At 6:24 a.m., a car collided with a road tanker carrying 28 m³ of sulphuric acid on a section of Lyon’s ring road. The tanker landed on its side on the road’s embankment, struck a concrete block, and began leaking. The prefecture initiated the hazardous materials portion of the ORSEC emergency-response plan. The firefighters set up a cordon and closed the ring road to traffic. They searched for the source of the leak and found a thin, continuous stream of acid trickling out of a hole in the tank’s wall. As the leak was coming from under the tank, it was impossible to patch. The acid flowed into the ring road’s stormwater drains. The firefighters laid out drain covers and spread absorbent. The wastewater treatment plant located 2 km downstream and the drinking water pumping stations were alerted. A slick measuring 12 m long and 0.8 m wide formed in the network and began flowing toward the WWTP.

A chemical manufacturer near the scene of the accident provided emergency services with technical and material support via the French chemical industry’s Transaid network. They injected water and sodium bicarbonate into the stormwater network. Neutralisers were also used at the WWTP to limit the sulphuric acid’s effects. At 12:00 p.m., a contractor recovered a total of 10 m³ of acid from the tank. The tanker was righted at around 2:00 p.m. and then taken away. A stormwater detention pond was neutralised with calcium hydroxide. The acid in the embankment was pumped out and the waste was collected. The road was reopened to traffic at around 5:30 p.m. and the ORSEC plan was lifted.

According to the carrier, two cars collided ahead of the tanker. To avoid crashing into them, the tanker’s driver swerved and hit the guardrail.