Environmental Risk Assessment of Dredging and Disposal Operations


2006 | softcover | 40 pp. | PIANC | ISBN: 2-87223-160-9

Various risk-based methods are used to assess environmental impacts from dredging and dredged material management activities.

PIANC Work Group 10 developed guidance for conducting risk assessments at dredged material management sites to help environmental scientists and engineers apply such techniques to the decision-making process. It explicitly recognizes that risk assessment alone cannot fully inform the process, nor does it necessarily apply to all sites.

The application of risk assessment probably applies most profitably where screening level assessments or familiar regulatory procedures are unable to parse among technologies or sites. Risk assessment is a deliberate and transparent analytical framework that incorporates site-specific physical, chemical, and biological characteristics into an estimate of risk of potential environmental harm. It avoids the pitfalls common to the application of generic standards or criteria that are generally:

  • Blind to the potential mitigating influence of site-specific conditions;
  • Fixed, and unable to incorporate recent scientific advances into immediate applications;
  • Often developed as protective of a most sensitive”” species
  • Insensitive to any expression of uncertainty that may be valuable to the decision maker
  • Limited to a small subset of compounds.

The guidance identifies the incorporation of risk assessment or risk estimation in many existing national sediment evaluation procedures, and is an attempt to lend the experience of other related endeavors to them. It follows the standard risk assessment format developed and tested in various national regulatory arenas. However, it assumes the existence of significant scientific and engineering knowledge commonly obtained at dredging or dredged material disposal sites from such vehicles as Environmental Impact Statements, monitoring programs, fishery studies, and engineering analyses required with permit applications. The particular value is that it demonstrates how such prior knowledge revisited within the context of an accepted framework provides a clear exposition of technical assumptions, their application within an analytical approach, and an explanation of the attendant uncertainties. The result is an ability to focus on critical path issues and to generate specific recommendations to address them within the framework.