A basic understanding of the theoretical concepts which can be applied to prevent or at least reduce acid mine drainage from tailings through the use of dry covers has been obtained. Recent research has focussed on evaluating potential barrier materials. This has produced a multitude of suggestions with regards to alternate barrier materials and the direction of future dry covers research. This study reviews dry covers theory and current research; evaluates potential materials including several which have not yet been evaluated for use in covers; and after evaluation, provides recommendations regarding further dry covers research.

The theoretical concept of dry covers is reviewed and the barriers are classified as oxygen barriers (moisture retaining), oxygen consuming, or reaction inhibiting. Potential barrier materials are identified through a technical literature search; a literature review focussed on forest product industry wastes; and a search for potential materials that may be obtained from municipal and industrial waste streams. A short list of potential materials is developed applying a two stage screening process which takes technical aspects, cost, and practical application into consideration. Potential barrier materials considered to provide broadly based (country wide) benefit and a good likelihood for success are listed. Recommendations are made regarding the future direction of dry barrier research and specific research work currently underway.

Potential materials given a high priority for future research include natural soils, modified soils, desulphurized tailings, tailings slimes, wood waste, and paper mill sludge. Materials given a lower priority for future research include peat, waxes, ashes, and the PHITO layer. Available barrier materials not requiring additional research are limestone (mixed into the tailings mass), and synthetic liners.