The Guadalajara 1992 Sewer Gas Explosion Disaster

The most vulnerable component of a municipal wastewater system to terrorist attack is the network of underground sewer lines that move wastewater from its origin to a treatment plant, according to a 2005 survey of experts. (1-3) Modern collection systems, which include sanitary, stormwater or dual-use collection lines, crawl for miles beneath busy city streets. Collection systems have multiple access points, including manholes, drains, and catch basins. Sewer lines vary from 4 inches to greater than 20 feet in diameter. Manholes are typically set 300 feet apart and provide ready vertical access to sewers below. (4) Authorities in the US worry that that terrorists could use these access points to covertly place incendiary devices or other weapons of mass destruction beneath a major population center.

The disastrous series of sewer gasoline explosions in Guadalajara on Wednesday, April 22, 1992, though not caused by a terrorist attack, demonstrate the potential impact of a well-planned and executed terrorist attack using a city’s sewer lines. The multiple blasts over a period of about four hours tore apart more than six miles of sewer lines and, in the worst-hit places, left heavily-trafficked streets in a pile of rubble sitting in 25-foot-deep sewer trenches. The explosions crushed to death 206 people; injured 1,460 people; damaged 1,148 buildings; and destroyed 350 businesses and 505 vehicles, according to one source (the numbers vary slightly from source to source). (5) In addition, the disaster left about 15,000 people homeless. (6) The political fallout rocked Mexico for years because local authorities knew of a gas leak problem for days but chose not to evacuate the population. Here we focus on a description of the immediate peri-impact time period.

Prelude to the April 22, 1992 Guadalajara Explosions

Mexico’s historic 475-year-old Guadalajara, the capital of Jalisco state, is located on a dry and arid mile-high plain 300 miles west of Mexico City. The city is named after Guadalajara, Spain, whose name, in turn, originates from the Moorish Arabic word Wad-al-hidjara, meaning “river running between rocks”. The population of Guadalajara, Mexico, is about 4 million (2005 estimate).

A few days before April 22, 1992, residents of the Reforma district in the heart of downtown Guadalajara began to notice a persistent odor reminiscent of gasoline and other chemical odors emanating from their toilets and drains. (7) At first, many residents ignored the odor, attributing it to the annual spring cleaning of the nearby gasoline storage facility called La Nogalera. Pemex (short for Petroleos Mexicanos), the state-owned oil monopoly, owned and operated La Nogalera.

The smell worsened by Sunday, April 19, 1992 (Easter Sunday in this deeply religious city) when many residents complained to the Guadalajara Fire Department and the Intermunicipal Water and Sewer System--Guadalajara’s greater metropolitan sewer authority (Sistema Intermunicipal de Agua Potable y Alcantarillado or SIAPA). By Tuesday, April 21, 1992, radio and local newspapers carried stories about the odors. The reason for the concern was the grim history of recent disasters associated with Pemex.

Pemex Petroleum and Prior Industrial Disasters

In October 1991 a small explosion in the sewer lines blew off sewer covers in Colonia Valled del Alamo, which is close to La Nogalera plant owned by Pemex. On November 19, 1984, an explosion in a Mexico City suburb killed about 500 people at the Pemex petroleum storage facility at San Juan Ixhuatepec. On March 25, 1983, three explosions in Guadalajara’s Independencia sewer line injured several people and damaged 38 buildings and 70 vehicles. At the time, the state attorney general and the director of Guadalajara’s SIAPA (see above) determined that the explosion resulted from gasoline leakage from a nearby Pemex facility into the sewer pipes. Pemex never acknowledged blame for the incident and was never held publicly accountable, but quietly moved money from its state account to another state account from which victims of the explosion received damages. (8) On June 3, 1979, an exploratory well owned by Pemex in the Gulf of Mexico, about 600 miles south of Texas, blew out, becoming the largest unintentional oil spill in history. (9)

Pemex was founded on March 18, 1938 as a state-owned monopoly following expropriation by Mexican leaders of the assets of 17 foreign oil companies operating in Mexico. In the 1970s, new sources of oil were discovered making Pemex the wealthiest entity in Mexico. Pemex has long been the single greatest source of public funds; for example, at the time of the 1992 sewer line explosions in Guadalajara, Pemex supplied the national government with a staggering 40 percent of its total revenues. (10-11) Critics contend that Pemex is corrupt and behaves as a “state within a state.” For example, Pemex regulates itself more or less because the resources at its disposal far outstrip the federal urban development and ecology agency Secretaria de Desarrollo Urbano y Ecologia (SEDUE).

