A constant-head pumping test method using direct-push equipment for in situ hydraulic conductivity measurements

A novel direct-push (DP) probe was developed for in situ hydraulic conductivity measurements in unconfined sandy aquifers. It is a small-diameter tool with an intake screen and a built-in pressure transducer, and is directly pushed into the ground. Hydraulic conductivity k is estimated by pumping from an aquifer through the intake screen and, while doing so, measuring flow rate and water pressure. This paper describes first the DP system and then the procedures for estimating k values. The finite-element method was employed to obtain intake factors that correlate the measurements with the k values, and these intake factors were compared with those proposed for conventional borehole packer tests. Laboratory and field experiments were also performed to assess the usability of the DP equipment. The results showed that the k estimates obtained from the new probe agreed with those obtained by other methods. The results of this assessment indicate that the proposed DP technique is a promising tool for simple and rapid in situ measurements of hydraulic conductivity. Limitations to the technology are discussed, and further work is suggested.