Preliminary results of composite liner field performance study

Othman, Majdi A.; Bonaparte, Rudolph; Gross, Beth A.

doi:10.1016/s0266-1144(98)80008-3

“…In soil mechanics, it is common to employ an idealized description of virgin compression where it is assumed that the void ratio is a linear function of the logarithm of the effective stress [17], i.e. e = e p −C c log p (5) where e p and p are the void ratio and effective stress values, respectively, corresponding to the preconsolidation stress and C c is the compression index of the soil (defined by the absolute value of the slope of the idealized virgin compression line).…”

Section: Constitutive Relationsmentioning

confidence: 99%

“…Despite the widespread use of diffusion only models and a rigid soil, some field data for composite barriers have indicated that the transit time of VOCs is much less than the transit time that can be explained by diffusion alone [5,6]. Furthermore, higher than expected liquid flow rates into secondary leachate collection systems (SLCSs) have been attributed to 'consolidation water' being expelled from the overlying liner [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…The literature reviewed above demonstrates considerable uncertainty as to the effect mechanical consolidation has on contaminant transport through barrier systems, and whether or not it could be responsible for the early breakthrough of contaminants as observed by Othman et al [5] and Workman [6]. Given that this uncertainty can be removed through rigorous analysis, an interesting question that arises is under what circumstances do simplified contaminant transport models commonly used in liner design give conservative predictions of contaminant break through times.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical investigation of the effects of consolidation on contaminant transport through clay barriers

Lewis

¹

,

Pivonka

²

,

Smith

³

2008

Num Anal Meth Geomechanics

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SUMMARYConsolidation of clayey contaminant barriers such as landfill liners has been postulated as a cause of early breakthrough of contaminants. In this paper we theoretically investigate this proposition. For this purpose a sophisticated one-dimensional, large-deformation model of coupled mechanical consolidation and solute transport is employed. This new model is a generalization of existing coupled consolidation and solute transport models described in the literature. It takes into account both non-linearities in geometry as well as constitutive relations. The latter relate the compressibility, hydraulic conductivity and coefficient of effective diffusivity to the deformation of the soil. The model is applied to a case study of a clay liner and geomembrane system. Results obtained from numerical solution of the model equations are compared with those from various simplified models, including a 'diffusion only' (i.e. a rigid soil) model traditionally used in contaminant barrier design. For barriers incorporating low compressibility soils (as for many well compacted clays), there is little difference between contaminant transit (i.e. breakthrough) times predicted by the two models. However, for contaminant barriers incorporating more compressible soils, consolidation is shown to significantly accelerate transport. These results indicate the potential importance of accounting for the effects of soil consolidation and highlight the limitations of existing models when modelling solute transport through composite barriers utilizing soft soils. Based on these limited results, we suggest a possible way of taking into account soil consolidation using simplified models.

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“…Even more recently, the US EPA, recognizing the need for comments, held a workshop in Arlington, VA (Sept. [6][7]2000) on needs and regulatory issues associated with implementation of "controlled" or "bioreactor" landfills. Proceedings of this workshop are promised and should be forthcoming shortly from ERG, Inc, of Lexington, Massachusetts.…”

