Potomac River Tunnel Project

EBA completed a customized Phase I Environmental Site Assessment (ESA) to support development of an Environmental Impact Statement of the Potomac River Tunnel study area in Washington, DC. This project is part of DC Water’s Clean Rivers Initiative to control combined sewer overflows to the Anacostia River and mitigate flooding in the Northeast Boundary area of Washington, DC.

EBA assessed 7 proposed areas, totaling approximately 64 acres, for the construction of tunneling shafts and the more than 5-mile proposed tunnel alignment route. Services for the customized Phase I ESA included examining regulatory databases for documented sources of environmental impact; reviewing historic fire insurance maps and aerial photographs to identify land uses likely to result in environmental impacts; inspecting the proposed surface disturbance areas; and preparing a report of findings, including opinions and conclusions related to sources of potential environmental contaminants within the tunneling and construction areas.

The irregular shape, size, and configuration of the study area in a dense, urban setting of high tourism activity required scope of work customization and the use of multiple investigative methods and research levels.

EBA also conducted a desktop review of groundwater, geology, and soils in the study area. Work included reviewing published geologic reports and previous investigations to determine subsurface conditions; performing site reconnaissance to evaluate general site topography and drainage conditions; preparing generalized geologic cross-sections and analyzing subsurface soil and groundwater information; and drafting a technical memorandum including a summary of the generalized existing conditions.