Between the years 1935 and 1940, a six and a half mile tunnel was built to connect the Loch Raven Reservoir with the Montebello Filtration Plant. This is the story of the men who built this tunnel as told through the engineers and inspectors personal journals. They not only wrote on the tunnel progress, but also on the daily issues of life at the site. Union troubles and a tunnel explosion occupied their writings for one whole year. How ten men were killed in the tunnel explosion was never revealed.