PHYSICAL AND MATHEMATICAL-MODELING OF DIESEL FUEL LIQUID AND VAPOR MOVEMENT IN POROUS-MEDIA

Two-dimensional physical modeling of diesel fuel leaks was conducted i n sand tanks to determine liquid and vapor migration characteristics. Mathematical modeling provided estimation of vapor concentrations at d iscrete times and distances from the vapor source and was compared to the physical experiment. The mathematical gaseous diffusion model was analogous to the Theis equation for ground-water flow, accounted for s orptive effects of the media, and was calibrated using measured concen trations from the sand tank. Mathematically different positions of the vapor source were tested to better relate observed liquid flow rates and media configuration to gaseous concentrations. The calculated diff usion parameters were then used to estimate theoretical, three-dimensi onal vapor transport from a hypothetical liquid leak of 2.0 1/hr for 3 0 days. The associated three-dimensional vapor plume, which would be r easonably detectable by commercially available vadose zone monitors, w as estimated to have a diameter of 8 m with a vapor concentration of 5 0 ppm at the outside edge of the vapor plume. A careful application of the method and values can be used to give a first approximation to th e number of vapor monitors required at a field site as well as the opt imal locations for the monitors.