As U.S. landfills continue to grow in size, concerns about odorous gas emissions from landfills are increasing. For states that are expanding in population, such as Florida, odors from landfills are a major concern because new housing developments, needed to accommodate the rapid population growth, are creeping closer and closer to the existing landfills. As homes get closer to landfills, odor complaints are likely to become more frequent, causing landfill managers increased problems with public interactions. Odor buffer zones around landfills need to be established to give municipalities tools to help prevent the building of future homes too close to landfills. Using the latest air dispersion model, AERMOD, research predicted downwind odor concentrations from a Central Florida landfill. Accurate estimates of methane emissions throughout a Central Florida landfill were determined using a new technique developed as part of this research that uses hundreds of ambient air VOC measurements taken within a landfill, as receptors. Hundreds of point sources were placed on the landfill, and the standard Gaussian dispersion equations were solved by matrix inversion methods. The methane emission rates were then used as surrogates for odor emissions to predict downwind odor concentrations via AERMOD. By determining a critical zone around a landfill with regards to odor, stakeholders will be able to meet regulatory issues and assist their communities. Other beneficial uses from this research include: determination of existing gas collection system efficiencies, calculation of fugitive greenhouse gas emissions from municipal solid waste (MSW) landfills, and improved landfill gas management.

A laboratory test program was conducted to investigate the effects of temperature, solution strength, and applied stress over increasing conditioning durations on cation exchange processes in sodium bentonite (Na-B) geosynthetic clay liners (GCLs). The test program was intended to determine if the variables of temperature, solution strength, and applied stress had beneficial or detrimental effects on the engineering behavior of Na-B GCLs in municipal solid waste (MSW) landfills and laboratory testing applications. Needlepunched-reinforced, double non-woven Na-B GCL specimens were conditioned in fluids of increasing ionic strength (DI water, 2 mM CaCl2, 50 mM CaCl2, and 200 mM CaCl2 representing control, pore water, mild MSW leachate, and harsh MSW leachate, respectively), temperatures of 5 degrees C, 20 degrees C, 40 degrees C, and 60 degrees C, and overburden stresses (30 kPa and 500 kPa representing stresses experienced by cover and bottom liner systems, respectively) which are all representative of geoenvironmental conditions observed in MSW landfill barrier systems. Cation exchange in the bentonite component of all conditioned Na-B GCL specimens was quantified by measuring the bound cation (BC) complexes and cation exchange capacities (CEC) of the specimens using inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis and by conducting index tests to determine the dimensional characteristics, swell index, and gravimetric moisture content of the specimens. For zero stress conditions, periodic measurements of electrical conductivity, total dissolved solids, sodium and calcium cation concentration, and temperature of the conditioning fluids were recorded to supplement bound cation complex data. For applied stress conditions, electrical conductivity, total dissolved solids, and temperature of the conditioning fluid were recorded. For zero stress conditions, 152 mm x 152 mm Na-B GCL specimens were conditioned in all conditioning fluids and temperatures over increasing time durations ranging from 4 hours to 32 days. For applied stress conditions, 60-mm-diameter Na-B GCL specimens were conditioned in 50 mM CaCl2 conditioning fluid at all temperatures for 4 to 16 days under the applied overburden stresses of 30 kPa and 500 kPa. Temperature, solution strength, and applied stress were all observed to affect cation exchange in the bentonite component of Na-B GCLs. Cation exchange processes were observed to increase with increasing temperature, increasing solution strength, and decreasing applied overburden stress. The majority of cation exchange processes were observed to occur within 8 to 10 days for specimens conditioned under zero stress. Cation exchange processes were observed to have a higher sensitivity to changes in solution strength (up to 625% increase in the change of Na+ BC from DI water to 200 mM CaCl2) compared to changes in temperature (up to 52% increase in the change of Na+ BC from 5 degrees C to 60 degrees C) in zero stress conditions. Changes in the bound cations of the Na-B GCL specimens over time were not reflected in the periodic electrical conductivity measurements taken of the high strength conditioning fluids. The results of this study can be used for quality assurance evaluations of in-service GCLs using thresholds developed for index properties. From the numerical thresholds determined in this study, hydrated Na-B GCL specimens sampled from the field conditioned under zero stress that exhibit swell indices greater than or equal to approximately 70% of the swell index reported by the manufacturer and gravimetric moisture contents of greater than or equal to approximately 200% will likely exhibit adequate hydraulic barrier performance. Hydrated Na-B GCL specimens sampled from the field conditioned under zero stress that exhibit swell indices of less than or equal to approximately 20% of the swell index reported by the manufacturer and gravimetric moisture contents of less than or equal to approximately 100% will likely exhibit inadequate hydraulic barrier performance. The Na-B GCL component of cover liner systems may be susceptible to high rates of cation exchange due to experiencing low overburden stress and elevated temperatures compared to typical earth temperatures. The Na-B GCL component of bottom liner systems may exhibit low rates of cation exchange due to experiencing high overburden stress and cooler temperatures.

Dumping of municipal solid waste (MSW) generated due to anthropogenic activities in any barren land or out fields causes severe hazards to human populations, ecosystems and the environment. In order to avoid this, it is required to design landfills in an engineered and scientific manner. Therefore, it is necessary to understand the behaviour of landfills over a period of time, to design landfills for site specific conditions. In this thesis such an attempt is made to evaluate performance of conventional landfill system using a large scale anaerobic reactor in the laboratory. The performance of the containment (bottom liner and final cover) systems is evaluated through numerical modelling and reliability based analysis. Response Surface Methodology (RSM) is used to develop linear regression models. Influence of various parameters and their uncertainty on the reliability of the containment systems are studied for various scenarios and conditions. Reliability assessment of containment systems play a decisive role in taking remedial measures in order to reduce its adverse affects on the environment and human health in the vicinity of landfill sites. On the other hand, pre-assessment of risk guides the engineers, planners and decision makers in achieving the goal of sustainable solid waste management as well as safe landfills. The thesis also includes assessment of vulnerability of groundwater to contamination, identification and ranking of suitable sites for municipal solid waste (MSW) disposal in the Bengaluru district, using remote sensing and Geographic information system (GIS) integrated with analytical hierarchy process (AHP), a multi criteria decision making tool. The study considers various land use, geological, hydrogeological and environmental factors as criteria. As a result, two most suitable locations are identified around the Bengaluru city and their descriptions are provided. Further, reliability analysis of the suitability of sites is evaluated considering criteria as random variables. The proposed reliability based approach helps the decision makers and planners to choose site locations having low probability of environmental pollution. The provided methods in the thesis can be effectively used for engineered design of landfills.