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Alex S. Mayer - One of the best experts on this subject based on the ideXlab platform.
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Optimal design of Pump-and-Treat systems under uncertain hydraulic conductivity and plume distribution
Journal of Contaminant Hydrology, 2008Co-Authors: Domenico Baù, Alex S. MayerAbstract:In this work, we present a stochastic optimal control framework for assisting the management of the cleanup by Pump-and-Treat of polluted shallow aquifers. In the problem being investigated, hydraulic conductivity distribution and dissolved contaminant plume location are considered as the uncertain variables. The framework considers the subdivision of the cleanup horizon in a number of stress periods over which the Pumping policy implemented until that stage is dynamically adjusted based upon new information that has become available in the previous stages. In particular, by following a geostatistical approach, we study the idea of monitoring the cumulative contaminant mass extracted from the installed recovery wells, and using these measurements to generate conditional realizations of the hydraulic conductivity field. These realizations are thus used to obtain a more accurate evaluation of the initial plume distribution, and modify accordingly the design of the Pump-and-Treat system for the remainder of the remedial process. The study indicates that measurements of contaminant mass extracted from Pumping wells retain valuable information about the plume location and the spatial heterogeneity characterizing the hydraulic conductivity field. However, such an information may prove quite soft, particularly in the instances where recovery wells are installed in regions where contaminant concentration is low or zero. On the other hand, integrated solute mass measurements may effectively allow for reducing parameter uncertainty and identifying the plume distribution if more recovery wells are available, in particular in the early stages of the cleanup process.
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Equilibrium versus Nonequilibrium Treatment Modeling in the Optimal Design of Pump-and-Treat Groundwater Remediation Systems
Journal of Environmental Engineering, 2007Co-Authors: Karen L. Endres, Alex S. Mayer, David W. HandAbstract:The present work proposes that the incorporation of granular activated carbon (GAC) Treatment model that accounts for nonequilibrium adsorption into the optimal design of Pump-and-Treat systems will result in more realistic costs and better-engineered remediation systems. It was found that, when nonequilibrium GAC adsorption effects are considered, the predicted cost of optimal remediation strategies increases consistently when compared to costs obtained assuming equilibrium GAC adsorption, for a wide range of cleanup goals. This finding implies that when simpler equilibrium models are used for GAC adsorption, cleanup costs will be underestimated. GAC Treatment costs are shown to be particularly sensitive to the degree of mass transfer limitations in the aquifer–contaminant system, especially when nonequilibrium GAC adsorption is accounted for. Time-varying Pumping rates are shown to produce more efficient remediation solutions; the increase in efficiency is even more pronounced when nonequilibrium GAC ad...
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Stochastic management of Pump-and-Treat strategies using surrogate functions
Advances in Water Resources, 2006Co-Authors: Domenico Baù, Alex S. MayerAbstract:Typical Pump-and-Treat (PAT) optimization problems involve design of Pumping schemes, while minimizing cost and meeting a set of constraints. Due to scarcity of information about the hydrogeological system, stochastic modeling approaches can be used to assess tradeoffs between optimality and reliability. Using a stochastic approach, the constrained, single-objective problem may be turned into a multiobjective problem by substituting constraint inequalities with an additional objective function (OF) that accounts for the reliability of the PAT process. In this work, two approaches are analyzed: in one case, the additional OF consists of the probability of failure of a given remediation policy; in another, the OF additional is represented by the recourse, namely the penalty cost induced by the violation of constraints. In order to overcome the overwhelming computational cost required by stochastic simulation, surrogate forms of the OFs are introduced. In the test case under investigation, such functions are estimated by a kriging interpolation of the OF over a series of data points obtained from stochastic simulations of flow and transport, and calibrated against stochastic optimization solutions. The analysis of the two approaches for addressing the tradeoff of cost vs. reliability indicates that recourse accounts not only for the frequency of constraint violations, as the probability of failure does, but also for the intensity with which these occur. Ultimately, the recourse method allows considering less restrictive policies, although these may be highly sensitive to the choice of penalty functions.
