HENDERSON, Nev. — May 4 marks the 25th anniversary of the most talked about industrial accident in Southern Nevada history, the 1988 PEPCON chemical explosion in Henderson that leveled the rocket fuel booster plant. 

A series of explosions shortly before noon at what was then the Pacific Engineering & Production Co. plant killed two individuals and injured more than 300 others.

The accident caused an estimated $100 million in property damage, including a ruptured natural gas pipeline and heavy losses to the Kidd & Co. marshmallow plant. Homes and schools also sustained damage.

Clark County Fire Department investigators say the explosions were set off by sparks from a welder’s torch. Sandia National Laboratories in New Mexico reported that the out-of-control fire began at 11:30 a.m. in the plant’s batch house. That was followed by a series of explosions, with the final and largest blast occurring at 11:57 a.m. Sandia estimated the blasts equated to a 1-kiloton nuclear explosion in free air.

“This could be reproduced by 250-tons TNT burst on the ground surface,” Sandia reported.

Of the 4,500 tons of the ammonium perchlorate chemical that was stored at the plant, an estimated 1,500 tons alone was detonated in the largest explosion. Sandia found evidence that the explosions caused shattered windows as far away as a furniture store on Sahara Avenue near Maryland Parkway, roughly nine miles away.

Pacific Engineering had been making perchlorate since 1958, with the chemical used as an oxidizer for the National Aeronautics and Space Administration’s space shuttle program and also as part of the Titan missile program. The accident dealt a severe blow to the nation’s perchlorate manufacturing capability, leaving only a neighboring Kerr-McGee Corp. plant in Henderson as the sole producer.

American Pacific Corp., the parent company of Pacific Engineering at the time of the accident, relocated its perchlorate manufacturing operation in 1989 to Cedar City, Utah. But the corporation in 2006 constructed a 9,000-square-foot remediation facility in Henderson near the original blast site to help clean up groundwater from decades of chemical seepage.

Remediation efforts at what is now the Black Mountain Industrial Complex were ordered by the Nevada Environmental Protection Division after perchlorate was found in Lake Mead, Southern Nevada’s primary source of drinking water. The chemical can lead to thyroid problems in adults and cause brain damage in infants.