Environmental Aspects Of Dredging Activities In The Great Lakes

Expanding a port, deepening a navigation channel or creating new land for development, introduces changes to our physical, social, economic and political environment. Changes may result from events during the construction process, or relate to the nature of the completed structure. Changes can be positive or negative, short-term or long-term, and may affect the immediate vicinity of the project or a larger geographical area. Predicting and assessing all possible effects of a planned dredging activity in a scientifically-sound and reliable manner is essential, so that appropriate control measures can be taken to avoid or mitigate unwelcome impacts. This book provides guidance for a complete holistic environmental evaluation procedure and for the design and implementation of environmental control measures. The book is of particular interest to engineers, government agencies and port authorities, as well as civil engineering consultants and contractors involved in planning and designing dredging, maritime infrastructure and fluvial projects.

During spring 1977, water was sampled in the Grand River, which runs through the State of Michigan, to estimate the increased loads of polluting and enriching substances caused by dredging the river channel near its mouth at Lake Michigan. Results indicate that sedimentary material disturbed during the dredging process is carries out to the lake. On an annual basis, the increase in loading is approximately 1 percent for all variables measured; however, during the period of dredging (about 1 week), the increases are approximately 30 percent. The effects of these events on the nearshore ecology are not known at present.