At approximately 10:00 a.m. on May 25, 2018, three employees were working for a firm that disposed of waste and operated solid waste landfills. They were working at an oil and gas site. Three tanks were being decommissioned. They had been assisting in containing a spill during the decommissioning. The tanks were moved from the site to the bottom of a hill. There, a worker from a separate company cut open the tanks with an oxygen-acetylene torch so that they could be cleaned. The third tank contained a leak along the bottom seam. Once it was at the bottom of the hill, the three employees, along with a second worker from the separate company, were working to contain the sludge that was escaping. Nearby, the worker with the torch was on the opposite side of the tank. He began to heat the tank with the torch. The tank contained flammable material, either liquid or vapor escaping from the leaking seam, ignited. An explosion occurred inside the tank. All three employees sustained thermal burns. Two of the employees sustained relatively minor burns. They were flown to West Penn Hospital in Pennsylvania. They were hospitalized. One employee sustained severe burns. He was flown to UPMC Mercy Hospital in Pennsylvania. He died there on June 12, 2018.