

Figure 3. Conditions on Side A at Aproximately 00:28

Note: From Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 29. District of Columbia Fire & EMS, 2000.

Firefighter Rescue Operations

After the exit of the officers from Engine 26 and Engine 10, the three firefighters (Mathews, Phillips, and Morgan) remained on Floor 1. However, neither Command (Battalion 1) nor a majority of the other personnel operating at the incident recognized that the firefighters from Engines 26 and 10 had been trapped by the rapid extension of fire from the Basement to Floor 1 (see Figure 4).

While at their apparatus getting a ladder to access the roof from Side B, Truck 4B observed the rapid fire development in the basement and pulled a 350′ 1-1/2″ (107 m 38 mm) line from Engine 12 to Side C, backing up Engine 17.

Figure 4. Location of Firefighters on Floor 1

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 18 & 20. District of Columbia Fire & EMS, 2000 and Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 12-13, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology.

Engine 17 again contacted Command (Battalion 1) and requested permission to initiate an exterior attack from Side C. However, the officer of Engine 17 mistakenly advised Command that there was no basement entrance and that his crew was in position to attack the fire on Floor 1. Unable to contact Engines 10 and 26, Command denied this request due to concern for opposing hoselines. With conditions worsening, Command (Battalion 1) requested a Task Force Alarm at 00:29, adding another two engine companies, truck company, and battalion chief to the incident.

Firefighter Phillips (E-10) attempted to retreat from his untenable position at the open basement door. He was only able to travel a short distance before he collapsed. Firefighter Morgan (E-26) heard a loud scream to his left and then a thud as if someone had fallen to the floor (possibly Firefighter Mathews (E-26)). Firefighter Morgan found the attack line and opened the nozzle on a straight stream, penciling the ceiling twice before following the hoseline out of the building (to Side A). Firefighter Morgan exited the building at approximately 00:30.

Rescue 1B entered the structure on Floor 1, Side A to perform a primary search. They crawled down the hallway on Floor 1 towards Side C until they reached the living room and attempted to close the open basement door but were unable to do so. Rescue 1 B did not see or hear Firefighters Mathews (E-26) and Phillips (E-10) while working on Floor 1. Rescue 1B noted that the floor in the living room was spongy. The Rescue 1 Officer ordered his B Team to exit, but instead they returned to the front door and then attempted to search Floor 2, but were unable to because of extremely high temperature.

Unaware that Firefighter Phillips (E-10) was missing, Command tasked Engine 10� and Rescue 1A, with conducting a search for Firefighter Mathews (E-26). The Engine 10 officer entered Floor 1 to conduct the search (alone) while instructing another of his firefighters to remain at the door. Rescue 1A followed Engine 26′s 1-1/2″ (38 mm) hoseline to Floor 1 Slide C. Rescue 1B relocated to Side B to search the basement for the missing firefighter.

The Engine 26 Officer again advised Command (Battalion 1) that Firefighter Mathews was missing. Engine 17 made a final request to attack the fire from Side C. Given that a firefighter was missing and believing that the fire had extended to Floor 1, Command instructed Engine 17 to attack the fire with a straight stream (to avoid pushing the fire onto crews working on Floor 1). At approximately 00:33, Battalion 2 reported (from Side C) that the fire was darkening down. Engine 14 arrived and staged on Bladensburg Road.

Command ordered a second alarm assignment at 00:34 hours. At 00:36, Command ordered Battalion 2 (on Side C) to have Engine 17 and Truck 4 search for Firefighter Mathews in the Basement. Engine 10′s officer heard a shrill sound from a personal alert safety system (PASS) and quickly located Firefighter Phillips (E-10). Firefighter Phillips was unconscious, lying on the floor (see Figure 4) with his facepiece and hood removed. Unable to remove Firefighter Phillips by himself, the officer from Engine 10 unsuccessfully attempted to contact Command (Battalion 1) and then returned to Side A to request assistance.

Command received a priority traffic message at 00:37, possibly attempting to report the location of a missing firefighter. However, the message was unreadable.

