View source for PEPCON disaster

{{Short description|1988 explosions and fire in Nevada}}
{{Use mdy dates|date=May 2018}}
{{Infobox event
|title = PEPCON disaster
|image = File:Pepcon mushroom.jpg
|image_size = 200px
|caption = The largest of the several explosions at the PEPCON plant
|date = {{start date and age|1988|5|4}}
|time =
|place = Pacific Engineering and Production Company of Nevada, [[Henderson, Nevada]], United States
|coordinates = {{coord|36|02|07|N|115|02|05|W|type:event_region:US-NV|display=inline,title}}
|also known as =
|cause = Unknown
|organisers =
|first reporter =
|filmed by = Dennis Todd
|participants =
|outcome =
|reported deaths = 2
|reported injuries = 372
|reported missing =
|reported property damage = US $100 million<br />(${{Format price|{{Inflation|US-GDP|100000000|1988}}}} in {{Inflation-year|US-GDP}} dollars){{inflation-fn|US-GDP}}
|burial =
|inquiries =
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|coroner =
|arrests =
|suspects =
|accused =
|convicted =
|charges =
|verdict =
|convictions =
|publication bans =
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|url =
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}}

On May 4, 1988, a fire followed by several explosions occurred at the Pacific Engineering and Production Company of Nevada (PEPCON) chemical plant in [[Henderson, Nevada]]. The disaster caused two fatalities, 372 injuries, and an estimated $100 million of damage. A large portion of the [[Las Vegas Valley]] within a {{convert|10|mi|adj=on}} radius of the plant was affected and several agencies activated disaster plans.<ref name="Reed">{{Cite report |last=Reed |first=Jack W. |title=Analysis of the Accidental Explosion at Pepcon, Henderson, Nevada, May 4, 1988 |url=http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA396009&Location=U2&doc=GetTRDoc.pdf |format=PDF-2.91 Mb |publisher=[[Sandia National Laboratories]] |date=November 1988 |access-date=August 13, 2015 |archive-date=October 8, 2012 |archive-url=https://web.archive.org/web/20121008111112/http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA396009&Location=U2&doc=GetTRDoc.pdf |url-status=dead }}</ref>

==Background==
The PEPCON plant, located in [[Henderson, Nevada]], {{convert|10|mi}} from [[Las Vegas]], was one of only two American producers of [[ammonium perchlorate]] ("AP"), an [[redox|oxidizer]] used in solid propellant rockets, including the [[Space Shuttle]] [[Space Shuttle Solid Rocket Booster|boosters]], [[Trident (missile)|Trident]] [[Submarine-launched ballistic missile|SLBMs]], and other rockets such as the [[MIM-104 Patriot|Patriot]].<ref name=Sutton>{{cite book|last1=Sutton|first1=George P. |last2=Biblarz|first2=Oscar |title=Rocket Propulsion Elements |date=2001 |publisher=John Wiley & Sons |location=New York |isbn=9780471326427 |pages=23, 474 |edition=7th |url=https://books.google.com/books?id=LQbDOxg3XZcC |access-date=August 13, 2015}}</ref> The other producer, [[Kerr-McGee]], was located less than {{convert|1.5|mi|abbr=on}} away from the PEPCON facility, within the area that suffered some blast damage. In addition to ammonium perchlorate, the plant produced other perchlorate chemicals including sodium perchlorate. The facility also had a {{convert|16|in|cm|adj=on}} high-pressure gas transmission line running underneath it, carrying [[natural gas]] at {{convert|300|psi|MPa|abbr=on}} [[Pressure measurement#Gauge|gauge pressure]].<ref name="Routley">{{cite journal|journal=USFA Technical Report Series |publisher=United States Fire Administration |access-date=January 7, 2009 |url=http://www.interfire.org/res_file/pdf/Tr-021.pdf |last=Routley |first=J. Gordon |title=Fire and Explosions at Rocket Fuel Plant – Henderson, Nevada }}</ref> The invoice for this pipe, which was installed in 1956, characterized it as "limited service".<ref>Invoice, Jackson-Marcus Supply Company (Los Angeles, CA, USA) issued to the Nevada Natural Gas Pipeline Company, February 10, 1956.</ref>

