APPLICATION OF RISK BASED COST-BENEFIT ANALYSES FOR DECISION MAKING IN ENVIRONMENTAL RESTORATION OF URANIUM MINING AND MILLING SITES

摘要

Active and abandoned uranium mining and milling sites can represent complex environmental situations, where health risks and environmental detriments may result from radon exhalation and dispersion of radioactive dust from mine wastes as well as from the discharge of contaminated mine waters into surface and groundwaters. The paper outlines a methodology for the evaluation of remediation measures in the framework of the closeout of uranium mining and milling facilities in eastern Germany. The decision making process for the remediation of large waste rock dumps (total volume approximately 125 million m~3) at a uranium mining site is used as an example. In the context of this approach, appropriate and sustainable remediation measures should (1) reduce the environmental impacts from the waste rock dumps to acceptable levels, and (2) have the best cost-benefit ratio (i.e. the 'lowest overall costs'). These 'overall costs' comprise direct short term costs for remediation measures (e.g. application of engineered covers, backfill of mine waste into open pits), long term costs (e.g. for monitoring, maintenance, seepage collection/treatment), as well as the monetary equivalents of remaining risks for human life and health and impacts on the environment -evaluated by geochemical modelling/air dispersion modelling - in the long term. Uncertainties in the costs and benefits of the remediation measures are addressed by stochastic methods (Monte Carlo simulations).