Georg Teutsch - One of the best experts on this subject based on the ideXlab platform.
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Cost‐optimal contaminant plume management with a combination of Pump‐and‐Treat and physical barrier systems
Groundwater Monitoring & Remediation, 2005Co-Authors: Peter Bayer, Michael Finkel, Georg TeutschAbstract:The economic potential of combining hydraulic barriers and Pump-and-Treat systems to manage contaminant plumes is investigated by means of a comparative cost analysis. The analysis is based on a preceding study on the hydraulic performance of barrier-supported and conventional Pump-and-Treat systems, which revealed the efficiency of accurately positioned barriers in reducing Pumping rates for contaminant plume capture. In the present paper, we examine whether the application of physical barriers like slurry walls or sheet piles also leads to economic benefits, i.e., whether the reduction of the operational costs outweighs the capital costs associated with the construction of the barriers. An economic model is presented that quantifies remediation costs by the use of cost functions relating costs to site-specific and system-specific parameters. The model is applied to a hypothetical remediation scenario. The results clearly demonstrate that physical barriers may yield significant savings in the total costs, particularly if unit costs for on-site Treatment are high. Furthermore, as barriers tend to reduce the uncertainty about the Pumping rate required to capture a plume, they smooth the trade-off curves between total remediation costs and system reliability.
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cost optimal contaminant plume management with a combination of Pump and Treat and physical barrier systems
Ground Water Monitoring and Remediation, 2005Co-Authors: Peter Bayer, Michael Finkel, Georg TeutschAbstract:The economic potential of combining hydraulic barriers and Pump-and-Treat systems to manage contaminant plumes is investigated by means of a comparative cost analysis. The analysis is based on a preceding study on the hydraulic performance of barrier-supported and conventional Pump-and-Treat systems, which revealed the efficiency of accurately positioned barriers in reducing Pumping rates for contaminant plume capture. In the present paper, we examine whether the application of physical barriers like slurry walls or sheet piles also leads to economic benefits, i.e., whether the reduction of the operational costs outweighs the capital costs associated with the construction of the barriers. An economic model is presented that quantifies remediation costs by the use of cost functions relating costs to site-specific and system-specific parameters. The model is applied to a hypothetical remediation scenario. The results clearly demonstrate that physical barriers may yield significant savings in the total costs, particularly if unit costs for on-site Treatment are high. Furthermore, as barriers tend to reduce the uncertainty about the Pumping rate required to capture a plume, they smooth the trade-off curves between total remediation costs and system reliability.
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kombinierte Pump and Treat barrieren systeme teil i minimierung der grundwasserentnahmerate durch hydraulische zusatzmasnahmen
Grundwasser, 2004Co-Authors: Peter Bayer, Michael Finkel, Georg TeutschAbstract:Das „Pump-and-Treat“-Verfahren ist trotz seiner durch Schadstofffreisetzungsraten und -ruckhalt bekanntermasen limitierten Sanierungsleistung aufgrund seiner Einfachheit und Flexibilitat ein nach wie vor haufig in der Sanierungspraxis angewendetes Verfahren. Als Konsequenz aus den Erfahrungen der Vergangenheit ist diese Technologie jedoch von vornherein auf sehr lange Betriebszeiten (> 30 Jahre) auszulegen. Damit werden die Betriebskosten zum entscheidenden okonomischen Faktor. In dieser Arbeit werden verschiedene kombinierte „Pump-and-Treat“-Barrieren-Systeme ( PT +) vorgestellt, bei denen mittels hydraulischer Zusatzmasnahmen eine Reduzierung der zur Sicherung eines Schadensherdes bzw. einer Verdachtsflache erforderlichen Grundwasserentnahmerate erreicht wird. Hierbei wird auf eine Minimierung der mit Grundwasserforderung und -aufbereitung verbundenen Betriebskosten abgezielt. In einer systematischen Szenarienanalyse werden zahlreiche Konfigurationen hydraulischer Barrieren und/oder Abwehrbrunnen untersucht und optimale Anordnungen bestimmt. Die Ergebnisse zeigen, dass die Grundwasserentnahmerate mit PT+ um bis zu 90 % des ursprunglichen Grundwasservolumenstroms durch den Schadensherd (der Verdachtsflache) reduziert werden kann. Die vorliegende Arbeit liefert die Grundlage fur eine vergleichende Kostenanalyse von PT+ und konventionellen „Pump-and-Treat“-Sanierungskonzepten ( BAYER et al. 2004).
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Kombinierte ?Pump-and-Treat?-Barrieren-Systeme, Teil I: Minimierung der Grundwasserentnahmerate durch hydraulische Zusatzmanahmen@@@Pump-and-Treat-Systems in Combination With Hydraulic Barriers?Part I: Minimising the Pumping Rate by Auxiliary Hydraul
Grundwasser, 2004Co-Authors: Peter Bayer, Michael Finkel, Georg TeutschAbstract:Das „Pump-and-Treat“-Verfahren ist trotz seiner durch Schadstofffreisetzungsraten und -ruckhalt bekanntermasen limitierten Sanierungsleistung aufgrund seiner Einfachheit und Flexibilitat ein nach wie vor haufig in der Sanierungspraxis angewendetes Verfahren. Als Konsequenz aus den Erfahrungen der Vergangenheit ist diese Technologie jedoch von vornherein auf sehr lange Betriebszeiten (> 30 Jahre) auszulegen. Damit werden die Betriebskosten zum entscheidenden okonomischen Faktor. In dieser Arbeit werden verschiedene kombinierte „Pump-and-Treat“-Barrieren-Systeme ( PT +) vorgestellt, bei denen mittels hydraulischer Zusatzmasnahmen eine Reduzierung der zur Sicherung eines Schadensherdes bzw. einer Verdachtsflache erforderlichen Grundwasserentnahmerate erreicht wird. Hierbei wird auf eine Minimierung der mit Grundwasserforderung und -aufbereitung verbundenen Betriebskosten abgezielt. In einer systematischen Szenarienanalyse werden zahlreiche Konfigurationen hydraulischer Barrieren und/oder Abwehrbrunnen untersucht und optimale Anordnungen bestimmt. Die Ergebnisse zeigen, dass die Grundwasserentnahmerate mit PT+ um bis zu 90 % des ursprunglichen Grundwasservolumenstroms durch den Schadensherd (der Verdachtsflache) reduziert werden kann. Die vorliegende Arbeit liefert die Grundlage fur eine vergleichende Kostenanalyse von PT+ und konventionellen „Pump-and-Treat“-Sanierungskonzepten ( BAYER et al. 2004).
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Combining Pump-and-Treat and physical barriers for contaminant plume control.
Ground Water, 2004Co-Authors: Peter Bayer, Michael Finkel, Georg TeutschAbstract:A detailed analysis is presented of the hydraulic efficiency of plume management alternatives that combine a conventional Pump-and-Treat system with vertical, physical hydraulic barriers such as slurry walls or sheet piles. Various design settings are examined for their potential to reduce the Pumping rate needed to obtain a complete capture of a given contaminated area. Using established modeling techniques for flow and transport, those barrier configurations (specified by location, shape, and length) that yield a maximum reduction of the Pumping rate are identified assuming homogeneous aquifer conditions. Selected configurations are further analyzed concerning their hydraulic performance under heterogeneous aquifer conditions by means of a stochastic approach (Monte Carlo simulations) with aquifer transmissivity as a random space function. The results show that physical barriers are an appropriate means to decrease expected (mean) Pumping rates, as well as the variance of the corresponding Pumping rate distribution at any given degree of heterogeneity. The methodology presented can be transferred easily to other aquifer scenarios, provided some basic premises are fulfilled, and may serve as a basis for reducing the Pumping rate in existing Pump-and-Treat systems.
