EBA completed a customized Phase I environmental site assessment (ESA) to support the preparation of an environmental assessment of the Potomac River Tunnel study area in Washington, DC. This project is part of DC Water’s Clean Rivers Initiative and is designed to control combined sewer overflows to the Anacostia River and to mitigate flooding in the Northeast Boundary area of Washington, DC. Specifically, EBA assessed seven proposed areas of surface disturbance (for construction of tunneling shafts) totaling approximately 64 acres and the proposed tunnel alignment route, which is longer than 5 miles.
EBA reviewed regulatory databases to identify documented sources of environmental impact, reviewed historic fire insurance maps and aerial photographs to identify land uses likely to result in environmental impact, conducted physical inspections of the properties, and prepared a report of findings.
EBA also conducted a desktop review of existing conditions in the study area related to groundwater, geology, and soils. EBA reviewed published geologic reports and available records of previous investigations to determine subsurface conditions; performed site reconnaissance to evaluate general site topography and drainage conditions at the study area; prepared working generalized geologic sections and analyzed subsurface soil and groundwater information; and prepared a technical memorandum including a summary of the generalized existing conditions.