DC Clean Rivers Project – Division P – First Street Tunnel

Project Overview

Part of DC Water’s Clean Rivers Project, the First Street Tunnel provides storage for combined sewage, mitigating surface flooding and sewer backups while reducing overflows into the Anacostia River. The project involved constructing a main tunnel with an earth pressure balance tunnel boring machine (EPBTBM) and extensive community outreach in the historic Bloomingdale and LeDroit Park neighborhoods. The difficult ground conditions required the use of diaphragm walls, secant piles, and ground freezing for support of excavation. The main tunnel was constructed with the use of an earth pressure balance tunnel boring machine (EPBTBM) and supported with a precast concrete segment primary liner. Working within the minimal right of way and around many historic structures in the neighborhood required an extensive community outreach program.