Begin by reading Chapter 1, Fetter. This chapter contains background information which provides a perspective on groundwater as a resource together with a comprehensive overview of natural and man-made substances which cause deterioration of ground water quality. Pay particular attention to Table 1.2 (Substances known to occur in groundwater), Table 1.5 (USEPA drinking water standards and health goals), and Table 1.6 (Risk of getting cancer relative to drinking chlorinated tap water). Figure 1.1 (Fetter) identifies various mechanisms for ground water contamination. Figure I-1 below provides a similar overview. Note that Figure I-1 describes the behavior of both Light-Non-aqueous-Phase-Liquids (LNAPLS) and Dense-Non-Aqueous-Phase-Liquids (DNAPLS). NAPLS are immiscible with water and therefore retain a separate liquid phase. LNAPLS, such a gasoline, are less dense than water and therefore float on the surface of the water table, while DNAPLS have a density greater than water and thus sink below the water table. Chlorinated solvents are an example of DNAPLS. The properties and behavior of both types of NAPLS are of fundamental importance throughout this course.

Also please study Figure I-2 below. This figure identifies two very important concepts which relate to every other topic we will cover in the course. The first concept is called "scales of observation". Notice that processes such as biotransformation of organic contaminants occur at the Microscale or "Pore" scale. Notice also that bulk porous media properties such as permeability and porosity are not defined at the pore scale but acquire meaning at the larger scales of observation. Finally, at the field scale, porous media heterogeneities become significant and dominate flow and transport processes. At a larger scale regional flow system characteristics become significant.