Particulate Transport

Framework for Dredged Material Management

May 2004

Effects associated with volatilization of contaminants are evaluated based on

estimated exposure to selected receptors, and appropriate inhalation reference doses

(Myers, Schroeder and Estes in preparation (b)). Risk assessment may also be employed

in assessing the effects associated with exposure (Cura, Wickwire, and McArlde in

preparation).

5.3.9 Particulate Transport

Airborne transport of particulates from the surface of a CDF is also potentially of

concern. Exposure to contaminants may occur through inhalation of fine particles or

from direct contact with or ingestion of particles re-deposited in areas off-site. Tools to

quantify particulate transport are not well developed. Qualitative analysis of expected

surface conditions may identify periods when particulate transport will be of concern;

primarily when the material surface is dry, net precipitation is low, and prevailing winds

are sufficient to effect transport. Vegetation or surface covers may provide effective

control of particulate transport, although implementation may be logistically difficult due

to the size of the areas involved and the limited weight bearing capacity of the material

while it is still consolidating.

5.3.10 Need for Contaminant Controls

If the analysis of contaminant pathways and associated testing indicates that the

standards or Guidelines, as appropriate, are met, the CDF alternative is environmentally

acceptable from the standpoint of contaminant effects for that pathway. If the applicable

standards or Guidelines are not met, contaminant control measures can be considered to

reduce impacts to acceptable levels.

Control measures to minimize contaminant impacts may include operational

modification, treatment, site controls (e.g., liners or covers), and other site management

actions. These control measures are described in paragraph 5.4. If the control measures

are determined to be effective, then the alternative is environmentally acceptable from the

standpoint of contaminants. If there are no effective control measures for one or more

pathways, then disposal at the CDF under consideration should be eliminated.

5.4 Evaluation of Management Actions and Contaminant Control Measures

for CDFs

In cases where evaluations of direct physical impacts, site capacity, or

contaminant pathways indicate impacts will be unacceptable when conventional CDF

disposal techniques are used, management actions and contaminant control measures may

be considered. It should be noted that a CDF is neither a conventional wastewater

treatment facility nor a conventional solids-handling facility. The dredged materials

placed in CDFs typically contain 10 to 50 percent solids; therefore, an effective CDF

must incorporate features of both wastewater treatment and solids-handling facilities in a

combination that is unlike either (Averett et al. 1990).