Rehabilitating a Critical Large Diameter Sewer Under a Levee and a Historic Park

This paper describes how the Washington Suburban Sanitary Commission (WSSC) supported the spiral-wound lining of its 2.6-meter (102-inch) Anacostia Trunk Sewer (ATS) by maximizing use of existing infrastructure to bypass up to 378,540 m3/day (100 million gallons per day) of wastewater. This paper also describes how WSSC structured the construction contracts for this work to maximize bidder interest while using a proprietary rehabilitation technology. Both of these topics will help other utilities learn how to make their own trenchless rehabilitation projects more affordable and technically feasible.The ATS is the largest, most critical pipe in the Washington Suburban Sanitary Commission (WSSC)’s collection system. WSSC directed rehabilitation of the ATS after a condition assessment identified significant hydrogen sulfide corrosion damage in the pipe and a structural evaluation determined that it was overstressed and at the end of its service life. The rehabilitation was constrained by the fact that approximately 518 linear meters (LM) (1,700 linear feet) of the ATS runs under a levee along the Anacostia River and under the historic Bladensburg Waterfront Park, site of the Battle of Bladensburg in the War of 1812.WSSC negotiated a price for the proprietary SPR rehabilitation and included it in the bidding documents to maximize the interest of general contractors who may have been concerned about being able to submit competitive bids. WSSC also procured the 2.44 meter (96-inch) gate valve, to be installed as part of the bypass system, ahead of the rest of the rehabilitation to ensure that it was ready when the rehabilitation contractor received its Notice to Proceed.