The detection and tracking of mine-water pollution from abandoned mines using electrical tomography

Increasing emphasis is being placed on the environmental and societal impact of mining, particularly in the EU, where the environmental impacts of abandoned mine sites (spoil heaps and tailings) are now subject to the legally binding Water Framework and Mine Waste Directives. Traditional sampling to monitor the impact of mining on surface waters and groundwater is laborious, expensive and often unrepresentative. In particular, sparse and infrequent borehole sampling may fail to capture the dynamic behaviour associated with important events such as flash flooding, mine-water break-out, and subsurface acid mine drainage. Current monitoring practice is therefore failing to provide the information needed to assess the socio-economic and environmental impact of mining on vulnerable eco-systems, or to give adequate early warning to allow preventative maintenance or containment. BGS has developed a tomographic imaging system known as ALERT ( Automated time-Lapse Electrical Resistivity Tomography) which allows the near real-time measurement of geoelectric properties "on demand", thereby giving early warning of potential threats to vulnerable water systems. Permanent in-situ geoelectric measurements are used to provide surrogate indicators of hydrochemical and hydrogeological properties. The ALERT survey concept uses electrode arrays, permanently buried in shallow trenches at the surface but these arrays could equally be deployed in mine entries or shafts or underground workings. This sensor network is then interrogated from the office by wireless telemetry (e.g: GSM, low-power radio, internet, and satellite) to provide volumetric images of the subsurface at regular intervals. Once installed, no manual intervention is required; data is transmitted automatically according to a pre-programmed schedule and for specific survey parameters, both of which may be varied remotely as conditions change (i.e: an adaptive sampling approach). The entire process from data capture to visualisation on the web-portal is seamless, with no manual intervention. Examples are given where ALERT has been installed and used to remotely monitor (i) seawater intrusion in a coastal aquifer (ii) domestic landfills and contaminated land and (iii) vulnerable earth embankments. The full potential of the ALERT concept for monitoring mine-waste has yet to be demonstrated. However we have used manual electrical tomography surveys to characterise mine-waste pollution at an abandoned metalliferous mine in the Central Wales orefield in the UK. Hydrogeochemical sampling confirms that electrical tomography can provide a reliable surrogate for the mapping and long-term monitoring of mine-water pollution

Simulation of an absorption based solar cooling facility using a geothermal sink for heat rejection

An important issue of solar cooling facilities based on absorption cycles and sometimes not given the necessary attention is the recooling process of the absorber and condenser. This is critical in the overall behaviour of the facility because the condensation and absorption temperatures will affect the COP and cooling capacity of the chiller. Most of the time the recooling process is made by using a wet cooling tower in a closed loop through the absorber and condenser. The use of a wet cooling tower gives good results in terms of cooling capacity and COP, but presents some health risk, like legionella, and its use is restricted to the industrial sector and places where water scarcity is not present. This paper presents the modification of the already validated TRNSYS simulation of a solar cooling facility, implementing a geothermal heat sink instead of the wet cooling tower in order to dissipate the heat generated internally in the absorption chiller. Simulation results shows that a geothermal heat sink composed of 6 boreholes of 100 meters of depth should be sufficient in order to substitute the wet cooling tower, for a typical Spanish single family dwelling.Universidad Carlos III de Madrid - ITEA Research GroupPublicad

Overview of technologies for constructing the facilities at the Dniester pumped storage power station