Section: Epa Workhop On Landfill Bioreactorsmentioning

confidence: 99%

Landfill Operation for Carbon Sequestration and Maximum Methane Emission Control

Augenstein¹

2001

0

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Worldwide, landfill methane emissions are responsible for an estimated 3 to 5% of the total increase in "radiative forcing" due to buildup of all greenhouse gases in earth's atmosphere, in simplified terms, the "greenhouse effect". Controlled landfilling is an approach to manage solid waste landfills, so as to rapidly complete methane generation, while maximizing gas capture and minimizing the usual emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated to more rapid and earlier completion to full potential by improving conditions (principally moisture, but also temperature) to optimize biological processes occurring within the landfill. Gas is contained through use of surface membrane cover. Gas is captured via porous layers, under the cover, operated at slight vacuum. A field demonstration project has been ongoing under NETL sponsorship for the past several years near Davis, CA. Results have been extremely encouraging. Two major benefits of the technology are reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times, more predictably, than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role both in reduction of US greenhouse gas emissions and in US renewable energy. v ACKNOWLEDGMENTS IEM and the authors acknowledge the considerable help and support of the following, and their contributions: Sean Plasynski, of the National Energy Technology Laboratory (NETL) for helpful guidance and consultation throughout this report. Vicky Shears, and also Raymond Jarr, of the Federal Energy Technology Center (FETC) for helpful guidance and consultation on contract issues through this report. John Pacey, for his advice and support in all aspects of the project since its inception. Also for his personal work in enabling the increasing acceptance of this technology.

show abstract

“…Even more recently, the US EPA, recognizing the need for comments, held a workshop in Arlington, VA (Sept. [6][7]2000) on needs and regulatory issues associated with implementation of "controlled" or "bioreactor" landfills. Proceedings of this workshop are promised and should be forthcoming shortly from ERG, Inc, of Lexington, Massachusetts.…”

Section: Epa Workhop On Landfill Bioreactorsmentioning

confidence: 99%

Landfill Operation for Carbon Sequestration and Maximum Methane Emission Control

Augenstein¹,

Yazdani²,

Moore³

et al. 2000

0

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Worldwide, landfill methane emissions are responsible for an estimated 3 to 5% of the total increase in "radiative forcing" due to buildup of all greenhouse gases in earth's atmosphere, in simplified terms, the "greenhouse effect". Controlled landfilling is an approach to manage solid waste landfills, so as to rapidly complete methane generation, while maximizing gas capture and minimizing the usual emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated to more rapid and earlier completion to full potential by improving conditions (principally moisture, but also temperature) to optimize biological processes occurring within the landfill. Gas is contained through use of surface membrane cover. Gas is captured via porous layers, under the cover, operated at slight vacuum. A field demonstration project has been ongoing under NETL sponsorship for the past several years near Davis, CA. Results have been extremely encouraging. Two major benefits of the technology are reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times, more predictably, than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role both in reduction of US greenhouse gas emissions and in US renewable energy.The work described in this report, to demonstrate and advance this technology, has used two demonstration-scale cells of size (8000 metric tons [tonnes]), sufficient to replicate many heat and compaction characteristics of larger "full-scale" landfills. An enhanced demonstration cell has received moisture supplementation to field capacity. This is the maximum moisture waste can hold while still limiting liquid drainage rate to minimal and safely manageable levels. The enhanced landfill module was compared to a parallel control landfill module receiving no moisture additions. Gas recovery has continued for a period of over 4 years. It is quite encouraging that the enhanced cell methane recovery has been close to 10-fold that experienced with conventional landfills. This is the highest methane recovery rate per unit waste, and thus progress toward stabilization, documented anywhere for such a large waste mass. This high recovery rate is attributed to moisture, and elevated temperature attained inexpensively during startup. Economic analyses performed under Phase I of this NETL contract indicate "greenhouse cost effectiveness" to be excellent. Other benefits include substantial waste volume loss (over 30%) which translates to extended landfill life. Other environmental benefits include rapidly improved quality and stabilization (lowered pollutant levels) in liquid leachate which drains from the waste.Under the NETL Phase II, work has also been initiated to scale up and operate a bioreactor landfill on scale of several hundred thousand tons. This "full-scale" bioreactor operatio...

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Preliminary results of composite liner field performance study

Cited by 18 publications

References 1 publication

Theoretical investigation of the effects of consolidation on contaminant transport through clay barriers

Theoretical investigation of the effects of consolidation on contaminant transport through clay barriers

Landfill Operation for Carbon Sequestration and Maximum Methane Emission Control

Landfill Operation for Carbon Sequestration and Maximum Methane Emission Control

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