Brightwater tunnel boring machine repair plan in the works

A project to repair Brightwater’s second damaged tunnel boring machine could begin later this month pending permit approval by the City of Lake Forest Park.
 
The machine, called BT-3 or “Rainier”, is currently 300 feet beneath the 19500 block of 53rd Avenue Northeast in Lake Forest Park. The idled machine is about two miles into the nearly four-mile segment of tunnel that terminates at the Brightwater Ballinger Way portal in Shoreline. Because of the location and ground conditions, repairing it in place is the only feasible option.

To simplify repair work and enable crews to work under normal atmospheric pressure deep underground, the contractor is proposing a plan to install a number of dewatering and monitoring wells in the right-of-way on 53rd Avenue Northeast. Performing the work under atmospheric pressure eliminates the need for time consuming decompressions each time repair crew members surface and increases the efficiency of the repair process.
 
The actual repairs to BT-3 will occur underground in the tunnel and could take several months to complete. Workers will access the machine through the North Kenmore portal at the intersection of Northeast 192nd Street and 80th Avenue Northeast.

BT-3 was sidelined in June after inspections revealed wear on the cutterhead’s structural rim. Similar but more extensive damage was detected earlier on Brightwater’s BT-2 machine, nicknamed “Helene”. Repairs on BT-2 began in June and are expected to conclude this fall.  (More information on BT-2 is available at http://www.kingcounty.gov/environment/dnrp/newsroom/newsreleases/2009/june/0608Tunnel-machine-repairs.aspx)

Construction on the central six-mile portion of the Brightwater tunnel will resume as soon as repairs are completed on at least one of the machines. Joint venture contractor Vinci/Parsons/Frontier-Kemper will be able to recall laid off workers at that time.  
 
More information about the Brightwater Project is available at http://www.kingcounty.gov/brightwater.
Note to editors and reporters: Visit the WTD Newsroom, a portal to information for the news media about the Wastewater Treatment Division, King County Department of Natural Resources and Parks: http://www.kingcounty.gov/environment/wtd/Newsroom.aspx.

Related information

Brightwater Treatment System

King County Wastewater Treatment Division