WSSC Completes 10-Year Long Bi-County Water Tunnel Project

100 Million Gallons of Water Will Flow Through the Tunnel Daily

| News Release



Laurel – March 19, 2015 – After a decade of planning, drilling and digging, the construction stage of WSSC’s Bi-County Tunnel is complete. Two large valves have been opened and the brand new 84” in diameter water main pipeline is officially in service.

The completion of one of the biggest public utility projects in the Washington area marks a significant infrastructure milestone, not only for WSSC but for the 1.8 million residents it serves in Montgomery and Prince George’s counties. The tunnel, which cost a total of $146 million, is the first tunnel built by WSSC in 35 years.

“This project is a tremendous accomplishment that provides an immediate and significant upgrade to our infrastructure” said Jerry N. Johnson, GM/CEO for WSSC. “I would like to commend everyone for the hard work and dedication devoted to this project. The impeccable coordinating efforts between both counties, members of the community and WSSC set the tone for the success of the project.”

“After nearly 5 years in construction, the Commission has opened the tap on the Bi-County Tunnel” said John Mitchel, WSSC Project Manager. “This new 84” transmission main enhances the Commission’s ability to reliably meet current and future water demands in Prince George’s County while maintaining adequate pressures in portions of Montgomery County during extreme demand periods.” 

In addition to providing an increased supply of water throughout the service area, this new water main pipe line increases system redundancy and flexibility. This will allow WSSC to shut down other portions of the distribution system for major infrastructure projects, pipe inspections or during emergency situations like water main breaks and help minimize any disruptions to our customers. 

As economic development and population growth continue in Montgomery and Prince George’s counties so does the demand for water. The 5.3 mile long water line has the capacity to carry 100 million gallons of water daily, greatly increasing water pressure and supply to both counties, ensuring the delivery of water to residents for decades.

The newly installed water main runs along the north side of the beltway connecting two existing water mains at I-270 and Tuckerman Lane to another in Rock Creek Park at Stoneybrook and Beach Drive.

WSSC worked closely with county officials and the Maryland Park and Planning Commission throughout the project in order to minimize community and environmental impacts. Instead of using a traditional cut-and-cover method, WSSC used an alternate plan which led to the design and implementation of tunnel boring for the construction of this tunnel. The tunnel, which runs within solid bedrock between 90 and 280 feet below ground, is an illustration of the impressive engineering feat.

WSSC broke ground on this project in 2009, initially focusing on building two shafts to provide access for the Tunnel Boring Machine (TBM). The main access shaft at Connecticut Avenue was completed first in early 2010, followed by the Stoneybrook shaft and a third one at Tuckerman Lane. In July of 2010, the TBM, also known as “Miss Colleen” took center stage and began chewing through 4000 feet of rock which would eventually create the tunnel for the 84” pipe.

The tunnel boring process was completed in two phases, digging a west and east tunnel. The much anticipated “hole through” of the second tunnel occurred the morning of April 26, 2013.

Additional information and a complete historical overview of the project is available by clicking on the Bi-County Tunnel Water Tunnel Updates page

For 100 years, WSSC has proudly served the citizens of Prince George’s and Montgomery counties – providing drinking water that has always met strict Safe Drinking Water Act standards and protecting the environment through vital water resource recovery services. Our vision is to be THE world-class water utility, where excellent products and services are always on tap.


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