Abstract: At 4:15 p.m. on April 29, 2022, a PG&E maintenance crew was conducting pipeline drying following hydrostatic testing of an approximately two-mile-long section of natural gas transmission pipeline. Two PG&E employees were operating the PIG launcher, and two other employees were operating the PIG receiver. The employees at the launcher loaded a foam swab PIG and a Polyethene follower PIG into the launcher, pressurized the system and attempted to send the PIG through the pipeline to the receiver. The PIGs did not arrive at the receiver within the expected time frame and other parameters indicated that the PIGs may have become stuck in the line. Employee #1 proceeded to the receiver location and directed the employees there to connect a portable air compressor to the line in an attempt to push the PIGs back to the launcher. He then returned to the launcher and after several vibrations and venting of the launcher vessel, Employee #1 determined that the PIG's had been pushed back to the launcher. He instructed Employee #2 to shut the vent valve on the launcher and he proceeded to prepare the closure door for opening. However, the closure door on the launcher vessel was opened and Employee #1 looked into the vessel with his flashlight in an attempt to verify the location of the PIG's. Employee #2 joined him and shined his own flashlight into the vessel as well. A loud noise was heard and the PIGs were dislodged, releasing the air pressure contained in the pipe, and the two PIGs were ejected at a high rate of speed. The launcher vessel isolation valve had not been closed and the pipeline between the receiver and launcher had not been depressurized prior to opening the closure door. The two employees operating the launcher were struck by the escaping air and/or the PIGs. Employee #1 died due to blunt force trauma to the head. Employee #2 sustained multiple facial lacerations and fractures, damage to the right eye, and a concussion and was hospitalized.