Definition: Utilizing dredged sediments as resource materials in productive ways which provide environmental, economic, or social benefit.
Introduction: Several hundred million cubic yards of sediment must be dredged from United States ports, harbors, and waterways each year to maintain and improve the nation's navigation system for commercial, national defense, and recreational purposes. Traditional dredging methods discharge sediment into confined disposal facilities or waters of oceans, rivers, lakes, wetlands, and estuaries. Dredged material containment facilities in the United States are nearly or are already filled to capacity with material. Identifying new containment sites poses difficulties due to conflicting land uses, potential environmental impacts, and high values of near-water real estate.
Due to growing scientific knowledge and public awareness of using dredged material as a valuable resource, beneficial use of dredged material has become a viable alternative to traditional "dredge and dispose" methods for many projects. Prior to 1970, beneficial uses of dredged material typically included creating or expanding land for airports, ports, residential, or commercial development. Environmental, economic, social, and other benefits can be derived from the productive use of dredged material. Dredged material is increasingly used beneficially for a greater variety of projects and purposes.
Beneficial uses of dredged material have been classified, for the purpose of these discussions, into seven categories:
- Habitat Development
- Shore Protection
- Parks and Recreation
- Reclamation and Remediation
- Construction and Industrial
- Agriculture, Forestry, Horticulture, and Aquaculture
- Emergency Response Actions
Often, dredged material placements can yield multiple beneficial uses. For example, beach nourishment activities may simultaneously provide shore protection and recreational opportunities.
The composition and grain size distribution of dredged material is important in matching the material with the intended beneficial use. For simplification, dredged material is characterized as one of five sediment types: rock; gravel and sand; consolidated clay; silt/soft clay; and mixture (rock/sand/silt/soft clay). Numerous other factors must be evaluated when considering beneficial use options for dredged materials such as: contaminant status of materials; site selection; technical feasibility; environmental acceptability; cost/benefit; and legal constraints.
The placement and disposal of dredged material is managed and conducted by Federal, state, and local governments: private entities; and semi-private entities, such as port authorities. The U.S. Army Corps of Engineers issues permits for the disposal of dredged material, while the role of the U.S. Environmental Protection Agency is to provide oversight and/or authorization, as applicable, for the placement of dredged materials.
Beneficial uses of dredged material may make traditional disposal of dredged material unnecessary or at least reduce the frequency of disposal. However, monitoring of the dredged material placement sites is critical for measuring success. Focused identification of opportunities and continued development of applications to utilize dredged material for beneficial uses are necessary.