The District of Columbia Water and Sewer Authority (aka DC Water) is implementing the Clean Rivers Project: a 20-year, $2.6 billion effort to reduce discharges from combined sewer overflows into the Potomac and Anacostia Rivers. This project, which involves 14 separate division contracts, includes over 12 miles of storage and conveyance tunnels with associated shafts, pump stations, overflow facilities, and diversion chambers. The first major Division A contract—the Blue Plains Tunnel—is a 4.6-mile, 23-foot-diameter tunnel. There are three other primary tunnel segments included in the overall project.
Schnabel is a key member of the “General Consultant for Tunneling and Geotechnical Engineering” team that addresses geotechnical issues during design, procurement and construction. Our contributions include leading geotechnical engineering investigations, analyses, and recommendations; preparing geotechnical data and baseline reports; conducting soil and water contamination assessments; and performing pump testing and hydrogeological analyses.
During procurement our risk management team is also responsible for the risk management effort for all 14 divisions. This includes qualitative risk analysis and development of risk registers to identify, characterize, and mitigate potential risks for each project. For the four major tunnels, we prepared a probabilistic quantitative analysis of potential risk events to enable DC Water to establish budgetary contingency amounts.