Evaluation of Effective Saturation of Air-NLAPL on the Basis of Air-Water Tests in Soils with Multimodal Pore-Size Distribution

This paper was designed to verify if effective saturation distribution for air-LNAPL systems obtained indirectly as suggested by the American Petroleum Institute (2007) are adequate for soils of lateritic nature found in various territories of Brazil. The effective saturation of air-water systems were determined using hanging column tests for typical samples of the state of Sao Paulo (Brazil). These results were then compared to the effective saturations obtained in similar tests for air-LNAPL systems. In both cases, the capillary pressure curves were typical of soils with multimodal pore-size distribution. Moreover, indirect models for effective saturation curves of air-LNAPL were coherent, as long as a tri-modal model was used. Further studies for the prediction of the specific volumes of contaminants in tropical soils are recommended due to the differential retention characteristics.