Degradation of the Surface and Subsurface Water Quality on the Adjacent Area of Barapukuria Coal Mine due to the Improper Effluent Treatment of Mine Waste Water

(1)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 5, Issue 2, February 2015)

458

Degradation of the Surface and Subsurface Water Quality on

the Adjacent Area of Barapukuria Coal Mine due to the

Improper Effluent Treatment of Mine Waste Water

Sharmin Akter

1

, Tusher Mohanta

2

, Chowdhury Quamruzzaman

3

, Zidmi Ahamad Ringko

4

,

Md Zonaed Hossain Sazal

5

, Md. Badrul Alam

6

1,2,4

M.S Student, Department of Geology, University of Dhaka, Bangladesh

3

Professor, Department of Geology, University of Dhaka, Dhaka-1000, Bangladesh

5,6_{Research Assistant, Department of Geology, University of Dhaka, Bangladesh}

Abstract-- Coal is a highly potential natural resource that largely contributes in the development of economics of a country by producing power and metallurgical industry and so on. In perspective of Bangladesh, about 4% of power is generated from good quality of bituminous coal from BARAPUKURIA COAL MINE. But the resurgence of coal deteriorates the environment by polluting air, water and soil. The aim of this research was to gather information about the impacts of coal mining on surface water as well the ground water that carried out in Barapukuria coal mining area of Northwest region in Bangladesh and propose some suitable techniques to beat the resulted problems. According to the current research, the mine drainage water becomes acidic (Ph 6 to 7.4 in surface water and 5.5 to 6.5 in underground water) and contains large amount of ions (Na+_{:18.451-35.5,Ca}2+ :29.9-50.64,Mg2+:5.65-14.65, HCO3

_

: 91.5-167.75) that highly contaminates the surrounding area. Thus the adjoining agricultural area is getting vulnerable for the farmers to their cultivable land. Finally, from the environmental degradation point of view, author suggested a reorganized mining policy, an Environmental impact assessment (EIA) and some proper effluent treatment plants of discharge the mine drainage water to mitigate its destructive effects on environment.

Keywords-- Barapukuria coal mine, Bituminous coal, Hydrogeology, Quality of water, EIA.

I. INTRODUCTION

About 39% of total energy is produced by coal globally, thus the development of a country largely depends on the production of coal. Bangladesh is one of the small amounts of coal producing country that started its journey since 2005. Among the five coal fields, Barapukuria coal field at Dinajpur (Fig.1) is only operating coal field in Bangladesh. Barapukuria coal field was discovered in 1985 after the discovery of 157m thick Gondwana sediment by Geological Survey of Bangladesh (GSB).

Fig: 1. Location map of Barapukuria coal field in Dinajpur district, Bangladesh

(2)

International Journal of Emerging Technology and Advanced Engineering

459

In this study, an attempt was taken to collect the information about the impacts of coal mining on surface water as well the ground water and aquatic environment surrounding the Barapukuria coal basin and interpret the resultant data for the clarification of impacts of coal mining in order to show relationship between coal mining and its impact on water and aquatic environment, with a exceptional focus on remediation to overcome the resulted problems.

II. HYDROGEOLOGY OF BARAPUKURIA

[image:2.612.51.285.336.637.2]

Within areal extent of about 5.25 square kilometer, 7 coal bearing seams are encountered with a total thickness of about 74.14m. Hydrostratigraphy of this area is given in Table 1.

Table-1

Hydrostratigraphic succession of the Barapukuria coal mine

Among the 7 coal seams, coal seam 6 contains maximum reserve which is about 90% of total coal field reserve, also poses the highest thickness about 36 m (average). Coal seams are mainly of massive Gondwana group and they are underlying by the unconsolidated Dupitila formation that is the major aquifer in that area.

Having some recharge characteristics, the mine area is enclosed by semi-confined aquifer. W. A. company reveals that upper Dupitila aquifer is thicker than others and the transmissivity as well as the storage coefficient of roof and floor of coal seam 6 is good. Comparing the lower dupitila, sandstone of coal seam 6 is a direct water filling aquifer that can affect on mining. A good hydraulic relationship has been found between the lower section of UDT and the sandstone of seam-6 roof. (CMC, 1994).

