Dumped Ammunition in Mine Shafts Hydrogeochemical Evaluation of Two Mine Shafts at Dalkarsberg. A Repository for Decommissioned Ammunition and Other Explosives

摘要

Ammunition and explosives have been dumped at Dalkarsberg in two water-filled mine shafts, the Central shaft and the Backaskog shaft. The future hydrogeological status of the repository has been evaluated, based on field investigations and mathematical modeling. The field investigations consisted of borings and chemical analysis of water from the shafts. The flow and transport in the tunnel system and in the fractured rock mass were simulated by use of three-dimensional models. The heterogeneous properties of the rock mass were represented by a stochastic continuum. The models predict that all the water in these two shafts, as well as all transported pollutants, will discharge to the surface water system in the very near vicinity of the uppermost part of the Backaskog shaft. All pollutants will end up in a small stream located close to the shafts. We conclude that the explosives (TNT and lead acid) as well as metals present in the mineshafts as a result of diffusion from the dumped material will be completely released after about 2 000 to 20 000 years. Because of a relatively high dilution in the shafts, the amount of released components in the water will be very low. The main conclusion is therefore to leave the dumped material in the shafts and install a monitoring system for future water analysis.