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Dredging

Photo: COWI Marine

​Dredging covers a wide range of services related to the removal of sediments in waterways.  Dredging can be performed for either navigation or environmental enhancement purposes. 

Tasks involved

Specific tasks usually include obtaining the contours of a project site by a hydrographic survey and developing a site profile for the post-dredging bottom. COWI Marine NA obtains the survey (bathymetric) data, develops the profiles and calculates dredge volumes. These items are required by regulatory agencies for permitting, and the owner when soliciting bids for the dredging.  We take the sediment data and develop Sediment Analysis Plans, manage sediment testing, draft and manage permit applications, prepare Contract Documents for the dredging as well as provide the owner with field engineering services (project observation) during the actual work. 

Testing

Dredged material must be tested for potential contamination. COWI Marine NA coordinates testing to insure "adequate characterization" of the area to be dredged.  Additionally, we provide the Client with options and recommendations for disposal or beneficial use of the material based on the test results.

Permitting

The engineering and permitting activities necessary for undertaking a dredging project have become more complicated in recent years. COWI Marine NA has the knowledge and regulatory contacts that keep us current with these regulations.
Our dredging experts have worked as dredging contractors and construction managers and they understand the advances in dredging and disposal methodologies as well as the difficulties in locating suitable placement options.
In the past decade, the regulatory process has been further complicated by the passage of the Essential Fish Habitat amendments to the Magnuson Stevens Sustainable Fisheries Act, revisions to regional testing protocols, and application of risk assessments for dredged material pollution management.

LAST UPDATED: 04.11.2016