Project Description

In 1996, LACHEL & Associates, Inc. (LFA) was selected to inspect the Long Lake Phase of the Snettisham Hydroelectric Project which was constructed by the Alaska District of the U.S. Army Corps of Engineers between 1968 and 1973 and included an approximately 8,400-ft-long, 13.5-ft-diameter power tunnel, an 8.5-ft-diameter, 900-ft-long steel penstock and an underground powerhouse housing two Francis type turbines with an installed capacity of 47 MW. Power was first transmitted to Juneau in 1973.

Scope of Services

LFA performed both the penstock and tunnel inspection of the tunnel which is now over 25 years old and has been operating without any inspection for approximately the last 13 years. The inspection team began at the access adit, traversed the 8,500 feet to the slide gate and returned back out the access adit, concluding that there was an apparent lack of problems associated with the Long Lake Power Tunnel, a testament to the excellent quality of the Snettisham Project bedrock and the skill of the miners and construction workers who built the tunnel. For Mr. Dennis Lachel who conducted the survey, this inspection was a trip back in time. In the summer of 1964, Mr. Lachel was a young Engineering Geologist working for the Alaska District of the Corps assigned to the first exploration team on the project. Over the next eight years he became the principal designer of the diversion and power tunnels, and then came out to the site as the project engineer on the diversion tunnel, at that time thought to be the first underwater lake tap in North America. For him, inspecting the Long Lake power tunnel was like visiting an old friend.

Client

Alaska Industrial Development and Economic Authority