At 4:30 pm, a vapour cloud deflagration and pool fire erupted at an industrial waste treatment facility, as 2 vacuum trucks were unloading basic sediment and water (BS&W) collected from 2 natural gas well sites. The first responders arrived on scene at 4:52 and reported an intense pool fire producing a large amount of thick black smoke and very intense heat, with flames 15 feet high. The fire was brought under control at 5:35 pm. Two employees were killed, and three were seriously burned, one of them died 2 months later. The fire destroyed two 50-barrel (2,100-gallon) vacuum cargo tank trucks owned and operated by a subcontractor, and heavily damaged equipment and structures in and around the operator’s unloading pad. The US CSB investigated the case and found out that the potential flammability of BS&W had not been properly studied (and therefore classified) by the waste producer. As a consequence, neither the waste producer nor the waste treatment facility did implement work practices to minimize the release of flammable vapour from BS&W and to safely handle releases. Their respective employees were not adequately trained on techniques to minimize the potential hazards of flammable liquids, on response to a system malfunction or site emergency, on general awareness of and familiarization with hazardous materials and on specific job functions.