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Assessment of the spatial variability in leachate migration from an old landfill site
HYDROGEOLOGY:GROUNDWATER Soil venting is a widely used technology for removal of volatile organic compounds from the unsaturated zone. However its efficiency and length of operation is subject to many constraints. The presence of an heterogeneous porous medium is one potential cause of reduced efficiency. A laboratory column study to investigate effect of diffusion between macropore and micropore domains on tracer transport was performed. Dry glass beads and an artificial macropore were used to simulate a structured porous medium. The contribution of hydrodynamic dispersion, axial diffusion, and diffusion between macropore and micropore domains to total tracer dispersion was quantified. Diffusion between macropore and micropore domains was the major contributing process to gas dispersion at gas velocities > 120 cm min "1. (from Authors)
957075 Optimization of pollution plume containment using management models J. Nemecek, J. Myl & M. Nawalany, in: Groundwater
quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 271-278. The applicability of groundwater management modelling is evaluated using field data. The abandoned waste disposal site of a large chemical industrial plant was selected as a pilot study. Several strategies to optimize the containment/control of the groundwater contamination at the site were considered. This optimization was done using two different approaches. Due to specifically unfavourable local conditions it was found that conventional particle tracking gives better results than MODMAN optimization shell. The reason for this is the more restrictive interpretation of constraints in the MODMAN. The consequences for the waste disposal site are discussed leading to the special case of optimization under relaxed constraints. Additionally, the cost of each alternative was assessed and a ranking of suggested containment scenarios is presented. (Authors)
957076 Modelling of complexation of heavy metals by dissolved organic substances and its effects on adsorption and transport in aquifers H. J. Lensing, J. Von Sachs, A. Oberle & B. Herrling, in:
Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 165-172. Dissolved organic substances can act as carriers to enhance the transport of contaminants in groundwater. The transport of cadmium in absence and presence of naturally occurring dissolved organic carbon was evaluated using columns containing defined aquifer material. A multicomponent transport reaction model was conceptualized as follows: for each component the advection-dispersion equation is solved by the transport part of the model. The metal and DOC retention during transport can be described with different first and second order kinetic approaches. Furthermore, two types of retention sites with distinct rates of retention reaction are considered. The kinetics of these reversible reactions are taken into account in the model by time dependent statements of linear, Langmuir or Freundlich equations. The increased Cd mobility observed in the presence of mobile DOC was explained by complex formation in the water phase. This reaction is realized by an instantaneous equilibrium formulation in the model. A two-step method is applied to solve the coupled transport and retention reaction equations. (from Authors)
313A
957077 Field evaluation of leachate recirculation system Hao Chang & P. E. Gagnard, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 355-363. A two-year full scale field leachate recireulation project was conducted at a dosed landfull site in Illinois to evaluate the effectiveness of three leachate distribution systems including a gravel trench system, a gravity well system, and a pressure injection well. Since the landfill refuse is partially saturated, a downhole neutron probe was used to monitor the change in relative moisture content at monitoring locations. A cumulative flow meter and pressure gauge were installed to monitor flow rates and preclude pressure buildup. The study helped determine the most effective way of recycling leachate and enhancing decomposition of refuse. Continuous monitoring of nearby wells and collection sumps also helped delineate the areal influence of leachate inf'fltration. The observed relative moisture content variation both vertically and spatially within the refuse were used to evaluate the effectiveness of the recirculation systems. In addition, operational difficulties were discussed. (Authors) 957078 Assessment of the spatial variability in leachate migration from an old landfill site P. Kjeldsen & 7 others, in: Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 365-373. Investigations of the pollution of groundwater from old landfills have in most cases focused on delineating the pollution plume and only in very few cases on the landf'dl as a source to groundwater pollution. Landfdls often cover large areas. Spatial variations in leachate composition may have great impact on the location of the main pollution plume in the downstream aquifer. Grindsted landfill in Denmark was investigated by sampling leachate beneath the landfill and in groundwater at the borders of the landfill. A pronounced variability in leachate quality and leakage patterns from the landfdl was observed. Also variations in local groundwater flow directions were found. (Authors) 957079 Some views on the effect of different types of barriers in waste deposits B. Grundfelt & L. O. Hoglund, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 347-354. In the past, waste deposits for municipal and industrial wastes have been designed with a short-sighted view of the environmental effects. The consequences of this can be seen at many disposal sites as severe soil and groundwater contamination. The authorities in Sweden and elsewhere are now changing the protection goals to include more long-term aspects discussing the next glaciation as a reasonable time frame for the durability of the retaining capability of a deposit. This paper describes some design and siting strategies and gives views on their long-term behaviour and environmental impacts. (from Authors) 957080 Detection of contaminant transport from damaged sewerage systems and leaky landt'flls M. Eiswirth, H. Hotzl, C. Lazar & G.-P. Merkler, in:
Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 337-346. The migration and fate of contaminants from damaged sewerage systems and leaky landfills have been investigated,
957075 Optimization of pollution plume containment using management models J. Nemecek, J. Myl & M. Nawalany, in: Groundwater
quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 271-278. The applicability of groundwater management modelling is evaluated using field data. The abandoned waste disposal site of a large chemical industrial plant was selected as a pilot study. Several strategies to optimize the containment/control of the groundwater contamination at the site were considered. This optimization was done using two different approaches. Due to specifically unfavourable local conditions it was found that conventional particle tracking gives better results than MODMAN optimization shell. The reason for this is the more restrictive interpretation of constraints in the MODMAN. The consequences for the waste disposal site are discussed leading to the special case of optimization under relaxed constraints. Additionally, the cost of each alternative was assessed and a ranking of suggested containment scenarios is presented. (Authors)
957076 Modelling of complexation of heavy metals by dissolved organic substances and its effects on adsorption and transport in aquifers H. J. Lensing, J. Von Sachs, A. Oberle & B. Herrling, in:
Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 165-172. Dissolved organic substances can act as carriers to enhance the transport of contaminants in groundwater. The transport of cadmium in absence and presence of naturally occurring dissolved organic carbon was evaluated using columns containing defined aquifer material. A multicomponent transport reaction model was conceptualized as follows: for each component the advection-dispersion equation is solved by the transport part of the model. The metal and DOC retention during transport can be described with different first and second order kinetic approaches. Furthermore, two types of retention sites with distinct rates of retention reaction are considered. The kinetics of these reversible reactions are taken into account in the model by time dependent statements of linear, Langmuir or Freundlich equations. The increased Cd mobility observed in the presence of mobile DOC was explained by complex formation in the water phase. This reaction is realized by an instantaneous equilibrium formulation in the model. A two-step method is applied to solve the coupled transport and retention reaction equations. (from Authors)
313A
957077 Field evaluation of leachate recirculation system Hao Chang & P. E. Gagnard, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 355-363. A two-year full scale field leachate recireulation project was conducted at a dosed landfull site in Illinois to evaluate the effectiveness of three leachate distribution systems including a gravel trench system, a gravity well system, and a pressure injection well. Since the landfill refuse is partially saturated, a downhole neutron probe was used to monitor the change in relative moisture content at monitoring locations. A cumulative flow meter and pressure gauge were installed to monitor flow rates and preclude pressure buildup. The study helped determine the most effective way of recycling leachate and enhancing decomposition of refuse. Continuous monitoring of nearby wells and collection sumps also helped delineate the areal influence of leachate inf'fltration. The observed relative moisture content variation both vertically and spatially within the refuse were used to evaluate the effectiveness of the recirculation systems. In addition, operational difficulties were discussed. (Authors) 957078 Assessment of the spatial variability in leachate migration from an old landfill site P. Kjeldsen & 7 others, in: Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 365-373. Investigations of the pollution of groundwater from old landfills have in most cases focused on delineating the pollution plume and only in very few cases on the landf'dl as a source to groundwater pollution. Landfdls often cover large areas. Spatial variations in leachate composition may have great impact on the location of the main pollution plume in the downstream aquifer. Grindsted landfill in Denmark was investigated by sampling leachate beneath the landfill and in groundwater at the borders of the landfill. A pronounced variability in leachate quality and leakage patterns from the landfdl was observed. Also variations in local groundwater flow directions were found. (Authors) 957079 Some views on the effect of different types of barriers in waste deposits B. Grundfelt & L. O. Hoglund, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 347-354. In the past, waste deposits for municipal and industrial wastes have been designed with a short-sighted view of the environmental effects. The consequences of this can be seen at many disposal sites as severe soil and groundwater contamination. The authorities in Sweden and elsewhere are now changing the protection goals to include more long-term aspects discussing the next glaciation as a reasonable time frame for the durability of the retaining capability of a deposit. This paper describes some design and siting strategies and gives views on their long-term behaviour and environmental impacts. (from Authors) 957080 Detection of contaminant transport from damaged sewerage systems and leaky landt'flls M. Eiswirth, H. Hotzl, C. Lazar & G.-P. Merkler, in:
Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 337-346. The migration and fate of contaminants from damaged sewerage systems and leaky landfills have been investigated,