MOBILE, Ala. — An 18-wheeler hauling sodium hydroxide overturned on U.S. Highway 90 near Telegraph Road and Interstate 165 on Tuesday morning, spilling the corrosive chemical along with leaking diesel fuel and shutting the highway down for hours while hazardous materials crews worked to contain it.
The Alabama Law Enforcement Agency said the crash happened around 11:20 a.m. No other vehicles were involved. First responders were dispatched shortly after 11 a.m., and state troopers reported no injuries.
Mobile Fire-Rescue Department crews, including the department’s Hazardous Materials team, responded to the scene at 55 Grover Ave., where travel was prohibited while the response was underway.
A Response That Changed Once Crews Arrived
The initial call did not describe what crews would actually be dealing with.
Mobile Fire-Rescue Capt. Steven Millhouse said crews were first dispatched to what appeared to be a diesel fuel spill — a common and comparatively routine call after a heavy truck goes over. Officials learned only after arriving that the tanker was also carrying sodium hydroxide.
That shift is the reason hazmat protocols exist. A diesel spill is an environmental containment problem handled with absorbent material. A load of concentrated sodium hydroxide is a chemical hazard requiring different equipment, different protective gear and a different containment strategy. Identifying the actual cargo early determines whether responders approach the scene correctly.
Mobile Fire-Rescue confirmed the truck was hauling 50% sodium hydroxide — a solution in which the chemical makes up half the mixture by weight.
What Sodium Hydroxide Is
Sodium hydroxide is commonly known as caustic soda or lye. It is one of the most widely used industrial chemicals in the country, appearing in soap making, drain cleaners, paper production and pH control processes across a range of manufacturing operations.
It is also highly corrosive. Direct contact with concentrated solutions damages skin and eye tissue, which is why the chemical is handled with protective equipment in industrial settings and why a roadway spill draws a full hazmat response rather than a standard cleanup crew.
What it does not readily do is become an airborne hazard. Sodium hydroxide is not volatile in the way that fuels and solvents are — it does not evaporate into a drifting vapor cloud at ambient temperature. That distinction shaped the public-safety message at the scene.
‘No Threat With Regards to Vapors’
Millhouse told reporters the public was not in danger.
“There is no threat with regards to vapors or water vapor, or anything like that. So this one’s just spilled on the ground, and as soon as the sand and dirt arrives, we’ll be able to cover it and ensure that it doesn’t spread any further,” Millhouse said.
That is a meaningful reassurance for a corridor like this one. The crash site sits in an industrial stretch of Mobile County near Prichard, with residential neighborhoods within a short distance. A chemical release that produced a vapor plume in that area would have triggered evacuations or shelter-in-place orders. A ground spill of a non-volatile corrosive is a containment job with a defined perimeter.
Sand, Dirt and Oil Dry
The cleanup used two different approaches for two different substances, which is why the response required materials trucked in from outside the fire department’s own inventory.
Crews covered the sodium hydroxide with sand and dirt supplied by Mobile Public Works and the Alabama Department of Transportation. Burying a corrosive liquid under absorbent earth stops it from migrating across pavement and into drainage, and allows the contaminated material to be scraped up and hauled off as a unit.
For the diesel, crews applied Oil Dry, a granular absorbent used routinely on fuel spills. Diesel behaves differently: it spreads thin across pavement, penetrates porous surfaces and creates both a slip hazard and a water-contamination risk if it reaches a storm drain.
Mobile Fire-Rescue reported the diesel contained early in the response, and by 1:05 p.m. said the spill overall had been contained.
Traffic Impact
The closure affected a significant piece of the local road network. U.S. 90 is a primary east-west route through the area, and the crash site near Telegraph Road and I-165 sits at a junction that carries substantial truck traffic serving the port and the industrial corridor north of Mobile.
Officials said U.S. 90 would remain closed until they were confident the cleanup was complete, and urged drivers to use alternate routes in the meantime. Travel on Grover Avenue was also prohibited during the response.
What Remains Unknown
Several questions had not been answered as of Tuesday afternoon. Authorities had not said what caused the truck to overturn, and had not released an estimate of how much sodium hydroxide or diesel escaped the tanker.
Cause determinations in commercial truck rollovers generally take time. Investigators typically examine vehicle speed, load distribution, the geometry of the curve or turn involved, road surface conditions and the driver’s hours of service before reaching a conclusion — and tanker rollovers carry an added complication, because liquid cargo shifting inside a partially filled tank can destabilize a truck in a way a solid load would not.
No injuries were reported in connection with the crash.