By rosebell
With the aim of creating two TBM launch shafts, underground blasting is going to begin on DC Water’s Potomac River Tunnel project this week and this blasting process at the West Potomac Park construction site will continue per week through to February 2026.
In order to lowering and starting up two 6.4m-diameter TBMs, this blasting operations are part of constructing two 31.4m-deep mining shafts.
This 8.9km tunnel is due to be constructed by Herrenknecht machines. While one TBM is slated to excavate north, boring through rock to the endpoint at Georgetown University’s entrance on Canal Road Northwest, moving south to the Joint-Base Anacostia Bolling (JBAB) site, where the Potomac River Tunnel links with the Anacostia River Tunnel, will be up to the other one. The delivery time of TBM Mary, which will dig north and recently passed the Factory Acceptance Test in Germany to the West Potomac Park site is autumn this year. The second TBM, called Emily, will be delivered in 2026.
Including a large-diameter, deep sewer tunnel, diversion facilities, drop shafts, and support structures, DC Water’s Clean Rivers Project’s next major phase is the Potomac River Tunnel. The tunnel system will capture the combined overflow of wastewater and stormwater during major weather events until it can be released to the Blue Plains Advanced Wastewater Treatment Plant instead of being discharged into the Potomac River.
For improving the water quality of the Potomac River and, ultimately, Chesapeake Bay, the project is needed to reduce the sewer overflows.
Considering the situation that the rainfall exceeds the sewer system’s capacity, the overflow is released at outlets into the Potomac River, impacting water quality and so an estimated 654 million gallons of mixed stormwater and sewage overflows enter the Potomac River in a year of average rainfall. The proposed controls are estimated to reduce the volume of untreated wastewater released into the Potomac River by 93% and reduce the frequency from approximately 74 events to only four in a year of average rainfall.
