Fire and Explosion at Oil Field Saltwater Disposal Plant, Sidney, Montana
An explosion and subsequent large fire occurred at a saltwater disposal (SWD) plant near Sidney, Montana, in the oil fields of eastern Montana on Wednesday, June 25, 2025, around 8:00 p.m. The blast was reportedly felt by residents up to 10 miles away. The facility was unoccupied at the time, and no injuries or fatalities were reported.
Incident Summary and Facility Description
The incident took place at a saltwater disposal site located about 3 miles south of Sidney. Facilities of this type are an essential part of oil and gas production, particularly in regions like the Bakken Shale. They are designed to manage and dispose of "produced water" or "oilfield brine," which is a byproduct of oil and gas extraction. This produced water is highly saline and often contains dissolved gases, small amounts of residual hydrocarbons (oil and volatile organic compounds or VOCs), and other solids. The process typically involves separating any remaining oil from the water, which is then injected deep underground into suitable geological formations for disposal via injection wells. The facility in question contained multiple storage tanks and, reportedly, propane tanks, and experienced a fire before the explosion. The explosion initiated a chain reaction that resulted in a large fireball and continued burning of several storage tanks. Fire crews were unable to directly fight the fire due to the danger of further explosions and instead contained the area, allowing the fire to consume its fuel supply naturally.
Speculation on Potential Causes
The cause of the initial fire and subsequent explosions remains under investigation.
Initial Fire and Ignition Source: The fire preceded the explosion. Produced water can still contain dissolved or entrained hydrocarbons (oil and natural gas/VOCs) which can separate and accumulate in the vapor space of storage tanks. A flammable vapor cloud could have formed, and an ignition source would be required to start the fire. Potential ignition sources could include static electricity during transfer operations (especially if tanks were venting flammable vapors), a lightning strike (depending on weather at the time), or equipment malfunction such as a pump seal failure or an electrical fault.
The Explosion: Once the fire started, the heat transfer to nearby storage vessels, including the reported propane tanks and any tanks containing hydrocarbons, would increase the internal pressure. If tank venting systems were inadequate, or if the tanks were not designed for the sustained pressure increase from an external fire, the pressure inside could have exceeded the vessel's failure limit, leading to a catastrophic rupture known as a Boiling Liquid Expanding Vapor Explosion (BLEVE) or simply a rapid overpressure failure. Reports indicate a "chain reaction of explosions," suggesting multiple tanks were involved.
Application of API Standards
API Recommended Practice (RP) 752, Management of Hazards Associated with Location of Process Plant Portable Buildings, and API RP 753, Management of Hazards Associated with Process Plant Buildings
Although these Recommended Practices are primarily aimed at buildings meant for personnel, the underlying principles relate to facility siting and reducing personnel exposure to blast, heat, and toxic hazards.
Facility Siting and Blast Protection: Had there been a regularly occupied structure on site, the facility siting guidelines in API RP 752/753 would have necessitated an analysis of the blast, fire, and toxic release hazards from major equipment (like the storage and propane tanks). This analysis would determine a safe separation distance or require blast-resistant construction to mitigate the effects of an explosion, like the one that sent a shockwave 10 miles away.
Controlling Inventory and Layout: The standards indirectly promote better safety management by requiring a clear understanding of potential incident scenarios. Adherence to standards like API Standard 650/653 (for design and inspection of aboveground storage tanks) and API RP 500/505 (for electrical area classification and equipment selection) could help prevent a release or ignition in the first place. The devastating consequences seen in this incident—the chain reaction of tanks burning and exploding—emphasizes the need for proper separation (siting) of hazardous inventory, which is a key concept in facility layout design supported by this suite of RPs. Proper spacing between tanks, as guided by other fire protection codes, helps to prevent a domino effect when one tank fails due to fire.
Top Three Sources of Information
"Fire, Explosion at MT Oil Storage Site" - ISSSource (Source 1.1)
"Oil field disposal plant in eastern Montana explodes, no injuries" - AP News (Source 1.8)
"Industrial Plant Explodes With Explosion Felt Miles Away" - Suggest (Source 3.2)