During the Site Characterization phase of an RI/FS, a baseline risk assessment (RA) is used to evaluate the potential threat to human health and the environment in the absence of any remedial action. That is, the baseline RA describes the risk conditions under the "no action alternative." The baseline RA is extremely important because it provides the basis for determining whether remedial action is necessary. It also determines the extent of cleanup needed to reduce potential risk levels to within EPA's acceptable range carcinogenic risks of 10-4 to 10-6 - 40 CFR 300.430(e)(2)(i) (A)(2).