Showing papers on "Dredging published in 1993"

Nutrient enrichment of freshwater wetlands

Abstract: In prehistoric times, freshwater wetlands formed a major part of the Dutch land surface (Pons, 1992). At present, in a landscape shaped by reclamation and urbanization, Dutch wetland reserves occur as small isolated patches in a matrix of agricultural land or as complexes formed by peat dredging, diking of oxbow lakes, etc. Freshwater dune slacks are common in the extensive coastal sand dune areas. Many wetland reserves are highly valued for their botanical and ornithological richness.

Geotechnical Factors in the Dredgeability of Sediments. Report 1. Geotechnical Descriptors for Sediments to be Dredged

Abstract: : Existing soil descriptor systems are not universally used, or even understood, by all groups involved in navigation dredging. As part of a 6-year study of this problem, a resource review has been conducted, which includes examination of the published literature and interviews with individuals knowledgeable in this area. The study indicates that the minimum soil identification test data necessary for the design, planning, and execution of dredging projects are as follows: (a) undisturbed soil mass properties, (b) disturbed soil material properties, (c) specific properties such as rheologic properties of a slurry, sedimentation rate in salt water, or bulking factors. Suggestions are made in the report for a standard set of descriptive terms and for a new Dredging Classification System.

Method for treating dredging spoils for salt contamination

Abstract: A method of treating dredging spoils for salt contamination having the steps of passing the dredging spoils to a containment area, mixing a solution of calcium and nitrate ions with the dredging spoils, reacting the solution with the dredging spoils so as to form sodium chloride, and draining the liquid component and the sodium chloride from the containment area The containment area is formed for the receipt of the dredging spoils and piping is extended from a dredge to the containment area so that the dredging spoils can be passed to the containment area The solution of calcium and nitrate ions is pumped into the flow of dredging spoils toward the containment area The step of draining includes installing a drainage tile into the containment area below a top surface of the containment area and passing the liquid component and the sodium chloride through the drainage tile to a liquid containment area The liquid containment area may be the body of water from which the dredging spoils were taken

Lower Granite Reservoir In-Water Disposal Test: Results of the Fishery, Benthic and Habitat Monitoring Program-Year 4 (1991).

Abstract: : Completion of the Lower Granite Lock and Dam Project on the Snake River in 1975 provided electrical power production, flood control, navigation and recreation to the eastern Washington-west central Idaho areas. Sediment deposition from upstream sources is jeopardizing many of the legislated uses of this project, as approximately 800,000 cubic yards (611,680 m3) of material deposit annually in the upstream portion of Lower Granite Reservoir. The large quantity of this material has necessitated dredging and consideration of in-water disposal downstream of river mile 120 (RM 120) as a management alternative. Dredging began in 1986 with land disposal and experimental in- water disposal was initiated in 1988. Two in-water disposal sites were examined; in 1988 a mid-depth site originally 20-40 ft (6.1-12.1 m) deep was modified to a depth of 6-12 ft (1.8-3.6 m) thereby creating an underwater plateau, and in 1989 an island was created immediately downstream of the underwater plateau. Monitoring of the fish and benthic communities began in 1988. This report provides information on the results of monitoring changes in the fish community and utilization of these created habitats in year-4 (1991).

Characterisation and Fate of Suspended Sediments Associated with Dredging Activities in Cleveland Bay

Abstract: Baseline investigations of trace metals in Cleveland Bay sediments highlighted elevated levels close to urbanisation, port activities and the discharge of sewage. A trace metal fractionation study on sediments from the port and dredging channel showed that a major fraction of zinc was associated with the fine sediments generated immediately after dredging and with sediments in the fluid mud layer. A significant fraction of zinc was associated with the organic and iron-bound fraction of the disturbed sediments. Characterisation of sediments collected from coral reefs before, 1 week and 1 month after dredging and dumping activities has shown that 0.5M HC1 leached zinc is a useful tracer of such activities.

Development of the venice morphological system

Abstract: The paper discusses the morphological development of the Venice Lagoon since 1850 and, on the basis of analyses of the system, presents models to simulate large scale development of the lagoon and of various sub-basins. The morphological development consists mainly in a continuous erosion of the saltmarshes and shallow areas, and a filling of canals. Also a general loss of sediment from the lagoon was observed. The main causes were identified in engineering structures like jetties, dredging of artificial canals and maintenance dredging. These works resulted in a disequilibrium of the natural hydraulic system. In addition, loss of biological protection in shallow areas, due to pollution, has contributed. Models were prepared on basis of time and partially averaged concentrations of sediment in shallow areas and canals. Averaging was carried on over a full year. This approach facilitated the building of models of various complexity, which were found to be useful tools in the analysis of the effectiveness of remedial measures .

The economics of using sediment-entrapment reduction measures in lake and reservoir design

Abstract: vii

Evaluation of Upland Disposal of John F. Baldwin Ship Channel Sediment.

Abstract: : This report describes testing and evaluation performed by the Environmental Laboratory of the U.S. Army Engineer Waterways Experiment Station (WES) on sediment from the John F. Baldwin Ship Channel, California. Test protocols from the Corps' Management Strategy for Disposal of Dredged Material were used in the present evaluation to determine the potential for migration of contaminants into the effluent, surface runoff, leachates, plants, and animals at an undetermined upland disposal site. Two composite sediment samples were collected from the Pinole Shoal and West Richmond reaches of the J. F. Baldwin Ship Channel from core depths to 47 ft (or 15.7 m) (45 ft project depth plus 2 ft overdepth. Collected sediments were transported to WES for testing.... Contaminant migration, Dredged material, Upland disposal, Contaminated sediments, Sediment testing

The Fraser River Delta, British Columbia: Architecture, Geological Dynamics and Human Impact

Abstract: The Fraser river delta is the largest delta in western Canada. It is an important coastal ecosystem and an area of explosive urban and industrial growth lying within the most seismically active zone in Canada. The main geological hazards are failures of the delta; slope and earthquake-induced liquefaction. Deposition at the river mouth contributes to slope failures, including one of more than 1×10 6 m 3 with a headscrap within 100 m of a staffed lighthouse. Previous discharge of treated sewage onto the tidal flats has led to the concentration of toxic metals and organic detritus. Causeways and other large engineering structures have altered sediment and water dispersal patterns and contributed to the erosion of some coastal habitats. Erosion of the tidal flats also may be aggravated by dredging of sand to maintain channels and provide construction material.

Sewer pipe dredging machine

Abstract: The utility model relates to a pipeline dredging device, in particular to a pipeline dredging machine which can crawl in sewers, comprising a spiral cone hinge head driven by a transmission mechanism, a propelling blade and a road wheel. Sludge is stirred by the cone hinge head to prompt the flow of the sludge to accomplish the effect of pipeline dredging. The utility model which has the advantages of simple structural design, small volume, strong applicability and high work efficiency is especially suitable for the dredging of sewers whose pipe diameters are more than 300 mm.

Uncertainty Analysis of Dredge‐Production Measurement and Calculation

Abstract: The accurate measurement of dredge production contributes to the overall efficiency and cost‐effectiveness of the dredging process. The use of production measurement systems on pipeline and hopper dredges provides dredging personnel with tools for measuring and monitoring production quantities. The accuracy of these production monitoring systems varies according to the instrumentation used and the knowledge of the sediment and water properties associated with the dredging activity. Each measurement and physical quantity associated with the calculation of dredging quantities has some uncertainty associated with it. The equations for calculating production are functions of multiple variables, each contributing some uncertainty to the final calculation. A general uncertainty analysis is applied to dredge‐production measurements and calculations. Equations describing production for hopper and pipeline dredges are reduced to uncertainty expressions using the uncertainty analysis technique. Example calculations...

Sewer with dredging device

Abstract: Disclosed is a device which can dredge clogging in sewers, comprising a sewer body and a dredging device. A sewer dredging device is additionally arranged on a universal sewer. The upward and downward movements of a sewer dredging rod and the functions of a pawl shovel extrude stemming gradually to finish dredging work.

Apparatus for dredging contaminated beds of stretches of water

Abstract: An apparatus for dredging contaminated beds of stretches of water is described, in particular beds of stretches of water having regions contaminated to a varying degree. The apparatus has a dredging device, in particular a floating dredging device with a receiving arrangement for receiving dredged material. The apparatus contains a device for determining the degree of contamination of the constituents of the bed of the stretch of water. This device enables the dredged material to be selected according to the degree of contamination before and during the actual dredging operation.

Sewer pipe pressure dredging device

Abstract: The utility model relates to a pressure dredging device for sewers The pressure dredging device for sewers can be used for various buildings, such as resident buildings, hospitals, hotels, restaurants, etc The utility model is characterized in that the pressure dredging device for sewers comprises a pressure barrel made of metal or plastic, a valve mouth positioned on the top cover of the pressure barrel and an elastic soft sealing sleeve arranged on the bottom of the pressure barrel When used for dredging clogging objects in the sewers, the utility model has the advantages of simple structure, easy processing and assembling, convenient operation and strong dredging performance No matter the openings of the sewers are large or small, the sewers are bend or straight and the distances between the clogging objects and the openings of the sewers are long or short, the sewers can be dredged rapidly and effectively, so the pressure dredging device for sewers is an ideal pressure dredging tool

Ecological evaluation of proposed dredged material from Winyah Bay, South Carolina

Abstract: The navigational channels of Winyah Bay, Georgetown Harbor, South Carolina require dredging to enable normal shipping traffic to use these areas. Before dredging, environmental assessments must be conducted to determine the suitability of this dredged sediment for unconfined, open-water disposal. The Charleston, South Carolina District Office of the US Army Corps of Engineers (USACE) requested that the Battelle/Marine Science Laboratory (MSL) collect sediment samples and conduct the required physical/chemical, toxicological, and bioaccumulation evaluations as required in the 1991 Implementation Manual. This report is intended to provide information required to address potential ecological effects of the Entrance Channel and Inner Harbor sediments proposed disposal in the ocean.

Sand mining in lower Chesapeake bay: A progress report

Abstract: A continuing series of postdredging surveys of an area in lower Chesapeake Bay from which sand has been mined indicates that the area is recovering through slow filling. Bathymetric data provide significantly more information than side‐scan sonagrams. The side‐scan data are only suggestive of slow filling of the dredged pit.

Geotechnical Factors in the Dredgeability of Sediments. Report 2. Geotechnical Site Investigation Strategy for Dredging Projects

Abstract: : The objective of a geotechnical site investigation for a dredging project is to obtain the most complete and accurate estimate of the location and character of the materials to be dredged that is possible within the limits of available time and money and of practicality. This information must then be communicated, in a readily understood manner, to all persons involved in the design, cost estimation, and construction of the project. A site investigation for dredging consists of studies of all available existing information, augmented, when necessary, by geophysical and geotechnical subbottom investigation, including the sampling and testing of soils and rock. The data are summarized in an estimated geotechnical subbottom profile. The validity of the estimated profile is dependent on the type and amount of site investigation made and on the knowledge and skill of the interpreter(s) of the data. Classification, Dredging, Description, Excavation, Dredgeability, Geotechnical soil sediments

Geological Characterization of Selected Offshore Sand Resources on the OCS, Offshore Alabama, for Beach Nourishment

Abstract: Most Alabama Gulf and estuarine shoreline is undergoing long-term erosion; threatened shorelines will need programs of replenishment and maintenance if they are to be even temporarily stabilized. Highest priority beach replenishment areas include eastern Dauphin Island; west of Perdido Pass; and west of the inlet at Little Lagoon. There are no appropriate local onshore sand sources available for any such large scale program. Sediments in the Federal waters of the EEZ were evaluated for possible sources of sand for beach nourishment. Six lithofacies were delineated based on sediment characterization, spatial framework, and environment of deposition; of these, two (Clean Sands and Graded Shelly Sands) were deemed to have highest potential as beach nourishment sources. Five offshore target areas were delineated as potential sand sources. Criteria included sand aesthetics, estimated sand volume, and sand distributions. Preliminary environmental analyses included impacts of offshore sand dredging on shelf circulation; on economic activities; and on local benthic biota. Dredging may not significantly alter background wave regimes; however, data are insufficient to model effects of major storms on a modified shelf morphology. Dredging would avoid areas of current economic activity. There would like be little long-term impact on benthic biota in the target areas. Additional work will be required to confirm or refute these preliminary findings.

