Since January 1997, Barrick Gold Corporation’s Les Terrains Auriferes (LTA) tailings site has been the subject of a detailed study MEND Project 2.22.4 aimed at assessing the performance of a composite cover placed on the acid generating tailings impoundment. The full scale composite cover was built in the winter of 1996 on the 60 hectare site. Alkaline tailings were used for the fine material layer. In addition to being the first full scale cover of this type (e.g. oxygen barrier) in Canada (and possibly elsewhere), this project offers the added advantage of using mine tailings, a waste product.

The main objective of this report is to describe the various phases of the LTA project, from the initial conceptual design of the cover to the final construction and monitoring. The theory behind composite covers and design methods have already been thoroughly discussed in the literature; the present report will, therefore, be a practical field application example of this technology.

This report will describe initial concerns, the flow charts used in the decision process, the laboratory work performed as well as the fundamental properties of all the materials used for construction. Sequence of events, construction difficulties will be presented subsequently along with monitoring instruments used. Analytical results outlined in this report will allow preliminary comparison of properties observed in laboratory and in situ.

Conclusions will be formulated and discussed to assess the applicability of this technology to other sites. A final monitoring report will be available in 1999.