BPA plans line route through county

Agency hopes to avoid taking homes while easing congested transmission

The Bonneville Power Administration is planning a new 70-mile-long transmission line through Clark County, connecting major new substations in Castle Rock and Troutdale, Ore.

The federal power marketing agency, which controls about three-quarters of the Northwest’s transmission grid, is holding a series of six open houses beginning today to introduce several alternative routes for the new line and take questions and comments.

After analyzing the alternatives, Bonneville plans to make a final decision in 2012, with construction following sometime after that.

Energy officials believe the 500-kilovolt line is necessary to ease transmission system congestion in northwest Oregon and Southwest Washington. The total cost is unknown, but project manager Mark Korsness said the cost would run into the hundreds of millions of dollars. Earlier this year, the BPA got an additional $3.25 billion in borrowing authority to upgrade the region’s transmission grid.

The BPA has drawn several proposed routes for the line, including the possibility of simply adding parallel lines on existing Bonneville right-of-way.

“One of our main goals was to try to develop routes that avoided taking any homes,” Korsness said. “Not that at some point we won’t decide to try to purchase one or more homes, but we’re trying very hard to avoid that.”

Transmission lines are imposing. A line includes a series of lattice steel towers, spaced 1,000 to 2,000 feet apart depending on terrain. Nine wires, in bundles of three, carry electricity. Two additional overhead “ground” wires protect against lightning strikes.

The towers are typically 80 to 150 feet tall.