The changes that have taken place in the British Coal Industry over the last five years have meant that in many coalfileds the last deep mines have closed. When a coalfield is abandoned and dewatering ceases, groundwater levels rebound, threatening surface waters with polluting discharges. However, the sparse data sets available limit modelling with existing techniques. A lumped parameter model GRAM (Groundater Rebound in Abandoned Mineworkings) has been developed. This model conceptualises a coalfield as a group of 'ponds'. Each pond is an area of the coalfield that has been extensively worked and can be considered as a single hydraulic unit. The ponds are connected by pipes which represent major inter-connecting roadways along which flow is assumed to be turbulent. Discharge to the surface is also represented using pipes. Flow through the pipes can be calculated using the Prandtl and Nikuradse of the Colebrook-White pipeflow equations. The storage coefficient can vary vertically to represent both worked Coal Measures and the intervening unworked strata. GRAM is able to predict the timing and volume of discahrges. An iron component gives an indication of the water quality evolution of the discahrges. Monte Carlo simulation allows the variables that have most error in their estimation to be represented by probability distributions. The Dysart-Leven Coalfield in eastern Fife, Scotland has not been mined since 1985. However, dewatering has continued to protect the workings in the Frances Colliery. In 1994 British Coal decided the Frances would never reopen, there is therfore no longer a need to continue dewatering. GRAM has been used to produce estimates of the quantity, timing and location of dischargges from the Dysart-Leven Coalfield should pumping cease. MODFLOW has also been applied to the coalfield with less success. Water quality modelling was also attempted using GRAM's iron component, however, conclusive results will not be obtained until the three variables over which ther is most uncertainty have been calibrated against existing discharges.

No description available.

No description available.

Returning waste material underground, as backfill, has been practiced for many years so as to improve the economical and environmental performance of underground mining operations. A specific type of backfill, which is used to fill mined areas that will not be exposed to further mining, is called hydraulic backfill. Cemented backfill has also been used to provide mechanical support for underground mining. Such backfill has allowed mining companies to extract more ore, while simultaneously improving working and environmental conditions. Cemented backfill, however, represents 50 to 85 percent of operating costs compared with the 5 to 10 percent that hydraulic backfill consumes. / The objective of this thesis is to investigate use of sodium silicate as a partial or total replacement for cement in stabilised backfill. Sodium silicate is a viscous material that is usually used to activate pozzolanic materials such as slag and fly ash. The chemical compound has many applications, namely, in waste treatment, cement and other construction materials. / In order to determine the influence of sodium silicate on backfill performance, a series of laboratory experiments were carried out on samples with different binder compositions, such as: cement; slag and cement; slag, cement and sodium silicate; and slag and sodium silicate. Additionally, the effects of mixing time and addition order on the backfill samples' performance were studied. The subsequent thesis focuses mainly on the strength of paste and slurry backfill samples containing sodium silicate in addition to the observation of a number of experimental variables, which include: pulp density (relative amount of water), curing time, and binder dosage. In order to investigate the overall suitability of sodium silicate for use in stabilised backfill, other properties such as porosity, elastic modulus, and trends of water release are also studied. / The results of the research endeavour demonstrate that sodium silicate-fortified backfill materials behave favourably compared with cemented backfills. Sodium silicate, thus, has potential as a backfill binder or additive.

Thesis (MEng)--University of South Australia, 1998

Bibliography: p. 368-375. / xv, 375 p. : ill. (chiefly col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Laboratory tests using a wide range of additives have been undertaken to develop hardpans more akin to naturally occurring duricrusts. Some additives have developed cements which have the low permeability and porosity characteristics required, while maintaining a high level of resistance to both chemical and physical breakdown. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1999

Thesis (MEng)--University of South Australia, 1998

Bibliography: p. 368-375. / xv, 375 p. : ill. (chiefly col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Laboratory tests using a wide range of additives have been undertaken to develop hardpans more akin to naturally occurring duricrusts. Some additives have developed cements which have the low permeability and porosity characteristics required, while maintaining a high level of resistance to both chemical and physical breakdown. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1999

Thesis (M.S. - Geology)--University of Arizona. / Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1988. / Vita. Abstract. Includes bibliographical references (leaves 132-145). Also available via the Internet.