2.2.2 Contaminants of Concern

2.2.2 Contaminants of Concern

COC are the constituents or contaminants present in the dredged material

being evaluated that may have a potential to affect ROC. General COC concepts

are presented here, and COC are discussed in relation to Tier I evaluations in

Section 3.4 and in detail specific to each pathway in Chapters 4 through 9.

The COC are likely to be different for each dredged material and for a

particular dredged material, are likely to be different for different pathways. COC

to be evaluated are identified on a case-specific basis in the Tier I evaluation for

each pathway. If little information is available, the evaluation may enter Tier I

with a "standard laundry list" of potential COC. However, through the Tier I

process the "standard laundry list" should be replaced by a set of potential COC

specific to the dredged material and pathway being investigated. It is important

that all constituents relevant to the disposal activity being evaluated are included

as potential COC. Constituents that Tier I shows may be important to a particular

investigation should be added, and constituents that Tier I provides no reason to

believe may be relevant to a particular investigation should be deleted from the

potential COC. While there may be some constituents that are truly of concern

and are legitimately among the COC for most investigations, detailed

investigation of constituents not relevant to the disposal activity being evaluated

are of no benefit and should be avoided.

2.2.3 Receptors of Concern

ROC are the resources that may have a potential to be affected by COC. ROC

include abiotic resources such as water quality, groundwater quality, and air

quality as well as the more commonly thought of biotic resources such as

particular plant or animal species. ROC may be different for each CDF, and for a

given CDF, are likely to be different for different pathways.

ROC are mentioned here because ROC is a term common to both the UTM

and risk assessment. Because ROC are the resources potentially at risk, the ROC

determine the tests that will be conducted. In some cases, ROC are evaluated

directly, such as when water quality is evaluated by measuring COC

concentrations and comparing these to standards. In other cases, ROC may not be

amenable to direct evaluation. For example, the resource of concern may be a

local population of edible fish. It is often not possible to directly evaluate potential

effects on the population, and it may not even be possible or practical to test

individual fish of the species of interest. Such cases are common and are

addressed with tests of surrogate species from which effects on the population of

interest are inferred. The selection of appropriate test species is discussed in the

sections of Chapters 4 through 9 in evaluations that use biological effects tests.

2.2.4 Basis of Management Action Decisions

The purpose of management actions is to protect ROC outside the CDF. As

noted above, ROC may be abiotic, such as water quality standards, or biotic, such

as particular organisms. The decision that management actions are required to

2-10

Chapter 2 Structure and Approach of the UTM