PIT lakes as sustainable post-closure interventions for open-cast coal mines in the Indian context

Publication Type:

Conference Papers

Source:

Aqua Foundation's XIII World Aqua Congress: International Conference and Exhibition, Aqua Foundation's XIII World Aqua Congress, New Delhi (2019)

Keywords:

Ecosystems, Open-cast mine closure, Pit lakes, Sustainability, Water management

Abstract:

Coal is a pivotal link in balancing India’s increasing energy demands as well as infrastructure development, catering to about three-fourths of the country’s power generation. Ninety four percent of the coal produced in India is mined from more than 200 open cast mines in various parts of the country. While open-cast coal mines also have positive spinoffs for the local population in terms of infrastructure creation, jobs and business opportunities during the operation period,their impacts on the local ecology have been well documented. The changes to ecology during operative and post-closure phases demonstrate the need for improved mine closure planning so that the adverse impacts of opencast mining can be controlled in a more scientific manner compared to current mining practices in India. With the introduction of Section 20A in the Mines and Minerals (Development and Regulation) Act in January 2015, Parliament has empowered the Central Government to issue policy directives for “promoting restoration and reclamation activities so as to make optimal use of mined-out land for the benefit of the local communities.” Pit lakes are artificial waterscapes developed by filling-up of the voids with water via natural and/or artificial recharge. The sustainability of these ecosystems, however,is under investigation owing to the complexity of their interactions across the long-term geological and biological realms. In India, such approaches are quite novel and there is a need to evolve scientific measures to adopt pit lakes as sustainable alternatives to backfilling with excavated soil. The present study is an assessment of the efforts and plans of utilising pit lake ecosystems in India ascreative post-closure solutions for open-cast mining. Using examples of environmental statuses of the existing pit-lake ecosystems in India, analyses of their potentials as sustainable alternatives for backfilling has been explored. For the first time, the study will provide an understanding of the desired criteria to be planned while creating pit lakes. Using data from a compilation of scientific investigations, the impact of factors such as the mine closure planning, diversion of stream-flows, adoption of natural recharge, and the need for technological interventions for stabilising the ecosystem flows and conservation in these ecosystemswill be closely examined. Critical design factors such as lake depth, management of the monimolimnion, biological interventions, balancing the lake leakance versus seepage to aquifers, long-term contaminant transport etc. will be discussed. Finally, the need for policy changes to design the final mine void as part of a self-sustained ecosystem to serve the needs of the local communities will also be discussed with the idea of imparting long-term sustainability to these ecosystems