Environmental Reliability for Sustainable Dredging
1.???????? Introduction
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Dredging is process of digging under water for purpose to maintain the depth in navigation channels. Dredging is required to develop and maintain navigation infrastructure, reclamation, maintenance of river flow, beach nourishment, and environmental remediation of contaminated sediments. Study on environmental impact of dredging is not new and recently there is concerned about balance between the need to dredge, economic viability, social technical acceptance and adequate environmental protection can be challenge. Various methods has been implemented for management of dredging activities, but select in the best practice approach is also a bog challenge that require high level of understanding of the technical and economical aspects of the dredging process. input from ecological experts and dredging specialists. Community participation from port authorities, regulatory agencies, the dredging industry and non-governmental organisations such as environmentalists and private sector consultancies.
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.2. The Need for and dredging requirement
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Dredging is the excavation, elevating heaving and transport of underwater sediments and soils for the construction and livelihood of ports and waterways, dikes and other infrastructures, for reclamation, conservation of river flow, shore nutrition, to extract mineral resources, especially sand and gravel, for use case in point in the construction industry, and for the environmental remediation of contaminated sediments.
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Globally, many hundreds of millions of cubic meters (m3) of sediments are dredged annually, with most of this volume being handled in coastal areas. A part of this aggregate represents chief dredging which involves the excavation of sediments to establish ports, asylums, and navigable waterways. Maintenance dredging sustains sufficient water depths for secure navigation by periodic removal of sediment amassed due to normal and human-induced sedimentation. Maintenance dredging may vary from an about consecutive activity throughout the year to an rare play happening merely once every few years. Dredging activities attempt social, economic and environmental benefits to the entire community. Hydrography chart and bathymetric map are used as guidance to vision of discrete bottom of water. Vigilant is requiring for the base as the, they are proned to sudden change leading to shoaling due to flood or drought. Survey of a navigation channel? to situate dredging area? done through? drawing of? isolines, or lines interlocking points of equal depth, on the map so that captains and ships' pilots can obtain an idea of the "mounds and valleys" underwater [1,3].
???Dredge material:Dredging is necessary to preserve waterways channel. Nearly 400 million cubic yards of material is dredged every year. Consequently,
asics tiger, approximately 400 million cubic yards of material must be placed in approved elimination sites or another used for another environmentally acceptable intention.? Sustainable elimination of dredge material is very imperative as it ends up saving a lot of money and maintains reliability and efficiency use of resources advantage of sustainable beneficial disposal are [2,3]:
Cost saving on money spent on finding and administrate disposal sites. It avoids habitat and ecological impacts that disposal may cause. It saves capacity in existing disposal sites. It can be a low-cost alternative to purchasing priceless fill for construction projects.It can be used to enhance or reinstate habitat.
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3. Environmental requirement of dredging project
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The tendering of a dredging contract typically occurs later a full engineering design has been completed (i.e. later the planning and design phase). However, for other types of contracting mechanisms (e.g., design-build), the tendering of contract may occur early in the overall project process, accordingly requiring the Contractor to perform many of the evaluation and design go himself. Table 1 shows phases of dredging project and the risk control components.
?The planning and design phase begins with defining overall functional requirements to meet the project objectives. This involves evaluating potential environmental impacts and any regulatory limitations,
discount asics shoes, and concludes with preparing projects specifications. The planning and design phase is used to identify risk areas and risk control option in advance to assist protect the environment during dredging, transport, and disposal activities and? subsequent monitoring and possible remedial actions. Elements of project formulation include:
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Functional RequirementsConceptual DesignRegulatory FrameworkBaseline EnvironmentStakeholder InputPotential impact Review the baseline condition as a consequence of construction and post-project activities. Environmental Impact Assessment (EIA) Risk control optionPrepare Final Project Design and Specifications
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Afinal chart addresses all major factors of the project: engineering chart, environmental treatment, construction sequencing, and construction management. The specification's level of detail ambition depend on the type of compact, thecomplexity of the project, and the experience with dredging of both the project proponent and contractor(s). Additional environmental reiterate may be necessitated to build that whichever residual risk, alternatively actual clash, namely befitting Risk control alternative have to be based on a clear elucidation of the project's technical and regulatory requirements. Studies behaved during the EIA or project planning, for well for information from regulators and stakeholders can contribute technical message for advised risk control option including [3,4] :?
