1998 Volume 40 Issue 2 Pages 203-224
When released from the ground surface or a source above the capillary fringe, a Dense Nonaqueous Phase Liquid (DNAPL) migrates downwards as a distinct fluid to the fringe. If the rate of the release is relatively low, accumulating and spreading behaviors of the DNAPL upon the fringe will be clearly observed. Such behaviors relate to dynamics of the critical depth of accumulated DNAPL just beyond which the DNAPL starts to finger through the air-water interface (top of capillary fringe). This parameter, in turn, is determined by the threshold entry pressure and water capillary rise height. Many formulas have been developed for estimating capillary rise height and threshold entry pressure, respectively. However, limitations in application are recognized such as some formulas are difficult to apply, others give overestimated results, etc. And a confuse of threshold entry pressure for critical depth may happen because the role of capillary rise height seems to be ignored in all formulations. This paper reports an approach dealing with the problems identified above, in which both the definition and role of all three parameters are made clear, and new formulations are developed to overcome the limitations of available formulas. The approach provides results agreed with experimental results obtained in this study, as well as the data from literature.
