Pre-mining Conditions Research Articles

English

West Virginia Department of Environmental Protection's Division of Mining and Reclamation has initiated a new effort to promote reforestation of mined lands in West Virginia. goal of this initiative is to expedite the establishment of commercially valuably native timber stands. Forest productivity, species diversity, and natural invasion and succession will be emphasized. Traditional methods of reclamation have produced sites with decreased productivity compared with the pre-mining conditions. Compaction of the growth media, poor quality overburden materials used in the growth media, competition from ground covers, inferior species of trees planted, and poor tree planting techniques including timing, have all contributed to decreased productivity on many of our past reforestation efforts. new reforestation technology encourages reforestation of mine sites through developing an optimal growth medium, loosely grading topsoil and topsoil substitutes, establishing less aggressive ground covers, planting commercially valuable crop trees, and using proper tree planting techniques. The New West Virginia Mine Land Reforestation Initiative includes regulatory changes, education, training and technology transfer.

Avaliação de três áreas de solo construído após mineração de carvão a céu aberto em Lauro Müller, Santa Catarina

Em solos construídos após mineração de carvão, a contaminação das camadas superficiais com pirita provoca intensa acidificação do solo, acelera a intemperização de minerais, eleva os teores de Al e Mn e aumenta a lixiviação de bases. O presente trabalho avaliou características químicas, teor de argila e mineralogia, bem como a variabilidade espacial para algumas dessas características em três áreas de solos construídos após mineração de carvão a céu aberto no município de Lauro Müller, Santa Catarina. As três áreas selecionadas apresentavam diferenças no modo de construção topográfico. A primeira, denominada Mina Juliana (MJ), foi construída em 1996, utilizando material (sólum, regolito argiloso e rocha) que foi separado e estocado antes da mineração, conforme previsto no plano de reabilitação. A segunda, denominada Mina do Apertado (MA), foi construída, em 1996, usando, como material de cobertura, o sólum proveniente do decapeamento de um morro adjacente à área. A terceira área, denominada Mina Rio do Meio (MRM), sofreu apenas construção topográfica em 1983, com mistura de resíduos de pirita de carvão e rochas de várias camadas. Amostras de solo foram coletadas em sistema de grade de pontos, em três profundidades, sendo analisados o pH em água, teores de Ca, Mg, K e Al trocáveis, H + Al e condutividade elétrica. Em amostras selecionadas, analisaram-se alguns metais pesados e a mineralogia da fração argila. Análises efetuadas em dois perfis de solo representativos das condições anteriores à mineração foram utilizados, para comparação. Todas as áreas apresentaram grande dispersão de valores para características químicas e teor de argila dos solos entre os pontos amostrados. O processo de construção do solo que resultou em maior uniformidade destas características e melhores condições para o estabelecimento de espécies vegetais foi o da área MJ. O solo da área MA, graças à mistura de resíduos de carvão piritoso com o solo superficial, está em franco processo de acidificação e contém alta concentração de sais. O solo da área MRM, em virtude do abandono e do longo período de exposição de resíduos piritosos na camada superficial, mostra elevada acidez, tendo já sofrido intensa lixiviação dos sais. As únicas variáveis testadas que apresentaram modelo definido para semivariância foram Al trocável, H + Al e argila, cujo alcance variou de 50 a 70 m.

What can element budgets of false-time series tell us about ecosystem development on post-lignite mining sites?

The post-lignite mining landscape in Lusatia, Germany, is dominated by sandy substrates of Tertiary and Quaternary sediments. Lignite and pyrite contents of varying amounts can result in extremely phytotoxic site conditions. To establish pine stands on these sites, large amounts of CaO were used for amelioration. The development of these ecosystems in 2–60–year–old pine stands on two typical substrates in a ‘false-time series’ approach was studied. Continuous measurements of weather data, soil tensions and soil water contents, together with regular sampling of rainwater and soil solutions at different soil depths, were used to calculate element fluxes through the ecosystems and outputs from the soil. Soil solution compositions indicate very high spatial and temporal dynamics. Over time, sharp depth gradients are formed as a result of amelioration and due to soil forming processes. Acid production by pyrite oxidation, weathering of primary minerals, precipitation of secondary salt and mineral phases, and leaching of salts down the profile are the dominating processes at the lignite and pyrite containing sites. These processes result in long-term soil and site conditions that are very different from pre-mining conditions or compared to non mined soils of the region. Soil solutions are mainly composed of Ca T, Al T, Fe T, and SO 4T depending on soil pH and pyrite content. The dynamics in lignite- and pyrite-free sands are much less pronounced and overall show much lower concentrations. The element outputs from the systems on pyritic substrates can reach very high levels.

Stream response to subsidence from underground coal mining in central Utah

Short-term geomorphic and hydrologic effects of subsidence induced by longwall mining under Burnout Creek, Utah were evaluated. During the year after longwall mining, 0.3–1.5 m of subsidence was measured near impacted reaches of the mountain stream channel. The major channel changes that occurred in a 700-m reach of Burnout Creek that was subsided from 1992 to 1993 were: (1) increase in lengths of cascades and to a lesser extent glides; (2) increases in pool length, numbers and volumes; (3) increase in median particle diameter of bed sediment in pools; and (4) some constriction in channel geometry. Most of the changes appeared short-lived, with channel recovery approaching pre-mining conditions by 1994. In a 300-m reach of the South Fork that was subsided from 1993 to 1994, only channel constriction was observed, although any impacts on pool morphology may have been confounded by heavy grazing in the riparian reaches during the dry summer of 1994. Similar near-channel sedimentation and loss of pool volume between 1993 and 1994 were noted throughout Burnout Creek and in adjacent, unmined James Creek. Subsidence during the 3-year period had no effect on baseflows or near-channel landslides.

Sediment dynamics in the Castleton karst, Derbyshire, U.K.

Chemical and mineralogical data are presented for a suite of 59 sediment samples collected from the P8 and Speedwell cave systems (and mineralogical data are presented for a further six surface sediments) in the Castleton karst catchment, Derbyshire, England. Sediments are grouped according to age and depositional environment and these groups show distinctive mineralogical and chemical characteristics. Clay mineralogy is effective at distinguishing different sediment sources for ancient and modern sediments which are derived from pre-Devensian tills and Devensian solifluction deposits, respectively. Major element chemistry reflects these differences in clay mineral content, while trace elements demonstrate the importance of abrasion of ore minerals in conduits in the aquifer which follow mineral veins, even under natural, pre-mining conditions. Clay minerals are confirmed as the host for uranium in uranium-rich ancient sediments. Consideration of organic carbon and hydrogen concentrations shows that plant material is the dominant source of organic material in the modern sediments. Copyright © 1999 John Wiley & Sons, Ltd.

Sediment dynamics in the Castleton karst, Derbyshire, U.K.

Chemical and mineralogical data are presented for a suite of 59 sediment samples collected from the P8 and Speedwell cave systems (and mineralogical data are presented for a further six surface sediments) in the Castleton karst catchment, Derbyshire, England. Sediments are grouped according to age and depositional environment and these groups show distinctive mineralogical and chemical characteristics. Clay mineralogy is effective at distinguishing different sediment sources for ancient and modern sediments which are derived from pre-Devensian tills and Devensian solifluction deposits, respectively. Major element chemistry reflects these differences in clay mineral content, while trace elements demonstrate the importance of abrasion of ore minerals in conduits in the aquifer which follow mineral veins, even under natural, pre-mining conditions. Clay minerals are confirmed as the host for uranium in uranium-rich ancient sediments. Consideration of organic carbon and hydrogen concentrations shows that plant material is the dominant source of organic material in the modern sediments. Copyright © 1999 John Wiley & Sons, Ltd.

Geochemistry of Water and Mobilization and Transport of Solutes in Coal Mine Spoils, East-Central Texas

Reclamation of surface mines in Texas became mandatory in 1978, requiring that overburden removed during surface mining (mine spoils) be emplaced in open mine pits and land surface reshaped to pre-mining topography. The reclaimed land surface then is revegetated to control erosion. Shallow ground-water-flow systems that develop in reclaimed areas have geochemical characteristics substantially different from pre-mining conditions. Because the solutes produced by mine spoils potentially can degrade the quality of ground and surface water, the mining industry has developed methods of spoils emplacement and surface reclamation to mitigate these effects. Comparisons of chemical data from ground water collected from two coal mine reclamation sites in east-central Texas and results of a laboratory-controlled, column-leaching experiment on reclaimed spoil material from the area indicate that large amounts of solutes are mobilized from the spoil material. Increased concentrations of dissolved solids (550 to 6,050 milligrams per liter), dissolved sulfate (73 to 2,800 milligrams per liter), dissolved iron (2,000 to 160,000 micrograms per liter), and dissolved manganese (800 to 13,000 micrograms per liter) and low pH (4.0 to 6.2) in ground water from two reclaimed areas indicate these to be the primary water-quality concerns. However, reclamation practices and establishment of strongly reducing environmentsmore » in shallow ground water inhibit mobilization and transport of trace elements (including radium-226 and uranium-238, which are present in very small amounts in the ground water). Mass-balance models indicate that pyrite oxidation and dissolution of halite, carbonates, amorphous alumina, amorphous silica, and to a lesser extent, gypsum are reaction processes occurring in reclaimed spoils. Sulfate reduction was apparent in the aquifers from detection of sulfide in ground water; however, the magnitude of sulfate reduction was not substantial in mass-balance models.« less