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Sediment characterization (e.g., grain size distribution, level of contamination, etc.)?Bathymetric/topographic surveys with design profiles, which establishes the volume of sediment to be dredged;?An understanding of hydraulic/hydrodynamic/oceanographic conditions that may impede operations;?The destination or final use of the dredged material, including placement options and locations;?The environmental functions and value of the area to be dredged, establishing environmental boundary conditions;?The environmental value of dredged material management areas (e.g., placement in confined or unconfined areas, or beneficial use options);?Existing site uses (e.g., navigation, recreational use, commercial fishing, quality of life impacts [air, ruckus, light]) to establish reasonable operational measures;?Legal conditions.
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Environmental appearances related to future use and maintenance of the project's post construction condition should consider the areas of facility operations, future maintenance, long-term monitoring. During the construction phase, the contractor assumes basic duty for conference the requirements of the project specifications, including meeting permit and contractual environmental conditions and implementation of risk control options. Major steps in the construction phase include:
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Tendering and Contract AwardContractor Defines Construction-Methods and Selects Equipment Project Execution: Risk control option should based on best practice
Figure 2a? shows example of post dredging impact in Kuala Terengganu
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Figure 2a Post dredging impact in Kuala Terengganu
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5.0 Environmental risk requirements of dredging project
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Risk analysis in a dredging project, including taking into account adherence to the Precautionary Principle. It involves methods for assessing the significance of the likely impacts and essential environmental characteristics that require consideration during both the planning and implementation phases and the mechanisms whereby impacts can occur.
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5.1 Qualitative based environmental impact assessment
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Understanding the environments in which dredging and dredged material placement occur is a necessity of discreet decision making for environmental conservation. A thorough knowledge of baseline conditions is needed so that a dredging project's environmental effects can be assessed properly and monitored against an admitted baseline. The baseline data must address natural variations, seasonal patterns and longer term trends to invest a context for determining whether a change is the result of dredging or not. As a minimum, characterization of the potentially affected environment should consist of recent surveys (performed among the final three years) and studies of the pertinent environmental attributes.
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For stability the studies must be conducted by qualified scientific and engineering personnel using approved means. The border includes the physiographic, hydrologic, ecologic, social, and political boundaries of the project areas. In general, the following types of file are required for characterization of the dredging and placement sites, the transport passageway, and the areas approximately these sites, which could be indirectly affected, to adequately address the scope of management options [5, 6]:
?Bathymetric and contiguous topographic data;?Habitat and species distribution;?Resources such as fish populations, shellfish beds,
cheap birkenstock, fuel and gas fields, total mining and spawning grounds;?Physical and chemical nature of sediments;?Water quality;?Hydrodynamic data;?Cultural resources, including archaeological and anthropological conditions;?Human demography and land use characteristics;?Users of the environmental resources, such as advertisement, recreational, and existence fisheries;?Navigation paths; and?Services in the project area, such as pipelines and cords.
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In appending, it is necessary to take into account any cumulative impacts. Certain ongoing activities, such as fisheries and navigation, could have impacts that in combination with the intended dredging result in more significant effects than would result from the project activities unattended. This information is generally included in the impact assessment.
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5.2 Between environmental risk assessment and environmental impact assessment
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In practice, another approach is used to reckon and "meter" the environmental impacts of a dredging project. ERA is defined as the checkup of risks resulting from the technology that threaten ecosystems, animals and people (EEA, 1998). There are three cardinal types of ERA: human health, ecological, and applied industrial risk assessment. The origin of ERA is the assessment of risks in the manufacture. Then, the same approach was applied in a broader scale for assessing the risks of the loosen of chemicals posed to people health. The more recently developed ecological risk assessment follows the same approach as human health ERA, but amplifying the assessed "end-points" to category other than human beings.
