Dredging

About: Dredging is a research topic. Over the lifetime, 3300 publications have been published within this topic receiving 28325 citations.

Multi-purpose vessel and method for recovering, storing and/or offloading material in a dredging operation

Abstract: A method of building a levee or an island is disclosed. The method includes dredging material from a surface of a body of water with a dredge assembly mounted to a hull and supporting a hopper with the hull. The hopper is adapted to receive the material. The hopper includes a floor with a portion of the floor moveable to permit movement of the material in the hopper, and depositing at a desired location dredge material from the dredge using a transfer conveyor.

The Punaise: A Remotely Operated Submerged Dredging System

Abstract: The Punaise (Dutch for “thumbtack”) is a remotely operated, water-tight, submerged dredge pump system that can dredge sediments from the seafloor without impact to navigation or being affected by storms. The first Punaise was originally designed for silt removal and used in 1991 in The Netherlands. Since then, a second system has been constructed to remove sand for beach nourishment activities. PinPoint Dredging Company, a partnership of J.G. Nelis B.V., Ballast Nedam Dredging B.V. and Boskalis International B.V., operates the Punaise system and has most recently used it at beach nourishment project on the Dutch coast during the autumn of 1996. Though the Punaise has not yet operated in the U.S., PinPoint Dredging Company and the State of New York planned to demonstrate the Punaise technology for inlet bypassing, but a combination of procedural delays and limited geotechnical/geological information prevented implementation within the available environmental time frame. This paper was written with the intention of presenting a new dredging technology to the US and is funded by the USAE Waterways Experiment Station’s Dredging Operations and Environmental Research (DOER) Program. The Innovative Technologies Focus Area within DOER is tasked with identifying new and innovative dredging technologies for potential demonstration and monitoring to help USAE Districts conduct dredging more efficiently. This paper is not intended to be an endorsement for any particular technology or dredging company but merely to identify a technology with potential application in the US. Permission was granted by the Chief of Engineers to publish this paper. The paper was presented at the WEDA XVIII Conference in Charleston, South Carolina, June-July 1997, and was first published in the Proceedings of the conference. It received the “Most Outstanding Paper”award from the Dredging Contractors of America. The paper is reprinted here in a slightly revised form with permission. Terra et Aqua – Number 69 – December 1997 20 Gregory Williams is a Research Hydraulic Engineer in the Coastal and Hydraulics Laboratory at the US Army Engineer Waterways Experiment Station (WES) in Vicksburg, Mississippi. He has worked in the Dredging Research Program, Wetlands Research Program and the current Dredging Operations and Environmental Research Program. He received a BSc in Civil Engineering from North Carolina State University, an ME in Coastal Engineering from Old Dominion University, and is currently pursuing a PhD in Ocean Engineering at Texas A&M University. Kris Visser has a BSc in Civil Engineering and has worked for over 25 years with various Dutch dredging companies. From 1989 on, he has been General Manager of J.G. Nelis responsible for the development of the Punaise. In 1995, when the PinPoint Dredging Company was formed by Boskalis, Ballast Nedam Dredging and J.G. Nelis, he became the coordinator of all activities related to this dredge. Gregory L. Williams

Use of the Sediment Quality Triad to Assess Metal Contamination in Freshwater Superficial Sediments from the Le An River, China

Abstract: By integrating data on the chemistry, toxicity and benthic community structure, the sediment quality triad was used to evaluate the current situation of superficial sediments from the Le An River. This river has been strongly polluted with large amounts of copper, lead and zinc in waste water discharging from riparian mining and smelting activities. The response of the benthic environment was illustrated by ratio-to-reference (RTR) scale in corresponding triaxial graph. From upstream to downstream, the response intensity of three components showed sectional characteristics. The upstream area was relatively clean due to less disturbance. Within the middle stream area, extreme toxicity and serious deterioration of the benthic community structure could be mainly ascribed to strong acidity in drainage and high concentrations of multiple metals in superficial sediments, especially copper. Because of the river self-purification capability, pollution gradually declined and the sediment quality began to recover downstream. The situation was closely associated to the distribution of major pollution sources, therefore, source control and dredging operation on contaminated sediments in the middle stream area are required urgently.

Cartographic ally controlled water channel dredging method detects position of dredger during dredging operation for updating vector map of dredged water channel

Abstract: The dredging method uses a floating dredger, with the water scanned to provide a depth profile which is correlated with map data for providing a vector map, the position and alignment of the dredger and the device for removing material from the water bed detected during the dredging operation, e.g. via a global positioning satellite system, to allow the vector map to be updated.

Restoration of an Eroded Estuarine Foreshore Using Cohesive Dredge Material, Orwell Estuary, UK

Abstract: Cohesive sediment recharge has considerable potential as a means of restoring estuarine shores on account of the large volumes of mud raised through maintenance dredging. However, few direct foreshore placements of muddy material have been undertaken to date. This paper evaluates a pioneering sediment recharge in the Orwell estuary (eastern UK), along a degraded mud-gravel foreshore backed by a seawall protecting agricultural land. Recharge was undertaken in December 1997 and involved placement of a retaining bank of potentially mobile gravel, which was filled with 22 x 10(3) m(3) muddy maintenance dredgings. Morphodynamic behaviour of the mud and gravel deposits over a 10 year period has been dominated by in situ dewatering and compaction of the mud, landward reworking of the enclosing gravel, and partial return of the mud to the wider estuarine system. Landward 'roll over' of the gravel has reduced the width of the newly created mudflat by around 60%, such that this is now only 15 to 25 m wide. However, top-up recharges of mud in 2000 and 2003 raised elevations to the extent that around 80% of the mud area has been colonized by a diverse community of saltmarsh halophytes. This study demonstrates the feasibility of direct placement of cohesive dredge material on low wave energy estuarine foreshores as a means of reducing damage to flood defence infrastructure and restoring degraded mud flat and saltmarsh habitats over a decadal timescale.