3.4.3 Documentation of COC

easily take them up, and, once in the body, they cannot be readily

broken down and eliminated.

Stereochemistry - The spatial configuration (i.e., stereochemistry) of

a neutral molecule affects its tendency to bioaccumulate. Molecules

that are planar tend to be more lipid- soluble (lipophilic) than do

globular molecules of similar molecular weight. For neutral organic

molecules, planarity can correlate with higher bioaccumulation unless

organisms can easily metabolize the molecule.

3.4.3 Documentation of COC

Justification for identifying a contaminant as a COC increases with the

increase of factors such as the:

Toxicological importance of the contaminant.

Amount of the contaminant known to have been introduced to the

dredging site.

Amount of the contaminant suspected to have been introduced to the

dredging site.

Amount of the contaminant included in continuing input from existing

sources.

Amount of the contaminant included in historical sources.

Justification for identifying a contaminant as a COC decreases with the

increase of factors such as:

Isolation of the dredging operation from known existing and historical

sources of the contaminant.

Time since historical sources of contaminant have been remediated.

Number and frequency of maintenance dredging operations since

abatement of the source of the contaminant.

Mixing and dilution occurring between the contaminant source and the

dredging site.

Transport and potential deposition of sediment in the dredging area from

sources other than those potentially affected by the contaminant.

Grain size of the dredged material.

These and other considerations are complexly interrelated; i.e., the acceptable

degree of isolation from sources of contaminants depends on the number, amount,

and toxicological importance of the contaminants as well as on all other factors.

3-11

Chapter 3

Initial Evaluations