U.S. Fire Administration/Technical Report Series

Massive Leak of Liquefied 

Chlorine Gas

Henderson, Nevada

USFA-TR-052/May 1991

U.S. Fire Administration Fire Investigations Program

T

he U.S. Fire Administration develops reports on selected major fires throughout the country. 

The fires usually involve multiple deaths or a large loss of property. But the primary criterion 

for deciding to do a report is whether it will result in significant “lessons learned.” In some 

cases these lessons bring to light new knowledge about fire--the effect of building construction or 

contents, human behavior in fire, etc. In other cases, the lessons are not new but are serious enough 

to highlight once again, with yet another fire tragedy report. In some cases, special reports are developed to discuss events, drills, or new technologies which are of interest to the fire service.

The reports are sent to fire magazines and are distributed at National and Regional fire meetings. The 

International Association of Fire Chiefs assists the USFA in disseminating the findings throughout the 

fire service. On a continuing basis the reports are available on request from the USFA; announcements of their availability are published widely in fire journals and newsletters.

This body of work provides detailed information on the nature of the fire problem for policymakers 

who must decide on allocations of resources between fire and other pressing problems, and within 

the fire service to improve codes and code enforcement, training, public fire education, building 

technology, and other related areas.

The Fire Administration, which has no regulatory authority, sends an experienced fire investigator 

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during the event or even immediately after, but rather after the dust settles, so that a complete and 

objective review of all the important aspects of the incident can be made. Local authorities review 

the USFA’s report while it is in draft. The USFA investigator or team is available to local authorities 

should they wish to request technical assistance for their own investigation.

This report and its recommendations were developed by USFA staff and by TriData Corporation, 

Arlington, Virginia, its staff and consultants, who are under contract to assist the USFA in carrying 

out the Fire Reports Program.

The USFA greatly appreciates the cooperation received from Fire Chief William Bunker of the Clark 

County Fire Department, as well as Assistant Fire Chief Tom Alexander and Public Information Officer 

Robert Leinbach of his staff, and also Battalion Chief William Kourim of the City of Henderson Fire 

Department. Information was also provided by Cathleen Faulx, Emergency Management Coordinator 

of the Clark County Emergency Preparedness Office and Plant Manager Clifford H. Barr of Pioneer 

Chlor Alkali Company, Inc.

For additional copies of this report write to the U.S. Fire Administration, 16825 South Seton Avenue, 

Emmitsburg, Maryland 21727. The report is available on the Administration’s Web site at http://

www.usfa.dhs.gov/

Massive Leak of Liquefied Chlorine Gas

Henderson, Nevada

Reported by: J. Gordon Routley

This is Report 052 of the Major Fires Investigation Project conducted

by TriData Corporation under contract EMW-90-C-3338 to the United

States Fire Administration, Federal Emergency Management Agency.

Department of Homeland Security

United States Fire Administration

National Fire Data Center

U.S. Fire Administration

Mission Statement

As an entity of the Department of Homeland 

Security, the mission of the USFA is to reduce life and economic losses due to fire 

and related emergencies, through leadership, advocacy, coordination, and support. 

We serve the Nation independently, in coordination with other Federal agencies, 

and in partnership with fire protection and 

emergency service communities. With a 

commitment to excellence, we provide public education, training, technology, and data 

initiatives.

TabLe of ConTenTs

OVERVIEW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

SUMMARY OF KEY ISSUES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

LOCATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ORIGIN OF THE LEAK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

EMERGENCY RESPONSE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

STRATEGIC CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

EXPANDING GAS CLOUD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

EVACUATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

LEAK CONTROL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

LESSONS LEARNED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Appendix A: Chlorine Leak Incident Area Map, Pioneer Chlor Alkali Facility, 

and Diagram of Leak Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Appendix B: Technical Articles on Chlorine and Dealing with Chlorine Emergencies. . . . . . 13

1

Massive Leak of Liquefied Chlorine Gas

Henderson, Nevada 

May 6, 1991

Local Contacts: William Bunker, Fire Chief

Tom Alexander, Assistant Fire Chief

Robert Leinbach, Public Information Officer

Clark County Fire Department

575 East Flamingo Road

Las Vegas, Nevada 89119

(702) 455-7311

Cathleen Faulx, Emergency Management Coordinator

Clark County Emergency Preparedness

225 Bridger Avenue

Las Vegas, Nevada 89155

William Kourim, Battalion Chief

City of Henderson Fire Department

239 Water Street

Henderson, Nevada 89015

(702) 565-2307

Clifford H. Barr, Plant Manager

Pioneer Chlor Alkali Company, Inc.

