The company has been working with King County on the 21km Brightwater Conveyance System, which is part of a USD 1.8bn effort to improve Seattle’s regional sewage treatment system, since 2002.
Jacobs Associates’ role expanded in June 2009 after the Central BT3 Tunnel TBM became lodged 100m below grade, about 3,048m into its 6,096m run. After contract negotiations, an agreement was reached whereby the West BT4 Tunnel TBM would continue past its original end point at the Ballinger Way Shaft to finish the remaining 3,048m of the Central BT3 Tunnel. This work was done under the new BT3-C contract. The final connection of the BT3-C Tunnel and Central BT3 Tunnel was achieved in the third quarter of last year.