Project: Brightwater Tunnel
Owner: King County, Washington
To help meet growing demands in the Puget Sound region the Brightwater tunnel was built in support of the new regional wastewater treatment plant and conveyance system. The facility features roughly 21 miles of deep effluent tunnel and 7 miles of influent lines, micro tunnels and a deep-water offshore outfall to and from the treatment plant.
The Ballard Hyperbaric Tunnel Support division supported the prime contractor on the “Central Portion” of the project. This work consisted of hyperbaric support services that included manlock operations, providing hyperbaric chambers and associated equipment, in addition to mixed gas delivery system installations on the TBM’s. Ballard provided compressed air workers for both air mode and trimix mode interventions who inspected the tunnel boring machine (TBM) cutting head and tool condition and wear levels.
Our teams certified welders were vital to the successful structural repairs on both TBM’s utilized on this project. During peak intervention cycles, Ballard supported continuous, sustained hyperbaric interventions with up to 15 three person CAW (Compressed Air Worker) teams in rotation, utilizing both trimix and air intervention modes on the two TBM’s simultaneously for periods in excess of six weeks. Ballard provided daily crews of up to 35 onsite personnel.