With the Space Shuttle fleet grounded as a result of the [[Space Shuttle Challenger disaster|''Challenger'' disaster]] two years prior, there was [[United States Government]] instruction that excess perchlorate&nbsp;– to be used for future Shuttle boosters and which was owned by the U.S. Government or its prime contractors&nbsp;– would be stored in customer-owned aluminum bins as customer-owned material at the PEPCON plant.<ref name="AMPAC">American Pacific Corporation, Las Vegas, NV USA, 89169, parent company of the former PEPCON subsidiary and current parent to the WECCO division which manufactures perchlorate chemicals, including Human Resources, employees on site 5-4-88.{{Original research inline|date=October 2014}}</ref> Ammonium perchlorate manufactured for other United States government programs was not held at the PEPCON plant during this period. [[High-density polyethylene]] (HDPE) plastic and steel drums were used for in-process and additional storage at the time of the accident, as they had been for many years prior to the ''[[Space Shuttle Challenger|Challenger]]'' accident.<ref name=AMPAC /> An estimated 4500 metric tons<ref name="Routley" /> of the finished product were stored at the facility at the time of the disaster.<ref name=AMPAC /><ref>{{cite web |url=http://blogs.techrepublic.com.com/geekend/?p=1294&page=2 |title=Fuel for Disaster |access-date=January 7, 2009 |last=Garmon |first=Jay |date=June 3, 2008 |work=TechRepublic.com |archive-url=https://archive.today/20120701183233/http://www.techrepublic.com/blog/geekend/geek-trivia-fuel-for-disaster/1294?pg=2 |archive-date=July 1, 2012 |url-status=dead }}</ref>

In addition to the PEPCON and Kerr-McGee facilities, there was also a large [[marshmallow]] factory, [[Kidd & Company]],<ref>{{cite web|url=http://www.reviewjournal.com/lvrj_home/1998/May-03-Sun-1998/news/7426880.html |title=The day Southern Nevada shook |access-date=March 16, 2009 |date=May 3, 1998 |work=Las Vegas Review-Journal Online |publisher=Donrey Newspapers |url-status=dead |archive-url=https://web.archive.org/web/20081229234751/http://www.reviewjournal.com/lvrj_home/1998/May-03-Sun-1998/news/7426880.html |archive-date=December 29, 2008 }}</ref> about {{convert|500|ft|m}} away, and a gravel quarry in operation nearby {{convert|3000|ft|m|sigfig=1}} to the west. The closest residential buildings were about {{convert|1+3/4|mi|km}} away.<ref name="Routley" />

==Fire and explosions==

{{OSM Location map
| coord = {{coord|36|00|00|N|115|00|00|W}}

| zoom = 8
| float = right
| width = 230
| height = 270
| mark-size = 12
| mark-coord =  {{coord|36|02|07|N|115|02|05|W}}
|caption = Location of the incident
}}Several theories have been advanced concerning the cause of the fire and explosions.<ref name="Luzik">Luzik, Steven J., Industrial Safety Division, U.S. Dept of Labor, Bruceton Safety Technology Center, Industrial Safety Division, ''Fire and Explosions Investigation Pacific Engineering and Production Company of Nevada May 4, 1988,'' 1988</ref> The [[Clark County Fire Department (Nevada)|Clark County Fire Department]] (CCFD) in [[Clark County, Nevada|Clark County]], Nevada, did not issue a formal report but did issue a two-page press release on July 15, 1988, 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 [[United States Department of Labor]] (USDOL), working with the Division of Occupational Safety and Health (DOSH), issued a lengthy report on the accident that discounted the cause and origin findings of the CCFD. USDOL noted that the Arson Division of CCFD maintained control over the site for several weeks and that DOSH and PEPCON investigating teams were not permitted entry into the facility until 13 days after the event.<ref name=Luzik /> The first significant DOSH inspection did not occur until 33 days after the fire.<ref name=Luzik /> At that time, the damaged areas had been disturbed and key evidence had been either displaced or removed from the site.<ref name=Luzik />

