The PEPCON disaster was an industrial disaster that occurred in Henderson, Nevada on May 4, 1988 at the Pacific Engineering Production Company of Nevada (PEPCON) plant. The chemical fire and subsequent explosions claimed two lives, injured 372 people, and caused an estimated US$100 million of damage. A large portion of the Las Vegas metropolitan area 10 miles (16 km) away was affected, and several agencies activated disaster plans.[1]
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The PEPCON plant, located in Henderson, Nevada just outside of Las Vegas, was one of only two American producers of ammonium perchlorate, an oxidizer used in solid fuel rocket boosters, including the Space Shuttle and military weapons. The other producer, Kerr-McGee, was located less than 2.4 kilometers (1.5 mi) away from the PEPCON facility, within the area that suffered some blast damage. In addition to ammonium perchlorate, the facility also had a 16-inch (410 mm) high-pressure natural gas transmission line running underneath the plant.[2]
With the space shuttle program frozen as a result of the 1986 Challenger disaster, there was no government instruction dictating where to ship the product, and no mandated storage procedure or proper storage facilities existed for such large quantities of the product. PEPCON stored almost all manufactured ammonium perchlorate on-site. After all of the regular aluminum storage bins had been filled, HDPE plastic drums were used for additional storage and placed on campus parking lots. The HDPE plastic acted as a fuel and the ammonium perchlorate as an oxidizer.[3] An estimated 4000 tons of the finished product were stored at the facility at the time of the disaster.[4]
In addition to the PEPCON and Kerr-McGee facilities, there was also a large marshmallow factory, Kidd & Co.,[5] about 500 feet (150 m) away, and a gravel quarry in operation nearby. The closest residential buildings were about 1¾ miles (3 km) away.[2]
According to a report by the United States Fire Administration, the fire originated around a drying process structure at the plant between 11:30 and 11:40 a.m. that day. A windstorm had damaged a fiberglass structure and employees were using a welding torch to repair the steel frame, causing a fire that spread rapidly in the fiberglass material, accelerated by nearby ammonium perchlorate residue. The flames spread to 55-gallon plastic drums containing the product that were stored next to the building as employees tried in vain to put the fire out with hoses.
The first of a series of explosions occurred in the 55-gallon drums about 10–20 minutes after ignition, and employees had begun fleeing on foot or in cars. About 75 escaped successfully, but two were killed in subsequent larger explosions: Roy Westerfield, PEPCON's Controller who stayed behind to call the Clark County Fire Department; and Bruce Halker, who used a wheelchair and was thus unable to leave. Employees at Kidd & Co., the nearby marshmallow factory, heard the explosion and also evacuated.
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. Little fuel remained after that, causing the flame to diminish rapidly, except for a fireball that was supplied by the high-pressure natural gas line underneath the plant, which had been ruptured by one of the explosions. That gas line was shut off at about 1:00 p.m. by the gas company at a valve about a mile away.
There were a total of seven explosions during the accident. The two largest produced waves measuring 3.0 and 3.5 on the Richter scale. Nearly 4,500 tons (9 million lb) of the product exploded, creating a crater 15 feet (4.6 m) deep and 200 feet (61 m) long in the storage area.[2]
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.
Several nearby fire departments responded to the accident. Clark County units staged 1.5 miles (2.4 km) from the scene and assisted injured firefighters. The explosions and the raging fire were beyond their firefighting capabilities and they made no attempt to approach or fight the fire in recognition of the danger it posed.[2]
The Las Vegas Metropolitan Police Department, Nevada Highway Patrol and the 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. However, 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 (48 km) downwind.
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 one plant employee, but no trace of the other victim 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.[6] Fifteen firefighters were injured.
About four hours after the incident, hospitals were advised by the fire department that their disaster plans could be deactivated.[2]
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 (5 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.[2]
An investigation estimated that the larger explosion was equivalent to about 1,000 tons of TNT.[7]
Because PEPCON had only $1 million in insurance, a courtroom battle involving dozens of insurance companies and over 50 law firms resulted in a $71 million settlement that was divided among the victims and their families.[7]
After the incident, the company changed its name 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 no-build buffer around it. On July 30, 1997, an explosion at that plant killed one and injured four.[8]
Today the site is a commercial development near the Green Valley residential community. Kidd & Co rebuilt their plant on their original location.
The fire and explosions were caught on videotape by television engineer Dennis Todd, who was on Black Mountain performing maintenance on a television tower. The video footage can be seen frequently on disaster/survival-related television programs,[9] including the following:
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| Images | |
| The location of the disaster via Google Maps. | |
| Videos | |
| Forensic animations used in court. | |
| A video of the disaster on Google. | |
| A video of the disaster on YouTube. | |