Damaged TBM stalls Brightwater

A damaged TBM is leading to increased project costs and delays in the construction of the Brightwater sewage treatment plant in Seattle. The TBM was left idle at the site of construction.

The Brightwater sewage treatment plant is now certain to cross the estimated project cost of USD 1.8bn. The project has come to a grinding halt, as project experts are unable to decide how to connect two tunnels of different diameters, one of which has a damaged TBM stuck in it. The damaged machine has been idle near the Lake Forest Park for more than a year.

The Vinci/Parsons/Frontier-Kemper joint venture (VPF) had brought two Herrenknecht TBMs to the site, both of which were damaged after a few months in operation. The TBMs were subsequently shutdown in May 2009. One of the TBMs was repaired and it successfully completed excavation from Kenmore to Bothwell in June 2010. But the second machine has been idle at the site since then.

VPF has been taken off of the project and been replaced by a Jaydee/Coluccio joint venture to complete the job. Planners are now trying to figure out whether they should dismantle and remove the TBM or tunnel around it.