USGS Groundwater Information: Branch of Geophysics
John H. Williams, U.S. Geological Survey
Frederick L. Paillet, U.S. Geological Survey
Flow zones in a fractured shale in and near a plume of volatile organic compounds at the Watervliet Arsenal in Albany County, N. Y. were characterized through the integrated analysis of geophysical logs and single- and cross-hole flow tests. Information on the fracture-flow network at the site was needed to design an effective groundwater monitoring system, estimate offsite contaminant migration, and evaluate potential containment and remedial actions.
Four newly drilled coreholes and four older monitoring wells were logged and tested to define the distribution and orientation of fractures that intersected a combined total of 500 feet of open hole. Analysis of borehole-wall image logs obtained with acoustic and optical televiewers indicated 79 subhorizontal to steeply dipping fractures with a wide range of dip directions. Analysis of fluid resistivity, temperature, and heat-pulse and electromagnetic flowmeter logs obtained under ambient and short-term stressed conditions identified 14 flow zones, which consist of one to several fractures and whose estimated transmissivity values range from 0.1 to more than 250 feet squared per day.
Cross-hole flow tests, which were used to characterize the hydraulic connection between fracture-flow zones intersected by the boreholes, entailed (1) injection into or extraction from boreholes that penetrated a single fracture-flow zone or whose zones were isolated by an inflatable packer, and (2) measurement of the transient response of water levels and flow in surrounding boreholes. Results indicate a wellconnected fracture network with an estimated transmissivity of 80 to 250 feet squared per day that extends for at least 200 feet across the site. This interconnected fracture-flow network greatly affects the hydrology of the site and has important implications for contaminant monitoring and remedial actions.
Download Adobe Acrobat PDF version of Open-File Report 01-385 (1.4MB PDF).
free Adobe Acrobat Reader to view PDF files at the Adobe web site.
Visit http://access.adobe.com for free tools that allow visually impaired users to read PDF files.
Citation: Williams, J. H. and Paillet, F. L., 2002, Characterization of fractures and flow zones in a contaminated shale at the Watervliet Arsenal, Albany County, New York: U. S. Geological Survey Water-Resources Open-File Report 01-385, 26p.