Choi Chi Yuen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 146-159). / Abstracts in English and Chinese. / Abstract / Acknowledgement / Contents / List of Figures / List of Tables / List of Plates / List of Appendices / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Landfilling --- p.1 / Chapter 1.1.1 --- Definition --- p.1 / Chapter 1.1.2 --- Waste decomposition process --- p.2 / Chapter 1.1.3 --- Major principles of landfill design --- p.7 / Chapter 1.1.4 --- General practices after the completion of landfill --- p.10 / Chapter 1.1.4.1 --- Surface capping --- p.10 / Chapter 1.1.4.2 --- Revegetation --- p.10 / Chapter 1.1.4.3 --- Post-closure management --- p.14 / Chapter 1.1.4.4 --- End use --- p.15 / Chapter 1.2 --- Post-closure landfill problems --- p.15 / Chapter 1.2.1 --- Subsidence and soil compaction --- p.15 / Chapter 1.2.2 --- Vegetation establishment --- p.16 / Chapter 1.2.3 --- Soil quality and thickness --- p.17 / Chapter 1.2.4 --- Adverse landfill factors --- p.22 / Chapter 1.3 --- Landfill ecology --- p.23 / Chapter 1.3.1 --- Soil-plant ecosystem on completed landfills --- p.23 / Chapter 1.3.2 --- Landfill soil fauna --- p.24 / Chapter 1.3.3 --- Landfill soil microbes --- p.25 / Chapter 1.3.4 --- Ecosystem integral development --- p.26 / Chapter 1.4 --- Succession management --- p.28 / Chapter 1.5 --- Objectives of the study --- p.32 / Chapter Chapter 2 --- Comparative Study of Landfills in Hong Kong / Chapter 2.1 --- Introduction --- p.34 / Chapter 2.2 --- Materials and Methods --- p.36 / Chapter 2.2.1 --- Site selection --- p.36 / Chapter 2.2.2 --- Soil characteristics --- p.39 / Chapter 2.2.2.1 --- Field measurement --- p.39 / Chapter 2.2.2.2 --- Soil sampling and laboratory analysis --- p.40 / Chapter 2.2.3 --- Vegetation characteristics --- p.42 / Chapter 2.2.3.1 --- Coverage of trees and understorey vegetation --- p.42 / Chapter 2.2.3.2 --- Coverage of individual plant species --- p.42 / Chapter 2.2.4 --- Calculation of representative plant score --- p.42 / Chapter 2.2.5 --- Statistical analyses --- p.44 / Chapter 2.3 --- Results and Discussion --- p.44 / Chapter 2.3.1 --- General properties of the cover soil on completed landfills --- p.44 / Chapter 2.3.2 --- Landfill categorization based on edaphic properties --- p.48 / Chapter 2.3.3 --- Vegetation coverage on completed landfills --- p.55 / Chapter 2.3.4 --- Vegetation characteristics on completed landfills --- p.59 / Chapter 2.4 --- Conclusions --- p.65 / Chapter Chapter 3 --- Vegetation Performance on Selected Landfills / Chapter 3.1 --- Introduction --- p.68 / Chapter 3.2 --- Materials and Methods --- p.70 / Chapter 3.2.1 --- Vegetation analysis --- p.70 / Chapter 3.2.2 --- Vegetation descriptions --- p.71 / Chapter 3.3 --- Results and Discussion --- p.73 / Chapter 3.3.1 --- General description of the vegetation --- p.73 / Chapter 3.3.2 --- Vegetation structure and diversity --- p.73 / Chapter 3.3.3 --- The most successful and important plant species --- p.86 / Chapter 3.3.4 --- Revegetation success --- p.91 / Chapter 3.4 --- Conclusions --- p.95 / Chapter Chapter 4 --- Diversity and Population of Soil Invertebrates on Selected Landfills / Chapter 4.1 --- Introduction --- p.99 / Chapter 4.2 --- Materials and Methods --- p.100 / Chapter 4.2.1 --- Diversities of soil and litter invertebrates --- p.100 / Chapter 4.2.1.1 --- Soil and litter sampling --- p.100 / Chapter 4.2.1.2 --- Soil animal extraction --- p.101 / Chapter 4.2.2 --- Statistical analysis --- p.101 / Chapter 4.3 --- Results and Discussion --- p.103 / Chapter 4.3.1 --- General description of the soil invertebrates --- p.103 / Chapter 4.3.2 --- Dominant soil invertebrates --- p.107 / Chapter 4.3.3 --- Soil macroarthropods --- p.109 / Chapter 4.3.4 --- Other soil invertebrates --- p.112 / Chapter 4.3.5 --- General description of litter invertebrates and its implication --- p.113 / Chapter 4.3.6 --- Diversity of the soil and litter fauna and the ecosystem development --- p.117 / Chapter 4.4 --- Conclusions --- p.119 / Chapter Chapter 5 --- Microbial Performance on Selected Landfills / Chapter 5.1 --- Introduction --- p.121 / Chapter 5.2 --- Materials and Methods --- p.123 / Chapter 5.2.1 --- Soil sampling --- p.123 / Chapter 5.2.2 --- Microbial analyses --- p.123 / Chapter 5.2.2.1 --- Plate-count methods for microbial abundance --- p.123 / Chapter 5.2.2.2 --- ATP bioluminescence assay for microbial biomass --- p.124 / Chapter 5.2.2.3 --- Dehydrogenase