Here is a two lake situation: The upper lake is contaminated with a chemical which has a uniform concentration in the lake for a very long time. The following data applies to a subsurface environment:

C0 =500 g/m3, porosity =0.32, Area of flow: 60 m2 , L=3800 m, h=60 m,

k=10-4.5 m/s, D=10-6 m2/s, Retardation factor R=10.

a) Determine the time of travel of pure water to the lower lake.

b) Modify the Continous Input Solution below for the case of Retardation to use in part c).

c) Calculate the times when a concentration of about 5% and 95% of C/C0 will be noticed coming into the second lake. Comment on your results.