Abstract: On October 13, 2010, Employee #1, newly hired, was conducting his first dive into a water tank and watching a coworker conduct the vacuuming operation of silt from the bottom. The depth of the water was 32 feet and after approximately 10 minutes, the coworker gave the vacuum nozzle to Employee #1. The coworker watched him conduct the work for about 5 minutes before leaving for the surface and departing the water tank. The coworker took his gear off and was holding the tie off rope when it went slack. He pulled all the rope in, and then reentered the tank and found Employee #1 on the bottom of the tank with his mask off. The coworker attempted to bring Employee #1 to the surface of the water, but was unable to inflate the dry suit or drag Employee #1 across and up to the surface on his own. The coworker resurfaced and climbed out of the tank. He yelled for another worker to call emergency services. Employee #1 was down for 20 minutes and both of his tanks of air were found empty. He was pronounced dead on the site.