Disposal of Waste Material – Evaluation in the KHM Project of Short and Long-Term Effects

Abstract

One of the main objectives of the Swedish Coal-Health-Environment Project is to assess the short and long term effects of the disposal of coal wastes on the environment. The situation described below has been the basis for the discussions, laboratory leaching tests and field studies carried out in the KHM Project. The results of the laboratory works are reported to the conference in a paper by Liem et al, while this paper discusses the water balance and construction measures. Certain trace elements in coal wastes are found in greater concentrations than in normal soils and rocks. As a result of the mineral alteration in the combustion process the mobility of some of the constituents may be higher in the waste than in the coal (or in sediments in general). On the other hand the alkaline properties of the waste reduce the mobility of many elements. Due to the continuous leaching out of buffering substances the pH of the leachate water will vary with time. The construction of trace elements in the leachate from a waste dump, exposed to acid rain, is governed by several factors. Beside the trace element composition and the leaching characteristic of the waste, the buffering capacity, the time and the water balance of the dump are judged to be the main controlling factors.