Chapter 6 GARDGuide.The most recent and widely accepted methods for the prevention and mitigation of ARD see Chapter 1 for definition are presented in this Chapter.Discussions include the principles and objectives for prevention and mitigation and definitions and terms, suitability and applications, expectations and limitations, and primary references.While this chapter focuses on environmental technologies, regulatory, social, economic, and sustainability issues must always be managed within the applications of all prevention and mitigation techniques.As discussed in Chapter 2, sulphide mineral oxidation occurs naturally as part of the sulphur cycle.In the context of ARD management during mining, the goal of mitigation measures is often to maintain or control the rate of sulphide mineral oxidation so that ARD formation is prevented or reduced to minimal or acceptable levels.Absolute prevention of ARD may require that all reactive sulphide bearing minerals remain virtually isolated from atmospheric oxygen.However, absolute prevention of ARD may not always be required for protection of environmental quality.The basic approaches to prevent ARD are similar at coal mines and hard rock mines reducing oxygen ingress and reducing the flow of water that can act as a transport medium for oxidation products.Coal mines may make use of low permeability covers, or selectively place pyritic material high in the backfill so that it will not be exposed to ground water.Pyritic material can also be mixed with alkaline strata or some added alkaline material or by product e.H gets low enough to permit iron oxidizing bacteria and ferric oxidation of pyrite to become significant Brady et al., 1.Perry and Brady, 1.Rich and Hutchison, 1.Rose et al., 1. 99.Skousen and Larew, 1.Smith and Brady 1.Wiram and Naumann, 1.These latter techniques have also been applied with some modifications at hard rock mines, as will be discussed later in this chapter.Lucy%E2%80%99s+Rib+Cage+Brad+Harrub+%28Ph.D.+Anatomy+and+Neurobiology%29+and+Bert+Thompson+%28Ph.D.+Microbiology%29%2C+The+Truth+About+Human+Origins%2C+2003%2C+p.+47..jpg' alt='Design Of Small Dams Fourth Edition Microbiology With Diseases' title='Design Of Small Dams Fourth Edition Microbiology With Diseases' />6.Prevention And Mitigation.Introduction 6. 2 Goals and Objectives of Prevention and Mitigation 6.Approach to Acid Rock Drainage Prevention and Mitigation.International Journal of Engineering Research and Applications IJERA is an open access online peer reviewed international journal that publishes research.The implementation of methods for prevention and mitigation depends on the mine development stage, deposit type, geochemistry, climatic regime, terrain or topography, surface water, geology, groundwater, and aquatic and terrestrial ecosystems.Material availability, land management and land use requirements, receptors, risk, cost, maintenance, sustainability and regulatory requirements will also influence the approach selected.It is important to recognize that the science and engineering of ARD management, especially related to prevention and mitigation, are evolving.There are no off the shelf solutions that can be applied at all sites that will guarantee acceptable water quality through prevention of ARD or leaching of soluble constituents from mine rock, tailings or other mine materials.Therefore, the planning for and management of mine material handling and storage should be considered in a risk based framework.While a risk based approach should apply to other aspects of ARD such as prediction, as discussed in Chapter 5 of this Guide, it is especially relevant to the planning and implementation of prevention and mitigation methods that will inevitably have unique features and issues that are associated with site specific and mine specific conditions.Prevention and mitigation of ARD is an exercise in water quality management.One important feature of managing water quality associated with mine materials is delay times between implementation of remedial activities and observed or measured water quality from a facility such as a mine rock stockpile or a tailings impoundment.Delay times between implementation and monitoring or measurement of effects often result in the need for long periods of monitoring or testing to determine the outcomes of implemented methods.There is a growing foundation of long term studies and case histories for prevention and mitigation strategies in the literature and in practice at many operations.With the exception of water covers that are relatively well understood, the scientific and engineering community are on an ongoing learning curve for many of the other ARD management approaches.Therefore, prevention and mitigation planning should be undertaken with due consideration of key uncertainties and appropriate management of risks to achieve the desired outcomes. Microsoft Office Enterprise 2010 Corporate Final Activated Charcoal Teeth . While it is not practical to wait years or decades to confirm successful performance of proposed waste management methods, adaptive management techniques are needed and appropriate to respond to unexpected responses while maintaining environmental protection and cost control.An understanding of delayed responses to test conditions or mitigation activities is important to anticipate potential outcomes and to correctly interpret data collected from tests or full scale facilities.In some cases, delays can result from chemical behavior.The time to deplete neutralization potential NP and to the onset of low p.H conditions is an obvious example of such delays.In this case, we understand the process of NP depletion and with the appropriate data, the depletion times can be estimated even if test results did not exhibit depletion.There are other, more subtle, changes that can also occur over time that can represent delays as well.For example, Rinker et al.L. In that case, the elevated nickel values were triggered by a p.H shift from 8 to 7.Design Of Small Dams Fourth Edition Microbiology' title='Design Of Small Dams Fourth Edition Microbiology' />After recognizing the mechanism that was responsible for the increased nickel, the process and the outcome can be accounted for and therefore managed as required.Similar delays in metal release were observed in field scale mine rock pile tests at a copper zinc mine in South America.The test piles had been operating for four years with relatively low metal concentrations in the drainage.A shift in p. H from 7.L range in the drainage samples.Although delays from chemical processes like those described in the previous paragraph can occur, the more common causes of delays are generally related to the hydraulics of rock piles and tailings facilities, or a combination of hydraulics and chemical reactions.The hydraulics or hydrology of mine rock piles and tailings deposits are relatively well understood and can be evaluated with proven science and engineering principles.Combining the hydraulic and chemical behavior is somewhat more complex, but conceptual models can be developed and translated to quantitative models or calculations as discussed in Section 5.Nonetheless, the monitoring of such facilities to assess performance of mitigation measures is not always straight forward.For example, it is not easy to measure leaching or water quality effects in a field scale rock pile.Therefore, it is often necessary to collect and monitor drainage at the base of the pile.Depending on the size of the pile, this could represent years of delay between the changes that may occur in the pile and those observed in the drainage.The processes would therefore normally be modeled to better understand the expected water quality and timeframe for anticipated changes, and the modeling results would guide the monitoring program.This chapter emphasizes examples and case histories in an attempt to assist the reader in understanding approaches to prevention and mitigation strategies that have been applied and for which performance data are available.Prevention is a proactive strategy that obviates the need for the reactive approach to mitigation.Mitigation will be the usual initial course of action for an existing case of mine drainage that is adversely impacting the environment.Despite this initial action, subsequent preventative measures may also need to be considered in the context of reducing future contaminant load, and thus reducing the ongoing need for mitigation controls.For example, the amount of seepage requiring treatment may be reduced if the current source strength is reduced.Latest environmental news, features and updates.Pictures, video and more.For both prevention and mitigation, the strategic objectives must be identified because, to a large extent, these strategic objectives will define the control methods that need to be used.The process of identifying the strategic objectives should consider the following.ARDML prevention is the key to avoid costly mitigation.ARD, NMD, and SD are all the result of natural weathering processes that occur under atmospheric conditions.An error occurred while setting your user cookie.Please set your. browser to accept cookies to continue.NEJM. org uses cookies to improve performance by remembering your.ID when you navigate from page to page.This cookie stores just a.ID no other information is captured.Accepting the NEJM cookie is.
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