The Canadian Water Quality Index (CCME WQI)

The pollution of water bodies from mining activity is often considered as a major threat to the environment and copper mining by its nature, consumes plenty of water for ore processing. In addition, the seeping/leaching of mine drainage water from waste rock piles or tailing dams into water resources also poses a potential threat of water pollution (Tiwari, et. al. 2016).

When mined materials (such as the walls of open pits and underground mines, tailings, waste rock, and heap and dump leach materials) are excavated and exposed to oxygen and water, acid can form if iron sulfide minerals (especially pyrites) are present in the host and there is an insufficient amount of neutralizing material such as limestone, to counteract the acid formation

These three factors combine to produce a value between 0 and 100 that represents the overall water quality (Khan et. al., 2004).

Factor 1: F1 (Scope)

Scope assesses the extent of water quality guideline for non-compliance over the time period under consideration, which means it indicated the percentage of parameters whose objective limits are not met. It has been adopted directly from the British Columbia Water Quality Index

Where, the variables indicate those water quality parameters whose objective values (threshold limits) are specified and observed values at the sampling sites are available for the index calculation.

Factor 2: F2

Deviation of pH, Iron and manganese are the primary factors contributing to lower down the WQI values and thus plunging the index scores from ‘Good’ to ‘Fair’ or ‘Marginal’ category.

Deviation of pH and iron concentration from the permissible limit of ISDW-2004 was observed in most of the hand pump water samples whereas only a few open dug well water samples showed relatively less deviation. This could probably be due to the effect of local hydrogeology as majority of the open dug wells are confined within the weathered granitoid zone that varies between 15-25 m in depth depending upon the topography of the area. While on the other hand, the depth of the hand pumps is confined within the in-situ zones which are probably more reactive than weathered zone.

In this study the CCME-WQI was used as a tool to evaluate water quality and delivered decisive assessment data for making judgment regarding water management at the largest copper mine in India. The CCME WQI provides a valuable means of monitoring, communicating, and understanding water