POST-FLOODING WATER MANAGEMENT AT THE RONNEBURG URANIUM MINE: LESSONS LEARNED AND REMAINING CHALLENGES

Remediation activities at WISMUT’s Ronneburg mine site, the formerly largest individual uranium mine in Europe, were focused on waste rock stabilization and the closure of the huge underground mine. After 9 years of mine flooding increasing groundwater levels reached the surface in mid 2006, and contaminated mine waters started to discharge to a water collection system which had been erected in a valley region. Due to the poor water quality mine waters as well as contaminated seepage and surface waters have to be treated for radionuclides, heavy metals and iron, a water treatment plant is operating since 2006. The paper compares model predictions with the real situation after mine flooding has been completed, in terms of water flow rates, exfiltration areas, and water quality. The recent water management practice is being described, discussing the key targets in terms of the water quality of different creeks and rivers downstream of the mine site. To sustainably run the water collection and treatment systems over at least two decades from now, adjustments to the existing technical systems are necessary, which will also be discussed. The experience gained so far underlines the need for comprehensive planning for flooding, but also for a flexible approach as part of a mine closure management plan which allows continuous updating of initial planning and corrective actions on the basis of monitoring data acquired during the flooding process. 1