Abstract: At approximately 2:30 p.m. on July 23, 1988, Employees #1 and #2 went to the site of a dam for a small lake where they were to turn off a valve controlling an 8 inch silt pipe that went through and under the dam. The valve was located at the bottom of a concrete lined shaft that was 33 feet 6 inches deep by 4 feet in diameter and closed at the top by a concrete top with a 24 inch manhole and cast iron cover. The employees entered the shaft. They were discovered dead at the bottom of the shaft the next day at 10:00 a.m. The apparent cause of death was asphyxiation due to oxygen deficiency and/or toxic gases in the shaft atmosphere. No ventilation was performed, and protective breathing apparatus was not used.