Great story. Reminds me of the first cleanup the summer shutdown after production began at Diamond Star Motors. The Japanese wanted to clean the bottom of the settling tank for the whole plants paint system. The tank was supposed to be self cleaning with a skimmer system. It was something like 100,000 gallons and about 20 feet deep. They gave the guys boots so they wouldn't get their shoes dirty at the bottom of the tank. So they drained the tank only to find that there was about 4 feet of water on top of 16 feet of paint sludge. Time for plan "B".