Abstract: At approximately 7:00 a.m. on November 21, 1994, Employee #1 and a coworker, laborers, began removing the rubber bladder plugs from a 48 inch storm sewer drain system to allow the construction site to drain off standing water captured by the blocked line. They climbed into the 10 foot deep manhole D-2, and placed two jointed pieces of 2 by 4s against the end of the metal portion on the rubber bladder plug and the manhole wall to prevent the plug from being swept downstream in the 48 inch storm sewer drain pipe. They then climbed out of manhole D-2. Air pressure was released from the plug installed in the storm sewer drain pipe in manhole D-2 to allow the stored water to pass. Employee #1 told his coworker to release the air pressure from the plug in manhole mixing box D-3, located approximately 71 feet away and upstream adjacent to the flightline. When the coworker arrived at mixing box D-3, it was under water. The employees conversed and the coworker was told to take the air release valve assembly out of the air vent hose to completely deflate the upstream plug. The employees knew this plug was secured by a rope attached to mixing box D-3. They stood around the opening to manhole D-2, and conversed when they noticed the 2 by 4 brace holding the rubber bladder plug in manhole D-2 in the inflow pipe was coming loose. Employee #1 entered manhole D-2 without an access ladder and attempted to shore up the brace by stomping it back into a horizontal position while standing on the lip of the outbound pipe. He was washed down the storm drain and drowned.