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Showing papers on "Dredging published in 1988"


Patent
20 Jun 1988
TL;DR: In this paper, a hand-held hand-operated, diver-operator controlled and diver-operated handheld dredge head is used to move about freely in the water bed being dredged, and provides for continuously dredging the mixture of water and solids from a first body of a water and pumping the mixture to a second solids collecting body of water.
Abstract: Dredging apparatus including a diver-operator controlled and hand-held dredge head which permits the diver to move about freely in the water bed being dredged, and provides for continuously dredging the mixture of water and solids from a first body of water and pumping the mixture to a second solids collecting body of water. Submersible, hydraulic dredge pumps are used in the bodies of water. The conveying water is continuously reused in a quasi-closed system by being returned to the immediate vicinity of the nozzle or alternatively being returned through a sleeve concentrically mounted around the nozzle. The returned water discharges downwardly to counterbalance the weight of the operator-held dredge. The second, solids collecting area may take the form of a truck body into which the solid material is dumped and the dredge water passes through into a filter tank from which it is pumped and returned to the dredge area for reuse in transporting additional solids. An improved diver-operated, hand-held dredge which includes a water return means that discharges downwardly in the area of the dredge nozzle so as to counterbalance the weight of the diver-operated hand-held dredge head.

35 citations



Book ChapterDOI
01 Jan 1988
TL;DR: In order to keep waterways and ports accessible to shipping, regular dredging of the sedimented materials is necessary as mentioned in this paper in densely populated and industrial countries nearly all sediments are considerably contaminated with inorganic and organic pollutants.
Abstract: In order to keep waterways and ports accessible to shipping, regular dredging of the sedimented materials is necessary. In densely populated and industrial countries nearly all sediments are considerably contaminated with inorganic and organic pollutants. Disposal of the huge quantities of dredge spoils with minimum effect on the quality of the environment is a major problem. International conventions forbid disposal of severely contaminated sediments in the open sea. Confined disposal of contaminated dredged materials on land raises questions about groundwater quality, and about adverse effects on biota and ecosystems.

17 citations


Book ChapterDOI
01 Jan 1988
TL;DR: Aquatic ecosystems contain four potential reservoirs for contaminants: water, sediment, particulates and biota as discussed by the authors, and sediments represent a very concentrated pool of toxic substances and may themselves represent an environmental problem.
Abstract: Aquatic ecosystems contain four potential reservoirs for contaminants: water, sediment, particulates and biota In particular, sediments represent a very concentrated pool of toxic substances and may themselves represent an environmental problem The dredging and/or disposal of sediments in dumping areas may adversely affect water quality and the health of aquatic organisms

16 citations



01 Dec 1988
TL;DR: In this paper, the evaluation of hydraulic conditions and sediment migration associated with the dredging and dredged material disposal alternatives was proposed for the upper Acushnet River Estuary upstream of New Bedford Harbor, Massachusetts.
Abstract: : This report documents the evaluation of hydraulic conditions and sediment migration associated with the dredging and dredged material disposal alternatives proposed for the upper Acushnet River Estuary upstream of New Bedford Harbor, Massachusetts. Dredging and onsite disposal is one remedial measure being considered by the US Environmental Protection Agency. Assessments of sediment and contaminant migration beyond the upper New Bedford Harbor from proposed dredging and disposal alternatives were made based on field, laboratory, and various model studies. The upper estuary was found to be depositional and a reasonably efficient sediment trap. Total suspended material (TSM) concentrations were very low in the system. CAD cell, Contaminant, Deposition, Disposal, Dredging, Migration, Numerical transport model, Resuspension, Sediment, Settling velocity, Water tunnel, Total suspended material.

9 citations


01 Jan 1988
TL;DR: In this paper, the Vembanad lake is divided into zones for studying the pattern of exploitation and seed production and the results are presented in the case study, where the effect of manual exploitation of subsoil deposits ranging from 41,000 to 70,000 t/year and of degrading on the clam beds is also presented.
Abstract: The Vembanad lake, covering about 200 sq. km, it supporting a rich fishery of clams mainly constiiuted by Villorlta cyprlnoldes vac Cochinensis and the total production Is around 25,000 t/year- The lake is divided into s'x zones for studying the pattern of exploitation and seed production and the results are presented in the paper. The effect of manual exploitation of subsoil deposits ranging from 41,000 to 70,000 t/year and of dredging on the clam beds is also presented with comments on the development possibilities in the sector based on this case study.

