USGS Groundwater Information: Hydrogeophysics Branch
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Purpose and Scope
Description of the Study Area
Conventional Geophysical Logging
Cross-Hole Radar Tomography
Azimuthal Square-Array Direct-Current Resistivity Sounding
Analysis of Hydraulic Data
Estimation of Specific Capacity and Transmissivity of Open Boreholes
Estimation of Transmissivity and Hydraulic Head of Fracture Zones
Results: Integrated Interpretation of Geophysical and Hydraulic Logs
Foliation and Fractures
Identification of Large Fractures and Fracture Zones
Azimuthal Resistivity Anisotropy
Results of Hydraulic Analyses
Hydraulic Head and Transmissivity for Individual Open Holes and Fracture Zones
Summary and Conclusions
Appendix 1: Conventional Geophysical Logs from Selected Boreholes at the Study Area,
Appendix 2: Optical Televiewer Logs from Selected Boreholes at the Study Area, Norwalk, Connecticut
Appendix 3: Borehole-Radar Reflection Logs from Selected Boreholes at the Study Area, Norwalk, Connecticut
Appendix 4: Flowmeter Logs from Selected Boreholes at the Study Area, Norwalk, Connecticut
1. Map showing location of the
study area, Norwalk, Connecticut
2. Map showing the study area in Norwalk, Connecticut, with borehole locations, equal-area stereonets showing the orientation of transmissive fractures, and lines representing known hydraulic connections between wells
3. Plot of equal-area stereonets of (a) foliation and (b) fractures, in 11 boreholes at the study area, Norwalk, Connecticut
4. Graph showing fracture intensity for interpreted fractures in 11 boreholes at the study area, Norwalk, Connecticut
5. Plot of caliper, specific conductance, and fluid temperature, under ambient and pumping conditions; modeled flow logs; and estimated fracture transmissivity for borehole MW-69, Norwalk, Connecticut
6. Plot showing locations of transmissive zones in several boreholes, with proposed locations of isolation packers in selected boreholes, Norwalk, Connecticut
7. Graph showing fracture intensity of transmissive fractures in 11 boreholes at the study area, Norwalk, Connecticut
8. Plot of 60-megahertz directional borehole-radar reflection log from borehole MW-71, Norwalk, Connecticut
9. Plot of 100-megahertz cross-hole borehole-radar tomography between boreholes MW-74 and MW-73, Norwalk, Connecticut
10. Graph showing results of azimuthal resistivity, Square Array 1, Norwalk, Connecticut
1. Mean strikes and dips
interpreted at the study area, Norwalk, Connecticut
2. Transmissivity and cross-hole drawdown in selected boreholes at the study area, Norwalk, Connecticut
3. Transmissivity of transmissive zones in selected boreholes at the study area, Norwalk, Connecticut
4. Estimated hydraulic-head difference of transmissive zones in selected boreholes at the study area, Norwalk, Connecticut
Download a PDF version of the main body of the report (1.7 MB PDF)
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Denver, CO 80225
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Citation: Lane, J.W. Jr., Williams, J.H., Johnson, C.D., Savino, Sr. D.-M., and Haeni, F.P., 2002, An integrated geophysical and hydraulic investigation to characterize a fractured-rock aquifer, Norwalk, Connecticut: U.S. Geological Survey Water-Resources Investigation Report 01-4133, 97 p.