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A conventional approach of an environmental risk assessment begins with the problem formulation and the identification of the hazard (or hazards). Then, the possible ways of release of the hazard are estimated, and the exposure of those chosen target species is assessed. The final treads are the consequence assessment and the appraisal of the risk. Some of the steps require the use of models (e.g. the assessment of the release and the exposure), and the outcome is usually a quantitative assessment. It should be eminent that many choices must be done in the design of the risk assessment, and thus the definition and method used in each of them will be of importance to the final outcome [7].
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?The difference between ERA and EIA is that the later do not remedy risks as probabilities. Generally the potential impacts are prophesied, and assessed quantitatively or qualitatively. However, it also uses models requires for making many decisions in the design of the assessment, which could influence the ultimate result. Any evaluation of the impacts of a definite project has to face difficulties and uncertainties, in part due to the scientific uncertainties involved, but in part due to the decisions to be made for framing and defining the problem. The impact assessment will have to clarify the range of species to include and thus get embarrassed in nontrivial normative (ethical, ecological and economic) issues.
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5.3 Risk based design and precautionary principle
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n the context of dredging projects it can be stated that because of great natural variability there will often be a lack of full scientific certainty about the scales of potential impacts. In accordance with the Precautionary Principle decision to forego a project should be a last resort following exhaustive consideration of all reasonable RCO and reaching a conclusion that adequate environmental protection could not be fulfilled. Prohibiting dredging may ensure that no impacts occur, but may too generate high risk to human safety (e.g., lack of removal of shoals that pose navigation hazards) or result in lost trade and damage to the economic. The RCO should be selected such that clear, defined, and ideally quantitative thresholds of protection can be accomplished (e.g. to control measures of suspended sediment within a specified concentration / duration range). Work on environmental publish has always involved squabble because of impacts analysis.? Global climate Change might be regarded as a primary example where this lusty interlinkage between science and policy making is broadly recognized, Social science studies have shown how the production of scientific knowledge played a crucial part in the rise of climate change as a heading of international interest and to the political amphitheatre? while, on the other hand, knowledge and research on climate change issues is influenced by social factors
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In most countries, a cloud of dredged material is placed at sea. Land disposal options are normally much more expensive therefore, they are applied only when both transport costs to sea are inhibitory, or beneficial use is not an option, or the material is too contaminated (Burt et al., 1997a). In order to meet sustainability requirement the following describe 3 case studies where beneficial work in dredging are translated to cost [10,11].
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On environmental sustainability According to US green port project, 2001, case study on Boston port navigation correction project done in the US dredging and construction project use mitigation like? Surface sediments contaminated with metals, PAHs, PCB, and other organics, Channels were over-dredged by 20 ft. Contaminated material was placed on barge and deposited into over-dredged in-channel disposal cells and covered with 3 ft. wash material, All clean material deposited in Mass Bay Disposal Site.Another case done in port of los Angelis use copper treatment by developing? onsite system to treat copper contaminated marine sediments, Pilot study dredged, treated, and disposed of 100 tons of contaminated sediment, Full-scale project cleaned up 21,000 cubic yards of contaminated sediment, Saved $1.5 million in cleanup costs over alternative.Studies done in Europe also confirm use of processing factory for dredge material. Also regional sediment management program done by (USACE, 2003) compiled manifold methodologies to reduce shoaling.
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5.4 Reliability and determination aid framework
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??????????????? Various studies have been carried out to find the best hybrid afford for given areas. Results from specific studies cannot be lightly applied to other locations due to area-specific resources and energy-use profiles and environmental distinctions. Energy afford system, with a large percentage of renewable resources varies with the size and type of space, climate, place, typical demand outlines, and available renewable resource. A decision support structure is necessary in array to aid the design of future renewable stamina afford systems, mainly administer transitional periods, and encourages and advance state-of-the-art deployment as systems chance extra economically desirable. The DSS could comprise the technical feasibility of possible renewable energy supply systems, economic and political issues. ???
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??????????????? Reliability based DSS can assist possible supply scenarios to be immediately and easily tried, to see how well the demands for electricity, heat and transport for any given area can be matched with the outputs of a wide variety of possible generation methods. This includes the generation of electricity from intermittent hybrid sources. DSS framework provide the appropriate type and sizing of spinning reserve, fuel production and energy warehouse to be ascertained, and support the analysis of supplies and demands for an area of any type and geographical location, to allow potential renewable energy provision on the small to media scale to be analyzed. DSS can provide energy provision for port and help guide the transition towards higher percentage sustainable energy provision in larger areas. The hybrid configuration of how the total energy needs of an area may be met in a sustainable manner, the problems and benefits associated with these, and the ways in which they may be used together to form reliable and efficient energy supply systems. The applicability and relevance of the decision support framework are shown through the use of a can pretend case study of the complicated nature of sustainable energy supply system design.
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5.5 Regulatory requirement and assessment
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??????????????? The new valid requirements have been adult based on reactive approach which leads to system failure. Reactive approach is not suitable for presentation of fashionable technology of modern power generation systems. This cry for alternative philosophy to the assessment of new power generation technologies together with associated equipment and systems from safety and reliability considerations, such system required analysis of system capability and regulatory capability. System based approaches for regulatory assessment is detailed under goal based design as shown in figure.
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??????????????? IMO has embraced the use of goal based standards for ship construction and this process can be equally well applied to machinery power plants.
Legal framework for dredging
The most important international agreements regarding dredging are the London Convention 10, issued in 1972 and reviewed in the 1996 Protocol 11; and the OSPAR Convention 12 from 1992. IMO also unveil Formal safety assessment for marine system. These international concerts establish frameworks within which the contracting countries are obliged to manipulate with adore to their handling of materials preordained for placement in the sea. However, these Conventions do not include regulations of the dredging operations per se, which are mainly established at the national level, neither for the conditions of disposal of in land. Convention for the prevention of marine pollution by dumping of wastes and other material (www.londonconvention.org).
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A review of the Convention began in 1993 and was completed in 1996 with the approval of The 1996 Protocol to the London Convention. The 1996 Protocol has at present come into coerce as it has not yet been ratified by a ample digit of countries (19 out of 26). Conventions for the Protection of the Marine Environment of the North-East Atlantic (www.ospar.org).On the other hand, dredging activities are subject to national regulations, which can alter very much among the countries. In some cases there is a specific directive regarding dredging in Malaysia the imperial Malaysia marine regulate the dredging. Thus the are other agencies merely there is not integration for effectiveness of the system.(private communication .
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5.2?? Quantitative and prim system engineering based risk analysis
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"Risk" is generally understood as an expression of the quantified correlate among an environmental risk or "stressor" and the potential negative consequences it may have on targets or "receptors". When discussing risk the types of stressors as well as the targets of amuse must be specified. Thus project risk can be distinguished from engineering risk, and environmental risk. But, in practice it may be quite difficult to establish a quantifiable relationship between risk and target feedback because of the many uncertainties in the cause-effect fetter and the dynamic nature of aquatic ecosystems. Risk thinking provides a means to adjust these uncertainties. Formal risk appraisal programs have not been adopted along many regulatory agencies or they have been applied primarily to dredging of contaminated sediments. Typically risk assessment takes the manner of "vocational judgment" based on the experience and expertise of parties busy in project co-ordination [12].
