Relative Risk Site Evaluation

The relative risk site evaluation is a methodology used by all DoD Components to evaluate the relative risk posed by a site in relation to other sites. It is a tool used across all of DoD to group sites into high, medium, and low categories based on an evaluation of site information using three factors: the contaminant hazard factor (CHF), the migration pathway factor (MPF), and receptor factor (RF). Factors are based on a quantitative evaluation of CERCLA hazardous substances, pollutants, or contaminants and a qualitative evaluation of pathways and human and ecological receptors in the four media most likely to result in significant exposure – ground water, surface water, sediment, and surface soils. A representation of this evaluation concept is presented in Figure 11-1 (below).

The relative risk site evaluation framework is a qualitative and easy to understand methodology for evaluating the relative risks posed by sites and should not be equated with more formal risk assessments conducted to assess baseline risks posed by sites. It is a tool to assist in sequencing environmental restoration work (i.e., known requirements such as remedial investigation or cleanup actions) to be done by a DoD component. It is designed to handle the broad range of sites that exist at DoD installations and the broad range of data available. Like any risk evaluation tool and perhaps more so than a comprehensive risk assessment, the relative risk site evaluation framework makes use of assumptions and approximations. Users should bear these limitations in mind when applying the framework. Relative risk is not the sole factor in determining the sequence of environmental restoration work, but it is an important consideration in the priority setting process. It should be factored into all priority setting decisions and discussed with regulators and public stakeholders in the environmental restoration process. The grouping of sites into high, medium, or low relative risk categories is not a substitute for either a baseline risk assessment or health assessment; it is not a means of placing sites into a Response Complete/No Further Action category; and it is not a tool for justifying a particular type of action (e.g., the selection of a remedy).

The relative risk site evaluation framework is used by all DoD Components to assess site relative risks at installations and formerly used defense properties. Use of the framework and resulting relative risk information allows DoD and DoD Components to communicate and help establish priorities for environmental restoration work.

The actual funding priority for a site is identified after relative risk information is combined with other important risk management considerations (e.g., the statutory and regulatory status of a particular installation or site, public stakeholder concerns, program execution considerations, and economic factors). These additional risk management considerations can result in a decision to fund work at a site that is not classified as a high relative risk. DoD Components have each developed guidelines for combining relative risk and risk management considerations as past of their planning, programming, and budgeting process with DoD. The relative risk site evaluation framework does not address the question of whether work is necessary at a site; it only provides information for use in helping to determine the general sequence in which sites will be addressed. At the DoD headquarters level, it also provides a framework for planning, programming, and budgeting requirements.

Use of the relative risk site evaluation framework is restricted to environmental restoration sites and does not extend to unexploded ordnance (UXO) removal, building demolition/debris removal (BD/DR), potential responsible party (PRP) activities, or compliance activities.

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