• Journal of Environmental Impact Assessment
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• v.18 no.3
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• pp.185-193
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• 2009

This study documented and diagnosed the status and problems of coastal dredging and offshore disposal of dredged sediments in South Korea to improve assessment procedures for marine environmental impacts and develop effective management systems. A total of $729({\times}10^6)m^3$ of coastal sediment was dredged in the harbors during the period of 2001-2008. Most of dredged sediment was disposed to the land dumping sites whereas ocean disposal accounted for less than 5%. Ocean disposal areas were especially concentrated to the exclusive economic zone (EEZ) in the southeast of Busan, which is not only an important fishing area for fishermen, but also considered to be spawning and nursery ground for some commercial fish species. To minimize negative impacts of dredging and ocean disposal of coastal sediment on marine ecosystem and potential strife among coastal users, we suggest 1) in development projects involving ocean disposal, it should be mandatory to propose careful reuse plans in the land, and 2) guidelines of environmental assessment and consequence management programs should be developed and implemented.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.281-287
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• 2009

In this study, the behavior of breasting dolphin caused by the maximum wave height in the coastal area of Incheon has been investigated. The dynamic deflection, shear stress and moment of pile are analyzed using the coefficient of horizontal subgrade reaction resulted from loading tests for different DWT (Dead Weight Tonnage). The dynamic characteristics of pile in accumulated and dredged soils show almost the same pattern. It is shown that the resistance of dolphin to external load increases as the diameter of pile increases. The bettered pile dolphin is more than 10 times stable than the vertical pile type based on the study of dynamic characteristics of dolphin.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.345-354
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• 2009

The review of statements and coastal development characteristics in South Korea were diagnosed by the consultation on the coastal area utilization in Korea. The occupation and the use of public water were dominated by installation of coastal structure and seawater supply and drainage whereas the reclamation areas were predominantly utilized for developing industrial complex, harbor, fishing port and road. The occupation and the use were dominant in western coast, but reclamation was dominant in southern coast of Korea. The number of utilization cases was particularly greater in Jeonnam, Gyeongnam, and Gyeonggi Province including Incheon. The number of the statements reviews increased by more than 200 cases in 2008 compared with 2007, and most of them were the simple statements. The statements related to ocean disposal of dredged sediment, reclamation, dredging sediment, seawater supply and drainage, and marine sand mining were submitted for review. Coastal utilization was especially active in the regions of seawater quality criteria I and II. In particular, special management sea areas designated under the relevant marine regulations were utilized mostly by reclamation for developing harbor, fishing port and coastal structure. Development activities in national parks comprised primarily structure installation and coastal maintenance. In the fisheries resources protection areas, 40% of the total cases accounted for coastal maintenance, 31% for structure installation, and 16% for seawater supply and drainage. In addition, alternative plans for the improvement in policies and system of marine environmental impact assessment were suggested to enhance the function and confidence of the consultation on the coastal area utilization in Korea.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.57-66
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• 2013

Although the quantity of dredged soils has increased owing to recent new harbor construction, sea course management, polluted sediment dredging, and four-river project, the reuse or recycling of those dredged soils has not done properly in Korea. To develop measures to utilize them in various ways for reuse or recycling, the biophysicochemical properties of dredged soils and sediment were assessed in this study. Samples were classified according to their sources-river and sea-by location, and as dredged soil and sediment depending on storage time. The results showed that dredged materials from the sea have high clay content and can be used for making bricks, tiles, and lightweight backfill materials, while dredged materials from the river have high sand content and can be used in sand aggregates. Separation procedures, depending on the intended application, should be carried out because all dredged materials are poorly sorted. All dredged soils and sediments have high salinity, and hence, salts should be removed before use for cultivation. Since dredged materials from the sea have adequate concentrations of nutrients, except phosphate, they can be used for creating and restoring coastal habitats without carrying out any additional removal processes. The high overall microbial activities in dredged materials from the river suggested that active degradation of organic matter, circulation of nutrients, and provision of nutrients may occur if these dredged materials are used for cultivation purpose.

• Journal of Environmental Impact Assessment
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• v.18 no.3
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• pp.131-141
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• 2009

We studied improvement in marine environmental impact assessment and related management systems of coastal sediments that are dredged inshore but disposed offshore. After reviewing and diagnosing the existing assessment procedures and problems, we recommend to design the core assessment items and improve the reliability of assessment byenhancing the quality assurance/quality control (QA/QC) and verification processes. We proposed eco-friendly disposal plan for dredging sediment such as reuse system in land development was explored. A marine environmental database system was established to support the assessment processes. Guidelines for marine research and modelling were proposed for improving assessment of dredging and disposal of coastal sediment. Also, applying of screening and scoping for marine environmental assessment was reviewed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.119-128
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• 2013

Since the early 2000s, demand for coastal dredging projects have been significantly increased, and the dredged sediments have showed the continuing marked increases through the multiple projects with other coastal development and constructions. As significant or potential degradation of marine environment has been mounting, we checked the current situation of marine environmental impact assessment through marine water and sediment qualities in relation with dredging projects of the sea area utilization consultation statements submitted in 2011. While analysis percentages of the general items were usually higher, harmful components such as metals revealed wide variation of analysis percentages. In the event of analysis of metals, the pre-treatment process (full digestion) and analysis method were not properly implemented in accordance with the guidelines for preparation of consultation statements. Although not specified in the guidelines, verification procedures (tests of recovery efficiency and detection limit) to secure the reliability were almost ignored. As a result, most of developers did conduct poor marine environmental impact assessment on coastal dredging and related projects. We suggested that the responsible government authority should establish new detailed guidelines on the sea area utilization consultation for more strict evaluation and diagnosis of marine environment and distinctly request the developer to obey the guidelines by complementing the system of the sea area utilization consultation.

