Little is known about the volumetric flux of ground water to the lower tidal Anacostia River, or whether groundwater flow is an important component of the contaminant load in this part of the Anacostia River. The watershed is in the eastern part of Washington, D.C., and has been subjected to over 200 years of urbanization and modifications of the river channel and nearby land areas. These anthropogenic factors, along with tidal fluctuations in the river, make groundwater data collection and interpretations difficult.

Hydrogeologic data were collected from Graces Quarters, Aberdeen Proving Ground, Maryland, as part of a hydrogeologic assessment begun in 1986 to determine the potential environmental effects of military testing and disposal. The U.S. Army conducted chemical-agent and munitions tests in this area from the late 1940's to 1972. This report includes a description of the well network, lithologic, and hydrologic data collected on or near Graces Quarters from April 1987 through April 1989. Observation-well network data include information used for well placement, location and construction data for 32 wells on Graces Quarters, and an inventory of 44 offsite wells. Lithologic data consist of lithologic and geophysical logs and analyses of the physical properties of core sediments. Hydrologic data collected from October 1987 through April 1989 include tables of synoptic measurements and continuous records of groundwater levels, as well as pumpage, aquifer-test, tidal, and precipitation data.) Identify the locations and dimensions of SWMU's and chemical-agent test sites, 2) define the hydrogeologic system, and 3) verify whether SWMU's in the study area have released or are still releasing chemicals into the environment and whether there is residual contamination from chemical-agent testing activities in the study area. Whether or not phase II of the hydrogeologic assessment will be implemented is contingent on the results from phase I. The objectives of phase II of the hydrogeologic assessment are to 1) Further characterize the extent of contamination, 2) identify possible remedial-action alternatives, and 3) evaluate the hydrogeologic effects of various remedial-action scenarios. This report includes information collected for objective two (phase I), which consists of hydrogeologic data compiled from April 1987 through April 1989. Purpose and Scope This report presents hydrogeologic data collected from April 1987 through April 1989 for Graces Quarters. The data include (1) the description of the observation-well networks, (2) lithologic data, and (3) hydrologic data. Twenty-six new observation wells were drilled and used in conjunction with five existing wells (one well, Q04, was never found) to establish a water-level and water-quality network. Lithologic data were collected from 5 test holes and 26 observation wells that were installed in 1988. These data include geophysical logs, lithologic descriptions of split-spoon and continuous core samples, and grain-size analyses from selected lithologic core samples. Data also are presented for slug tests that were performed to obtain an estimate of horizontal hydraulic conductivity at various locations in the Graces Quarters aquifers. Hydrologic data collected included monthly synoptic water levels measured in the wells with chalked steel tapes and continuous water-level data collected from analog to digital recorders (ADR's) that were installed on 11 wells. Data also were collected from a tide gage that was installed near Graces Quarters to help study groundwater and surface-...

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Base-neutral acid extractable BZ: An incapacitating agent (3-quinuclidinyl benzilate) CERCLA: Comprehensive Environmental Response, Compensation, and Liability Act CN: A tear agent (chloroacetophenone) CNB: A tear agent (10-percent CN, 45-percent benzene, 45-percent carbon tetrachloride) CS\ A tear agent (o-chlorobenzylidenemalononitrile) CS-1: CS blended with 5-percent silica aerogel DANC: Decontaminating agent, noncorrosive DM: Adamsite, a vomiting agent (diphenylaminechloroarsine) EA 3990: A nerve agent (no common or chemical name available) EM: Electromagnetic induction FEMA: Federal Emergency Management Agency FWA: Freshwater acute FWC: Freshwater chronic GB: Sarin, a nerve agent (isopropylmethylphosphonofluoridate) GC/MS: Gas chromatography/mass spectroscopy GD: Soman, a nerve agent (pinacolyl methylphosphonofluoridate) HD: Distilled mustard, a blister agent [bis(2-chloroethyl) sulfide]

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