8.3.2 Tier II Theoretical Bioaccumulation Potential Decision

whether there is an indication of greater bioaccumulation from the dredged

material than from the reference.

8.3.2 Tier II Theoretical Bioaccumulation Potential Decision

After consideration of the Tier II animal bioaccumulation information in the

context of the conceptual site model and the complete exposure routes to ROC

populations outside the CDF, one of the following conclusions is reached for

nonpolar organic COC.

1. Information is sufficient to reach a decision regarding animal

bioaccumulation. This is the case where the TBP of the dredged material

is not statistically greater than the TBP of the reference material. No

further evaluation of animal bioaccumulation is necessary.

2. Information is not sufficient to reach a decision regarding animal

bioaccumulation. This is the case if the TBP of the dredged material is

statistically greater than the TBP of the reference material, or there are

COC other than nonpolar organics. Further evaluation in Tier III, or

management actions as an alternative to further evaluation, should be

considered. A decision to implement management actions for animal

bioaccumulation by interrupting complete exposure routes to ROC

outside the CDF may require more detailed information prior to design of

such actions. If management actions are selected, no further evaluation of

animal bioaccumulation is necessary.

8.4 Tier III Animal Bioaccumulation Test

The Tier III animal bioaccumulation test uses earthworms for the same reason as

the Tier II evaluation. The Tier III procedure determines the potential

bioaccumulation of COC under freshwater terrestrial conditions by earthworms, a

representative soil invertebrate known to accumulate a wide variety of

contaminants from the soil in which it lives. This test procedure has been

established as ASTM SE-1676 Standard Procedure (ASTM 1997) and is provided

in Appendix G. The procedure is applicable to all COC for animal

bioaccumulation, whatever their chemical nature. The bioaccumulation assay

provides information on (1) bioavailability and mobility of COC from soil to the

soil-dwelling earthworms, and (2) the potential for COC movement to higher

organisms (e.g., birds, mammals, amphibians, reptiles) from off the site linked to

worms in the food web.

8.4.1 Tier III Animal Uptake Test Procedure

The Tier III animal bioaccumulation procedure measures COC

bioaccumulation by earthworms from the dredged material and a reference

material. The test consists of a direct exposure of the earthworms in both dredged

material and reference. A photo of a typical test setup is shown in Figure 8-2.

8-12

Chapter 8

Animal Bioaccumulation