Pit lakes as the focus of sustainable development - how to preclude a post-closure disaster

Stuck in the warm sun besides the beach in southern California this week, I still had time to look up some papers on mine open pit lakes.  This was done a part of an ongoing debate about sustainable development.   I debate as follows:  obey the law in spirit and verse–and if the jurisdiction is too corrupt to do it correctly, practice responsible mining; drop the concept of sustainable development in the context of mining–the words have too long being incorrectly used to promote irrational ideas to be of much value any more; rather talk about responsible mining–a broader and more ethical approach that incorporates the sensible parts of sustainable development;  and finally make sure that when the mine is worked out, people can continue to enjoy life, liberty, and the pursuit of happiness in, around, and in spite of the mine.  Spook is a good example of what I mean.  No chance for China here though.

Here are a few tid-bits I came across on pit lakes:  Pit lakes at these mines are reported to have good quality water and to provide opportunities for recreational use and wild-life habitat: Copper Flat Mine, New Mexico, Yerington Mine, Nevada, and the Getchell Mine, Nevada. Conversely the Berkeley Pit at Butte, Montana contains acid waters that will probably have to be treated forever to prevent contamination of groundwater and surface water.

Here is the conclusion all would like to see from a study of post-mining pit lake development (from Stone, D. B., and Fontaine, R.C. (1998) Simulation of groundwater fluxes during open pit filling and under steady state pit lake conditions. Proceedings of the Conference on Hazardous Waste Research.)

Simulations of the filling of an open pit in Cresent Valley, Nevada were made to generate input to pit lake chemistry predictions. Under steady state conditions, the lake stage is lower than the elevation of the groundwater table in the pit area prior to mining. Groundwater flow is directed towards the pit lake, because evaporation from the pit lake causes it to act as a groundwater sink.

In the coal mines of Montana stripped overburden is used to backfill open pits. Here is the conclusion from a paper that describes studies of the quality of this backfill and it impact of long-term groundwater resources (from Straskraba, V. (1986) Ground Water Recovery Problems Associated with Open Pit Reclamation in the Western United States. International Journal of Mine Water. Vol 5 (4). 1986.)

Studies of water quality in spoils is not quite conclusive because of a relatively short period of monitoring of the impacts of open pit mining in the western United States. A general observation of groundwater quality in spoils is that the content of total dissolved solids, calcium, magnesium, and sulphate, when compared to the pre-mining conditions, is two to threefold higher at present. However, these levels should decline as leaching of the spoils reaches an equilibrium. Even at a threefold increases in the concentration of the total dissolved solids, the water in the spoils will, in most cases, be suitable for its predominant pre-mining use, namely stock watering.

 If you know of other pit lakes, successes & failures, please let me know, or comment below.