Kang-kun Lee - One of the best experts on this subject based on the ideXlab platform.
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a study on Pump and Treat design through evaluation of radius of influence
Journal of Soil and Groundwater Environment, 2014Co-Authors: Jeong-woo Kim, Kang-kun LeeAbstract:It is necessary to decide the Pumping rate and Pumping well location together with the capture zone in order to determine an appropriate groundwater remediation strategy to manage the contaminated groundwater. The relationship between the capture zone and the drawdown radius of influence (ROIs) was considered. ROIcs is defined as the distance where the criteria of drawdown is cs meter from Pumping well in this paper. A method to decide the required Pumping rate for the remediation of contaminated groundwater in order to create appropriate ROIcs is suggested by using the Theis equation (1935) and Cooper-Jacob equation (1946). It was shown in this study that ROIcs is in proportion to the Pumping rate and the criteria of drawdown, which decides ROIcs, is inversely proportional to Ti value (transmissivity × hydraulic gradient). The Pumping rate which creates the required ROIcs could be planned through the relationship between the ROIcs and Pumping rates (ROIcs-Q curve) of the field sites 1, 2 and 3. If the drawdown is investigated along with Ti value and Pumping rate at a specific site where Pump and Treat remediation is planned, it is expected that the required criteria of drawdown can be evaluated by using the relationship between the cs and Ti (cs-Ti curve).
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Information effect on remediation design of contaminated aquifers using the Pump and Treat method
Stochastic Environmental Research and Risk Assessment, 2009Co-Authors: Kang-kun LeeAbstract:We examine the effect of uncertainty due to limited information on the remediation design of a contaminated aquifer using the Pump and Treat method. The hydraulic conductivity and contaminant concentration distributions for a fictitious contaminated aquifer are generated assuming a limited number of sampling locations. Stochastic optimization with multiple realizations is used to account for aquifer uncertainty. The optimization process involves a genetic algorithm (GA). As the number of realizations increases, a greater extraction rate and more wells are needed. There was a total cost increase, but the optimal remediation designs became more reliable. Stochastic optimization analysis also determines the locations for extraction wells, the variation in extraction rates as a function of the change of well locations, and the reliability of the optimal designs. The number of realizations (stack number) that caused the design factors to converge could be determined. Effective stochastic optimization may be achieved by reducing computational resources. An increase in the variability of the conductivity distribution requires more extraction wells. Information about potential extraction wells can be used to prevent failure of the remediation task.
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Optimal groundwater remediation design of a Pump and Treat system considering clean-up time
Geosciences Journal, 2005Co-Authors: Kang-kun Lee, Yunjung HyunAbstract:This study presents the optimal groundwater remediation design using a Pump and Treat method by optimizing the clean-up time, which is a critical factor to determine an optimal remediation design in practical applications. In this study, a simulation-optimization approach was used to determine an optimal remediation design. For a simulation-optimization approach, MODFLOW and MT3D models were used for simulating groundwater flow and mass transport, and the genetic algorithm (GA) was applied for optimizing the number and locations of Pumping wells for applications of the Pump and Treat methods. The optimal remediation design was determined by using two objective functions: minimizing the total Pumping rate and total Pumping volume with optimizing clean-up time, respectively. Results revealed that major Pumping wells were mainly located on the centerline at down-gradient of regional flow regardless of the objective functions. However, the number and locations of optimal Pumping wells varied with time and unnecessarily excessive Pumping occurred when clean-up time was Treated as a fixed constraint. Therefore, it is concluded that clean-up time must be optimized by considering it as a decision variable in order to design the optimal Pump and Treat system. The sensitivity analysis showed that there is an appropriate range of hydraulic conductivity for the practical and effective Pump and Treat remediation design. However, this sensitivity analysis is very limited and model-specific. Thus, the sensitivity of a remediation design to other hydraulic parameters, boundary and initial conditions, and contaminant concentrations should be further investigated.
Sungho Yoon - One of the best experts on this subject based on the ideXlab platform.
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coal tar recovery using enhanced Pump and Treat
Journal of Chemical Technology & Biotechnology, 2013Co-Authors: Konstantinos Kostarelos, Sungho Yoon, Kenneth Y LeeAbstract:BACKGROUND Most experts acknowledge that low aqueous solubility results in low mass recovery rates using Pump-and-Treat (P&T), making such systems ineffective for coal tar (a multi-component NAPL) recovery. It is proposed to increase the apparent aqueous solubility of coal tar by orders of magnitude as an enhancement to conventional P&T schemes (or ‘P&T–E’), increasing coal tar recovery rates, reducing the pore volumes and time required for complete recovery, thus translating into cost savings. RESULTS Batch test results of aqueous solutions containing anionic surfactant, co-solvent, and electrolyte are presented that were studied for both compatibility with a field-obtained coal tar and effectiveness at solubilizing the coal tar above its aqueous solubility. Seven surfactants were tested at room temperature (23C) in aqueous solutions containing the surfactant with co-solvents and electrolytes. The most promising surfactant solution solubilized upwards of 40 000 mg L−1 coal tar. A 1–D column test resulted in 97% recovery using the promising surfactant. CONCLUSIONS P&T–E could significantly increase coal tar solubility without causing the formation of a rate-limiting, solid-like film and offers a promising approach for the remediation of coal tar from the subsurface. © 2013 Society of Chemical Industry
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Coal tar recovery using enhanced ‘Pump‐and‐Treat’
Journal of Chemical Technology & Biotechnology, 2013Co-Authors: Konstantinos Kostarelos, Sungho YoonAbstract:BACKGROUND Most experts acknowledge that low aqueous solubility results in low mass recovery rates using Pump-and-Treat (P&T), making such systems ineffective for coal tar (a multi-component NAPL) recovery. It is proposed to increase the apparent aqueous solubility of coal tar by orders of magnitude as an enhancement to conventional P&T schemes (or ‘P&T–E’), increasing coal tar recovery rates, reducing the pore volumes and time required for complete recovery, thus translating into cost savings. RESULTS Batch test results of aqueous solutions containing anionic surfactant, co-solvent, and electrolyte are presented that were studied for both compatibility with a field-obtained coal tar and effectiveness at solubilizing the coal tar above its aqueous solubility. Seven surfactants were tested at room temperature (23C) in aqueous solutions containing the surfactant with co-solvents and electrolytes. The most promising surfactant solution solubilized upwards of 40 000 mg L−1 coal tar. A 1–D column test resulted in 97% recovery using the promising surfactant. CONCLUSIONS P&T–E could significantly increase coal tar solubility without causing the formation of a rate-limiting, solid-like film and offers a promising approach for the remediation of coal tar from the subsurface. © 2013 Society of Chemical Industry
Min-der Lin - One of the best experts on this subject based on the ideXlab platform.
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Pump-and-Treat ground-water remediation system optimization
Journal of Water Resources Planning and Management, 1996Co-Authors: Daene C. Mckinney, Min-der LinAbstract:A ground-water management model using a nonlinear programming algorithm was developed to find the minimum cost design of the combined Pumping and Treatment components of a Pump-and-Treat remediation system and includes the fixed costs of system construction and installation as well as operation and maintenance. The fixed-cost terms of the objective function are incorporated into the nonlinear programming formulation using a penalty coefficient method. Results of applying the model to an aquifer with homogeneous hydraulic conductivity show that a combined well field and Treatment process model that includes fixed costs has a significant impact on the design and cost of these systems, reducing the cost by using fewer, larger-flow-rate wells. Previous Pump-and-Treat design formulations have resulted in systems with numerous, low-flow-rate wells due to the use of simplified cost functions that do not exhibit economies of scale or fixed costs. Two example aquifers with heterogeneous conductivity fields were al...
