What happened

An unintended chemical reaction in a tanker at Crystal Clean's environmental-services branch on Poplar Street triggered a hazardous-material response and neighborhood evacuation. Potassium hydroxide and sodium hydroxide had accidentally mixed with cooking oil, causing the approximately 1,900 gallons of material inside a 4,000-gallon tanker to heat up and release vapors. First responders found the tanker warm to the touch and still off-gassing, with an explosion considered the principal initial concern. Cayce police and firefighters evacuated 80 homes and nearby businesses within a quarter-mile radius, while Brookland-Cayce High School temporarily kept students and staff indoors. Twenty-five police officers and eight firefighters assisted with door-to-door warnings. The tanker gradually cooled, and a specialist contractor began removing the mixture by about 11:30 for safe transport. Authorities lifted the evacuation at approximately 13:00, allowing residents to return home the same day. No injuries were reported. Contemporary reporting initially described a suspected chemical leak, but subsequent official briefings characterized the event as chemical off-gassing from the reactive mixture rather than confirming a liquid release.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.