Comparison Of Heat-Pulse Flow Measurements And Vertical Gradients In A Fractured Limestone Aquifer

Establishing a site-specific relationship between heat-pulse flowmeter (HPFM) data and corresponding<br>vertical gradient data may allow prediction of potential vertical gradients through HPFM logging alone.<br>Vertical gradient and corresponding HPFM rates were determined for 117 test intervals in a fractured<br>limestone bedrock aquifer. From these data, it appears that HPFM data can be used in place of more labor<br>intensive borehole packer testing to provide estimates of vertical gradients in this type of hydrogeologic<br>system.<br>Groundwater conditions in the fractured bedrock were investigated through testing of 66 open boreholes,<br>as part of the hazardous waste remedial investigation at the former Loring Air Force Base (LAFB) in<br>northern Maine, USA. Borehole geophysical logging tools, including HPFM and acoustic televiewer<br>(ATV), in conjunction with air hammer drilling logs, were used to target specific fracture(s) to test using<br>conventional straddle packers. HPFM and head data from 41 boreholes met general requirements for<br>comparison purposes, and a linear correlation trend was identified.