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Risk analysis provides an opportunity to focus on the real concerns of a project, instead of depending on fixed and inflexible standards such as threshold levels for contaminants or fixed percentages of lawful flood of a dredger. For the purpose of this report, risk assessment is mainly arrested in the EIA, though risk management takes the form of best management practice determination. Risk evaluation is the way from the scientific system based quantitative risk analysis is the internationally recognized best practice and meek conception of risk analysis. Table shows components of risk analysis.
???????????????? The design concept needs to address the marine environment in terms of those imposed on the power plant and those that are internally controlled. It is also necessary to address the effects of launch, flooding, equipment failure and the capability of personnel required to operate the system. In carrying out a hazard assessment it is vital that there are apparently defined objectives in terms of what is to be demonstrated. The assessment should address the consequence of a hazard and possible effect on the system, its subsystems, personnel and the environment. An assessment for reliability and availability of a hybrid power generation system and its installation in a ship could use a FMEA tool. An effective FMEA needs a structured approach with clearly defined objectives
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??????????????? The assessment analysis processes for safety and reliability need to identify defined objectives under system functionality and capacity matching. These two issues are cared with system performance rather than compliance with a prescriptive prerequisite in a standard. The magnitude of performance and integration of systems that are related to safety and reliability is now acknowledged and the assessment tools immediately available offer such means. Formal Safety Assessment (FSA) is recognized by the IMO as being an important portion of a process for formative requirements for marine regulations. IMO has accepted Guidelines for Formal Safety Assessment (FSA) for use in the IMO rule-making process (MSC/Circ.1023/MEPC/ Circ.392). Further reliability and optimization can be done by using stochastic and simulation tools [8, 13].
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5.4 Uncertainties and risk in dredging projects
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The physical and biological specifics of aquatic environments vary both spatially and temporally. Therefore characterizing these environments and assessing impacts and risk will forever involve some uncertainty. This requires the need for elementary comprehending of how seaman and the ecosystems feature and how natural events and anthropogenic activities influence these functions. In the ideal situation, all environmental risks associated with a dredging project would be quantifiable, production the need for specific management practices clear. In reality, dredging can potentially affect unlike assemblages of creatures or their habitats on both spatial and temporal scales. Because the scales of the interactions between organisms and the dredging process are difficult to determine, often the consequences of a project are largely speculative. Some degree of uncertainty will therefore always be present indecisions regarding the need for special management practices to defend the environment.
?5.4.1 Potential Physical Changes and Environmental Impacts from Dredging and Disposal of Dredged Material
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Below water, the sound from the dredge vessel could have environmental effects such as interfering with fish behavior, maybe leading to afflicted migratory routes, though fish might easily shirk temporarily disturbed areas without consequence. Other potential environmental effects not directly relative to dredging but associated with the presence of the dredger include spills of oil and oil, exhaust emissions, and the possible introduction of invasive species via the release of ballast water.One of the fewer understood areas of concern is the impact of sediment released into the aquatic environment that may occur at any of the stages from excavation to placement. A high concentration of sand in suspension will have very low turbidity while a relatively low concentration of fine silt or clay in suspension will have a high turbidity.? ALlso sediment effect on the flora and fauna, concentration, the turbidity, the total amount of wastage of sediments or the spatial distribution of a sediment plume are other impacts.
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5.4.2 Spatial and Temporal Scales of Effects: The environmental effects vary spatially and temporally from project to project. When the effects are considered to have a significant detrimental impact it is necessary to investigate means to reduce or mitigate them. The significance of the environmental effects depends on site-specific factors that govern the vulnerability and sensitivity of environmental resources in the project area. When the sediment being moved is chemically contaminated, the need for environmental protection is generally recognized by all stakeholders.
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Complexity with respect to uncertainty has made essential for several exertions to find tools for the assessment and management of different types of uncertainty. As said before, the word uncertainty is used in many different situations for expressing a lack of certain, clear knowledge for taking a decision. Uncertainty is any departure from the unachievable ideal of complete determinism. In the case presented here, uncertainty signifies that is not possible to provide a unique, undisputable, objective assessment of a certain action (case in point an environmental risk assessment of the dredging). However, depending on the player (e.g. the modeller, the policy-maker, or stakeholders), the prescience of the nature, variety, object and signification of uncertainty can be very different. This will be clear when presenting the prescience of uncertainty of the stakeholders involved in the case. Nevertheless, the simple definition presented above gets more intricate when attempting to describe the sources, or the sorts or dimensions of uncertainty.
