Direct Physical Impacts

Framework for Dredged Material Management

May 2004

Topography to include potential changes in elevation and runoff patterns and

adjacent drainage.

Ability of the dredged material to eventually dry and oxidize.

Groundwater levels, flow and direction, and potential impact on groundwater

discharge and recharge.

Meteorology and climate.

Foundation soil properties and stratigraphy.

Potential groundwater receptors.

Potential alteration of the existing habitat type.

Potential for effluent, leachate, and surface runoff impacting adjacent ground

and surface water resources.

Potential for direct uptake and movement of contaminants into food webs.

Potential for volatilization of contaminants.

Potential for dust, noise, or odor problems.

Potential to implement management activities when deemed necessary.

Potential accessibility of the site by the public.

Contamination history of proposed site.

Field exploration programs are necessary to assess many of the above

considerations in determining the suitability of a site for use as a CDF. Foundation

explorations are especially important for dike design and groundwater assessments.

Additional information regarding sampling techniques and equipment and development

of field exploration programs for CDFs is given in EM 1110-2-5027 (USACE 1987).

5.2 Evaluation of Direct Physical Impacts and Site Capacity

An evaluation of direct physical impacts and initial and long-term CDF site

capacity should precede any evaluations of contaminant impacts, since elimination of

alternatives based on unacceptable physical impacts or inadequate site capacity could

reduce the need for more expensive and involved testing for contaminant effects.

5.2.1 Direct Physical Impacts

Direct physical impacts because of construction of the CDF must be assessed.

Such impacts may include alteration of habitat, changes in hydrological conditions (e.g.,

circulation patterns in surface waters and groundwater recharge), restrictions to

navigation, and aesthetic, cultural, and land-use impacts. Guidance on evaluation of such

physical impacts in waters of the United States is available (40 CFR 230).

5.2.2 Initial Storage Capacity and Solids Retention

A CDF must be designed and operated to provide adequate initial storage volume

and surface area to hold the dredged material solids during an active filling operation and

if hydraulically filled, to retain suspended solids such that clarified water is discharged.

The required initial storage capacity and surface area is governed by zone, flocculent, and

compression-settling processes which occur in a CDF during placement of fine-grained