Chemical/biological characterization

and Unified Soil classification as well as geotechnical data should be

evaluated as necessary.

The characteristics of the capping sediment should be compatible with

the contaminated sediment, considering the placement technique for both.

Previous studies have shown that both fine-grained materials and sandy

materials can be effective capping materials.

Chemical/biological characterization

The capping sediment must be one that is acceptable for unrestricted

open-water placement (that is a clean sediment). Further, the capping sedi-

ment must be acceptable for open-water placement from the standpoint of

both potential water column and potential benthic effects. In order to

make such a determination, some chemical and biological characterization

of the contaminated sediment is normally performed as a part of the over-

all evaluation for suitability for open-water placement (EPA/USACE 1991;

EPA/USACE 1998).

Sampling and Testing Plans

Samples of sediments must be obtained for physical, chemical, or

biological characterization as described above. Samples may also be re-

quired for other engineering or environmental testing such as the capping

thickness testing described in Chapter 7 and Appendix C.

General guidance on design of sampling plans is available (EPA/USACE

1991; EPA/USACE 1998), but most sampling plans will be site specific.

The full range of anticipated testing must be considered in developing

sampling plans. Appropriate sampling equipment, sampling techniques,

and sample preservation procedures should be used.

Variability can be exhibited in vertical as well as horizontal location of

specific samples. Sampling should define material to the total depth of

dredging. Grab samplers or box corers are generally appropriate for shallow

thickness of sediment, while core samples (by vibracore or conventional

coring equipment) are normally required for thicker sediment deposits or

deposits in which stratification must be defined. Detailed guidance on

sampling equipment and procedures is available (Mudrock and McKnight

1991.)

Testing of samples from specific locations is usually done for charac-

terization purposes. Compositing should be considered for some engineer-

ing or environmental testing (e.g., consolidation tests, elutriate tests,

bioassays, capping effectiveness tests). Administrative agreement be-

tween all concerned regulatory agencies regarding the acceptability of the

sampling and testing plan should be obtained prior to sampling and testing.

Chapter 3 Characterization of Contaminated and Capping Sediments