Quantitative assessment of mine water sources based on the general mixing equation and multivariate statistics

Abstract

It is sometimes necessary to quantify the different sources of water entering a mine, based on the hydrochemical nature of the waters from individual aquifers that contribute to the mine water mixture. In order to solve the general mixing equation, a software tool, KYBL-7, was developed; its computational methodology is generally based on the balance of selected components of mine waters in steady state conditions, without considering chemical reactions. This approach was applied in the Sokolov Coal Basin, which is situated in the immediate vicinity of Carlsbad (Karlovy Vary), a worldwide renowned spa in the northern part of the Czech Republic. The technology and coal mining methods used in the Sokolov Coal Basin are limited due to its proximity to the Carlsbad thermal springs. Because of their social and economic significance, these springs are protected. Calculations proved that the Carlsbad waters contribute approximately 3 % to the mine water. The imbalance in the mine water mixture using known source waters was quantified by including an ‘unknown source’ in the mixture simulation. Geochemical modelling demonstrated that the water quality is a result of geochemical reactions of waters in contact with the atmosphere and the reverse dissolution of the accumulated precipitates in the open pit areas. Those results have been used to assess future technical measures that can be taken to protect the Carlsbad thermal waters.