CASE STUDY ON PEPCON DISASTER IN NEVADA

CHM 3002 CHEMICAL SAFETY AND MANAGEMENT LECTURER : MOHD AL AMIN BIN MUHAMAD NOR

CASE STUDIES ON: PEPCON DISASTER, NEVADA By: SITI NURHANA BINTI ISMAIL (S62501) NURUL NADIRAH BINTI MOHAMAD SALIM (S61792) NUR ARYIENAH BINTI MAD SHIH (S61827) FATIN SHAHIDA AZWA BINTI ROSLI (S62261) NIK NUR HUSNA BINTI ISMAIL (S62335)

INTRODUCTION ___

On May 4, 1988 just before lunchtime, the Las Vegas Valley experienced one of the largest explosions in history – PEPCON. A fire started inside the building at Pacific Engineering and Production Company of Nevada (PEPCON) chemical plant in Henderson, Nevada. The disaster caused two fatalities, 372 injuries, and about $100 million of damage estimated. In four minutes, the fire rapidly spread and ignited three massive explosives.

An aeriel photo of the PEPCON site before the May 4, 1988, explosions.

An aeriel photo of the PEPCON site after the May 4, 1988, explosions.

BACKGROUND ___

PEPCON was one of the two American producers of ammonium perchlorate, a chemical found in solid fuel rocket boosters that is used for NASA Space Shuttles and military-grade weapons, according to the City of Henderson Historical Society. Existing ammonium perchlorate had to be carefully allocated and additional production capacity was needed.

The explosion caused an estimated $100 million in damages and impacted structures in a 10 mile (16 km) radius of the PEPCON plant, which is located on what is now the junction of US Highway 95 and the 215 Beltway. Two biggest blasts measured 3.0 and 3.5 on the Richter scale at observations in California and Colorado, NASA found. The explosions leveled the PEPCON plant as well as other nearby structures and buildings – windows were shattered, walls were cracked and doors were broken. The other producer, Kerr McGee Chemical Company, was located less than 1.5 miles (2.4 km) away from the PEPCON facility, within the area that suffered some blast damage. During the explosion, several piles of ammonium perchlorate exploded and a large gas main running under the plant also ruptured and exploded. PEPCON claimed the explosion was started by a leak from that gas main which caught fire and was then fueled by the ammonium perchlorate.In addition to the PEPCON and Kerr-McGee facilities, there was also a large marshmallow factory, Kidd & Company about 500 feet (150 m) away, and a gravel quarry in operation nearby (900 m) to the west. The closest residential buildings were about 2.8 km away.

The cause of the fire and explosions has been the subject of several theories. The Clark County Fire Department (CCFD) in Clark County, Nevada, did not issue a formal report, but on July 15, 1988, it did issue a two-page press release describing what it believed to be the cause of the fire; this and other CCFD information was incorporated into a report by the United States Fire Administration (USFA).

The U.S. Fire Administration is the lead federal agency for fire data collection, public fire education, fire research and fire service training.

The Clark County Fire Department provides fire protection and emergency medical services for the unincorporated areas of Clark County, Nevada, United States.

The US Department of Labor (USDOL) and the Division of Occupational Safety and Health (DOSH) produced a lengthy study on the accident, dismissing the CCFD's cause and origin findings.

According to USDOL, the Arson Division US Department of Labor reminds of the CCFD retained control of the site employers to avoid for several weeks and DOSH and compliance issues by ensuring PEPCON investigating teams were not worker safety, allowed entry into the facility until 13 proper pay practices this holiday season. days after the incident. The first major DOSH inspection didn't happen for another 33 days after the incident. The damaged regions had been disturbed at that time, and vital evidence had been misplaced or removed from the scene. Ammonium perchlorate The fire started around a drying process structure at the plant between 11:30 a.m. and 11:40 a.m., according to the USFA investigation.

