Infiltration water dating from tritium measurements in mining dumps: methodic specifics and case study

Mine waste dumps and industrial tailings often emit toxic substances like sulfuric acid, heavy metals, or radionuclides over seepage discharge. An important parameter to characterize these transfer processes is the mean residence time tm of the infiltration water usually determined from tritium measurements. Conventional models assume a constant reservoir size (aquifer thickness) and to a great extent stationary hydraulics.
Emerging dumps, in contrast, exhibit a more or less continuously increasing thickness during deposition. The infiltration water is partly or even completely consumed to build up a static reservoir of adhesive water in the initial dry pores. The water percolation begins not until the field capacity is reached. This deceleration depends on deposit rates, recharge rates and cap-illary capacity and increases the portion of older components in the effluent waters compared to model assumptions.
In a case study a time series of effluent waters from a mining dump of Kupferschiefer mining in the south-eastern Harz-foreland was analyzed for ³H. The interpretation using the linear model revealed contradictions between residence time of infiltration waters and life span of the dump.
For the case of the linear model a proposal is made to modify the residence time distribution function. The