Go Back > Internal Tunnel Rock Trap Debris Level and Loss
of Cross Section
Sonar of rock trap showing fill level.
Hibbard Inshore conducted an internal inspection of a large power tunnel to determine loss of head condition. First, we determined that the surge shaft contained large cracks. Second, we measured the level of debris in the rock trap by creating a cross section from sonar. Finally, we were able to show that a few large rocks had fallen to the invert from the wall of a rock-cut portion of the tunnel.
View of surge chamber from
ROV video camera.
ROV lowered into surge chamber for shaft inspection.
Video record of typical rock
in this rock trap.
Videocapture of three-foot-wide
rock (as measured on sonar)
in tunnel invert.
