This manual is as good a summary of all the relevant theory and practice of unsaturated cover design as any I have come across. Everything in the manual has been said before—whole conferences have been held on the topics. But I refer you to this manual, in case, like me, you have not previously come across it.

I refer to the CANMET – CETEM Manual on Cover System Design for Reactive Mine Waste (2002). The manual appears to have been compiled to train Brazilian Partners in mine rehabilitation initiatives in Brazil. It is not entirely clear who Brazilian Partners are, but we must compliment the authors O’Kane, Ayres, Christiansen, and Meiers of O’Kane Consultants Inc., for a thoroughly readable and informative document.

In this manual you will find a detailed discussion of cover design concepts, the basic theory of unsaturated flow in covers, guidance on soil-atmosphere cover design numerical modeling, guidance on the evaluation of materials for use in cover construction, pointers to cover field performance monitoring, some intelligent comments on erosion, surface water management, long-term evolution, and the performance of cover systems, and case histories.

I enjoyed the insight into the influence of sloping covers on cover performance, the modeling of air intrusion into waste piles that may generate acid drainage, and the detailed discussion of ways to monitor the performance of unsaturated covers.

An associated paper on an Australian case history is Linking Tailings Seepage Geochemistry to the Performance of Cover System Field Trials for a Tailings Storage Facility at Peak Gold Mine Operations by Meiers et al also of O’Kane Consultants. In this paper the authors report on field trails of a 1.5-m and a 2.0-m thick soil cover in an arid area of Australia. They report that the seepage resulting from the 1.5-m thick cover area is acidic, whereas the seepage from the area of the 2.0-m thick cover is near neutral with elemental levels characteristic of the process water. Moreover up to three times as much seepage appears to occur through the 1.5-m thick cover as through the 2.0-m thick cover.