The Ogata-Banks calculator
solves the 1D advection dispersion equation using the
Ogata-Banks solution. The input for the calculator
includes a time of interest, location of interest (distance from
the source) and a source concentration, in addition to the
transport properties of velocity, dispersion and retardation. In
this figure, you can see the breakthrough curves for a contaminant
along a 1D flowpath from the source, at four different times. If
distance 'X' had been chosen at time 3, the calculator would
return a very low concentration (as seen by where the t_{3}
breakthrough meets the dotted line indicating point 'X'). If time
4 had been chosen, the concentration would be significantly higher
(as seen by where the t_{4} breakthrough meets the dotted
line).

A landfill is leaking
leachate with a chloride concentration of 725 mg/L, which enters
an aquifer with the following properties:

Hydraulic conductivity =
3.0 x 10^{-3} cm/s

dh/dl (hydraulic gradient)
= 0.0020

Effective porosity = 0.23

Dispersion = 2.4 x 10^{-7}
m^{2}/s

Compute the concentration
of chloride in 1 y at a distance 15m from the point where the
leachate entered the groundwater. Chloride has a
retardation factor of 1.0.