Site Selection Considerations for Capping

Site Selection

Considerations

for Capping

General Considerations for Site Selection

The selection of an appropriate site is a critical requirement for any cap-

ping operation. Since the cap must provide long-term isolation of the con-

taminated material, capping sites should generally be characterized as

nondispersive sites, where material is intended to remain in a stable de-

posit. Therefore, the considerations for site selection for a conventional

nondispersive open-water disposal site also apply to capping sites

(Palermo 1991b).

Sites in ocean waters are regulated by MPRSA. For MPRSA sites, a

formal site designation procedure includes a detailed evaluation of site

characteristics. Sites in inland and near-coastal waters (inland of the base-

line of the territorial sea) are regulated by CWA. The specification of dis-

posal sites under the CWA is addressed specifically in the Section 404

(b)(1) guidelines. Any capping project in waters of the United States must

occur at a specified 404 site.

A number of site characteristics must be considered in designating or

specifying an open-water disposal site. These characteristics include the

following:

Currents and wave climate.

Water depth (including consideration of navigable depth).

Bathymetry (particularly slopes).

Potential changes in circulation or erosion patterns related to refrac-

tion of waves around the disposal mound.

Groundwater flow (consideration for some nearshore sites).

Bottom sediment physical characteristics, including sediment grain-

size differences.

Chapter 4 Site Selection Considerations for Capping