The Dredging Research Program of the US Army Corps of Engineers

Abstract: The Corps of Engineers Dredging Research Program (DRP) was established in Fiscal Year 1988 as a seven-year program with the objective of developing products that reduce the cost of dredging operations. This paper explores the DRP and its accomplishments to date.

An Inexpensive Method for Vibracoring Sands and Fine-Grained Sediments in Shallow Water

Abstract: : This technical note summarizes a coring methodology used in support of a Water Injection Dredging (WID) demonstration on the Upper Mississippi River in July 1992. The WID demonstration was sponsored by the Dredging Research Program (DRP) and was a joint effort involving the U.S. Army Engineer Waterways Experiment Station (WES), the U.S. Army Engineer Districts, St. Paul and Rock Island, and Gulf Coast Trailing Company. This note describes equipment, operational procedures, and capabilities of a vibrating coring system to collect subsurface sediments. The vibrating system was developed by the WES Coastal Engineering Research Center. The method used is a refinement of a coring system developed previously by Finkelstein and Prins (1981). information provided should assist in selecting inexpensive equipment and appropriate guidelines for shallow-water coring applications.

Dredging stopper for pipeline

Abstract: The utility model discloses a pipeline dredging plug which dredges pipelines by using the self-pressure of the water source of tap water pipes, belonging to a pipeline dredging tool. The utility model comprises a tapered plug and a hose clamping ring; a hole from top to bottom is arranged in the tapered plug, the opening of the hole on the top of the tapered plug is provided with a convex hose joint, and a hose is sheathed on the hose joint and clamped by the hose clamping ring. When used for dredging soft clogging objects in sewers, the utility model has the advantages of good effect and convenient use, the structure of the pipeline dredging plug is simpler than that of an electric dredging device, and the functions of the pipeline dredging plug is better than that of a leather cup.

Dredging Related Sea Turtle Studies Along the Southeastern U.S.

Abstract: Recent studies have documented that five threatened or endangered species of sea turtles occur along the southeastern U.S. coast and are potentially affected by hopper dredging activities. Since the first reported incidents in 1980, a reduction in sea turtle deaths from dredging operations have resulted from modifications in dredging equipment, operational procedures, and management practices. More complete sea turtle life history information is necessary to develop long-term management plans as well as modifications in dredging technology to most effectively minimize sea turtle mortalities during dredging activities. A multifaceted sea turtle research effort has been initiated along the south Atlantic coast by the U.S. Army Corps of Engineers to develop these management strategies. The studies include both biological and engineering research approaches and include cooperative participation from the academic community and state and Federal agencies. Integrated trawling surveys and biotelemetry monitoring are being used to provide basic biological information on the life history, behavior, and spatial/temporal occurrence of sea turtles in south Atlantic ship channels maintained by hopper dredging. These data are being used to define and refine windows of time for dredging activities when turtles are absent or least abundant. Measures which are being tested which show potential for reducing turtles mortalities include: trawling to capture and relocate turtles; hydroacoustics to detect turtle presence; techniques to disperse turtles from the dredging pathway; a flexible turtle deflector attached to the draghead; and a new draghead design. Deterrent or dispersal techniques which show promise include seismic/acoustic pneumatic devices, sound, and physical disturbance.

Section 22 - Planning Assistance to States Program, New Hampshire Dredged Material Management Study

Abstract: : The purpose of this study is to evaluate and document the current and projected future dredging and dredged material disposal requirements of New Hampshire to provide the framework for future efforts to assess the need for an open ocean disposal site or sites. It was determined that over the next 50 years Hampton-Seabrook Harbor may require dredging of about 1,140,000 cubic yards of material; Little Harbor, depending on need, 270,000 cubic yards; Portsmouth Harbor/Piscataqua River, 640,000 cubic yards; and Rye Harbor, 132,400 cubic yards. A more complete analysis 6f future trends is contained in Section 3: 'Historic Dredging and Future Projections'.