Abstract: On October 17, 2003, Employee #1 and a coworker were at a water plant hot-tap installing a Risonic sensor transducer in a thick water pipe that measured 108 inches wide and was located in a concrete vault. The transducer measured approximately 7 inches long and weighed 4.5 lbs. During the installation Employee #1 and the coworker were working from a single-level scaffold. As Employee #1 was using an isolating drilling machine to make final adjustments, the machine disengaged from the pipe and struck him in the head. Employee #1 was pushed backwards and fell off the scaffold, striking the vault wall that was approximately 70 inches behind him. He then fell to the bottom of the vault, which was rapidly filling with water. Emergency services were contacted and search and rescue procedures begun; however, Employee #1 was consumed by the water and drowned. Emergency services retrieved Employee #1 from the water and determined that he was beyond resuscitation, pronouncing him dead. Under further examination by a medical professional, it was determined that Employee #1 had extensive skull and facial fractures, along with lacerations and brain hemorrhaging.