2.2 Considerations for Risk Assessment

control surface runoff will also control plant or animal bioaccumulation.

Consideration of such influences may allow for a reduction in testing efforts or the

need to reevaluate some pathways. The full evaluation of all pathways may

therefore be an iterative process, depending on the project requirements.

2.2 Considerations for Risk Assessment

This section discusses the similarities between risk assessment and the general

UTM evaluation process within any tier of each pathway. As discussed in Section

2.1, the tiered process is intended to provide a decision in most cases without

having to conduct a formal, quantitative risk assessment in Tier IV. However,

even while intending to avoid Tier IV, it is important to recognize that some

aspects of the project evaluation may require a Tier IV risk assessment. The

evaluations in Tiers I through III provide the data for risk assessment, should it be

needed.

2.2.1 Overview of Risk Assessment

Risk assessment as it has often been used in other applications has typically

been thought of as a complex, time-consuming, and expensive process. However,

the concept of "screening level" risk assessments is being more widely embraced,

and risk assessment concepts are being applied in simpler, quicker, and more

efficient forms. The UTM is consistent with this trend, with its integration of risk

assessment elements into a tiered testing framework culminating in a formal,

quantitative risk assessment in the ultimate tier.

The fundamentals of the risk assessment process and its application to

dredged material evaluation are discussed in Moore, Bridges, and Cura (1998).

This overview of the risk assessment process is supplemented by Cura et al.

(2001), which discusses risk assessment as it applies to aquatic disposal of

dredged material, and Cura, Wickwire, and McArlde (in preparation), which

discusses risk assessment in the management of dredged material in wetland and

terrestrial habitats. The brief summary of risk assessment in this section merely

provides a context for discussing the risk elements of the UTM evaluation

process. The much more thorough discussion by Cura, Wickwire, and McArlde

(in preparation) is an important companion to the UTM, and the user should be

familiar with it to make the best use of the UTM in the context of risk assessment.

If it is necessary to carry the evaluation in the UTM to Tier IV, the guidance on

Tier IV risk assessments provided by Cura, Wickwire, and McArlde (in

preparation) should be followed.

At a fundamental level, risk assessment consists of the following four steps,

illustrated in Figure 2-2.

Problem formulation involves a thorough description of the activity

being evaluated, with an emphasis on the COC (Section 2.2.2), ROC

(Section 2.2.3), and complete exposure route(s) by which ROC could

plausibly come into direct physiological contact with COC under the

2-7

Chapter 2 Structure and Approach of the UTM