Instrumentation of a sealing layer made of a green liquor dregs- and bentonite amended till – Remediation of sulfidic mine waste

Abstract

In Sweden, the common method to stop sulfide oxidation and the production of acid rock drainage (ARD) from unattended sulfidic mine waste is the application of a dry cover solution on the waste. Recycling a non-hazardous industrial residue, such as green liquor dregs (GLD), in this cover solution is beneficial for both the mining industry where there is a great need for alternative materials and the providing industry by minimizing the waste deposited. The objectives of this field study were to install and evaluate the instrumentation of a sealing layer made of GLD- and bentonite amended till (respectively), and to evaluate two different methods of installation: monitoring wells and pits. Experiences from this study demonstrate that it is difficult to properly seal the drill holes after installation of the probes and suggest that the best alternative for future installation of instruments in a sealing layer might be to excavate a pit in the protection layer after installation of the soil cover and then drill the probes into the sealing layer from that pit.