Characterization of Contaminated and Capping Sediments

Characterization of

Contaminated and

Capping Sediments

Need for Sediment Characterization

Characterization of both the contaminated sediment and potential cap-

ping sediments is necessary for evaluation of the environmental accept-

ability of sediments for open-water placement and to determine physical

and engineering properties necessary for prediction of both short- and

long-term behavior of the sediments. Some characterization data may

have been obtained as a part of a more general investigation of disposal

alternatives prior to consideration of capping.

Characterization of Contaminated Sediment

The contaminated sediments to be capped are likely to have been char-

acterized to some degree prior to consideration of capping. In any event,

the contaminated sediment must be characterized from a physical, chemi-

cal, and biological standpoint.

Physical characterization

The physical characteristics of the contaminated sediment are of impor-

tance in predicting the behavior of the material during and following place-

ment at a capping site. Physical characterization is needed for evaluations

of dispersion and spread during placement, mounding characteristics, and

long-term stability and resistance to erosion.

Physical tests and evaluations on sediment should include visual classi-

fication, natural (in situ) water content/solids concentration/bulk density,

plasticity indices (Atterberg limits), organic content, grain-size distribution,

specific gravity, and Unified Soil classification. Standard geotechnical

laboratory test procedures, such as those of the American Society for Test-

ing and Materials (ASTM), the American Association of State Highway

Chapter 3 Characterization of Contaminated and Capping Sediments