9 citations



01 Nov 1988
TL;DR: In this paper, the authors performed column tests on three sediments: the composite, the hot spot, and the capping sediments, and found that their settling behavior was typical of other marine sediments if hydraulically dredged and placed in a CDF.
Abstract: : One alternative for cleanup of the New Bedford Harbor Superfund site is dredging the contaminated sediments and placement into an upland or intertidal confined disposal facility (CDF). The conceptual design of either facility requires an evaluation of the settling properties of the dredged material to estimate storage requirements and effluent suspended solids concentrations. Suspended solids reduction beyond gravity settling may be achieved by chemical clarification. Laboratory column tests were performed on three sediments: the composite, the hot spot, and the capping sediments. Their settling behavior was observed to be typical of other marine sediments if hydraulically dredged and placed in a CDF. The compression test data were used to develop the initial storage requirements. The zone settling velocity was found not to be a controlling factor in the storage design; therefore, zone tests were not Performed on the hot spot and capping sediments. The flocculent test indicated that the suspended solids will settle by gravity. The chemical clarification test was conducted to further reduce those suspended solids left in the effluent.

8 citations


01 Feb 1988
TL;DR: In this article, field demonstrations were conducted at Calumet Harbor, Illinois, to evaluate the water quality impacts of different dredging and disposal equipment, including the use of a submerged diffuser designed to place material close to the bottom and reduce the exit velocities.
Abstract: : As part of a larger effort to evaluate dredging and disposal options of contaminated material at Indiana Harbor, Indiana, field demonstrations were conducted at Calumet Harbor, Illinois, to evaluate the water quality impacts of different dredging and disposal equipment. This report documents the Calumet Harbor field study and presents the results. The dredging equipment evaluations were conducted to evaluate the sediment resuspension characteristics of a cutterhead suction dredge, clamshell dredge, and Dutch-designed matchbox suction head dredge. The Calumet Harbor demonstration represents the first use of the matchbox suction head in this country. The disposal equipment demonstration included the use of a submerged diffuser designed to place material close to the bottom and reduce the exit velocities. The Calumet Harbor demonstration indicated that the clamshell dredge generated the largest suspended sediment plume affecting the entire water column. The cutterhead and matchbox dredges were successful in limiting sediment resuspension to the lower portion of the water column with the cutterhead slightly outperforming the matchbox. Improved instrumentation and increased operator experience with the matchbox suction head dredge may help in further reducing sediment resuspension. The submerged diffuser proved to be successful in limiting sediment resuspension to the lower portion of the water column and significantly reducing discharge velocities.

7 citations


Journal ArticleDOI
TL;DR: In this article, the authors outline the procedures and practices adopted by the Norwich Division of Anglian Water (AW) in implementing the policy decision of AW to undertake River Corridor Surveys (RCSs) prior to all major dredging works.
Abstract: The year 1987-88 has been designated as European Year of the Environment (EYE). It is against this background that the paper has been prepared, to illustrate how the differing requirements of the river engineer and the conservationist can be intergrated into a working practice for dredging. The paper outlines the procedures and practices adopted by the Norwich Division of Anglian Water (AW) in implementing the policy decision of Anglian Water (AW) in implementing the policy decision to undertake River Corridor Surveys (RCSs) prior to all major dredging works. The requirements for the survey and the methodology are discussed, together with the reports produced and the audits carried out. Their impact and implications on the operational aspect of undertaking the dredging works, and the method used to prepare a working site plan and monitor the site are detailed, and some indication of costs is given.


