Volume 28, Issue 3 (May 2005)
Sealed Double-Ring Infiltrometers for Estimating Very Low Hydraulic Conductivities
Sealed, Double-Ring Infiltrometers (SDRIs) are one of the preferred devices to measure infiltration rates of soil liners in the field. Existing SDRIs are well suited for measuring infiltration rates on materials with hydraulic conductivities on the order of 1 × 10−9 m/s. A very low hydraulic conductivity material (<1 × 10−10 m/s), such as low-k asphalt concrete, requires some modifications to the existing SDRI designs. A Constant Head Board (CHB) was designed and employed to replace the commonly used flexible bag to accomplish measurement of very small flow increments. Flow increments as low as 0.05 mL can be effectively measured with this technique enabling field hydraulic conductivities as low as 1 × 10−11 m/s and possibly lower to be estimated in a matter of a day or two. The CHB is reliable, follows existing methods, and can account for the effects of temperature and barometric pressure changes on the flow rate.