Date of Award
1989
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
Sanitary landfilling remains a viable alternative for disposal of the ever increasing volumes of municipal solid waste. Current landfill design practice requires the presence of a clay barrier (liner) that may consist of either a natural stratum or compacted clay borrow. The liner acts as a hydraulic barrier to control the flux of contaminants from the waste into the adjacent groundwater. In order to do this clay liners are required to have low hydraulic conductivity, k (typically 10{dollar}\sp{lcub}-8{rcub}{dollar} cm/s) that shall not increase during exposure to waste leachate.;This thesis reports the assessment of compatibility between natural clays from Sarnia, Ontario, and various leachates ranging from municipal solid waste leachate to concentrated organic solvents. The studies were performed using specially designed fixed-ring permeameters that allowed controlling confining effective stresses, volume changes in the soil specimen and chemistry of the influent and effluent permeants.;The Sarnia clays appeared to be compatible with domestic waste leachate, showing slight reductions in k. Extensive retardation of potassium from the leachate required long testing periods (up to twelve pore volumes) before the soils were deemed to be in chemical equilibrium.;Concentrated, water-soluble organics (ethanol and dioxane) increased the hydraulic conductivity of compacted clays by 100 to 1000-fold, thus destroying their effectiveness as liners. Water-compacted clays appeared remarkably resistant to penetration by concentrated hydrophobic solvents such as cyclohexane. Large hydraulic gradients (up to {dollar}\sim{dollar}900) were required to produce breakthrough along compaction induced fractures. However, alcohols and surfactants can facilitate the entry of hydrophobic liquids into the double layers causing large increased in k.;Ethanol and dioxane present in domestic waste leachate at concentrations greater than 70%, produced large increases in k that could be prevented by the application of adequate confining stresses. At organic contents below 70% significant decreases in k took place due to increases in viscosity of the aqueous mixtures. The results are discussed in terms of intrinsic permeability, K, which remained unchanged after permeation of leachate containing up to 70% ethanol or dioxane, suggesting exclusion of less polar liquids from the water-saturated double layers.
Recommended Citation
Fernandez, Federico, "The Effects Of Waste Leachates On The Hydraulic Conductivity Of Natural Clays (volumes I And Ii)" (1989). Digitized Theses. 1832.
https://ir.lib.uwo.ca/digitizedtheses/1832