The Hazmat Unit and Engine 6 arrived and staged on Bladensburg Road and a short time later were tasked by Command to assist with rescue of the downed firefighter on Floor 1. Firefighter Phillips (E-10) was removed from the building by the Engine 10 officer, Rescue 1A, Engine 6, and the Hazardous Materials Unit at 00:45. After Firefighter Phillips was removed to Side A, Command discovered that Firefighter Mathews (E-26) was still missing and ordered the incident safety officer to conduct an accountability check. Safety attempted to conduct a personnel accountability report (PAR) by radio, but none of the companies acknowledged his transmission.

The Deputy Chief of the Firefighting Division arrived at 00:43 and assumed Command, establishing a fixed command post at the Engine 26 apparatus. Battalion 4 arrived a short time later and was assigned to assist with rescue operations along with Engines 4 and 14.

Firefighter Mathews was located simultaneously by several firefighters. He was unconscious leaning over a couch on Side C of the living room (see Figure 4). Firefighter Mathews breathing apparatus was operational, but he had not activated his (non-integrated) personal alert safety system (PASS). Firefighter Mathews was removed from the building by Engine 4, Engine 14, and Hazardous Materials Unit at 00:49.

Command (Deputy Chief) ordered Battalions 2 and 4 to conduct a face-to-face personnel accountability report on Sides A and C at 00:53.

Questions

1. Based on the information provided in the case to this point, answer the following questions:
2. National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty Reports examining incidents involving extreme fire behavior often recommend close coordination of fire attack and ventilation.
3. Did the fire behavior in this incident match the prediction you made after reading the previous post (Towhouse Fire: Washington DC-What Happened)?
4. What type of extreme fire behavior occurred? Justify your answer?
5. What event or action initiated the extreme fire behavior? Why do you believe that this is the case?
6. How did building design and construction impact on fire behavior and tactical operations during this incident?
7. How might a building pre-plan and/or 360^o reconnaissance have impacted the outcome of this incident? Note that 360^o reconnaissance does not necessarily mean one individual walking completely around the building, but requires communication and knowledge of conditions on all sides of the structure (e.g., two stories on Side A and three stories on Side C).
8. How might the outcome of this incident have changed if Engine 17 had been in position and attacked the fire in the basement prior to Engines 26 and 10 committing to Floor 1?
9. What strategies and tactics might have been used to mitigate the risk of extreme fire behavior during this incident?

More to Follow

This incident was one of the first instances where the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) was used in forensic fire scene reconstruction (Madrzykowski & Vettori, 2000). Modeling of the fire behavior in this incident helps illustrate what was likely to have happened in this incident. The next post in this series will examine and expand on the information provided by modeling of this incident.

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

This post continues study of an incident that resulted in two line-of-duty deaths as a result of extreme fire behavior in a townhouse style apartment building in Washington, DC.

A Quick Review

The previous post in this series, Fire Behavior Case Study of a Townhouse Fire: Washington, DC examined building construction and configuration that had a significant impact on the outcome of this incident. The fire occurred in the basement of a two-story, middle of building, townhouse style apartment with a daylight basement. This configuration provided an at grade entrance to the Floor 1 on Side A and an at grade entrance to the Basement on Side C.

The fire originated in an electrical junction box attached to a fluorescent light fixture in the basement ceiling (see Figures 1 and 2). The occupants of the unit were awakened by a smoke detector. The female occupant noticed smoke coming from the floor vents on Floor 2. She proceeded downstairs and opened the front door and then proceeded down the first floor hallway towards Side C, but encountered thick smoke and high temperature. The female and male occupants exited the structure, leaving the front door open, and made contact with the occupant of an adjacent unit who notified the DC Fire & EMS Department at 0017 hours.

Dispatch Information

At 00:17, DC Fire & EMS Communications Division dispatched a first alarm assignment consisting of Engines 26, 17, 10, 12, Trucks 15, 4, Rescue Squad 1, and Battalion 1 to 3150 Cherry Road NE. At 0019 Communications received a second call, reporting a fire in the basement of 3146 Cherry Road NE. Communications transmitted the update with the change of address and report of smoke coming from the basement. However, only one of the responding companies (Engine 26) acknowledged the updated information.

