Are pit lakes an environmentally sustainable closure option for opencast coal mines?

Abstract

The aim of the study is to determine if pit lakes are a sustainable coal mine closure option in South African. The water balance, chemistry, limnology, and bacterial population of three selected pit lakes were investigated. The lakes are in the three major coal basins of South Africa and are associated with different lithologies and mining methods. The major factors driving the water balance of the pit lakes are direct rainfall, runoff, inflow from old mine workings, and groundwater infiltration, with the major losses being evaporation or discharge onto surface. The study indicated that pit lakes can be designed as 'terminal sinks' to provide a sustainable mine closure option. The pit lakes sampled have an alkaline pH, and mostly a sodium/calcium sulphate water with total dissolved solids content of less than 3000 mg/l. The phytoplankton and microbiological data indicates that the pit lakes support aquatic life. The study shows that correctly designed pit lakes can be an environmentally sustainable closure option for South Africa's coal mines. A suggested design manual has been developed to assist mine owners and regulators in developing sustainable coal mine pit lakes as a closure option.

Comprehensive evaluation of coal mine pit lake hydrological connectivity in South Kalimantan, Indonesia

“…There have been many studies on mine rehabilitation, including landform design for mine rehabilitation [32], land reclamation progress [33], restoration of minedegraded land [34], soil properties development in mine reclamation [35], soil heavy metals in coal mine [36], mine closure [37]. Meanwhile, there have been studies on pit lake aspect, such as pit lake restoration for ecological and social bene t [38], water balance and water quality [39], risk assessment of pit lake [40], sustainable pit lakes [25]. This paper offers comprehensive and integrative approach as it examined not only the result of 9-years-old of post mined rehabilitation that act as a catchment area for the pit lake but also covers downstream areas outside the post mined area that are hydrologically connected.…”