PIPPIN, CHUCK, chuck.pippin@ncmail.net, HELLER, MATT, matt.heller@ncmail.net, NCDENR, Groundwater Section, Mooresville, NC; and MEW, TED, ted.mew@ncmail.net, NCDENR, Groundwater Section, Raleigh, NC

In the fall of 1997, the Groundwater Section of the North Carolina Department of Environment and Natural Resources, Division of Water Quality conducted a hydrogeologic study near Pasour Mountain, in northwestern Gaston County, North Carolina. The primary goals of the study were to determine local aquifer characteristics and to characterize the hydraulic relationship between shallow and deep portions of a saprolite/fractured-bedrock aquifer. The study involved the installation of a monitoring well network, detailed geologic mapping, and a 39 hour aquifer test.  The monitoring well network was constructed in a trilinear grid centered on a pumping well.  The east-west axis of the grid parallels an intermittent stream.  The stream parallels observed E-W trending fracture sets. The dominant rock type near the test site is a layered white mica to quartzofeldspathic schist with a well-defined foliation typically striking NNE and dipping steeply to the west.  Trends of observed non-penetrative joints and fractures range from E-W to WNW and have moderate to subvertical dips. The aquifer test was conducted at an 18 gpm pumping rate with the pump set within the zone of transition between the saprolite and bedrock portions of the aquifer. Results of the aquifer test returned initial drawdown responses (IDR) that define an elliptical drawdown generally oriented E-W. The initial E-W response is quickly superceded by an elliptical drawdown generally oriented N-S. Examination of the IDR times suggests that site hydraulics are structurally controlled. One possible explanation for this transition is initial dewatering of a local fracture controlled transition zone followed by recharge through groundwater draining from the overlying saprolite. Theis approximations for an unconfined aquifer were used to determine the transmissivity and storativity of the aquifer test wells.  Analyses of the data indicate transmissivities that range from 0.002 to 0.004 square feet/sec and storativites between 9.95x10-6 to 3.7x10-3.  The individual transmissivity values were used to graphically determine the orientation of the transmissivity ellipse.  The major axis of the transmissivity ellipse has a NNE orientation and is in general agreement with the regional foliation.