Anacostia Groundwater Study

Objectives

The overall goal of the proposed project is to develop an understanding of the hydrogeologic framework, to determine the extent of Groundwater / surface-water interactions, and to estimate the contributions of contaminants from the Groundwater to the lower tidal Anacostia River in Washington, D.C.

Statement of Problem

The Anacostia River has been subjected to dredging, filling, contamination, and other human influences for over 200 years. The result of these activities is that the river has been seriously degraded from its natural state. Many groups have been working to reduce the effects of environmental degradation on the water quality and living resources of the Anacostia River, primarily by focusing on toxic contamination in river sediments. Other sources of contaminants to the Anacostia, including those from combined sewage outfalls and from Groundwater, are beginning to attract attention from investigators interested in addressing the environmental problems in the area.

Groundwater hydrogeology in the lower Anacostia tidal watershed is not well characterized, and is possibly a source of contaminants to the river. Because of the urban nature of the watershed and the long history of industrial and residential development in the area, it is likely that Groundwater in the area is contaminated. However, little is known about the types of non-point source contaminants in the Groundwater, the characteristics of Groundwater flow, or the volumetric flux of Groundwater and associated contaminants to the river. Because of the many modifications to the river system (including bulkheads, dredging, filling, engineered wetlands, storm drains, and leaky infrastructure), Groundwater interactions with the river are complex and difficult to characterize. It is therefore important to use a wide variety of investigative tools to help characterize the Groundwater flow system, the Groundwater quality, and the ground- and surface-water interactions.

Strategy and Approach

Develop a series of hydrogeologic cross sections in the lower Anacostia tidal watershed.

Drill new wells and inventory existing wells to be used as part of the Groundwater monitoring network in the lower Anacostia watershed.

Borehole geophysical data (gamma logs) will be collected for each well that can be accessed by the appropriate equipment.

Collect water-level data and determine aquifer properties in new and existing monitoring wells using single-well slug tests or multi-well pumping tests.

Collect water-quality data from wells. Constituents, will include VOCs, semivolatiles, pesticides, PCBs, total metals, mercury, total cyanide, total phenols, total suspended solids, total dissolved solids, chemical oxygen demand, BOD, oil and grease, TKN, and nutrients.

Evaluate Groundwater contaminant loads to the lower Anacostia River.