PROJECT COST: $160 million

Bi-County Water Tunnel
Photo: photo courtesy ronald williams, wssc
Bi-County Water Tunnel

Key Facts: Location: Bethesda, Md.
Owner: Washington Suburban Sanitary Commission, Laurel, Md.
Construction Manager: Jacobs Associates, Baltimore; EA Engineering, Science and Technology of Hunt Valley, Md.
Contractor: Renda, Southland, SAK joint venture, a partnership among Oscar Renda Contracting of Roanoke, Texas; Southland Contracting of Fort Worth; and SAK Construction of O�Fallon, Mo.
Start Date: August 2009
Completion Date: 2012

The Washington Suburban Sanitary Commission first identified the need for the Bi-County Water Tunnel, which will transport drinking water from the Potomac Water Filtration Plant to eastern Montgomery County and most of Prince Georges County, in the late 1960s. It has worked since then to bring the $160-million, 5.3-mi tunnel project online. The project broke ground in August. Jacobs Associates leads the construction management team in a joint venture with EA Engineering, Science and Technology.

Renda, Southland, SAK, a joint venture between Oscar Renda Contracting, Southland Contracting and SAK Construction received a $112.5-million contract to construct the tunnel. The bid was 13.4%, $17 million, below the engineering estimate.

Work continues on the main, 150-ft-deep shaft, and crews are blasting to create a second shaft. Work is just beginning on a third shaft. The owner expected tunnel boring to start in late May or early June.

The 7-ft-diameter tunnel will run 150 ft to 300 ft below ground in bedrock. Jacobs indicates that muck handling and ventilation will be more difficult due to the small excavation diameters of about 10 ft.

Jacobs plans two drives, one extending 4,124 ft and the second running 4.5 mi without intermediate access shafts. The project is scheduled for a 2012 completion.