Photo 2: A close-up showing the construction of the downstream caisson. Each caisson was drilled no less than 7’-0” into solid bedrock to provide a sound foundation. The drill arm, or kelly bar, of the drill rig is visible to the right in the photo. The casing pipe visible in the photo was a temporary casing that was used to aid in the installation of the permanent casing. It was removed once the permanent casing was set shortly after this photo was taken. Pete Schierloh photo.