The race director announced this in an official email. Athletes will enter the corral by waves, and then be grouped into pairs. Each pair leaves 5 seconds after the previous pair.
Brian Satola, the RD, also points out that Half Full is really not intended for first-time triathletes because of the length of the race and the hilly terrain.
At least the temperatures should be more moderate than the hot conditions we saw at yesterday's Washington DC Tri.