The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) fl... more The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) flow was estimated using a short-term air injection test. Air was added to 134 vertical wells installed at three different depths at flow rates in the range of and the corresponding steady state ...
Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfi... more Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfills is becoming more commonplace. A steady-state one-dimensional analytical landfill gas model was developed to assist in the assessment and design of such collection systems. The ...
The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, in... more The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, infiltration galleries or blankets) for steady state are the rate liquids can be added to the source, the lateral and vertical extents of the zone of impact of the source, and the liquids volume needed to wet the waste within the zone of impact at steady state. This paper presents charts that a designer can use to estimate these key parameters as functions of source dimensions, injection pressure, and municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy) for designing a new or analyzing an existing horizontal source system for liquids addition to landfilled waste. SEEP/W was used to model liquids flow from a horizontal source in a range of conditions practically encountered for such systems. The governing equation (Richard's equation) and the boundary conditions were analyzed to formulate dimensionless variables by normalizing the design parameters (flow rate, injection pressure, the lateral zone of impact, injection pressure, and the added liquids volume) with the waste properties and source dimensions. The simulation results were transformed to the respective dimensionless forms and presented in design charts to estimate the key design parameters as functions of the source dimensions, waste properties, and injection pressure. The presentation of the modeling results in the dimensionless form facilitates their use beyond the conditions modeled. A solved example is presented to demonstrate the use of the design charts. The approach presented in the paper should be considered as approximate and designers should use their judgement and experience when using these charts for designing a horizontal liquids addition system for a specific site.
The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well... more The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well, and the liquids volume needed to wet the waste within the zone of impact of the well are the key inputs needed to design a vertical well system. This paper presents design charts that can be used to estimate these inputs as a function of municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy ratio), well dimensions (radius and screen length), and injection pressure. SEEP/W modeling was conducted to estimate the key design inputs for a range of conditions practically encountered for a vertical well installed in landfilled waste. The flow rate, lateral zone of impact of a well, liquids volume added, and injection pressure were normalized with the waste properties and well dimensions to formulate dimensionless variables. A series of design charts were created to present dimensionless steady-state flow rate, lateral zone of impact, and the dimensionless liquid volume needed to reach a steady-state condition, as a function of dimensionless input variables. By using dimensionless variables formulated for this work, these charts permit the user to estimate the steady-state design variables described above for a wide range of configurations and conditions beyond those simulated without the need for further modeling. The results of the study suggest that the lateral extent of the well can be estimated using Darcy's equation and assuming saturated unit-gradient vertical flow regime below the well bottom. An example problem is presented to illustrate the use of the design charts. The scenario described in the example problem was also modeled with SEEP/W, and the results were compared with those obtained from the design charts to demonstrate the validity of design charts for scenarios other than those used for the development of the design charts. The methodology presented in this paper should be thought of as a means to provide a set of bounds that an engineer can use along with their judgment in the design of a system for a specific site.
Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concent... more Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concentrations of a number of heavy metals. The residue fractions analyzed included a fine fraction (<0.425 mm), an intermediate fraction (>0.425 and <6.3 mm) and a fraction consisting of paper products that could ultimately degrade to a smaller size. The intermediate fraction appeared to be organic in nature, while the fine fraction was more soil-like. In general, the metal concentrations were greatest in the intermediate fraction and lowest in the fine fraction. The effect of sample age on the elemental content was also investigated. The concentrations of several elements were greater in older samples (sample 8 years in age) when compared to newer samples (sample 3 years in age). Limitations associated with the land application of residual soil (composed of the fine and intermediate fractions) were assessed by comparing measured concentrations to regulatory threshold values. In general, most metal concentrations were below regulatory thresholds for use in unrestricted settings. At the concentrations measured, however, several elements might limit reuse options, depending on which regulatory threshold serves as a benchmark. Elevated concentrations of arsenic presented the greatest limitation with respect to common US thresholds while elevated cadmium concentrations presented the greatest limitation when compared to UK thresholds. The source of the arsenic was determined to be the waste, not the cover soil.
This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at... more This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity ͑K s ͒ was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the K s of unsaturated soil. The K s of the landfilled waste was found to range from 5.4ϫ 10 −6 to 6.1ϫ 10 −5 cm/ s. The K s was found to be on the lower end of the range of K s reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values ͑k w ͒ of the landfilled waste calculated based on K s were compared with permeability values estimated using air as the fluid ͑air permeability, k a ͒. Values of k a were found to be approximately three orders of magnitude greater than those of k w . The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as potential clogging of media and short-circuiting of air along the well may also have contributed to the differences in k a and k w .
The ability of resistance-based sensors to measure in situ waste moisture content in a landfill w... more The ability of resistance-based sensors to measure in situ waste moisture content in a landfill was examined. One hundred and thirty-five resistance-based sensors were installed in a leachate recirculation well field at a bioreactor landfill in Florida, US. The performance of these sensors was studied for a period of over 6 years. The sensors were found to respond to an increase in moisture resulting from leachate recirculation. It was observed that 78% of sensors worked successfully in the field during the study period. The initial spatial average moisture content determined by the sensor readings (using a laboratory-derived calibration) was 42.8% compared to 23% from gravimetric readings. Eighteen sensors (13%) showed that they were saturated before liquid addition, and no change in moisture content was observed in these sensors during the study period. Laboratory-derived calibration methods resulted in an over-estimation of moisture content. An alternate field-calibration method, where wetted sensor output was assumed equal to the average of gravimetric measurements for wet samples, was evaluated. The final spatial average moisture contents were 64.2% and 44.4% for the laboratory-derived and field-derived calibration methodologies, respectively, compared to 45% measured gravimetrically from excavated waste samples. When moisture content was determined using a mass balance approach, the result was 34.6%. The results suggest that when appropriately calibrated, resistivity-based sensors can be used to obtain a reasonably accurate estimate of local moisture content. However, caution should be taken to extend the moisture content values that are representative of waste surrounding the sensors to estimate the overall moisture content on the landfill-wide scale.
The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) fl... more The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) flow was estimated using a short-term air injection test. Air was added to 134 vertical wells installed at three different depths at flow rates in the range of and the corresponding steady state ...
Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfi... more Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfills is becoming more commonplace. A steady-state one-dimensional analytical landfill gas model was developed to assist in the assessment and design of such collection systems. The ...
The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, in... more The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, infiltration galleries or blankets) for steady state are the rate liquids can be added to the source, the lateral and vertical extents of the zone of impact of the source, and the liquids volume needed to wet the waste within the zone of impact at steady state. This paper presents charts that a designer can use to estimate these key parameters as functions of source dimensions, injection pressure, and municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy) for designing a new or analyzing an existing horizontal source system for liquids addition to landfilled waste. SEEP/W was used to model liquids flow from a horizontal source in a range of conditions practically encountered for such systems. The governing equation (Richard&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s equation) and the boundary conditions were analyzed to formulate dimensionless variables by normalizing the design parameters (flow rate, injection pressure, the lateral zone of impact, injection pressure, and the added liquids volume) with the waste properties and source dimensions. The simulation results were transformed to the respective dimensionless forms and presented in design charts to estimate the key design parameters as functions of the source dimensions, waste properties, and injection pressure. The presentation of the modeling results in the dimensionless form facilitates their use beyond the conditions modeled. A solved example is presented to demonstrate the use of the design charts. The approach presented in the paper should be considered as approximate and designers should use their judgement and experience when using these charts for designing a horizontal liquids addition system for a specific site.