According to the US Department of Labor, at least one fire was blazing in a barrel located at the west side of the southern portion of the building partition that separated the batch dryer from the batch tanks in the process building. A fire was also reported on the north wall of the process building's batch dryer section. A windstorm had wrecked a fiberglass structure, and workers were repairing the steel frame with a welding torch. According to the USFA study, this activity sparked a fire that spread quickly in the fiberglass material, accelerated by surrounding ammonium perchlorate residue.

The USDOL study dismissed this notion while relying upon eyewitness testimony and scientific burn test. Ten witnesses testified that they witnessed the fire and/or were involved in early firefighting activities. According to the US Department of Labor, testimony indicated that welding operations took place between 30 and 90 minutes before the fire was discovered. These activities took place on the building's northwest wall, and the area was properly wiped down before and throughout this task. Furthermore, according to the US Department of Labor, the chances of moving hot molten metal across a distance of more than 70 feet (20 m) through and around batch tanks to the batch dryer is considered extremely remote. USDOL stated that sparks from such operations would not present enough energy to ignite ordinary combustibles in close proximity, let alone at distances of up to 70 feet (20 m) and concluded that "the possibility of welding and cutting operations as a source of ignition is considered very low, in the author's professional opinion".

33 years ago on Tuesday, the PEPCON explosion happened in Henderson, killing two people and injuring hundreds more.

The flames spread to 55 US gal (210 L) plastic drums carrying the substance that were stored next to the building, according to both the USFA and USDOL reports, as employees tried in vain to put the fire out inside the building with water hoses. The first in a series of explosions in the drums occurred approximately 10 to 20 minutes after ignition, according to USFA, and employees began fleeing on foot or in cars. By radiative and convective heat transfer, the fire spread quickly to the north side of the partition, northeast and south walls, according to USDOL. The highly combustible fiberglass reinforced siding panels and close spacing of adjacent buildings contributed to the extremely quick fire spread in the process building and subsequent spread to other buildings. High winds coming from the northeast were a contributing cause. Product stored in an area north of the process building heated up and approximately seven minutes later at 11:51 a.m., an aluminium econobin carrying approximately 4,000 pounds (1,800 kg) of AP located about 30 feet (9 m) west of the northwest corner of the building detonated, inflicting damage to the surrounding structures and batch dryer. The yield of this first detonation was estimated to be the equivalent of between 17 and 41 kg (37 and 90 pounds) of TNT.

The considerable evidence suggested that natural gas leaks were present in the plant. The on-site investigation of the plant revealed the presence of carbonaceous deposits around the perimeter of the foundation of the batch dryer building. Other visual evidence of burning, possibly natural gas, from the ground was discovered in various portions of the plant including beneath the gas and telephone vaults and portions of the asphalt paving.

According to the USFA, the fire continued to spread in the stacks of drums creating a large fireball and leading to the first of four explosions in the drum storage area. The fire then made its way into the storage area for the filled aluminum shipping containers, resulting in two small explosions there and a massive explosion about four minutes after the first.

USFA reported that there were a total of seven explosions during the accident.

Eyewitness testimony and a video, which was filmed by Dennis Todd and began after the first detonation, as well as other resources indicated there were five high-order detonations: one north of the batch dryer, one in the storage area south of the administration building, two on the loading dock and the final largest detonation in the eastern storage area, where the gas line burned after the detonations occurred. The two largest explosions produced seismic waves measuring 3.0 and 3.5 on the Richter scale. Much of the approximately 4,500 metric tons of AP either burned/decomposed in combination with a fuel or exploded, with the final detonation creating a crater 15 feet (4.6 m) deep and 200 feet (61 m) long in the eastern storage area. A large amount of AP remained on the ground after the incident and material was subsequently recovered and recycled within one year. The largest explosion had an estimated yield of 0.25 kiloton TNT equivalent (similar to a 1.0 kiloton nuclear explosion in free air).

