Design/Management Sequence for Capping

Design/Management

Sequence for Capping

Design Philosophy for Capping

Capping is not a form of unrestricted open-water placement. A cap-

ping operation is an engineered project with carefully considered design,

construction, monitoring, and maintenance to ensure that the design is ade-

quate. A successful capping project requires a team approach with input

from engineers, biologists/ecologists, chemists, and dredging operations

experts. The basic criterion for a successful capping operation is that the

cap thickness required to isolate the contaminated material from the envi-

ronment be successfully placed and maintained.

Dredged Material Capping Functions

A dredged material cap can serve three primary functions:

a. Physical isolation of the contaminated dredged material from the

benthic environment.

b. Stabilization of contaminated material, preventing resuspension and

transport to other sites.

c. Reduction of the flux of dissolved contaminants into the cap and

overlying water column.

If a dredged material is unsuitable for open-water placement due to po-

tential contaminant impacts, physical isolation of the dredged material

from the benthic environment and from resuspension and transport offsite

would normally be primary functions of a dredged material cap. Control

of contaminant flux may be a desired function, depending on the sediment

characteristics, site conditions, and other factors.

Chapter 2 Design/Management Sequence for Capping