Topic
Dredging
About: Dredging is a research topic. Over the lifetime, 3300 publications have been published within this topic receiving 28325 citations.
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01 Jan 1991
TL;DR: In this paper, a new method for underwater pipe burial has been developed and field-tested - fluidized self-burial using pull-down with earth anchors, which has been shown to save about half the cost over a 20-30 year period.
Abstract: Conventional dredging for channel maintenance and 'mining' of offshore sand for beach restoration and renourishment 'moves the pump to the sand'. The new technology of fluidization 'moves the sand to the pump'. The fluidized sand/water slurry flows down a gentle slope to a mid-point where it is easily pumped to a nearby eroded beach - a form of sand bypassing. Beachface dewatering (the 'reverse' of fluidization) works by pumping water out of filter-covered slotted pipes buried parallel to the beach strandline. Down-drift beaches are not harmed, as the newly widened beach sheds sand continually to 'feed' downdrift beaches. A new method for underwater pipe burial has been developed and field-tested - fluidized self-burial using 'pull-down' with earth anchors. Annualized costs over a 20-30 year period are about half that of conventional methods.
9 citations
Patent•
14 Aug 1975
TL;DR: In this paper, a hydraulic dredge for recovering manganese nodules from the sea bottom includes a transfer station suspended from a mother ship at a fixed depth from the surface and a dredging tool assembly suspended from winches on the transfer station by means of cables whose effective lengths are varied in response to depth signals from sensors respectively associated with the cables on respective parts of the tool assembly to keep the same contiguously adjacent the sea floor surface in parallel relationship.
Abstract: A hydraulic dredge for recovering manganese nodules from the sea bottom includes a transfer station suspended from a mother ship at a fixed depth from the surface and a dredging tool assembly suspended from winches on the transfer station by means of cables whose effective lengths are varied in response to depth signals from sensors respectively associated with the cables on respective parts of the tool assembly to keep the same contiguously adjacent the sea floor surface in parallel relationship.
9 citations
TL;DR: A modified elutriate test has been developed to predict levels of both dissolved and particulate associated contaminants in containment area effluents, and can be used to determine the need for effluent treatment.
Abstract: Significant advances have been made in recent years on dredging equipment, operating techniques, and disposal methods for contaminated sediments. Preliminary guidance is available for selecting dredges and operational techniques to minimize resuspension of contaminated sediments during dredging. This is important since research results have indicated that most contaminants are attached to the clay-sized particles and natural organic solids found in lakes. Detailed guidance is available for designing dredged material containment areas based on the settling and physical properties of sediments. A modified elutriate test has been developed to predict levels of both dissolved and particulate associated contaminants in containment area effluents. This test can be used to determine the need for effluent treatment. Guidelines are available for designing treatment systems to clarify the effluent from containment areas. This paper provides information on selecting dredging equipment and operational techni...
9 citations
TL;DR: In this article, the authors quantify the spreading of suspended sediment from underwater blasting and subsequent dredging of bedrock and to understand the physical processes governing the spread of sediment due to underwater blasting.
9 citations
01 Jul 2005
TL;DR: In this paper, acoustic-based seagrass mapping techniques were used to generate detailed maps of the eelgrass distribution before and after dredging operations, and two types of potential impacts were examined: direct impacts involved physical removal of vegetation along with the dredged sediments.
Abstract: : While speculation on effects of dredging on seagrass beds is plentiful, actual empirical data documenting these effects are not. In this study, acoustic-based seagrass mapping techniques were used to generate detailed maps of seagrass distribution before and after dredging operations. Eelgrass (Zostera marina) within Scituate Harbor, MA, was monitored during mid-summer in 2001, 2003, and 2004; navigation maintenance dredging of the harbor was performed during fall 2002. Similar surveys were also performed during the same timeframe at an undredged harbor near Wood Island, ME. Two types of potential impacts were examined. Direct impacts involved physical removal of vegetation along with the dredged sediments. Indirect impacts in adjacent undredged areas may occur as a result of increased turbidity and/or siltation associated with dredging activities. Using hydroacoustic techniques, the authors were able to easily map and quantify direct impacts to eelgrass resources. Assessment of indirect impacts, however, was more complex. In the first post-dredging survey, a substantial reduction in coverage occurred in adjoining undredged areas, suggesting possible indirect impacts. This was followed by a modest recovery between the first and second post-dredging years. However, monitoring of other undredged sites within the region showed natural year-to-year variations in eelgrass coverage to be almost as large as those occurring at the dredged site. Results emphasize the need for long-term data to discern any potential effects of dredging on seagrass dynamics as opposed to a host of other factors contributing to high variability in measured parameters.
9 citations