Watson, AH 2006, 'Better Closure Cost Estimates', in AB Fourie & M Tibbett (eds), Mine Closure 2006: Proceedings of the First International Seminar on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 493-497, https://doi.org/10.36487/ACG_repo/605_41
(https://papers.acg.uwa.edu.au/p/605_41_Watson/)
Abstract: The most important element of sustainability in mining is that we stay in business. There are over 23000 
abandoned mine openings from activity pre-1970, in the State of Colorado alone. Those early miners did not 
consider the cost associated with any activity external to the extraction of ore, and made no provision for 
retiring their mining assets when the lode played out. Approximately 3500 of those disturbances have been 
closed with Federal and State funds since the inactive mines program was implemented in the 1980s, and the 
State of Colorado is responsible for closing the rest of them eventually.  There are currently approximately 
6000 mines in Colorado permitted under the post-1970s mining law, requiring reclamation bonding.  This is 
just one example of the many mining districts around the world where we have work to do.