"Doggone, pretty tricky job. Twenty ton bucket [of concrete] roaring down the canyon just as fast as they could get it there. And the fellow that was running the crane couldn't even see where that bucket was going. He was steering that thing by braille, boy, I'll tell ya. "66 - Blaine Hamann "I was assigned the job of operating and maintaining the cooling system which cooled the mass concrete in the dam. As you well know, when the concrete sets up, there's a chemical reaction that generates a tremendous amount of heat... My job was not to install the cooling pipe in the concrete itself but to connect and operate the cooling system that provided the cooling. Every five feet, vertically and horizontally, there was a one-inch-diameter cooling pipe embedded in the concrete... You can imagine the many, many miles of tubing it would take to run a one-inch-diameter tubing from the center each way to the canyon wall and back. What it amounted to was a huge radiator."67 - Bruce Eaton As the uneven checkerboard of the dam assumed a crescent shape, crowds gathered to stare down into the abyss. By pouring the mixture into boxes, Six Companies offset the considerable heat concrete produces as it hardens. Note the dot-like buckets of concrete being lowered to each side of the forms. Had the dam been poured in an enormous wedge, it would have cooled over 125 years and fractured. Instead Six Companies engineers threaded the honeycomb of concrete blocks with one-inch pipes, then pumped river water through the pipes to control cooling. This closeup taken February 20, 1934, shows the cooling pipe layout in panel H-3.