Contaminant Status of Materials
Evaluating the contaminant status of the dredged material is the first step to determine if the material is acceptable for beneficial use. Contaminant issues will not be addressed in any detail here but must be considered in every decision process for beneficial uses. In general, highly contaminated sediments will not normally be suitable for most proposed beneficial use applications and particularly for proposed wildlife habitat development projects. However, after appropriate examination, testing, and treatment, the material may be classified as suitable. Dredged material from ongoing activities (maintenance dredging) should be reevaluated periodically to ensure that the sediment contamination level has not worsened since the last dredging cycle. Guidance for evaluating the contaminant status of dredged material can be obtained from local, state, or national regulatory agencies and key references listed.
Selecting a placement site and choosing a beneficial use are interdependent decision processes. Dredged material may have multiple beneficial use options and there may be serveral different potential placement sites. Often, the characteristics of the sediments determine or limit the types of sites that may be selected and the beneficial uses that can be achieved. Once a potential use and site have been identified various implications should be assessed such as technical feasibility, environmental acceptability, cost/benefits, and legal constraints.
The technical feasibility of implementing a particular beneficial use at a designated site must be evaluated. Various constraints must be considered, such as pumping distance, water depth, access, etc. If technical feasibility constraints will not allow the proposed beneficial use and/or selected site, then alternate beneficial use or disposal options must be pursued.
Before any substantial work can be undertaken, the environmental impact prior, during, and subsequent to construction of the proposed project must be investigated. An Environmental Impact Assessment (EIA) should be performed on all projects. Major projects will also require an Environmental Impact Statement (EIS). An EIA is generally a qualitative evaluation document of potential environmental impacts, whereas an EIS is more rigorous and quantitative, based on significant sampling and testing. The chosen beneficial use options may be pursued if it is concluded that the environmental effects will not be significantly harmful. Permission to undertake or permit the dredged material placement may be denied if the proposed work is likely to have any significant adverse environmental effects.
After one or more potential beneficial use options have been identified and the engineering methods have been defined, estimated costs and benefits should be analyzed. The costs are usually estimated by standard methods. Options for beneficial use may lower the cost for disposal of dredged material in many instances, but increase costs in other scenarios. Costs are frequently lower when distances from dredging site to disposal site are reduced. In cases with higher costs, the increase may be more than offset by the value of the benefits. Although difficult to quantify, intangible benefits should always be taken into account when assessing overall costs and benefits. These benefits may include improved habitat, esthetic enhancement, a more viable local community, and other benefits.
Early and concentrated coordination between permitting agencies, local interests, and environmental protection agencies is mandatory. Some beneficial use options or sites selected may be prohibited or rendered inappropriate by law or regulation. However, some beneficial uses may actually be encouraged through grants or subsidies by governmental or private organizations. Guidance for legal policy and regulations can be obtained from local, state, or national regulatory agencies. Some references and links regarding the laws and regulations applicable to the beneficial use of dredged materials are available from this site.