Indeed, Pemex and many other companies in Mexico were accustomed to dumping hazardous wastes directly into municipal sewers, according to one source. A Mexican environmental consultant, Lilla Albert, claimed in the “early 1990s that even in Mexico City, where the deepest inroads into environmental regulation had been made, ‘at least 95.5 percent of the hazardous industrial wastes generated in the city are disposed of through the municipal wastewater system.’” (10-11) 

Prelude to Disaster—the Authorities Respond to Citizen Complaints

The Guadalajara Fire Department and SIAPA on Tuesday, April 21, 1992 visited the Reforma district neighborhood, the origin of the complaints about the odor, and confirmed that an alarming smell was rising up from the sewer drains. Because the odor smelled like gasoline, the firefighters and sewer authorities engaged the state civil defence unit and notified Pemex to assist in diagnosing the problem. The state civil defence unit, an element of the civil protection bureaucracy, was created after the catastrophic 1985 Mexico City earthquake to “prevent man-made disasters from occurring, to evacuate the population when disasters of any kind were imminent, and, when disasters did occur, to coordinate post-disaster rescue work and crowd control.” Since it was usually staffed by people “without much technical training, no one seemed to regard it as much of a player,” according to Varley. (12)

On the afternoon of Tuesday, April 21, 1992, Varley writes that “a roving brigade—made up of the local fire chief [Jose Trinadad Lopez Rivas], the SIAPA director and technical director, the local civil protection officer, technicians from Pemex, and a group of police officers” began to investigate the problem. (11) These staff members, according to one source, “checked the water discharge from the 18 de Marzo terminal, measured “explosivity” in the separating tank and discharge reading area, but found nothing [unusual]. Explosivity readings are based on the proportion of gaseous vapor in the air trapped in the sewer pipes.] SIAPA took samples of water at the plant outlets and made no mention of having found any irregularities. Pemex and SIAPA staff took samples at various points in the drain system and adjacent areas, in the areas between Refineria and Rio Reforma streets and Gante and 20 de Noviembre [streets]. The samples were forwarded to the State of Jalisco Centre for Research and Assistance in Technology and Design. They were found to contain the solvent hexane.” (13)

In addition, “[w]ater samples were taken from the sewer main at the corner of Analco and Gante streets. The water was clear and the water vapour had a typically solvent odor. The procedure was repeated at other manholes, with sampling between Rio Atotonilco and Tototlan avenues. On Doctor R. Michel Avenue concentrations of up to 100% explosivity were found. The suspected solvent appeared to be coming from…the La Central S.A. oil processing plant…It was reported that hexane was stored at this plant.” (13)

What does an explosivity measurement of 100% mean? It suggests the disquieting probability of imminent explosion set off by a spark or cigarette. Varley recalls that a technical consultant reportedly told a journalist the following: “When we see levels that high in the US, we run.” (7) The Pemex technicians fingered the cooking oil plant (La Central) because the acrid smell resembled hexane, which was stored in La Central but not at Pemex’s La Nogalera.

The local authorities turned their attention to La Central. Jesus Hernan Morales Doria, a member of the cooking oil company’s board of directors, responded by promptly shutting down the factory at midnight on April 21, 1992, denying his company’s involvement. Meanwhile the fire department opened a number of manhole covers to allow the alleged hexane gases to escape and flushed the drains with water to push the alleged hexane out of the city sewer pipes into the river outside of Guadalajara. The explosivity levels when remeasured declined from 100% to 15% by 3:30 a.m. on April 22, 1992. Believing they had solved the problem, the firefighters went home to bed. (14)

However, by 9 a.m., April 22, 1992, a nervous SIAPA director met with the Jalisco State Governor Guillermo Cosio Vidaurri and his state secretary of urban and rural development to discuss sewer explosivity levels, which were at 100% again. The governor later denied anyone had explained the gravity of the situation to him. Between 9 and 10 a.m., April 22, 1992, fire department and SIAPA officials in the neighborhood were still reassuring residents that there was nothing to worry about. At about 10:06 a.m., April 22, 1992 (the time of the first explosion noted by different observers varies by several minutes), the explosions began.

Disaster sociologist, BE Aguirre, and his colleagues published another version of the events leading up to the explosions, as follows: “For at least 12 hours prior to impact, neighbors were aware that they were in danger of a gasoline explosion. The day before the explosion the Fire Department cooperated with the Transit Police to cordon off part of the area (corner of Gante and Analco) that eventually exploded. At least one radio station had deployed personnel to the area endangered by the gasoline spill hours prior to the explosion. Red Cross and Fire Department personnel had been deployed the night prior to the explosion to the city blocks that were eventually destroyed. During their deployment they confirmed the presence of pressurized gasoline vapor columns spewing out of drainage manholes and of housewives who complained to them of the presence of gasoline in their toilets. The Red Cross treated a police officer, a fireman, and a worker from [Pemex] for gasoline inhalation. The day of the explosion a local newspaper had published the news of the presence of gasoline in the drainage system in its morning edition. The existence of these unofficial but nevertheless important cues of imminent danger probably meant that an unknown number of neighbors evacuated their homes prior to the explosion.” (15)

Devastation

The blasts measured 7.1 and 7.0 on the Richter scale at the University of Mexico in Mexico City some hundreds of miles away, according to one report. (16) The number of explosions is controversial. One source notes the following sequence of explosions:

i.   10:06 a.m.  Aldama-Gante-20 de Noviembre

ii.  10:10 a.m.  Gante-Calzada del Ejercito-Violeta

iii.  11:30 a.m.  Calzada del Ejercito-Rio Bravo

iv.  11:30 a.m.  Rio Nilo-Rio Suchiate

v.   2:20 p.m.    Rio Alamo-Rio La Barco-Gonzalez Gallo (16)

About 7 miles of sewer pipe exploded. The worst damage at the street level was at Gante and 20 de Noviembre streets. Varley explains that “Gante Street marked the northern edge of an industrial area and the southern edge of an old, tight-knit, densely populated and relatively poor neighborhood in Guadalajara called Analco, which sat above Guadalajara’s sewer main—a pipe 18 feet in diameter.” (14) When the pipe exploded, several city blocks were reduced to ravines containing 230,000 tons of rubble. The blast hurdled cars and busses in the air, some of which landed on nearby rooftops. Adults, children, and pets suddenly dropped out of site beneath the concrete rubble. Easter vacation explains in part the number of children victims who had been playing on the street.

I

Aguirre notes that the explosions were experienced by his interviewees as sudden and nearly simultaneous. People told him that the “only indication of warning [was]…people looking down the streets and seeing a rapidly disintegrating landscape advance towards them. Those who survived turned away from the center of the street where the drainage pipe that blew up was located. The explosion was described as a very loud hissing sound.” (15)

Responding to the Explosion

a. Search and Rescue

Aguirre and his colleagues in October 1992 interviewed 43 persons who had been buried alive, 22 volunteers who had participated in the direct rescue phase, and 5 Red Cross paramedics from the badly damaged Analco, Guadalajara, neighborhood. They found that neighbor volunteers living in Analco conducted most of the search and rescue activities. (15) Indeed, most of the people who were rescued alive in the aftermath of the tragedy were rescued by these volunteers.

Victims acted cooperatively during entrapment by providing information to rescuers about themselves and other people in the rubble. For example, a man and his two nephews were having breakfast in their home when the explosion buried them alive. The man was experiencing severe difficulty breathing. He could hear his two nephews and instructed them to synchronize their scream for help at his count of 3. Eventually people heard them and saved them. (15)

Another example (among many provided in the Aguirre article) was a mechanic who was protected by a heavy bench used in the shop. The bench landed on top of nearby metal engines, thus forming a cavity in the debris that buried him from the waist down. Two other people buried with him were talking to one another about the instability of the rubble and the need to tell searchers to pull them out simultaneously to avoid killing or injuring the one left behind. The point is that people were actively participating in their rescue. (15)

