Figure 1-3. Schematic of contaminant migration pathways for nearshore CDFs

Volatilization

Weir

Bioturbation

Effluent

Unsaturated

High Tide

Ground

Partially

Water

Infiltration

Saturated

Low Tide

Soluble Diffusion

Saturated

Seepage

Existing

Leachate

Seepage

Bottom

Figure 1-3. Schematic of contaminant migration pathways for nearshore CDFs

1.4 Applicability

1.4.1 Disposal in CDFs

The UTM provides methods for assessment, where appropriate, of potential

effects of proposed disposal of dredged material in upland, nearshore, and island

CDFs. It uses physical, chemical, and biological analyses as necessary to provide

effects-based conclusions within a tiered framework regarding potential

contaminant-related impacts outside the CDF associated with the five potential

pathways (USACE/EPA 1992): effluent, precipitation runoff, leachate and

seepage, volatilization, and direct uptake by wetland and terrestrial plants and

animals.

1.4.2 This Manual Does Not Address

Impacts at the dredging site associated with the dredging activity itself.

Physical impacts related to construction of the CDF and the disposal of

dredged material.

Impacts associated with material excavated from drainage ditches and

land clearing activities.

Impacts associated with the discharge of fill material.

Submerged confined disposal, such as CAD, disposal in CAD pits,

capping, or other disposal activities in the aquatic environment.

Any unconfined disposal (e.g., beach nourishment), whether on land, in

wetlands, nearshore, or in water.

Microbiological impacts unless there may be human health concerns.

1-5

Chapter 1

Introduction