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Typology approaches adopted for characterization and assessment of uncertainty by this group focus on uncertainties encountered from the point of view of the modeler that assesses policy-makers (which they call model based decision support). Therefore, their proposition aims to be useful for expressing the uncertainty involved in the use of models, maybe rather than expressing uncertainty from the point of view of the policy-makers or stakeholders. The typology is based in the distinction of three dimensions of uncertainty:
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i the location of uncertainty (where within the model);
ii the level of uncertainty (from deterministic knowledge to total ignorance); and,
iii the nature of uncertainty (whether the uncertainty is due to the imperfection of our knowledge or is due to the inherent variability of the phenomena being narrated).
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5.5 Risk communication and management
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Parties involved in a dredging project outlook the process differently depending on their individual perceptions of these risks and rewards, as well as their individual tolerance of the perceived risk. In this sense there may be several types of risk in a project. For the proponent the consequences of failure of the whole project may be very caustic and will usually be measured in frugal terms. For an environmentalist the potential effects on the environment may be recognized as the maximum prerogative risk. Communication is an essential component of sharing concerns and identifying means to alleviate them to the fullest amplitude reasonably possible. During the risk analysis, it is important to balance the identified environmental effects and risks against the economic and social consequences of the project. Complete and transparent communications are therefore essential throughout the process from starting to end. This refers to all parties involved. Communication should address uncertainties and natural variability in the environment. Seldom does an actual project present a clear choice between unbiased, independent, and generally accepted options. Rather, the alternative among options is frequently pedaled by values and perceptions. This traction can best be reduced through open lines of communication that include:
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?A transparent process;?Outreach that begins during the premier possible stage of the project and continues throughout always phases;?An open and aboveboard process; and?Proactive vow of regional and/or regional medium, because their inspire aboard public opinion can be large.
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5.6 Selecting evaluation and risk control option for dredging project
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Action might be taken to adjust the monitoring program itself or as a straight response to the monitoring results. Based on the monitoring data, adjustments to the monitoring program could include:Reducing the level of monitoring because no effect was observed;Continuing with the existing monitoring program to acquisition further clarification of the response; orExpanding the monitoring program to include annexed parameters or sites.So that reacting can be quick and effective, it is necessary to establish hierarchy of options to adverse monitoring results. The level of response can be targeted to the receptor and its sensitivity. Options could include:Continuing with dredging under the existing regime;Modifying the dredging regime to reduce the actual effect on a sensitive parameter;Ceasing dredging within an area until further information is gathered;Ceasing dredging within an area altogether; orCeasing dredging and implementing recovery measures.
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For a monitoring program to be entirely efficacious,
tiger onitsuka, it must include a timely communication of results and related actions. Stakeholders should be involved to help establish overall program credibility.
Risk control options are averaged to improve the environmental performance of a dredging project. Some form of environmental evaluation or Environmental Impact Assessment (EIA) is usually required by worldwide conventions. One example is the London Convention, which establishes a framework for the evaluation of placement of dredged material at sea. The "Specific Guidelines for Assessment of Dredged Material" (International Maritime Organization, 2000) comprises the following steps:
Dredged material characterization;Waste obstruction audit and evaluation of disposal options;Is the material acceptable for marine placement?;Identify and represent the placement site;Determine potential impacts and prepare impact hypothesis(ies);Issue allow;Implement project and monitor compliance; andField monitoring and assessment.Within the LC-DMAF guidance it is stated that
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All dredging and placement projects will reason some changes to the environment. It is therefore needful to determine whether these can be considered serious and or irreversible. Because ample information is rarely available to question these questions with perfect certainty, an appraisal of the relative risk of lasting loss to the environment is required. Many factors affect this assessment of the general environmental risk including the scale of the project, the natural variability of all of the elements of the system likely to be affected, possible contamination levels, and the timing of the project. Preparation of an EIA involves collaboration among environmental scientists and engineers in consultation with wharf authorities, dredging companies, and often a diverse assemblage of stakeholders. The quantity of technical information available will be important, but should be used in tandem with the perceptions and knowledge held by the engaged stakeholders. Risk appraisal is a value judgment reached by consideration of the total body of testify offered by all interested parties.
