Problem 3. A non-reactive contaminant is released as a point source into groundwater with an initial concentration of 500 mg/L, and its behavior can be modeled with the 1-D Advection Dispersion equation. If the groundwater velocity is 2.26 x 10^-4 cm/s and the diffusion coefficient is 0.028 cm^2/s, how long (years) will it take for the concentration at a location 200 m directly downstream to reach 300 mg/L?

Fig: 1