HYDROGEOLOGICAL CONDITIONS IN THЕ ZHELEZNITSA MINERAL WATER DEPOSIT, PROSPECTS FOR DEVELOPMENT

ABSTRACT. The Zheleznitsa mineral water deposit is located in the fence massifs of the Sofia Graben, on the northern side of the Plana pluton, and around 2 km to the east of the village of Zheleznitsa. It is manifested by two groups of natural springs: the group in the valley of the Selska River and a group in the valley of the Vedena River. A total of 13 springs comes out through fissures in the diorites of the Plana pluton, the largest two being captured by concrete shafts. To uncover additional quantities, two design and exploitation boreholes were subsequently drilled, which were left to self-fill, and as a result, the flow rate of the high-lying springs dried up. The chaotic use of this water over the past 30 years, mainly associated with a collapsing mineral bath, carpet washing, and water logging of part of the outflows into the river in the form of small stone pools, necessitates a comprehensive assessment of the available archive data, analysis and summarising of the existing hydrogeological and hydrochemical information. Guidelines are offered for disclosing the full potential of the deposit and achieving a sustainable and manageable yield of good quality and higher temperature, with a view to the potential for utilisation.