40 years on from the San Juanico disaster – What happened and what have we learnt?

Site: LPG (Liquid Petroleum Gas) storage and distribution centre in San Juan Ixhuatepec, 20km north of Mexico City owned by PEMEX State Oil Company.

Incident: LPG explosions causing large blast waves, fires and extensive damage

Fatalities: 600 fatalities with the majority being the public

Consequences: 7,000 injuries, up to 200,000 people evacuated from their homes and the whole terminal and nearby houses destroyed.

What happened?

At approximately 5.30am on 19th November 1984 there was a major fire and series of explosions at a LPG (Liquid Petroleum Gas) storage and distribution centre in San Juan Ixhuatepec, 20km north of Mexico City. There were approximately 600 fatalities (majority from severe burns or from being inside collapsed or damaged buildings), approximately 7,000 injuries, 200,000 people were evacuated, and the terminal was destroyed. The blasts were recorded on a seismometer 20 km (12.4 miles) away, and the largest blast registered 0.5 on the Richter scale. Most of the injuries and fatalities were in the surrounding community –people were living as close as 130 m (425 ft.) from the terminal. The disaster began with an initial leak of LPG from one of the LPG storage tanks which formed a large vapour cloud and found an ignition source at the plant’s flare pit. This ignition generated a series of massive explosions in the surrounding LPG tanks. They generated fire balls and shockwaves that destroyed nearby homes and structures. Some estimates suggest the fireballs reached 300 meters high. The heat generated from the fireballs caused a BLEVE (Boiling Liquid Expanding Vapour Explosion) on the nearby tanks which caused these to rupture and explode. This caused a chain reaction and several tanks over several hours exploded in this way leading to lots of debris flying like deadly missiles into the town and eventually destroying the town and multiple people.

Figure 1: Image taken during the aftermath of the explosion. Reference: Forty Years After San Juan Ixhuatepec: How One Industrial Disaster Still Haunts Latin America – LatinAmerican Post

Figure 2: Image taken after the explosion. Reference: Microsoft PowerPoint – 2014-10-Beacon.pptx

Why did it happen?

The San Juanico disaster occurred due to a combination of technical failures, inadequate safety measures and hazardous urban planning. The failures are highlighted below:

• The initial leak of LPG was likely due to a failure in the pipeline system, valve or tank structure which allowed a large quantity of LPG to leak forming the vapour cloud. The exact cause of the leak is not known but likely due to aging infrastructure, insufficient maintenance or mechanical failure.
• The facility did not have adequate safety mechanisms to detect gas leaks or contain the initial fire which allowed the gas leak to spread. There was limited equipment in place such as effective cooling systems to reduce tank temperatures during the fire to prevent the BLEVE (Boiling Liquid Expanding Vapour Explosion).
• The LPG storage was also stored in large amounts and in close proximity to each other without adequate spacing between the tanks. This design allowed the chain reaction effect of multiple explosions across the site. There was also inadequate fire barriers or protection enclosures to contain or limit the spread of the fires/explosions between the tanks.
• Over time, the urban development had expanded to around the site which placed thousands of residents around the hazardous site and putting them at increased risk. The zoning regulations were limited 40 years ago.
• Insufficient emergency response to the incident lead to more lives being lost and due to lack of contingency plans and infrastructure the evacuation and medical assistance were not effective.

What can We Learn 40 years on?

The following can be learnt from this disaster 40 years on:

1. The Need for Proper Facility Location and Buffer Zones

• The San Juanico facility was situated dangerously close to residential areas. This disaster highlighted the importance of placing industrial facilities that handle hazardous materials far away from populated areas to reduce potential casualties in case of an accident.
• Establishing adequate buffer zones between industrial sites and communities can limit the impact radius of explosions or toxic releases and help protect residents.

2. Robust Safety Standards for Hazardous Storage

• The disaster underscored the importance of strict standards for the storage of volatile gases like LPG. Storage tanks must be designed to withstand pressures and potential hazards, with safety features like pressure relief valves and systems to prevent leaks.
• Regular safety audits, tank inspections, and updated safety infrastructure are critical to prevent failures, especially in high-risk facilities.

