"Just before midnight on January 29, the crew working the graveyard shift in tunnel Number 3, which at 3,570feet was the shortest of the four tunnels, triggered a shot. When the muckers moved in to begin cleaning up, they saw light streaming over the heap of broken rock from the downstream direction and felt a strong draft blowing in their faces. Whoops and whistles resounded up and down the length of the dusty shaft and an impromptu celebration began: the first tunnel had been holed out."50 -Joseph E. Stevens "After the tunnels were all drilled out, we started in on the cement work, and that was quite a project. At first they had to go through and pour the invert, the bottom of the tunnel. Then after that was poured they built what they called a sidewall jumbo that they poured the sidewalls with. They built that on a track that was laid in the invert. That jumbo was moved ahead. After you poured one form, they collapsed that form, brought it in four or five inches, and then moved it on ahead to the next place, then set that at the proper spot and poured another one. That cement was brought in there on trucks and lifted up with a hoist. - Neil Holmes Early in 1932, the four diversion tunnels were "holed out." The fresh air blowing in from the far side encouraged the crews and hastened the process of excavating, cleaning, and laying concrete. Concrete-laying crews used a movable template to form 40-foot slabs for the invert (or bottom) lining within the diversion tunnels.