The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well... more The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well, and the liquids volume needed to wet the waste within the zone of impact of the well are the key inputs needed to design a vertical well system. This paper presents design charts that can be used to estimate these inputs as a function of municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy ratio), well dimensions (radius and screen length), and injection pressure. SEEP/W modeling was conducted to estimate the key design inputs for a range of conditions practically encountered for a vertical well installed in landfilled waste. The flow rate, lateral zone of impact of a well, liquids volume added, and injection pressure were normalized with the waste properties and well dimensions to formulate dimensionless variables. A series of design charts were created to present dimensionless steady-state flow rate, lateral zone of impact, and the dimensionless liquid volume needed to reach a steady-state condition, as a function of dimensionless input variables. By using dimensionless variables formulated for this work, these charts permit the user to estimate the steady-state design variables described above for a wide range of configurations and conditions beyond those simulated without the need for further modeling. The results of the study suggest that the lateral extent of the well can be estimated using Darcy's equation and assuming saturated unit-gradient vertical flow regime below the well bottom. An example problem is presented to illustrate the use of the design charts. The scenario described in the example problem was also modeled with SEEP/W, and the results were compared with those obtained from the design charts to demonstrate the validity of design charts for scenarios other than those used for the development of the design charts. The methodology presented in this paper should be thought of as a means to provide a set of bounds that an engineer can use along with their judgment in the design of a system for a specific site.
Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concent... more Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concentrations of a number of heavy metals. The residue fractions analyzed included a fine fraction (<0.425 mm), an intermediate fraction (>0.425 and <6.3 mm) and a fraction consisting of paper products that could ultimately degrade to a smaller size. The intermediate fraction appeared to be organic in nature, while the fine fraction was more soil-like. In general, the metal concentrations were greatest in the intermediate fraction and lowest in the fine fraction. The effect of sample age on the elemental content was also investigated. The concentrations of several elements were greater in older samples (sample 8 years in age) when compared to newer samples (sample 3 years in age). Limitations associated with the land application of residual soil (composed of the fine and intermediate fractions) were assessed by comparing measured concentrations to regulatory threshold values. In general, most metal concentrations were below regulatory thresholds for use in unrestricted settings. At the concentrations measured, however, several elements might limit reuse options, depending on which regulatory threshold serves as a benchmark. Elevated concentrations of arsenic presented the greatest limitation with respect to common US thresholds while elevated cadmium concentrations presented the greatest limitation when compared to UK thresholds. The source of the arsenic was determined to be the waste, not the cover soil.
This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at... more This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity ͑K s ͒ was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the K s of unsaturated soil. The K s of the landfilled waste was found to range from 5.4ϫ 10 −6 to 6.1ϫ 10 −5 cm/ s. The K s was found to be on the lower end of the range of K s reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values ͑k w ͒ of the landfilled waste calculated based on K s were compared with permeability values estimated using air as the fluid ͑air permeability, k a ͒. Values of k a were found to be approximately three orders of magnitude greater than those of k w . The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as potential clogging of media and short-circuiting of air along the well may also have contributed to the differences in k a and k w .
The ability of resistance-based sensors to measure in situ waste moisture content in a landfill w... more The ability of resistance-based sensors to measure in situ waste moisture content in a landfill was examined. One hundred and thirty-five resistance-based sensors were installed in a leachate recirculation well field at a bioreactor landfill in Florida, US. The performance of these sensors was studied for a period of over 6 years. The sensors were found to respond to an increase in moisture resulting from leachate recirculation. It was observed that 78% of sensors worked successfully in the field during the study period. The initial spatial average moisture content determined by the sensor readings (using a laboratory-derived calibration) was 42.8% compared to 23% from gravimetric readings. Eighteen sensors (13%) showed that they were saturated before liquid addition, and no change in moisture content was observed in these sensors during the study period. Laboratory-derived calibration methods resulted in an over-estimation of moisture content. An alternate field-calibration method, where wetted sensor output was assumed equal to the average of gravimetric measurements for wet samples, was evaluated. The final spatial average moisture contents were 64.2% and 44.4% for the laboratory-derived and field-derived calibration methodologies, respectively, compared to 45% measured gravimetrically from excavated waste samples. When moisture content was determined using a mass balance approach, the result was 34.6%. The results suggest that when appropriately calibrated, resistivity-based sensors can be used to obtain a reasonably accurate estimate of local moisture content. However, caution should be taken to extend the moisture content values that are representative of waste surrounding the sensors to estimate the overall moisture content on the landfill-wide scale.
The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) fl... more The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) flow was estimated using a short-term air injection test. Air was added to 134 vertical wells installed at three different depths at flow rates in the range of and the corresponding steady state ...
Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfi... more Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfills is becoming more commonplace. A steady-state one-dimensional analytical landfill gas model was developed to assist in the assessment and design of such collection systems. The ...
The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, in... more The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, infiltration galleries or blankets) for steady state are the rate liquids can be added to the source, the lateral and vertical extents of the zone of impact of the source, and the liquids volume needed to wet the waste within the zone of impact at steady state. This paper presents charts that a designer can use to estimate these key parameters as functions of source dimensions, injection pressure, and municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy) for designing a new or analyzing an existing horizontal source system for liquids addition to landfilled waste. SEEP/W was used to model liquids flow from a horizontal source in a range of conditions practically encountered for such systems. The governing equation (Richard&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s equation) and the boundary conditions were analyzed to formulate dimensionless variables by normalizing the design parameters (flow rate, injection pressure, the lateral zone of impact, injection pressure, and the added liquids volume) with the waste properties and source dimensions. The simulation results were transformed to the respective dimensionless forms and presented in design charts to estimate the key design parameters as functions of the source dimensions, waste properties, and injection pressure. The presentation of the modeling results in the dimensionless form facilitates their use beyond the conditions modeled. A solved example is presented to demonstrate the use of the design charts. The approach presented in the paper should be considered as approximate and designers should use their judgement and experience when using these charts for designing a horizontal liquids addition system for a specific site.
The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well... more The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well, and the liquids volume needed to wet the waste within the zone of impact of the well are the key inputs needed to design a vertical well system. This paper presents design charts that can be used to estimate these inputs as a function of municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy ratio), well dimensions (radius and screen length), and injection pressure. SEEP/W modeling was conducted to estimate the key design inputs for a range of conditions practically encountered for a vertical well installed in landfilled waste. The flow rate, lateral zone of impact of a well, liquids volume added, and injection pressure were normalized with the waste properties and well dimensions to formulate dimensionless variables. A series of design charts were created to present dimensionless steady-state flow rate, lateral zone of impact, and the dimensionless liquid volume needed to reach a steady-state condition, as a function of dimensionless input variables. By using dimensionless variables formulated for this work, these charts permit the user to estimate the steady-state design variables described above for a wide range of configurations and conditions beyond those simulated without the need for further modeling. The results of the study suggest that the lateral extent of the well can be estimated using Darcy's equation and assuming saturated unit-gradient vertical flow regime below the well bottom. An example problem is presented to illustrate the use of the design charts. The scenario described in the example problem was also modeled with SEEP/W, and the results were compared with those obtained from the design charts to demonstrate the validity of design charts for scenarios other than those used for the development of the design charts. The methodology presented in this paper should be thought of as a means to provide a set of bounds that an engineer can use along with their judgment in the design of a system for a specific site.
Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concent... more Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concentrations of a number of heavy metals. The residue fractions analyzed included a fine fraction (<0.425 mm), an intermediate fraction (>0.425 and <6.3 mm) and a fraction consisting of paper products that could ultimately degrade to a smaller size. The intermediate fraction appeared to be organic in nature, while the fine fraction was more soil-like. In general, the metal concentrations were greatest in the intermediate fraction and lowest in the fine fraction. The effect of sample age on the elemental content was also investigated. The concentrations of several elements were greater in older samples (sample 8 years in age) when compared to newer samples (sample 3 years in age). Limitations associated with the land application of residual soil (composed of the fine and intermediate fractions) were assessed by comparing measured concentrations to regulatory threshold values. In general, most metal concentrations were below regulatory thresholds for use in unrestricted settings. At the concentrations measured, however, several elements might limit reuse options, depending on which regulatory threshold serves as a benchmark. Elevated concentrations of arsenic presented the greatest limitation with respect to common US thresholds while elevated cadmium concentrations presented the greatest limitation when compared to UK thresholds. The source of the arsenic was determined to be the waste, not the cover soil.