01 Oct 1988
TL;DR: A series of reports describing the results of the EFS is presented in this paper, including baseline mapping, geotechnical investigations, hydrodynamics, sediment resuspension and transport, contaminant releases to surface and ground water, dredging equipment and controls, effluent treatment, solidification/stabilization of dredged material, confined disposal facility design, contained aquatic disposal facility, and cost estimates for the alternatives evaluated.
Abstract: : Sediments in the New Bedford Harbor and Acushnet River Estuary have been contaminated with polychlorinated biphenyl compounds and heavy metals. The high levels of contamination have resulted in the New Bedford Harbor being placed on the National Priorities List of the Nation's worst hazardous waste sites. Efforts are under way to develop and implement remedial actions for protection of the environment under the Federal Superfund Program. This report is an introduction to and an overview of a series of reports describing the results of the EFS. It presents the overall study objectives and scope of work, describes the objectives and scope of the 10 EFS tasks, and presents a brief synopsis of the other 11 reports in the series. The EFS technical approach used field data collection activities, literature reviews, laboratory (bench-scale) studies, and analytical and numerical modeling techniques to assess engineering feasibility and develop conceptual alternatives for dredging and dredged material disposal. Technical and engineering issues addressed by the EFS included baseline mapping, geotechnical investigations, hydrodynamics, sediment resuspension and transport, contaminant releases to surface and ground water, dredged material settling properties, dredging equipment and controls, effluent treatment, solidification/stabilization of dredged material, confined disposal facility design, contained aquatic disposal facility design, and cost estimates for the alternatives evaluated.

Book ChapterDOI
01 Jan 1988
TL;DR: The US Army Corps of Engineers (CE), in fulfilling its mission to maintain, improve, and extend these waterways, is responsible for the dredging and disposal of large volumes of sediment each year.
Abstract: Navigable waterways of the United States have played a vital role in the nation’s economic growth through the years. The US Army Corps of Engineers (CE), in fulfilling its mission to maintain, improve, and extend these waterways, is responsible for the dredging and disposal of large volumes of sediment each year. Dredging is a process by which sediments are removed from the bottom of streams, rivers, lakes, and coastal waters; transported via ship, barge, or pipeline; and discharged to land or water. Annual quantities of dredged material average about 290 million m3 in maintenance dredging operations and about 78 million m3 in new, work-dredging operations with the total annual cost now exceeding $250 million.

01 Oct 1988
TL;DR: A series of reports describing the results of the EFS have been published as discussed by the authors, which used field data collection activities, literature reviews, laboratory (bench-scale) studies, and analytical and numerical modeling techniques to assess engineering feasibility and develop conceptual alternatives for dredging and dredged-material disposal.
Abstract: Sediments in the New Bedford Harbor and Acushnet River Estuary have been contaminated with polychlorinated biphenyl compounds and heavy metals. The high levels of contamination have resulted in the New Bedford Harbor being placed on the National Priorities List of the Nation's worst hazardous waste sites. Efforts are under way to develop and implement remedial actions for protection of the environment under the Federal Superfund Program. This report is an introduction to and an overview of a series of reports describing the results of the EFS. It presents the overall study objectives and scope of work, describes the objectives and scope of the 10 EFS tasks, and presents a brief synopsis of the other 11 reports in the series. The EFS technical approach used field data-collection activities, literature reviews, laboratory (bench-scale) studies, and analytical and numerical modeling techniques to assess engineering feasibility and develop conceptual alternatives for dredging and dredged-material disposal. Technical and engineering issues addressed by the EFS included baseline mapping, geotechnical investigations, hydrodynamics, sediment resuspension and transport, contaminant releases to surface and ground water, dredged material settling properties, dredging equipment and controls, effluent treatment, solidification/stabilization of dredged material, confined-disposal-facility design, contained aquatic-disposal-facility design, and cost estimates for themore » alternatives evaluated.« less

01 Dec 1988
TL;DR: In terms of cost, water injection dredging can often be compared very favorably with conventional dredging methods, since the dredged material is transported by a naturally occurring density current, a result of differences in density between a mixture of water and sediment and, on the other, water.
Abstract: In terms of cost, water injection dredging can often be compared very favorably with conventional dredging methods, since the dredged material is transported by a naturally occurring density current--a result of differences in density between, on the one hand, a mixture of water and sediment and, on the other, water. Jet penetration, jet dispersal, density flow and sedimentation play an important role in this type of dredging process. These have been explored with the aid of theoretical research, scale model tests and in situ measurements. Some of these results are described. The water injection dredging theory has been put into practice using the water injection vessel JETSED, and some of the working methods employed are briefly considered. A number of case studies illustrate the capacity and capabilities of the JETSED.

