f Application And Comparison Of Methods For Horizontal Flow Measurements In Fractured Bedrock

The ability to measure ambient groundwater flow conditions is a valuable tool in the evaluation<br>of hydrologic properties in environmental and geotechnical studies. Vertical flow characterization<br>methods (spinner flow meter, USGS heat pulse, EM flow meter and Hydrophysical logging) are<br>commonly applied and readily accepted for hydrogeologic and hydraulic evaluation in both fractured<br>and porous mediums. The ability to detect and measure ambient horizontal flow in a wellbore provides<br>a means with which to further define the ambient flow conditions in an aquifer. A family of downhole<br>methods may provide the ability to highly resolve the location of horizontally flowing cells; measure the<br>velocity and direction; and possibly, evaluate the degree to which a fractured flow system behaves in a<br>porous and/or plate/channel flow manner. This enhanced definition could present a means to<br>dramatically improve our understanding of the subsurface flow system and remediation efforts.<br>To evaluate their appropriateness and accuracy, the US Army Environmental Center is presently<br>sponsoring a comparative study of methods to characterize horizontal flow in boreholes. As part of this<br>study, a preliminary field comparison was conducted at two US Army sites (Fort Campbell and<br>Jefferson Proving Grounds) both sited in fractured karst hydrogeologic settings. The methods applied<br>were;<br>1) Hydrophysical logging (HPL)<br>2) Colloidal Borescope Flow Meter (CBFM)<br>3) Acoustic Doppler Velocimeter (ADV)<br>4) K-V heat pulse flow meter (KVFM)