Thyssen Mining, Inc. AAI conducted a review of the tunnel design (completed by others) and recommended changes for Thyssen Mining (the construction contractor) whose corporate office is located in Regina, Saskatchewan, Canada. The review effort was related to the design and construction of an underground water diversion tunnel located near the city of Leadville, Colorado, USA. The facility included multiple inlets and branch tunnels with a single downstream outlet. The review and recommendations included tunnel geometry, the rock mass classifications, and ground support requirements. Once tunnel construction was initiated, AAI made site visits to confirm that the appropriate ground support was being properly installed. AAI’s project work took place in 2012 and 2013.