Date of Award

Fall 1994

Document Type


Degree Name

Master of Science (MS)


Ocean & Earth Sciences



Committee Director

G. Richard Whittecar

Committee Member

Joseph H. Rule

Call Number for Print

Special Collections LD4331.G4R87


At a 500 acre site in Henry County, Virginia, differences in vertical hydraulic conductivity (KV) and lateral hydraulic conductivity (KH) measured in saprolites formed from the Fork Mountain biotite gneiss and the Leatherwood granite reflect the control of the fabric, texture, and structure of the parent rock preserved within the saprolite horizon. Using subsurface data collected from approximately 350 boreholes in conjunction with published information enabled various maps to be generated that identify the spatial relationships between geology and topography and their influence on the nature of the saprolite aquifer.

Measurements of KH determined from multiple bail tests reveal a range of hydraulic conductivity values for each formation. Using T-tests indicates that the mean conductivity values for the slug test data populations are significantly different (a.= 0.05).

Permeameter tests show variation in vertical conductivity (Kv) within each and between the two saprolite formations. For both formations, Kv increases with depth due to the decline of soil clay. Differences between formations result from standard laboratory procedures that permit the preserved high angle foliation within the saprolite of the Fork Mountain biotite gneiss to inhibit vertical flow.

Pump test data for both formations indicate that the fabric and texture of the parent rock preserved within each saprolite often influence groundwater flow. However, secondary porosity formed from weathering (e.g. macropores) and structural (e.g. fractured quartz veins) features within each formation may overshadow the primary saprolite porosity.

Recovery test data correlate with slug test data in showing that significant variation exists between measurements of lateral hydraulic conductivity (KH) for both formations.


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