DALLES DAM

United States Army Corps of Engineers (USACE) personnel access the top of the approximately 30 electrical power transformers at The Dalles hydroelectric dam. Workers use a ladder to climb the 15 feet transformers and are exposed to a fall hazard while performing maintenance.

Dalles Dam

ENGINEERING

United States Army Corps of Engineers (USACE) personnel access the top of the approximately 30 electrical power transformers at The Dalles hydroelectric dam. Workers use a ladder to climb the 15 feet transformers and are exposed to a fall hazard while performing maintenance.

CHALLENGES

The freestanding transformers are located outside on top of the dam, eliminating the possibility of workers attaching to overhead structures with conventional fall protection devices. Tight grouping of the transformers prevents the ability of a portable gantry system. Safeguards needed to be made to prevent an arc-flash incident. Welding to the transformers was not a preferred solution due to damage concerns, so davit bases were ruled out.

SOLUTIONS

Gravitec designed and fabricated two completely different extensible systems that are permanently affixed to the concrete deck on each side of the transformer. One design featured a horizontal lifeline that disconnected during raising and lowering of the system. The extensible system could easily be lowered and stowed in the retracted position. Another design featured a rigid rail system that could be raised when needed and then stowed away in a matter of minutes. Arc-flash hazards were mitigated by a comprehensive safety plan, outlining fall protection procedures for maintenance personnel.

END RESULT

Gravitec was able to deliver a user-friendly design that allowed for minimal task interference and offered 100% fall protection from the ground up. This design, uniquely for transformers, allowed workers the ability to safely perform their tasks while securely attached to the extensible rigid rail or horizontal lifeline system.

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