8000 Lake Mead Drive

Henderson, Nevada 89015

(702) 565-8781

OVERVIEW

A massive leak of liquefied chlorine gas created a dangerous cloud of poison gas over the city of 

Henderson, Nevada, in the early morning hours of May 6, 1991. Over 200 persons were examined 

at a local hospital for respiratory distress caused by inhalation of the chlorine and approximately 30 

were admitted for treatment. Approximately 700 individuals were taken to shelters. It is estimated 

that from 2,000 to 7,000 individuals were taken elsewhere.
2 U.S. Fire Administration/Technical Report Series

SUMMARY OF KEY ISSUES

Issues Comments

Situation Chlorine release caused by leak of brine from heat exchanger mixing with liquefied gas. Mixture 

created corrosive acid which ate through pipes when product was transferred from storage tank. 

Leak increased as acid ate larger hole in pipe.

Delayed Alarm Plant employees believed they could contain the leak. Fire department notified by passer-by 

who was unsure of source. Response delayed until second call provided additional information. Further delay caused by long response distance and several possible sources to check for 

hazardous materials (Hazmat) release.

Jurisdiction Plant is located in Clark County island surrounded by the City of Henderson. Population at risk 

primarily in city. Agencies work together effectively.

Injuries Firefighters and plant personnel overcome when chlorine cloud moved in unexpected direction. 

Command post had to be relocated three times to avoid moving cloud. Some residents exposed 

during evacuation; over 200 examined at hospitals; 30 admitted.

Evacuation Citizens evacuated as leak continued to expand and control efforts proved unsuccessful. 

Approximately 700 people taken to shelters; 2,000 to 7,000 taken elsewhere. Police officers 

assisting with evacuation and traffic control exposed to gas cloud.

Control Measures Corroded valve allowed product to flow. Fire department Hazmat team and plant personnel 

entered together to stop flow. First attempt to stop flow by inserting blank flange was unsuccessful; Teflon-coated plate had to be used because of rapid corrosion of steel.

Extent of Leak Approximately 70 tons of chlorine escaped. Cloud dissipated with morning heat and winds.

LoCaTIon

The Pioneer Chlor Alkali facility is located in an industrial area, approximately 10 miles southeast of 

Las Vegas, Nevada. It is one of several chemicals and materials processing facilities that are located 

in the Basic Management Inc. complex. When the BMI complex was established, during World War 

II, it was located in the desert, several miles from any existing populated areas. Henderson was 

established nearby as a support community for the industries that were located in the complex. 

The Las Vegas metropolitan area has experienced rapid growth during the last decade and the City 

of Henderson has become a heavily populated suburb with more than 60,000 residents. The BMI 

complex currently occupies an unincorporated “island” under the jurisdiction of Clark County and 

is almost completely surrounded by the incorporated City of Henderson.

Public concern with the materials that are produced and stored in the BMI complex has created pressure to relocate the complex, away from populated areas. Several Hazmat incidents have occurred 

in the immediate area, including an explosion of ammonium perchlorate at an adjacent facility in 

1988, which resulted in two deaths and 372 injuries that included 15 firefighters. The most recent 

incident occurred while the Nevada State Legislature was considering a bill to require the complex to 

be relocated to an isolated area, approximately 15 miles north of Las Vegas. (For a detailed description of the earlier incident, refer to Report 021 of this series, “Fire and Explosions at Rocket Fuel 

Plant, Henderson, Nevada.”)
USFA-TR-052/May 1991 3

O

Pioneer Chlor Alkali produces chlorine gas through the electrolysis of sodium chloride (table salt). 

The chlorine is used primarily for water treatment and is shipped to clients in railroad tank cars and 

highway tank trucks. By-products of the process, including hydrogen gas and sodium hydroxide, are 

used by other companies in the BMI complex. The chlorine is compressed and stored as a liquefied 

gas in a bank of eight storage tanks, each of 150-ton capacity. The system has a storage capacity of 

approximately 1,200 tons, although company officials indicate that their policy is to limit the storage 

on hand to 300 tons or less.

Chlorine (Cl2

)

Molecular Weight 70.9

Boiling Temperature 20 degrees Fahrenheit

Immediate Danger to Life or Health 30 parts per million (ppm)

Short Term Exposure Limit 3 ppm

Expansion Ratio (Liquid to Gas) 450-500

The liquefied chlorine is stored in tanks at a pressure of approximately 50 pounds per square inch 

(psi) and temperature of approximately 30 degrees Fahrenheit. The chlorine is dried in the process of compression and, when dry, is noncorrosive. If it is contaminated by water or water vapor, 

hydrochloric acid is produced and the resulting product is extremely corrosive. It is believed that a 

tube failure in a heat exchanger allowed water to mix with the chlorine going into one of the storage 

tanks. When workers began to transfer the contents of that tank to a railroad tank car, the corrosive 

liquid began to rapidly deteriorate the steel piping system.

The leak was first detected by automatic monitoring equipment, located near the storage tanks, 

at approximately 0110 hours. Employees responding to the alarm found a pinhole-size leak in a 

2-inch elbow, located on a catwalk level approximately 10 feet above ground. The leak was a few feet 

beyond the valve on the discharge side of the pump which was used to transfer the liquid from the 

storage tanks to the rail car loading rack.

Attempts were made by plant personnel to stop the flow and patch the leak. The pump was shut 

down and the discharge valve was closed to stop the flow from the storage tanks to the leaking pipe. 

Management personnel were notified and members of the company’s emergency team were called to 

respond to the plant. At this time the leak was considered to be minor and employees believed that 

it could be controlled without causing a major hazard to the plant or the surrounding area.

Plant employees were considered to be proficient in handling situations of this type. The Chlorine 

Institute, a trade association of companies involved in the manufacturing, distribution, and use of 

chlorine and related products, coordinates a system of mutual-aid emergency response teams. These 

CHLOREP teams are made up of member company employees who are trained and equipped to 

respond to emergency incidents involving chlorine. Pioneer Chlor Alkali operates the CHLOREP 

team for Southern Nevada and surrounding areas and the emergency response team equipment is 

stored within its facility. Joint training exercises had been conducted with the Clark County Fire 

Department Hazmat Team and other area fire departments.
4 U.S. Fire Administration/Technical Report Series

E

At approximately 0150 hours a citizen notified Henderson Police Department that she had encountered a strong offensive odor when passing near the BMI complex on a major highway. The highway passes within one half mile of the complex, and the caller was concerned that there could 

be a release coming from one of the occupancies. The call was relayed to the Las Vegas City Fire 

Department Communications Center, which provides communications for the Clark County Fire 

Department. Since reports of odors in the area are a frequent occurrence, the Clark County Battalion 

Chief was notified, and he made the decision to wait for a more positive report of an incident before 

responding. The communications personnel began to call the industries in the area to ask if any of 

them had a problem.

At approximately 0200 hours a second call was received, this time by the Fire Communications 

Center, reporting a strong odor in the area. A full first alarm assignment was dispatched, including the Clark County Hazmat Team. The response time for the first units was 14 minutes due to 

the distance from the closest Clark County fire station. The first arriving units had some difficulty 

identifying which of several separate facilities was the source of the problem, until the odor was 

encountered. The odor was immediately recognized as chlorine, and the units were directed to the 

correct location.

