As noted here previously, PSE ‘s “all-wires-overhead-all-the-time” tunnel vision excluded from its consideration all undergrounding options when it pre-selected the only two routes currently put before the public. PSE also chose to ignore another 21st century solution: Putting the lines underwater in a submarine cable.
San Francisco, for example, will start placing a 13.5 km-long cable with 230kV lines through the San Francisco Bay that will be completed in July 2015 at a cost of $37 million. That comes to $4.4 million/mile, vastly cheaper than the unsubstantiated $25 million per mile PSE has been touting for undergrounding lines in its Energize Eastside project.
Underwater cables containing high-voltage power lines are not new to King County. We already have an underwater line from Renton to Mercer Island, and another one from Des Moines to Vashon Island to Kitsap County that provides the Vashon Island with all its electricity.
Nor are the above-mentioned submarine solutions unique phenomena. Here’s a link to an impressive list of several existing submarine cables around the world and many proposed ones as well: http://en.wikipedia.org/wiki/Submarine_power_cable. The San Francisco submarine cable has yet to be added to the list.