A 200-litre leak of hydrochloric acid, used at a water softening unit, occurred on an 800-litre tank within a glassworks operation. The accident was caused by the failure of retaining studs on the lower closing plate of a level gauge. The acid flowed into a retention basin that had not been fitted with a lining resistant to corrosive products and whose sidewalls were cracked (differential settlements). The acid poured out into a discharge manhole, crossed a metering channel and emptied into the LOING River Canal. Firefighters set up a sand dam. Local fauna suffered. The plant operator revised all onsite retention facilities and installed leak detectors. A containment basin was approved for construction within the month following the accident.