The White Rock Hydroelectric Tunnel is a 5-mile-long conduit that provides electricity by feeding pressurized water from Slab Creek Reservoir to the SMUD (Sacramento Municipal Utilities District) powerhouse. As the tunnel showed signs of aging, Drill Tech performed permanent critical infrastructure maintenance work necessary for repairs. This included retaining walls on remote roads, rope access mass scaling, and excavation of rock highwalls. All rock and steel debris along the tunnel had to be excavated and removed from the rock trap before the rock bolt and shotcrete work could begin.   

Construction was performed concurrently along the tunnel, and the site required compliance with environmental regulations including all CA SWPPP components. As water ran through the tunnel over shotcrete rebound, it was collected then pumped out of the adit to a treatment plant to be tested, treated, and discharged into a ravine feeding the American River. When the outage for repairs started, over 1,000gpm of water ran through the tunnel—dropping to 400gpm by the end of the outage. Drill Tech also developed and implemented all aspects of the tunnel’s safety plan such as communication and ventilation, including the primary ventilation system which was installed at the intake shaft at the dam site. The entire scope of the project was completed in one Winter outage (4.5 months) as opposed to the contractually two, meaning the job was finished one year early.