Weather Conditions

Temperature was approximately 66^o F (19^o C) with south to southwest winds at 5-10 mi/hr (8-16 km/h), mostly clear with no precipitation.

Conditions on Arrival

Approaching the incident, Engine 26 observed smoke blowing across Bladensburg Road. Engine 26 arrived at a hydrant at the corner of Banneker Drive and Cherry Road at 00:22 hours and reported smoke showing. A short time later, Engine 26 provided an updated size-up with heavy smoke showing from Side A of a two story row house. Based on this report, Battalion 1 ordered a working fire dispatch and a special call for the Hazmat Unit at 00:23. This added Engine 14, Battalion 2, Medic 17 and EMS Supervisor, Air Unit, Duty Safety Officer, and Hazmat Unit.

Firefighting Operations

DC Fire and EMS Department standard operating procedures (SOP) specify apparatus placement and company assignments based on dispatch (anticipated arrival) order. Note that dispatch order (i.e., first due, second due) may de different than order of arrival if companies are delayed by traffic or are out of quarters.

Standard Operating Procedures

Operations from Side A

The first due engine lays a supply line to Side A, and in the case of basement fires, the first line is positioned to protect companies performing primary search on upper floors by placing a line to cover the interior stairway to the basement. The first due engine is backed up by the third due engine. The apparatus operator of the third due engine takes over the hydrant and pumps supply line(s) laid by the first due engine, while the crew advances a backup line to support protection of interior exposures and fire attack from Side A.

The first due truck takes a position on Side A and is responsible for utility control and placement of ladders for access, egress, and rescue on Side A. If not needed for rescue, the aerial is raised to the roof to provide access for ventilation.

The rescue squad positions on Side A (unless otherwise ordered by Command) and is assigned to primary search using two teams of two. One team searches the fire floor, the other searches above the fire floor. The apparatus operator assists by performing forcible entry, exterior ventilation, monitoring search progress, and providing emergency medical care as necessary.

Operations from Side C

The second due engine lays a supply line to the rear of the building (Side C), and in the case of basement fires, is assigned to fire attack if exterior access to the basement is available and if it is determined that the first and third due engines are in a tenable position on Floor 1. The second due engine is responsible for checking conditions in the basement, control of utilities (on Side C), and notifying Command of conditions on Side C. Command must verify that the first and third due engines can maintain tenable positions before directing the second due engine to attack basement fires from the exterior access on Side C.

The second due truck takes a position on Side C and is responsible for placement of ladders for access, egress, and rescue on Side C. The aerial is raised to the roof to provide secondary access for ventilation (unless other tasks take priority).

Command and Control

The battalion chief positions to have an unobstructed view of the incident (if possible) and uses his vehicle as the command post. On greater alarms, the command post is moved to the field command unit.

Notes: This summary of DC Fire & EMS standard operating procedures for structure fires is based on information provided in the reconstruction report and reflects procedures in place at the time of the incident. DC Fire & EMS did not use alpha designations for the sides of a building at the time of this incident. However, this approach is used here (and throughout the case) to provide consistency in terminology.

First due, Engine 26 laid a 3″ (76 mm) supply line from a hydrant at the intersection of Banneker Drive and Cherry Road NE, positioned in the parking lot on Side A, and advanced a 200′ 1-1/2″ ( 61 m 38 mm) pre-connected hoseline to the first floor doorway of the fire unit on Side A (see Figures 1 and 2). A bi-directional air track was evident at the door on Floor 1, Side A , with thick (optically dense) black smoke from the upper area of the open doorway. Engine 26′s entry was delayed due to a breathing apparatus facepiece malfunction. The crew of Engine 26 (Firefighters Mathews and Morgan and the Engine 26 Officer) made at approximately 00:24.

Figure 1. Plot and Floor Plan-3146 Cherry Road NE

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 18 & 20. District of Columbia Fire & EMS, 2000; Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 12-13, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology, and NIOSH Death in the Line of Duty Report 99 F-21, 1999, p. 19.