Arriving at the gate of the Pioneer Chlor Alkali facility, the Clark County Battalion Chief found several 

employees who had been exposed to chlorine gas and were in need of medical attention. Employees 

reported that they were in the process of shutting down the plant and isolating the leak. They 

believed that the leak was successfully isolated and that they could handle the situation at that time.

Within a few minutes the atmosphere around the plant entrance became enveloped by the chlorine 

cloud and most of the plant employees donned their emergency escape respirators. The battalion 

chief requested assistance and ordered the area to be evacuated shortly before he and several other 

fire department members were overcome. All fire department and plant personnel evacuated to a 

location approximately one half mile uphill from the plant, where a command post was established. 

The Henderson Fire Department Battalion Chief, who had responded on mutual aid, assumed command and requested additional assistance, while the Clark County Battalion Chief and several other 

fire department members and plant employees were treated and transported to hospitals.

The Clark County Assistant Fire Chief responded from his home and assumed the duties of incident commander. He assigned the Henderson Battalion Chief, who was the most familiar with the 

area, as the operations chief in the incident command structure. The second arriving Clark County 

Battalion Chief was assigned to supervise the Hazmat group, due to his Hazmat team experience. 

Additional fire and medical units were directed to respond to a staging area adjacent to the command 

post. Liaison was also established with the Las Vegas Metropolitan and City of Henderson Police 

Departments at the command post.

S

Strategic decision making at this point focused on several factors:

1. Plant employees believed that the leak was isolated and would stop as soon as the residual chlorine had escaped from the piping system. The plant’s chlorine production had been shut down 

and the valve between the storage tanks and the leaking valve was closed. This would leave only 

the liquid that was already in the piping system that could leak out. They believed that the cor-
USFA-TR-052/May 1991 5

rosive liquid was eating away at the elbow, but that not more than 1,000 lbs. of chlorine could 

escape. Based on this information, there was no point in risking personnel to take additional 

leak control actions.

2. The population immediately at risk included only the adjacent industrial facilities, most of 

which were shut down and evacuated. One facility could not be shut down and a minimal crew 

was left to operate it, while wearing self-contained breathing apparatus (SCBA). These employees were trained in Hazmat procedures.

3. The use of water fog to accelerate vaporization or to absorb the vapors would have required the 

commitment of personnel and equipment in a hazardous area. Long hoselines would have been 

required to place master stream appliances in positions where they might be effective, and the 

acid produced by the combination of water and chlorine could have caused a greater damage to 

plant facilities and equipment.

4. At this point the situation appeared to be stable. Based on the strategic considerations, a 

cautious “wait and see” approach was taken and all personnel were kept out of the immediate area of the leak. Hazmat group members with monitoring devices were deployed in an 

attempt to define the location and track the progress of the gas cloud. City of Henderson 

officials assembled at the command post and maintained an immediate awareness of the 

situation. Additional resources were staged and precautions were taken, in case the situation 

changed and evacuation became necessary.

E

It was very difficult to accurately predict the size or travel of the gas cloud resulting from vaporization of the liquid pool on the ground. The flow rate of the leak could not be determined and the size 

of the resulting liquid pool could not be observed, since the storage tanks are surrounded by other 

processing equipment. The developing cloud could not be visually monitored due to the darkness 

and the location of the problem within the facility.

The heavier-than-air chlorine vapors have a tendency to move along the ground and concentrate in 

low spots. The BMI complex is located in a relatively high area and the terrain slopes down toward 

the north for several miles. A dry wash provided a low path for the heaviest concentration to migrate 

into a sparsely populated area north of the BMI complex. A growing cloud of lower chlorine concentration covered an expanding area along the ground. The wind was unusually calm and slowly 

pushed this cloud in the uphill direction, toward the command post and toward more populated 

areas to the east and west. Indications are that the gas cloud simply expanded under the cool and 

dry atmospheric conditions and moved slowly over the general area, while the amount of vaporized 

chlorine in the atmosphere continued to increase.