During the first 45 minutes or so after the explosions “the people at the center of these search and rescue formations also extracted the victims, and they, or other volunteers, would transport them in private automobiles to places where the victims could receive medical treatment. However, once Red and Green Cross and other medical personnel arrived at the scene of the disaster, they ceased doing so, and paramedics would carry out the actual removal and transportation of the victims. During the initial phase of the response, simple, hand held, small mechanical tools [heavy gloves, ropes to wrap around searchers as they entered dangerous places, lumber, wire cutters, metal buckets to remove sand and loose earth, metal bars to remove heavy objects, and heavy hoes] were most effective in helping people do their rescue work,” noted Aguirre. (15)

Interviewees spontaneously volunteered their concern about the use of heavy earth-removing equipment, which “was moved into the impacted zone very quickly, in places two hours after impact, and that human remains were dug out of the rubble by these machines as they excavated. [In one case] the neighbors of a block, led by the bereaved father of a boy then missing, successfully blocked the use of heavy machinery in it. The prevailing feeling [was] that in many of these instances the machines actually killed people who were buried alive. The generalized belief accounting for their use [was] that…public officials [were trying to] cover up the extent of the explosion.” (15) The heavy machinery was nearby because of a large public works project (a light rail system) close to Analco. “Reportedly, the labor force working on this massive project was ordered into the impacted area by the engineers in charge of the project for the [well-intentioned] purpose of helping the neighbors,” explained Aguirre.

b. Communication

The city’s two major radio station corporations immediately after the explosions ceased normal operations, and for two days “helped structure the societal response to the explosion. [One corporation] owned five radio stations throughout the city, which were reformed into a network. Their transmission power was supplemented by seven radio field stations donated temporarily by a major local manufacturing firm. These seven field stations were positioned in key places throughout the city, such as the Red Cross, the morgue, the local stadium where the homeless had congregated, and the hospital where many of the victims were receiving treatment. The field radio stations were manned by volunteers under the supervision of professional staff of the corporation. They helped the public in finding the whereabouts of lost persons and of needed supplies.” (15)

c. Medical Care

Some of the rescuers were medical doctors and nurses. The Jalisco government and the University of Autonomous of Guadalajara (UAG) Medical School requested that two American emergency physicians, Drs. James Dugal and Gail Anderson, lead their team of physicians (the American Medical Search and Rescue Team based in Atlanta, Georgia) to Guadalajara to evaluate the search and rescue efforts, the medical needs of the trauma hospitals, and provide consultation on the “crush syndrome”. (16) Dr. Dugal describes the scene as follows:

“The blast blew open the streets and carved an enormous 9 mile ditch down the middle of Avenida Gante measuring 80 feet wide and 25 feet deep. Approximately 1,000 buildings were collapsed, destroyed or heavily damaged…Initial reports by the Mexican Government and confirmed by team member Al Nixon of the Atlanta Red Cross said at least 2,000 people were injured, 200 people were killed and over 20,000 were left homeless. Damages of building were estimated to be at $300 million.

“Upon arriving to Guadalajara, the team ‘hit the ground running’. One hour after arriving on Friday [April 25, 1992], Dr. Dugal and the rescue team were peering into a massive crater in what used to be the street, assisting in the digging for survivors of one of the worst industrial accidents in Mexican history. The team began assisting in the search and rescue effort which would last the entire night. The methods of the rescuers were limited due to the lack of specialized equipment. Shovels and picks would break under the weight of the layers of concrete. The feelings of ‘helplessness’ would be suppressed for a short time when the rescue team would discover a potential survivor.

“The next morning, Drs. Dugal and Anderson met with Dr. Jesus Castillo, Director of the Program of Medicine for UAG [Universidad Autonoma de Guadalajara] Medical School and Dr. Leone Solis, Director of UAG Medical School. Dr. Castillo was responsible for the Disaster Field Hospital and the triage of the injured to the trauma hospitals. Dr. Solis was responsible for hospital coordination of trauma patients. Dr. Castillo also coordinated the rescue effort during the 1988 Mexico City Earthquake. “Dr. Castillo briefed Drs. Dugal and Anderson on the status of the search and rescue effort and the medical needs of the hospitals. The UAG medical school had provided physicians, nurses, medical supplies, food and clothing for over 10,000 injured or homeless in the disaster area.

