This project involved the placement of a partially reinforced concrete floor to facilitate foot traffic and light equipment within the tunnel, as well as the removal of approximately 20-30 cubic yards of log debris that had collected at the upstream end of the tunnel. The horseshoe-shaped tunnel cross-section was eight feet wide by eleven feet high with a 1% slope, approximately 400 feet in length. The Tunnel was concrete lined from the entrance, extending 100 feet upstream. The remaining 300 feet of tunnel was unlined and unimproved, and typically submerged under 12-24 inches of relatively static water that would leak from a valve chamber near the tunnel plug at the upstream end of the Tunnel. This project scope was completed under the Tunnel Safety Orders as referenced in Cal/OSHA Title 8 Regulations.