These constrains are very important to bear in idea while we consider of environmental management by the local or regional level with projects with are used limited time and allowance of money. Therefore the lack of knowledge that can be experienced by both managers and inhabitants in assessing a concrete project may have more to do with limited resources than general scientific ignorance. Benefit-Cost Analysis (BCA) is a tool for organizing information on the relating value of option public investments like environmental restoration projects. When the value of all meaningful benefits and costs can be expressed in financial terms, the web value (benefits minus costs) of the alternatives beneath attention can be calculated and used to identify the option that yields the greatest mushroom in public welfare. However, since environmental merchandise and services are not commonly bought just aboutld in the marketplace, it can be difficult to express the outputs of an environmental restoration project in monetary terms.
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Risk monitoring
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It is acknowledged that monitoring can take many forms and fulfill various objectives ahead, during, and after any dredging and placement project. This document does not provide an exhaustive description of monitoring technology but rather focuses on the character of monitoring as a necessary element in the context of BMP application. In particular, monitoring can be proposed as a management practice in itself or used to assess the effect of other management practices. Monitoring is the premier step-in determining whether disciplinary actions will be necessary to ensure the required outcomes [13,14].
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One of the key issues related to any environmental monitoring program is the scope for combining roomy monitoring objectives for divide parameters into a single survey. Monitoring programmes can be categorized into three types:
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Surveillance monitoringFeedback monitoringCompliance monitoring
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Formulating a appropriate monitoring strategy requires the retinue elements:
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Targeted objectiveBeeline conditionMonitoring criteriaMethodology for measuring changeThreshold valuesTimely review procedure
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Requirements for monitoring are site-specific and based on the discoveries of the baseline surveys. For example, surveys could be necessary to record:
The abundance and distribution of species, which is needed to determinethe rate of species and community recovery within the study area;?The effect of dredging on seabed morphology;?The effect of dredging on the concentration of suspended sediments in the water column;?The type of substrate remaining following dredging;?Use of the area by fish; and?Actual effects on any acute species or communities within the study area.
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Sometimes, model studies can be used to make sure the appropriate locations for monitoring. Monitoring involves many uncertainties and difficulties that need to be considered. Models are generally not well verified or calibrated and so it is not effortless to quantify the results with assurance although they are continually improving. After the monitoring criteria have been selected, the methodology for measuring change against those criteria needs to be determined.
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The monitoring could be in the water col, on the seabed, on land or in the climate. It could be physical, chemical, or biological or a composition. Key considerations in establishing the monitoring methodology are briefed below:
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The methodology used to monitor environmental effects should be the same as that used to determine the characteristics of the relevant parameter during the baseline examine, to ensure comparability.The sampling stations should be the same, although there are likely to be fewer stations (e.g., the feature of interest may require a more targeted approach than was adopted for the baseline survey).For parameters where timing is fussy (e.g., benthic and fish sampling), repeat surveys should be undertaken in the meantime of year as the baseline survey to ensure that seasonal changes in abundance and distribution do not affect the results.The frequency of sampling is determined based on the monitoring objectives and criteria. The anticipated impact is also a factor to consider when determining frequency of sampling. Fhardly everme parameters (e.g., impacts on geology), changes occur over a long time scale and therefore require less prevalent monitoring, possibly post project.
