The Kow for carbon tetrachloride is 220. Using the rule of thumb that log(Koc) = .8*log(Kow), and assuming an organic carbon content of 1% you can estimate the retardation factor for carbon tetrachloride. Remember that porosity is 15% and assume a dry bulk density for the soil of 2.2 g/cm^3. How long would it for this contaminant to reach the creek. Creek is 3000ft away. Hydraulic gradient is .0667. Average linear velocity is 8.89m/s.