About 75 people escaped successfully, but two were killed in the last two larger explosions namely Roy Westerfield as PEPCON's controller, who stayed behind to call the CCFD and Bruce Halker as the plant manager, who stood near his car when the first major detonation occurred. Employees at the nearby Kidd marshmallow factory heard the explosion and also evacuated.

Evacuation & Overhaul Of The Scene

The Henderson Police Department, Nevada Highway Patrol, Las Vegas Metropolitan Police Department and the Nevada National Guard evacuated a five- mile ( 8 km) radius around the plant, concentrating on areas downwind of the explosion.

Roads in the area were clogged in both directions due to residents trying to leave and curious spectators headed toward the scene, creating a traffic jam that took over two hours to clear.

More than an hour after the first explosions, authorities concluded that the airborne products could be a respiratory irritant. It was not considered highly toxic, nor was the danger of further explosions estimated as high. Authorities had considered expanding the evacuation zone to 10 miles (16 km), but the idea was dropped due to the new information, although a few cases of respiratory irritation were reported in a small community about 30 miles (50 km) downwind.

Evacuation & Overhaul Of The Scene

Crews in protective clothing headed to the scene to clean up, a slow process due to leaking tanks of anhydrous ammonia and residue from acids and other products. Several firefighters had to undergo treatment for respiratory irritation. Overhaul continued until dusk and resumed the following day. Authorities found the remains of Bruce Halker, the Plant Manager, but no trace of the other victim, the Controller Roy Westerfield, was ever found

.

Emergency medical services treated and transported about 100 patients to five hospitals in the region, with the remaining 200 to 300 heading into hospitals on their own volition. Many of the injured had been struck by flying glass when windows were shattered. 15 firefighters were injured. About four hours after the incident, hospitals were advised by the fire department that their disaster plans could be deactivated.

Fire department response

The Fire Chief of the City of Henderson, who was leaving the main fire station about 1.5 miles (2.4 km) north of the PEPCON facility, spotted the huge smoke column and immediately ordered his units to the scene. As he approached the plant, he could see a massive white and orange fireball about 100 ft (30 m) in diameter and dozens of people fleeing the scene

At about 11:54, as he approached the site, the first of the two major explosions sent a shock wave that shattered the windows of his car and showered him and his passenger with glass. The driver of a heavily damaged vehicle coming away from the plant then advised the chief about the danger of subsequent larger explosions, which prompted the chief to turn around and head back toward his station. The other units also stopped heading toward the site after the explosion The second major explosion nearly destroyed the chief's car; after he and his passenger were cut by flying glass, he was able to drive the damaged vehicle to a hospital. The windshields of a responding Henderson Fire Department vehicle were blown in, injuring the driver and firefighters with shattered glass.

The second major explosion nearly destroyed the chief's car. After he and his passenger were cut by flying glass, he was able to drive the damaged vehicle to a hospital. The windshields of a responding Henderson Fire Department vehicle were blown in, injuring the driver and firefighters with shattered glass.

DAMAGE ASSESMENT AND AFTERMATH The explosions leveled the PEPCON plant and Kidd & Co marshmallow manufacturing facility. Damage within a 1.5-mile (2.4 km) radius was severe, including destroyed cars, damage to buildings and downed power lines. Damage to windows and moderate structure damage was recorded within three miles (4.8 km) of the incident.

The damage reached a radius of up to 10 miles (16 km), including shattered windows, doors blown off their hinges, cracked windows and injuries from flying glass and debris. At McCarran International Airport, seven miles (11 km) away in Las Vegas, windows were cracked and doors were pushed open. The shock wave buffeted a Boeing 737 on final approach. An investigation estimated that the larger explosion was equivalent to 0.25 kiloton of TNT, approximately the same yield of a tactical nuclear weapon. In 1991, the Nevada legislature passed the Chemical Catastrophe Prevention Act, which led to Nevada's Chemical Accident Prevention Program.