Engine 10, the third due engine arrived shortly after Engine 26, took the hydrant at the intersection of Banneker Drive and Cherry Road, NE, and pumped Engine 26′s supply line. After Engine 10 arrived at the hydrant, the firefighter from Engine 26 who had remained at the hydrant proceeded to the fire unit and rejoined his crew. Engine 10, advanced a 400′ 1-1/2″ (122 m 38 mm) line from their own apparatus as a backup line. Firefighter Phillips and the Engine 10 officer entered through the door on Floor 1, Side A (see Figure 2) while the other member of their crew remained at the door to assist in advancing the line.

Truck 15, the first due truck arrived at 00:23 and positioned on Side A in the parking lot behind Engine 26. The crew of Truck 15 began laddering Floor 2, Side A, and removed kitchen window on Floor 1, Side A (see Figure 2). Due to security bars on the window, one member of Truck 15 entered the building and removed glass from the window from the interior. After establishing horizontal ventilation, Truck 15 accessed the roof via a portable ladder and began vertical ventilation operations.

Engine 17, the second due engine, arrived at 00:24, laid a 3″ (76 mm) supply line from the intersection of Banneker Drive and Cherry Road NE, to a position on Cherry Road NE just past the parking lot, and in accordance with department procedure, stretched a 350′ 1-1/2″ (107 m 38 mm) line to Side C (see Figure 2).

Approaching Cherry Road from Banneker Drive, Battalion 1 observed a small amount of fire showing in the basement and assigned Truck 4 to Side C. Battalion 1 parked on Cherry Road at the entrance to the parking lot, but was unable to see the building, and proceeded to Side A and assumed a mobile command position.

Second due, Truck 4 proceeded to Side C and observed what appeared to be a number of small fires in the basement at floor level (this was actually flaming pieces of ceiling tile which had dropped to the floor). The officer of Truck 4 did not provide a size-up report to Command regarding conditions on Side C. Truck 4, removed the security bars from the basement sliding glass door using a gasoline powered rotary saw and sledgehammer. After clearing the security grate Truck 4, broke the right side of the sliding glass door to ventilate and access the basement (at approximately 00:27) and then removed the left side of the sliding glass door. The basement door on Side C was opened prior to Engine 17 getting a hoseline in place and charged. After opening the sliding glass door in the basement, Truck 4 attempted to ventilate windows on Floor 2 Side C using the tip of a ladder. They did not hear the glass break and believing that they had been unsuccessful; they left the ladder in place at one of the second floor windows and continued with other tasks.

Figure 2. Location of First Alarm Companies and Hoselines

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 27. District of Columbia Fire & EMS, 2000.

Unknown to Truck 4, these windows had been left open by the exiting occupants. Truck 4B (two person team from Truck 4) returned to their apparatus for a ladder to access the roof from Side C. Rescue 1 arrived at 00:26 and reported to Side C after being advised by the male occupant that everyone was out of the involved unit (this information was not reported to Command). Rescue 1 and Truck 4 observed inward air track (smoke and air) at the exterior basement doorway on Side C and an increase in the size of the flames from burning material on the floor.

Engines 26 and 10 encountered thick smoke and moderate temperature as they advanced their charged 1-1/2″ (38 mm) hoselines from the door on Side A towards Side C in an attempt to locate the fire. As they extended their hoselines into the living room, the temperature was high, but tolerable and the floor felt solid. It is important to note that engineered, lightweight floor support systems such as parallel chord wood trusses do not provide reliable warning of impending failure (e.g., sponginess, sagging), failure is often sudden and catastrophic (NIOSH, 2005; UL, 2009).

Prior to reaching Side C of the involved unit, Engine 17 found that their 350′ 1-1/2″ (107 m 38 mm) hoseline was of insufficient length and needed to extend the line with additional hose.

Engine 12, the fourth arriving engine, picked up Engine 17′s line, completed the hoselay to a hydrant on Banneker Drive (see Figure 2). The crew of Engine 12 then advanced a 200′ 1-1/2″ (61 m 38 mm) hoseline from Engine 26 through the front door of the involved unit on Side A and held in position approximately 3′ (1 m) inside the doorway. This tactical action was contrary to department procedure, as the fourth due engine has a standing assignment to stretch a backup line to Side C.