III. METHODOLOGY Investigated Area

[image:2.612.317.588.355.645.2]

The investigation was based on field observations, sample collections, data collection and onsite measurement. 16 samples were collected from groundwater and surface water in different location of the mine and in and around the mine area. This distribution of samples is showing below in a map (Fig.2).

Fig: 2. Sample distribution in Barapukuria

Physio chemical parameter

(3)

International Journal of Emerging Technology and Advanced Engineering

460

From the study, it had been observed that groundwater and associated mine discharges vary widely in ph value from near neutral (pH 6 to 7) to slightly acidic (pH 4.5 to 5.5) (Fig.3). This range of pH shows a bimodal frequency distribution (Fig.4) that is controlled by mineralogy and hydrology of the mine.

Fig: 3. Distribution of pH value in various locations with line diagram

Fig: 4. Bar diagram of bimodal Distribution of pH

The pH values of the surface water is between 6 to 7.4 with a mean value of 6.6 and a standard deviation of 0.5 indicate neutral pH, and the pH range of Underground mine water is 5.5 to 6.5, and the mean value is 5.9, standard deviation is 0.42,indicate acidic in nature. The mean value of pH is 6.6 to 5.9 in the mine drainage and the surface drainage respectively indicate slight acidic water (Fig.5). The pH increased with distance from the discharge point (Fig.6).

Fig: 5. Box and whisker plots showing variations of pH values in underground mine drainage water (MWS) and surface Drainage

water (SWS) samples.

Fig: 6. Distribution of pH value from mine discharge point

(4)

International Journal of Emerging Technology and Advanced Engineering

461

The studies also indicate that, where calcareous minerals are absent or deficient, the oxidation of only small amounts of pyrite under stagnant water-saturated conditions can produce AMD (pH < 5 and SO4 > 200 mg·L-1); these conditions commonly are found at flooded underground mines.

Whereas, electrical conductivity (EC) shows a greater difference between surface mine drainage water and underground mine drainage water (Fig.7). In surface, the range is between 366 to 465 µs/cm, with a mean of 454 µs/cm and a standard deviation of 46.51 µs/cm and in underground mine drainage EC was lower than the surface discharged water samples, ranging from 290 to 439 µs/cm with a mean of 362.5 µs/cm and a standard deviation 49.03 µs/cm (Fig.8). Both ranges are too less than the water quality standard of Bangladesh. With the help of EC the value of TDS is been detected in between 200-600 mg/l.

Fig: 7. Distribution of Ec in different point

Fig: 8. Box and whisker plots showing variations of EC values in UWS and SWS

On the other hand, Temperature was found to be quite higher than the Bangladesh water quality standard (20°-30.2° Celsius).

Underground mine drainage water had distinctly much higher range (37 to 43˚C) of temperature than the temperature range (23.6 to 30˚C) in the surface drainage water with a mean of 39˚C and a standard deviation of 2.31˚C (Fig.9).

Fig: 9. Box and whisker plots showing variations of Temperature values in mine water samples and Surface water samples

After laboratory analysis, it has been revealed that chemical compounds vary widely from water quality standard. In the following table (table.2), amount of cations and anions are shown below.

Table-2

(5)

International Journal of Emerging Technology and Advanced Engineering

462

Variation of the concentration of anions and cations in specific location is shown in following diagrams (Fig 10-13).

[image:5.612.325.572.133.298.2]

Bar Diagram-

Fig :10. Bar diagram of concentration of chemical compounds

Piper Diagram-

[image:5.612.50.285.191.355.2]

Fig: 11. Piper diagram showing the major ions

[image:5.612.326.570.319.486.2]

Fig: 12. Box & Whisker diagram showing the major ions in surface

Fig: 13. Box & Whisker diagram showing the major ions in subsurface

From these analysis it has been observed that the dominanat facies of this region is Ca2+-Na+-HCO3-. The

major anion trend for mine drainage water was HCO3– > Cl– > SO42–> PO43–. The major cations trend for mine drainage water was Ca2+ > Na+ > Mg2+–> K+.

IV. IMPACTS ON WATER

Coal is a very important but dirty fossil fuel. Coal mining has rigorous environmental, ecological, human-health consequences. If not done properly, coal mining has potential to damage landscape, soils, surface water, groundwater, air during all phases of exploration and use.

