Dragoljub Bajic

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.

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.