Purpose. Perform an overview of the construction technologies and substantiate the effectiveness of the Ukrainian experience in building a pumped storage power station (PSPS) on the Dniester River in difficult engineering-geological conditions with the construction of large underground structures, including mine shafts and hydraulic engineering tunnels. Methods. In the work, the main technological methods have been studied and analysed of hydraulic engineering construction of complex large underground structures in the rocks with medium hardness according to M.M. Protodiakonov scale using a special method of a well lowering and a combined method of drilling and blasting operations during mine workings drivage, which is based on the slow and short-delay blasting. The anchors calculation, when driving the water sup-ply conduits, has been made from the condition of suspending the block of disturbed rock, the thickness of which was taken equal to the roof arch height according to M.M. Protodiakonov. The parameters of the sprayed plaster base concrete have also been calculated according to V.M. Mostkov theory. Findings. The analysis of the current state of research, theoretical positions and world practice of construction of PSPS has been made, which testifies the high potential of this type of energy facilities. The efficiency of the underground hydraulic engineering construction of the Dniester Station has been substantiated. The results are presented of a complex application of mining and construction methods, as well as processing equipment for the construction of horizontal and tailrace conduits, drainage adits and vertical mines for hydraulic units in difficult engineering and geological conditions. As a result of performed analytical studies, the combined method of constructing the anchor support of sprayed plaster base concrete, when driving the water supply conduits, which is the most rational for engineering and geological conditions of increased complexity, has been substantiated. Originality. The efficiency of the lowering well method in a thixotropic jacket when constructing in the soft soils has been determined under the conditions of building a PSPS on the Dniester River. The step-by-step combined method of constructing the anchor support of sprayed plaster base concrete, when driving the water supply conduits has been substantiated. Practical implications. The most rational ways of conducting a range of mining-construction works have been substantiated and implemented, allowing to construct a complex pumped storage facility with a capacity of over 2.0 million kilowatts, ensuring a significant increase in the power supply capacity of the West Ukraine region.Мета. Виконати огляд технологій спорудження й виявити ефективність українського досвіду будівництва гідроакумулюючої електростанції на р. Дністер у складних інженерно-геологічних умовах зі зведенням великих підземних об’єктів, включаючи шахтні стовбури та гідротехнічні тунелі. Методика. В роботі розглянуті та проаналізовані основні технологічні способи гідротехнічного будівництва складних великих підземних споруд у скальних породах середньої міцності за шкалою М.М. Протод’яконова із застосуванням спеціального способу опускного колодязя й комбінованого способу ведення буропідривних робіт при проходці гірничих виробок на основі уповільненого і короткоуповільненого підривання. Розрахунок анкерів при проходці водоводів виконувався з умови підвішування блоку порушеної породи, товщина якого приймалася рівною висоті склепіння обвалення за М.М. Протод’яконовим. Розрахунок параметрів набризгбетону проводився також за теорією В.М. Мосткова. Результати. Виконано аналіз сучасного стану досліджень, теоретичних положень і світової практики будівництва гідроакумулюючих станцій, що свідчить про високий потенціал даного виду енергетичних об’єктів. Обґрунтовано ефективність підземного гідротехнічного будівництва Дністровської станції. Представлені результати застосування комплексу гірничопрохідницьких і будівельних методів та технологічного обладнання для спорудження горизонтальних і відвідних водоводів, дренажних штолень та вертикальних шахт для гідроагрегатів у складних інженерно-геологічних умовах. В результаті виконаних аналітичних досліджень обґрунтова- ний комбінований метод створення анкерного набризгбетонного кріплення при проходці водоводів, що є най- більш раціональним для інженерно-геологічних умов підвищеної складності. Наукова новизна. Для умов будівництва гідроакумулюючої електростанції на р. Дністер визначено ефективність методу опускного колодязя в тиксотропної сорочці при будівництві в слабких ґрунтах. Обґрунтовано поетапний комбінований метод створення анкерного й набризгбетонного кріплення при проходці водоводів. Практична значимість. Обґрунтовано й впроваджено найбільш раціональні способи ведення комплексу гірничобудівельних робіт, що дозволяють здійснювати будівництво складного гідроакумулюючого об’єкта потужністю понад 2.0 млнкіловат, що забезпечує суттєве підвищення енергоозброєності західного регіону України.Цель. Выполнить обзор технологий сооружения и выявить эффективность украинского опыта строительства гидроаккумулирующей электростанции на р. Днестр в сложных инженерно-геологических условиях с воз- ведением крупных подземных объектов, включая шахтные стволы и гидротехнические тоннели. Методика. В работе рассмотрены и проанализированы основные технологические способы гидротехнического строительства сложных крупных подземных сооружений в скальных породах средней крепости по шкале М.М. Протодьяконова с применением специального способа опускного колодца и комбинированного способа ведения буровзрывных работ при проходке горных выработок на основе замедленного и короткозамедленного взрывания. Расчет анкеров при проходке водоводов выполнялся из условия подвешивания блока нарушенной породы, толщина которого принималась равной высоте свода обрушения по М.М. Протодьяконову. Расчет параметров набрызгбетона производился также по теории В.М. Мосткова. Результаты. Выполнен анализ современного состояния исследований, теоретических положений и мировой практики строительства гидроаккумулирующих станций, свидетельствующий о высоком потенциале данного вида энергетических объектов. Обоснована эффективность подземного гидротехнического строительства Днестровской станции. Представлены результаты применения комплекса горнопроходческих и строительных методов и технологического оборудования для сооружения горизонтальных и отводящих водоводов, дренажных штолен и вертикальных шахт для гидроагрегатов в сложных инженерно-геологических условиях. В результате выполненных аналитических исследований обоснован комбинированный метод создания анкерной набрызгбетонной крепи при проходке водоводов, являющийся наиболее рациональным для инженерно-геологических условий повышенной сложности. Научная новизна. Для условий строительства гидроаккумулирующей электростанции на р. Днестр определена эффективность метода опускного колодца в тиксотропной рубашке при строительстве в слабых грунтах. Обоснован поэтапный комбинированный метод создания анкерной и набрызгбетонной крепей при проходке водоводов. Практическая значимость. Обоснованы и внедрены наиболее рациональные способы ведения комплекса горностроительных работ, позволяющие осуществлять строительство сложного гидроаккумулирующего объекта мощностью более 2.0 млн киловатт и обеспечивающего существенное повышение энерговооруженности западного региона Украины.The authors express their gratitude to Viacheslav Korytskyi, Deputy Chief Engineer of the Tunnel Construction Department No.7, PJSC “Kyivmetrobud”, for advisory support and provided drawings

