Showing papers on "Dredging published in 1982"

Lake restoration by sediment removal

Abstract: Fresh water lake sediment removal is usually undertaken to deepen a lake and increase its volume to enhance fish production, to remove nutrient rich sediment, to remove toxic or hazardous material, or to reduce the abundance of rooted aquatic plants. Review of more than 60 projects and five case histories reveals that the first three objectives are usually met through sediment removal. Dredging to control aquatic plants has not been well documented. Disadvantages of dredging include cost, temporary phosphorus release from sediment, increased phytoplankton productivity, noise, lake drawdown, temporary reduction in benthic fish food organisms, the potential for toxic material release to the overlying water and potential for environmental degradation at the dredged material disposal site. The technique is recommended for deepening and for long range reduction of phosphorus release from sediment. Sediment removal to control toxic materials is possible with minimal environmental impact when proper equipment is used, but it may more than double the cost. Lack of definitive information about rooted plant regrowth rates in dredged areas prohibits explicit recommendations on sediment removal to control plant growth.

Time dependent properties of cohesive sediment relevant to sedimentation management-european experience

Abstract: Field observations show fine sediment suspensions often have a mobile, high-concentration layer adjacent to the sea bed. Stationary suspensions which have time-varying acoustic and mechanical properties develop from these layers. In these circumstances, conventional survey echosounders can not provide unambiguous information on sea bed altitude relevant to safe navigation and optimum dredging practices. In Europe, echosounding is being replaced by in situ density measurement as the means to define navigable depth and to monitor or control dredging. Repeated in situ density surveys allow time series of mass deposition to be constructed, dredging schedules to be optimised, and productivity to be increased. Techniques may then be developed to trap sediment in designated sites where stationary pumping systems remove spoil automatically at an optimum density.

Lake Trehörningen restoration project. Changes in water quality after sediment dredging

Abstract: An increased load of domestic wastewater to Lake Trehorningen induced oxygen-poor water conditions and the development of a reduced sulphide-rich sediment layer. Severely polluted, the lake did not recover, even after advanced wastewater treatment and sewage diversion. Restoration measures with suction dredging and macrophyte elimination were applied in 1975 and 1976. The loose topmost sediment was pumped into an embanked and overgrown bay which was used as a settling pond. The activities also included a restoration of the shorelines. This project is the largest restoration programme carried out in Sweden on a single lake, corresponding to a cost of about US $2 000 000.

A step-wise discriminant analysis of the effects of long term coal mine drainage and coal dredging on phytoplankton of the Guyandotte River

Abstract: Phytoplankton was sampled from the lower 60 miles portion of the Guyandotte River where three active coal dredging operations presently exist and five more permits are pending. Comparisons were made with phytoplankton from a similar stretch of the Mud River, a stream of minimal mine drainage and no coal dredges along its entire course. Diatoms were the predominant planktonic algae on both streams. The number of all phytoplankton species was 24% higher for the Mud River than for the Guyandotte River. Equitability and species diversity indices plus the distribution of mine water indicator algae show that the Guyandotte River is heavily polluted with domestic wastes and mine drainage. No correlation could be established for turbidity, specific conductance, or pH and locations of dredging operations, when the data were analyzed for differences among sampling stations. Step-wise discriminant analysis was used to compare the two streams and the biological, physical, and chemical variables. Based on coefficients for canonical variables, conductivity and pH are the two most influential variables in separating the two streams. Analysis of variance indicates that the canonical means of the stations on the Guyandotte River are significantly different from the Mud River stations.

Environmental mitigation of dredge and fill projects: A case study of coos bay/ north bend, oregon

Abstract: The term “mitigation”; has been used in connection with habitat losses attributable to federal water projects as early as the Rivers and Harbors Act of 1899 and the Fish and Wildlife Coordination Act of 1934. Most of the current requirements to mitigate habitat losses associated with water development projects apply to wetlands, as they are biologically productive and have been destroyed at an increasing rate during recent years by developers seeking prime land in the coastal zone. A case study of the Port of Coos Bay and the City of North Bend, Oregon, provides an actual experience of estuarine mitigation in a dredging project and an airport fill. The case was developed as part of a larger curriculum research study for seaport management. This article is primarily written as a case with a brief introduction and discussion of mitigation requirements, followed by the text of the case and ending with a series of hypotheses for further research.

Benthic community response to dredging borrow pits, Panama City Beach, Florida / by Carl H. Saloman, Steven P. Naughton, and John L. Taylor ; prepared for U.S. Army, Corps of Engineers, Coastal Engineering Research Center.

Abstract: Abstract : This report gives biological and physical oceanographic data from baseline work, and studies of dredged and undredged sediments before and after dredging (9-meter contour) for beach nourishment at Panama City Beach, Florida. These studies were designed to show major short-term environmental effects of offshore dredging and included analyses of hydrology, sediments, and benthos. (Author)

Environmental impact of hydraulic escalator dredging on oyster communities

Abstract: A study to assess the effects of hydraulic escalator dredging on an oyster community was initiated at the request of the Department of Natural Resources, Mary1and Tidewater Fisheries Administration. The purpose of the work was to reevaluate a study done by Manning (1957). A site in the Patuxent River north of Broome Island classified as oyster bottom was selected to conduct an in - situ intensive experiment using the Manning study as a framework for project design. Clams and oysters were present in the study area,although oyster populations were limited in number. (PDFs consists of pp 1-97 and additional Sect II: Middle Bay proposed reclassification sites)

Dredging work by clamshell vacuum pump

Abstract: PURPOSE:To perform excavation and dredging work without lifting a bucket up to the water surface by using a system in which the suction pipe port of a vacuum pump is attached to the inside of the bucket of clamshell. CONSTITUTION:A bucket 2 is opened by operating a clamshell 1 on a base ship 4. Dredging work is performed while sucking up excavated soil and san through a suction pipe port 3 provided inside the bucket 2 by operating a vacuum pump unit 5 provided on the land.

A Survey of the Freshwater Mussels of the Lower Cumberland River from Barkley Dam Tailwater Downstream to the Ohio River.

Abstract: : From 9 September through 8 November, 1981, a survey of freshwater mussels (Mollusca: Bivalvia: Unionidae) was conducted to determine the species, location, relative density and habitat characteristics of mussels inhabiting the Barkley Dam tailwaters Boats, equipped with 16 ft mussel brails, were used to determine the locations and species composition of mussel beds, and scuba divers examined the beds to better sample the mussel fauna and determine sediment characteristics Proposed dredging and disposal sites were examined to estimate the potential impact of Corps' navigation improvement activities upon the mussels Twenty-one species of mussels in 16 general still survive in the lower Cumberland River Mussel beds were found only in stable habitats which have probably been undisturbed for many years and which consist of gravel in a firm sandy-clay Extreme daily fluctuations in discharge through the dam and high silt may have an adverse influence on reproduction and host fish distribution Because the potential impact of dredging operations on downstream mussel beds is not known, it is recommended that a monitoring program be established to evaluate such impact

Distribution of Suspended Sediment in the Patuxent River, Maryland during Dredging Operations for Construction of a Pipeline

Abstract: A trench for emplacement of a natural gas pipeline was excavated by dredging across an estuarine portion of the Patuxent River in southern Maryland. The turbidity of the water was determined by analyzing water samples for total suspended solids before, during and after dredging. The average turbidity during dredging increased a maximum of about two times over its preexisting baseline level. After completion of dredging, turbidity returned to baseline levels in less than three weeks. Estuarine currents in the Patuxent River were not capable of eroding dredge spoil stored in the river itself. These observations indicate that temporary subaqueous storage of spoil during construction in a tidal river can be an environmentally acceptable procedure, with far less potential impact upon the environment than alternatives, such as transportation of spoil off the site for storage or disposal elsewhere.

1981 Student Professional Paper: Engineering Geologic Feasibility of Lignite Mining in Alluvial Valleys by Hydraulic Dredging Methods

Abstract: As much as 4.7 billion tons of an estimated 23.5 billion tons of near surface mineable lignite in Texas lies beneath modern alluvial valley sediments. The shallow groundwater table, flooding, acid water production, and prime agricultural usage will make the floodplain very difficult to mine by conventional surface mining methods. Application of well developed hydraulic dredging techniques to lignite recovery in alluvial valleys may represent an increase in mining economy and a decrease in adverse environmental effects. It is envisioned that a small, portable dredge will utilize the existing hydrologic conditions to mine the floodplain as a supplement to major surface mining operations, and provide an additional 4.7 billion tons of lignite for use.

Dredging work by oil-pressure shovel vacuum pump

Abstract: PURPOSE:To perform excavation and dredging work without lifting the bucket of an oil-pressure shovel up to the water surface by using a system in which the suction pipe of a vacuum pump is attached to the inside of the bucket. CONSTITUTION:A bucket 2 is wound and retreated by the operation of an oil- pressure shovel 1. Dredging work is performed while sucking up excavated soil and sand through a suction pipe port 3 inside the bucket 2 by operating a vacuum pump unit 4.

Sediment Management for Southern California Mountians, Coastal Plains and Shoreline. Part D: Special Inland Studies

Abstract: In southern California the natural environmental system involves the continual relocation of sedimentary materials. Particles are eroded from inland areas where there is sufficient relief and, precipitation. Then, with reductions in hydraulic gradient along the stream course and at the shoreline, the velocity of surface runoff is reduced and there is deposition. Generally, coarse sand, gravel and larger particles are deposited near the base of the eroding surfaces (mountains and hills) and the finer sediments are deposited on floodplains, in bays or lagoons, and at the shoreline as delta deposits. Very fine silt and clay particles, which make up a significant part of the eroded material, are carried offshore where they eventually deposit in deeper areas. Sand deposited at the shoreline is gradually moved along the coast by waves and currents, and provides nourishment for local beaches. However, eventually much of this littoral material is also lost to offshore areas. Human developments in the coastal region have substantially altered the natural sedimentary processes, through changes in land use, the harvesting of natural resources (logging, grazing, and sand and gravel mining); the construction and operation of water conservation facilities and flood control structures; and coastal developments. In almost all cases these developments have grown out of recognized needs and have well served their primary purpose. At the time possible deleterious effects on the local or regional sediment balance were generally unforeseen or were felt to be of secondary importance. In 1975 a large-scale study of inland and coastal sedimentation processes in southern California was initiated by the Environmental Quality Laboratory at the California Institute of Technology and the Center for Coastal Studies at Scripps Institution of Oceanography. This volume is one of a series of reports from this study. Using existing data bases, this series attempts to define quantitatively inland and coastal sedimentation processes and identify the effects man has had on these processes. To resolve some issues related to long-term sediment management, additional research and data will be needed. In the series there are four Caltech reports that provide supporting studies for the summary report (EQL Report No. 17). These reports include: EQL Report 17-A Regional Geological History EQL Report 17-B Inland Sediment Movements by Natural Processes EQL Report 17-C Coastal Sediment Delivery by Major Rivers in Southern California EQL Report 17-D -- Special Inland Studies Additional supporting reports on coastal studies (shoreline sedimentation processes, control structures, dredging, etc.) are being published by the Center for Coastal Studies at Scripps Institution of Oceanography, La Jolla, California.

Field Dredging Test of Soft Mud Layer by a Front-Open Type Drag Head,

Abstract: : This paper describes the result of a field dredging test carried out as part of a study of a method of effective removal and disposal of bottom sediments in a vast closed water area such as Tokyo Bay. We manufactured a new type drag head that can dredge soft mud, dredging thinly and widely, in high density. We equipped a trailing hopper suction dredge (hopper capacity of 4000 cu m) with thisnew drag head and field tested off China in Tokyo Bay. Good results were obtained.

Biological Survey, Buffalo River and Outer Harbor of Buffalo, New York. Volume I.

Abstract: : The U.S. Army Corps of Engineers is considering the feasibility of dredging the Outer Harbor and Buffalo River channels deeper to accomodate deeper draft vessels and/or to construct alternative means of trans-shipment of raw materials. An intensive study of the Buffalo River, Ship Canal and Outer Harbor of Buffalo, New York, was undertaken between April 1981 and May 1982 with the following general objectives: evaluate existing conditions in the river and harbor and to evaluate the biological impact of dredging the existing channel deeper in the Buffalo River and Outer Harbor; evaluate the biological impact of alternative proposals to dredging such as transshipment of raw materials by conveyor; evaluate the biological impact of removal of debris, old pilings, etc. along the Buffalo shoreline; evaluate existing conditions in potential disposal areas (Fig.2) and to evaluate the biological impact of spoil disposal in these areas; and provide a functional assessment of the ecological components studied and evaluate their significance with and without project implementation to the area ecosystem. In Volume 1, the Final Report, our analysis and interpretation of existing conditions and our assessment of impacts are presented. In Volume 2, the Data Report, the raw field data is presented in tabular form.

Finite Element Modelling of Sediment Transport in an Estuary

Abstract: Shallow waters with intertidal flats and gradual changes of bathymetry due to sedimentation and erosion processes are some of the main characteristics of the German north sea coast. Owing to the morphological instability in many areas, extensive dredging work is necessary to maintain navigation channels in both the coastal zone and in tidal rivers. Attempts to obtain a better insight into the sediment transport processes in these areas have been made in the past, and include field observations and investigations using movable-bed hydraulic models. Due to the considerable expense of field-investigations and problems of hydraulic scaling in physical models, the latter methods are gradually being supplemented by numerical methods.

Removal of Bottom Sediments in Osaka Port by the Pneuma Pump Dredge 'Shunkai',

Abstract: : Osaka Port has been suffering from mud sediments polluted with organic substances on the bottom of rivers due to wastewater from factories and city sewage. The Authority of Osaka City, having noticed the excellent performance of the Pneuma pump system, undertook the first mud dredging experiment in Japan with that system (which was introduced in Dec. 1971). Through this experimental dredging, the suitability of the Pneuma pump system to the dredging of polluted mud was well proved. A dredging squadron with hopper barges that had undergone the necessary modifications was organized. The squadron has engaged in dredging operations of polluted mud since Nov. 74 to the present.

Proceedings of a Seminar on Attaining Water Quality Goals through Water Management Procedures, 17-18 February 1982, Dallas, Texas,

Abstract: : Contents: The Committee on Water Quality, Evaluation of Water Quality Impacts from Water Resources Management Programs and Project, Water Quality Program Management, Environmental and Water Quality Operational Studies (EWQOS) - Status, Reservoir Water Quality Data Collection, Water Quality Laboratory Analysis, Water Quality Data Management, Water Quality Data Interpretation, Sampling Design - A Necessary First Step to Data Collection, Laboratory Analyses, Application of Database Management Techniques to Reservoir Water Quality Studies, Water Quality Data Interpretation - Laboratory Response, River and Reservoir Systems Water Quality Modeling Capability, One and Two Dimensional Water Quality Modeling, District Considerations in Math Modeling, Water Control Strategies, Water Control Operating Constraints, Water Control and Environmental Objectives, An Update on Dredging Activities in the Pacific Northwest, The Experience of the St. Paul District, Corps of Engineers with State Coordination of Dredging Activities, Disposal of Highly Contaminated Dredged Material, Ocean Dumping of Dredge Material off the Louisiana Coast, O/M Dredging Experience as Related to Channel Deepening for Coal Ports, Dension Management Releases, Mount St. Helens Recovery Operation, Analyzing Salinity Response in San Francisco Bay, Turbine Venting at Clarks Hill Dam, and Water Quality Management at Harry S. Truman Dam and Reservoir.

Grays Harbor and Chehalis River Improvements to Navigation Environmental Studies. Wildlife Studies at Proposed Disposal Sites in Grays Harbor, Washington,

Abstract: : A 15-month study to inventory wildlife resources on 4 proposed terrestrial dredged material disposal sties and 1 intertidal disposal site was initiated. Major emphasis was placed on inventorying birds and mammals to assess the value of these areas to wildlife. Amphibians, reptiles, and plants received less emphasis. Seven species of amphibians and 3 species of reptiles were captured on fill sites 16, 17, and 18 during this study. The spotted frog and Dunn's salamander have been reported only rarely in Grays Harbor County. Most individuals of these two groups of animals would be killed by disposal of dredge materials on these sites. At least 46 species of waterbirds use the main channel and sloughs proximal to the Cosmopolis Reach of the Chehalis River. Mallards and scaup were the most common waterfowl; highest numbers were seen during winter. Areas preferred by waterfowl were river marshes and upper reaches of sloughs. Large numbers (more than 200) of western grebes, gulls and diving waterfowl used the Cosmopolis Reach during all seasons. During dredging, direct impacts to waterfowl and bald eagles would be negligible; most observations were 5 kms or more upstream from proposed dredging activity. Impacts (i.e. decreased hunting success due to suspended particulates) to diving birds would be minimized by dredging between August and October, when numbers of birds are lowest. Dredging during ebb tides would result in sediments disturbed by dredging flowing into the harbor.

Sedimentation, dredging, and spoil disposal in a subtropical estuarine lagoon

Abstract: Kaneohe Bay, Hawaii, is an estuary used as a harbor for a military installation and for recreation, fishing, and research purposes. Rapid shoaling of the bay had been reported and attributed to increased stream erosion and sedimentation from the newly suburbanized watershed. Comparison of a 1976 bathymetric survey of Kaneohe Bay with that of a 1927 survey indicates an average shoaling of the lagoonal area of 1.0 m. Average shoaling for the north and middle bay at 0.6m/49 years (1.2 cm yr−1 is lower than for the south bay at 1.5m/49 years (3.1 cm yr−1). The total lagoonal fill in the 49-year period is about 1.95× 107 m3, assigned as follows: 64% carbonate detritus from the reefs as well as growth of living coral and unrecorded dredging spill, 9% recorded dredging spoils, and only 27% terrigenous sediment. Seismic reflection profiles distinguish spoil from natural sediment and show that the infilling sediment is trapped between, burying reef structures built during Quaternary lower stands of the sea. There had been little obvious change between 1882 and 1927 surveys. All information suggests that increased shoaling rates since 1927 are due to reported and unreported disposal of dredge spoil, mainly from 1939 to 1945 for ship and seaplane channels in the south bay, and not from increased runoff and urbanization around the south bay.

Sediment problems and their control in u.s. navy pier slips in selected harbors of the united states

Abstract: United States Navy pier slips in the harbors of Hampton Roads, VA; Charleston, SC; Mayport, FL; and Alameda, CA experience sedimentation problems. This affects berthing of deep-draft vessels such as aircraft carriers where depths of water up to 45 ft (13.7 m) are required. In addition to problems involving grounding and clogging of cooling water systems, both of which render a vessel inoperative, increasing cost of dredging maintenance is encountered. Various means of sediment control in pier slips are discussed. These include the use of single row of water jets, water jet arrays, silt curtains, agitation dredging, and a sand crater-eductor method.

Dredging to minimize wave penetration into a harbour

Abstract: Wave protection within a new harbour development has been achieved by shaped dredging in place of long breakwaters. The dredging shape was initially established through wave refraction calculations and then confirmed and optimized in a physical three dimensional model. The cost of additional dredging for the specified shape was A$100,000 compared to estimated breakwater costs of A$l,000,000.

Overview of Corps Research Program Dredging Contaminated Sediments

Abstract: : This paper outlines active research at the Waterways Experiment Station on equipment and techniques for dredging contaminated sediments. The question is being addressed in three ways: the assembly and evaluation of available domestic and foreign information concerning sediment resuspension and contaminant release; the development of appropriate laboratory tests to predict contaminant release from resuspended sediments; and the use of field studies to monitor performance and compare dredges operating under various conditions. Plans are discussed for evaluating existing dredging equipment to determine best techniques for dredging sediments that are highly contaminated with toxic substances. Initial field studies have already been completed on evaluating sediment resuspension at the point of dredging for cutterhead, dustpan, and clamshell dredges. The results of these preliminary studies are discussed.

Bottom Sediment Dredge 'Clean Up' - Principle and Results,

Abstract: : Topics include: Secondary water pollution; New equipment for sediment dredging; Turbidity.

Literatuuronderzoek naar de mogelijke gevolgen van zandwinning in de Waddenzee

Abstract: This report describes the results of a literature review about the possible ecological effects of dredging in the Wadden Sea by Rijkswaterstaat order. Formulated are the possible ecological effects of dredging in the Wadden Sea and the chance that these effects will occur during dredging activities. The basis information of this report is formed by literature about dredging and about the Wadden Sea, and by the results of some measurements of a dredging activity in 1977 in a tidal channel (Blauwe Slenk) .The effects of dredging can be subdivided in effects on the water quality, effects on the sediment load of the water and effects on the bottom fauna. In addition some remarks are made about the possible effects on birds and seals. This review summarizes the literature till June 1978.

Engineering geologic feasibility of lignite mining in alluvial valleys by hydraulic dredging methods

Abstract: As much as 4.7 billion tons of an estimated 23.5 billion tons of near surface mineable lignite in Texas lies beneath modern alluvial valley sediments. The shallow groundwater table, flooding, acid water production, and prime agricultural usage will make the floodplain very difficult to mine by conventional surface mining methods. Application of well developed hydraulic dredging techniques to lignite recovery in alluvial valleys may represent an increase in mining economy and a decrease in adverse environmental effects. It is envisioned that a small, portable dredge will utilize the existing hydrologic conditions to mine the floodplain as a supplement to major surface mining operations, and provide an additional 4.7 billion tons of lignite for use. 4 refs.