On 4 May 1988, an accidental fire and several explosions destroyed the Pacific Engineering Company (PEPCON) plant in Henderson, Nevada. The largest explosion, estimated as 500,000 pounds TNT equivalent weight, caused significant damage to the surrounding community, including portions of the Las Vegas metropolitan area. In 1990, property insurers joined in a lawsuit to recover their damage claim payments. With over 17,000 claims, the total alleged payment from the insurers totaled about $77 million. Through the legal discovery process, the defense team obtained copies of all damage claims; pertinent information was subsequently entered into a database. In 1992, Lloyd's of London, the basic defense underwriter, agreed to a $70 million settlement. Using the damage claim database, the authors were provided with a rare opportunity to evaluate actual damage costs resulting from an explosive detonation. The results are striking. According to DoD 6055.9-STD, the expected repair cost for an unstrengthened building, located at the Inhabited Building Distance (IBD) from an accidental detonation, is approximately 5 percent of the building's replacement cost. In the PEPCON accident, the nearest residences to the plant were located at distances much greater than the IBD. However, despite these greater distances, paid damage claims for these residences approached 20% of their replacement values. If the residences had been located at the IBD, they would have suffered significantly more damage, resulting in even higher claim costs. Clearly, DoD 6055.9-STD vastly underpredicts damage costs for these exposures. In this paper, we will first review current DoD safety regulations. Next, we will discuss the PEPCON accident and the calculation of blast overpressures resulting from the accident. We will then present the actual damage claims and will analyze their variation with overpressure.

Provides information on FEMA regulations and policy on substantial improvement as it applies to damaged structures.

Following the two damaging California earthquakes in1989 (Loma Prieta) and 1994 (Northridge), many concrete wall and masonry wall buildings were repaired using federal disaster assistance funding. The repairs were based on inconsistent criteria, giving rise to controversy regarding criteria for the repair of cracked concrete and masonry wall buildings. To help resolve this controversy, the Federal Emergency Management Agency (FEMA) initiated a project on evaluation and repair of earthquake-damaged concrete and masonry wall buildings in 1996. The ATC-43 project addresses the investigation and evaluation of earthquake damage and discusses policy issues related to the repair and upgrade of earthquake-damaged buildings. The project deals with buildings whose primary lateral-force-resisting systems consist of concrete or masonry bearing walls with flexible or rigid diaphragms, or whose vertical-load-bearing systems consist of concrete or steel frames with concrete or masonry infill panels. The intended audience is design engineers, building owners, building regulatory officials, and government agencies. The project results are reported in three documents. TheFEMA306report, Evaluation of Earthquake Damaged Concrete and Masonry Wall Buildings, Basic Procedures Manual, provides guidance on evaluating damage and analyzing future performance. Included in the document are component damage classification guides, and test and inspection guides. FEMA 307, Evaluation of Earthquake Damaged Concrete and Masonry Wall Buildings, Technical Resources, contains supplemental information including results from a theoretical analysis of the effects of prior damage on single-degree-of-freedom mathematical models, additional background information on the component guides, and an example of the application of the basic procedures. FEMA 308, The Repair of Earthquake Damaged Concrete and Masonry Wall Buildings ,discusses the policy issues pertaining to the repair of earthquake-damaged buildings and illustrates how the procedures developed for the project can be used to provide a technically sound basis for policy decisions. It also provides guidance for the repair of damaged components.

On May 4, 1988, the PEPCON plant experienced three major and several smaller explosions that caused over $70 million in property damage and caused two deaths. The PEPCON plant produced Ammonium Perchlorate (AP), a major ingredient for rocket fuel. The PEPCON plant and the nearby Kidd Marshmallow plant were totally destroyed by the detonations. The initiating event for the explosions was a fire that originated in the Batch Dryer Building and spread to adjacent storage. Several factors combined to cause the AP in the major storage fields to detonate, the most important being lack of adequate separation between storage units. Welding and flame cutting procedure with poor fire watch protocol was the prime candidate for fire ignition. There were no automatic fire suppression systems at the plant. Buildings including the Batch Dryer Building were made of combustible building material (fiberglass). There was poor housekeeping and no control of AP dust generation. AP was stored in combustible polyethylene drums, aluminum tote bins, 30-gallon steel storage drums and fiber reinforced tote bags. There were high-density storage practices. In addition, a contributing factor to the rapid fire-spread was that the wind that day was blowing directly from the batch dryer building to the storage areas. This paper claims that if codes, standards, and well-known hazard identification safety techniques were implemented at PEPCON, then the disaster would have been averted. A limited scope probabilistic risk assessment was conducted to establish the effectiveness of various preventive and mitigative features that could have been deployed to avert the disaster. The major hazard at the PEPCON site was fire and explosion involving the processing, production and storage of AP, which was then and is currently stored as a class 4 oxidizer. Since minute quantities of contamination can cause AP to be detonable by shock, there has been an ongoing debate concerning its reclassification to a class-A explosive.