Hydraulic dredging uses a dredge head and hydraulic pump to fluidize the contaminated sediment in place, and then pump the slurry to a handling location. As such, mechanical dredging is optimal in locations where sediment disturbance doesn’t lead to significant re-suspension into the water column (for example, in locations with coarse-grained and sandy sediments). On-site treatment (such as dewatering) of the sediment is often required, although water content of dredged sediments is typically lower with mechanical dredging than with hydraulic dredging techniques. Mechanical dredging involves removal of the sediment using a bucket attached to a crane. Two types of sediment dredging technologies are considered in remediation projects: mechanical and hydraulic. All associated risks must be carefully considered during the design phase to develop a successful plan for mitigating risks and reversing short-term disturbances. However, dredging is a highly invasive remediation option, and can have long-term negative impacts on aquatic habitats and benthic species if appropriate control measures and best management practices are not used (ITRC, 2014 Manap and Voulvoulis, 2014). In addition, fewer limitations are placed on future site uses, as compared to in situ remediation where contaminated sediments remain in place. The key advantages of dredging over other remediation options are that dredging typically requires shorter timelines to complete and results in greater certainty about the long-term effectiveness of remediation activities. Dredging, followed by treatment and disposal of the contaminated material, has become one of the most commonly implemented methods for sediment remediation in North America. The terms dredging, environmental dredging, or underwater excavation refer to the removal of contaminated sediments from a water body for purposes of sediment remediation. Potential impacts of the application of the technology on human health.Measures to improve sustainability or promote ecological remediation.
Complementary technologies that improve treatment effectiveness.Limitations and Undesirable Effects of the Technology.Secondary by-products and/or metabolites.Long-term considerations (following remediation work).Applications to sites in northern regions.Other information recommended for detailed characterization.Recommended trials for detailed characterization.Recommended analyses for detailed characterization.
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