Taming the Multi-Stakeholder Hydra: Permitting, Design, and Tunneling a Sewer across the Dulles International Airport and the Metrorail Silverline

This case study will discuss the intricacies in planning, designing, permitting, and constructing a large-scale gravity sewer across the Dulles International Airport and with four tunneled crossings of the Washington Metropolitan Area Transportation Authority’s Metrorail Silverline (Phase 2). The sewer was designed to serve Loudoun Water in Loudoun County, VA. Located just west of Washington, DC, in one of the fastest growing areas in the country, this new sewer is needed to meet Loudoun’s projected wastewater demands in their Horsepen Run sewershed. This paper will outline the strategies implemented by the project team to facilitate and expedite stakeholders review and approval of the 20,000 linear-foot large diameter sewer (72/48/42 inch). In addition, the paper will outline how the scalable risk management strategy employed aided in maximizing value for Loudoun Water while minimizing risk.