Abstract: At 11:25 a.m. on April 16, 2019, an employee was working at a refinery operated by an international copper mining firm. The worksite was a surface bituminous or lignite coal mine. The employee was on a 2.4-meter (8-foot) portable Louisville ladder that he had found in a closet. The worksite had an acidic, corrosive atmosphere. Both of the rubber feet that were supposed to be on the ladder were missing. The ladder had not been taken out of service, marked as dangerous, or repaired. The employee was using the ladder to access a hydraulic valve panel on an overhead crane. Employees of the employer used multiple ladders in the course of their day. The only way to access the valve panel on the crane was through the use of ladders. The employee was on the third or fourth rung, 0.9 to 1.2 meters (three to four feet) above the floor at the time of the incident. Without its rubber pads, the ladder had nothing to keep it from slipping. The employee fell off the ladder. He suffered a fractured left leg when he landed on the ground. He was hospitalized. The worksite's atmosphere corroded metal. A nearly identical ladder nearby also showed signs of corrosion on the metal attachments holding the rubber pads on the feet. The employer also knew of problems associated with the crane that often require physical manipulation of various components.