Environmental Impact of Mine Water from Chemical Extraction and Underground Uranium Mining – Straz pod Ralskem, Czech Republic Josef V. Datela) , Vladimír Ekertb) a) Charles University in Prague, Faculty of Science, Albertov 6, 128 43, Prague 2, Czech Republic, e-mail:
[email protected] b) DIAMO, state enterprise, Machova 201, 471 27 Straz pod Ralskem, Czech Republic, e-mail:
[email protected] Abstract During the second half of the 20th century, there was large-scale exploration and production of uranium ores in the Czech Republic. The biggest uranium deposit area was found in the North-Bohemian Cretaceous area in the mid-1960s. During 30 years of production, approximately 30,000 tons of uranium concentrate was produced. More than 15,000 drill holes were drilled in the area and almost 11,000 of them were cased and used as production and monitoring (hydrogeological) wells. Both classical underground (room and pillar) mining and in situ leaching (ISL) methods were used in the area. A mill and two tailings impoundments were also constructed in the area. Sulphuric acid was used as leaching agent to process ore from both mining methods. More than 4 million tons of sulphuric acid was injected into the ground for the ISL method. This affected approximately 338 3 -1 2- 2 million m of groundwater (limit 0,25 g.l SO4 ) over an area of more than 26 km . The adverse influence of these activities has yet to be mitigated. Key words: uranium mining, in situ leaching, chemical extraction, groundwater contamination, Cretaceous basin, Czech Republic Introduction Czech Republic's uranium ore deposits are found in North Bohemia, in an area adjoining the towns of Mimon, Straz pod Ralskem, and Krizany, in the Liberec region.