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Policy Statement 349 - Dredged Management for Erosion Control, Channel Maintenance and Coastal Protection

 
Approved by the Energy, Environment and Water Policy Committee on March 13, 2020
Approved by the Public Policy Committee on May 18, 2020
Adopted by the Board of Direction on July 11, 2020

Policy

The American Society of Civil Engineers (ASCE) supports the beneficial management of dredged sediments and dredged material.  ASCE recommends that:

  • The federal government revise its methodology for economic analysis of dredging costs to reflect the benefits of using dredged material for coastal protection, environmental stewardship and other beneficial uses.
  • Government and private entities with projects which require dredging should provide for regional sediment management that identifies coordinating agencies and their sediment needs with dredging frequencies, locations and quantities in order to beneficially utilize as much dredged material as practical.
  • Contaminated sediments, considering the contaminant and degree of contamination, be evaluated for selected beneficial uses.
  • Dredged materials be considered for use in coastal areas that are vulnerable to erosion or sediment deposit that cause environmental degradation or endanger recreational, economic, or commercial activities.
  • Innovative technology and new ideas be allowed for testing in robust pilot study programs.

Issue

The growing scientific knowledge and public awareness of using dredged material as a valuable resource, has made the beneficial use of dredged material 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. With modern applications, 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. Pilot projects, such as those authorized under Section 1130 or the Water Resources Development Act (WRDA) of 2018, are key to moving ahead with implementation of beneficial use of dredge material. 

Often there is little coordination between government agencies concerned with maintaining safe navigation channels through coastal inlets and those agencies and local jurisdictions concerned with beach erosion. The economic feasibility of navigation channel maintenance and beach erosion control projects are usually assessed independently of each other. Thus, minimizing the cost of an inlet navigation project often dictates that sand dredged from the inlet be disposed offshore. At the same time, nearby beaches may experience severe erosion because sand in transport along the shore is trapped by the inlet and removed from the beach and coastal systems. Beach-quality sediment and sand dredged from navigation projects and inlets should be placed wherever feasible and with appropriate planning, on beaches that most need nourishment to reduce the effects of erosion. Non-beach quality sediment and sand should be considered for use elsewhere, such as in thin layer wetland restoration or marsh creation, as appropriate.

Monitoring of dredged material placement sites is critical to the success of a project. Site requirements and the particular beneficial use must be considered in determining the most efficient and effective monitoring plan. A comprehensive monitoring plan should include properly selected monitoring tools and study design; pre-placement and post-placement data collection; and clearly defined success criteria. The sophistication of the monitoring program depends on the beneficial use and the environmental impact.

Rationale

Beneficial use of dredged material has been a topic of discussion for years but has not received the emphasis needed to change national dredging practice. As a nation, we need to implement the new federal policy on the beneficial use of dredged material as the standard practice for federally sponsored dredging projects. The beneficial use of dredged materials, when used for geotechnical engineering applications, channel maintenance, coastal protection, beach erosion control, and habitat creation makes both economic and environmental sense and constitutes a major part of comprehensive sediment management.

ASCE Policy Statement
First Approved in 1989




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