PacifiCorp breaches 14.7-MW Condit Dam, opening White Salmon River

WHITE SALMON, Wash., U.S. 10/27/11 (PennWell) — With a muffled roar and a puff of pulverized concrete, PacifiCorp blasted open 14.7-MW Condit Dam on Oct. 26, ending nearly a century of power generation and opening 33 miles of Washington’s White Salmon River to steelhead and salmon migration.

The Federal Energy Regulatory Commission accepted PacifiCorp’s surrender of its license for Condit Dam in 2010 and approved the utility’s plan to remove the dam, 19 years after PacifiCorp attempted to relicense the project. Resource agencies and groups, including American Rivers, pushed for decommissioning and removal of the dam because it cut off salmon and steelhead from the White Salmon, a Columbia River tributary, for nearly a century.

In a settlement with resource agencies and stakeholder groups, PacifiCorp agreed to remove Condit Dam and to decommission the project rather than spend an estimated $30 million to install fish ladders that would be required for relicensing.

“We are sad to lose this emission-free source of power,” President Micheal Dunn of PacifiCorp Energy said. “But we made a decision to work with our settlement partners to come to the most reasonable solution for everyone involved, especially the cost to our customers.”

The cost of decommissioning and removing Condit is currently estimated at about $33 million, including funds already spent during the planning process over the 12 years since the settlement was originally announced.

Crews worked throughout the summer preparing to blast the 13-foot-wide hole near the base of the 125-foot-tall, 471-foot-long concrete gravity diversion dam. During August and September, crews excavated a 90-foot-long drain tunnel through the dam. Other work included dredging the upstream side of the dam at the drain tunnel, strengthening a bridge that crossed Northwestern Lake, and relocating a water pipeline that crossed the reservoir.

PacifiCorp, prime contractor JR Merit, and detonation contractor Kiewit Infrastructure West, both of Vancouver, Wash., surveyed the area after the blast, took readings from sensing devices, and flew over the area in a helicopter before declaring the breach a success and the remaining structure to be safe.

The waters of the 1.8-mile-long Northwestern Lake poured through the breach, draining over six hours. Fisheries biologists had already moved more than 500 salmon from above the dam. Their offspring are to be returned to the river.

Demolition of the remaining portion of the dam is scheduled to begin in spring 2012 and be completed by August 31, 2012. Restoration work throughout the former reservoir area is slated for completion by the end of 2012.

PacifiCorp said there are no plans to dismantle the powerhouse, which was built in 1913. The plant was shut down just before the Oct. 26 blast.

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