activity measurement for microbial activity --- p.125 / Chapter 5.2.3 --- Soil analyses --- p.125 / Chapter 5.2.4 --- Statistical analyses --- p.126 / Chapter 5.3 --- Results and Discussion --- p.126 / Chapter 5.3.1 --- The effect of soil quality on microbial population --- p.126 / Chapter 5.3.2 --- Relationship between the faunal and microbial populations --- p.128 / Chapter 5.3.3 --- Microbial diversity of cover soil of the completed landfills --- p.131 / Chapter 5.3.4 --- Microbial biomass of cover soil of the completed landfills --- p.132 / Chapter 5.3.5 --- General microbial activity of cover soil of the completed landfills --- p.137 / Chapter 5.4 --- Conclusions --- p.137 / Chapter Chapter 6 --- General Conclusions --- p.141 / References --- p.146 / Appendices

The body of work presented in this Thesis document provides a comprehensive examination of final cover design for municipal solid waste landfills. Accompanying general design principals is the investigation and resulting recommendations for issues specific to the closure of the Vancouver Landfill. The first objective of the Thesis was to develop a set of physical characteristics for soil materials, which would allow for the construction of a lowpermeability barrier layer meeting British Columbia guidelines. The second objective was to then use the developed soil criteria to evaluate the suitability of Lower Mainland soils. The physical characteristic of soil material, originating from trench excavations in Vancouver, was closely examined and the material evaluated for use in all layers of final cover design. The last objective of the Thesis was to investigate the use of alternative cover materials, including geosynthetics, in final cover design. The combination of a comprehensive literature review and the implementation of a program of soil sample collection and analysis allowed for the completion of the above objectives. Testing of soil samples included the determination of the grain size distribution to the clay fraction level. The major findings of the work are that soil sources in the City of Vancouver are not suitable for use in the construction of a low-permeability barrier layer. Suitable soil sources however, can be found in areas of Surrey and Langley. Trench excavation soil is recommended for use in the foundation layer of the final cover. Lastly, geosynthetic materials are a viable alternative to the use of soil in final cover design. A polyvinyl chloride (PVC) geomembrane would be the most suitable geosynthetic based barrier layer for the requirements of the Vancouver Landfill.

The body of work presented in this Thesis document provides a comprehensive examination of final cover design for municipal solid waste landfills. Accompanying general design principals is the investigation and resulting recommendations for issues specific to the closure of the Vancouver Landfill. The first objective of the Thesis was to develop a set of physical characteristics for soil materials, which would allow for the construction of a lowpermeability barrier layer meeting British Columbia guidelines. The second objective was to then use the developed soil criteria to evaluate the suitability of Lower Mainland soils. The physical characteristic of soil material, originating from trench excavations in Vancouver, was closely examined and the material evaluated for use in all layers of final cover design. The last objective of the Thesis was to investigate the use of alternative cover materials, including geosynthetics, in final cover design. The combination of a comprehensive literature review and the implementation of a program of soil sample collection and analysis allowed for the completion of the above objectives. Testing of soil samples included the determination of the grain size distribution to the clay fraction level. The major findings of the work are that soil sources in the City of Vancouver are not suitable for use in the construction of a low-permeability barrier layer. Suitable soil sources however, can be found in areas of Surrey and Langley. Trench excavation soil is recommended for use in the foundation layer of the final cover. Lastly, geosynthetic materials are a viable alternative to the use of soil in final cover design. A polyvinyl chloride (PVC) geomembrane would be the most suitable geosynthetic based barrier layer for the requirements of the Vancouver Landfill. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate