Thursday, October 6, 2011

Waxahachie Fire – Lessons for Emergency Response Planners

The recent fire at the Magnablend chemical facility in Waxahachie, TX was an impressive spectacle that fortunately had relatively little lasting impact on the local community beyond the destruction of the facility. Even with the evacuation of some local schools and businesses there appears to have been little immediate danger to the community; due in large part to the efforts of local firefighters.

Emergency Planning

Any emergency planner with responsibility for preparing for a response to a fire at a chemical facility, from the facility to State level, should be reviewing the news reports, particularly the photo and video reports, to learn lessons that can be applied to their emergency planning process. It is always better to learn lessons from incidents in other jurisdictions than to have to learn them on the fly in a live incident.

The Facility

According to the Magnablend web site the ‘Texas Liquid Facility’ at Waxahache is a liquid blending facility with a 24,000 sq ft warehouse, 30 mixing tanks of up to 10,000 gallons, a 7 car rail spur and an indoor truck loading station. Since this is a custom chemical blend facility there will be a wide range of chemicals in the facility and the actual mix of chemicals will probably vary widely.

Aerial photographs of the incident from the local NBC affiliate show that the facility is relatively isolated with lots of open areas around the facility. The nearest facility to the plant is Navarro College, about 200 meters away from the buildings at the Magnablend facility. In this incident the college was upwind of the fire.

Spreading Flammable Liquids

There are lots of lessons to be learned from this fire but one of the most important is that water spreads chemical fires. Picture 19 of the 28 photos in the slide show on the NBC affiliate web site clearly shows the fire spreading upwind along a small water course between the burning facility and Navarro College. The lack of fire-fighting equipment in the picture shows that this particular flame front has gotten around the fire line.

There is an interesting video on YouTube® showing the fire following a flow of water out of one of the buildings on site. The water is clearly contaminated with some unidentified chemical. The water flows out of the building and within seconds the fire follows behind it. In this video the contaminated water flows under a parked ladder truck and the flames engulf the truck at the end of the video. The fire truck was probably destroyed.

Fighting Chemical Fires with Foam

The fact that water frequently spreads burning liquids is well known in the fire-fighting community. Many communities with large chemical facilities or fuel storage facilities have foam based fire-fighting equipment just because of this problem. To be effective fire-fighting foam must be applied to the liquid surface.

Unfortunately, with the fire in this instance being inside of a building this complicates the effective employment of foam. With foam being a relatively limited asset in most cases, fire-fighters will be reluctant to use it if it cannot be employed effectively if they have it available.

Why Use Water?

With the known problems of water spreading flaming liquids, why would fire departments still use water to fight a chemical fire? If foam cannot be employed effectively, the only other available alternative is to let the fire burn itself out; consuming the available flammable liquids. This tactic is frequently used at chemical storage facilities where there are isolatable large storage tanks on fire. This works well when the storage tank walls are intact or the tank is alone in a diked area that will contain the contents in case of a tank collapse.

The problem in a warehouse situation or a facility with lots of smaller tanks is that allowing the fire to burn out risks exploding containers sending flaming debris beyond the fire line. Each container; pails, drums, totebins and tanks; becomes a potential explosive device as flames heat the contents to their boiling point. With the exception of storage tanks, these containers do not typically have pressure relief devices so the pressure builds in the container until the container catastrophically fails producing an explosion.

Drums are a particular problem in this situation. Drums frequently fail where the side walls are joined to the base of the drum. This causes the drum body to launch like a rocket. Since many chemicals are easily ignitable at their boiling point, the drums fly through the air spewing fire from their base. Typically there are still flaming chemicals in the drum when it lands, a potential source for spreading the conflagration.

To prevent these dangerous explosions fire-fighters use water to keep the contents of the containers below their boiling point. Unfortunately this takes large quantities of water and ware houses are seldom diked to contain this amount of water; there are too many requirements for vehicles and materials to enter and leave the warehouse to make this practicable.

Emergency Planning

Every chemical facility is going to present a different hazard for fire-fighters. Frequently, those hazards will vary greatly from area to area within a given facility. Emergency planners need to take this into account when formulating their plan for responding to a fire at chemical facilities.

First and foremost there must be a formal emergency response planning effort made for every chemical facility, particularly those facilities with significant quantities or varieties of chemicals on site. Where fire-fighting foams will be needed to fight the chemical fires the type of foam must be identified and adequate quantities need to be readily available as does the equipment for its employment.

Where foam employment will not be practicable for one reason or another the decision process for deciding whether or not water will be employed needs to be identified in advance. The pros and cons need to be clearly identified so they can be weighed in the balance of the actual situation on the scene.

Finally, if the possibility of using water at chemical-facility fire exists then planners need to clearly analyze the run-off situation. Knowing that water flowing out of the facility will contain a mixture of chemicals; some of which will be flammable, toxic or both, planners need to ensure that they have a plan in place for containing the consequences of that run-off. And those consequences may include the spread of fire along the water flow.

1 comment:

Munros Safety Apparel said...

"It is always better to learn lessons from incidents in other jurisdictions than to have to learn them on the fly in a live incident.".

Couldn't agree more! Every incident (regardless of the outcome) has teaching potential. What went right? What went wrong? Where did it go wrong? Understanding past situations gives you the chance to better handle a similar situation should it arrive.

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