The water requirement for Barapukuria thermal power plant is 60ton/hr for each unit. Among these water 30ton/hr is drained that is mainly acidic in nature and rest of water is recycling. AMD, classified as hard water, contains harmful heavy metals and metalloids like HCO3

[image:5.612.49.291.387.711.2]

(6)

International Journal of Emerging Technology and Advanced Engineering

463

Due to the lacking of waste disposal system and surface-water-diversion structures, AMD production is getting higher in recent days. This provides an unavoidable negative impact both on the surface and underground water. The increase in PH level is a proper example of this condition.

Groundwater supplies may be adversely affected by mine waste water. These impacts include drainage of useable water from shallow aquifers, lowering of water levels in adjacent areas and changes in flow direction within aquifers, contamination of useable aquifers below mining operations due to infiltration (percolation) of poor quality mine water and increased infiltration of precipitation on spoil piles.

Agriculture and domestic users also suffers intensely as it spoils the soil condition which makes it difficult in proper crop production. Drinking water is being polluted even in the inhabitant area far from the plant. Thus it may act as a pestilence specter. Physio-chemical environment inconsistency provides an impact on downstream aquatic flora, fauna, and fisheries that debates the water quality. If aquatic fauna is affected severely, it could upset the ecological balance. A total of six aquatic fauna species were recorded from the study area. Out of six aquatic faunas one is endangered and one is threatened. A total of eight aquatic floras were recorded from the project area. Besides the danger to life and property, large amounts of sediment and poor-quality water may have detrimental effects many miles downstream from a mine site after a flood.

V. REMEDIATION

The revitalization coal may come as an alarm to some because of ecological impacts it has had in the past. However, by means of proper Environmental Impact Assessments (EIA) and Environmental Management Plan (EMP) these impacts can be controlled.

As AMD is the responsible for pollution of water in and around the mine area that’s why it is mandatory to control the overall situation in order to maintain the balance in water quality. In some cases CO2 is used as a buffering

agent to minimize the AMD supply as well as the PH value.

It may also be neutralize by using different chemicals like lime, various fertilizers etc.Authors suggested that a proper effluent treatment plant must be conducted and mine water should be treated before discharge to rise above these troubles.

VI. CONCLUSION

In Barapukuria, water is being polluted thoroughly due to untreated mine drainage. As the drainage water is acidic and contains large amount of heavy metals thus it provides harmful distress on surrounding area. As Bangladesh largely depends on production of coal thus it is vulnerable to stop the production. Hence it is compulsory to minimize its harmful effects on environment. Taking proper effluent treatment plant of discharge, waste water disposal system, survivors can get rid of this problem. In some instance authors concluded that an updated mining policy and an Environmental impact assessment should be followed in accordance with dispose.

REFERENCES

[1] China National Machinery Import and Export Corporation (CMC), 1994. A Supplementary Hydrogeological Feasibility Study of Barapukuria Coal Basin, Dinajpur, Bangladesh (Unpubl).

[2] Harun-Or-Rashid1, Md. Abu, Salauddin Shanto1, Dhrubo Ronjon, Roy1, Md. Sanower Hossain2, Md., Sirajul Islam1, Mir Md. Mozammal Hoque1 and Zannat Urbi2, Impact of coal mining on soil, water and agricultural cropproduction: a cross-sectional study on Barapukuria coalmine industry, Dinajpur, Bangladesh

[3] Chowdhury Quamruzzaman, Md. Abdul Matin Mondol, Mohammad Tofayal Ahmed, S. M. Mainul Kabir, Zubair Ahmed. A Proposal of Open Pit Coal Mine at the Northern Part of Barapukuria Coalfield, Dinajpur, Bangladesh

[4] Uddin, M.N. and Islam, M.S.1992. Gondwana Basins and their Coal Resources in Bangladesh. Geology in South Asia -1. Proc. First South Asian Geol. Cong. Pakistan, p.224-230.

[5] Bakr, M.A., Rahman, Q.M.A., Islam, M.M., Islam, M.K., Uddin,M.N., Resan, S.A., Haider, M.J., Sultan-Ul-Islam, M., Ali, M.W.,Chowdhury,M.A., Mannan, K.H. and Anam, A.N.M.H., 1996,Geology and Coal Deposit of Barapukuria Basin, Dinajpur Districts,Bangladesh. Records of Geological Survey of Bangladesh, vol.8 part 1p36.