On 29 December 2005 in Washington state in the US, King County announced the first construction contract of its new US$1.4bn Brightwater wastewater treatment plant with the award of a US$131M contract that includes 14,000ft of tunnel to a Kenny / Shea / Traylor JV.
The JV will construct a 5.49m diameter tunnel at depths of up to 80m below the surface as part of the final 22.5km of pipeline that will eventually carry treated wastewater to an outfall into Puget Sound. The JV will also construct a 732m long microtunnel.
The 22.5km of pipeline that make up the Brightwater scheme will be built in tunnels ranging from 12m to 134m below the surface. For some parts of the system a single pipe will be installed within the tunnel, other sections will have multiple pipes for delivery and return. Most of the conveyance system will be built using TBMs from four portals.
The construction of the tunnels has been divided into work packages that are scheduled to last from two to four years. T&TI learnt that King County will advertise two more tunnelling contracts in 2006. Total construction cost for the wastewater conveyance system is an estimated $705M. Jacobs Civil is providing construction management services for the conveyance facilities, whilst MWH / Jacobs Associates is designing the system as a joint venture
The scheme is being built to serve parts of King and Snobomish counties in response to increased growth in the region. Currently it is expected that the plant will enter operation in 2010.
