Preliminary Ranking and Recommendations

Preliminary Ranking and

Recommendations

Table 4 lists the preliminary ranking scores for uncertainty sources in the

tiered evaluation of dredged material. These scores should be viewed as initial

estimates of the relative amount of uncertainty associated with each source.

Scores ranged from 1 to 6. A source of uncertainty considered in the tiered

evaluation process and ranked low in magnitude received a score of 1. A source

of uncertainty for which the tiered evaluation process offers no explicit guidance

and which is ranked high in magnitude received a score of 6. A relatively small

subset of sources received a score of 3 or higher, and these sources are described

in the following paragraphs. Efforts to describe and reduce uncertainty in

dredged material disposal decisions should begin with these sources. Sources that

were not ranked (NR), classified as model-specific (MS), or classified as project-

specific (PS) were not scored, although they might be important. It is beyond the

scope of this report to quantify their importance. The following sections describe

sources of uncertainty, scored or unscored, that are good candidates for further

analysis.

COC Characterization

Identification of COCs received a score of 3 because some COCs might not be

evaluated at all in the tiered process. For example, contaminants that may have

potential endocrine-disrupting effects are not considered explicitly in USACE

guidance, although potential COC lists include some of these compounds.

Selection of Reference Sediment

Selection of reference sediments was not scored because, while applicable

USACE guidance is appropriate and thorough, uncertainty associated with poor

application of this guidance could not be quantified. However, it is clear that this

source of uncertainty deserves attention because the selection of reference

sediments is central to decisions made at every tier.

Chapter 6 Preliminary Ranking and Recommendations