Appendix A Glossary (Cont.)

Mixing The dilution or mingling of a discharge of water within receiving

waters. Mixing is used specifically in this document to describe dilution of

effluent or runoff discharges in surface waters.

Mixing zone A limited volume of water serving as a zone of initial dilution in

the immediate vicinity of the discharge point where receiving water quality may

not meet quality standards or other requirements otherwise applicable to the

receiving water. The mixing zone should be considered as a place where wastes

and water mix and not as a place where wastes are treated.

Nearshore Adjacent to a shoreline.

NEPA National Environmental Policy Act (40 CFR 1500-1508)

Pathway A route by which contaminants may leave a CDF.

Polluted dredged material Dredged materials that have been demonstrated to

impair the designated use of a water body.

Receptors of concern Humans, organisms, or other resources that have the

potential to be affected by contaminants of concern (COC) under the project-

specific conditions.

Reference Sediment or Soil A soil or sediment that reflects environmental

conditions that would have existed in the vicinity of a CDF if dredged material

had never been placed there, but all the other influences on environmental

quality at the site had occurred.

Risk assessment A procedure for evaluating and managing risk.

Runoff The liquid fraction of dredged material or the surface flow caused by

precipitation on upland or nearshore dredged material disposal sites.

Screen A procedure that has been demonstrated to have (1) some operational

advantage such as ease of conduct, low cost, short completion time, etc. and (2) a

low incidence of false indications of no environmental effect (low false

negatives), although it may have a higher incidence of false indications of

potential environmental effect (false positives). As a result of the second

characteristic, screening procedures can identify projects with little potential for

effects and projects for which more information is needed to make a decision,

but cannot identify projects that have a potential for effects.

Sediment Material, such as sand, silt, or clay, suspended in or settled on the

bottom of a water body. Sediment input to a body of water comes from natural

sources, such as erosion of soils and weathering of rock, or as the result of

anthropogenic activities, such as forest or agricultural practices, or construction

activities. The term dredged material refers to material, which has been dredged

from a water body, while the term sediment refers to material in a water body

prior to the dredging process.

Appendix A Glossary