The former Konrad iron ore mine at Salzgitter, Germany, is proposed to be used as a radioactive waste repository. The mining drifts of the Konrad site are covered by thick clay layers and are bounded laterally and below by salt domes that provide an excellent low permeability geological barrier. We present simulation results on a 40 × 2.5 km vertical 2D model of the Konrad site that include the effects of salt dissolution on groundwater flow. The simulations were done in steady state with the finite element code NAMMU. The main objective of this work was to evaluate quantitatively the effects of the downward increase in salinity of the groundwater on the vertical flow through the disturbed zones (e.g. back filled shafts and boreholes) in the clay barrier. The presence of salt caused a significant decrease in the vertical flow velocities of the major aquifers at a location far from the waste site, which in turn decreased horizontal flow near the waste site. The net effect of the decreased aquifer flow and increased gravity forces was to slightly increase vertical flow in the intact clay barrier above the waste site. The presence of salt, however, did significantly reduce upward velocities by over one order of magnitude for disturbed zones that may penetrate the geological barrier. This means that even hydraulically strongly disturbed zones would have no negative effect on the long-term safety of the proposed site.
|Original language||English (US)|
|Number of pages||10|
|State||Published - 1996|
All Science Journal Classification (ASJC) codes
- Water Science and Technology