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DREDGING PROCESS AND ITS EFFECT PRESENTED BY INDRANIL BANERJEE ROLL NUMBER- 001930301008 DEPARTMENT OF WATER RESOURCES ENGINEERING JADAVPUR UNIVERSITY 2 ND SEMESTER, SPRING 2020
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CONTENTS INTRODUCTION NECESSITY TYPE OF DREDGER MECHANICAL DREDGERS BUCKET LADDER DREDGER GRAB DREDGER BACKHOE DREDGER HYDRALIC DREDGERS SUCTION HOPER DREDGER CUTTER SUCTION DREDGER TRAILING SUCTION HOPPER DREDGER SITE INVESTIGATION VERIOUS SURVEYING CASSIFICATION OF SOILS DREDGER SELECTION DUMPING GROUNDS FIELD SURVEY EFFECTIVENESS IMPACT OPERATION AND MAINTENANCE STATUS ENVIRONMENTAL EFFECT OF DREDGING CONCLUSION REFERENCES
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INTRODUCTION it is the subaqueous or underwater excavation of soils and rock. The process consists of four phases: Excavation Vertical transport Horizontal transport Placement or use of the material dredged. A dredgers is a piece of equipment which can dig, transport and dump a certain amount of under water laying soil in a certain time. The quantity of soil moved per unit of time is called Production.
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NECESSITY to create a new harbor, berth or waterway, dredging is to be done mandatory Sea bed mining is also an important part where dredging is being done affected by chemical spills underwater foundation works for bridge piers requires dredging to be carried out. To maintain navigable waterways, Construction and Reclamation Beach nourishment Environmental remediation Flood control Mining
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TYPES OF DREDGER Depending upon the method used to transport loosened material from the sea- bed to the surface they may be classified as: a) Mechanical dredgers b) Hydraulic dredgers c) Other types Mechanical dredgers Hydraulic dredgers
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MECHANICAL DREDGERS. a) Bucket ladder dredger b) Grab dredger c) Backhoe/dipper dredger
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BUCKET LADDER DREDGER
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WORKING METHOD
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BUCKET LADDER DREDGER PARAMETER
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GRAB DREDGER
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VARIOUS TYPE OF GRAB
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BACKHOE DREDGER
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HYDRAULIC DREDGERS a) Profile or plain suction dredger 1.Barge Loading suction dredger 2.Standard plain suction dredger 3.Deep suction dredger b) Cutter suction dredger c) Trailing suction hopper dredger
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SUCTION HOPER DREDGER
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CUTTER SUCTION DREDGER
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TRAILING SUCTION HOPPER DREDGER
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SITE INVESTIGATION 1. Characterization of the material to be dredged 2. Determination of the total volume to be dredged 3. Topographic Survey for shore controls land areas reclamation 4. The hydrographic of the dredging and disposal locations 5. Bathymetric surveys to determine bed levels 6. Geotechnical investigations to assess the nature of the material 7. Geo-physical investigations 8. Environmental surveys_Geo-physical investigations Meteorological Oceanographic
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Topographic Survey Bathymetric surveysTopographic Survey Multi Beam Echo Sounder survey single Beam Echo Sounder survey Magnetometer Surveys VERIOUS SURVEY IMAGE
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CASSIFICATION OF SOILS In order to form an opinion as to the most suitable equipment for dredging under water, and to estimate performance of dredging equipment, it is vital to know the nature, location, transportation and disposal quantities of materials to be dredged. The soil classifications as per Indian Standards.
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DREDGER SELECTION ideal dredge varies between dredging projects. Dredge selection depends on availability and cost, and various physical characteristics
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DUMPING GROUNDS The effects of the disposal of such wastes include the physical blanketing of the bottom. In addition, these spoils may be contaminated with heavy metals, oil, or oreganos chlorine compounds, causing adverse effects on fish populations and marine biology.
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TUTICORIN PORT DREDGING PROJECT Field Survey: August 2003 Objectives The project’s objectives were to alleviate draught *3 restrictions by dredging port water and approach channels at Tuticorin Port in southern Tamil Nadu, and to improve the efficiency of port operations by increasing per vessel payload, and thereby contribute to economic growth in the state. Outputs The outputs of this project were as follows: 1) Dredging of approach channel · Dredged sand volume: 580K m 3 · Channel length: 2.7km (currently 1.4km) · Channel width: 183m (virtually identical to current width) · Design water depth: 12.5m (currently 10.2-11.4m) 2) Dredging of harbor basin · Dredged sand volume: 1.22m m 3 · Diameter of basin: 688m Dredging to increase water depth of zones fronting individual berths (Berth VII, etc.) · Design water depth: 11.9m (current depth of basin: 10.6m; current depth of other frontal water zones: 9.5m-11.3m) 3) Vessel types targeted · Bulk (dry) cargo vessels: length 230m × width 32.5m × draught 10.7m · Bulk (liquid) cargo vessels: length 235m × width 32.5m × draught 10.7m · Container vessels: length 220m × width 30.0m × draught 10.7m 4) Civil engineering works · Dredger model: Cutter suction dredger · Dredge sand disposal: to be dumped in two dumping grounds within port precincts Shore protection of areas peripheral to the dumping grounds · Other works: greening/planting port areas
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EFFECTIVENESS Changes in Cargo Handling Volumes, etc. Indices relating to the operational efficiency of the port prior to and after the implementation of the project (shaded sections represent the actual implementation period) are as shown below
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Impact Initially Projected Impacts- port carriers have become more active. Environmental Impacts - A report was obtained via the fishery company also contains no adverse impacts on the fishery industry. Other Socioeconomic Impacts (effects on local residents) Other Impacts the volume of trade – increased rapidly from 59 thousand tons in fiscal 1999 to 326 thousand tons in fiscal 2001 (i.e. an increase of approximately 5.5 times), since larger vessels can be used now because of the dredging work.
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Operation and Maintenance Status 1.Tuticorin Port receives physiographic protection from Sri Lanka, and because of its structure, accumulation of sand due to tides and winds is difficult, and (2) the bedrock on the ocean floor is very hard and this is not a river port. Therefore dredging is not generating any maintenance costs. To summarize the above, the project succeeded in securing the planned water depths in the approach channel and harbor basin, and the port is functioning as expected. Moreover, no maintenance costs are being generated since no special work is necessary to maintain the water depth thanks to the port’s geographical advantages. The executing agency is not facing any particular problems either organizationally or financially, and the overall sustainability of the project is deemed to be high.
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ENVIRONMENTAL EFFECT OF DREDGING Development projects have some common problems related to the environment. The primary categories can be summarized as being__ Water-Related Effects(sattlement,blasting,altered bathymetry, changing shoreline Land-Related Effects(dust and other airborne emissions) Air-Related Effects(especially hydrogen sulphides) Placement of Dredged Material(Material contamination) Socio-cultural Effects(work practices, site selection)
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CONCLUSION it can be stated that every type of dredger has its own applied working area in which its production is optimal in a technical way as well as in an economical way. It will be clear that the boundaries of these applied working areas are not strictly determined, but are also determined by other working conditions, which can differ from lob to job. In order to accomplish dredging process,different survey, dredger selection, and environmental impact need to be calculated, through the proper dredger selection.
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REFERENCES 1.>http://sagarmala.gov.in/sites/default/files/dredgeguidelinesAugust2016-30146365.pdfhttp://sagarmala.gov.in/sites/default/files/dredgeguidelinesAugust2016-30146365.pdf 2.>https://www.jandenul.com/sites/default/files/activity-category/brochures/Dredging_and_Marine_Works.pdfhttps://www.jandenul.com/sites/default/files/activity-category/brochures/Dredging_and_Marine_Works.pdf 3.>https://www.damen.com/-/media/Products/Images/Clusters- groups/Dredging/Documents/Brochure_Damen_Dredging.pdfhttps://www.damen.com/-/media/Products/Images/Clusters- groups/Dredging/Documents/Brochure_Damen_Dredging.pdf 4.>https://www.researchgate.net/publication/271443986_Dredging_Processes_The_Loading_Process_of_a_Traili ng_Suction_Hopper_Dredge_Lecture_Noteshttps://www.researchgate.net/publication/271443986_Dredging_Processes_The_Loading_Process_of_a_Traili ng_Suction_Hopper_Dredge_Lecture_Notes 5.>https://www.engr.colostate.edu/~pierre/ce_old/classes/ce717/2_OverviewofDredgingandDMD_Welp.pdfhttps://www.engr.colostate.edu/~pierre/ce_old/classes/ce717/2_OverviewofDredgingandDMD_Welp.pdf 6.>https://www.epa.vic.gov.au/~/media/Publications/691.pdfhttps://www.epa.vic.gov.au/~/media/Publications/691.pdf 7.> http://bit.ly/2XTuGoqhttp://bit.ly/2XTuGoq 8.> http://www.fao.org/docrep/013/i1883e/i1883e06.pdfhttp://www.fao.org/docrep/013/i1883e/i1883e06.pdf 9.> https://nptel.ac.in/courses/114106035/https://nptel.ac.in/courses/114106035/ 10.> http://www.imcbrokers.com/blog/overview/detail/types-of-dredgershttp://www.imcbrokers.com/blog/overview/detail/types-of-dredgers 11.> https://dredging.org/documents/ceda/downloads/vlasblom1-introduction-to-dredging-equipment.pdfhttps://dredging.org/documents/ceda/downloads/vlasblom1-introduction-to-dredging-equipment.pdf
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THANK YOU
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