Comparing Petroleum and Water Hydraulic Properties in Soil

In order to assess hydraulics of LNAPLs in soil، the soil retention curves of petroleum and water were both determined through hanging column method. And، the hydraulic conductivity of petroleum and water were determined by steady head method. The water and petroleum hydraulic conductivities were 7. 27 and 57. 84 cm. day-1، respectively. The soil retention parameters were obtained based on van Genuchten، Brooks-Corey and Campbell models. In addition، the soil hydraulic conductivity for both fluids was predicted based on Mualem- Brooks-Corey، Burdine- Brooks-Corey، Mualem-van Genuchten and Campbell models. The accuracy assessment of models was performed by ME، RMSE، CD، EF and CRM. The results indicated that the magnitudes of the pore-size distribution parameters and the bubbling pressure parameters were reduced in NAPL-air system compared to water-air system. Due to unusual hydraulic behavior of petroleum and soil-petroleum interactions leading to remaining substantial petroleum content in porous media، more matric potential is needed to drain out petroleum from soils compared to water. Thus، soil provides more retention for petroleum at a given quantity of fluid. Owing to high amount of petroleum kinematic viscosity، the saturated soil hydraulic conductivity of petroleum was lower than that of water. However، soil hydraulic conductivity for petroleum was larger than water at more than 100 cm matric head.