According to the USFA report,<ref name=Routley /> the fire originated around a drying process structure at the plant between 11:30&nbsp;a.m. and 11:40&nbsp;a.m. that day. USDOL reported that at least one fire was burning in a barrel located at the west side of the southern portion of the building partition, which separated the batch dryer from the batch tanks in the process building.<ref name=Luzik /> Fire was also reported on the north wall of the batch dryer section of the process building.<ref name=Luzik /> A windstorm had damaged a fiberglass structure and employees were using a welding torch to repair the steel frame. The USFA report stated that this activity caused a fire that spread rapidly in the fiberglass material, accelerated by nearby ammonium perchlorate residue.<ref name=Routley />

The USDOL report discounted this theory while relying upon eyewitness testimony and scientific burn tests.<ref name=Luzik /> Ten people testified that they saw the fire and/or participated in early fire-fighting activities.<ref name=Luzik /> USDOL reported that testimony indicated that welding operations had taken place somewhere between 30 and 90 minutes prior to the discovery of the fire.<ref name=Luzik /> These operations took place on the northwest wall of the building; the vicinity was thoroughly washed down prior to and during this task.<ref name=Luzik /> USDOL stated that the likelihood of transferring hot molten metal a distance of over {{convert|70|ft|m|sigfig=1}} through and around batch tanks to the batch dryer was considered extremely remote.<ref name=Luzik /> 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 {{convert|70|ft|m|sigfig=1}} 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".<ref name=Luzik />

Both the USFA and USDOL reports noted that the flames spread to {{convert|55|USgal|L|abbr=on}} plastic drums containing the product that were stored next to the building as employees tried in vain to put the fire out inside the building with water hoses.<ref name=Routley /><ref name=Luzik /> USFA<ref name=Routley /> reported that the first of a series of explosions occurred in the drums about 10 to 20 minutes after ignition, and employees had begun fleeing on foot or in cars. USDOL reported this differently, stating that the fire spread rapidly to the north side of the partition, northeast and south walls by radiative and convective heat transfer.<ref name=Luzik /> The extremely rapid fire spread in the process building and subsequent growth to other buildings was primarily due to the highly combustible fiberglass reinforced siding panels and close spacing of adjacent buildings.<ref name=Luzik /> High winds blowing in a northeasterly direction were a contributing factor.<ref name=Luzik /> Product stored in an area north of the process building heated up and approximately seven minutes later at 11:51&nbsp;a.m., an aluminum econobin containing approximately {{convert|4000|lb|kg}} of AP located about {{convert|30|ft|m|sigfig=1}} west of the northwest corner of the building detonated, causing damage to the surrounding structures and batch dryer.<ref name=Luzik />

The yield of this first detonation was estimated to be the equivalent of between 17 and 41&nbsp;kg (37 and 90 pounds) of [[TNT]].<ref name=AMPAC />

USDOL reported that considerable evidence suggested that natural gas leaks were present in the plant.<ref name=Luzik /> The on-site investigation of the plant revealed the presence of carbonaceous deposits around the perimeter of the foundation of the batch dryer building.<ref name=Luzik /> 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.<ref name=Luzik />

USFA reported that 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.<ref name=Routley /> USFA reported that 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. USDOL reported that six or seven detonations occurred solely in areas where aluminum econo bins or steel drums were utilized to store the product of nominal 200 micron size.<ref name=Luzik /> USFA reported that 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&nbsp;p.m. by the gas company at a valve about a mile away.<ref name=Routley />

USDOL also reported that there was strong evidence of a natural gas fire prior to the second explosion at the northeast edge of the plant within a {{convert|6|x|200|ft|m|0|abbr=on}} narrow band of soft sand.<ref name=Luzik /> The leading edge of this sandbar was located approximately {{convert|1100|ft|m|abbr=on}} from the batch dryer building.<ref name=Luzik />

USFA reported that there were a total of seven explosions during the accident.<ref name=Routley /> 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.<ref name=AMPAC /> The two largest explosions produced seismic waves measuring 3.0 and 3.5 on the [[Richter magnitude scale|Richter scale]].<ref name="USGS Data"/> 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 {{convert|15|ft|m}} deep and {{convert|200|ft|m}} long in the eastern storage area.<ref name="Routley" /> A large amount of AP remained on the ground after the incident and material was subsequently recovered and recycled within one year.<ref name=AMPAC /> The largest explosion had an estimated yield of 0.25 kiloton TNT equivalent (similar to a 1.0 kiloton nuclear explosion in free air).<ref name=Reed/>

USDOL concluded that the initiation mode of the fire was undetermined. It stated that smoking, sparking of electrical equipment, or frictionally ignited gas are among the probable igniting sources.<ref name=Luzik />

About 75 people escaped successfully, but two were killed in the last two larger explosions: Roy Westerfield, PEPCON's controller, who stayed behind to call the CCFD; and Bruce Halker, 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.

