Montgomery and Prince George's Counties, MD
Nobis Engineering provided civil inspection and project coordination support during the construction management phase of the Washington Suburban Sanitary Commission's new 5-mile-long water line in Montgomery and Prince George's Counties, MD. The $146 million project involved the building of a 10-foot-diameter, 170-foot-long shaft seen in the photo, as well as two additional shafts. The main, which connects two existing 96-inch diameter pipes in Montgomery County, is part of a transmission system that onnects the potable water system from WSSC’s Potomac Treatment Plant to Prince George’s County. The tunnel capacity is more than 100 million gallons of water per day.
Groundwater encountered during construction was treated at an onsite water facility which treated about 900 gallons of water per minute.
The owner, Washington Surburban Sanitary Commission, worked with Maryland-National Capital Park and Planning Commission on a stream restoration project related to the construction of the shafts, and coordinated with Maryland State Highway Administration on right-of-way permits.
In 2016, the Bi-County Water Tunnel project was awarded Project of the Year by American Society of Civil Engineers' National Capital Section.