Description of Event:
A contractor was performing bathymetry in the boat restricted zone (BRZ) of the plant forebay. The work boat was not equipped with a kicker motor, so a second boat was used as a safety/tow boat. The safety boat’s motor ran aground, and the boat required a tow from the work boat. The work boat was unable to overcome the flow of the partially open spillway and generating units while towing the safety boat from the rear. The flow from the spillway and units pulled the boats towards the dam.
The plant operators closed five spillgates and reduced plant output by approximately 100MW. Plant crews were dispatched to aid the two contractor boats. The contractor was able to get the safety boat re-connected and towed away from the dam before the boats drifted into the dam face. The two contractor boats tied up to the work barge and a stop work was executed.
Actions Taken:
Contractor’s boats were secured and spill and plant operations resumed.
Method & Findings:
The contractor’s boats were operating in the BRZ.
Critical Factors:
System Gaps:
Failed Barriers:
Causal Factors:
Critical Controls:
Supporting Materials:
Corrective Actions:
Boat operators will always have an observer on the boat in the BRZ.
All watercraft in the BRZ to have a sufficient kicker motor.
The Standard Operating Procedure (SOP) for the BRZ will be updated with additional information.
Sequence & Completion Dates for Actions Listed:
Boats were secured at the end of the event. The SOP revision is complete and awaiting management approval.
Lessons Learned:
Recommendations: