5.2 Qualitative analysis of groundwater in mines

The qualitative assessment of groundwater samples (or surface water samples) from the mining area and surrounding areas is required to infer water quality (WQ) and thereby knowing its suitability for various uses. The mine water vary greatly in terms of concentrations of various chemical constituents, as water quality is likely to be affected with mine site parameters which are specific in nature.

Various studies on interrelationship between water quality, geology, and mining activities have been carried out in Indian mines [11, 15, 21, 31–33]. Similar studies and attempts are in vogue with reference to the different mines around the world, and their list is exhaustive.

Water quality assessment can be done either by field method(s) or by laboratory method(s). Their related aspects, that is, quality parameters and its selection for analysis, characterization, field sampling, water storage before and after lab analysis, periodical monitoring of quality for drawing inference, etc., require in-depth description parameter-wise [34]. For this, standard operating procedure (SOP) can be applied [35], and available literature on the specific subject can be referred for the details. Their elaborate description (field and laboratory method) has not been described in this chapter because ample of literature is available on the water quality and its assessment, even some of it is described by other authors in this book itself.

As regards water quality in mines, the following comes into the reader's mind— (i) the water quality of surface channels flowing in the mining area; (ii) the mine pit water quality; (iii) dump/spoil bank water quality; and (iv) tailing ponds/ impoundments water quality. Depending on the type of mineral excavated, the quality issues are to be recognized and assessed, for example, acid mine drainage problems are a severe water quality issue in the case of coal mines. The elemental analysis (pH, TDS, total hardness, etc.) is needed for limestone and dolomite mine, whereas lead-zinc, copper, iron ore, and bauxite mines (mines of metallic minerals/ ore) require attention toward heavy metal constituent's analysis.

Inseparable surface water and groundwater and its pollution can be assessed or evaluated qualitatively. Some important water quality parameters and major possible water contaminants and pollution indicators for mining and allied industry are shown in Tables 4 and 5. Having determined the value of each parameters, may be either low/high or within permissible limit/outside permissible limit, the scientific explanation of pollution status can be given. For each of the studied case, the pollution parameters that accounts are different and as according to the water usages. It is also recognized that the mine water quality, which is present in the mine or in the surrounding areas around the mine sites; in shallow aquifers and deep aquifers of mine sites, though not comparable with one another but governed by the same scientific principles/groundwater chemistry. Chosen WQ parameters are hence critical for valuation.

By knowing the water quality, one can easily trace back the source(s) of pollution, and management measures can be taken accordingly. Further, it is helpful and suggestive to know the background history also for proper assessment of WQ. Advances in instrumentation, modern computational technology, and improved management techniques are able to reduce many negative impacts arising out of water quality pollution.

It is found that the pH of the mine water fluctuates both ways from the normal range of 7 and the total hardness (TDS) parameter also varies considerably depending on the prevailing hydrological regime and the variation in lithology. These parameters mainly decide the mine water suitability for domestic, irrigation, and other miscellaneous uses. The anion and the cation chemistry (dominated by HCO3 ˜/SO4 ˜ concentration and Ca2+ and Na2+ ions, respectively) and hydrochemical facies (Mg-Ca-HCo3 and Mg-Ca-HCO3-Cl, etc.) knowledge can put forward the water chemistry mechanism for its various uses [36]. By knowing parametric values of various chemical parameters, sodium absorption ratio and residual sodium carbonate and acidity/salinity of mine water can be determined or assessed.

## Mining of Minerals and Groundwater in India DOI: http://dx.doi.org/10.5772/intechopen.85309


#### Table 4.

Some important water quality parameters


#### Table 5.

Main possible groundwater contaminants and pollution indicators in mining and allied industry

Thus, in brief, it is learnt that assessment of water quantity and quality is a pre-requisite for planning and development of mine. Mining of minerals at shallow depth can be done without adversely affecting the groundwater; however, when mine/mining goes deep, that is, below water table, the need to check its quantity, availability, and scientific management arises. Both quality and quantity assessment parameters are since field-based; a minor departure in filed values is possible. Nearly (˜) 20% departure from actual scenario is generally observed and admissible. By overcoming field measurement difficulties and adopting standard operating procedure (SOP), near accurate evaluation of groundwater can be done.