• Journal of Coastal Disaster Prevention
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• v.5 no.4
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• pp.163-172
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• 2018

To propose the design technique and the execution manual of the LWFS(Lightweight Foamed Soil) method using dredged soil, the operation system for the test-bed integrated management, and to establish an amendment for the domestic quantity per unit and specifications, and a strategy for its internationalization. In order to utilize the dredged soil from the coastal area as a construction material, we constructed the embankment with LWFS on soft ground and monitored its behavior. As a result, it can be expected that the use of LWFS as an embankment material on the soft ground can improve the economic efficiency by reducing the depth and period of soil improvement as well as the uses of nearby dredged soil. To verify the utilization of the dredged soil as a material for light-weighted roadbed, soft ground and foundation ground, and surface processing, perform an experimental construction for practical structures and analyze the behavior. It is expected to be able to improve the soft ground with dredged soil and develop technique codes and manuals of the dredged soil reclamation by constructing a test-bed in the same size of the fields, and establish the criteria and manual of effective dredged soil reclamation for practical use. The application technology of the dredged soil reclamation during harbor constructions and dredged soil reclamation constructions can be reflected during the working design stage. By using the materials immediately that occur from the reclamation during harbor and background land developments, the development time will decrease and an increase of economic feasibility will happen. It is expected to be able to apply the improved soil at dredged soil reclamation, harbor and shore protection construction, dredged soil purification projects etc. Future-work for develop the design criteria and guideline for the technology of field application of dredged soil reclamation is that review the proposed test-bed sites, consult with the institutions relevant with the test-bed, establish the space planning of the test-bed, licensing from the institutions relevant with the test-bed, select a test-bed for the dredged soil disposal area.

• Journal of Coastal Disaster Prevention
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• v.5 no.4
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• pp.173-182
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• 2018

As the research about increasing the efficiency of dredging soil transport, the technology, which reduce the friction between pipe wall and fluid in the pipe and disturbed generating pipe blockage, has been developed. So for the purpose of applying this technology to real construction site, main test has been tried at the real scale test in field. As a test result, this paper will show 30% flow efficiency increasing by permitted electro magnetic force to the pipe. And test result was evaluated as a ultra sonic velocity profiler. To propose the design technique and the execution manual of the high efficiency dredging material transport technic, this research have confirmed flow status changing depending on a soil material kind under electro-magnetic field and analyze the effect of electro-magnetic field which affects to each dredged soil material transportation. For achieving this research, EMF(Electro-Magnetic Field) generator is installed on the dredger(20,000HP) and through monitored flow status, dredging soil flow rate and sampled material specification is confirmed. Also dredger operating condition is measured and dredger power for soil transportation, hydraulic gradient and flow rate are compared, as transportation efficiency is calculated by this parameter, it is possible to check transportation efficiency improvement depending on each dredged soil material under electro-magnetic field. To verify the technique of dredged soil transfer using electromagnetic field, which is the core technique of the high efficiency dredged soil transfer, and the technique of expert system for pipeline transfer and the flow state. This could lead to a verification of transfer efficiency according to the characteristics of the dredged soil (sand, clay, silt) and the transfer distance (5km, 10km, 15km), which is planned to be used for a technology development of pump power reduction and long-distance transfer applying the high efficiency dredged soil transfer technology.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.374-381
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• 2015

Occurrences of coastal dredged materials are ever increasing due to port construction, navigational course maintenance and dredging of polluted coastal sediments. Ocean dumping of the coastal dredged materials has become virtually prohibited as London Treaty will be enacted as of the year 2012. It will be necessary to treat and recycle the dredged materials that may carry organic pollutants and heavy metals in a reasonable and effective process: collection of the dredged materials, liquid and solid separation, and treatment of organic compounds and heavy metals. In this study we have developed a continuous bioreactor system that can treat a mixture of silt and particulate organic matter using a microbial consortium (BM-S-1). The steady-state operation conditions were: pH (7.4-7.5), temperature ($16^{\circ}C$), DO (7.5-7.9), and salt concentration (3.4-3.7%). The treatment efficiencies of SCOD, T-N and T-P of the mixture were 95-96%, 92-99%, and 79-97%. The system was also effective in removal of heavy metals such as Zn, Ni, and Cr. Levels of MLSS during three months operation period were 11,000-19,000 mg/L. Interestingly, there was little sludge generated during this period of operation. The augmented microbial consortium seemed to be quite active in the removal of the organic component (30%) present in the dredged material in association with indigenous bacteria. The dominant phyla in the treatment processes were Proteobacteria and Bacteroidetes while dominant genii were Marinobacterium, Flaviramulus, Formosa, Alteromonadaceae_uc, Flavobacteriaceae_uc. These results will contribute to a development of a successful bioremediation technology for various coastal and river sediments with a high content of organic matter, inorganic nutrients and heavy metals, leading to a successful reuse of the polluted dredged sediments.