Overview and Description of the Capping Process

Convention, including its Annexes," to the extent this would not result in

relaxation of MPRSA requirements.

In evaluating proposed ocean placement activities, the USACE is re-

quired to apply criteria developed by the EPA relating to the effects of the

proposed placement activity. The MPRSA criteria are given in 40 CFR

220-227. In evaluating proposed placement activities in inland or coastal

waters, the USACE is required to apply guidelines given by Section 404

of the CWA to ensure that such proposed discharge will not result in unac-

ceptable adverse environmental impacts to waters of the United States.

The guidelines are given in 40 CFR 230. A tiered approach to sediment

testing and assessments is described in detail in the dredged material test-

ing manuals for MPRSA and CWA (EPA/USACE 1991; EPA/USACE

1998).

This report addresses technical and scientific issues associated with

capping and does not address the various regulatory requirements of the

CWA and MPRSA. Whether or not a particular project involving capping

satisfies the relevant regulatory criteria can only be determined by apply-

ing the relevant requirements of the regulation and consulting, as neces-

sary, with legal counsel.

Overview and Description of the Capping

Process

Capping defined

For purposes of this report, the term "contaminated" refers to material

for which isolation from the benthic environment is appropriate because

of potential contaminant effects, while the term "clean" refers to material

found to be acceptable for open-water placement. Capping is the controlled

accurate placement of contaminated material at an open-water placement

site, followed by a covering or cap of clean isolating material. For most

navigation dredging projects, capping alternatives involving armor stone

layers or other nonsediment materials for capping would not normally be

considered.

Level-bottom capping (LBC) is defined as the placement of a contami-

nated material in a mounded configuration and the subsequent covering of

the mound with clean sediment. Contained aquatic disposal (CAD) is

similar to LBC but with the additional provision of some form of lateral

confinement (e.g., placement in natural-bottom depressions, constructed

subaqueous pits, or behind subaqueous berms) to minimize spread of the

materials on the bottom. An illustration of LBC and CAD is shown in

Figure 1.

The objective of LBC is to place a discrete mound of contaminated ma-

terial on an existing flat or gently sloping natural bottom. A cap is then

applied over the mound by one of several techniques, but usually in a series

of placement sequences to ensure adequate coverage. CAD is generally used

Chapter 1 Introduction