Weather Conditions:

Temperature 65 degrees Fahrenheit

Relative Humidity 15 percent

Wind 0-5 mph, variable direction

As time progressed it became evident that the chlorine cloud was continuing to grow. Subsequent 

investigation showed that the corrosive properties of the liquid had damaged the valve on the discharge side of the transfer pump, allowing a continuous supply of chlorine from the contaminated 
6 U.S. Fire Administration/Technical Report Series

storage tank to reach the leak. The leak also increased in flow rate, as the corrosive properties of the 

liquid ate a growing hole in the steel elbow. These factors created a pool of liquid, which allowed 

increasing quantities of chlorine to vaporize into the atmosphere. Before the leak was stopped an 

estimated 70 tons of liquefied chlorine gas escaped, making this one of the largest recorded leaks of 

this type in the United States.

E

At approximately 0330 hours conditions began to deteriorate rapidly. The command post and staging area were suddenly enveloped by the gas cloud and had to be evacuated. Although the command 

post was uphill from the plant, unusual wind conditions allowed the gas cloud to move along the 

ground and envelope the area without warning. The command post was relocated first to a convenience market parking lot, which also became untenable, and then to a race track parking lot, several 

miles from the source of the leak. Reports of strong odors in the occupied residential areas and 

downtown portions of Henderson caused the incident commander to begin evacuations of residents 

in affected areas.

At approximately 0345 hours a state of emergency was declared by the County Manager, and the 

Clark County Emergency Operations Center was activated. Preparations were made to provide temporary shelter for large numbers of evacuees, using designated schools and the many hotels and 

motels in the Las Vegas area. The Red Cross established temporary shelters in predesignated schools, 

while the Convention and Visitors Bureau began to notify its members of the situation.

The large parking lot at the race track provided an area for assembling resources, in case larger scale 

evacuations were necessary. Fire, medical, police, and other resources from several jurisdictions were 

staged and organized to respond to changing conditions. The number of agencies and jurisdictions 

involved utilized a variety of radio systems and frequencies. This problem was somewhat resolved 

by the fact that most of the fire service command officers and some of the police officials had cellular 

phones in their vehicles and these were used to supplement radio communications. No specific serious problem was caused by these communications difficulties though the overall operation was not 

as smooth as it could have been if integrated radio communications systems had been available.

The Clark County School District made school busses available to the fire department and 50 offduty firefighters were called in to drive them. Each bus driver was provided with an SCBA, in case a 

contaminated area was encountered, and two teams were made up with full crews of SCBA-equipped 

firefighters standing by to take busses into contaminated areas to rescue residents in immediate 

danger. Police officers were assigned to notify residents in the predicted path of the cloud, while 

firefighters were assigned to areas where the presence of chlorine could be detected. An estimated 

2,400 residents were evacuated from their homes and from local businesses.

Monitoring of the gas cloud was continued by fire department Hazmat teams from Clark County, Las 

Vegas City, and Nellis Air Force Base, in addition to county and State environmental health personnel. 

Sampling tubes were used to measure the chlorine concentration at ground level, and the readings 

were plotted on a map to track and predict movement of the cloud. A police helicopter was assigned 

to visually track the movement of the cloud.

Most of the readings indicated concentrations that produced a strong odor and respiratory distress 

but were below levels immediately dangerous to the life and health of most persons. All hospitals in 

the metropolitan area were alerted to stand by for large numbers of patients, and approximately 250 

were examined in emergency rooms. Several police officers, who were exposed while evacuating 
USFA-TR-052/May 1991 7

residents, directing traffic, and performing other functions in the area, were among those patients. 

The majority of the patients recovered quickly when removed from the contaminated atmosphere. 

Individuals with asthma and other breathing problems were severely affected by even minor exposure to the gas and accounted for most of the hospital admissions.

St. Rose Dominican Hospital, in downtown Henderson, was located within the affected area, and a 

decision was made to leave the patients in the building with the air handling system set to recirculate the interior air. Air samples indicated that the ventilation system could maintain a safe interior 

atmosphere, in spite of the outside conditions. This was felt to be preferable to risking moving the 

patients outside into the contaminated atmosphere. A retirement home in the direct path of the gas 

cloud was evacuated.