This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at... more This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity ͑K s ͒ was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the K s of unsaturated soil. The K s of the landfilled waste was found to range from 5.4ϫ 10 −6 to 6.1ϫ 10 −5 cm/ s. The K s was found to be on the lower end of the range of K s reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values ͑k w ͒ of the landfilled waste calculated based on K s were compared with permeability values estimated using air as the fluid ͑air permeability, k a ͒. Values of k a were found to be approximately three orders of magnitude greater than those of k w . The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as potential clogging of media and short-circuiting of air along the well may also have contributed to the differences in k a and k w .
The ability of resistance-based sensors to measure in situ waste moisture content in a landfill w... more The ability of resistance-based sensors to measure in situ waste moisture content in a landfill was examined. One hundred and thirty-five resistance-based sensors were installed in a leachate recirculation well field at a bioreactor landfill in Florida, US. The performance of these sensors was studied for a period of over 6 years. The sensors were found to respond to an increase in moisture resulting from leachate recirculation. It was observed that 78% of sensors worked successfully in the field during the study period. The initial spatial average moisture content determined by the sensor readings (using a laboratory-derived calibration) was 42.8% compared to 23% from gravimetric readings. Eighteen sensors (13%) showed that they were saturated before liquid addition, and no change in moisture content was observed in these sensors during the study period. Laboratory-derived calibration methods resulted in an over-estimation of moisture content. An alternate field-calibration method, where wetted sensor output was assumed equal to the average of gravimetric measurements for wet samples, was evaluated. The final spatial average moisture contents were 64.2% and 44.4% for the laboratory-derived and field-derived calibration methodologies, respectively, compared to 45% measured gravimetrically from excavated waste samples. When moisture content was determined using a mass balance approach, the result was 34.6%. The results suggest that when appropriately calibrated, resistivity-based sensors can be used to obtain a reasonably accurate estimate of local moisture content. However, caution should be taken to extend the moisture content values that are representative of waste surrounding the sensors to estimate the overall moisture content on the landfill-wide scale.
The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) fl... more The permeability of compacted municipal solid waste in a landfill with respect to air (or gas) flow was estimated using a short-term air injection test. Air was added to 134 vertical wells installed at three different depths at flow rates in the range of and the corresponding steady state ...
Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfi... more Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfills is becoming more commonplace. A steady-state one-dimensional analytical landfill gas model was developed to assist in the assessment and design of such collection systems. The ...
The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, in... more The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, infiltration galleries or blankets) for steady state are the rate liquids can be added to the source, the lateral and vertical extents of the zone of impact of the source, and the liquids volume needed to wet the waste within the zone of impact at steady state. This paper presents charts that a designer can use to estimate these key parameters as functions of source dimensions, injection pressure, and municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy) for designing a new or analyzing an existing horizontal source system for liquids addition to landfilled waste. SEEP/W was used to model liquids flow from a horizontal source in a range of conditions practically encountered for such systems. The governing equation (Richard&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s equation) and the boundary conditions were analyzed to formulate dimensionless variables by normalizing the design parameters (flow rate, injection pressure, the lateral zone of impact, injection pressure, and the added liquids volume) with the waste properties and source dimensions. The simulation results were transformed to the respective dimensionless forms and presented in design charts to estimate the key design parameters as functions of the source dimensions, waste properties, and injection pressure. The presentation of the modeling results in the dimensionless form facilitates their use beyond the conditions modeled. A solved example is presented to demonstrate the use of the design charts. The approach presented in the paper should be considered as approximate and designers should use their judgement and experience when using these charts for designing a horizontal liquids addition system for a specific site.
The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well... more The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well, and the liquids volume needed to wet the waste within the zone of impact of the well are the key inputs needed to design a vertical well system. This paper presents design charts that can be used to estimate these inputs as a function of municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy ratio), well dimensions (radius and screen length), and injection pressure. SEEP/W modeling was conducted to estimate the key design inputs for a range of conditions practically encountered for a vertical well installed in landfilled waste. The flow rate, lateral zone of impact of a well, liquids volume added, and injection pressure were normalized with the waste properties and well dimensions to formulate dimensionless variables. A series of design charts were created to present dimensionless steady-state flow rate, lateral zone of impact, and the dimensionless liquid volume needed to reach a steady-state condition, as a function of dimensionless input variables. By using dimensionless variables formulated for this work, these charts permit the user to estimate the steady-state design variables described above for a wide range of configurations and conditions beyond those simulated without the need for further modeling. The results of the study suggest that the lateral extent of the well can be estimated using Darcy's equation and assuming saturated unit-gradient vertical flow regime below the well bottom. An example problem is presented to illustrate the use of the design charts. The scenario described in the example problem was also modeled with SEEP/W, and the results were compared with those obtained from the design charts to demonstrate the validity of design charts for scenarios other than those used for the development of the design charts. The methodology presented in this paper should be thought of as a means to provide a set of bounds that an engineer can use along with their judgment in the design of a system for a specific site.
Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concent... more Residues reclaimed from a municipal solid waste (MSW) landfill were characterized for the concentrations of a number of heavy metals. The residue fractions analyzed included a fine fraction (<0.425 mm), an intermediate fraction (>0.425 and <6.3 mm) and a fraction consisting of paper products that could ultimately degrade to a smaller size. The intermediate fraction appeared to be organic in nature, while the fine fraction was more soil-like. In general, the metal concentrations were greatest in the intermediate fraction and lowest in the fine fraction. The effect of sample age on the elemental content was also investigated. The concentrations of several elements were greater in older samples (sample 8 years in age) when compared to newer samples (sample 3 years in age). Limitations associated with the land application of residual soil (composed of the fine and intermediate fractions) were assessed by comparing measured concentrations to regulatory threshold values. In general, most metal concentrations were below regulatory thresholds for use in unrestricted settings. At the concentrations measured, however, several elements might limit reuse options, depending on which regulatory threshold serves as a benchmark. Elevated concentrations of arsenic presented the greatest limitation with respect to common US thresholds while elevated cadmium concentrations presented the greatest limitation when compared to UK thresholds. The source of the arsenic was determined to be the waste, not the cover soil.
This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at... more This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity ͑K s ͒ was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the K s of unsaturated soil. The K s of the landfilled waste was found to range from 5.4ϫ 10 −6 to 6.1ϫ 10 −5 cm/ s. The K s was found to be on the lower end of the range of K s reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values ͑k w ͒ of the landfilled waste calculated based on K s were compared with permeability values estimated using air as the fluid ͑air permeability, k a ͒. Values of k a were found to be approximately three orders of magnitude greater than those of k w . The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as potential clogging of media and short-circuiting of air along the well may also have contributed to the differences in k a and k w .
The ability of resistance-based sensors to measure in situ waste moisture content in a landfill w... more The ability of resistance-based sensors to measure in situ waste moisture content in a landfill was examined. One hundred and thirty-five resistance-based sensors were installed in a leachate recirculation well field at a bioreactor landfill in Florida, US. The performance of these sensors was studied for a period of over 6 years. The sensors were found to respond to an increase in moisture resulting from leachate recirculation. It was observed that 78% of sensors worked successfully in the field during the study period. The initial spatial average moisture content determined by the sensor readings (using a laboratory-derived calibration) was 42.8% compared to 23% from gravimetric readings. Eighteen sensors (13%) showed that they were saturated before liquid addition, and no change in moisture content was observed in these sensors during the study period. Laboratory-derived calibration methods resulted in an over-estimation of moisture content. An alternate field-calibration method, where wetted sensor output was assumed equal to the average of gravimetric measurements for wet samples, was evaluated. The final spatial average moisture contents were 64.2% and 44.4% for the laboratory-derived and field-derived calibration methodologies, respectively, compared to 45% measured gravimetrically from excavated waste samples. When moisture content was determined using a mass balance approach, the result was 34.6%. The results suggest that when appropriately calibrated, resistivity-based sensors can be used to obtain a reasonably accurate estimate of local moisture content. However, caution should be taken to extend the moisture content values that are representative of waste surrounding the sensors to estimate the overall moisture content on the landfill-wide scale.
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Papers by Pradeep Jain