Rescue 1′s B Team (Rescue 1B) and a firefighter from Truck 4 entered the basement without a hoseline in an effort to conduct primary search and access the upper floors via the interior stairway. Engine 17 reported that the fire was small and requested that Engine 17 apparatus charge their line.

Questions

Consider the following questions related to the interrelationship between strategies, tactics, and fire behavior:

1. Based on the information provided to this point, what was the stage of fire development and burning regime in the basement when Engine 26 entered through the door on Floor 1, Side A? What leads you to this conclusion?
2. What impact do you believe Truck 4′s actions to open the Basement door on Side C will have on the fire burning in the basement? Why?
3. What is indicated by the strong inward flow of air after the Basement door on Side C is opened? How will this change in ventilation profile impact on air track within the structure?
4. Did the companies at this incident operate consistently with DC Fire & EMS SOP? If not, how might this have influenced the effectiveness of operations?
5. Committing companies with hoselines to the first floor when a fire is located in the basement may be able to protect crews conducting search (as outlined in the DC Fire & EMS SOP). However, what building factors increased the level of risk of this practice in this incident?

More to Follow

My next post will examine the extreme fire behavior phenomena that trapped Firefighters Phillips, Mathews, and Morgan and efforts to rescue them.

Remember the Past

This week marked the anniversary of the largest loss of life in a line-of-duty death incident in the history of the American fire service. Each September, we stop and remember the sacrifice made by those 343 firefighters. However, it is also important to remember and learn from events that take the lives of individual firefighters. In an effort to encourage us to remember the lessons of the past and continue our study of fire behavior, each month I include brief narratives and links to NIOSH Death in the Line of Duty reports and other documentation in my posts.

September 9, 2006
Acting CAPT Vincent R. Neglia
North Hudson Regional Fire & Rescue Department, NJ

Captain Neglia and other firefighters were dispatched to a report of fire in a three-story apartment building in Union City. Upon their arrival at the scene, firefighters found light smoke and no visible fire. Based on reports that the structure had not been evacuated, Captain Neglia and other firefighters entered the building to perform a search. Due to the light smoke conditions, Captain Neglia was not wearing his facepiece.

Captain Neglia was the first firefighter to enter an apartment. Conditions deteriorated rapidly as fire in the cockloft broke through a ceiling . Captain Neglia was trapped by rapid fire progress and subsequent collapse. Other firefighters came to his aid and removed him from the building. Captain Neglia was transported to the hospital but later died of a combination of smoke inhalation and burns.

NIOSH did not investigate and prepare a report on the incident that took the life of Captain Neglia.

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

National Institute for Occupational Safety and Health (NIOSH). (2005). NIOSH Alert: Preventing Injuries and Deaths of Fire Fighters Due to Truss System Failures. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

This series of posts focused on Understanding Flashover has provided a definition of flashover; examined flashover in the context of fire development in both fuel and ventilation controlled fires; and looked at the importance of air track on rapid fire progression through multiple compartments. To review prior posts see:

• Myths and Misconceptions
• Myths and Misconceptions: Part 2
• The Ventilation Paradox
• The Importance of Air Track

This post begins study of an incident that resulted in two line-of-duty deaths as a result of extreme fire behavior in a townhouse style apartment building in Washington, DC. This case study provides an excellent learning opportunity as it was one of the first times that the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) and Smokeview were used in forensic fire scene reconstruction to investigate fire dynamics involved in a line-of-duty death. Data development of this case study was obtained from Death in the line of duty, Report 99-21 (NIOSH, 1999), Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999 (District of Columbia (DC Fire & EMS, 2000), and Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999 (Madrzykowski & Vettori, 2000).

The Case

In 1999, two firefighters in Washington, DC died and two others were severely injured as a result of being trapped and injured by rapid fire progress. The fire occurred in the basement of a two-story, middle of building, townhouse apartment with a daylight basement (two stories on Side A, three stories on Side C).