LeaK ConTRoL

As the sun began to rise, the cloud became more visible and its extent could be estimated. Several 

square miles were blanketed with a greenish haze, sitting just above ground level. It became obvious that the leak was not controlled and that direct action would be needed to stop the flow. It was 

not known how much liquid had leaked out, but the amount that could potentially escape was now 

estimated at 100 tons or more. Consultation with plant personnel led to the conclusion that the leak 

could only be stopped by placing a blank flange in the line between the storage tank and the leaking 

elbow. An entry team was assembled, including both fire department and plant emergency personnel, to go in and insert the blank flange.

Note: A blank flange is a solid plate, cut to the appropriate size to fit between the two pieces of a flange pipe connection. To 

insert the blank flange, the bolts must be removed from the existing flanged connection and the plate inserted between the 

two halves. The bolts are then reinstalled and tightened.

The entry team dressed in Level B protective clothing and SCBA approached the area of the leak. They 

found that the hole in the pipe had expanded to approximately one-inch diameter and was producing a steady stream of liquid chlorine. The liquid had formed a pool from which the chlorine was 

vaporizing rapidly.

To install the blank flange it was necessary to work within two feet of the actual leak, under the 

spray of the leaking liquid. Plant employees performed the actual installation of the blank flange, 

backed-up by fire department members. The first attempt, at approximately 0630 hours, proved 

unsuccessful when the highly corrosive liquid damaged the steel plate before the bolts could be 

tightened. A second attempt was successful, at another flange location, using a Teflon-coated steel 

plate. The leak was stopped by approximately 0730 hours.

With the leak stopped, the problem began to diminish. The remaining cloud on the ground vaporized 

quickly and the vapor cloud began to dissipate under improving weather conditions. Over the next 

three hours the heat of the sun warmed the ground and provided buoyancy for the cloud, while a more 

normal wind condition helped to move it away from the populated area. By 1000 hours the cloud had 

dispersed completely and evacuees were allowed to return to their homes and businesses.

For the next 24 hours there was a continuing concern that more of the stored chlorine might have 

been contaminated with water and the corrosive mixture could be eating its way out of additional 

tanks and piping. The Clark County Fire Department Hazmat Team continued to stand by until 

sampling of the remaining storage concluded that the contaminated chlorine was contained in one 

storage tank and most of its contents had leaked out. Preparations were made to disassemble the heat 

exchanger where the problem was believed to have originated.
8 U.S. Fire Administration/Technical Report Series

Lessons LeaRneD

1. The problems associated with a high-risk occupancy in one jurisdiction, creating a problem in a different jurisdiction, present obvious challenges for emergency planning response 

agencies.

In this case the responding agencies worked well together, but the deficiencies of the regulatory 

and planning processes were a major focus of attention after the incident.

2. The Incident Command System (ICS) proved to be extremely effective in this incident, particularly in coordinating the efforts of several different agencies at the scene.

The ability to assign major responsibilities to command officers from different fire departments, without any problems, is evidence that the personnel are trained and prepared to operate 

effectively.

3. The lack of effective radio communications between agencies was a problem at this incident.

Cellular telephones were used very effectively to supplement public safety radio capabilities and 

proved to be reliable under these circumstances. In other situations cellular telephone service 

has been compromised by the number of persons trying to use the systems under emergency 

conditions and particularly the heavy use of the systems by news media personnel. The location and time of day may have been key factors in making the cellular network responsive in 

this incident. Note: Centel Cellular will block off communications allowing only emergency 

personnel phones to work if the system starts to overload.

4. The decision between evacuating residents and warning them to remain indoors, with windows and outside air inlets closed, is often critical.

In this case, it was considered more practical to keep patients inside the hospital than to expose 

them to the outside atmosphere. This took into consideration the susceptibility of the patients 

to chlorine exposure, the ability to exclude outside air from the ventilation system and the availability of medical personnel and equipment inside the hospital. Some area residents reported 

that they were notified to evacuate and were exposed to the chlorine cloud while waiting for 

busses to pick them up. The risk of exposure during evacuation may have been greater than the 

risk if they had remained indoors.

