ABSTRACT
The groundwater monitoring example discussed in Chapter 1 involves comparing chemical concentrations at the downgradient wells with “background” values based on upgradient wells (for detection monitoring) or comparing them with Ground Water Protection Standards (for assessment monitoring). The soil cleanup example discussed in Chapter 1 involves comparing chemical concentrations in soil with a “soil screening level.” Any activity that requires comparing new values to “background” or “standard” values creates a decision problem: If the new values greatly exceed the background or standard value, is this evidence of a true difference (i.e., is there contamination)? Or are the true underlying concentrations the same as background or the standard value and this is just a “chance” event? Table 6.1 illustrates this decision problem (see Tables 2.1 and 2.2 in Chapter 2).
