On October 19, 2019, @ 07:15 a.m., a contractor employee was standing on a scissor lift and replacing insulation on the pipes in the engine room of Building 3. As the employee lowered the scissor lift, the walking platform of the scissor lift where a technician was standing struck the service drain valve (3ML 3064) and cracked the nipple at the thread, causing an uncontrolled release of pressurized anhydrous ammonia.