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An investigation of chloride Ion levels In coarse colliery discards was undertaken because modem British Coal practice is to restore discard tips and lagoon embankments at an early stage in construction, commonly before much leaching has taken place. High chloride ion concentrations result in physiological drought and the failure of vegetation cover. Sites at two collieries were studied using grid and traverse (depth) sampling procedures. Results Indicate downward leaching of chloride ions into the embankment during Winter months and an increase in chloride levels towards the surface of the discard during dry, summer months. Salt hotspots occur on embankment surfaces during Summer months. These high chloride/sulphate concentrations represent the desiccation of seepages, most of which are related to embankment construction inadequacies, rather than to lagoons incorporated into the structure. Chlorides within the discard originate from formation waters intimately associated with Coal Measures sequences. In the eastern coalfields in particular, high chloride ion concentrations in the coal and waste rock from deep underground excavations are not removed by the coal washing processes. Consequently, they are retained in fresh colliery discards. Seasonal movements of chloride ions are associated with an increase In (negative) suction pressures within the near-surface layers of a colliery embankment. Suction pressures were monitored experimentally in two experimental tips and in the field at a third colliery site (Bilsthorpe Colliery). On an annual basis, suction pressures become operative early in April, reversing to residual negative or small positive pore pressures in mid-September. The leaching of chlorides from discard embankments is a function of the drainage characteristics of the materials and in clayey discards leaching to low levels is shown to take 5 to 7 years. Hotspots do not decrease significantly. The results of the present investigation can be applied to current embankment restoration schemes. In particular, the sowing of an embankment during the Autumn window, when electrolytes move downwards into the structure, would enable young vegetation to become established before being subjected to the higher Summer chloride concentrations. Hotspots require individual field drainage treatment.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1983. / Vita. Abstract. Includes bibliographical references (leaves 95-105). Also available via the Internet.

Thesis (Ph. D.)--Université de Nantes, 1982. / Series statement stamped on flyleaf. Includes bibliographical references (p. 137-140).

Strip mining in Kentucky has left large areas of land that could potentially be used for business and housing developments. However, the mine spoils underlying these areas are prone to severe differential settlement due to a variety of factors. Mine spoil from the Gateway Business Park in Jenkins, Kentucky was used for a series of laboratory tests to develop relationships between shear wave velocity, confining stress, compaction energy, and dry unit weight to develop a method to assess settlement potential. It was found that a stress-corrected shear wave velocity of greater than 275 ft/s/psi0.25 typically indicated dry mine spoil, and less than 275 ft/s/psi0.25 typically indicated wet mine spoil. Equations were developed to predict the amount of settlement of a mine spoil profile based on the load, the mine spoil lithology, and the shear wave velocity of the mine spoil. With regards to compaction, it was found that if the mine spoil was compacted to at least 120 pcf (18.8 kN/m3), or a void ratio of 0.45 or less, the mine spoil would suffer little to no volume change when wetted. The results provided herein form the basis of a methodology for screening mine spoil sites for development based on settlement potential.

No description available.

Digitized by Kansas Correctional Industries

Thesis (M.S.)--Mississippi State University. Department of Civil Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains x, 64 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 63-64).

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