Patent
10 Feb 1988
TL;DR: In this paper, an improved hydraulic dredging device, comprising a separate type control traction system, a dredging head by ploughing, scraping, blowing and sucking, and a floating box, is presented.
Abstract: The utility model discloses an improved hydraulic dredging device, comprising a separate type control traction system, a dredging head by ploughing, scraping, blowing and sucking, and a floating box. The floating box is provided with a dredging pipeline which is formed by a flexible connector made of rubber plus rib among steel pipes and a floating crane dredging pipe. The separate type control traction system is characterized in that traction apparatuses can be controlled and arranged dispersively, traction forces can be directly applied on the dredging head, and the underwater position of the dredging head can be controlled by a lifting cable hoist. The dredging head by ploughing, scraping, blowing and sucking is characterized in that silt can be directly plaughed by ploughs, the plaughs, silt inlets and arched silt scraping plates are symmetrically arranged, and a movable guide plate and a nozzle are arranged in the dredging head. The flexible connector made of rubber plus rib is characterized in that a steel bar is used as a hooping bar, a steel wire rope which is a longitudinal bar can be formed into a pipe network frame, and a pipe wall can be formed by binding with rubber. The improved hydraulic dredging device is applicable for cleaning silt in reservoirs.

Journal Article
TL;DR: In this article, the authors described sediment transport in the Buffalo River as a contribution toward planning for dredging or in-place containment of the contaminated bed sediments, and extended earlier analysis in the following directions: i) more detailed consideration of the characteristics and behavior of the fine sediments of the river bed; ii) incorporation of fine sediment scour into HEC-6 program; iii) longer-term transport simulation aimed at evaluating the viability of the bury-in-place option for managing contaminated sediments.
Abstract: This paper documents part of a project which sought to characterize sediment transport in the Buffalo River as a contribution toward planning for dredging or in-place containment of the contaminated bed sediments. It extends earlier analysis in the following directions: i) more detailed consideration of the characteristics and behavior of the fine sediments of the river bed; ii) incorporation of fine sediment scour into HEC-6 program; and iii) longer-term transport simulation aimed at evaluating the viability of the bury-in-place option for managing contaminated sediments.

01 Oct 1988
TL;DR: In this article, the thickness of capping material needed to chemically sequester the polychlorinated biphenyl (PCB)-contaminated New Bedford Harbor sediment from the overlying water column and aquatic biota was assessed in a small-scale predictive test.
Abstract: : The thickness of capping material needed to chemically sequester the polychlorinated biphenyl (PCB)-contaminated New Bedford Harbor sediment from the overlying water column and aquatic biota was assessed in a small-scale predictive test. Changes in the overlying water concentrations of dissolved oxygen, ammonium-nitrogen, and orthophosphate-phosphorus were monitored following isolation of the water column from the atmosphere by placing a 4-cm layer of mineral oil on the water surface. The chemical tracers (ammonium- nitrogen and orthophosphate-phosphorus) were selected for their mobility under anaerobic conditions, ease of measurement, and generally high concentrations in contaminated dredged material compared with clean sediments. The chemical tracers were used to evaluate the efficiency of the capping material in preventing transfer of contaminants from New Bedford Harbor sediment into the overlying water column.

01 Dec 1988
TL;DR: In this article, the impact of dredging on the environment as a function of the dredging method, soil type and water current conditions is discussed, along with the data processing techniques used.
Abstract: During maintenance dredging operations in Dutch harbors, investigations have been carried out to assess the level of resuspension of sediment due to dredging activities. This research is intended to create an overview of the impact of dredging on the environment as a function of dredging method, soil type and water current conditions. This article indicates the background to the research and the technical aspects of the turbidity phenomenon. The method of investigation and techniques applied are discussed along with the data processing techniques used.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the long term erosion of Perdido Key due to a general negative sediment budget exacerbated by the dredging of a navigation channel at the updrift margin of the Key.

