Description: Sediment plumes arising from marine aggregate and contract dredging are perceived by many stakeholders in the marine and coastal environment to lead to environmental impacts requiring investigation, monitoring or mitigation. However, while information on sediment plumes existed, it was disparate and difficult to use in a structured manner. CIRIA, in collaboration with a consortium made up of Posford Duvivier Environment, HR Wallingford and CEFAS, have therefore brought together the current knowledge on plumes into this one publication. Its aim is to address how plumes should be assessed, having considered the likely or possible effects of dredging operations. The report also outlines the necessary components of a structured framework for assessing the environmental effects arising from dredging plumes. It considers the steps required to inform the decision-making process, and details the data and tools required to inform the steps. This publication is an important source of information for the dredging industry, developers, regulators and conservationists concerned with marine aggregate and capital and maintenance dredging.

Keywords: coastal and marine.

Contents: 1 Introduction, 2 Legislation, regulation and stakeholders, 3 Sources of sediment plumes, 4 Plume processes and modelling, 5 Effects on the marine environment, 6 Mitigating environmental effects, 7 Towards and assessment framework, 8 Recommendations - the way forward, References, Appendices