Simulation of the spatio-temporal extent of groundwater flooding using statistical methods of hydrograph classification and lumped parameter models

This article presents the development of a relatively low cost and rapidly applicable methodology to simulate the spatio-temporal occurrence of groundwater flooding in chalk catchments. In winter 2000/2001 extreme rainfall resulted in anomalously high groundwater levels and groundwater flooding in many chalk catchments of northern Europe and the southern United Kingdom. Groundwater flooding was extensive and prolonged, occurring in areas where it had not been recently observed and, in places, lasting for 6 months. In many of these catchments, the prediction of groundwater flooding is hindered by the lack of an appropriate tool, such as a distributed groundwater model, or the inability of models to simulate extremes adequately. A set of groundwater hydrographs is simulated using a simple lumped parameter groundwater model. The number of models required is minimized through the classification and grouping of groundwater level time-series using principal component analysis and cluster analysis. One representative hydrograph is modelled then transposed to other observed hydrographs in the same group by the process of quantile mapping. Time-variant groundwater level surfaces, generated using the discrete set of modelled hydrographs and river elevation data, are overlain on a digital terrain model to predict the spatial extent of groundwater flooding. The methodology is applied to the Pang and Lambourn catchments in southern England for which monthly groundwater level time-series exist for 52 observation boreholes covering the period 1975–2004. The results are validated against observed groundwater flood extent data obtained from aerial surveys and field mapping. The method is shown to simulate the spatial and temporal occurrence of flooding during the 2000/2001 flood event accurately

An update of a simulation study of passively heated residemtial buildings

A simulation study of passively heated residential buildings” published in Procedia Engineering 2015 showed how circulating 15-17ºC water from a 50-m deep U-tube to a floor radiator and solar-heated water from a 30 evacuated tube solar collector and a 2-m3 indoor tank to a wall radiator could keep a 30-m2 Melbourne, Australia house thermally comfortable. This paper presents a summary of the ongoing review of publications together with three updates: - (1) Report on that water heated by a 100-metre deep U-tube is 22-24ºC, i.e., 2-4 ºC warmer than thermal comfort temperature. (2) May 2016 experimental validations of the simulated results which show that when the outdoors is below 10ºC, the temperature of the floor radiator is 2-4ºC less than the 15-17ºC water heated by a 50-m deep U-tube and 25 W fish tank pumps could circulate the waters. (3) Simulations with the addition of phase change materials (PCM) to inside faces show that though a PCM halves the diurnal indoor temperature variations, it confirms that such PCM does not significantly increase the 20ºC temperature in a 2-m3 storage tank at the end of winter. Therefore, the size of intersessional thermal storage would be a problem for family-sized houses. German Guidelines indicate that 1-2 boreholes could provide enough heat for family-sized houses. The heat extracted in winter can be replenished in summer. Thus the geothermal heat from about 100-m deep boreholes with 22-24ºC bottom temperature could sustainably keep residential buildings in cool climates similar to Melbourne's cool temperate thermally comfortable

Boreholes plans optimization methodology combining geostatistical simulation and simulated annealing