PEPCON had only $1 million in stated liability insurance, but costs paid by its insurer significantly exceeded this amount. A courtroom battle involving dozens of insurance companies and over 50 law firms resulted in a $71 million 1992 settlement (equivalent to $118 million in 2019) with contributions from multiple parties including AMPAC/PEPCON and Southwest Gas Corporation that was divided among insurance companies on subrogation claims as well as the victims and their families. After the incident, American Pacific Corporation changed the name of the perchlorate chemicals manufacturing subsidiary to PEPCON Production, Inc and within one year, to Western Electrochemical Co. (WECCO). It built a new ammonium perchlorate plant in an isolated area about 14 miles (23 km) outside of Cedar City, Utah with a substantial voluntary no-build buffer around it. Natural gas service to this WECCO facility is handled in a different manner (mostly above ground away from AP storage areas) than was the case at PEPCON. On July 30, 1997, an explosion at that plant killed one and injured four. Today, the Henderson site is a commercial development near the Valley Auto Mall which is home to several dealerships and a university. Kidd & Co rebuilt their plant on their original location. This facility is now owned and operated by the Clark County School District Facilities Service Center.

Survivor Overcompensation

This is not a phenomena officially found in human psychology literature, but as described below, it has been useful in understanding the reasons behind the PEPCON disaster. Significant research has been done regarding different disorders that follow the surviving of traumatic experiences. Amongst these are PTSD, OCD and others. However, it seems to be the case that after surviving a traumatic experience, the individual will readjust the threshold of preparedness that he or she originally had. In other words, if an individual has gone through a shortage of food, he or she is more likely to save more food than they would have saved previously. This phenomena, although still unnamed is particularly common amongst war survivors, who have a difficulty disposing things and justify keeping them by arguing that they might need it in the future. In relation to PEPCON disaster, the factory set their standards of production based on the needs of NASA, and after the Challenger disaster, they failed to readjust their production, and kept producing Ammonium Perchlorate based on what they might need as opposed to what they actually did.

CONCLUSION The May 4, 1988 PEPCON explosion still evokes astonished hindsight. With such vast explosive potential, how could the hazards of welding on such structure constructed in part with flammable msaterial not have been better assessed? It would be logical to minimize the relevance of this map of causes to an individual's work or project, especially if the individual's works does not involve hazardous material. But the dangers of potentially hazardous material (e.g., ammonium perchlorate, solid propellant, liquid propellant, hydrogen, hypergols) force us to realize things that have never happened before happen all the time.

Planning for failure, like designing for success, sometimes depends upon key assumptions to scope and scale the effort to the resources available. This scoping and scaling can lead to planning for the scenarios considered most likely, instead of worst credible. Coping with the worst credible outcome can easily exceed available resources; engineering should not only plan to prevent the outcome, but also how to recover lost critical functionality by accessing other resources.

Although the PEPCON disaster could have been even more catastrophic in terms of loss of life, the effect of disasters and emergencies has a resounding impact on the public in close proximity and also those far away.

REFERENCES Reed, J. W. & SANDIA NATIONAL LABS ALBUQUERQUE NM. (1988, November 1).

Analysis of the Accidential Explosion at PEPCON, Henderson, Nevada, May 4, 1988. DTIC . https://apps.dtic.mil/sti/citations/ADA396009 Vegas, F. L. (2021, May 4). 33 years ago: PEPCON explosion in Henderson.

YouTube. https://www.youtube.com/watch? v=y5BVRFqBg0A&feature=youtu.be Mniszewski, K. (1994). The Pepcon Plant Fire/Explosion: A Rare Opportunity in Fire/Explosion Investigation. Journal of Fire Protection Engineering, 6(2), 63–78. https://doi.org/10.1177/104239159400600201 Baker, S. (2018, February 9). Documentary: PEPCON Disaster. YouTube. https://www.youtube.com/watch?v=QihUAqsTWWU&feature=youtu.be Hawley, T. (2018, May 4). SPECIAL REPORT: PepCon disaster remembered 30 years later. KSNV. https://news3lv.com/news/local/special-reportpepcon-disaster-remembered-30-years-later

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