Spirit Lake Tunnel Repair
Otak provided surveying services for the Mount St. Helens Spirit Lake Outlet Tunnel Project. Serving as a subconsultant to Catworks, our surveyors established control points within the tunnel and laid out new support ribs. The project reached 6,000 feet into the tunnel and resulted in finalized as-built drawings for the 60-foot repair area. We established survey control inside the tunnel and marked the locations for work to take place using robotic total station survey equipment. We reproduced the tunnel alignment to include a control map listing the record, as-measured control points, and alignment of the tunnel stationing. The remote location, conditions, and schedule made for a unique and difficult project: the tunnel, located over two hours from accommodations, was a mile and a half long and 11 feet in diameter, dark and strongly ventilated, with running water between two and 40 inches deep. Our crew worked 14 hours a day for five days, starting on a Friday. Because the work depended on weather and coordination with five agencies, the Otak team had to be ready to respond at any time and on any day of the week.
Client: U.S. Army Corps of Engineers
Date Completed: June 2016
Project Manager: Dale Barrett
Otak Team Contract Amount/Total Project Cost: $35,000
Type: Surveying & mapping