3. Implementation of Hazard Control Systems

• There were few effective hazard control mechanisms in place to prevent or mitigate the leaks and subsequent explosions at San Juanico. Facilities handling hazardous substances must have robust systems in place, such as:
  • Leak detection systems that provide real-time alerts for potential leaks.
  • Automatic shut-off systems i.e. ROSOV (Remotely operated shutoff valves) that can quickly contain leaks and prevent escalation.
  • Fire suppression systems designed specifically for the types of hazardous materials stored.

4. Comprehensive Risk Assessment and Safety Audits

• A detailed risk assessment could have identified potential hazards, such as overcrowding of storage tanks or lack of containment measures i.e. DSEAR risk assessment. This disaster demonstrated the necessity of conducting rigorous risk assessments, especially in facilities dealing with flammable or explosive materials.
• Regular safety audits and updates to risk assessments ensures that facilities can keep up with best practices and adapt to new risks or changes in their operational environment.

5. The Importance of Emergency Preparedness and Response

• Emergency response plans were either absent or inadequate in San Juanico, contributing to confusion and delays in evacuation and rescue efforts. A strong emergency response plan includes:
  • Evacuation plans and drills for workers and neighbouring communities.
  • Established communication protocols between facility operators, emergency responders, and local authorities.
  • Clear emergency contact information and accessible resources, such as community shelters and medical aid stations.
• Facilities and communities must regularly test and update their emergency procedures to ensure they are prepared for a wide range of scenarios.

6. Community Awareness and Education

• Many San Juanico residents were unaware of the dangers posed by the LPG facility and were unprepared for such a disaster. Educating communities about potential industrial hazards and emergency procedures is essential.
• Community awareness campaigns can include information about the types of hazards present, signs of danger (like gas leaks), and specific steps to take during an emergency. This can empower residents to act swiftly and safely in the event of an incident.

7. Strengthening Regulatory Oversight and Enforcement

• Weak regulatory oversight was a major factor in the disaster, as safety regulations and standards were insufficiently enforced. This incident emphasises the importance of strong regulatory frameworks that mandate compliance with safety standards.
• Regular inspections by regulatory authorities and independent audits help ensure that facilities adhere to best practices and maintain safe operating conditions.

8. Investing in Safety Training and Safety Culture

• Many of the workers and local emergency responders were not adequately trained to handle a large-scale LPG disaster. A comprehensive training program for employees on emergency response, hazard management, and risk awareness is crucial.
• Building a strong safety culture within companies handling hazardous materials encourages employees to prioritise safety, report potential hazards, and adhere to protocols.

9. The Role of Advanced Technology in Monitoring and Control

• San Juanico highlighted the importance of technological investments, such as automated monitoring systems, which could have detected leaks early and triggered preventive measures.
• Modern facilities benefit from real-time monitoring systems, predictive maintenance, and automated shutdown systems to respond swiftly to potential hazards.

10. Learning from Past Incidents to Prevent Future Disasters

• Industrial facilities worldwide can learn from the San Juanico disaster to prevent similar tragedies. Documenting the causes and responses to the disaster provides valuable insights into what went wrong and how to improve.
• Continuous improvement through learning from past incidents is essential for developing best practices, improving safety standards, and preventing future accidents.

Conclusion

The San Juanico disaster serves as a powerful reminder of the need for comprehensive safety and risk management practices in industries handling flammable materials. Key lessons include the importance of safe facility siting, stringent safety standards, effective emergency preparedness, regulatory enforcement, and community awareness. By applying these learnings, industries can minimise risks to workers, neighbouring communities, and the environment, helping to prevent such tragedies in the future. Finch can help support our clients with LPG and gas storage systems ensuring the design is appropriate and technology is used well to ensure a disaster like San Juanico doesn’t happen at their sites.