Ultrasonic properties of granular media saturated with DNAPL/water mixtures

Abstract

We present results of four experiments investigating the ultrasonic properties of granular materials partially saturated with trichloroethylene (TCE), a dense non-aqueous contaminant. P-wave velocity measurements were made under in situ effective stress conditions using a pulse transmission cell at ≈250 kHz. Two synthetic samples and two natural aquifer cores were fully saturated with water and then subjected to an axial injection of TCE. The resulting measurements show reductions in P-wave velocity of up to 15% due to contaminant saturation. A theoretical model combining Gassmann fluid substitution and Hill's equation was used to estimate the effects of DNAPL saturation; this model underpredicted observed reductions in velocity at high TCE saturations. A linear relationship, expressed in terms of volumetric contaminant fraction, provided an excellent empirical fit to the laboratory measurements. Copyright 2007 by the American Geophysical Union.