Figure 1. Cross Section of 3146 Cherry Road NE

The first arriving crews entered Floor 1 from Side A to search for the location of the fire. Another crew approached from the rear and made entry to the basement through a patio door on Side C. Due to some confusion about the configuration of the building and Command’s belief that the crews were operating on the same level, the crew at the rear was directed not to attack the fire. During fireground operations, the fire in the basement intensified and rapidly extended to the first floor via the open, interior stairway.

Building Information

The unit involved in this incident was a middle of row 18′ x 33′ (5.6 m x 10.1 m) two-story townhouse with a daylight basement (see Figures 1 and 3). The building was of wood frame construction with brick veneer exterior and non-combustible masonry firewalls separating six individual dwelling units. Floors were supported by lightweight, parallel chord wood trusses. This type of engineered floor support system provides substantial strength, but has been demonstrated to fail quickly under fire conditions (NIOSH, 2005). In addition, the design of this type of engineered system results in a substantial interstitial void space between the ceiling and floor as illustrated in Figure 2.

Figure 2. Parallel Chord Truss Construction

Note: This is not an illustration of the floor assembly in the Cherry Road Townhouse. It is provided to illustrate the characteristics of wood, parallel chord truss construction.

The trusses ran from the walls on Sides A and C and were supported by steel beams and columns at the center of the unit (See Figure 3). The basement ceiling consisted of wood fiber ceiling tiles on wood furring strips which were attached to the bottom chord of the floor trusses. Basement walls were covered with gypsum board (sheetrock) and the floor was carpeted. A double glazed sliding glass door protected by metal security bars was located on Side C of the basement, providing access from the exterior. Side C of the structure (see Figure 3) was enclosed by a six-foot wood and masonry fence. The finished basement was used as a family room and was furnished with a mix of upholstered and wood furniture.

The first floor of the townhouse was divided into the living room, dining room, and kitchen. The basement was accessed from the interior via a stairway leading from the living room to the basement. The door to this stairway was open at the time of the fire (see Figures 1 and 3). The walls and ceilings on the first floor were covered with gypsum board (sheetrock) and the floor was carpeted. Contents of the first floor were typical of a residential living room and kitchen. A double glazed sliding glass door protected by metal security bars similar to that in the basement was located on Side C of the first floor. An entry door and double glazed kitchen window were located on Side A (see Figure 3). A stairway led to the second floor from the front entry. The second floor contained bedrooms (but was not substantively involved in this incident). There were double glazed windows on Sides A and C of Floor 2.

Figure 3. Plot and Floor Plan-3146 Cherry Road NE

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 18 & 20. District of Columbia Fire & EMS, 2000; Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 12-13, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology, and NIOSH Death in the Line of Duty Report 99 F-21, 1999, p. 19.

Figure 4. Side A 3146 Cherry Road NE

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 17. District of Columbia Fire & EMS, 2000 and Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 5, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology.

Figure5. Side C 3146 Cherry Road NE

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 19. District of Columbia Fire & EMS, 2000 and Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 5, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology.

The Fire

The fire originated in an electrical junction box attached to a fluorescent light fixture in the basement ceiling (see Figures 1 and 3). The occupants of the unit were awakened by a smoke detector. The female occupant noticed smoke coming from the floor vents on Floor 2. She proceeded downstairs and opened the front door and then proceeded down the first floor hallway towards Side C, but encountered thick smoke and high temperature. The female and male occupants exited the structure, leaving the front door open, and made contact with the occupant of an adjacent unit who notified the DC Fire & EMS Department at 0017 hours.

Questions

It is important to remember that consideration of how a fire may develop and the relationship between fire behavior and your strategies and tactical operations must begin prior to the time of alarm. Assessment of building factors and fire behavior prediction should be integrated with pre-planning.

1. Based on the information provided about the fire and building conditions, how would you anticipate that this fire would develop?
2. What concerns would you have if you were the first arriving company at this incident?

More to Follow

My next post will examine dispatch information and initial tactical operations by first alarm companies.

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

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