5.21. Underground Chemical Release Suppose that a mass m of a volatile organic liquid (e.g., gasoline) is known to have leaked from an underground tank. As a first approximation, it is proposed to model the dispersion of the organic as diffusion from an instantaneous point source at t=0 and a depth L. It is supposed that evaporation will keep the concentration at ground level negligible, with coordinates as in Fig. 5-12. According to this possibly oversimplified model, all of the contaminant will evaporate eventually. The concentration and flux of the organic in mass units are denoted as and n, respectively. (a) Use the method of images to find (x,y,z,t). (b) Calculate the upward flux at the surface, n0(x,y,t), and the fraction of the leak that remains in the ground, F(t). 5.21. Underground Chemical Release Suppose that a mass m of a volatile organic liquid (e.g., gasoline) is known to have leaked from an underground tank. As a first approximation, it is proposed to model the dispersion of the organic as diffusion from an instantaneous point source at t=0 and a depth L. It is supposed that evaporation will keep the concentration at ground level negligible, with coordinates as in Fig. 5-12. According to this possibly oversimplified model, all of the contaminant will evaporate eventually. The concentration and flux of the organic in mass units are denoted as and n, respectively. (a) Use the method of images to find (x,y,z,t). (b) Calculate the upward flux at the surface, n0(x,y,t), and the fraction of the leak that remains in the ground, F(t)