Boundary Dam Rockfall Mitigation

The Boundary Dam Complex produces more than 50 percent of Seattle’s electricity. Its transmission lines — which exit through transformer bays at the bottom of a 500-foot cliff — had in recent history received damage from rockfall. To keep the problem from worsening, Seattle City Light put $20 million towards finding a long-lasting solution.

Long-Term Protection

Kleinfelder’s team developed four mitigation options—ranging from rock anchors and netting to rock deflection sheds to a new tunnel—for long-term protection of Seattle City Light’s transmission lines, all of which would reduce the potential for damage and power outages.

• Project Overview