The Ecological Consequences Of Dredging And Dredge Spoil Disposal In Canadian Waters

Author : P. Lane and Associates
Publisher :
ISBN 13 :
Total Pages : 9 pages
Book Rating : 4.:/5 (956 download)

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Download or read book Impacts of Dredging and Spoil Disposal written by P. Lane and Associates and published by . This book was released on 1989 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Dredging of bottom sediments and glacial till for bridge siting and maintenance of navigable waterways destroys benthic fauna and their habitats, and inevitably resuspends some fine particulate matter .... Provided the sediments are not grossly contaminated with heavy metals or organic pollutants, environmental impacts of dredging and spoil disposal are believed to be localized and short-term in nature. Most pollutants are associated with fine-grain, organic particles that settle very slowly. Depending upon the physical oceanographic regime, the various contaminants in dredged fines can be transported long distances. Accumulations well above "background" concentrations are usually restricted to semi-enclosed basins and other poorly-mixed areas, i.e. sites with muddy sediments. Sediments in many industrialized harbours have such high levels of contaminants that governments often prohibit or restrict their disposal. A brief review of the Canadian Government regulations pertaining to ocean disposal of waste materials immediately follows these introductory paragraphs (Section 2). The proposed bridge would involve a maximum dredging volume of 300,000 m3 if the foundations are taken to bedrock .... Depending on the foundation type selected by the developer the actual dredging value could be considerably less than this. While this may suggest the possibility of high risks from pollutant concentrations, most of the fines are contained in glacial till beneath a shallow veneer of surface sediments .... Surficial sediments, where present, are composed primarily of sands and gravel ... and are unlikely to contain large quantities of anthropogenic contaminants. High current activity in the Strait frequently shifts these deposits about and negates any appreciable accumulation of fine, pollutant-rich particles. Some of these particles are invariably buried with larger particles in sand and gravel ripples, but are periodically released back to the water column by natural processes. In order to assess whether dredging activities and spill disposal will pose any high-level risks to biota in Northumberland Strait, a review and appraisal of existing chemical data from the proposed fixed-link corridor, as well as surrounding waters, was carried out. Much of this data has been summarized here, and compared with existing Canadian Government standards or background concentrations normally found in Atlantic Canada (Section 3)"--Pages 2-3.