01 Aug 1988
TL;DR: In this article, the authors evaluated the usefulness of the Standard Elutriate Test for estimating the release of contaminants at or near the point of dredging and found that the test satisfactorily predicted, within one order of magnitude, the release at the four sites evaluated.
Abstract: The overall objective of this study was to evaluate the usefulness of the Standard Elutriate Test for estimating the release of contaminants at or near the point of dredging. The Army Engineer Waterways Experiment Station collected field data and performed laboratory analyses of samples from four dredging sites for purposes of the evaluation. Study of the data obtained indicated that the elutriate test satisfactorily predicted, within one order of magnitude, the release of contaminants at the point of dredging for the four sites evaluated. Predictions were generally conservative.

ReportDOI
01 Sep 1988
TL;DR: In this article, a sand bypassing feasibility analysis for the St. Mary's River entrance channel was conducted in connection with the development of the US Navy's Trident submarine base in King's Bay, GA.
Abstract: : This report provides a sand bypassing feasibility analysis for the St. Mary's River entrance channel. The study was conducted in connection with the development of the US Navy's Trident submarine base in King's Bay, GA. The analysis found that sand bypassing would not provide a significant reduction in the total amount of maintenance dredging required in the entrance channel, but could provide for the a cost-effective means of dredging disposal and beach nourishment.

Patent
Yutaka Nishikawa1
24 May 1988
TL;DR: In this article, a method of and apparatus for continuously dredging sludge deposited on an underwater bed, at a high density of the sludge, according to which digging and scooping devices are placed in an airtight hood opened at its bottom, which is applied on the intended underwater bed and into which air is then introduced to obtain a condition in which water is removed out of the hood, and the digging and scouring devices are then put into operation, whereby dredging is effected at high efficiency in that the content of water in sludge being dredged is suppressed to a
Abstract: A method of and apparatus for continuously dredging sludge deposited on an underwater bed, at a high density of the sludge, according to which digging and scooping devices are placed in an airtight hood opened at its bottom, which is applied on the intended underwater bed and into which air is then introduced to obtain a condition in which water is removed out of the hood, and the digging and scooping devices are then put into operation, whereby dredging is effected at a high efficiency in that the content of water in sludge being dredged is suppressed to a minimum, the sludge being transferred under pressure in a state of containing substantially no additional water than it naturally contains.

01 Nov 1988
TL;DR: In this article, the results of an evaluation of dredging equipment and techniques for removal of highly contaminated sediments from the upper estuary of the Acushnet River, a portion of the New Bedford Harbor Superfund Project Site conditions as related to dredge selection and operation, factors considered in selection of equipment, various dredge types considered for use, and operational procedures and controls for sediment resuspension during dredging are described.
Abstract: This report presents the results of an evaluation of dredging equipment and techniques for removal of highly contaminated sediments from the upper estuary of the Acushnet River, a portion of the New Bedford Harbor Superfund Project Site conditions as related to dredge selection and operation, factors considered in selection of equipment, various dredge types considered for use, and operational procedures and controls for sediment resuspension during dredging are described Each of the dredge types is ranked according to the following criteria: compatibility for full-scale cleanup, availability, safety, potential for sediment resuspension, maneuverability, cleanup precision, cost and production flexibility, required water depth for operation, ability to access the site, and compatibility with disposal options

01 Mar 1988
TL;DR: In this article, the size and concentration of sediment plumes measured in field studies of selected dredging equipment are described, which is useful when sediment resuspension must be minimized because of adverse environmental impacts which may include the release of sedimentassociated chemical contaminants.
Abstract: : The size and concentration of sediment plumes measured in field studies of selected dredging equipment are described This information is useful when sediment resuspension must be minimized because of adverse environmental impacts which may include the release of sediment-associated chemical contaminants The information presented here is intended to supplement and update information given in a previous technical note on the same topic (Naves 1986a)


01 Jan 1988
TL;DR: In this paper, the authors analyzed lakebed sediments obtained prior to dredging activities in Lake Springfield for trace metal, organic chemistry, and physical characteristics for a preliminary assessment of the potential pollution problems that could occur as a result of dredging.
Abstract: Illinois lakes serve as a major sink of the sediment and pollutants transported by streams. Sediments and pollutants accumulate in lakes and cause use impairement due to volume loss, shallowness, turbidity, habitat destruction, eutrophication, taste and odor problems, and loss of aesthetic values. Lake dredging is a technique for removing accumulated sediments and rehabilitating lost lake resources. Although lake dredging has been performed in the past on Illinois lakes, these projects have been on a relatively small scale. The amount of lake dredging is expected to increase in the future as older lakes experience cumulative use impariment over time. This research project documented past dredging programs in Illinois and assessed the potential effects of lake dredging on Lake Springfield, one of the state's largest man-made water supply lakes. The city of Springfield plans to dredge 2.7 million cubic yards of sediment from their lake over the period 1987 through 1989. This is the largest dredging project to date in the state and represents the scale of future dredging projects anticipated at other lake sites in the state. This research analyzed lakebed sediments obtained prior to dredging activities in Lake Springfield for trace metal, organic chemistry, and physical characteristics for a preliminary assessment of the potential pollution problems that could occur as a result of dredging. The results show detectable levels of organic insecticides, herbicides, and trace metals in the lakebed sediments; however, the concentrations of these constituents are relatively low. This research concluded from the observed concentrations of contaminants in the sediments of Lake Springfield that disturbance of these sediments by dredging (using conventional dredging techniques to minimize resuspension) could cause some localized elevated turbidity levels. However, there is little evidence that the contaminants in the sediment could cause measurable contamination of the water in the lake. Further research is needed to measure the actual release of contaminants to the lake water during the dredging operation in order to more accurately assess the effects of dredging on the use of the lake and the lake's water quality.

Journal Article
TL;DR: In this article, the relationship between operating parameters and suspended sediment levels at the cutterhead is examined, based on several model and field studies Parameters studied include rotational speed, suction velocity, swing velocity, thickness of cut, ladder angle, sediment size and cutter size.
Abstract: Over the years, many port and harbor sediments have accumulated toxic substances During dredging, varying quantities of these contaminated sediments are resuspended in the water and can be harmful to marine plants and animals, and to humans The source of such water column contamination, resuspension at the cutterhead dredge, is thought to depend upon environmental conditions, dredge plant and sediment characteristics and dredge operating parameters In this article, the relationship between these operating parameters and suspended sediment levels at the cutterhead are examined, based on several model and field studies Parameters studied include rotational speed, suction velocity, swing velocity, thickness of cut, ladder angle, sediment size and cutter size

Journal ArticleDOI
TL;DR: The results of dredging at Liberty Lake offer some valuable lessons for the conduct of sediment removal operations for lake restoration objectives as discussed by the authors. But, the results of the dredging were not as successful in reducing internal phosphorus loading as anticipated, as macrophyte regrowth has been rapid.
Abstract: The results of dredging at Liberty Lake offer some valuable lessons for the conduct of sediment removal operations for lake restoration objectives. It was planned that approximately 50 ha were to be dredged at Liberty Lake. Differing dredge patterns were produced by two different contractors who performed the actual work, which included the removal of over 4 × 105 m3 of sediment material. In Area 1, deeply dug trenches were separated by undredged rows, while the bottom contour was more uniform in Area 2. The trenching pattern resulted in an actual dredged area of only about 21 ha. Because of slumping of undredged material into the trenches, and because of the remaining pool of high-phosphorus sediments, the dredging at Liberty Lake, especially in Area 1 was not as successful in reducing internal phosphorus loading as anticipated. In addition, macrophyte control from the dredging was not realized in Area 1, as macrophyte regrowth has been rapid. Some considerations for sediment removal in lake res...