Dušan Polomčić

Application of Groundwater modeling for designing a dewatering system: Case study of the Buvač Open Cast Mine, Bosnia and Herzegovina

This paper presents groundwatermanagement based on the results of groundwater modeling used to simulate theeffects of operation of three dewatering system scenarios of the Buvac open pitmine. Several aquifers exist within the Buvac limonite ore deposit region,which puts ore exploitation at risk. Groundwater modeling, was used tounderstand the groundwater regime within these aquifers. A previous numericalmodel (2007) was completed for the state of the groundwater regime prior to theopening of the open pit mine. During the last five years, the development ofthe open pit mine and associated activities have drastically modified the flowfield. The model was modified for the new conditions on the site, and with thenew data from the groundwater and surface water regime monitoring. The existingsystem of protection of the open pit mine from groundwater encompasses drainageof the alluvial aquifer and the ore body aquifer. This paper analyzes threescenarios of the open pit protection from groundwater for the period from 2013to 2024. The new model was used to simulate the effects of operation of thethree proposed dewatering systems. The differences in the effects of operationof the scenarios were quantified through the conditions of groundwater levelsand water budget. Recommendations have also been given for performingprediction calculations in the case of existence of drainage wells, with themost effective dewatering system determined from a hydrodynamic aspect. Theresults presented in this paper may be used for developing an effectivedewatering program.

Origin of Fluorine in Mineral Waters of Bujanovac Valley (Serbia, Europe)

This paper deals with mineral and thermomineral water occurrences of the Bujanovac valley in south eastern part of Serbia related to granitoides of the Bujanovac massif along both the margin and the floor of the valley. In past decades (1966–2010) numerous hydrogeological, hydrogeochemical and geophysical explorations were carried out. One of results of these explorations is the completion of test holes and exploratory—production wells. They provide groundwater for three water bottling factories: “Heba”, “Bivoda”, “Prohor” as well as the “Vrelo Bujanovac Banja Spa Centre” for rehabilitation, treatment, and prevention. All stated consumers use the same mineral water aquifer. The content of fluoride in the majority of examined mineral waters is higher than 4 mg/1, whereby they are singled out as typical fluoride waters. The content of calcium ions in them amounts 80 mg/1, and the values of the saturation index in relation to calcium fluoride (SI) range from 0.4 to 0.7 mg/1, which points to mineral waters saturated in relation to fluorite. However, in the study area, there are mineral water occurrences with the content of fluoride significantly lower than in the majority of analysed waters representing hydrochemical anomalies. These waters occur as hydrochemical anomalies in marl and sandstone wherein Secondary mineral water aquifers, originating from cracked granite of the Bujanovac massif, are formed. When mineral waters from granite (with the increased content of fluoride) reach these secondary aquifers, the content of fluoride ions lowers to about 1 mg/1, which is of great significance from the point of view of mineral water utilisation as table bottled water. In this paper, it is proved that, in addition to the presence of some minerals as basic fluorine bearers, the role of the lithological environment where the natural process of defluoridation occurs is significant, which is confirmed by the revitalization of the A-4 well. The paper deals with mineral water deposits of the Bujanovac valley, and the natural way of lowering of fluorine content in the given waters.

Multi-Criteria Decision Analysis for the Purposes of Groundwater Control System Design

The best way for an engineer or scientist to express their knowledge, experience and opinions is day-to-day verbal communication. When a decision needs to be made about an optimal groundwater control system, the decision-making criteria need not always be numerical values. If fuzzy logic is used in multi-criteria decision-making, the criteria are described by linguistic variables that can be represented through fuzzy membership and expert judgment is used to describe such a system. Prior hydrodynamic modeling of the aquifer regime defines the management scenarios for groundwater control and provides an indication of their effectiveness. In this paper, the fuzzy analytic hierarchy process is applied to deal with a trending decision problem such as the selection of the optimal groundwater management system. Linguistic variables are used to evaluate all the criteria and sub-criteria that influence the final decision and the numerical weights of each alternative are determined by mathematical calculations. The paper presents a part of the algorithm – fuzzy optimization in hydrodynamic analysis, which leads to the selection of the optimal groundwater control system. The proposed method is applied in a real case study of an open-cast mine.

Updated 'budapest method' for revitalizing radial collector wells and applicability to Belgrade's water supply source

Belgrades water supply source is faced with the complex issue of halting a continuing decline in radial well capacity. It is possible to counteract the problem by replacing worn-out laterals. Past research has provided a basis for undertaking radial well revitalization activities. One of the questions that remained unanswered was how to overcome structural limitations - shallow emplacement of laterals. In Budapest, an innovative revitalization procedure, applying a modified Ranney method, has been used effectively for about 15 years. The laterals are installed below the bottom of the original well shaft and the screen pipes have bridge-like slots. The possibility of applying this method at Belgrades water supply source is substantial.

Design of the Opencast Coal Mine Drmno Dewatering System

Development of mining in the opencast mine Drmno from Kostolac basin in Serbia is carried out in the increasingly complex geological and hydro-geological conditions with the decline of the coal seams to the alluvial part of Europe’s largest river Danube. Greater depth and inflow of groundwater significantly increase costs for dewatering facilities construction with the requirement for optimizing of this more and more important surface mining process. Making decision on screen construction in the opencast mine with redesign of line wells parameters for the defence against groundwater, in addition to geology and hydrogeology exploration activities, analyzing the elements of the opencast mining systems and a number of working environment parameters with the development of the hydrodynamic model requires necessary review of economic and environmental effects. A detailed techno-economic analysis has been done in order to demonstrate technological justification and economy of screen construction as the system for protection against groundwater in the opencast mine. The defence of the opencast mine against the groundwater without the construction of screen causes construction of several dewatering wells and lines with increased pumping capacities by the end of deposit mining. On the other hand, screen construction means big initial investments but with a smaller number of dewatering wells with reduced capacities, lower cost of electricity and larger reliability of the system operation in the long period until the closure of the opencast mine. Estimates of environmental impact and efficiency comparison between these systems options for protection against of groundwater have been done. DCF analysis has shown that the long-term averaged costs for opencast mine Drmno dewatering against groundwater per ton of coal are approximate for the both system options. Final decision on the approval of the combined dewatering system with a reduced number of dewatering wells and screen construction has been caused by the system reliability and environmental effects related to the impact on the groundwater level outside of the opencast mine boundaries and safer operation of the hydro power plant Djerdap system on the Danube River.