CUMULATIVE HYDROLOGIC IMPACT ASSESSMENTS ON SURFACE-WATER IN NORTHEASTERN WYOMING USING HEC-1; A PILOT STUDY

The Surface Mining Control and Reclamation Act of 1977 requires that areas in which multiple mines will affect one watershed be analyzed and the cumulative impacts of all mining on the watershed be assessed. The purpose of the subject study was to conduct a cumulative hydrologic impact assessment (CHIA) for surface-water on a watershed in northeastern Wyoming that is currently being impacted by three mines. An assessment of the mining impact`s affect on the total discharge of the watershed is required to determine whether or not material damage to downstream water rights is likely to occur as a result of surface mining and reclamation. The surface-water model HEC-1 was used to model four separate rainfall-runoff events that occurred in the study basin over three years (1978-1980). Although these storms were used to represent pre-mining conditions, they occurred during the early stages of mining and the models were adjusted accordingly. The events were selected for completeness of record and antecedent moisture conditions (AMC). Models were calibrated to the study events and model inputs were altered to reflect post-mining conditions. The same events were then analyzed with the new model inputs. The results were compared with the pre-mining calibration. Peak flow, totalmore » discharge and timing of flows were compared for pre-mining and post-mining models. Data were turned over to the State of Wyoming for assessment of whether material damage to downstream water rights is likely to occur.« less

ERODIBILITY AND SEDIMENT YIELD BY NATURAL RAINFALL FROM RECONSTRUCTED MINE SOILS

Standard erosion plots, 4.6 m × 22.1 m with a 9% slope, were established at the Alston Surface Mine in Ohio County, Kentucky. Topsoil, subsoil, and mine spoil were reconstructed according to contemporary reclamation techniques using bulldozers and scraper pans. The following parameters were evaluated under natural rainfall conditions: runoff, erodibility, and sediment yield. Mine spoil yielded significantly greater runoff volumes, compared with reconstructed topsoil and subsoil. Average curve numbers (CN) were 89.1, 90.1, and 94.7 for bare topsoil, subsoil, and mine spoil, respectively. The subsoil plot generated the largest amount of sediment and was significantly more erodible than topsoil and mine spoil. The average annual erodibility (K) factor was .046 for topsoil, .067 for subsoil, and .051 for mine spoil, with units of Mg ha h (ha MJ mm)−1. Erodibility of the mine spoil in this study was more than twice that measured from an earlier rainfall simulation study at this same site. Differences in the degree of physical weathering were believed to be the primary contributing factor and, therefore, have important implications when assessing the erodibility of highly weathered spoil materials (e.g., abandoned mine lands). Compared with the soil interpretation record's K factor estimate for the soil series evaluated in this study, the reconstructed topsoil was not inherently more erodible than when existing in its natural, undisturbed condition. Therefore, factors that the mine operator can control (e.g., slope, vegetative cover, management practices) will likely have a greater impact on whether erosion losses from reconstructed soils are significantly greater than losses that occur under pre-mining conditions.

Evaluation of potential topsoil productivity

A biomass productivity model based on soil properties and climate is developed from literature and used to evaluate and compare potential effects of mining and reclamation on several soils in the continental United States. Soil productivity is assumed to vary as a product of root distribution function modified by five soil properties: available water, aeration porosity, bulk density, electrical conductivity, and pH. Yield limiting property levels are derived from literature and input soil data are obtained from available USDA Soil Conservation Service information on typical profiles. Modelled values of potential productivity after mining, indicate problems and limitations to be expected. The proposed model can be used as a guide to reclamation strategy, to restore the land to premining conditions, or at times to enhance productivity of a reclaimed area.

Measuring the environmental effect of marine mining

Marine mining may disturb the natural marine environment-solids, fluids, or organisms-by removal of materials, addition of foreign material, in-place mixing of existing material, or removal and subsequent replacement of material. Measuring the scope of such disturbances, of course, requires knowing the environmental conditions both before and after mining. Scientists disagree on what constitutes an adequate knowledge of baseline (premining) conditions, and instrumentation and techniques for measuring are not yet satisfactory. A wide range of instrumentation is necessary to measure the many physical, chemical, and biological factors involved. Some measurements must span enough time to encompass natural cyclic changes, but such long-term measurements are hampered by the lack of reliable submersible instrumentation. Inadequacy of measurement capability, for technical or economic reasons or both, is particularly evident regarding dispersion of fine solids and dissolved chemicals in mid-water and benthic layers and, to a lesser extent, in the surface layer of seawater. Especially difficult to measure or predict is the biological effect of mining. The most significant changes may be induced subsequent to the mining operation and may be some distance from it. Secondary effects resulting from these changes may not be obvious, but it is important that they be identified so that predictions can be made for other operations. Planned experiments to improve capability for prediction of effects should reduce the variety of measurement required. Many investigators fail to recognize the value of existing data banks, which consequently receive insufficient institutional financial support.