A New Versatile Design for Automated Tension Infiltration

Numerous studies in recent years have addressed in situ measurement of soil hydraulic retention and conduction parameters using tension infiltrometers. While convenient for field use and easy to set up, several problems exist with the long-standing design that utilizes an attached bubbling column to maintain supply tensions at the soil interface (Perroux and White,1988). In an attempt to better meet the demands of field work several improvements have been made to make the tool easier to use and more reliable. Elements of the development include an internal reference column for maintaining constant tension, high precision pneumatic valves computer-regulated to let air into the supply tower, and a durable stainless steel supply membrane designed to withstand harsh field conditions with bubbling pressure exceeding 40cm of tension. The instrument is fully controlled through a user-friendly control unit that enables the researcher to stipulate the conditions of each infiltration that must be run; a series of infiltrations at multiple tensions without having to adjust any vales or refill the supply tower; and the porous membrane is now durable enough to last for hundreds of measurements without replacement. Software was also developed for efficient data transfer and interpretation. Preliminary experiments with this novel design indicate its practicality in most geophysical settings, and further opportunities for advancement are identified.