“Dr. Castillo commented that the supplies provided such as tetanus toxoid, general antibiotics and orthopedic supplies were being consumed at a rapid rate. Not only were they treating patients at the field hospital from the explosion but the physicians were treating patients with daily problems such as hypertension, diabetes, seizures and general pediatric complaints. While Drs. Dugal and Anderson were participating in the treatment of patients in the field and the trauma hospitals with “Crush Syndrome,” they created a “wish list” of critically needed medical items. Orthopedic supplies, Antibiotics, Intravenous fluids, Central Venous Lines, Swan Ganz lines and Tetanus Toxoid were considered immediate needs and the request was sent back to Atlanta, Georgia, American Medical Search and Rescue Team headquarters.” (16)

Cause(s) of the Sewer Explosions

Pemex initially declared itself blameless for the blast, still insisting the cooking oil company was to blame. But La Central was able to clear its name. “Chemical engineers agreed that an explosion of this magnitude would have required hundreds of thousands of liters of hexane in the sewer. La Central explained that it handled less than 3000 liters of hexane a day, and had a maximum storage capacity of 60,000. What’s more, La Central’s hexane tank was still full after the explosion—and La Central itself was fully intact. Chemical engineer Alejandro Villasenor told a Proceso reporter that if La Central had, in fact, been the source of the leak, the factory would have been the first place to explode.” (17)

Meanwhile, astute reporters covering the explosions took note of a huge search party looking for a gasoline leak at La Nogalera, the Pemex gasoline storage facility. On April 23, 1992, Pemex announced detection of a leak the previous day somewhere on its southern gasoline pipe line from Salamanca, and had shut off the pumping station on this line at noon on April 22, 1992. In the afternoon of April 23, 1992, Pemex announced the location of the leak in a 12-inch pipe about 3,300 feet from La Nogalera. This so-called “Alamo Industrial” area—mixed residential and industrial buildings—had already been evacuated on the afternoon of April 22, 1992, by authorities when they received the new Pemex information.

Pemex called in international experts to help get the leak under control, contending that the explosions caused the leak, rather than the other way around. By April 24, 1992, it had become clear that “an extraordinary amount of gasoline had escaped. By one estimation, the underground soil was saturated with a meter-thick [three feet] blanket of the fuel covering 16 square blocks near La Nogalera.” (17) A commission of 18 federal congressmen traveled to Guadalajara to assess the situation but was denied access to La Nogalera. Pemex workers admitted privately that they were forbidden to talk about the situation to outsiders.

Open Questions and Theories

In the absence of information, people theorized about a number of observations. Why had the explosivity readings increased after having dropped during the night before the explosions? They surmised that the cool temperatures caused the gasoline to move more to the liquid state, thus evading detection by the vapor-reading explosimeters. Another theory was about the possible contribution of work on the light rail construction to the explosions. Perhaps the city diverted sewer pipes with a series of angular turns and that these turns had created a “stopper”, backing up gases in the system.

A third theory was that “Pemex workers had been embezzling gasoline via the La Nogalera facility and had learned that the attorney general’s office was just about to inspect the facility. Fearful of being caught with an oversupply of gasoline…[they] dumped the excess fuel down the drain. (18)

A fourth question was the identity of the official charged with making the decision to evacuate an area. Was it the state governor or the city mayor? The governor said that the mayor should have that power. But in reality, as Varley points out, any local official’s ability to call for an evacuation was based on the degree to which he enjoyed the confidence of the governor, rather than his official position. (18)

The Hole in the Pipe that Leaked

The cause of the sewer explosion was traced to the installation of a water pipe by a contractor several years before the explosion, which leaked water on a gasoline line lying underneath, according to one expert. (19) The subsequent corrosion of the gasoline pipeline, in turn, caused massive leakage of gasoline into the sewers.

Summary

The Guadalajara sewer explosions were not caused by a terrorist act. Nevertheless, they demonstrate the potential damage that can afflict a city by ignited volatiles present in the honeycomb of sewer lines in most large cities.  

