Reporter staff

A second tunnel-boring machine building the central portion of Brightwater’s 13-mile conveyance tunnel has been temporarily idled to enable needed repairs and maintenance, according to information released by the King County Wastewater Division.

Brightwater is a regional wastewater treatment plant that will service portions of King and Snohomish counties.

Detailed inspections on BT-3, or “Rainier,” performed in the wake of problems that sidelined Brightwater tunnel machine BT-2 several weeks ago, revealed similar but less extensive damage to the cutterhead’s structural rim.

Construction at the north Kenmore portal work site will be suspended for several months, prompting a decision by joint venture contractor Vinci/Parsons/Frontier-Kemper to lay off an additional 67 workers, about half of its remaining work force. The workers will be recalled when construction resumes.

BT-3 began tunneling west from the Brightwater north Kenmore portal, located near the intersection of 80th Avenue Northeast and Northeast 195th Street, in late fall 2007. The machine is currently 330 feet underground and has completed about two miles of the nearly four-mile segment of tunnel that terminates at the Brightwater Ballinger Way portal, located just north of 19th Avenue Northeast in Shoreline.

The contractor is currently developing plans to repair the BT-3 tunnel-boring machine. No specific details are available at this time. The county has proposed digging six narrow wells to help repair the BT-2 machine, which sits near Maywood School in Bothell. The wells and their potential nearness to the school attracted some negative attention and sparked a recent community meeting.

In their release regarding the latest drill problems, officials said that despite repair work and construction downtime, the county still expects to begin start-up and testing of the new Brightwater facilities by mid-2011.

More information about the Brightwater Project is available at http://www.kingcounty.gov/brightwater.