5. The use of busses operated by fire department personnel is a practical means to evacuate 

residents.

It is more feasible to have firefighters drive busses than to train bus drivers to use SCBA. It is 

equally difficult for firefighters using SCBA to convince residents to expose themselves to the 

outside atmosphere in order to evacuate, unless the residents are already in distress. The contingency plan, sending a crew of SCBA-equipped firefighters on a bus to enter and evacuate an area 

in immediate danger, is a practical innovation.

6. Police officers, who are not provided with or trained to use SCBA, were effective in evacuating areas ahead of the contamination, but could not function in the contaminated areas.

Several police officers who were assigned to traffic control or to assist with evacuation were 

exposed to the chlorine cloud and transported themselves to medical facilities for evaluation in 

the later stages of the incident.
USFA-TR-052/May 1991 9

7. Due to the relatively low concentration of chlorine in the gas cloud, in this case, the predominant medical condition was limited to short duration respiratory irritation.

Chlorine is detectable by odor at very low concentrations and is a respiratory irritant between 

3 and 30 ppm. Individuals with chronic respiratory problems, such as asthma, were quickly 

affected and accounted for most of the hospital admissions.

8. It proved to be extremely difficult to determine the size, shape, and movement of the 

chlorine cloud.

Helicopter observation was a valuable asset, particularly with increasing daylight. Ground sampling over large areas is difficult to coordinate and requires careful mapping to be effective. An 

attempt was made to predict dispersion of the chlorine using CAMEO (a computer model program), but complicated factors of terrain, slope, temperature, wind velocity, relative humidity, 

and an unknown rate of release made predictions extremely difficult.

9. The application of water to the vapor cloud was considered in this situation to accelerate 

the evaporation of the pooled liquid.

Conventional wisdom suggests that massive applications of water spray could absorb chlorine 

from the air, resulting in a dilute liquid solution. Chlorine has a low rate of solubility in 

water, and, with a large leak, there is a concern that applying less-than-sufficient volumes of 

water would create a corrosive fog. Applying water to a container of liquefied chlorine could 

heat the contents to their boiling temperature and cause the container to rupture. It is often 

difficult or impossible to estimate the flow and rate of vaporization from a leak to make such 

determinations.

10. The delay in notification of the fire department and other agencies indicates a problem with 

plant personnel and the established standard operating procedures at the facility.

A review of communications tapes reveals that no call was received by the police or fire departments for this incident from the facility. A private-sector ambulance provider had been requested 

to respond to transport plant employees who had been exposed to the chlorine gas.

11. While emergency procedures had been planned for the chlorine facility itself, there was no 

specific plan for notification or evacuation in the event of a chlorine leak or other emergency extending beyond the property line.

Due to the risk created by the chemical industries in the area, the need for emergency warning 

systems should be evaluated. This level of planning requires both private- and public-sector 

participation.

12. The fact that the incident occurred at the facility where the CHLOREP Team equipment was 

stored caused unusual problems.

Most of the equipment that could have most valuable in trying to secure the leak could not be 

reached because it was in the Hazmat area. This included the SCBA units normally used by the 

team members, which are of a different type from those used by area fire departments. Another 

chemical plant in the area was able to provide the needed SCBAs for the plant members on the 

entry team.
10

App
USFA-TR-052/May 1991 11

Appendix A (continued)
12 U.S. Fire Administration/Technical Report Series

Appendix A (continued)
13

App
14 U.S. Fire Administration/Technical Report Series

Appendix B (continued)
USFA-TR-052/May 1991 15

Appendix B (continued)
16 U.S. Fire Administration/Technical Report Series

Appendix B (continued)
USFA-TR-052/May 1991 17

Appendix B (continued)
18 U.S. Fire Administration/Technical Report Series

Appendix B (continued)
USFA-TR-052/May 1991 19

Appendix B (continued)
20 U.S. Fire Administration/Technical Report Series

Appendix B (continued)
USFA-TR-052/May 1991 21

Appendix B (continued)