Sources:

1. GAO: “Securing Wastewater Facilities,” p. 1. March 2006. (GAO-06-390) Available at: www.gao.gov.                                                                                                                          

2. GAO: “Wastewater Security.” January 2005. (GAO-05-165)  Available at: www.gao.gov.                                                                                                                      

3. SEMP Biot #181: “What Are the Top Eight Vulnerabilities in Securing our Wastewater Treatment Plants Against Terrorist Acts?” March 3, 2005, at: http://www.semp.us/biots/biot_181.html; accessed May 3, 2006.

4. GAO: “Securing Wastewater Facilities,” p. 5. March 2006. (GAO-06-390) Available at: www.gao.gov.

5. “Commission for Environmental Cooperation, North American Free Trade Agreement” petition, p. 5. Available at:
http://www.cec.org/files/pdf/sem/98-1-SUB-Eo.pdf#search='commission%20for%20environmental%20
cooperation%20 north%20american%20free%20trade%20agreement%20guadalajara'; accessed May 3, 2006.

6. Peter Eisner: “Nine officials charged in sewer-line explosions case.” The Tech. April 28, 1992. Available online at http://www-tech.mit.edu/V112/N22/mexico.22w.html; accessed May 3, 2006.

7. Pamela Varley: “Responding to Disasters: The Story of the Guadalajara Sewer Explosion.” Kennedy School of Government Case Program (C16-94-1180.0). 1994, p. 4.

Available for a modest fee at: http://www.ksgcase.harvard.edu/; accessed May 3, 2006.

8. Ibid, p. 2.

9. “Pemex” at Wikipedia; http://en.wikipedia.org/wiki/Pemex; accessed May 3, 2006.

10. Pamela Varley: “Responding to Disasters: The Story of the Guadalajara Sewer Explosion.” Kennedy School of Government Case Program (C16-94-1180.0). 1994, p. 3.

Available for a modest fee at: http://www.ksgcase.harvard.edu/; accessed May 3, 2006.

11. See also: SEMP Biot #227: “What is a Rentier State?” June 24, 2005. Available at: http://www.semp.us/biots/biot_227.html; accessed May 3, 2006.

12. Pamela Varley: “Responding to Disasters: The Story of the Guadalajara Sewer Explosion.” Kennedy School of Government Case Program (C16-94-1180.0). 1994, p. 5.

Available for a modest fee at: http://www.ksgcase.harvard.edu/; accessed May 3, 2006.

13. Commission for Environmental Cooperation, North American Free Trade Agreement” petition, p. 4. Available at:
http://www.cec.org/files/pdf/sem/98-1-SUB-Eo.pdf#search='commission%20for%20environmental%20
cooperation%20 north%20american%20free%20trade%20agreement%20guadalajara'; accessed May 3, 2006.

14. Pamela Varley: “Responding to Disasters: The Story of the Guadalajara Sewer Explosion.” Kennedy School of Government Case Program (C16-94-1180.0). 1994, p. 6.

Available for a modest fee at: http://www.ksgcase.harvard.edu/; accessed May 3, 2006.

15. BE Aguirre, et al.: “”The Social Organization of Search and Rescue: Evidence from the Guadalajara Gasoline Explosion.” 1994. Disaster Research Center, University of Delaware. Available online at:  http://www.udel.edu/DRC/Aguirre/publications/ag57.pdf#search='The%20Social%20Organization%20of%20
Search%20 and%20Rescue%3A%20Evidence%20from%20the%20Guadalajara%20Gasoline%20Explosion'; accessed May 3, 2006.

16. James Dugal: “Guadalajara Gas Explosion Disaster” in Disaster Recovery Journal. Available online at: http://www.drj.com/drworld/content/w2_028.htm; accessed May 3, 2006.

17. Pamela Varley:  Responding to Disasters: The Story of the Guadalajara Sewer Explosion, Epilogue.” Kennedy School of Government Case Program (C16-94-1180.1). 1994, p. 11. Available for a modest fee at: http://www.ksgcase.harvard.edu/; accessed May 4, 2006.

18. Ibid, p. 18.

19. “Sewer explosion due to corrosion” at: http://www.corrosion-doctors.org/Localized/sewer.htm; accessed May 4, 2006.