(Editors Note -- the example problem presented in this chapter is a contrived system that cannot exist in reality. The input parameters, when considered individually, are reasonable; but when combined together, yield an impossible system: namely the dissolved TCE concentration is too high for bioremediation using the chosen kinetic biodegradation parameters, and the dispersitivity coefficient is too high for the aquifer size and groundwater velocity. However, this chapter still provides a good example of how to use the model, hence it is included. Please excuse the neglect in parameter selection.)

This chapter illustrates how to present physical systems in mathematical form for the numerical model. This process divides into three major steps: aquifer discretization and flow field boundary conditions; selection of mobile and immobile species; and identification of reaction processes.

This chapter will analyze one-dimensional flow and transport in a saturated confined aquifer contaminated with a TCE spill. Aquifer reactions will include TCE dissolution, sorption, and biodegradation by methanotrophs. The purpose of analyzing the hypothetical aquifer is to illustrate model capabilities. This chapter will not conduct a comprehensive analysis of the problem.