Preferential flow and entrapment of nonaqueous phase fluids in water saturated heterogeneous porous media
- Univ. of Colorado, Boulder, CO (United States). Dept. of Civil, Environmental and Architectural Engineering
Subsurface stratigraphy plays an important role in the migration and distribution of chemical and waste products that are in the form of nonaqueous phase liquids (NAPL). In the saturated zone, coarse layers act as preferential flow channels and as pockets for fluid entrapment. The entrapment saturations resulting from these macro-scale soil heterogeneities are much larger than the residual saturations controlled by the micro-scale pore characteristics of the soil. The phenomena of preferential flow and macro-scale entrapment have been observed in the authors` laboratory spill simulations and in the field. It is their hypothesis that they are caused by the capillary barrier effects existing at the interfaces of the coarse and fine sand formations. Precision flow experiments were conducted in soil cells to obtain quantitative data to understand the nature of these capillary barrier effects. A complete testing program was implemented with five sands using both air and a light NAPL as the non-wetting phase. The experimental design and the results are presented. The experimental results are used to identify the characteristics of the soils in layered aquifers that produce barrier effects. The results of this study will help in developing field characterization techniques to determine soil parameters needed in modeling nonaqueous phase fluid flow and entrapment in heterogeneous aquifers. This knowledge will also be useful in the design of fine soil barriers for the containment of plumes and coarse soil traps for the recovery of waste fluids.
- OSTI ID:
- 491010
- Report Number(s):
- CONF-9406250-; TRN: IM9729%%261
- Resource Relation:
- Conference: 9. Annual conference on hazardous waste remediation, Bozeman, MT (United States), 8-10 Jun 1994; Other Information: PBD: 1994; Related Information: Is Part Of Proceedings of the 9. annual conference on hazardous waste remediation; Erickson, L.E.; Tillison, D.L.; Grant, S.C.; McDonald, J.P. [eds.]; PB: 389 p.
- Country of Publication:
- United States
- Language:
- English
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