Environmental and Human Risk Characterization

The decision about whether the conditions at a contaminated site are serious enough to require remediation necessitates an evaluation of the contaminant properties and the effects on humans and the environment, the uses of impacted properties, and the accessibility of the contamination. Risk characterization incorporates these factors into a process that evaluates risks associated with site contamination and whether the risks are sufficient to require a response action. The outcome of a risk characterization either: 1) determines the generic regulatory cleanup levels (i.e., soil or ground water concentrations) that are applicable to the site; or 2) produces combinations of contaminant cleanup levels that will result in an acceptable risk to humans and the environment. 

Risk characterization studies performed by GeoInsight typically fall into three categories:

Baseline risk characterization evaluates the risk that would exist in the absence of remediation over a long period of time. At many sites, a baseline risk characterization is not necessary where it is obvious that remediation is necessary. This approach allows resources to be spent on cleaning up the contamination instead of evaluating the risk. At other sites where contamination is not as significant, the baseline risk characterization may be used to demonstrate that remediation is not necessary or that previous remediation was adequate.

Imminent hazard evaluations are risk characterizations that are performed to evaluate if remediation requirements are immediate. It is a form of baseline risk characterization that evaluates risk over a short duration. Imminent hazard evaluations are not required at all sites, but are triggered by the presence of conditions indicating the potential for risk in the short term.

Identification of cleanup levels is necessary when it is obvious that remediation is required or the baseline risk characterization indicates there are unacceptable risks at a site. GeoInsight applies risk characterization to define when remediation can be terminated. The use of risk characterization under these scenarios prevents unwarranted or excessive remediation, thus controlling costs.