Mine waste covers are one of the many tools our industry uses to mitigate against the post-closure impacts of mining. Based on the overall closure objectives for a site, mine waste covers are designed to fulfill a specific set of “functions” for a defined timeline. The success with which these covers continue to perform the “functions” in accordance with design expectations, is subject to considerably different opinions, spanning the spectrum from optimism to pessimism.
The reality is that mine waste covers are thin engineered membranes covering vast volumes of potentially problematic mine waste, subject to continuous evolution of physical and chemical properties. We expect these thin membranes to perform their intended “functions” amidst an unrelenting and ever-changing onslaught of forces from Mother Nature, over a time period most commonly defined as “indefinite”. While Father Time may be indifferent to such timelines, cover practitioners need to be more realistic.
Over the last two decades a great number of mine waste covers has been constructed, but unfortunately there is an ever-increasing list of cases where cover performance has not stood the test of time, perhaps due to unrealistic expectations. Cover practitioners, regulators, and mine operators are not ambivalent to this reality and continuously strive to improve and advance mine waste cover technology. An unintended consequence of this may be that mine waste cover design is being “commoditized” through the ever-expanding development of cover guideline documents, which serve an important role in helping us “learn from our mistakes”, but perhaps stifle creativity and innovation. The author contends that these trends may be leading us towards adoption of prescriptive mine waste cover design approaches, which arguably could be setting back this technology substantially.
This discussion paper will describe and explore these concepts through the use of examples and is intended to provide some food for thought to cover practitioners, regulators, and mine owners alike. We have ambitious expectations of mine waste covers and therefore need to design them with sufficient armour to stand up to the clash with Father Time and Mother Nature.
