Pacific Engineering and Production Company of Nevada (PEPCON) was built near Henderson Nevada in 1958. PEPCON was a chemical plant that specialized in the production of ammonium perchlorate, a chemical compound that was, and continues to be, primarily used as the oxidizer component of solid propellant for rockets and missiles. In 1982, PEPCON was acquired by American Pacific Corporation (AMPAC), and on May 4, 1988, PEPCON was destroyed by a large fire and several subsequent explosions that involved on-site storage containers filled with ammonium perchlorate, among other factors.
The Nevada Division of Environmental Protection (NDEP) investigated the destroyed PEPCON site from 1988 to 1995 for the presence of contaminants in the soil and groundwater. Remediation programs were implemented by AMPAC to remove contaminants of concern. From 1997 to 2004, several groundwater monitoring wells were installed in areas adjacent to, and at longer distances from, the former PEPCON site in order to determine the presence of any perchlorate in the groundwater. Perchlorate was discovered in the groundwater beyond the boundaries of the former PEPCON plant site. Subsequent to a pilot test conducted in 2002-2003, in June 2006, AMPAC began operation of an in-situ bioremediation system designed to treat the perchlorate-impacted groundwater at the northern end of the discovered perchlorate plume and prevent perchlorate migration into the Las Vegas Wash.
In 2012, AMPAC abandoned the in-situ bioremediation system and began operation of a new and larger ex-situ bioremediation system comprised of fluidized bed reactors and additional extraction wells located closer to the former PEPCON plant. This change in approach, subsequent to an extensive groundwater modeling effort that began in 2008, was designed to speed up the remediation process timeline significantly. Daily perchlorate mass reduction rates have been more than 40 times the rates observed using the in-situ system from 2006-2012.
In 2015, Endeavour, LLC was formed to continue operation of the treatment facility and the ongoing perchlorate remediation effort. Endeavour LLC now has remediation responsibilities previously undertaken by AMPAC in the June 2013 Administrative Order on Consent with NDEP.
During the first half of 2021, Endeavour's fluidized bed reactor-based groundwater treatment system treated approximately 186 million gallons of perchlorate-impacted groundwater, from which more than 133,000 pounds of perchlorate were successfully removed. Since its inception in 2012, the fluidized bed reactor system has removed more than three million pounds of perchlorate from the groundwater. Periodic maintenance and performance optimization of the groundwater treatment system helps prevent migration of perchlorate into the Las Vegas Wash and ensure that progress is continuously being made toward successful cleanup of the perchlorate plume.
Perchlorate, a chemical that dissolves easily in water, was discovered in the Lower Colorado River in 1997. It was ultimately determined that the source of the perchlorate was contaminated groundwater underlying the former PEPCON and Kerr-McGee sites, which had been involved in the perchlorate production business for several decades. Treatment systems were subsequently implemented by both sites to remove the perchlorate from the impacted groundwater. The treatment systems are currently operated by Endeavour and the Nevada Environmental Response Trust.
Download the EPA's Technical Fact Sheet to learn more about perchlorate.
View the perchlorate plume map to see where the perchlorate is located.
*Laboratory reports, figures, and/or appendices have been omitted from these documents. For a copy of the full report, please contact Alan Pineda.
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For more information, please contact Alan Pineda at alan.pineda [at] ndep.nv.gov or 702-668-3925.
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