The project involved the draining/cleaning of one of the three cells of water tank storage for the city of Boston. The first component of the project was sampling to check turbidity, chlorine residual, and monochloramine. This water tank is a major artery in the water transmission for the city of Boston. As such, detailed reporting for 25 high level engineers on an hourly basis was paramount. We monitored the flow rate to reach an elevation such as to not disturb the sediment at the bottom. Once drawn down to the appropriate elevation, we monitored with hourly samples of water quality and pumped through a series of 5 frac tanks back to the influent side of this 1.65 billion gallon tank (5.5 acre by 30 ft deep tank). Once drained, we were able to begin all structural inspections and repairs of the 72” large diameter pipe and valve replacements.