==Fire department response==

The fire chief of the City of Henderson, who was leaving the main [[fire station]] about {{convert|1.5|mi|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 {{convert|100|ft|m|abbr=on}} in diameter and dozens of people fleeing the scene.<ref name="Routley" />

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.<ref name="Routley" />

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.<ref name="Routley" />

Several nearby fire departments responded to the accident. Clark County units staged {{convert|1.5|mi|km}} from the scene and assisted injured firefighters. Recognizing the danger posed by a fire that was beyond their firefighting capabilities, they made no attempt to approach or fight the fire.<ref name="Routley" />

==Evacuation and overhaul of the scene==
{{More citations needed section|date=April 2023}}
The [[Henderson Police Department]], [[Nevada Highway Patrol]], [[Las Vegas Metropolitan Police Department]] and the [[Nevada National Guard]] evacuated a five-mile (8&nbsp;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; they were not considered highly toxic, nor was the danger of further explosions estimated as high. Authorities had considered expanding the evacuation zone to {{convert|10|mi|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 {{convert|30|mi|km|sigfig=1}} 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 Bruce Halker, the plant manager, but no trace of the other victim, controller Roy Westerfield, was ever found.<ref name=AMPAC />

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.<ref>{{cite web|url=http://www.reviewjournal.com/lvrj_home/1998/May-03-Sun-1998/news/7426849.html |title=Shattered windows, lives |date=May 3, 1998 |work=Las Vegas Review-Journal Online |access-date=March 16, 2009 |publisher=Donrey Newspapers |url-status=dead |archive-url=https://web.archive.org/web/20081229234344/http://www.reviewjournal.com/lvrj_home/1998/May-03-Sun-1998/news/7426849.html |archive-date=December 29, 2008 }}</ref> Fifteen firefighters were injured.

About four hours after the incident, hospitals were advised by the fire department that their disaster plans could be deactivated.<ref name="Routley" />

==Damage assessment and aftermath==
The explosions leveled the PEPCON plant and Kidd & Company marshmallow factory. Damage within a {{convert|1.5|mi|km|adj=on}} radius was severe, including destroyed cars, damage to buildings, and downed power lines. Damage to windows and moderate structure damage was recorded within {{convert|3|mi|km|spell=in}} of the incident.

The damage reached a radius of up to {{convert|10|mi|km}}, including shattered windows, doors blown off their hinges, cracked windows and injuries from flying glass and debris. At [[McCarran International Airport]], {{convert|7|mi|km|spell=in}} away in Las Vegas, windows were cracked and doors were pushed open. The shock wave buffeted a [[Boeing 737]] on final approach.<ref name="Routley" />

An investigation estimated that the larger explosion was equivalent to 0.25 kiloton of [[TNT equivalent|TNT]], approximately the same yield of a [[tactical nuclear weapon]].<ref name="Bellows">{{cite web |url=http://www.damninteresting.com/?p=800 |title=The PEPCON Disaster |access-date=January 7, 2009 |last=Bellows |first=Alan |date=September 10, 2008 |work=DamnInteresting.com |archive-url=https://web.archive.org/web/20090217113239/http://www.damninteresting.com//?p=800 |archive-date=February 17, 2009 }}</ref><ref name = "Reed"/>

In 1991, the Nevada legislature passed the Chemical Catastrophe Prevention Act, which led to Nevada's Chemical Accident Prevention Program.<ref name="CAPP">{{cite web |url=http://ndep.nv.gov/bapc/capp/capmore.html |title=Chemical Accident Prevention Program (CAPP) |access-date=February 9, 2013 |archive-date=February 13, 2011 |archive-url=https://web.archive.org/web/20110213083656/https://ndep.nv.gov/bapc/capp/capmore.html |url-status=dead }}</ref>