Nowadays, the prospection plans have the difficult task of ensuring a more complete and rich characterization of the rock mass for the purpose of optimizing costs and increasing safety in geotechnical projects. Currently, boreholes location and depth are mainly defined based on experience and know-how of professionals, as such, it is user-dependent. Hence, there is a lack of methodologies to help the decision-makers in defining the optimal location of boreholes (with relevant information). Therefore, this paper presents a methodology based on the use of geostatistical conditional simulation allied to a stochastic global optimization algorithm (Simulated Annealing) to develop optimized boreholes plans comparing a uni-objective and a multi-criteria optimization approaches. In this work, the optimized location is considered the one that minimizes uncertainty translated by either the average local variance or the average width of 95% probability intervals of simulated values at unsampled locations. This methodology was applied using preliminary information obtained from previously executed boreholes using as variable the empirical rock mass classification system, Rock Mass Rating, in a Chilean deposit.This research is inserted in LNEC project named P2I-RockGeoStat and was partially funded by FCT (Fundação para a Ciência e Tecnologia, Portugal) in the scope of project PEst-UID/CEC/00319/2013, included in ISISE project UID/ECl/04029/2013 as well as the PhD grant SFRH/BD/89627/2012, and by the Chilean Commission for Scientific and Technological Research, through Project CONICYT PIA Anillo ACT1407.info:eu-repo/semantics/publishedVersio

Modeling elastic wave propagation in fluid-filled boreholes drilled in nonhomogeneous media: BEM – MLPG versus BEM-FEM coupling

The efficiency of two coupling formulations, the boundary element method (BEM)-meshless local Petrov–Galerkin (MLPG) versus the BEM-finite element method (FEM), used to simulate the elastic wave propagation in fluid-filled boreholes generated by a blast load, is compared. The longitudinal geometry is assumed to be invariant in the axial direction (2.5D formulation). The material properties in the vicinity of the borehole are assumed to be nonhomogeneous as a result of the construction process and the ageing of the material. In both models, the BEM is used to tackle the propagation within the fluid domain inside the borehole and the unbounded homogeneous domain. The MLPG and the FEM are used to simulate the confined, damaged, nonhomogeneous, surrounding borehole, thus utilizing the advantages of these methods in modeling nonhomogeneous bounded media. In both numerical techniques the coupling is accomplished directly at the nodal points located at the common interfaces. Continuity of stresses and displacements is imposed at the solid–solid interface, while continuity of normal stresses and displacements and null shear stress are prescribed at the fluid–solid interface. The performance of each coupled BEM-MLPG and BEM-FEM approach is determined using referenced results provided by an analytical solution developed for a circular multi-layered subdomain. The comparison of the coupled techniques is evaluated for different excitation frequencies, axial wavenumbers and degrees of freedom (nodal points).Ministerio de Economía y Competitividad BIA2013-43085-PCentro Informático Científico de Andalucía (CICA

Field Measurements of Spontaneous Potential (SP) for Smart Well Monitoring and Control. A Field Test in the UK Chalk Aquifer

Imperial Users onl

Characterisation of the transmissivity field of a fractured and karstic aquifer, Southern France

International audienceGeological and hydrological data collected at the Terrieu experimental site north of Montpellier, in a confined carbonate aquifer indicates that both fracture clusters and a major bedding plane form the main flow paths of this highly heterogeneous karst aquifer. However, characterising the geometry and spatial location of the main flow channels and estimating their flow properties remain difficult. These challenges can be addressed by solving an inverse problem using the available hydraulic head data recorded during a set of interference pumping tests.We first constructed a 2D equivalent porous medium model to represent the test site domain and then employed regular zoning parameterisation, on which the inverse modelling was performed. Because we aim to resolve the fine-scale characteristics of the transmissivity field, the problem undertaken is essentially a large-scale inverse model, i.e. the dimension of the unknown parameters is high. In order to deal with the high computational demands in such a large-scale inverse problem, a gradient-based, non-linear algorithm (SNOPT) was used to estimate the transmissivity field on the experimental site scale through the inversion of steady-state, hydraulic head measurements recorded at 22 boreholes during 8 sequential cross-hole pumping tests. We used the data from outcrops, borehole fracture measurements and interpretations of inter-well connectivities from interference test responses as initial models to trigger the inversion. Constraints for hydraulic conductivities, based on analytical interpretations of pumping tests, were also added to the inversion models. In addition, the efficiency of the adopted inverse algorithm enables us to increase dramatically the number of unknown parameters to investigate the influence of elementary discretisation on the reconstruction of the transmissivity fields in both synthetic and field studies.By following the above approach, transmissivity fields that produce similar hydrodynamic behaviours to the real head measurements were obtained. The inverted transmissivity fields show complex, spatial heterogeneities with highly conductive channels embedded in a low transmissivity matrix region. The spatial trend of the main flow channels is in a good agreement with that of the main fracture sets mapped on outcrops in the vicinity of the Terrieu site suggesting that the hydraulic anisotropy is consistent with the structural anisotropy. These results from the inverse modelling enable the main flow paths to be located and their hydrodynamic properties to be estimated