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It is major to identify a level above or below which one achieve is thought unacceptable, referred to as an environmental threshold. If the monitoring shows that the threshold level is close to being approached then remedial movement is required to decrease the level of achieve. In the deficiency of a threshold merit, monitoring of many parameters is justified to improve the wisdom bottom of the particular effect. Timely review of monitoring results is necessity to ensure the success of the procedure. It is recommended that the results of monitoring should be reviewed at times that will permit for significant adjustments to the dredging and nestle activities.
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Conclusions
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??????????????? Dredging provides economic and social benefits for the whole community. However dredging can and often will have an impact on the environment appearance of the desired change, of say deepening a channel. To assess the significance of these effects an environmental impact study often needs to be undertaken. During such a study, cumulative and in-combination effects should be considered as it is important to area the dredging activity into context with other activities, e.g., fisheries, navigation, etc. Previous regulatory work for system design has been prescriptive by nature. Performance based standards that make use of alternative methods of assessment for safety and reliability of component design,
hogan home, manufacture and testing is recommended for hybrid alternative energy system installation.
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System failure and carefree of environment in quondam project poised all field of human endeavor to adopt precautionary conviction by providing tools to conduct dredging projects in an environmentally sound means and design based on comprehensive system based scientific method discussed in this paper. Properly applied the precautionary principle provides stimuli to develop better solutions. The paper present structured approach and strives for an objective means of selecting the most appropriate Risk control option for that lead to the best protection of the environment and encounter sustainable evolution requirement. Absolute Reliability of the dredge work can be achieve by using predictive statistical tools and the data collected.
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Reference
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[1] Erftemeijer PLA and Lewis III RRL (2006): Environmental impacts of dredging on seagrasses: A review. Marine Pollution Bulletin 52, pp. 1553-1512
[2] Herbich JB (2000): Handbook of Dredging Engineering, 2nd Edition. McGraw-Hill Professional, 992 pages
[3] International Maritime Organization (IMO) 2000): Specific guidelines for assessment of dredged material
[4] John SA, Challinor SL, Simpson M, BurtTN and Spearman J (2000). Scoping the assessment of sediment plumes from dredging. CIRIA Report C547, London,190 pages
[5] Keevin TM, (1998): A review of Natural Resource Agency Recommendations for Mitigating the Impacts of Underwater Blasting. Reviews in Fishery Science, pp. 281-313
[6] New Delta Project (2007): Final report of Theme 6 ��Sustainable Dredging Strategies'. Framework for a sustainable dredging strategy. 2007, 48 pages www.newDelta.org
[7] OSPAR (2007): Draft literature review on the impacts of dredged sediment disposal at sea. Document Nr. EIHA 07/2/2-E
[8] International Maritime Organization (IMO). Amendments to the Guidelines for Formal Safety Assessment (FSA) for Use in the IMO Rule Making Process. MSC �C MEPC.2/Circ 5 (MSC/Circ.1023 �C MEPC/Cir. 2006 [9] PIANC (2006): Working Group Envicom 10: Environmental risk assessment of dredging and disposal operations.
10] PIANC (2008): Working Group Envicom14: Dredged material as a resource options and constraints
?[11] PIANC Working Group Envicom 16:Dredging and port construction around Coral Reefs t.b.p.
12] Rees HL, Murray LA, Waldock R, BolamSG, Limpenny DS and Mason CE (2002): Dredged material from port developments: A case study of options for effective environmental management.
[13] EPA (2001): Guidelines for dredging. Best practice environmental management. Environment Protection Authority, Victoria, Australia. Publication 691. 116pages.
[14] PIANC (1998) Working Group PTC I-17: Handling and management of contaminated dredged material from ports and inland waterways "CDM"
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enter the market during this period, many global companie enter the field for manufacturing
share. The American population fell in love with the Nike Dunks SB. Many competing products
over the years. In the 20th century, early 80s, most of the basketball fans captured the market
Environmental Reliability for Sustainable Dredging
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