PEPCON had only $1&nbsp;million in stated liability insurance, but costs paid by its insurer significantly exceeded this amount.<ref name=AMPAC /> A courtroom battle involving dozens of insurance companies and over 50 law firms resulted in a $71&nbsp;million 1992 settlement  (equivalent to ${{Formatprice|{{Inflation|US-GDP|71000000|1992|r=-6}}}} in {{Inflation/year|US-GDP}}){{Inflation/fn|US-GDP}} 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.<ref name=AMPAC /><ref name="Bellows"/>

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).<ref name=AMPAC /> It built a new ammonium perchlorate plant in an isolated area about {{convert|14|mi|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.<ref name=AMPAC /> On July 30, 1997, an explosion at that plant killed one and injured four.<ref>{{cite news|url=http://lasvegassun.com/news/1997/jul/30/one-killed-three-injured-in-southern-utah-plant-ex/ |title=One killed, three injured in southern Utah plant explosion |work=Las Vegas Sun |date=July 30, 1997 |access-date=October 29, 2014}}</ref>

As of March 2023, the Henderson site is a commercial development near the Valley [[Auto Mall]] which is home to several dealerships and a university.<ref name=AMPAC />

==In popular culture==
Footage of the explosion has been shown in the following disaster and survival-related documentary-reality television shows:
*  The third episode of [[Discovery Channel]]'s ''[[Destroyed in Seconds]]'', aired in August 2008.<ref>{{YouTube|id=_KuGizBjDXo|title=Destroyed in Seconds - Chemical Plant Explosion}}</ref>
* An episode of ''[[Blueprint for Disaster]]'' features the explosion.
* An episode of ''[[Shockwave (TV series)|Shockwave]]'' features the explosion.
* The [[TLC (TV network)|TLC]] television special ''World's Most Powerful Explosions'' features the explosion.<ref>{{citation |title= World's Most Powerful Explosions |publisher= [[TLC (TV network)|TLC]] |date= July 31, 2002 |at= 51:50 }}</ref>
*  [[History (American TV channel)|The History Channel]] television special ''Engineering Disasters'' features the explosion.<ref>{{YouTube|id=FxUHXi3dYRE|title=PEPCON Disaster}}{{Dead link|date=April 2025}}</ref>
*  Season 6 Episode 4 "Memphis Bridge of Doom" of ''Engineering Catastrophes'' features an analysis of the explosion and its cause.<ref>{{Citation |title=Memphis Bridge of Doom |date=2022-12-07 |url=https://www.imdb.com/title/tt25385176/?ref_=ttep_ep4 |access-date=2023-05-20 |series=Engineering Catastrophes}}</ref>
* In the video game ''[[Fallout: New Vegas]]'', the fictional company REPCONN has its headquarters near the location of the disaster.

==See also==
{{Portal|United States}}
* [[List of industrial disasters]]

==References==
{{Reflist|refs=
<ref name="USGS Data">{{cite web |url=http://neic.usgs.gov/cgi-bin/epic/epic.cgi?SEARCHMETHOD=3&FILEFORMAT=1&SEARCHRANGE=HH&CLAT=36.0374&CLON=-115.035&CRAD=50&SYEAR=1988&SMONTH=05&SDAY=03&EYEAR=1988&EMONTH=05&EDAY=04&LMAG=&UMAG=&NDEP1=&NDEP2=&IO1=&IO2=&SLAT2=0.0&SLAT1=0.0&SLON2=0.0&SLON1=0.0&SUBMIT=Submit+Search |title=USGS NEIC: Earthquake Search Results |publisher=[[USGS]] |work=United States Geological Survey Earthquake Data Base |date=April 18, 2012 |access-date=April 18, 2012 }}
</ref>
}}

==External links==
*[https://web.archive.org/web/20080509073432/http://www.apfc.com/wec.php Western Electrochemical] – the company formerly known as PEPCON.
*[https://web.archive.org/web/20060419043456/http://www.reviewjournal.com/news/pepcon/ ''Las Vegas Review-Journal''] – a special section on the 10th anniversary of PEPCON, including videos.

[[Category:Explosions in 1988]]
[[Category:Explosions in the United States]]
[[Category:Disasters in Nevada]]
[[Category:1988 industrial disasters]]
[[Category:1988 in Nevada]]
[[Category:History of Henderson, Nevada]]
[[Category:Industrial fires and explosions in the United States]]
[[Category:May 1988 in the United States]]
[[Category:1988 disasters in the United States]]