Factors Affecting Field‐Saturated Hydraulic Conductivity Measured by the Borehole Permeameter Technique

Abstract The borehole permeameter method for measuring field‐saturated hydraulic conductivity, K fs , is prone to variability due to soil smearing during borehole excavation, and swelling that results from differences in initial soil‐water content. The effects of borehole preparation techniques and initial soil‐water pressure on K fs were analyzed in this study. Eighty boreholes were studied in a strongly structured clayey soil (a fine, mixed, mesic Typic Hapludalf). A version of the borehole permeameter method was used to measure K fs in soil that was initially at soil‐water pressures of 0, −0.016, −0.050 and −0.080 MPa. Three different borehole excavation techniques were also studied to determine the effect on K fs of soil smearing during borehole preparation. The treatments consisted of removing a uniform thickness of soil from the sides of the borehole with an ice pick, scarifying the sides of the borehole with a wire brush, and no treatment. Field‐saturated hydraulic conductivity for the brushed treatments was similar to K fs values obtained when no treatment was used. The ice pick method resulted in significantly higher K fs . When K fs values measured using the ice pick method were analyzed, no significant effect of initial soil‐water pressure was evident. This could possibly be due to soil variability.