8.1.4 Summary of Tiered Evaluation of Animal Bioaccumulation

acceptable level of animal bioaccumulation. Although statistical significance, per

se, cannot indicate environmental importance, a statistically significant increase

above reference bioaccumulation has been considered in the OTM and ITM to

indicate a potential for effects, and that convention is followed in the Tier II and

III animal bioaccumulation in the UTM. Detailed decision guidance is provided

in the discussions of each of the tiers.

8.1.3 Data Requirements

The evaluation of animal bioaccumulation requires information on the CDF

and its environmental setting, the planned dredged material management, and the

characteristics of the dredged material. Much of this comes from the available

information compiled in Tier I, and supplemented (if necessary) by the Tier II and

Tier III test data.

8.1.4 Summary of Tiered Evaluation of Animal Bioaccumulation

A flowchart illustrating the tiered evaluation for animal uptake is shown in

Figure 8-1. The other contaminant mobility pathways addressed in the UTM are

evaluated primarily on the basis of standards or criteria, and risk assessment plays

a relatively minor role in Tiers I through III. In the absence of technically

applicable standards or criteria, animal (and plant) bioaccumulation evaluations in

the UTM rely more directly on risk assessment in Tiers I through III. Evaluation

of all pathways relies on risk assessment in Tier IV.

The risk-based approach to evaluation of animal bioaccumulation is structured

around the conceptual site model developed in Tier I. The conceptual site model

provides the framework and the context for conducting the evaluation (Cura,

Wickwire, and McArlde in preparation). It describes the dredged material

management planned, the environmental setting of the site, and how the planned

site management interacts with the environmental setting to determine what

effects might potentially occur. The evaluation in Tiers I through III emphasizes

three components evaluated in the context of the conceptual site model:

Populations of receptors of concern (ROC) outside the CDF, discussed in

Section 2.2.3

Constituents of concern (COC), discussed in Sections 2.2.2 and 3.4

Complete exposure routes, discussed in Section 2.2.4. Identification of

reasonable complete exposure routes by which ROC populations outside

the CDF can come into direct physiological contact with COC is key to

the entire evaluation. If there are no reasonable complete exposure

routes, there can be no exposure and thus no effect or risk.

8-3

Chapter 8

Animal Bioaccumulation